Polyethylene glycol has immunoprotective effects on sciatic allografts, but behavioral recovery and graft tolerance require neurorrhaphy and axonal fusion

Behavioral recovery using(viable)peripheral nerve allografts to repair ablation-type(segmental-loss)peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration.Furthermore,such peripheral nerve allografts undergo immunological rejection by the host immune system.In contrast,peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks,reduced immune responses,and many axons do not undergo Wallerian degeneration.The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study.We hypothesized that polyethylene glycol might have some immune-protective effects,but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery.We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion.Ablation-type sciatic nerve injuries in outbred Sprague–Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts,but peripheral nerve allografts were loose-sutured(loose-sutured polyethylene glycol)with an intentional gap of 1–2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons.Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts,animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively.Other morphological signs of rejection,such as collapsed Schwann cell basal lamina tubes,were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively.Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts.While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts,loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively.MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts,but MHCII expression was modestly lower compared to negative control at 21 days postoperatively.We conclude that,while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts,successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts,and produce recovery of sensory/motor functions and voluntary behaviors.Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.

Polyethylene glycol fusion repair of severed rat sciatic nerves reestablishes axonal continuity and reorganizes sensory terminal fields in the spinal cord

Peripheral nerve injuries result in the rapid degeneration of distal nerve segments and immediate loss of motor and sensory functions;behavioral recovery is typically poor.We used a plasmalemmal fusogen,polyethylene glycol(PEG),to immediately fuse closely apposed open ends of severed proximal and distal axons in rat sciatic nerves.We have previously reported that sciatic nerve axons repaired by PEG-fusion do not undergo Wallerian degeneration,and PEG-fused animals exhibit rapid(within 2–6 weeks)and extensive locomotor recovery.Furthermore,our previous report showed that PEG-fusion of severed sciatic motor axons was non-specific,i.e.,spinal motoneurons in PEG-fused animals were found to project to appropriate as well as inappropriate target muscles.In this study,we examined the consequences of PEG-fusion for sensory axons of the sciatic nerve.Young adult male and female rats(Sprague–Dawley)received either a unilateral single cut or ablation injury to the sciatic nerve and subsequent repair with or without(Negative Control)the application of PEG.Compound action potentials recorded immediately after PEG-fusion repair confirmed conduction across the injury site.The success of PEG-fusion was confirmed through Sciatic Functional Index testing with PEG-fused animals showing improvement in locomotor function beginning at 35 days postoperatively.At 2–42 days postoperatively,we anterogradely labeled sensory afferents from the dorsal aspect of the hindpaw following bilateral intradermal injection of wheat germ agglutinin conjugated horseradish peroxidase.PEG-fusion repair reestablished axonal continuity.Compared to unoperated animals,labeled sensory afferents ipsilateral to the injury in PEG-fused animals were found in the appropriate area of the dorsal horn,as well as inappropriate mediolateral and rostrocaudal areas.Unexpectedly,despite having intact peripheral nerves,similar reorganizations of labeled sensory afferents were also observed contralateral to the injury and repair.This central reorganization may contribute to the improved behavioral recovery seen after PEG-fusion repair,supporting the use of this novel repair methodology over currently available treatments.

Gas Exchange, Xylem Ions and Abscisic Acid Response to Na^+-Salts and Cl^--Salts in Populus euphratica

We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.

Effectiveness of outpatient percutaneous endoscopic gastrostomy replacement using esophagogastroduodenoscopy and propofol sedation

AIM: To evaluate the effectiveness of outpatient percutaneous endoscopic gastrostomy (PEG) replacement using esophagogastroduodenoscopy (EGD) and propofol sedation. METHODS: We retrospectively assessed the outcome and complications of consecutive patients referred for PEG replacement which was performed using EGD under propofol sedation in the outpatient setting. The success rate, the mean dose of propofol, procedure time, EGD findings, discharge time from endoscopy unit, respiratory depression, and complications within 72 h of the procedure were evaluated. In a subset of these patients, the blood concentrations of propofol were measured. RESULTS: All 221 patients underwent successful PEG replacement. The mean dose of propofol was 34 mg (range, 20-60 mg) with a mean procedure time of 5.9 min (range, 3-8 min). Reflux esophagitis (12 patients), gastric ulcer (5), gastric neoplasm (2), and duodenal ulcer (1) were newly diagnosed at replacement. Discharge from endoscopy unit was possible in 100% of patients 45 min after the procedure. Only 3.6% (8) required transient supplemental oxygen. No complications occurred within 72 h of the procedure. During EGD the level of sedation and propofol blood concentrations after administration of propofol (30 mg) in these PEG patients corresponded to those of propofol (60 mg) in middle aged subjects (control). CONCLUSION: PEG replacement using EGD and propofol sedationin the outpatient setting was safe and practical.

