Biomedical subjects

C Langen

Publications and source records attributed to C Langen.

4 recordsLinked to original sources

PubMed1994

Semi-automatic external defibrillation.

Malignant arrhythmia, which is responsible for most of the out-of-hospital cardiac arrests, is ventricular fibrillation (VF). The best treatment of VF is a controlled electric shock on the chest administered in a short delay. The emergency medical technicians (EMTs) qualified to carry out this treatment in Belgium and in districts often succeed in arriving on the spot 8 minutes earlier than the people of the Service Mobile d'Urgence et de Réanimation (SMUR). The delegation of defibrillation to ambulance crew members however implies a specific teaching, training and a medical control. The Brussels experience shows that semi-automatic external defibrillation by EMT-Ds (SAED) is feasible when criteria for applying SAED in the pre-hospital phase are applicable.

Aged↗

PubMed1991

Assessment of proliferative activity in carcinomas of the human alimentary tract by Ki-67 immunostaining.

The monoclonal antibody (MAb) Ki-67, which is directed against a proliferation-associated nuclear antigen, was used to measure tumor proliferation in 165 carcinomas of the esophagus, stomach, colon and rectum with an indirect immunoperoxidase technique. The percentage of Ki-67-positive tumor cells (Ki-67 index) was evaluated with the point-counting method. The Ki-67 index in gastric cancers (mean, 24.8%; standard deviation, 11.1%) was significantly lower than in tumors of the esophagus (35.7 +/- 12.6%), colon (37.6 +/- 15.2%), and rectum (34.3 +/- 16.4%). A wide range of the Ki-67 index (5.9-75.3%) could be observed within the various tumor types. In recurrent colorectal carcinomas, the Ki-67 index significantly increased to 51.9%. The Ki-67 index was independent of pathologic (e.g., TNM-stage, grading, tumor volume, tumor site) and clinical variables (age and gender of the patients). A marked heterogeneity of Ki-67 expression within different tumor stages was noted. Statistically significant regional variations in tumor proliferation existed between different areas within the same tumor.

Adult↗

PubMed1989

Critical evaluation of histochemical and immunochemical methods for the demonstration of vascular supply in rectal and oesophageal cancer.

The vascularisation of rectal and oesophageal carcinomas and of normal mucosa was studied using histochemical and immunohistochemical methods. Endothelial cells were stained for alkaline phosphatase (AP) using an azo-dye procedure. Histochemical results were compared with the immunohistochemical identification of endothelial cells using the monoclonal antibody BW 200 recognising an epitope restricted to human endothelial cells. In the AP experiments the simultaneous reactivity of stromal tissue often precluded the exact evaluation of tumour blood vessels. Immunohistochemistry facilitated the identification of vessels in neoplastic tissues and allowed a quantitative analysis of vascular volume by means of point-counting. Vascular volumes of normal tissues exceeded those of tumours by a factor of 1.6. This immunohistochemical technique has potential application in studying the importance of tumour blood supply in man, especially in relation to radiotherapy.

Antibodies, Monoclonal↗

PubMed1987

Application of stable isotope methodology to study the pharmacokinetics, bioavailability and metabolism of nitrendipine after i.v. and p.o. administration.

1. The pharmacokinetics, bioavailability and metabolism of nitrendipine were studied in six healthy volunteers (three females, three males) using [13C4]-nitrendipine as a biological internal standard. In the first study the drug was administered simultaneously by the i.v. [13C4] and p.o. (solution) routes and in a second study two oral preparations (13C4-solution and commercial tablet) were administered, also simultaneously. 2. The mean terminal elimination half-life was 8.3 +/- 3.2 h (range 3.4 to 16 h) with no differences between the intravenous and oral route of administration. Total plasma clearance averaged 18.7 +/- 0.6 ml min-1 kg-1 and volume of distribution at steady state 5.4 +/- 2.4 1 kg-1. 3. Following oral administration of nitrendipine solution the percentage of dose absorbed was 88.4 +/- 16.0% based on urinary excretion of metabolites. Despite its almost complete absorption, absolute bioavailability of the solution was only 22.6 +/- 6.7% due to extensive presystemic elimination. The bioavailability of the commercial tablet relative to the solution was 82.2 +/- 20.3%. 4. Both after i.v. and oral administration the drug was extensively metabolized with less than 0.5% of the dose excreted as unchanged drug in urine. Cleavage of the two ester functions in position 3 and 5, respectively, to carboxylic acids and further hydroxylation of the methyl groups in position 2 and 6 of the pyridine ring to the corresponding hydroxymethyl carboxylic acids constituted the major urinary metabolites accounting for 35.0 +/- 16.5% (i.v.) and 32.8 +/- 20.4% (p.o.), respectively, of the dose administered. 5. Binding of nitrendipine to plasma proteins was high with a fraction unbound of only 0.02 +/- 0.012 (range 0.011 to 0.036).

Administration, Oral↗