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Biomedical subjects

P Hoffmann

Publications and source records attributed to P Hoffmann.

At least 217 records · Page 12Linked to original sources
PubMed1987

Effect of voluntary exercise on open-field behavior and on aggression in the spontaneously hypertensive rat (SHR).

In the present study we investigated the influence of voluntary exercise on exploratory behavior and on aggression in the spontaneously hypertensive rat (SHR). Twenty-four SHR (8 weeks old) were randomly assigned to either an exercise group or a sedentary control group. The animals in the exercise group exhibited a spontaneous wheel running activity of 5-6 km/day during 6 weeks. The characteristic hyperexploratory behavior of SHR was lowered in the exercise group (p less than .001) as compared to the control group. The runners also showed a tendency for less aggression. In the postexercise period, when the runners' wheels were locked, the exercise group had a significant rise in aggression (p less than .01) vs the controls. The exploratory behavior returned immediately to the level of the controls, but we found no further increase in any of the parameters measured. However, the runners showed a type of displaced aggression exhibited as digging and biting in the test cage. This evidence suggests that voluntary exercise lowers the hyperexploratory behavior and aggression in the SHR and that an abrupt stop in exercise gives an "abstinence" reaction.

Aggression↗
PubMed1987

Effect of spontaneous running on blood pressure, heart rate and cardiac dimensions in developing and established spontaneous hypertension in rats.

The effect of chronic voluntary exercise on resting blood pressure and heart rate was measured in two different age groups of spontaneously hypertensive rats (SHR). In the younger group, left ventricular dimensions were also measured. The younger group was 9 weeks old at the start of the experiment and was in a period of rapid blood-pressure rise. The older group, 13 weeks old at the start of the experiment, already had established hypertension. During a period of 6 weeks, the animals ran spontaneously in wheels mounted in their cages and reached a maximum of 6-7 km per 24 h. Age-matched, sedentary SHR were used as controls. Both groups of runners showed a decrease in body weight in comparison to controls. The younger runners exhibited a delayed onset of hypertension. They also showed a significantly increased left ventricular (LV) end-diastolic volume for every measured end-diastolic pressure between 7.5 mmHg and 20 mmHg (P less than 0.05). This suggests the development of a structural growth-dependent increase of the internal LV radius while LV weight and wall-to-lumen ratio were largely unaltered in younger runners compared with controls. In SHR with established hypertension, physical training did not reduce arterial blood pressure but heart rate was significantly lower than in the controls. These results thus indicate that an early onset of physical exercise in SHR may delay the development of hypertension. In addition, a more favourable cardiac design could also be seen.

Age Factors↗
PubMed1987

What about the effects of dietary lipids on endogenous prostanoid synthesis? A state-of-the-art review.

The endogenous prostanoid synthesis can principally be influenced by a variation of the polyunsaturated fatty acid supply in food. Withholding an essential fatty acid supply in food for a length of time results in a low rate of formation of prostanoids. However, there is no simple correlation between the amount of prostaglandin precursor fatty acid supplied with food and the biosynthesis of prostanoids in the different organs. A progressive increase of the intake of polyunsaturated fatty acids results in irregular changes in the prostanoid synthesis of the organism. The impact of various parameters should be taken into account, e.g., the period of feeding, the preexperimental state of the organism, the kind of polyunsaturated fatty acid related to a particular family of fatty acids, interactions with other components of food, differences of the species, organ specificities, aspects of chronoperiodicity, interactions of the prostanoids (and polyunsaturated fatty acids, respectively) with other metabolic circuits on a different level of integration, and details in the methods applied in the determination of prostanoids. Above all, care must be taken to prevent too general conclusions being drawn about the influence on the endogenous synthesis of prostanoids by dietary polyunsaturated fatty acids.

Animals↗
PubMed1986

Comparative study of the blood pressure effects of four different vegetable fats on young, spontaneously hypertensive rats.

