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Biomedical subjects

H Schulz

Publications and source records attributed to H Schulz.

At least 379 records · Page 21Linked to original sources
PubMed1981

4-Pentenoic acid.

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Acetyl-CoA C-Acyltransferase↗
PubMed1981

The insect neuropeptide proctolin can affect the CNS and the smooth=muscle of mammals.

The insect neurotransmitter proctolin can affect different behavioural parameters in rats after intracerebroventricular administration. Proctolin decreased the horizontal exploratory activity and induced a long-lasting analgesia in a hot-plate test. Proctolin lenghthened the passive avoidance latency of rats after post-trial treatment and also in the pre-retention test situation. The self-stimulation rate of rats was significantly diminished after i.c.v. proctolin administration. Proctolin also induced in rat and mouse ileum in vitro a dose-dependent contraction of the gut smooth-muscle that can be blocked by atropine. The results show that an invertebrate neuropeptide (or its fragments) can also be active in mammals. The physiological relevance of the effects observed recently is unknown.

Animals↗
PubMed1981

[Metabolic interactions of promethazine (author's transl)].

Owing to enzyme induction, the pretreatment of female Wistar rats with promethazine (Prothazin, Atosil) produces a shortening of the hexobarbital sleeping time, a slight increase in the relative liver weight, an increase in the N-demethylation of aminophenazone, the O-demethylation of codeine phosphate, the O-demethylation of p-nitroanisol, the glucuronidation of p-nitrophenol and the NADPH-cytochrome c reductase activity in the 9.000 g supernatant of liver homogenates. Particularly striking are the strong stimulation of the N-demethylation and the also potentiated [in contrast to the findings obtained with dioxopromethazine (Prothanon)] UDP-glucuronyltransferase activity, whereas the cytochrome P-450 concentration shows a slight trend toward increase, but this is not statistically significant. The findings obtained justify the expectation of drug interactions in case of repeated application of promethazine in the framework of a combined therapy.

Animals↗
PubMed1981

Temporal coordination of rest-activity cycle, body temperature, urinary free cortisol, and mood in a patient with 48-hour unipolar-depressive cycles in clinical and time-cue-free environments.

During medication-free observation a 66-year-old male patient showed an almost strict alternation of days with depressed mood and days with normal mood. The experiment consisted of two parts; the first was 4 weeks' observation in the psychiatric ward, while the second was 2 weeks' observation in an experimental unit where the patient was deprived of all known information on local time. In the psychiatric ward the observed circadian rhythms, i.e., the rest-activity cycle, the body temperature, the urinary free cortisol, and the mood rhythm, were all synchronized with the geophysical day. Under isolation from time cues the average rest-activity cycle duration was reduced to about 19.5 hr, whereas the body temperature and the urinary free cortisol continued to show rhythms with near-24-hr periods. The main finding of the study is the persistence of a near-48-hr periodicity in the mood fluctuation under isolation from time cues. Besides this, in the time course of body temperature and urinary free cortisol evoked components correlating with the mood cycles were found.

Activity Cycles↗
PubMed1980

Inhibition of mitochondrial fatty acid elongation by antibodies to 3-ketoacyl-CoA thiolase.

Antibodies to pig heart 3-ketoacyl-CoA thiolase inhibited almost completely and in a parallel fashion thiolase and the acetyl-CoA-dependent fatty acid elongation system present in an acetone powder extract of pig heart mitochondria. This finding leads to the conclusion that mitochondrial fatty acid elongation occurs by reversal of fatty acid oxidation. Several lines of evidence point to the thiolase-catalyzed condensation reaction as the rate-limiting step in the formation of elongated products. However, the accumulation of hydroxy acids suggests the enoyl-CoA reductase activity is limiting in the synthesis of saturated fatty acids.

Acetyl-CoA C-Acyltransferase↗
PubMed1980

The REM-NREM sleep cycle: renewal process or periodically driven process?

The question of the serial dependence of successive REM-NREM sleep cycles was examined. The experiments were performed in two different settings: 309 sleep episodes of 11 healthy young sleepers (age range, 20-36 years) were recorded under entrained conditions in the sleep laboratory; 5 of these subjects also slept in an isolation unit (underground apartment) with free-running sleep-wake cycles for a total of 107 sleep episodes. The covariances between the first three REM-NREM cycles were computed using an intraindividual cross-night approach. Significant negative covariances were observed. This result confirmed the assumption of serial dependencies between successive REM-NREM cycles. These data agree with the features of a periodically driven process and are incompatible with the alternatively hypothesized renewal model. The periodically driven process is similar in concept to the basic rest-activity cycle.

Adult↗
PubMed1980

Regulation of thiolases from pig heart. Control of fatty acid oxidation in heart.

The effects of various mitochondrial coenzymes and metabolities on the activities of 3-oxoacyl-CoA thiolase (EC 2.3.1.16) and acetoacetyl-CoA thiolase (EC 2.3.1.9) from pig heart were investigated with the aim of elucidating the possible regulation of these two enzymes. Of the compounds tested, acetyl-CoA was the most effective inhibitor of both thiolases. However, 3-oxoacyl-CoA thiolase was more severly inhibited by acetyl-CoA than was acetoacetyl-CoA thiolase. 3-Oxoacyl-CoA thiolase was also significantly inhibited by decanoyl-CoA while acetoacetyl-CoA thiolase was inhibited by 3-hydroxybutyryl-CoA as strongly as it was by acetyl-CoA. All other compounds either did not affect the thiolase activities or only at unphysiologically high concentrations. The inhibition of acetoacetyl-CoA thiolase by acetyl-CoA was linear and apparently noncompetitive with respect to CoASH (Ki = 125 microM) whereas that of 3-oxoacyl-CoA thiolase was nonlinear. However at low concentrations of acetyl-CoA the inhibition of 3-oxoacyl-CoA thiolase was linear competitive with respect to CoASH (Ki = 3.9 microM). It is concluded that 3-oxoacyl-CoA thiolase, but not acetoacetyl-CoA thiolase, will be completely inhibited by acetyl-CoA at concentrations of CoASH and acetyl-CoA which are assumed to exist intramitochondrially at state-4 respiration. It is suggested that fatty acid oxidation in heart muscle at sufficiently high concentrations of plasma free fatty acids is controlled via the regulation of 3-oxoacyl-CoA thiolase by the acetyl-CoA/CoASH ratio which is determined by the rate of the citric acid cycle and consequently by the energy demand of the tissue.

Acetyl Coenzyme A↗
PubMed1979

Action of posterior pituitary neuropeptides on the nigrostriatal dopaminergic system.

The effect of vasopressin, oxytocin and the C-terminal tripeptide of oxytocin, prolyl-leucyl-glycinamide (PLG), were tested on rotational behavior, following unilateral 6-OHDA-enduced lesion of the dopaminergic cell bodies in the substantia nigra. Intraventricular injection of lysine8-vasopressin, oxytocin or PLG caused ipsilateral (towards the lesioned side) rotation, as did peripheral administration of amphetamine. Direct local microinjection of the peptides into the substantia nigra on the intact side was without effect. The data suggest that posterior pituitary neuropeptides (vasopressin and oxytocin) caused presynaptic activation of the nigrostriatal dopaminergic terminals.

Amphetamine↗