1306-km 20x124.8-Gb/s PM-64QAM transmission over PSCF with net SEDP 11,300 (b ∙ km)/s/Hz using 1.15 samp/symb DAC

We demonstrated the transmission of a Nyquist-WDM signal based on PM-64QAM modulation in an EDFA-only submarine configuration composed of 54.4 km-long fiber spans: 20 channels at 124.8-Gb/s were propagated over 1306 km of low-loss pure-silica-core fiber (PSCF). Thanks to an aggressive digital spectral shaping, we achieved a raw spectral efficiency (SE) of 10.4 b/s/Hz, corresponding to 8.67 b/s/Hz net SE when considering a 20% FEC overhead. Transmitter DACs are operated at a record-low 1.15 samples/symbol, enabled by the insertion of advanced anti-alias filters. The achieved SE-times-distance product was 11,327 (b ∙ km)/(s ∙ Hz), the highest reported so far for PM-64QAM. Combining the experimental results with the performance predictions obtained using an analytical model of nonlinear propagation in uncompensated coherent optical systems (the so-called "GN-model"), we show that PM-64QAM is a realistic option for ultra-high capacity systems in the 1,000 km range, carrying up 40 Tb/s in the C-band.

In not only vertebroplasty but also kyphoplasty, the resolution of vertebral deformities depends on vertebral mobility

BACKGROUND AND PURPOSE

It has not been clarified whether the postoperative resolution of vertebral deformities achieved by KP are superior to those achieved by VP. We compared the outcomes of KP and VP, taking into account the presence of vertebral mobility, to determine whether the balloon inflation in KP may contribute to postoperative resolution of the vertebral deformities in patients with VCFs.

MATERIALS AND METHODS

The subjects had 34 vertebral bodies treated by VP, and 43 vertebral bodies treated by KP. In all patients, preoperative dynamic imaging was performed to assess the presence of vertebral mobility. First, the vertebral height restoration and kyphotic change were compared between the VP and KP groups. Then, the patients were further divided into 2 groups on the basis of the presence of vertebral mobility, and they were compared within and between the VP and KP groups in relation to the presence of vertebral mobility.

RESULTS

Overall, no significant differences were observed in either the vertebral height restoration or kyphotic change between the VP and KP groups (P > .20). Preoperative dynamic imaging identified 19 vertebral bodies each with vertebral mobility in the VP (56%) and KP groups (44%) (P = .21). Within the VP and KP groups, the vertebral height restoration and kyphotic changes were significantly better in patients with vertebral mobility than in those without (P < .01). There were no significant differences between the 2 treatment groups after adjustment for the presence of vertebral mobility (P > .30).

CONCLUSIONS

In both the VP and KP groups, the vertebral height restoration and kyphotic change largely depended on the preoperative vertebral mobility. The use of the balloon itself contributed little to resolution of the vertebral deformities.

Validity of intervertebral bone cement infusion for painful vertebral compression fractures based on the presence of vertebral mobility

BACKGROUND AND PURPOSE

It is uncertain whether analgesic effects of vertebroplasty in patients with painful VCF are actually attributable to intervertebral cement infusion. This study aims to assess the validity of cement infusion performed for pain relief based on the presence or absence of pseudoarthrosis.

MATERIALS AND METHODS

We compared therapeutic effects between PVP and vertebral perforation without bone cement infusion in patients with painful VCF. The subjects were 64 patients undergoing PVP (PVP group) and 67 undergoing vertebral perforation (perforation group). In all patients, preoperative dynamic radiography was performed to assess the presence of vertebral mobility. Patients were classified into 2 groups, those with and those without vertebral mobility, and changes in VAS and ADL scores before and after surgery were compared between the PVP and perforation groups.

RESULTS

Regarding patients with vertebral mobility, VAS improved during the 3 months immediately after surgery in the PVP group compared with the perforation group (P < .05). Although no significant difference in postoperative ADL scores was observed between the 2 treatment groups, the scores 3 months after surgery were better in the PVP group than in the perforation group. Meanwhile, in the subgroup of patients without vertebral mobility, both treatments produced marked pain relief, but the difference was not significant (P > .05). Moreover, there was no difference in ADL scores between the 2 treatment groups.

CONCLUSIONS

Intervertebral cement infusion exerts analgesic effects in patients with VCF with pseudoarthrosis. However, in those without vertebral mobility, the analgesic effects of vertebroplasty are the same regardless of bone cement infusion.

Tapering of the cervical spinal canal in patients with Chiari I malformations

BACKGROUND AND PURPOSE

Upper cervical spinal canal dimension may have a role in abnormal CSF dynamics in patients with Chiari I malformation. We attempted to measure spinal canal tapering from anteroposterior spinal canal dimensions in patients with Chiari I.

