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J Schubert

Publications and source records attributed to J Schubert.

At least 73 records · Page 4Linked to original sources
PubMed2001

Computerized contrast angiosonography: a new diagnostic tool for the urologist?

OBJECTIVES: To evaluate the diagnostic potential of echo-enhanced ultrasonography (US) for depicting the vascularization pattern of renal cell carcinoma (RCC), and calculating the first-pass effect using harmonic imaging, against that obtained by triphasic helical computed tomography (CT). PATIENTS AND METHODS: Sixty patients with surgically confirmed RCC underwent US using B-mode and power Doppler methods with or without an intravenous microbubble echo-enhancing agent. After depicting and defining the tumour extent by B-mode US, the first-pass effect/enhancement by the echo-enhancing agent within the lesion, and that of a reference area of unaffected renal cortex, were recorded on-line by calculating the mean pixel intensity. Time-intensity curves, i.e. the rise time and gradient of both the suspected tumour and reference areas, were constructed. RESULTS: Using B-mode US, the extent of all tumours was delineated (mean tumour size 3.8 cm, SD 0.6). After applying the microbubble agent all tumours were enhanced, whereas the perfusion was decreased (in 48%), increased (in 16%) or similar (in 36%) compared with the cortical reference area. Using the Hounsfield classification, these results correlated well with the hypo/hypervascularity shown on CT. CONCLUSION: Ultrasonography has considerable potential in diagnosing RCC, if combined with echo-enhancing methods, harmonic imaging and computer-based calculation of tumour vascularization. Dynamic US studies should provide a diagnostic yield similar to that of CT.

Carcinoma, Renal Cell↗
PubMed2001

[10 years experience with extracorporeal membrane oxygenation].

OBJECTIVE: Extracorporeal membrane oxygenation (ECMO) is a supportive therapy used for severe acute respiratory distress syndrome (ARDS). We present outcome, clinical parameters, and complications in a cohort of 245 ARDS patients of whom 62 were treated with ECMO. METHODS: Data of all ARDS patients were prospectively collected between 1991 and 1999. Outcome and clinical parameters of patients treated with and without ECMO were evaluated. RESULTS: Hundred-thirty-eight patients were referred from other hospitals, 107 were primarily located in our hospital. About one fourth of these patients was treated with ECMO. The survival rate was 55% in ECMO patients and 61% in non-ECMO patients. ECMO resulted in very few complications, one of them was fatal. No parameter before or during ECMO could be used to predict the individual prognosis. CONCLUSION: ECMO is a therapeutic option for patients with severe ARDS, likely to increase survival. However, a randomized controlled study proving its benefit is still awaited. Until the development of a causal or otherwise superior therapy ECMO should be used in selected patients.

Adult↗
PubMed2001

Volume-dependent compliance and ventilation-perfusion mismatch in surfactant-depleted isolated rabbit lungs.

OBJECTIVE: Volume-dependent alterations of lung compliance are usually studied over a very large volume range. However, the course of compliance within the comparably small tidal volume (intratidal compliance-volume curve) may also provide relevant information about the impact of mechanical ventilation on pulmonary gas exchange. Consequently, we determined the association of the distribution of ventilation and perfusion with the intratidal compliance-volume curve after modification of positive end-expiratory pressure (PEEP). DESIGN: Repeated measurements in randomized order. SETTING: An animal laboratory. SUBJECTS: Isolated perfused rabbit lungs (n = 14). INTERVENTIONS: Surfactant was removed by bronchoalveolar lavage. The lungs were ventilated thereafter with a constant tidal volume (10 mL/kg body weight). Five levels of PEEP (0-4 cm H2O) were applied in random order for 20 mins each. MEASUREMENTS AND MAIN RESULTS: The intratidal compliance-volume curve was determined with the slice method for each PEEP level. Concurrently, pulmonary gas exchange was assessed by the multiple inert gas elimination technique. At a PEEP of 0-1 cm H2O, the intratidal compliance-volume curve was formed a bow with downward concavity. At a PEEP of 2 cm H2O, concavity was minimal or compliance was almost constant, whereas higher PEEP levels (3-4 cm H2O) resulted in a decrease of compliance within tidal inflation. Pulmonary gas exchange did not differ between PEEP levels of of 0, 1, and 2 cm H2O. Pulmonary shunt was lowest and perfusion of alveoli with a normal ventilation-perfusion was highest at a PEEP of 3-4 cm H2O. Deadspace ventilation did not change significantly but tended to increase with PEEP. CONCLUSIONS: An increase of compliance at the very beginning of tidal inflation was associated with impaired pulmonary gas exchange, indicating insufficient alveolar recruitment by the PEEP level. Consequently, the lowest PEEP level preventing alveolar atelectasis could be detected by analyzing the course of compliance within tidal volume without the need for total lung inflation.

