High incidence of type 2 diabetes in a population with normal range body mass index and individual prediction nomogram in Vietnam

AIMS

The study aimed at determining 5-year incidence and prediction nomogram for new-onset type 2 diabetes (T2D) in a middle-aged population in Vietnam.

METHODS

A population-based prospective study was designed to collect socio-economic, anthropometric, lifestyle and clinical data. Five-year T2D incidence was estimated and adjusted for age and sex. Hazard ratio (HR) for T2D was investigated using discrete-time proportional hazards model. T2D prediction model entering the most significant risk factors was developed using the multivariable logistic-regression algorithm. The corresponding prediction nomogram was constructed and checked for discrimination, calibration and clinical usefulness.

RESULTS

The age- and sex-adjusted incidence was 21.0 cases (95% CI: 12.2-40.0) per 1000 person-years in people with mean BMI of 22.2 (95% CI: 21.9-22.7 kg/m² ). The HRs (95% CI) for T2D were 1.14 (1.05-1.23) per 10 mmHg systolic blood pressure, 1.05 (1.03-1.08) per 1 cm waist circumference, 1.40 (1.13-1.73) per 1 mmol/L fasting blood glucose, 1.77 (1.15-2.71) per sleeping time (<6 h/day vs 6-7 h/day) and 2.12 (1.25-3.61) per residence (urban vs rural). The prediction nomogram for new-onset T2D had a good discrimination (area under curve: 0.711, 95% CI: 0.666-0.755) and fit calibration (mean absolute error: 0.009). For the predicted probability thresholds between 0.03 and 0.36, the nomogram showed a positive net benefit, without increasing the number of false positives.

CONCLUSION

This study highlighted an alarmingly high incidence of T2D in a middle-aged population with a normal range BMI in Vietnam. The individual prediction nomogram with decision curve analysis for new-onset T2D would be valuable for early detection, intervention and treatment of the condition.

Population dynamics of shrimps in littoral marine waters of the Mekong Delta, south of Viet Nam

The population dynamics of eight commercial species of shrimp (Haliporoides sibogae, Harpiosquilla harpax, Metapenaeus affinis, Metapenaeus brevicornis, Metapenaeus tenuipes, Parapenaeopsis cultrirostris, Parapenaeopsis gracillima and Parapenaeus maxilipedo) distributed in littoral marine zone of the Mekong Delta were investigated. Length-based stock assessment using FiSAT II software package was used to assess the growth and mortality parameters: Asymptotic size (L8), growth coefficient (K), total (Z) and natural (M) mortality, exploitation rate (E), recruitment pattern, current probability of capture and selectivity of fishing gears. Yield-per-recruit analyses were carried out showing different levels of the exploitation. Results showed that the maximum sustainable yield would be reached for an exploitation rate higher than the current one for each population. However, the size of first capture should be increased for every population. The findings indicated that the current exploitations of shrimp populations distributed in littoral marine zone of the Mekong Delta are under exploitation level for maximum sustainable yield; however, all the shrimp populations are subject to growth over-exploitation.

Biology and population dynamics of the goby Pseudapocryptes elongatus in the coastal mud flat areas of the Mekong Delta, Vietnam

This study describe the reproductive biological characteristics and population parameters of the goby, Pseudapocryptes elongatus (Cuvier, 1816), in the coastal mud flat areas of the Mekong Delta, Vietnam. A total of 1058 specimens was collected from January 2004 to June 2005 and results showed that the breeding season occurred with two spawning peaks in July and October. Length at first maturity (L(m)) was 15.4 and 16.3 cm for females and males, respectively. The batch fecundity estimates ranged from 2,652 to 29,406 hydrated oocytes per ovary in the fish ranging from 12.8 to 22.4 cm TL. Length frequency data of the goby ranging from 9.0 to 24.0 cm TL were analyzed using the FiSAT II software. The von Bertalanffy growth parameters were determined as L8 = 25.9 cm, K = 0.66 year(-1) and t(o) = - 0.26 year(-1). The longevity (t(max)) of the goby was estimated to be 4.55 years. There were two recruitment peaks with very different magnitudes and the means of these two peaks were separated by an interval of 5 months. Length at first capture (L(c)) was 10.05 cm, the instantaneous fishing mortality rate (F = 1.38 year(-1)) and natural mortality rate (M = 1.46 year(-1)) accounted for 49 and 51% of the total mortality (Z = 2.84 year(-1)), respectively. Relative yield-per-recruit and biomass-per-recruit analyses gave E(max) = 0.65, E0.1 = 0.55 and E0.5 = 0.33. Results show that the fish stock is subjected to growth overexploitation.