MATERIALS AND METHODS

Twenty-one patients with Chiari I malformation, including 12 with syringomyelia and 7 patients with IS were identified from a local registry. Age- and sex-matched control subjects with cervical spine MR imaging findings reported as normal were selected from the PACS. The anteroposterior diameter of the spinal canal was measured at C1-C7 on T2-weighted sagittal MR images. The taper ratio of the spinal canal was calculated with the regression line. Goodness of fit was calculated as R(2). Differences between patients with Chiari I and other patients were tested for significance with Kruskal-Wallis tests and multivariate analysis.

RESULTS

Taper ratios averaged -0.6 ± 0.3 mm/level in the patients with Chiari and syrinx, -0.4 ± 0.2 mm/level (mean ± 1 SD) in the patients with Chiari without syrinx, and -0.3 ± 0.5 mm/level in the patients with IS; control groups had average taper ratios of -0.3 ± 0.2 mm/level. Mean R(2) equaled 0.43. Taper ratios in patients with Chiari and syringomyelia differed significantly from those in the control group (P = .003). Taper ratios in the patients with Chiari without syrinx and in patients with IS did not differ significantly from their matched control groups (P = .60 and 0.76, respectively).

CONCLUSIONS

Patients with Chiari I and a syrinx have steeper tapering of the upper cervical spinal canal than matched controls.

Metamagnetic behavior and Kondo breakdown in heavy-fermion CeFePO

We report that nonmagnetic heavy-fermion (HF) iron oxypnictide CeFePO with two-dimensional XY-type anisotropy shows a metamagnetic behavior at the metamagnetic field H(M)≃4  T perpendicular to the c axis and that a critical behavior is observed around H(M). Although the magnetic character is entirely different from that in other Ce-based HF metamagnets, H(M) in these metamagnets is linearly proportional to the inverse of the effective mass, or to the temperature where the susceptibility shows a peak. This finding suggests that H(M) is a magnetic field breaking the local Kondo singlet, and the critical behavior around H(M) is driven by the Kondo breakdown accompanied by the Fermi-surface instability.

Comparative study of percutaneous vertebral body perforation and vertebroplasty for the treatment of painful vertebral compression fractures

BACKGROUND AND PURPOSE

Percutaneous vertebral body perforation is a new technique for treating painful VCFs. Herein, we compare the therapeutic effect of vertebral perforation and conventional vertebroplasty for treating VCFs.

MATERIALS AND METHODS

One hundred eight patients with single painful VCFs were assigned to undergo vertebral perforation (perforation group) or vertebroplasty (PVP group). Clinical outcomes were assessed by using the VAS. The associations of analgesic effect and clinical factors were also analyzed by multivariate regression. Plain radiographs were used to quantify the progression of vertebral body compression after surgery and to evaluate cement leakage and new vertebral fractures. The median follow-up time was 10 months.

RESULTS

Baseline characteristics were similar in the 2 groups. No factors correlated with analgesic effects in the PVP group. The analgesic effect of vertebral perforation was, however, related to the preoperative severity of vertebral compression and was low in patients with severe deformity (P < .05). Among patients with preoperative vertebral percentage of compression below 30%, there were no significant differences between the 2 groups in analgesic effect at any postoperative intervals. Progression of vertebral compression after surgery occurred in 22.2% and 16.0% of treated vertebrae in the perforation and PVP groups, respectively (P = .38). Respectively, 3.7% and 20.0% of the perforation and PVP groups had new postoperative fractures during follow-up (P < .05). There were no other complications.

CONCLUSIONS

Vertebral perforation was safe and effective for painful VCFs with slight compression. However, vertebroplasty should be considered for patients with marked vertebral body compression.

A comparison between SSMF and large-A(eff) Pure-Silica core fiber for ultra long-haul 100G transmission

We compare the transmission performance of 112-Gb/s POLMUX-QPSK modulation over large-A(eff) Pure-Silica core fiber and SSMF using EDFA-only amplification. The higher nonlinear threshold of the large-A(eff) Pure-Silica core fiber allows for a 55% increase in transmission distance. By using back-propagation an additional 10% increase is observed. In case spans with equal length for both fiber types and two splices per span only would have been used, resulting in a lower span loss for the large-A(eff) Pure-Silica core fiber, the total increase grows to 85%.

Natural history of MELAS associated with mitochondrial DNA m.3243A>G genotype

OBJECTIVE

To describe the natural history of clinical and laboratory features associated with the m.3243A>G mitochondrial DNA point mutation. Natural history data are needed to obtain prognostic information and for clinical trial planning.

