Growth-promoting effect, biological activity, and binding of insulin in human intestinal cancer cells in culture.

The biological action and binding of insulin were tested in two human intestinal cancer cell lines originating from the duodenum (HUTU 80) and the colon (HT 29). After serum deprivation for 24 hr, insulin stimulated cell division and the incorporation of labeled precursors into RNA, protein, and DNA for both cell lines. The action on the RNA and protein was rapid and significantly different (1.5 to 2 times that of control) 1 hr after adding insulin. These effects were dose dependent, present at physiological concentration in vivo (10(-10) M), and independent of the transport of precursors. For thymidine incorporation, the stimulation was delayed up to 8 hr and culminated with cell division 20 hr later. As previously shown for HT 20, HUTU 80 cells exhibited insulin-specific binding sites. Binding of 125I-insulin was saturable; reversible; and time, temperature, and pH dependent. Scatchard analysis of the binding data of the two cell lines gave curvilinear plots. Assuming the presence of two independent binding sites, the high-affinity constants were 6 to 8 X 10(8) M-1, and the number of high-affinity receptors was similar and accounted for 2000 to 3000 receptors/cell. For both cell lines, the effect of insulin on protein and RNA synthesis was significantly different from control at 1 hr when binding reached a maximum at 37 degrees. The biological action of insulin on growth and macromolecular synthesis was dose dependent and maximum at about 10(-8) M insulin, which corresponds to 70% displacement of 125I-insulin binding. Furthermore, the binding and the biological action of proinsulin were about 2% that of native insulin in the two cell lines studied. These results show that insulin acts as a growth factor for these two cell lines and that these effects are probably mediated by the interaction of insulin with specific receptors.

Agreement and discrepancy in the evaluation of normal and diabetic oral glucose tolerance test.

Systematic analysis with a five-hour OGTT of 340 subjects representative of people likely to be examined in a center specialized in diabetes detection was performed by multiple discriminant analysis, which provides indices of discrimination for different sets of blood glucose (BG) values. The relative sensitivity and the relative specificity of six different diagnostic methods: Fajans and Conn, Wikerson, WHO, British Diabetic Association, UGDP, and European Study Group of Diabetes Epidemiology were computed, giving a quantitative determination for the degree of discrepancy in the definition of diabetes: only 48 per cent of the subjects are classified in the same way by any of the diagnostic criteria. The time(s) of sampling and the index or indices of OGTT which are the most efficient in screening diabetes were estimated from homogeneous groups of subjects universally recognized as nondiabetic (URND) or as diabetic (URD) according to the different diagnostic methods. Better discriminating power (DP) between URD and URND compared with the maximum DP as measured by D2 of Mahalanobis from the seven BG values of the OGTT is given by the two-hour (70.2 per cent) than by the one-hour (49.5 per cent) BG value when a single value is used; the one-two-hour BG value is the best set of two times (80.7 per cent). The different indices now in use for the classification of the OGTT have been found less effective than the weighted sum of one-two-hour BG values. The difficulty in obtaining highly specific diagnostic tests is discussed in relation to the consequences on a partly automated screening in large populations.

Risk factors for NIDDM in white population. Paris prospective study.

Risk factors for non-insulin-dependent diabetes mellitus (NIDDM) were assessed in a population of 5042 middle-aged white men, initially nondiabetic, who were followed 3 yr. The subjects were participants in the Paris Prospective Study I. Sixty-three subjects developed diabetes during the follow-up. Plasma glucose concentration in the years before the occurrence of the disease was a major risk factor. Subjects with normal glucose tolerance but elevated fasting plasma glucose exhibited a similar risk of developing NIDDM as did subjects classified as having impaired glucose tolerance on the basis of 2-h postload glucose. In a multiple logistic regression, a high fasting plasma insulin concentration and a low 2-h plasma insulin concentration after a glucose load in association with a high body mass index were independent predictors of conversion to NIDDM from impaired glucose tolerance. Previously, this result had been found only in Nauruans, Pima Indians, and Japanese. This demonstrates for the first time in a white population that a high fasting and low 2-h insulin concentration is predictive of conversion to NIDDM from impaired glucose tolerance.

Effect of truncated glucagon-like peptide 1 on cAMP in rat gastric glands and HGT-1 human gastric cancer cells.

We tested the truncated 7-37 glucagon-like peptide 1 (TGLP-1), a naturally occurring porcine intestinal peptide, and other members of the glucagon family, including pancreatic glucagon (G-29), GLP-1 and GLP-2 for their ability to activate the cAMP generating system in rat gastric glands and HGT-1 human gastric cancer cells. In rat fundic glands, TGLP-1 was about 100 times more potent (EC50 = 2.8 X 10(-9) M) than GLP-1 of G-29, and 10 times more potent than G-29 in the HGT-1 cell line. Our results support the notion that TGLP-1 plays a direct role in the regulation of acid secretion in rat and human gastric mucosa.

