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Biomedical subjects

E Bauer

Publications and source records attributed to E Bauer.

251 records · Page 14Linked to original sources
PubMedDate not supplied

Oxidation of benzo[a]pyrene by recombinant human cytochrome P450 enzymes.

The oxidation of benzo[a]pyrene (B[a]P) was examined using reconstituted systems prepared with recombinant human cytochrome P450 (P450) enzymes 1A1, 1A2, 2C8, 2C10, 2E1, and 3A4 and with microsomes prepared from Saccharomyces cerevisiae expressing recombinant human P450s 2C8, 2C9, and 2C18. Products measured by HPLC included the 3- and 9-phenols, the 4,5-, 7,8-, and 9,10-dihydrodiols (detected in the presence of epoxide hydrolase), and products in the polar fraction eluting immediately after the void volume. The most active enzyme in all reactions was P450 1A1. P450 3A4 and P450 1A2 formed appreciable amounts of several of the products, including the 3-phenol. P450 2C enzymes and P450 2E1 formed relatively low amounts of all B[a]P products. Consideration of these patterns along with knowledge of levels of expression of the P450s in human tissues and previous results with microsomes leads to the conclusion that P450 1A1 should dominate the oxidation of B[a]P in tissues where it is present and inducible. In human liver the level of P450 1A1 is low and P450 3A4, P450 2C subfamily enzymes, and P450 1A2 probably all contribute. Of the human P450s considered here, P450 1A2 was the most active hepatic enzyme forming the 7,8-dihydrodiol. 7,8-Benzoflavone stimulated the oxidation of B[a]P by P450 3A4 and inhibited the oxidations catalyzed by P450 1A2. The extent of inhibition of P450 1A1 was less (than with P450 1A2), probably due to the rapid oxidation of 7,8-benzoflavone by P450 1A1. The major 7,8-benzoflavone product appears to be the 5,6-oxide.

Benzo(a)pyrene↗
PubMedDate not supplied

[Efficacy of MRI--whole spine image in diagnosis of vertebral metastases--results of a prospective study].

AIM: To prospectively investigate the outcome efficacy of whole spine MRI for diagnosis and treatment in patients with suspected metastases of the spine. METHODS: All patients older than 50 years with newly diagnosed back pain and/or newly diagnosed spine-related neurological symptoms without a diagnosis by other imaging modalities were accepted in this study. A whole spine MRI and a detailed MRI per spine region with suspicious lesions were performed using a Siemens Magnetom Expert 1.0 Tesla machine. Outcome efficacy was determined by assessing further therapy and result for the patient. RESULTS: In all 15 patients of the year 1999 whole spine MRI allowed us to determine the definite diagnosis and treatment. Plain X-ray and 99mTc bone scanning gave a diagnostic suspicion but no definite diagnosis or therapeutic consequence. CONCLUSIONS: MRI of the spine including whole spine images allows clear cut decision making in diagnosis and treatment of cases suspicious for metastatic disease of the spine. Careful history taking and clinical examination provide enough information to opt for whole spine MRI as the first choice investigation. This will provide maximum benefit to the patient and avoid examination cascades.

Aged↗
PubMedDate not supplied

[Can TOF MRA replace duplex and Doppler sonography in preoperative assessment of the carotid arteries? A prospective comparison and review of the literature].

AIM: To examine the quality and usefulness of time-of-flight MR-angiography and duplex-doppler sonography, respectively, in assessment of the extracranial arteries before cervical spine operations. METHODS: Patients scheduled for operations of the cervical spine had an MRI plus TOF as well as a duplex and Doppler scan. At the time of the examination the radiologist and the neurologist in charge were blinded for the study. Endpoints were not only the accuracy of the procedures but more so which method improved the preoperative process most. RESULTS: Twenty patients were examined so far. Only in one case did the result differ when a complete occlusion diagnosed sonographically was judged as a severe stenosis on MRA. One patient did not tolerate the MRA for the extra 5 minutes necessary, therefore a contrast-enhanced MRA was performed. MRA eased the preoperative process as imaging of the pathology and the carotids were realised in one step. The costs were slightly higher for MRA than for duplex-doppler sonography. CONCLUSION: TOF-MRA can replace the duplex-doppler examination in the preoperative assessment of the carotids and has the potential to streamline the preoperative time schedule. Similar to duplex and doppler, in order to be accurate enough the method requires a high degree of expertise from the radiologist.

