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Biomedical subjects

R L Williams

Publications and source records attributed to R L Williams.

At least 361 records · Page 20Linked to original sources
PubMed1976

Dose-related sleep disturbances induced by coffee and caffeine.

In a 13-night sleep laboratory study, each of 18 normal young adult males twice received 1 cup of warm water, 1-, 2-, and 4-cup equivalents of regular coffee, a 4-cup equivalent of decaffeinated coffee, and a 4-cup equivalent of caffeine. All beverages were administered 30 min before bedtime according to a balanced Latin-square design. Regular coffee produced dose-related changes in most standard electroencephalogram-electrooculogram (EEG-EOG) sleep parameters, and the 4-cup equivalents of regular coffee and caffeine produced equivalent effects. Decaffeinated coffee had no effect. Regular coffee and caffeine caused rapid eye movement (REM) sleep to shift to the early part of the night and stages 3 and 4 sleep to shift to the later part. Coffee also produced dose-related changes in several subjects estimates of sleep characteristics. These results suggest that coffee and caffeine may be used in normal subjects to induce symptoms mimicking those of insomnia. Such a tool should promote further understanding of insomnia.

Adult↗
PubMed1976

Interrupted aortic arch: factors influencing prognosis.

From January, 1969, to June, 1974, 11 infants with interrupted aortic arch were operated upon. Eight of them died in the perioperative period. Their cases were reviewed in an attempt to find factors influencing the prognosis. Age, weight, preoperative hemodynamics, angiographic findings, and the type of arch anomaly did not influence the outcome. The operation, whether palliative or involving intracardiac repair, did not affect the prognosis. The only factor related to the outcome was the size of the conduit: in all infants who died, the vessel used to bridge the gap (carotid or subclavian artery) was of narrow diameter. In the 3 patients who survived it was of much larger bore. We conclude that in the repair of interrupted aortic arch, an adequate conduit is essential for success.

Aorta↗
PubMed1976

Cardiovascular effects of electrical stimulation of the forebrain in the fetal lamb.

Modified stereotaxic techniques were applied to fetal lambs during the latter third of gestation. Electrical stimulation in the region of the hypothalamus in 10 acute experiments was associated with three patterns of arterial blood pressure and heart rate changes: a pressor-tachycardia response; a pure tachycardia response (abolished by propranolol); and a pure bradycardia response (abolished by atropine). The pressor-tachycardia response was examined in detail in 13 chronic preparations (115-135 days of gestation at operation). The systolic arterial blood pressure increase was never greater than 35 mm Hg and was probably blunted by the large noninnervated placental circulation. This pressure increase was abolished by phentolamine and was thus mediated by stimulation of alpha-adrenergic receptors. The initial tachycardia was prevented by propranolol and was due to beta-adrenergic stimulation. The tachycardia was followed in a few seconds by a bradycardia, abolished by atropine and possibly a vagal baroreflex. The pressor-tachycardia response was accentuated in two lambs who were delivered spontaneously and were studied after birth. These studies indicate that a suprabulbar neural framework exists in the fetal lamb for influencing the cardiovascular system from as early as 90 days of gestation.

Adrenergic beta-Antagonists↗
PubMed1976

Direct renal effects of sodium acetate in the dog.

Sodium acetate (AC) is used in clinical medicine as it provides a ready source of fixed base. The direct renal dynamics of this buffer salt are not well known. In anesthetized dogs the left renal artery was infused with solutions of AC. In concentrations of 0.1 to 0.5 muEq/min, the acetate ion was always immediately detected in the urine. There were no demonstrable renal changes in volume, PAH clearance, creatinine clearance or electrolytes during the perfusion periods. Direct infusion of AC into the renal artery did not cause any change in blood pressure. We conclude that AC in the conditions of our experiments did not cause renal vasodilation or changes in renal excretions patterns and appears to have a zero renal threshold.

Acetates↗
PubMed1976

The utility of self-management procedures in modifying the classroom behaviors of mentally retarded adolescents.

Self-management procedures including the self-recording of points, the self-graphing of progress, and the self-selecting of free time activities were applied to the classroom behaviors of 12-year-old educable mentally retarded subjects. Students were first awarded points for specified appropriate behaviors. Then during the last two treatment phases, they graphed their points earnings and used these points to earn free time activities. A multiple baseline design was used in appraising the comparative effects of these three treatment conditions during spelling and reading periods. All three treatment conditions produced higher rates of appropriate behavior than did baseline conditions; however, the highest levels of appropriate behavior were achieved during the self-selected free time phases.

Behavior Therapy↗
PubMed1975

Mefloquine (WR 142,490) in the treatment of human malaria.

