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Biomedical subjects

C Burri

Publications and source records attributed to C Burri.

At least 19 recordsLinked to original sources

An in vitro bioassay for quantification of melarsoprol in serum and cerebrospinal fluid.

A biological assay was developed for measuring melarsoprol in serum and cerebrospinal fluid of patients with human African trypanosomiasis. Trypanosomes were cultivated in microtiter plates for 72 hours with melarsoprol (Mel B) in concentrations of 1.25 micrograms/ml to 2.2 ng/ml. The minimum inhibitory concentration of Mel B for a reference Trypanosoma brucei rhodesiense clone was determined by microscopical examination. Samples of serum or cerebrospinal fluid were incubated under the same conditions and the highest dilution determined which caused death of all trypanosomes. The melarsoprol concentration of the sample was then calculated using the sample dilution and the determined minimal inhibitory concentration of the trypanosome population used for the assay. The test was validated using a number of reference samples and it was used for melarsoprol determination in serum- and cerebrospinal fluid samples taken from two treated patients. A sample size of 100 microliters was sufficient to perform the assay. The lower detection limit was 9 ng/ml (22.6 nmol/ml). The assay has potential for measuring other trypanocidal drugs in body fluids.

Animals

Total "internal" hemipelvectomy.

Several authors have described resections of tumorbearing parts of the pelvis including reconstructive plastic surgery. With extensive tumor growth present mutilating hemipelvectomies often have been the last resort. Even the most sophisticated prostheses hardly ever enabled the patients to walk again. We have therefore performed total "internal" hemipelvectomies in three cases. The necessary substitute consisted of half a pelvis made of polyacetal resin produced from a given model. The model's measures and shape was established by computer tomograms thus resulting in an individually shaped pelvis half. The operative procedure aims at the maintenance of osseous muscular insertions and origins and their reconstruction. Utmost care has to be taken in avoiding damage to nerves and vessels. Fixation of the implant is performed by screws aiming through the sacroiliac joint into ala and corpus of the sacrum and corticocancellous grafts incorporated in the implant. The symphyses are united by means of plate fixation. The hip joint is substituted by a total prosthesis. With the procedure described we have managed three cases of extensive malignant tumors of the pelvis. One patient suffered a nerve lesion and skin necrosis with infection. The two remaining patients are capable of weight-bearing and standing on the inflicted leg alone.

Adolescent

[Technical aspects of parenteral feeding].

The following approaches to the caval vein are applicable: Vena saphena, respectively femoralis, vena basilica, subclavia respectively anonyma and vena jugularis. Based on collective studies from literature and own experience the puncture of the internal jugular vein is recommended. The approach via the veins of lower extremities is to be used no more on adults. Numerous complications, however, are independent of the approach. They may be caused by the catheter model applied or by poor application technique. A model of our own was developed presenting siliconized polyethylene and a removable needle as main features. The material of the catheter proved to be neutral towards tissue experimentally and clinically. As compared to PVC the rate of inflammation and thrombosis was significantly decreased. Finally the removable split needle prevents catheter embolization with its grave consequence.

Bacterial Infections

[Experimental studies on the biomechanics of the lateral ligaments of the knee joint].

Measurements of absolute strain and stress on collateral ligaments of human knees were made with two new measuring cells. The medial collateral ligament was found to have three functional different parts, the most important of which was the ventral. During motion of the knee, tensile forces amounted to about 20 N when the lateral ligament was in extension and the medial ligament in full flexion. Moments of abduction and adduction increased strain and stress manyfold.

Biomechanical Phenomena

[Studies on the intra-osseous fastening of alloplastic ligament substitutes in sheep using carbon fibers].

The alloplastic replacement of the medial collateral ligament of the knee of sheep by carbon fibers gave a strength comparable with the natural ligament. Coating of the fibers, e.g., with epoxy resin, leads to a reduced integration of the implant into the tissues. Physical and histologic results together with the intraosseus anchorage show that pure carbon fibers are a suitable material for alloplastic ligament replacement.

Animals

[In vitro study of isolated chondrocytes concerning the prognosis of transplanted cartilage].

In order to find out reliable criteria to conclude on the prognosis of transplanted cartilage the quality of isolated rabbit chondrocytes was assayed in vitro. Using a semisolid medium a culture system is introduced, which is able to detect colony forming units of chondrocytes. Furthermore their proliferative and differentiating capacity was investigated. Colony formation in vitro follows a strict dose response relationship. An inverse relationship was observed between the age of the donor and the colony incidence in vitro. Cells from neonatal cartilage could be induced to grow as fibroblastic colonies in the presence of conditioned medium from fibroblastic monolayer cultures. No effect, however, could be observed with chondrocyte derived conditioned medium.

Age Factors