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Biomedical subjects

G Weiss

Publications and source records attributed to G Weiss.

At least 361 records · Page 20Linked to original sources
PubMed1981

Controversial issues of the pharmacotherapy of the hyperactive child.

This paper, which forms part of a symposium on Paediatric Psychopharmacology, selects for discussion certain practical and theoretical issues related to the use of Stimulant Therapy for Hyperactive Children. The particular issues selected relate to important clinical questions, most of which have been the focus of recent research. Amongst the controversial issues chosen for discussion is the fact that while the short term effect of stimulants on symptoms of the hyperactive syndrome is well established, the long term efficacy and the effect of stimulants on improving the prognosis of this syndrome remains uncertain. It is concluded that the large body of research on the use of stimulants for hyperactive children has finally answered some long standing questions, but many gaps of knowledge remain and further research is required.

Adolescent↗
PubMed1981

Placental control of ovarian immunoreactive relaxin secretion in the pregnant rat.

To investigate the control mechanisms for the secretion of relaxin in pregnant rats, the effects of the fetus, placenta, and uterus were studied. Plasma immunoreactive relaxin and progesterone were measured in pregnant rats, from days 8--1 post partum. On day 16 of pregnancy, groups of animals were subjected to removal of the fetuses, conceptuses (fetuses and placentae), or uteri. To determine whether there are extraovarian sources of circulating relaxin, a group of pregnant rats was ovariectomized on day 16. Immunoreactive relaxin was undetectable in the plasma of pregnant rats before day 10, and increased to a mean concentration of 0.52 +/- 0.01 (SEM) ng/ml on day 13. In control animals, immunoreactive relaxin levels remained at about this concentration throughout the remainder of pregnancy and declined rapidly post partum. The pattern of secretion of relaxin in fetectomized animals was similar to that in controls. In contrast, a significant decline in immunoreactive relaxin was seen, within 24 h after surgery, in those animals in which removal of the conceptuses or hysterectomy was performed. In these animals, immunoreactive relaxin was undetectable within 48 h after surgery and remained undetectable throughout the experimental period. In animals that were ovariectomized, immunoreactive relaxin was undetectable 24 h after surgery. Progesterone secretion in animals that had fetectomy or removal of the conceptuses performed was similar to that in controls. These groups showed a significant decline in progesterone on day 17 of pregnancy, and progesterone continued to decline until day 1 post partum. Progesterone in hysterectomized animals declined more abruptly than in either controls or other experimental groups. Ovariectomy resulted in a prompt fall in plasma progesterone. These results indicate that in the rat, the fetus is not needed for the maintenance of relaxin secretion throughout pregnancy, the placenta controls the ovarian secretion of relaxin. The uterus does not exert a tropic effect upon relaxin secretion, no extraovarian sources of circulating relaxin exist in the rat, and there is a divergence between progesterone and relaxin secretion during rat pregnancy.

Animals↗
PubMed1981

Hormone secretion by monolayer cultures of human luteal cells.

To be able to study the control mechanisms for human luteal function, a system was designed to maintain human luteal cells in culture. Collagenase dispersed cells of human corpora lutea of the menstrual cycle and pregnancy were maintained as monolayer cultures for 26 days. Progesterone (P) and relaxin (R) in culture media were measured by radioimmunoassay. Both menstrual cycle and pregnancy luteal cells secreted P for 26 days. hCG increased P secretion by menstrual cycle luteal cells, but not by pregnancy luteal cells. R was not detected in media of menstrual cycle luteal cell controls, nor in media of cells incubated with hCG. R was detected in media of pregnancy luteal cells for 6 days. Addition of hCG caused a significant increase in media R levels only on day 2 of culture. These studies show that human luteal cells can be maintained as viable monolayer cultures for at least 26 days and these cultures can be used to study control of human luteal function.

Cells, Cultured↗
PubMed1980

Myometrial inhibiting activity of relaxin-containing extracts of human corpora lutea of pregnancy.

Relaxin is a peptide hormone secreted by the human corpus luteum of pregnancy . Aqueous extracts of relaxin-rich pregnancy corpora lutea decreased the amplitude of spontaneous human myometrial strip contractions in vitro. Relaxin-poor extracts of menstrual cycle corpora lutea did not affect contractions. Antibody precipitation of relaxin from pregnancy luteal extracts eliminated the effect on myometrial strips. Relaxin removal was confirmed by bioassay. This demonstrates an inhibiting action of human relaxin on human myometrial tissue in vitro. This action suggests a mechanism for maintaining uterine quiesence in early pregnancy.

Corpus Luteum↗
PubMed1980

Ketazolam and diazepam in anxiety: a controlled study.

