[Quality Control Indexes for Oncology (2023 edition) and hot topics in breast surgery]

The National Health Commission of the People's Republic of China has formulated the Quality Control Indexes for Oncology (2023 edition), with the objective of improving medical quality scientifically, refined and standardized. Among these indexes, the rate of pretreatment clinical TNM staging and the coincidence rate of evaluation of pretreatment TNM staging lay national standards for patients to formulate rational and targeted treatment strategies. This article reviewed the literature and referred to Chinese Medical Association Clinical Practice Guide for Breast Surgery, and presented recommendations for the hot topics of breast surgery, such as pathological sampling of the breast specimen, sentinel lymph node biopsy for early-stage breast cancer, breast conserving surgery, axillary lymph node dissection, breast reconstruction surgery, endoscopic-assisted breast surgery, the principles of surgical treatment for metastatic breast cancer, neoadjuvant treatment for advanced disease, and surgical grade of breast surgery, which have been widely concerned in recent years, to help improve homogenization of breast cancer treatment in China.

[Association of greenness, nitrogen dioxide with the prevalence of hypertension among the elderly over 65 years old in China]

Objective: To investigate the association of mixed exposure to greenness and nitrogen dioxide(NO₂) and hypertension among the older adults aged 65 years and over in China. Methods: The study subjects were from the Chinese Longitudinal Healthy Longevity Survey from 2017 to 2018. A total of 15 423 older adults aged 65 years and over meeting the criteria were finally included in the study. A questionnaire survey was used to collect information on demographic characteristics, lifestyle habits and self-reported prevalence of hypertension. Blood pressure values were obtained through physical examination. The level of normalized difference vegetation index(NDVI) was measured by the Medium-resolution Imaging Spectral Radiator(MODIS) of the National Aeronautics and Space Administration(NASA). The concentration of NO₂ was from China's surface air pollutant data set. Meteorological data was from NASA MERRA-2. The exposure to NDVI and NO₂ for each study subject was calculated based on the area within a 1 km radius around their residence. The association between mixed exposure of NDVI and NO₂ as well as their interaction and hypertension in older adults was analyzed by using the multivariate logistic regression model. The restrictive cubic spline(RCS) function was used to explore the exposure-response relationship between greenness and NO₂ and the risk of hypertension in study subjects. Results: The mean age of 15 423 older adults were (85.6±11.6). Women accounted for 56.3%(8 685/15 423) and 55.6%(8 578/15 423) lived in urban areas. The mean time of residence was (60.9±28.5) years. 59.8% of participants were with hypertension. The mean NDVI level was 0.41±0.13, and the mean NO₂ concentration was (32.18±10.36) μg/cm³. The results of multivariate logistic regression analysis showed that NDVI was inversely and linearly associated with the hypertension in older adults, with the OR(95%CI) value of 0.959(0.928-0.992). Compared with the T₁ group of NDVI, the risk of hypertension was lower in the T₃ group, with the OR(95%CI) value of 0.852(0.769-0.944), and the trend test was statistically significant(P<0.05). Compared with the T₁ group of NO₂, the risk of hypertension was higher in the T₂ and T₃ groups, with OR(95%CI) values of 1.160(1.055-1.275) and 1.244(1.111-1.393), and the trend test was statistically significant (P<0.05). The result of the RCS showed that NDVI was inversely and linearly associated with hypertension in older adults. NO₂ was nonlinearly associated with hypertension in older adults. The interaction analysis showed that NDVI and NO₂ had a negative multiplicative interaction on the risk of hypertension, with OR(95%CI) value of 0.995(0.992-0.997). Conclusion: Exposure to greenness and NO₂ are associated with hypertension in older adults.

Association of insulin resistance with bone mineral density in a nationwide health check-up population in China

INTRODUCTION

Insulin resistance (IR) is closely associated with cardio-metabolic diseases. However, the impact of IR on bone mass remains obscure. The present study is to evaluate the association between the triglyceride-glucose (TyG) indicated IR and bone mass in a nationwide health check-up population in China.

METHODS

We conducted a retrospective cross-sectional study including 788,247 participants and a longitudinal cohort study in 8770 participants who had repeated measurements of TyG index and bone mass in at least a 2-year follow-up period. The restricted cubic splines and logistic models were used to analyze the association between IR and bone mass in the cross-sectional study. The Cox model was applied to evaluate the relationship between baseline IR and the subsequent incidence of low bone mass and osteoporosis in the longitudinal study.

RESULTS

In the cross-sectional study, the TyG index had positive correlations with low bone mass, osteoporosis, or both after adjusting for confounding factors (all P < 0.001). In the longitudinal cohort study, the baseline TyG index was significantly associated with the incidence of low bone mass, osteoporosis, or both during the follow-up period, with hazard ratios (HRs) of 1.56 (95 % confidence interval [CI]: 1.25, 1.93, P < 0.05), 1.66 (95%CI: 1.06, 2.59, P < 0.05), and 1.55 (95%CI: 1.27, 1.88, P < 0.05) after adjusting for confounding factors, respectively.

CONCLUSIONS

These results suggest that IR indicated by TyG is significantly associated with an increased risk of low bone mass and osteoporosis. Therefore, bone mass monitoring and early prevention strategies may be needed in individuals with IR to prevent the occurrence of low bone mass and osteoporosis.

[Association of greenness exposure with waist circumference and central obesity in Chinese adults aged 65 years and over]

Objective: To examine the association of greenness exposure with waist circumference (WC) and central obesity in older adults in China. Methods: Based on the cross-sectional data from the Chinese Longitudinal Healthy Longevity Survey in 2017-2018, 14 056 participants aged 65 years and over were included. Demographic characteristics, lifestyle, WC, and other information were collected through a questionnaire and physical examination. Based on the satellite monitoring data of moderate-resolution imaging spectroradiometer (MODIS) provided by NASA, the annual mean of normalized difference vegetation index (NDVI) within a radius of 1 000 meters was obtained as the measurement value of greenness exposure. Multivariate linear regression model, multivariate logistic regression model, and restricted cubic splines (RCS) model were used to analyze the association and dose-response relationship between greenness exposure and WC and central obesity in older adults in China. Results: A total of 14 056 participants were enrolled with a median age of 84.0 years [IQR: 75.0-94.0 years]. About 45.0% (6 330) of them were male and 48.6% (5 853) were illiterate. There were 10 964 (78.0%) participants from rural. The mean of WC was (84.4±10.8) cm. Central obesity accounted for 60.2% (8 465), and the NDVI range was (-0.06, 0.78). After adjusting for confounding factors, the multivariate linear regression model showed that the change value of WC in the urban group [β (95%CI):-0.49 (-0.93, -0.06)] was smaller than that in the rural [-0.78 (-0.98, -0.58)] for every 0.1 unit increase in NDVI (Pinteraction=0.022). Compared with the Q1 group in NDVI, WC of Q2 and Q3 groups in rural decreased, and the β (95%CI) values were-1.74 (-2.5, -0.98) and-2.78 (-3.55, -2.00), respectively. The multivariate logistic regression model showed that after adjusting for confounding factors, the risk of central obesity decreased for urban and rural older adults with an increase of 0.1 unit in NDVI, and the OR (95%CI) values were 0.87 (0.80, 0.95) and 0.86 (0.82, 0.89), respectively (Pinteraction=0.284). Compared with the Q1 group in NDVI, the risk of central obesity in the Q2 and Q3 groups in rural was lower, and the OR (95%CI) values were 0.68 (0.58, 0.80) and 0.57 (0.49, 0.68), respectively. The results of the multivariate regression model with RCS showed that there was a non-linear association of NDVI with WC (Pnonlinear=0.006) and central obesity (Pnonlinear=0.025). Conclusion: Greenness exposure is negatively associated with WC and central obesity in older adults in China.

