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Biomedical subjects

H Schulz

Publications and source records attributed to H Schulz.

At least 289 records · Page 16Linked to original sources
PubMed1989

Beta-oxidation of polyunsaturated fatty acids with conjugated double bonds. Mitochondrial metabolism of octa-2,4,6-trienoic acid.

The mitochondrial beta-oxidation of octa-2,4,6-trienoic acid was studied with the aim of elucidating the degradation of unsaturated fatty acids with conjugated double bonds. Octa-2,4,6-trienoic acid was found to be a respiratory substrate of coupled rat liver mitochondria, but not of rat heart mitochondria. Octa-2,4,6-trienoyl-CoA, the product of the inner-mitochondrial activation of the acid, was chemically synthesized and its degradation by purified enzymes of beta-oxidation was studied spectrophotometrically and by use of h.p.l.c. This compound is a substrate of NADPH-dependent 2,4-dienoyl-CoA reductase or 4-enoyl-CoA reductase (EC 1.3.1.34), which facilitates its further beta-oxidation. The product obtained after the NADPH-dependent reduction of octa-2,4,6-trienoyl-CoA and one round of beta-oxidation was hex-4-enoyl-CoA, which can be completely degraded via beta-oxidation. It is concluded that polyunsaturated fatty acids with two conjugated double bonds extending from even-numbered carbon atoms can be completely degraded via beta-oxidation because their presumed 2,4,6-trienoyl-CoA intermediates are substrates of 2,4-dienoyl-CoA reductase.

Acyl Coenzyme A↗
PubMed1989

[Eczema diseases and erythemato-squamous dermatoses of aging skin--studies of the effectiveness and tolerance of Prednicarbate in various vehicles].

In an open multi-center study on 1,286 patients aged 60 years and more, we tested the efficacy and compatibility of prednicarbate (Dermatop) in various vehicles. The eczemas and erythematosquamous dermatoses of 857 patients (66.6%) disappeared within three weeks treatment. In 142 patients (11%), it took more than 3 weeks (62 day at the most) to achieve a complete healing. A very good or good tolerance was observed in 97.1% of the patients. Only in 1.5% the study had to be broken off because of a change for the worse. Prednicarbate, therefore, is especially suitable in the treatment of eczemas and chronic erythematosquamous dermatoses of aged skin.

Aged↗
PubMed1989

Evidence for the essential function of 2,4-dienoyl-coenzyme A reductase in the beta-oxidation of unsaturated fatty acids in vivo. Isolation and characterization of an Escherichia coli mutant with a defective 2,4-dienoyl-coenzyme A reductase.

For the purpose of assessing in vivo the importance of 2,4-dienoyl-CoA reductase (EC 1.3.1.34) in the beta-oxidation of unsaturated fatty acids, reductase mutants of Escherichia coli were isolated by selecting cells that were able to grow on oleate but not on petroselinic acid (6-cis-octadecenoic acid). One mutant (fadH) exhibited 12% of the 2,4-dienoyl-CoA reductase activity present in the parental strain with other beta-oxidation enzymes being essentially unaffected. Antireductase antibodies were used to show that the mutant contains a fadH gene product at a level similar to that observed in the parental strain. Thus, the mutation seems to have resulted in the synthesis of a fadH gene product with lower specific activity. The mutation was mapped in the 71-75-min region of the E. coli chromosome where no other gene for beta-oxidation enzymes has so far been located. Complementation of the mutation by F'141, which carries the 67-75.5-min region of the E. coli genome, resulted in an increase in the 2,4-dienoyl-CoA reductase activity to 80% of the level found in the parental strain. Measurements of respiration with petroselinic acid as the substrate showed rates to be linearly dependent on the 2,4-dienoyl-CoA reductase activity up to levels found in wild-type E. coli. 2,4-Dienoyl-CoA reductase, like other enzymes of beta-oxidation, was induced when E. coli was grown on a long chain fatty acid as the sole carbon source. It is concluded that 2,4-dienoyl-CoA reductase is required in vivo for the beta-oxidation of unsaturated fatty acids with double bonds extending from even-numbered carbon atoms.

Escherichia coli↗
PubMed1989

[Dermatomycoses relevant to general practice and their treatment].

Dermatomycoses probably form the biggest group in dermatological diseases. To an increasing extent even children and juveniles are affected. Choosing the right antimycotic, e.g. Cielopiroxolamine, with a broad spectrum and a high antimycotic activity in each localisation as well as good tolerability, will strongly influence therapeutic results. Whenever the dermatophytoses are deeply situated in the skin or cover large areas Griseofulvin should be used. The combination of the latter with a local antimycotic might shorten therapeutic therapy and might lead to a lower frequency of relapse.

