Metabolic syndrome traits exhibit genotype-by-environment interaction in relation to socioeconomic status in the Mexican American family heart study.

Background: Socioeconomic Status (SES) is a potent environmental determinant of health. To our knowledge, no assessment of genotype-environment interaction has been conducted to consider the joint effects of socioeconomic status and genetics on risk for metabolic disease. We analyzed data from the Mexican American Family Studies (MAFS) to evaluate the hypothesis that genotype-by-environment interaction (GxE) is an essential determinant of variation in risk factors for metabolic syndrome (MS). Methods: We employed a maximum likelihood estimation of the decomposition of variance components to detect GxE interaction. After excluding individuals with diabetes and individuals on medication for diabetes, hypertension, or dyslipidemia, we analyzed 12 MS risk factors: fasting glucose (FG), fasting insulin (FI), 2-h glucose (2G), 2-h insulin (2I), body mass index (BMI), waist circumference (WC), leptin (LP), high-density lipoprotein-cholesterol (HDL-C), triglycerides (TG), total serum cholesterol (TSC), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Our SES variable used a combined score of Duncan's socioeconomic index and education years. Heterogeneity in the additive genetic variance across the SES continuum and a departure from unity in the genetic correlation coefficient were taken as evidence of GxE interaction. Hypothesis tests were conducted using standard likelihood ratio tests. Results: We found evidence of GxE for fasting glucose, 2-h glucose, 2-h insulin, BMI, and triglycerides. The genetic effects underlying the insulin/glucose metabolism component of MS are upregulated at the lower end of the SES spectrum. We also determined that the household variance for systolic blood pressure decreased with increasing SES. Conclusion: These results show a significant change in the GxE interaction underlying the major components of MS in response to changes in socioeconomic status. Further mRNA sequencing studies will identify genes and canonical gene pathways to support our molecular-level hypotheses.

Genotype-by-socioeconomic status interaction influences heart disease risk scores and carotid artery thickness in Mexican Americans: the predominant role of education in comparison to household income and socioeconomic index.

Background: Socioeconomic status (SES) is a potent environmental determinant of health. To our knowledge, no assessment of genotype-environment interaction has been conducted to consider the joint effects of socioeconomic status and genetics on risk for cardiovascular disease (CVD). We analyzed Mexican American Family Studies (MAFS) data to evaluate the hypothesis that genotype-by-environment interaction (GxE) is an important determinant of variation in CVD risk factors. Methods: We employed a linear mixed model to investigate GxE in Mexican American extended families. We studied two proxies for CVD [Pooled Cohort Equation Risk Scores/Framingham Risk Scores (FRS/PCRS) and carotid artery intima-media thickness (CA-IMT)] in relation to socioeconomic status as determined by Duncan's Socioeconomic Index (SEI), years of education, and household income. Results: We calculated heritability for FRS/PCRS and carotid artery intima-media thickness. There was evidence of GxE due to additive genetic variance heterogeneity and genetic correlation for FRS, PCRS, and CA-IMT measures for education (environment) but not for household income or SEI. Conclusion: The genetic effects underlying CVD are dynamically modulated at the lower end of the SES spectrum. There is a significant change in the genetic architecture underlying the major components of CVD in response to changes in education.

Congenital Heart Disease with Congenital Diaphragmatic Hernia: Surgical Decision Making and Outcomes.

OBJECTIVE: To describe the types of congenital heart disease (CHD) in a congenital diaphragmatic hernia (CDH) cohort in a large volume center and evaluate surgical decision making and outcomes based on complexity of CHD and associated conditions. STUDY DESIGN: A retrospective review of patients with CHD and CDH diagnosed by echocardiogram between 01/01/2005 and 07/31/2021. The cohort was divided into 2 groups based on survival at discharge. RESULTS: Clinically important CHD was diagnosed in 19% (62/326) of CDH patients. There was 90% (18/20) survival in children undergoing surgery for both CHD and CDH as neonates, and 87.5 (22/24) in those undergoing repair initially for CDH alone. A genetic anomaly identified on clinical testing was noted in 16% with no significant association with survival. A higher frequency of other organ system anomalies was noted in nonsurvivors compared with survivors. Nonsurvivors were more likely to have unrepaired CDH (69% vs 0%, P < .001) and unrepaired CHD (88% vs 54%, P < .05), reflecting a decision not to offer surgery. CONCLUSIONS: Survival was excellent in patients who underwent repair of both CHD and CDH. Patients with univentricular physiology have poor survival and this finding should be incorporated into pre and postnatal counseling about eligibility for surgery. In contrast, patients with other complex lesions including transposition of the great arteries have excellent outcomes and survival at 5 years follow-up at a large pediatric and cardiothoracic surgical center.

