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R Boucher

Publications and source records attributed to R Boucher.

At least 19 recordsLinked to original sources
PubMed1997

Noncoordinated expression of alpha-, beta-, and gamma-subunit mRNAs of epithelial Na+ channel along rat respiratory tract.

Na+ reabsorption from the epithelial surface of the respiratory tract plays a fundamental role in respiratory physiology. As in the epithelia of the renal collecting tubule and distal colon, Na+ enters across the luminal surface of respiratory epithelial cells via a recently cloned amiloride-sensitive multisubunit (alpha, beta, gamma) epithelial Na+ channel. We have examined the cellular expression at the mRNA level of the alpha-, beta-, and gamma-subunits of rat epithelial Na+ channel (rENaC) in the rat lung and upper airway epithelial cells using in situ hybridization. A large prevalence of alpha- and gamma-rENaC subunit expression (over beta) was found in tracheal epithelium, in a subpopulation of alveolar cells, presumably type II pneumocytes, and in nasal and tracheal gland acini. In contrast, equivalent levels of expression of all three subunits were detected in bronchiolar epithelium and in rat nasal gland ducts. This diversity of expression may reflect cell-specific functions of the amiloride-sensitive Na+ channel along the respiratory tract.

Animals↗
PubMed1996

Early death due to defective neonatal lung liquid clearance in alpha-ENaC-deficient mice.

The amiloride-sensitive epithelial sodium channel, ENaC, is a heteromultimeric protein made up of three homologous subunits (alpha, beta and gamma) (1,2). In vitro, assembly and expression of functional active sodium channels in the Xenopus oocyte is strictly dependent on alpha-ENaC--the beta and gamma subunits by themselves are unable to induce an amiloride-sensitive sodium current in this heterologous expression system (2). In vivo, ENaC constitutes the limiting step for sodium absorption in epithelial cells that line the distal renal tubule, distal colon and the duct of several exocrine glands. The adult lung expresses alpha, beta and gamma ENaC (3,4), and an amiloride-sensitive electrogenic sodium reabsorption has been documented in upper and lower airways (3-7), but it is not established whether this sodium transport is mediated by ENaC in vivo. We inactivated the mouse alpha-ENaC gene by gene targeting. Amiloride-sensitive electrogenic Na+ transport was abolished in airway epithelia from alpha-ENaC(-/-) mice. Alpha-ENaC(-/-) neonates developed respiratory distress and died within 40 h of birth from failure to clear their lungs of liquid. This study shows that ENaC plays a critical role in the adaptation of the newborn lung to air breathing.

Animals↗
PubMed1994

Excitotoxic lateral pallidotomy does not relieve L-dopa-induced dyskinesia in MPTP parkinsonian monkeys.

We attempted to relieve the marked overactivity known to occur in the lateral segment of the globus pallidus (GPL) in L-DOPA-induced dyskinesia (LID) by unilateral stereotaxic ibotenic acid lesioning of the GPL in 4 monkeys with MPTP-induced parkinsonism. Two already dyskinetic animals were pallidotomized to counteract LID once established, while 2 L-DOPA-naive MPTP-treated animals were pallidotomized before L-DOPA was ever administered in an attempt to prevent the development of the process conductive to LID. Acutely after the lesion, more prominent akinesia (particularly in the contralateral limbs) with contraversive body deviation and circling behavior were seen for 48 h. Flexor posturing of the contralateral forelimb persisted to a variable degree. When L-DOPA treatment was resumed or instituted 1 week postoperatively, ipsiversive circling behavior occurred in all animals and contralateral dyskinesia worsened in 3, whether L-DOPA or a selective dopamine D2 agonist was administered. Lesions in these 3 cases were fairly restricted to the GPL histologically. One monkey kept L-DOPA-naive before pallidotomy never developed LID contralaterally to the lesion despite treatment for several months. The lesion this time involved the entire GP. The fact that ablation of the GPL worsened LID suggests that a complex rearrangement of the balance of functional capacity between the GP and the subthalamic nucleus takes place in LID which is not amenable to correction merely by a lateral pallidotomy. Our observations also suggest that functional redundancy exists in striatopallidal circuits and that no single pathway is responsible for LID.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1993

In vitro micronucleus bioassay of human peripheral lymphocytes for adriamycin in the presence of cyclophosphamide and urines of patients administered anticancer drugs.

