Biomedical subjects
Publications and source records attributed to M Georgescu.
In a scanning electron microscope study evaluating the effects of a 10% carbamide peroxide gel on stained enamel and dentin, no surface morphologic changes were observed after 72 hours of contact with the bleaching gel.
Oxidative modification of genetic material has been implicated as a factor in carcinogenesis, particularly during promotion and progression, and therefore there is a need for sensitive detection of oxidized DNA bases. We developed a method that can be applied to DNA isolated from any source and used to simultaneously quantify oxidized nucleosides without a need to prelabel the DNA or use destructive hydrolytic procedures. This method is based on: (a) enzymatic DNA digestion; (b) HPLC separation of the resultant nucleosides; (c) acetylation of the oxidized nucleosides with [3H]Ac2O (acetic anhydride); (d) removal of the radioactive debris; and (e) quantitative analysis of tritiated nucleoside acetates by HPLC. Enzymatic DNA digestion was optimized using DNase I in the presence of Mg2+ (pH 7), followed by nuclease P1 in the presence of Zn2+ (pH 5.1) and alkaline phosphatase (pH 7.5). Analysis of DNA oxidized with H2O2 in the presence of Fe2+/EDTA for 30 min showed that the levels of 8-OHdG (8-hydroxy-2'-deoxyguanosine) were increased 2.7-fold, HMdU (5-hydroxymethyl-2'-deoxyuridine) 3.15-fold, and FdU (5-formyl-2'-deoxyuridine) 2.5-fold. Although the (-)-isomer of cis-dTG (cis-thymidine glycol) was enhanced 2.3 times, the (+)-isomer remained virtually unchanged. Analysis of DNA isolated from epidermal cells of mice treated in vivo with the tumor promoter TPA (12-O-tetradecanoylphorbol 13-acetate) showed 4.8-, 2.7-, and 8.7-fold increases in the levels of total cis-dTG, 8-OHdG, and HMdU, respectively, and of some unknown DNA oxidation products. These results prove applicability of the 3H-postlabeling method to the analysis of DNA (and potentially RNA) isolated from many sources, including animals and humans.
Using a two stages screening method the prevalence in the general population of hyperlipoproteinemias (HLP), separated in the five types proposed by Fredrickson, Levy and Lees, and adopted by WHO has been studied. The study included 7,085 subjects of both sexes, aged 25-65 years, representing 84,52 % of a population taken at random within a district of Bucarest. HLP was found in 1,013 cases, i.e. 14,29 % of the investigated population. 48.37 % were men and 51.63 % women. The prevalence of HLP was lowest in the first decace of age studied (25-35 years) and highest in the last two decades (45-65 years). Overweight was more frequently encountered in these patients (64.46 %) than in the total population (32.3 %). Of the 1,013 cases with HLP, 42.35 % (6.05 % of the total population) were of type IV, 27.05 % (3.86 % of the total population) of type II-b, 22.80 % (3.26 % of the total population) of type II-a, 4.74 % (0.67 % of the total population) of the type III and 3.06 % (0.43 % of the total population) of the type V. 22.70 % of the HLP patients were considered primary familial HLP, 66.54 % primary non-familial HLP and 10.76 % secondary HLP; IN 109 secondary HLP, the most frequently encountered disease was diabetes mellitus (42.20 %), followed by hypothyroidism (24.77 %), alcoholism (12.84 %), obstructive liver diseases (9.17 %), pancreatitis (5.50 %), nephrotic syndrome (2.75 %) and treatment with estrogens and steroids (2.75 %).
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Transversal epidemiologic investigations carried out in different populations from several regions of Romania : Gurghiu Valley (lumberjacks from a mountain region), Danube Delta and Razelm lagoon complex (fishermen), and Bucharest have shown that, in spite of the high caloric value of food and even of a high intake of saturated fats, mean serum cholesterol is lower in the rural areas than in Bucharest, probably owing to the strenuous physical work. However, except myocardial infarction, more frequent in the urban than in the rural regions, the other forms of coronary heart disease have a relatively higher frequency in villages, particularly atrial fibrillation and ECG signs of ischemia. These findings might be explained by a greater prevalence of hypertension in these populations. It is concluded that the risk factors, which act synergically, depend on the complex structure of the "ecologic niche".
