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Biomedical subjects

M Cooper

Publications and source records attributed to M Cooper.

At least 145 records · Page 8Linked to original sources
PubMed1994

Stored skin--stored trouble?

Quantitative bacteriology is presented on 102 consecutive split-skin grafts. A sample of graft was cultured whenever skin was taken and whenever stored skin was used. Stored skin unused at 21 days was also cultured. The percentage take of grafts was inversely proportional to number of organisms/g of skin (r = -0.24, p < 0.05). Commonly used storage conditions facilitated bacterial multiplication. There was no significant difference in organisms/g contaminating grafts for different surgeons, skin preparations, types of grafts, cutting tools or mode of anaesthesia. Male patients had a significantly greater count for initial grafts (p = 0.02), but after 3 weeks storage there was no sex difference.

Adolescent↗
PubMed1994

Simultaneous 60-electrode mapping of ventricular tachycardia using percutaneous catheters.

OBJECTIVES: We developed a new approach for mapping ventricular tachycardia at electrophysiologic study using simultaneous recordings from up to 60 catheter electrodes. BACKGROUND: Good results for surgical or catheter ablation of ventricular tachycardia are limited by the ability to detect and completely map all of the underlying arrhythmogenic areas. Currently, catheter mapping of all configurations of ventricular tachycardia is impossible or unsatisfactory in at least 60% of patients because of poorly tolerated rapid rates, nonsustained ventricular tachycardia or multiple configurations. METHODS: Twenty-four patients with recurrent ventricular tachycardia refractory to antiarrhythmic drugs were studied using up to six percutaneous decapolar catheters introduced into the ventricles. Left ventricular maps of ventricular tachycardia were achieved by two to three transseptal catheters, two to three transaortic catheters, a coronary sinus catheter and right ventricular catheters. Simultaneous endocardial maps of either right or left ventricles were possible with a resolution of approximately 1 to 2 cm. Up to 60 electrograms were digitized and recorded simultaneously using a custom-computerized mapping system. RESULTS: Successful maps of 73 ventricular tachycardia configurations were obtained in 22 patients. The mapping procedure failed in two patients because of inability to catheterize the left ventricle in one and inability to induce monomorphic ventricular tachycardia in the other. The mean (+/- SD) ventricular tachycardia cycle length was 285 +/- 53 ms (range 215 to 470). A total of 39 separate arrhythmogenic areas (median 1, interquartile [25% to 75%] range 1 to 3/patient) were detected, of which 21 (54%) were in the left ventricular free wall, 17 (44%) were in the ventricular septum, and 1 (2%) was in the right ventricular outflow tract. Ten patients (45%) had at least two arrhythmogenic areas. Thirteen patients subsequently underwent operation. All but one of the arrhythmogenic areas found at surgical mapping had been identified at preoperative catheter mapping. Complications of the preoperative mapping procedure occurred in four patients, with complete resolution in three and minor long-term sequelae in the other. CONCLUSIONS: This technique permits detailed catheter mapping of all types of monomorphic ventricular tachycardias, including those leading to hemodynamic collapse, and should enable better choice and direction of surgical or catheter ablation.

Adult↗
PubMed1994

Suramin inhibits proliferation and DNA synthesis in transitional carcinoma cell lines.