Aged↗
PubMedDate not supplied

Computer users' postures and associations with workstation characteristics.

This investigation tested the hypotheses that (1) physical workstation dimensions are important determinants of operator posture, (2) specific workstation characteristics systematically affect worker posture, and (3) computer operators assume "neutral" upper limb postures while keying. Operator head, neck, and upper extremity posture and selected workstation dimensions and characteristics were measured among 379 computer users. Operator postures were measured with manual goniometers, workstation characteristics were evaluated by observation, and workstation dimensions by direct measurement. Considerably greater variability in all postures was observed than was expected from application of basic geometric principles to measured workstation dimensions. Few strong correlations were observed between worker posture and workstation physical dimensions; findings suggest that preference is given to keyboard placement with respect to the eyes (r = 0.60 for association between keyboard height and seated elbow height) compared with monitor placement with respect to the eyes (r = 0.18 for association between monitor height and seated eye height). Wrist extension was weakly correlated with keyboard height (r = -0.24) and virtually not at all with keyboard thickness (r = 0.07). Use of a wrist rest was associated with decreased wrist flexion (21.9 versus 25.1 degrees, p < 0.01). Participants who had easily adjustable chairs had essentially the same neck and upper limb postures as did those with nonadjustable chairs. Sixty-one percent of computer operators were observed in nonneutral shoulder postures and 41% in nonneutral wrist postures. Findings suggest that (1) workstation dimensions are not strong determinants of at least several neck and upper extremity postures among computer operators, (2) only some workstation characteristics affect posture, and (3) contrary to common recommendations, a large proportion of computer users do not work in so-called neutral postures.

Adult↗
PubMedDate not supplied

Vasopressin and renin in high output heart failure of rats: hemodynamic effects of elevated plasma hormone levels.

We studied the hemodynamic effects of vasopressin and the renin-angiotensin system in an animal model of high output heart failure in conscious rats (aorto-caval fistula). We found significantly elevated levels of plasma renin concentration (p less than 0.025), norepinephrine (p less than 0.02), and up to 4 to 5 times higher values of vasopressin (p less than 0.002) in the rats with heart failure as compared with control animals. In contrast to the control rats that had a normally functioning osmoreceptor system, we found an inverse relationship between plasma osmolality and arginine vasopressin in the rats with heart failure in association with edema. Using a specific antagonist of the pressor activity of vasopressin, we found no significant effect on heart rate, mean arterial pressure, cardiac output (thermodilution), and peripheral vascular resistance in the control animals and in the rats with aorto-caval fistula. Captopril resulted in a significant fall of mean arterial pressure in the rats with shunt (p less than 0.001). The coincidence of high values of vasopressin and, in a number of animals, low plasma osmolalities and edema suggests a role of vasopressin in the formation of edema and in the development of "dilutional hypo-osmolality."

Animals↗
PubMedDate not supplied

[Biliary, renal and fecal elimination and distribution of gold after a single oral administration of auranofin, quantified by the instrumental neutron activation analysis method].

Three days after cholecystectomy, seven patients received a single dose of auranofin (5 tablets Ridaura = 4.35 mg gold). At defined time points thereafter the gold content in samples of blood, plasma, urine, bile, and feces was determined by instrumental neutron activation analysis (INAA). Maxima of the mean gold concentrations in blood (140 +/- 42 ng/ml) and plasma (173 +/- 54 ng/ml) are found 2 h after oral administration of the antirheumatic agent, after 16 h in urine (43 +/- 28 ng/ml) and bile (65 +/- 50 ng/ml), and after 24 h in erythrocytes (greater than 200 ng/ml). The mean terminal half-lives are 7.6 days (blood), 15 days (plasma), 5 days (erythrocytes), and 6.5 days (bile). The cumulative biliary gold excretion within 8 days after the administration of auranofin was 1.6%, compared with 4% and 40% for renal and fecal elimination, respectively. The gold concentration in plasma is always higher than that in bile. There is a close correlation between the areas under the concentration curves (AUC) in bile and plasma (r = 0.864).

Administration, Oral↗