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Biomedical subjects

T H Weller

Publications and source records attributed to T H Weller.

At least 37 records · Page 2Linked to original sources
PubMed1986

Inoculation of guinea pigs with varicella-zoster virus via the respiratory route.

Guinea pigs were inoculated by the respiratory route with wild-type (Cyr) or vaccine (Oka) strain varicella zoster virus (VZV). Wild-type cell-free virus obtained by sonication produced neutralizing antibody responses in steroid-treated animals when given via the intratracheal route, and induced neutralizing antibody as well as a pneumonitis in normal animals when given via the intrabronchial (i.b.) route. A humoral response also followed i.b. instillation of cell-associated wild-type or vaccine strain VZV. Prior i.b. administration of thioglycollate or exposure to hyperoxia altered the number and function of pulmonary macrophages, respectively, but viral susceptibility of the guinea pigs was not enhanced. Both strains of VZV could be isolated from bronchial washings up to 48 hours after i.b. instillation of cell-associated virus, but neither strain was isolated thereafter from cultures of bronchial washings or explanted lung tissues.

Animals↗
PubMed1985

Three-year prospective study of the evolution of Manson's schistosomiasis in north-east Brazil.

A cross-sectional study of morbidity associated with Schistosoma mansoni infection in an area in North-East Brazil where the disease is endemic was carried out in 1974. The survey was repeated in 1977, before mass treatment with oxamniquine, providing a cohort of 210 individuals who had both examinations. The high prevalence of hepatomegaly (over 80%) and of splenomegaly (over 15%) contrasted with rates of 10% and 1%, respectively, in a non-endemic area. Over the 3-year period hepatomegaly spontaneously regressed in 13% of patients, and splenomegaly regressed in 56%, a phenomenon most common in older individuals with light infections. Those with heavy infections--ie, 500 or more eggs per g faeces, had an excess risk of splenomegaly of 19.6% and, of its persistence, of 61.5%. Thus, intensity of infection was a critical factor in liver and spleen involvement, and programmes of chemotherapy that reduce infection should mitigate the risk of schistosomal morbidity.

Adolescent↗
PubMed1985

Association between household triatomine density and incidence of Trypanosoma cruzi infection during a nine-year study in Castro Alves, Bahia, Brazil.

We studied the association between human incidence of Trypanosoma cruzi infection and household infestation density of Panstrongylus megistus in Castro Alves, Bahia, Brazil. During a 9-year period, 19 persons seroconverted; 17 were children, 17 lived in nonplastered houses, and 13 lived in houses infested with triatomines. Although 6 seroconverting persons lived in houses where triatomines could not be found, the risk of seroconversion was significantly greater in infested houses and 16 times greater in densely infested houses (greater than 15 bugs/person-hour of search). The highest rate of seroconversion (6/100 person-years exposure) occurred in houses containing the greatest number of bugs infected with T. cruzi (greater than 6 infected bugs/person-hour). These observations suggest that vector control measures could have a dramatic impact on transmission of T. cruzi by P. megistus.

Antibodies↗
PubMed1984

Dose-related effect of acetylsalicylic acid on replication of varicella zoster virus in vitro.

Cultivation of human embryonic lung (HEL) cells in media containing acetylsalicylic acid (ASA) at 100 micrograms/ml and maintenance at this level after inoculation with either cell-free varicella zoster virus (VZV) or virus-infected cells resulted in a 2- to 4-fold increase in yields of cell-free virus released by sonication. The degree of enhancement was dependent upon multiplicity of infection and time of harvest. Enhanced viral yields were not consistently accompanied by an increase in the number of infected cells, nor was VZV plaque formation in HEL indicator cells significantly increased in the presence of ASA at 100 micrograms/ml. In the presence of ASA at 500-1000 micrograms/ml, VZV plaque formation was inhibited; this inhibition was partially reversible, depending on concentration and period of exposure to ASA. These findings may bear on the apparent association between ASA ingestion and the development of Reye syndrome after infection with varicella virus.

Aspirin↗
PubMed1983

Varicella and herpes zoster. Changing concepts of the natural history, control, and importance of a not-so-benign virus.

New knowledge of the relationship between the varicella-zoster virus and its host suggests a heretofore unappreciated dynamic pattern. Molecular finger-printing has demonstrated a degree of heterogeneity between different strains of virus. It is probable that exogenous reinfection with different strains and endogenous reactivation are commonplace events, although usually asymptomatic. The lability of the endogenous interaction inversely parallels the responsiveness of the cell-mediated immune system--a major factor in viral containment by the human host. Thus, the therapeutic use of immunosuppressive or cytotoxic substances increases the morbidity and mortality associated with varicella-zoster. Promising new approaches to the prevention and treatment of the virus should alter the balance in favor of the host.

