Discovery of Novel Quinoline-Based Proteasome Inhibitors for Human African Trypanosomiasis (HAT)

Human African Trypanosomiasis (HAT) is a vector-borne disease caused by kinetoplastid parasites of the Trypanosoma genus. The disease proceeds in two stages, with a hemolymphatic blood stage and a meningo-encephalic brain stage. In the latter stage, the parasite causes irreversible damage to the brain leading to sleep cycle disruption and is fatal if untreated. An orally bioavailable treatment is highly desirable. In this study, we present a brain-penetrant, parasite-selective 20S proteasome inhibitor that was rapidly optimized from an HTS singleton hit to drug candidate compound 7 that showed cure in a stage II mouse efficacy model. Here, we describe hit expansion and lead optimization campaign guided by cryo-electron microscopy and an in silico model to predict the brain-to-plasma partition coefficient K_p as an important parameter to prioritize compounds for synthesis. The model combined with in vitro and in vivo experiments allowed us to advance compounds with favorable unbound brain-to-plasma ratios (K_p,uu) to cure a CNS disease such as HAT.

Discovery and Characterization of Clinical Candidate LXE408 as a Kinetoplastid-Selective Proteasome Inhibitor for the Treatment of Leishmaniases

Visceral leishmaniasis is responsible for up to 30,000 deaths every year. Current treatments have shortcomings that include toxicity and variable efficacy across endemic regions. Previously, we reported the discovery of GNF6702, a selective inhibitor of the kinetoplastid proteasome, which cleared parasites in murine models of leishmaniasis, Chagas disease, and human African trypanosomiasis. Here, we describe the discovery and characterization of LXE408, a structurally related kinetoplastid-selective proteasome inhibitor currently in Phase 1 human clinical trials. Furthermore, we present high-resolution cryo-EM structures of the Leishmania tarentolae proteasome in complex with LXE408, which provides a compelling explanation for the noncompetitive mode of binding of this novel class of inhibitors of the kinetoplastid proteasome.

Nidufexor (LMB763), a Novel FXR Modulator for the Treatment of Nonalcoholic Steatohepatitis

Farnesoid X receptor (FXR) agonists are emerging as important potential therapeutics for the treatment of nonalcoholic steatohepatitis (NASH) patients, as they exert positive effects on multiple aspects of the disease. FXR agonists reduce lipid accumulation in the liver, hepatocellular inflammation, hepatic injury, and fibrosis. While there are currently no approved therapies for NASH, the bile acid-derived FXR agonist obeticholic acid (OCA; 6-ethyl chenodeoxycholic acid) has shown promise in clinical studies. Previously, we described the discovery of tropifexor (LJN452), the most potent non-bile acid FXR agonist currently in clinical investigation. Here, we report the discovery of a novel chemical series of non-bile acid FXR agonists based on a tricyclic dihydrochromenopyrazole core from which emerged nidufexor (LMB763), a compound with partial FXR agonistic activity in vitro and FXR-dependent gene modulation in vivo. Nidufexor has advanced to Phase 2 human clinical trials in patients with NASH and diabetic nephropathy.

Acute changes in Atherogenic and Thrombogenic Factors with Cessation of Smoking

Tobacco smoking is associated with alterations in several factors considered to be important in the atherosclerotic process. Thirty chronic smokers were studied 2 weeks before and 2 weeks after complete tobacco withdrawal. Significant reductions in fibrinogen, haematocrit, plasma viscosity and whole blood viscosity as well as a significant increase in HDL-cholesterol were observed. As these factors are important in both atherogenesis and thrombogenesis, these observations may give insight into tobacco-induced atherosclerotic disease and may be responsible for the more rapid reduction in the incidence of cardiovascular disease that is believed to occur after stopped smoking.

Imaging of Plasmodium liver stages to drive next-generation antimalarial drug discovery

Most malaria drug development focuses on parasite stages detected in red blood cells, even though, to achieve eradication, next-generation drugs active against both erythrocytic and exo-erythrocytic forms would be preferable. We applied a multifactorial approach to a set of >4000 commercially available compounds with previously demonstrated blood-stage activity (median inhibitory concentration < 1 micromolar) and identified chemical scaffolds with potent activity against both forms. From this screen, we identified an imidazolopiperazine scaffold series that was highly enriched among compounds active against Plasmodium liver stages. The orally bioavailable lead imidazolopiperazine confers complete causal prophylactic protection (15 milligrams/kilogram) in rodent models of malaria and shows potent in vivo blood-stage therapeutic activity. The open-source chemical tools resulting from our effort provide starting points for future drug discovery programs, as well as opportunities for researchers to investigate the biology of exo-erythrocytic forms.

The effects of rosiglitazone on atherosclerotic progression in patients with Type 2 diabetes at high cardiovascular risk

AIMS

Cardiovascular mortality remains high despite intensive treatment of people with Type 2 diabetes mellitus. Meta-analyses on rosiglitazone have raised concerns regarding its cardiovascular safety. We studied the effects of rosiglitazone on ultrasonic indices of carotid arterial disease and inflammatory markers in a group of Type 2 diabetic patients at high cardiovascular risk.

METHODS

A trial of rosiglitazone in Type 2 diabetic patients with high cardiovascular risk and internal carotid artery plaque compared changes in carotid ultrasound intima-media thickness (IMT), plaque thickness, arterial stiffness and compliance, and inflammatory markers at baseline, 26 and 52 weeks.

