Torus obstacle method as a wrapping approach of the deltoid muscle group for humeral abduction in musculoskeletal simulation.

Musculoskeletal models of the shoulder complex are valuable research aids to investigate tears of the supraspinatus and the resulting mechanical impact during abduction of the humerus. One of the major contributors to this motion is the deltoid muscle group and for this, an accurate modeling of the lines of action is indispensable. The aim of this work was to utilize a torus obstacle wrapping approach for the deltoids of an existing shoulder model and assess the feasibility of the approach during humeral abduction. The shoulder model from the AnyBody™ modeling system was used as a platform. The size of the tori is based on a magnetic resonance imaging (MRI) approach and several kinematic couplings are implemented to determine the trajectories of the tori during abduction. To assess the model behavior, the moment arms of the virtual muscle elements and the resultant glenohumeral joint reaction force (GHJF) were compared with reference data from the literature during abduction of the humerus in the range 20°-120°. The root mean square error for the anterior, lateral and posterior part between the simulated muscle elements and reference data from the literature was 3.9, 1.7 and 5.8 mm, respectively. The largest deviation occurred on the outer elements of the muscle groups, with 12.6, 10.4 and 20.5 mm, respectively. During abduction, there is no overlapping of the muscle elements and these are in continuous contact with the torus obstacles, thus enabling a continuous force transmission. This results in a rising trend of the resultant GHJF. The torus obstacle approach as a wrapping method for the deltoid muscles provides a guided muscle pathing by simultaneously approximating the curvature of the deltoid muscle. The results from the comparison of the simulated moment arms and the resultant GHJF are in accordance with those in the literature in the range 20°-120° of abduction. Although this study shows the strength of the torus obstacle as a wrapping approach, the method of fitting the tori according to MRI data was not suitable. A cadaver study is recommended to better validate and mathematically describe the torus approach.

Forty-eight new cases with infertility due to balanced chromosomal rearrangements: detailed molecular cytogenetic analysis of the 90 involved breakpoints.

A molecular cytogenetic study was performed on 48 infertile patients who were identified as carriers of balanced translocations (40 cases), inversions (6 cases) or insertions (2 cases) by means of banding cytogenetics. Cases with a Robertsonian translocation or pericentric inversion 2 or 9 were not included. In summary, 100 break-events occurred in these patients, and 90 different chromosomal regions were involved. Thus, this study confirmed the presence of abnormal karyotypes in a subgroup of patients seeking infertility treatment. Breaks were demonstrated to appear preferentially in GTG-light bands in these patients. Furthermore, the observed breakpoints were associated with genomic regions prone to instability due to the presence of segmental duplications. Nonetheless, further detailed molecular analysis will be necessary in the future to characterize the mechanisms and genetic basis for this phenomenon.

pH-dependence of complexion constants and complex mobility in capillary electrophoresis separations of dipeptide enantiomers.

The chiral separation of the LL- and DD-enantiomers of the dipeptides Ala-Tyr, Phe-Phe, and Asp-PheOMe has been investigated at pH 2.5 and pH 3.5 using beta-cyclodextrin (beta-CD), heptakis-(2,6-di-O-methyl)-beta-cyclodextrin, and heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin as chiral selectors. According to electrospray mass spectrometry, heptakis-(2,6-di-O-methyl)-beta-cyclodextrin was a mixture of six isomers. Reversal of the enantiomer migration order upon increasing the buffer pH from 2.5 to 3.5 was observed for all peptides with beta-cyclodextrin, for Ala-Tyr and Phe-Phe in the presence of heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin, and for Ala-Tyr using heptakis-(2,6-di-O-methyl)-beta-cyclodextrin. The migration behavior could be explained on the basis of the complexation constants and the mobilities of the peptide-cyclodextrin complexes. Both, the binding constants and complex mobilities decreased with increasing pH as the overall-charge of the peptides decreased. While the complexation constants primarily determined the migration order at pH 2.5, complex mobility dominated in most cases at pH 3.5.

Influence of the amino acid sequence and nature of the cyclodextrin on the separation of small peptide enantiomers by capillary electrophoresis using randomly substituted and single isomer sulfated and sulfonated cyclodextrins.

