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Biomedical subjects

M Romano

Publications and source records attributed to M Romano.

At least 289 records · Page 16Linked to original sources
PubMed1991

Eosinophil activation on biologic surfaces. Production of O2- in response to physiologic soluble stimuli is differentially modulated by extracellular matrix components and endothelial cells.

Production of O2- in response to FMLP, TNF, IFN-gamma, platelet activating factor, LPS, substance P, and PMA by human eosinophils in suspension and in contact with polystyrene ELISA plastic (PL) or biologic surfaces was studied. Monolayers of human endothelial cells (HEC) or PL coated with FCS, fibronectin, laminin, collagen types I and IV, fibrinogen, or fibrin were used as biologic surfaces. Only PMA and FMLP stimulated O2- generation by eosinophils in suspension. Eosinophils residing on HEC monolayers, either untreated or treated with LPS, were unresponsive to all stimuli except PMA. PMA induced O2- generation by eosinophils on all surfaces; FMLP on all surfaces but HEC monolayers; TNF and platelet-activating factor only on PL, fibrinogen, and fibrin; LPS and substance P only on PL. PMA was equally effective on eosinophils on surfaces and in suspension, whereas the effect of FMLP was greater on eosinophils on surfaces than on eosinophils in suspension. IFN-gamma was ineffective on any of the surfaces tested. These results indicate that biologic surfaces may profoundly affect the ability of eosinophils to respond with a respiratory burst to physiologically relevant soluble stimuli, the effect varying according to the nature of both the stimulus and the surface. Since the respiratory burst generates products of oxygen reduction that are toxic to several tissue components, it follows that biologic surfaces may modulate eosinophil-induced tissue injury.

Endothelium, Vascular↗
PubMed1991

The hemoglobins of the cold-adapted Antarctic teleost Cygnodraco mawsoni.

The blood of the teleost Cygnodraco mawsoni, of the endemic Antarctic family Bathydraconidae, contains a major hemoglobin (Hb 1), accompanied by a minor component (Hb 2, about 5% of total). The two hemoglobins have identical alpha chains and differ by the beta chain. The complete amino acid sequence of the three chains has been elucidated, thus establishing the primary structure of both hemoglobins. The sequences show a 53-65% identity with non-Antarctic poikilotherm fish species; on the other hand, a very high degree of similarity (83-88%) has been found between Hb 1 and the major component of another Antarctic species of a different family. The hemoglobin functional properties relative to oxygen binding have been investigated in intact erythrocytes, 'stripped' hemolysate and purified components of C. mawsoni. The hemoglobins display the Bohr and Root effects, indicating fine regulation of oxygen binding by pH and by the physiological effectors organic phosphates.

Adaptation, Physiological↗
PubMed1991

Hepatitis C virus infection is an additive risk factor for development of hepatocellular carcinoma in patients with cirrhosis.

The aim of the present study was to evaluate whether hepatitis C virus plays any role in the development of hepatocellular carcinoma in cirrhotic patients. The role of age, sex, alcohol abuse, and infection by other hepatitic viruses, such as hepatitis B and Delta viruses, was also assessed. We found that mean age and male/female ratio were significantly higher in patients with HCC plus liver cirrhosis than in those with liver cirrhosis alone. Also, the prevalence of HCV infection was found to be higher in HCC patients compared to cirrhotics. Further, by means of multiple logistic regression, we evaluated the independent role of each variable in the development of HCC. Age, male sex, and to a lesser degree, HCV infection, as assessed by anti-HCV positivity, were the only risk factors which significantly correlated with the development of HCC. Moreover, when age and sex were excluded from the statistical model, HCV infection, but not HBV, HDV, and alcohol abuse, appeared to be associated with HCC. In conclusion, based on these data, age and male sex are the most important factors for the development of hepatocellular carcinoma in cirrhotic patients. Hepatitis C virus, at least in the Mediterranean area, may play a role as an additive risk factor of HCC in patients suffering from liver cirrhosis.

