Increased transcription decreases the spontaneous mutation rate at the thymidine kinase locus in human cells.

Transcription increases DNA repair efficiency and modulates the distribution of certain types of DNA damage. Furthermore, increased transcription level stimulates spontaneous mutation rate in yeast. We explored whether transcription level affects spontaneous mutation rate in human cells. We first developed two thymidine kinase (tk) inducible human cell lines using the Gal4-Estrogen receptor system. In our TK6i-G3 and G9 tk heterozygous cell lines, the active tk allele is linked to an inducible promoter element. Tk mRNA is induced following treatment with estrogen. Spontaneous mutation rate was significantly decreased in human cell lines after induction in contrast to the report in yeast. Thus, humans may have evolved different or additional mechanisms to deal with transcription related spontaneous mutagenesis.

Large deletions partially external to the human hprt gene result in chimeric transcripts.

We postulated that gene fusions sometimes occur in normal cells as a result of gene rearrangements as have been observed involving oncogene loci in tumours. To test this, we searched for fusion-gene transcripts in selected human T-lymphocyte large deletion mutations of the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene using the 3' rapid amplification of cDNA ends (RACE) technique. Aberrant hprt-containing transcripts were observed in seven out of 19 mutants (approximately 36%) indicating that a surprising number of these rearrangements code for processed mRNAs. RNA splicing and polyadenylation occurred downstream of the non-deleted hprt sequence in chimeric transcripts and the majority resulted from mutants with fusions of hprt into regions containing a repetitive element (Alu, LINE or microsatellite).

Physical mapping of the human hprt chromosomal region (Xq26).

The human hprt chromosomal region (Xq26) was physical-mapped using pulsed field gel electrophoresis (PFGE). This work involved: (i) the recovery of three new genomic DNA markers (DXS1327, DXS1328, and DXS1329), (ii) the ordering of new markers relative to 11 previously available hprt-linked markers by deletion mapping, and (iii) the completion of human T-lymphocyte PFGE Southern blots using the 14 Xq26 markers. A contiguous 1.5-Mb physical map of the region telomeric to hprt was determined. As this map identifies clusters of in vivo unmethylated rare-cutter restriction sites, potential CpG islands are revealed.

Pulsed field analysis of hprt T-cell large deletions: telomeric region breakpoint spectrum.

In order to determine a large deletion breakpoint spectrum, 25 independent hprt T-lymphocyte mutants with deletions extending from hprt into the telomeric or centromeric flanking chromosomal region were analyzed by pulsed field gel electrophoresis (PFGE). PFGE was used to determine deletion sizes which allowed localization of breakpoints external to hprt to specific chromosomal positions in mutants containing an intra-hprt breakpoint. A breakpoint spectrum based on 19 large deletion mutants is reported for the Xq26 chromosomal region telomeric to hprt. A potential cluster of breakpoints (4/19) was observed approximately 60 kb from hprt. In addition, maximum recoverable deletion size was at least 3.5 Mb. Three of the 25 mutants analyzed appeared to be complex deletion events.

Sensitivity of somatic mutations in human umbilical cord blood to maternal environments.

To assess the potential effect of maternal environments on human embryonic/fetal somatic mutation, we measured the frequencies of hypoxanthine-guanine phosphoribosyltransferase (HPRT, hprt gene), mutant T lymphocytes (Mf), and glycophorin A (GPA) variant erythrocytes (Vf) of both allele-loss (phi/N) and allele-loss-and-duplication (N/N) phenotypes in umbilical cord blood. The mean hprt Mf (1.40 +/- 1.11 x 10(-6), N = 66) and GPA Vf (phi/N 4.0 +/- 2.2 x 10(-6), N = 114; N/N 2.7 +/- 2.0 x 10(-6), N = 91) were significantly lower than those previously reported for adult populations. In addition, the hprt Mf was significantly higher than that of a published study of newborn cord blood samples from a geographically distant population (0.64 +/- 0.41 x 10(-6), N = 45, P < 0.01; t test, P < 0.01, Mann-Whitney U test). An examination of the demographic data from these two populations led to the sampling of 10 additional newborns specifically matched to the published study for maternal socioeconomic status. The hprt Mf (0.70 +/- 0.49 x 10(-6)) of this selected population was consistent with the published report and significantly lower than that of our initial population (P < 0.03, t test; P < 0.01, Mann-Whitney U test). These results indicate that there is an environmental effect related to maternal socioeconomic status on the frequency of embryonic/fetal somatic mutations. Molecular analyses of hprt mutants from this cohort with elevated Mf revealed a significant decrease in the relative contribution of gross structural mutations to the overall Mf (25 of 38, 66% vs. 34 of 41, 83%, P = 0.024, chi 2 test), suggesting that the higher Mf resulted from an elevated level of "point" mutations. No individual maternal demographic or environmental factor was identified as contributing more significantly than other any factor to the observed variability in hprt Mf or GPA Vf.

