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Biomedical subjects

B Meyer

Publications and source records attributed to B Meyer.

At least 19 recordsLinked to original sources
PubMed2006

Persistently high levels of immunosuppressive cytokines in patients after radical prostatectomy.

A significant proportion of men undergoing 'curative' radical prostatectomy (RP) for organ-confined prostate cancer relapse within 5 years. A number of adverse risk factors have been identified, but to date no adjuvant treatment as improved the outlook for these men. We proposed that these patients, despite small tumour burdens, may be immunosuppressed from their cancer, which may be amenable to immune modulation. We investigated their immune profile using sensitive functional cytokine assays, both pre- and post-surgery. In comparison with controls, RP patients expressed higher levels of both T helper type 1 (Th1) (interleukin (IL)-2 and tumour necrosis factor-alpha) and Th2 cytokines (IL-4, -5 and -10) with little change after removal of tumour. Further analysis based on known poor-prognostic factors indicated a trend to expression of higher levels of Th2 cytokines IL-4 and IL-5 in worse prognosis patients rather than the mixed Th1/2 found across the whole cohort. Persistently high levels of both Th1 and Th2 cytokines were detected in RP compared to control patients, despite the removal of relatively small tumour burdens. Cytokine expression studies may be useful as surrogate marker of potential disease progression, and could be used to identify patients who may benefit from immune modulation post-surgery.

Aged↗
PubMed2006

Structure and dynamics of CO overlayers on a hydroxylated metal oxide: the polar ZnO(0001) surface.

The adsorption and desorption of CO on the hydroxylated, O-terminated polar ZnO(0001) surface has been studied using He-atom scattering. The experimental results reveal the formation of a physisorbed ordered CO overlayer. In addition to recording angular distributions of elastically scattered He atoms, also the dynamical properties of the CO overlayer have been investigated using inelastic He-atom scattering. With the aid of electronic structure calculations a loss peak with an energy transfer of 7.2 meV is assigned to the frustrated translation of the CO molecule normal to the surface.

Journal Article↗
PubMed2006

The advantages and disadvantages of nerve monitoring during thyroid surgery in childhood.

BACKGROUND: Intraoperative damage of the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN) are common and cause complications in thyroid surgery. The method of intraoperative electrophysiological neuromonitoring (IONM) of the RLN and the EBSLN has been used in adults for several years. The question is whether IONM can be used in paediatric surgery for the identification and functional control of the RLN and the EBSLN, and what the advantages and disadvantages of using it are. METHODS: Surgical treatment of benign (n = 9) and malign (n = 2) thyroid diseases was carried out in eleven children (median age: 13 years) with a total of 18 nerves at risk (NAR). The function of the vocal cord was monitored in all children before and after surgery. Intraoperative identification and functional control of RLN and EBSLN was performed using the Neurosign 100. All results before and after resection of the thyroid gland were documented. RESULTS: A clear and reliable identification of the RLN and the EBSLN was possible in all cases. All NAR showed a constant physiological nerve signal before and after surgical resection of the thyroid gland. However, in one young patient the postoperative examination of the vocal cord revealed a partial paralysis on the left side after thyroidectomy, despite the constant intraoperative signal of the RLN. After a period of six months, normal functioning had resumed. CONCLUSION: The IONM of both RLN and EBSLN in adult surgery could be used successfully in paediatric surgery. In this study a clear and positive identification of both nerves was possible in all patients. Therefore the IONM of the RLN and EBSLN could develop into a successful and easy method for the prevention of intraoperative nerve damage during thyroid surgery in childhood and young adolescence. Assuming that a constant IONM signal represents a normal vocal cord, our evaluation showed that there is a small percentage of false negative and positive results.

Adolescent↗
PubMed2006

Rb-loss is associated with high malignancy in chondrosarcoma.

