Association of oral microbiome with type 2 diabetes risk.

BACKGROUND AND OBJECTIVE: The oral microbiome may help to maintain systemic health, including how it affects blood glucose levels; however, direct evidence linking the oral microbiome with diabetes is lacking. MATERIAL AND METHODS: We compared the oral microbiome profiles of 98 participants with incident diabetes, 99 obese non-diabetics and 97 normal weight non-diabetics, via deep sequencing of the 16S rRNA gene. RESULTS: We found that the phylum Actinobacteria was present significantly less abundant among patients with diabetes than among the controls (p = 3.9 × 10-3 ); the odds ratio (OR) and 95% confidence interval (CI) was 0.27 (0.11-0.66) for those individuals who had relative abundance higher than the median value. Within this phylum, five families and seven genera were observed, and most of them were less abundant among patients with diabetes. Notably, genera Actinomyces and Atopobium were associated with 66% and 72% decreased risk of diabetes with p-values of 8.9 × 10-3 and 7.4 × 10-3 , respectively. Stratified analyses by race showed that most taxa in this phylum were associated with diabetes in both black and white participants. This phylum was also less abundant among non-diabetic obese subjects compared to normal weight individuals, particularly genera Mobiluncus, Corynebacterium and Bifidobacterium, which showed p < 0.05. CONCLUSION: Our study revealed that multiple bacteria taxa in the phylum Actinobacteria are associated with the risk of type 2 diabetes. Some are also associated with the prevalence of obesity, suggesting that the oral microbiome may play an important role in diabetes etiology.

Oral health and risk of colorectal cancer: results from three cohort studies and a meta-analysis.

BACKGROUND: While studies have shown that poor oral health status may increase the risk of cancer, evidence of a specific association with the risk of colorectal cancer (CRC) is inconclusive. We evaluated the association between oral health and CRC risk using data from three large cohorts: the Shanghai Men's Health Study (SMHS), the Shanghai Women's Health Study (SWHS), and the Southern Community Cohort Study (SCCS), and carried out a meta-analysis of results from other relevant published studies. PATIENTS AND METHODS: This study applied a nested case-control study design and included 825 cases/3298 controls from the SMHS/SWHS and 238 cases/2258 controls from the SCCS. The association between oral health status (i.e. tooth loss/tooth decay) and CRC risk was assessed using conditional logistic regression models. A meta-analysis was carried out based on results from the present study and three published studies. RESULTS: We found that tooth loss was not associated with increased risk of CRC. ORs and respective 95% CIs associated with loss of 1-5, 6-10, and >10 teeth compared with those with full teeth are 0.87 (0.69-1.10), 0.93 (0.70-1.24), and 0.85 (0.66-1.11) among SMHS/SWHS participants; and 1.13 (0.72-1.79), 0.87 (0.52-1.43), and 1.00 (0.63-1.58) for those with loss of 1-4, 5-10, and >10 teeth among SCCS participants. Data regarding tooth decay were available in the SCCS, but were not associated with CRC risk. Meta-analysis confirmed the null association between tooth loss/periodontal disease and CRC risk (OR 1.05, 95% CI 0.86-1.29). CONCLUSION: In this analysis of three cohorts and a meta-analysis, we found no evidence supporting an association between oral health and CRC risk.

Compensatory regulation of HDAC5 in muscle maintains metabolic adaptive responses and metabolism in response to energetic stress.

Some gene deletions or mutations have little effect on metabolism and metabolic adaptation because of redundancy and/or compensation in metabolic pathways. The mechanisms for redundancy and/or compensation in metabolic adaptation in mammalian cells are unidentified. Here, we show that in mouse muscle and myogenic cells, compensatory regulation of the histone deacetylase (HDAC5) transcriptional repressor maintains metabolic integrity. HDAC5 phosphorylation regulated the expression of diverse metabolic genes and glucose metabolism in mouse C2C12 myogenic cells. However, loss of AMP-activated protein kinase (AMPK), a HDAC5 kinase, in muscle did not affect HDAC5 phosphorylation in mouse skeletal muscle during exercise, but resulted in a compensatory increase (32.6%) in the activation of protein kinase D (PKD), an alternate HDAC5 kinase. Constitutive PKD activation in mouse C2C12 myogenic cells regulated metabolic genes and glucose metabolism. Although aspects of this response were HDAC5 phosphorylation dependent, blocking HDAC5 phosphorylation when PKD was active engaged an alternative compensatory adaptive mechanism, which involved post-transcriptional reductions in HDAC5 mRNA (-93.1%) and protein. This enhanced the expression of a specific subset of metabolic genes and mitochondrial metabolism. These data show that compensatory regulation of HDAC5 maintains metabolic integrity in mammalian cells and reinforces the importance of preserving the cellular metabolic adaptive response.

