Genome-wide association analysis identifies loci for type 2 diabetes and triglyceride levels

New strategies for prevention and treatment of type 2 diabetes (T2D) require improved insight into disease etiology. We analyzed 386,731 common single-nucleotide polymorphisms (SNPs) in 1464 patients with T2D and 1467 matched controls, each characterized for measures of glucose metabolism, lipids, obesity, and blood pressure. With collaborators (FUSION and WTCCC/UKT2D), we identified and confirmed three loci associated with T2D-in a noncoding region near CDKN2A and CDKN2B, in an intron of IGF2BP2, and an intron of CDKAL1-and replicated associations near HHEX and in SLC30A8 found by a recent whole-genome association study. We identified and confirmed association of a SNP in an intron of glucokinase regulatory protein (GCKR) with serum triglycerides. The discovery of associated variants in unsuspected genes and outside coding regions illustrates the ability of genome-wide association studies to provide potentially important clues to the pathogenesis of common diseases.

Fat cell enlargement is an independent marker of insulin resistance and 'hyperleptinaemia'

AIMS/HYPOTHESIS

The aim of this study was to explore whether fat cell size in human subcutaneous and omental adipose tissue is independently related to insulin action and adipokine levels.

MATERIALS AND METHODS

Fat cells were prepared from abdominal subcutaneous biopsies obtained from 49 type 2 diabetic and 83 non-diabetic subjects and from omental biopsies obtained from 37 non-diabetic subjects. Cell size and insulin action on glucose uptake capacity in vitro were assessed in isolated fat cells. Insulin sensitivity in vivo was assessed with euglycaemic-hyperinsulinaemic clamps. Fasting blood samples were collected and adipokines and NEFA were measured.

RESULTS

Negative correlations were found between subcutaneous fat cell size and insulin sensitivity assessed as M-value during clamp and as insulin action on glucose uptake in fat cells in vitro. This was seen in non-diabetic subjects after including age, sex and BMI in the analyses. No such relationship was found in type 2 diabetic subjects. In both groups, subcutaneous fat cell size correlated positively and independently with plasma levels of leptin but not to any of the other assessed adipokines. In non-diabetic subjects, omental fat cell size was independently and negatively correlated with insulin action in subcutaneous, but not omental, fat cells in vitro.

CONCLUSIONS/INTERPRETATION

Fat cell enlargement is associated with insulin resistance in non-diabetic individuals independently of BMI. This was not seen in type 2 diabetic subjects, suggesting that after development of type 2 diabetes other factors, not related to fat cell size, become more important for the modulation of insulin resistance.

Altered nucleotide sugar metabolism in Streptococcus thermophilus interferes with nitrogen metabolism

Exopolysaccharide (EPS)-producing Streptococcus thermophilus strains have attracted interest recently, since the EPSs act as natural viscosifiers and texture enhancers of fermented foods. We have previously reported that the low level of EPS production by S. thermophilus LY03 could be improved by altering the activities of enzymes in the central carbon metabolism involved in the nucleotide sugar metabolism. In this study, we observed a reduced growth in milk for the strains with increased UDP-glucose pyrophosphorylase (GalU) activity together with either enhanced phosphoglucomutase activity, and/or enhanced activity of the Leloir enzymes. Rapid growth of these mutants in milk could be restored by the addition of four specific amino acids, i.e. Glu, His, Met, and Val. This amino acid requirement was confirmed in a defined medium. Furthermore, the 31P NMR spectra showed higher levels of the GalU reactants pyrophosphate (PPi) and UDP-glucose in the engineered strain, TMB 6013, compared to the parent strain, LY03. These products plus Glu and the GalU reactant UTP are known to be involved in the nitrogen regulatory system in many bacteria. Thus, these results suggest that the reaction catalyzed by GalU is connected to the nitrogen demand of these engineered strains.

