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Biomedical subjects

W E Rawls

Publications and source records attributed to W E Rawls.

At least 73 records · Page 4Linked to original sources
PubMed1981

Mechanisms of persistence in arenavirus infections: a brief review.

A characteristic of the arenaviruses is persistent infections in their natural host. Age at infection is an important factor in the establishment of persistence. Infections early in life regularly result in persistence and this appears to be related to the immaturity of the immune system. Persistently infected animals make antibodies to the viral antigens, which indicates that the animals are not tolerant with respect to B cell functions. However, cytotoxic T cells cannot be demonstrated in persistently infected animals, suggesting a defect in effector T cell functions. The mechanisms leading to this defect in cytotoxic T cells have not been resolved. Persistence of arenaviruses in cell cultures is also regularly observed but the molecular basis for survival of the virus and cell in long-term cultures has yet to be clarified.

Animals↗
PubMed1980

Size estimation of Pichinde virus RNA by gel electrophoresis under denaturing conditions.

RNA extracted from purified Pichinde virion preparations yields four major species, two of which appear to represent the viral genome while the other two appear to be cellular ribosomal 28S and 18S RNA. The molecular weights of these RNA species have been estimated by gel electrophoresis following denaturation by either methylmercury or glyoxal/dimethyl sulfoxide. The values determined by the two methods are in close agreement. The average molecular weights of L and S Pichinde viral RNA are 2.63 x 10(6) to 2.83 x 10(6) to 1.31 x 10(6), respectively.

Arenaviridae↗
PubMed1980

Reaction patterns of herpes simplex virus type 1 and type 2 proteins with sera of patients with uterine cervical carcinoma and matched controls.

Serum from 105 individuals with diagnosed uterine cervical cancer and 231 matched controls were examined for their ability to react with a large number of herpes simplex virus type 1 or type 2 (HSV-1, HSV-2) proteins. Radiolabeled HSV-1 or HSV-2 proteins were mixed with test serum and immune complexes were isolated with staphylococcal protein A. Viral proteins in the immune complexes were resolved by polyacrylamide gel electrophoresis and visualized by fluorography. When the frequency of precipitation for cancer and control serum was calculated for each HSV-1 and HSV-2 protein, the results demonstrated that four HSV-1 and 11 HSV-2 proteins were precipitated more frequently by cases than by controls (p less than or equal to 0.05). However, since these results could be influenced by the presence or absence of HSV-2 specific antibodies as well as social, economic, and sexual history, the data were grouped and analyzed according to these parameters. This enabled all significant differences between case and control sera in the precipitation of HSV-1 or HSV-2 proteins to be abolished except for two HSV-2 proteins with molecular weights of 38,000 and 118,000. These two proteins appear to be tumor associated and not merely covariables of past infection or risk factors alone.

Adult↗
PubMed1980

Factors affecting the expression of carcinoembryonic antigen at the surface of cultured human colon carcinoma cells.

Factors affecting the expression of carcinoembryonic antigen (CEA) at the surface of in vitro human colon carcinoma cells were determined using 125I-labeled antibodies. Binding of specific anti-CEA antibodies resulted in polar redistribution of CEA, followed by endocytosis of most of the CEA-anti-CEA complexes. These processes were temperature and energy dependent. CEA removed from the tumor cell surface by antibody was totally replaced within 6 hr at 37 degrees, and the reexpression of CEA required protein synthesis. Examination of clonally derived subpopulations of various strains of human colon cancer cells indicated that control over the level of cell surface CEA expressed was genetically stable in vitro. CEA expression was enhanced in a low-CEA-producing strain by incorporating theophylline in the culture medium, and the inclusions of bromodeoxyuridine enhanced the expression of a high-CEA-producing strain. The kinetics of enhancement of CEA expression by these two drugs differed. These findings suggest that CEA expression may be controlled by more than a single gene function.

Antibodies, Neoplasm↗
PubMed1979

Epidemic of mumps in a partially immune population.

The incidence of mumps in vaccinated and nonvaccinated schoolchildren was studied after a recent epidemic. Information was collected by telephone interviews with the parents and a review of the physicians' records. The vaccine appeared to be effective, for the incidence of mumps in the 145 vaccinated children--5.5%, or 8 cases--was significantly less (P less than 0.001) than the incidence in the 350 children considered susceptible to infection--21.7%, or 76 cases. The percentage of children who had been immunized decreased with increasing age, and acquisition of immunity through natural infection had the reverse trend; thus, the proportions of children susceptible to infection in each age group were about the same, and the age-specific attack rates were similar. Although the mothers were accurate in indicating absence of vaccination, they incorrectly indicated vaccination of their children 43.0% of the time; this error in reporting could influence vaccine administration in older children. Our findings suggest that mumps vaccination may substitute for natural illness in immunizing populations, and that more extensive use of the vaccine over a broader age range is required to prevent similar epidemics in the future.

Adolescent↗
PubMed1979

Pseudotypes of vesicular stomatitis virus and Pichinde virus.

Super-infection of Pichinde virus-infected cells with vesicular stomatitis virus (VSV) resulted in the production of pseudotype virus which was not neutralized by antiserum to VSV but which was neutralized by antiserum to Pichinde virus. Analysis of pseudotype virus production in relation to the kinetics of replication of Pichinde virus demonstrated that pseudotype virus production occurred when super-infection with VSV was initiated 8 h or more after infecting the cells with Pichinde virus. The quantities of pseudotype virus produced correlated with the quantities of Pichinde virus antigen detected on the surface of the cells both during acute infection and in cells chronically infected with Pichinde virus. The observations indicate that pseudotype of VSV and Pichinde virus are readily formed and that the formation of pseudotype virus may be used to examine the Pichinde virus antigens expressed on the surface of infected cells.

