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Biomedical subjects

A Masoni

Publications and source records attributed to A Masoni.

At least 19 recordsLinked to original sources
PubMed1995

The natural history of kyphosis in postmenopausal women.

A cross-sectional study of vertebral morphometry in 449 unscreened postmenopausal women, from the ages of 40 to 80, is reported. The wedge angles of thoracic vertebrae T4-12 were found to increase exponentially as a function of age, up to 70 years. In addition to age, the wedging phenomenon was found to be accentuated by increased bone turnover due to low calcium intake, reduced physical activity, each successive delivery, and breast feeding. Most of these variables were not correlated with isolated vertebral wedge angles, but rather with the sum of them (Sigma, sigma), assumed to assess the impact of those variables on thoracic kyphosis. In a subset of women, sigma was found to be inversely correlated with low spinal mineral density at L2-4. T-11 and T-12 were the vertebrae most frequently deformed (wedge angle exceeding mean +/- 3 SD in a group of 50 young healthy women, 25-45 years old). The distribution of deformed vertebrae was found to be significantly different from those qualified as "fractured" according to Kleerekoper et al.'s (1984) and Melton et al.'s (1989) criteria. The overall information afforded by past and present data indicates that in postmenopausal women, vertebral deformation may occur with the help of mechanical solicitations plus high bone remodeling rates, as well as by structural collapse (fracture). The information obtained does not allow one to quantify the relative contribution of each set of factors to the wedging phenomenon.

Adult↗
PubMed1993

Insulin sensitivity in familial hypercholesterolemia.

Insulin resistance is found in association with obesity, non-insulin-dependent diabetes mellitus, and essential hypertension, which are all risk factors for atherosclerotic cardiovascular disease. Furthermore, hyperinsulinemia has been reported in familial combined hyperlipoproteinemia and endogenous hypertriglyceridemia. Finally, relatively high serum triglyceride and low high-density lipoprotein (HDL) cholesterol concentrations invariably accompany hyperinsulinemia. Whether insulin sensitivity is affected by the isolated presence of high levels of serum low-density lipoprotein (LDL) cholesterol has not been clearly established. We studied 13 subjects with heterozygous familial hypercholesterolemia (FHC) and 15 normocholesterolemic subjects selected to be free of any other known cause of insulin resistance. Thus FHC patients and controls had normal body weight and fat distribution, glucose tolerance, blood pressure, and serum triglyceride and HDL cholesterol concentrations, but were completely separated on plasma LDL cholesterol concentrations (6.05 +/- 0.38 v 3.27 +/- 0.15 mmol/L, P < .0001). Fasting plasma levels of glucose, insulin, free fatty acids (FFA), and potassium and fasting rates of net carbohydrate and lipid oxidation were superimposable in the two study groups. During a 2-hour euglycemic (approximately 5 mmol/L) hyperinsulinemic (approximately 340 pmol/L) clamp, whole-body glucose disposal rates averaged 30.4 +/- 2.3 and 31.1 +/- 3.0 mumol.kg-1 x min-1 in FHC and control subjects, respectively (P = 0.88). The ability of exogenous hyperinsulinemia to stimulate carbohydrate oxidation and energy expenditure and suppress lipid oxidation and plasma FFA and potassium levels was equivalent in FHC and control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Effects of low-dose oral contraceptives on sugar metabolism].

The effects on carbohydrate metabolism by four low-dose oral contraceptives were evaluated in four low-dose oral contraceptives were evaluated-66 young women randomly divided in four groups. In the various preparations there were a different dosage of estrogen (ethinylestradiol) together different doses and types of progestogen (desogestrel, gestodene, cyproterone acetate). After six months of treatment, in all groups a slight increase of glycemic and insulinemic responses during OGTT was observed; the significance was achieved with the preparation containing cyproterone acetate alone. Glycated hemoglobin did not change. Our results suggest that these new low-dose oral contraceptives induced negligible metabolic side effects.

Adolescent↗
PubMed1988

Salivary immunoreactive insulin: a new entry in clinical chemistry?

