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In order to assess the risk of pesticides to aquatic ecosystems, five single-dose pesticides including chlorpyrifos, pymetrozine, dinotefuran, azoxystrobin, and acetochlor that are frequently used in developing countries, were selected. Based on the principle of conservative risk assessment, application amounts for different dosage forms were recommended, the Top-Rice model and risk quotient method were used to evaluate the aquatic ecological risk of the aforementioned single-dose pesticide products. The results showed that predicted peak environmental concentration ranges after application on rice were 110.52-564.25 μg/L for chlorpyrifos, 20.79-114.6 μg/L for pymetrozine, 21.81-114.02 μg/L for dinotefuran, 16.52-56.94 μg/L for azoxystrobin, and 167.22-2184.01 μg/L for acetochlor in different seasons of Changsha, Hangzhou, Nanning in China, and Lahore and Faisalabad in Pakistan. Under the current conditions of registered administration, the acute and chronic risks posed by chlorpyrifos to fish and invertebrates were deemed alarming, and those by pymetrozine and dinotefuran were considered acceptable. The acute risk of exposure of azoxystrobin to vertebrates such as fish, and invertebrates such as daphnia and shrimp is alarming, whereas the chronic risk to vertebrates, invertebrates, and algae was acceptable. The acute exposure risk posed by acetochlor was deemed worrying, and in the case of chronic exposure, only 36 % of the simulation group exhibited a risk quotient below 1, indicating no risk. These findings imply that the ecological risks of using registered chlorpyrifos and acetochlor products on rice cannot be ignored. It should be noted that the analysis method and model employed in this study were intentionally conservative to ensure a comprehensive assessment of the potential risks associated with the use of registered pesticide products. However, the model failed to consider influential factors like photolysis of pesticides on the soil surface, thereby introducing a certain degree of conservativeness in the evaluation results., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Hepatitis B virus (HBV) infection is a significant contributor to the development of hepatocellular carcinoma (HCC), a leading cause of cancer-related mortality worldwide. Iron, a central co-factor in various metabolic pathways, plays an essential role in liver function, but its dysregulation can lead to severe health consequences. Accumulation of iron within hepatic cells over time is linked to increased liver injury and is strongly associated with sensitive exposure to a range of conditions, including cirrhosis, fibrosis and ultimately, HCC. This review explores the intricate interplay between iron metabolism and HCC within the context of HBV infection. Hepatic iron overload can arise from liver injury and disruptions in iron homeostasis, causing hepatic necrosis, inflammation, and fibrosis, ultimately culminating in carcinogenesis. Moreover, alterations in serum iron components in HBV-related scenarios have been observed to impact the persistence of HBV infection. Notably, the progression of HBV-associated liver damage exhibits distinct characteristics at various stages of liver disease. In addition to elucidating the complex relationship between iron metabolism and HCC in the context of HBV infection, this review also investigates the prognostic implications of systemic iron levels for HCC. Furthermore, it aims to provide a comprehensive understanding of the intricate interplay between iron metabolism and HCC, extending the discussion to the context of hepatitis C virus (HCV) infection. By shedding light on these multifaceted connections, this review aims to contribute to our understanding of the pathogenesis of HBV-associated HCC and potentially identify novel therapeutic avenues for intervention., (© 2024 John Wiley & Sons Ltd.)

