Biomedical subjects
Publications and source records attributed to G Acs.
Reovirus cores catalyze a ribonucleoside triphosphate (rNTP)-dependent pyrophosphate exchange reaction in the presence of all four rNTP species. When rNTP species are tested individually, only guanosine-5'-triphosphate supports pyrophosphate exchange.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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The cellular RNA content of mouse fibroblasts incubated with actinomycin decreases at a rate of about 1 to 1.5 per cent per hour, while DNA and protein content remain unchanged. This degradation affects nuclear and cytoplasmic RNA, ribosomal and soluble RNA. The breakdown products appear quantitatively in the acid-soluble fraction of the cells and the medium. Polynucleotides synthesized a short period (120 minutes) prior to exposure to actinomycin are degraded before those synthesized 8 to 12 hours previously.
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Cultured 3T3 mouse fibroblasts transfected with cloned hepatitis B virus genome and DNA coding for methotrexate-resistant dihydrofolate reductase, produce and secrete significant amounts of hepatitis B surface antigen (HBsAg). Ultrastructural morphometry revealed that fibroblasts transfected with hepatitis B virus DNA contained significantly more lysosomes than did fibroblasts transfected with the gene coding for methotrexate resistance or normal fibroblasts. Although abundant HBsAg was found in the cytoplasm of transfected fibroblasts by immunologic methods, HBsAg particles were not detected by electron microscopy. Immunoelectron microscopy localized HBsAg to the nuclear envelope, rough endoplasmic reticulum, and endoplasmic cisternae. These findings suggest that the transfected cells produce mainly nonparticulate HBsAg or that they have a defect in intracisternal packaging of HBsAg into particles.
The region of the hepatitis B virus (HBV) genome coding for the viral envelope proteins contains three inphase ATGs that are conserved among viral subtypes. Each of these ATGs can be used as mRNA initiation codons. The three translated proteins share a carboxy-terminal region (the S protein) and extend amino-terminally to include the pre-S2 region in the middle (M) protein, and the pre-S1 and pre-S2 regions in the large (L) protein. We have inserted the HBV DNA coding for the M protein into a baculovirus expression vector. Infected insect cells transcribe a mRNA that is initiated solely within a baculovirus promoter, and that contains the initiator codons for both M and S proteins. Although these cells primarily secrete the M protein, the major translational product is the S protein, which is not secreted. This preferential translation, the result of the use of an internal initiator codon, demonstrates that the regulation of HBV envelope protein production can occur at the translational level.
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The increasing incidence of HIV infection in the pediatric population is of concern for the practicing dentist. Long incubation periods of the virus, combined with difficulty in detection, results in many undiagnosed cases of prenatal and natal infections with HIV. As a result, many dentists will unknowingly treat HIV-positive children. This article presents most common features of pediatric HIV infection, placing special emphasis on manifestations which affect the head, neck, and oral tissues.