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Biomedical subjects

J Nanchahal

Publications and source records attributed to J Nanchahal.

14 recordsLinked to original sources
PubMed1992

New grafts for old? A review of alternatives to autologous skin.

Immediate resurfacing of skin defects is a challenging prospect, especially in patients with extensive full-thickness burns. Currently, split-thickness autografts offer the best form of wound coverage, but limited donor sites and their associated morbidity have prompted the search for alternatives. The application of allogeneic skin is restricted by availability and the risk of transmission of infection, whilst synthetic skin substitutes are simply expensive dressings. The problems of limited expansion may be overcome by culturing keratinocytes in vitro. Unlike autologous cells, allogeneic keratinocytes are available immediately, although they survive for less than a week when applied to full-thickness skin defects. Moreover, the absence of a dermal component in these grafts predisposes to instability and contracture. A cross-linked collagen and glycosaminoglycan dermal substitute, covered with thin split-skin grafts or cultured autologous keratinocytes, shows promise in burns patients. An alternative is a collagen matrix populated by allogeneic fibroblasts and overlaid with cultured autologous or allogeneic keratinocytes. The clinical application of cultured grafts remains imperfect but offers the prospect of immediate coverage and massive expansion.

Culture Techniques↗
PubMed1991

Ultrastructural localisation of anionic sites at the dermo-epidermal junction in normal human skin.

Glycosaminoglycans have been demonstrated throughout the cutaneous BMZ at the ultrastructural level. Colloidal iron and cationised ferritin proved of limited value, whilst staining with Alcian blue and application of the critical electrolyte concentration principle has provided evidence for the presence of sulphated GAGs at the lamina lucida and lamina reticularis. Digestions with chondroitin ABC lyase and heparin lyase have confirmed the existence of chondroitin and/or dermatan sulphates and heparan sulphates, although the results obtained with hyaluronate lyase have indicated that hyaluronates are also present.

Adult↗
PubMed1990

Dermal equivalents.

Explore the source record for details and available documents.

Artificial Organs↗
PubMed1989

Cultured composite skin grafts: biological skin equivalents permitting massive expansion.

After assessment in mice, a biological skin equivalent consisting of cultured fibroblasts in a collagen gel overlain with cultured keratinocytes was applied to three patients who had had tattoos excised. In all patients the grafts took well with good cosmetic results and little or no contracture. A biopsy at 4 weeks showed that the central graft area had a fully differentiated epidermis and a mature dermis without adnexae.

Adult↗
PubMed1989

Stretching skin to the limit: a novel technique for split skin graft expansion.

The premise underlying the meshed split skin graft that fragments of skin less than 1 mm wide are not viable is challenged, and a method is described for chopping split skin into fragments as small as 40 microns square. These tiny particles are viable and have been used to graft granulating wounds, achieving up to twenty-fold expansion without a decrease in the healing rate.

Adult↗
PubMed1987

Microscopic split-skin grafts: a new technique for 30-fold expansion.

Split skin was diced into 200 microns squares for use as a graft for large granulating wounds in pigs. "Diced" skin expanded 26-fold to give healing rates virtually identical with those obtainable with meshed split skin, despite a ten-fold difference in the area of donor skin used. The technique has been successfully applied in five patients with venous ulcers and seems to be a simple alternative to tissue culture for grafting extensive wounds.

Animals↗
PubMed1985

A study of the dermo-epidermal junction in dystrophic epidermolysis bullosa using the periodic acid-thiosemicarbazide-silver proteinate technique.

Dermo-epidermal separation in dystrophic epidermolysis bullosa (DEB) is thought to results from an abnormality of anchoring fibrils which, in normal skin, are stained selectively by the periodic acid-thiosemicarbazide-silver proteinate technique. This method was applied to non-lesional skin from four patients with generalized recessive DEB, five with localized recessive DEB and one with dominant DEB. No anchoring fibrils were present in the subjects with generalized recessive DEB, but they were morphologically normal in the case of dominant DEB and in three patients with mild localized recessive DEB. Two patients with a more severe form of localized recessive DEB possessed attenuated anchoring fibrils which lacked the normal banding of the mid-portion. The lamina densa, normally unlabelled, was consistently stained in patients with generalized recessive DEB, suggesting a biochemical abnormality of this structure.

Adolescent↗
PubMed1983

Periodate-labile structures at the normal human cutaneous basement membrane zone.

The distribution of carbohydrates containing 1,2-glycol groups at the basement membrane zones of the dermo-epidermal junction and dermal blood vessels was investigated using the periodic acid-thiosemicarbazide-silver proteinate technique. Controls included pre-incubation with dimedone, dimedone treatment both before and after periodate oxidation, and dimedone treatment followed by thiosemicarbazide and silver proteinate. At the dermo-epidermal junction the anchoring fibrils were stained selectively after both short (45 min) and long (71 h) thiosemicarbazide incubation periods, there being no staining of the lamina densa; however, the lamina densa surrounding blood vessels was labelled. After prolonged treatment with thiosemicarbazide, fibrils were observed traversing the lamina lucida at the dermo-epidermal junction, and collagen fibres were stained faintly. Pre-incubation with dimedone to block aldehyde groups did not affect the staining. However, when periodic acid treatment was omitted, or when sections were incubated with dimedone both before and after periodate oxidation, only melanin granules and the cytoplasm of fibroblasts were stained. Thus, anchoring fibrils are rich in carbohydrates containing 1,2-glycol groups susceptible to periodate oxidation, and correspond to the periodic acid Schiff-positive layer seen at the dermo-epidermal junction. Furthermore, the basement membrane zones of dermal blood vessels and the dermo-epidermal junction differ in their carbohydrate distribution.

Adult↗
PubMed1983

A method for processing light microscopy sections for oriented ultramicrotomy.

A simple technique is described for processing optical microscopy sections attached to glass slides for ultramicrotomy in any desired plane. A silicone rubber mold with a central orifice is clamped onto the slide so that the orifice overlies the section. Routine processing and embedding procedures are carried out in the well formed by the orifice.

Humans↗
PubMed1982

The healing of suction blisters in pig skin.

The healing of intact suction blisters in pig skin was studied using fluorescein-labelled lectins as well as conventional histological techniques. After blistering, initially overt separation was observed at the dermo-epidermal junction, but the separated epidermis appeared to re-attach within 9 h. Massive infiltration of the dermis and the epidermis by inflammatory cells, including eosinophils, was observed. By day 4 focal detachment of the epidermis occurred spontaneously, and towards day 9 the appearance of the blistered areas had almost returned to normal, apart from isolated patches of thin epidermis devoid of rete ridges. It is proposed that the sloughing the of the epidermis on day 4 is related to the presence of inflammatory cells and that the restoration of normal dermo-epidermal relations is dependent on the basement membrane zone remaining intact. The secondary blistering seen in day 4 specimens and the inflammatory cell involvement are in many ways similar to the blistering processes observed in certain human cutaneous disorders, such as dermatitis herpetiformis and bullous pemphigoid, and therefore suction blisters in pig skin might provide a suitable animal model for these diseases.

Animals↗