Exercise, muscle, and CHO metabolism.

Carbohydrates (CHO) are a key source of energy for contracting skeletal muscle during strenuous exercise and fatigue during such exercise often coincides with CHO depletion. Our current understanding of the importance of CHO for exercise metabolism has its foundations in classic studies in the early 20th century by Scandinavian physiologists and Bengt Saltin contributed significantly to that tradition. This brief review summarizes our contemporary understanding of key aspects of muscle glycogen and glucose metabolism during exercise, through the lens of seminal studies by Bengt Saltin.

Heterogeneity of clinical and environmental isolates of Mycobacterium fortuitum using repetitive element sequence-based PCR: municipal water an unlikely source of community-acquired infections.

M. fortuitum is a rapidly growing mycobacterium associated with community-acquired and nosocomial wound, soft tissue, and pulmonary infections. It has been postulated that water has been the source of infection especially in the hospital setting. The aim of this study was to determine if municipal water may be the source of community-acquired or nosocomial infections in the Brisbane area. Between 2007 and 2009, 20 strains of M. fortuitum were recovered from municipal water and 53 patients' isolates were submitted to the reference laboratory. A wide variation in strain types was identified using repetitive element sequence-based PCR, with 13 clusters of ⩾2 indistinguishable isolates, and 28 patterns consisting of individual isolates. The clusters could be grouped into seven similar groups (>95% similarity). Municipal water and clinical isolates collected during the same time period and from the same geographical area consisted of different strain types, making municipal water an unlikely source of sporadic human infection.

Exercise increases skeletal muscle GLUT4 gene expression in patients with type 2 diabetes.

The aim of the study was to determine the effect of a single bout of exercise on GLUT4 gene expression in muscle of patients with type 2 diabetes (T2D) and control subjects, matched for age and body mass index. Nine patients with T2D and nine control subjects performed 60 min of cycling exercise at ~55% peak power (W(max) ). Skeletal muscle biopsies were obtained at baseline, immediately post and 3-h post exercise. GLUT4 mRNA expression increased (p < 0.05) to a similar extent immediately post exercise in control (~60%) and T2D (~66%) subjects, and remained elevated (p < 0.05) 3-h post exercise with no differences between groups. Similarly, p-AMP-activated protein kinase, p38 mitogen-activated kinase and proliferator-activated receptor gamma co-activator-alpha mRNA expression were increased (p < 0.05) post exercise, and were not different between the groups. In conclusion, a single bout of exercise increased skeletal muscle GLUT4 mRNA expression in patients with T2D to a similar extent as in control subjects.

Genotyping of Enterococcus faecalis and Enterococcus faecium isolates by use of a set of eight single nucleotide polymorphisms.

A single nucleotide polymorphism (SNP) genotyping method for Enterococcus faecalis and Enterococcus faecium was developed using the "Minimum SNPs" program. SNP sets were interrogated using allele-specific real-time PCR. SNP typing subdivided clonal complexes 2 and 9 of E. faecalis and 17 of E. faecium, members of which cause the majority of nosocomial infections globally.

Exercise training increases adipose tissue GLUT4 expression in patients with type 2 diabetes.

We investigated the effects of exercise training on adipose tissue and skeletal muscle GLUT4 expression in patients with type 2 diabetes (T2D). Muscle and adipose tissue samples were obtained before and after 4-weeks of exercise training in seven patients with T2D [47 ± 2 years, body mass index (BMI) 28 ± 2]. Seven control subjects (54 ± 4, BMI 30 ± 2) were recruited for baseline comparison. Adipose tissue GLUT4 protein expression was 43% lower (p < 0.05) in patients with T2D compared with control subjects and exercise training increased (p < 0.05) adipose tissue GLUT4 expression by 36%. Skeletal muscle GLUT4 protein expression was not different between control subjects and patients with T2D. Exercise training increased (p < 0.05) skeletal muscle GLUT4 protein expression by 20%. In conclusion, 4-weeks of exercise training increased GLUT4 expression in adipose tissue and skeletal muscle of patients with T2D, although the functional benefits of this adaptation appear to be dependent on an optimal ß-cell function.

