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Biomedical subjects

M Valois

Publications and source records attributed to M Valois.

At least 19 recordsLinked to original sources
PubMed1997

Effectiveness of salt versus glass bead sterilizers.

Microorganisms can be removed from dental instruments by various methods, including treatment in salt and glass bead sterilizers. However, no rigorous, controlled, in vivo or in vitro studies have been performed to verify the respective efficiencies of these methods. The goals of this study were to determine if the positioning of instruments at the centre or edge of a salt sterilizer results in differential sterilization effectiveness, and to compare the effectiveness of salt sterilizers relative to glass bead sterilizers. Autoclaved number 60 reamers were contaminated by plunging them to the handle in a commercial Bacillus stearothermophilus spore suspension. They were then sterilized for different periods of time and at different positions in the sterilizers. Each experiment included positive and negative controls. The results showed that better sterilization is achieved at the edge of the chamber than at the centre, and that salt sterilizers are more effective than glass bead sterilizers for a given period of time (15 seconds) in the sterilizer.

Culture Media↗
PubMed1994

The reliability of the Periotron 6000 in the presence of plaque.

The aim of this study was to evaluate if the presence of supragingival plaque can influence measurements of gingival crevicular fluid flow (CFF) taken with the Periotron 6000 unit. Sixty-seven experimental sites and 67 contralateral control sites were randomly chosen. Crevicular fluid was collected on a filter paper strip for 15 seconds and the CFF was measured using the Periotron 6000 unit: CFF1. The supragingival plaque was removed from the experimental site with a Gracey curette and the plaque index (PI) was estimated. Five minutes later, a second CFF measurement was taken: CFF2. On the control tooth, the plaque was not removed, and the PI was established after the second CFF measurement. There was no significant difference between the CFF1 and the CFF2 values for the control teeth. In the experimental teeth, a PI of 3.0 increased the CFF1 (pre-plaque removal) compared to the CFF2 (post-plaque removal) value by 20.6 Periotron units (PU) (p = 0.0004). A PI of 2.0 caused a 7.3 PU increase (p = 0.0370). There were no significant changes for a PI of 1.0 or 0. In this type of experimental protocol, the results also indicated that CFF differences were not affected by the gingival index (GI) for either the experimental or control groups. These results indicate that large amounts of supragingival plaque can significantly elevate CFF measurements, as determined by the Periotron 6000 unit.

Adolescent↗
PubMed1989

Recent advances in understanding the mechanisms of drug-induced torsades de pointes arrhythmias.

QTU prolongation and polymorphic ventricular tachycardia "torsades de pointes" have occurred in association with electrolyte abnormalities and during therapy with class IA and III antiarrhythmic drugs. Several recent studies have suggested that the arrhythmia may be due to bradycardia-dependent early afterdepolarizations and triggered activity. These drugs produce 2 types of triggered activity, each with a different frequency profile. The possible role of each type in arrhythmia generation is discussed. The existing evidence suggest that drug-induced triggered activity may originate in the Purkinje system. Triggered activity can be abolished or prevented by various interventions that are also effective clinically. The results of studies at the cellular level, when compared with recordings of monophasic action potentials in vivo, suggest a role for early afterdepolarizations in torsades de pointes arrhythmias.

Anti-Arrhythmia Agents↗
PubMed1989

["Treat" or "not treat"?].

During the last few years, we have had to face the sad reality and statistics related to hepatitis B and AIDS. These two infectious entities are in fact the major cause of concern for dentists in their capacity as health professionals. This article reviews certain legislative points of view which should help every dentist in their decision as to whether to treat these so-called "infectious" or "contagious" patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Disinfectants and sterilizants for dental instruments].

A comparative study of ten (10) products recommended for disinfection and/or sterilization of dental instruments is detailed. Four (4) out of fourteen (14) characteristics have been evaluated, namely corrosive power, monthly cost, odor and availability.

Corrosion↗
PubMed1989

[Hepatitis B: what you always wanted to know].

