Biology subjects

Vo, N. T.

Publications and source records attributed to Vo, N. T..

3 recordsLinked to original sources

bioRxiv2024

Runaway resorption of microcracks contributes to age-related hip-fracture patients

Microdefects, including microcracks and resorption trenches, may be important contributors to bone fragility. 3D microdefect morphology was imaged using synchrotron micro-CT to develop a classification system for investigating the relationship with bone mechanics and hip-fractures. Femoral heads from ageing hip-fracture patients (n=5, 74-82 years) were compared to ageing non-fracture controls (n=5, 72-84 years). Two trabecular cores were prepared from the chiasma; one was imaged using synchrotron micro-CT to measure microdefects and one was mechanically tested to measure tensile strength. Morphological and mechanical data were compared and correlated using Mann Whitney U test and Pearsons rank correlation. Microdefects varied and were classified into four categories based on shape and measurable parameters. Hip-fracture donors exhibited significantly higher density of all microdefects (p<0.05). Microdefect volume was strongly negatively correlated with ultimate tensile strength (p<0.05) and stiffness (p<0.05). Microdefects might contribute to loss of bone strength and fragility fracture via runaway resorption. Microcracks could promote focussed osteoclastic resorption and the formation of resorption pits which create stress risers leading to the re-formation of microcracks under continued load. CT-based classification methods should be used to explore the complex interaction between microdefects, metabolism, and bone fracture mechanics.

bioengineering↗

bioRxiv2022

MYXOBACTERIA FROM VIETNAM: ISOLATION, PHYLOGENETIC ANALYSIS AND BIOPROSPECTION

Forty-three myxobacterial strains were isolated and identified from 20 soil samples collected in Vietnam. The information on morphological characteristics and 16S ribosomal gene sequencing showed that these strains were designated to seven genera belonging to Angiococcus, Archangium, Chondromyces, Corallococcus, Cystobacter, Melittangium, and Myxococcus, in suborder Cystobacterineae and Sorangiineae. The phylogenetic tree was constructed to clarify the genetic relationship between myxobacterial isolates. Myxobacteria were cultured, and crude extracts were obtained after 10-day fermentation in P-medium in the presence of the Amberlite XAD 16N adsorbent resin. Elution was carried out with acetone and methanol to obtain the crude extracts. Evaluation of antioxidant activity used the DPPH and ABTS assay, the minimum inhibitory concentration values were determined by the microdilution method. The total extract from CT21 had the highest total antioxidant activity (IC50 = 52.34 {+/-} 1.47 {micro}g/mL, 30.28 {+/-} 0.74 {micro}g/mL for DPPH and ABTS assays, respectively). The other potential strain was TG131 and GL41 that IC50 values were 40.28 {+/-} 1.13 and 57.24 {+/-} 1.52 {micro}g/mL, respectively (by the DPPH method), and 48.35 {+/-} 0.58 and 42.76 {+/-} 0.50 {micro}g/mL, respectively (by the ABTS method). Interestingly, 100% isolated myxobacterial strains show inhibitory activity against at least one of the tested microorganisms. The potential antimicrobial strain was GL41, which inhibited all tested microorganisms, and the MIC values were 1 {micro}g/mL against MRSA, MSSA, S. faecalis, C. albicans, and A. niger. The highest active strains were members of Myxococcus sp. genus.

microbiology↗

bioRxiv2018

Parallel comparison of pre-conditioning and post-conditioning effects in human cancers and keratinocytes upon acute gamma irradiation

PURPOSETo determine and compare the effects of pre-conditioning and post-conditioning towards gamma radiation responses in human cancer cells and keratinocytes\n\nMATERIALS AND METHODSThe clonogenic survival of glioblastoma cells (T98G), keratinocytes (HaCaT), and colorectal carcinoma cells (HCT116 p53+/+ and p53-/-) was assessed following gamma ray exposure from a Cs-137 source. The priming dose preceded the challenge dose in pre-conditioning whereas the priming dose followed the challenge dose in post-conditioning. The priming dose was either 5 mGy or 0.1 Gy. The challenge dose was 0.5 - 5 Gy.\n\nRESULTSIn both pre- and post-conditioning where the priming dose was 0.1 Gy and the challenge dose was 4 Gy, RAR developed in T98G but not in HaCaT cells. In HCT116 p53+/+, pre-conditioning had either no effect or a radiosensitizing effect and whereas post-conditioning induced either radiosensitizing or radioadaptive effect. The different observed outcomes were dependent on dose, the time interval between the priming and challenge dose, and the time before the first irradiation. Post-conditioning effects could occur with a priming dose as low as 5 mGy in HCT116 p53+/+ cells. When HCT116 cells had no p53 protein expression, the radiosensitizing or radioadaptive response by the conditioning effect was abolished.\n\nCONCLUSIONSThe results suggest that radiation conditioning responses are complex and depend on at least the following factors: the magnitude of priming/challenge dose, the time interval between priming and challenge dose, p53 status, cell seeding time prior to the first radiation treatment. This work is the first parallel comparison demonstrating the potential outcomes of pre- and post-conditioning in different human cell types using environmentally and medically relevant radiation doses.

cancer biology↗