Six-week-old outbred mice were infected intracerebrally with a low dose of the MS strain of herpes simplex virus type 2. About 1% of neurologically abnormal survivors developed paralysis or severe leg weakness during the first three weeks of infection. Weakness persisted with little subsequent improvement. Five to 8 months later, 4 such mice were killed, and each spinal cord was examined in Epon sections in a series of transverse sections along their lengths. All cords had 2 or more major white matter lesions which were typically greatly elongated in the rostrocaudal dimension, as seen in multiple sequential sections. While a lesion's appearance frequently suggested some degree of tract association, its size, contour and position frequently varied from level to level in a manner which is not characteristic of tract degeneration. Further, axons were preserved in these lesions, and had been remyelinated. This was accomplished by a combination of oligodendrocytes and Schwann cells. The only evidence of Wallerian degeneration in these spinal cords was a modest reduction in the cross-sectional area of a white matter column associated with the most severe lesions. These pathological findings are consistent with previous ones in this model. Rostrocaudal elongation of spinal cord lesions may be seen in other animal models of virus-induced demyelination; this and other features reported here have been described in multiple sclerosis.

Animals↗

PubMedDate not supplied

Lack of beta-amyloidosis in transgenic mice expressing low levels of familial Alzheimer's disease missense mutations.

Point mutations within the beta-amyloid precusor protein (beta-APP) gene known to segregate with Alzheimer's disease in certain families were introduced into human beta-APP cDNAs and expressed under the control of a neuron-specific enolase (NSE) promoter in mice. The transgenic animals exhibited transgene expression predominantly in neocortex and hippocampus where the levels were maximally 1.3-fold of those of wild-type mouse beta-APP. Quantitative immunoblot analysis in homozygous mice carrying different missense mutations showed slightly increased alpha-secretory processing. In V7171 mice compared to nontransgenic mice there was more alpha-secretory beta-APP (beta-APPsec) in cortex/hippocampus, less in cerebellum, and no difference in midbrain/brain stem. In none of the transgenic animals tested was a 4 kDa amyloid fragment detected by Western blotting of brain extracts, immunohistochemistry, or by 125I-A beta-binding onto brain sections. No glial reaction was observed. Behavioral analysis of mice carrying the V7171 mutation showed no appreciable deficit in comparison to wild-type mice. Together, these data suggest that low levels of expression of mutated beta-APP in 10-12-month-old transgenic mouse brains result in slightly more beta-APPsec, and are insufficient to induce amyloidogenic processing and AD-like pathology.

Alzheimer Disease↗

PubMedDate not supplied

A case-control study to investigate the association between indices of dust exposure and the development of radiologic pneumoconiosis.

A case-control study on employees at an iron ore surface mining plant was undertaken to determine which indices of occupational dust exposure related most closely to radiologic categories for pneumoconiosis. Forty cases, with radiographs compatible with the ILO Categories (1980) for simple pneumoconiosis, were matched for age, smoking habit, and date of entry into the workforce with 80 control subjects whose radiographs were read as normal. The six indices of dust exposure were cumulative and "peak" respirable dust, quartz, and iron oxide. Both iron oxide indices were not significant at the 5% level for either ILO Category 1 or Categories 2,3. The association between dust composition and ILO radiologic category for simple pneumoconiosis was consistent, with respirable quartz being the best differentiating index between the case and control groups.

Dust↗

PubMedDate not supplied

Comparison between electrochemical and optoelectrochemical impedance measurements for detection of DNA hybridization.

The principles of the electrochemical and optoelectrochemical impedance measurements on bare electrolyte/dielectric/semiconductor structures are described. The analysis of the experimental curves allows access to several indications concerning the electrical behavior of such structures. The application of these techniques to follow the electrical behavior of structures modified with two biological systems was investigated. The antibody/antigen recognition did not change the surface charge and, therefore, did not affect the impedance curves with respect to the applied potential. By contrast, the hybridization of two complementary DNA strands on the surface of the structure induced a variation of flat band potential of the semiconductor leading to a shift of impedance curves along the potential axis. This means that it is possible to detect directly the DNA hybridization without the use of labeled probes. The use of light allows the surface to be probed locally. In the future, the application of this technique for direct detection of hybridization on DNA chips should be possible.

Biosensing Techniques↗

PubMedDate not supplied

Mushroom bodies suppress locomotor activity in Drosophila melanogaster.

Locomotor activity of single, freely walking flies in small tubes is analyzed in the time domain of several hours. To assess the influence of the mushroom bodies on walking activity, three independent noninvasive methods interfering with mushroom body function are applied: chemical ablation of the mushroom body precursor cells; a mutant affecting Kenyon cell differentiation (mushroom body miniature); and the targeted expression of the catalytic subunit of tetanus toxin in subsets of Kenyon cells. All groups of flies with mushroom body defects show an elevated level of total walking activity. This increase is attributable to the slower and less complete attenuation of activity during the experiment. Walking activity in normal and mushroom body-deficient flies is clustered in active phases (bouts) and rest periods (pauses). Neither the initiation nor the internal structure, but solely the termination of bouts seems to be affected by the mushroom body defects. How this finding relates to the well-documented role of the mushroom bodies in olfactory learning and memory remains to be understood.

Animals↗

PubMedDate not supplied

Diffuse (? eosinophilic) fasciitis, atypical rash, and chronic inflammatory disease of the colon (? Crohn's disease)

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Adult↗