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Biomedical subjects

O Carandente

Publications and source records attributed to O Carandente.

At least 19 recordsLinked to original sources
PubMed2002

Autoantibodies to amphiphysin I and amphiphysin II in a patient with sensory-motor neuropathy.

A proportion of patients with peripheral neuropathies has circulating autoantibodies directed against neural antigens. In some cases, autoantibodies may play a pathogenic role. We studied a patient with a progressive sensory-motor axonal neuropathy of unknown etiology, looking for circulating autoantibodies against neural antigens and we showed that the patient's serum contained anti-amphiphysin I (AMP I) and amphiphysin II (AMP II) autoantibodies. A sural nerve biopsy revealed an axonal neuropathy. Indirect immunofluorescence experiments with the patient's serum showed a staining of rat axons due to alpha-AMP I autoantibodies and a specific labelling of cytoplasm and Schmidt-Lanterman incisures of Schwann cells due to alpha-AMP II autoantibodies. In conclusion we identified a patient affected by a sensory-motor neuropathy with autoantibodies against both AMP I and AMP II.

Aged↗
PubMed2001

High glucose causes apoptosis in cultured human pancreatic islets of Langerhans: a potential role for regulation of specific Bcl family genes toward an apoptotic cell death program.

Type 2 diabetes is characterized by insulin resistance and inadequate insulin secretion. In the advanced stages of the disease, beta-cell dysfunction worsens and insulin therapy may be necessary to achieve satisfactory metabolic control. Studies in autopsies found decreased beta-cell mass in pancreas of people with type 2 diabetes. Apoptosis, a constitutive program of cell death modulated by the Bcl family genes, has been implicated in loss of beta-cells in animal models of type 2 diabetes. In this study, we compared the effect of 5 days' culture in high glucose concentration (16.7 mmol/l) versus normal glucose levels (5.5 mmol/l) or hyperosmolar control (mannitol 11 mmol/l plus glucose 5 mmol/l) on the survival of human pancreatic islets. Apoptosis, analyzed by flow cytometry and electron and immunofluorescence microscopy, was increased in islets cultured in high glucose (HG5) as compared with normal glucose (NG5) or hyperosmolar control (NG5+MAN5). We also analyzed by reverse transcriptase-polymerase chain reaction and Western blotting the expression of the Bcl family genes in human islets cultured in normal glucose or high glucose. The antiapoptotic gene Bcl-2 was unaffected by glucose change, whereas Bcl-xl was reduced upon treatment with HG5. On the other hand, proapoptotic genes Bad, Bid, and Bik were overexpressed in the islets maintained in HG5. To define the pancreatic localization of Bcl proteins, we performed confocal immunofluorescence analysis on human pancreas. Bad and Bid were specifically expressed in beta-cells, and Bid was also expressed, although at low levels, in the exocrine pancreas. Bik and Bcl-xl were expressed in other endocrine islet cells as well as in the exocrine pancreas. These data suggest that in human islets, high glucose may modulate the balance of proapoptotic and antiapoptotic Bcl proteins toward apoptosis, thus favoring beta-cell death.

Apoptosis↗
PubMed1999

Crosstalk between insulin and angiotensin II signalling systems.

Insulin resistance and hypertension commonly occur together. Pharmacological inhibition of the renin-angiotensin system has been found to reduce not only hypertension, but also insulin resistance. This raises the possibility that the renin-angiotensin system may interact with insulin signalling. We have investigated the relationship between insulin and angiotensin II (AII) intracellular signalling in vivo using an intact rat heart model, and in vitro using rat aorta smooth muscle cells (RASMC). Results generated in the in vivo studies indicate that, like insulin, AII stimulates tyrosine phosphorylation of the insulin receptor substrates IRS-1 and IRS-2. This leads to binding of IRS-1 and IRS-2 to PI3-kinase. However, in contrast to the effect of insulin. IRS-1- and IRS-2-associated PI3-kinase activity is inhibited by AII in a dose-dependent manner. Moreover, AII inhibits insulin-stimulated IRS-1/IRS-2-associated PI3-kinase activity. The in vivo effects of AII are mediated via the AT1 receptor. The results of the in vitro studies indicate that AII inhibits insulin-stimulated, IRS-1-associated PI3-kinase activity by interfering with the docking of IRS-1 with the p85 regulatory subunit of PI3-kinase. It appears that AII achieves this effect by stimulating serine phosphorylation of the insulin receptor beta-subunit IRS-1, and the p85 regulatory subunit of PI3-kinase. These actions result in the inhibition of normal interactions between the insulin signalling pathway components. Thus, we believe that AII negatively modulates insulin signalling by stimulating multiple serine phosphorylation events in the early components of the insulin signalling cascade. Overactivity of the renin-angiotensin system is likely to impair insulin signalling and contribute to insulin resistance observed in essential hypertension.

