Effect of joint rotation correction when measuring elongation of the gastrocnemius medialis tendon and aponeurosis

It is well known that during maximal plantar flexion contractions the ankle joint rotation overestimates the actual elongation of the tendon and aponeurosis. The aim of this study was to examine the influence of the curve length changes of the Achilles tendon on the joint rotation corrected elongation and strain of the gastrocnemius medialis (GM) tendon and aponeurosis. Nine subjects (age: 29.4 ± 5.7 years, body mass: 78.8 ± 6.8 kg, body height: 178 ± 4 cm) participated in the study. The subjects performed maximal voluntary isometric plantarflexion contractions in the prone position on a Biodex-dynamometer. Ultrasonography (Aloka SSD 4000) was used to visualize the muscle belly of the GM muscle-tendon unit. To calculate the curve length changes of the Achilles tendon its surface contour was reconstructed using a series of small reflective skin markers having a diameter of 2.5 mm. The elongation of the GM tendon and aponeurosis was calculated (a) as the difference of the measured and the passive (due to joint rotation) displacement of the tendon and aponeurosis and (b) as the difference of the measured displacement and the length changes of the reconstructed Achilles tendon surface contour. The absolute difference between the elongation obtained by both methods were 1.2 ± 0.4 mm. These differences were due to the higher changes in length obtained by the reconstruction of the tendon curved surface contour as compared to the changes observed in the passive displacement of the digitised point at the aponeurosis. Without correcting for angle joint rotation, the measured elongation clearly overestimates the actual elongation of the GM tendon and aponeurosis. After the passive displacement correction the calculated elongation still overestimates the actual elongation of the GM tendon and aponeurosis. However, this overestimation has a negligible effect on the examined in vivo strain (0.3%) of the tendon and aponeurosis.     

DNA damage and nitric oxide synthesis in experimentally infected Balb/c mice with Trypanosoma cruzi

This study aimed to evaluate whether experimental Chagas disease in acute phase under benznidazole therapy can cause DNA damage in peripheral blood, liver, heart, and spleen cells or induce nitric oxide synthesis in spleen cells. Twenty Balb/c mice were distributed into four groups: control (non-infected animals); Trypanosoma cruzi infected; T. cruzi infected and submitted to benznidazole therapy; and only treated with benznidazole. The results obtained with the single cell gel (comet) assay showed that T. cruzi was able induce DNA damage in heart cells of both benznidazole treated or untreated infected mice. Similarly, T. cruzi infected animals showed an increase of DNA lesions in spleen cells. Regarding nitric oxide synthesis, statistically significant differences (p<0.05) were observed in all experimental groups compared to negative control, the strongest effect observed in the T. cruzi infected group. Taken together, these results indicate that T. cruzi may increase the level of DNA damage in mice heart and spleen cells. Probably, nitric oxide plays an important role in DNA damaging whereas benznidazole was able to minimize induced T. cruzi genotoxic effects in spleen cells.     

Effect of treating induced mitochondrial damage on embryonic development and epigenesis

Germinal vesicle transplantation (GVT) has been proposed as a possible treatment to correct age-related oocyte aneuploidy caused by dysfunctional ooplasm. How healthy ooplasm regulates normal meiosis and subsequent development has yet to be elucidated, but impaired mitochondrial metabolism may be attributable to incomplete segregation of the oocyte chromosomes. In the present study, after ooplasmic mitochondrial damage by photoirradiating chloromethyl-X-rosamine, examination of the oocyte nuclei's ability to survive after transfer into healthy ooplasts was performed. To assess their fertilizability and potential for development, GVT oocytes were fertilized by intracytoplasmic sperm injection (ICSI) and transferred to foster mice. Condition of the offspring at birth was assessed, and epigenetic analysis was performed. Photosensitization consistently inhibited oocyte maturation. However, after GVT of photosensitized nuclei into healthy ooplasts, 67.2% were reconstituted, and 76.2% of these matured normally, with an overall rate of 51.2%, much higher than that (6.0%) in the mitochondrially injured oocytes. After ICSI, 65.8% (52/79) of GVT oocytes were fertilized normally, and 21.1% (11/52) eventually reached the blastocyst stage. The transfer of 132 two-cell GVT embryos into the oviducts of pseudopregnant females resulted in 17 apparently healthy live offspring. For some key developmental genes, a high level of expression was identified in the GVT and "rescue"-derived fetal adnexa. Thus, one can induce in oocyte mitochondria a photosensitization-based type of damage, which consistently inhibits GV breakdown, meiotic spindle formation, chromosomal segregation, and polar body extrusion. Germinal vesicle transplanted and rescued oocytes were able to undergo maturation, fertilization, and embryonic cleavage and, ultimately, to develop to term. This approach may provide a model with which to study the age-related ooplasmic dysfunction seen in human oocytes.     

