Characterization of muscle architecture in children and adults using magnetic resonance elastography and ultrasound techniques

The purpose of this study is to characterize the muscle architecture of children and adults using magnetic resonance elastography and ultrasound techniques. Five children (8-12 yr) and seven adults (24-58 yr) underwent both tests on the vastus medialis muscle at relaxed and contracted (10% and 20% of MVC) states. Longitudinal ultrasonic images were performed in the same area as the phase image showing the shear wave's propagation. Two geometrical parameters were defined: the wave angle (α(_MRE)) corresponding to the shear wave propagation and the fascicule angle (α(_US)) tracking the path of fascicles. Moreover, shear modulus was measured at different localizations within the muscle and in the subcutaneous adipose tissue. The association of both techniques demonstrates that the shear wave propagation follows the muscle fascicles path, reflecting the internal muscle architecture. At rest, ultrasound images revealed waves propagating parallel to the children fascicle while adults showed oblique waves corresponding to already oriented (α(_US)=15.4±2.54°) muscle fascicles. In contraction, the waves' propagation were in an oblique direction for children (α(_US_10%MVC)=10.6±2.27°, α(_US_20%MVC)=10.2±2.29°) as well as adults (α(_US_10%MVC)=15.4±2.54°, α(_US_20%MVC)=17.2±2.44°). A stiffness variation (1 kPa) was found between the upper and lower parts of the adult VM muscle and a lower stiffness (1.85±0.17 kPa) was measured in the subcutaneous adipose tissue. This study demonstrates the feasibility of the MRE technique to provide geometrical insights from the children and adults muscles and to characterize different physiological media.     

In vivo DNA gene electro-transfer: a systematic analysis of different electrical parameters

BACKGROUND: Intramuscular plasmid injection followed by electroporation is an efficient method for gene therapy or vaccination. Several protocols have been described that give good transduction levels with several reporter genes. METHODS: In this work we have explored the efficiency of gene delivery upon variation of the different electrical parameters such as pulse length frequency and voltage monitoring both on short- and long-term protein production. RESULTS: Having defined the best performing parameters, we have designed a short electric treatment that gives good levels of plasmid-encoded protein in different species such as mice, rabbits and monkeys.     

Albofungin formation by a strain isolated as a result of fusion of protoplasts of organisms producing aminoglycoside antibiotics

Strain 344 synthesizing an antibiotic complex was isolated after fusion of the protoplasts of Streptomyces monomycini producing monomycin and Streptomyces kanamyceticus producing kanamycin. The major component of the complex was identified with albofungin and the minor one was suggested to be chloralbofungin. In the cultures of strain 344 variants forming monomycin were detected. After regeneration of the protoplasts of the parent strains there were isolated no stable clones synthesizing antibiotics differing from monomycin and kanamycin.     

Thermotoga maritima-Escherichia coli chimeric topoisomerases. Answers about involvement of the carboxyl-terminal domain in DNA topoisomerase I-mediated catalysis

Bacterial topoisomerases I are generally composed of two domains as follows: a core domain, which contains all the conserved motifs involved in the trans-esterification reactions, and a carboxyl-terminal domain, highly variable in size and sequence. In the present work, we have addressed the question of the respective roles of the two domains in the different steps of the topoisomerization cycle. For this purpose, we prepared various recombinant topoisomerases from two model enzymes: topoisomerase I from the hyperthermophilic bacterium Thermotoga maritima and topoisomerase I from Escherichia coli. We compared the properties of the two core domains to that of the topoisomerases formed by combining the core domain of one enzyme to the carboxyl-terminal domain of the other. We found that, contrary to E. coli (Lima, C. D., Wang, J. C., and Mondragon, A. (1993) J. Mol. Biol. 232, 1213-1216), the core domain from T. maritima (TmTop65) is able to sustain by itself a complete topoisomerization cycle, although with low efficiency. Fusion of TmTop65 to the entire carboxyl-terminal domain from E. coli considerably increases binding efficiency, thermal stability, and DNA relaxation activity. Moreover, the chimera predominantly acquires the cleavage specificity of E. coli full-length topoisomerase. For the chimera obtained by fusion of the T. maritima carboxyl-terminal domain to the core EcTop67, very low DNA relaxation activity and binding are recovered, but formation of a covalent DNA adduct is impaired. Taken together, our results show that the presence and the nature of the carboxyl-terminal domain of bacterial topoisomerases I strongly determine their DNA binding efficiency and cleavage specificity but is not strictly required for strand passage.     

