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Biomedical subjects

J Schmidt

Publications and source records attributed to J Schmidt.

At least 73 records · Page 4Linked to original sources
PubMed2004

Light fields for minimal invasive surgery using an endoscope positioning robot.

OBJECTIVES: To generate a fast and robust 3-D visualization of the operation site during minimal invasive surgery. METHODS: Light fields are used to model and visualize the 3-D operation site during minimal invasive surgery. An endoscope positioning robot provides the position and orientation of the endoscope. The a priori un-known transformation from the endoscope plug to the endoscope tip (hand-eye transformation) can either be determined by a three-step algorithm, which includes measuring the endoscope length by hand or by using an automatic hand-eye calibration algorithm. Both methods are described in this paper and their respective computation times and accuracies are compared. RESULTS: Light fields were generated during real operations and in the laboratory. The comparison of the two methods to determine the unknown hand-eye transformation was done in the laboratory. The results which are being presented in this paper are: rendered images from the generated light fields, the calculated extrinsic camera parameters and their accuracies with respect to the applied hand-eye calibration method, and computation times. CONCLUSION: Using an endoscope positioning robot and knowing the hand-eye transformation, the fast and robust generation of light fields for minimal invasive surgery is possible.

Algorithms↗
PubMed2003

[Surgical accident expert evaluation of dislocation of the cervical vertebrae].

Evaluation of a cervical-vertebra distortion, respectively with prolonged progress and/or degenerative concomitant symptoms, places high demands on the preparatory clerk as well as on the executing adviser. Complete file preparation can best be described as the task of a "hunter-gatherer". The adviser has to determine the actual accident sequela on the basis of delineated and documented complaints with investigative meticulousness. Additionally, non-surgical evidence has to be introduced and treated specifically.

Cervical Vertebrae↗
PubMed2003

Accuracy of diagnostic laparoscopy for early diagnosis of abdominal complications after cardiac surgery.

BACKGROUND: In the early postoperative period after major cardiac surgery using extracorporal circulation, abdominal complications can have serious consequences with a mortality rate of up to 70%. Early diagnosis and the timely institution of therapy are the most important factors to improve the outcome; however, clinical evaluation of the abdomen is difficult in these patients. Diagnostic laparoscopy is a minimally invasive procedure with low procedure-associated morbidity, even in critically ill patients. The aims of our study were to investigate the safety of laparoscopy in critically ill patients suspected to have intraabdominal pathology following cardiac surgery and to evaluate the accuracy of diagnostic laparoscopy compared to laparotomy in this setting. METHODS: A total of 17 patients were included (13 male, four female, age 52-80 years) in the early (3-30 days) postoperative period after cardiac surgery using extracorporal circulation (10 ACVB, four valve replacement, one aorto-coronary-venous-bypass (ACVB)+ valve replacement, two cardiac transplantation). Clinical and laboratory findings included distended abdomen (17 of 17), elevated white blood cells (12 of 17), elevated C-reactive protein (CRP) (13 of 17), and elevated lactate levels (11 of 17). The decision to perform laparotomy was taken in all patients on the basis of their clinical condition. Diagnostic laparoscopy was always performed immediately before laparotomy. The laparoscopic findings were then compared to the laparotomy findings. RESULTS: In one patient, laparoscopy showed no abnormal findings, this was confirmed on laparotomy. Five patients were found to have massive distension of the large bowel without ischemia on both laparoscopy and laparotomy. Colonic ischemia of the right hemicolon was found laparoscopically in six patients, which was confirmed in all cases by open resection and histological workup. Three patients suffered from acute cholecystitis, which was correctly diagnosed by laparoscopy in all cases. In one patient, laparoscopy revealed fibrinous peritonitis without other findings. Open exploration failed to identify the cause of the peritonitis in this patient. Laparoscopy showed no pathological findings in one patient, but laparotomy then revealed necrotizing pancreatitis confined to the lesser sac. There was one laparoscopy-associated intraoperative complication (6%) in this series. CONCLUSIONS: Diagnostic laparoscopy is a minimally invasive procedure that can be performed at low intraoperative risk in critically ill patients and has a high sensitivity (94%) for the correct diagnosis of intraabdominal complications after major cardiac surgery. These results suggest that bedside laparoscopy should be considered for all patients with equivocal abdominal symptoms in this setting.

