Extraction, Modification and Biomedical Application of Agarose Hydrogels: A Review.

Numerous compounds present in the ocean are contributing to the development of the biomedical field. Agarose, a polysaccharide derived from marine red algae, plays a vital role in biomedical applications because of its reversible temperature-sensitive gelling behavior, excellent mechanical properties, and high biological activity. Natural agarose hydrogel has a single structural composition that prevents it from adapting to complex biological environments. Therefore, agarose can be developed into different forms through physical, biological, and chemical modifications, enabling it to perform optimally in different environments. Agarose biomaterials are being increasingly used for isolation, purification, drug delivery, and tissue engineering, but most are still far from clinical approval. This review classifies and discusses the preparation, modification, and biomedical applications of agarose, focusing on its applications in isolation and purification, wound dressings, drug delivery, tissue engineering, and 3D printing. In addition, it attempts to address the opportunities and challenges associated with the future development of agarose-based biomaterials in the biomedical field. It should help to rationalize the selection of the most suitable functionalized agarose hydrogels for specific applications in the biomedical industry.

Oral health in patients with dementia: A meta-analysis of comparative and observational studies.

OBJECTIVE: Poor oral health is common in dementia, but findings of epidemiological studies have been inconsistent. This meta-analysis examined oral health in patients with dementia diagnosed according to standardized diagnostic criteria. METHODS: Six international databases (PubMed, EMBASE, PsycINFO, Medline, Cochrane Library, and Web of Science) were searched from their commencement date until 8 November 2018. Oral health was measured by the Remaining Teeth (RT) and Decayed, Missing, and Filled Teeth (DMFT) Index. The mean differences (MD) and 95% confidence intervals (CI) of DMFT Index total and component scores were calculated using a random-effect model. RESULTS: Twenty-four studies were included for analyses. The pooled DMFT Index was 23.48 (95% CI: 22.34, 24.62), while the pooled score for each component was 2.38 (95% CI: 1.56, 3.20) in decayed teeth (DT), 18.39 (95% CI: 15.92, 20.87) in missing teeth (MT), 2.29 (95% CI: 0.62, 3.95) in filled teeth (FT), and 11.59 (95% CI: 9.14, 14.05) in RT. Compared to controls, people with dementia had significantly a higher DMFT Index total score (MD = 3.80, 95% CI: 2.21, 5.39, p < 0.00,001), and significantly lower number of RT (MD = -3.15, 95% CI: -4.23, -2.06, p < 0.00,001). Subgroup analyses revealed that higher DMFT Index score was significantly associated with year of survey (>2010), study design (case-control study), percentage of females (≤54.3), and the Mini Mental State Examination score (≤18.2). Higher MT score was significantly associated with study design (cross-sectional study), and lower FT score was significantly associated with year of survey (>2010). CONCLUSIONS: Oral health was significantly poorer in people with dementia compared with controls. Regular screening and effective treatment should be implemented for this population.

Agarose Stearate-Carbomer940 as Stabilizer and Rheology Modifier for Surfactant-Free Cosmetic Formulations.

Some commonly used surfactants in cosmetic products raise concerns due to their skin-irritating effects and environmental contamination. Multifunctional, high-performance polymers are good alternatives to overcome these problems. In this study, agarose stearate (AS) with emulsifying, thickening, and gel properties was synthesized. Surfactant-free cosmetic formulations were successfully prepared from AS and carbomer940 (CBM940) mixed systems. The correlation of rheological parameter with skin feeling was determined to study the usability of the mixed systems in cosmetics. Based on rheological analysis, the surfactant-free cosmetic cream (SFC) stabilized by AS-carbomer940 showed shear-thinning behavior and strongly synergistic action. The SFC exhibited a gel-like behavior and had rheological properties similar to commercial cosmetic creams. Scanning electron microscope images proved that the AS-CBM940 network played an important role in SFC's stability. Oil content could reinforce the elastic characteristics of the AS-CBM940 matrix. The SFCs showed a good appearance and sensation during and after rubbing into skin. The knowledge gained from this study may be useful for designing surfactant-free cosmetic cream with rheological properties that can be tailored for particular commercial cosmetic applications. They may also be useful for producing medicine products with highly viscous or gel-like textures, such as some ointments and wound dressings.

Genome-wide identification of rubber tree (Hevea brasiliensis Muell. Arg.) aquaporin genes and their response to ethephon stimulation in the laticifer, a rubber-producing tissue.

BACKGROUND: Natural rubber, an important industrial raw material, is specifically synthesized in laticifers located inside the rubber tree (Hevea brasiliensis Muell. Arg.) trunk. Due to the absence of plasmodesmata, the laticifer water balance is mediated by aquaporins (AQPs). However, to date, the characterization of H. brasiliensis AQPs (HbAQPs) is still in its infancy. RESULTS: In this study, 51 full-length AQP genes were identified from the rubber tree genome. The phylogenetic analysis assigned these AQPs to five subfamilies, including 15 plasma membrane intrinsic proteins (PIPs), 17 tonoplast intrinsic proteins (TIPs), 9 NOD26-like intrinsic proteins (NIPs), 4 small basic intrinsic proteins (SIPs) and 6 X intrinsic proteins (XIPs). Functional prediction based on the analysis of the aromatic/arginine (ar/R) selectivity filter, Froger's positions and specificity-determining positions (SDPs) showed a remarkable difference in substrate specificity among subfamilies. Homology analysis supported the expression of 44 HbAQP genes in at least one of the examined tissues. Furthermore, deep sequencing of the laticifer transcriptome in the form of latex revealed a key role of several PIP subfamily members in the laticifer water balance, and qRT-PCR analysis showed diverse expression patterns of laticifer-expressed HbAQP genes upon ethephon treatment, a widely-used practice for the stimulation of latex yield. CONCLUSIONS: This study provides an important genetic resource of HbAQP genes, which will be useful to improve the water use efficiency and latex yield of Hevea.

