Establishment of a cut‐point value of serum TNF‐α levels in the metabolic syndrome

Cardiovascular diseases and type 2 diabetes are the major causes of mortality in Mexico. Metabolic syndrome (MS) is a cluster of factors that increase the risk to develop such diseases. Previous studies have shown that MS is associated with high tumor necrosis factor (TNF‐α) levels. In fact, TNF‐α has been proposed to be a useful marker for clinical diagnosis of inflammation at an early stage. Therefore, we analyzed TNF‐α concentrations in Mexican individuals with or without MS and related these levels to the associated MS components. Clinical, anthropometric, and biochemical data were analyzed in 41 healthy and 39 MS individuals. Individuals were similarly grouped by age and gender.The serum TNF‐α levels measured bya highly sensitive enzyme‐linked immunosorbent assay (ELISA) kit were increased significantly in MS subjects compared with healthy individuals (P<0.001). The assay showed 78.1% sensitivity and 61.5% specificity with a cut‐point level of 1.36 pg/mL. TNF‐α levels higher than the cut‐point value were correlated with insulin resistance indices. These findings support the hypothesis that serum TNF‐α concentration could be a useful marker for early MS diagnosis. Nevertheless, we suggest the establishment of specific cut‐point values in each studied population to evaluate potential clinical applications. J. Clin. Lab. Anal. 23:51–56, 2009. © 2009 Wiley‐Liss, Inc.     

Pulmonary prostacyclin synthase overexpression in transgenic mice protects against development of hypoxic pulmonary hypertension

Prostacyclin synthase (PGIS) is the final committed enzyme in the metabolic pathway leading to prostacyclin (PGI2) production. Patients with severe pulmonary hypertension have a PGIS deficiency of their precapillary vessels, but the importance of this deficiency for lung vascular remodeling remains unclear. We hypothesized that selective pulmonary overexpression of PGIS may prevent the development of pulmonary hypertension. To study this hypothesis, transgenic mice were created with selective pulmonary PGIS overexpression using a construct of the 3.7-kb human surfactant protein-C (SP-C) promoter and the rat PGIS cDNA. Transgenic mice (Tg+) and nontransgenic littermates (Tg-) were subjected to a simulated altitude of 17,000 ft for 5 weeks, and right ventricular systolic pressure (RVSP) was measured. Histology was performed on the lungs. The Tg+ mice produced 2-fold more pulmonary 6-keto prostaglandin F1alpha (PGF1alpha) levels than did Tg- mice. After exposure to chronic hypobaric hypoxia, Tg+ mice have lower RVSP than do Tg- mice. Histologic examination of the lungs revealed nearly normal arteriolar vessels in the Tg+ mice in comparison with vessel wall hypertrophy in the Tg- mice. These studies demonstrate that Tg+ mice were protected from the development of pulmonary hypertension after exposure to chronic hypobaric hypoxia. We conclude that PGIS plays a major role in modifying the pulmonary vascular response to chronic hypoxia. This has important implications for the pathogenesis and treatment of severe pulmonary hypertension.     

Sumatriptan reduces severity of status epilepticus induced by lithium–pilocarpine through nitrergic transmission and 5‐HT1B/D receptors in rats: A pharmacological‐based evidence

Status epilepticus (SE) is a life‐threatening neurologic disorder that can be as both cause and consequence of neuroinflammation. In addition to previous reports on anti‐inflammatory property of the anti‐migraine medication sumatriptan, we have recently shown its anticonvulsive effects on pentylenetetrazole‐induced seizure in mice. In the present study, we investigated further (i) the effects of sumatriptan in the lithium–pilocarpine SE model in rats, and (ii) the possible involvement of nitric oxide (NO), 5‐hydroxytryptamin 1B/1D (5‐HT_1B/1D) receptor, and inflammatory pathways in such effects of sumatriptan. Status epilepticus was induced by lithium chloride (127 mg/kg, i.p) and pilocarpine (60 mg/kg, i.p.) in Wistar rats. While SE induction increased SE scores and mortality rate, sumatriptan (0.001‐1 mg/kg, i.p.) improved it (P < 0.001). Administration of the selective 5‐HT_1B/1D antagonist GR‐127935 (0.01 mg/kg, i.p.) reversed the anticonvulsive effects of sumatriptan (0.01 mg/kg, i.p.). Although both tumor necrosis factor‐α (TNF‐α) and NO levels were markedly elevated in the rats' brain tissues post‐SE induction, pre‐treatment with sumatriptan significantly reduced both TNF‐α (P < 0.05) and NO (P < 0.001) levels. Combined GR‐127935 and sumatriptan treatment inhibited these anti‐inflammatory effects of sumatriptan, whereas combined non‐specific NOS (L‐NAME) or selective neuronal NOS (7‐nitroindazole) inhibitors and sumatriptan further reduced NO levels. In conclusion, sumatriptan exerted a protective effect against the clinical manifestations and mortality rate of SE in rats which is possibly through targeting 5‐HT_1B/1D receptors, neuroinflammation, and nitrergic transmission.     

