Biomedical subjects

P Mercier

Publications and source records attributed to P Mercier.

At least 19 recordsLinked to original sources

PubMed2006

Mycoplasma mycoides subsp. mycoides biotype large colony isolates from healthy and diseased goats: prevalence and typing.

Most severe goat mycoplasmosis outbreaks in France are caused by Mycoplasma mycoides subsp. mycoides biotype LC (MmmLC). However, MmmLC can also be recovered from ear canals of healthy goats or from bulk milk collected in herds showing no clinical signs of mycoplasmosis. To improve our understanding of how MmmLC strains are balanced between pathogenic ones and asymptomatically carried ones, descriptive epidemiological data were analysed, together with the genomic fingerprints of isolates generated using pulsed-field gel electrophoresis (PFGE). PGFE analyses were performed with isolates collected from the ear canals of goats or bulk milk in healthy herds, from individual clinical cases in different diseased herds at different times, and within a single herd during a severe outbreak, from various body sites including the ear canals at autopsy. Results showed that each isolate collected in healthy herds yielded a unique and characteristic PFGE profile. Isolates from diseased herds had profiles that were distinct for each outbreak and the group of 41 isolates from a single severe outbreak had 2 predominant PFGE profiles that persisted throughout the outbreak. These data suggest that while several distinct isolates are carried by healthy animals, only a few are responsible for the clinical signs observed within one herd during an outbreak. Whether this reflects differences in virulence between different field strains of MmmLC remains to be demonstrated.

Animals↗

PubMed2006

Distribution of killer-cell immunoglobulin-like receptor (KIR) in Comoros and Southeast France.

Killer-cell immunoglobulin-like receptors (KIRs) expressed by natural killer cells are cell surface molecules able to recognize groups of HLA class I alleles. The number and distribution of KIR genes vary among individuals and populations. The aim of this study is to analyse the KIR gene content in a Comorian population in order to investigate genetic relationships with other populations and to reconstruct past migration events. The Comorian population consisted of 54 unrelated immigrants living in France and a control population consisted of 38 individuals from Southeast France. We investigated the presence or absence of 15 KIR genes, two pseudogenes expressed and non-expressed forms of KIR2DL5 and the two major subtype full-length and deleted forms of KIR2DS4. All individuals were typed positive for the framework genes, i.e. KIR2DL4, KIR3DL2 and KIR3DL3, and the two pseudogenes KIR3DP1 and KIR2DP1. The frequencies of full-length KIR2DS4 (*00101/00102/002) were lower in the French population (F = 29%) than in the Comorian population (F = 72%) (P(c) < 0.05). No significant differences were found for other KIR genes. A total of 11 genotypes were identified in the Southeast French population and 22 genotypes in the Comorian population. The most common genotype (2DL1, 2DL3, 2DL4, 3DL1, 3DL2, 3DL3 and 2DS4) accounted for 41% in the Comorian population and 34% in the Southeast French population. Principal component analysis using KIR gene data from 20 populations was performed to determine genetic differences and relations between populations. The Comorian population exhibited closest kinship with Africans and Asians. As KIR gene content is heterogeneous among ethnic groups, it can probably be used to assess the genetic relationships among populations from different geographic areas.

Comoros↗

PubMed2005

Supratentorial primitive neuroectodermal tumours of the brain: multidirectional differentiation does not influence prognosis. A clinicopathological report of 18 patients.

AIMS: To examine the clinical and pathological characteristics of supratentorial primitive neuroectodermal tumours (PNETs) in a retrospective series of 18 patients, according to the strict definition of the World Health Organization classification of tumours that excludes other types of malignant embryonal tumours of the brain. METHODS AND RESULTS: Eleven children and seven adults with supratentorial PNETs were diagnosed between 1993 and 2002 and their medical records were reviewed. An immunohistochemical study was performed on formalin-fixed paraffin-embedded tissue of 18 primary tumours and five recurrences with antibodies for neuronal (neuron specific enolase, synaptophysin, neurofilament, chromogranin A), epithelial [epithelial membrane antigen (EMA), cytokeratin], glial [glial fibrillary acidic protein (GFAP)], muscle (desmin, h-caldesmon, alpha-smooth muscle actin, myogenin) differentiation and with two anti-CD99 antibodies. All tumours showed at least one neuronal marker except chromogranin A; a variable number of cells were GFAP+ or EMA+ in 18/23 tumours. Six primary tumours and one recurrence were positive for cytokeratin and/or one muscle antigen except myogenin. CD99 was observed in 33% of the cases. The mean duration of overall survival was 20 months. The estimated overall survival rates were 61% at 1 year, 29% at 2 years, and 18% at 3 years. Two factors of poor prognosis were identified by univariate analysis: a positive cerebrospinal fluid cytology at diagnosis and the absence of complete resection. No distinct immunophenotype was statistically related to survival. CONCLUSIONS: A multidirectional differentiation is a frequent event in supratentorial PNETs but has no apparent influence on the outcome of this aggressive neoplasm.