BACKGROUND End-stage hepatic alveolar echinococcosis (AE) can result in cavernous transformation of the portal vein (CTPV) due to extensive invasion of the portal vein. Ex vivo liver resection and autotransplantation (ELRA) is a new treatment option for patients with end-stage hepatic AE combined with CTPV. ELRA can achieve radical resection of HAE lesions and vascular reconstruction, and also effectively controls bleeding, particularly in cases involving multiple tortuous PV collaterals. Unfortunately, postoperative complications related to the portal vein can impede liver blood flow, thereby increasing the risk of portal hypertension and eventual failure of the transplanted liver if not promptly treated through appropriate medical interventions. CASE REPORT We report the case of a 31-year-old woman who underwent ELRA for end-stage hepatic AE combined with CTPV, and early postoperative portal vein anastomotic stenosis occurred. Stenting of the portal vein was performed after clarification of the stenotic segment by portal venography, followed by anticoagulation therapy and close ultrasound follow-up. After the operation, the patient's portal vein anastomosis widened and the blood flow into the liver returned to normal, avoiding graft liver failure. At 3-year follow-up, the portal vein stent was patent and no serious portal vein complications such as thrombosis had occurred. CONCLUSIONS ELRA provides a new therapeutic approach for patients with HAE combined with CTPV, and intraoperative portal vein reconstruction is one of the key procedures. For CTPV patients with early postoperative portal vein stenosis, interventional therapy (IVR) offers fresh perspectives and avoids acute liver failure caused by liver hypoperfusion.

Transcription factors play an essential role in pattern formation during early embryo development, generating a strikingly fast and precise transcriptional response that results in sharp gene expression boundaries. To characterize the steps leading up to transcription, we performed a side-by-side comparison of the nuclear dynamics of two morphogens, a transcriptional activator, Bicoid (Bcd), and a transcriptional repressor, Capicua (Cic), both involved in body patterning along the anterior-posterior axis of the early Drosophila embryo. We used a combination of fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and single-particle tracking to access a wide range of dynamical timescales. Despite their opposite effects on gene transcription, we find that Bcd and Cic have very similar nuclear dynamics, characterized by the coexistence of a freely diffusing monomer population with a number of oligomeric clusters, which range from low stoichiometry and high mobility clusters to larger, DNA-bound hubs. Our observations are consistent with the inclusion of both Bcd and Cic into transcriptional hubs or condensates, while putting constraints on the mechanism by which these form. These results fit in with the recent proposal that many transcription factors might share a common search strategy for target gene regulatory regions that makes use of their large unstructured regions, and may eventually help explain how the transcriptional response they elicit can be at the same time so fast and so precise., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Background: Alveolar echinococcosis (AE) primarily affects the liver and potentially spreads to other organs. Managing recurrent AE poses significant challenges, especially when it involves critical structures and multiple major organs., Case Presentation: We present a case of a 59-year-old female with recurrent AE affecting the liver, heart, and lungs following two previous hepatectomies, the hepatic lesions persisted, adhering to major veins, and imaging revealed additional diaphragmatic, cardiac, and pulmonary involvement. The ex vivo liver resection and autotransplantation (ELRA), first in human combined with right atrium (RA) reconstruction were performed utilizing cardiopulmonary bypass, and repairs of the pericardium and diaphragm. This approach aimed to offer a potentially curative solution for lesions previously considered inoperable without requiring a donor organ or immunosuppressants. The patient encountered multiple serious complications, including atrial fibrillation, deteriorated liver function, severe pulmonary infection, respiratory failure, and acute kidney injury (AKI). These complications necessitated intensive intraoperative and postoperative care, emphasizing the need for a comprehensive management strategy in such complicated high-risk surgeries., Conclusions: The multidisciplinary collaboration in this case proved effective and yielded significant therapeutic outcomes for a rare case of advanced hepatic, cardiac, and pulmonary AE. The combined approach of ELRA and RA reconstruction under extracorporeal circulation demonstrated distinct advantages of ELRA in treating complex HAE. Meanwhile, assessing diaphragm function during the perioperative period, especially in patients at high risk of developing pulmonary complications and undergoing diaphragmectomy is vital to promote optimal postoperative recovery. For multi-resistant infection, it is imperative to take all possible measures to mitigate the risk of AKI if vancomycin administration is deemed necessary., (© 2024. The Author(s).)

