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Biomedical subjects

F Victor

Publications and source records attributed to F Victor.

17 recordsLinked to original sources
PubMed2005

Temporomandibular articular disorders can be alleviated with surgery.

DATA SOURCES: Medline, Embase and a variety of other sources were searched for English-language articles. Non-journal publications, conferences proceedings from professional organisations and from private and government agencies were screened. Bibliographies and reference lists from peer-reviewed and 'grey' literature were also reviewed. STUDY SELECTION: To meet the inclusion criteria articles must have reported studies of at least 10 patients, involve diagnoses of disc displacement with reduction (DDwR) or without reduction (DDw/oR) or degenerative joint disease (DJD) and include at least one of the following surgical techniques: arthrocentesis; arthroscopy; discectomy without replacement or disc repair/repositioning. DATA EXTRACTION AND SYNTHESIS: The outcome measured was the proportion of patients who reported improvement after treatment. Study success rates were recalculated on an intent-to-treat basis. Meta-analyses were performed along with meta-regressions where heterogeneity was an issue. Three classes of meta-analyses were performed using different artificial, untreated, control groups assuming three levels of spontaneous improvement, namely 0, 37.5 and 75%. RESULTS: Twenty-two studies, comprising 30 patient groups and sample sizes of 11-237 patients, met the inclusion criteria. For studies of patients with DDwR, at the 0 and 37.5% rates of control group improvement, arthroscopy and disc repair/repositioning resulted in treatment effects significantly greater than zero, with no significant differences in the efficacy of these two surgical techniques. For studies of patients with DDw/OR, the proportion of patients who improved after arthroscopy or arthrocentesis was significantly greater than zero at all three levels of estimated control improvement. Disc repair effect size was not significant at the 75% rate. CONCLUSIONS: Surgical treatments appear to have some efficacy for people who have temporomandibular articular disorders that do not respond to nonsurgical therapies.

Comment↗
PubMed2001

Six year experience of transvenous left ventricular lead implantation for permanent biventricular pacing in patients with advanced heart failure: technical aspects.

BACKGROUND: Biventricular pacing has been proposed as an adjuvant to optimal medical treatment in patients with drug refractory heart failure caused by chronic left ventricular systolic dysfunction and intraventricular conduction delay. OBJECTIVE: To assess the technical feasibility and long term results (over six years) of transverse left ventricular pacing with the lead inserted into a tributary vein of the coronary sinus. SUBJECTS: From August 1994 to February 2000, left ventricular lead implantation was attempted in 116 patients who were eligible for biventricular pacing (mean (SD) age 67 (9) years, New York Heart Association (NYHA) functional class III/IV, left ventricular ejection fraction 22 (6)%, QRS duration 185 (26) ms). RESULTS: The overall implantation success rate was 88% (n = 102). A learning curve was indicated by a progressive increase in success from 61% early on to 98% in the last year. The mean pacing threshold was 1.1 (0.7) V/0.5 ms at the time of implantation and increased slightly up to 1.9 (0.9) V/0.5 ms at the end of the follow up period (15 (13) months). The rate of acute and delayed left ventricular lead dislodgement decreased from 30% in the early years to 11% after 1999. During follow up, 19 patients required reoperation for delayed lead dislodgement or increase in left ventricular pacing threshold (n = 15), phrenic nerve stimulation (n = 3), or infection (n = 3). CONCLUSIONS: Transverse left ventricular pacing through the coronary sinus is feasible and safe. The rate of implantation failure and of lead related problems has decreased greatly with increasing experience and with improvements in the equipment.

Aged↗
PubMed2000

Comparative effects of permanent biventricular pacing for refractory heart failure in patients with stable sinus rhythm or chronic atrial fibrillation.

This study aimed to compare the long-term benefit of biventricular pacing in drug-refractory heart failure in patients with dilated cardiomyopathy who were in stable sinus rhythm or had persistent atrial fibrillation. The results showed that permanent biventricular pacing in such patients significantly improves exercise tolerance in both groups of patients; however, the benefit tended to be greater in patients with atrial fibrillation.

Aged↗
PubMed2000

Cardiac loading conditions modify the ventricular repolarization in conscious dogs with heart failure.

