Evaluation of the association between a single-nucleotide polymorphism of bone morphogenetic proteins 5 gene and risk of knee osteoarthritis.

BACKGROUND: Osteoarthritis (OA) is a chronic degenerative disorder probably affected by both genetic and environmental causes. Bone morphogenetic proteins (BMPs) are bone-derived factors that can induce new bone formation. Single-nucleotide polymorphisms (SNPs) of BMP5 gene alters the transcriptional activity of the BMP5 promoter that has been involved in OA susceptibility. This case-control study investigated the association of rs1470527 and rs9382564 SNP of BMP5 gene with susceptibility to knee OA (KOA). MATERIALS AND METHODS: A total of 499 cases with radiographic KOA and 458 age- and sex-matched healthy controls were enrolled. Venous blood samples were obtained from all the cases as well as controls for polymerase chain reaction-restriction fragment length polymorphism. RESULTS: The genotype distribution for rs1470527 and rs9382564 SNP was significantly different in cases and controls (P < 0.0001). Within both the SNPs of BMP5 gene, genotype CT and TT were significantly (P < 0.0001) associated with KOA as compared to the CC genotype. T allele of both the studied SNP was significantly associated with KOA (P < 0.0001). The allele frequencies of rs1470527 were 0.56(T) and 0.44(C) in cases and 0.33(T) and 0.67(C) in controls and in rs9382564 were 0.57(C) and 0.43(T) in cases and 0.71(C) and 0.29(T) in controls. Further in relation with clinical severity of OA, we observed signification association of TT genotype with both visual analog scale (P < 0.0001) and Western Ontario and McMaster Universities score (P < 0.05). CONCLUSION: Our results indicate significant association of rs1470527 and rs9382564 polymorphism of BMP5 gene with KOA.

Draft genome sequence of Pontibacter sp. nov. BAB1700, a halotolerant, industrially important bacterium.

Pontibacter sp. nov. BAB1700 is a halotolerant, Gram-negative, rod-shaped, pink-pigmented, menaquinone-7-producing bacterium isolated from sediments of a drilling well. The draft genome sequence of the strain, consisting of one chromosome of 4.5 Mb, revealed vital gene clusters involved in vitamin biosynthesis and resistance against various metals and antibiotics.

Electron-phonon relaxation in disordered two-dimensional electron gas with dynamically screened deformation potential.

We study the effect of a dynamically screened deformation potential on the electron longitudinal phonon relaxation in a disordered two-dimensional electron gas. On consideration of the dynamic dielectric function and polarization operator, and the frequency ω dependence, we find a significant change in the temperature exponent as well as the pre-factor α from the earlier reported approximate temperature power law dependence αT(4) obtained under static strong screening and impurity limit. More strikingly, a reversal in the character of the dependence of scattering rate on the mean free path takes place on the incorporation of dynamic screening, where the behaviour changes from the static 1/l to the dynamic l(2) at T = 1.0 K and l = 10 nm.

Experimental detection of iron overload in liver through neutron stimulated emission spectroscopy.

Iron overload disorders have been the focus of several quantification studies involving non-invasive imaging modalities. Neutron spectroscopic techniques have demonstrated great potential in detecting iron concentrations within biological tissue. We are developing a neutron spectroscopic technique called neutron stimulated emission computed tomography (NSECT), which has the potential to diagnose iron overload in the liver at clinically acceptable patient dose levels through a non-invasive scan. The technique uses inelastic scatter interactions between atomic nuclei in the sample and incoming fast neutrons to non-invasively determine the concentration of elements in the sample. This paper discusses a non-tomographic application of NSECT investigating the feasibility of detecting elevated iron concentrations in the liver. A model of iron overload in the human body was created using bovine liver tissue housed inside a human torso phantom and was scanned with a 5 MeV pulsed beam using single-position spectroscopy. Spectra were reconstructed and analyzed with algorithms designed specifically for NSECT. Results from spectroscopic quantification indicate that NSECT can currently detect liver iron concentrations of 6 mg g(-1) or higher and has the potential to detect lower concentrations by optimizing the acquisition geometry to scan a larger volume of tissue. The experiment described in this paper has two important outcomes: (i) it demonstrates that NSECT has the potential to detect clinically relevant concentrations of iron in the human body through a non-invasive scan and (ii) it provides a comparative standard to guide the design of iron overload phantoms for future NSECT liver iron quantification studies.

