Peripheral neuropathy in the Twitcher mutant. A new experimental model of endoneurial edema

The Twitcher mouse (Twi/Twi) is a recently identified mutant experimental model for human globoid leukodystrophy. Affected mice develop neurologic abnormalities with demyelination of white matter and peripheral nerve due to an inherited enzyme deficiency. The neuropathy has unusual pathologic features:severe interstitial edema and infiltration by eosinophils. To investigate its pathogenesis and to identify the mechanism of demyelination, we studied vascular permeability and measured endoneurial fluid pressure. Significantly increased endoneurial fluid pressure was detected in clinically affected animals (average, 6.4 cm H2O) versus controls (1.7 cm H2O), and these data are the first measurements of EFP to be reported in mice. Increased vascular permeability to horseradish peroxidase was visualized by electron microscopy with leakage of horseradish peroxidase between endothelial cells and flooding of the endoneurial interstitium. Numerous eosinophils were present in the interstitium, as well as some polymorphonuclear cells, occasional erythrocytes, and degranulating mast cells. Abnormalities of nerve fibers included swelling of Schwann cells with intracytoplasmic inclusions, demyelination, and remyelination. As well as being a model for globoid leukodystrophy, the Twitcher is the first spontaneously occurring experimental model for endoneurial edema and increased endoneurial fluid pressure.     

Peripheral blood mononuclear cell proliferative responses to soluble and particulate heat shock protein 65 in health and inflammatory bowel disease

Objectives: The aims of this study were to determine, in peripheral blood mononuclear cells (PBMC), whether particulate antigen triggers (i) an amplified cell proliferative response compared to soluble antigen and (ii) a dysfunctional response in cells derived from patients with chronic inflammation and specifically in those with inflammatory bowel disease (IBD). Subjects: Healthy volunteers (n = 17), inflammatory controls (n = 8) and patients with IBD (n = 17) were recruited from St Thomas’ and Guys’ Hospital, London, UK. Methods: Following optimisation of experimental conditions (0.1–10.0 μg/ml antigen), PBMC were stimulated with (i) 10.0 μg/ml recombinant soluble heat shock protein 65 (hsp 65) and (ii) 1.0 and 10.0 μg/ml hsp 65 conjugated to microparticles (0.5 μm diameter). PBMC proliferative responses were measured by ³H-Thymidine incorporation at day 5 and results compared between groups using unpaired t-test. Results: Conjugation to microparticles of low dose hsp 65 significantly increased overall proliferative responses by 2–11 fold compared to soluble antigen alone (p < 0.05). However, no specific PBMC proliferative dysregulation was noted in cells from subjects with IBD. Conclusions: Low dose antigen, in microparticulate form, leads to amplified cell proliferation in primary human cells, as showed previously in cell lines and animal studies. However there is no abnormal proliferative response in cells from subjects with IBD. Received 8 February 2006; returned for revision 7 March 2006; accepted by G. Wallace 25 October 2006     

A `house doctor' scheme for primary health care for the single homeless in Edinburgh

The single homeless are a heterogeneous population with health care needs greater than those of the general population. The Edinburgh primary health care scheme for single homeless hostel dwellers is an attempt to provide an easily accessible service for this population. Having continued for eight years it is one of the longest established of such schemes. The original aim was for house doctors to take services to the residents in the hostels but the scheme has developed to include a primary health care team operating from a central clinic.

The scheme was evaluated by a study of the use of the service and by interviews with recipients of the service, hostel managers and others. The study confirmed the high health care burden from chronic handicapping conditions for this population. It was also found that the nature and level of primary health care provided by the scheme was acceptable to the hostel residents and the majority of hostel managements and to accident and emergency department staff. The female hostel dwellers expressed a need for a female practitioner in the scheme. Alternatives for primary health care provision for the single homeless are discussed in the light of the findings, and recommendations are made for the future of the scheme.

