Mechanism of Preconditioning by Isoflurane in Rabbits: A Direct Role for Reactive Oxygen Species

Background: Reactive oxygen species (ROS) contribute to myocardial protection during ischemic preconditioning, but the role of the ROS in protection against ischemic injury produced by volatile anesthetics has only recently been explored. We tested the hypothesis that ROS mediate isoflurane-induced preconditioning in vivo.

Methods: Pentobarbital-anesthetized rabbits were instrumented for measurement of hemodynamics and were subjected to a 30 min coronary artery occlusion followed by 3 h reperfusion. Rabbits were randomly assigned to receive vehicle (0.9% saline), or the ROS scavengers N-acetylcysteine (NAC; 150 mg/kg) or N-2-mercaptopropionyl glycine (2-MPG; 1 mg [middle dot] kg-1[middle dot] min-1), in the presence or absence of 1.0 minimum alveolar concentration (MAC) isoflurane. Isoflurane was administered for 30 min and then discontinued 15 min before coronary artery occlusion. A fluorescent probe for superoxide anion production (dihydroethidium, 2 mg) was administered in the absence of the volatile anesthetic or 5 min before exposure to isoflurane in 2 additional groups (n = 8). Myocardial infarct size and superoxide anion production were assessed using triphenyltetrazolium staining and confocal fluorescence microscopy, respectively.

Results: Isoflurane (P < 0.05) decreased infarct size to 24 +/- 4% (mean +/- SEM; n = 10) of the left ventricular area at risk compared with control experiments (43 +/- 3%; n = 8). NAC (43 +/- 3%; n = 7) and 2-MPG (42 +/- 5%; n = 8) abolished this beneficial effect, but had no effect on myocardial infarct size (47 +/- 3%; n = 8 and 46 +/- 3; n = 7, respectively) when administered alone. Isoflurane increased superoxide anion production as compared with control experiments (28 +/- 12 vs. -6 +/- 9 fluorescence units;P < 0.05).     

Reactive Oxygen Species Play a Biphasic Role in Brain Ischemia

Objective: Reactive oxygen species (ROS) are the essential mechanism involving in the ischemic process. Due to their complex characteristics, the precise effects of ROS on post-ischemic neurons remain uncertain. This study aimed to investigate the potential role of ROS in brain ischemia. Methods: Dynamic ROS levels in the perifocal cortex were evaluated after right middle cerebral artery occlusion (MCAO) of SD rats. Furthermore the role of ROS was assessed following delayed treatment with the ROS scavenger dimethylthiourea (DMTU) after brain ischemia. Results: ROS levels markedly increased at 1 hr after reperfusion and then gradually decreased as the post-reperfusion time interval increased. ROS levels reached their lowest point at 3 days after reperfusion before increasing and showing a second peak at 7 days after reperfusion. ROS levels negatively correlated with neurological function scores. Delayed DMTU treatment after stroke worsened neurological outcomes, decreased microvessel density and inhibited stress-activated protein kinase activation. Conclusion: ROS may play a biphasic role in cerebral ischemia. Namely, ROS may induce damage during the injury phase of brain ischemia and participate in improving neurological function during the recovery phase.     

Anatomical Locations of Human Brown Adipose Tissue: Functional Relevance and Implications in Obesity and Type 2 Diabetes

We will review information about and present hypotheses as to the anatomy of brown adipose tissue (BAT). Why is it located where it is in humans? Its anatomical distribution is likely to confer survival value by protecting critical organs from hypothermia by adaptive thermogenesis. Ultimately, the location and function will be important when considering therapeutic strategies for preventing and treating obesity and type 2 diabetes, in which case successful interventions will need to have a significant effect on BAT function in subjects living in a thermoneutral environment. In view of the diverse locations and potential differences in responsiveness between BAT depots, it is likely that BAT will be shown to have much more subtle and thus previously overlooked functions and regulatory control mechanisms.Until ~10 years ago, brown adipose tissue (BAT) was considered to be biologically active in neonates and young children generating heat during cold exposure by adaptive thermogenesis to maintain normal body temperature (1). BAT regressed with aging by transforming into white adipose tissue (WAT) (2), and BAT in adults was not considered important in energy metabolism (1,3). At that time, reports in the nuclear medicine literature surfaced that ¹⁸F-fluorodeoxyglucose (FDG), an intravenously administered radioactive glucose analog taken up but not metabolized by neoplasms and used to delineate metastatic cancers in positron emission tomography (PET) scans, also localized in adipose tissues pinpointed by concomitant computed tomography (CT) (PET-CT fusion) scans to be commensurate with BAT and in most instances not with tumor tissue (4,5). It was therefore demonstrated that the main BAT depot was within the supraclavicular region, although as detailed below a number of perhaps less important depots were identified (6–11). Because more attention has been given to the physiology (6–9), pathophysiology (6), and clinical characteristics (10,11) of human BAT rather than its anatomy, the purpose of this Perspective is to review information about and to consider hypotheses why BAT is located where it is in humans as well as the functional relevance and therapeutic implications of its locations.     

