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Biomedical subjects

G Schwarzer

Publications and source records attributed to G Schwarzer.

13 recordsLinked to original sources
PubMed2002

Ursodeoxycholic acid and/or antibiotics for prevention of biliary stent occlusion.

BACKGROUND: Malignant biliary obstruction, which requires endoscopic stenting as palliative therapy, is often complicated by clogging of the stent with subsequent jaundice and/or cholangitis. Stent clogging may be caused by microbiological adhesion and biliary stasis. Therefore, antibiotics and choleretic agents like ursodeoxycholic acid (UDCA) have been investigated to see whether they prolong stent patency. OBJECTIVES: To evaluate if UDCA and/or antibiotics may prolong stent patency and survival in patients with strictures of the biliary tract and endoscopically inserted stents. SEARCH STRATEGY: The Trials Register of The Cochrane Hepato-Biliary Group, The Cochrane Library, MEDLINE, Current Contents, EMBASE, and CancerLit were searched until June 2001. Reference lists of the identified articles were checked for further trials. SELECTION CRITERIA: All randomised or quasi-randomised clinical trials investigating UDCA and/or antibiotics in patients with biliary stents were considered for inclusion, regardless of blinding, language, and publication status. DATA COLLECTION AND ANALYSIS: Trial inclusion, quality assessment, and data extraction were performed independently by two reviewers. Principal investigators were contacted for further information. Survival data were combined by using hazard ratios (with 95% confidence interval (95% CI)). MAIN RESULTS: Five non-blinded randomised trials with 258 patients with malignant strictures treated with polyethylene stents were included. Three trials, including 152 patients, investigated a combination of UDCA and antibiotics versus no treatment. The meta-analysis of these three trials does not show a significant treatment effect on the duration of stent patency (hazard ratio (random effects model) 0.58, 95% CI 0.22 to 1.54) or mortality (hazard ratio (fixed effect model) 0.99, 95% CI 0.68 to 1.43). Two trials with 106 patients compared antibiotics with no treatment, one of these trials used a combination of antibiotics and rowachol (an 'alternative' drug of the 'mint' family). The pooled results of these two trials do not show significant effects of antibiotics on the duration of stent patency (hazard ratio (fixed effect model) 0.69 (95% CI 0.37 to 1.30)) or mortality (hazard ratio (fixed effect model) 1.23 (95% CI 0.72 to 2.08). Data concerning duration of hospital stay, frequency of cholangitis, and rate of infectious complications due to selection of antibiotic resistant bacteria strains were not available. REVIEWER'S CONCLUSIONS: Treatment with UDCA and/or antibiotics to prevent clogging of biliary stents in patients with malignant stricture of the biliary tract cannot be recommended routinely on the basis of the existing randomised clinical trials. Further trials are needed with rigorous methodology and sufficient statistical power.

Anti-Bacterial Agents↗
PubMed2002

Granulopoiesis-stimulating factors in the prevention for adverse effects in the therapeutic treatment of malignant lymphoma.

BACKGROUND: Granulopoiesis-stimulating factors (G-CSF and GM-CSF) are being used to prevent febrile neutropenia and infections in the treatment of patients with malignant lymphoma. The question whether G-CSF and GM-CSF improve dose-intensity, tumour response and overall survival in this patient population has not been answered yet. Since the results from single studies are inconclusive a systematic review was required. OBJECTIVES: To undertake a systematic review in patients with malignant lymphoma to determine the effectiveness of G-CSF and GM-CSF to prevent neutropenia, febrile neutropenia, infection, improve quality of life, adherence to the treatment protocol, tumour response, freedom from treatment failure (FFTF), overall survival (OS) and to assess adverse events of G-CSF and GM-CSF. SEARCH STRATEGY: Medline, Embase, CancerLit, the Cochrane Library and smaller databases, Internet-databases of ongoing trials, conference proceedings of the American Society of Clinical Oncology and the American Society of Hematology were searched. We included full-text and abstract publications as well as unpublished data. SELECTION CRITERIA: Randomised controlled trials comparing prophylaxis with G-CSF or GM-CSF versus placebo/no prophylaxis in adult patients with malignant lymphoma undergoing chemotherapy were included in this review. Both study arms had to receive identical chemotherapy and supportive care. DATA COLLECTION AND ANALYSIS: Eligibility and quality assessment, data extraction and analysis were done in duplicate. All authors were contacted to obtain missing data. MAIN RESULTS: We included 11 eligible studies with 1434 randomised patients. Compared with no prophylaxis, G-/GM-CSF significantly reduced the relative risk for severe neutropenia (RR 0.64 [95% CI 0.55-0.75]), febrile neutropenia (RR 0.74 [95% CI 0.62-0.89]) and infection (RR 0.74 [95% CI 0.64-0.85]). There was no evidence for G-/GM-CSF to decrease the number of patients who required iv antibiotics (RR 0.82 [95%CI 0.57-1.18]), to reduce infection related mortality (RR 2.07 [95% CI 0.81-5.34]), or to improve complete tumour response (RR 1.06 [95% CI 0.96-1.16]), FFTF (HR 1.22 [95% CI 0.83-1.80]) and OS (HR 0.98 [95% CI 0.81-1.18]). None of the studies evaluated quality of life parameters. REVIEWER'S CONCLUSIONS: G-CSF and GM-CSF, when given prophylactically in patients with malignant lymphoma undergoing conventional chemotherapy, reduce the risk of neutropenia, febrile neutropenia and infection. However, based on the currently available randomised trials in this clinical setting, there is no evidence for G-/GM-CSF to provide a significant advantage in terms of complete tumour response, FFTF and OS.