RESULTS

In the rosiglitazone group (n=28), carotid artery plaque thickness was reduced by 0.08 mm, compared with an increase of 0.19 mm (P=0.075) in the placebo group (n=29). There were no significant differences in changes of IMT, carotid wall compliance and stiffness between the two groups. Glycated haemoglobin reduced by -0.9 vs. 0.1% (-7 vs. 2 mmol/mol), (P<0.001); insulin resistance (HOMA-IR) reduced by -37.6 vs. -1.1% (P=0.016); and B cell function (HOMA-B) increased by 36.8 vs. 0.7% (P=0.009). Non-esterified fatty acids reduced by -23.5 vs. 7.9% (P=0.005); tissue plasminogen activator reduced by -25.0 vs. 0.6% (P=0.001); and plasminogen activator inhibitor activity reduced by -57.4 vs. -34.6% (P=0.052).

CONCLUSIONS

Rosiglitazone reduced carotid artery plaque thickness, though not significantly, and there was no significant change in intima media thickness or other ultrasonic indices of carotid arterial disease. There were significant improvements in glycaemic control, insulin sensitivity and fibrinolytic, but not inflammatory, markers. There was no evidence in this study of any adverse effects on progression of carotid arterial disease.

Coronary calcification, homocysteine, C-reactive protein and the metabolic syndrome in Type 2 diabetes: the Prospective Evaluation of Diabetic Ischaemic Heart Disease by Coronary Tomography (PREDICT) Study

AIMS

The PREDICT Study aims to determine: (i) the association between cardiovascular risk factors and coronary artery calcification score (CACS) obtained by electron beam tomography and (ii) the predictive value of CACS for coronary heart disease (CHD) events in Type 2 diabetes.

METHODS

Having previously reported relationships between CACS and conventional risk factors, we have now studied the novel risk factors, plasma high-sensitivity C-reactive protein (CRP) and homocysteine, insulin resistance, serum apoprotein A1 and B concentrations, the serum triglyceride/high-density lipoprotein cholesterol ratio and metabolic syndrome (International Diabetes Federation definition) in 573 subjects of the PREDICT Type 2 diabetes cohort.

RESULTS

In univariate analyses, the only significant positive novel correlate of CACS was homocysteine (P = 0.0004). CRP was increased in those with detectable calcification, but decreased with increasing calcification score (P = 0.006). In a multivariate model that included all significant univariate correlates, CACS was independently associated with age (P < 0.0001), waist-hip ratio (P < 0.02), male gender (P < 0.05) and duration of diabetes (P < 0.05), but the association with homocysteine was no longer significant. The negative association between CACS and CRP remained in multivariate analysis, and was independent of statin use.

CONCLUSIONS

Age was the major factor influencing CACS in Type 2 diabetes, with weaker contributions from waist hip-ratio and duration of diabetes. Other novel cardiovascular risk factors appear to have little positive effect.

Design and synthesis of 7H-pyrrolo[2,3-d]pyrimidines as focal adhesion kinase inhibitors. Part 2

A series of 2-amino-9-aryl-7H-pyrrolo[2,3-d]pyrimidines were designed and synthesized as focal adhesion kinase (FAK) inhibitors using molecular modeling in conjunction with a co-crystal structure. Chemistry was developed to introduce functionality onto the 9-aryl ring, which resulted in the identification of potent FAK inhibitors. In particular, compound 32 possessed single-digit nanomolar IC(50) and represents one of the most potent FAK inhibitors discovered to date.

Design and synthesis of 7H-pyrrolo[2,3-d]pyrimidines as focal adhesion kinase inhibitors. Part 1

A series of 2-amino-9-aryl-7H-pyrrolo[2,3-d]pyrimidines were designed and synthesized to target focal adhesion kinase (FAK). A number of these pyrrolopyrimides exhibited low micromolar inhibitory activities against focal adhesion kinase, and their preliminary SAR was established via systematic chemical modifications. The 2-amino-9-aryl-7H-pyrrolo[2,3-d]pyrimidines represent a new class of kinase inhibitors.

Random urine calcium/ osmolality in the assessment of calciuria in children with decreased muscle mass

BACKGROUND

Random urine Ca/creatinine (UCa/Cr) is used to estimate 24-hour Ca excretion. However, due to decreased urine creatinine excretion in children with decreased muscle mass (DMM), UCa/Cr overestimates their Ca excretion.

OBJECTIVE

To evaluate whether in children with DMM random urine Ca/osmolality (UCa/Osm) can accurately predict hypercalciuria (24-hour urine Ca > 4.0 mg/kg) and at which "cutoff" value.

METHODS

19 children with DMM and 29 with normal muscle mass (NMM), ages 6 - 17 years, were studied. DMM was diagnosed based on clinical findings and decreased serum creatinine, and confirmed by low urine creatinine excretion. Over 24 hours, subjects collected each void separately. After each sample was analyzed, samples of each participant were combined to form a 24-hour specimen from which an aliquot (AL) was obtained; 24-hour urine Ca was first correlated with the corresponding AL Ca/Cr and Ca/Osm. As an internal control, a similar assessment ofproteinuria was conducted. In the next step, AL data were compared with individual urine samples to identify the time of day when a random sample best correlates with AL.

RESULTS

The correlation coefficient between 24-hour Ca and AL Ca/Cr in all children was 0.61, in NMM 0.96, and in DMM 0.69 (in all p < 0.001). The correlation coefficient between 24-hour urine Ca and AL Ca/Osm in all children was 0.90, in NMM 0.90, and in DMM 0.91 (in all p < 0.001). In children with DMM, the correlation coefficient of 24-hour protein with AL protein/Cr was 0.75, and with protein/Osm 0.98 (both p < 0.001). Receiver operating characteristic curves showed UCa/Cr as a better predictor of 24-hour Ca > 4.0 mg/kg in NMM, whereas UCa/Osm was a better predictor of hypercalciuria in DMM patients. In NMM, UCa/Cr ratio > 0.20 had sensitivity of 88% and specificity of 96% in detecting 24-hour Ca > 4.0 mg/kg, whereas in those with DMM UCa/Osm (x 10) ratio of > 0.25 had sensitivity of 100% and specificity of 93% in detecting hypercalciuria. It was further found that random urine specimens collected between 9:00 a.m. and 2:00 p.m. best represented 24-hour urine data.