Angiotensin II↗
PubMed1997

Impaired left ventricular filling dynamics in patients with angina and angiographically normal coronary arteries: effect of beta adrenergic blockade.

OBJECTIVE: To assess exercise performance and resting left ventricular filling dynamics in patients with syndrome X (SX) in basal conditions and after 10 days treatment with oral atenolol. DESIGN AND PATIENTS: Exercise performance was studied and left ventricular filling assessed by Doppler-derived transmitral flow pattern analysis in 22 patients (16 female, mean (SD) age 53 (4) years) with angina, a positive exercise test, and angiographically smooth coronary arteries. Patients were studied after two 10 day treatment periods with either atenolol or placebo in a single-blind, randomised, crossover trial. The same protocol was followed in 10 patients with documented coronary artery disease (CAD) and in 13 controls (C). RESULTS: Unlike the controls, patients with SX and those with CAD consistently showed exercise-induced ST segment abnormalities and impaired resting left ventricular filling while on placebo. Atenolol significantly reduced episodes of angina, completely prevented exercise-induced ST segment changes in 18 SX patients, and delayed their onset in all patients with CAD: in both groups the agent significantly improved Doppler-derived indices (mean (SD)) of ventricular filling (E/A 0.97 (0.27) v 1.22 (0.32) and 0.84 (0.21) v 1.19 (0.37), respectively). CONCLUSIONS: The objective documentation of left ventricular filling abnormalities may be useful in confirming the clinical diagnosis of SX and in providing objective evidence of therapeutic benefit. The similarity of the symptoms and electrocardiographic and ventricular filling abnormalities found in patients with SX and in those with CAD suggests that ischaemia is involved in both groups.

Adrenergic beta-Antagonists↗
PubMed1996

Thrombolytic therapy reduces the incidence of left ventricular thrombus after anterior myocardial infarction. Relationship to vessel patency and infarct size.

BACKGROUND: Controversial evidence exists as to whether thrombolytic therapy reduces the incidence of left ventricular thrombus in acute myocardial infarction and, if so, how this relates to successful reperfusion. METHODS: Four hundred and eighteen consecutive patients underwent echocardiography and coronary angiography within 3 weeks of an acute myocardial infarction. A dyssynergic score was calculated by analysing regional wall motion in 18 left ventricular segments. The infarct-related artery was considered patent if TIMI grade 2 or 3 flow and less than 90% stenosis were present. Retrograde perfusion by Rentrop's grade 2 or 3 collaterals was considered significant. RESULTS: Large anterior myocardial infarctions were associated with the highest prevalence (39%) of left ventricular thrombosis. Thrombus was also very frequent if the left anterior descending coronary artery was occluded and no collaterals to the infarct area were seen (75%). Anticoagulant therapy reduced the prevalence of left ventricular thrombus, regardless of whether the infarct-related vessel was patent or not. Conversely, in patients undergoing thrombolysis the incidence of left ventricular thrombosis was lower when the left anterior descending coronary artery was patent, and especially when an early creatine kinase peak, suggestive of reperfusion, was recorded (7%). Finally, the presence of left ventricular thrombosis was inversely related to the asynergy score. CONCLUSION: These observations suggest that the presence of left ventricular thrombus is related to the extent of myocardial damage. Thrombolytic therapy reduces thrombus probably by salvaging myocardium at risk.

Adult↗
PubMed1992

Coronary collaterals reduce the duration of exercise-induced ischemia by allowing a faster recovery.

The role of collaterals in influencing postischemic recovery after exercise testing has not been investigated previously. We studied 54 patients (mean age 59 +/- 6 years) with effort-induced angina and documented coronary disease who underwent exercise testing and thallium-201 myocardial scintigraphy. On angiography, 30 patients (group A) exhibited visible collaterals (grade 2 to 3, Cohen and Rentrop classification) perfusing the ischemic zone, whereas the other 24 (group B) did not. Patients with collaterals had more severe coronary artery disease (Gensini score 46.9 +/- 16 vs 28.6 +/- 18; p less than 0.001) and more severe impairment of coronary flow reserve (time and rate-pressure product to 1 mm ST segment depression 3.5 +/- 0.8 vs 4.8 +/- 0.6 minutes, p less than 0.01; 14,189 +/- 2451 vs 16,081 +/- 2215 beats/min x mm Hg, p less than 0.04, respectively). However, in these patients the ECG returned to baseline more rapidly after exercise (5.5 +/- 1.6 vs 11.7 +/- 3.3 minutes; p less than 0.001). Therefore, although collaterals do not apparently prevent or delay the development of exercise-induced ischemia, they can limit its duration by allowing a faster recovery.