不同低氧方式对大鼠肺组织氧化应激状态及肺小动脉重构的影响

目的 通过研究不同低氧方式(持续低氧与慢性间歇低氧)对大鼠肺组织氧化应激状态及肺动脉重构的影响,以探讨低氧性肺动脉高压的发生机制.方法 18只SD雄性大鼠按随机数字表法分为持续低氧(CH)、慢性间歇低氧(CIH)和对照组(UC)共3组,每组6只.CIH组大鼠循环给予氮气和压缩空气(每循环180 s,舱内最低氧浓度达6%~8%,维持20~25 s,然后恢复至21%,7 h/d),CH组持续给予氮气(舱内氧浓度保持10%~12%,7 h/d),对照组大鼠常规饲养.结果 实验第6周CH组分别与CIH组、对照组比较:肺组织丙二醛、抑制羟自由基能力及氧化低密度脂蛋白水平差异有统计学意义(P<0.05或P<0.001).CH组肺小动脉管壁厚度、WT%、WA%分别与其他两组比较均有明显增高(P<0.05或P<0.001).肺小动脉管壁厚度、WT%、WA%分别与肺组织丙二醛、氧化低密度脂蛋白水平呈正相关(P<0.05);与抑制羟自由基能力水平呈负相关(P<0.05).结论 不同低氧方式对大鼠肺组织局部氧化应激及肺小动脉重构的影响存在差异,CH对大鼠肺小动脉重构的影响比CIH更显著,其原因可能与持续低氧引起肺组织局部强烈的氧化应激有关,这可能是低氧性肺动脉高压的重要机制之一.     

Phytol,a diterpene alcohol,inhibits the inflammatory response by reducing cytokine production and oxidative stress

Studies have shown that diterpenes have anti‐inflammatory and redox‐protective pharmacological activities. The present study aimed to investigate the anti‐inflammatory properties of phytol, a diterpene alcohol, in a mouse model of acute inflammation, and phytol effect on leukocyte recruitment, cytokines levels, and oxidative stress. The anti‐inflammatory activities of phytol were assessed by measuring paw edema induced by different inflammatory agents (e.g., λ‐carrageenan, compound 48/80, histamine, serotonin, bradykinin, and prostaglandin E₂ [PGE₂]), myeloperoxidase (MPO) activity, peritonitis model and cytokine levels. Further, oxidative stress was evaluated by determining glutathione (GSH) levels and malondialdehyde (MDA) concentration. The results showed that phytol (7.5, 25, 50, and 75 mg/kg) significantly reduced carrageenan‐induced paw edema, in a dose‐dependent manner. In addition, phytol (75 mg/kg) inhibited compound 48/80‐, histamine‐, serotonin‐, bradykinin‐ and PGE₂‐induced paw edema. It also inhibited the recruitment of total leukocytes and neutrophils; decreased MPO activity, tumor necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β) levels, and MDA concentration; and increased GSH levels during carrageenan‐induced acute inflammation. These results suggest that phytol attenuates the inflammatory response by inhibiting neutrophil migration that is partly caused by reduction in IL‐1β and TNF‐α levels and oxidative stress.     

