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Biomedical subjects

R M Taylor

Publications and source records attributed to R M Taylor.

At least 19 recordsLinked to original sources

Ceroid lipofuscinosis in the border collie dog: retinal lesions in an animal model of juvenile Batten disease.

Ceroid lipofuscinosis, an inherited disorder of lipopigment accumulation, was identified in a group of Border Collie dogs. The dogs developed mental, motor, and visual signs between age 15 and 22 months and progressed rapidly to severe neurological disease. The principal signs were blindness and gait and behavioural abnormalities with progressive dementia. Lipopigment accumulation was severe in neurones and glial cells of the central nervous system and was present in some visceral cells. Inclusions with variable ultrastructure were common in all cells of the retina, but the pigment accumulation did not damage the retinal architecture. The cytoplasmic inclusions were granular, sudanophilic, eosinophilic, and autofluorescent. Ultrastructural morphology varied, but fingerprint and curvilinear patterns predominated. The retinal lesions in the Border Collies were similar to those in English Setters with ceroid lipofuscinosis, but were much less severe than in juvenile human ceroid lipofuscinosis. This disorder bears a close resemblance to ceroid lipofuscinosis in English Setters and is another useful model for Batten's disease.

Animals

Amelioration of clinical disease following bone marrow transplantation in fucosidase-deficient dogs.

Canine fucosidosis was studied as an animal model for the treatment of neurovisceral lysosomal storage disease. Following successful bone marrow engraftment, dogs with fucosidosis had increased levels of alpha-L-fucosidase enzyme activity in leukocytes, plasma, and neural and visceral tissues. This widespread increase in enzyme activity was accompanied by a rapid improvement in the peripheral nerve and visceral lesions of fucosidosis and a more gradual improvement in the central nervous system pathology. Long-term engraftment from an early age reduced the severity and slowed the progression of clinical neurological disease. Transplantation after the onset of clinical signs was not effective. These findings suggest that the neurological damage caused by some inherited metabolic disorders, such as fucosidosis, may be preventable but emphasise the need for early diagnosis and treatment.

Animals

Zinc monoglycerolate--a slow-release source of therapeutic zinc: solubilization by endogenous ligands.

A combination of 65Zn-tracer determinations, oxidative analyses for glycerol, and a bioassay for uncomplexed Zn2+ have shown that: (i) zinc monoglycerolate (ZMG) dissolves in aqueous salt solutions/physiological media by dissociation into zinc ions and glycerol, but the rate and extent of ZMG dissolution depend upon pH, and/or concentration and complexing efficiency of zinc-ligands; (ii) under physiological conditions certain ligands present in skin and blood (e.g. citrate, lactate, albumin, histidine, glutathione and other thiols and, to a lesser extent, amino acids) accelerate ZMG dissolution; and (iii) there is a general correlation between the conditional stability constants (pH 7.3, 25 degrees C) of zinc-ligand complexes and the ability of given ligands to (a) solubilize ZMG in vitro and (b) mask the irritancy of Zn2+ in vivo. These observations indicate a mechanism for the transformation of ZMG applied transdermally or subcutaneously, to bioactive zinc (anti-arthritic nutritional supplement, etc.).

Animals

Research in social work practice: benefits of and obstacles to implementation in the Department of Veterans Affairs.

Although research is an important part of social work practice in health care, there is little systematic information that sheds light on research productivity, the benefits of conducting research, or the obstacles that must be overcome. This article represents the viewpoints of nearly all the directors of social services departments in the largest multihospital system in the United States, the Department of Veterans Affairs. The organizational characteristics of hospitals and the attitudes of the directors about research were important correlates of research productivity. Although lack of time, resources, and interest were cited as common obstacles, more than one-third of the departments were conducting or involved in at least one study. Information about the research efforts of other social services departments was considered an important resource, particularly for departments with no ongoing studies. The implications of these findings for social work research in health care are discussed.

Attitude

Culture of bovine pulmonary artery endothelial cells on Gelfoam blocks.

