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Biomedical subjects

K Winczyk

Publications and source records attributed to K Winczyk.

16 recordsLinked to original sources
PubMed2006

Melatonin in humans.

Melatonin, the hormone of the pineal gland, received a great deal of attention in the last decade because of its availability as over-the-counter drug or food supplement in some countries and suggested role in many vital physiological processes. Melatonin secretion is not restricted to mammals but is also produced in nonmammalian vertebrates, in some invertebrates, and in many plants, with the same molecular structure. The synthesis of melatonin is strictly controlled by lighting conditions and shows a clear circadian rhythm with low values during the daytime and significant increase at night. In this survey the basic data on melatonin significance in human physiology and in pathological processes as well as its possible therapeutic significance are reviewed and discussed.

Humans↗
PubMed2001

Melatonin and RZR/ROR receptor ligand CGP 52608 induce apoptosis in the murine colonic cancer.

The effects of melatonin and the thiazolinidinedione derivative CGP 52608 on apoptosis of Colon 38 cancer cells were investigated. Male mice were implanted subcutaneously with a suspension of Colon 38 cells. Ten days after induction of tumors, the animals were treated with melatonin or CGP 52608. Both substances were given in subcutaneous injections in daily doses of 10 or 100 microg in the evening for 6 days. The control group received solvent. The apoptotic cells were visualized in paraffin sections by means of the transferase-mediated dUTPnick end-labeling method. Both treatments increased significantly and to the same degree the number of apoptotic cells in tumors. This finding confirms our earlier observation that melatonin exerts a pro-apoptotic effect on murine colonic cancer cells. Moreover, because CGP 52608 is a ligand of RZR/ROR receptors and the latter are considered by some investigators as nuclear binding sites for melatonin, our data suggest the involvement of these receptors in the pro-apoptotic effect of melatonin.

Animals↗
PubMed2000

Time of day-dependent effects of thyroliberin and thyrotropin on thymocyte proliferation in rats.

Our earlier studies have shown that thyroliberin (TRH) as well as thyrotropin (TSH) enhanced thymus cell proliferation. The aim of the present study was to investigate whether the effects of TRH and TSH on thymocyte proliferation depend on time of day. A single subcutaneous injection of TRH (25 microgram/animal) or TSH (3 IU/animal) was made at 9:00 h (1 h after light onset) or at 18:00 h (10 h after light onset) in 3-month-old male Wistar rats. The animals were killed 24 h later. The proliferation of thymocytes was assessed by incorporation of bromodeoxyuridine into cell nuclei. Thymocyte proliferation was significantly increased by TSH administration at 9:00 h, whereas treatment given at 18:00 h was ineffective. TRH enhanced the proliferation when injected at 9:00 h, but had an inhibitory effect when administered at 18:00 h. These data indicate that the effects of TRH and TSH on thymocyte proliferation are dependent on time of day.

Animals↗
PubMed1998

Differential effects of somatostatin and its analog on protein tyrosine kinases activity in the rat pituitary and the murine colonic tumors.

The effects of the native somatostatin-14 (SST-14) and of its analog octreotide (OCT) on the activity of protein tyrosine kinases (PTK) in the normal rat anterior pituitary gland, diethylstilbestrol (DES)-induced rat pituitary tumor and murine colonic cancer Colon 38 were studied in vitro. PTK activity was estimated in tissue homogenates using gamma-[32P]ATP and poly (Glu80, Tyr20) as a substrate. It was found that both SST-14 and OCT suppressed the PTK activity in all examined tissues. The suppressive effect was more pronounced in DES-induced pituitary tumor than in normal anterior pituitary gland, and in the former, OCT was more effective than SST-14. In contrast, SST-14 stronger suppressed PTK activity in colonic cancer than OCT. We hypothesize that SST-14 acts on PTK activity in colonic cancer mainly via SSTR-1 subtype of somatostatin receptors.

Animals↗
PubMed1997

Differential effects of somatostatin analogues on proliferation of murine colonic cancer cells in vitro.

The effects of somatostatin analogues octreotide (SMS 201-995), ASS-51 and ASS-52 on [3H]-thymidine incorporation into DNA of the murine colon 38 cancer cells in vitro were investigated. It was found that SMS 201-995 and ASS-51 inhibited the tritiated thymidine incorporation in a dose-dependent manner. In contrast, analogue ASS-52 in spite of a very similar structure to ASS-51, which differed from the latter only by one CH2OH group, was devoid of remarkable antiproliferative activity. These results indicate that slight modification of the molecule of somatostatin analogues may deeply influence their antiproliferative activity.

