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Biomedical subjects

M Maree

Publications and source records attributed to M Maree.

At least 19 recordsLinked to original sources
PubMed1991

Quantitative evaluation of the penile vascular status by means of the 99mTc-penogram in conjunction with either papaverine or prostaglandin E1 in the anaesthetised baboon model.

The evaluation of both the arterial blood supply and the venous drainage of the penis is essential in the assessment of the impotent male. The vasoactive drugs papaverine and prostaglandin E1, as intracavernous injections, cause penile erections by influencing arterial blood supply and venous drainage. These drugs were used in a baboon model together with a 99mTc-penogram to provide information on the vascular status of the penis. An increase in penile blood pool was observed, more dramatic and rapid after administration of papaverine. A quantitative assessment of the vascular status seems possible and will next be monitored in a vascular-compromised baboon for purposes of clinical application.

Alprostadil↗
PubMed1991

A baboon model for in vivo assessment of mucociliary lung clearance.

A suitable baboon model (Papio ursinus) for assessing inhibitory effects on mucociliary lung clearance was required. Clearance of various dimensions of nebulized particles (99mTc-labelled) was monitored with the animals (n = 6) under either ketamine or pentobarbitone anaesthesia. The best prospect of substantial and reproducible clearance in spite of the inhibition by the anaesthesia were obtained with pentobarbitone, and using nebulized radiolabelled particles of diameter range between 10 and 45 microns, thus avoiding trapping in the non-ciliary alveoli.

Aerosols↗
PubMed1990

Investigation by scintigraphic methods of neutrophil kinetics under normal and septic shock conditions in the experimental baboon model.

The purpose of this study was the correlation of neutrophil kinetics with the pathogenic course of septic shock in the baboon model. Radioactively labelled neutrophils were traced in vivo in normal baboons (n = 6) and in Escherichia coli-infected baboons, which were reinjected with labelled autologous neutrophils either 2 h after the onset of the E. coli infusion (procedure A) (n = 3) or simultaneously with the infusion (procedure B) (n = 3). Cell isolation was done according to a method developed in this laboratory. The cells were labelled with tropolonate In 111, resuspended in 1-2 ml plasma and reinjected. One-minute images were taken every 5th min and then hourly for 4 h with a gamma camera and analysed with a data processor. Time-activity curves were obtained for neutrophil washout from the lungs and neutrophil accumulation in the liver and spleen. These curves were compared for normal baboons and for those treated according to procedures A and B. A significant retention of neutrophils in the lungs of baboons with E. coli-induced septic shock was noted as well as an abnormally slow rate of accumulation in the liver and spleen. It also seems that any lung injury which could be attributed to changes in neutrophil behaviour should be traced back to events during the early exposure of neutrophils to bacterial infection.

Animals↗
PubMed1990

Investigation by scintigraphic methods of platelet kinetics under normal and septic shock conditions in the experimental baboon model.

This study concerned the correlation of platelet kinetics with the pathogenic course of septic shock and adult respiratory distress syndrome (ARDS) in the anesthetised baboon model. 111In-tropolonate platelets were traced in vivo in normal baboons (n = 7) and in Escherichia coli-infected baboons, which were reinjected with the labeled autologous platelets either 2 hr after the onset of the E. coli infusion (procedure A: n = 4) or simultaneously with the infusion (procedure B; n = 3). One minute images were taken hourly for 5 hr, using a gamma camera and data processor. Time-activity curves were obtained for platelet clearance from the blood and the lungs and for platelet accumulation in the liver and spleen. A significant retention of platelets in the lungs of baboons with E. coli-induced septic shock was noted, as well as an accelerated clearance from the circulation. Platelets were distributed mainly to the spleen after induction of bacteremia, later substantially moved to the liver, and even later moved back to the spleen.

Animals↗
PubMed1990

Preparation and biokinetic evaluation of various halogenated iminodiacetic acid-type compounds labeled with technetium-99m for hepatobiliary scintigraphy in the baboon (Papio ursinus) model.

In an evaluation of various 99mTc-labeled halogenated (F, Cl, Br, I) iminodiacetic acid (IDA) derivatives for hepatobiliary scintigraphy, it was found that, in the baboon model, none of these compounds performed as well as did disida. F-IDA was least effective, with the lowest biliary excretion and highest renal participation, but multihalogen substitution as in penta-F-IDA increased the biliary specificity and reduced urinary excretion to the extent that penta-F-IDA scored second to disida and even above I-IDA, with its high molecular weight. Surprising also was the relatively good performance of Cl-IDA compared to Br-IDA and I-IDA.

