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Background Low dietary fiber intake has been shown to disturb the gut microbiome community, damage the mucus barrier, and promote pathogen susceptibility. However, little is known about the temporal response of the gut microbiome to dietary fiber deprivation and the recovery induced by dietary fiber inclusion in pigs. Objective In the present study, temporal responses of ileal and fecal microbiota to dietary fiber deprivation were profiled using an ileum cannulated growing pig model. In addition, the potential of dietary-resistant starch, β-glucan, and xylan to alleviate gut dysbiosis throughout the gastrointestinal tract, as well as its possible mechanisms were investigated. Methods Six cannulated growing pigs were fed a fiber deprivation diet for 35 days. Ileal digesta and feces were collected at days 0, 7, 21, and 35 for 16S rRNA sequencing and short-chain fatty acid (SCFA) determination. Another twenty-four healthy growing pigs were assigned to one of four dietary treatments including (1) fiber-free diet, (2) resistant starch diet, (3) β-glucan diet, and (4) xylan diet. These twenty-four pigs were fed a corresponding diet for 35 days and slaughtered. Gut microbiome and SCFA concentration were profiled along the gastrointestinal tract. Results Dietary fiber deprivation-induced consistent microbiota extinction, mainly Bifidobacterium and Lactobacillus, and decreased SCFA concentrations in both ileum and feces. The community structure partially recovered at day 35 compared with baseline while SCFA concentrations remained low. Xylan supplementation alleviated gut dysbiosis by selectively promoting Bifidobacterium pseudocatenulatum within the large intestine. SCFA concentration increased significantly after xylan supplementation and exhibited a positive association with B. pseudocatenulatum abundance. An elevated abundance of xylan degradation-related enzyme genes was also observed in the gut microbiome after xylan supplementation. In vitro growth assay further verified the xylan utilization capacity of B. pseudocatenulatum. Conclusions Dietary fiber deprivation could induce probiotic extinction and loss of the SCFA production while potential pathogen was promoted. Xylan intervention could partially restore dietary fiber deprivation-induced gut dysbiosis through selectively promoting B. pseudocatenulatum and therefore normalizing the gut environment. These findings collectively provide evidence that dietary fiber-driven microbiota metabolism bridges the interplay between microbiome and gut health.

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity worldwide. Tremendous progress has been made in the prevention and treatment of CVD; however, there are still lots of limitations and new technology is needed. Nanoparticles have been studied recently for CVD due to their nanoscale size and unique properties, and hold a potential to be a novel therapy for the treatment. To test the safety and effectiveness of drug-loaded nanoparticles for CVD prior to human studies, animal disease models are unavoidably needed. This review summarized the animal models used in the research of nanoparticles for CVD and provided a generic picture of current use of CVD animal models according to the different types of diseases which should be prioritized when considering the application of nanoparticles in treating CVD. This review would be useful resources not only for life science researchers and clinicians but also for those from chemistry and materials sciences background who may not have a systematic knowledge about CVD animal models.

Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is characterized by chronic and relapsing inflammation within the gastrointestinal tract. Antibiotics have been used to treat IBD, primarily utilizing metronidazole. Although there does seem to be a treatment effect, the broad-spectrum antibiotics that have been used to date are crude tools and have many adverse effects. Available evidence suggests that the host microbiome is implicated in the pathogenesis of IBD, though the key bacteria remain unknown. If the bacterial population can be modified appropriately, the use of antibiotics will have a better therapeutic effect. In this study, mice were fed dextran sodium sulfate (DSS) solution for 5 days, followed by 5 days of normal drinking water, to investigate the gut microbiota response to colitis and the initial alteration of microbiota in recovery phase. Day 0 was considered the normal control, while day 5 and day 10 were considered the colitis mouse model progressive phase and recovery phase, respectively. Results showed that inflammation could induce proportional changes in the gut microbiota. Furthermore, transplanting the microbiota in progressive phase to antibiotic-induced microbiota-depleted mice could induce inflammation similar to colitis, which proves the importance of initial alteration of the microbiota for IBD recovery and the potential of the microbiota as a target for the treatment of IBD. Meanwhile, we have also identified three possible target microorganisms in the development of colitis, namely genera Muribaculaceae (negative correlation), Turicibacter (positive correlation) and Lachnospiraceae (negative correlation) in inflammation status through comprehensive analysis.