12E7 Antigen↗

PubMed2004

Mutations within the MGC4607 gene cause cerebral cavernous malformations.

Cerebral cavernous malformations (CCM) are hamartomatous vascular malformations characterized by abnormally enlarged capillary cavities without intervening brain parenchyma. They cause seizures and focal neurological deficits due to cerebral hemorrhages. CCM loci have already been assigned to chromosomes 7q (CCM1), 7p (CCM2), and 3q (CCM3) and have been identified in 40%, 20%, and 40%, respectively, of families with CCM. Loss-of-function mutations have been identified in CCM1/KRIT1, the sole CCM gene identified to date. We report here the identification of MGC4607 as the CCM2 gene. We first reduced the size of the CCM2 interval from 22 cM to 7.5 cM by genetic linkage analysis. We then hypothesized that large deletions might be involved in the disorder, as already reported in other hamartomatous conditions, such as tuberous sclerosis or neurofibromatosis. We performed a high-density microsatellite genotyping of this 7.5-cM interval to search for putative null alleles in 30 unrelated families, and we identified, in 2 unrelated families, null alleles that were the result of deletions within a 350-kb interval flanked by markers D7S478 and D7S621. Additional microsatellite and single-nucleotide polymorphism genotyping showed that these two distinct deletions overlapped and that both of the two deleted the first exon of MGC4607, a known gene of unknown function. In both families, one of the two MGC4607 transcripts was not detected. We then identified eight additional point mutations within MGC4607 in eight of the remaining families. One of them led to the alteration of the initiation codon and five of them to a premature termination codon, including one nonsense, one frameshift, and three splice-site mutations. All these mutations cosegregated with the disease in the families and were not observed in 192 control chromosomes. MGC4607 is so far unrelated to any known gene family. Its implication in CCMs strongly suggests that it is a new player in vascular morphogenesis.

Female↗

PubMed2004

Ex vivo bone mineral density of the wrist: influence of medullar fat.

The cone beam technology was recently proposed in a third generation of densitometers (dual photon X-ray absorptiometry, DXA such as the Lexxos densitometer). Because fat is a well-known problem with DXA, we have designed a cadaver study to compare the influence of medullary lipids on the measures performed with the Hologic QDR4500 and the Lexxos. Twenty-three human distal radii were obtained and analyzed in parallel on both densitometers; bone mineral density (BMD) was measured at the distal radius with standard softwares and on a standardized square regions of interest (ROI). Bones were then defatted and a new series of measurement was performed. Bones were then thoroughly dried and a cube was prepared at the distal radius with a banding saw. Trabecular and total bone volumes were measured by microcomputerized tomography. Ash eight was obtained after calcination of the blocks. BMD could be measured on the Lexxos before and after delipidation but this was not possible with the QDR4500. The X-ray image quality was better with the Lexxos. Delipidation had a very significant effect on measurements: after defatting, BMD values were considerably reduced (-49.8 +/- 19.4%). BMD before/after defatting were significantly correlated (r = 0.81, P < 0.0001) but bone mass appeared to reflect 66% of the variance. BMD was significantly correlated with BV/TV after defatting (r = 0.44, P < 0.03) but the correlation improved when cortices were taken into account (r = 0.70, P < 0.0001). Ash weight was significantly correlated with BMD and total bone volume (respectively, r = 0.84, P < 0.0001; r = 0.53, P < 0.03), but not with BV/TV. BMD at the distal radius is influenced by marrow fat and cortical density.

Bone Density↗

PubMed2004

Persistent carotid-vertebrobasilar anastomoses: how and why differentiating them?

The persistent carotid-vertebrobasilar anastomoses (PCVBA) can be explained by an interruption of the vertebrobasilar system (VBS) embryogenesis. We present two very rare cases of persistent anastomoses: a hypoglossal artery and a type I proatlantal artery, insisting on the angiographic criteria allowing differentiation. After a brief review of the embryogenesis of the VBS, we describe the different types of persistent anastomoses (hypoglossal, type I and II proatlantal, trigeminal and otic arteries). We will insist on the potential risks, not well-known, but typical of each anastomosis. PCVBA usually are incidental findings but imaging follow-up may be required since aneurysms may develop.

