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Biomedical subjects

J Williams

Publications and source records attributed to J Williams.

At least 1,045 records · Page 58Linked to original sources
PubMed1981

Variations in the plasma levels of luteinizing hormone and androstenedione and their relationship with the adult daily sperm output in cockerels raised under different photoschedules.

Circulating levels of LH and androstenedione were measured in 4 groups of 30 cockerels from 3 to 26 weeks of age. Each group was submitted to a different programme of artificial lighting, either a long (16 h) photoperiod, a short (8 h) photoperiod, an increasing (8 h to 16 h) photoperiod or a night-interruption regimen. Measurements were also made of the numbers of spermatozoa ejaculated on a daily basis between 22 and 24 weeks of age, and these data were then compared with data on the hormone levels in plasma. Certain differences in mean plasma hormone levels between groups subjected to different photoperiodic treatments were observed. Adult plasma levels of LH were lowest in birds exposed to 16 h of light per day while they were attained later in animals exposed to only 8 h of light per day. Similarly, adult plasma levels of androstenedione were attained at a later age in birds subjected to 8 h light per day than in the other treatment groups while the highest peak values, around the time of puberty, were found in cockerels receiving 8 h light in two blocks of 7 h and 1 h. Although some differences in hormone parameters were found between the best and the poorest sperm producers under certain of the lighting programmes, no relationship could be found between either the mean plasma level of LH, the duration of the pre-pubertal plateau of LH, the age at the pre-pubertal rise in LH or the age at the pre-pubertal rise in androstenedione and the level of adult fertility.

Androstenedione↗
PubMed1981

Indirect self-destructive behavior in chronic hemodialysis patients.

As one of a series of investigations of indirect self-destructive behavior, a pilot study was conducted with a group of 32 chronic hemodialysis patients for those characteristics of such behavior which had emerged as most salient in earlier studies: self-esteem, locus of control, rigidity, impulsivity, futurity, risk-taking and denial. Using an average of ratings of cooperativeness obtained from the head nurse, physician, dietician, technician, and staff nurse, the group was divided into two subgroups of more and less cooperative patients, and the demographic, medical, and psychological data from the two groups were compared. The findings suggest that the less cooperative hemodialysis patients have experienced the illness as a more severe blow to their self-concept and have failed to integrate their illness into an effective adaptive life pattern. The uncooperative patients feel less valued and less appreciated not only by their family but also by fellow patients and by hospital staff. They show significantly more anger and withdrawal than the more cooperative group and appear to have compensated for a significantly greater sense of powerlessness by the development of manipulative behaviors in relating to their medical caretakers.

Adaptation, Psychological↗
PubMed1981

Reliability of a population survey tool for measuring perceived health problems: a study of patients with osteoarthrosis.

A study is described which tested the reliability of the Nottingham Health Profile, a standardised measure of perceived health status suitable for use with both large groups and individual patients. Patients with osteoarthrosis, uncomplicated by other diagnosed conditions, were given the questionnaire to fill in on two separate occasions four weeks apart. Analysis of data showed that all sections of the profile achieved a high level of reliability with coefficients of correlation ranging from 0.77 to 0.85 on part I and from 0.44 to 0.86 on part II. Patients reported many problems in the areas of physical mobility, pain, sleep, and energy, but rather fewer in the areas of social isolation and emotional reactions. With the exception of family relationships, most respondents reported a high level of disruption of their daily activities. Patients were very consistent in the number and type of problems which they affirmed.

Adult↗
PubMed1981

Effects of an intermittent lighting schedule on the time of egg-laying and the levels of luteinizing hormone, progesterone and corticosterone in the plasma of the domestic hen.

The use of a complex lighting schedule consisting of five blocks of light and five alternating periods of darkness every 24 h completely abolished the normal pattern of egg-laying characteristic of the domestic hen. Animals tended to lay continuously and not in clutch sequences. Ovipositions were not restricted to an 8- to 10-h period of the day, instead they occurred at any time of the solar day with slightly more occurring during the hours of darkness. The preovulatory discharge of LH was not restricted to an 8- to 10-h 'open period' and the interval between the peak values of LH in the plasma and the time of lay of the corresponding egg was 32.3 h, i.e. identical to the interval found using a normal lighting schedule of 14 h light: 10 h darkness. There were some indications that minor fluctuations in the concentrations of LH in plasma occurred rhythmically with the changes in illumination, but the concentrations of progesterone showed only a single, preovulatory peak. The concentrations of corticosterone in the plasma were high and showed marked fluctations but this did not appear to affect either the levels of progesterone or the time of ovulation.