Application and implications of polyethylene glycol-fusion as a novel technology to repair injured spinal cords

Conventional vs. polyethylene glycol （PEG）-fusion tech- nologies to repair severed spinal axons： Most spinal cord injuries （SCIs） involve cutor crush-severance of spinal tract axons in the central nervous system （CNS）. Clinical out- comes after CNS axonal severance is very poor because proximal segments of CNS axons lack a suitable environment for outgrowth （Kakulas, 1999; Fitch and Silver, 2008; Rowland et al., 2008; Kwon et al., 2010） and therefore do not naturally regenerate （Ramon y Caial, 1928）. Current strategies to try to increase behavioral recovery after SCI are focused on en- hancing the environment for axonal outgrowth.

Retrospective study of the associations between hepatitis C virus infection and metabolic factors

AIMTo evaluate the bidirectional association between metabolic syndrome (MS) components and antiviral treatment response for chronic hepatitis C virus (HCV) infection. METHODSThis retrospective cohort study included 119 HCV + patients treated with pegylated-interferon-α and ribavirin. Metabolic characteristics and laboratory data were collected from medical records. Differences in baseline clinical and demographic risk factors between responders and non-responders were assessed using independent samples t-tests or χ2 tests. The effects of sustained viral response (SVR) to antiviral treatment on de novo impairments in MS components, including impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM), were assessed using univariable and multivariable logistic regression analysis, while the effect of MS components on SVR was assessed using univariable logistic regression analysis. RESULTSOf the 119 patients, 80 (67%) developed SVR over the average 54 ± 13 mo follow-up. The cumulative risks for de novo T2DM and IFG were 5.07- (95%CI: 1.261-20.4, P = 0.022) and 3.87-fold higher (95%CI: 1.484-10.15, P = 0.006), respectively for non-responders than responders, when adjusted for the baseline risk factors age, sex, HCV genotype, high viral load, and steatosis. Post-treatment triglyceride levels were significantly lower in non-responders than in responders (OR = 0.27; 95%CI: 0.069-0.962, P = 0.044). Age and HCV genotype 3 were significantly different between responders and non-responders, and MS components were not significantly associated with SVR. Steatosis tended to attenuate SVR (OR = 0.596; 95%CI: 0.331-1.073, P = 0.08). CONCLUSIONSVR was associated with lower de novo T2DM and IFG incidence and higher triglyceride levels. Patients infected with HCV should undergo T2DM screening and antidiabetic treatment.

Heterobifunctional PEG-grafted black phosphorus quantum dots: “Three-in-One”nano-platforms for mitochondria-targeted photothermal cancer therapy

Black phosphorus(BP)nano-materials,especially BP quantum dots(BPQDs),performs outstanding photothermal antitumor effects,excellent biocompatibility and biodegradability.However,there are several challenges to overcome before offering real benefits,such as poor stability,poor dispersibility as well as difficulty in tailoring other functions.Here,a“three-in-one”mitochondria-targeted BP nano-platform,called as BPQD-PEG-TPP,was designed.In this nano-platform,BPQDs were covalently grafted with a heterobifunctional PEG,in which one end was an aryl diazo group capable of reacting with BPQDs to form a covalent bond and the other end was a mitochondria-targeted triphenylphosphine(TPP)group.In addition to its excellent near-infrared photothermal properties,BPQD-PEG-TPP had much enhanced stability and dispersibility under physiological conditions,efficient mitochondria targeting and promoted ROS production through a photothermal effect.Both in vitro and in vivo experiments demonstrated that BPQD-PEG-TPP performed much superior photothermal cytotoxicity than BPQDs and BPQD-PEG as the mitochondria targeted PTT.Thus this“three-in-one”nanoplatform fabricated through polymer grafting,with excellent stability,dispersibility and negligible side effects,might be a promising strategy for mitochondria-targeted photothermal cancer therapy.

