Biomedical subjects

S Marangoni

Publications and source records attributed to S Marangoni.

At least 73 records · Page 4Linked to original sources

PubMed1995

Isolation of a polypeptide from Phoneutria nigriventer spider venom responsible for the increased vascular permeability in rabbit skin.

Fractionation of Phoneutria nigriventer venom by Sephadex G-10 followed by ion-exchange chromatography yields a fraction (fraction XIII) which increases microvascular permeability in rabbit skin in vivo by activating the tissue kallikrein-kinin system. One polypeptide (PNV3) with the ability to increase microvascular permeability in the rabbit skin in vivo was isolated from fraction XIII and biochemically characterized. PNV3 has 132 amino acid residues with a calculated mol. wt of 14,475. This polypeptide showed the following N-terminal sequence: AVFAIQDQPC. Amino acid analysis indicated the presence of six disulfide bridges and a high content of Glx (20%). Pairwise comparison of PNV3 amino acid sequence with 27 other spider venom polypeptides and proteins indicated that PNV3 presents high similarity (60-70%) with other toxins (Tx2.1, Tx2.5 and Tx2.6) isolated from P. nigriventer venom.

Amino Acid Sequence↗

PubMed1995

Inhibition of carrageenin-induced rat paw oedema by crotapotin, a polypeptide complexed with phospholipase A2.

1. The effect of purified crotapotin, a non-toxic non-enzymatic chaperon protein normally complexed to a phospholipase A2 (PLA2) in South America rattlesnake venom, was studied in the acute inflammatory response induced by carrageenin (1 mg/paw), compound 48/80 (3 micrograms/paw) and 5-hydroxytryptamine (5-HT) (3 micrograms/paw) in the rat hind-paw. The effects of crotapotin on platelet aggregation, mast cell degranulation and eicosanoid release from guinea-pig isolated lung were also investigated. 2. Subplantar co-injection of crotapotin (1 and 10 micrograms/paw) with carrageenin or injection of crotapotin (10 micrograms/paw) into the contralateral paw significantly inhibited the carrageenin-induced oedema. This inhibition was also observed when crotapotin (10-30 micrograms/paw) was administered either intraperitoneally or orally. Subplantar injection of heated crotapotin (15 min at 60 degrees C) failed to inhibit carrageenin-induced oedema. Subplantar injection of crotapotin (10 micrograms/paw) also significantly inhibited the rat paw oedema induced by compound 48/80, but it did not affect 5-HT-induced oedema. 3. In adrenalectomized animals, subplantar injection of crotapotin markedly inhibited the oedema induced by carrageenin. The inhibitory effect of crotapotin was also observed in rats depleted of histamine and 5-HT stores. 4. Crotapotin (30 micrograms/paw) had no effect on either the histamine release induced by compound 48/80 in vitro or on the platelet aggregation induced by both arachidonic acid (1 nM) and platelet activating factor (1 microM) in human platelet-rich plasma. The platelet aggregation and thromboxane B2 (TXB2) release induced by thrombin (100 mu ml-1) in washed human platelets were also not affected by crotapotin. In addition, crotapotin (10 microg/paw) did not affect the release of 6-oxo-prostaglandin Fla, and TXB2 induced by ovalbumin in sensitized guinea-pig isolated lungs.5. Our results indicate that the anti-inflammatory activity of crotapotin is not due to endogenous corticosteroid release or inhibition of cyclo-oxygenase activity. It is possible that crotapotin may interact with extracellular PLA2 generated during the inflammatory process thereby reducing its hydrolytic activity.

6-Ketoprostaglandin F1 alpha↗

PubMed1995

A quick procedure for the isolation of dimeric piratoxins-I and II, two myotoxins from Bothrops pirajai snake venom. N-terminal sequencing.

Two myotoxins, MP-I and MP-II, from Bothrops pirajai snake venom, have been purified by a quick high performance liquid chromatography (HPLC) procedure. Based on the HPLC coelution profile, amino acid composition, N-terminal sequence, polyacrylamide gel electrophoresis (PAGE) migration, as well as lack of phospholipase-A2 (PLA2) and proteolytic activities, MP-I and MP-II were identified as piratoxin-I (PrTX-I) and II (PrTX-II), respectively. This procedure affords, aside the reduced operation time, a high yield (35% of the applied sample in terms of A280nm) of MP-I, which is the major myotoxin of the venom. The N-terminal sequences of MP-I, MP-II, PrTX-I and PrTX-II, up to the 51st, 41st, 46th and 39th residues, respectively, have been determined, revealing MP-I (and hence PrTX-I) as a Lys-49 PLA2-like myotoxin. Both MP-I and MP-II have been shown, by SDS-PAGE, to occur in dimeric isoforms.

