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Biomedical subjects

M Abbar

Publications and source records attributed to M Abbar.

At least 19 recordsLinked to original sources

[Venlafaxine withdrawal syndrome: report of six cases and review of the literature].

INTRODUCTION: Venlafaxine is an antidepressant that selectively inhibits serotonin reuptake and is a norepinephrine inhibitor. Withdrawal syndromes can occur after abrupt drug discontinuation of long-term regimens. EXEGESIS: We report six cases of withdrawal symptoms after venlafaxine discontinuation. CONCLUSION: Physicians must be aware of the frequency, rapidity and potent severity of these withdrawal syndromes.

Adult

Overdose with sustained-release lithium preparations.

Acute lithium intoxication is potentially lethal. Compared to conventional lithium preparations, sustained-release lithium formulations present specific problems for medical practice in the case of overdose. We report a case of intoxication with 8000 mg of sustained-release lithium carbonate preparation (Teralithe 400 LP(R)). Twenty-five hours after the ingestion, the patient was still asymptomatic, despite a serum level in the toxic range. After comparison of this case with reports found in the Medline database, we consider the clinical management of such cases.

Adult

Clozapine and metabolite concentrations during treatment of patients with chronic schizophrenia.

Results presented in this article are focused on the variability in pharmacokinetics. The purpose of this study was (1) to investigate intra- and interindividual variabilities of pharmacokinetic parameters of clozapine and its two main metabolites in plasma after multiple oral administration in 8 chronic schizophrenic patients (Study 1) and (2) to gain more information regarding plasma concentrations of these drugs after multiple doses in a group of 25 treatment-responsive patients (Study 2). Patients were treated with clozapine in fixed daily doses (given every 8-12 hours) between 200 and 900 mg. Plasma drug concentrations were determined by high-performance liquid chromatography. The mean volume of distribution and the total plasma clearance of clozapine, uncorrected for bioavailability, were 7 L/kg and 40.5 L/h, respectively. The terminal elimination half-lives averaged 10.5 hours for clozapine, 19.2 hours for norclozapine, and 8.6 hours for the N-oxide metabolite. Significant relationships were observed between clozapine and norclozapine (or clozapine N-oxide) plasma concentrations. Large inter- and intrapatient variations in pharmacokinetics were observed. Clozapine was generally well tolerated by the patients, with sedation, hypersialorrhea, and tiredness as the most common side effects encountered.

Adult

Multiple-dose pharmacokinetics of clozapine in patients with chronic schizophrenia.

The pharmacokinetic parameters of clozapine and its two main metabolites, N-desmethylclozapine (norclozapine, active metabolite) and clozapine N-oxide, were evaluated, after oral administration, in 19 patients with chronic schizophrenia. Plasma and red blood cell (RBC) drug concentrations were determined by high-performance liquid chromatography. Large interpatient variations in pharmacokinetic parameters of clozapine and its two metabolites were observed. Plasma clozapine concentration peaked, on average, at 2.3 hours. The mean volume of distribution and the total plasma clearance, uncorrected for bioavailability, were 6 L/kg and 38 L/hr, respectively. The terminal elimination half-lives averaged 7.6 hours for clozapine, 13 hours for norclozapine, and 7 hours for the N-oxide metabolite. The mean RBC/plasma concentration ratios were 23, 61, and 81% for clozapine, N-desmethylclozapine, and clozapine N-oxide, respectively. From RBC concentration data, the mean elimination half-lives were 7.6 hours for clozapine, 16 hours for N-desmethylclozapine, and 8 hours for the N-oxide metabolite. The average value for blood clearance of clozapine was 54.7 L/hr. Significant correlations were observed between dose and maximum plasma concentrations and between dose and area under the curve concentrations; these results suggested linear steady-state pharmacokinetics over the range of concentrations studied.

Adolescent

Manic depressive illness and tyrosine hydroxylase gene: linkage heterogeneity and association.

Several studies have implicated the tyrosine hydroxylase (TH) locus within the 11p15 region in susceptibility to manic depressive illness (MDI). This possibility was further investigated by both parametric (lod score) and nonparametric (affected-pedigree-member and a case-control study) methods of analysis in 11 French MDI families and in a sample of 200 unrelated subjects. Both types of analyses corroborate the implication of this locus, and positive lod scores were obtained in two families, which most likely reflects genetic heterogeneity. Statistical analyses were also performed including available data from published reports. These analyses, which allowed for genetic heterogeneity, substantiated our findings. The combined maximum lod score for all the families studied was 3.68 at theta = 0.00 (number of families: 36) assuming heterogeneity (alpha = 15%, P = 0.01). Taken together these results converge to suggest that the risk factors for MDI lie in the 11p15 region with TH being the most likely candidate gene.

Alleles

[Epidemiologic and molecular genetic of suicidal behavior].

