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Biomedical subjects

B Richard

Publications and source records attributed to B Richard.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Role of selective venous catheterization with assay of parathormone 1-84 in the treatment of persistent hyperparathyroidism].

From March 1993 to October 1994, 12 patients operated for persistent hyperparathyroidism had preoperative catheterization of large cervical and mediastinal veins (CLCMV) with determination of serum concentration of intact parathyroid hormone. Other localization procedures included: ultrasonography (US, n = 9), computed tomography (CT, n = 8), magnetic resonance imaging (MRI, n = 5), and sestamibi radionuclide imaging (MIBI, n = 9). A (1-84 PTH) gradient of 1-84 PTH was demonstrated in all patients, localizing a lesion in the neck (n = 9) or in the mediastinum (n = 3). An adenoma was found in nine patients either in the neck (n = 6) or in the mediastinum (n = 3), and 2 patients had glandular hyperplasia. Two patients remained hypercalcemic despite the removal of parathyroid tissue during CLCMV-guided reexploration. An other patient underwent unsuccessful neck reexploration. The sensitivity of other procedures was lower: US: 22%, CT: 50%, MRI: 60%, and MIBI: 66.5%. After a median follow-up of 13 months, 9 patients were cured of their hyperparathyroidism (75%) and 3 had persistent hypercalcemia. Our results suggest that CLCMV with 1-84 PTH measurement is the most accurate localization procedure in persistent hyperparathyroidism.

Adult↗
PubMed1996

Values of ultrasonography, sestamibi scintigraphy, and intraoperative measurement of 1-84 PTH for unilateral neck exploration of primary hyperparathyroidism.

Unilateral neck exploration (UNE) is a controversial approach to the treatment of primary hyperparathyroidism (PHP), and most surgeons favor bilateral neck exploration. The aim of this study was to assess the value of ultrasonography, sestamibi scintigraphy, and intraoperative measurement of urinary cyclic AMP (UcAMP) or 1-84 PTH in 200 patients undergoing unilateral neck exploration under local anesthesia. Conditions for UNE were (1) a presumed solitary adenoma detected by ultrasonography, (2) no thyroid disease, and (3) no family history of PHP or multiple endocrine neoplasia. Patient's consent was obtained for conversion to bilateral exploration according to surgical and biologic findings. Sensitivity of ultrasonography was 92.5%. Sestamibi scintigraphy, performed in 70 patients, was less sensitive than ultrasonography (80%). Persistent PHP was accurately detected by intraoperative measurement of UcAMP or 1-84 PTH in all cases. At follow-up, 96.0% of the patients were cured either after unilateral neck exploration only (90.5%), or after conversion into bilateral exploration. Ultrasonography and intraoperative measurement of 1-84 PTH allow unilateral neck exploration with excellent results in a selected group of patients with PHP.

Adenoma↗
PubMed1995

Respiration of amniotic fluid in near-term foetal rabbit.

OBJECTIVE: To examine the existence of amniotic fluid inhalation in foetal rabbit near term. STUDY DESIGN: Rabbit red cells labelled with 51 radio-chromium (Cr51-S1: Injectable solution sodium chromate, volumic activity: 74 MBq/ml; Cis-BioInternational, France) were injected into the amniotic sac of 24 New Zealand White foetal rabbits (mean gestation: 31 days) at day 25 per-laparotomy. At day 26, just prior to caesarean section, human serum albumin labelled with 125 radio-active iode (125I-HSA) (SERALB-125: human serum albumin labelled with radioactive Iode 125, volumic activity: 185 kBq/ml, Cis-BioInternational, France) was injected into each amniotic sac. The lungs, digestive tracts, kidneys and liver were excised separately and radioactivity counted in each organ. RESULTS: On day 26 of gestation, the 51Cr-RC radioactivity rate per gram of tissue in lungs, digestive tract amniotic fluid, liver and kidneys were respectively 1.66 +/- 2.8%, 1.15 +/- 1.6%, 0.015 +/- 0.02% and 0.04 +/- 0.07% of the total amount of radioactivity injected into the amniotic sac at day 25. The lungs' radioactivity was significantly higher than liver (t = 2.94, P < 0.01) or kidneys radioactivity (t = 2.38, P < 0.05). The 125I-HSA injected just prior to caesarean section at day 26 was not found in any foetal organ. CONCLUSIONS: Lung radioactivity is not related to gasps induced by caesarean section, or to a vascular diffusion since lung radioactivity was significantly higher than liver or kidneys' radioactivity. The results of these series of experiments demonstrate that amniotic fluid inhalation does exist in foetal rabbit near term.

