Reactivity ratio estimation in copolymerization: a new analysis of unresolved conflicts

Using a stochastic approach, a fresh analysis has been provided to resolve the possible causes of the existing conflicts in the reactivity ratio estimation in copolymerization systems. The analysis provides some new clues regarding the inadequacy of a transient system (batch reactor) and suggests the use of a steady state operation (CSTR) as a more reliable method

DETERMINATION OF ALOGLIPTIN BENZOATE AND METFORMIN HYDROCHLORIDE IN TABLET DOSAGE FORM BY SIMULTANEOUS EQUATION AND ABSORPTION RATIO METHOD

Objective: Development and validation of two simple, rapid, accurate and sensitive UV-spectrophotometric methods for simultaneous estimation of alogliptin benzoate (ALO) and metformin hydrochloride (MET) in bulk and tablet dosage form.Methods: First method (Method A) is simultaneous equation method, which is based on the measurement of absorption at 224 nm and 237 nm for both ALO and MET, respectively. Second method (Method B) is an absorption ratio method, which is based on the measurement of absorption at 251 nm i.e. Iso-absorptive point of ALO and MET and 224 nm which is λmax of ALO.Results: Both the drugs were found to be linear in the concentration range of 0.5-18 µg/ml and correlation co-efficient was found to be 0.9998 and 0.9992 for ALO and 0.9998 and 1 for MET at 224 nm and 237 nm, respectively for simultaneous equation method. For absorption ratio method, both the drugs were found to be linear in the concentration range of 0.5-18 µg/ml and correlation co-efficient was found to be 0.9998 and 0.9997 for ALO and 0.9998 and 0.9997 for MET at 224 nm and 251 nm, respectively. Recovery studies at 50, 100 and 150% levels were carried out to assess accuracy of the methods. Precision studies were also carried out and %RSD was found to be within the limit (% RSD<2). The percentage assay (Method A) was found to be 100.57±1.1367 and 101.24±1.0936 for ALO and MET, respectively. For Method B, percentage assay was found to be 101.46±0.7160 for ALO and 100.15±0.6953 for MET.Conclusion: The developed methods were found to be simple, rapid, accurate and sensitive. Therefore, both the methods can be successfully applied for simultaneous determination of ALO and MET in tablet formulation.Â

QUANTITATIVE SIMULTANEOUS DETERMINATION OF ALISKIREN HEMIFUMARATE AND HYDROCHLOROTHIAZIDE IN COMBINED TABLET FORMULATION BY RP-HPLC

Objective: Development and validation of quantitative simultaneous determination of aliskiren hemifumarate (ALI) and hydrochlorothiazide (HCT) in combined tablet formulation by RP-HPLC.Methods: The separation of components were achieved on Enable C18 column (250×4.6 mm, 5 µm) with a mobile phase consisting of 0.2 %v/v triethylamine in water (pH 6 was adjusted with orthophosphoric acid): methanol (10:90 %v/v) at a flow rate of 1 ml/min was employed. Quantification was achieved with PDA detection at 280 nm. Validation parameters of the proposed method such as specificity, linearity, accuracy, precision and robustness were evaluated according to ICH guidelines.Results: Linear concentration range was between 1.2-240 µg/ml for ALI and 0.1-20 µg/ml for HCT and correlation coefficient was found to be 0.9995 and 0.9998, respectively. The limit of detection and limit of quantification for ALI was found to be 0.3376 and 1.0230 µg/ml and for HCT 0.0288 and 0.0873 µg/ml, respectively. The results of precision (% RSD<2) studies showed good reproducibility. Recovery study was performed at 50, 100 and 150 % level to check the interferences between analytes and formulation excipients and % recovery was found to be 99.49±0.9868 for ALI and 99.87±0.8556 for HCT. The percentage assay was found to be 100.36±0.9201 and 99.40±0.7624 for ALI and HCT, respectively.Conclusion: A simple, rapid, cost effective and highly sensitive RP-HPLC method as compared to existing methods for the determination of ALI and HCT in tablet formulation was developed and validated as per ICH guidelines. The method uses simple reagents and sample preparation procedures were minimal. Thus, the proposed method can be applied for routine quality control determination of ALI and HCT in tablet formulation.Â