Aged↗
PubMed2003

Histological findings of the femoral bone after cement removal in hip revision. An experimental study of cadaver femurs with two different cement removal procedures.

Cement removal in hip revision arthroplasty is often a time-consuming procedure, lengthy and tedious. Intraoperative bone damage is one of the more common complications. In the present study, the conventional cement removal method is compared with a new method by means of a histological study concerning potential negative effects to cortical or spongious bone. Histological studies on human cadaver femurs demonstrate no deleterious effects on the endosteal bone when cement was removed with this new device. The ballistically driven chiselling system (OrthoClast) is safe to the bone stock and shows no increased risk of bone damage over the conventional technique with mallet and chisel.

Arthroplasty, Replacement, Hip↗
PubMed2003

Comparison of biomaterials in the early postoperative period.

BACKGROUND: Laparoscopic hernia repair necessitates the use of biocompatible materials. A prospective, double-blind study was conducted to compare two different polypropylene meshes. METHODS: The study included 40 men with primary inguinal hernia undergoing transabdominal preperitoneal polypropylene mesh repair. In 20 of these men, a monofile, heavy-weight, rigid mesh was implanted (group A), and in the remaining 20 men, a smooth, heavy-weight variant of polypropylene mesh was implanted (group B). Complications, pain development, inability to work, physical conditions, testicular volume, and blood circulation were documented. RESULTS: Reconvalescence in group A was slower than in group B. In group A, the postoperative values of the visual scales for pain development were higher; inability to work was 7.3 days longer; urologic disorders were worse; activities of everyday life were more reduced; and SF-36 data showed a significant reduction of physical problems ( p < 0.05). CONCLUSIONS: The polypropylene mesh variant seems to be more compatible with the human organism than conventional mesh. Not only the material, but also the structure seems to influence the comfort of the mesh.

Aged↗
PubMed2003

Laparoscopically assisted colectomy and ileoanal pouch procedure with and without protective ileostomy.

BACKGROUND: Apart from an obviously better cosmetic situation, there is controversy on the actual benefit of laparoscopic and laparoscopically assisted techniques in restorative proctocolectomy. The need for a protective ileostomy remains unclear. METHODS: Fifty-nine consecutive patients with ulcerative colitis and familial polyposis were included in this prospective cohort study. The colon was mobilized laparoscopically with a four-trocar technique, facilitating vascular dissection, rectal resection, and ileoanal pouch construction to be done through a Pfannenstiel incision. A protective ileostomy was constructed only in patients where the operation was difficult or where the anastomosis was under tension. Intra- and postoperative data were recorded; statistical analyses were performed by exact logistic regression. RESULTS: Laparoscopic mobilisation was successful in 54 patients (91.2%). Two patients had to be primarily converted because of exceeding the set time limit; 3 other patients had to have an additional median laparotomy. These 5 patients all had an increased body mass index (BMI), which was a statistically significant risk factor for failure of the laparoscopic technique. 18.6% of patients developed major complications (n = 11). Nine patients required secondary ileostomies; all of them either were under high dose immunosuppressants (n = 5) or had an increased BMI (average 28.42 kg/m2). Failure of the laparoscopic technique was associated with major complications. CONCLUSION: Laparoscopically assisted restorative proctocolectomy is technically feasible; an increased BMI is a relevant risk factor for failure. The minimally invasive approach probably does not reduce the need for a protective ileostomy in selected patients. The selection criteria for the addition or omission of a protective ileostomy in minimally invasive restorative proctocolectomy remain to be clearly defined.

Adenomatous Polyposis Coli↗
PubMed2003

Detoxification of ferulic acid by ectomycorrhizal fungi.

The ectomycorrhizal fungi Laccaria amethystina and Lactarius deterrimus grown in liquid culture were used to study the fate of added ferulic acid. Laccaria amethystina degraded ferulic acid to the major metabolite vanillic acid. The intermediate vanillin was not detected. Lactarius deterrimus showed a completely different detoxification pattern. Two dimers and one trimer of ferulic acid could be identified as polymerization products of this fungus. A bioassay of the possible biological activities of ferulic acid and vanillic acid on these fungi revealed that vanillic acid was less toxic than ferulic acid for Laccaria amethystina but that both phenolic acids were toxic for Lactarius deterrimus. The results are discussed with respect to ectomycorrhizal fungal growth in the organic layer of forest soils and between living root cells of ectomycorrhizas.

