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Biomedical subjects

G Riccardi

Publications and source records attributed to G Riccardi.

At least 145 records · Page 8Linked to original sources
PubMed1988

Polymorphism at the 5' end flanking region of the insulin gene is associated with reduced insulin secretion in healthy individuals.

Sixty-four unrelated healthy subjects were studied for the detection of a DNA polymorphism at the 5' end of the insulin gene. No significant difference between the groups was found in blood glucose values at fasting and after an oral glucose load. A significant association was found between fasting (P less than 0.05) and after load plasma C-peptide levels (P less than 0.01) and the presence of a 1.6 Kb insertion at the 5' end of the insulin gene. A gene dose-dependent effect was noted, class 3/3 individuals having the lowest after-load C-peptide concentration and class 1/3 an intermediate level (F for the linear trend: P = 0.007). This might suggest that insulin gene polymorphism affects insulin secretion in healthy individuals. In order to confirm this, a subgroup of six class 3/3 and eight class 1/1 individuals subsequently underwent a hyperglycaemic clamp. The tissue sensitivity to insulin was similar in the two groups but glucose-stimulated insulin secretion was markedly impaired in homozygotes for the class 3 allele. In this group, insulin secretion was, on average, only one-third of that in class 1/1 individuals (P less than 0.02). Similarly impaired in class 3/3 persons was the glucose + arginine-stimulated insulin secretion (P less than 0.05). We conclude that the polymorphism at the 5' end of the insulin gene is associated with variations in insulin secretion in healthy humans.

Adult↗
PubMed1988

Relationships between anaerobic threshold and exercise hemodynamic pattern in patients with previous myocardial infarction.

UNLABELLED: In 78 male class I and II NYHA patients with previous myocardial infarction, the relationships between ventilatory anaerobic threshold levels and hemodynamic patterns during a maximal symptom-limited stress test in the supine position were studied. Among the 36 patients with abnormal exercise wedge values, 11 showed an anaerobic threshold (AT) less than 35% of the maximal predicted VO2(mpVO2) (group A) and 23 showed an AT of 36-50% mpVO2 (group B). In 2 patients, the AT was greater than 50% mpVO2. Among the 42 patients with normal exercise wedge pressure, 13 showed an AT of 36-50% mpVO2 (group C), whereas in 29 patients, the AT was greater than 50% mpVO2 (group D). The mean value of AT in group A was significantly lower than in group B (8.6 +/- 0.7 vs. 11.7 +/- 0.5 ml/kg.min; p less than 0.05). No difference was found in the mean of the AT between groups B and C, while the mean value of AT in group D was significantly higher than in group C (16.9 +/- 0.4 vs. 12.9 +/- 0.6 ml/kg.min; p less than 0.005). No significant differences between groups C and D were found in the invasive and noninvasive parameters considered. Groups C and D were statistically different from groups A and B for pulmonary capillary pressures, total pulmonary resistances, stroke indexes, heart rates, arteriovenous O2 differences, total systemic resistances and lactate concentrations. Total pulmonary resistances and heart rates were statistically higher and stroke indexes were statistically lower in group A than in group B. IN CONCLUSION: (1) patients with normal exercise wedge values show a higher AT than patients with abnormal exercise wedge values. (2) Patients with normal exercise hemodynamic patterns classified according to their AT show no difference in hemodynamics; in these patients the level of AT seems to be related to peripheral determinants. (3) Patients with abnormal exercise hemodynamic patterns classified according to their AT level show different hemodynamics and different responses in ventricular function; in these patients the level of AT seems to be related to the cardiac impairment.

Adult↗
PubMed1988

Quantitation of forearm glucose and free fatty acid (FFA) disposal in normal subjects and type II diabetic patients: evidence against an essential role for FFA in the pathogenesis of insulin resistance.