Odontogenic Keratocyst in Maxillary Sinus with Ectopic Third Molar: A Case Report.

BACKGROUND Odontogenic keratocyst (OKC) is a common odontogenic cyst, and it occurs more frequently in the mandible, with the posterior region of the dental arch, the angle, or the ramus being the most commonly affected sites. Odontogenic keratocyst occurring within the maxillary sinus is extremely rare, accounting for only about 1% of cases. CASE REPORT A 20-year-old female patient without any clinical symptoms underwent an oral examination, during which a dense dental shadow was identified within the maxillary sinus, surrounded by a low-density shadow. Physical examination revealed absence of the left maxillary third molar, with intact mucosa. The patient reported no history of tooth extraction. X-ray and cone-beam computed tomography revealed a high-density image within the left maxillary sinus, resembling a tooth and surrounded by a soft-tissue shadow, which exhibited a greater density in comparison to conventional odontogenic cysts. The initial diagnosis was odontogenic keratocyst in the maxillary sinus with an ectopic maxillary third molar. Surgical enucleation of the cyst and extraction of the impacted tooth were carried out utilizing the Caldwell-Luc approach. Histopathological analysis confirmed the presence of OKC. No significant recurrence was noted during the 6 months of follow-up. CONCLUSIONS Odontogenic keratocysts in the maxillary sinus with ectopic third molar are rare and may not have any symptoms in the early stage. Surgery can be performed using the Caroler-Luke approach to achieve ideal treatment results. In view of the high recurrence rate of OKC, close follow-up should be conducted after surgery.

Regenerated cellulose I from LiCl·DMAc solution.

The regeneration of cellulose from microcrystalline cellulose/DMAc·LiCl solutions through thermal induced sol-gel transition and longtime gelation resulted in the formation of wholly cellulose I with a crystallinity as high as 84.7%.

Regulation of HbPIP2;3, a Latex-Abundant Water Transporter, Is Associated with Latex Dilution and Yield in the Rubber Tree (Hevea brasiliensis Muell. Arg.).

Rubber tree (Hevea brasiliensis) latex, the source of natural rubber, is synthesised in the cytoplasm of laticifers. Efficient water inflow into laticifers is crucial for latex flow and production since it is the determinant of the total solid content of latex and its fluidity after tapping. As the mature laticifer vessel rings are devoid of plasmodesmata, water exchange between laticifers and surrounding cells is believed to be governed by plasma membrane intrinsic proteins (PIPs). To identify the most important PIP aquaporin in the water balance of laticifers, the transcriptional profiles of ten-latex-expressed PIPs were analysed. One of the most abundant transcripts, designated HbPIP2;3, was characterised in this study. When tested in Xenopus laevis oocytes HbPIP2;3 showed a high efficiency in increasing plasmalemma water conductance. Expression analysis indicated that the HbPIP2;3 gene was preferentially expressed in latex, and the transcripts were up-regulated by both wounding and exogenously applied Ethrel (a commonly-used ethylene releaser). Although regular tapping up-regulated the expression of HbPIP2;3 during the first few tappings of the virginal rubber trees, the transcriptional kinetics of HbPIP2;3 to Ethrel stimulation in the regularly tapped tree exhibited a similar pattern to that of the previously reported HbPIP2;1 in the virginal rubber trees. Furthermore, the mRNA level of HbPIP2;3 was associated with clonal yield potential and the Ethrel stimulation response. Together, these results have revealed the central regulatory role of HbPIP2;3 in laticifer water balance and ethylene stimulation of latex production in Hevea.

Time- and pH-dependent colon-specific drug delivery for orally administered diclofenac sodium and 5-aminosalicylic acid.

AIM: To investigate Time- and pH-dependent colon-specific drug delivery systems (CDDS) for orally administered diclofenac sodium (DS) and 5-aminosalicylic acid (5-ASA), respectively. METHODS: DS tablets and 5-ASA pellets were coated by ethylcellulose (EC) and methacrylic acid copolymers (Eudragit L100 and S100), respectively. The in vitro release behavior of the DS coated tablets and 5-ASA coated pellets were examined, and then in vivo absorption kinetics of DS coated tablets in dogs were further studied. RESULTS: Release profile of time-dependent DS coated tablets was not influenced by pH of the dissolution medium, but the lag time of DS release was primarily controlled by the thickness of the coating layer. The thicker the coating layer, the longer the lag time of DS release is. On the contrary, in view of the pH-dependent 5-ASA coated pellets, 5-ASA release was significantly governed by pH. Moreover, the 5-ASA release features from the coated pellets depended upon both the combination ratio of the Eudragit L100 and S100 pH-sensitive copolymers in the coating formulation and the thickness of the coating layer. The absorption kinetic studies of the DS coated tablets in dogs demonstrated that in vivo lag time of absorption was in a good agreement with in vitro lag time of release. CONCLUSION: Two types of CDDS, prepared herein by means of the regular coating technique, are able to achieve site-specific drug delivery targeting at colon following oral administration, and provide a promising strategy to control drug release targeting the desired lower gastrointestinal region.