MODY 2: Mutation identification and molecular ancestry in a Brazilian family

Maturity Onset Diabetes of the Young (MODY) is a heterogeneous group of genetic diseases characterized by a primary defect in insulin secretion and hyperglycemia, non-ketotic disease, monogenic autosomal dominant mode of inheritance, age at onset less than 25 years, and lack of auto-antibodies. It accounts for 2–5% of all cases of non-type 1 diabetes. MODY subtype 2 is caused by mutations in the glucokinase (GCK) gene. In this study, we sequenced the GCK gene of two volunteers with clinical diagnosis for MODY2 and we were able to identify four mutations including one for a premature stop codon (c.76C>T). Based on these results, we have developed a specific PCR-RFLP assay to detect this mutation and tested 122 related volunteers from the same family. This mutation in the GCK gene was detected in 21 additional subjects who also had the clinical features of this genetic disease. In conclusion, we identified new GCK gene mutations in a Brazilian family of Italian descendance, with one due to a premature stop codon located in the second exon of the gene. We also developed a specific assay that is fast, cheap and reliable to detect this mutation. Finally, we built a molecular ancestry model based on our results for the migration of individuals carrying this genetic mutation from Northern Italy to Brazil.     

Use of Wishart Prior and Simple Extensions for Sparse Precision Matrix Estimation

A conjugate Wishart prior is used to present a simple and rapid procedure for computing the analytic posterior (mode and uncertainty) of the precision matrix elements of a Gaussian distribution. An interpretation of covariance estimates in terms of eigenvalues is presented, along with a simple decision-rule step to improve the performance of the estimation of sparse precision matrices and associated graphs. In this, elements of the estimated precision matrix that are zero or near zero can be detected and shrunk to zero. Simulated data sets are used to compare posterior estimation with decision-rule with two other Wishart-based approaches and with graphical lasso. Furthermore, an empirical Bayes procedure is used to select prior hyperparameters in high dimensional cases with extension to sparsity.     

Stone Throwing as a Sexual Display in Wild Female Bearded Capuchin Monkeys,Sapajus libidinosus

Capuchin monkeys (Sapajus spp.) in captive settings frequently manipulate and throw objects. In the wild, they may push or drop stones and sticks toward targets during inter- or intraspecific threat displays. In addition, female capuchin monkeys exhibit a broad repertoire of behaviors during their proceptive period, including facial expressions, vocalizations, stereotyped body postures, and touch-and-run behavior. This study reports stone throwing as a newly-described communicative behavior during the proceptive display of females in a group of bearded capuchin monkeys (S. libidinosus) in Serra da Capivara National Park, Brazil. During a two-year study, three females from one group were seen throwing stones at males during their proceptive phase. After this period, three other females in the same group exhibited the same behavior. Although it may be possible that this pattern is the result of several independent innovations by each female, the apparent absence of this behavior in other groups leads us to suggest that we have documented the diffusion of a new behavioral trait or tradition within this capuchin social group.     

Decrease in insulin-containing secretory granules and mitochondrial gene expression in mouse pancreatic islets maintained in culture following streptozotocin exposure

We have previously described a preferential reduction in the secretory response to nutrient secretagogues in pancreatic mouse islets maintained in culture after in vitro exposure to streptozotocin (SZ). This reduction was associated with an impaired substrate metabolism at the mitochondrial level. To further clarify this issue, mouse pancreatic islets were exposed in vitro to 2.2 mM SZ for 30 min. At 4 h after SZ treatment ultrastructural changes were apparent in the endoplasmic reticulum and Golgi areas of the B-cells. However, 2 and 6 days following SZ exposure the B-cells appeared well preserved, except for a marked decrease in the number of insulin-containing secretory granules. A morphometric analysis of the B-cells 6 days after SZ exposure showed a normal B-cell size and a normal volume fraction of B-cell mitochondria. However, there was a decrease in total islet size and a 13% decrease in the volume fraction of B-cells in the islets. These mouse islets exhibited a decreased content of the mitochondrial DNA-encoded cytochrome b mRNA, as evaluated by dot-blot analysis. As a whole, the data obtained indicate that SZ treatment does not induce a decrease in the number of mitochondria or long-lasting ultrastructural damage to this organelle. However, there is a clear decrease in the cytochrome b mRNA, suggesting that SZ can induce damage to the mitochondrial DNA.     