This study was designed to quantitate glucose and FFA disposal by muscle tissue in patients with type II diabetes and to investigate the relationship between FFA metabolism and insulin resistance. The forearm perfusion technique was used in six normal subjects and two groups of normal weight diabetic patients, i.e. untreated (n = 8) and insulin-treated (n = 6). The latter received 2 weeks of intensive insulin therapy before the study. Plasma insulin levels were raised acutely [950-1110 pmol/L) (130-150 microU/mL)], while the blood glucose concentration was clamped at its basal value [4.9 +/- 0.1 (+/- SE) mmol/L in the normal subjects, 5.7 +/- 0.5 in the insulin-treated diabetic patients, and 5.5 +/- 0.3 in the untreated diabetic patients] by a variable glucose infusion. During the control period, arterial FFA concentrations were similar in the three groups, and they decreased to a comparable extent (less than 0.1 mmol/L) in response to insulin infusion. During the control period, the mean forearm FFA uptake was 2.5 +/- 0.5 mumol/L.min in the normal subjects, 2.9 +/- 0.5 in the insulin-treated patients, and 2.1 +/- 0.5 in the untreated diabetic patients. During the insulin infusion, FFA uptake was profoundly suppressed to similar levels in the normal subjects (0.9 +/- 0.1 mumol/L.min), the insulin-treated diabetic patients (1.1 +/- 0.3), and the untreated diabetic patients (0.9 +/- 0.1; P less than 0.001). Forearm glucose uptake was similar in the three groups during the control period. It increased during the insulin infusion, but the response in both diabetic groups was less than that in the normal subjects. The total amounts of glucose taken up by the forearm during the study period were 5.2 +/- 0.7, 2.6 +/- 0.5, and 2.1 +/- 0.6 mmol/L.min in the normal subjects, the insulin-treated diabetic patients, and the untreated diabetic patients, respectively (P less than 0.01). We conclude that 1) insulin-mediated glucose uptake by forearm skeletal muscle is markedly impaired in type II diabetes and improves only marginally after 2 weeks of intensive insulin therapy; 2) in contrast, no appreciable abnormality in forearm FFA metabolism is demonstrable in insulin-treated type II diabetic patients; and 3) FFA do not contribute to the insulin-treated skeletal muscle insulin resistance that occurs in patients with type II diabetes mellitus.

Adult↗
PubMed1988

[Reproducibility of ergometric parameters at the ischemic threshold: study of 160 patients with effort coronary insufficiency].

To assess the reproducibility of ergometric parameters at the ischemic threshold, 160 patients, with coronary artery disease and exercise-induced S-T segment depression (102 with previous AMI), were evaluated by means of two control exercise tests performed, in pharmacological wash-out, on different days within 48 hours. The mean values of work load (WL), heart rate (HR) and double product (DP) did not show any statistical difference between the two exercise tests at 0.1 mV S-T depression (ischemic threshold), recorded by a computer assisted electrocardiograph system (Marquette CASE); on the contrary blood pressure (BP) slightly, but significantly (p less than 0.05) decreased at the second test (173.9 +/- 27.2 vs 179.8 +/- 25.8). The variability of the DP values in each subject at 0.1 mV S-T depression, expressed as numerical (delta) and percentage (delta %) differences, exhibited normal distributions. The delta DP showed a mean +/- 1 SD of -157.5 +/- 3271.5 beats x mmHg/min and the delta % DP a mean of +/- 1 SD of 1.46 +/- 16.4%. The values within a standard deviation from the mean (from +3114 to -3429 when numerical differences and from +17.8 to -14.9 when percentage differences) were used for defining the reproducibility of the ischemic threshold. No correlation was found between the delta % DP and the percentage differences in work load at the ischemic threshold. So, DP being more strictly related to MVO2, appears more apt in defining the ischemic threshold reproducibility. A good correlation (r = 0.821) was found between delta DP and delta % DP.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1988

Very low density lipoprotein. Qualitative abnormalities in patients with premature coronary heart disease and in patients with insulin dependent diabetes.

VLDL composition has been investigated in two groups of patients: one with Premature Coronary Heart Disease (PCHD) and another one with Insulin Dependent Diabetes Mellitus. Both groups showed abnormal VLDL composition. PCHD patients had VLDL significantly enriched in free cholesterol and triglycerides in comparison with a group of controls matched with patients for sex, age, BMI, serum cholesterol and TG. This VLDL composition indicates a prevalence of big particles, which can be found at the beginning of the lipolytic cascade. On the other hand VLDL of diabetic patients were enriched in cholesterol, especially esterified cholesterol, and apo B in comparison with the respective control group suggesting an increase of smaller VLDL, considered more atherogenic. In conclusion these two studies demonstrate that VLDL compositional abnormalities can be found in two different groups of patients even in the absence of hyperlipidemia.

