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Biomedical subjects

M Silver

Publications and source records attributed to M Silver.

At least 145 records · Page 8Linked to original sources
PubMed1987

Sympathoadrenal and other responses to hypoglycaemia in the young foal.

The effects of insulin-induced hypoglycaemia on plasma catecholamines, cortisol and metabolites have been examined in newborn and 7-14-day-old foals. The fall in plasma glucose elicited by the highest dose of insulin (1.0 i.u./kg) given to the neonates was slower in onset and less severe in effect than 0.5 i.u./kg in the older foals. There was a significant inverse correlation between the concentrations of glucose and adrenaline (but not noradrenaline) in plasma once the glucose level had fallen below 2 mmol/l; the adrenergic response to hypoglycaemia was greater in the 7-14-day-old foals than in the neonates. No significant changes in glucose or catecholamines were seen after fasting alone. The adrenocortical response to hypoglycaemia was poor after birth, but significant changes occurred in the older foals with a 3-fold increase in plasma cortisol at 60 min after 0.5 i.u. insulin/kg. There were significant increases in plasma FFA after hypoglycaemia in both groups of animals, but the rise was less pronounced in the neonates. A significant positive correlation was found between plasma adrenaline and FFA values. Hypoglycaemia also resulted in a significant rise in plasma lactate and a slow fall in alpha-amino nitrogen. These findings show that hypoglycaemia in the foal is followed by stimulation of the adrenal medullary component of the sympathetic system and by activation of the adrenal cortex with a number of consequent metabolic changes. The hypoglycaemic effects of insulin were more intense and the response more rapid in the older foals than in the neonates, which exhibited some degree of insulin resistance.

Animals↗
PubMed1987

Using restraint.

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Aged↗
PubMed1986

Congenital anomalies in American Indians of British Columbia.

Birth prevalences of congenital anomalies in the American Indians of British Columbia are compared with those of the total British Columbia population. This study is based on data from the British Columbia Health Surveillance Registry for a 16-year period (1966-1981) judged to be the most reliable reporting period in the 35-year history of the registry. The overall congenital anomaly frequency is lower in Indians than in the general population (45 versus 60 per 1,000 livebirths). The Indian rates for individual anomalies are lower than the corresponding general population rates with the exception of orofacial clefting and congenital heart defects. Defects of the central nervous system in both populations are comparable. There is a striking paucity of hypospadias, other anomalies of the genital organs and foot deformities in Indian males. It is suggested that the differences in the congenital anomaly rates between the American Indians and the non-Indians of British Columbia may reflect genetic differences between the two groups, but differences in ascertainment and infant mortality probably also play a role.

British Columbia↗
PubMed1986

Study of arterial blood pressure in newborn foals using an electronic sphygmomanometer.

An electronic sphygmomanometer which functions on oscillometric principles, was used to measure arterial blood pressure in foals. Its accuracy was assessed by comparison with results obtained by direct measurement in anaesthetised pony foals, aged 34 to 64 days. Correlations between data obtained by the two methods were highly significant but the sphygmomanometric readings were consistently lower than those obtained by direct measurement. An equation was derived from the pooled values for mean, systolic and diastolic pressure measurements. This was used as a correction factor when the oscillometric method was employed in the field on Thoroughbred foals, during the first three days post partum, and on pony foals during the first day only. There were no significant differences between systolic, diastolic and mean values in Thoroughbreds on Days 1, 2 or 3 after birth. Measurements recorded on the first day after foaling were significantly lower (P less than 0.025) in ponies than in Thoroughbreds. Blood pressure measurements in Thoroughbreds and ponies were substantially higher than those reported previously using the ultrasonic Doppler technique.

Animals↗
PubMed1986

The effect of pancreatectomy on the uptake of metabolites by the sheep fetus.

The effects of fetal pancreatectomy on the uptake of oxygen, glucose and lactate by the fetus, uterus and uteroplacental tissues were investigated in chronically catheterized sheep during the last third of gestation. Pancreatectomy reduced the uptake of glucose by the fetus but had little apparent effect on glucose uptake by the uterus or uteroplacental tissues. The mean umbilical uptake of glucose by the pancreatectomized fetuses was 10.4 +/- 1.1 mumol/kg . min (n = 4) which was significantly less than the value observed in the intact fetuses (24.5 +/- 2.7 mumol/kg . min, n = 4, P less than 0.01). When all the data from the pancreatectomized and intact fetuses were combined, there was a significant positive correlation between the plasma insulin concentration in utero and the umbilical uptake of glucose (r = 0.95, n = 14, P less than 0.01). The glucose/oxygen quotient in the pancreatectomized fetuses (0.32 +/- 0.02, n = 9) was significantly less than the value observed in the intact fetuses (0.59 +/- 0.04, n = 6, P less than 0.01). There was also a significant positive correlation between the glucose/oxygen quotient and the plasma concentration of insulin in the fetus (r = 0.73, n = 59, P less than 0.01). Pancreatectomy had no significant effect on the fetal lactate/oxygen quotient or on the uptake of oxygen or lactate by any of the tissues. These observations demonstrate that the endogenous concentration of insulin is a physiological regulator of glucose uptake by the fetal tissues.