Effects of NaCl and Iso-Osmotic Polyethylene Glycol Stress on Na^+/H^+Antiport Activity of Three Malus species with Different Salt Tolerance

Salt stress contains osmotic and ionic stress, while iso-osmotic polyethylene glycol （PEG） has only osmotic stress. This study aimed to compare the different effects on the activity of H＋-ATPase, proton pump and Na＋/H＋antiport in Malus seedlings between osmotic and ionic stress. Species of salt tolerant Malus zumi, middle salt tolerant Malus xiaojinensis and salt sensitive Malus baccata were used as experimental materials. Malus seedlings were treated with NaCl and iso-osmotic PEG stress. The activity of H＋-ATPase, proton pump and Na＋/H＋antiport of plasmolemma and tonoplast in Malus seedlings were obviously increased under salt stress, and those in salt-tolerant species increased more. Under the same NaCl concentration, the activity of H＋-ATPase, proton pump and Na＋/H＋antiport of plasmolemma and tonoplast in salt-tolerant species were all obviously higher than those in salt-sensitive one. Higher Na＋/H＋antiport activity of plasmolemma and tonoplast in salt-tolerant species could help to extrude and compartmentalize sodium in roots under salt stress. The ascent rate of activity of H＋-ATPase, proton pump and Na＋/H＋antiport in Malus seedlings under the three salt concentration stress was all obviously higher than that under the iso-osmotic PEG stress. It indicated that the sodium ion effect had more stimulation on the activity of H＋-ATPase, proton pump and Na＋/H＋antiport in salt-tolerant species, and salt-tolerant species has higher capability of sodium extrusion and compartmentalization in roots and is therefore more salt tolerant.

Effects of Abscisic Acid on Drought Resistance in Apple Rootstock Malus baccata Seedlings

[Objective] Abscisic acid （ABA）, a plant endogenous hormone, plays an important role in plant responses to adverse environments. This study was to explore the effects of exogenous ABA on the drought resistmlce of apple rootstocks under simulated drought condition induced by polyethylene glycol （PEG）. [Method] Apple （Malus baccata） seedlings were employed as test material. There were five treatments （T1-5） designed as ABA application rates at 0 （T1）, 25 （T2）, 50 （T3）, 75 （T4） and 100 （T5） μmol/L in the hydroponic experiments. The changes of the relative leaf water content （RLWC）, root activity, malondialdehyde （MDA） content, proline （Pro） content, superoxide dismutase （SOD） activity and peroxidase （POD） activity were assayed under PEG stress. All indices were analyzed by principal component analysis （PCA） to evaluate the optimal ABA concentration alleviating drought stress. [Result] The different concentration of ABA could increase Pro content and antioxidant enzyme activities, relieve the descent of RLWC and decrease MDA content. Low levels of ABA increased root activity, whereas the high concentrations （T3-T5） inhibited it. Statistical analysis based on the PCA indicated that the cumulative contribution rate of the first two principal components was raised to 96.457%, and the PCA in the T2 scored the highest. [Conclusion] The exogenous ABA could decrease the damage caused by drought stress to Malus baccata seedlings and enhance the ability of drought tolerance by increasing osmolyte content, anti- oxidative enzyme activity and reducing the level of membrane lipid peroxidation. The optimal concentration of ABA was 25 μmol/L.

In Vitro Screening of Cactus [Opuntia ficus-indicia (L.) Mill] Genotypes for Drought Tolerance