Animals↗
PubMed1989

Using the "integral spleen" method of radiorenogram analysis and a baboon model to compare the diagnostic usefulness of technetium-99m-diethylenetriamine pentaacetic acid to that of various technetium-99m-mercaptoacetyltriglycene formulations and iodine-123-hippuran.

In light of the high price of commercially available mercaptoacetyltriglycene (MAG3) it was decided to attempt a local MAG3-formation and to test this against diethylenetriamine pentaacetic acid (DTPA), 123I-Hippuran, and commercial MAG3 for diagnostic radiorenographic capabilities also in conjunction with furosemide and captopril. A baboon model (n = 6) was used, and the parameters evaluated were obtained by the "integral spleen" method of radiorenogram analysis. Although the images and parameters pointed to 123I-Hippuran and commercial MAG3 as the ideal renal scanning agents and to DTPA as the least so, with the local product an acceptable alternative, the differences were not significant enough to warrant either the purchase of the commercial product or the extensive development of the local product. Inexpensive 99mTc-DTPA in conjunction with modern computer techniques will probably supply most of the answers.

Animals↗
PubMed1989

Left ventricular volume and function changes during beta-blockade and accompanying atrial pacing.

Radionuclide ventriculography was performed at rest and during transoesophageal pacing on nine anaesthetized baboons (Papio ursinus), alternatively with and without administration of a beta-blocker. Left ventricular volumes, cardiac output, and ejection fraction were determined at each heart rate. A gradual decrease in end-diastolic, end-systolic, and stroke volume followed with increasing heart rate, significantly more pronounced under beta-blockade. Cardiac output and ejection fraction showed no significant changes, although tendencies to increase were observed without beta-blockade. Comparisons of these parameter changes were drawn to those previously observed during the first 5 h of septic shock (E. coli). We conclude that the tachycardia present during this phase of shock is not the only contributory factor to cardiac function changes but that other depressant influences prevail as the added effect of the beta-blocker seems to suggest.

Adrenergic beta-Antagonists↗
PubMed1989

Changes in phase analysis patterns of radionuclide ventriculograms obtained from baboons during atrial pacing, septic shock, and induced myocardial infarction.

Changes in intraventricular phase delays, phase angle histograms, amplitude images, and electrocardiograms (ECG) were investigated during oesophageal pacing with and without beta-blockade, after induced myocardial infarction, and during septic shock in the anaesthetized baboon model. Unavoidable triggering from the pacemaker spike and to a lesser extent increased heart rate were responsible for parameter changes during pacing. Myocardial infarction changed contraction patterns, which did not always correlate with conduction changes from the ECG's. Cardiac volume changes during septic shock could be responsible for the abnormal trends in phase angle spread and electrocardiographic data.

Animals↗
PubMed1988

Fourier phase parameters with possible diagnostic importance as obtained from the radionuclide ventriculograms of normal baboons with and without cardiac catheterization and under prolonged anaesthesia.

The possible diagnostic importance of parameters defined from radionuclide ventriculograms and Fourier phase analysis was investigated for data from normal baboons (Papio ursinus) under prolonged anaesthesia (7 hours). Of the 14 animals, 7 were studied using indwelling cardiac catheters. Phase angle differences between the electromechanical activation of the septum and left lateral wall (LLW), and again between the activation of the septum and the apex indicated no significant differences (p greater than 0.05) for the consecutive hourly values for both catheterized and non-catheterized baboons. Consequently, average values and their ranges (mean +/- 1 S.D.) were obtained for these parameters in each group, and they did not differ significantly between the two groups. As could be expected, the activation delays between the septum and LLW, and the septum and apex differed with the latter being significantly longer. The phase angle histogram parameters of atrial peak width, left ventricular plus right ventricular peak width, (LV + RV), LV-to-RV peak separation and LV-to-atrial peak separation were similarly analysed and found not to change significantly between hourly measurements or because of catheterization. Therefore mean normal values and ranges were also obtained for these parameters, possibly to serve as baselines in the diagnosis of subtle conduction pathology.

Anesthesia, General↗
PubMed1988

A progressive radiorenographic (99mTc-DTPA) presentation of surgically induced renal vein hypertension in baboons.