Scope. Implantation loss is a considerable cause of early pregnancy loss in humans and mammalian animals. It is not addressed how proliferative uterine defects implicate in implantation loss. Methods and Results. Herein, a comprehensive proteomic analysis was conducted on proliferative endometria from sows with low and normal reproductive performance (LRP and NRP, respectively). Enrichment analysis of differentially expressed proteins revealed alterations in endometrial remodeling, substance metabolism (mainly lipid, nitrogen, and retinol metabolism), immunological modulation, and insulin signaling in LRP sows. Importantly, aberrant lipid metabolite accumulation and dysregulation of insulin signaling were coincidently confirmed in endometria of LPR sows, proving an impaired insulin sensitivity. Furthermore, established high-fat diet- (HFD-) induced insulin-resistant mouse models revealed that uterine insulin resistance beginning before pregnancy deteriorated uterine receptivity and decreased implantation sites and fetal numbers. Mitochondrial biogenesis and fusion were decreased, and reactive oxygen species was overproduced in uteri from the HFD group during the implantation period. Ishikawa and JAR cells directly demonstrated that oxidative stress compromised implantation in vitro. Conclusions. This study demonstrated that uterine insulin sensitivity impairment beginning before pregnancy resulted in implantation and fetal loss associated with oxidative stress induced by mitochondrial dysfunction.

The interactions between cells and nanoparticles has been the focus of recent research in the area. The effects of AgNPs on skin cell lines for further potential biological applications are highlighted. This study aimed to investigate the mechanism of cytotoxic and genotoxic effects of AgNPs nanoparticles on human skin keratinocytes (HaCaT). Genocytotoxic effects of AgNPs was assessed using changes in various cellular parameters of HaCaT cells involving viability, superoxide anion radical production, lactate dehydrogenase release and the levels of the antioxidant enzymes, namely, Catalase, Glutathione peroxidase (GPX) and Superoxide Dismutase (SOD). Superoxide anion was detected using nitroblue tetrazolium NBT reduction assay. LDH levels was evaluated using the standard kit, and activity of antioxidant enzymes such as catalase (CAT), glutathione peroxidase 1 (GPX-1) and superoxide dismutase 1 (SOD-1) were quantified using qPCR. Our results indicated that AgNPs caused severe HaCaT oxidative damage, accompanied by increased the production of superoxide anion levels as well as significant decrease in endogenous antioxidant enzyme of SOD, CAT, GPX expression involved in HaCat cells in vitro. Our study suggests that AgNPs exposure increased oxidative stress levels. Moreover; the low cytotoxic effect observed on human HaCaT keratinocytes suggested that these nano-compounds have a potential toxic effect at the skin level only after long-term exposure.

The limited number of human hematopoietic stem cells (HSCs) has restrained their widespread clinical application. Despite great efforts in recent years, the in vitro expansion of HSCs remains a challenge due to incomplete understanding of the signaling networks underlying HSC self-renewal. Here, we show that culturing human cord blood (CB) CD34+ cells with JNK-IN-8, an inhibitor of the JNK signaling pathway, can enhance the self-renewal of HSCs with a 3.88-fold increase in cell number. These cultured CD34+ cells repopulated recipient mice for 21 weeks and can form secondary engraftment that lasted for more than 21 weeks. Knockdown of c-Jun, a major downstream target in the JNK pathway, promoted the expansion of hematopoietic stem and progenitor cells (HSPCs). Our findings demonstrate a critical role of the JNK pathway in regulating HSC expansion, provide new insights into HSC self-renewal mechanism, and may lead to improved clinical application of HSCs.

