Genomics and structure/function studies of Rhabdoviridae proteins involved in replication and transcription.

Some mammalian rhabdoviruses may infect humans, and also infect invertebrates, dogs, and bats, which may act as vectors transmitting viruses among different host species. The VIZIER programme, an EU-funded FP6 program, has characterized viruses that belong to the Vesiculovirus, Ephemerovirus and Lyssavirus genera of the Rhabdoviridae family to perform ground-breaking research on the identification of potential new drug targets against these RNA viruses through comprehensive structural characterization of the replicative machinery. The contribution of VIZIER programme was of several orders. First, it contributed substantially to research aimed at understanding the origin, evolution and diversity of rhabdoviruses. This diversity was then used to obtain further structural information on the proteins involved in replication. Two strategies were used to produce recombinant proteins by expression of both full length or domain constructs in either E. coli or insect cells, using the baculovirus system. In both cases, parallel cloning and expression screening at small-scale of multiple constructs based on different viruses including the addition of fusion tags, was key to the rapid generation of expression data. As a result, some progress has been made in the VIZIER programme towards dissecting the multi-functional L protein into components suitable for structural and functional studies. However, the phosphoprotein polymerase co-factor and the structural matrix protein, which play a number of roles during viral replication and drives viral assembly, have both proved much more amenable to structural biology. Applying the multi-construct/multi-virus approach central to protein production processes in VIZIER has yielded new structural information which may ultimately be exploitable in the derivation of novel ways of intervening in viral replication.

Allergic inflammation induced by a Penicillium chrysogenum conidia-associated allergen extract in a murine model.

BACKGROUND: Recent evidence has shown that viable conidia from the fungus Penicillium chrysogenum induce allergic effects in mice. The present study was conducted to determine the specific allergic dose response of C57BL/6 mice to the protease extract, Pen ch, isolated from viable P. chrysogenum conidia. METHODS: Mice were treated with primary intraperitoneal (IP) injections of 10 or 100 microg of Pen ch adsorbed to alum, followed by weekly IP injections of 0.1, 1.0, or 10.0 microg Pen ch with alum for 4 weeks, and with 10.0 microg of Pen ch by intranasal (IN) inoculations the final 2 weeks before killing. RESULTS: Intraperitoneal injections of 10 and 100 microg of Pen ch for 5 weeks followed by 2 weeks of IN instillation of 10 microg induced significant increases of total serum immunoglobulin (Ig)E and IgG(1). Bronchoalveolar lavage cell counts revealed increased numbers of eosinophils and neutrophils. Histopathological examination of lungs detected perivascular inflammation by eosinophils and neutrophils and increased mucous production. CONCLUSIONS: The data presented in this study indicate that sensitization to protease allergens released by viable P. chrysogenum conidia in vivo induce a strong allergic inflammatory response in a murine model, which could have implications for people exposed to high levels of conidia of this organism.

Sudden death in neonate with staphylococcal endocarditis.

A 27-week-old girl, 936 gm, with initial diagnosis of birth asphyxia resulting from prolapse of the umbilical cord, respiratory distress syndrome, and suspected neonatal sepsis received antibiotics for the first 7 days of life. On day 24, evidence developed of acute Staphylococcus aureus endocarditis of the anterior leaflet of the mitral valve, and she died 4 days later. We believe that a rapid enlargement of the endocardial vegetation caused acute occlusion of the small mitral valve and was the cause of sudden death in this infant.

Enzyme and size profiles in chronically inactive cat soleus muscle fibers.

