Fatty acid synthesis suppresses dietary polyunsaturated fatty acid use

Dietary polyunsaturated fatty acids (PUFA) are increasingly recognized for their health benefits, whereas a high production of endogenous fatty acids - a process called de novo lipogenesis (DNL) - is closely linked to metabolic diseases. Determinants of PUFA incorporation into complex lipids are insufficiently understood and may influence the onset and progression of metabolic diseases. Here we show that fatty acid synthase (FASN), the key enzyme of DNL, critically determines the use of dietary PUFA in mice and humans. Moreover, the combination of FASN inhibition and PUFA-supplementation decreases liver triacylglycerols (TAG) in mice fed with high-fat diet. Mechanistically, FASN inhibition causes higher PUFA uptake via the lysophosphatidylcholine transporter MFSD2A, and a diacylglycerol O-acyltransferase 2 (DGAT2)-dependent incorporation of PUFA into TAG. Overall, the outcome of PUFA supplementation may depend on the degree of endogenous DNL and combining PUFA supplementation and FASN inhibition might be a promising approach to target metabolic disease.

Loss of hepatic SMLR1 causes hepatosteatosis and protects against atherosclerosis due to decreased hepatic VLDL secretion

BACKGROUND AND AIMS

The assembly and secretion of VLDL from the liver, a pathway that affects hepatic and plasma lipids, remains incompletely understood. We set out to identify players in the VLDL biogenesis pathway by identifying genes that are co-expressed with the MTTP gene that encodes for microsomal triglyceride transfer protein, key to the lipidation of apolipoprotein B, the core protein of VLDL. Using human and murine transcriptomic data sets, we identified small leucine-rich protein 1 ( SMLR1 ), encoding for small leucine-rich protein 1, a protein of unknown function that is exclusively expressed in liver and small intestine.

APPROACH AND RESULTS

To assess the role of SMLR1 in the liver, we used somatic CRISPR/CRISPR-associated protein 9 gene editing to silence murine Smlr1 in hepatocytes ( Smlr1 -LKO). When fed a chow diet, male and female mice show hepatic steatosis, reduced plasma apolipoprotein B and triglycerides, and reduced VLDL secretion without affecting microsomal triglyceride transfer protein activity. Immunofluorescence studies show that SMLR1 is in the endoplasmic reticulum and Cis-Golgi complex. The loss of hepatic SMLR1 in female mice protects against diet-induced hyperlipidemia and atherosclerosis but causes NASH. On a high-fat, high-cholesterol diet, insulin and glucose tolerance tests did not reveal differences in male Smlr1 -LKO mice versus controls.

CONCLUSIONS

We propose a role for SMLR1 in the trafficking of VLDL from the endoplasmic reticulum to the Cis-Golgi complex. While this study uncovers SMLR1 as a player in the VLDL assembly, trafficking, and secretion pathway, it also shows that NASH can occur with undisturbed glucose homeostasis and atheroprotection.

Lipidome Analysis of Oropharyngeal Tumor Tissues Using Nanosecond Infrared Laser (NIRL) Tissue Sampling and Subsequent Mass Spectrometry

Ultrashort pulse infrared lasers can simultaneously sample and homogenize biological tissue using desorption by impulsive vibrational excitation (DIVE). With growing attention on alterations in lipid metabolism in malignant disease, mass spectrometry (MS)-based lipidomic analysis has become an emerging topic in cancer research. In this pilot study, we investigated the feasibility of tissue sampling with a nanosecond infrared laser (NIRL) for the subsequent lipidomic analysis of oropharyngeal tissues, and its potential to discriminate oropharyngeal squamous cell carcinoma (OPSCC) from non-tumorous oropharyngeal tissue. Eleven fresh frozen oropharyngeal tissue samples were ablated. The produced aerosols were collected by a glass fiber filter, and the lipidomes were analyzed with mass spectrometry. Data was evaluated by principal component analysis and Welch's t-tests. Lipid profiles comprised 13 lipid classes and up to 755 lipid species. We found significant inter- and intrapatient alterations in lipid profiles for tumor and non-tumor samples (p-value < 0.05, two-fold difference). Thus, NIRL tissue sampling with consecutive MS lipidomic analysis is a feasible and promising approach for the differentiation of OPSCC and non-tumorous oropharyngeal tissue and may provide new insights into lipid composition alterations in OPSCC.

Diagnostic potential of extracellular vesicles in meningioma patients

BACKGROUND

Extracellular vesicles (EVs) play an important role in cell-cell communication, and tumor-derived EVs circulating in patient blood can serve as biomarkers. Here, we investigated the potential role of plasma EVs in meningioma patients for tumor detection and determined whether EVs secreted by meningioma cells reflect epigenetic, genomic, and proteomic alterations of original tumors.

METHODS

EV concentrations were quantified in patient plasma (n = 46). Short-term meningioma cultures were established (n = 26) and secreted EVs were isolated. Methylation and copy number profiling was performed using 850k arrays, and mutations were identified by targeted gene panel sequencing. Differential quantitative mass spectrometry was employed for proteomic analysis.

RESULTS

Levels of circulating EVs were elevated in meningioma patients compared to healthy individuals, and the plasma EV concentration correlated with malignancy grade and extent of peritumoral edema. Postoperatively, EV counts dropped to normal levels, and the magnitude of the postoperative decrease was associated with extent of tumor resection. Methylation profiling of EV-DNA allowed correct tumor classification as meningioma in all investigated cases, and accurate methylation subclass assignment in almost all cases. Copy number variations present in tumors, as well as tumor-specific mutations were faithfully reflected in meningioma EV-DNA. Proteomic EV profiling did not permit original tumor identification but revealed tumor-associated proteins that could potentially be utilized to enrich meningioma EVs from biofluids.

CONCLUSIONS

Elevated EV levels in meningioma patient plasma could aid in tumor diagnosis and assessment of treatment response. Meningioma EV-DNA mirrors genetic and epigenetic tumor alterations and facilitates molecular tumor classification.

Role of Endothelial Cell Lipoprotein Lipase for Brown Adipose Tissue Lipid and Glucose Handling

Cold-induced activation of brown adipose tissue (BAT) has an important impact on systemic lipoprotein metabolism by accelerating the processing of circulating triglyceride-rich lipoproteins (TRL). Lipoprotein lipase (LPL) expressed by adipocytes is translocated via endothelial to the capillary lumen, where LPL acts as the central enzyme for the vascular lipoprotein processing. Based on preliminary data showing that LPL is not only expressed in adipocytes but also in endothelial cells of cold-activated BAT, we aimed to dissect the relevance of endothelial versus adipocyte LPL for lipid and energy metabolism in the context of adaptive thermogenesis. By metabolic studies we found that cold-induced triglyceride uptake into BAT, lipoprotein disposal, glucose uptake and adaptive thermogenesis were not impaired in mice lacking Lpl exclusively in endothelial cells. This finding may be explained by a compensatory upregulation in the expression of adipocyte-derived Lpl and endothelial lipase (Lipg).

