Diabetes and cardiovascular disease. The Framingham study

Based on 20 years of surveillance of the Framingham cohort relating subsequent cardiovascular events to prior evidence of diabetes, a twofold to threefold increased risk of clinical atherosclerotic disease was reported. The relative impact was greatest for intermittent claudication (IC) and congestive heart failure (CHF) and least for coronary heart disease (CHD), which was, nevertheless, on an absolute scale the chief sequela. The relative impact was substantially greater for women than for men. For each of the cardiovascular diseases (CVD), morbidity and mortality were higher for diabetic women than for nondiabetic men. After adjustment for other associated risk factors, the relative impact of diabetes on CHD, IC, or stroke incidence was the same for women as for men; for CVD death and CHF, it was greater for women. Cardiovascular mortality was actually about as great for diabetic women as for diabetic men.

Diabetes and cardiovascular disease. The Framingham study

Based on 20 years of surveillance of the Framingham cohort relating subsequent cardiovascular events to prior evidence of diabetes, a twofold to threefold increased risk of clinical atherosclerotic disease was reported. The relative impact was greatest for intermittent claudication (IC) and congestive heart failure (CHF) and least for coronary heart disease (CHD), which was, nevertheless, on an absolute scale the chief sequela. The relative impact was substantially greater for women than for men. For each of the cardiovascular diseases (CVD), morbidity and mortality were higher for diabetic women than for nondiabetic men. After adjustment for other associated risk factors, the relative impact of diabetes on CHD, IC, or stroke incidence was the same for women as for men; for CVD death and CHF, it was greater for women. Cardiovascular mortality was actually about as great for diabetic women as for diabetic men.

Reflex regulation of arterial pressure during sleep in man. A quantitative method of assessing baroreflex sensitivity

The control of arterial pressure during sleep was studied in 13 untreated, unsedated subjects aged 20 to 46, including 7 with hypertension. Arterial pressure was measured directly. A transient rise of arterial pressure up to 30 mm Hg was produced by the sudden intravenous injection of 0.25 to 2 µg of angiotensin. Linear plots were obtained in 10 of 13 subjects when the systolic pressures of successive pulses during the pressure rise were plotted against the pulse intervals which began the next beat. The relationship was disturbed by movement or arousal, and was better when pulse intervals falling in inspiration were discarded.

The slope of the line (milliseconds of cardiac slowing per millimeter rise in systolic pressure) in the awake subject ranged from 2 to 15.5 msec/mm Hg, and from 4.5 to 28.9 during sleep. Reflex sensitivity was highest in dreaming sleep. In 7 of 10 subjects, baroreflex sensitivity increased significantly during sleep; in 6, the prevailing arterial pressure was inversely correlated with the baroreflex sensitivity. The pressure appeared to be the dependent variable. It is concluded that the baroreceptor reflex are can be rapidly reset, particularly during sleep. The lower arterial pressures during sleep may be actively maintained in some subjects by increased baroreflex sensitivity.

Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids: results of the OmniHeart randomized trial

CONTEXT

Reduced intake of saturated fat is widely recommended for prevention of cardiovascular disease. The type of macronutrient that should replace saturated fat remains uncertain.

OBJECTIVE

To compare the effects of 3 healthful diets, each with reduced saturated fat intake, on blood pressure and serum lipids.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, 3-period, crossover feeding study (April 2003 to June 2005) conducted in Baltimore, Md, and Boston, Mass. Participants were 164 adults with prehypertension or stage 1 hypertension. Each feeding period lasted 6 weeks and body weight was kept constant.

INTERVENTIONS

A diet rich in carbohydrates; a diet rich in protein, about half from plant sources; and a diet rich in unsaturated fat, predominantly monounsaturated fat.

MAIN OUTCOME MEASURES

Systolic blood pressure and low-density lipoprotein cholesterol.

