Polydopamine-Coated Silk Fiber with Controllable Length for Enhanced Hemostatic Application

The development of highly effective hemostatic materials with high biocompatibility and outstanding performance is vital to the field of biomaterials. In this study, we develop a hemostatic fiber material that exhibits high biocompatibility and excellent performance. By incorporating polydopamine (PDA) into the alkaline treatment of silk fibroin (SF), we achieve PDA-coated SF fibers with lengths that can be controlled by the alkaline concentration. The PDA coating significantly enhances the hemostatic ability of the silk fibers and exhibits superior performance in both in vitro and ex vivo experiments. By performing animal studies involving a mouse liver puncture model and a femoral vein incision model, we demonstrate the remarkable hemostatic capability of the PDA-coated SF fibers, as evidenced by the lower blood loss compared to that of a commercial hemostat powder. These findings highlight the potential of applying a PDA-assisted alkaline treatment to SF fibers to efficiently create hemostatic fibers with controllable lengths, which would be promising candidates for clinical hemostatic applications.

Tilapia-Derived Granular Hydrogel as a 3D Scaffold Promoting Rapid Wound Healing

The skin, a crucial organ that protects the body, is vulnerable to external damage. Traditional tissue regeneration methods, including bulk hydrogels, aim to facilitate wound healing by interacting with host cells and providing a conducive environment. However, the nanoscale porosity of conventional hydrogels limits cell penetration and tissue regeneration. To overcome this, hydrogels composed of microgels have emerged as promising alternatives. In this study, we propose a granular hydrogel using decellularized tilapia skin. The tilapia skin-based microgels are cost-effective, immune-friendly, and have a high collagen content. Microgels based on the decellularized extracellular matrix of tilapia were successfully fabricated by using microfluidics. Through the assembly of these microgels using adhesive hyaluronic acid-catechol, the resulting 3D granular hydrogel scaffold facilitated enhanced cell growth, accelerated cell differentiation, and successful healing of full-thickness wounds in a mouse model. This study reveals the potential of tilapia skin-based granular hydrogel assembly in wound healing, overcoming conventional hydrogel limits.

Specimen Geometry Effect on Experimental Tensile Mechanical Properties of Tough Hydrogels

Synthetic tough hydrogels have received attention because they could mimic the mechanical properties of natural hydrogels, such as muscle, ligament, tendon, and cartilage. Many recent studies suggest various approaches to enhance the mechanical properties of tough hydrogels. However, directly comparing each hydrogel property in different reports is challenging because various testing specimen shapes/sizes were employed, affecting the experimental mechanical property values. This study demonstrates how the specimen geometry-the lengths and width of the reduced section-of a tough double-network hydrogel causes differences in experimental tensile mechanical values. In particular, the elastic modulus was systemically compared using eleven specimens of different shapes and sizes that were tensile tested, including a rectangle, ASTM D412-C and D412-D, JIS K6251-7, and seven customized dumbbell shapes with various lengths and widths of the reduced section. Unlike the rectangular specimen, which showed an inconsistent measurement of mechanical properties due to a local load concentration near the grip, dumbbell-shaped specimens exhibited a stable fracture at the reduced section. The dumbbell-shaped specimen with a shorter gauge length resulted in a smaller elastic modulus. Moreover, a relationship between the specimen dimension and measured elastic modulus value was derived, which allowed for the prediction of the experimental elastic modulus of dumbbell-shaped tough hydrogels with different dimensions. This study conveys a message that reminds the apparent experimental dependence of specimen geometry on the stress-strain measurement and the need to standardize the measurement of of numerous tough hydrogels for a fair comparison.

On-Demand Macroscale Delivery System Based on a Macroporous Cryogel with a High Drug Loading Capacity for Enhanced Cancer Therapy

The macroscale delivery system has been one of the practical platforms for a controlled delivery system by acting as a local depot close to the target tissue. In this study, we fabricated a macroporous alginate crygel incorporated with gold nanorods (GNRs) for the on-demand release of a chemotherapeutic drug from macroscale materials placed beside the target tumor. The macroporous crygel was prepared by the ice-crystal templating of a covalently crosslinked alginate hydrogel incorporated with GNRs. Mitoxantrone (MX), one of the potent anticancer drugs with a positive charge, was strongly adsorbed on the negative alginate chains of the cryogels. This system enabled a high loading of MX and a successful on-demand release of strongly bound MX from the GNR-loaded macroporous cryogels by near-infrared (NIR) irradiation by the dissociation of the interaction between the alginate backbone and MX. Cell viability after the NIR irradiation of the MX-loaded macroporous cryogel was significantly lower compared to that under no stimuli conditions. The in vivo test showed that repetitive NIR irradiations on the MX-loaded cryogel implanted near the tumor suppressed the tumor volume six times more than that of the control group. This simple approach to fabricate a macroporous cryogel capable of the on-demand release of bioactive cargos could be beneficial in various applications including cell, gene, and the other small molecule delivery systems.

Fabrication of cell-benign inverse opal hydrogels for three-dimensional cell culture

Inverse opal hydrogels (IOHs) for cell culture were fabricated and optimized using calcium-crosslinked alginate microbeads as sacrificial template and gelatin as a matrix. In contrast to traditional three-dimensional (3D) scaffolds, the gelatin IOHs allowed the utilization of both the macropore surface and inner matrix for cell co-culture. In order to remove templates efficiently for the construction of 3D interconnected macropores and to maintain high cell viability during the template removal process using EDTA solution, various factors in fabrication, including alginate viscosity, alginate concentration, alginate microbeads size, crosslinking calcium concentration, and gelatin network density were investigated. Low viscosity alginate, lower crosslinking calcium ion concentration, and lower concentration of alginate and gelatin were found to obtain high viability of cells encapsulated in the gelatin matrix after removal of the alginate template by EDTA treatment by allowing rapid dissociation and diffusion of alginate polymers. Based on the optimized fabrication conditions, gelatin IOHs showed good potential as a cell co-culture system, applicable to tissue engineering and cancer research.