Conventional methods of endothelial cell culture on monolayers and beads require enzymatic digestion, traumatic scraping, or centrifugation to transfer cells to other experimental systems. Gelfoam, a porous gelatin block, not only supports the growth of bovine pulmonary artery endothelial cells but also allows the rapid transfer of cell-laden blocks from one experimental system to another with minimal intervention. This property has been shown to be especially useful for the rapid fixation of endothelial cells for microscopy using standard histologic methods. Histology confirmed that the trabecular nature of the substrate allows endothelial cells to line the interstices of the sponge matrix and grow in a configuration that simulates the appearance of the endothelium in small vessels and capillaries. The inoculation of 1 x 10(5) endothelial cells on 7.5 mg Gelfoam (24 x 8 x 2 mm blocks) was enhanced by fibroblast growth factor and resulted in cell attachment by day 2 with a cell doubling time of 1.7 days. In addition, endothelial cells completely infiltrated 1, 5 and 7.5 mg Gelfoam blocks, as verified by histology. Assays to quantify cell number and protein were easily performed. To facilitate cell counting, the Gelfoam matrix was rapidly removed by the addition of 0.05 mg/ml collagenase, a concentration that interfered minimally with the assay for cellular protein concentration. The data demonstrate that Gelfoam is a suitable support growth matrix for the in vitro culture of bovine pulmonary artery endothelial cells.

Animals

Improved graft outcome and reduced complications due to flow cytometric crossmatching and DR matching in renal transplantation.

Several previous studies, including our own, have indicated that flow cytometric assays can identify an at-risk population of kidney transplant recipients. We used the assay for recipient selection for a period of twelve months. Recipients with donor T cell-directed IgG were excluded from transplantation and those with B cell-directed IgG were treated with increased immunosuppression. The transplants performed over this period (n = 126) were compared with an earlier series (n = 118) where, although the flow cytometric crossmatches were performed, the results did not influence patient management. In the series where the flow cytometric crossmatch was used in management, a lower failure rate was found at three months (P = 0.037 chi square), primary non-function was reduced (P less than 0.0001, Mann-Whitney), rejection episodes were reduced (P less than 0.0001, Mann-Whitney) and the hospital stay was shorter (P less than 0.0001, Student's t). The risk factors of ischemic times, panel reactivity, exposure to previous grafts and A/B locus matching were identical between the two groups. However DR matching was found to be higher in the series with the improved results (P less than 0.0001, Mann-Whitney). In view of the significant improvement in graft success and low complication rate, we intend to continue with the policy of recipient selection by flow cytometric crossmatching and DR matching.

Adult

Renal allograft rejection: induction and function of adhesion molecules on cultured epithelial cells.

The interaction of graft-infiltrating immune cells with donor parenchymal cells is an important early event in allograft rejection. This binding is stabilized by interaction of antigen-independent 'adhesion' molecules expressed on the two cell types. As the level of expression of these molecules can be altered during inflammation, a series of experiments was performed to examine the effects of the inflammatory cytokines interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) on adhesion molecules expressed by cultured human renal tubular epithelial cells. These cells constitutively expressed ICAM-1 and LFA-3. Incubation with IFN-gamma increased expression of ICAM-1 but had no significant effect on expression of LFA-3 (P greater than 0.05). Incubation with TNF-alpha increased expression of both ICAM-1 and LFA-3; IFN-gamma synergized with TNF-alpha to further augment expression of these molecules. Peripheral blood lymphocytes (PBL) showed an enhanced binding to allogeneic renal epithelial cell monolayers which had been pretreated with IFN-gamma or TNF-alpha. MoAbs specific for ICAM-1 or its ligand LFA-1 inhibited adhesion of PBL to either IFN-gamma- or TNF-alpha-pretreated renal cells. By contrast, antibodies specific for LFA-3 or its ligand CD2 only significantly blocked PBL adhesion to renal cells which had been pretreated with TNF-alpha. Combination of antibodies specific for multiple components of the adhesion systems produced greater inhibition of adhesion than was produced by any single MoAb. These results suggest that the inflammatory cytokines IFN-gamma and TNF-alpha up-regulate expression of functional ICAM-1 and LFA-3 molecules which can augment the binding of potentially graft-damaging lymphoid cells to renal tubular epithelial cells.

Antigens, CD

A simple, quantitative method for assessing angiogenesis and antiangiogenic agents using reconstituted basement membrane, heparin, and fibroblast growth factor.