Membrane cholesterol-rich domains have been shown to be important for regulating a range of membrane protein activities. Low-density lipoprotein receptor (LDLR)-mediated internalization of cholesterol-rich LDL particles is tightly regulated by feedback mechanisms involving intracellular sterol sensors. Since LDLR plays a role in maintaining cellular cholesterol homeostasis, we explore the role that membrane domains may have in regulating LDLR activity. We expressed a fluorescent LDLR-mEGFP construct in HEK293T cells and imaged the unligated receptor or bound to an LDL/DiI fluorescent ligand using total internal reflection fluorescence microscopy. We studied the receptor's spatiotemporal dynamics using fluorescence fluctuation analysis methods. Image cross correlation spectroscopy reveals a lower LDL-to-LDLR binding fraction when membrane cholesterol concentrations are augmented using cholesterol esterase, and a higher binding fraction when the cells are treated with methyl-β-cyclodextrin) to lower membrane cholesterol. This suggests that LDLR's ability to metabolize LDL particles is negatively correlated to membrane cholesterol concentrations. We then tested if a change in activity is accompanied by a change in membrane localization. Image mean-square displacement analysis reveals that unligated LDLR-mEGFP and ligated LDLR-mEGFP/LDL-DiI constructs are transiently confined on the cell membrane, and the size of their confinement domains increases with augmented cholesterol concentrations. Receptor diffusion within the domains and their domain-escape probabilities decrease upon treatment with methyl-β-cyclodextrin, consistent with a change in receptor populations to more confined domains, likely clathrin-coated pits. We propose a feedback model to account for regulation of LDLR within the cell membrane: when membrane cholesterol concentrations are high, LDLR is sequestered in cholesterol-rich domains. These LDLR populations are attenuated in their efficacy to bind and internalize LDL. However, when membrane cholesterol levels drop, LDL has a higher binding affinity to its receptor and the LDLR transits to nascent clathrin-coated domains, where it diffuses at a slower rate while awaiting internalization., Competing Interests: Declaration of interests The authors declare no competing interests in this work., (Copyright © 2023 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Introduction Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Early detection and timely treatment have provided successful repair of the anomaly in the developed world. However, in the developing world, there is still a burden of uncorrected TOF patients reaching adulthood. The goal of this study is to determine whether there is any difference in postoperative complications between adult and pediatric populations following surgical correction for TOF. Methods This study involved all those patients who received primary or secondary surgical repair for TOF in our facility between January 2017 and December 2020. The patients were split according to their age into the pediatric group if they were under 18 years and the adult group if they were 18 years or older. Patients with absent pulmonary valve or pulmonary atresia were not included in this study. Patients with large major aortopulmonary collateral arteries (MAPCA) were also excluded from this study. All patients underwent total correction through a median sternotomy approach. The ventricular septal defect was closed with a Bard knitted fiber patch. The right ventricular outflow tract (RVOT) was augmented by excising muscle bands or fibrous bands in the RVOT. If the annulus was smaller than the 3.5 z score, then a transannular patch was done using an autologous pericardium. The main pulmonary artery was augmented in every surgery using an autologous pericardial patch. All patients were shifted to the ICU on the ventilator and were extubated after fulfillment of the extubation criteria. Postoperative complications measured included re-opening, re-intubation, prolonged ventilation (>24 hours), and mortality within the index hospital admission. The clinical data of all patients were prospectively collected and analyzed using the chi-square test and t-test. A p-value of less than or equal to 0.05 was considered significant. Results The total number of patients was 134. This included 83 males (60.1%). A total of 114 patients who were aged below 18 years were included in the pediatric group, and 20 patients aged equal to or more than 18 years were included in the adult group. The mean average perfusion time in minutes in the adult group was 125.8 and in the pediatric group, it was 98.79. Similarly, the mean average of the cross-clamp time was also longer in the adult group at 89.55 minutes versus 69.63 minutes in the pediatric group. Overall, in the adult group, three (15%) patients had postoperative complications, while in the pediatric group, a total of 14 (11.9%) patients had postoperative complications (p = 0.001). However, there was no significant difference in the number of re-openings (8.5% vs. 10%; p = 0.8). The total mortality observed was 16 (11.59%). This included 14 (11.9%) in the pediatric group and two (10%) in the adult group. There was no significant difference between the two groups (p = 0.8). Conclusions Surgical repair of TOF can be performed in both adult and pediatric populations with acceptable outcomes. The mortality rate was found to be slightly greater in the pediatric population compared to the adults. However, it can be seen that the number of postoperative complications is greater in adults. Further research is needed to optimize outcomes for both pediatric and adult patients with TOF., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Khan et al.)

