Dual-Centre Harmonised Multimodal Positron Emission Tomography/Computed Tomography Image Radiomic Features and Machine Learning Algorithms for Non-small Cell Lung Cancer Histopathological Subtype Phenotype Decoding

AIMS

We aimed to build radiomic models for classifying non-small cell lung cancer (NSCLC) histopathological subtypes through a dual-centre dataset and comprehensively evaluate the effect of ComBat harmonisation on the performance of single- and multimodality radiomic models.

MATERIALS AND METHODS

A public dataset of NSCLC patients from two independent centres was used. Two image fusion methods, namely guided filtering-based fusion and image fusion based on visual saliency map and weighted least square optimisation, were used. Radiomic features were extracted from each scan, including first-order, texture and moment-invariant features. Subsequently, ComBat harmonisation was applied to the extracted features from computed tomography (CT), positron emission tomography (PET) and fused images to correct the centre effect. For feature selection, least absolute shrinkage and selection operator (Lasso) and recursive feature elimination (RFE) were investigated. For machine learning, logistic regression (LR), support vector machine (SVM) and AdaBoost were evaluated for classifying NSCLC subtypes. Training and evaluation of the models were carried out in a robust framework to offset plausible errors and performance was reported using area under the curve, balanced accuracy, sensitivity and specificity before and after harmonisation. N-way ANOVA was used to assess the effect of different factors on the performance of the models.

RESULTS

Support vector machine fed with selected features by recursive feature elimination from a harmonised PET feature set achieved the highest performance (area under the curve = 0.82) in classifying NSCLC histopathological subtypes. Although the performance of the models did not significantly improve for CT images after harmonisation, the performance of PET and guided filtering-based fusion feature signatures significantly improved for almost all models. Although the selection of the image modality and feature selection methods was effective on the performance of the model (ANOVA P-values <0.001), machine learning and harmonisation did not change the performance significantly (ANOVA P-values = 0.839 and 0.292, respectively).

CONCLUSION

This study confirmed the potential of radiomic analysis on PET, CT and hybrid images for histopathological classification of NSCLC subtypes.

The effectiveness of an online video-based group schema therapy in improvement of the cognitive emotion regulation strategies in women who have undergone bariatric surgery

BACKGROUND

Adaptive cognitive emotion regulation (CER) strategies toward eating play a very important role in obesity and according to schema therapy, patients with obesity learn that don't respond to their emotional stimuli by eating. Thus, this study aimed to evaluate the effectiveness of an online video-based group schema therapy in improvement of the CER strategies and body mass index (BMI) in women who had undergone bariatric surgery.

METHODS

Forty women who had undergone sleeve gastrectomy were selected and randomly divided into two groups of control and experimental. The experimental group received 10 weekly 90-min sessions of group schema therapy, the control group did not receive any intervention at all. Both groups completed the CER strategies questionnaire during pre-test, post-test and follow-up stages, and the data were analyzed using a multivariate analysis of covariance (MANCOVA) through SPSS software (version 20).

RESULTS

Our results indicated that the experimental group demonstrated significantly higher adaptive CER strategies (P = 0.0001, F = 31.15) and significantly lower maladaptive CER strategies (P = 0.001, F = 9.42), significantly lower BMI (P = 0.001, F = 23.48), as compared to the control condition, following the group schema therapy after the follow-up stage.

CONCLUSION

The findings demonstrated that group schema therapy could lead to an increases in adaptive CER strategies and a decrease in maladaptive CER strategies and BMI in women who had undergone bariatric surgery.

TRIAL REGISTRATION

IRCT, IRCT20180523039802N2. Registered 5 August 2020, http://www.irct.com/IRCT20180523039802N2 .

Estimating the parameters of a dependent model and applying it to environmental data set

In this paper, a new dependent model is introduced. The model is motivated using the structure of series-parallel systems consisting of two series-parallel systems with a random number of parallel sub-systems that have fixed components connected in series. The dependence properties of the proposed model are studied. Two estimation methods, namely the moment method, and the maximum likelihood method are applied to estimate the parameters of the distributions of the components based on observing the system's lifetime data. A Monte Carlo simulation study is used to evaluate the performance of the estimators. Two real data sets are used to illustrate the proposed method. The results are useful for researchers and practitioners interested in analyzing bivariate data related to extreme events.

