Search PubMed⌕ Search

Biomedical subjects

T Vogl

Publications and source records attributed to T Vogl.

At least 55 records · Page 3Linked to original sources
PubMed1999

Tumor diagnosis in the adult liver transplant candidate.

Hepatic transplantation has emerged as a potentially curative treatment of certain malignant hepatic neoplasms such as hepatocellular carcinoma, bile duct carcinoma, fibrolamellar hepatocellular carcinoma, metastases from neuroendocrine tumors, and epithelioid hemangioendothelioma. In the early years of hepatic transplantation, there was great enthusiasm to cure patients with unresectable hepatobiliary malignancy. This early enthusiasm was tempered by the unfavorable outcome of transplantation in advanced cases of malignancy and the organ-donor shortage. Presently, patients have to be selected with predictable likelihood for long-term survival. Pre-transplantation imaging is indispensable for detection, characterization, staging, and surgical road-mapping before the procedure. The present article focuses on the role of imaging modalities in these different aspects of preoperative assessment.

Adult↗
PubMed1999

Calcium-induced noncovalently linked tetramers of MRP8 and MRP14 detected by ultraviolet matrix-assisted laser desorption/ionization mass spectrometry.

MRP8 and MRP14 are members of the S100 family of calcium-binding proteins which play an important role during calcium-induced activation of phagocytes. Both proteins form noncovalently associated complexes as a prerequisite for biological functions. The exact stoichiometric composition of these complexes, however, has not been completely clarified yet. In the present study we show for the first time by ultraviolet matrix-assisted laser desorption/ionization mass spectrometry (UV-MALDI-MS) the calcium-induced formation of noncovalently associated (MRP8/MRP14)2 tetramers. Furthermore, we could determine posttranslational modifications of MRP8 and MRP14, the stoichiometric proportion of the two known MRP14 isoforms in the complexes as well as the number of calcium ions bound to the single MRP8 and MRP14 monomers and tetramers. MRP14 showed a higher affinity for calcium than MRP8. Upon complex formation the calcium binding increased to maximal saturation of the known EF hands in the complexed forms. Calcium-induced stabilization of the MRP8/MRP14 complexes was confirmed by DSC studies. Our results extend scope and application of UV-MALDI-MS by allowing identification of noncovalent protein complexes, the identification of minor alterations of subunits in such complexes as well as the determination of bound calcium ions.

Antigens, Differentiation↗
PubMed1999

Free hapten molecules are dispersed by way of the bloodstream during contact sensitization to fluorescein isothiocyanate.

The fate of the contact sensitizer fluorescein isothiocyanate was traced by means of fluorescence spectrophotometry and flow cytometry. The hapten applied to one ear rapidly entered the circulation by way of local lymphatics and blood vessels. It was dispersed for several hours essentially as free hapten, released from a reservoir left behind at the site. Hapten molecules coupled to plasma proteins while circulating and reacted with white blood cells. Total cells of regional lymph nodes, spleen, and distant lymph nodes became fluorescent in successive order. Fluorescence of CD11c-positive dendritic cells exceeded significantly that of lymphoid cells. Total spleen cells and total nonregional lymph node cells were shown in vitro to drive committed lymph node cells to proliferation. The mechanism disclosed is proposed to counterbalance the action of epidermal Langerhans cells for regulation of contact hypersensitivity.

Animals↗
PubMed1999

Radiation exposure in spiral computed tomography. Dose distribution and dose reduction.

RATIONALE AND OBJECTIVES: The authors investigate the dose distribution of spiral and conventional computed tomography (CT) with film densitometry and to present a new method of evaluating the possibility of dose savings with spiral CT. METHODS: Films were exposed in a cuboid polymethyl-methacrylate phantom in conventional and spiral scan technique. Axial density profiles were obtained by digitizing the films using a fluorescent light scanner. The ratio of the number of rotations in spiral CT to the number of slices in conventional CT was calculated. RESULTS: In spiral CT with a pitch of 2, the densities in all points were lower than those in corresponding points in spiral CT with a pitch of 1 and in conventional CT with slice distance equal to slice thickness. A pitch of 1.5 in spiral CT led to a dose reduction of 14% to 30% compared with conventional CT. CONCLUSIONS: Increasing the pitch in spiral CT leads to a reduction of both integral dose and absorbed doses within the examined body region. The reduction of the integral dose can be significant, especially in cases where slice overlapping is diagnostically advantageous.