A novel approach for the remediation of upland soils contaminated with pentachlorophenol (C 6 HCl 5 O; PCP) ( 1 ), a fungicide, wood perservative, and herbicide, through the exploitation of plant-endophytic bacteria may overcome the existing issues in bioaugmentaion and phytoremidiation. In this study, we isolated the endophytic Bacillus sp. strain PCP15 and determined its metabolite of PCP ( 1 ). This strain degraded 8.03 μmol L -1 PCP ( 1 ) within 24 h and generated the novel metabolite PCP phosphate ( 3 ). The PCP15 strain showed nearly complete growth inhibition of 20 μmol L -1 PCP ( 1 ). In contrast, PCP15 showed resistance to PCP phosphate ( 3 ), indicating that the phosphorylation of PCP, which has never previously been reported in organisms, contributed to the detoxification of PCP ( 1 ) in bacterial cells. Our results show the potential for practical application of this strain in hybrid remediation of PCP ( 1 )-contaminated soils and reveal a novel PCP ( 1 ) detoxification mechanism in organisms.

Biological hydrogels play important physiological roles in the body. These hydrogels often contain ordered subdomains that provide mechanical toughness and other tissue-specific functionality. Filamentous bacteriophages are nanofilaments with a high aspect ratio that can self-assemble into liquid crystalline domains that could be designed to mimic ordered biological hydrogels and can thus find applications in biomedical engineering. We have previously reported hydrogels of pure cross-linked liquid crystalline filamentous phage formed at very high concentrations exhibiting a tightly packed microstructure and high stiffness. In this work, we report a method for inducing self-assembly of filamentous phage into liquid crystalline hydrogels at concentrations that are several orders of magnitude below that of lyotropic liquid crystal formation, thus creating structural order but a less densely packed microstructure. Hybrid hydrogels of M13 phage and bovine serum albumin (0.25 w/v%) were formed and shown to adsorb up to 16× their weight in water. Neither component gelled on its own at the low concentrations used, suggesting synergistic action between the two components in the formation of the hydrogel. The hybrid hydrogels exhibited repetitive self-healing under physiological conditions and at room temperature, autofluorescence in three channels, and antibacterial activity toward Escherichia coli host cells. Furthermore, the hybrid hydrogels exhibited a more than 2× higher ability to pack water compared to BSA-only hydrogels and 2× lower compression modulus compared to tightly packed M13-only hydrogels, suggesting that our method could be used to create hydrogels with tunable mechanical properties and pore structure through the addition of globular proteins, while maintaining bioactivity and microscale structural order.

Pesticides to protect crops from pests are subject to rigorous risk assessment before registration in Japan. However, further information needs to be collected regarding the assessment of impacts on the natural environment. In particular, nitrifying bacteria play a role in converting ammonium salts to nitrates in soil. However, there is limited research covering the effects of insecticides on nitrification, despite several fungicides and herbicides have an inhibitory effect on nitrifying bacteria. Therefore, we investigated the effect of pesticides on the nitrification when applied to soil. The application of both pesticides promoted ammonia oxidation, and suppressed nitrite oxidation in a high-concentration treatment of dinotefuran. In addition, it was clarified that the diversity and species richness of soil bacteria was significantly reduced when the pesticides were applied to the soil, and that the specific soil bacteria (Metyhlotenera spp.) dominated the application of the pesticides.

