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Biomedical subjects

Klaus Dietz

Publications and source records attributed to Klaus Dietz.

At least 19 recordsLinked to original sources
PubMed2007

Differential radioactive quantification of protein abundance ratios between benign and malignant prostate tissues: cancer association of annexin A3.

A differential quantitative protein expression study, comparing matched prostate cancerous and benign tissues from 31 patients, revealed proteins newly associated with prostate cancer. Average effects for 17 proteins whose abundance was significantly different (p<0.01) across patients ranged from 1.5- to 6.1-fold, and included a number of known cancer markers. The most differentially abundant proteins between cancer and benign samples were isopeptidase T, serum amyloid P (SAP), annexin A3 (ANXA3) and mitochondrial enoyl coenzyme-A hydratase. SAP is restricted to stroma in healthy tissue, and the lower abundance in tumours may be explained by the reduced stromal content. ANXA3 is present in healthy epithelial cells, exhibits strong staining in precancerous prostatic intraepithelial neoplasia, and is relatively less abundant in individual tumour cells of increasing Gleason pattern (GP), despite exhibiting higher overall tissue abundance in tumours. ANXA3 staining was predominantly cytoplasmic, yet nuclear localization was also observed. Strongly staining single cells, possibly phagocytes, were interspersed in highly dedifferentiated GP5 tumour areas among tumour cells without measurable ANXA3. Local recurrent androgen ablation therapy-resistant tumours exhibit heterogenous low levels of ANXA3 staining. Results are discussed focussing on the potential implications for tumour tissues.

Adult↗
PubMed2007

Bipolar radiofrequency ablation using internally cooled electrodes in ex vivo bovine liver: prediction of coagulation volume from applied energy.

OBJECTIVE: We sought to evaluate the relationship between parameters of bipolar radiofrequency (RF) ablation using internally cooled electrodes. MATERIALS AND METHODS: Bipolar RF ablations (n = 24) were performed in ex vivo bovine liver using an internally cooled applicator with 2 electrodes located on the same shaft. The power-output was systematically varied (20-75 W). On the basis of our experimental data, mathematical functions were fitted and the goodness-of-fit was assessed by the parameter R. RESULTS: The duration to induce an increase of tissue resistance and the amount of applied energy increased with a decreased power-output. The maximum short-axis was 4.5 cm (20 W) and required an application of 64 kilojoules (kJ). The volume of coagulation can be determined as a function of the duration of energy application (R = 0.954) and the amount of applied energy (R = 0.945). CONCLUSION: The amount of applied energy and the duration of energy application can predict the volume of induced coagulation and may be useful to control internally cooled bipolar RF ablation.

Animals↗
PubMed2006

Evaluation of complications of three different types of proximal extra-articular femur fractures: differences in complications, age, sex and surviving rates.

The comparability of studies of extra-articular proximal femur fractures is compromised by the lack of a widely accepted, simple classification system with clinical and prognostic relevance. The aim of the study is to define the complication profile as well as differences relating to age, gender and survival rate of simple trochanteric fractures, intertrochanteric comminuted and subtrochanteric fractures. Records of 335 consecutive patients were analysed. Patients had a median follow-up of 10 (1-56) months, and were treated operatively with three intramedullary nailing systems. Simple trochanteric fractures (n=67) show wound healing problems (1.5%). Median age is m/f 77(45-98) years/ 85(39-101), and two-year survival rate is m/f 50.3%/ 84.9%. Intertrochanteric comminuted fractures (n=204) show the highest complications (25%), 9.7% femoralhead perforations, 3.5% hardware related problems and 11.8% wound healing problems. Median age is m/f 75(41-94) years/ 85(54-100), survival rate is m/f 92.7%/ 66.5%. Complication rate is 17.0% in subtrochanteric fractures (n=64), no femoralhead perforation but 9.1% other hardware problems and 7.8% wound healing problems. Median age is m/f 72(24-91) years/ 83(38-99), survival rate is m/f 92.3%/ 67.9%. Females show higher complication rates compared to males (19% versus 10%). The three types of fractures show different patterns of complications, survival rates, age, and sex distribution.

Aged↗
PubMed2006

Interobserver and intraobserver agreement of Lenke and King classifications for idiopathic scoliosis and the influence of level of professional training.

