PubMed Health⌕ Search

Biomedical subjects

G Gambassi

Publications and source records attributed to G Gambassi.

At least 109 records · Page 6Linked to original sources
PubMed1991

Ca2+ dependence of alpha-adrenergic effects on the contractile properties and Ca2+ homeostasis of cardiac myocytes.

alpha-Adrenergic stimulation is known to enhance myocardial contractility. Adult rat left ventricular myocytes bathed in 1 mM [Ca2+] (Ca0) and electrically stimulated at 0.2 Hz responded to alpha-adrenergic stimulation with 50 microM phenylephrine and 1 microM propranolol with an increase in twitch amplitude to 177.1 +/- 25.6% of control (mean +/- SEM). In contrast, when cell Ca2+ loading was increased by bathing cells in 5 mM Ca0, alpha-adrenergic stimulation decreased twitch amplitude to 68.6 +/- 8.2% of control. Time-averaged cytosolic [Ca2+] of cells in 1.0 mM Ca0 is enhanced via an increase in the frequency of electrical stimulation. When myocytes were stimulated at 2 Hz in 1 mM Ca0, alpha-adrenergic stimulation did not increase twitch amplitude (103.8 +/- 12.4% of control). In myocytes loaded with the Ca2+ probe into-1, alpha-adrenergic effects during stimulation at 0.2 Hz (an increase in twitch amplitude in 1 mM Ca0 and a decrease in twitch amplitude in 5 mM Ca0) were associated with similar changes in the indo-1 transient. In 5 mM Ca0, spontaneous Ca2+ releases from the sarcoplasmic reticulum (SR) occurred in the diastolic interval between twitches (2.9 +/- 1.4 spontaneous SR Ca2+ oscillations/min; n = 7); alpha-adrenergic stimulation abolished these oscillations in six of seven cells. Thus, an increase in the frequency of spontaneous diastolic SR Ca2+ release (i.e., Ca2+ overload) is not the mechanism for the negative inotropic effect of alpha-adrenergic stimulation in 5 mM Ca0. In experiments with unstimulated myocytes, we determined whether the effect of alpha-adrenergic stimulation on cell Ca2+ homeostasis and oscillatory SR Ca2+ release observed in 5 mM Ca0 occurs only during electrical stimulation, when voltage-dependent currents are operative, or also at rest. Unstimulated rat ventricular myocytes in 5 mM Cao exhibit oscillatory SR Ca2+ release; alpha-adrenergic stimulation decreased the frequency of these oscillations to 53.9 +/- 8.9% of control, and this effect was blocked by 1 microM prazosin. In unstimulated indo-1-loaded myocytes alpha-adrenergic stimulation decreased the resting indo-1 fluorescence ratio in 5 mM Ca0, whereas it had no effect in 1 mM Ca0. Additional experiments were aimed at defining a role for Ca(2+)-activated, phospholipid-dependent protein kinase C (PKC) for the negative inotropic effect of alpha-adrenergic stimulation in 5 mM Ca0. Short-term preexposure to 0.1 microM 4 beta-phrobol 12-myristate 13-acetate (PMA) has been shown to maximally activate PKC.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

[Alpha but not beta-adrenergic stimulation has a positive inotropic effect associated with alkalinization of intracellular pH].