Pulmonary vascular resistance and proper timing of percutaneous balloon mitral valvotomy

It is frequent to see pulmonary hypertension (PH) in patients with mitral stenosis (MS) secondary to increased pulmonary vascular resistance (PVR), data about the effect of PVR on the results of percutaneous balloon mitral valvotomy (PBMV) are insufficient. To detect the role of PVR in predicting residual PH immediately after PBMV. This prospective study comprised 49 consecutive patients with moderate to severe MS who were investigated pre and within 48 h post a successful PBMV for the first time. Echocardiography was used to assess the mitral valve area (MVA), mean transmitral pressure gradient (MPG), mitral valve resistance (MVR), right ventricular systolic pressure (RVSP) and PVR. Patients were classified into two groups according to the pre PVR (≥?1.6 WU as group I and < 1.6 as group II). At baseline compared to group II (32 patients), Group I (17 patients) had higher MPG (13.6?±?5.2 vs. 11.7?±?3.7 mmHg, P?<?0.05), RVSP (45.6 vs. 37.9 mmHg, P?<?0.001) and PVR (2.2?±?0.1 vs. 1.2?±?0.1WU, P?<?0.001) with no significant difference regarding age, gender, MVS, MVA and MVR. Patients of group I had comparatively lower improvement immediate post procedural of RVSP and PVR with no significant difference in immediate post procedural improvement in NYHA classification, MVA, MPG and MVR. Basal PVR?>?1.8WU was proved to be a highly specific (91%), a good predictor (AUC 0.78) of persistent elevation of RVSP?>?50 mmHg post PMV. Pathological rise of PVR that associates MS had provided a strong and an independent predictor of persistent pulmonary hypertension post PBMV and by this aspect it could be used as a valuable tool as MVA and MPG to send patients earlier for PBMV even with less severe MS. PVR?>?1.81 WU could be used as a noninvasive parameter for predicting regression of PH immediately after PBMV.     

Visfatin expression in subcutaneous adipose tissue of pre-menopausal women: relation to hormones and weight reduction

Background A novel adipokine, visfatin, was found to be related to adiposity in humans and regulated by a number of hormonal signals. The aim of this study was to investigate the relationships of visfatin expression in adipose tissue with potential regulatory factors such as insulin, testosterone and tumor necrosis factor‐α (TNF‐α) and to elucidate the effect of a diet induced weight reduction on adipose tissue mRNA expression and plasma levels of visfatin. Materials and methods Biopsies of subcutaneous abdominal adipose tissue (SCAAT) and plasma samples were obtained at the beginning of the study from 47 pre‐menopausal women (age 38·7 ± 1·7 years, body mass index (BMI) 27·9 ± 1·4 kg m^?2), consisting of 15 lean, 16 overweight and 16 obese subjects. The subgroup of 32 overweight/obese women (age 42·1 ± 1·9 years, BMI 31·2 ± 0·9 kg m^?2) underwent a 12 week hypocaloric weight reducing diet and samples were obtained at the end of the diet. Biopsy samples were analysed for visfatin and TNF‐α mRNA levels and plasma was analysed for relevant metabolites and hormones. Results In the group of 47 subjects visfatin mRNA expression in SCAAT was negatively correlated with plasma free testosterone (r = –0. 363, P < 0·05) and BMI (r = –0·558, P < 0·01) and positively associated with adipose tissue TNF‐α mRNA expression (r = 0·688, P < 0·01). The diet resulted in the reduction of body weight and in the decrease of plasma insulin, free testosterone and TNF‐α levels. In the group of overweight/obese subjects visfatin mRNA in SCAAT increased after the diet and the diet induced increase was positively correlated with the magnitude of body weight loss. Conclusion Visfatin mRNA expression in SCAAT is associated with TNF‐α expression, plasma free testosterone and BMI in pre‐menopausal women. A weight reducing hypocaloric diet results in the increase of visfatin mRNA in SCAAT.     