Susceptibility to diet-induced obesity at thermoneutral conditions is independent of UCP1

Activation of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) upon cold stimulation leads to substantial increase in energy expenditure to defend body temperature. Increases in energy expenditure after a high-caloric food intake, termed diet-induced thermogenesis, are also attributed to BAT. These properties render BAT a potential target to combat diet-induced obesity. However, studies investigating the role of UCP1 to protect against diet-induced obesity are controversial and rely on the phenotyping of a single constitutive UCP1-knockout model. To address this issue, we generated a novel UCP1-knockout model by Cre-mediated deletion of exon 2 in the UCP1 gene. We studied the effect of constitutive UCP1 knockout on metabolism and the development of diet-induced obesity. UCP1 knockout and wild-type mice were housed at 30°C and fed a control diet for 4 wk followed by 8 wk of high-fat diet. Body weight and food intake were monitored continuously over the course of the study, and indirect calorimetry was used to determine energy expenditure during both feeding periods. Based on Western blot analysis, thermal imaging and noradrenaline test, we confirmed the lack of functional UCP1 in knockout mice. However, body weight gain, food intake, and energy expenditure were not affected by loss of UCP1 function during both feeding periods. We introduce a novel UCP1-KO mouse enabling the generation of conditional UCP1-knockout mice to scrutinize the contribution of UCP1 to energy metabolism in different cell types or life stages. Our results demonstrate that UCP1 does not protect against diet-induced obesity at thermoneutrality.NEW & NOTEWORTHY We provide evidence that the abundance of UCP1 does not influence energy metabolism at thermoneutrality studying a novel Cre-mediated UCP1-KO mouse model. This model will be a foundation for a better understanding of the contribution of UCP1 in different cell types or life stages to energy metabolism.

Genome-wide methylation profiling of glioblastoma cell-derived extracellular vesicle DNA allows tumor classification

BACKGROUND

Genome-wide DNA methylation profiling has recently been developed into a tool that allows tumor classification in central nervous system tumors. Extracellular vesicles (EVs) are released by tumor cells and contain high molecular weight DNA, rendering EVs a potential biomarker source to identify tumor subgroups, stratify patients and monitor therapy by liquid biopsy. We investigated whether the DNA in glioblastoma cell-derived EVs reflects genome-wide tumor methylation and mutational profiles and allows noninvasive tumor subtype classification.

METHODS

DNA was isolated from EVs secreted by glioblastoma cells as well as from matching cultured cells and tumors. EV-DNA was localized and quantified by direct stochastic optical reconstruction microscopy. Methylation and copy number profiling was performed using 850k arrays. Mutations were identified by targeted gene panel sequencing. Proteins were differentially quantified by mass spectrometric proteomics.

RESULTS

Genome-wide methylation profiling of glioblastoma-derived EVs correctly identified the methylation class of the parental cells and original tumors, including the MGMT promoter methylation status. Tumor-specific mutations and copy number variations (CNV) were detected in EV-DNA with high accuracy. Different EV isolation techniques did not affect the methylation profiling and CNV results. DNA was present inside EVs and on the EV surface. Proteome analysis did not allow specific tumor identification or classification but identified tumor-associated proteins that could potentially be useful for enriching tumor-derived circulating EVs from biofluids.

CONCLUSIONS

This study provides proof of principle that EV-DNA reflects the genome-wide methylation, CNV, and mutational status of glioblastoma cells and enables their molecular classification.

Effects of lovastatin and gemfibrozil in subjects with high ratios of total cholesterol to high-density lipoprotein cholesterol

Insulin resistance is associated with hypertriglyceridemia, low serum high-density lipoprotein cholesterol (HDL-C) concentrations and high serum total cholesterol (TC) to HDL-C ratios. Several reports have demonstrated that either lovastatin or gemfibrozil may favorably lower serum lipid concentrations. However, their effects on insulin sensitivity are unknown. The primary aim of this study was to compare the effects of lovastatin and gemfibrozil on insulin sensitivity and serum leptin concentrations in subjects with high TC/HDL-C ratios. We enrolled 25 nondiabetic patients, similar in terms of age and weight with TC/HDL-C ratios greater than 5. Thirteen subjects were treated with lovastatin 20 mg per day, and 12 received gemfibrozil 300 mg twice per day. Plasma lipids, glucose, and leptin were measured, and a 75-g oral glucose tolerance test (OGTT) and a modified insulin suppression test were performed before and after 3 months of treatment. The study showed the mean plasma TC, low-density lipoprotein cholesterol (LDL-C) concentrations, and TC/HDL-C ratio were significantly reduced in the lovastatin-treated group, but no obvious effects on plasma triglyceride (TG) and HDL-C were noted. In the gemfibrozil group, plasma TG and HDL-C were markedly lowered, but no significantly different effects in other plasma lipids were found. Gemfibrozil did not affect steady-state plasma glucose (SSPG) concentrations, whereas lovastatin significantly increased SSPG concentrations. Neither drug affected the serum leptin concentration during the OGTT. We conclude that lovastatin significantly lowers plasma TC and LDL-C ratio, and TC/HDL-C concentrations and adversely affects insulin sensitivity, while gemfibrozil markedly reduces plasma TG concentrations without altering insulin sensitivity in subjects with high TC/HDL-C ratios.

Causes of death and associated factors among patients with non-insulin-dependent diabetes mellitus in Taipei, Taiwan

A cohort of 766 patients with non-insulin-dependent diabetes mellitus (NIDDM) from a general teaching hospital in Taipei, Taiwan were followed prospectively to assess survival experience and associated risk factors. Data were abstracted from the medical records and additional information was obtained from patients or their closest relatives using a structured questionnaire. Date and cause of death were determined from death certificates. Standardized mortality ratios were calculated by the direct method. Chi2-Square test and Cox's proportional hazard analysis were used to control for potential confounders. During a median follow-up of 3.5 years (range 1 month to 4.6 years), 131 deaths occurred. Of these, 29.8% were due to cardiopulmonary disease (ICD 401-429), 13.0% due to cerebrovascular disease (ICD 430-438), 13.0% due to acute diabetes metabolic complications (250.1, 250.2), and 11.4% due to nephropathy (580-589). Adjusted for age, people with NIDDM had 2.2 (95% CI 1.6-2.9) times the risk of death than members of the general population, and cause-specific standardized mortality ratios were: CPD 4.6, nephropathy 8.8, cerebrovascular disease 1.9, and neoplasm 0.7. Age, fasting plasma glucose, hypertension, and proteinuria were positively and independently associated with all-cause mortality (P < 0.05 for each). Thus, NIDDM patients have higher mortality rates than the general population in Taiwan, and age, fasting plasma glucose, hypertension, and proteinuria are associated with this excess risk. Proper application of available interventions may control these factors with a consequent reduction in mortality. Particular attention is needed to prevent deaths from the acute metabolic complications of diabetes.

Insulin resistance in patients with Klinefelter's syndrome and idiopathic gonadotropin deficiency

Patients with Klinefelter's syndrome (KS) have hypergonadotropic hypogonadism and have a higher incidence of diabetes mellitus. Patients with idiopathic gonadotropin deficiency (IGD) also have hypogonadism but have no proven impaired glucose metabolism. Because high serum testosterone concentrations are thought to correlate with insulin resistance, we assessed the relationship of testosterone concentration with insulin resistance in patients with KS or IGD and normal subjects. Seven patients with KS, six with IGD, and seven normal individuals (controls) were enrolled. Insulin resistance was evaluated by two methods: the total area under the curve (AUC) and the incremental AUC of serum insulin concentrations in response to a 75-g oral glucose load, and the insulin suppression test. KS patients had significantly higher follicle-stimulating hormone and luteinizing hormone concentrations than the normal controls, while IGD patients did not. The plasma testosterone concentrations were significantly lower in both KS and IGD groups than in controls. The incremental AUC and total AUC were higher in both KS and IGD patients than in normal subjects. The steady-state plasma glucose concentrations of the KS and IGD groups were significantly higher than that of the normal group, while the steady-state plasma insulin concentrations were similar in all three groups. After log transformation, the plasma testosterone concentration was negatively related to steady-state plasma glucose concentration in all three groups (r = -0.58, p = 0.019). In conclusion, insulin resistance was consistently noted in patients with KS and IGD. Plasma testosterone concentration is inversely related to insulin resistance.