The aim of this study was to develop an in vitro human peripheral lymphocyte micronucleus bioassay involving phytohemagglutinin stimulant for urines containing adriamycin (ADR) and cyclophosphamide (CP). In vitro studies with defined concentrations of ADR, CP, and fresh urine showed that mitotic indices and micronuclei counts/1,000 cells had to be log (X + 1) transformed to be able to use parametric statistics and that a specific micronucleus assay for ADR in the presence of CP and urine for 5-15 ng ADR/mL had been developed. Whereas CP alone could be detected between 196-522 micrograms/mL, this effect was abolished in the presence of 15 ng ADR/mL. Interdonor variabilities relative to ADR sensitivity and CP linear dynamic range were marked, but intradonor variability was small. The MN bioassay tolerated < 10% urine. Results for urines from nine patients receiving antineoplastic drugs (CP, all; ADR, 3; 5-fluorouracil, 3; methotrexate, 3; vincristine, 4; procarbazine, 1; and megestrol acetate, 1) showed that only 1/3 patients given ADR were detected, and two others not given ADR were positive. All frozen urines from the 12 control subjects and the nine patients exhibited depressed mitotic index, with, however, no control patient urines inducing increased micronuclei. Two patients had urines of undefined genotoxic potential since undepressed mitotic indices were not attainable by dilution. The effects of combination chemotherapy in addition to freezing and storage influences were complex. More research is required to be able to interpret the results.

Analysis of Variance↗
PubMed1993

Effect of adding the D1 agonist CY 208-243 to chronic bromocriptine treatment. I: Evaluation of motor parameters in relation to striatal catecholamine content and dopamine receptors.

A group of four cynomolgus monkeys previously rendered parkinsonian by the toxin 1-methyl-4-phenyl,1,2,3,6-tetrahydropyridine (MPTP) were observed in locomotion cages equipped with photocells during four periods of 7 days during which they received saline or two doses of the D1 agonist CY 208-243. The larger dose of 0.5 mg/kg produced a significant increase in locomotion in three of four animals. A second group of eight monkeys also previously rendered parkinsonian by MPTP and having received no other treatment were given a daily treatment of bromocriptine 1.66 mg/kg orally daily during 4 weeks. In four of the animals, after a week on bromocriptine alone, the D1 agonist CY 208-243 was added in increasing doses of 0.05, 0.1, and 0.5 mg/kg. The motor response as measured by locomotion, hand dexterity, and a disability score improved progressively at least in some of the animals on bromocriptine alone. The addition of CY 208-243 produced a more striking improvement of all three parameters, which appeared to be dose dependent. Biochemical analysis of the brain of these animals plus one control and one MPTP untreated monkey showed a > 90% loss of dopamine in the striatum in six of the eight treated monkeys. Both D2 and D1 dopamine receptors were increased in density by denervation, but both treatments abolished this increase for the D2 receptors while increasing the affinity of the D1 receptors.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Isobutylmethylxanthine fails to stimulate chloride secretion in cystic fibrosis airway epithelia.

It has been proposed that a combination of an activated adenylyl cyclase and a high concentration of a phosphodiesterase inhibitor (isobutylmethylxanthine [IBMX], 5 mM) stimulates Cl- secretion mediated by the heterologously expressed cystic fibrosis transmembrane regulator protein carrying the most common cystic fibrosis (CF) mutation (delta F508). We tested whether Cl- secretion could be stimulated by this protocol in vitro and in vivo in CF airway epithelia expressing endogenous delta F508 CFTR protein. In cultured airway preparations, forskolin (a direct adenylyl cyclase activator) stimulated Cl- secretion in amiloride-pretreated normal (delta Isc = 7.1 +/- 1.7 microA.cm-2) but not CF tissues (delta Isc = -02 +/- 0.1 microA.cm-2). Unexpectedly, IBMX partially inhibited the forskolin-induced Cl- secretion in normal tissues; IBMX addition had no effect on CF tissues. Direct measurements of cell cAMP concentrations revealed that 0.1 mM IBMX and forskolin produced the maximum levels of cell cAMP levels attainable with this drug combination, and 5 mM IBMX was without further effect. The combination of forskolin (10(-5) M) and isoproterenol, an adenylyl cyclase activator (10(-5) M), produced approximately 3 times higher levels of cAMP than forskolin/IBMX but also did not induce Cl- secretion in CF tissues. Studies of Cl- secretion in vivo, assessed by the transepithelial electric potential difference (PD), showed that isoproterenol (10(-5) M) stimulated Cl- secretion (delta PD = -16.3 +/- 4.3 mV; n = 4) in nasal epithelia of normal subjects but not in CF patients homozygous for the delta F508 mutation (delta PD = -2.6 +/- 1.9 mV; n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1992

