Coronary thrombolysis with recombinant human tissue-type plasminogen activator: a prospective, randomized, placebo-controlled trial

Forty-five patients with acute transmural myocardial infarction and angiographically confirmed complete coronary occlusion were prospectively randomized, two for one, to treatment of acute coronary thrombosis with intravenous recombinant human tissue-type plasminogen activator (rt-PA) or placebo. Each of five additional consecutive patients was treated with a high dose of rt-PA for 2 hr. Twenty-five of 33 patients (75%) receiving 0.5 to 0.75 mg/kg of rt-PA over 30 to 120 min had angiographically proven recanalization within 90 min of initiation of therapy. Only one of 14 patients given placebo had spontaneous recanalization within 45 min (p less than .001). Thirteen placebo-treated patients were crossed over to the intracoronary rt-PA group. Nine (69%) exhibited subsequent recanalization within 45 min. Levels of circulating fibrinogen decreased after treatment with rt-PA by an average of only 8% of baseline values. None of the patients manifested a depletion of fibrinogen level to below 100 mg/dl. Six patients who were completely unresponsive to rt-PA were subsequently treated with intracoronary streptokinase and none responded. Thus, either intravenous or intracoronary rt-PA induced coronary thrombolysis without eliciting clinically significant fibrinogenolysis in patients with evolving myocardial infarction due to thrombotic coronary occlusion.

Oligo-2',5'-adenylate synthetase activity in peripheral blood mononuclear leukocytes in various diseases

Interferon induces oligo-2',5'-adenylate synthetase in cells. In various diseases, interferon was detectable in the circulation or was produced spontaneously from peripheral blood mononuclear leukocytes. The oligo-2',5'-adenylate synthetase activity in peripheral blood mononuclear leukocytes was examined in various diseases, including systemic lupus erythematosus, sarcoidosis, Vogt-Koyanagi-Harada disease, and Behcet's disease. The activity of this enzyme was significantly increased in systemic lupus erythematosus (P less than 0.01), sarcoidosis (P less than 0.01), and Vogt-Koyanagi-Harada disease (P less than 0.01) compared with that in controls, but the increase of activity was not significant in Behcet's disease (P greater than 0.05).

Chronotropic effects of succinylcholine and succinylmonocholine on the sinoatrial node

The mechanism of bradycardia caused by the administration of succinylcholine has not been fully elucidated. Accordingly, the effects of succinylcholine and succinylmonocholine on the sinoatrial node were studied in 35 mongrel dogs. The sinus node artery was selectively perfused with autologous blood from a femoral artery at a constant pressure of 100 mmHg, and 30 to 1,000 micrograms of succinylcholine or succinylmonocholine was administered directly into the artery. Succinylcholine caused a transient (63-600 s) dose-related positive chronotropic effect. The heart rate was increased to 14.4 +/- 2.1% (mean +/- SE) above the control value after the administration of 1,000 micrograms of succinylcholine. This positive chronotropic effect was inhibited by pretreatment with pindolol or reserpine. By contrast, succinylmonocholine produced a transient (30-248 s) dose-related negative chronotropic effect. The heart rate was decreased to 17.5 +/- 1.4% below the control value after administration of 1,000 micrograms of succinylmonocholine. The negative chronotropic effect was blocked partially by atropine. It was concluded that the positive chronotropic effect of succinylcholine may be mediated through beta-adrenergic receptor stimulation by catecholamine released from the adrenergic nerve endings in the sinoatrial node, and that the negative chronotropic effect of succinylmonocholine may be the result of excitation of cholinergic receptors in the sinus node. However, a direct effect of succinylmonocholine on the sinus node could not be ruled out.

Supraclavicular brachial plexus block using a nerve stimulator and an insulated needle

A technique employing a nerve stimulator and an insulated needle was used for supraclavicular brachial plexus block in 71 patients using 0.5% plain bupivacaine 15-20 ml. The mean minimal stimulating current to produce paraesthesia was 0.09 mA. The plexus was identified at a mean depth of 27 mm below the skin. The block was successful in 98% of patients when the stimulation was felt in the index, middle or ring finger, but was often incomplete when felt in the thumb or little finger.

Effect of thiamylal on the sensitivity of glycerinated cardiac fibres to calcium

Clarification of the mechanisms of the myocardial depression produced by thiamylal was sought by studying the effect of thiamylal upon the sensitivity of contractile proteins to calcium (Ca2+), by using glycerinated muscle fibres from the canine right ventricle. The dose--response relationship between the concentration of Ca2+ and the force of contraction of the glycerinated cardiac muscle fibres was not shifted from the control curve by the administration of thiamylal 67 microgram ml-1. This result suggests that the changes in the sensitivity of contractile proteins to Ca2+ are not responsible for the depression of myocardial performance produced by thiamylal.

