Synthesis, physicochemical characterization, and cytocompatibility of bioresorbable, dual-gelling injectable hydrogels.

Injectable, dual-gelling hydrogels were successfully developed through the combination of physical thermogellation at 37 °C and favorable amine:epoxy chemical cross-linking. Poly(N-isopropylacrylamide)-based thermogelling macromers with a hydrolyzable lactone ring and epoxy pendant groups and a biodegradable diamine-functionalized polyamidoamine cross-linker were synthesized, characterized, and combined to produce nonsyneresing and bioresorbable hydrogels. Differential scanning calorimetry and oscillatory rheometry demonstrated the rapid and dual-gelling nature of the hydrogel formation. The postgelation dimensional stability, swelling, and mechanical behavior of the hydrogel system were shown to be easily tuned in the synthesis and formulation stages. The leachable products were found to be cytocompatible under all conditions, while the degradation products demonstrated a dose- and time-dependent response due to solution osmolality. Preliminary encapsulation studies showed mesenchymal stem cell viability could be maintained for 7 days. The results suggest that injectable and thermally and chemically cross-linkable hydrogels are promising alternatives to prefabricated biomaterials for tissue engineering applications, particularly for cell delivery.

The photochemical determinants of color vision: revealing how opsins tune their chromophore's absorption wavelength.

The evolution of a variety of important chromophore-dependent biological processes, including microbial light sensing and mammalian color vision, relies on protein modifications that alter the spectral characteristics of a bound chromophore. Three different color opsins share the same chromophore, but have three distinct absorptions that together cover the entire visible spectrum, giving rise to trichromatic vision. The influence of opsins on the absorbance of the chromophore has been studied through methods such as model compounds, opsin mutagenesis, and computational modeling. The recent development of rhodopsin mimic that uses small soluble proteins to recapitulate the binding and wavelength tuning of the native opsins provides a new platform for studying protein-regulated spectral tuning. The ability to achieve far-red shifted absorption in the rhodopsin mimic system was attributed to a combination of the lack of a counteranion proximal to the iminium, and a uniformly neutral electrostatic environment surrounding the chromophore.

Identification of the SPLUNC1 ENaC-inhibitory domain yields novel strategies to treat sodium hyperabsorption in cystic fibrosis airway epithelial cultures.

The epithelial sodium channel (ENaC) is responsible for Na(+) and fluid absorption across colon, kidney, and airway epithelia. Short palate lung and nasal epithelial clone 1 (SPLUNC1) is a secreted, innate defense protein and an autocrine inhibitor of ENaC that is highly expressed in airway epithelia. While SPLUNC1 has a bactericidal permeability-increasing protein (BPI)-type structure, its NH2-terminal region lacks structure. Here we found that an 18 amino acid peptide, S18, which corresponded to residues G22-A39 of the SPLUNC1 NH2 terminus inhibited ENaC activity to a similar degree as full-length SPLUNC1 (∼2.5 fold), while SPLUNC1 protein lacking this region was without effect. S18 did not inhibit the structurally related acid-sensing ion channels, indicating specificity for ENaC. However, S18 preferentially bound to the ßENaC subunit in a glycosylation-dependent manner. ENaC hyperactivity is contributory to cystic fibrosis (CF) lung disease. Unlike control, CF human bronchial epithelial cultures (HBECs) where airway surface liquid (ASL) height was abnormally low (4.2 ± 0.6 µm), addition of S18 prevented ENaC-led ASL hyperabsorption and maintained CF ASL height at 7.9 ± 0.6 µm, even in the presence of neutrophil elastase, which is comparable to heights seen in normal HBECs. Our data also indicate that the ENaC inhibitory domain of SPLUNC1 may be cleaved away from the main molecule by neutrophil elastase, suggesting that it may still be active during inflammation or neutrophilia. Furthermore, the robust inhibition of ENaC by the S18 peptide suggests that this peptide may be suitable for treating CF lung disease.

Spinal magnetic resonance imaging with reduced specific absorption rate in patients harbouring a spinal cord stimulation device - A single-centre prospective study analysing safety, tolerability and image quality.

