Relative handgrip strength correlates inversely with increased body fat, inflammatory markers and increased serum lipids in young, healthy adults - The LBA study.

BACKGROUND: Handgrip strength (HGS) is a surrogate marker of whole body strength that has been observed to correlate inversely with the metabolic syndrome (MetS). In this study, we examined whether HGS in young, healthy individuals, was associated with surrogate endpoints of the MetS. A secondary goal was to examine whether absolute HGS (absHGS) or relative HGS (relHGS) was a stronger predictor of MetS. METHOD: 834 subjects (577 women), aged 18-26, were recruited. Surrogate endpoints for MetS were waist circumference, HDL, fasting glucose, fasting insulin, triglycerides, and systolic and diastolic blood pressure (BP). We also examined the association between HGS and body fat percentage, HOMA-IR, CRP, orosomucoid and apolipoprotein A-1 and apolipoprotein B. The associations were examined using multivariable linear regression. RESULTS: AbsHGS and relHGS were each associated with several surrogate endpoints of the metabolic syndrome, with RelHGS being statistically significantly associated with a greater number of the variables - all except fasting glucose and diastolic BP. CONCLUSION: RelHGS correlates with components of the MetS even in young, healthy populations. It is a better predictor of MetS components than absHGS. As a cheap and easy to use biomarker, relHGS holds merit as a screening tool for metabolic dysfunction even in preclinical contexts.

CTH G1208T and MTHFR A1298C polymorphisms are associated with a higher risk of a first myocardial infarction with fatal outcome among women.

OBJECTIVES: Cystathionine-gamma-lyase (CSE) in the transsulfuration pathway generates hydrogen sulfide (H2S), suggested regulating cardiovascular function. The G1208T polymorphism in the CTH gene, rs1021737, has, in addition to MTHFR, been found to increase homocysteine, related to myocardial infarction (MI) risk. This study aimed, for the first time, to investigate the associations of the polymorphisms CTH G1208T, MTHFR C677T, and A1298C with the prospective risk of developing a fatal or non-fatal first MI. METHODS: This case-referent study included 545 cases later developing a first-ever MI and 1,054 referents from the Northern Sweden Health and Disease Study. Fatal MI was defined as death within 28 days after MI symptoms. RESULTS: Women, but not men, had a positive association between fatal MI and the CTH G1208T, odds ratio [95% confidence interval] 3.14 [1.16-8.54] for heterozygotes, and the dominant model 3.22 [1.22-8.51], and for the MTHFR A1298C heterozygotes 3.24 [1.26-8.34] and the dominant model 2.63 [1.06-6.50]. The MTHFR C677T polymorphism was not related to MI. CONCLUSIONS: This study indicates that the minor alleles of CTH G1208T and MTHFR A1298C polymorphisms are associated with a higher risk for a fatal MI among women but not for non-fatal MI. No association was found in men.

Handgrip strength reference intervals in Swedish, young, healthy adults: The LBA study.

OBJECTIVES: Handgrip strength (HGS) is a surrogate marker of general risk and nutritional status, frequently used in clinical practice. This study aimed to determine clinically useful reference intervals for healthy, young adults from Northern Europe. METHODS: This cross-sectional study was conducted in central Sweden, recruiting 834 young, nonsmoking adults ages 18 to 26 y. Subjects responded to a questionnaire on general health status, medication (including contraceptives), exercise habits, and parental and their own country of birth. Anthropometry, bioimpedance analysis for determination of fat-free mass (FFM), and HGS was measured. Reference intervals were calculated as mean and standard deviation. Differences between men, women, and women using estrogen contraceptives were analyzed using an analysis of variance with Tukey's post hoc test. Associations between HGS and determinant variables were analyzed using Spearman and linear regressions. RESULTS: Men and women differed in HGS, but no significant difference was found in average HGS based on contraceptive use in women. Mean HGS was 53 kg in men and 34 kg in women, with a range of 22 kg to 90 kg in men and 16 kg to 73 kg in women. Height correlated with HGS. Subjects with a body mass index (BMI) <20 had statistically significantly lower HGS than those in higher BMI groups. There was no statistically significant mean difference between the group of subjects with a BMI of 20 to 25 and those with BMI >25 in neither men nor women. HGS in both sexes showed a gradual increase through tertiles of FFM. In linear regression models, sex, height, and FFM were the main determinants of HGS. CONCLUSIONS: In this study, we established reference intervals for HGS in healthy Swedish adults ages 18 to 26 y. As a surrogate marker of whole-body muscle mass, these reference intervals can be used in health assessments and the planning of health-promoting measures in the individual young adults. Differences in HGS based on height warrant height-specific reference intervals that should be established locally.

