Biomedical subjects

M De Meo

Publications and source records attributed to M De Meo.

22 records · Page 2Linked to original sources

PubMed1978

Use of high-pressure liquid chromatography to determine plasma levels of metronidazole and metabolites after intravenous administration.

A rapid and sensitive high-pressure liquid chromatography assay for metronidazole and its two principle metabolites, 1-(2-hydroxyethyl-2-hydroxymethyl)-5-nitro-imidazole [hydroxy metabolite] and 1-acetic acid-2-methyl-5-metronidazole [acid metabolite], was developed. The retention times observed were 5.7, 3.3, and 4.5 min, respectively. A reverse-phase muC(18) Bondapak column using a solvent system of methanol, acetonitrile, and 0.005 M pH 4 potassium dihydrogen phosphate (4:3:93, vol/vol) was used to achieve separation of the three compounds. Patients receiving metronidazole therapy were given a loading dose of 13.6 mg of drug per kg intravenously over 1 h, followed by a maintenance dose of 1.43 mg/kg per h. The range of metronidazole concentrations observed was 6.8 to 47.5 mug/ml. These levels are well above the minimal inhibitory concentrations of most clinically significant anaerobic bacteria including Bacteroides fragilis. Little of the acid metabolite was observed in the plasma. The concentration of hydroxy metabolite ranged from 1.6 to 16 mug/ml. The latter may represent an additional source of antimicrobial activity since the hydroxy metabolite has approximately 30% the biological activity of metronidazole.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Procedures for destruction of patulin in laboratory wastes.

Patulin is immunosuppressive and there is limited evidence of its carcinogenicity in experimental animals. The International Agency for Research on Cancer (IARC) initiated a programme for the development of degradation techniques for the commonly investigated mycotoxins. As a part of this programme, the following techniques were tested for the degradation of patulin: treatment with ammonia, treatment with ascorbic acid, and treatment with potassium permanganate in acidic or in alkaline conditions. Patulin analysis was performed by using HPLC with UV detection. Mutagenic activity of degradation residues was tested by in Salmonella typhimurium strains TA 97a, TA 98, TA 100, and TA 102. Complete disappearance of patulin was not achieved after 92 h of treatment with ascorbic acid. All the other methods tested led to complete removal of the molecule. However, the technique using potassium permanganate in acidic conditions produced residues which were mutagenic without activation to Salmonella typhimurium strains TA 100 and TA 102, which was attributed later to Mn2+. The two other techniques gave satisfactory results and were selected for further validation studies.

Ammonia↗

PubMedDate not supplied

Luteinizing hormone pulsatility is altered in essential hypertension.

The aim of this investigation was to study the pattern of luteinizing hormone (LH) secretion in men with mild and moderate hypertension. LH pulsatility was evaluated for 8 h in 14 male patients, subdivided into 2 groups; group A, consisting of 8 patients, whose systolic blood pressure ranged between 180 and 160 mm Hg and whose diastolic blood pressure was between 115 and 105 mm Hg; and group B, 6 patients whose systolic blood pressure ranged between 220 and 180 mm Hg and whose diastolic blood pressure was between 104 and 95 mm Hg. Seven healthy males were evaluated as controls (group C). The major changes of LH pulsatility in group A included an increased peak width, increased peak amplitude, and increased peak area. In group B the changes followed the same pattern as in group A, but were more pronounced. The number of LH peaks was reduced, the peak width was increased, and both peak amplitude and peak area were increased as compared to the control group. The pattern of LH pulsatility is altered in essential hypertension and the main feature is represented by the prolonged duration of LH peaks and their greater amplitude. The altered pattern of LH secretion is likely to reflect a primary hypothalamic derangement with the gonadotropin releasing hormone (Gn-RH) secreting neurons remaining synchronized for longer times and secreting larger Gn-RH masses than in normal subjects. Since the nuclei of the brain stem (A1-A6) involved in the control of Gn-RH secretion respond to blood pressure changes, the altered activity of monoaminergic neurons may be the link between hypertension and changes of LH pulsatility.

Adult↗

PubMedDate not supplied

Flow cytometry to evaluate the parasitemia of Plasmodium falciparum.

The resistance of plasmodiums to the current antimalarial agents has spurred the search for new active molecules of vegetal origin or chemical synthesis. The screening of antimalarial molecules "in vitro" was done by simple but tedious techniques such as quantification of parasitemia through optical microscopy or by using radioactive markers. We have developed a new method to evaluate parasitemia by using the ODAM ATC 3000 flow cytometer and biological cell sorter. We selected the ethidium bromide for labelling the nucleic acids of Plasmodium falciparum, and we optimised the method by using a mathematical model: the design of Hadamar. This simple technique presents the advantage of being an objective and rapid count of large number of red cells (10(6) x 10(7)). This method is rapid, reliable, reproducible, devoid of subjectivity and provides more precise results than those of optical microscopy. The good correlation between paraitemia measured by optical microscopy and fluorescence obtained by flow cytometry allows us to recommend this technic for the screening of new antimalarial molecules.

Ethidium↗