[Microsurgical management of petroclival meningiomas combined trans-subtemporal and suboccipital retrosigmoid keyhole approach]

OBJECTIVE

With the development of modern skull base minimally invasive technology mature and neural radio surgery techniques, it is necessary to re-examine the therapeutic strategy for the treatment of petroclival meningiomas. To sum up the operative experience and methods in microsurgical resection of petroclival meningiomas by the combining trans-subtemporal and suboccipital retrosigmoid keyhole approach. To explore the minimally invasive operation approach of petroclival meningiomas, to raise the removal degree and to improve the postoperative result using this approach.

METHODS

The clinical data of the consecutive 21 patients with the petroclival meningiomas were reviewed retrospectively. The method, degree of tumor resection,techniques of the combining keyhole approach, Karnofsky performance score (KPS) before and after operation were also analyzed. The neuronavigation guided operation was performed in 9 cases, and 12 cases were operated in the neuroelectrophysiological monitoring.

RESULTS

Total excision of the tumor resection (Simpson, I-II levels) was conducted in 18 cases (85.7%, 18/21), and 3 patients underwent close resection (Simpson III level, 14.3%, 3/21). Postoperative three-dimensional CT showed good lock bone flap restoration; Postoperative pathology confirmed meningioma. Postoperative cranial nerve dysfunction or new original nerve dysfunction were aggravated in 5 cases (23.8%) , including transient trochlear nerve (3 cases), abducent nerve (1 case), and the motor branch of trigeminal nerve paralysis (1 case). Abducent nerve paralysis (1 case) appeared, with hearing impairment. After the 3-month follow-up, 11 cases had the same KPS aspreoperation, 7 cases improved, and 3 cases not improved. The KPS score was 77.14±23.12 on average, and there was no statistically significant difference compared with that before operation (P>0.05). The postoperative follow-up for half a year showed fluent speaking and writing in 19 cases (KPS 70 or higher), and general recovery in 2 cases (KPS<70). The postoperative follow-up for 3-29 months showed no tumor recurrence or progress.

CONCLUSION

The combining trans-subtemporal and suboccipital retrosigmoid keyhole approach is simple, safe, and minimally invasive, and an ideal operation approach of petroclival meningioma. To master the operation skills and the intraoperative matters needing attention in the operation, is favorable to improve the resection rate and curative effect.

Effects of low-intensity pulsed ultrasound on spinal pseudarthrosis created by nicotine administration: a model of lumbar posterolateral pseudarthrosis in rabbits

OBJECTIVES

Low-intensity pulsed ultrasound (US) can enhance spinal fusion and fracture healing; however, its effect on spinal pseudarthrosis has not been reported in the literature. We hypothesized that low-intensity pulsed US could overcome spinal pseudarthrosis created by nicotine administration.

METHODS

Thirty-two rabbits underwent posterolateral fusion with an iliac bone graft and nicotine administration. At 5 weeks, the spines were examined by computed tomography (CT) to determine the presence of pseudarthrosis. All rabbits with pseudarthrosis were randomly divided into groups A, B, C, and D according to treatment: no second graft, iliac autograft only, low-intensity pulsed US only, and iliac autograft and low-intensity pulsed US, respectively. At 10 weeks, the rabbits were euthanized, and the specimens were assessed with radiography, CT, manual palpation, and histologic analysis.

RESULTS

One rabbit was lost because of severe infection. Twenty-seven (87%) had pseudarthrosis on CT at 5 weeks. On manual palpation at 10 weeks, the fusion rates were 0%, 29%, 0%, and 57% in groups A, B, C, and D, respectively. Group D had highest radiographic scores (mean ± SD, 2.87 ± 0.92), and the difference was statistically significant compared to the other groups (P < .001). Computed tomography confirmed that group D had the most fused segments at 10 weeks. Histologic specimens from group D also showed the most mature bone formation inside the fusion mass.

CONCLUSIONS

Low-intensity pulsed US can enhance spinal fusion but cannot overcome spinal pseudarthrosis created by nicotine administration. Stopping nicotine consumption or administering a more powerful bone substitute might be an alternative method for overcoming spinal pseudarthrosis.