Functional,radiological and biological markers of alveolitis and infections of the lower respiratory tract in patients with systemic sclerosis

Background

A progressive lung disease and a worse survival have been observed in patients with systemic sclerosis and alveolitis. The objective of this study was to define the functional, radiological and biological markers of alveolitis in SSc patients.

Methods

100 SSc patients (76 with limited and 24 with diffuse disease) underwent a multistep assessment of cardiopulmonary system: pulmonary function tests (PFTs) every 6–12 months, echocardiography, high resolution computed tomography (HRCT) and bronchoalveolar lavage (BAL), if clinically advisable. Alveolar and interstitial scores on HRCT and IL-6 plasma levels were also assessed as lung disease activity indices.

Results

90 SSc patients with abnormal PFTs and 3 with signs and/or symptoms of lung involvement and normal PFTs underwent HRCT and echocardiography. HRCT revealed evidence of fibrosis in 87 (93.5%) patients, with 55 (59.1%) showing both ground glass attenuation and fibrosis. In 42 patients who had exhibited ground glass on HRCT and consented to undergo BAL, 16 (38.1%) revealed alveolitis. 12 (75%) of these patients had restrictive lung disease (p < 0.0001) and presented diffuse skin involvement (p = 0.0009). IL-6 plasma levels were higher in patients with alveolitis than in patients without (p = 0.041). On logistic regression model the best independent predictors of alveolitis were diffuse skin involvement (OR(95%CIs):12.80(2.54–64.37)) and skin score > 14 (OR(95%CIs):7.03(1.40–34.33)). The alveolar score showed a significant correlation with IL-6 plasma levels (r = 0.36, p = 0.001) and with the skin score (r = 0.33, p = 0.001). Cultures of BAL fluid resulted positive in 10 (23.8%) of the 42 patients that underwent BAL and after one year a deterioration in PFTs occurred in 8 (80%) of these patients (p = 0.01). Pulmonary artery systolic pressure ≥ 40 mmHg was found in 6 (37.5%) patients with alveolitis.

Conclusion

We found alveolitis only in 38.1% of the patients who had exhibited ground glass on HRCT and then underwent BAL, probably because the concomitant fibrosis influenced results. A diffuse skin involvement and a restrictive pattern on PFTs together with ground glass on HRCT were judged possible markers of alveolitis, a BAL examination being indicated as the next step. Nevertheless BAL would be necessary to detect any infections of the lower respiratory tract that may cause further deterioration in lung function.     

Some reproductive traits of the Tristan klipfish, Bovichtus diacanthus (Carmichael 1819) (Notothenioidei: Bovichtidae) from Tristan da Cunha (South Atlantic)

The reproductive biology of the Tristan klipfish, Bovichtus diacanthus, was investigated by macroscopic and histological analyses of the gonads. Fish samples were collected in tide pools at Tristan da Cunha in July 2004. Most specimens of both sexes were developing, or sexually mature, with a gonadosomatic index (GSI) of 7.0–9.2% in females and 0.2–0.6% in males. Histologically, testes showed a random distribution of spermatogonia along the lobules, a condition defined as the unrestricted spermatogonial type. Ripe males exhibited lobules with all spermatogenic stages of development from spermatogonia to spermatozoa. In mature females, the ovarian follicles consisted of three main cohorts of oocytes of different sizes; the smaller one represented by previtellogenic oocytes of 15–150 μm and the other two by yolked oocytes measuring, respectively, 300–1000 and 800–1500 μm. The overlap between the stock of advanced yolked oocytes and the early yolked oocytes was low, decreasing progressively with final maturation. As a result, B. diacanthus was considered a batch spawner, with a spawning season extending from July to August onward. Batch fecundity, based on the most advanced yolked oocytes, was 2,047–8,317 mature oocytes/female, whereas the relative fecundity was 77–141 mature oocytes/g. In the light of the phyletically basal position of bovichtids in the suborder, the reproductive traits of B. diacanthus were compared with those previously described in other Antarctic and non-Antarctic notothenioids.     