CONCLUSION

In children with DMM, UCa/Osm can successfully replace UCa/Cr as a screening tool for hypercalciuria.

Lack of seasonal variations in urinary calcium/creatinine ratio in school-age children

Seasonal variations in urinary calcium excretion have been observed in adults and are thought to be due to seasonal changes in sunlight exposure, which results in fluctuation of blood levels of 25-hydroxyvitamin D. The goal of the present study was to explore the possible effect of season on urinary calcium/creatinine ratio (UCa/Cr) in healthy school children. We studied 65 healthy Caucasian children aged 5.1-14.6 years (mean+/-SD 9.6+/-2.0, median 9.7 years). Random, non-fasting urine samples were collected from each participant between the 1st and 5th days of the month for 16 successive months and analyzed for UCa/Cr. In parallel, meteorological data, which included average monthly temperature and average monthly UV index, were collected for the whole study period. A mathematical model describing the monthly mean values of UCa/Cr as a sine function was used to determine the presence of seasonal variation. The observed maximum mean UCa/Cr, 0.092 mg/mg (0.260 mmol/mmol), occurred in the late summer months (August/September) and minimum mean UCa/Cr, 0.083 mg/mg (0.235 mmol/mmol), occurred in mid-winter (January/February), reflecting an infinitesimal and statistically insignificant change. Moreover, both values were well within the previously established normal range for UCa/Cr of </=0.20 mg/mg (0.566 mmol/mmol). The pattern seen in the last 4 months of the study repeated that seen in the first 4 months. The mean temperature in July of the 1st year was 27.1+/-2.6, January 1.8+/-5.4, and July of the 2nd year 27.0+/-2.2 degrees C. The mean UV index in July of the 1st year (7.61+/-1.01) was not different from that in July of the 2nd year (7.73+/-0.86), and both were statistically much higher than that in January (1.37+/-0.44) ( P<0.001). Evidently, in spite of significant changes in seasonal meteorological indices of sunlight, no significant seasonal variations in UCa/Cr were observed in a cohort of healthy school children. Thus the current UCa/Cr value used to diagnose hypercalciuria does not require a seasonal adjustment.

The association of coronary calcium score and conventional cardiovascular risk factors in Type 2 diabetic subjects asymptomatic for coronary heart disease (The PREDICT Study)

AIM

To determine the association between coronary calcification score (CACS) obtained by electron beam computed tomography (EBCT) and cardiovascular risk factors in Type 2 diabetic subjects entered into a prospective cohort study.

METHODS

Type 2 diabetic subjects attending routine hospital diabetic clinics without known coronary heart disease (CHD) underwent EBCT to measure CACS. Demographic data were obtained and conventional cardiovascular risk factors were measured at baseline.

RESULTS

Four hundred and ninety-five subjects were assessed of whom 67.7% were male. They had a mean (SD) age of 62.9 (7.1) years, with median (inter-quartile range) duration of diabetes of 8 (4-13) years. None had a history of coronary artery disease. Forty-five per cent were receiving lipid-lowering agents (including 36% statins). In a univariate analysis, there were significant associations between increased CACS and age, duration of diabetes, male gender, waist-hip ratio (WHR), systolic blood pressure, and the use of statins. In a multivariate model adjusting for the possible interaction of these and other factors, the significant association between CACS and WHR, systolic blood pressure, male gender and statin use remained.

CONCLUSIONS

The close association between CACS and WHR and the association with systolic blood pressure suggest that coronary calcification may be particularly linked to the metabolic syndrome in Type 2 diabetes.

Rates of cholesterol esterification and esterified cholesterol net mass transfer between high-density lipoproteins and apolipoprotein B-containing lipoproteins in Type 1 diabetes

AIMS

Type 1 diabetes is associated with a high incidence of coronary heart disease (CHD) despite paradoxically normal or high high-density lipoprotein (HDL) cholesterol concentrations. Triglyceride (TG) concentrations have been shown to be important determinants of two aspects of HDL metabolism: cholesterol esterification rate and esterified cholesterol (EC) net mass transfer rate between HDL and the apolipoprotein B-containing lipoproteins. In order to try to explain the paradox, we aimed to assess the relationships between plasma TG and these two processes in Type 1 diabetic compared with non-diabetic subjects.

METHODS

Rates of cholesterol esterification and EC net mass transfer between HDL and the apolipoprotein B-containing lipoproteins were assessed by incubating whole plasma at 37 degrees C; intra-assay coefficients of variation were 6% and 30%, respectively.

RESULTS

Ten Type 1 diabetic and 10 non-diabetic subjects, with similar ages, sex distributions, body mass indices and total cholesterol and TG concentrations, were assessed. Apolipoprotein A1, HDL unesterified cholesterol, and HDL phospholipid concentrations were greater in the Type 1 diabetic subjects. There were no significant differences in the rates of cholesterol esterification or EC net mass transfer between the groups. There were strong associations between plasma TG and the rate of cholesterol esterification and between plasma TG and the rate of EC net mass transfer in Type 1 diabetic subjects (r = 0.83, P = 0.0027 and r = 0.88, P = 0.0009, respectively) and in non-diabetic subjects (r = 0.91, P = 0.0002 and r = 0.79, P = 0.0070, respectively). However, the slopes of the associations with plasma TG were significantly steeper in the Type 1 diabetic subjects (analyses of covariance P = 0.0053 and P = 0.0146, respectively).