Following the suckling period, four groups of male four-week-old spontaneously hypertensive rats (SHR) were fed semisynthetic diets with 14% (by weight) of either sunflower seed oil [46% 18:2(n-6); linoleic acid (LA)-rich], linseed oil [62.5% 18:3(n-3) + 12.9% 18:2(n-6); alpha-linolenic acid (LNA)-rich], evening primrose oil [9.2% 18:3(n-6) + 71% 18:2(n-6); gamma-linolenic acid (LNA)-rich] or hydrogenated palm kernel fat [1.5% 18:2(n-6); polyunsaturated fatty acid (PUFA)-deficient], respectively, up to an age of 18 wk. All diets enriched with PUFA provoked an attenuation of hypertension development. The effect was lowest in the LA-rich group and highest in the gamma-LNA-rich group. Differences in fatty acid composition of renal phospholipids between groups reflect the fatty acids present in the respective dietary fats. Renomedullary production of PGF2 alpha was significantly reduced in alpha-LNA-rich and slightly diminished in gamma-LNA-rich fed rats. Aortic formation of 6-keto-PGF1 alpha and TXB2 was increased in animals fed the gamma-LNA-rich diet. Thus, the attenuation of hypertension development cannot be explained only by changes in prostanoid formation. Other mechanisms possibly involved should be pursued.

Animals↗
PubMed1986

Circadian rhythm of eicosanoid formation as affected by dietary linoleate.

Circadian rhythms of eicosanoid formation were investigated in linoleic acid (LA) rich (sunflower seed oil, 13.3 cal% LA) and LA deficient (hydrogenated palm kernel fat, 0.5 cal% LA) diet fed male Wistar rats adapted to an artificial lighting regimen of 12 hours light and 12 hours darkness. Over a period of 24 hours we examined at 4 hour intervals eicosanoid formation in the aorta (PGI2, PGE, PGF2 alpha), in the heart (6-keto-PGF1 alpha, PGE, PGF2 alpha, TXB2), in the kidney (PGE, PGF2 alpha) and in the brain (PGE, PGF2 alpha). Two types of circadian variation curves were observed: Low eicosanoid formation in the light period and increase in the dark cycle (PGE in aorta and heart, TXB2 in heart). The increase in eicosanoid formation in the dark cycle was diminished after an LA deficient diet. Continuous decrease (PGI2 in aorta) and increase (PGE in the brain), respectively, in the course of the day, without differences between the two dietary groups. We assume that the circadian oscillations of eicosanoid formation might be of importance for the development of the circadian time structure of the organism.

Animals↗
PubMed1986

Serum triglycerides and HDL cholesterol from SHR after evening primrose oil and other polyunsaturated fats.

Spontaneously hypertensive rats (SHR) were fed diets enriched with evening primrose (EPO), sunflower (SO) and linseed oils (LO) as well as palm kernel fat (PKF), the latter being deficient in polyunsarated fatty acids (PUFA). In SHR fed EPO serum triglycerides were lowest and HDL1 cholesterol was highest as compared to the other groups of animals. Total cholesterol was not different. The data suggest that - as with blood pressure - serum lipids and lipoproteins might be influenced most effectively by EPO in comparison to other polyunsaturated fats.

Administration, Oral↗
PubMed1986

Antihypertensive effect of dietary sunflowerseed oil and linseed oil in spontaneously hypertensive rats during a multigeneration feeding study.

Semisynthetic diets enriched with polyunsaturated fatty acids (30 en% sunflowerseed oil or linseed oil) reduced hypertension development in spontaneously hypertensive rats (SHR) compared with control SHR fed on a regular rat chow. The effect was most markedly expressed in the 3rd and 4th generations of a four generation feeding period. PGI2-like production from isolated, pulsatingly perfused aorta preparations was reduced in linseed oil but not in sunflowerseed oil fed rats. Effects on blood pressure and PGI2-like production were abolished when the semisynthetic diets were changed for regular chow (5th and 6th generations).

Animals↗
PubMed1986

Cardiovascular actions of dietary polyunsaturates and related mechanisms. A state-of-the-art-review.

A survey of the effects of dietary polyunsaturates on the function of the cardiovascular system is given. In isolated hearts of rats dietary linoleate supply increases both coronary flow and heart muscle function. Hearts of rats fed high amounts of linoleic acid are protected against catecholamine (over)-stimulation. Polyunsaturate rich vegetable oils are effective in lowering blood pressure in several murine hypertension models. This effect seems to be closely related to antihypertensive changes in kidney function and in the function of the arterial vessel wall. Dietary polyunsaturates augment the hypotensive effect of antihypertensive drugs. Cardiovascular effects of dietary polyunsaturates are at least partly mediated via changes in the prostanoid metabolism as well as a reduction of the sympathetic activity. Evidence has been accumulated that cardiovascular effects of dietary polyunsaturates in animal and man are comparable. The observed effects are discussed against the background of a reduced risk of cardiovascular disease after a polyunsaturate rich diet in man.