Aneurysm, Ruptured↗

PubMed2004

Preferential retroviral-mediated transduction of EBV- and CMV-specific T cells after polyclonal T-cell activation.

Graft-versus-host disease, resulting from the T cells present in allogeneic hematopoietic stem cell (HSC) inoculums, can potentially be treated if a suicide gene has been introduced into the donor T cells. However, the diversity and functionality of the transfused T-cell population, including EBV- (EBV-T) and CMV-specific (CMV-T) CD8+ T cells, which are particularly important for immunosuppressed individuals undergoing HSC transplants, are often modified by the gene transfer protocol. Here, we show that following polyclonal T-cell activation, EBV-T and CMV-T cells are preferentially transduced by oncoretroviral vectors, as compared to the bulk CD8+ T-cell population. This preferential transduction is associated with higher surface levels of PiT-2, the receptor for the amphotropic envelope with which the virions are pseudotyped. Moreover, EBV-T and CMV-T cells proliferate more extensively as compared to bulk CD8+ T cells. Thus, retroviral-mediated transduction can be biased toward a given antigenic specificity, even under conditions of polyclonal stimulation.

CD8-Positive T-Lymphocytes↗

PubMed2004

Treatment of Neotrombicula autumnalis dermatitis in dogs using two topical permethrin-pyriproxyfen combinations.

Few data are available in the literature on the dermatological consequences and treatment of Neotrombicula autumnalis infestation in dogs and cats. In this study, 15 dogs naturally infested with Neotrombicula were affected with moderate to severe pruritic dermatitis. The dermatitis resolved with successful treatment of the parasitic infestation. In 14 dogs, treatment using a topical permethrin-pyriproxyfen combination (pump-spray or 'line-on') was effective within one to three weeks. Two applications were necessary in four dogs. Careful follow-up was conducted in all cases. Statistical analysis was performed to assess the impact of treatment on the parasite population and clinical signs over the three-week study period.

Administration, Cutaneous↗

PubMed2003

Radio-anatomic study of the pancreatic duct by MR cholangiopancreatography.

To compare the performance of MR-cholangiopancreatography (MRCP) and that of classical anatomy in the depiction of the main pancreatic duct, 50 MRCP examinations were done in patients free of pancreatic disease. Axial and coronal sections 20 mm thick were obtained in a Single Shot Fast Spin Echo (SSFSE) sequence. The following were analyzed: (1) visibility of pancreatic duct structures, (2) form of the main pancreatic duct, (3) various angulations of the duct and (4) diameter of the duct. Anatomic variants were noted. These findings were compared with anatomic and radio-anatomic (ERCP) data in the literature. The main pancreatic duct was visualized in 100% of cases and the accessory pancreatic duct in 61%. The form, diameter and angulations of the various segments of the pancreatic duct were similar to those reported in the literature. These findings are reported in the axial and coronal planes. Comparison with major anatomic classifications was not possible. MRCP enables in vivo anatomic exploration of the main pancreatic duct. Horizontal sections provided new radio-anatomic information. The technique nevertheless remains limited by poor spatial resolution.

Adult↗

PubMed2003

A specific PCR for the detection of Mycoplasma putrefaciens, one of the agents of the contagious agalactia syndrome of goats.

Mycoplasma putrefaciens is listed as one of the etiologic agents of the contagious agalactia syndrome by the world organisation for animal health. This species has been characterized only recently, 1974, and the number of outbreaks caused by this microorganism so far is very scarce. It induces mastitis in infected goats although other symptoms such as arthritis in adults and septicaemia in kids are also frequently described. Up to now, the identification of M. putrefaciens relied on classical isolation and identification techniques which present a number of limitations. Specific primers for PCR have been designed based on sequence comparisons of the ArcB gene among the 'Mycoplasma mycoides cluster' and related species such as Mycoplasma cottewii and Mycoplasma yeatsii. Sequence alignments confirmed the taxonomic position of M. putrefaciens, which is related to the 'M. mycoides cluster' but also very close to M. yeatsii. The polymorphism observed amongst the different ArcB sequences allowed the determination of a primer pair yielding a specific amplification of a 316 bp-long DNA fragment by PCR. This PCR was validated in two different laboratories with a variety of mycoplasma strains isolated from goats. This new PCR technique will be very useful for a quicker determination of M. putrefaciens strains as well as a better understanding of the prevalence of M. putrefaciens infections.

