Age-Related Sympathetic Ganglionic Neuropathology: Human Pathology And Animal Models

Journal of the Peripheral Nervous System 7:205–212 (2002)

© 2002 Peripheral Nerve Society, Inc.

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Neuropathy Abstracts

Abstracts of selected articles recently published in the medical literature

CONDITIONAL DISRUPTION OF BETA 1 INTEGRIN IN SCHWANN CELLS IMPEDES INTERACTIONS WITH AXONS

Feltri ML, Porta DG, Previtali SC, Nodari A, MigliavaccaB, Cassetti A, Littlewood-Evans A, Reichardt LF, Messing

A, Quattrini A, Mueller U, Wrabetz L.

Journal of Cell Biology156: 199–209, 2002.

Reprinted with permission from Rock-efeller University Press

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In dystrophic mice, a model of merosin-deficient con-genital muscular dystrophy, laminin-2 mutations produceperipheral nerve dysmyelination and render Schwann cellsunable to sort bundles of axons. The laminin receptor andthe mechanism through which dysmyelination and impairedsorting occur are unknown. We describe mice in whichSchwann cell-specific disruption of beta1 integrin, a compo-nent of laminin receptors, causes a severe neuropathy withimpaired radial sorting of axons. Beta1-null Schwann cellspopulate nerves, proliferate, and survive normally, but do notextend or maintain normal processes around axons. Inter-estingly, some Schwann cells surpass this problem to formnormal myelin, possibly due to the presence of other lamininreceptors such as dystroglycan and

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4 integrin. Thesedata suggest that PI integrin links laminin in the basal lamina tothe cytoskeleton in order for Schwann cells to ensheath axons,and alteration of this linkage contributes to the peripheralneuropathy of congenital muscular dystrophy.

HOMOZYGOUS DEFECTS IN LMNA, ENCODING LAMIN A/C NUCLEAR-ENVELOPE PROTEINS, CAUSE AUTOSOMAL RECESSIVE AXONAL NEUROPATHY IN HUMAN (CHARCOT-MARIE-TOOTH DISORDER TYPE 2) AND MOUSE

De Sandre-Giovannoli A, Chaouch M, Kozlov S, Vallat JM,Tazir M, Kassouri N, Szepetowski P, Hammadouche T,

Vandenberghe A, Stewart CL, Grid D, Levy N.

AmericanJournal of Human Genetics 70: 726–736, 2002.

Reprinted

with permission from The University of Chicago Press, http://www.journals.uchicago.edu/ajhg/home.html

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The Charcot-Marie-Tooth (CMT) disorders comprise agroup of clinically and genetically heterogeneous hereditarymotor and sensory neuropathies, which are mainly character-ized by muscle weakness and wasting, foot deformities, andelectrophysiological, as well as histological, changes. A sub-type, CMT2, is defined by a slight or absent reduction of nerve-conduction velocities together with the loss of large myelinatedfibers and axonal degeneration. CMT2 phenotypes are alsocharacterized by a large genetic heterogeneity, although onlytwo genes-NF-L and KIF1Bbeta-have been identified to date.Homozygosity mapping in inbred Algerian families with autoso-

mal recessive CMT2 (AR-CMT2) provided evidence of linkageto chromosome 1q21.2-q21.3 in two families (Z(max)

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4.14).All patients shared a common homozygous ancestral haplotypethat was suggestive of a founder mutation as the cause of thephenotype. A unique homozygous mutation in LMNA (whichencodes lamin A/C, a component of the nuclear envelope) wasidentified in all affected members and in additional patientswith CMT2 from a third, unrelated family. Ultrastructural explor-ation of sciatic nerves of LMNA null (i.e.,

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) mice was per-formed and revealed a strong reduction of axon density, axonalenlargement, and the presence of nonmyelinated axons, all ofwhich were highly similar to the phenotypes of human periph-eral axonopathies. The finding of site-specific amino acid substi-tutions in limb-girdle muscular dystrophy type 1B, autosomaldominant Emery-Dreifuss muscular dystrophy, dilated cardi-omyopathy type 1A, autosomal dominant partial lipodystrophy,and, now, AR-CMT2 suggests the existence of distinct func-tional domains in lamin A/C that are essential for the mainte-nance and integrity of different cell lineages. To our knowledge,this report constitutes the first evidence of the recessive inher-itance of a mutation that causes CMT2; additionally, we sug-gest that mutations in LMNA may also be the cause of the ge-netically overlapping disorder CMT2B1.

A NOVEL NEUTROTROPHIC PROPERTY OF GLUCAGON-LIKE PEPTIDE 1: A PROMOTER OF NERVE GROWTH FACTOR-MEDIATED DIFFERENTIATION IN PC12 CELLS

Perry T, Lahiri DK, Chen DM, Zhou J, Shaw KTY, Egan JM,Greig NH.

Journal of Pharmacology and Experimental Ther-apeutics 300: 958–966, 2002.

Reprinted with permissionfrom the American Society for Pharmacology and Experi-mental Therapeutics

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The insulinotropic hormone glucagon-like peptide-1 (7-36)-amide (GLP-1) has potent effects on glucose-dependent insulinsecretion, insulin gene expression, and pancreatic islet cellformation and is presently in clinical trials as a therapy for type 2diabetes mellitus. We report on the effects of GLP-1 and two ofits long-acting analogs, exendin-4 and exendin-4 WOT, on neu-ronal proliferation and differentiation, and on the metabolismof two neuronal proteins in the rat pheochromocytoma(PC12) cell line, which has been shown to express the GLP-1receptor. We observed that GLP-1 and exendin-4 inducedneurite outgrowth in a manner similar to nerve growth factor(NGF), which was reversed by coincubation with the selective

GLP-1 receptor antagonist exendin (9-39). Furthermore,exendin-4 could promote NGF-initiated differentiation and mayrescue degenerating cells after NGF-mediated withdrawal.