The separation of dipeptide and tripeptide enantiomers using negatively charged single isomers as well as randomly sulfated and sulfonated cyclodextrins (CDs) was investigated with respect to the amino acid sequence of the peptides and the nature of the CDs. Standardized conditions concerning buffer pH and molarity, CD concentration, and separation voltage were applied. Compared to suffobutylether-beta-CD and heptakis-(2,3-dimethyl-6-sulfato)-beta-CD, randomly sulfated beta-CD as well as the single isomer derivatives heptakis-6-sulfato-beta-CD and heptakis-(2,3-diacetyl-6-sulfato)-beta-CD were the more universal CDs for enantioseparations. The enantiomer migration order depended to a greater extent on the CD than on the amino acid sequence of the peptide although small structural differences such as formation of a peptide amide or ester affected the chiral recognition by the randomly substituted CD derivatives. Using sulfobutylether-beta-CD or heptakis-(2,3-diacetyl-6-sulfato)-beta-CD the DD enantiomers migrated before the LL enantiomers for most peptides while the opposite migration order, i.e. LL before DD, was observed when heptakis-6-sulfato-beta-CD was applied as chiral selector.

The significance of rudimentary nephrostomial tubules for the origin of the vertebrate gonad.

Initial gonadal development was studied in 30- to 40-day-old bovine embryos. The results were interpreted in conjunction with findings on pro- and mesonephric organization in larval forms of Ichthyophis kohtaoensis (Gymnophiona, Amphibia). In bovine embryos vestigial nephrostomial tubules are the immediate precursors of the blastemas for adrenocortical, rete, gonadal and Mullerian infundibular development. From the study of Ichthyophis it can be concluded that the vestigial nephrostomial tubules seen in the bovine embryo are pronephric and not mesonephric in nature. As a consequence, the indifferent mammalian gonad is defined as a modified homologue of the pronephros situated in the zone of pro-/mesonephric overlapping. Such an overlapping of the two kidney generations in the fully developed state is clearly seen in Ichthyophis. Overlapping of the mesonephros with the modified pronephros (gonad) is necessary to allow intercalation of mesonephric tubules (efferent ductules in mammals) into the male seminal excurrent duct system.

On the origin and prenatal development of the bovine adrenal gland.

Decisive steps of bovine prenatal adrenal development were investigated in 46 embryos and fetuses using histological, electron microscopical, immuno-, enzyme and lectin histochemical methods. About day 30, the intermediate mesoderm between the cranial mesonephros and coelomic cavity is segmentally organized. It consists of proliferating tissue complexes that are connected to the coelomic cavity by vestigial nephrostomial tubules. This segmental organization soon disappears, however, due to longitudinal fusion of the tissue complexes into a continuous joined blastema. This blastema of intermediate mesodermal (nephric) origin becomes positive for alkaline phosphatase at about 30 days, and slightly later also for acetylcholinesterase. The most cranial portions of this common blastema represent the adrenocortical anlage, the following portions the gonadal rete blastema. A reevaluation of the comparative anatomical record revealed that a nephric origin of adrenocortical or interrenal cells is a general feature of all vertebrates and that the erroneous assumption of the lateral plate-derived coelothelium as precursor of the adrenocortical (interrenal) blastema should be definitively abandoned. The first adrenomedullary precursor cells become visible in the bovine adrenal primordium at day 35. At 50 days, both components (medullary and cortical precursors) are present as interpenetrating plates and strands between large sinusoid vessels and exhibit a strong MIB-1 activity, indicative of a high proliferation rate. About day 60 the cellular proliferation slows down in some of the adrenocortical precursor cells, and the separation into a visible cortex and medulla is initiated. From about day 80 on, the medullary tissue coalesces into a large, continuous area in the interior of the gland, surrounded by a narrow cortical glomerulo-fasciculata that becomes positive for 3beta-hydroxysteroid dehydrogenase at about day 90. Autonomous nerves penetrate the blastemal region as early as day 31. When the separation into cortex and medulla starts, the nerves are more concentrated in the latter. From 130 days on, nerve fascicles reach the interior of the organ not only from its medial side, but also from the capsule surrounding the gland. The penetrating bundles traverse the zona glomerulo-fasciculata without ramification and split off at the border to the medulla. Here, in the outer zone of the medulla, they constitute a particularly dense plexus, whereas in the central medulla a less dense innervation is observed. Up until 90 days, cells with the characteristic features of primordial germ cells are present within the confines of the adrenal gland.

Identification and temporospatial distribution of bovine primordial germ cells prior to gonadal sexual differentiation.

