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Biomedical subjects

J Wildberger

Publications and source records attributed to J Wildberger.

14 recordsLinked to original sources
PubMed2005

[Diagnostics and therapy for invasive fungal infections in an intensive care unit].

Invasive fungal infections are associated with a high mortality and have been increasing in incidence over the last few decades. Candidemia and, less commonly, invasive pulmonary aspergillosis are the most relevant fungal infections in critical care medicine. Risk factors for systemic Candida infections are the use of broad-spectrum antibiotics, a prolonged stay in an intensive care unit and gastrointestinal injury or surgery. Invasive aspergillosis usually occurs in immunocompromised patients. The diagnosis of invasive fungal infections remains challenging. The therapeutic spectrum includes fluconazol, conventional and liposomal amphotericin B, and the recently introduced agents caspofungin and voriconazol. For rational and cost-effective use, the clinician requires precise knowledge of the indications and limitations of these agents. This review focuses on the diagnostic and therapeutic options in severe Candida infections and invasive aspergillosis.

Acute Disease↗
PubMed2005

[On the way to isotopic spatial resolution: technical principles and applications of 16-slice CT].

The broad introduction of multi-slice CT by all major vendors in 1998 was a milestone with regard to extended volume coverage, improved axial resolution and better utilization of the tube output. New clinical applications such as CT-examinations of the heart and the coronary arteries became possible. Despite all promising advances, some limitations remain for 4-slice CT systems. They come close to isotropic resolution, but do not fully reach it in routine clinical applications. Cardiac CT-examinations require careful patient selection. The new generation of multi-slice CT-systems offer simultaneous acquisition of up to 16 sub-millimeter slices and improved temporal resolution for cardiac examinations by means of reduced gantry rotation time (0.4 s). In this overview article we present the basic technical principles and potential applications of 16-slice technology for the example of a 16-slice CT-system (SOMATOM Sensation 16, Siemens AG, Forchheim). We discuss detector design and dose efficiency as well as spiral scan- and reconstruction techniques. At comparable slice thickness, 16-slice CT-systems have a better dose efficiency than 4-slice CT-systems. The cone-beam geometry of the measurement rays requires new reconstruction approaches, an example is the adaptive multiple plane reconstruction, AMPR. First clinical experience indicates that sub-millimeter slice width in combination with reduced gantry rotation-time improves the clinical stability of cardiac examinations and expands the spectrum of patients accessible to cardiac CT. 16-slice CT-systems have the potential to cover even large scan ranges with sub-millimeter slices at considerably reduced examination times, thus approaching the goal of routine isotropic imaging.

Cardiovascular Diseases↗
PubMed2003

[MR-urography and CT-urography: principles, examination techniques, applications].

MR-urography (MRU) and CT-urography (CTU) provide refined imaging of the upper urinary tract not achievable with conventional intravenous urography (IVU). The traditional MR-urographic technique utilizes unenhanced, heavily T2 -weighted turbo spin-echo sequences for obtaining static fluid images of the urinary tract independent of the excretory renal function. T2 -weighted MR-urograms have proved to be excellent in visualizing the dilated urinary tract, even in non-excreting kidneys. In contrast, T1 -weighted MRU reflects the excretory renal function and displays the urine flow through the upper tract after renal excretion of an intravenously administered gadolinium chelate. The gadolinium-enhanced urine is visualized with fast T1 -weighted 3D-gradient-echo sequences. The combination of gadolinium and low-dose furosemide (5 - 10 mg) is the key for achieving a uniform distribution of gadolinium in the collecting system and for avoiding susceptibility artifacts (T2*-effects) in the urine. T1 -weighted excretory MRU provides impressive urograms of both non-dilated and obstructed collecting systems in patients with normal or moderately impaired renal function. Multislice-CT-urography (MS-CTU) is also an excretory urography like T1 -weighted MRU. Furthermore, MS-CTU can be combined with low-dose furosemide for accelerated passage of excreted contrast material obviating the need for abdominal compression. CT-urography is limited by its radiation burden and the nephrotoxicity of radiographic contrast media. Combining MRU or MS-CTU with conventional MRI or CT offers several applications, e.g., diagnosis of intrinsic and extrinsic tumors. Meanwhile, MRU has replaced IVU in pediatric uroradiology and is also recommended for the assessment of renal transplants. MS-CTU may provide valuable information in chronic urolithiasis, especially if associated with a distorted urinary tract anatomy. Both MRU and MS-CTU will play an important role in modern uroradiology.

Adolescent↗
PubMed2001

Analysis of FDG uptake with hybrid PET using standardised uptake values.

