Mukaddes Gumustekin

Effect of Melatonin on Testicular Damage in Streptozotocin-Induced Diabetes Rats

Background: It is well known that diabetes mellitus is associated with impairment of testicular function. In the present study, we aimed to demonstrate the effect of melatonin on testicular damage in male rats with streptozotocin (STZ)-induced diabetes. Methods: Male Wistar rats were divided into 4 groups: (1) control group, (2) melatonin-treated nondiabetic group, (3) diabetic group and (4) melatonin-treated diabetic group. Diabetes was induced by STZ injection. Melatonin was administered intraperitoneally at the dose of 10 mg/kg for 5 days. Testicular damage was examined by using hematoxylin and eosin staining and periodic acid-Schiff staining, and apoptosis was determined by terminal-deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL). Potential disorders associated with seminiferous tubular sperm formation were evaluated using the Johnsen score. Results: Diabetic rats showed a reduction in seminiferous tubule diameter, increased thickening of the basement membrane in seminiferous tubules and degenerated germ cells. TUNEL-positive cells were significantly more numerous in diabetic rats than in control rats. Melatonin significantly attenuated the diabetes-induced morphological changes and germ cell apoptosis in the diabetic rat testis. The number of polymorphonuclear leukocytes was significantly decreased in group 4 when compared to group 3. Conclusions: These results suggest that intraperitoneal administration of melatonin for 5 days is a potentially beneficial agent to reduce testicular damage in adult diabetic rats, probably by decreasing oxidative stress.

HGF/c-Met Overexpressions, but not Met Mutation, Correlates with Progression of Non-small Cell Lung Cancer

Hepatocyte Growth Factor (HGF) and its receptor c-Met are suggested to play an important role in progression of solid organ tumors by mediating cell motility, invasion and metastasis. Overexpression of HGF and c-Met have been shown in non-small-cell lung cancer (NSCLC). However, their role in tumor progression is not clearly defined. The aim of this study is to determine the role of HGF/c-Met pathway and its association with invasion related markers and clinicopathologic parameters in NSCLC. Immunohistochemical analysis was performed on 63 paraffin-embedded NSCLC tumor sections. The expressions of invasion related markers such as Matrix Metalloproteinases (MMPs) 2 and 9, Tissue Inhibitor Metalloproteinase (TIMP) 1 and 3 and RhoA were also examined. Co-expression of HGF/c-Met was significantly associated with lymph node invasion and TIMP-3 and RhoA overexpressions. There were positive correlation between TIMP-3 overexpression and advanced stage and negative correlation between RhoA overexpression and survival. DNA sequencing for Met mutations in both nonkinase and tyrosine kinase (TK) domain was established. A single nucleotide polymorphism (SNP) in sema domain and two SNPs in TK domain of c-Met were found. There was no statistically significant correlation between the presence of c-Met alterations and clinicopathologic parameters except shorter survival time in cases with two SNPs in TK domain. These results suggest that HGF/c-Met might exert their effects in tumor progression in association with RhoA and probably with TIMP-3. The blockade of the HGF/c-Met pathway with RhoA and/or TIMP-3 inhibitors may be an effective therapeutic target for NSCLC treatment.

Effects of repeated administered ghrelin on chronic constriction injury of the sciatic nerve in rats.

Chronic constriction injury (CCI) is a peripheral mononeuropathic pain model that is caused by an injury to the peripheral nervous system and refractory to available conventional treatment. Mechanisms involved in neuropathic pain are still unclear. Previous studies reveal that proinflammatory cytokines contribute to CCI-induced peripheral nerve pathology. Ghrelin, a novel identified gastric peptide, has been shown to have antinociceptive activity and also anti-inflammatory properties by decreasing proinflammatory cytokines. Therefore, the aim of the present study was to investigate the effects of ghrelin on the CCI and its relationship with proinflammatory cytokines in rats. Wistar rats underwent sciatic nerve ligation to induce CCI fallowed by repeated ghrelin administrations (50 and 100microg/kg i.p., once daily) for a period of 14 days. Mechanical hyperalgesia was assessed before surgery and at day 14 after CCI. TNF-alpha, IL-1beta and IL-6 were measured in blood and spinal cord. The changes of sciatic nerve was assessed histologically by both light and electron microscopy. Ghrelin attenuated mechanical hyperalgesia, reduced spinal TNF-alpha and IL-1beta levels and enhanced sciatic nerve injury with correlated morphometric recovery. These results indicate that the protective effect by ghrelin in the spinal cord is mediated through the suppression of TNF-alpha and IL-1beta. Thus ghrelin may be a promising peptide in the management of neuropathic pain.

