Plasma nitric oxide concentrations are elevated in insulin-resistant healthy subjects.

The goal of this study was to compare plasma nitric oxide (NO) concentrations in healthy subjects, defined as either insulin-resistant or insulin-sensitive on the basis of the plasma insulin response to a 75-g oral glucose challenge. For this purpose, 404 healthy subjects were divided into quartiles on the basis of the plasma insulin response to glucose, and 49 individuals were selected from the quartile with the lowest insulin response and 49 from the quartile with the highest insulin response. The two groups of 49 each were selected to be essentially identical in terms of age, gender distribution, body mass index (BMI), and waist to hip ratio (WHR). The quartile with the greatest insulin response also had a significantly higher plasma glucose response to oral glucose, faster heart rate, higher blood pressure, and the combination of higher triglyceride and lower high-density lipoprotein (HDL) cholesterol concentrations. In addition to the latter changes, previously shown to be associated with hyperinsulinemia, NO concentrations were also higher in the hyperinsulinemic group. It is speculated that this increase in the NO concentration in hyperinsulinemic and presumably insulin-resistant, subjects represents a compensatory effort to overcome the untoward effects of insulin resistance and/or hyperinsulinemia.

Heavy metals in atmospheric surrogate dry deposition

This paper describes a methodological approach for the assessment of the amount of surrogate dry deposition of several toxic heavy metals (Cd, Cr, Cu, Ni, Pb, V, Zn) associated with atmospheric particulate matter at ground level. The objectives of the study were twofold: i) the evaluation of several techniques for the digestion of dry deposition samples for trace metal analysis; ii) the comparison of the results from two samplers with different collecting surfaces. A dry solid surface sampler (DRY sampler, Andersen--USA) and a water layer surface sampler (DAS sampler--MTX Italy) were employed. The samples were collected over a one-year period in an urban site of Bologna (northern Italy). A description is given of the complete procedure, from sampling to data elaboration, including sample storage, digestion and analytical methods. According to the results obtained with three different digestion techniques (Teflon bomb, microwave digester and Teflon flask with vapour cooling system), the highest recovery rate was achieved by the Teflon bomb procedure employing an NBS 1648 Standard Reference Material; 90-95% of the elements considered were recovered by dissolution in a pressurized Teflon bomb with an HNO3-HF mixture. Given these results, the technique was adopted for dry deposition sample digestion. On the basis of the amount of heavy metals measured as monthly deposition fluxes (microg/m2), the collecting efficiency of the DAS sampler for a number of elements was found to be as much as two to three times greater than that of the DRY sampler.

Dissociation between urinary albumin excretion and variables associated with insulin resistance in a healthy population.

OBJECTIVES: To see if the cluster of metabolic and haemodynamic variables defined as comprising Syndrome X varied as a function of urinary albumin excretion (UAE) rate in a healthy population. DESIGN: A cross-sectional, population-based study. SETTING: A factory in Italy. SUBJECTS: Two hundred and twenty-five healthy volunteers, 115 men and 110 women. OUTCOME MEASURES. Measurements were made of the plasma glucose and insulin responses to oral glucose, fasting triglyceride (TG) and high density lipoprotein (HDL)-cholesterol concentrations, blood pressure, and UAE rates. RESULTS: Only five of the 225 volunteers had micro-albuminuria, defined as a UAE rate > 2 micrograms min-1, and the UAE rate was < 5 micrograms min-1 in 80% of the volunteers. Significant variations in the metabolic and haemodynamic variables measured were not associated with any differences in UAE. Finally, significant relationships were found between various measures of plasma insulin concentration and plasma glucose response to oral glucose, plasma TG and HDL-cholesterol concentrations, and mean arterial blood pressure, independent of variations in age, body mass index, ratio of waist-to-hip girth, and UAE rates. CONCLUSION: The widespread variability in plasma glucose and insulin responses, plasma TG and HDL-cholesterol concentrations, and blood pressure that are seen in the population at large cannot be attributed to variations in UAE rate.

[Severe diabetic retinopathy and renal function in non-insulin-dependent (type-2) diabetes mellitus]. / Retinopatia diabetica ingravescente e funzionalità renale nel diabete mellito non insulino-dipendente (tipo 2).

