Biomedical subjects

Kurt Hornik

Publications and source records attributed to Kurt Hornik.

11 recordsLinked to original sources

PubMed2004

Bioconductor: open software development for computational biology and bioinformatics.

The Bioconductor project is an initiative for the collaborative creation of extensible software for computational biology and bioinformatics. The goals of the project include: fostering collaborative development and widespread use of innovative software, reducing barriers to entry into interdisciplinary scientific research, and promoting the achievement of remote reproducibility of research results. We describe details of our aims and methods, identify current challenges, compare Bioconductor to other open bioinformatics projects, and provide working examples.

Computational Biology↗

PubMed2004

Efficacy of fluvoxamine in preventing relapse in alcohol dependence: a one-year, double-blind, placebo-controlled multicentre study with analysis by typology.

Patients with a diagnosis of alcohol dependence, detoxified and abstinent for 10-30 days, were randomly allocated to placebo or the serotonin reuptake inhibitor, fluvoxamine (up to 300 mg per day), plus counselling and support. In the intention to treat sample of 493, there was a trend for the fluvoxamine group to do worse than the placebo group on the primary outcome criteria: abstinence; and relapse defined as drinking > or =5 units on an occasion and > or =4 such occasions in a week, or > or =12 units on an occasion (1 unit = 9g ethanol). When typology of alcoholism was assigned by scores on the Tridimensional Personality Questionnaire, Types I and II had similar rates of survival without relapse on placebo (PLC I: 19.3%, n = 135; PLC II: 18.2%, n = 110), but on fluvoxamine Type II did worse than Type I (FLU I: 13.7%, n = 131; FLU II: 6.14%, n = 114) (P < 0.01). When typology was assigned on the basis of age of onset of alcohol problems (< or = age 25, or > age 25), early-onset patients in the fluvoxamine group relapsed more frequently than late-onset patients in that group (no longer significant after adjustment for gender), as did those who commenced regular drinking before age 25 (both with and without adjustment for gender). One explanation for our finding could be that impulsivity in early-onset or Type II patients may be accentuated by serotonin enhancement.

Adult↗

PubMed2004

Guided self-help versus cognitive-behavioral group therapy in the treatment of bulimia nervosa.

OBJECTIVE: The aim of the current study was to evaluate whether guided self-help was effective in the short and long term in the treatment of bulimia nervosa. METHOD: Eighty-one patients with bulimia nervosa were randomly assigned to either a self-help manual with a maximum of 18 short weekly visits (guided self-help) or to 18 weekly 1.5-h sessions of cognitive-behavioral group therapy (CBT). The primary outcome variables were monthly frequencies of self-reported binge eating and vomiting episodes. Secondary outcome variables were eating disorder-related psychopathology (assessed with the Eating Disorders Inventory [EDI]) and depression (assessed by the Beck Depression Inventory [BDI]). Patients were followed up 1 year after the end of treatment. RESULTS: A mixed-effects linear regression analysis indicated that subjects in both treatment conditions showed a significant decrease over time in binge eating and vomiting frequencies, in the scores of the EDI subscales, and in the BDI. Both treatment modalities led to a sustained improvement at follow-up. A separate analysis of the completer sample showed significantly higher remission rates in the self-help condition (74%) compared with the CBT condition (44%) at follow-up. CONCLUSIONS: Guided self-help incorporating the use of a self-help manual offers an approach that can be effective in the short and long-term treatment of bulimia nervosa.

Adolescent↗

PubMed2004

A quantitative comparison of functional MRI cluster analysis.

The aim of this work is to compare the efficiency and power of several cluster analysis techniques on fully artificial (mathematical) and synthesized (hybrid) functional magnetic resonance imaging (fMRI) data sets. The clustering algorithms used are hierarchical, crisp (neural gas, self-organizing maps, hard competitive learning, k-means, maximin-distance, CLARA) and fuzzy (c-means, fuzzy competitive learning). To compare these methods we use two performance measures, namely the correlation coefficient and the weighted Jaccard coefficient (wJC). Both performance coefficients (PCs) clearly show that the neural gas and the k-means algorithm perform significantly better than all the other methods using our setup. For the hierarchical methods the ward linkage algorithm performs best under our simulation design. In conclusion, the neural gas method seems to be the best choice for fMRI cluster analysis, given its correct classification of activated pixels (true positives (TPs)) whilst minimizing the misclassification of inactivated pixels (false positives (FPs)), and in the stability of the results achieved.

