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Biomedical subjects

C Manso

Publications and source records attributed to C Manso.

At least 19 recordsLinked to original sources
PubMed1992

[Angiotensin-converting enzyme inhibitors as neutralizers of hydroxyl radical].

Angiotensin converting enzyme inhibitors are utilized in the treatment of essential hypertension and of chronic cardiac failure. They are also employed in the treatment of the myocardial lesion of ischemia-reperfusion, which involves oxygen free radicals. In the present study we investigated the possibility of three angiotensin converting enzyme inhibitors (captopril, enalapril, lisinopril) to act as hydroxyl radical scavengers. The rate constants for reactions of those compounds with .OH were determined using the deoxyribose method. All there compounds proved to be good scavengers of .OH with rate constants of about 10(10)M-1s-1 and are iron chelators specially enalapril. The fact that captopril possesses a thiol group does not confer an higher antioxidative capacity. These results suggest that scavenging of oxygen free radicals may be a possible mechanism contributing to the therapeutic effect of angiotensin converting enzyme inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

[Aging and free radicals].

Several theories on aging are presented. All of them give important contributions but none explains all the aspects of the problem. Oxygen radicals produced during cellular combustion contribute to aging through multiple cumulative microlesions throughout life. The importance of glucose is emphasized; it forms early and late Maillard compounds. Other causes of aging are discussed.

Aging↗
PubMed1991

Plasma catecholamines and postural hypotension in familial amyloidotic polyneuropathy of the Portuguese type.

Plasma adrenaline and noradrenaline levels were measured while supine and following head-up tilt to 45 degrees, in both normal controls and in patients with familial amyloidotic polyneuropathy of the Portuguese type. In nine patients systolic blood pressure fell by less than 15 mmHg, while in seven patients it fell by more than 15 mmHg. Plasma noradrenaline rose during tilt in the majority of patients, as in the controls. There was no correlation between levels of catecholamines and fall in blood pressure on head-up tilt. The data excludes widespread sympatho-neural failure as a cause for postural hypotension in familial amyloidotic polyneuropathy of the Portuguese type. The results are compatible with either segmental/patchy sympathetic denervation or dysfunction of the receptor/effector mechanisms in target organs such as the heart and blood vessels.

Adult↗
PubMed1991

[Determination of endoxin in hypertensive patients].

Digoxin like immunoreactive factor (DLIF), has been implicated on the effect of sodium in essential hypertension. The different concentration of DLIF as a function of sodium intake was demonstrated in animal experience by some authors. In this work the urinary DLIF excretion is evaluated by RIA and its biological activity by Na+/K+ ATPase inhibition, in 5 urine samples at the end of a free sodium diet week and in 10 urine samples in the last day of a week with 250 mg sodium diet. The urinary DLIF excretion after the free sodium diet week was 0.3460 +/- 0.055 and at the end of sodium restriction diet week of 0.2910 +/- 0.061 nmol/l. Although the DLIF values in the sodium restriction week were smaller than the DLIF values of the free sodium diet week, there was no statistical difference (p = 0.113). In five patients the DLIF could be evaluated at the end of the first and second weeks without changes in the hypertensive therapeutics, with clonidine and nifedipine, along the two weeks. In these five patients at the end of the free sodium diet week and at end of the sodium restricted diet week were 0.3460 +/- 0.055 and 0.2780 +/- 0.060 nmol/l. The reduction of urinary DLIF excretion in the sodium restricted diet week, was significative (p = 0.020). The results of the Na/K ATPase inhibition in the same five patients were: 34.6 +/- 6.51% at the end of the free sodium diet week and 31.7 +/- 6.32% at the end of the sodium restricted diet week, the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Relaxing and constricting factors derived from vascular endothelium].

The Author summarizes the factors produced in vascular endothelium in response to different stimuli. The relaxing factor is identified as nitric oxide, a radical, whereas the constricting factor, endothelin, is a peptide. Their actions are related to several situations, both normal and pathologic, still poorly understood.

Endothelins↗
PubMed1991

[Lipoproteins].

The problem of plasma lipid transport between several organs is reviewed. The constitution of plasma lipoproteins is described as well as the importance of enzymes related to them. The problem of lipid transfer proteins is discussed. The origin of atherosclerosis is analyzed in relation to abnormalities of cholesterol metabolism, of its transport and of free radicals generation.

Adipose Tissue↗
PubMed1990

[Lipoproteins, free radicals and atherosclerosis].

The Author reviews vascular, lipidic and oxidative factors in the genesis of atherosclerosis. He admits the possibility that an alteration in the arterial wall, an increase in circulating lipids or an oxidative stress may influence the precocity of atherosclerosis. The transport of lipoperoxides or of oxidized cholesterol by lipoproteins renders them toxic and susceptible to aggravate atherosclerosis.

Animals↗
PubMed1989

Decreased plasma benzylamine oxidase in a subgroup of schizophrenia.