Percutaneous Endoscopic Discectomy Via a Transforaminal Approach for L5/S1 Far-Lateral Disc Herniation Assisted by Intraoperative Computed Tomography

OBJECTIVE

To examine the clinical outcomes of a percutaneous lumbar transforaminal endoscopic discectomy (PTED) with intraoperative computed tomography (iCT) navigation for the treatment of L5-S1 far-lateral lumbar disc herniation (LDH).

METHODS

A total of 30 patients with L5-S1 far-lateral LDH who underwent PTED with iCT navigation from September 2016 to October 2020 were enrolled in this study. Outcomes were assessed using the visual analog scale pain score, the Oswestry Disability Index, the Japanese Orthopedic Association score, the EQ-5D-5 L and the modified Macnab criteria. Preoperative and postoperative complications were recorded.

RESULTS

The mean visual analog scale score for leg pain improved from 8.1 at baseline to 2.3, 0.9, 0.7 and 0.9 at 1 day, 1 week, 6 months, and 12 months postoperatively, respectively (P < 0.01). The mean Oswestry Disability Index improved from 78.1% at baseline to 45.5%, 21.9%, 12.6%, and 11.7% at 1 week, 1 month, 6 months, and 12 months postoperatively, respectively (P < 0.01); and the mean Japanese Orthopedic Association score improved from 8.6 at baseline to 14.2, 20.2, 24.4, and 25.6 at 1 day, 1 week, 6 months, and 12 months postoperatively, respectively (P < 0.01). At 12 months postoperatively, the EQ-5D-5 L value significantly increased, from -0.061 ± 0.138 to 0.903 ± 0.064. The rate of a good or excellent modified Macnab result was 93% (26/28) at 12 months postoperatively. In the present study, combined L5-S1 foraminal stenosis tended to lead poor outcomes, which required more postsurgical treatments.

CONCLUSIONS

With iCT navigation, PTED is a feasible and effective minimally invasive surgery for L5-S1 far-lateral LDH.

The global disease burden attributable to a diet low in fibre in 204 countries and territories from 1990 to 2019

OBJECTIVE

The relationship of a diet low in fibre with mortality has not been evaluated. This study aims to assess the burden of non-communicable chronic diseases (NCD) attributable to a diet low in fibre globally from 1990 to 2019.

DESIGN

All data were from the Global Burden of Disease (GBD) Study 2019, in which the mortality, disability-adjusted life-years (DALY) and years lived with disability (YLD) were estimated with Bayesian geospatial regression using data at global, regional and country level acquired from an extensively systematic review.

SETTING

All data sourced from the GBD Study 2019.

PARTICIPANTS

All age groups for both sexes.

RESULTS

The age-standardised mortality rates (ASMR) declined in most GBD regions; however, in Southern sub-Saharan Africa, the ASMR increased from 4·07 (95 % uncertainty interval (UI) (2·08, 6·34)) to 4·60 (95 % UI (2·59, 6·90)), and in Central sub-Saharan Africa, the ASMR increased from 7·46 (95 % UI (3·64, 11·90)) to 9·34 (95 % UI (4·69, 15·25)). Uptrends were observed in the age-standardised YLD rates attributable to a diet low in fibre in a number of GBD regions. The burden caused by diabetes mellitus increased in Central Asia, Southern sub-Saharan Africa and Eastern Europe.

CONCLUSIONS

The burdens of disease attributable to a diet low in fibre in Southern sub-Saharan Africa and Central sub-Saharan Africa and the age-standardised YLD rates in a number of GBD regions increased from 1990 to 2019. Therefore, greater efforts are needed to reduce the disease burden caused by a diet low in fibre.

[The Breast Cancer Cohort Study in Chinese Women: research design and preliminary results of clinical multi-center cohort]

Objective: The incidence of breast cancer in Chinese women continues to rise. The large breast cancer cohort studies in China are relatively scarce. There are many bottlenecks in the construction of large clinical cohort for breast cancer diagnosis, treatment, and prognoses, such as inconsistent standards, high rates of lost follow-up, repeated construction, and inability to share. To better solving the difficulties and problems faced by large-scale clinical cohort research in China, this project will cooperate with several tertiary A hospitals to establish a breast cancer cohort in Chinese women. It also provides a data platform and technical support for breast cancer multi-center clinical cohort research. Methods: Based on the evidence-based medicine and expert opinion and consensus, we established a breast cancer cohort standardized indicator set-recording baseline information, diagnosis and treatment-related information of the enrolled patients, and collecting biological specimens. According to the technical specification of long-term follow-up for the endpoint, data management, and data security and in the large population-based cohort study, a standardized follow-up system for the diagnosis, treatment, and prognosis of breast cancer prospective cohorts is formed. Results: Based on standardized data sets and the computer discipline's advantage from the University of Science and Technology Beijing, we integrate the new information technology methods, including dynamic information collection terminals and social networks. Thus, the quality of control programs on compliance and intelligence data was improved, and a Chinese women breast cancer cohort database was developed. By February 2020, 12 147 patients were included in the clinical cohort database. Biological specimens'resources in cohort construction were collected and cooperated with Shandong University to research the multi-center quality control system and shared evaluation system of biobanks. Building an open and shared biobank network and forming a full chain of breast cancer research platform. Conclusion: With the implementation of the "13(th) Five-Year Plan" precision medicine research, this study provides a research foundation for precision diagnosis and treatment of breast cancer and provides data support for the country to formulate relevant medical policies.

[Characteristics of peripheral blood leukocyte differential counts in patients with COVID-19]

To investigate the early changes of peripheral blood leukocyte differential counts in patients with COVID-19. Ten patients with COVID-19 and 30 patients with other viral pneumonia (non-COVID-19) admitted to Shanghai Jiao Tong University Affiliated Sixth People's Hospital and Jinshan Branch Hospital from January 22 to February 17, 2020 were enrolled in this study. The differential counts of white blood cells were analyzed. Patients in COVID-19 group showed relatively lower absolute white blood cell (WBC) count 4.95(3.90,6.03)×10(9)/L, lymphocyte absolute count 1.20(0.98,1.50)×10(9)/L and eosinophil absolute count 0.01(0.01,0.01)×10(9)/L. Leukopenia developed in two patients(2/10), lymphocytopenia also in two patients(2/10). Seven over ten patients presented with eosinophil cytopenia. In non-COVID-19 group, absolute WBC count was 8.20 (6.78,9.03) ×10(9)/L (P<0.001), lymphocyte absolute count 1.75(1.20,2.53)×10(9)/L(P=0.036), eosinophil absolute count 0.02(0.01,0.03)×10(9)/L(P=0.05). Lymphocytopenia occurred in (16.7%) patients, eosinophil cytopenia in 16.7% patients too. In conclusion, leukopenia, lymphocytopenia and eosinophil cytopenia are more common in COVID-19 patients than those in non- COVID-19 patients.