Decline in intrahepatic cccDNA and increase in immune cell reactivity after 12 weeks of antiviral treatment were associated with HBeAg loss

Viral load reduction facilitates recovery of antiviral T-cell responses. Dynamic alterations in intrahepatic viraemia clearance and immune cell reactivity during the early phase of nucleoside analogue (NA) therapy and the impact of these changes on HBeAg seroconversion are unknown. Fifteen HBeAg-positive chronic hepatitis B (CHB) patients were treated with adefovir dipivoxil. T-cell reactivity to HBV core and surface antigens were tested using ELISPOT assay from baseline to week 48 post-treatment (at 4-week intervals). Before and at week 12 of treatment, paired liver biopsies were analysed for intrahepatic HBV-DNA and cccDNA via real-time fluorescent PCR. In situ detection of CD4(+) , CD8(+) T cells and NK cells was analysed by immunohistochemistry. With viral load reduction, HBV-specific IFN-γ-producing CD4(+) T cells in patients with HBeAg loss were greatly enhanced and reached the highest level at week 12, with further increase observed between week 36 and week 48. After 12 weeks of treatment, total intrahepatic HBV-DNA and cccDNA had significantly decreased; however, there was no difference in the viral loads or extent of reduction between patients with and without HBeAg loss. Paralleling reduction in viral load, intrahepatic CD8(+) T lymphocytes increased in patients with HBeAg loss compared with baseline values. Only one patient without HBeAg loss exhibited similar results. Increased immune cells were observed in certain patients along with reduced hepatic viral loads during the second phase of HBV-DNA decline, which could promote the recovery of antiviral immunity and facilitate HBeAg loss.

Surgical outcomes of degenerative lumbar spondylolisthesis with anterior vacuum disc: can the intervertebral cage overcome intradiscal vacuum phenomenon and enhance posterolateral fusion?

BACKGROUND

The vacuum phenomenon within an intervertebral disc is not an uncommon radiographic finding in the elderly. However, no reports in the English literature have focused on the effect of an anterior vacuum disc in relation to surgical outcome of same-segment spondylolisthesis. We hypothesized that instrumented posterolateral fusion is not adequate in this situation and that additional interbody fusion with cages would provide better radiographic and clinical outcomes.

METHODS

The medical records of 72 patients who underwent instrumented fusion for one-segment degenerative lumbar spondylolisthesis with a vacuum disc were reviewed. Thirty-three patients were placed in the noncage group and 39 in the cage group based on whether or not augmentation with an intervertebral cage was carried out. Radiographic parameters (disc height, translation, intradiscal angle, segmental angle, and fusion) on preoperative, postoperative, and final radiographs were compared between groups. The Oswestry Disability Index (ODI) and Brosky criteria were used to evaluate clinical outcomes.

RESULTS

Blood loss and operation time were greater in the cage group but without a significant difference (p = 0.271, p = 0.108, respectively). Preoperative radiographic data were similar between groups, but the cage group had more intradiscal lordosis, less translation, a higher disc height after surgery, and maintained these advantages at the final follow-up. In addition, the posterolateral fusion rate was significantly higher in the cage group (92.3% vs. 56.1%, p < 0.001), and they obtained more ODI improvement (30.62 vs. 26.39, p = 0.369) and a higher final satisfaction rate (79.5% vs. 57.6%, p = 0.044). There was no decrease in the incidence of developed adjacent segmental disease in the noncage group.

CONCLUSIONS

The vacuum sign at the spondylolisthesis segment should be regarded as another sign of instability. We suggest that instrumented posterolateral fusion simultaneous with intervertebral fusion with a cage can overcome this situation.

The effects of anterior vacuum disc on surgical outcomes of degenerative versus spondylolytic spondylolisthesis: at a minimum two-year follow-up

Background

The vacuum phenomenon within the intervertebral disc usually represents disc degeneration. There are no reports in the English literature that focus on the effect of an anterior vacuum disc on surgical outcome of same-segment spondylolisthesis.