Bone Densitometry and Fat Index after Sleeve and Subsleeve Gastrectomy in Animal Model

Background

Previous studies have reported that gastrectomy and fundectomy can induce osteopenia. Body fat index is a new index of obesity that shows central obesity and other risks of obesity. Sleeve gastrectomy (SG) is a bariatric surgery and a new technique introduced as subsleeve, which only resected fundus of the stomach. In this study, it has been shown the effect of subsleeve and SG on fat index and bone densitometry in an animal model.

Materials and Methods

Rabbits were underlined SG, fundectomy (surgical removal of fundus), or sham-operated (controls without any resection), and after 12 weeks, fat index and bone densitometry were obtained.

Results

Our study showed that there was no significant difference between SG and fundectomy groups in bone mass density and fat mass after surgery in comparison with presurgery condition. SG group were associated with lower fat index and bone density, and it showed significantly decrease in weight after 1.5 months.

Conclusion

Sub-SG did not show any significant effect on fat index and bone densitometry in comparison with SG. However, we found lower fat index in sleeve group of rabbits, but it was not statistically significant.

Self-management Behaviors and Anthropometric Indices after Roux-en-Y Gastric Bypass

BACKGROUND

The aim of this study was to correlate the connection between self-management behaviors and anthropometric indices after Roux-en-Y gastric bypass (RYGB).

METHODS

A sample of 180 patients suffering from obesity were treated with RYGB in 2019; 6 and 18 months after surgery, anthropometric indices, including weight, waist circumference, waist- to-height ratio, body mass index (BMI), and waist-to-hip ratio, were gauged, and participants completed the post-bariatric surgery self-management behaviors questionnaire.

RESULTS

Correlation matrix results showed that all anthropometric indices had a significant positive relationship with self-management behaviors after RYGB; the results of the 18-month post-surgical follow-up exhibited no significant difference between anthropometric indices and self-management behaviors, 6 and 18 months after surgery.

CONCLUSION

Therefore, the more self-management behaviors increase, the greater decrease in anthropometric indices will happen after RYGB.

Self-Efficacy, Happiness and Psychological Well-Being After Sleeve Gastrectomy

PURPOSE

Sleeve gastrectomy (SG) is an effective treatment for patients with severe obesity and it leads to significant weight loss and promotes the quality of life. The aim of this study was evaluating the relationship between self-efficacy, happiness and psychological well-being after sleeve gastrectomy.

METHODS

One hundred patients that underwent SG were participated in this study. They were asked to fill questionnaires 12 months after surgery. To assess self-efficacy, Sherer and et al. scale, for happiness, oxford happiness scale and for psychological well-being, Ryff scale were used. Regression analysis was used on psychological well-being and happiness for evaluating the prediction of self-efficacy.

RESULTS

The results showed that 44% of happiness and 4% of psychological well-being were determined by self-efficacy after surgery.

CONCLUSION

Based on these findings, self-efficacy is a significant predictor of psychological well-being and happiness.

Monitoring the quality of frozen-thawed venous segments using bioimpedance spectroscopy

OBJECTIVE

Storage at temperatures as low as -80 °C and below (cryopreservation) is considered a method for long-term preservation of cells and tissues, and especially blood vessel segments, which are to be used for clinical operations such as transplantation. However, the freezing and thawing processes themselves can induce injuries to the cells and tissue by damaging the structure and consequently functionality of the cryopreserved tissue. In addition, the level of damage is dependent on the rate of cooling and warming used during the freezing-thawing process. Current methods for monitoring the viability and integrity of cells and tissues after going through the freezing-thawing cycle are usually invasive and destructive to the cells and tissues. Therefore, employing monitoring methods which are not destructive to the cryopreserved tissues, such as bioimpedance measurement techniques, is necessary. In this study we aimed to design a bioimpedance measurement setup to detect changes in venous segments after freezing-thawing cycles in a noninvasive manner.

APPROACH

A bioimpedance spectroscopy measurement technique with a two-electrode setup was employed to monitor ovine jugular vein segments after each cycle during a process of seven freezing-thawing cycles.

MAIN RESULTS

The results demonstrated changes in the impedance spectra of the measured venous segments after each freezing-thawing cycle.

SIGNIFICANCE

This indicates that bioimpedance spectroscopy has the potential to be developed into a novel method for non-invasive and non-destructive monitoring of the viability of complex tissue after cryopreservation.

