Photo-responsive azobenzene interactions promote hierarchical self-assembly of collagen triple-helical peptides to various higher-order structures

Collagen is an essential structural protein in animal tissues and plays key roles in cellular modulation. We investigated methods to discover collagen model peptides (CMPs) that would self-assemble into triple helices and then grow into supramolecular organizations with diverse morphological features, which would be valuable as biomaterials. This challenging undertaking was achieved by placing azobenzene groups on the ends of the CMPs, (GPO)_n (n = 3–10), Azo-(GPO)_n. In a dilute aqueous solution (80 μM), CD spectra indicated that the Azo-(GPO)_n (n > 4) formed triple helices due to strong hydrophobic azobenzene interactions, and that helix stability was increased with the peptide segment length. The resulting triple helices induced a specific azobenzene orientation through turned and twisted configurations as shown by CD spectra. TEM observations for the same solutions disclosed the morphologies for the Azo-CMPs. Azo-(GPO)₃, having the shortest peptide segment, showed no nanostructure, both Azo-(GPO)₄ and Azo-(GPO)₅ provided consistent well-developed nanofiber structures resembling the natural collagen fibers, and Azo-(GPO)_ns (n = 6–10) grew into flexible rod-like micelle fibers. In addition, alkyl chain-attached C_mAzo-(GPO)₅ displayed a toroidal morphology, and Azp-deg-(GPO)₅ having a hydrophilic spacer assembled into a bilayer vesicle structure. These diverse morphological features are considered to be due to the characteristics of the pre-organized triple helix units. Photo-isomerization of the azobenzene moiety brought about the disappearance of such characteristic nano-architectures. When the solution concentration was increased up to 1 wt%, only Azo-(GPO)₄ and Azo-(GPO)₅ spontaneously formed hydrogels exhibiting a satisfactory gel-to-sol transition upon UV irradiation.

Collagen is an essential structural protein in animal tissues and plays key roles in cellular modulation.     

The Pitfalls in Surgical Management of Lumbar Canal Stenosis Associated with Rheumatoid Arthritis

There have been few clinical studies in the area of cervical spine that focused on surgery for treating degenerative lumbar disease in patients with rheumatoid arthritis (RA). High rates of wound complications and instrumentation failure have been reported more for RA than for non-RA patients, although clinical outcomes are similar between the two groups. Lumbar canal stenosis in RA is caused not only by degeneration but also by RA-related spondylitis, which includes facet arthritis and inflammation around the vertebral endplate. The pitfalls in surgical management of lumbar canal stenosis in RA patients are highlighted in this study. The study reviewed 12 patients with RA,who were surgically treated for lumbar canal stenosis. Two out of five patients with pulmonary fibrosis died of worsened pulmonary condition, even though there were no perioperative pulmonary complications. Two patients with pedicle screw fixation showed no instrumentation failure, but two patients with spinous process fixation needed re-operation or vertebral fracture. Surgical treatment for lumbar canal stenosis in RA patients needs to be individually adjusted. Preoperative assessments and treatments of pulmonary fibrosis and osteopenia are essential. Surgery for lumbar canal stenosis with RA should be deferred for patients with advanced pulmonary fibrosis because of its potential life-threatening risk. Fusion surgery is indicated only in patients with kyphosis or severe symptoms caused by intervertebral instability. Pedicle screw fixation with hydroxyapatite granules or sublaminar tape is recommended. Closer follow-up after surgery is necessary because of possible delayed wound infection, instrumentation failure, pathological fracture, and respiratory deterioration.     

Effects of stress‐shielding on the dynamic viscoelasticity and ordering of the collagen fibers in rabbit Achilles tendon

We investigated the effects of stress‐shielding on both viscoelastic properties and microstructure of collagen fibers in the Achilles tendon by proton double‐quantum filtered (¹H‐DQF) NMR spectroscopy. The right hind‐limbs of 20 Japanese white rabbits were immobilized for 4 weeks in a cast with the ankle in plantarflexion. Dynamic viscoelasticity of the Achilles tendons was measured using a viscoelastic spectrometer. Proton DQF NMR signals were analyzed to determine the residual dipolar coupling of bound water molecules in the Achilles tendons. Both the dynamic storage modulus (E′) and dynamic loss modulus (E″) decreased significantly in the Achilles tendons of the stress‐shielding group. The results of the ¹H‐DQF NMR examination demonstrated significantly reduced residual dipolar coupling in the Achilles tendons of this same group. The disorientation of collagen fibers by stress‐shielding should contribute to degradation of the dynamic storage and loss moduli. The alterations of the collagen fiber orientation that contributed to the function of tendinous tissue can be evaluated by performing an analysis of ¹H DQF NMR spectroscopy. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1708–1712, 2013     