Cough-generated aerosols of Pseudomonas aeruginosa and other Gram-negative bacteria from patients with cystic fibrosis.

BACKGROUND: Pseudomonas aeruginosa is the most common bacterial pathogen in patients with cystic fibrosis (CF). Current infection control guidelines aim to prevent transmission via contact and respiratory droplet routes and do not consider the possibility of airborne transmission. It was hypothesised that subjects with CF produce viable respirable bacterial aerosols with coughing. METHODS: A cross-sectional study was undertaken of 15 children and 13 adults with CF, 26 chronically infected with P aeruginosa. A cough aerosol sampling system enabled fractioning of respiratory particles of different sizes and culture of viable Gram-negative non-fermentative bacteria. Cough aerosols were collected during 5 min of voluntary coughing and during a sputum induction procedure when tolerated. Standardised quantitative culture and genotyping techniques were used. RESULTS: P aeruginosa was isolated in cough aerosols of 25 subjects (89%), 22 of whom produced sputum samples. P aeruginosa from sputum and paired cough aerosols were indistinguishable by molecular typing. In four cases the same genotype was isolated from ambient room air. Approximately 70% of viable aerosols collected during voluntary coughing were of particles

A nested real-time PCR assay has an increased sensitivity suitable for detection of viruses in aerosol studies.

AIMS: Influenza is commonly spread by infectious aerosols; however, detection of viruses in aerosols is not sensitive enough to confirm the characteristics of virus aerosols. The aim of this study was to develop an assay for respiratory viruses sufficiently sensitive to be used in epidemiological studies. METHOD: A two-step, nested real-time PCR assay was developed for MS2 bacteriophage, and for influenza A and B, parainfluenza 1 and human respiratory syncytial virus. Outer primer pairs were designed to nest each existing real-time PCR assay. The sensitivities of the nested real-time PCR assays were compared to those of existing real-time PCR assays. Both assays were applied in an aerosol study to compare their detection limits in air samples. CONCLUSIONS: The nested real-time PCR assays were found to be several logs more sensitive than the real-time PCR assays, with lower levels of virus detected at lower Ct values. The nested real-time PCR assay successfully detected MS2 in air samples, whereas the real-time assay did not. SIGNIFICANCE AND IMPACT OF THE STUDY: The sensitive assays for respiratory viruses will permit further research using air samples from naturally generated virus aerosols. This will inform current knowledge regarding the risks associated with the spread of viruses through aerosol transmission.

Characterization of expiration air jets and droplet size distributions immediately at the mouth opening.

Size distributions of expiratory droplets expelled during coughing and speaking and the velocities of the expiration air jets of healthy volunteers were measured. Droplet size was measured using the interferometric Mie imaging (IMI) technique while the particle image velocimetry (PIV) technique was used for measuring air velocity. These techniques allowed measurements in close proximity to the mouth and avoided air sampling losses. The average expiration air velocity was 11.7 m/s for coughing and 3.9 m/s for speaking. Under the experimental setting, evaporation and condensation effects had negligible impact on the measured droplet size. The geometric mean diameter of droplets from coughing was 13.5 µm and it was 16.0 µm for speaking (counting 1-100). The estimated total number of droplets expelled ranged from 947 to 2085 per cough and 112-6720 for speaking. The estimated droplet concentrations for coughing ranged from 2.4 to 5.2 cm-3 per cough and 0.004-0.223 cm-3 for speaking.

Population similarity analysis of indicator bacteria for source prediction of faecal pollution in a coastal lake.