Late Gastropleural Fistula after the Management of Laparoscopic Sleeve Gastrectomy Leakage

One of the rare but serious complications of laparoscopic sleeve gastrectomy (LSG) with significant morbidity and mortality is gastropleural fistula (GPF). Here, we present a 34-year-old woman who underwent LSG. Due to leakage in the proximal site of the stapler line and splenic artery erosion into the site of leakage after 1 month, splenectomy and drainage catheter insertion was done. Three months later, she presented with dyspnea, fever, and lung abscess, GPF was diagnosed, and Roux-en-Y fistulo-jejunostomy was done. After 10 days, her clinical condition improved, but the patient expired due to hemorrhagic cerebrovascular accident (CVA). Therefore, GPF along with other common complications should be seriously considered in patients developing post-LSG chronic respiratory symptoms.

Finite Element Simulation of the Impedance Response of a Vascular Segment as a Function of Changes in Electrode Configuration

Monitoring a biological tissue as a three dimensional (3D) model is of high importance. Both the measurement technique and the measuring electrode play substantial roles in providing accurate 3D measurements. Bioimpedance spectroscopy has proven to be a noninvasive method providing the possibility of monitoring a 3D construct in a real time manner. On the other hand, advances in electrode fabrication has made it possible to use flexible electrodes with different configurations, which makes 3D measurements possible. However, designing an experimental measurement set-up for monitoring a 3D construct can be costly and time consuming and would require many tissue models. Finite element modeling methods provide a simple alternative for studying the performance of the electrode and the measurement set-up before starting with the experimental measurements. Therefore, in this study we employed the COMSOL Multiphysics finite element modeling method for simulating the effects of changing the electrode configuration on the impedance spectroscopy measurements of a venous segment. For this purpose, the simulations were performed for models with different electrode configurations. The simulation results provided us with the possibility of finding the optimal electrode configuration including the geometry, number and dimensions of the electrodes, which can be later employed in the experimental measurement set-up.

Quantum transport through the edge states of zigzag phosphorene nanoribbons in presence of a single point defect: analytic Green's function method

Zigzag phosphorene nanoribbons have quasi-flat band edge modes entirely detached from bulk states. We analytically study the electronic transport through such edge states in the presence of a localized defect for semi-infinite and finite ribbon widths. Using the tight-binding model, we derive analytical expressions for the Green's function and transmission amplitude of both pristine and defective nanoribbons. We find that the transmission of ribbons with both semi-infinite and finite width is sensitive to the location of a single impurity defect with respect to the edge. By the presence of an impurity on the outermost edge site of the ribbon, the transmission through the edge channel, similar to a one-dimensional chain, strongly suppresses for the entire energy spectrum of the quasi-flat band. In contrast, the transmission of low-energy [Formula: see text] states, is robust as the impurity is moved one position far away from the edge on the same sub-lattice. The analytical calculations are also complemented by exact numerical transport computations using the Landauer approach.

The healing effect of Wharton's jelly stem cells seeded on biological scaffold in chronic skin ulcers: A randomized clinical trial

BACKGROUND

Chronic wound or nonhealing ulcer is essentially a wound that does not progress normally through the wound healing process. This study assessed the healing effect of umbilical cord Wharton's jelly stem cells seeded on biological scaffold in chronic skin ulcers.

MATERIALS AND METHODS

In a randomized clinical trial, five patients between 30 and 60 years with chronic diabetic wounds were enrolled. To cover the wounds, acellular amniotic membrane seeded with Wharton's jelly mesenchymal stem cells (WJSCs) was used for 9 days, every 3 days with a follow-up of 1 month. The percentage and time of wound healing and the size of wound were recorded for each patient.

RESULTS

In treated patients, the wound healing time and wound size significantly decreased, and after 6 and 9 days, the wound size significantly declined (P < 0.002).

CONCLUSION

As WJSCs seeded on amniotic membrane could significantly accelerate the healing effect in chronic diabetic wounds, they can be an alternative source in tissue engineering and repair of chronic ulcers.

Self-Management Behaviors in Obese Patients Undergoing Surgery Based on General and Specific Adherence Scales

BACKGROUND

Adherence has been defined as the degree to which a patient's voluntary behavior corresponds with the clinical recommendations of health care providers. The aim of this study was to predict self-management behaviors in obese patients undergoing surgery based on general and specific adherence scales.

METHODS

All obese patients who underwent bariatric surgery in Ghadir Mother and Child Hospital, Shiraz, Iran from April 2017 to September 2017 were enrolled. By using available sampling method, 201 patients with BMI above 35 (36.43±35.11) and in the age range of18-65 years (13.38±80/5) were selected. A questionnaire containing general adherence scale (GAS), specific adherence scale (SAS) and post-surgery self-management behaviors questionnaire (BSSQ) was completed by all patients.