More than two million individuals die each year as a result of infection from the hepatitis B virus, either directly from fulgurant hepatitis, or in the majority of cases, from the long term after-effects. The high risk groups, the reasons for cross contamination, the various ways of transmitting the disease, the rate which individuals are being vaccinated against hepatitis B, the vaccines and the recommendations for controlling transmission are some of the subjects related to in the article. The dentist and the dental team must function with a viable asepsis protocol.

Dentists↗
PubMed1989

["Infection control of laboratory items" a myth?].

Impression materials and impression trays must be cleaned and disinfected before being used and adjusted in the mouth, or sent to the laboratory. This article reviews some of the practical recommendations for dental offices and laboratories.

Communicable Disease Control↗
PubMed1987

Modification of the frequency- and voltage-dependent effects of quinidine when administered in combination with tocainide in canine Purkinje fibers.

Frequency- and voltage-dependent modification of drug-induced inhibition of maximal upstroke velocity of the action potential (Vmax) by the combined administration of two class I antiarrhythmic drugs was studied in canine Purkinje fibers, taking depression of upstroke velocity as an indicator of sodium channel blockade. The kinetics of onset of drug-induced Vmax depression and the time course of Vmax recovery were studied after exposure to therapeutic concentrations of tocainide (50 microM) and quinidine (5 microM) both singly and in combination. The rate constant for onset of block during a drive train at a cycle length of 600 msec was 0.95 +/- 0.32 pulses in the presence of tocainide and 5.61 +/- 0.50 pulses in the presence of quinidine. The magnitude of block was three times greater with quinidine than with tocainide. The magnitude of block produced by the combination was no greater than that produced by quinidine alone and may be partly due to abbreviation of action potential duration by tocainide. Onset of block in the presence of the combination was best fitted by a double exponential with rate constants of 0.88 +/- 0.19 and 6.47 +/- 1.36 pulses. Vmax recovery after termination of a rapid train of impulses was delayed by both drugs. Poststimulation recovery from either tocainide- or quinidine-induced block was characterized by a single time constant (1.04 +/- 0.49 and 4.81 +/- 0.76 sec, respectively), while that of the combination was characterized by two time constants (0.43 +/- 0.22 and 5.94 +/- 0.56 sec), presumably corresponding to dissociation of each drug from the sodium channel receptor. The mixture of the two drugs produced a large depression of Vmax of early diastolic premature responses without producing much further depression of Vmax than that produced by quinidine alone at longer coupling intervals. The time constant of recovery from tocainide-induced block was greatly dependent upon membrane potential. After steady-state changes in frequency, the combination produced a greater depression of Vmax at rapid heart rates compared with that produced by quinidine alone, but abbreviated action potential duration more at slower heart rates. Addition of tocainide to fibers equilibrated with quinidine shifted the Vmax-membrane potential relationship to more hyperpolarized potentials, resulting in greater depression of Vmax at more depolarized membrane potentials with little or no additional depression of Vmax at more negative membrane potentials. The results provide a rationale for a possible enhanced antiarrhythmic efficacy of a combination of two class I drugs that have different kinetics of interaction with the sodium channel.

Action Potentials↗
PubMed1986

Experimental amitriptyline intoxication: treatment of cardiac toxicity with sodium bicarbonate.

Overdose with amitriptyline and other tricyclic antidepressants can result in ventricular conduction abnormalities as well as severe ventricular arrhythmias. The arrhythmogenic effects of these compounds may be attributed to their direct local anesthetic actions in blocking sodium channels in cardiac membranes. Thus tricyclic-induced ventricular arrhythmias usually do not respond well to therapy with standard Class I antiarrhythmic drugs that also have the same direct local anesthetic action and may potentiate the adverse effects of tricyclic antidepressants. Cardiac toxicity was produced in dogs by the administration of amitriptyline, both orally and IV. At serum concentrations less than 2,000 ng/mL, sinus tachycardia occurred with widened QRS complexes. At higher concentrations, QRS duration became more markedly prolonged and was followed by ventricular tachyarrhythmias. Occurrence of ventricular tachyarrhythmias was associated with QRS durations of more than 0.11 second. Sodium bicarbonate (18 to 36 mEq) administered IV over either 30 seconds or two minutes rapidly converted ventricular tachycardia to normal sinus rhythm. Conversion was associated with abbreviation of the QRS complex and was accompanied by a rise in both systolic and diastolic pressures. The duration of sodium bicarbonate effect paralleled the duration of the changes in arterial pH and plasma bicarbonate concentrations. In vitro studies in cardiac Purkinje fibers suggested that reversal of amitriptyline-induced cardiac membrane effects by sodium bicarbonate may be attributed not only to alkalinization but also to increased in extracellular sodium concentration, diminishing the local anesthetic action of amitriptyline and resulting in less sodium channel block.(ABSTRACT TRUNCATED AT 250 WORDS)