BACKGROUND: Spinal cord stimulation (SCS) is an accepted treatment in patients with failed back surgery (FBS), complex regional pain syndrome (CRPS) and persistent radicular pain following surgery. In order to avoid patient hazards or device malfunction manufacturers advise to abstain from magnetic resonance imaging (MRI) in patients with implanted electrodes or pulse generators. METHODS: In a prospective study, 13 patients harbouring an implanted Medtronic Spinal Cord Stimulation (SCS) device underwent MRI (1.5 T) of the lumbar (n=13), the cervical (n=2) or the thoracic spine (n=1) following the development of new spinal symptoms. An adapted MRI protocol was used limiting the transmitted energy and specific absorption rate. Tolerability and safety were assessed by means of a standardized patient evaluation form documenting pain on a visual analogue scale (0-10), neurologic deficit, and discomfort during the scan. In addition, overall satisfaction with the examination procedure was rated on a Likert scale (1-5). Image quality was rated independently and blinded to the presence of a SCS device by the radiologist and the surgeon as equivalent, superior or inferior compared to the standard spine MRI examination. RESULTS: None of the 13 patients investigated by the modified spinal MRI protocol experienced new neurological deficits, worsening of symptoms or a defect/malfunction of the implant device. Three patients (23.1 %) reported transient warm sensation in the location of the electrode and in one case intermittent slight tingling in the lower extremities. Overall satisfaction with the examination was 1.13 ± 0.34 according to Likert scale (1-5). The image quality was rated - not statistically significant - slightly inferior to standard lumbar spine imaging (0.82 ± 0.54) with a kappa value of 0.68 between the two investigators. MRI examinations detected relevant and new lesions in 9 (69.2 %) patients which affected treatment in 8 (61.5 %) individuals. CONCLUSION: Using a protocol with a reduced specific energy absorption rate, spinal MRI examinations in patients with SCS can be considered safe. The current view that neurostimulators are a general contraindication to MR examinations has to be reconsidered in patients with new or progressive spinal symptoms.

Nuevo método espectrofotométrico para la estimación de olmesartán medoxomilo en forma de dosificación comprimido usando la solubilización isotrópica / Novel Spectrophotometric Method for Estimation of Olmesartan Medoxomil from its Tablet Dosage Form Using Hydrotropic Solubilization

Objetivo: La estimación cuantitativa de fármacos poco solubles en agua implica el uso de disolventes orgánicos. En la presente investigación, se emplea la solubilización hidrotrópica para mejorar las solubilidades acuosas fármacos poco solubles en agua como el olmesartán medoxomilo dosificado en comprimido. Material y Métodos: Este método emplea acetato sódico 0,05 M como agente solubilizante hidrotrópico, mostrando el olmesartán medoxomilo una absorbancia máxima a 256 nm. La solución de acetato 0.05 M no muestra ninguna interferencia con la longitud de onda de muestreo. El agente hidrotrópico y los aditivos utilizados en la elaboración de los comprimidos no interfieren en el análisis. Resultados y conclusiones: El fármaco obedece a la Ley de Beer en el intervalo de concentraciones 2-14 mg / ml con un de coeficiente de correlación de 0,9987. El método desarrollado fue validado estadísticamente siguiendo las directrices ICH Q2B (R1). El análisis estadístico demostró que el método era sencillo y rápido para la estimación de olmesartán medoxomilo y se puede utilizar para análisis de rutina de olmesartán medoxomilo en laboratorios de control de calidad (AU)

Aim: Quantitative estimation of poorly water-soluble drugs involves use of organic solvents. In the present investigation, hydrotropic solubilization is employed to enhance the aqueous solubilities of poorly water-soluble drugs like Olmesartan Medoxomil in tablet dosage forms.Material and methods: This method utilizes 0.05 M Sodium acetate solution as hydrotropic solubilizing agent Where Olmesartan Medoxomil shows maximum absorbance at 256 nm. The 0.05 M Sodium acetate solution does not show any interference with the sampling wavelength. The hydrotropic agent and additives used in the manufacture of tablets did not interfere in the analysis. Results and Conclusion: The drug obeys the Beer’s Law in the concentration range 2-14 μg/ml with correlation coefficient value of 0.9987. The developed reliable method was validated statistically following ICH Q2B (R1) guidelines. Statistical analysis proved that the method was simple and rapid for the estimation of Olmesartan Medoxomil and can be used for routine analysis of Olmesartan Medoxomil in quality control laboratories. The ex vivo mucoadhesion time of patches ranged between 109 min (FA10) to 126 min (FB14). The ex vivo mucoadhesive force was in the range of 0.278 to 0.479 Kg.m.s-2. The in vitro drug release studies revealed that formulation FA8 released 84% and FB16 released 99.01% of drug in 140 min (AU)

Feed restriction reduces short-chain fatty acid absorption across the reticulorumen of beef cattle independent of diet.