Snoring and daytime sleepiness as risk factors for hypertension and diabetes in women--a population-based study

The aim of this study was to analyze whether snoring and excessive daytime sleepiness (EDS), the main symptoms of obstructive sleep apnea syndrome (OSAS), are associated with hypertension and diabetes in women. A random sample of 6779 women aged 20-99 years answered questionnaires on sleep disturbances, daytime symptoms and somatic diseases. The women were categorized into four groups: "no EDS or snoring" (reference group), "snoring but no EDS", "EDS but no snoring" and "snoring and EDS". Prevalences of hypertension and diabetes were lowest in the reference group (8.7% and 1.6%, respectively) and highest among women with both snoring and EDS (hypertension: 26.3%, diabetes: 5.8%). In a multivariate model adjusting for age, body mass index, smoking, physical activity and alcohol dependency, "snoring and EDS" was a risk factor for hypertension (adjusted OR 1.82 (95% CI 1.30-2.55)) while isolated snoring or EDS was not. "Snoring and EDS" was more closely related to hypertension among women aged <50 years (adj. OR 3.41 (1.78-6.54) vs. 1.50 (1.02-2.19), P=0.01). For diabetes, both "EDS but no snoring" and "snoring and EDS" were risk factors and the associations were most pronounced in women aged >50 years (adj. OR 2.33 (1.28-4.26) for "EDS but no snoring" and 2.00 (1.05-3.84) for "snoring and EDS"). We conclude that the combination of snoring and EDS is a risk factor for hypertension and diabetes in women. For hypertension, the risk is partly age dependent and, for diabetes, EDS without snoring is a risk factor of similar magnitude. These differences might indicate differences in pathophysiologic mechanisms underlying the association between sleep-disordered breathing and hypertension and diabetes respectively.

Can anatomical and functional features in the upper airways predict sleep apnea? A population-based study in females

CONCLUSION

The importance of clinical findings in the nose and throat, including fiberoptic endoscopy during the Muller maneuver, in predicting sleep apnea is greater in normal-weight than in overweight women.

OBJECTIVES

The aim of this study was to identify clinical features that could predict sleep apnea in women.

METHOD

From 6817 women who previously answered a questionnaire concerning snoring habits, 230 women who reported habitual snoring and 170 women from the whole cohort went through a full-night polysomnography. A nose and throat examination including fiber endoscopic evaluation of the upper airways during the Muller maneuver was performed in a random selection of 132 women aged 20-70 years.

RESULTS

Sleep apnea was defined as an apnea-hypopnea index of > or = 10. The influence of clinical features on the prevalence of sleep apnea varied between normal-weight and overweight women. A low soft palate, retrognathia, the uvula touching the posterior pharyngeal wall in the supine position, and a 75% or more collapse at the soft palate during the Muller maneuver were all significant predictors of sleep apnea in women with a body mass index (BMI) < 25 kg/m2 but not in overweight women.

Risk Factors Associated With Snoring in Women With Special Emphasis on Body Mass Index

STUDY OBJECTIVES

Habitual snoring may be regarded as an indicator of sleep-disordered breathing, and the health consequences of sleep-disordered breathing are well-known. The aim of this study was to analyze the risk factors associated with habitual snoring in a large sample of women, with special emphasis on the determinants of snoring in women with different body mass index (BMI) levels.

DESIGN AND SETTING

A cross-sectional, epidemiologic, population-based study was performed by using a postal questionnaire that was sent to a randomly selected sample of 6,817 women >/= 20 years of age in Uppsala, Sweden.

RESULTS

The total prevalence of self-reported habitual snoring was 7.6%. There was a clear age dependence, with the highest prevalence of habitual snoring (14%) occurring between the ages of 50 and 59 years. Self-reported habitual snoring was related to BMI, neck circumference, and smoking >/= 10 cigarettes a day, after adjusting for possible confounders. When analyzing the influence of different risk factors in separate BMI groups, the results varied among the groups. The influence of alcohol dependence on snoring frequency was only significant in women with a BMI of < 20 kg/m(2), while physical inactivity was only associated with habitual snoring in women with a BMI of >/= 30 kg/m(2).

CONCLUSIONS

The prevalence of self-reported habitual snoring in women was strongly dependent on age and BMI. The importance of other risk factors differed depending on BMI, with alcohol dependence being associated with self-reported snoring in lean women, whereas physical inactivity was a risk factor for self-reported snoring in women with a high BMI.