RESULTS

The general and specific adherence scales were significant predictors for self-management behaviors after surgery, and positive relation was found for general and specific adherence scales with self-management behaviors.

CONCLUSION

Self-management behaviors regarding eating behaviors, supplements, fruits, vegetables, grains, protein and fluid intake, physical activity, dumping syndrome management have significant relationship with general and specific adherence scales. So increasing knowledge, skills, motivation, self-confidence, self-efficacy and self-monitoring of obese patients after surgery seem necessary.

Laparoscopic One-Anastomosis Gastric Bypass in a Patient with Morbid Obesity and Situs Inversus Totalis: a Case Report

BACKGROUND

Laparoscopic one-anastomosis gastric bypass is a new bariatric surgery technique for weight loss in morbid obesity. This technique has come to be associated with suitable weight loss results, low technical complications, short surgery time, low cost, short post-operational period, and low chances of injury comparisons with other bariatric surgical approaches to weight loss in morbid obesity such as sleeve and Roux-en-Y gastric bypass. To the best of our knowledge, there has been no report of such surgery in the case of situs inversus totalis concurrent with morbid obesity.

CASE PRESENTATION

The patient was a 36-year-old male suffering from morbid obesity (BMI, 56.8) along with situs inversus totalis. In spite of operational complexities due to the reversed location of abdominal and thoracic organs, the operation was performed similarly to routine subjects considering the diverse site of organs.

CONCLUSION

Given the considerable superiorities of one anastomosis gastric bypass over other bariatric surgical techniques, particularly concerning the simpler procedure, low surgical complication and short surgery time, this approach may guarantee positive outcomes in subjects with concurrent situs inversus totalis and morbid obesity.

Analgesic Effect of Valerian Root and Turnip Extracts

BACKGROUND

Medicinal plants are considered as one of the important sources of chemical substances with therapeutic effects. This study aimed to compare the analgesic effects of alcoholic extract of valerian root and turnip in rats.

METHODS

Fifty female Wistar rats weighing 190 g were divided into 5 equal groups of control (subcutaneous injection of 2.5% formalin in the right foot), sham (subcutaneous injection of 2.5% formalin+distilled water), experimental 1 (subcutaneous injection of 2.5% formalin+200 mg/kg turnip extract), experimental 2 (subcutaneous injection of 2.5% formalin 2+200 mg/kg valerian root extract) and experimental 3 (subcutaneous injection of 2.5% formalin+200 mg/kg turnip extract+200 mg/kg valerian root extract). The time duration of 0-5 and 16-60 minutes after injection of formalin were respectively considered as acute and chronic phases. Injection of distilled water and the extracts was conducted 30 minutes before assessing the analgesic effects.

RESULTS

A significant decrease in pain score in the acute phase was observed in the group received valerian root extract compared to the control group. Also, a significant reduction in pain score was noted in the acute and chronic phases of the group receiving simultaneous administration of valerian root and turnip extracts when compared to the control group.

CONCLUSION

Simultaneous use of valerian root and turnip extracts is recommended for analgesic effects in both acute and chronic phases of the pain.

Littoral Cell Angioma of the Spleen: An Additional Report of Four Cases with Emphasis on the Association with Visceral Organ Cancers

Aims and background

Littoral cell angioma (LCA) is an uncommon vascular tumor of the spleen recently described and interpreted as the tumoral counterpart of the normally present littoral cells lining the splenic sinus channels of red pulp. The diagnosis of LCA is suggested by a quite characteristic morphology and confirmed by the demonstration of a hybrid endothelial/histiocytic phenotype.

Methods

Four original and previously unreported cases of LCA are presented. All four splenic vascular tumors were investigated by light microscopy and immunohistochemistry for endothelial and histiocytic markers.

Results

All four cases were associated with visceral epithelial malignancies (colorectal adenocarcinoma in two cases, renal and pancreatic adenocarcinoma in one case each). One case was also associated with an intracranial tentorial meningioma.

Conclusions

We consider our findings as a novelty and signal the possible existence of a clinical syndrome. Five of a total of 21 previously reported cases in the literature were also described as being associated with other cancers (non-Hodgkin's lymphoma in two cases, two not further specified tumors of the liver and brain, an epithelial ovarian cancer, and a non-small cell lung cancer in one case each). Close follow-up and careful investigation in search of a second visceral neoplasm are strongly recommended in cases of LCA, but further clinical observations and more in-depth genetic and molecular studies are needed before any valid conclusions can be drawn.

