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Biomedical subjects

I McKay

Publications and source records attributed to I McKay.

12 recordsLinked to original sources

Generation and selection of monoclonal antibodies, single-chain Fv and antibody fusion phage specific for human melanoma-associated antigens.

A panel of 13 murine monoclonal antibodies (mAbs) recognizing antigens on human melanoma cells but not on melanocytes was generated. Two mAbs (LHM3 and LHM5) stained sections of melanoma but not normal tissues. mAbs LHM2 and LHM8 stained only a minority of normal tissues. The mAbs differed further in their staining patterns on melanoma cell lines HMB2, DX3 and SK23 in FACS. The mAbs recognize antigens of 34, 38, 57, 94, 190-200 and > 200 kD. One mAb each bound to each of the antigens HLA DR (LHM4) and high molecular weight proteoglycan (LHM2). The high molecular weight proteoglycan-specific mAb was used to construct a single-chain Fv (scFv) antibody fragment and an antibody fusion phage in Escherichia coli. Both the scFv and the fusion phage were shown to bind specifically to melanoma cells. A method for the selection of melanoma cell-binding phages from phage libraries is described.

Animals

Reconstruction of human skin from glycerol-preserved allodermis and cultured keratinocyte sheets.

The aim of this project was to reconstruct human skin from glycerol-preserved dermis and layers of cultured keratinocytes for use in the treatment of deep burns and ulcers. Glycerol-preserved cadaver skin from the Euro Skin Bank was treated with Dispase II or PBS, under various conditions, to find the best method of retaining the physical structure of the dermis while removing the epidermis and remnants of dead dermal cells which might provoke an allogeneic reaction in a graft recipient. Monoclonal antibodies LH39 and LH7.2, with specificity for basement membrane determinants, showed that treatment with Dispase II resulted in separation of the epidermis from the dermis with concomitant loss of all cellular elements from the dermal layer (as judged by H and E staining). However, when sheets of cultured keratinocytes were applied to the treated dermis and cultured for several days, the keratinocytes attached and regenerated a new basement membrane.

Cells, Cultured

Clinical practice and biological effects of keratinocyte grafting.

Skin grafts can be produced in the laboratory from simple sheets of cultured keratinocytes (keratinocyte grafts) or in combination with different mixtures of connective tissue components (composite culture grafts). Autologous keratinocyte grafts have been used most extensively in patients with major body surface burns and have proved life saving. Further attention to clinical factors has improved graft take to 50-60% in optimal circumstances although there is some short term instability of the graft. Keratinocyte autografts can also be used to treat other chronic wounds such as leg ulcers, and surgical excisions. Keratinocyte allografts do not survive transplantation but have effects on wound healing by the release of growth factors and matrix components. Composite grafts have been little used in clinical practice and there are inherent problems with the stability of the matrix components in the presence of high levels of wound collagenases, but banks of allogenic skin grafts may provide temporary cover in burns patients. The roles and clinical indications for keratinocyte grafting are now becoming clear following wider clinical experience.

Cells, Cultured

Typing of Clostridium difficile causing diarrhoea in an orthopaedic ward.

In an outbreak of diarrhoeal disease in an orthopaedic ward Clostridium difficile was isolated from all six patients with diarrhoea. Attempts were made to type these isolates by means of antibiogram, detection of pre-formed enzymes, analysis of surface proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting, and plasmid profile analysis. This showed that a single strain (type E) indistinguishable by the four distinct methods of typing, was isolated from all six patients at some time during their episodes of diarrhoea. Relapse was caused by the acquisition of a new strain in two patients, and by re-emergence or reacquisition of the original strain in two patients. The immunochemical method was the most sensitive and discriminatory of the typing strategies adopted.

Aged

Scintigraphic evaluation of the painful prosthetic joint: a comparison of gallium-67 citrate and indium-111 labelled leucocyte imaging.

The radiopharmaceuticals gallium-67 and indium-111 labelled leucocytes have been compared in 15 patients with a painful joint prosthesis in an attempt to identify those patients with periprosthetic infection. Gallium-67 images were abnormal in five out of six patients with periprosthetic infection and normal in seven out of nine without evidence of infection. Indium-111 leucocyte images were abnormal in three out of six patients with infection and normal in all nine patients without infection. Indium-111 labelled leucocyte imaging is technically more difficult to perform than gallium-67 imaging. This, combined with the higher sensitivity of gallium-67 imaging for infection around a prosthetic joint, leads us to conclude that gallium-67 imaging is superior to indium-111 leucocyte imaging in identifying infection as a cause of a painful prosthetic joint.

Adult

An inhibitory effect of tumour promoters on human epithelial cell growth can be dissociated from an effect on junctional communication.

Studies with rodent cells have indicated that the abilities of various tumour promoters to inhibit metabolic cooperation correlate with their potencies as mitogens. Here we have examined the effects of the most potent phorbol ester tumour promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), on metabolic cooperation and growth of human epidermal cells transformed by SV40 (SVK14 cells). In this system, TPA inhibits junctional communication and at the same concentration also inhibits growth in a reversible fashion. These effects appear to be mediated by binding of phorbol ester to a single class of high affinity binding site with a Kd similar to that reported for rodent cells (Kd = 20.9 nM at 4 degrees C). Further studies on the effects of phorbol esters on other human epithelial cell lines reveal that the inhibitory effects of TPA on growth and metabolic cooperation may be completely dissociated. Alternative mechanisms by which TPA may exert its growth-inhibitory effects are discussed.

Breast Neoplasms

Nail elevator.

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Finger Injuries

Normal p21N-ras couples bombesin and other growth factor receptors to inositol phosphate production.

Many receptors, in response to ligand activation, trigger inositol phospholipid breakdown, which leads to rapid intracellular responses. The sustained activation of this pathway is believed to be at least one of the factors involved in the stimulation of cell growth and there has been much speculation that certain oncogenes use this pathway to effect uncontrolled cellular proliferation. It has been suggested, by analogy with the receptor-mediated control of adenylate cyclase, that the receptor stimulation of inositol phospholipid metabolism is mediated through a guanine nucleotide regulatory protein (G-protein) called Gp (or Np). Although such a species has not been identified, there is now strong experimental evidence that this process is mediated by a G-protein distinct from the stimulatory and inhibitory G-proteins (Gs and Gi, respectively). The ras genes code for a plasma membrane protein, p21, whose only known biochemical property is a high-affinity GTPase activity. We show here that the expression of normal p21N-ras in NIH 3T3 fibroblasts leads to the coupling of certain growth factor receptors to stimulated inositol phosphate production. We propose that the N-ras proto-oncogene encodes a protein which couples the receptors for certain growth factors to the stimulation of phospholipase C. Thus, N-ras p21 may be the putative Gp or a functionally related protein.

Animals