The objective of this study was to evaluate the effects of the forage-to-concentrate ratio (F:C) of diets fed before and during short-term feed restriction (FR) on rumen fermentation, absorptive capacity of the reticulorumen, and apparent total tract digestibility. Twenty ovariectomized and ruminally cannulated Angus × Hereford heifers were blocked by BW and individually penned in box stalls (9 m(2)), having free access to water throughout the study. Heifers were randomly assigned to 1 of 2 dietary treatments, receiving either a high forage diet (HF; F:C of 92:8) or a moderate forage diet (MF; F:C of 60:40). Diets were fed ad libitum for 14 d before 5 d of baseline measurements (BASE) followed by 5 d of FR where heifers were restricted to 25% of ad libitum DMI relative to BASE. Dry matter intake was measured daily and ruminal pH was recorded every 2 min throughout the study. Ruminal fluid and blood samples were collected on d 3 of BASE and FR whereas short-chain fatty acid (SCFA) absorption was assessed in vivo using the isolated washed reticulorumen technique on d 5 of BASE and FR. Indigestible NDF was used as a marker to estimate apparent total tract digestibility. Diet × period interactions (P = 0.030 and 0.025) were detected for DMI and ruminal SCFA concentration, respectively. The interaction was the result of greater DMI and numerically greater SCFA concentration for MF than HF during BASE, with a reduction observed for both during FR, although treatment effects were no longer present. Period effects (BASE vs. FR) but not treatment effects (P > 0.05) were detected for mean ruminal pH (P < 0.001) and the total SCFA absorption rate (mmol/h; P = 0.038). During BASE, mean pH was reduced (6.4 vs. 6.9) and the SCFA absorption rate was greater relative to FR (674.5 vs. 554.8 mmol/h). Diet (P < 0.001) and period (P < 0.001) effects were detected for DM and OM digestibility with greater digestibility occurring for heifers fed MF than HF (70.5 vs. 63.3% for DM and 73.0 vs. 66% for OM) and greater digestibility during FR than BASE (69.5 vs. 64.3% for DM and 71.7 vs. 67.2% for OM). During FR, NDF digestibility was also greater than during BASE (P < 0.001; 62.4 vs. 55.8%). The effect of FR on serum NEFA differed by diet (diet × period, P < 0.001) with NEFA being greater for heifers fed HF than MF during FR (474.4 vs. 377.7 µEq/mL, respectively) with no differences observed between HF and MF during BASE. It can be concluded that severe short-term FR had a negative impact on ruminal SCFA absorption and energy balance and that altering the F:C of the diet does not mitigate these effects.

Importance of lipid microdomains, rafts, in absorption, delivery, and biological effects of resveratrol.

The preventive effects of the phytoalexin trans-resveratrol toward cancer have been largely described at the cellular and molecular levels in both in vivo and in vitro models; however, its primary targets are still poorly identified. In this review, we show the crucial role of cell membrane microdomains, that is, lipid rafts, not solely in the initiation of the early biochemical events triggered by resveratrol leading to cancer cell death, but also in resveratrol absorption and distribution. Resveratrol accumulates in lipid rafts and is then taken up by cells through raft-dependent endocytosis. These events allow early activation of kinase pathways and redistribution of cell death receptors within lipid microdomains, events ultimately leading to apoptotic cell death.

Nonlinear absorption kinetics of self-emulsifying drug delivery systems (SEDDS) containing tocotrienols as lipophilic molecules: in vivo and in vitro studies.

