The Mutation P.T613a in the Pore Helix of the Kv 11.1 Potassium Channel is Associated with Long QT Syndrome.

BACKGROUND: Loss-of-function mutations in the voltage gated potassium channel Kv 11.1 have been associated with the Long QT Syndrome (LQTS) type 2. We identified the p.T613A mutation in Kv 11.1 in a family with LQTS. T613A is located in the outer part of the pore helix, a structure that is involved in C-type inactivation. Here we characterize the effect of p.T613A on the functional properties of KV 11.1. METHODS: The p.T613A mutation was introduced into KV 11.1 (T613A). Wild-type KV 11.1 (WT) and T613A were expressed in Xenopus laevis oocytes and characterized by two-electrode-voltage-clamp. RESULTS: T613A currents were reduced to <20% of WT currents and T613A induced a minor negative shift in half maximal rectification, indicating that the voltage-dependent onset on inactivation occurred at more negative voltages compared to WT. Co-expression of T613A with WT revealed intermediate phenotype and there was no dominant negative effect of T613A. CONCLUSION: These findings suggest that p.T613A causes a loss-of-function of Kv 11.1. This results in a reduced repolarizing reserve which may result in LQTS2 and sudden cardiac death.

Calcium-independent phospholipase A2, group VIA, is critical for RPE cell survival.

PURPOSE: To investigate the significance of calcium-independent phospholipase A2, group VIA (iPLA2-VIA), in RPE cell survival following responses to sodium iodate (SI) in cell cultures. METHODS: The human retinal pigment epithelium (RPE) cell line (ARPE-19) cells and primary mouse-RPE cultures were treated with SI to induce cell death. Cells were transfected with an iPLA2-VIA promoter-luciferase construct to evaluate the regulation of iPLA-VIA after exposure to SI. PCR analysis, western blot analysis, and activity assays were performed to evaluate the mRNA level, protein level, and activity levels of iPLA2-VIA after SI exposure. Inhibitors of iPLA2-VIA were used to explore a potential protective role in cells exposed to SI. Primary RPE cell cultures were grown from iPLA2-VIA knockout mice and wild-type mice. The cultures were exposed to SI to investigate a possible increased protection against SI in iPLA2-VIA knockout mice compared to wild-type mice. RESULTS: The study revealed upregulation of iPLA2-VIA expression (promoter activity, iPLA2-VIA mRNA, iPLA2-VIA protein, and iPLA2-VIA protein activity) in ARPE-19 cells exposed to SI. SI-induced cell death was shown to be inhibited by iPLA2-VIA-specific inhibitors in ARPE-19 cell cultures. RPE cultures from iPLA2-VIA knockout mice were less vulnerable to SI-induced cell death compared to RPE cultures from wild-type mice. CONCLUSIONS: SI -induced RPE cell death involves iPLA2-VIA upregulation and activation, and amelioration of SI-induced RPE cell death can be facilitated by inhibitors of iPLA2-VIA. Thus, we suggest iPLA2-VIA as a possible pharmaceutical target to treat RPE-related retinal diseases.

Limited energy supply in Müller cells alters glutamate uptake.

The viability of retinal ganglion cells (RGC) is essential for the maintenance of visual function. RGC homeostasis is maintained by the surrounding retinal glial cells, the Müller cells, which buffer the extracellular concentration of neurotransmitters and provide the RGCs with energy. This study evaluates if glucose-deprivation of Müller cells interferes with their ability to remove glutamate from the extracellular space. The human Müller glial cell line, Moorfields/Institute of Ophthalmology-Müller 1, was used to study changes in glutamate uptake. Excitatory amino acid transporter (EAAT) proteins were up-regulated in glucose-deprived Müller cells and glutamate uptake was significantly increased in the absence of glucose. The present findings revealed an up-regulation of EAAT1 and EAAT2 in glucose-deprived Müller cells as well as an increased ability to take up glutamate. Hence, glucose deprivation may result in an increased ability to protect RGCs from glutamate-induced excitotoxicity, whereas malfunction of glutamate uptake in Müller cells may contribute to retinal neurodegeneration.