Amniotic Fluid↗
PubMed1995

Scaling the feeding mechanism of largemouth bass (Micropterus salmoides): kinematics of prey capture

We present the first analysis of scaling effects on prey capture kinematics of a feeding vertebrate. The scaling of feeding kinematics of largemouth bass (Micropterus salmoides) was investigated using high-speed video (200 fields s-1) to determine what functional changes occur in the feeding mechanism as a consequence of body size. A size series of ten bass ranging from 32 to 210 mm standard length was used for the study and ten feeding sequences from each individual were analyzed to quantify movements of the feeding apparatus during prey capture. Maximal linear and angular displacements of the strike scaled isometrically. The time course of the strike was longer in larger fish. Maximal velocities of displacement were more rapid in larger fish, but their scaling exponents indicated that the intrinsic rate of muscle shortening decreased with fish size. Morphological measurements of the lever arms of the lower jaw and of the two major muscles that drive the feeding mechanism were made to relate possible biomechanical changes in the feeding mechanism to the observed kinematic relationships. The lever arms of the lower jaw and the muscles scaled isometrically; hence, the relative slowing of movements with increasing body size cannot be attributed to changes in mechanical advantage with change in body size. The scaling of feeding kinematics in the largemouth bass is in accord with the scaling of rates of muscle contraction found in other lower vertebrates. These findings demonstrate that body size can have major effects on feeding kinematics and that future comparative studies of feeding kinematics should use empirical data on size effects in kinematic comparisons between taxa.

Journal Article↗
PubMed1995

Scaling the feeding mechanism of the largemouth bass (Micropterus salmoides): motor pattern

We present the first analysis of scaling effects on the motor pattern of a feeding vertebrate. Data are presented for the effects of body size on the pattern of activity in four head muscles during prey capture in the largemouth bass, Micropterus salmoides. Electromyographic (EMG) recordings were made from three expansive-phase muscles (the epaxialis, the sternohyoideus and the levator arcus palatini) and one compressive-phase muscle (the adductor mandibulae), during the capture of small fish prey. Recordings were made of 181 prey-capture events from 19 bass that ranged in size from 83 to 289 mm standard length. We measured seven variables from the myogram of each capture to quantify the temporal pattern of muscle activation, including the duration of activity in each muscle and the onset time of each muscle, relative to the onset of the sternohyoideus muscle. Regressions of the mean value of each variable for the 19 individuals on standard length revealed that only the onset time of the adductor mandibulae changed with fish body size. The increase in onset time of the adductor muscle appears to reflect the longer time taken to open the mouth fully in larger fish. Other research shows that the kinematics of the strike in this species slows significantly with increasing body size. The combined results indicate that the duration of the EMG signal is not directly correlated with the duration of force production in muscles when compared between fish of different sizes. The lack of scaling of burst duration variables suggests that the reduced speeds of prey-capture motion are explained not by changes in the envelope of muscle activity, but rather by the effects of scale on muscle contractile kinetics. These scaling effects may include changes in the relative resistance of the jaw and head structures to movement through water and changes in the intrinsic contractile properties of the muscles of the feeding apparatus.

Journal Article↗
PubMed1994

[Paraneoplastic edema syndromes in acute myelomonocytic leukemia: role of TNF-alpha and IL-6?].

We report the case of a 56 year-old man in remission of a Hodgkin's disease who had an acute myelomonocytic leukemia with major edemas. Chemotherapy temporarily allowed a concomitant regression of edemas, hyperleukocytosis and tumor necrosis factor and interleukin-6 levels which were initially elevated. We discuss the role of these two cytokines in endothelium permeability disorders.

Animals↗
PubMed1994

Isolation of bis-indole alkaloids with antileishmanial and antibacterial activities from Peschiera van heurkii (syn. Tabernaemontana van heurkii).

Extracts from leaves and stem bark of Peschiera van heurkii (Muell. Arg.) L. Allorge (syn. Tabernaemontana van heurkii Muell. Arg., Apocynaceae) have been assayed for antileishmanial and antibacterial activities. The activities were concentrated in the alkaloid fractions which yielded 20 indole and bisindole alkaloids. The strongest leishmanicidal and antibacterial activities were observed with the dimeric alkaloids conodurine (1), N-demethylconodurine (= gabunine) (2), and conoduramine (3). Weak toxicity towards macrophage host cells and strong activity against the intracellular amastigote form of Leishmania were observed for compounds 1 and 2. In vivo, 1 was less active than glucantime (= N-methylglucamine antimonate), the drug of reference, while 2 was devoid of activity at 100 mg/kg.

