Including Distorted Specimens in Allometric Studies: Linear Mixed Models Account for Deformation.

Allometry-patterns of relative change in body parts-is a staple for examining how clades exhibit scaling patterns representative of evolutionary constraint on phenotype, or quantifying patterns of ontogenetic growth within a species. Reconstructing allometries from ontogenetic series is one of the few methods available to reconstruct growth in fossil specimens. However, many fossil specimens are deformed (twisted, flattened, and displaced bones) during fossilization, changing their original morphology in unpredictable and sometimes undecipherable ways. To mitigate against post burial changes, paleontologists typically remove clearly distorted measurements from analyses. However, this can potentially remove evidence of individual variation and limits the number of samples amenable to study, which can negatively impact allometric reconstructions. Ordinary least squares (OLS) regression and major axis regression are common methods for estimating allometry, but they assume constant levels of residual variation across specimens, which is unlikely to be true when including both distorted and undistorted specimens. Alternatively, a generalized linear mixed model (GLMM) can attribute additional variation in a model (e.g., fixed or random effects). We performed a simulation study based on an empirical analysis of the extinct cynodont, Exaeretodon argentinus, to test the efficacy of a GLMM on allometric data. We found that GLMMs estimate the allometry using a full dataset better than simply using only non-distorted data. We apply our approach on two empirical datasets, cranial measurements of actual specimens of E. argentinus (n = 16) and femoral measurements of the dinosaur Tawa hallae (n = 26). Taken together, our study suggests that a GLMM is better able to reconstruct patterns of allometry over an OLS in datasets comprised of extinct forms and should be standard protocol for anyone using distorted specimens.

Alometria­el estudio de patrónes midiendo los cambios de proporciónes entre diferentes partes del cuerpo­es un método popularmente usado para estudiar como clados exhiben patrónes fenotípicos que representan restricciónes evolutivas, o para cuantificar patrónes de ontogenia entre una especie. Reconstruyendo alometrias para series ontogeneticas es uno de los pocos métodos disponibles para reconstruir el crecimiento de especies fósiles. Sin embargo, fósiles sufren de deformaciónes tafonomicas que alteran la morfología original y algunas veces en maneras no deseadas. Para mitigar estas alteraciones tafonomicas, paleontólogos excluyen mediciones alteradas de sus análisis. Desafortunadamente, esto limita el numero de muestras y potencialmente elimina evidencia de variación individual, impactando reconstrucciones alometricas. Mínimos Cuadrados Ordinarios (MCO) es un método frecuentemente usado para estimar alometria, pero asume niveles constantes de varición entre especímenes; esto es improbable cuando uno incluye especímenes deformados y especímenes indeformables. Alternativamente, Modelos Lineales Generalizados Mixtos (MLGM) pueden atribuir variciónes adicionales en un modelo. Nosotros corrimos simulaciones basadas en análisis empíricos del cinodonte extinto, Exaeretodon argentinus, para determinar la eficacia de MLGM con datos alometricos. Nosotros descubrimos que MLGM estima la alometria usando un conjunto de datos completos, en lugar de solo usar datos distorsionados. Aplicamos este método en dos conjuntos de datos empíricos: medidas craneales de especímenes de E. argentinus (n = 16) y medidas femorales del dinosaurio Tawa hallae (n = 26). Nuestros estudios indican que MLGM puede reconstruir mejor los patrónes de alometria sobre MCO con conjuntos de datos que incluyen especímenes extintos, y debería ser el protocolo estándar cuándo se usan especímenes que están deformados.

Does free nicotine replacement improve smoking cessation rates in cancer patients?