Metabolically improved exopolysaccharide production by Streptococcus thermophilus and its influence on the rheological properties of fermented milk

Altered levels of enzymes in the central carbon metabolism in Streptococcus thermophilus increased the exopolysaccharide (EPS) production 3.3 times over that of the parent strain. The influence of enhanced EPS production on the rheological properties of fermented milk is described for engineered strains of S. thermophilus which produce different levels of EPSs.

Testing soccer players

To cope with the physiological demands of soccer, players must be competent across several fitness components. The use of fitness tests in the laboratory and field assist in examining soccer players' capabilities for performance both at the amateur and elite levels. Laboratory tests provide a useful indication of players' general fitness. Accurate test results can be obtained with the use of a thorough methodology and reliable equipment. Laboratory tests are used sparingly during the season because of the time-consuming nature of the tests. Instead, tests are generally carried out at the start and end of the pre-season period to evaluate the effectiveness of specific training interventions. Field tests provide results that are specific to the sport and are therefore more valid than laboratory tests. The reduced cost, use of minimal equipment and the ease with which tests can be conducted make them more convenient for extensive use throughout the season. Although data from laboratory and field tests provide a good indication of general and soccer-specific fitness, individual test results cannot be used to predict performance in match-play conclusively because of the complex nature of performance in competition. Fitness tests in conjunction with physiological data should be used for monitoring changes in players' fitness and for guiding their training prescription.

Nimodipine and Microsurgery Induced Recovery of the Vocal Cord after Recurrent Laryngeal Nerve Resection

Transection of the recurrent laryngeal nerve leads to permanent palsy of the vocal cord. Experimental studies have confirmed that nimodipine increases the pace of axonal regeneration. We present a case of a 19-year-old male, suffering a thyroid cancer disease, who was subjected to unilateral resection of the recurrent laryngeal nerve during surgery. The nerve was repaired with a nerve graft and the patient further treated with nimodipine for 3 months. Evaluation of the patient showed normalization of voice, movement of the vocal cord on the injured side, and electromyography evidence of reinnervation of the larynx muscles at 15 months after surgery.

Tissue-specific regulation of lipoprotein lipase in humans: effects of fasting

BACKGROUND

We have previously reported that the activity of lipoprotein lipase (LPL) measured in postheparin plasma from humans fasted for 30 h is increased relative to the fed state. This is in contrast to laboratory animals, where the strong down-regulation of LPL in their adipose tissue on fasting is reflected in decreased levels of LPL activity in postheparin plasma.

MATERIALS AND METHODS

To search for the tissue source of the increase in LPL activity on fasting of humans, young, healthy subjects were fasted for 10, 20 or 30 h, and LPL was measured in plasma (pre- and postheparin) and in biopsies from subcutaneous adipose tissue (abdominal) and from a skeletal muscle (tibialis anterior). Both LPL activity and LPL protein mass were measured in the tissue homogenates. Values after fasting were compared with values from postprandial samples obtained 2 h after a meal.

RESULTS

Fasting for up to 30 h did not alter LPL activity in basal plasma (preheparin). LPL activity in postheparin plasma remained unchanged after 10 and 20 h of fasting, but was increased by 50% after 30 h (P < 0.05). Ten hours of fasting caused a 25% (P < 0.05) decrease in LPL activity in subcutaneous adipose tissue, while LPL activity in skeletal muscle remained unchanged. After 30 h of fasting, both LPL activity and mass had decreased by approximately 50% (P < 0.05) in adipose tissue, but had increased by approximately 100% (P < 0.05) in muscle.

CONCLUSIONS

The increase in postheparin plasma LPL activity after 30 h of total food deprivation of healthy human subjects seemed to reflect an increased activity and mass of LPL in skeletal muscle.

