Angiotensin-converting enzyme and other peptidolytic enzymes in human semen and relations to its spermatologic parameters.

Angiotensin-converting enzyme (ACE) and other enzymes of the renin-angiotensin system (RAS) occur in human semen in high activities. In contrast to bull ejaculates, not all zinc-dependent metallopeptidases are found to be in close correlation to the microscopically determined semen parameters; such a relationship was established only partly for the ACE. On the other hand, the RAS-dependent spermatozoa-bound enzymes, inclusive ACE, uniformly show negative correlations to the spermatologic parameters of human semen. These results, for the first time, point to different functions of the sperm-cell-bound (testicular) and of the seminal plasma (pulmonary) ACE activities.

Occurrence and potential importance of angiotensin-converting enzyme in semen of boars.

The activities of angiotensin-converting enzyme (ACE) and leucinaminopeptidase (LAP) are positively correlated with corresponding concentrations of sperm cells in semen of boars kept under normal conditions. The spermatozoa bound ACE activity, in general, does not reflect differences in the quality of semen (bull and boars). On the other hand, the ACE activity directly bound on the sperm cells is significantly elevated, if 'exogenic noxes' (by feeding or keeping) influence the fertility of boars in a drastic manner. These results are discussed with regard to the differential diagnostic importance for estimating the semen quality and to the causal relations between increased enzyme binding and injury of sperm cells.

Occurrence and potential importance of selected peptidases in bull ejaculates.

The zinc containing peptidases angiotensin-converting enzyme (ACE), neutral metalloendopeptidase (NEP), and leucine aminopeptidase (LAP) occur in bull ejaculates in high activities. These enzyme activities are in close correlation with some routineously determined semen parameters. These ejaculat parameters are used for quality classification and selection of ejaculates and are according to long term experience in good correlation to the male fertility. Semen quality related correlations could not be found for the dipeptidyl aminopeptidase (DPIV) and the aminopeptidase A (APA). Origin and possible function of the zinc containing peptidases in the semen are examined and discussed.

[Possible involvement of the renin-angiotensin system in reproduction. II. Occurrence and role in the female reproductive tract]. / Zur möglichen Mitbeteiligung des Renin- Angiotensin-Systems am Fortpflanzungsgeschehen. II. Vorkommen und Rolle im weiblichen Reproduktionstrakt.

Biochemical and immunological studies of the last years reveal the existence of an "ovarian renin-angiotensin system (RAS)". Despite of the low angiotensin-conterting enzyme (ACE) activity in the ovary the follicular fluid is rich in angiotensin II (AII). The detection of AII receptors on cells within maturating follicles proves them as AII targets. Therefore, it is supposed that AII may be involved in the regulation of fundamental processes of follicle maturation and/or corpus luteum formation. Further interesting findings are the high concentration of prorenin in the follicle fluid of women causing an increase of the prorenin blood plasma level at time of ovulation, and a second increase of the blood prorenin concentration in the middle of the luteal phase. With respect to the ACE activity in the ejaculate it is imaginable that the smooth muscle tonus of the uterus and the oviduct could be affected by local generation von AII and/or degradation of bradykinin and thus the transit of the semen may be facilitated. Further systematic research is necessary to bring more light into the physiological context and to replace hypothetical interpretations of the findings by exact knowledge.

[Possible involvement of the renin-angiotensin system in reproduction. III. Occurrence and role in pregnancy]. / Zur möglichen Mitbeteiligung des Renin-Angiotensin-Systems am Fortpflanzungsgeschehen. III. Vorkommen und Rolle bei der Gravidität.

To clarify a possible participation of the renin-angiotensin-system (RAS) in physiological processes of pregnancy, findings are listed about occurrence and variations of RAS components in uterus, placenta, amniotic fluid, fetal membranes, fetus and serum. There exist complete and independent RAS in the respective organs and tissues. During pregnancy concentrations and/or activities of the components change, but in different ways and non-uniforming. The information now available does not yet allow a definite view on the role of RAS during pregnancy and on the correlations to estrogens, progesterone, chorionic gonadotropin, prostaglandins etc. Supposedly RAS may be involved to a high degree in the local regulation of blood flow and the maintenance of fetal vascular homeostasis. Furthermore, there are relations between fetoplacental components of RAS and pregnancy-induced hypertension. Further investigations are necessary. They are expected to offer therapeutic possibilities for influencing pathological processes in which RAS plays a role.

[Possible involvement of the renin-angiotensin system in reproduction. I. Occurrence and role in the male reproductive tract]. / Zur möglichen Mitbeteiligung des Renin-Angiotensin-Systems am Fortpflanzungsgeschehen. I. Vorkommen und Rolle im männlichen Reproduktionstrakt.

