Leptin receptor (Ob-R) mRNA expression and serum leptin concentration in patients with colorectal and metastatic colorectal cancer.

The objective of the present study was to investigate the effect of leptin on the progression of colorectal carcinoma to metastatic disease by analyzing the serum leptin concentration and Ob-R gene expression in colon cancer tissues. Tissue samples were obtained from 31 patients who underwent surgical resection for colon (18 cases) and metastatic colon (13 cases) cancer. Serum leptin concentration was determined by an enzyme-linked immunosorbent assay (ELISA) and Ob-R mRNA expression by real-time polymerase chain reaction (RT-PCR) for both groups. ELISA data were analyzed by the Student t-test and RT-PCR data were analyzed by the Mann-Whitney U-test. RT-PCR results demonstrated that mRNA expression of Ob-R in human metastatic colorectal cancer was higher than in local colorectal cancer tissues. On the other hand, mean serum leptin concentration was significantly higher in local colorectal cancer patients compared to patients with metastatic colorectal cancer. The results of the present study suggest a role for leptin in the progression of colon cancer to metastatic disease without weight loss. In other words, significantly increased Ob-R mRNA expression and decreased serum leptin concentration in patients with metastatic colon cancer indicate that sensitization to leptin activity may be a major indicator of metastasis to the colon tissue and the determination of leptin concentration and leptin gene expression may be used to aid the diagnosis.

Leptin receptor (Ob-R) mRNA expression and serum leptin concentration in patients with colorectal and metastatic colorectal cancer

The objective of the present study was to investigate the effect of leptin on the progression of colorectal carcinoma to metastatic disease by analyzing the serum leptin concentration and Ob-R gene expression in colon cancer tissues. Tissue samples were obtained from 31 patients who underwent surgical resection for colon (18 cases) and metastatic colon (13 cases) cancer. Serum leptin concentration was determined by an enzyme-linked immunosorbent assay (ELISA) and Ob-R mRNA expression by real-time polymerase chain reaction (RT-PCR) for both groups. ELISA data were analyzed by the Student t-test and RT-PCR data were analyzed by the Mann-Whitney U-test. RT-PCR results demonstrated that mRNA expression of Ob-R in human metastatic colorectal cancer was higher than in local colorectal cancer tissues. On the other hand, mean serum leptin concentration was significantly higher in local colorectal cancer patients compared to patients with metastatic colorectal cancer. The results of the present study suggest a role for leptin in the progression of colon cancer to metastatic disease without weight loss. In other words, significantly increased Ob-R mRNA expression and decreased serum leptin concentration in patients with metastatic colon cancer indicate that sensitization to leptin activity may be a major indicator of metastasis to the colon tissue and the determination of leptin concentration and leptin gene expression may be used to aid the diagnosis.

NMDA receptor blockage with 2-amino-5-phosphonovaleric acid improves oxidative stress after spinal cord trauma in rats.

STUDY DESIGN: 2-amino-5-phosphonovaleric acid (APV) is an N-methyl-D-aspartate (NMDA) receptor blocker and has neuroprotective properties. This study is aimed at evaluating the effect of APV treatment on oxidative status after spinal cord injury (SCI). METHODS: The experiment was carried out on the following five groups: Group 1: sham operated, non-traumatized; Group 2: with injured spinal cord, no treatment; Group 3: with SCI, injected with 100 microg kg(-1) APV; Group 4: with SCI, injected with 200 microg kg(-1) APV; and Group 5: with SCI, injected with 400 microg kg(-1) APV. SCI was inflicted by epidural compression with a cerebral vascular clip after T9-11 laminectomy. The experiments were completed after 12 h of trauma. Spinal cords were excised for evaluation of superoxide dismutase (SOD), catalase, reduced glutathione (GSH) and malonyldialdehyde (MDA) levels. RESULTS: After SCI, SOD and GSH levels decreased and the MDA level increased significantly. APV treatment decreased the MDA level and increased SOD, catalase and GSH levels. The maximum decrease in MDA was detected in the group treated with 100 microg kg(-1) APV compared with the other groups. The GSH level was significantly increased in the group treated with 200 microg kg(-1) APV. The SOD level was significantly increased in the group treated with 200 microg kg(-1) APV. CONCLUSION: The results of this study have shown that APV treatment creates a dose-dependent antioxidant effect in rats with SCI and may be used for the treatment of SCIs.

Protective effect of high-dose thiamine (B1) on rat detrusor contractility in streptozotocin-induced diabetes mellitus.