Tracheal constriction by morphine and by fentanyl in man

The effects of morphine and fentanyl on tracheal smooth muscle tone were studied in 38 patients during induction of anesthesia. Endotracheal tube cuff pressure was used to measure tracheal tone. Anesthesia was maintained with nitrous oxide, 70 per cent in oxygen, and pancuronium and ventilation was controlled with a respirator. Morphine, 0.5 mg/kg, produced a biphasic response, initially causing tracheal dilatation and then tracheal constriction. Ten minutes after morphine injection, cuff pressure increased to significantly (21 +/- 8 per cent) above control. Morphine-induced tracheal constriction could be completely blocked by the prior administration of atropine, 0.5 mg. Fentanyl, 0.006 mg/kg, also produced significant tracheal constriction, cuff pressures increasing to 44 +/- 11 per cent above control at 10 min. Fentanyl-induced tracheal constriction could be blocked by pretreatment with droperidol, 0.25 mg/kg. At equianalgesic doses, morphine and fentanyl produced similar tracheal constriction.

Cardiac performance during prolonged halothane anaesthesia in the cat. Isolated heart muscle study

The contractile response of papillary muscles, isolated from normal cats, to prolonged administration of halothane at minimum alveolar anaesthetic concentration (MAC) was studied. Average values of maximal velocity of shortening (Vmax) and maximal developed force (Fm) obtained in 12 muscles during the 1st, 2nd and 3rd hour of exposure to halothane anaesthesia were significantly less than those obtained during the control period and after recovery from halothane. There were no significant differences in values over a 3-h period. When post-extra-systolic potentiation was induced by paired electric stimulation, average values of Vmax and Fm increased significantly. We conclude that prolonged administration of halothane at a constant concentration resulted in a sustained depression of myocardial contractility without tissue tolerance. The myocardium depressed by halothane, however, still retains the ability to respond to additional inotropic stimulation.

Electrical callus and callus formation by electret

The callus formed by passing an electric current through bone is called electrodynamic callus. The amount of electrical current determines the quality of the callus (osseous, cartilagenous, or fibrous). Callus forms first at the negative pole and grows toward the positive pole. The callus formed by placing a teflon film electret near the surface of bone is called electrostatic callus. The amount of this callus is larger when the bone is wrapped by the electret film than when the film is laid over the bone.

Electret induced callus formation in the rat

Wrapping the mid-femoral shaft of the rat with a Teflon film electret produced a bony callus in 9 out of 10 animals. This model of electret-induced callus formation should lend itself to the histo-biochemical study of electrically induced osteogenesis.

The electrical induction of callus formation and external skeletal fixation using methyl methacrylate for delayed union of open tibial fracture with segmental loss

A case of delayed union of an open tibial fracture with segmental loss is presented in which electricity was applied to the bone defect through two screws that were connected to a methy methacrylate skeletal fixation device. The fracture developed electrically induced callus formation around the cathode, callus extended to the anode, and solid bony union ensued. External skeletal fixation using methyl methacrylate is convenient and is a suitable adjunct to electrical stimulation of fracture healing.

Electron microscopic observations of FL cells infected with herpes simplex virus. III. Dense bodies

FL cells infected with the -GCr Miyama strain of herpes simplex virus at an adsorbed multiplicity of approximately 10 were fixed at late stages of infection and examined by electron microscopy. Dense bodies containing electron-dense material and surrounded by a limiting membrane were occasionally observed in the perinuclear disternae and in intranuclear vacuoles. Budding of electron-dense material to the cisternae with acquisition of a limiting membrane at the inner nuclear membrane was also occasionally observed. These findings are in constrast with observations that in cells infected with cytomegalovirus numerous dense bodies and their budding process were observed only in the cytoplasmic area.

Direct effects of acryl bone cement monomer on isolated heart muscle

Experiments were carried out in isolated dog heart muscle to determine the direct effect of acryl bone cement monomer on the myocardial contractility. The monomer caused a dose-dependent decrease in the maximum velocity of shortening (Vmax) and the maximum force development (Fm), consequently resulting in a leftward shift of the force-velocity relation curves. There was also a concomitant decrease in work, power, the maximum rate of force development (max dF/dt) and time to peak force (TPF) from the onset of force development. These results indicate that acryl bone cement monomer exerts a direct negative inotropic effect on the myocardium and that the myocardial depression due to free monomer absorbed from the mixed bone cement into the systemic circulation during operation seems to be one of the major causes of the cardiovascular complications associated with the clinical application of bone cement.