Animals↗
PubMed1986

Long-lasting cardiovascular depression induced by acupuncture-like stimulation of the sciatic nerve in unanaesthetized rats. Effects of arousal and type of hypertension.

Prolonged low frequency stimulation of the sciatic nerve in conscious spontaneously hypertensive rats (SHR), is reported to induce a naloxone-reversible long-lasting depressor response (Yao et al. 1982a). In the present study this depressor response was compared during daytime and night-time conditions to determine whether different degrees of arousal affect this response. In addition, the effect of sciatic nerve stimulation was examined in one-clip, two-kidney renal hypertensive rats (RHR); a type of secondary hypertension which lacks the central autonomic hyper-reactivity which characterizes the SHR variant of primary hypertension. A maximal fall in blood pressure of 20 mm Hg was observed 1 h after sciatic nerve stimulation in SHR examined in daytime. We also found a significant bradycardia that lasted for 2.5 h. Neither poststimulatory depression nor bradycardia were observed in RHR examined at daytime. A short-lasting, non-significant decrease in blood pressure and heart rate was found following sciatic stimulation in SHR examined at night.

Acupuncture Therapy↗
PubMed1986

[Omphalocele and gastroschisis: problems in intensive medical treatment].

Aetiologically and pathognomically, omphalocele and gastroschisis are different forms of occlusive disorders in the anterior abdominal wall of newborns. Their prognosis has clearly improved in recent years, owing to progress in surgical and conservative treatment, primarily on account of improved intensive medical care of the children concerned. Courses and survival rates of newborns with either malformation have proved to depend strongly on the initial condition of the patients. The authors' own studies, in agreement with most of the literature, have shown that the incidence of severe syndromes of malformation has been comparatively high among newborns with omphalocele, whereas children with gastroschisis are usually small-for-date newborns with low birth weight. This has been a frequent limitation to successful treatment. Major importance, in terms of intensive medical treatment, should be attributed to postoperative completely parenteral feeding, throughout the early postsurgical phase during which the patient is particularly endangered from recurrent disorders of passage, as well as to artificial respiration due to respiratory constraint on account of elevated diaphragm and disproportionality between the abdominal cavity and retroposed viscera. Early administration of amino acids, carbohydrates, fat, trace elements, immunoglobulins, and vitamins, with doses being systematically increased by a prespecified pattern, has proved to be necessary to counteract catabolism accompanied by somewhat severe disorders in wound healing, subacute obstruction, and massive attacks of septic infections. This is possible only through central venous catheterization. Resulting thrombotic or septic complications may be mitigated by partial heparinization of the children.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1986

Cardiovascular actions of dihydralazine as modified by dietary linoleic acid.

The experiments were carried out in order to examine whether the hypotensive effect of dihydralazine can be augmented by concomitant ingestion of a diet enriched with linoleic acid. After prefeeding with a linoleic acid rich diet (13.3 J%) an augmented hypotensive dihydralazine effect (11-24 mm Hg) could be observed in acute experiments in conscious (1 mg/kg i.v.) and pentobarbital-anaesthetised (4 mg/kg i.v.) normotensive rats with different duration of the feeding period as well as in conscious (1 mg/kg i.v.) spontaneously hypertensive rats relative to linoleic acid poor (0.5 J%) fed animals. This effect was abolished by pretreatment with the cyclooxygenase inhibitors indomethacin (10 mg/kg i.v.) or acetylsalicylic acid (100 mg/kg i.v.). The chronotropic dihydralazine response was with one exception not different between the two dietary groups. In chronic experiments with spontaneously hypertensive rats the augmentation of the hypotensive dihydralazine effect (1 mg/kg X d, s.c.) after linoleic acid rich diet did not attain statistical significance after a 6-weak prefeeding period. The renovasodilatory action of dihydralazine (3 mg) was increased in isolated kidney preparations of linoleic acid rich fed rats. This effect was accompanied by a shift of the prostaglandin formation toward vasodepressive PGE. We conclude that the altered cardiovascular effects of dihydralazine after linoleic acid rich diet are primarily caused by changes in the formation of prostaglandins and the activity of the sympathetic nervous system.

Animals↗
PubMed1986

[Intracranial pressure and circulatory parameters with positive end-expiratory pressure (PEEP). The possibility of drug modification].