Plasma Cotinine Is Positively Associated with Homocysteine in Smokers but Not in Users of Smokeless Tobacco.

Plasma total homocysteine (tHcy) is a risk marker, and smoking is an established risk factor for cardiovascular disease. It is unclear if the effect of smoked tobacco on homocysteine is mediated by nicotine or other combustion products in smoked tobacco. Snus (moist smokeless tobacco) is high nicotine-containing tobacco, and little is known about the effect of snus on plasma homocysteine. Therefore, we studied, in a cross-section of subjects (n = 1375) from the Northern Sweden Health and Disease Study, with strictly defined current smokers (n = 194) and snus users (n = 47), the impact of tobacco exposure on tHcy, assessed by self-reported tobacco habits and plasma cotinine concentrations. The snus users had higher cotinine concentrations than the smokers. Cotinine, creatinine, methylmalonic acid, and the methylenetetrahydrofolate reductase genotype (MTHFR) T allele were positively associated with tHcy among the smokers, but not among the snus users. No association was observed between tHcy and the number of cigarettes/day. There was a positive association between cotinine and tHcy in the smokers, but not among the snus users. This indicates that substances other than nicotine in tobacco smoke could be responsible for the differential effects on homocysteine status. Self-reported smoking should be complemented by a cotinine assay whenever possible.

Mild impairment of renal function (shrunken pore syndrome) is associated with increased risk of a future first-ever myocardial infarction in women.

Impaired renal function is associated both with the development of cardiovascular disease and its prognosis. A new syndrome called 'Shrunken Pore Syndrome' has been suggested, as the estimated glomerular filtration rate for cystatin C (eGFRcystatin C) is affected earlier due to differences in molecular size compared to eGFRcreatinine. The aim was to investigate if a lower eGFRcystatin C/eGFRcreatinine ratio in a prospective setting increases the risk of later developing a first-ever myocardial infarction (MI) independently of other cardiovascular risk factors. We used a nested case-referent study design within the Northern Sweden Health and Disease Study, and 545 subjects (29.0% women) were identified who prospectively developed a first-ever MI, and their 1054 matched referents. For women, but not for men, one standard deviation (SD) increase of ln z-scores of eGFRcystatin C/eGFRcreatinine ratio was associated with a lower risk of a future MI: odds ratio [95% confidence interval] 0.58 [0.34-0.99], adjusted for apolipoprotein B/A1 ratio, CRP, homocysteine, systolic blood pressure, body mass index, and diabetes. Furthermore, a high eGFRcreatinine associated independently with an increased risk of future MI in men only: OR 1.25 [1.05-1.48]. Thus, for women, a lower eGFRcystatin C/eGFRcreatinine ratio is associated with a higher risk of having a future first-ever MI, and it may be a valuable, easily implemented biomarker for risk of cardiovascular disease.

IGFBP-1 and IGFBP-2 are associated with a decreased pulse-wave velocity in young, healthy adults.