Structural modeling and electron paramagnetic resonance spectroscopy of the human Na+/H+ exchanger isoform 1, NHE1.

We previously presented evidence that transmembrane domain (TM) IV and TM X-XI are important for inhibitor binding and ion transport by the human Na(+)/H(+) exchanger, hNHE1 (Pedersen, S. F., King, S. A., Nygaard, E. B., Rigor, R. R., and Cala, P. M. (2007) J. Biol. Chem. 282, 19716-19727). Here, we present a structural model of the transmembrane part of hNHE1 that further supports this conclusion. The hNHE1 model was based on the crystal structure of the Escherichia coli Na(+)/H(+) antiporter, NhaA, and previous cysteine scanning accessibility studies of hNHE1 and was validated by EPR spectroscopy of spin labels in TM IV and TM XI, as well as by functional analysis of hNHE1 mutants. Removal of all endogenous cysteines in hNHE1, introduction of the mutations A173C (TM IV) and/or I461C (TM XI), and expression of the constructs in mammalian cells resulted in functional hNHE1 proteins. The distance between these spin labels was ∼15 A, confirming that TM IV and TM XI are in close proximity. This distance was decreased both at pH 5.1 and in the presence of the NHE1 inhibitor cariporide. A similar TM IV·TM XI distance and a similar change upon a pH shift were found for the cariporide-insensitive Pleuronectes americanus (pa) NHE1; however, in paNHE1, cariporide had no effect on TM IV·TM XI distance. The central role of the TM IV·TM XI arrangement was confirmed by the partial loss of function upon mutation of Arg(425), which the model predicts stabilizes this arrangement. The data are consistent with a role for TM IV and TM XI rearrangements coincident with ion translocation and inhibitor binding by hNHE1.

Perioperative clinical management in relation to emergency surgery for perforated peptic ulcer: A nationwide questionnaire survey.

BACKGROUND & AIMS: Perforation is a severe complication of peptic ulcer disease. Evidence regarding perioperative management of patients undergoing surgery for perforated peptic ulcer is scarce without any clear guidelines. This study aimed to investigate the clinical practice and possible differences in the perioperative management of patients undergoing emergency surgery for perforated peptic ulcers in Denmark. METHODS: The study was an anonymous, nationwide questionnaire survey. All doctors working at general surgical departments in Denmark were included. The questionnaire consisted of four parts; 1) demographic details including job position, subspecialty, geographic location, and surgical experience, 2) pre- and postoperative use of nasoenteral tubes, 3) routine use of nil-by-mouth (NBM) regime, 4) questions regarding postoperative nutrition.Subgroup analyses were performed according to job position and subspecialty. RESULTS: In total, the questionnaire was answered by 287 surgeons, of which 74% were experienced surgeons being able to perform surgery for perforated peptic ulcers independently.Pre- and postoperative nasoenteral tubes were used routinely by the majority of the respondents. One of five surgeons routinely practiced a postoperative NBM regime. Generally, the respondents allowed clear fluids postoperatively without restrictions but were reluctant to allow free fluids or solid foods. Two of three surgeons routinely used tube- or parental nutrition. The results varied depending on job position and subspecialty. CONCLUSIONS: After emergency surgery, the postoperative management of patients with perforated peptic ulcers varies considerably among general surgeons in Denmark. Evidence-based national or international guidelines are needed to standardize and optimize the clinical practice.

Vacuum-assisted closure versus on-demand relaparotomy in patients with secondary peritonitis-the VACOR trial: protocol for a randomised controlled trial.

