Synthesis of Polyether, Poly(Ether Carbonate) and Poly(Ether Ester) Polyols Using Double Metal Cyanide Catalysts Bearing Organophosphorus Complexing Agents.

We developed a series of Zn(II)-Co(III) double metal cyanide (DMC) catalysts with exceptional activity for the ring-opening polymerization of various cyclic monomers by employing diverse organophosphorus compounds as complexing agents (CAs). The chemical structure and composition of DMC catalysts were investigated by commonly used analysis such as infrared and X-ray photoelectron spectroscopies, and elemental analysis combining with in situ NMR analysis to determine the complexation types of organophosphorus compounds the catalyst framework. The resulting catalysts exhibited very high turnover frequencies (up to 631.4 min-1) in the ring-opening polymerization (ROP) of propylene oxide and good efficiency for the ROP of ε-caprolactone. The resultant polyester polyols are suitable to use as an macroinitiator to produce well-defined poly(ester ether) triblock copolymers of 1800-6600 g mol-1 and dispersity of 1.16-1.37. Additionally, the DMC catalysts bearing organophosphorus compounds CAs exhibited remarkable selectivity for the copolymerization of PO with CO2, yielding poly(ether carbonate) polyols with carbonate contents up to 34.5%. This study contributes to the development of efficient DMC catalytic systems that enable the synthesis of high-quality polyols for various applications.

Feasibility of Using Fat Degeneration of Lumbar Extensor Muscle as an Alternative Diagnostic Criterion for Sarcopenia in Patients with Osteoporotic Vertebral Fractures.

STUDY DESIGN: Feasibility study. PURPOSE: To investigate the feasibility of using fat degeneration of lumbar extensor muscle (LEM) as an alternative diagnostic criterion for sarcopenia in patients with osteoporotic vertebral fractures. OVERVIEW OF LITERATURE: Although sarcopenia has been gaining increased attention among researchers and healthcare practitioners, there is uncertainty about the association between sarcopenia and fat degeneration of LEM. METHODS: In this study, 33 patients with osteoporotic vertebral fractures (group 1) and 29 patients without such fractures (group 2) were enrolled. Sarcopenia was diagnosed in accordance with the Asian Working Group for Sarcopenia (AWGS) criteria, including assessment of extremity muscle mass using dual-energy X-ray absorptiometry, grip strength, and gait speed. The bone mineral density and fat degeneration of LEM were investigated using magnetic resonance imaging. RESULTS: The mean rates of fat degeneration of LEM and the skeletal muscle index were 38.3% and 5.5 kg/m2 in group 1 and 28.9% and 6.3 kg/m2 in group 2, respectively. The fat degeneration of LEM was negatively correlated with gait speed (r=-0.44, p=0.01) and handgrip strength (r=-0.37, p=0.01). The fat degeneration of LEM also demonstrated a significant relationship with osteoporotic vertebral fractures (p=0.01). Receiver operating characteristic curve analysis between fat degeneration of LEM and osteoporotic vertebral fractures showed that the cut-off value of fat degeneration was 31.9% (sensitivity=0.67, specificity=0.66). There was a positive correlation between sarcopenia defined by the AWGS and that defined by the 31.90% cut-off value of fat degeneration of LEM instead of extremity muscle mass (r=0.46, p=0.01). CONCLUSIONS: These results suggest the feasibility of using fat degeneration of LEM as an alternative diagnostic criterion for sarcopenia in patients with osteoporotic vertebral fractures. A cut-off value of fat degeneration of LEM of 31.9% was shown to be useful for diagnosing osteoporotic vertebral fractures.

The Validation of Ultrasound-Guided Target Segment Identification in Thoracic Spine as Confirmed by Fluoroscopy.