There is increasing evidence that alpha-adrenoceptors also exist in the myocardium and that an increase in force of contraction may be produced by stimulation of these sites. This positive inotropism seems to be dependent either on an increased amount of Ca++ released into the cytosol with each action potential or on increased myofilament responsiveness. In contrast, beta-adrenergic stimulation reduces the sensitivity of the contractile proteins and the positive inotropic effect is due to the activation of L-type calcium channels on the sarcolemma. We used single, isolated, enzymatically dissociated, adult rat ventricular myocytes. Cells were loaded either with the ester derivative of the Ca++ probe Indo-1 or with the intracellular pH probe Snarf-1 and at the same time we measured the contractile parameters and monitored the fluorescence as an index of intracellular calcium concentration or pH value. The single cells (bicarbonate buffer continuously gassed with O2 95%, CO2 5%, Ca++ 1.5 mM, field stimulation 0.5 Hz) were exposed to phenylephrine (50 microM) and nadolol (1 microM). Alpha-adrenergic stimulation increased twitch amplitude (delta ES = 1.93 +/- 0.77, n = 8; p less than 0.05) and showed only a slight increase in Ca++ transient. On the other end, the positive inotropic effect (delta ES = 2.84 +/- 0.86, n = 4; p less than 0.02) obtained with beta-adrenergic stimulation (isoproterenol 50 nM, bicarbonate buffer, Ca++ 0.5 mM, field stimulation 0.2 Hz) was always associated with a large increase in intracellular Ca++ concentration. Isoproterenol did not change intracellular pH (delta pH = 0.006 +/- 0.006, n = 4; NS) while phenylephrine increased it significantly (delta pH = 0.055 +/- 0.011, n = 8; p less than 0.002). Moreover, there was a statistically significant correlation between delta ES and delta pH (R2 = 0.532; p less than 0.05) when phenylephrine was present. This alkalinization as well as the increased contractility was antagonized by treatment with ethyl isopropyl-amiloride (10 microM), a selective Na+/H+ inhibitor (delta ES = 0.09 +/- 0.07, n = 6; NS and delta pH = -0.001 +/- 0.011, n = 6; NS). Thus, alpha-adrenergic stimulation in isolated cardiac cells exerts a positive inotropic effect and this is associated with a significant intracellular pH alkalinization. In contrast, the marked inotropic action of beta-stimulation does not involve any intracellular pH modulation. Therefore, it seems likely that, in myocardial cells, an increased myofilament responsiveness due to the alkalinization could represent a possible mechanism for the positive inotropic effect mediated by alpha-adrenergic stimulation.

Animals↗
PubMed1991

Relationship between urinary neopterin excretion and islet cell antibodies in type 1 (insulin-dependent) diabetes.

Neopterin is specifically produced by interferon-activated macrophages, and it may be considered a marker of cellular immunity. In 40 newly diagnosed and 38 longer standing type 1 (insulin-dependent) diabetics the relationship between urinary neopterin levels and islet cell antibodies (ICA) was investigated. Raised urinary neopterin levels were found in 30 ICA positive (mean +/- SD: 729.8 +/- 602.1 mumol/mol creatinine, p = 0.0001) and 10 ICA negative (433.4 +/- 191.2 mumol/mol creatinine, p = 0.0005) diabetics at onset of disease compared with age-matched control subjects (118.1 +/- 33.2 mumol/mol creatinine). No significant difference in urinary neopterin levels was observed between diabetic groups. After the first stages of disease (greater than 5 months from onset), a significant difference (p = 0.0002) in urinary neopterin excretion was found between longer standing ICA positive patients and controls, but not between ICA negative diabetics and controls. In longer standing diabetics, neopterin levels were significantly higher in ICA positive patients than in ICA negative patients (544.6 +/- 341.3 versus 201.7 +/- 180 mumol/mol creatinine, p = 0.0002). No correlation between newly diagnosed or longer standing patients and HbA1c levels was found. Our results suggest that increased neopterin excretion in type 1 diabetes seems to be a sensitive indicator for the activation of cell-mediated immunity even when ICA are undetectable.

Adolescent↗
PubMed1991

Antiarrhythmic effect of L-propionylcarnitine in isolated cardiac preparations.

The effects of L-propionylcarnitine on reperfusion-induced ventricular arrhythmias were studied in isolated hearts from spontaneously hypertensive rats. During reperfusion, 60% (n = 15) of the hearts from control spontaneously hypertensive rats hearts developed irreversible ventricular fibrillation. In contrast, irreversible ventricular fibrillation did not occur in hearts from normotensive Wistar Kyoto rats (n = 11, p less than 0.01). In a second group of spontaneously hypertensive rats, the addition of 10(-6) M L-propionylcarnitine to the medium during ischemia and reperfusion reduced the incidence of irreversible ventricular fibrillation to 14% (n = 14, p less than 0.05 versus control spontaneously hypertensive rats, NS versus Wistar Kyoto rats). Concentrations of L-propionylcarnitine from 10(-6) to 10(-2) M were tested on isolated guinea pig papillary muscles using microelectrodes. Resting potential, action potential amplitude, action potential duration and active tension were not modified by L-propionylcarnitine; and 10(-3) M L-propionylcarnitine did not influence the oscillatory afterpotentials induced by digitalis. We conclude that reperfusion ventricular arrhythmias are more severe in spontaneously hypertensive rats than in Wistar Kyoto rats and that the antiarrhythmic effect of L-propionylcarnitine in spontaneously hypertensive rats is mediated by myocardial protection from damage induced by reperfusion.

