Biomedical subjects

E Rousseau

Publications and source records attributed to E Rousseau.

At least 73 records · Page 4Linked to original sources

PubMed1991

[Continuing medical education in pediatrics: maintaining of professional competence with different interactive models].

The forming of professional competence constitutes the primary mission of the university. It follows that the maintenance of professional competence is part of that same mission. Physicians will always remain the first motor of their own competence, but the university will play a major role in organizing and providing continuing medical education activities. At the University of Montreal, many CME programs are regularly offered to practising physicians concerned by pediatric patients (400 pediatricians and 7,000 family physicians). These programs include the following collective activities: 1), biannual convention on pediatric updates; 2), one-day meeting on selected topics; 3), advanced pediatric life support courses; 4), regional conference touring programs by university staff. We have also developed the following individual CME activities: 1), CME letter; 2), self-evaluation questionnaires; 3), miniresidency programs; 4), CME TV series; 5), problem-solving slide series. All these activities are planned according to a need assessment basis and an on-going evaluation process. Priority is given to interactive methods of student-teacher relationship.

Education, Medical, Continuing↗

PubMed1991

Television and the 3- to 10-year-old child.

A questionnaire on the use of television was administered to the parents of 387 children aged between 3 and 10 years. All families owned at least one television set and 57.6% of families owned two or more sets, with one in the child's bedroom in 10.6% of cases. Television was turned on all day in 16% of cases, mostly in families with low level of parental education (P less than .01). Television was on at mealtime in 54.5% of cases; 45.2% of children were watching television for between 7 to 16 hours per week, and the heavy viewers belonged to families with low levels of maternal education (P less than .05). About one third of children watched television without any interdiction set by their parents. According to age, from 28% to 40% of children watched violence on television. Parents believed that television facilitates learning (65.3%) but were concerned about violence (22.7%) and commercials (7.4%). Finally, 63.3% of parents reported that they would like to obtain more information about television use. According to this survey, many children are watching television without any limits being set by their parents and are witnessing violent scenes at an impressionable and vulnerable age. The pediatrician should include at routine office visits parental guidance on the mediation of television effects through coviewing, content discussion with children, and program selection.

Analysis of Variance↗

PubMed1990

pH modulates conducting and gating behaviour of single calcium release channels.

Intracellular pH changes affect excitation-contraction coupling in skeletal and cardiac muscles. However the proton implication in modulating the sarcoplasmic reticulum Ca2+ release channel activity has never been visualized at single channel level. A large conducting Ca2+ release pathway has previously been characterized after incorporation of skeletal and cardiac sarcoplasmic reticulum vesicles into planar lipid bilayers. This channel has been activated by micromolar and millimolar concentrations of Ca2+ and ATP, respectively. The pH was independently varied on each side of the channels. Acidification of the cis-chamber (7.4 to 6.6) induced a modification of the gating behaviour, resulting in a decrease of the open probability. This effect was completely reversible. On the other hand, acidification of the trans-chamber (7.4 to 6.8) induced a reduction of the unitary conductance of the sarcoplasmic reticulum Ca2+ release channel.

Animals↗

PubMed1990

Surgical complications of the hemolytic-uremic syndrome.

Hemolytic-uremic syndrome (HUS) of childhood is a triad of acute hemolytic anemia, thrombocytopenia, and acute renal failure associated with a gastrointestinal prodrome. From 1977 to 1988, 134 patients with HUS were admitted to this institution. All patients presented with abdominal pain and diarrhea, which was virtually always bloody. Seventy-eight patients (60%) required dialysis. Five patients died (4%). One patient died as a result of colon perforation, the other four patients died of other nonsurgical complications of HUS. Three patients underwent exploratory laparotomy. One patient had a hemoperitoneum from mesenteric and transmural bleeding of the entire intraabdominal colon. Another patient had undergone surgery elsewhere for presumed intussusception with pancolitis found at exploration. Fourteen days postoperatively, he had a spontaneous perforation of the transverse colon. The third patient presented with pancolitis and perforation of the transverse colon. Despite surgical intervention he died on the sixth postoperative day. One other patient was treated conservatively for pancreatitis, which developed 3 weeks after her presentation with HUS. Complications requiring surgical intervention in HUS are rare, potentially lethal, and usually involve the colon.

Child, Preschool↗

PubMed1990

Decreased necessity for dialysis with loop diuretic therapy in hemolytic uremic syndrome.

High dose loop diuretic therapy was administered at time of admission to hospital or at time of diagnosis to 54 patients with childhood hemolytic uremic syndrome. Forty-one patients maintained a diuresis sufficient to avoid the necessity for dialysis. When compared to an earlier time period the dialysis rate fell from 82% to 24% with furosemide therapy. Though a change in disease severity may explain the decrease in necessity for dialysis, a salutary effect of furosemide therapy may also be responsible.