Age Factors↗
PubMed1991

Effect of tyrosine on the potentiation by aspartame and phenylalanine of metrazol-induced convulsions in rats.

Male rats were treated by oral intubation with tyrosine (Tyr), at doses of 0.5 and 1.0 g/kg body weight, alone or together with 1 g aspartame (APM)/kg body weight, or an equivalent dose of phenylalanine (Phe; 0.5 g/kg body weight); the effects on seizures induced by an effective dose of metrazol (ED50) were observed. Tyr (0.5 g/kg body weight) had a protective effect against the Phe-potentiation of metrazol-induced clonic-tonic convulsions. At the same dose Tyr had no effect on the seizure-promoting activity of APM, but at 1 g/kg it reduced the proconvulsant potential of the sweetener. Analysis of the brain and plasma amino acid concentrations indicated that the Tyr to Phe ratio tended to be enhanced in Tyr-Phe treated rats compared with those treated with Phe alone. This ratio remained essentially constant in the brain of APM-treated rats, compared with those treated with APM plus 1 g Tyr/kg body weight, whereas an increase in this ratio in the plasma was observed. These results confirm that Tyr antagonizes the proconvulsant effect of Phe and APM and they further suggest that no simple relationship exists between the relative brain concentrations of the two amino acids and the response to metrazol convulsions.

Animals↗
PubMed1991

Interspecies and interstrain studies on the increased susceptibility to metrazol-induced convulsions in animals given aspartame.

The ability of aspartame (APM) to increase the susceptibility to metrazol-induced convulsions was studied in two strains of mice (CD1 and DBA/2J) and in guinea-pigs. Rats were included as known positive controls. Plasma and brain levels of phenylalanine (Phe) and tyrosine (Tyr) were measured in CD1 mice and guinea-pigs at various intervals after a dose of 1 g APM/kg body weight (administered orally to mice and ip to guinea-pigs). In mice, peak levels of Phe and Tyr were observed in plasma after 30 min and in brain after 60 min. In guinea-pigs peak plasma levels of Phe and Tyr occurred 30 min after treatment. Phe was at a maximum in guinea-pig brain after 30 min, while Tyr levels reached a peak at 120 min. In further experiments Phe and Tyr levels were measured 1 hr after APM doses of 0.5, 0.75 or 1 g/kg. In CD1 mice, plasma Phe and Tyr levels were increased significantly only at the highest dose, whereas in brain, Tyr concentrations were significantly increased by 0.75 or 1 g APM/kg and Phe was significantly increased by all three doses. In the guinea-pig, plasma Phe and Tyr were increased significantly only by 1 g APM/kg and in brain this dose significantly raised only the Phe levels. Monoamine and metabolite levels were determined in the brain striata of CD1 and DBA/2J mice 1 hr after the oral administration of 1 or 2 g APM/kg body weight; no differences from control values were found in either strain. The studies of potentiation of metrazol-induced convulsions showed that APM, at doses of up to 2 g/kg body weight, had no such effect in mice or guinea-pigs. In contrast, as expected, the potentiation was significant in the rat at 1 g/kg.

Animals↗
PubMed1991

Effect of iodinated contrast media on the synthesis and metabolism of leukotriene B4.

To investigate whether the endogenous vasoactive substrate, leukotriene B4 (LTB4), was induced in adverse reactions observed after intravenous injection of iodinated contrast media (CM), the authors measured the in vitro production and metabolism of LTB4 by human polymorphonuclear leukocytes (PMNs) after stimulation with different doses of commercial CM preparations: iopamidol, 300 mg I/mL; iodamide, 300 mg I/mL; iohexol, 300 mg I/mL; ioxaglate, 320 mg I/mL; and the experimental preparation, iomeprolo. This study showed that the CM studied do not stimulate the production or metabolism of LTB4 by isolated human blood PMNs. All of the CM studied except iodamide do not inhibit the production or metabolism of LTB4 in PMNs stimulated by A23187. The in vitro hepatic microsomal oxidation of exogenous LTB4 to (omega-1)OH LTB4 and omega-OH LTB4 was inhibited by all the CM studied. LTB4 production by PMNs seems not to play a major role in anaphylactoid reactions observed after iodinated CM. However, a transient blockade by CM of LTB4 metabolism, leading to an increase of steady-state concentrations of LTB4, could not be excluded by these experiments.