Loss of function of the human retinoblastoma gene (Rb) is a frequent genetic abnormality in human malignancies and causes a disturbance in the cell cycle and loss of normal proliferation and differentiation. We studied the loss of heterozygosity (LOH) of the Rb gene in 31 formalin-fixed, paraffin-embedded cartilaginous tumors using polymerase chain reaction. The tumors were subdivided into 8 cases of dedifferentiated (DD) chondrosarcoma, 17 cases of conventional chondrosarcoma (nine grade 1, seven grade 2 and one grade 3), 4 enchondromas and 2 chondroblastomas. Both components of DD chondrosarcoma, the low-grade and anaplastic components, were separated by a microdissection approach. The genetic data were correlated with the expression of the Rb protein examined by Rb immunohistochemistry. We found Rb-LOH in one grade 3 chondrosarcoma, and in the anaplastic component in 7 of 8 cases of DD chondrosarcoma (89% of all high-grade chondrosarcomas). All tumors with Rb-LOH were immunohistochemically Rb-negative. The only case of DD chondrosarcoma negative for Rb-LOH in both components of the tumor also showed weak expression of the Rb protein in the anaplastic component. All benign cartilaginous tumors, low-grade chondrosarcomas and low-grade tumor components of DD chondrosarcomas were negative regarding Rb-LOH but positive in Rb immunohistostaining. We concluded that Rb-LOH predominantly occurs in high-grade chondrosarcomas. However, it is not a marker for identifying low-grade tumors with a tendency towards progression or local recurrence.

Adolescent↗
PubMed2005

Hydrogen induced metallicity on the ZnO(1010) surface.

Exposure of the mixed-terminated surface to atomic hydrogen at room temperature is found to lead to drastic changes of the electrical properties. The insulator surface is found to become metallic. By employing several experimental techniques (electron energy loss spectroscopy, He-atom scattering, and scanning tunneling microscopy) together with ab initio electronic structure calculations we demonstrate that a low-temperature (1 x 1) phase with two H atoms in the unit cell transforms upon heating to another (1 x 1) phase with only one H atom per unit cell. The odd number of electrons added to the surface per unit cell gives rise to partially filled surface states and thus a metallization of the surface.

Journal Article↗
PubMed2005

"Best friends" sharing the HMGA1 gene: comparison of the human and canine HMGA1 to orthologous other species.

HMGA1 nonhistone proteins are reported to participate in various cellular processes including regulation of inducible gene transcription, integration of retroviruses into chromosomes, and the induction of neoplastic transformation and promotion of metastatic progression of cancer cells. Overexpression of HMGA1 was shown to be characteristic for various malignant tumors, suggesting a relation between the neoplastic phenotype and a high titer of the protein. Also chromosomal aberrations affecting the human HMGA1 gene at 6p21 were described in several tumors, e.g., uterine leiomyomas, pulmonary chondroid hamartomas, and follicular thyroid adenomas. We characterize the molecular structure of the canine HMGA1 cDNA, its splice variants, and predicted proteins HMGA1a and HMGA1b. Furthermore, we compared the CDS of both splice variants for 12 different breeds, screened them for SNPs, characterised a basic expression pattern, and mapped the gene via FISH. Additionally, we compared the known human, canine, murine, rat, hamster, bovine, pig, Xenopus, and chicken HMGA1 transcripts.

Animals↗
PubMed2005

Intermittent administration of betalactam-antibiotics for treatment of severe infection in hemodialysis patients.

Infections are a leading cause of morbidity and mortality in hemodialysis patients. Still, due to altered pharmacokinetics and potential toxic sideeffects, safe and efficient antibiotic therapy in dialysis patients remains a major challenge. We reviewed our experience with intermittent administration of betalactam antibiotics for treatment of severe infections in hemodialysis patients. A total of 81 episodes of infection in 45 patients was assessed. All patients were treated with betalactam antibiotics (cefepime in 11 episodes, cefpirom in 33 episodes, piperacillin in 9 episodes, amoxicillin in 18 episodes, ceftazidime in 10 episodes, respectively). All antibiotics were given post hemodialysis 3x per week. Treatment was considered efficient in case of a significant decrease in CRP in addition to clinical response. Overall treatment success rate was 85% (69 episodes of infection). The decrease of CRP was 52% (6.9 +/- 5.8 to 3.3 +/- 4.9 mg/dl; p = 0.00003). The mean duration of treatment was 19 +/- 13 days. Treatment was generally well tolerated. We conclude, that severe infections in hemodialysis patients can be treated safely and efficiently with an empiric therapy with betalactam antibiotics. Intermittent administration, potentially allowing ambulatory treatment, is possible.