Antimicrobial peptide (AMP) can be a promising alternative in various domains. However, further risk information is required. In this study, mice were orally administrated different dosages of recombinant AMP microcin J25 (4.55, 9.1, and 18.2 mg/kg; MccJ25) for 1 week, and the toxicity risk impacts were examined. We evidenced that middle-dosage administration mice had a lower inflammation, better body weight, and ameliorated mucosal morphology, accompanied by reduced intestinal permeability and tighter intestinal barrier. Fecal microbiota composition analysis in middle- or low-dosage mice revealed the Bifidobacterium count was increased and the coliform bacteria count was decreased, and increased in short-chain fatty acid levels. Unexpectedly, there was a risk that high-dosage mice increased intestinal permeability and imbalance of intestinal bacteria. Taken together, these data indicated a safe threshold for usage of MccJ25 in clinical practice. Such studies can effectively enhance the safety of various aspects such as food preservative and drug.

Alterations of Endothelial cells (ECs) play a critical role in different pathogenesis of many serious human diseases, and dysfunction of the vascular endothelium is an indicator for human disorders. Endothelial dysfunction is considered to be an early indicator for atherosclerosis, which is characterised by overexpression of adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Hydrogen peroxide (H2O2) released via neutrophils is an important mediator of endothelial cell function. Ambient production of superoxide anion (O2−) and subsequently H2O2 at low levels is critical for regulating endothelial cell functions and proliferation. In this study, we investigated the effects of H2O2 on the expression of adhesion molecules VCAM-1 and ICAM-1 in cultured human umbilical vein endothelial cells (HUVECs). Intracellular superoxide anion production was detected by using p-Nitro Blue Tetrazolium (NBT) assay. Our results showed that administration of 100μM of H2O2 on HUVECs for 2, 6, 12 and 24 h induced a time-dependent increase in ICAM-1 and VCAM-1 mRNA and protein expression levels with a significant increase observed from 6 h. HUVECs exposed to H2O2 exhibit increased O2−, suggesting that H2O2 induced oxidative stress may be a reasonable for atherosclerosis. This increase can be reduced by the flavonoid, N-acetyl cysteine (NAC). The modulation of endothelial cell function through this mechanism may underlie the contribution of H2O2 to the development of vascular disease.

Glucagon-like peptide-2 (GLP-2) is secreted from enteroendocrine L-type cells of the gut and also released from preproglucagonergic (PPG) neurons in the nucleus tractus solitarius (NTS) and adjacent medial reticular nucleus of the brain stem. The neurons in the NTS express GLP-2, and the neurons send extensive projections to the hypothalamus. Recent studies show that the intracerebroventricular administration of GLP-2 significantly suppresses food intake in animals and some evidence suggest that the melanocortin receptor-4 (MC4-R) signaling in the hypothalamus is required for intracerebroventricular GLP-2-mediated inhibition of feeding. There is proopiomelanocortin (POMC) positive neurons expressing MC4-R in the NTS. Suppression of MC4-R expressing neurons in the brain stem inhibits gastric emptying. In this study, we tested the effects of NTS GLP-2R activation and blockade on feeding behavior and evaluated the endogenous melanocortin system's role in the NTS in mediating effects of GLP-2 on feeding behavior in fed and fasted rats. Our results demonstrated that microinjection of GLP-2 into the NTS suppressed food intake in fasted-refeeding rats but did not affect food intake in free-feeding rats, and this inhibition was blocked by pretreatment of either Exendin (9-39) or SHU 9119, suggesting the GLP-2 system in the NTS exerts an inhibitory action on food intake. MC4-R mediates this action in the NTS.

