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Bogdan Marek

Publications and source records attributed to Bogdan Marek.

30 records · Page 2Linked to original sources
PubMed2002

The influence of pinealectomy and melatonin administration on the dynamic pattern of biochemical markers of bone metabolism in experimental osteoporosis in the rat.

BACKGROUND AND OBJECTIVES: There have been suggestions in literature that characteristic changes of bone mass in osteoporosis may be related to the melatonin (Mel): The aim of this study was to demonstrate whether pinealectomy and Mel administration can affect postmenopausal osteoporosis processes induced in female rats by way of ovariectomy. METHODS: The study included 198 animals; 6 remained intact (0), 96 were ovariectomized (Ox), and the remaining ones underwent a sham operation (SOx). Two weeks after surgery, the rats were divided into eight groups: 1) SOx + SPx, 2) SOx + SPx + Mel, 3) Ox + SPx, 4) Ox + SPx + Mel, 5) SOx + Px, 6) SOx + Px + Mel, 7) Ox + Px, 8) Ox + Px + Mel. Animals from the 5th, 6th, 7th and 8th groups were pinealectomized (Px) while the remaining ones underwent a sham operation (SPx). Two weeks after surgery Mel (50microg/100g of bm) were administered intraperitoneally in rats in the 2nd, 4th, 6th and 8th groups while the remaining animals were administered with solvent only (5% solution of ethyl alcohol in physiological saline). Rats were administered the Mel solution or the solvent daily between 5 and 6 pm during a 4-week period. At the appropriate time, i.e. prior to surgery (group 0) and after 6, 12, 18 and 24 weeks from Px or SPx (time subgroups a, b, c and d) the animals were placed separately in metabolic cages (from 6.30 until 9.30 am) in order to collect urine aliquots for HYP and Ca determinations. The blood for the assay of ALP, PICP and ICTP was collected within the next 24 hours at 8 am (rats killed by decapitation). RESULTS: The study has shown that pinealectomy had inducing, while exogenous Mel suppressing effect upon the level of investigated markers of bone metabolism; these changes were more pronounced in ovariectomized rats. Administration of Mel only partially levelled changes of bone metabolism caused by pinealectomy. In rats with preserved pineal gland effect of Mel on bone turnover markers was less pronounced. After discontinuing administration of Mel distinct tendency to increase studied biochemical markers of bone metabolism was shown. CONCLUSION: Our findings suggest that Mel is an important modulator of experimental osteoporosis processes induced in female rats by way of ovariectomy.

Alkaline Phosphatase↗
PubMed2002

Does the negative correlation found in breast cancer patients between plasma melatonin and insulin-like growth factor-I concentrations imply the existence of an additional mechanism of oncostatic melatonin influence involved in defense?

BACKGROUND: Insulin-like growth factor-I (IGF-I) is probably involved in promoting both normal and neoplastic cell growth, neoplastic transformation processes, angiogenesis, and neoplasma progression. On the other hand, one possible mechanism of the oncostatic action of melatonin is its influence on the action and/or release of the growth factors that stimulate neoplastic cell growth. Quantitative changes in melatonin and IGF-I, as well as an imbalance between melatonin and IGF-I, may affect the growth of breast cancer cells and exacerbate the disease. The aim of our research was to study the interactions between plasma melatonin and IGF-I concentrations in pre-menopausal breast cancer patients. MATERIAL/METHODS: Our research involved 24 breast cancer patients (mean age 43 +/-6) with stage II breast cancer (Bloom and Richardson classification), confirmed by histological studies, and were 4 weeks after radical mastectomy. The control group consisted of 16 healthy women volunteers (mean age 44 +/- 5). RESULTS: No statistically significant relations were found between mean plasma melatonin and IGF-I concentrations in the two study groups. In the breast cancer group the correlation coefficient between IGF-I concentration in plasma and melatonin was r = -0.392 (p = 0.058). CONCLUSIONS: The negative correlation between the plasma melatonin and IGF-I concentrations in the breast cancer patients we studied could reach statistical significance in a larger population. The presence of such a negative correlation between plasma melatonin and IGF-I concentrations in patients with neoplastic disease may imply the existence of an additional defense mechanism based on the oncostatic influence of melatonin.

Adult↗
PubMed2002

Circadian rhythm of melatonin in patients with colorectal carcinoma.

OBJECTIVE: The aim of the study was pineal gland function assessment on the base of daily rhythm study and mean daily melatonin (MEL) concentrations in serum in patients with colorectal carcinoma. MATERIAL AND METHODS: Studies were performed in 12 women at the age of 63.17+/-5.90 years and 21 men aged 58.95+/-11.32 years with large intestine adenocarcinoma. The control group consisted of 28 healthy volunteers at comparable age. During the circadian study blood samples for the measurement of melatonin (MEL) were collected every 4 hours during 12 h. MEL concentrations were assessed with the use of RIA methods. Statistical analysis of circadian rhythms of MEL was carried out with the use of cosinor method according to Halberg. RESULTS: Existence of daily rhythm of MEL secretion was shown in all studied groups. A significant decrease of amplitude of rhythm and secretion of MEL at nocturnal hours in comparison with the control group was shown in the group of women with large intestine carcinoma. A significant decrease of mesor value and amplitude of MEL rhythm as a consequence of decrease of MEL secretion at nocturnal and morning hours was observed in the group of ill men. CONCLUSIONS: Decrease in melatonin circadian rhythm amplitude as a consequence of its lowered nocturnal secretion occurred in all patients with colorectal carcinoma. Abnormalities in daily rhythm of melatonin secretion were more intensified in men with large intestine carcinoma, which leads to suppression of mean daily hormone concentration.

