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Biomedical subjects

K Schröder

Publications and source records attributed to K Schröder.

At least 19 recordsLinked to original sources
PubMed2005

Response of primary fibroblasts and osteoblasts to plasma treated polyetheretherketone (PEEK) surfaces.

Polyetheretherketone (PEEK) is a synthetic polymer with suitable biomechanical and stable chemical properties, which make it attractive for use as an endoprothetic material and for ligamentous replacement. However, chemical surface inertness does not account for a good interfacial biocompatibility, and PEEK requires a surface modification prior to its application in vivo. In the course of this experimental study we analyzed the influence of plasma treatment of PEEK surfaces on the cell proliferation and differentiation of primary fibroblasts and osteoblasts. Further we examined the possibility of inducing microstructured cell growth on a surface with plasma-induced chemical micropatterning. We were able to demonstrate that the surface treatment of PEEK with a low-temperature plasma has significant effects on the proliferation of fibroblasts. Depending on the surface treatment, the proliferation rate can either be stimulated or suppressed. The behavior of the osteoblasts was examined by evaluating differentiation parameters. By detection of alkaline phosphatase, collagen I, and mineralized extracellular matrix as parameters for osteoblastic differentiation, the examined materials showed results comparable to commercially available polymer cell culture materials such as tissue culture polystyrene (TCPS). Further microstructured cell growth was produced successfully on micropatterned PEEK foils, which could be a future tool for bioartificial systems applying the methods of tissue engineering. These results show that chemically inert materials such as PEEK may be modified specifically through the methods of plasma technology in order to improve biocompatibility.

Animals↗
PubMed2004

[Prediction of outcome in ST elevation myocardial infarction by the extent of ST segment deviation recovery. Which method is best?].

UNLABELLED: Simple and rapid measures are needed for timely assessment of the quality of reperfusion therapy early after fibrinolysis in acute STEMI. Sum ST segment elevation resolution (sum STR) categorized into the three groups of low risk (complete ST resolution), medium risk (partial ST resolution), and high risk (no ST resolution) has become an established method to predict infarct size, left ventricular function, epicardial vessel patency, and mortality. However, measurement of the sum of ST elevation from all leads of repeated ECG's is time-consuming. For routine practice more simple measures are needed. This report summarizes recent findings on direct comparisons between different modes of evaluation of ST segment deviation recovery employed for risk stratification in large-scale mortality trials. With respect to predictive accuracy combined with simplicity, two methods were superior to the conventional model of sum STR: 1) ST segment deviation resolution in only the one ECG lead showing the maximal deviation (single lead STR), and 2) the existing ST segment deviation in the single ECG lead of maximum deviation present 90 or 180 min after start of fibrinolysis (max STE). In multivariate analyses the ST segment deviation recovery models including sum STR were significant independent predictors of short- and long-term mortality. In receiver-operating characteristic (ROC) curves for predicting mortality the analysis of single lead STR and max STE performed better than sum STR. After categorization into risk groups patients are best classified by max STE. With an ECG recorded at 90 min in 2719 patients, the proportion of patients of sum STR, single lead STR, and max STE were 40, 34, and 43% in the low risk groups, and 24, 31, and 25% in the high risk groups. Cardiac mortality rates at 30 days were 2.0, 1.2, and 1.0% in low risk versus 9.6, 10.3, and 12.8% in the high risk groups, respectively. Long-term mortality with a followup of 5 years was best predicted by max STE risk groups. CONCLUSION: Single lead STR and max STE are very simple, inexpensive, non-invasive, and highly reliable measures which provide very strong early prognostic information. The relationship between degree of ST segment deviation recovery and subsequent mortality is remarkably consistent. Both methods perform better than sum STR in predicting mortality. They can be used for very early risk stratification and can form a basis for an individual treatment of patients after fibrinolysis for STEMI within 6 hours of symptom onset. Of the two methods max STE is even simpler to use and has better accuracy in predicting outcome.

Aged↗
PubMed2004

[Cyst of the common bile duct with acute abdomen].

