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Biomedical subjects

R Schulz

Publications and source records attributed to R Schulz.

At least 541 records · Page 30Linked to original sources
PubMed1984

Receptor preference of dynorphin A fragments in the mouse vas deferens determined by different techniques.

The opioid receptor preference of dynorphin A fragments, particularly of dynorphin A-(1-8) (DYN 8), has been evaluated in the mouse vas deferens by means of cross-tolerance studies, by their sensitivity to naloxone antagonism and by the use of the irreversible narcotic antagonist beta-funaltrexamine. The tolerance studies revealed kappa receptor activity for the longer fragments and delta activity for the shorter fragments. DYN 8 displayed kappa as well as delta activity, whereas no interaction with mu receptors was observed. The naloxone sensitivity of dynorphin A and its fragments was low with the exception of DYN 8, that displayed an intermediate sensitivity. There was no indication that this intermediate value for DYN 8 was due to an interaction with mu receptors. This conclusion was strengthened in experiments using beta-funaltrexamine. The kappa and delta activity of DYN 8 does not explain the intermediate sensitivity to naloxone. It is proposed that DYN 8 may interact in the mouse vas deferens with a different opioid receptor than the classical mu, kappa- and delta-type.

Animals↗
PubMed1984

Consensus management in the British National Health Service: implications for the United States?

Most operational services within the reorganized British National Health Service are managed by local teams: medical specialist, general practitioner, nurse, administrator, and finance officer. Decision by consensus has worked well to integrate services in a complex and fiscally constrained system. As larger and more formal systems of health care emerge in the United States, the British experience may be relevant.

Administrative Personnel↗
PubMed1983

Elimination of the nucleus in preovulatory oocytes of the rainbow trout, Salmo gairdneri Richardson (Teleostei).

A process of elimination of the nucleus in oocytes of the rainbow trout displaying eight different stages is described. The phenomenon was observed only in stage III of sexual maturity. Initially, there is a slight shrinkage of the oocyte accompanied by the loss of yolk granules. This is followed by a cytoplasmatic protrusion into the ovarian lumen, which is covered by the follicular wall. Subsequently, the latter is ruptured and the nucleus migrates toward the opening. Finally, the nucleus leaves the follicle together with a portion of cytoplasm and the occasionally undergoes a breakdown into fragments in the ovarian lumen. The relevance of this mechanism in the process of preovulatory follicular atresia is discussed.

Animals↗
PubMed1983

Selective opiate tolerance in the guinea-pig ileum is not associated with selective dependence.

Opiate dependence attributable to specific types of opiate receptors was studied in the isolated guinea-pig ileum made tolerant/dependent in vivo to a specific narcotic agonist. Apparently, induction of dependence of mu-receptors was associated with dependence of kappa-receptors and vice versa. These investigations involved the use of the irreversible mu-receptor antagonist beta-funaltrexamine to provide preparations with functional kappa-receptors only. The documented cross-dependence between different opiate receptor types suggests a common system with which these opiate receptors interact.

Animals↗
PubMed1983

Multiple endorphins in neuronal hybrid cell lines.

Neuroblastoma x glioma hybrid cells (NG 108CC15) and tumors derived thereof were examined for dynorphin- and alpha-neoendorphin-like material. The techniques employed for analyses of opiate-like material were the isolated mouse vas deferens bioassay and gel chromatography and high pressure liquid chromatography in combination with radioimmunoassays. Dynorphin- and alpha-neoendorphin-like material was detected in both the hybrid cells and the corresponding tumors. Immunoreactive dynorphin and alpha-neoendorphin was also in NCB 20 hybrid cells and in tumors thereof assayed. In all samples investigated, the amounts of alpha-neoendorphin-like material was higher than that of dynorphin-like material. The results revealed considerable variability in the amount of dynorphin- and alpha-neoendorphin-activity between particular samples, suggesting the need for studies into the responsible mechanisms.

Animals↗
PubMed1983

A subclassification of multiple opiate receptors by means of selective tolerance development.

The chronic activation of opiate receptors results in the development of tolerance. On theoretical grounds, the appearance of cross-tolerance between different opioids should imply that these compounds exhibit an identical pattern on receptor activation. Tests with isolated tissue preparations, e.g. the guinea-pig ileum, made highly tolerant in vivo to the mu-agonist morphine proved that these were of almost unchanged sensitivity to different types of receptor agonists such as kappa-agonists. Thus, the ability to selectively induce tolerance on particular types of opiate receptors represents a reliable tool for the differentiation and characterization of multiple opiate receptors. Moreover, this technique facilitated the demonstration of subtypes of the already known opiate receptors.