Lipids as cofactors in protein folding: stereo-specific lipid-protein interactions are required to form HAMLET (human alpha-lactalbumin made lethal to tumor cells)

Proteins can adjust their structure and function in response to shifting environments. Functional diversity is created not only by the sequence but by changes in tertiary structure. Here we present evidence that lipid cofactors may enable otherwise unstable protein folding variants to maintain their conformation and to form novel, biologically active complexes. We have identified unsaturated C18 fatty acids in the cis conformation as the cofactors that bind apo alpha-lactalbumin and form HAMLET (human alpha-lactalbumin made lethal to tumor cells). The complexes were formed on an ion exchange column, were stable in a molten globule-like conformation, and had attained the novel biological activity. The protein-fatty acid interaction was specific, as saturated C18 fatty acids, or unsaturated C18:1trans conformers were unable to form complexes with apo alpha-lactalbumin, as were fatty acids with shorter or longer carbon chains. Unsaturated cis fatty acids other than C18:1:9cis were able to form stable complexes, but these were not active in the apoptosis assay. The results demonstrate that stereo-specific lipid-protein interactions can stabilize partially unfolded conformations and form molecular complexes with novel biological activity. The results offer a new mechanism for the functional diversity of proteins, by exploiting lipids as essential, tissue-specific cofactors in this process.

Alpha-lactalbumin unfolding is not sufficient to cause apoptosis, but is required for the conversion to HAMLET (human alpha-lactalbumin made lethal to tumor cells)

HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a complex of human alpha-lactalbumin and oleic acid (C18:1:9 cis) that kills tumor cells by an apoptosis-like mechanism. Previous studies have shown that a conformational change is required to form HAMLET from alpha-lactalbumin, and that a partially unfolded conformation is maintained in the HAMLET complex. This study examined if unfolding of alpha-lactalbumin is sufficient to induce cell death. We used the bovine alpha-lactalbumin Ca(2+) site mutant D87A, which is unable to bind Ca(2+), and thus remains partially unfolded regardless of solvent conditions. The D87A mutant protein was found to be inactive in the apoptosis assay, but could readily be converted to a HAMLET-like complex in the presence of oleic acid. BAMLET (bovine alpha-lactalbumin made lethal to tumor cells) and D87A-BAMLET complexes were both able to kill tumor cells. This activity was independent of the Ca(2+)site, as HAMLET maintained a high affinity for Ca(2+) but D87A-BAMLET was active with no Ca(2+) bound. We conclude that partial unfolding of alpha-lactalbumin is necessary but not sufficient to trigger cell death, and that the activity of HAMLET is defined both by the protein and the lipid cofactor. Furthermore, a functional Ca(2+)-binding site is not required for conversion of alpha-lactalbumin to the active complex or to cause cell death. This suggests that the lipid cofactor stabilizes the altered fold without interfering with the Ca(2+)site.

Conformational analysis of HAMLET, the folding variant of human alpha-lactalbumin associated with apoptosis

A combination of hydrogen/deuterium (H/D) exchange and limited proteolysis experiments coupled to mass spectrometry analysis was used to depict the conformation in solution of HAMLET, the folding variant of human alpha-lactalbumin, complexed to oleic acid, that induces apoptosis in tumor and immature cells. Although near- and far-UV CD and fluorescence spectroscopy were not able to discriminate between HAMLET and apo-alpha-lactalbumin, H/D exchange experiments clearly showed that they correspond to two distinct conformational states, with HAMLET incorporating a greater number of deuterium atoms than the apo and holo forms. Complementary proteolysis experiments revealed that HAMLET and apo are both accessible to proteases in the beta-domain but showed substantial differences in accessibility to proteases at specific sites. The overall results indicated that the conformational changes associated with the release of Ca2+ are not sufficient to induce the HAMLET conformation. Metal depletion might represent the first event to produce a partial unfolding in the beta-domain of alpha-lactalbumin, but some more unfolding is needed to generate the active conformation HAMLET, very likely allowing the protein to bind the C18:1 fatty acid moiety. On the basis of these data, a putative binding site of the oleic acid, which stabilizes the HAMLET conformation, is proposed.