Biochemical fingerprinting (BF) databases of 524 enterococci and 571 Escherichia coli isolates and an antibiotic resistance analysis (ARA) database comprising of 380 E. coli isolates from four suspected sources (i.e. dogs, chickens, waterfowls, and human sewage) were developed to predict the sources of faecal pollution in a recreational coastal lake. Twenty water samples representing four sampling episodes were collected from five sites and the enterococci and E. coli population from each site were compared with those of the databases. The degree of similarity between bacterial populations was measured as population similarity (Sp) coefficient. Using the BF-database, bacterial populations of waterfowls showed the highest similarity with the water samples followed by a sewage treatment plant (STP). Higher population similarities were found between samples from STP and water samples especially at two sites (T2 and T3) which were located near the sewerage pipes collecting wastewater from the study area. When using the ARA-database, the highest similarity was found between E. coli populations from STP and water samples at sites T2 and T4. Both faecal indicators and as well as methods predicted human faecal pollution, possibly through leakage from submerged sewerage pipes. The results indicated that the Sp-analysis of faecal indicator bacterial populations from suspected sources and water samples can be used as a simple tool to predict the source(s) of faecal pollution in surface waters.

Body mass index and health-related quality of life.

OBJECTIVE: There are conflicting data regarding the association between body mass index (BMI) and health-related quality of life (HRQoL), especially among certain population subgroups and for mental and physical health domains. METHODS: This study analysed the relationship between BMI and HRQoL (Patient-Reported Outcomes Measurement Information System mental and physical health scales) using ordinary least squares regression. Each model allowed for the possibility of a non-linear relationship between BMI and the outcome, adjusting for age, gender, comorbidities, diet and physical activity. RESULTS: A total of 10,133 respondents were predominantly female (71.7%), White (84.1%), median age of 52.1 years (interquartile range 37.2-63.3) and median BMI of 27.9 (interquartile range 24.0-33.2). In adjusted models, BMI was significantly associated with physical and mental HRQoL (p < 0.001). For physical HRQoL, there was a significant interaction with age (p = 0.02). For mental HRQoL, there was a significant interaction with sex (p = 0.0004) but not age (p = 0.7). CONCLUSIONS: This study demonstrates a non-linear association of variable clinical relevance between BMI and HRQoL after adjusting for demographic factors and comorbidities. The relationship between BMI and HRQoL is nuanced and impacted by gender and age. These findings challenge the idea of obesity as a main driver of reduced HRQoL, particularly among women and with respect to mental HRQoL.

Reduced fetal vitamin D status by maternal undernutrition during discrete gestational windows in sheep.

Placental transport of vitamin D and other nutrients (e.g. amino acids, fats and glucose) to the fetus is sensitive to maternal and fetal nutritional cues. We studied the effect of maternal calorific restriction on fetal vitamin D status and the placental expression of genes for nutrient transport [aromatic T-type amino acid transporter-1 (TAT-1); triglyceride hydrolase/lipoprotein uptake facilitator lipoprotein lipase (LPL)] and vitamin D homeostasis [CYP27B1; vitamin D receptor (VDR)], and their association with markers of fetal cardiovascular function and skeletal muscle growth. Pregnant sheep received 100% total metabolizable energy (ME) requirements (control), 40% total ME requirements peri-implantation [PI40, 1-31 days of gestation (dGA)] or 50% total ME requirements in late gestation (L, 104-127 dGA). Fetal, but not maternal, plasma 25-hydroxy-vitamin D (25OHD) concentration was lower in PI40 and L maternal undernutrition groups (P<0.01) compared with the control group at 0.86 gestation. PI40 group placental CYP27B1 messenger RNA (mRNA) levels were increased (P<0.05) compared with the control group. Across all groups, higher fetal plasma 25OHD concentration was associated with higher skeletal muscle myofibre and capillary density (P<0.05). In the placenta, higher VDR mRNA levels were associated with higher TAT-1 (P<0.05) and LPL (P<0.01) mRNA levels. In the PI40 maternal undernutrition group only, reduced fetal plasma 25OHD concentration may be mediated in part by altered placental CYP27B1. The association between placental mRNA levels of VDR and nutrient transport genes suggests a way in which the placenta may integrate nutritional cues in the face of maternal dietary challenges and alter fetal physiology.

Fiber type-specific expression of GLUT4 in human skeletal muscle: influence of exercise training.