Non-alcoholic Fatty Liver Disease and Depression: Evidence for Genotype × Environment Interaction in Mexican Americans.

This study examines the impact of G × E interaction effects on non-alcoholic fatty liver disease (NAFLD) among Mexican Americans in the Rio Grande Valley (RGV) of South Texas. We examined potential G × E interaction using variance components models and likelihood-based statistical inference in the phenotypic expression of NAFLD, including hepatic steatosis and hepatic fibrosis (identified using vibration controlled transient elastography and controlled attenuation parameter measured by the FibroScan Device). We screened for depression using the Beck Depression Inventory-II (BDI-II). We identified significant G × E interactions for hepatic fibrosis × BDI-II. These findings provide evidence that genetic factors interact with depression to influence the expression of hepatic fibrosis.

Influence of the Human Lipidome on Epicardial Fat Volume in Mexican American Individuals.

Introduction: Cardiovascular disease (CVD) is the leading cause of mortality worldwide and is the leading cause of death in the US. Lipid dysregulation is a well-known precursor to metabolic diseases, including CVD. There is a growing body of literature that suggests MRI-derived epicardial fat volume, or epicardial adipose tissue (EAT) volume, is linked to the development of coronary artery disease. Interestingly, epicardial fat is also actively involved in lipid and energy homeostasis, with epicardial adipose tissue having a greater capacity for release and uptake of free fatty acids. However, there is a scarcity of knowledge on the influence of plasma lipids on EAT volume. Aim: The focus of this study is on the identification of novel lipidomic species associated with CMRI-derived measures of epicardial fat in Mexican American individuals. Methods: We performed lipidomic profiling on 200 Mexican American individuals. High-throughput mass spectrometry enabled rapid capture of precise lipidomic profiles, providing measures of 799 unique species from circulating plasma samples. Because of our extended pedigree design, we utilized a standard quantitative genetic linear mixed model analysis to determine whether lipids were correlated with EAT by formally testing for association between each lipid species and the CMRI epicardial fat phenotype. Results: After correction for multiple testing using the FDR approach, we identified 135 lipid species showing significant association with epicardial fat. Of those, 131 lipid species were positively correlated with EAT, where increased circulating lipid levels were correlated with increased epicardial fat. Interestingly, the top 10 lipid species associated with an increased epicardial fat volume were from the deoxyceramide (Cer(m)) and triacylglycerol (TG) families. Deoxyceramides are atypical and neurotoxic sphingolipids. Triacylglycerols are an abundant lipid class and comprise the bulk of storage fat in tissues. Pathologically elevated TG and Cer(m) levels are related to CVD risk and, in our study, to EAT volume. Conclusion: Our results indicate that specific lipid abnormalities such as enriched saturated triacylglycerols and the presence of toxic ceramides Cer(m) in plasma of our individuals could precede CVD with increased EAT volume.

The Risk of Incarceration During Nonoperative Management of Incisional Hernias: A Population-based Analysis of 30,998 Patients.