Blood Urea Nitrogen↗

PubMed1990

AIDS and the urinary tract.

A wide spectrum of renal diseases ranging from glomerulopathic lesions to tumors may be associated with HIV infection. This infection may also complicate the course of dialysis and renal transplantation. We review the renal complications of HIV infection.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Structural and functional correlation of the trypsin-digested Ca2+ release channel of skeletal muscle sarcoplasmic reticulum.

The effect of trypsin digestion on the (i) fragmentation pattern, (ii) activity, (iii) [3H]ryanodine binding, and (iv) sedimentation behavior of the skeletal sarcoplasmic reticulum (SR) ryanodine receptor-Ca2+ release channel complex has been examined. Mild tryptic digestion of heavy, junctional-derived SR vesicles resulted in the rapid disappearance of the high molecular weight (Mr approximately 400,000) Ca2+ release channel protein on sodium dodecyl sulfate gels and appearance of bands of lower Mr upon immunoblot analysis, without an appreciable effect on [3H]ryanodine binding or the apparent S value (30 S) of the 3-[3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps)-solubilized channel complex. Further degradation to bands of Mr greater than 70,000 on immunoblots correlated with a reduction of channel size from 30 S to 10-15 S and loss of high affinity [3H]ryanodine binding to the trypsinized receptor, while low affinity [3H]ryanodine binding and [3H]ryanodine bound prior to digestion were retained. Parallel 45Ca2+ efflux measurements also indicated retention of the Ca2+, Mg2+, and ATP regulatory sites, although Ca2+-induced 45Ca2+ release rates were changed. In planar lipid bilayer-single channel measurements, addition of trypsin to the cytoplasmic side of the high conductance (100 pS in 50 mM Ca2+), Ca2+-activated SR Ca2+ channel initially increased the fraction of channel open time and was followed by a complete and irreversible loss of channel activity. Trypsin did not change the unitary conductance, and was without effect on single channel activity when added to the lumenal side of the channel.

Adenosine Monophosphate↗

PubMed1989

Structural and functional characterization of the purified cardiac ryanodine receptor-Ca2+ release channel complex.

Using density gradient centrifugation and [3H]ryanodine as a specific marker, the ryanodine receptor-Ca2+ release channel complex from Chaps-solubilized canine cardiac sarcoplasmic reticulum (SR) has been purified in the form of an approximately 30 S complex, comprised of Mr approximately 400,000 polypeptides. Purification resulted in a specific activity of approximately 450 pmol bound ryanodine/mg of protein, a 60-70% recovery of ryanodine binding activity, and retention of the high affinity ryanodine binding site (KD = 3 nM). Negative stain electron microscopy revealed a 4-fold symmetric, four-leaf clover structure, which could fill a box approximately 30 x 30 nm and was thus morphologically similar to the SR-transverse-tubule, junctionally associated foot structure. The structural, sedimentation, and ryanodine binding data strongly suggest there is one high affinity ryanodine binding site/30 S complex, comprised of four Mr approximately 400,000 subunits. Upon reconstitution into planar lipid bilayers, the purified complex exhibited a Ca2+ conductance (70 pS in 50 mM Ca2+) similar to that of the native cardiac Ca2+ release channel (75 pS). The reconstituted complex was also found to conduct Na+ (550 pS in 500 mM Na+) and often to display complex Na+ subconducting states. The purified channel could be activated by micromolar Ca2+ or millimolar ATP, inhibited by millimolar Mg2+ or micromolar ruthenium red, and modified to a long-lived open subconducting state by ryanodine. The sedimentation, subunit composition, morphological, and ryanodine binding characteristics of the purified cardiac ryanodine receptor-Ca2+ release channel complex were similar to those previously described for the purified ryanodine receptor-Ca2+ release channel complex from fast-twitch skeletal muscle.

Animals↗

PubMed1989

Single chloride-selective channel from cardiac sarcoplasmic reticulum studied in planar lipid bilayers.