Animals↗
PubMed2001

A possible noninvasive method for the detection of bladder cancer in patients: microsatellite analysis of free DNA in urine and blood.

Six microsatellite markers were selected to detect shifts or loss of heterozygosity (LOH) in urine, serum, and plasma samples of 44 bladder cancer patients. After centrifugation at 15,000 g, we used supernatants for DNA analysis only. Tumor specimens were obtained by transurethral resection (TUR). Genetic alterations were detected in 33 of the 44 bladder tumors (75%). After polymerase chain reaction (PCR), DNA was detectable in 96% of all body fluid samples. Twenty-six percent of the detected microsatellite alterations of free DNA were tumor-specific, but 82% of all microsatellite changes of the tumors could be detected in body fluids. The study indicates that the simultaneous and multiple investigations of highly specific microsatellite markers could have a clinical relevance as a noninvasive tool for diagnosis and screening of bladder cancer. However, new ways for the sensitive DNA isolation of body fluids are needed.

Aged↗
PubMed2001

Familial and sporadic renal oncocytomas--a comparative molecular-genetic analysis.

OBJECTIVES: Genetic causes of sporadic and familial renal oncocytomas are not known. We analyzed these tumors genetically in order to detect tumor-specific chromosome alterations. METHODS: DNA from 26 sporadic and 31 familial renal oncocytomas were screened by comparative genomic hybridization according to standard protocols including degenerate oligonucleotide-primed PCR. RESULTS: Chromosome alterations were detected in 19/26 sporadic (73%) and in 4/31 familial renal oncocytomas (13%). Partial or complete losses of chromosome 1 were most frequently found in both sporadic (15/26) and familial tumors (2/4). Less frequently, loss of chromosome 14 (3/26) was detected in sporadic renal oncocytomas as well as losses of 2p, 2q, 4q, 10 and 18 and gains of 1q and 17q in individual sporadic tumors. Inter-tumor variation of chromosome aberrations was prominent in 1 patient, where 1 tumor showed gains of chromosomes 5, 6q, 7, 10p, 12 and 13q, whereas the second tumor exhibited gains of chromosomes 5 and 7 and loss of 10q. In contrast to sporadic renal oncocytomas, most familial tumors (87%) were devoid of chromosome instabilities. CONCLUSION: Our results demonstrate that partial or complete loss of chromosome 1 is the most common alteration in renal oncocytomas, sporadic and familial. However, chromosome changes are much rarer in familial than in sporadic renal oncocytomas.

Adenoma, Oxyphilic↗
PubMed2001

Renal cell carcinoma in renal graft recipients and donors: incidence and consequence.