Self-emulsifying drug delivery systems (SEDDS) have been broadly used to promote the oral absorption of poorly water-soluble drugs. The purpose of the current study was to evaluate the in vivo oral bioavailability of vitamin E isoforms, δ-tocotrienol (δ-T3) and γ-tocotrienol (γ-T3) administered as SEDDS, as compared to commercially available UNIQUE E® Tocotrienols capsules. Results from studies in rats showed that low dose treatment with δ-T3 (90%) and γ-T3 (10%) formulated SEDDS showed bioavailability of 31.5% and 332%, respectively. However, bioavailability showed a progressive decrease with increased treatment dose that displayed nonlinear absorption kinetics. Additional in vitro studies examining cellular uptake studies in Caco 2 cells revealed that the SEDDS formulation increased passive permeability of δ-T3 and γ-T3 by threefold as compared to the commercial capsule formulation. These studies also showed that free surfactants decreased δ-T3 and γ-T3 absorption. Specifically, combined treatment cremophor EL or labrasol with tocotrienols caused a 60-85% reduction in the cellular uptake of δ-T3 and γ-T3 and these effects appear to result from surfactant-induced inhibition of the δ-T3 and γ-T3 transport protein Niemann-Pick C1-like 1 (NPC1L1). In summary, results showed that SEDDS formulation significantly increases the absorption and bioavailability δ-T3 and γ-T3. However, this effect is self-limiting because treatment with increasing doses of SEDDS appears to be associated with a corresponding increase in free surfactants levels that directly and negatively impact tocotrienol transport protein function and results in nonlinear absorption kinetics and a progressive decrease in δ-T3 and γ-T3 absorption and bioavailability.

Nitric oxide reduces Cl⁻ absorption in the mouse cortical collecting duct through an ENaC-dependent mechanism.

Since nitric oxide (NO) participates in the renal regulation of blood pressure, in part, by modulating transport of Na⁺ and Cl⁻ in the kidney, we asked whether NO regulates net Cl⁻ flux (JCl) in the cortical collecting duct (CCD) and determined the transporter(s) that mediate NO-sensitive Cl⁻ absorption. Cl⁻ absorption was measured in CCDs perfused in vitro that were taken from aldosterone-treated mice. Administration of an NO donor (10 µM MAHMA NONOate) reduced JCl and transepithelial voltage (VT) both in the presence or absence of angiotensin II. However, reducing endogenous NO production by inhibiting NO synthase (100 µM N(G)-nitro-L-arginine methyl ester) increased JCl only in the presence of angiotensin II, suggesting that angiotensin II stimulates NO synthase activity. To determine the transport process that mediates NO-sensitive changes in JCl, we examined the effect of NO on JCl following either genetic ablation or chemical inhibition of transporters in the CCD. Since the application of hydrochlorothiazide (100 µM) or bafilomycin (5 nM) to the perfusate or ablation of the gene encoding pendrin did not alter NO-sensitive JCl, NO modulates JCl independent of the Na⁺-dependent Cl⁻/HCO3⁻ exchanger (NDCBE, Slc4a8), the A cell apical plasma membrane H⁺-ATPase and pendrin. In contrast, both total and NO-sensitive JCl and VT were abolished with application of an epithelial Na(+) channel (ENaC) inhibitor (3 µM benzamil) to the perfusate. We conclude that NO reduces Cl⁻ absorption in the CCD through a mechanism that is ENaC-dependent.

Tubular reabsorption and local production of urine hepcidin-25.

BACKGROUND: Hepcidin is a central regulator of iron metabolism. Serum hepcidin levels are increased in patients with renal insufficiency, which may contribute to anemia. Urine hepcidin was found to be increased in some patients after cardiac surgery, and these patients were less likely to develop acute kidney injury. It has been suggested that urine hepcidin may protect by attenuating heme-mediated injury, but processes involved in urine hepcidin excretion are unknown. METHODS: To assess the role of tubular reabsorption we compared fractional excretion (FE) of hepcidin-25 with FE of ß2-microglobulin (ß(2)m) in 30 patients with various degrees of tubular impairment due to chronic renal disease. To prove that hepcidin is reabsorbed by the tubules in a megalin-dependent manner, we measured urine hepcidin-1 in wild-type and kidney specific megalin-deficient mice. Lastly, we evaluated FE of hepcidin-25 and ß(2)m in 19 patients who underwent cardiopulmonary bypass surgery. Hepcidin was measured by a mass spectrometry assay (MS), whereas ß(2)m was measured by ELISA. RESULTS: In patients with chronic renal disease, FE of hepcidin-25 was strongly correlated with FE of ß(2)m (r = 0.93, P <0.01). In megalin-deficient mice, urine hepcidin-1 was 7-fold increased compared to wild-type mice (p < 0.01) indicating that proximal tubular reabsorption occurs in a megalin- dependent manner. Following cardiac surgery, FE of hepcidin-25 increased despite a decline in FE of ß(2)m, potentially indicating local production at 12-24 hours. CONCLUSIONS: Hepcidin-25 is reabsorbed by the renal tubules and increased urine hepcidin-25 levels may reflect a reduction in tubular uptake. Uncoupling of FE of hepcidin-25 and ß(2)m in cardiac surgery patients suggests local production.