Neutron stimulated emission computed tomography: a Monte Carlo simulation approach.

A Monte Carlo simulation has been developed for neutron stimulated emission computed tomography (NSECT) using the GEANT4 toolkit. NSECT is a new approach to biomedical imaging that allows spectral analysis of the elements present within the sample. In NSECT, a beam of high-energy neutrons interrogates a sample and the nuclei in the sample are stimulated to an excited state by inelastic scattering of the neutrons. The characteristic gammas emitted by the excited nuclei are captured in a spectrometer to form multi-energy spectra. Currently, a tomographic image is formed using a collimated neutron beam to define the line integral paths for the tomographic projections. These projection data are reconstructed to form a representation of the distribution of individual elements in the sample. To facilitate the development of this technique, a Monte Carlo simulation model has been constructed from the GEANT4 toolkit. This simulation includes modeling of the neutron beam source and collimation, the samples, the neutron interactions within the samples, the emission of characteristic gammas, and the detection of these gammas in a Germanium crystal. In addition, the model allows the absorbed radiation dose to be calculated for internal components of the sample. NSECT presents challenges not typically addressed in Monte Carlo modeling of high-energy physics applications. In order to address issues critical to the clinical development of NSECT, this paper will describe the GEANT4 simulation environment and three separate simulations performed to accomplish three specific aims. First, comparison of a simulation to a tomographic experiment will verify the accuracy of both the gamma energy spectra produced and the positioning of the beam relative to the sample. Second, parametric analysis of simulations performed with different user-defined variables will determine the best way to effectively model low energy neutrons in tissue, which is a concern with the high hydrogen content in biological tissue. Third, determination of the energy absorbed in tissue during neutron interrogation in order to estimate the dose. Results from these three simulation experiments demonstrate that GEANT4 is an effective simulation platform that can be used to facilitate the future development and optimization of NSECT.

Diabetic patients produce an increase in coronary sinus endothelin 1 after coronary artery bypass grafting.

Diabetes is associated with altered vascular responses, and diabetic patients demonstrate increased morbidity and mortality after coronary artery bypass grafting (CABG). We tested whether endothelin (ET)-1 levels in this patient population differed from those in nondiabetic subjects after CABG. Of 14 consecutive patients who underwent CABG by the same surgeon, 7 had type 2 diabetes and 7 were nondiabetic. The two groups did not differ significantly in preoperative ejection fraction, number of vessels bypassed, cross-clamp time, or Parsonnet's score. Coronary sinus blood samples were obtained before cardioplegic arrest and then obtained at 1 and 15 min after each of two reperfusion periods: reperfusion A (native coronary perfusion plus the left internal mammary artery), reperfusion B (saphenous vein graft perfusion). ET-1 was significantly increased at all reperfusion time points in diabetic patients compared with nondiabetic patients. In diabetic patients, reperfusion after CABG can trigger the release of ET-1, which may be a contributing factor in the increased cardiac morbidity seen in this patient population.

Splanchnic vascular control during sepsis and endotoxemia.

Endotoxemia and sepsis often result in circulatory derangements which manifest as perfusion maldistributions. It has been widely accepted that the splanchnic circulation decreases in perfusion during advanced septic or endotoxemic states. Impaired perfusion of splanchnic organs may result not only in organ dysfunction but also exacerbations of polymicrobial bacteremia due to intestinal mucosal leakage. Consequently, evaluation of the splanchnic mechanisms of vasoregulation and how perfusion is maintained is vital to any topic concerning the management of the septic patient.

Effect of aminoguanidine on plasma nitric oxide by-products and blood flow during chronic peritoneal sepsis.