Relationship between Body Image and Psychological Well-being in Patients with Morbid Obesity

BACKGROUND

Morbid obesity is rising around the world. It can cause unpleasant appearance and body image. Most of the studies have aimed to evaluate the psychopathology of overweight and obesity and paying attention to mental well-being in morbid obese individuals is rare. Therefore, this study aimed to assess the relationship between body image and psychological well-being in morbid obese patients.

METHODS

This cross-sectional study, using simple random sampling method, was done on 124 morbid obese patients who referred to obesity clinic in Shiraz from 2016 to 2017. The data were collected by body image index and psychological well-being questionnaire. Results were analyzed using descriptive statistics, Pearson correlation coefficient test, ANOVA, and Regression analysis.

RESULTS

The results showed a significant relationship between body image and psychological well-being (r=0.43) (P<0.001), and between the total score of the body image and all the subscales of psychological well-being except autonomy and purpose in life (P<0.05). There was also a significant relationship between the total score of psychological well-being and all the subscales of body image (P<0.05). However, there was no significant difference between the mean scores of the body image and those of psychological well-being in different categories of body mass index (BMI) (P>0.05).

CONCLUSION

Final results indicated that body image defects caused by obesity could lie in negative psychological well-being in all aspects. This study can promote health clinicians' knowledge in supporting of mental status of obese individuals. It is suggested that preventing and supporting intervention should be performed as effective methods for encountering and coping with psychological effects of obesity.

Applications of Bioimpedance Measurement Techniques in Tissue Engineering

Rapid development in the field of tissue engineering necessitates implementation of monitoring methods for evaluation of the viability and characteristics of the cell cultures in a real-time, non-invasive and non-destructive manner. Current monitoring techniques are mainly histological and require labeling and involve destructive tests to characterize cell cultures. Bioimpedance measurement technique which benefits from measurement of electrical properties of the biological tissues, offers a non-invasive, label-free and real-time solution for monitoring tissue engineered constructs. This review outlines the fundamentals of bioimpedance, as well as electrical properties of the biological tissues, different types of cell culture constructs and possible electrode configuration set ups for performing bioimpedance measurements on these cell cultures. In addition, various bioimpedance measurement techniques and their applications in the field of tissue engineering are discussed.

Enhanced Wound Healing after Leiomyoma Enucleation

Leiomyoma is a rare esophageal tumor that constitutes less than 1% of esophageal malignancies. It should be removed when diagnosed even if asymptomatic. This study presents two cases of esophageal leiomyoma in 38 and 62 years old men who presented with dysphagia and evaluated for diagnosis and location of related tumors. Patients were clinically examined and upper gastrointestinal endoscopy, chest computerized tomography scan, barium swallow and endoscopic ultrasonography were performed. The masses were diagnosed and both patients underwent 3-port right videothoracoscopic enucleation of esophageal leiomyoma with sleeve calibration tube (SCT) assistance. SCT was used to protrude out the mass from surrounding tissues. Also immunohistochemistry was done after mass enucleation. Two patients were operated routinely without any unpredictable events by help of SCT assistance. Mass size was 3.5×2.5×1 cm in one case and 1.5×1×0.5 cm in another patient. Positive smooth muscle antigen, desmin and ki67 and negative CD34, CD117 and S100 in both cases were obtained in immunohistochemistry. Patients were followed after surgery for 3 months and no complications were detected in none of them. Thoracoscopic enucleation of esophageal leiomyoma is a safe and feasible procedure which can decrease hospitalization and operation time. Based on our findings, the use of esophageal SCT help to detect smaller tumor without need of intra-operative endoscopy, facilitates separation of the tumor mass from both esophageal mucosal and muscular layers, and may prevent perforation. Finally, use of SCT makes the operation faster and safer.

The Effect of Lithospermum officinale, Silver Sulfadiazine and Alpha Ointments in Healing of Burn Wound Injuries in Rat

BACKGROUND

Burn is the most devastating condition in emergency medicine leading to chronic disabilities. This study aimed to compare the effect of Lithospermum officinale, silver sulfadiazine and alpha ointments on healing of burn wounds in rat.

METHODS

Ninety-five rats were divided into 5 groups. Group 1 just underwent burn injury, and groups 2-5 received alpha ointment, silver sulfadiazine (SSD), gel base and L. officinale extract, respectively. A hot plate was used for induction of a standard 3^rd degree burn wound. Burn wounds were macroscopically and microscopically evaluated on days 7^th, 14^th and 21^st after burn induction.