An Asian multicenter clinical trial to assess the efficacy and tolerability of acarbose compared with placebo in type 2 diabetic patients previously treated with diet. Asian Acarbose Study Group

OBJECTIVE

To assess the efficacy, safety, and tolerability of acarbose versus placebo during a 24-week treatment period in Asian type 2 diabetic patients with dietary failure.

RESEARCH DESIGN AND METHODS

After a 6-week screening period, 126 multiethnic Asian type 2 diabetic patients (64 men, 62 women; mean age +/- SD, 53.4 +/- 10 years) were randomized to receive acarbose (n = 63) or placebo (n = 63). The dosage was increased from 50 mg t.i.d. at week 0 to 100 mg t.i.d. at week 4. Patients were then followed up at weeks 10, 16, and 24. At each visit, body weight, blood pressure, and metabolic indexes were measured. At weeks 0 and 24, fasting plasma glucose and insulin were measured before and 1 h after the administration of an individually tailored breakfast.

RESULTS

Using the intention-to-treat analysis, there were greater reductions in (mean [95% CI]) HbA1c (-0.70 [-1.00 to -0.39] vs. -0.27% [-0.54 to 0]; P = 0.04), fasting plasma glucose (-0.37 [-0.75 to 0.02] vs. 0.41 mmol/l [-0.08 to 0.90]; P = 0.017) and 1-h plasma glucose (-0.77 [-1.44 to -0.10] vs. 0.65 mmol/l [-0.07 to 1.36]; P = 0.05) in the acarbose group compared with the placebo group. With acarbose treatment, 78% of patients achieved an HbAlc < 8% compared with 56% in the placebo group (P = 0.003). There was a greater reduction in body weight (-1.31 [-2.46 to -0.15] vs. 0.16 kg [-3.36 to 0.10]; P = 0.02) and higher incidence of flatulence (56 vs. 37%; P = 0.032) in the acarbose than in the placebo group. Using baseline HbA1c and race as covariates, there were no significant interethnic differences in treatment responses (P = 0.232 for treatment-race interaction; P < 0.001 for treatment effect). The dropout rates were similar between the two groups (acarbose, 11 of 63; placebo, 6 of 63). There were no significant laboratory adverse events in either group.

CONCLUSIONS

In this multicenter study involving six ethnic groups, acarbose 100 mg t.i.d. was an effective, safe, and generally well-tolerated therapy in Asian type 2 diabetic patients with dietary failure. In some patients with troublesome gastrointestinal symptoms, a lower dosage may be necessary.

Gemfibrozil treatment of endogenous hypertriglyceridemia: effect on insulin-mediated glucose disposal and plasma insulin concentrations

Gemfibrozil or placebo was administered for 3 months to 24 individuals with endogenous hypertriglyceridemia and normal glucose tolerance. Mean ( +/- SEM) fasting plasma triglyceride (TG) concentrations decreased (4.01 +/- 0.55 to 1.34 +/- 0.12 mmol/L; P < 0.001) and high density lipoprotein cholesterol concentrations increased (0.54 +/- 0.03 to 0.67 +/- 0.04 mmol/L; P < 0.001) in gemfibrozil-treated patients, associated with lower (P < 0.01-0.001) plasma free fatty acid and TG concentrations when measured at hourly intervals in response to breakfast (0800 h) and lunch (1200 h). However, day-long plasma glucose and insulin responses to meals in the 2 groups were similar before and after treatment, as were the steady state plasma glucose and insulin concentrations at the end of a 180-min infusion of somatostatin, insulin, and glucose. Thus, marked decreases in both plasma TG and free fatty acid concentrations seen in association with gemfibrozil neither enhanced insulin-mediated glucose disposal nor lowered ambient plasma insulin concentrations in patients with endogenous hypertriglyceridemia.

Quantitative trait locus mapping of human blood pressure to a genetic region at or near the lipoprotein lipase gene locus on chromosome 8p22

Resistance to insulin-mediated glucose disposal is a common finding in patients with non-insulin-dependent diabetes mellitus (NIDDM), as well as in nondiabetic individuals with hypertension. In an effort to identify the generic loci responsible for variations in blood pressure in individuals at increased risk of insulin resistance, we studied the distribution of blood pressure in 48 Taiwanese families with NIDDM and conducted quantitative sib-pair linkage analysis with candidate loci for insulin resistance, lipid metabolism, and blood pressure control. We found no evidence for linkage of the angiotensin converting enzyme locus on chromosome 17, nor the angiotensinogen and renin loci on chromosome 1, with either systolic or diastolic blood pressures. In contrast, we obtained significant evidence for linkage or systolic blood pressure, but not diastolic blood pressure, to a genetic region at or near the lipoprotein lipase (LPL) locus on the short arm of chromosome 8 (P = 0.002, n = 125 sib-pairs, for the haplotype generated from two simple sequence repeat markers within the LPL gene). Further strengthening this linkage observation, two flanking marker loci for LPL locus, D8S261 (9 cM telomeric to LPL locus) and D8S282 (3 cM centromeric to LPL locus), also showed evidence for linkage with systolic blood pressure (P = 0.02 and 0.0002 for D8S261 and D8S282, respectively). Two additional centromeric markers (D8S133, 5 cM from LPL locus, and NEFL, 11 cM from LPL locus) yielded significant P values of 0.01 and 0.001, respectively. Allelic variation around the LPL gene locus accounted for as much as 52-73% of the total interindividual variation in systolic blood pressure levels in this data set. Thus, we have identified a genetic locus at or near the LPL gene locus which contributes to the variation of systolic blood pressure levels in nondiabetic family members at high risk for insulin resistance and NIDDM.

Increased urinary excretion of sulfated 3,3',5-triiodothyronine in patients with nodular goiters receiving suppressive thyroxine therapy

Increased serum 3,3',5-triiodothyronine sulfate (T3S) levels have been detected in various pathophysiologic states. However, little is known about T3S concentrations in other biological fluids. By employing a highly sensitive, specific, and reproducible radioimmunoassay (RIA), we measured T3S in the serum and urine of 20 premenopausal women with benign nodular goiters before and after administration of thyroxine for 6 months (T4; 3.2 micrograms/kg/day). Serum T3 concentrations did not change significantly after treatment (2.0 vs. 1.7 nmol/L; p > 0.05). However, the mean serum T4 and free T4 concentrations were significantly higher after treatment (138 vs. 88 nmol/L and 28 vs. 17 pmol/L; p < 0.01, respectively). Serum thyroid stimulating hormone (TSH) levels were significantly reduced after T4 treatment (0.13 vs. 0.66 mU/L, p < 0.01) and the serum levels of T3S were significantly increased after treatment (82 vs. 45 pmol/L; p < 0.01). A good correlation was observed between increased serum T3S and T4 concentrations (r = 0.66; p < 0.001). The sulfoconjugate of T3 was significantly increased in creatinine-corrected urine after treatment (606 vs. 253 pmol/umol Cr.; p < 0.01). There was a significant correlation between increased creatinine-corrected urine T3S and increased serum free T4 (r = 0.65; p < 0.001). In summary, significant increases in serum and urine T3S levels were noted in T4-treated patients with subnormal serum TSH and borderline elevated T4. We thus conclude that the sulfation pathway may play a role in the homeostasis of thyroid hormone metabolism in T4-treated subjects with relative hyperthyroxinemia. In addition, the creatinine-corrected urine concentrations of T3S may serve as an index for the evaluation of T4-treated patients with elevated levels of T4.