We hypothesized that plasma nitric oxide (NO), generated via inducible NO synthase (iNOS) or endothelial constitutive NO synthase and measured via its by-products NO2- and NO3- (NO2- + NO3- = NOx) would increase and remain elevated during chronic peritoneal sepsis. We further hypothesized that treatment with aminoguanidine (AG; 50 mg/kg), a selective iNOS inhibitor, would decrease NO production and alter blood flow. Sprague Dawley rats were randomized to septic and nonseptic groups. Septic rats received an intraperitoneal cecal slurry (200 mg of cecal material/5 mL 5% dextrose-H2O/kg); control rats received sterile 5% dextrose-H2O (5 mL/kg) only. Plasma NOx and hemodynamics were measured 0, 4, 12, 24, and 48 h after sepsis or sham induction. We also examined the effect of AG, an iNOS inhibitor, on plasma NOx levels and tissue blood flow at 24 h. Septic rats uniformly displayed signs of sepsis, including lethargy, piloerection, and diarrhea. NOx levels were significantly elevated compared with controls at 4, 12, 24, and 48 h (p < or = .05). Septic rats also demonstrated hypotension (t = 12, 24, and 48 h) and tachycardia (t = 4, 12, 24, and 48 h). The infusion of AG (50 mg/kg intravenously for 30 min) at 24 h significantly decreased plasma NOx in septic animals. Plasma NOx concentrations returned to basal levels by 90 min after infusion of AG. In addition, blood flow studies demonstrated that AG treatment in nonseptic rats resulted in a significant decrease in blood flow to the stomach, skin, and adipose tissue, whereas AG infusion did not significantly alter the regional perfusion profile in septic animals. Furthermore, treatment with AG did not significantly alter mean arterial pressure in either group; however, nonseptic animals exhibited a decrease in stroke volume, and septic animals demonstrated an increase in heart rate. In contrast to the rise and fall of NOx levels in endotoxemia, this study demonstrates that the initial rise is sustained during 48 h of peritoneal sepsis. This sustained increase in NOx levels in this model correlated with the observable signs of systemic infection and may relate to enhanced iNOS activity. AG infusion demonstrated variable effects on regional tissue blood flow profiles in septic and nonseptic animals and attenuated the increase in plasma NOx levels in septic animals, an index of iNOS activity.

Effect of NG-nitro-L-arginine methyl ester on testicular blood flow and serum steroid hormones during sepsis.

Production of nitric oxide (NO) via NO synthase (NOS) has been implicated in the regulation of steroidogenesis in normal physiology and septic pathophysiology. The hypothesis that blockade of NOS by NG-nitro-L-arginine methyl ester (L-NAME) would affect testicular blood flow and circulating levels of steroid reproductive hormones was tested. Male Sprague-Dawley rats (350-450 g) were randomized to septic and nonseptic groups. Sepsis was induced with an intraperitoneal (i.p.) injection of a cecal slurry (200 mg/kg in 5 mL 5% dextrose in water (D5W)) in rats, while nonseptic rats received only sterile D5W. The rats (n = 6 per group) were catheterized in the jugular vein, left ventricle (via right carotid artery), and tail artery to determine blood flow and systemic hemodynamics and to collect blood at 24 h after induction of sepsis/sham sepsis. After baseline (24 h post-cecal slurry challenge) measurement, L-NAME (.50 mg/ kg x min) was infused through the jugular vein for 10 min, blood flow was determined using a radioactive microsphere technique, and blood samples were collected. The serum concentrations of corticosterone, progesterone, and testosterone were determined using radioimmunoassay. Plasma concentrations of NO byproducts (NOx) were determined using the Greiss reaction. After 24 h, heart rate, testicular blood flow, and NOx levels were significantly increased, whereas the serum concentration of testosterone was significantly decreased in the septic group as compared with the nonseptic group. However, serum concentrations of progesterone and corticosterone at 24 h after induction of sham-sepsis or sepsis were not statistically different. Infusion of L-NAME significantly reduced the testicular blood flow and serum NOx levels in septic rats as compared with their baseline values. The administration of L-NAME significantly increased the concentration of testosterone in nonseptic and septic rats as compared with their respective basal values. However, testosterone levels in septic rats were still significantly lower than in nonseptic rats. The results of this study indicate that the synthesis of NO through NO synthase may play a role in the regulation of testicular blood flow and the serum levels of testosterone, associated with chronic peritoneal sepsis in the rat.