Methods

Patients with degenerative spondylolisthesis (DS) or isthmic spondylolisthesis (IS) who underwent a spinal surgery between January 2005 and December 2006 were reviewed. Patients who met certain criteria, including (1) only mono-segment spondylolisthesis, (2) gas air within the disc space of the spondylolisthesis segment on preoperative radiographs, (3) having received posterior decompression, posterior pedicle screw fixation, and posterolateral fusion, and (4) at least 12 months of follow-up radiographs available to define the posterolateral fusion rate, were enrolled into the study. Four radiographic parameters (disc height, translation, intradiscal angle, segmental angle) were assessed. Two-year postoperative radiographs were used to determine whether the posterolateral segment was fused or not. Clinical outcome and complications during the follow-up period were documented.

Results

Incidence of the disc vacuum phenomenon was significantly higher in the IS group than in the DS group (p < 0.001). The IS group had more listhesis and a narrower disc height on preoperative static radiographs; however, the DS group had a more prominent angle and listhesis change in preoperative dynamic variables. The posterolateral fusion rate was significantly higher in the IS group (p = 0.019). The preoperative Oswestry Disability Index (ODI) score, the final ODI, and the ODI difference were similar between groups. More excellent and good results were seen in the IS group. Besides, better final ODI and results were seen in the bilateral fusion group than in the nonfusion group.

Conclusion

The disc vacuum phenomenon is not equal to anterior instability absolutely. Determination of stability or instability in a vacuum disc should be considered by a combination of dynamic radiographs. In the present study, vacuum discs in the DS group showed more instability and a higher posterolateral pseudoarthrosis rate.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-329) contains supplementary material, which is available to authorized users.

Chemical and physical properties of bone cement for vertebroplasty

Vertebral compression fracture is the most common complication of osteoporosis. It may result in persistent severe pain and limited mobility, and significantly impacts the quality of life. Vertebroplasty involves a percutaneous injection of bone cement into the collapsed vertebrae by fluorescent guide. The most commonly used bone cement in percutaneous vertebroplasty is based on the polymerization of methylmethacrylate monomers to polymethylmethacrylate (PMMA) polymers. However, information on the properties of bone cement is mostly published in the biomaterial sciences literature, a source with which the clinical community is generally unfamiliar. This review focuses on the chemistry of bone cement polymerization and the physical properties of PMMA. The effects of altering the portions and contents of monomer liquid and polymer powders on the setting time, polymerization temperature, and compressive strength of the cement are also discussed. This information will allow spine surgeons to manipulate bone cement characteristics for specific clinical applications and improve safety.

Degradation and dissolution of hemicelluloses during bamboo hydrothermal pretreatment

To elucidate the hemicelluloses degradation and dissolution during hydrothermal pretreatment, hemicelluloses separated from both hydrolysate and pretreated substrate were investigated. Along with the pretreatment proceeding, some hemicelluloses fractions dissolved and diffused into the bulk liquor; MW (molecular weight) of these hemicelluloses fractions increased first and then decreased as well as amount of the fractions. Based on the definition of MW of the soluble hemicellulose, it has been concluded that some insoluble hemicellulose fractions appeared in the hydrolysate. In contrast, the hemicellulose degradation occurred continually and had been observed by the gradual decrease of MW of the hemicellulose isolated from pretreated substrate. Lingering dissolution at the later stage might attribute to the facts that some soluble fractions were still entrapped in the substrate. 5-15% hemicellulose fractions remained in the pretreated substrate at the later stage were composed of soluble species.

Experimental results of a dual-beam ion source for 200 keV ion implanter

A dual beam ion source for 200 keV ion implanter aimed to produce 200 keV H2 (+) and He(+) beams simultaneously has been developed. Not suitable to use the analyzing magnet, the purity of beam extracted from the source becomes important to the performance of implanter. The performance of ion source was measured. The results of experiments show that the materials of inlet tube of ion source, the time of arc ionization in ion source, and the amount of gas flow have significant influence on the purity of beam. The measures by using copper as inlet tube material, long time of arc ionization, and increasing the inlet of gas flow could effectively reduce the impurity of beam. And the method using the gas mass flow controller to adjust the proportion of H2 (+) and He(+) is feasible.

