Intramyocardial temperature following various cooling procedures

In 12 dogs on cardiopulmonary bypass, the intramyocardial temperatures in the anterior and the posterior wall of the left ventricle and in the septum were measured with microthermoelectrodes when different cooling procedures were used during 60 min of anoxic cardiac arrest. External cooling with 4 degrees C glucose (5.5%) solution dripping into the pericardial sac did not lower the temperature in the septum or in the posterior wall. Packing the heart in slushed ice after injection of the same glucose solution into the coronary tree reduced the septum and posterior wall temperature to around 30 degrees C. This cooling procedure, in combination with general moderate hypothermia, lowered the temperature to about 20 degrees C in these parts of the heart. Only when combined with general hypothermia did local cooling achieve low temperatures in all regions of the myocardium.

Myocardial preservation during anoxic arrest. Premedication with propranolol, verapamil or methylprednisolone

Anoxic cardiac arrest was studied for one hour in five groups of dogs. Groups I-III were given methylprednisolone (30 mg/kg b.w.) before aortic cross-clamping. Normothermia was used with electrically induced ventricular fibrillation in group I, and without such fibrillation in group II, while group III was studied in local hypothermia. Propranolol (10 micrograms/kg) was given to group IV and verapamil (0.2 mg/kg) to group V before the anoxic arrest in local hypothermia. Judged from the ability of the heart to take over the circulation after anoxic arrest, local cooling preceded by propranolol or verapamil gave working performance comparable with the pre-arrest values. In the cooled, steroid-pretreated hearts the work capacity was depressed to the same degree as in locally cooled hearts without steroid premedication. Methylprednisolone prevented ischemic contracture during normothermic arrest with induced fibrillation, but not in the absence of such fibrillation. As adjuvant to local cooling, pretreatment with metabolism-reducing drugs is favorable for cardiac performance after arrest. Steroid premedication should be considered when normothermic arrest with electrically induced ventricular fibrillation is planned.

Myocardial preservation during anoxic arrest. Chemical cardioplegia

Two types of cardioplegic solution--the potassium arrest and the Bretschneider solution, both at 4 degrees C--were compared with regard to protective effect against ischemic damage during 60 min of anoxic cardiac arrest in the dog heart. Both solutions provided equally good protection, which was superior to that given by hypothermia alone.

Role of the Frank-Starling mechanism during maximal semisupine exercise after oral atenolol

Reproducible left ventricular dimensions were found by M-mode echocardiography in eight healthy men in the semisupine position during two maximal bicycle exercise tests, performed with four hours interval. Left ventricular end-diastolic dimension did not increase during maximal exercise, while fractional shortening increased by a decrease in end-systolic dimension. Twelve men studied by the same procedure were given 100 mg atenolol orally just after the first test which conspicuously reduced their heart rate response to exercise. End-diastolic dimension increased significantly from rest to peak exercise after the administration of atenolol in contrast to that before beta blockade, and fractional shortening at maximal exercise increased compared with the preceding control test. We conclude that atenolol changes the left ventricular response to maximal semisupine exercise in normal man, with dilatation and a concomitant increase in systolic myocardial shortening. This suggests that atenolol during maximal exercise reveals the part played by the Frank-Starling mechanism in cardiac reserve. In addition to that mechanism, the increased ventricular emptying is probably also the result of reduced afterload after administration of atenolol.

Ligament function and joint stability elucidated by a new technique

For analysing the ligaments of the ankle joint, their function, and the traumatic mechanisms which cause them to rupture, an apparatus was developed which enables graphic registration of rotatory movements in the ankle joint in two planes simultaneously, when a given torque is applied to the talus. In a modified form, this apparatus is applicable also for other joints. A lever with strain gauges and potentiometers is fixed in the talus of an osteoligamentous preparation. The lever is moved manually, and signals from the strain gauges and potentiometers are collected by a microcomputer for later transfer to a computer service centre where the mobility at the chosen torque is calculated and plotted as mobility patterns. The appearance of these patterns depends upon which ligaments are intact. The patterns plotted in any situation are reproducible, provided that the state of the ligaments is unchanged. In cutting experiments it was possible to demonstrate that rupture of the anterior talofibular ligament may occur simultaneously with partial rupture of the posterior talofibular ligament, although the calcaneofibular ligament remains intact. This occurs if the distortion trauma causing the rupture consists of an internal rotation of the talus, not if it consists mainly of a tilting of the talus in the ankle mortise.

Myocardial preservation during anoxic arrest. Experimental model ventricular fibrillation

An experimental model with anaesthetized healthy mongrel dogs on extracorporeal circulation is described. Anaesthesia and cardiopulmonary bypass are the same as used in clinical practice. Various methods of myocardial preservation were investigated and their protective effect was judged by cardiac performance after termination of 60 min of anoxic arrest. In this study, the first part of an experimental series, electrically-induced fibrillation during 60 min of normothermic and local hypothermic anoxic arrest was investigated. In group I, the hearts were fibrillated immediately after cross-clamping. In group II, which served as controls, the hearts were allowed to fibrillate spontaneously after aortic cross-clamping. All the hearts in group I went into an ischaemic contracture, whereas those in group II showed a 50% recovery, but with a strongly reduced cardiac performance after termination of anoxic arrest and cardiopulmonary bypass. Measurements of myocardial surface pH demonstrated a rapidly developed acidosis during the period of anoxic arrest. The most impressive finding by light microscopy was pronounced myocardial oedema. External cooling by 4 degrees C glucose 5.5% continuously flushed into the pericardial sac in combination with electrically-induced fibrillation proved to be ineffective as a protective method. None of the eight dogs in this group survived. External cooling combined with intraventricular injection of 4 degrees C glucose 5.5% seemed to protect the hearts against ischaemic damage, insofar that all six hearts in this group were able to take over the circulation after declamping. The working capacity was, however, impaired and a relatively long period of mechanical support and stimulation with inotropic drugs was necessary.

