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Biomedical subjects

H Vanderhaeghe

Publications and source records attributed to H Vanderhaeghe.

At least 19 recordsLinked to original sources
PubMed1991

[Nontraditional beta-lactam antibiotics].

In recent years several beta-lactam derivatives have been obtained, which differ markedly from the traditional penicillins and cephalosporins, some of which have been introduced in the clinic. Clavulanic acid has an oxygen atom instead of sulfur but differs also markedly on C2 and C6. This inhibitor of penicillinase is used in association with amoxicillin and ticarcillin. Sulbactam and tazobactam are other beta-lactamase inhibitors, which are also used in association with penicillins. In the carbapenems sulfur is replaced by a carbon atom and a double bond is also present. Thienamycin, which is rather labile, has been transformed into a more stable product, imipenem, which is used in the treatment of infections with gram-positive and -negative bacteria. Other carbapenems are being studied. Several synthetic penems also present an interesting activity and may be used in medicine. Monobactams are monocyclic beta-lactams isolated from bacteria. By modification of the natural products aztreonam was obtained, a substance which is used in the treatment of infections with gram-negative bacteria. Other monobactams, prepared by total synthesis like aztreonam, are being studied.

Anti-Bacterial Agents↗
PubMed1989

Quantitative analysis of chlortetracycline and related substances by high-performance liquid chromatography.

Isocratic high-performance liquid chromatography on Zorbax C8 7 microns allows quantitative determination of chlortetracycline, 4-epichlortetracycline, tetracycline, demethylchlortetracycline and isochlortetracycline using a mobile phase containing dimethylsulphoxide, 1 M perchloric acid and water (35:5:60). The minor impurities anhydrochlortetracycline and 4-epianhydrochlortetracycline, which are more strongly retained can be determined using a second isocratic system with a mobile phase containing more organic modifier. The method has been used for the comparison of official standards and for the analysis of a number of commercial samples.

Chlortetracycline↗
PubMed1989

A collaborative study of the analysis of doxycycline hyclate by high-performance liquid chromatography on polystyrene-divinylbenzene packing materials.

An improved method for the analysis of doxycycline hyclate by high-performance liquid chromatography using polystyrene-divinylbenzene column packings is described. The separation obtained with this method was compared with that of other, recently described methods. The improved method was examined in a collaborative study involving five separate laboratories, using 11 different columns and four discrete samples. The main component and impurities were determined. An analysis of variance showed absence of consistent laboratory bias and presence of significant laboratory-sample interaction. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations (RSD) of the result of the determination of doxycycline, were found to be 0.9 and 1.2%, respectively.

Chromatography, High Pressure Liquid↗
PubMed1988

Thin-layer chromatographic study of the metabolites of erythromycins in the Wistar rat.

The metabolites of erythromycin A, anhydroerythromycin A, N-demethylerythromycin A and erythromycin B in the Wistar rat were studied by thin-layer chromatography. In some experiments germ-free rats, rats with a cannulated bile duct and a gastrectomized rat were used. The erythromycins examined were shown to undergo two principal changes, N-demethylation and acid-catalysed degradation. It was demonstrated that the stomach and the liver are not the sole sites of acid degradation and demethylation of erythromycins, respectively. Erythromycin A gives three principal metabolites, anhydroerythromycin A, anhydro-N-demethylerythromycin A and N-demethylerythromycin A, and erythromycin A enol ether and N-demethylerythromycin A enol ether are present to a minor extent. 5-O-Desosaminylerythronolide A was also identified, suggesting the presence of an erythromycin glycosidase.

Animals↗
PubMed1987

Optimization of the separation of erythromycin and related substances by high-performance liquid chromatography.

An improved high-performance liquid chromatographic method for analysis of erythromycin is described. The separation can be performed under mild conditions of pH (6.5) and temperature (35 degrees C) on C8 and C18 silica-based reversed-phase materials of different origins. The mobile phase, with a flow-rate of 1.5 ml/min, contained various amounts of acetonitrile (25-40%, v/v), 5% (v/v) 0.2 M ammonium phosphate buffer pH 6.5, 20% (v/v) 0.2 M tetramethylammonium phosphate and water. UV detection at 215 nm allows quantitation of erythromycins A, B and C, N-demethylerythromycin A, erythromycin A enol ether and anhydroerythromycin A. The column history plays a major role, older columns often giving better separations.

