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Biomedical subjects

M G Wickham

Publications and source records attributed to M G Wickham.

At least 19 recordsLinked to original sources
PubMed1988

Selected review on genetic factors in myopia.

This article reviews representative literature concerning pedigrees for myopia, heritability studies on refractive error and the ocular components, and other work relating to genetic factors in myopia development. Low myopia most likely reflects the influences of multiple genes. Some types of high myopia may have monogenic inheritance. Refractive error and the ocular refractive components have heritabilities intermediate between zero and one, as complied from several studies, indicating familial resemblance, but also non-genetic variation. It is likely that both heredity and environment have roles in determining refractive status. An understanding of their respective roles awaits the elucidation of the cellular and anatomical mechanisms of myopia development.

Humans↗
PubMed1983

Vitreous carbon: a new material for making microtome knives.

The quality of sections obtained by microtomy depends to a large extent on the quality and characteristics of the microtome knife itself. Despite the need for improved microtomy techniques, there have been few significant developments since the introduction of glass and diamond knives in the 1950's. The manufacture of microtome knives from vitreous carbon provides new possibilities for developing both improved methods and improved equipment for specimen sectioning. Vitreous carbon has unique physical properties that lend themselves to the generation of precision cutting edges. Such as edge can be obtained either by breaking a piece of vitreous carbon or by using lapidary techniques. The resultant edge seems well adapted to both thick and thin sectioning. The introduction of vitreous carbon as a sectioning tool offers a significant alternative to metal, glass and diamond knives.

Carbon↗
PubMed1980

Light element abundance in brain nuclei using energy dispersive x-ray analysis and atomic absorption spectrophotometry.

A comparative study of light element (congruent to ion) abundance in isolated brain nuclei, using atomic absorption (AA) spectrophotometry and the scanning electron microscope mode of energy dispersive x-ray analysis (EDXA), demonstrated similar statistical trends in the abundance of Na, Mg, and K at 0 time and at 4 min of total brain ischemia. The obtained correlation strengthens the validity of the comparison of quantitative and semi-quantitative procedures. The EDXA technique represents a new approach to the study of ionic shifts in brain ischemia that may prove useful in other areas of brain research as well.

Animals↗
PubMed1979

Immobilization of viral antigens on filter paper for a [125I]staphylococcal protein A immunoassay: a rapid and sensitive technique for detection of herpes simplex virus antigens and antiviral antibodies.

A new technique is described for the rapid detection and quantitation of herpes simplex virus (HSV) antigens and antiviral antibodies. It involves immobilization of HSV antigens on filter paper discs and subsequent analysis by 125I-labeled staphylococcal protein A (SPA) radioimmunoassay. A specially designed 96-well filtration device is employed which serves both as an incubation chamber and as a filtration manifold. It is rapid, simple, sensitive and specific, and requires only small volumes of antiserum and few target cells. The results may be readily and objectively quantitated. This technique permits the simultaneous assay of a large number of specimens in less than 1 h. Its sensitivity is considerably greater than that of other currently used immunologic techniques, and it is amenable to automation. These characteristics suggest that this [125I]SPA immunofiltration technique may be applicable to the rapid diagnosis of viral infections.

Antibodies, Viral↗
PubMed1979

Argon laser trabeculotomy:long-term follow-up.

A five-year follow-up of argon laser trabeculectomy in a group of 28 male patients with bilateral patients with bilateral primary open-angle glaucoma showed an overall mean pressure drop of 10.3 mm Hg in treated eyes. Twenty percent of the treated eyes had a pressure less than 20 mm Hg up to two years after treatment. No specific laser parameters were associated with pressure lowering. The pressure drop appears more patient dependent than treatment dependent. A randomized clinical trial is suggested.

Adult↗
PubMed1979

Antimicrobials and the corneal endothelium.

The effects of various intraocular antibiotics and preservatives on the rabbit corneal endothelium were evaluated using vital staining, light, scanning, and transmission electron microscopy after topical application of the drugs and up to 2 days following anterior chamber injection. Benzalkonium chloride consistently produced the most severe and probably irreversible damage. Some changes which persisted for 2 days were found with methicillin. Gentamicin produced a moderate amount of cellular edema which disappeared after 2 days. Minimal changes were produced by dexamethasone and amphotericin B. Although these results should not be directly interpolated to the human situation, the face that some of these agents did produce changes in the rabbit corneal endothelium, which is well known to be heartier than human endothelium, indicates that caution should be taken when one considers injecting antibiotics intraocularly.

Administration, Topical↗
PubMed1978

Silicon identification in prosthesis-associated fibrous capsules.

The use of correlated microscopic techniques, including the scanning electron microscopic modes of backscattered electron imaging and energy dispersive x-ray analysis, aid in defining the process of dispersion of silicon-containing material around silicone rubber (polydimethylsiloxane) prosthetic devices.

Breast↗
PubMed1978

M-K medium and postmortem cytologic damage.

Freshly enucleated rabbit eyes were refrigerated at +4 degrees C under standard eye bank conditions for 2, 6, 9, and 21 days. One group of corneas with a scleral rim were excised and placed in M-K medium, stored for 18, 24, or 48 hr at +4 degrees C; they were then removed, and endothelial cell viability was evaluated with nitroblue tetrazolium. The cells were examined by light microscopy and scanning and transmission electron microscopy. A second group of corneas were similarly obtained and then used as donor corneas from 6 mm transplants. Each recipient rabbit was evaluated daily by slit-lamp biomicroscopy and corneal pachometry. Fourteen days postoperatively, the rabbits were sacrificed, the eyes enucleated, and the excised corneas were evaluated in a fashion similar to those of group 1. M-K medium storage protected the morphology and functional integrity of the rabbit corneal endothelium up to 48 hr beyond moist chamber storage for 2, 6, and 9 days. However, M-K medium appeared to have no such effect on corneas that had been moist chamber--stored for 21 days. These results suggest that some human corneas with a prolonged time from death to moist chamber storage may be utilized for corneal transplantation after further storage in M-K medium.

Animals↗
PubMed1976

A randomized technique of constant-pressure infusion.

A population study of measured inflow values of eyes of a group of adult male rhesus monkeys was done with a randomized technique of constant-pressure infusion. Each eye was presented with a sequence of 18 4-minute runs, consisting of three infusion runs for each of six pressures, in which the order of appearance of a given pressure had been randomized. A statistical analysis of the results indicates that only the independent variables of infusion pressure, type of anesthetic, and position in the sequence of the 18 infusion runs had a significant effect upon measured inflow.

Animals↗
PubMed1976

Centrioles and cilia in the mesothelial cells of the pericanalicular region.

An evaluation of 70 trabecular meshwork biopsies obtained at the time of therapeutic surgery in glaucomatous and cataractous eyes revealed that the mesothelial cells in the iridocorneal angle had a marked abundance of cilia and centrioles. The distribution of cells showing cilia and/or centrioles is positively correlated with the apparent aqueous humor outflow pathway. The morphology and arrangement of the cilia-centriole complexes in the angle are highly variable and show many forms not previously reported in a single tissue. There were no obvious correlations between organelle abundance and the identifiable factors affecting the patients involved in this study.

Biopsy↗