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Biomedical subjects

A Gordon

Publications and source records attributed to A Gordon.

At least 217 records · Page 12Linked to original sources
PubMed1985

Serum reduces the TSH content in rat pituitary cells in culture.

Euthyroid rat pituitary cells were plated on a natural extracellular matrix (ECM) and cultured in either a medium supplemented with hormones and growth factors (SM) or in an unsupplemented medium (USM). Hormone supplementation resulted in a marked increase in the number of cells and in a less pronounced increase in the TSH content. Addition of 10% dehormonized serum (DHS) to the medium caused a further increase in the cell number as well as a significant elevation in the GH content but, surprisingly, it caused also a dramatic decrease in the TSH content. Time course experiments revealed that the serum doubled the rate of suppression of the TSH. DHS prepared from rat serum was as effective as that prepared from foetal calf serum and heat-inactivation of the serum did not change its suppressive effect on the production of TSH. This effect was confined to the serum fraction which was precipitable with 45% ammonium sulphate but did not bind to Con-A. It is suggested that a high molecular weight protein fraction of serum reduces the number of thyrotrophs in the culture and/or decreases the rate of TSH production by these cells.

Animals↗
PubMed1985

Corneal infiltrates and extended-wear contact lenses.

Corneal infiltrates are a relatively rare but potentially serious complication of extended-wear contact lenses. Clinical experience with a large population of extended-wear patients suggested that these infiltrates have a characteristic location and appearance which may aid in diagnosis and management. The records of 51 patients (54 eyes) with extended-wear contact lenses and corneal infiltrates were reviewed. Nearly all the infiltrates were in the peripheral cornea and 67% were located superiorly, beneath the upper lid. No permanent visual loss resulted and all patients resumed extended-wear of contact lenses following a period of appropriate management. The clinical features, management, and possible etiologies are discussed. The sample reported herein is the largest, to date, of any reported in the ophthalmic literature.

Adolescent↗
PubMed1985

Refitting long-term asymptomatic PMMA lens wearers into gas permeable lenses.

Controversy exists as to whether patients who are asymptomatic, long term PMMA contact lens wearers demonstrating an acceptable clinical ocular response should be routinely refit into hard gas permeable lenses. Corneal thickness, corneal curvature, and refractive changes were measured on eight such patients when their lenses were changed to a gas permeable lens material (Boston II) while all other lens parameters were held constant. Corneal thickness decreased dramatically, corneal curvature flattened slightly, and refractive findings showed no significant changes. A simple reorder of the current lens design in the gas permeable material has been recommended as a reasonable "refitting" method for this type of patient.

Adolescent↗
PubMed1985

Value of umbilical blood acid-base studies in fetal assessment.

Determining umbilical vessel blood gas and acid-base values at delivery is a useful, noninvasive means of assessing the condition of the fetus and of reconstructing intrapartum events. These measurements provide a means of auditing the incidence and severity of fetal acidemia and of evaluating the efficacy of clinical measures of detection and treatment. In addition, these parameters may be useful in differentiating the various causes of fetal acidemia.

Acid-Base Equilibrium↗
PubMed1984

RK bacterial test for independently measuring chemical toxicity and mutagenicity: short-term forward selection assay.

A short-term bacterial assay system for determining the mutagenic potential of environmental substances was developed and validated. Genotoxic activity was demonstrated for selected substances from 10 categories of chemical agents. The RK test results were obtained with one Escherichia coli assay strain that was transiently exposed to, and then removed from the test substance prior to the selection step for mutant cells. The RK test employs a hitherto unused short-term assay technique for selecting forward mutations in the wild-type selector strain cells. The cells of the selector strain are killed upon shifting to 42 degrees C as a consequence of thermal derepression and subsequent expression of the replication genes from an integrated 10-kilobase fragment of phage lambda. Cells that acquire mutations in the responsible killing genes are detected by their colony-forming ability at 42 degrees C. A substance is determined to be genotoxic if it is capable of increasing the forward mutation frequency for appearance of these mutant cells. Toxicity of the agent is independently evaluated by examining its effect on the viability of the selector strain at 30 degrees C, when the viral replication genes remain repressed. The flexible assay protocol enables determination of the effect of pH on mutagenic activity, the requirement for metabolic activation, and assays of nearly insoluble or highly toxic substances.

Biotransformation↗
PubMed1984

Sex hormone binding globulin (SHBG) in breast cancer: a correlation with obesity but not with estrogen receptor status.

Plasma sex hormone binding globulin (SHBG) levels were determined in a group of 82 patients suffering from breast carcinoma with a known estrogen receptor status (ER). Overweight (greater than 20% of ideal weight) premenopausal patients had a significantly lower SHBG plasma level than their non-obese counterparts (43 pmol/ml vs 72.7 pmol/ml, P less than 0.001). No difference in plasma levels of SHBG was found between obese and non-obese postmenopausal patients. No correlation was found between SHBG levels and ER status either in non-obese premenopausal patients or in postmenopausal patients in general. Breast carcinoma patients had significantly higher SHBG plasma levels than a group of normal controls (57.9 pmol/ml vs 40.6 pmol/ml, P less than 0.01), but the stage of the disease did not influence the SHBG level within the breast carcinoma patients. Results of this study do not support a correlation between SHBG levels and ER status. SHBG plasma levels are significantly influenced by a patient's weight, particularly in those who are premenopausal.