CONCLUSIONS

Increases in TG may therefore promote more EC enrichment of atherogenic apolipoprotein B-containing lipoproteins in Type 1 diabetes while also promoting more cholesterol esterification, thereby maintaining HDL cholesterol concentrations. This could contribute to the paradox of high CHD incidence despite normal or high HDL cholesterol concentrations in Type 1 diabetes.

High-density lipoprotein composition and paraoxonase activity in Type I diabetes

Type I diabetes is associated with a high incidence of coronary heart disease (CHD), despite a normal or even increased concentration of high-density lipoprotein (HDL) cholesterol. This paradox may be explained by changes in the antioxidant capacity of HDL, related to paraoxonase (PON1) activity. HDL compositional changes in subjects with Type I diabetes may result in changes in PON1 activity that are associated with a higher incidence of CHD. Single-vertical-spin density-gradient ultracentrifugation was used to isolate seven HDL fractions from serum according to density. PON1 activity was measured in serum and in the HDL fractions using phenyl acetate as substrate. The mean recovery of PON1 activity in the HDL fractions was 87% (S.D. 12%). CHD risk was assessed using B-mode ultrasound to measure carotid artery intima-media thickness (IMT). Groups of 35 subjects with Type I diabetes [duration of diabetes 18 years (12-32 years) [median (interquartile range)]; glycated haemoglobin 7.67% (1.17%)] and 24 non-diabetic control subjects were studied. Carotid IMT was greater in the diabetic subjects [0.60 (0.55-0.70) compared with 0.55 (0.45-0.64) mm; P=0.042] and HDL cholesterol concentration was higher [1.53 (0.36) compared with 1.32 (0.34) mmol/l; P=0.031]. There were qualitative differences in HDL in subjects with Type I diabetes: HDL particles were triacylglycerol-deplete, and there were greater numbers of the larger, more buoyant HDL particles. These properties were not those found to determine PON1 activity. PON1 activity increased as HDL particle density increased and particle size decreased; the increase in PON1 activity was associated with an increase in the ratio of the two HDL surface lipid components, phospholipid and unesterified cholesterol, as particle density increased. PON1 activity was similar in diabetic and non-diabetic subjects [121 (28) and 120 (36) micromol x min(-1) x ml(-1) respectively; P=0.887]. PON1 activity was not associated with carotid IMT in either group. Our results suggest that the PON1 activities of HDL particles relate to the density, size and composition of the particles. However, PON1 activity does not appear to contribute to the greater risk of CHD in subjects with Type I diabetes.

Total antioxidant status and coronary artery calcification in type 1 diabetes

OBJECTIVE

Type 1 diabetes is associated with a high risk of coronary heart disease (CHD), despite the absence of dyslipidemia. Oxidative modification may render LDLs more atherogenic. We aimed to assess antioxidant status in type 1 diabetes and its association with coronary artery calcification (CAC).

RESEARCH DESIGN AND METHODS

Total antioxidant status (TAS) of serum was measured using the Trolox equivalent antioxidant capacity assay in 48 type 1 diabetic and 25 nondiabetic subjects. The presence of CAC was assessed in the diabetic subjects using electron beam computed tomography.

RESULTS

TAS was reduced in type 1 diabetic subjects compared with nondiabetic subjects (Mann-Whitney U test, P < 0.0001). There were associations between TAS and HbA(1c) (r = -0.43; P = 0.0026) and duration of diabetes (r = -0.35; P = 0.0157). Significant CAC was considered present if the Agatston score was >10. The diabetic subjects with significant CAC were older (P < 0.0001); had longer duration of diabetes (P = 0.0002); were more likely to have high blood pressure (P = 0.040); had higher total cholesterol concentration (P = 0.039), serum creatinine concentration (P = 0.003), and urinary albumin-to-creatinine ratio (P = 0.022); and had lower serum TAS (P = 0.018) compared with those without significant calcification. In logistic regression with CAC as the dependent variable, TAS was entered as a predictor, and the effects on its predictive value of adding other explanatory variables in bivariate analyses were assessed. The power of TAS to predict CAC was independent of many of the traditional CHD risk factors. Whereas TAS as a predictor was no longer statistically significant when age or duration of diabetes were entered into the model, the odds ratio for a TAS concentration above the median value predicting significant CAC only increased from 0.19 to 0.26 and 0.32, respectively.

CONCLUSIONS

TAS is reduced in type 1 diabetes and is associated with the presence of CAC.

Smoking is associated with increased hepatic lipase activity, insulin resistance, dyslipidaemia and early atherosclerosis in Type 2 diabetes

We have studied the relationships between hepatic lipase activity, smoking, dyslipidaemia insulin resistance, and early atherosclerosis in 67 Type 2 diabetic subjects, 47 non-smokers and 20 smokers. Insulin resistance was measured using an insulin modified frequently sampled intravenous glucose tolerance test. Early atherosclerosis was assessed using high-resolution ultrasound to measure carotid intima media thickness (IMT) and an arterial ultrasonic score (AUS). Smokers had higher serum cholesterol and triglyceride, lower HDL and HDL2 cholesterol as well as increased hepatic lipase activity. They were also more insulin resistant than non-smokers. Smokers also had higher patient AUS scores. On multiple regression analysis, hepatic lipase activity emerged as the most significant variable affecting patient AUS. We suggest that smoking accentuates the dyslipidaemia of Type 2 diabetic subjects and this is associated with increased hepatic lipase activity. This may be one mechanism whereby smoking further increases the risk of cardiovascular disease in Type 2 diabetes.