Changes in myocardial loading conditions influence the ventricular action potential via mechanoelectric feedback, a mechanism impaired in pathology. In vivo the QT interval of the electrocardiogram which reflects the action potential duration allows appropriate determination of its modifications. The effects of changes in cardiac loading conditions (load reduction with trinitrin; volume loading with Plasmion) on regional function and ventricular local electrogram were investigated in conscious dogs before (control) and after 4 weeks of rapid pacing (dilated cardiomyopathy, DCM). In controls both interventions increased heart rate. Trinitrin increased end-diastolic wall thickness (EDWth, P<0.001) and reduced absolute QT interval duration (P<0.05). Plasmion decreased EDWth (P<0.001) and increased left ventricular end diastolic pressure (LVEDP, P<0.001) without QT interval alteration. However, the corrected QT interval was unchanged in both interventions. In DCM, trinitrin did not change the QT interval. Plasmion increased LVEDP (P<0.01) and prolonged QT and corrected QT intervals (P<0.01) despite the tachycardia. In controls the changes in cardiac loading conditions did not modify the QT interval, suggesting intact endogenous regulation of repolarization. The impaired adaptation observed in DCM contributed to an increase in QT interval following volume loading. In this model, a prolonged repolarization after abrupt volume loading may result from enhanced or disclosed mechanoelectric feedback.

Animals↗
PubMed1999

Electrocardiographic predictive factors of long-term clinical improvement with multisite biventricular pacing in advanced heart failure.

Biventricular pacing has recently been proposed for treating patients with drug refractory heart failure and intraventricular conduction delay. The purpose is to restore ventricular relaxation and contraction sequences as homogeneously as possible. The aim of this study was to determine if some factors could predict the long-term clinical effectiveness of that new treatment. This study included 26 patients, aged 66 +/- 7 years, with drug refractory heart failure and wide QRS. Patients were implanted with a biventricular pacemaker. The left ventricle was paced through a coronary sinus tributary. New York Heart Association functional class, exercise tolerance, and left ventricular (LV) ejection fraction were collected at baseline and after pacemaker implantation. Patients were divided into 2 groups: group I = responders; group II = nonresponders. QRS duration and axis at baseline and during biventricular pacing, interventricular conduction time, and LV and right ventricular lead positions were compared between the 2 groups. Group I patients (n = 19) had a mean reduction of 1.3 in functional class and an increase in peak oxygen consumption rate by a mean of 50%. The only parameter that differed between the 2 groups was the QRS duration during biventricular pacing, with a significantly shorter value in group I than in group II (154 +/- 17 vs 177 +/- 26 ms; p = 0.016). Thus, a positive response to biventricular pacing is correlated with the quality of electrical resynchronization. The optimal positions of the right and LV leads would be those that could induce the greatest shortening of QRS duration.

Aged↗
PubMed1999

Optimal right ventricular pacing site in chronically implanted patients: a prospective randomized crossover comparison of apical and outflow tract pacing.

OBJECTIVES: To evaluate the long-term functional and hemodynamic effects of right ventricular outflow tract (RVOT) pacing by comparison with right ventricular apical (RVA) pacing. BACKGROUND: Acute studies have suggested that RVOT pacing could significantly improve cardiac performance in comparison with RVA pacing but no data are available in chronically implanted patients. METHODS: Sixteen patients with chronic atrial tachyarrhythmia and complete AV block were included. Left ventricular ejection fraction (LVEF) was > or =40% in ten and <40% in six. Patients were implanted with a standard DDDR pacemaker connected to two ventricular leads. A screw-in lead was placed at the RVOT and connected to the atrial port. A second lead was positioned at the RVA and connected to the ventricular port. Right ventricular outflow tract and RVA pacing was achieved by programming either the AAIR or the VVIR mode respectively. Four months later patients were randomized so as to undergo either RVOT or RVA pacing for three months according to a blind crossover protocol. Apart from the pacing mode, programming remained unchanged throughout the study. At the end of each period, NYHA class, LVEF, exercise time and maximal oxygen uptake were assessed. RESULTS: No significant difference was observed between the two modes for all the parameters analyzed. These identical results were observed in all patients globally, in patients with LVEF > or =40% as in those with LVEF <40%. CONCLUSIONS: Within the limits of this study, no symptomatic improvement or hemodynamic benefit was noted after three months of RVOT pacing, by comparison with RVA pacing.

Aged↗
PubMed1999

Effects of permanent dual-chamber pacing on mitral regurgitation in hypertrophic obstructive cardiomyopathy.

