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R Schulz

Publications and source records attributed to R Schulz.

At least 469 records · Page 26Linked to original sources
PubMed1989

Testosterone immunoreactivity in the seminiferous epithelium of rat testis: effect of treatment with ethane dimethanesulfonate.

Androgens drive spermatogenesis by processes that are largely unknown. Direct effects on germ cells and indirect effects mediated via testicular somatic elements are currently under consideration, and specific localization of androgens in seminiferous tubules may provide information as regards this. Adult male rats were injected with ethane dimethanesulfonate (EDS; 75 mg/kg body weight) or vehicle. Testes were fixed and paraffin-embedded for localization of testosterone immunoreactivity 1 and 2 weeks after treatment, using the unlabeled antibody (PAP) technique. Plasma testosterone dropped from a pre-treatment level of 2.3 ng/ml to below 0.2 ng/ml 3 days after EDS injection and remained at low levels until the end of observation, accompanied by a progressive decrease in testicular weight. In the seminiferous tubules of vehicle-injected males, testosterone immunoreactivity was found in nuclei of spermatocytes and spermatids and in nuclei and the cytoplasm of Sertoli cells, and showed typical variations according to the stage of spermatogenesis. One week after EDS treatment, immunoreactivity had disappeared from the seminiferous epithelium. Two weeks after treatment, staining of germ cells was detected in two out of four males. The disappearance and reappearance of immunoreactivity coincided with the time course of EDS effects on rat Leydig cells, and we conclude that it corresponds to androgen specifically localized in fixed, paraffin-embedded tissue. Because staining of germ cell nuclei varied with the stage of spermatogenesis, the technique may detect a physiologically relevant androgen fraction; its location suggests that androgens may also directly affect certain germ cell stages.

Animals↗
PubMed1989

Basal activities of adenylate and guanylate cyclase in lymphocytes and platelets of alcoholics.

Basal activities of adenylate cyclase and guanylate cyclase were determined in lymphocytes and platelets of alcoholics with different severity of alcoholic withdrawal syndrome. Compared to controls, significant changes were found in the basal activities of adenylate and guanylate cyclase in all groups of patients. Adenylate cyclase activity in lymphocytes has a positive correlation to the severity of the clinical states. Although we found increased guanylate cyclase activities in lymphocytes and decreased activities in platelets compared to controls, similar values of activities were obtained in all groups of alcoholics independently of their clinical state.

Adenylyl Cyclases↗
PubMed1989

[The correlation among pulp chamber, tooth length and tooth width in different age groups].

Computing the quotients of pulp chamber length/tooth length and pulp chamber width/tooth width for canines and lower premolars on orthopantomograms of subjects aged between 19 and 65 years led to the following result: significant reduction in length quotient and highly significant reduction in width quotient with increasing age. The reduction in width was considerably greater than in length.

Adult↗
PubMed1989

[3H]CGS 21680, a selective A2 adenosine receptor agonist directly labels A2 receptors in rat brain.

