PubMed Health⌕ Search

Biomedical subjects

W Buck

Publications and source records attributed to W Buck.

16 recordsLinked to original sources
PubMed1995

Distribution behaviour of 131-iodine labelled trans-N,N'-bis-(ethoxy-carbonyl)-N-[4-(3-iodo-4-methoxyphenyl)butyl]-N' -5- phenylpentyl)-1,4-cyclohexanedimethanamine.

The title compound 9, which is a prodrug, and its active metabolite 7 were labelled with 131I (7*/9*) to investigate their pharmacokinetic behaviour, including the distribution between stomach, gut, muscle, blood, lung, liver, kidney, adrenal gland, heart, and spleen. Four hours after oral administration of 7* to mice only 3% of the dose had been absorbed from the g.i. tract. After 24 h 54% of the radioactivity still is found the gut, predominantly in the small intestine. These results explain why 7, which is a potent antiplatelet drug in vitro, shows no antithrombotic effect in vivo. In contrast, the produg 9/9* is absorbed considerably, i.e. up to 50% in 4 h from the g.i. tract depending on the dose applied and the vehicle used. At doses in the micromolar range the absorption appears to be diffusion limited. The highest concentrations are found in the liver and the kidneys suggesting a first pass effect of 7 followed by renal excretion. From the blood levels achieved, the dose necessary for an antithrombotic effect has been calculated to be about 100 mg/kg. In summary, the N-ethoxycarbonyl derivatives of oligoamines appear to be suitable prodrugs for oral administration of oligoamines.

Animals↗
PubMed1988

[Double-blind study of the effect of cyclotropium bromide on the smooth musculature of the esophagus. Description of a test of spasmolytic action].

Esophageal manometry can be employed to quantify the effects of antispasmodics in human subjects. Because of this, the effects of intravenously administered ciclotropium bromide (CTB) or hyoscine N-butylbromide (HNB) on esophagus smooth muscles were tested by manometry against saline (placebo) in 10 healthy volunteers in a randomized double-blind study. Tolerance as well as efficacy of CTB and HNB were evaluated. CTB administered intravenously significantly reduced the peristalsis amplitude following dry and wet acts of swallowing for at least 90 min. HNB caused a similar reduction which lasted only for 10 min. No reduction was observed following placebo except for physiological fluctuations. This shows that intravenous CTB causes a long-lasting reduction of smooth muscle contractions following the act of swallowing. Following placebo the lower esophageal sphincter (LES) pressure was higher than baseline values during the entire 90 min measurement period. CTB administration resulted in a significant reduction of the LES pressure compared to placebo. After HNB administration there was an initial decrease of the LES pressure lasting 30 min which was followed by an increase. None of the 3 drugs affected systolic or diastolic blood pressure. The heart rate did not change following placebo. After HNB administration heart rate was elevated at 15 min but decreased thereafter and was significantly lower than the baseline value at 45 min and later. CTB caused a significant increase of the heart rate at all sampling times. This increase corresponds well with the side-effects reported by 7 of the 10 subjects.

Adult↗
PubMed1987

Lack of hepatic microsomal metabolism of deoxynivalenol and its metabolite, DOM-1.

Rat hepatic microsomal preparations were used to study the metabolism of deoxynivalenol (DON) and its metabolite 3 alpha,7 alpha,15-trihydroxytrichothec-9,12-dien-8-one (DOM-1). The N-demethylation of ethylmorphine was monitored to assess the viability of the mixed-function oxidase. DON was incubated with microsomes and an NADPH-generating system. Samples were removed from the incubation system and analysed for DON using an HPLC equipped with a UV detector. After incubation for 30 min, there was no evidence of disappearance of DON or of the presence of new metabolites; neither was microsomal NADPH oxidation altered by the addition of DON. Rat and pig hepatic microsomal preparations were used to assess DON glucuronidation, using p-nitrophenol disappearance to check the viability of the microsomal glucuronidating system. When DON was incubated with microsomes and 14C-labelled uridine 5'-diphosphoglucuronic acid, no radioactivity was detected in the TLC zone where the glucuronide was expected. Three rats and one pig were dosed orally with 2 mg DON/kg and samples of their urine and faeces were extracted and incubated with beta-glucuronidase or with buffer only. No differences in DON or DOM-1 concentrations were detected between samples incubated with or without beta-glucuronidase. These results suggest that DON was neither bioactivated to a more toxic product nor oxidized to a less toxic compound by the rat hepatic mixed-function oxidase system. Likewise, DOM-1 was not reactivated or metabolized by this system. Neither DON nor DOM-1 glucuronides were formed either in in vitro liver systems or in vivo.

Animals↗
PubMed1980

[Driving behavior of cardiovascular patients as affected by beta receptor blockers].

18 male patients under betablocker therapy adapted to their individual stage of hypersympathicotonic circulatory regulation disturbances were tested in a motor-vehicle simulator to find out possible changes of their driving ability. Besides observing driving-style and reactions, the following parameters were controlled: blood pressure, time of pulse waves, heart rate. Speeds of deviation angles (= deviation from straight line per time unit) decreased significantly. No differences between tests under betablocker medication and without it could be demonstrated, neither in simple-reaction times nor in the more complex multiple-reaction times, which can be compared with realistic traffic situations. Blood pressure and heart rate showed more significant decreases after medication than in tests without previous betablocker treatment. The results prove that the betablocking agent Bupranolol does not influence the ability of car-driving, not even in case of semichronical application.

Attention↗
PubMed1976

Herd health status of animals exposed to polybrominated biphenyls (PBB).

The health status of 16 herds of dairly cattle exposed to low levels of polybrominated bipenyl (PBB) was compared with that of 15 control herds. Milk production of the contaminated herds was not significantly changed in 1972, 1973, and 1974 and was not significantly different from that of control herds in the same years. Mortality of adult cows and calves, the percentages of cows culled from the herds because of old age and low production, disease, or sterility, and the general health conditions were similar in the two groups. Serum concentrations of calcium, glucose, and cholesterol in contaminated herds were significantly different from those of the control herds, but the relationship to PBB exposure needs further investigation.

Animal Feed↗