BACKGROUND AND AIMS: In healthy, young adults we analyzed a panel of cardiovascular disease related proteins in plasma and compared them with the vascular health of the subjects. The aim was to identify proteins with a relationship to the early atherosclerotic process in healthy individuals. METHODS: We employed the proximity extension assay from OLINK proteomics to analyze 92 cardiovascular disease (CVD) related proteins on 833 subjects (men and women, ages 18-26). The women were further divided into an estrogen-using group and non-users. Protein expression was analyzed using principal component analysis (PCA). The following vascular examinations were performed: Pulse-wave velocity (PWV), augmentation index (AIX), carotid-intima media thickness (cIMT). RESULTS: Three principal components were obtained using PCA to analyze the protein expression. None of the obtained principal components correlated significantly with AIX or cIMT. One of the components, explaining 6% of the total variance of the data, was significantly correlated with PWV. Upon examination of the proteins with the highest factor loadings on this component independently in a multivariable model, adjusting for established CVD risk biomarkers, insulin-like growth factor-binding protein 1 (IGFBP-1) and insulin-like growth factor-binding protein 2 (IGFBP-2) were found to independently, negatively correlate with PWV. Among the established risk factors included in the multivariable model, age was significantly and adversely correlated with all vascular measurements. CONCLUSIONS: In this population of healthy, young adults, groups of CVD related proteins correlate with PWV, but not AIX or cIMT. This group of proteins, of which IGFBP-1 and IGFBP-2 were independently, negatively correlated in a multivariable model with PWV, could have benificial effects on vascular stiffness. The robust association between age and PWV, AIX and cIMT provide insight into the impact of aging on the vasculature, which is detectable even in a population of young, healthy, non-smoking individuals of ages spanning only 8 years.

Factor XII Concentrations and Risk of Intracerebral Haemorrhage. A Prospective Case-Referent Study.

OBJECTIVES: In a previous pilot study, we found an association between high factor XII levels and risk of haemorrhagic stroke suggesting that factor XII is a risk marker for intracerebral haemorrhage (ICH). The aim of this study was to further investigate the association between factor XII and risk of ICH in a larger population. MATERIALS AND METHODS: This study was conducted as a prospective nested case-referent study. All participants underwent a health examination and blood sampling for factor XII analysis at baseline. Cases were defined as participants who were diagnosed with a first-ever ICH between 1985 and 2000. Two referents were matched to each case. RESULTS: We identified 70 individuals with first-ever ICH and 137 matched referents who had undergone a health examination and donated blood samples before the ICH event. The mean age was 54 years, and 33% were women. The median time-to-event was 3.5 years (range 0.04 to 10.2 years). Conditional logistic regression showed no association between factor XII and risk of ICH, (odds ratio 1.06 per SD; [95% confidence interval: 0.57-1.97] in a multivariable model). CONCLUSIONS: A previous finding of an association between high concentration of factor XII and risk of ICH could not be replicated in this larger study.

Pulse wave velocity, augmentation index, and carotid intima-media thickness are each associated with different inflammatory protein signatures in young healthy adults: The lifestyle, biomarkers and atherosclerosis study.

BACKGROUND AND AIMS: We aimed to identify plasma protein biomarkers related to inflammation that correlated with physiological measurements of vascular function and structure in healthy individuals. METHODS: We used the OLINK proteomics panel, which measures 92 inflammatory proteins, in 834 young, healthy non-smokers (ages 18-26). Principal component analysis (PCA) was employed to identify patterns of proteins. The following measurements were used: pulse-wave velocity (PWV), carotid intima-media thickness (cIMT) and augmentation index (AIX). Established cardiovascular risk factors were included in multivariable models. RESULTS: PCA showed four principal components (PC 1, PC 2, PC 3, PC 4). PC 3, comprising proteins related to hemostasis, was significantly and inversely correlated with PWV. Among the proteins with the highest factor loadings on PC 3, uPA was negatively correlated with PWV in multivariable regression models. AIX was significantly correlated with PC 2, comprising inflammatory cytokines. Among the proteins with the highest factor loadings on PC 2, interleukin-6 was significantly correlated with AIX in the multivariable model. cIMT was significantly correlated with PC 4, comprising proteins related to chemotaxis. Among the proteins with the highest factor loadings on PC 4, fractalkine was significantly correlated with cIMT in the multivariable model. CONCLUSIONS: In young, healthy individuals, OLINK inflammatory proteins correlated with measures of vascular status. Each of the three measures PWV, AIX, and cIMT, which target different parts of the vasculature, correlated with its own specific protein signature, indicating that different subsets of inflammatory mediators affect different parts of the vasculature and are detectable already in young healthy adults.

Leptin levels are not affected by enalapril treatment after an uncomplicated myocardial infarction, but associate strongly with changes in fibrinolytic variables in men.