Neuropathy Abstracts Journal of the Peripheral Nervous System 7:205–212 (2002)

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These effects were induced in the absence of cellular dys-function and toxicity as quantitatively measured by 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lac-tate dehydrogenase assays, respectively. Our findings suggestthat such peptides may be used in reversing or halting theneurodegenerative process observed in neurodegenerativediseases, such as the peripheral neuropathy associated withtype 2 diabetes mellitus and Alzheimer’s and Parkinson’s dis-eases. Due to its novel twin action, GLP-1 and exendin-4 havetherapeutic potential for the treatment of diabetic peripheralneuropathy and these central nervous system disorders.

STRUCTURE OF CAMPYLOBACTER JEJUNI LIPOPOLYSACCHARIDES DETERMINES ANTIGANGLIOSIDE SPECIFICITY AND CLINICAL FEATURES OFGUILLAIN-BARRE, AND MILLER FISHER PATIENTS

Ang CW, Laman JD, Willison HJ, Wagner ER, Endtz HP,De Klerk MA, Tio-Gillen AP, Van den Braak N, Jacobs BC,Van Doorn PA.

Infection and Immunity 70: 1202–1208,2002.

Reprinted with permission from the American Societyfor Microbiology

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Ganglioside mimicry in the lipopolysaccharide (LPS) frac-tion of Campylobacter jejuni isolated from Guillain-Barré syn-drome (GBS) and Miller Fisher syndrome (MFS) patients wascompared with isolates from patients with an uncomplicatedenteritis. The antibody response to C. jejuni LPS and ganglio-sides in neuropathy patients and controls was compared aswell. LPS from GBS and MFS-associated isolates more fre-quently contained ganglioside-like epitopes compared to con-trol isolates. Almost all neuropathy patients showed a strongantibody response against LPS and multiple gangliosides incontrast to enteritis patients. Isolates from GBS patients morefrequently had a GM1-like epitope than isolates from MFS pa-tients. GQ1b-like epitopes were present in all MFS-associatedisolates and was associated with anti-GQ1b antibody reactivityand the presence of oculomotor symptoms. These resultsdemonstrate that the expression of ganglioside mimics is a riskfactor for the development of post-Campylobacter neuropathy.This study provides additional evidence for the hypothesis thatthe LPS fraction determines the antiganglioside specificity andclinical features in post-Campylobacter neuropathy patients.

CRYOGLOBULINS

Ferri C, Zignego AL, Pileri SA.

Journal of Clinical Pathol-ogy 55: 4–13, 2002.

Reprinted with permission from BritishMedical Journal Publishing Group

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Serum cryoglobulins are found in a wide spectrum ofdisorders but are often transient and without clinical implica-tions. Monoclonal cryoglobulins are usually associated withhaematological disorders, whereas mixed cryoglobulins arefound in many infectious and systemic disorders. So calledessential mixed cryoglobulinaemia shows a striking associationwith hepatitis C virus (HCV) infection (

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90%). It is a systemicvasculitis (leucocytoclastic vasculitis) with cutaneous and multi-ple visceral organ involvement. Chronic HCV infection canlead to a constellation of autoimmune and neoplastic disorders.In this review, the aetiology, diagnosis, disease heterogeneity,and treatment of cryoglobulinaemia are discussed.

IMMUNOLOGICAL STUDY OF HEREDITARY MOTOR AND SENSORY NEUROPATHY TYPE 1 A (HMSN1 A)

Gabriel CM, Gregson NA, Wood NW, Hughes RAC.

Jour-nal of Neurology Neurosurgery and Psychiatry 72: 230–235,2002.

Reprinted with permission from British Medical Jour-nal Publishing Group

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Objectives: Fifty three patients were studied to investigatewhether autoimmune or inflammatory mechanisms could ex-plain the phenotypic heterogeneity of patients with hereditarymotor and sensory neuropathy type 1a (HMSN1a). Methods:Serum samples were examined for antibodies to peripheralnerve myelin protein 22 (PMP22), ganglioside GM1 and caudaequina homogenate, and interleukin-6 (IL-6) and soluble tumournecrosis factor receptor 1 (sTNF R1) concentrations. Serologi-cal results were compared with those from patients with otherneuropathies (ONPs, n

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30) and with normal subjects (n

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51).Results: In the group as a whole, no relation emerged betweenclinical severity and any immune parameters. Immunohis-tochemical examination of four sural nerve biopsies did notshow significant inflammatory infiltration. In a subset of 12 pa-tients who experienced stepwise progression of disease, therewas a trend towards a higher proportion having anti-PMP22 an-tibodies (33% v 15% of those with gradual disease progres-sion, 3% ONPs, and no normal controls) and complement fix-ing antibodies to human cauda equina (25% v 5% with gradualprogression, 8.6% ONPs, 3.9% normal controls, p

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0.07).Conclusions: Patients with HMSN1a and a stepwise diseaseprogression may have an inflammatory, autoimmune compo-nent superimposed on the genetic condition.

DIFFERENTIAL AGGREGATION OF THE TREMBLER AND TREMBLER J MUTANTS OF PERIPHERAL MYELIN PROTEIN 22

Tobler AR, Liu N, Mueller L, Shooter EM.

Proceedings of theNational Academy of Sciences of the United States of Amer-ica 99: 483–488, 2002.

Reprinted with permission from theNational Academy of Sciences

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Mutations in the gene encoding the peripheral myelinprotein 22 (PMP22), a tetraspan protein in compact peripheralmyelin, are one of the causes of inherited demyelinating periph-eral neuropathy. Most PMP22 mutations alter the trafficking ofthe PMP22 protein in Schwann cells, and this different traf-ficking has been proposed as the underlying mechanism ofthe disease. To explore this problem further, we compared theaggregation of wild-type Pmp22 with those of the two Pmp22mutations found in Trembler (Tr) and Trembler J (TrJ) mice. Allthree Pmp22s can be crosslinked readily as homodimers intransfected cells. Wild-type Pmp22 also forms heterodimerswith Tr and TrJ Pmp22, and these heterodimers traffic withtheir respective mutant Pmp22 homodimers. All three Pmp22sform complexes larger than dimers with Tr Pmp22 especiallyprone to aggregate into high molecular weight complexes.Despite the differences in aggregation of Tr and TO Pmp22,these two mutant Pmp22s sequester the same amount ofwild-type Pmp22 in heterodimers and heterooligomers. Thus,the differences in the phenotypes of Tr and TrJ mice may de-pend more on the ability of the mutant protein to aggregatethan on the dominant-negative effect of the mutant Pmp22 onwild-type Pmp22 trafficking.