Amino Acid Sequence↗

PubMed1995

Respiratory and haemodynamic modifications during right heart catheterization in COLD patients.

Noninvasive measurement of the systolic time intervals is a routine procedure for the determination of myocardial performance, even in subjects without clinical or electrocardiographic signs of cardiopathy. Statistically significant differences in pre-ejection period (PEP) and PEP/left ventricular ejection time (LVET) between days and between observations were demonstrated by Levi et al. A high correlation between systolic time intervals and catecholamines was recorded. The aim of the present study was to evaluate the spontaneous modifications in pulmonary and cardiac parameters during a stressful situation, such as right heart catheterization. Seventeen patients with chronic obstructive lung disease (COLD) underwent right heart catheterization. Heart rate (HR), systemic artery pressure (SAP), pulmonary artery pressure (PAP), cardiac output (Q'c), cardiac index (CI), systolic stroke volume (SV), respiratory rate (RR), minute ventilation (V'E), oxygen consumption (V'O2), carbon dioxide production (V'CO2), their ratio (RQ), arterial and venous O2 and CO2, systolic time intervals (total electromechanical interval (QS2), LVET, PEP, PEP/LVET), total pulmonary resistance (TPR), adrenaline (A), and noradrenaline (NA) were recorded at the beginning of the test and 20, 40, 60 and 80 min thereafter. Analysis of variance (ANOVA) showed significant differences between the observations for systolic pulmonary artery pressure (SPAP), Q'c, V'O2, V'CO2, V'E, PEP/LVET, and NA. In conclusion, it is necessary to take into account spontaneous modifications in pulmonary haemodynamic parameters following a stressful situation, such as a catheterization, when studying the effects of drugs such as vasodilators and vasoactive agents.

Cardiac Catheterization↗

PubMed1994

Crotoxin induces aggregation of human washed platelets.

Crotoxin, the main toxic component isolated from the venom of the South American rattlesnake Crotalus durissus terrificus, is a reversible protein complex composed of a non-toxic non-enzymatic acidic polypeptide (crotapotin) and a toxic basic phospholipase A2 (PLA2). In this study, we have evaluated the ability of crotoxin to induced aggregation in human washed platelets. Human washed platelet aggregation was monitored in a Payton aggregometer and thromboxane B2 (TXB2) release measured by direct radioimmunoassay (RIA). Crotoxin (15-50 micrograms/ml) produced dose-dependent and irreversible human washed platelet aggregation, which was inhibited by pre-incubation of the platelets with sodium nitroprusside (50-500 microM) or iloprost (8-80 nM). Crotoxin also induced TXB2 release (207 +/- 8 ng/ml, n = 6), and although indomethacin significantly reduced the release of TXB2 (to 23.5 +/- 5 ng/ml, P < 0.001, n = 6), it did not inhibit crotoxin-induced aggregation. Our results clearly demonstrate that crotoxin induces human washed platelet aggregation and that this phenomenon is independent of the formation of pro-aggregatory arachidonic acid metabolites.

Amino Acid Sequence↗

PubMed1994

Isolation and partial characterization of an anti-bothropic complex from the serum of South American Didelphidae.

An anti-bothropic fraction (ABF) with anti-Bothrops jararaca venom activity tested in mice was isolated from the serum of some South American Didelphidae (Didelphis marsupialis, Philander opossum and Lutreolina crassicaudata) by DEAE-Sephacel chromatography. ABF from D. marsupialis was shown to be 12 times more active in protection assays on a weight basis than the serum proteins. A similar fraction obtained from Metachirus nudicaudatum serum was shown to be inactive. An anti-bothropic complex (ABC) was isolated from D. marsupialis ABF. HPLC gel permeation chromatography of ABC from D. marsupialis indicated the presence of a main peak with mol. wt of 84,000. SDS-PAGE of this ABC showed the presence of two subunits of 48,000 and 43,000. The active ABF isolated from P. opossum and L. crassicaudata also showed the presence of these subunits by SDS-PAGE. Isolation of the 48,000 mol. wt D. marsupialis subunit by HPLC-hydrophobic interaction chromatography demonstrated that the 43,000 subunit was essential for the protective action of the complex. Both subunits from D. marsupialis, P. opossum and L. crassicaudata were Western-blotted and N-terminal sequenced. No N-terminal amino acid was found for the 43,000 subunit, whereas for the 48,000 subunit a high degree of homology was found: D. marsupialis: H2N-L K A M D P T P P L W I K T E X P . ; L. crassicaudata: H2N-L K A M D P T P P L W I Q T E . . . ; P. opossum: H2N-L K A M D T T P E . . . No significant homology with known proteins was detected.