OBJECTIVE: The aim of the study was to quantify the risk of incarceration of incisional hernias. BACKGROUND: Operative repair is the definitive treatment for incisional ventral hernias but is often deferred if the perceived risk of elective operation is elevated secondary to comorbid conditions. The risk of incarceration during nonoperative management (NOM) factors into shared decision making by patient and surgeon; however, the incidence of acute incarceration remains largely unknown. METHODS: A retrospective analysis of adult patients with an International Classification of Diseases, Ninth Revision or Tenth Revision diagnosis of incisional hernia was conducted from 2010 to 2017 in 15 hospitals of a single healthcare system. The primary outcome was incarceration necessitating emergent operation. The secondary outcome was 30-, 90-, and 365-day mortality. Univariate and multivariate analyses were used to determine independent predictors of incarceration. RESULTS: Among 30,998 patients with an incisional hernia (mean age 58.1 ±â€Š15.9 years; 52.7% female), 23,022 (78.1%) underwent NOM of whom 540 (2.3%) experienced incarceration, yielding a 1- and 5-year cumulative incidence of 1.24% and 2.59%, respectively. Independent variables associated with incarceration included: age older than 40 years, female sex, current smoker, body mass index 30 or greater, and a hernia-related inpatient admission. All-cause mortality rates at 30, 90, and 365 days were significantly higher in the incarceration group at 7.2%, 10%, and 14% versus 1.1%, 2.3%, and 5.3% in patients undergoing successful NOM, respectively. CONCLUSIONS: Incarceration is an uncommon complication of NOM but is associated with a significant risk of death. Tailored decision making for elective repair and considering the aforementioned risk factors for incarceration provides an initial step toward mitigating the excess morbidity and mortality of an incarceration event.

Frailty Index in the Colonias on the US-Mexico Border: A Special Report.

Frailty is the age-related decline in well-being. The Frailty index (FI) measures the accumulation of health deficits and reflects biopsychosocial and cultural determinants of well-being. Frailty is measured as a static phenotype or as a Frailty Index comprising a ratio of suffered health deficits and total deficits. We report a Frailty Index calculated from routinely measured clinical variables gathered from residents of two Colonias (neighborhoods) in South Texas. A Colonia is a predominantly Hispanic, economically distressed, unincorporated neighborhood. We analyzed retrospective data from 894 patients that live in two Colonias located on the Texas-Mexico border. We calculated the FI with seven physiological variables, PHQ-9 score, and the 11 domain-specific Duke Profile scores, for a total of 19 possible health deficits. FI against age separately in males (n = 272) and females (n = 622) was regressed. Females had a significantly higher starting frailty, and males had a significantly greater change rate with age. FI against age for Cameron Park Colonia and Indian Hills Colonia was regressed. We calculated a significantly higher starting FI in Indian Hills and a significantly greater change rate in Cameron Park residents. Frailty's contributors are complex, especially in neighborhoods of poverty, immigration, low education level, and high prevalence of chronic disease. We report baseline Frailty Index data from two Colonias in South Texas and the clinical and research implications.

Pseudomonas stutzeri MJL19, a rhizosphere-colonizing bacterium that promotes plant growth under saline stress.

AIMS: The aim of this study was to find and use rhizobacteria able to confer plants advantages to deal with saline conditions. METHODS AND RESULTS: We isolated 24 different bacterial species from the rhizosphere of halophyte plants growing in Santiago del Estero, Argentina salt flat. Four strains were selected upon their ability to grow in salinity and their biochemical traits associated with plant growth promotion. Next, we tested the adhesion on soybean seeds surface and root colonization with the four selected isolates. Isolate 19 stood out from the rest and was selected for further experiments. This strain showed positive chemotaxis towards soybean root exudates and a remarkable ability to form biofilm both in vitro conditions and on soybean roots. Interestingly, this trait was enhanced in high saline conditions, indicating the extremely adapted nature of the bacterium to high salinity. In addition, this strain positively impacted on seed germination, plant growth and general plant health status also under saline stress. CONCLUSIONS: A bacterium isolate with outstanding ability to promote seed germination and plant growth under saline conditions was found. SIGNIFICANCE AND IMPACT OF THE STUDY: The experimental approach allowed us to find a suitable bacterial candidate for a biofertilizer intended to alleviate saline stress on crops. This would allow the use of soil now considered inadequate for agriculture and thus prevent further advancement of agriculture frontiers into areas of environmental value.

Is True Whole-Body 18F-FDG PET/CT Required in Pediatric Lymphoma? An IAEA Multicenter Prospective Study.

