Age-dependent changes in the mechanical properties of tail tendons in TGF-beta inducible early gene-1 knockout mice.

The purpose of this study is to investigate age-dependent changes in the architecture and mechanical properties of tendon in TGF-beta inducible early gene-1 (TIEG) knockout mice. Wild-type and TIEG knockout mice, aged 1, 2, and 15 mo, were used. The mechanical properties of tail tendons isolated from these mice were determined using uniaxial tensile ramp (0.05 mm/s) and relaxation (5 mm/s) tests, with a strain of 10%. Mechanical parameters (Young's modulus from the ramp test; fast and static stresses from the relaxation test) were measured and recorded. The structure of the tail tendon fascicle was characterized by transmission electron microscopy. The results of the mechanical testing revealed no significant difference between the knockout and wild-type groups at 1 or 15 mo of age. However, the fascicles of the knockout mice at 3 mo of age exhibited decreased fast and static stresses compared with those of the wild-type mice. Electron microscopy revealed an increase in fibril size in the knockout mouse tendons relative to wild-type controls at 1 and 3 mo of age. These data indicate an important role for TIEG in tendon microarchitecture and strength in adult mice.     

Influence of wall teichoic acid on lysozyme resistance in Staphylococcus aureus

Staphylococcus aureus peptidoglycan (PG) is completely resistant to the hydrolytic activity of lysozyme. Here we show that modifications in PG by O acetylation, wall teichoic acid, and a high degree of cross-linking contribute to this resistance.     

Faster Metabolite 1H Transverse Relaxation in the Elder Human Brain

¹H magnetic resonance spectroscopy (MRS) is unique among imaging modalities because signals from several metabolites are measured during a single examination period. Each metabolite reflects a distinct intracellular process. Furthermore transverse (T₂) relaxation times probe the viability of the cell microenvironment, e.g., the viscosity of the cellular fluids, the microscopic susceptibility distribution within the cells, and the iron content. In this study, T₂s of brain metabolites were measured in the occipital lobe of eighteen young and fourteen elderly subjects at a field strength of 4 tesla. The T₂s of N-acetylaspartate, total creatine, and total choline were 23%, 16% and 10% shorter in elderly than in young subjects. The findings of this study suggest that noninvasive detection of T₂ provides useful biological information on changes in the cellular microenvironment that take place during aging.     

Whole body vibration increases area and stiffness of the flexor carpi ulnaris tendon in the rat

Whole body vibration (WBV) has been extensively studied as an anabolic stimulus for bone and muscle. Therapeutic WBV delivers low magnitude, high frequency vibrations to tissues, eliciting biological and structural responses. This study investigated the effect of 0.3G (Peak-to-Peak), 30Hz sinusoidal vibration on intact flexor carpi ulnaris tendons in rats. Experimental rats were subjected to twenty minutes of WBV daily for five days a week for a total of five weeks. The tendon cross-sectional area and the structural properties of the muscle-tendon-bone unit under tensile loading to failure were evaluated. Initial body weights were similar between the groups and the mean change in body weight of the animals of each group did not differ. The cross-sectional area of the tendons of the vibrated animals was found to be 32% greater (P<0.05) than the controls and the structural stiffness of the vibrated tendons was found to be 41% greater (P<0.05) than the controls. For specimens that failed in the midsubstance of the tendon, a trend (P=0.087) for increased ultimate load was observed in the vibrated tendons compared to the controls. No differences in material properties were observed except for the strain to ultimate load, which was reduced 22% in the vibrated group. These initial findings suggest that vibration may serve as an anabolic stimulus to tendon similar to its effects on bone and muscle. These findings are important as they open the potential that low magnitude, high frequency vibration might serve as a means to accelerate tendon healing.     

Raman spectroscopy of xylitol uptake and metabolism in Gram-positive and Gram-negative bacteria

Visible-wavelength Raman spectroscopy was used to investigate the uptake and metabolism of the five-carbon sugar alcohol xylitol by Gram-positive viridans group streptococcus and the two extensively used strains of Gram-negative Escherichia coli, E. coli C and E. coli K-12. E. coli C, but not E. coli K-12, contains a complete xylitol operon, and the viridans group streptococcus contains an incomplete xylitol operon used to metabolize the xylitol. Raman spectra from xylitol-exposed viridans group streptococcus exhibited significant changes that persisted even in progeny grown from the xylitol-exposed mother cells in a xylitol-free medium for 24 h. This behavior was not observed in the E. coli K-12. In both viridans group streptococcus and the E. coli C derivative HF4714, the metabolic intermediates are stably formed to create an anomaly in bacterial normal survival. The uptake of xylitol by Gram-positive and Gram-negative pathogens occurs even in the presence of other high-calorie sugars, and its stable integration within the bacterial cell wall may discontinue bacterial multiplication. This could be a contributing factor for the known efficacy of xylitol when taken as a prophylactic measure to prevent or reduce occurrences of persistent infection. Specifically, these bacteria are causative agents for several important diseases of children such as pneumonia, otitis media, meningitis, and dental caries. If properly explored, such an inexpensive and harmless sugar-alcohol, alone or used in conjunction with fluoride, would pave the way to an alternative preventive therapy for these childhood diseases when the causative pathogens have become resistant to modern medicines such as antibiotics and vaccine immunotherapy.     

Investigation of photosensitively bioconjugated targeted quantum dots for the labeling of Cu/Zn superoxide dismutase in fixed cells and tissue sections

This study presents the development of targeted and antibody cross-linked QDs and explores whether these bioconjugates could specifically and effectively label Cu/Zn superoxide dismutase (SOD1) on fixed cells and tissues. QD-antibody conjugation was achieved by using our previously invented AmiNoacid (monomer) Decorated and Light Underpining Conjugation Approach (ANADOLUCA) method. In this method, we have used a photosensitive aminoacid monomer having ruthenium complex which is a synthetic and inexpensive material for the preparation of bioconjugates. Its specificity was demonstrated by extracting the active enzyme from rat liver lysate by using the bioconjugate. It provided accurate antibody orientation, high specificity and mechanic stability. The protocol steps for QD-antibody conjugation and specimen preparation were described in detail. The nanobioconjugates were prepared under mild conditions (for example in day light), independent of pH and temperature, without affecting conformation and function of protein. This protocol is simple, inexpensive and can be successfully adapted to detect other targets on different cell types and tissues.