Altered skeletal muscle glucose transport and blood lipid levels in habitual cigarette smokers

Albumin knockout mice exhibit reduced plasma free fatty acid concentration and enhanced insulin sensitivity

Circulating albumin is expected to play a significant role in the trafficking of plasma free fatty acids (FFA) between tissues, such as FFA transfer from adipose tissue to the liver. However, it was not yet known how disrupting FFA binding to albumin in circulation would alter lipid metabolism and any resulting impacts upon control of glycemia. To improve understanding of metabolic control, we aimed to determine whether lack of serum albumin would decrease plasma FFA, hepatic lipid storage, whole body substrate oxidation, and glucose metabolism. Male and female homozygous albumin knockout mice and C57BL/6J wild type controls, each on a standard diet containing a moderate fat content, were studied at 6-8 weeks of age. Indirect calorimetry, glucose tolerance testing, insulin tolerance testing, exercise performance, plasma proteome, and tissue analyses were performed. In both sexes of albumin knockout mice compared to the wild type mice, significant reductions (p < 0.05) were observed for plasma FFA concentration, hepatic triacylglycerol and diacylglycerol content, blood glucose during the glucose tolerance test, and blood glucose during the insulin tolerance test. Albumin deficiency did not reduce whole body fat oxidation over a 24-h period and did not alter exercise performance in an incremental treadmill test. The system-level phenotypic changes in lipid and glucose metabolism were accompanied by reduced hepatic perilipin-2 expression (p < 0.05), as well as increased expression of adiponectin (p < 0.05) and glucose transporter-4 (p < 0.05) in adipose tissue. The results indicate an important role of albumin and plasma FFA concentration in lipid metabolism and glucoregulation.

Efficacy of therapeutic fasting and plant-based diet in patients with rheumatoid arthritis (NutriFast): study protocol for a randomised controlled clinical trial

BACKGROUND

Previous studies have shown beneficial effects of therapeutic fasting and plant-based dietary interventions on disease activity in patients with rheumatoid arthritis (RA) for a duration of up to 1 year. To date, the effects of such interventions on the gut microbiome and on modern diagnostic markers in patients with RA have not been studied. This trial aims to investigate the clinical effects of therapeutic fasting and a plant-based diet in patients with RA, additionally considering current immunological diagnostic tools and microbiome analyses.

METHODS/DESIGN

This trial is an open-label, single-centre, randomised, controlled, parallel-group clinical trial. We will randomly assign 84 patients with RA under a stable standard therapy to either (1) therapeutic fasting followed by a plant-based dietary intervention or (2) to a conventional nutritional counselling focusing on an anti-inflammatory dietary pattern according to the recommendations of the Deutsche Gesellschaft für Ernährung (German society for nutrition). Primary outcome parameter is the group difference from baseline to 12 weeks on the Health Assessment Questionnaire (HAQ). Other secondary outcomes include established clinical criteria for disease activity and treatment response in RA (Disease Activity Score 28, Simple Disease Activity Index, ACR-Response Criteria), changes in self-reported health and physical functional ability, mood, stress, quality of life, dietary behaviour via 3-day food records and a modified Food Frequency Questionnaire, body composition, changes in the gut microbiome, metabolomics and cytometric parameters. Outcomes will be assessed at baseline and day 7, after 6 weeks, 12 weeks and after 6 months.

ETHICS AND DISSEMINATION

Ethical approval to process and analyse data, and to publish the results was obtained through the institutional review board of Charité-Universitätsmedizin Berlin. Results of this trial will be disseminated through peer-reviewed publications and scientific presentations.

TRIAL REGISTRATION NUMBER

NCT03856190.

Plasma Free Fatty Acid Concentration as a Modifiable Risk Factor for Metabolic Disease

Plasma free fatty acid (FFA) concentration is elevated in obesity, insulin resistance (IR), non-alcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), and related comorbidities such as cardiovascular disease (CVD). Furthermore, experimentally manipulating plasma FFA in the laboratory setting modulates metabolic markers of these disease processes. In this article, evidence is presented indicating that plasma FFA is a disease risk factor. Elevations of plasma FFA can promote ectopic lipid deposition, IR, as well as vascular and cardiac dysfunction. Typically, elevated plasma FFA results from accelerated adipose tissue lipolysis, caused by a high adipose tissue mass, adrenal hormones, or other physiological stressors. Reducing an individual’s postabsorptive and postprandial plasma FFA concentration is expected to improve health. Lifestyle change could provide a significant opportunity for plasma FFA reduction. Various factors can impact plasma FFA concentration, such as chronic restriction of dietary energy intake and weight loss, as well as exercise, sleep quality and quantity, and cigarette smoking. In this review, consideration is given to multiple factors which lead to plasma FFA elevation and subsequent disruption of metabolic health. From considering a variety of medical conditions and lifestyle factors, it becomes clear that plasma FFA concentration is a modifiable risk factor for metabolic disease.

