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Biomedical subjects

L Nelson

Publications and source records attributed to L Nelson.

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

Adrenergic stimulation of sea urchin sperm cells.

The noradrenergic agonists norepinephrine and isoproterenol elicit greater stimulatory swimming responses in sea urchin spermatozoa than epinephrine. The beta-blocker atenolol induces an even greater motile rate, while the alpha-blocker phentolamine has only a moderate effect, it also causes a minimal reduction in the sperm cells' response to atenolol. Caffeine increases the motility but to a lesser degree than 8-Br-cAMP. In drug interaction assays, both caffeine and 8-Br-cAMP depress the adrenergic effects. Agents that affect access of calcium to the flagellar apparatus (verapamil and trifluoperazine) depress the motility below the level of the controls when incubated separately with the sperm suspensions and counteract the stimulation due to atenolol. Adrenergic modulation of sperm motility thus appears to be both a calcium-dependent and a cyclic nucleotide-dependent process.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1989

Ambiguous-handedness: incidence in a non-clinical sample.

Using a handedness demonstration preference test under simple and complex task conditions, incidence rates for right, left, and mixed hand preferences were identified in a non-clinical sample. A relatively low incidence rate of ambiguous-handedness was also demonstrated, supporting earlier hypotheses that this subtype is rare among normals.

Adult↗
PubMed1989

Is there atypical handedness in schizophrenia?

Ninety-three schizophrenic patients and 105 normal controls were tested in a single session on an 8-item repeat-administration handedness test. The schizophrenic group, in contrast to the normal controls, showed a shift in the distribution away from right-handedness, which was due to an increase in the proportion of mixed-handers. Additional analyses revealed that the increase in mixed-handedness was largely due to an increase of within-item variability in the schizophrenic group, which we refer to as ambiguous handedness. Nearly 20% of the schizophrenic patients were inconsistent on 3 or more items compared with 3.8% of the normal controls. This increased incidence of atypical handedness is discussed within the context of disorders of attention and neurodevelopment.

Adult↗
PubMed1989

Laboratory evaluation of differential white blood cell count information from the Coulter S-plus IV and Technicon H-1 in patient populations requiring rapid "turnaround" time.

Automated differential counts produced by the Coulter S-Plus IV (S + 4) and the Technicon H-1 (H-1) were compared with routine and reference manual differentials with the use of samples from the adult emergency room (ER) and the neonatal intensive care unit (NICU), populations in which rapid reporting of laboratory results is considered important. Error rates for routine technologists were 9.3% in the ER and 15.3% in the NICU. Error rates for the two instruments were higher than those for technologists with samples from the ER but could be reduced to 4-5% if instrument flags and additional criteria were used to signal the need for a conventional differential. Instrument error rates were higher yet with NICU samples, and specificity was very low (10% for each device). There were small differences between the instruments in detection of immature neutrophils, but flags from the H-1 were more specific (except for detection of nucleated red blood cells in samples from the ER). If either instrument were used in an adult ER and flags and additional criteria were used to signal the need for conventional differentials, 64-75% fewer manual counts would be performed with no decrease in accuracy and a considerable improvement in turnaround time.

Blood Specimen Collection↗
PubMed1989

Intravenous glucose tolerance and pancreatic islet beta-cell function in patients with multiple sclerosis during 2-yr treatment with cyclosporin.

Cyclosporin is an immunosuppressive drug used with increasing frequency in patients with diabetes mellitus both as experimental primary therapy for insulin-dependent diabetes mellitus and as therapy accompanying pancreatic transplantation. However, reports have appeared contending that cyclosporin causes glucose intolerance and inhibits pancreatic islet beta-cell function. Consequently, concern has been raised that the beneficial effects of immunosuppression may be offset by adverse metabolic effects of the drug. To address this issue, we examined intravenous glucose tolerance and pancreatic islet beta-cell function in a group of nondiabetic multiple sclerosis patients before and during a 2-yr course of cyclosporin or placebo therapy. Patients were randomly assigned to one of the two drug groups and followed in a double-blind manner. Basal levels of glucose, insulin, and C-peptide as well as glucose disappearance rates and pancreatic islet beta-cell function after stimulation with intravenous glucose and arginine were determined immediately before therapy and after 3 wk, 6 mo, 1 yr, and 2 yr of therapy. No abnormalities in these parameters were observed in the cyclosporin of the placebo-treated group. It appears that cyclosporin can be give in conventional doses for as long as 2 yr without encountering evidence for impaired glucose homeostasis. However, whether adverse effects will materialize over longer periods of drug use remains a question.