Steroid hormone alterations following induction of chronic intraperitoneal sepsis in male rats.

The influence of sepsis on male reproductive function in chronic animal models has not been extensively investigated. On the basis of earlier clinical studies, it was hypothesized that chronic intraperitoneal (i.p.) sepsis in rats would modulate the circulating levels of steroid reproductive hormones. Male Sprague-Dawley rats (300-375 g) were randomized to septic and nonseptic groups. Sepsis was induced with cecal slurry (200 mg/kg/5 mL 5% dextrose in water (D5W); i.p.) in septic rats, while nonseptic rats received only sterile D5W. The rats (n = 8-12) were catheterized to measure systemic hemodynamics and to collect blood at 0, 12, 24, and 48 h after induction of sepsis/sham sepsis. A separate group of normal rats was included to serve as an unoperated control group. The plasma concentration of corticosterone, progesterone, and testosterone in serum was determined using radioimmunoassay. The heart rate was significantly increased at t = 12, 24, and 48 h following induction of sepsis. However, septic rats did not display any significant alterations in the mean arterial pressure and pulse pressure. Basal circulating concentrations of serum corticosterone, progesterone, and testosterone were 356 +/- 124 ng/mL, 2.37 +/- 1.03 ng/mL, and 1.88 +/- .29 ng/mL, respectively, in the unoperated rats. At t = 0 h there was a significant increase in the levels of corticosterone in septic rats and in the levels of progesterone in both septic and nonseptic rats. The elevations in the concentrations of corticosterone and progesterone returned to basal values after 24 and 48 h. The septic animals had significantly decreased levels of testosterone at t = 24 and 48 h as compared with basal values and nonseptic groups. Our model of sepsis produced a time-dependent decrease in levels of testosterone, an end product of male steroidogenesis. This, along with unchanged levels of corticosterone and progesterone at 24 and 48 h following sepsis, indicates that separate mechanisms for steroidogenesis regulating synthesis of these steroid hormones (progesterone and testosterone) occur with sepsis. It is concluded that in our chronic septic rat model, induction of i.p. sepsis produced dysfunction in steroidogenesis, which selectively affected the synthesis of testosterone.

Central versus peripheral mediation of naloxone's perfusion effects in endotoxic rats.

Opioid receptor antagonists can act centrally and peripherally. It is unclear if these 2 pathways differentially mediate the perfusion-associated effects of opioid antagonism during endotoxemia. Male, Sprague-Dawley rats (340-390 g) were surgically prepared with left ventricular, tail artery, and jugular vein catheters 24 h before experiments were begun. Conscious, unrestrained rats were challenged with Escherichia coli lipopolysaccharide (LPS; 2 mg/kg/hr over 30 min) infusion. Measurements of regional blood flows were made using radioactive microspheres prior to (baseline), and at 60 and 120 min after LPS infusion. Saline (1 mL/kg bolus + 0.5 mL/kg/h infusion), naloxone (Nlx; 4 mg/kg bolus + 2 mg/kg/h infusion), or naloxone methyl bromide (Nlx-mb; 4.64 mg/kg, bolus + 2.32 mg/kg/h infusion) were administered 40 min after LPS infusion was begun. Nlx-mb does not cross the blood-brain barrier, and was thus used to differentiate central from peripherally mediated responses. At the end of each experiment, blood samples were collected for determination of ET-1 and nitric oxide metabolites (NOx = NO3 + NO2) using enzyme-linked immunosorbent assay (ELISA) and Griess reaction methods, respectively. Endotoxemia produced a significant decrease in cardiac output and an increase in systemic vascular resistance. Treatment with Nlx or Nlx-mb significantly attenuated the endotoxin-induced elevation in systemic vascular resistance and the decrease in cardiac output at 60 min after induction of endotoxemia compared with their respective baseline values. Nlx and Nlx-mb also attenuated the endotoxin-induced increases in hepatic portal and skeletal vascular resistances. These observations suggested that the ameliorative effect of Nlx on endotoxemia-induced regional vascular resistance alterations was mediated via peripheral opioid receptor mechanisms. However, although Nlx attenuated the endotoxin-induced decreases in the blood flow to the stomach and pancreas, Nlx-mb attenuated the endotoxin-induced decreases in the blood flow to the small intestine and cecum, in addition to the pancreas and, to some extent, the stomach. As such, separate central and peripherally mediated actions of opioid receptor antagonism were indicated. Nlx also resulted in an increase in the plasma levels of ET-1 only, whereas Nlx-mb increased the plasma levels of ET-1 and NOx. These observations suggest that separate central and peripheral effects of opioids during endotoxemia play a role in the associated circulatory alterations, and may differentially affect the release and/or synthesis of vasoactive mediators that might be related to their varied hepatosplanchnic vascular response during endotoxemia.