INTRODUCTION AND OBJECTIVES: Numerous studies have reported an increasing incidence of small renal cell carcinoma (RCC). De novo RCC in a renal allograft is a rare event and has special implications in renal transplant recipients. The objective of this study was to retrospectively evaluate the incidence of RCC in renal graft recipients and donors and to determine a procedure in cases with newly detected small renal tumors at the time of kidney preparation before transplantation. MATERIAL AND METHODS: We mailed a questionnaire to 38 German transplant clinics and received answers from 27 centers. A total of 10,997 renal graft recipients were included in the period of 1990-1998. RESULTS: In 30 kidneys (0.273%) RCC was detected at the time of preparation before transplantation. There were 23 male and 3 female donors. No bilateral RCC was described. The mean age of the donors with RCC was 50.9 years (range 37-72 years). The tumors had a mean size of 2.2 cm (range 0.4-6 cm). 67% of the patients had a renal tumor smaller than 20 mm. In 26/27 centers the decision to transplant relies on the result of the immediate section for microscopic examination. 16 patients (0.145%) developed RCC 3-12 years after renal transplantation (mean 7.4 years). The mean tumor size was 2.5 cm (range 2-2.8 cm). In 50% a grade 1 and in the other 50% a grade 2 carcinoma was found. CONCLUSIONS: Because of the RCC incidence in donor candidates we recommend an ultrasound screening of the native kidneys before renal explantation and an immediate preparation of the kidney surface especially in donors older than 45 years. In cases with small renal lesions we recommend an immediate section for microscopic examination before transplantation to prevent tumor implantation into an otherwise healthy patient. The frequency of RCCs after renal transplantation necessitates careful clinical and instrumental examinations in organ-transplanted recipients both before and at regular intervals after transplantation, including the patient's kidneys.

Adult↗
PubMed2001

Endocrine alteration in the adrenal gland in kidney transplant patients.

INTRODUCTION: Endocrine alterations associated with chronic renal failure have been reviewed recently. Some of these alterations are of clinical relevance. The aim of this study was to investigate the effect of renal transplantation on the endocrine system of the adrenal gland of the transplant recipients. METHODS: The serum angiotensin-converting enzyme (SACE), plasma renin (PR) and plasma aldosterone (PA) were examined in 30 patients before and after renal allotransplantation. Additionally measured parameters were blood pressure, serum creatinine, potassium, sodium, the duration of dialysis and immunosuppressive medication. RESULTS: Six weeks after renal transplantation, serum creatinine decreased from 820.07 +/- 172.01 to 138.12 +/- 67.54 micromol/l. In the same period, serum potassium decreased from 5.42 +/- 0.89 to 4.17 +/- 0.42 mmol/l. PA and PR decreased from 1,150.84 +/- 976.06 to 233.52 +/- 217.07 micromol/l, and from 121.07 +/- 100.12 to 26.16 +/- 10.86 microU/ml, respectively. SACE decreased from 0.21 +/- 0.21 to 0.13 +/- 0.11 micromol/l. No significant correlation was seen with blood pressure, serum sodium, the duration of dialysis and immunosuppressive drugs. Additionally, 2 patients with acute renal graft dysfunction showed significant increases in PR and PA. After successful treatment both levels declined very quickly to prerejection levels. Patients after binephrectomy show no elevation in PR (5-47 microU/ml) or PA (21-416 micromol/l) neither before nor after renal transplantation. CONCLUSIONS: We conclude that renal transplantation has profound effects on the recipient's renin-angiotensin-aldosterone system. Because of the rapid depression after renal transplantation, it does not appear to be involved in the pathogenesis of post transplantation hypertension but may reflect a role for repair processes after renal allotransplantation.

Adrenal Gland Diseases↗
PubMed2001

Interferon-alpha suppresses the antiapoptotic effect of NF-kB and sensitizes renal cell carcinoma cells in vitro to chemotherapeutic drugs.