The existence of a linkage between retinal and renal microvascular complications in type 2 diabetes has been so far little investigated. For this purpose we evaluated the presence and degree of renal dysfunction in the most serious clinical conditions of diabetic retinopathy. On the basis of the alterations evidenced by fluorescein angiography 73 type 2 diabetic patients were recruited and divided into the following groups: 19 patients were affected by "clinically significant" Macular Edema (ME), 25 subjects had Preproliferative Retinopathy (PrePR) and 29 patients showed Proliferative Retinopathy (PR). Mean values (M +/- SD) of glycosylated hemoglobin, plasma basal C-peptide, lipid profile, blood pressure, glomerular filtration rate, body mass index, age and known duration of diabetes were similar between the groups. Urinary albumin excretion rate (UAE) was determined for each patient on three consecutive overnight collections (pg/min). Even though the distribution of normo (UAE < 20 micrograms/min), micro (UAE:20-200) and macroalbuminuric (UAE > 200) patients did not significantly differ between the groups, mean values of UAE increased significantly in PrePR (371.1 +/- 532.2) and PR (300.7 +/- 717.3) with respect to ME (35.4 +/- 73.1; p < 0.05). The evaluation of all patients recruited for the study, independently of the kind of retinal alteration, showed that 56.8% of them had no sign of even incipient renal dysfunction, in spite of the advanced retinal damage. When considering those patients affected by both retinal and renal complications (43.2%) the prevalence of renal involvement resulted different in the three conditions investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Naloxone does not alter the effect of gamma aminobutyric acid derivative, baclofen, on GH release in man.

To evaluate the interaction between opioid peptides and GABAergic system in regulating GH secretion we administered 5 mg of baclofen, a GABA derivative, to eight normal male subjects. The results were compared to those obtained in the same subjects treated with naloxone (10 mg/2 h) plus baclofen. GH levels increased significantly above basal value either after baclofen and naloxone plus baclofen without any significant difference between GH responses during the two tests. It is suggested that the two substances do not act at the level of the same receptor site. The evaluation of a possible interaction between opioid peptides and GABAergic system on GH release requires further investigation.

[The effects of digoxin administration on normal and pathological sinus node function. An electrophysiological study (author's transl)]. / Effetti della digitale sulla funzionalita' sinusale normale e patologica. Studio elettrofisiologico.

In 12 normal subjects (group I), in 12 subjects with asymptomatic sinus bradycardia (group II) and in 18 patients with symptomatic sick sinus syndrome (group III), sinus node cycle length (SNCL), sinus node recovery time (SNRT), corrected sinus node recovery time (CSNRT), sino-atrial conduction time (SACT), have been evaluated before and after an acute digoxin administration. Mean value of SNCL lengthened significantly in all groups. Mean value of SNRT increased moderately in the first group, remarkably in the third group, whereas it showed a mild but statistically insignificant increase in the second group. Mean value of CSNRT was significantly lengthened only in the third group. Mean value of SACT showed a mild but statistically insignificant lengthening in all groups. In order to investigate the importance of the parasympathetic action induced by digitalis, in 4 normal subjects, in 4 patients with asymptomatic sinus bradycardia, and in 10 patients with symptomatic sick sinus syndrome, SNCL, CSNRT and SACT has been evaluated after an intravenously, administration of atropine, following digoxin. In the paper the intricate mechanisms by which digitalis affects the parameters of sinus nodal function especially in patients with symptomatic sick sinus syndrome, are discussed. In disagreement with the mot papers reported in the literature we think that an acute digoxin administration is able to worsen the electrophysiological parameters of sinus nodal function especially in patients with symptomatic sick sinus syndrome.

[The atrial vectorcardiogram at rest and during exercise. Comparison, by computerized analysis, of normal subjects and patients with mitral stenosis]. / Vettorcardioramma atriale a riposo e durante esercizio. Confronto, mediante analisi computerizzata, fra soggetti normali e pazienti con stenosi mitralica.

This study on rest and exercise atrial vectorcardiogram (Frank method) was carried out on a group of 27 healthy volunteers (Group A) and on a group of 24 patients with mitral stenosis (Group B). All 51 subjects were women. Our original program was performed using a Hewlett Packard 2100 computer. The pattern recognition of every wave was carried out by analysing a particular function obtained by translating the X, Y, Z leads on the line joining the T-P, P-Q, ST segments. In the group B on rest a significant correlation between atrial vectorcardiogram parameters and pulmonary capillary wedge pressure was not present. Between both group A and B the vectorcardiographic data were greatly superposables. It is difficult, because of the great interindividual variability of results obtained, to have very discriminant vectorcardiographic parameters between group A and group B on rest and during exercise, performed in the supine position with a bicycle ergometer. In the both groups A and B the exercise induces a significant increase of spatial magnitude of maximal P xyz vector (max P xyz) and maximal P amplitude on frontal and sagittal planes, with P loop shifting towards a vertical position. The following significant results were observed only in group B of mitral patients: 1) an increase of P wave duration; 2) an increase of the interval between the two peaks of P wave (measurable only in group B); 3) an increase in the amplitude and backward rotation of max P xyz azimuth and of the maximal vector backward directed on horizontal (H) plane; 4) an increase of P loop linear, tangential and areolar velocities. The P loop anterior and posterior area on H plane and of the spatial P xyz vectors changes during exercise were directionally similar in the normal group and in the patients with mitral stenosis. These results suggest a little diagnostic power of the P wave area changes during exercise. In both groups maximal atrial T vector increases with exertion, but only in group B migrates backward on H plane, suggesting an atrial gradient directed towards the left atrium.