Freeze-crosslinking approach for preparing carboxymethyl cellulose nanofiber/zirconium hydrogels as fluoride adsorbents

Tough carboxymethylcellulose nanofibers (CMF)/zirconium (Zr) hydrogels were easily obtained by a freeze-crosslinking method, where Zr-containing HCl solution was added to frozen CMF sol and the mixture was allowed to thaw. The Zr content of the hydrogels increased with increasing Zr concentration in the initial HCl solution. Furthermore, the mechanical strength increased with increasing Zr content. The Young's modulus value was improved by approximately 6 times compared to the CMF hydrogel without Zr, i.e., from 4.5 kPa to 27.2 kPa. The hydrogel had a porous structure with a pore size of 133 ± 37 μm and a CMF-Zr sheet structure around the pores. The obtained CMF-Zr hydrogel exhibited high adsorptivity for fluoride. The maximum adsorption capacity (Qmax) was estimated to be 24.1 mg g-1. This simple gelation method provides useful insights for the development of easy-to-handle hydrogel-based adsorbents.

Nanocellulose hydrogels formed via crystalline transformation from cellulose I to II and subsequent freeze cross-linking reaction

We describe nanocellulose (NC) hydrogels formed from chemically unmodified NC by cellulose crystalline transformation and subsequent freeze cross-linking reaction. The freeze cross-linked NC hydrogel with macropores (~100 μm) was prepared by freezing a mixture of NC and NaOH (0.2 mol L-1), adding citric acid to the frozen mixture, and thawing it. Using NaOH and freezing together induced the crystalline transformation of NC from cellulose I to II via freeze concentration. After the crystalline transformation, cross-linking between the NC and CA in the freeze concentration layer provided a strong NC network structure, forming NC hydrogels with high mechanical strength. The structural changes in NC caused by NaOH, freezing, and freeze cross-linking on the angstrom to micrometer scale were investigated with FT-IR, SAXS, PXRD, and SEM. The freeze cross-linked NC hydrogel easily retained powder adsorbents in its inner space by mixing the NC-NaOH sol and the powder, and the hydrogel showed high removal efficiency for heavy metals. The results highlight the versatility of chemically unmodified celluloses in developing functional materials and suggest possible practical applications. This study also provides new insights into the efficient use of chemical reactions of cellulose under freezing conditions.

Plasticizer-gelatin mixed solutions as skin protection materials with flexible-film-forming capability

To demonstrate the feasibility of plasticizer-gelatin solutions as novel skin protection materials from a physical aspect, we evaluated the rheological properties of the solutions and the mechanical properties and textures of their dried sheets and films. Three types of sugars and polyols were employed as organic plasticizers and mixed with gelatin in solutions at plasticizer/gelatin weight ratios of 0.13-1.67. The plasticizers minimally affected the viscosities and gelation temperatures of the gelatin solutions, but they remarkably softened dried gelatin sheets, except for propylene glycol. Glycerol exhibited the best plasticizing effects, but the sheets obtained using glycerol showed tacky textures. Preliminary investigations on the film-forming properties of the solutions on the human skin showed that the fructose-gelatin solution at a weight ratio of 1.0 formed a flexible thin film with a texture and mechanical properties similar to those of a commercially available polyurethane-based flexible film dressing. In terms of physical properties, we conclude that the fructose-gelatin solution has potential as a skin protection material that transforms from a solution to a film on the skin.

Characterization and preliminary in vivo evaluation of a self-expandable hydrogel stent with anisotropic swelling behavior and endoscopic deliverability for use in biliary drainage

We demonstrate the potential of a novel self-expandable biliary stent comprised of poly(vinyl alcohol) (PVA) hydrogel with anisotropic swelling behavior and endoscopic deliverability in vivo, using a porcine stent model. The mechanism underlying the anisotropic swelling behavior and endoscopic deliverability (i.e., flexibility) was investigated by scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), evaluation of the water content and swelling ratio, and three-point bending tests. The in vivo experiment using a porcine stent model indicated that the tube-shaped PVA hydrogel could effectively expand the biliary tract, without disturbing bile flow. SEM and SAXS showed that PVA hydrogels prepared by drying under extension showed structural orientation along the extension axis, leading to anisotropic swelling. The water content of the PVA hydrogel was found to be crucial for maintaining flexibility as well as endoscopic deliverability. In conclusion, this study demonstrated the novel concept of using a hydrogel stent as a self-expandable biliary stent.