The behavior of single Cl- channel was studied by fusing isolated canine cardiac sarcoplasmic reticulum (SR) vesicles into planar lipid bilayers. The channel exhibited unitary conductance of 55 pS (in 260 mM Cl-) and steady-state activation. Subconductance states were observed. Open probability was dependent on holding potentials (-60 to +60 mV) and displayed a bell-shaped relationship, with probability values ranging from 0.2 to 0.8 with a maximum at -10 mV. Channel activity was irreversibly inhibited by DIDS, a stilbene derivative. Time analysis revealed the presence of one time constant for the full open state and three time constants for the closed states. The open and the longer closed time constants were found to be voltage dependent. The behavior of the channel was not affected by changing Ca2+ and Mg2+ concentrations in both chambers, nor by adding millimolar adenosine triphosphate, or by changing the pH from 7.4 to 6.8. The presence of sulfate anions decreased the unit current amplitude, but did not affect the open probability. These results reveal that at the unitary level the cardiac SR anion-selective channel has distinctive as well as similar electrical properties characteristic of other types of Cl- channels.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1989

Multiple conductance states of the purified calcium release channel complex from skeletal sarcoplasmic reticulum.

The CHAPS-solubilized and purified 30S ryanodine receptor protein complex from skeletal sarcoplasmic reticulum (SR) was incorporated into planar lipid bilayers. The resulting electrical activity displayed similar responses to agents such as Ca2+, ATP, ryanodine, or caffeine as the native Ca2+ release channel, confirming the identification of the 30S complex as the Ca2+ release channel. The purified channel was permeable to monovalent ions such as Na+, with the permeability ratio PCa/PNa approximately 5, and was highly selective for cations over anions. The purified channel also showed at least four distinct conductance levels for both Na+ and Ca2+ conducting ions, with the major subconducting level in NaCl buffers possessing half the conductance value of the main conductance state. These levels may be produced by intrinsic subconductances present within the channel oligomer. Several of these conductances may be cooperatively coupled to produce the characteristic 100 +/- 10 pS unitary Ca2+ conductance of the native channel.

Animals↗

PubMed1989

Hospital practices and breastfeeding duration: a meta-analysis of controlled trials.

Controlled clinical trials studying the influence of hospital practices on breastfeeding duration were combined using meta-analysis. Nine studies were selected. Supplementation demonstrated a negative clinical effect on breastfeeding duration that was not significant. Nursing support demonstrated a positive clinical effect on breastfeeding duration that was not statistically significant if there was no telephone follow-up, but was significant if there was telephone follow-up. Early contact revealed a positive clinical effect that was significant. We conclude that early contact and nursing support with telephone follow-up appear as enhancing factors of breastfeeding duration.

Aftercare↗

PubMed1989

Respiratory failure and mechanical ventilation in severe bronchiolitis.

A retrospective review of children who needed mechanical ventilation for severe bronchiolitis identified 62 cases over a 10 year period. The mean age at initiation of ventilation was 73 days (range: 14-201). Compared with a group of 150 children in hospital for bronchiolitis but not transferred to the intensive care unit, these 62 cases were significantly younger (73.0 compared with 166.3 days), and smaller (4.5 compared with 6.8 kg), and significantly more had been born prematurely (40% compared with 16%). Taken independently, age, weight, and prematurity were significantly associated with the need for artificial ventilation, weight being the most important factor. Using stepwise logistic regression, prematurity in itself added to the quality of the prediction but age did not. The mean duration of mechanical ventilation was 105 hours (range 2-381). Duration of ventilation was significantly longer in children with a low gestational age at birth and a positive familial history of atopy. There were no deaths, and no patient developed pneumothorax or pneumomediastinum. Mechanical ventilation is well tolerated and safe in acute bronchiolitis.

Age Factors↗

PubMed1989

Single cardiac sarcoplasmic reticulum Ca2+-release channel: activation by caffeine.

Caffeine is thought to affect excitation-contraction coupling in cardiac muscle by activating the sarcoplasmic reticulum (SR) Ca2+-release channel. The effect of caffeine at the single channel level was studied by incorporating canine cardiac SR vesicles into planar lipid bilayers. Cardiac Ca2+-release channels were activated in a steady-state manner by millimolar cis-caffeine and displayed a unitary conductance (77 pS in 50 mM Ca2+ trans) similar to that previously observed for the Ca2+-activated cardiac channel. The caffeine-activated channel was moderately sensitive to the voltage applied across the bilayer, was sensitive to further activation by ATP, and was inhibited by Mg2+ and ruthenium red. Kinetic analysis showed that at low Ca2+ concentration, caffeine activated the channel by increasing the frequency and the duration of open events.

Animals↗

PubMed1989

Calmodulin modulation of single sarcoplasmic reticulum Ca2+-release channels from cardiac and skeletal muscle.