Chromatography, High Pressure Liquid↗
PubMed1987

Quantitative analysis of oxytetracycline and related substances by high-performance liquid chromatography.

Isocratic high-performance liquid chromatography on PLRP-S 8-microns poly(styrene-divinylbenzene) copolymer allows complete separation of oxytetracycline, 4-epioxytetracycline, tetracycline, anhydrooxytetracycline, alpha- and beta-apooxytetracycline. The mobile phase was tert.-butanol-0.2 M phosphate buffer pH 8.0-0.02 M tetrabutylammonium sulphate pH 8-0.0001 M sodium ethylenediaminetetraacetate pH 8.0-water (5.9:10:5:10:78.1, m/v/v/v/v). With this isocratic method, 2-acetyl-2-decarboxamidooxytetracycline is only partly resolved from oxytetracycline. The separation and the detection limits can be improved by the use of gradient elution. Gradient elution was used for the comparison of official standards and for the analysis of a number of commercial samples, and to monitor the stability of oxytetracycline hydrochloride during storage in the solid state for about 6 years at various temperatures.

Chemical Phenomena↗
PubMed1987

Sensitive and rapid assay on MT-4 cells for detection of antiviral compounds against the AIDS virus.

Human immunodeficiency virus (HIV) infection of MT-4 cells, an HTLV-I-transformed T-cell line, proved to be a rapid and sensitive assay system for the detection of potential antiviral drugs effective against the acquired immune deficiency syndrome (AIDS). Four days after HIV inoculation of the MT-4 cells, viral antigen expression was monitored in parallel with indirect immunofluorescence microscopy and laser flow cytofluorography. When 3'-azido-2',3'-dideoxythymidine (AzddThd, AZT) and 2',3'-dideoxycytidine (ddCyd) were evaluated under these conditions, they inhibited viral antigen expression at a minimum (33% inhibitory) concentration of 0.0004 and 0.02 microM, respectively. Similar minimum effective concentrations were found for AzddThd and ddCyd in assays where inhibition of viral cytopathogenicity was based on cell survival. While laser flow cytofluorography could be best adapted for quantitative measurements, cell survival and reconstitution of disrupted cell aggregates gave an equally rapid and sensitive endpoint; and the latter may be ideally suited for preliminary drug screening.

Antigens, Viral↗
PubMed1987

3'-substituted 2',3'-dideoxynucleoside analogues as potential anti-HIV (HTLV-III/LAV) agents.

A series of 2',3'-unsaturated and 3'-substituted 2',3'-dideoxynucleoside analogues of purines and pyrimidines have been synthesized and evaluated for their inhibitory activity against human immunodeficiency virus (HIV). The 2',3'-unsaturated analogues of 2',3'-dideoxycytidine (ddeCyd) and 2',3'-dideoxythymidine (ddeThd), 3'-azido-2',3'-dideoxythymidine (AzddThd), 3'-fluoro-2',3'-dideoxythymidine, 2',3'-dideoxycytidine (ddCyd), and 2',3'-dideoxyadenosine (ddAdo) emerged as the most potent inhibitors of HIV-induced cytopathogenicity in the human T lymphocyte cell lines ATH8 and MT4. In ATH8 cells ddCyd, ddeCyd, and ddAdo had the highest therapeutic index whereas in MT4 cells AzddThd, ddThd, ddCyd, and ddAdo were the most selective. Derivatives from ddThd in which the substituent group was linked to the 3'-carbon atom via a thio, sulfonyl, or oxygen bridge were far less inhibitory to HIV than was AzddThd.

Antiviral Agents↗
PubMed1987

Identification of novel erythromycin derivatives in mother liquor concentrates of Streptomyces erythraeus.

The identification of five novel compounds, pseudo-erythromycin A-6,9-hemiketal, 8,9-anhydro-pseudo-erythromycin A-6,9-hemiketal, 8,9-anhydro-pseudo-N-demethylerythromycin A-6,9-hemiketal, 5-O-beta-D-desosaminylerythronolide A and 15-nor-erythromycin C, in mother liquor concentrates of Streptomyces erythraeus is described. The pseudo-erythromycin derivatives are characterized by a 12-membered macrocyclic ring as a result of C13----C11 trans-lactonization. The five compounds have very little antimicrobial activity.

