Which imaging method should be used for genicular nerve radio frequency thermocoagulation in chronic knee osteoarthritis?

This study aimed to perform genicular nerve RF neurotomy using two different imaging methods, fluoroscopy and ultrasound, and to compare the clinical effects and reliability of the two methods. Fifty patients with osteoarthritis were included in this study. Patients were randomly allocated into group 1 (fluoroscopy imaging) and group 2 (ultrasound imaging). Outcomes were measured using a pain scale (visual analog scale; VAS) and the Western Ontario and McMaster Universities (WOMAC) Index of Osteoarthritis. The application time in the ultrasound group (20.2 ± 6.4 min) was shorter than in the fluoroscopy group (25 ± 4.8 min) (p < 0.05). There was no difference in pain relief and functional status between the ultrasound and fluoroscopy groups. Decrease in VAS score and WOMAC total score in the first and third months was significant in both groups (p < 0.001). GNRFT under ultrasound guidance was easily applicable, safe and dynamic, and required no radiation to achieve the same benefit as the fluoroscopy-guided interventions.

Spatiotemporal intracellular nitric oxide signaling captured using internalized, near-infrared fluorescent carbon nanotube nanosensors.

Fluorescent nanosensor probes have suffered from limited molecular recognition and a dearth of strategies for spatial-temporal operation in cell culture. In this work, we spatially imaged the dynamics of nitric oxide (NO) signaling, important in numerous pathologies and physiological functions, using intracellular near-infrared fluorescent single-walled carbon nanotubes. The observed spatial-temporal NO signaling gradients clarify and refine the existing paradigm of NO signaling based on averaged local concentrations. This work enables the study of transient intracellular phenomena associated with signaling and therapeutics.

The use of train of four monitoring for clinical evaluation of the axillary brachial plexus block.

The axillary approach of brachial plexus anesthesia is the most commonly used technique for forearm and hand surgery. Dynamometer is known as objective test for the clinical assessment of motor block of the nerves in brachial plexus block. However, the use of this device may not always be practical in operating room. The train-of-four (TOF) test is a non-invasive peripheral nerve stimulator that shows the level of motor block of muscle relaxants. The aim of the study is to investigate the use of TOF testing as a peripheral nerve stimulator for objective clinical evaluation of motor block at axillary brachial plexus block. 44 patients were randomized according to the development of partial or complete motor in the axillary brachial plexus block. The nerves were selectively localized by nerve stimulation and ultrasound guidance. After obtaining an appropriate peripheral motor response, predetermined volumes of bupivacaine were selectively injected to the 4 nerves. Sensory, motor block levels and TOF values were measured at 10th, 20th, 30th minutes immediately after the axillary brachial plexus block. TOF values were gradually decreased and significant difference was observed between the development of a complete and partial motor block at 30th minute. TOF values were also significantly less in patients of complete sensory block than the patients of partial sensory block at 30th minute. The use of TOF monitoring may be beneficial to assess the objective clinical effect of motor block in the patients with axillary brachial plexus nerve block.

Preparation and characterization of nano-sized Pt-Ru/C catalysts and their superior catalytic activities for methanol and ethanol oxidation.

Carbon-supported PtRu nanoparticles (Ru/Pt: 0.25) were prepared by three different methods; simultaneous reduction of PtCl(4) and RuCl(3) (catalyst I) and changing the reduction order of PtCl(4) and RuCl(3) (catalysts II and III) to enhance the performance of the anodic catalysts for methanol and ethanol oxidation. Structure, microstructure and surface characterizations of all the catalysts were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of the XRD analysis showed that all catalysts had a face-centered cubic (fcc) structure with different and smaller lattice parameters than that of pure platinum, showing that the Ru incorporates into the Pt fcc structure by different ratios in all the catalysts. The typical particle sizes of all catalysts were in the range of 2-3 nm. The most active and stable catalyst for methanol and ethanol oxidation is catalyst III, in which a large amount (more than 90%) of PtRu alloy formation was observed. It has been found that this catalyst is about 8.0 and 33.4 times more active at ∼0.60 V towards the methanol and ethanol oxidation reactions, respectively, compared to the commercial Pt catalyst.