Characterization of the adenosine A2 receptor has been limited due to the lack of available ligands which have high affinity and selectivity for this adenosine receptor subtype. In the present study, the binding of a highly A2-selective agonist radioligand, [3H]CGS 21680 (2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamido adenosine) is described. [3H]CGS 21680 specific binding to rat striatal membranes was saturable, reversible and dependent upon protein concentration. Saturation studies revealed that [3H]CGS 21680 bound with high affinity (Kd = 15.5 nM) and limited capacity (apparent Bmax = 375 fmol/mg of protein) to a single class of recognition sites. Estimates of ligand affinity (16 nM) determined from association and dissociation kinetic experiments were in close agreement with the results from the saturation studies. [3H]CGS 21680 binding was greatest in striatal membranes with negligible specific binding obtained in rat cortical membranes. Adenosine agonists ligands competed for the binding of 5 nM [3H]CGS 21680 to striatal membranes with the following order of activity; CGS 21680 = 5'-N-ethylcarboxamidoadenosine greater than 2-phenylaminoadenosine (CV-1808) = 5'-N-methylcarboxamidoadenosine = 2-chloroadenosine greater than R-phenylisopropyladenosine greater than N6-cyclohexyladenosine greater than N6cyclopentyltheophylline greater than S-phenylisopropyladenosine. The nonxanthine adenosine antagonist, CGS 15943A, was the most active compound in inhibiting the binding of [3H]CGS 21680. Other adenosine antagonists inhibited binding in the following order; xanthine amine congener = (1,3-dipropyl-8-(2-amino-4-chloro)phenylxanthine greater than 1,3-dipropyl-8-cyclopentylxanthine greater than 1,3-diethyl-8-phenylxanthine greater than 8-phenyltheophylline greater than 8-cyclopentyltheophylline = xanthine carboxylic acid congener greater than 8-parasulfophenyltheophylline greater than theophylline greater than caffeine. The pharmacological profile of both adenosine agonist and antagonist compounds to compete for the binding of [3H]CGS 21680 was consistent with a selective interaction at the high affinity adenosine A2 receptor. A high positive correlation (r = 0.98, P less than .01) was observed between the pharmacological profile of adenosine ligands to inhibit the binding of [3H]CGS 21680 and the selective binding of [3H]NECA (+50 nM CPA) to high affinity A2 receptors. However, some differences between these assays were found for compounds which have moderate affinity and nonselective actions at both the A1 and A2 adenosine receptor subtypes. Unlike data obtained with nonselective adenosine ligands, the present results indicate that [3H]CGS 21680 directly labels the high affinity A2 receptor in rat brain without the need to block binding activity at the A1 receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine↗
PubMed1989

[Historic development of yeast genetics from the beginning to the first gene transformation in brewing yeast strains].

A more intensive use of the potential of brewing yeasts in the biotechnological process of brewing is based on the knowledge of the genetic background of these microorganisms. It is given a review on the stages of genetic manipulation of brewing yeasts including recombinant DNA technology which has proved to be the most successful method for a further improvement of strains.

DNA, Fungal↗
PubMed1988

Evidence for the presence of ANP-precursor material in the rat thymus.

Acidic extraction of the thymus from two day old rats followed by purification on Sephadex G-50 gelfiltration revealed the presence of atrial natriuretic peptide-like material (IR-ANP) by radioimmunoassay. Verification of the obtained immunoreactivity has been achieved by the use of two different types of antisera, i.e. two antisera directed against ANP (99-126), the other antiserum recognizing the N-terminal fragment (11-37) of the precursor ANP (1-126) molecule. In addition, reverse phase high performance liquid chromatography (RP-HPLC) and high performance gel permeation chromatography (HP-GPC) monitored by the three antisera have been employed for analysis of the extracted IR-ANP. In both systems the IR-ANP corresponded to the 15 kDa-ANP molecule (1-126). Furthermore, by using immunohistochemical techniques a distinct localization of the IR-ANP material could be demonstrated. The outer cortical area of the thymus, containing mostly lymphoid cells, showed extensive immunostaining with the three different antisera. The data reported here indicate that the rat thymus is a source of ANP.

Animals↗
PubMed1988

Monoclonal anti-idiotypic antibodies to opioid receptors.

Two monoclonal anti-idiotypic antibodies (anti-Id-135 and anti-Id-14, both of the IgM class) which interact with the binding site of opioid receptors were generated. A monoclonal anti-beta-endorphin antibody (3-E7) which displays binding characteristics for opioid ligands similar to opioid receptors served as the antigen (Gramsch, C., Meo, T., Riethmüller, G., and Herz, A., (1983) J. Neurochem. 40, 1220-1226; Meo, T., Gramsch, C., Inan, R., Höllt, V., Weber, E., Herz, A., and Riethmüller, G. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 4048-4088) and the hybridomas obtained were screened for anti-idiotypic antibodies with Fab fragments of 3-E7. The anti-idiotypes were then screened for opioid binding to rat brain membrane receptors, yielding several positive clones two of which were more intensively studied. Both anti-idiotypic antibodies were about equally potent in displacing the mu- and delta-opioid receptor ligands [3H]dihydromorphine, 125I-labeled beta-endorphin, [D-Ala2, D-Leu5-3H]enkephalin and [3H]naloxone from rat brain membrane opioid receptors; no interaction was observed with the kappa-ligands [3H]ethylketazocine or [3H]bremazocine. The anti-idiotypic antibodies were able to precipitate [3H] diprenorphine binding sites from solubilized opioid receptor preparations. In addition, both antibodies showed opioid antagonistic properties as demonstrated by their abilities to block the inhibitory effect of [D-Ala2, D-Leu5-3H]enkephalin on prostaglandin E1-stimulated cAMP accumulation in NG 108-15 hybrid cells. Our findings demonstrate the successful generation of monoclonal antibodies interacting with membrane-bound and solubilized opioid receptors of the mu- and delta-type.