Clinical Significance of Soluble Intercellular Adhesion Molecule-1 and Interleukin-6 in Patients with Extrahepatic Cholangiocarcinoma

ABSTRACT

Purpose/Aim: Although several prognostic factors for extrahepatic cholangiocarcinoma (EHC) have been reported, preoperative prognostic factors have yet to be established. We investigated the serum concentration of angiogenic, inflammatory, and nutritional parameters. Materials and Methods: Twenty-five patients with EHC were enrolled before starting treatment. Preoperative prognostic factors were identified using multivariate analyses. Results: The serum soluble intercellular adhesion molecule-1 (sICAM-1) levels were significantly higher in the patients with EHC (436.0 ± 43.2 ng/ml) than in the healthy volunteers (228.6 ± 22.0 ng/ml) (p <.001). In addition, the serum IL-6 levels were significantly higher in the patients (18.0 ± 5.6 pg/ml) than in the healthy volunteers (5.7 ± 0.8 pg/ml) (p <.05). The serum IL-6 and sICAM-1 showed a strong correlation (r = 0.559) in the patients with EHC (p <.01). The serum IL-6 (area under the curve = 0.764, p =.030, cut-off level = 11.6) and sICAM-1 (area under the curve = 0.818, p =.007, cutoff level = 322.6) were revealed to be useful as prognostic factors by the receiver operating characteristic curves. The high IL-6 group and the high sICAM-1 group showed poorer DSS than those of the respective low groups. In the multivariate analysis, IL-6 (hazard ratio: 1.050, 95% confidence interval: 1.002–1.100, p =.043) and sICAM-1 (hazard ratio: 1.009, 95% confidence interval: 1.002–1.015, p =.009) were independent prognostic factors for DSS. Conclusions: IL-6 and sICAM-1 were independent preoperative prognostic factors in EHC patients, causing continuous inflammation and malnutrition in collaboration with other pro-angiogenic factors.     

Transcatheter closure of secundum atrial septal defect

Since the introduction of transcatheter closure of atrial septal defect, device closure has become the alternative treatment of selected atrial defects. Although excellent results have been reported for transcatheter closure, concerns have arisen regarding complications, including residual shunt, systemic or pulmonary embolization of the device, and erosion and perforation of the cardiac chamber. Those complications are rare but potentially serious adverse events that may require immediate surgical intervention. This review summarizes the current trends in patient selection, result of device closure and typical complications. Comparison between transcatheter device closure and surgical closure is also made.     

Paraoxonase-1 activity affects the clopidogrel response in CYP2C19 loss-of-function carriers

Background

The impact of paraoxonase-1 (PON1) activity on the response to clopidogrel may differ in patients treated with drug-eluting stents (DES) in association with CYP2C19 loss-of-function (LOF) polymorphisms.

Methods

This study included 112 Japanese patients receiving clopidogrel (75 mg/day) and aspirin (100 mg/day) who underwent optical coherence tomography (OCT) examination 9 months after DES implantation. The CYP2C19 genotype was analyzed and LOF carriers (*1/*2, *1/*3, *2/*2, *3/*3, *2/*3) were identified. At the 9-month follow-up, platelet reactivity was determined by measuring the P2Y12 reactivity unit (PRU) using a VerifyNow P2Y12 assay, PON1 activity was evaluated and intra-stent thrombus was evaluated by OCT.

Results

Of the 112 Japanese patients, 75 were LOF carriers (67.0%). The patients were divided into tertiles according to the PON1 activity (tertile 1; < 230 U/L, tertile 2; 230–283 U/L, tertile 3; > 283 U/L). In the VerifyNowP2Y12 analysis, tertile 1 had a higher PRU than tertiles 2 and 3 in LOF carriers, and there was no difference among tertiles in non-carriers. The highest incidence of intra-stent thrombus was observed in tertile 1 followed by tertiles 2 and 3 in LOF carriers, whereas there was no such difference in non-carriers. Multivariate analysis revealed that LOF carriers and PON1 activity tertile 1 were independent predictors of intra-stent thrombus in all patients. In LOF carriers, tertile 1 was the only independent predictor for intra-stent thrombus.

