Biomedical subjects

I Dormehl

Publications and source records attributed to I Dormehl.

14 recordsLinked to original sources

PubMed2000

Evaluation in the baboon model of (99m)Tc-biguanide as a tracer for renal imaging.

Studies in various animal species have recently shown that (99m)Tc-BIG has practical and dosimetric benefits for renal imaging that could probably make it a good alternative to (99m)Tc-2, 3-dimercaptosuccinic acid ((99m)Tc-DMSA). In this study, using the baboon experimental model, the biodistribution of (99m)Tc-BIG and (99m)Tc-DMSA are compared. It is demonstrated that early good contrast imaging and more favourable dosimetry is possible with (99m)Tc-BIG compared to (99m)Tc-DMSA, confirming the quoted previous findings with small animals. Time-activity curves for kidneys and other organs support these findings, and MIRDOSE software provided the dosimetry.

Animals↗

PubMed1998

Targeted radiotherapy with Sm-153-EDTMP in nine cases of canine primary bone tumours.

Nine dogs with primary bone tumours were treated with Samarium-153-EDTMP (Sm-153-EDTMP). Conventional treatment protocols were precluded by the size of the dogs and the owners' refusal of limb amputation. All the tumours were of the appendicular skeleton; 4 were confirmed osteosarcomas. The other 5 tumours were radiologically suspect for osteosarcoma. Bone scans were performed on all dogs using Technetium-99m-methylene diphosphonate (Tc-99m-MDP) before administration of Sm-153-EDTMP. Regions of interest were identified over the contralateral limb at the same site as the tumour and counts per pixel were recorded for the tumour and contralateral limb and expressed as a ratio. The dogs were given 1 injection of 37 MBq/kg (1 mCi/kg) of Sm-153-EDTMP intravenously. Thoracic and primary tumour site radiographs were taken at monthly or 2-monthly intervals to monitor progression of the primary tumour and search for evidence of metastasis. Two dogs showed no response to treatment, with an increase in bone pain, and were euthanased within 1 month. In 1 dog, a tumour of the scapula underwent complete involution and the dog is considered free of disease at 20 months post Sm-153-EDTMP treatment. The overall tumourcidal effect of a single dose of Sm-153-EDTMP on primary bone tumours was difficult to evaluate in this group of dogs, as, with one exception, all the primary tumours progressed over time and the dogs were euthanased. Pain control, for which Sm-155-EDTMP is used in man, was not evident, except in the dog that responded completely to treatment.

Age Factors↗

PubMed1993

Comparative myocardial imaging in the baboon with 123I-labelled ortho and para isomers of 15-(iodophenyl)pentadecanoic acid (IPPA).

The use of various animal models for researching radioiodinated fatty acid cardiac metabolism has been proven to be risky. This fact is here confirmed in the higher primate. Six baboons were injected on different occasions with 123I-labelled para and ortho isomers of 15-(iodophenyl) pentadecanoic acid (123I-pPPA and 123I-oPPA, respectively) for dynamic scintigraphy, followed by a Na123I injection at 30 min for blood background correction. Times for maximum myocardial tracer uptake (Tmax), and half-times of clearance (two phases T1/2(1) and T1/2(2)) from biexponential fitting of the time-activity curves proved statistically not different for pPPA and oPPA (P > 0.05). A repeat study at a later stage on the same baboons included pretreatment (2 h pretracer) with a carnitine palmitoyl transferase I inhibitor (Extomoxir; 10 mg kg-1) to block myocardial beta-oxidation. Time-activity curves with Tmax, T1/2(1) and T1/2(2) followed as above and were compared to the initial uninhibited values. Blocking of the carnitine shuttle was demonstrated by significantly increased retention of 123I-pPPA and 123I-oPPA. Thus both the tracers are beta-oxidized in the baboon myocardium, which is different in rat and human studies. In rats both isomers wash out from the myocardium, but 123I-oPPA is not metabolized. In humans the 123I-pPPA is beta-oxidized as with rats, but the 123I-oPPA is retained in the lipid pool of the myocardium. Simultaneous multiple consecutive gated blood pool studies (six of 1 min each) provided encouraging perfusion-related, background corrected images, and corresponding uptake information.

Animals↗

PubMed1993

Non-invasive three-dimensional localisation of arrhythmogenic foci in Wolff-Parkinson-White syndrome and in ventricular tachycardia by radionuclide ventriculography: phase analysis of double-angulated integrated single photon emission computed tomography (SPECT).

A new tomographic technique combined with phase analysis was used to detect premature and ectopic ventricular contraction patterns in 15 patients with Wolff-Parkinson-White syndrome and during ventricular tachycardia in seven patients. Data generated by gated single-photon emission computed tomography (SPECT) were analysed by backprojection of the Fourier coefficients, double-angulation, and integration to thick slices containing the ventricles, thus allowing visualisation of the contraction patterns in three perpendicular views. The results were compared with those of catheter mapping. In nine patients with Wolff-Parkinson-White syndrome the site of initial contraction detected was identical with the site of the accessory pathway found by catheter mapping. The sites of origin of the ventricular tachycardias determined by catheter mapping were within 3 cm of the sites detected by the new technique. This new technique seems to be a promising non-invasive method for localising ectopic ventricular activity that will considerably shorten the time required for subsequent invasive procedures.

