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Biomedical subjects

Thomas Schmid

Publications and source records attributed to Thomas Schmid.

At least 19 recordsLinked to original sources
PubMed2007

A comparison of outcomes after robotic open extended thymectomy for myasthenia gravis.

OBJECTIVE: The aim of this study was to analyze the effect of the surgical approach on surgical and neurologic outcomes after extended thymectomy for myasthenia gravis. METHODS: A retrospective analysis of the institutional extended thymectomies for myasthenia gravis within the last decade was performed. Patients of group A (open access by total median sternotomy; n=10; 1996-2002) and of group B (video assisted thoracoscopic surgery approach with the da Vinci robotic system; n=9; 2003-2006) did not differ with regard to gender distribution, age, body mass index, American Association of Anaesthetists score and Osserman classification of myasthenia gravis. Primary endpoints were surgical complications and the symptomatic/neurologic outcome of the extended thymectomy. Secondary endpoints were operating times and hospital stay. RESULTS: Median follow-up was 74+/-23 months in group A and 13+/-10 months in group B. Surgical complications occurred in 4 patients in group A (requiring 2 re-interventions) and in 1 patient in group B (p<0.05). The median dose of Pyridostigminbromid was reduced 3 and 6 months postoperatively in group A to 80% and 60% of the preoperative level and in group B to 66% and 60% of the preoperative level, respectively. Within the first postoperative year all patients of group B had an improvement of their disease whereas 2 patients of group A did not benefit from thymectomy or had a worsening of symptoms. Operating times were significantly shorter in group A (110 (42-152) min vs 154 (94-312) min, p<0.05), hospital stay was significantly shorter in group B (5 (4-15) vs 10 (10-23) days, p<0.05). CONCLUSIONS: The results of this small series favour the robotic approach for extended thymectomy for myasthenia gravis in respect of both surgical and early neurologic outcome. However, prospective randomized trials are required to prove a general validity.

Female↗
PubMed2006

Severe graft rejection, increased immunosuppression, and active CMV infection in renal transplantation.

Associations between active cytomegalovirus (CMV) infection, graft rejection, rejection therapy, and clinical signs and symptoms have been shown repeatedly. However, the causes and the sequence of events remain an area of debate. Two hundred twenty five patients with cadaveric renal transplant were included in the present study. Clinical signs and symptoms, and the development of active CMV infections were recorded during the first 3 months after renal transplantation. CMV monitoring by pp65-antigenemia was performed followed by preemptive antiviral therapy. Delayed graft function and severe graft rejection followed by anti T-cell antibody therapy was associated with the development of active CMV infection. In contrast, the induction therapy with anti-T-cell antibodies was not associated with more active CMV infections. Post-transplant morbidity determined by fever, pneumonia, and duration of hospital stay was increased significantly in patients with active CMV infection. However, in times of preemptive antiviral therapy an increased morbidity occurred in association with severe graft rejection and not with active CMV infection alone. In patients with renal transplantation and preemptive antiviral therapy, the morbidity was no more influenced by the CMV serostatus although the prevalence of active CMV infection was obviously different between CMV exposed (D+/R+,D+/R-, D-/R+) and unexposed (D-/R-) patients. Severe graft rejection and increased immunosuppression could stimulate cooperatively active CMV infections whereas immunosuppression alone may not be as effective. Prevention of severe graft rejection may be important to decrease early post-transplant morbidity and also the development of active CMV infections after renal transplantation.

Adult↗
PubMed2006

Indicators of activity-friendly communities: an evidence-based consensus process.

BACKGROUND: Regular physical activity, even at modest intensities, is associated with many health benefits. Most Americans, however, do not engage in the recommended levels. As practitioners seek ways to increase population rates of physical activity, interventions and advocacy efforts are being targeted to the community level. Yet, advocates, community leaders, and researchers lack the tools needed to assess local barriers to and opportunities for more active, healthy lifestyles. Investigators used a systematic review process to identify key indicators of activity-friendly communities that can assess and improve opportunities for regular physical activity. METHODS: Investigators conducted a comprehensive literature review of both peer-reviewed literature and fugitive information (e.g., reports and websites) to generate an initial list of indicators for review (n=230). The review included a three-tiered, modified Delphi consensus-development process that incorporated input of international, national, state, and local researchers and practitioners from academic institutions, federal and state government agencies, nonprofit organizations, and funding agencies in public health, transportation, urban planning, parks and recreation, and public policy. RESULTS: Ten promising indicators of activity-friendly communities were identified: land use environment, access to exercise facilities, transportation environment, aesthetics, travel patterns, social environment, land use economics, transportation economics, institutional and organizational policies, and promotion. CONCLUSIONS: Collaborative, multidisciplinary approaches are underway to test, refine, and expand this initial list of indicators and to develop measures that communities, community leaders, and policymakers can use to design more activity-friendly community environments.