Bacteria↗
PubMed1986

Synthesis of delta 3-1-methylene-1-carbacephems.

The total synthesis of (+/-)-1-methylene-2,2- dimethyl-7-amino-1-carbacephem-4-carboxylic acid (1) is described. The reaction scheme was essentially that described by Christensen et al. for the synthesis of (+/-)-1-carbacephems. In vitro antibacterial activities of the 7-phenoxyacetyl and 7-D-alpha-phenylglycyl derivatives of 1 were compared with those of 7-(phenoxyacetamido)desacetoxycephalosporanic acid and cefalexin. Derivatives of 1 were 2-4 times less active against most of the sensitive organisms than the corresponding 7-aminodesacetoxycephalosporanic acid analogues. The activity of the 7-D-alpha-phenylglycyl derivative of 1 however was about 20 times lower than that of cefalexin when measured against Staphylococcus aureus ATCC 6538P.

Cephalexin↗
PubMed1985

Separation of erythromycin and related substances by high-performance liquid chromatography on poly(styrene-divinylbenzene) packing materials.

A comparative evaluation of three brands of poly(styrene-divinylbenzene) copolymers, Hamilton PRP-1 (10 micron), Rogel (8 micron) and TSK-Gel (10 micron), as column packing materials for high-performance liquid chromatographic separation of erythromycins is presented. Erythromycins A, B and C, anhydroerythromycin A, erythromycin A enol ether, N-demethylerythromycin A, anhydro N-demethylerythromycin A and N-demethylerythromycin A enol ether were chromatographed. The effects of column temperature, concentration of organic modifier in the mobile phase, concentration of phosphate buffer, the addition of quaternary ammonium salts and pH are described. The best separations were obtained on TSK-Gel with the mobile phase acetonitrile-methanol-0.2 M tetramethylammonium hydroxide pH 8.0-0.2 M phosphate buffer pH 8.0-water (30:15:25:5:25). PRP-1 and Rogel gave equally good separations but with higher retention volumes.

Animals↗
PubMed1985

Determination of the stability of tetracycline suspensions by high performance liquid chromatography.

High performance liquid chromatography was used to examine the stability of tetracycline suspensions, prepared according to the Formulary of the Dutch Pharmacists and the National Formulary v (Belgium). The influence of the nature of the buffer salt, of the pH, and of the temperature and time of storage are discussed. At slightly acid pH (4 to 5.5) and at room temperature suspensions are stable for at least three months.

Chromatography, High Pressure Liquid↗
PubMed1985

Quantitative determination of amoxicillin and its decomposition products by high-performance liquid chromatography.

Amoxicillin, amoxicilloates, amoxicillin oligomers and amoxicillin piperazine-2,5-dione are separated by reversed-phase (C8) high-performance liquid chromatography with gradient elution. Quantitative results are reported for a number of samples. Amoxicillin trihydrate samples mostly contain amoxicilloate as the main impurity. Samples of the sodium salt also contain the piperazine-2,5-dione and the dimer. Higher oligomers such as the trimer and tetramer were not present in significant amounts. Several samples were also analysed by a mercurimetric titration method.

Amoxicillin↗
PubMed1985

Synthesis and antiviral activity of the carbocyclic analogues of (E)-5-(2-halovinyl)-2'-deoxyuridines and (E)-5-(2-halovinyl)-2'-deoxycytidines.

The carbocyclic analogues of the potent and selective antiherpes agents (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU), (E)-5-(2-iodovinyl)-2'-deoxyuridine (IVDU), and (E)-5-(2-bromovinyl)-2'-deoxycytidine (BVDC) were synthesized by conventional methods with use of carbocyclic 2'-deoxyuridine as starting material. C-BVDU, C-IVDU, and C-BVDC were equally selective, albeit slightly less potent, in their antiherpes action than BVDU, IVDU, and BVDC. Although resistant to degradation by pyrimidine nucleoside phosphorylases, C-BVDU did not prove more effective than BVDU in the systemic (oral, intraperitoneal) or topical treatment of HSV-1 infections in mice.

Animals↗