Animals↗
PubMed1991

Failure of atrial natriuretic factor to increase with saline load in patients with dilated cardiomyopathy and mild heart failure.

To investigate whether the response of atrial natriuretic factor (ANF) to volume expansion is impaired in the early stages of dilated cardiomyopathy, the effects of saline load (SL; 0.25 ml/kg.min for 120 min) were assessed in 12 patients with dilated cardiomyopathy and asymptomatic to mildly symptomatic heart failure (HF) and in nine normal subjects (N). SL increased plasma ANF levels in N (from 14.3 +/- 2 to 19.5 +/- 3 and 26 +/- 4 pg/ml, at 60 and 120 min, respectively, P less than 0.001), but not in HF (from 42.9 +/- 9 to 45.9 +/- 9 and 43.9 +/- 8 pg/ml). Left ventricular end-diastolic volume (LVEDV) and stroke volume were increased (P less than 0.001) by SL in N but not in HF. Urinary sodium excretion (UNaV) increased in N more than in HF during SL, whereas forearm vascular resistance (FVR) did not change in N and increased in HF (P less than 0.001). In five HF patients SL was performed during ANF infusion (50 ng/kg, 5 ng/kg.min) that increased ANF levels from 37.1 +/- 10 to 146 +/- 22 pg/ml. In this group, SL raised both LVEDV (P less than 0.01) and ANF (P less than 0.05), whereas FVR did not rise. In addition, the UNaV increase and renin and aldosterone suppressions by SL were more marked than those observed in HF under control conditions. Thus, in patients with dilated cardiomyopathy and mild cardiac dysfunction, plasma ANF levels are not increased by volume expansion as observed in N. The lack of ANF response is related to the impaired cardiac adaptations. The absence of an adequate increase of ANF levels may contribute to the abnormal responses of HF patients to saline load.

Adult↗
PubMed1991

Regional variations in total and nonprotein sulfhydryl compounds in the human gastric mucosa and effects of ethanol.

This study evaluated the regional distribution of sulfhydryl compounds in the human gastric mucosa and the effect of ethanol on gastric sulfhydryl tissue levels. Total sulfhydryl, glutathione, and cysteine and their oxidized forms were measured in biopsy specimens taken from the gastric body and antrum of 22 healthy volunteers. Total sulfhydryl and glutathione contents of the body of the stomach were significantly higher than those of the antrum. In contrast, cysteine concentration was higher in the gastric antrum than in the body. No difference was found in the levels of oxidized sulfhydryls between the gastric body and antrum. The effect of acute administration of ethanol on gastric sulfhydryl content was studied in nine subjects. Ethanol caused gross mucosal damage and lowered the concentration of sulfhydryl compounds in both the body and the antrum. In 10 chronic alcoholics total sulfhydryl and glutathione, but not cysteine, were markedly decreased in the gastric body but not in the antrum as compared with nonalcoholic controls. In conclusion, 1) the human gastric body contains significantly higher tissue levels of total sulfhydryls and glutathione and lower concentrations of cysteine than the antrum; 2) ethanol in a damaging concentration significantly decreases gastric tissue levels of sulfhydryl compounds; and 3) chronic ethanol intake lowers total sulfhydryl and glutathione tissue levels in the gastric body.

Adult↗
PubMed1991

Effect of biological surfaces on neutrophil O2- production and its relationship to the CD11b/CD18 integrin-dependent adherence.