Background: Cigarette smoking is carcinogenic and has been linked to inferior treatment outcomes and complication rates in cancer patients. Here, we report the results of an 18-month pilot smoking cessation program that provided free nicotine replacement therapy (nrt). Methods: In January 2017, the smoking cessation program at our institution began offering free nrt for actively cigarette-smoking patients with cancer. The cost of 4 weeks of nrt was covered by the program, and follow-up was provided by smoking cessation champions. Results: From January 2017 to June 2018, 8095 patients with cancer were screened for cigarette use, of whom 1135 self-identified as current or recent smokers. Of those 1135 patients, 117 enrolled in the program and accepted a prescription for nrt. The rates of patient referral and patients attending a referral appointment were significantly higher in 2018-2018 than they had been in 2015-2016 (100% vs. 80.3%, p < 0.001, and 27.6% vs. 11.3%, p < 0.001, respectively). Median follow-up was 9.0 months (25%-75% interquartile range: 5.7-11.6 months). Of the patients who accepted nrt and who also had complete data (n = 71), 25 (35.2%) reported complete smoking cessation, and 32 (45.1%) reported only decreased cigarette smoking. On univariable analysis, no factors were significantly predictive of smoking cessation, although initial cigarette use (>10 vs. ≤10 initial cigarettes) was significantly predictive of smoking reduction (odds ratio: 5.04; 95% confidence interval: 1.46 to 17.45; p = 0.011). Conclusions: This pilot study of free nrt demonstrated rates of referral and acceptance of nrt that were improved compared with historical rates, and most referred patients either decreased their use of cigarettes or quit entirely.

Expressed Breast Milk as a Predictor of Neonatal Yeast Colonization in an Intensive Care Setting.

BACKGROUND: Yeast colonization is a predictor for invasive infection in neonates. Candida albicans and Candida parapsilosis are leading causes of invasive fungal infection (IFI) in this population. This study examines maternal breast milk as a predictor of colonization of infants with yeast. METHODS: Inclusion criteria were admission longer than 72 hours to the neonatal intensive care unit and parental consent. Cultures of expressed breast milk, when available, and swabs from oral, rectal, and inguinal sites were obtained weekly for 12 weeks, or until discharge, transfer, or death. Cultures were analyzed using standard laboratory methods. Clinical information was extracted from medical records. RESULTS: One hundred thirty infants were enrolled from February 2011 to November 2012. Cultures were obtained in 129 patients. The median (interquartile range [IQR]) gestational age was 34.4 weeks (33.1-37.1 weeks). The median (IQR) birth weight was 2157.5 g (1740-3060 g). No infants developed IFIs. Twenty-nine (22%) infants were colonized with yeast. Potential correlates for colonization in univariate analysis included exposure to antenatal steroids, postnatal antibiotics, and receipt of breast milk containing yeast. Potential correlates that remained after multivariable logistic regression included exposure to antenatal steroids and receipt of breast milk containing yeast. In cases in which yeast was recovered from an individual infant and from the breast milk received by that infant, there was only 30% concordance between yeast species. DISCUSSION: Recovery of yeast from breast milk is associated with colonization with yeast in the neonate. Because Candida transmission via breast milk had a 30% concordance, breast milk is only one of several ways colonization occurs. Further study is needed on mechanisms of colonization.

Efficacy of an amlodipine/olmesartan treatment algorithm in patients with or without type 2 diabetes and hypertension (a secondary analysis of the BP-CRUSH study).

A prespecified subgroup analysis of an open-label, multicenter, single-arm, dose-titration study is presented. The efficacy and safety of 20-week treatment with an amlodipine (AML)/olmesartan medoxomil (OM)±hydrochlorothiazide (HCTZ) algorithm were assessed in patients with hypertension and type 2 diabetes mellitus (T2DM) who were uncontrolled by antihypertensive monotherapy. Eligible patients received AML/OM 5/20 mg for 4 weeks, followed by stepwise uptitration to AML/OM 5/40 mg, AML/OM 10/40 mg, AML/OM 10/40 mg+HCTZ 12.5 mg and AML/OM 10/40 mg+HCTZ 25 mg at 4-week intervals if blood pressure (BP) remained uncontrolled. The primary end point was the achievement of the seated cuff systolic BP (SeSBP) goal (<140 mm Hg, or <130 mm Hg for patients with T2DM) at week 12. Seated cuff BP was significantly reduced from baseline at all titration dose periods. At week 12, the cumulative SeSBP goal was achieved by 57.9% and 80.1% of patients in the T2DM and non-T2DM subgroups, respectively. Treatment was well tolerated, with low rates of peripheral edema. In summary, switching to a treatment algorithm based on AML/OM±HCTZ after failed monotherapy was safe and improved BP control in patients with hypertension and T2DM.