Reduced skeletal muscle endurance and ventilatory efficiency during exercise in adult smokers without airflow obstruction

In adult smokers without airflow obstruction, the contributions of pulmonary and skeletal muscle functions to reduced exercise capacity are unclear. We found that non-COPD smokers had decreased exercise capacity and muscle endurance although strength was preserved compared with never-smoking controls. Exercise endurance was associated with quadriceps endurance and CO transfer factor. Despite similar physical activity levels, smokers developed leg fatigue, breathlessness, and displayed increased ventilation with reduced ventilatory efficiency at lower workloads, without exhibiting ventilatory constraint.

Interaction of smoking and obesity on type 2 diabetes risk in a Chinese cohort

The aim of this study was to examine the independent and combined effects of current smoking and obesity on risk of type 2 diabetes (T2DM) in a Chinese cohort. We analyzed the data from a population-based prospective cohort of 3598 participants aged 35-74 years from Jiangsu, China. A Cox proportional hazards regression model was used to calculate the hazard ratio (HR) of T2DM and corresponding 95% confidence interval (CI), and to examine the interaction between current smoking and obesity on risk of T2DM. Compared with non-smokers, the hazard ratio of T2DM for current smokers was 4.16 (2.77-6.24). There was a significant interaction between current smoking and abdominal obesity on T2DM. RERI=2.84 (0.02-5.67), suggesting that there would be 2.84 relative excess risk due to the additive interaction; AP=0.48 (0.20-0.76), indicating that 48% of T2DM exposed to both risk factors was attributable to the additive interaction; and SI was 2.36 (1.15-4.87), suggesting that the risk of T2DM in obese smokers was 2.36 times as high as the sum of risks in the participants exposed to a single risk factor alone. We did not find a significant interaction between smoking and overall obesity on T2DM, but the incidence of T2DM in overall obese smokers was also highest. Both current smoking and abdominal obesity are strong risk factors of T2DM in the Chinese population. This study further demonstrates an additive interaction of current smoking and abdominal obesity on T2DM risk.

Aldosterone is not involved in the ventricular remodeling process induced by tobacco smoke exposure

BACKGROUND/AIMS

Renin-angiotensin-aldosterone system blockade with a mineralocorticoid-receptor antagonist has not yet been studied in exposure to tobacco smoke (TS) models. Thus, this study investigated the role of spironolactone on cardiac remodeling induced by exposure to tobacco smoke.

METHODS

Male Wistar rats were divided into 4 groups: a control group (group C, n=11); a group with 2 months of cigarette smoke exposure (group TS-C, n=13); a group that received spironolactone 20 mg/kg of diet/day and no cigarette smoke exposure (group TS-S, n=13); and a group with 2 months of cigarette smoke exposure and spironolactone supplementation (group S, n=12). The rats were observed for a period of 60 days, during which morphological, biochemical and functional analyses were performed.

RESULTS

There was no difference in invasive mean arterial pressure among the groups. There were no interactions between tobacco smoke exposure and spironolactone in the morphological and functional analysis. However, in the echocardiographic analysis, the TS groups had left chamber enlargement, higher left ventricular mass index and higher isovolumetric relaxation time corrected by heart rate compared with the non-TS groups. In vitro left ventricular diastolic function also worsened in the TS groups and was not influenced by spironolactone. In addition, there were no differences in myocardial levels of IFN-γ, TNF-α, IL-10, ICAM-1 and GLUT4 [TS: OR 0.52, 95%CI (-0.007; 0.11); Spironolactone: OR -0.01, 95%CI (-0.07;0.05)].

CONCLUSION

Our data do not support the participation of aldosterone in the ventricular remodeling process induced by exposed to cigarette smoke.