[Analysis of neoadjuvant docetaxel, carboplatin and trastuzumab (TCH) in HER-2-positive breast cancer]

Objective: To analyze docetaxel (T) and carboplatin (C) combined with trastuzumab (H) -TCH regimen as neoadjuvant systemic therapy in early breast cancer patients with human epidermal growth factor receptor 2 (HER-2) positive. Methods: From January 2008 to December 2014, the data of patients diagnosed as early breast cancer in Breast Disease Center of Peking University First Hospital were retrospective reviewed. The data of patients with HER-2 positive conducted TCH neoadjuvant therapy and surgery, and with the complete clinicopathological information were analyzed. Results: A total of 77 cases were enrolled in this study. We defined G2+ G3+ G4+ G5 as responsive group according to Miller-Payne grading system, the responsive rate was 84.4% (65/77). The rate of complete pathological remission (pCR) was 39.0% (30/77). The 5-year disease free survival (DFS) was 87.3%, and 5-year overall survival (OS) was 93.6%. There was a significant difference between DFS and OS in the responsive group and non-responsive group (DFS: χ²=6.762, P=0.009; OS: χ²=5.062, P=0.024). Conclusion: TCH is an effective neoadjuvant therapy for patients with HER-2 positive breast cancer, and the toxic and side effects were under control.

[Impact of carbon dioxide pneumoperitoneum in operating rooms on the health of medical staffs]

Objective: To evaluate the impact of CO(2) pneumoperitoneum in operating rooms on the health of medical staffs. Methods: In June 2016, the thirty-three medical staffs in operating rooms were chosen as the object of the research.Seventeen people who took part in the pneumoperitoneum operation were selected as a exposure group and sixteen people who took part in the laparotomy operation were selected as a control group.Vital signs and arterial blood gases of medical staffs in the two groups were both measured in pre-operation and post-operation. Occupational Health Questionnaires were conducted to collect information on age, weight and postoperative symptoms. The level of CO(2) in operating room was determined by a portable infrared CO(2) analyzer. Results: Compared with the control group, the concentration of CO(2) in the exposed group was higherat T(1), T(2) and T(3) (t=22.227, 13.583, 17.408, P<0.05) . Heart rates and PaCO(2) in the exposure group raised greatly (t=2.132, 2.129, P<0.05) , while pH decreased (t=-3.015, P<0.05) . The differences between the two groups were statistically significant. Conclusion: The increase of mild acidosis and thesense of job burnout in medical staffs could be caused by CO(2) pollution in the operating rooms.

Therapeutic potential of Panax ginseng and ginsenosides in the treatment of chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a major global health burden and will become the third largest cause of death in the world by 2030. It is currently believed that an exaggerated inflammatory response to inhaled irritants, in particular cigarette smoke, cause progressive airflow limitation. This inflammation, where macrophages, neutrophils and lymphocytes are prominent, leads to oxidative stress, emphysema, airways fibrosis and mucus hypersecretion. COPD responds poorly to current anti-inflammatory treatments including corticosteroids, which produce little or no benefit. Panax ginseng has a long history of use in Chinese medicine for respiratory conditions, including asthma and COPD.

OBJECTIVES

In this perspective we consider the therapeutic potential of Panax ginseng for the treatment of COPD.

RESULTS

Panax ginseng and its compounds, ginsenosides, have reported effects through multiple mechanisms but primarily have anti-inflammatory and anti-oxidative effects. Ginsenosides are functional ligands of glucocorticoid receptors and appear to inhibit kinase phosphorylation including MAPK and ERK1/2, NF-κB transcription factor induction/translocation, and DNA binding. They also inhibit pro-inflammatory mediators, TNF-α, IL-6, IL-8, ROS, and proteases such as MMP-9. Panax ginseng protects against oxidative stress by increasing anti-oxidative enzymes and reducing the production of oxidants.

CONCLUSION

Given that Panax ginseng and ginsenosides appear to inhibit processes related to COPD pathogenesis, they represent an attractive therapeutic target for the treatment of COPD.

Peripheral insulin resistance develops in transgenic rats overexpressing phosphoenolpyruvate carboxykinase in the kidney

AIMS/HYPOTHESIS

To study the secondary consequences of impaired suppression of endogenous glucose production (EGP) we have created a transgenic rat overexpressing the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) in the kidney. The aim of this study was to determine whether peripheral insulin resistance develops in these transgenic rats.

METHODS

Whole body rate of glucose disappearance (R(d)) and endogenous glucose production were measured basally and during a euglycaemic/hyperinsulinaemic clamp in phosphoenolpyruvate carboxykinase transgenic and control rats using [6-(3)H]-glucose. Glucose uptake into individual tissues was measured in vivo using 2-[1-(14)C]-deoxyglucose.

RESULTS

Phosphoenolpyruvate carboxykinase transgenic rats were heavier and had increased gonadal and infrarenal fat pad weights. Under basal conditions, endogenous glucose production was similar in phosphoenolpyruvate carboxykinase transgenic and control rats (37.4+/-1.1 vs 34.6+/-2.6 micromol/kg/min). Moderate hyperinsulinaemia (810 pmol/l) completely suppressed EGP in control rats (-0.6+/-5.5 micromol/kg/min, p<0.05) while there was no suppression in phosphoenolpyruvate carboxykinase rats (45.2+/-7.9 micromol/kg/min). Basal R(d) was comparable between PEPCK transgenic and control rats (37.4+/-1.1 vs 34.6+/-2.6 micromol/kg/min) but under insulin-stimulated conditions the increase in R(d) was greater in control compared to phosphoenolpyruvate carboxykinase transgenic rats indicative of insulin resistance (73.4+/-11.2 vs 112.0+/-8.0 micromol/kg/min, p<0.05). Basal glucose uptake was reduced in white and brown adipose tissue, heart and soleus while insulin-stimulated transport was reduced in white and brown adipose tissue, white quadriceps, white gastrocnemius and soleus in phosphoenolpyruvate carboxykinase transgenic compared to control rats. The impairment in both white and brown adipose tissue glucose uptake in phosphoenolpyruvate carboxykinase transgenic rats was associated with a decrease in GLUT4 protein content. In contrast, muscle GLUT4 protein, triglyceride and long-chain acylCoA levels were comparable between PEPCK transgenic and control rats.

CONCLUSIONS/INTERPRETATION

A primary defect in suppression of EGP caused adipose tissue and muscle insulin resistance.