Animals↗
PubMed1986

The role of ingestion in the development of the small intestine in fetal sheep.

We have examined the influence of preventing the passage of swallowed fluid on the development of the small intestine during late gestation in fetal sheep. In four fetuses at 90 d of gestation, the oesophagus was ligated and fistulated, causing swallowed fluid to enter the amniotic sac. Tissue was removed from proximal and distal parts of the small intestine for histological analysis at 136 d (term is 147 d). The body weights of the four experimental fetuses were not significantly different from those of fourteen age- and breed-matched fetuses which were used as controls. However, the width of the mucosal layers at both sites in the small intestine was reduced by approximately 25% in the fistulated fetuses. This was largely attributable to a reduction in villus height of approximately 30%. The densities of villi and crypts increased significantly at the proximal and distal sites respectively. These findings indicate that the ingestion of fluid during late gestation plays a role in promoting growth of the mucosal elements of the small intestine. The way in which this occurs is not clear although it may be mediated either by trophic factors present in either amniotic or pulmonary fluid, or by the release of gastrointestinal hormones, such as gastrin, as a result of gut distension.

Animals↗
PubMed1986

Enterocyte migration in the foetal sheep small intestine.

The migration of enterocytes was studied in the small intestine of foetal sheep at 115 and 136 days of gestation in utero. The speed of migration in all cases was slower than that reported in the adult. At 115 days, the migration rate was 4.88 and 4.96 percent villus height/day for the proximal and distal small intestine, respectively. At 136 days, the migration rate was significantly increased (p less than 0.05) to 12.0 for the proximal and to 8.5%, for the distal small intestine. Rates of villus length increase were between 0.007 and 0.012 mm/day over the time course studied. The migration rates, expressed as millimeters per day, were between 0.23 and 0.76 mm/day, hence the rate of migration was much greater (between 3 and 16 times) than the villus growth rate.

Animals↗
PubMed1986

Pancreatic alpha cell function in the fetal and newborn pig.

Plasma glucagon concentrations were measured in chronically catheterized fetal pigs during the last third of gestation and compared with the values observed in anaesthetized fetuses of similar gestational age. The mean plasma concentration of glucagon in the chronically catheterized fetuses was 10.0 +/- 1.4 (S.E.M.) pmol/l (n = 11; term = 114 +/- 2 days). Concentrations were increased after catheterization and fell to baseline values within 48 h of surgery. Arginine infusion evoked a rapid release of glucagon in chronically catheterized fetuses between 105 and 108 days of gestation; the mean maximum increment in plasma glucagon was 15.4 +/- 4.5 pmol/l (n = 5). Plasma glucagon concentrations increased with increasing gestational age in both anaesthetized and chronically catheterized fetuses. Between 95 and 110 days of gestation, glucagon levels were significantly higher in anaesthetized fetuses than in chronically catheterized animals with similar normal pH values. Catheterization and prematurity had no apparent effect on plasma glucagon levels at birth. The plasma concentrations at birth were similar to those observed in the chronically catheterized fetuses in utero provided the piglets did not become acidotic during delivery. Significantly higher plasma levels of glucagon were found in newborn piglets with acidaemia (pH less than 7.3) than in piglets with normal pH values at birth (pH greater than 7.3). When all the data from the newborn piglets were combined, there was a significant negative correlation (r = -0.79, n = 39, P less than 0.01) between blood pH and the plasma concentration of glucagon at birth. These observations demonstrate that the fetal alpha cells are functional and responsive in utero and at birth.

Animals↗
PubMed1986

Control of lens cell differentiation and ion fluxes by growth factors.

The results of these studies suggest that an insulin-like growth factor, lentropin, present in the vitreous humor of the eye, is responsible for stimulating lens epithelial cells to differentiate into lens fiber cells during normal lens growth. Lentropin has been shown to stimulate embryonic lens epithelial cells to elongate, specialize for the synthesis of delta crystallin, the major protein synthesized in chicken embryo fiber cells, and to cease DNA synthesis and mitosis. Lentropin appears to decrease the permeability of the plasma membrane to potassium and, by this mechanism, may cause lens fiber cell elongation.

Animals↗
PubMed1985

Rubella: immunity and vaccination in schoolgirls.

Of 191 schoolgirls, 128 volunteered to take part in a feasibility study of serotesting before and after rubella vaccination, and all responded to RA 27/3 vaccine. Had the serum samples been taken by a fingerprick method the number of volunteers would probably have increased considerably. A change in policy for rubella vaccination to testing both before and after vaccination would cost no more than the existing policy, would ensure primary response, and would differentiate those women who were protected by the vaccine from those with antibody to wild virus.

