Functional consequences of the first reported mutations of the proto-oncogene PTTG1IP/PBF.

Pituitary tumor-transforming gene 1-binding factor (PTTG1IP; PBF) is a multifunctional glycoprotein, which is overexpressed in a wide range of tumours, and significantly associated with poorer oncological outcomes, such as early tumour recurrence, distant metastasis, extramural vascular invasion and decreased disease-specific survival. PBF transforms NIH 3T3 fibroblasts and induces tumours in nude mice, while mice harbouring transgenic thyroidal PBF expression show hyperplasia and macrofollicular lesions. Our assumption that PBF becomes an oncogene purely through increased expression has been challenged by the recent report of mutations in PBF within the Catalogue of Somatic Mutations in Cancer (COSMIC) database. We therefore sought to determine whether the first 10 PBF missense substitutions in human cancer might be oncogenic. Anisomycin half-life studies revealed that most mutations were associated with reduced protein stability compared to wild-type (WT) PBF. Proliferation assays narrowed our interest to two mutational events which significantly altered cell turnover: C51R and R140W. C51R was mainly confined to the endoplasmic reticulum while R140W was apparent in the Golgi apparatus. Both C51R and R140W lost the capacity to induce cellular migration and significantly reduced cell invasion. Colony formation and soft agar assays demonstrated that, in contrast to WT PBF, both mutants were unable to elicit significant colony formation or anchorage-independent growth. However, C51R and R140W retained the ability to repress radioiodide uptake, a functional hallmark of PBF. Our data reveal new insight into PBF function and confirm that, rather than being oncogenic, mutations in PBF are likely to be passenger effects, with overexpression of PBF the more important aetiological event in human cancer.

Elevated PTTG and PBF predicts poor patient outcome and modulates DNA damage response genes in thyroid cancer.

The proto-oncogene PTTG and its binding partner PBF have been widely studied in multiple cancer types, particularly thyroid and colorectal, but their combined role in tumourigenesis is uncharacterised. Here, we show for the first time that together PTTG and PBF significantly modulate DNA damage response (DDR) genes, including p53 target genes, required to maintain genomic integrity in thyroid cells. Critically, DDR genes were extensively repressed in primary thyrocytes from a bitransgenic murine model (Bi-Tg) of thyroid-specific PBF and PTTG overexpression. Irradiation exposure to amplify p53 levels further induced significant repression of DDR genes in Bi-Tg thyrocytes (P=2.4 × 10-4) compared with either PBF- (P=1.5 × 10-3) or PTTG-expressing thyrocytes (P=NS). Consistent with this, genetic instability was greatest in Bi-Tg thyrocytes with a mean genetic instability (GI) index of 35.8±2.6%, as well as significant induction of gross chromosomal aberrations in thyroidal TPC-1 cells following overexpression of PBF and PTTG. We extended our findings to human thyroid cancer using TCGA data sets (n=322) and found striking correlations with PBF and PTTG expression in well-characterised DDR gene panel RNA-seq data. In addition, genetic associations and transient transfection identified PBF as a downstream target of the receptor tyrosine kinase-BRAF signalling pathway, emphasising a role for PBF as a novel component in a pathway well described to drive neoplastic growth. We also showed that overall survival (P=1.91 × 10-5) and disease-free survival (P=4.9 × 10-5) was poorer for TCGA patients with elevated tumoural PBF/PTTG expression and mutationally activated BRAF. Together our findings indicate that PBF and PTTG have a critical role in promoting thyroid cancer that is predictive of poorer patient outcome.

Manipulation of PBF/PTTG1IP phosphorylation status; a potential new therapeutic strategy for improving radioiodine uptake in thyroid and other tumors.