Efficiency enhancement of methanol/ethanol oxidation reactions on Pt nanoparticles prepared using a new surfactant, 1,1-dimethyl heptanethiol.

In this study, carbon-supported platinum nanoparticle catalysts were prepared using PtCl(4) and H(2)PtCl(6) as starting materials and 1-heptanethiol, 1,1-dimethyl heptanethiol, 1-hexadecanethiol and 1-octadecanethiol as surfactants. These nanoparticles can be used as catalysts for methanol and ethanol oxidation reactions in methanol and ethanol fuel cells. 1,1-Dimethyl heptanethiol was used for the first time in this type of synthesis; other surfactants were used to synthesize nanoparticles for comparison of the catalyst's performance. Cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to characterize the catalysts. It should also be stressed that AFM was employed for the first time in determining the surface topography of these catalysts. XRD, TEM and AFM height results indicate that the platinum crystallizes into a face-centered cubic structure and the surfactant plays an important role in determining the size of the platinum nanoparticles. XPS data revealed that the platinum was found in two different oxidation states, Pt(0) and Pt(IV) with a ratio of about 7.5:2.5, respectively. Electrochemical studies showed catalyst IIa to be the most active sample towards methanol/ethanol oxidation reactions (∼342 A g(-1) Pt at 0.612 V for methanol (4.6 times more active than the commercial catalyst), ∼309 A g(-1) Pt at 0.66 V for ethanol, (15.4 times more active than the commercial catalyst)).

The Effect of Spinal and General Anesthesia on Metastatic Lymph Node Flow in Bladder Cancer Surgery: A Pilot Study.

INTRODUCTION: The sympathetic regulation of contractile function of lymphatic vessels has received much attention in terms of metastasis mechanism nowadays in animal studies. The aim of the study to evaluate the effect of spinal or general anesthesia on flow in malignant lymph nodes in patients undergoing bladder tumor surgery with doppler ultrasound. METHODS: This prospective, observational, pilot study was performed on the patients (ASA II and III, aged 45-85) who scheduled for elective bladder tumor surgery under spinal or general anesthesia from July 2018 to August 2019. Patients were divided into two groups, spinal anesthesia and general anesthesia. Resistivity index, pulsatility index, peak systolic velocity and end diastolic velocity measurements were recorded preoperatively and postoperatively n the inguinal lymph nodes by doppler ultrasound. RESULTS: In the malignant lymph nodes, the pulsatility index value decreased with the spinal anesthesia (n=12) compared to the preoperative period (p = 0.002) but increased in the general anesthesia group (n=11) (p = 0.003). There was a significant difference in postoperative pulsatility index between the two groups (p = 0.0001) (cut off => 5.49, sensitivity 81.82%, specificity 91.67%). Postoperative peak systolic velocity values were significantly higher than preoperative values only in general anesthesia group (p = 0.021). CONCLUSIONS: Lymphatic flow in metastatic lymph nodes decreased by spinal anesthesia compared to general anesthesia evaluated by using doppler ultrasound in our study. Although this new mechanism is new in the reduction of lymphatic metastasis during cancer surgery, prospective randomized studies evaluating long-term recurrence and survival are warranted.

Topical heparin: a promising agent for the prevention of tracheal stenosis in airway surgery.

