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Biomedical subjects

S Hughes

Publications and source records attributed to S Hughes.

At least 181 records · Page 10Linked to original sources
PubMed1991

Expression of superfast myosin in aneural regenerates of cat jaw muscle.

We investigated whether innervation is necessary for the expression of superfast myosin in regenerating cat jaw-closing muscle. Strips of jaw muscle were permitted to regenerate bilaterally in the beds of a fast limb muscle with innervation on one side being prevented surgically. Immunocytochemical analyses using anti-myosin heavy chain antibodies were done at various times postoperatively, the latest being after 78 days. We found little difference between innervated and uninnervated regenerates up to 27 days postoperatively. All regenerating myotubes expressed fetal myosin. In addition, some myotubes stained for superfast or slow myosin, while others stained for both superfast and slow myosins. Subsequently, uninnervated myotubes became atrophic but continued to express fetal, slow, and superfast myosins while innervated myofibers suppressed fetal and slow myosin expression. These results are consistent with the notion that satellite cells of jaw-closing muscles are committed to express superfast myosin during myogenesis, and that the expression of this program is independent of innervation.

Animals↗
PubMed1991

Basal lamina and superfast myosin expression in regenerating cat jaw muscle.

We investigated the possible role of extracellular matrix in specifying the expression of superfast myosin during cat jaw muscle regeneration. Equal proportions of muscle tissue from jaw and limb were minced together after killing cellular elements from one source. We allowed the mince to regenerate in the bed of a fast limb muscle. Regenerates were analyzed immunocytochemically at 71 to 294 days after operation. Fibers in control regenerates containing live cells from both sources expressed fast, superfast or slow myosins, or a mixture of these myosins. In regenerates containing only one type of live cells, we detected only myosins appropriate to the live cells. Our results suggest that during regeneration the original extracellular matrix of jaw-closing or limb muscle is unable to specify the expression of superfast or fast myosins, respectively; they point to the cellular elements, probably the satellite cells, as determinants of muscle specificity during regeneration.

Animals↗
PubMed1991

Abnormal responses to orthostatic testing in children and adolescents with recurrent unexplained syncope.

Syncope in the pediatric age group is a frequent event. Most often the cause is readily apparent--i.e., orthostatic hypotension or a vasovagal event. However, there are a large number of children with frequent recurrent unexplained syncope. Neither history, physical examination, nor standard testing reveals a cause. One hundred four consecutive patients were evaluated by orthostatic testing after standard methods found no cause for the recurrent syncope. Forty-seven (44%) of these 104 patients had syncope produced by orthostatic testing. Twenty-six of the 47 (55%) became syncopal within 5 minutes of testing initiation and 21 of the 47 (45%) after 5 to 11 minutes of testing. These patients had an average decrease of 81.5 mm Hg in blood pressure and a 25 beat/min decrease in heart rate. Of 12 control subjects, none lost consciousness with standing times as long as 14 minutes. Pacing was ineffective in preventing syncope, as two patients with a previously implanted normally functioning pacemaker had recurrent syncope clinically. Syncope was also induced by orthostatic testing, with the pacemaker showing a normal response with pacing as the patient became bradycardic. The syncopal event produced by orthostatic testing occurred with a downward blood pressure trend and a narrowing of the pulse pressure without a significant increase in heart rate. This was followed by a sudden drop in blood pressure and then by bradycardia. There is a group of children and adolescents with recurrent unexplained syncope due to abnormal orthostatic control mechanisms. Orthostatic testing appears helpful in identifying these patients.

Adolescent↗
PubMed1991

Control of cancer pain by epidural infusion of morphine.

Pain that cannot be controlled by traditional oral and parenteral methods in those patients with advanced cancer can be alleviated by spinal administration of narcotics. Epidural and intrathecal infusion with morphine causes analgesia by blocking spinal receptors without significant long-term central nervous, gastrointestinal, and genitourinary system effects. Of the total of 33 patients, epidural catheters inserted in 20 patients then connected by a subcutaneous tunnel to a continuous infusion system. Implanted pumps were used in each of these patients. Because of the cost and limitations of the implanted pumps, epidural catheters were connected, either directly or by subcutaneous reservoirs, to external ambulatory infusion pumps in the remaining 13 patients. Patient assessment by a linear analogue scale to measure pain levels determined that 23 of the 33 total patients (70%) had excellent or good relief of pain. The delivery of spinal administration of narcotics to treat intractable cancer pain in patients is safe. Most importantly, this method of delivery can be used in community hospitals, in outpatient settings, and in home health care programs.

Adult↗
PubMed1991

Heart rate perturbation in chick embryos: a comparison of two methods.