Endophytic bacteria have been explored for their role in plant growth promotion, however, not much has been explored in cucumber. The metabolomic response of plants to application of such microbes also remains largely unknown. Thus, we investigated the application of endophytic bacteria to cucumber to infer their role in plant growth promotion and document metabolome response. The lowest healthy leaf-stalks were sampled from four differently sourced cucumber plants, and endophytic bacteria were isolated after surface disinfection. Initial plant growth-promoting (PGP) screening was performed to identify PGP strains out of numerous isolates, and five strains (Strains 4=Curtobacterium spp., 72=Brevibacillus spp., 167=Paenibacillus spp., 193=Bacillus spp., and 227=Microbacterium spp.) were selected based on their contribution to root growth compared with the control. The selected strains were further evaluated in pot experiments, axenic PGP trait assays, and metabolomic analysis. Results revealed that the selected isolates possessed different qualitative characteristics among indole acetic acid, siderophore production, phosphate solubilization, and 1-aminocyclopropane-1-carboxylate (ACC)-deaminase and nifH genes, and all isolates significantly enhanced plant growth in both pot experiments compared with the uninoculated control and fertilizer control. Metabolomic profiling revealed that both strains affected the plant metabolomes compared with the uninoculated control. Around 50 % of the metabolites explored had higher concentrations in either or both bacteria-applied plants compared with the uninoculated control. Differences were observed in both strains' regulation of metabolites, although both enhanced root growth near equally. Overall, endophytic bacteria significantly enhanced plant growth and tended to produce or induce release of certain metabolites within the plant endosphere., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Purpose: Interpreting a twelve‑lead electrocardiogram (ECG) is a basic, albeit essential skill for most healthcare professionals to attain. Despite its importance, evidence suggests that the competency of healthcare professionals to interpret ECGs can be improved. We evaluated the effectiveness of a national interactive workshop designed to improve ECG interpretation in the UK medical student cohort., Methods: UK medical students who attended a national workshop were asked to complete a pre- and post- workshop test which comprised of 20 ECGs which showed a variety of pathologies relating to conduction disturbances, tachycardia and acute coronary syndromes. The workshop was interactive and consisted of 6 h of ECG tutorials, divided into hourly sessions which covered all key topics such as 'basic electrophysiology' and 'electro-conduction problems'. Pre- and post-workshop test scores were compared by difference in means using the paired two-tailed t-test., Results: A total of 145 participants completed the pre-test and of those 44 completed both the pre and post-test. The mean pre-test and post-test scores were 9.7/20 questions (48.9%) and 11.2/20 questions (56.2%) respectively, with a mean improvement of 1.5/20 (7.3%) from pre- to post-test (+7.3%, 95% CI: +1.8 to +12.8%, p = 0.01)., Conclusion: A national ECG workshop which emphasizes activity-based learning may be effective in improving the competency of medical students to interpret ECGs. Further exploration with multi-center controlled studies involving a diverse cohort of students and analyses to determine their cost-effectiveness is warranted., Competing Interests: Declaration of competing interest None., (Copyright © 2019. Published by Elsevier Inc.)