Suramin is polysulfonated naphthylurea which has a broad range of antitumor activity. The mechanism of action of suramin is not completely understood, although it is known to inhibit enzymes in all cellular compartments, inhibit steroidogenesis and interfere with ligand-receptor binding. Suramin's large molecular size and negative charge should make it poorly absorbed through the bladder mucosa, a desired characteristic for an intravesical chemotherapeutic agent. We examined the ability of suramin to inhibit thymidine uptake and decrease cellular proliferation in 4 transitional cell carcinoma cell lines grown in vitro to determine if suramin might be a new candidate drug of treatment for patients with superficial bladder cancer. Suramin inhibited cellular proliferation of all cell lines tested (MBT2, T24, RT4 and TCCSUP) in a dose-dependent fashion. Fifty per cent inhibition of cellular proliferation compared with controls was seen with suramin concentrations of 250 to 400 micrograms/ml. by, at most, 5 to 9 days of exposure. The cell line RT4 was the cell line most sensitive to the growth inhibitory effect of suramin, with 50% growth inhibition compared with controls achieved after 3 days' exposure to a suramin concentration of 100 micrograms/ml. Suramin inhibited DNA synthesis in a dose-dependent fashion, as measured by thymidine uptake, in 3 of the 4 cell lines tested (MBT2, T24, and RT4). Suramin inhibited thymidine uptake by TCCSUP in a dose-dependent fashion, but did not achieve statistical significance.

Animals↗
PubMed1994

Vasopressin V1 and V2 receptors in diabetes mellitus.

Diabetes mellitus causes hypertonicity, increased plasma arginine vasopressin (AVP), polydipsia, and polyuria. Downregulation of AVP V2 receptors may contribute to the polyuria through diminished V2 receptor-mediated free water retention. After 2 wk of streptozotocin-induced diabetes mellitus, the diabetic rats had raised plasma glucose, AVP, and osmolality levels (P < 0.001) compared with nondiabetic controls (Sham). Insulin treatment (4 U long-acting insulin sc, daily) partially lowered these values (P < 0.01). There was a reduction in the number of renal and hepatic V1 receptors in the diabetic and diabetic+insulin animals compared with the sham animals (P < 0.05). The receptor affinity remained unchanged. In parallel, there was a reduction in maximum AVP-activated total inositol phosphate production in the liver and kidney of the diabetic and diabetic+insulin animals compared with the sham animals (P < 0.05). The density and affinity of renal V2 receptors and AVP-stimulated adenosine 3',5'-cyclic monophosphate production in the diabetic and diabetic+insulin animals were unchanged compared with the sham. These results demonstrate differential regulation of AVP receptors and suggest that downregulation of renal V2 receptors does not contribute to the polyuria of diabetes. In contrast, downregulation of V1 receptors might contribute to diminished V1 receptor-mediated biological responses to AVP seen in diabetes mellitus.

Animals↗
PubMed1993

Development of a device for measuring adherence of skin grafts to the wound surface.

Adherence of a biological graft to the wound surface is the most important factor influencing the ultimate success of graft viability. A machine has been developed to test the adherence of biological graft materials to a substrate such as a wound surface. The peeling mode, which yields reproducible quantitative measurements of adherence, is a standard method for testing adhesives. The device is designed to continuously measure the force required to peel the graft from the substrate at a constant rate. This force is a function of the energy of adhesion per unit area of adhered surface. This device has been used to measure the peeling force of (2 x 2 cm) skin grafts which are applied to full-thickness wounds on mice. Results of tests on adherence of autografts on mice show that the peeling force increases significantly with time over the first 9 days of healing. Thus, this device is useful in quantitative comparison of various skin grafting techniques and artificial grafts.

Adhesiveness↗
PubMed1993

Ophthalmic herpes zoster.

A current review of ophthalmic zoster is presented including its virology, immunology, epidemiology and pathogenesis. We give our findings in 1356 patients referred to the Zoster Clinic at Moorfields Eye Hospital, London. The treatment of the disease and its ocular complications is discussed.

Fluorescein Angiography↗
PubMed1993

Risk characterization, risk communication, and risk management. The role of the occupational and environmental medicine physician.

Physicians who are board-certified in occupational and environmental medicine often have formal training and experience in toxicology, epidemiology, and industrial hygiene, as well as clinical medicine, human physiology, and pathology, and are well suited to be team members in the various phases of risk assessment, communication, and management. Those with several years of experience in the clinical, as well as administrative practice of occupational and environmental medicine, are engaged in the practical application of risk characterization, risk communication, and risk management on an almost daily basis. We propose that the occupational and environmental medicine physician is in a unique position to bridge the communication gap between those professionals who provide various components of the risk assessment process and those who manage those risks in society.