Congenital cysts of the bile duct are well-documented anomalies of the biliary tree. Choledochal cysts frequently cause malignant changes in the epithelial lining. In such patients, the prognosis is very poor mainly because of the lack of typical symptoms in the early stages. The incidence of carcinoma in patients with bile duct cysts is estimated at 2.5 % to 15 %, compared to an incidence of 0.012 % to 0.48 % in patients without bile duct cysts. We report the case of a 32-year-old Vietnamese woman with a history of acute epigastric pain. Exploratory surgery was performed, and the segment containing the cyst and the ectopic pancreas was resected. Sonography pointed the way, and resection would have been necessary even without the abdominal symptoms.

Abdomen, Acute↗
PubMed2003

Tufted hair folliculitis associated with pemphigus vulgaris.

Tufted hair folliculitis (THF) is a rare disease which is characterized by the emergence of multiple hairs from widely dilated follicular orifices surrounded by an inflammatory infiltrate resulting in scarring alopecia. The pathogenesis is not yet fully understood. Although colonization with Staphylococcus aureus could not always be detected and systemic treatment with antibiotics alone is not sufficient, this microorganism is considered to play an important role. Around 30 patients with THF have been reported since the first publication. We present a patient with pemphigus vulgaris who developed THF. To our knowledge, this is the fourth case with an association of these two entities. Amongst other causing mechanisms, the autoimmune reaction may play an important role for the development of THF.

Administration, Topical↗
PubMed2001

Extent of ST-segment deviation in a single electrocardiogram lead 90 min after thrombolysis as a predictor of medium-term mortality in acute myocardial infarction.

BACKGROUND: In evolving myocardial infarction, assessment of the sum of early resolution of ST-segment elevation (sumSTR) has become an established method to predict outcome. We have found previously that mortality is predicted more accurately by the existing ST-segment deviation in the single electrocardiograph (ECG) lead with maximum deviation (maxSTE) 90 min after start of thrombolysis. This report compares the power to predict medium-term mortality by these two approaches. METHODS: An ST-segment resolution substudy was done in conjunction with the Intravenous nPA for Treatment of Infarcting Myocardium Early (InTIME) II Study, which compared mortality in patients with acute myocardial infarction randomly assigned lanoteplase or alteplase. In 2719 patients, a 12-lead ECG was assessed at baseline and 90 min after the start of thrombolytic therapy. FINDINGS: MaxSTE achieved a better combination of sensitivities and specificities for mortality prediction than sumSTR. The area under the receiver-operating characteristic curves for 180-day mortality prediction was 0.680 for maxSTE and 0.622 for sumSTR (difference 0.058; 95% CI 0.027-0.088). Risk groups categorised at low, medium, or high risk by maxSTE comprised 43%, 32%, and 24% of patients and those by complete, partial, or no sumSTR comprised 40%, 36%, and 24% of all patients. The 180-day mortality rates for the three maxSTE risk groups were 3.1%, 7.1%, and 16.2%, and those for the sumSTR groups were 4.8%, 8.1%, and 11.7%. The 12-month Kaplan-Meier estimates were 4.1%, 8.8%, and 18.6%, and 5.9%, 9.9%, and 13.7%, respectively. INTERPRETATION: MaxSTE predicts early and medium-term mortality more accurately than does sumSTR. The prognosis for an individual patient can be accurately estimated simply by the ST-segment deviation present in one ECG lead recorded 90 min after thrombolysis.

Electrocardiography↗
PubMed2001

Rapid decline of antibodies after hepatitis A immunization in liver and renal transplant recipients.

BACKGROUND: Hepatitis A vaccine is safe and achieves good seroconversion rates in liver (LTX) and renal (RTX) transplant recipients. METHODS: A study was performed to determine the anti-hepatitis A virus (HAV) antibody decline in LTX and RTX patients, and in healthy controls who have been immunized with two doses of hepatitis A vaccine. RESULTS: LTX and RTX patients had a satisfactory seroconversion rate after complete immunisation. However, 2 years later they had experienced a much more rapid antibody decline than controls, and only 59% of LTX and 26% of RTX seroconverters showed titres above the cut-off level defined as protective. CONCLUSIONS: Patients on immunosuppressive therapy may not be adequately protected against hepatitis A a few years after vaccination and alternative vaccination schemes may have to be considered.