BACKGROUND: The role of ultrasound in the thoracic spine has been underappreciated, partly because of the relative efficacy of the landmark-guided technique and the limitation of imaging through the narrow acoustic windows produced by the bony framework of thoracic spine. The aim of this study was to make a comparison between the 12th rib and the spinous process of C7 as a landmark for effective ultrasound-guided target segment identification in the thoracic spine. METHODS: Ultrasonography of 44 thoracic spines was performed and the same procedure was carried out 1 week later again. The target segments (T3-4, T7-8, and T10-11) were identified using the 12th rib (group 1) or the spinous process of C7 (group 2) as a starting landmark. Ultrasound scanning was done proximally (group 1) or distally (group 2) toward the target transverse process and further medially and slightly superior to the target thoracic facet. Then, a metal marker was placed on the T3-4, T7-8, and T10-11 and the location of each marker was confirmed by fluoroscopy. RESULTS: In the total 132 segments, sonographic identification was confirmed to be successful with fluoroscopy in 84.1% in group 1 and 56.8% in group 2. Group 1 had a greater success rate in ultrasound-guided target segment identification than group 2 (p = 0.001), especially in T10-11 (group 1, 93.2%; group 2, 43.2%; p = 0.001) and T7-8 (group 1, 86.4%; group 2, 56.8%; p = 0.002). The intrarater reliability of ultrasound-guided target segment identification was good (group 1, r = 0.76; group 2, r = 0.82), showing no difference between right and left sides. Ultrasound-guided target segment identification was more effective in the non-obese subjects (p = 0.001), especially in group 1. CONCLUSIONS: Ultrasound-guided detection using the 12th rib as a starting landmark for scanning could be a promising technique for successful target segment identification in the thoracic spine.

Feasibility of nerve stimulator as a supplemental aid for lumbar transforaminal epidural block.

BACKGROUND: The purpose of this study was to evaluate the clinical feasibility of an electric nerve stimulator in a lumbar transforaminal epidural block. METHODS: Using an electric nerve stimulator, transforaminal epidural blocks were performed in 105 segments of 49 patients who presented with lower back pain with radiating pain to lower extremities. The contrast medium was injected to delineate the nerve root after positioning an insulated needle at the intervertebral foramen under fluoroscopic guidance. Then, the nerve root was electrically stimulated with the insulated needle to confirm whether or not the same radiating pain was evoked. RESULTS: Of the 105 foraminal segments, the same radiating pain was evoked at 0.5 mAh in 47 segments (44.8%), at 1.0 mAh in 22 (21.0%), at 1.5 mAh in 3 (2.9%), at 2.0 mAh in 15 (14.3%), at 2.5 mAh in 4 (3.8%), and at 3.0 mAh in 5 (4.8%). No response was observed in 9 segments (8.6%). The fluoroscopy revealed successful positioning of the needle in the patients with an evoked radiating pain over 2.0 mAh. The visual analogue scale (VAS) obtained for pain improved from a mean of 7.5 to 2.7 after the block (p = 0.001). In the 9 cases without response to electrical stimulation, the patients showed an improvement on VAS from 7.8 to 3.4 (p= 0.008) also. CONCLUSIONS: A nerve stimulator can help to predict the accuracy of needle positioning as a supplemental aid for a successful lumbar transforaminal epidural block. It is sufficient to initiate a proper stimulation amplitude of the nerve at 2 mAh.

The Effect of Hydroxyapatite Coating on Long-term Results of Total Hip Arthroplasty with Hydroxyapatite-coated Anatomic Femoral Stem.

PURPOSE: To evaluate the clinical and radiological results, as well as the survival rate, associated with total hip arthroplasty using a hydroxyapatite (HA)-coated anatomical femoral stem at a follow-up of ≥12 years. MATERIALS AND METHODS: From April 1992 to May 1997, 86 patients (102 hips) underwent total hip arthroplasty with a HA-coated ABG I (Anatomical Benoist Giraud; Howmedica) hip prosthesis. The average age at the time of surgery was 53.4 years and the mean duration of follow-up was 17.1 years (range, 12.1-21.0 years). The Harris hip score (HHS) and radiographic assessments of thigh pain were used to evaluate the clinical results. We observed osteointegration, cortical hypertrophy, reactive line, calcar resorption and osteolysis around the femoral stems. The survival rate of the femoral stems was evaluated by using the span of time to a revision operation for any reasons was defined as the end point. RESULTS: The mean HHS was 50.5 preoperatively and 84.2 at the time of last follow-up. Osteolysis only around the HA-coated proximal portion of the femoral stem was observed in 72 hips, cortical hypertrophy all around the distal portion of the femoral stem was observed in 38 hips, and calcar resorption was observed in 44 hips. A reactive line was observed in 13 hips, but was unrelated to component loosening. Stem revision operations were performed in 24 (23%) hips due to osteolysis (14 hips), fracture (5 hips) and infection (5 hips). The femoral stem survival rate was 75% over the mean duration of follow-up. CONCLUSION: Total hip arthroplasty using a HA-coated anatomical femoral stem showed necessitated a high rate of revision operations due to osteolysis around the femoral stem in this long term follow-up study.