STUDY DESIGN: This is a blinded study of radiographs by observers with different levels of professional training. OBJECTIVES: To determine whether the level of professional training on nonmeasured and premeasured radiographs would affect reliability of Lenke's and King's classifications for adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Both classification systems have been studied for their reliability, mainly by observers with a high level of experience in orthopedics and scoliosis surgery using premeasured radiographs. METHODS: Examination of radiographs of 60 operative cases of adolescent idiopathic scoliosis was performed. On 5 occasions, 3 observers with a completely different degree of professional training measured and classified preoperative radiographs according to Lenke's or King's criteria. The results were determined by calculating the interobserver and intraobserver agreement and were quantified using two-rater and multirater kappa statistics. RESULTS: The Lenke and King classifications demonstrated poor to fair interobserver and good intraobserver agreement on nonmeasured radiographs. Both classifications demonstrated good to excellent interobserver agreement on premeasured radiographs. CONCLUSIONS: The results confirm that both classifications have a good reliability. On nonmeasured radiographs, the degree of professional training and the measurement process seem to influence the outcome. On premeasured radiographs, the interobserver agreement does not seem to be influenced by the level of professional training.

Adolescent↗
PubMed2006

The minimum effort required to eradicate infections in models with backward bifurcation.

We study an epidemiological model which assumes that the susceptibility after a primary infection is r times the susceptibility before a primary infection. For r = 0 (r = 1) this is the SIR (SIS) model. For r > 1 + (mu/alpha) this model shows backward bifurcations, where mu is the death rate and alpha is the recovery rate. We show for the first time that for such models we can give an expression for the minimum effort required to eradicate the infection if we concentrate on control measures affecting the transmission rate constant beta. This eradication effort is explicitly expressed in terms of alpha,r, and mu As in models without backward bifurcation it can be interpreted as a reproduction number, but not necessarily as the basic reproduction number. We define the relevant reproduction numbers for this purpose. The eradication effort can be estimated from the endemic steady state. The classical basic reproduction number R0 is smaller than the eradication effort for r > 1 + (mu/alpha) and equal to the effort for other values of r. The method we present is relevant to the whole class of compartmental models with backward bifurcation.

Algorithms↗
PubMed2006

Chloride and bicarbonate have similar affinities to the intestinal anion exchanger DRA (down regulated in adenoma).

DRA (down regulated in adenoma, SLC26A3) is an anion exchanger that mediates electroneutral NaCl absorption in the ileum and proximal colon together with NHE3 (Na/H exchanger isoform 3), and that is involved in duodenal and possibly pancreatic bicarbonate secretion. Thus, its chloride and bicarbonate affinities are important for both processes. [Cl]i and pHi transients were measured using MQAE and BCECF. HEK293 cells stably expressing DRA were exposed to 0 mM Cl at various [HCO3] (9 to 51 mM, at 5% CO2 or 15 to 57 mM, at pH 7.5) to determine the HCO3 affinity. After intracellular Cl depletion, 10, 30, and 90 mM Cl were readded at various [HCO3]s to determine the relative Cl and HCO3 affinities. The k0.5 for extracellular HCO3 is between 18.5 and 32.8 mM. Cl and HCO3 compete with similar affinities for transport by DRA. DRA activity is independent of pHo between 7.0 and 7.75. DRA is activated by alkaline pHi. Competition of Cl and HCO3 does not significantly impair NaCl absorption, because in the ileum and colon, luminal Cl is comparably high. Activation at alkaline pHi supports functional coupling of DRA and NHE3 by the subapical pHi. In the distal pancreatic ductal system, luminal HCO3 is high compared to luminal Cl. Under these conditions, competition of Cl and HCO3 is difficult to reconcile with a role of DRA in Cl reabsorption in exchange for HCO3. Our data, thus, provide indirect evidence against a role of DRA in pancreatic HCO3 secretion.

Antiporters↗
PubMed2006

Peripheral arteries: treatment with antibodies of platelet receptors and reteplase for thrombolysis--APART trial.