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NERVE GRANULOMAS AND VASCULITIS IN SARCOID PERIPHERAL NEUROPATHY - A CLINICOPATHOLOGICAL STUDY OF 11 PATIENTS

Said G, Lacroix C, Plante-Bordeneuve V, Le Page L, Pico F,Presles O, Senant J, Remy P, Rondepierre P, Mallecourt J.

Brain 125: 264–275, 2002.

Reprinted with permission fromOxford University Press

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Peripheral neuropathy is a rare, yet treatable manifesta-tion of sarcoidosis, a multisystem disorder characterized bythe presence of non-caseating granulomas that are seldomfound in nerve biopsy specimens. In order to learn more aboutthe subject, we reviewed our clinical and pathological findingsin a series of 11 patients (six men and five women aged 26-83years) with symptomatic neuropathy associated with charac-teristic granulomas in nerve biopsy specimens. Only two pa-tients were known to have sarcoidosis before the occurrenceof the neuropathy. The neuropathy was focal or multifocal in sixpatients, including one with a multifocal neuropathy associatedwith conduction blocks, and one with a multifocal axonal motordeficit. Four patients had a distal symmetrical deficit and onepatient had a Guillain-Barré-like syndrome with facial diplegiaand respiratory failure. Serum angiotensin-converting enzymeconcentration was elevated in only two patients. Epineurialgranulomas and perineuritis were present in all nerve speci-mens. The inflammatory infiltrates invaded the endoneurium,following connective tissue septae and blood vessels, in fivepatients. Multinucleated giant cells were found in eight patientsand necrotizing vasculitis in seven. Inflammatory lesions wereassociated with variable, asymmetrical involvement of nervefascicles and axon loss. A muscle specimen was sampledduring the same procedure in 10 patients. It showed inflamma-tory infiltrates and granulomas in nine patients and necrotizingvasculitis in two. Immunolabeling showed a mixed inflamma-tory infiltrate of T cells (predominantly CD4

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cells) and mac-rophages, in keeping with a delayed hypersensitivity reaction.In addition to nerve involvement, all patients had at least oneother tissue or organ affected, including muscle in nine pa-tients, lungs and/or intrathoracic lymph nodes in eight, skin inthree, arthritis in two, and peripheral lymph nodes, stomachand eye in one patient each. Most patients improved on cor-ticosteroids. Two patients remain free of symptoms after 7years. Severe side-effects of long-term treatment with cortico-steroids occurred in two patients, leading to death in one. Thisstudy illustrates the wide range of clinical manifestations ofsarcoid neuropathy and the frequent association of granuloma-tous inflammatory infiltrates with necrotizing vasculitis andwith silent or symptomatic involvement of other organs.

PARANEOPLASTIC PERIPHERAL NEUROPATHY ASSOCIATED WITH ANTI-HU ANTIBODIES. A CLINICAL AND ELECTROPHYSIOLOGICAL STUDY OF 20 PATIENTS

Camdessanche JP, Antoine JC, Honnorat J, Vial C, PetiotP, Convers P, Michel D.

Brain 125: 166–175, 2002.

Reprintedwith permission from Oxford University Press

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Although paraneoplastic subacute sensory neuronopa-thy is the most frequent presentation of peripheral neuropa-thy in patients with anti-Hu antibodies, other neuropathieshave been reported. In order to investigate the clinical andelectrophysiological manifestations of neuropathies associated

with anti-Hu antibodies, we conducted a retrospective studyof 20 patients. For the electrophysiological study, each nervewas classified as normal, demyelinating, axonal/neuronal oraxonal/ demyelinating. Peripheral neuropathy was the pre-senting symptom in 95% of patients. CNS and autonomicneuropathy were present in 40% and 30% of patients, respec-tively. The course of the neuropathy was acute, mimickingGuillain-Barré syndrome in one patient (5%), and subacute(55%) or progressive (40%) in the others. Clinically, the neu-ropathy was sensory (70%), sensorimotor (25%) or motor(5%). At onset, symptoms were symmetrical (65%), asym-metrical (25%) or multifocal (10%). Pain was a predominantmanifestation (80%). Amyotrophia and fasciculations wererare. The median Rankin’s score was 2, three patients havingan indolent form. Electrophysiology showed the axonal/neu-ronal pattern to be the most frequent (46.9% of studiednerves); an axonal/demyelinating or demyelinating patternbeing seen in 18.3% and 4.9% of nerves, respectively. Theaxonal/neuronal pattern was more frequent in sensorynerves and the mixed axonal/demyelinating pattern morefrequent in motor nerves (P

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0.01). A higher proportion ofabnormal nerves correlated with a progressive course (P

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0.05) or a Rankin’s score between 3 and 5 (P

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0.01). In pa-tients with sensory neuropathy, 88.5% of sensory nerveswere abnormal, mostly with an axonal/neuronal pattern. Inaddition, 47% of motor nerves were abnormal so that onlyfour out of 14 patients with a clinically pure sensory neuro-pathy (28.6%) had an electrophysiological pattern typical ofsensory neuronopathy. In patients with a sensorimotor neuro-pathy, 96.6% of sensory and 71% of motor nerves were ab-normal. The only statistical difference between sensory andsensorimotor neuropathies was that patients with sensorim-otor neuropathy had more frequent motor nerve involve-ment (P

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0.05) without differences concerning the distribu-tion of the abnormal patterns. Needle neuromyographyshowed only limited evidence of motor neurone degenera-tion in both sensory and sensorimotor neuropathy. Thepresent work shows that the typical clinical and electrophys-iological pattern of subacute sensory neuronopathy is rarelyencountered in patients with anti-Hu antibody and that motornerve involvement is frequently seen, even in the absenceof a motor deficit. In addition to their potential pathophysiologi-cal involvement in the mechanism of the paraneoplastic neu-ropathy, these findings have practical consequences for thediagnosis of the disorder.