The production of O2- in response to LPS, PAF, FMLP, TNF and PMA by human neutrophils in suspension and residing on surfaces coated with fetal calf serum (FCS), fibronectin (FN), laminin (LM), collagen types I and IV (CI and CIV), fibrinogen (FBG) or fibrin (FBN) was studied. Of the agonists used, PAF and LPS failed to induce a response in any of the above conditions; FMLP and PMA stimulated neutrophils to produce similar amounts of O2- either in suspension or on biological surfaces; TNF induced O2- production only by cells residing on FN, FBG and FBN. These results indicate that production of oxygen-derived free radicals by neutrophils depends on the type of agonist and the nature of the surface they interact with. The relationship between the respiratory burst and adherence was studied by measuring O2- release and adherence of neutrophils residing on FN, LM, CIV, and FBG, in the absence and in the presence of the monoclonal antibody 60.3 that recognizes the common beta-chain of CD11/CD18 integrins. FMLP, PMA and TNF increased neutrophil adherence on all these surfaces except CIV. The monoclonal antibody markedly inhibited the FMLP and PMA-induced adherence but had no effect on the O2- release elicited by these two agonists. In contrast, the monoclonal antibody inhibited both the increased adherence and O2- release induced by TNF on FN and FBG. The TNF-induced increase in adherence to LM, that was not accompanied by an increase in O2- release, was also inhibited by the monoclonal antibody. We conclude that the respiratory burst of neutrophils residing on surfaces is not necessarily correlated with adherence.

Antigens, CD↗
PubMed1991

Role of sulphydryl compounds in the defense of rat gastric epithelial cells against oxygen reactive metabolite-induced damage.

This study evaluated the role of endogenous and exogenous sulphydryl compounds in the defense of rat gastric epithelial cells against damage brought about by oxygen reactive metabolites in vitro. Toxic oxygen species were generated by xanthine oxidase in the presence of xanthine. Cell damage was assessed by 51 chromium release assay. Our data confirm that xanthine oxidase, in the presence of xanthine damages cultured rat gastric cells in a dose dependent manner (r = 0.0885, p less than 0.05). Depletion of endogenous thiols by N-ethylmaleimide significantly increases the amount of damage induced by oxygen radicals causing, at the concentration of 0.005 mM, a 60% increase in 51 chromium release (p less than 0.001). The sulphydryl agent cysteamine did not prevent cell damage induced by oxygen reactive metabolites. In conclusion, 1) depletion of endogenous thiols significantly increases the susceptibility of rat gastric epithelial cells to oxygen radical-induced damage; 2) this damage is not prevented by an exogenous agent containing a SH group.

Animals↗
PubMed1991

Sulphydryl mediation in the protection of gastric mucosal cells in tissue culture by acetaminophen.

Acetaminophen protects gastric mucosa in vivo against acute drug-induced damage and has also been shown to protect gastric epithelial cells in vitro. Protection afforded by acetaminophen in vitro is not associated with increased prostaglandin output. The present study evaluated whether protection of gastric epithelial cells by acetaminophen in vitro may be mediated by endogenous sulphydryls. Monolayers from a well-differentiated human gastric epithelial cell line were studied. Sodium taurocholate was used as a damaging agent and cell damage was assessed by the 51Cr release assay. Acetaminophen dose-dependently protected gastric cell monolayers against damage induced by sodium taurocholate. The sulphydryl blocker iodoacetamide dose-dependently decreased the concentration of nonprotein glutathione and cysteine and counteracted the protection afforded by acetaminophen. This suggests that sulphydryl compounds may mediate the protection of gastric epithelial cells by acetaminophen in vitro.

Acetaminophen↗
PubMed1991

[Anaerobic threshold in the evaluation of heart function in patients with rate-responsive pacemaker].

