NMR studies of phase separation of a binary liquid in a porous glass.
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Journal Article↗
Biomedical subjects
L Tremblay
Publications and source records attributed to L Tremblay.
Activity of pallidal neurons in the monkey during dyskinesia induced by injection of bicuculline in the external pallidum.
The present study was undertaken to determine whether dyskinesia, resulting from injection of the GABA antagonist bicuculline into the external globus pallidus of intact monkeys, is induced by hyperactivity of local external pallidal neurons and ensuing hypoactivity of neurons in the internal globus pallidus, at the output of the basal ganglia. Accordingly, 86% of responding external pallidal neurons increased and 56% of internal pallidal neurons decreased their activity, either exclusively or within biphasic responses. Whereas 29% of external pallidal neurons decreased and as much as 85% of internal pallidal neurons increased their activity. The latter unpredicted responses may be explained by diffusion of bicuculline from the external to the internal pallidum and by lateral monosynaptic inhibition within the external and its mirror image in the internal pallidum. With respect to individual injection sites, the hypoactive neurons in the internal pallidum tended to be grouped together and surrounded by hyperactive or unresponsive neurons. The changes occurred before and persisted during dyskinesia, suggesting that they were required to induce and maintain the dyskinesia. There were also changes in firing patterns, comprising long periods of silence, especially in external pallidal neurons close to the injection site. The periods of silence did not appear to result from depolarization block but rather from activation of receptors of inhibitory neurotransmission other than type A GABA. Dyskinesia therefore does not appear to result exclusively from a simple imbalance of activity between the pallidal segments, with hyperactivity in the external and hypoactivity in the internal segment, but also from imbalances within each pallidal segment, possibly with a center-surround organization.
Action Potentials↗
Electrical slow wave activity of the cat stomach: its frequency gradient and the effect of indomethacin.
The present study was performed to establish the intrinsic frequency of the slow waves in different regions of the cat stomach, to define the propagation velocity of the slow wave along the stomach, and to determine whether endogenous prostaglandins can affect the slow wave frequency. In 20 cats, electrical activity was recorded from the anterior wall of the intact stomach in vivo and in vitro, and in vitro after cutting the stomach into 16 pieces to isolate each pair of electrodes. In vivo, slow waves (4.1 +/- 0.5 cpm) were seen only from mid corpus to pylorus, the apparent propagation velocity decreasing towards the antrum. In vitro: (a) after cutting, the slow wave frequency increased, to a maximum in 1 h (12 +/- 1.8 cpm; range 10.2-17.3), with the highest frequency always in the mid or orad corpus, usually on the greater curvature (GC), (b) with indomethacin (10(-5) M) the increase in slow wave frequency was prevented or reversed, and there was a frequency gradient with the highest frequency (4.4 +/- 1.2 cpm) uniformly located in the most proximal active site on the GC, and (c) slow waves on the GC were more stable, regular and continuous than on the lesser curvature (LC), the difference being most evident in the corpus. The results suggest that the cat stomach behaves as a system of electrically coupled oscillators of different frequencies. The dominant oscillator of highest frequency is situated in the proximal corpus of the GC, with the remainder of the distal stomach entrained at this frequency. All gastric slow wave oscillators can be driven to higher frequencies by endogenous prostaglandins. The decreasing velocity of slow wave propagation distally suggests that oscillator properties and/or coupling among oscillators differs in the cat.
Animals↗
[A systems approach to teaching intravenous therapy].
Nursing students at the college level must master specific techniques related to their profession. Some techniques, including those associated with intravenous (I.V.) therapy, present unique learning challenges because of their complexity. This article offers a teaching strategy based on the main scientific principles of I.V. therapy. The authors recommend a systems-based approach that was successfully tested by nursing students during the theoretical portion of their studies. This strategy relies on the use of concepts, experimental learning, simulation and role playing. The theory portion uses diagrams to establish links between the various subjects and concepts initially learned by the student. Then, based on the individual's learning processes, more specific information is added during the motivation, acquisition and performance phases. The article elaborates on the development of this strategy.
Education, Nursing, Baccalaureate↗
Médicarte software developed for the Quebec microprocessor health card project.