Association of cigarette smoking and tar and nicotine intake with development of type 2 diabetes mellitus in men and women from the general population: the MONICA/KORA Augsburg Cohort Study

AIMS/HYPOTHESIS

We examined sex-specific associations between cigarette smoking and incident type 2 diabetes mellitus in Germany.

SUBJECTS, MATERIALS AND METHODS

The study was based on 5,470 men and 5,422 women (aged 25-74 years) without diabetes who participated in one of the three population-based MONICA Augsburg surveys between 1984 and 1995. Incident cases of type 2 diabetes were assessed using follow-up questionnaires. Hazard ratios (HRs) were estimated from Cox proportional hazard models.

RESULTS

Up to 31 December 2002 a total of 409 cases of incident type 2 diabetes among men and 263 among women were registered. The number of cigarettes and the nicotine and tar consumption per day were associated with a significantly increased risk of type 2 diabetes among men, but not among women; this could be due to the low power of the study in women. After multivariable adjustment, the HRs for type 2 diabetes compared with never-smokers were 1.48, 2.03 and 2.10 for men smoking 1 to 14, 15 to 19 and > or =20 cigarettes/day (p for trend <0.0001) and 1.25, 1.34 and 1.37 for women smoking 1 to 9, 10 to 19 and > or =20 cigarettes/day (p for trend 0.0985). Compared with never-smokers, the HRs for increasing tar intake in men (1-167, 168-259 and > or =260 mg/day) were 1.45, 2.32 and 2.07 (p for trend <0.0001); the respective HRs in women (1-89, 90-194 and > or =195 mg/day) were 1.18, 1.57 and 1.24 (p for trend 0.1159).

CONCLUSIONS/INTERPRETATION

Cigarette smoking is an important modifiable risk factor of type 2 diabetes particularly in men from the general population.

Opposite effects of insulin-like molecules and leptin in coronary heart disease of type 2 diabetes Preliminary data

INTRODUCTION

Leptin and insulin have been reported to be risk factors for coronary heart disease (CHD) in the general population, but their role in type 2 diabetes still remains unclear.

MATERIALS AND METHODS

The role of leptin and insulin upon CHD in type 2 diabetes was assessed in 154 patients, aged 31-77 years, who were treated with oral anti-diabetic agents. Multivariate logistic regression analyses were used with CHD (an established history of CHD or an abnormal treadmill test) as dependent, and leptin, insulin and potential confounders as independent variables.

RESULTS

Endogenous insulin was significantly associated with CHD in a model controlling for gender, age, duration of diabetes, body mass index, smoking and leptin (Odds ratio 1.45 per decile, 95% confidence interval 1.11-1.90). Improving control for confounding by replacing body mass index by subcutaneous fat (CT-measured at the L4-L5 level) and height in this model, resulted in a significant negative association between leptin and CHD (OR 0.60, 95% CI 0.37-0.96).

DISCUSSION

Leptin might have a beneficial effect on CHD in type 2 diabetes, probably by counteracting the effect of insulin-like molecules or insulin resistance. The effect was elucidated only after careful control for confounding by subcutaneous fat, the main source of leptin production.

Inhibitory effects of cigarette smoke on glial inducible nitric oxide synthase and lack of protective properties against oxidative neurotoxins in vitro

Epidemiological studies consistently report an inverse correlation between cigarette smoking and associated risk for Parkinson's disease (PD). The degeneration of dopaminergic neurons may involve the toxic metabolic products of glial cell monoamine oxidase (MAO) and inducible nitric oxide synthase (iNOS). This study evaluates the direct protective effects of cigarette smoke (CS) against potential neurotoxic products of MAO, such as 1-methyl-4-phenylpyridinium (MPP+), 6-hydroxydopamine (6-OHDA) and hydrogen peroxide (H2O2) in brain neuroblastoma. Moreover, the effects of CS were also evaluated on endotoxin/cytokine activated glioma iNOS protein expression and MAO enzyme activity. Cigarette smoke condensates (CSCs) were acquired from Marlboro 20 Class A and Kentucky 2R4F reference research (2R4F) cigarettes. The CSCs did not protect against 6-OHDA or H2O2 toxicity in neuroblastoma, and exhibited a very mild protective effect [approximately 10%] against MPP+. Neither CSC demonstrated antioxidant capability, but conversely contained high concentration of NO2-. Paradoxically, in glioma cells, iNOS protein expression and endogenous enzymatic NO2- production were significantly blocked by both CSCs. Both CSCs also inhibited glioma MAO-A and MAO-B [1.4.3.4]. Kinetic analysis indicated that 2R4F-CSC displayed competitive inhibition and the Marlboro-CSC exerted potent competitive and non-competitive inhibition. In conclusion, these data suggest that cigarette smoke does not appear to directly protect against the toxicity of the selected neurotoxins. In contrast, CS exerts pronounced effects on glia, whereby its presence can simultaneously attenuate cytokine induction of iNOS and MAO.