Agaricales↗
PubMed2003

[Urological symptoms after laparoscopic hernia repair. Reduction with a variant of polypropylene mesh].

In the context of a prospective, randomized, controlled double-blind study concerning a reduction of postoperative, urogenital affections after laparoscopic hernia repair using a polypropylene mesh, laparoscopic polypropylene implantation was performed in 40 male patients. Twenty patients received a heavyweight, rigid polypropylene mesh (group A) and the remainder a heavyweight, but softer polypropylene mesh (group B). Questionnaires were used to assess the severity of pain, impairment of sexual life, appearance of urogenital affections, and general condition. On the 3rd postoperative day, testicle blood circulation and testicle volumes were documented by ultrasound, and a congestion of the plexus pampiniformis was excluded by ultrasound with 5 MHz. Starting in the 1st postoperative week, a prevalence of affections such as testicular sensitivity to touch, pain upon ejaculation, and a pulling sensation during urination became apparent in group A. In the 12th postoperative week, 20% in group A still described testicular sensitivity to touch and 10% pain upon ejaculation and a pulling sensation during urination but only 5% in group B. It is essential to reduce urogenital affections after laparoscopic hernia repair by strict indications and appropriately adapted polypropylene meshes.

Aged↗
PubMed2003

[Central case management in surgery].

Up to now, in most surgical departments there has been no central patient management coordinating the admission, the diagnostic work-up, and the surgical procedures of patients with the resources available in the hospital. In future, however, it will be essential for surgical departments to establish such a central patient management, not only in view of the importance of patient-oriented medicine but also considering the planned introduction of diagnosis related groups. A central patient management will reduce preoperative and overall length of stay through adequate organisation and communication structures. In addition, a central patient management will make optimal use of the available resources in terms of operation rooms and hospital beds. In this article, we will present our basic concept of a central patient management in a surgical university department.

Diagnosis↗
PubMed2003

Genomics and proteomics in cancer.

Cancer development is driven by the accumulation of DNA changes in the approximately 40000 chromosomal genes. In solid tumours, chromosomal numerical/structural aberrations are common. DNA repair defects may lead to genome-wide genetic instability, which can drive further cancer progression. The genes code the actual players in the cellular processes, the 100000-10 million proteins, which in (pre)malignant cells can also be altered in a variety of ways. Over the past decade, our knowledge of the human genome and Genomics (the study of the human genome) in (pre)malignancies has increased enormously and Proteomics (the analysis of the protein complement of the genome) has taken off as well. Both will play an increasingly important role. In this article, a short description of the essential molecular biological cell processes is given. Important genomic and proteomic research methods are described and illustrated. Applications are still limited, but the evidence so far is exciting. Will genomics replace classical diagnostic or prognostic procedures? In breast cancers, the gene expression array is stronger than classical criteria, but in endometrial hyperplasia, quantitative morphological features are more cost-effective than genetic testing. It is still too early to make strong statements, the more so because it is expected that genomics and proteomics will expand rapidly. However, it is likely that they will take a central place in the understanding, diagnosis, monitoring and treatment of (pre)cancers of many different sites.

Cell Transformation, Neoplastic↗
PubMed2003

In vivo assessment of angioarchitecture and microcirculation in experimental liver cancer: a new model in rats.

The rising incidence of unresectable hepatocellular malignancies remains a therapeutic challenge. Little is known about the mechanisms of angiogenesis and immunological aspects of liver tumor vessels. The aim of this study was to investigate hepatic and tumor microcirculation and leukocyte-endothelium interaction by means of intravital microscopy in a rat model of hepatocellular carcinoma. Off-line analysis showed that the angioarchitecture as well as blood flow velocity in liver cancer is heterogeneous. The leukocyte-endothelium interaction is significantly reduced compared to normal liver tissue. The data suggest that the main mechanism is a reduced expression of adhesion molecules demonstrating an effective immune escape mechanism of this tumor. The model represents a useful experimental tool to explore angiogenesis inhibition or immunological therapeutic strategies in experimental liver cancer.

