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Biomedical subjects

H J Hapke

Publications and source records attributed to H J Hapke.

At least 19 recordsLinked to original sources
PubMed1997

Pharmacokinetic study of dipyrone metabolite 4-MAA in the horse and possible implications for doping control.

The pharmacokinetic behaviour of dipyrone metabolite 4-MAA in serum was determined in seven horses of different breeds after a single intravenous dose administration. A biexponential formula was fitted to the serum concentration vs. time data. The median half-life of the elimination phase (t1/2 beta) was 4.85 h (range 5.04 h), the median volume of distribution (Vd(area)) was 1.85 L/kg (range 3.2 L/kg) and median of total clearance was 4.0 mL/min/kg (range 2.3 mL/min/kg).

Animals↗
PubMed1997

[Kinetics of elimination of diazepam after intravenous injection in horses].

Diazepam is used in veterinary medicine as sedative and pre-anaesthetic agent. This publication describes the plasma-concentration time curve for diazepam and its metabolite in horses suffering from colic after intravenous application as pre-anaesthetic agent. Elimination half-life (t1/2 beta) after a dose of 0.05-0.08 mg/kg (30-50 mg Diazepam per horse) was 7.5 to 13.2 h. Total clearance (Cltot) between 1.86 and 3.44 ml/min/kg was detected and apparent volume of distribution in steady state (Vdiss) was 1.98 to 2.25 l/kg. Diazepam was still found in serum after 24 h. The metabolite oxazepam could be found in plasma. Its elimination half-life was 14-16.5 hours.

Adjuvants, Anesthesia↗
PubMed1996

[The modification of the effects of calcium on the heart using beta-adrenergic blockers].

To reduce unwanted effects of calcium upon the heart, in particular in cows during the treatment of hypocalcaemia, experiments were carried out in isolated hearts of guinea pigs and in conscious rabbits, to show whether beta-adrenergic blocking agents are able to antagonize these effects. It was found that calcium effects in the second phase which is characterized by a tachycardia, are antagonized by carazolol, which was used for these experiments.

Adrenergic beta-Antagonists↗
PubMed1996

[Natural and synthetic glucocorticoids in the racing horse: a review of the literature].

This review compromises data about endogenous cortisol and its physiological variations in horses. The influence of synthetic glucocorticoids on the endogenous cortisol concentrations is discussed as well. The second part of the review summarizes detection times of therapeutically used glucocorticoids (dexamethasone, betamethasone, triamcinolone, prednisone, prednisolone, methylprednisolone and hydrocortisone) in the horse and their implication for doping control.

Animals↗
PubMed1995

Comparative toxicity of Ricinus communis and Jatropha curcas in Brown Hisex chicks.

Symptoms, lesions and changes in growth, haematology and clinical chemistry were investigated in Brown Hisex chicks fed diets containing 0.5% Jatropha curcas seed or 0.5% Ricinus communis seed. High mortality and more severe changes occurred in chicks on Ricinus diet than Jatropha feed. The results indicated that caution should be observed in tropical countries where people are accustomed to chewing castor bean when in need of a laxative.

Animal Feed↗
PubMed1995

The effect of praziquantel on the activities of some drug-metabolizing hepatic enzymes in rabbits.

The effect of oral administration of praziquantel at different dose levels on the activities of metabolizing hepatic enzymes (aminopyrine N-demethylase, aniline 4-hydroxylase and UDP-glucuronyltransferase) was studied in healthy locally bred rabbits. The pathological changes resulting from drug's toxicity were assessed histologically, by measurement of total plasma protein concentration and of the activities of the plasma enzymes sorbitol dehydrogenase (SD), glutamate dehydrogenase (GD) and aspartate aminotransferase (AST). No significant changes were obtained after praziquantel administration at dose levels of 40 and 800 mg/kg body weight, whereas 1600 mg/kg and 2000 mg/kg of praziquantel resulted in a significant decrease in the activities of the three drug-metabolizing hepatic enzymes under investigation in the livers of treated rabbits. All rabbits which received praziquantel at the dose rate of 2000 mg/kg died 10-20 hours following praziquantel treatment.

Administration, Oral↗
PubMed1995

[Pharmacological effects of hordenine].

Hordenine is an ingredient of some plants which are used as feed for animals, i.e. in sprouting barley. After ingestion of such feed hordenine may be detected in blood or urine of horses which in case of racing horses may be the facts of using prohibited compounds. Results of some experiments in pharmacological models show that hordenine is an indirectly acting adrenergic drug. It liberates norepinephrine from stores. In isolated organs and those structures with reduced epinephrine contents the hordenine-effect is only very poor. Experiments in intact animals (rats, dogs) show that hordenine has a positive inotropic effect upon the heart, increases systolic and diastolic blood pressure, peripheral blood flow volume, inhibits gut movements but has no effect upon the psychomotorical behaviour of mice. All effects are short and only possible after high doses which are not to be expected after ingestion of hordenine containing feed for horses. A measurable increase of the performance of racing horses is quite improbable.

