Background: It is well known that nutritional habits, sleeping patterns and meal frequency have profound effects on maintaining human health. Ramadan is a religious month for Islam, during which Muslims do not eat and drink during the daylight hours. The duration of restricted food and beverage intake is approximately 12 h/day for 1 month, which makes Ramadan a model of prolonged intermittent fasting. Methods: In order to evaluate the effects of long-lasting modifications of food intake on inflammatory markers and biochemical parameters 40 healthy volunteers of normal weight [20 females aged between 20 and 38 years, 20 males aged between 23 and 39 years, body mass index (BMI) <25 kg/m²] who fasted during Ramadan and another 28 healthy age- and BMI-matched volunteers (14 males, 14 females) who did not fast participated in the study. Venous blood samples were taken 1 week before Ramadan, during the last week of Ramadan and 3 weeks after Ramadan. Serum interleukin-6 (IL-6), C-reactive protein (CRP), homocysteine, vitamin B₁₂, folate, total cholesterol (TC), triglycerides, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels were measured. Results: No significant changes were observed in serum total cholesterol, triglycerides and LDL levels. TC/HDL ratio (HDL risk factor) was decreased during and after Ramadan in both genders in the fasting group while there were no changes in the nonfasting group. IL-6 (p < 0.001), CRP (p < 0.001) and homocysteine (p < 0.01) levels were significantly low during Ramadan in the fasting subjects of both genders when compared to basal values (1 week before Ramadan). Conclusion: Our results demonstrate that prolonged intermittent fasting in a model like Ramadan has some positive effects on the inflammatory status of the body and on the risk factors for cardiovascular diseases such as homocysteine, CRP and TC/HDL ratio.

Background: During Ramadan, Muslims fast during the daylight hours for a month. The duration of restricted food and beverage intake is approximately 12 h/day which makes Ramadan a unique model of intermittent fasting. Many physiological and psychological changes are observed during Ramadan that are probably due to the changes in eating and sleeping patterns. Methods: Serum total cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), prothrombin time, activated partial thromboplastin time (aPTT), plasma fibrinogen, D-dimer and homocysteine levels were measured in 24 healthy fasting volunteers (12 females, 12 males) aged 21–35 years. Venous blood samples were taken 1 week before Ramadan, on the 21st day of Ramadan and 20 days after Ramadan. Results: No significant changes were observed on serum total cholesterol, triglycerides and LDL levels. HDL levels were significantly elevated during Ramadan (p < 0.001) and 20 days after Ramadan (p < 0.05). Prothrombin time, aPTT, fibrinogen and D-dimer levels were in the physiologic limits in all samples but D-dimer levels were significantly low at the end of Ramadan in comparison to pre- and post-fasting levels (p < 0.001). Homocysteine levels, being still in reference ranges, were low during Ramadan (p < 0.05) and reached the pre-fasting levels after Ramadan. Conclusion: Our results demonstrate that intermittent fasting led to some beneficial changes in serum HDL and plasma homocysteine levels, and the coagulation status. These changes may be due to omitting at least one meal when the body was particularly metabolically active and possibly had a low blood viscosity level at the same time. We conclude that intermittent fasting may have beneficial effects on hemostatic risk markers for cardiovascular diseases.

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Cyclophosphamide (Cyc) is known to cause ovotoxicity and infertility in women. Our aim is to investigate the possible ovotoxic effects of Cyc and possible antioxidant and protective effects of blue-green algae, Spirulina (Sp), in rat ovaries. Eighteen rats were given: group I ( = 6, control); group II ( = 6, CP), a single dose Cyc; group III ( = 6, Sp+Cyc), 7 days Sp+single dose Cyc. Tissue malondialdehyde (MDA) levels, superoxide dismutase (SOD), and catalase (CAT) activities are assessed biochemically. Normal and atretic primordial and primary follicle counts for all sections obtained for each ovary are calculated. Mean number of follicle counts for each group are compared. In Sp+Cyc group, tissue MDA levels were significantly lower than those in the CP and higher than those in the C group (CP > Sp+Cyc > C). Tissue SOD activity was significantly higher in Sp+Cyc group than that in the CP group and lower than that in the C group (C > Sp+Cyc > C). No statistically significant difference was found between the ovarian CAT activities in any group. Histomorphometrically, there was also no significant difference between the mean numbers of normal and atretic small follicle counts. Our results suggest that single dose Cyc has adverse effects on oxidant status of the ovaries and Sp has protective effects in Cyc-induced ovotoxicity.