RESULTS

Blood pressure, low-density lipoprotein cholesterol, and estimated coronary heart disease risk were lower on each diet compared with baseline. Compared with the carbohydrate diet, the protein diet further decreased mean systolic blood pressure by 1.4 mm Hg (P = .002) and by 3.5 mm Hg (P = .006) among those with hypertension and decreased low-density lipoprotein cholesterol by 3.3 mg/dL (0.09 mmol/L; P = .01), high-density lipoprotein cholesterol by 1.3 mg/dL (0.03 mmol/L; P = .02), and triglycerides by 15.7 mg/dL (0.18 mmol/L; P<.001). Compared with the carbohydrate diet, the unsaturated fat diet decreased systolic blood pressure by 1.3 mm Hg (P = .005) and by 2.9 mm Hg among those with hypertension (P = .02), had no significant effect on low-density lipoprotein cholesterol, increased high-density lipoprotein cholesterol by 1.1 mg/dL (0.03 mmol/L; P = .03), and lowered triglycerides by 9.6 mg/dL (0.11 mmol/L; P = .02). Compared with the carbohydrate diet, estimated 10-year coronary heart disease risk was lower and similar on the protein and unsaturated fat diets.

CONCLUSION

In the setting of a healthful diet, partial substitution of carbohydrate with either protein or monounsaturated fat can further lower blood pressure, improve lipid levels, and reduce estimated cardiovascular risk. Clinical Trials Registration ClinicalTrials.gov Identifier: NCT00051350.

Relationship of functional health literacy to patients' knowledge of their chronic disease. A study of patients with hypertension and diabetes

BACKGROUND

Inadequate functional health literacy is common, but its impact on patients with chronic diseases is not well described.

OBJECTIVE

To examine among patients with hypertension or diabetes the relationship between their functional health literacy level and their knowledge of their chronic disease and treatment.

METHODS

We conducted a cross-sectional survey of patients with hypertension and diabetes presenting to the general medicine clinics at 2 urban public hospitals. Literacy was measured by the Test of Functional Health Literacy in Adults. Knowledge of their illness was assessed in patients with diabetes or hypertension using 21 hypertension and 10 diabetes questions based on key elements in educational materials used in our clinics.

RESULTS

A total of 402 patients with hypertension and 114 patients with diabetes were enrolled. Mean (+/- SD) knowledge scores for patients with hypertension with inadequate (n = 189), marginal (n = 49), or adequate (n = 155) literacy were 13.2 +/- 3.1, 15.3 +/- 2.2, and 16.5 +/- 2.3, respectively (range, 4-20; P < .001). A total of 92% of patients with hypertension and adequate literacy levels knew that a blood pressure reading of 160/100 mm Hg was high compared with 55% of those in the lowest reading level (P < .001). Mean (+/- SD) knowledge scores for patients with diabetes with inadequate (n = 50), marginal (n = 13), or adequate (n = 51) literacy were 5.8 +/- 2.1, 6.8 +/- 1.9, and 8.1 +/- 1.6, respectively (range, 1-10; P < .001). A total of 94% of patients with diabetes and adequate functional health literacy knew the symptoms of hypoglycemia compared with 50% of those with inadequate literacy (P < .001).

CONCLUSIONS

Inadequate functional health literacy poses a major barrier to educating patients with chronic diseases, and current efforts to overcome this appear unsuccessful.

Stroke subtype, vascular risk factors, and total MRI brain small-vessel disease burden

OBJECTIVES

In this cross-sectional study, we tested the construct validity of a "total SVD score," which combines individual MRI features of small-vessel disease (SVD) in one measure, by testing associations with vascular risk factors and stroke subtype.

METHODS

We analyzed data from patients with lacunar or nondisabling cortical stroke from 2 prospective stroke studies. Brain MRI was rated for the presence of lacunes, white matter hyperintensities, cerebral microbleeds, and perivascular spaces independently. The presence of each SVD feature was summed in an ordinal "SVD score" (range 0-4). We tested associations with vascular risk factors, stroke subtype, and cerebral atrophy using ordinal regression analysis.