Lignin removal and benzene-alcohol extraction effects on lignin measurements of the hydrothermal pretreated bamboo substrate

Lignin content of hydrothermal pretreated bamboo chips was determined by the two methods: TAPPI standard method (222om-06) and TAPPI standard method without benzene-alcohol extraction (BAE). The results showed that including BAE resulted in lower Klason lignin (KL) and acid soluble lignin (ASL) measurements in the prehydrolyzed substrate, that is to say, BAE removed parts of KL and ASL. Therefore, the TAPPI standard method should be modified by omitting the BAE for lignin measurements of pretreated substrate. The following lignin removal analysis suggested that lignin was removed from the bamboo substrate during pretreatment by a combination of degradation reaction and deconstruction; thereafter the pseudo lignin generated in the hydrothermal pretreatment and condensation reaction between the lignin fragments accounted for the later KL increase.

Hydrothermal pretreatment of bamboo and cellulose degradation

A systematic hydrothermal pretreatment of bamboo chips had been conducted with an aim to trace the cellulose degradation. The results showed that cellulose chain cleavage basically occurred when the temperature exceeded 150°C. A slightly higher DP (degree of polymerization) than starting material had been observed at low temperature pretreatment. Treatment at higher temperature (≥ 170°C) caused severe cleavage of cellulose and therefore gave rise to low DP with more soluble species. DP of cellulose declined drastically without additional hemicelluloses dissolution when hemicelluloses removal reached to the limit level. Cellulose degradation under hydrothermal pretreatment generally followed the zero reaction kinetics with the activity energy of 121.0 kJ/mol. Besides, the increase of cellulose crystalline index and the conversion of Iα-Iβ had also observed at the hydrothermal pretreatment.

Complications associated with instrumented lumbar surgery in patients with liver cirrhosis: a matched cohort analysis

BACKGROUND

There is no information in the English literature on the outcome of liver cirrhotic patients who have undergone instrumented lumbar surgery.

PURPOSE

To review the results of instrumented lumbar surgery in patients with liver cirrhosis and determine the surgical risk factors in this group of patients.

STUDY DESIGN

A retrospective study for comparison between two cohorts (liver cirrhosis vs. nonliver cirrhosis).

PATIENT SAMPLE

Fifty-eight patients.

OUTCOME MEASURES

Child-Turcotte-Pugh scale was used to assess the patients' hepatic functional reserve. The clinical outcomes were evaluated by the five-grade patient-centered general outcome assessment questionnaire. Any event that led to reoperation, requirement of intensive care, prolonging of the hospital stay (more than 14 days), or admission after discharge within 30 days of surgery was defined as a perioperative complication.

METHODS

Between 1997 and 2009, patients with liver cirrhosis who had undergone instrumented lumbar surgeries for degenerative lumbar disease were studied. All data were compared with those for gender-, age-, and diagnosis-matched nonliver cirrhosis patients.

RESULTS

Liver cirrhotic patients had significantly lower preoperative hemoglobin, white blood cell counts, platelets, and albumin levels and higher prothrombin time and bilirubin level. Instrumented lumbar surgery was associated with significantly more blood loss, a longer hospital stay, and more complications in patients with liver cirrhosis compared with control patients. The final satisfactory rate was higher in the control group but without statistical difference (85% vs. 65%, p=.240). In the cirrhotic group, 22 patients (76%) were Child Class A and 7 patients (24%) were Child Class B; 12 patients developed one or more complications. Patients with Child Class B had a significantly higher incidence of complications than those with Child Class A (p=.006). In patients with Child Class A, those with a score of 6 also had a significantly higher incidence of complications than those with a score of 5 (p<.001). Female gender (p=.035), a low level of albumin (p=.002), presence of ascites (p=.029), and increased blood loss (p=.044) were associated with a higher risk of complications.

CONCLUSIONS

The rate of complications after instrumented lumbar surgery was significantly higher in patients with cirrhosis than in control patients, especially in those with 6 or more Child-Turcotte-Pugh points. The surgeon should counsel these patients on the possibility of developing early complications. Several factors were associated with surgical complications and should be addressed by the spine surgeons before or when they perform these elective instrumented lumbar surgeries.