Insulin resistance, cardiovascular risk factors and ultrasonically measured early arterial disease in normotensive Type 2 diabetic subjects

BACKGROUND

The objective of the study was to examine the relationship between serum fasting insulin, insulin sensitivity S(i), cardiovascular risk factors, and asymptomatic early atherosclerosis in normotensive Type 2 diabetic subjects.

METHODS

Specific insulin was measured using an enzyme-linked immunosorbent assay (ELISA) and insulin sensitivity was assessed with an insulin-modified frequently sampled intravenous glucose tolerance test (FSIVGTT). Early atherosclerotic change was assessed using carotid intima media thickness (IMT) and an arterial ultrasound score (AUS) measured by high-resolution B-mode ultrasound.

RESULTS

On bivariate analysis, there was a positive correlation between S(i) and high density lipoprotein (HDL) cholesterol (r(s)=0.27, p<0.05), and a negative correlation between S(i) and body mass index (BMI) (r(s)=-0.42, p<0.001), HbA(1c) (r(s)=-0.29, p<0.05) and serum triglyceride (r(s)=-0.30, p<0.05). There was a positive correlation between carotid IMT and age (r(s)=0.41, p<0.0005), and a positive association with male sex (p<0.0001) as well as with smoking (p<0.0001). However, we found no correlation between carotid IMT and fasting specific insulin (r(s)=-0.04) or S(i) (r(s)=-0.08). On multiple regression analyses, only age and serum triglycerides appeared to be significant independent variables with respect to carotid IMT whereas age, male sex and smoking emerged jointly significant with respect to AUS. There were no independent associations between carotid IMT or AUS with other variables including using either fasting specific insulin or S(i) as markers on insulin resistance separately.

CONCLUSION

Carotid IMT and AUS in Type 2 diabetes are closely associated with age, male sex and smoking. The relationships between serum insulin and insulin resistance with ultrasonically measured early arterial disease in Type 2 diabetes remain unclear.

Myocardial injury in major aortic surgery

PURPOSE

The purpose of this study was to examine the effects of major aortic surgery and its associated oxidative stress and injury on the myocardium.

METHODS

Plasma from 27 patients who underwent thoracoabdominal aortic aneurysm (TAAA) repair and 17 patients who underwent infrarenal aortic aneurysm (AAA) repair was collected at incision, aortic crossclamping, and reperfusion and 1, 8, and 24 hours thereafter. Samples were assayed for the myocardial specific protein troponin-T, total antioxidant status, and lipid hydroperoxides.

RESULTS

Ten patients experienced cardiac dysfunction in the first 24 hours after surgery (eight patients in the TAAA group and two patients in the AAA group). Immediately after reperfusion, total antioxidant status levels dropped in all patients with TAAA and with AAA; this was more marked in patients with TAAA, leading to a significant difference between the two groups at this time point and for up to 1 hour thereafter (P <.01). Patients with TAAA showed a sharp rise in lipid hydroperoxide levels immediately after reperfusion, and levels were significantly higher than in patients with AAA (P =.0007). In patients with AAA, no significant change in troponin-T was observed throughout the study period; whereas in patients with TAAA, levels were significantly elevated at 8 and 24 hours after reperfusion (P <.01). Troponin-T levels significantly correlated with total antioxidant status (r = -0.5) and lipid hydroperoxides (r = 0.78) but not with systolic blood pressure.

CONCLUSION

Supracoeliac aortic crossclamping is associated with a significant release of the myocardial injury marker troponin-T. This seems to correlate with the severity of oxidative rather than hemodynamic stresses. Ameliorating oxidative injury during TAAA surgery may therefore have a cardioprotective effect.

Plasma antioxidants: evidence for a protective role against reactive oxygen species following cardiac surgery

Total plasma antioxidant status (TPAS), lipid peroxide concentration (LPX) and cardiac troponin T (cTnT) were measured in 24 patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). Samples were obtained preoperatively and at 1.5 h, 6 h, 24 h and 72 h after CPB. The absolute TPAS values were significantly lower at 1.5 h, 6 h, 24 h and 72 h after CPB than were preoperative values (P < 0.05). The LPX concentration was significantly elevated at 1.5 h after CPB (P < 0.05). Cardiac troponin T concentrations were significantly elevated at all time points postoperatively (P < 0.05). Preoperative TPAS values were significantly correlated with the magnitude of fall in TPAS at 1.5 h (P < 0.05). The greater the fall in TPAS between 0 and 1.5 h, the less LPX was formed between 0 and 1.5 h. The LPX at 1.5 h displayed a significant correlation with cTnT release from myocardial myocytes (P < 0.05). These data provide evidence for the first time that the consumption of antioxidants during CABG surgery with CPB protects against the production of reactive oxygen species and subsequent myocyte necrosis. Furthermore, the availability of protective antioxidants is dependent upon preoperative TPAS.

Effects of four years' treatment with biosynthetic human growth hormone (GH) on glucose homeostasis, insulin secretion and lipid metabolism in GH-deficient adults

OBJECTIVE

To study the effects of long-term growth hormone (GH) treatment on lipid metabolism and carbohydrate tolerance in GH-deficient adults.

DESIGN

Open trial of GH treatment for 4 years. GH dose was (median, range) 0.025 (0.010-0.050) IU/kg daily.

PATIENTS

Thirteen GH-deficient hypopituitary adults (seven men, six women), aged (median, range) 47 (24-65) years were followed for 4 years.

MEASUREMENTS

Fasting lipids, lipoproteins, apolipoproteins, glucose and insulin concentrations were measured at yearly intervals during GH therapy. A 75-g oral glucose tolerance test (OGTT) was also performed yearly, during which circulating glucose and insulin were measured at 30-minute intervals for 3 h.

