Newer electrodiagnostic techniques in peripheral nerve injuries

Careful attention to technique is essential for the accurate evaluation of peripheral nerve function using conventional EMG and nerve conduction studies. Numerous technical, anatomic, and physiologic pitfalls must be avoided. The amplitudes of the M wave and SNAP contain useful diagnostic information and should be evaluated carefully in addition to conduction velocity and distal latency. Newer techniques using the F wave, H reflex, SEP, dermatomal SEP, and quantitative EMG may be helpful in evaluation of selected peripheral nerve problems. Comparative nerve conduction studies using "inching" technique permit evaluation of short nerve segments. Comparisons with parallel nerves improve diagnostic sensitivity.     

Laboratory diagnosis of variant Creutzfeldt-Jakob disease

The neuropathological and biochemical features of 33 cases of variant Creutzfeldt-Jakob disease (vCJD) diagnosed up to the end of 1998 are analysed in relation to the 646 cases of suspected CJD referred to the CJD Surveillance Unit laboratory from 1990 to 1998. Morphological studies of the central nervous system, lymphoid tissues and other organs were accompanied by immunocytochemistry; Western blot analysis of PrPRES was performed on frozen brain tissue. The findings were analysed in relation to clinical and genetic data. The pathology of vCJD showed morphological and immunocytochemical characteristics distinct from other cases of CJD. PrP accumulation was widespread in lymphoid tissues in vCJD, but was not identified in other non-neural tissues. PrPRES accumulation in vCJD brain tissue showed a uniform glycotype pattern distinct from sporadic CJD. All analysed cases of vCJD were methionine homozygotes at codon 129 of the PrP gene. No evidence currently exists to suggest that cases of CJD diagnosed in individuals who are MV or VV at codon 129 of the PrP gene represent 'human bovine spongiform encaphalopathy (BSE)'. Continued surveillance is required to further investigate this possibility, with the need to investigate autopsy tissues from suspected cases by histological and biochemical techniques.     

Platelet activating factor as a proinflammatory mediator in acetic-induced colitis in the rat

The nature of histamine receptors in peripheral tissues is still controversial. However, evidence of heterogeneous classes of binding sites for [³H]-mepyramine are reported in the literature. The aim of our study was, therefore, to investigate the nature of this heterogeneity by comparing [³H]-mepyramine study was, therefore, to investigate the nature of this heterogeneity by comparing [³H]-mepyramine binding in a central tissue (cerebellum) and in a peripheral tissue (lung) obtained from guinea pigs and to assess its dependence upon the temperature of incubation. The results revealed that the [³H]-mepyramine interaction in both tissues is temperature-dependent. At 25°C, the interaction between [³H]-mepyramine and the receptors was biphasic in the lung while only a single class of binding site was found in the cerebellum. At 0°C, [³H]-mepyramine interacted with three binding sites in the lung and two in the cerebellum. The behaviour of the reference compounds (clemastine, promethazine and histamine) also supported this temperature-dependence. Moreover, two new compounds (DF 11062 and DF 11113), synthesized in our laboratories and endowed with antihistamine activity, can differentiate between the low affinity site seen at 25°C in the lung and that seen in the cerebellum at 0°C.     

Babesia bovis : identification of immunodominant merozoite surface proteins in soluble culture-derived exoantigen

Babesia bovis merozoite proteins presenting as exoantigens in in vitro culture supernatants have been characterized. Bovine antisera to B. bovis exoantigens were used to immunoprecipitate [³⁵S]-methionine metabolically labeled or lactoperoxidase-catalyzed radioiodinated B. bovis merozoite proteins. A total of 24 metabolically labeled proteins ranging in molecular weight from 24,000 to 225,000 Da and 9 radioiodinated proteins with molecular weights varying between 24,000 and 225,000 Da were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Monoclonal antibodies to B. bovis merozoite surface proteins were also used to immunoprecipitate metabolically labeled exoantigens directly from in vitro culture supernatants. These results demonstrate epitopes from at least nine merozoite surface proteins present in the exoantigen fraction, among which are the recently characterized major surface antigens 1 and 2, rhoptry-associated protein 1, and spherical body protein 2. Received: 1 April 1997 / Accepted: 6 May 1997     