Antineoplastic Agents↗
PubMed2001

Modeling face identification processing in children and adults.

Two face identification experiments were carried out to study whether and how children (5-year-olds) and adults integrate single facial features to identify faces. Using the paradigm of the Fuzzy Logical Model of Perception each experiment used the same expanded factorial design, with three levels of eyes variations crossed with three levels of mouth variations as well as their corresponding half-face conditions. In Experiment 1, an integration of facial features was observed in adults only. But, in adjusting the salience of the features varied, the results of Experiment 2 indicate that children and adults evaluated and integrated information from both features to identify a face. A weighted Fuzzy Logical Model of Perception fit the judgments significantly better than a Single Channel Model and questions previous claims of holistic face processing. Although no developmental differences in the stage of the integration of facial information were observable, differences between children and adults appeared in the information used for face identification.

Adult↗
PubMed2001

Increased loosening of cemented straight stem prostheses made from titanium alloys. An analysis and comparison with prostheses made of cobalt-chromium-nickel alloy.

We studied the rate of aseptic loosening of three different types of femoral stems in primary total hip replacement. After a median follow-up of 10.2 years 4/147 CoCrNi (SS77) straight stems (type M.E. Müller) were revised. After a median follow-up of 7.7 years 32/239 Ti-6A1-7Nb (SS77) were revised and after a median follow-up of 5.2 years 52/203 SLS Titanium alloy stems were revised. Whereas the first two stems are of identical design (smooth-blasted, anterior and posterior collar), the SLS stem design is different. Surgical procedure and cementing technique have remained unchanged. There is a significantly higher risk of failure for smaller titanium stem sizes and in males and patients who are physically active. This indicates that the greater elasticity of the Titanium alloy is one of the factors responsible for loosening.

Aged↗
PubMed2001

Statistical analysis of failure times in total joint replacement.

Time to revision is an important criterion describing the quality of implants in total joint surgery. Estimates of failure probabilities are required to inform a patient about the risk of suffering a reoperation. Also, regression models are used for comparing different prosthesis designs. Typically, patients dying before a revision are considered as censored for time to prosthesis failure. We argue that this technique is inadequate for estimation of failure probabilities and insufficient for comparison of different designs. We propose a new approach based on a competing risk model to account for concurrent mortality. We describe differences in the estimation of failure probabilities and in the interpretation of regression models for implant failure. Additionally, we introduce a random effects term in the regression model to account for potential dependencies in the failure times of bilaterally treated patients. The new approach is illustrated with fictitious data and data from an observational study conducted at a specialized hospital in Switzerland.

Aged↗
PubMed2000

On the misuses of artificial neural networks for prognostic and diagnostic classification in oncology.

The application of artificial neural networks (ANNs) for prognostic and diagnostic classification in clinical medicine has become very popular. In particular, feed-forward neural networks have been used extensively, often accompanied by exaggerated statements of their potential. In this paper, the essentials of feed-forward neural networks and their statistical counterparts (that is, logistic regression models) are reviewed. We point out that the uncritical use of ANNs may lead to serious problems, such as the fitting of implausible functions to describe the probability of class membership and the underestimation of misclassification probabilities. In applications of ANNs to survival data, further difficulties arise. Finally, the results of a search in the medical literature from 1991 to 1995 on applications of ANNs in oncology and some important common mistakes are reported. It is concluded that there is no evidence so far that application of ANNs represents real progress in the field of diagnosis and prognosis in oncology.

Decision Support Techniques↗
PubMed2000

Methicillin-resistant Staphylococcus aureus in a teaching hospital: investigation of nosocomial transmission using a matched case-control study.