Sepsis produces depression of testosterone and steroidogenic acute regulatory (StAR) protein.

The hypothesis that induction of chronic peritoneal sepsis would produce depression of serum testosterone due to a decrease in Leydig cell steroidogenic acute regulatory (StAR) protein or P450c17 steroidogenic enzyme was tested. Male Sprague-Dawley rats (350-400 g) were randomized to septic and nonseptic groups. Sepsis was induced with a cecal slurry (200 mg/kg in 5 mL of 5% dextrose in water (D5W); intraperitoneal) while nonseptic rats received only sterile D5W. Animals (n = 6, in each group) were killed by CO2 asphyxiation and blood samples were collected by direct cardiac puncture at 24 h after induction of sepsis/sham sepsis. The serum concentration of corticosterone, progesterone, estradiol, and testosterone was determined using radioimmunoassay. Western blot analysis was utilized to quantify Leydig cell StAR protein and P450c17 enzyme. Sepsis produced a significant decrease in the serum concentration of testosterone, a down-regulation of StAR protein, and an increase in serum estradiol 24 h after induction of sepsis (as compared with the nonseptic group). Protein levels of P450c17 in Leydig cells and serum concentrations of progesterone and corticosterone 24 h after induction of sham sepsis or sepsis were not different. It is concluded that the decreases in serum testosterone after 24 h of chronic peritoneal sepsis correlated with reductions in StAR protein.

Elevated coronary endothelin-1 but not nitric oxide in diabetics during CABG.

BACKGROUND: After coronary artery bypass grafting procedures, a higher incidence of morbidity and mortality has been reported in diabetic patients. We tested whether coronary artery bypass grafting in diabetics affects the endothelin-1 and nitric oxide coronary effluent profile during reperfusion. METHODS: Twenty-one consecutive patients (9 with type II diabetes mellitus, 12 non-diabetics) underwent coronary artery bypass grafting by one surgeon. The two groups did not differ in preoperative ejection fraction, Parsonnet score, number of vessels bypassed, or cross-clamp time. Each patient was treated in the same intraoperative manner with single atrial, aortic, and antegrade and retrograde cardioplegia (CPL) cannulas. Cold CPL arrest was by antegrade and retrograde infusion of modified Buckberg CPL solution. Warm CPL solution was infused before reperfusion. Coronary sinus blood samples were obtained for estimation of endothelin-1 and nitrite plus nitrate before CPL arrest and at 1 and 15 minutes after each of 2 reperfusion periods. RESULTS: In diabetics, endothelin-1 was significantly increased at all reperfusion times as compared with non-diabetics. Nitrite plus nitrate levels were significantly higher in patients with diabetes than in those without, but did not change with time in either of the groups. CONCLUSIONS: Reperfusion after CPL during coronary artery bypass grafting procedure can trigger the release of endothelin-1 in patients with diabetes mellitus. This may favor increased vascular tone or positive inotropic responses after coronary artery bypass grafting and may contribute to significant cardiovascular consequences in diabetic patients.