Animals↗
PubMed1990

[Immunogenetic and functional study of first-degree relatives of patients with type I diabetes mellitus for identifying prediabetic subjects].

Insulin dependent diabetes mellitus is an autoimmune disease with HLA-related genetic susceptibility. There is a latent phase before overt disease. During this phase islet cell antibodies (ICA) as a marker of humoral autoimmunity are detected and i.v. glucose tolerance test (IVGTT) is decreased. The aim of our work was to correlate IVGTT, HLA typing and ICA testing in all siblings of IDDM patients in order to identify high risk subjects (HRS). IVGTT showed significantly lower insulin levels in siblings vs controls (P less than 0.0001). This phenomenon could be caused by HLA unrelated genetic predisposition to low insulin secretion. Insulin level values of ICA+ siblings were lower than those of ICA- siblings, even if the difference was not significant.

Autoantibodies↗
PubMed1990

Clinical suspicion of pancreatic neoplasm: does echo-guided fine-needle biopsy modify patient management?

The following parameters were retrospectively evaluated in 64 patients with suspected pancreatic neoplasm: (1) time required to obtain cytohistologic diagnosis, (2) days in hospital, (3) number and type of surgical operations, and (4) total hospital costs. Echo-guided fine needle biopsy (FNB) was performed on 34 patients (FNB group) and in a further 30 patients diagnostic workup did not include percutaneous biopsy (laparotomy group). Both diagnostic and hospital stay were shorter (8 and 7 days, respectively) in the FNB group than in the laparotomy group. In the FNB group, surgery was avoided in 18 patients, while in the laparotomy group 18 explorations proved diagnostic alone. Finally, FNB was shown to reduce hospital costs by 23%.

Biopsy, Needle↗
PubMed1990

ABO blood groups and cancer of the pancreas.

Few investigations discussing an association between ABO blood groups and pancreatic cancer exist. We have selected a series of 224 patients with histologically-confirmed pancreatic cancer, and their ABO blood groups distribution was compared with two control groups: 7086 patients with various diseases (Group 1) and 7320 voluntary blood donors (Group 2). There was an increased number of pancreatic cancer among the patients with blood group B (relative risk 1.5 vs Group 1 p = 0.021; 1.7 vs Group 2 p = 0.0025) and a decreased number in patients with blood group O, when compared with the two control groups.

ABO Blood-Group System↗
PubMed1990

Cardiac aging, calcium overload, and arrhythmias.

The effect of aging was tested on experimental ventricular arrhythmias in isolated heart preparations from normal Wistar rats (NWR), Wistar Kyoto rats (WKY), and spontaneously hypertensive rats (SHR). Delayed afterdepolarizations and triggered activity induced by high-calcium perfusion (16 mM) in isolated papillary muscles were more frequent in the 24-month-old than in 6-month-old NWR. Reperfusion-VA were more severe in 14-month-old SHR than in WKY. The authors have previously shown that: (1) reperfusion- and reoxygenation-induced VA, in the isolated Langendorff perfused heart, were significantly more severe and frequent in 24-month-old than in 6-month-old NWR; (2) no age-related difference in the incidence of programmed electrical stimulation (PES, train of stimuli + 1 or 2 extrastimuli)-induced VA was observed in isolated NWR hearts during control perfusion, after coronary artery ligation or during hypoxia; (3) on the contrary, the incidence of PES-induced VA was significantly higher in isolated hearts from 14-month-old SHR than from 3-month-old SHR, and 3-month-old and 14-month-old WKY. It was concluded that "physiological" aging is associated with a higher propensity to calcium-related VA, while "pathological" aging characterized by hypertension of long duration increases the incidence of PES-induced VA, probably caused by myocardial fibrosis, which could facilitate reentry.