Suppression of non-esterified fatty acid concentrations by insulin in patients with hypertension

BACKGROUND

Recent studies have suggested that insulin resistance may be involved in the development of hypertension. Although skeletal muscle accounts for the majority of peripheral insulin resistance, the effect of insulin on adipose tissue, (i.e., antilipolysis) has rarely been defined in hypertensive patients. To understand the effect of high blood pressure on adipose tissue lipolytic activity in vivo, plasma non-esterified fatty acid (NEFA) concentrations at basal insulin, and during physiological hyperinsulinemic state was compared in patients with essential hypertension and a group of normotensive subjects.

METHODS

Twenty patients with untreated essential hypertension and 20 age, sex, body mass index (BMI)-matched normotensive subjects were studied. Oral glucose tolerance test (OGTT) in response to a 75-g oral glucose load was carried out for three hours after an overnight fasting. On separate morning, modified insulin suppression test was performed for three hours, which involved a constant infusion of insulin (25 mU/m2/min) glucose (240 mg/m2/min) and somatostatin (350 micrograms/h). The four values obtained every 10 min at last half hour were read as steady state plasma glucose (SSPG), insulin (SSPI) and final NEFA concentrations.

RESULTS

Patients with hypertension had significantly higher fasting plasma insulin (101 +/- 9 vs 69 +/- 8 pmol/L, p < 0.02) and NEFA (543 +/- 38 vs 453 +/- 25 mumol/L, p < 0.05) concentrations compared to normotensive subjects. In response to OGTT, the plasma glucose and insulin concentrations increased significantly in the hypertensive group when compared with normotensive group (p < 0.05 and p < 0.01, respectively), whereas plasma NEFA concentrations were suppressed to a similar extent in these two groups. During modified insulin suppression test, the mean SSPG concentrations were significantly higher (10.1 +/- 0.7 vs 7.8 +/- 0.8 mmol/L, p < 0.01) in patients with hypertension compared with normal subjects despite that the mean SSPI concentrations were similar. Plasma NEFA concentrations fell markedly during the period of physiological hyperinsulinemia and achieved similar levels during the last 30 min of infusion in both hypertensive and normal individuals (92.3 +/- 4.9 vs 86.5 +/- 7.3 mumol/L, p = NS).

CONCLUSIONS

Patients with hypertension are glucose intolerant, hyperinsulinemic and insulin resistant compared to a group of normotensive subjects. Hypertensive patients have higher than normal fasting plasma NEFA and insulin concentrations indicating that they might lose the ability to regulate adipocyte metabolism in fasting state.

Effect of glipizide treatment on response to an infused glucose load in patients with NIDDM

OBJECTIVE

This study was initiated to compare the effect of sulfonylurea treatment on the response to an infused glucose load of patients with non-insulin-dependent diabetes mellitus (NIDDM) at a basal insulin concentration and in response to physiological hyperinsulinemia.

RESEARCH DESIGN AND METHODS

We used the insulin suppression test, in which subjects were infused for 180 min with somatostatin, exogenous insulin, and glucose. Since similar steady-state plasma insulin (SSPI) concentrations are reached in all subjects, the resultant steady-state plasma glucose (SSPG) concentration permits comparison of the ability of a given individual to maintain glucose homeostasis in response to the infused glucose load.

RESULTS

We studied 15 nonobese patients at two different SSPI concentrations, before and after glipizide treatment, at basal (68 +/- 4 pmol/l) and high (470 +/- 31 pmol/l) levels. Values for SSPG concentrations were lower after treatment at both the basal (15.3 +/- 0.5 vs. 18.5 +/- 0.6 mmol/l; P < 0.001) and the high (10.6 +/- 0.7 vs. 14.2 +/- 0.7 mmol/l; P < 0.001) SSPI concentrations. To compare the responses of each patient before and after treatment, we calculated the fractional glucose metabolic rate, i.e., (glucose infusion rate--urinary glucose loss) divided by SSPG. To provide an alternative method of comparing the effect of sulfonylurea treatment, we divided the incremental increase in fractional metabolic glucose rate between the studies done at the low and high SSPI by the incremental increase in SSPI between the two studies (insulin sensitivity index [SI]).

CONCLUSIONS

The results of these calculations indicated that glipizide treatment was associated with a significant increase in fractional glucose metabolic rate at a basal insulin concentration (29 +/- 3 to 42 +/- 2 ml.m-2.min-1, P < 0.001), and in response to the incremental change in SSPI (14 +/- 4 to 23 +/- 3 ml.m-2.min-1, P < 0.02). Finally, SI also increased in association with sulfonylurea (0.24 +/- 0.06 to 0.43 +/- 0.07 ml.m-2.min-1/microU.ml-1, P < 0.001).

Metabolic abnormalities following heart transplantation in patients with idiopathic cardiomyopathy

The purpose of this study was to evaluate the risk factors for coronary artery disease associated with initiation of immunosuppressive therapy in patients with a pre-heart transplant diagnosis of idiopathic cardiomyopathy. This study was performed in 15 consecutive patients, mean +/- SEM age of 39 +/- 2 years, with a pre-operative diagnosis of idiopathic cardiomyopathy, who underwent cardiac transplantation at the Tri-Services General Hospital, Taipei, Taiwan, from July 1992 to June 1993. All patients were treated with cyclosporine, azathioprine and prednisolone, and the following measurements were performed prior to hospital discharge (mean +/- SEM) 36 +/- 3 days after successful transplantation: 1) fasting plasma lipid and lipoprotein concentrations; 2) plasma glucose and insulin concentrations in response to a 75 g oral glucose challenge; and 3) steady-state plasma insulin (SSPI) and glucose (SSPG) concentrations in response to a continuous infusion of somatostatin, insulin, and glucose. Since the SSPI concentrations are similar in all individuals, the SSPG concentrations provide an estimate of the ability of insulin to stimulate glucose disposal. Only six of the patients had a normal oral glucose tolerance test and the following diagnoses were found in the remaining nine patients: not diagnised (n = 3), impaired glucose tolerance (n = 4), and non-insulin-dependent diabetes (n = 2). Plasma lipid and lipoprotein concentrations were also frequently abnormal in the heart transplant patients; eight of the 15 patients had a plasma cholesterol > 5 mmol/l, nine had a high density lipoprotein (HDL)-cholesterol concentration < 1 mmol/l, and nine had a ratio of total to HDL-cholesterol > 5.0. Finally, the SSPG concentration was greater than 11.0 mmol/l in eight of the 15 patients, a value rarely exceeded in healthy volunteers. In conclusion, significant metabolic abnormalities were present at discharge in patients who had undergone successful cardiac transplantation for idiopathic cardiomyopathy. These metabolic abnormalities were probably caused by the use of immunosuppressive drugs. Given the magnitude of these changes, it would seem prudent to initiate therapeutic programs in patients with cardiac transplants that are not simply aimed at preventing rejection, but also address the metabolic abnormalities associated with the immunosuppressive agents used to prolong allograft survival.