BACKGROUND: Immunochemotherapy (ICT) with interleukin-2 (IL-2) and interferon-alpha (IFNalpha) with a secondary effector (5-fluorouracil, 5 FU) is the only promising treatment for advanced renal cell carcinoma (RCC). With IFNalpha, besides the activation mechanisms of the immunosystem, a direct antitumor effect on tumor cells is expected. MATERIALS AND METHODS: NF-kB activity in three permanent cell lines (Hep2, HepG2, HT29) and in primary RCC cell lines was measured after incubation with tumor necrosis factor-alpha (TNFalpha), IFNalpha, IFN-gamma, TNFalpha+IFNalpha, and IFNgamma+TNFalpha, respectively. NF-kB activity and induction of apoptosis by chemotherapeutic drugs (5FU and doxorubicin) were determined in cells transfected with a constitutively active NF-kB p65 or a dominant negative IkB. RESULTS: NF-kB signaling induced by TNFalpha is suppressed by IFNalpha and IFNgamma in the permanent cell lines and in the primary RCC tumor cell cultures. In an in vitro ICT model we show that pretreatment of RCC with IL-2 and IFNalpha leads to a diminished NF-kB response to TNFalpha. In certain tumors, this correlates with increased susceptibility to investigated chemotherapeutic drugs as shown by annexin stain and cell elimination. Modulation of the cellular NF-kB state by a constitutively active p65 or a dominant negative IkB mimics this effect. The IkB construct leads to the same effects as IL-2/IFNalpha pretreatment as shown by predominant elimination of the transfected cells from the overall population, while introduction of p65 leads to a partial rescue from the effect of IL-2 and IFNalpha. The described effect, however, applies only to a selection of primary cell cultures. CONCLUSIONS: Besides the immunomodulation effects, treatment of RCC with IL-2/IFNalpha leads to a proapoptotic state in certain tumors. The relevant mediator seems to be IFNalpha by suppression of the antiapoptotic effect of NF-kB. These data can provide an experimental base for correlation with real patient outcome after ICT.

Antineoplastic Agents↗
PubMed2001

Differential expression of cytokines and cytokine receptors in renal cell carcinoma.

Modulation of immunomechanisms by tumor cells can be caused by secretion of cytokines. In vitro data are usually gained in culture systems. It is debatable whether these systems are representative of the conditions inside the respective tumor tissues. Immunohistochemical studies of tumor tissue cryostats were compared with those in matched primary renal cell carcinoma tumor cell cultures. Results were correlated with histopathological characteristics and the in vitro cytotoxic effect of autologous tumor infiltrating lymphocytes (TILs). Expression of all studied cytokines and cytokine receptors could be shown in cryostats and cell cultures, but the detection pattern varied individually. The immunohistochemical results in cryostats were in good accordance with those in cell cultures. Expression of TGFbeta1 both in cryostats and cell cultures significantly correlated with the lack of cytotoxic activity of autologous TILs. Representative data can be obtained in tumor culture systems of primary renal cell carcinoma. TGFbeta1 secretion could play an important role in the interactions between tumor and cytotoxic cells.

Carcinoma, Renal Cell↗
PubMed2001

Finite element analysis of a tandem screw configuration in sagittal split osteotomy using biodegradable osteosynthesis screws.

The goal of the present study was to determine the mechanical stability of selected osteosynthesis screws in a paired linear configuration in cases of bilateral sagittal split osteotomy of the mandible. A mandible model was created that consisted of 22,846 elements and 4,879 nodes. The following screws were tested in the tandem screw configuration: the poly-L-lactic acid (PLLA) in accordance with Harada and Enomoto, the Isosorb screw (Aesculap, Germany), the BioSorbFX screw (Bionix Implants, Finland), and the Lactosorb screw (WL. Lorenz, USA). The mechanical parameters of the materials studied were adopted from the literature or were based on manufacturer information. With the precondition that the materials each be stressed to the ultimate tensile strength, the following chewing forces could be neutralized: 100 N by 2.0-mm titanium mini-screws, 117.5 N by PLLA screws in accordance with Harada and Enomoto, 90.0 N by Isosorb screws, 89.0 N by BioSorbFX screws, and 35.0 N by Lactosorb screws. Here the peri-implant bone was stressed within limiting values with the titanium miniscrew, and the PLLA screw according to Harada and Enomoto, but not the osteosynthesis material itself. The finite element method (FEM) appears suitable for simulating complex mechanical stress situations in the maxillofacial area. As a result, significant time and materials (animal tests) can be saved when developing new or modified materials

Absorbable Implants↗
PubMed2000

Central nervous system neurons labeled following the injection of pseudorabies virus into the rat prostate gland.