Recovery of absorptive function of the reticulo-rumen and total tract barrier function in beef cattle after short-term feed restriction.

Our objective was to determine if the severity of short-term feed restriction (FR) affects the timeline for recovery of the absorptive function of the reticulo-rumen and barrier function of the total gastrointestinal tract in beef cattle. Eighteen ruminally cannulated and ovariectomized Angus × Hereford heifers were housed in individual pens. Heifers were blocked by initial BW into 3 blocks and, within block, randomly assigned to 1 of 3 treatments that differed in the severity of FR: heifers were restricted to 75, 50, or 25% of ad libitum intake. Treatments were imposed during a 5-d period of FR followed by 3 consecutive wk of recovery (REC1, REC2, and REC3). Throughout the experiment heifers were fed the same diet (60% forage:40% concentrate) for ad libitum intake (except during FR) and water was available at all times. Dry matter intake was measured daily and ruminal pH was recorded every 2 min during FR and recovery periods. Ruminal fluid and blood samples were collected on d 3 of the FR and d 5 of REC1 and REC3. Short-chain fatty acid (SCFA) absorption rates were evaluated on the last day of FR, REC1, and REC3 using the temporarily isolated and washed reticulo-rumen technique. On d 2 of FR and d 4 of REC1 and REC3, a 1 L solution of Cr-EDTA (180 mM) was dosed into the rumen followed by 48 h of total urine collection. Dry matter intake (% BW) increased rapidly in REC1 for heifers restricted to 75 and 50%; however, heifers restricted to 25% needed at least 2 wk to recover (treatment × period; P < 0.001). Regardless of the severity of FR, the duration that pH < 5.5 was the highest during REC1 (period P < 0.001). However, an interaction was found for the acidosis index, with pH × min/kg of DMI being greatest in heifers restricted to 25% on d 1 of the recovery period. A treatment × period interaction was found for the absolute absorption rate (mmol/h) of total SCFA (P = 0.009). The total SCFA absorption rate was not different for heifers restricted to 75 and 50% across periods, whereas an increase from FR and REC1 to REC3 was detected for heifers restricted to 25% of ad libitum intake. A treatment effect was observed for urinary Cr output (P = 0.027) indicating that heifers previously restricted to 25% of ad libitum intake had greater Cr excretion in urine during FR and recovery. This study indicates that severe FR negatively affects the time required for recovery of reticulo-rumen absorptive function and total tract barrier function. Another important finding is that regardless of severity, FR increases risk for ruminal acidosis when heifers have free access to feed after FR.

Short-term feed restriction impairs the absorptive function of the reticulo-rumen and total tract barrier function in beef cattle.

The objective of this study was to evaluate whether different severities of short-term feed restriction (FR) affect the absorptive function of the reticulo-rumen and total tract barrier function in beef cattle. Eighteen ruminally cannulated and ovariectomized Angus × Hereford heifers were blocked by BW into 3 blocks, with blocks conducted sequentially. Treatments were imposed during the 5-d FR period by restricting heifers to 75 (FR75), 50 (FR50) or 25% (FR25) of the ad libitum feed intake measured during a 5-d baseline period (BASE) occurring immediately before FR. Throughout the study, heifers were housed in individual pens (9 m(2)) and were fed the same diet (60% forage:40% concentrate) with free access to water. Dry matter intake was measured daily and ruminal pH was measured every 2 min throughout the study. Ruminal fluid and blood samples were collected on d 3 of the BASE and FR periods, and the temporarily isolated and washed reticulo-rumen technique was used to evaluate short-chain fatty acid (SCFA) absorption on d 5 of the BASE and FR periods. Total tract barrier function was evaluated starting on d 2 of the BASE and FR periods using a pulse dose of Cr-EDTA followed by 48 h of total urine collection. Data were analyzed using the Proc Mixed procedure of SAS with the fixed effects of block, treatment, period, and the treatment × period interaction, the random effect of cow nested in block with period included as a repeated measure. Dry matter intake did not differ among treatments during BASE but, as imposed by the experimental model, DMI during FR relative to BASE equated to 70, 49, and 25%, which was close to the targeted values of 75, 50, and 25% (treatment × period, P < 0.001). A treatment × period interaction (P < 0.001) was also detected for ruminal SCFA concentration with the concentration decreasing as the severity of FR increased, whereas there were no differences during BASE. Mean ruminal pH increased during FR with increasing severity of FR, but was not different during BASE (treatment × period, P < 0.001). Absorption of SCFA across the reticulo-rumen tended to decrease with increasing severity of FR (P = 0.08). For individual SCFA, acetate absorption (mmol/h) tended (P = 0.057) to be less for FR25 and FR50 when compared with FR75 and decreased (P = 0.05) by almost 70 mmol/h at FR25 and FR50 relative to BASE (322mmol/h). Heifers restricted to 25% (FR25) feed had greater urinary Cr recovery during FR than BASE, whereas no changes were detected for FR75 and FR50. This study indicates that moderate severities of short-term FR decrease the absorptive function of the reticulo-rumen, but more severe FR is required to compromise total tract barrier function in beef cattle.