We investigated the effect of thiamine (B1) treatment on bladder dysfunction in streptozotocin (STZ)-induced diabetic rats. A total of 40 rats were randomly divided into four groups: a control group, a group given thiamine only, a diabetic group and a diabetic group given thiamine therapy. Diabetes was induced in the rats by 65 mg/kg STZ via an intraperitoneal injection. Thiamine was given 50 mg/kg/day. Diabetic cystopathy was confirmed on cystometry 8 weeks later in diabetic groups. Rats' body and bladder weights were measured. Contractile response to carbachol and potassium chloride (KCl) of detrusor strips in all groups was studied in vitro. The body weights were significantly decreased (p<0.01), the bladder weights were significantly increased (p<0.01), and the cystometric bladder capacity and the residual urine volumes were significantly increased (p<0.001, p<0.01 respectively) in STZ-induced diabetic groups compared to the control group and the group given thiamine only. Contractile responses increased in the diabetic group in high carbachol and KCl concentrations (p<0.01, p<0.01, respectively). On the other hand, there were no differences in the other groups. These data suggest that high-dose thiamine (B(1)) treatment may be beneficial in delaying the progression of diabetic cystopathy in this experimental animal model.

Effect of leptin on renal ischemia-reperfusion damage in rats.

Tumor necrosis factor-alpha (TNF-alpha) has been established as an important mediator in renal ischemia-reperfusion (I/R) injury. Leptin, a product of the ob gene, has been known to exhibit cytoprotective effects on renal tissue, but its effect on renal tissue TNF-alpha level after renal I/R injury in rats remains unknown. The purpose of the study was to evaluate the effects of leptin on renal tissue TNF-alpha, malondialdehyde (MDA), protein carbonyls (PCs) and total sulfydryl group (SH) levels, and plasma nitrite levels after renal I/R injury in rats. The animals were divided into three groups: control, I/R and I/R+leptin. Rats were subjected to renal ischemia by clamping the left pedicle for 45 min, and then reperfused for 1 h. The I/R+leptin group was pretreated intraperitoneally with leptin (10 microg/kg) 30 min before the induction of ischemia. Our results indicate that MDA, TNF-alpha levels, and PCs were significantly higher in the I/R group than those in the control group (p < 0.05). The administration of leptin decreased these parameters (p < 0.05) significantly. The SH level was observed to significantly decrease after I/R injury when compared to the control group (p < 0.05). Leptin treatment significantly increased tissue SH and plasma nitrite levels when compared to the I/R group (p < 0.05). Plasma nitrite levels did not change significantly in I/R when compared to the control. These results suggest that leptin could exert a protective effect on I/R induced renal damage by decreasing TNF-alpha levels and increasing nitrite level.

Effects of dopexamine on rat cardiorenal functions during lipopolysaccharide-induced experimental sepsis.

We aimed to test the protective effect of dopexamine on renal function and systemic haemodynamics in rats with induced sepsis. Female Sprague-Dawley rats were randomized into three equal groups: group 1 (control, received 3% creatinine throughout the experiment); group 2 (sepsis, received 3% creatinine and Escherichia coli lipopolysaccharide [LPS] endotoxin [8 mg/kg per h]); and group 3 (sepsis plus dopexamine, received 3% creatinine, E. coli LPS and dopexamine [1 microgram/kg per min]). Time-adjusted heart rate, systolic, diastolic and mean arterial pressures, urine volume and glomerular filtration rate (from creatinine clearance) were recorded. After bacterial infusion heart rate increased and mean arterial pressure decreased; the fall in mean arterial pressure was less pronounced with dopexamine (group 3) than without (group 2). Dopexamine also induced significant and moderate increases in urine volume and heart rate, respectively. We concluded that dopexamine has some positive inotropic-chronotropic effects and induces favourable responses in renal function.

Effects of clonidine pre-treatment on bupivacaine and ropivacaine cardiotoxicity in rats.

