Preparation and Evaluation of Differently Sulfonated Styrene–Divinylbenzene Cross-linked Copolymer Cationic Exchange Resins as Novel Carriers for Drug Delivery

The differently sulfonated styrene–divinylbenzene cross-linked copolymer cationic exchange resins were prepared by oil-in-water polymerization and varied degrees of sulfonation. Several characteristics of the obtained resins were evaluated, i.e., Fourier transform infrared spectra, the ion-exchange capacity, microscopic morphology, size, and swelling. The resin characteristics were altered in relation to the degree of sulfonation, proving that differently sulfonated resins could be prepared. The behavior of chlorpheniramine (CPM) loading and in vitro release in the USP simulated gastric (SGF) and intestinal fluids (SIF) of the obtained resins were also evaluated. The CPM loaded in the resinates (drug-loaded resins) increased with the increasing degree of sulfonic group and hence the drug binding site in the employed resins. The CPM release was lower from the resins with the higher degree of sulfonic group due to the increase in the diffusive path depth. The CPM release was obviously lower in SGF than SIF because CPM, a weak base drug, ionized to a greater extent in SGF and then preferred binding with rather than releasing from the resins. In conclusion, the differently sulfonated resins could be utilized as novel carriers for drug delivery.     

Pneumococcal Bacteremia Requiring Hospitalization in Rural Thailand: An Update on Incidence,Clinical Characteristics,Serotype Distribution,and Antimicrobial Susceptibility, 2005–2010

Background

Streptococcus pneumoniae is an important cause of morbidity and mortality in Southeast Asia, but regional data is limited. Updated burden estimates are critical as pneumococcal conjugate vaccine (PCV) is highly effective, but not yet included in the Expanded Program on Immunization of Thailand or neighboring countries.

Methods

We implemented automated blood culture systems in two rural Thailand provinces as part of population-based surveillance for bacteremia. Blood cultures were collected from hospitalized patients as clinically indicated.

Results

From May 2005– March 2010, 196 cases of pneumococcal bacteremia were confirmed in hospitalized patients. Of these, 57% had clinical pneumonia, 20% required mechanical ventilation, and 23% (n = 46) died. Antibiotic use before blood culture was confirmed in 25% of those with blood culture. Annual incidence of hospitalized pneumococcal bacteremia was 3.6 per 100,000 person-years; rates were higher among children aged <5 years at 11.7 and adults ≥65 years at 14.2, and highest among infants <1 year at 33.8. The median monthly case count was higher during December–March compared to the rest of the year 6.0 vs. 1.0 (p<0.001). The most common serotypes were 23F (16%) and 14 (14%); 61% (74% in patients <5 years) were serotypes in the 10-valent PCV (PCV 10) and 82% (92% in <5 years) in PCV 13. All isolates were sensitive to penicillin, but non-susceptibility was high for co-trimoxazole (57%), erythromycin (30%), and clindamycin (20%).

Conclusions

We demonstrated a high pneumococcal bacteremia burden, yet underestimated incidence because we captured only hospitalized cases, and because pre-culture antibiotics were frequently used. Our findings together with prior research indicate that PCV would likely have high serotype coverage in Thailand. These findings will complement ongoing cost effectiveness analyses and support vaccine policy evaluation in Thailand and the region.     

Cloning of the crustacean hyperglycemic hormone and evidence for molt-inhibiting hormone within the central nervous system of the blue crab Portunus pelagicus

The crustacean X-organ–sinus gland (XO–SG) complex controls molt-inhibiting hormone (MIH) production, although extra expression sites for MIH have been postulated. Therefore, to explore the expression of MIH and distinguish between the crustacean hyperglycemic hormone (CHH) superfamily, and MIH immunoreactive sites (ir) in the central nervous system (CNS), we cloned a CHH gene sequence for the crab Portunus pelagicus (Ppel-CHH), and compared it with crab CHH-type I and II peptides. Employing multiple sequence alignments and phylogenic analysis, the mature Ppel-CHH peptide exhibited residues common to both CHH-type I and II peptides, and a high degree of identity to the type-I group, but little homology between Ppel-CHH and Ppel-MIH (a type II peptide). This sequence identification then allowed for the use of MIH antisera to further confirm the identity and existence of a MIH-ir 9 kDa protein in all neural organs tested by Western blotting, and through immunohistochemistry, MIH-ir in the XO, optic nerve, neuronal cluster 17 of the supraesophageal ganglion, the ventral nerve cord, and cell cluster 22 of the thoracic ganglion. The presence of MIH protein within such a diversity of sites in the CNS, and external to the XO–SG, raises new questions concerning the established mode of MIH action.     