BACKGROUND: The protective effects of topical mitomycin-C (MMC) have been well documented for tracheal stenosis; however, to the best of our knowledge, the use of heparin as an anti-inflammatory agent to support wound healing in upper airway surgery was not studied before. The aim of this study was to investigate the efficacy of topical heparin for healing of tracheal re-implants in a rabbit's model and its resultant histological changes compared with that of MMC. METHODS: In a rabbit model (n = 21), an elliptically shaped portion of the anterior tracheal wall was excised (3-4 tracheal cartilages) under anesthesia and immersed in an isotonic saline solution containing 0.4 mg/mL (0.04%) MMC (n = 7), heparin (liquemine) 5000 U/mL (n = 7), or none (n = 7) for 2 min and then re-implanted. The follow-up period was 2 wk for all animals and then both the larynx and the trachea were excised for histological evaluation. Hematoxylin-eosin (H and E) staining was applied to the excised tissues for microscopic evaluation. RESULTS: Compared with controls, the granulation tissue formation score in MMC group (P = 0.03), and epithelial regeneration and inflammation scores in heparin group (P = 0.032 and P = 0.022, respectively) were more favorable. The fibrosis index and tracheal lumen ratio values were also more favorable in both MMC (P = 0.019 and P = 0.0028, respectively) and heparin (P = 0.023 and P = 0.0021, respectively) groups compared with controls on the 15th d. CONCLUSIONS: Topical heparin application may have favorable effects on healing of tracheal autografts in a rabbit model. We suggest that heparin therapy should be further researched for the prevention of tracheal stenosis in airway surgery.

[Operative stabilization of traumatic flail chest using a reconstruction plaque]. / Travmatik yelken gögsün rekonstrüksiyon plagi ile cerrahi stabilizasyonu.

Flail chest is the most serious form of blunt thoracic trauma that occurs as a result of fracture of three or more ribs from at least two places or sternal fractures and/or separation of costochondral junctions. Existence of life-threatening physiopathological changes almost always affects the clinical status of the patients. Typically the fractured segment moves in the interior and exterior directions during inspirations and expirations, respectively and this paradoxical motion is called as flail chest. Non-operative treatment approaches are usually preferred for the flail chest cases. However, surgery constitutes the unavoidable treatment procedure in the existence of severe chest wall deformities, unstable ventilation dynamics, lung and diaphragmatic injuries and prolonged mechanical ventilation. Here we present a case of traumatic flail chest in a patient with traumatic severe chest wall deformity treated by chest wall reconstruction with AO-ASIF [Arbeitsgemeindschaft fur Osteosynthesefragen (Association for the Study of Internal Fixation)] osteosynthesis plaque.

Effects of positioning in laparoscopic adnexal surgery on QT dispersion and heart rate variability under sevoflurane anesthesia.

PURPOSE: This study compared the intraoperative changes in the corrected QT dispersion and heart rate variability, predictors of autonomic cardiac function, in laparotomic and laparoscopic adnexal surgery. MATERIALS AND METHODS: The study was conducted on 46 American Society of Anaesthesiologists class I/II patients, aged 33-51 years, randomized to one of two groups, for elective gynecologic laparotomy or laparoscopy for a benign adnexal mass. Anesthesia was induced and maintained with sevoflurane. Corrected QT dispersion and spectral powers of heart rate variability were measured at baseline, before the induction of anesthesia, and intraoperatively during the adnexal surgery for 15 minutes. The lithotomy and Trendelenburg positions were set at 145 degrees and 30 degrees between thigh and body, respectively. Pneunoperitoneum was established at 12 mm Hg. Laparoscopic surgery was performed via one principal and two ancillary ports. Data were analyzed using the Wilcoxon and Mann-Whitney tests. RESULTS: A significant increase was observed in intraoperative standard deviation of RR interval values of heart rate variability in both groups compared to preoperative values (P < 0.05). The corrected QT dispersion and low and high frequency heart rate variability showed no significant changes between the two groups. CONCLUSION: Gynecologic laparoscopy with pneumoperitoneum in the lithotomy and Trendelenburg positions is as safe as laparatomy and seems not to deteriorate the autonomic cardiac function.

[The effect of spinal anesthesia on pulmonary function tests in old patients]. / Yasli hastalarda spinal anestezi uygulamasinin solunum fonksiyon testlerine etkisi.