Organic waste, including food leftovers and trade refuse, has been explored for its use as a nutrient source through a multitude of techniques. Composting; the dominant method, is criticized due to exhaustion of nutrients used for simultaneous microbial growth. Drying of food waste to low moisture levels, besides keeping the nutrition intact, offers the potential of growing desirable phyto-beneficial-cum-functional microbes, which can have additional benefits. Consequently, isolation of fungus from soil was carried out followed by characterization for confrontation against Fusarium, phosphate solubilization and utilization of food waste material. The food waste material was collected from University of Yamanashi Restaurant and dried up to approximately 3.8% moisture using Hitachi Household Garbage Dryer & Processor (ECO-B25). A pot experiment, growing Lactuca sativa (lettuce) and Brassica rapa, in selected fungal isolate-inoculated food waste material was conducted comparing with that of chemical, and organic fertilizer besides uninoculated food waste material. Results showed that one strain UY2015_11 (identified as Aspergillus niger) significantly inhibited the growth of Fusarium besides solubilizing hardly available iron, and calcium-type phosphates. Similarly, in a 13-week incubation experiment, mineralization of nitrate nitrogen from the food waste and fungal strain UY2015_11-inoculated food waste, was 23.9% and 17.0%, respectively. Later pot experiment indicated that the strain UY2015_11-inoculated dried food waste material showed same vegetable growth as chemical and organic fertilizer (rapeseed oil cake). Concluding, Aspergillus niger strain UY2015_11 isolated from soil inhibited the growth of Fusarium and solubilized hardly phosphate. Moreover, the strain UY2015_11 inoculated low moisture-food waste material showed the same vegetable growth as chemical and organic fertilizer (rapeseed oil cake)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Endophytic bacterial diversity in plants presents the level of interaction between culturable and non-culturable endophytic bacteria, thereby providing an appropriate insight into the endophytic environment. This study was conducted to determine the trend of culturable and non-culturable endophytic bacteria at two different sites encompassing four consecutive growth stages. For culturable endophytic bacteria, isolation was carried out using the dilution plate technique, and the obtained colonies were compared using PCR-restriction fragment length polymorphism (RFLP). Different RFLP-types were identified to their nearest neighbour using 16S rRNA sequencing. The non-culturable endophytic bacterial diversity was obtained by next generation sequencing. Results suggested a similar trend among the culturable and non-culturable bacteria for observed operational taxonomic units and diversity indices. It is noticeable that the endophytic bacteria inhabiting in stage 1 disappeared, and instead, different endophytic bacteria appeared. Moreover, the temporal persistence of certain culturable and non-culturable bacteria was also observed. In conclusion, the endophytic bacterial diversity in cucumber initially increased with the plant growth and then decreased at a later stage. Furthermore, it was suggested that plants regulate the number and diversity of endophytes throughout the lifecycle of plants.

Two enveloped viral vectors, vesicular stomatitis virus and influenza virus, and a non-enveloped viral vector, human adenovirus type 5, were encapsulated by spray drying to enhance thermal stability.Results with these candidates led to the hypothesis that stability performance of chosen excipients may be less virus-specific, as previously postulated in the literature, and more differentiated based on whether the virus has a lipid envelope. Spray dried samples were characterized for their thermal properties, RNA viability and in vitro viral activity after storage at 37 °C for up to 30 days or at 45 °C for up to 3 days. The enveloped viral vectors, as a group, were more thermally stable in trehalose while the non-enveloped viral vector showed higher activity with mannitol as the primary excipient in blends. Trehalose shows strong hydrogen bonds with the envelope's lipid membrane than the other carbohydrates, more effectively replacing water molecules while maintaining the fluidity of the membrane. Conversely, the small size of mannitol molecules was attributed to the more effective hydrogen bonding between water and the protein capsid of non-enveloped viral vectors. In all cases, a matrix with high glass transition temperature contributed to thermal stabilization through vitrification. This work suggests that carbohydrate stabilizer selection may be more dependent on the envelope rather than the specific viral vector, which, if universally true, will provide a guideline for future formulation development., (Copyright © 2019 Elsevier B.V. All rights reserved.)

With the advent of polymyxin B (PmB) resistance in bacteria, the mechanisms for mcr -1 resistance are of crucial importance in the design of novel therapeutics. The mcr -1 phenotype is known to decrease membrane charge and increase membrane packing by modification of the bacterial outer membrane. We used X-ray diffraction, Molecular Dynamics simulations, electrochemistry, and leakage assays to determine the location of PmB in different membranes and assess membrane damage. By varying membrane charge and lipid tail packing independently, we show that increasing membrane surface charge promotes penetration of PmB and membrane damage, whereas increasing lipid packing decreases penetration and damage. The penetration of the PmB molecules is well described by a phenomenological model that relates an attractive electrostatic and a repulsive force opposing insertion due to increased membrane packing. The model applies well to several gram-negative bacterial strains and may be used to predict resistance strength., Competing Interests: The authors declare no competing interests.