Humans↗
PubMed1999

Contact tolerance.

Contact tolerance describes an immunological state which is caused by ordinary contact allergens painted in doses too low to sensitize, either once or repeatedly, onto healthy intact skin. The tolerance state accomplished by this means in BALB/c and C57BI/6 mice was found to be mediated by hapten-specific T cells that adoptively transferred tolerance to naive recipients. Furthermore, these cells were shown to be sensitive to cyclophosphamide, to express the Lyt2+ (CD8) phenotype, and to produce, upon restimulation in vitro, predominantly anti-inflammatory cytokines such as IL-4, IL-5 and IL-10. These data indicate that contact tolerance of the low zone type is actively mediated by Th2-like CD8 T cells rather than arising as a consequence of clonal anergy. The induction of contact tolerance appeared to be strictly dose-dependent. As opposed to sensitizing doses of allergen, subsensitizing doses did not involve epidermal Langerhans cells discernibly. This was suggested by their normal ultrastructure, their unaffected adenosine triphosphatase system, the inefficacy of functional blocking and excision experiments. Both radiolabeled and fluorescent contact sensitizers were observed to readily enter the bloodstream, thereby being dispersed throughout the body. Presumably, contact tolerance is induced systemically rather than locally. The presence of hapten-specific tolerance can only be uncovered through a subsequent attempt to sensitize. If the attained sensitization turns out to be significantly lower than that of immunologically naive controls, and if sensitization to chemically unrelated sensitizers is not impaired, hapten-specific tolerance does exist. Thus, contact tolerance is a result obtained from experimental sensitization in animals. Nonetheless, it is assumed to occur also in humans, although it is not demonstrable unless different proofs of existence become available.

Administration, Topical↗
PubMed1998

Imaging in epidural lipomatosis.

This paper reviews the literature concerning symptomatic epidural lipomatosis. The different diagnostic procedures (conventional myelography, computed tomography, and magnetic resonance imaging) and therapeutic approaches (including medical treatment, surgery, and dietary influence) are discussed.

Journal Article↗
PubMed1998

Copurification of P6, MRP8, and MRP14 from human granulocytes and separation of individual proteins.

A method is described for purification of P6, MRP8, and MRP14, three calcium-binding proteins assigned to the S100 protein family. The purification procedure included preparation of human granulocytes, ammonium sulfate precipitation, and anion-exchange chromatography and resulted in the copurification of P6, MRP8, and MRP14. Individual proteins were separated by either preparative isoelectric focusing or preparative SDS-PAGE. The procedure was carried out in the course of 4 days and yielded several milligrams of essentially pure P6, MRP8, and MRP14 in either native or denatured form.

Amino Acid Sequence↗
PubMed1998

[Dose distribution in conventional CT and spiral CT and on the topic of dose reduction with spiral CT].

OBJECTIVE: To compare spiral CT with conventional CT with regard to the dose distribution in the irradiated body and to examine when an increase in the table feed in spiral CT leads to a dose reduction compared with conventional CT. METHODS: In order to show the dose distribution, films were exposed in an acrylic phantom. The nominal slice thickness was 5 mm; the slice distance in conventional CT was 5 and 10 mm; the table feed in spiral CT was 5 and 10 mm per rotation (pitch 1 and 2). The integral doses delivered in spiral CT and conventional CT were related to the table feed per rotation or slice distance, respectively, and were compared arithmetically with each other. RESULTS: Spiral CT showed reduced dose fluctuations in axial direction compared with conventional CT. Only in conventional CT with a slice distance of 5 mm did the axial dose distribution show relative dose peaks near the rotation axis. The longer the body region to be examined is, the less table feed is necessary in spiral CT for a dose reduction. From a length of 15 times the slice thickness, a pitch of > 1.1 leads to a reduction of the integral dose compared with conventional CT. CONCLUSIONS: The continuous table feed in spiral CT results in evenly distributed axial dose distributions compared with the discontinuous scanning in conventional CT. The spiral technique can give an important contribution to dose reduction in CT.