Cyclosporine↗
PubMed2001

Extent of ST-segment deviation in the single ECG lead of maximum deviation present 90 or 180 minutes after start of thrombolytic therapy best predicts outcome in acute myocardial infarction.

UNLABELLED: In evolving myocardial infarction the extent of ST segment deviation reflects the existing ischemic myocardial injury and thus conveys very useful early prognostic information. In recent years, the sum of ST segment elevation resolution (sum STR) has been proven to be an excellent early prognostic indicator. However, the predictive power of sum STR has never been systematically compared with that of other methods of evaluation of ST segment deviation recovery. We, therefore, proposed to compare the prognostic power of ST segment changes evaluated by either sum STR or by ST segment resolution in only the one lead showing the maximal deviation (lead STR) or only by the existing ST segment deviation in the single ECG lead of maximum ST deviation present at a given time point after thrombolysis (lead STE). METHODS AND RESULTS: In conjunction with the Intravenous nPA for Treatment of Infarcting Myocardium Early (InTIME) II Study, which compared mortality in patients with acute myocardial infarction randomized within 6 hours of symptom onset to receive either Lanoteplase or Alteplase, all 3593 German and Polish patients participated in an ST segment resolution substudy. A 12-lead ECG was recorded at baseline and at 90 and at 180 minutes after start of thrombolytic therapy. The areas under the receiver-operating characteristic (ROC) curves to compare the power to predict 30 day cardiac mortality for sum STR, lead STR, and lead STE were at 90 min 0.686, 0.714, and 0.761 (p < 0.002), and at 180 min 0.678, 0.703, and 0.755 (p < 0.001), respectively. In multivariate analysis lead STE was an independent predictor of outcome even when adjustment was made for sum STR, lead STR, and clinical variables. Cardiac mortality rates at 30 days for lead STE risk groups, classified as low, medium, or high (percent of patients in brackets), were at 90 min 1.0% (43%), 4.0% (32%), and 12.8% (25%), and at 180 min 1.5% (55%), 3.8% (31%), and 15.2% (14%), respectively. CONCLUSIONS: Simple measurement of the ST segment deviation existing in the one ECG lead with the greatest deviation on the ECG recorded 90 or 180 minutes after thrombolysis enables the identification of the major subsets of patients who are either at very low or exceptionally high risk of mortality.

Adult↗
PubMed2001

Comparative genomic hybridization analysis of chromosomal alterations in patients with long-standing ulcerative colitis.

Patients with ulcerative colitis (UC) are prone to develop colorectal cancer which is related to the duration and extent of the disease. One of the earliest events in tumor progression is the development of aneuploidy. Aneuploidy is correlated with the grade of dysplasia which serves as a common but not always reproducible marker for the prediction of UC associated formation of cancer. We analyzed 48 biopsy samples from 5 patients with long-standing ulcerative colitis by comparative genomic hybridization (CGH). The majority of these samples represented premalignant stages which are not well characterized at the molecular level as yet. We compared biopsy samples from different colon locations in regard to chromosomal alterations, dysplasia status and DNA index. Besides chromosomal changes occurring only in certain patients in restricted areas of the colon we also detected amplifications and deletions which were common in all persons throughout the colon. The stage of dysplasia seems to have no influence on the number and appearance of chromosomal changes. Amplifications in 2, 3, 6, 9, 11, 12 and 15 were found in almost all cases. In dysplastic samples chromosomal regions 3, 6 and 11 revealed gains of DNA. Deletions were detected within 8q, 15, 18q, 20p and 22q. The affected chromosomal regions may contain yet unknown oncogenes or tumor suppressor genes participating in UC associated carcinogenesis. The conspicuous regions found in the CGH experiments allow the selective and detailed characterization at a molecular level.

Chromosome Aberrations↗
PubMed2000

[Expectations and attitudes of medical students concerning work stress and consequences of their future medical profession].

In the following cross-sectional study 245 medical students from two different terms (three years apart) were being questioned about work stress and the consequences of their future medical profession. Attitudes and expectations regarding future work stress, work satisfaction, coping strategies, gender specific problems, effects on private life and future quality of life were studied. As expected, students in the upper term were able to judge their professional and private future more realistically. The expectations of the advanced students are more realistic and as a consequence it is likely that a disillusioning process is taking place. The results contribute to a better understanding of the present study situation and well-being of medical students concerning their professional and private future which is also important for teaching and the teaching professionals.