CONTEXT: The clinical effectiveness of ablative radioiodine treatment of thyroid tumors is limited by the availability of the sodium iodide symporter (NIS) at the plasma membrane (PM) for uptake of ¹³¹I. A significant proportion of well-differentiated thyroid tumors are unable to concentrate sufficient radioiodine for effective therapy, and in other tumor models such as breast tumors, where radioiodine uptake would be an attractive therapeutic option, uptake is insufficient. OBJECTIVE: Pituitary tumor-transforming gene-binding factor (PBF; PTTG1IP) is overexpressed in multiple cancers and significantly decreases NIS expression at the PM. The goal of this study was to identify a method by which PBF repression of NIS may be overcome in human tumors. RESULTS: Here, we identify PBF as a tyrosine phosphoprotein that specifically binds the proto-oncogene tyrosine protein kinase Src in mass spectrometry, glutathione S-transferase pulldown and coimmunoprecipitation assays. Src induction leads to phosphorylation at PBF residue Y174. Abrogation of this residue results in PM retention and a markedly reduced ability to bind NIS. The Src inhibitor PP1 inhibits PBF phosphorylation in multiple cell lines in vitro, including human primary thyroid cells. Of direct clinical importance to the treatment of thyroid cancer, PP1 stimulates iodide uptake by transfected NIS in TPC1 thyroid carcinoma cells and entirely overcomes PBF repression of iodide uptake in human primary thyroid cells. CONCLUSIONS: We propose that targeting PBF phosphorylation at residue Y174 via tyrosine kinase inhibitors may be a novel therapeutic strategy to enhance the efficacy of ablative radioiodine treatment in thyroid and other endocrine and endocrine-related tumors.

The pituitary tumor transforming gene in thyroid cancer.

The pituitary tumor transforming gene (PTTG) is a multifunctional proto-oncogene that is over-expressed in various tumors including thyroid carcinomas, where it is a prognostic indicator of tumor recurrence. PTTG has potent transforming capabilities in vitro and in vivo, and many studies have investigated the potential mechanisms by which PTTG contributes to tumorigenesis. As the human securin, PTTG is involved in critical mechanisms of cell cycle regulation, whereby aberrant expression induces aneuploidy. PTTG may further contribute to tumorigenesis through its role in DNA damage response pathways and via complex interactions with hormones and growth factors. Furthermore, PTTG over-expression negatively impacts upon the efficacy of radioiodine therapy in thyroid cancer, through repression of expression and function of the sodium iodide symporter. Given its various roles at all disease stages, PTTG appears to be an important oncogene in thyroid cancer. This review discusses the current knowledge of PTTG with particular focus on its role in thyroid cancer.

PTTG-binding factor (PBF) is a novel regulator of the thyroid hormone transporter MCT8.

Within the basolateral membrane of thyroid follicular epithelial cells, two transporter proteins are central to thyroid hormone (TH) biosynthesis and secretion. The sodium iodide symporter (NIS) delivers iodide from the bloodstream into the thyroid, and after TH biosynthesis, monocarboxylate transporter 8 (MCT8) mediates TH secretion from the thyroid gland. Pituitary tumor-transforming gene-binding factor (PBF; PTTG1IP) is a protooncogene that is up-regulated in thyroid cancer and that binds NIS and modulates its subcellular localization and function. We now show that PBF binds MCT8 in vitro, eliciting a marked shift in MCT8 subcellular localization and resulting in a significant reduction in the amount of MCT8 at the plasma membrane as determined by cell surface biotinylation assays. Colocalization and interaction between PBF and Mct8 was also observed in vivo in a mouse model of thyroid-specific PBF overexpression driven by a bovine thyroglobulin (Tg) promoter (PBF-Tg). Thyroidal Mct8 mRNA and protein expression levels were similar to wild-type mice. Critically, however, PBF-Tg mice demonstrated significantly enhanced thyroidal TH accumulation and reduced TH secretion upon TSH stimulation. Importantly, Mct8-knockout mice share this phenotype. These data show that PBF binds and alters the subcellular localization of MCT8 in vitro, with PBF overexpression leading to an accumulation of TH within the thyroid in vivo. Overall, these studies identify PBF as the first protein to interact with the critical TH transporter MCT8 and modulate its function in vivo. Furthermore, alongside NIS repression, PBF may thus represent a new regulator of TH biosynthesis and secretion.