Impact of Physical Inactivity on Subcutaneous Adipose Tissue Metabolism in Healthy Young Male Offspring of Patients With Type 2 Diabetes

OBJECTIVE

Physical inactivity is a risk factor for type 2 diabetes and may be more detrimental in first-degree relative (FDR) subjects, unmasking underlying defects of metabolism. Using a positive family history of type 2 diabetes as a marker of increased genetic risk, the aim of this study was to investigate the impact of physical inactivity on adipose tissue (AT) metabolism in FDR subjects.

RESEARCH DESIGN AND METHODS

A total of 13 FDR and 20 control (CON) subjects participated in the study. All were studied before and after 10 days of bed rest using the glucose clamp technique combined with measurements of glucose uptake, lipolysis, and lactate release from subcutaneous abdominal (SCAAT) and femoral (SCFAT) adipose tissue by the microdialysis technique. Additionally, mRNA expression of lipases was determined in biopsies from SCAAT.

RESULTS

Before bed rest, the FDR subjects revealed significantly increased glucose uptake in SCAAT. Furthermore, mRNA expression of lipases was significantly decreased in the SCAAT of FDR subjects. Bed rest significantly decreased lipolysis and tended to increase glucose uptake in the SCFAT of both CON and FDR subjects. In response to bed rest, SCAAT glucose uptake significantly increased in CON subjects but not in FDR subjects.

CONCLUSIONS

FDR subjects exhibit an abnormal AT metabolism including increased glucose uptake prior to bed rest. However, the differences between FDR and CON subjects in AT metabolism were attenuated during bed rest due to relatively more adverse changes in CON subjects compared with FDR subjects. Physical inactivity per se is not more deleterious in FDR subjects as compared with CON subjects with respect to derangements in AT metabolism.Type 2 diabetes is the product of a complex interplay between genetic susceptibility and environmental factors. The best known environmental modifiable risk factors for type 2 diabetes are obesity and a low level of habitual physical activity (1).Even though there is substantial evidence that a change toward a healthy lifestyle halts the progression of type 2 diabetes (2), certain groups, including first-degree relatives (FDRs) of patients with type 2 diabetes, are at increased risk of developing the disease (3). Type 2 diabetes has a major hereditary component (4), and FDR subjects show multiple abnormalities in intermediary metabolism and pancreatic islet cell function, displaying insulin resistance despite normal glucose tolerance (5). The metabolic defects include insufficient insulin secretion (6), decreased peripheral glucose uptake (7), and the impaired antilipolytic effect of insulin in subcutaneous adipose tissue (AT) (8).AT is an active compartment in the lipid and glucose metabolism of humans, but the role of AT metabolism in the development of type 2 diabetes is not clarified. AT, along with skeletal muscle, is a site of peripheral insulin resistance in type 2 diabetes (9). The role of AT in the pathophysiology of insulin resistance can partly be attributed to lipolytic activity resulting in the mobilization of free fatty acids (FFAs), which are deleterious for glucose utilization and insulin action (10). However, AT may play a more direct role since it is a site of deranged glucose metabolism. Although AT is of minor quantitative importance for whole-body glucose disposal, the tissue produces lactate (11), which functions as a gluconeogenic precursor in the liver (12). Previous studies have demonstrated increased plasma lactate (13) and lactate release from adipocytes (14) in FDR subjects.In this study, we investigated in vivo AT glucose uptake, lipolysis, and lactate release, as well as subcutaneous abdominal adipose tissue (SCAAT) mRNA expression of lipases and GLUT-4 in FDR and control (CON) subjects prior to and after 10 days of bed rest. We hypothesized that FDR subjects would show abnormalities in baseline AT metabolism and be more sensitive to the unhealthy effects of physical inactivity.     