Prolidase activity dysregulation and its correlation with oxidative-antioxidative status in chronic obstructive pulmonary disease

Background: Chronic obstructive pulmonary disease (COPD) is a consequence of an underlying chronic inflammatory disorder of the airways that is usually progressive and causes dysregulation in the metabolism of collagen. Prolidase has an important role in the recycling of proline for collagen synthesis and cell growth. Objective: We measured and compared prolidase activity in healthy individuals with COPD patients to find out that whether its activity might reflect disturbances of collagen metabolism in the patients. We also investigated oxidative–antioxidative status and its relationship with prolidase activity in this disease. Methods: Thirty voluntary patients with COPD and 30 healthy control subjects with similar age range and sex were included into the study. Plasma prolidase activities, total antioxidant capacity (TAC) and lipid peroxidation (LPO) levels were measured in the patient and control groups. Results: Plasma prolidase activity and TAC levels were significantly lower, and LPO levels were significantly higher in the patients than those in the control subjects (P<0.05, P<0.001, and P<0.001, respectively). Significant correlations were detected between plasma prolidase activity and TAC and LPO levels in the patients group (r=0.679, P<0.001; r=?426, P<0.05, respectively). Conclusions: The results suggest that oxidative–antioxidative balance and collagen turnover are altered by the development of COPD in human lungs, and prolidase activity may reflect disturbances of collagen metabolism in this pulmonary disease. Monitoring of plasma prolidase activity and oxidative–antioxidative balance may be useful in evaluating fibrotic processes and oxidative damage in the chronic inflammatory lung disease in human. J. Clin. Lab. Anal. 25:8–13, 2011. © 2011 Wiley‐Liss, Inc.     

Effect of alpha‐lipoic acid on endometrial implants in an experimental rat model

To investigate the antioxidant and anti‐inflammatory effects of alpha‐lipoic acid (ALA) in the treatment of endometriosis in an experimental rat model by evaluating biochemical and histopathologic parameters. Experimental endometriosis was induced by the peritoneal implantation of autologous endometrial tissue. The rats were randomly divided into two groups with eight rats each. Group I was intraperitoneally administered ALA 100 mg/kg/day for 14 days. Group II was intraperitoneally administered saline solution at the same dosage and over the same period. Endometrial implant volume was measured in both groups both pre‐ and post‐treatment. Tumor necrosis factor alpha (TNF‐α) was measured in peritoneal fluid. Total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) were assessed in serum. The implants were histopathologically evaluated. In the ALA group, the serum TOS and OSI levels, the endometrial implant volumes, the TNF‐α levels in serum and peritoneal fluid, and the histopathologic scores were significantly lower compared to the control group (P < 0.05). Alpha‐lipoic acid may have a therapeutic potential in the treatment of endometriosis due to its antioxidant and anti‐inflammatory effects.     

Relationship between tumor necrosis factor‐alpha and ammonia in patients with hepatic encephalopathy due to chronic liver failure

BACKGROUND. We have recently demonstrated that in humans, circulating levels of tumor necrosis factor‐α (TNF) correlate positively with severity of hepatic encephalopathy (HE) due to chronic liver failure.

AIM. The main aim of this larger population study is to determine the relationship between TNF and ammonia in patients with HE and chronic liver failure due to liver cirrhosis.

METHODS. Circulating levels of TNF and ammonia were measured in 108 patients with liver cirrhosis due to various etiologies in various clinical grades of HE (grades 0–4). TNF concentrations were measured in venous serum using commercially available solid‐phase high sensitivity enzyme‐linked immunosorbent assay. Ammonia levels were determined in venous plasma by the enzymatic method, using the glutamate dehydrogenase reaction.

RESULTS. The mean±SEM values of circulating levels of TNF and ammonia at presentation in patients with grade 0 of HE (n = 30) were 3.89±0.2?pg/mL and 49.8±2.8?µg/mL respectively, in patients with grade 1 of HE (n = 26) were 8.56±0.34?pg/mL and 101.6±6.5?µg/mL respectively, in patients with grade 2 of HE (n = 22) were 11.59±0.48?pg/mL and 160.3±10.7?µg/mL respectively, in patients with grade 3 of HE (n = 20) were 19.98±0.94?pg/mL and 228.8±16.1?µg/mL respectively, and in patients with grade 4 of HE (n = 10) were 51.53±8.59?pg/mL and 284.2±20.3?µg/mL respectively. A significant positive correlation was found between circulating levels of TNF and those of ammonia (r = 0.62, P<0.0001), and also between circulating levels of both substances and severity of HE in these patients (r = 0.95, P<0.0001, and r = 0.9, P<0.0001 respectively). TNF and ammonia were both significant independent predictors of severity of HE (P<0.0001 for both variables).