BURST DISCHARGE IN PRIMARY SENSORY NEURONS: TRIGGERED BY SUBTHRESHOLD OSCILLATIONS, MAINTAINED BY DEPOLARIZING AFTERPOTENTIALS

Amir R, Michaelis M, Devor M.

Journal of Neuroscience22: 1187–1198, 2002.

Reprinted with permission from theSociety for Neuroscience

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Afferent discharge generated ectopically in the cellsoma of dorsal root ganglion (DRG) neurons may play a rolein normal sensation, and it contributes to paraesthesias andpain after nerve trauma. This activity is critically dependenton subthreshold membrane potential oscillations; oscillatorysinusoids that reach threshold trigger low-frequency trains ofintermittent spikes. Ectopic firing may also enter a high-


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frequency bursting mode, however, particularly in the eventof neuropathy. Bursting greatly amplifies the overall ectopicbarrage. In the present report we show that subthresholdoscillations and burst discharge occur in vivo, as they do invitro. We then show that although the first spike in eachburst is triggered by an oscillatory sinusoid, firing withinbursts is maintained by brief regenerative post-spike depo-larizing afterpotentials (DAPs). Numerical simulations wereused to identify the cellular process underlying reboundDAPs, and hence the mechanism of the spike bursts. Finally,we show that slow ramp and hold (tonic) depolarizations ofthe sort that occur in DRG neurons during physiologically rel-evant events are capable of triggering sustained ectopicbursting, but only in cells with subthreshold oscillatory be-havior. Oscillations and DAPs are an essential substrate ofectopic burst discharge. Therefore, any consideration of theways in which cellular regulation of ion channel synthesisand trafficking implement normal sensation and, when dis-rupted, bring about neuropathic pain must take into accountthe effects of this regulation on oscillations and bursting.

ORALLY-EFFECTIVE, LONG-ACTING SORBITOL DEHYDROGENASE INHIBITORS: SYNTHESIS, STRUCTURE-ACTIVITY RELATIONSHIPS, AND IN VIVO EVALUATIONS OF NOVEL HETEROCYCLE-SUBSTITUTED PIPERAZINO-PYRIMIDINES

Chu-Moyer MY, Ballinger WE, Beebe DA, Berger R,Coutcher JB, Day WW, Li JC, Mylari BL, Oates PJ, WeeklyRM.

Journal of Medicinal Chemistry 45: 511–528, 2002.

Reprinted with permission from the American ChemicalSociety

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Optimization of a previously disclosed sorbitol dehydroge-nase inhibitor (SDI, II) for potency and duration of action wasachieved by replacing the metabolically labile N,N-dimethylsul-famoyl group with a variety of heterocycles. Specifically, this ef-fort led to a series of novel, in vitro potent SDIs with longer se-rum half-lives and acceptable in vivo activity in acutely diabeticrats (e.g., 62, 67, and 69). However, the desired in vivo potencyin chronically diabetic rats, ED90 less than or equal to 5 mg/kg/day, was achieved only through further modification of the pip-erazine linker. Several members of this family, including 86,showed better than the targeted potency with ED90 values of1-2 mg/kg/day. Compound 86 was further profiled and found tobe a selective inhibitor of sorbitol dehydrogenase, with excel-lent pharmacodynamic/pharmacokinetic properties, demon-strating normalization of sciatic nerve fructose in a chronicallydiabetic rat model for approximately 17 h, when administeredorally at a single dose of 2 mg/kg/day.

CHRONIC ARSENIC POISONING FROM BURNING HIGH-ARSENIC-CONTAINING COAL IN GUIZHOU, CHINA

Liu J, Zheng BS, Aposhian HV, Zhou YS, Chen ML, ZhangAH, Waalkes MP.

Environmental Health Perspectives 110: 119–122, 2002.

Reprinted with permission from the US Departmentof Health and Human Sciences, Public Health Science

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Arsenic is an environmental hazard and the reduction ofdrinking water arsenic levels is under consideration. People

are exposed to arsenic not only through drinking water butalso through arsenic-contaminated air and food. Here we re-port the health effects of arsenic exposure from burning higharsenic-containing coal in Guizhou, China. Coal in this regionhas undergone mineralization and thus produces high con-centrations of arsenic. Coal is burned inside the home inopen pits for daily cooking and crop drying, producing a highconcentration of arsenic in indoor air. Arsenic in the air coatsand permeates food being dried producing high concentra-tions in food; however, arsenic concentrations in the drinkingwater are in the normal range. The estimated sources of to-tal arsenic exposure in this area are from arsenic-contami-nated food (50-80%), air (10-20%), water (1-5%), and directcontact in coal-mining workers (1%). At least 3,000 patientswith arsenic poisoning were found in the Southwest Prefec-ture of Guizhou, and approximately 200,000 people are atrisk for such overexposures. Skin lesions are common, in-cluding keratosis of the hands and feet, pigmentation on thetrunk, skin ulceration, and skin cancers. Toxicities to internalorgans, including lung dysfunction, neuropathy, and nephro-toxicity, are clinically evident. The prevalence of hepatome-galy was 20%, and cirrhosis, ascites, and liver cancer are themost serious outcomes of arsenic poisoning. The Chinesegovernment and international organizations are attemptingto improve the house conditions and the coal source, andthereby protect human health in this area.

DISTINCT PATTERN OF AGE-SPECIFIC INCIDENCE OF GUILLAIN-BARRE SYNDROME IN HARBIN, CHINA

Cheng Q, Wang DS, Jiang GX, Han H, Zhang Y, Wang WZ,Fredrikson S.

Journal of Neurology 249: 25–32, 2002.