Effect of LY 171555 and CY 208-243 on tremor suppression in the MPTP monkey model of parkinsonism.

The antitremor effect of the D2 agonist LY 171555 and of the D1 agonist CY 208-243 alone and in combination was tested in a monkey previously rendered parkinsonian by MPTP and displaying exceptionally a rest tremor in the limbs. The D2 agonist suppressed rest tremor in a dose-dependent fashion. The D1 agonist by itself had no effect but it potentiated the effect of a small dose of LY 171555.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1992

Effect of ethosuximide on rest tremor in the MPTP monkey model.

Based on the hypothesis that low-threshold calcium conductance in the thalamus might be involved in the pathophysiology of parkinsonian tremor, ethosuximide was given chronically to a monkey previously treated with MPTP and displaying exceptionally a typical rest tremor. After 5 days of daily treatment, the tremor was reduced by 60%. Diltiazem and verapamil which act on different calcium channels had no such effect. Ethosuximide also potentiated the anti-tremor effect of the dopamine D2 agonist LY-171555.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

Effect of clonidine and atropine on rest tremor in the MPTP monkey model of parkinsonism.

The purported alpha 2-adrenergic agonist clonidine was found to inhibit rest tremor at doses of 0.023-0.1 mg/kg in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine monkey model of parkinsonism. The effect was dose dependent, but sedation and reduced mobility were observed. Atropine at doses of 0.1-1 mg/kg also reduced tremor in a dose-dependent fashion, but side-effects in the form of agitation, dilated pupils, and dry mouth were seen. When the two drugs were combined, however, we saw a significant potentiation of the antitremor effect. We could even abolish tremor with doses of atropine and clonidine that by themselves were without effect. The side-effects were almost eliminated by the combination.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

Expression of mucin synthesis and secretion in human tracheobronchial epithelial cells grown in culture.

The effects of culture conditions on growth and differentiation of human tracheobronchial epithelial (HTBE) cells have been defined. Epithelial cells were dissociated from tissues by protease treatment and were plated on tissue culture dishes in F12 medium supplemented with insulin, transferrin, epidermal growth factor, hydrocortisone, cholera toxin, bovine hypothalamus extract, and retinol. HTBE cells did not express any mucociliary function (ciliogenesis or mucin secretion) on tissue culture plastic, but they could be passaged 3 to 5 times with a total of 10 to 25 population doublings. Cells from early passages re-express both these functions when transplanted to tracheal grafts. When tissue culture plates were coated with collagen film or collagen gel substrata, cell attachment and proliferation were stimulated. However, the expression of mucous cell function in culture occurred only when cells were plated on collagen gel substrata and vitamin A (retinol) was present in the medium. Mucous cell differentiation under optimal conditions was defined by ultrastructural studies, by immunologic studies with mucin-specific monoclonal antibodies, and by carbohydrate and amino acid compositional analyses of mucin-like glycoproteins purified from culture medium. These results demonstrate for the first time that HTBE cells can express mucin synthesis and secretion under appropriate culture conditions.

Amino Acids↗
PubMed1989

Effect of D1 receptor stimulation in normal and MPTP monkeys.