Fabrication of tough, anisotropic, chemical-crosslinker-free poly(vinyl alcohol) nanofibrous cryogels via electrospinning

PVA hydrogels with anisotropic structures have many biomedical applications; however, the hydrophilicity of PVA nanofibers degrades their mechanical properties, and the residual unreacted chemical crosslinkers are disadvantageous for medical use. Therefore, maintaining the stability of aqueous solutions without using crosslinkers is essential while synthesizing electrospun anisotropic PVA nanofibers. Herein, we developed a novel fabrication method for synthesizing tough, anisotropic, and chemical-crosslinker-free nanofibrous cryogels composed of poly(vinyl alcohol) (PVA) and glycerol (Gly) via electrospinning in conjunction with freeze-thawing treatment. Wide-angle X-ray diffraction, attenuated total reflection Fourier-transform infrared spectroscopy, and differential scanning calorimetry analysis revealed an enhanced crystallinity of the PVA and hydrogen bonds in the PVA/Gly nanofibers after freeze-thawing, thereby leading to improved stability of the PVA/Gly nanofiber in water. The scanning electron microscopy observation and tensile tests revealed that the addition of Gly improved both the orientation and the mechanical properties. The values of the toughness parallel and vertical to the fiber axis direction were 4.20 ± 0.63 MPa and 2.17 ± 0.27 MPa, respectively, thus revealing the anisotropy of this mechanical property. The PVA/Gly nanofibrous cryogel consisted of physically crosslinked biocompatible materials featuring toughness and mechanical anisotropy, which are favorable for medical applications including tissue engineering.

A new approach for reconstructing the 131I-spreading due to the 2011 Fukushima nuclear accident by means of measuring 129I in airborne particulate matter

To retrieve the diffusion trajectory of the ¹³¹I dispersed in the environment by the nuclear power plant accident in Fukushima in 2011, airborne particulate matter (APM) samples collected in the Tokyo metropolitan area were analyzed for their ¹²⁹I contents by means of accelerator mass spectrometry. In evaluating blank levels of chemicals and filters used for collecting APM, we established the analytical procedure for determining the ¹²⁹I activity of as low as 10^-8 Bq for a small piece of filter samples (about 0.1 cm²). Coupled with ¹³¹I data determined just after the accident, activity ratios of ¹²⁹I/¹³¹I were obtained with a mean value of 2.29 × 10^-8 (±28% of a standard deviation). This value is systematically smaller than a mean value of soil samples by 16-24% and the inventory data by 27%, suggesting that ¹²⁹I was partly lost from APM. As ¹²⁹I can be a proxy of ¹³¹I for APM, it is possible to trace how ¹³¹I in the particulate phase spread in eastern Japan and, furthermore, evaluate the internal radiation exposure due to ¹³¹I by inhalation of ¹³¹I-containing airborne particulates.

Ex vivo assessment of anchoring force of covered biflanged metal stent and covered self-expandable metal stent for interventional endoscopic ultrasound

BACKGROUND AND AIMS

Endoscopic ultrasound (EUS)-guided transmural drainage using a covered biflanged metal stent (CBFMS) and a conventional tubular biliary covered self-expandable metal stent (CSEMS) has recently been performed by EUS experts. However, appropriate traction force of the sheath to prevent the migration during stent deployment is well unknown. Herein, we assessed the anchoring force (AF) of the distal flange in CBFMSs and CSEMSs.