PURPOSE: To prospectively compare the safety and efficacy of combination therapy with the glycoprotein IIb/IIIa antagonist abciximab plus the third-generation thrombolytic agent reteplase versus those of therapy with the standard thrombolytic agent urokinase plus abciximab. MATERIALS AND METHODS: The study was approved by the local ethics committee, and patient informed consent was obtained. Patients with peripheral arterial occlusions less than 60 days old (n=120) were enrolled in the study: 50 patients (32 men, 18 women; mean age, 67 years; range, 23-88 years) received reteplase plus abciximab and 70 patients (36 men, 34 women; mean age, 68 years; range, 28-88 years) received urokinase plus abciximab. Study end points were the rate of major complications at 30 days, therapeutic success, and survival without open surgery or major amputation at follow-up. Fisher exact test was used to compare treatment groups with respect to dichotomous variables, and the event-free-survival probabilities were calculated with the Kaplan-Meier method. For the comparison of the lengths of occlusions among the groups, a two-sample t test was used. RESULTS: Therapeutic success (P=.7) did not differ between the groups, whereas the time required for thrombolysis was lower in the urokinase-plus-abciximab group (P=.001). Patients who received reteplase plus abciximab tended to develop more minor complications (mainly bleeding events) (P<.001). During long-term follow-up (2-4 years), no group differences were observed. The reocclusion rate was 48% (22 of 46) in the reteplase-plus-abciximab group and 45% (29 of 64) in the urokinase-plus-abciximab group. Only two of 120 major amputations were counted in the follow-up period. CONCLUSION: The proposed regimen resulted in only a limited number of major complications, and the low amputation rate in both groups may be attributed to abciximab.

Abciximab↗
PubMed2006

Multipolar radiofrequency ablation with internally cooled electrodes: experimental study in ex vivo bovine liver with mathematic modeling.

PURPOSE: To evaluate the size and geometry of thermally induced coagulation by using multipolar radiofrequency (RF) ablation and to determine a mathematic model to predict coagulation volume. MATERIALS AND METHODS: Multipolar RF ablations (n = 80) were performed in ex vivo bovine livers by using three internally cooled bipolar applicators with two electrodes on the same shaft. Applicators were placed in a triangular array (spacing, 2-5 cm) and were activated in multipolar mode (power output, 75-225 W). The size and geometry of the coagulation zone, together with ablation time, were assessed. Mathematic functions were fitted, and the goodness of fit was assessed by using r(2). RESULTS: Coagulation volume, short-axis diameter, and ablation time were dependent on power output and applicator distance. The maximum zone of coagulation (volume, 324 cm(3); short-axis diameter, 8.4 cm; ablation time, 193 min) was induced with a power output of 75 W at an applicator distance of 5 cm. Coagulation volume and ablation time decreased as power output increased. Power outputs of 100-125 W at applicator distances of 2-4 cm led to a reasonable compromise between coagulation volume and ablation time. At 2 cm (100 W), coagulation volume, short-axis diameter, and ablation time were 66 cm(3), 4.5 cm, and 19 min, respectively; at 3 cm (100 W), 90 cm(3), 5.2 cm, and 22 min, respectively; at 4 cm (100 W), 132 cm(3), 6.1 cm, and 27 min, respectively; at 2 cm (125 W), 56 cm(3), 4.2 cm, and 9 min, respectively; at 3 cm (125 W), 73 cm(3), 4.9 cm, and 12 min, respectively; and at 4 cm (125 W), 103 cm(3), 5.5 cm, and 16 min, respectively. At applicator distances of 4 cm (>125 W) and 5 cm (>100 W), the zones of coagulation were not confluent. Coagulation volume (r(2) = 0.80) and RF ablation time (r(2) = 0.93) were determined by using the mathematic model. CONCLUSION: Multipolar RF ablation with three bipolar applicators may produce large volumes of confluent coagulation ex vivo. A compromise is necessary between prolonged RF ablations at lower power outputs, which produce larger volumes of coagulation, and faster RF ablations at higher power outputs, which produce smaller volumes of coagulation.

Animals↗
PubMed2006

Treating Class II patients with removable plates and functional orthopedic appliances-the importance of anterior tooth inclination and direction of growth on treatment outcome.