BACKGROUND: Secondary peritonitis is a severe condition with a 20-32% reported mortality. The accepted treatment modalities are vacuum-assisted closure (VAC) or primary closure with relaparotomy on-demand (ROD). However, no randomised controlled trial has been completed to compare the two methods potential benefits and disadvantages. METHODS: This study will be a randomised controlled multicentre trial, including patients aged 18 years or older with purulent or faecal peritonitis confined to at least two of the four abdominal quadrants originating from the small intestine, colon, or rectum. Randomisation will be web-based to either primary closure with ROD or VAC in blocks of 2, 4, and 6. The primary endpoint is peritonitis-related complications within 30 or 90 days and one year after index operation. Secondary outcomes are comprehensive complication index (CCI) and mortality after 30 or 90 days and one year; quality of life assessment by (SF-36) after three and 12 months, the development of incisional hernia after 12 months assessed by clinical examination and CT-scanning and healthcare resource utilisation. With an estimated superiority of 15% in the primary outcome for VAC, 340 patients must be included. Hospitals in Denmark and Europe will be invited to participate. DISCUSSION: There is no robust evidence for choosing either open abdomen with VAC treatment or primary closure with relaparotomy on-demand in patients with secondary peritonitis. The present study has the potential to answer this important clinical question. TRIAL REGISTRATION: The study protocol has been registered at clinicaltrials.gov (NCT03932461). Protocol version 1.0, 9 January 2022.

Gender-dependent bladder response to one-day bladder outlet obstruction.

BACKGROUND: Development of bladder fibrosis, loss of compliance, and voiding dysfunction are among the severe consequences of various lower urinary conditions, for example, bladder outlet obstruction (BOO), neurogenic bladder, and radiotherapy to the pelvic area. The bladder remodelling results in significant changes in bladder function and architecture, and may ultimately be deleterious for kidney function. The molecular signals underlying pathologic bladder remodelling, as well as the impact of gender, remain poorly understood. OBJECTIVE: To investigate the bladder remodelling after one day BOO, whether the remodelling is different between different bladder sections, and whether genders may affect the remodelling. STUDY DESIGN: Thirty male and 30 female C57BL/6NRj mice were randomly divided into Control, Sham and BOO groups with ten mice per group. A 24-h total urethral obstruction was performed at the proximal urethra. Histological changes were observed via H&E, trichrome and immunohistochemistry staining. Harvested bladders were divided into upper and lower sections for analysis. Protein and gene expression were detected by Western blotting and qPCR. RESULTS: No significant changes in bladder wall thickness were observed following BOO, while increased bladder mass after BOO was found in female mice only. We detected FN and ⍺-SMA upregulation in the male upper bladder segment. Female BOO mice bladders showed increased α-SMA expression in both bladder segments, but no difference of FN was observed in either bladder segments. BOO-induced upregulation of TGF-ß and Gremlin were detected in both male and female bladders, while downregulation of BMP-7 was detected only in male bladders. Furthermore, phosphorylation of both SMAD2/3 and SMAD1/5/9 were increased in male bladders following BOO, whereas female mice exhibited increased pSMAD2/3 in the upper and increased pSMAD1/5/9 in the lower bladder segment. CONCLUSIONS: Our data indicate that some specific proteins and growth factors were detected as early alterations of tissue which may lead to fibrosis. In addition, the males tended to have more pronounced response than females. However, the causes and consequences of the findings need to be further investigated.

Associations Between Online Pornography Consumption and Sexual Dysfunction in Young Men: Multivariate Analysis Based on an International Web-Based Survey.