Adenocarcinoma↗
PubMed2002

Circadian rhythm of melatonin in postmenopausal asthmatic women with hormone replacement therapy.

OBJECTIVE: The aim of the study was to check if in postmenopausal women such a disease as asthma and use of hormone replacement therapy (HRT) influence daily melatonin (MEL) secretion. MATERIAL AND METHODS: Studies were performed in 55 asthmatics (treated and not treated with glucocorticosteroids) and 20 healthy postmenopausal women (aged 48-60) before HRT and after 6 months of transdermal 17beta-estradiol and medroxyprogesterone acetate treatment (cyclical method). During the circadian study blood samples for the measurement of MEL were collected every 3 hours during the day. MEL concentrations were assessed with the use of RIA methods. Statistical analysis of the circadian rhythm was performed with the use of cosinor test according to Halberg et al. RESULTS: Existence of daily rhythm of MEL secretion was shown in all studied groups, before as well as after HRT. A significant decrease of mesor and amplitude's rhythm was observed in the group of women with asthma treated with glucocorticosteroids (GC) before and after HRT use in relation to women not treated with GC and the control group. Secretion of MEL in these patients was lower at nocturnal hours. A significant decrease of mean daily MEL secretion in relation to values before HRT use was shown in all groups. CONCLUSIONS: Asthmatic postmenopausal women treated with GC show lowered circadian secretion of melatonin as a consequence of lowering its secretion at nocturnal hours. Hormonal replacement therapy causes a decrease of daily melatonin secretion in healthy as well as asthmatic women, not disturbing circadian rhythm of this hormone's secretion.

Aged↗
PubMed2001

Acromegaly and the risk of cancer.

Recent studies suggest that acromegaly might predispose to an increased risk of benign and malignant neoplasms, thus influencing the final outcome of the disease. The exact mechanism of neoplastic events in acromegaly has not been completely clarified. Several studies indicate an autocrine-paracrine role for growth hormone (GH) and insulin-like growth factor-I (IGF-I) in the proliferation of normal and neoplastic cells. The paper reviews the results of molecular, clinical and epidemiological data supporting a role for GH-IGF-I action in colon, prostate, breast and lung carcinogenesis inpatients with acromegaly.

Journal Article↗
PubMedDate not supplied

The relationship between the daily profile of chosen biochemical markers of bone metabolism and melatonin and other hormone secretion in rats under physiological conditions.

BACKGROUND: The mechanism of generating and synchronizing daily rhythms of bone and mineral metabolism markers has not been entirely explained. Most studies indicate that LD cycle and/or feeding schedules provide important synchronizers of these rhythms. It seems that endogenous factors, including systemic and local hormones can be important in the mechanism of dependence of bone and mineral metabolism parameters rhythms on LD cycle and feeding schedule. OBJECTIVE: To assess the relationship between the daily profile of chosen biochemical parameters of bone and mineral metabolism (serum ALP, PICP, ICTP and iP and urinary excretion of HYP and total calcium) and daily secretion of MEL, GH/IGF-I axis activity and parathyroid, thyroid, adrenal cortex and gonads function in 48 adult male rats. METHODS: Material for studies was collected every 3 hours within a day. Hormones, PICP and ICTP concentrations were determined with the use of RIA method and ALP, HYP, total calcium and iP values--spectrophotometrically. RESULTS: Existence of a negative correlation between daily oscillations of studied markers of osteogenesis (ALP and PICP) and daily profile of MEL and PTH secretion and positive with daily fluctuations of GH and IGF-I was shown. Moreover, ALP values correlated negatively with daily oscillations of CT. Concentrations of bone resorption markers (ICTP, HYP and total calcium) correlated negatively with daily fluctuations of MEL and positively with GH, IGF-I and thyroid hormones. CONCLUSION: The present results suggest that physiological daily rhythmicity of PTH, MEL, GH, IGF-I and thyroid hormones most probably play an important role in regulating the daily rhythm of biochemical markers of bone metabolism.

Alkaline Phosphatase↗
PubMedDate not supplied

[Influence of pinealectomy and long-term melatonin administration on bone metabolism in orchidectomized rats].