Amitriptyline↗
PubMed1985

Randomized clinical trial of one-day surgery. Patient satisfaction, clinical outcomes, and costs.

One hundred and eighty-two patients undergoing tubal ligation, hernia repair, or meniscectomy were randomly assigned to either one-day or inpatient surgery. The study's objective is to compare these two modes of care with regard to patient satisfaction, clinical outcomes, and costs of the episode of care. A significantly higher proportion of one-day patients than their hospitalized counterparts found their stay to be too short and would prefer hospitalization as an alternative. Clinical outcomes were comparable in both groups. One-day tubal ligation and hernia repair were found to be cost-efficient and averaged hospital savings of $86.00 and $115.00 more than inpatient care. Meniscectomy deviated from this trend in that treatment costs were significantly higher for one-day surgery patients. Analysis of personal and physician costs did not show any significant difference between the two modes of care.

Adult↗
PubMed1985

[Traumatic tricuspid insufficiency. Review of the literature, apropos of a case].

The authors report a case of traumatic tricuspid incompetence due to rupture of an anterior pillar and the chordae, associated with pericardial rupture, a first degree atrioventricular block, a persistent complete right bundle branch block and acute recurrent pericarditis. The diagnosis, suggested by echocardiography was confirmed by right cardiac catheterisation. The patient underwent tricuspid plasty six months after the accident. On the basis of a review of the literature, the authors discuss traumatic tricuspid incompetence (its symptoms and associated lesions), the diagnostic methods and the therapeutic approach.

Adult↗
PubMed1984

[Cardiac manifestations of Lyme disease. Apropos of 2 cases].

Lyme disease, a well-known entity in the United States, has featured only rarely in the French literature. We report two cases from the Cardiology Department with acute symptomatic atrio-ventricular block. The illness begins with migratory chronic erythema, which is the best marker of the condition. This is followed by neurological, joint and cardiac manifestations. Cardiac involvement consists essentially in A-V block of varying severity, which rapidly regresses. Until the recent discovery of the arthropod vector responsible (Ixodes dammini), the diagnosis was clinical and was confirmed by negative serological results for the other infectious agents. Penicillin and tetracycline are effective at the skin lesion stage. It is important to recognise this condition since there is no case of complete A-V block lasting longer than 2 weeks.

Adult↗
PubMed1978

[Electrophysiological study of a Portuguese case of amyloidosis with conduction disorders].

Cardiac involvement in the course of familial Portuguese amyloidosis, as apart from the other primary amyloidosis, is characterised by the early and wide-spread intracardiac conduction disorders, and the contrasting late presentation of the clinical signs. A case is presented of Portuguese amyloidosis which was typical from the viewpoint of the neurological disorders, the familial characteristics, and the positive biopsy; the main conduction defects found in primitive amyloidoses are also recalled. The patient described had for many years suffered from first degree heart block, and then presented with lipid changes with syncopal attacks which led to electrophysiological investigation of the conduction defect, no similar example of which has been found in the literature. The severity and widespread nature of the disorders which were found, together with the localisation of a sub-His block led us to implant the pacemaker. We have only found two other patients who had implants for disorders of conduction secondary to cardiac amyloidosis. Emphasis has been laid on the importance of this investigation which, when it leads to the positioning of a pacemaker, should avoid the onset of syncopal attacks and sudden death which together constitute one of the primary causes of mortality in primary amyloidosis. The length of follow-up in our case has been 14 months (April 1977).

Adult↗