The design of an observational study of hypertension management, adherence and pressure control in Blood Pressure Success Zone Program participants.

AIMS: The Blood Pressure Success Zone (BPSZ) Program, a nationwide initiative, provides education in addition to a complimentary trial of one of three antihypertensive medications. The BPSZ Longitudinal Observational Study of Success (BPSZ-BLISS) aims to evaluate blood pressure (BP) control, adherence, persistence and patient satisfaction in a representative subset of BPSZ Program participants. The BPSZ-BLISS study design is described here. METHODS: A total of 20,000 physicians were invited to participate in the study. Using a call centre supported Interactive Voice Response System (IVRS), physicians report BP and other data at enrolment and every usual care visit up to 12 +/- 2 months; subjects self-report BPs, persistence, adherence and treatment satisfaction at 3, 6 and 12 months post-BPSZ Program enrolment. In addition to BPSZ Program enrolment medications, physicians prescribe antihypertensive medications and schedule visits as per usual care. The General Electric Healthcare database will be used as an external reference. RESULTS: After 18 months, over 700 IRB approved physicians consented and enrolled 10,067 eligible subjects (48% male; mean age 56 years; 27% newly diagnosed); 97% of physicians and 78% of subjects successfully entered IVRS enrolment data. Automated IVRS validations have maintained data quality (< 5% error on key variables). Enrolment was closed 30 April 2007; study completion is scheduled for June 2008. CONCLUSIONS: The evaluation of large-scale health education programmes requires innovative methodologies and data management and quality control processes. The BPSZ-BLISS design can provide insights into the conceptualisation and planning of similar studies.

Pregnancy outcomes in women with or without placental malaria infection.

OBJECTIVE: To assess delivery outcomes in women with placental malaria who presented at public hospitals in Kisumu, a holoendemic region in western Kenya. METHODS: A cross-sectional study using both histology and molecular biology was conducted with 90 consecutive pregnant women who presented at 3 hospitals during a 2-week period. Data collectors completed standardized questionnaires using each patient's hospital record and physical examination results, and registered birth indices such as weight, head circumference, and weight-head ratio. Malaria infection of the placenta was assessed using a molecular biology approach (for genomic differences among parasite species) as well as histology techniques. Of the 5 histologic classes of placental infection, class 1 corresponds to active infection and class 4 to past infection; class 2 and 3 to active chronic infection; and class 5 to uninfected individuals. Plasmodium species typing was determined by polymerase chain reaction amplification of the parasite's genome. RESULTS: In newborns at term, low birth weight was directly associated with classes 2 and 4 of placental infection (P = 0.053 and P = 0.003, respectively), and differences in birth weight remained significant between the 5 classes (P < 0.001) even after adjusting for parity and mother's age. Plasmodium falciparum was the only detected parasite. CONCLUSIONS: In Kisumu, infection with P. falciparum is an important cause of low birth weight and morbidity when it is associated with histologic classes 2 and 4 of placental infection. Moreover, polymerase chain reaction assays should be supported by ministries of health as an ancillary method of collecting data for malaria control during pregnancy and providing a baseline for future interventions.

Screening for microalbuminuria by use of microproteinuria.