Resistance to insulin-mediated glucose uptake and hyperinsulinemia in women who had preeclampsia during pregnancy

Plasma glucose and insulin responses to a 75-g oral glucose load, and the steady-state plasma insulin (SSPI) and glucose (SSPG) concentrations after an infusion of somatostatin, insulin, and glucose, were determined 2 months after delivery in 26 women; 13 who had a normal pregnancy and 13 who developed preeclampsia. The plasma glucose response to oral glucose was not different in the two groups, but the plasma insulin response was significantly greater (P < .02) in those who had been preeclamptic. Although the mean (+/- SE) SSPI concentrations during the infusion study were similar in the two groups (51 +/- 2 v 56 +/- 2 microU/mL), the SSPG concentrations were significantly higher (P < .02) in those who developed preeclampsia (160 +/- 17 v 119 +/- 17 mg/dL). Thus, when studied 2 months after delivery, women who developed preeclampsia were relatively insulin resistant and hyperinsulinemic when compared to those who had an uncomplicated pregnancy.

Relationship between hepatic glucose production and fasting plasma glucose concentration in patients with NIDDM

This study was initiated to reevaluate the changes in basal hepatic glucose production (HGP) rate that occur in patients with non-insulin-dependent diabetes mellitus (NIDDM). Measurements were made in 51 volunteers: 18 with normal glucose tolerance and 33 with newly diagnosed NIDDM of varying degrees of severity. To avoid the methodological problems associated with quantifying HGP over short time periods, using non-steady-state isotopic kinetics, radiolabeled glucose was infused for a 12-h period, from 10 P.M. to 10 A.M. with HGP quantified from 9 to 10 A.M.. The results showed that fasting plasma glucose (FPG) concentration and HGP were significantly correlated (r = 0.68, P < 0.001) in patients with NIDDM. However, when the 33 patients with NIDDM were divided into three groups of 11 each on the basis of FPG concentration, it became clear that the relationship between FPG and HGP was complex. Thus, values for HGP in patients with NIDDM and FPG < 180 mg/dl were not higher than in the normal population (1.67 +/- 0.07 vs. 1.69 +/- 0.04 mg.kg-1.min-1, NS). Significant increases (P < 0.01) in HGP above normal were seen in the 11 patients with NIDDM and FPG concentrations between 180 and 250 mg/dl (2.05 +/- 0.07 mg.kg-1.min-1), as well as in those with FPG > 250 mg/dl (2.18 +/- 0.13 mg.kg-1.min-1). Although those with the highest FPG concentrations tended to have the greatest values for HGP, the difference between the latter two groups of patients with NIDDM was not statistically significant. Finally, HGP rates in the 11 patients with FPG concentrations > 250 mg/dl were only 29% higher than values in the control population.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic insulin extraction and insulin clearance in patients with essential hypertension

To understand the mechanism of hyperinsulinemia in patients with high blood pressure, we studied 20 untreated essential hypertensives and 20 age, sex and body mass index-matched normotensive control subjects. C-peptide concentrations and C-peptide to insulin molar ratio in response to a 75 g oral glucose challenge were used to evaluate the beta cells function and for calculation of hepatic extraction of insulin. Modified insulin suppression test was employed to compared the insulin-stimulated glucose uptake and insulin clearance rate between two groups. Patients with hypertension had significantly higher plasma glucose, insulin and C-peptide responses as compared to normal subjects (P < 0.05, p < 0.01, and P < 0.03, respectively). Mean steady state plasma glucose (SSPG) concentrations were also higher in hypertensive group than normotensive group (11.5 +/- 1.4 vs 6.7 +/- 0.9 mmol/L, p < 0.01) despite that mean steady state plasma insulin (SSPI) values were relatively similar, indicating the presence of insulin resistance. Hepatic insulin extraction was found to be elevated in patients with high blood pressure when compared to normal subjects (82 +/- 3 vs 72 +/- 2%, p < 0.05). However, there were no difference in insulin clearance rate between two groups (592 +/- 38 vs 559 +/- 40 mL/m2/min, p = NS). In conclusion, hyperinsulinemia in patients with hypertension result from hypersecretion of beta cells and increased hepatic extraction of insulin. No difference was found in insulin clearance rate between hypertensive and normotensive subjects.

Prospective evaluation of insulin resistance and lipid metabolism in women receiving oral contraceptives

OBJECTIVES

It has been suggested that normal women receiving oral contraceptives (OC) may develop a series of metabolic side-effects which relate to the risk of cardiovascular disease. These metabolic disturbances include changes in glucose and insulin metabolism, raised serum lipid and lipoprotein concentrations and elevated blood pressure. All these changes indicate that OC might cause insulin resistance. We have prospectively examined the effect of OC on insulin resistance and lipid metabolism including Lp(a) values.

PATIENTS

The study group comprised 13 normally menstruating Chinese women.

DESIGN

The study subjects were given a combined triphasic oral contraceptive which was administered on a 21-day on, 7-day off medication cyclic regimen, the first pill being administered on day 5 from the beginning of menses. The metabolic investigations were carried out during luteal phase before OC and again the third week of the third month of OC administration.

MEASUREMENTS

Metabolic evaluation including insulin secretion and insulin-mediated glucose uptake were evaluated by oral glucose tolerance test and the modification of insulin suppression test. Fasting triglyceride, cholesterol, HDL-cholesterol and Lp(a) concentrations were also measured.

RESULTS

The plasma glucose and insulin responses during a 75-g oral glucose challenge increased significantly (P < 0.05 and P < 0.03, respectively). The steady-state plasma glucose (SSPG) concentrations achieved during constant infusion of glucose, insulin and somatostatin increased significantly after 3 cycles of OC administration (glucose 7.5 +/- 0.8 vs 12.4 +/- 0.7 mmol/l, P < 0.001) while the steady-state plasma insulin (SSPI) concentrations were relatively similar (410 +/- 14 vs 391 +/- 7 pmol/l, NS). Plasma triglyceride levels increased significantly (0.81 +/- 0.12 vs 1.09 +/- 0.19 mmol/l, P < 0.03) following OC administration. Fasting plasma cholesterol, HDL cholesterol and calculated LDL cholesterol concentrations did not change as compared with baseline values, nor did the ratio of total cholesterol to HDL cholesterol. The Lp(a) concentrations did not change during the administration of OC (81 +/- 25 vs 71 +/- 21 mg/l, NS).

CONCLUSIONS

These data indicated that intake of OC for 3 cycles induced glucose intolerance, hyperinsulinaemia and insulin resistance in normal menstruating Chinese women. These changes occurred in association with elevated plasma triglyceride concentrations and no alteration in Lp(a) or other lipid values.

Effect of pravastatin treatment on glucose, insulin, and lipoprotein metabolism in patients with hypercholesterolemia

Treatment of patients with type IIA hyperlipoproteinemia (HLP) with pravastatin for 3 months led to significant decreases (p < 0.001) in total cholesterol (7.18 +/- 0.30 to 5.75 +/- 0.30 mmol/L), LDL cholesterol (5.56 +/- 0.33 to 4.02 +/- 0.32 mmol/L), and ratio of total cholesterol to HDL cholesterol (6.5 +/- 0.4 to 4.6 +/- 0.4). Decreases of a similar magnitude were also seen in patients with type IIB HLP. Plasma glucose and insulin concentrations after an oral glucose load and from 8 AM to 4PM in response to meals were higher in patients with Type IIB HLP, who also had higher steady-state plasma glucose concentrations after an infusion of somatostatin, insulin, and glucose (12.4 +/- 1 vs 5.5 +/- 0.8 mmol/L, p < 0.001). Because steady-state plasma insulin concentrations were similar in both groups, patients with type IIB HLP were relatively insulin resistant. Furthermore, day-long plasma glucose concentrations and insulin resistance were modestly, but significantly (p < 0.01), greater after treatment in both groups. In conclusion, LDL cholesterol metabolism improved in hypercholesterolemic subjects treated with pravastatin, but the hypertriglyceridemia, insulin resistance, relative glucose intolerance, and hyperinsulinemia present in patients with type IIB HLP either did not improve with treatment or was somewhat worse.