Malonyl-CoA and AMP-activated protein kinase (AMPK): possible links between insulin resistance in muscle and early endothelial cell damage in diabetes

Based on available evidence, we would propose the following. (i) Excesses of glucose and free fatty acids cause insulin resistance in skeletal muscle and damage to the endothelial cell by a similar mechanism. (ii) Key pathogenetic events in this mechanism very likely include increased fatty acid esterification, protein kinase C activation, an increase in oxidative stress (demonstrated to date in endothelium) and alterations in the inhibitor kappa B kinase/nuclear factor kappa B system. (iii) Activation of AMP-activated protein kinase (AMPK) inhibits all of these events and enhances insulin signalling in the endothelial cell. It also enhances insulin action in muscle; however, the mechanism by which it does so has not been well studied. (iv) The reported beneficial effects of exercise and metformin on cardiovascular disease and insulin resistance in humans could be related to the fact that they activate AMPK. (v) The comparative roles of AMPK in regulating metabolism, signalling and gene expression in muscle and endothelial cells warrant further study.

The role of lipids in the pathogenesis of muscle insulin resistance and beta cell failure in type II diabetes and obesity

This review considers evidence for, and putative mechanisms of, lipid-induced muscle insulin resistance. Acute free fatty acid elevation causes muscle insulin resistance in a few hours, with similar muscle lipid accumulation as accompanies more prolonged high fat diet-induced insulin resistance in rodents. Although causal relations are not as clearcut in chronic human insulin resistant states such as obesity and type 2 diabetes, it is now recognised that muscle lipids also accumulate in these states. The classic Randle glucose-fatty acid cycle is only one of a number of mechanisms by which fatty acids might influence muscle glucose metabolism and insulin action. A key factor is seen to be accumulation of muscle long chain acyl CoAs, which could alter insulin action via several mechanisms including chronic activation of protein kinase C isoforms or ceramide accumulation. These interactions are fundamental to understanding metabolic effects of new insulin "sensitizers", e.g. thiazolidinediones, which alter lipid metabolism and improve muscle insulin sensitivity in insulin resistant states. Recent work has also pointed to a possible role of lipids in beta cell deterioration ("lipotoxicity") associated with type 2 diabetes.

Evidence that amylin stimulates lipolysis in vivo: a possible mediator of induced insulin resistance

The present study investigated the role of amylin in lipid metabolism and its possible implications for insulin resistance. In 5- to 7-h-fasted conscious rats, infusion of rat amylin (5 nmol/h for 4 h) elevated plasma glucose, lactate, and insulin (P <0.05 vs. control, repeated-measures ANOVA) with peak values occurring within 60 min. Despite the insulin rise, plasma nonesterified fatty acids (NEFA) and glycerol were also elevated (P < 0.001 vs. control), and these elevations (80% above basal) were sustained over the 4-h infusion period. Although unaltered in plasma, triglyceride content in liver was increased by 28% (P < 0.001) with a similar tendency in muscle (18%, P = 0.1). Infusion of the rat amylin antagonist amylin-(8-37) (125 nmol/h) induced opposite basal plasma changes to amylin, i.e., lowered plasma NEFA, glycerol, glucose, and insulin levels (all P < 0.05 vs. control); additionally, amylin-(8-37) blocked amylin-induced elevations of these parameters (P < 0.01). Treatment with acipimox (10 mg/kg), an anti-lipolytic agent, before or after amylin infusion blocked amylin's effects on plasma NEFA, glycerol, and insulin but not on glucose and lactate. We conclude that amylin could exert a lipolytic-like action in vivo that is blocked by and is opposite to effects of its antagonist amylin-(8-37). Further studies are warranted to examine the physiological implications of lipid mobilization for amylin-induced insulin resistance.

Peroxisome proliferator-activated receptor (PPAR)-alpha activation lowers muscle lipids and improves insulin sensitivity in high fat-fed rats: comparison with PPAR-gamma activation

Peroxisome proliferator-activated receptor (PPAR)-alpha agonists lower circulating lipids, but the consequences for muscle lipid metabolism and insulin sensitivity are not clear. We investigated whether PPAR-alpha activation improves insulin sensitivity in insulin-resistant rats and compared the effects with PPAR-gamma activation. Three-week high fat-fed male Wistar rats were untreated or treated with the specific PPAR-alpha agonist WY14643 or the PPAR-gamma agonist pioglitazone (both 3 mg x kg(-1) x day(-1)) for the last 2 weeks of high-fat feeding. Like pioglitazone, WY14643 lowered basal plasma levels of glucose, triglycerides (-16% vs. untreated), and leptin (-52%), and also muscle triglyceride (-34%) and total long-chain acyl-CoAs (LCACoAs) (-41%) (P < 0.05). In contrast to pioglitazone, WY14643 substantially reduced visceral fat weight and total liver triglyceride content (P < 0.01) without increasing body weight gain. WY14643 and pioglitazone similarly enhanced whole-body insulin sensitivity (clamp glucose infusion rate increased 35 and 37% and glucose disposal 22 and 15%, respectively, vs. untreated). Both agents enhanced insulin-mediated muscle glucose metabolic index (Rg') and reduced muscle triglyceride and LCACoA accumulation (P < 0.05). Although pioglitazone had more potent effects than WY14643 on muscle insulin sensitization, this was associated with its greater effect to reduce muscle LCACoA accumulation. Overall insulin-mediated muscle Rg' was inversely correlated with the content of LCACoAs (r = -0.74, P = 0.001) and with plasma triglyceride levels (r = -0.77, P < 0.001). We conclude that even though WY14643 and pioglitazone, representing PPAR-alpha and PPAR-gamma activation, respectively, may alter muscle lipid supply by different mechanisms, both significantly improve muscle insulin action in the high fat-fed rat model of insulin resistance, and this effect is proportional to the degree to which they reduce muscle lipid accumulation.

Nonshivering thermogenesis in a marsupial (the tasmanian bettong Bettongia gaimardi) is not attributable to brown adipose tissue

The Tasmanian bettong (Bettongia gaimardi, a marsupial) is a rat-kangaroo that increases nonshivering thermogenesis (NST) in response to norepinephrine (NE). This study attempted to assess whether brown adipose tissue (BAT), a specialized thermogenic effector, is involved in NST in the bettong. Regulatory NST, indicated by resting oxygen consumption (Vo2) of the whole body, was measured under conscious conditions at 20 degrees C with various stimuli: cold (4 degrees -5 degrees C) or warm (25 degrees C) acclimation, NE injection, and the beta3-adrenoceptor agonist (BRL) 37344. In line with the functional studies in vivo, the presence of BAT was evaluated by examining the expression of the uncoupling protein 1 (UCP1) with both rat cDNA and oligonucleotide probes. Both NE and BRL 37344 significantly stimulated NST in the bettong. After cold acclimation of the animals (at 4 degrees -5 degrees C for 2 wk), the resting Vo2 was increased by 15% and the thermogenic effect of NE was enhanced; warm-acclimated animals showed a slightly depressed response. However, no expression of UCP1 was detected in bettongs either before or after cold exposure (2 wk). These data suggest that the observed NST in the marsupial bettong is not attributable to BAT.