We aimed to develop a reliable, low cost method to assess the early stages of renal impairment in diabetes, for use in high-risk populations in countries with limited resources. We evaluated a trichloroacetic acid (TCA) turbidimetric method for microproteinuria screening in patients with diabetes. The method was compared with an immunoturbidimetric procedure for the detection of microalbumuniuria. Both methods performed within limits of allowable uncertainty based on inter- and intra-individual variation. A urinary albumin/creatinine ratio of 3.0 g/mol, assumed as diagnostic of microalbuminuria, was found to correlate with a cut-off value of 24 mg/L for microproteinuria. The clinical sensitivity and specificity of the TCA method determined against this ratio were 86% and 90% respectively. The reliability and practicability of the TCA method renders it suitable for the detection of early stage renal damage, with emphasis on screening high-risk populations in countries with limited resources.

Screening for microalbuminuria by use of microproteinuria

We aimed to develop a reliable, low cost method to assess the early stages of renal impairment in diabetes, for use in high-risk populations in countries with limited resources. We evaluated a trichloroacetic acid [TCA] turbidimetric method for microproteinuria screening in patients with diabetes. The method was compared with an immunoturbidimetric procedure for the detection of microalbumuniuria. Both methods performed within limits of allowable uncertainty based on inter- and intra-individual variation. A urinary albumin/creatinine ratio of 3.0 g/mol, assumed as diagnostic of microalbuminuria, was found to correlate with a cut-off value of 24 mg/L for microproteinuria. The clinical sensitivity and specificity of the TCA method determined against this ratio were 86% and 90% respectively. The reliability and practicability of the TCA method renders it suitable for the detection of early stage renal damage, with emphasis on screening high-risk populations in countries with limited resources

Stool viruses among paediatric patients from a Nairobi clinic, Kenya.

OBJECTIVE: To document the clinical presentation and prevalence of stool viruses among children presenting with symptoms of acute gastroenteritis (AGE) at Gertrude's Garden Children's Hospital, Nairobi, Kenya. DESIGN: Retrospective case-control study. SETTING: A private paediatric clinic in Nairobi. RESULTS: Viral antigen was detectable in the stool samples of 21 (rotavirus alone in ten cases, adenovirus alone in seven cases, and both viruses in four cases). Diarrhoea was almost universally present (20/21 cases) and was reported more frequently than in a control group of ten children with clinical acute gastroenteritis whose stools tested negative for viruses. Fever, an elevated total leukocyte count, and neutrophilia were commonly observed in patients with viral gastroenteritis. Eight children with viral AGE were treated with antibiotics and eight children were admitted to hospital. CONCLUSION: A viral etiology can frequently be identified among children in Nairobi with AGE. Fever, an elevated leukocyte count, and neutrophilia were not helpful in differentiating viral from non-viral AGE in this series. Supportive management consisting of outpatient oral rehydration therapy without antibiotic treatment should be considered in the non-toxic child with AGE.

Are left ventricular mass, geometry and function related to vascular changes and/or insulin resistance in long-standing hypertension? ICARUS: a LIFE substudy.

Vascular hypertrophy and insulin resistance have been associated with abnormal left ventricular (LV) geometry in population studies. We wanted to investigate the influence of vascular hypertrophy and insulin resistance on LV hypertrophy and its function in patients with hypertension. In 89 patients with essential hypertension and electrocardiographic LV hypertrophy, we measured blood pressure; insulin sensitivity by hyperinsulinaemic euglucaemic clamp; minimal forearm vascular resistance (MFVR) by plethysmography; intima-media cross-sectional area of the common carotid arteries (IMA) by ultrasound; and LV mass, relative wall thickness (RWT), systolic function and diastolic filling by echocardiography after two weeks of placebo treatment. LV mass index correlated to IMA/height (r=0.36, P=0.001), serum insulin (r=-0.25, P<0.05), plasma glucose (r=-0.34, P<0.01), and showed a tendency towards a correlation to insulin sensitivity (r=0.21, P=0.051), but was unrelated to MFVR. Deceleration time of early diastolic transmitral flow positively correlated to IMA/height (r=0.30, P<0.01). The ratio between early and atrial LV filling peak flow velocity negatively correlated to MFVR(men) (r=-0.30, P<0.05). Endocardial and midwall systolic LV function were not related to vascular hypertrophy, plasma glucose, serum insulin or insulin sensitivity. In conclusion, insulin resistance was not related to LV hypertrophy or reduced LV function. However, high thickness of the common carotid arteries was associated with LV hypertrophy and high deceleration time of early diastolic transmitral flow. High MFVR was associated with low ratio between early and atrial LV filling peak flow velocity. This may suggest that systemic vascular hypertrophy contributes to abnormal diastolic LV relaxation in patients with hypertension and electrocardiographic LV hypertrophy.

