Menopause is associated with lumbar disc degeneration: a review of 4230 intervertebral discs.

OBJECTIVE: The main objective of this study was to investigate, in a population of normal postmenopausal women, the association between menopause and severity of lumbar disc degeneration from the first lumbar to the first sacral vertebra on magnetic resonance imaging. METHODS: Between January 2010 and May 2013, 846 normal women and 4230 intervertebral discs were retrospectively analyzed. Age, height, weight and years since menopause (YSM) were recorded. Disc degeneration was evaluated using the modified Pfirrmann grading system. RESULTS: Compared to premenopausal and perimenopausal women, postmenopausal women had more severe disc degeneration after removal of age, height and weight effects (p < 0.0001). Postmenopausal women were divided into six subgroups for every 5 YSM. When YSM was below 15 years, there was a significant difference between every two groups, i.e. groups 1-5 YSM, 6-10 YSM and 11-15 YSM (p < 0.01). A positive trend was observed between YSM and severity of disc degeneration, respectively, i.e. L1/L2 (r = 0.235), L2/L3 (r = 0.161), L3/L4 (r = 0.173), L4/L5 (r = 0.146), L5/S1 (r = 0.137) and all lumbar discs (r = 0.259) (p < 0.05 or 0.01). However, when YSM was above 15, there was no difference, i.e. groups 16-20 YSM, 21-25 YSM and 26-30 YSM (p > 0.05), and the significance correlation also disappeared (p > 0.05). CONCLUSION: Menopause is associated with disc degeneration in the lumbar spine. The association almost entirely occurred in the first 15 years since menopause, suggesting estrogen decrease may be a risk factor for lumbar disc degeneration.

Assessment of the nutritive value of whole corn stover and its morphological fractions.

This study investigated the chemical composition and ruminal degradability of corn stover in three maize-planting regions in Qiqihaer, Heilongjiang Province, China. The whole stover was separated into seven morphological fractions, i.e., leaf blade, leaf sheath, stem rind, stem pith, stem node, ear husk, and corn tassel. The assessment of nutritive value of corn stover and its fractions was performed based on laboratory assays of the morphological proportions, chemical composition, and in situ degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF). The chemical composition of corn stover was significantly different from plant top to bottom (p<0.05). Among the whole corn stover and seven morphological fractions, leaf blade had the highest crude protein (CP) content and the lowest NDF and ADF contents (p<0.05), whereas stem rind had the lowest CP content and the highest ADF and acid detergent lignin (ADL) contents (p<0.05). Ear husk had significantly higher NDF content and relatively lower ADL content than other corn stover fractions. Overall, the effective degradability of DM, NDF, and ADF in rumen was the highest in leaf blade and stem pith, followed by ear husk. The results indicate that leaf blade, ear husk, and stem pith potentially have higher nutritive values than the other fractions of corn stover. This study provides reference data for high-efficiency use of corn stover in feeding ruminants.