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Biomedical subjects

K Ryan

Publications and source records attributed to K Ryan.

At least 91 records · Page 5Linked to original sources
PubMed1987

The effect of ethanol and acetaldehyde on Na pump function in cultured rat heart cells.

To further define the sarcolemmal effects of ethanol and acetaldehyde, their effects on Na pump function were studied in synchronously contracting monolayers of neonatal rat myocardial cells. The effects of ethanol (10 mg/dl to 1000 mg/dl: 2 X 10(-3) M-0.2 M) and acetaldehyde (10(-6) M to 10(-4) M) on total 42K influx, ouabain-sensitive 42K influx, Na pump density (from specific 3H-ouabain binding) and pump turnover rates were measured. Applied acutely ethanol had no effect on 42K influx but after 30 min of treatment 42K influx was decreased by 13%, 23% and 48% in 100 mg/dl, 300 mg/dl and 1000 mg/dl ethanol respectively. This primarily reflected a decrease in mean ouabain-sensitive K+ influx from a control of 12.54 to 9.90, 8.95 and 6.68 (p-mol/cm2/s) in 100, 300 and 1000 mg/dl (2 X 10(-2) M, 6 X 10(-2) M) ethanol. Acetaldehyde in the concentrations tested had no effect on K+ influx. Ethanol treatment produced a decrease in Na pump density, maximum within 30 min and dose-dependent, at concentrations of 100 mg/dl (22%), 300 mg/dl (37%) and 1000 mg/dl (55%). Acetaldehyde had no effect on Na pump density. In the presence of ethanol (300 mg/dl and 1000 mg/dl) intracellular Na+ increased significantly and the Na+ efflux declined in parallel with the K+ influx. From the ouabain-sensitive K+ and Na+ fluxes and the Na pump density individual pump turnover rates were calculated at 62.5/s in control cells and 66/s and 84/s in cells treated with 300 mg/dl (6 X 10(-2) M) and 1000 mg/dl (0.2 M) respectively. We conclude that ethanol, but not acetaldehyde has a depressant effect on sarcolemmal Na pump function. The results suggest this is due primarily to a decrease in the number of sarcolemmal Na pump sites.

Acetaldehyde↗
PubMed1987

Effects of acute, in utero, alcohol exposure on growth and electrolyte metabolism in male offspring of C57BL/10J mice.

The effects of acute low-dose maternal alcohol exposures were investigated in C57B1/10J mice offspring. Pregnant mice were randomly placed into three alcohol groups and were injected twice intraperitoneally on gestation day 7, 0 hours and gestation day 7, 4 hours, with one of the following dosages of 25% alcohol: Group 2 received 1.25 Gm/Kg body weight; Group 3 2.50 Gm/Kg body wt.; Group 4 3.75 Gm/Kg body wt. A control group (Group 1) received .015 ml/gm body wt. of physiological saline. At birth all offspring were weighed and observed for any gross physical abnormalities. On day 25, all female offspring and mothers were sacrificed. The male pups were maintained until day 61. On day 61, the male pups were placed in individual metabolic cages where food and water consumption, and urine excretion were monitored for 24 hrs. On day 62, these animals were sacrificed. Blood was drawn for serum calcium (Ca) and phosphorous (P) determination. Brains, kidneys, testes, hearts and thymus glands were removed and weighed. Ca and P levels were also measured in the urine. No significant difference in litter size and fetal weight was obtained among the four groups. There was no evidence of physical abnormalities in the alcohol groups compared to the control one. The 62 day old pups from all three alcohol groups had significantly lower serum and urine levels of Ca and P than the control group, with the lowest values recorded for Group 4. There was no significant difference in final body weight but small organ size differences were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Maternal social support as a predictor of mother-child stress and stimulation.

There is increasing interest in the role of social support in determining risk for child abuse and neglect. The present study assessed the relationship between maternal social support and two areas: stress in the mother-child relationship: and level of stimulation provided in the home. Maternal social support was assessed prenatally and at a two-year follow-up, while the latter variables were compiled at the two-year follow-up. The data were obtained from 38 urban, low SES (80% on public assistance) mothers and their 2-year-old children. Maternal social support correlated positively with level of stimulation and negatively with level of mother-child stress, and was the best predictor of both, relative to any SES, mother or child variables. In addition, high stress, low support mothers provided significantly less stimulation to their children. The theoretical implications for social support as a mediator variable as well as its implications for early identification and prevention efforts in abuse and neglect are discussed.

Adolescent↗
PubMed1985

Biphasic progesterone synthesis by the hamster preovulatory follicle in vitro.

In vitro time course studies of progesterone and protein synthesis by hamster preovulatory follicles (harvested prior to the proestrous gonadotropin surge) were done. LH appears to stimulate progesterone synthesis in 2 phases. The first phase lasts 0 to 4 or 5 hr and is not inhibited by either puromycin or cycloheximide. The second phase (apparent by 4-5 hr) is distinguished from the first phase by its inhibition by puromycin and cycloheximide, and by the differential dose response of dibutyryl cyclic AMP on the respective 2 phases. Incorporation of a H-labelled mixture of amino acids into protein is not seen in LH-stimulated follicles in 2 hr incubations but is apparent by 4 hr. The LH-stimulated protein synthesis is inhibited by puromycin. The results indicate that although LH stimulates both phases of progesterone synthesis, the mechanisms may be different for each phase.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Signal modality and choice between signaled and unsignaled food.

