Sven Schmidt

Studies on the time frame for ossification of the medial epiphysis of the clavicle as revealed by CT scans.

The authors retrospectively analyzed 629 CT images of patients aged between 15 and 30 years produced during multiple trauma diagnostics at the Unfallkrankenhaus Berlin. For the purposes of this study, the authors reliably determined the ossification status of the medial epiphysis of the clavicle in 556 cases, using the classification of stages by Schmeling et al. In both sexes, stage 2 was first noted at age 15. In male patients, the earliest occurrence of stage 3 was noted at age 17, in female patients at age 16. Stage 4 was first achieved by both sexes at age 21. Stage 5 was first noted in female patients at age 21 and in male patients at age 22, which is 4 or 5 years earlier than was observed by a comparable study using conventional radiographs. The partial-volume effect in computed tomography using the thick slice scanning mode was discussed as a possible explanation for this early visualization. The question of how slice thickness affects the age intervals between ossification stages identified by CT examinations should be examined in additional studies.

Increased plasma phenylacetic acid in patients with end-stage renal failure inhibits iNOS expression

NO prevents atherogenesis and inflammation in vessel walls by inhibition of cell proliferation and cytokine-induced endothelial expression of adhesion molecules and proinflammatory cytokines. Reduced NO production due to inhibition of either eNOS or iNOS may therefore reinforce atherosclerosis. Patients with end-stage renal failure show markedly increased mortality due to atherosclerosis. In the present study we tested the hypothesis that uremic toxins are responsible for reduced iNOS expression. LPS-induced iNOS expression in mononuclear leukocytes was studied using real-time PCR. The iNOS expression was blocked by addition of plasma from patients with end-stage renal failure, whereas plasma from healthy controls had no effect. Hemofiltrate obtained from patients with end-stage renal failure was fractionated by chromatographic methods. The chromatographic procedures revealed a homogenous fraction that inhibits iNOS expression. Using gas chromatography/mass spectrometry, this inhibitor was identified as phenylacetic acid. Authentic phenylacetic acid inhibited iNOS expression in a dose-dependent manner. In healthy control subjects, plasma concentrations were below the detection level, whereas patients with end-stage renal failure had a phenylacetic acid concentration of 3.49 +/- 0.33 mmol/l (n = 41). It is concluded that accumulation of phenylacetic acid in patients with end-stage renal failure inhibits iNOS expression. That mechanism may contribute to increased atherosclerosis and cardiovascular morbidity in patients with end-stage renal failure.

A novel human gastric primary cell culture system for modelling Helicobacter pylori infection in vitro

Background and aims Helicobacter pylori is the causative agent of gastric diseases and the main risk factor in the development of gastric adenocarcinoma. In vitro studies with this bacterial pathogen largely rely on the use of transformed cell lines as infection model. However, this approach is intrinsically artificial and especially inappropriate when it comes to investigating the mechanisms of cancerogenesis. Moreover, common cell lines are often defective in crucial signalling pathways relevant to infection and cancer. A long-lived primary cell system would be preferable in order to better approximate the human in vivo situation. Methods Gastric glands were isolated from healthy human stomach tissue and grown in Matrigel containing media supplemented with various growth factors, developmental regulators and apoptosis inhibitors to generate long-lasting normal epithelial cell cultures. Results Culture conditions were developed which support the formation and quasi-indefinite growth of three dimensional (3D) spheroids derived from various sites of the human stomach. Spheroids could be differentiated to gastric organoids after withdrawal of Wnt3A and R-spondin1 from the medium. The 3D cultures exhibit typical morphological features of human stomach tissue. Transfer of sheared spheroids into 2D culture led to the formation of dense planar cultures of polarised epithelial cells serving as a suitable in vitro model of H. pylori infection. Conclusions A robust and quasi-immortal 3D organoid model has been established, which is considered instrumental for future research aimed to understand the underlying mechanisms of infection, mucosal immunity and cancer of the human stomach.

Noninvasive evaluation of renal allograft fibrosis by transient elastography--a pilot study.

