The emulsifying properties of Cruciferin-rich and Napin-rich protein isolates from Brassica napus L.

The influence of pH (3.0, 5.0 and 7.0) and ionic strength (0, 50 and 100 mM NaCl) on the physicochemical and emulsifying properties of cruciferin-rich (CPI) and napin-rich (NPI) protein isolates were examined. Specifically, the surface characteristics (charge and hydrophobicity), solubility, interfacial tension and emulsifying activity (EAI) and stability (ESI) indices were measured. In the case of the cruciferin-rich protein isolate, surface charge was found to be negatively and positively charged at pHs above and below its isoelectric point (~4.6-4.8), respectively, ranging in potential from -33 mV at pH 8.0 to +33 mV at pH 3.0. In the presence of NaCl, the overall magnitude of charge became reduced at all pHs. In contrast, hydrophobicity, solubility and the ability for CPI to reduce interfacial tension all were found to be dependent upon both pH and NaCl concentration. Solubility was found to be lowest at pH 5.0 (~11%) and 7.0 (16%) for CPI without salt, but was significantly improved with the addition of NaCl (>80%). Interfacial tension was found to be lowest (10-11 mN/m) for pH 5.0 – 0 mM NaCl and pH 7.0 – 50/100 mM NaCl. Overall, the presence of salt reduced EAI with increasing levels of NaCl at pH 5.0 and 7.0, but not at pH 3.0. In contrast, ESI became reduced with the addition of NaCl (regardless of the concentration) from ~15.7 min at 0 mM NaCl to ~12 min with 50/100 mM NaCl, from ~14.7 min at 0 mM NaCl to ~11.5 min with 50/100 mM NaCl and from 15.1 min at 0 mM NaCl to ~11.7 min with 50/100 mM NaCl for pH 3.0, 5.0 and 7.0, respectively. ESI also was found to be unaffected by pH. In the case of a napin-rich protein isolate, surface charge for the NPI in the absence of NaCl ranged between ~ +10 mV to ~ -5 mV depending on the pH, becoming electrically neutral at pH 6.6. The addition of NaCl acted to reduce the surface charge on the NPI and caused a shift in its isoelectric point to pH 3.5 and 3.9 for the 50 and 100 mM NaCl levels, respectively. Overall, surface hydrophobicity for the NPI was reduced as the pH increased, whereas as NaCl levels were raised the hydrophobicity declined. In contrast, NPI solubility was found to be high (~93-100%) regardless of the solvent conditions. The ability of NPI to reduce interfacial tension was enhanced at higher pHs, however the effect of NaCl was pH dependent. Overall, EAI values were similar in magnitude at pH 3.0 and 5.0, and lower at pH 7.0. The effect of NaCl on EAI was similar at pH 3.0 and 7.0, where EAI at the 0 mM and 100 mM NaCl levels were similar in magnitude, but increased significantly at 50 mM NaCl. However, the EAI values at pH 5.0 were reduced as the level of NaCl increased. Overall, the stability of NPI-stabilized emulsions degraded rapidly and the addition of salt induced faster emulsion instability. In summary, CPI and NPI were very different in terms of their physicochemical properties. However, the emulsifying properties were similar in magnitude indicating that they had similar emulsifying potential under the solvent conditions examined

Serum beta-2 microglobulin concentration predicts cardiovascular and all-cause mortality.

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Increasing prevalence of hypertension in Hong Kong Cardiovascular Risk Factor Prevalence Study: role of general and central obesity

Introduction: General obesity and central obesity are well-known risk factors of hypertension. We investigated the change in the prevalence of hypertension in the population-based prospective Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS) and the relationship of change in blood pressure with change in body mass index (BMI) and waist circumference over a follow-up period of 11.9 years. Methods: A total of 2888, 1942 and 1798 subjects in CRISPS-1 (1995-1996), CRISPS-2 (2000-2004) and CRISPS-3 (2005-2008) were included in this analysis respectively. Hypertension was defined as blood pressure ≥140/90 mm Hg or taking anti-hypertensive medication. General obesity was defined as BMI ≥27.5 kg/m2 and central obesity was defined as waist circumference ≥90 cm in men or ≥80 cm in women. Results: The prevalence of hypertension increased from 18.1% to 39.4% (P<0.001 after adjusting for age and sex). The prevalence of central obesity increased from 25.4% to 41.4%, but that of general obesity decreased from 16.8% to 14.8% (both P<0.001 after adjusting for age and sex). Among 1347 subjects who did not take any anti-hypertensive medication at both CRISPS-1 and CRISPS-3, the change in waist circumference, but not that in BMI, was associated with the changes in both systolic and diastolic blood pressures (beta=0.087, P=0.015 and beta=0.122, P<0.001 respectively). Conclusions: The increase in prevalence of hypertension might be explained by the increase in central obesity. Our findings further confirm the importance of waist circumference in this population; calculating the BMI alone may give a false sense of security. Acknowledgement: This study was funded by Hong Kong Research Grant Council grants (HKU7229/01M and HKU7626/07M) and the Sun Chieh Yeh Heart Foundation.published_or_final_versio

Association of genetic variants in gene encoding lipocalin-2 with plasma alanine aminotransferase and aspartate aminotransferase

published_or_final_versionThe 16th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 17, abstract no. 1

Estimation of summary protective efficacy using a frailty mixture model for recurrent event time data.

Recurrent event time data are common in experimental and observational studies. The analytic strategy needs to consider three issues: within-subject event dependence, between-subject heterogeneity in event rates, and the possibility of a nonsusceptible fraction. Motivated by the need to estimate the summary protective efficacy from recurrent event time data as seen in many infectious disease clinical trials, we propose a two-part frailty mixture model that simultaneously accommodates all the three issues. In terms of vaccine action models, the proposed model is a combination of the 'all-or-none' and the 'leaky' models, and the summary protective efficacy is a unified measure of the vaccine's twofold effects in completely or partially protecting the vaccinated individuals against the study event. The model parameters of interest are estimated using the expectation-maximization algorithm with their respective variances estimated using Louis's formula for the expectation-maximization algorithm. The summary protective efficacy is estimated by a composite estimand with its variance estimated using the delta method. The performance of the proposed estimation approach is investigated by a simulation study. Data from a trial of malaria prophylaxis conducted in Ghana are reanalyzed

The relationship between glucose metabolism, metabolic syndrome, and bone-specific alkaline phosphatase: A structural equation modeling approach.

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Non-invasive score identifies ultrasonography-diagnosed non-alcoholic fatty liver disease and predicts mortality in the USA

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The relationship between glucose metabolism, metabolic syndrome, and bone-specific alkaline phosphatase: a structural equation modelling approach

PosterINTRODUCTION: Serum alkaline phosphatase plays a role in vascular calcification. It is found in various tissues, whereas bone-specific alkaline phosphatase (BAP) more specifically reflects mineral metabolism. The relationship of serum alkaline phosphatase (total and bone-specific) with diabetes and metabolic syndrome, which are two major risk factors of vascular calcification, is largely unknown. We aimed to investigate the relationships between glucose metabolism, components of metabolic syndrome (MetS), and alkaline …published_or_final_versio