Heritability of left atrial size in the Tecumseh population.

BACKGROUND: Little is known about the determinants of atrial size, and no study has analyzed whether genetic factors are involved in the pathogenesis of LA enlargement. MATERIALS AND METHODS: We studied the heritability of echocardiographic left atrial size in 290 parents from the Tecumseh Blood Pressure Study and 251 children from the Tecumseh Offspring Study. All data from the parents and children were obtained at the same field office in Tecumseh, USA. Left atrial dimension was determined echocardiographically in accordance with American Society of Echocardiography guidelines with the use of leading-edge-to-leading-edge measurements of the maximal distance between the posterior aortic root wall and the posterior left atrial wall at end systole. RESULTS: For correlation between the left atrial dimensions of the parents and their offspring, several models were generated to adjust the atrial dimensions in both groups for an increasing number of clinical variables. After removing the effect of age, gender, height, weight, skinfold thickness, and systolic blood pressure, parent-child correlation for left atrial size was 0.19 (P = 0.007). Further adjustment for left ventricular mass and for measuring left ventricular diastolic function increased the correlation to 0.25 (P = 0.001). CONCLUSIONS: The present data indicate that heredity can explain a small but definite proportion of the variance in left atrial dimension.

Identification of a novel phosphonocarboxylate inhibitor of Rab geranylgeranyl transferase that specifically prevents Rab prenylation in osteoclasts and macrophages.

Nitrogen-containing bisphosphonate drugs inhibit bone resorption by inhibiting FPP synthase and thereby preventing the synthesis of isoprenoid lipids required for protein prenylation in bone-resorbing osteoclasts. NE10790 is a phosphonocarboxylate analogue of the potent bisphosphonate risedronate and is a weak anti-resorptive agent. Although NE10790 was a poor inhibitor of FPP synthase, it did inhibit prenylation in J774 macrophages and osteoclasts, but only of proteins of molecular mass approximately 22-26 kDa, the prenylation of which was not affected by peptidomimetic inhibitors of either farnesyl transferase (FTI-277) or geranylgeranyl transferase I (GGTI-298). These 22-26-kDa proteins were shown to be geranylgeranylated by labelling J774 cells with [(3)H]geranylgeraniol. Furthermore, NE10790 inhibited incorporation of [(14)C]mevalonic acid into Rab6, but not into H-Ras or Rap1, proteins that are modified by FTase and GGTase I, respectively. These data demonstrate that NE10790 selectively prevents Rab prenylation in intact cells. In accord, NE10790 inhibited the activity of recombinant Rab GGTase in vitro, but did not affect the activity of recombinant FTase or GGTase I. NE10790 therefore appears to be the first specific inhibitor of Rab GGTase to be identified. In contrast to risedronate, NE10790 inhibited bone resorption in vitro without markedly affecting osteoclast number or the F-actin "ring" structure in polarized osteoclasts. However, NE10790 did alter osteoclast morphology, causing the formation of large intracellular vacuoles and protrusion of the basolateral membrane into large, "domed" structures that lacked microvilli. The anti-resorptive activity of NE10790 is thus likely due to disruption of Rab-dependent intracellular membrane trafficking in osteoclasts.