Sarcoplasmic reticulum (SR) contains a Ca2+-conducting channel that is believed to play a central role in excitation-contraction coupling by releasing the Ca2+ necessary for muscle contraction. The effects of calmodulin on single cardiac and skeletal muscle SR Ca2+-release channels were studied using the planar lipid bilayer-vesicle fusion technique. Calmodulin inhibited Ca2+-release channel opening by reducing the mean duration of single-channel open events without having an effect on single-channel conductance. Inhibition by calmodulin was dependent on Ca2+ concentration and occurred in the absence of ATP. The effects of calmodulin were reversed by mastoparan, a calmodulin-binding peptide. Two other calmodulin antagonists [calmidazolium and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide] modified the gating behavior of the channel in the absence of exogenous calmodulin in a concentration- and Ca2+-dependent manner. Our results suggest that calmodulin can modulate excitation-contraction coupling by directly interacting with the SR Ca2+-release channel of cardiac and skeletal muscle.

Animals↗

PubMed1989

Hemolytic uremic syndrome: glomerular filtration rate, 6 to 11 years later measured by 99mTc DTPA plasma slope clearance.

Thirty-seven patients who had been discharged from hospital six to eleven years after an acute episode of hemolytic uremic syndrome were studied. Glomerular filtration rates were measured by plasma slope clearance using 99mTc DTPA. Eleven patients had GFRs below 60 ml/min/1.73 m2. Hemolytic uremic syndrome may result in an appreciable deterioration in GFR undectable by routine laboratory tests and without clinical signs.

Acute Disease↗

PubMed1989

[Hospital practices and duration of breast feeding: meta-analysis].

Clinical trials studying the influence of hospital practices on breast-feeding duration were combined in a meta-analysis. Nine studies were selected. The global quality score was poor, and varied between 11.6 and 71.5 (Chalmers' scale). The results of each study were pooled using Peto's method and showed the following findings. Supplementation demonstrated a negative clinical effect on breast-feeding duration which was not significant (OR: 0.77, 95% CI[0.59, 1.02] p greater than 0.05). Nursing support demonstrated a positive clinical effect on breast-feeding duration which was not statistically significant if there was no telephone follow-up (OR : 2.29, 95% CI [0.87, 6.02] p greater than 0.05), but was significant if there was telephone follow-up (OR : 2.01, 95% CI [1.37, 2.94] p less than 0.05). Early contact revealed a positive clinical effect which was significant (OR : 2.96, 95% CI [1.6, 5.22] p less than 0.05). In conclusion, early contact and nursing support with telephone follow-up appear as enhancing factors of breast-feeding duration.

Adult↗

PubMed1988

Activation of the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum by caffeine and related compounds.

The caffeine-sensitive Ca2+ release pathway in skeletal muscle was identified and characterized by studying the release of 45Ca2+ from heavy sarcoplasmic reticulum (SR) vesicles and by incorporating the vesicles or the purified Ca2+ release channel protein complex into planar lipid bilayers. First-order rate constants for 45Ca2+ efflux of 1 s-1 were obtained in the presence of 1-10 microM free Ca2+ or 2 X 10(-9) M free Ca2+ plus 20 mM caffeine. Caffeine- and Ca2+-induced 45Ca2+ release were potentiated by ATP and Mg.ATP, and were both inhibited by Mg2+. Dimethylxanthines were similarly (3,9-dimethylxanthine) or more (1,7-, 1,3-, and 3,7-dimethylxanthine) effective than caffeine in increasing the 45Ca2+ efflux rate. 1,9-Dimethylxanthine and 1,3-dimethyluracil (which lacks the imidazole ring) did not appreciably stimulate 45Ca2+ efflux. Recordings of calcium ion currents through single channels showed that the Ca2+- and ATP-gated SR Ca2+ release channel is activated by addition of caffeine to the cis (cytoplasmic) and not the trans (lumenal) side of the channel in the bilayer. The single channel measurements further revealed that caffeine activated Ca2+ release by increasing the number and duration of open channel events without a change of unit conductance (107 pS in 50 mM Ca2+ trans). These results suggest that caffeine exerts its Ca2+ releasing effects in muscle by activating the high-conductance, ligand-gated Ca2+ release channel of sarcoplasmic reticulum.

Action Potentials↗

PubMed1988

[Prevalence of Aeromonas spp. pediatric gastroenteritis].

A selective medium and biochemical tests were used to search for Aeromonas spp. in the stools of 536 children, more than 90% of whom had "gastroenteritis", seen at Sainte-Justine Hospital, Montreal, in June or July 1986. The organism was found in seven children, six of whom had bloody diarrhea. One of the six, a 6 1/2-year-old boy, required intravenous alimentation and later manifested ulcerative colitis; the other five recovered. The remaining child, a 14-year-old boy, had synovitis of the knee and spondylarthritis. Two of the seven carried other enteric pathogens. The authors discuss the pathogenicity of Aeromonas spp., which is not very marked in temperate climates, in human summer diarrhea and its possible role in the development of ulcerative colitis.

Adolescent↗