Consensus↗
PubMed2006

Functional redundancy of NSCL-1 and NeuroD during development of the petrosal and vestibulocochlear ganglia.

To study the role of different members of the bHLH gene family for sensory organ development we have generated NSCL-1 and NeuroD compound-mutant mice. Double homozygous animals were characterized by a more severe reduction of the petrosal and vestibulocochlear ganglia than NeuroD-knockout mice. The more severe reduction of the petrosal and vestibulocochlear ganglia in double-knockout mice indicates overlapping functions of the two genes during neuronal development. Interestingly, we also found that the two genes are jointly regulated by thyroid hormone during sensory hair cell development. We further present a detailed expression analysis of NSCL-1 and NSCL-2 during sensory neuron development. NSCL-1 expression was detected in all developing cranial ganglia including the petrosal and vestibulocochlear ganglion, in inner and outer hair cells of the organ of Corti and in hair cells of the vestibular system. Expression domains in other sensory structures include the retina, Merkel cells of the developing skin and sensory cells of the tongue. The expression of NSCL-2 was restricted to developing cranial ganglia, the retina and the vestibular nerve. Both NSCL-1 and NSCL-2 genes are active only in postmitotic neurons, indicating a role for neuronal cell migration and/or differentiation within the sensory system.

Animals↗
PubMed2006

High rate of molecular alteration in histologically tumour-free bronchial epithelium of NSCLC patients detected by multicolour fluorescence in situ hybridisation.

Detection of molecular abnormalities could provide an essential tool for the diagnosis of non-small cell lung cancer (NSCLC) and defining patients at risk for early relapse. Fluorescence in situ hybridisation (FISH) targeting 17 gene loci was applied to determine the frequency of molecular alteration in NSCLC probes and adjacent tumour-free bronchial epithelium. FISH was performed on fresh frozen specimens from 76 patients with histologically confirmed NSCLC and 54 specimens of adjacent tumour-free tissue. Routine autopsy lung tissue probes from 7 cancer-free patients served as a control group. Locus-specific (3p14.2, 3p21.2, 3p21.3, 3p25.3, 5p15.2, 7p12, 8q24.12, 9p21, 13q14, and 17p13.1) as well as centromere probes (4, 6, 7, 9, 11 and 16) were used. Molecular alterations using FISH on interphase nuclei were detected in 100% of NSCLC tumour specimens and 89% of microscopically tumour-free tissues of NSCLC patients. In histologically 'normal' epithelium, the most frequent alterations were seen with locus-specific probes for 3p14.2, 3p.21, 3p21.3, 3p25.3 and 7p12 and centromere-specific probes 11 and 16 (12-93%). As expected, the majority of genetic alterations seen in 'premalignant' specimens were found in the correlating tumour probes. None of the tested parameters revealed prognostic significance in univariate Cox analysis. FISH analysis, performing multicolour strategies, demonstrated its power in detecting genetic abnormalities in NSCLC specimens and even in tumour-free sections of tumour patients.

Adult↗
PubMed2005

The da Vinci robotic system for general surgical applications: a critical interim appraisal.