[Instability and impingement of the shoulder of the high performance athlete in overhead stress]. / Instabilität und Impingement an der Schulter des Leistungssportlers mit Uberkopfbelastung.

The present prospective study was performed on 89 competitive sportsmen (league players of handball, basketball, volleyball and water polo). The evaluation was based on information obtained from a review of training methods, a standardised anamnestic, physical and sonographic examination directed at pain, function, flexibility and all signs of impingement and instability of the shoulder counted in a score. The incidence of shoulder pain, which handicapped during training and play within the last 6 months was for water polo 60%, handball 40%, volleyball 25% and basketball 3.5%. Analysing these problems we found severe problems predominantly in handball, fewer in water polo or volleyball. According to data obtained from sports with throwing activity we found a high incidence of shoulder disorders. Using basketball players as a control group with less throwing activity our results would suggest that this mechanism seems to be the most important. The high incidence of severe disorders in handball players is additionally caused by traumatic injuries. Ultrasonography shows predominantly incomplete tears of the deep surface of the supraspinatus tendon near to the insertion with exception of the basketball players. Only in 5 shoulders (2.8%) we found the coincidence of clear signs of instability and subacromial pathology. The term "instability impingement" has not proved to be very helpful and has turned out to be far too diffuse to establish a diagnosis.

V(D)J recombinase-like activity mediates hprt gene deletion in human fetal T-lymphocytes.

Studies from several laboratories worldwide have developed a large database for in vivo hypoxanthine-guanine phosphoribosyltransferase gene mutations in human T-lymphocytes. Sufficient differences have been found thus far between the spectrum for spontaneous mutations in adults and that observed in the fetus to suggest fundamental differences in in vivo mutagenic mechanisms at these two life stages. In adults, only approximately 15% of hypoxanthine-guanine phosphoribosyltransferase mutations have structural alterations on Southern blots, while in the fetus 75% of mutations show alterations of which one-half are deletions of exons 2 and 3. We have now sequenced the breakpoint sites for these specific deletions in 18 mutant lymphocyte clones isolated from 13 normal newborns. Three classes of deletions were found. Each class had the same intron 1 breakpoint but a different intron 3 breakpoint. These mutations have all the signatures of a V(D)J recombinase-mediated event (a 5' consensus heptamer, 3' consensus heptamer and nonamer, nibbling, non-germline-encoded nucleotides, P-nucleotides). At the 3' breakpoint of the most common class (comprising 83% of the mutants) a perfect heptamer can be created by postulating a hairpin loop which could attain a Z-DNA configuration. This feature may indicate recombinase preference for certain DNA structures. These results implicate the V(D)J recombinase in illegitimate events causing mutation in this housekeeping gene during T-cell development. Inactivation of genes involved in the control of growth and differentiation (e.g., tumor suppressor genes) by this mechanism may have important implications for cancer development.

In vivo ionizing irradiations produce deletions in the hprt gene of human T-lymphocytes.

The hprt T-lymphocyte cloning assay, which detects mutations occurring in vivo in humans, has been used to examine mutants induced in patients receiving radioimmunoglobulin therapy (RIT) for cancer. Samples from 13 patients before treatment (controls) and 15 samples from 12 patients after treatment were studied for both mutant frequencies and molecular changes in the hprt mutant T-cell clones. Patients were studied up to 48 months after treatment. Post-RIT patients showed increased mutant frequencies as compared to pre-treatment values. T-cell receptor (TCR) gene analysis of mutant T-cell clones demonstrated that 84% arose independently, both pre- and post-treatment, which is the same proportion as seen in normal individuals. However, several individuals did show large sets of mutants with the same TCR gene rearrangement patterns. Molecular analysis of mutants demonstrated a greater proportion of mutations with hprt gene changes on Southern blots after RIT treatment than before (40% versus 20%). RIT increases the proportion of mutations with total rather than partial gene deletions or other gross structural changes compared to normal individuals or pre-treatment patients. These studies are defining the spectrum for radiation-induced hprt gene mutations in vivo in human T-lymphocytes.