RESULTS

In 461 patients, multivariable analysis found that age (odds ratio [OR] 1.10, 95% confidence interval [CI] 1.08-1.12), male sex (OR 1.58, 95% CI 1.10-2.29), hypertension (OR 1.50, 95% CI 1.02-2.20), smoking (OR 2.81, 95% CI 1.59-3.63), and lacunar stroke subtype (OR 2.45, 95% CI 1.70-3.54) were significantly and independently associated with the total SVD score. The score was not associated with cerebral atrophy.

CONCLUSIONS

The total SVD score may provide a more complete estimate of the full impact of SVD on the brain, in a simple and pragmatic way. It could have potential for patient or risk stratification or early efficacy assessment in clinical trials of interventions to prevent SVD progression and may (after further testing) have a useful role in clinical practice.

The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes

BACKGROUND

The health benefits of greenspaces have demanded the attention of policymakers since the 1800s. Although much evidence suggests greenspace exposure is beneficial for health, there exists no systematic review and meta-analysis to synthesise and quantify the impact of greenspace on a wide range of health outcomes.

OBJECTIVE

To quantify evidence of the impact of greenspace on a wide range of health outcomes.

METHODS

We searched five online databases and reference lists up to January 2017. Studies satisfying a priori eligibility criteria were evaluated independently by two authors.

RESULTS

We included 103 observational and 40 interventional studies investigating ~100 health outcomes. Meta-analysis results showed increased greenspace exposure was associated with decreased salivary cortisol -0.05 (95% CI -0.07, -0.04), heart rate -2.57 (95% CI -4.30, -0.83), diastolic blood pressure -1.97 (95% CI -3.45, -0.19), HDL cholesterol -0.03 (95% CI -0.05, <-0.01), low frequency heart rate variability (HRV) -0.06 (95% CI -0.08, -0.03) and increased high frequency HRV 91.87 (95% CI 50.92, 132.82), as well as decreased risk of preterm birth 0.87 (95% CI 0.80, 0.94), type II diabetes 0.72 (95% CI 0.61, 0.85), all-cause mortality 0.69 (95% CI 0.55, 0.87), small size for gestational age 0.81 (95% CI 0.76, 0.86), cardiovascular mortality 0.84 (95% CI 0.76, 0.93), and an increased incidence of good self-reported health 1.12 (95% CI 1.05, 1.19). Incidence of stroke, hypertension, dyslipidaemia, asthma, and coronary heart disease were reduced. For several non-pooled health outcomes, between 66.7% and 100% of studies showed health-denoting associations with increased greenspace exposure including neurological and cancer-related outcomes, and respiratory mortality.

CONCLUSIONS

Greenspace exposure is associated with numerous health benefits in intervention and observational studies. These results are indicative of a beneficial influence of greenspace on a wide range of health outcomes. However several meta-analyses results are limited by poor study quality and high levels of heterogeneity. Green prescriptions involving greenspace use may have substantial benefits. Our findings should encourage practitioners and policymakers to give due regard to how they can create, maintain, and improve existing accessible greenspaces in deprived areas. Furthermore the development of strategies and interventions for the utilisation of such greenspaces by those who stand to benefit the most.

Cardiac hypertrophy is inhibited by antagonism of ADAM12 processing of HB-EGF: metalloproteinase inhibitors as a new therapy

G-protein-coupled receptor (GPCR) agonists are well-known inducers of cardiac hypertrophy. We found that the shedding of heparin-binding epidermal growth factor (HB-EGF) resulting from metalloproteinase activation and subsequent transactivation of the epidermal growth factor receptor occurred when cardiomyocytes were stimulated by GPCR agonists, leading to cardiac hypertrophy. A new inhibitor of HB-EGF shedding, KB-R7785, blocked this signaling. We cloned a disintegrin and metalloprotease 12 (ADAM12) as a specific enzyme to shed HB-EGF in the heart and found that dominant-negative expression of ADAM12 abrogated this signaling. KB-R7785 bound directly to ADAM12, suggesting that inhibition of ADAM12 blocked the shedding of HB-EGF. In mice with cardiac hypertrophy, KB-R7785 inhibited the shedding of HB-EGF and attenuated hypertrophic changes. These data suggest that shedding of HB-EGF by ADAM12 plays an important role in cardiac hypertrophy, and that inhibition of HB-EGF shedding could be a potent therapeutic strategy for cardiac hypertrophy.