     

Efferent connections of the medial prefrontal cortex in the rabbit

The different cytoarchitectonic regions of the medial prefrontal cortex (mPFC) have recently been shown to play divergent roles in associative learning in rabbits. To determine if these subareas of the mPFC, including areas 24 (anterior cingulate cortex), 25 (infralimbic cortex), and 32 (prelimbic cortex) have differential efferent connections with other cortical and subcortical areas in the rabbit, anterograde and retrograde tracing experiments were performed using thePhaseolus vulgaris leukoagglutinin (PHA-L), and horseradish peroxidase (HRP) techniques. All three areas showed local dorsal-ventral projections into each of the other areas, and a contralateral projection to the homologous area on the other side of the brain. All three also revealed a trajectory through the striatum, resulting in heavy innervation of the caudate nucleus, the claustrum, and a lighter projection to the agranular insular cortex. The thalamic projections of areas 24 and 32 were similar, but not identical, with projections to the mediodorsal nucleus (MD) and all of the midline nuclei. However, the primary thalamic projections from area 25 were to the intralaminar and midline nuclei. All three areas also projected to the ventromedial and to a lesser extent to the ventral posterior thalamic nuclei. Projections were also observed in the lateral hypothalamus, in an area just lateral to the descending limb of the fornix. Amygdala projections from areas 32 and 24 were primarily to the lateral, basolateral and basomedial nuclei, but area 25 also projected to the central nucleus. All three areas also showed projections to the midbrain periaqueductal central gray, median raphe nucleus, ventral tegmental area, substantia nigra, locus coeruleus and pontine nuclei. However, only areas 24 and the more dorsal portions of area 32 projected to the superior colliculus. Area 25 and the ventral portions of area 32 also showed a bilateral projection to the parabrachial nuclei and dorsal and ventral medulla. The dorsal portions of area 32, and all of area 24 were, however, devoid of these projections. It is suggested that these differential projections are responsible for the diverse roles that the cytoarchitectonic subfields of the mPFC have been demonstrated to play in associative learning.     

Observations on the process of degeneration of the afferent connections to the sensori-motor cortex of the monkey.

The ultrastructural features of degeneration of the afferent connections to the sensorimotor cortex of the primate have been studied with the electron microscope. Thalamo-cortical terminals show cytoplasmic darkening and swelling of vesicles, and neurofilaments and glycogen are often prominent in the larger terminals, although true neurofilamentous hypertrophy is rare. The terminals of the commissural and association projections similarly show darkening and some swelling of vesicles but are usually smaller and neurofilaments and glycogen are rarely seen. Ethanolic-phosphotungstic acid specifically stains degenerating axons and axon terminals. Degeneration occurs more rapidly in the terminals of the association projections than in those of the longer commissural projection although terminals at different stages of degeneration are present simultaneously in both instances. Micropinocytosis of degenerating terminals has been found and both glial and neuronal profiles are involved in this. Exposed post-synaptic thickenings have been seen and these induce subsurface cisternae in the neuronal structures to which they become apposed, including axon initial segments and unmyelinated axons.Damage to a part of the central nervous system thus causes consequential changes in other regions, and these changes are relevant to the interpretation of experimental studies and to the possibility of reorganization of connections following injury.     

Inactivation of the E-cadherin gene in sporadic diffuse-type gastric cancer.

Loss of the cell adhesion molecule E-cadherin has been observed in a variety of human carcinomas, and germline E-cadherin mutations have been found in several familial cases of diffuse gastric cancer. We sought to determine the prevalence and nature of E-cadherin alterations in "sporadic" gastric carcinomas. We performed comprehensive sequencing of the coding region, loss of heterozygosity (LOH) analysis, and immunohistochemical protein expression determination on 40 sporadic gastric adenocarcinomas. In total, 7 of 25 diffuse-type cancers harbored genetic alterations in the E-cadherin gene. Novel mutations predicted to significantly compromise protein function were found within 4 of these cancers, 2 of which harbored alterations resulting in biallelic inactivation of the gene product. Three diffuse cancers failed to amplify Exon 8 of E-cadherin, suggesting the presence of a homozygous abnormality. Notably, one germline E-cadherin mutation was also identified within these "sporadic" diffuse cancers. Significant gene mutations were not found in the 14 intestinal-type or histologically mixed cancer. Immunohistochemistry revealed aberrant or negative protein expression in seven diffuse-type tumors, four of which correlated with the genetic alterations. Both diffuse and intestinal-type tumors exhibited low rates of LOH, suggesting that allelic loss at the locus is not a common mechanism for E-cadherin inactivation during gastric tumorigenesis. Our observations suggest that inactivation of the E-cadherin gene occurs only in a subset of diffuse-type gastric cancers, as the majority of cases did not contain genetic alterations or identifiable protein abnormalities. Germline E-cadherin alterations, although rare, may underlie some diffuse gastric cancer cases that have important biologic and practical implications