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Biomedical subjects

T Meyer

Publications and source records attributed to T Meyer.

At least 37 records · Page 2Linked to original sources
PubMed2006

Cardiocirculatory and metabolic responses at different walking intensities.

OBJECTIVES: Although walking is a common physical activity, scientifically based training guidelines using standardised tests have not been established. Therefore this explorative study investigated the cardiovascular and metabolic load resulting from different walking intensities derived from maximal velocity (Vmax) during an incremental treadmill walking test. METHODS: Oxygen uptake, heart rate (HR), blood concentrations of lactate and catecholamines, and rating of perceived exertion were recorded in 16 recreational athletes (mean (SD) age 53 (9) years) during three 30 minute walking trials at 70%, 80%, and 90% of Vmax (V70, V80, and V90) attained during an incremental treadmill walking test. RESULTS: Mean (SD) oxygen uptake was 18.2 (2.3), 22.3 (3.1), and 29.3 (5.0) ml/min/kg at V70, V80, and V90 respectively (p<0.001). V70 led to a mean HR of 110 (9) beats/min (66% HRmax), V80 to 124 (9) beats/min (75% HRmax), and V90 to 152 (13) beats/min (93% HRmax) (p<0.001). Mean (SD) lactate concentrations were 1.1 (0.2), 1.8 (0.6), and 3.9 (2.0) mmol/l at V70, V80, and V90 respectively (p<0.001). There were no significant differences between catecholamine concentrations at the different intensities. Rating of perceived exertion was 10 (2) at V70, 12 (2) at V80, and 15 (2) at V90. Twelve subjects reported muscular complaints during exercise at V90 but not at V70 and V80. CONCLUSIONS: Intensity and heart rate prescriptions for walking training can be derived from an incremental treadmill walking test. The cardiovascular and metabolic reactions observed suggest that V80 is the most efficient workload for training in recreational athletes. Further studies are needed to confirm these findings.

Energy Metabolism↗
PubMed2006

Inhaled beta2 agonists and performance in competitive athletes.

OBJECTIVES: To provide an overview of the current literature on the use of inhaled beta2 agonists in non-asthmatic competitive athletes, and to assess the performance enhancing effect of inhaled beta2 agonists. METHODS: Review of the literature. RESULTS: Twenty randomised, placebo controlled studies (19 double blind, one single blind) were located. Only three studies reported a performance enhancing effect of inhaled beta2 agonists. However, methodological shortcomings were most likely responsible for these findings (for example, non-elite athletes, inconsistent results in different tests, subgroups with above-average responsiveness). CONCLUSIONS: This review reveals that there is no ergogenic potential of inhaled beta2 agonists in non-asthmatic athletes. In view of the epidemiology of asthma in athletes and the considerable workload involved in provision of therapeutic use exemptions the inclusion of inhaled beta2 agonists on the list of prohibited substances should be reconsidered.

Administration, Inhalation↗
PubMed2006

Lymphogranuloma venereum emerging in men who have sex with men in Germany.

A resurgence of lymphogranuloma venereum (LGV) has been observed in several European countries. LGV is not a mandatorily notifiable disease in Germany. Reports of LGV cases have actively been collected by the Robert Koch-Institut since 2004 to describe the outbreak and estimate the extent of the LGV problem in Germany. Updates on the LGV outbreak were published in the German national epidemiological bulletin. Physicians were asked to send their samples to a laboratory for genotyping. A possible case was defined as a person with symptoms of proctitis and/or inguinal lymph node swelling and a positive chlamydia serology. A probable case had in addition a positive chlamydia rectal or urinary PCR test. A case was confirmed if the genotype L1-L3 was identified based on sequence analysis of omp1 gene sequences. Since 2003, LGV has been reported in 78 male patients in Germany. Of these, 61 patients were confirmed as genotype L2. Fifty eight out of 78 patients (74%) are known to be men who have sex with men (MSM). Fifty five patients (71%) had rectal symptoms and 49 (63%) knew they were HIV positive. Sixty two (79%) of the patients were residents of Berlin or Hamburg. LGV has emerged in MSM in Germany at the same time as in other European countries. It is thought that LGV may become endemic in the MSM community in German metropolitan areas, because the number of reported patients with LGV continues to increase. The increase in the number of LGV cases and the high HIV prevalence in LGV patients are of great public health concern. Clinicians and MSM may not be sufficiently aware of the disease, and existing efforts to promote awareness and prevention of sexually transmitted infections and HIV need to be strengthened.