Genetic contribution to the variance in left ventricular mass: the Tecumseh Offspring Study.

OBJECTIVE: To estimate the contribution of heredity to the variance in left ventricular mass (LVM), and to ascertain whether genetic factors may interact with non-genetic factors in promoting LVM growth. SUBJECTS AND SETTING: The study population consisted of 290 healthy parents and 251 healthy children living in Tecumseh, Michigan, USA. MAIN OUTCOME MEASURE: Correlation of parents' LVM with offspring's LVM adjusting for a number of clinical variables. METHODS: LVM in parents and offspring was measured with M-mode echocardiography by the same investigators. RESULTS: Parents unadjusted LVM was unrelated to offspring unadjusted LVM, but after removing the confounding effect of age, sex, anthropometric measurements, systolic blood pressure, plasma insulin and urinary sodium excretion, parent-child correlation for LVM was 0.28 (P = 0.006). The relative contribution of parental-adjusted LVM and of several offspring phenotypic and environmental variables on offspring LVM was evaluated by multivariable regression analysis. When age, gender, anthropometric measurements and systolic blood pressure were accounted for, adjusted LVM of parents explained only 1.6% of the total variance in offspring LVM. However, after inclusion of insulin and urinary sodium in the model heredity explained 7.6% of the total variance in offspring LVM, and its predictive power was second only to that of child's height. Furthermore, an interactive effect of parental LVM with offspring systolic blood pressure was found on child's left ventricular mass. CONCLUSION: Heredity can explain a small, but definite proportion of the variance in LVM. Higher blood pressure favors the phenotypic expression of the genes that regulate LVM growth.

Cells in regenerating deer antler cartilage provide a microenvironment that supports osteoclast differentiation.

Deer antlers are a rare example of mammalian epimorphic regeneration. Each year, the antlers re-grow by a modified endochondral ossification process that involves extensive remodelling of cartilage by osteoclasts. This study identified regenerating antler cartilage as a site of osteoclastogenesis in vivo. An in vitro model was then developed to study antler osteoclast differentiation. Cultured as a high-density micromass, cells from non-mineralised cartilage supported the differentiation of large numbers of osteoclast-like multinucleated cells (MNCs) in the absence of factors normally required for osteoclastogenesis. After 48 h of culture, tartrate-resistant acid phosphatase (TRAP)-positive mononuclear cells (osteoclast precursors) were visible, and by day 14 a large number of TRAP-positive MNCs had formed (783+/-200 per well, mean +/- s.e.m., N=4). Reverse transcriptase/polymerase chain reaction (RT-PCR) showed that receptor activator of NF &kgr; B ligand (RANKL) and macrophage colony stimulating factor (M-CSF) mRNAs were expressed in micromass cultures. Antler MNCs have the phenotype of osteoclasts from mammalian bone; they expressed TRAP, vitronectin and calcitonin receptors and, when cultured on dentine, formed F-actin rings and large resorption pits. When cultured on glass, antler MNCs appeared to digest the matrix of the micromass and endocytose type I collagen. Matrix metalloproteinase-9 (MMP-9) may play a role in the resorption of this non-mineralised matrix since it is highly expressed in 100 % of MNCs. In contrast, cathepsin K, another enzyme expressed in osteoclasts from bone, is only highly expressed in resorbing MNCs cultured on dentine. This study identifies the deer antler as a valuable model that can be used to study the differentiation and function of osteoclasts in adult regenerating mineralised tissues.

Prehypertension: a possible target for antihypertensive medication.