Malaria in Sri Lanka: one year post-tsunami

One year ago, the authors of this article reported in this journal on the malaria situation in Sri Lanka prior to the tsunami that hit on 26 December 2004, and estimated the likelihood of a post-tsunami malaria outbreak to be low. Malaria incidence has decreased in 2005 as compared to 2004 in most districts, including the ones that were hit hardest by the tsunami. The malaria incidence (aggregated for the whole country) in 2005 followed the downward trend that started in 2000. However, surveillance was somewhat affected by the tsunami in some coastal areas and the actual incidence in these areas may have been higher than recorded, although there were no indications of this and it is unlikely to have affected the overall trend significantly. The focus of national and international post tsunami malaria control efforts was supply of antimalarials, distribution of impregnated mosquito nets and increased monitoring in the affected area. Internationally donated antimalarials were either redundant or did not comply with national drug policy, however, few seem to have entered circulation outside government control. Despite distribution of mosquito nets, still a large population is relatively exposed to mosquito bites due to inadequate housing. There were no indications of increased malaria vector abundance. Overall it is concluded that the tsunami has not negatively influenced the malaria situation in Sri Lanka

Dysregulation of the mTOR Pathway Mediates Impairment of Synaptic Plasticity in a Mouse Model of Alzheimer's Disease

Background: The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr protein kinase that plays a pivotal role in multiple fundamental biological processes, including synaptic plasticity. We explored the relationship between the mTOR pathway and b-amyloid (Ab)-induced synaptic dysfunction, which is considered to be critical in the pathogenesis of Alzheimer’s disease (AD). Methodology/Principal Findings: We provide evidence that inhibition of mTOR signaling correlates with impairment in synaptic plasticity in hippocampal slices from an AD mouse model and in wild-type slices exposed to exogenous Ab1-42. Importantly, by up-regulating mTOR signaling, glycogen synthase kinase 3 (GSK3) inhibitors rescued LTP in the AD mouse model, and genetic deletion of FK506-binding protein 12 (FKBP12) prevented Ab-induced impairment in long-term potentiation (LTP). In addition, confocal microscopy demonstrated co-localization of intraneuronal Ab42 with mTOR. Conclusions/Significance: These data support the notion that the mTOR pathway modulates Ab-related synaptic dysfunctio

Nicotine exposure and transgenerational impact: a prospective study on small regulatory microRNAs

Early developmental stages are highly sensitive to stress and it has been reported that pre-conditioning with tobacco smoking during adolescence predisposes those youngsters to become smokers as adults. However, the molecular mechanisms of nicotine-induced transgenerational consequences are unknown. In this study, we genome-widely investigated the impact of nicotine exposure on small regulatory microRNAs (miRNAs) and its implication on health disorders at a transgenerational aspect. Our results demonstrate that nicotine exposure, even at the low dose, affected the global expression profiles of miRNAs not only in the treated worms (F0 parent generation) but also in two subsequent generations (F1 and F2, children and grandchildren). Some miRNAs were commonly affected by nicotine across two or more generations while others were specific to one. The general miRNA patterns followed a “two-hit� model as a function of nicotine exposure and abstinence. Target prediction and pathway enrichment analyses showed daf-4, daf-1, fos-1, cmk-1, and unc-30 to be potential effectors of nicotine addiction. These genes are involved in physiological states and phenotypes that paralleled previously published nicotine induced behavior. Our study offered new insights and further awareness on the transgenerational effects of nicotine exposed during the vulnerable post-embryonic stages, and identified new biomarkers for nicotine addiction.ECU Open Access Publishing Support Fun

Pseudohyperphosphorylation has differential effects on polymerization and function of tau isoforms

The microtubule-associated protein tau exists as six isoforms created through the splicing of the second, third, and tenth exons. The isoforms are classified by their number of N-terminal exons (0N, 1N or 2N) and by their number of microtubule-binding repeat regions (3R or 4R). Hyperphosphorylated isoforms accumulate in insoluble aggregates in Alzheimer’s disease and other tauopathies. These neurodegenerative diseases can be categorized based on the isoform content of the aggregates they contain. Hyperphosphorylated tau has the general characteristics of an upward electrophoretic shift, decreased microtubule binding, and an association with aggregation. Previously we have shown that a combination of seven pseudophosphorylation mutations at sites phosphorylated by GSK-3β, referred to as 7-Phos, induced several of these characteristics in full-length 2N4R tau and led to the formation of fewer but longer filaments. We sought to determine whether the same phosphorylation pattern could cause differential effects in the other tau isoforms, possibly through varied conformational effects. Using in vitro techniques, we examined the electrophoretic mobility, aggregation properties and microtubule stabilization of all isoforms and their pseudophosphorylated counterparts. We found that pseudophosphorylation affected each isoform, but in several cases certain isoforms were affected more than others. These results suggest that hyperphosphorylation of tau isoforms could play a major role in determining the isoform composition of tau aggregates in disease