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Objective: In this study the role of 17b-estradiol (E2) in the regulation of endothelin-1 (ET-1) mRNA expression and secretion was investigated in cultured human umbilical vein endothelial cells (HUVECs). Methods: Endothelial cells were either deprived of or treated 29 27with 17b-estradiol (10 , 10 M) for 48 h. After the incubation, the effect of E2 on ET-1 gene expression was evaluated by Northern blot analysis. ET-1 release into the media was measured by radioimmunoassay after 6 h of incubation under basal conditions and upon stimulation with thrombin (4 U / ml). In addition, the cyclic guanosine 59-monophosphate (cGMP) content of cells was assayed by immunoassay. In order to exclude the role of nitric oxide (NO) in E2-induced effects on endothelin-1 gene expression and secretion, nitric oxide synthase (NOS) inhibitor, N-nitro L-arginine methyl ester (1 mM) (L-NAME) was added to the media of some cultures. Results: 27Incubation of HUVECs with 10 and 10 M E2 for 48 h resulted in a 30 and 47% inhibition of ET-1 mRNA expression, respectively. Incubation with E2 also decreased the basal and thrombin-stimulated ET-1 release while increasing the cGMP content of cells significantly. NOS inhibitor L-NAME increased the release of ET-1 from E2-incubated cells but did not alter the ET-1 release from hormone-deprived cells. However, ET-1 secretion of E2-treated cells were significantly less than the deprived ones. Northern blot analyses also demonstrated that inhibition of NOS only partly attenuated the effect of E2 on ET-1 gene expression. In the presence of 27 L-NAME, treatment with 10 M E2 caused a 12% decrease in ET-1 gene expression. Conclusion:The results demonstrate that E2 may play both direct and indirect role in regulation of ET-1 gene expression and production in human endothelial cells. E2-induced increase in NO but decrease in ET-1 production may partly explain the mechanism of the protective effects of the hormone on the cardiovascular system.

SummaryBackground25 (OH) vitamin D3 (25(OH)D) and parathyroid hormone (PTH) are important regulators of calcium homeostasis. The aim of this study was to retrospectively determine the cut–off for sufficient 25(OH)D in a four-season region and the influence of age, seasons, and gender on serum 25(OH)D and PTH levels.MethodsLaboratory results of 9890 female and 2723 male individuals aged 38.8±22.1 years who had simultaneous measurements of 25(OH)D and PTH were retrospectively analyzed by statistical softwares. Serum 25(OH)D and PTH levels were measured by a mass spectrometry method and by an electrochemiluminescence immunoassay, respectively.ResultsMean serum 25(OH)D levels showed a sinusoidal fluctuation throughout the year and were significantly (p<0.01) higher in summer and autumn. On the other hand, PTH levels were significantly higher (p<0.01) in women and showed an opposite response to seasonal effects relative to 25(OH)D. Lowest levels of 25(OH)D were detected in people aged between 20 and 40 years whereas PTH hormone levels were gradually increasing in response to aging. The significant exponential inverse relationship that was found between PTH and 25(OH)D (PTH=exp(4.12–0.064*sqrt(25(OH)D)) (r=–0.325, R– squared=0.105, p<0.001)) suggested that the cut–off for sufficient 25(OH)D should be 75 nmol/L.ConclusionsOur retrospective study based on large data set supports the suitability of the currently accepted clinical cut–off of 75 nmol/L for sufficient 25(OH)D. However, the issue of assessing Vitamin D deficiency remains difficult due to seasonal variations in serum 25(OH)D. Therefore, PTH measurements should complement 25(OH)D results for diagnosing Vitamin D deficiency. It is imperative that seasonally different criteria should be considered in future.

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