RESULTS

Fasting total and low density lipoprotein (LDL) cholesterol concentrations decreased on GH therapy, but no change was observed in fasting triglyceride or high density lipoprotein (HDL) concentrations. Compared to pretreatment values, total and LDL cholesterol levels were significantly lower at 1 year (mean +/- SEM) (6.39 +/- 0.46 vs. 5.71 +/- 0.38 mmol/l, P < 0.05; 4.46 +/- 0.36 vs. 3.24 +/- 0.20 mmol/l, P < 0.01, respectively) and the reductions were maintained for the 4 years. Apolipoproteins A-1 and B did not differ significantly from the pretreatment levels. Fasting plasma glucose increased significantly at the first year (4.9 +/- 0.1 vs. 5.3 +/- 0.1 mmol/l, P < 0.05) but it returned to the pretreatment value in the following years. Fasting plasma insulin increased significantly at 1 year (4.3 (1.0-13.6) vs. 11.9 (1.2-26.9) mU/l, P < 0.05) and showed a progressive downward trend but remained significantly raised throughout the subsequent years. The 3-h area under the glucose curve (AUC) during the OGTT tended to be increased at the first year (P = 0.07) and it returned to the pretreatment level in the following years. The AUC of plasma insulin was significantly raised at 1 year (P = 0.024) and it returned to the pretreatment level in the following years.

CONCLUSIONS

Four years of GH therapy in GH-deficient adults resulted in a sustained improvement in total and LDL cholesterol concentrations. Mild fasting hyperinsulinaemia persisted, although an initial deterioration in glucose tolerance, associated with post-glucose hyperinsulinaemia, was not sustained.

Investigation into voltage breakdown in glyceryl trinitrate patches

There are clinical reports of explosions occurring in glyceryl trinitrate (GTN) patches left on patients who are defibrillated and it is widely recommended that such patches are removed before attempting defibrillation. We devised an experimental set up that simulated the electrical conditions under which human defibrillation is conducted, thus making possible accurate measurements of defibrillator wave form. No problems occurred with GTN patches that incorporated a plastic backing. However, with GTN patches that incorporated a metal mesh backing, an explosive effect was consistently observed when current from the defibrillator electrode flowed through the metallic backing. The GTN paste in the patches was unaffected and therefore, we conclude that the apparent explosions reported are solely due to voltage breakdown as the paddle voltage is close to 3 kV resulting from the 360 J of energy. Our results emphasise the need for good technique during defibrillation to avoid current flow through such patches. In addition, our results have implications for the design of patches used for the transcutaneous delivery of drugs.

Cardiovascular outcomes in type 2 diabetes. A double-blind placebo-controlled study of bezafibrate: the St. Mary's, Ealing, Northwick Park Diabetes Cardiovascular Disease Prevention (SENDCAP) Study

OBJECTIVE

To determine whether serum lipid intervention, in addition to conventional diabetes treatment, could alter cardiovascular outcomes in type 2 diabetes.

RESEARCH DESIGN AND METHODS

There were 164 type 2 diabetic subjects (117 men, 47 women) without a history of clinical cardiovascular disease randomized to receive either bezafibrate or placebo daily on a double-blind basis in addition to routine diabetes treatment and followed prospectively for a minimum of 3 years. Serial biochemical and noninvasive vascular assessments, carotid and femoral artery B-mode ultrasound measurements, and those pertaining to coronary heart disease (CHD)--clinical history, the World Health Organization (WHO) cardiovascular questionnaire, and resting and exercise electrocardiogram (ECG)--were recorded.

RESULTS

Bezafibrate treatment was associated with significantly greater reductions over 3 years in median serum triglyceride (-32 vs. 4%, P = 0.001), total cholesterol (-7 vs. -0.3%, P = 0.004), and total-to-HDL cholesterol ratio (-12 vs. -0.0%, P = 0.001), and an increase in HDL cholesterol (6 vs. -2%, P = 0.02) as compared with placebo. There was a trend toward a greater reduction of fibrinogen (-18 vs. -6%, P = 0.08) at 3 years. No significant differences between the two groups were found in the progress of ultrasonically measured arterial disease. In those treated with bezafibrate, there was a significant reduction (P = 0.01, log-rank test) in the combined incidence of Minnesota-coded probable ischemic change on the resting ECG and of documented myocardial infarction.

CONCLUSIONS

Improving dyslipidemia in type 2 diabetic subjects had no effect on the progress of ultrasonically measured arterial disease, although the lower rate of "definite CHD events" in the treated group suggests that this might result in a reduction in the incidence of coronary heart disease.

ACP Broad Sheet no 151: September 1997. Investigation of dyslipidaemias

Images

Lipid peroxidation, antioxidant status and troponin-T following cardiopulmonary bypass. A comparison between intermittent crossclamp with fibrillation and crystalloid cardioplegia

OBJECTIVE

Intermittent crossclamp with fibrillation affords equivalent myocardial protection to cold crystalloid cardioplegia in patients undergoing elective coronary artery surgery. This study is a direct comparison between the two techniques with regards to free radical activity.

METHODS

The study design was part of a prospective randomised trial. We studied 24 consecutive patients with ejection fraction of 30% or greater undergoing elective coronary artery surgery. Patients were randomised into two groups. In group 1 (n = 13) the myocardium was protected by intermittent aortic cross clamping with fibrillation and group 2 (n = 11) by antegrade cold crystalloid cardioplegia. The determinants of free radical activity were serial peripheral venous samples for lipid peroxidation and plasma antioxidant status (before and at 1, 6, 24 and 72 h after the end of cardiopulmonary bypass). The determinant of the efficacy of myocardial protection was serial peripheral venous samples of cardiac troponin-T taken at the same time intervals.