This report compares the effects of two methods of heart rate (HR) perturbation on stroke volume and dorsal aortic flow in the Hamburger-Hamilton stage 24 chick embryo. The sinus venosus was paced at intrinsic HR and at 150, 125, 75, and 50% of intrinsic HR (n = 23). Alternatively, a 1-mm steel probe heated to increase and cooled to decrease HR was applied to the sinus venosus (n = 15). All studies were performed in ovo at 37-38 degrees C. Aortic flow (mm3/S) and stroke volume (mm3/beat) were calculated from aortic velocity, aortic cross-sectional area, and HR. Atrioventricular (AV) inflow velocities were measured during pacing (n = 10) or probe application (n = 11) technique. Dorsal aortic flow was maximum at intrinsic HR and decreased at both increased and decreased HR. Stroke volume decreased proportionally to HR during rate increase. At decreased HR, when AV synchrony was disrupted (pacing), stroke volume was unchanged from intrinsic values. However, when AV synchrony was maintained at decreased HR (cold probe), the embryonic ventricle significantly increased stroke volume.

Animals↗
PubMed1991

Pulmonary embolism presenting as exercise-induced hypotension.

A 68-year-old man with remote history of previous myocardial infarction presented with a four-week history of intermittent dyspnea. After developing hypotension during an exercise tolerance test, he underwent cardiac catheterization, revealing significant pulmonary hypertension and two-vessel coronary artery disease. Pulmonary angiography confirmed the presence of pulmonary emboli which partially resolved after thrombolytic therapy. Subsequent treadmill testing confirmed the absence of exercise-induced hypotension two months following treatment. This case underscores the importance of considering pulmonary embolism as a potential cause of exercise-induced hypotension, since it can be successfully treated with thrombolytic agents weeks after the initial onset of symptoms.

Aged↗
PubMed1990

Opioid receptors in skeletal muscle of normal and dystrophic mice.

Autoradiography was used to investigate the presence of opioid receptors in soleus, extensor digitorum longus (EDL) and diaphragm muscles in two strains (C57BL/6J and C57BL/10) of mice which can inherit muscular dystrophy. Binding sites for two radiolabelled opioid ligands [125I]beta-endorphin and [3H]naloxone, were seen in a few muscle fibres in the normal mice. However, a significantly greater number of fibres exhibited the binding sites in the dystrophic individuals of both strains. The binding sites were not restricted to the endplate regions but were present over the entire surface in these fibres.

Animals↗
PubMed1990

Production and characterisation of monoclonal antibodies to parathyroid hormone-related protein.

The production and characterisation of 17 monoclonal antibodies to human parathyroid hormone-related protein (PTH-rP) 1-34 is described. Five of the antibodies were shown to be of high avidity (Ka 4 X 10(10)-1.9 X 10(11) L/M) and able to detect 15-100 pg PTH-rP 1-34 per tube by RIA. None cross-reacted with PTH 1-34, and inhibition studies with peptide subfragments of PTH-rP 1-34 indicated that all recognise a central region extending from residues 9-18 to between residues 23 and 34. All antibodies tested cross-reacted with native PTH-rP in culture fluids from keratinocytes and squamous cancer cell lines and in human and bovine milk. The concentrations of PTH-rP 1-34 (ng/ml) in these fluids as determined by RIA were: keratinocytes 1-3, squamous cancer 0.2-2.5, human milk, up to 80. Selected antibodies coupled to Sepharose 4B were used to extract PTH-rP from biological fluids with high yields.

Animals↗
PubMed1990

Regulation of beta-cell glucose transporter gene expression.

It has been postulated that a glucose transporter of beta cells (GLUT-2) may be important in glucose-stimulated insulin secretion. To determine whether this transporter is constitutively expressed or regulated, we subjected conscious unrestrained Wistar rats to perturbations in glucose homeostasis and quantitated beta-cell GLUT-2 mRNA by in situ hybridization. After 3 hr of hypoglycemia (glucose at 29 +/- 5 mg/dl), GLUT-2 and proinsulin mRNA signal densities were reduced by 25% of the level in control rats. After 4 days (blood glucose at 57 +/- 7 mg/dl vs. 120 +/- 10 mg/dl in saline-infused control rats), GLUT-2 and proinsulin mRNA densities were reduced by 85% and 65%, respectively (P = 0.001). After 12 days (glucose at 54 +/- 8 mg/dl), GLUT-2 mRNA signal density was undetectable whereas proinsulin mRNA was reduced by 51%. After 12 days of hypoglycemia, the Km for 3-O-methyl-D-glucose transport in isolated rat islets, normally 18-20 mM, was 2.5 mM. This provides functional evidence of a profound reduction of high Km glucose transporter in beta cells. In contrast, GLUT-2 was only slightly reduced by hypoglycemia in liver. To determine the effect of prolonged hyperglycemia, we also infused animals with 50% (wt/vol) glucose for 5 days (glucose at 200 +/- 50 mg/dl). Hyperglycemic clamping increased GLUT-2 mRNA by 46% (P = 0.001) whereas proinsulin mRNA doubled (P = 0.001). We conclude that GLUT-2 expression in beta cells, but not liver, is subject to regulation by certain perturbations in blood glucose homeostasis.