Adult↗
PubMed2000

Transcranial Doppler ultrasonography as a screening technique for detection of a patent foramen ovale before surgery in the sitting position.

BACKGROUND: Venous air embolism has been reported to occur in 23-45% of patients undergoing neurosurgical procedures in the sitting position. If venous air embolism occurs, a patent foramen ovale (PFO) is a risk factor for paradoxical air embolism and its sequelae. Preoperative screening for a PFO is therefore recommended by some investigators. The reference standard for identifying a PFO is contrast-enhanced transesophageal echocardiography (c-TEE). Contrast-enhanced transcranial Doppler ultrasonography (c-TCD) and contrast-enhanced transthoracic echocardiography (c-TTE) are noninvasive alternative methods, but so far there are no studies as to their diagnostic validity in neurosurgical patients. METHODS: The sensitivity and specificity of c-TCD and c-TTE in detecting a PFO were determined in a prospective study using c-TEE as the reference standard. Preoperative c-TCD, c-TTE, and c-TEE studies were performed during the Valsalva maneuver after intravenous echo-contrast medium (D-Galactose, Echovist-300, Schering AG, Berlin, Germany) was administered in 92 consecutive candidates (47 men and 45 women; mean age, 51 yr; range, 25-72 yr) before neurosurgical procedures in the sitting position. RESULTS: A PFO was detected in 24 of the 92 patients (26.0%) using c-TEE. c-TCD correctly identified 22 patients, whereas c-TTE only correctly identified 10. This corresponds to a sensitivity of 0.92 for c-TCD and 0.42 for c-TTE. The negative predictive value was 0.97 for c-TCD compared with 0.83 for c-TTE. The prevalence of a PFO in patients with a posterior fossa lesion was 27%, and in the group with cervical disc herniation was 24% as detected by c-TEE. The incidence of intraoperative venous air embolism was 35% in cases of cervical foraminotomy and 75% in posterior fossa surgery as detected by c-TEE. CONCLUSIONS: c-TCD is a highly sensitive and highly specific method for detecting a PFO. Because c-TCD is noninvasive, it may be more suitable than c-TEE for routine preoperative screening for a PFO. C-TTE is not reliable in detecting a PFO.

Adult↗
PubMed1999

Control of glycosylation of MHC class II-associated invariant chain by translocon-associated RAMP4.

Protein translocation across the membrane of the endoplasmic reticulum (ER) proceeds through a proteinaceous translocation machinery, the translocon. To identify components that may regulate translocation by interacting with nascent polypeptides in the translocon, we used site-specific photo-crosslinking. We found that a region C-terminal of the two N-glycosylation sites of the MHC class II-associated invariant chain (Ii) interacts specifically with the ribosome-associated membrane protein 4 (RAMP4). RAMP4 is a small, tail-anchored protein of 66 amino acid residues that is homologous to the yeast YSY6 protein. YSY6 suppresses a secretion defect of a secY mutant in Escherichia coli. The interaction of RAMP4 with Ii occurred when nascent Ii chains reached a length of 170 amino acid residues and persisted until Ii chain completion, suggesting translocational pausing. Site-directed mutagenesis revealed that the region of Ii interacting with RAMP4 contains essential hydrophobic amino acid residues. Exchange of these residues for serines led to a reduced interaction with RAMP4 and inefficient N-glycosylation. We propose that RAMP4 controls modification of Ii and possibly also of other secretory and membrane proteins containing specific RAMP4-interacting sequences. Efficient or variable glycosylation of Ii may contribute to its capacity to modulate antigen presentation by MHC class II molecules.

Amino Acid Sequence↗
PubMed1999

Chemical micropatterning of polymeric cell culture substrates using low-pressure hydrogen gas discharge plasmas.

Micropatterned cell cultures will allow a new quality of bioartificial systems. Here, an approach to chemical micropatterning of polymer substrates is presented, which is completely based on low pressure gas discharge processes. Well expressed micropatterned cell cultures on polystyrene and poly (ether ether ketone) were obtained with many different cell types. No impairment of typical cell behavior was observed.