METHODS

The AFs of four CBFMSs (Stents AX, NG, PL, and SX) and six CSEMSs (Stents BF, BP, EG, HN, SP, and WF) were compared in an ex vivo setting. We assessed the AF produced by each stent using an EUS-guided transmural drainage model and an EUS-guided hepaticogastrostomy model consisting of sheet-shaped specimens of the stomach, gelatin gel, and gelatin tubes.

RESULTS

For CBFMSs, the maximum AF of Stent AX was significantly higher than those of Stents PL and SX (P < 0.05) in the porcine model. In the gelatin series, all stents except Stent NG showed a nearly similar AF. For CSEMSs, Stents HN, EG, BF, and WF showed gradual AF elevation in the porcine stomach. Stents SP and BP showed a lower AF than the other four stents. For the gelatin setting, the maximum AF of Stents HN, EG, and WF was higher than those of the other stents regardless of the type of specimens.

CONCLUSIONS

The significance of the AF and traction distance according to the property of various CBFMSs and CSEMSs could be elucidated using ex vivo models.

[Efficacy of combination chemotherapy with mitoxantrone, vincristine, doxifluridine and prednisolone for recurrence of breast cancer]

We treated fifteen patients with recurrent breast cancer by a combination of mitoxantrone (8 mg/m i.v., day 1), vincristine (1.2 mg/m i.v., day 1), doxifluridine (800 mg/body po, everyday) and prednisolone (30 mg/body po, day 1-7). Cycles were repeated every 3 weeks and all patients received more than 2 cycles. A response to treatment was observed in 9 of 15 evaluable patients (60.0%) with 4 complete remissions and 5 partial remissions. Eight patients were previously exposed to anthracyclines. In 5 of 7 cases with no previous chemotherapy, treatment was effective, and in 4 of 8 cases previous chemotherapy was effective. The toxicity was primarily leucopenia (86.7%), and 9 patients received G-CSF therapy. Other toxicities (alopecia, neurologic and general fatigue) were mild. Two patients with heart failure were recognized and treated with other therapy. This chemotherapy is effective for the treatment of recurrent breast cancer.

[Two patients with far advanced gastric cancer responding to combination chemotherapy with 5-FU and CDDP]

Combination chemotherapy with 5-FU and CDDP was given to two patients with far advanced gastric cancer. One patient was associated with metastases of lung, liver, pancreas and Virchow and periaortic lymph nodes, and the other was associated with metastases of periaortic lymph nodes and malignant ascitis. The regimen consisted of 5-FU 1,000 mg/m2 (day 1-5, continuous infusion) and CDDP 100 mg/m2 (day 3, 1 hr drip infusion). The interval was from the 6th to the 21st day. The response to chemotherapy showed shrinking of primary gastric lesions and metastases of liver, pancreas and periaortic lymph nodes, and disappearance of Virchow lymph nodes and malignant ascitis. Adverse reactions were thrombocytopenia (Grade 4), leukocytopenia (Grade 3), stomatitis (Grade 1, 3), vomiting (Grade 1, 2) and peripheral neuropathy (Grade 3). This therapy is thought to be effective against far advanced gastric cancer.

Effect of the combination of antiplatelet agents in man: combination of aspirin, trapidil, ticlopidine and dipyridamole

An in vitro study of how platelet aggregation would be inhibited by the combination of aspirin or ticlopidine irreversibly inhibitory to platelet aggregation and trapidil or dipyridamole reversibly inhibitory, was carried out. The measured 50% inhibition concentrations indicated that aspirin was most inhibitory to collagen-induced platelet aggregation, followed by trapidil, ticlopidine and dipyridamole in decreasing sequence of inhibition. The combination of either aspirin or ticlopidine with trapidil inhibited platelet aggregation more intensely than the combination of either agent with dipyridamole. Thus, in clinical use of aspirin or ticlopidine, it may be expected that the lower dosage of aspirin or ticlopidine with lower frequencies of side effects inhibits platelet aggregation effectively with the combination of trapidil rather than dipyridamole.