Amino Acid Sequence↗

PubMed1994

Respiratory muscle function and exercise capacity in multiple sclerosis.

Patients with multiple sclerosis (MS) show a poor exercise tolerance. A reduction in respiratory muscle strength has also been reported. The purpose of this study was to evaluate whether reduction in exercise tolerance was related to respiratory muscle dysfunction. Twenty four multiple sclerosis patients (mean +/- SD age: 48 +/- 9 yrs, duration of illness 12.2 +/- 6 yrs, severity of illness as assessed by Expanded Disability Scale Score (EDSS) 5.3 +/- 2), underwent detailed evaluation of lung function tests, arterial blood gas analysis, respiratory muscle strength and endurance, and exercise test on an arm ergometer. Sixteen of the 24 patients were able to perform the exercise test (Group I), whilst the other eight were not (group II). Arterial blood gases and lung function tests were normal for both groups. Respiratory muscle strength as assessed both by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) was significantly reduced (MIP 18-76 cmH2O; MEP 16-82 cmH2O) compared to predicted values. Inspiratory muscle endurance time was significantly reduced in Group II in comparison to Group I (247 +/- 148 vs 397 +/- 154 s, respectively). Both MIP and MEP were significantly related to inspiratory muscle endurance time. Endurance time, MIP and MEP were inversely significantly related to duration of illness, whilst only endurance time was significantly related to Expanded Disability Scale Score.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Analysis↗

PubMed1994

Cardiological monitoring in a respiratory intermediate intensive care unit.

The appearance, in the last few years, of respiratory intermediate intensive care units (RIICU) has created a requirement of close collaboration among different physicians. The role of a cardiologist in a RIICU is well recognized as an important component to the pulmonolgist. The diagnostic tools for the cardiologist in a RIICU should be separated into two sections: in the first one specific and mandatory devices for monitoring are included; in the other second choice instruments and methods are considered. A 24h ECG monitoring system, noninvasive Pa recording, central venous pressure evaluation set from peripheral vein, pumps for infusive therapies and cardiac echo-Doppler have to be considered necessary. Specific ECG monitoring system and right heart catheterization or arterial cannulation cannot be mandatory for these patients. The presence of a cardiologist in a RIICU can facilitate adequate cardiac monitoring in respiratory patients.

Cardiology↗

PubMed1994

Hygroscopic condenser humidifiers in chronically tracheostomized patients who breathe spontaneously.

The aim of this study was to test the usefulness of hygroscopic condenser humidifiers on secretion and on inspired gas temperature in tracheostomized patients. Forty spontaneously breathing chronically tracheostomized patients were divided into two groups: Group 1 received a hygroscopic condenser humidifier connected to the tracheostomy, 24 h daily for 10 days; Group 2, without any protection system, was chosen as the control group. The daily number of tracheal suctions, quantity of aspirate and thickness and colouring of secretions was evaluated. At baseline, and at days 5 and 10, patients were submitted to blood gas analysis, respiratory function tests and sputum analysis. The temperature of gases breathed was measured at rest and during a hyperventilation test, with and without the hygroscopic condenser humidifier. Statistically significant differences were found in thickness and colouring of secretions between the two groups during the period of 10 days. Group 2 showed a significantly greater trend in number of bacteria than Group 1. The group with the hygroscopic condenser humidifier showed respiratory function improvement over time for forced expiratory volume in one second (FEV1) and tidal volume (VT), maximal inspiratory pressure (MIP), and maximal voluntary ventilation (MVV) in comparison to the control group, who did not. Significant differences in the temperature between rest and hyperventilation, with and without a hygroscopic condenser humidifier were also found. In conclusion, a hygroscopic condenser humidifier may be useful in chronically tracheostomized patients who breathe spontaneously, improving viscosity and colouring of secretions, preventing further bacterial colonization, heating inspiratory flow, and helping to improve the functional outcome.

Aged↗

PubMed1993

Identification of a new vascular smooth muscle contracting polypeptide in Phoneutria nigriventer spider venom.