RESULTS

The groups were similar with respect to age, sex distribution, preoperative ventricular function, left main stem disease, number of grafts and bypass times. Lipid peroxidation measurements at the 1 h time point were higher than preoperative values (7.24 +/- 1.19 vs. 4.48 +/- 0.69 and 9.36 +/- 1.46 vs. 4.98 +/- 1.02 (mean +/- S.E) in groups 1 and 2, respectively (units in mmol/l) thereafter values decreased to near preoperative values by 72 h. There was no significant difference between the groups (P = 0.42). Total plasma antioxidant status values at the 1 h time point were lower than the preoperative values for all patients (1.33 +/- 0.07 vs. 1.63 +/- 0.06 and 1.42 +/- 0.07 vs. 1.63 +/- 0.05 (mean +/- standard error) in groups 1 and 2, respectively, (units in mmol/l) and thereafter at the subsequent time points increased but never attained their preoperative value. There was no statistically significant difference between the two groups (P = 0.59). Troponin-T measurements showed no significant difference between the two groups at all time points (P = 0.2217).

CONCLUSIONS

This study shows that lipid peroxidation is initially elevated and the defence mechanisms against oxygen free radicals-antioxidant status'-are depressed following cardiopulmonary bypass. The degree of oxygen free radical activity produced during ischaemia and reperfusion was similar in both types of myocardial protection employed in this study.

Fasting and postprandial lipid abnormalities in hypopituitary women receiving conventional replacement therapy

Hypopituitary patients, particularly women, have excess mortality, mostly due to vascular disease. We have studied circulating lipid and lipoprotein concentrations, fasting and over 24 h, in hypopituitary women and men and in matched controls. Firstly, 67 hypopituitary patients (36 women) and 87 normal controls (54 women) were studied after an overnight fast. Secondly, 12 patients (6 women) and 14 matched controls (7 women) were studied over 24 h of normal meals and activity. The patients were all GH deficient and were replaced with cortisol, T4, and sex hormones where appropriate, but not with GH. In the first study, circulating triglycerides, total cholesterol, high density lipoprotein (HDL) cholesterol, and low density lipoprotein (LDL) cholesterol were measured after an overnight fast. In the second study, fasting levels of apolipoprotein B, apolipoprotein A1, and lipoprotein(a) were also measured, and then circulating triglyceride and total cholesterol concentrations were measured over 24 h. Fasting concentrations of triglyceride (mean +/- SEM, 1.73 +/- 0.22 vs. 1.11 +/- 0.09 mmol/L; P = 0.0025), total cholesterol (6.45 +/- 0.25 vs. 5.59 +/- 0.21 mmol/L; P = 0.002), LDL cholesterol (4.58 +/- 0.24 vs. 3.80 +/- 0.19 mmol/L; P = 0.007), and apolipoprotein B (135 +/- 10 vs. 111 +/- 9 mg/dL; P = 0.048) were elevated in hypopituitary compared to control women. The lipid alterations were observed in older and younger women and occurred independently of sex hormone or glucocorticoid replacement. Fasting values were not significantly different in hypopituitary and control men. Patients and controls (women and men) had similar fasting HDL cholesterol, apolipoprotein A1, and lipoprotein(a) concentrations. Although the differences that existed in fasting lipid values were most marked in women, the men were also abnormal in this respect, in that a higher proportion of hypopituitary than control men had total and LDL cholesterol above recommended values (> or = 6.2 and > or = 4.1 mmol/L, respectively). In the postprandial period (0730-2030 h), the areas under the curve (AUC) for circulating triglyceride and total cholesterol were significantly higher in hypopituitary than control women (P = 0.0089 and P = 0.0016, respectively). The AUC for triglyceride and total cholesterol over 24 h were also significantly increased (P = 0.009 and P = 0.0004, respectively). No significant differences were observed for postprandial and 24-h AUC for triglyceride and total cholesterol concentrations in men. We conclude that hypopituitarism with conventional replacement therapy is associated with unfavorable fasting and postprandial lipid and lipoprotein concentrations, particularly in women. The changes may contribute to the observed increased vascular morbidity and mortality.

Elevated leptin concentrations in growth hormone-deficient hypopituitary adults

BACKGROUND

Hypopituitarism with growth hormone (GH) deficiency is associated with obesity characterized by central (abdominal) distribution of fat. Recent work has demonstrated that leptin, a product of obese gene, is raised in obesity.

OBJECTIVE

To study circulating leptin levels in GH-deficient hypopituitary adults and to investigate its anthropometric, gender and metabolic relations.

METHODS

After an overnight fast of 10-12 hours, anthropometric parameters and body composition were measured and blood was collected for the measurement of circulating leptin, glucose, intact insulin, proinsulin, IGF-I, total cholesterol, triglycerides, high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol.

SUBJECTS

Fifteen (7 men) GH-deficient hypopituitary adults (maximum stimulated serum GH to provocative testing < 6 mU/l) and 21 (10 men) normal control subjects matched for age, gender and body mass index (BMI).