The interplay of osteogenesis and hematopoiesis: expression of a constitutively active PTH/PTHrP receptor in osteogenic cells perturbs the establishment of hematopoiesis in bone and of skeletal stem cells in the bone marrow

The ontogeny of bone marrow and its stromal compartment, which is generated from skeletal stem/progenitor cells, was investigated in vivo and ex vivo in mice expressing constitutively active parathyroid hormone/parathyroid hormone-related peptide receptor (PTH/PTHrP; caPPR) under the control of the 2.3-kb bone-specific mouse Col1A1 promoter/enhancer. The transgene promoted increased bone formation within prospective marrow space, but delayed the transition from bone to bone marrow during growth, the formation of marrow cavities, and the appearance of stromal cell types such as marrow adipocytes and cells supporting hematopoiesis. This phenotype resolved spontaneously over time, leading to the establishment of marrow containing a greatly reduced number of clonogenic stromal cells. Proliferative osteoprogenitors, but not multipotent skeletal stem cells (mesenchymal stem cells), capable of generating a complete heterotopic bone organ upon in vivo transplantation were assayable in the bone marrow of caPPR mice. Thus, PTH/PTHrP signaling is a major regulator of the ontogeny of the bone marrow and its stromal tissue, and of the skeletal stem cell compartment.     

Further cytogenetical studies on diploid and polyploid species of Eryngium L. (Saniculoideae, Apiaceae) from Argentina

Meiotic studies are carried out in 7 species of Eryngium L. (Saniculoideae, Apiaceae), belonging to both sections Foetida and Panniculata. The chromosome number of E. dorae Norm. (n=8) (Foetida) is reported for the first time, while the gametic chromosome number of E. nudicaule Lam. (n=7) (Foetida) and E. eburneum Decne. (n=8), E. horridum Malme (n=8), E. megapotamicum Malme (n=16), E. mesopotamicum Pedersen (n=24), and E. pandanifolium Cham. et Schlechtd. (n=24) (all belonging to Panniculata) is confirmed in several natural populations. Whereas in section Foetida all species are diploids and two basic chromosome numbers are present (x=8 and x=7), in section Panniculata all species are x=8 but there are three different ploidy levels (diploid, tetraploid, hexaploid). This study reveals that meiosis in all species is normal, with regular bivalent formation in all studied cells. Furthermore, the pollen stainability is above 80% in all cases. These data, together with the previous karyotype analyses, will contribute to the clarification of the relationships between members of both sections, where different mechanisms of speciation have been postulated.     

A metallo-beta-lactamase enzyme in action: crystal structures of the monozinc carbapenemase CphA and its complex with biapenem

One strategy developed by bacteria to resist the action of beta-lactam antibiotics is the expression of metallo-beta-lactamases. CphA from Aeromonas hydrophila is a member of a clinically important subclass of metallo-beta-lactamases that have only one zinc ion in their active site and for which no structure is available. The crystal structures of wild-type CphA and its N220G mutant show the structural features of the active site of this enzyme, which is modeled specifically for carbapenem hydrolysis. The structure of CphA after reaction with a carbapenem substrate, biapenem, reveals that the enzyme traps a reaction intermediate in the active site. These three X-ray structures have allowed us to propose how the enzyme recognizes carbapenems and suggest a mechanistic pathway for hydrolysis of the beta-lactam. This will be relevant for the design of metallo-beta-lactamase inhibitors as well as of antibiotics that escape their hydrolytic activity.     

Differences between measured and resultant joint moments during isometric contractions at the ankle joint

The purpose of this study was to examine two hypotheses: (a) during voluntary and electrically induced isometric contractions the moments measured at the dynamometer are different from the resultant moments in the same plane around the ankle joint and (b) at a given resultant moment during electrically induced isometric contractions the ankle angle while loading is different from the ankle angle while unloading. Twenty-seven long distance runners participated in the study. All subjects performed isometric maximal voluntary contractions (MVC) and contractions induced by electrostimulation at four different ankle-knee angle combinations on a Biodex-dynamometer. The kinematics of the leg were recorded using the vicon 624 system with eight cameras operating at 120 Hz. The main findings were: (a) the resultant moment at the ankle joint and the moment measured by the Biodex-dynamometer during isometric contractions are different, (b) during a plantar flexion effort the ankle angle changes significantly, whereas the knee angle shows only small and in most cases not significant changes, and (c) at identical resultant ankle joint moments the ankle angles are different between the loading and the unloading phases. The observed differences may lead to erroneous conclusions concerning the following: (a) diagnostic of muscle architecture, (b) estimation of the moment-ankle angle relationship and (c) estimation of the strain and hysteresis of tendons and aponeuroses.     

Determination of amphetamine-derived designer drugs in human urine by SPE extraction and capillary electrophoresis with mass spectrometry detection

In recent years, a number of newer designer drugs have entered the illicit drug market. The methylenedioxy-derivates of amphetamine represent the largest group of designer drugs. This paper describes a method for screening for and quantification of ten 2,5-methylenedioxy-derivates of amphetamine and phenylethylamine in human urine, using capillary electrophoresis coupled to electrospray ionisation-mass spectrometry (CE-ESI-MS). Prior to CE-MS analysis, a simple solid-phase extraction (SPE) was used for sample cleanup. The method was validates according to international guidelines.