PRINCIPLES: The recently introduced robotic surgical systems were developed to overcome the limitations of conventional minimally invasive surgery. We analyse the impact of the da Vinci robotic system on general surgery. METHODS: The da Vinci operating robot is a telemanipulation system consisting of a surgical arm cart, a master console and a conventional monitor cart. Since its purchase in June 2001, 128 patients have undergone surgery using the da Vinci robot in our department. The mean age of the 78 female and 50 male patients was 52 (range 18-78) years. RESULTS: The procedures included 29 cholecystectomies, 16 partial fundoplications, 16 extended thymectomies, 14 colonic interventions, 10 splenectomies, 10 bariatric procedures, 7 hernioplasties, 6 oesophageal interventions, 5 adrenalectomies, 5 lower lobectomies, 4 neurinomectomies and 6 others. 122 of 128 procedures (95%) were completed successfully with the da Vinci robot. Open conversion proved necessary in 4 patients due to surgical problems, and two other procedures were completed by conventional laparoscopy due to robot system technical errors. 30-day mortality was 0%, one redo-operation was necessary and two lower complications not requiring surgical re-intervention occurred. The resection margins of all tumour specimens were histologically tumour free. CONCLUSIONS: Various general surgical procedures have proved feasible and safe when performed with the da Vinci robot. The advantage of the system is best seen in tiny areas difficult of access and when dissecting delicate, vulnerable anatomical structures. However, in view of longer operating times, higher costs and the lack of adequate instruments, robotic surgery does not at the moment represent a general alternative to conventional minimally invasive surgery.

Adolescent↗
PubMed2005

Photoacoustic spectroscopy for process analysis.

Photoacoustic spectroscopy (PAS) is based on the absorption of electromagnetic radiation by analyte molecules. The absorbed energy is measured by detecting pressure fluctuations in the form of sound waves or shock pulses. In contrast to conventional absorption spectroscopy (such as UV/Vis spectroscopy), PAS allows the determination of absorption coefficients over several orders of magnitude, even in opaque and strongly scattering samples. Small absorption coefficients, such as those encountered during trace gas monitoring, can be detected with cells with relatively short pathlengths. Furthermore, PA techniques allow absorption spectra of solid samples (including powders, chips or large objects) to be determined, and they permit depth profiling of layered systems. These features mean that PAS can be used for on-line monitoring in technical processes without the need for sample preparation and to perform depth-resolved characterization of industrial products. This article gives an overview on PA excitation and detection schemes employed in analytical chemistry, and reviews applications of PAS in process analytical technology and characterization of industrial products.

Acoustics↗
PubMed2005

A critical comparison of robotic versus conventional laparoscopic splenectomies.

The benefit of robotic systems for general surgery is a matter of debate. We compare our initial series of robotic splenectomies with our first series of conventional laparoscopic ones. A retrospective analysis of the first six robotic versus the first six conventional laparoscopic splenectomies is presented. Patients were matched with regard to age, body-mass index, ASA score, and preoperative platelet levels. All procedures were performed by a single surgeon. Size and weight of the resected specimens were comparable in both groups. Median overall operating time was 154 (range, 115-292) min for the robotic and 127 (range, 95-174) min for the laparoscopic group. No complications occurred. There were no open conversions. The median postoperative hospital stay was 7 (robotic group) and 6 (laparoscopic group) days. Median average costs were 6927 dollars for the robotic procedure versus $4084 for the conventional laparoscopic procedure (p < 0.05). Minimally invasive splenectomies are feasible using either conventional laparoscopic techniques or the da Vinci robotic system. In this analysis, procedures performed with the da Vinci robotic system resulted in prolonged overall operative time and significantly higher procedural costs. The use of a robotic system for laparoscopic splenectomy offers, at this stage, no relevant benefit and thus is not justified.

Adult↗
PubMed2005

Robotic-assisted thoracoscopic surgery (RATS) for benign and malignant esophageal tumors.

BACKGROUND: Robotic surgical systems are most effective for operations in areas that are small and difficult to reach. Ideal indications for this new technology have yet to be established. The esophagus possesses attributes that are interesting for general thoracic robotic surgeons. METHODS: Robotic-assisted thoracoscopic surgery (RATS) using the da Vinci system (Intuitive Surgical, Inc, Mountain View, CA) was performed in six patients with esophageal tumors. This comprised the dissection of the intrathoracic esophagus including lymph node dissection in four patients suffering from esophageal cancer and the extirpation of a benign lesion (one leiomyoma and one foregut cyst) in the remaining two patients. RESULTS: All procedures were completed successfully with the robot. The median overall operating time was 173 (160-190) minutes in the oncologic cases and 121 minutes in the benign cases, including the robotic act of 147 (135-160) minutes and 94 minutes, respectively. There were no intraoperative complications. One patient had to undergo a redo thoracoscopy because of a persistent lymph fistula. One cancer patient died after 12 months due to tumor progression and another patient had to be stented due to local tumor recurrence 19 months postoperatively. CONCLUSIONS: This first small series of various esophageal pathologies treated by robotic-assisted thoracoscopic surgery supports the impression that the esophagus is an ideal organ for a robotic approach. The potential of the da Vinci system, especially for oncologic indications, remains to be proven in future clinical trials.