With regard to the blood pressure the regulative function of the renin-angiotensin-system (RAS) is well known. Knowledge of the last years is that components of the RAS are available also in organs and excrets of the male reproductive tract. So, the angiotensin-converting-enzyme (ACE) - a key enzyme of the RAS - exists in the testes in an extraordinary high activity exceeding those of the lung tissue. In the ejaculate this so-called "testicular ACE" is associated with sperms, whereas the seminal plasma contains the higher molecular "pulmonary ACE". Because both isoenzymes posses the same catalytic effectiveness, the occurrence of adequate substrates (angiotensin I, bradykinin) and degrading products as effectors (angiotensin II), respectively, is of high importance for the valuation of the physiological relevance of the RAS in the process of fertility. Up to date, the knowledge is still insufficient, partly even contradictory. Therefore at present the regulative function(s) of the RAS in the male reproductive tract can only be expressed as postulates.

[The effect of methionine enkephalin, leucine enkephalin and the hexapeptide, dalargin on the morphology of cultured neurons]. / Wirkungen der Opioidpeptide Met5- und Leu5-Enkephalin sowie des Hexapeptids Dalargin auf die Morphologie des Nervengewebes unter Kulturbedingungen.

Cell cultures derived from brain, ganglion trigeminale or retina of 5- and 9-day-old chick embryos and from brain stem or hippocampus of 16-18 day-old fetal rats were treated with Met5-, Leu5-enkephalin, or Dalargin--a synthetic hexapeptide structurally related to Leu5-enkephalin--and evaluated morphologically. The treatment of the nervous tissue cultures with the peptides markedly affected their growth pattern. Aggregates of glial and neuronal cells were surrounded by flat cells forming monolayer network structures. In cultures of brain from 5 day-old chick embryos the proliferation of the cells was significantly stimulated. No growth of neurites was observed. It is discussed that the tested Enkephalins and in the same way the Dalargin may play an important role in the early neuronal development. Their activity in phase 0 and phase 1 of the life history of nerve cells indicates aspects of temporary peptide influences. Excess of glial cells caused by the tested peptides did not enhance neuronal differentiation. The transdifferentiation of developing receptor cells into ependymal cells during the adaptation process in retina cultures as a special effect of Dalargin is discussed. The present findings suggest that the influence of (opioid) peptides in vitro may be detected morphologically and that nervous tissue culture is a valuable tool for differentiating neuronotrophic neurite-promoting and neurotoxic drug effects.

Influences of the chemical structure on the activity of new inhibitory compounds of the angiotensin-converting enzyme.

The ACE inhibitory activity of some perimidines, chinazolinones and amidinohydrazones is described. Relations were found between the chemical structure and the inhibitory activity on the ACE.

[Effect of derivatives of substance P dipeptide on nerve fiber growth in tissue culture]. / Wirkung von Derivaten des Substanz P-Dipeptids auf das Nervenfaserwachstum in der Gewebekultur.

Explants and cells from the peripheral (PNS) and central nervous system (CNS) were cultivated in MAXIMOW chambers. The following four derivatives of Substances P (SP) dipeptide were tested for their effects in concentrations between 10(-4) and 10(-8) mol/l: Lys-Pro X 2HBr, Lys(Z)-Pro X HCl, Lys[Z(NO2)]-Pro X HCl and cyclo(Lys-Pro) X HCl. The results suggest that SP and SP derivatives may modulate nerve fibre outgrowth in vitro. In ganglion trigeminale explants Lys(Z)-Pro X HCl stimulated the growth of nerve fibres. The explant covered areas increased significantly. In telencephalon explants and cell cultures the tested derivatives did not essentially promote neurite outgrowth. In retinal cell cultures incubated with cyclo(Lys-Pro) X HCl and Lys[Z(NO2)]-Pro X HCl the neurite outgrowth index was stimulated in a different way. The neurite length was affected and stimulated in the presence of Lys(Z)-Pro X HCl and cyclo(Lys-Pro) X HCl. Both for survival and differentiation PNS neurons depend on specific biofactors. In sensory ganglia explants SP and especially SP derivatives were shown to improve neuronal survival provided that serum or embryonic extract was simultaneously present in the medium. Even if the dipeptides need other biofactors for their full function the may be discussed as neuronotrophic factors because they ensure survival and general growth capability of the responsive neuroblasts.

Stimulation of wound healing, using brain extract with fibroblast growth factor (FGF) activity. III. Electron microscopy, autoradiography, and ultrastructural autoradiography of granulation tissue.

A bovine brain fraction with FGF activity (fibroblast growth factor) increased the formation of granulation tissue of rats in an experimental wound healing model. It was characterised by intensified formation of new capillaries, stimulation of the synthesis function of fibroblasts and myofibroblasts, and proliferation of freshly developed granulation tissue. The results obtained from light microscopy and autoradiographic electron microscopy with 3H-thymidine suggested significant increase in the labelling of activated, undifferentiated endothelial cells in vascular sprouts and of differentiated endothelial cells in developed capillaries. FGF S3 appeared to speed up the differentiation of freshly formed endothelial cells. Also labelled were pericytes and other fibroblastoid cells, undifferentiated mesenchymal cells, juvenile undifferentiated fibroblasts, mature fibroblasts, myofibroblasts, and macrophages. Pericytes are presumed to be preferential precursors of myofibroblasts, on account of their occurrence in time and similar ultrastructural parameters. Close neighbourhood of lymphocytes and labelled fibroblasts gave rise to the assumption of specific effects, such as stimulation by lymphokines.