RESULTS

Fasting serum leptin was significantly higher in hypopituitary patients than controls (12.0 +/- 1.8 vs 8.0 +/- 1.5 micrograms/l, P = 0.04). The increase was more marked in obese (BMI > 26.0 kg/m2) patients compared with obese controls (15.3 +/- 2.0 vs 8.8 +/- 2.3 micrograms/l, P = 0.03) than in lean patients and controls. Obese control women and men had higher leptin levels than non-obese (women, 16.6 +/- 2.7 vs 8.6 +/- 0.6 micrograms/l, P = 0.03; men, 4.9 +/- 0.5 vs 2.9 +/- 0.6 micrograms/l, P = 0.035). Similar changes were observed for obese versus non-obese patients, although the changes did not reach statistical significance. Women in each group had significantly higher leptin concentrations than men (patients: 15.5 +/- 2.3 vs 7.3 +/- 1.4 micrograms/l, P = 0.009; controls: 12.6 +/- 2.4 vs 4.3 +/- 0.5 micrograms/l, P = 0.0001). These gender differences remained significant even when expressed in relation to BMI (patients: 0.57 +/- 0.09 vs 0.26 +/- 0.05 ng.m2/ml.kg, P = 0.009; controls: 0.43 +/- 0.05 vs 0.16 +/- 0.02 ng.m2/ml.kg, P = 0.0001). Serum leptin was positively associated with body mass index (P = 0.003), percentage body fat mass (P = 0.0001) and inversely related with age (P = 0.043). It demonstrated no relation with body weight, waist circumference, waist to hip ratio, fasting IGF-I, glucose, insulin, proinsulin, total cholesterol, triglycerides, HDL and LDL cholesterol in patients nor controls; 85% of variance in leptin was explained by a model including body mass index, gender, age and hypopituitarism.

CONCLUSIONS

Leptin concentrations are raised in GH-deficient hypopituitary adults to a greater extent than would be expected from the degree of obesity.

Dyslipidaemia is associated with insulin resistance in women with polycystic ovaries

OBJECTIVE

Polycystic ovary syndrome (PCOS) is characterized by hyperinsulinaemia and insulin resistance. Previous reports of lipid abnormalities in the syndrome have produced conflicting results which may, in part, be related to the lack of appropriate controls for the obese women with PCOS. Only one study has related lipid levels to insulin sensitivity. The objective of this study was to assess lipids and lipoproteins in women with PCOS, to compare the results with weight matched controls, and to relate the findings to indices of insulin secretion and action, and to menstrual history.

DESIGN

A cross-sectional study of insulin sensitivity and lipids in a cohort of PCO subjects compared to weight and ethnic group matched controls.

PATIENTS AND METHODS

We have therefore investigated glucose tolerance, plasma lipids and lipoproteins in 19 lean (LP) and 55 obese (OP) patients with PCO and compared the results with those in 22 lean (LC) and 15 obese (OC) control women. Insulin sensitivity was measured in the same subjects with a short insulin (0.05 U/kg i.v. insulin) tolerance test (LP, n = 18; OP, n = 20; LC, n = 19; OC, n = 11).

RESULTS

Results are expressed as mean +/- SEM or median (interquartile range). Fasting plasma glucose levels were similar in the four groups but the plasma glucose area was higher after oral glucose (75 g) in both the lean and obese PCOS groups than in their controls (LC 32.4 +/- 0.7 vs LP 35.2 +/- 1.2, P < 0.01; OC 34.7 +/- 1.8 vs OP 37.8 +/- 1.5 mmol/l/3 h, P < 0.01). Insulin sensitivity was significantly reduced in obese PCOS women (LC 196 +/- 9 vs LP 179 +/- 9, NS; OC 168 +/- 12 vs OP 133 +/- 9 mmol/l/min, P < 0.01). Total serum cholesterol levels were similar in the four groups but HDL2-cholesterol was reduced in both obese and lean PCOS (LC 0.42 (0.38-0.62), LP 0.31 (0.26-0.44), P < 0.05; OC 0.34 (0.21-0.47), OP 0.21 (0.12-0.32) mmol/l, P < 0.01). Total HDL-cholesterol was decreased significantly only in the obese PCOS group. Body mass index correlated significantly and negatively with total HDL-cholesterol and with HDL2-cholesterol levels both within the PCOS group and the control women. Using multiple regression insulin insensitivity contributes significantly beyond BMI to the low HDL-cholesterol in women with polycystic ovaries.

CONCLUSION

Polycystic ovary syndrome is associated with biochemical risk factors for premature vascular disease, which cannot be explained by obesity alone.

Relative fasting hypoinsulinaemia and ultrasonically measured early arterial disease in type 2 diabetes. The SENDCAP Study Group, St. Mary's, Ealing, Northwick Park Diabetes Cardiovascular Disease Prevention Study

Macrovasular disease is the most important cause of morbidity and mortality in Type 2 (non-insulin-dependent) diabetes. Dyslipidaemia and hyperinsulinaemia have been proposed as aetiological factors. This paper describes the interrelationships between fasting serum insulin, serum lipids, and the extent of ultrasonically measured early arterial disease in Type 2 diabetic subjects screened for entry into a prospective study set up to ascertain whether improving serum lipids can alter the progress of arterial disease in Type 2 diabetes. Measurements were made of the initima media thickness (IMT) in the carotid artery, and an arterial ultrasound score (AUS) based on appearances of both carotid and femoral arteries was calculated for 192 established Type 2 diabetic subjects, males and females, mean age 51 (range 35-66) years, median duration of diabetes 3.5 years, with no known cardiovascular disease. Multiple regression analysis showed that carotid IMT increased with age and was inversely related to serum insulin (variance accounted for, R2, = 8.8%, p = 0.0002). AUS increased with age and was related inversely to serum insulin, or to C-peptide when this was substituted in the model. In addition to age and serum insulin, AUS was positively associated with non-HDL cholesterol and negatively with HDL 3 cholesterol (R2 = 26%, p = 0.0001). Early thickening and damage to the arterial wall in Type 2 diabetes may be related to relative fasting hypoinsulinaemia.