Intramolecular ditryptophan crosslinks enforce two types of antiparallel beta structures

BACKGROUND

Two types of biaryl crosslinks can be formed with natural protein sidechains: ditryptophan and dityrosine. Biaryl crosslinks have the same topology as disulfide crosslinks, yet little is known about their effect on local peptide structure.

RESULTS

Three ditryptophan-linked peptide dimers based on the sequence Ac-Leu-Trp-Ala-COX were prepared. The tripeptide dimer with -CONH(2) termini was too insoluble to study, but the tripeptide dimer with -COOMe termini crystallized from methanol/chloroform as an antiparallel beta-sheet. The tripeptide dimer with a -CONMe(2) termini adopted a slipped antiparallel beta structure in methanol/chloroform.

CONCLUSIONS

These results suggest that intermolecular ditryptophan crosslinks that join the middle of peptide chains can confer a preference for antiparallel beta-sheet structure. The effect is most dramatic when both the inside and outside edges of the dimer can form hydrogen bonds as in the crystal structure of dimer 3b.

Genetic linkage of HLA-class II locus to mite-specific IgE immune responsiveness

BACKGROUND

IgE response to common inhalant allergens seems to be the major determinant of the development of atopic rhinitis and asthma but it has been difficult to demonstrate genetic control of the IgE response.

OBJECTIVE

To investigate genetic linkage between specific IgE reactions to purified aero-allergens (grass, birch, cat, mite) and the HLA-class II locus.

METHODS

DNA-based HLA-class II typing was performed for determination of DRB1, DQB1 and DPB1 alleles. Linkage was studied by the affected sibpair method and the extended transmission disequilibrium test in 100 children from 40 nuclear families selected from a homogeneous population in south-western Germany.

RESULTS

Significant linkage of mite-specific IgE response to HLA-DPB (P = 0.00001), HLA-DRB (0.02) and HLA-DQB (P = 0.001) was revealed by sibpair analysis of MHC class II alleles and confirmed by the extended transmission disequilibrium test for HLA-DRB (P = 0.01) and HLA-DPB (P = 0.04). No consistent significant linkage between the HLA-class II locus and IgE response to grass pollen, birch pollen, and cat dander could be demonstrated.

CONCLUSION

The findings are consistent with the existence of one or more genes in the HLA-class II region modifying the IgE immune response to common environmental allergens.

Control of ditryptophan cross-linking: dihydrotryptophan as a tryptophan precursor in peptide synthesis

In neat trifluoroacetic acid, tryptophan side chains cross-link to form a diastereomeric mixture of tryptophan dimers. Convergent oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) converts tryptophan dimers to ditryptophan. Since cross-link formation is under thermodynamic control, there has been no simple way of controlling the regiochemistry of the cross-linking process when more than one tryptophan side chain is present. Here, we show that dihydrotryptophan (Dht) can be incorporated into peptides as a tryptophan precursor, which reforms tryptophan upon treatment with DDQ. Dihydrotryptophan was prepared as a mixture of gammaS and gammaR diastereomers and the indoline nitrogen was protected with a Cbz group. The resulting amino acid, Nalpha-BOC-Dht(Cbz)-OH, was then incorporated into peptides as a mixture of diastereomers. Dht was resistant to tryptophan cross-linking in neat trifluoroacetic acid and was converted back to tryptophan during convergent oxidation of tryptophan dimers. While Dht is useful for control of ditryptophan regiochemistry and as a potential tryptophan analog, it is not a general strategy for Trp protection since DDQ is unlikely to be compatible with easily oxidized amino acids such as cysteine.