Animals↗

PubMed2002

Preventing transmission of sarcoptic mange from sows to their offspring by injection of ivermectin. Effects on swine production.

A blind and controlled field study was conducted on a pig farm in Australia to evaluate the activity of 1% ivermectin solution when injected into pregnant sows that were naturally infested with mites. The study was designed to appreciate the tolerance of the product on sows (litter size, litter birth weights, litter weaning weights, pre-weaning mortality) and to show the effects of sarcoptic mange on the growth performances of their offspring. Twenty sows were selected and ranked on Day-10, prior to the start of the study, on the basis of positive mite counts and parity. Sows were randomly allocated into two groups, A and B. On Day-7, they were injected once with product A (1 ml/33 kg; yielding 300 microg ivermectin/kg BW) or product B (placebo), respectively and then moved to the farrowing unit. Mite counts, ear and body lesions were scored and recorded. The average daily weight gain (ADG) was calculated on piglets from birth to Day-45 (ADG(45)) and birth to Day-70 (ADG(70)). Ivermectin was 100% efficient in preventing the transmission of scabies mites and did not have negative effect on the pregnant sows. Growth performances (ADG(45) and ADG(70)) of piglets from treated sows were significantly higher (452 and 541.5 g per day) than that from untreated sows (433.5 and 518.4 g per day) respectively, confirming that sarcoptic mange is detrimental to the production performances of growing pigs.

Animals↗

PubMed2001

Neuronal promoter of human aromatic L-amino acid decarboxylase gene directs transgene expression to the adult floor plate and aminergic nuclei induced by the isthmus.

In order to analyze the regulatory sequences involved in the neuronal expression of aromatic L-amino acid decarboxylase (AADC), we have generated transgenic mice carrying the LacZ gene under the control of a 3.6-kb human aadc genomic fragment flanking the neuronal alternative first exon. A series of double labeling experiments were performed to compare the pattern of transgene expression to that of specific markers for catecholaminergic and serotonergic neurons. In the adult brain parenchyma, transgene expression was observed in the substantia nigra (SN), the ventral tegmental area (VTA) and the dorsal, medial and pontine raphe nuclei. A large degree of co-expression was observed with tyrosine-hydroxylase (TH) in the SN and VTA, and with serotonin (5-HT) in the dorsal raphe nucleus. Moreover, expression was observed in cells that were both TH- and 5-HT-negative, in particular in the ventral tegmental decussation and the dorsal tip of the VTA. Transgene expression was also observed in the walls of central cavities. Cells positive for both beta-gal and PSA-NCAM were localized in the ventral ependyma of the third and fourth ventricle, and of the central canal of the spinal cord, in what appears to be the adult floor plate. Transgene expressing, PSA-NCAM negative, cells located along the ventral midline of the spinal cord seemed to have migrated out of the ependyma. Our data thus reveal the complexity of aadc gene regulation. The present transgene provides a unique marker for monoaminergic nuclei induced by the isthmus and for the adult floor plate.

Animals↗

PubMed2001

Effects of treatments with endectocide on the weight gain of grazing cattle in a warm temperate climate.

Five groups of 20 weaned beef calves were injected subcutaneously with either an ivermectin, a doramectin, an abamectin long-acting formulation, an ivermectin long-acting formulation or a saline control, at turnout and 60 and 120 days later. The animals grazed the same pasture and were sampled and weighed at turnout and 30, 60, 90, 120, 150 and 180 days later. At turnout the mean bodyweights of all the groups were similar and faecal culture showed that they had a mixed strongyle infection of Cooperia, Haemonchus, Ostertagia, Oesophagostomum and Trichostrongylus species. After 180 days, the mean bodyweight gains of each group were respectively 62.1 kg, 102.2 kg, 106.4 kg, 107.3 kg and 110.1 kg for the control, ivermectin, doramectin, ivermectin long-acting and abamectin long-acting groups. All the products significantly improved the weight gains of the cattle, and significantly reduced their faecal egg counts.

Animals↗

PubMed2001

Regulated control by granulocyte-macrophage colony-stimulating factor AU-rich element during mouse embryogenesis.