Razvoj i karakterizacija mukoadhezivnih flastera salbutamol sulfata za jednosmjernu bukalnu isporuku

Buccal patches of salbutamol sulfate were prepared using five different water soluble polymers in various proportions and combinations using PEG-400/PG as plasticizers. A 32 full factorial design was used to design the experiments for each polymer combination. Patches were laminated on one side with a water impermeable backing layer for unidirectional drug release. The thickness of medicated patches ranged between 0.2 and 0.4 mm and showed an increase in mass whenever PEG-400 was used as plasticizer. The surface pH of all patches approached neutral. Eight formulations which had shown high folding endurance (> 300) were selected for evaluation. Patches prepared with PEG-400 showed a high swelling index. The residence time of the tested patches ranged between 105 and 130 min. Formulations A10, A32, B10 and B32 fitted the Higuchi model best, whereas formulations A19 and B19 showed super case II transport drug release. Stability studies indicated that there was no change in the chemical and physical characteristics during the test period of 6 months.U radu je opisana priprava flastera za bukalnu primjenu upotrebom različitih omjera pet vodotopljivih polimera i PEG-400/PG kao plastifikatora. Potpuni 32 faktorijalni dizajn upotrebljen je za dizajniranje eksperimenata za svaku kombinaciju polimera. Flasteri su postavljeni na jednu stranu usta s vodonepropusnom podlogom, koja omogućava jednosmjerno oslobađanje lijeka. Debljina flastera varirala je između 0,2 i 0,4 nm. Flasteri s PEG-400 bili su malo veće mase. pH na površini svih flastera bio je blizu neutralnog. Osam pripravaka vrlo otpornih na presavijanje (300) izabrano je za daljnju evaluaciju. Flasteri pripravljeni s PEG 400 imali su veliku sposobnost bubrenja. Flasteri su se zadržali na mjestu primjene između 105 i 130 min. Pripravci A10, A32, B10 i B32 najbolje su slijedili Higuchijev model, dok su pripravci A19 i B19 pokazivali anomalno oslobađanje koje ne slijedi Fickov zakon. Ispitivanje stabilnosti pokazalo je da ne postoje promjene u kemijskim i fizikalnim svojstvima pripravaka tijekom 6 mjeseci

Characterizing Long COVID in Children and Adolescents

ImportanceMost research to understand postacute sequelae of SARS-CoV-2 infection (PASC), or long COVID, has focused on adults, with less known about this complex condition in children. Research is needed to characterize pediatric PASC to enable studies of underlying mechanisms that will guide future treatment.ObjectiveTo identify the most common prolonged symptoms experienced by children (aged 6 to 17 years) after SARS-CoV-2 infection, how these symptoms differ by age (school-age [6-11 years] vs adolescents [12-17 years]), how they cluster into distinct phenotypes, and what symptoms in combination could be used as an empirically derived index to assist researchers to study the likely presence of PASC.Design, setting, and participantsMulticenter longitudinal observational cohort study with participants recruited from more than 60 US health care and community settings between March 2022 and December 2023, including school-age children and adolescents with and without SARS-CoV-2 infection history.ExposureSARS-CoV-2 infection.Main outcomes and measuresPASC and 89 prolonged symptoms across 9 symptom domains.ResultsA total of 898 school-age children (751 with previous SARS-CoV-2 infection [referred to as infected] and 147 without [referred to as uninfected]; mean age, 8.6 years; 49% female; 11% were Black or African American, 34% were Hispanic, Latino, or Spanish, and 60% were White) and 4469 adolescents (3109 infected and 1360 uninfected; mean age, 14.8 years; 48% female; 13% were Black or African American, 21% were Hispanic, Latino, or Spanish, and 73% were White) were included. Median time between first infection and symptom survey was 506 days for school-age children and 556 days for adolescents. In models adjusted for sex and race and ethnicity, 14 symptoms in both school-age children and adolescents were more common in those with SARS-CoV-2 infection history compared with those without infection history, with 4 additional symptoms in school-age children only and 3 in adolescents only. These symptoms affected almost every organ system. Combinations of symptoms most associated with infection history were identified to form a PASC research index for each age group; these indices correlated with poorer overall health and quality of life. The index emphasizes neurocognitive, pain, and gastrointestinal symptoms in school-age children but change or loss in smell or taste, pain, and fatigue/malaise-related symptoms in adolescents. Clustering analyses identified 4 PASC symptom phenotypes in school-age children and 3 in adolescents.Conclusions and relevanceThis study developed research indices for characterizing PASC in children and adolescents. Symptom patterns were similar but distinguishable between the 2 groups, highlighting the importance of characterizing PASC separately for these age ranges