Comparison of the invasiveness of conventional discectomy and microendoscopic discectomy for lumbar disc herniation: Differences in the methods of approach.

INTRODUCTION: The aim of this study was to investigate whether differences in the methods of approach to the vertebral arch influence the invasiveness of conventional discectomy and microendoscopic discectomy (MED). METHODS: In this study, 41 Wistar rats were divided into four groups: controls (no surgery) (n = 10), shams (skin incision only) (n = 11), MED (n = 10), and conventional discectomy (n = 10). We performed ethological and blood biochemical examinations for three of the groups, excluding the control group, and a histological examination for three of the groups, excluding the sham group. In the ethological examination, we measured the threshold of postoperative pain using the von Frey test. In the blood chemical examination, we measured blood creatine phosphokinase and inflammatory cytokines, and compared the severity of tissue damage by histological examination using hematoxylin-eosin and immunohistochemical staining. RESULTS: The conventional discectomy group showed a significantly lower threshold of postoperative pain, compared with the MED group (P < 0.05). Blood biochemical investigation revealed that the creatine phosphokinase (P < 0.05) and tumor necrosis factor-α levels (P < 0.05) of the conventional discectomy group were significantly higher than those in the MED group. In the histological examination, it was found that a wide range of paraspinal muscle damage occurred in the conventional discectomy group (P < 0.05) and that the damage was mostly confined to the periosteum and nearby nerve endings. CONCLUSION: MED was found to be less invasive than conventional discectomy based on ethological, blood biochemical, and histological examinations.

Asymmetric total syntheses of (+)-cheimonophyllon e and (+)-cheimonophyllal.

The highly enantiocontrolled total syntheses of natural (+)-cheimonophyllon E (5) and (+)-cheimonophyllal (6), biologically intriguing oxygenated bisabolane-type sesquiterpenoids, have been completed. The present synthetic strategy featured the use of an asymmetric aldol-type reaction for preparing in the first synthetic step an optically active 6-C-substituted 3-methyl-2-cyclohexenone derivative. Thus, a Mukaiyama aldol reaction of 1-methyl-3-silyloxy-1,3-cyclohexadiene 31 with alpha,beta-unsaturated aldehyde 11 in the presence of a chiral (acyloxy)borane (CAB)-type Yamamoto catalyst 33 proceeded with high levels of both diastereo- and enantioselectivities. The predominant aldol adduct, syn-9, was transformed into gamma,delta-epoxy allylic alcohol 8 by a nine-step sequence, including the substrate-controlled 1,2-reduction of enone, syn-12, also the epoxidation of allylic alcohol 15. Epoxy-alcohol 8 underwent 5-exo-cyclization in a high regioselective manner under acidic conditions to produce a bicyclic key intermediate (+)-7, which was eventually efficiently converted to (+)-cheimonophyllon E (5) or (+)-cheimonophyllal (6).