METHODS

We included 85 matrilineal relatives from 35 families with at least 2 visits in this prospective cohort study. Thirty-one were fully symptomatic with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), and 54 were carrier relatives. Evaluations included standardized questionnaires (medical history and daily living functioning), physical examination, neuropsychological testing, and a battery of imaging and laboratory tests. We evaluated changes in clinical and laboratory features over time and survival. Outcomes are reported over a follow-up period of up to 10.6 years (mean 3.8 ± 2.2 years for patients and 5.5 ± 3.0 for carrier relatives).

RESULTS

Neurologic examination, neuropsychological testing, and daily living scores significantly declined in all patients with MELAS, whereas no significant deterioration occurred in carrier relatives. Cerebral MRI scores declined significantly in patients with MELAS. Magnetic resonance spectroscopy estimates of lactate in the lateral ventricles increased over time, and high lactate was associated with increased mortality. Symptom onset in childhood often was associated with worse outcome. Patients with MELAS had a greater death rate than carrier relatives.

CONCLUSIONS

Patients with MELAS carrying the m.3243A>G mutation show a measurable decline in clinical and imaging outcomes. It is hoped that these data will be helpful in anticipating the disease course and in planning clinical trials for MELAS.

Evaluation with three-dimensional computed tomography after anterior skull base reconstruction using two musculopericranial flaps and a grafted bone

Postoperative evaluation by three-dimensional (3D) computed tomography (CT) was performed in 15 patients who underwent anterior skull base reconstruction using two musculopericranial flaps and a grafted bone sandwiched between the two flaps. Especially in the case of large bone grafts (4 x 4 cm or more), the graft was positioned with the convex side facing upward into the cranial cavity to avoid creating an intracranial dead space. The extent of the absorption and changes in the contour of the grafted bone were evaluated. Imaging was done at a CT level of 150 using a Proceed 3-D CT scanner (Yokogawa Medical Co., Tokyo, Japan). Donor bone for grafting to the skull base was harvested the cranium in 10 patients and the ilium in 5 others. Patients ranged in age from 7 to 76 years (mean, 47); there were 10 men and 5 women. The grafted bone ranged in size from 1 x 2 cm to 5 x 8 cm (1 x 2 cm to about 4 x 3 cm: 10 patients; 4 x 4 to about 5 x 8 cm: 5 patients).No marked absorption of grafted bone was seen in these 15 patients, and no brain hernia occurred. In patients with large bone grafts (4 x 4 cm to about 5 x 8 cm), a graft that had been positioned with the convex side facing upward into cranial cavity at the time of transplant was subsequently observed to be transformed into a downward convex contour of normal skull base. Fostoperative infection did not occur because of the dead space nor were there any symptom of pressure on the brain because of the upward convexity of the grafted bone.The present reconstructive method is not only a minimum invasive but also a safe and reliable method for anterior skull base surgery.

Effects of the systemic administration of alendronate on bone formation in a porous hydroxyapatite/collagen composite and resorption by osteoclasts in a bone defect model in rabbits

Several bisphosphonates are now available for the treatment of osteoporosis. Porous hydroxyapatite/collagen (HA/Col) composite is an osteoconductive bone substitute which is resorbed by osteoclasts. The effects of the bisphosphonate alendronate on the formation of bone in porous HA/Col and its resorption by osteoclasts were evaluated using a rabbit model. Porous HA/Col cylinders measuring 6 mm in diameter and 8 mm in length, with a pore size of 100 μm to 500 μm and 95% porosity, were inserted into a defect produced in the lateral femoral condyles of 72 rabbits. The rabbits were divided into four groups based on the protocol of alendronate administration: the control group did not receive any alendronate, the pre group had alendronate treatment for three weeks prior to the implantation of the HA/Col, the post group had alendronate treatment following implantation until euthanasia, and the pre+post group had continuous alendronate treatment from three weeks prior to surgery until euthanasia. All rabbits were injected intravenously with either saline or alendronate (7.5 μg/kg) once a week. Each group had 18 rabbits, six in each group being killed at three, six and 12 weeks post-operatively. Alendronate administration suppressed the resorption of the implants. Additionally, the mineral densities of newly formed bone in the alendronate-treated groups were lower than those in the control group at 12 weeks post-operatively. Interestingly, the number of osteoclasts attached to the implant correlated with the extent of bone formation at three weeks. In conclusion, the systemic administration of alendronate in our rabbit model at a dose-for-weight equivalent to the clinical dose used in the treatment of osteoporosis in Japan affected the mineral density and remodelling of bone tissue in implanted porous HA/Col composites.