Leptin, an adipocyte-derived hormone, is involved in the regulation of body weight and is associated with obesity-related complications, notably cardiovascular disease (CVD). A putative link between obesity and CVD could be induction of plasminogen activator inhibitor-1 (PAI-1) synthesis by leptin. In this study, we hypothesized that the beneficial effect of the angiotensin-converting enzyme inhibitor (ACEi) enalapril on PAI-1 levels is mediated by effects on leptin levels. The association between leptin and components of the fibrinolytic system was evaluated in a non-prespecified post hoc analysis of a placebo-controlled randomized, double-blind trial where the effect of the ACEi enalapril on fibrinolysis was tested. A total of 46 men and 37 women were randomized to treatment with enalapril or placebo after (median 12 months) an uncomplicated myocardial infarction. At baseline, the participants were stable and had no signs of congestive heart failure. Leptin and fibrinolytic variables (mass concentrations of PAI-1, tissue plasminogen activator (tPA) and tPA-PAI complex) were measured at baseline, and after 10 days, 6 months and 12 months. Enalapril treatment did not change leptin levels, which increased significantly during 1 year of follow-up (p = .007). Changes in leptin levels were strongly associated with changes of tPA mass (p = .001), tPA-PAI complex (p = .003) and of PAI-1 (p = .006) in men, but not in women. Leptin levels are not influenced by treatment with an ACEi. In contrast, leptin associates strongly with changes in fibrinolytic variables notably with a sex difference, which could be of importance for obesity-related CVD.

Body fat percentage and CRP correlates with a composite score of vascular risk markers in healthy, young adults - The Lifestyle, Biomarkers, and Atherosclerosis (LBA) study.

BACKGROUND: Identification of early signs of atherosclerosis in young adults have the potential to guide early interventions to prevent later cardiovascular disease. We therefore analyzed measures of vascular structure and function and biomarkers of cardiovascular risk in a sample of young healthy adults. METHODS: Pulse-wave velocity (PWV), carotid-intima media thickness (cIMT) and augmentation index (AIX) were measured in 834 healthy non-smokers (ages 18.0-25.9). Emphasis was put on discriminating between individuals having a vascular structure and function associated with a higher or lower risk, and cluster analysis algorithms were employed to assign the subjects into groups based on these vascular measurements. In addition, a vascular status score (VSS) was calculated by summarizing the results according to quintiles of the vascular measurements. The associations between VSS and cardiovascular biomarkers were examined by regression analyses. RESULTS: The cluster analyses did not yield sufficiently distinct clustering (groups of individuals that could be categorized unequivocally as having either a vascular structure and function associated with a higher or lower CVD risk). VSS proved a better classificatory variable. The associations between VSS and biomarkers of cardiovascular risk were analyzed by univariable and multivariable regressions. Only body fat percentage and C-reactive protein (CRP) were independently associated with VSS. CONCLUSIONS: A VSS calculation, which integrates PWV, cIMT, and AIX measurements is better suited for cardiovascular risk evaluation in young adults than cluster analyses. The independent associations of VSS with body fat percentage and CRP highlight the decisive role of adiposity and systemic inflammation in early atherosclerotic progression and suggests a subordinate role of insulin and lipid metabolism in this age span.

Body fat percentage is more strongly associated with biomarkers of low-grade inflammation than traditional cardiometabolic risk factors in healthy young adults - the Lifestyle, Biomarkers, and Atherosclerosis study.

