Biomedical subjects

C Kuhlmann

Publications and source records attributed to C Kuhlmann.

5 recordsLinked to original sources

PubMed2005

[Evaluation of potential risks of abrasive water jet osteotomy in-vivo].

Since the 80's the water jet scalpel is an established tool in some surgical fields. It is used in particular in visceral surgery for preparation of parenchymatous organs. By the addition of biocompatible abrasives, this technique is able to effectively machine hard biological tissues. Free defined cutting geometries can be realised in a non contact process. Therewith this method has crucial advantages compared to conventional osteotomy techniques and gives new impulses to the development in endoprosthetics and correction osteotomies of hollow bones. In the presented work the new developed abrasive water injection jet (AWIJ) was used the first time for in-vivo osteotomies. Aim of this study was the detection of potential thrombembolic effects and wash in effects of the cutting fluid. Hollow bones of the fore and hind leg of 20 house pigs were treated with the new cutting technique. Intraoperative documentation of relevant vital parameters was performed by a multi monitoring system. Thrombembolic effects during the osteotomy were detected by transthoracic Doppler ultrasonography and transesophagale echocardiography. The hollow bones were prepared in consideration of the vascularisation's protection especially in respect to the venous flow. Thrombembolic effects with temporary haemodynamic respectively respiratory consequences could be detected exclusively by using the so called "3-component jet", which consists of 90 vol % of air. The usage of an abrasive suspension enables the airfree dosing of dry soluable abrasives. Thrombembolic effects could not be monitored in this case. Intramedullary fluid in-wash effects as well as resulting electrolytic disorders could not be proven. For abrasive waterjet osteotomies with 3 component jet a relevant risk of thrombembolic effects could be shown. This knowledge has also to be considered for abdominal and neurosurgical applications in the future. Due to the usage of an abrasive suspension this risk can fully be avoided.

Animals↗

PubMed2001

Hierarchic patterning: architectures beyond 'giant molecular wheels'.

Based on symmetry breaking steps under one-pot conditions, simple molybdenum oxide-based building blocks initially assemble to 'giant molecular wheels' in a fast process followed by further slower assembly processes leading stepwise to more complex mesoscopic architectures including spherical ones and finally to those with a size larger than 500 nm.

Journal Article↗

PubMed1997

Reproducibility of stress echocardiography using intravenous injection of ultrasound contrast agent (BY 963).

UNLABELLED: Despite the widespread use of stress echocardiography, its reproducibility is still limited by high interobserver variability. Therefore, the purpose of the present study was to improve the reproducibility of a stress (exercise) echocardiography using a new transpulmonary ultrasound agent (BY 963). Stress echocardiography was performed in 12 healthy volunteers with suboptimal endocardial border delineation during exercise echocardiography. A special 45 degrees lateral tilted bike stress echocardiography table was used for exercise testing. Echocardiographic images were recorded on-line at rest and during exercise on a video tape and additionally digitized on-line on a stress echo computer. End-diastolic (EDVml), end-systolic (ESVml) volume and ejection fraction (EF%) were estimated in the 4-chamber view. The measurements were performed before and after injection of 2.5 ml and 5 ml BY963 at rest and in maximal exercise. A new contrast agent (BY 963) leads to a sufficient contrast effect for the left ventricular cavity after intravenous administration and permits a good delineation of left the endocardial border. The interobserver variability was determined using blinded investigation by two observers. The correlation of EDV and ESV determination at rest was r = 0.68/0.33, after 2.5 ml BY 963 r = 0.97/0.93 and after 5 ml BY 963 r = 0.90/0.93. The correlation for EDV and ESV during exercise was r = 0.52/0.33, after 2.5 ml BY 963 r = 0.88/0.80 and after 5 ml BY 963 r = 0.95/0.92. At rest mean EF without contrast was 61 +/- 6%/67 +/- 7% (r = 0. 130), after 2.5 ml BY 963 i.v. 69 +/- 8%/72 +/- 7% (r = 0.82) and after 5 ml BY 963 i.v. 73 +/- 8%/73 +/- 8% (r = 0.98%) respectively. In exercise, mean EF without contrast was 68 +/- 8%/70 +/- 6 (r = 0.013), after 2.5 ml BY 963 83 +/- 6%/81 +/- 5 and after 5 ml 83 +/- 4%/82 +/- 3 (r = 0.86). SUMMARY: The estimation of the end-systolic volume in exercise will be improved significantly and the estimated EF values will be higher compared to EF values obtained without contrast application. Transpulmonary contrast echocardiography for analysis of left ventricular volumes and ejection fraction can be routinely used in stress echocardiography. Intravenous administration of BY 963 improves the reproducibility of quantitative analysis of left ventricular function in healthy volunteers. Further studies in patients with cardiac diseases are required to corroborate this observation.

