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Biomedical subjects

B Hull

Publications and source records attributed to B Hull.

At least 19 recordsLinked to original sources
PubMed2001

Cooperative transformation and coexpression of bovine papillomavirus type 1 E5 and E7 proteins.

Productively infected bovine fibropapillomas were examined for bovine papillomavirus type 1 (BPV-1) E7 localization. BPV-1 E7 was observed in the cytoplasm of basal and lower spinous epithelial cells, coexpressed in the cytoplasm of basal cells with the E5 oncoprotein. E7 was also observed in nucleoli throughout the basal and spinous layers but not in the granular cell layer. Ectopic expression of E7 in cultured epithelial cells gave rise to localization similar to that seen in productive fibropapillomas, with cytoplasmic and nucleolar expression observed. Consistent with the coexpression of E7 and E5 in basal keratinocytes, BPV-1 E7 cooperated with E5 as well as E6 in an anchorage independence transformation assay. While E5 is expressed in both basal and superficial differentiating keratinocytes, BPV-1 E7 is only observed in basal and lower spinous epithelial cells. Therefore, BPV-1 E7 may serve to modulate the cellular response of basal epithelial cells to E5 expression.

Animals↗
PubMed1999

L20B cells simplify culture of polioviruses from clinical samples.

Culture of polioviruses from clinical samples is the gold-standard method for virological surveillance in the world-wide initiative to eradicate wild-type polioviruses. Two poliovirus-sensitive cell lines of human origin were used originally by the laboratories of the World Health Organisation (WHO) global poliovirus network. However, the cell lines used, Hep2 and RD, also support cytopathic growth of a variety of non-poliovirus enteroviruses. This can make detection of polioviruses in samples with mixtures of viruses difficult and time consuming. The development of mouse cell lines that express the gene for the human cellular receptor for polioviruses allows selective poliovirus culture, because very few non-poliovirus enteroviruses grow in these murine cells. A WHO Collaborative Study was initiated to test one such cell line, L20B, and to compare under routine conditions the sensitivity and selectivity of L20B cells against RD and Hep2 cells. Five laboratories in countries endemic or recently endemic for wild polioviruses participated. A total of 425 samples were tested prospectively in all three cell lines and there was a clear and consistent trend for greater sensitivity for polioviruses in L20B cells. Overall, 148/160 polioviruses were detected in L20B cells compared with 89/160 in RD and 98/ 160 in Hep2. In part, this finding was due to detection in L20B cells of polioviruses from samples that also contained non-poliovirus enteroviruses in which the poliovirus was masked in RD or Hep2 cells. However, L20B cells were also significantly more sensitive for poliovirus than either RD or Hep2 cells in three of the five study laboratories. The L20B cells were completely selective for polioviruses, as 0/89 wild type non-poliovirus enteroviruses produced cytopathic effect in L20B cells. Finally, L20B cells provided a diagnosis of poliovirus infection in the same time as RD and Hep2 cells from samples that contained poliovirus only, but substantially more quickly for samples that contained another enterovirus. Taken together, these data indicate that L20B cells simplify primary diagnosis of poliovirus from clinical samples and as a result they have been introduced for routine use by laboratories of the WHO global poliovirus network.

Animals↗
PubMed1995

Health status and exposure of workers at a pilot brown coal liquefaction plant in Australia, 1985-1991.

In 1985, Brown Coal Liquefaction (Victoria) Pty Ltd (BCLV) commenced operation of a pilot plant that investigated the feasibility of producing oil from brown coal. The plant operated for five years. This study aimed to use exposure and health information routinely collected by the company to characterize various health parameters of the workforce and to investigate whether any adverse health measures were exposure-related. About 1680 persons were employed at some time or other by BCLV, and the primary study population consisted of 408 workers who had a medical examination at the end of employment and who consented to being in an epidemiological study. Reported photosensitivity was associated with higher cumulative skin exposure (RR = 1.85; 95% CI = 1.22-2.78), with an exposure-response relationship of increasing risk with increasing skin exposure being suggested. There was no consistent evidence that chemical exposure at BCLV had any negative effect on the haematological, biochemical, endocrine or lung function of workers at the plant. However, the maximum follow-up period of less than eight years limits the ability of the study to detect any emerging chronic effects.

Adult↗
PubMed1990

A study of HTLV-I and its associated risk factors in Trinidad and Tobago.