The current understanding of suicidal behaviors is that such behaviors are multidetermined and mental state and trait related. Genetic factors appear to be of great importance, as suggested by the findings of family, twin, and adoption studies. Whether these genetic factors are similar to those involved in the susceptibility to psychiatric disorders closely related to suicidal behavior (eg, manic depressive illness, schizophrenia or substance use disorders) is yet unknown. However, a genetic factor of susceptibility to suicide, independent or additive to the genetic transmission of the psychiatric disorders that are related to suicidal behavior, is strongly suggested by the data of the Copenhagen adoption study and a study of Amish families. Recently, new approaches have been proposed to identify the genetic component of such complex traits. Association studies between genetic markers and a disease phenotype has been successfully applied to several complex disease such as essential hypertension. One candidate gene for suicidal behaviors is the tryptophane hydroxylase (TPH) gene which is the first and possibly rate-limiting enzyme of the metabolic pathway for serotonin. Indeed, altered serotoninergic function in both completed suicide and suicide attempt has been one of the most replicated findings in modern biological psychiatry. In our knowledge, only two studies have tested the association between suicide attempt and the TPH gene and their authors found negative results. Despite these negative results, association studies that use candidate gene remain one of the methods of choice for studying the genetic component of suicidal behaviors.

Depressive Disorder

[Panic disorder and panic attack].

Panic disorder first appeared as a specific diagnostic entity in 1980, in the third Edition of "Diagnostic and Statistical Manual of Mental Disorders" (DSM III). The classical anxiety neurosis was divided into two separate entities: panic disorder and generalized anxiety disorder, whose major criteria for distinction was based, in a simplified manner, on the presence or absence of panic attacks in the patient's history. Validity of the concept of panic disorder as a clinical and autonomous entity is now widely accepted. It is based on numerous epidemiological, phenomenological, biological, genetic and therapeutic studies that have established, that panic disorder may be clearly distinguished from other anxiety and mood disorders. However, this disorder still has unknown aetiology and criteria for definition remain purely clinical. Controversies as regards the validity of diagnostic criteria for panic disorders may account for its successive definitions in the DSM III-R, then in the DSM IV. In fact, in contrast to the definition of panic attacks that has remained practically constant, panic disorder was initially defined by the recurrence of panic attacks. It is now considered by the authors of the DSM IV as a disorder characterized by a chronic anxiety, focused on the risk for panic attacks showing symptoms evocative of autonomic dysregulation. In the DSM IV, panic attack is now considered as a syndrome which is not specific for panic disorder. Panic disorder may be diagnosed in a patient who has suffered from recurrent panic attacks, provided that one at least of the latter have been associated with one of the following symptoms: persisting fear from other panic attacks; concerns about possible implications of panic attacks or their consequences; major behavioural changes related to the attacks. Evolving positions of the successive authors of the DSM contrast with more conservative attitudes of the authors of the CIM 10, who still consider agoraphobia as a key symptom. Whatever the issues of these definitions, it must be kept in mind that panic disorder is a severe syndrome, and leads to major suffering and significant impairment of the patients' quality of life as well as their social life and interpersonal relationships. Comorbidity with depressive and addictive disorders is frequent, and panic disorder is considered by numerous authors as a risk factor for suicide. Due to the severity of panic disorder, its frequency and the fact that it is too often undiagnosed (although there are effective therapeutic strategies), efforts are fully warranted, so that patients may benefit from early diagnosis and adequate treatment.

Anxiety Disorders

Suicidal behaviors and the tryptophan hydroxylase gene.

BACKGROUND: To determine whether the tryptophan hydroxylase gene (ie, the gene that codes for the rate-limiting enzyme in the metabolic pathway of serotonin) may be a susceptibility factor for suicidal behavior. METHODS: Genotypic and allelic frequencies at a polymorphic Ava II restriction site were revealed with the use of the complementary DNA tryptophan hydroxylase probe C2-38 in 62 suicide attempters. The psychiatric characteristics of these suicide attempters were determined using the Schedule for Affective Disorders and Schizophrenia-Lifetime version with modification for the study of anxiety disorders, and these characteristics were compared with those in 52 healthy controls. RESULTS: No association between tryptophan hydroxylase and suicidal behavior was detected. CONCLUSION: The tryptophan hydroxylase gene was not a susceptibility factor for suicidal behaviors in the group of suicide attempters in this study.

Alleles

[Treatment of depression: methods and stages].