Weight, weight change, and coronary heart disease in women. Risk within the 'normal' weight range

OBJECTIVE--To assess the validity of the 1990 US weight guidelines for women that support a substantial gain in weight at approximately 35 years of age and recommend a range of body mass index (BMI) (defined as weight in kilograms divided by the square of height in meters) from 21 to 27 kg/m2, in terms of coronary heart disease (CHD) risk in women. DESIGN--Prospective cohort study. SETTING--Female registered nurses in the United States. PARTICIPANTS--A total of 115,818 women aged 30 to 55 years in 1976 and without a history of previous CHD. MAIN OUTCOME MEASURE--Incidence of CHD defined as nonfatal myocardial infarction or fatal CHD. RESULTS--During 14 years of follow-up, 1292 cases of CHD were ascertained. After controlling for age, smoking, menopausal status, postmenopausal hormone use, and parental history of CHD and using as a reference women with a BMI of less than 21 kg/m2, relative risks (RRs) and 95% confidence intervals (CIs) for CHD were 1.19 (0.97 to 1.44) for a BMI of 21 to 22.9 kg/m2, 1.46 (1.20 to 1.77) for a BMI of 23 to 24.9 kg/m2, 2.06 (1.72 to 2.48) for a BMI of 25 to 28.9 kg/m2, and 3.56 (2.96 to 4.29) for a BMI of 29 kg/m2 or more. Women who gained weight from 18 years of age were compared with those with stable weight (+/- 5 kg) in analyses that controlled for the same variables as well as BMI at 18 years of age. The RRs and CIs were 1.25 (1.01 to 1.55) for a 5- to 7.9-kg gain, 1.64 (1.33 to 2.04) for an 8- to 10.9-kg gain, 1.92 (1.61 to 2.29) for an 11- to 19-kg gain, and 2.65 (2.17 to 3.22) for a gain of 20 kg or more. Among women with the BMI range of 18 to 25 kg/m2, weight gain after 18 years of age remained a strong predictor of CHD risk. CONCLUSIONS--Higher levels of body weight within the "normal" range, as well as modest weight gains after 18 years of age, appear to increase risks of CHD in middle-aged women. These data provide evidence that current US weight guidelines may be falsely reassuring to the large proportion of women older than 35 years who are within the current guidelines but have potentially avoidable risks of CHD.

Association of Type 1 Diabetes vs Type 2 Diabetes Diagnosed During Childhood and Adolescence With Complications During Teenage Years and Young Adulthood

Importance

The burden and determinants of complications and comorbidities in contemporary youth-onset diabetes are unknown.

Objective

To determine the prevalence of and risk factors for complications related to type 1 diabetes vs type 2 diabetes among teenagers and young adults who had been diagnosed with diabetes during childhood and adolescence.

Design, Setting, and Participants

Observational study from 2002 to 2015 in 5 US locations, including 2018 participants with type 1 and type 2 diabetes diagnosed at younger than 20 years, with single outcome measures between 2011 and 2015.

Exposures

Type 1 and type 2 diabetes and established risk factors (hemoglobin A1c level, body mass index, waist-height ratio, and mean arterial blood pressure).

Main Outcomes and Measures

Diabetic kidney disease, retinopathy, peripheral neuropathy, cardiovascular autonomic neuropathy, arterial stiffness, and hypertension.