The distribution of salivary immunoreactive insulin (S-IRI) and its relation to plasma insulin (P-IRI) and other clinical and metabolic variables were investigated in 93 nondiabetic subjects (60 males, 33 females, ages 11-70 y). S-IRI was measured by RIA, with monoiodinated insulin as labeled antigen and with standards consisting of serial dilutions in saliva of known amounts of native insulin. The sensitivity of the method was 12.1 pmol/L. The intra- and between-assay CVs were near 10%, and analytical recovery exceeded 93% for various insulin concentrations added to saliva. S-IRI, measured after overnight fast, showed a nonguassian distribution in males (skewness 1.18, kurtosis 1.41) and females (skewness 1.71, kurtosis 1.18); mean and median values were higher in males (14.3 and 12.1 nmol/min) than in females (12.1 and 7.15 nmol/min), but not significantly so. S-IRI was significantly correlated with P-IRI both in males (r = 0.75, P less than 0.0001) and females (r = 0.72, P less than 0.0001). These results, particularly the correlation between S-IRI and P-IRI, indicate the possibility of using S-IRI measurement in clinical practice.

Adolescent↗
PubMed1987

Inappropriate growth hormone response to luteinizing hormone-releasing hormone in diabetes mellitus.

We randomly administered luteinizing hormone-releasing hormone (LHRH) or thyrotropin releasing hormone (TRH) (25 micrograms and 200 micrograms, respectively, as a bolus), to 16 diabetic male subjects (9 type I, 7 type II) and to 9 healthy male controls in two different mornings. While GH in the basal state was similar in type I, type II, and normal subjects, LHRH administration surprisingly evoked a significant GH release in 7 (5 type 1, 2 type II) diabetic patients. GH-responders had higher glycated hemoglobin than non-responders (11 +/- 1 nu 8.3 +/- 0.5%) but superimposable fasting and intratest average glucose levels. Only one patient among the GH-responders to LHRH showed a GH release also after TRH. These data support the hypothesis that GH secretion in diabetes, especially when poorly controlled, is abnormal.

Blood Glucose↗
PubMed1987

The effects of starvation and sexual maturation on Na+ transbranchial fluxes following direct transfer from fresh water to sea-water in rainbow trout (Salmo gairdneri).

1. The perfused isolated head technique has been used to measure sodium arterial fluxes following direct transfer from fresh water to sea-water. 2. A starvation-related decrease in net sodium flux is reported. 3. Sexual maturation slackens the decrement of this net flux. 4. In starved fish, the cytological modifications of chloride cells following such a transfer are delayed. 5. This effect of starvation is discussed in terms of lamella sodium imperviousness.

Animals↗
PubMed1987

A sensitive high performance liquid chromatographic method for determining small amounts of glycosylproteins.

We developed a simple isocratic high performance liquid chromatography (HPLC) method for the quantitative determination of 5-hydroxymethyl-2-furfuraldehyde (5-HMF) liberated by mild hydrolysis of small amounts of glycosyl proteins. The absorbance of hydrolysate components after HPLC separation was recorded at 280 nm. To detect substances possibly interfering with the 5-HMF peak we always recorded the ratio of the peak heights A280 nm/A254 nm which was a constant value of 4.4. For each sample the blank was obtained by reduction with NaBH4 before hydrolysis with oxalic acid 1 mol/l. The best NaBH4/protein ratio was found to be 4 mg/mg. With this method we measured the nonenzymatic glycosylation (glycation) as 5-HMF in samples with a protein concentration as low as 0.8 mg/ml. 5-HMF produced per milligram of protein was independent from protein concentration for a wide range (0.8-10 mg/ml). The mean coefficient of variation for within assay and between precision was 6.8 and 11.6%, respectively. The 5-HMF measured on plasma proteins from normal subjects (n = 7) was 0.16 +/- 0.04 nmol/mg. Protein from insulin-dependent diabetic patients was 0.31 +/- 0.07 nmol/mg. With this method we succeeded in detecting an excessive glycation of platelet membrane proteins in 13 type-I diabetic patients.

Blood Platelets↗
PubMed1986

A14-[125I]monoiodoinsulin purified by different high-performance liquid chromatographic procedures and by polyacrylamide gel electrophoresis: preparation, immunochemical properties and receptor binding affinity.