Possible involvement of ghrelin on pain threshold in obesity

Pain threshold (or perception) can increase or decrease according to some factors like gender, depression or individual differences. Also, previous studies showed that pain threshold can change in obesity but, these studies on the effects of obesity on pain threshold have given controversial results. In the obese people who were exposed to pain stimulation to determined pain threshold, an increased pain threshold was observed. Contrarily, in the studies using electrophysiological test had lower pain threshold, which indicates a reverse correlation between degree of overweight and the threshold of the nociceptive reflex. These studies indicate possible interrelationships between the endogenous opioids, nociception and obesity or eating behavior. Nevertheless, its mechanism is still unclear. The endocrine changes that play an important role in obesity can lead an increase or decrease in pain threshold. There are a few researches about these hormonal factors which are related to pain pathways, that they are nociceptive (like leptin) or antinociceptive effect (like ghrelin, orexin A and B). Ghrelin is one of the hormones which is related to obesity. There are studies which prove the relationship between this hormone and the systems that play a role in pain modulation in the brain. However, there is no previous knowledge about the effects of ghrelin on pain threshold in obesity. But, many strong evidence are present to hypothesise that ghrelin may have effects on pain threshold. Obesity and fasting are the two main situations in which ghrelin secretion is mostly modified. Circulating ghrelin levels negatively correlate with BMI, meaning increased ghrelin secretion during fasting, malnutrition, cachexia, and in anorexia nervosa and reduced ghrelin secretion in obesity. Therefore, we have the opinion that ghrelin play an important role in obesity-pain relationship and/or regulate other systems that are related to pain pathway. Based on the above analyses, we propose a hypothesis that the diminution of the susceptibility to pain in lean subjects/animals may be induced by the increase in endogenous ghrelin activity, or increased of the susceptibility to pain in obese subject/animals may be induced by the decrease in endogenous ghrelin activity.

Effects of Subchronic Parathion Exposure on Cyclosporine Pharmacokinetics in Rats

Parathion undergoes enzymatic oxidation by hepatic cytochrome P-450 (CYP450) enzymes to the active metabolite paraoxon. Consequently, alterations in CYP450- dependent oxidation may affect the pharmacokinetics and pharmacodynamics of drugs that are metabolized in the liver. The CYP3A family is known to be responsible for the majority of cyclosporine metabolism. The aim of the present study was to assess the disposition kinetics of cyclosporine during subchronic parathion exposure. Male Wistar rats were administered either water or two different doses of parathion (1/100 LD50, 1/25 LD50; LD50 = 14 mg/kg) by gavage for 6 wk. Subsequently, rats in each experimental group received a single oral dose of cyclosporine (10 mg/kg), and serial blood samples were drawn from the carotid artery over a period of 48 h. Pharmacokinetic analysis showed that parathion increased the blood cyclosporine concentration twofold as evidenced by AUC (area under the curve), half life (t ½) and peak plasma concentration (C max). This may be due to inhibition of cyclosporine metabolism, an interaction that may be of clinical relevance in immunosuppression therapy.

The interaction of the diltiazem with oral and intravenous cyclosporine in rats

SummaryThis study investigated the effect of diltiazem on the bioavailability of oral and intravenous cyclosporine (CsA) in rats. While control rats received normal saline, experimental groups received 60 or 90 mg/kg diltiazem orally for 3 days. Each group divided into 2 equal groups that received a single oral dose or i.v. injection of CsA. Pharmacokinetic parameters were analyzed by nonparametric analysis of variance. Pretreatment with 60 or 90mg/kg diltiazem decreased the area under the blood CsA concentration-time curve (AUC) of oral CsA compared to control group (54.5% and 65.5% for AUC0–24, 57.6% and 62.2% for AUC0–∞, respectively, p<0.05). Mean CsA maximum concentration (Cmax) decreased from 0.4 + 0.1 μg/ml to 0.1 ±0.0 μg/mL in rats pretreated with 90mg/kg diltiazem (p<0.05). The absolute bioavailability after oral administration (Fp.o) in the 60 or 90mg/kg diltiazem groups were lower than the control group (9.6% and 8.5% versus 22.6%). Pretreatment with 90mg/kg but not 60mg/kg of diltiazem increased the AUC0−8, elimination half-life (t1/2 ) of intravenous CsA (116.0 %, 219.2 %, respectively, p<0.05) and decreased the intravenous CsA clearence (CLi.v) (62.9 %, p<0.05). Diltiazem decreased the bioavailability of oral CsA, while it increased the bioavailability of intravenous CsA. One must consider this interaction when administering oral or intravenous CsA concomitantly with diltiazem.

Heparin treatment increases thioredoxin interacting protein expression in hepatocellular carcinoma cells