Chronic allograft injury (CAI) is the most common cause of graft failure after the first year of transplantation. To date, only protocol biopsies can reveal subclinical disease. Transient elastography (TE) is a novel noninvasive technique that has demonstrated high reliability in the assessment of liver fibrosis. This study evaluates the feasibility of TE for the assessment of renal allograft fibrosis. Fifty‐seven patients underwent TE by the FibroScan® device. Biopsies were performed in 20 patients. Measurement of parenchymal stiffness by TE was successful in 55 of 57 patients (96.5%). Stiffness was significantly correlated to the extent of interstitial fibrosis (Pearson r: 0.67, P: 0.002, R2: 0.45) and inversely related to estimated glomerular filtration rate (eGFR) (Pearson r: −0.47, P: 0.0003, R2: 0.22). Stiffness values of patients with an eGFR >50 ml/min were significantly lower than in patients with an eGFR ≤50 ml/min (22.2 ± 11.0 vs. 37.1 ± 14.2 kPa, P: 0.0005). The stiffness values of CAI Banff grades 0–1 differed significantly from grade 2 (P: 0.008) and grade 3 (P: 0.046). Parenchymal stiffness measured by TE reflects interstitial fibrosis in kidney allografts. A longitudinal assessment of parenchymal stiffness might be a powerful tool to identify patients with CAI who benefit from biopsy and consequent adaptation of the immunosuppressive regime.

Too Old to Benefit from Sports? The Cardiovascular Effects of Exercise Training in Elderly Subjects Treated for Isolated Systolic Hypertension

Background: Hypertension in the elderly is commonly characterized by an elevation of pulse pressure. With regard to advanced arteriosclerosis and limited physical fitness, doubt was casted whether elderly patients still achieve relevant cardiovascular benefits by physical exercise. The present work examines the impact of pulse pressure as a footprint of vascular ageing on cardiovascular benefits of endurance training in elderly hypertensives. Methods: 54 patients ≧60 years with systolic 24-hour ambulatory blood pressure (ABP) >140 mm Hg and/or antihypertensive treatment and diastolic ABP ≤90 mm Hg were randomly assigned to sedentary activity or a 12-week treadmill exercise program (target lactate 2.5 ± 0.5 mmol/l). Results: Exercise significantly decreased systolic and diastolic ABP by 8.5 ± 8.2 and 5.1 ± 3.7 mm Hg (p < 0.001 each) and increased physical performance. Arterial compliance remained unchanged, whereas endothelium-dependent vasodilation – measured by flow-mediated dilation – significantly increased from 5.6 ± 1.7 to 7.9 ± 3.0% (p < 0.007). After adjustment for initial systolic ABP, pulse pressure did not affect the change of BP. Conclusion: The exercise-induced reduction of BP, which is mediated by improved endothelial function, is independent of pulse pressure. Thus, physical exercise is a helpful adjunct to control BP even in old hypertensives with markedly increased arterial stiffness.

Technique of bile duct reconstruction and management of biliary complications in right lobe living donor liver transplantation

Abstract:  From December 1999 to January 2002, 50 right lobe living donor liver transplantations were performed. The donor operations included an intraoperative cholangiography to elicit variations in bile duct anatomy. The biliary reconstruction was done whenever possible as an end‐to‐end microanastomosis of the donor right hepatic duct with the recipients bile duct. As a result of the early segmental branching of the donor biliary tree, two segment bile ducts had to be anastomosed in 20 patients and three segment bile ducts in three patients. In 12 patients, a Roux‐en‐Y hepaticojejunostomy was performed. All anastomoses were drained externally. We observed two leakages at the resection surface which could be treated successfully by an external drainage. Six leaks occurred at the site of end‐to‐end biliary anastomoses. Twice the problem could be conservatively solved placing a stent percutaneously. In two patients a hepaticojejunostomy was performed after a bile duct necrosis. In two patients with an anastomotic leak, occurring 3 d, respectively, 3 month after the original transplantation, the bile duct could be directly reconstructed over a T‐tube. Two anastomotic stenoses were observed, one in combination with a leak treated by percutaneous stent implantation and the second, 3 month after transplantation which was treated surgically. Biliary reconstruction after living donor liver transplantation requires microsurgical techniques and can be performed as a direct end‐to‐end anastomosis in most cases. Biliary complications were treated by percutaneous drainage or surgical revision in all cases.

Reference data for the Thiemann–Nitz method of assessing skeletal age for the purpose of forensic age estimation

The aim of this study was to determine the statistical parameters of deviation in the Thiemann–Nitz method for use in forensic age diagnostics. To this effect, 402 hand radiograms, originally taken in two large German cities between 1983 and 2002 for the purpose of diagnosing trauma, were analyzed. At the time of examination, the patients were aged between 10 and 18 years. The study presents the mean, standard deviation, and median, with lower and upper quartiles, for the skeletal ages of 11.0 through 18.0 years. The simple standard deviations range between 0.2 and 1.2 years. To increase the accuracy of age estimates and improve the identification of age-relevant developmental disorders in forensic age estimation practice, the methods for determining skeletal age should always be combined with a physical and dental examination. In addition, the expert opinion should pay attention to the issue of different modernization levels in relevant populations.

