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At least 433 records · Page 24Linked to original sources
PubMed1974

Formation and biologic role of polyoma virus-antibody complexes. A critical role for complement.

Interaction of polyoma virus, specific antibody, and complement has been studied. Firm evidence has been gathered that C1 through C3 and not C5 through C9 enhance neutralization of virus-antiviral antibody (V-Ab) complexes. C enhancement of neutralization occurs primarily by agglutination of V-Ab complexes and not by virion lysis or attachment of large protein molecules to the V-Ab complex. In this model, binding of C1, 4, 2, 3 to the V-Ab complex may explain why some viruses concentrate in or infect certain cells bearing C3 receptors such as B lymphocytes, macrophages, and monocytes.

Animals↗
PubMed1999

The Rho GTPase Rho3 has a direct role in exocytosis that is distinct from its role in actin polarity.

Budding yeast grow asymmetrically by the polarized delivery of proteins and lipids to specific sites on the plasma membrane. This requires the coordinated polarization of the actin cytoskeleton and the secretory apparatus. We identified Rho3 on the basis of its genetic interactions with several late-acting secretory genes. Mutational analysis of the Rho3 effector domain reveals three distinct functions in cell polarity: regulation of actin polarity, transport of exocytic vesicles from the mother cell to the bud, and docking and fusion of vesicles with the plasma membrane. We provide evidence that the vesicle delivery function of Rho3 is mediated by the unconventional myosin Myo2 and that the docking and fusion function is mediated by the exocyst component Exo70. These data suggest that Rho3 acts as a key regulator of cell polarity and exocytosis, coordinating several distinct events for delivery of proteins to specific sites on the cell surface.

Actins↗
PubMed2004

Causes of death among human immunodeficiency virus (HIV)-infected adults in the era of potent antiretroviral therapy: emerging role of hepatitis and cancers, persistent role of AIDS.

BACKGROUND: In the era of highly active antiretroviral therapy (HAART) mortality has decreased substantially among human immunodeficiency virus (HIV)-infected people with access to HAART, but there are concerns regarding co-morbidities and adverse effects of HAART, which may impair vital prognosis. The Mortality 2000 study examined the causes of death in HIV-infected adults at a national level in France in the year 2000. METHODS: All French hospital wards known to be involved in the management of HIV infection were asked to notify prospectively the deaths that occurred in 2000 among HIV-infected adults. The causes of death were documented using a standardized questionnaire. RESULTS: The 185 participating wards notified 964 deaths. The main underlying causes of death were AIDS-related (47%, non-Hodgkin's lymphoma: 23%), viral hepatitis (11%, hepatitis C: 9%, hepatitis B: 2%), cancer not related to AIDS or hepatitis (11%), cardiovascular disease (7%), bacterial infections (6%), suicide (4%), and adverse effect of antiretroviral treatments (1%). Among AIDS-related deaths, HIV infection had been diagnosed recently in 20%. Smoking was recorded in 72% of cancer-related deaths and alcohol consumption in 54% of hepatitis-related deaths. Among non-HIV related deaths between 25 and 64 years, the proportion of infectious diseases (including HCV and HBV-related deaths) was higher in HIV-infected adults than in the general population. CONCLUSIONS: Improved strategies for detecting HIV infection before AIDS-defining complications occur are needed in the era of HAART. The prevention of non-AIDS related cancers, especially lung cancer, the management of non-Hodgkin's lymphoma, and of viral hepatitis are also important priorities.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Cephalic reflexes: their role in digestion and possible roles in absorption and metabolism.

Stimulation of the oral cavity immediately elicits salivation, gastric acid secretion and pancreatic exocrine and endocrine secretions that serve to prepare the alimentary canal for digestion, transport and utilization of ingested nutrients. Oropharyngeal-stimulated responses are reliably initiated by the taste and smell of food. These gastrointestinal reflexes, often referred to as anticipatory or cephalic phase responses, are mediated by the autonomic nervous system and are believed to be independent of the postabsorptive effects of ingested nutrients. A common pathway used by cephalic phase responses to trigger gastrointestinal secretions is the vagus. Several studies have also demonstrated that cephalic stimulation activates both the sympathetic and parasympathetic nervous systems and thus, many cephalic-metabolic reflexes may arise indirectly from more general physiological changes that accompany oropharyngeal stimulation. The present studies suggest that oral stimulation results in alterations in intestinal function. Specifically, oropharyngeal stimulation of conscious, unrestrained rats with sucrose increases the uptake of radioactive glucose from the small intestine into the hepatic portal blood.