Evaluation of learning and memory mechanisms employing elevated plus-maze in rats and mice.

1. The effect of drugs affecting learning and memory was investigated using transfer latency (TL) as parameter for acquisition and retention of memory process on elevated plus-maze both in rats and mice. Further the validity of the procedure was envisaged. 2. The results provide an evidence for utility of shortened TL on 2nd day trial in old rats and mice as a parameter for retention or consolidation of memory, while treatment of drugs 30 min prior to 1st day may also be utilised for acquisition related action of drugs. 3. The drugs producing acquisition deficits namely scopolamine (0.1-0.5 mg/kg) and MK 801 (0.05-0.1 mg/kg) did not affect the shortened TL on elevated plus-maze in rats while nootropics, like piracetam (150 mg/kg) and captopril (30 mg/kg) reduced the shortened TL. The memory enhancing effect of these agent was reversed by scopolamine (0.3 mg/kg) and MK 801 (0.1 mg/kg) both in rats and mice. The results suggested the acquisition affecting drugs, however, did not show any effect on retention parameter (shortened TL) but can reverse the retention facilitatory action of nootropics. The results also provide indirect evidence for participation of cholinergic and NMDA-receptor blockade in the mechanism of these drugs. 4. Scopolamine and MK 801 produced acquisition deficits in mice, as they increased the TL on 1st and 2nd day trial while physostigmine (0.05 mg/kg) decreased the 2nd day TL. Physostigmine (0.1 mg/kg) reversed scopolamine and MK 801 induced acquisition deficits suggested participation of cholinergic and NMDA- receptor in learning process. 5. The results validate the utility of the elevated plus-maze for evaluation of possible nootropic action of drugs.

Prazosin blocks the pressor but not the regional circulatory effects of diaspirin crosslinked hemoglobin.

Diaspirin crosslinked hemoglobin (DCLHb) (400 mg/kg, i.v.) produces an increase in blood pressure and blood flow to the heart, spleen, stomach, small intestine, skin, mesentery and pancreas when administered to rats. The present study was conducted to determine (1) whether prazosin, an alpha 1-adrenergic antagonist, can block the pressor effect of DCLHb and (2) the effect of prazosin pretreatment on regional circulatory changes induced by DCLHb in rats. DCLHb (400 mg/kg, i.v.) produced an increase in blood pressure (64%), cardiac output (20%) and total peripheral resistance (65%) when administered to control rats. Infusion of DCLHb in prazosin (1 mg/kg, i.v.) treated rats did not show any significant pressor effect, but reversed the hypotensive effect of prazosin. Cardiac output and stroke volume were significantly increased and total peripheral resistance decreased in prazosin treated rats as compared to control (untreated) rats. DCLHb significantly increased blood flow to the heart, gastrointestinal tract, portal system (spleen), and skin of control rats. Blood flow to the brain, kidneys, and musculo-skeletal system was not altered following the infusion of DCLHb in controls rats. Infusion of DCLHb in prazosin treated rats produced a significant increase in blood flow to the brain, heart, kidneys, gastrointestinal tract, portal system, skin and musculoskeletal system. In summary, prazosin pretreatment blocked the pressor effect of DCLHb, however, blood flow to the heart, brain, gastrointestinal tract, portal system, kidneys, skin and musculoskeletal system was increased by DCLHb. It is concluded that blood flow to most of the organs is increased by DCLHb but the pressor effect of DCLHb is blocked by prazosin pretreatment.

Effect of stroma-free hemoglobin and diaspirin cross-linked hemoglobin on the regional circulation and systemic hemodynamics.