Amoxicillin↗
PubMed2004

Refinement of the DFNA4 locus to a 1.44 Mb region in 19q13.33.

Many forms of autosomal dominant non-syndromic hearing impairment are known. While the underlying gene defects and causative mutations have been discovered for some forms, the gene responsible for DFNA4 has remained elusive to date. Examination of a German four-generation kindred led to the identification of a 1.44 Mb map segment in contig NT_011109 as being the most likely DFNA4 candidate region in 19q13.33. The recombination breakpoints in this family and the intervals of two previously reported DFNA4 families allowed us to delineate a minimum consensus region between the markers D19S879 and D19S246. In our family, a maximum two-point LOD score of 4.5 was obtained at theta = 0 for the marker D19S867. Within the refined DFNA4 interval the public databases list more than 50 genes, from which several appear to be promising DFNA4 candidates due to similarities with animal models and with other causative genes involved in hearing disability.

Adult↗
PubMed2004

Acute epiglottitis: MRI.

We report the MRI findings in an adult with epiglottitis. There was thickening of the epiglottis and left aryepiglottic fold. Management of this life-threatening condition requires imaging only when the diagnosis is uncertain or when an abscess or other complication is suspected.

Abscess↗
PubMed2004

Immediate postoperative angiography after aneurysm clipping--implications for quality control and guidance of further management.

BACKGROUND: To determine the impact of postoperative angiography after aneurysm clipping on quality control and further management. METHODS: A recent consecutive series of n = 296 patients (186 females, 110 males, mean age 51 yrs) who underwent 324 craniotomies to clip 384 aneurysms was reviewed. New irregularities on postoperative angiographies were categorized as unrelated (e. g. vasospasm) or related (= vessel occlusion/residuum) to clipping and expected or unexpected by the surgeon. Therapies prompted by these findings as well as subsequent negative sequelae were analyzed. Factors related to negative events were identified by logistic regression (p < 0.05). RESULTS: Twenty-six (8%) unrelated findings prompted medical or intravascular therapy. Of 36 (9.4%) clip-related findings (n = 17 occlusions, n = 19 residua), 14 (3.6%) were unexpected (n = 9 occlusions, n = 5 residua). This was followed by 9 (2.3%, n = 4 occlusions, n = 5 residua) clip readjustments and 6 aggressive medical therapies. Nine patients were scheduled for angiographic follow-up, of which in five performed so far no change of aneurysm remnants was noted. Permanent sequelae from vessel occlusion occurred in 9 cases. Major premature rupture (p < 0.005), giant size/fusiform configuration (p < 0.001), posterior circulation aneurysms (p < 0.05) and ophthalmic segment location (p < 0.008) were significantly related to adverse postoperative findings. The use of microvascular Doppler significantly reduced the rate of unexpected vessel occlusion (3.3 vs. 0.9%). CONCLUSIONS: Apart from the need for quality control in aneurysm clipping--especially with respect to coiling--our results stress the importance of postoperative angiography, because a small, but significant subset of patients will benefit from immediate intervention and/or deserves long-term follow-up.

Angiography↗
PubMed2004

Planar brain surface reformations for localization of cortical brain lesions.

Cortical lesions close to the central region may be difficult to localize on orthogonal MRI slices, especially when space-occupying lesions distort the brain surface relief and obscure anatomical landmarks. The purpose of this study was to evaluate, whether localization can be improved with planar brain surface (Mercator or "pancake") reformations. Three independent MRI readers localized superficial brain lesions of 30 patients on orthogonal MRI slices and on planar brain surface views reformatted from a sagittal 3D T(1)-weighted gradient echo sequence. On orthogonal MRI slices 46% of lesions were considered easy to localize, 37% difficult and 17% could not be localized. Corresponding values for planar brain surface views were 82%, 16% and 2%, respectively. Evaluation of orthogonal MRI slices took 190 min compared to 100 min for planar brain surface views. Thus, planar brain surface reformations are a helpful and time-saving means to localize superficial brain lesions.

