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Biomedical subjects

W Heller

Publications and source records attributed to W Heller.

At least 109 records · Page 6Linked to original sources
PubMed1986

[Effect of L-carnitine on post-stress metabolism in surgical patients].

The positive influence of L-carnitine administration on postaggression metabolism was investigated. Clinical examinations were executed on three groups of patients K1, K2, K3). Comparable surgical operations like stomach- and intestinal- resections were performed on these groups of patients. During the first three days after operation a nutritional diet (parenteral, standardized hypocaloric) with (K2: 2 g; K3: 4g) and without L-carnitine (K1) was given. The effects of L-carnitine administration were evaluated by the following parameters: free fatty acids (FFS), triglycerides (TG), beta-hydroxybutyric acid (beta-OH-BS), acetacetate (ACAC), blood sugar (BZ), insulin (INS), lactate (LAK), pyruvate (PYR), total protein (GE), cholinesterase (CHE), urea production rate (PU), nitrogen of alpha-aminogroups (alpha-AN), nitrogen balance (NB), catabolic index (KI), BUN-Creatinine-quotient (B/K), total carnitine (GC), free carnitine (FC), acetyl carnitine (AC) and also the ratio between acetyl carnitine and free carnitine (AC/FC) in serum and urine. The results show no statistical significance. But they could lead to the following conclusions: Carnitine obviously reduces the insulin resistance. But it does not influence the post-operative perturbation of glucose-utilization. Carnitine reinforces the utilization of long chain fatty acids and thus improves the energy conversion. Carnitine leads to an earlier positive nitrogen balance. By giving 4 g of carnitine a day, already after three days a repletion of tissue deposits is possible, and a dose dependence for carnitine administration exists for the utilization of long chain fatty acids and the repletion of tissue deposits.

Adult↗
PubMed1985

Elicitor induction of a microsomal 5-O-(4-coumaroyl)shikimate 3'-hydroxylase in parsley cell suspension cultures.

Microsomal preparations from parsley cell suspension cultures challenged with an elicitor from Phytophthora megasperma f.sp. glycinea (Pmg) catalyze the formation of trans-5-O-caffeoylshikimate from trans-5-O-(4-coumaroyl)shikimate. Neither the cis isomer nor free 4-coumarate, 4-coumaroyl-CoA, or 5-O-(4-coumaroyl)quinate are substrates for this enzyme. The reaction is strictly dependent on NADPH as a reducing cofactor and on molecular oxygen. NADH, ascorbic acid, and 6,7-dimethyl-5,6,7,8-tetrahydropterine cannot substitute for NADPH. However, NADH enhances enzyme activity observed in the presence of NADPH. Cytochrome c and carbon monoxide inhibit the hydroxylation reaction, suggesting a cytochrome P-450-dependent mixed-function monooxygenase.

Caffeine↗
PubMed1985

[Autotransfusion and plasmapheresis in preparation for surgery. Behavior of coagulation].

With the current day implementation of methods of autotransfusion one retransfuses if possible only washed red cell concentrates and eliminates the plasma. In the case of operations where patients undergo large blood loss, one must effect a substitution for the lost plasma volume and the lost clotting factors. In addition to electrolyte and colloidal solutions one can use a substitution of homologous and also autologous fresh frozen plasma (FFP). The effects of different substitutes on the clotting reaction has been investigated in 47 patients on whom extensive orthopaedic and also traumatologic surgical operations have been performed. By the combination of homologous blood and homologous FFP as also with autologous red cells and homologous FFP the clotting reactions remain the same. This determines the advantages of autotransfusion as compared with conventional techniques but, in addition, there is a saving in the usage of homologous blood. Where an operation can be planned in advance, the necessary FFP can be obtained from the patient. By utilisation of autologous FFP the operative and post- operative blood losses are reduced. As a result it is possible e.g. in total hip prosthesis, in approximately 90% of all cases, to operate without using homologous blood or plasma. The determined stability of AT III in autologous plasma--without AT III prophylaxis of thrombosis by Heparin is ineffective--and all other clotting factors leads to an expectancy of a not activated clotting mechanism and at the same time to low thrombosis risks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

N-malonyltransferases from peanut.

