PubMed Health⌕ Search

Biomedical subjects

Y Güzelcan

Publications and source records attributed to Y Güzelcan.

5 recordsLinked to original sources

[Clozapine-induced agranulocytosis: genetic risk factors and an immunologic explanatory model].

BACKGROUND: Clozapine, an atypical antipsychotic used in the treatment of refractory schizophrenia, causes agranulocytosis in 0.8% of patients. The risk factors for clozapine-induced agranulocytosis (CIA) and the underlying mechanisms are unclear. AIM: To ascertain the genetic and immunological risk factors for CIA, and on the basis of these findings to construct an explanatory model for CIA. METHOD: We reviewed the literature via Medline (from 1966 to May 2004) and EMBASE (from 1980 to May 2004) using the search terms 'clozapine' and 'agranulocytosis'. RESULTS: We found 8 case-control studies that fulfilled our selection criteria. In schizophrenia patients, CIA appeared to be significantly associated with certain haplotypes of HLA (human leukocyte antigens) genes, with the 4b,3d microsatellite alleles of TNF (tumor necrosis factor), with variant genes of HSP 70 (heat-shock protein), and with NQO2 (dihydronicotinamide riboside quinone oxidoreductase) gene polymorphism. Most of these genetic findings are interrelated. Gene abnormalities of this kind probably play an important aetiological role in CIA and may provide a basis for the construction of an immuno-toxic explanatory model for CIA. CONCLUSION: It seems likely that CIA can be explained on the basis of genetic and immunotoxic factors. The model should help us to understand how agranulocytosis can be caused by various antipsychotics and how it can be treated. However, it is not yet possible to identify patients who are particularly at risk for CIA.

Agranulocytosis↗

[Schizophrenia and the 22q11 deletion syndrome].

In 10-30% of the patients with the 22q11 deletion syndrome (22q11DS), a psychosis develops in adulthood, often schizophrenia. 22q11DS is a common genetic syndrome which is associated with an interstitial deletion at chromosome 22q11. The syndrome is characterised by a variable phenotype which includes cognitive and behavioural problems, in addition to congenital heart and facial anomalies. The presence of 22q11DS represents one of the highest risk factors for the development of schizophrenia. The study of 22q11DS offers a unique opportunity to increase the understanding of the pathogenesis of schizophrenia.

Chromosomes, Human, Pair 22↗

[Mania during the use of a combination preparation with St. John's wort (Hypericum perforatum)].

A 23-year-old woman with no psychiatric history developed acute mania and psychosis while using St. John's wort at a high dosage (Valdispert 'balans', a combination of valerian extract and hypericin). She was diagnosed as having substance-induced mood disorder, with manic features (DSM-IV). Discontinuation of the use of the product and treatment with olanzapine led to complete recovery. No causal relationship between the use of the extract and the mania was established, but the course of the mania does suggest this association. St. John's wort is a popular herbal antidepressant. Hyperforin and hypericin, components of St. John's wort, inhibit synaptosomal serotonin, noradrenaline and dopamine uptake. The mechanism of action of St. John's wort is, however, not yet fully understood. St. John's wort should therefore be used with caution, especially in patients with a bipolar disorder.

Adult↗