[Diabetes, hyperglycemia, hyperinsulinemia and risk of cardiovascular mortality. Findings of the Paris Prospective Survey, 10 years later]. / Diabète, Hyperglycémie, Hyperinsulinémie et risque de mortalité cardiovasculaire. Données de l'Enquête Prospective Parisienne, 10 ans après.

The Paris Prospective Study is a long-term investigation of coronary heart disease (CHD) conducted on 7038 working men, aged 43-54 years and followed 11.2 years in mean. The first examination included a 0-2 h 75 g OGTT with measurement of plasma insulin and glucose levels, beside the major CHD risk factors. 651 deaths (CHD = 126) were recorded. The annual CHD mortality rates were respectively 1.4, 2.7 and 3.5 per 1000 for the 6055 normoglycaemic, 690 impaired glucose tolerance and 293 new and known diabetic subjects (1980 WHO classification) (p less than 0.001). It showed that the fasting plasma insulin was positively associated with risk independent of the other factors (p less than 0.05), whereas glucose tolerance, including overt diabetes, was not significantly associated. Thus, high insulin levels may constitute a more sensitive predictor of CHD than the degree of glucose intolerance and it could be useful to avoid excessive insulin plasma concentration, and even to lower its levels.

A new bioassay of VIP: results in watery diarrhoea syndrome.

Cyclic AMP accumulation in human colon adenocarcinoma cells in culture (HT-29) is known to be particularly sensitive to the stimulating action of vasoactive intestinal peptide (VIP). This property was exploited as a means of investigating the possible role of VIP as a humoral mediator in the watery diarrhoea syndrome. Our results showed that plasma from two patients with watery diarrhoea syndrome associated with ganglioneuroblastoma and pheochromocytoma strongly stimulated cyclic AMP accumulation in HT-29 cells, whereas plasma from normal subjects and patients with other diarrhoeal disorders had no effect. The stimulation induced by serial dilutions of plasma from patients paralleled the VIP-induced response. Preincubation of these plasmas with specific anti-VIP antibody prevented their stimulatory effects. Plasma sampled after the arrest of diarrhoea (spontaneous or after surgical resection of tumours) elicited AMP rise in HT-29 cells. Tumour extract stimulated cyclic AMP accumulation in HT-29 cells with a dose-response curve which was superimposable on the one obtained with standard VIP. The results lend support to the hypothesis that VIP is a humoral mediator in WDS and suggest that the diarrhoea is mediated through a VIP-induced accumulation of cyclic AMP in intestinal epithelial cells.

Coronary heart disease mortality risk: plasma insulin level is a more sensitive marker than hypertension or abnormal glucose tolerance in overweight males. The Paris Prospective Study.

The Paris Prospective Study I (7434 men) is a long-term investigation of cardiovascular diseases. A previous analysis has shown that high plasma insulin level was a more sensitive marker than glucose intolerance in the prediction of coronary heart disease (CHD). In order to ascertain the risk model for CHD in relation to high circulating plasma insulin level, we studied CHD mortality rates in groups of participants to the study with similar profiles of risk factors. The risk factors considered to cross-classify the subjects were: serum cholesterol level, blood pressure, fasting plasma insulin level (all the significant predictors of CHD mortality in the Cox regression model), plus body mass index (BMI) and 2-h post-load blood glucose level. Serum cholesterol level was linearly related to CHD mortality risk. The strength of the association of blood pressure to the risk was reduced when BMI increased. By contrast, the association of blood pressure to the risk remained linear when plasma insulin level rather than BMI was considered. Plasma insulin level was a more sensitive marker of CHD risk than glucose intolerance in the overweight group. Moreover, in this group, the relation to CHD mortality risk was stronger for plasma insulin level than for blood pressure.

Coronary heart disease mortality in relation with diabetes, blood glucose and plasma insulin levels. The Paris Prospective Study, ten years later.

The Paris Prospective Study is a long-term investigation of cardiovascular diseases in a population of 7164 working men, aged 43-54 years. The first annual follow-up session (1968-73) included a 0-2 hr 75 g OGTT with measurement of plasma insulin and glucose levels beside the major coronary heart disease (CHD) risk factors: arterial pressure, cigarette smoking, weight, cholesterol, triglycerides. After a mean 11.2 years follow-up, 651 deaths, among them 126 due to CHD, were recorded. The annual CHD mortality rates were respectively 1.4, 2.7 and 3.2 per 1000 for the 6055 normoglycaemic, 690 impaired glucose tolerance, and 293 new and known diabetic subjects (1980 WHO classification) (p less than 0.01). The annual risk was analyzed by the multivariate Cox model. It showed that the fasting plasma insulin was positively associated with risk independent of the other factors (p less than 0.05), whereas glucose tolerance, including overt diabetes, was not significantly associated. We conclude that high insulin levels may constitute a more sensitive predictor of CHD than the degree of glucose intolerance, it could be useful to avoid excessive insulin plasma concentration, and even to lower its level.