BACKGROUND: Expanding access to the internet has resulted in more and earlier consumption of online pornography. At the same time, a higher prevalence of erectile dysfunction (ED) among young men is seen. Increased pornography consumption has been suggested as a possible explanation for this rise. OBJECTIVE: The aim of this study was to better understand associations between problematic pornography consumption (PPC) and ED. METHODS: A 118-item survey was published online, and data collection took place between April 2019 and May 2020. Of the 5770 men who responded, the responses from 3419 men between 18 years old and 35 years old were analyzed. The survey used validated questionnaires such as the Cyber Pornography Addiction Test (CYPAT), International Index of Erectile Function (IIEF-5), and Alcohol Use Disorders Identification Test-Concise (AUDIT-C). The estimated amount of porn watching was calculated. Univariable and multivariable analyses were performed. For the multivariable analysis, a logistic regression model using a directed acyclic graph was used. RESULTS: According to their IIEF-5 scores, 21.48% (444/2067) of our sexually active participants (ie, those who attempted penetrative sex in the previous 4 weeks) had some degree of ED. Higher CYPAT scores indicating problematic online pornography consumption resulted in a higher probability of ED, while controlling for covariates. Masturbation frequency seemed not to be a significant factor when assessing ED. CONCLUSIONS: This prevalence of ED in young men is alarmingly high, and the results of this study suggest a significant association with PPC. TRIAL REGISTRATION: Research Registry researchregistry5111; https://tinyurl.com/m45mcaa2.

Pinpointing differences in cisplatin-induced apoptosis in adherent and non-adherent cancer cells.

Platinum compounds are used in the treatment of cancer. We demonstrate that cisplatin-induced (10 µM) apoptosis (caspase-3 activity) is pronounced within 18 hours in non-adherent Ehrlich ascites tumour cells (EATC), whereas there is no increase in caspase-3 activity in the adherent Ehrlich Lettré ascites tumour cells (ELA). Loss of KCl and cell shrinkage are hallmarks in apoptosis and has been shown in EATC. However, we find no reduction in cell volume and only a minor loss of K(+) which is accompanied by net uptake of Na(+) following 18 hours cisplatin exposure in ELA. Glutathione and taurine have previously been demonstrated to protect cells from apoptosis. We find, however, that increase or decrease in the cellular content of glutathione and taurine has no effect on cisplatin-induced cell death in EATC and ELA. Nevertheless, knock-down of the taurine transporter TauT leads to a significant increase in apoptosis in ELA following cisplatin exposure. We find that cytosolic accumulation of cisplatin is similar in EATC and ELA. However, the nuclear accumulation and DNA-binding of cisplatin is significant lower in ELA compared to EATC. We suggest three putative reasons for the observed cisplatin insensitivity in the adherent tumor cells (ELA) compared to the non-adherent tumor cells (EATC): less nuclear cisplatin accumulation, increased TauT activity, and decreased anion and water loss.

Phenylalanine stable isotope tracer labeling of cow milk and meat and human experimental applications to study dietary protein-derived amino acid availability.

BACKGROUND & AIMS: Availability of dietary protein-derived amino acids (AA) is an important determinant for their utilization in metabolism and for protein synthesis. Intrinsic labeling of protein is the only method to directly trace availability and utilization. The purpose of the present study was to produce labeled milk and meat proteins and investigate how dietary protein-derived AA availability is affected by the protein-meal matrix. METHODS: Four lactating cows were infused with L-[ring-d5]phenylalanine and one with L-[15N]phenylalanine for 72 h. Milk was collected, and three of the [d5]phenylalanine cows were subsequently slaughtered. Two human studies were performed to explore plasma AA availability properties utilizing the labeled proteins. One study compared the intake of whey protein either alone or together with carbohydrates-fat food-matrix. The other study compared the intake of meat hydrolysate with minced beef. Cow blood, milk, meat and human blood samples were collected and analyzed by mass spectrometry. RESULTS: Whey and caseinate acquired label to 15-20 mol percent excess (MPE), and the meat proteins reached 0.41-0.73 MPE. The [d5]phenylalanine appeared fast in plasma and peaked 30 min after whey protein alone and meat hydrolysate intake, whereas whey protein with a food-matrix and the meat minced beef postponed the [d5]phenylalanine peak until 2 and 1 h, respectively. CONCLUSIONS: Phenylalanine stable isotope-labeled milk and meat were produced and proved a valuable tool to investigate AA absorption characteristics. Dietary protein in food-matrices showed delayed postprandial plasma AA availability as compared to whey protein alone and meat hydrolysate.