Alkaloids↗
PubMed1995

Deposition kinetics, metabolism and urinary excretion of sulfathiazole following oral administration in sheep.

Deposition kinetics, metabolism and urinary excretion of sulfathiazole were investigated in German black head sheep following single oral administration (100 mg/kg). Kinetic evaluation of plasma levels was performed using a two-compartment best fit model. Sulfathiazole is significantly metabolized to N4-acetyl metabolite in the rumen fluid. The drug is very poorly absorbed since the minimum effective concentration in plasma was not attained at any time following oral administration. The prolonged elimination half-life in sheep may be due to a low rate of drug absorption from the rumen and gastro-intestinal tract. Sulfathiazole was mainly excreted in the urine as free drug and N4-acetyl metabolite.

Administration, Oral↗
PubMed1995

In vitro metabolism of sulfathiazole in rumen fluid and its metabolism and disposition kinetics following intraruminal administration in sheep.

The antimicrobial agents may undergo a change in the complex stomach particularly in the rumen as a result of microbial fermentation in ruminants. Present investigation deals with the influence of ruminal fluid probably the role of ruminal microorganisms on the degradation of sulfathiazole in vitro and its metabolism and disposition following its single intraruminal administration (100 mg/kg) in adult german black head sheep. Sulfathiazole is metabolized to N4-acetyl sulfathiazole in the rumen fluid after its in vitro incubation at different concentrations (10-60 micrograms/ml) for varying time intervals (1-6 h) at a temperature of 38 +/- 0.5 degrees C. Likewise in vivo it is significantly metabolized to its N-acetyl metabolite in the rumen after an intraruminal administration. The levels of sulfathiazole are maintained above minimum effective therapeutic concentration (40 micrograms/ml) for more than 24 h in rumen fluid. The drug is poorly absorbed into the circulation after intraruminal administration since the levels in plasma could not reach up to minimum effective therapeutic concentration at any time. The biological half-life of sulfathiazole was found to be 16.7 h following single intraruminal administration. Results of this investigation suggest that oral or intraruminal application of sulfathiazole has only local effects in the rumen fluid. A systemic treatment is not possible after this path of application.

Animals↗
PubMed1994

[Decrease of the lead burden of cattle within the last 20 years].

After introduction of many measures in technical and hygienic fields, emission of lead was remarkably reduced within the last years. Whether these measures were followed by a real decrease of the actual lead burden of man and animals may be recognized by controlling the lead content of food. Further it was possible to quantify a biological effect as an indicator of lead burden by the activity of delta-aminolevulinic acid dehydratase in red blood cells of cows in the Hannover area and to compare actual results with those obtained twenty years ago in the same region using identical methods. Results show a remarkable decrease of lead-caused inhibition of that enzyme.

Aminolevulinic Acid↗
PubMed1994

[Doping problems in horse sports--pharmacokinetics of selected antiphlogistics/analgesics relevant to doping].

Drug treatment of horses which are used in horse-racing is restricted by the regulations of the anti-doping control. Veterinarians and anti-doping control commissions are faced with the problems resulting from the discrepancy between the demand "no drugs in blood/urine of horses at the time of competition" and the need for treatment. The pharmacokinetic data of important antiphlogistics/analgetics (NSAID) for horses given in this article shall facilitate the decision of the veterinarians and commissions whether a horse having been treated with NSAID may participate in a competition or not. Further a new concept of anti-doping regulation of therapeutic substances is presented for discussion.

Animal Welfare↗
PubMed1994

[Delayed effects of calcium].

Some extracardial effects of a calcium chloride solution were analysed for a period of one week after infusion in cattle, sheep and rabbits. Effects upon the heart occur during the infusion or immediately after it (peracute calcium toxicity) and are related to a hypercalcaemia. They consist in disturbances of some metabolic processes, in particular of the skeletal musculature (myopathia). Marked increases of the activities of creatin-kinase of the serum show delayed effects of calcium, which are dose dependent. During the time of maximal effects the calcium concentrations in the serum of treated animals are normal. So the situation can be called a toxic normocalcaemic (post-hypercalcemic) calcium effect. An additional application of calcium in a large dosage within a period of 72 hours after the first application may increase the toxic effects of calcium.

Animals↗
PubMed1994

[Veterinary public health--neglected education].