BACKGROUND: Blood vessel growth is necessary for normal tissue homeostatis and contributes to solid tumor growth. Methods to quantitate neovascularization should be useful in testing biological factors and drugs that regulate angiogenesis or to induce a vascular supply to promote wound healing. EXPERIMENTAL DESIGN: An extract of basement membrane proteins (Matrigel) was found to reconstitute into a gel when injected subcutaneously into C57/BL mice and to support an intense vascular response when supplemented with angiogenic factors. RESULTS: New vessels and von Willebrand factor antigen staining were apparent in the gel 2-3 days after injection, reaching a maximum after 3-5 days. Hemoglobin content of the gels was found to parallel the increase in vessels in the gel allowing ready quantitation. Angiogenesis was obtained with both acidic and basic fibroblast growth factors and was enhanced by heparin. Several substances were tested for angiostatic activity in this assay by coinjection in Matrigel with fibroblast growth factor and heparin. Platelet-derived growth factor BB, interleukin 1-beta, interleukin-6, and transforming growth factor-beta were potent inhibitors of neovascularization induced by fibroblast growth factor. Tumor necrosis factor-alpha did not alter the response but was alone a potent inducer of neovascularization when coinjected with Matrigel and heparin. Consistent with the previously demonstrated importance of collagenase in mediating endothelial cell invasion, a tissue inhibitor of metalloproteinases that also inhibits collagenases was found to be a potent inhibitor of fibroblast growth factor-induced angiogenesis. CONCLUSIONS: Our assay allows the ready quantitative assessment of angiogenic and anti-angiogenic factors and should be useful in the isolation of endothelial cells from the capillaries that penetrate into the gel.

Angiogenesis Inducing Agents

Availability of transplantable organs from brain stem dead donors in intensive care units.

OBJECTIVE: By audit from January to June 1989 to quantify, separately for hearts, kidneys, liver, lungs and corneas, the possible increases in transplantable organs from brain stem dead potential donors in intensive care units and to compare them with the increases achieved in October-November 1989, during intense, national publicity about transplantation. DESIGN: Prospective audit of all deaths in intensive care units in England from 1 January to 30 June 1989 and subsequent case study of the impact of publicity on offers and donations during October-November 1989. SETTING: 15 regional and special health authorities in England. PATIENTS: 5803 patients dying in intensive care units, of whom 497 were confirmed as brain stem dead and had no general medical contraindication to organ donation. MAIN OUTCOME MEASURES: Organ specific suitability for transplantation (as reported by intensive care units); consent for donation of specific suitable organs; and procurement of specific organs reported as suitable for transplantation and offered. RESULTS: In the 497 (8.6%) brain stem dead potential donors were estimated the organ specific suitability for heart as 63%, kidneys 95%, liver 70%, lungs 29%, and corneas 91%. Refusal of relatives (30%) accounted for major losses of suitable organs of all types. For kidneys the loss was equivalent to 44% of brain stem dead actual kidney donors. No discussion of organ donation was the second most important reason for missed kidney donors, the loss being equivalent to 10% of brain stem dead actual donors. Non-procurement or difficulties with allocating organs was the second most notable cause of missed suitable liver and lung donors; 29% (55) of the offered total of 189 liver donors and 27% (21) of 78 offered suitable lung donors in six months. Non-procurement of suitable, offered organs was rare for kidneys and modest, of the order of 13% and 10% respectively, for heart and corneas. Corneal donation from brain stem dead potential donors might be improved nearly as much (that is, a 78% increase in brain stem dead actual corneal donors) by specific measures to promote corneal donation when other organs are offered as by reducing the overall refusal rate. Restricted offers, non-procurement, and no discussion of donation accounted for nearly equal numbers of lost donations of hearts (each equivalent to 15% of donated hearts). During October-November 1989 when there was intense, positive publicity about transplantation the rates of refusal and non-discussion fell compared with during January-June (22%, 36/163 v 30%, 138/460; 7%, 33/497 v 2%, 4/167 respectively). Offers of suitable donors increased significantly (p less than 0.02) compared with the first six months of 1989, most notably for heart donors (80 v 60.1 expected) and kidney donors (122 v 102.1 expected) but only for kidneys was there a noticeable 17% increase in actual donors (118 actual audited donors v 100.8 expected donors; p = 0.09). CONCLUSIONS: Four strategies to increase the supply of transplantable organs from brain stem dead potential donors in intensive care units were identified: (a) reducing refusal of relatives (b) avoiding non-procurement of actually suitable organs (by logistical initiatives) and deterioration of initially suitable organs (by donor care initiatives); (c) converting restricted offers to unrestricted offers; and (d) ensuring discussion with families. Early referral to the transplant team or coordinator gives time for discussion about donor care and agreement on medical suitability for donation of specific organs. Solving some of the logistical problems of non-procurement may be a prerequisite for increased offers to be translated into increased donations. The impact of publicity therefore needs to be measured on offers of suitable donors as well as by actual donations.