Administration, Topical↗
PubMed1989

The 3-hydroxyacyl-CoA epimerase activity of rat liver peroxisomes is due to the combined actions of two enoyl-CoA hydratases: a revision of the epimerase-dependent pathway of unsaturated fatty acid oxidation.

Chromatography of a rat liver extract on DEAE-cellulose resulted in the near total loss of 3-hydroxyacyl-CoA epimerase activity. The activity was regained either when fractions were recombined or when purified crotonase was added to the early column fractions. A new enoyl-CoA hydratase present in these early fractions catalyzes the conversion of D-3-hydroxyacyl-CoA to 2-trans-enoyl-CoA which can be hydrated by crotonase or the peroxisomal bifunctional enzyme to L-3-hydroxyacyl-CoA. Thus, the 3-hydroxyacyl-CoA epimerase activity is due to the combined actions of two enoyl-CoA hydratases with opposite stereospecificities.

Animals↗
PubMed1989

Assay of L-3-hydroxyacyl-coenzyme A dehydrogenase with substrates of different chain lengths.

A method for assaying L-3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) which permits rate measurements with L-3-hydroxyacyl-CoA substrates of various chain lengths at physiological pH is described. The method is based on a coupled assay system in which 3-ketoacyl-CoA compounds formed by the dehydrogenase are cleaved by 3-ketoacyl-CoA thiolase (EC 2.3.1.16) in the presence of CoASH. The advantages of this assay method are its irreversibility and elimination of product inhibition. The assay procedure was used to determine the kinetic parameters (Km, Vmax) of pig heart L-3-hydroxyacyl-CoA dehydrogenase with several substrates of various chain lengths. The data obtained show the enzyme to be most active with medium-chain substrates whereas Km values for medium-chain and long-chain substrates are almost equal but much lower than those previously reported.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

Cyclooxygenase inhibition and effects of hypoxia on pulmonary circulation and gas exchange in anesthetized dogs.

To investigate whether endogenously produced prostanoids are involved in hypoxic pulmonary vasoconstriction, pulmonary hemodynamic and gas exchange parameters and eicosanoid metabolites were measured in 5 anesthetized, artificially ventilated dogs (mean body weight 27 kg). Hypoxia elicited pulmonary vasoconstriction, but blood plasma levels of thromboxane B2 (TXB2) and 6-keto-prostaglandin F 1 alpha (6kPGF1 alpha) (stable metabolites of TXA2 and prostaglandin I2, respectively) remained unchanged. Administration of the cyclooxygenase inhibitor indomethacin blocked the synthesis of prostanoids, so that 6kPGF1 alpha and TXB2 levels decreased to values below the detection level (10 pg.ml-1) both during normoxia or hypoxia, but did not affect pulmonary vascular resistance or the alveolar-arterial PO2 difference (PAi-Pa)O2. The pulmonary vascular bed remained, however, responsive to TXA2 as evidenced by infusion of the TXA2 mimetic, U 46619, which significantly increased the pulmonary vascular resistance and (PAi-Pa)O2. Our data suggest that prostanoids are not involved in eliciting the effects of hypoxia on pulmonary hemodynamics and gas exchange efficiency.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Cardiogenic mixing: mechanisms and experimental evidence in dogs.

Cardiogenic mixing was studied in seven anaesthetized closed-chest dogs undergoing mechanical ventilation by comparing single-breath washout of two poorly soluble inert gases of widely differing diffusivities (helium (He) and sulphur hexafluoride (SF6)) in normal conditions with the heart beating (control), and during reversible temporary myocardial arrest (heart arrest). Cardiac arrest of approximately 20 s duration was induced repeatedly (8-15 times) by intracoronary injection of acetylcholine (approximately 35 mg) facilitated by a non-occluding 7-French gauge angiographic catheter maintained in the left coronary artery. After equilibration of lung gas with 1% helium and 1% SF6, single breath, constant flow expirograms were recorded in the tracheal tube by mass spectrometry after inspiration of test gas-free air. Series deadspace (VD) and relative alveolar slope (S) (increment of expired partial pressure, normalized to mixed expired-inspired partial pressure difference per increment of expired volume (S = (delta P/(PE-P1]/delta VE litre-1], were determined as indices for intrapulmonary gas mixing. The effects attributable to the action of the heart were quantified by the heart arrest: control ratio of VD and S, which were not significantly different from unity (P greater than 0.05) (VD: 0.95 (SD 0.05) for helium and 0.94 (0.07) for SF6; S:1.03 (0.10) for helium and 1.05 (0.14) for SF6. The He:SF6 ratios of VD and S (0.90 and 0.64, respectively), indicating diffusion dependent separation of gases, also were unaffected by the mechanical action of the heart. The data indicate that convective mixing by the mechanical action of the heart did not significantly enhance intrapulmonary mixing and transport.

