Modular kinetic analysis of the adenine nucleotide translocator-mediated effects of palmitoyl-CoA on the oxidative phosphorylation in isolated rat liver mitochondria

To test whether long-chain fatty acyl-CoA esters link obesity with type 2 diabetes through inhibition of the mitochondrial adenine nucleotide translocator, we applied a system-biology approach, dual modular kinetic analysis, with mitochondrial membrane potential (Deltapsi) and the fraction of matrix ATP as intermediates. We found that 5 mumol/l palmitoyl-CoA inhibited adenine nucleotide translocator, without direct effect on other components of oxidative phosphorylation. Indirect effects depended on how oxidative phosphorylation was regulated. When the electron donor and phosphate acceptor were in excess, and the mitochondrial "work" flux was allowed to vary, palmitoyl-CoA decreased phosphorylation flux by 38% and the fraction of ATP in the medium by 39%. Deltapsi increased by 15 mV, and the fraction of matrix ATP increased by 46%. Palmitoyl-CoA had a stronger effect when the flux through the mitochondrial electron transfer chain was maintained constant: Deltapsi increased by 27 mV, and the fraction of matrix ATP increased 2.6 times. When oxidative phosphorylation flux was kept constant by adjusting the rate using hexokinase, Deltapsi and the fraction of ATP were not affected. Palmitoyl-CoA increased the extramitochondrial AMP concentration significantly. The effects of palmitoyl-CoA in our model system support the proposed mechanism linking obesity and type 2 diabetes through an effect on adenine nucleotide translocator.     

The validity of screening based on spot morning urine samples to detect subjects with microalbuminuria in the general population

BACKGROUND: No study has yet investigated the validity of prescreening by albumin measurements in a spot morning urine sample to identify in the general population subjects with microalbuminuria. We therefore tested the diagnostic performance of urinary albumin concentration (UAC) and albumin-creatinine ratio (ACR), measured in a spot morning urine sample, in predicting a urinary albumin excretion (UAE) > or =30 mg in subsequent 24-hour urines (microalbuminuria). METHODS: Subjects (2527) participating in the PREVEND study, a representative sample from the general population, collected a spot morning urine sample and, on average, 77 days later, two 24-hour urine collections. RESULTS: The ROC curve of UAC in predicting microalbuminuria has an area-under-the-curve of 0.92 with a discriminator value of 11.2 mg/L. Using this cut-off value for UAC, sensitivity in predicting microalbuminuria is 85.0%, and specificity 85.0%. For ACR these values are, respectively: area-under-the-curve 0.93, discriminator value 9.9 mg/g, sensitivity 87.6%, and specificity 87.5%. Sensitivity for UAC in predicting microalbuminuria does not differ significantly from the sensitivity for ACR, whereas the difference between the specificities of UAC and ACR reaches statistical significance, but is numerically very small. In various subgroups characterized by differences in urinary creatinine excretion, the area-under-the-ROC curve, sensitivity, as well as specificity, do not increase relevantly compared to the results in the overall study population. This holds true for ACR as well as UAC. CONCLUSION: The diagnostic performance of measuring UAC in a spot morning urine sample in predicting microalbuminuria in subsequent 24-hour urine collections is satisfactory, and, moreover, comparable to that of measuring ACR. In order to keep the burden and costs involved in population screening for microalbuminuria as low as possible, we therefore propose prescreening by measuring UAC in a spot morning urine sample. Those subjects with a UAC above a certain predefined level (e.g., 11 mg/L) should be asked to collect timed urine samples.     

Targeting of the virulence factor acetohydroxyacid synthase by sulfonylureas results in inhibition of intramacrophagic multiplication of Brucella suis

The acetohydroxyacid synthase (AHAS) of Brucella suis can be effectively targeted by the sulfonylureas chlorimuron ethyl and metsulfuron methyl. Growth in minimal medium was inhibited, and multiplication in human macrophages was totally abolished with 100 microM of sulfonylureas. Metsulfuron methyl-resistant mutants showed reduced viability in macrophages and reduced AHAS activity.     

G-Protein-coupled receptor polymorphisms are associated with asthma in a large German population

RATIONALE: Recently, a new asthma susceptibility gene, GPRA (G-protein-related receptor for asthma), has been identified by positional cloning. Initial association studies in a Finnish and Canadian population suggested an association with asthma and elevated serum IgE levels. OBJECTIVE: In a large, nested case-control study, associations between GPRA polymorphisms, asthma, and serum IgE levels were analyzed. Methods: Using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) technology, 1,872 German children aged 9 to 11 years (including 624 children with asthma and/or bronchial hyperresponsiveness) were genotyped for seven polymorphisms in the GPRA gene. MEASUREMENTS: Hardy-Weinberg equilibrium was assessed, and association studies with single nucleotide polymorphisms (SNPs) and haplotypes were performed. MAIN RESULTS: SNP 546333 increased the risk for asthma (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.04-1.88; p = 0.025) and concomitant asthma and bronchial hyperresponsiveness (BHR; OR, 2.38; 95% CI, 1.22-4.66; p = 0.009). Also, SNP 585883 was associated with asthma (OR, 1.34; 95% CI, 1.04-1.72; p = 0.022) and asthma in combination with BHR (OR, 2.71; 95% CI, 1.45-5.09; p = 0.001). Furthermore, SNP 585883 was associated with elevated serum IgE levels (OR, 1.63; 95% CI, 1.10-2.42; p = 0.015). Haplotype combinations of risk alleles increased the OR for asthma to 1.83 (95% CI, 1.08-3.08; p = 0.024) and for asthma and concomitant BHR to OR 3.51 (95% CI, 1.08-11.37; p = 0.036). CONCLUSIONS: These results indicate that GPRA polymorphisms increase the susceptibility for asthma and BHR, and to a lesser degree for the elevation of serum IgE, in a German population, confirming initial observations in other white populations.     

Patients aged 90 years or older in the intensive care unit

BACKGROUND: Age is an important prognostic factor in patients admitted to intensive care units (ICUs), but it is not as important as illness severity. However, age seems to remain an important independent triage criterion for ICU admission, and 90 years of age seems to represent a psychological barrier for many ICU physicians. The aim of this preliminary study is to compare the management and outcome of patients aged 90 years or older admitted to a respiratory ICU with those of patients aged 70 years or younger. METHODS: In our matched case-control study over a 6-year period, 36 patients aged 90 years or older (case patients) were selected and matched according to sex with 72 controls chosen in the 20- to 69-year age range. The Simplified Acute Physiology Score (SAPS) II was then computed without using age as a variable. RESULTS: Pre-existing comorbidities were significantly less frequent in cases than in controls (5.1% vs 30.5%, p <.01). Compared to controls, cases were more frequently admitted for cardiac failure (22% vs 7%, p <.05) and less frequently for neurological diseases (0% vs 11%, p <.05). The use of advanced life-support measures in the ICU such as mechanical ventilation, central venous or arterial catheterization, and vasoactive and/or inotropic drugs was not significantly different between case patients and controls. This was also the case for ICU mortality and for the mean duration of ICU and hospital stay. Although there was a trend toward a higher hospital mortality among case patients than among controls, it did not reach statistical significance (47% vs 27%, p =.07). CONCLUSION: Our results reinforce the idea that age alone is not a relevant criterion for ICU admission.