The standardised uptake value (SUV) has been used as an index of glucose metabolism to classify malignant tumours. To date, calculation of SUVs has been restricted to dedicated PET. The aim of this study was to investigate the feasibility of SUV calculation with attenuation-corrected hybrid PET, applying a singles count rate-related calibration method. Calibration factors for hybrid PET at different singles count rates were determined by phantom studies. SUVs were determined for hot spheres in a phantom study as well as for 68 malignant lesions in 56 patients. Recovery coefficients calculated for hot spheres were applied to SUVs of malignant lesions to correct for partial volume and recovery effects. At a sphere-to-background ratio of 10:1, SUVs of spheres with diameters from 34 to 16 mm varied from 5.0 to 1.5 for hybrid PET, and from 8.0 to 4.3 for dedicated PET. SUVs of malignant lesions calculated by hybrid and dedicated PET showed a strong correlation (r=0.95, P<0.001), with a mean percentage difference of 36%. SUVs calculated by hybrid PET were significantly lower than SUVs calculated by dedicated PET (6.2+/-4.3 vs 8.5+/-5.3, P<0.001). Application of recovery coefficients revealed an SUV of 12.2+/-7.3 for hybrid PET versus 10.8+/-6.3 for dedicated PET, with a significant reduction in the mean percentage difference (22%, P<0.01). In conclusion, singles count rate-related calibration factors allow calculation of SUVs with hybrid PET for lesions with a diameter larger than 15 mm. Correction for partial volume and recovery effects is needed to improve the agreement of SUVs of lesions determined by hybrid PET and dedicated PET.

Calibration↗
PubMed2000

Clonal chromosome abnormalities in enchondromas and chondrosarcomas.

We report cytogenetic findings in short-term cell cultures from five enchondromas and four chondrosarcomas. Clonal chromosome aberrations were found in one case of enchondroma, and in all cases of chondrosarcoma. The only enchondroma with nonrandom abnormalities had a reciprocal t(8;17)(q23;p13), and monosomies 9, 19, and/or 22. In contrast to the few karyotypic findings in one of five enchondromas, the four chondrosarcomas were commonly characterized by cytogenetic heterogeneity, with a tendency for increasing karyotypic complexity in higher grade tumors. Two cases, one grade III and one metastasizing grade II chondrosarcoma, revealed hypodiploid stem- and sidelines with loss of chromosomes 6, 10, 13, 14, and 22, as common chromosomal abnormalities, suggesting a distinct karyotypic pattern in a subset of biologically aggressive chondrosarcomas.

Adolescent↗
PubMed1999

Long-term survival after diagnosis of hepatic metastatic VIPoma: report of two cases with disparate courses and review of therapeutic options.

This report describes two patients with pancreatic cholera caused by vasoactive intestinal polypeptide (VIP)-producing tumors, which originated in the pancreas and showed metastases in both hepatic lobes at time of diagnosis. However, the two tumors displayed remarkably disparate clinical courses. Due to the protracted but progressive course over more than 10 years, a multifaceted therapeutic approach was performed to control symptoms and to improve quality of life. The long-acting somatostatin analog octreotide was the most effective treatment for relieving symptoms and correcting fluid and electrolytes disturbances. The effects of complementary treatments, including systemic chemotherapy and hyperselective chemoembolization, as well as concurrent application of octreotide and prednisolone or interferon with respect to clinical symptoms, VIP levels, and tumor growth are reviewed. Our experience, although small, emphasizes the need for an expert, well-planned, adaptive, and multidisciplinary approach in the care of these complex patients.

Antineoplastic Agents, Hormonal↗
PubMed1999

Mechanical thrombectomy in hemodialysis access shunts using a 5F pigtail rotation catheter. In vitro and in vivo investigations.

RATIONALE AND OBJECTIVES: To evaluate the feasibility of mechanical thrombectomy in occluded hemodialysis access shunts by using a newly developed 5F pigtail rotation catheter. METHODS: Thrombosed hemodialysis access shunts were simulated by clotted bovine blood in silicone tubing (diameter 6 mm). After retrograde and antegrade sheath placement (6F), mechanical fragmentation was performed using a 5F rotatable pigtail device. Average tube length was 27 to 47 cm; average thrombus weight was 5 to 11.9 g (8.2 +/- 1.59). Clinical application involved six patients with fresh shunt occlusions (three Brescia-Cimino shunts, three Gore-Tex shunts). RESULTS: Using the in vitro setup, the device was able to restore a continuous lumen within 10 minutes with no remaining wall-adherent thrombi. The average amount of particles in the effluent was 3.0 g (2.0 to 3.9) for particles < or = 1.0 mm and 0.67 g (0.44 to 0.96) for particles > or = 0.2 mm wet weight; (compared with initial thrombus weight, 30.7% and 1.1%, respectively). Clinically, all six hemodialysis access shunts were successfully recanalized. Technical problems did not occur. There were no clinical symptoms indicating pulmonary embolism in any of the treated patients. CONCLUSIONS: In our experimental setup as well as under clinical conditions, effective treatment of occluded hemodialysis access sites was achieved. The pigtail rotation device is an easy-to-handle, inexpensive alternative to mechanical thrombus fragmentation in occluded hemodialysis access shunts. The rate of emboli in the effluent vein of approximately one third of the initial thrombus weight must be taken into consideration in frequent intraindividual use of this technique.

Adult↗
PubMed1998

Solitary enchondroma with clonal chromosomal abnormalities.