Spinal isolation (SI), i.e., the isolation of the lumbar spinal cord via a rostral and a caudal cord transection and bilateral dorsal rhizotomy, was used to determine the effects of chronic (6 months) inactivity on the size and metabolic properties of fibers in the cat soleus. Fibers were classified as dark or light, based on their staining reactions to myosin ATPase, alkaline preincubation, and immunohistochemically as expressing fast and/or slow myosin heavy chains (MHC). Succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) activities were assessed histochemically. Following SI, both the light and the dark ATPase fibers in the SI cats were significantly smaller than the light ATPase fibers in the controls. Normally 100% of the fibers were light ATPase and reacted exclusively with the slow antibody. After SI, approximately 45% of the fibers were dark ATPase fibers, many reacting with both fast and slow MHC antibodies. The total amount and concentration of GPD were higher in the light and dark ATPase fibers in SI compared with light ATPase fibers in controls. In contrast, although the total amount of SDH per fiber was decreased, reflecting the decrease in fiber size, the mean SDH concentration per fiber was unchanged following SI. These data indicate that there is a close coordination in the regulation of GPD activity and the type of myosin. SDH activity, on the other hand, appears to be resistant to decreased levels of activity and unloading, i.e., there seems to be a minimum level of oxidative potential in the soleus that is independent of activity level. Fiber sizes, however, are very sensitive to less-than-normal amounts of neuromuscular activity and/or loading.

Effects of periodic weight support on medial gastrocnemius fibers of suspended rat.

Based on the current view that muscle fiber types reflect, at least to some degree, the probability of excitation of motor units in most normal movements, it was hypothesized that brief moderate periods of weight support would have little effect on a muscle that consists predominantly of high-threshold motor units. To test this hypothesis, the effects of 7 days of hindlimb suspension (HS) and HS plus intermittent weight support activity on the size and metabolic properties of individual fibers in the medial gastrocnemius (MG) were studied. HS resulted in a 40% decrease in the mean cross-sectional area of fibers that stain either dark or light for myosin adenosinetriphosphatase (ATPase) at an alkaline preincubation and are located in the deep region (i.e., close to the bone) of the MG. Dark ATPase fibers located in the superficial region were 17% smaller than controls (P greater than 0.05). Although the mean succinate and alpha-glycerophosphate dehydrogenase activities (optical density/min) per muscle fiber were not significantly (P greater than 0.05) affected by HS, it appeared that selected fibers of the deep MG region of HS rats had elevated enzyme activities. HS plus walking on a treadmill for 10 min every 6 h at 5 m/min and at a 19 degrees incline (total of 40 min/day) resulted in mean fiber cross-sectional area and enzyme activities nearer to control than the HS values. All adaptations were much less obvious in the fibers in a superficial (i.e., away from the bone) MG region.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise effects on the size and metabolic properties of soleus fibers in hindlimb-suspended rats.

The soleus atrophies rapidly when a rat is subjected to hindlimb suspension (HS), probably as a result of a decrease in the force encountered by the muscle. To test this premise, adult female rats were HS and half the rats were exercised (HS-EX) on a treadmill for 1.5 h.d-1 at 20 m.min-1 and a 30% grade. After 4 weeks, the midbelly of the soleus was prepared for histochemical analysis. Fibers were typed as dark or light staining for myosin ATPase, alkaline preincubation. Fiber size and quantitative histochemical enzyme activities of succinate dehydrogenase (SDH) were determined using a computer enhanced image processing system. In comparison to age-matched controls, the soleus wet weight was 69 and 30% smaller in HS and HS-EX rats. The mean cross sectional area of the dark ATPase fibers was reduced by 46 and 18% and light ATPase fibers by 69 and 48% in the HS and HS-EX, respectively. The percent dark ATPase fibers increased from 10% in the control rats to 19 and 17% in the HS and HS-EX. In both suspended groups, SDH activities in light ATPase fibers were 40% higher than control. The SDH activity of the dark ATPase fibers of HS-EX was 20% higher than control, while the dark ATPase fibers of HS were similar to control. To determine the degree to which these increases in SDH could be related to reductions in fiber size rather than increases in the actual amount of protein, integrated activity (activity/min x area) was calculated per fiber.(ABSTRACT TRUNCATED AT 250 WORDS)