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Biomedical subjects

M Pawlikowski

Publications and source records attributed to M Pawlikowski.

At least 19 recordsLinked to original sources
PubMed1992

Angiotensin II stimulation of the rat pituitary tumoral cell proliferation in vitro.

The effect of angiotensin II (AT II) on proliferation of rat pituitary tumoral cells was investigated in vitro. The tumoral cells were isolated from the prolactin-secreting pituitary tumors induced by stilboestrol implantation. The incorporation of [3H]-thymidine into DNA was used as an index of cell proliferation. It was found that AT II significantly enhanced the [3H]-thymidine incorporation into pituitary tumoral cells in the concentrations of 10(-10) and 10(-8) M. The stimulatory effect disappeared at the concentration of 10(-6) M. The possible involvement of pituitary renin-angiotensin system in pituitary tumorigenesis was discussed.

Angiotensin II↗
PubMed1992

Thyroliberin (TRH) increases thymus cell proliferation in rats.

The effects of thyroliberin (TRH), a TRH-like tripeptide colon mitosis inhibitor (CMI), a somatostatin analog SMS 201-995 and metoclopramide (dopamine receptor antagonist enhancing prolactin secretion) on rat thymus cell proliferation were investigated. The incorporation of bromodeoxyuridine (BrDU) into thymic cell nuclei was used as an index of the proliferation. It was found that TRH, but not other compounds investigated herein, increased the thymus cell proliferation 12 hours after the injection.

Amino Acid Sequence↗
PubMed1992

Effects of somatostatin on inositol-1,4,5-trisphosphate content in mouse spleen lymphocytes.

1. The effects of somatostatin-14 (SS) and diazepam in vitro on the content of inositol-1,4,5-trisphosphate (IP3) in mouse spleen lymphocytes were investigated. 2. It was found that the exposure of mouse spleen lymphocytes in vitro to SS sharply diminished their IP3 level. 3. Diazepam had no effect on lymphocytes IP3 content. 4. The inhibition of phosphatydyloinositol (PI) breakdown was suggested as one of the mechanisms of the physiological SS action.

Animals↗
PubMed1992

Food restriction enhances melatonin effects on the pituitary-gonadal axis in female rats.

The effects of melatonin (25 micrograms s.c. daily in the late afternoon for 10 days) on the ovarian morphometry and the gonadotropin secretion were investigated in food-restricted rats and rats fed ad libitum. In food-restricted rats melatonin produced the significant decrease of the surface area of the ovary and of zona granulosa. Moreover, melatonin treatment of food-restricted rats resulted in significant diminishment of the relative areas of Graafian follicles and zona granulosa estimated in relation to the ovary cross-sectional surface area. On the other hand, melatonin did not produce significant alterations of the morphometric indices of the ovary in rats fed ad libitum. Melatonin administration was found to inhibit the effects of gonadoliberin on gonadotropin release in food-restricted but not in normally-fed rats. These findings suggest that food restriction sensitizes the pituitary-ovarian axis to antigonadotropic melatonin action.

Animals↗
PubMed1992

[Mineralization of heart valves].

Mineralization (calcification) of heart valves (mitral, aortic and aortic bioprosthesis) have been analyzed using; histology, x-ray diffraction, infrared spectroscopy, scanning microscopy, atomic absorption and electron microprobe. Obtained results showed the presence of two type of mineralization. First type is represented by grains composed of hydroxyapatite containing admixture of carbonates. This mineralization is seen macroscopically. Second type of mineralization is possible to determine only using chemical methods. It is represented by biological structures containing amount of Ca, P and other elements higher then normal heart valves. This second type of the mineralization conducts to the changes of physical features of the tissue. Both types of calcification develops because of the defects of atomic structure of biological components of heart valves (mainly collagen). These defects show the presence of free atomic bindings i.e. electric potential. Because of this, they are able to react with surrounding free joints, starting calcification. Defects of biological structures of heart valves are the results of infections, mechanical destruction of the valves etc. Calcification may be stopped on different stages of its development: or as secret calcification or may pass to the stage seen as apatite grains.

Adult↗
PubMed1992

Stimulation of rat pituitary tumoral cell proliferation in vitro by tetra- and pentagastrin.

The effects of the active gastrin fragments, penta- and tetragastrin on the incorporation of tritiated thymidine into the rat pituitary tumoral cells were investigated in vitro. The significant stimulation of 3H-thymidine incorporation was observed as an effect of the investigated substances. The putative role of gastrin as an autocrine growth factor active in pituitary tumorigenesis was discussed.

Animals↗
PubMed1992

Chronic metoclopramide treatment stimulates T lymphocyte proliferation in the spleen but not in the thymus.

The effect of chronic metoclopramide administration (for 10 days at a daily dose of 5 mg/kg body weight subcutaneously) on cell proliferation in spleen and in thymus was investigated. Cell proliferation was evaluated by the stathmokinetic method with the use of vincristine. It was found that metoclopramide administration results in a statistically significant increase in the value of the mean mitotic activity rate index (MMAR) of splenocytes in the areas around arteries. At the same time no statistically significant changes were demonstrated in the MMAR index values obtained for splenocytes present in the germinal centers of the spleen. No significant changes in the MMAR index could also be found for thymocytes.

