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Biomedical subjects

A De Micheli

Publications and source records attributed to A De Micheli.

At least 19 recordsLinked to original sources
PubMed1992

Impaired myogenic responsiveness of renal microvessels in Dahl salt-sensitive rats.

The mechanisms mediating abnormal renal autoregulation in Dahl salt-sensitive (DS) rats have not been fully defined. In the present study, we assessed myogenic responsiveness of interlobular arteries (ILAs), afferent arterioles (AAs), and efferent arterioles in isolated perfused hydronephrotic Dahl rat kidneys. Dahl rats were divided into four groups according to strain (Dahl salt-resistant [DR] or DS rats) and dietary sodium manipulation (rats fed low or high salt diets). Systolic blood pressure was elevated only in DS rats fed the high salt diet (202 +/- 4 mm Hg, p less than 0.05). Myogenic responses were obtained by stepwise elevation of renal arterial pressure. Vessel diameters were determined by computer-assisted videomicroscopy. Preglomerular microvessels of DS and DR rats responded differently to changes in renal arterial pressure. AAs and ILAs manifested diminished myogenic responsiveness to increasing renal arterial pressure in DS rats compared with DR rats (p less than 0.05). Both AAs and ILAs in DS rats manifested a higher threshold pressure for eliciting myogenic responses and a decrease in maximal pressure-induced vasoconstriction. The sensitivity of the AA myogenic response to nifedipine was enhanced in DS rats compared with DR rats (p less than 0.05). For rats fed the high salt diet, preglomerular vessels exhibited reduced myogenic responsiveness in both strains. In contrast to preglomerular microvessels, efferent arterioles from all four groups of rats failed to exhibit pressure-induced vasoconstriction. Our data suggest that diminished myogenic responsiveness of AAs and ILAs in DS rats contributes to impaired renal autoregulation in this strain.

Animals↗
PubMed1979

[Insulin response and NEFA behavior in volunteers with a flat response to oral glucose tolerance test].

The insulin response and the NEFA behaviour of 7 lean and 8 obese subjects with a flat response to an oral glucose tolerance test have been studied. A flat response has been defined as one in which the maximum glycemic increase and the area of increase does not exceed 32 mg% and 18 mg% respectively. The insulin response and the NEFA behaviour were similar both in lean and in obese subjects to controls with normal O.G.T.T. The glucose/I.R.I. ratios were increased. A possible physiopathological interpretation is proposed.

Adolescent↗
PubMed1979

[Special aspects of the curve of the oral glucose tolerance test].

The insulin response of 10 lean and 23 obese subjects with lag-type and borderline O.G.T.T. has been studied. The O.G.T.T. was interpreted according to the criteria of Fajans and Conn. The maximum increase and the area of increase were examined both for blood glucose and plasma I.R.I., and the corresponding I.R.I./glucose ratios calculated. The shape of the insulin response curve is similar to that of glucose curve. The I.R.I./glucose ratios are decreased in the lag-type curves as compared to borderline in the lean subjects while we observed opposite results in obese ones. A possible physiopathological interpretation of this curves is proposed.

Adolescent↗
PubMed1979

[Examination of the early phase of insulin secretion with 3 successive small overloads of glucose (5 g) in normal and obese subjects].

We studied the E.I.R. in eight normal subjects and fifteen obese ones with three successive small glucose pulses (5 g.) e.v. at 30' interval. In normal subjects the three successive loads gave rise to identical responses for both glucose and I.R.I. Obese could be divided, on the basis of their E.I.R. to the first load, into normal responders (group I), hyper-responders (group II) and hypo-résponders (group III); on the basis of the E.I.R. to the second load, group I could be divided in two subgroups: Ia and Ib. We found an identical E.I.R. to all glucose loads in group Ia; a reduced E.I.R. to successive loads in groups Ib and II. Group III didn't have any insulin response to all glucose loads.

Antigens↗
PubMed1979

[Double test of insulin sensitivity in normal and obese subjects].

13 normal and 16 obese subjects have been chosen for a double insulin tolerance test: 0,02 U/Kg of insulin were administered i.v. with an interval of 60'. The glycemic curve of the normal subjects show an identical lay out after both pulses; on the contrary the obese subjects could be divided into two subgroups. In the first one the lowering glucose action can be compared after both pulses, while in the second one the first stimulus causes a weather lowering glucose action, than in the first group, which is furtherly reduced during the subsequent pulse. An insulin resistance in these subjects is thus stressed. In the obese subjects the NEFA have a higher concentration in both groups than in the normal ones, show a normal decrease, but a certain delay is observed in the rebound phase.