The effect of a selective agonist of the dopamine D1 receptor (SKF 38393) and of the D2 receptor (LY-171555) was tested acutely in normal and in monkeys with a parkinsonian syndrome induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The D2 agonist induced a strong locomotor response and lingual dyskinesia in both normal and parkinsonian monkeys. The D1 agonist however had no locomotor effect by itself but induced tongue protrusions in normal monkeys only. It appeared to potentiate the dyskinetic effect of LY 171555 in MPTP monkeys but it antagonized the locomotor action of the D2 agonist in both normal and MPTP monkeys. The selective D1 and D2 antagonists SCH 23390 and sulpiride were also tested. Both compounds were able to suppress the dyskinetic action of the combined agonists in normal animals but only the D2 antagonist was effective in the same conditions in MPTP monkeys. These findings emphasize the importance of the D2 receptor in mediating the locomotor response as well as dyskinesia in monkeys.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1989

Phenytoin prodrug: preclinical and clinical studies.

The currently available phenytoin (PHT) solution has many disadvantages stemming from poor aqueous solubility of PHT. A novel approach to solve the problem has been the synthesis of a phosphate ester of PHT (PHT prodrug ACC-9653). This water-soluble compound is metabolized rapidly into PO4 and PHT. A four center open-label, baseline-controlled study of 43 patients with epilepsy maintained on oral twice-daily PHT monotherapy was performed to evaluate the safety and pharmacokinetic profile of the prodrug. Patients received an i.v. or i.m. dose of ACC-9653 at a dose equivalent to the patients' morning dose of PHT. Intravenous dosages were infused at a rate of 75 mg/min, and i.m. dosages were given as one or two injections. After a period of 6 days, during which patients were again maintained with oral PHT, they were given a dose of ACC-9653 via whichever route they had not yet received. The Tmax of the prodrug averaged 5.7 and 36 min (0.095 and 0.606 h) after i.v. and i.m. administrations, respectively. The elimination half-life of ACC-9653 (conversion from prodrug to PHT) after i.v. and i.m. administration was 8.4 and 32.7 min (0.140 and 0.545 h), respectively, and both were independent of the dose. The plasma clearance of ACC-9653 was not dependent on dose or route of administration and averaged 19.8 +/- 1.16 and 17.8 +/- 0.83 L/h after i.v. and i.m. administrations, respectively. The area under curve ratio of PHT after i.m. and i.v. ACC-9653 was 1.17 +/- 0.13 which was not significantly different from 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Behavioral and biochemical effect of chronic treatment with D-1 and/or D-2 dopamine agonists in MPTP monkeys.

Monkeys developed a severe parkinsonian syndrome after intravenous administration of (MPTP). L-DOPA/carbidopa (D-1 and D-2) or bromocriptine (D-2) treatment relieved the parkinsonian symptoms, whereas SKF 38393 (D-1) was ineffective. No dyskinesia was seen in monkeys receiving bromocriptine or SKF 38393 as opposed to the L-DOPA-treated animals, in which the dyskinetic response appeared to increased with time. MPTP induced a significant increase (25%, P less than 0.01) in the number of [3H]spiperone binding sites (Bmax) in the caudate nucleus and in putamen. The Bmax of spiperone binding in the L-DOPA-treated monkeys was on average 18% lower (P less than 0.01) than that of the animals treated with MPTP alone. The Bmax for the bromocriptine-treated group was 29% (P less than 0.01) less than that in the MPTP-treated group or 11% (P less than 0.05) less than that in the L-DOPA-treated monkeys. The SKF 38393 treatment induced a 23% (P less than 0.01) decrease in the Bmax as compared to that of animals treated with MPTP alone, and no significant change compared to the L-DOPA- or bromocriptine-treated animals. These results suggest that stimulation of D-1 and D-2 dopamine receptors can differently influence the mechanisms controlling dopamine agonist-induced dyskinesia in MPTP-treated monkeys.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

Chloroprene and isoprene: cytogenetic studies in mice.