Results

Of 2018 participants, 1746 had type 1 diabetes (mean age, 17.9 years [SD, 4.1]; 1327 non-Hispanic white [76.0%]; 867 female patients [49.7%]), and 272 had type 2 (mean age, 22.1 years [SD, 3.5]; 72 non-Hispanic white [26.5%]; 181 female patients [66.5%]). Mean diabetes duration was 7.9 years (both groups). Patients with type 2 diabetes vs those with type 1 had higher age-adjusted prevalence of diabetic kidney disease (19.9% vs 5.8%; absolute difference [AD], 14.0%; 95% CI, 9.1%-19.9%; P < .001), retinopathy (9.1% vs 5.6%; AD, 3.5%; 95% CI, 0.4%-7.7%; P = .02), peripheral neuropathy (17.7% vs 8.5%; AD, 9.2%; 95% CI, 4.8%-14.4%; P < .001), arterial stiffness (47.4% vs 11.6%; AD, 35.9%; 95% CI, 29%-42.9%; P < .001), and hypertension (21.6% vs 10.1%; AD, 11.5%; 95% CI, 6.8%-16.9%; P < .001), but not cardiovascular autonomic neuropathy (15.7% vs 14.4%; AD, 1.2%; 95% CI, -3.1% to 6.5; P = .62). After adjustment for established risk factors measured over time, participants with type 2 diabetes vs those with type 1 had significantly higher odds of diabetic kidney disease (odds ratio [OR], 2.58; 95% CI, 1.39-4.81; P=.003), retinopathy (OR, 2.24; 95% CI, 1.11-4.50; P = .02), and peripheral neuropathy (OR, 2.52; 95% CI, 1.43-4.43; P = .001), but no significant difference in the odds of arterial stiffness (OR, 1.07; 95% CI, 0.63-1.84; P = .80) and hypertension (OR, 0.85; 95% CI, 0.50-1.45; P = .55).

Conclusions and Relevance

Among teenagers and young adults who had been diagnosed with diabetes during childhood or adolescence, the prevalence of complications and comorbidities was higher among those with type 2 diabetes compared with type 1, but frequent in both groups. These findings support early monitoring of youth with diabetes for development of complications.

Persistence of use of lipid-lowering medications: a cross-national study

CONTEXT

Although clinical trials have demonstrated the benefits of lipid-lowering therapy, little is known about how these drugs are prescribed or used in the general population.

OBJECTIVE

To estimate predictors of persistence with therapy for lipid-lowering drug regimens in typical populations of patients in the United States and Canada.

DESIGN

A cohort study defining all prescriptions filled for lipid-lowering drugs during 1 year, as well as patients' demographic and clinical characteristics.

SETTING

New Jersey's Medicaid and Pharmacy Assistance for the Aged and Disabled programs and Quebec's provincial medical care program.

PATIENTS

All continuously enrolled patients older than 65 years who filled 1 or more prescriptions for lipid-lowering drugs (N = 5611 in the US programs, and N = 1676 drawn from a 10% sample in Quebec).

MAIN OUTCOME MEASURES

Proportion of days during the study year for which patients had filled prescriptions for lipid-lowering drugs; predictors of good vs poor persistence with therapy.

RESULTS

In both populations, patients failed to fill prescriptions for lipid-lowering drugs for about 40% of the study year. Persistence rates with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors were significantly higher than those seen with cholestyramine (64.3% vs 36.6% of days with drug available, respectively). Patients with hypertension, diabetes, or coronary artery disease had significantly higher rates of persistence with lipid-lowering regimens. In New Jersey, multivariable analysis indicated that the poorest patients (those enrolled in Medicaid) had lower rates of drug use than less indigent patients (those enrolled in Pharmacy Assistance for the Aged and Disabled) after adjusting for possible confounders, despite virtually complete drug coverage in both programs. When rates of use were measured in the US population for the 5 years following the study year, only 52% of surviving patients who were initially prescribed lipid-lowering drugs were still filling prescriptions for this drug class.

CONCLUSION

In all populations studied, patients who were prescribed lipid-lowering drug regimens remained without filled prescriptions for over a third of the study year on average. Rates of persistence varied substantially with choice of agent prescribed, comorbidity, and socioeconomic status, despite universal coverage of prescription drug costs. After 5 years, about half of the surviving original cohort in the United States had stopped using lipid-lowering therapy altogether.