Acyclovir↗
PubMed1982

Miracidia infective for snails derived from eggs laid by adult Schistosoma mansoni in vitro.

Various biological mixtures commonly used as microbiological nutrients were added to a chemically defined medium, containing 0.2% (w/v) albumin, in order to assess their ability to support maturation of eggs deposited by adult Schistosoma mansoni in vitro. Of the supplements tested, only lactalbumin hydrolysate and casein hydrolysate stimulated egg deposition and subsequent egg development in vitro. Upon addition of foetal calf serum, further stimulation was noted only in casein hydrolysate-containing media. The addition of mouse red blood cells did not significantly improve the system. Some miracidia which hatched from eggs derived from casein hydrolysate-fortified cultures displayed normal behavioural characteristics, penetrated susceptible snails and established patent infections. These results provide and experimental system for exploring the nutritional requirements of developing miracidia, and the physiological determinants that influence miracidial penetrating capacity and subsequent ability to develop in a susceptible intermediate host.

Animals↗
PubMed1982

The cultivation in vitro of cells derived from adult Schistosoma mansoni. I. Methodology; criteria for evaluation of cultures; and development of media.

We describe media and a cultural system that routinely supports development in vitro plaques of several types of cells derived from adult Schistosoma mansoni. The results permit description of several types of cells observed in cultures and of criteria developed for the comparative evaluation of the supportive capacity of different media. Methods for the harvesting of worms, of their preparation for culture, and of the maintenance of cultures are detailed. The evolutionary development of the supportive media is summarized with comments on selected variables.

Amino Acids↗
PubMed1982

Deposition and maturation of eggs of Schistosoma mansoni in vitro: importance of fatty acids in serum-free media.

A serum-free medium which supports miracidial development in some eggs deposited by adult Schistosoma mansoni in vitro is described. Derivation of the medium involved examination of the supportiveness of nine chemically defined media, selection of one promoting the highest degree of worm oviposition, and supplementation of the latter with various serum fractions. The serum fraction supporting egg maturation was nondialyzable, and precipitated at 50-60% ammonium sulfate saturation. This fraction could be replaced by bovine serum albumin; however, the supportive activity disappeared if this material was delipidated. Addition of soybean lecithin, or stearic acid, to fatty-acid-free, albumin-supplemented media yielded intermediate results, while similar addition of other nonesterified fatty acids proved non stimulatory. A fatty acid mixture, rich in stearic acid, was then developed which, when added to delipidated-albumin supplemented media, supported a degree of egg development comparable to that obtained with media supplemented with 8% newborn calf serum.

Animals↗
PubMed1980

Health crusades and tropical diseases.

Worldwide attempts to eradicate yaws, malaria, and smallpox have all been effective to varying extents, and all have taught some valuable lessons that should be taken into account as a new global crusade is mounted against tropical diseases. But it should not be forgotten that infectious disease remains a major public health problem in the U.S., and new diseases are arising to replace those already vanquished.

Humans↗
PubMed1980

Heterogeneous morphologic features of plaques induced by five strains of human cytomegalovirus.

Five strains of human cytomegalovirus (CMV) were examined in three human fibroblastic cultural systems with respect to plaque size and morphologic features. Plaques produced in cultures of fibroblastic cells from thyroid, and to a lesser extent in those from human embryonic skin-muscle tissue, had strain-associated morphologic differences that were stable on repetitive examination. The variations in morphologic characteristics of plaques appeared to reflect cytopathic changes, and the five strains could be separated on the basis of morphologic characteristics into two polar groups. Comparison of the sensitivities of three human fibroblastic cell lines for the detection of CMV revealed that one line was consistently inferior.

Antigens, Viral↗
PubMed1978

Immunodiagnosis of infection with Schistosoma mansoni: enzyme-linked immunosorbent assay for detection of antibody to circulating antigen.

A circulating antigen, a negatively charged polysaccharide from the trematode Schistosoma mansoni, was noncovalently bound to the surface of poly(L-lysine)-coated wells in polystyrene trays, which were then used in a micro-enzyme-linked immunosorbent assay (ELISA) test. The method provides an immunodiagnostic test for schistosomiasis of exceptional sensitivity with a high degree of specificity. Comparison of Bell egg counts and ELISA titers revealed a good correlation (r congruent to 0.80) in young individuals with low to moderate worm burdens, but this relationship was less marked in older individuals or those with high egg counts.

Animals↗