Single exposure to heat induces stage-specific germ cell apoptosis in rats: role of intratesticular testosterone on stage specificity

Short term exposure of the testis to heat causes degeneration of germ cells. However, the mechanisms underlying this process are poorly understood. The major objectives of this study were to determine whether the heat-induced loss of germ cells in the adult rat occurs via apoptosis, to document its stage-specific and cell-specific distribution, and to examine whether intratesticular testosterone (T) plays any role in the stage specificity of heat-induced germ cell death. Testes of adult male Sprague-Dawley rats were exposed to 22 C (control) or 43 C for 15 min. Animals were killed on days 1, 2, 9, and 56 after heat exposure. Germ cell apoptosis was characterized by DNA gel electrophoresis and in situ terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick end labeling assay. The incidence of germ cell apoptosis [apoptotic index (AI)] was quite low in control rats (AI = 0.04-0.1). Mild hyperthermia within 1 or 2 days resulted in a marked activation (AI = 4.7-5.6) of germ cell apoptosis predominantly at early (I-IV) and late (XII-XIV) stages. Stages V-VI and VII-VIII were relatively protected from heat-induced apoptosis. Spermatocytes, including pachytenes at stages I-IV and IX-XII, diplotene and dividing spermatocytes at stages XIII-XIV, and early (steps 1-4) spermatids, were most susceptible to heat. On day 9, the majority of the tubules were severely damaged and displayed only a few remaining apoptotic germ cells. By day 56, spermatogenesis was completely recovered, and the incidence of germ cell apoptosis was compatible with the control levels. To determine whether intratesticular T plays a role in protecting germ cells at stages VII-VIII against heat-induced cell death, adult rats were exposed to local testicular heating on day 2 or were given a daily sc injection of GnRH antagonist (GnRH-A) for 4 days with and without a single exposure of testes to heat applied on day 2. By day 4, the incidence of increased germ cell apoptosis at stages other than VII-VIII were not different between heat-treated and GnRH-A- plus heat-treated groups, whereas the control group and the group treated with GnRH-A alone showed minimal apoptosis. GnRH-A addition to heat resulted in a further increase in apoptosis (by 3.2-fold) at stages VII-VIII over the values measured in the heat-treated group, and it became comparable to that at all other stages. Collectively, these results provide evidence that 1) heat induces germ cell apoptosis in a stage-specific and cell-specific fashion; and 2) intratesticular T plays a pivotal role in protecting germ cells at stages VII-VIII against heat-induced cell death. However, the possible involvement of various other factors, including growth factors, thermoprotectants, cytokines, and various death-related proteins, in protecting germ cells against heat-induced apoptosis cannot be ruled out.

The dental caries experience, oral hygiene and dietary practices of preschool children of factory workers in Phnom Penh, Cambodia

Two hundred and thirty-seven children attending four Ministry of Industry nursery schools in Phnom Penh, Cambodia, were examined. Dental caries experience, oral cleanliness and soft tissue abnormalities were determined. 149 mothers of these children were interviewed and information was gathered about infant-feeding practices, weaning age, diet after weaning, toothbrushing and dental attendance. Dental caries experience was high, and only 36% of children aged 1-4 years and 4% of those aged 5-6 years were caries free. Only 15% of mothers reported bottle-feeding, but 70% of these used sweetened canned milk in the bottle. Oral hygiene was rated as poor in 80% of children and only 10% were reported to use a toothbrush. 43% of children were reported to have experienced toothache, but only 5% had been to a dentist.

Buserelin in a superovulatory regimen for Holstein cows. I. Pituitary and ovarian hormone response in an experimental herd

Two experiments were conducted with frequent blood sampling in standard superovulatory regimens using follicle stimulating hormone (FSH) and prostaglandin F(2) alpha (PGF) to study the effects of the gonadotropin releasing hormone analog, Buserelin, on changes in FSH, luteinizing hormone (LH), progesterone (P(4)) and estradiol (E(2)). In Experiment I, Buserelin (20 mug) was administered to a total of 28 dry Holsteins. One group was treated with Buserelin 36 and 60 h after PGF administration, a second group was treated 60 h after PGF, and a third group served as the controls. In Experiment II, 30 dry Holsteins received Buserelin (10 mug). One group was treated 48 h after PGF, a second group at 54 h after PGF, a third group 24 h after estrus was first observed and a fourth group was a control. The general pattern of a decrease in P(4) following PGF, an increase in E(2), the onset of estrus, an LH peak, and finally, an increase in P(4) in superovulated cows was observed. Buserelin consistently produced a sharp LH peak at 36 h when given 36 h after PGF. At later intervals, it produced either a major or minor peak depending upon whether a spontaneous LH peak had already occurred. There was too much individual cow variation in the interval from PGF to a spontaneous LH peak to consistently induce a uniform LH peak, except when Buserelin was given 36 h after PGF, which may be early for normal oocyte maturation. There was no treatment effect on FSH, and embryo recovery rate was unaffected by treatment (P>0.05).