Reversed-phase high-performance liquid chromatography (RP-HPLC) allows the rapid separation of A14-[125I]monoiodoinsulin directly from the iodination mixtures. It remains to be clarified, however, whether the RP-HPLC chromatographic conditions affect the properties of the purified tracer. In this study we prepared A14-[125I]insulin purified by polyacrylamide gel electrophoresis (PAGE) and by three different RP-HPLC mobile phases containing, respectively, ammonium acetate, sodium perchlorate and trifluoroacetic acid. The binding characteristics of all these tracers were examined using an insulin antiserum and insulin cell receptors. The specific radioactivity corresponded to the theoretical maximum for the RP-HPLC-purified tracers and was significantly lower for the PAGE-purified tracers. Significant differences were found in the binding of different tracers to the insulin antiserum: maximum binding ranged from 94 to 99% and was significantly lower for tracers purified by RP-HPLC eluents B and C; antiserum dilution giving 50% tracer binding was lower for tracers purified by RP-HPLC eluent B. The four insulin derivatives showed no difference in non-specific precipitation and in the affinity constant values calculated from the Scatchard analysis. No significant difference was found in the binding of the four insulin derivatives to the human-cultured IM-9 lymphocytes and to the human circulating monocytes. In conclusion, the present work demonstrates that the immunological properties of the A14-[125I]monoiodoinsulin purified by RP-HPLC may be partially affected by the composition of the mobile phase. In order to obtain a fully potent A14-[125I]insulin derivative and to have the possibility of comparing data from different laboratories, the chromatographic conditions must be taken into account.

Adult↗
PubMed1986

Salivary insulin concentrations in type 2 (non-insulin-dependent) diabetic patients and obese non-diabetic subjects: relationship to changes in plasma insulin levels after an oral glucose load.

The presence of immunoreactive insulin in saliva and its relationship to plasma immunoreactive insulin was investigated in healthy subjects, newly diagnosed non-obese Type 2 (non-insulin-dependent) diabetic patients and obese non-diabetic subjects, basally and after an oral glucose tolerance test. The mean +/- SEM fasting values of plasma and salivary immunoreactive insulin were significantly higher in diabetic patients and obese non-diabetic subjects than in normal volunteers (p less than 0.05). During the glucose challenge, the increase of salivary insulin was related with that of plasma in the three groups of subjects, with a time lag in normal and obese subjects. In normal volunteers, plasma and salivary peak values were respectively 49.5 +/- 13.4 microU/ml (p less than 0.05 vs obese subjects) at 60 min and 12.0 +/- 3.3 microU/min (p less than 0.05 vs obese subjects) at 120 min; in diabetic patients, the values were 51.7 +/- 5.6 microU/ml (p less than 0.05 vs obese subjects) and 14.6 +/- 4.1 microU/min at 120 min; in obese subjects, the peak value for plasma insulin was 111.5 +/- 40.1 microU/ml at 90 min and for salivary insulin 15.6 +/- 5.1 microU/min at 120 min. A positive linear relationship was shown between plasma and salivary insulin during the oral glucose tolerance test. The identity of salivary insulin was assessed by reversed-phase HPLC. We conclude that salivary immunoreactive insulin can be found in Type 2 diabetic patients and in obese non-diabetic subjects, as well as normal volunteers, that plasma and salivary insulin are related after a glucose load, and that differences exist in salivary insulin secretion patterns among the three groups of subjects.

Adult↗
PubMed1986

Effects of autonomic blockade on dual atrioventricular nodal pathways pattern.

Fifteen patients (age: 57.6 +/- 14 years) showing dual A-V nodal pathways pattern during basal electrophysiological testing were studied following pharmacological autonomic blockade (iv propranolol 0.2 mg/Kg and iv atropine 0.04 mg/Kg). After induction of the autonomic blockade, the dual A-V nodal pathways pattern was not present in four patients due to disappearance of the slow pathway; the pattern remained in 11 (73%). The longest A2-H2 interval, the effective and functional refractory periods of the fast pathway did not change significantly following autonomic blockade. Even the electrophysiological measures of the slow pathway, in the 11 patients in whom they were comparable, did not change significantly after autonomic blockade. These data suggest that: the dual A-V nodal pathways pattern is mainly related to the intrinsic structure of the A-V node; the autonomic nervous system only affects in a variable way the refractoriness and the conduction velocity in the two pathways.

Adult↗
PubMed1985

A method for evaluating different modes of action of an antiarrhythmic drug in man. The effects of propafenone on sinus nodal functions.