Angina Pectoris↗
PubMed1992

[An analysis of the variability in the heart rate in relation to the presence of transient ischemia and to its physiopathological mechanism].

To assess the differences in the pathogenesis of cardiac ischemic events and the role of the autonomic nervous system, we studied the electrocardiographic measures of tonic vagal activity during 24-hour Holter monitoring. We tested the circadian rhythm of the power in the high frequency energy (HF: 0.15-0.40 Hz) of the normal R-R interval power spectrum, the daily percent of successive normal R-R greater than 50 ms (pNN50) and the roots mean square of successive difference of normal R-R intervals (MMSD) in patients with coronary artery disease of comparable angiographic severity. Group A consisted of 5 patients (mean age 62 +/- 8) with chronic stable angina and Group B of 5 patients (mean age 61 +/- 8) with variant angina. Characteristic anginal pattern, typical ST changes during ischemic events on Holter monitoring and angiographic evidence of vasoconstriction induced by hyperventilation distinguished the 2 groups. Mean Cosinor analysis showed the presence of a significant circadian rhythm of HF only in Group A with a peak in the early morning hours (phi at 03.45, % rhythm 50.0, p less than 0.03); a significant reduction of parasympathetic activation was also found in Group B (MSSD: 27.8 vs 15.4, p less than 0.05; pNN50: 2.9 vs 0.6, p less than 0.05). These results suggest a different pattern in circadian variation of HF and lower degree of time and frequency domain of heart rate variability, as a marker of vagal tone in patients with high susceptibility to coronary vasospasm.

Angina Pectoris, Variant↗
PubMed1990

[Sodium nitroprusside and inhibition of coronary vasoconstriction in isolated hearts of guinea pigs].

Recent data suggest that nitrate compounds, beside determining vasodilatation by cGMP-mediated Ca++ uptake in the sarcoplasmic reticulum, may also inhibit vasoconstriction by reducing phosphatidyl inositol bisphosphate hydrolysis, a major step in the biochemical pathway responsible for vasoconstriction induced by a variety of agents including angiotensin II (AII). We assessed the inhibitory effects of Na-nitroprusside (NP) on the coronary resistances induced by increasing doses of AII in Krebs perfused (basal pressure: 2.5-3 KPa) Guinea-pig isolated hearts. AII bolus injections (5 to 100 ng) were given before and 10 min after a 7.6.10(-8) to 7.6.10(-6) M infusion of NP for 10 min. AII produced a highly reproducible, linearly dose-related, increase in perfusion pressure (PP) (5 ng: 4.4 +/- 1.16; 10 ng: 8.1 +/- 2.1; 25 ng: 18.7 +/- 3.06; 50 ng: 23.6 +/- 2.31; 100 ng: 30 +/- 1.37 mmHg) that was persistently and dose-dependently inhibited by NP. Well after (greater than 10 min) full recovery from the initial NP-induced vasodilatation and drop in PP its inhibitory effect was observed, varying from 22.1% at the maximal AII and minimal NP does and 90.6% at the minimal AII and maximal NP doses. This study demonstrates that, apart from causing the well-known immediate vasodilatory response by stimulation of cGMP synthesis, NP also causes delayed inhibition of AII-induced coronary vasoconstriction, possibly by preventing phosphatidyl inositol hydrolysis.

Angiotensin II↗
PubMed1988

Erythrocyte D-glucose transport activity in reconstituted model membranes of different lipid composition.

The stereospecific influx of D-glucose into liposomes formed on sonication of different glyco- and phospholipids with transport proteins from human erythrocyte ghosts solubilized with Triton x-100 was measured as an index of their total D-glucose transport activity. Specific D-glucose transport increased when acidic phospho- and glycolipids (especially sulfatide) were added to the phosphatidylcholine bilayers of the model membranes while cholesterol strongly inhibited the process. The modulation of D-glucose transport activity and its possible correlation with the lipid composition and the chemico-physical state of the erythrocytes is discussed.

Cerebrosides↗
PubMed1987

Two circadian rhythms and an infradian rhythm in human cardiac arrhythmia?

Circadian and infradian rhythmometry can and should be applied for the "isolation" of components in a broad spectrum of rhythms with different frequencies that can characterize the occurrence, among other pathologies, of ischemia in the electrocardiogram (ECG). Analyses of data from the literature on the recurrence of cardiac ischemia in a 12-day electrocardiographic record show two phase-drifting, internally and externally desynchronized, circadian rhythmic components and an infradian about-half-weekly modulation. ECGs covering spans much longer than 12 days are indicated in order to distinguish transient phase-drifts from long-maintained desynchronization. To assess the importance of such phenomena for diagnosis, prognosis, and treatment, a recording with accompanying as-one-goes analyses of data is indicated.