Vascular changes associated with elevated blood pressure may precede the clinical diagnosis of hypertension. Even after the diagnosis is made, associated coronary heart disease and renal disease continue to progress, despite adequate blood pressure control. Early treatment of blood pressure may reduce the incidence of clinical hypertension and reduce the long-term consequences of hypertension. Animal studies have shown that early blood pressure lowering, through blockade of the renin-angiotensin system, prevents long-term hypertension. Prevention is an important goal in the treatment of hypertension. Our best attempts to prevent hypertension use nonpharmacologic methods of diet and exercise. These methods are fraught with difficulties of implementation and compliance that limit their success. Finding novel approaches to prevent hypertension may have a major impact on the incidence of hypertension. We are investigating the effect of 2 years of treatment with an angiotensin receptor blocker (candesartan cilexitil) compared with placebo, followed by 2 years of follow-up, on the incidence of hypertension in patients with high-normal blood pressure. Incidence of hypertension after discontinuation of active treatment will be compared with the incidence in the placebo group. There will be 1000 patients enrolled in the study, which will be completed in 2004.

Determinants of left ventricular structure and mass in young subjects with sympathetic over-activity. The Tecumseh Offspring Study.

OBJECTIVE: In this study, we tested the hypothesis that sympathetic over-activity may cause metabolic abnormalities and affect left ventricular (LV) structure and mass early in life. SUBJECTS AND SETTING: The study population consisted of 111 healthy adolescents and young adults living in Tecumseh, Michigan (USA). MAIN OUTCOME MEASURES: Correlations of LV mass and structure with several clinical variables in relation to the activity of the sympathetic nervous system. METHODS: Power spectrum density estimates of heart rate variability were calculated with an auto-regressive method, and subjects were divided by cluster analysis into two groups according to low-frequency and high-frequency components. LV data were obtained by echocardiographic assessment RESULTS: Subjects with signs of sympathetic over-activity (n = 38, group 1) had higher heart rate, blood pressure (BP), waist/hip ratio and cholesterol levels than the rest of the group (n = 73, group 2). In group 1 subjects, insulin emerged as the strongest univariate correlate of interventricular septum and posterior wall thicknesses (P< 0.001 for both) and of LV mass (P= 0.009). These relationships remained significant when body mass index was accounted for. By contrast, the marginal univariate relationship with diastolic BP did not remain significant in multivariate analysis. In group 2 subjects, BP was strongly correlated with LV wall thickness and mass both in univariate (P values from 0.03 to < 0.001) and multivariate analyses, while insulin was not. The interactive effect of sympathetic activity and insulin on echocardiographic data was confirmed by multivariate analyses performed in the subjects grouped together (P values from 0.02 to 0.001 for the sympathetic activity x insulin interaction term). CONCLUSIONS: In young subjects with heightened sympathetic activity and initial metabolic abnormalities, insulin is a strong determinant of LV wall thickness and geometry, while in subjects with normal autonomic nervous system activity, the main determinant of left ventricular size is the haemodynamic load.

Blood viscosity, plasma adrenaline and fasting insulin in hypertensive patients with left ventricular hypertrophy. ICARUS, a LIFE Substudy. Insulin CARotids US Scandinavica.

We have seen relationships between whole blood viscosity (WBV) and components of the metabolic cardiovascular syndrome in borderline hypertensive young men and suggested that sympathetic nervous system (SNS) activity may be a mediator. In the present study we aimed to test this hypothesis in established hypertension and to investigate the relationship between WBV and cardiac dimensions. Unmedicated patients (n = 42) with stage II-III hypertension and electrocardiographic left ventricular hypertrophy (LVH) underwent hyperinsulinemic isoglycemic glucose clamp to assess glucose disposal rate (GDR) and echocardiographic studies. WBV, plasma catecholamines and insulin were measured in arterialized venous blood. WBV at high shear rate correlated with baseline plasma adrenaline (r = 0.33, p = 0.04) and fasting insulin (r = 0.34, p = 0.04) while there was a negative trend for GDR (r = -0.21, p = 0.2). WBV at low shear rate correlated with plasma adrenaline (r = 0.49, p = 0.002) and resting heart rate (r = 0.36, p = 0.02). WBV was higher in smokers than in non-smokers (p = 0.02) and in males than in females (p = 0.02). Fasting insulin independently explained 12% of the variation in WBV at high shear, while baseline adrenaline independently explained 17% of the variation in WBV at low shear. Systolic blood pressure explained 31% of the variation in LV mass index. Thus, we demonstrate positive relationships between blood viscosity versus plasma adrenaline and fasting insulin in hypertensive patients with LVH. We suggest that adrenergic activity may increase hematocrit and viscosity and hence reduce insulin sensitivity.