Hyperinsulinaemia as a predictor of coronary heart disease mortality in a healthy population: the Paris Prospective Study, 15-year follow-up.

The Paris Prospective Study is a long-term, large-scale study of the factors predicting coronary heart disease. The first follow-up examination included, for subjects not known as having diabetes mellitus, a 75 g oral glucose tolerance test with measurement of plasma insulin and glucose levels, fasting and 2 h post-load. Between 1968 and 1973, 6903 men aged 43-54 years were thus examined. Causes of death were ascertained within this group after 15 years of mean follow-up. The baseline variables were tested as predictors of death from coronary heart disease by a Cox regression analysis. Significant independent predictors of coronary heart disease death were: systolic blood pressure, number of cigarettes per day, plasma cholesterol level, and 2 h post-load plasma insulin level when entered as a categorical variable (below or above 452 pmol/l. i.e. the lower limit of the fifth quintile of the distribution). This dichotomization was performed to account for the non-linear univariate distribution of deaths with increasing post-load insulin values. Fasting plasma insulin level was not an independent predictor of death by coronary heart disease over this long-term follow-up. Levels of blood glucose were not significant independent predictors of death by coronary heart disease when plasma insulin levels were included in the model. The same applied to abnormalities of glucose tolerance when the 125 men with known non-insulin-treated diabetes at baseline were added to the group. Under the assumption that hyperinsulinaemia is a marker of insulin resistance, the results are consistent with the hypothesis that insulin resistance is associated with a higher risk of coronary heart disease mortality. However, it is doubtful that circulating insulin per se is a direct cause of arterial complications.

Hypertriglyceridaemia as a risk factor of coronary heart disease mortality in subjects with impaired glucose tolerance or diabetes. Results from the 11-year follow-up of the Paris Prospective Study.

The Paris Prospective Study is a long-term investigation of the incidence of coronary heart disease in a large population of working men. The first follow-up examination involved 7,038 men, aged 43-54 years. Subjects with impaired glucose tolerance or diabetes (n = 943) were selected from the total population for a separate analysis of coronary heart disease mortality risk factors. During a mean follow-up of 11 years, 26 of these 943 subjects with abnormal glucose tolerance died from coronary heart disease. Univariate analysis showed that plasma triglyceride level (p less than 0.006), plasma cholesterol level (p less than 0.02), and plasma insulin level both fasting and 2-h post-glucose load (p less than 0.02), were significantly higher in subjects who died from coronary heart disease compared to those who did not. In multivariate regression analysis using the Cox model, plasma triglyceride level was the only factor positively and significantly associated with coronary death. The distribution of plasma triglyceride levels was clearly higher for the subjects who died from coronary heart disease compared to those who did not die from this cause or were alive at the end of the follow-up. This new epidemiological evidence that hypertriglyceridaemia is an important predictor of coronary heart disease mortality in subjects with impaired glucose tolerance or diabetes suggests a possible role of dyslipidaemia in the excessive occurrence of atherosclerotic vascular disease in this category of subjects.

The role of non-esterified fatty acids in the deterioration of glucose tolerance in Caucasian subjects: results of the Paris Prospective Study.

Although an increased plasma non-esterified fatty acid (NEFA) concentration has been shown to increase insulin resistance (Randle cycle), decrease insulin secretion and increase hepatic gluconeogenesis, the effect of NEFA on the deterioration of glucose tolerance has not been studied prospectively in Caucasian subjects. Therefore, we investigated whether plasma NEFA may be regarded as predictors of deterioration of glucose tolerance in subjects with normal (NGT, n = 3671) or impaired (IGT, n = 418) glucose tolerance who were participants in the Paris Prospective study. The subjects were first examined between 1967 and 1972 and underwent two 75-g oral glucose tolerance tests 2 years apart with measurements of plasma glucose, insulin and NEFA concentrations. Glucose tolerance deteriorated from NGT to IGT or non-insulin-dependent diabetes (NIDDM) in 177 subjects and from IGT to NIDDM in 32 subjects. In multivariate analysis, high fasting plasma NEFA in NGT subjects and high 2-h plasma NEFA and low 2-h plasma insulin concentrations in IGT subjects were significant independent predictors of deterioration along with older age, high fasting and 2-h plasma glucose concentrations and high iliac to thigh ratio. When subjects were divided by tertiles of plasma NEFA concentration at baseline, there was an increase in 2-h glucose concentration with increasing NEFA in the subjects who did not deteriorate, but no effect of plasma NEFA in those who deteriorated. In subjects with IGT who deteriorated compared with those who did not 2-h plasma insulin concentration was lower but there was no evidence that this resulted from an effect of plasma NEFA. Our data suggest that a high plasma NEFA concentration is a risk marker for deterioration of glucose tolerance independent of the insulin resistance or the insulin secretion defect that characterize subjects at risk for NIDDM.