It is very difficult to evaluate the ability of carrying out physical exercise in patients with rate responsive (RR) pacemaker (PM). However, the anaerobic threshold (AT) proved to be a useful parameter in the evaluation of cardiac function. The AT can be easily reproduced and not influenced from emotional aspects of both the patient and the physician, moreover being under maximum and then easy to achieve. Aims of our study were: to evaluate if the cardiopulmonary stress test can represent a method to be used for a more correct rate responsive pacemaker programming; to compare the data obtained of 3 rate responsive pacemakers steered by different sensors. We have studied 24 patients, of whom 10 with Activitrax (A), 8 with Meta (M), and 6 with Phymos MPT (P) pacemakers. Patients were submitted to symptoms limited cycloergometer stress test at 2 different settings: fixed rate at 70 b/min; increasing rate at until 85% of maximum heart rate for each patient, with range 0 + 10 W/min. Gas exchange data were continuously collected using an automated system (Medical Graphic System 2001) based on Whipp and Wasserman's method.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic Threshold↗
PubMed1991

Responsiveness to phenobarbital in an adult with Crigler-Najjar disease associated with neurological involvement and skin hyperextensibility.

We present the case of a 23-yr-old man who had had since birth marked and sustained unconjugated non-hemolytic hyperbilirubinemia and who had had several attacks of grand mal seizures. Analysis of serum bilirubin by diazoreactive methods showed serum levels of unconjugated bilirubin as high as 445 mumol/L that were not affected by phenobarbital administration. However, analysis of serum bile pigments by high-pressure liquid chromatography demonstrated marked decrease of unconjugated bilirubin after phenobarbital treatment (from 432.4 mumol/L to 291.0 mumol/L) associated with slight increase of bilirubin monoconjugates and disconjugates (from 0.25 mumol/L to 0.42 mumol/L). Furthermore, in the past few years the patient had exhibited striking skin hyperextensibility and diaphragm eventration. This case confirms that alkaline methanolysis-high-pressure liquid chromatography is the most reliable method for assessment of serum fraction bilirubin levels; that clinical parameters such as neurological signs do not unequivocally discriminate between type I and II Crigler-Najjar disease and that response to phenobarbital treatment remains the main diagnostic tool.

Adult↗
PubMed1991

Abnormal recovery systolic blood pressure response for detecting coronary artery disease in men and women investigated by upright bicycle exercise.

We investigated the clinical significance of recovery systolic blood pressure (SBP) ratio, obtained dividing the recovery SBP at 1st (R1/A) or 3rd min (R3/A) by the peak exercise SBP (before stopping), during upright bicycle exercise in 530 subjects (ranging from 17 to 73 years). Our results may be summarized as follows: 1) we found a higher value of R1/A in control subjects with exercise induced ST depression; 2) the normal range in women was higher than in men; 3) the use of recovery SBP ratios gives a lower sensitivity and a higher specificity than ST segment analysis in detection of CAD; 4) this pattern may be useful particularly in patients with previous myocardial infarction and not detectable ST segment analysis during exercise.

Adolescent↗
PubMed1990

[Surgical mitral valvuloplasty in the treatment of mitral valve diseases].

Mitral valve repair surgery, in presence of a pure mitral leakage or one associated to a stenosis, is not only possible but has been well codified for a decade. According to damage, there are two methods of operation: valvular mobilization surgery and valvular motion amplitude reduction surgery. They are usually associated to annuloplasty with a Carpentier prosthetic ring. The incidence of late mortality is of 0.6 p. 100 pt/yr, that is to say 91.7 p. 100 at 13 years. This late survival rate is about 20 p. 100 better than for a valvular replacement. Reoperations rate is 1.6 p. 100 pt/yr. The incidence of thromboembolic event occurrence is low: 0.5 p. 100 pt/yr. The ideal indications for mitral valve repair are represented by damage of prolapse from a degenerative origin for which results are better and more constant. For rheumatic damage, the valvular repair indication depend on the valvular tissue elasticity and area. The presence of calcification and extensive fibrosis remain on principle counter-indications.

Adult↗