Treating serious bone trauma with an osteo-inductive agent such as bone morphogenetic proteins (BMPs) has been considered as an optimized option when delivered via a collagen sponge (CS). Previous works have shown that the BMP concentration and release rate from approved CS carriers is difficult to control with precision. Here we presented the fabrication of a recombinant fusion protein from recombinant human-like collagen (HLC) and human BMP-2 (hBMP2). The fusion protein preserved the characteristic of HLC allowing the recombinant protein to be expressed in Yeast (such as Pichia pastoris GS115) and purified rapidly and easily with mass production after methanol induction. It also kept the stable properties of HLC and hBMP2 in the body fluid environment with good biocompatibility and no cytotoxicity. Moreover, the recombinant fusion protein fabricated a vertical through-hole structure with improved mechanical properties, and thus facilitated migration of bone marrow mesenchymal stem cells (MSCs) into the fusion materials. Furthermore, the fusion protein degraded and released hBMP-2 in vivo allowing osteoinductive activity and the enhancement of utilization rate and the precise control of the hBMP2 release. This fusion protein when applied to cranial defects in rats was osteoinductively active and improved bone repairing enhancing the repairing rate 3.5- fold and 4.2- fold when compared to the HLC alone and the control, respectively. There were no visible inflammatory reactions, infections or extrusions around the implantation sites observed. Our data strongly suggests that this novel recombinant fusion protein could be more beneficial in the treatment of bone defects than the simple superposition of the hBMP2/collagen sponge.

Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is rising constantly all over the world. However, current medical treatments are not universally practical. Microcin J25 (MccJ25), a member of the lasso peptides class, has excellent antimicrobial activity both in vitro and in vivo. Here, we assessed the anti-inflammatory effects of MccJ25 through DSS-induced UC mouse model. MccJ25 significantly ameliorated the UC-associated parameters such as decreased body weight, increased disease activity index (DAI) and shortened colon length. MccJ25 also provides barrier protection by preserving structural integrity and reducing inflammatory infiltrates of colon epithelium. The underlying mechanism may be associated with gut microbiota. To test this uncertainty, co-housing experiment was performed, and results indicate homogenized microbiota could relief the inflammatory. Meanwhile, we also proved the prominent role of the possible targets of MccJ25, namely genus Lactobacillus, Bacteroides and Akkermansia (as well as the possible strains related to the important OTUs) in inflammation status through comprehensive analysis. In conclusion, MccJ25 effectively attenuates inflammation and improves disrupted barrier function, and the MccJ25-modified gut microbiota plays a central role in this process.

Background The early-life microbiota exerts a profound and lifelong impact on host health. Longitudinal studies in humans have been informative but are mostly based on the analysis of fecal samples and cannot shed direct light on the early development of mucosa-associated intestinal microbiota and its impact on GI function. Using piglets as a model for human infants, we assess here the succession of mucosa-associated microbiota across the intestinal tract in the first 35 days after birth. Results Although sharing a similar composition and predicted functional profile at birth, the mucosa-associated microbiome in the small intestine (jejunum and ileum) remained relatively stable, while that of the large intestine (cecum and colon) quickly expanded and diversified by day 35. Among detected microbial sources (milk, vagina, areolar skin, and feces of sows, farrowing crate, and incubator), maternal milk microbes were primarily responsible for the colonization of the small intestine, contributing approximately 90% bacteria throughout the first 35 days of the neonatal life. Although maternal milk microbes contributed greater than 90% bacteria to the large intestinal microbiota of neonates upon birth, their presence gradually diminished, and they were replaced by maternal fecal microbes by day 35. We found strong correlations between the relative abundance of specific mucosa-associated microbes, particularly those vertically transmitted from the mother, and the expression levels of multiple intestinal immune and barrier function genes in different segments of the intestinal tract. Conclusion We revealed spatially specific trajectories of microbial colonization of the intestinal mucosa in the small and large intestines, which can be primarily attributed to the colonization by vertically transmitted maternal milk and intestinal microbes. Additionally, these maternal microbes may be involved in the establishment of intestinal immune and barrier functions in neonates. Our findings strengthen the notion that studying fecal samples alone is insufficient to fully understand the co-development of the intestinal microbiota and immune system and suggest the possibility of improving neonatal health through the manipulation of maternal microbiota.