The Quebec Patient Smart Card Project is a Provincial Government initiative under the responsibility of the Rgie de l'assurance-maladie du Québec (Quebec Health Insurance Board). Development, implementation, and assessment duties were assigned to a team from Université Laval, which in turn joined a group from the Direction de la santé publique du Bas-St-Laurent in Rimouski, where the experiment is taking place. The pilot project seeks to evaluate the use and acceptance of a microprocessor card as a way to improve the exchange of clinical information between card users and various health professionals. The card can be best described as a résumé containing information pertinent to an individual's health history. It is not a complete medical file; rather, it is a summary to be used as a starting point for a discussion between health professionals and patients. The target population is composed of persons 60 years and over, pregnant women, infants under 18 months, and the residents of a small town located in the target area, St-Fabien, regardless of age. The health professionals involved are general practitioners, specialists, pharmacists, nurses, and ambulance personnel. Participation in the project is on a voluntary basis. Each health care provider participating in the project has a personal identification number (PIN) and must use both an access card and a user card to access information. This prevents unauthorized access to a patient's card and allows the staff to sign and date information entered onto the patient card. To test the microprocessor card, we developed software based on a problem-oriented approach integrating diagnosis, investigations, treatments, and referrals. This software is not an expert system that constrains the clinician to a particular decisional algorithm. Instead, the software supports the physician in decision making. The software was developed with a graphical interface (Windows 3.1) to maximize its user friendliness. A version of the software was developed for each of the four groups of health care providers involved. In addition we designed an application to interface with existing pharmaceutical software. For practical reasons and to make it possible to differentiate between the different access profiles, the information stored on the card is divided in several blocks: Identification, Emergency, History (personal and family), Screening Tests, Vaccinations, Drug Profile, General follow-up, and some Specific follow-ups (Pregnancy, Ophthalmology, Kidney failure, Cardiology, Pediatrics, Diabetes, Pneumology, Specific parameters). Over 14,000 diagnoses and symptoms are classified with four levels of precision, the codification being based on the ICPC (International Classification for Primary Care). The software contains different applications to assist the clinician in decision making. A "Drug Advisor" helps the prescriber by detecting possible interactions between drugs, giving indications (doses) and contraindications, cautions, potential side-effects and therapeutic alternatives. There is also a prevention module providing recommendations for vaccination and periodic examinations based on the patient's age and sex. The pharmaceutical, vaccination, and screening tests data banks are updated every six months. These sections of the software are accessible to access card holders at any times, even without a patient card, and constitute in themselves an interesting clinical tool. We developed a software server (SCAM) allowing the different applications to access the data in a memory card regardless of the type of memory card used. Using a single high level command language, this server provides a standardized utilization of memory cards from various manufacturers. It ensures the compatibility of the applications using the card as a storage medium. (abstract truncated)
Aged↗
Nitric oxide mediates inhibitory nerve effects in human esophagus and lower esophageal sphincter.
The effect of inhibition of nitric oxide synthase on nonadrenergic, noncholinergic nerve-mediated responses in circular smooth muscle of the human esophageal body and lower esophageal sphincter (LES) was examined in vitro. Tissues were obtained from 10 patients (eight esophageal resection for cancer, two transplant donors). Muscle strips from the LES developed significant spontaneous tension (11.6 +/- 2.1 mN/mm2, N = 6) and relaxed in response to electrical stimulation. The nitric oxide synthase inhibitor, N omega-nitro-L-arginine (NNA), at 10(-5) M, inhibited the relaxation, but had no significant effect on the spontaneous tension (13.0 +/- 2.6 mN/mm2, P = 0.07). Esophageal body strips developed little spontaneous tension, demonstrated an "off" contraction following the cessation of the electrical stimulus, and when contracted with 10(-5) M carbachol, relaxed during electrical stimulation. NNA (10(-5) M) inhibited the off contraction and the relaxation seen after carbachol and unmasked a prominent intrastimulus contraction. This intrastimulus contraction was enhanced by eserine and inhibited by atropine and tetrodotoxin. NNA showed similar potency in the esophageal body and LES and its effects were reversed by L-arginine, but not D-arginine. The results indicate that nitric oxide is an important mediator for nonadrenergic, noncholinergic nerve effects in the human esophagus and lower esophageal sphincter.
Amino Acid Oxidoreductases↗
Cholinergic responses in the cat lower esophageal sphincter show regional variation.
