PubMed Health⌕ Search

Biomedical subjects

G Mancinelli

Publications and source records attributed to G Mancinelli.

31 records · Page 2Linked to original sources
PubMed1989

Mechanism of spectrin degradation induced by phenylhydrazine in intact human erythrocytes.

The exposure of human erythrocytes to phenylhydrazine results in the degradation of both monomers of spectrin, a major cytoskeleton membrane protein. The degradative process, characterized by a loss of spectrin without the appearance of high-molecular-weight products, either under reducing conditions or not, is almost complete in 10 min when a 5% erythrocyte suspension is treated with 1 mM phenylhydrazine. Under these conditions, we found a loss of 62.3 and 48.5% for the alpha and beta monomer, respectively. A similar degradative extent was obtained when the membrane ghost plus cellular free extracts, were dialyzed, and the membrane ghost plus hemoglobin was exposed to 1 mM phenylhydrazine for 10 min. The presence of different proteinase inhibitors and effectors, such as EDTA, diethylenetriaminepentaacetic acid, EGTA, leupeptin, aprotinin, phenylmethylsulfonyl fluoride, pepstatin, Ca2+ and ATP plus Mg2+, in the membrane ghost plus cellular free extract system (undialyzed) did not affect the degree of the spectrin-degradative process induced by phenylhydrazine. In addition, a purified spectrin tetramer preparation exposed to 1 mM phenylhydrazine in the presence of hemoglobin was degraded to an extent comparable to that with intact cells. Our data suggest that the initial degradative step of spectrin induced by phenylhydrazine in intact erythrocytes may be ascribed more to a direct oxidative breakdown, probably involving main-chain cleavage and side-chain cleavage processes, than to an eventual proteolytic system.

Erythrocyte Membrane↗
PubMed1989

NPGB-induced inhibition of superoxide anion production by normal Lewis rat macrophages.

The treatment of Lewis rat peritoneal macrophages with p1-nitrophenyl p-guanidinobenzoate (NPGB) inhibited the superoxide anion production stimulated with phorbol myristate acetate (PMA). The addition of NPGB at the time of maximum superoxide generation was still able to block the superoxide release. It appears from these findings that NPGB may block either the activation process of the membrane bound NAD(P)H oxidase or directly on the active enzyme. Other protease inhibitors such as, epsilon-amino caproic acid (EACA), pepstatin, trans aminomethyl cyclohexane carboxylic acid (AMCA), aprotinin, and leupeptin did not inhibit the superoxide release. The superoxide anion release by the xanthine-xanthine oxidase system was not inhibited by NPGB. This finding indicates that NPGB does not itself react with superoxide. It has been also demonstrated that NPGB is a good reactant toward sulfhydryl group. The relevance of these finding to experimental allergic encephalomyelitis (EAE) is discussed.

Animals↗
PubMed1986

Isolation and biochemical characterization of the microsomal fraction from the digestive gland of mussel Mytilus galloprovincialis Lam.

A procedure to prepare microsomes from the mussel digestive gland is proposed. The data concerning the biochemical characterization of this subcellular fraction shows a typical RNA:protein ratio, but the presence of hydrolytic enzymes was also found; therefore a mixture of hydrolase inhibitors to study the different biochemical characteristics was used. The biochemical data demonstrate that glucose-6-phosphatase activity (G6Pase), a typical microsomal marker in mammalian cells, is not present in mussel digestive gland microsomes but a high non-specific phosphatase activity was detected. Benzo[a]pyrene hydroxylase activity was found to be present although in a minimal amount. The evaluation of the molecular weight of the rRNA demonstrates that the larger ribosomal subunit contains RNA of Mr 1.40 X 10(-6) (approximately 26S) and the smaller subunit is composed of RNA of Mr 0.65 X 10(-6) (18S). The data from mussel digestive gland microsomes was compared with that experimentally obtained from rat liver microsomes and discussed from a functional or an evolutionary point of view.

Animals↗
PubMedDate not supplied

DNA-dependent RNA polymerase activities in hepatopancreas nuclei from Mytilus galloprovincialis Lamarck.

It has been shown that RNA synthesis in isolated hepatopancreas nuclei from Mytilus galloprovincialis is catalyzed by three DNA-dependent RNA polymerases (I, II and III) which resemble those identified in nuclei from mammalian cells. RNA polymerase I is active at 50 mM (NH4)2SO4, catalyzes the synthesis of GMP-rich ribosomal-like RNA and is completely resistant to the toadstool toxin alpha-amanitin. RNA polymerase II and III are active at higher (NH4)2SO4 concentrations, catalyze the synthesis of DNA-like RNA and are inhibited by very low (0.5-1 microgram/ml) and high (200 microgram/ml) concentrations of alpha-amanitin, respectively. Hepatopancreas nuclei retain considerable RNAase activity. Nuclear RNA polymerase activity may be underestimated since a part of the synthetized RNA is degraded.

Animals↗
PubMedDate not supplied

[Prediction of outcome in critically ill patients using haemodynamic and oxyphoretic parameters].

OBJECTIVE: To find a predictive model for short time mortality and survival of haemodinamically instable patients. DESIGN: Prospective study on two consecutive series of critically ill patients admitted to ICU. SUBJECTS: 115 critically ill patients, subdivided in two series of 83 (47 survivors and 36 non survivors after 20 days from admission) and 32 patients (19 survivors and 13 non survivors), respectively. INTERVENTIONTS: All the patients have been monitored with a Swan-Ganz catheter. MEASUREMENTS: Oxyphoretic parameters were measured at 7 different times (T): T0 (start), T1 (after 12 hours from T0, T2 (24 hrs), T3 (48 hrs), T4 (72 hrs), T5 (96 hrs) and T6 (120 hrs). A total number of 401 recorded values of the first patients' series were used to create the predictive model for outcome (0 non survivors, 1 survivors). Stepwise logistic regression was used to create the model. Model calibration and discrimination was assessed. The model was validated using data collected from the second series. RESULTS: The probability of survival after 20 days was Pr (survive) = e(logit)/1+e(logit), with "logit" = -5,106+(-6,58E-02 SVI)+(-2,76E-03 SVR)+(0,1379 LVSWI)+(0,8933 Hb)+(-3,25E-02 VO2I)+(9,09E-02 O2ER)+(-7,89E-02 SHUNT)+PAT. For medical patients PAT = -0.568; for surgical patients PAT = -1.0525 and for politrauma PAT = 1.593. Goodness-of-fit test showed a good calibration: chi 2 = 4.267, p = 0.832. The area under the ROC curve was 0.831. The model used in the validation data set, with 199 recorded values, also showed a good calibration and discrimination (Goodness-of-fit test: chi 2 = 15.65, p = 0.111; area under the curve 0.798). CONCLUSIONS: The mathematical model we found has been validated also in the second series and the discrimination capability increases with time. Using this model we can evaluate the probability of survival at every time. Its application at different times permits a better evaluation of haemodynamically instable patient trend.

APACHE↗