As an important economic insect, Bombyx mori is also a useful model organism for lepidopteran insect. Integrins are evolutionarily conserved from sponges to humans, and play vital roles in many physiological and pathological processes. To explore their diverse functions of integrins in insect, eleven integrins including six α and five β subunits were cloned and characterized from silkworm. Our results showed that integrins from silkworm own more family members compared to other invertebrates. Among those α subunits, integrins α1, α2, and the other four subunits belong to PS1, PS2, and PS3 groups, respectively. The β subunits mainly gather in the insect βν group except the β1 subunit which belongs to the insect β group. Expression profiles demonstrated that the integrins exhibited distinct patterns, but were mainly expressed in hemocytes. α1 and β2 subunits are the predominant ones either in the embryogenesis or larva stages. Interestingly, integrins were significantly up-regulated after stimulated by 20-hydroxyecdysone (20-E) in vivo. These results indicate that integrins perform diverse functions in hemocytes of silkworm. Overall, our results provide a new insight into the functional and evolutionary features of integrins.

Designing the &ldquo, ideal&rdquo, hydrogel/matrix which can load bone morphogenetic protein-2 (BMP-2) in a low dose and with a sustained release is the key for its successful therapeutic application to enhance osteogenesis. The current use of natural collagen sponges as hydrogel/matrix is limited due to the collagen matrix showing weak mechanical strength and unmanageable biodegradability. Furthermore, the efficiency and safe dose usage of the BMP-2 has never been seriously considered other than purely chasing the lowest dose usage and extended-release time. In this paper, we customized a novel enzymatically cross-linked recombinant human-like collagen (HLC) sponge with low immunogenicity, little risk from hidden viruses, and easy production. We obtained a unique vertical pore structure and the porosity of the HLC, which are beneficial for Mesenchymal stem cells (MSCs) migration into the HLC sponge and angiopoiesis. This HLC sponge loading with low dose BMP-2 (1 &micro, g) possessed high mechanical strength along with a burst and a sustained release profile. These merits overcome previous limitations of HLC in bone repair and are safer and more sensitive than commercial collagens. For the first time, we identified that a 5 &micro, g dose of BMP-2 can bring about the side effect of bone overgrowth through this sensitive delivery system. Osteoinduction of the HLC-BMP sponges was proved by an in vivo mouse ectopic bone model and a rat cranial defect repair model. The method and the HLC-BMP sponge have the potential to release other growth factors and aid other tissue regeneration. Additionally, the ability to mass-produce HLC in our study overcomes the current supply shortage, which limits bone repair in the clinic.

The molecular identity of ion channels which confer PCO(2)/pH sensitivity in the brain is unclear. Heteromeric Kir4.1/Kir5.1 channels are highly sensitive to inhibition by intracellular pH and are widely expressed in several brainstem nuclei involved in cardiorespiratory control, including the locus coeruleus. This has therefore led to a proposed role for these channels in neuronal CO(2) chemosensitivity. To examine this, we generated mutant mice lacking the Kir5.1 (Kcnj16) gene. We show that although locus coeruleus neurons from Kcnj16((+/+)) mice rapidly respond to cytoplasmic alkalinization and acidification, those from Kcnj16((-/-)) mice display a dramatically reduced and delayed response. These results identify Kir5.1 as an important determinant of PCO(2)/pH sensitivity in locus coeruleus neurons and suggest that Kir5.1 may be involved in the response to hypercapnic acidosis.