Animals↗
PubMed1993

Biosynthesis and metabolism of retinoic acid: roles of CRBP and CRABP in retinoic acid: roles of CRBP and CRABP in retinoic acid homeostasis.

The enzymes that constitute the pathway of retinoic acid biosynthesis and metabolism may recognize retinoid binding proteins as effectors and substrates. Apocellular retinol-binding protein (CRBP) stimulates a bile-salt independent membrane-bound retinyl ester hydrolase resulting in the hydrolysis of endogenous retinyl esters and the formation of holoCRBP. HoloCRBP delivers retinol to a microsomal nicotin-amide-adenine dinucleotide phosphate-dependent dehydrogenase, protects it from artifactual oxidation and denies enzymes that cannot recognize the binding protein access to retinol. The retinal synthesized may be transferred from the microsomes to the cytosol by CRBP. A cytosolic retinal dehydrogenase has been purified that produces retinoic acid from retinal generated by microsomes in the presence of CRBP and from the complex CRBP-retinal itself. Thus, CRBP(type I) seems to channel retinoids through the reactions of retinoic acid synthesis via a series of protein-protein interactions. Cellular retinoic acid-binding protein (type I) facilitates retinoic acid metabolism by sequestering it and by acting as a low Km substrate, thereby also modulating the steady-state concentrations of retinoic acid.

Animals↗
PubMed1976

Studies on the biological role of DNA methylation. II. Role of phiX174 DNA methylation in the process of viral progeny DNA synthesis.

In vivo inhibition of bacteriophage phiX174 DNA methylation by nicotinamide resulted in the accumulation of replicative intermediates with multiple-genome length single-stranded "tails". These abnormal replicative intermediates could not be chased into viral single-stranded circular DNA. The effect of nicotinamide on phage maturation and accumulation of abnormal replicative intermediates could be reversed by washing out the inhibitor. The results suggest that the single methyl group present in the viral DNA serves as a recognition site for a specific endonuclease, probably the gene A protein product, that is responsible for the excision of the single-stranded one-genome long viral DNA, before final maturation of the virus occurs.

Coliphages↗
PubMed1977

Studies on the biological role of DNA methylation: III Role in excision of one-genome long single-stranded phi X 174 DNA.

Accumulation of replicative intermediates of the bacteriophage phi X174 was observed in E. coli C infected cells when phage DNA methylation has been inhibited by nicotinamide or when cells were infected with a temperature-sensitive mutant in gene A. Analysis of the accumulating replicative intermediates by electron microscopy revealed that these molecules are composed of double-stranded DNA rings with multiple-genome length single-stranded "tails". These results suggest that the single 5-methylcytosine residue present in the phage DNA serves as a recognition site for the gene A protein mediating the excision of one-genome long phage DNA. This excision process is oligatory for the final maturation of the phage.

Coliphages↗
PubMed2003

Deletion of all Cochliobolus heterostrophus monofunctional catalase-encoding genes reveals a role for one in sensitivity to oxidative stress but none with a role in virulence.

The genome of the maize pathogen Cochliobolus heterostrophus encodes three unlinked monofunctional catalase-encoding (CAT) genes that singly or in combination could offer protection against the harmful effects of oxidative stress. Phylogenetic analysis placed the CAT2 and CAT3 proteins in a cluster with large subunit catalases (CAT3 has a secretory signal sequence and was grouped with known secreted catalases), whereas CAT1 clustered with small subunit catalases. Single, double, and triple cat mutants were created and screened for sensitivity to hydrogen peroxide and altered virulence on maize. All mutants deficient in CAT3 had enhanced sensitivity to hydrogen peroxide, as compared with wild type or with mutants deficient in CAT1, CAT2, or both. All catalase-deficient mutants had normal virulence to maize. Thus, the secreted CAT3 protein protects the fungus from oxidative stress during vegetative growth, but members of this enzyme family, alone or in combination, are not essential for virulence.

Ascomycota↗