RESULTS

A decrease in the number of inflammatory cells was noted when L. officinale and SSD were applied while the most inflammatory response was seen after administration of alpha ointment. The number of macrophages alone decreased after burn injury, while the frequency was the most when L. officinale and alpha ointment were applied. Re-epithelialization, angiogenesis and formation of granulation tissue were the best in relation to L. officinale and alpha ointment while, the worst results belonged to burn injury group and SSD regarding granulation tissue formation. Considering histological assessment, the best results were observed for scoring of inflammation, re-epithelialization, angiogenesis, formation of granulation tissue and number of macrophage when L. officinale and alpha ointment were used after burn injury.

CONCLUSION

It can be concluded that topical application of L. officinale as a non-toxic, inexpensive and easy to produce herbal can lead to a rapid epithelialization and wound healing and these findings can be added to the literature on burn wound healing.

Association of retinol-binding protein 4 with metabolic syndrome in first-degree relatives of type 2 diabetic patients

Background:

Retinol-binding protein 4 (RBP4) is known to regulate lipid and glucose metabolism and insulin resistance. The influences of RBP4 on metabolic syndrome (MS) are still unclear. The purpose of this study is to evaluate the association between serum levels of RBP4 and MS components in first-degree relations of type 2 diabetic patients.

Materials and Methods:

This cross-sectional study was performed within the framework of the diabetes prevention project in Isfahan. This study has been conducted during 2012–2013. Seventy-eight subjects participate, with an average age of 43.20 ± 5.29 years. Weight, height, waist and hip circumferences, blood pressure (BP) of participants, fasting plasma glucose, hemoglobin A1c, total cholesterol, high-density lipoprotein cholesterol, triglyceride (TG), and serum RBP4 were measured from fasting blood sample taken from each participant after an overnight fast (12–14 h).

Results:

Systolic and diastolic BP were significantly higher in people in top median of RBP4 (11.8 ± 1.5 vs. 11.0 ± 1.2, P = 0.01 and 7.8 ± 1.0 vs. 7.3 ± 0.9, P = 0.03). Moreover, TG in people with high levels of RBP4 was higher compared with those with low levels of RBP4 (177.7 ± 97.6 vs. 138.7 ± 56.9, P = 0.02). People with low levels of RBP4 had significant greater hip circumferences (107.9 ± 7.5 vs. 104.3 ± 8.0, P = 0.04). There was no correlation between RBP4 and MS in crude model (odds ratio [OR]: 1.00, 0.95–1.05, P = 0.97). This null correlation remained after adjustment for body mass index, age, and physical activity (OR: 0.93, 0.91–1.07, P = 0.31).

Conclusion:

Although RBP4 levels were positively association with some risk factors of MS including hip circumference, TG, and systolic and diastolic BP, it does not seem to be a valuable marker for identification of the MS in the first relative degree of diabetic patients.

Synthesis of N, N-dimethyl N-ethyl Chitosan as a Carrier for Oral Delivery of Peptide Drugs

N, N-dimethyl N-ethyl chitosan (DMEC), a quanternized derivative of chitosan was synthesized based on a modified two-step method via a 22 factorial design to optimize the preparative conditions. The degree of deacetylation of the starting chitosan was determined by FTIR and NMR methods and was 95%. In the first step of the synthesis, mono-ethyl chitosan was prepared by introducing an ethyl group onto the amine group of chitosan via a Schiff base and in the next step methyl iodide was added to produce DMEC which was water soluble in a pH range of 4-8. The DMEC polymers with different degrees of quaternization were obtained and fully characterized using FTIR and 1H-NMR spectroscopic methods. Based on 1H-NMR calculations, the degree of quaternization was 52% by optimizing the two-step process.

Optimized Synthesis and Characterization of N-Triethyl Chitosan

Chitosan exhibits poor solubility at pH values above 6 which prevents its enhancing effects at drugs absorption of sites. In the present work, N-triethylated chitosan (TEC) was prepared based on a modified one-step process via a 22 factorial design to optimize the preparative conditions. TEC polymer with different degree of quaternization for pharmacological and pharmaceutical experiments was achieved. Ethyl iodide and sodium hydroxide concentrations were chosen as independent variables. The degree of deacetylation of the starting chitosan was predetermined by pH-metric titration, infrared, and NMR methods. TEC chloride was fully characterized using FTIR and 1H-NMR spectroscopies. Based on NMR calculations, a high degree of quaternization was achieved through the optimized one-step process. These highly N-triethylated chitosan chlorides were soluble in water at room temperature.