Femoral Strength Changes Faster With Age Than BMD in Both Women and Men: A Biomechanical Study

Although a large number of studies have addressed the age‐related changes in bone mineral density (BMD), there is a paucity of data for the assessment of femoral strength loss with age in both genders. We determined the variation of strength with age in femurs of women and men by mechanical tests on a cohort of 100 cadaveric femurs. In addition, the age‐related neck BMD loss in our cadaveric cohort was found to be similar with BMD loss of four published population‐based studies. Given the strong correlation found in our cadaveric study between BMD and femoral strength, we also estimated the femoral strength of the four populations based on their reported neck BMDs. Our study showed that men's femurs in our cadaveric cohort were stronger than women's femurs by about 800 N at the same BMD level, and by 1750 N at the same age. The strength differences were not explained satisfactorily by the size difference between men's and women's bones. Similar to the findings of clinical studies, the BMD values of men at all ages were larger than that of women. The age‐related loss rates in BMD and strength were not statistically different between the two genders of our cadaveric cohort. After normalization, strength decreased more than 40% faster than BMD. On average, men reached a certain BMD value about 16 years later than women, and for strength about 23 years later, which may explain the higher rate of hip fracture in postmenopausal women. In patient population cohorts men reached a similar BMD value about 16 to 25 years later than women, whereas for estimated strength, sometimes more than 40 years later. © 2015 American Society for Bone and Mineral Research.     

Corneal Confocal Microscopy Identifies Small-Fiber Neuropathy in Subjects With Impaired Glucose Tolerance Who Develop Type 2 Diabetes

OBJECTIVEImpaired glucose tolerance (IGT) through to type 2 diabetes is thought to confer a continuum of risk for neuropathy. Identification of subjects at high risk of developing type 2 diabetes and, hence, worsening neuropathy would allow identification and risk stratification for more aggressive management.RESULTSTen subjects who developed type 2 diabetes had a significantly lower CNFD (P = 0.003), CNBD (P = 0.04), and CNFL (P = 0.04) compared with control subjects at baseline and a further reduction in CNFL (P = 0.006), intraepidermal nerve fiber density (IENFD) (P = 0.02), and mean dendritic length (MDL) (P = 0.02) over 3 years. Fifteen subjects who remained IGT and 5 subjects who returned to normal glucose tolerance had no significant baseline abnormality on CCM or IENFD but had a lower MDL (P < 0.0001) compared with control subjects. The IGT subjects showed a significant decrease in IENFD (P = 0.02) but no change in MDL or CCM over 3 years. Those who returned to NGT showed an increase in CNFD (P = 0.05), CNBD (P = 0.04), and CNFL (P = 0.05), but a decrease in IENFD (P = 0.02), over 3 years.CONCLUSIONSCCM and skin biopsy detect a small-fiber neuropathy in subjects with IGT who develop type 2 diabetes and also show a dynamic worsening or improvement in corneal and intraepidermal nerve morphology in relation to change in glucose tolerance status.     

Development trends for generation of single-chain antibody fragments

Recombinant antibodies are increasingly being employed as therapeutic agents especially in combination with anti-cancer drugs. The single-chain antibody fragments are small antigen-binding proteins which provide the most commonly used antibody formats for diagnostic and therapeutic purposes. These antibody fragments have more rapid tumor penetration and clearance from the serum relative to full-length monoclonal antibodies. There are in vitro antibody-display technologies such as phage display, cell surface display, ribosome display and mRNA display that can be used to isolate high specificity and affinity single-chain antibodies against a wide variety of targets. We review these strategies for generation of stable and active antibody fragments in the present article.     

Surgical management of symptomatic Chiari II malformation in infants and children

Purpose

Variation exists in the surgical methods employed for decompression of Chiari II malformation (CIIM), yet an evaluation of these techniques has not been performed. The purpose of this study was to assess the efficacy of bony decompression (cervical laminectomy alone versus suboccipital craniectomy with laminectomy) with or without dural augmentation for the treatment of symptomatic CIIM.

Methods

Clinical records of children 0–18 years of age who underwent surgical repair of myelomeningocele or CIIM decompression at St. Louis Children’s Hospital (SLCH) from 1990–2011 were reviewed. Signs/symptoms prompting decompression, surgical technique, operative parameters, and clinical outcomes were recorded for analysis.

Results

Thirty-three subjects were treated at SLCH for CIIM decompression. Twenty-six subjects underwent bony decompression only (21 cervical laminectomy alone, 5 suboccipital craniectomy?+?cervical laminectomy) while seven underwent bony decompression with upfront dural augmentation (three cervical laminectomy alone, four suboccipital craniectomy?+?cervical laminectomy). Median follow up was 5.0 years (range, 3 months–19 years). Symptomatic improvement was noted in 20/33 subjects (60.6 %). Sixty-two (61.5 %) percent of children who underwent bony decompression had symptomatic improvement, compared with 57.1 % of those with upfront dural augmentation (p?=?0.37). Estimated blood loss, operative time, and length of perioperative hospital stay appeared lower in the bony decompression group but were not statistically different in this limited cohort.

Conclusions

The results from this series suggest that bony CIIM decompression via tailored cervical laminectomies alone, without suboccipital craniectomy or upfront dural augmentation, is a reasonable initial management approach for decompression of symptomatic CIIM.