Insulin resistance, glucose intolerance, and hyperinsulinemia in patients with microvascular angina

Plasma glucose and insulin responses to oral glucose and insulin-mediated glucose disposal were determined in 20 patients with microvascular angina and 20 normal volunteers who were similar in terms of age, gender distribution, and degree of obesity. Plasma glucose and insulin responses to a 75-g oral glucose challenge were significantly higher in those with microvascular angina (P < .001), as were steady-state plasma glucose concentrations after a 180-minute infusion of somatostatin, glucose, and insulin (12.2 +/- 1.0 v 7.6 +/- 0.6 mmol/L, P < .001). Since steady-state plasma insulin concentrations were similar in the two groups (627 +/- 32 v 631 +/- 29 pmol/L), these data indicate that patients with microvascular angina are insulin-resistant, glucose-intolerant, and hyperinsulinemic compared with a matched group of normal volunteers.

Effect of nicardipine treatment on carbohydrate and lipoprotein metabolism in patients with hypertension

This study evaluated the effect of nicardipine, calcium channel blocker, monotherapy on blood pressure and metabolic changes. Various aspect of carbohydrate and lipoprotein metabolism were studied before and after 12 weeks of nicardipine treatment in 23 patients with mild to moderate essential hypertension. Nicardipine was well tolerated and induced a significant decrease (p < 0.001) in both systolic and diastolic blood pressure without any changes in heart rate. Plasma levels of fasting glucose, insulin, C-peptide and hemoglobin A1c, hepatic extraction of insulin were similar following nicardipine treatment. Plasma glucose and insulin responses to an oral glucose challenge did not change in association with nicardipine therapy. Although high density lipoprotein (HDL) cholesterol concentration increased slightly, it did not reach statistical significance. Total cholesterol and low density lipoprotein (LDL) cholesterol levels also increased insignificantly. LDL triglyceride and very low density lipoprotein (VLDL) triglyceride concentrations were higher marginally, which resulted in slightly but insignificantly increase in total triglyceride concentration in association with nicardipine monotherapy for 12 weeks. In conclusion, treatment of patients with mild to moderate hypertension with nicardipine led to lower blood pressure effectively while had no significant influence on carbohydrate and lipoprotein metabolism.

Insulin resistance, glucose intolerance, and hyperinsulinemia. Hypertriglyceridemia versus hypercholesterolemia

Plasma glucose and insulin responses to oral glucose and mixed meals and the ability of insulin to stimulate glucose disposal were quantified in normal volunteer subjects and patients with types IIA, IIB, and IV hyperlipoproteinemia (HLP). The results indicated that patients with either type IIB or IV HLP had higher plasma glucose (p < 0.05-< 0.001) and insulin (p < 0.001) responses to both oral glucose and mixed meals compared with the normal subjects and patients with type IIA HLP. Steady-state plasma glucose concentrations (mmol/L) were also higher (p < 0.001) in patients with types IIB (13.3 +/- 0.6) and IV (12.8 +/- 1.2) HLP during a continuous infusion of somatostatin, glucose, and insulin than either the control group (volunteer subjects) (6.2 +/- 0.9) or patients with type IIA HLP (5.6 +/- 1.0). Because the steady-state plasma insulin concentrations were similar in all four groups, patients with either type IIB or IV HLP were resistant to insulin-mediated glucose uptake. These data indicate that patients with hypertriglyceridemia are insulin resistant, glucose intolerant, and hyperinsulinemic, irrespective of the plasma cholesterol concentration. The results further demonstrate that hypercholesterolemic patients with normal triglyceride concentrations do not have any abnormalities of glucose and insulin metabolism.

Glucose, insulin, and lipid metabolism in doxazosin-treated patients with hypertension

The metabolic changes associated with doxazosin treatment of hypertension were evaluated in ten patients with mild hypertension (mean +/- SEM = 150 +/- 3/100 +/- 1 mm Hg) and a plasma triglyceride (TG) concentration > 1.50 mmol/L. The blood pressure was lower after 4 to 6 months of doxazosin treatment (mean +/- SEM = 134 +/- 4/87 +/- 1 mm Hg), which was also associated with a significantly lower plasma insulin response to a 75 g oral glucose load, and lower plasma TG and cholesterol concentrations. In addition, insulin-mediated glucose uptake was significantly greater after doxazosin treatment. These data suggest that doxazosin treatment of patients with mild hypertension is associated with changes in insulin and lipid metabolism that should decrease the risk of coronary heart disease.

Reproducibility of the measurement of insulin sensitivity by the modified insulin suppression test

A significant increase in insulin resistance has been implicated in many human diseases and the absence of a simple, accurate, reproducible measurement of in vivo insulin sensitivity has become a major concern. In order to evaluate the reproducibility of insulin sensitivity measured by the modified insulin suppression test, 12 healthy young Chinese men were subjected to the same test two weeks apart. After three days on a standard diet and an overnight fast, somatostatin (350 micrograms/h), insulin (25 mU/m2/min) and glucose (240 mg/m2/min) were infused concomitantly for three hours. A steady state plasma glucose (SSPG) concentration achieved during the last 30 minutes of infusion represented the measurement of insulin sensitivity. Comparisons between the metabolic clearance rate of insulin (MCRi), plasma total triglyceride and lipoprotein cholesterol fractions on two different days were carried out. The results indicated that mean SSPG concentrations on Day 1 (5.73 +/- 0.43 mmol/L) correlated with mean SSPG concentrations on Day 14 (5.51 +/- 0.38 mmol/L; r = 0.82, p < 0.002). The relationship slope did not differ from 1 (0.74, p > 0.05), the intercept was close to the origin (1.24 mmol/L, p > 0.05) and the mean coefficient of intra-individual variation was 10.3%. There was no difference between the MCRi for Day 1 and Day 14 (529 +/- 26 vs 526 +/- 24 mL/m2/min, p = NS), with a mean coefficient of intra-individual variation of 6.9%.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement in metabolic risk factors for coronary heart disease associated with cilazapril treatment

Patients with hypertension tend to be glucose intolerant, hyperinsulinemic, and dyslipedemic. Since all of these changes increase risk of coronary heart disease (CHD), it is important to know what effect antihypertensive treatment has on these variables. The current open-labelled, uncontrolled study was initiated in order to extend our understanding of these issues. This study was performed in 19 patients with hypertension who were started on an angiotensin converting enzyme (ACE)-inhibitor, cilazapril, with hydrochlorothiazide (HC) added if needed to control blood pressure. Plasma glucose and insulin responses to oral glucose and lipid concentrations were measured before, 26, and 52 weeks after starting treatment. Patients treated with either cilazapril (n = 9) or cilazapril+HC (n = 10) did not differ in terms of original (mean +/- SEM) blood pressure (159 +/- 5/101 +/- 1 v 156 +/- 4/103 +/- 2 mm Hg), age (53 +/- 2 v 54 +/- 2 years), sex distribution (5M:4F v 7M:3F), or body mass index (24.4 +/- 0.5 v 24.2 +/- 0.9 kg/m2). Blood pressure was also similar after 26 (137 +/- 4/88 +/- 1 v 133 +/- 3/90 +/- 1 mm Hg) and 52 (137 +/- 4/87 +/- 1 v 134 +/- 4/89 +/- 2 mm Hg) weeks of treatment. Plasma glucose and insulin responses decreased by 8 +/- 3% (P less than .05) and 25 +/- 9% (P less than .002), respectively, in cilazapril-treated patients, but did not change in those treated with cilazapril plus HC.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin resistance and abnormal electrocardiograms in patients with high blood pressure

