Protecting phytase from food processing stress using acid-resistant core-shell hydrogel carriers.

We demonstrate that when using cell-laden core-shell hydrogel beads to support the generation of tumor spheroids, the shell structure reduces the out-of-bead and monolayer cell proliferation that occurs during long-term culture of tumor cells within core-only alginate beads. We fabricate core-shell beads in a two-step process using simple, one-layer microfluidic devices. Tumor cells encapsulated within the bead core will proliferate to form multicellular aggregates which can serve as three-dimensional (3-D) models of tumors in drug screening. Encapsulation in an alginate shell increased the time that cells could be maintained in three-dimensional culture for MCF-7 breast cancer cells prior to out-of-bead proliferation, permitting formation of spheroids over a period of 14 days without the need move the cell-laden beads to clean culture flasks to separate beads from underlying monolayers. Tamoxifen and docetaxel dose response shows decreased toxicity for multicellular aggregates in three-dimensional core-shell bead culture compared to monolayer. Using simple core-only beads gives mixed monolayer and 3-D culture during drug screening, and alters the treatment result compared to the 3-D core-shell or the 2-D monolayer groups, as measured by standard proliferation assay. By preventing the out-of-bead proliferation and subsequent monolayer formation that is observed with core-only beads, the core-shell structure can obviate the requirement to transfer the beads to a new culture flask during drug screening, an important consideration for cell-based drug screening and drugs which have high multicellular resistance index.

Ionically cross-linked alginate-chitosan core-shell hydrogel beads for oral delivery of insulin

Longan-inspired chitosan-pectin core-shell hydrogel beads for oral delivery of biodrugs to enhance osteoporosis therapy.

Effect of inulin on structural, physicochemical, and in vitro gastrointestinal tract release properties of core-shell hydrogel beads as a delivery system for vitamin B12

Mangiferin loaded carrageenan/chitosan core-shell hydrogel beads: Preparation, characterization and proposed application

The prevalence of gastric disorders in high-performance horses, especially gastric ulceration, ranges from 50 to 90%. These pathological conditions have negative impacts on athletic performance and health. This study was designed to evaluate changes in gastric pH during a 24 h period and to compare gastrin concentrations at different time points in horses undergoing general inhalation anesthesia and dorsal recumbency. Twenty-two mixed-breed mares weighing 400 ± 50 kg and aged 8 ± 2 years were used. Of these, eight were fasted for 8 h and submitted to 90 min of general inhalation anesthesia in dorsal recumbency. Gastric juice samples were collected prior to anesthesia (T0), and then at 15 min intervals during anesthesia (T15-T90). After recovery from anesthesia (45 ± 1 min), samples were collected every hour for 24 h (T1 to T24) for gastric juice pH measurement. During this period, mares had free access to Bermuda grass hay and water and were fed a commercial concentrate twice (T4 and T16). In a second group (control), four non-anesthetized mares were submitted to 8 h of fasting followed by nasogastric intubation. Gastric juice samples were then collected at T0, T15, T30, T45, T60, T75, and T90. During this period, mares did not receive food or water. After 45 min, mares had free access to Bermuda grass hay and water, and gastric juice samples were collected every hour for four hours (T1 to T4). In a third group comprising ten non-fasted, non-anesthetized mares with free access to Bermuda grass hay and water, gastric juice samples were collected 30 min after concentrate intake (T0). In anesthetized mares, blood gastrin levels were measured prior to anesthesia (8 h fasting; baseline), during recovery from anesthesia, and 4 months after the anesthetic procedure, 90 min after the morning meal. Mean values of gastric juice pH remained acidic during general anesthesia. Mean pH values were within the physiological range (4.52 ± 1.69) and did not differ significantly between time points (T15-T90; p > 0.05). After recovery from anesthesia, mean gastric pH values increased and remained in the alkaline range throughout the 24 h period of evaluation. Significant differences were observed between T0 (4.88 ± 2.38), T5 (7.08 ± 0.89), T8 (7.43 ± 0.22), T9 (7.28 ± 0.36), T11 (7.26 ± 0.71), T13 (6.74 ± 0.90), and T17 (6.94 ± 1.04) (p < 0.05). The mean gastric juice pH ranged from weakly acidic to neutral or weakly alkaline in all groups, regardless of food and water intake (i.e., in the fasted, non-fasted, and fed states). Mean gastric pH measured in the control group did not differ from values measured during the 24 h post-anesthesia period or in the non-fasted group. Gastrin concentrations increased significantly during the post-anesthetic period compared to baseline (20.15 ± 7.65 pg/mL and 15.15 ± 3.82 pg/mL respectively; p < 0.05). General inhalation anesthesia and dorsal recumbency did not affect gastric juice pH, which remained acidic and within the physiological range. Gastric juice pH was weakly alkaline after recovery from anesthesia and in the fasted and fed states. Serum gastrin levels increased in response to general inhalation anesthesia in dorsal recumbency and were not influenced by fasting. Preventive pharmacological measures are not required in horses submitted to general anesthesia and dorsal recumbency.