Relative influence of insulin resistance versus blood pressure on vascular changes in longstanding hypertension. ICARUS, a LIFE sub study. Insulin Carotids US Scandinavia.

BACKGROUND: Insulin resistance is associated with hypertension. The relative influences of hyperinsulinaemia and high blood pressure on vascular hypertrophy and carotid distensibility is unclear in patients with longstanding hypertension. METHODS: In 88 unmedicated patients with stage II-III hypertension and left ventricular hypertrophy on electrocardiogram we measured blood pressure, minimal forearm vascular resistance (MFVR) using plethysmography, intima-media thickness (IMT) and the wall distensibility of the common carotid arteries using ultrasound, and insulin sensitivity using a 2-h isoglycaemic hyperinsulinaemic clamp. RESULTS: IMT was positively correlated to systolic blood pressure (r= 0.26, P < 0.05), whole body glucose uptake index (M/IG; r= 0.22, P< 0.05), age (r= 0.24, P< 0.05) and negatively correlated to body mass index (r= -0.24, P < 0.05); IMT did not correlate to fasting serum insulin (r= -0.14, NS). In men (n = 64) MFVR was positively correlated to systolic blood pressure (r = 0.30, P < 0.05), but was unrelated to M/G and serum insulin. The distensibility of the common carotid arteries was negatively correlated to systolic blood pressure (r = -0.40, P< 0.001) and in untreated patients (n = 22) positively correlated to M/IG (r = 0.47, P < 0.05). CONCLUSIONS: High systolic blood pressure was related to vascular hypertrophy, whereas hyperinsulinaemia and insulin resistance were not, suggesting that longstanding high blood pressure is a far more important determinant for structural vascular changes than insulin resistance at this stage of the hypertensive disease. However, hyperinsulinaemia and insulin resistance were associated with low distensibility of the common carotid arteries in the subgroup of never treated hypertensive patients.

The kinetic mechanism of the hairpin ribozyme in vivo: influence of RNA helix stability on intracellular cleavage kinetics.

The relationship between hairpin ribozyme structure, and cleavage and ligation kinetics, and equilibria has been characterized extensively under a variety of reaction conditions in vitro. We developed a quantitative assay of hairpin ribozyme cleavage activity in yeast to learn how structure-function relationships defined for RNA enzymes in vitro relate to RNA-mediated reactions in cells. Here, we report the effects of variation in the stability of an essential secondary structure element, H1, on intracellular cleavage kinetics. H1 is the base-paired helix formed between ribozyme and 3' cleavage product RNAs. H1 sequences with fewer than three base-pairs fail to support full activity in vitro or in vivo, arguing against any significant difference in the stability of short RNA helices under in vitro and intracellular conditions. Under standard conditions in vitro that include 10 mM MgCl(2), the internal equilibrium between cleavage and ligation of ribozyme-bound products favors ligation. Consequently, ribozymes with stable H1 sequences display sharply reduced self-cleavage rates, because cleavage is reversed by rapid re-ligation of bound products. In contrast, ribozymes with as many as 26 base-pairs in H1 continue to self-cleave at maximum rates in vivo. The failure of large products to inhibit cleavage could be explained if intracellular conditions promote rapid product dissociation or shift the internal equilibrium to favor cleavage. Model experiments in vitro suggest that the internal equilibrium between cleavage and ligation of bound products is likely to favor cleavage under intracellular ionic conditions.