A new approach to the classification of muscle health: preliminary investigations.

Objective: Upper leg skeletal or lean tissue mass (LTM), strength and muscle quality have emerged as time-sensitive indices of muscular health. The aim of this study was to generate a comparative data set based on these indices, in healthy young (n  =  30, 29.0  ±  3.

A preclinical assessment of d.l-govadine as a potential antipsychotic and cognitive enhancer.

Tetrahydroprotoberberines (THPBs) are compounds derived from traditional Chinese medicine and increasing preclinical evidence suggests efficacy in treatment of a wide range of symptoms observed in schizophrenia. A receptor-binding profile of the THPB, d.l-govadine (d.

Chronic catecholamine depletion switches myocardium from carbohydrate to lipid utilisation.

Purpose: Chronic cardiac transplantation denervation (i.e., global sympathetic denervation with myocardial catecholamine depletion, plus parasympathetic denervation) is known to inhibit myocardial oxidation of glucose.

Thrombosis in one coronary artery causes generalized coronary vasoconstriction in a dog model of unstable angina.

We investigated the effect of thrombosis in one coronary artery upon the vascular resistance of another coronary artery. In previous investigations, using an animal model of unstable angina, we have observed increased resistance downstream from thrombus within a left circumflex coronary artery (LCx) stenosis and vasoconstriction of collateral vessels from the left anterior descending artery (LAD) supplying the distal LCx vascular bed. In the present paper, we induced thrombosis within a stenosis of the LCx of 16 beagle dogs, and observed the changes in blood flow to the myocardium supplied by the LAD using the radioactive microsphere technique.

Measurement of coronary collateral flow and resistance in the presence of an open critical stenosis, and the response to intra-arterial thrombosis.

Objective: (1) Can one measure coronary collateral flow around an open critical stenosis? (2) Does intracoronary platelet thrombosis affect native coronary collateral vessels?

Methods: We measured regional myocardial blood flow by the radioactive microsphere technique in seven anaesthetised dogs with an ultrasonic flowmeter on the circumflex branch of the left coronary artery (LCx). Measurements were made (a) in a control period, (b) after induction of a tight stenosis on the LCx, and (c) after additional arterial damage at the stenosis to induce intraluminal thrombosis. Collateral flow was calculated from LCx tissue flow(in ml/min/g tissue) minus LCx flowmeter flow which is in ml/min.

Downstream resistance effects of intracoronary thrombosis in the stenosed canine coronary artery.

Objective: The presence is well established in unstable angina of intracoronary thrombosis in a stenosed epicardial coronary artery. The effects of the thrombus formation on the distal microcirculation are however still unclear.

Methods: We adapted the Folts canine model of left circumflex coronary arterial stenosis and intracoronary thrombosis by the insertion of a pressure catheter distal to the stenosis and by the use of 15 microns radioactive microspheres for measurement of regional myocardial blood flow.

A fast responding intra-arterial pH electrode for use in the peripheral artery of adult humans and large mammals: a technical development for use in research.

A rapidly responding intra-arterial pH electrode has been developed to provide a continuous record of arterial pH (pHa) in the radial artery of adult humans and large mammals. The current method for measuring pHa is discontinuous and is achieved by taking blood samples and subsequently measuring pHa in a blood gas analyser. The development of an intravascular electrode is needed for studies on the chemical control of pulmonary ventilation when a continuous record of pHa is required.

Beneficial effect of the calcium-sensitizing drug EMD 57033 in a canine model of dilated heart failure.

1. Pacing-induced heart failure was studied in eight dogs. Heart failure was induced by right ventricular pacing at 250-260 beats/min for 6 weeks.

Tachycardia-induced failure alters contractile properties of canine ventricular myocytes.

Objective: Rapid cardiac pacing has been used as a model for experimentally-induced cardiomyopathy. However, its relevance to human heart failure is not clear at present because little is known about changes in size and function of ventricular myocytes. We have therefore studied the responses to graded increases in frequency and calcium in canine ventricular myocytes from failing hearts.

Failure of thrombin inhibition to prevent intracoronary thrombosis in the dog.

1. Recurrent occlusion after thrombolysis may be caused by thrombin receptor-mediated platelet thrombosis occurring in a residual stenosis. To test the relative importance of the platelet thrombin receptor under conditions of high shear and endothelial damage (the Folts model of intracoronary thrombosis) we used the specific thrombin inhibitor recombinant hirudin.

Exercise electrocardiography and aortic Doppler velocimetry in asymptomatic identical twins discordant for type 1 (insulin dependent) diabetes.

Objective: To determine the influence of insulin dependent diabetes on the prevalence of myocardial ischaemia and on global left ventricular systolic performance.

Design: Stress treadmill electrocardiograms and simultaneous Doppler measurement of aortic maximum acceleration were obtained during exercise on symptom free subjects. The electrocardiograms were scored blindly according to the Minnesota code.

Enoximone in chronic stable angina: a double-blind placebo-controlled cross-over trial.

Enoximone, a phosphodiesterase inhibitor (PDEI), has both positive inotropic and vasodilatory properties. We examined the effect of a single oral dose of enoximone as compared with placebo on myocardial ischaemia and global left ventricular (LV) function using both exercise ECG and Doppler measurements of aortic blood flow, respectively. Twenty patients (16 men, 4 women) with a mean age of 59 years and stable angina were studied.

Infarct size in rabbits: a modified method illustrated by the effects of propranolol and trimetazidine.