BACKGROUND/AIMS: The lower esophageal sphincter (LES) pressure in humans is asymmetric; the highest pressure and the most significant cholinergic contribution occurs toward the left. The basis of this asymmetry was examined using the cat as a model. METHODS: The LES pressure profile was determined using a manometry catheter with four ports oriented at right angles. The LES was dissected into right and left halves with the latter including a contribution from the oblique gastric sling fibers. Isometric tension responses were studied in vitro. RESULTS: In vivo, both the initial LES pressure (31.8 +/- 4.0 mm Hg) and the decrease (79.9% +/- 6.4%) after intravenous atropine (100 micrograms/kg) were greatest in the leftward direction. In vitro, both halves of the LES developed similar spontaneous tension, but the increase in tension to carbachol was twofold greater on the left than the right. Eserine increased and atropine decreased initial tension by 25%-30% in both. Strips from either side relaxed in response to electrical stimulation but the response was more complete in strips from the right, whereas sodium nitroprusside produced similar relaxation in both. CONCLUSIONS: Regional differences in the LES pressure and its cholinergic component can be accounted for by differences in the in vitro properties of the LES muscle fiber groups.
Animals↗
Protein tyrosine phosphorylation in normal rat tissues.
1. Exogenous and endogenous tyrosine protein phosphorylation activities were examined in soluble and particulate fractions from various normal tissues by using poly-[Glu-80Na, Tyr20] and a monoclonal antibody specific for phosphotyrosine. 2. Phosphorylation of the exogenous substrate by the particulate forms of TPKs was 2- to 10-fold higher than by soluble forms. The activities of particulate and soluble enzymes decreased in the following order: spleen > (thymus = kidney) > testes > or = (pancreas = liver = brain) > heart. 3. The level of endogenous phosphorylation in the tissues decreased respectively in the following order: thymus > brain > or = (pancreas = liver) > spleen > testes > kidney > heart for the particulate fractions, and spleen > thymus > brain > pancreas > or = liver > testes > kidney > heart for the soluble fractions. 4. A large number of phosphotyrosine-containing proteins were detected. In addition, several phosphotyrosine-containing proteins of similar molecular weight were found in different tissues and fractions.
Amino Acid Sequence↗
In vivo measurement of feline esophageal tone.
Using an isotonic recording device (barostat), we assessed feline esophageal smooth and striated muscle tone in vivo and determined the effects of a cholinergic agonist (bethanechol) and antagonist (atropine) and the effect of body position on this tone. Studies were performed on six cats under light intravenous ketamine anesthesia. Two parameters were analyzed: compliance and resistance to initial stretch (resting tone). Smooth muscle compliance (0.51 +/- 0.03 ml/mmHg) was significantly greater than that of the striated muscle section (0.26 +/- 0.02 ml/mmHg; P = 0.0260). Resting tone was low in both esophageal sections. Neither atropine nor bethanechol had any significant effect on the two tone parameters measured in smooth muscle. Change in body position had no influence on the intraesophageal balloon volume. We conclude that esophageal wall compliance varies according to location (smooth vs. striated muscle) and that esophageal smooth muscle tone is not under cholinergic excitatory control. Isotonic recording in vivo should allow further investigations of the nature of the neural and myogenic control of esophageal tone and of the relationships between phasic and tonic activity.
Animals↗
Tyrosine protein phosphorylation in plasma membranes of rat kidney cortex.
The endogenous tyrosine protein kinase activity (TPKA) associated with brush-border (BBM) and basolateral (BLM) membranes of rat kidney cortex was studied with an anti-phosphotyrosine monoclonal antibody (PY20). Distinct major phosphotyrosine-containing proteins were associated with BBM (50, 54, and 120 kDa) and BLM (37, 90, 130, and 170 kDa). For both plasma membranes, tyrosine phosphorylation leveled off after 10 min of incubation. Endogenous phosphotyrosine-specific protein phosphatases (PT-Pases) were active in both membranes, since the presence of sodium vanadate or ammonium molybdate, which are inhibitors of PTPases, was essential to detect endogenous phosphorylation. Substrates and/or tyrosine protein kinases (TPKs) seem to be differently distributed in these plasma membranes, since phosphorylation of endogenous substrates in BLM and BBM was differently sensitive to competitive inhibitors of TPKs. Moreover, insulin- and insulin-like growth factor I-stimulated tyrosine phosphorylation of a 90-kDa substrate was only observed in solubilized BLM proteins. However, similar p60v-src-related TPKs appear to be present in the BBM and BLM, since an antibody raised against p60v-src recognized proteins of 52, 58, and 75 kDa by immunoblotting and could immunoprecipitate the TPKs associated with both plasma membranes. These data provide evidence that the endogenous tyrosine protein phosphorylation observed in the BLM is catalyzed by nonreceptor TPKs as well as receptor TPKs, whereas that observed in the BBM is exclusively due to nonreceptor TPKs.