Clara cell protein as a biomarker for ozone-induced lung injury in humans

Exposure to ozone (O3) impairs lung function, induces airway inflammation and alters epithelial permeability. Whilst impaired lung function and neutrophilia have been observed at relatively low concentrations, altered lung epithelial permeability is only seen after high-dose challenges. The appearance of Clara cell protein (CC16) in serum has been proposed as a sensitive marker of lung epithelial injury. Here, the use of CC16 as an injury biomarker was evaluated under a controlled exposure to O3 and the relationship between this marker of lung injury and early lung function decrements was investigated. Subjects (n=22) were exposed on two separate occasions to 0.2 parts per million O3 and filtered air for 2 h. Blood samples were drawn and lung function assessed at 2 h pre-exposure, immediately before and immediately after exposure as well as 2 and 4 h postexposure. O3 increased CC16 serum concentrations at 2 h (12.0+/-4.5 versus 8.4+/-3.1 microg x L(-1)) and 4 h postexposure (11.7+/-5.0 versus 7.9+/-2.6 microg x L(-1)) compared with air concentrations. Archived samples from O3 studies utilising the same design indicated that this increase was sustained for up to 6 h postexposure (9.1+/-2.6 versus 7.1+/-1.7 microg x L(-1)) with concentrations returning to baseline by 18 h (7.7+/-2.9 versus 6.6+/-1.7 microg x L(-1)). In these studies, the increased plasma CC16 concentration was noted in the absence of increases in traditional markers of epithelial permeability. No association was observed between increased CC16 concentrations and lung function changes. To conclude, Clara cell protein represents a sensitive and noninvasive biomarker for ozone-induced lung epithelial damage that may have important uses in assessing the health effects of air pollutants in future epidemiological and field studies.

Oral cancer after using Swedish snus (smokeless tobacco) for 70 years - a case report

Whereas the smoking habit has declined significantly in Sweden in recent decades, there has been a marked increase in the consumption of 'snus' (oral moist snuff). The use of this smokeless tobacco, exposing the user locally to carcinogenic nitrosamines, raises the question - will the increasing use of snuff eventually lead to a greater incidence of oral cancer? We report the case of a 90-year-old man who developed a localized squamous cell carcinoma in the gingival fold under the upper lip, at the exact place where he had regularly placed loose oral snuff for 70 years. Although this is a reminder of a prevailing cancer risk, the time frame indicates that the risk is slight. This is consistent with recent epidemiological reports regarding the minor risk of snuff-associated cancer in the Scandinavian countries.

HAMLET kills tumor cells by an apoptosis-like mechanism--cellular, molecular, and therapeutic aspects

HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a protein-lipid complex that induces apoptosis-like death in tumor cells, but leaves fully differentiated cells unaffected. This review summarizes the information on the in vivo effects of HAMLET in patients and tumor models on the tumor cell biology, and on the molecular characteristics of the complex. HAMLET limits the progression of human glioblastomas in a xenograft model and removes skin papillomas in patients. This broad anti-tumor activity includes >40 different lymphomas and carcinomas and apoptosis is independent of p53 or bcl-2. In tumor cells HAMLET enters the cytoplasm, translocates to the perinuclear area, and enters the nuclei where it accumulates. HAMLET binds strongly to histones and disrupts the chromatin organization. In the cytoplasm, HAMLET targets ribosomes and activates caspases. The formation of HAMLET relies on the propensity of alpha-lactalbumin to alter its conformation when the strongly bound Ca2+ ion is released and the protein adopts the apo-conformation that exposes a new fatty acid binding site. Oleic acid (C18:1,9 cis) fits this site with high specificity, and stabilizes the altered protein conformation. The results illustrate how protein folding variants may be beneficial, and how their formation in peripheral tissues may depend on the folding change and the availability of the lipid cofactor. One example is the acid pH in the stomach of the breast-fed child that promotes the formation of HAMLET. This mechanism may contribute to the protective effect of breastfeeding against childhood tumors. We propose that HAMLET should be explored as a novel approach to tumor therapy.

Higher drive for thinness in adolescent males with insulin-dependent diabetes mellitus compared with healthy controls

Eating behaviour in adolescent males with insulin-dependent diabetes mellitus (IDDM) living in central Sweden was compared with that of healthy age-matched male controls using the Eating Disorder Inventory for Children and an interview. The patients were heavier than controls (p = 0.004) and had higher Drive for Thinness scores (p = 0.002). None was diagnosed as having a current eating disorder.

CONCLUSION

The results of the study may indicate an increased risk of future eating disorders in males with IDDM.