In vitro experiments have shown that the antiarrhythmic effects of propafenone are due to a direct depressant action and to a beta-blocking activity. In this study a method was used to evaluate the direct effect and the autonomically mediated actions of an antiarrhythmic agent in a clinical setting. An electrophysiological study was performed twice, at an interval of 24 hr, in 17 patients (age: 52 +/- 17 years) with normal resting and intrinsic heart rate. In the first study the overall effect of intravenous propafenone (1.5-2 mg/kg) was evaluated by comparing the sinus node parameters obtained during the basal state and after drug administration. In the second study the direct depressant effect of the drug was evaluated by comparing the electrophysiological variables obtained following autonomic blockade (propranolol 0.2 mg/kg and atropine 0.04 mg/kg) and after propafenone. In the first study there was no significant change in the sinus cycle length and corrected sinus node recovery time and only a small (9.1%) increase in sinuatrial conduction time, whereas in the second study these variables increased significantly. The degree of increase in sinus cycle length and corrected sinus node recovery time was significantly higher in the second study than in the first one. These data suggest that: (1) propafenone has direct depressant effect on sinus automaticity but this effect is counteracted by autonomically mediated actions (most likely of vagolytic type); (2) the beta-blocking effect of the drug demonstrated in isolated atria is not seen in a clinical setting.

Adolescent↗
PubMed1985

Electrophysiology of normal anterograde atrio-ventricular conduction with and without autonomic blockade.

The electrophysiological measures of atrio-ventricular (A-V) conduction were investigated in 20 normal subjects (mean age: 43.9 +/- 15.7 years) both during basal state and after pharmacological autonomic blockade. In the basal state A-H and H-V intervals and H wave duration ranged from 55-110 ms (mean 83 +/- 15.9), 35-45 ms (mean 39.5 +/- 3.9) and 10-20 ms (mean 17 +/- 4.1), respectively. The lowest atrial rate inducing Wenckebach periods ranged from 150-200 beats min-1 (mean 176.5 +/- 13.8). The effective refractory period (ERP) and the functional refractory period from FRP) of the atrium ranged from 160-260 ms (mean 211 +/- 26.7) and 210-280 ms (mean 252.5 +/- 21.2), respectively. The ERP and the FRP of the A-V node were in the ranges 230-310 ms (mean 269.3 +/- 27.2) and 330-450 ms (mean 395 +/- 41.2), respectively. After autonomic blockade the H-V interval and the H wave duration did not change in any subject. The A-H interval was in the range 55-105 ms (mean 82.5 +/- 15) and the lowest atrial rate inducing Wenckebach periods 150-220 beats min-1 (mean 179.5 +/- 13.5). The ERP and the FRP of the atrium ranged from 170-270 ms (mean 215.5 +/- 28.3) and 210-300 ms (mean 254 +/- 27.2), respectively. The ERP and the FRP of the A-V node were in the ranges 220-320 ms (mean 260.8 +/- 32) and 330-440 ms (mean 383.3 +/- 43.7), respectively. The A-V node variables did not change significantly following autonomic blockade. These data indicate that: the definition of normal values of A-V node measurements after autonomic blockade allow us to evaluate the role of the autonomic nervous system in the patients with A-V node conduction disturbances; in the basal state the normal values of A-V conduction variables we obtained, of refractory periods in particular, are shorter than those previously reported; this appears to be related to the strict criteria we used in subject selection.

Adolescent↗
PubMed1985

[Effects of the autonomic nervous system on the refractory periods of atrioventricular conduction in man].

The purpose of the work is to evaluate in clinical setting the effects of autonomic nervous system on the refractory periods of atrio-ventricular (A-V) conduction. Electrophysiological study was carried out, both during basal state and after autonomic blockade induced by i.v. administration of propranolol 0.2 mg/Kg and atropine 0.04 mg/Kg, in 21 subjects with normal atrio-ventricular node conduction (A-H less than or equal to 120 msec) and normal sinus rate (mean age: 54.3 +/- 16.3 years). Following autonomic blockade the sinus cycle length decreased significantly (P less than 0.01), whereas A-H interval, A1-H1 interval at cycle length of 460 msec and the longest atrial pacing cycle length inducing Wenckebach block did not change significantly. Effective and functional refractory periods of the A-V node did not show significant variations after autonomic blockade (342.2 +/- 41 versus 337.2 +/- 54.2 msec and 435.9 +/- 58.9 versus 430 +/- 60.9 msec, respectively); however, these refractory periods changed variably from subject to subject; in some patients they increased and in others there was a marked decrease. There were no significant variations of atrial effective and functional refractory periods after autonomic blockade (249.5 +/- 29.6 versus 256.6 +/- 31.9 msec and 276.4 +/- 27.1 versus 287.7 +/- 33.4 msec, respectively); they too showed a variable response from subject to subject. The relative refractory period of His-Purkinje system, evaluated in 3 patients, increased in all after autonomic blockade (420 +/- 20 versus 463.3 +/- 15.2 msec).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