The primary aim was to appraise the relationship between body fat percentage and the inflammatory markers C-reactive protein (CRP) and orosomucoid in a population of young, non-smoking, healthy, Swedish adults, without any chronic diseases. A secondary aim was to compare whether these associations differed between the women using estrogen contraceptives and those who did not. We assessed the association in linear regression models between body fat percentage based on a bio-impedance measurement and plasma concentrations of CRP and orosomucoid in men and women aged 18-26 years, n = 834. Statistically significant associations were found between body fat percentage and both biomarkers of inflammation, with ß coefficients of 0.30 (95% CI 0.24-0.37) and 0.28 (0.22-0.35) for CRP and orosomucoid, respectively (p < .001). Adjustment for established risk factors marginally lowered the effects sizes (partial betas, 0.28 and 0.20, respectively), while the strong statistically significant associations remained. In the female cohort, estrogen and non-estrogen using subpopulations did not significantly differ in the correlations between body fat percentage and the inflammatory biomarkers, even adjusted for established cardiometabolic risk factors. In conclusion, in healthy young adults, higher levels of body fat percentage are associated with elevations in plasma biomarkers of inflammation, suggesting that a systemic inflammatory process, promoting atherosclerosis, may commence already at this early stage in life. CRP and orosomucoid plasma concentrations differed between users and non-users of estrogen contraceptives, but both subgroups showed similar correlations between increasing body fat percentage and increasing plasma concentrations of the biomarkers of inflammation.

D-Dimer Is Associated With First-Ever Intracerebral Hemorrhage.

Background and Purpose- Hypertension is the most important risk factor for intracerebral hemorrhage (ICH), but further characterization is needed for groups at high risk of ICH. One way to predict the risk of developing a disease is with plasma biomarkers. This study aimed to investigate the association between the biomarker, D-dimer, and ICH risk. Methods- This population-based, nested case-control study was conducted using data from 2 population-based surveys; the Västerbotten Intervention Programme and MONICA Northern Sweden (Monitoring Trends and Determinants in Cardiovascular Disease). All participants underwent a health examination and blood sampling at baseline before the event. Cases (n=141) were diagnosed with a first-ever ICH between 1985 and March 2007. One or 2 controls (n=255) were matched to each case. Results- The median age was 60 years; 39% of participants were women; and the median time from blood sampling to ICH was 5.2 years. When D-dimer was evaluated as a continuous variable, it was significantly associated with ICH. After multivariable adjustment (for hypertension, body mass index, cholesterol levels, diabetes mellitus, and smoking), the odds ratio was 1.36 per SD of D-dimer (95% CI, 1.05-1.77). When participants were stratified in 3 groups according to time from blood sampling at health examination to ICH, we found that the association between D-dimer levels and ICH was most pronounced in individuals with the shortest time from blood sampling to ICH event (<3.5 years; odds ratio, 1.78; 95% CI, 1.05-3.05). Conclusions- High plasma concentrations of D-dimer were associated with increased risk of a future ICH, after adjusting for cardiovascular risk factors. This association was predominantly driven by the cases with the shortest time from blood sampling to ICH event.

Formate rescues neural tube defects caused by mutations in Slc25a32.

Periconceptional folic acid (FA) supplementation significantly reduces the prevalence of neural tube defects (NTDs). Unfortunately, some NTDs are FA resistant, and as such, NTDs remain a global public health concern. Previous studies have identified SLC25A32 as a mitochondrial folate transporter (MFT), which is capable of transferring tetrahydrofolate (THF) from cellular cytoplasm to the mitochondria in vitro. Herein, we show that gene trap inactivation of Slc25a32 (Mft) in mice induces NTDs that are folate (5-methyltetrahydrofolate, 5-mTHF) resistant yet are preventable by formate supplementation. Slc25a32gt/gt embryos die in utero with 100% penetrant cranial NTDs. 5-mTHF supplementation failed to promote normal neural tube closure (NTC) in mutant embryos, while formate supplementation enabled the majority (78%) of knockout embryos to complete NTC. A parallel genetic study in human subjects with NTDs identified biallelic loss of function SLC25A32 variants in a cranial NTD case. These data demonstrate that the loss of functional Slc25a32 results in cranial NTDs in mice and has also been observed in a human NTD patient.

Declarations of conflict of interest are still inadequate.

