ISSN:0014-312X    

DOI:10.1159/000128612

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Electrophysiologic effects of acetylcholine (Ach) injections were compared to those obtained by vagus stimulation with and without β-adrenoreceptor blockade during right heart catheterization in 12 dogs. Monophasic action potentials were obtained by suction electrode technique, and programmed electrical stimulation was used to determine heart rate independent changes in 50 and 90% repolarization times and the effective (V-FRP) and functional (V-FRP) refractory periods of the right ventricle. Vagus stimulation decreased heart rate with and without β-blockade, while after Ach injections a marked increase in heart rate was found, which could be eliminated by β-blockade. Vagus stimulation increased action potential duration and refractoriness at high sympathetic tone induced by pentobarbital anesthesia, mainly by inhibiting the effect of β-adrenoreceptor stimulation. It is concluded that stimulation of the vagus induces antiarrhythmic effects at high sympathetic activity, while the change in ventricular electrophysiology found after Ach injections in high doses to intact animals is an effect probably induced by stimulation of β1-recep

ISSN:0014-312X    

DOI:10.1159/000128614

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

To evaluate the strain on a sutured Achilles tendon during walking in a short leg cast the EMG activity of the triceps surae muscles was studied. The regression line of the EMG/torque relationship of the triceps surae in the noninjured leg was investigated during isometric contractions with the foot in the same plantarflexed position as the injured foot immobilized in plaster cast. A linear relationship was found between EMG activity (EMG signals converted to rectified mean square values) and torque, measured with Cybex II. The torque provided by the triceps surae of the injured leg was calculated from the registered EMG activity during walking and the regression line. The strain acting on the sutured Achilles tendon was calculated after measurement of the lever arm. There was no significant difference in calculated strain on the sutured Achilles tendon during nonweight bearing in a short leg cast and full weight bearing without external rotation movement of the leg. External rotation movement of the leg during full weight bearing gave increased strain on the sutured Achilles tendon. The actual strain is considered somewhat lower than the calculated one since other muscles than the triceps surae contribute to plantar flexion of the ankle joint. The results indicate that the strain during weight bearing in a short leg cast is unlikely to exceed the strength of a sutured Achilles tendon.

ISSN:0014-312X    

DOI:10.1159/000128616

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The arterial oxygen tension of diving seals decreases to values as low as 1.33 kPa at the end of prolonged dives. In spite of this, cardiac function is unimpaired due to a profound reduction of myocardial oxygen demands: Heart rate is immediately reduced some 90%, left ventricular dP/dt(max) is reduced some 25%, and ventricular wall tension is slightly reduced. This reduction of myocardial workload even allows coronary blood flow to be reduced some 90% and a significant proportion of myocardial energy expenditure to be covered by anaerobic metabolism based on endogenous stores of glycogen. It is suggested that the myocardial ischaemic defence, as worked out by nature herself, in the diving seal has important implications for the treatment of acute myocardial ischaemia in man.

ISSN:0014-312X    

DOI:10.1159/000128617

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The tosional behaviour of the femur has been studied in 145 male Wistar rats, aged 3–36 weeks. The ultimate torsional moment and the torsional stiffness of the femora increased with increasing animal age. In contrast, the femoral deformation at failure, the ultimate torsional angle, was almost constant for all age levels. The strength and stiffness of cortical bone as a material, the ultimate torsional stress and the modulus of rigidity reached a plateau when the rats were about 14 weeks old, and had a body weight and femoral length of about 350 g and 35 mm, respectively. In conclusion, cortical bone of Wistar rats probably reaches maturity at an age of about 14 wee

ISSN:0014-312X    

DOI:10.1159/000128618

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Of 12 patients admitted for percutaneous retrieval of retained biliary stones through a postsurgery T-tube tract, 10 patients were successfully treated. The method using catheter technique and Dormier basket is reviewed.