Heparins play an important role in cell growth, differentiation, migration and invasion. However, the molecular mechanisms of heparin mediated cellular behaviors are not well defined. To determine the effect of heparin on gene expression, we performed a cDNA microarray in a hepatocellular carcinoma cell line and found that heparin regulates transcription of genes involved in glucose metabolism. In this study, we showed a new role of heparin in the regulation of thioredoxin interacting protein, which is a major regulator of glucose metabolism, in hepatocellular carcinoma cell lines. We determined the importance of a unique carbohydrate response element located on its promoter for the heparin-induced activation of thioredoxin-interacting protein and the modulatory role of heparin on nuclear accumulation of carbohydrate response element associated proteins. We showed the importance of heparin mediated histone modifications and down-regulation of Enhancer of zeste 2 polycomb repressive complex 2 expression for heparin mediated overexpression of thioredoxin-interacting protein. When we tested biological significance of these data; we observed that cells overexpressing thioredoxin-interacting protein are less adhesive and proliferative, however they have a higher migration and invasion ability. Interestingly, heparin treatment increased thioredoxin-interacting protein expression in liver of diabetic rats. In conclusion, our results show that heparin activates thioredoxin-interacting protein expression in liver and hepatocellular carcinoma cells and provide the first evidences of regulatory roles of heparin on carbohydrate response element associated factors. This study will contribute future understanding of the effect of heparin on glucose metabolism and glucose independent overexpression of thioredoxin-interacting protein during hepatocarcinogenesis.

The Role of Rac1 on Carbachol‐induced Contractile Activity in Detrusor Smooth Muscle from Streptozotocin‐induced Diabetic Rats

This study was designed to determine the role of the small GTPase Rac1 on carbachol‐induced contractile activity in detrusor smooth muscle using small inhibitor NSC 23766 in diabetic rats. Rac1 expression in bladder tissue was also evaluated. In the streptozotocin (STZ)‐induced diabetic rat model, three study groups were composed of control, diabetic and insulin‐treated diabetic subjects. The detrusor muscle strips were suspended in organ baths at the end of 8–12 weeks after STZ injection. Carbachol (CCh) (10−9–10−4 M) concentration–response curves were obtained both in the absence and in the presence of Rac1 inhibitor NSC 23766 (0.1, 1 and 10 μM). Diabetes‐related histopathological changes and Rac1 expressions were assessed by haematoxylin and eosin staining and immunohistochemical staining, respectively. CCh caused dose‐dependent contractile responses in all the study groups. Rac1 inhibitor NSC 23766 inhibited CCh‐induced contractile responses in all groups, but this inhibition seen in both diabetes groups was greater than in the control group. Histological examination revealed an increased bladder wall thickness both in the diabetes and in the insulin‐treated diabetes groups compared to the control group. In immunohistochemical staining, expression of Rac1 was observed to be increased in all layers of bladder in both diabetic groups compared to the control group. In the diabetic bladders, increased expression of Rac1 and considerable inhibition of CCh‐induced responses in the presence of NSC 23766 compared to those of the control group may indicate a specific role of Rac1 in diabetes‐related bladder dysfunction, especially associated with cholinergic mediated detrusor overactivity.

The Effect of Insulin Treatment on Rac1 Expression in Diabetic Kidney

This study was designed to evaluate the renoprotective effect of insulin on diabetic nephropathy through Rac1 inhibition. Twenty Wistar rats were divided into three groups: control (C), diabetic (D), and insulin-treated diabetic (D + I). Diabetes was induced by a single streptozotocin (STZ) injection (45 mg/kg i.p.) in adult male rats. Diabetic animals were treated subcutaneously with insulin (6 U/kg), or saline once a day for 8 weeks. Age-matched control rats received only saline. The kidney tissue samples were analyzed by immunohistochemical staining for Rac1 and cleaved caspase-3 expressions and using the TUNEL method for determining apoptotic cells. Diabetes increased the number of TUNEL (+) cells and cleaved caspase-3 and Rac1 expression levels in kidney. Administration of insulin for 8 weeks reduced Rac1 expression and ameliorated histopathological changes in kidney of STZ-induced diabetes model. These results may suggest that the renoprotective effect of insulin at least partly results from inhibition of Rac1 overexpression.

Rational pharmacotherapy training for fourth-year medical students.

Objectives: In this study we aimed to evaluate the impact of Rational Pharmacotherapy (RPT) course program, reinforced by video footages, on the rational pharmacotherapy skills of the students. Materials and Methods: RPT course program has been conducted in Dokuz Eylul University School of Medicine since 2008/9. The course has been organised in accordance with World Health Organisation (WHO) Good Prescribing Guide. The aim of the course was to improve the problem solving skills (methodology for selection of the (p)ersonel-drug, prescription writing and informing patient about his illness and drugs) and communication skills of students. The impact of the course has been measured by pre/post-test design by an objective structured clinical examination (OSCE). In academic year 2010/11, to further improve OSCE score of the students we added doctor-patient communication video footages to the RPT course programme. During training, the students were asked to evaluate the doctor-patient communication and prescription on two video footages using a checklist followed by group discussions. Results: Total post-test OSCE score was significantly higher for 2010/11 academic year students (n = 147) than it was for 2009/10 year students (n = 131). The 2010/11 academic year students performed significantly better than the 2009/10 academic year students on four steps of OSCE. These steps were “defining the patients problem”, “specifying the therapeutic objective”, “specifying the non-pharmacological treatment” and “choosing a (drug) treatment, taking all relevant patient characteristics into account”. Conclusions: The present study demonstrated that the implementation of video footages and group discussions to WHO/Good Prescribing Method improved the fourth-year medical students’ performance in rational pharmacotherapy skills.