Animals↗
PubMed1982

Opioid dependence and cross-dependence in the isolated guinea-pig ileum.

The development of opioid dependence and tolerance attributed to selective types of opiate receptors was studied in the isolated ileum of guinea pigs chronically exposed to specific opioids. These investigations were based on reports that in this preparation highly tolerant opiate receptors may coexist with opiate receptors of almost unchanged sensitivity. Thus, the ilea were set up in vitro and tested for tolerance and dependence. Apparently precipitation of the withdrawal contracture, indicating dependence, proved a more sensitive parameter than the phenomenon of tolerance. Maximal dependence was determined at rather low degrees of tolerance (5 to 10 fold). The intensity of the withdrawal contracture failed to increase as opiate tolerance did. Furthermore, the experiments failed to present evidence for the existence of selective dependence at specific opiate receptor types. These findings may suggest multiple adaptational mechanisms upon chronic activation of opiate receptors. One mechanism may be responsible for the development of dependence and a low degree of tolerance, whilst a further increase of tolerance may be associated with changes at the opiate binding site level.

Animals↗
PubMed1982

[Cytomegaly].

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Cross Infection↗
PubMed1982

Opiate receptor binding studies in the mouse vas deferens exhibiting tolerance without dependence.

The apparent lack of dependence in highly opiate-tolerant isolated mouse vas deferens may conflict with unitary theories postulating a common biochemical mechanism for both phenomena. Therefore, attention focused on binding sites of the opiate receptors which in this tissue are located presynaptically. Binding studies conducted with homogenate of highly tolerant vasa deferentia revealed no significant different results as compared to naive tissues. Further studies examined the effect of guanine nucleotide on opiate receptor interaction. Apparently, mu-, delta- and kappa-opiate receptors in the mouse vas deferens proved resistant to the regulatory action of guanine nucleotide in naive and tolerant tissues. From these experiments, it is concluded that the binding characteristics of opiate receptors in the mouse vas deferens do not change with chronic activation. In addition, the lack of an effect of guanine nucleotide on opiate binding leads to the suggestion that binding sites are not coupled to adenylate cyclase in this tissue. Taken together, these findings draw the attention to the coupling mechanism of opiate receptors in the mouse vas deferens which may play a key role in the adaptational mechanisms following chronic opiate exposure.

Animals↗
PubMed1982

Emotionality and aging: a theoretical and empirical analysis.

Much has been written about mood, emotionality, and affect in humans, but rarely has this topic been addressed from an adult developmental perspective. Indeed, the major theories on the determinants of human emotions have little to say about emotionality through middle and old age. Theories and data from several disciplines including psychology, sociology, gerontology, biology, and neurophysiology are integrated to propose answers to the following questions: (a) Do the intensity and duration of emotional experiences vary with age? (b) Do the aged show less day-to-day or within-day variability in emotional states? (c) Are particular types of emotional experiences more or less frequent among the aged? (d) Are there qualitative differences in the experience of specific emotional states among the aged? (e) Do the types of events that elicit emotional experience change with age?

Adaptation, Psychological↗
PubMed1982

[Investigations on the mutagenic and clastogenic activity of resorcin / Cytogenetic findings from different types of human cells (author's transl)].

The suspected clastogenic effect of m-dihydroxybenzene (resorcin), a phenol derivate, was investigated by analyzing 3 different types of human cells. 1. Lymphocyte cultures from blood of healthy blood donors with normal karyotype (46,XY). 2. Lymphocyte cultures from patients with a proved chromosome abnormality (trisomy 21, karyotype: 47, +21). 3. Cultures of amniotic cells with normal karyotype (46, XX and 46, XY). In all three cell systems resorcin induces secondary chromosome aberrations. The amount of cells with aberrations increases with the concentration of the substance and duration of action. The three cell systems tested showed a different sensitivity to resorcin. Lymphocytes with trisomy 21 were more sensitive than the same cell type with a normal karyotype. Both types of lymphocytes were less sensitive to resorcin than amniotic cells. The types of structural chromosome aberrations observed in these investigations as well as the concentration of the test substance, which had to be added to induce a clastogenic effect, demonstrated that resorcin has to be regarded as a weak mutagenic substance.

Amniotic Fluid↗