Monocarboxylate transporter 8 in neuronal cell growth.

Thyroid hormones are essential for the normal growth and development of the fetus, and even small alterations in maternal thyroid hormone status during early pregnancy may be associated with neurodevelopmental abnormalities in childhood. Mutations in the novel and specific thyroid hormone transporter monocarboxylate transporter 8 (MCT8) have been associated with severe neurodevelopmental impairment. However, the mechanism by which MCT8 influences neural development remains poorly defined. We have therefore investigated the effect of wild-type (WT) MCT8, and the previously reported L471P mutant, on the growth and function of human neuronal precursor NT2 cells as well as MCT8-null JEG-3 cells. HA-tagged WT MCT8 correctly localized to the plasma membrane in NT2 cells and increased T(3) uptake in both cell types. In contrast, L471P MCT8 was largely retained in the endoplasmic reticulum and displayed no T(3) transport activity. Transient overexpression of WT and mutant MCT8 proteins failed to induce endoplasmic reticular stress or apoptosis. However, MCT8 overexpression significantly repressed cell proliferation in each cell type in both the presence and absence of the active thyroid hormone T(3) and in a dose-dependent manner. In contrast, L471P MCT8 showed no such influence. Finally, small interfering RNA depletion of endogenous MCT8 resulted in increased cell survival and decreased T(3) uptake. Given that T(3) stimulated proliferation in embryonic neuronal NT2 cells, whereas MCT8 repressed cell growth, these data suggest an entirely novel role for MCT8 in addition to T(3) transport, mediated through the modulation of cell proliferation in the developing brain.

PTTG and PBF repress the human sodium iodide symporter.

The ability of the thyroid to accumulate iodide provides the basis for radioiodine ablation of differentiated thyroid cancers and their metastases. Most thyroid tumours exhibit reduced iodide uptake, although the mechanisms accounting for this remain poorly understood. Pituitary tumour transforming gene (PTTG) is a proto-oncogene implicated in the pathogenesis of thyroid tumours. We now show that PTTG and its binding factor PBF repress expression of sodium iodide symporter (NIS) messenger RNA (mRNA), and inhibit iodide uptake. This process is mediated at least in part through fibroblast growth factor-2. In detailed studies of the NIS promoter in rat FRTL-5 cells, PTTG and PBF demonstrated specific inhibition of promoter activity via the human upstream enhancer element (hNUE). Within this approximately 1 kb element, a complex PAX8-upstream stimulating factor 1 (USF1) response element proved critical both to basal promoter activity and to PTTG and PBF repression of NIS. In particular, repression by PTTG was contingent upon the USF1, but not the PAX8, site. Finally, in human primary thyroid cells, PTTG and PBF similarly repressed the NIS promoter via hNUE. Taken together, our data suggest that the reported overexpression of PTTG and PBF in differentiated thyroid cancer has profound implications for activity of the NIS gene, and hence significantly impacts upon the efficacy of radioiodine treatment.

Securin induces genetic instability in colorectal cancer by inhibiting double-stranded DNA repair activity.

Genetic instability (GI) is a hallmark feature of tumor development. Securin, also known as pituitary tumor transforming gene (PTTG), is a mitotic checkpoint protein which is highly expressed in numerous cancers, is associated with tumor invasiveness, and induces GI in thyroid cells. We used fluorescence inter-simple sequence repeat PCR to assess GI caused primarily by DNA breakage events in 19 colorectal tumors. GI values ranged significantly, with Dukes' stage C&D colorectal tumors exhibiting greater GI and higher securin expression than Dukes' stage A&B tumors. Consistent with these findings, we observed a dose-dependent increase in GI in HCT116 cells in response to securin overexpression, as well as in non-transformed human fibroblasts. As securin has been implicated in a novel DNA repair pathway in fission yeast, we investigated its potential role in chemotoxic DNA damage response pathways in mammalian cells, using host cell reactivation assays. Securin overexpression in HCT116 cells inhibited etoposide-induced double-stranded DNA damage repair activity, and repressed Ku heterodimer function. Additionally, we observed that securin and Ku70 showed a reciprocal cytosol-nuclear translocation in response to etoposide-induced dsDNA damage. Our data suggest that, by repressing Ku70 activity and inhibiting the non-homologous end-joining dsDNA repair pathway, securin may be a critical gene in the development of GI in colorectal cancer.