Pulmonary function test (PFT) results are mainly dependent on age, sex, height, weight, pulmonary mechanics disturbances and cooperation of the subjects. The position and anesthesia type may also influence the PFT results. In this study we aimed to evaluate spirometric changes in old and young patients who performed spinal anesthesia. Fifty patients performed spinal anesthesia were randomized in two groups: Group 1 (n= 25) aged 60-85 years old and group 2 (n= 25) aged 20-59 years old. After electrocardiography, noninvasive blood pressure and peripheral oxygen saturation (SpO2) monitorization, spinal anesthesia using 0.5% hyperbaric bupivacain from L 3-4 intervertebral space was applied. Sensory block levels, hemodynamics and PFT such as forced vital capacity (FVC), forced expiratory volume/1 second (FEV(1)), peak expiratory flow (PEF), and forced expiratory flow at the 25 and 75% of the pulmonary volume (FEF(25-75)) were performed before and after spinal anesthesia in 10th, 40th and 100th minutes in supine and 30 degrees head position using hand type spirometry. Wilcoxon paired two tests statistical analysis was used to compare PFT changes of the subjects. Mean arterial blood pressure levels and spirometric measurements of FVC, FEV(1) and FEF25-75 decrease with respect to basal values in 40th minutes was significant in old patients whom spinal anesthesia was over Th6 level but in young patients the changes were not significant. PFT decrement probabilities should be taken in account in old patients supposing for spinal anesthesia and be paid attention for high level spinal blocks in risk group patients.

Usage of remifentanil and fentanyl in intravenous patient-controlled sedo-analgesia.

Our aim was to investigate the effects of patient-controlled sedo/analgesia with fentanyl or remifentanil during cataract surgery with phacoemulsification method under topical anaesthesia. The ethical committee has approved the prospective, randomized, double-blind study. ASA I-III, 120 patients underwent cataract surgery were randomly allocated to 3 groups. Fentanyl was administered in 0.7 microg/kg loading, 10 microg bolus dose with 5 minutes lockout time, remifentanil was administered 0.3 microg/kg loading, 20 microg bolus dose with 3 minutes lockout time by patient controlled analgesia (PCA) equipment. In the control group, saline solution was given without any analgesic drug. Cardiorespiratory system findings, verbal pain scale and sedation scores were recorded preoperatively and intraoperatively at the 5th, 10th, 15th, 20th and 30th minutes. Discomfort during surgery, pressing the PCA button, and complications were recorded. The verbal pain scale scores was significantly lower in the drug groups than the those in control group at the 15th minute. The sedation scores was significantly higher in the remifentanil group at the 5th minute (p=0.019) and in the fentanyl group at the 10th minute (p=0.007) than those in the control group. The number of patients pressing the PCA button was much higher in the control group than the drug groups (p<0.05). Patient comfort and surgeon satisfaction were higher in the drug groups (p<0.05). Intravenous-PCA sedo/analgesia addition to topical anaesthesia provides an advantage in sedo/analgesia, patient comfort, and surgeon satisfaction. PCA is a convenient and safe method, especially at the beginning of the operation when anxiety is intense, and during healon/lens implantation.

The protective effect of nitroglycerin on gastrointestinal and renal side effects of lornoxicam in rats.

UNLABELLED: The aim of this study is firstly, to determine the preventive effect of chronic usage of combination of nitroglycerin and lornoxicam on gastrointestinal and renal side effects and secondly, to investigate the oxidative and antioxidative effects of this combination in rats. METHODS: Thirty-seven Wistar male rats were divided into five groups for 15 days; isotonic group (n = 8, sodium chloride 0.09, Group ISO), lornoxicam group (n = 8, lornoxicam 1.3 mg/kg, Group L), nitroglycerin group (n = 6, nitroglycerin 1 mg/kg, Group NTG), lornoxicam-nitroglycerin combination group (n = 8, 1.3 mg/kg lornoxicam + 1 mg/kg nitroglycerin, Group L-NTG), and control group (n = 7, no drug was administered, Group C). Nitric oxide, malondialdehyde, reduced glutathione (GSH), catalase, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha concentrations were measured before drug injection and on fifteenth day in all blood samples. Gastrointestinal and renal biopsies were performed on fifteenth day. RESULTS: Two rats died on tenth and twelfth days in Group L. There were significant differences in Group L compared to the other groups for the lesions of stomach and kidney (p = 0.01, p = 0.028 respectively). Gastric ulceration was occurred in a rat in Group L. Malondialdehyde, TNF-alpha, and IL-6 levels decreased in NTG and L-NTG groups, whereas catalase and glutathion levels increased in NTG, L and L-NTG groups compared to control group (p < 0.05). CONCLUSION: Lornoxicam may cause gastrointestinal and renal side effects without oxidative stress. Adding nitroglycerin to lornoxicam for chronic treatment may prevent these side effects and enhance antioxidative effect compared to the use of lornoxicam alone in rats.