Adult↗
PubMed1987

[Miocamycin in the prevention and treatment of cutaneous infections in the emergency service].

The efficacy and tolerability of a new macrolide, Myocamycine, were assessed in the anti-infectious prophylaxis of lacerations and contusions and in the treatment of already infected wounds or phlegmons. A total of 175 patients were treated. Side effects induced the suspension of treatment in 8% of cases while the drug proved effective in preventing the infection of wounds at risk in 98% and curing existing infections in 100%.

Adolescent↗
PubMed1987

Haemodynamic effects of diltiazem at rest and during exercise in patients with previous myocardial infarction.

A single blind study between placebo and diltiazem (25 mg i.v. single dose) was carried out on 20 male patients with previous myocardial infarction and without exertional ischaemia. Patients, 50 +/- 6.1 (mean +/- SD) years of age, underwent a right heart catheterization with Seldinger's percutaneous approach and brachial or radial artery percutaneous catheterization. Haemodynamic variables were recorded in the supine position after catheterization in baseline conditions at rest, after a warming-up period of 6 min, before and after a first and second exercise test with stepwise increments of 25 W per 3 min. Before the second exercise test, either placebo or diltiazem (25 mg) was injected intravenously in 3 min. In comparison with placebo, diltiazem significantly reduced resting blood pressure (P less than 0.001) and systemic vascular resistance (P less than 0.001) and increased cardiac index (P less than 0.01); during exercise it also reduced the mean pulmonary arterial pressure (P less than 0.05), pulmonary wedge pressure (P less than 0.05), total pulmonary resistance (P less than 0.02), and increased the stroke volume (P less than 0.05). The present study demonstrated that intravenous diltiazem did not induce a significant rise in cardiac index but reduced the afterload and slightly reduced the preload. Diltiazem also reduced myocardial oxygen consumption and decreased blood pressure, mean right atrial pressure and slightly decreased the heart rate.

Cardiac Catheterization↗
PubMed1987

The use of diet to lower plasma cholesterol levels.

The basic principle of a lipid lowering diet is restriction of saturated fat intake. This can be achieved by reducing the consumption of dairy products and fats of animal origin. To keep energy intake constant (in normal weight individuals) complex carbohydrate or unsaturated fat is substituted for saturated fat. Diets with various proportions of complex carbohydrate, monounsaturated fatty acids, and polyunsaturated fatty acids have been proposed. In theory, the latter should be the best substitute for saturated fatty acids in a lipid lowering diet. Polyunsaturated fat has cholesterol lowering activity that is additive to the effect obtained by reducing the amount of dietary saturated fat. In practice, either polyunsaturated fatty acids or monounsaturated fatty acids or complex carbohydrate exert very similar effects on plasma cholesterol levels when substituted for saturated fatty acids in a lipid lowering diet. Their effects on plasma triglyceride are, however, dissimilar. Increased consumption of polyunsaturated fat leads to pronounced reduction in plasma triglyceride concentrations. Conversely, a high carbohydrate diet has a hypertriglyceridemic effect that is more pronounced in individuals with diabetes or preexisting hypertriglyceridemia. Dietary cholesterol should also be reduced in order to lower plasma cholesterol levels. However, the hypocholesterolemic effect of this measure has a large interindividual variation which is further influenced by the fat composition of the diet. Dietary fibre has received attention in more recent years for its ability to reduce plasma cholesterol levels. Fibre rich foods are not equally effective in this respect, the most active being legumes, fruit and vegetables. When high carbohydrate-high fibre diets are consumed, the hypertriglyceridaemic effect of carbohydrate is counteracted by dietary fibre.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol↗
PubMed1987

Variable threshold of exertional ischaemia in patients with positive exercise test at low workload.

In order to determine individual variability of ischaemic threshold on different days, 18 patients with exertional ischaemia at low workload were studied. All patients performed two exercise tests during different days in the morning and three on the same day at 9 am, 2 pm and 5 pm. The test performed in the morning on different days resulted in a significant difference in the mean values of rate pressure product at the ischaemic threshold as a consequence of individual variability observed in 10 patients. In 8 of these patients the differences were greater than 4000 mmHg beats min-1. Two patients showed respectively, 1 and 5 negative exercise tests despite the greater values of rate pressure product reached. Only 3 patients showed circadian variation of the ischaemic threshold; in these 3 patients variations of rate pressure product at the ischaemic threshold were also observed between different days. These data indicate that in patients with exertional ischaemia at low workload the rate pressure product at the ischaemic threshold shows considerable variability between tests performed on different days.