In vitro studies have indicated that the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression is regulated at the posttranscriptional level by the AU-rich element (ARE) sequence present in its 3' untranslated region (UTR). This study investigated the importance of the ARE in the control of GM-CSF gene expression in vivo. For this purpose, transgenic mice bearing GM-CSF gene constructs containing or lacking the ARE (GM-CSF AU(+) or GM-CSF AU(-), respectively) were generated. Both transgenes were under the transcriptional control of the immediate early promoter of the cytomegalovirus (CMV) to ensure their early, widespread, and constitutive expression. The regulation imposed by the ARE was revealed by comparing transgene expression at day 14 of embryonic development (E14); only the ARE-deleted but not the ARE-containing construct was expressed. Although GM-CSF AU(+) embryos were phenotypically normal, overexpression of GM-CSF in E14 GM-CSF AU(-) embryos led to severe hematopoietic alterations such as abnormal proliferation of granulocytes and macrophages accompanied by an increased number of peroxidase-expressing cells, their putative progenitor cells. These abnormalities compromise development because no viable GM-CSF AU(-) transgenic pups could be obtained. Surprisingly, by E18, significant accumulation of transgene messenger RNA was also observed in GM-CSF AU(+) embryos leading to similar phenotypic abnormalities. Altogether, these observations reveal that GM-CSF ARE is a developmentally controlled regulatory element and highlight the consequences of GM-CSF overexpression on myeloid cell proliferation and differentiation.

3' Untranslated Regions↗

PubMed2001

Structure, dynamics, and thermodynamics of the structural domain of troponin C in complex with the regulatory peptide 1-40 of troponin I.

The structure of the calcium-saturated C-domain of skeletal troponin C (CTnC) in complex with a regulatory peptide comprising residues 1-40 (Rp40) of troponin I (TnI) was determined using nuclear magnetic resonance (NMR) spectroscopy. The solution structure determined by NMR is similar to the structure of the C-domain from intact TnC in complex with TnI(1)(-)(47) determined by X-ray crystallography [Vassylyev, D. G., Takeda, S., Wakatsuki, S., Maeda, K., and Maeda, Y. (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 4847-4852]. Changes in the dynamic properties of CTnC.2Ca2+ induced by Rp40 binding were investigated using backbone amide (15)N NMR relaxation measurements. Analysis of NMR relaxation data allows for extraction of motional order parameters on a per residue basis, from which the contribution of changes in picosecond to nanosecond time scale motions to the conformational entropy associated with complex formation can be estimated. The results indicate that binding of Rp40 decreases backbone flexibility in CTnC, particularly at the end of the C-terminal helix. The backbone conformational entropy change (-TDeltaS) associated with binding of Rp40 to CTnC.2Ca2+ determined from (15)N relaxation data is 9.6 +/- 0.7 kcal mol(-1) at 30 degrees C. However, estimation of thermodynamic quantities using a structural approach [Lavigne, P., Bagu, J. R., Boyko, R., Willard, L., Holmes, C. F., and Sykes, B. D. (2000) Protein Sci. 9, 252-264] reveals that the change in solvation entropy upon complex formation is dominant and overcomes the thermodynamic "cost" associated with "stiffening" of the protein backbone upon Rp40 binding. Additionally, backbone amide (15)N relaxation data measured at different concentrations of CTnC.2Ca2+.Rp40 reveal that the complex dimerizes in solution. Fitting of the apparent global rotational correlation time as a function of concentration to a monomer-dimer equilibrium yields a dimerization constant of approximately 8.3 mM.

Amino Acid Sequence↗

PubMed2001

Comparative efficacy, persistent effect, and treatment intervals of anthelmintic pastes in naturally infected horses.

Eighty horses were involved in a comparative, controlled, and randomised field study conducted in Australia and Brazil. This study was undertaken to address the duration of efficacy (by faecal egg count reduction) of four anthelmintic pastes and to measure the time required between treatments on horses naturally infected by gastrointestinal nematodes. The treatment interval was based on the egg reappearance period (ERP), defined as "the period after treatment when horses have reached a positive egg count equal or superior to 200 eggs per gram (epg) of faeces". Horses were ranked according to pre-treatment faecal egg counts and randomly allocated on Day 0 to one of the four treatment groups (n=16). Group A received a combination of ivermectin at 200 microg/kg and praziquantel at 1.5mg/kg, Group B received an ivermectin paste at 200 microg/kg, Group C received a reference product containing ivermectin at 200 microg/kg, Group D received a moxidectin paste at 400 microg/kg, and Group E received a placebo. Horses were individually faecal sampled at weekly interval from Days 0 to 70 after treatment and coprocultures were made on pooled samples at the pre-treatment time on D-7 in Brazil and D-6 in Australia. The nematode population was mainly composed of small strongyles (Cyathostominae, Gyalocephalus spp., Triodontophorus spp.). All products were efficient (>90% efficacy) until Day 42 with no statistical difference between groups. From Day 49 onwards, Group C reached the threshold, while Group B exceeded this threshold on Day 56. Groups A and D remained below 200 epg for the entire study period (70 days). The interval between two anthelmintic treatments can vary according to the threshold. The ERP was defined as the period after treatment while the output of eggs is negligible or considered as acceptable. The mean number of days calculated to recurrence of 200 epg and more was, respectively, 60 days for product A, 56 days for products B and C, and 64 days for product D. If treatments are combined with other methods of limiting exposure to infective larvae on pasture, the number of treatments required will be reduced even further.