Algorithms↗

PubMed2004

Serotonin transporter promoter gene polymorphic region (5-HTTLPR) and personality in female patients with seasonal affective disorder and in healthy controls.

Serotonergic pathways have been related to altered personality patterns in seasonal affective disorder (SAD). The short allele (s) of a polymorphism in the serotonin transporter promoter gene (5-HTTLPR) has been associated with neuroticism and anxiety-related personality traits in healthy volunteers. We investigated personality and 5-HTTLPR in female SAD patients using the Temperament and Character Inventory (TCI). TCI was completed by 56 female patients and 76 age-matched female controls. DNA was genotyped using polymerase chain reaction methods. Subjects homozygous for the long allele (l) were compared to s carriers. Females with SAD had higher scores in Harm Avoidance and lower scores in Novelty Seeking, Self-Directedness and Cooperativeness when compared to controls. Patients carrying the s allele had lower Self-Directedness scores. Our data indicate that females with SAD show altered personality traits. The s allele was associated with lower Self-Directedness scores in SAD patients, whereas there were no significant differences in TCI dimensions between patients and controls in carriers of the long allele.

Adult↗

PubMed2004

Life after death: posttraumatic stress disorder in survivors of cardiac arrest--prevalence, associated factors, and the influence of sedation and analgesia.

OBJECTIVE: Cardiac arrest is possibly one of the most traumatizing conditions for patients, but to date, its influence on psychic morbidity remains unknown. Posttraumatic stress disorder is a unique symptom configuration after an extreme event consisting of intrusion re-experiencing, avoidance and numbness, and hyperarousal symptoms. We studied a) the prevalence of posttraumatic stress disorder (PTSD) in long term survivors of cardiac arrest; b) the role of specific stress factors related to cardiac arrest for the development of PTSD; and c) the influence of sedation and analgesia during or after cardiac arrest on the occurrence of PTSD. DESIGN: Prospective, cohort study. SETTING: University teaching hospital. PATIENTS: Analysis was performed in cardiac arrest survivors who were discharged with favorable neurologic outcome during an 8-yr period (1991-1999). INTERVENTIONS: All patients received the Davidson Trauma Score for the assessment of PTSD and a modified German version of the EuroQol questionnaire for assessment of quality of life. Cardiac arrest circumstances and administration of sedation and analgesia were assessed. MEASUREMENTS AND MAIN RESULTS: Of 1,630 initially resuscitated patients, 270 patients were discharged with good neurologic outcome. A total of 226 patients were contacted, and 143 patients (63% of all eligible patients) completed the study. Mean time from cardiac arrest to follow up was 45 months (range, 24-66). Thirty-nine patients (27%; 95% confidence interval, 21% to 35%) had a Davidson Trauma Score >40 and fulfilled criteria for PTSD. Patients with PTSD had a significantly lower quality of life. The only independent risk factor for the development of PTSD was younger age. There was no difference between patients with or without PTSD regarding the use of sedation and analgesia during or after cardiac arrest. CONCLUSION: The prevalence of PTSD in cardiac arrest survivors is high. Besides younger age, neither clinical factors nor the use of sedation and analgesia were associated with development of PTSD.

Adult↗

PubMed2003

A robust subspace algorithm for principal component analysis.

We present a noise robust PCA algorithm which is an extension of the Oja subspace algorithm and allows tuning the noise sensitivity. We derive a loss function which is minimized by this algorithm and interpret it in a noisy PCA setting. Results on the local stability analysis of this algorithm are given and it is shown that the locally stable equilibria are those which minimize the loss function.

Algorithms↗

PubMed2002

Genome scan for susceptibility loci for schizophrenia and bipolar disorder.

BACKGROUND: Despite the widely accepted view that schizophrenia and bipolar disorder represent independent illnesses and modes of inheritance, some data in the literature suggest that the diseases may share some genetic susceptibility. The objective of our analyses was to search for vulnerability loci for the two disorders. METHODS: A genomewide map of 388 microsatellite DNA markers was genotyped in five schizophrenia and three bipolar disorder Austrian families. Linkage analyses was used to compute the usual parametric logarithm of the likelihood of linkage (LOD) scores and nonparametric linkage analysis (NPL scores Z(all)) was used to assess the pattern of allele sharing at each marker locus relative to the presence of the disease (GENEHUNTER). Affected status was defined as severe affective disorder or schizophrenia. RESULTS: Across the genome, p values associated with NPL scores resulted in evidence (i.e., p <.0007) for linkage at marker D3S1265 on chromosome 3q (NPL score Z (all) = 3.74, p =.0003). Two other markers (on 3q and 6q) showed p values of <.01. CONCLUSIONS: We detected a potential susceptibility locus for bipolar disorder and schizophrenia on chromosome 3q, which has not been reported previously. The possibility of a false positive result has to be taken into account. Our data suggest shared loci for schizophrenia and bipolar affective disorders and are consistent with the continuum model of psychosis.

