Ultrasound-Derived Nerve Cross-Sectional Area in Extremes of Height and Weight.

BACKGROUND AND PURPOSE: There is a lack of consensus in the literature as to which body habitus parameter most influences nerve cross-sectional area (CSA). This study was specifically designed to determine if height or weight is more influential. METHODS: Fifteen young healthy participants, 8 extremely tall and 7 heavy, with no peripheral nerve symptoms were recruited. The tall cohort consisted of males who were 74 inches or taller and females who were 68 inches or taller. The heavy cohort consisted of males who were 274 lbs or heavier and females who were 200 lbs or heavier. Measurements were obtained bilaterally at 7 sites using neuromuscular ultrasound: median nerve at the wrist and mid-forearm, ulnar at the elbow, radial at the spiral groove, fibular at the knee, tibial at the ankle, and sural at the ankle. The nerve CSA at each site was measured by tracing of the nerve using the "freehand" trace function of the ultrasound device. RESULTS: Weight tightly correlated with nerve CSA (R2 = .69, P < .001), while height did not significantly predict CSA (R2 = .10, P = .244). Nerve CSA for tall participants did not systematically deviate from an historical control group. Conversely, with exception of the tibial and sural nerves at the ankle, all nerve CSAs for heavy participants were higher than in the control group. CONCLUSION: Weight was found to be the body habitus parameter that most influences nerve CSA. This will inform clinicians when using nerve imaging to evaluate participants at either extreme of weight.

Combinatorial effect of Si4+, Ca2+, and Mg2+ released from bioactive glasses on osteoblast osteocalcin expression and biomineralization.

Osteocalcin (OCN) expression is an essential osteogenic marker of successful bone regeneration therapies. This study hypothesizes that Si(4+) and Ca(2+) combinatorial released by bioactive glass enhance osteoblast biomineralization through up-regulation of OCN expression; and Mg(2+) release delays such enhancement. Osteoblasts (MC3T3-E1) were treated with ionic products of bioactive glass dissolution (6P53-b experimental bioactive glass and 45S5 commercial Bioglass™). Results showed that gene expressions, including OCN and its up-stream transcription factors (Runx2, ATF4, MSX1, SP7/OSX), growth factors and signaling proteins (BMP2, BMP6, SMAD3), were enhanced in both 45S5 and 6P53-b glass conditioned mediums (GCMs). This up-regulation led to enhanced mineral formation by 45S5 glass conditioned mediums ([GCM], Si(4+)+Ca(2+)) after 20 days, and by 45S5 GCM and 6P53-b GCM (Si(4+)+Ca(2+)+Mg(2+)) after 30 days. In examining the extracellular matrix generated by cells when exposed to each GCM, it was found that 45S5 GCM had slightly elevated levels of mineral content within ECM as compared to 6P53-b GCM after 30 days while control treatments exhibited no mineral content. The formation of well-defined mineralized nodules (distinct PO4(3-) [960 cm(-1)] and CO3(2-) [1072 cm(-1)] peaks from Raman Spectra) was observed for each GCM as the soluble glass content increased. In examining the individual and combined ion effects between Si(4+), Ca(2+), and Mg(2+), it was found Mg(2+) down-regulates OCN expression. Thus, ions released from both 45S5 and 6P53-b bioactive glasses up-regulate OCN expression and biomineralization while 6P53-b GCM Mg(2+) release down-regulated OCN expression and delayed osteoblast biomineralization. These results indicate that Si(4+), Ca(2+), and Mg(2+) combinatorially regulate osteoblast OCN expression and biomineralization.