M-mode echocardiographic predictors of six- to seven-year incidence of coronary heart disease, stroke, congestive heart failure, and mortality in an elderly cohort (the Cardiovascular Health Study).

Previous studies have identified a number of echocardiographic variables that predict cardiovascular disease (CVD) events and mortality, but have not focused on a large elderly cohort. The purpose of this study was to determine whether M-mode echocardiographic variables predicted all-cause mortality, incident coronary heart disease (CHD), congestive heart failure (CHF), and stroke in a large prospective, multicenter, population-based study. In the Cardiovascular Health Study, a biracial cohort of 5,888 men and women (mean age 73 years) underwent 2-dimensional M-mode echocardiographic measurements of left ventricular (LV) internal dimensions, wall thickness, mass and geometry, as well as measurement of left atrial dimension and assessment for mitral annular calcium. Participants were followed for 6 to 7 years for incident events; analyses excluded subjects with prevalent disease. One or more echocardiographic measurements were independent predictors of all-cause mortality and incident CHD, CHF, and stroke. After adjustment for anthropometric and traditional CVD risk factors, LV mass was significantly related to incident CHD, CHF, and stroke. The highest quartile of LV mass conferred a hazards ratio of 3.36, compared with the lowest quartile, for incident CHF. Furthermore, incident CHF-free survival was significantly lower for participants with LV mass in the highest versus the 2 lowest quartiles (86% vs 97%, respectively, at 2,500 days). Eccentric and concentric LV hypertrophy, respectively, conferred adjusted hazards ratios, compared with normal LV geometry, of 2.05 and 1.61 for incident CHD, and 2.95 and 3.32 for incident CHF. Thus, in an elderly biracial population, selected 2-dimensional M-mode echocardiographic measurements were important markers of subclinical disease and conferred independent prognostic information for incident CVD events, especially CHF and CHD.

Basal and reserve renal artery blood flow: effect of endothelium-dependent and -independent vasoactive agonists and radiographic contrast medium in two patients.

This manuscript describes the results of invasive testing of renal artery and arteriolar reactivity in two patients using a panel of endothelium-dependent and -independent agents including radiographic contrast medium. We found that the renal artery and microcirculation dilate in response to graded acetylcholine infusions and to bolus nitroglycerin infusion; the renal microcirculation dilates in response to papaverine but constricts after adenosine and after radiographic contrast medium. Future indications for this testing are briefly discussed.

Efficacy of live, attenuated, human rotavirus vaccine 89-12 in infants: a randomised placebo-controlled trial.

BACKGROUND: Rotavirus is the most common cause of severe, dehydrating diarrhoea in infants worldwide. We assessed the safety, immunogenicity, and efficacy of a live, oral human rotavirus vaccine, 89-12, in US children in a randomised, placebo-controlled, double-blind multicentre trial. METHODS: 215 healthy infants were enrolled, of whom 213 were given two doses of 89-12 (containing 1x10(5) plaque-forming units) or placebo, and 213 were followed up through one rotavirus season. The frequency of side-effects was compared for 7 days after each dose of vaccine. Immune responses to rotavirus were assessed by serum and stool IgA, and by serum 89-12 neutralising titres. The primary outcome variable (protection from rotavirus disease) was evaluated by comparing the frequencies of rotavirus gastroenteritis in an intention-to-treat analysis. FINDINGS: Adverse reactions were mild. Low-grade fever (> or = 38.1 degrees C) after the first dose was the only side-effect significantly more common in the vaccine group than in the placebo group (21 [19%] vs 5 [5%], p=0.001). An immune response to vaccine was detected in 94.4% of vaccinees. Rotavirus disease occurred in 18 of 107 placebo recipients and two of 108 vaccine recipients (vaccine efficacy 89.0% [95% CI 65.4-94.5]). Ten infants in the placebo group but none in the vaccine group were presented for medical care. INTERPRETATION: The 89-12 rotavirus vaccine was safe and immunogenic and provided a high degree of protection against rotavirus disease. Further investigations of this vaccine are needed to confirm these findings in other settings.