Urinary Adiponectin Excretion: A Novel Marker for Vascular Damage in Type 2 Diabetes

OBJECTIVE

Markers reliably identifying vascular damage and risk in diabetic patients are rare, and reports on associations of serum adiponectin with macrovascular disease have been inconsistent. In contrast to existing data on serum adiponectin, this study assesses whether urinary adiponectin excretion might represent a more consistent vascular damage marker in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Adiponectin distribution in human kidney biopsies was assessed by immunohistochemistry, and urinary adiponectin isoforms were characterized by Western blot analysis. Total urinary adiponectin excretion rate was measured in 156 patients with type 2 diabetes who had a history of diabetic nephropathy and 40 healthy control subjects using enzyme-linked immunosorbent assay. Atherosclerotic burden was assessed by common carotid artery intima-media-thickness (IMT).

RESULTS

A homogenous staining of adiponectin was found on the endothelial surface of glomerular capillaries and intrarenal arterioles in nondiabetic kidneys, whereas staining was decreased in diabetic nephropathy. Low-molecular adiponectin isoforms (∼30–70 kDa) were detected in urine by Western blot analysis. Urinary adiponectin was significantly increased in type 2 diabetes (7.68 ± 14.26 vs. control subjects: 2.91 ± 3.85 μg/g creatinine, P = 0.008). Among type 2 diabetic patients, adiponectinuria was associated with IMT (r = 0.479, P < 0.001) and proved to be a powerful independent predictor of IMT (β = 0.360, P < 0.001) in multivariable regression analyses. In a risk prediction model including variables of the UK Prospective Diabetes Study coronary heart disease risk engine urinary adiponectin, but not the albumin excretion rate, added significant value for the prediction of increased IMT (P = 0.007).

CONCLUSIONS

Quantification of urinary adiponectin excretion appears to be an independent indicator of vascular damage potentially identifying an increased risk for vascular events.Cardiovascular disease (CVD) is the leading cause of mortality in patients with type 2 diabetes, and the identification of individual risk patterns is fundamental for the prevention and treatment of CVD. However, risk stratification in patients with diabetes is still vague (1,2), and, consequently, numbers needed to treat for prevention of a single cardiovascular event in clinical trials are ∼100–200 patients per year (3–5).Most of the recently described risk markers are metabolic or inflammatory molecules that do not directly indicate vascular damage. Therefore, these indirect markers show variations in risk prediction depending on the metabolic status of the study group (6,7). This becomes evident reviewing data on serum adiponectin; whereas low-circulating adiponectin was significantly associated with increased primary CVD risk in apparently healthy men (8), subsequent studies in high-risk populations, as well as patients with prevalent coronary heart disease (CHD), failed to confirm this association (9,10). A reason for this discrepancy between different groups of risk patients could be a reverse causality, where silent or apparent CVD might lead to compensatory rises in serum adiponectin. Consistently, it was shown in type 2 diabetic patients that adiponectin is lowest in the presence of impaired glucose regulation and early diabetes, whereas long diabetes duration is associated with a significant increase in circulating adiponectin (11).Adiponectin is a 30-kDa adipocyte-derived vasoactive peptide closely linked to components of the metabolic syndrome (rev. in 12). It has anti-inflammatory and antiatherosclerotic properties on endothelial cells by decreasing vascular inflammation, foam cell formation, and cell adhesion, which all are involved in the initiation and progression of vascular lesions (12). Recently, it was reported that adiponectin has a distinct role for glomerular homeostasis in an experimental model (13). Hence, adiponectin could be present on human renal endothelium and glomerular capillary stress in diabetes may promote shedding of adiponectin from endothelial surfaces by proteolytic cleavage, causing degradation of high-order complexes of adiponectin and subsequent appearance of the adiponectin monomer (∼28 kDa), dimer (∼56 kDa), and trimer (∼68 kDa) in urine.We hypothesized that adiponectin appears in urine consequently reflecting early glomerular vascular damage in type 2 diabetes rather than the metabolic changes associated with serum adiponectin. To characterize a possible diagnostic value of urinary adiponectin excretion, patients with type 2 diabetes and early diabetic nephropathy (i.e., a history of microalbuminuria) were studied, and the atherosclerotic burden of these patients was assessed by quantification of common carotid artery intima-media-thickness (IMT). Both urinary adiponectin and urinary albumin excretion rate (AER) as an established marker of micro- and macrovascular dysfunction in type 2 diabetes were evaluated for the prediction of increased IMT in comparative analyses.     