Adolescent↗
PubMed1989

Glucose homeostasis and insulin secretion during chronic treatment with cyclosporin in nondiabetic humans.

Cyclosporin or placebo was administered in a randomized, double-blind fashion to 13 patients with multiple sclerosis for 1 yr to determine whether cyclosporin adversely affects glucose homeostasis or beta-cell function. No significant differences were observed in fasting glucose, fasting insulin, intravenous glucose tolerance, or glucose-induced insulin secretion before treatment or at 3 wk, 6 mo, or 1 yr during treatment. Longer therapeutic trials with larger patient groups will be necessary to decide whether cyclosporin can be safely given for many years without risk of developing diabetes mellitus.

Blood Glucose↗
PubMed1989

Exercise, cardiovascular disease and blood pressure.

The "chronic" effect of exercise on blood pressure has been controversial and the debate has been confused by a large number of studies with inadequate methodology. Recent consistent findings in epidemiological, experimental and longitudinal intervention studies have suggested that a true antihypertensive effect which is independent of confounding effects of sodium intake, weight, etc. is more likely than not. Unlike some other measures of lowering blood pressure such as sodium restriction, alcohol moderation and some drugs, regular exercise is associated with beneficial effects on several risk factors and probably has an independent effect on cardiovascular mortality. The magnitude of the effect in previously sedentary subjects is greater than that of dietary measures which lower blood pressure except for weight reduction in the obese. Long-term effects on blood pressure are supported by evidence of a favourable influence on left ventricular hypertrophy. The mechanisms involved in the antihypertensive effect of exercise are unclear, but sympathetic withdrawal is one factor involved. Present evidence appears sufficient to include regular exercise amongst the useful therapies for hypertension.

Animals↗
PubMed1989

Milking and feeding-induced release of the gastrointestinal hormones gastrin and somatostatin in dairy cows.

In monogastric animals, suckling influences the secretion of gastrointestinal hormones during lactation. The aim of the present study was to investigate whether similar effects are induced by milking in cows. Experiments were performed on four cows in midlactation. Blood samples were drawn from a chronic jugular vein catheter and gastrin, and somatostatin were determined by radioimmunoassay. Milking and feeding increased plasma gastrin. Somatostatin increased at morning milking and at feeding, but it decreased at evening milking. Atropine injected subcutaneously 30 min before milking increased resting concentrations of gastrin but decreased resting concentrations of somatostatin. Feeding-induced release of gastrin remained but the milking-induced release disappeared. The milking- and feeding-induced effect on somatostatin became more marked. We suggest that milking influences gastrin and somatostatin via activation of the vagal nerves. The gastrin release caused by milking may be mediated via a cholinergic mechanism, whereas the atropine resistant effect on gastrin caused by feeding and on somatostatin caused by both milking and feeding suggest that a noncholinergic, perhaps peptidergic, transmitter may be involved.

Animals↗
PubMed1988

Allergic rhinitis.

Explore the source record for details and available documents.

Desensitization, Immunologic↗
PubMed1987

Effect of autonomic blockade on the hemodynamic responses of normal human subjects to acute intravenous milrinone.

We studied the hemodynamic effects of four doses of milrinone, administered by intravenous (i.v.) infusion alone and after autonomic blockade with prazosin, propranolol, atropine, and clonidine. Plasma concentrations of milrinone (50-600 ng/ml) were similar to those used for the treatment of cardiac failure and were unaltered by autonomic blockade. When given alone, milrinone induced dose-dependent increases in heart rate (maximum increase 21 +/- 4, SEM, beats/min) and cardiac output (CO) (maximum 44 +/- 9%) and reduced systemic vascular resistance (SVR) by a maximum of 32 +/- 5%. After autonomic blockade, milrinone caused a similar fall in SVR and a smaller but significant (7 +/- 2 beats/min) rise in heart rate, but no change in CO. The increase in CO produced in normal humans by acute i.v. infusions of milrinone depends on intact cardiovascular reflexes.