The fiber type-specific expression of skeletal muscle GLUT4 and the effect of 2 weeks of low-intensity training were investigated in 8 young untrained male subjects. Single muscle fibers were dissected from a vastus lateralis biopsy sample. Based on myosin heavy chain (MHC) expression, fibers were pooled into 3 groups (MHC I, MHC IIA, and MHC IIX), and the GLUT4 content of 15-40 pooled fibers was determined using SDS-PAGE and immunological detection. The GLUT4 content in pooled muscle fibers expressing MHC I was approximately 20% higher (P < 0.05) than that in muscle fibers expressing MHC IIA or MHC IIX. No difference in GLUT4 could be detected between fibers expressing MHC IIA or MHC IIX. Two weeks of exercise training increased (P < 0.05) the peak power output of the knee extensors by 13%, the maximal activities of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase by 21 and 18%, respectively, and the GLUT4 protein content by 26% in a muscle homogenate. Furthermore, a 23% increase (P < 0.05) in GLUT4 was seen in fibers expressing the MHC I isoform after exercise training for 2 weeks. No change was seen in fibers expressing MHC IIA or MHC IIX. In conclusion, our data directly demonstrate that GLUT4 is expressed in a fiber type-specific manner in human skeletal muscle, although fiber type differences are relatively small. In addition, low-intensity exercise training recruiting primarily fibers expressing MHC I increased GLUT4 content in these fibers but not in fibers expressing MHC IIA or MHC IIX, indicating that GLUT4 protein content is related more to activity level of the fiber than to its fiber type, which is defined by expression of contractile protein.

A method for measuring sarcoplasmic reticulum calcium uptake in the skeletal muscle using Fura-2.

We have presented an assay for measuring the rate of sarcoplasmic reticulum (SR) Ca2+ uptake and Ca2+ release in skeletal muscle homogenates using the fluorescent Ca2+ probe Fura-2. Using this assay, we investigated the effects of an elevated temperature (40 degrees C) and lowered pH (6.8), two factors proposed to be involved in skeletal muscle fatigue, on SR Ca2+ uptake. The EDL muscle was found to have a higher rate of Ca2+ uptake than the soleus (34%). Exposure of the muscles to a raised temperature, but not a reduced pH, resulted in a reduction in the rate of Ca2+ uptake in both the EDL and soleus homogenates. This uptake process was blocked by cyclopiazonic acid (CPA) a specific inhibitor of the major transport protein of the sarcoplasmic reticulum, the Ca(2+)-ATPase. Calcium release was induced using AgNO3 after loading of the vesicles during the uptake process. It was found that AgNO3 was only effective in producing Ca2+ release in the EDL muscles. The soleus muscles did not release Ca2+ under varying [Mg2+] or with Hg2+ substitution for Ag+, suggesting that fast- and slow-twitch muscle fibres require different conditions for maximum Ca2+ release, or that different isoforms of the Ca2+ release channels are present in the different fibres.

Cardioselectivity of prenalterol and isoproterenol.

We examined the hemodynamic effects and kinetics of prenalterol, a new beta-adrenoceptor agonist, in 10 normal subjects. There is some doubt whether prenalterol is selective for beta 1 adrenoceptors in animals; therefore, we also compared its cardioselectivity with that of the nonselective agonist, isoproterenol, with respect to heart rate (HR) and blood pressure (BP) responses after inhibition of cardiovascular reflexes with atropine, clonidine, and phentolamine. After intravenous (2.5 mg) and oral (10 mg and 100 mg) dosing, t 1/2 beta was 2 to 3 hr. Oral bioavailability averaged 33% and was independent of dose. Oral prenalterol, 10 mg and 100 mg, increased resting HR, systolic BP, and cardiac index by up to 27% but had no significant effects during graded exercise. Prenalterol infusions were calculated to attain steady-state plasma concentrations of 10, 20, and 40 ng/ml. HR and BP effects of the levels (10.8, 23.6, and 47.4 ng/ml) were compared with those of 0.5, 1.5, and 2.5 micrograms isoproterenol. Before autonomic block, prenalterol increased HR by 10 bpm at the highest dose and mean arterial pressure (MAP) by 10 mm Hg. In contrast, HR rose and MAP fell after isoproterenol. After block, at the highest doses of prenalterol and isoproterenol, there was an average rise in HR of 42 and 27 bpm; BP was almost maintained after the former but fell by 33 mm Hg after the latter. Prenalterol is an inotropic drug that has the effects of a full cardioselective beta-adrenoceptor agonist. Its inotropic effects are evident at doses that have little effect on HR because of the modifying effect of cardiovascular reflexes. The hemodynamic effects are most obvious at rest when sympathetic tone is low.