A two-hit mechanism for sepsis-induced impairment of renal tubule function.

Renal insufficiency is a common and severe complication of sepsis, and the development of kidney dysfunction increases morbidity and mortality in septic patients. Sepsis is associated with a variety of defects in renal tubule function, but the underlying mechanisms are incompletely understood. We used a cecal ligation and puncture (CLP) model to examine mechanisms by which sepsis influences the transport function of the medullary thick ascending limb (MTAL). MTALs from sham and CLP mice were studied in vitro 18 h after surgery. The results show that sepsis impairs the ability of the MTAL to absorb HCO(3)(-) through two distinct mechanisms. First, sepsis induces an adaptive decrease in the intrinsic capacity of the tubules to absorb HCO(3)(-). This effect is associated with an increase in ERK phosphorylation in MTAL cells and is prevented by pretreatment of CLP mice with a MEK/ERK inhibitor. The CLP-induced reduction in intrinsic HCO(3)(-) absorption rate appears to involve loss of function of basolateral Na(+)/H(+) exchange. Second, sepsis enhances the ability of LPS to inhibit HCO(3)(-) absorption, mediated through upregulation of Toll-like receptor 4 (TLR4)-ERK signaling in the basolateral membrane. The two inhibitory mechanisms are additive and thus can function in a two-hit capacity to impair renal tubule function in sepsis. Both effects depend on ERK and are eliminated by interventions that prevent ERK activation. Thus the TLR4 and ERK signaling pathways represent potential therapeutic targets to treat or prevent sepsis-induced renal tubule dysfunction.

Effects of feeding fermented Ginkgo biloba leaves on small intestinal morphology, absorption, and immunomodulation of early lipopolysaccharide-challenged chicks.

Aspergillus niger-fermented-Ginkgo biloba leaves (FG) and the comparative effect with nonfermented (NF)-Ginkgo leaves were investigated on morphology, absorption, and immunity of small intestine after lipopolysaccharide (LPS)-challenge in chicks at an early age. Broiler chicks (180 d of age) were divided into 3 treatment groups and were fed 1 of 3 diets: basal diet or basal diet supplemented with 0.5% NF or FG (control, NF, and FG group, respectively). Half of the birds from each treatment group were injected intraperitoneally with LPS (500 µg/kg of BW) or 0.9% NaCl solution (the sham control groups) at 10, 12, 15, 17, 19, and 21 d of age. The results indicated that when LPS-challenged birds were pretreated with FG, the decrease of ADG, ADFI, duodenal and jejunal relative weights, villus height, crypt depth, alkaline phosphatase activity, and plasma d-xylose were dramatically attenuated (P < 0.05 or P < 0.01). Meanwhile, a significant decrease (P < 0.05 or P < 0.01) of duodenal and jejunal interferon-γ, interleukin (IL)-4, IL-13, IL-18, inducible nitric oxide synthase, and duodenal sodium glucose co-transporter 1 mRNA expressional levels were found in LPS-challenged birds pretreated with FG. In conclusion, FG-supplemented diets minimized the deleterious effects of LPS and improved intestinal development, absorption, and immunity in immune-stressed chickens.

Impact attenuation during weight bearing activities in barefoot vs. shod conditions: a systematic review.