The fractionation of Phoneutria nigriventer spider venom by gel filtration (Sephadex G-10-120) followed by ion-exchange chromatography (microgranular CM-cellulose-52) resulted in sixteen fractions (CI to CXVI) from which CVII+VIII, CIX and CX+XI caused dose-dependent and short-lived contractions of both arterial and venous rabbit vessels. Fraction CX+XI was further purified by a reverse phase HPLC, and a contractile polypeptide (PNV2) was isolated. The amino terminal sequence of PNV2 (LAKRADICQPGKTSQRACET) indicated that it represents a pure polypeptide consisting of a single chain. Furthermore, the amino acid analysis of PNV2 revealed the presence of four disulfide bridges, a high content in Lys (14%), Glx (11%), and the absence of His. The global amino acid composition showed that this polypeptide is composed of 102 residues (Trp not included) with a calculated molecular weight of 12,114. Whether this peptide is responsible for the vascular alterations observed in Phoneutria envenomation, such as lung edema and priapism, remains to be further investigated.

Amino Acid Sequence↗

PubMed1993

Bothropstoxin-I: amino acid sequence and function.

The complete amino acid sequence of bothropstoxin-I (BthTX-I), a myotoxin isolated from Bothrops jararacussu snake venom, is reported. The results show that BthTX-I is a Lys49 phospholipase A2 (PLA2)-like protein composed of a single polypeptide chain of 121 amino acid residues (M(r) = 13,720), containing one methionine and 14 half-cystines. Although deprived of any detectable PLA2 activity, BthTX-I reveals a high degree of sequence homology with Asp49-PLA2s and with other Lys49-myotoxins. Critical mutations--such as Leu5 for Phe5; Gln11 for X11; Asn28 for Tyr28; Leu32 for Gly32; Lys49 for Asp49; and Asp71 for Asn71--which are apparently involved with the decreasing or elimination of PLA2 activity, have been detected. The same mutations occurred in myotoxin II from Bothrops asper venom, but five extra changes--namely, Pro90 for Ser90; Gly111 for Asn111; His120 for Tyr120; Phe124 for Leu124; and Pro132 for Ala132--have been found relative to myotoxin II.

Amino Acid Sequence↗

PubMed1993

Biochemical characterization of a vascular smooth muscle contracting polypeptide purified from Phoneutria nigriventer (armed spider) venom.

Biochemical characterization of a vascular smooth muscle contracting polypeptide purified from Phoneutria nigriventer (armed spider) venom. Toxicon 31, 377-384, 1993. Crude Phoneutria nigriventer venom was fractionated by Sephadex, ion-exchange and reverse-phase high performance liquid chromatography. One protein (PNV1) with spasmogenic activity in rabbit vascular smooth muscle was isolated and biochemically characterized. PNV1 has 125 amino acid residues and a calculated mol. wt of 13,899. Special features of the amino acid composition of PNV1 are the presence of two disulfide bridges and the high percentage (27%) of Asx and Glx. The N-terminal amino acid sequence indicates that PNV1 is different from other polypeptides isolated from Phoneutria nigriventer venom.

Amino Acid Sequence↗

PubMed1992

Physical rehabilitation in coronary patients who have suffered from episodes of cardiac failure.

The effects of bicycle training for 5 weeks were evaluated in 12 patients after myocardial infarction with left ventricular dysfunction (left ventricular ejection fraction < 40%) and at least one episode of cardiac failure in the past. The patients were divided into two groups of six according to the Weber classification: Group B (VO2/kg/min: 16-20) and Group C (VO2/kg/min: 10-15). Cardiopulmonary and hemodynamic parameters were evaluated during a maximal exercise test and a simultaneous catheterization of the right side of the heart before and after the training. An increase in the capacity for work was recorded in Group B (p < 0.02), while Group C remained unchanged. A statistically significant increase in minute ventilation (p < 0.05) and VO2/kg/min (p < 0.0006) was recorded in Group B. Group C showed an increase in the mean pulmonary arterial pressure (p < 0.03). All of the other parameters remained unchanged after training. We conclude that physical rehabilitation improves the tolerance to exercise in patients with a mildly depressed cardiac function (Group B) but not in patients with a very depressed cardiac function (Group C).

Cardiac Output↗

PubMed1992

Acute exacerbations in severe COLD patients. Treatment using positive pressure ventilation by nasal mask.

We retrospectively evaluated the clinical effectiveness of a treatment schedule with intermittent positive pressure ventilation via nasal mask in 49 patients with acute exacerbations of COLD. According to the ability to successfully tolerate a preliminary trial with NIPPV, patients were submitted either to standard treatment plus NIPPV (25 patients) or to ST alone (24 patients). The ST consisted of medical, oxygen and physical therapy. The NIPPV was delivered by a volume cycled ventilator in control mode at least 4 h a day for five consecutive days a week, for three weeks. Comparison of baseline with measurements performed after 10 and 21 days of treatment respectively showed a significant improvement in PaO2 and in PaCO2 in both groups. After 21 days of treatment, VC, FEV1, inspiratory muscle strength, and dyspnea significantly improved in both groups. No significant difference was found between groups at any time of treatment. We conclude that the treatment schedule of NIPPV used is not more effective than ST alone in acute exacerbations of COLD.

