The hydrazine derivative aminoguanidine inhibits the reaction of tetrahydrofolic acid with hydroxymethylarginine biomolecule

Aminoguanidine (AG), a hydrazine derivative is known to inhibit the formation of Advanced Glycosylation Endproducts (AGE) and AG has been proposed as an agent in prophylaxis of diabetic complications. However, treatment with hydrazine produced liver and lung tumors by formation of N7- and O6-methylguanine in the DNA of rodents. The hydrazine derivative, isonicotinic acid hydrazide induced pulmonary tumors in mice. N(G)-hydroxymethyl-arginine (HMA) was synthesized by our research group and it showed anticancer effect against experimental tumors. HMA was found earlier in human blood and urine, and recently in many plants (in fruits and vegetables). We could demonstrate a reaction (pH = 7.5, 37 degrees C, 1h) between HMA and tetrahydrofolate (THF) producing N5,N10-methylene-tetrahydrofolate (CH2-THF), the coenzyme of thymidylate synthase (TS). In model experiments AG proved to react with formaldehyde (HCHO) and to eliminate the C1-fragment of HMA, but not that of CH2-THF. In the presence of AG burst chemiluminescence and a higher speed of the formylation and methylation reactions were found in the AG, HCHO, hydrogen peroxide (H2O2) and L-lysine system than without AG.

CONCLUSIONS

HMA as a biomolecule is one of the compounds which are responsible for the endogenous HCHO level. The biochemical function of HMA may be the direct supply of C1-fragment for the folate cycle. AG can disturb the above function of HMA. The reaction between AG and HCHO seems to be dangerous for biological systems because of the possible presence of L-lysine and H2O2. The burst chemiluminescence indicates excited molecules with extreme high energy producing uncontrolled formylation and methylation reactions. Considering the results of the experiments with AG its use as a medicament seems to be questionable.

Determination of endogenous formaldehyde in plants (fruits) bound to L-arginine and its relation to the folate cycle, photosynthesis and apoptosis

A very powerful nucleophilic reagent, hydralazine(1-hydrazino-phtalazine) proved to be suitable for determination of the endogenous formaldehyde level in biological samples. It was found that in different plants (vegetables, fruits, especially in red beet, cauliflower, kohlrabi, grapes) is a large amount of releasable endogenous formaldehyde (0.5-1.0 mM) bound to L-arginine mainly in the form of N(G)-trihydroxymethyl-L-arginine (TriHMA). N(G)-hydroxymethyl-L-arginines (HMA) were proved to transfer their hydroxymethyl groups to tetrahydrofolic acid producing N5,N10-methylene-tetrahydrofolate, the coenzyme of thymidylate synthase. HMA was found to inhibit the cell proliferation of HT-29 cell culture (human colon adenocarcinoma ATCC HT-B 38) causing apoptosis. Photosynthetic experiments produced confirmatory evidences that 14CH2O could be formed in photosynthesis already after 10 seconds of 14CO2 fixation in the seedlings of Zea mays L. (single cross) and the 14CH2O was immediately trapped by L-arginine mainly as TriHMA.

Analogies and differences in the excited reactions of formaldehyde and D-glucose

The investigations proved that D-glucose (as reducing sugar) can easily be activated in a ternary system (L-lysine: D-glucose: H2O2) similarly to formaldehyde at 20 degrees C, in pH = 7.4 forming chemiluminescence (CL) and singlet oxygen. The kinetic investigation showed that: CL lasted many hours (permanent emission) and had no bell-shaped curve differently from other aldehydes e.g. formaldehyde. The reason of the effect is that D-glucose exists mainly in ring form in water solution (Haworth ring form) and the open form (the aldehyde group) is slowly liberated during the excited reaction. These excited reactions may be important in human organism, because D-glucose and lysyl residues of proteins occur permanently in human body and endogenous formaldehyde and H2O2 may be liberated there, too.

[Tricho-odonto-onycho-syndrome in hyphydrotic form based on two cases]

Authors demonstrate the hypohydrotic form of the tricho-odontoonycho syndrome by a 13 years old sister and by a 12 years old brother. It is given a review of the literature of this and similar other syndromes.

[Incidence of structural disorders of teeth in hereditary epidermolysis bullosa]

Authors present a 12-year old boy, whose diagnosis was epidermolysis bullosa. Beside the general characteristics of the illness they discuss the dental status of the patient and sum up the literary references together with other anomalies occurring in epidermolysis bullosa hereditaria.

[Scanning electron microscopy of the resorption surface of deciduous teeth]

Based on a study of ten deciduous human teeth, (front teeth and molars) under a Scanning Electron Microscope type Tesla BS 300 we could observe that the differences of the mineralization levels are more striking in the peritubular dentin, then in the intertubular structures. The structural transformation increases by approaching the resorption surface. Near the enamel the resorption surface shows a two-edged demineralization. The mineralized part near the enamel is probably the result of the protecting processes of the human organism.

