Cattle tick Boophilus microplus salivary gland contains a thiol-activated metalloendopeptidase displaying kininase activity

This work reports on the characterization of a metalloendopeptidase kininase present in Boophilus microplus salivary glands. Using the guinea pig ileum assay, salivary gland whole extracts (SGE) were found to have a potent kininase activity. Ion-exchange chromatography separated two kininase activities from SGE. The major enzymatic component, eluted at lower ionic strength, was named BooKase (Boophilus Kininase). Analysis of the hydrolysis products by capillary electrophoresis identified Phe5-Ser6 as the only hydrolyzable peptide bond in bradykinin after BooKase treatment. This is the same specificity as the mammalian thimet oligoendopeptidase (EC 3.4.24.15). Like this enzyme, BooKase is also a metallo-peptidase (requires Mn2+) and is activated by-SH protecting reagents. In addition, BooKase was partially inhibited by cFP-AAF-pAB, a specific inhibitor of thimet oligopeptidase. Contrary to other kininases, BooKase had no activity upon angiontensin I. Our results show that BooKase behaves as a typical peptidase with kinase activity.     

Association between different growth curve definitions of overweight and obesity and cardiometabolic risk in children

Background:

Overweight and obesity in young people are assessed by comparing body mass index (BMI) with a reference population. However, two widely used reference standards, the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) growth curves, have different definitions of overweight and obesity, thus affecting estimates of prevalence. We compared the associations between overweight and obesity as defined by each of these curves and the presence of cardiometabolic risk factors.

Methods:

We obtained data from a population-representative study involving 2466 boys and girls aged 9, 13 and 16 years in Quebec, Canada. We calculated BMI percentiles using the CDC and WHO growth curves and compared their abilities to detect unfavourable levels of fasting lipids, glucose and insulin, and systolic and diastolic blood pressure using receiver operating characteristic curves, sensitivity, specificity and kappa coefficients.

Results:

The z scores for BMI using the WHO growth curves were higher than those using the CDC growth curves (0.35–0.43 v. 0.12–0.28, p < 0.001 for all comparisons). The WHO and CDC growth curves generated virtually identical receiver operating characteristic curves for individual or combined cardiometabolic risk factors. The definitions of overweight and obesity had low sensitivities but adequate specificities for cardiometabolic risk. Obesity as defined by the WHO or CDC growth curves discriminated cardiometabolic risk similarly, but overweight as defined by the WHO curves had marginally higher sensitivities (by 0.6%–8.6%) and lower specificities (by 2.6%–4.2%) than the CDC curves.

Interpretation:

The WHO growth curves show no significant discriminatory advantage over the CDC growth curves in detecting cardiometabolic abnormalities in children aged 9–16 years.Pediatric obesity is associated with dyslipidemia, insulin resistance and elevated blood pressure.^1–6 Thus, accurately identifying children with obesity is crucial for clinical management and public health surveillance.Lipid screening is recommended for young people who are overweight,^7,8 but studies show that estimates of the prevalence of overweight and obesity are 1%–7% lower using the growth curves of the Centers for Disease Control and Prevention (CDC) versus those of the World Health Organization (WHO).^9–11 Although the CDC and WHO definitions of overweight and obesity both use approximations of overweight and obese values of body mass index (BMI) when children reach 19 years of age, the CDC growth curves use data from more recent samples of young people.^12,13 Given the recent rise in the prevalence of obesity among young people, using a heavier reference population may lead to fewer children being identified as overweight and obese, and an identical BMI value may not trigger a clinical investigation.⁷ The Canadian Paediatric Society, in collaboration with the College of Family Physicians of Canada, Dietitians of Canada and Community Health Nurses of Canada, recently recommended that physicians switch from the CDC to the WHO growth curves for monitoring growth for Canadian children aged 5–19 years.¹⁴ This is a major change for health providers caring for the estimated 8 million children in Canada.¹⁵Understanding how using the different growth curves affects the identification of adverse cardiometabolic risk profiles is essential for the appropriate management of overweight and obesity among young people. Thus, our objectives were to assess whether the association between BMI percentiles and cardiometabolic risk differs between the definitions of overweight and obesity based on the WHO and CDC growth curves, and to compare the sensitivity and specificity of these definitions in detecting cardiometabolic risk.     