Effect of nicergoline on platelet aggregation, plasma viscosity and erythrocyte deformability in geriatric patients with cerebral infarction. Preliminary report

The effects of nicergoline (Sermion) on platelet aggregation, plasma viscosity and erythrocyte deformability were evaluated in 11 geriatric patients with cerebral infarction, 2 men and 9 women (ages 61-78, mean age 71.6). Nicergoline was given orally at a dose of 5 mg 3 times daily after meals for 8 weeks. Hematological variables were determined twice prior to the administration and at 4 and 8 weeks after the administration. The platelet aggregation in vitro was determined by the turbidimetric method and the level of circulating platelet aggregates was determined according to the method of Wu-Hoak. Erythrocyte deformability was determined according to the method based on the examination of passing erythrocytes through a filter containing pores smaller than the undeformed cells. Collagen-, arachidonic acid- and PAF-induced platelet aggregation was decreased after nicergoline administration. Erythrocyte deformability was increased and plasma viscosity was also decreased after the administration. Thus the improvement of platelet aggregation, plasma viscosity and erythrocyte deformability in cerebral infarction may prevent disturbing blood flow and may contribute to prevention of formation and progression of thrombosis and atherosclerosis in geriatric patients with cerebral infarction.

Effect of flunarizine on volume flow of the common carotid artery, peripheral hemodynamics, erythrocyte deformability and platelet function

The Ca2+ antagonist flunarizine (Flunarl) was administered to 14 patients (4 men and 10 women, 70.9 +/- 2.5 years old, mean +/- S.E.), suffering from cerebral atherosclerosis. The dose was 10 mg/day given for 8 weeks and the following results were obtained. The volume flow of the common carotid artery was increased in the 4th week after the administration, and this increase was maintained until the 8th week. Flunarizine caused improvement of peripheral hemodynamics, induced inhibition of platelet aggregation and improvement erythrocyte deformability. These results indicate that the Ca2+ entry blocker flunarizine improves cerebral and peripheral hemodynamics including microcirculation by inhibiting platelet aggregation and erythrocyte deformability.

The anti-platelet effect of niceritrol in patients with arteriosclerosis and the relationship of the lipid-lowering effect to the anti-platelet effect

A hypolipidemic agent, pentaerythritol tetranicotinate (niceritrol) yields nicotinic acid upon hydrolysis in vivo, but niceritrol is hardly soluble in distilled water, so that the effects of nicotinic acid on platelet aggregation in vitro were studied. Nicotinic acid inhibited in vitro platelet aggregation induced by ADP, collagen and adrenaline. Twenty patients (61.4 +/- 2.4 years (mean +/- S.E.)) with ischemic heart disease, cerebral infarction, transient cerebral ischemic attack and hypercholesterolemia were given niceritrol orally at 750 mg per day for 8 weeks. Significant decreases in ADP-, collagen- and adrenaline-induced platelet aggregation were observed at 4 and 8 weeks after niceritrol treatment. There was a significant correlation between the rates of changes in platelet aggregation and those in plasma total cholesterol or plasma LDL-cholesterol before treatment and 8 weeks following treatment. The results indicate that niceritrol has inhibitory effects on platelet aggregation not only caused by its direct action on platelet but mediated by its secondary action due to decrease in blood lipids.

Effect of eicosapentaenoic acid on the platelet aggregation and composition of fatty acid in man. A double blind study

Twelve volunteers (mean age, 60.7 +/- 4.2 years) were treated with placebo for the first week and then given partially purified eicosapentaenoic acid (EPA, 67% purity) at 2 g per day for 4 weeks. Significant decreases in ADP-, collagen- and adrenalin-induced platelet aggregation were observed at 2 and 4 weeks after EPA treatment, together with an increase in the plasma ratio of EPA to arachidonic acid and in platelet phospholipids. It was concluded that the administration of partially purified EPA was effective in decreasing platelet aggregation, possibly by changing the platelet ratio of EPA to arachidonic acid.