Source of Reactive Oxygen Species in Anti-Thy1 Nephritis

In proliferative glomerulonephritis, both macrophages and mesangial cells generate reactive oxygen species (ROS), contributing to the development of glomerular injury. We have attempted to determine which cell produces ROS during anti-Thyl nephritis (ATN) in rats. The generation of ROS was studied using lutninol amplified chemiluminescence (GCL) on isolated glomeruli. Immunohistochemical studies used avidin-biotin complex (ABC) to label macrophages and mesangial cells. Immediately after ATN induction, mesangiolysis and infiltration with ED-1 positive cells (referred to as macrophage) was noted with a peak at day 1. After day 4, mesangial proliferation appeared with a decrease of the ED-1 positive cells and a prominent increase of PCNA positive cells (regarded as mesangial cells). In the early phase of ATN, GCL, reflecting ROS generation, increased along with the appearance of ED-1 positive cells. GCL subsequently decreased as mesangial cells increased. This suggested that macrophage were the principal participants in ROS generation in the early phase of ATN although mesangial cells cannot be completely disregarded in the generation of ROS and development of glomerular injury.     

A Novel Role for Subcutaneous Adipose Tissue in Exercise-Induced Improvements in Glucose Homeostasis

Exercise training improves whole-body glucose homeostasis through effects largely attributed to adaptations in skeletal muscle; however, training also affects other tissues, including adipose tissue. To determine whether exercise-induced adaptations to adipose tissue contribute to training-induced improvements in glucose homeostasis, subcutaneous white adipose tissue (scWAT) from exercise-trained or sedentary donor mice was transplanted into the visceral cavity of sedentary recipients. Remarkably, 9 days post-transplantation, mice receiving scWAT from exercise-trained mice had improved glucose tolerance and enhanced insulin sensitivity compared with mice transplanted with scWAT from sedentary or sham-treated mice. Mice transplanted with scWAT from exercise-trained mice had increased insulin-stimulated glucose uptake in tibialis anterior and soleus muscles and brown adipose tissue, suggesting that the transplanted scWAT exerted endocrine effects. Furthermore, the deleterious effects of high-fat feeding on glucose tolerance and insulin sensitivity were completely reversed if high-fat–fed recipient mice were transplanted with scWAT from exercise-trained mice. In additional experiments, voluntary exercise training by wheel running for only 11 days resulted in profound changes in scWAT, including the increased expression of ∼1,550 genes involved in numerous cellular functions including metabolism. Exercise training causes adaptations to scWAT that elicit metabolic improvements in other tissues, demonstrating a previously unrecognized role for adipose tissue in the beneficial effects of exercise on systemic glucose homeostasis.     

Reactive Oxygen Species Production by the Spermatozoa of Patients With Idiopathic Infertility: Relationship to Seminal Plasma Antioxidants

Purpose

We attempted to determine reactive oxygen species production by the spermatozoa of patients with idiopathic infertility and healthy donors, and observe whether increased production was due to decreased seminal plasma reactive oxygen species scavengers.

Materials and Methods

Reactive oxygen species production by spermatozoa and seminal plasma antioxidants was assayed in 18 patients with idiopathic infertility and 10 controls. Reactive oxygen species formation and seminal plasma antioxidants were measured by luminol and lucigenin dependent chemoluminescence, and enzymatic methods, respectively.

Results

Higher reactive oxygen species production was observed in 16 of the 18 patients (88.8%, p <0.0001 versus controls). Seminal plasma superoxide dismutase, catalase, glutathione peroxidase and total sulfhydryl group levels in infertile patients were significantly lower than in controls.

Conclusions

Decreased seminal plasma antioxidant activity and increased reactive oxygen species production can be responsible for idiopathic male infertility.     

Inhibition of Reactive Oxygen Species by Lovastatin Downregulates Vascular Endothelial Growth Factor Expression and Ameliorates Blood-Retinal Barrier Breakdown in db/db Mice: Role of NADPH Oxidase 4

OBJECTIVE

Oxidative stress is a key pathogenic factor in diabetic retinopathy. We previously showed that lovastatin mitigates blood-retinal barrier (BRB) breakdown in db/db mice. The purpose of this study is to determine the mechanisms underlying the salutary effects of lovastatin in diabetic retinopathy.