Seroprevalence of human T-lymphotropic virus type 1 (HTLV-I) among a sample of persons selected from a government register of businesses in Trinidad was 3.2% in 1,025 persons of African descent compared to 0.2% among 487 persons of Asian descent and 0% among 46 persons of European-descent. In Tobago, from a coastal village, among persons of African ancestry ascertained as part of a cardiovascular survey, the rate was 11.4%, which was significantly higher when corrected for age and race than the rate in Trinidad. The seroprevalence rate of antibodies to hepatitis A and B was also significantly elevated in Tobago compared to Trinidad. HTLV-I seroprevalence rates were higher in females than males while hepatitis A and B rates were not significantly different in the two sexes. For males, age was a significant determinant of HTLV-I seropositivity, while for females, age, markers of poor sanitation, and hepatitis B were each independently linked to HTLV-I seropositivity. The frequent occurrence of multiple infectious exposures in persons of lower socioeconomic circumstances in this tropical environment may result in immune activation that heightens susceptibility to HTLV-I infection.

Adult↗
PubMed1989

An outbreak of acute flaccid paralysis in Jamaica associated with echovirus type 22.

An outbreak of acute flaccid paralysis in Jamaica in 1986 associated with echovirus type 22 is described. Six patients aged 1 to 27 years developed acute onset of severe flaccid paralysis, with inability to walk. Three cases had facial weakness, four required intensive care with assisted ventilation, and two died. Echovirus type 22 was isolated from the stool of two patients who showed a significant increase in antibody titre. Echovirus type 22 was also isolated from the stool of another patient who had aseptic meningitis without any neurological deficit. There was no evidence of poliovirus infection in any of these patients, most of whom were fully immunized. Of the four surviving cases with flaccid paralysis, three had residual weakness in their lower limbs and walked with an abnormal gait 3 years after the acute paralytic attack. This is the first report in the literature of acute flaccid paralysis associated with type 22 echovirus.

Acute Disease↗
PubMed1989

Epidemiology of AIDS and HIV infection in the Caribbean.

A review of surveillance data on AIDS and HIV infection in the 18 English-speaking Caribbean countries and Suriname suggests that the epidemiologic pattern of AIDS in the Caribbean is evolving from an epidemic that began in 1983 among homosexual and bisexual males to one in which cases are increasingly resulting from heterosexual contact, with different countries at various stages of transition. Overall, there has been a decline in the male to female case ratio. Perinatal transmission is already a major problem in many countries--19% of cases in the Bahamas are among children under 15 years of age. Serosurveys conducted in Trinidad and Tobago, Jamaica, Antigua, St. Vincent and the Grenadines, and other countries show high HIV seroprevalence among homosexuals (15-40%), prisoners (4-10%), prostitutes (up to 13%), and cocaine users (2%); at present, prevalence in the general population continues to be low.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Polio immunization and serological status in children and adolescents in Jamaica (1985).

A survey of immunization status and serological immunity to polio was carried out in 5 parishes in Jamaica in 1985. A sample of 2,506 children and adolescents aged 1-19 years was chosen by selecting clusters of children in enumeration districts (EDs) in each parish from the 1980 Census. Immunization status was verified by examining immunization records. Serological assay for antibodies to Polio Types 1, 2, and 3 was done. A positive neutralization test at dilution of 1:8 was taken as immunity to the polio virus. Of the 1,819 children whose immunization status was confirmed, coverage with 3 or more doses of oral polio vaccine was highest in the 1-4 year age group with 79.7% and lowest in the 15-19-year age group with 37.4%. Of the 2,506 children 81.4%, 94.7% and 72.3% were seropositive for Polio Types 1, 2 and 3 respectively. There was a significant difference in the prevalence of seropositives between individuals with and those without a history of vaccinations. No urban/rural or sex differences were noted. The study indicated a higher level of immunization status than previous surveys and a high level of serological immunity to polio.

Adolescent↗
PubMed1986

Hemolysis, elevated liver enzymes, and low platelet count syndrome: nursing care of the critically ill obstetric patient.

Although patients with severe preeclampsia and eclampsia are infrequently admitted to critical care areas, it is important that the critical care nurse be aware of the HELLP syndrome. The case presentations demonstrated hemolysis, liver dysfunction, and abnormal platelet consumption. Knowledge of the clinical and laboratory findings will assist in nursing assessment and intervention for these critically ill obstetric patients.

Acute Disease↗
PubMed1984

Natural transovarial transmission of dengue 4 virus in Aedes aegypti in Trinidad.

