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Biomedical subjects

H Bosch

Publications and source records attributed to H Bosch.

10 recordsLinked to original sources
PubMed1992

Stereochemistry of oxidized fatty acids generated during catalytic oxygenation of lauric acid and unsaturated analogs by plant microsomes.

The capacity of microsomes from aminopyrine-induced Jerusalem artichoke (Helianthus tuberosus L.) to oxidize saturated and unsaturated fatty acids has been investigated using lauric acid and a series of unsaturated lauric acid analogs (7-, 8-, 9- and 10-dodecenoic acids) as radiolabeled substrates. In the presence of NADH, lauric acid was mono-hydroxylated principally at carbon 9. Steric analysis of this product showed a low enantiomeric excess of 28%. Mono-hydroxylated and mono-epoxidated reaction products were formed from the unsaturated analogs. The epoxidation/hydroxylation ratio was related to the position of the double bond in the aliphatic chain. The oxidation of 7-dodecenoic acid (7-DDNA) and 10-DDNA produced mainly 9-hydroxy-7-DDNA and 9-hydroxy-10-DDNA plus minor amounts of 7,8-epoxy- or 10,11-epoxylauric acid, respectively. In contrast, 8- and 9-DDNAs yielded essentially 8,9-epoxy- and 9,10-epoxylauric acids and smaller amounts of 10-hydroxy-9-DDNA and 8-hydroxy-9-DDNA, respectively. The optical purity and the absolute configuration of the major metabolites were investigated. Epoxidation of Z 8-DDNA and Z 9-DDNA occurs with high enantiomeric excesses. When the double bond was in the Z configuration, (8S,9R)/(8R,9S) 8,9-epoxylauric acid (93/7) or (9R,10S)/(9S,10R) 9,10-epoxylauric acid (89/11) were produced. In contrast, when the double bond was in the E configuration, steric analysis showed an enantiomeric ratio of 52/48 for E 8,9-epoxide and of 59/41 for E 9,10-epoxide. Z 7-DDNA led to the formation of 98% of the 9(S)-hydroxy-Z 7-DDNA enantiomer, while 9-hydroxy-Z 10-DDNA derived from Z 10-DDNA was 35% (R) and 65% (S).

Fatty Acids↗
PubMed1992

omega-Hydroxylation of Z9-octadecenoic, Z9,10-epoxystearic and 9,10-dihydroxystearic acids by microsomal cytochrome P450 systems from Vicia sativa.

A microsomal fraction from etiolated Vicia sativa seedlings incubated aerobically with [1-14C]oleic acid (Z9-octadecenoic acid) or [1-14C]9,10-epoxystearic acid or [1-14C]9,10-dihydroxystearic acid catalyzed the NADPH-dependent formation of hydroxylated metabolites. The chemical structure of compounds formed from oleic, 9,10-epoxystearic or 9,10-dihydroxystearic acids was established by gas chromatography/mass spectra analysis to be 18-hydroxyoleic acid, 18-hydroxy-9,10-epoxystearic acid and 9,10,18-trihydroxystearic acid, respectively. The reactions required O2 and NADPH and were inhibited by carbon monoxide. As expected for monooxygenase reactions involving cytochrome P450, inhibition could be partially reversed by light and all three reactions were inhibited by antibodies raised against NADPH-cytochrome P450 reductase from Jerusalem artichoke. The omega-hydroxylation of the three substrates was enhanced in microsomes from clofibrate induced seedlings.

Carbon Radioisotopes↗
PubMed1989

Arterial wall characteristics determined by intravascular ultrasound imaging: an in vitro study.

The feasibility of assessing arterial wall configuration with an intravascular 40 MHz ultrasound imaging device was investigated in an in vitro study of 11 autopsy specimens of human arteries. The system consists of a single element transducer, rotated with a motor mounted on an 8F catheter tip. Cross sections obtained with ultrasound were matched with the corresponding histologic sections. The arterial specimens were histologically classified as of the muscular or elastic type. Muscular arteries interrogated with ultrasound presented with a hypoechoic media, coinciding with the smooth muscle cells. In contrast, the media of an elastic artery densely packed with elastin fibers was as echogenic as the intima and the adventitia. On the basis of the cross-sectional image, it was possible to determine the nature of the atherosclerotic plaque. The location and thickness of the lesion measured from the histologic sections correlated well with the data derived from the corresponding ultrasound images. This study indicates that characterization of the type of artery and detection of arterial wall disease are possible with use of an intravascular ultrasound imaging technique.

Adult↗
PubMed1986

Studies on tableting properties of lactose. Part III. The consolidation behaviour of sieve fractions of crystalline alpha-lactose monohydrate.

The consolidation and compaction behaviour of sieve fractions of crystalline alpha-lactose monohydrate were studied. From mercury porosimetry measurements tablet pore surface areas were derived. At a certain compaction load it appeared that tablets compressed from small particles were generally stronger and showed a larger surface area than compacts prepared from coarse sieve fractions. By plotting compact strength against pore surface area, a unique linear relationship was obtained. From these results it can be concluded that the actual tablet surface area, being a function of both the initial particle size and applied compaction pressure, is responsible for the compact strength.

Chemistry, Pharmaceutical↗
PubMed1985

Studies on tableting properties of lactose. Part 2. Consolidation and compaction of different types of crystalline lactose.

Lactose is available in several crystalline forms, which differ in binding properties. A new method of estimating the fragmentation propensity was applied to investigate the consolidation and compaction behaviour of this excipient for direct compression. Mercury porosimetry was used to demonstrate that crystalline lactose fragments during compaction. Tablet strength was found to be dependent on the degree of fragmentation only. This finding indicates that the nature of the actual binding must be the same for the different types of crystalline lactose.

Crystallization↗