Altered muscle metabolism associated with vasoconstriction in spontaneously hypertensive rats

In the rat muscle vascular bed, vasoconstrictors either increase or decrease oxygen consumption (VO2). The present study compared the effects of norepinephrine (NE), angiotensin II (ANG II), and 5-hydroxytryptamine (5-HT) on vasoconstriction-associated metabolism in the constant-flow perfused hindlimb of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) in the absence of insulin. Basal perfusion pressure, VO2, glucose uptake, and lactate production were increased by 21.4, 11.9, 46.4, and 44.9% (P < 0.05 for all), respectively, in SHR, which also had higher blood pressure and metabolic rate (P < 0.05) in vivo. Dose-response curves for NE-induced perfusion pressure, VO2, and lactate production in SHR were shifted to the left compared with WKY. Associated with the increased perfusion pressure, NE-induced VO2 and glucose uptake were both decreased (P < 0.01), particularly at high concentrations. These differences were unaffected by 10 microM propranolol but were all diminished by further addition of prazosin (2.5 nM). ANG II stimulated VO2, glucose uptake, and lactate production in both strains, but the increased lactate production was smaller in SHR (P < 0.05) with a proportional decrease (P < 0.05) in glucose uptake. Conversely, 5-HT decreased VO2 in both strains (P < 0.01), and this effect was greater in SHR (P < 0.01). These data suggest that SHR muscle thermogenesis and glucose uptake are impaired during vasoconstriction, especially in response to NE.

Improved folding yields of a model protein using protein disulfide isomerase

PURPOSE

To study the effects of recombinant human protein disulfide isomerase (rhPDI) concentration, reduced glutathione:oxidized glutathione ratio (GSH:GSSG) and temperature on the efficiency of oxidative folding of a model protein, recombinant human interleukin 2 (C125A mutation) (C125A rhIL-2).

METHODS

C 125A rhIL-2 inclusion bodies were reduced and denatured by guanidium hydrochloride (Gdm.Cl) and 100 mM GSH. The solution was diluted 10 times into folding buffer, allowing C125A rhIL-2 to fold either in the absence or presence of rhPDI. The renatured and unfolded C125A rhIL-2 species were quantitated by reversed phase-HPLC.

RESULTS

The initial folding rate of C125A rhIL-2 linearly increased with rhPDI:C125A rhIL-2 molar ratio in the first 2.5 minutes, and reached the highest rate when the rhPDI:C125A rhIL-2 ratio was 1:1. The oxidative folding of C125A rhIL-2 linearly increased as the GSH:GSSG molar ratio decreased from 10:0 to 10:3. The folding of C125A rhIL-2 was also dependent on temperature, and optimum folding was realized at 23 degrees C.

CONCLUSIONS

These results demonstrate that under optimal redox potential and temperature, rhPDI enhances the oxidative folding of C125A rhIL-2. In the oxidative folding of C125A rhIL-2, rhPDI exerts its effect on folding by the acceleration of thiol/disulfide interchange.

Changes in functional expression of alpha-1 adrenoceptors in hindlimb vascular bed of spontaneously hypertensive rats and their effects on oxygen consumption

Norepinephrine (NE) induces a sigmoidal dose-response curve for perfusion pressure and a bell-shaped curve for oxygen consumption (VO2) in the constant-flow perfused hindlimb of Wistar rats. These effects are now described in spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto rats (WKY). In SHR, the pressure curve was shifted left- and upward whereas the VO2 curve was shifted left- but downward, when compared with WKY. In the presence of 10 microM propranolol, prazosin (2.5 nM) shifted the pressure and VO2 curves much more than yohimbine (0.1 microM) to the right in both strains and its effects were greater in SHR, suggesting that these effects were mediated largely by alpha-1 receptors, particularly in SHR. In the presence of propranolol plus yohimbine, the pressure curve was markedly shifted to the right by both the selective alpha-1A-antagonist 5-methylurapidil (3.3 nM), and by the alpha-1D antagonist BMY 7378 (0.1 microM) or SK&F 105854 (2 microM) in SHR but not in WKY. With respect to the VO2 curve, 5-methylurapidil attenuated the descending limb without affecting the ascending limb. Similar effects were also obtained with another alpha-1A antagonist 1 nM KMD-3213 in both SHR and WKY. In contrast, BMY and SK&F markedly inhibited the ascending limb of the VO2 curve. These results indicate that both alpha-1A- and alpha-1D subtypes are functionally up-regulated in SHR muscle vascular bed where the ascending limb of VO2 is predominantly mediated by the alpha-1D at a much lower concentration for NE than the descending limb which is predominantly mediated by the alpha-1A subtype.

Effects of noradrenaline and flow on lactate uptake in the perfused rat hindlimb

Skeletal muscle can release or take up lactate depending on the lactate concentration gradient across the cell membrane. In the perfused rat hindlimb without arterial lactate, both noradrenaline (NA) infusion and increased flow promote lactate release and oxygen consumption (VO2). However, it is unclear whether NA or increased flow rate have similar effects on lactate uptake. The present study compares these effects in the rat hindlimb perfused at a basal flow rate of 0.33 mL min-1 g-1 and 25 degrees C in the presence of added arterial lactate. When 10 mmol L-1 L-(+)-lactate was added to the arterial perfusate, lactate was taken up (16 +/- 1.0 mumol g-1 h-1, n = 13) by the hindlimb with a 35% higher VO2 than that without added lactate. Doubling perfusion flow rate enhanced lactate uptake and VO2 by 120% and 40%, respectively. Glucose uptake was also increased (by 253%) with increased flow. Infusion of NA increased perfusion pressure, VO2 and glucose uptake similarly to those induced by increased flow rate. However, lactate uptake was inhibited by NA. This inhibition was not altered by the beta-adrenergic antagonist propranolol. Vasopressin also showed similar effects to NA to decrease lactate uptake associated with increased VO2 and vasoconstriction. These data indicate that in the presence of a high arterial lactate concentration, NA has opposite effects from increased flow rate on skeletal muscle lactate uptake although both have similar effects on lactate release in the absence of arterial lactate. Inhibition of lactate uptake may relate to the vasoconstrictive action of NA.

Sympathetic stimulation elicits increased or decreased VO2 in the perfused rat hindlimb via alpha 1-adrenoceptors

The effects of lumbar sympathetic nerve stimulation on oxygen uptake (VO2) in curarized muscle of the perfused rat hindlimb were investigated. Stimulation of sympathetic nerves elicited vasoconstriction at all frequencies. Importantly, this was associated with changes in VO2 that were generally stimulatory at low frequencies (0.5-2 Hz) and inhibitory at high frequencies (5-10 Hz). Both the pressor response and the changes in VO2 were almost completely blocked by the alpha 1/alpha 2-blocker phentolamine (1.0 microM) but were not affected by the beta 1/beta 2-blocker DL-propranolol (2.0 microM). The alpha 2-blocker yohimbine (0.1 microM) did not significantly affect either the pressor or VO2 response. The alpha 1-antagonist prazosin (0.1 microM) abolished the vasoconstriction with low-frequency stimulation and inhibited > 90% of the vasoconstriction with high-frequency stimulation. Intra-arterial infusion of phenylephrine (alpha 1-agonist), but not of UK-14304 (alpha 2-agonist), also elicited a similar biphasic response in VO2 during vasoconstriction. The changes in VO2 at both low- and high-frequency stimulation were fully reversed by prazosin. The vasodilator sodium nitroprusside also showed similar effects to prazosin in blocking both VO2 and vasoconstriction. Thus sympathetic control of VO2 in the perfused rat hindlimb appears to be initiated by activation of predominantly vascular alpha 1-adrenoceptors.