Influence of smoking and snus on the prevalence and incidence of type 2 diabetes amongst men: the northern Sweden MONICA study

OBJECTIVE

To explore the effect of smoking and smokeless tobacco, 'snus', on the risk of type 2 diabetes.

DESIGN

Population-based cross-sectional and prospective follow-up study in northern Sweden.

SUBJECTS

A total of 3384 men, aged 25-74 years, who participated in the MONICA study in 1986, 1990, 1994 or 1999, 1170 of whom had an oral glucose tolerance test. In 1999, 1757 men from previous cohorts returned for re-examination. Main outcome measures. We compared the prevalence of type 2 diabetes or pathological glucose tolerance (PGT) amongst tobacco users to that of nonusers at entry into the study and at follow-up, using odds ratios.

RESULTS

Compared with never users, the age-adjusted risk of prevalent clinically diagnosed diabetes for ever smokers was 1.88 (CI 1.17-3.0) and for smokers 1.74 (0.94-3.2). Corresponding odds ratios for snus users were 1.34 (0.65-2.7) and 1.18 (0.48-2.9). We found no increased risk of prevalent PGT in snus users or smokers. Former smokers and snus users had an insignificantly increased risk for PGT. Compared with nonusers, the age-adjusted risk of developing clinically diagnosed diabetes during follow-up was 4.63 (1.37-16) in consistent exclusive smokers, 3.20 (1.16-8.8) in ex-smokers and no cases in consistent snus users. The risk of PGT during follow-up was not increased in consistent tobacco users but evident, although not statistically significant, in those who quit snus during the follow-up period, 1.85 (0.60-5.7). Adjustment for physical activity and alcohol consumption did not change the major findings.

CONCLUSIONS

The risk of diabetes for snus users was not significantly increased. Smoking was associated with prevalent and incident cases of diabetes. Ex-tobacco users tended towards more PGT.

Inter-relationships between lifestyle and diabetes mellitus, overweight/obesity and hypertension in Nigeria

This study of inter-relationship between life styles and diabetes mellitus, overweight/obesity and hypertension was carried out to determine the life styles of the bank workers and the nutritional related diseases. A total sample of 570 was systematically drawn from workers of the United Bank for Africa Plc in Lagos for this study, with the following results. Not surprisingly the level of education influenced life style (P<0.05). There was also a statistically significant relationship between life style and the consumption of alcohol and diabetes, but no relationship was found between smoking and diabetes. There was a significant correlation with their consumption of fatty foods and vegetables. A relationship between increased protein intake and an increase in educational status (P<0.05) was found. There was association between obesity and hypertension (P<0.05), and between increase in frequency of clinic visitation and hypertension which was statistically significant (Chi square P<.05).

Cigarette smoking and diabetes mellitus: evidence of a positive association from a large prospective cohort study

OBJECTIVE

Only a few prospective studies have examined the relationship between the frequency of cigarette smoking and the incidence of diabetes mellitus. The purpose of this study was to determine whether greater frequency of cigarette smoking accelerated the development of diabetes mellitus, and whether quitting reversed the effect.

METHODS

Data were collected in the Cancer Prevention Study I, a prospective cohort study conducted from 1959 through 1972 by the American Cancer Society where volunteers recruited more than one million acquaintances in 25 US states. From these over one million original participants, 275,190 men and 434,637 women aged > or = 30 years were selected for the primary analysis using predetermined criteria.

RESULTS

As smoking increased, the rate of diabetes increased for both men and women. Among those who smoked > or = 2 packs per day at baseline, men had a 45% higher diabetes rate than men who had never smoked; the comparable increase for women was 74%. Quitting smoking reduced the rate of diabetes to that of non-smokers after 5 years in women and after 10 years in men.

CONCLUSIONS

A dose-response relationship seems likely between smoking and incidence of diabetes. Smokers who quit may derive substantial benefit from doing so. Confirmation of these observations is needed through additional epidemiological and biological research.