OBJECTIVE: To determine the influence of physiological growth pattern and anterior tooth inclination on the outcome in Class II patients treated with removable orthodontic plates and functional orthodontic appliances. PATIENTS AND METHODS: After recruiting 50 patients with an upper anterior proclination of 1-SN >or= 107 degrees for this retrospective study, another 50 patients with a retroclination of 1-SN <or= 95 degrees were also included. All patients initially presented a skeletal Class II relationship with a distoclusion of at least one premolar width in the region of the first molars. All patients were evaluated separately by gender and additionally subdivided into three subgroups with a horizontal, neutral, or vertical craniofacial configuration. Treatment with removable orthodontic plates (pretreatment) and functional orthodontic appliances was initiated in mixed dentition. Pre- and post-treatment lateral cephalograms were evaluated for each patient. RESULTS: Dento-alveolar analysis showed that the inclination of the upper incisors changed in the direction of the clinical standard value independent of the craniofacial configuration, although full correction using removable orthodontic plates and functional orthodontic appliances was not always achieved. Similarly good treatment outcomes were achieved with regard to overjet and overbite. The lower incisors of all patients were in proclination after treatment. The ANB angle was reduced in both groups. Nevertheless, on average a skeletal Class II persisted in the Class II, Division 2 patients, while Class II, Division 1 patients with horizontal craniofacial configurations attained skeletal Class I. CONCLUSIONS: Treatment of Class II patients with removable appliances resulted in differences depending on anterior tooth inclination (Class II, Division 1 and II, Division 2) and craniofacial configuration. These differences must be taken into account during treatment planning. Complete treatment success with regard to sagittal jaw balance is very difficult to achieve with removable orthodontic plates (pre-treatment) and functional orthodontic appliances alone in Class II, Division 1 cases with a vertical craniofacial configuration and generally in Class II, Division 2 cases. A particularly favorable constellation for removable treatment is a Class II, Division 1 situation with a horizontal craniofacial configuration and retroclined or orthognathic mandibular anteriors.

Bone Development↗
PubMed2006

Alveolar recruitment during prone position: time matters.

Alveolar recruitment is one of the beneficial effects of prone positioning in patients with ARDS (acute respiratory distress syndrome). However, responses vary among patients and, therefore, we hypothesized that alveolar recruitment is an individual time-dependent process and its measurement might be helpful to 'dose' prone positioning individually. In 13 patients diagnosed with ARDS, EELV (end-expiratory lung volume) was measured in the supine position, immediately after turning to the prone position, at 1, 2, 4 and 8 h in the prone position and after returning to the supine position. Responders were defined based on a 30% increase in oxygenation. EELV increased in responders, whereas it remained constant in non-responders. The time course was different in individual patients. In some responders, a plateau was reached as early as 2-4 h, whereas, in others, 8 h of prone positioning was not sufficient to allow complete recruitment. The increase in lung volume was associated with both an increase in arterial oxygenation and a decrease in venous admixture. Furthermore, responders had significantly lower baseline EELVs than non-responders. In conclusion, alveolar recruitment during prone positioning has been characterized as an individual time-dependent process. Its measurement might be useful to apply prone positioning more individually and might also help to identify responders.

Adult↗
PubMed2006

Albumin in immunohistochemistry: Foe and friend.

Immunohistochemical procedures constitute a high methodological value in both pathologic diagnostics and research. Staining quality depends on a large variety of interference factors. Primarily, background staining reduces the quality of evaluation by reducing the chromatic discrimination. For the identification of important interference factors, various incubation steps and composition of solutions recommended in routine protocols were altered or omitted in our study. Surprisingly, the most important effect concerning background staining reduction could be significantly attributed to the omission of albumin which usually is recommended as a reducer of background stainings. However, in contrast to this negative effect, albumin could also increase specific staining intensity. These findings lead to the recommendation of a careful use of albumin in immunohistochemistry because of the dichotomous effects mentioned above. Furthermore, these results imply that in case of a good specific staining pattern, the use of albumin in immunohistochemical solutions merely exerts significant negative background staining effects.

Central Nervous System↗
PubMed2006

Comparison of Gadolinium-BOPTA and Ferucarbotran-enhanced three-dimensional T1-weighted dynamic liver magnetic resonance imaging in the same patient.