Disease Outbreaks↗
PubMed2005

Hyperthermic isolated limb perfusion (HILP) in malignant melanoma. Experience with 101 patients.

AIMS: To analyse results with a standardized HILP procedure in terms of response rate, recurrence pattern and complication rate. PATIENTS AND METHODS: From 1992 to 2003 HILP with melphalan and dactinomycin was performed in 101 patients with loco-regional metastases of malignant melanoma of the limbs. Among these were 66 women and 35 men with a median age of 62 years. Forty patients were in M. D. Anderson stage IIIA, 51 patients in stage IIIAB and 9 had stage IV disease at the time of perfusion. If not been done before, regional lymph node dissection preceded limb perfusion in the same setting. RESULTS: A complete response (CR) was observed in 58 out of 87 evaluable patients. Twenty-one patients achieved a partial response (PR) and eight patients were non-responders. The overall response rate was 90.8%. The median recurrence-free interval after CR was 21 months. Severe toxicity (Wieberdink IV/V) was observed in five patients necessitating fasciotomy in four of them and above knee amputation in one patient. All further cases presented with grade II-III toxicity. The overall survival was 42 months, with a 5-year survival rate of 38%. Survival significantly differed according to stage of disease. CONCLUSION: HILP is an effective treatment for loco-regional tumour relapse of malignant melanoma of the extremities and has improved by modification of technique. In the absence of regional lymph node and distant metastases long-term survival can be achieved in responders.

Adult↗
PubMed2005

Early-onset ALS with long-term survival associated with spastin gene mutation.

The authors report a 73-year-old patient with a natural history of early-onset ALS for 49 years presenting with limb and bulbar amyotrophy and a pyramidal syndrome. Analysis of the locus SPG4 identified a heterozygous duplication mutation (c.304_309dupGCCTCG) within exon 1 of the spastin gene. We propose that sequence alterations of spastin may comprise a genetic risk factor in a greater spectrum of motor neuron disorders including clinical variants of ALS.

Adenosine Triphosphatases↗
PubMed2005

Efficient chromosome capture requires a bias in the 'search-and-capture' process during mitotic-spindle assembly.

The mitotic spindle assembles into a bipolar, microtubule-based protein machine during prometaphase. One proposed mechanism for this process is "search-and-capture," in which dynamically unstable microtubules (MTs) search space to capture chromosomes. Although existing theoretical estimates suggest that dynamic instability is efficient enough to allow capture within characteristic mitotic timescales, they are limited in scope and do not address the capture times for realistic numbers of chromosomes. Here we used mathematical modeling to explore this issue. We show that without any bias toward the chromosomes, search-and-capture is not efficient enough to explain the typical observed duration of prometaphase. We further analyze search-and-capture in the presence of a spatial gradient of a stabilizing factor that biases MT dynamics toward the chromosomes. We show theoretically that such biased search-and-capture is efficient enough to account for chromosome capture. We also show that additional factors must contribute to accelerate the spindle assembly for cells with large nuclear volumes. We discuss the possibility that a RanGTP gradient introduces a spatial bias into microtubule dynamics and thus improves the efficiency of search-and-capture as a mechanism for spindle assembly.

Chromosomes, Human↗
PubMed2005

Deuterium NMR investigation of the biaxial nematic phase in an organosiloxane tetrapode.