Reprinted with permission from Dr. Dietrich Steinkopff Verlag

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We describe the age- and sex-specific incidence of Guil-lain-Barré syndrome (GBS) in Harbin, China, based on the in-formation from a prospective survey among a well-definedlarge population during one year. A network of physicians re-ported incident patients with a GBS diagnosis from a generalpopulation of 5.4 million inhabitants in Harbin, China, duringthe period from 1 October 1997 to 30 September 1998. Eachreported patient was examined by senior neurologists andthe GBS diagnosis was validated according to standard diag-nostic criteria. All GBS patients were followed-up for sixmonths after onset. Admission registers at all hospitals inHarbin were also checked afterwards for screening patientswith a GBS diagnosis who might have been missed. Duringthe study period, 79 patients with a GBS diagnosis were re-ported. After validation, the GBS diagnosis was confirmed in70 patients. Another GBS patient was found through thescreening of admission registers at hospitals. Among them,36 GBS patients were residents in Harbin and the other 35patients were from geographical areas out of Harbin. TheGBS incidence, age-adjusted to the European standard pop-ulation, was 0.66 (95% CI 0.46-0.91) per 100,000 person-years, with a male to female ratio of 1.4. The highest GBSincidence was found in the youngest age-group and the inci-dence among the elderly was remarkably lower than thosereported from other populations in Western countries. Possi-ble explanations for the distinct pattern of age-specific inci-dence of GBS are discussed. Further studies are needed.


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VOLTAGE OPENS UNOPPOSED GAP JUNCTION HEMICHANNELS FORMED BY A CONNEXIN 32 MUTANT ASSOCIATED WITH X-LINKED CHARCOT-MARIE-TOOTH DISEASE

Abrams CK, Bennett MVL, Verselis VK, Bargiello TA.

Pro-ceedings of the National Academy of Sciences of the UnitedState of America 99: 3980–3984, 2002.

Reprinted with per-mission from the National Academy of Sciences

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The X-linked form of Charcot-Marie-Tooth disease(CMTX) is an inherited peripheral neuropathy that arises inpatients with mutations in the gene encoding the gap junc-tion protein connexin 32 (Cx32), which is expressed bySchwann cells. We recently showed that Cx32 containingthe CMTX-associated mutation, Ser-85-Cys (S85C), formsfunctional cell-cell channels in paired Xenopus oocytes.Here, we describe that this mutant connexin also shows in-creased opening of hemichannels in nonjunctional surfacemembrane. Open hemichannels may damage the cellsthrough loss of ionic gradients and small metabolites and in-creased influx of Ca

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, and provide a mechanism by whichthis and other mutant forms of Cx32 may damage cells inwhich they are expressed. Evidence for open hemichannelsincludes: (i) oocytes expressing the Cx32(S35C) mutantshow greatly increased conductance at inside positive po-tentials, significantly larger than in oocytes expressing wild-type Cx32 (Cx32WT); and (ii) the induced currents are similarto those previously described for several other connexinhemichannels, and exhibit slowly developing increases withincreasing levels of positivity and reversible reduction whenintracellular pH is decreased or extracellular Ca

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concentra-tion is increased. Although increased currents are seen, oo-cytes expressing Cx32(S35C) have lower levels of the pro-tein in the surface and in total homogenates than do oocytesexpressing Cx32WT; thus, under the conditions examinedhere, hemichannels in the surface membrane formed of theCx32(S85C) mutant have a higher open probability thanhemichannels formed of Cx32WT. This increase in functionalhemichannels may damage Schwann cells and ultimatelylead to loss of function in peripheral nerves of patients har-boring this mutation.

SALVAGE THERAPY WITH THALIDOMIDE IN PATIENTS WITH ADVANCED RELAPSED/REFRACTORY MULTIPLE MYELOMA

Tosi P, Zamagni E, Cellini C, Ronconi S, Patriarca F, Bal-lerini F, Musto P, Di Raimondo F, Ledda A, Lauria F, MasiniL, Gobbi M, Vacca A, Ria R, Cangini D, Tura S, BaccaraniM, Cavo M.

Haematologica 87: 408–414, 2002.

Reprintedwith permission from the Ferrata Storti Foundation

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Background and Objectives. Few therapeutic optionsare presently available for patients with multiple myeloma(MM) who relapse after autologous or allogeneic stem celltransplantation, or for patients who are refractory to conven-tional chemotherapy and not eligible for salvage high-dosetherapy. Thalidomide, a glutamic acid derivative with anti-an-giogenic properties, has been recently proposed as an effec-tive therapy for patients with advanced refractory disease.The aim of this study was to evaluate the activity of thalido-mide in a large series of MM patients. Design and Methods.

From October 1999 to January 2001, 65 patients (46 males/19 females) from 8 Italian institutions were treated with tha-lidomide. Twenty-six patients had relapsed after autologousstem cell transplantation, either single (n

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12) or double(n

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12); 38 patients had shown disease progression aftergreater than or equal to 2 lines of conventional chemother-apy, 2 patients had relapsed after allotransplant, one singlepatient had not received previous treatment. Sixty-one(93.8%) patients were in stage 111, median beta2 micro-globulin was 2.9 mg/L, and median bone marrow plasma cellinfiltration was 50%. Thalidomide was initially administeredat a dose of 100 mg/day; if well tolerated, the dose was tobe increased serially by 200 mg every other week to a maxi-mum of 800 mg/day. Results. The median administereddose of thalidomide was 400 mg/day. WHO grade

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II toxiceffects were constipation (52%), lethargy (34%), skin rash(11%), peripheral neuropathy (14%) and leukopenia (3%).Sixty patients are presently evaluable for response; of these,17 (28.3%) showed greater than or equal to 50% reductionin serum or urinary M protein concentration and 11 (18.3%)showed greater than or equal to 25% tumor reduction, for atotal response rate averaging 46.6%. After a median of 8months’ follow-up, 15/28 patients are alive and progression-free(at 2 to 16 months), 12 patients have relapsed, and 1 patientdied of pulmonary edema while still in partial remission. Amongpre-treatment variables that were analyzed for their potentialrelationship with tumor response, only the concentration ofvascular endothelial growth factor (VEGF) in the conditionedmedia obtained upon culture of bone marrow plasma cellswas statistically significant. Plasma cells from patients whoresponded favorably to thalidomide secreted a significantlylower amount of VEGF than plasma cells from resistantpatients (126.45

165 pg/mL vs 227.11

70 pg/mL, p

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0.04). Interpretation and Conclusions. These data confirm thatthalidomide is active in patients with advanced relapsed/ re-fractory MM and represent the basis for ongoing clinical tri-als aimed at testing the role of this drug as front line therapy fornewly diagnosed disease.