The inwardly-rectifying potassium channel subunit Kir5.1 selectively co-assembles with members of the Kir4.0 subfamily to form novel pH-sensitive heteromeric channels with unique single channel properties. In this study, we have cloned orthologs of Kir4.1 and Kir5.1 from the genome of the amphibian, Xenopus tropicalis (Xt). Heteromeric XtKir4.1/XtKir5.1 channels exhibit similar macroscopic current properties to rat Kir4.1/Kir5.1 with a faster time-dependent rate of activation. However, single channel analysis of heteromeric XtKir4.1/XtKir5.1 channels reveals that they have markedly different long-lived, multi-level subconductance states. Furthermore, we demonstrate that the XtKir5.1 subunit is responsible for these prominent subconductance levels. These results are consistent with a model in which the slow transitions between sublevel states represent the movement of individual subunits. These novel channels now provide an excellent model system to determine the structural basis of subconductance levels and contribution of heteromeric pore architecture to this process.

Recent genetic linkage studies have identified an association between missense variations in the gene encoding the Kir4.1 potassium channel (KCNJ10) and seizure susceptibility phenotypes in both humans and mice. The results of this study demonstrate that these variations (T262S and R271C) do not produce any observable changes in channel function or in predicted channel structure. It is therefore unlikely that the seizure susceptibility phenotypes associated with these missense variations are caused by changes in the intrinsic functional properties of Kir4.1.

An inherited mutation in the KCNK18 gene has been shown to be associated with ‘migraine with aura’. This is a common, debilitating, recurrent headache disorder associated with transient and reversible focal neurological symptoms. KNCK18 encodes the TWIK-related spinal cord potassium channel (TRESK), a member of the K2P family of potassium channels. The F139WfsX24 mutation, segregates perfectly with typical migraine with aura in a large pedigree and functional characterization of this mutation demonstrates that it causes a complete loss of TRESK function and that the mutant subunit suppresses wild-type channel function through a dominant-negative effect, thus explaining the dominant penetrance of this allele (Lafreniere et al, doi:10.1038/nm.2216). This identifies a role for TRESK in the pathogenesis of typical migraine with aura and further supports the role of this channel as a potential therapeutic target. In this study we have examined the electrophysiological properties of other mutations identified in the human KCNK18 gene and find that several of these variants also produce a dramatic dominant-negative phenotype.

Several inwardly-rectifying (Kir) potassium channels (Kir1.1, Kir4.1 and Kir4.2) are characterised by their sensitivity to inhibition by intracellular H(+) within the physiological range. The mechanism by which these channels are regulated by intracellular pH has been the subject of intense scrutiny for over a decade, yet the molecular identity of the titratable pH-sensor remains elusive. In this study we have taken advantage of the acidic intracellular environment of S. cerevisiae and used a K(+) -auxotrophic strain to screen for mutants of Kir1.1 with impaired pH-sensitivity. In addition to the previously identified K80M mutation, this unbiased screening approach identified a novel mutation (S172T) in the second transmembrane domain (TM2) that also produces a marked reduction in pH-sensitivity through destabilization of the closed-state. However, despite this extensive mutagenic approach, no mutations could be identified which removed channel pH-sensitivity or which were likely to act as a separate H(+) -sensor unique to the pH-sensitive Kir channels. In order to explain these results we propose a model in which the pH-sensing mechanism is part of an intrinsic gating mechanism common to all Kir channels, not just the pH-sensitive Kir channels. In this model, mutations which disrupt this pH-sensor would result in an increase, not reduction, in pH-sensitivity. This has major implications for any future studies of Kir channel pH-sensitivity and explains why formal identification of these pH-sensing residues still represents a major challenge.

SummarySpecific stimuli such as intracellular H+ and phosphoinositides (e.g., PIP2) gate inwardly rectifying potassium (Kir) channels by controlling the reversible transition between the closed and open states. This gating mechanism underlies many aspects of Kir channel physiology and pathophysiology; however, its structural basis is not well understood. Here, we demonstrate that H+ and PIP2 use a conserved gating mechanism defined by similar structural changes in the transmembrane (TM) helices and the selectivity filter. Our data support a model in which the gating motion of the TM helices is controlled by an intrasubunit hydrogen bond between TM1 and TM2 at the helix-bundle crossing, and we show that this defines a common gating motif in the Kir channel superfamily. Furthermore, we show that this proposed H-bonding interaction determines Kir channel pH sensitivity, pH and PIP2 gating kinetics, as well as a K+-dependent inactivation process at the selectivity filter and therefore many of the key regulatory mechanisms of Kir channel physiology.