Left ventricular diastolic filling in the elderly: the cardiovascular health study.

Changes in left ventricular (LV) diastolic function (e.g., as measured by transmitral flow velocity) are known to occur with aging. In addition, impaired LV diastolic function plays an important role in such cardiovascular disorders common in the elderly as hypertension, ischemic heart disease, and congestive heart failure (CHF). Participants in the Cardiovascular Health Study, a multicenter study of community-dwelling men (n=2,239) and women (n=2,962) > or = 65 years of age, underwent an extensive baseline evaluation, including echocardiography. Early diastolic LV Doppler (transmitral) peak filling velocity decreased, and peak late diastolic (atrial) velocity increased with age in multivariate analyses (all p <0.001). Early and late diastolic peak filling velocities were both significantly higher in women than in men, even after adjustment for body surface area (or height and weight). In multivariate models in the entire cohort and a healthy subgroup (n=703), gender, age, heart rate, and blood pressure (BP) were most strongly related to early and late diastolic transmitral peak velocities. Early and late diastolic peak velocities both increased with increases in systolic BP and decreased with increases in diastolic BP (p <0.001). Doppler transmitral velocities were compared among health status subgroups. In multiple regression models adjusted for other covariates, and in analysis of variance models examining differences across subgroups adjusted only for age, the subgroup with CHF had the highest early diastolic peak velocities. All clinical disease subgroups had higher late diastolic peak velocities than the healthy subgroup, with the subgroups with either CHF or hypertension having the highest age-adjusted means. The subgroup with hypertension had the lowest ratio of early-to-late diastolic peak velocity, and men with CHF had the highest ratio. These findings are consistent with previous reports that hypertensive subjects exhibit an abnormal relaxation pattern, whereas patients with CHF develop a pattern suggestive of an increased early diastolic left atrial-LV pressure gradient.

Safety and immunogenicity of live, attenuated human rotavirus vaccine 89-12.

The safety and immunogenicity of an orally administered live human rotavirus vaccine candidate (89-12), attenuated by 33 passages in monkey kidney cells, were evaluated in placebo-controlled trials in adults, children and infants. This strain was selected because natural infections with 89-12-like rotaviruses provided 100% protection over two years. The initial evaluations in adults, seropositive children and nine infants indicated that the vaccine was safe. Two doses of vaccine (10(5) p.f.u. dose-1) or placebo were then given to 42 infants, aged from 6 to 26 weeks. No significant difference in side effects was seen. Seroconversion was demonstrated in 19 of 20 previously uninfected vaccine recipients, but > or = 4-fold rises in 89-12 neutralizing antibody titers were detected in only seven subjects. Intestinal IgA responses were detected in 15 subjects. This attenuated human rotavirus was safe and immunogenic and should be further evaluated as a vaccine candidate.

Attenuation of a human rotavirus vaccine candidate did not correlate with mutations in the NSP4 protein gene.

The NSP4 protein of a simian rotavirus was reported to induce diarrhea following inoculation of mice. If NSP4 is responsible for rotavirus diarrhea in humans, attenuation of a human rotavirus may be reflected in concomitant mutations in the NSP4 gene. After 33 passages in cultured monkey kidney cells, a virulent human rotavirus (strain 89-12) was found to be attenuated in adults, children, and infants. Nucleotide sequence analysis of the NSP4 protein gene revealed only one base pair change between the virulent (unpassaged) and attenuated 89-12 viruses, which resulted from a substitution of alanine for threonine at amino acid 45 of the encoded NSP4 protein. Because both threonine and alanine have been found at position 45 of NSP4 in symptomatic and asymptomatic human rotaviruses, neither amino acid in this position could be established as a marker of virulence. Therefore, attenuation of rotavirus strain 89-12 appears to be unrelated to mutations in the NSP4 gene.