BACKGROUND AND OBJECTIVE: Clonidine has cardiac and systemic effects that can modify the potentially lethal cardiovascular effects of local anaesthetics. We evaluated the effects of clonidine pre-treatment on cardiotoxicity induced by an infusion of bupivacaine or ropivacaine and the success rate of resuscitation in anaesthetized rats. METHODS: Thirty-two Sprague-Dawley rats (250-300 g) were anaesthetized with thiopental and ketamine. Lung ventilation was maintained mechanically, and the electrocardiograph and invasive blood pressure were recorded continuously. Two separate groups of rats were treated with intravenous clonidine 5 microg kg(-1) (n = 16) or saline (n = 16) in a randomized fashion. Fifteen minutes later, each group was randomly subdivided into two equal groups and an infusion of bupivacaine or ropivacaine, 3 mg kg(-1) min(-1), was given until cardiac arrest (asystole) occurred. The times when the cardiotoxic events (25%, 50% and 75% reduction of arterial pressure and heart rate, first dysrhythmia and asystole, respectively), induced by the local anaesthetic, occurred and the resuscitation outcome scores were recorded. RESULTS: Clonidine reduced heart rate and arterial pressure (P < 0.01). Clonidine did not alter cardiotoxicity or the success rate of resuscitation in bupivacaine-treated rats. In the ropivacaine group, clonidine increased the 25%, 50% and 75% reduction times of arterial pressure and the 50% and 75% reduction times of heart rate, times to first dysrhythmia and asystole (P < 0.05). Clonidine also increased the success rate of resuscitation in ropivacaine-treated rats (P < 0.05). CONCLUSIONS: Although pre-treatment with clonidine protects the effects of ropivacaine cardiotoxicity and increases the success rate of resuscitation, it does not affect bupivacaine toxicity.

The mitogenic activity of endothelin-1 on megakaryocytopoiesis in vitro.

Endothelin (ET)-1 induces proliferation of various cells including smooth muscle cells, fibroblasts, glomerular mesangial cells, endothelial cells and osteoblasts. ET-1 also stimulates synthesis of interleukin (IL)-6 in endothelial and bone marrow stromal cells of rat. It is well known that IL-6 modulates megakaryocytopoiesis. Some studies have indicated that megakaryocytes express both ET receptors and they are targets for ET. Therefore we planned to examine the effects of ET-1 on the growth of normal megakaryocytic cells in rat bone marrow primary cell culture. Bone marrow cells were cultured at 37 degrees C, in an incubator atmosphere of 5% CO2 in air and 95% relative humidity for nine days. ET-1 at 10(-7), 10(-8 ) and 10(-11) M, and control with saline were added at the beginning of the experiment protocol. At each day, plasma clots were stained using direct-coloring thiocholin method for acetylcholinesterase activity. Although 10(-7) M ET-1 did not change the proliferation of megakaryocytic cells, this could be due to the presence of over crowded fibroblasts in the same environment. 10(-8) M ET-1 stimulated megakaryocytic cell growth to 234% over the control on the fifth day. ET-1 at a concentration of 10(-11) M also rised the megakaryocytic cell number significantly reaching up to 86% at the sixth day. Our results indicate that ET-1 may modulate the growth of megakaryocytic cells by an autocrine and/or paracrine action.

Cerebral blood flow alterations in progressive communicating hydrocephalus: transcranial Doppler ultrasonography assessment in an experimental model.

OBJECT: In many cases communicating hydrocephalus is the result of impairments in cerebrospinal fluid absorption in the arachnoid villi at the cranial convexity. Reported methods of creating experimental hydrocephalus have not sought to produce an arachnoidal adhesion in the cranial convexity. In this study the authors investigate alterations in cerebral blood flow (CBF) in experimental communicating hydrocephalus induced by the injection of kaolin into the subarachnoid space at the convexity in neonatal rats. METHODS: In neonatal rats, kaolin was injected into the subarachnoid space at the cranial convexity. Assessment of CBF alterations was performed using transcranial Doppler ultrasonography preinjection and at 10 days, 4 weeks, and 8 weeks postinjection. Light microscopy examination was also performed at 4 weeks and 8 weeks postinjection. Conspicuous lateral ventricle enlargements of different dimensions were observed in kaolin-injected rats at 4 to 8 weeks postinjection. The third and fourth ventricles were dilated to a lesser extent. Resistance to CBF and increased mean CBF velocity were apparent 8 weeks after kaolin injection. Further, destruction and even loss of ependymal layers were more prominent at the chronic stage. CONCLUSIONS: The present model may be considered a progressive communicating hydrocephalus because of marked changes in blood flow dynamics and destruction of the ependymal layer at the chronic stage.

Effect of nitric oxide inhibition on rat liver ischemia reperfusion injury.