Identification of intracellular phospholipases A2 in the human eye: involvement in phagocytosis of photoreceptor outer segments.

PURPOSE: To identify intracellular phospholipases A(2) (PLA(2)) in the human retina and to explore the role of these enzymes in human retinal pigment epithelium (RPE) phagocytosis of photoreceptor outer segments (POS). METHODS: PCR amplification and Western blot analysis were used to identify mRNA and protein expression of intracellular PLA(2) subtypes in the retinal pigment epithelial cell line ARPE-19. Immunohistochemical staining of normal human eye sections was performed to reveal the cellular location of the enzymes. A model of RPE phagocytosis of POS was used to explore the role of intracellular PLA(2) in phagocytosis. An activity assay was used to evaluate PLA(2) activity, and inhibitors of specific PLA(2) were applied to evaluate the role of PLA(2) in RPE phagocytosis. RESULTS: Genes encoding calcium-independent (i)PLA(2), group VIA; calcium-dependent cytosolic (c)PLA(2), groups IVA, IVB, and IVC; and iPLA(2), group VIB, were identified in the human RPE cell line ARPE-19. Furthermore, protein of iPLA(2)-VIA, cPLA(2)-IVA, and iPLA(2)-VIB were identified in ARPE-19 cells and in various parts of the normal human eye. iPLA(2)-VIA protein levels were upregulated during phagocytosis, and iPLA(2)-VIA activity was found to be specifically increased 12 hours after ARPE-19 cells were fed with POS. Finally, RPE phagocytosis was inhibited by the iPLA(2)-VIA inhibitor bromoenol lactone. CONCLUSIONS: Various intracellular PLA(2) subtypes are present in the human retina. iPLA(2)-VIA may play an important role in the regulation of RPE phagocytosis of POS and may also be involved in the regulation of photoreceptor cell renewal.

Role of phospholipase A2 in the induction of drip loss in porcine muscle.

The role of phospholipase A2 in the induction of drip loss from pig muscle has been investigated. In samples from porcine M. longissimus dorsi, total PLA2 activity as well as mRNA and protein levels of the group VIA iPLA2 (iPLA2-VIA) increased during the initial 4 h post-mortem period. Morphological studies of porcine muscle showed that at 4 h post-mortem, gaps had formed between muscle fibers and that the sarcolemma membrane borders appeared blurred. At the same time iPLA2-VIA protein levels were increased inside muscle fibers and at the sarcolemma. iPLA2-VIA mRNA abundance in samples from different breeds of pigs with variations in drip loss revealed no clear correlation between drip loss level and iPLA2-VIA expression. Together, these data indicate that during the post-mortem period, iPLA2-VIA expression and activity is increased at the muscle fiber membranes. PLA2 activity may affect membrane permeability and consequently the progression of drip formation in porcine muscle.

Molecular Cloning and Functional Expression of the Equine K+ Channel KV11.1 (Ether à Go-Go-Related/KCNH2 Gene) and the Regulatory Subunit KCNE2 from Equine Myocardium.