The pH‐sensitive renal potassium channel Kir1.1 is important for K + homeostasis. Disruption of the pH‐sensing mechanism causes type II Bartter syndrome. The pH sensor is thought to be an anomalously titrated lysine residue (K80) that interacts with two arginine residues as part of an ‘RKR triad’. We show that a Kir1.1 orthologue from Fugu rubripes lacks this lysine and yet is still highly pH sensitive, indicating that K80 is not the H + sensor. Instead, K80 functionally interacts with A177 on transmembrane domain 2 at the ‘helix‐bundle crossing’ and controls the ability of pH‐dependent conformational changes to induce pore closure. Although not required for pH inhibition, K80 is indispensable for the coupling of pH gating to the extracellular K + concentration, explaining its conservation in most Kir1.1 orthologues. Furthermore, we demonstrate that instead of interacting with K80, the RKR arginine residues form highly conserved inter‐ and intra‐subunit interactions that are important for Kir channel gating and influence pH sensitivity indirectly.

Purpose: To investigate the effect of aspirin on dexamethasone-induced cataract formation in cultured rat lenses. Methods: One hundred and forty-eight lenses were divided into 3 groups and cultured in vitro: control (DMEM), cataract (DMEM + 10 µM dexamethasone), aspirin (DMEM + 10 µM dexamethasone + 2 mM aspirin). Following incubation, the transparency of the lenses was evaluated daily using a dissecting microscope. Twelve lenses from each group were homogenized and the activities of enzymes (catalase, superoxide dismutase and lactate dehydrogenase) from supernatants were measured after 1, 3, 5 and 7 days of incubation, respectively. The ultrastructure of lenses from the control and cataract groups was observed on the completion of 7-day incubation. Results: Opacity was induced by dexamethasone in the nuclear region of the rat lenses. Lenses in the control group exhibited mist-like opacity and lenses in the cataract group showed dense nuclear opacity, whereas lenses in the aspirin-treated group only had a visible demarcation between nuclear and cortical regions at day 7. The activities of catalase, superoxide dismutase and lactate dehydrogenase in the cataract group decreased in a time-dependent manner. There was no significant loss of enzyme activities in either the control or the aspirin group throughout the incubation period. An orderly arrangement of fiber cells was noted, and the cell membrane, cell junction and organelles were normal in the control group. However, in the cataract group the arrangement of fiber cells was untidy and the lenses contained abnormal-appearing cells. The group exhibited swollen mitochondria, a large number of vacuoles and expanded extracellular lacunae. Conclusions:Dexamethasone induces nuclear cataract in the organ-cultured rat lens by chemically modifying proteins, including enzymes. The enzymes, including those that normally eliminate radial oxygen species, could be especially vulnerable. Aspirin significantly inhibits dexamethasone-induced cataract formation by inhibiting inactivation of those enzymes.

The molecular identity of ion channels which respond to PCO2/pH in the brain is still unclear. Heteromeric Kir4.1/Kir5.1 channels are highly sensitive to inhibition by intracellular pH and are widely expressed in several brainstem nuclei involved in cardiorespiratory control, including the locus coeruleus (LC). This has therefore led to a proposed role for these channels in neuronal CO2-chemosensitivity. In order to examine this we generated mutant mice lacking the Kir5.1 (Kcnj16) gene. We show that whilst LC neurons from Kcnj16(+/+) mice rapidly respond to cytoplasmic alkalinization and acidification, those from Kcnj16(−/−) mice display a dramatically reduced and delayed response. These results identify Kir5.1 as an important determinant of PCO2/pH sensitivity in locus coeruleus neurons and suggest that Kir5.1 is involved in the response to hypercapnic acidosis.