Acetylcholine↗
PubMed1989

Elastase and papain inhibition by serum of mammals.

The protease-antiprotease imbalance concept has gained wide acceptance in reference to experimental animal models of human pulmonary emphysema. The destructive process may be induced by proteolytic enzymes such as porcine pancreas elastase (E) or papain (P), or by oxidants such as chloramine T (CT) which cause inactivation of alpha-1-antiprotease. The susceptibility to development of severe emphysema has been found to differ among animal species. We investigated the inhibition of elastase and papain by serum of seven species (rat, dog, human, rabbit, sheep, hamster, mini pig) and the effect of CT on serum inhibition. The relative inhibitor concentration of serum was expressed in terms of its inhibitor capacity for elastase and papain (EIC and PIC) defined as number of inhibited units (U) of enzyme catalysed hydrolysis of chromogenic peptide substrate (SAPNA and BAPNA) per unit of serum. The effect of CT on enzyme inhibition was quantified in terms of fractional loss of inhibition relative to control. The serum concentration of inhibitor was highest in the rat (EIC 8642 +/- 989 microU/microliter, PIC 214.2 +/- 110.3 microU/microliter; means +/- SD). Next in order of decreasing EICs were dog, human, rabbit, sheep, hamster, and mini pig exhibiting the lowest EIC (2523 +/- 184 microU/microliter) while sheep had lowest PIC (39.6 +/- 3.5 microU/microliter). The EIC/PIC ratio varied from 20 (mini pig) to about 100. The reduction of elastase inhibition after CT exposure of serum was high (80-100%) in rat, dog, human, and hamster, moderate (40%) in mini pig and rabbit, and low (10%) in sheep. Because papain was directly affected by CT the effect of CT on papain inhibition could not be analysed. The data suggest that the intrinsic antiprotease and antioxidant screen varies among experimental animals. For the purpose of animal models of emphysema, hamster appears to be most susceptible to the progressive destruction of lung parenchyma elicited by experimental burden of proteases or oxidants.

Animals↗
PubMed1988

4-Bromo-2-octenoic acid specifically inactivates 3-ketoacyl-CoA thiolase and thereby fatty acid oxidation in rat liver mitochondria.

In an attempt to develop a compound which would specifically inhibit 3-ketoacyl-CoA thiolase (EC 2.3.1.16) in whole mitochondria, 4-bromo-2-octenoic acid was synthesized and studied. After rat liver mitochondria were preincubated with 4-bromo-2-octenoic acid for 3 min, respiration supported by either palmitoylcarnitine or pyruvate was completely abolished, whereas no inhibition was observed with rat heart mitochondria. Addition of carnitine stimulated respiration supported by pyruvate without relieving inhibition of palmitoylcarnitine-dependent respiration. Hence, this compound seems to be a specific inhibitor of beta-oxidation. When the enzymes of beta-oxidation were assayed in a soluble extract prepared from mitochondria preincubated with 4-bromo-2-octenoic acid, only 3-ketoacyl-CoA thiolase was found to be inactivated. 4-Bromo-2-octenoic acid is metabolized by mitochondrial beta-oxidation enzymes to 3-keto-4-bromooctanoyl-CoA which effectively and irreversibly inhibits 3-ketoacyl-CoA thiolase but not acetoacetyl-CoA thiolase (EC 2.3.1.9). Even though 3-keto-4-bromooctanoyl-CoA inhibits the latter enzyme reversibly, 4-bromo-2-octenoic acid does not inhibit ketogenesis in rat liver mitochondria with acetylcarnitine as a substrate. It is concluded that 4-bromo-2-octenoic acid specifically inhibits mitochondrial fatty acid oxidation by inactivating 3-ketoacyl-CoA thiolase in rat liver mitochondria.

Acetyl-CoA C-Acyltransferase↗
PubMed1988

High-performance liquid chromatographic characterization of some medical plant extracts used in cosmetic formulas.

Rapid and reliable methods are presented for the characterization of biologically active and/or characteristic constituents in aqueous extracts of Hamamelis virginiana, Matricaria chamomilla, Achillea millefolium, Thymus vulgaris, Althaea officinalis and Cinchonia spp. Prior to high-performance liquid chromatographic (HPLC) separation a clean-up step was performed using a solid-phase extraction system. The purified extracts were analysed by HPLC coupled with a diode-array detector and a fluorescence detector. In some instances, previously unreported components of the aqueous plant extracts were found.

Amino Acids↗