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Biomedical subjects

R Fleming

Publications and source records attributed to R Fleming.

At least 91 records · Page 5Linked to original sources
PubMed1984

The use of ion exchange to remove aluminum from water used in hemodialysis.

Since the established techniques for removing aluminum from the water used in dialysis (reverse osmosis and deionization) are relatively complex and expensive, it was decided to investigate a number of simple ion-exchange techniques. In 48 of 217 tap water samples obtained from 61 home hemodialysis patients in southeast Scotland, the aluminum content exceeded 2 mumol/L (54 micrograms/L)--a level that has been associated with dialysis dementia and fracturing osteodystrophy. Dialysate prepared from this water after softening had approximately half this aluminum content, but in 17 instances the concentration still exceeded 2 mumol/L. In vitro studies showed that the anion-exchange resin IRA 400 (Rohm-Haas, Philadelphia) in the chloride phase was very effective at removing aluminum. A commercial water softener was modified by the addition of this resin, and installed in the home dialysis training unit at the Princess Alexandra Hospital in Brisbane. Over a 12-month period in which the tap water aluminum content averaged over 10 mumol/L (270 micrograms/L), the product water had an aluminum content consistently under 2 mumol/L, being under 1 mumol/L (27 micrograms/L) on 19 out of 20 occasions. The modified softener was regenerated with a saturated sodium chloride solution at 2-week intervals, using the manufacturer's protocol for the unmodified softener. Provided that dialysate and plasma aluminum levels are monitored on a regular basis, it is felt that this simple technique of aluminum removal may be appropriate for many home hemodialysis situations.

Aluminum↗
PubMed1984

Toward an integrative approach to the study of stress.

Stress and coping are considered as part of a process involving environmental events, psychosocial processes, and physiological response. The concept of stress as well as approaches to its study are discussed. Links between coping and perceived control are described, and measurement approaches are evaluated. The usefulness of integrated approaches to the study of stress, emphasizing expansion of both conceptual and methodological perspectives, is discussed.

Adaptation, Psychological↗
PubMed1984

Behavioral and biochemical effects of job loss and unemployment stress.

Previous research on the effects of unemployment has focused upon both anticipation of job loss and long-term unemployment, typically using self-report and some biochemical measures of response to unemployment stress. The present study was concerned with behavioral and biochemical responses to unemployment. It was also designed to examine a somewhat different time course of unemployment than has been used in previous work. Results indicated that stress accompanies unemployment; looking at people who had been unemployed for up to four months, those who had been unemployed for greater lengths of time performed more poorly on a behavioral task and exhibited higher levels of urinary norepinephrine and epinephrine than did persons unemployed for shorter time periods or subjects who were employed.

Adult↗
PubMed1984

Automatic control in anesthesia: a comparison in performance between the anesthetist and the machine.

This report is divided into two parts. First, we developed two new servo control systems by modifying an existing one. The original system was designed to control inspired halothane concentration using mean arterial pressure; the two new systems were designed to control inspired halothane concentration using end-tidal concentration or to control mean arterial pressure using the automated infusion of nitroprusside. Second, we compared the performance of experienced physician and nurse anesthetists (nine, six, and six experiments, respectively). The experiments incorporated a standardized testing sequence of two changes in desired blood pressure (set point) and two pharmacologically induced disturbances in blood pressure (perturbations). The scoring was designed to examine how fast blood pressure changed (90% response time), how far past the set point it went (overshoot), how long it took to eliminate most of the fluctuations in blood pressure (settling time), and the degree of fluctuation of blood pressure after settling (stability). Given three systems to be tested, there were (3 X 14) 42 possible mean scores for the machine and 42 for the anesthetists. The machine scored better than the anesthetists in 38 out of 42 of the mean scores; the differences were statistically significant in 19 out of 42 scores. The wide scatter in performances of the anesthetists prevented the achievement of significance in nine cases with large differences between means. Thus when the scores from the three systems were combined to achieve a larger n value, the machine outperformed the anesthetist in 12 out of 14 scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1983

Kinetics and thermodynamics of interfacial transfer.

The kinetic barrier against the transport of methyl and ethyl nicotinates across the water-isopropyl myristate interface has been studied as a function of temperature using a rotating diffusion cell. The temperature dependence of the interfacial transfer kinetics has enabled calculation of the thermodynamic parameters for the process. It is evident from the results that, for the transferring solutes considered, the activation energy barrier is enthalpic, because there is a large positive entropy for transfer into the interfacial region.

Diffusion↗
PubMed1983

Pregnancy-associated changes in the physical and microscopic characteristics of the ovine cervix.

Ovine cervices were obtained at slaughter from 18 sheep comprising six groups of three--cycling ewe lambs, non-pregnant, and four groups of pregnant animals of progressively longer gestation PI to PIV. Physical and microscopic analyses carried out on these cervices showed consistent results throughout any individual tissue. A number of factors changed with increasing gestational age and some of these changes were noted from early gestation. No significant change in water content was observed through pregnancy. With increasing length of gestation the cervix increased in length and width, there were relative increases in fibroblasts, smooth muscle and softening of the tissue, and relative decreases in collagen and fibrocytes. An increased vascularity was observed in the tissues from late gestation sheep, and a change in the nature of the epithelial secretion, from neutral to acidic mucins, was also associated with late pregnancy.

Animals↗
PubMed1982

Mediating influences of social support on stress at Three Mile Island.

Symptom reporting, task performance, and urinary catecholamine excretion were studied in a group of people living near the Three Mile Island nuclear power plant and in control populations. More than a year after the accident, living near the damaged reactor was associated with elevations in all indices of stress compared with control levels. Social support mediated these stress indices such that higher levels were associated with fewer psychological and behavioral symptoms of stress. Biochemical measures showed a different pattern of results.