Beneficial microbes are applied to the soil and plant tissues directly or through seed inoculation, whereas soil application is preferred when there is risk of inhibitors or antagonistic microbes on the plant tissues. Insufficient survival of the microorganisms, hindrance in application of fungicides to the seeds and exposure to heat and sunlight in subsequent seed storage in conventional inoculation methods force to explore appropriate and efficient bacterial application method. Seed priming, where seeds are hydrated to activate metabolism without actual germination followed by drying, increases the germination, stand establishment and stress tolerance in different crops. Seed priming with living bacterial inoculum is termed as biopriming that involves the application of plant growth promoting rhizobacteria. It increases speed and uniformity of germination; also ensures rapid, uniform and high establishment of crops; and hence improves harvest quality and yield. Seed biopriming allows the bacteria to enter/adhere the seeds and also acclimatization of bacteria in the prevalent conditions. This review focuses on methods used for biopriming, and also the role in improving crop productivity and stress tolerance along with prospects of this technology. The comparison of methods being followed is also reviewed proposing biopriming as a promising technique for application of beneficial microbes to the seeds., (© FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

A super-absorbent hydrogel was developed by crosslinking of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and acrylic acid with hydroxypropyl methylcellulose (HPMC) for controlled release drug delivery of captopril, a well known antihypertensive drug. Acrylic acid and AMPS were polymerized and crosslinked with HPMC by free radical polymerization, a widely used chemical crosslinking method. N,N'-methylenebisacrylamide (MBA) and potassium persulfate (KPS) were added as cross-linker and initiator, respectively. The hydrogel formulation was loaded with captopril (as model drug). The concentration of captopril was monitored at 205 nm using UV spectrophotometer. Equilibrium swelling ratio was determined at pH 2, 4.5 and 7.4 to evaluate the pH responsiveness of the formed hydrogel. The super-absorbent hydrogels were evaluated by FTIR, SEM, XRD, and thermal analysis (DSC and TGA). The formation of new copolymeric network was determined by FTIR, XRD, TGA and DSC analysis. The hydrogel formulations with acrylic acid and AMPS ratio of 4: 1 and lower amounts of crosslinker had shown maximum swelling. Moreover, higher release rate of captopril was observed at pH 7.4 than at pH 2, because of more swelling capacity of copolymer with increasing pH of the aqueous medium. The present research work confirms the development of a stable hydrogel comprising of HPMC with acrylic acid and AMPS. The prepared hydrogels exhibited pH sensitive behav-ior. This superabsorbent composite prepared could be a successful drug carrier for treating hypertension.

Polyethylene oxide has been researched extensively as an alternative polymer to hydroxypropyl methylcellulose (HPMC) in controlled drug delivery due to its desirable swelling properties and its availability in a number of different viscosity grades. Previous studies on HPMC have pointed out the importance of particle size on drug release, but as of yet, no studies have investigated the effect of particle size of polyethylene oxide (polyox) on drug release. The present study explored the relationship between polymer level and particle size to sustain the drug release. Tablets produced contained theophylline as their active ingredient and consisted of different polyethylene oxide particle size fractions (20-45, 45-90, 90-180 and 180-425 μm). It was shown that matrices containing smaller particle sizes of polyox produced harder tablets than when larger polyox particles were used. The release studies showed that matrices consisting of large polyox particles showed a faster release rate than matrices made from smaller particles. Molecular weight (MW) of the polymer was a key determining step in attaining sustained release, with the high MW of polyox resulting in a delayed release profile. The results showed that the effect of particle size on drug release was more detrimental when a low concentration of polyox was used. This indicates that care must be taken when low levels of polyox with different particle size fractions are used. More robust formulations could be obtained when the concentration of polyox is high. Differential scanning calorimetry (DSC) traces showed that particle size had no major effect on the thermal behaviour of polyox particles.