Adenocarcinoma↗
PubMed2005

Laparoscopic splenectomy with the da Vinci robot.

BACKGROUND: We report our first series of minimally invasive splenectomies with a robotic surgical system. METHODS: From August 2001 to October 2003, laparoscopic splenectomies with the da Vinci operating robot were performed in 7 patients (five females and two males, ages 20 to 74 years). RESULTS: Indications for splenectomy were hematologic disorders in four patients and hypersplenism in three patients. Median dimensions of the resected spleens were 140 +/- 34 mm x 80 +/- 11 mm x 50 +/- 17 mm and median weight was 307 +/- 193 g. Median total operative time was 147 +/- 58 minutes including 107 +/- 49 minutes for the robotic act. There were no intraoperative complications and no conversions to open surgery. The median postoperative hospital stay was 7 days. CONCLUSION: This first series suggests that robotic splenectomy with the da Vinci surgical system is technically feasible and safe. It provides an alternative to the conventional laparoscopic procedure. Nevertheless, justification for this new technique will require a larger prospective series and longer follow-up.

Adult↗
PubMed2005

Robotic resection of an ectopic goiter in the mediastinum.

We report the first robotic resection of an ectopic mediastinal thyroid adenoma in a 72-year-old woman. This intervention was part of staged management for excessive bilateral cervical goiter with intrathoracic dispersion. The robotic resection was found to be feasible and safe. The robotic operating system offers better visual control and operative accuracy than does conventional thoracoscopy.

Adenoma↗
PubMed2005

Long-term follow-up after robotic cholecystectomy.

Most surgeons gain their first clinical experience with surgical robots when performing cholecystectomies. Although this procedure is rather easily applicable for the da Vinci surgical system, the long-term outcome after this operation has not yet been clarified. This study follows up our institutional first series of robotic cholecystectomies (June to November 2001). Patients were assessed on the basis of standardized management including a quality-of-life questionnaire, clinical examination, blood tests, and abdominal sonogram. The follow-up rate for 23 patients after robotic cholecystectomy was 100 per cent and the median follow-up time 33 (30-35) months. There was one (4%) recurrence of gallstone disease in a patient who suffered from solitary choledocholithiasis 29 months after robotic cholecystectomy. Abdominal sonogram, clinical examinations, and blood tests revealed no post-cholecystectomy-specific pathological findings. The main long-term symptoms were bloating (57%), heartburn (43%) and nausea (30%). Of the patients, 96 per cent (22 patients) felt that the operation had cured or significantly improved their specific preoperative symptoms. Long-term results after robotic laparoscopic cholecystectomy are excellent and comparable to those for the conventional laparoscopic procedure. The advanced vision control and instrument maneuverability of robotic surgery might open minimally invasive surgery also for complicated gallstone disease and bile duct surgery.

Adult↗
PubMed2004

Novel high-resolution temperature probe for radiofrequency dosimetry.

A novel integrated thermistor probe for temperature evaluations in radiofrequency-heated environments was realized. The probe's sensitive area is based on a highly resistive 50 microm x 100 microm layer of amorphous germanium processed on a glass tip. The small dimensions allow measurements with a distance as close as 150 microm from solid boundaries. Due to its high temperature resolution of 4 mK and its short response time of the order of 10 ms, the sensor is very well suited for dosimetric measurements in strong absorption gradients. The influence of radiofrequency (RF) electric fields on the signal is minimized due to the high resistance of the sensor and the leads. The probe was successfully used to determine the highly nonuniform absorption distribution resulting from the RF exposure of cell cultures placed in Petri dishes.

Body Burden↗
PubMed2004

Early experience with robot-assisted surgery for mediastinal masses.