In early 1996 a hospital-wide methicillin-resistant Staphylococcus aureus (MRSA) epidemic was recognized in a 900-bed university hospital. In order to investigate hospital-specific transmission routes, a case-control study was carried out. Cases and controls were matched for age (+/- 10 years), sex, admission date (+/- 10 days) and clinical department on admission. Data on potential risk factors, were retrieved by chart review. Between June 1996 and February 1997, 67 patients with hospital-acquired MRSA were identified. Molecular typing showed that 85% of the cases carried an indistinguishable strain. The average time at risk for cases and controls was 17.3 and 23.7 days, respectively (P= 0.01). Seventeen patients (25.4%) developed infection. Conditional multivariate regression analysis showed that intensity of care (P= 0.002), number of transfers (P= 0.019), and fluoroquinolone therapy (P= 0.025) were independently associated with acquisition of MRSA. Intensity of care can be considered as a surrogate marker for a number of manipulations which represent the main risk factors for MRSA transmission. Frequent transfers within the hospital hinder, not only the epidemiological analyses, but also efforts to bring an outbreak under control. Our findings give epidemiological support to recent molecular studies which suggest that fluoroquinolone use may increase the transmissibility of MRSA in hospitals.

Adult↗
PubMed2000

[Processes in object categorization during development--differences and similarities with face processing].

Previous research on face processing showed a developmental trend from analytic to holistic processing. This developmental trend was due to increasing knowledge about faces with increasing age. In contrast, research on object processing revealed that analytic processing could occur in any age group. The goal of the present study was to test to what extent objects that are familiar to children could also induce holistic processing and whether the processing depends on the orientation of the objects--as it is in face processing. Children (6 to 11 years) and adults were instructed to classify upright and inverted objects (birds and planes) into two categories. The construction of the categories allowed participants to categorize the objects either analytically or holistically. The results showed a developmental trend from analytic to holistic processing, regardless of the objects' orientation. These findings indicate parallels as well as differences in the development of face and object processing.

Adult↗
PubMed1999

Learning categories by touch: on the development of holistic and analytic processing.

The development of holistic and analytic processing often studied in the visual domain was investigated in haptics. Children 3 to 9 years of age and adults had to categorize haptic exemplars that varied systematically in four attributes (size, shape, surface texture, and weight). The subjects could learn the categories either analytically--that is, by focusing on a single attribute--or holistically--that is, in terms of overall similarity. The data show that even the youngest children learned the haptic categories far more often in an analytic mode than in a holistic mode. Nevertheless, an age trend was observed, referring to the attributes that the analytic learners used for their categorization. The children preferred substance-related attributes, especially surface texture, whereas the adults preferred structure-related attributes, especially shape. Thus, it appears that analytic and/or holistic processing in category learning develops in a similar manner in the visual and haptic domains.

Adult↗
PubMed1997

Cisapride increases peak plasma and saliva ethanol levels under fasting conditions.

OBJECTIVES: Alcohol absorption is influenced by gastric first-pass metabolism through an alcohol dehydrogenase and the gastric emptying time. Whilst an influence of antisecretory drugs and aspirin on gastric alcohol metabolism has been described, the role of prokinetic drugs has not been determined. DESIGN: A randomized, placebo-controlled double-blind cross-over study was performed. SETTING: Out-patient facilities of a referral hospital. SUBJECTS: Eight male volunteers (age range 25-46 years). INTERVENTION: Treatment with two doses of either placebo or cisapride 150 micrograms/kg 7 h and 20 min before drinking 0.5 g/kg alcohol either in a fasting state or during a standardized meal (12 kcal/kg). MAIN OUTCOME MEASURES: Plasma and saliva ethanol concentrations were measured during 4 h. RESULTS: Cisapride increased peak plasma ethanol levels in fasting subjects from 15.6 (SD 1.4, 95%-KI 14.7;16.6) to 17.8 (SD 2.7, 95%-KI 15.9;19.7) mmol/L and saliva ethanol 30 min after alcohol ingestion from 11.4 (SD 2.2. 95%-KI 9.9;12.9) to 15.9 (SD 4.3, 95%-KI 12.9;18.8) mmol/L. A significant interaction between fasting state and drug intake was found for the 30 min saliva ethanol values (P < 0.05, ANOVA for repeated measurements). CONCLUSIONS: Cisapride may increase ethanol levels under fasting conditions. Patients treated with prokinetic drugs should be informed about this possibility.

Adult↗
PubMedDate not supplied

Development of face processing: the effect of face inversion.

The present experiment examined the degree to which analytic and holistic modes of processing play a role in the way children and adults categorize upright and inverted faces. Seven-year-old children (n = 38), 10-year-old children (n = 40), and adults (n = 55) were instructed to classify upright and inverted faces into two categories. The construction of the categories allowed participants to categorize the faces either analytically (by focusing on a single attribute) or holistically (in terms of overall similarity). The results show both a developmental trend from analytic to holistic processing and an effect of face inversion with increasing age. Thus, it appears that 7-year-old children process upright and inverted faces in a way comparable to their processing of nonfacial visual stimuli, namely analytically, whereas a growing proportion of 10-year-olds and adults process only upright faces holistically by adopting a specific mode of face processing.

Adult↗