Plasma glucose and insulin responses to an oral glucose challenge and fasting plasma lipid and lipoprotein concentration were compared in 25 normal individuals and 53 patients with high blood pressure. Patients with hypertension were further subdivided into two groups--normal electrocardiogram (EKG) (n = 24) or abnormal EKG (n = 29)--using the Minnesota code criteria. Patients with hypertension and an abnormal EKG had significantly higher plasma glucose and insulin concentrations following oral glucose than did the control population. Furthermore, plasma triglyceride (TG) concentration was higher and high density lipoprotein cholesterol concentration lower then normal in hypertensive patients with an abnormal EKG, and the ratio of total to HDL cholesterol was higher in this subgroup. Values for patients with high blood pressure and a normal EKG were intermediate. Insulin-mediated glucose uptake was also measured in a subset of patients with hypertension and either a normal (n = 18) or abnormal (n = 17) EKG. When these two subgroups were compared, those with high blood pressure and an abnormal EKG were significantly more insulin resistant than patients with hypertension and a normal EKG. In addition, they also had higher plasma glucose and insulin responses to oral glucose, higher fasting plasma triglyceride and cholesterol concentrations, and an increase in the ratio of total to HDL cholesterol. Thus, patients with high blood pressure have abnormalities of glucose, insulin, and lipid metabolism when compared to a nonhypertensive control group, and the magnitude of these metabolic defects is significantly greater in patients with high blood pressure who have EKG evidence of coronary heart disease.

Effect of gemfibrozil treatment in sulfonylurea-treated patients with noninsulin-dependent diabetes mellitus

This study was initiated to 1) assess gemfibrozil's ability to lower plasma triglyceride (TG) concentration in patients with NIDDM, and 2) determine whether this effect was associated with any changes in glycemic control. Measurements were made of mean hourly plasma glucose, insulin, TG, and FFA concentrations from 1200-1600 h in response to a test meal; hepatic glucose production (HGP); insulin-stimulated glucose uptake during a hyperinsulinemic glucose clamp study (MCR); and fasting plasma lipoprotein TG and cholesterol concentrations in 12 patients with NIDDM before and 3 months after gemfibrozil treatment. Although ambient plasma TG and FFA concentrations fell significantly, plasma glucose, insulin, HGP, concentrations fell significantly, plasma glucose, insulin, HGP, and glucose MCR did not change. However, when patients were divided into two groups, those with fasting plasma glucose levels above 9 mmol/L (fair control) and those with levels below 9 mmol/L (good control), a different phenomenon was observed. Patients in fair control had significant decreases in mean hourly plasma concentrations of glucose (15.1 +/- 1.7 to 12.6 +/- 0.9 mmol/L; P less than 0.001), insulin (523 +/- 59 to 471 +/- 75 pmol/L; P less than 0.001), FFA (652 +/- 150 to 504 +/- 76 mumol/L), and HGP (9.5 0.4 to 8.1 +/- 0.4 mumol/kg.min; P less than 0.005), and an increase in glucose MCR (2.63 +/- 0.49 to 3.72 +/- 0.54 mL/kg.min; P less than 0.07) in association with a fall in TG from 6.9 +/- 1.3 to 3.5 +/- 0.9 mmol/L (P less than 0.001). Although fasting low density lipoprotein cholesterol increased (1.8 +/- 0.2 to 2.7 +/- 0.2 mmol/L; P less than 0.05), the ratio of total to high density lipoprotein cholesterol decreased (6.84 +/- 0.88 to 5.80 +/- 1.05; P less than 0.02). Despite a significant fall in mean hourly TG concentration (4.6 +/- 0.7 to 3.8 +/- 0.7 mmol/L; P less than 0.001), neither insulin, FFA, HGP, nor glucose MCR changed in patients in good control. Furthermore, the mean hourly plasma glucose concentration increased from 9.2 +/- 0.7 to 11.7 +/- 1.4 mmol/L (P less than 0.001). Low density lipoprotein cholesterol also increased in this group (1.9 +/- 0.2 to 2.7 +/- 0.2 mmol/L; P less than 0.02), but, as before, the ratio of total to high density lipoprotein cholesterol decreased (8.15 +/- 1.93 to 6.36 +/- 1.03; P less than 0.02).

Coronary artery disease in Chinese males without hypercholesterolaemia

The aim of this study was to determine the frequency of various metabolic risk factors for coronary artery disease (CAD) in 246 male patients studied over a 2-year period. CAD was diagnosed on the basis of a history indicative of angina pectoris, an electrocardiogram diagnostic of myocardial ischaemia, and a positive coronary angiogram. Thirty-eight per cent of this population had diabetes, hypertension or both. Of the remaining individuals, 39% had a plasma cholesterol concentration greater than 5.2 mmol l-1, whereas 23% had a cholesterol concentration less than 5.2 mmol l-1. Plasma lipid and lipoprotein levels of a non-smoking subset of those subjects with a total cholesterol concentration less than 5.2 mmol l-1 were compared with values of a matched group of individuals who did not have significant vessel disease as revealed by angiography. The results of these investigations indicated that patients with CAD and a plasma cholesterol concentration less than 5.2 mmol l-1 exhibited an increase in plasma triglyceride concentration and a decrease in plasma HDL-cholesterol concentration. Since these subjects were not diabetic, hypertensive or hypercholesterolaemic, it is suggested that the observed changes in triglyceride and HDL metabolism made a major contribution to the CAD in these individuals.

Effect of low fat-high carbohydrate diets in hypertensive patients with non-insulin-dependent diabetes mellitus

Effects of variations in dietary fat and carbohydrate content on various aspects of glucose, insulin, and lipoprotein metabolism were evaluated in 11 patients with hypertension, who also had non-insulin-dependent diabetes mellitus (NIDDM). All of these patients were being treated with sulfonylureas, thiazides, and beta-adrenergic receptor antagonists. The comparison diets contained either 40 or 60% of total calories as carbohydrate, with reciprocal changes in fat content from 40 to 20%. The diets were consumed in a random order for 15 days in a crossover experimental design. The ratio of polyunsaturated to saturated fat and total cholesterol intake were held constant in the two diets. Plasma glucose and insulin concentrations were significantly (P less than .001) elevated throughout the day when patients consumed the 60% carbohydrate diet. Fasting plasma total and very-low-density lipoprotein (VLDL) and triglyceride (TG) concentrations increased by 30% (P less than .001) after 15 days on the 60% carbohydrate diet. Total plasma cholesterol concentrations were similar on both diets, as were low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol concentrations.

Effect of chronic renal failure on high-density lipoprotein kinetics

Plasma lipid and lipoprotein concentration and high density lipoprotein (HDL) kinetics were determined in control subjects and patients with chronic renal failure (CRF). Results demonstrated that plasma triglyceride (TG) concentration was significantly higher (P less than 0.001) in patients with CRF, associated with a significant increase in plasma VLDL-cholesterol (P less than 0.002) and a significant decrease (P less than 0.05) in plasma HDL-cholesterol concentration. The rate of removal of 125I-apoAI/HDL from plasma was slower (P less than 0.001) in the patients with CRF, resulting in an increase in the residence time of 125I-apoAI/HDL (P less than 0.001) and a decrease in the fractional catabolic rate (P less than 0.001). Since plasma apoAI concentration was lower in patients with CRF, total apoAI/HDL synthetic rate was also significantly (P less than 0.05) decreased. These data provide support for the view that low plasma HDL-cholesterol concentrations in patients with CRF are related to decreases in the synthetic rate of apoAI/HDL.