Aged↗

PubMed1992

Time course of pulmonary function before admission into ICU. A two-year retrospective study of COLD patients with hypercapnia.

Changes in cardiopulmonary function were retrospectively evaluated back to two years before acute exacerbations requiring ICU admission in 16 COLD patients with chronic hypercapnic respiratory insufficiency (age: 61 +/- 6 years, group A). Fifteen hypercapnic COLD patients matched for age, sex, lung function, and blood gas values not requiring an ICU admission in a period of two years, served as control subjects (age: 66 +/- 7, group B). Periodic assessments of spirometry, arterial blood gas values, echocardiography, body weight, and red blood cell count performed in stable state were compared for differences between groups and changes over a period of two years. The results indicated that basal body weight, rate of deterioration over time in FEV1, VC, blood gas values, bicarbonates, and RVD may be related to the necessity of ICU admission in COLD patients with hypercapnic respiratory insufficiency.

Aged↗

PubMed1992

Right ventricular diastolic function in chronic obstructive lung disease.

Early detection of diastolic dysfunction in chronic obstructive lung disease (COLD) patients could have great prognostic value. Echocardiography has been shown to be a useful technique in studying left ventricular diastolic function. A noninvasive method of studying right ventricular diastolic function has not yet been reported. Pulsed Doppler echocardiography was used to assess right ventricular diastolic function in three groups of subjects: Group I: 35 COLD patients with pulmonary hypertension; Group II: 32 COLD patients without pulmonary hypertension; and Group III: 18 control subjects. Ratios between peak atrial filling velocity (A) and peak early filling velocity (E) (A/E), deceleration half times of the right ventricular rapid filling wave (DHT), and the interval between pulmonary valve closure and tricuspid valve opening (isovolumic relaxation times) (Pc-To) were significantly different in Group I in comparison to Groups II and III. Sensitivity of A/E ratio and Pc-To were 82 and 77%, respectively, and specificity 90 and 72%, respectively; positive predictive values were 90 and 75%, respectively, and negative predictive value 82 and 74% respectively. The multiple correlation coefficient between A/E, acceleration time (ACT), DHT, Pc-To and mean pulmonary artery pressure was 0.75 for Groups I and II together. In conclusion 2D echo-Doppler proved to be useful in evaluating right ventricular diastolic function in all hypertensive COLD patients, revealing a high correlation between diastolic parameters and mean pulmonary artery pressure in both normotensive and hypertensive COLD patients.

Echocardiography, Doppler↗

PubMed1990

The complete amino acid sequence of toxin TsTX-VI isolated from the venom of the scorpion Tityus serrulatus.

The complete sequence of the toxin TsTX-VI from the venom of the scorpion Tityus serrulatus Lutz and Mello is presented. The sequence has been determined by automated Edman analysis of the reduced and carboxymethylated protein as well as of the resulting peptides, obtained from S. aureus protease and tryptic digestions. TsTX-VI is composed of 62 residues and has a calculated molecular weight of 6717. Homology studies with other scorpion toxins show that TsTX-VI is more similar to the Old World than to the North American scorpion toxins. The hydropathic index indicates that TsTX-VI is more hydrophobic than Ts-gamma. Toxicity studies carried out in mice demonstrate that i.v. injection of TsTX-VI is unable to evoke the usual symptoms induced by the typical neurotoxins of this venom, but only a generalized allergic reaction. These properties are important in clarifying the relationship between primary structure and biological function of scorpion toxins.

Amino Acid Sequence↗

PubMed1990

Sudden dilatation of right ventricle in two patients with thrombosis of a mitral Björk valve detected by echocardiography: different aspects of acute and chronic overloads of the right ventricle in these patients.

Acute thrombotic obstruction of disc valve prosthesis is a rare but catastrophic event without an immediate correct diagnosis and precocious treatment (Amman et al., 1984; Assanelli et al., 1986; Copans et al., 1980; Mann et al., 1986; Gibson et al., 1974; Johnson et al., 1973; Ledain et al., 1986). That is the main reason it is important to consider each helpful sign in order to recognize such a situation. We detected an important dilatation of the right ventricle in two patients with different stages of thrombosis of mitral Björk, the first one had also a chronic dilatation of the right ventricle due to tricuspid regurgitation. The clinical and pathophysiological aspects of these unusual situations are described in this article.

Adult↗