Equipment Design↗
PubMed1998

Recurrence-free survival after liver transplantation for small hepatocellular carcinoma.

Recurrence-free survival (RFS) in patients with small hepatocellular carcinoma (HCC) after orthotopic liver transplantation (OLT) was analyzed. From 1988 until 1996, 725 OLTs were performed in 669 patients. In 52 adults, HCC was confirmed histologically. OLT was limited to patients with small (< 5 cm) HCC with a maximum number of three nodules. Actuarial survival for these 52 patients at 1 and 5 years is 88% and 71%. RFS was defined as time until death without recurrence time until follow up with a diagnosis of recurrence, or, in patients without recurrence, time of last follow up. Overall, the 5-year RFS was 60%. Five-year RFS was less for bilobar compared to unilobar tumors (36% vs 70%), less for stage IVa tumors (UICC) compared to stage I-III tumors (17% vs 71%), and less for multiple compared to solitary tumors (54% vs 67%). In conclusion, potential cure may be achieved in more than 50% of all transplanted patients.

Actuarial Analysis↗
PubMed1998

Anterior cruciate ligament reconstruction: the diagnostic value of MRI.

A prospective study was carried out in order to evaluate the predictive value of MRI in the early postoperative course after cruciate ligament replacement. Twenty patients who had undergone anterior cruciate ligament reconstruction using autologous patellar tendon/bone grafts were examined clinically and with contrast enhanced MRI at 2, 12 and 24 weeks, and 1 and 2 years after operation. The clinical findings were evaluated according to the scores established by Lysholm, OAK and IKDC. The MRI scans (SP 63, 1.5 Tesla) were assessed in terms of the quality and signal intensity of the reconstructed ligaments. During the first postoperative year there was a significant increase of signal intensity and in homogeneity of the neoligament on in the MRI. Seventeen patients had an average value for signal/noise of 1.1 at two weeks after surgery, which had increased to 7.1 at 1 year. In 14 patients the reconstructed ligament could not be evaluated in MRI scans after 1 year but clinical instability was not suspected in any of these patients. Two years after operation the MRI signal, intensity of the neoligament was again decreasing.

Adolescent↗
PubMed1998

[Color-coded signal-enhanced duplex ultrasonography of space-occupying intramammary processes].

PURPOSE: Prospective comparison of plain and signal-enhanced frequency and amplitude-modulated colour Doppler ultrasound of intramammary tumours to evaluate new criteria for diagnostic analysis. METHODS: Frequency and amplitude-modulated colour Doppler examination with qualitative and quantitative analysis of 80 potentially malignant intramammary lesions were performed before and after application of d-galactose. RESULTS: Signal-enhanced sonography revealed a typical vessel morphology of primary and recurrent breast cancer facilitating differential diagnosis. In 18 (frequency modulated US) or 16 (amplitude modulated US) of 51 carcinomas, the typical malignant vascularisation structure was sufficiently visible only after application of the signal enhancing agent. In 50% of the fibroadenomas, Doppler analysis of the vessels was possible only after application of d-galactose. CONCLUSION: The application of d-galactose provides additional criteria for the differential diagnosis of breast lesions due to improved visualisation of the vascularisation structure.

Adult↗
PubMed1998

[Signal-enhanced color-coded duplex sonography of reactively and metastatically enlarged lymph nodes].

PURPOSE: Prospective comparison of B-mode-, plain and signal-enhanced colour Doppler ultrasound to evaluate new criteria for assessment of the tumour status of enlarged cervical lymph nodes. METHODS: Colour Doppler sonography was performed before and after application of d-galactose in 35 patients with suspected lymph node metastases of the neck. Sonomorphology was analysed qualitatively, maximal flow rate, pulsatility index and resistance index were determined quantitatively. RESULTS: Signal enhanced Doppler revealed a typical vessel morphology of the lymph nodes facilitating differential diagnosis. In 23%, vascularisation of the lymph nodes was only visible after application of the signal-enhancing agent (benign: 44%, malignant: 5%). The measurement of flow velocity and the calculation of RI and PI did not lead to a reliable differentiation between malignant and benign lymph nodes whereas B-mode sonography yielded highly valid results. CONCLUSION: The application of d-galactose facilitates differentiation between malignant and benign lymph nodes.