Alpha-adrenergic stimulation of thermogenesis in a rat kangaroo (Marsupialia, Bettongia gaimardi)

The Tasmanian bettong (Bettongia gaimardi) is a small rat kangaroo without detectable brown adipose tissue (BAT). In view of our previous findings of norepinephrine-mediated increase in O2 consumption (Vo2) in the perfused hindlimb of this species, the present study examined the effect of alpha-adrenoceptors on the thermogenesis of conscious bettongs at rest by infusing adrenergic agents via an indwelling catheter in the tail vein. The resting Vo2 was 22.9 +/- 1.9 mmol.kg-1.h-1. Norepinephrine (10-80 micrograms.kg-1.min-1) stimulated Vo2 in a dose-dependent manner with the maximal increment of 46.7%. Naphazoline (an alpha 1,alpha 2-adrenergic agonist) and phenylephrine (an alpha 1-adrenergic agonist) also elicited increases in Vo2 with maximal values of 29.6 and 34.8%, respectively. In contrast, the alpha 2-adrenergic agonist clonidine had no significant effects. Both alpha- and beta-adrenergic blockers were used to antagonize the submaximal increase in Vo2 elicited by norepinephrine. As a dose of 10 micrograms.kg-1.min-1, the alpha-adrenergic blocker phentolamine abolished the effects of naphazoline and phenylephrine and reduced norepinephrine-induced Vo2 by 45.5%. The beta-adrenergic blocker propranolol inhibited the norepinephrine-induced Vo2 by 58.8% at 20 micrograms.kg-1.min-1. A combination of the two antagonists blocked 82.5% of the norepinephrine-induced Vo2. Pretreatment of the animal with indomethacin (1 mg/kg), a known inhibitor of prostaglandin cyclooxygenase, had no effect on phenylephrine-elicited Vo2. Taken together, these results indicate that alpha 1-adrenoceptors are directly involved in norepinephrine-induced thermogenesis in non-BAT tissue(s).

Degradation of antiflammin 2 under acidic conditions

Antiflammin 2 (HDMNKVLDL, AF2) is a synthetic peptide derived from the region of highest sequence similarity of lipocortin I and uteroglobin, and is a potent antiinflammatory agent without any known side effects of corticosteroids. The antiinflammatory activity of AF2 has been demonstrated, but is not reproducible between laboratories. It has been suggested that the chemical instability of this peptide is responsible for the loss of activity. The degradation of AF2 in aqueous solutions at a pH range of 3 to 10 has been reported. In this study, the degradation of AF2 at acidic pHs was monitored by reversed-phase HPLC. The reactions were studied as functions of buffer concentration and temperature. The rates of loss of AF2 followed apparent pseudo-first-order kinetics. Several products were isolated and identified by fast atom bombardment mass spectroscopy and tandem mass spectroscopy, and were the result of C- and N-terminus hydrolyses of aspartyl peptide bonds in AF2. The peptide bonds at C-termini of the aspartyl residues were most susceptible to hydrolysis, resulting in the formation of major degradation products, HDMNKVLD, MNKVLDL, and MNKVLD. The minor products from the N-terminus hydrolysis were HDMNKVL and MNKVL and formed at much slower rates.

Covalent association of protein disulfide isomerase with recombinant human interleukin 2 in vitro

Protein disulfide isomerase has broad specificity in the catalysis of the formation and rearrangement of native disulfide bonds in proteins. This enzyme has two independent thioredoxin-like active sites (-CGHC-) and a peptide binding site. However, the mechanisms involving the catalytic processes are not clearly understood. It was reported that the enzyme associates with scrambled pancreatic ribonuclease A in vitro, and with misfolded human lysozyme in vivo. In the present study, recombinant human interleukin 2 has been chosen to probe the reaction intermediate in the reaction with the enzyme. We have identified and characterized a covalent associate formed in vitro by SDS-PAGE and Western blot analysis. This associate has a molecular weight of 71-72 kDa, the approximate sum of the molecular weights of the enzyme and the substrate. Western blot analysis confirmed that it formed via an intermolecular disulfide bond. Upon treatment with 2-mercaptoethanol, this bond was cleaved.

Oxidative degradation of antiflammin 2

PURPOSE

To study the oxidation of the methionine residue of antiflammin 2 (HDMNKVLDL, AF2) as a function of pH, buffer concentration, ionic strength, and temperature using different concentrations of hydrogen peroxide and to determine the accessibility of methionine residue to oxidation.

METHODS

Reversed-phase high-performance liquid chromatography (RPHPLC) was used as the main analytical method in determining the oxidation rates of AF2. Calibration curves for AF2 and the oxidation product, methionine sulfoxide of AF2 (Met(O)-3-AF2), were constructed for each measurement using standard materials. Fast Atom Bombardment Mass Spectroscopy (FABMS) was used to characterize the product.

RESULTS

Met(O)-3-AF2 was the only oxidation product detected at pH 3.0 to 8.0. The oxidation rates were independent of buffer concentrations, ionic strength, and pH from 3.0 to 7.0. However, there was an acceleration of the rates at basic pHs, and small amounts of degradation products other than Met(O)-3-AF2 were observed in this alkaline region.

CONCLUSIONS

Oxidation of methionine in AF2 does not cause the biological inactivation reported by other laboratories since this drug is relatively stable under neutral conditions in the absence of oxiding agent.

Constant-pressure perfusion of rat hindlimb shows alpha- and beta-adrenergic stimulation of oxygen consumption

Isolated rat hindlimbs were perfused at 37 degrees C and constant physiological pressure (80 +/- 0.5 mmHg) while the flow rate that was allowed to freely self-adjust was monitored. Under these conditions, evidence was obtained for both alpha- and beta-adrenergic stimulation of oxygen consumption (VO2) in contrast to constant-flow perfusion, which has only convincingly shown alpha-adrenergic stimulation of VO2 in response to adrenergic agents. Addition of norepinephrine (NE; 1-33 nM) led to an increase in VO2 with a maximum of 29% above the basal value at 3.3 nM, even though the flow rate decreased. Phenylephrine (3.3-33 nM) and vasopressin (10-100 pM) also showed similar, but lesser in magnitude, vasoconstriction-associated stimulatory effects on VO2. Prazosin (an alpha 1-antagonist) completely reversed the NE-mediated decrease in flow rate and significantly blocked the increased VO2. In contrast, isoproterenol (10-1,000 nM) increased both flow rate (30%) and VO2 (32%). The isoproterenol-stimulated VO2 was not blocked by the beta 1-, beta 2-antagonist propranolol (10 microM), although the increased flow was reversed. In the presence of propranolol (1 or 10 microM), BRL-35135A (a beta 3-agonist) also stimulated VO2 (18%) without significant change in flow rate. These results lend further support to the role of the alpha 1-adrenoceptor in muscle VO2. In addition there is evidence for the presence of a functional beta 3-adrenoceptor as an additional subtype responsible for NE-mediated thermogenesis in the rat hindlimb.