CONCLUSION. The results of this study demonstrate a significant relationship between TNF and ammonia in patients with chronic liver failure and HE, and so strengthen the suggestion that TNF could be strongly involved in the pathogenesis of HE in these patients. Hence, we suggest a new theory in the pathogenesis of HE, the ‘TNF theory’.     

上腔静脉频谱在评价常压低氧致大鼠肺高压中的应用

目的 探讨上腔静脉（SVC）频谱在评价常压低氧所致大鼠肺高压（PH）中的应用价值。方法 将18只健康成年雄性SD大鼠随机分为PH组（n=12）和对照组（n=6）,PH组采用常压低氧法建立动物模型。对两组大鼠进行超声检查,测量肺动脉内径（PAD）和肺动脉峰值流速（PAV_max）、三尖瓣E峰峰值流速（TVE_max）、S波流速（S）、D波流速（D）、AR波流速（AR）,并计算AR/S和AR/D;采用右心导管测量右心房压力（RAP）、右心室收缩压（RVSP）,肺动脉收缩压（PASP）、肺动脉平均压（PAMP）;取血测量血清NO含量。处死大鼠后取心脏测量右心室肥厚指数,取肺组织进行病理学检查。结果 与对照组比较,PH组RAP、RVSP、PASP、PAMP增高,S波、D波速度减低,AR/D及AR/S升高,差异均有统计学意义（P均<0.05）。RVSP与AR/S、AR/D呈中等和极强相关（r=0.494,P<0.05;r=0.830,P<0.001）,PAMP与AR/D呈强相关（r=0.725,P<0.01）,与AR/S无相关性（r=0.517,P=0.07）。PH组大鼠肺小动脉出现不同程度内中膜增厚,管腔变小,平滑肌增生。两组右心室肥厚指数、体质量及NO含量差异无统计学意义（P均>0.05）。结论 PH时SVC频谱表现为S波、D波降低,AR/S、AR/D增大,且与肺动脉压力密切相关,可作为多普勒超声评价PH的指标。     

Correlation of seizures and biochemical parameters of oxidative stress in experimentally induced inflammatory rat models

The role of oxidative stress in the pathogenesis of various conditions including epilepsy, inflammatory bowel disease and rheumatoid arthritis is evolving. The aim of this study was to find out the correlation between various inflammatory models with seizures and antioxidant parameters. Fifty‐four male rats were divided into three groups of colitis, adjuvant arthritis and cotton wool granuloma (CWG). Each group had three subgroups of control, model and treatment. Thalidomide was used as treatment in colitis and arthritis group, whereas etoricoxib was used in CWG group. In colitis and arthritis groups, thalidomide was administered for 3 and 17 days, respectively, whereas etoricoxib was administered for 7 days in CWG group. At the end of treatment protocols, a subconvulsive dose of pentylenetetrazole (PTZ) (40 mg/kg i.p.) was injected intraperitoneally to note seizure onset and score. After confirming the presence of inflammation by morphological and histological studies, plasma and brain biochemical parameters of oxidative stress were estimated. The models of colitis, arthritis and CWG were effectively produced as evidenced by morphological scores (P < 0.001). Thalidomide reduced the morphological score (P < 0.002) and seizure grade (P < 0.001), whereas increased seizure onset (P < 0.001) in the arthritis group. There was an increase in malondialdehyde levels in the brain of thalidomide‐treated groups (P < 0.002) and a significant decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels. There was neither improvement in seizure nor any significant changes in lipid peroxidation and antioxidant enzyme levels in etoricoxib‐treated group. Thalidomide was effective in reducing the extent of arthritis as well as reducing the seizure scoring and increasing seizure onset in the adjuvant arthritis group. As it increased lipid peroxidation and reduced SOD and GPx, further evaluation is necessary with respect to oxidative stress.     