Analysis of human HPRT deletion mutations with X-linked probes and pulsed field gel electrophoresis.

Because the human hprt gene is used in numerous mutation studies, it is important to fully characterize this gene. Therefore, our laboratory has undertaken to map the region around the hprt gene at band q26 of the human X chromosome. Utilizing hprt mutant T-cell clones isolated using the hprt clonal assay, which have deletions of all or part of the hprt gene, we have ordered 5 anonymous probes previously known to map in Xq26. Results suggest that this region includes between 460 kb and 18 Mb of DNA, which is at least 10 times the size of the hprt gene itself (43 kb). Pulsed field gel analysis of the region is underway to determine the exact distances between each of the anonymous probes and hprt and to determine deletion sizes in the mutant T-cell clones.

[Results of meniscus sutures in the framework of reconstruction in combined injuries of the knee joint: clinical aspects, arthrosonography, arthrography and computerized tomography]. / Ergebnisse von Meniscusnähten im Rahmen der Rekonstruktion von Kombinationsverletzungen des Kniegelenkes. Klinik, Arthrosonographie, Arthrographie und Computertomographie.

In spite of encouraging experimental results of suturing menisci in the not-vascularised area, even today in most of these cases subtotal resection will be done. The results of meniscal reconstruction in 15 patients with a longitudinal tear of the degeneration area as consequence of a combined injury of the knee joint are discussed. Only one patient suffered a postoperative rerupture. The others did not show any signs of continuing tears of the menisci during a study period of 18.7 months. Whereas in arthrography only in a few cases superficial notches, sign for a physiological recessus, were found, CT-scan as well as arthrosonography showed in large degree of correspondence change of density in the region of suture, which can be interpreted as a process of scar transformation. Thus it is recommendable to use suture of meniscus next to stabilizing measurements of injured knee-joint, even in the zone of degeneration.

[Functional anatomy of the upper ankle joint]. / Funktionelle Anatomie des oberen Sprunggelenks.

The ankle joint is regarded as a hinged joint with a range of motion of about 60 degrees. The shape of the trochlea tali varies, so the axis of rotation and the compensative movements of the fibula do. The ligamentous stabilizers of the medial side are thicker than the lateral ones. At the other hand, the lateral malleolus is more voluminous than the medial one. The lig. fibulotalare ant. is a reinforcement of the joint capsule, the lig. fibulocalcaneare has no connection to the jointcapsule, the lig. fibulotalare post. is partially running through the joint. In neutral- and plantarflexed position, the lig. fibulocalcaneare forms a groove which takes up the tendon sheat of the peroneal tendson. In dorsalextended position the tendons are pushed laterally by the tense ligament. This mechanism supports the peroneal tendon luxation in dorsal extension.

[Surgical therapy of fibular capsule-ligament rupture]. / Operative Therapie der fibularen Kapselbandruptur.

Different procedures for primary reconstruction of ruptured ligaments in fresh lateral ankle ligament injuries are reported. Selective local anesthsia of the nervus fibularis superficialis and suralis is considered a protective and low-risk method. In our opinion the primary surgical treatment of lateral ankle ligament ruptures is still the most adequate treatment, especially in sportsman.

[Recurrent shoulder dislocation. On the sports capacity following surgical therapy]. / Die rezidivierende Schulterluxation. Zur Sportfähigkeit nach operativer Therapie.

The traumatic dislocation is one of the most seen dislocations of great joints. In 70% it happens to patients during sports and between 20 and 60% of cases are followed by instability of the shoulder. An explorative study informs about case history, postoperative course and sports participation after surgical treatment of recurrent dislocations of the shoulder. Good results of sports participation can be achieved with early diagnostic and therapeutic procedures.

[Patellofemoral pressure and contact surface measurement in the 'hunter's hat patella'. Experimental studies of sagittal patella osteotomy]. / Patellofemorale Druck- und Kontaktflächenmessungen bei Jägerhutpatella. Experimentelle Untersuchungen zur sagittalen Patellaosteotomie.

One reason of the chondromalacia patellae is the functional incongruence due to a patellofemoral dysplasia like for example the so called hunter's hat deformity. As a curative treatment in those cases an osteotomy of the patella may be carried out. This operation shall improve the congruence of the articular surface as well as the stability of the patella. There are experimental studies describing the femoropatellar pressure situation in eight cases with a surgical induced hunter's hat patella after osteotomy. The results represent a significant increase of the opposing surfaces in the medial compartment and a more uniform distribution of the femoropatellar pressure.