The neonatal blood count in health and disease. I. Reference values for neutrophilic cells

Reference ranges for absolute total neutrophils/mm3, absolute immature neutrophils/mm3, and the fraction of immature to total neutrophils (I:T proportion) during the first 28 days of life are developed from 585 peripheral blood counts obtained from 304 normal neonates and 320 counts obtained from 130 neonates with perinatal complications demonstrated to have no statistically significant effect on neutrophil dynamics. Perinatal factors other than bacterial disease which significantly alter neutrophil dynamics include maternal hypertension, maternal fever prior to delivery, hemolytic disease, and periventricular hemorrhage. The predictive value of these reference ranges in identifying bacterial disease in the first week of age varies with the neutrophil factor evaluated and the clinical setting. Neutropenia in the presence of respiratory distress in the first 72 hours had an 84% likelihood of signifying bacterial disease, whereas neutropenia in the presence of asphyxia had a 68% likelihood of signifying bacterial disease. An abnormal I:T proportion had an accuracy of 82% and 61%, respectively, in the same clinical settings. Elevations of either immature or total neutrophils were less specific. Interpretation of abnormal neutrophil factors must include consideration of both infectious and noninfectious perinatal events.

Endocrine regulation of human fetal growth: the role of the mother, placenta, and fetus

The environment in which the fetus develops is critical for its survival and long-term health. The regulation of normal human fetal growth involves many multidirectional interactions between the mother, placenta, and fetus. The mother supplies nutrients and oxygen to the fetus via the placenta. The fetus influences the provision of maternal nutrients via the placental production of hormones that regulate maternal metabolism. The placenta is the site of exchange between mother and fetus and regulates fetal growth via the production and metabolism of growth-regulating hormones such as IGFs and glucocorticoids. Adequate trophoblast invasion in early pregnancy and increased uteroplacental blood flow ensure sufficient growth of the uterus, placenta, and fetus. The placenta may respond to fetal endocrine signals to increase transport of maternal nutrients by growth of the placenta, by activation of transport systems, and by production of placental hormones to influence maternal physiology and even behavior. There are consequences of poor fetal growth both in the short term and long term, in the form of increased mortality and morbidity. Endocrine regulation of fetal growth involves interactions between the mother, placenta, and fetus, and these effects may program long-term physiology.

Cardiovascular disease risk in healthy children and its association with body mass index: systematic review and meta-analysis

OBJECTIVES

To describe the association and its magnitude between body mass index category, sex, and cardiovascular disease risk parameters in school aged children in highly developed countries.

DESIGN

Systematic review and meta-analysis. Quality of included studies assessed by an adapted version of the Cochrane Collaboration's risk of bias assessment tool. Results of included studies in meta-analysis were pooled and analysed by Review Manager version 5.1.

DATA SOURCES

Embase, PubMed, EBSCOHost's cumulative index to nursing and allied health literature, and the Web of Science databases for papers published between January 2000 and December 2011.

REVIEW METHODS

Healthy children aged 5 to 15 in highly developed countries enrolled in studies done after 1990 and using prospective or retrospective cohort, cross sectional, case-control, or randomised clinical trial designs in school, outpatient, or community settings. Included studies had to report an objective measure of weight and at least one prespecified risk parameter for cardiovascular disease.

RESULTS

We included 63 studies of 49 220 children. Studies reported a worsening of risk parameters for cardiovascular disease in overweight and obese participants. Compared with normal weight children, systolic blood pressure was higher by 4.54 mm Hg (99% confidence interval 2.44 to 6.64; n=12 169, eight studies) in overweight children, and by 7.49 mm Hg (3.36 to 11.62; n=8074, 15 studies) in obese children. We found similar associations between groups in diastolic and 24 h ambulatory systolic blood pressure. Obesity adversely affected concentrations of all blood lipids; total cholesterol and triglycerides were 0.15 mmol/L (0.04 to 0.25, n=5072) and 0.26 mmol/L (0.13 to 0.39, n=5138) higher in obese children, respectively. Fasting insulin and insulin resistance were significantly higher in obese participants but not in overweight participants. Obese children had a significant increase in left ventricular mass of 19.12 g (12.66 to 25.59, n=223), compared with normal weight children.