The international term Veterinary Public Health (VPH) can not be translated into other languages. It covers all measures for safeguarding of animal health including animal welfare and food producing efficiency and finally the protection of human health. Actual changes of the structure of animal producing systems and the easy movements of animals from one place to another, the use of chemical compounds with pharmacological effects (like veterinary drugs and growth promotors) and the occurrence of environmental pollutants require new chief stress for veterinary service in particular for farm animals. Protection of man, animal and environment against harmful influences, control of cummunicable diseases, protection of man and environment against influences from livestock breeding including wastes and carcasses, increase of efficiency and quality of food production and finally the care of animal welfare under the influence of man require other strategies than the treatment of diseased animals or flocks. This should be considered for education systems of graduates and postgraduates by coordination of traditional subjects and introduction of Epidemiology, Ecology and Environmental Hygiene into the veterinary syllabus.

Animals↗
PubMed1993

By toxic effects of the dried leaves and stem of Capparis tomentosa on Nubian goats.

Nubian goats were given single or repeated dosages of 5, 2.5 and 0.25 g/kg of dried leaves or stem of C. tomentosa by drench and died or were slaughtered at various times post-dosing. One goat receiving Capparis stem at 2.5 g/kg on every other day basis for 8 days developed signs of toxicosis and recovered following cessation of plant administration. The prominent features of toxicity were inappetence, locomotor disturbances, paresis especially of the hind limbs and recumbency. Lesions comprised perineuronal vacuolation in the gray matter of the spinal cord at the sacral region, centrilobular hepatocellular necrosis, degeneration of the renal proximal convoluted and collecting tubules, serous atrophy of the cardiac fat and renal pelvis and straw-coloured fluid in serious cavities. In Capparis-fed goats, anaemia developed and the results of kidney and liver function tests were correlated with clinical abnormalities and pathologic changes.

Animals↗
PubMed1993

A hundred years of the Deutsche Tierärztliche Wochenschrift.

Some reports of veterinary societies were issued in the second half of the 19th century in Germany. Dr. med LYDTIN in Karlsruhe (Baden) tried to unify two local reports to found a new journal with a widespread distribution. The first issue of the "Deutsche Thierärztliche Wochenschrift" was published on 7th January 1893 in Karlsruhe. To increase the area of distribution some years later a professor from the School of Veterinary Medicine Hannover was invited to work as an editor of this journal. After 1897 the DTW was issued in Hannover in close cooperation with the School of Veterinary Medicine. So the DTW is the oldest German veterinary journal which was issued continuously with an unchanged name since 100 years.

Germany↗
PubMed1992

[Veterinary medicine and environmental hygiene--20 years of seminars on environmental hygiene].

The changes of the environment after industrialization since 1965 influenced some political decisions concerning a critical evaluation of such development which may injure the environment. The School of Veterinary Medicine Hannover discussed in that time how the problems could be met by establishing a postgraduate stadium of environmental sciences. These ideas were realized, starting with seminars in the first year for one week, later for one or two days periods (Table). Postgraduate students and interested veterinarians with questions arising from their occupation participated in the seminars. The main topics of the seminars referred to effects of chemical, physical and biological influences from the environment upon farm animals and vice versa that part of animal housing which is involved in the harmful changes of the environment.

Agriculture↗
PubMed1992

[Effects of dopamine on the coronary vessels of swine].

The pharmacological responses of dopamine, a catecholamine which is used as a circulatory active drug in shock treatment, were investigated in isolated coronary arteries of pigs from the slaughter house. The effects are compared with those obtained after application of adrenaline and noradrenaline in the same in vitro system. The aim of the experiments was to discover whether the three catecholamines have an effect on the same adrenergic receptors and to characterize the specific effect of dopamine. Phentolamine and propranolol were used as adrenergic alpha- und beta-blockers, azaperone and haloperidol were used as unspecific antagonists, and domperidone as a specific dopamine antagonist. The three catecholamines caused a dose-dependent vasodilation of the coronary artery. A pretreatment of the vessels with phentolamine did not affect the vasodilation after all three catecholamines. Propranolol inhibited the effects of only adrenaline and noradrenaline, but not those of dopamine. Azaperone, haloperidol and domperidone were effective to inhibit the dopamine-action, but not those of adrenaline and noradrenaline. The results show, that the vasodilation of the coronary artery by dopamine is not related to a stimulation of adrenergic alpha- oder beta-receptors. Adrenaline and noradrenaline produce a vasodilation only by a stimulation of adrenergic beta-receptors, as alpha-receptors are not present in the coronary system of the pig. The conclusion is that the vasodilation of the coronary artery is caused by a stimulation of specific dopaminergic receptors. The coronary effects of dopamine in shock therapy are reduced after a treatment of the animals with butyrophenone derivatives like azaperone or haloperidol or after treatment with the specific dopamine antagonist domperidone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