The effects of spinal anesthesia on QT interval in preeclamptic patients.

In this study, we measured the effects of spinal anesthesia on the corrected QT (QTc) interval in women with severe preeclampsia. Twenty-five preeclamptic (preeclamptic group) and 25 healthy pregnant women with normal arterial blood pressure and QTc interval (control group) were enrolled in this prospective, case-controlled study. Arterial blood pressure, heart rate, and QTc interval values were obtained before (baseline value) and at 5, 10, 20, 30, 60, and 120 min after initiation of spinal anesthesia. Total ephedrine dose, time elapsed until sensory block, and Apgar scores were recorded. Prior to spinal anesthesia, QTc interval values were significantly higher in the preeclamptic group (452 +/- 17.5 ms) when compared with that in controls (376 +/- 21.4 ms). Although the QTc interval shortened during spinal anesthesia when compared with baseline value in the preeclamptic group (P < 0.05), it showed no significant change in the control group. In conclusion, the QTc interval may be prolonged in severe preeclamptic patients who have hypertension and hypocalcemia. Spinal anesthesia for cesarean delivery may normalize that prolonged QTc interval due to sympathetic blockade.

The analgesic effect of nitroglycerin added to lidocaine on intravenous regional anesthesia.

We evaluated the analgesic effect of nitroglycerine (NTG) when added to lidocaine in IV regional anesthesia. Thirty patients undergoing hand surgery were randomly assigned to two groups. The control group (group C, n = 15) received a total dose of 40 mL with 3 mg/kg of lidocaine diluted with saline, and the NTG group (group NTG, n = 15) received an additional 200 mug NTG. Hemodynamic variables, tourniquet pain measured before and 1, 5, 10, 20, and 30 min after tourniquet inflation, and analgesic requirements were recorded during the operation. After the tourniquet deflation, at 1 and 30 min and 2 and 4 h, visual analog scale (VAS) score, time to first analgesic requirement, total analgesic consumption in the first 24 h after operation, and side effects were noted. Shortened sensory and motor block onset time (3.2 +/- 1.1 versus 4.5 +/- 1.2 min; P = 0.01 and 3.3 +/- 1.6 versus 5.2 +/- 1.8; P = 0.009 in group NTG and group C, respectively), prolonged sensory and motor block recovery times (6.8 +/- 1.6 versus 3.1 +/- 1.2 min P < 0.0001 and 7.3 +/- 1.3 versus 3.6 +/- 0.8 P < 0.0001 in group NTG and group C, respectively), shortened VAS scores of tourniquet pain (P = 0.023), and improved quality of anesthesia were found in group NTG (P < 0.05). VAS scores were lower in group NTG after tourniquet release and in the postoperative period (P = 0.001). First analgesic requirement time was longer in group NTG (225 +/- 74 min versus 39 +/- 33 min) than in group C (P < 0.0001). Postoperative analgesic requirements were significantly smaller in group NTG (P < 0.0001) but the side effects were similar in both groups. We conclude that the addition of NTG to lidocaine for IV regional anesthesia improves sensory and motor block, tourniquet pain, and postoperative analgesia without side effects.

Effects of sevoflurane on QT dispersion and heart rate variability.