Three distinct N-malonyltransferases were purified from peanut seedlings, accepting either anthranilic acid, D-tryptophan, or 3,4-dichloroaniline, respectively, as a substrate. Partially purified malonyl-CoA:D-tryptophan malonyltransferase also catalyzed the formation of the corresponding malonic acid conjugate when 1-aminocyclopropane-1-carboxylic acid was employed as a substrate. These N-malonyltransferases were clearly distinguished from several O-malonyltransferase activities also present in the same seedlings. N-Malonic acid conjugates have been previously isolated from peanut either as a natural constituent or after feeding with xenobiotics. By analogy to the results reported with cultured parsley cells, multiple malonyltransferases in peanut may have a role in vacuolar transport. Crude extracts of young peanut seedlings were incapable of hydrolyzing the respective N-malonic acid conjugates. However, dialyzed extracts of older plants released malonic acid from malonyl-1-aminocyclopropane-1-carboxylic acid but not from malonyl-3,4-dichloroaniline, suggesting that some N-malonic acid conjugates may be metabolized in plants which are approaching senescence.

Acyltransferases↗
PubMed1984

Induction of phytoalexin synthesis in soybean. Stereospecific 3,9-dihydroxypterocarpan 6a-hydroxylase from elicitor-induced soybean cell cultures.

A microsomal preparation from elicitor-challenged soybean cell suspension cultures catalyzes an NADPH-dependent and dioxygen-dependent 6a-hydroxylation of 3,9-dihydroxypterocarpan to 3,6a,9-trihydroxypterocarpan. The latter is a precursor for the soybean phytoalexin glyceollin. No reaction is observed with NADH. The 6a-hydroxylase is inhibited by cytochrome c. Optical rotatory dispersion spectra of the enzymatic product formed from racemic dihydroxypterocarpan and of the remaining unreacted substrate proved that the product has the natural (6aS, 11aS)-configuration and that hydroxylation proceeds with retention of configuration. The 6a-hydroxylase was also found in elicitor-challenged soybean seedlings. The results indicate that the 6a-hydroxylase is specifically involved in the biosynthesis of glyceollin.

Benzopyrans↗
PubMed1983

Induction and characterization of a microsomal flavonoid 3'-hydroxylase from parsley cell cultures.

A microsomal preparation from irradiated parsley cell cultures catalyses the NADPH and dioxygen-dependent hydroxylation of (S)-naringenin [(S)-5, 7, 4'-trihydroxyflavanone] to eriodictyol (5, 7, 3', 4'-tetrahydroxyflavanone). Dihydrokaempferol, kaempferol, and apigenin were also substrates for the 3'-hydroxylase reaction. In contrast prunin (naringenin 7-O-beta-glucoside) was not converted by the enzyme. The microsomal preparation, which also contains cinnamate 4-hydroxylase, did not catalyse hydroxylation of 4-coumaric acid to caffeic acid. 3'-Hydroxylase activity is partially inhibited by carbon monoxide in the presence of oxygen as well as by cytochrome c and NADP+. These properties suggest that the enzyme is a cytochrome P-450-dependent flavonoid 3'-monooxygenase. Pronounced differences in the inhibition of flavonoid 3'-hydroxylase and cinnamate 4-hydroxylase were found with EDTA, potassium cyanide and N-ethylmaleimide. Irradiation of the cell cultures led to increase of flavonoid 3'-hydroxylase activity with a maximum at about 23 h after onset of irradiation and subsequent decrease. This is similar to light-induction of phenylalanine ammonialyase and cinnamate 4-hydroxylase. In contrast, treatment of the cell cultures with a glucan elicitor from Phytophthora megasperma f. sp. glycinea did not induce flavonoid 3'-hydroxylase nor chalcone isomerase but caused a strong increase in the activities of phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, and NADPH--cytochrome reductase. The results prove that flavonoid 3'-hydroxylase and cinnamate 4-hydroxylase are two different microsomal monooxygenases.

Catalysis↗
PubMed1983

Conformational changes of apigenin 7-O-(6-O-malonylglucoside), a vacuolar pigment from parsley, with solvent composition and proton concentration.