RESEARCH DESIGN AND METHODS

Expression of NADPH oxidase (Nox) 4, vascular endothelial growth factor (VEGF), and hypoxia-inducible factor (HIF)-1α; production of reactive oxygen species (ROS); and retinal vascular permeability were measured in cultured retinal capillary endothelial cells (RCECs) and in db/db mice treated with lovastatin.

RESULTS

Expressions of Nox4 and VEGF were significantly increased in retinas of db/db mice and reduced by lovastatin treatment. In cultured RCECs, hypoxia and high glucose upregulated mRNA and protein expression of Nox4, ROS generation, and VEGF level. These changes were abrogated by pretreatment with lovastatin or NADPH oxidase inhibitor diphenyleneiodonium chloride. Overexpression of Nox4 increased basal level of ROS generation, HIF-1α, and VEGF expression in RCECs. In contrast, blockade of Nox4 activity using adenovirus-expressing dominant-negative Nox4 abolished hypoxia- and high-glucose–induced ROS production and VEGF expression. Moreover, inhibition of Nox4 attenuated hypoxia-induced upregulation of HIF-1α and high-glucose–elicited phosphorylation of STAT3. Finally, depletion of Nox4 by adenovirus-delivered Nox4 small interfering RNA significantly decreased retinal NADPH oxidase activity and VEGF expression and reduced retinal vascular premeability in db/db mice.

CONCLUSIONS

Activation of Nox4 plays an important role in high-glucose– and hypoxia-mediated VEGF expression and diabetes-induced BRB breakdown. Inhibition of Nox4, at least in part, contributes to the protective effects of lovastatin in diabetic retinopathy.Diabetic retinopathy is a common complication of diabetes and one of the most frequent causes of blindness in the U.S. (1–3). Hallmark sequential pathological changes in diabetic retinopathy include increased vascular permeability, pericyte and endothelial cell death, capillary occlusion and aberrant retinal new vessel growth, or neovascularization (4). Increased vascular permeability caused by the breakdown of the blood-retinal barrier (BRB) results in diabetic macular edema, a major cause of vision loss in diabetic patients (2,5,6). Vascular endothelial growth factor (VEGF) is a potent angiogenic factor playing a crucial role in angiogenesis (7,8). VEGF is also referred as vascular permeability factor (VPF) based on its ability to induce vascular hyperpermeability (9). Significantly elevated VEGF levels in the eye have been reported in diabetic patients with diabetic macular edema and correlated with the severity of vascular leakage (10). Overexpression of VEGF is also responsible for retinal hyperpermeability in streptozotocin (STZ)-induced diabetic rats (11). These findings suggest that VEGF is a key mediator of retinal vascular leakage in diabetic retinopathy.Oxidative stress plays an important role in vascular endothelial dysfunction in diabetes (12–15). Increased level of hydrogen peroxide, a reactive oxygen species (ROS), was colocalized with VEGF expression at the inner BRB and associated with vascular leakage in the retina in diabetic BBZ/Wor rats, suggesting a role of ROS in regulation of VEGF in diabetic retinopathy (16). In addition, suppression of ROS generation by NADPH oxidase inhibitor or antioxidants significantly attenuated retinal vascular leakage in diabetic animals, suggesting that activation of NADPH oxidase contributes to retinal ROS generation and vascular damage in diabetic retinopathy (17). NADPH oxidase (Nox) 4, which is originally identified in the kidney and termed renox (renal oxidase), is a novel isoform of NADPH oxidase expressed in nonphagocytes, such as vascular endothelial cells and smooth muscle cells (18,19). In aorta isolated from the STZ-induced diabetic apolipoprotein E–deficient mice or the db/db mice, Nox4 expression is significantly upregulated, associated with increased ROS production and inflammation, indicating a potential role of Nox4 in diabetic macrovascular disease (20). Moreover, inhibition of Nox4 expression using antisense oligonucleotides attenuates ROS generation and ameliorates glomerular hypertrophy in STZ-induced diabetic mice, suggesting that Nox4 is the major source of ROS in the diabetic kidney, contributing to renal hypertrophy in diabetic nephropathy (21). However, the role of Nox4 in diabetic retinopathy has not been investigated.3-Hydroxy-3-methylglutaryl CoA reductase inhibitors (statins) are potent inhibitors of cholesterol biosynthesis commonly used in dyslipidemia and type 2 diabetes (22). Moreover, statins have demonstrated impressive beneficial effects, such as improvement of endothelial function, neuroprotection, and anti-inflammation, which are independent of their lipid-lowering effects (23). In a previous study, we have shown that lovastatin protects retinal tight junction and ameliorates BRB breakdown in db/db mice, a type 2 diabetes model (24). However, the mechanisms remain elusive. In the present study, we have tested the hypothesis that Nox4 is a key mediator of oxidative stress and BRB breakdown in diabetic retinopathy and that inhibition of Nox4 is, at least in part, responsible for the salutary effect of lovastatin on retinal endothelial function.     