Analysis of Variance↗
PubMed1982

LHRH analogues can be luteotrophic.

Seven normally menstruating women were treated with consecutive daily supraoptimal doses of the LHRH analogue Hoe 766 initiated in the mid/late luteal phase. This treatment caused immediate increases in circulating levels of LH, FSH, oestradiol (E2) and progesterone. After a few days, the pituitary became unresponsive to Hoe 766 and LH and FSH levels returned to the normal luteal phase ranges while progesterone and E2 levels did not decline to their respective pre-treatment levels until at least 24 h later. As a result of this treatment, the onset of the next menses was delayed in five of the seven women, indicating luteotrophism. These data show that the corpus luteum was responsive to increased LH/FSH during Hoe 766 therapy. Therefore, reported luteolytic effects of short-term treatment with LHRH and/or its analogues were probably not caused by direct inhibitory ovarian action but by reduction of ensuing pituitary gonadotrophin levels.

Adult↗
PubMed1982

Prediction of ovulation in women using a rapid progesterone radioimmunoassay.

A rapid (3-h) radioimmunoassay of plasma progesterone has been developed and used successfully to predict the time of ovulation in women undergoing artificial insemination. The results obtained using progesterone levels to date the stage of the cycle were analysed retrospectively by (1) estimation of the length of the ensuing luteal phases and comparison of these with luteal phase lengths of a control group (2) comparison of the dating using progesterone levels with retrospective determination of LH values and (3) analysis of the dating in cycles in which conception occurred.

Female↗
PubMed1982

A new systematic treatment for infertile women with abnormal hormone profiles.

Five infertile women, with normal menstrual rhythm who had been investigated previously by daily hormone analyses throughout at least one complete menstrual cycle and had shown poor luteal-phase steroid-hormone profiles were treated by a new approach. They were rendered hypogonadotrophic with large doses of a luteinizing hormone releasing-hormone analogue (Hoe 766) and were then treated with exogenous gonadotrophins to induce follicular growth and ovulation. Progesterone production after ovulation in all cases was superior to that observed in the individual patients' without treatment. One patients conceived in her first conception cycle and another in her fourth. This regimen offers a systematic approach to the treatment of unexplained infertility in women with deficient luteal-phase steroid-hormone profiles.

Buserelin↗
PubMed1982

Effects of clomiphene treatment on infertile women with normal menstrual rhythm.

Fourteen infertile women with normal menstrual rhythm were investigated; each provided daily blood samples throughout two menstrual cycles: one control cycle and another on therapy with clomiphene (50 mg/day) given either from days 1 to 5 (n = 7; group I) or from days 5 to 9 (n = 7; group II) of the cycle. The effects of this empirical clomiphene therapy on the menstrual cycles were assessed by reference to the delay from termination of clomiphene therapy to ovulation (day after the LH peak) and by comparing pre-ovulatory oestradiol levels and luteal phase progesterone indices (total progesterone levels from days 4 to 8 post LH peak) in patients' control and treated cycles. No differences were observed in the effects of the treatment on the two groups of women except that the clomiphene to ovulation delay was greater in those treated earlier in the cycle (group I). Clomiphene caused increased follicular development as indicated by elevated pre-ovulatory oestradiol levels but this was not followed by improved progesterone indices. Ovarian ultrasonography indicated that the increased follicular development was in terms of numbers of follicles and not in maturity or oestrogen biosynthetic capacity of individual follicles. The lack of increased luteal progesterone levels thereafter indicated that mean luteal progesterone production per luteinized follicle was reduced. Clomiphene therapy as given in this study was therefore not successful in stimulating increased follicular/luteal hormone production from the dominant follicle/corpus luteum in such patients.

Clomiphene↗
PubMed1982

Effect of buspirone on prolactin and growth hormone secretion in laboratory rodents and man.

Preclinical studies have shown buspirone to have some characteristics of both a dopamine (DA) agonist and antagonist. Neuroendocrine and neurochemical studies were conducted to determine which actions occur in rats and man. Buspirone produced a dose-dependent increase in rat plasma prolactin (PRL) levels and enhanced the increase in plasma PRL levels produced by alpha-methyl-p-tyrosine and gamma-butyrolactone. Buspirone also blocked the inhibitory effect of dopamine on PRL secretion in vitro, which is consistent with the action of a DA antagonist. In a double-blind placebo-controlled study using eight normal male volunteers, buspirone (30, 60, and 90 mg) produced a dose-related increase in PRL levels 60-180 minutes later, and a significant increase in growth hormone in six of the eight volunteers, which could be evidence for a DA agonist effect in the human hypothalamus. The anxiolytic effects of buspirone could be due to either DA agonist or antagonist effects.

Adult↗
PubMed1982

Diffusion of lysozyme chloride in water and aqueous potassium chloride solutions.

The diffusion of lysozyme chloride in aqueous solution has been studied at 25 degrees C using the Goüy interferometric technique. The concentration dependence of the diffusion coefficient in water has been measured over the concentration range 1.1599-9.1556 gcm-3 and the results suggest a value of D 25, w at infinite dilution of 5.838 x 10(-6) cm2s-1. The variation in diffusion coefficient with ionic strength has also been considered by following the diffusion of 0.45% lysozyme chloride in a series of potassium chloride solutions. The value of D in 0.15 M KCl has been found to be approximately one quarter of that in water alone an the diffusion coefficient has been shown to increase markedly as the KCl concentration is reduced below 0.05 M. Interpretation of these observations involves consideration of solution electrostatic effects.

Chemical Phenomena↗