Alkaloids↗
PubMed1994

[Surgery of primary hyperparathyroidism by unilateral approach under local anesthesia and intraoperative determination of PTH 1-84].

Between July 89 and June 92, 70 patients with primary hyperparathyroidism underwent adenomectomy by unilateral incision under local anesthesia (Ul/LA), without exploration of the remaining glands. The procedure was carried out with intraoperative monitoring of urinary cyclic AMP (n = 35), Calcemia was measured 6-monthly for one year in every patient. 62 (88.6%) patients were cured after Ul/LA, whereas 5 patients required conversion to bilateral cervicotomy under general anesthesia because of abnormal hormonal levels, thus giving an overall success rate of 97% (67/70). The reasons for treatment failure of Ul/LA included misleading conclusions of cervical ultrasonography (n = 5), agitation of the patient (n = 1) and deep localization of the adenoma (n = 1). When cervical ultrasonography is suggestive of a parathyroid adenoma in expert hands, the probability of a second localization or associated hyperplasia is very low, so that adenomectomy by Ul/LA can be attempted safely, provided that the serum level of intact parathyroid hormone returns to normal values within one hour following resection. In our experience, parathyroidectomy by Ul/LA should not be considered in case of non conclusive ultrasonography, familial history pf hyperparathyroidism of MEN-I, ultrasonic evidence of several enlarged glands or associated thyroid nodule requiring simultaneous treatment.

Adult↗
PubMed1992

Monensin action on the Golgi complex in perfused rat liver: evidence against bile salt vesicular transport.

Several studies suggest that bile salts are transported from the basolateral to the canalicular membrane of hepatocytes by a vesicular pathway, possibly in part via the Golgi complex. To test this hypothesis, the present study examined, in the perfused rat liver, the influence of the Na+ ionophore monensin on the biliary secretion of taurocholate and biliary lipids. The effects of the drug have been checked by the study of the ultrastructural modifications of the Golgi complex, secretion of horseradish peroxidase, and bile salt uptake. An infusion of monensin (1, 3, or 5 mumol/L) into the liver induced considerable swelling of the Golgi complex within 5 minutes. After a bolus injection of horseradish peroxidase during monensin infusion, the biliary secretion of the protein was delayed (1 mumol/L monensin) and markedly reduced (5 mumol/L monensin). Bile salt uptake was virtually unchanged except with 5 mumol/L monensin. This suggests that monensin has the same effects on the subcellular traffic in the perfused liver as in cultured cells. After a bolus injection of taurocholate (0.25, 5.0, or 8.5 mumol/100 g body wt) during monensin infusion, the pattern of biliary secretion of the bile salt was identical to that of controls. During continuous infusion of taurocholate, a 10-minute monensin infusion (1 or 3 mumol/L) had no effect on the biliary secretion of taurocholate and on the secretion of lecithin and cholesterol induced by taurocholate. High concentrations (5 mumol/L) or prolonged infusions (20 minutes) of monensin decreased the biliary secretion of bile salts but corresponded to a marked decrease of taurocholate uptake. In summary, the Na+ ionophore monensin altered the Golgi complex and the vesicular transport of horseradish peroxidase, whereas taurocholate biliary secretion was not influenced unless taurocholate biliary secretion was not influenced unless taurocholate uptake by the liver was markedly decreased. It may be concluded that taurocholate and biliary lipid secretion, under these conditions, does not depend essentially on pathways involving acidic transporting vesicles and particularly the trans-Golgi complex.

Animals↗
PubMed1992

Pharmacokinetics of mitoxantrone in cancer patients treated by high-dose chemotherapy and autologous bone marrow transplantation.

We have studied the pharmacokinetics of mitoxantrone in cancer patients. Two regimens were used: eight women (10 kinetics) received a 10 min i.v. infusion of 12 mg m-2 of mitoxantrone; seven women (seven kinetics) received high-dose mitoxantrone associated to high-dose alkylating agents and underwent autologous bone marrow transplantation (BMT). High-dose mitoxantrone was administered according to two different protocols. The drug was quantified in plasma with an HPLC assay and pharmacokinetic analysis was performed with the APIS software. Mitoxantrone pharmacokinetics were best described by an open two- (six kinetics) or an open three compartment model (11 kinetics). A large interindivual variability was observed in pharmacokinetic parameters. In the first group of patients, mean +/- s.d. values of clearance, half-life and total distribution volume were 21.41 +/- 14.59 1 h-1, 19.83 +/- 23.95 h, 165.89 +/- 134.75 1 respectively. In the high-dose group, these values were 21.68 +/- 7.30 1 h-1, 50.26 +/- 20.62 h, 413.70 +/- 194.81 1 respectively. Results showed that identification through the open 2-compartment model is certainly related to the small number of late time-points. We therefore think that mitoxantrone pharmacokinetics is generally best described by an open 3-compartment model. Clearance values showed that there was no saturation in mitoxantrone elimination, even at the highest doses. Terminal elimination half-life was probably underestimated because of the lack of late time-points in some kinetics. The half-life is long for patients receiving high-dose mitoxantrone (mean value was 50 h) and it would be hazardous to perform BMT too early after mitoxantrone infusion. Mitoxantrone metabolites were detected in the plasma of five patients receiving high-dose mitoxantrone and in one with hepatic impairment.