Amino Acid Sequence↗
PubMed1994

Interleukin-1 beta stimulates cell proliferation in the intermediate lobe of the rat pituitary gland.

Interleukin-1 (IL-1) is a multifunctional monokine which possesses an impressive array of diverse actions relating to the function of the immune system. IL-1 is present and formed locally in the brain as demonstrated by biochemical and immunocytochemical methods. Various immunomodulatory and neuroendocrine effects of IL-1 have been reported, including induction of several morphological changes in the endocrine cells of experimental animals and humans. IL-1 is present in two molecular forms (IL-1 alpha and IL-1 beta) that activate specific receptors for IL-1. In the present study we investigated the possible effect of recombinant human IL-1 alpha and IL-1 beta and recently cloned anti-human IL-1 receptor antibody (M10) on cell proliferation in the anterior and the intermediate lobe of the pituitary gland of the rat. In vivo labelling with bromodeoxyuridine (BrdU) and immunocytochemical staining with anti-BrdU monoclonal antibody were used as a sensitive index of cell proliferation. IL-1 beta was found to stimulate dose-dependently (0.1-10 micrograms/kg body weight) incorporation of BrdU into pituitary intermediate cell nuclei, and positive correlation between the tested doses of IL-1 beta and BrdU-labelling index was noted (r = 0.89; P < 0.01). This IL-1 beta-induced stimulation of pituitary pars intermedia cell proliferation was receptor specific, since stimulation was blocked by anti-IL-1 receptor antibody. On the other hand, recombinant human IL-1 alpha did not affect BrdU incorporation and the proliferation of pituitary pars intermedia cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effects of new somatostatin analogs on the cell proliferation of colonic crypts and colonic cancers in rats.

The antiproliferative activity of two new somatostatin (SS) analogs: ASS-51 and ASS-52 have been tested in this study. We assessed their ability to inhibit the DNA synthesis in normal colon crypt cells and in the cells of chemically (dimethylhydrazine)-induced colon cancer in the rats. The incorporation of bromodeoxyuridine (BrDU) into appropriate cell nuclei was used as an index of DNA synthesis. It was found that: 1) Only ASS-51 significantly decreases the colon crypt cell proliferation in the rat when compared to controls. Since both analogs were previously shown to inhibit GH release, these data indicate that the antiproliferogenic effect of ASS-51 is independent of the inhibition of GH release. 2) Both examined analogs did not significantly effect the BrDU incorporation into cell nuclei of chemically-induced colon cancer.

Adenocarcinoma↗
PubMed1993

Failure of tripeptide colon mitosis inhibitor to suppress the cell proliferation of dimethylhydrazine-induced colonic cancers in rats.

The effects of tripeptide colon mitosis inhibitor (CMI, pGlu-His-Gly-OH) on the proliferation of tumoral cells of dimethylhydrazine (DMH)-induced colonic cancers in rats were studied. Additionally, the effects of CMI on hyperplastic colonic crypts in DMH-treated rats and on normal colonic crypts in carcinogen-untreated rats were estimated. As an index of the cell proliferation the incorporation of bromodeoxyuridine (BrDU) into cell nuclei was used. It was found that the tripeptide significantly suppressed the proliferation of the colonic crypts in normal, carcinogen-untreated rats. However, it failed to suppress the cell proliferation of DMH-induced colonic adenocarcinomas or adenomas and produced only a slight, statistically insignificant decrease of the BrDU labelling index in hyperplastic colonic mucosa of DMH-treated rats. These findings suggest that the process of carcinogenesis might 'switch off' the local negative control of the colonic cell proliferation exerted by endogenous CMI.

Adenocarcinoma↗
PubMed1993

Comparison of the antiproliferative effects of colon mitosis inhibitor, thyroliberin and the somatostatin analog octreotide on rat colonic mucosal epithelial cells.