Although it could be perceived that there is extensive research on the impact attenuation characteristics of shoes, the approach and findings of researchers in this area are varied. This review aimed to clarify the effect of shoes on impact attenuation to the foot and lower leg and was limited to those studies that compared the shoe condition(s) with barefoot. A systematic search of the literature yielded 26 studies that investigated vertical ground reaction force, axial tibial acceleration, loading rate and local plantar pressures. Meta-analyses of the effect of shoes on each variable during walking and running were performed using the inverse variance technique. Variables were collected at their peak or at the impact transient, but when grouped together as previous comparisons have done, shoes reduced local plantar pressure and tibial acceleration, but did not affect vertical force or loading rate for walking. During running, shoes reduced tibial acceleration but did not affect loading rate or vertical force. Further meta-analyses were performed, isolating shoe type and when the measurements were collected. Athletic shoes reduced peak vertical force during walking, but increased vertical force at the impact transient and no change occurred for the other variables. During running, athletic shoes reduced loading rate but did not affect vertical force. The range of variables examined and variety of measurements used appears to be a reason for the discrepancies across the literature. The impact attenuating effect of shoes has potentially both adverse and beneficial effects depending on the variable and activity under investigation.

Correlation of drug release with pulmonary drug absorption profiles for nebulizable liposomal formulations.

Liposomes have attracted extensive attention as inhalative drug delivery vehicles. The preparation of tailored liposomal formulations (i.e. nebulization stability and controlled drug release profiles) would facilitate new perspectives for the treatment of pulmonary diseases. 5(6)-Carboxyfluorescein (CF)-loaded submicron liposomal formulations with varying phase transition temperatures were prepared from lipid blends in different molar ratios. Their physicochemical properties, in vitro dye release, stability to nebulization (Aeroneb Pro) and ex vivo pulmonary dye absorption and distribution characteristics were investigated. Phase transitions of liposomes were adjusted below and above body temperature (32.9-55.2 °C). The amount of CF released from liposomes in vitro correlated well with their membrane fluidity. An increase in phase transition temperature resulted in an extended dye release profile. All formulations revealed aerodynamic particle sizes of ∼4 µm with remarkable stability when nebulized by vibrating-mesh technology (percentage of encapsulated model drug ∼80%). Analogous to the release results observed in vitro, liposomal formulations revealing phase transitions above body temperature displayed an increased pulmonary CF retention in an ex vivo lung model. Consequently, an in vitro-ex vivo correlation was established, which demonstrated an excellent agreement of the dye release results with the absorption profiles observed in the biological system (R(2) ≥ 0.91). Overall, the concept of liposomal "phase transition release" is promising for controlled pulmonary drug delivery applications. The ex vivo technique enables a reliable determination of lung-specific pharmacokinetics of drug delivery vehicles, which enhances tailored carrier preparation and testing during early formulation development.

Kidney-specific WNK1 regulates sodium reabsorption and potassium secretion in mouse cortical collecting duct.

Kidney-specific with-no-lysine kinase 1 (KS-WNK1) is a kinase-deficient variant of WNK1 that is expressed exclusively in the kidney. It is abundantly expressed in the distal convoluted tubule (DCT) and to a lesser extent in the cortical thick ascending limb (cTAL), connecting tubule, and cortical collecting duct (CCD). KS-WNK1 inhibits Na(+)-K(+)-2Cl(-)- and sodium chloride cotransporter-mediated Na(+) reabsorption in cTAL and DCT, respectively. Here, we investigated the role of KS-WNK1 in regulating Na(+) and K(+) transport in CCD using in vitro microperfusion of tubules isolated from KS-WNK1 knockout mice and control wild-type littermates. Because baseline K(+) secretion and Na(+) reabsorption were negligible in mouse CCD, we studied tubules isolated from mice fed a high-K(+) diet for 2 wk. Compared with that in wild-type tubules, K(+) secretion was reduced in KS-WNK1 knockout CCD perfused at a low luminal fluid rate of ~1.5 nl/min. Na(+) reabsorption and the lumen-negative transepithelial potential difference were also lower in the KS-WNK1 knockout CCD compared with control CCD. Increasing the perfusion rate to ~5.5 nl/min stimulated K(+) secretion in the wild-type as well as knockout CCD. The magnitudes of flow-stimulated increase in K(+) secretion were similar in wild-type and knockout CCD. Maxi-K(+) channel inhibitor iberiotoxin had no effect on K(+) secretion when tubules were perfused at ~1.5 nl/min, but completely abrogated the flow-dependent increase in K(+) secretion at ~5.5 nl/min. These findings support the notion that KS-WNK1 stimulates ROMK-mediated K(+) secretion, but not flow-dependent K(+) secretion mediated by maxi-K(+) channels in CCD. In addition, KS-WNK1 plays a role in regulating Na(+) transport in the CCD.