In patients who have head injuries as well as injuries involving other organ systems, especially those of the thorax and upper abdomen, conflict can arise between the need to ensure adequate ventilation and the simultaneous need to protect the brain against further increases in intracranial pressure. Positive end-expiratory pressure (PEEP) ventilation, in particular, is suspected of causing the intracranial pressure to rise. Our study of the effects of a combination of anaesthetics on animals, was designed to investigate whether, the negative effects of PEEP ventilation on both intracranial pressure and on various circulatory parameters could be prevented. In animals with normal intracranial pressure at the outset of the experiment, during PEEP ventilation at pressures of up to 12 cmH2O, neither clinically significant rises in intracranial pressure, nor notable changes in circulatory parameters occurred. In comparison, those animals with artificially raised intracranial pressure showed marked differences with respect to their tolerance of PEEP ventilation. Whereas ventilation with an oxygen/nitrous oxide mixture caused a distinct elevation of the intracranial pressure and the deterioration of circulatory parameters, a combined regimen of etomidate and alfentanil under ventilation with an oxygen/air mixture minimized the negative effects of PEEP. Gradual increases in PEEP were tolerated better than a rapid rise in PEEP. With appropriate drug therapy, it is therefore possible to maintain PEEP ventilation in the presence of raised intracranial pressure without causing deterioration of the circulatory situation, or exacerbating the problems of intracranial pressure or cerebral perfusion pressure.

Anesthesia↗
PubMed1985

Pirenzepine versus cimetidine in duodenal ulcer treatment. A clinical and microbiological study.

The therapeutic efficacy of pirenzepine (PIR) and cimetidine (CIM) in duodenal ulcer and their effects on the intragastric milieu have been studied in a double-blind multicentre trial. Seventy-nine patients with endoscopically proven duodenal ulcer were randomly allocated to 4 weeks' treatment with either 50 mg PIR twice daily or 400 mg CIM twice daily. In addition to clinical and endoscopic evaluation and registration of side effects and laboratory test results, endoscopically obtained gastric juice was cultured and its nitrite concentration was measured before and at the end of the treatment. Seventy-five patients completed the study. The treatment groups were comparable with regard to age, sex, smoking habits, and consumption of coffee and alcohol. After 4 weeks, 27 of 37 patients (73%) in the PIR group were completely healed, compared with 29 of 38 (76%) in the CIM group (NS). The number of patients with side effects was similar in both groups, but side effects of antimuscarinic type were more frequently reported by patients in the PIR group. Intragastric microbial concentrations increased significantly during treatment in both groups but remained well within normal limits. No single nitrite concentration before or after treatment exceeded the normal range. In conclusion, the two drugs were about equally effective in the short-term treatment of duodenal ulcer disease. In the doses given they did not adversely affect the intragastric milieu.

Aged↗
PubMed1985

Low density lipoproteins of male donors decrease prostacyclin (PGI2) and enhance thromboxane (TXA2) release from rat aortas perfused under pulsatile pressure.

The influence of low density lipoproteins (LDL)-cholesterol (1.69 +/- 0.08 mg/ml) and of high density lipoproteins (HDL)-cholesterol (0.62 +/- 0.09 mg/ml), respectively, on the levels of 6-oxo-PGF1 alpha and TXB2 in the perfusates of rat aortas perfused under pulsatile pressure was studied. After passage through the aortas the concentration of LDL-cholesterol was significantly decreased in the perfusates, whereas the HDL-cholesterol level was unchanged. In comparison to controls, perfused with lipoprotein free solution, the concentration of 6-oxo-PGF1 alpha was significantly decreased more than 50% by LDL and the TXB2 level was enhanced significantly by approximately 50%. This results in a significant rise of the TXB2/6-oxo-PGF1 alpha ratio in the perfusates. HDL did not significantly change the ratio of these eicosanoids in the perfusates. These results suggest that this concentration of LDL enhanced the formation of the proaggregatory TXA2 and decreased the formation of the antiaggregatory PGI2 in rat aortas perfused under pulsatile pressure. The proaggregatory action of an elevated level of LDL during the development of atherosclerosis in men may be also mediated by changes in the metabolism of eicosanoids of the vessel wall.

Animals↗
PubMed1985

[Alfentanil for neuroleptanesthesia in short operations].

Alfentanil, a potent short acting analgetic, is used for short operations instead of fentanyl as a neurolept anaesthesia agent. The action of this form of anaesthesia is described. As initial dose of alfentanil we used 25 micrograms/kg b.w. The total dose of alfentanil for operations of about 30 min on average was 40 micrograms/kg b.w. Blood pressure, heart rate and side effects of this form of anaesthesia have been investigated.

Adolescent↗