Possible involvements of glutamate and adrenergic receptors on acute toxicity of methylphenidate in isolated hippocampus and cerebral cortex of adult rats

Neurodegeneration induced by methylphenidate (MPH), as a central stimulant with unknown long‐term consequences, in adult rats’ brain and the possible mechanisms involved were studied. Rats were acutely treated with MPH in the presence and absence of some receptor antagonists such as ketamine, topiramate, yohimbine, and haloperidol. Motor activity and anxiety level in rats were monitored. Antioxidant and inflammatory parameters were also measured in isolated hippocampus and cerebral cortex. MPH‐treated groups (10 and 20 mg/kg) demonstrated anxiety‐like behavior and increased motor activity. MPH significantly increased lipid peroxidation, GSSG content, IL‐1β and TNF‐α levels in isolated tissues, and also significantly reduced GSH content, superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR) activities in hippocampus and cerebral cortex. Pretreatment of animals by receptor antagonists caused inhibition of MPH‐induced motor activity disturbances and anxiety‐like behavior. Pretreatment of animals by ketamine, topiramate, and yohimbine inhibited the MPH‐induced oxidative stress and inflammation; it significantly decreased lipid peroxidation, GSSG level, IL‐1β and TNF‐α levels and increased GSH content, SOD, GPx, and GR activities in hippocampus and cerebral cortex of acutely MPH‐treated rats. Pretreatment with haloperidol did not cause any change in MPH‐induced oxidative stress and inflammation. In conclusion, acute administration of high doses of MPH can cause oxidative and inflammatory changes in brain cells and induce neurodegeneration in hippocampus and cerebral cortex of adult rats and these changes might probably be mediated by glutamate (NMDA or AMPA) and/or α₂‐adrenergic receptors.     

Inhibition of transient receptor potential vanilloid‐1 confers neuroprotection,reduces tumor necrosis factor‐alpha,and increases IL‐10 in a rat stroke model

Stroke is a major cause of mortality and long‐term disability in adults. Transient receptor potential vanilloid‐1 (TRPV1) plays a crucial role in neuroinflammation. In this study, the effects of TRPV1 agonist (capsaicin) and antagonist (AMG9810) on cerebral ischemia were investigated. Forty male Wistar rats were assigned to the following experimental groups: sham, vehicle) ischemic), AMG9810 (selective TRPV1 antagonist, 0.5 mg/kg; 3 h after stroke), and capsaicin (1 mg/kg; 3 h after stroke). Stroke was induced by permanent middle cerebral artery occlusion and neurological deficits were evaluated 1, 3, and 7 days after stroke. Then, infarct volume, brain edema, body temperature, mRNA expression of TRPV1, and serum concentrations of tumor necrosis factor‐alpha (TNF‐α) and IL‐10 were measured. Compared to the vehicle group, AMG9810 significantly decreased the infarct volume (P < 0.01). Latency for the removal of sticky labels from the forepaw and the hanging time were significantly decreased and increased, respectively, following administration of AMG9810 (P < 0.01 and P < 0.001 vs. vehicle) 3 and 7 days after stroke. Compared to the sham group, the mRNA expression of TRPV1 was significantly increased in vehicle group (P < 0.01). Administration of AMG9810 significantly increased the anti‐inflammatory cytokine IL‐10 and decreased the inflammatory cytokine TNF‐α (P < 0.05). Moreover, our results indicate that AMG9810 might a promising candidate for the hypothermic treatment of stroke. The findings also suggest a key role for AMG9810 in reducing inflammation after stroke and imply that TRPV1 could be a potential target for the treatment of ischemic stroke.     

Deletion of the inducible nitric oxide synthase gene reduces peripheral morphine tolerance in a mouse model of chronic inflammation

The implication of inducible nitric‐oxide synthase (iNOS) on peripheral tolerance to morphine was evaluated in wild‐type (WT) and iNOS knockout mice. Chronic inflammation was induced by subplantar (s.p.) injection of Complete Freund’s Adjuvant (CFA), and morphine tolerance by subcutaneous implantation of a 75 mg morphine‐pellet. Withdrawal was assessed after the intraperitoneal injection of 2 mg/kg naloxone. Antinociception was assessed (Randall‐Selitto test) 5 min after a fixed dose of s.p. morphine (16 μg). In the absence of inflammation, s.p. morphine did not induce antinociception, while during CFA‐inflammation produced 47.4 ± 0.8 and 38.8 ± 2.7% inhibitions respectively, in each genotype (P < 0.05). In morphine‐tolerant mice with CFA‐inflammation, no antinociception could be elicited in WT mice (2.4 ± 0.3% inhibition); however, iNOS knockout mice showed significant antinociception (33.1 ± 0.9%) (P < 0.001). Thus, iNOS gene deletion partially prevented tolerance to the peripheral effects of morphine, and significantly attenuated withdrawal‐induced hyperactivity.     