The effects of unmodified stroma-free hemoglobin (SFHb) and diaspirin cross-linked hemoglobin (DCLHb) on the regional blood circulation and systemic hemodynamics were studied in rats using a radioactive microsphere technique. SFHb and DCLHb increased mean arterial blood pressure without affecting heart rate. SFHb produced a 24.9% decrease in the cardiac output while DCLHb produced an 44.8% increase in the cardiac output. Stroke volume was decreased (-27.3%) by SFHb and increased (+36.4%) by DCLHb. Total peripheral resistance increased with both SFHb and DCLHb. DCLHb increased blood flow to the heart, spleen, stomach, small intestine and skin, and had no effect on blood flow to the brain, kidneys, liver, mesentery, pancreas, caecum, large intestine and musculo-skeletal system. In contrast, in animals infused with SFHb, blood flow decreased to the kidneys, liver and spleen, increased to the heart, small intestine and skin, and had no effect to the brain, caecum, large intestine and musculo-skeletal system. DCLHb had no effect on vascular resistance in any organ except for an increase in the musculo-skeletal system. In contrast, SFHb increased vascular resistance in the kidneys, liver, spleen, skin, mesentery and pancreas, and had no effect on vascular resistance in the musculo-skeletal system, brain, heart, stomach, small intestine, caecum and large intestine. SFHb had no effect on distribution of cardiac output to the brain, gastrointestinal tract (GIT), kidneys, skin, musculo-skeletal and portal system, while DCLHb significantly decreased the percent cardiac output to the musculo-skeletal system. DCLHb did not affect the distribution of cardiac output to the brain, GIT, kidneys, skin and portal system. SFHb and DCLHb increased the percent cardiac output to the heart. It is concluded that similar concentrations and doses of DCLHb and SFHb produce different effects on the regional blood circulation and systemic hemodynamics.

Renal endothelin mechanism in altered thyroid states.

Endothelin (ET) mechanisms were studied in hyper- and hypo-thyroid states in rats. Hyperthyroidism was induced by daily administration of thyroxine (0.1 mg/kg, i.p.) for 8 weeks, while hypothyroidism was induced by daily administration of methimazole (10 mg/kg, i.p.) for 8 weeks. The concentration of endogenous ET-1 was determined in the kidneys using radioimmunoassay. Systemic hemodynamics and renal blood circulation was measured using a radioactive microsphere technique. A significant increase in systolic and diastolic blood pressure, heart rate and cardiac output was observed in hyperthyroid rats as compared to eu- and hypo-thyroid rats. Total peripheral resistance was found to be similar in eu-, hyper- and hypo-thyroid rats. The endogenous concentration of ET-1 in the kidneys was significantly lower in hyper- as compared to eu- and hypo-thyroid rats. The blood flow to the kidneys was significantly increased in hyper- as compared to eu- and hypo-thyroid rats. Infusion of ET-1 (100 ng/kg/min i.v. for 45 min) produced a significant decrease in blood flow to the kidneys of eu-, hyper- and hypo-thyroid rats. The decrease in blood flow was similar in eu-, hyper- and hypo-thyroid rats, indicating that the response of renal blood vessels to exogenous ET-1 is not altered during thyroid dysfunction. Since endogenous ET-1 is involved in the regulation of vascular tone, it may be concluded that in hyper-thyroid rats decrease in concentration of the renal ET-1 could be contributing to an increase in blood flow to the kidney.

Effect of diaspirin crosslinked and stroma-reduced hemoglobin on mean arterial pressure and endothelin-1 concentration in rats.

The effect of unmodified stroma reduced (SRHb) and modified diaspirin crosslinked (DCLHb) hemoglobin solutions on the mean arterial pressure and endothelin-1 (ET-1) concentration in blood plasma and various tissues was studied. Infusion of DCLHb or SRHb increased mean arterial blood pressure by 96% and 39%, respectively. Heart rate was not significantly affected by DCLHb or SRHb. A significant increase (P < 0.003) in the ET-1 levels in blood plasma after DCLHb and SRHb infusion was observed. The increase in plasma ET-1 concentration was significantly more marked with SRHb (141%) as compared to DCLHb (78%) treated rats. The concentration of ET-1 in the heart and brain regions was not altered in DCLHb or SRHb treated rats as compared to control. However, ET-1 concentration was significantly increased in the thoracic aorta (151%) and renal medulla (272%) of DCLHb treated rats. SRHb treated rats also showed a significant increase in ET-1 concentration in the thoracic aorta (141%) and renal medulla (429%). The effect of SRHb on the renal medulla was found to be significantly greater than that of DCLHb. ET may be one of the factors responsible for the cardiovascular effects of hemoglobin solutions.