A 99mTc-DTPA radiorenographic study, supported by excretory urography, blood chemistry and eventually histology was performed on 8 chacma baboons (Papio ursinus) after surgical induction of unilateral renal vein hypertension. Frequent sequential repeat renograms during 6 post-operative months detected fluctuating renal behaviour but did not reveal typical course of the disease. Neither did any one of the radiorenographic parameters (TP, T1/2, FF, relative clearances and perfusion) prove to be more sensitive than the others in detecting abnormalities. Initial microscopic or macroscopic haematuria and proteinuria in general eventually cleared up. Light microscopy demonstrated only mild abnormalities. The effects of venous occlusion of the kidney and the prognosis seemed to be variable as was reflected by radiorenography.

Animals↗
PubMed1988

Evaluation of the clinical validity of the "integral spleen" method of renography analysis from parameter changes induced by pharmacological and surgical intervention.

A set of controlled experimental animal procedures involving pharmacological and surgical interventions was carried out to assess the clinical validity of the parameters calculated by the "integral spleen" method of renography analysis. There appeared to be a good correlation between the observed changes of these parameters and current pathophysiological information. In particular, the described method includes an original calculation of the filtration fraction without blood and urine sampling or a second tracer injection. This calculation was experimentally validated here.

Animals↗
PubMed1988

Comparison of blood flow parameters measured by Doppler ultrasound and radionuclide techniques in the baboon (Papio ursinus).

Ascending aortic blood velocity was measured in the baboon (Papio ursinus) by using continuous wave Doppler ultrasound. The blood flow parameters thus obtained were compared to those by the standardized radionuclide technique. It appears that, due to the anatomical position of the ascending aorta and brachiocephalic trunks in relation to the ultrasound beam, Doppler ultrasound does not provide an accurate method of measuring aortic blood velocity in the baboon, which could be the reason for the poor correlation of the results from the two techniques.

Animals↗
PubMed1988

Scintigraphic phase analysis of abnormal A-V conduction in a baboon.

During an interventional cardiac investigation on an anaesthetised baboon (Papio ursinus) the animal developed A-V block. Scintigraphic phase analysis leading to quantified intraventricular delays and histogram characteristics pointed to abnormalities which persisted even after A-V block was replaced by nodal tachycardia as was reflected by the electrocardiogram. This indicated towards an increased diagnostic sensitivity with the use of phase analytical methods.

Animals↗
PubMed1987

The effect of an oral gold preparation on the gastrointestinal tract motility in two species of experimental animals.

The oral gold preparation, auranofin, used in rheumatoid arthritis has been reputed to cause chronic diarrhea. To investigate this the G.I. tract motility was measured before auranofin therapy and after 1, 3, and 5 weeks of therapy using scintigraphy following indium-111-labeled meals in three beagle dogs. The gastric emptying times of the dogs accelerated throughout the duration of the experiment, although the large bowel transit times did not seem to be affected. The affect of auranofin on the stools of the baboon Papio ursinus was also noted. The baboon stools were observed for any change in consistency. Sigmoidoscopic examination including mucosal biopsies was carried out monthly over a 6-month period. The baboon's stools were noted to become very soft in consistency, but histology indicated no mucosal changes.

Administration, Oral↗
PubMed1987

Phase mapping from left ventricular radionuclide ventriculograms: interobserver reliability and accuracy of the programme.

Phase analysis of data from radionuclide ventriculograms is known to provide space-time information on the mechanical emptying of pixels located in the ventricular regions. It could therefore perhaps be useful for detecting abnormal sequences of contraction of the ventricles as well as to localize sites of premature electromechanical action. The phase programme used in this investigation is designed to trace the electromechanical action of the ventricles from colour-coded phase images (first harmonic Fourier transform), not only visually from a cinematic representation, but particularly from a data output of x, y coordinates and phase angles of sites chosen as they empty in the ventricular regions. Six healthy baboons were subjected to conventional radionuclide ventriculography, performed hourly for the duration of 11 h under anaesthesia. The programme was used by two independent observers to map the progression of emptying for each of the thus acquired 66 left ventricular phase images. The interobserver reliability and the accuracy achieved in mapping normal contraction patterns was found to be good. Abnormalities which appeared during the prolonged anaesthesia and which were confirmed with 12 lead electrocardiography were likewise detected consistently.

Animals↗
PubMed1987

Baboon (Papio ursinus) model to study deep vein thrombosis using 111-indium-labeled autologous platelets.

This study evaluates the chacma baboon as a model for investigations on deep vein thrombosis (DVT). There is a good correlation of the baboon and human thrombelastographic parameters (r-time, k-time, ma). Investigation on the diagnostic efficacy of 111 In-labeled platelets as an imaging agent for DVT cast considerable doubt on the procedure, owing to the age of the thrombus.

Animals↗