Metabolic effects of diuretic and beta-blocker treatment of hypertension in patients with non-insulin-dependent diabetes mellitus

Patients with non-insulin-dependent diabetes mellitus (NIDDM) and hypertension were studied before and after three months of combined beta-blocker-diuretic treatment. Blood pressure fell significantly (P less than .001) from (mean +/- SEM) 167 +/- 3/99 +/- 1 to 142 +/- 3/88 +/- 1 mm Hg. However, mean (+/- SEM) fasting plasma glucose concentration increased significantly (P less than .001) from 132 +/- 11 to 153 +/- 10 mg/dL. In addition, significant increases (P less than .05) were noted in fasting concentration of plasma total triglyceride, very-low-density lipoprotein (VLDL)-triglyceride and VLDL-cholesterol, whereas fasting plasma high-density lipoprotein (HDL)-cholesterol was significantly lower (P less than .05). Thus, a common treatment program for hypertension exacerbated the abnormalities of carbohydrate and lipid metabolism commonly present in patients with NIDDM. Since the changes noted would increase risk of vascular disease, attention should be focused on selection of treatment programs for lowering blood pressure in patients with NIDDM in order to avoid this outcome.

Resistance to insulin-stimulated-glucose uptake in patients with hypertension

Plasma glucose and insulin responses to a glucose challenge and insulin-stimulated glucose uptake were measured in 24 age-, weight-, and sex-matched Chinese men (8 with normal blood pressure, 8 with untreated hypertension, and 8 patients with hypertension treated with thiazide and beta-adrenergic antagonist drugs). Plasma glucose and insulin responses were determined by measuring plasma glucose and insulin concentrations before and at 30-min intervals for 2 h after a 75-g oral glucose dose. Insulin-stimulated glucose uptake was estimated by measuring the steady state plasma glucose (SSPG) and insulin (SSPI) concentrations achieved during the last 60 min of a 180-min continuous infusion of somatostatin, insulin, and glucose (insulin suppression test). Under these conditions endogenous insulin secretion was suppressed, and similar SSPI concentrations were achieved in all men; thus, the differences in the resultant SSPG concentrations allowed direct comparison of insulin's ability to stimulate disposal of an identical glucose load in different individuals. The results indicated that the men with hypertension, whether treated or untreated, had significantly elevated plasma glucose (P less than 0.001) and insulin (P less than 0.001) responses to the oral glucose dose compared to the normal men. Mean (+/- SE) SSPG concentrations were also higher (P less than 0.001) in the men with either untreated hypertension [219 +/- 9 mg/dL (12.2 +/- 0.5 mmol/L)] or treated hypertension [211 +/- 18 mg/dL (11.7 +/- 1.0 mmol/L)] than in the normal men [134 +/- 13 mg/dL (7.4 +/- 0.7 mmol/L)]. Since the mean SSPI concentrations were similar in the 3 groups [approximately 70 microU/mL (502 pmol/L)], insulin was less effective in promoting glucose disposal in both groups with hypertension. These results document the fact that patients with hypertension, whether treated or untreated, are insulin resistant, hyperglycemic, and hyperinsulinemic compared to a well-matched control group.

Plasma lipid and lipoprotein concentrations in Chinese males with coronary artery disease, with and without hypertension

Plasma lipid and lipoprotein concentrations were determined in 125 Chinese males with a medical history and electrocardiographic abnormalities consistent with the diagnosis of coronary artery disease (CAD). All subjects underwent coronary arteriography, and patients were divided into 3 groups based upon the results of the coronary arteriograms: 1) patients with a negative angiogram (CAD-, n = 30), without hypertension; 2) patients with a positive angiogram, without hypertension (CAD+, n = 70); and 3) patients with a positive angiogram, who had hypertension (CAD + HT, n = 25). Mean fasting plasma lipid and lipoprotein concentrations of these 3 groups of patients were compared to values in age and weight-matched groups of normal individuals (n = 80) and untreated patients with hypertension and no evidence of CAD (HT, n = 20). The results indicated that total plasma triglyceride, cholesterol, and LDL-cholesterol levels were significantly higher (P less than 0.001) than normal in patients with CAD+ and CAD + HT, whereas only plasma cholesterol levels were higher than normal in patients with HT. Although patients with CAD- had values intermediate between normal and CAD, the differences were not statistically significant. In addition, the ratio of LDL to HDL-cholesterol was significantly increased (P less than 0.05-0.001) above normal in patients with CAD+, CAD + HT, and HT. As before, the values in patients with CAD- were intermediate. These data document the presence of multiple abnormalities of lipid and lipoprotein concentration in patients with angiographic evidence of CAD, whether or not they were hypertensive. Furthermore, abnormalities in lipid and lipoprotein metabolism were seen in patients with hypertension alone.

Association of low plasma high density lipoprotein (HDL)-cholesterol concentration with documented coronary artery disease in males with non-insulin dependent diabetes mellitus

Plasma lipid and lipoprotein concentrations were determined in 30 males without diabetes or symptomatic coronary artery disease (CAD), and compared to the values in age-matched and weight-matched males (n = 55) with non-insulin-dependent diabetes mellitus (NIDDM). Patients with NIDDM were further subdivided into those with (n = 30) and without (n =25) CAD. Mean (+/- SEM) plasma triglyceride concentrations were significantly increased (P less than 0.001) over control values (96 +/- 5 mg/dl) in patients with NIDDM, whether with (172 +/- 14 mg/dl) or without documented CAD (164 +/- 25 mg/dl). Plasma cholesterol concentrations were also higher (P less than 0.001) than normal (168 +/- 5 mg/dl) in both groups of patients with NIDDM (201 +/- 11 and 199 +/- 7 mg/dl, respectively, in patients with and without evidence of CAD). Plasma LDL-cholesterol concentrations were also greater (P less than 0.001) than normal (104 +/- 4 mg/dl) in patients with NIDDM, but were again similar in the group of diabetics (120 +/- 9 vs 128 +/- 6 mg/dl). However, plasma HDL-cholesterol concentrations were only reduced below control values in diabetes patients with CAD (30 +/- 1 mg/dl), whereas patients with NIDDM and no subjective evidence of CAD had HDL-cholesterol concentrations (37 +/- 3 mg/dl) which were similar to normal values (38 +/- 2 mg/dl). As a result, the ratio of LDL-cholesterol to HDL-cholesterol was highest in patients with NIDDM and CAD (4.2 +/- 0.3), lowest in the control population (2.8 +/- 0.2), and intermediate in those patients with NIDDM without subjective or objective evidence of CAD (3.6 +/- 0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities of carbohydrate and lipid metabolism in patients with hypertension

Plasma glucose, insulin, and lipoprotein concentrations were determined in 20 men with hypertension, and compared with values in 20 normotensive men of comparable age and body mass index. The results demonstrated a significant increase in both the plasma glucose and insulin response to a 75-g oral glucose challenge (two-way analysis of variance). In addition, a significant correlation existed between the plasma blood pressure. Finally, the greater the plasma glucose insulin response to oral glucose and both systolic and diastolic and insulin responses to oral glucose, the lower the plasma high-density lipoprotein concentrations, and the higher the ratio of plasma low-density lipoprotein cholesterol to high-density lipoprotein cholesterol. Thus, abnormalities of plasma glucose, insulin, and lipoprotein metabolism exist in patients with untreated hypertension, and these changes may contribute to the increased risk for coronary artery disease associated with hypertension.