Coronary vasomotor reactivity among normotensive African and white American subjects with chest pain.

BACKGROUND AND OBJECTIVES: Excess cardiovascular morbidity and mortality among African (black) Americans is the subject of intensive investigation but the etiology remains speculative. One hypothesis proposes that inherent, or intrinsic, differences in coronary vascular reactivity and endothelial function predispose African Americans to enhanced vasoconstriction and/or depressed vasodilation, resulting in excess ischemia. The objective of this study was to establish whether coronary vasoreactivity differs among normotensive, nondiabetic African and white Americans with normal arteries referred for coronary arteriography because of chest pain. PATIENTS AND METHODS: Eleven African American (8 female, 3 male) and 28 white American (9 female, 19 male) normotensive, euglycemic patients with normal coronary arteries were prospectively recruited for invasive testing of coronary artery and microvascular relaxation using the endothelium-dependent and -independent agents, acetylcholine and adenosine; a Doppler tipped intracoronary guidewire; and quantitative coronary angiography. RESULTS: The study cohort consisted of 17 women (44%) and 22 men (56%) with a mean age of 46 +/- 10 yrs. Of 8 African American women, 6 were premenopausal and 2 were postmenopausal on estrogen replacement therapy. Of 9 white American women, 2 were premenopausal, 1 was 46-year old with a previous history of hysterectomy without ovariectomy, 2 were postmenopausal on estrogen replacement therapy, 2 were perimenopausal and 44- and 54-year old, and 2 were postmenopausal without estrogen replacement therapy. In response to maximal infusion of acetylcholine, epicardial coronary arteries and resistance vessels dilated similarly in black and white subjects. Dose-response curves revealed no significant racial differences during submaximal graded infusion of acetylcholine. In response to peak effect of adenosine, there were no racial differences in dilation of the microcirculation. CONCLUSIONS: In the absence of hypertension, diabetes mellitus, and angiographic evidence of coronary artery disease, African American women demonstrate no evidence of intrinsic predisposition to enhanced coronary conduit vasoconstriction or depressed microcirculatory dilation in response to the endothelium-dependent and -independent vasodilator agonists-acetylcholine and adenosine-when compared with responses of similar white men and women. Because of low enrollment of black males, definitive conclusions cannot be drawn regarding this group.

Clinical factors associated with calcific aortic valve disease. Cardiovascular Health Study.

OBJECTIVES: The aim of this study was to determine the prevalence of aortic sclerosis and stenosis in the elderly and to identify clinical factors associated with degenerative aortic valve disease. BACKGROUND: Several lines of evidence suggest that degenerative aortic valve disease is not an inevitable consequence of aging and may be associated with specific clinical factors. METHODS: In 5,201 subjects > or = 65 years of age enrolled in the Cardiovascular Health Study, the relation between aortic sclerosis or stenosis identified on echocardiography and clinical risk factors for atherosclerosis was evaluated by using stepwise logistic regression analysis. RESULTS: Aortic valve sclerosis was present in 26% and aortic valve stenosis in 2% of the entire study cohort; in subjects > or = 75 years of age, sclerosis was present in 37% and stenosis in 2.6%. Independent clinical factors associated with degenerative aortic valve disease included age (twofold increased risk for each 10-year increase in age), male gender (twofold excess risk), present smoking (35% increase in risk) and a history of hypertension (20% increase in risk). Other significant factors included height and high lipoprotein(a) and low density lipoprotein cholesterol levels. CONCLUSIONS: Clinical factors associated with aortic sclerosis and stenosis can be identified and are similar to risk factors for atherosclerosis.

Effect of African-American race and hypertensive left ventricular hypertrophy on coronary vascular reactivity and endothelial function.

