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Biomedical subjects

M F Clark

Publications and source records attributed to M F Clark.

At least 19 recordsLinked to original sources
PubMed2003

Chylous effusions complicating lymphoma: a serious event with octreotide as a treatment option.

Chylous effusions have an identical appearance to milk and occur when the thoracic duct is blocked. Since chyle represents direct absorption of fat from the small intestine lacteals, it is rich in fat, calories, vitamins and immunoglobulins. Drainage of this milk-like fluid from any cavity (chest or abdomen) results in rapid weight loss and profound cachexia. The recognition of this milk-like fluid as chyle is urgent for the implementation of the correct treatment. In adults, lymphoma is one of the commonest malignancies to cause blockages in the thoracic duct. Once the diagnosis is made, conservative treatment with strict dietary adjustment often fails to prevent weight loss or resolve the underlying cause. Since the condition is uncommon, no guidelines exist. Many surgeons recommend early surgical intervention before the patient becomes too weak. Surgery may also fail. We report the case of a 62-year-old man with chylous effusions and a weight loss of 30 kg. The nature of the effusion was unrecognized for the first 16 weeks. Upon diagnosis, dietary adjustment was made and a lymphangiogram organized with a view to surgery. Literature searches revealed two cases in which somatostatin was used after surgical procedures failed. We therefore used octreotide (a synthetic analogue of somatostatin). We report complete resolution of the condition within 72 h leading to the resumption of a normal diet and discharge within 2 weeks.

Cardiac Surgical Procedures↗
PubMed1993

An in vitro study into the effect of a bacterial artificial caries system on the enamel adjacent to composite and amalgam restorations.

A microbial artificial caries system was used to produce caries-like lesions adjacent to amalgam and composite restorations. Polarised microscopy allowed measurement of outer and wall lesions depths. Comparison was made of the depths found in relation to the restorative materials, margin finishing procedures (composite group), varnish application (amalgam group) and thermal stressing. It was found that differences were detectable between the different restorative materials and the type of margin finishing procedure used in the composite group. Varnish application and thermal stressing had little effect. Some comparison is made between this microbial technique, other artificial caries techniques, and other methods of assessing marginal leakage.

Adolescent↗
PubMed1991

Travel nursing.

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Contract Services↗
PubMed1988

Prevention and termination of pacemaker-mediated tachycardia in a new DDD pacing system (Siemens-Pacesetter model 2010T).

The clinical incidence of Pacemaker-Mediated Tachycardia (PMT) has been substantially reduced with the availability of wide range postventricular atrial refractory period (PVARP) programmability in most current technology DDD pacemakers. However, patients may still be at clinical risk for PMT if the PVARP must be reduced to allow higher atrial tracking capability or VA conduction (VAC) is not periodically assessed to ensure adequate PVARP selection. A new DDD pacer (Siemens-Pacesetter Model 2010T) incorporates programmable responses to a sensed PVC to prevent PMT induction due to VAC following a PVC. In each of these responses, the PVARP is automatically extended to prevent detection of the retrograde P wave, thus preventing the PMT. Additionally, should a PMT occur for reasons other than a PVC, the selected PVARP extension algorithm is periodically invoked to terminate the PMT. This study was conducted to evaluate the operation and clinical benefit of these PVC response functions and PMT termination capabilities. The exact timing operation of the pacer during these responses is also reviewed.

Cardiac Complexes, Premature↗
PubMed1987

A method for the quantitative analysis of ELISA data.

A method is described for measuring relationships among virus serotypes. An indirect ELISA was used to obtain antibody-response curves for homologous and heterologous combinations of virus and dilutions of antibody. Data from the proportional response region of each curve were converted to logarithmic values and subjected to a form of regression analysis to derive relative titres for the various combinations of virus and antibody. SDI values were then obtained by calculating the mean difference in relative titres between homologous and reciprocal heterologous combinations. Virus models in two different groups were examined using this technique. Relative titres obtained were consistent and reproducible over several experiments indicating that the technique was capable of reliably discriminating among serotypes which differed by as little as 0.2 SDI.

Enzyme-Linked Immunosorbent Assay↗
PubMed1986

Characteristics and clinical effects of myopotential signals in a unipolar DDD pacemaker population.

Myopotential signals were recorded from atrial and ventricular leads during isometric exercise in 25 patients who had chronically implanted dual chamber pacemakers using the electrogram telemetry capability of the pacemakers. Average electrogram amplitude on the atrial channel was 0.92 mV (range 0.3 to 1.9) and on the ventricular channel was 0.98 mV (range 0.3 to 2.2); the difference was not significant. There was a strong correlation (R = 0.82) between the amplitude of myopotentials on the atrial and ventricular leads for individual patients. Myopotential sensing caused ventricular output inhibition in two patients (8%) and ventricular tracking in sixteen patients (64%). Pacemaker reprogramming abolished ventricular myopotential inhibition in all patients and stopped ventricular myopotential tracking in seven patients. We conclude that myopotentials can be analyzed and their effects ameliorated by a multiprogrammable pacemaker with electrogram telemetry capability.

Adult↗
PubMed1982

A simple indirect ELISA using F(ab')2 fragments of immunoglobulin.

An indirect ELISA is described in which (i) virus is trapped by F(ab')2 fragments of specific IgG immobilized on a solid phase support, (ii) trapped virus is detected by intact IgG (from the same or a different antiserum) and (iii) positive reactions are identified using an enzyme conjugate specific for the Fc portion of IgG. Pepsin digestion of the Fc portion of the trapping antibody permits the use of a general purpose enzyme conjugate to discriminate between trapping and detecting antibody. Consequently, the assay requires only a single virus-specific antiserum which is often all that is available to the plant virologist. The assay was at least as sensitive for detecting small amounts of antigen as the standard double-antibody sandwich procedure and, for some viruses, two- to fourfold more sensitive. The improvement in performance resulted largely from lower and more consistent background reactions. Both assays were equally effective in revealing heterologous reactions when optimized for detecting homologous antigen. However, increased cross-reactions were obtained in the F(ab')2 procedure by the use of higher concentrations of detecting antibody. The assay is considered particularly suited for comparing antisera from different sources or of different bleeds from the same source, and for investigations involving so few tests that the effort or expense of preparing individual virus-specific conjugates is not justified.

Antibodies, Viral↗
PubMed1977

Characteristics of the microplate method of enzyme-linked immunosorbent assay for the detection of plant viruses.

Some characteristics of a microplate method for the detection and assay of plant viruses using enzyme-labelled antibodies are described. The method enabled the highly sensitive detection of a number of morphologically different viruses in purified preparations and in unclarified extracts of herbaceous hosts and of infected crop plants. Virus concentrations were estimated by photometric measurement of the colour intensity of the hydrolysed substrate. The suitability of the tehcnique for various field and research applications is considered.

Enzyme-Linked Immunosorbent Assay↗
PubMed1976

The detection of viruses by enzyme-linked immunosorbent assay (ELISA).

The use of enzyme-linked antibodies for the detection of two morphologically different plant viruses is described. The technique is extremely sensitive, enabling assay of the viruses at concentrations as low as 10 to 100 ng/ml both in purified preparations and in crude plant extracts.

Alkaline Phosphatase↗