Arrhythmias, Cardiac↗
PubMed1985

[ Methodological evaluation and clinical significance of erythrocyte aggregation].

Red cell aggregation, which occurs in vivo when blood flow slows down, has been studied in 22 healthy subjects and 31 type I diabetics by means of Myrenne MA1 automatic aggregometer. First of all, the most reliable and precise technique has been studied: the best results have been obtained employing 25 microliters of K2-EDTA-anticoagulated blood stored between 0 and 20 degrees C for a maximum of 4 h. The present study has shown statistically significant differences (p = 0.01) between the two groups studied (controls: mean = 11.895 MEA +/- 0.863; diabetics: mean = 15.552 MEA +/- 0.985). Moreover, correlations between erythrocyte aggregability and hematochemical and rheological parameters like fibrinogen, ESR, serum proteins, plasma and blood viscosity, have been evaluated.

Blood Flow Velocity↗
PubMed1985

[Changes in hemorheological parameters during physical exertion in coronary disease patients].

Blood viscosity and filtrability have been studied in 7 patients with ischemic heart disease and in 9 control subjects before and after maximal stress test on cycloergometer. The diagnosis of ischemic heart disease has been previously established on the basis of the clinical history, abnormal stress test or coronary arteriography. No significant differences were observed, at rest, in the two groups. On the contrary, after stress test blood filtrability resulted significantly reduced in ischemic patients when compared to controls. Blood viscosity resulted substantially unchanged in both groups. Our data may suggest the existence of an alteration in blood filtrability during stress test with a possible pathogenetic role.

Blood Viscosity↗
PubMed1985

[Effect of hemorheology in the post-operative period].

Very important hemorheological changes characterize the early post-operative period. This research, performed on a group of 10 patients who underwent aorto-ilio-femoral revascularization, enables us to observe that these changes are present also in vascular surgery. In fact, plasma fibrinogen, red cells aggregation and deformability, whole blood viscosity, already modified in the pre-operative period in patients with peripheral arteriopathy, resulted significantly impaired on the 2nd and 6th day after the operation. Such changes must be considered in order to avoid ischemic consequences on microcirculation, the possible onset of deep vein thrombosis as well as an impairment of the prognosis of vascular operations (early and late reobliteration), and in order to perform an adequate and prophylactic corrective treatment.

Adult↗
PubMed1984

Studies of the clinical pharmacology and therapeutic efficacy of pentoxifylline in peripheral obstructive arterial disease.

Studies were carried out to investigate the effects of pentoxifylline on various hemorheological (whole blood, plasma and serum viscosity, erythrocyte filtrability, hematocrit), hemostasiological (blood coagulation and fibrinolysis: euglobulin lysis time, fibrinogen, plasminogen, alpha-2-macroglobulin, alpha-1-antitrypsin, antiplasmin; platelet function: beta-thromboglobulin), and hemodynamic factors (limb perfusion: rest and peak flow, time to peak flow; systemic blood pressure, heart rate). In addition, clinical efficacy was monitored in patients with claudication by assessing walking capacity under placebo controlled double blind cross over conditions. The investigations disclosed the positive influence of acute and chronic pentoxifylline administration on hemorheological, hemostasiological and perfusion parameters, most of the changes recorded being statistically significant. The clinical benefit of pentoxifylline (Trental 400) treatment was demonstrated by the significantly superior increase in walking capacity in comparison to placebo in the controlled study.

Alprostadil↗
PubMed1983

A quantitative electron microscope study of the perikaryal projections of sensory ganglion neurons. I. Cat and rabbit.

With a quantitative method and serial sections a study was carried out under the electron microscope of the perikaryal projections of the neurons in the thoracic spinal ganglia of cat and rabbit. These projections usually appear as finger-shaped evaginations which run roughly parallel to the surface of the nerve cell body. Their length ranges between 0.3 and 3.25 microns, and they show a nearly circular cross section with a rather uniform transverse diameter having an average value of about 0.2 microns. Both in cat and rabbit a very high correlation was found between the surface area of perikaryal projections and both the volume and smoothed surface area of the corresponding nerve cell body. Perikaryal projections increase the surface area of the nerve cell body by 43% in cat and 39.5% in rabbit. These findings support the idea that perikaryal projections in sensory ganglion neurons are normal formations, which maintain the surface-to-volume ratio above the critical level for metabolic exchanges.

Animals↗