The purpose of this study was to use estimates of corrected QT dispersion (QTcd) and heart rate variability (HRV) to assess the effects of sevoflurane, an inhalation agent used frequently in clinical practice, on autonomic cardiac function. This study was conducted prospectively and in a blind manner on 20 women between 38 and 51 y of age who were classified as American Society of Anesthesiologists stage I-II and whose treatment required total abdominal hysterectomy. Electrocardiograms were recorded by 12-lead Holter monitor for 5 min before sevoflurane induction and again for 5 min at 10 min after tracheal intubation. Data on the first recording were considered as baseline; those on the second recording were viewed as final data. The study was terminated at this point, and surgery was allowed to proceed. QTcd and HRV values were assessed by a cardiologist, who was blinded to all data. All parameters were expressed as a mean value +/- standard deviation. Wilcoxon's test was used to compare baseline and final data. Statistical significance was considered as P<.05. No significant changes were observed between baseline and final QTcd values and between low- and high-frequency components (LF and HF) of HRV; nor were changes seen in the LF/HF ratio. With the patient under sevoflurane/ nitrous oxide anesthesia, no significant changes were detected in QTcd, LF, and HF values, and in the LF/HF ratio, whereas a significant increase (P=.001) was seen in standard deviation of the R-R interval, which was used as a measure of cardiac autonomic tone.

[The effects of combination of two lornoxicam doses and nitroglycerine on acute pain in rats]. / Lornoksikamin 2 farkli dozunun nitrogliserinle kombinasyonunun siçanlarda akut agri üzerine etkisi.

Transdermal nitroglycerine can improve analgesic effects when used with other analgesics. The aim of the study was to investigate the additive effects of nitroglycerine combined with lornoxicam for acute pain in rats. Thirty-nine Wistar male rats were divided into five groups; Group SF (n=8, saline), Group L-1 (n=8, lornoxicam 1.3 mg/kg), Group L-2 (n=8, lornoxicam 2.6 mg/kg), Group LNO (n=8, nitroglycerine and lornoxicam, 1 mg/kg+1.3 mg/kg), and Group LNO-2 (n=8, nitroglycerine and lornoxicam, 1 mg/ kg+2.6 mg/kg). Tail flick and hot plate tests were measured in all groups before the intraperitoneal injections of drug and 30, 60 and 90 minutes after the injections. Cut-off time was 20 s and 60 s in tail-flick and hot-plate tests. Although there were significant differences between the groups according to hot-plate test at the 30th, 60th and 90th minutes (p<0.05), there was no difference between the groups with tail flick test. The most increasing of latency response in hot-plate assays was seen in Group LNO-1 compared to other groups at the 30th minute (p<0.05). The latency response increased significantly in Group L-1, L-2, LNO-1 and LNO-2 compared with saline group at the 60th and 90th minutes (p<0.05). There were significant differences in latency responses in Group L-1 and Group LNO-1 compared to Group L-2 and Group LNO-2 at the 60th and 90th minutes. In conclusion, 1.3 mg/kg dose of lornoksicam with the use of nitrogliserine provided early and efficient analgesia, but the increasing dose of lornoksicam did not maintain better analgesia.

Excess thermopower and the theory of thermopower waves.

Self-propagating exothermic chemical reactions can generate electrical pulses when guided along a conductive conduit such as a carbon nanotube. However, these thermopower waves are not described by an existing theory to explain the origin of power generation or why its magnitude exceeds the predictions of the Seebeck effect. In this work, we present a quantitative theory that describes the electrical dynamics of thermopower waves, showing that they produce an excess thermopower additive to the Seebeck prediction. Using synchronized, high-speed thermal, voltage, and wave velocity measurements, we link the additional power to the chemical potential gradient created by chemical reaction (up to 100 mV for picramide and sodium azide on carbon nanotubes). This theory accounts for the waves' unipolar voltage, their ability to propagate on good thermal conductors, and their high power, which is up to 120% larger than conventional thermopower from a fiber of all-semiconducting SWNTs. These results underscore the potential to exceed conventional figures of merit for thermoelectricity and allow us to bound the maximum power and efficiency attainable for such systems.

In vivo biosensing via tissue-localizable near-infrared-fluorescent single-walled carbon nanotubes.