Guidelines recommend true whole-body 18F-FDG PET/CT scans from vertex to toes in pediatric lymphoma patients, although this suggestion has not been validated in large clinical trials. The objective of the study was to evaluate the incidence and clinical impact of lesions outside the "eyes to thighs" regular field of view (R-FOV) in 18F-FDG PET/CT staging (sPET) and interim (iPET) scans in pediatric lymphoma patients. Methods: True whole-body sPET and iPET scans were prospectively obtained in pediatric lymphoma patients (11 worldwide centers). Expert panel central review of sPET and iPET scans were evaluated for lymphoma lesions outside the R-FOV and clinical relevance of these findings. Results: A total of 610 scans were obtained in 305 patients. The sPET scans did not show lesions outside the R-FOV in 91.8% of the patients, whereas in 8.2% patients the sPET scans demonstrated lesions also outside the R-FOV (soft tissue, bone, bone marrow, and skin); however, the presence of these lesions did not change the clinical stage of any patient and did not affect treatment decision. Among the 305 iPET scans, there were no new positive 18F-FDG-avid lesions outside the R-FOV, when compared with their paired sPET scans. A single lesion outside the R-FOV on iPET occurred in 1 patient (0.3%), with the primary lesion diagnosed in the femur on sPET that persisted on iPET. Conclusion: The identification of additional lesions outside the R-FOV (eyes to thighs) using 18F-FDG PET/CT has no impact in the definition of the clinical stage of disease and minimal impact in the treatment definition of patients with pediatric lymphoma. As so, R-FOV for both sPET and iPET scans could be performed.

Genetic and environmental (physical fitness and sedentary activity) interaction effects on cardiometabolic risk factors in Mexican American children and adolescents.

Knowledge on genetic and environmental (G × E) interaction effects on cardiometabolic risk factors (CMRFs) in children is limited.  The purpose of this study was to examine the impact of G × E interaction effects on CMRFs in Mexican American (MA) children (n = 617, ages 6-17 years). The environments examined were sedentary activity (SA), assessed by recalls from "yesterday" (SAy) and "usually" (SAu) and physical fitness (PF) assessed by Harvard PF scores (HPFS). CMRF data included body mass index (BMI), waist circumference (WC), fat mass (FM), fasting insulin (FI), homeostasis model of assessment-insulin resistance (HOMA-IR), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), systolic (SBP) and diastolic (DBP) blood pressure, and number of metabolic syndrome components (MSC). We examined potential G × E interaction in the phenotypic expression of CMRFs using variance component models and likelihood-based statistical inference. Significant G × SA interactions were identified for six CMRFs: BMI, WC, FI, HOMA-IR, MSC, and HDL, and significant G × HPFS interactions were observed for four CMRFs: BMI, WC, FM, and HOMA-IR. However, after correcting for multiple hypothesis testing, only WC × SAy, FM × SAy, and FI × SAu interactions became marginally significant. After correcting for multiple testing, most of CMRFs exhibited significant G × E interactions (Reduced G × E model vs. Constrained model). These findings provide evidence that genetic factors interact with SA and PF to influence variation in CMRFs, and underscore the need for better understanding of these relationships to develop strategies and interventions to effectively reduce or prevent cardiometabolic risk in children.

Pseudomonas protegens CS1 from the lemon phyllosphere as a candidate for citrus canker biocontrol agent.

Citrus canker is a worldwide-distributed disease caused by Xanthomonas citri subsp. citri. One of the most used strategies to control the disease is centred on copper-based compounds that cause environmental problems. Therefore, it is of interest to develop new strategies to manage the disease. Previously, we reported the ability of the siderophore pyochelin, produced by the opportunistic human pathogen Pseudomonas aeruginosa, to inhibit in vitro several bacterial species, including X. citri subsp. citri. The action mechanism, addressed with the model bacterium Escherichia coli, was connected to the generation of reactive oxygen species (ROS). This work aimed to find a non-pathogenic strain from the lemon phyllosphere that would produce pyochelin and therefore serve in canker biocontrol. An isolate that retained its capacity to colonise the lemon phyllosphere and inhibit X. citri subsp. citri was selected and characterised as Pseudomonas protegens CS1. From a liquid culture of this strain, the active compound was purified and identified as the pyochelin enantiomer, enantio-pyochelin. Using the producing strain and the pure compound, both in vitro and in vivo, we determined that the action mechanism of X. citri subsp. citri inhibition also involved the generation of ROS. Finally, the potential application of P. protegens CS1 was evaluated by spraying the bacterium in a model that mimics the natural X. citri subsp. citri infection. The ability of P. protegens CS1 to reduce canker formation makes this strain an interesting candidate as a biocontrol agent.