Muscle glycogen storage after prolonged exercise: effect of the frequency of carbohydrate feedings.

We reported previously that intake of carbohydrate foods with a high glycemic index (GI) produced greater glycogen storage and greater postprandial glucose and insulin responses during 24 h of postexercise recovery than did intake of low-GI carbohydrate foods. In the present study we examined the importance of the greater incremental glucose and insulin concentrations on glycogen repletion by comparing intake of large carbohydrate meals ("gorging") with a pattern of frequent, small, carbohydrate snacks ("nibbling"), which simulates the flattened glucose and insulin responses after low-GI carbohydrate meals. Eight well-trained triathletes [x +/- SEM: 25.6 +/- 1.5 y of age, weighing 70.2 +/- 1.9 kg, and with a maximal oxygen uptake (VO2max) of 4.2 +/- 0.2 L/min] undertook an exercise trial (2 h at 75% VO2max followed by four 30-s sprints) to deplete muscle glycogen on two occasions, 1 wk apart For 24 h after each trial, subjects rested and consumed the same diet composed exclusively of high-GI carbohydrate foods, providing 10 g carbohydrate/kg body mass. The "gorging" trial provided the food as four large meals of equal carbohydrate content eaten at 0, 4, 8, and 20 h of recovery, whereas in the "nibbling" trial each of the meals was divided into four snacks and fed at hourly intervals (0-11, 20-23 h). However, there was no significant difference in muscle glycogen storage between the two groups over the 24 h (gorging: 74.1 +/- 8.0 mmol/kg wet wt; nibbling: 94.5 +/- 14.6 mmol/kg wet wt). The results of this study suggest that there is no difference in postexercise glycogen storage over 24 h when a high-carbohydrate diet is fed as small frequent snacks or as large meals, and that a mechanism other than lowered blood glucose and insulin concentrations needs to be sought to explain the reduced rate of glycogen storage after consumption of low-GI carbohydrate foods.

Exercise increases serum Hsp72 in humans.

Recent evidence suggests that heat shock proteins (Hsps) may have an important systemic role as a signal to activate the immune system. Since acute exercise is known to induce Hsp72 (the inducible form of the 70-kDa family of Hsp) in a variety of tissues including contracting skeletal muscle, we hypothesized that such exercise would result in the release of Hsp72 from stressed cells into the blood. Six humans (5 males, 1 female) ran on a treadmill for 60 minutes at a workload corresponding to 70% of their peak oxygen consumption. Blood was sampled from a forearm vein at rest (R), 30 minutes during exercise, immediately postexercise (60 minutes), and 2, 8, and 24 hours after exercise. These samples were analyzed for serum Hsp72 protein. In addition, plasma creatine kinase (CK) was measured at these time points as a crude marker of muscle damage. With the exception of the sample collected at 30 minutes, muscle biopsies (n = 5 males) were also obtained from the vastus lateralis at the time of blood sampling and analyzed for Hsp72 gene and protein expression. Serum Hsp72 protein increased from rest, both during and after exercise (0.13 0.10 vs 0.87+/-0.24 and 1.02+/-0.41 ng/mL at rest, 30 and 60 minutes, respectively, P < 0.05, mean SE). In addition, plasma CK was elevated (P < 0.05) 8 hours postexercise. Skeletal muscle Hsp72 mRNA expression increased 6.5-fold (P < 0.05) from rest 2 hours postexercise, and although there was a tendency for Hsp72 protein expression to be elevated 2 and 8 hours following exercise compared with rest, results were not statistically significant. The increase in serum Hsp72 preceded any increase in Hsp72 gene or protein expression in contracting muscle, suggesting that Hsp72 was released from other tissues or organs. This study is the first to demonstrate that acute exercise can increase Hsp72 in the peripheral circulation, suggesting that during stress these proteins may indeed have a systemic role.