CONCLUSION

Having a body mass index outside the normal range significantly worsens risk parameters for cardiovascular disease in school aged children. This effect, already substantial in overweight children, increases in obesity and could be larger than previously thought. There is a need to establish whether acceptable parameter cut-off levels not considering weight are a valid measure of risk in modern children and whether methods used in their study and reporting should be standardised.

Neurogenic Hypertension in the Rat

Several techniques of radical denervation of the sino-aortic depressor areas were tried in order to produce a permanent neurogenic hypertension in the rat. The aortic depressor fibers were interrupted at the neck level by resecting the nerves which usually exhibit baroreceptor activity, namely, isolated aortic nerve, sympathetic, and laryngeal nerves. The carotid sinus was denervated by stripping the carotid bifurcation and painting with phenol. When the carotid bifurcation was resected bilaterally, in a one-stage operation, all rats showed symptoms of cerebral ischemia, dying shortly thereafter.

Isolated denervation of the aortic baroreceptors was followed by a transitory hypertension. No changes in preasure were observed when only the carotid sinuses were denervated. A few rats in which the usual baroreceptor pathways were interrupted, except the superior laryngeal nerve, developed chronic hypertension. Yet, to obtain consistently permanent hypertension it was necessary to include in the denervation every baroreceptor route.

A simple one-stage operation for complete sino-aortic baroreceptor denervation is described. This procedure was used in 140 rats that were then studied for periods up to one year. All the operated animals presented some degree of hypertension. Blood pressure measurements made during the first week showed even then that the rats were hypertensive. This observation suggests that in the rat no latent period for the appearance of neurogenic hypertension is present. Hypertension was permanent in 75% of the rats observed up to one year; blood pressure returned to normal values in the remaining 25%, usually after the third month. Extirpation of the adrenal medulla had no effect on the evolution of the hypertension in the denervated rats.

Blood pressure was measured repeatedly in unanesthetized rats by tail plethysmography. Pressure values determined by this method, though 10 to 20 mm Hg lower, approximated the mean arterial pressure recorded directly from the femoral artery in normotensive and hypertensive rats. The hypertension in denervated rats included an increase of systolic as well as diastolic pressure. The heart rates of quiet hypertensive rats were within the normal range and, in general, no close correlation was observed between increases in blood pressure and elevations in heart rate. Normal rats have marked fluctuations in both pressure and heart rate when walking or when stimulated; these fluctuations were much greater in the neurogenic hypertensive animals. Moreover, the hypertensive rats showed large oscillations of blood pressure synchronous with respiratory movements particularly when the latter were slower and deeper than normal.

The rats seemed to tolerate both the denervation and the hypertension very well. Histological examination of tissues from hypertensive rats showed myocardial hypertrophy and a thickening of the basement membrane of the glomerular capsule. The severity of the latter abnormality was closely associated with the duration of the hypertension.

Obesity, Adipose Tissue and Vascular Dysfunction

Cardiovascular diseases are the leading cause of death worldwide. Overweight and obesity are strongly associated with comorbidities such as hypertension and insulin resistance, which collectively contribute to the development of cardiovascular diseases and resultant morbidity and mortality. Forty-two percent of adults in the United States are obese, and a total of 1.9 billion adults worldwide are overweight or obese. These alarming numbers, which continue to climb, represent a major health and economic burden. Adipose tissue is a highly dynamic organ that can be classified based on the cellular composition of different depots and their distinct anatomical localization. Massive expansion and remodeling of adipose tissue during obesity differentially affects specific adipose tissue depots and significantly contributes to vascular dysfunction and cardiovascular diseases. Visceral adipose tissue accumulation results in increased immune cell infiltration and secretion of vasoconstrictor mediators, whereas expansion of subcutaneous adipose tissue is less harmful. Therefore, fat distribution more than overall body weight is a key determinant of the risk for cardiovascular diseases. Thermogenic brown and beige adipose tissue, in contrast to white adipose tissue, is associated with beneficial effects on the vasculature. The relationship between the type of adipose tissue and its influence on vascular function becomes particularly evident in the context of the heterogenous phenotype of perivascular adipose tissue that is strongly location dependent. In this review, we address the abnormal remodeling of specific adipose tissue depots during obesity and how this critically contributes to the development of hypertension, endothelial dysfunction, and vascular stiffness. We also discuss the local and systemic roles of adipose tissue derived secreted factors and increased systemic inflammation during obesity and highlight their detrimental impact on cardiovascular health.