Objective: to determine the role of nitric oxide (NO) in rat liver ischemia reperfusion we examined the effects of competitive NO synthesis inhibitor L-nitro-arginine-methyl-ester (L-NAME) and NO precursor L-arginin. Methods: 46 Sprague-Dawley rats were divided into five groups. Group 1, sham operated; group 2, 30-min ischemia administered; group 3, 60-min reperfusion administered after ischemia; group 4, 50 mg/kg L-NAME was given i.v. immediately before reperfusion; group 5, 50 mg/kg L-NAME+250 mg/kg L-arginin was given i.v. immediately before reperfusion. At the end of the experiment, liver was removed and superoxide dismutase (SOD), catalase, and malondialdehyde (MDA) were measured, transaminases SGOT and SGPT were measured in sera. Liver was also evaluated histopathologically. Results: transaminase levels were the highest in ischemia reperfusion group. Transaminases in this group were high compared with sham, ischemia, L-NAME and L-arginin groups (***P<0.001, ***P<0.001, *P<0.05, *P<0.05, respectively). SOD activity was 29.8+4 U/mg protein in L-arginin group. This level was the lowest level in all groups. SOD activity in L-arginin group was lower than that of sham and ischemia reperfusion groups (**P<0.01, *P<0.05, respectively). There were no significant differences in catalase activity and MDA levels among groups. Tissue damage was significant in ischemia and ischemia reperfusion groups. Tissue damages in these groups were greater than that of sham group (***P<0.001). In L-NAME treated group, tissue damage was similar to sham group, and significantly less than ischemia reperfusion group and L-arginin group (**P<0.01). Conclusion: even though there was significant tissue damage, we have not observed oxidative stress in the length of ischemia reperfusion period that we have performed. Mechanism of this damage seems to be independent from lipid peroxidation. NO supplementation decreased SOD, but did not cause further tissue damage. NO may dispose O(2)(-) by formation of peroxynitrite. L-NAME did not change lipid peroxidation, but clearly reduced reperfusion injury.

Ischemic-reperfused rat skeletal muscle: the effect of vasoactive intestinal peptide (VIP) on contractile force, oxygenation and antioxidant enzyme systems.

The effect of vasoactive intestinal peptide (VIP) on the nerve-stimulated contraction, tissue oxygenation, lipid peroxidation and antioxidant enzymes activities-superoxide dismutase and catalase was investigated in the rat gastrocnemius muscle exposed to 4 h ischemia-4hr reperfusion. Ischemia caused significant decrease in muscle contractile force, oxygenation and superoxide dismutase enzyme activity. Reperfusion of ischemic muscle increased the muscle contractile force and restored the tissue oxygenation to the baseline level. Superoxide dismutase and catalase activities of reperfused muscle increased significantly. However neither ischemia nor reperfusion affected gastrocnemius muscle malondialdehide (MDA) levels. VIP administration at the onset of reperfusion significantly increased skeletal muscle contractile force and tissue oxygenation even higher than baseline and reperfusion values. VIP also normalized the increased superoxide dismutase and catalase activities of reperfused skeletal muscle. In conclusion, VIP, acting as a powerful antioxidant and preserving contractile machinery seems to be a promising endogenous peptide that can salvage the skeletal muscle from severe ischemia-reperfusion injury.

Relaxing effects of vasoactive intestinal peptide (VIP) on the contractile actions of endothelin-3, histamine, and acetylcholine in isolated guinea pig tracheal smooth muscle with or without epithelium.

The role of VIP on the contractile effects of endothelin-3 (ET-3) (10(-8) M) or a combination of ET-3 plus histamine (Hist) (10(-5) M) or ET-3 plus acetylcholine (Ach) (10(-5) M) were investigated in guinea pig isolated tracheal smooth muscle. Strips of guinea pig trachea, in some of which the epithelium had been removed mechanically, were suspended in organ chambers and isometric tension was recorded. ET-3 contracted the tracheal smooth muscle in a dose-dependent manner ranging from 2 x 10(-12) to 2 x 10(-8) M. The removal of the epithelium significantly potentiated the ET-3-induced contractions. VIP significantly relaxed ET-3 contractile responses about 46 +/- 12% for the intact trachea (p < 0.05) and 39 +/- 6% for the rubbed trachea (p < 0.05). The removal of the epithelium did not significantly change the relaxation effect of VIP on ET-3-induced contraction of guinea pig isolated tracheal smooth muscle. On the other hand, the presence of tracheal epithelium was required for VIP (10(-8)) relaxation in Hist (10(-5)) contracted trachea. Apart from this finding, other Hist and all Ach-induced contractions (10(-5)) of the trachea were not significantly affected by ET-3 (10(-8)) or VIP treatments with or without epithelium. These findings indicate that VIP may play a role in inhibiting the contractile actions of ET-3 in guinea pig trachea and that an intact epithelium is not required for the relaxation but it is required for the VIP relaxation of Hist-induced contraction.