Studies in use of the Greulich–Pyle skeletal age method to assess criminal liability

In recent years, skeletal age determination has become increasingly important for determining the age of live subjects as part of criminal investigation. The most widely used method worldwide to determine skeletal age is the Greulich-Pyle atlas method. The present study examines the suitability of the Greulich-Pyle method given the particular requirements of forensic age estimates. It is a retrospective analysis of 649 hand radiographs originally taken from persons aged between 1 and 18 years, separately for each sex. If the Greulich-Pyle method is used exclusively, it can be claimed with a probability of 95% that a young man has reached the age of 14 years and thus the age of criminal liability if his skeletal age is at least 15.5 years. In the case of female subjects, even if they are estimated as being 16.0 years old, it cannot be asserted with a probability of 95% that they have reached the age of 14. To reduce the margin of error of age estimates, determining the skeletal age should always go hand in hand with a physical examination to determine indications of sexual maturity and a dental examination to record dental status. The reference values given in the present study can be applied to members of all ethnic groups for age estimate purposes. If the person under examination has a different socio-economic status, the expert performing the age estimate should address this issue in his expert opinion and discuss the possible effects that might have on the age diagnosis.

Influence of the examiner’s qualification and sources of error during stage determination of the medial clavicular epiphysis by means of computed tomography

Computed tomography (CT) of the medial clavicular epiphysis has been well established in forensic age estimations of living individuals undergoing criminal proceedings. The present study examines the influence of the examiner’s qualification on the determination of the clavicular ossification stage. Additionally, the most frequent sources of error made during the stage assessment process should be uncovered. To this end, thin-slice CT scans of 1,420 clavicles were evaluated by one inexperienced and two experienced examiners. The latter did the evaluations in consensus. Two classification systems, a five-stage system and a substaging system for the main stages 2 and 3, were used. Prior to three of his six assessment sessions, the inexperienced examiner was specifically taught staging of clavicles. Comparison of the examiners’ results revealed increasing inter- and intraobserver agreements with increasing state of qualification of the inexperienced examiner (from κ= 0.494 to 0.674 and from κ= 0.634 to 0.783, respectively). The attribution of a not-assessable anatomic shape variant to an ossification stage was identified as the most frequent error during stage determination (n= 349), followed by the overlooking of the epiphyseal scar defining stage 4 (n= 144). As to the clavicular substages, classifying substage 3a instead of 3b was found to be the most frequent error (n= 69). The data of this study indicate that κ values must not be considered as objective measures for inter- and intraobserver agreements. Furthermore, a high degree of specific qualification, particularly the knowledge about the diversity of anatomic shape variants, appears to be mandatory and indispensable for reliable evaluation of the medial clavicular epiphysis.

Transition from atherosclerosis to aortic aneurysm in humans coincides with an increased expression of RAS components

While the renin-angiotensin system (RAS) is widely recognized to be involved in atherosclerosis, its potential role in the progression from atherosclerotic lesions to abdominal aortic aneurysm (AAA) is poorly understood. The present study aimed to investigate which components of the RAS may render the atherosclerotic aorta aneurysmatic. The expression of renin, prorenin/renin receptor, angiotensinogen, AT1- and AT2 receptors, cathepsin D, cathepsin G and chymase was examined by immunoblotting and immunohistochemistry in human atherosclerotic, aneurysmatic and healthy aortic tissues obtained from patients undergoing elective repair or at autopsy. AT1- and AT2 receptor mRNA expression was determined using quantitative real-time RT-PCR. All investigated local RAS components were up-regulated in atherosclerotic as compared to healthy tissues. AAA compared to atherosclerosis was characterized by a further increase in the expression of all RAS components except for the AT2 receptor. Cathepsin D was exclusively up-regulated in AAA. Most RAS components co-localized with infiltrating leukocytes or mast cells pointing to their contribution to inflammatory processes. Due to their proteolytic features, some RAS components (cathepsin D and cathepsin G and chymase) may contribute to AAA formation by accessory mechanisms. Taken together, our data suggest that in humans, RAS activation is not just a key-player in the pathogenesis of atherosclerosis, but that a further increasing activation may be involved in the transition from atherosclerosis to AAA.