Synthesis of new 9-glycosyl-4,9-dihydropyrano [3,4-b]indole-1(3H)-ones as antibacterial agents

A series of new 9-glycosyl-4,9-dihydropyrano[3,4-b]indole-1(3H)-ones 3 was synthesized in moderate to low yields. 4,9-Dihydropyrano[3,4-b]indole-1(3H)-ones (1) were coupled with different acetobromoglycopyranoses 2 in refluxing toluene in the presence of silver oxide to afford one coupling product of the respective N-glycosides. α-L-Arabinopyranosides 3j and 3m were the most active glycosides among the tested compounds against certain Gram positive and Gram negative bacterial strains.     

Isolation and Characterization of Moderately Halophilic Bacteria from Tunisian Solar Saltern

Bacterial screenings from solar saltern in Sfax (Tunisia) lead to the isolation of 40 moderately halophilic bacteria which were able to grow optimally in media with 5–15% of salt. These isolates were phylogenetically characterized using 16S rRNA gene sequencing. Two groups were identified including 36 strains of Gamma-Proteobacteria (90%) and 4 strains of Firmicutes (10%). The Gamma-Proteobacteria group consisted of several subgroups of the Halomonadaceae (52.5%), the Vibrionaceae (15%), the Alteromonadaceae (10%), the Idiomarinaceae (7.5%), and the Alcanivoracaceae (5%). Moreover, three novel species: 183ZD08, 191ZA02, and 191ZA09 were found, show <97% sequence similarity of the 16S rRNA sequences while compared to previously published cultivated species. Most of these strains (70%) were able to produce hydrolases: amylases, proteases, phosphatases, and DNAases. Over the isolates, 60% produced phosphatases, 15.0% proteases, 12.5% amylases and DNAases equally. This study showed that the solar saltern of Sfax is an optimal environment for halophilic bacterial growth, where diverse viable bacterial communities are available and may have many industrial applications.     

Three-dimensional mechanical properties of porcine coronary arteries: a validated two-layer model

The normal coronary artery consists of two mechanically distinct layers: intima-media and adventitia. The objective of this study is to establish a two-layer three-dimensional (3-D) stress-strain relation of porcine coronary arteries. Experimental measurements were made by a series of biaxial tests (inflation and axial extension) of intact coronary arteries and, subsequently, their corresponding intima-media or adventitia layer. The Fung-type exponential strain energy function was used to describe the 3-D strain-stress relation for each layer and the intact wall. A genetic algorithm was used to determine the material constants in the Fung-type constitutive equation by curve fitting the experimental data. Because one layer must be sacrificed before the other layer can be tested, the material property of the missing layer was computed from the material constants of the intact vessel and the tested layer. A total of 20 porcine hearts were used: one group of 10 hearts for the left anterior descending artery and another group of 10 hearts for the right coronary artery. Each group was further divided into two subgroups of five specimens tested for the intact wall and the intima-media layer and for the intact wall and the adventitia layer. Our results show statistically significant differences in the material properties of the two layers. The mathematical model was validated by experimental stress-strain data for individual layers. The validated 3-D constitutive model will serve as a foundation for formulation of layer-specific boundary value problems in coronary physiology and cardiology.     

Nonuniformity of axial and circumferential remodeling of large coronary veins in response to ligation

The pressure-induced remodeling of coronary veins is important in coronary venous retroperfusion. Our hypothesis is that the response of the large coronary veins to pressure overload will depend on the degree of myocardial support. Eleven normal Yorkshire swine from either sex, weighing 31-39 kg, were studied. Five pigs underwent ligation of the left anterior descending (LAD) vein, and six served as sham-operated controls. The ligation of the coronary vein caused an increase in pressure intermediate to arterial and venous values. After 2 wk of ligation, the animals were euthanized and the coronary vessels were perfusion-fixed with glutaraldehyde. The LAD vein was sectioned, and detailed morphometric measurements were made along its length from the point of ligation near the base down to the apex of the heart. The structural remodeling of the vein was circumferentially nonuniform because the vein is partially embedded in the myocardium; it was also axially nonuniform because it is tethered to the myocardium to different degrees along its axial length. The wall area was significantly larger in the experimental group, whereas luminal area in the proximal LAD vein was significantly smaller in the same group compared with sham-operated controls. The wall thickness-to-radius ratio was also significantly larger in the experimental group in proportion to the increase in pressure. The major conclusion of this study is that the response of the vein depends on the local wall stress, which is, in part, determined by the surrounding tissue. Furthermore, the geometric remodeling of the coronary vein restores the circumferential stress to the homeostatic value.     

Axial nonuniformity of geometric and mechanical properties of mouse aorta is increased during postnatal growth

The hemodynamic conditions of aorta are relatively uniform prenatally and become more heterogeneous postnatally. Our objective was to quantify the heterogeneity of geometry and mechanical properties during growth and development. To accomplish this objective, we obtained a systematic set of data on the geometry and mechanical properties along the length of mouse aorta during postnatal development. C57BL/6 mice of ages 1-33 days were studied. The ascending aorta was cannulated in situ and preconditioned with several cyclic changes in pressure. We investigated the axial variations of geometry (diameter and length) and mechanical properties (stress-stain relation, elastic modulus and compliance) of the mouse aorta from the aortic valve to the common iliac. Our results show that the arterial blood pressure of mice increased from approximately 30 to 80 mmHg during the first 2 wk of life. The stretch ratio, diameter, wall (intima-media) thickness, and total lumen volume of mouse aorta increased with age. The aorta was transformed from a cylindrical tube at birth to a tapered structure during growth. Furthermore, we found the mechanical properties were fairly uniform along the length of the aorta at birth and become more nonuniform with age. We conclude that the rapid change of blood pressure and blood flow after birth alter the geometric and mechanical properties differentially along the length of the aorta. Hence, the axial nonuniformity of the aorta increases as the organ becomes more specialized during growth and development.     