Declaration of conflicts of interest (COI, understood mainly as financial) in medical publications is long established. Most journals refer only to the guidelines of the International Committee of Medical Journal Editors (ICMJE) but not to those of the WAME (World Association of Medical Editors). We surveyed 17 journals and found only one (BJOG), which explicitly mentioned "religious interest" as an example of a possible COI and one other journal included "personal belief" (Journal of Obstetrics and Gynaecology of India) as a COI. Of the other 15 journals, 10 used the ICJME as their COI model. They were the general journals, NEJM, JAMA, Lancet, BMJ and JIM (Journal of Internal Medicine); the pediatric/neonatology journals Pediatrics and Journal of Pediatrics (this also mentions WAME) but not Acta Paediatrica, which mentions COPE; the obstetrics/gynaecology journals AJOG and IJOG; and the British Journal of Haematology but not Blood, which uses the American Society of Hematology's own COI model. Neither EJOG, JOG, IndianObs Gyn, nor J Obstet Gynaecol India clearly specified a COI model. Yet the ICMJE COI guidelines fail to include involvement in religious and/or secular groups which take sides on the subject being discussed, while the WAME guidelines specifically do so. Instead the ICMJE uses the vaguer phrase "intellectual beliefs". The actual ICJME COI-form does not itemise religion. To maintain their scientific credibility, medical journals must start requiring disclosure of such ties. A typical example where current ICMJE rules fall short is the ongoing heated debates over the ethics of prenatology and of physician assisted suicide.

Bioenergetics of acquired cisplatin resistant H1299 non-small cell lung cancer and P31 mesothelioma cells.

Acquired cisplatin resistance is a common feature of tumours following cancer treatment with cisplatin and also of non-small cell lung cancer (H1299) and mesothelioma (P31) cell lines exposed to cisplatin. To elucidate the cellular basis of acquired cisplatin resistance, a comprehensive bioenergetic analysis was undertaken. We demonstrate that cellular oxygen consumption was significantly decreased in cisplatin resistant cells and that the reduction was primarily due to reduced mitochondrial activity as a result of reduced mitochondrial abundance. The differential mitochondrial abundance was supported by data showing reduced sirtuin 1 (SIRT1), peroxisome-proliferator activator receptor-γ co-activator 1-alpha (PGC1α), sirtuin 3 (SIRT3) and mitochondrial transcription factor A (TFAM) protein expression in resistant cells. Consistent with these data we observed increased reactive oxygen species (ROS) production and increased hypoxia inducible factor 1-alpha (HIF1α) stabilization in cisplatin resistant cells when compared to cisplatin sensitive controls. We also observed an increase in AMP kinase subunit α2 (AMPKα2) transcripts and protein expression in resistant H1299 cells. mRNA expression was also reduced for cisplatin resistant H1299 cells in these genes, however the pattern was not consistent in resistant P31 cells. There was very little change in DNA methylation of these genes, suggesting that the cells are not stably reprogrammed epigenetically. Taken together, our data demonstrate reduced oxidative metabolism, reduced mitochondrial abundance, potential for increased glycolytic flux and increased ROS production in acquired cisplatin resistant cells. This suggests that the metabolic changes are a result of reduced SIRT3 expression and increased HIF-1α stabilization.

Levels of beta-trace protein in optic disc pit with macular detachment.

BACKGROUND: To report beta-trace protein (ßTP) levels in the subretinal fluid (SRF) of four patients with a macular detachment associated with optic disc pit (ODP). METHODS: Four patients with a serous retinal detachment involving the macula was operated by pars plana vitrectomy (PPV) with C2 F6 gas tamponade and peeling of internal limiting membrane (ILM). Patients with a follow-up period exceeding one year postoperatively were included in the study. The SRF was drained using a fine cannula without laser photocoagulation, and the samples were analysed using particle-enhancing nephelometry. The levels of ßTP were compared to 20 routine cerebrospinal fluid (CSF) samples. RESULTS: In four of the five samples from SRF had relatively low ßTP levels, with a mean concentration of 6.6 mg/l (range 2.0 to 23.1 mg/l) compared to 16.0 mg/l (range 6.3-26.8 mg/l) in CSF. The only SRF sample within the range corresponding to normal CSF was the first sample from patient 4, and the analysis of the renewed aspirate during the second operation was 2.8 mg/l. Postoperatively, the regression of SRF was slow, but regression of SRF in the foveal region took place in all cases; however, visual acuity (VA) was improved in only half of the patients. CONCLUSION: The results from the analysed SRF regarding ßTP concentration in these patients indicate that the SRF in ODP is not identical to CSF, as the concentrations of ßTP differ.