We report a case of a solitary enchondroma located in the head of the left fibula in a 50-year-old patient and present the findings of histopathologic investigation and cytogenetic analysis. The tumor revealed simple karyotypic abnormalities with t(8;17)(q23;p13) and loss of chromosomes 9, 19, and 22 as clonal chromosomal changes. Only a few enchondromas with chromosome aberrations have been published previously; nevertheless, it appears that benign and malignant cartilaginous tumors may have similar chromosomal abnormalities.

Bone Neoplasms↗
PubMed1998

Is prostate-specific antigen a reliable marker of bone metastasis in patients with newly diagnosed cancer of the prostate?

OBJECTIVE: Staging in patients with newly diagnosed cancer of the prostate has significant ramifications in the management of the disease. At present, measurement of serum prostate-specific antigen (PSA) concentration and radionuclide bone scintigraphy are two important procedures in the metastatic work-up of these patients. We evaluated the efficacy of PSA as a staging marker to discriminate prostate cancer patients with and without bone metastases. METHODS: In a retrospective study, 359 prostate cancer patients with (n = 40) and without (n = 319) bone metastases were analyzed. In all patients the initial PSA measurement as well as the radionuclide bone scan were evaluated. RESULTS: Patients without bone metastases demonstrated a median serum PSA concentration of 12 ng/ml, whereas those with bone metastases revealed a median serum PSA concentration of 59 ng/ml, with 7 patients demonstrating a serum PSA concentration of < 10 ng/ml. This resulted in a negative predictive value of 96%. In addition, only 40% of these patients with bone metastases demonstrated a serum PSA concentration of > 100 ng/ml, which resulted in a positive predictive value of 50%. CONCLUSION: The serum PSA concentration seems only to provide limited information with regard to the presence of bone metastasis in patients with newly diagnosed cancer of the prostate. We therefore question whether a staging radionuclide bone scan may be omitted in patients with a serum PSA value of < 10 ng/ml.

Adenocarcinoma↗
PubMed1997

Right atrial silicone catheters as angioaccess for hemodialysis with special emphasis to their complications.

Right atrial silicone catheters (RASCs) serve as temporary angioaccess in hemodialysis (HD) patients. In a retrospective study of the years 1989 to 1996 we analyzed catheter-related complications, and tried to define patients at special risk for complications. We compared our results with published data on RASCs and percutaneous catheters. In 73 patients older than 64 (mean age 76) years with severe comorbidity 109 single lumen RASCs, type Demers, were implanted. Fifty-five similar catheters implanted in 44 younger patients (mean age 53) with a comparable severe comorbidity were used as controls. In the older patients the mean indwelling time was 157 (1-995) days, median 98 days, in the younger patients 135 (1-623) days, median 61 days. Early complications that led to RASC removal within one week after implantation were kinking, formation of a narrow loop, perforation, infected hematoma, and immediate clotting. Reasons for removal of the RASC after a longer period were infection, occlusion, and dislocation. In the old age group a great proportion (40%) of patients died with functioning RASC. In the literature RASCs are superior to percutaneous (Shaldon) catheters as temporary angioaccess for HD with respect to both better longevity and fewer complications such as venous stenoses or occlusions or infections. This is in accordance with our experience. However RASCs have complications, especially in the high risk groups of diabetics and patients with malignancies.

Aged↗
PubMed1991

[Transfemoral extraction of a knotted Swan-Ganz catheter using an F24 dilator].

We report on the successful transfemoral extraction of a Swan-Ganz catheter twice knotted in a patient's heart. The extraction was performed with a Dormia basket and removed via a 24F dilatator which was placed in the femoral vein. The Swan-Ganz catheter had been placed in a 67-year old patient after Whipple's operation. The technical procedure of the catheter removal is described and the advantages are discussed.

Aged↗
PubMedDate not supplied

Treatment of renal cancer patients with gemcitabine (2',2'-difluorodeoxycytidine) and interferons: antitumor activity and toxicity.

Combined therapy of gemcitabine with interferons on patients with histologically confirmed metastatic renal cell carcinoma is reported. Patients had an unfavourable disease due to documented tumor progression after various interferon-alpha-based immunotherapy (26 weeks on average). The median number of metastatic sites was 6.1 per patient and 78% of the patients exhibited >/= 4 lesions. Nine evaluable patients received at least 6 doses of gemcitabine and 8 doses of interferon-gamma. Overall, therapy resulted in a remission rate of 15% (4 x partial response; 4 x minor response) for single measurable lesions (n=53). Remissions were more often found for lesions, that did not progress at baseline evaluation (n=30; OR: 20%), compared to 8.7% for sites in progression (n=23). However, as a result of therapy, 43.5% of the progressive lesions did not continue to progress. Although only one of nine patients finally overall achieved a minor remission and one patient a stable disease, the median time to tumor progression (6.1 months) and the median survival (13.5 months) was favourable. In conclusion, the combination of gemcitabine and interferon demonstrated cytotoxic and cytostatic effects on metastases of renal cell carcinoma at a tolerable toxicity, thus controlled clinical studies for first line therapy with gemcitabine and interferon are in progress.

Adult↗