Drought is one of the complex environmental factors affecting growth and yield of crops in arid and semi-arid areas of the world. In this context, this investigation was carried out to select drought tolerance cactus genotypes under in vitro condition. An experiment was carried out at Laboratory of Mekelle Agricultural Research Center, Northern Ethiopia. Six cactus pear genotypes namely, Gerao, Keyih Beles, Shenkor, Limo, Lemats Beles and Suluhna were used. Areoles were used as explants in tissue culture. The non-ionic water soluble polymer polyethylene glycol (PEG) of molecular weight 6000 was used as osmoticum to simulate water stress. In the first culture, the MS medium was supplemented with (2, 4-D (4 mg/l) and BA (0.5 mg/l) for callus induction. In all cultures MS medium was supplemented with 0, 10, 20 and 40 g/l polyethylene glycol (PEG) and was solidified with 0.8% agar and 30 g of sucrose. Significant differences were observed among the genotypes, PEG levels. In the first culture highest number of explants initiated callus on medium supplemented with no PEG but had not shown significant difference with 10 g/l PEG. At 10 g/l PEG, the callus induction frequency, callus fresh weight and plantlet regeneration were recorded highest for Suluhna (83.3%, 5.5 g and 63.3%), respectively. At 40 g/l PEG, callus induction frequency, callus fresh weight and plantlet regeneration were produced highest for Suluhna (41.7%, 2.75 g and 45%), respectively but no significant difference with Gerao, Limo and Lemats Beles. However, Shenkor and Keyih Beles were induced callus but became reddish black within 35 days supplemented with 40 g/l PEG. Both shoot and root production decreased with increased PEG level in the medium. At 40 g/l PEG in MS medium, the highest shoot number was in Suluhna genotype (4.33) followed by Gerao (3.67). The highest shoot length was in Suluhna (2.11 cm) with no significant difference with Gerao (2.02 cm). Root number (5.00 and root length (1.41 cm) were in the genotype Suluhna. Survival percentage of in vitro regenerated plantlets was 100% during hardening. By taking into consideration, all the growth parameter tested revealed that Suluhna, Gerao, Limo and Lemats Beles showed better drought stress tolerance at the highest level of PEG while Keyih Beles and Shenkor appeared to be drought sensitive at the highest level of PEG.

Separation of a C_(3)H_(6)/C_(2)H_(4) mixture using Pebax^(■) 2533/PEG600 blend membranes

In industry, ethylene(C_(2)H_(4))/propylene(C_(3)H_(6)) separations are usually performed by a cryogenic process,which is energy intensive. Membrane separation technology is an alternative separation process that saves energy and is efficient. In this study, blend membranes were prepared by doping polyethylene glycol(PEG600) into a poly(ether-block-amide)(Pebax^(■) 2533) matrix and were used to separate the C_(2)H_(4)/C_(3)H_(6) mixture. The PEG 600 and Pebax^(■) 2533 polymers have good compatibility because they share hydrogen bonds. The addition of PEG600 is conducive to the hydrophilicity and the free volume of blend membranes, and it is also conducive to the solubility of C_(2)H_(4) and C_(3)H_(6) in the membranes, which improves the ability of the membranes to separate this gas pair. The Pebax^(■) 2533/PEG600 blend membrane with 15%(mass) PEG600 showed the highest separation performance in our investigated membranes, with a C_(3)H_(6)/C_(2)H_(4) selectivity of 8.9 and a C_(3)H_(6) permeability of 196 barrer(1 barrer = 1.33×10^(14)m^(3)(STP)·m·m^(-2)·s^(-1)·kPa^(-1)) at 238 K and 0.2 MPa, which is higher than that of the Pebax^(■) 2533/NaY-6%(mass) membrane(α_(C_(3)H_(6)/C_(2)H_(4)) =6.5, P_(C_(3)H_(6))=211 barrer) reported in our previous work. It is confirmed that incorporating PEG600 into the Pebax^(■) 2533 matrix to fabricate blend membranes is an efficient strategy for separating light olefins.

Polyethylene glycol-fusion retards Wallerian degeneration and rapidly restores behaviors lost after nerve severance

Some biological uses of polyethylene glycol（PEG）：The use of PEG as a membrane fusogen was first reported in 1976with the creation of cell hybrids,formed by suspending two cell lines in a 50%w/w solution of PEG in water.

Transhepatic percutaneous endoscopic gastrostomy

We describe the case of a hepatic injury after the insertion of a PEG. In a cirrhotic woman affected by a locally advanced cancer of the pharynx, the PEG tube was inserted through the edge of the left lobe of the liver. The patient was treated with a conservative approach by managing abdominal pain and the PEG was removed after 4 months without complication. Hepatic injury is a rare complication of PEG placement;in order to avoid it, PEG tube should be inserted to the left of the abdominal midline and the lower edge of the liver should be defined by palpation;in cirrhotic patients, where left hepatic lobe hyper-trophy is common, ultrasound guidance could have been appropriate.