BACKGROUND: The human prostate gland plays an important role in male fertility and is involved in different functional pathologies of the male lower urinary tract (LUT). The role of the prostate in these medical disorders is mainly unknown. Traditional surgical therapeutic attempts often fail to help these patients. For years, the clinical sciences have been stagnating due to a lack of basic science knowledge. Investigations into neuroanatomy and neurophysiology are urgently needed. Therefore, the neuroanatomy of the prostate gland in an experimental setup was explored. Recent progress in neuroscience methodology allows a transneuronal tracing by using a self-amplifying virus tracer, pseudorabies virus (PRV). METHODS: Sixty-two individual adult male Sprague-Dawley rats were used for retrograde transneuronal mapping of the spinal cord and brain stem after PRV-injection and control experiments. A PRV-tracer (5 microl, 1 x 10(8) pfu/ml) was injected into the prostate gland. After a survival time of 72, 96, or 120 hr, the animals were sacrificed. Brain and spinal cord were harvested via a dorsal laminectomy. After cutting on a freezing microtome, the tissue was immunostained for PRV. RESULTS: PRV-positive cells were found within the sacral (S1-S2) and the thoracolumbar (T13-L2) spinal cord. At the supraspinal level, positive cells were found within the following regions: nucleus raphe, lateral reticular formation, nucleus gigantocellularis, A5 noradrenergic cell region, locus coeruleus, pontine micturition center, hypothalamus, medial preoptic region, and periaquaductal gray. CONCLUSIONS: This is the first investigation on the central innervation of the prostate gland showing a broad central representation of neurons involved in the control of the prostate gland. It is obvious, comparing data from the literature, that there is a broad overlap in the innervation of pelvic visceral organs (bladder, rectum, and urethra). The appreciation of these neuroanatomical circumstances allows a growing understanding of common urological pathologies within the pelvis (pelvic pain, lower urinary tract, and bowel dysfunction).

Animals↗
PubMed2000

[Basaliomas].

Basal cell carcinoma is the most frequent skin tumor in humans. It is mostly located in the face and its incidence is steadily rising. The tumor develops from basal, undifferentiated epithelial cells of the skin and its appendices and shows locally destroying growth, but generally without metastatic outspread typical of carcinomas of other origin. The tumor does not occur on the vermilion border of the lips and in the mucosa. Surgery is the most widespread and accepted treatment of basaliomas. It gives the possibility of histologic diagnosis of the whole specimen including margins of resection and allows immediate closure of the defect by means of plastic surgical methods. Regarding aesthetic and functional demands of the region, maxillofacial surgeons have the best prerequisites for this treatment. Recent research results clearly demonstrate the role of UVB light in the etiology, which is modified or promoted by genetic factors. Because of its typical malignant properties, such as progressive growth and infiltration, the term "basalioma", which is mostly used in German, should be replaced by "basal cell carcinoma" as it is known in the international literature.

Basal Cell Carcinoma↗
PubMed2000

Ex vivo stimulation of renal tubular p-aminohippurate transport by dexamethasone and triiodothyronine in human renal cell carcinoma.

This paper is the third of a long-term planned series of papers dealing with ex vivo investigations of drug transport in human kidney. The aims of this study are (a) to investigate whether or not human renal cell carcinoma (RCC) can actively accumulate p-aminohippurate (PAH) and (b) to test the response of RCC on dexamethasone or triiodothyronine (T3) using tissue slices ex vivo. By this approach, the accumulation capacity of RCC should be stimulated as a prerequisite for an increased uptake of anti-tumour drugs. Tissue slices of RCC samples of 30 patients were incubated for 24 h in Williams medium E containing 0.01-50 microM dexamethasone or T3. Thereafter, slices were placed in PAH-containing Cross-Taggart medium, and PAH uptake into kidney tissue was measured for 2h under standardised conditions as described previously. In intact human renal cortical slices, PAH uptake capacity, expressed as slice to medium ratio (QS/M), was about 2.8 +/- 0.16 after 24 h of incubation and increased significantly in dexamethasone-containing medium in a concentration-dependent manner, up to approximately 150%, whereas T3 did not influence PAH accumulation. On the other hand, in RCC the PAH accumulation capacity was completely abolished (QsM approximately 1). However, after administration of dexamethasone, the accumulated amount of PAH increased significantly in RCC tissue in a concentration-dependent manner, up to approximately 190%. T3 was without effect in RCC, too. Surprisingly, the dexamethasone-mediated stimulation could be differentiated into responders and non-responders, with maximal effects at different concentrations for each patient. Nevertheless, the maximal transport rates remained low in RCC, even under hormone influence. In conclusion, a moderate stimulation of tubular transport capacity can be shown ex vivo in human RCC. This phenomenon is only of a relatively low degree compared with intact renal tissue. However, in principle, the response of RCC on dexamethasone could form a basis for further therapeutic strategies to overcome multi-drug resistance in RCC patients. For this purpose, additional experiments analysing the expression of transporters of the ABC cassette-type are in progress.