Plasma benzylamine oxidase (BzAO) activity was analysed in a group of 40 schizophrenic patients and compared with that of healthy controls. Although plasma BzAO was significantly decreased in schizophrenics as a whole, when patients were divided into type I (favourable course) and type II (poor course) it was found that the reduced BzAO activity was only observed in type I. Several clinical features were associated with a low BzAO level. The clinical and biological significance of the identification of a biochemical alteration in a subgroup of schizophrenic patients is discussed, and we suggest that the possibility of BzAO being a marker for prognosis in schizophrenia should be further investigated.

Adolescent↗
PubMed1989

[Oxygen radicals and hypertension].

The Author reviews the problem, starting with a short introduction about oxygen free radicals. He discusses the vascular factor, emphasizing the importance of several known relaxants, EDRF, prostacyclin, monooxigenated arachidonate derivatives, ANF, hydrogen peroxide and hydroxyl radical. He analyses the involvement of free radicals in kidney damage and presents evidence for their formation during cerebral vascular accidents.

Arachidonic Acid↗
PubMed1988

Mechanisms of hemolysis induced by copper.

An excess of copper is the cause of hemolysis in a number of clinical conditions. Incubation of human erythrocyte (RBC) suspensions with copper (II) causes the formation of methemoglobin, lipid peroxidation and hemolysis. A new variant of the thiobarbituric acid (TBA) method, which minimizes the formation of interfering chromophores, was used to detect lipid peroxidation. Lipid peroxidation precedes hemolysis and the antioxidant vitamins C and E, which inhibit lipid peroxidation, also inhibit hemolysis. Consequently lipid peroxidation appears to be the cause of RBC destruction. Lipid peroxidation arises mostly from the oxidation of oxyhemoglobin by copper as it is inhibited in RBCs with carbon monoxyhemoglobin or methemoglobin. A direct interaction of copper with the red cell membrane seems to play only a minor role. Copper effects depend on the presence of free SH groups. Lipid peroxidation is probably initiated by activated forms of oxygen as it is increased by an inhibitor of catalase and reduced by hydroxyl radical scavengers. With higher copper concentrations hemolysis is greater: its mechanism appears different as lipid peroxidation is smaller but hemoglobin alterations, namely precipitation, are more pronounced.

Ascorbic Acid↗
PubMed1988

Superoxide radical generation by Amadori compounds.

Several D-sugars were incubated with L-lysine or with L-arginine for 10 days. The resulting compounds are able to reduce nitrobluetetrazolium (NBT). This is prevented by superoxide dismutase (SOD), indicating that the superoxide radical is generated by the resulting Amadori compounds. The formation of superoxide radical in vivo, as a result of nonenzymatic glycosylation of proteins, may be considered to be a contributory factor to the appearance of chronic complications of diabetes.

Carbohydrate Metabolism↗
PubMed1987

Mannose inhibition as a significant marker for differentiating among novobiocin-resistant staphylococci of relevance in clinical microbiology.

A specific method for the identification of Staphylococcus saprophyticus among novobiocin-resistant species isolated from man is described. The test is based on novobiocin resistance, non-fermentation of D-mannose and early inhibition with late secondary growth on glucose/mannose + novobiocin agar plates. On this medium novobiocin-resistant Staphylococcus cohnii showed a confluent, continuous and homogeneous growth after 24 h which remained unchanged at 48 h whether or not it fermented D-mannose, whereas novobiocin-resistant Staphylococcus xylosus fermented D-mannose. These results are discussed in relation to a possible causal role of PTS enzymes and phosphomannose isomerase deficiency in mannose inhibition.

Drug Resistance, Microbial↗
PubMed1987

The neutralization of hydroxyl radical by silibin, sorbinil and bendazac.

The compounds silibin, sorbinil and bendazac act as hydroxyl radical scavengers, when the hydroxyl radical is generated by the Fenton reaction. Hydroxyl was detected by the degradation of deoxyribose. The Authors discuss the possibility that the scavenger activities of those compounds may explain, at least in part, their therapeutic activity.

Antioxidants↗
PubMed1986

Putative reverse transcriptase intermediates of human hepatitis B virus in primary liver carcinomas.

Nucleocapsid-pol fusion proteins have been detected by serological screening hepatocellular carcinoma tissues that contain hepatitis B virus (HBV) DNA. The existence of these fusion proteins suggests that HBV may synthesize its reverse transcriptase in a fashion analogous to the way that retroviruses synthesize and process a precursor. The accumulation of HBV reverse transcriptase intermediates in tumorous tissues and not in other tissues may be related to the absence of viral core particles and possibly contributes to tumor development.

Animals↗
PubMed1985

Inhibitory effect of drugs used in the treatment of Parkinson's disease on plasma monoamine oxidase activity.

The plasma amine oxidase (benzylamine oxidase, BzAO) of patients with Parkinson's disease is sometimes decreased in activity, when compared to normal controls. This is the result of therapy with DOPA decarboxylase inhibitors. The Authors suggest that complications due to prolonged therapy with these drugs may be, at least in part, the result of an interference with BzAO capacity to catabolize circulating amines.

Adult↗