Single-walled carbon nanotubes are particularly attractive for biomedical applications, because they exhibit a fluorescent signal in a spectral region where there is minimal interference from biological media. Although single-walled carbon nanotubes have been used as highly sensitive detectors for various compounds, their use as in vivo biomarkers requires the simultaneous optimization of various parameters, including biocompatibility, molecular recognition, high fluorescence quantum efficiency and signal transduction. Here we show that a polyethylene glycol ligated copolymer stabilizes near-infrared-fluorescent single-walled carbon nanotubes sensors in solution, enabling intravenous injection into mice and the selective detection of local nitric oxide concentration with a detection limit of 1 µM. The half-life for liver retention is 4 h, with sensors clearing the lungs within 2 h after injection, thus avoiding a dominant route of in vivo nanotoxicology. After localization within the liver, it is possible to follow the transient inflammation using nitric oxide as a marker and signalling molecule. To this end, we also report a spatial-spectral imaging algorithm to deconvolute fluorescence intensity and spatial information from measurements. Finally, we demonstrate that alginate-encapsulated single-walled carbon nanotubes can function as implantable inflammation sensors for nitric oxide detection, with no intrinsic immune reactivity or other adverse response for more than 400 days.

Molecular recognition using corona phase complexes made of synthetic polymers adsorbed on carbon nanotubes.

Understanding molecular recognition is of fundamental importance in applications such as therapeutics, chemical catalysis and sensor design. The most common recognition motifs involve biological macromolecules such as antibodies and aptamers. The key to biorecognition consists of a unique three-dimensional structure formed by a folded and constrained bioheteropolymer that creates a binding pocket, or an interface, able to recognize a specific molecule. Here, we show that synthetic heteropolymers, once constrained onto a single-walled carbon nanotube by chemical adsorption, also form a new corona phase that exhibits highly selective recognition for specific molecules. To prove the generality of this phenomenon, we report three examples of heteropolymer-nanotube recognition complexes for riboflavin, L-thyroxine and oestradiol. In each case, the recognition was predicted using a two-dimensional thermodynamic model of surface interactions in which the dissociation constants can be tuned by perturbing the chemical structure of the heteropolymer. Moreover, these complexes can be used as new types of spatiotemporal sensors based on modulation of the carbon nanotube photoemission in the near-infrared, as we show by tracking riboflavin diffusion in murine macrophages.

The antinociceptive effects of systemic administration of tramadol, gabapentin and their combination on mice model of acute pain.

OBJECTIVES: The aim of the present study was to investigate the possible antinociceptive effects of systemic administration of tramadol and gabapentin either alone or in combination on acute pain models in mice. METHODS: After obtaining the approval of Animal Ethics Committee; 96 BALB/c albino male mice were divided into 12 groups: (I) control without injection, (II) control treated with saline, (III)-(IV) mice treated with tramadol 10 mg/kg or 30 mg/kg, (V)-(VIII) mice treated with gabapentin; 30, 100, 200, 300 mg/kg respectively. In order to determine possible interactions between tramadol gabapentin and; mice received four different combinations of tramadol + gabapentin (30+30, 30+100, 30+200 and 30+300 mg/kg) (Groups IX-XII respectively). Mice received 0.1 ml solution for every 10 g of their weight. The drug was injected into peritonea. Thirty minutes after the drug injection, tail-flick and hot-plate tests were conducted. RESULTS: Ten and 30 mg/kg tramadol produced dose dependent antinociceptive effect in tail-flick and hot plate tests. Gabapentin had no antinociceptive effect in the tail flick test except 300 mg/kg dose, and had dose dependent antinociceptive effect in hot-plate test. In both tests, various combinations of tramadol and gabapentin produced an antinociceptive effect that is greater than that produced by tramadol and gabapentin alone. But, just 30 mg/kg tramadol + 300 mg/kg gabapentin combination caused statistically significant increase in both tests (p<0.05). CONCLUSION: When gabapentin and tramadol were used in combination, gabapentin had no additive antinociceptive effect except for 300 mg/kg in tail-flick and hot-plate tests. Tail-flick test showed that tramadol produced better antinociceptive effect than gabapentin.