BACKGROUND: We report the experience of a single institution with the minimally invasive resection of mediastinal masses using the da Vinci robotic surgical system. METHODS: From August 2001 to June 2003, 14 patients (5 men and 9 women aged from 21 to 77 years) with mediastinal masses were operated on minimally invasively with the da Vinci robotic system. This consisted of 9 thymectomies (6 thymomas, 2 nonatrophic thymic glands, 1 thymic cyst), 3 resections of paravertebral neurinomas, 1 ectopic mediastinal parathyroidectomy, and 1 resection of a lymphangioma. RESULTS: Complete, extended thymectomy was accomplished in all 9 cases, proven by examination of the thymic bed and resected specimen. In 1 patient with an hourglass-shaped neurinoma, conversion to an open procedure was necessary because the excessive size of the tumor limited vision. The median overall operation time was 166 minutes (range, 61 to 182) including 110 minutes (range, 46 to 142) for the robotic act. There were no intraoperative complications or surgical mortality. CONCLUSIONS: These preliminary results of our series suggest that application of the da Vinci robotic surgical system for resection of selected mediastinal masses is technically feasible and safe. It provides an alternative to open approaches and "conventional" thoracoscopy. Nevertheless, this new technique requires further investigation in larger series and longer follow-up.

Adult↗
PubMed2003

Congenital cystic lung disease: diagnostic and therapeutic considerations.

Congenital lung cysts such as congenital cystic adenomatoid malformation, pulmonary sequestration, congenital lobar emphysema, and bronchogenic cysts are rare but fascinating anomalies of lung development. While there are many similarities in terms of their presenting features, there are particular differences between the diagnostic groups that are important to highlight, especially in relationship to approaches to imaging and long-term outcome. A case of each entity is presented with an emphasis on the contemporary approach to diagnostic investigations and therapeutic options.

Adult↗
PubMed2003

Characterisation and predictive value of epidermal growth factor receptor status using quantitative real-time PCR combined with immunohistochemistry on non-small cell lung cancer specimens.

The frequency of increased EGFR-mRNA expression was determined in 57 patients suffering from NSCLC by applying quantitative real-time PCR. The findings were correlated with clinical parameters and the immunohistochemical (IHC) markers EGFR, c-erbB-2, c-erbB-3, Ki-67 and p53 on cryostat sections. Of the patients 46% showed increased EGFR-mRNA, 35% revealed an increased IHC-EGFR expression; 16% of the patients showed a combined positivity and 35% a combined negativity when applying both methods, and 17 (30%) of the cases revealed increased EGFR-mRNA without IHC-EGFR expression. This subgroup was characterised by p53 coexpression and the highest frequency of deaths (35% vs. 20%) indicating a more aggressive tumour type. In contrast to IHC - where positivity was seen predominantly in squamous cell carcinomas (48% vs. 27%) - EGFR-mRNA expression was observed equally in both histological subtypes (48% vs. 43%). PCR-EGFR and IHC-EGFR tumour typing identifies different tumour characteristics with different clinical courses. Whether this combined typing could help to identify patients who respond to anti-EGFR therapies is worth further testing.

Carcinoma, Non-Small-Cell Lung↗
PubMed2003

Automated real-time PCR to determine K-ras codon 12 mutations in non-small cell lung cancer: comparison with immunohistochemistry and clinico-pathological features.

A real-time PCR technique with automated computerized analysis (TaqMan ) was tested to detect K-ras mutations in 66 patients suffering from NSCLC. This technology is characterized by high reproducibility of data and a time-saving analysis procedure. In 11% (7/66) of the tumour specimens and 2% (1/58) of adjacent tumour-free lung specimens a K-ras codon 12 mutation was detected. In adenocarcinomas containing > or =40% tumour cells, however, K-ras mutations were seen in 25% of the cases. The point mutations detected in tumours were GGT right curved arrow TGT in five cases and GGT right curved arrow GTT in two cases. As compared with immunohistochemical parameters, the K-ras mutated group was characterized by a c-erbB-2 negativity (p=0.04) and a smaller number of c-erbB-3 (p=0.02) positive cases. EGFR, bcl-2, p53, Ki-67 and p120 expression did not differ significantly. Determination of the K-ras point mutations by automated TaqMan PCR in NSCLC tumour specimens is feasable and highly specific. Due to its high throughput capacity this method represents a valuable tool for routine screening.

Carcinoma, Non-Small-Cell Lung↗