Choice between signaled and unsignaled response-independent food schedules was assessed in three experiments using a commitment procedure. In Experiment 1, subjects tested with a 5-s visual signal consistently changed from the signaled to the unsignaled schedule. Changing from the unsignaled to the signaled schedule was observed only occasionally and only at low levels. The same outcome was observed in Experiment 2 with different types of visual signals and with different stimulus combinations identifying the signal period, the signal-absent period, and the unsignaled schedule. In Experiment 3 the visual signal was replaced with an auditory signal for four of the subjects tested in Experiment 2. The subjects then changed from the unsignaled to the signaled schedule or showed a substantial reduction in choice for the unsignaled schedule. The data were assessed using a conditioned-reinforcement interpretation of choice.

Journal Article↗
PubMed1983

Factors affecting choice of signaled or unsignaled food schedules.

Choice between signaled and unsignaled food schedules was assessed in two experiments using a shuttlebox. Experiment 1 examined preference with both a five-second signal and a thirty-second signal. Subjects preferred the unsignaled side with a five-second signal but preferred the signaled side with a thirty-second signal. Experiment 2 assessed preference using either a commitment procedure (a shuttle response resulted in exposure to the schedule for a fixed time) or a noncommitment procedure (each shuttle response changed the schedule in effect). Subjects preferred the signaled condition with the commitment procedure but the unsignaled condition with the noncommitment procedure. These results indicate that the discrepant findings of earlier studies are due to procedural differences involving signal duration and choice commitment. The data are consistent with a conditioned reinforcement interpretation of choice.

Journal Article↗
PubMed1982

The appreciation of imagery by schizophrenics: an interpretation of Goldstein's impairment of the abstract attitude.

Three experiments are reported in which schizophrenics are compared with other psychiatric patients on (i) the imagery value of words in their speech, (ii) their memory for words differing in imagery value, and (iii) their ability to distinguish the imagery value of two words. The study was designed to evaluate a neglected interpretation of Goldstein's ideas that schizophrenics are more concrete, in that their 'action is determined by momentary sense impressions'. The results gave no support for this interpretation and it is suggested that an abnormal way of categorizing the world is more likely to be a useful way of formulating Goldstein's ideas.

Adult↗
PubMed1981

Choosing schedules of signaled appetitive events over schedules of unsignaled ones.

Two experiments were completed allowing albino rats to choose between signaled and unsignaled reward conditions. These experiments examined the effects on preference of (1) response dependent versus response-independent reward and, (2) food pellets versus chocolate milk as the reward. All subjects preferred the signaled condition over the unsignaled condition, whether exposed to response-dependent, or to response-independent delivery of rewards. Preference was controlled most effectively by presenting both the signal itself and the correlated stimulus identifying the signaled condition. The signal presented alone (Extinction 3) controlled preference more effectively than did the stimulus correlated with the signaled condition (Extinction 2). The second experiment showed that the quality of the reinforcer (pellets and chocolate milk) did not affect preference for signaled reward since all subjects preferred the signaled condition at levels comparable to those observed in Experiment 1, with food pellets. These results, along with others, argue against species differences, response-dependency, and reinforcer quality as variables affecting the direction of preference.

Journal Article↗
PubMed1977

Diphosphonate therapy of paget's disease of bone.

The use of disodium ethane-1 hydroxy-1, 1-diphosphonate (EHDP) therapy for Paget's disease of bone was examined in 75 affected patients. Forty-eight patients received randomly assigned oral doses of either 0, 2.5, 5, 10, or 20 mg/kg/day in a controlled, double-blind protocol, and the remainder received either 10 or 20 mg/kg/day in a non-random protocol. The clinical status of the patients and appropriate laboratory tests were evaluated before treatment and at frequent intervals during a six-month period of initial therapy. There were no significant changes in either urinary hydroxyproline or serum alkaline phosphatase in those patients receiving placebos, while both these parameters decreased significantly at all dose levels of EHDP, with the greatest decline noted in the highest dose group. However, statistical analysis of the data related to changes in symptoms in the double-blind study revealed that patients receiving the higher dose of EHDP (10 or 20 mg/kg/day) had less favorable outcomes than those receiving the lower doses (2.5 or 5 mg/kg/day). The high does group had a relatively lower rate of symptom improvement and a relatively greater rate of deterioration than did the low dose group. Twenty-one of forty-nine patients followed for at least 18 months have shown a sustained suppression of their serum alkaline phosphatase and urinary hydroxyproline values for 12 months following cessation of EHDP, while therapy has been reinstituted for the other 28 patients because of increases in these measurements, with or without accompanying symptomatic deterioration. Eight patients sustained fractures through Pagetic bone during the period of study and all of these were treated with higher doses of EHDP. On the basis of the biochemical and clinical data in this study it appears that initial therapy of Paget's disease of bone with 5 mg EHDP/kg/day maximizes benefits while minimizing possible adverse effects.

Alkaline Phosphatase↗