Ketazolam (both in once-daily and three-times-daily dosing), diazepam, and placebo were compared for effectiveness in relieving anxious symptomatology in a clinical trial conducted with a total of 222 anxious, non-psychotic outpatients. Results indicated that improvement occurred early in treatment, that ketazolam was equally effective in both once-daily and three-times-daily dosing, and that ketazolam was similar in effect to diazepam. Ketazolam (both once-daily and three-times-daily) and diazepam were significantly (P < 0.05) better than placebo in alleviating symptoms of anxiety, as measured by the Hamilton Anxiety Scale, the Covi Anxiety Scale, and a physician-rated measure of global improvement.

Adult↗
PubMed1980

[Aflatoxin M1 in milk and milk products. A comparison of some determination procedures].

Usual TLC-methods for the determination of Aflatoxin M1 in milk and milk products sometimes do not separate interfering substances with similar optical and chemical properties from Aflatoxin M1, thus leading to considerably incorrect results. Even after an additional clean-up on polystyrene column the solutions contain so many compounds that the identification of Aflatoxin M1 is difficult. The resolving power of HPLC yield pure frations, which may be determined by their MS and UV spectra.

Aflatoxin M1↗
PubMed1980

On the problem of milling and ultrasonic treatment of asbestos and glass fibers in biological and analytical applications.

In preparing fiber suspensions for biological applications, as well as in many analytical procedures, the fibers--e.g. asbestos and glass--often have to be mechanically diminished and ultrasonically treated. Such treatments may sometimes produce changes in the physical and chemical properties of the original fiber samples. Measurements have been made to estimate the changes in fiber shape, size, and structure after milling and ultrasonic treatment. The results have shown that milling procedures not only change the size distribution, but also the particle shape and crystal structure of asbestos fibers. Ultrasonic energy (50 kHz) had practically no influence on the crystal structure, but in long-term applications it produces changes in fiber size and fiber concentration.

Asbestos↗
PubMed1980

Hyperactives as young adults: self-esteem and social skills.

Eighteen pairs of young adult hyperactives and controls, matched for age, sex, IQ and socioeconomic class and education completed, were assessed on tests of social skills and self-esteem. Hyperactive subjects had significantly more difficulty than matched controls in social skills tests which involved direct oral responses than those involving written responses. This would suggest that the hyperactive young adults cognitively know what the most appropriate response would be from a number of possibilities, but have problems spontaneously producing such a response. Situations dealing with heterosocial and assertion situations were more difficult for hyperactives than job interview situations. Hyperactive young adults also scored significantly worse than matched controls on a number of self-esteem tests, thus supporting the findings of previous psychiatric assessments and the California Psychological Inventory. Finally, no significant correlations were found between the self-esteem and social skills tests. Possible explanations for the findings are discussed.

Adolescent↗
PubMed1980

Induction of relaxin secretion in nonpregnant women by human chorionic gonadotropin.

Five normal women using barrier forms of contraception has serum samples drawn every 2 days during control menstrual cycles. Relaxin was not detectable in their serum. All five subjects then received 2500 IU hCG im every 2 days beginning 8--10 days after presumed ovulation. All had immunoreactive relaxin detectable in serum 2--6 days after the first hCG injection. Relaxin rose to pregnancy levels (range, 0.26--0.62 ng/ml; mean, 0.38 +/- 0.17 ng/ml) by cycle day 31 and then declined before menstruation. Progesterone levels and cycle lengths of relaxin-secreting cycles were significantly higher (P less than 0.05) than control cycles. Three of the five subjects subsequently received 2500 IU hCG im every 2 days commencing 2--3 days after presumed ovulation until menstruation. Relaxin was not detectable in these cycles. hCG can induce relaxin secretion in nonpregnant women. A hCG stimulus which can induce relaxin secretion from an 8- to 10-day-old corpus luteum cannot induce relaxin secretion in a 2- to 3-day-old corpus luteum, suggesting that the age of the human corpus luteum of the menstrual cycle is an important determinant of responsiveness to hCG.

Chorionic Gonadotropin↗
PubMed1980

Functional comparison of coronary bypass grafts of the saphenous vein and internal mammary artery.

The magnitude and distribution of myocardial blood flow through a saphenous vein (SV) bypass graft and an internal mammary artery (IMA) graft (diameter greater than or equal to 2 mm) into the same left anterior descending coronary artery (LAD) (diameter congruent to 1.5 mm) were determined at rest, with atrial pacing, and with elevated left ventricular end-diastolic pressure (LVEDP) in 18 dogs. Blood flows through the native LAD, SV, and IMA grafts were similar in the resting heart. With atrial pacing (heart rate = 150% of control), flow in both the SV and IMA grafts increased but the difference was not significant. With elevated LVEDP (20 mm Hg) produced by transfusion, flow in both SV and IMA grafts increased, but, again, these increases were not significantly different. The SV and IMA bypass grafts have similar flow rates at rest and during increased functional demand, provided the grafts are larger than the vessels into which they are placed.

Animals↗