Excess cardiovascular morbidity and mortality among African (black) Americans remains an important yet unexplained public health problem. One possible explanation proposes that intrinsic or acquired abnormalities in coronary vascular reactivity and endothelial function result in excess ischemia among black Americans. To examine this hypothesis, we subjected 80 individuals with normal coronary arteries to invasive testing of coronary artery and microvascular relaxation using intracoronary infusions of acetylcholine and adenosine, a Doppler tipped intracoronary guide wire, and quantitative coronary angiography. We measured the percent increase in coronary blood flow and epicardial diameter after graded infusion of intracoronary acetylcholine and in coronary blood flow after intracoronary adenosine in 31 normotensive subjects (10 black, 21 white) and 49 hypertensive subjects with left ventricular hypertrophy (25 black, 24 white). Categorical and multivariate analyses revealed that in response to intracoronary adenosine and acetylcholine, the depression in endothelium-independent and -dependent microvascular relaxation during peak agonist effect was largely related to the presence of chronic hypertension and left ventricular hypertrophy. Normotensive subjects demonstrated no intrinsic racial differences in conduit and resistance vessel vasoreactivity. In response to maximal infusion of acetylcholine, epicardial coronary arteries constricted similarly in black and white subjects with hypertensive left ventricular hypertrophy and dilated similarly in normotensive black and white subjects. Thus, our study shows that in a cohort of black and white subjects referred for coronary arteriography because of chest pain, African American race is not associated with excess intrinsic or acquired depression in coronary vascular relaxation during the peak effect of the endothelium-dependent and -independent agonists acetylcholine and adenosine, after adjustment for the presence of left ventricular hypertrophy.

Diabetes mellitus and echocardiographic left ventricular function in free-living elderly men and women: The Cardiovascular Health Study.

This report describes the relation among diabetes, blood pressure, and prevalent cardiovascular disease, and echocardiographically measured left ventricular mass and filling (transmitral valve flow) velocities in the Cardiovascular Health Study, a cohort of 5201 men and women > or = 65 years of age. Ventricular septal and left posterior wall thicknesses were greater in diabetic than in nondiabetic subjects, showing a significant linear trend (p = 0.025 for ventricular septal thickness in both sexes combined, p = 0.002 for posterior wall thickness) with increased duration of diabetes. Increased wall thickness of the ventricular septum or the left posterior wall was not associated with prevalent coronary heart disease (CHD) in the cohort. Increased left ventricular mass was associated with diabetic persons not reporting CHD and with all subjects with CHD regardless of glucose tolerance status. After adjusting for body weight, blood pressure, heart rate, and prevalent coronary or cerebrovascular disease, diabetes (as measured by glucose level, insulin use, oral hypoglycemic use, and a positive history of diabetes before baseline examination) remained an independent predictor of increased left ventricular mass among men and women (174.2 gm in diabetic men vs 169.8 gm in normal men, 138.2 gm in diabetic women vs 134.0 gm in normal women, p = 0.043 for both sexes combined). Both early and late diastolic transmitral peak flow velocities were higher with increased duration of diabetes, but the calculated ratio of the early peak flow velocity to the late velocity (E/A ratio) did not differ significantly between subjects with historical diabetes and those with normal fasting glucose (both genders combined, p = 0.190). Glucose level, insulin use, oral hypoglycemic use, and a positive history of diabetes before baseline examination were significant independent predictors of the late transmitral peak flow velocity and its integrated flow-velocity curve but not for the integral of the early peak flow velocity or the E/A ratio. Diabetes is associated with abnormal left ventricular structure and function in elderly persons. This association persists after adjustment for body weight, blood pressure, heart rate, and reported coronary or cerebrovascular disease.

Coronary vasomotor function in a normotensive, nondiabetic referral population with normal coronary arteriograms.

In a referral normal cardiac population, endothelium-independent coronary relaxation is nearly always normal, but endothelium-dependent relaxation may be depressed in a significant proportion of patients. Further study of the natural history of referral subjects with endothelial dysfunction is necessary to assess the potential cardiovascular risk of this finding in a presumed low-risk population.