Animals↗
PubMed1992

Effects of omeprazole on the number of immunoreactive gastrin- and somatostatin-cells in the rat gastric mucosa.

The effects of omeprazole--an inhibitor of gastric acid secretion--on gastrin (G)- and somatostatin (D)-cell density in the gastric antral mucosa epithelium in rats were examined, following a 5-day treatment. It was found that omeprazole increased the density of G-cells, whereas it decreased the density of D-cells. That effect was probably independent of hypergastrinaemia, since it could not be blocked by a simultaneous treatment with proglumide--a gastrin receptor blocker. It is concluded that the observed phenomenon is a direct result of a lower gastric acidity, as a consequence of omeprazole treatment.

Animals↗
PubMed1992

[Mineral changes occurring with age in the intervertebral disks of L4-L5 vertebrae].

The results of mineralogical examination of 26 L4-L5 intervertebral discs taken from cadavers has been presented. Radiology did not reveal marked osteoarthritic changes at this level. The age of the individuals at the fatal accident ranged from 4 to 87 years (mean 41.2). -- Scanning microscopy, atom absorbtion spectroscopy and roentgen microscopy was used in the examination. Two age related phenomena were discovered; demineralisation of the nucleus pulposus and mineralisation of the anulus fibrosus. Two types of mineralisation were found; the microscopic one visible as granules of different shape and size consisting of crystalline hydroxyapatite aggregates and the one detectable exclusively by sensitive chemical methods as an increase of Ca and P content and disturbance of the remaining elements content in biological structures.

Adolescent↗
PubMed1992

Effect of mesulergine on prolactin secretion and dopamine D2 receptors-adaptive changes in diethylstilbestrol-induced hyperplasia of the rat anterior pituitary.

Mesulergine (N,N-dimethylsulphamide-N'-1,6-dimethyl-ergoline-8 alpha-yl) is an active semisynthetic ergot derivative with lower antiprolactin potency compared with bromocriptine or pergolide. Since no data are yet available on the effects of mesulergine on pituitary dopamine receptors, the present study has been designated to elucidate the influence of this drug on prolactin secretion in vivo and in vitro and 3H-spiperone binding by the anterior pituitary gland in female Wistar rats with experimentally induced hyperprolactinemia. Three weeks after bilateral ovariectomy and subcutaneous implantation of silastic tubes, containing 10 mg of diethylstilbestrol, a dramatic rise in serum prolactin levels was observed (1.67 +/- 0.23 vs. 80.82 +/- 3.80 ng/ml; P less than 0.001). Mesulergine attenuated the stimulatory effect of diethylstilbestrol on serum prolactin level in a time- and dose-dependent fashion. At concentration range between 10(-5) and 10(-7) M it also inhibited prolactin secretion from cultured rat pituitary cells to the medium during 180 min incubation in a dose-dependent manner. Scatchard analyses performed on the in vitro 3H-spiperone binding kinetics in a dispersed anterior pituitary cell culture, prepared from the pituitaries from rats treated for four weeks with diethylstilbestrol, showed that chronic mesulergine treatment (in dose of 3.0 mg/kg injected s.c. for 10 days) induced a significant decrease in the number of dopamine D2-binding sites (Bmax 28.00 +/- 4.20 vs. 42.80 +/- 4.76 fmol/10(6) cells; P less than 0.01) without any changes in D2-receptor affinity. Our results suggested that antiprolactin activity of mesulergine in vivo and in vitro is probably associated with agonistic effect of this drug on D2-dopamine receptors.

Animals↗
PubMed1991

Inhibitory effect of thyrotropin releasing hormone on spontaneous proliferation of mouse spleen lymphocytes in vitro.

The effects of thyrotropin releasing hormone (TRH) and of TRH-like tripeptide pGlu-His-Gly-OH (colon mitosis inhibitor, CMI) on spontaneous proliferation of murine splenocytes were investigated in vitro. The 3H-thymidine incorporation into splenocyte DNA was used as an index of proliferation. It was found that TRH suppressed the proliferation of splenocytes. In contrast, CMI was ineffective by itself but used together with TRH blocked the effect of the latter.

Amino Acid Sequence↗
PubMed1991

Effects of somatostatin-14 and its analogs on the (Ca,Mg)ATPase in the rat anterior pituitary.

The effects of somatostatin-14 and its biologically active analogs, RC-160 and SMS 201-995, on (Ca,Mg)ATPase activity in vitro were studied in homogenates of anterior pituitary cells. It was found that somatostatin inhibited the (Ca,Mg)ATPase activity in the anterior pituitary and somatostatin analogs exerted slight biphasic effects on the calcium pump activity. The effects of specific brain (Ca,Mg)ATPase inhibitors, VOSO4 and LaCl3, were also studied in vitro. Neither VOSO4 nor LaCl3 enhance the inhibition of calcium pump activity caused by somatostatin. It is suggested that somatostatin may mediate its action in pituitary cells, among others, by the regulation of (Ca,Mg)ATPase activity.