INTRODUCTION: The aim of the study was to demonstrate whether pinealectomy and long-term MEL administration can affect bone metabolism (as evaluated on the basis of serum concentrations of PICP and ICTP) in orchidectomized rats. MATERIAL AND METHODS: The study included 248 adult male Wistar rats; 6 remained intact, 120 were orchidectomized (Orch), and the remaining ones underwent a sham operation (SOrch). Two weeks after surgery, the rats were divided into 8 groups: 1) SOrch + SPx; 2) SOrch + SPx + MEL; 3) Orch + SPx; 4) Orch + SPx + MEL; 5) SOrch + Px; 6) SOrch + Px + MEL; 7) Orch + Px; 8) Orch + Px + MEL. Animals from 5(th), 6(th), 7(th) and 8(th) groups were pinealectomized (Px) while the remaining ones underwent a sham operation (SPx). Two weeks after surgery rats in the 2(nd), 4(th), 6(th) and 8(th) groups were administered MEL (50 microg/100 g of bm) intraperitoneally while the remaining animals were administered solvent only (daily between 5 and 6 pm during a month). The animals were decapitated before the experiment (intact rats), after 2 weeks from Orch and SOrch, Px and SPx, after 4 weeks from MEL or solvent administration and after 4 and 8 weeks from discontinuing administration of MEL, and blood was collected for PICP and ICTP concentrations assays with the use of RIA method. DISCUSSION: In Orch rats, a distinct tendency to increase the studied bone markers, especially ICTP was shown. Pinealectomy had inducing, while MEL suppressing effect upon the level of PICP and ICTP; these changes were more pronounced in Orch + Px and SOrch + Px + MEL groups, respectively. After discontinuing administration of MEL distinct tendency to increase of PICP and ICTP level was shown. CONCLUSIONS: Our findings indicate that MEL is an important modulator of bone tissue metabolism in male rats and that deficiency of MEL concentration may be a co-factor in osteoporosis development.

Animals↗
PubMedDate not supplied

The relation of serum adiponectin and leptin levels to metabolic syndrome in women before and after the menopause.

INTRODUCTION: It is well known that there is a higher prevalence of cardiovascular risk factors and metabolic syndrome (MS) in postmenopausal women. Recently it has become evident that adiponectin and leptin secreted by adipose tissue may be involved in the pathophysiology of MS. THE AIM OF THE STUDY: was to assess the effects of the menopause on the relationships between adiponectin and leptin and different cardiovascular and metabolic risk factors. MATERIALS AND METHODS: A total of 56 postmenopausal women and 75 premenopausal subjects were enrolled in this study. We measured blood pressure, BMI, waist circumference and WHR, triglycerides (TG), high density lipoprotein cholesterol (cHDL) levels and fasting glucose and applied the oral glucose tolerance test (OGTT). Women were categorised as having 0, 1, 2, 3 or more risk factors. The presence of at least 3 abnormalities was defined as MS. Serum was assayed for adiponectin and leptin by the radioimmunoassay (RIA) method. RESULTS: A decline in adiponectin was related to an increased number of MS variables in postmenopausal and premenopausal women. Postmenopausal women with MS had significantly lower adiponectin concentrations than premenopausal women with MS. Serum adiponectin concentrations were inversely correlated to leptin in postmenopausal women. In premenopausal women no clear relationships were found between serum leptin and the number of metabolic disturbances. In contrast to young women, postmenopausal women showed an increase in leptin secretion with a growing number of MS elements. Compared to premenopausal women with MS, postmenopausal women with MS had higher levels of leptin. We found associations between leptin and different risk factors, mainly in the postmenopausal group. When the presence of MS was used as a dependent variable (yes/no) and adiponectin, leptin and menopause status as independent factors, adiponectin and leptin remained significant variables related to MS. CONCLUSION: The significant role of adiponectin in the pathophysiology of MS in premenopausal and postmenopausal women is confirmed in this study. Leptin is correlated with several MS components but this adipocytokine appears to play a role only in postmenopausal women.

Adiponectin↗
PubMedDate not supplied

[Thyroid hormones and the cardiomyocytes].

The authors present the current knowledge on the intracellular mechanisms of thyroid hormone action in the cardiomyocytes. Many of the clinical manifestations of thyroid diseases are due to the ability of thyroid hormone to alter cardiovascular hemodynamics. Triiodothyronine affects the hemodynamic state mainly by its influence on the expression of cardiomyocyte genes. These genes encode both structural and regulatory proteins in the heart (myosin heavy chains, sarcoplasmic reticulum calcium-activated ATP-ase, phospholamban). The impaired myocardium contractile activity in hypothyreosis reminds findings in heart failure and may warrant further exploration of therapeutic approaches using thyroid hormone to improve cardiac function in heart failure.

Animals↗
PubMedDate not supplied

[Unique case of caecum plasmablastic lymphoma CD138(+) in patient with late diagnosed colon neuroendocrine carcinoma].

Neuroendocrine tumors are frequently associated with other primary malignancies. Plasmablastic lymphoma is a rare, aggressive neoplasm, derived from large B-cell, associated with human immunodeficiency virus infection. Plasmablastic lymphoma cells share many cytomorphologic and immunophenotypic features with plasmablastic cells, causing some diagnostic problems. We present a unique case of coexisting two very uncommon neoplasms: plasmablastic lymphoma and neuroendocrine carcinoma in 54-years-old men. This is the first report of caecum localization of plasmablastic lymphoma. Presented case images diagnostic problems in rare neoplasms.

Biomarkers, Tumor↗