Inhibition of the sodium glucose co-transporter-2: its beneficial action and potential combination therapy for type 2 diabetes mellitus

Sodium glucose co-transporter-2 (SGLT2) inhibitors are an emerging class of glucose-lowering drugs in the management of type 2 diabetes mellitus (T2DM). In this context, SGLT2 is a low-affinity, high-capacity transporter that is expressed predominantly in the proximal renal tubules. The rationale for using SGLT2 inhibition as a drug for T2DM is derived from early evidence obtained from individuals with familial renal glycosuria, due to a SGLT2 mutation, which exhibits decreased renal tubular reabsorption of glucose in the absence of hyperglycaemia or any other signs of dysfunction. Thus, reduction of glucose reabsorption by SGLT2 inhibition represents a novel T2DM treatment approach. In light of the emerging role of SGLT2 inhibition in controlling glucose homeostasis, the current review provides a critical appraisal of the rationale, overviews of structural differences between SGLT2 inhibitors and summarizes recent preclinical and clinical studies. The physiological actions of SGLT2 inhibition in relation to insulin sensitivity, islet morphology, inflammation, body weight and blood pressure are reviewed. Finally, the safety and tolerability of SGLT2 inhibitors are also discussed in relation to their potential to provide insulin independence and enhance β-cell function, as well as their potential for synergistic/additive effects if used in combination with other antidiabetic drugs.

Surface characterizations of bamboo substrates treated by hot water extraction

Environment Scanning Electron Microscopy (ESEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface morphology and chemical changes on both the interior and exterior surface of bamboo (Dendrocalamopsis oldhami) substrates treated by hot water extraction. ESEM results showed the visible changes between exterior and interior surface of the treated substrates, in where spherical droplets did not extensively appear on both the surfaces at start of the pretreatment; nevertheless the droplets formation on the exterior surface occurred more rapidly than that of the interior surface. Results from XPS examination that the increase of C1 (C-C, C-H) concentration and decrease of O/C ratio and O1 (C=O) concentration of the samples on the both surfaces further demonstrated that both surfaces consisted of increasing amount of lignin as the extraction continued, especially for exterior surface. The O/C ratios finally reached to a level-off value with exterior surface 0.34 and interior surface 0.37.

Spark erosion: a high production rate method for producing Bi(0.5)Sb(1.5)Te3 nanoparticles with enhanced thermoelectric performance

We report a new 'spark erosion' technique for producing high-quality thermoelectric nanoparticles at a remarkably high rate and with enhanced thermoelectric properties. The technique was utilized to synthesize p-type Bi(0.5)Sb(1.5)Te(3) nanoparticles with a production rate as high as 135 g h(-1), using a relatively small laboratory apparatus and low energy consumption. The compacted nanocomposite samples made from these nanoparticles exhibit a well-defined, 20-50 nm size nanograin microstructure, and show an enhanced figure of merit, ZT, of 1.36 at 360 K. Such a technique is essential for providing inexpensive, oxidation-free nanoparticles which are required for the fabrication of high performance thermoelectric devices for power generation from waste heat, and for refrigeration.

Plasma amyloid-β oligomers level is a biomarker for Alzheimer's disease diagnosis

Amyloid beta (Aβ), especially Aβ oligomers, is important in Alzheimer's disease (AD) pathogenesis. We studied plasma Aβ(40), Aβ(42), and Aβ oligomers levels in 44 AD patients and 22 non-demented controls. Cognitive functions were assessed by Chinese version of mini-mental state examination (MMSE), Abbreviated Metal Test (AMT), Alzheimer's Disease Assessment Scale Cognitive Subscale (ADAS-cog). Plasma Aβ monomers and oligomers levels were measured by ELISA. We found that the median plasma Aβ(40) and Aβ(42) levels were similar between AD and controls, and without significant correlation with cognition. Plasma Aβ oligomers level was higher in AD than controls (642.54 ng/ml [range 103.33-2676.93] versus 444.18 ng/ml [range 150.19-1311.18], p=0.047), and negatively correlated with cognition. In multivariate logistic regression analysis, the highest tertile of Aβ oligomers levels showed an increased risk of AD than the combined group of middle and lowest tertiles (OR=8.85, p=0.013), after adjustment of gender, age and APOE4 genotype. Increased plasma Aβ oligomers level was associated with decreased MMSE and AMT scores (p=0.037, p=0.043, respectively) and increased ADAS-cog score (p=0.036), suggesting negative correlation with cognitive function. We concluded that plasma Aβ oligomers level is an useful biomarker for AD diagnosis.