Aging↗
PubMed1990

Ultrasound-Doppler diagnosis of Budd-Chiari syndrome.

We report a case of apparently idiopathic Budd-Chiari syndrome, diagnosed by ultrasound and Doppler sonography, in a patient with latent myeloproliferative disease. This case proves that Doppler sonography shows in the hepatic veins a flow pattern suggestive of partial thrombotic obstruction. Moreover, we suggest that the search for a latent myeloproliferative disorder, by means of the spontaneous erythroid colonies formation in culture of bone marrow or blood mononuclear cells, should be routinely included in the diagnostic evaluation of each case of hepatic vein thrombosis without other recognizable causes.

Blood Flow Velocity↗
PubMed1990

Advanced colon cancer: staging and prognosis by CEA test.

The carcinoembryonic antigen (CEA) test was studied in 54 patients with advanced stages of colon cancer which was treated with high doses of folinic acid + fluorouracil. The CEA test correlates evaluated included: prognostic value, performance status, metastatic pattern, histologic grading, predictive value for response to chemotherapy, and value differences in cases with partial response to therapy. CEA levels less than 5 ng/ml corresponded to a greater survival time than did levels greater than 5 ng/ml. A correlation of CEA with performance status and with metastatic pattern was demonstrated. A progressive increase in average CEA values corresponded to increases in neoplastic mass. Although CEA levels were not found to be an index for predicting the response to chemotherapy, there was a significant different between pre- and posttreatment levels for partial response. The results suggest that CEA offers an additional criterion for evaluating the response of colon cancer to chemotherapy and it also has a role in the staging of advanced disease.

Adult↗
PubMed1990

Circulating immune complexes detected by a direct nephelometric assay and acute phase proteins in malignant tumors.

Circulating immune complexes (CIC) were previously reported to be higher in extended cancer rather than in localized one, by a few groups of investigators as well as by ourselves. The techniques employed were quite different in each study. We described a "direct" laser nephelometric assay. At the same time we determined the serum levels of 4 acute phase proteins (AFP)--alpha 2 macroglobulin, C reactive protein, haptoglobin, alpha 1 acid glycoprotein--by conventional light scattering method, in order to investigate on other possible "immune-modulating" factors. The possible correlations either with prognosis or clinical stage are looked for; the hypothetical behaviour of CIC as one of the serum "blocking factors" and of acute phase reactant as "immune modulating" proteins are discussed. The data concerning the techniques able to remove CIC from the blood stream of the cancer patients were also showed (plasmapheresis and immunoadsorption).

Acute-Phase Proteins↗
PubMed1990

Extramedullary hematopoiesis involving the esophagus in myelofibrosis.

In this report, we describe a case of myelofibrosis with myeloid metaplasia; a 53-yr-old man was splenectomized for a massively enlarged spleen in which multiple foci of myeloid metaplasia were histologically demonstrated. The patient was referred to us for endoscopic examination, following the repeated occurrence of melena. Upper gastrointestinal endoscopy revealed two active ulcerative lesions in the bulb, and only a moderate erythema in the lower third of the esophagus, which showed no varices. There was no endoscopic evidence of active or recent bleeding. Subsequent histologic examination of biopsies taken from the esophageal lesion surprisingly revealed the presence of hematopoietic tissue.

Biopsy↗
PubMed1989

Effects of verapamil on reoxygenation and programmed electrical stimulation-induced ventricular arrhythmias in the isolated heart.