Ethical stumbling blocks in uncovering folate deficiency as a preventable cause of spina bifida.

The year 2016 witnessed the anniversaries of several key events related to the prevention of neural tube defects (NTD) with folate supplementation. However, the road leading up to this achievement was full of stumbling blocks, both in terms of research ethics and researcher ethics. First, the decisions of ethics review boards differed with respect to allowing placebo groups in folate trials, thus reducing the level of evidence obtained from the earliest studies. Second, statisticians insisted on analysing the outcome of a trial by intention-to-treat - which turned out to be non-significant - rather than by treatment received, which was statistically significant. Third, the recognition of positive results was stymied by the reluctance of some researchers to recognise and quote others' contributions. All this needlessly delayed the recognition of the NTD-preventive effects of folate by a decade. The story of the prevention of NTD thus offers insights into research inadequacies that have the potential to impede the advance of medical science, with the ethical aspects having the most immediate impact. Efficient ethics review boards play a major role worldwide and if they play safe, they may risk disallowing high-quality studies of great public health import.

Identification of novel genetic variants in the mutational hotspot region 14 kb upstream of the LCT gene in a Mexican population.

Several polymorphic loci linked to lactase persistence (LP) have been described, all located in a small mutational hotspot region far upstream (∼14 kb) of the lactase (LCT) gene. One is typically found in Europeans, LCT -13910C > T, several others are found in East Africans and Arabs, e.g. LCT -13907C > G and LCT -13915T > G. The possibility of similar loci, specific to populations in South and Central America, has not received much attention so far. To identify possible novel polymorphisms in the mutational hotspot region, we sampled 158 subjects from a rural area in South-Central Mexico. DNA was isolated from serum, and Sanger sequencing of a 501 bp region spanning the LCT -13910C > T hotspot was successfully performed in 150 samples. The frequency of the European-type LCT -13910 T-allele was q = 0.202, and 35% of the population was thus lactase-persistent (CT or TT). Sixteen novel genetic variants were found amongst 11 of the subjects, all were heterozygotes: seven of the subjects were also carriers of at least one LCT -13910 T-allele. Thus, the mutational hotspot region is also a hotspot in the rural Mexican population: 11/150 subjects carried a total of 16 previously unknown private mutations but no novel polymorphism was found. The relationship between such novel genetic variants in Mexicans and lactase persistence is worthy of more investigation.

Expression of claudin 1, claudin 4, and claudin 7 in colorectal cancer and its relation with CLDN DNA methylation patterns.

Altered claudin expression has been described in colon, prostatic, ovarian, and breast carcinoma. However, the role of epigenetic modifications in these genes and their role in colorectal cancer is unknown. We aimed our study to investigate whether claudin protein expression and methylation of CLDN can influence the tumorigenesis of colorectal cancer. A total of 31 patients diagnosed with colorectal carcinoma was used in this study. Immunohistochemical staining was used to study protein expression in both tumor and the adjacent nonneoplastic mucosa of claudin 1, 4, and 7. To detect the DNA methylation pattern of CLDN1, 4, and 7, genomic DNA was extracted from both the tumor and the adjacent nonneoplastic mucosa. Methylation analysis was carried out using bisulfite pyrosequencing. Cell membrane staining intensity of all claudins was found significantly lower in colorectal cancer tissues when compared to paired normal mucosa (p ≤ 0.001). For claudin 4, the percentage of cells staining positively was also significantly reduced (p = 0.04). In normal mucosa, cytoplasm showed no staining for claudins in any patient, whereas in paired colorectal cancer tissues, significant cytoplasmic staining appeared both for claudin 1 (p = 0.04) and claudin 4 (p = 0.01). Tumor samples were significantly hypomethylated in CLDN1 (p < 0.05). In conclusion, our results show that CLDN1 is significantly hypomethylated in tumor samples and that the membrane staining intensity for claudin 1, 4, and 7 is significantly lower in colorectal cancer tissues than in adjacent nonneoplastic tissue. Colorectal cancer cells showed dystopic cytoplasmic location of claudins.