Percutaneous Endoscopic Gastrostomy (PEG) Tube Placement in Patients with Continuous-Flow Left Ventricular Assist Devices (LVAD)

Introduction: Inadequate nutritional support after LVAD placement is known to increase postoperative infections and to decrease survival. LVAD patients with prolonged mechanical ventilation and complicated postoperative recovery requiring prolonged mechanical ventilation may require long-term tube feedings. Placement of a PEG requires knowledge of the location of the LVAD pocket and driveline to avoid device infection and injury. Methods: Between August 2008 and December 2011, 39 patients underwent HeartMate II LVAD placement in our institution. Among them, 5 patients underwent PEG tube placement for long-term nutritional support. Procedure management consisted of cessation of anticoagulation and correction of abnormal coagulation;a cardiothoracic surgeon or intensivist in the operating room to communicate with the surgeon who performed the PEG procedure;and VAD coordinator or perfusionist in the operating room to assist in monitoring the VAD. Data were retrospectively analyzed to investigate complications related to the PEG placement. Results: The studied patients consisted of 3 males and 2 females with mean age of 58 +/﹣5.0. The interval of LVAD to PEG placement was a mean 21 +/﹣8.8 days. PEG was successfully performed in the operating room in all patients. There were no LVAD device or driveline injuries related to the PEG procedure. There were no postoperative short-term or long-term PEG related complications such as acute gastric bleeding or dislodgement of the PEG tube. Conclusions: PEG placement for HeartMate II LVAD patients can be done without increasing the risk of device or intraabdominal organ injury with carefully coordinated efforts from both the mechanical support team and surgical services.

Reduced Fasting Protocol for Endoscopic Percutaneous Gastrostomy in Intubated Patients

Background: Previous studies have shown that ICU patients receive only a fraction of their calculated nutritional goals, and that cumulative caloric deficit in the ICU has been correlated with poor outcome. One reason for this underfeeding is the frequent interruption of enteral nutrition. Many ICU patients receive enteral feeding formula via a nasogastric (NG) tube. Feeding is typically held for several hours prior to procedures due to the theoretical risk of aspiration. An alternative is to continue feeding up until the procedure begins, then stop the feeding and place the NG to suction. This evacuates the contents of the stomach and minimizes the risk of aspiration, while reducing the interruption of feeding that can result in malnutrition. Methods: This study is a review of prospectively gathered data including 55 sequential patients who underwent bedside percutaneous endoscopic gastrostomy (PEG) placement in a mixed ICU under a reduced fasting protocol. This was compared with a historical cohort of 33 critically ill trauma patients who fasted for at least 8 hours prior to the procedure. Under the reduced fasting protocol, enteral feeding via NG was continued up until the time of the procedure. The NG was then placed to suction, and sedation was given. The NG was left in place until the esophagus was cannulated, then it was removed. The PEG was placed in standard fashion, and feeding was resumed via the PEG immediately following the procedure. Results: We have documented no peri-procedural vomiting or aspiration. New diagnosis of pneumonia within 3 days occurred in 2/55 of the feeding group and 4/33 of the fasting group. Overall mortality was higher for the feeding group: 13/55 vs. 1/33, however when adjusted for baseline characteristics, the difference was no longer significant. Under our protocol, the interruption of feeding averaged approximately one hour, rather than the 8 or 9 hour interruption required by standard protocols. This saved an average of approximately 700 kilocalories per patient. Conclusion: We believe that continuing feeding via NG up until the time of bedside PEG is safe and advantageous for intubated patients in the ICU. Since there was minimal gastric content, it may also be safe for other procedures.

Synthesis and Characterization of TiO₂Porous Films for Heterogeneous Photocatalysis

Heterogeneous photocatalysis is one of the advanced oxidation processes (AOP’s). These are very used nowadays for their implementation in tertiary water treatment with solar activation, with very good results. In this study, TiO2 porous films were synthesized by sol-gel method. Polyethylene glycol (PEG) 4000 was used as a templating reagent, which is oxidized at a lower temperature than TiO2. This allows the formation of a “skeleton” of porous TiO2 with increased surface area, resulting in higher photocatalytic activity. The film characterization was made with help of FE-SEM microscope, XRD diffractometer and scotch tape test. Finally, the oxidation experiments were performed using methylene blue as a model pollutant and they revealed an increase in the photocatalytic activity of porous films in comparison with the non-porous films.