AIMS: To assess the effects of chronic dual-chamber pacing on mitral regurgitation in hypertrophic obstructive cardiomyopathy. METHODS AND RESULTS: Twenty-three patients with hypertrophic obstructive cardiomyopathy and mitral regurgitation. treated with DDD pacing for 16 +/- 14 months, were included in the study. Mitral regurgitation was assessed by Doppler-echocardiography using semi-quantitative analysis (grades I-IV) and by measuring the maximum regurgitant jet area/left atrial area ratio. At the end of follow-up, DDD pacing reduced the outflow gradient from 93 +/- 37 mmHg to 31 +/- 30 mmHg (P<0.0001). Nine of the 14 patients who initially had > or =grade II mitral regurgitation improved by at least one grade, two of them exhibiting dramatic improvement (from grade IV and III to grade I). The regurgitant jet area/left atrial area ratio was reduced with DDD pacing from 20 +/- 13% to 11 +/- 6% (P<0.0001). Patients who had significant mitral regurgitation despite pacing were those whose outflow gradient remained high or those with mitral valve organic abnormalities (mitral annulus calcification or mitral valve prolapse). In the absence of organic abnormalities other than leaflet elongation, there was a significant correlation between the gradient value achieved with DDD pacing and the extent of mitral regurgitation (P<0.05). CONCLUSION: In the absence of organic mitral valve abnormalities, DDD pacing reduces in parallel mitral regurgitation and left ventricular outflow gradient. In such patients therefore, significant mitral regurgitation is not a contraindication to pacing.

Adult↗
PubMed1999

Pacemaker lead infection: echocardiographic features, management, and outcome.

OBJECTIVE: To compare transthoracic and transoesophageal echocardiography (TTE, TOE) in patients with permanent pacemaker lead infection and to evaluate the safety of medical extraction in cases of large vegetations. METHODS: TTE and TOE were performed in 23 patients with definite pacemaker lead infection. Seventeen patients without previous infection served as a TOE reference for non-infected leads. RESULTS: TTE was positive in seven cases (30%) whereas with TOE three different types of vegetations attached to the leads were visualised in 21 of the 23 cases (91%). Of the 20 patients with vegetations and lead culture, 17 (85%) had bacteriologically active infection. Left sided valvar endocarditis was diagnosed in two patients. In the control group, strands were visualised by TOE in five patients, and vegetations in none. Medical extraction of vegetations >/= 10 mm was performed in 12 patients and was successful in nine (75%) without clinical pulmonary embolism. After 31.2 (19.1) months of follow up (mean (SD)), all patients except one were cured of infection; three died from other causes. CONCLUSIONS: Combined with bacteriological data, vegetations seen on TOE strongly suggest pacemaker lead infection. Normal TTE examinations do not exclude this diagnosis because of its poor sensitivity. Medical extraction of even large vegetations appeared to be safe.

Adult↗
PubMed1997

Antirhino/enteroviral vinylacetylene benzimidazoles: a study of their activity and oral plasma levels in mice.

In an effort to find an orally bioavailable antiviral for the treatment of rhino/enteroviral infections, a series of vinylacetylene benzimidazoles (11a-o, 12, and 18a) was made. Initial studies of this class of antivirals showed that fluorine substitution on the left-hand phenyl ring in combination with the vinylacetylene moiety gave the requisite mix of physical properties to achieve good in vitro antiviral activity as well as respectable oral bioavailability in rhesus monkeys. To ascertain the generality of this finding and to broaden the scope of the structure-activity relationship (SAR), the present study concentrated on fluoro substitution of this class of molecules. The initial antiviral activity for each analogue was measured using human rhinovirus 14 (HRV-14). This served as an indicator of general antiviral activity for SAR purposes. Subsequently, the spectrum of antirhino/enteroviral activity of the more interesting analogues was evaluated through testing against a panel of seven additional rhino/enteroviruses. Broad-spectrum activity was present and consistent for all analogues tested, and it tracked closely with the antiviral activity observed against HRV-14. A simple screening protocol for oral bioavailability was established whereby compounds were administered orally to mice and plasma levels were measured. This procedure facilitated the evaluation of numerous analogues in a rapid manner. The Cmax was used as a measure of oral bioavailability to allow relative ranking of compounds. In general, fluorine substitution directly on the left-hand aromatic ring does give good oral blood levels. However, fluorine incorporation at other positions in the molecule was not as effective at maintaining either the activity or the oral plasma levels. The constructive combination of activity and oral plasma levels was maximized in three derivatives: 11a,e,g.

Administration, Oral↗
PubMed1997

Synthesis and antiviral activity of C2 analogs of enviroxime: an exploration of the role of critical functionality.

Enviroxime is a potent antiviral agent with broad spectrum activity in tissue culture against both rhinoviruses and enteroviruses. We have synthesized and studied a series of C2-substituted analogs in order to identify critical functionality and examine its role in antiviral activity. We have found that primary amino substitution is the most active. Ab initio calculations indicate that larger groups at C2 may provide a repulsive steric interaction at N3, and in those cases where this undesirable conformation has limited flexibility, the antiviral activity is severely reduced. Further the results show that an amino hydrogen at C2 is strongly hydrogen bonded to the N1 sulfonyl oxygen, which in the case of Enviroxime may act to enhance the activity by holding the second hydrogen in a desirable orientation for interaction at an antiviral site.