The ABC transporters in Candidatus Liberibacter asiaticus

Candidatus Liberibacter asiaticus (Ca. L. asiaticus) is a Gram‐negative bacterium and the pathogen of Citrus Greening disease (Huanglongbing, HLB). As a parasitic bacterium, Ca. L. asiaticus harbors ABC transporters that play important roles in exchanging chemical compounds between Ca. L. asiaticus and its host. Here, we analyzed all the ABC transporter‐related proteins in Ca. L. asiaticus. We identified 14 ABC transporter systems and predicted their structures and substrate specificities. In‐depth sequence and structure analysis including multiple sequence alignment, phylogenetic tree reconstruction, and structure comparison further support their function predictions. Our study shows that this bacterium could use these ABC transporters to import metabolites (amino acids and phosphates) and enzyme cofactors (choline, thiamine, iron, manganese, and zinc), resist to organic solvent, heavy metal, and lipid‐like drugs, maintain the composition of the outer membrane (OM), and secrete virulence factors. Although the features of most ABC systems could be deduced from the abundant experimental data on their orthologs, we reported several novel observations within ABC system proteins. Moreover, we identified seven nontransport ABC systems that are likely involved in virulence gene expression regulation, transposon excision regulation, and DNA repair. Our analysis reveals several candidates for further studies to understand and control the disease, including the type I virulence factor secretion system and its substrate that are likely related to Ca. L. asiaticus pathogenicity and the ABC transporter systems responsible for bacterial OM biosynthesis that are good drug targets. Proteins 2012. © 2012 Wiley Periodicals, Inc.     

Flavonoid-rich apples and nitrate-rich spinach augment nitric oxide status and improve endothelial function in healthy men and women: a randomized controlled trial

Flavonoids and nitrates in fruits and vegetables may protect against cardiovascular disease. Dietary flavonoids and nitrates can augment nitric oxide status via distinct pathways, which may improve endothelial function and lower blood pressure. Recent studies suggest that the combination of flavonoids and nitrates can enhance nitric oxide production in the stomach. Their combined effect in the circulation is unclear. Here, our objective was to investigate the independent and additive effects of flavonoid-rich apples and nitrate-rich spinach on nitric oxide status, endothelial function, and blood pressure. A randomized, controlled, crossover trial with healthy men and women (n=30) was conducted. The acute effects of four energy-matched treatments (control, apple, spinach, and apple+spinach), administered in random order, were compared. Measurements included plasma nitric oxide status, assessed by measuring S-nitrosothiols+other nitrosylated species (RXNO) and nitrite, blood pressure, and endothelial function, measured as flow-mediated dilatation of the brachial artery. Results are means and 95% CI. Relative to control, all treatments resulted in higher RXNO (control, 33 nmol/L, 26, 42; apple, 51 nmol/L, 40, 65; spinach, 86 nmol/L, 68, 110; apple+spinach, 69 nmol/L, 54, 88; P<0.01) and higher nitrite (control, 35 nmol/L, 27, 46; apple, 69 nmol/L, 53, 90; spinach, 99 nmol/L, 76, 129; apple+spinach, 80 nmol/L, 61, 104; P<0.01). Compared to control, all treatments resulted in higher flow-mediated dilatation (P<0.05) and lower pulse pressure (P<0.05), and apple and spinach resulted in lower systolic blood pressure (P<0.05). No significant effect was observed on diastolic blood pressure. The combination of apple and spinach did not result in additive effects on nitric oxide status, endothelial function, or blood pressure. In conclusion, flavonoid-rich apples and nitrate-rich spinach can independently augment nitric oxide status, enhance endothelial function, and lower blood pressure acutely, outcomes that may benefit cardiovascular health.     