Prothrombotic effects of diclofenac on arteriolar platelet activation and thrombosis in vivo

Summary. Background: Diclofenac, like selective cyclooxygenase‐2 inhibitors, which alter vascular levels of platelet active prostaglandins, has been reported to increase rates of acute myocardial infarction. Objective: The study was performed to investigate, in an animal model of arterial thrombosis in vivo, whether diclofenac differentially influences platelet activation and thrombosis in vessels under non‐stimulated conditions or during acute systemic inflammation, such as induced by tumor necrosis factor‐α (TNF‐α). Methods: Platelet–vessel wall interaction (PVWI), firm platelet adhesion and arterial thrombosis following vessel injury were analyzed by intravital microscopy in arterioles of hamsters in the dorsal skinfold chamber model. Prostacyclin [prostaglandin I₂ (PGI₂)] and thromboxane A₂ (TxA₂) metabolites were measured. In vitro, endothelial adhesion molecule expression in cultured human microvascular endothelial cells was analyzed. Results: Under non‐stimulated conditions, diclofenac (1 mg kg^?1) enhanced PVWI, which was not mediated by increased adhesion molecule expression, but by decreased systemic PGI₂ levels. Following ferric chloride‐induced endothelial injury, diclofenac accelerated thrombotic vessel occlusion time, an effect that was reversed by the stable PGI₂ analog iloprost. TNF‐α, through induction of endothelial adhesion molecule expression, also enhanced PVWI, firm adhesion, and arterial thrombosis, but simultaneous treatment with TNF‐α and diclofenac did not have an additive effect. Conclusions: By decreasing levels of PGI₂ without, at the same time, altering prothrombotic TxA₂ levels, diclofenac can exert prothrombotic effects. However, this is not the case when an inflammatory situation is created by TNF‐α treatment. These data may explain the enhanced risk of acute myocardial infarction observed in patients taking diclofenac.     

The nitroxide tempol has similar antioxidant effects as physiological levels of 17β‐oestradiol in reversing ovariectomy‐induced oxidative stress in mice liver and kidney

Objective: Oestrogen defciency increases oxidative stress postmenopause, while tempol is an intracellular radical scavenger that interferes with the formation or effects of many radicals. We aimed to investigate the effects of oestrogen and tempol on oxidative stress parameters in the kidney and liver of ovariectomized mice. Material and methods: Forty 8‐week‐old female Bald/c mice were divided into five groups: sham‐operated, ovariectomized mice without treatment, ovariectomized mice treated with tempol, ovariectomized mice treated with 17β‐oestradiol and ovariectomized mice treated with 17β‐oestradiol and tempol. Oxidative stress in liver and kidney tissues was investigated by measuring 2‐thiobarbituric acid reactive substances (TBA‐RS), reduced glutathione, myeloperoxidase, superoxide dismutase and catalase levels. Results: TBA‐RS levels were increased and reduced glutathione, myeloperoxidase, superoxide dismutase levels were decreased in the tissues of ovariectomized mice. This effect of ovariectomy on oxidative stress parameters was opposed significantly by the administration of tempol and 17β‐oestradiol either alone or in combination. Ovariectomy reduced the kidney catalase levels, but the effect was not statistically significant (p>0.05). On the other hand, catalase levels were elevated significantly in all treatment groups compared to those of the ovariectomized group (p<0.05). Conclusion: These study findings demonstrate that tempol significantly opposes the oxidative stress generated by ovariectomy. This effect, which is evident in remote tissues such as liver and kidney, is comparable to that of physiological levels of oestradiol.     