Antigens, Viral↗
PubMed1979

Abortive replication of vaccinia virus in activated rabbit macrophages.

During the course of infection of rabbits with vaccinia virus, macrophages obtained from the peritoneal cavity develop bactericidal activity and the replication of vaccinia virus becomes restricted in these cells. The abortive replication of vaccinia virus in the activated macrophages was characterized in the present study. The virus adsorbed to and was uncoated equally well in macrophages from both normal and infected rabbits. A burst of deoxyribonucleic acid synthesis of comparable magnitude took place 3 to 6 h after infection in both normal and activated macrophages. Although the production of viral antigens, as detected by immunodiffusion and immunofluorescence, was the same in both types of cells, very few virus particles were formed in activated as compared with normal macrophages. We conclude that a block in a late step of the virus replication cycle occurred in the activated macrophages.

Animals↗
PubMed1979

Distinctive RNA transcriptase, polyadenylic acid polymerase, and polyuridylic acid polymerase activities associated with Pichinde virus.

Three RNA polymerase activities were found and associated with purified Pichinde virus, a member of the Arenaviridae. A heat-labile polymerase activity which required all four ribonucleoside triphosphates for optimal activity co-sedimented on sucrose gradient centrifugation with the viral ribonucleoprotein complex from detergent-disrupted virus preparations. This enzyme synthesized heteropolymers which represented about 23% of the genome RNA as determined by nucleic acid hybridization. Two relatively heat-stable polymerase activities which differed in their cation requirement and substrate specificity were recovered with the virus-associated ribosomes. These polymerase activities synthesized homopolymers of limited chain length: in the presence of 10 mM Mg2%, polyuridylic acid was made, whereas in the presence of 1 mM Mn2%, polyadenylic acid was made. The addition of complementary RNA synthesized with the viral transcriptase in vitro to the reaction mixture containing the polyadenylic acid polymerase activity resulted in the terminal addition of polyadenylic acid to the complementary RNA. The possible function of the ribosome-associated polymerase activities in the replication of the virus is discussed.

Animals↗
PubMed1979

Selective assay for herpes simplex viruses expressing thymidine kinase.

A technique for selecting herpes simplex viruses expressing the viral thymidine kinase (TK+) from a population of predominantly TK- viruses was developed. This was accomplished by infecting TK- cells and incubating the cultures under a liquid overlay medium containing methotrexate. Since the TK- cells survive in this medium for only a limited period of time, it was necessary to add fresh uninfected TK- cells 48 h after infection. The technique allowed the detection and quantitation of the TK+ virus fraction in mixtures of TK+ and TK- viruses where the TK+ fraction was present in frequencies as low as 10(-5). It was also used to estimate reversion frequencies and to obtain and analyze TK+ revertants from TK- mutant strains of herpes simplex virus type 1.

Cell Line↗
PubMed1978

Elevated levels of carcinoembryonic antigen in cord plasma.

41.5% of 200 newborn infants had levels of carcinoembryonic antigen (CEA) in excess of 2.5 ng/ml in their cord plasma. There was no direct correlation with the maternal CEA level although the frequency of elevated CEA was significantly greater among infants born to mothers with CEA levels greater than 2.5 ng/ml. There was no preponderance of high CEA levels among infants with low birth weights and there was no influence of maternal smoking on a cord CEA level. There was a tendency toward an increased incidence of cancer in families with infants who had elevated CEA levels and a reverse trend was noted with respect to diabetes; however, these associations were not statistically significant. We were unable to define clearly the factors accounting for the persistent elevation of this oncofetal antigen at birth; however, the possible association with susceptibility to the development of neoplasia merits further study.

Adult↗
PubMed1978

Relationship of herpes simplex virus type-2 antibodies and squamous dysplasia to cervical carcinoma in situ.

Serum specimens from 75 women with cervical carcinoma in situ, 84 with squamous dysplasia, and 132 controls, who had previously been interviewed and tested for complement fixing antibodies against a number of organisms, were analyzed for HSV-2 antibodies. Carcinoma in situ and severe dysplasia were associated with HSV-2 antibodies. Mild dysplasia was related to evidence of prior infection by Trichomonas vaginalis, adenoviruses, and Mycoplasma pneumoniae, plus a history of vaginal discharge. Severe dysplasia was less strongly related to these variables. The relative risk of dysplasia increased with the number of different pathogens by which a woman had been infected. It is concluded that HSV-2 may be a cause of carcinoma in situ; that much dysplasia is a nonspecific reaction of the cervical epithelium to chronic inflammation; and that dysplastic lesions that are caused by HSV-2, and hence may be a precursor to carcinoma in situ, tend to be distinguished by their severity.

Adolescent↗
PubMed1978

Quantitation of antibodies to varicella-zoster virus by immune adherence hemagglutination.

Immune adherence hemagglutination was compared with the complement fixation test as a means of measuring antibodies to varicella-zoster virus. Analysis of acute- and convalescent-phase sera from patients infected with varicella-zoster or with herpes simplex virus showed the immune adherence hemagglutination test to be more sensitive than the complement fixation test, and greater cross-reactivity between the two viruses appeared to be associated with the increased sensitivity. The two assay methods were used to measure antibodies to varicella-zoster virus in 265 sera obtained from patients of different ages as well as sera from 26 patients with leukemia. There were 35 cases where antibodies were detected by immune adherence hemagglutination but not by complement fixation, whereas in five cases the converse was found. Our findings support the contention that immune adherence hemagglutination is the method of choice for detecting antibodies to varicella-zoster virus.

Acute Disease↗