The effect of vasoactive intestinal peptide (VIP) on mast cell invasion/degranulation in testicular interstitium of immobilized + cold stressed and beta-endorphin-treated rats.

The effect of VIP on mast cell invasion/degranulation in testicular interstitium of stressed (immobilization and cold) and beta-endorphin-treated rats were investigated. Fifty-three Wistar male rats were used in four series of experiments. Initially, the effect of immobilization and cold stress on mast cell invasion and degranulation in testicular interstitium was examined in three age group of rats: 15 (n = 6), 30 (n = 6), and 45 (n = 7) days of age. Five animals per age group were used as controls. Because the most obvious effect of the stress on mast cell invasion/degranulation in testicular interstitium was observed in 45-day-old rats, the action of VIP in stressed and beta-endorphin-treated rats was only investigated at this age group. Mast cells and Leydig cells were evaluated by using histochemical and light microscopic protocols. Stress caused mast cell accumulation and degranulation in the testicular interstitium. Stress decreased heparin synthesis and possibly increased histamine content of mast cells. The effect of beta-endorphin was not as high as seen with stress. In some areas of testicular interstitium of stressed rats, there were aplasic and/or inactive Leydig cells. VIP inhibited proliferation and degranulation of mast cells, increased heparin content of the cells, and protected Leydig cells. By way of mast cell accumulation and degranulation in the testicular interstitium, exposure to stress may lead to Leydig cell damage and infertility. VIP may be involved in the protection of normal testicular function under stress conditions.

The effect of vasoactive intestinal peptide (VIP) on superoxide dismutase and catalase activities in renal tissues of rats exposed to hemorrhagic ischemia-reperfusion.

The effect of vasoactive intestinal peptide (VIP) on the activities of superoxide dismutase and catalase was investigated in renal tissues of rats exposed to 30% hemorrhage followed by reperfusion. In addition to enzyme activities, renal tissues were also histologically evaluated. Thirty percent hemorrhage had no significant effect on the activity of either enzyme. Reperfusion altered the activity of renal catalase but not of superoxide dismutase. On the other hand, administration of VIP (25 ng.kg-1) together with shed blood retransfusion protected the renal tissue from hemorrhagic ischemia-reperfusion injury without increasing superoxide dismutase and catalase activity. These results seem to be related either to the inhibitory effect of VIP on production or quenching activity of some reactive oxygen species. In conclusion, VIP may be a novel promising therapeutic approach toward defenses against hemorrhagic ischemia-reperfusion injury as an antioxidant.

Endothelin-induced natriuresis and diuresis are pressure-dependent events in the rat.

The goal of the current study was to determine the mechanism by which doses of endothelin (ET) that do not markedly affect the glomerular filtration rate (GFR) cause a natriuresis and diuresis. ET was infused into pentobarbital-anesthetized female rats at 50 ng.kg-1.min-1 iv for 30 min. In controls (n = 6 rats; n = 5 in all other groups), ET increased mean arterial blood pressure (MAP) from 95 +/- 2 to 131 +/- 2 (SE) mmHg, Na excretion (UNa V) from 0.34 +/- 0.07 to 1.83 +/- 0.2 meq/min, and urine flow rate (V) from 13 +/- 1 to 24 +/- 3 ml/min (all P < 0.01 vs. baseline). At 15 min during infusion of ET, the GFR was not affected (2.1 +/- 0.1 to 2.2 +/- 0.1 ml/min) but modestly decreased to 1.8 +/- 0.1 ml/min at 30 min (P < 0.05 vs. baseline). Either removing the capsule from both kidneys during surgery or maintaining renal arterial pressure at baseline values with an adjustable clamp on the aorta above the right renal artery abolished the ET-induced increase in UNa V and V. Meclofenamate also did not alter the ET-induced increase in MAP, V, or UNa V. To determine the intrarenal site of action of ET, experiments were conducted with ET plus amiloride or with a combination of amiloride plus furosemide; there was a larger ET-induced diuresis and natriuresis in amiloride-treated rats and an even larger response with amiloride plus furosemide compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)