Capillary filtration coefficient and urinary albumin leak at altitude

Rapid ascent to altitude risks the development of acute mountain sickness. This study demonstrates changes in peripheral capillary filtration coefficient and renal protein loss in subjects suffering from various degrees of mountain sickness after passive ascent to 4559 m. Capillary filtration coefficient of the calf capillary bed, measured by computer-based multistep strain gauge plethysmography, increased significantly after 23.5 h at altitude when symptoms were most severe: 4.45 (2.76–6.03) to 6.31 (3.86–11.07) ml min^–1 per 100 g of tissue mmHg^–1, median (range) (P <0.02). Urinary albumin excretion was increased after one night at altitude from 1.1 (0.6–1.5) to 2.45 (1.0–6.8) mg of albumin per mmol of creatinine (P <0.05). These results demonstrate simultaneous leakage of a peripheral capillary bed to fluid measured by strain gauge plethysmography, and renal albumin leak, and suggest a systemic process of increased capillary leakage for different-sized molecules caused by rapid exposure to hypobaric hypoxia.     

The Proinflammatory Cytokine Response following Resuscitation in the Swine Model Depends on the Method of Ventricular Fibrillation Induction

Objectives: A systemic inflammatory response has been reported following resuscitation from cardiac arrest. The purpose of this study was to compare the magnitude of the tumor necrosis factor‐α (TNF‐α) response in two different swine models of ventricular fibrillation (VF) arrest. Methods: This was a randomized comparative trial conducted with domestic swine (N = 28, mean weight 40 kg, range 34–49 kg) of both genders. Anesthetized and instrumented swine were randomized to electrically induced VF (n = 14) or spontaneous VF induced by occlusion of a coronary artery (n = 14). After 8 minutes of VF, countershocks were given and standard advanced cardiac life support was initiated. Resuscitated animals were observed for 3 hours, and hemodynamics, base excess, and TNF‐α concentrations were measured at intervals. Results: TNF‐α concentrations were significantly greater in the ischemic VF group throughout the postresuscitation period. Multivariate modeling demonstrated that the TNF‐α level was dependent on the method of VF induction and correlated with ischemia time (untreated VF period plus time to restoration of circulation) and the degree of postresuscitation hypoperfusion as reflected in base excess measurements. Conclusions: This study demonstrates that TNF‐α concentrations increase after resuscitation from cardiac arrest and that the TNF‐α response is more profound in animals subjected to ischemic, spontaneous VF. The observed differences may be due to a longer resuscitation time and persistent postresuscitation hypoperfusion in the ischemic VF group. These differences need to be considered in studies evaluating mechanisms of postresuscitation organ dysfunction and defining mortality markers.     

Inhalation of LPS induces inflammatory airway responses mimicking characteristics of chronic obstructive pulmonary disease

Aim: Inhalation of lipopolysaccharide (LPS) produces both systemic and pulmonary inflammatory responses. The aim of this study was to further characterize the response to LPS in order to develop a human model suitable for early testing of drug candidates developed for the treatment for chronic obstructive pulmonary disease (COPD). Materials: Blood and induced sputum were obtained 4, 24 and 48 h following inhalation of saline and LPS (5 and 50 μg). Blood was analysed for C‐reactive protein (CRP), α₁‐antitrypsin and neutrophils/leucocytes, and sputum was analysed for biomarkers of neutrophil inflammation and remodelling activities, i.e. neutrophil elastase (NE) protein/activity and α₁‐antitrypsin. Levels of tumour necrosis factor‐α (TNFα) were measured in both blood and sputum. Urine was collected 0–24 and 24–48 h postchallenge, and desmosine, a biomarker of elastin degradation, was measured. Results: Lipopolysaccharide inhalation induced dose‐dependent flu‐like symptoms and increases in plasma CRP and α₁‐antitrypsin as well as increases in blood neutrophil/leucocyte numbers. Furthermore, LPS produced increases in sputum TNFα and sputum NE activity. Urine levels of desmosine were unaffected by the LPS challenge. All subjects recovered 48 h postchallenge, and indices of inflammatory activity were significantly lower at this observation point cf 24 h postchallenge. Conclusion: Inhalation of LPS in healthy volunteers can be used as a safe and stable model of neutrophil inflammation. Blood/plasma and sputum indices can be employed to monitor the response to LPS. We suggest that this model may be used for initial human studies of novel COPD‐active drugs.