[Clinico-pharmacologic studies on pefloxacin]

The impact of liver impairment, renal insufficiency and age-related changes on the pharmacokinetics of pefloxacin was studied in 55 patients. The elderly patients were stratified into three age groups (61-70, 71-80 and above 81 years). The patients suffering from various infections were treated with oral or intravenous pefloxacin in a dose of 400 mg bid. Blood samples were withdrawn on the first and seventh day of therapy. The pharmacokinetics of pefloxacin was characterized by marked interindividual differences that became even more pronounced during multiple dosing. The elimination rate of pefloxacin during therapy slowed down, presumably due to its decreased metabolism. In elderly patients, the rate of cumulation is greater than in the young ones, but no significant differences could be detected among the elderly age-groups. Pefloxacin elimination also decreased in renal and hepatic impairment. There was no correlation between serum concentrations of pefloxacin and the development of adverse effects. In elderly subjects and in patients with renal or hepatic impairment, dose reduction might be considered. In mild or moderate infections or in urinary tract infections smaller doses of pefloxacin also could assure good therapeutic results. However, in severe infections especially caused by less susceptible pathogens, routine dose reduction is not recommended because of the significant interindividual differences in serum concentrations of pefloxacin.

Metabolic interactions of ciprofloxacin

The mechanism and clinical relevance of the inhibitory effect of ciprofloxacin on the metabolism of selected drugs were studied in patients with bacterial infections. In study A, antipyrine tests were carried out in two groups of patients taking 1000 mg (group 1) and 250 mg (group 2) of oral ciprofloxacin for 7-10 days. Antipyrine was given intravenously in a dose of 15 mg/kg body weight before and after ciprofloxacin treatment. Blood samples were taken at 0, 2, 4, 6, and 10 hr after dosing. In group 1, ciprofloxacin administration resulted in a significant decrease in antipyrine elimination (t1/2, 9.45 +/- 3.74 vs. 14.92 +/- 3.32 hr). The average decrease in antipyrine clearance was 35% (0.85 +/- 0.45 vs. 0.52 +/- 0.24 ml/min/kg). In group 2, the change in antipyrine kinetics was less pronounced (t1/2, 9.79 +/- 3.06 vs. 11.22 +/- 2.64 hr). Antipyrine clearance was decreased by only 10% (0.77 +/- 0.13 vs. 0.70 +/- 0.14 ml/min/kg). These results support the hypothesis that ciprofloxacin inhibits the oxidative metabolism in the liver. However, according to the analysis of variance data, the inhibitory effect is dose dependent. At a dose of 1000 mg daily, ciprofloxacin may induce drug interactions whereas, at a dose of 250 mg daily, the likelihood of drug interactions is improbable. In study B, cimetidine (1000 mg orally daily) and ciprofloxacin (500 mg twice daily) were administered simultaneously to eight patients. Blood samples for the determination of ciprofloxacin concentrations were taken at 0, 1, 2, 4, 6, and 12 hr after dosing on the first and seventh day of drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)

[Colorimetric determination of isoniazid in aqueous solutions and biological fluids]

Method has been developed for determination of tuberculostatic isoniazid in aqueous solutions and biological fluids. The principle of the method is that hydrazine group of isoniazid reacts with 1-fluoro-2,4-dinitrobenzene forming a red chromophor in alkaline medium. The absorbency maximum of the chromophor is at 530 nm. Biological fluids were deproteinized and diluted with acetonitrile then adjusted to pH = 8.2 with trometamol-hydrochloric acid buffer and reacted with 1-fluoro-2,4-dinitrobenzene dissolved in acetonitrile. The chromphore was measured colorimetricaly against a blank solution which did not contain isoniazid. The method was calibrated in the range of 1-30 mg/l isoniazid and reproducibility was checked with recovery % determinations.

The effect of ciprofloxacin on antipyrine metabolism

The effect of multiple-dose ciprofloxacin on antipyrine metabolism was studied in patients suffering from bacterial infections. The patients were given antipyrine 15 mg/kg intravenously before and after ciprofloxacin treatment. The dosage of ciprofloxacin was 500 mg bd by mouth for 8-10 days. Blood samples were taken at 0, 2, 4, 6, 10 h. Antipyrine total clearance was significantly decreased after ciprofloxacin treatment (0.85 +/- 0.45 vs. 0.52 +/- 0.24 ml/min/kg): elimination rate constants for antipyrine were decreased in all patients after ciprofloxacin, whereas no change in volume of distribution was observed. The average half-life of antipyrine was increased from 9.45 +/- 3.74 h to 14.92 +/- 3.32 h. In two males with advanced chronic hepatic failure the antipyrine half-lives were extremely prolonged. Our results support the hypothesis that ciprofloxacin inhibits intrinsic hepatic drug-metabolizing capacity and may be a source of clinically important drug interactions, particularly in patients with liver disease.