Improving the thermal stability of phytase using core-shell hydrogel beads

Al-Masri, M.R. 2006. Productive performance and digestive tract size of broiler chicks fed a conventional or an all vegetable ingredients diet. J. Appl. Anim. Res., 30: 81–84. Experiments were carried out to study the effect of feeding broiler chicks with added meat-bone meal (conventional diet) or without (vegetable diet) on feed efficiency (FE), metabolizable energy efficiency (MEE) and biological aspects of digestive organs during 1–53 days of chicks' age. The two diets had no significant (P<0.05) effects on FE and MEE. The FE values were positively correlated to the metabolizable energy consumption values (R=0.77). Changing from a diet containing meat-bone meal to an all vegetable ingredients had no negative effect on the biological aspects of broilers' digestive tract (relative weights of crop, proventriculus, gizzard, duodenum, jejunum, ileum, caeca, colon, pancreas and liver). An all vegetable diet is recommended for broiler production.

The ability to trigger a destabilization of the membrane integrity of liposomes bound to environmentally sensitive hydrophobically modified core-shell hydrogel beads is demonstrated. Hydrogel beads with a core composed of poly(N-isopropylacrylamide) lightly cross-linked with bisacrylamide (BA) (pNIPAM) and a shell composed of NIPAM highly cross-linked with BA and containing varying amounts of acrylic acid (AA) [p(NIPAM-co-AA)] undergo a volume phase transition (VPT) at approximately 32 degrees C, as determined from (1)H magic angle spinning (MAS) NMR, regardless of the AA content of the shell. When the shell was hydrophobically modified with either decylamine or tetradecylamine, binding of extruded large unilamellar vesicles (eLUVs) composed of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) was quantitative, as determined via fluorescence spectroscopy. Fluorescence microscopy showed that such bound eLUVs did not fuse. Hydrogel-bound eLUV membrane permeability was assessed using (31)P MAS NMR in the presence of the chemical shift agent praseodymium and demonstrated that only at lower degrees of hydrophobic modification of the core-shell hydrogels was eLUV membrane barrier integrity maintained when T < VPT. At a low degree of hydrophobic modification, cycling the temperature above the VPT even for short periods caused the eLUV membranes to become leaky. Hence, eLUV membrane permeability was coupled to the hydrogel VPT, a situation that would be useful in applications requiring triggered release of liposomal contents.

Fabrication of core–shell beads, hollow capsules, and AuNP-embedded catalytic beads from an ultrasmall peptide hydrogel

Gastric tonometry and direct intraabdominal pressure monitoring in abdominal compartment syndrome

Coordination of hydralazine with Cu2+ at acidic pH promotes its oxidative degradation at neutral pH

Creating multicellular tumor spheroids is critical for characterizing anticancer treatments since they may provide a better model of the tumor than conventional monolayer culture. Moreover, tumor cell interaction with the extracellular matrix can determine cell organization and behavior. In this work, a microfluidic system was used to form cell-laden core-shell beads which incorporate elements of the extracellular matrix and support the formation of multicellular spheroids. The bead core (comprising a mixture of alginate, collagen, and reconstituted basement membrane, with gelation by temperature control) and shell (comprising alginate hydrogel, with gelation by ionic crosslinking) were simultaneously formed through flow focusing using a cooled flow path into the microfluidic chip. During droplet gelation, the alginate acts as a fast-gelling shell which aids in preventing droplet coalescence and in maintaining spherical droplet geometry during the slower gelation of the collagen and reconstituted basement membrane components as the beads warm up. After droplet gelation, the encapsulated MCF-7 cells proliferated to form uniform spheroids when the beads contained all three components: alginate, collagen, and reconstituted basement membrane. The dose-dependent response of the MCF-7 cell tumor spheroids to two anticancer drugs, docetaxel and tamoxifen, was compared to conventional monolayer culture.

Thermally induced core-shell type hydrogel beads having interpenetrating polymer network (IPN) structure

Objectives:Laparoscopic surgery (LS) is a safe and widely used technique. During LS, carbon dioxide insufflation may produce significant hemodynamic and ventilatory consequences, such as elevated intra-abdominal pressure (IAP) and hypercarbia. Splanchnic and cardiovascular blood flow can be affected by the elevated IAP, which can result in ischemia in the splanchnic region prior to hemodynamic changes. Changes in gastric pH may be an early precursor of changes in splanchnic blood circulation. This study investigated the relationship between gastric pH measurement and IAP in patients undergoing LS.Methods:This study included 49 patients aged 18–65 years with American Society of Anesthesiologists (ASA) physical status I – III who were undergoing elective laparoscopic cholecystectomy. A gastric pH tonometer probe was applied using an orogastric catheter. Simultaneously, insufflation pressure, cardiac apex beat (CAB), and mean arterial blood pressure (MAP) values were recorded. Indirect IAP was then measured through the bladder. Measurements were performed at baseline; at 15, 30, and 60 minutes after onset of insufflation (AI 15, AI 30, and AI 60, respectively); and at the end of insufflation (EI). Two pH measurements were obtained with a gastric tonometer pH probe, using an automated function of the gastric tonometer to improve measurement reliability.Results:IAP was significantly higher than baseline at AI 15, AI 30, AI 60, and EI (p<0.001). The pH1 and pH2 levels were significantly lower at AI 15 and AI 30, compared with baseline (p<0.001). There were no significant differences between pH1 and pH2 measurements at AI 60 and EI. Compared with baseline, CAB was significantly lower at AI 15, AI 30, AI 60, and EI (p=0.001, p<0.001, p=0.006). There were no statistically significant differences in MAP changes at any time point.Conclusion:Elevated IAP caused by CO2 insufflation during LS led to reductions of pH1 and pH2. There was a correlation between gastric pH measurement and IAP. Measurement of gastric pH may be useful to assess blood circulation in the splenic area during LS.