A prospective and retrospective analysis of smoking behavior changes in ever smokers with high risk for lung cancer from New Mexico and Pennsylvania.

Cigarette smoking is the leading preventable cause of death worldwide. The aim of this study is to conduct a prospective and retrospective analysis of smoking behavior changes in the Lovelace Smokers Cohort (LSC) and the Pittsburgh Lung Screening Study cohort (PLuSS). Area under the curve (AUC) for risk models predicting relapse based on demographic, smoking, and relevant clinical variables was 0.93 and 0.79 in LSC and PLuSS, respectively. The models for making a quit attempt had limited prediction ability in both cohorts (AUC≤0.62). We identified an ethnic disparity in adverse smoking behavior change that Hispanic smokers were less likely to make a quit attempt and were more likely to relapse after a quit attempt compared to non-Hispanic Whites. SNPs at 15q25 and 11p14 loci were associated with risk for smoking relapse in the LSC. Rs6495308 at 15q25 has a large difference in minor allele frequency between non-Hispanic Whites and Hispanics (0.46 versus 0.23, P<0.0001) and was associated with risk for ever relapse at same magnitude between the two ethnic groups (OR=1.36, 95% CI=1.10 to 1.67 versus 1.59, 95% CI=1.00 to 2.53, P=0.81). In summary, the risk prediction model established in LSC and PLuSS provided an excellent to outstanding distinguishing for abstainers who will or will not relapse. The ethnic disparity in adverse smoking behavior between Hispanics and non-Hispanic Whites may be at least partially explained by the sequence variants at 15q25 locus that contains multiple nicotine acetylcholine receptors.

The Efficacy of Multiparametric Magnetic Resonance Imaging and Magnetic Resonance Imaging Targeted Biopsy in Risk Classification for Patients with Prostate Cancer on Active Surveillance.

PURPOSE: We determined whether multiparametric magnetic resonance imaging targeted biopsies may replace systematic biopsies to detect higher grade prostate cancer (Gleason score 7 or greater) and whether biopsy may be avoided based on multiparametric magnetic resonance imaging among men with Gleason 3+3 prostate cancer on active surveillance. MATERIALS AND METHODS: We identified men with previously diagnosed Gleason score 3+3 prostate cancer on active surveillance who underwent multiparametric magnetic resonance imaging and a followup prostate biopsy. Suspicion for higher grade cancer was scored on a standardized 5-point scale. All patients underwent a systematic biopsy. Patients with multiparametric magnetic resonance imaging regions of interest also underwent magnetic resonance imaging targeted biopsy. The detection rate of higher grade cancer was estimated for different multiparametric magnetic resonance imaging scores with the 3 biopsy strategies of systematic, magnetic resonance imaging targeted and combined. RESULTS: Of 206 consecutive men on active surveillance 135 (66%) had a multiparametric magnetic resonance imaging region of interest. Overall, higher grade cancer was detected in 72 (35%) men. A higher multiparametric magnetic resonance imaging score was associated with an increased probability of detecting higher grade cancer (Wilcoxon-type trend test p <0.0001). Magnetic resonance imaging targeted biopsy detected higher grade cancer in 23% of men. Magnetic resonance imaging targeted biopsy alone missed higher grade cancers in 17%, 12% and 10% of patients with multiparametric magnetic resonance imaging scores of 3, 4 and 5, respectively. CONCLUSIONS: Magnetic resonance imaging targeted biopsies increased the detection of higher grade cancer among men on active surveillance compared to systematic biopsy alone. However, a clinically relevant proportion of higher grade cancer was detected using only systematic biopsy. Despite the improved detection of disease progression using magnetic resonance imaging targeted biopsy, systematic biopsy cannot be excluded as part of surveillance for men with low risk prostate cancer.