Sinorhizobium americanum symbiovar mediterranense is a predominant symbiont that nodulates and fixes nitrogen with common bean (Phaseolus vulgaris L.) in a Northern Tunisian field

A total of 40 symbiotic bacterial strains isolated from root nodules of common bean grown in a soil located in the north of Tunisia were characterized by PCR-RFLP of the 16S rRNA genes. Six different ribotypes were revealed. Nine representative isolates were submitted to phylogenetic analyses of rrs, recA, atpD, dnaK, nifH and nodA genes. The strains 23C40 and 23C95 representing the most abundant ribotype were closely related to Sinorhizobium americanum CFNEI 156(T). S. americanum was isolated from Acacia spp. in Mexico, but this is the first time that this species is reported among natural populations of rhizobia nodulating common bean. These isolates nodulated and fixed nitrogen with this crop and harbored the symbiotic genes of the symbiovar mediterranense. The strains 23C2 and 23C55 were close to Rhizobium gallicum R602sp(T) but formed a well separated clade and may probably constitute a new species. The sequence similarities with R. gallicum type strain were 98.7% (rrs), 96.6% (recA), 95.8% (atpD) and 93.4% (dnaK). The remaining isolates were, respectively, affiliated to R. gallicum, E. meliloti, Rhizobium giardinii and Rhizobium radiobacter. However, some of them failed to re-nodulate their original host but promoted root growth.     

Which diameter and angle rule provides optimal flow patterns in a coronary bifurcation?

The branching angle and diameter ratio in epicardial coronary artery bifurcations are two important determinants of atherogenesis. Murray's cubed diameter law and bifurcation angle have been assumed to yield optimal flows through a bifurcation. In contrast, we have recently shown a 7/3 diameter law (HK diameter model), based on minimum energy hypothesis in an entire tree structure. Here, we derive a bifurcation angle rule corresponding to the HK diameter model and critically evaluate the streamline flow through HK and Murray-type bifurcations. The bifurcations from coronary casts were found to obey the HK diameter model and angle rule much more than Murray's model. A finite element model was used to investigate flow patterns for coronary artery bifurcations of various types. The inlet velocity and pressure boundary conditions were measured by ComboWire. Y-bifurcation of Murray type decreased wall shear stress-WSS (10%-40%) and created an increased oscillatory shear index-OSI in atherosclerosis-prone regions as compared with HK-type bifurcations. The HK-type bifurcations were found to have more optimal flow patterns (i.e., higher WSS and lower OSI) than Murray-type bifurcations which have been traditionally believed to be optimized. This study has implications for changes in bifurcation angles and diameters in percutaneous coronary intervention.     

Use of Taguchi's methods as a basis to optimize hybridoma cell line growth and antibody production in a spinner flask

Taguchi’s methods were used for the design of an experimental strategy aimed at optimizing cell density and monoclonal antibody (mAb) production from a spinner flask hybridoma culture. 23G11 is an antibody to the human leukocyte adhesion molecule, CR3 or β 2 integrin (CD11b/CD18). It recognizes specifically the A-domain of the α subunit CD11b. Anti β 2 integrin monoclonal antibodies hold a great potential for preventing inflammation mediated tissue injuries. An L8 orthogonal experimental design was used to investigate four different culture components: stirring speed, nature of serum, concentration of serum and nature of media (RPMI 1640 or RPMI 1640 supplemented with glucose and glutamine). The experiments were conducted using two levels for each factor studied and a direct ELISA test was used to estimate the level of antibody production. Statistical analysis of the collected data pointed to the stirring speed and serum concentration, and the interaction between these parameters, as the components that affected cell growth. Antibody production was affected by these factors and by the nature of medium but also by the following two interactions: stirring speed/nature of serum and stirring speed/concentration of serum. This study emphasizes the value of using Taguchi’s methods as a basis for optimization of mAb production from a hybridoma culture, in cost effective and significantly less labor intensive ways. This revised version was published online in August 2006 with corrections to the Cover Date.     

The developmental potential of frozen-thawed hamster preimplantation embryos following embryo transfer: Viability of slowly frozen embryos following slow and rapid thawing

Hamster preimplantation embryos were slowly frozen (0.33°C/min) and seeded above 10°C in TC-199 containing 1.5 M-DMSO. These embryos were thawed either slowly (1.5°C/min) or rapidly (90°C/min). The thawed embryos were examined by morphology, trypan blue exclusion and viability after embryo transfer. Slow thawing gave significantly higher viability compared to rapid thawing. The early preimplantation embryos demonstrate higher sensitivity to freezing. The three tests of viability (morphology, trypan blue exclusion and embryo transfer) were found to be positively correlated.