Adult↗

PubMed1992

The baboon model under anesthesia for in vivo cerebral blood flow studies using single photon emission computed tomographic (SPECT) techniques.

Single photon emission computed tomography of the brain can be useful in animal experimentation directed toward cerebral conditions. A well established and understood baboon model, necessarily under anesthesia, could be especially valuable in such investigations. Six normal baboons were studied under various anesthetic agents and their combinations: ketamine, thiopentone, pentobarbitone, and halothane. Cerebral blood flow (CBF) studies were performed with 99mTc-HMPAO. CBF effects from various anesthesia were detected, requiring careful choice of the anesthesia for cerebral investigations.

Anesthesia↗

PubMed1991

Effect of Pseudomonas aeruginosa-derived pyocyanin and 1-hydroxyphenazine on pulmonary mucociliary clearance monitored scintigraphically in the baboon model.

The effect of products of the bacterium Pseudomonas aeruginosa on mucociliary lung clearance has been monitored in vivo in the baboon model by scintigraphy. Clearance was found to be inhibited by both 1-hydroxyphenazine and pyocyanin, and a dose-effect was illustrated by the former. This confirms previous in vitro results as well as results from work on guinea-pigs, and holds good prospects for the use of the baboon model under anesthesia in such investigations.

Aerosols↗

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↗

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↗

PubMed1983

Beta-adrenergic blocking drugs and renal function.

A baboon model was used to investigate the effects of atenolol, nadolol, sotalol and labetalol on renal function. The glomerular filtration rate (GFR) and renal blood flow (RBF) were measured, using radionuclides and a gamma camera, before and after 1 week's oral administration of these drugs. All the drugs caused an increase in the GFR, but this reached statistical significance only in the cases of sotalol (P less than 0,025) and labetalol (0,05 less than P less than 0,10). The RBF was not significantly changed, although it decreased in all cases.

Adrenergic beta-Antagonists↗

PubMed1982

The feasibility of a renogram study in dogs with radiopharmaceutical 99mTc-DTPA.

The present study is one of in vivo 99mTc-DTPA renography, successively involving conscious healthy dogs under acepromazine maleate sedation and dogs under the narcotic sodium thiopental. It was found that during the running of the renogram the animal had to be kept completely immobile and that constant infusion narcosis with sodium thiopental produced this immobility without affecting the renograms unduly. However administration of a thiopental bolus did have an adverse effect on the renogram. Sedation with acepromazine maleate significantly increased the time to peak and the excretion phase as presented by the slope. These effects are thought to be due to a decreased blood pressure with concomitant renal bloodpooling and retarded bloodflow. The radioisotope renogram appears to hold great promise for both clinical and research applications. The equipment required for this application however, is so costly that it would only be financially feasible for major centres.

Acepromazine↗

PubMed1981

[The diagnosis of ischemic heart diseases with thallium-201].

Thallium-201 is very suitable for cardiac imaging because of its physical characteristics and biological behaviour. Perfusion defects caused by ischaemia, necrosis or fibrosis are represented by 'cold spots' on the myocardial scan. In this article we report our experience with this method in the diagnosis of ischaemic heart disease in 117 patients. Excellent correlation was found with clinical, electrocardiographic and angiographic parameters. Both sensitivity and specificity for the diagnosis of ischaemic heart disease were higher with 201Tl scintigraphy than with existing diagnostic methods.

Adult↗

PubMed1981

[Imaging of the myocardium with thallium-201].

Myocardial imaging after the intravenous injection of radionuclides offers a non-invasive, highly sensitive and reliable method for the detection of myocardial infarction and regional myocardial ischaemia. Considerable attention has been given to various isotopes as a means of independent assessment of regional blood flow distribution in the normal, ischaemic or infarcted myocardium. The clinical use of cationic tracers such as potassium-43 and rubidium-81 is based upon the principle that tracer uptake is proportional to regional myocardial blood flow. A region of absent tracer uptake suggests the presence of previous infarction or fibrosis, while a new perfusion defect appearing after stress suggests transient ischaemia. These isotopes, however, have significant physical limitations as imaging agents. The physical and biological properties of thallium-201, however, make it ideally suited for imaging of the myocardium with currently available imaging equipment.

Coronary Circulation↗

PubMed1980

In vivo nuclear techniques in veterinary medicine.

A description is given of the more relevant procedures of diagnostic nuclear medicine as well as of future trends in this field, especially with regard to in vivo research and clinical applications at the biochemical level. The part played by animal models in the past and present is emphasised. The inclusion of a nuclear medicine facility, as equipped and run by the Atomic Energy Board at the H.A. Grové Animal Research Centre is put into perspective.

Animals↗

PubMed1978

Cerebral revascularization by extracranial-to-intracranial anastomosis.

Four cases are presented in which a superficial temporal artery was anastomosed to the cortical branch of the middle cerebral artery. The surgical technique is described. The indications and contraindications and results of the procedure are briefly discussed by referring to recent publications on the subject.

Adult↗