A DNA damage repair mechanism is involved in the origin of chromosomal translocations t(4;11) in primary leukemic cells.

Some chromosomal translocations involved in the origin of leukemias and lymphomas are due to malfunctions of the recombinatorial machinery of immunoglobulin and T-cell receptor-genes. This mechanism has also been proposed for translocations t(4;11)(q21;q23), which are regularly associated with acute pro-B cell leukemias in early childhood. Here, reciprocal chromosomal breakpoints in primary biopsy material of fourteen t(4;11)-leukemia patients were analysed. In all cases, duplications, deletions and inversions of less than a few hundred nucleotides indicative of malfunctioning DNA repair mechanisms were observed. We concluded that these translocation events were initiated by several DNA strand breaks on both participating chromosomes and subsequent DNA repair by 'error-prone-repair' mechanisms, but not by the action of recombinases of the immune system.

In vitro corrosion of titanium.

Titanium is used in dentistry for implants and frame work because of its sufficient chemical, physical and biological properties. The corrosion behaviour is from high interest to value biocompatibility. A static immersion test was undertaken with a titanium test specimen (30 mm x 10 mm x 1 mm, immersion time = 4 x 1 w, n = 3 for each series). The following parameters were investigated: specimen preparation, grinding, pH-value, different casting systems, comparison with CAD/CAM, influence of: chloride, thiocyanate, fluoride, lactate, citrate, oxalate, acetate. Atomic absorption spectroscopy was used to analyse the solutions weekly. The course of corrosion was investigated photometrically. Titanium reveals ion releases [(0.01-0.1) microg/(cm2 x d)] in the magnitude of gold alloys. There is little influence of grinding and casting systems in comparison with organic acids or pH value. The ion release increases extreme (up to 500 microg/(cm2 x d)) in the presence of fluoride. Low pH values accelerate this effect even more. Clinically, no corrosion effects were observed. Nevertheless it is recommended that it is best to avoid the presence of fluoride or to reduce contact time. In prophylactic fluoridation of teeth, a varnish should be used.

[Bacterial contamination as a complication of intravenous therapy in intensive care (author's transl)]. / Die bakterielle Kontamination als Komplikation der Infusionstherapie.

Intravenous infusion therapy has become an indispensible part of intensive care. Problems of bacterial contamination during this therapy are well known. To check on the possible routes of contamination we examined the infusion system in its several parts (infusion solution, infusion system, connection between infusion system and catheter and content of syringes). The highest rate of contamination was found at the connection between the infusion system and the catheter after use for 24 h (26.7%, 39 out of 146 probes); just at the beginning of the infusion we found bacterial growth in 7.1% (10 out of 141 probes). After injection of drugs into the system the infusion solution was contaminated in 1.9% (6 of 320 probes). The system for measuring the central venous pressure was contaminated in 2.7% (4 of 148 probes). At the end of infusion the infusion solutions were contaminated in 3.1% (9 of 287 probes). Different drugs in syringes in no case were contaminated. In most cases (59 probes) we found gram-positive bacteria (87.3%), in only seven cases (9.7%) gram-negative bacterias and in two cases Candida tropicalis. Our results show that the extrinsic or in use contamination plays the most important part in bacterial contamination of the infusion system. Infection control of intravenous therapy necessitates care in the hygienic standard adopted during the infusion and injection procedures.