Adolescent↗
PubMed2004

Comparative prevalence of sensitization to common animal, plant and mould allergens in subjects with asthma, or atopic dermatitis and/or allergic rhinitis living in a tropical environment.

BACKGROUND AND OBJECTIVES: Current information suggests that the expression of allergic diseases is determined by the exposure and nature of the allergen. The objectives of the present study were to determine if the nature of allergenic exposition to animal, plant or fungal allergens influenced the clinical manifestations of atopic dermatitis (AD), allergic rhinitis (AR) or asthma (AS) in patients living in a tropical environment. The prevalence and degree of sensitization to these allergens were analysed by age and gender. SUBJECTS AND METHODS: A total of 1496 atopic cases, grouped according to the primary diagnosis of AD or AR or AS, were skin tested using a standardized allergen panel. Participants were categorized by age groups. The atopic index (AI) and mean weal diameter (MWD) as well as the prevalence of positive skin tests were determined for each of the patient groups and compared by age groups. RESULTS: The prevalence of atopy as well as the AI and the MWD peaked at 6-15 years of age and declined thereafter. In all the patients tested, the prevalence of sensitization was, in decreasing order; dust mites 94.3%, cockroach 41.5%, pets 31.5%, plant allergens 31.1% and fungal 19.4%. Eight hundred and ninety-three atopic patients were exclusively sensitized only to animal allergens. Of these, 38.4% had AD, 31.3% had AR and 30.5% with AS. CONCLUSION: These data demonstrate that for patients with AD, AR and AS living in a tropical environment, the prevalence of positive skin reactions to animal allergens is highest followed by plant and fungal allergens. We did not observe any association between the type of allergen and clinical manifestations. The index of atopy was similar for both sexes. The prevalence and degree of sensitization were shown to peak in young adults independent of the allergen in AD and AR patients.

Adolescent↗
PubMed2004

Pharmacokinetics of teicoplanin during continuous hemofiltration with a new and a 24-h used highly permeable membrane: rationale for therapeutic drug monitoring-guided dosage.

OBJECTIVE: Continuous venovenous hemofiltration (CVVH) is widely used in the management of critically ill patients, but only few administration guidelines for antimicrobial drugs are available. It is unclear whether the use of a filter for more than 24 hours might lead to less efficient extraction. This study describes the pharmacokinetics of teicoplanin during CVVH using a highly permeable membrane. METHODS: Pharmacokinetics of teicoplanin during continuous hemofiltration with a new (group 1) and a 24-h used (group 2), highly permeable polyamide membrane were assessed in 3 patients. RESULTS: The teicoplanin serum concentrations (44.0 +/- 18.5 mg/l vs 109.5 +/- 34.5 mg/l) and half-life of teicoplanin (4.6 +/- 1.1 h vs 5.2 +/- 0.7 h) differed significantly between the 2 groups indicating a smaller elimination of the drug on the second day. Substantial binding of teicoplanin to filter membranes could explain this observation. CONCLUSION: The results suggest that daily adjustment of the dosage is necessary to achieve sufficient teicoplanin concentrations and a fixed dosage recommendation is not suitable for this drug.

Anti-Bacterial Agents↗
PubMed2003

Stabilization of polar ZnO surfaces: validating microscopic models by using CO as a probe molecule.

The determination of the structure of inhomogeneous metal-oxide surfaces represents a formidable task. With the present study, we demonstrate that using the binding energy of a probe molecule, CO, is a reliable tool to validate structural models for such complex surfaces. Combining several types of first-principles calculations with advanced molecular beam methods, we are able to provide conclusive evidence that the polar O-terminated surface of ZnO is either reconstructed or hydrogen covered. This finding has important consequences for the ongoing discussion regarding the stabilization mechanism of the electrostatically unstable ("Tasker type 3") polar ZnO surfaces.

Journal Article↗