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R Bontemps

Publications and source records attributed to R Bontemps.

13 recordsLinked to original sources
PubMed1994

Effects of an ectodermal microceptor preparation on motor coordination in cerebellar mutant mice.

Lurcher mutant mice, characterized by degeneration of the olivocerebellar system, and dystonia musculorum (dt) mutant mice, characterized by degeneration of spinocerebellar fibers, were treated with an ectodermal microceptor preparation (EMP), a compound containing natural substances derived from embryonic bovine ectodermal tissue, or with placebo, and evaluated in motor coordination tests. EMP-treated lurchers, but not dt mutants, were quicker to initiate movement than placebo-treated controls in the inclined beam test. No group differences were found in terms of distance travelled on the beam or in motor coordination assessed in a more challenging coat-hanger test. These results indicate that ectodermal microceptors may improve movement initiation of cerebellar-related disorders in animals, but that these effects are test and disease-specific.

Animals↗
PubMed1982

Mixed micelle properties and intestinal cholesterol uptake.

The solubilizing powers of taurocholate, taurochenodeoxycholate and tauroursodeoxycholate for monoolein and cholesterol, and the size of the bile salt-monoolein-cholesterol micelles have been determined. For the three bile salt species, the micellar size depends on the saturation with monoolein. As a result, for a given bile salt to monoolein ratio, the taurochenodeoxycholate micelles are smaller than those of taurocholate and both are smaller than those of tauroursodeoxycholate. Intestinal cholesterol uptake has been studied in vitro as a function of the micellar size and the saturation degree with cholesterol. For a given bile salt to monoolein ration and 1) for low cholesterol concentrations, taurocholate leads to the greatest rates of uptake ; 2) for high cholesterol content, taurochenodeoxycholate induces the largest uptake. The specific micellar characteristics of the tauroursodeoxycholate micelles clearly demonstrate why this bile salt is of so little help in the intestinal uptake of cholesterol.

Animals↗
PubMed1982

Application of conventional (DC) and differential pulse polarography (DPP) to the quality control of benzothiadiazines in tablets. Simultaneous determination of hydrochlorothiazide and dihydralazine sulphate in mixtures with minimization of interaction by the use of a zero covariance in the calibration.

A previous study of the polarographic behaviour of 14 benzothiadiazines having diuretic properties enabled possible reaction mechanisms to be proposed and gave the opportunity to determine the best conditions for analytical application. The results obtained with benzthiazide as an example of the unsaturated compounds, bendrofluazide as the dihydro compound, and hydrochlorothiazide determined together with dihydralazine are reported. The electroactivity of these last two substances was made the object of a mathematical study for the correction of reciprocal interference.

Bendroflumethiazide↗
PubMed1982

Gamma camera quantitation of thallium-210 redistribution at rest in a dog model.

Defects seen at rest on thallium-201 (201TI) scintigraphy can disappear over time. We obtained sequential 5-minute scans over 127 +/- 9.4 minutes in seven open-chest dogs with fixed, stable regional flow reductions (normal zone flow 0.76 +/- 0.09 ml g-1/min, ischemic zone flow 0.49 +/- 0.04 ml g-1 min [mean +/- SEM], p less than 0.05) as determined by microsphere injection. Sequential 5-minute scans were obtained after i.v. injection of 1.5 mCi of 201TI. Data were stored in a 64 x 64 pixel computer matrix. Qualitatively, defects that showed redistribution were seen in all dogs. Quantitatively, greater count loss from peak activity distinguished the normal zone, but overlap was great. Alternate quantitative methods using background subtraction altered the characteristics of the time-activity curves, but did not enhance the separation of ischemic from normal zones. Patterns of 201TI redistribution from gamma camera imaging are profoundly influenced by the method of quantitation. No single method of quantitative analysis separated ischemic from normal zones in all dogs. The clinical significance of patterns at rest requires redefinition.

Animals↗
PubMed1981

Quantitative thallium-201 redistribution with a fixed coronary stenosis in dogs.

The redistribution of thallium-201 (201Tl) after coronary vasodilation was studied in 14 dogs with a proximal stenosis of the left circumflex coronary artery that did not reduce basal flow but attenuated reactive hypermia. During an 8-10-minute i.v. infusion of adenosine, radioactive microspheres and 201Tl were injected into the left atrium. Sequential cardiac scintiscans and microsphere injections permitted subsequent determination of coronary blood flow during the redistribution of 201Tl. After 15-220 minutes of observation, the dogs were killed and the hearts removed for the measurement of the activity of 201Tl and the radioactive microspheres in the normal (left anterior descending coronary artery [LAD]) and flow-restricted (left circumflex coronary artery [LCX]) regions. The ratios of the activity in LAD/LCX for microspheres (TRmic) and for 201Tl (RT1) were compared with the activity ratio determined from the scintiscan (Rscan). Rmic for the microsphere simultaneously injected with 201Tl can be compared with the initial Rscan, which showed a significant hourly decrease from an initial value of 1.26 +/- 0.12 to a mean final value of 1.02 +/- 0.09 by 3-4 hours. The final Rscan (mean 1.07 +/- 0.10) in each experiment also correlated significantly (r = 0.854) with the final true myocardial RT1 (mean 1.26 +/- 0.25). Rscan underestimated Rmic (average 2.25 +/- 0.48) when both 201Tl and microspheres were simultaneously injected; Rscan also underestimated RT1, but the directional changes were similar. A further analysis of the Rmic, Rscan and RT1 in two groups of dogs with either relatively high or low coronary flow during adenosine infusion suggests that the net loss of cellular 201Tl from the normal scintigraphic area is the mechanism underlying the resolution of these initial defects.

Adenosine↗
PubMed1979

Thallium-201 myocardial scintigraphy in patients with triple-vessel disease and ischemic exercise stress tests.

Thirty patients with triple-vessel coronary artery disease proven by angiography, symptomatic angina and a positive ECG stress test were evaluated with thallium-201 (201TI) scintigraphy. Twenty patients also had aortocoronary saphenous vein bypass surgery; 15 of them had repeat noninvasive evaluation. Seventy percent of these patients showed ischemia by 201TI scintigraphy, of which one-half returned to normal after surgery. Postoperative reversion of the ECG stress test together with 201TI stress/reperfusion imaging correlated well with the completeness of surgical revascularization. We could not explain the prevalence (80%) of infarcts detected by 201TI in this group, of which 76% could be anatomically correlated to epicardial scars. The positivity of infarcts by 201TI exceeded that predicted by previous history of infarction, Q waves on resting ECG or ventriculographic akinesis. These observations suggest that 201TI scintigraphy is a useful noninvasive tool in the follow-up and understanding of patients with coronary heart disease. These conclusions also support the concept that 201TI stress imaging need not have the identical connotation as the ECG stress test.

Adult↗
PubMed1977

Scintigraphic diagnosis of ischemic intestine with technetium-99m sulfur colloid-labeled leukocytes.

Positive scintigrams were obtained in 13 of 15 dogs injected with technetium-99m sulfur colloid-labeled leukocytes following the experimental production of intestinal ischemia. The radioactivity of the ischemic intestines averaged 5.9 times that found in normal control segments of intestine from the same animal. Labeled leukocytes may be used as a rapid noninvasive technique for the early identification of ischemic intestine.

Animals↗