Blood Glucose↗
PubMed1975

Experimental bases for diagnosis of left bifascicular and trifascicular block.

It seems to be justified to establish the diagnosis of fascicular blocks, in clinical tracings, on the basis of experimental findings. For this, we produced left bifascicular block as well as trifascicular block in the heart of 20 mongrel dogs. Because of left bifascicular block, the activation process is unequally delayed in high lateral and in posterior aspects of the free left ventricular wall. Nevertheless, it begins at normal time in middle left septal mass via intermediate strands of the left bundle. Consequently, left bifascicular block which resembles intermediate degree left truncular block, is recognizable by unequally delayed onset of intrinsicoid deflection in aVL, aVF and V6 and often by the manifestation of the first septal vector. Vectorcardiographic curves are diphasic and show initial and terminal slurrings. Trifascicular block delays the activation process in both ventricles. For this, the asynchronism between the electromotive forces of ventricles is lessened. The said conduction disturbance can be diagnosed by electrocardiographic and vectorcardiographic features suggesting intermediate degree RBBB as well as left bifascicular block.

Adult↗
PubMedDate not supplied

Exploration of the early insulin response by two small successive loads of I.V. glucose in normal and obese subjects.

Two 5 g glucose loads at 1-h interval were given to healthy controls and obese subjects with slightly altered or normal OGTT in order to explore the capacity of restoration of the "rapid insulin response" to i.v. glucose. In the normal subjects, the two successive loads gave rise to identical responses as far as maximum increase (delta max), average increase at 2-5 min (delta 2-5 min), area of increase 0-15 min (delta 0-15 min) for both glucose and IRI, were concerned. Obese subjects could be divided on the basis of their insulin response to the first load into normal responders (group I) and high-responders (group II). In group I obese subjects, the responses to the second load were identical to those to the first. In group II obese subjects delta max, delta 2-5 min and delta 0-15 min of the insulin response to the second load were reduced as compared to the first.

Adult↗
PubMedDate not supplied

I.V. glucose tolerance test: correlation between FFA, glucose and IRI in normal, obese and diabetic subjects.

Insulin response and FFA behavior have been evaluated during an IVGTT in 63 subjects of whom 18 were normal, 31 were obese (with varying degrees of carbohydrate tolerance) and 14 were mild non insulin-dependent diabetics. The extreme reduction of insulin secretion in the early phase (delta 0-15 min) and the less severe impairment of the late phase (delta 15-60 min) have been confirmed; obese subjects showed on the average an active insulin response to venous loading; this was more marked and more consistent in the late phase. Compared to controls, FFA concentration both in basal conditions and during IVGTT was progressively higher in obese and diabetic patients. When analyzing the interplay between IRI, KG and FFA in the course of IVGTT, it was observed that: (1) a close correlation exists between IG and early insulin response (r = 0.72); (2) a correlation between delta IRI 0-15 min and percentage decrease of FFA at 45 min is found only in normal subjects; (3) a negative highly significant correlation is found between KG and mean FFA plasma level 0-60 min. This last correlation is evidence of the important role played by FFA in carbohydrate tolerance. The conflicting results reported by others have been discussed.

Adult↗
PubMedDate not supplied

[Vectorcardiographic findings in atrial enlargement].

Rational interpretation of changes of the P loop, due to atrial enlargements, must be based on the magnitude and spatial orientation of the main resulting vectors of the atrial activation phenomenon. Under normal conditions, these ones give origin to a mean vector oriented to the left, downward and slightly forward. Right atrial enlargement can be recognized by P loops of more than 100 mcv. The main axis of the elongated PF is comprised between + 60 degrees and + 90 degrees; that of the open PH between + 70 degrees and + 80 degrees and that of PS is located around + 135 degrees. Left atrial enlargement can be diagnosed by a characteristic box glove configuration of the PF loop as well as by an eight-shaped PH. In some cases, the PS loop also becomes eight-shaped. Biatrial enlargement gives rise to slurrings and notchings of the distal portion of the PF loop, a diphasic aspect and frequently an eight-shaped configuration of the PH loop and a triangular morphology of PS, whose base lasts 30 msec. or more.

Cardiomegaly↗