Current status of vertebroplasty for osteoporotic compression fracture

Vertebral compression fracture is the most common complication of osteoporosis. It may result in persistent severe pain and limited mobility, and significantly impact the quality of life. Conservative therapy using external bracing, bed rest and analgesics is necessary for pain control in these patients. However, some patients may experience protracted or ongoing pain even with these measures. Surgical treatment is indicated when conservative treatment fails, or in patients with spinal instability or neurologic deficit. Elderly patients often have comorbilities, and because of osteoporosis, high risk of postoperative complications such as implant loosening, and further adjacent fractures. Vertebroplasty involves a percutaneous injection of bone cement into the collapsed vertebrae under fluroscopic imaging guidance. It was first reported in 1987 for the management of a painful, aggressive hemangioma of a vertebral body. Since then, vertebroplasty has been widely accepted for the treatment of vertebral osteoporotic compression fractures without neurological damage. This article summarizes the advances in vertebroplasty, and discusses the indications, technique, alternative methods, results and complications. The contents include a review of the supporting evidence to provide a comparison of the safety and efficacy of vertebroplasty and kyphoplasty.

Thousandfold change in resistivity in magnetoresistive la-ca-mn-o films

A negative isotropic magnetoresistance effect more than three orders of magnitude larger than the typical giant magnetoresistance of some superlattice films has been observed in thin oxide films of perovskite-like La(0.67)Ca(0.33)MnOx. Epitaxial films that are grown on LaAIO(3) substrates by laser ablation and suitably heat treated exhibit magnetoresistance values as high as 127,000 percent near 77 kelvin and approximately 1300 percent near room temperature. Such a phenomenon could be useful for various magnetic and electric device applications if the observed effects of material processing are optimized. Possible mechanisms for the observed effect are discussed.

Transpedicular bone grafting following short-segment posterior instrumentation for acute thoracolumbar burst fracture

Posterior short-segment instrumentation for thoracolumbar burst fracture is known for a high implant failure rate because of the lack of anterior support. Anterior body augmentation by transpedicular bone grafting has been developed as an alternative to overcome this failure. However, the efficacy of transpedicular bone grafting remains debatable. Between August 2002 and August 2006, 31 patients with a single-level thoracolumbar fracture underwent insertion of posterior short-segment pedicle screws and transpedicular bone grafting. Twenty-one men and 10 women had a mean age of 39.7 years at the time of surgery. All patients were followed up for at least 2 years; the mean follow-up period was 52.7 months. Preoperative computed tomography showed that the mean canal encroachment was 48.1%. The kyphotic angle improved from 20.9 degrees to 3.7 degrees immediately postoperatively. Loss of kyphosis correction was 2.7 degrees before implant removal and 6.2 degrees at final follow-up. The anterior body height was corrected from 50.9% to 86.9% by surgery, but collapsed to 82.2% before implant removal and became 78.1% at final follow-up. The failure of the surgery was defined as an increase of >10 degrees in local kyphosis and/or implant breakage. At last follow-up, no implants had failed, but 3 patients had a loss of correction >10 degrees ; the failure rate was 9.7%. According to the Dennis functional scales, the mean pain score was 1.7, and the mean work score was 2.2 at final follow-up. All 8 patients with partial neurological deficit initially had improvement. Analysis of the results indicated that this technique effectively corrects deformities, restores vertebral height, prevents early implant failure, and provides satisfactory clinical results.

Electrochemical Modification of Vertically Aligned Carbon Nanotube Arrays

Electrochemical oxidation and reduction were utilized to modify vertically aligned carbon nanotube (CNT) arrays grown on a porous network of conductive carbon microfibers. Ultrafast and complete CNT opening and purification were achieved through electrochemical oxidation. Highly dispersed platinum nanoparticles were then uniformly and densely deposited as electrocatalysts onto the surface of these CNTs through electrochemical reduction. Using supercritical drying techniques, we demonstrate that the unidirectionally aligned and laterally spaced geometry of the CNT arrays can be fully retained after being subjected to each step of electrochemical modification. The open-tipped CNTs can also be electrochemically detached in full lengths from the supporting substrates and harvested if needed.