The effects of colon mitosis inhibitor (CMI), thyroliberin (TRH), and the somatostatin analogue octreotide (SMS 201-995) on rat colonic mucosal epithelial cell proliferation were studied. As an index of cell proliferation the incorporation of bromodeoxyuridine (BrDU) into cell nuclei was used. It was found that all three peptides inhibited the colonic mucosal epithelial cells proliferation, but the time course of inhibition was different. The effect of SMS 201-995 occurred 12 h after the peptide injection, while CMI and TRH suppressed the proliferation after 24 h. These observations suggest that the mechanisms of the antiproliferative actions of somatostatin and of related tripeptides CMI and TRH are different.

Animals↗
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

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↗
PubMed1990

Effects of metoclopramide on rat spleen lymphocyte proliferation.

The effect of metoclopramide on proliferation of spleen lymphocytes in rats was examined. The rate of [3H]thymidine incorporation into DNA was used as an index of lymphocytes proliferation. It was shown that the incorporation of [3H]thymidine into DNA of spleen lymphocytes in the rats treated with metoclopramide was significantly higher than that in the control group. The effects of various concentrations of prolactin and metoclopramide on [3H]thymidine uptake by DNA of spleen lymphocytes was also studied in vitro. It was shown that: 1, Prolactin, at the concentration of 1 and 0.1 ng/ml significantly increased [3H]thymidine incorporation into DNA of spleen lymphocytes. Metoclopramide in all the examined concentrations also caused a significant proliferogenic effect on lymphocytes.

Animals↗
PubMedDate not supplied

Effects of somatostatin and its analogues on tyrosine kinase activity in rodent tumors.

The effects of native somatostatin-14 (SS-14) and of its two analogues, octreotide and CH-275, on the activity of tyrosine kinases (TK) in two rodent tumors (rat pituitary tumor and murine colonic cancer) were studied in vitro. The activity of TK was measured in tissue homogenates using gamma[(32)P]ATP as the donor of the phosphoryl group and poly(Glu(80), Tyr(20)) as a substrate. It was found that native SS-14 inhibited TK activity in both investigated tumors. Octreotide, which acts preferentially via somatostatin receptor subtype 2 (SSTR2), was very effective in inhibiting TK activity in the rat pituitary tumor, but it is a rather weak inhibitor of TK activity in murine colonic cancer. CH-275, a selective ligand of the SSTR1 subtype of SS receptors, suppressed TK activity in the pituitary tumor but was ineffective in the colonic cancer. It is hypothesized that the effect of neuropeptide somatostatin (SS-14) on murine colonic cancer is exerted via the subtype of receptor which does not interact with CH-275 and has no or low affinity for octreotide (SSTR 4, 3 or 5?).

Animals↗
PubMedDate not supplied

Somatostatin analogue octreotide and melatonin inhibit bromodeoxyuridine incorporation into cell nuclei and enhance apoptosis in the transplantable murine colon 38 cancer.

There is much evidence of the antiproliferative activity of somatostatin (SS) and melatonin (Mel) upon the normal and neoplastic tissues. It has also been found, that both substances are able to alter, under certain conditions, apoptotic processes. Recently, it has been postulated that apoptosis plays a pivotal role in the control of tumour growth. So far, there is no data about the effect of SS analogue--octreotide (Sandostatin, SMS) and Mel on the apoptosis of colon cancer cells. The aim of this study is to examine the effects of SMS and Mel administered separately or together on apoptosis, bromodeoxyuridine incorporation and weight of tumours in the murine transplantable Colon 38 cancer. The male mice were implanted subcutaneously (s.c.) with a suspension of Colon 38 cells. After 6 days, the animals were subcutaneously injected with SMS, Mel, SMS and Mel together (once daily at 6-8 p.m., for 6 days). The incorporation of bromodeoxyuridine (BrDU) into cell nuclei was used as an index of cell proliferation (labelling index-LI). The in situ labelling of nuclear DNA fragmentation according to TUNEL method was considered as an apoptotic index (AI). Given separately, both SMS and Mel significantly decreased the LI and increased the AI. However, we have not observed any additive effect of SMS and Mel on either BrDU incorporation or apoptosis. The mean AI in the group treated jointly with SMS and Mel was significantly lower than in groups treated separately with SMS or Mel. It was also found, that the proliferation/apoptosis ratio were significantly lower in the group treated with SMS or MEL, which means that the imbalance between these two processes changed in favour of cell death. Possibly, the observed antitumour effects of these two substances could be due to this alteration.

Adjuvants, Immunologic↗