Vasoconstrictors alter oxygen, lactate, and glycerol metabolism in the perfused hindlimb of a rat kangaroo

The Tasmanian bettong (Bettongia gaimardi) is a small marsupial rat kangaroo without detectable brown adipose tissue (BAT). The hindlimb was perfused with constant flow at 25 degrees C after cannulation under anesthesia of the femoral artery and vein to one hindlimb. Norepinephrine (NE, 25 nM-2.5 microM) and vasopressin (VP, 10 nM-0.1 microM) each increased perfusion pressure, oxygen consumption (VO2), and lactate and glycerol efflux of the perfused hindlimb. NE-mediated increases in VO2 and the efflux of lactate and glycerol were unaffected by propranolol (10 microM) but were completely blocked by the further addition of phentolamine (10 microM). In contrast, serotonin (5-HT; 0.1-2.5 microM) inhibited VO2 and inhibited lactate efflux. The changes induced by NE, VP, and 5-HT were all rapidly reversed by nitroprusside. These results suggest that resting thermogenesis in bettong hindlimb can be differentially controlled by the vasculature, which may also contribute to the induced VO2. This vascular control of skeletal muscle VO2 appears widespread in homeotherm evolution.

[Effect of Leontopodium leontopodioides (Willd.) Beauv. on inflammation induced by animal reversed passive arthus (RPA)]

The extract from Leontopodium leontopodioides 50-100mg/kg ip has been proved able to suppress the swelling of normal or adrenalectomised rat hind paws induced by RPA, and strongly inhibit the cutaneous hemorrhage of animals induced by RPA, lysosome or lysosome of broken membrane. It has also been shown that the extract 100 mg/kg ip can markedly inhibit the migration of leukocytes. These suggest that the anti-inflammatory properties of the extract are not dependent on the pituitary-adrenal system or membrane of lysosome.

Norephedrine (phenylpropanolamine) stimulates oxygen consumption and lactate production in the perfused rat hindlimb

d,l-Norephedrine (phenylpropanolamine) which is both a demethylated analogue and a metabolite of d,l-ephedrine, is a reputed anorectic agent. In the present study the proposed most active isomer of this mixture, l-norephedrine has been assessed as a peripherally acting thermogenic agent in the isolated perfused rat hindlimb. l-Norephedrine produced a dose-dependent increase in oxygen uptake and perfusion pressure and increased lactate production. Whereas propranolol potentiated the increase in oxygen uptake and perfusion pressure produced by l-norephedrine, prazosin significantly and nitroprusside totally inhibited both of these changes. Nitroprusside also completely inhibited the increase in lactate production. We conclude that norephedrine has a hitherto unrecognized peripheral thermogenic activity in the perfused rat hindlimb resulting from its interaction with alpha 1 adrenergic receptors that control vasoconstriction in this tissue.

Release of purine and pyrimidine nucleosides and their catabolites from the perfused rat hindlimb in response to noradrenaline, vasopressin, angiotensin II and sciatic-nerve stimulation

Uric acid and uracil were released at constant rates (0.95 and 0.4 nmol/min per g respectively) by the perfused rat hindlimb. Noradrenaline, vasopressin or angiotensin II further increased the release of these substances 2-5-fold, coinciding with increases in both perfusion pressure (vasoconstriction) and O2 uptake. The hindlimb also released, but in lesser amounts, uridine, hypoxanthine, xanthine, inosine and guanosine, and all but hypoxanthine and guanosine were increased during intense vasoconstriction. Uric acid and uracil releases were increased by noradrenaline in a dose-dependent manner. However, the release of these substances did not fully correspond with the dose-dependent increase in O2 uptake and perfusion pressure, where changes in the latter occurred at lower doses of noradrenaline. Sciatic-nerve stimulation (skeletal-muscle contraction) did not increase the release of uracil, uric acid or uridine, but instead increased the release of inosine (7-fold) and hypoxanthine (2-fold). Since the UTP content as well as the UTP/ATP ratio are higher in smooth muscle than in skeletal muscle, it is proposed that release of uric acid and uracil arises from increased metabolism of the respective adenosine and uridine nucleotides during intense constriction of smooth muscle.

Capsaicin and dihydrocapsaicin stimulate oxygen consumption in the perfused rat hindlimb

The capsaicinoid spice principles capsaicin and dihydrocapsaicin were shown to be thermogenic in the isolated rat hindlimb perfused with constant flow. Both principles elicited similar maximal increases in oxygen consumption (VO2) and perfusion pressure. For capsaicin, the mean maximal increase in VO2 was 1.39 +/- 0.28 mumol/g h or 23 per cent with a perfusion pressure increase of 15.8 +/- 2.8 mmHg, or 54.5 per cent. Dihydrocapsaicin increased VO2 by 1.13 +/- 0.24 or 20 per cent and a perfusion pressure rise of 14.2 +/- 5.0 mmHg or 49 per cent. Above 0.8 microM of either capsaicinoid there was inhibition of oxygen consumption after transient stimulation. Concurrent infusion of the adrenergic antagonists prazosin (alpha 1) and propranolol (beta) had little or no effect on the actions of either capsaicin or dihydrocapsaicin, nor did division of the somatic nerves to the hindlimb. These results indicate a local site of action of these principles in the hindlimb not mediated by a secondary release of catecholamines. Increases in both VO2 and pressure were significantly blocked by the vasodilator nitroprusside. This is in agreement with our previous findings that nitroprusside can block the effects of angiotensin, vasopressin and flow-induced increases in VO2 and perfusion pressure in the perfused hindlimb. The present findings suggest that capsaicin and dihydrocapsaicin can be thermogenic in the rat and that the mechanism of action directly involves vasoconstriction in some manner. We have previously suggested that there might be significant direct smooth muscle vascular consumption of oxygen during sustained vasoconstriction. The findings with capsaicin and dihydrocapsaicin are consistent with this hypothesis.