A differential response of diffuse brain injury on the concentrations of endothelin and nitric oxide in the plasma and brain regions in rats.

In the present study, we hypothesized that acute diffuse brain injury (DBI) in rats would produce an increase in endothelin-1 (ET-1), a potent vasoconstrictor, and/or nitric oxide (NO), a potent vasodilator, in plasma and brain areas in rats. DBI was induced in anesthetized male Sprague-Dawley rats (350-400 g) using a 350 g weight dropped from 1 meter height impact through a device designed by Marmarou et al., 1994. Blood plasma and brain tissue (cerebral cortex, diencephalon and brain stem) samples were collected for estimation of ET-1 and NO at zero or 6 h from rats (n = 6) subjected to DBI as well as control rats (n = 6), i.e., not subjected to DBI. In a separate group of animals, cerebral blood flow (CBF) was recorded at 0, 5, 10, 15, 30, 60, 120, 240 and 360 min after induction of DBI or sham-DBI. Acute DBI produced a significant decrease in CBF at 120 min after induction of DBI. Plasma levels of ET-1 was found to be significantly increased (from 0.89 +/- 0.09 to 2.09 +/- 0.29 pg ml-1), at 6 h following DBI. DBI produced a significant decrease in the levels of ET-1 in diencephalon (from 70.97 +/- 9.47 to 57.64 +/- 2.65 pg g-1). In contrast to ET-1, DBI produced a significant increase in the concentrations of NO in the diencephalon, cerebral cortex and brain stem at 6 h post DBI. It appears that DBI-induced increase in the levels of NO in brain regions which might be down regulating the synthesis of ET-1 in diencephalon. It is concluded that ET and NO homeostatic mechanisms may play a role in the regional and vascular responses associated with acute DBI.

Evidence for GABA-BZ receptor modulation in short-term memory passive avoidance task paradigm in mice.

The possible involvement of gamma-aminobutyric acid/benzodiazepine (GABA-BZ) receptor modulation in scopolamine-induced short-term memory deficit was investigated in mice. Passive avoidance step-down task behavior was observed. Latency of mice to reach shock-free zone (SFZ) and number of mistakes the animal made in 15 min were used as separate parameters for acquisition and memory retention, respectively. Scopolamine (0.3 mg/kg) caused a delay in reaching SFZ and an increased number of mistakes. Physostigmine reversed the scopolamine-induced increase in number of mistakes; however, it caused a delay in the time to reach SFZ. Subeffective dose of GABA, when combined with physostigmine, further delayed the latency to reach SFZ, but reduced the number of mistakes very significantly. GABA (50, 75 and 100 mg/kg, i.p.) and GABA agonists sodium valproate (30 and 60 mg/kg, i.p.), fengabine (5 and 10 mg/kg, i.p.), (+/-)baclofen (0.25, 0.5 and 1.0 mg/kg, i.p.) and (-)baclofen (0.25 and 0.5 mg/kg i.p.) reversed the scopolamine-induced effect; however, sodium valproate at higher dose delayed time to reach SFZ. Combined administration of lower dose (+/-)baclofen and subeffective dose of GABA showed significant decrease in latency and number of mistakes in scopolamine-treated animals. The specific benzodiazepine antagonist flumazenil (Ro-15-1788) (5 and 10 mg/kg, i.p.) and inverse agonist FG-7142 (10 mg/kg, i.p.) very significantly reversed scopolamine-induced increase in number of mistakes, but Ro-15-1788 failed to show any effect on latency per se and in scopolamine-treated experiments, as well.(ABSTRACT TRUNCATED AT 250 WORDS)