Animals↗
PubMed1990

The impact of community care on provision of informal care to homebound elderly persons.

This study examined the impact of community care on informal care provided by family and friends to homebound elderly persons. Secondary analyses were conducted on data collected from clients at baseline, 9 months (N = 225), and 48 months (N = 76) after acceptance to community care and home-delivered meals programs. Analyses revealed a significant increase in the amount of formal services provided to both groups of clients at 9 months and to community care clients at 48 months. The increase was attributed to the large proportion of "new" or "supplementary" services provided by agencies. No significant decrease in the amount of service provided by informal caregivers was found. In addition, regression analyses demonstrated only a weak impact of formal service on informal care. Analysis of patterns of service provision for each client demonstrated that formal care supplemented rather than substituted for informal care significantly more often in both the 9- and 48-month samples. We conclude that formal care in general supplemented the efforts of informal caregivers, and that informal caregiving remained stable over time.

Activities of Daily Living↗
PubMed1990

Use of buserelin in an IVF programme for pituitary-ovarian suppression prior to ovarian stimulation with exogenous gonadotrophins.

Daily s.c. injections of buserelin were commenced in the mid-luteal phase of the preceding cycle in 118 women undergoing in-vitro fertilization (IVF) and embryo transfer. Ovarian and pituitary suppression was said to have been adequately achieved when serum oestradiol was less than 50 pg/ml, serum LH less than 2.0 IU/l, no ovarian cysts greater than or equal to 10 mm diameter were present and menstruation had occurred. Nine groups of women were retrospectively identified after the administration of buserelin for 12 days according to whether pituitary and ovarian suppression had been achieved or not, and the reason for extended buserelin treatment prior to ovarian stimulation. Upon adequate suppression, patients were grouped in terms of the duration of exposure to buserelin, and ovarian stimulation was then started by daily injections of human menopausal gonadotrophin. There appeared to be no differences in the ovarian response for women down-regulated by day 12, 19 or greater than or equal to 26 days; those women requiring extended buserelin treatment did equally well compared to those women down-regulating quickly, in terms of number of oocytes recovered and fertilization rate. Clinical pregnancy rates per embryo transfer were 27/68(40%), 8/33(26%) and 4/17(24%) for those women down-regulated by days 12, 19 or greater than or equal to 26 respectively, and were not significantly different.

Adult↗
PubMed1990

Acylcarnitine is low in cord blood in cystic fibrosis.

Carnitine metabolites (total, free, short and long chain) were analyzed in cord blood of cystic fibrosis (n = 5), non-CF siblings (n = 7), and controls (n = 8). Total acylcarnitine (short and long chain combined) was significantly lower (less than 0.001) in CF compared to both control groups. Total and free carnitine showed no significant differences between the three groups. These findings are compatible with disturbed fatty acid metabolism in utero and may be related to the increased energy expenditure characteristic of CF infants.

Acylation↗
PubMed1990

Disintegration of mercury disc cells in simulated gastric juice: implications for management of disc cell ingestion.

The disintegration of charged alkaline mercury button cells in simulated gastric fluid over a 24 h period has been studied. The integrity of the cells and the amount of mercury that can leak out of them were assessed. The cells raised the pH of the incubating solutions. Disruption was seen in five out of 18 cells tested in 0.1 mol/L hydrochloric acid and one out of nine in 0.9% saline. Five of the six disrupted cells were made by the same manufacturer. Major leakage of mercury only occurred after complete disintegration of the cells. The implications of these findings for the management of patients who have ingested mercury-containing button cells are discussed.

Animals↗
PubMed1990

Nephrology and astrology--is there a link?

Astrologers presume a link between the susceptibility of particular organs to disease and signs of the Zodiac. A simple test of the positive connection between renal disease and the sign of Libra was undertaken by studying the birth dates of consecutive nephrology in-patient admissions. No significant link was found on analysis, thus disproving the traditional astrologers' claims.

Astrology↗
PubMed1989

Proopiomelanocortin-derived peptides in mice with motoneurone disease.

beta-Endorphin and alpha-melanotropin immunoreactivity was detected in motor nerves in histological sections of murine skeletal muscle, using the peroxidase-antiperoxidase technique. In mice of the wobbler strain, which can inherit motoneurone disease, a significantly higher proportion of the intramuscular nerves in soleus, extensor digitorum longus and diaphragm muscles of the diseased mice were immunoreactive than in the corresponding muscles of their healthy littermates.

Aging↗