Animals↗

PubMed2001

Influence of shared epitope-negative HLA-DRB1 alleles on genetic susceptibility to rheumatoid arthritis.

OBJECTIVE: Most patients with rheumatoid arthritis (RA) express the shared epitope (SE). It is not known whether SE-negative HLA-DRB1 alleles influence the development of RA. This study examined the influence of SE-negative HLA-DR alleles (DRB1*X) on the development of RA in 3 different French populations. METHODS: HLA-DRB1 alleles were defined by polymerase chain reaction with sequence-specific oligonucleotide hybridization or sequence-specific primers. SE-negative alleles were classified according to the electric charge of their P4 pocket. HLA-DRB1 alleles *0103, *0402, *07, *08, *11 (except *1107), *12, and *13 have a neutral or negative P4 charge and are called DRB1*XP4n. HLA-DRB1*03, *0403, *0406, *0407, *0901, *1107, *14, *15, and *16 have a positive P4 charge and are called DRB1*XP4p. RESULTS: Among the SE-negative subjects, DRB1 genotypes with 1 or 2 DRB1*XP4n alleles were significantly overrepresented in the control subjects compared with the RA patients, whereas DRB1*XP4p/XP4p genotypes were equally represented in the patients and controls. In single-dose SE-positive subjects, SE/XP4n genotypes were equally represented in the patients and controls. However, SE/XP4p genotypes were significantly overrepresented in the RA patients. CONCLUSION: The DRB1*X allele polymorphism influences susceptibility to RA. Alleles that have a neutral or negative electric charge in their P4 pocket (DRB1*XP4n), such as DRB1*0103, *0402, *07, *08, *11 (except *1107), *12, and *13, protect against RA. Alleles that have a positive electric charge in their P4 pocket (DRB1*XP4p), such as DRB1*03, *0403, *0406, *0407, *0901, *1107, *14, *15, and *16, have no influence on the predisposition to RA.

Alleles↗

PubMed2001

Anatomical bases of the posterior approach to the brachial plexus for repairing avulsed spinal nerve roots.

Avulsion of nerve roots from the cervical spinal cord has always been considered as an untreatable injury, even by surgeons with expertise in this area. However, numerous experimental studies in animals, as well as a human case report, showed that if continuity is restored between the spinal cord and nerve roots, axons from spinal motor neurons can regrow into the peripheral nerve graft with a subsequent recovery of motor function. The posterior subscapular approach, based on the evolution of the posterolateral approach for removal of the first rib, is the only way to expose the entire brachial plexus from C5 to T1 from the ventral and dorsal roots to the distal nerve trunks. The purpose of this study is to investigate the topographic anatomy of the brachial plexus, with particular emphasis on the relationships important to the posterior approach and reimplantation of the ventral rootlets within the cord, either directly or using peripheral nerve grafts. The major advantage of the procedure is the proximal exposure of the plexus, with evaluation of the lesions being excellent (intradural, foraminal and proximal trunks). Reimplantation of ventral roots into the cord is relatively easy from C5 to C7, more difficult for C8 and problematic for T1, whereas reimplantation of dorsal roots into the cord is easy from C5 to T1. The disadvantages of this approach for exposure of the plexus and nerve root avulsion repair are significant: the surgical technical steps are difficult mainly because of the cervical paraspinal muscle mass, which cannot be easily "elevated and retracted" despite previous descriptions; bleeding from the venous plexus can be excessive as suggested by dissection and our own experience; the stability of the cervical spine may be compromised following extensive laminectomy with total unilateral facetectomy; exposure of the plexus distal to the division of the trunks is difficult; there may be injury to the long thoracic nerve and subsequent winging of the scapula; and pneumothorax. This approach is therefore only applicable in highly selected cases involving multiple avulsed roots with proximal lesions extending as far as the division of the trunks.

Aged↗