OSR1-sensitive renal tubular phosphate reabsorption.

BACKGROUND: The oxidative stress-responsive kinase 1 (OSR1) participates in the WNK-(with no K) kinase dependent regulation of renal salt excretion and blood pressure. Little is known, however, about the role of OSR1 in the regulation of further renal transport systems. The present study analyzed the effect of OSR1 on NaPiIIa, the major renal tubular phosphate transporter. METHODS: Immunohistochemistry and confocal microscopy were employed to determine renal localization of OSR1 and NaPiIIa. To elucidate the effect of OSR on NaPiIIa activity, cRNA encoding NaPiIIa was injected into Xenopus oocytes with or without additional injection of cRNA encoding OSR1, and phosphate transport was estimated from phosphateinduced currents determined with dual electrode voltage clamp. To elucidate the in vivo significance of OSR1 serum phosphate and hormone concentrations as well as urinary phosphate output of mice carrying one allele of WNK-resistant OSR1 (osr1tg/(+)) were compared to the respective values of wild type mice (osr1(+/+)). RESULTS: NaPiIIa and OSR1 were both expressed in proximal renal tubule cells. Coexpression of OSR1 significantly up-regulated phosphate-induced currents in NaPiIIa-expressing Xenopus oocytes. Despite decreased serum phosphate concentration urinary phosphate excretion was significantly increased and NaPiIIa protein abundance in the brush border membrane significantly reduced in osr1tg/(+) mice as compared to osr1(+/+) mice. Serum PTH and calcitriol levels were similar in osr1tg/(+) mice and in osr1(+/+) mice, serum FGF23 concentration was, however, significantly higher in osr1tg/(+) mice than in osr1(+/+) mice. CONCLUSIONS: OSR1 is expressed in proximal renal tubules and participates in the regulation of FGF23 release and renal tubular phosphate transport.

Effect of abomasal emptying rate on the apparent efficiency of colostral immunoglobulin G absorption in neonatal Holstein-Friesian calves.

Inadequate absorption of colostral IgG in calves increases the risk of morbidity and death and is an important source of economic loss to the dairy industry. We hypothesized that an increased rate of abomasal emptying in colostrum-fed calves would be associated with an increased apparent efficiency of absorption (AEA) of colostral IgG. This is because an increase in abomasal emptying rate causes IgG to reach the site of absorption in the small intestine earlier and at a higher luminal concentration. The main objective was, therefore, to determine the association between the AEA of colostral IgG and abomasal emptying rate in neonatal calves. Twenty-four neonatal Holstein-Friesian calves were randomly assigned to one of the following treatments: control, 2 mL of 0.9% NaCl intramuscularly; erythromycin, 8.8 mg/kg of body weight intramuscularly; ivermectin, 200 µg/kg intravenously; and gentamicin, 6.6 mg/kg intramuscularly. These treatments were selected because we have previously demonstrated that erythromycin and ivermectin increase, and gentamicin decreases, the rate of abomasal emptying in milk-fed calves. Calves were fed 3 L of pooled cow colostrum containing acetaminophen (50mg/kg of body weight) by oroesophageal intubation at 1h of age and 30 min after each treatment was administered. Jugular venous blood samples were obtained periodically after the start of feeding. Abomasal emptying rate was assessed by the time to maximal plasma acetaminophen concentration. Erythromycin increased and gentamicin decreased the abomasal emptying rate and AEA of colostral IgG compared with control, respectively, whereas ivermectin had no effect. Using data from all 24 calves, the AEA of colostral IgG was linearly and negatively associated with abomasal emptying rate (R(2)=0.22). We conclude that the abomasal emptying rate is an important determinant of the AEA of colostral IgG. Identifying a non-antimicrobial method for increasing abomasal emptying rate will provide a practical and effective method for facilitating transfer of passive immunity in colostrum-fed dairy calves.