Communication↗
PubMed1992

The effect of suramin on laboratory tests of coagulation.

The antitrypanosomal drug suramin, which has recently been under investigation as a cancer chemotherapeutic agent, has previously been found to induce heparin-like anticoagulants in treated patients. In the currently reported work suramin is shown to have an additional anticoagulant activity that is due to direct effects of the drug on procoagulant proteins. The studies were conducted with pooled normal plasma treated in vitro with suramin and with plasma samples obtained from patients who had received the drug intravenously for 2 weeks. It is demonstrated that in plasma suramin inhibits factors V, VIII, IX, X, XI, and XII, while thrombin, prothrombin, and factor VII are unaffected. The inhibition of factor V is virtually irreversible, although the effect of suramin on the other factors is readily reversed by dilution.

Blood Coagulation↗
PubMed1992

Degenerative disc disease in the lumbar spine: another cause for focally reduced activity on marrow scintigraphy.

A patient is presented in whom a focal reduction in marrow activity in the lumbar spine on both leucocyte and nanocolloid marrow scintigraphy was subsequently shown to be due to fatty infiltration of marrow in association with disc degeneration. Degenerative disease in the lumbar spine has not been previously described as a cause of abnormal bone marrow distribution by such means and needs to distinguished from a more serious pathology, such as malignant infiltration and vertebral infection, which it may mimic. In a retrospective review of 33 nanocolloid bone marrow and 117 leucocyte scintigrams, 8 showed a degree of reduced marrow activity in the lumbar spine consistent with that caused by degenerative changes.

Adult↗
PubMed1992

The Candida albicans PMM1 gene encoding phosphomannomutase complements a Saccharomyces cerevisiae sec 53-6 mutation.

We have constructed an ordered-array genomic DNA library of the pathogenic dimorphic fungus Candida albicans which facilitates the rapid cloning of C. albicans genes by hybridisation. Using the Saccharomyces cerevisiae SEC53 gene encoding phosphomannomutase as a hybridisation probe we have cloned the C. albicans homologue, PMM1, and determined its sequence. This gene shows high similarity, both at the nucleotide (76.2%) and amino-acid (77.7%) level, to the S. cerevisiae SEC53 gene. We have used the C. albicans PMM1 gene, in single copy, to transform temperature-sensitive S. cerevisiae sec53-6 mutant cells, which are defective in PMM activity at 37 degrees C, to growth at 37 degrees C. The C. albicans PMM1 gene is thus the structural and functional equivalent of the SEC53 gene.

Autoradiography↗
PubMed1992

Photodynamic therapy in the treatment of Bowen's disease.

BACKGROUND: The treatment of Bowen's disease in anatomically difficult areas or especially large lesions can challenge accepted modalities of treatment. OBJECTIVE: The purpose of this study was to illustrate the effectiveness of photodynamic therapy in the treatment of Bowen's disease. In addition, photodynamic therapy may be used as adjuvant therapy for difficult lesions. METHODS: Six patients with Bowen's disease in various anatomic sites were treated with photodynamic therapy. Four were in a difficult anatomic site, or were especially large, or both. Photofrin, 1.0 mg/kg, was administered intravenously and laser treatment was given approximately 48 hours later with the argon dye laser. Light was administered at a wavelength of 630 nm and the light dose ranged from 185 to 250 joules/cm2. Treatment was given by surface radiation only. RESULTS: Eight lesions were treated. All showed a complete response at 3 months (100%) and continue to show a complete response at 6 and 12 months. Morbidity was low; the most significant side effects were moderate pain and edema. Healing time varied depending on the size of the lesion. CONCLUSION: Photodynamic therapy is an effective and useful alternative for Bowen's disease, especially those lesions in anatomically difficult areas or those that are especially large.

Adult↗