The antiarrhythmic effect of verapamil was tested on spontaneous ventricular arrhythmias during reoxygenation after 15 min of glucose-free hypoxia and on programmed electrical stimulation-(8 stimuli + 1 or 2 extrastimuli) induced ventricular fibrillation in isolated Langendorff perfused guinea pig hearts. Verapamil (1 mg/l) added during hypoxia and reoxygenation significantly reduced, during reoxygenation, the incidence of arrhythmias (46%, N = 13 vs. controls 87%, N = 30; P less than 0.01), of ventricular fibrillation (0%, N = 13 vs. controls 70%, N = 30; P less than 0.001) and of programmed stimulation-induced ventricular fibrillation (0%, N = 10 vs. controls 100%, N = 16). No effect was observed on programmed stimulation-induced ventricular fibrillation during hypoxia (90%, N = 10 vs. controls 100%, N = 10). Verapamil added during reoxygenation reduced the incidence of reoxygenation arrhythmias and ventricular fibrillation (47% and 29%, N = 17, P less than 0.01 and P less than 0.05 vs. controls, respectively) but it had no effect on programmed stimulation-induced ventricular fibrillation (100%, N = 10). It is likely that verapamil exerts its antiarrhythmic effect by preventing cellular calcium overload during hypoxia and reoxygenation.

Animals↗
PubMed1989

Programmed electrical stimulation-induced arrhythmias in isolated hearts from adult and senescent rats.

In isolated hearts from normal rats, we previously demonstrated an age-related increase of spontaneous ventricular arrhythmias. The aim of the present experiments was to test the possible effect of aging on ventricular arrhythmias induced by programmed electrical stimulation. Experiments were performed in isolated cardiac preparations of 6- and 24-month-old normal Wistar rat hearts. Programmed electrical stimulation (single or double premature stimuli following a stimuli train) was tested in isolated Langendorff perfused hearts during control perfusion, after left anterior descending coronary artery ligature and during global hypoxia. No significant differences were observed between adult and senescent hearts in the incidence of programmed electrical stimulation-induced ventricular arrhythmias during these three different situations. These experiments demonstrate that the cardiac "physiological" aging process is not associated with a greater propensity to programmed electrical stimulation-induced arrhythmias.

Aging↗
PubMed1989

[Medical therapy with mebendazole in hydatid cyst disease. A follow-up of 40 cases].

Mebendazole (50-60 mg/kg/day in 7-8 divided doses after fatty rich meals for at least 6 months) was given to 44 patients with cystic hydatid disease of the liver and other organs, about 1/3 having suffered from recurrences, even multiple, before beginning the pharmacological treatment. Fifteen patients underwent operation after a course of mebendazole, and macroscopic and histological degeneration of hydatid cysts was always documented; sixteen subjects were not operated due to their severe general and/or local conditions but ultrasound, radiologic (CT) and clinical evidence of cyst regression was obtained, and was closely comparable to that in the aforementioned group. Some of the patients (13) began the treatment only after conservative surgery. The mean real follow-up available at the moment is for 40 subjects because 2 patients did not show adequate compliance for the drug and in 2 additional cases it was withdrawn because of an increase in serum transaminases. The rate of recurrence was 7.5% and occurred in high-risk patients (multiple, bone, lung locations) who had, however, an additional and longer course of mebendazole with good results. The detachment of membranes and the increase of internal echoes, observed by means of ultrasonography, which was successfully applied to liver and soft tissue sites as well as the decrease in blood eosinophils when elevated before therapy, were observed to be the most sensitive indicators of early success in the medical treatment for hydatid disease, as far as the viability of parasite cysts was concerned.

Adolescent↗
PubMed1988

Gastric wall thickness in normal and neoplastic subjects: a prospective study performed by abdominal ultrasound.

Gastric wall thickness (body-antrum) was blind measured prospectively by real-time ultrasound in 58 patients (30 with gastric cancer and 28 healthy) who had previously undergone endoscopy. Gastric wall thickness on the average measured 15.933 +/- 4.471 mm in the neoplastic patients and 5.107 +/- 1.100 mm in the normal subjects. Seven millimeters was the highest value found in the normal subjects (4 cases) and the minimum value found in the neoplastic patients (1 case). Knowing the normal gastric wall thickness value on a standard ultrasound examination of the upper abdomen is useful, as ultrasound is often performed as a screening or first-step procedure, in order to address the patients with higher values toward more specific techniques.

Humans↗