Meloxicam Taste-Masked Oral Disintegrating Tablet with Dissolution Enhanced by Ion Exchange Resins and Cyclodextrin

The purpose of this study was to develop taste-masked oral disintegrating tablets (ODTs) using the combination of ion exchange resin and cyclodextrin, to mask the bitter taste and enhance drug dissolution. Meloxicam (MX) was selected as a model drug with poor water solubility and a bitter taste. Formulations containing various forms of MX (free drug, MX-loaded resin or resinate, complexes of MX and 2-hydroxypropyl-β-cyclodextrin (HPβCD) or MX/HPβCD complexes, and a mixture of resinate and MX/HPβCD complexes) were made and tablets were prepared by direct compression. The ODTs were evaluated for weight variation, thickness, diameter, hardness, friability, disintegration time, wetting time, MX content, MX release, degree of bitter taste, and stability. The results showed that thickness, diameter, weight, and friability did not differ significantly for all of these formulations. The tablet hardness was approximately 3 kg/in.², and the friability was less than 1%. Tablets formulated with resinate and the mixture of resinate and MX/HPβCD complexes disintegrated rapidly within 60 s, which is the acceptable limit for ODTs. These results corresponded to the in vivo disintegration and wetting times. However, only tablets containing the mixture of resinate and MX/HPβCD complexes provided complete MX dissolution and successfully masked the bitter taste of MX. In addition, this tablet was stable at least 6 months. The results from this study suggest that the appropriate combination of ion exchange resin and cyclodextrin could be used in ODTs to mask the bitter taste of drug and enhance the dissolution of drugs that are weakly soluble in water.     

Changes of Phosphatidylcholine and Fatty Acids in Germ Cells during Testicular Maturation in Three Developmental Male Morphotypes of Macrobrachium rosenbergii Revealed by Imaging Mass Spectrometry

Testis maturation, germ cell development and function of sperm, are related to lipid composition. Phosphatidylcholines (PCs) play a key role in the structure and function of testes. As well, increases of polyunsaturated fatty acids (PUFA) and highly unsaturated fatty acids (HUFA), especially arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are essential for male fertility. This study is the first report to show the composition and distribution of PCs and total fatty acids (FAs) in three groups of seminiferous tubules (STs) classified by cellular associations [i.e., A (STs with mostly early germ cells), B (STs with mostly spermatids), and C (STs with spermatozoa)], in three morphotypes of Macrobrachium rosenbergii, [i.e., small male (SM), orange claw male (OC), and blue claw male (BC)]. Thin layer chromatography exhibited levels of PCs reaching maxima in STs of group B. Imaging mass spectrometry showed remarkably high signals corresponding to PC (16:0/18:1), PC (18:0/18:2), PC (18:2/20:5), and PC (16:0/22:6) in STs of groups A and B. Moreover, most signals were detected in the early developing cells and the intertubular area, but not at the area containing spermatozoa. Finally, gas chromatography-mass spectrometry indicated that the major FAs present in the testes were composed of 14:0, 16:0, 17:0, 18:0, 16:1, 18:1, 18:2, 20:1, 20:2, 20:4, 20:5, and 22:6. The testes of OC contained the greatest amounts of these FAs while the testes of BC contained the least amounts of these FAs, and there was more EPA (20:5) in the testes of SM and OC than those in the BC. The increasing amounts of FAs in the SM and OC indicate that they are important for spermatogenesis and spermiogenesis. This knowledge will be useful in formulating diets containing PUFA and HUFA for prawn broodstocks in order to improve testis development, and lead to increased male fecundity.     

Effect of molecular weight of chitosan on antimicrobial properties and tissue compatibility of chitosan-impregnated bacterial cellulose films

Bacterial cellulose-chitosan (BC-C) films were developed by immersing purified BC pellicles in 1.5 ~ 2.0% (w/v) acetic acid solutions containing chitosan of varying molecular weights. Effects of different molecular weight of chitosan on physical, biological and antimicrobial properties of the composite films were investigated. The cumulative chitosan absorption capacities with M_w of 141,000, 199,000, and 263,000 were 38.43, 24.65, and 23.89 mg/cm³ of dry BC film, respectively. The cumulative release profiles of chitosan from the films strongly depended on molecular weight of chitosan and pH of solution. The order of release of chitosan from the BC-C films was dependent on molecular weight as follows: M_w 141,000 > M_w 199,000 > M_w 263,000. All BC-C films showed the antimicrobial abilities against Staphylococcus aureus and Aspergillus niger but had no inhibitory effect on the growth of Escherichia coli. The BC-C films supported for adhesion, spreading and proliferation of both human skin keratinocytes and fibroblasts. The antibacterial activity against S. aureus of the BC-C with the highest Mw chitosan (263,000) was higher than those of the others. On the other hand, the BC-C films with the lowest M_w chitosan (141,000) promoted the growth of human skin cells more than those of the others.     

Overcoming Efficiency Limitations of SnS‐Based Solar Cells

Thin‐film solar cells are made by vapor deposition of Earth‐abundant materials: tin, zinc, oxygen and sulfur. These solar cells had previously achieved an efficiency of about 2%, less than 1/10 of their theoretical potential. Loss mechanisms are systematically investigated and mitigated in solar cells based on p‐type tin monosulfide, SnS, absorber layers combined with n‐type zinc oxysulfide, Zn(O,S) layers that selectively transmit electrons, but block holes. Recombination at grain boundaries is reduced by annealing the SnS films in H₂S to form larger grains with fewer grain boundaries. Recombination near the p‐SnS/n‐Zn(O,S) junction is reduced by inserting a few monolayers of SnO₂ between these layers. Recombination at the junction is also reduced by adjusting the conduction band offset by tuning the composition of the Zn(O,S), and by reducing its free electron concentration with nitrogen doping. The resulting cells have an efficiency over 4.4%, which is more than twice as large as the highest efficiency obtained previously by solar cells using SnS absorber layers.