Adult↗

PubMed1995

Investigations on autologous T-cells for adoptive immunotherapy of AIDS.

We report on the preclinical results of an immunotherapeutic approach of AIDS mediated by ex vivo propagated CD4+ and CD8+ T-cells. A mean yield of 6.23 x 10(9) lymphocytes, containing 1.82 x 10(9) CD4+, 3.23 x 10(9) CD8+ T-lymphocytes and 8.39 x 10(6) CD34+ peripheral blood progenitor cells (PBPC) were be obtained by continuous flow cytapheresis (CFC) in 15 asymptomatic HIV infected patients (CD4-count > 350/mm3). The CD4/CD8 ratio (mean: 0.53, SD: +/- 0.15) in the cell concentrates reflected the distribution of the circulating lymphocyte subsets in vivo. Absolute lymphocyte counts decreased at a mean of 404/microliter (25%) immediately after CFC but were replaced from the extravascular pool within one hour. Neither the CD4/CD8 ratio nor p24-antigen and neopterin levels did change significantly after cell separation. No alteration of the number of proviral DNA copies (1/10(3)-1/10(6)) could be detected in peripheral T-helper cells by semiquantitative PCR after lymphapheresis. Cells were cryopreserved in liquid nitrogen without substantial loss of viability or function. Ex vivo propagation of T-cells in a strictly autologous manner in the presence of PHA + IL-2 for 14d resulted in a 50-fold expansion rate (140-fold in healthy controls, p < 0.001). Viral replication could be controlled but not completely eliminated by cocultivation with autologous CD8+ T-lymphocytes as measured by limiting dilution nested PCR (NPCR). The expanded cells showed the typical phenotype of highly activated memory type T-lymphocytes (CD3+ CD45RO+ CD25+ HLA-DR+). The distribution of CD4+ and CD8+ T-cells did not reveal significant changes before and after culture indicating that both subsets were equally expanded. Functionally important membrane or intracellular epitopes which were found to be decreased in HIV infected subjects (CD7, CD55, CD59) before culture were reconstituted after ex vivo propagation of T-cells. The functional importance of the up-regulation of complement regulating epitopes (CD55, CD59) after culture could be proven by a significant inhibition of cytolysis of T-cells in the presence of autologous complement. The majority (75%) of expanded CD8+ T-cells stained positive with mAb TIA-1 which is directed to intracellular granules within cytotoxic T-cells. Furthermore, programmed cell death of expanded T-cells could be prevented by cocultivation with fibroblasts which are believed to secrete a cytokine pattern preventing activated T-cells from apoptosis after withdrawal of IL-2 and other stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)

AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Efficacy of a benzalkonium chloride-impregnated central venous catheter to prevent catheter-associated infection in cancer patients.

BACKGROUND: This study was performed to determine the efficacy of a benzalkonium chloride-impregnated central venous catheter (CVC) in preventing catheter-related infection in patients suffering from malignant diseases and undergoing chemotherapy. METHODS: A randomized, prospective clinical trial was carried out to compare the incidence of catheter-related colonization and catheter-related bacteremia using an antiseptic-impregnated CVC (n = 25) with that using a standard triple-lumen CVC (n = 25). RESULTS: All patients were treated with intensive chemotherapy for acute leukemia (n = 28), lymphoma (n = 17) or solid tumors (n = 5). Both study groups presented with similar data in regards to age, insertion site, duration of catheterization and neutropenia period during catheterization, demonstrating a comparable risk for catheter-related colonization. Suspicion of infection led to explantation in 14 versus 15 cases. Catheter-related colonization was proven in 4 cases (16%) and catheter-related bacteremia was observed only once (4%) in both groups. Statistical testing showed no significant differences between the study and control group. CONCLUSIONS: The rate of catheter-related colonization was lower than suspected in this high-risk patient group. The use of benzalkonium chloride-impregnated CVC failed to decrease the incidence of catheter-related colonization and bacteremia in patients with a high risk of infectious complications.

Adult↗