Light and Electron Microscopic Changes in the Myocardium of Influenza-Infected Turkeys

Virus isolation and titration, electrocardiography, enzyme assays and light and electron microscopic studies were undertaken in male turkeys infected with influenza A/turkey/Ontario/7732/66 virus to determine its potential role in the genesis of heart disease. Virus was isolated from the heart initially before a demonstrable viremia and terminally in declining serum viral titer. Virus was isolated from the heart muscle as early as 1 day postinoculation. Highest viral titers were found in the heart at 6 days postinoculation and coincided with maximum elevations of serum glutamic-oxalacetic transaminase and lactic acid dehydrogenase, microscopic lesions in the heart and cardiac arrhythmias. Microscopic lesions in the heart were first detected at 4 days postinoculation and consisted of disseminated areas of necrosis, focal myocarditis, pericarditis and endocarditis. Alterations in myocardial ultrastructure which followed viral infection included fragmentation and dissolution of myofibrils, dilation of the sarcotubular system, increase in membrane vesicle formation in the region of the endoplasmic reticulum, discontinuity of the sarcolemma, proliferation of mitochondrial population, swelling of mitochondria with separation and disruption of the cristae, and the presence of intramitochondrial and perinuclear densities.     

Epitope-specific humoral immunity to Plasmodium vivax Duffy binding protein

Erythrocyte invasion by Plasmodium vivax is completely dependent on binding to the Duffy blood group antigen by the parasite Duffy binding protein (DBP). The receptor-binding domain of this protein lies within a cysteine-rich region referred to as region II (DBPII). To examine whether antibody responses to DBP correlate with age-acquired immunity to P. vivax, antibodies to recombinant DBP (rDBP) were measured in 551 individuals residing in a village endemic for P. vivax in Papua New Guinea, and linear epitopes mapped in the critical binding region of DBPII. Antibody levels to rDBP(II) increased with age. Four dominant linear epitopes were identified, and the number of linear epitopes recognized by semi-immune individuals increased with age, suggesting greater recognition with repeated infection. Some individuals had antibodies to rDBP(II) but not to the linear epitopes, indicating the presence of conformational epitopes. This occurred in younger individuals or subjects acutely infected for the first time with P. vivax, indicating that repeated infection is required for recognition of linear epitopes. All four dominant B-cell epitopes contained polymorphic residues, three of which showed variant-specific serologic responses in over 10% of subjects examined. In conclusion, these results demonstrate age-dependent and variant-specific antibody responses to DBPII and implicate this molecule in partial acquired immunity to P. vivax in populations in endemic areas.     

A comparison of behavioural effects and morphological features of grafts rich in cholinergic neurons placed in two sites of the denervated rat hippocampus