Adolescent↗
PubMed1985

The effects of cortisol on the concentration of glycogen in different tissues in the chronically catheterized fetal pig.

The effect of exogenous cortisol on glycogen deposition in a number of fetal tissues was investigated in chronically catheterized fetal pigs between 80 and 95 d of gestation (term 114 d). Intravascular infusion of cortisol for 48 h increased the fetal plasma concentration of cortisol 4-fold to a value similar to that observed in piglets near to term. After infusion of cortisol, the concentration of glycogen in the lung was lower while the levels in skeletal muscle and liver were higher than those found in unoperated fetuses. There were no detectable changes in either skin or cardiac muscle glycogen after cortisol infusion. High endogenous cortisol concentrations were observed in some of the catheterized control fetuses and in two unoperated fetuses adjacent to the site of cortisol infusion. These fetuses also had detectable changes in lung, liver and skeletal muscle glycogen. When the data from all the fetuses, whether infused, control catheterized or unoperated, were combined there was a significant positive correlation between both liver and skeletal muscle glycogen concentrations and log plasma cortisol (r = 0.70 and 0.72 respectively, P less than 0.01). Lung glycogen levels were inversely related to log plasma cortisol (r = -0.67, P less than 0.01). No relation between either cardiac or skin glycogen concentration and fetal plasma cortisol could be detected. These observations demonstrate that cortisol has a marked effect on tissue glycogen levels in the immature fetal pig and suggest that the changes in glycogen concentrations observed in the liver, lung and skeletal muscle before term may be due to the pre-partum surge in fetal cortisol.

Animals↗
PubMed1985

Parameters for the operation of bacterial thiosalt oxidation ponds.

Shake flask and pH-controlled reactor tests were used to determine the mathematical parameters for a mixed-culture bacterial thiosalt treatment pond. Values determined were as follows: K(m) and V(max) (thiosulfate), 9.83 g/liter and 243.9 mg/liter per h, respectively; K(i) (lead), 3.17 mg/liter; K(i) (copper), 1.27 mg/liter; Q(10) between 10 and 30 degrees C, 1.95. From these parameters, the required bioxidation pond volume and residence time could be calculated. Soluble zinc (0.2 g/liter) and particulate mill products and by-products (0.25 g/liter) were not inhibitory. Correlation with an operating thiosalt biooxidation pond showed the parameters used to be valid for thiosalt concentrations up to at least 2 g/liter, lead concentrations of at least 10 mg/liter, and temperatures of >2 degrees C.

Journal Article↗
PubMed1985

Endothelial regeneration. VII. Lack of intimal proliferation after defined injury to rat aorta.

Rat aortas were denuded of endothelium by the use of catheters, which removed either a zone 10-15 cells wide or a zone 90-120 cells wide. Each animal received 3H-thymidine at 1, 16, and 24 hours before death, and groups of 3 animals were killed at 2, 3, 4, and 7 days after the small injury or 4, 5, 7, 14, and 42 days after the large injury. Scanning electron microscopy showed that the smaller injury was rehealed with endothelium by approximately 72 hours, and the large injury was repopulated by endothelium after 7-8 days. In aortas subjected to the 10-15-cell-wide injury, no intimal thickening nor intimal smooth-muscle proliferation was observed. After the larger injury, no obvious intimal thickening was present, although a few intimal cells were observed at sites where the internal elastic lamella was discontinuous. No significant increase in smooth-muscle-cell replication was detected in these aortas at any time after injury.

Animals↗
PubMed1984

Assessment of efficacy of intervention in hearing impaired children with speech and language deficits.

The diagnosis of hearing loss in children with speech and language deficits by the otorhinolaryngologist involves a large allocation of sources. The ability to assess the efficacy of intervention in order to minimize speech and language deficits is an aspect in the care of these children which has not been generally considered as part of the child's ongoing medical care. These children have speech and language deficits predominantly from hearing impairment and occasionally from a primary language disorder. The effect of intervention (usually a hearing aid), the special education program for the hearing impaired child, and the language therapy for the child with a primary language disorder are seldom measured. The ability to assess and monitor the child's progress is essential for the care of these patients. The continual monitoring of the child's progress is accomplished by periodic assessment of the child's speech and language. An instrument to do this has been developed and used by the Department of Otorhinolaryngectomy at the Albert Einstein College of Medicine for a number of years. The utilization of this instrument, as demonstrated by a series of case reports, will be presented. These will include children in which intervention was successful and those for whom it was unsuccessful, with an analysis of the reasons underlying the effectiveness for each child. It is recommended that every child with a speech and language deficit should be monitored periodically so that the child's progress, or lack of progress, can be determined. If the child is not progressing, additional remediation can be instituted to attempt to prevent a permanent speech and language deficiency.

Child↗