Deuterium NMR is used to examine the molecular order exhibited by an organosiloxane tetrapode giving the first experimental evidence, using a bulk sample, for the existence of a biaxial nematic phase in this type of compounds. The temperature dependence of the averaged quadrupolar coupling constant and asymmetry parameter was determined in the compound's nematic phase. Two distinct regimes could be identified, one with a vanishing asymmetry parameter corresponding to a uniaxial nematic phase and another with a significant temperature dependent asymmetry parameter, corresponding to a biaxial nematic phase. The high values obtained for the asymmetry parameter at the lower end of the nematic range are well above experimental error and constitute a definite proof of the biaxial nature of the nematic phase exhibited by the studied compound for those temperatures.

Journal Article↗
PubMed2005

Peak oxygen uptake. Myth and truth about an internationally accepted reference value.

This article critically examines the execution of VO(2)-peak testing in cardiac patients and questions their appropriate interpretation. In the first part, the most common clinical implications of VO(2)peak measurements are discussed: assessment of (changes in) functional capacity, evaluation of the necessity of invasive diagnostic/therapeutic measures, reference for exercise prescriptions, determination of prognosis. In the second part, important methodological problems and constraints are addressed and illustrated by references to scientific studies. Finally, recommendations are given for meaningful VO(2)peak testing. It is evident that failure to strictly follow such recommendations might result in misleading ergometric findings and, thus, in over- or underestimation of endurance capacity and/ or training effects.

Clinical Trials as Topic↗
PubMed2005

Neoadjuvant chemotherapy does not increase postoperative complication rate after resection of colorectal liver metastases.

BACKGROUND: This paper discusses, whether neoadjuvant chemotherapy has an impact on the rate of postoperative complications after primary resection of liver metastases from colorectal carcinoma. METHODS: Of 183 patients 64 were studied. The patients were subdivided into two matched groups of 32 patients each-prior neoadjuvant chemotherapy (CT-group) vs. (control-group, primary resection). RESULTS: There were no postoperative complications in 24 patients of the control group (75%) and 26 patients of the CT-group (81%). Following prior chemotherapy, no major complications such as liver failure were observed, even after extended resections. CONCLUSION: Neoadjuvant chemotherapy prior to surgical resection of colorectal liver metastases does not result in an increase of postoperative morbidity and mortality.

Adult↗
PubMed2005

[Missing data in the somatisation subscale of the scl-90-R due to a 'checklist effect': occurrence in different surveys and results of various imputation methods].

Item non-response is a potential threat to the validity of study results. Taking the somatisation subscale of the SCL-90-R as an example, we hypothesise a specific response pattern ("checklist-effect") that is characterised by symptom-free persons not checking the "not at all"-category. The present study analyses the extent and relevance of this postulated "checklist-effect". Our data is derived from a survey of n = 228 blue-collar workers who previously had filed applications for medical rehabilitation benefits (A1-study), and two additional surveys as well. We defined the "checklist-effect" by the following response pattern: (1) at least one missing value and (2) at least one valid item response and (3) no "not at all"-responses. Occurrence of the "checklist-effect" in the three datasets differed widely. 75 % of the responders in the A1-Study had complete data, 16.2 % a postulated "checklist-effect". Imputation of missing values under the assumption of a "checklist-effect" led to a reduction of missing data in the somatisation-subscale from 12.3 % to 0.4 %. Ignoring the "checklist-effect" would overestimate the symptom level. Possible explanations for the effect are discussed. However, the validity of this effect has yet to be proven via methodological studies.

Bias↗
PubMed2005

Ambulatory gas exchange measurements--current status and future options.

This article summarizes the scientific literature on portable devices used for the measurement of gas exchange during exercise. Firstly, the results from validity investigations are reviewed in terms of accuracy, reliability, and influence of additional weight during field testing. On the basis of these findings, at least two of the most often tested portable devices, MetaMax I/II and K2/K4 b (2), can be regarded as valid, with their results not differing substantially from (stationary) metabolic carts. The second part of the article provides an overview of ambulatory gas exchange applications which have been investigated so far. There is a number of descriptive (cross-sectional) studies that characterize the physiological profiles of different sports. In addition, some diagnostic tests of functional capacity have been validated, and a few investigations have assessed nutritional interventions and their effect on metabolism. Some indicate potential future directions including an evaluation of the efficacy of modifying metabolic pathways during exercise, e. g. by specifically designed training. Also, the extension of descriptive/cross-sectional investigations to typical training sessions will be worthwhile.