Following a 45-min period of coronary occlusion the myocardial infarct that developed after 24 h of blood reperfusion in the rabbit heart was studied in three groups of animals: controls (n = 7), and those pretreated with 3 mg.kg-1 of the piperazine derivative, trimetazidine (n = 7) or propranolol at 0.3 mg.

Effects of trimetazidine on in vivo coronary arterial platelet thrombosis.

We used Folts' model of critical coronary artery stenosis with endothelial damage, which measures platelet-rich thrombus accumulation from cyclic flow reductions (CFRs). This paper reports results applied to trimetazidine, a member of the piperazine group. Trimetazidine at a dose of 1 mg/kg completely abolished CFRs caused by accumulating thrombus in the circumflex coronary artery in 4 of 8 open-chest anesthetized beagles.

Dispersion of coronary artery thrombi by antagonism of platelet serotonin receptor in the dog.

Objective: Blockade of platelet 5HT2 receptors prevents coronary artery thrombi. This study explores the dispersal of established thrombus by such 5HT2 antagonism.

Methods: Seven open chest anaesthetised beagles were used in a repeated measures study of the action of MDL 11,939 to remove the participation of platelet 5HT2 receptors in the natural history of intracoronary thrombosis with cyclic blood flow reduction.

Advantages of a narrow-range, medium molecular weight hydroxyethyl starch for volume maintenance in a porcine model of fecal peritonitis.

Objective: To compare the effectiveness of two hydroxyethyl starch solutions of different molecular weight ranges for volume maintenance in a porcine model of fecal peritonitis.

Design: Randomized prospective trial.

Setting: Laboratory investigation.

Right ventricular dynamic cardiomyoplasty: an experimental model.

The effectiveness of dynamic cardiomyoplasty as a means of haemodynamic support in heart failure remains controversial. We have undertaken a study of right ventricular dynamic cardiomyoplasty in sheep using intravenous propranolol to provoke heart failure. Muscle conditioning was performed with cardiomyostimulators following a previously established protocol.

Improved heart and lung preservation in a rat model.

We investigated the efficacy of four different preservation solutions in a heart-lung model in the rat. The heart and lungs of the donor were perfused under standardised conditions of temperature, pressure and flow. We studied 4 groups: group 1 received Stanford solution to heart and lung; group 2 received St.

Myocardial protective effects of lidoflazine during ischemia and reperfusion.

The myocardial protective effect of intravenous (i.v.) lidoflazine with potassium cardioplegia and hypothermia (28 degrees C) was investigated in 21 greyhounds.

Pretreatment with pentoxifylline improves the hemodynamic and histologic changes and decreases neutrophil adhesiveness in a pig fecal peritonitis model.

We investigated pentoxifylline (PTF) as a pretreatment of septic syndrome in pigs with fecal peritonitis. In the untreated group there was a progressive decrease in mean arterial pressure (MAP), cardiac output, mean pulmonary artery wedge pressure (WP), and a progressive rise in mean pulmonary artery pressure (MPAP), pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), heart rate (HR), and core temperature (T). In those pigs given PTF there was a significantly smaller increase in SVR throughout and in PVR after 270 min.

Effects on infarct size of reperfusion and pretreatment with beta-blockade and calcium antagonists.

The "mass of tissue at risk" and the myocardial infarct developed was studied in dogs subjected to either 24-h occlusion of the left anterior descending coronary artery or 2-h occlusion followed by 22-h reperfusion. The "mass of tissue at risk" was defined under anaesthesia at the time of occlusion using the microsphere technique. Twenty-four hours later the hearts were removed, sliced transversely and stained with 2,3,5-triphenyltetrazolium chloride to define the infarcted tissue.

Pentoxifylline reduces pulmonary leucostasis and improves capillary patency in a rabbit peritonitis model.

This study examines the changes in pulmonary leucostasis and capillary ultrastructure in 18 rabbits divided into three groups. Those in the first group were sham operated, and those in the second and third groups underwent peritonitis induction; those in the latter group were treated with pentoxifylline (PTF). White blood cells (WBC) were counted, and tissue area, total capillary area, and capillary patency were measured from electron micrographs of lung tissue.

An in vitro slice preparation of the cat lateral geniculate nucleus.

A slice preparation of the cat thalamus containing the lateral geniculate nucleus and the terminal portion of the optic tract is described. Ultrastructurally the slices remain relatively normal for only a short time after cutting. Indeed most cellular elements deteriorate quickly with time but patches of relatively intact tissue were still present even 10 h after cutting and maintenance in a storage bath.

Effect of defibrinogenation on the early patency rate of experimental small calibre arterial grafts.

The effect of defibrinogenation with Arvin was studied in a new animal model of early thrombosis of a 3 mm diameter polytetrafluoroethylene (PTFE) graft with a poor run-off. Fifteen control animals were compared with fourteen animals treated with subcutaneous Arvin 20 units kg-1 body weight day-1, starting 2 days before surgery and continuing for 2 days postoperatively. The peroperative fibrinogen level in the controls was 2.

A phospholipase inhibitor modifies the pulmonary damage associated with peritonitis in rabbits.

Peritonitis has been produced in rabbits by the spreading of 5 ml of caecal contents throughout the peritoneal cavity. After sacrifice at 5 h, electron microscopy revealed a increase of 600% in PMN and 1200% in lymphocytes in the pulmonary capillaries of the test animals when compared to the sham operated group. The pulmonary capillaries in the test group showed a 27% reduction in their luminal area, which was associated with a 73% reduction in their patency due to occlusion by WBC and cell debris.