Journal Article↗
PubMed1999

Immunogenicity and safety of hepatitis A vaccine in liver and renal transplant recipients.

Organ transplant recipients with chronic hepatitis B or hepatitis C virus infection may be at increased risk of fulminant hepatitis A. Liver transplant (LTX) recipients, renal transplant (RTX) recipients, and healthy controls received 2 doses of hepatitis A vaccine 6 months apart. Anti-hepatitis A virus (anti-HAV) seroconversion after the primary dose occurred in 41% of the LTX patients, 24% of the RTX patients, and 90% of the controls. After the booster dose, the respective rates were 97%, 72%, and 100% (P<.001). RTX patients also had significantly lower geometric mean titers (GMTs) of anti-HAV than LTX patients and controls. In the RTX group, the seroconversion rate and GMT were inversely associated with the number of immunosuppressive drugs received by the patients. The vaccine was well tolerated. Hepatitis A vaccine can be recommended to LTX and RTX patients, but the patients should receive a full course of 2 doses before imminent exposure.

Adult↗
PubMed1998

[Zosteriform lichen aureus].

Lichen aureus is a special localized variant of purpura pigmentosa chronica. A patient presented with an unusual striate and segmental or zosteriform distribution of lichen aureus involving the left leg and lower abdominal area. Histology showed the characteristic dense band-like infiltrate consisting mainly of small lymphocytes and numerous hemosiderin-containing macrophages. No underlying infection or medication could be identified as a trigger. The lesions did not respond well to topical corticosteroid therapy.

Biopsy↗
PubMed1998

[Effect of cardiac embolism sources on origin of territorial cerebral infarcts].

BACKGROUND AND PURPOSE: To test the association of cardiac sources of embolism with territorial type brain infarcts. METHODS: From a prospective cerebral ischemia data base the 106 consecutive patients with territorial type cerebral infarcts on computerized tomography were analyzed. The 85 consecutive patients with lacunar lesions served as a comparison group. The association of cardiac sources of embolism with territorial types infarcts was assessed using univariate Chi Square tests and logistic regression models. Cardiac sources of embolism were defined as:atrial fibrillation, left cardiac thrombi, valvular vegetations, wall motion and valvular abnormalities, left atrial enlargement, open foramen ovale, septal aneurysm, mitral valve prolaps, and aortic arch atherothrombosis (all findings--except for atrial fibrillation--assessed by echocardiography). RESULTS: Atrial fibrillation was significantly associated with territorial type infarcts (odds ratio 2.2, 95% confidence interval 1.01-4.8). This effect was independent of additional cardiac diseases, other cardiac abnormalities, carotid artery stenosis, and patient age. Most likely due to the small sample size, left cardiac thrombi only showed a non-significant trend towards an association with territorial infarcts (odds ratio 3.0, 95% confidence interval 0.7-12.3). The rate of all other cardiac findings did not differ significantly between the comparison groups. CONCLUSION: Atrial fibrillation and cardiac thrombi showed an association with territorial type infarcts. Other so-called cardiac sources of embolism--except for mechanical valves and bacterial endocarditis which were not represented in our sample--revealed no clinically relevant association with embolic brain infarct pattern.

Adult↗
PubMed1998

Deletion mapping by FISH with BACs in patients with partial monosomy 22q13.

Patients with deletions in 22q13 are known to have phenotypic features that include normal or accelerated growth, large hands and feet, hypotonia, delayed psychomotor development and mild facial dysmorphism. To date, very few cases have been investigated by detailed molecular genetic analysis. We have analyzed three new patients with terminal deletions in 22q. We compared the cytogenetic observations with molecular data assessed by fluorescence in situ hybridization and an array of characterized bacterial artificial chromosome recombinants. The shortest region of deletion overlap is localized in 22q13.2-qter distal to the marker D22S94, but the telomeric repeat in the deleted chromosome appears to remain intact. When parental alleles were investigated in two of the three patients, the aberrant homolog was found to be of paternal origin in both cases. Although the deleted region still spans >20 cM, molecular analysis of additional patients and screening for new genes might help in elucidating candidate genes connected with the dysmorphisms defined by deletions of 22q13.

Child, Preschool↗