AGE-RELATED SYMPATHETIC GANGLIONIC NEUROPATHOLOGY: HUMAN PATHOLOGY ANDANIMAL MODELS

Schmidt RE.

Autonomic Neuroscience – Basic & Clinical96: 63–72, 2002.

Reprinted with permission from ElsevierScience BV

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Systematic studies of the autonomic nervous system ofhuman subjects and development of well-defined animalmodels have begun to substantially improve our understandingof the pathogenesis of autonomic dysfunction in aging andmay eventually provide strategies for intervention. Neuropatho-logical studies of the sympathetic ganglia of aged humansubjects and rodent models have demonstrated that neu-roaxonal dystrophy involving intraganglionic terminal axonsand synapses is a robust, unequivocal and consistent neuro-pathological finding in the aged sympathetic nervous systemof man and animals. Quantitative studies have demonstratedthat markedly swollen argyrophilic dystrophic axon terminalsdevelop in the prevertebral superior mesenteric (SMG) andcoeliac, but to a much lesser degree in the superior cervical


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ganglia (SCG) as a function of age, sex (males more than fe-males) and diabetes. Dystrophic axons were immunoreactivefor neuropeptide Y, tyrosine hydroxylase, dopamine-beta-hydroxylase, trkA and p75(NTR), an immunophenotype con-sistent with their origin from postganglionic sympathetic neu-rons, and contained large numbers of highly phosphorylatedneurofilaments or tubulovesicular elements. The sympatheticganglia of aged rodents also showed the hallmark changesof neuroaxonal dystrophy as a function of age and location(many more in the SMG than in the SCG). Plasticity-relatedsynaptic remodeling could represent a highly vulnerable targetof the aging process. The fidelity of animal models to theneuropathology of aged humans suggests that similar pathoge-netic mechanisms may be involved in both and that therapeuticadvances in animal studies may have human application.

THERMOSENSITIVITY OF LARGE PRIMARYSENSORY NEURONS

Li HQ, Liu BG, Dobretsov M, Brull SJ, Zhang JM.

BrainResearch 926: 18–26, 2002.

Reprinted with permission fromElsevier Science BV

.

Spontaneous activity originating in the injured nerve or thedorsal root ganglion (DRG) has been implicated in the develop-ment and maintenance of neuropathic pain. The inherent char-acteristics of spontaneous activity and the causal factors thatmodulate its firing pattern and frequency are not fully under-stood. We attempted to assess the thermosensitivity ofspontaneous activity in dorsal root ganglion (DRG) neuronsin normal rats and in rat, with cl-ironic compression of the DRG(CCD) in an in vitro nerve-DRG preparation. Extracellular, dorsalroot recording from 66 spontaneously active CCD Abeta fibersindicate that: (1) decreasing bath temperature from 37 to 36-26

C significantly decreased the firing rate (FR) in 85% (56/66) offibers tested, of which 19 fibers (34%) responded to tempera-ture change at physiological range (36-37

C), whereas the re-maining fibers responded at lower temperature levels (26-36

C); (2) cooling of the DRG increased the FR in 12% (8/66) of fi-bers tested; (3) similarly, the firing rate of 21/26 spontaneouslyactive Abeta fibers from normal rats was decreased followingtemperature decrease; (4) intracellular recordings from 38 nor-mal neurons revealed that cooling the DRG significantly in-creased the action potential (AP) threshold, A-P duration, APamplitude and afterhyperpolarization (AHP) duration, but de-creased AHP amplitude, maximal depolarizing and repolarizingrates. There was no significant change in the rheobase cur-rents or the resting membrane potential. The present studyindicates that large sensory neurons with myelinated axons aretemperature dependent. It also suggests that maintenance of astable temperature is critical for reliable characterization ofspontaneous activity of sensory neurons.

MACROPHAGE-RELATED DEMYELINATION IN PERIPHERAL NERVES OF MICE DEFICIENT IN THE GAP JUNCTION PROTEIN CONNEXIN 32

Kobsar I, Maurer M, Ott T, Martini R.

Neuroscience Letters320: 17–20, 2002.

Reprinted with permission from ElsevierScience Ireland, Ltd

.

Mice deficient in the gap junction protein connexin 32(Cx32) develop a slowly progressing demyelinating neuropa-thy, with enlarged periaxonal collars, abnormal non-com-pacted myelin domains and axonal sprouts. These miceserve as a model for the X-linked form of inherited demyelin-ating neuropathies in humans. Based on our previous find-ings that macrophages are involved in demyelination in othermyelin mutants (i.e. mice heterozygously deficient in P0),we considered the possibility that macrophages might bealso mediators of demyelination in Cx32-deficient mice. In-deed, we detected an age-related increase in the number ofmacrophages in demyelinating nerves of Cx32-deficient mice.In addition, immunoelectron microscopy revealed macro-phages in an apposition to degenerating myelin reminiscentof a macrophage-mediated demyelinating neuropathy. Weconclude that involvement of macrophages might be a wide-spread phenomenon in genetically-determined demyelination.

ANTEROGRADE TNF

�

TRANSPORT FROM RAT DORSAL ROOT GANGLION TO SPINAL CORD AND INJURED SCIATIC NERVE

Shubayev VI, Myers RR.

Neuroscience Letters 320: 99–101, 2002.

Reprinted with permission from Elsevier ScienceIreland, Ltd

.

Tumor necrosis factor-

�

(TNF

�

) is a key modulator ofpainful peripheral nerve injury. We have previously shownthat a tracer of TNF

�

injected at the site of rat sciatic nerveinjury undergoes retrograde axonal transport to the dorsalroot ganglia (DRG). To further understand the role of TNF

�

inDRG, we injected rat L5 DRG with biotinylated TNF

�

, neuro-biotin, or vehicle, and detected translocation of the biotin tagby avidin-biotin histochemistry. Biotinylated TNF

�

was trans-ported intraaxonally toward the periphery of both normal andinjured nerves. It also reached the dorsal horn of the spinalcord in injured rats, but not in control rats. These findingshighlight a dynamic process of TNF

�

axonal transport in theperipheral neural axis, and help explain activation of centralcytokines in the pathogenesis of painful neuropathy.