Brain Death

Renal epithelium: reversal of cytotoxic damage by addition of anti-thymocyte globulin.

A novel in vitro assay of renal epithelium tight junction function was used to assess the efficacy with which rabbit anti-thymocyte globulin (ATG) blocks epithelium damage mediated by lymphokine-activated killer (LAK) cells. It was found that LAK cells lysed renal epithelial cells poorly in standard chromium-release assays but that they caused a rapid, and almost total, reduction in trans-epithelium monolayer resistance, indicating tight junction failure and, hence, loss of tissue function. LAK cell-mediated cytolysis of the sensitive K562 cell line was completely blocked in the presence of ATG at a concentration of 200 micrograms/ml. Addition of ATG at this concentration to damaged renal cell monolayers in the presence of LAK cells allowed the trans-monolayer resistance to recover rapidly to levels approaching the values recorded before initial addition of LAK cells. On this basis it seems likely that the rapid restoration of renal function frequently observed after appropriate "rescue" therapy during episodes of acute rejection may reflect subtle changes in tissue function rather than recovery from widespread graft cell cytolysis.

Animals

Management of duodenal injuries by proximal T-tube drainage.

Duodenal injuries may be caused by blunt or penetrating trauma. There is a high mortality rate with this type of injury, particularly when associated with pancreatic trauma. The surgical management of such injuries is difficult and a technique is described which may reduce postoperative morbidity, as illustrated by the two cases described.

Accidents, Traffic

Monoclonal and polyclonal antibodies: clinical aspects.

Over the years, the ways in which the antibodies ATG and OKT3 have been used in clinical transplantation have changed. ATG was first on the scene and has been used as initial immune suppression in certain forms of transplantation, of which cardiac transplantation is one good example. It has not been commonly used in renal transplantation, but there is evidence that this may be changing. The nephrotoxic side-effects of cyclosporin continue to cause anxiety, and high rates of initial non-function of kidney allografts have made early management difficult; this may have contributed to some early graft failures. There is currently interest in avoiding the use of cyclosporin initially by commencing immune suppression treatment with ATG, in an attempt to improve the immediate function rate of kidney grafts. When function is established, more conventional treatment schedules, usually with cyclosporin A, are introduced. ATG is also being incorporated in basic immunesuppressive regimes as part of multiple drug treatments. The hypothesis of multiple drug treatments is based on the idea that if a number of different immune suppressive agents are used, then the dose of each may be reduced, with minimisation of side-effects. This concept may be true, but the price may be that of an increased rate of malignancy in the long-term graft recipients.(ABSTRACT TRUNCATED AT 250 WORDS)

Antilymphocyte Serum

Neuroleptic malignant syndrome: occurrence in a child after reconstructive surgery.

The occurrence of the rare but potentially fatal neuroleptic malignant syndrome must be considered by the surgeon treating a patient who develops hyperthermia, mental abnormalities, autonomic instability, and muscle rigidity after exposure to phenothiazines or other neuroleptic drugs. The dopamine agonist bromocriptine appears to be the treatment of choice in adults and seemed to be effective and well tolerated in our patient. Although the syndrome cannot be prevented, recognition is crucial, since effective general and specific therapy is available. Differentiating neuroleptic malignant syndrome from malignant hyperthermia allows early appropriate treatment with bromocriptine.

Child