Bovine semen quality control in artificial insemination centers

Quality control (QC) is a fundamental area of management for semen production centers (SPCs) supplying bovine semen to breeders and producers. Semen production centers are moving away from subjective semen assessment, that is largely uncorrelated to field fertility, to objective semen analyses that incorporate computer assisted sperm analysis (CASA) and flow cytometry. A multiparametric approach to semen analysis using a combination of CASA and fl ow cytometry can provide SPCs with the highest QC for all semen production. In this paper we review probes used for labelling spermatozoa for viability, acrosomal integrity, mitochondrial activity, DNA integrity and calcium release. Limitations of CASA and flow cytometry when analyzing spermatozoa, especially frozen-thawed samples, are discussed. Finally, we described how a multiparametric approach using CASA and flow cytometry could be applied in SPCs to establish QC of production before the release of the product in the field.

Bovine semen quality control in artificial insemination centers

Quality control (QC) is a fundamental area of management for semen production centers (SPCs) supplying bovine semen to breeders and producers. Semen production centers are moving away from subjective semen assessment, that is largely uncorrelated to field fertility, to objective semen analyses that incorporate computer assisted sperm analysis (CASA) and flow cytometry. A multiparametric approach to semen analysis using a combination of CASA and fl ow cytometry can provide SPCs with the highest QC for all semen production. In this paper we review probes used for labelling spermatozoa for viability, acrosomal integrity, mitochondrial activity, DNA integrity and calcium release. Limitations of CASA and flow cytometry when analyzing spermatozoa, especially frozen-thawed samples, are discussed. Finally, we described how a multiparametric approach using CASA and flow cytometry could be applied in SPCs to establish QC of production before the release of the product in the field.(AU)

Genotype by diabetes interaction effects on the detection of linkage of glomerular filtration rate to a region on chromosome 2q in Mexican Americans.

OBJECTIVE: Glomerular filtration rate (GFR) is used to assess the progression of renal disease. We performed linkage analysis to localize genes that influence GFR using estimated GFR data from the San Antonio Family Diabetes/Gallbladder Study. We also examined the effect of genotype by diabetes interaction (G x DM) on the detection of linkage to address whether genetic effects on GFR differ in diabetic and nondiabetic subjects. RESEARCH DESIGN AND METHODS: GFR (N = 453) was estimated using the recently recalculated Cockcroft-Gault (GFR-CGc) and the simplified Modification of Diet in Renal Disease (GFR-4VMDRD) formulae. Both estimates of GFR exhibited significant heritabilities, but only GFR-CGc showed significant G x DM interaction. We therefore performed multipoint linkage analyses on both GFR measures using models that did not include G x DM interaction effects (Model 1) and that included G x DM interaction effects (Model 2, in the case of GFR-CGc). RESULTS: The strongest evidence for linkage (Model 1) of both GFR-CGc (logarithm of odds [LOD] 2.9) and GFR-4VMDRD (LOD 2.6) occurred between markers D9S922 and D9S1120 on chromosome 9q. However, using Model 2, the strongest evidence for linkage of GFR-CGc on chromosome 2q was found near marker D2S427 (corrected LOD score [LOD(C)] 3.3) compared with the LOD score of 2.7 based on Model 1. Potential linkages (LOD or LOD(C) >or=1.2) were found only for GFR-CGc on chromosomes 3p, 3q, 4p, 8q, 11q, and 14q. CONCLUSIONS: We found a major locus on chromosome 2q that differentially influences GFR in diabetic and nondiabetic environments in the Mexican-American population.

Genetic connectivity in the Florida reef system: comparative phylogeography of commensal invertebrates with contrasting reproductive strategies.