Conclusion

Low PON1 activity is associated with a low response to clopidogrel and a high frequency of intra-stent thrombus only in LOF carriers.     

Hippocampal neuronal degeneration in the traumatic brain injury mouse: non-trivial effect of scalp incision

Objectives: In experimental models of traumatic brain injury (TBI), posttraumatic hippocampal neuronal degeneration in the cornu ammonis 1 (CA1), and/or the cornu ammonis 3 (CA3) regions are regarded as the most notable phenotypic appearances relating to the pathophysiology of human post-concussion syndrome. However, these morphological changes are often also seen in subjects without TBI, namely ‘sham’ groups. The frequencies and reasons of appearance of hippocampal neuronal degeneration in mice with TBI and/or sham are not clear.

Methods: We compared the frequencies of hippocampal neuronal degeneration among three groups: TBI (mice with external force impact performed by Marmarou’s weight drop model after scalp incision), sham (mice with scalp incision alone), and control (mice with neither external force impact nor scalp incision), using hematoxylin and eosin stain in day 6 (n = 5 in each group.) Isoflurane was used for anesthesia in all mice.

Results: The frequencies were 80, 100, and 20% in CA1, and 20, 40, and 60% in CA3, for TBI, sham, and control, respectively. In CA1, a significant difference of the frequency was observed between sham and control (p = 0.048), but not, between TBI and sham (p = 1.000) in Fisher’s exact test. In CA3, no significant difference in the frequency was observed between the three groups.

Conclusion: Scalp incision, rather than external impact force, might affect the CA1 hippocampal neuronal degeneration in mice with TBI. In addition, factor(s) other than external impact force or scalp incision may also cause hippocampal neuronal degeneration in both CA1 and CA3. Careful interpretation is needed concerning hippocampal neuronal degeneration induced by a weight drop device observed in mice with TBI.     

Analysis of ischemic cerebral lesions using 3.0-T diffusion-weighted imaging and magnetic resonance angiography after revascularization surgery for ischemic disease

Background

Cerebral revascularization surgery (CRS) is increasingly recognized as an important component in the treatment of complex cerebral vascular disease and tumors. CRS requires that the incidence of perioperative neurological complications should be minimized, because CRS for ischemic disease is often not the goal of treatment, but rather a prophylactic surgery. CRS carries the risk of focal postoperative neurological deficits. Little has been established concerning mechanisms of post-CRS ischemia. We used 3.0-T diffusion-weighted magnetic resonance imaging (DWI) and magnetic resonance angiography (MRA) to analyze the incidence and mechanism of ischemic lesions.

Methods

We studied the anterior circulation territory after 20 CRS procedures involving 33 vascular anastomosis procedures (13 double anastomoses and 7 single anastomoses) in 12 men and 8 women between June 2007 and October 2011. The operations included single or double superficial temporal artery–middle cerebral artery (STA–MCA) anastomosis to treat internal carotid artery/MCA occlusions or severe MCA stenosis. A combined STA–MCA anastomosis and indirect bypass were performed for moyamoya disease. Postoperative DWI and MRA were obtained in all patients between 24 and 96 h after surgery to detect thromboembolism, hypoperfusion, or procedural ischemic complications and vasospasms of the donor STA.

Results

Follow-up DWI and MRA were carried out 1.8 ± 0.6 days after CRS (range, 1–4 days). Temporary occlusion time for anastomoses averaged 18.9 min (range, 16–32 min). Asymptomatic new hyperintensities occurred in the ipsilateral hemisphere of 2 patients on postoperative DWI (10% patients/6.0% anastomoses), and 1 moyamoya patient (5.0% patients/3.0% anastomoses) developed a symptomatic hyperintensity in the ipsilateral occipital lobe in response to the operation. Two abnormal small (<5 mm) cortical DWI lesions were caused by sacrifices of a small branch of the recipient MCA.

Conclusion

This study is the first postoperative 3.0-T DWI study of CRS and related clinical events. The incidence of symptomatic postoperative DWI abnormalities was restricted to 1 moyamoya patient representing 5.0% of total patients and 3.0% anastomoses. Although some postoperative DWI abnormalities occurred, CRS was found to be safe with a low risk of symptomatic ischemia.