RESPONSE CHARACTERISTICS OF CUTANEOUS MECHANORECEPTORS IN NEUROPATHIC RATS

Bulka A, Hao JX, Wiesenfeld-Hallin Z.

Neuroscience Let-ters 317: 89–92, 2002.

Reprinted with permission fromElsevier Science Ireland, Ltd

.

The activity of single myelinated afferents was recordedfrom dorsal roots L4-5 in normal Sprague-Dawley rats andanimals that developed mechanical hypersensitivity follow-ing ischemic injury to the sciatic nerve. The mechanical re-sponse properties and conduction velocity of afferents con-ducting through the injury site (about 50% of units) weresimilar to controls. However, the majority of afferents notconducting through the injury site exhibited ongoing activity.The results suggest that mechanical allodynia may be atleast partly due to the central integration of activity arisingfrom these two populations of afferents in neuropathic rats.


211

AUTOMATED AND REPRESENTATIVE FASCICLE SELECTION FOR COMPUTER-ASSISTED MORPHOMETRY OF MYELINATED NERVE FIBRES IN PERIPHERAL NERVES

Lindemuth R, Mink D, Ernzerhof C, Schimrigk K.

Comput-ers in Biology and Medicine 32: 1–11, 2002.

Reprinted withpermission from Pergamon-Elsevier Science, Ltd

.

We describe an algorithm that permits representativefascicle selection for sample acquisition from the entire cross-section of a nerve. We calculate the number of fasciclesnecessary for the acquisition of a given sample volume ofnerve fibres from the image magnification, determine thescheme of intrafascicular sampling, and measure the (esti-mated) nerve fibre density. We start by storing the positionsof all fascicles as coordinates of the microscope motor stage.We then recruit the needed fascicles from the file by callingthem up out of the storage order with a constant interval,using the quotient of the total number of fascicles and thenumber of fascicles necessary to obtain the sample size forthis purpose. The results obtained on the analysis of 40specimens of sural and tibial nerves by means of the imageanalysis system IBAS are reported.

CHRONIC SENSORY NEURONOPATHY ASSOCIATED WITH HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE I INFECTION

Shimazaki R, Ueyama H, Mori T, Mori M, Fujimoto S,Kumamoto T, Tsuda T.

Journal of the Neurological Sci-ences 194: 55–58, 2002.


.

We described two patients with chronic sensory neuron-opathy who had anti-HTLV-I antibody in serum and cere-brospinal fluid but no signs of myelopathy, A sural nervespecimen revealed severe degeneration of myelinated andunmyelinated axons. The second patient had subclinicalSjogren’s syndrome suggestive of a possible link among hu-man T-cell lymphotropic virus type I (HTLV-I), Sjogren’s syn-drome and sensory neuronopathy, respectively. The broadspectrum of neurologic disorders associated with HTLV-Tinfection now would include chronic sensory neuronopathy.

A FAMILY WITH AUTOSOMAL DOMINANT MUTILATING NEUROPATHY NOT LINKED TO EITHER CHARCOT-MARIE-TOOTH DISEASE TYPE 2B (CMT2B) OR HEREDITARY SENSORY NEUROPATHY TYPE I (HSN I) LOCI

Bellone E, Rodolico C, Toscano A, Di Maria E, CassandriniD, Pizzuti A, Pigullo S, Mazzeo A, Macaione V, Girlanda P,Vita G, Ajmar F, Mandich P.

Neuromuscular Disorders 12:286–291, 2002.

Reprinted with permission from Pergamon-Elsevier Science, Ltd

.

Sensory loss and ulcero-mutilating features have beenobserved in hereditary sensory neuropathy type I and in her-editary motor and sensory neuropathy type IIB, also referredas Charcot-Marie-Tooth disease type 2B. To date two loci asso-ciated with ulcero-mutilating, neuropathy have been described:CMT2B at 3q13-q22 and HSN I at 9q22.1-q22.3. We performedlinkage analysis with chromosomal markers representing thehereditary sensory neuropathy type I and Charcot-Marie-Toothdisease type 213 loci on an Italian family with a severe distalsensory loss leading to an ulcero-mutilating peripheral neuropa-

thy. Negative likelihood-of-odds scores excluded any evidenceof linkage to both chromosome 3q13 and chromosome 9q22markers, confirming the genetic heterogeneity of this clinicalentity and the presence of a third locus responsible for ulcero-mutilating neuropathies.

GCPII (NAALADase) INHIBITION PREVENTS LONG-TERM DIABETIC NEUROPATHY IN TYPE 1 DIABETICBB/WOR RATS

Zhang W, Slusher B, Murakawa Y, Wozniak KM, Tsuka-moto T, Jackson PF, Sima AAF.

Journal of the NeurologicalSciences 194: 21–28, 2002.


.

Aims/Hypothesis: Hyperglutamatergic activity induced byischemia is believed to underlie neuronal damage in a varietyof neurological disorders, including neuropathic pain. Sinceischemia is believed to be a prominent mechanism involvedin diabetic polyneuropathy (DPN), we investigated the effectof the glutamate carboxypeptidase II (GCPII, EC #3.4.17.21;previously termed NAALADase), an enzyme responsible forthe hydrolysis of the neuropeptide NAAG to NAA andglutamate, on the development of DPN in type 1 diabeticBB/Wor rats. Methods: Diabetic animals were treated with10 mg/kg/day i.p. of the selective GCPII inhibitor GPI-5232from onset of diabetes for 6 months. Hyperalgesia to thermalstimulation and nerve conduction velocity (NCV)) were mea-sured monthly. The effect on structural DPN was assessedby scoring of single, teased myelinated fibers, myelinated fibermorphometry and ultrastructural examination of C-fibers at 6months. Results: GCPII inhibition showed significant but partialeffects on hyperalgesia (p

�

0.001), nerve conduction slowing(p

�

0.01), axonal and nodal structural changes (p

�

0.001),small myelinated fiber atrophy, and degenerative changes ofC-fibers. Conclusions: GCPII inhibition has beneficial effectson hyperalgesia, nerve function, and structural degenerativechanges in DPN, which are likely mediated by inhibition ofischemia-induced glutamate release.