Animals↗
PubMed1991

Inhibitory effect of porphyrins on the proliferation of mouse spleen lymphocytes in vitro.

The influence of various porphyrins (deuteroporphyrin IX, mesoporphyrin IX, protoporphyrin IX, hematoporphyrin) and two related compounds (hemin, biliverdin) on the spontaneous proliferation of mouse spleen lymphocytes has been estimated in vitro by the 3H-thymidine uptake assay. It has been found that porphyrins (endogenous ligands for the mitochondrial benzodiazepine receptor) produce a concentration-dependent inhibition of 3H-thymidine incorporation into the DNA of these cells. Metalloporphyrin-hemin has been observed to evoke a weak inhibitory effect, in a high concentration (10(-4)M), whereas biliverdin, a porphyrins degradation product, was inactive in the same experimental conditions. Those findings indicate that endogenous porphyrins, presumably acting through the mitochondrial benzodiazepine receptor, could regulate the proliferation of mouse spleen lymphocytes in vitro.

Animals↗
PubMed1991

The effect of nerve growth factor on DNA synthesis, cyclic AMP and cyclic GMP accumulation by mouse spleen lymphocytes.

Nerve growth factor (NGF), a trophic neuropeptide, is known to stimulate development, and to be important in the maintenance and survival of sympathetic and sensory neurons. Considering the presence of specific receptors on the surface of spleen cells, the effect of 2.5s nerve growth factor on 3H-thymidine uptake, cAMP and cGMP accumulation in mouse spleen lymphocytes has been studied. It was found that NGF added in vitro at the concentrations between 4 x 10(-7) and 4 x 10(-8) M significantly inhibited the incorporation of 3H-thymidine into lymphocytes DNA and increased cAMP levels in a dose-dependent manner but had no effect on cGMP levels. The maximal stimulation of cAMP synthesis occurred between 5 and 30 min after the NGF addition to the culture medium. When NGF was administered in vivo a significant dose-dependent inhibition of the lymphocytes proliferation was observed. These results indicate that an early increase of cAMP concentration is responsible for the antiproliferative action of NGF on mouse spleen lymphocytes and suggest that NGF could play an important role in the regulation of immune system function.

Animals↗
PubMed1991

Effect of omeprazole-induced hypergastrinaemia on the proliferation of colonic mucosal epithelial cells in the rat.

In the present study we have investigated the effects of proglumide (PRO) and somatostatin analog (SMS 201-995) on the mitotic activity of colonic mucosa in rats under basal conditions and after omeprazole (OM). The stathmokinetic method was used. Proglumide and OM were administered for 5 days, twice daily, SMS 201-995 on the 5th day of the experiment only, also twice daily. It was found that: 1) OM enhanced the proliferation of colonic mucosa, as well as increased serum gastrin, when compared to controls, 2) OM and PRO, when applied jointly, decreased the mitotic activity of the colonic epithelium, 3) PRO alone increased the colonic cell proliferation.

Analysis of Variance↗
PubMed1991

Influence of pineal indoleamines on the mitotic activity of gastric and colonic mucosa epithelial cells in the rat: interaction with omeprazole.

We have investigated the effects of melatonin (Mel) and N-acetylserotonin (NAc-5HT) on the mitotic activity of gastric and colonic mucosa in adult male rats under basal conditions and after an administration of omeprazole (OM) (H+,K(+)-ATPase inhibitor). The metaphase-arrest technique was applied in the study. Additionally, serum gastrin levels were measured by RIA method in the OM-treated group and in respective polyethyleneglycol (PEG)-administered controls. We have found that: 1) OM-treatment increased serum gastrin levels in rats; 2) OM enhanced the mitotic activity of the colonic mucosa cells, although, unexpectedly, it did not exert such an effect on the gastric mucosa cells; 3) Mel suppressed the OM-induced increase of the colonic epithelium cell proliferation, while NAc-5HT failed to reveal that action: 4) NAc-5HT decreased the proliferation of gastric mucosa epithelial cells. The value of the mean mitotic activity rate (MMAR) of gastric mucosa after Mel-treatment also decreased, but that change was not statistically significant. The obtained data are in compliance with previous results from our laboratory concerning the inhibitory effect of pineal indoleamines on the jejunal epithelium mitotic activity. The stimulatory effect of OM on the proliferation of colonic epithelium is probably mediated by OM-induced hypergastrinaemia. The possibility of Mel interaction with intestinal gastrin receptors (a structural similarity occurs between Mel and benzotript, a specific gastrin receptor antagonist), as well as of the opposite effects of Mel and gastrin on intracellular cAMP content in the gut, are considered in the discussion of results.

Analysis of Variance↗