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Biomedical subjects

S A Miller

Publications and source records attributed to S A Miller.

At least 127 records · Page 7Linked to original sources
PubMed1989

Cell proliferation in chick oral membrane lags behind that of adjacent epithelia at the time of rupture.

Radioautographic analysis showed that ectoderm and endoderm cells in chick oral membrane continued to label with tritiated thymidine through the period of rupture, but their frequency of labeling was significantly lower than those of adjacent epithelia. Frequency of labeling increased in adjacent ectoderm and endoderm, while oral membrane rates remained relatively low, suggesting that growth in the membrane lags relative to adjacent epithelia. Relatively greater proliferation in adjacent epithelia could generate tension and pull apart the thinned oral membrane. Differentials in rates of cell proliferation, when considered along with knowledge of cellular rearrangements following changes in basal lamina and matrical components, suggest that differential growth is an important force in rupture of the avian oral membrane.

Animals↗
PubMed1989

Prediction of fertility of bovine semen: Preliminary studies with the hamster egg penetration test.

The ability of liposome-treated fresh and frozen spermatozoa from two bulls to interact with zona-free hamster oocytes was examined to show whether the in vitro test results would correspond with in vivo fertility as indicated by the 60 to 90 d nonreturn to service rates which, using frozen semen, were 77 and 59%, respectively. The motility of spermatozoa in washed suspensions was also rated. Hamster test results were obtained using three ejaculates from each bull both as fresh and frozen semen. The results with frozen semen corresponded with fertility. The averages of three hamster tests for oocyte penetration rates and mean number of spermatozoa per penetrated oocyte comparing spermatozoa from the bull with the higher fertility with spermatozoa from the bull with the lower fertility were 91% and 2.7 versus 56% and 1.4, respectively. Spermatozoa washed from frozen semen from the bull with the higher fertility interacted with hamster oocytes at the higher rate even when sperm motility was rated the same for both bulls. By contrast, fresh spermatozoa from the lower fertility bull interacted with hamster oocytes at a higher rate than spermatozoa from the higher fertility bull in six tests, comparing six ejaculates of fresh semen from both bulls. Comparing the higher fertility bull with the lower fertility bull, the average of six tests for oocyte penetration rates and mean number of spermatozoa per penetrated oocyte were 60% and 1.6 versus 89% and 3.0, respectively. This suggests that this hamster test cannot be used with fresh semen to predict relative levels of fertility of frozen semen. Also, the subjective rating of sperm motility did not correspond with the in vitro oocyte penetrating ability of the spermatozoa.

Journal Article↗
PubMed1989

Problems associated with the establishment of maximum nutrient limits in infant formula.

Because each increase in personal security is accompanied by a small but measurable decrease in individual liberty, congress and the American people have been reluctant to provide to the regulatory agencies authority beyond that which they believe is the minimum necessary to avoid a crisis. For government to act in any area involving nutrient fortification of foods requires an acceptable database demonstrating a health hazard. The requirements of current law demand that new formulas be investigated by appropriate clinical studies but do not grant the FDA clear authority to establish maximum limits for nutrients in infant formulas. Except when an unquestionable hazard can be demonstrated, there are important barriers to governmental action in this area. Without a clearly defined, scientifically acceptable database, without consensus in the scientific and professional community, and without public support for action to be taken in this area, the establishment of maximum limits for many nutrients will be extremely difficult.

Female↗
PubMed1989

Saccharin.

Saccharin, a nonnutritive sweetener discovered in 1879, has been the subject of controversy concerning its effect on public health on several occasions during this century. Over this period, the substance has come to be regarded as a useful commodity in the dietary management of diabetes mellitus. We review the historical and scientific background on the subject and propose a new approach in making public-health decisions on unique foods that serve a special dietary purpose.

Animals↗
PubMed1988

Variables associated with ultraviolet transmittance measurements of intraocular lenses.

We measured the spectral transmittance of 12 intraocular lenses with a spectroradiometer system that uses an integrating sphere input. We evaluated both low- and high-power lenses and varied the input aperture size between 1, 3, and 5 mm. These variations caused a significant difference in the transmittance characteristics of the intraocular lenses. Most significantly, the transmittance of the low-power model was two to six times greater than that of the high-power model in the cutoff region. The larger aperture resulted in, at most, a factor of two difference in transmittance. This effect was observed in intraocular lenses labeled both ultraviolet-absorbing and nonultraviolet-absorbing.

Absorption↗
PubMed1988

Inhibition of sexual reflexes by lumbosacral injection of a GABAB agonist in the male rat.

The effects of gamma-aminobutyric acid (GABA) agonists on penile reflexes were investigated. An intrathecal injection of baclofen (0.2, 0.4, or 0.8 microgram), a GABAB receptor agonist, into the subarachnoid space of the lumbosacral spinal cord (L5-S1), resulted in a dose-related decrease in the number of animals responding in a penile reflex test. Doses of 0.2 and 0.4 microgram of baclofen decreased the number of erections; 0.4 microgram also increased the latency to the first glans erection. The highest dose of baclofen (0.8 microgram) completely inhibited penile responses in these tests. None of these doses, however, prevented rats from copulating to ejaculation. Antecedent ejaculation, which facilitated the onset of penile reflexes in saline controls, also blocked the inhibitory effects on penile responses by the lower doses (0.2 and 0.4 microgram) of baclofen, but was ineffective in animals treated with 0.8 microgram baclofen. In contrast to the inhibitory effects of baclofen in the lumbosacral cord, an intrathecal injection of baclofen (0.8 microgram) at thoracic segments (T8-T10) did not affect penile erections elicited following an ejaculation. The role of spinal GABAA receptors in sexual reflexes was assessed by intrathecal injection of a GABAA agonist. THIP (0.5.1. or 2 micrograms), onto the lumbosacral cord. Only at the largest dose of THIP were slight inhibitory effects on penile reflexes observed. Together, these data indicate that stimulation of GABAB receptors in the lumbosacral spinal cord inhibits erectile mechanisms ex copula.

