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Biomedical subjects

B Kammer

Publications and source records attributed to B Kammer.

12 recordsLinked to original sources
PubMed2005

[Inflammatory diseases of the gall bladder and biliary system. I. Imaging--cholelithasis--inflammation of the gall bladder].

Cholelithiasis is the most common affliction of the gallbladder and biliary tract. Including its complications, gallstone disease represents the basis for cholecystitis and cholangitis in the majority of cases. Inflammatory diseases of the biliary system are divided into acute and chronic forms originating from the gallbladder as well as from the biliary tract. Although acute calculous cholecystitis is the most common form, gangrenous, and emphysematous inflammation of the gallbladder as well as gallbladder empyema are included in this group of diseases. In the chronic forms, calculous and acalculous inflammation is also differentiated. Recent developments in cross-sectional imaging in sonography, computed tomography, and magnetic resonance imaging offer numerous tools for depicting the biliary system with high diagnostic accuracy. Invasive imaging modalities of the biliary system are mainly used for therapeutic aspects.

Biliary Tract Diseases↗
PubMed2005

[Inflammatory diseases of the gall bladder and biliary system. II. Acute and chronic inflammation of the biliary system--primary biliary cirrhosis].

Inflammatory diseases of the biliary tract are divided into acute and chronic forms. Acute inflammation of the biliary tree is ascending cholangitis. Among chronic forms of the disease, primary sclerosing cholangitis, parasitic infection of the biliary tract, AIDS cholangiopathy, and chemotherapy cholangitis are recognised. Primary biliary cirrhosis and chronic inflammation of the papilla are also categorized within this group of inflammatory diseases of the biliary tree. Cross-sectional imaging modalities, such as sonography, computed tomography and magnetic resonance imaging, offer numerous possibilities for depicting the biliary system with high diagnostic accuracy. In contrast to the gallbladder, invasive imaging modalities of the biliary tree are also used for diagnostic purposes in addition to their therapeutic aspects.

Acute Disease↗
PubMed1996

Biosynthesis of taxol: enzymatic acetylation of 10-deacetylbaccatin-III to baccatin-III in crude extracts from roots of Taxus baccata.

The biosynthesis of taxol is a multistep process. One intermediate reaction is the acetylation of 10-deacetylbaccatin-III (10-DAB) to baccatin-III, an assumed precursor of taxol. Here we describe the cell free acetylation of 10-DAB in crude extracts from roots of Taxus baccata saplings using 14C-or 3H-labeled acetyl-coenzyme A as the acetyl donor. The reaction is strictly dependent on the addition of 10-DAB and is specific for the 10-hydroxyl group of the taxane ring. Formation of radiolabeled baccatin-III was confirmed by co-chromatography of the labeled product with authentic baccatin-III in different TLC-systems and HPLC. Furthermore, the acetylation product showed an identical UV spectrum as authentic baccatin-III. Crude extracts from cambium of stems yielded three- to fivefold lower activity. This is in agreement with our finding that the taxol titer in roots was considerably higher than that in cambium.

Acetylation↗
PubMed1995

[Differential radiologic diagnosis of HIV-associated lung diseases].

In 1993 in Germany an estimated number of 50,000-70,000 individuals were infected with the human immunodeficiency virus (HIV), WHO estimations ranged up to 14 million HIV-positive individuals including 1 million children. AIDS-related diseases frequently occur in the lung. 65% of all AIDS-defining illnesses begin with life-threatening pulmonary infections. Most frequently HIV-positive patients present with Pneumocystis carinii pneumonia, followed by atypical mycobacteriosis, bacterial infections, Kaposi's sarcoma and non-Hodgkin lymphoma. The purpose of this article is to identify pulmonary HIV-associated diseases by focusing on radiological patterns and correlating them with clinical findings.

AIDS-Related Opportunistic Infections↗
PubMed1994

Dissolution of calcified gallstones. Part I. Correlation of in vitro dissolution kinetics in methyl tert-butyl ether with patterns of calcification by computed tomography.

RATIONALE AND OBJECTIVES: The authors evaluated the relationship between stone computed tomography (CT) attenuation patterns and the kinetics of dissolution with methyl tertbutyl ether (MTBE). METHODS: Single moderately and heavily calcified gallstones from 40 patients were selected from a gallstone library and classified for pattern of calcification by in vitro CT scan (dense, rim, core, and laminated). Each stone was placed in a 10-mL aliquot of MTBE for 24 hours. Stone residue was blotted dry and weighted at 8, 16, and 24 hours. Results were normalized with respect to stone size. RESULTS: Only 1 of 40 (4%) specimens dissolved to particulate matter that was smaller than 2 mm. All (6 of 6) stones that were densely calcified showed virtually no dissolution. The rate of gallstone dissolution varied temporally within the rim, core, and laminated stone categories and was related to the composition of the layer exposed to the solvent at any given time. CONCLUSION: The success and rate of dissolution may be predicted by the pattern of calcification as determined by computed tomography (CT).

Cholelithiasis↗
PubMed1994

Dissolution of calcified gallstones. Part II. Evaluation of edetic acid preparations for dissolution of residue after in vitro methyl tert-butyl ether treatment.