Aged↗
PubMed1998

Preoperative hyperthermia combined with radiochemotherapy in locally advanced rectal cancer: a phase II clinical trial.

OBJECTIVE: A prospective phase II study was performed to determine the feasibility and efficacy in terms of response rate, resectability, and morbidity in patients with locally advanced rectal cancer who received preoperative regional hyperthermia combined with radiochemotherapy (HRCT). SUMMARY BACKGROUND DATA: Recent studies suggest that preoperative radiochemotherapy in locally advanced rectal cancer can induce downstaging, but after resection the incidence of local recurrences remains high. Hyperthermia (HT) may add tumoricidal effects and improve the efficacy of radiochemotherapy in a trimodal approach. PATIENTS AND METHODS: Thirty-seven patients with histologically proven rectal cancer and T3 or T4 lesions, as determined by endorectal ultrasound and computed tomography, entered the trial. 5-Fluorouracil (300-350 mg/m2) and leucovorin (50 mg) were administered on days 1 to 5 and 22 to 26. Regional HT using the SIGMA 60 applicator (BSD-2000) was given once a week before radiotherapy (45 Gy with 1.8-Gy fractions for 5 weeks). Surgery followed 4 to 6 weeks after completion of HRCT. RESULTS: Preoperative treatment was generally well tolerated, with 16% of patients developing grade III toxicity. No grade IV complications were observed. The overall resectability rate was 32 of 36 patients (89%), and 31 resection specimens had negative margins (R0). One patient refused surgery. In 5 patients (14%), the histopathologic report confirmed no evidence of residual tumor (pCR). A partial remission (PR) was observed in 17 patients (46%). The survival rate after 38 months was 86%. In none of the patients was local recurrence detected after R0(L), but five patients developed distant metastases. CONCLUSION: Preoperative HRCT is feasible and effective and may contribute to locoregional tumor control of advanced rectal cancer, which is to be proven in an ongoing phase III trial.

Adenocarcinoma↗
PubMed1998

[Etiologic factors and incidence of ischemic type biliary lesions (ITBL) after liver transplantation].

Ischemic type biliary lesions (ITBL) are defined as non-ischemic and non-immunological destruction of the graft's biliary tree after liver transplantation. In a retrospective analysis we investigated possible etiological factors and the incidence of ITBL. Differing from previous studies, the incidence of ITBL was low (2.6%) and we did not observe a significant effect of cold ischemic time or initial peak transaminases, as indicator of the reperfusion injury. However, we detected a significant decrease in the incidence of ITBL in self-retrieved organs and in organs preserved with arterial pressure perfusion.

Adolescent↗
PubMed1997

Thermodynamic stability of annexin V E17G: equilibrium parameters from an irreversible unfolding reaction.

Conformational stability of the membrane-binding protein annexin V E17G has been determined by high-sensitivity differential scanning microcalorimetry (DSC) measurements and by isothermal, guanidinium hydrochloride (GdnHCl)-induced unfolding studies. Wild-type annexin V and the E17G mutant protein studied here are structurally almost identical. Therefore, it can be expected that the present results will not deviate significantly from the stability data of the wild-type molecule. Thermal unfolding is irreversible, while GdnHCl unfolding shows a high degree of reversibility. We were able to demonstrate that characteristic features of annexin V E17G unfolding permit us to extract from the kinetically controlled heat capacity curves thermodynamic equilibrium parameters at the high heating rates. The thermodynamic quantities obtained from the DSC studies in phosphate buffer at pH 7.0 are as follows: t1/2 = 54.7 degrees C (heating rate of 2.34 K min-1), delta H0 = 690 kJ mol-1, and delta Cp = 10.3 kJ mol-1 K-1 which correspondends to a value of delta G0D (20 degrees C) of 53.4 kJ mol-1. When compared on a per gram basis, these thermodynamic parameters classify annexin V E17G as a marginally stable protein. This conclusion is consistent with structural and functional features of the protein that require conformational adaptability for hinge-bending motions and pore formation on interaction with membranes. We observed a large difference between the change in the Gibbs energy value derived from the heat capacity studies and that determined from the GdnHCl unfolding curve. The difference appears to stem from a specific interaction of the protein with the denaturant that results in both a low half-denaturation concentration C1/2 of 1.74 M and a small slope (6.0 kJ L mol-2) of the delta Gapp versus [GdnHCl] plot. The extraordinary interaction of annexin V with GdnHCl is also manifested in the enormous depression of the transition temperature delta t1/2 (= 18 degrees C) when the GdnHCl concentration is increased from 0 to 1 M. "Regular" proteins experience an average decrease in the transition temperature of 8 +/- 2 degrees C per 1 M change in the concentration of GdnHCl.