Flow-induced oxygen uptake by the perfused rat hindlimb is inhibited by vasodilators and augmented by norepinephrine: a possible role for the microvasculature in hindlimb thermogenesis

Oxygen uptake in the perfused rat hindlimb was studied at 25 degrees C using an artificial perfusate, and the effects of perfusate flow rate, norepinephrine, and vasodilators were compared. Hindlimb oxygen uptake and perfusion pressure each increased as the flow rate was increased stepwise from 2 to 18.5 mL/min per hindlimb. At each flow rate, the rate of oxygen uptake was inhibited by the vasodilator nitroprusside (0.5 mM) and increased by norepinephrine (5 nM). A corresponding change in perfusion pressure also occurred, with norepinephrine leading to a marked increase and nitroprusside leading to a decrease; however, changes in oxygen uptake and pressure were not linearly related. The lactate/pyruvate ratio of the perfusate was used as an index of tissue perfusion and was determined at each flow rate. Lactate and pyruvate efflux increased as the flow rate was increased stepwise from 2 to 18.5 mL/min per hindlimb. At 2 mL/min per hindlimb, the lactate/pyruvate ratio was 15; at flow rates equal or greater than 4 mL/min per hindlimb, the ratio was constant at 9. Nitroprusside had no significant effect on the ratio at any flow rate even though a marked inhibitory effect on oxygen uptake was evident. Muscle content of high energy phosphates at 8 mL/min per hindlimb did not differ before and after treatment with vasodilators. In addition, the vasodilators had no apparent effect on skeletal muscle oxygen uptake or force development during electrical stimulation. The findings indicate that oxygen uptake by the hindlimb is not limited by inadequate perfusion and that oxygen uptake can be further increased by norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition by vasodilators of noradrenaline and vasoconstrictor-mediated, but not skeletal muscle contraction-induced oxygen uptake in the perfused rat hindlimb; implications for non-shivering thermogenesis in muscle tissue

1. The effect of noradrenaline as well as of vasopressin and angiotensin II to increase oxygen uptake and perfusion pressure by the isolated perfused rat hindlimb were completely inhibited by the vasodilators, nitroprusside (0.5 mM), nifedipine (2.5 microM) and isoprenaline (50 nM). 2. Oxygen uptake due to sciatic nerve stimulation of skeletal muscle contraction was not inhibited by 0.5 mM nitroprusside but was found to increase further that produced by a maximum dose of either noradrenaline or angiotensin II. 3. Analysis of high energy phosphates in samples of freeze-clamped hindlimb muscle showed no difference before and after vasoconstrictor addition or with muscle sampled in vivo. 4. It is concluded that norepinephrine mediated increase in oxygen uptake by the perfused rat hindlimb results from its vasoconstrictor action.

A comparison of vasopressin and noradrenaline on oxygen uptake by perfused rat hindlimb, kidney, intestine and mesenteric arcade suggests that it is in part due to contractile work by blood vessels

1. The rat hindlimb, kidney and intestine were each perfused in a nonrecirculating mode at 25 degrees C using an artificial perfusate (initial pressure 85 +/- 5 mmHg) and the effects of vasopressin and noradrenaline on oxygen uptake and perfusion pressure determined. 2. Both vasopressin (K0.5 = 0.1 nM) and noradrenaline (K0.5 = 2 nM) increased oxygen uptake as well as perfusion pressure by the perfused hindlimb; changes in oxygen uptake were closely matched by changes in pressure. The maximum increase in oxygen uptake was approx. 9 mumol/hr per g wet wt of hindlimb. 3. The perfused kidney also responded to vasopressin and noradrenaline with parallel increases in oxygen uptake and perfusion pressure for each agent. The largest increase in oxygen uptake was approx. 30 mumol/hr per g wet wt but this was not maximal. 4. Vasopressin increased oxygen uptake and pressure by the perfused intestine over the range 0.01-2 nM, but the changes in pressure only became significant at doses greater than 0.1 nM. 5. Noradrenaline inhibited oxygen uptake and increased perfusion pressure in a dose-dependent manner at pharmacological concentrations (greater than 30 nM) when shunting of perfusate may have contributed to unperfused regions. 6. A network of mesenteric blood vessels estimated to contain approx. 6% vascular tissue by weight, with the remainder white fat cells, lymphatics and connective tissue, was also perfused. 7. Vasopressin (K0.5 = 0.3 nM) and noradrenaline (K0.5 = 30 nM) each increased oxygen uptake and perfusion pressure in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of myocardial reperfusion injury with free radical scavengers. An experimental study

The changes in endogenous superoxide dismutase (ESOD) during myocardial ischemia and reperfusion and the efficacy of oxygen free radical scavengers in myocardial protection were investigated in an isolated heart model connected with the recirculating nonpulsatile perfusion circuit. Subjected to a 2-hour period of global ischemia (27 C), the heart was reperfused with 37 C oxygen diluted auto-blood for 60 minutes. Superoxide dismutase plus catalase was added into the cardioplegic solution and reperfusates. ESOD activity was measured by pyrogallol method. The results of the experiment showed that ESOD activity after ischemia and reperfusion was decreased and the addition of oxygen free radical scavengers (SOD and CAT) to the cardioplegic solution and the reperfusates greatly reduced the leakage of myocardial enzymes, coronary vascular resistance, and the ultrastructural damages of the myocardium. These results suggest that the use of SOD and CAT may inhibit myocardial reperfusion injury by scavenging oxygen-derived free radicals.

Vasopressin and angiotensin II stimulate oxygen uptake in the perfused rat hindlimb

Vasopressin and angiotensin II markedly stimulated oxygen uptake in the perfused rat hindlimb. The increase due to each agent approached 70% of the basal rate, and was greater than that produced by a maximal concentration of norepinephrine. Half-maximal stimulation occurred at 60 pM vasopressin, 0.5 nM angiotensin II and 10 nM norepinephrine. Angiotensins I and III were less potent than angiotensin II. For each agent, the dose-dependent increase in oxygen uptake coincided with a dose-dependent increase in perfusion pressure. The effects of both vasopressin and angiotensin to increase oxygen uptake and pressure were not inhibited by either phentolamine, propranolol or a combination of the two, but were completely inhibited by the vasodilator, nitroprusside. Nitroprusside also inhibited flow-induced increases in hindlimb oxygen uptake and perfusion pressure. The findings indicate a key role for the vascular system in the control of hindlimb oxygen uptake.

Screening salt-tolerant barley genotypes via F1 anther culture in salt stress media

Anthers of two six-row barley cultivars Diamond (a germination salt sensitive cultivar) and Men Yuan Liang Lan (a germination salt tolerant cultivar), and their F1 reciprocal crosses were cultured in liquid media containing 0, 0.4, 0.6, and 0.8% Na2SO4. A total of 138 green pollen plants were obtained: 7 from Na2SO4 media, 128 from Na2SO4 free medium. Seeds of two successive generations of 61 pollen plants were germinated in a series of Na2SO4 solution (0 to 5.5%). It was found that among 37 progenies from F1 pollen in Na2SO4 free medium, 11 were as sensitive as "Diamond", 12 were intermediate to the two parents, 7 were equal to the salt tolerant parent and 7 were more tolerant to Na2SO4 than 'Men Yuan Liang Lan'. Whereas, no progeny from F1 pollen in high salt media was as susceptible as the susceptible parent; 2 were intermediate, 2 were equal to the salt tolerant parent and 2 were more tolerant than the salt tolerant parent. The results indicate that culturing anthers in Na2SO4 media effectively eliminated salt susceptible progenies. All 16 microspore-derived lines of Diamond were as susceptible as 'Diamond' to Na2SO4. The 5 lines from 'Men Yuan Liang Lan' microspores were as resistant to Na2SO4 as 'Men Yuan Liang Lan'. All of the lines breed-true. The results indicate that the lines exhibiting elevated levels of tolerance to salt probably resulted from recombination of genes rather than from spontaneous mutation.