RATIONALE AND OBJECTIVES: The authors assessed the potential of edetic acid (EDTA) preparations to dissolve the residue of calcified gallstones partially treated with methyl tert-butyl ether (MTBE). METHODS: Nineteen triplets (57 gallstones) were submitted to dissolution in EDTA, urea-EDTA, and an MTBE control for 48 hours after initial partial dissolution in MTBE for 24 hours. Results were compared with findings at specimen computed tomography and crystallographic analysis. All data were corrected for differences in stone size. RESULTS: In all three treatment groups (EDTA, urea-EDTA, MTBE), almost identical dissolution outcomes were observed within each triplet. Most triplets that dissolved displayed a laminated or a core-calcification pattern and consisted primarily of cholesterol. Specimens that dissolved poorly in all three groups displayed dense calcifications or thick calcified rims and were classified as pigment stones. CONCLUSION: Because no statistically significant differences in dissolution were found among the EDTA, urea-EDTA, and MTBE treatments, we conclude that EDTA preparations are not superior to the continued use of MTBE for dissolution of residue after initial MTBE treatment.

Chelating Agents↗
PubMed1994

Prediction of gallstone composition: synthesis of CT and radiographic features in vitro.

PURPOSE: To test a morphoradiographic algorithm designed to predict the composition of gallstones with use of computed tomography (CT) to define calcification patterns. MATERIALS AND METHODS: Two reviewers retrospectively evaluated the radiographic features of 120 separate in vitro specimens (59 radiopaque and 61 radiolucent), then classified the stones into several categories of composition with the algorithm. RESULTS: The most useful features for prediction of cholesterol composition were, in order of decreasing importance, stone shape, absence of dense calcification on plain radiographs, overall CT attenuation not higher than that of water, presence of a second generation of smaller stones, and a peripheral cover of calcification detected on CT scans of aging cholesterol stones. The greatest error occurred in distinction between stones with mixed composition (50%-79% cholesterol) and older stones with higher cholesterol content (80%-95% cholesterol). CONCLUSION: The range of qualitative CT appearances advances the possibility of predicting gallstone composition and potential outcome of nonsurgical treatment.

Bile Pigments↗
PubMed1991

Percutaneous contact dissolution of gallstones: complexity of radiologic care.

The clinical and technical considerations for successful gallstone dissolution with methyl tert-butyl ether (MTBE) are often underestimated. Patients are selected for MTBE therapy on the basis of a functioning gallbladder without evidence of acute inflammation or calcified stones at plain radiography. A transhepatic route is favored for percutaneous insertion of the cholecystostomy catheter because of the theoretic reduced frequency of bile leakage. MTBE is delivered manually through the catheter in a closed system, with dissolution times of 4-16 hours. After MTBE dissolution, residual debris in the gallbladder is present at follow-up sonography in up to 75% of patients. The high frequency of residual debris, the potential for stone recurrence, and the labor-intensive nature of MTBE therapy make its future uncertain, especially with the advent of laparoscopic cholecystectomy.

Cholelithiasis↗
PubMed1991

Optimal technique for detection of gallstones at injection cholecystography: in vitro analysis.

Injection cholecystography is often employed during invasive gallbladder procedures to determine the number of gallstones that are present. The authors undertook this study to define the optimal radiographic technique for performance of injection cholecystography. Condoms filled with 100 mL of contrast medium at four different iodine concentrations (30%, 15%, 7.5%, and 3.8% [wt/vol]) and containing up to five 4-mm-thick gallstones or a single 10-mm-thick gallstone were radiographed in a 20-cm-deep water bath by using four kilovolt peak settings (70, 80, 90, and 100 kVp). Images were read by three radiologists who were blinded to the radiographic technique. significantly (P less than .05) improved Decreasing iodine concentration significantly (P less than .05) improved detection of 4-mm-thick gallstones at a constant kilovolt peak setting. However, increasing the kilovolt peak setting while using the same concentration of contrast medium had no statistically significant influence on gallstone detectability, although radiologists did indicate a preference for the high-kilovolt peak technique. Results of the authors' experiments showed that for detection of small gallstones at injection cholecystography, use of a low-concentration contrast medium and a high kilovolt peak setting is the recommended radiographic technique.

Cholecystography↗
PubMedDate not supplied

Do computers teach better? A media comparison study for case-based teaching in radiology.

A prospective study was performed to better define the role of computers in teaching radiology to medical students. Two hundred twenty-five 3rd-year students were randomly assigned to one of four groups and exposed to 10 radiology cases as well as to a voluntary weekly radiology lecture. Group A used computer-based cases with interactive elements; group B used computer-based cases without interactive elements; group C used paper-based cases with interactive elements; and group D was not exposed to the cases and served as a control group. On a multiple-choice question test, groups A, B, and C showed significant improvement (+11.2%, +15.1%, and +13.0%, respectively), whereas group D did not (+0.6%). On an image interpretation test, group A showed the most improvement (+15.7% [P <.001]), followed by group B (+15.1% [P <.01]) and group C (+10.2% [P <.05]); group D showed no significant improvement (+8.5%). No significant differences in the learning outcome were found between the two interactive groups (computer based and paper based). Computer-based teaching with case studies (with or without interactivity) improves students' problem-solving ability in radiology.

Chi-Square Distribution↗