Malonylated apigenin 7-O-glucoside was prepared from malonyl-CoA and apigenin 7-O-glucoside using a malonyltransferase from parsley cell cultures. The enzyme product, as well as the flavonoid substrate, was analyzed by high-resolution nuclear magnetic resonance spectroscopy, confirming that malonic acid had been attached to the primary hydroxyl of the glucose moiety of apigenin 7-O-glucoside. During these studies in several solvents, it became apparent that, in particular, the chemical shift of H-6" A and the coupling constants J5",6"A and J5",6"B were dependent on solvent composition and proton concentration. Similar changes of sugar proton resonance frequencies were also observed with methyl 6-O-malonyl-beta-D-glucopyranoside, but not with apigenin 7-O-[6-O-(4-coumaroyl)glucoside]. The change of coupling constants is ascribed to a conformational modification of the sugar portion in the malonylglucosides. Malonylated flavonoid glycosides are exclusively located within the vacuoles of parsley cells. We propose that acylation of flavonoid glycosides which are synthesized in the cytoplasm facilitates transport of the substrates into the vacuole. The conformational modification which is induced by changes in proton concentration may provide a mechanism to trap flavonoids in situ.

Apigenin↗
PubMed1983

Substrate specificity of chalcone synthase from Petroselinum hortense. Formation of phloroglucinol derivatives from aliphatic substrates.

The substrate specificity of chalcone synthase, the key enzyme of flavonoid biosynthesis, was investigated. A purified enzyme preparation from cell suspension cultures of parsley (Petroselinum hortense) catalyzed chain elongations with acetate units from malonyl-CoA, using various aromatic and aliphatic CoA esters as starter molecules. Malonyl-CoA could not be replaced by malonyl acyl carrier protein in the standard chalcone synthase assay. Butyryl-CoA, hexanoyl-CoA, and benzoyl-CoA served as substrates for the condensation reaction with similar efficiency as 4-coumaroyl-CoA, the natural substrate of the enzyme. Acetyl-CoA and octanoyl-CoA were relatively poor substrates. Among the products formed with the two most efficient aliphatic substrates tested, butyryl-CoA and hexanoyl-CoA, were the respective chalcone analogues, phlorobutyrophenone and phlorocaprophenone. The possibility is discussed that chalcone synthase and the corresponding enzyme of fatty acid synthesis in higher plants, beta-ketoacyl-acyl carrier protein synthase, have a common evolutionary origin.

Acetyl Coenzyme A↗
PubMed1983

Asymmetry of perception in free viewing of chimeric faces.

We have devised a new free-vision task to index functional cerebral asymmetry for processing facial characteristics. Confirming its sensitivity to properties of lateralized hemispheric functions, left- and right-handers were clearly differentiated on this task with respect to several aspects of performance that conform with known differences between handedness groups in hemispheric asymmetry. Additionally, there were highly reliable and stable individual differences in perceptual asymmetries within handedness. Analyses of items in the task revealed that most of the differences between items in the asymmetries they elicited were random.

Brain↗
PubMed1983

Are variations among right-handed individuals in perceptual asymmetries caused by characteristic arousal differences between hemispheres?

We propose that much of the variance among right-handed subjects in perceptual asymmetries on standard behavioral measures of laterality arises from individual differences in characteristic patterns of asymmetric hemispheric arousal. Dextrals with large right-visual-field (RVF) advantages on a tachistoscopic syllable-identification task (assumed to reflect characteristically higher left-hemisphere than right-hemisphere arousal) outperformed those having weak or no visual-field asymmetries (assumed to reflect characteristically higher right-hemisphere than left-hemisphere arousal). The two groups were equal, however, in asymmetries of error patterns that are thought to indicate linguistic or nonlinguistic encoding strategies. For both groups, relations between visual fields in the ability to discriminate the accuracy of performance followed the pattern of syllable identification itself, suggesting that linguistic and metalinguistic processes are based on the same laterally specialized functions. Subjects with strong RVF advantages had a pessimistic bias for rating performance, and those with weak or no asymmetries had an optimistic bias, particularly for the left visual field (LVF). This is concordant with evidence that the arousal level of the right hemisphere is closely related to affective mood. Finally, consistent with the arousal model, leftward asymmetries on a free-vision face-processing task became larger as RVF advantages on the syllable task diminished and as optimistic biases for the LVF, relative to the RVF, increased.

Arousal↗