Groups of male B6C3F1 mice (n = 15) were exposed for 6 h per day to ambient air, to chloroprene (12, 32, 80, 200 p.p.m.) or to isoprene (438, 1750 and 7000 p.p.m.) on 12 days. These compounds are the 2-chloro and the 2-methyl analogues, respectively, of 1,3-butadiene, a genotoxic and carcinogenic chemical in B6C3F1 mice. Exposure to chloroprene resulted in a 100% incidence of mortality among the mice exposed to 200 p.p.m. At concentrations of 80 p.p.m. and below, chloroprene neither induced a significant increase in chromosomal aberrations (CA), sister chromatid exchanges (SCE) or micronucleated erythrocytes, nor significantly altered the rate of erythropoiesis or of bone marrow cellular proliferation kinetics. However, the mitotic index (MI) in the bone marrow of chloroprene-exposed mice was significantly increased. Under similar conditions, exposure to isoprene induced significant increases at all concentrations in the frequency of SCE in bone marrow cells and in the levels of micronucleated polychromatic erythrocytes (PCE) and of micronucleated normochromatic erythrocytes in peripheral blood. In addition, a significant lengthening of the bone marrow average generation time and a significant decrease in the percentage of circulating PCE was detected. However, exposure to isoprene did not induce in bone marrow a significant increase in the frequency of CA nor did the exposure significantly alter the MI. The dose-response curves for SCE and micronuclei induction were non-linear, appearing to saturate at 438 and 1750 p.p.m., respectively. These results suggest that, similarly to butadiene, inhaled isoprene can be expected to induce tumors at multiple sites in B6C3F1 mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Assessment of maximal expiratory pressure in healthy adults.

Maximal static expiratory pressure developed at the mouth (PEmax) provides a useful clinical index of expiratory muscle function; however, the range of normal values among laboratories shows considerable variation. We examined the hypothesis that the wide variability could be attributable to the differences in technique among laboratories. We measured PEmax at functional residual capacity (PEmax FRC) in 28 healthy subjects using the following five techniques: 1) using a scuba-type mouthpiece with the cheeks supported by the hands ("hands on"), 2) without supporting the cheeks ("no hands"), 3) using a rigid, circular mouthpiece (2.8 cm ID, "tube"), 4) using the scuba-type mouthpiece but with the cheeks supported by an observer ("other hands"), and 5) using a large-bore circular mouthpiece (4.1 cm ID, "new tube"). Mean PEmax FRC obtained with hands on was significantly higher than no-hands and tube methods. PEmax FRC values obtained by the other-hands and new-tube maneuvers were similar to the hands-on maneuver. We conclude that the technique used to measure PEmax FRC can significantly affect the results and suggest that it should be measured using a large-bore circular mouthpiece or a scuba-diving mouthpiece with the cheeks supported.

Adult↗
PubMed1988

The introduction of biologically active foreign genes into human respiratory epithelial cells using electroporation.

A simple method for introducing genes into respiratory epithelial cells would assist molecular studies of a variety of pulmonary disorders. Several different techniques for introducing foreign DNA into cells have been described but have either not been useful for respiratory epithelial cells or are difficult and cumbersome to perform. Electroporation is a simple technique that consists of exposing a cell-DNA suspension to an electric shock. Although it has been used to introduce genes into a variety of cell types, it has not previously been applied to respiratory epithelial cells. Human nasal epithelial cells were transfected with the plasmid pRSVCAT, which is an expression vector containing the origin of replication of pBR322 coupled to the Rous sarcoma virus (RSV) long terminal repeat (LTR) region driving the coding sequence for the chloramphenicol acetyltransferase (CAT) gene. The CAT gene is useful for determining optimal conditions for electroporation since it is not normally present in eukaryotic cells, and CAT activity correlates with the level of CAT mRNA; this provides a measure of expression of introduced foreign genes. Successful expression of the CAT gene was demonstrated by electroporation, whereas calcium phosphate transfection resulted in very low CAT activity. Optimal conditions for electroporation of respiratory epithelial cells were determined. Electroporating nasal epithelial cells using 500 volts, a DNA concentration of 10 micrograms/ml, and a sucrose buffer yielded the highest CAT activity, which peaked at 48 h after electroporation.

Avian Sarcoma Viruses↗
PubMed1988

[Animal models of tardive dyskinesia].

It is possible to induce in monkeys abnormal movements of the mouth and tongue resembling strikingly tardive dyskinesia. Such movements can be induced by chronic treatment with neuroleptics or by lesions placed in the habenular interpeduncular tract or nucleus parafascicularis thalami. Dopaminergic D1 and D2 receptors are involved in the modulation of such movements.

Animals↗