Emerging Aspects of the Body Composition,Bone Marrow Adipose Tissue and Skeletal Phenotypes in Type 1 Diabetes Mellitus

Anthropomorphic measures among type 1 diabetic patients are changing as the obesity epidemic continues. Excess fat mass may impact bone density and ultimately fracture risk. We studied the interaction between bone and adipose tissue in type 1 diabetes subjects submitted to two different clinical managements: (I) conventional insulin therapy or (II) autologous nonmyeloablative hematopoietic stem-cell transplantation (AHST). The study comprised 3 groups matched by age, gender, height and weight: control (C = 24), type 1 diabetes (T1D = 23) and type 1 diabetes treated with AHST (T1D-AHST = 9). Bone mineral density (BMD) and trabecular bone score (TBS) were assessed by dual X-ray absorptiometry (DXA). ¹H Magnetic resonance spectroscopy was used to assess bone marrow adipose tissue (BMAT) in the L3 vertebra, and abdominal magnetic resonance imaging was used to assess intrahepatic lipids (IHL), visceral (VAT) and subcutaneous adipose tissue (SAT). Individuals conventionally treated for T1D were more likely to be overweight (C = 23.8 ± 3.7; T1D = 25.3 ± 3.4; T1D-AHST = 22.5 ± 2.2 Kg/m²; p > 0.05), but there was no excessive lipid accumulation in VAT or liver. Areal BMD of the three groups were similar at all sites; lumbar spine TBS (L3) was lower in type 1 diabetes (p < 0.05). Neither SAT nor VAT had any association with bone parameters. Bone marrow adipose tissue (BMAT) lipid profiles were similar among groups. BMAT saturated lipids were associated with cholesterol, whereas unsaturated lipids had an association with IGF1. Overweight and normal weight subjects with type 1 diabetes have normal areal bone density, but lower trabecular bone scores. Adipose distribution is normal and BMAT volume is similar to controls, irrespective of clinical treatment.     

Sealing of a Fabric Vascular Prosthesis with Autologous Adipose Tissue: A Preliminary Report of Its Clinical Application

Abstract: A new method of sealing fabric vascular pros-theses with autologous adipose tissue was clinically applied as an alternative to preclotting with fresh blood. Thirty-six patients with peripheral arterial occlusive disease were implanted with highly porous fabric prostheses. The prostheses were prepared by sealing the fabric pores with autologous adipose tissue that had been chopped up into small pieces and enmeshed in the fabric by forceful injection of the tissue suspension through a syringe. There was no complication related to the sealed graft such as graft bleeding after implantation. In-hospital mortality occurred in 4 patients: 1 case each of pneumonia, pulmonary infarction, sepsis, and acute myocardial infarction. During the period of 274 ± 190 days, 3 pros-theses were found to be occluded. All the other grafts were patent. The overall patency rate was 91.4%. Postoperative angiography revealed neither intimai thickening at the anastomotic sites nor irregularity of the prosthetic surface. The method proved safe and useful for implantation of smaller caliber artificial grafts.     

The Significance of Testicular Reactive Oxygen Species on Testicular Histology in Infertile Patients

This study was designed to investigate the relationship between the effects of testicular reactive oxygen species (ROS) levels and testicular histology on infertile patients with the aid of xanthine oxidase system and testicular tissue malondialdehyde levels. Forty patients with idiopathic infertility constituted our study group. Bilateral testicular biopsies were performed and spermatogenesis was assessed histopathologically. Patients were divided into 4 groups according to spermatogenic pattern (normal spermatogenesis; hypospermatogenesis; maturation arrest; Sertoli cell only syndrome). Testicular tissue xanthine oxidase and malondialdehyde (MDA) concentrations were analyzed in each sample by spectrophotometric assay and thiobarbituric acid reaction assay, respectively. Testicular tissue MDA and xanthine oxidase concentrations were not statistically different in patients having normal spermatogenesis, with respect to Sertoli cell only syndrome, maturation arrest and hypospermatogenesis, respectively. As a result of our study we think that there are still some factors other than ROS which may be important contributors to spermatogenetic injury that need to be examined.     