Animals↗
PubMed1981

Enhanced fecal excretion of mirex in rhesus monkeys by 5% mineral oil in the diet.

The effect of two dietary treatments upon fecal excretion of Mirex was studied in rhesus monkeys dosed with 14C-Mirex. Administration of 5% mineral oil in the diet during the first month following dosing resulted in about 50% increase in fecal excretion of Mirex. The same treatment repeated 6 months after dosing triggered about a 400% increase in fecal excretion of Mirex. Subsequent dietary administration of cholestyramine resulted in a comparably small effect of fecal excretion of Mirex. The considerable difference in the ability of mineral oil to induce the effect during the first and sixth month after dosage is likely to be due to compartmental redistribution of Mirex. Mineral oil treatment appears to effect primarily the "very deep" compartment (fatty tissues) by enhancing intestinal elimination of Mirex.

Adipose Tissue↗
PubMed1980

The electrophoresis of transferrins in urea/polyacrylamide gels.

The denaturation of transferrin by urea has been studied by (a) electrophoresis in polyacrylamide gels incorporating a urea gradient, (b) measurements of the loss of iron-binding capacity and (c) u.v. difference spectrometry. In human serum transferrin and hen ovotransferrin the N-terminal and C-terminal domains of the iron-free protein were found to denature at different urea concentrations.

Animals↗
PubMed1980

NH2-terminal sequence analysis of pro-C4, the precursor of the fourth component of guinea pig complement.

The amino acid sequence of the NH2-terminal regions of the intracellular precursor of the fourth component of guinea pig complement (pro-C4) and isolated alpha, beta, and gamma chains of native C4, synthesized by peritoneal macrophages in culture, were determined with a microradiosequencing technique. Radiolabeled pro-C4 was immunoprecipitated from cell lysates and native C4 from culture media which contained one of six 3H-amino-acids or [35S]methionine. The purity of these proteins was established and molecular weights were estimated by electrophoresis in sodium dodecyl sulfate. Seventeen of the first 22 residues of pro-C4 were identified. Fifteen of these 17 were nonpolar. The eight amino acids ascertained within the first 9 NH2-terminal residues of guinea pig pro-C4 were identical with those reported for human C4 beta chain, and identity with residues determined for guinea pig C4 beta chain was established. These data indicate that beta chain is the NH2-terminal segment of pro-C4, that no residues are cleaved from the NH2 terminus during the conversion to native C4, and that this segment of the pro-C4 molecule is conserved phylogenetically.

Amino Acid Sequence↗
PubMed1980

The distribution of iron between the metal-binding sites of transferrin human serum.

The Makey & Seal [(1976) Biochim. Biophys. Acta 453, 250--256] method of polyacrylamide-gel electrophoresis in buffer containing 6 M-urea was used to determine the distribution of iron between the N-terminal and C-terminal iron-binding sites of transferrin in human serum. In fresh serum the two sites are unequally occupied; there is preferential occupation of the N-terminal site. On incubation of the serum at 37 degrees C the preference of iron for the N-terminal site becomes more marked. On storage of serum at -15 degrees C the iron distribution changes so that there is a marked preference for the C-terminal site. Dialysis of serum against buffer at pH 7.4 also causes iron to be bound much more strongly by the C-terminal than by the N-terminal site. The original preference for the N-terminal site can be resroted to the dialysed serum by addition of the diffusible fraction.

Binding Sites↗
PubMed1980

An evaluation of the clinical potential of a comprehensive model of human respiration in artificially ventilated patients.

1. We have investigated the feasibility of accurately simulating the respiratory function of artificially ventilated patients, using a computer model of the respiratory system. Twelve patients artificially ventilated after uncomplicated cardiac bypass surgery was studied. 2. The basic information required to simulate individual ventilated subjects was measured or derived. A program was written to enable key model parameters to be adjusted automatically to match model predictions to these clinical measurements. On completion of this matching procedure all the variables computed by the model were compared with patient values (measured or derived) and their accuracy was assessed. 3. The matching algorithm successfully optimized parameters of the model representing metabolic activity, tissue respiratory quotient, venous admixture, physiological dead space and total body bicarbonate to match measured values for oxygen consumption, carbon dioxide production, Pa, O2, PaCO2, and arterial HCO3- respectively. Other variables compared arise from the solution of equations within the model and correlation between model and patient values is generally good (r greater than 0.9). However, values of Pv-, O2 correlate less well (r = 0.85). Factors affecting the accuracy of patient simulation are discussed and some deficiencies analysed. 4. The creation of an accurate, steady-state representation of a patient by the model opens up the possibility of using it interactively as an aid to clinical management. Some possible future developments of the technique are discussed.

Blood↗