Pharmacokinetics of cefotaxime and desacetylcefotaxime in elderly patients

This study was undertaken to determine the effect of age on the pharmacokinetics of cefotaxime and desacetylcefotaxime after intravenous administration of 1 g cefotaxime. 30 elderly patients suffering from acute infection were enrolled in the study. They were divided into 3 subgroups (group I aged 60 to 70 years, group II aged 71 to 80 years, group III aged over 80 years) with 5 men and 5 women in each. The elimination of cefotaxime in patients aged between 60 and 80 years was slightly slower than that in young people: elimination half-lives (in men and women, respectively) in group I were 1.2 and 1.58 hours, in group II, 1.45 and 1.57 hours and in group III, 2.56 and 2.59 hours. The change in elimination of desacetylcefotaxime was similar to that of cefotaxime, but less marked. The slower elimination of cefotaxime in patients over 80 years of age may allow reduction in the dose without jeopardizing the efficacy of therapy, whereas in patients under 80 years of age the normal dosage is required.

A hypothesis for the mechanism of tumor killing by NG-hydroxymethyl-L-arginines

Arginine reacts with formaldehyde in a spontaneous equilibrium reaction yielding hydroxymethyl derivatives. They seem to have an direct and indirect inhibiting effect on cell proliferation.

Distribution of histocompatibility and leucocyte differentiation antigens in normal human colon and in benign and malignant colonic neoplasms

Monoclonal antibodies (McAbs) directed against the framework determinants of Class I and Class II products of the major histocompatibility complex (MHC) and against leucocyte differentiation antigens were used in an indirect immunoperoxidase technique to study their expression in normal, benign (adenomatous polyps) and malignant disease of the colon. Class I products (detected by the McAb 2A1) were strongly expressed on all cell types in normal and benign tissues but some carcinomas exhibited a heterogenous pattern of epithelial cell staining and 4/15 were completely negative. Class II products (detected by TDR31.1) were strongly expressed on cells (mainly B lymphocytes) within the lamina propria. In carcinomas TDR31.1 staining was mainly interstitial, but in 2/15, DR + epithelial cells were also detected. In normal and benign tissues, leucocytes (reactive with 2D1) found predominantly in the lamina propria, comprised T cells mainly of the helper/inducer (OKT4) subset, DR + cells in approx. equivalent proportion and a few OKM1+ cells mostly of macrophage morphology. Occasional intraepithelial lymphocytes were of cytotoxic/suppressor (OKT8) phenotype. In malignant neoplasms, there was wide inter and intra-tumour variation in the proportion of leucocytes which were heterogeneous with respect to cell type and confined mainly to the stroma. T cells were consistently predominant, but B cells and macrophages were also present. Two neoplasms showed unequivocal evidence of a shift (relative to peripheral blood) in favour of the OKT8+ subset, but in the majority of tumours OKT4+; and OKT8+ cells were present in roughly similar proportions. Natural killer cells (monitored with Leu7, HNK1) were virtually undetectable in both normal and malignant tissues. There were no apparent correlations between the extent and type of leucocyte infiltration, tumour differentiation or expression of MHC products. Some implications for the extrapolation of in vitro data on leucocyte function to the in vivo situation are discussed.

Age-associated pharmacokinetic changes of metronidazole

Serum concentration and urinary excretion of metronidazole were determined after p.o. administration of 500 mg to 15 young (20-25 years old) and 20 elderly (over 70) subjects. Serum levels were consistently higher and the AUCs were almost doubled in the aged group. One of the effects underlying the decrease in total clearance is the diminished renal excretion; however, the role of the reduction of distribution volume seems to be more important. Red cell binding of metronidazole significantly decreased in the aged group; this may also contribute to the reduction of distribution volume. Reduction of the standard dose of metronidazole by 30-40% is recommended in elderly patients.

Possible role of the control of arginase and methionine adenosyl transferase in the transport processes of endogenous formaldehyde and in hypermethylation

The authors believe the normal formaldehyde equilibrium in the organism to be governed by a biological control mechanism, which is thought to be closely connected to L - arginine and - indirectly - to the arginase enzyme. Arginine reacts with formaldehyde in a spontaneous equilibrium reaction yielding methylol - derivatives thus mobilizing formaldehyde. The methylol - derivatives of L - arginine were found in serum and urine. The authors assume the methylol - derivatives of L - arginine to have an inhibiting effect on cell - proliferation.

Uptake of metronidazole by human erythrocytes

In studies performed with equilibrium dialysis metronidazole was found to bind closely to human erythrocytes. In blood of haematocrit value approximately 50% of the drug was bound to erythrocytes. The ratio of bound and unbound metronidazole was influenced by the concentration of the drug and the erythrocytes. Of the intracellular proteins of erythrocytes it was the carbonic anhydrase enzyme in the first place which was responsible for binding; binding to haemoglobin was negligible. Besides binding to it, metronidazole reduced the carbonic anhydrase activity by almost 50%.

[Ultrastructure of pregnancy granuloma (angiogranuloma)]

The granuloma of pregnancy (angiogranuloma) has been studied by light-and electron microscopy. It has been revealed that granuloma of pregnancy consists chiefly of capillaries and undifferentiated connective tissue. It is a hyperplastic proliferative growth developing on the hormonal basis. In the case reported under the basement membrane presence of an electron lucent layer of fibrillar structure has been observed. Authors suppose that this phenomenon later will successfully be used in morphological differential diagnostics.