OBJECTIVES: We sought to compare signal changes using Ferucarbotran and gadobenate dimeglumine (Gd-BOPTA) in dynamic 3D T1-weighted (T1w) GRE imaging of the liver. MATERIAL AND METHODS: Thirty patients were prospectively included in the study. All patients underwent 2 high-field magnetic resonance (MR) examinations: first with Gd-BOPTA (Gd) and then after a mean interval of 4 days with ferucarbotran (Feru). Dynamic MRI was obtained with a 3D T1w GRE sequence (TR 6.33, TE 2.31, flip angle 20 degrees ). Contrast enhanced scans were assessed before intravenous injection of the contrast agent (precontrast), and postcontrast during the arterial phase (30 seconds), portal venous phase (60 seconds), and equilibrium phase (120 seconds). The signal intensities (SIs) of liver, spleen, aorta, and portal vein were defined by region of interest measurements. Signal intensity changes (SICs) and percentage signal intensity change (PSIC) were calculated using the formulas SIC=(SI pre - SI post)/SI pre and PSIC=SIC x 100%. RESULTS: Positive signal enhancement was observed after intravenous injection of Feru during all dynamic measurements, whereas the mean SI values were lower compared with Gd. During the portal venous phase the mean SI of Gd was up to a factor of 2.1 higher (portal vein). The widest difference of SIC was observed during the equilibrium phase for liver parenchyma (Gd, 1.03; Feru, 0.24). The dynamic signal courses were similar for liver, portal vein and aorta. Different signal courses were obtained for the spleen. CONCLUSIONS: Feru-enhanced T1w dynamic images demonstrated significant signal increases for liver, vessels, and spleen but overall lower signal intensities than Gd-BOPTA. The dynamic signal courses of ferucarbotran were similar to that of Gd-BOPTA during ll perfusion phases except in the spleen. Thus, it may be possible to detect typical enhancement pattern of focal liver lesions with Feru-enhanced dynamic T1w MRI.

Adult↗
PubMed2006

Doping in fitness sports: estimated number of unreported cases and individual probability of doping.

AIMS: Recent studies have suggested that the use of doping substances and particularly of anabolic androgenic steroids (AAS) is often practised by fitness centre visitors. These studies employed direct interview techniques and questionnaires to assess the estimated number of unreported cases of doping. Because people hesitate to provide compromising information about themselves, these techniques are subject to response errors. In this study we applied an alternative interview technique to assess more accurately unreported cases of doping in fitness centres. DESIGN AND PARTICIPANTS: The present investigation employed the randomized response technique (RRT) to reduce response errors. A cohort of 500 people from 49 fitness centres participated in this study. FINDING: The RRT revealed a high prevalence of doping (12.5%). In addition, and most importantly, the present RRT study revealed an alarmingly high prevalence of illicit drug use, specifically of cocaine use, that has been severely underestimated by previous studies. CONCLUSIONS: The RRT confirmed previously estimated rates of AAS use assessed by direct interview techniques and voluntary questionnaires, but uncovered a much higher usage rate of illicit drugs among fitness centre visitors. This outcome enabled us to construct a 'probability' rating for the use of doping substances in fitness centre visitors. Given its high prevalence and the predominant use of AAS, doping among fitness centre visitors is an issue of extreme relevance for the health care system. Our study may help to characterize further doping substance users and to develop and apply prevention and intervention programmes specifically to individuals at high risk.

Adult↗
PubMed2006

A randomized controlled trial assessing infectious disease risks from bathing in fresh recreational waters in relation to the concentration of Escherichia coli, intestinal enterococci, Clostridium perfringens, and somatic coliphages.