Effective spatial management of coral reefs including design of marine protected areas requires an understanding of interpopulation genetic connectivity. We assessed gene flow along 355 km of the Florida reef system and between Florida and Belize in three commensal invertebrates occupying the same host sponge (Callyspongia vaginalis) but displaying contrasting reproductive dispersal strategies: the broadcast-spawning brittle star Ophiothrix lineata and two brooding amphipods Leucothoe kensleyi and Leucothoe ashleyae. Multiple analytical approaches to sequence variation in the mitochondrial COI gene demonstrated a high degree of overall connectivity for all three species along the Florida reef system. Ophiothrix lineata showed significant genetic structuring between Florida and Belize, and a pattern of isolation by distance but no significant genetic structuring along the Florida coastline. Bayesian estimates of migration detected a strong southerly dispersal bias for O. lineata along the Florida reef system, contrary to the general assumption of northerly gene flow in this region based on the direction of the Florida Current. Both amphipods, despite direct development, also showed high gene flow along the Florida reef system. Multiple inferences of long-distance dispersal from a nested clade analysis support the hypothesis that amphipod transport, possibly in detached sponge fragments, could generate the high levels of overall gene flow observed. However, this transport mechanism appears much less effective across deep water as connectivity between Florida and Belize (1072 km) is highly restricted.

A technique for cutting brittle undisturbed lateritic soil block samples.

This note describes a technique for cutting undisturbed brittle block samples into smaller specimens for further geotechnical testing. This technique revealed very useful in dealing with collapsible soils, where the sampling is recommended to be done with block soil samples. A further use of this technique as an efficient way for sampling collapsible soils is proposed.

Rat renal prorenin concentration in experimental hypertension.

The amount of renal prorenin in models of hypertension in rats was studied by using a novel enzyme (PreR-Co). Ten microgrames of PreR-Co promoted a complete conversion of inactive renin, and during the first 15-min incubation the reaction was under initial velocity conditions. The enzyme-substrate reaction obeyed Michaelis-Menten kinetics, with a Vmax of 0.97 x 10(-5) pmol Ang I/min and a Km of 5.03 x 10(-5) pmol prorenin. The difference between the total renin concentration (TRC) and active renin concentration (ARC) in the normal rat kidney (356.4 +/- 20.6 and 105.3 +/- 7.6 ng Ang I/mg tissue/h respectively), indicated that inactive renin comprised 70% of TRC. In the aortic coarctation model, inactive renin comprised 68 % of TRC in the right kidney and no or very little prorenin was found in the left kidney. In the Goldblatt 2-kidney, 1-clip rats, the right kidney prorenin comprised 61% of the TRC and 54% in the clamped left kidney. After DOCA-Salt treatment prorenin was almost absent in the rat kidneys. In conclusion, we have developed an easy and sensitive method to measure inactive renin in the kidney that may be useful to study the biochemical events of renin maturation in physiological and pathological states.

Rat renal and plasma prorenin are activated in vitro by different mechanisms.

The aim of the present study was to purify and identify a plasma protein fraction (PreR-Co) involved in renal prorenin activation and to explore its capacity to process plasma prorenin. PreR-Co was obtained from plasma as a single electrophoretic band by (NH(4))(2)SO(4) precipitation, Sephacryl S-200 HR gel filtration, anti-rat albumin immunoaffinity, and ion-exchange chromatography. The amidase, esterase, and kallikrein activities of PreR-Co were studied, as was its N-terminal amino acid sequence. Rat kidney extract or plasma (normal or previously treated with acid to pH 2.8) were incubated with PreR-Co for 15 minutes at 37 degrees C. Renin concentration was measured by incubation with homologous angiotensinogen. The same protocol was repeated with samples activated by trypsin. The N-terminal amino acid sequence was IIGGSMDAKGSFP, which had a homology of 90% with the beta-chain of haptoglobin, 69% with serine-proteases, and 65% with kallikreins. The renin concentration in rat kidney extract was 34+/-4 ng of angiotensin I (Ang I). mg of tissue(-1). h(-1). After PreR-Co or trypsin treatments, renin concentrations were 211+/-7 and 110+/-11 ng of Ang I. mg of tissue(-1). h(-1), respectively. The plasma renin concentration in normal plasma was 67.6+/-13.3 ng of Ang I. mL(-1). h(-1), and no significant difference was observed after PreR-Co treatment. However, a significant increase (202.8+/-7.8 ng of Ang I. mL(-1). h(-1); P<0.01) was found after trypsin treatment. The isolated PreR-Co acts on renal prorenin but not on plasma prorenin. These results suggest that active renin is processed in the kidney by a circulating enzyme that may have a role in the regulation of circulating renin.