Animals↗
PubMed1988

Dependence and cross-dependence in the guinea-pig myenteric plexus.

Chronic activation of opioid receptors results in the development of tolerance and dependence. Tolerance may be confined to a single receptor type and thus has been termed "selective tolerance". The present investigation reveals that prolonged activation of an inhibitory acting receptor type not only results in dependence associated with this receptor but also brings about cross-dependence. Cross-dependence involves both opioid receptors as well as nonopioid receptors, e.g. adrenoceptors. The experimental design employed did not permit conclusions to be drawn about whether those receptors exhibiting cross-dependence also developed tolerance. Regardless of the receptors and their specific subsequent transduction systems, all the receptors which showed dependence and cross-dependence proved sensitive to pertussis toxin, suggesting a critical function of GTP-binding proteins for the development of not only opioid dependence but also for drug dependence in general. Since multiple transmitter receptors may converge on the same ion channel, the concept of "convergent dependences" may be linked to GTP-binding proteins. However, no conclusions can be drawn with regard to the precise biochemical mechanisms underlying dependence.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1988

Salmon gonadotropin (sGTH) immunoreactivity and 11-oxotestosterone secretion of mature rainbow trout (Salmo gairdneri) testes in vitro: an alternative to radio-receptor assay for sGTH-binding studies.

After three intraperitoneal injections of salmon gonadotropin (sGTH) or bovine serum albumin (BSA), testicular tissue of fully mature rainbow trout was prepared for in vitro incubation with or without sGTH. The secretion of 11-oxotestosterone was measured and the tissue was fixed for light-microscopical localization of sGTH immunoreactivity (ir). Tissue from sGTH-treated males showed an increased basal secretion and sGTH-stimulated androgen secretion but the stimulated versus control ratio was higher without sGTH treatment in vivo. When the tissue had had contact with exogenous sGTH, sGTH-ir showed similar distribution patterns regardless of the sGTH treatment regimes. The extralobular compartment showed a staining of interstitial cells and capillary walls. The staining in the intralobular compartment was less clear. Many Sertoli-cells carried a faint nuclear label, whereas intralobular germ cells appeared to be unlabeled.

Animals↗
PubMed1988

Testosterone immunoreactivity in rainbow trout (Salmo gairdneri Richardson) testis.

Testosterone antiserum raised in rabbits according to conventional techniques was used to localize immunoreactive material in fixed, paraffin-embedded rainbow trout testis. Spermatogonia showed a nuclear label throughout the reproductive cycle; their nucleoli were not stained or stained less intensely. Spermatocytes displayed a staining of large cellular areas, showed an irregularly delineated intracellular label, or remained unstained; similarly stained spermatocytes were arranged in groups. Spermatids remained unstained. Spermatozoa were not labeled or were weakly labeled, which varied from male to male and also between different areas of a section. Sertoli cells showed a label confined to the nucleus. During active spermatogenesis they also carried a cytoplasmic stain. Interstitial cells with a cytoplasmic stain were found only rarely. The spermatocyte I/II transition is associated with the most considerable changes in the intracellular staining pattern.

Animals↗
PubMed1988

A longitudinal study of the psychosocial impact of stroke on primary support persons.

We investigated longitudinally the effects of a stroke on the social support systems and well-being of the patient's primary support person, both acutely and as the condition stabilized. Individuals who had suffered a first stroke and a primary support person participated in two waves of data collection, carried out in 6-month intervals beginning 7 weeks after the stroke. Our data show that the prevalence of depressive symptoms is from 2 1/2 to 3 1/2 times higher than rates found among representative samples of middle-aged and elderly populations. Mean level of depression did not change over time, although level of optimism declined significantly. Multiple regression analyses showed that levels of depression and perceived burden in support persons are highly related to aspects of the stroke such as its severity, and that demographic variables such as age and income play a relatively minor role in attenuating these relations in the acute adjustment phase. However, from 7 to 9 months after the stroke, well-established demographic variables such as health, income, and age were significant predictors of depression. Individuals who were older and who had good health and higher incomes were least depressed.