Modification of Titanium Surfaces via Surface-initiated Atom Transfer Radical Polymerization to Graft PEG-RGD Polymer Brushes to Inhibit Bacterial Adhesion and Promote Osteoblast Cell Attachment

Implant-related infection is one of the key concerns in clinical medicine, so the modification of titanium to inhibit bacterial adhesion and support osteoblast cell attachment is important. In this article, two strategies were used to examine the above effects. First, modification of titanium via surface-initiated atom transfer radical polymerization（ATRP） was performed. The surface of the titanium was activated initially by a silane coupling agent. Well-defined polymer brushes of poly（ethylene glycol） methacrylate were successfully tethered on the silane-coupled titanium surface to form hydration shell to examine the anti-fouling effect. Second, functionalization of the Ti-PEG surface with RGD was performed to examine the anti-bacterial adhesion and osteoblast cell attachment ability. The chemical composition of modified titanium surfaces was characterized by X-ray photoelectron spectroscopy（XPS）. Changes in surface hydrophilicity and hydrophobicity were characterized by static water contact angle measurements. Results indicated that PEG-RGD brushes were successfully tethered on the titanium surface. And anti-bacterial adhesion ability and osteoblast cell attachment ability were confirmed by fluorescence microscopy and scanning electron microscopy. Results indicated that PEG can inhibit both bacterial adhesion and osteoblast cell attachment, while PEG-RGD brushes can not only inhibit bacterial adhesion but also promote osteoblast cell attachment.

New Approach for the Determination of Tricyclic Antidepressant Amitriptyline Using <i>β</i>-Cyclodextrin-PEG System via Spectrophotomerty

A new and simple procedure for the spectrophotometric determination of the tricyclic antidepressant drug amitriptyline is proposed. The method is based on enhancement of sensitivity of the [AMIYTP]+ β-cyclodextrin and PEG molecules involved in formation of molecules inclusion complex, in presence of polyethylene glycol (PEG) medium. The mole ratio of [AMIYTP]+ β-cyclodextrin and PEG molecules in inclusion complex were determined by the curve fitting method. The value of molar absorptivity of {[AMIYTP: (β CD)] PEG} complex in term of the drug lies in rage of (2.20 - 2.23) × 104 L·mole–1·cm–1 at absorption maximum 242 nm. The slope, intercept and correlation co-efficient were found to be 14.21, 0.0046, and 0.998, respectively. The effect of analytical variables on the determination of the drug and composition of the ion associated complex are discussed in the paper. This method is applicable in the determina-tion of amitriptyline in the pharmaceutical preparations.

PEG－mediated Gene Transfer into Orychophragmus Violaceus Cotyledon Protoplast and Regeneration of Transgenic Plants

Transgenic plants were obtained by PEG-mediated tranfer of foreign gene into cotyledon protoplasts of Orychophragums violaceus. Systematic study was carricd out on PEG-mediatcd transformation of cotyledon protoplast using transient expression system, which showed 25-30 μg of pasmid, 15% PEG and a pH value of 8.0 as the optimal parameters contributing to the highest expression level. Using these parameters, cotyledon protoplasts were isolated, treated with bacterial plasmid DNA (pBI222 with HPT as selective marker) and PEG, and cultured at a density of 5×10 4/ml.After 10-15 days,they were selected by adding 25 μg/ml hygromycine. One month later, a few calli were observed, which were then transferred onto a solid medium with 50-100 μg/ml hygromycine for proliferation. Later they were transferred successively onto differentiation and rooting media and finally hygromycineresistant whole plants were obtaincd. The plants grew well in pots and a regeneration rate of 5 ×10(-5) was achieved. Then,excised leaves of the transgenic plants were used as explants for Southern blot analysis, which confirmed the stable integration of HPT gene into the chromosomal genome of Orychophragmus violaceus The transformation frequency was 10-5.

蜂蜜在住院患者结肠镜检查前肠道准备中的应用

目的探讨蜂蜜在住院患者行结肠镜检查前肠道准备中的临床效果。方法选择2022年4月-2022年7月于该院消化科住院拟行结肠镜检查前肠道准备的患者87例,采用便利抽样法分为对照组(n=43)和观察组(n=44)。对照组采用常规方案服用复方聚乙二醇(PEG)电解质散(和爽)进行肠道准备,观察组在和爽溶液中添加20 mL蜂蜜进行肠道准备。比较两组患者肠道清洁度、和爽口感、患者不良反应、患者满意度和再次肠道准备意愿。结果两组患者肠道清洁度比较,差异无统计学意义(P>0.05)。观察组恶心、腹胀、低血糖和肛门刺激征发生率低于对照组,严重程度轻于对照组,差异均有统计学意义(P<0.05)。观察组和爽口感优于对照组,患者满意度和再次肠道准备意愿高于对照组,差异均有统计学意义(P<0.05)。结论蜂蜜可以改善和爽的口感,降低口服和爽不良反应发生率及严重程度,提高患者满意度和再次肠道准备意愿。