The risk of acute renal failure in patients with chronic kidney disease

Few studies have defined how the risk of hospital-acquired acute renal failure varies with the level of estimated glomerular filtration rate (GFR). It is also not clear whether common factors such as diabetes mellitus, hypertension and proteinuria increase the risk of nosocomial acute renal failure independent of GFR. To determine this we compared 1,746 hospitalized adult members of Kaiser Permanente Northern California who developed dialysis-requiring acute renal failure with 600,820 hospitalized members who did not. Patient GFR was estimated from the most recent outpatient serum creatinine measurement prior to admission. The adjusted odds ratios were significantly and progressively elevated from 1.95 to 40.07 for stage 3 through stage 5 patients (not yet on maintenance dialysis) compared to patients with estimated GFR in the stage 1 and 2 range. Similar associations were seen after controlling for inpatient risk factors. Pre-admission baseline diabetes mellitus, diagnosed hypertension and known proteinuria were also independent risk factors for acute kidney failure. Our study shows that the propensity to develop in-hospital acute kidney failure is another complication of chronic kidney disease whose risk markedly increases even in the upper half of stage 3 estimated GFR. Several common risk factors for chronic kidney disease also increase the peril of nosocomial acute kidney failure.

Hypertriglyceridemia, insulin resistance, and the metabolic syndrome

The metabolic syndrome consists of a cluster of metabolic disorders, many of which promote the development of atherosclerosis and increase the risk of cardiovascular disease events. Insulin resistance may lie at the heart of the metabolic syndrome. Elevated serum triglycerides commonly associate with insulin resistance and represent a valuable clinical marker of the metabolic syndrome. Abdominal obesity is a clinical marker for insulin resistance. The metabolic syndrome manifests 4 categories of abnormality: atherogenic dyslipidemia (elevated triglycerides, increased small low-density lipoproteins, and decreased high-density lipoproteins), increased blood pressure, elevated plasma glucose, and a prothrombotic state. Various therapeutic approaches for the patient with the metabolic syndrome should be implemented to decrease the risk of cardiovascular disease events. These interventions include decreasing obesity, increasing physical activity, and managing dyslipidemia; the latter may require the use of pharmacotherapy with cholesterol-lowering and triglyceride-lowering drugs.

Mendelian randomization with a binary exposure variable: interpretation and presentation of causal estimates

Mendelian randomization uses genetic variants to make causal inferences about a modifiable exposure. Subject to a genetic variant satisfying the instrumental variable assumptions, an association between the variant and outcome implies a causal effect of the exposure on the outcome. Complications arise with a binary exposure that is a dichotomization of a continuous risk factor (for example, hypertension is a dichotomization of blood pressure). This can lead to violation of the exclusion restriction assumption: the genetic variant can influence the outcome via the continuous risk factor even if the binary exposure does not change. Provided the instrumental variable assumptions are satisfied for the underlying continuous risk factor, causal inferences for the binary exposure are valid for the continuous risk factor. Causal estimates for the binary exposure assume the causal effect is a stepwise function at the point of dichotomization. Even then, estimation requires further parametric assumptions. Under monotonicity, the causal estimate represents the average causal effect in 'compliers', individuals for whom the binary exposure would be present if they have the genetic variant and absent otherwise. Unlike in randomized trials, genetic compliers are unlikely to be a large or representative subgroup of the population. Under homogeneity, the causal effect of the exposure on the outcome is assumed constant in all individuals; rarely a plausible assumption. We here provide methods for causal estimation with a binary exposure (although subject to all the above caveats). Mendelian randomization investigations with a dichotomized binary exposure should be conceptualized in terms of an underlying continuous variable.