Exercise Test↗
PubMed2005

A conceptual framework for performance diagnosis and training prescription from submaximal gas exchange parameters--theory and application.

The first part of this article intends to give an applicable framework for the evaluation of endurance capacity as well as for the derivation of exercise prescription by the use of two gas exchange thresholds: aerobic (AerTGE) and anaerobic (AnTGE). AerT GE corresponds to the first increase in blood lactate during incremental exercise whereas AnTGE approximates the maximal lactate steady state. With very few constraints, they are valid in competitive athletes, sedentary subjects, and patients. In the second part of the paper, the practical application of gas exchange thresholds in cross-sectional and longitudinal studies is described, thereby further validating the 2-threshold model. It is shown that AerTGE and AnTGE can reliably distinguish between different states of endurance capacity and that they can well detect training-induced changes. Factors influencing their relationship to the maximal oxygen uptake are discussed. Finally, some approaches of using gas exchange thresholds for exercise prescription in athletes, healthy subjects, and chronically diseased patients are addressed.

Age Factors↗
PubMed2005

[Perceptions of quality of life in schizophrenic patients].

BACKGROUND: Subjective quality of life in schizophrenic persons is a commonly applied indicator in outcomes research. However, it remains unclear whether the content of the construct is adequately represented from the patients' point of view, and whether changing representations in the course of illness should be accounted for in terms of re-prioritization of the concept. PURPOSE: Identification of specific perceptions of quality of life (QoL) of schizophrenic persons and analysis of changes of those perceptions with increasing chronicity. METHODS: The present study is a reanalysis of responses to a short, structured, open-ended interview taken from different studies in social psychiatry research. 403 schizophrenic persons from different care settings (psychiatric hospitals, community based institutions) as well as 178 mentally healthy persons were interviewed with regard to positive and negative aspects of their QoL. A qualitative content-analysis resulted in a comprehensive hierarchy of categories. The proportion of persons who mentioned a respective QoL-aspect was compared. Relationship between chronicity and perceptions of QoL were analysed by means of chi (2)(trend)-tests. RESULTS: Schizophrenic persons mentioned about one fewer QoL domain compared to the mentally healthy (8.3 (sd = 2.8) vs. 9.6 (sd = 2.0), P < 0.001). They had fewer assertions on work aspects as well as in social domains (family, social relationships, partnership). The proportion of statements in social domains was negatively associated with the degree of chronicity. Among other things the schizophrenic persons showed a higher proportion of statements regarding "oral needs" (food, drinking-related statements, smoking) and (problems with) daily activities; both domains were associated with the degree of chronicity. DISCUSSION: Differences between schizophrenic and mentally healthy persons in their perceptions of QoL were more pronounced with increasing chronicity. It remains unclear at which point in the course of illness this is best understood in terms of re-prioritization or even re-conceptualization of the entire concept.

Adult↗
PubMed2005

Optimum peripheral drug deposition in patients with cystic fibrosis.

In order to identify the optimum particle size and breathing pattern for high peripheral deposition of inhaled drugs in patients with cystic fibrosis, regional deposition in these patients was studied systematically as a function of particle size, inhalation volume and flow rate. Regional deposition was assessed using the single-breath regional deposition technique in which the concentration profile of inhaled and exhaled non-radioactive, monodisperse test particles is analyzed. Using this technique particle deposition within the functional dead space volume and peripherally can be assessed. Regional deposition was measured in 12 patients with cystic fibrosis using 2, 3, 4, and 5.5 microm particles, inhalation volumes of 500, 1000, 1500, and 2000 cm(3), and inhalation flow rates of 100, 250, 500, and 750 cm(3)/sec. Peripheral deposition was highest when 2-3-microm particles were inhaled with air-flow rates of 250-500 cm(3)/sec. With these parameters peripheral deposition increased with increasing inhalation volume and reached values of about 60% of the total drug inhaled. It has been shown that high peripheral drug deposition can be achieved in patients with CF when inhalations are performed using an optimized combination of particle size and breathing pattern.