Animals↗
PubMed1988

Changes in vascular and metabolic reactivity as indices of ischaemia in the penumbra.

The reactivities of cerebral cortical blood flow (hydrogen clearance) and of compensated NADH fluorescence to local cortical electrical stimulation were examined on the marginal gyrus before and after transorbital occlusion of the middle cerebral artery in cats. Prestimulus cerebral blood flow (CBF) was 38.2 +/- 12.9 (SD) ml 100 g-1 min-1 and fell to 19.8 +/- 11.1 following occlusion (p less than 0.02). Peak hydrogen clearance rate (percent increase above prestimulus clearance) was 81.6 +/- 53.6 and fell to 19.9 +/- 29.8 after middle cerebral artery occlusion (p less than 0.01). Steady-state NADH fluorescence rose from 33.5 +/- 10.7 to 40.5 +/- 17.6% full-scale deflection following MCAO (p less than 0.01). Latency from stimulus to maximal fluorescence depression in response to cortical stimulation increased from 12.2 +/- 8.2 to 22.1 +/- 11.9 s (p less than 0.01). Hyperaemic responses at anteromedial sites on the marginal gyrus significantly exceeded those at posterolateral sites. The results are interpreted as indicating early ischaemic metabolic change; however, the presence of residual vasodilator responses to stimulation suggests that flow reduction and early ischaemic change in the territory studied are not simply due to inadequate collateral input, but may also reflect deafferentation or functional suppression. The possible significance of diminished vascular reactivity in the penumbra as a cause of increased vulnerability to extracellular release of excitatory amino acids is discussed.

Animals↗
PubMed1988

Chemiluminescence immunoassay for progesterone in plasma incorporating acridinium ester labelled antigen.

A sensitive, solid-phase chemiluminescence immunoassay suitable for determining progesterone concentrations in plasma has been developed. The solid-phase antiserum was prepared by coupling a monoclonal progesterone-antibody, raised against a progesterone-11 alpha-hemisuccinyl/bovine serum albumin conjugate, to cyanogen bromide activated cellulose. An 11 alpha-progesteryl-2-carboxymethyltyramine-4-(10-methyl)-a cri dinium-9-carboxylate conjugate was used as the chemiluminescent label. The assay had a lower limit of sensitivity of 3 pg/assay tube and satisfied accepted validation criteria. Progesterone concentrations determined by chemiluminescence assay were in good agreement not only with a radioimmunoassay in routine use but also with a gas chromatography-mass spectrometry procedure.

Acridines↗
PubMed1987

Sudden infant death in service families.

A study of all the cot deaths in infancy which occurred in Service families in British Forces Germany (BFG) from 1981-4 was undertaken in order to ascertain the frequency of these tragedies. The total number of deaths was ninety-seven and in sixty cases no cause of death was found at post mortem. The incidence in the Service community was calculated so that comparison could be made with the civilian population of England and Wales. The results of the study indicated that cot deaths occurred relatively more frequently in the Service population even allowing for socio-economic differences between the two groups. However, postneonatal deaths from causes other than cot death occurred less often in BFG. Cot deaths are therefore the cause of the higher postneonatal mortality rates in the Service community and they constitute an important target for preventive medicine. The measures which have been taken in BFG in recent years to reduce the number of cot deaths are discussed in this paper together with some further ideas which might help to solve this distressing problem.

Adult↗
PubMed1987

Comparison of acid phosphatase ACP1 variants by isoelectric focusing and conventional electrophoresis: identification of three new alleles, ACP1*N, ACP1*P and ACP1*S.

Three new alleles of human red cell acid phosphatase (ACP1) have been identified by comparison with previously reported variants using three different electrophoretic techniques. Family data are available on all the variants and show genetic transmission of the rare alleles ACP1*N, ACP1*P and ACP1*S. Further evidence of a rare allele demonstrating reversed 'A' activity is also described. The report documents the need to use several electrophoretic techniques to characterize new or rare variants.

Acid Phosphatase↗
PubMed1987

The 1990 National Nutrition Objectives: lessons for the future.

The 1990 objectives are a first attempt to establish quantified goals in public health nutrition. Lessons from this experience can benefit future efforts. Apparent problems related, for example, to data, methodology, feasibility, and clarity have hindered the implementation and monitoring of progress on several goals. A major step toward improvement is the development of standard criteria for evaluating proposed objectives. Dietitians and nutritionists have a special interest and responsibility in developing the National Nutrition Objectives for the Year 2000. They also have special opportunities for integrating current and future nutrition objectives into programs at the state and local levels.

Health Promotion↗
PubMed1986

The effects of etomidate in the cat middle cerebral artery occlusion model of brain ischaemia. An experimental study.

The effects of etomidate on focal cerebral ischaemia following transorbital occlusion of the cat middle cerebral artery were investigated. Etomidate had no effect on CBF before or after onset of ischaemia by comparison with controls, but caused a greater fall in CBF in cats with high preocclusion or initial ischaemic CBF than in those in which CBF was lower. There were more sustained rises in Kp on SG. The established flow threshold for water accumulation was lost; more gyri with CBF above and fewer gyri with CBF below the flow threshold accumulated water. The relationship between mean occlusion CBF and in vitro GABA uptake was lost; uptakes from MG were lower and from SG and EG higher than expected. In the ischaemic penumbra there was a trend towards reduction in CBF, disruption of ion homeostasis and cerebral oedema formation, whilst in areas of lower flow there was some recovery of GABA uptake and less cerebral oedema following administration of etomidate.

Animals↗