Mycophenolic Acid Inhibits Platelet-Derived Growth Factor-Induced Reactive Oxygen Species and Mitogen-Activated Protein Kinase Activation in Rat Vascular Smooth Muscle Cells

Vascular smooth muscle cell (VSMC) proliferation is the major pathologic feature associated with chronic allograft nephropathy, and mycophenolic acid (MPA) inhibits VSMC proliferation. Since the role of inosine monophosphate dehydrogenase (IMPDH)-dependent de novo guanosine synthesis is limited in VSMCs, we examined the effects of MPA on platelet-derived growth factor (PDGF)-induced cellular ROS and mitogen-activated protein kinases (MAPK) activation in VSMCs. Primary cultured rat VSMCs were stimulated with PDGF-BB in the presence or absence of MPA. Cell proliferation was assessed by [3H]-thymidine incorporation, ROS by flow cytometry and MAPK activation by Western blot analysis. PDGF increased cell proliferation, cellular ROS and extracellular-regulated protein kinase (ERK) 1/2 and p38 MAPK activation by 3.4-, 1.6-, 3.3- and 3.9-fold, respectively. MPA at above 1 muM inhibited PDGF-induced cellular ROS and ERK 1/2 and p38 MAPK activation, as well as proliferation. Structurally different anti-oxidants and inhibitor of ERK or p38 MAPK blocked PDGF-induced proliferation. Anti-oxidants also inhibited ERK 1/2 and p38 MAPK activation. Exogenous guanosine partially recovered the inhibitory effect of MPA on VSMC proliferation. These results suggest that MPA may inhibit PDGF-induced VSMC proliferation partially through inhibiting cellular ROS, and subsequent ERK 1/2 and p38 MAPK activation in addition to inhibiting IMPDH.     

Roux-en-Y胃转流术对2型糖尿病大鼠血清vaspin表达的影响

目的研究Roux-en-Y胃转流术(RYGB)对2型糖尿病(T2DM)大鼠的治疗作用,并探讨内脏脂肪组织产生的丝氨酸蛋白酶抑制剂(vaspin)在RYGB治疗T2DM机制中的可能作用。方法取造模成功的T2DM大鼠20只和周龄、性别相匹配的正常SD大鼠20只,用随机数字表法将其随机分为T2DM-RYGB组、T2DM-假手术组及RYGB组、假手术组,每组10只。分别于术前及术后第4和8周检测各组大鼠的空腹血糖(FPG)、血清胰岛素(INS)、血清vaspin水平及胰岛素抵抗指数(HOMA-IR),并分析血清vaspin水平与FPG、INS及HOMA-IR的相关性。结果手术前,T2DM-RYGB组与T2DM-假手术组比较以及RYGB组与假手术组比较,FPG水平、INS水平、vaspin水平及HOMA-IR差异均无统计学意义(P>0.05);而T2DM-RYGB组及T2DM-假手术组的FPG水平、INS水平、vaspin水平及HOMA-IR均分别明显高于RYGB组(P<0.05)及假手术组(P<0.05)。术后第4周,T2DM-RYGB组FPG水平、INS水平、vaspin水平及HOMA-IR较术前下降,除FPG水平(P<0.05)外,其余指标与术前比较差异均无统计学意义(P>0.05);术后第8周,FPG水平、INS水平、vaspin水平及HOMA-IR进一步下降,与术前比较差异均有统计学意义(P<0.05)。T2DM-假手术组、RYGB组及假手术组组内术前及术后第4周、第8周FPG水平、INS水平、vaspin水平及HOMA-IR比较,差异均无统计学意义(P>0.05)。手术前及手术后第4周、第8周T2DM-RYGB组与T2DM-假手术组血清vaspin水平与其对应血清INS水平、HOMA-IR均呈正相关(P<0.05)。结论 RYGB对T2DM大鼠具有一定的治疗作用,RYGB后vaspin表达水平降低,胰岛素敏感性改善,这可能是RYGB治疗T2DM的机制之一。