Administration, Inhalation↗
PubMed2005

Worm infestation and the negative association with eczema (atopic/nonatopic) and allergic sensitization.

BACKGROUND: Worm infestations may play a role in preventing allergies. There is a lack of epidemiological information from Western countries on the association between worm infestation and eczema. OBJECTIVE: To investigate the association between worm infestation and eczema in a proper temporal sequence and under consideration of allergic sensitization. METHODS: Two surveys were performed in East German school children. Questionnaire data included the history of eczema and worm infestation and their time of onset. Specific IgE antibodies to five common aeroallergens were measured and used to define nonatopic and atopic eczema. Logistic regression analyses were performed to control for relevant confounders (age, sex, parental school education and history of allergies). In order to confirm the findings a corresponding conditional regression analysis was applied on cases and controls matched by age and sex. RESULTS: A total of 4169 children participated (response 75 and 76%) who were, on average, 9.2 years old (47% girls). Overall 17.0% reported a prior worm infestation (Ascaris 44%, Oxyuris 33%) and 18.1% had a history of eczema. Eczema occurred significantly less frequent in children who had a worm infestation (prior to the onset of eczema) compared with children without such a history (8.1%vs 16.5%, OR(adj): 0.45, 95% CI: 0.33-0.60). The finding was confirmed by the corresponding matched case-control analysis (OR(adj): 0.57, 95% CI: 0.41-0.79). Atopic eczema was affected more by a prior worm infestation (OR(adj): 0.31, 95% CI: 0.18-0.56) than the nonatopic eczema (OR(adj): 0.58, 95% CI: 0.40-0.84). A total of 29.1% exhibited specific IgE antibodies to at least one aeroallergen. Sensitized children gave significantly less frequent a history of worm infestation (14.2%vs 18.3%, OR(adj): 0.74, 95% CI: 0.60-0.92). Stratified analysis revealed that this effect most pronounced for a sensitization to house dust mite. CONCLUSIONS: A worm infestation is associated with a reduced frequency of subsequent eczema, especially the atopic type. Furthermore allergic sensitization, especially to house dust mite, and worm infestation are negatively associated. The data support the concept that a lack of immune-stimulation by parasitic infections contributes to the development of allergies.

Case-Control Studies↗
PubMed2005

Does prolonged cycling of moderate intensity affect immune cell function?

BACKGROUND: Prolonged exercise may induce temporary immunosuppression with a presumed increased susceptibility for infection. However, there are only few data on immune cell function after prolonged cycling at moderate intensities typical for road cycling training sessions. METHODS: The present study examined the influence on immune cell function of 4 h of cycling at a constant intensity of 70% of the individual anaerobic threshold. Interleukin-6 (IL-6) and C-reactive protein (CRP), leukocyte and lymphocyte populations, activities of natural killer (NK), neutrophils, and monocytes were examined before and after exercise, and also on a control day without exercise. RESULTS: Cycling for 4 h induced a moderate acute phase response with increases in IL-6 from 1.0 (SD 0.5) before to 9.6 (5.6) pg/ml 1 h after exercise and CRP from 0.5 (SD 0.4) before to 1.8 (1.3) mg/l 1 day after exercise. Although absolute numbers of circulating NK cells, monocytes, and neutrophils increased during exercise, on a per cell basis NK cell activity, neutrophil and monocyte phagocytosis, and monocyte oxidative burst did not significantly change after exercise. However, a minor effect over time for neutrophil oxidative burst was noted, tending to decrease after exercise. CONCLUSIONS: Prolonged cycling at moderate intensities does not seem to seriously alter the function of cells of the first line of defence. Therefore, the influence of a single typical road cycling training session on the immune system is only moderate and appears to be safe from an immunological point of view.

Acute-Phase Reaction↗