Adenosine Triphosphate↗
Distinct presynaptic control of dopamine release in striosomal- and matrix-enriched areas of the rat striatum by selective agonists of NK1, NK2 and NK3 tachykinin receptors.
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Animals↗
The central vagal efferent supply to the esophagus and lower esophageal sphincter of the cat.
BACKGROUND: Little is known of the central efferent neurons innervating the smooth muscle esophagus. The aim of this study was to define the location of the efferent neural pathways of the brain stem swallowing mechanism in the cat, particularly those supplying the esophageal body smooth muscle. METHODS: Fluorescent, retrogradely transported tracers were injected into the cervical striated muscle and thoracic smooth muscle segments of the esophagus and also the lower esophageal sphincter. RESULTS: Striated muscle efferents were found in the rostral nucleus ambiguus, but approximately 8% were located in the dorsal motor vagal nucleus. Smooth muscle efferents were present in the dorsal motor vagal nucleus in two groups, one rostral and one caudal to the obex. An additional group was found in nucleus retroambiguus. Approximately 8% of the total smooth muscle efferents were present in rostral nucleus ambiguus and were lateral to the striated muscle efferents. The lower esophageal sphincter efferents had a similar distribution to the smooth muscle efferents, but the rostral concentration of cells in the dorsal motor vagal nucleus was shifted caudally. CONCLUSIONS: Esophageal body smooth muscle motoneurons are arranged with a similar distribution to those innervating the lower esophageal sphincter but with some topographic variation.
Afferent Pathways↗
Production of a cloned xylanase in Bacillus cereus and its performance in kraft pulp prebleaching.
Xylanase production from a Bacillus subtilis gene cloned into a strain of Escherichia coli was monitored. Although this gene was expressed in E. coli at several temperatures, efficient xylanase secretion did not occur; the observed protein release apparently depended on cell leakage or lysis. Screening for a better microbial protein secretor free of cellulase selected Bacillus cereus No. 518. A bidirectional vector plasmid (pMK3) was employed to carry the cloned gene into this B. cereus strain. Transformation was carried out by electroporation. Total xylanase production by the new pMK3-borne gene in B. cereus was similar to that from E. coli but the xylanase was shown to be normally secreted. The xylanase gene products from the E. coli and B. cereus hosts were shown to function identically. Both xylanases improved the delignification of unbleached softwood and hardwood kraft pulps, thus reducing the Cl2 required to achieve a given degree of bleaching, without altering the physical properties of the fibers. Using a target kappa number (lignin content) of 5, xylanase pretreatment of aspen kraft (chemical) pulp led to a 22% savings of chlorine. Adsorbable organic halogens in the bleachery effluent were also lowered by more than 50%.
Bacillus cereus↗
The role of the medial pallidum in the pathophysiology of akinesia in primates.
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Animals↗
Distinct presynaptic control of dopamine release in striosomal- and matrix-enriched areas of the rat striatum by selective agonists of NK1, NK2, and NK3 tachykinin receptors.
Using a sensitive in vitro microperfusion method, the effects of selective and potent agonists of NK1, NK2, and NK3 tachykinin receptors ([Pro9]SP, ([Lys5,MeLeu9,Nle10]NKA-(4-10), and [Pro7]NKB, respectively) on the presynaptic control of dopamine release were investigated in striosomal-enriched (area rich in [3H]naloxone binding sites) and matrix-enriched areas of the rat striatum. Marked differences could be demonstrated as follows: (i) when used at 0.1 microM, the NK1 agonist stimulated the release of [3H]dopamine continuously synthesized from [3H]tyrosine in both compartments, while the NK2 and NK3 agonists enhanced the release of [3H]dopamine only in the matrix; (ii) the stimulatory effect of the NK3 agonist was less pronounced than those of the NK1 and NK2 agonists; (iii) the NK1 agonist-evoked responses were tetrodotoxin (1 microM) sensitive, while those of the NK2 and NK3 agonists were, respectively, partially and totally tetrodotoxin resistant; (iv) specific receptors are involved in these responses since the stimulatory effects of the NK1 and NK2 agonists were, respectively, blocked by potent antagonists of NK1 (RP-67580; 1 microM) and NK2 (SR-48968; 1 microM) receptors, while these antagonists did not affect the NK3 agonist-evoked response; (v) the indirect stimulatory effect of the NK1 agonist was partially reduced under local blockade of cholinergic transmission in the matrix but not in the striosomal-enriched area. Interestingly, this study also revealed mismatches between autoradiographic data and receptor-mediated responses, since NK2 binding sites could not be observed in the striatum while NK3 but not NK1 binding sites were visualized in the striosomal-enriched area.