Annexin A5↗
PubMed1997

[Thermometry by measuring the chemical shift of lanthanide complex].

BACKGROUND: In the long-term, non-invasive thermometry is vital for the continued clinical and technological development of regional hyperthermia. In magnetic resonance tomography. T1 relaxation time, diffusion and proton resonance frequency are used to measure temperature distributions. When used clinically in the pelvic region, all of these methods are plagued with errors and artefacts on account of the tissue relationships, tissue changes under hyperthermia, physiological and stochastic movements, inhomogeneities, drift phenomena and instabilities. MATERIAL AND METHOD: We tested the relationship between the temperature and the chemical shift of a methyl group of a lanthanide complex with central atom praseodymium (Pr-MOE-DO3A. Schering AG). To do this we used cylindrical phantoms containing a 5-mmol-solution of this temperature-sensitive substance. High resolution spectra and relaxation times were determined in a Bruker AMX at 11.5 T. A calibration curve was then recorded by a Siemens Magnetom SP63 at 1.5 T. Local temperature distributions were determined using the chemical shift imaging method, with a matrix size of 16 x 8 and a narrow-band excitation pulse. The temperature distribution was created using a Nd:YAG laser applicator. RESULTS: At a distance of -25.7 ppm from the water line, we found a singlet line with a temperature-dependent chemical shift of 0.13 ppm/C. In the phantom experiment we found that the chemical shift had a linear relationship with a gradient independent of the surroundings, and a temperature resolution of +/-0.6 degree C. With a concentration of 1 mmol/l, a matrix size of 8 x 8 and a measurement period of 5 s per acquisition, phantom measurements using the CSI method produced a signal to noise ratio of 3.5 per acquisition, i.e a measurement period of 10 to 20 s per spectrum. CONCLUSIONS: Our in vitro data show that spectroscopic temperature measurement using a temperature-sensitive praseodymium complex with a therapeutically practical concentration of 1 mmol/l already appears to be suitable for clinical use Compared with the methods tested so far (T1, diffusion, proton resonance), this method has the special advantage of not being very susceptible to artefacts. The competing methods of non-invasive thermometry using magnetic resonance tomography/spectroscopy will be investigated next.

Artifacts↗
PubMed1997

[Intra-abdominal schwannoma. Diagnosis and surgical therapy].

We report three patients who were operated on because of an intraabdominal schwannoma between February 1991 and October 1994 in our department. In the first case, a benign gastric schwannoma was treated by a distal gastric resection (Billroth II); the main symptom was gastric bleeding. In the second case, a malignant duodenal schwannoma with liver metastasis was treated by wide en-bloc resection of the tumor including retroperitoneal lymphadenectomy and an anatomical resection of the right lobe of the liver. A metachronous metastasis of the liver, appearing 7 months postoperatively, was treated by intraparenchymatous laser coagulation; a local recurrence, appearing 19 months postoperatively, led to another tumor resection. The main symptom was a palpable intraabdominal mass in this case. In the third case, a malignant schwannoma of the abdominal wall was resected in fragments in another clinic. Six months later a local recurrence with infiltration of the liver appeared in spite of postoperative radiation and was resected en bloc. Early peritoneal sarcomatosis was apparent at that time. Postoperative chemotherapy did not prevent quick progression of the tumor. The patient died 18 months after the first operation. The clinical presentation, differential diagnosis and operative strategy for benign and malignant intraabdominal schwannomas are discussed.

Abdominal Neoplasms↗