THE MITOCHONDRIAL GENOME AND HUMAN MITOCHONDRIAL DISEASES

Sukernik RI, Derbeneva OA, Starikovskaya EB, VolodkoNV, Mikhailovskaya IE, Bychkov IY, Lott M, Brown M,Wallace D.

Russian Journal of Genetics 38: 105–113, 2002.

Reprinted with permission from Kluwer Academic/PlenumPublishers

.

To date, more than 100 point mutations and severalhundreds of structural rearrangements of mitochondrial DNA(mtDNA) are known too be connected with characteristicneuromuscular and other mitochondrial syndromes varyingfrom those causing death at the neonatal stage to diseaseswith late ages of onset. The immediate cause of mitochondrialdisorders is a defective oxidative phosphorylation. Wide phe-notypic variation and the heteroplasmy phenomenon, whichsome authors include in mutation load, are characteristic ofhuman mitochondrial diseases. As the numbers of casesidentified and pedigrees described increase, data on thegenotype-phenotype interaction and the structure and fre-quency of pathogenic and conditionally pathogenic mtDNA


212

mutations in human populations are rapidly accumulated.The data on the genetics and epidemiology of mitochondrialdiseases are not only important for differential diagnosis andgenetic counseling. Since both neutral and mildly patho-genic mutations of mtDNA are progressively accumulated inmaternal phyletic lines, molecular analysis of these muta-tions permits not only reconstruction of the genealogicaltree of modern humans, but also estimation of the role thatthese mutations play in natural selection.

CHARACTERIZATION OF A DELTA- AND C-FIBERS INNERVATING THE PLANTAR RAT HINDPAW ONE DAY AFTER AN INCISION

Pogatzki EM, Gebhart GF, Brennan TJ.

Journal of Neuro-physiology 87: 721–731, 2002.

Reprinted with permissionfrom the American Physiological Society

.

Primary hyperalgesia after tissue injury is suggested toresult from sensitization of primary afferent fibers, but sensi-tization to mechanical stimuli has been difficult to demon-strate. In the companion study, sensitization of mechano-re-sponsive Adelta- and C-fibers did not explain pain behaviors45 min after an incision in the rat hindpaw. In the presentstudy, we examined mechanical response properties ofAdelta- and C-fibers innervating the glabrous skin of theplantar hindpaw in rats 1 day after an incision or sham proce-dure. In behavioral experiments, median withdrawal thresh-olds to von Frey filaments were reduced from 522 mN be-fore to 61 mN 2 and 20 h after incision; median withdrawalthresholds after sham procedure were stable (522 mN). Re-sponses to a nonpunctate mechanical stimulus were in-creased after incision. In neurophysiological experiments inthese same rats, 67 single afferent fibers were characterizedfrom the left tibial nerve 1 day after sham procedure (n

�

39)or incision (n

�

28); electrical stimulation was used as thesearch stimulus to identify a representative population ofAdelta- and C-fibers. In the incision group, 11 fibers (39%)had spontaneous activity with frequencies ranging from0.03 to 39.3 imp/s; none were present in the sham group.The median response threshold of Adelta- fibers was less inthe incision (56 mN, n

�

13) compared with sham (251 mN,n

�

26) group, mainly because the proportion of mechanicallyinsensitive afferents (MIAs) was less (8 vs. 54% after shamprocedure). Median C-fiber response thresholds were similar

in incised (28 mN, n

�

15) and sham rats (56 mN, n

�

13).Responsiveness to monofilaments was significantly enhancedin Adelta- fibers 1 day after incision; stimulus response func-

tions of C-fibers after incision and after sham procedure didnot differ significantly. Only Adelta- fibers but not C-fiberssensitized to the nonpunctate mechanical stimulus. The sizeof receptive fields was increased in Adelta- and C-fibers 1 dayafter incision. The results indicate that sensitization of Adelta-and C-fibers is apparent 1 day after incision. Because sensiti-zation of afferent fibers to mechanical stimuli correlated withbehavioral results, sensitization may contribute to the reducedwithdrawal threshold after incision. Spontaneous activity inAdelta- and C-fibers may account for nonevoked pain behaviorand may also contribute to mechanical hyperalgesia by am-plifying responses centrally.

SUBTHRESHOLD OSCILLATIONS INDUCED BY SPINAL NERVE INJURY IN DISSOCIATED MUSCLE AND CUTANEOUS AFFERENTS OF MOUSE DRG

Liu CN, Devor M, Waxman SG, Kocsis JD.

Journal of Neu-

rophysiology 87: 2009–2017, 2002

.

Reprinted

WITH

PERMISSIONFROM

THE

A

MERICAN

P

HYSIOLOGICAL

Society

.

Whole cell patch-clamp recordings were obtained fromdissociated mouse lumbar dorsal root ganglion (DRG) neu-rons. Recordings were made from control neurons and neu-rons axotomized by transection of the corresponding spinalnerve 1-2 days prior to dissociation. Medium to large muscleand cutaneous afferent neurons were identified by retro-grade transport of True Blue or Fluoro-Gold injected into thecorresponding peripheral tissue. Action potentials were clas-sified as non-inflected spikes (A(0)) and inflected spikes(A(inf)). High-frequency, low-amplitude subthreshold mem-brane potential oscillations were observed in 8% of controlA(0) neurons, but their incidence increased to 31% in thenerve injury group. Fifty percent of axotomized muscle affer-ent A(0) cells displayed oscillations, while 26% of axoto-mized cutaneous afferents exhibited oscillations. Lower-fre-quency oscillations were also observed in a small fraction(4%) of A(inf) neurons on strong depolarization. Their num-bers were increased after the nerve injury, but the differencewas not statistically significant. The oscillations often trig-gered burst firing in distinct patterns of action potential activ-ity. These results indicate that injury-induced membrane os-cillations of DRG neurons, previously observed in wholeDRG of rats, are present in dissociated DRG neurons of theadult mouse. Moreover, these observations indicate thatboth muscle and cutaneous afferents in the A(beta) sizerange give rise to injury-induced membrane oscillations, withmuscle afferents being more prone to develop oscillations.

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