Animals↗
PubMed2003

Expression of HLA class I/II antigens and T cell immune response in human neuroendocrine tumors of the pancreas.

Peptide presentation by HLA class I and II antigens regulates specific antigen recognition by T cells. The present study aimed to investigate T cell infiltration and its relation to HLA antigen expression in pancreatic neuroendocrine tumors. Fresh tissue samples were collected from five insulinomas and six other neuroendocrine tumors (one gastrinoma, one glucagonoma, two carcinoid, and two neuroendocrine carcinomas). Normal pancreatic and splenic tissue samples were used as controls. Investigation of infiltrating lymphocyte populations, as well as staining of HLA class I and II antigens, were performed by standard immunohistochemistry. The majority of investigated tumors demonstrated an intratumoral infiltration by CD3+, CD4+ and CD8+ T cells that was significantly higher than in normal pancreatic islets. Only a minority of tumor-infiltrating T cells showed the CD45RO+ phenotype. The expression of HLA class I antigen was altered in 10 of 11 tumors. A loss of beta-2microglobulin represented the most frequent type of alteration to HLA class I expression, although the total loss of HLA class I was found in only one case of neuroendocrine carcinoma. HLA class II molecules were expressed by endothelial and lymphoid cells and not by tumor cells. In conclusion most neuroendocrine pancreatic tumors induce a T cell mediated immune response resulting in an intratumoral infiltration with CD3+, CD4+ and CD8+ T cells. Loss of beta-2microglobulin is a frequent alteration in these tumors, which may influence the normal function of the HLA class I antigen complex. In contrast to malignant tumors of the exocrine pancreas, expression of HLA class II was absent in neuendocrine pancreatic tumor cells.

Antigen Presentation↗
PubMed2003

[Individualized outcome measurement -- a comparison between prospective and retrospective problem marking in psychosomatic rehabilitation].

This article reports on a questionnaire concerning individual problems in psychosomatic rehabilitation. A sample of 858 patients answered the questions at the beginning and on a one year catamnestic measurement. First, the frequency of occurrence of several symptoms was asked. Second, the rehabilitants were asked to indicate for each symptom if it was an important problem before treatment. This procedure of identifying problems was done at the beginning (prospective marking) and also at the one year follow up (retrospective marking). The questionnaire allows to compute eight subscales and one global scale regarding all items (classical approach). Frequency of occurrence decreased with an average effect size (ES) of 0.56 on the global scale. In the next step, measurement was individualized by regarding only items which were marked as relevant problem. By prospective marking, effect size was 1.32. By retrospective marking, no growth of effect size in comparison to the classical approach was found (ES = 0.56). The results indicate that the prospective approach of identifying problems is the better way of individualizing measurements. Moreover, the impact of individual problem definition on outcome was demonstrated.

Adjustment Disorders↗
PubMed2003

Angiogenesis inhibition with TNP-470, 2-methoxyestradiol, and paclitaxel in experimental pancreatic carcinoma.

INTRODUCTION: Inhibition of tumor angiogenesis is a novel therapeutic modality for various malignancies. AIM: To investigate the effect of different antiangiogenic agents (TNP-470, 2-methoxyestradiol, and paclitaxel) on growth and neovascularization of experimental pancreatic cancer. METHODOLOGY: In 25 male Lewis rats, tumor induction was achieved by orthotopic and subcutaneous tumor fragment implantation of ductlike pancreatic cancer DSL6A. Four weeks after tumor implantation, the animals were randomly treated with TNP-470, 2-methoxyestradiol, or paclitaxel. After 2 weeks of antiangiogenic therapy, total tumor volume, vital tumor surface, vascular density, and apoptosis were measured. RESULTS: Total tumor volume and vital tumor surface were not significantly different in any of the treatment groups. Similarly, vascular density and apoptosis were not altered by treatment with the various angiogenesis inhibitors at the specific doses used. CONCLUSION: We conclude that in contrast to many earlier studies, angiogenesis inhibition by a single-drug application and by the doses used in the present model did not reveal a favorable therapeutic effect on pancreatic cancer DSL6A. The combination of different angiogenesis inhibitors or higher doses might be more effective.

2-Methoxyestradiol↗
PubMed2003

Comparison of talinolol and atenolol effects on blood pressure in relation to lipid and glucose metabolic parameters. Results from the TALIP study.