Mefloquine hydrochloride, a new 4-quinolinemethanol, was administered as a single oral dose to 47 volunteers infected with malaria. Treatment resulted in rapid clearence of fever and parasitemia. No recrudescence of parasites was observed after treatment of chloroquine-sensitive infections of Plasmodium falciparum. More significantly, in nonimmune persons with chloroquine-resistant infections, 1 gram of mefloquine cured 10 of 12 patients and 1.5 grams cured all 8 patients who received this dose of the drug. The marked activity of a single dose of mefloquine against chloroquine-resistant strains of Plasmodium falciparum suggests that this agent may be more useful than currently available drugs are for the treatment of drug-resistant malaria.

Antimalarials↗
PubMed1975

Serotyping of Pseudomonas aeruginosa isolates from patients with cystic fibrosis of the pancreas.

Pseudomonas aeruginosa isolates (173) from 144 patients with cystic fibrosis (CF) of the pancreas in seven hospitals were serotyped with the agglutination systems of Homma (1974) and Fisher et al. (1969). The two systems were complementary. Strains from CF patients were much less likely to furnish a stable type on repetitive typing tests than strains from other patients. This was related to the frequent occurrence of mucoid P. aeruginosa strains. The 173 strains were divided among 11 Homma serotypes. A single Homma type (type 8) capable of mucoid growth comprised 104 (60%) CF strains. Eight serotypes were detected in 77 strains from 48 CF patients in one hospital; three strains were detected in one hospital CF unit; and two strains were detected in each of five hospital CF units. The CF serotype comprised from 50 to 93% of CF strians inthe seven hospitals. These P. aeruginosa strains dissociated in vivo as judged by mucoid and nonmucoid colonies on primary culture plates and continued to dissociate during subcultures. Both colony type were the same serotype. The tendency to regard colonial phenotypes (mucoid, nonmucoid, rough) as separate strians was erroneous. Repetitive typing with the two systems gave better results than a single system. The mucoid P. aeruginosa strain is probably spread from patient to patient, rather than acquiring its mucoid characteristic de novo in the CF patient. It is not known why the mucoid CF strain has a peculiar predilection for CF patients, nor why it generally loses the quality in culture but retains it indefinitely in the patient.

Agglutination Tests↗
PubMed1975

Spontaneous phrenic nerve activity in the exteriorized fetal lamb.

Phrenic nerve activity and tracheal pressure changes were recorded in four exteriorized fetal lambs (120-135 days gestation) from lightly anesthetized ewes to study possible mechanisms involved in the establishment of rhythmical breathing patterns. Two types of spontaneous neural activity were found. The first consisted of high-frequency multiunit bursts (mean duration 820 ms; range 450-2,500 ms) that preceded a gasp. Individual units within these bursts reached peak discharge frequencies as high as 40 impulses/s. The second type of neural activity consisted of single-unit, low-frequency (1-14 impulses/s), irregular background discharges lasting up to several seconds without changes in tracheal pressure. Occasionally, higher frequency bursts of single-unit activity were detected that were also unassociated with tracheal pressure changes. The data indicate that the neural correlate of a fetal gasp includes high-frequency synchronized bursting activity in the phrenic nerve. In addition, background phrenic activity can be detected in the exteriorized fetal lamb that reflects central nervous activity in the absence of tracheal pressure changes.

Animals↗
PubMed1975

Sleep-related penile tumescence as a function of age.

The authors conducted a study of nocturnal penile tumescence (NPT) in 125 healthy males aged 3 to 79 by means of EEG recordings to provide normative data on how general the phenomenon is, its range of charateristics, and how it is related to man's sexual function. The results indicate that NPT occurs consistently in a healthy male population, that its expression is significantly affected by age, that it is related to stage of psychosexual development, and that it is worthy of further investigation. Clinical experience indicates that it is a useful, objective method of discriminating among various types of biogenic and psychogenic impotence.

Adolescent↗
PubMed1975

Longitudinal sleep patterns during pubertal growth: four-year follow up.

There were little or no indications of differences in sleep outcomes between the sexes. Results indicate a disturbance of sleep on initial laboratory nights relative to later nights. The results reported here clearly document the persistence of these effects from year to year. For the most part, sleep characteristics during the 4 years immediately after onset of puberty appear to represent a typical phase in the gradual patterns of changes across all ages. Total sleep time decreased markedly from 560 min in age range 10-12 to 424 min in age range 20-29, with our puberty subjects as intermediate levels. Puberty subjects has an average of 2.5 awakenings/night in the first 2 years as compared with 1.2/night in the last 2 years. The number of sleep stage shifts during the night varied around a constant mean value of approximately 37/night throughout all ages. The number of rapid eye movement (REM) period during the night decreased sharply for individuals from childhood (6.9/night) through adolescence (4.0/night), remaining constant thereafter. Percentages of the various sleep stages were fairly constant for individuals from age range 10-12 through age 30-39. Our puberty subjects had percentage profiles in near perfect agreement with the normal ontogenetic process. Normative data suggest that slow wave sleep reaches a peak at some point during the teen years.

Adaptation, Physiological↗