According to recent epidemiological studies, the lifetime prevalence of major depression ranges between 10 and 20%. However, informations concerning the course of depressive illness remain limited. It appears that only about one-quarter, or even less, of all depressives are affected once in their lifetime. Today, it could be assumed that 75-80% of depressive cases are recurrent. Many antidepressive treatments are available today, including first generation and second-generation antidepressants, psychotherapies, and sismotherapies. While antidepressants are similar in terms of drug or efficacy, onset of action, and latency to treatment response, their potential side effect and toxicity profiles are quite different. These factors must be weighed before treatment of depression is begun in an effort to prescribe the compound that is most beneficial i.e., clinically effective while exhibiting the fewest negative aspects. Determination of patients with an "at-risk" profile for drug side effects is best done by a careful analysis of their medical history, comorbidity with other axis I and axis II disorders and concomitant drug therapies. In fact, it appears that depressive patients with coexisting anxiety are often prone to side effects either with tricyclic compounds and SSRI's. In these patients these medications should therefore be introduced at a low dose and slowly increased. Otherwise, because of the frequent comorbidity of depression and alcoholic disorders, the clinician should make very effort to obtain a detailed history of the patient's substance use. If the patient is found to have a substance use disorder, a program to secure abstinence should be regarded as a priority in the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Antidepressive Agents

[The contribution of endoscopy in the diagnosis of unilateral hematuria of renal origin and pseudotumors of the upper urinary tract].

From 1985 to 1992, 9 patients (6 males, 3 females) with a mean age of 47 years, presenting with a clinical picture suggestive of a tumour of the upper urinary tract (haematuria and/or pelvic or caliceal radiolucent filling defect), underwent retrograde (6 cases) and/or percutaneous (9 cases) endoscopic exploration of the upper urinary tract. The percutaneous examination allowed a precise diagnosis and appropriate treatment adapted to the lesion detected (papillary necrosis: 2 cases; ectopic papilla: 2 cases; hypertrophy of Brunn's nests: 1 case; papillary angioma: 1 case; haemorrhagic papillitis: 3 cases) in every case. Endoscopic exploration of radiolucent lesions of the upper tract and unexplained renal haematuria is therefore justified whenever the diagnosis of upper tract tumour is uncertain on the basis of the radiological and cytological assessment.

Adult

[A quiet revolution: the Wallstent urethral prosthesis (Urolume AMS)].

14 patients (mean age: 57 years) with posterior urethral stricture were treated by internal urethrotomy and implantation of one or several Wallsten prostheses. The stent had to be removed in 2 patients (15%), while 12 patients (85%) obtained satisfactory urethral patency (mean follow-up: 17.5 months). Complications were observed in 50% of cases. They were able to be treated endoscopically with a satisfactory result in 5 out of 6 cases (intraprosthetic calculi or stenosis of the ends of the stent; 2 patients who became incontinent after insertion of the stent regained normal continence after insertion of an artificial sphincter above the stent. The Wallsten endoprosthesis therefore appears to be a very satisfactory treatment for recurrent complex strictures of the posterior urethra.

Adult

[Psychosocial stress factors and suicidal acts].

Suicidal behaviour is actually understood as being multidetermined and the result of an interaction between state and trait related effects. Several types of risk factors have been extensively studied: psychiatric and personality disorders, genetic variables, biological factors and psychosocial stressors, the latter being the purpose of this review. Social and familial factors, negative life events and medical illness may interact with the factors mentioned above in three main ways to produce suicidal acts: as predisposing factors increasing vulnerability, as precipitating or as contributing factors. A summary of social and clinical studies will be presented and implications for medical care and prevention will be discussed.

Depressive Disorder

[Fragmentation of urinary calculi using the Lithoclast EMS. Technique and results].

The Lithoclast is an endoscopic lithotriptor which uses the ballistic energy produced by a small hand-held apparatus, by the movement of a small metal part (the projectile) driven by a jet of compressed air. The energy is transmitted to a metal rod whose diameter is selected according to the application: 0.8 or 1 mm in the ureter; 2 mm in the bladder and kidney. We have used this apparatus to treat 40 stones in 39 patients (25 ureteric stones, 11 renal stones, 4 bladder stones). Satisfactory fragmentation was obtained for 39 of the 40 stones (97.5%). The apparatus is very easy to use in the kidney and bladder (the risk of urinary tract perforation is very low at this level). The risk of perforation of the ureteric wall by 0.8 mm or 1 mm rods is considerable (12% of cases), but these punctate lesions heal rapidly over a double J stent. Special techniques should be used in the ureter to limit the risk of pushing the stone towards the renal pelvis.

Adult

Evidence for a pseudoautosomal locus for schizophrenia. II: Replication of a non-random segregation of alleles at the DXYS14 locus.

Because of an association between sexual aneuploidies and schizophrenia, and because schizophrenic siblings have been found to be more often of the same than of the opposite sex, the susceptibility locus for schizophrenia is thought to lie within the pseudoautosomal region of the sex chromosomes. We analysed 33 sibships comprising 18 pairs, 13 trios, and 2 quartets of affected siblings, and found support for non-random segregation of of alleles at the DXYS14 locus in affected siblings. These findings are consistent with the pseudoautosomal hypothesis for schizophrenia and favour a genetic linkage between DXYS14 and the disease.

Alleles