The isolation of dengue 4 virus from adult Aedes aegypti, reared from eggs collected in nature, is reported for the first time. From the locality where the isolate was made, 25 pools consisting of 1,848 Ae. aegypti reared from eggs were processed. In this study, 10 different localities were sampled and a total of 10,957 Ae. aegypti adults, collected as eggs or larvae in nature, were processed for virus isolation. From a total of 158 mosquito pools tested, one recovery of dengue 4 virus was made. The isolation of dengue 4 virus from this field-collected material gives further evidence that transovarial transmission of dengue viruses occurs in nature.

Aedes↗
PubMed1984

The living skin-equivalent as a structural and immunological model in skin grafting.

The living skin equivalent is a tissue formed when self-assembled collagen fibrils are contracted by fibroblasts. The rate and extent of volume contraction is proportional to the number of cells incorporated into the lattice. The fibroblasts are biochemically active in the lattice, synthesizing collagen and adding it to the matrix. This compacted lattice provides a substrate allowing attachment of keratinocytes and the formation of a multilayered keratinized epidermis with a basement lamella. When a skin equivalent grafted to a recipient animal is wounded, it is capable of wound contraction and repair. Because of the simplified character of the skin equivalent it may offer a useful model for studying wound healing. During the initial healing of the grafted skin equivalent, fibroblasts from the skin equivalent move freely into the surrounding tissue. Karyotyping of fibroblasts grown from skin surrounding the skin equivalent graft shows that fibroblasts from the graft migrate at least 6-9 mm from the graft edge. At 3-6 mm from the graft edge about 50% of the fibroblasts present are of donor origin. Fibroblasts also migrate from allogenic skin grafts before these grafts are rejected. At 3-6 mm from the scar left by the rejected graft 36% of the fibroblasts are of donor origin 2 months after grafting. The skin equivalent model provides a well-defined system for studying transplantation reactions. Results obtained on persistence of allografted fibroblasts support our theory that in the rat, the fibroblast is antigenically neutral.

Animals↗
PubMed1983

The reconstitution of living skin.

A living-skin equivalent useful as a skin replacement and as a model system for basic studies has been fabricated and tested extensively. It consists of two components: (1) a dermal equivalent made up of fibroblasts in a collagen matrix that is contracted and modified by the resident cells, and (2) an epidermis that develops from keratinocytes "plated" on the dermal equivalent. A multilayered keratinizing epidermis with desmosomes, tonofilaments, and hemidesmosomes forms. Basement lamella formation occurs within 2 weeks in vitro when rat cells are used. With human cells, crypt or pseudofollicular morphogenesis is observed in vitro within 3 weeks after plating cells on the dermal equivalent. Autografts and isografts of rat-skin equivalents made with cultured cells from biopsies are rapidly vascularized, block wound contraction, and persist essentially for the lifespan of the host. Seven to 9 days after grafting, donor cells become activated biosynthetically and mitotically. By 1 year, the dermal population decreases to a normal level and the matrix has been extensively remodeled. The grafts remain free of hair and sebaceous glands. Grafts to rats have been in place for over 2 years. Now, allografts of dermal equivalents have been made across a major histocompatibility barrier and are not rejected. The persistence of cellular elements of the grafts is monitored by use of a genetic marker. Challenge of the allograft with a second skin-equivalent graft after 1 month does not result in rejection of the original graft or of the second skin-equivalent graft. We propose that allografts of tissue equivalents are tolerated because cells with class II antigens are selected against during in vitro cultivation and are excluded from the graft. Thus the fabrication of skin-equivalent tissues or of other equivalent tissues with parenchymal cells that do not bear class II antigens may render transplants of such tissues immunologically acceptable despite the presence of allogeneic cells. The capacity to graft across major histocompatibility barriers using living tissue equivalents may have important clinical significance.

Animals↗
PubMed1981

Regulation of proliferation of fibroblasts of low and high population doubling levels grown in collagen lattices.

While IMR 90 and AG 1519 fibroblasts of low and high population doubling levels grow to confluency when plated on plastic surfaces, they cease to divide within four days when incorporated into collagen lattices. Growth inhibition in the lattices is not due to exhaustion of the medium or isotope, or to contact inhibition; nor is it due to impermeability of the lattice to the materials in the medium. While cells in a lattice arrest in G0, this state is reversible when cells are permitted to leave the lattice and populate a plastic substrate. We conclude that fibroblasts in tissue-like lattices may be responsive to some of the same controls as cells in connective tissues.

Animals↗