6-aryl-2,4-dioxo-5-hexenoic acids, novel integrase inhibitors active against HIV-1 multiplication in cell-based assays

A series of 6-aryl-2,4-dioxo-5-hexenoic acids, were synthesized and tested against HIV-1 in cell-based assays and against recombinant HIV-1 integrase (rIN) in enzyme assays. Compound 8a showed potent antiretroviral activity (EC(50)=1.5 microM) and significant inhibition against rIN (strand transfer: IC(50)=7.9 microM; 3'-processing: IC(50)=7.0 microM). A preliminary molecular modeling study was carried out to compare the spatial conformation of 8a with those of L-731988 (4) and 5CITEP (7) in the IN core.     

Translation initiation factor IF2 interacts with the 30 S ribosomal subunit via two separate binding sites

The functional properties of the two natural forms of Escherichia coli translation initiation factor IF2 (IF2alpha and IF2beta) and of an N-terminal deletion mutant of the factor (IF2DeltaN) lacking the first 294 residues, corresponding to the entire N-terminal domain, were analysed comparatively. The results revealed that IF2alpha and IF2beta display almost indistinguishable properties, whereas IF2DeltaN, although fully active in all steps of the translation initiation pathway, displays functional activities having properties and requirements distinctly different from those of the intact molecule. Indeed, binding of IF2DeltaN to the 30 S subunit, IF2DeltaN-dependent stimulation of fMet-tRNA binding to the ribosome and of initiation dipeptide formation strongly depend upon the presence of IF1 and GTP, unlike with IF2alpha and IF2beta. The present results indicate that, using two separate active sites, IF2 establishes two interactions with the 30 S ribosomal subunit which have different properties and functions. The first site, located in the N domain of IF2, is responsible for a high-affinity interaction which "anchors" the factor to the subunit while the second site, mainly located in the beta-barrel module homologous to domain II of EF-G and EF-Tu, is responsible for the functional ("core") interaction of IF2 leading to the decoding of fMet-tRNA in the 30 S subunit P-site. The first interaction is functionally dispensable, sensitive to ionic-strength variations and essentially insensitive to the nature of the guanosine nucleotide ligand and to the presence of IF1, unlike the second interaction which strongly depends upon the presence of IF1 and GTP.     

Mouse SYCP2 is required for synaptonemal complex assembly and chromosomal synapsis during male meiosis

During meiosis, the arrangement of homologous chromosomes is tightly regulated by the synaptonemal complex (SC). Each SC consists of two axial/lateral elements (AEs/LEs), and numerous transverse filaments. SC protein 2 (SYCP2) and SYCP3 are integral components of AEs/LEs in mammals. We find that SYCP2 forms heterodimers with SYCP3 both in vitro and in vivo. An evolutionarily conserved coiled coil domain in SYCP2 is required for binding to SYCP3. We generated a mutant Sycp2 allele in mice that lacks the coiled coil domain. The fertility of homozygous Sycp2 mutant mice is sexually dimorphic; males are sterile because of a block in meiosis, whereas females are subfertile with sharply reduced litter size. Sycp2 mutant spermatocytes exhibit failure in the formation of AEs and chromosomal synapsis. Strikingly, the mutant SYCP2 protein localizes to axial chromosomal cores in both spermatocytes and fetal oocytes, but SYCP3 does not, demonstrating that SYCP2 is a primary determinant of AEs/LEs and, thus, is required for the incorporation of SYCP3 into SCs.