Angina Pectoris↗
PubMed1986

Direct evidence for a stimulatory effect of hyperglycemia per se on peripheral glucose disposal in type II diabetes.

The effect of hyperglycemia per se on glucose uptake by muscle tissue was quantitated in six controls and six type II diabetics by the forearm technique, under conditions of insulin deficiency induced by somatostatin (SRIF) infusion (0.7 mg/h). Blood glucose concentration was clamped at its basal value during the first 60 min of SRIF infusion and then raised to approximately 200 mg/dl by a variable glucose infusion. Plasma insulin levels remained at or below 5 microU/ml during SRIF infusion, including the hyperglycemic period. No appreciable difference between controls and diabetics was present in the basal state as to forearm glucose metabolism. After 60 min of SRIF infusion and euglycemia, forearm glucose uptake fell consistently from 2.1 +/- 0.7 mg X liter-1 X min-1 to 1.0 +/- 0.6 (P less than 0.05) and from 1.7 +/- .2 to 0.4 +/- 0.3 (P less than 0.02) in the control and diabetic groups, respectively. The subsequent induction of hyperglycemia caused a marked increase in both the arterial-deep venous blood glucose difference (P less than 0.02-0.01) and forearm glucose uptake (P less than 0.01-0.005). However, the response in the diabetic group was significantly greater than that observed in controls. The incremental area of forearm glucose uptake was 276 +/- 31 mg X liter-1 X 90 min and 532 +/- 81 in the control and diabetic groups, respectively (P less than 0.02). In the basal state, the forearm released lactate and alanine both in controls and diabetic subjects at comparable rates. No increment was observed after hyperglycemia, despite the elevated rates of glucose uptake. It is concluded that (1) hyperglycemia per se stimulates forearm glucose disposal to a greater extent in type II diabetics than in normal subjects; and (2) the resulting increment of glucose disposal does not accelerate the forearm release of three carbon compounds. The data support the hypothesis that hyperglycemia per se may play a compensatory role for the defective glucose disposal in type II diabetes.

3-Hydroxybutyric Acid↗
PubMed1986

Platelet fibrinogen binding in diabetes mellitus. Differences between binding to platelets from nonretinopathic and retinopathic diabetic patients.

While it is known that platelets from diabetic patients bind more fibrinogen than do platelets from normal subjects, there has been no study comparing this phenomenon in platelets from nonretinopathic and retinopathic patients. We have made such a comparison and have found the following. In agreement with previous reports, platelets from nonretinopathic diabetic patients bind abnormally high amounts of fibrinogen. No differences in the amount of fibrinogen bound to platelets (stimulated by collagen or thrombin) were found when data from nonretinopathic and retinopathic patients were compared. However, while aspirin (an inhibitor of thromboxane synthesis) reduced the abnormally high fibrinogen binding of platelets from nonretinopathic patients to normal control levels, it did not normalize the high fibrinogen binding of platelets from retinopathic diabetic patients. The combination of aspirin plus apyrase (an ADP scavenger) almost suppressed fibrinogen binding and aggregation of platelets from normal or nonretinopathic diabetic subjects, whereas it had a somewhat lesser effect on binding and aggregation of platelets from retinopathic subjects. By using a monoclonal antibody (B59.2) to the platelet receptor for fibrinogen, we determined that this receptor was the same in platelets from normal as well as nonretinopathic diabetic subjects and that this antibody could suppress the binding of fibrinogen and the aggregation of platelets from both types of patients just as it did in platelets from normal subjects. Thus, our data indicate that, while platelets from both retinopathic and nonretinopathic patients are hyperaggregable and show abnormally high binding of fibrinogen, they differ in that these abnormalities can be normalized in platelets from nonretinopathic patients by suppressing prostaglandin/thromboxane formation and scavenging ADP, but not in those from retinopathic patients.

Adolescent↗