[Substance P inhibition of the activity of the angiotensin-converting enzyme from human blood serum]. / Podavlenie veshchestvom "P" aktivnosti angiotenzinprevrashchaiushchego fermenta iz syvorotki krovi cheloveka.

Substance "P" (SP) and its derivatives inhibited activity of angiotensin-converting enzyme (ACE) in human blood serum, I50 for SP was 31 microM. The same results were obtained for N-terminal fragments of the SP molecule: Arg-Pro-Lys-Pro and Lys-Pro. The C-terminal heptapeptide and the dipeptide Arg-Pro negligibly inhibited ACE activity. A possible significance of the interaction between SP and ACE in the regulation of the microhemodynamics is discussed.

Stimulation of wound healing, using brain extract with fibroblast growth factor (FGF) activity. I. Quantitative and biochemical studies into formation of granulation tissue.

In rats with polyvinyl rings implanted under the dorsal skin, the formation of granulation tissue was found to be stimulated by application of brain extract with fibroblast growth factor (FGF) S3 activity which had been obtained from cattle. This stimulating effect on wound healing proved to depend on doses and was detectable in rats aged two and six months on the third and seventh postoperative days. The desired action could be induced only by repetitive administration of FGF S3 or by coupling of the latter to SYSpur-derm, a synthetic dermatoplastic material. More fractions with potential action upon formation of granulation tissue proved to be obtainable from further biochemical separation of FGF S3. One of such fractions was successfully concentrated to a potentiality by which one tenth of the normal dose yielded the same effect as the full dose. Hexosamine and hydroxyproline levels were measured, at the same time, and found to stimulate fibroblasts. The findings are discussed.

Stimulation of wound healing, using brain extract with fibroblast growth factor (FGF) activity. II. Histological and morphometric examination of cells and capillaries.

Reported in this paper are studies by which evidence was produced to increased formation of granulation tissue in rats, aged two and six months, seven days after repeated localised administration of brain extract from cattle with FGF activity (fibroblast growth factor). Such increased formation of granulation tissue was attributable to the formation in the same granulation tissue of larger amounts of capillaries, which actually provided conditions for better blood supply. The above increase was associated with stimulation of the synthetic function of fibroblasts and myofibroblasts in the granulation tissue. Comprehensive morphometric tests, including differential counting, appeared to show that additional effects had to be assumed, in particular on macrophages and lymphocytes. Such increase in angiogenesis seemed to suggest that in the in vivo model studied FGF proved to be, first of all, a factor of angiogenesis rather than a factor of fibroblast growth. The above results, as obtained from rats which differed in age, exhibited a certain variation in response to FGF. This seems to underline the importance of age-dependent examination also in the context of pharmacological studies.

Is dipyridamole an angiogenic agent?

Dipyridamole, a potent inhibitor of the nucleoside transport into cells, has recently been reported to stimulate the proliferation of capillary endothelial cells in the heart and skeletal muscle of rats following long-term treatment. We tested this drug on cultured calf aortic endothelial cells and obtained no evidence that dipyridamole is able to stimulate directly the proliferation and migration of these cells. By using the chorioallantoic membrane model we observed that the pharmaceutical preparation Curantyl induces vascular responses almost regularly. This effect, however, was found to be dependent on the high concentration of hydrogen ions in this preparation and could be prevented by increasing the pH value. A direct angiogenic effect of dipyridamole could not be demonstrated on the CAM.

[The effect of substance P (SP) and SP partial sequences on nerve fiber growth in tissue culture]. / Uber die Wirkung von Substanz P (SP) und SP-Teilsequenzen auf das Nervenfaserwachstum in der Gewebekultur.

Explants of the ganglion trigeminale (PNS) and of the telencephalon (CNS) from chick embryos were cultivated in MAXIMOW chambers in semisynthetic media in the presence of dipeptide fragments (Lys(Z)-Pro . HCl, Lys-Pro-2HBr, Arg-Pro-2HCl) and the heptapeptide (SP5-11) of substance P as well as the complete substance P (SP1-11). 1. Histological examination of the dipeptide-treated CNS explants indicates that the structure of outgrowth in vitro is changed. Fascicel were observed. A stimulation of nerve fibre extension did not take place. 2.1. In dipeptide-treated PNS cultures the index of areas covered by the explants increased. 2.2. The index of nerve fibre growth increased significantly. The stimulation was caused in multiplication of fibres. Only Lys(Z)-Pro . HCl presents a prolongation of neurites. 2.3. SP5-11 effects in no case the growth of nerve fibres. SP1-11 stimulated significantly the fibre regeneration. 3. The possible role of SP1-11 with different effects under in vitro conditions is discussed. Only the N-terminal dipeptides stimulate the growth of nerve fibres. The C-terminal SP5-11 is without effect. Finally it is stated that the best results in neuritic enlargement and neurogenesis can only be obtained by cultivation with SP1-11.