This study compared the morphological characteristics and the behavioural effects of intrahippocampal septal cell suspension grafts injected either just above the pyramidal cell layer of the hippocampal region CA1 or within the dorsal leaf of the dentate gyrus (DG) in rats subjected to electrolytic fimbria-fornix lesions. The behavioural tests determined home-cage and open-field activity, as well as radial-maze performance. Cresyl-violet staining, acetylcholinesterase (AChE) histochemistry, and parvalbumin, glial fibrillary acidic protein and glutamic acid decarboxylase immunocytochemistry were used for morphological assessments. The cross-sectional area of the grafts was measured between 0.8 mm and 5.3 mm posterior to Bregma and used as an index of their development. Whether injected into CA1 or DG, the grafts provided the partially denervated hippocampus with a dense AChE-positive reinnervation. Both types of grafts were devoid of reactive astrocytes (although reactive astrocytes were found close to the graft-host interface), contained almost no parvalbumin-positive neurons and showed a high density of GAD-positive terminals. One of the main differences between the two groups of grafted rats was that the suspension injected into the DG yielded grafts that, in the vicinity of the injection sites (between 2.3 mm and 4.3 mm posterior to Bregma), had a cross ectional area exceeding that of the grafts placed into CA1 by about 63–110% (average 79%), the latter being more dispersed than the former in the coronal plane. In addition, rats with grafts in the DG exhibited granule cell degeneration in the vicinity of the injection sites, whereas rats with grafts in region CA1 showed no damage near the injection sites. Concerning the behavioural data, we found that fimbria-fornix lesions induced hyperactivity in both the home cage and the open field and impaired radial-maze performance. Compared with the lesion-only rats, the grafted rats in both groups had further increased open-field and home-cage activity. While the grafts placed into region CA1 slightly, but significantly, accentuated the lesion-induced deficit in radial-maze performance, those placed into the DG had no effect. These results suggest that intrahippocampal grafts may, in some (still unspecified) conditions, produce adverse behavioural effects or no behavioural effects, despite an acceptable graft-induced cholinergic reinnervation of the hippocampus. They do not allow a clear answer to the question of whether intra-DG and intra-CA1 septal suspension grafts exhibiting almost comparable morphological features (except in their size and their dispersion in the vicinity of the injection sites) induce behavioural effects that would depend on intrahippocampal location of the grafts. They suggest, however, that the granule cell degeneration caused by the implantation procedure, in conjunction with the intragyral development of the graft, probably does not account for some of the reported adverse behavioural effects of intrahippocampal basal forebrain grafts. Finally, the finding that septal cell suspensions placed into the DG yielded larger grafts than when an equivalent number of cells was injected into CA1 might be explained by a larger lesion-induced neurotrophic activity in DG than in region CA1, although both regions had undergone a similar degree of cholinergic denervation.     

Complex karyotypic anomalies in a bizarre leiomyoma of the uterus

Cytogenetic investigation of short-term cultures from a bizarre leiomyoma of the uterus, a tumor type not hitherto karyotypically characterized, revealed two abnormal clones with multiple complex rearrangements. Three-fourths of the aberrant cells were hypodiploid with the composite karyotype 38–44, XX,?6,?7,?10,?11,+20,?22, r(1), der(2) (:2p23→cen→2q13::1q21→1qter), der(2)t(2;9)(p21;q13), t(5;?)(q35;?), t(5;?),(q35;?), + der(5)t(5;15)(q11;q15), der(8)t(8;11)(q24;q13), t(15;?)(p12;?), der(16)t(12;16)(q13;p13),+r,+mar. The remaining abnormal mitoses were hypotetraploid, with chromosome numbers ranging from 74 to 86. These massively rearranged cells showed the same markers that were found in the hypodiploid clone, but in duplicate, indicating that this clone had arisen through polyploidization of hypodiploid cells. Flow cytometry revealed a DNA index of 1.03.     

Lung vascular smooth muscle as a determinant of pulmonary hypertension at high altitude.

The pulmonary hypertensive response to chronic hypoxia varies markedly among mammalian species. An explanation for this variability was sought by exposing seven species to hypobaric hypoxia (PB equal to 435 mmHg) for 19-48 days. Control animals were studied at 1,600 m (PB equal to 630 mmHg). The pulmonary hypertension that developed varied in the following order of decreasing severity: calf and pig (severe); rat and rabbit (moderate); sheep, guinea pig, and dog (mild). Right ventricular hypertrophy developed in proportion to the elevation in right ventricular systolic pressure. These interspecies variations in response were not correlated with the degree of arterial hypoxemia, degree of polycythemia, elevation in heart rate, or postnatal age. However, the medial thickness of the small pulmonary arteries in control animals was highly correlated with the development of pulmonary hypertension and right ventricular hypertrophy in hypoxic animals. Thus, the amount of lung vascular smooth muscle inherent within each species is a major determinant of the pulmonary hypertensive response to high altitude and contributes to the interspecies variability in this response.