AIMS: The primary objective of this double-blind, randomized, parallel-group study was to compare the influence ofthe selective beta1-receptor antagonists talinolol (100 mg) and atenolol (50 mg) on the lipid metabolism in hyperlipemic patients with mild to moderate hypertension after 12 weeks of treatment. As a secondary endpoint, the influence of the drug on blood pressure, pulse rate as well as glucose metabolism were examined. Furthermore, pharmacokinetic parameters were assessed. PATIENTS: Of the 198 patients recruited for the study, 166 were randomized to receive atenolol (n = 83) or talinolol (n = 83) for up to 12 weeks, 149 patients received the study medication for up to 48 weeks under double-blind conditions. RESULTS: There was no difference between the antihypertensive effect of both beta1-selective antagonists in patients with mild to moderate hypertension. No clinically relevant differences between the 2 drugs were observed for LDL cholesterol, HDL cholesterol, total cholesterol and triglycerides in the rather low doses given. However, there was evidence for a decrease in LDL cholesterol following treatment with talinolol, but not following treatment with atenolol, in patients with the highest initial blood pressure and in those with normalized blood pressure after 12 weeks of treatment. Parameters of glucose metabolism were not adversely affected by both drugs. Stable pharmacokinetics were observed over the 12-week administration, and steady state conditions were achieved after a 1-week treatment with both active compounds in the target population. Data indicate that once-a-day dosing can be performed with less fluctuation between peak and trough for talinolol in comparison to atenolol. Both treatments were well tolerated.

Administration, Oral↗
PubMed2002

[Influence of ACE inhibitor spirapril on left ventricular hypertrophy].

BACKGROUND: In view of the prevalence of left ventricular hypertrophy (LVH) in patients with essential hypertension, (15-30%), with an increased risk (2-4 x) of developing myocardial infarction, heart failure or malignant arrhythmia, possibly even leading to sudden cardiac death, effective reversal of LVH is a major aim of treatment. For this purpose, angiotensin-converting enzyme (ACE) inhibitors have proved to be most suitable. METHOD: In an open bicentric study involving 37 hypertensive patients with LVH confirmed by echocardiography, the effect of spirapril in reversing the left ventricular mass index (LVMI) and diastolic left ventricular wall thickness was investigated after 3 and 6 months. RESULTS: The LVMI decreased by 14.7% after 3, and by 27.3% after 6 months, irrespective of whether spirapril was given alone or in addition to other antihypertensive pre-medication. The results may be due to the proven 24-hour effect of spirapril in conjunction with the very long half-life.

Adult↗
PubMed2002

Genetic analysis of the biosynthesis of the pyrrole and carbamoyl moieties of coumermycin A1 and novobiocin.

The aminocoumarin antibiotic coumermycin A(1) contains a central and two terminal pyrrole moieties. The coumermycin gene cluster in Streptomyces rishiriensis contains three genes (couN3, couN4 and couN5) that show sequence similarity to genes involved in the biosynthesis of the pyrrole moieties of pyoluteorin in Pseudomonas fluorescens and of undecylprodiginine in S. coelicolor. The gene couN3, which codes for a putative L-prolyl-S-PCP dehydrogenase, and the gene couN4, which encodes a putative L-prolyl-AMP ligase, were disrupted using in-frame deletion and insertional inactivation, respectively. HPLC analysis of culture extracts showed that formation of the two terminal pyrrole moieties was abolished in the couN3 (-) und couN4 (-) mutants. The mutants accumulated coumermycin D, which contains only the central pyrrole moiety. This result not only confirmed the involvement of couN3 and couN4 in the biosynthesis of the terminal pyrrole-2-carboxylic acid moieties of coumermycin A(1), but also indicated, for the first time, that the central 3-methylpyrrole-2,4-dicarboxylic acid unit of the coumermycins is formed by a biosynthetic pathway that differs from that used to assemble the terminal pyrrole moieties. novN, a putative carbamoyl transferase gene from the gene cluster for novobiocin biosynthesis in S. spheroides was expressed in the couN3 (-) mutant. This led to the formation of bis-carbamoylated coumermycin D, a novel compound of the coumermycin series.

Aminocoumarins↗