Adult↗
PubMed1984

New method for the estimation of lean body mass in infants (EMME instrument): validation in nonhuman models.

An innovative, safe, and rapid method suitable for the determination of lean body mass in infants is described. The machine (EMME) operates on the principle that a biologic specimen in an electromagnetic field perturbs the field proportional to its conductivity which is dependent on the amount of electrolyte present. The physical characteristics of the EMME signal are described. Experiments done with phantom infants composed of electrolyte solution and corn oil showed a very linear relationship between fat-free volume and the natural log of the EMME signal (r = 0.97). A similar relationship was noted for ground beef (r = 0.91) and live rabbits (r = 0.99). The EMME instrument appears to hold promise as a rapid noninvasive means of determining lean body mass in infants.

Adipose Tissue↗
PubMed1984

A note on 'plotless' methods for estimating bacterial cell densities.

' Plotless ' techniques for determining population densities have been developed for, and applied to, higher plant populations. They can often be carried out more rapidly than techniques involving total counts of individuals in plots, or quadrants, but such plotless techniques have not been generally applied to the estimation of densities of bacterial cells. Direct microscopical counting of cell numbers in a field of view, an example of a plot-related method, has been traditionally used for microbial cell counts. In this study 'plot' and ' plotless ' methods on a variety of bacterial samples are compared. Estimates of bacterial cell density were obtained by measuring the distance of cells from a fixed point in a field of view. The values, which were more rapidly obtained, were directly correlated with total cell counts. Although there was some apparent deviation from a perfect 1:1 relationship with total counts, as indicated by a correlation coefficient less than 1.0, there were no significant differences between the replicated counts of bacteria on samples of tissue from the surface of Hypholoma basidiocarps (P less than 0.05). This indicated that the methods of enumeration were comparable. The distance-related estimates could readily be obtained from fields of view with cell densities varying over several orders of magnitude. It was more rapidly applied, particularly at high density, and the method was applicable not only to random cell distributions but also to the non-random distributions encountered when microbial cells aggregated into microcolonies. The method appears to be particularly well-suited for automated, digitized, direct counting procedures, as well as to estimating bacterial numbers on membrane filters and natural substrates.

Bacteria↗
PubMed1984

Ethanol and the gamma-aminobutyric acid-benzodiazepine receptor complex.

Ethanol appears to enhance gamma-aminobutyric acid (GABA)-mediated synaptic transmission. Using radioligand binding techniques, we investigated the possibility that the GABA-benzodiazepine receptor complex is the site responsible for this effect. Ethanol at concentrations up to 100 mM failed to alter binding of [3H]flunitrazepam (FNZ), [3H]Ro 15-1788, or [3H]methyl-beta-carboline-3-carboxylate (MBCC) to benzodiazepine receptors, or of [3H]muscimol to GABA receptors in rat brain membranes. Scatchard analyses of the binding of these radioligands at 4 degrees C and 37 degrees C revealed no significant effects of 100 mM ethanol on receptor affinity or number. A variety of drugs as well as chloride ion increased binding of [3H]FNZ and/or [3H]muscimol, but these influences were not modified by ethanol. These findings indicate that ethanol probably potentiates GABAergic neurotransmission at a signal transduction site beyond the GABA-benzodiazepine receptor complex.

Animals↗
PubMed1984

Evaluation of a home based health record booklet.

Despite the widespread use of home based child health records of varying complexity in England, there is a notable absence of their evaluation. Such a record booklet developed in the West Lambeth Health Authority has been used by parents, doctors, and community nurses to build up an independent chronological record of a child's birth statistics, health, growth, immunisation, development checks, and contacts with health services. A randomised controlled evaluation of the record, analyses of entries in it, and a survey of the views of mothers and health professionals using the record have been carried out. The need for such a record was confirmed by those questioned and analyses of entries in the booklet helped to modify and improve it. The evaluation was unable to show, however, any effect of the record on immunisation and developmental assessment service uptake. Its value in improving communication between the numerous health and other care agencies was dependent on its proper use.

Body Weight↗
PubMed1984

The changing place of radiology in obstetrics.

In 1970 42% of antenatal patients had an X-ray examination (88.6% involving abdominal exposure) but with the introduction of an ultrasound service in 1976 this figure had dropped to 3% by 1980. Looking at the indications for these it can be seen that X rays were still commonly performed for the detection of fetal abnormality and a further reduction in X-ray exposure of pregnant women could be achieved by using ultrasound in this situation. There was a dramatic decline in the use of erect lateral pelvimetry when the fetal presentation was known to be cephalic, especially when the head was engaged, reflecting an increasing awareness by obstetricians that this investigation is unrewarding in clinical practice.

Congenital Abnormalities↗