ATP-Binding Cassette Transporters↗
PubMed2000

Imaging in ureteral complications of renal transplantation: value of static fluid MR urography.

Ureteral obstruction is an infrequent complication after renal transplantation that may cause rapid loss of transplant function. We tested static fluid MR urography for determining the cause of graft hydronephrosis. Magnetic resonance urography was performed in nine transplants with dilated collecting systems on ultrasound. A heavily T2-weighted 3D turbo spin-echo sequence on a 1.5-T scanner was used and maximum intensity projections were obtained. The patients also underwent excretory urography (n = 1), renal scintigraphy (n = 1), antegrade pyelography (n = 3), voiding cystourethrography (n = 4), and non-enhanced CT (n = 2). Six patients had pathologic conditions including ureteral stricture, compression by lymphoceles, implantation stenosis, vesicoureteral reflux, and late-occurring transitional cell carcinoma at the implantation site. Static MRU was able to diagnose or exclude a dilation of the graft collecting system. It visualized the course of the ureters and localized the obstruction site in four of five obstructed transplants. In one case the ureter was obscured by lymphoceles, which were demonstrated by hydrographic MRU as well. The definite cause for obstruction was provided in only 2 of 5 cases. Dilation due to vesicoureteral reflux could not be differentiated. The current multimodality approach to renal transplant imaging already provides comprehensive assessment of graft hydronephrosis. Static MRU may be useful in some cases since complications associated with intravenous iodinated contrast or antegrade pyelography can be avoided. Its main drawback, the lack of functional information, may be overcome by combining it with contrast-enhanced MRU.

Adult↗
PubMed2000

[The preparation of retrocavities in apicoectomies].

The purpose of this in vitro and in vivo study was to compare the quality of retrograde cavities and retrofilling using various retrograde techniques (microhead, ultrasonic). The quality was evaluated on the basis of dye penetration, macroscopic control, and both light microscopic and scanning electron microscopic examination. A total of 40 extracted teeth with a single canal were analyzed. The clinical result was evaluated in 25 patients with root-filled teeth and the indication of apicoectomy. Statistical analysis indicated that the seal was significantly better with ultrasonically prepared cavities than with microhead preparation. Retrofillings prepared ultrasonically also showed significantly fewer peripheral fissures. The scanning electron microscopic examination, however, demonstrated peripheral fissures in all filled teeth. Furthermore, the cavities prepared ultrasonically had a smoother surface and a lower smear layer. This preparation produced a more pleasing final result. The advantages of better accessibility during the preparation, namely, more precise preparation of the retrofilling and only minor substance loss were confirmed clinically. Using the ultrasonic equipment, absolutely sterile working conditions are present.

Apicoectomy↗
PubMed2000

[Pathogen spectrum and resistance status of exclusively anaerobic odontogenic infections].

Out of 440 dentogenic pyogenic infections, 171 exclusively caused by anaerobes were investigated to understand the importance of anaerobic bacteria in dental pyogenic processes better. Grampositive anaerobic bacteria dominated. The predominant grampositive isolates in monoinfections were Peptostreptococci and in the case of mixed infections, strains of the genus Eubacterium. Strains of Prevotella and Porphyromonas dominated the gramnegative anaerobic spectra. The resistance to penicillin was very low. Altogether, only one strain of Prevotella oris and one strain of Prevotella oralis showed resistance to penicillin.

Bacteria, Anaerobic↗