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Biomedical subjects

B Hull

Publications and source records attributed to B Hull.

33 records · Page 2Linked to original sources
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↗
PubMed1981

Development and use of a living skin equivalent.

We have developed a living skin equivalent, which serves as a skin substitute in experimental animals. On application it is rapidly vascularized, it inhibits wound contraction, and it is immunologically tolerated and persists for as long as it is allowed to remain in place. It comes to resemble normal skin, although it lacks secondary derivatives, the cells for which may in time be available for incorporation into the fabricated tissue.

Animals↗
PubMed1979

Serological evidence of dengue virus activity in children on the Northern Leeward Islands (Netherlands Antilles).

An arbovirus serologic survey of school children on the Northern Leeward Islands (Saba, St. Eustatius and St. Maarten) using haemagglutination inhibition (HI) detected a high proportion of reactors to dengue types 1,2, and 3. Analysis in relation to age showed an increasing proportion to be positive with increasing age. The results of an all-age survey on St. Eustatius 1970 led to the hypothesis of possible dengue serotype 1 activity on St. Eustatius around 1900, whilst it is thought that dengue type 2 was endemic at other times. In view of the continuous high endemic dengue activity the (re)-appearance of dengue serotype 1 next to type 2 and 3 may be the prelude to the occurrence of the dengue shock syndrome.

Adolescent↗
PubMed1978

Serologic survey of dengue and other arboviruses in Curaçao and Aruba, 1973.

Sera obtained principally from children on the Caribbean islands of Aruba and Curaçao were tested for antibodies to various arboviruses. The test indicated that dengue 2 was endemic on Curaçao but not on Aruba, perhaps because of more effective vector control measures on Aruba. Neutralization tests performed with a samll number of sera suggest that dengue infections may have afforded some level of protection against yellow fever to a portion of the Curacao population.

Adult↗
PubMedDate not supplied

Sylvatic yellow fever activity in Trinidad, 1988-1989.

Of a total of 18,068 mosquitoes (361 pools) collected in south-eastern Trinidad forests from December 1988 to May 1989, 47 species belonging to 14 genera were identified. Five yellow fever virus isolates were made from Haemagogus janthinomys and one from Sabethes chloropterus. All the other pools of mosquitoes examined were negative for the virus. The mosquito isolates were made in December and January. In addition, in late February and early March, 2 infected howler monkeys (Alouatta sp.) were detected. Since March, despite continued surveillance, no yellow fever virus has been detected in mosquitoes or monkeys. There has been no reported human infection.

Alouatta↗