We performed epidemiologic studies at public freshwater bathing sites in Germany to provide a better scientific basis for the definition of recreational water quality standards. A total of 2,196 participants were recruited from the local population and randomized into bathers and nonbathers. Bathers were exposed for 10 min and had to immerse their head at least three times. Water samples for microbiological analysis were collected at 20-min intervals. Unbiased concentration-response effects with no-observed-adverse-effect levels (NOAELs) were demonstrated for three different definitions of gastroenteritis and four fecal indicator organisms. Relative risks for bathing in waters with levels above NOAELs compared with nonbathing ranged from 1.8 (95% CI, 1.2-2.6) to 4.6 (95% CI, 2.1-10.1), depending on the definition of gastroenteritis. The effect of swallowing water provided additional evidence for true dose-response relationships. Based on the NOAELs, the following guide values for water quality are suggested: 100 Escherichia coli, 25 intestinal enterococci, 10 somatic coliphages, or 10 Clostridium perfringens per 100 mL. Recreational water quality standards are intended to protect the health of those consumers who are not already immune or resistant to pathogens that may be associated with indicator organisms. In contrast to current World Health Organization recommendations, we concluded that standards should be based on rates of compliance with NOAELs rather than on attributable risks determined above NOAELs, because these risks depend mainly on the unpredictable susceptibility of the cohorts. Although in theory there is no threshold in real concentration-response relationships, we demonstrated that a NOAEL approach would be a more robust and practical solution to the complex problem of setting standards.

Clostridium perfringens↗
PubMed2006

Digital surface photogrammetry for anthropometric analysis of the cleft infant face.

OBJECTIVE: To analyze the three-dimensional morphology of the cleft infant face with digital surface photogrammetry. DESIGN: Fifty plaster casts of unoperated infants with cleft lip and palate were imaged three-dimensionally with digital surface photogrammetry. Twenty-one standard craniofacial measurements were taken. The plaster casts were divided into 4 groups with unilateral, bilateral, complete, and incomplete clefts of the lip and palate. The measurements were compared with standard values for healthy infants. RESULTS: Significant differences (p < .0025) were found for the alar base width (33% to 55%), the alar base root width (59% to 103%), the width of the nose (7% to 25%), the length of the alar wing (18% to 25%), and the intercanthal (6% to 17%) and biocular (4% to 12%) width, depending on the cleft type. The vertical dimensions of the nose and the upper lip did not differ significantly from the controls. CONCLUSION: This study describes preliminary data on the cleft infant facial deformity. The obtained results were mainly in agreement with data in the limited literature. Three-dimensional photogrammetry has proven to be reliable and can be applied more readily to potentially uncooperative patients.

Cephalometry↗
PubMed2006

Quality of life in patients with oropharyngeal carcinoma after primary surgery and postoperative irradiation.

OBJECTIVE: To assess quality of life in patients with oropharyngeal carcinoma after primary surgery and postoperative irradiation. STUDY DESIGN: Retrospective chart review and patient response to the Short Form 36 (SF-36) Health Survey and the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 and QLQ-H&N35 questionnaires. SETTING: A tertiary care university hospital. RESULTS: One hundred sixty-nine patients with oropharyngeal carcinoma underwent primary surgery followed by postoperative irradiation between January 1997 and February 2002. Eighty-eight disease-free survivors were identified in September 2002 and included in this study. The questionnaires were completed by 34 patients (39% completion rate). Median follow-up was 2.3 years (range 0.5-4.9 years). In oropharyngeal carcinoma patients, five scales of the SF-36 showed significantly reduced scores in comparison with the normal German population: physical functioning, role functioning - physical, general health, social functioning, and role functioning - emotional. Posttreatment scores from the literature fell within the 95% confidence interval of our data except one out of fifteen scales of the EORTC QLQ-C30 questionnaire and six out of eighteen scales of the EORTC QLQ H&N35 questionnaire. The comparison of our data with data from the reviewed literature produced similar results. CONCLUSIONS: General quality of life was reduced in our oropharyngeal carcinoma patients. Primary surgery and postoperative irradiation demonstrated similar results in different studies.

Adult↗
PubMed2006

A model for natural immunity to asexual blood stages of Plasmodium falciparum malaria in endemic areas.

Most mathematical models for acquired immunity to Plasmodium falciparum consider effects of immunity on duration of infection and infectiousness, but do not consider the most evident effect of immunity, which is to reduce parasite densities. Few attempts have been made to fit such models to field data. We propose a stochastic simulation model to predict the distributions of P. falciparum parasite densities in endemic areas, in which acquired immunity acts by reducing parasite densities. We have fitted this model to age-specific prevalence and geometric mean densities from settings in Ghana, Nigeria, and Tanzania. The model appears to reproduce reasonably well the parasitologic patterns seen in malariologic surveys in endemic areas and is appropriate for predicting the impact of interventions such as vaccination in the context of continual exposure to P. falciparum.

Adolescent↗