Adult↗
PubMed1987

The place of exercise in the long-term treatment of hypertension.

The antihypertensive effects of exercise have been examined in 2 randomized studies of multiple levels of activity. In 12 normal subjects, 1 month's exercise 3 times weekly lowered blood pressure (BP) and vascular resistance. There was only a slightly greater effect after 7 times/week exercise. In most subjects there was a marked reduction in noradrenaline spillover rate, a measure of sympathetic activity. Exercise also improved glucose utilization and lowered plasma cholesterol. Thirteen previously untreated patients with essential hypertension had an average fall in BP of 11/9 and 16/11 mm Hg after 1 month each of 3/week and 7/week exercise respectively, again associated with fall in vascular resistance and a 20-30% reduction in plasma noradrenaline. BP remained lowered by 3/week exercise for 1 year. In patients who had BP controlled with drug for greater than 1 year, exercise 3 times weekly also prevented the redevelopment of hypertension after long-term drug therapy was ceased. Regular exercise is useful in the initial management of patients with mild hypertension. In more severely hypertensive patients, exercise may also be effective after an initial period of drug therapy.

Blood Pressure↗
PubMed1987

Comparison of some screening tests for detecting mastitis.

Quarter milk samples were analyzed for somatic cell counts, ATP, NAGase, bovine serum albumin, antitrypsin, conductivity, and bacteriological findings. The diagnostic tests were compared with respect to their ability to predict the infection status of a quarter on test day. Predictive ability was evaluated by logistic regression. All components measured increased in the presence of infection. Correlations between components were higher in quarters with pathogens than in quarters free from infection. Predictive ability was highest for ATP, somatic cell counts, and NAGase. Comparisons within udder using ratios from different quarters gave no better prediction than absolute values. For all diagnostic tests except conductivity, combinations of absolute values and interquarter ratios were not better than predictions based on absolute values only. If conductivity is to be used to predict infection status, a combination of absolute value and interquarter evaluation is recommended. Combinations of two diagnostic tests increased the predictive ability in most cases, although the increase was only minor.

Acetylglucosamine↗
PubMed1987

Early experience of health maintenance organizations under Medicare competition demonstrations.

Between 1982 and 1985, health maintenance organizations (HMO's) entered the Medicare market under the Medicare competition demonstrations. The status and experience of these HMO's, their market areas,, and the benefit packages they offered are presented. Information from case studies of 20 of these HMO's is used to discuss the planning process through which the organizations prepared to enter the Medicare market. Data from administrative reports, submitted by the HMO's, are used to describe the operational experience, including enrollments, utilization, and financial performance.

Capitation Fee↗
PubMed1987

Focal pontine leukoencephalopathy in a patient with the Shwachman-Diamond syndrome.

A 35-year-old woman who died after a long history of an illness consistent with Shwachman-Diamond Syndrome, was found to have extensive calcified necrotizing lesions confined to the pontocerebellar fibers of the basis pontis. The possible relationship of this recently described lesion to the patient's immunosuppressed state and/or other systemic metabolic disturbances is discussed.

Adult↗
PubMed1986

Fluidity of normal and epileptogenic freeze-lesioned synaptic membranes in the cat.

Electron paramagnetic resonance spectra obtained with a 5-Nitroxylstearate spin label indicate that inhomogeneous lipid domains exist naturally in the bulk lipid matrix of cat synaptic plasma membranes at physiological temperatures, associated with non-cooperative phase transitions spanning broad temperature intervals between about 10 degrees C and 40 degrees C. These properties are qualitatively similar in normal membranes and in membranes isolated from epileptogenic freeze-lesioned brain cortex. The fluidity of matrix lipids isolated from cortex adjacent to such lesions appears to be abnormally increased at physiological temperatures, but membrane polarity, partially reflecting water penetration of the surface of the bilayer, remains normal in membranes from lesioned areas. Both fluidity and polarity of membranes isolated from 'mirror' sites contralateral to lesions appear to remain normal, and thus unaffected by seizure activity per se in these preparations, in which independent 'mirror' foci did not develop. These findings demonstrate that lipid phase inhomogeneities are present and thus may play a role in normal and abnormal functions of synaptic membranes, and that abnormalities of membrane fluidity are in fact closely associated with epileptogenesis in the freeze-lesion model.

Animals↗