Animals↗
Tyrosine protein kinase activity in renal brush-border membranes.
Tyrosine protein kinase (TPK) activity was detected in rat renal brush-border membranes (BBM) using poly(Glu80Na,Tyr20) as a substrate. Maximal TPK activity required prior detergent dispersion of the membranes with 0.05% Triton X-100 and the presence of vanadate, a potent inhibitor of phosphotyrosine protein phosphatases, in the phosphorylation medium. Optimal conditions for measurement of TPK activity were 10 mM of MgCl2 and MnCl2, at 30 degrees C and pH 7.0. TPK activity was inhibited by genistein, with a IC50 value of 15 microM, while no inhibition was observed in the presence of 1-(5-isoquinolinesulfonyl)-2-methyl-piperazine dihydrochloride (H7), an inhibitor of serine-threonine kinases. TPK activity was enriched 4-fold in the BBM fraction relative to cortex homogenate. It was co-enriched with BBM enzyme markers, but not with those of the basolateral membrane (BLM). The endogenous substrates of TPK in brush-border and basolateral membranes were determined by Western blot analysis using an antiphosphotyrosine monoclonal antibody (PY20). Various phosphotyrosine-containing proteins were found in the BBM (31, 34, 46, 50, 53, 72, 90, 118 and 170 kDa) and in the BLM (37, 48, 50, 53, 72, 90, 130 and 170 kDa). Addition of exogenous insulin receptor to BBM and BLM increased the phosphorylation of most of the substrates. Solubilization of the TPK activity from BBM with 0.5% CHAPS and subsequent gel filtration on Superdex 75 yielded two peaks of tyrosine protein kinase activity with apparent molecular masses of 49 and 66 kDa. These results provide evidence for a non-receptor TPK activity associated with the renal tubular luminal membrane.
Animals↗
The distribution of spinal and vagal sensory neurons that innervate the esophagus of the cat.
The distribution of spinal and vagal neurons that convey sensory information from the distal smooth muscle esophagus is poorly documented. Therefore, sensory cell bodies were retrogradely labeled by injecting fast blue into the striated and smooth muscle of the esophageal body and into the lower esophageal sphincter of the cat. The maximum distribution of spinal sensory neuron labeling was found in the following dorsal root ganglia: C1-T8 (striated muscle); C5-L2 (smooth muscle), and T1-L3 (lower esophageal sphincter). Vagal sensory neurons in the nodose ganglion were found to have a crude topographic layout. The total number of vagal sensory neurons labeled by injection into the three esophageal areas was greater than the number of spinal neurons labeled (809.7 +/- 166.1 vs. 328.9 +/- 53.4; mean +/- SEM; n = 12; P less than 0.005). It is concluded that spinal sensory neurons of the esophagus are segmentally arranged. Accordingly, each level of the esophagus has a distinct but overlapping sensory projection to the spinal cord, and afferents from all parts of the esophagus overlap the known spinal distribution of cardiac afferents.
Animals↗
Alloimmunization to platelet antigen HPA-1a (PIA1) is strongly associated with both HLA-DRB3*0101 and HLA-DQB1*0201.
Antibodies to the platelet HPA-1a antigen can elicit in the newborn a condition known as neonatal alloimmune thrombocytopenic purpura (NAITP). Previous studies based on RFLP analysis showed that 100% of HPA-1a-negative women who produced anti-HPA-1a antibodies (responders) were HLA-DRw52a (DRB3*0101). However, this specificity could also be found in some HPA-1a-negative women not producing anti-HPA-1a antibodies (nonresponders). We have analyzed in detail by PCR-SSOP the HLA-DR, -DQ, and -DP loci of 36 responders and 10 nonresponders. We found that while the allele DRB3*0101 was present in the vast majority of responders (91%), there were exceptions. Furthermore, the DQB1*0201 allele was found to be present in almost all responders (94%), but again was also found in nonresponders. The risk of alloimmunization to HPA-1a in an HPA-1b homozygous mother significantly increases with the presence of either allele, the odds ratio being 39.7 for DQB1*0201 and 24.9 for DRB3*0101. Sequencing of exon 2 of these two alleles from responders indicated no sequence difference when compared with the consensus sequences. This indicates that they do not represent variants when compared with the same alleles found in some nonresponders.
Alleles↗