The temporospatial distribution of bovine primordial germ cells was studied in 34 embryos (18 to 39 days). For a reliable identification of bovine primordial germ cells in varying localizations and at different developmental stages the alkaline phosphatase reaction combined with the use of selected lectins was applied. The first potential primordial germ cells were identified in an 18-day-old trilaminar embryo in the caudal wall of the proximal yolk sac at a distance of less than 100 microm from the germ disc. These cells are alkaline phosphatase-positive. but do not yet react with lectins. From 18 through 23 days, morphogenetic folding converts the flat trilaminar disc into a cylindrical embryonic body. During this folding process primordial germ cells located in the proximal yolk sac area are incorporated into the embryo when this portion of the yolk sac becomes the hind- and mid-gut. Consequently, in 23- to 25-day-old embryos putative primordial germ cells (alkaline phosphatase- and lectin-positive) are situated predominantly in the axial body region at the level of the mesonephros. When the gonadal ridge develops in this region (about day 27) it contains a certain number of primordial germ cells present from the very beginning. Thus, the assumptions of a long-range chemoattraction of primordial germ cells by the gonadal ridge, of active immigration from an extraembryonic site. or of a passive transportation via the blood stream are not necessary to explain the initial settlement of bovine primordial germ cells in the gonadal ridge. Within the gonadal ridge (days 27-31) and later in the still sexually indifferent gonadal fold (32-39 days) the primordial germ cells are unevenly distributed. Extragonadal potential primordial germ cells (alkaline phosphatase-positive, but with reduced or no lectin staining) are regularly present in large numbers in bovine embryos with indifferent gonads. Such cells occur predominantly in the paraaortal tissue and in the liver, but also in the branchial arches. The different locations of extragonadal primordial germ cells are discussed in the light of recent evidence that germ cells and haematopoietic cells share common ancestors.

Characterization of a thermosensitive mutant of Streptomyces hygroscopicus defective in both DNA and RNA syntheses.

A stable temperature sensitive mutant of Streptomyces hygroscopicus JA6599 defective in both DNA and RNA syntheses is described. The mutant ts35 is characterized by an immediate stop of DNA synthesis and continued protein synthesis after transfer to restrictive temperature. The reinitiation of DNA synthesis begins immediately after a return to the permissive temperature. This kinetics of macromolecular synthesis at restrictive temperature appears to share similarities with a defect in the DNA elongation process, as described for Escherichia coli (Carl 1970, Hanna and Carl 1975). The simultaneous stop of both DNA and RNA syntheses may be caused by an additional mutational event affecting also the RNA synthesis. The data were discussed with respect to similar results in E. coli.

Interaction of bacteriophage O2 with strains of the genus Oerskovia.

Bacteriophage O2 multiplies normally on Oerskovia turbata IMET 47 153. It has a burst size of about 100 p.f.u. per infected cell and a latent period of 100 min at 30 degrees C. On Oerskovia xanthineolytica IMET 47 383 clear spots were formed after addition of high phage concentrations onto agar top layers. By phase contrast observation, and measurement of the optical density of infected cultures, it was found that the clearing effect on strain IMET 47 383 was due to lysis-from-without. Phage O2 adsorbs and injects its DNA into cells of strain IMET 47 383 but phage multiplication does not occur, and the phage DNA becomes degraded. Inhibition of phage DNA injection by the combined action of xanthotoxin -- u.v. irradiation abolished the clearing activity of phage lysates. Therefore, both adsorption and DNA injection seem to be prerequisites for the release of a lytic activity out of the phage particle, which is responsible for the clearing effect on strain IMET 47 383.

Transduction in Streptomyces hygroscopicus mediated by the temperate bacteriophage SH10.

The temperate actinophage SH10 mediates generalized transduction in Streptomyces hygroscopicus at low frequency. The efficiency of transduction depends on the average phage input, age of outgrowing spores of the recipient and on the selective marker. The highest EOT was found for the auxotrophic mutants 21(phe-) and 5(try-) (4.2 x 10(-6) and 2.7 x 10(-6), respectively). Transduction of the thermosensitive mutant NG14-216 ts 35 was two orders of magnitude lower (2.5 x 10(-8)). The transductant colonies segregated into stable and unstable clones. Stable transductants were never found to be lysogenic for phage SH10.

Characterization of the virulent actinophage S2.

The virulent actinophage S2 isolated from soil infects Streptomyces hygroscopicus 6599, S. lividans 66, and S. levoris 1331. Morphology of S2 was studied by electron microscopy. Influence of growth medium and temperature on multiplication of S2 has been studied qualitatively. S2 is more sensitive to UV irradiation on strain 66 than on 1331. In contrast to UV, hydroxylamine mutagenesis delivered 9 stable ts mutants which belong to 3 complementation groups. Most of the ts mutations isolated on 1331 were found to be host dependent, 8 of 9 mutants were found to be able to grow at 40 degrees C on strain 66 but none of them on 1331. Moreover 2 of the mutants were found to be much more heat sensitive in 6599 than in 1331, as indicated by the changes in half-life temperatures. The latent period of S2+ depends on temperature and germination state of the spores. Under optimal conditions we found 140 min. Ts2 and ts7 have been classified as a late and ts17 as an early mutant.