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M Melegari

Publications and source records attributed to M Melegari.

54 records · Page 3Linked to original sources
PubMed1982

[Structure-activity relationships in N1-acetylderivatives of sulpha drugs].

The N1-acetylderivatives (ASA) of sulphanylamides (SA) were prepared and their stability to hydrolysis was evaluated together with the spectroscopic and antibacteric activity parameters, with the aim both of obtaining electronic structure-activity relationships and of comparing these results with those previously found for SA. From our results it appears that: a) the stability to hydrolysis is dramatically reduced on passing from the aqueous medium (pH 7) to the culture broth, and that b) in general, the ASA examined do not show any greater antibacterial activity with respect to the parent compounds, as suggested by the values of the spectroscopic indices-taken as experimental electronic indices. This result is in full agreement with the structure-activity relationships previously proposed fo the sulpha drugs.

Bacteria↗
PubMed1978

Electronic aspects of the antibacterial action of sulfanilamides.

Intramolecular interactions in N1-substituted sulfanilamides (SA) can rationalize the trend of their antibacterial powers with the use of a resonance scheme, derived from d orbital symmetry and tested with an extensive spectroscopic investigation on amidic, imidic, and anionic SA. On quantitative grounds, a good relationship is presented between the antibacterial power and the proton chemical shift of the p-amino group. The electronic features for high activity are described.

Bacteria↗
PubMed1976

Preparation and spectroscopic behavior of acetylderivatives of sulphonamides.

Acetylderivatives of five sulpha drugs (N1-phenylsulphamilamide, sulphapyridine, sulphapyrimidine, sulphamerazine, sulphamethazine) and of three reference compounds, devoid of the para amino group, are synthetized. The trends of the U.V. spectra and of the symmetric stretching frequency of the SO2 group of the prepared compounds are described and discussed in a systematic way, by means of a simple conjugation model. Our data show that, on the basis of the values of the indices of electronic structure [upsilons(SO2), lambdap], the N1-acetylderivatives would appear to have a lower bacteriostatic activity than that of the non-acetylated compounds, which is in disagreement with the literature. The question therefore arises as to whether the N1-acetylderivatives are to be considered an exception to the structure-activity correlations previously put forward, or whether, owing to phenomena of hydrolysis, the degree of activity can no longer be attributed to the form characterized by the indices measured.

Acetylation↗
PubMedDate not supplied

Ethanol-induced increase in cytosolic estrogen receptors in human male liver: a possible explanation for biochemical feminization in chronic liver disease due to alcohol.

The hepatic cytosolic estrogen receptor content was measured in liver samples from patients with normal livers and from patients with nonalcoholic cirrhosis, alcoholic cirrhosis and alcoholic hepatitis. The estrogen receptor content of normal liver was 5.2 +/- 3.5 fmoles per mg of cytosolic protein. Levels which were not significantly different from this were found in the samples from patients with nonalcoholic cirrhosis (2.1 +/- 2.0 fmoles per mg of cytosolic protein). The cytosolic estrogen receptor content in the livers of patients with alcoholic cirrhosis who were abstaining was 4.2 +/- 3.6 fmoles per mg of cytosolic protein, but it increased to 10.4 +/- 4.9 fmoles per mg of protein in the livers of patients with alcoholic cirrhosis who were drinking, to 17.3 +/- 8.7 fmoles per mg of protein in the livers of patients with alcoholic hepatitis with cirrhosis and to 22.7 +/- 15.7 fmoles per mg of protein in the livers of patients with alcoholic hepatitis without cirrhosis. Alcohol abuse appeared, therefore, to induce an increase in the estrogen receptor content of human liver, especially in patients who were drinking and had histological evidence of acute liver damage (alcoholic hepatitis). The increase in hepatic estrogen receptor which we have observed may be involved in the molecular mechanisms underlying the feminization of the liver in alcoholic males.

Aged↗
PubMedDate not supplied

Hepatocellular carcinoma: risk factors other than HBV.

The putative risk factors for hepatocellular carcinoma (HCC) are several, even in countries endemic for hepatitis B virus (HBV) infection. Cirrhosis characterizes more than 90% of HCC cases. The phases of inflammation, necrosis and regeneration, present for long periods in cirrhosis, might be most relevant in hepatocarcinogenesis. It is not clear what role is played by sex hormones while alcohol probably has a promoter role. Aflatoxins are known carcinogenins in the experimental animal: however it is difficult to evaluate the impact in human carcinogenesis due to the lack of reliable methods of measuring aflatoxin exposure in population studies. In conclusion, the aetiology of HCC is multifactorial and the main risk factor resides in the presence of underlying chronic liver disease.

Aflatoxins↗
PubMedDate not supplied

[Estrogen receptors in the human liver].

Human hepatic estrogen receptors (ER) were investigated in 17 healthy subjects (13 males and 4 females) and 70 patients with chronic liver disease (45 males and 25 females). Characterization of the estrogen binders in cytosol from human male liver showed two classes of binders, the first of them corresponding to estrogen receptor (Kd = 10(-10) M), and the second representing a low affinity binder (KD = 10(-8) M). Increased ER levels were found in males with chronic liver disease, patients with primary hepatic carcinoma (PHC) having about twice the levels of normal males. Normal females had basal values about three times higher than control males; during the progression of chronic liver disease, ER levels fell to arise again slowly so that, in PHC, values were about half of those in normal females. Prolonged alcohol abuse appeared to induce a marked increase in ER levels both in male and in female patients. The increase was maximal in patients who were still actively drinking and in those with histological signs of acute alcoholic hepatitis.

Carcinoma, Hepatocellular↗
PubMedDate not supplied

[HBV DNA in mononuclear cells of peripheral blood in acute hepatitis B: a comparative analysis of Southern blot and polymerase chain reaction (PCR)].

Hepatitis B virus (HBV) infection of peripheral blood mononuclear cells (PBMCs) has been observed in all stages of liver disease. The data available on acute hepatitis patients are limited. We therefore focused our attention on the presence of HBV DNA sequences in PMBCs of 30 patients with acute type B hepatitis. Southern Blot analysis showed no HBV sequences in PMBCs, although the sensitivity of our method enabled us to detect as low as 1 pg of cloned HBV insert. On the other hand, Polymerase Chain Reaction (PCR) demonstrated the presence of HBV related sequences in 14 out of 30 patients (5 HBeAg positive, 9 anti HBeAg positive). Our results indicate that the involvement of PMBCs with HBV during acute infection is not correlated with viral replication and occurs at a very low level, so that its detection by traditional Southern Blotting can prove ineffective.

Acute Disease↗