Antiviral Agents↗
PubMed1997

Synthesis, antiviral activity, and biological properties of vinylacetylene analogs of enviroxime.

A series of vinylacetylene analogs of Enviroxime (1) was synthesized. The new compounds are potent inhibitors of poliovirus in tissue culture. Cross-sensitivity with Enviroxime-derived mutants shows that the new compounds have the same mechanism of action as Enviroxime, which involves the viral 3A protein. In studies with Rhesus monkeys, the p-fluoro derivative 12 was found to be unique in providing oral bioavailability. Metabolism studies using hepatic microsomes suggest that this procedure would be a useful in vitro method for selecting the appropriate animal model for testing oral absorption. Compound 12 was found to be efficacious by oral administration in treating a Coxsackie A21 infection in CD-1 mice.

Animals↗
PubMed1995

[Infections on permanent endocavitary pacemaker leads: value of transesophageal echocardiography].

The prevalence of infection of permanent pacing material ranges from 0.13 to 19.9% of patients according to published series. The seriousness of this condition requires early diagnosis and treatment. Transesophageal echocardiography visualised vegetations on the intracardiac pacing lead in all of 11 patients studied, whereas transthoracic echocardiography and polynuclear leucocyte scintigraphy only provided positive diagnoses in 4 cases for each investigation. Three types of vegetation were visualised; no cases of tricuspid valve endocarditis were observed. Treatment was based on explantation of all implanted material by endovascular traction in 7 cases and by surgery in the other 4 cases according to the results of transesophageal echocardiography. There were no deaths or recurrence of infection. Transesophageal echocardiography is the investigation of choice for imaging a vegetation on an endocavitary pacing lead. Complete explanation is essential for a complete recovery of this infection.

Adult↗
PubMed1990

Evaluation of the anti-influenza virus activities of 1,3,4-thiadiazol-2-ylcyanamide (LY217896) and its sodium salt.

1,3,4-Thiadiazol-2-ylcyanamide (LY217896) and its sodium salt were shown to be effective against influenza A and B viruses in vitro and in the mouse model. In nondividing confluent MDCK cells, the 50% inhibitory concentration of LY217896 ranged from 0.37 to 1.19 micrograms/ml against various strains of influenza A virus and from 0.75 to 1.54 micrograms/ml against various strains of influenza B virus, with no apparent cytotoxicity. However, at a concentration of 0.31 microgram/ml, LY217896 inhibited the replication of dividing MDCK cells. LY217896 (9 mg/m2 of body surface area per day) administered in the diet, in the drinking water, by oral gavage, by intraperitoneal injection, or by aerosolization was well tolerated and protected CD-1 mice infected with a lethal dose of influenza A or B virus. Effective administration of the compound could be delayed for up to 96 h postinfection. Virus titer was reduced by 1 to 2 log10 units in lungs of mice given LY217896 in the drinking water. Mice treated initially with protective levels of LY217896 were resistant to a subsequent challenge of influenza virus in the absence of the compound, indicating that the animals were able to develop immunity to the initial infection. Administration of LY217896 to uninfected mice did not induce interferon-like activity or interfere with natural killer cell function. In the ferret, LY217896 was effective in preventing fever induced by influenza virus.

Animals↗
PubMed1988

Imidazo[1,2-a]pyrimidines and imidazo[1,2-a]pyrazines: the role of nitrogen position in inotropic activity.

Congestive heart failure is a major medical problem for which existing medicaments have provided limited benefit. Recent new experimental drugs, including imidazo[4,5-b]- and imidazo[4,5-c]pyridines, have both inotropic and vasodilatory properties. Subtle changes in nitrogen position of these compounds have been shown to dramatically affect potency. We have synthesized a series of imidazo[4,5-b]- and -[4,5-c]pyridine analogues having an imidazo nitrogen relocated at the bridgehead position. The superior inotropic activity of the [4,5-c]pyridines as compared to [4,5-b]pyridines is reaffirmed by the activity of our analogues. The biological equivalence of imidazo[4,5-b]pyridines with imidazo[1,2-a]pyrimidines and imidazo[4,5-c]pyridines with imidazo[1,2-a]pyrazines is demonstrated. Further, 2-[2-methoxy-4-(methylsulfenyl)phenyl]imidazo[1,2-a]pyrazine and 2-[2-methoxy-4-(methylsulfonyl)phenyl]-imidazo[1,2-a]pyrazine are potent inotropic agents both in vitro and in vivo.

Animals↗