Adaptation, Psychological↗
PubMed1988

Peak performance and age among superathletes: track and field, swimming, baseball, tennis, and golf.

The purpose of this study is to identify the age of peak performance in a broad range of athletic events incorporating multiple, diverse biological systems, learned skills, and motivation. Although many researchers have noted that the absolute levels of peak performance among superathletes have improved dramatically in the last 100 years, to date no one has answered the question of stability of peak performance age over this time period. Analyses of Olympic track and field and swimming data show that the age at which peak performance is achieved has remained remarkably consistent. For both men and women, the age of peak performance increases with the length of the foot race, and women generally achieve peak performance at younger ages. The pattern of increased age with increasing distance is reversed for female swimmers, where younger ages are associated with increasing distance. For most categories of performance in baseball, the peak age of performance is equivalent to that of a long distance runner, about 28 years of age, while top tennis players reach their highest levels of performance at age 24. Golfers, in comparison, peak at about 31 years of age, although recent data suggest movement toward younger ages. A task analysis of each event is carried out, and the relative roles of biology and learning are discussed as determinants of peak performance.

Adolescent↗
PubMed1988

Sexual differentiation of the luteinizing hormone response of neonatal rats to the narcotic antagonist naloxone: critical role of estrogen receptors.

Administration of the narcotic antagonist naloxone results in an elevation of serum luteinizing hormone (LH) levels in 10-day-old female, but not male, rats. Previous studies from this laboratory indicated a role for neonatal gonadal steroids in the development of this sex-specific response. In this study, the estrogen receptor antagonist OH-Tamoxifen or the androgen-receptor antagonist flutamide were injected on Days 1 or 9 of life, and the LH responses of male and female pups to naloxone were assessed on Day 10. Flutamide did not produce a response different from that seen in vehicle-treated pups, discounting a role for androgen receptors. OH-Tamoxifen on Day 9 caused an increase in basal levels of LH; neither sex showed a response to naloxone. However, OH-Tamoxifen treatment of 1-day-old males resulted in an enhanced release of LH upon challenge with naloxone on Day 10 of life; similar treatment of 1-day-old females resulted in a normal female-type response to the opioid antagonist. These results show that blockade of estrogen receptors in males during the "critical period" of sexual differentiation results in a female phenotypic response to naloxone. Therefore, estrogen receptors play a critical role in the sexual differentiation of the LH response to naloxone in neonatal male rats.

Animals↗
PubMed1988

Interrelation between end-systolic pressure-volume and pressure-wall thickness relations.

We predicted the shape of the end-systolic pressure-thickness relationship (ESPTR) by modeling the left ventricle as thick-walled sphere. To test the validity of the predicted relationships, we then measured the ESPTR over wide volume ranges in seven isolated blood-perfused canine hearts. Both simulation and experiments demonstrated that the ESPTR is curvilinear. However, within a physiological left ventricular systolic pressure range (80-150 mmHg), the ESPTR was described reasonably well by a straight line. Within that pressure range, changes in left ventricular contractile state, assessed by slope changes of the end-systolic pressure-volume relationship, were associated with almost parallel shifts in the ESPTR. In contrast, in a low pressure range (less than 80 mmHg), contractility changes were associated with slope changes of the ESPTR. We conclude that, in general, there are limitations in the application of ESPTR for assessing left ventricular contractility, but if the limitations are recognized and accounted for, then the ESPTR may be useful for assessing contractility changes in vivo.

Animals↗
PubMed1988

Impact of the Griffiths reforms of National Health Service management: the views of psychiatrists.

The Griffiths Report of 1983 recommended a number of reforms to the management of the National Health Service. These were strongly opposed in principle by the British Medical Association though some physicians saw them as potentially beneficial. This paper reports a survey of Psychiatrists in one English Region, whose responses suggest that although there remains little opposition in principle and respondents do see some beneficial effects, the new system tends to be seen in terms of its pragmatic disadvantages, with special reference to a perceived lack of managers' understanding of patients' needs.

Attitude of Health Personnel↗