Austria↗

PubMed2002

Role of family history and 5-HTTLPR polymorphism in female seasonal affective disorder patients with and without premenstrual dysphoric disorder.

Seasonal affective disorder (SAD) and premenstrual dysphoric disorder (PMDD) share many clinical features, and have been associated with brain serotonin dysfunction. Females with SAD frequently fulfil the diagnostic criteria for PMDD. A polymorphism in the serotonin transporter promoter gene (5-HTTLPR) has been associated with SAD. We investigated the role of family history and 5-HTTLPR in female SAD patients with and without PMDD. Forty-four SAD females with, and 43 SAD females without PMDD, were genotyped for 5-HTTLPR. Family history of affective disorders in first degree relatives was assessed. An association between the presence of PMDD and family history (P=0.0029) and 5-HTTLPR long/short allele-heterozygosity (P=0.033) was found in females with SAD. PMDD and SAD may share genetic vulnerability factors, one candidate gene being 5-HTTLPR. The elevated rate of affective disorders in relatives of patients with SAD and PMDD suggests higher genetic vulnerability in this subgroup when compared to patients with SAD alone.

Adult↗

PubMedDate not supplied

Possible linkage of schizophrenia and bipolar affective disorder to chromosome 3q29; a follow-up.

The present linkage study is a follow-up within the chromosome 3q29 region in schizophrenia and bipolar affective disorder families, based on our recently published genome scan, resulting in evidence for linkage of both disorders to this region (marker D3S1265: NPL [non parametric lod] score Z(all)=3.74, P=0.003). Using the same family sample (five pedigrees with schizophrenic index patients and three pedigrees with index bipolar disorder patients N=86; 50 of them were available for genotyping), genotyping of eight additional markers close to D3S1265 was done. Five of those new markers (three centromeric and two telomeric of D3S1265) spanning 4.14 cM (centiMorgan) could be used for statistical analyses ("new markers"). Moreover, marker D3S1265, genotyped within the published genome scan, was used for additional calculations. Linkage analysis was performed using the GENEHUNTER program version 2.1r3. Within newly genotyped markers the highest NPL score Z(all) observed was 1.93296 with the telomeric SNP (single nucleotide polymorphism) rs1835669, corresponding to P=0.032166. Statistical analysis including D3S1265, located in between the newly genotyped markers, resulted in a peak NPL score Z(all)=4.00179 with marker D3S1265, that is P=0.000128. Doing subset analyses of the bipolar disorder and schizophrenia families separately with new markers and D3S1265, linkage signals arose substantially from bipolar disorder families, with contribution from schizophrenia families, too. The results of our follow-up study support our previous linkage finding of schizophrenia and bipolar affective disorder to chromosome 3q29.

Adult↗

PubMedDate not supplied

Anxiety as a predictor of relapse in detoxified alcohol-dependent patients.

AIMS: To evaluate the impact of mood, affect, and personality on predicting relapse in detoxified alcohol-dependent patients to uncontrolled drinking during a 1-year treatment study. METHODS: A total of 521 patients with a DSM-III-R diagnosis of alcohol dependence, excluding those with major depressive disorder, took part in a European multicentre study (11 centres in the United Kingdom, Irish Republic, Switzerland, and Austria). Depressive symptoms were assessed using the Hamilton Depression Scale, whereas symptoms of anxiety were measured using the 'STAI-X2' of the self-rating scale State-Trait Anxiety Inventory and personality traits were measured by the Tridimensional Personality Questionnaire. RESULTS: High anxiety as a stable trait, and personality traits such as high novelty seeking and low harm avoidance covering exploratory excitability, impulsiveness, extravagance, disorderliness and uninhibited optimism, predicted relapse. CONCLUSIONS: These measures could have a direct clinical application for predicting relapse to uncontrolled drinking in male and female detoxified alcohol-dependent patients. The findings indicate the importance of additional therapeutic treatment.

Adult↗