Fine structure and FSH binding of Sertoli cells in the blue fox (Alopex lagopus) in different stages of reproductive activity

A clearly different Sertoli cell morphology was found in the immature blue fox and in the adults in and out of season. Immature cells had small, basally, located nuclei rich in peripheral heterochromatin, and few cytoplasmic organelles. Sertoli cells from adults in season had basally located, large, convoluted nuclei with homogenous nucleoplasma and prominent nucleoli. The basal and intermediate parts of the cytoplasm contained an extensively developed ER, numerous mitochondria, free ribosomes, lipid droplets and residual bodies, while the apical cytoplasm showed few distinct structures. In Sertoli cells from adults out of season the nuclei were dislocated towards the lumen, and apart from numerous dilated cisternae of ER, there were generally fewer organelles, but more glycogen particles. A marked rise in FSH binding was found towards the breeding season.

Hydrogenase genes

For a variety of reasons, including the potential industrial applications of hydrogenase, we are interested in the isolation and analysis of hydrogenase genes. In a program focusing on the hydrogen bacterium A. eutrophus H1 and E. coli, we have developed a preliminary concept of the interaction of hydrogenase in cellular metabolism, constructed mutants deficient in hydrogenase activity, and begun the isolation of hydrogenase genes utilizing the technology allowing the in vitro manipulation of DNA. We hope to pursue this project to its ultimate goal: the analysis of the molecular mechanisms involved in the control of expression of these genes and the development of the ability to manipulate the production of hydrogenase.

Silver nitrate pleurodesis in spontaneous pneumothorax

Pleurodesis provoked by instillation of silver nitrate as prevention against recurrence in primary spontaneous pneumothorax has been used for many years in the Department of Thoracic Surgery, Gentofte Hospital, University of Copenhagen. The treatment was originally instituted on a theoretical empiric basis. In a prospective, controlled investigation of pleurodesis versus simple drainage the empiric observations have been confirmed. With simple drainage we found ipsilateral recurrence of pneumothorax in 45%, while no recurrences in the pleurodesis group were found during an observation period of 5-19 months. The difference was statistically significant. The therapeutical gain using pleurodesis was 45% +/- 30%. Silver nitrate pleurodesis results in a longer hospitalization, raises the number of pleurocentesis because of increased pleural effusion and results in more pain than simple drainage. It is, however, our experience that the considerable therapeutical gain more than compensates for these negative effects. We recommend pleurodesis as the treatment of choice in primary spontaneous pneumothorax in patients with only tiny blebs on the surface of the lungs.

Familial occurrence of papillary thyroid carcinoma

We report two kindreds from northern Norway with 7 and 4 cases of papillary thyroid carcinoma in otherwise healthy, nonirradiated subjects. While histologic features were comparable the patient's age at the time of diagnosis was lower and lymph node metastases were more frequent in familial than in nonfamilial cases of papillary thyroid carcinoma from the same region. We conclude that genetic factors can predispose the patient for development of papillary thyroid carcinoma. The high local incidence may be due to interaction between susceptibility gene(s) and environmental factors.

Immediate hemodynamic effect of pharmacological doses of methylprednisolone in dogs, and the influence of speed of injection

Reports of sudden death of patients during i.v. administration of methylprednisolone (M.P.) prompted the present study of the hemodynamic effect of M.P. given i.v. to dogs. Fifteen healthy, mongrel dogs were anesthetized with thiomebumal, fentanyl, droperidol, pancuronium and N2O/O2. With ventilation and circulation in steady state, M.P. 30 mg/kg b.w. was given i.v. either as a push bolus (n=7) or over a 5-min period (n=8). In the bolus group, mean aortic pressure (MAP) and systemic vascular resistance (SVR) had decreased to 72 and 60%, respectively, 1 min after the start of the steroid injection, while heart rate (HR), cardiac index (CI), mean pulmonary arterial pressure (MPAP) and left ventricular work (LVW) had not changed significantly. In the 5-min group, the HR increased by 23%, while the other parameters were unchanged during the injection period. Within 5 min after the termination of the steroid injection all hemodynamic parameters had returned to pre-injection levels in both groups. Sodium, potassium, magnesium, protein and calcium in serum were unchanged in both groups during the injection period and in the following 15 min. A significant, transient fall in ionized calcium was observed in all six dogs in which this ion was measured. It was concluded that rapid i.v. injection of pharmacological doses of M.P. in hemodynamically stable, anesthetized dogs causes immediate, transient decreases in SVR and MAP. The mechanisms may be an alpha adrenergic blocking action or a direct effect on the muscles in the peripheral vessels, combined with a negative inotropic effect on the myocardium, possibly mediated through an impeded calcium release.