Characterization and Control of the Microbial Community Affiliated with Copper or Aluminum Heat Exchangers of HVAC Systems

Microbial growth in heating ventilation and air-conditioning (HVAC) systems with the subsequent contamination of indoor air is of increasing concern. Microbes and the subsequent biofilms grow easily within heat exchangers. A comparative study where heat exchangers fabricated from antimicrobial copper were evaluated for their ability to limit microbial growth was conducted using a full-scale HVAC system under conditions of normal flow rates using single-pass outside air. Resident bacterial and fungal populations were quantitatively assessed by removing triplicate sets of coupons from each exchanger commencing the fourth week after their installation for the next 30 weeks. The intrinsic biofilm associated with each coupon was extracted and characterized using selective and differential media. The predominant organisms isolated from aluminum exchangers were species of Methylobacterium of which at least three colony morphologies and 11 distinct PFGE patterns we found; of the few bacteria isolated from the copper exchangers, the majority were species of Bacillus. The concentrations and type of bacteria recovered from the control, aluminum, exchangers were found to be dependent on the type of plating media used and were 11,411-47,257 CFU cm(-2) per coupon surface. The concentration of fungi was found to average 378 CFU cm(-2). Significantly lower concentrations of bacteria, 3 CFU cm(-2), and fungi, 1 CFU cm(-2), were recovered from copper exchangers regardless of the plating media used. Commonly used aluminum heat exchangers developed stable, mixed, bacterial/fungal biofilms in excess of 47,000 organisms per cm(2) within 4 weeks of operation, whereas the antimicrobial properties of metallic copper were able to limit the microbial load affiliated with the copper heat exchangers to levels 99.97 % lower during the same time period.     

Vascular function in rats with adenine-induced chronic renal failure

The aim of the present study was to characterize the function of resistance arteries, and the aorta, in rats with adenine-induced chronic renal failure (A-CRF). Sprague-Dawley rats were randomized to chow with or without adenine supplementation. After 6-10 wk, mesenteric arteries and thoracic aortas were analyzed ex vivo by wire myography. Plasma creatinine concentrations were elevated twofold at 2 wk, and eight-fold at the time of death in A-CRF animals. Ambulatory systolic and diastolic blood pressures measured by radiotelemetry were significantly elevated in A-CRF animals from week 3 and onward. At death, A-CRF animals had anemia, hyperphosphatemia, hyperparathyroidism, and elevated plasma levels of asymmetric dimethylarginine and oxidative stress markers. There were no significant differences between groups in the sensitivity, or maximal response, to ACh, sodium nitroprusside (SNP), norepinephrine, or phenylephrine in either mesenteric arteries or aortas. However, in A-CRF animals, the rate of aortic relaxation was significantly reduced following washout of KCl (both in intact and endothelium-denuded aorta) and in response to ACh and SNP. Also the rate of contraction in response to KCl was significantly reduced in A-CRF animals both in mesenteric arteries and aortas. The media of A-CRF aortas was thickened and showed focal areas of fragmented elastic lamellae and disorganized smooth muscle cells. No vascular calcifications could be detected. These results indicate that severe renal failure for a duration of less than 10 wk in this model primarily affects the aorta and mainly slows the rate of relaxation.     

Bilateral Common Carotid Artery Ligation Transiently Changes Brain Lipid Metabolism in Rats

Brain lipid metabolism was studied in rats following permanent bilateral common carotid artery ligation (BCCL), a model for chronic cerebral hypoperfusion. Unesterified (free) fatty acids (uFA) and acyl-CoA concentrations were measured 6 h, 24 h, and 7 days after BCCL or sham surgery, in high energy-microwaved brain. In BCCL compared to sham rats, cytosolic phospholipase A(2) (cPLA(2)) immunoreactivity in piriform cortex, and concentrations of total uFA and arachidonoyl-CoA, an intermediate for arachidonic acid reincorporation into phospholipids, were increased only at 6 h. At 24 h, immunoreactivity for secretory phospholipase A(2) (sPLA(2)), which may regulate blood flow, was increased near cortical and hippocampal blood vessels. BCCL did not affect levels of brain IB(4)+ microglia, glial fibrillary acidic protein (GFAP)+ astrocytes, cyclooxygenase-2 (COX-2) immunoreactivity at any time, but increased cPLA(2) immunoreactivity in one region at 6 h. Thus, BCCL affected brain lipid metabolism transiently, likely because of compensatory sPLA(2)-mediated vasodilation, without producing evidence of neuroinflammation.