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Four patients with infantile familial sudanophilic leucodystrophy confirmed histologically and biochemically were investigated by E.E.G. and E.M.G. The E.E.G. showed a severe, non-specific slow wave abnormality, of moderate voltage and disorganized in 2 cases, with some critical' tonic' discharge. E.M.G. study was normal in relaxed muscle; peripheral nerve stimulation, however, revealed marked slowing of motor conduction velocities favouring a segmental demyelinisation process, which was ultimately confirmed histologically. This study underlines the value of investigation of infantile encephalopathies.
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Immunoglobulins G (IgG) were determined in the neonate using immunodiffusion in Hyland Travenol agar gel. IgG values were tested in the umbilical cord and perpheral blood, establishing their relationship with various parameters. Hypogammaglobulinemia does not appear to be so rare in the neonate (4.91%).
Intradermoreaction with toxoplasmin in apparently healthy subjects gave positive reactions in 13% of the cases. The mothers of children with neuropsychical diseases and congenital malformations were positive to toxoplasmin in 62-63% of the cases and with the Sabin-Feldman reaction in 9.6-13.8%. High proportions of positive results. (29.1-30%) were obtained with both tests in the children with neuropsychical diseases and congenital malformations. Host-parasite relationships in the early period of embryonic development deeply affects the normal evolution of the embryo and foetus. The individual structural level of the epidemiologic human toxoplasmosis process is conditioned by the moment at which the host-parasite relationships are established.
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To extend previous observations on the quantitative changes of IgA and other serum Ig in diabetics, additional immunochemical investigations were carried out in 96 patients, 63 males and 33 females, mean age 43.5 +/- 15.7 years, 51 with type 1 (insulin-dependent) and 45 with type 2 (non-insulin-dependent) diabetes. The immunological data were correlated with the clinical-metabolic aspects. In the whole group, the IgA level was increased (144.1 +/- 57.2 I.U.). Significant differences were recorded with respect to age for IgG, to age and diabetes type for IgA, to sex for IgM. Qualitative Ig changes, reflecting disturbances of molecular structure, mainly for IgG, seldom for IgM, but never for IgA, were observed in 20% of the patients with both types of diabetes, more seldom in cases with long disease duration. The IgG with qualitative changes were purified and their functional capacity of inhibiting the natural cytotoxic activity (NK) was tested in comparison with that induced by pretreatment of the effectory cells with normal IgG. Some of these modified IgG showed a reduced capacity of inhibiting the NK activity. These data confirm the existence of certain quantitative changes of the main serum Ig in diabetics and reveal the presence of qualitative disorders of the IgG molecules, with consequences on their functionality.
The drug resistance of 1,860 human mycobacterial strains was analysed. Of these 987 were isolated from new cases and 873 from cases who underwent a treatment for pulmonary tuberculosis. The investigation lowered 3 years (1986-1988). It resulted that the frequency of primary resistance was of 23.8% and that of secondary resistance was of 47.6%. As part of primary and secondary resistance, mono-resistance to SN and bi-resistance to SN and INH were the most common.
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A new method of long term, retrospective evaluation of the lipid metabolism balance, by cholesterol and lipid assays in the human hair, is described. The correlation index between the blood and the hair cholesterol and lipid concentrations was + 0.980 and + 0.9925, respectively. The effects of hypolipemic diet and drug therapy on the cholesterol and lipid values were studied comparatively in the blood and in successive hair segments. The results demonstrate that the new method permits an evaluation of the therapy effectiveness and of the lipid metabolism variations during several weeks or months.
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The authors have studied the value of culture media based on pyruvic acid (the Dixon medium and an original medium called P.T.) in the isolation of mycobacteria from sputum, as compared with the Löwenstein-Jensen medium. The studies were carried out in two groups of patients: 1043 samples were collected from ambulatory patients and 1740 samples were collected from hospitalized patients. The superiority of the Dixon and of the P.T. media was confirmed by the increased percentage of positive cultures (11% and 20% respectively) as compared with the Löwenstein-Jensen medium. With these media it was possible to isolate mycobacteria 7--14 days earlier than with the other media. On the basis of the results obtained the authors recommend the use, in parallel, especially in those cases when the samples contain only a small number of bacteria, of the Löwenstein-Jensen medium and one of the media based on pyruvic acid.