Distribution of sulphate and iduronic acid residues in heparin and heparan sulphate

1. A method was developed for determination of the uronic acid composition of heparin-like glycosaminoglycans. Polymers or oligosaccharides are degraded to monosaccharides by a combination of acid hydrolysis and deamination with HNO₂. The resulting uronic acid monosaccharides (accounting for about 70% of the uronic acid contents of the starting materials) are isolated and converted into the corresponding aldono-1,4-lactones, which are separated by g.l.c. The calculated ratios of glucuronic acid/iduronic acid are reproducible within 5%. 2. Samples of heparin from pig intestinal mucosa (molar ratio of sulphate/disaccharide unit, 2.40) and heparan sulphate from human aorta (sulphate/disaccharide ratio, 0.46) were subjected to uronic acid analysis. l-Iduronic acid constituted 77% and 19% respectively of the total uronic acid contents. 3. The correlation between the contents of sulphate and iduronic acid indicated by this finding also applied to the fractionated deamination products of the two polymers. The sulphated fragments varied in size from disaccharide to octasaccharide (or larger) and showed sulphate/disaccharide molar ratios in the range of 0.05–2.0. The proportion of iduronic acid increased with increasing ester sulphate contents of the oligosaccharides. 4. Previous studies on the biosynthesis of heparin in a cell-free system have shown that l-iduronic acid residues are formed by C-5 epimerization of d-glucuronic acid units at the polymer level; the process requires concomitant sulphation of the polymer. The results obtained in the present structural study conform to these findings, and suggest further that similar mechanisms may operate in the biosynthesis of heparan sulphate. The epimerization reaction appears to be linked to the sulphation of hydroxyl groups but does not seem to require sulphation of the target uronic acid residues. The significance of sulphamino groups in relation to the formation of iduronic acid is unknown.     

Incidence of peptic ulcer disease in Gothenburg, 1985.

OBJECTIVE--To determine the incidence and age distribution of peptic ulcer disease in adults in Gothenburg. DESIGN--Retrospective study of patients with symptoms over one year. SETTING--All gastroenterology and x ray departments. PATIENTS--Any patient found to have an active ulcer crater during 1985. MAIN OUTCOME MEASURES--Sex, age, past history of gastrointestinal ulcers, and smoking habit. RESULTS--In 1985, 1402 peptic ulcers were diagnosed in 1137 adults. Over half (403; 54%) of the ulcers in men and 393 (60%) ulcers in women were in patients aged over 60. All types of ulcer showed increasing incidence with age. The sex ratio of patients aged 40-50 with peptic ulcers was 1:1. Nearly half (109; 48%) of ulcers diagnosed for the first time in men and 129 (57%) of such ulcers in women were in patients aged over 60. Elderly men and women were also more likely to develop haemorrhage. CONCLUSIONS--In Gothenburg there is a surprisingly high incidence of peptic ulcer disease, which increases considerably with age, possibly explained by the availability of modern diagnostic techniques as 1121 (80%) ulcers had been diagnosed by gastroscopy. Compared with earlier studies there was no difference in the incidence between men and women aged 40-50.     

Geographic differences in the allele frequencies of the human Y-linked tetranucleotide polymorphism DYS19

We have studied the allele frequency distribution of the microsatellite locus DYS 19 in several populations with different geographical origins worldwide. Three new alleles were found. In addition, remarkable geographic and ethnic differences were observed in the allele frequency profiles and DNA marker (gene) diversity among populations and major ethnic groups. Amerindians showed an overwhelming predominance of the A allele, while in Caucasians the B allele was modal, and in Greater Asians and Africans allele C became predominant. Even within these geographic regions there were significant gradients, as exemplified by the decreasing frequency profile of the B allele from Great Britain over Germany to Slovakia. Thus, DYS 19 emerges as a useful tool for studying the structure and dynamics of human populations.