Adolescent↗
PubMed1992

[Antimalarial effect of n-hentriacontanol isolated from Cuatresia sp (Solanaceae)].

The antimalarial activity of the fatty alcohol, n-hentriacontanol, isolated from the bolivian Solanaceae, Cuatresia sp, is investigated in vivo through a classical four-day suppressive test against Plasmodium berghei and P. vinckei in mice. This product markedly reduced the virulence of experimentally induced P. vinckei infection. n-Hentriacontanol belongs to a new class of antimalarial natural compounds to be exploited for therapeutic purposes.

Animals↗
PubMed1991

[Excision under local anesthesia of parathyroid adenomas. Criteria of selection and control of effectiveness. 35 cases].

Primary hyperparathyroidism caused by an adenoma that has been identified and localized by ultrasonography can be treated through a limited approach route, under local anaesthesia, provided the effect of excision is controlled by a perioperative assay of urinary cAMP or, preferably, of plasma parathormone level, and provided the contra-indications of this method are respected. Thirty-three out of 35 patients have been successfully operated upon by this method. In case of failure confirmed by laboratory tests, local anaesthesia was only a prelude to cervicotomy under general anaesthesia.

Adenoma↗
PubMed1991

Interspecies variability in mitoxantrone metabolism using primary cultures of hepatocytes isolated from rat, rabbit and humans.

Metabolism of mitoxantrone was studied in primary cultures of hepatocytes freshly obtained from rat, rabbit and humans. Metabolic pattern was evaluated by a high performance liquid chromatographic method which specifically resolved mitoxantrone from its mono- and dicarboxylic acid derivatives. Studies were carried out over 48 hr and at [14C]mitoxantrone concentrations ranging between 1 and 20 microM. In all species studied, metabolism occurred: extracellular unchanged mitoxantrone concentrations represented around 50, 25 and 20% of total extracellular radiolabel at 48 hr in rat, rabbit and humans, respectively. Although minor interspecies variability was observed in total amount of drug biotransformed by hepatocytes, large variability in the metabolic pattern occurred between the different species: hence, in rats the main derivatives were two polar compounds and only trace amounts of the mono- and dicarboxylic acid metabolites were present. In both rabbits and humans however, these polar derivatives represented minor metabolic pathways and the main metabolites were the mono- and dicarboxylic acid derivatives. While the percentage of total biotransformation was similar in these two latter species, the monocarboxylic acid derivative was the main metabolite in rabbits while the dicarboxylic acid was predominant in humans. Only small interindividual differences (N = 4) were observed in the metabolism of mitoxantrone by human hepatocytes in primary culture. These data demonstrated that: (i) in all species, mitoxantrone was biotransformed into metabolites which rapidly effluxed in the extracellular compartment, (ii) there were low interspecies differences between rat, rabbit and humans in terms of total biotransformed drug, but (iii) large interspecies variability was demonstrated in the qualitative (rat versus both rabbit and human) and relative (rabbit versus man) patterns of the metabolites. Furthermore, the metabolism of mitoxantrone was linear over a wide range of concentrations (i.e. 1-20 microM). In conclusion, rabbit appears to be the animal species most closely related to humans in terms of mitoxantrone metabolism.

Animals↗
PubMed1991

[Group therapy in anorexia nervosa (apropos of a literature review)].

Group therapy is based on mediated interindividual relationships and therefore represents a serious challenge for the treatment of anorexia nervosa patients, because the first effect of this type of treatment is to exacerbate relational difficulties. Nevertheless, starting after the crisis period, group therapy has demonstrated its interest in a multimodal intervention and its relevance as a treatment associated with individual therapy. The author regrets that this technique is rarely used and suggests that its rejection is based on a priori opinions more than on actual experience.

Anorexia Nervosa↗