ISSN:0014-312X    

DOI:10.1159/000128619

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Subcapital cadaveric femoral neck osteotomies were internally fixed either by a compression hip screw and a lag screw or by two von Bahr screws. The specimens were then subjected to mechanical testing. Continuously increasing axial compression loads were applied on the femoral head until failure and simultaneously the displacement of the osteotomies was measured. With loads up to 2 kN (about 3 times the body weight) no differences were found between the two groups in the displacement of the osteotomies.

ISSN:0014-312X    

DOI:10.1159/000128620

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The present study characterizes the immunological and biological activity of circulating forms of parathyroid hormone (PTH) in patients with primary hyperparathyroidism. In addition, the rate of elimination of intravenously injected 125I-labelled bovine parathyroid hormone (125I-bPTH) was studied in patients with this disease before and after operation. The different molecular forms of serum PTH were characterized by gel chromatography followed by radioimmunoassay employing two antisera with specificities directed against the N-terminal and mid-region part of the peptide, respectively. The major part of immunoreactive PTH (iPTH; on the average above 50%) eluted corresponding to fragments with a molecular size about 7,500 daltons in both radioimmunoassays. Specific immunoreactivity coeluting with the intact hormone represented 9–15%. The biological activity of hyperparathyroid serum after gel chromatography was tested in a hormone-sensitive rat kidney adenylyl cyclase assay system. The basal and PTH-stimulated adenylyl cyclase activity (half-maximal stimulation at 5 µg/l or 0.6 nM) was dependent on Mg2+ and ATP. Maximal responses to PTH, calcitonin, and prostaglandin E2 were 50–200% above basal activity and were obtained in the presence of both GTP and Gpp(NH)p (5 × 10-4M). Serum from patients with hyperparathyroidism and PTH extracted from parathyroid tissue stimulated the adenylyl cyclase in a dose-dependent manner, as did the chromatographic fraction representing the intact hormone. Elimination of 125I-bPTH from circulation after intravenous injection to patients with this disease suggested that the hormone, but not its degradation products, were removed more rapidly before than after successful surgery. We conclude that the major part of circulating iPTH in patients with primary hyperparathyroidism is unable to stimulate the rat kidney adenylyl cyclase, and that the biological PTH activity is represented by the intact hormone (15% or less of total iPTH). These patients degrade more rapidly the injected 125I-bPTH and this mechanism introduces a new concept to protect target cells against excessive hormone a

ISSN:0014-312X    

DOI:10.1159/000128621

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

The effect of H2-stimulation and blockade was studied in a dog model which made possible physiological stimulation by food and comparison of vagally innervated and denervated acid and pepsin response at the same time. 5 dogs were equipped with two pouches separated from the stomach, and stimulation was done by histamine as continuous infusion combined with a standard meal – a mixture of liver, heart and bonemeal, 10 g/kg. The response was compared with the effect of H2-blockade, cimetidine 5 g/kg, given 30 min before the meal. H2-agonism stimulated acid secretion and strongly inhibited pepsin secretion, and when H2-antagonism was applied, the effects were quite opposite. The results may explain the great differences in acid and pepsin secretion seen after H2-blockad

ISSN:0014-312X    

DOI:10.1159/000128622

出版商:S. Karger AG    

年代:1984

数据来源: Karger

摘要:

Low density lipoprotein (LDL) is a risk factor in the development of atherosclerosis. The biological mechanism for this association has been obscure. This paper shows that LDL can be modified in vitro by several chemical and biological means. Modified forms of LDL seem to make it susceptible to enhanced uptake in macrophages. LDL may also induce disturbance of the surrounding cells, especially endothelial cells, as it is potentially cytotoxic. An hypothesis is presented based on the fact that LDL is a labile lipoprotein and may, while situated in the arterial wall, undergo modifications and thereby lead to lipid deposition.

ISSN:0014-312X    

DOI:10.1159/000128623

出版商:S. Karger AG    

年代:1984

数据来源: Karger