The KCNH2 and KCNE2 genes encode the cardiac voltage-gated K+ channel KV11.1 and its auxiliary ß subunit KCNE2. KV11.1 is critical for repolarization of the cardiac action potential. In humans, mutations or drug therapy affecting the KV11.1 channel are associated with prolongation of the QT intervals on the ECG and increased risk of ventricular tachyarrhythmia and sudden cardiac death--conditions known as congenital or acquired Long QT syndrome (LQTS), respectively. In horses, sudden, unexplained deaths are a well-known problem. We sequenced the cDNA of the KCNH2 and KCNE2 genes using RACE and conventional PCR on mRNA purified from equine myocardial tissue. Equine KV11.1 and KCNE2 cDNA had a high homology to human genes (93 and 88%, respectively). Equine and human KV11.1 and KV11.1/KCNE2 were expressed in Xenopus laevis oocytes and investigated by two-electrode voltage-clamp. Equine KV11.1 currents were larger compared to human KV11.1, and the voltage dependence of activation was shifted to more negative values with V1/2 = -14.2±1.1 mV and -17.3±0.7, respectively. The onset of inactivation was slower for equine KV11.1 compared to the human homolog. These differences in kinetics may account for the larger amplitude of the equine current. Furthermore, the equine KV11.1 channel was susceptible to pharmacological block with terfenadine. The physiological importance of KV11.1 was investigated in equine right ventricular wedge preparations. Terfenadine prolonged action potential duration and the effect was most pronounced at slow pacing. In conclusion, these findings indicate that horses could be disposed to both congenital and acquired LQTS.

TMEM16F (Anoctamin 6), an anion channel of delayed Ca(2+) activation.

Members of the TMEM16 (Anoctamin) family of membrane proteins have been shown to be essential constituents of the Ca(2+)-activated Cl(-) channel (CaCC) in many cell types. In this study, we have investigated the electrophysiological properties of mouse TMEM16F. Heterologous expression of TMEM16F in HEK293 cells resulted in plasma membrane localization and an outwardly rectifying ICl,Ca that was activated with a delay of several minutes. Furthermore, a significant Na(+) current was activated, and the two permeabilities were correlated according to PNa = 0.3 PCl. The current showed an EC50 of 100 µM intracellular free Ca(2+) concentration and an Eisenman type 1 anion selectivity sequence of PSCN > PI > PBr > PCl > PAsp. The mTMEM16F-associated ICl,Ca was abolished in one mutant of the putative pore region (R592E) but retained in two other mutants (K616E and R636E). The mutant K616E had a lower relative permeability to iodide, and the mutant R636E had an altered anion selectivity sequence (PSCN = PI = PBr = PCl > PAsp). Our data provide evidence that TMEM16F constitutes a Ca(2+)-activated anion channel or a pore-forming subunit of an anion channel with properties distinct from TMEM16A.

Interaction between VEGF and calcium-independent phospholipase A2 in proliferation and migration of retinal pigment epithelium.

PURPOSE: Inhibition of VEGF in the eye is an important treatment modality for reducing proliferation and migration of retinal pigment epithelium (RPE) in age-related macular degeneration (AMD). Additionally, previous studies suggest calcium-independent phospholipase A(2) group VIA (iPLA(2)-VIA) to be a potential regulator of cell proliferation and migration, and evidence show abundant expression of iPLA(2)-VIA in RPE cells. The aim of the present study was to evaluate the potential role of iPLA(2)-VIA in VEGF-induced proliferation and migration of RPE cells. MATERIALS AND METHODS: The human RPE cell line, ARPE-19, was used in all assays. To explore the role of iPLA(2)-VIA in VEGF-induced RPE proliferation and migration, iPLA(2)-VIA inhibition by the iPLA(2)-VIA specific inhibitor, bromoenol lactone, was done. RPE cell proliferation and migration were evaluated by measurements of incorporated radioactive thymidine in DNA and by a Boyden chamber technique, respectively. A luciferase assay monitored the VEGF-induced iPLA(2)-VIA transcriptional activity. Western blot analysis and an activity assay were used to detect the protein levels and activity of iPLA(2)-VIA respectively after treatment with VEGF. RESULTS: RPE cells treated with VEGF showed significant increased proliferation and migration. Furthermore, inhibition of iPLA(2)-VIA significantly reduced the spontaneous proliferation and migration as well as the VEGF-induced proliferation and migration. Finally, inhibition of iPLA(2)-VIA reduced the VEGF-induced iPLA(2)-VIA-activity, -protein level, and -promoter activity. CONCLUSIONS: A significant interaction between VEGF and iPLA(2)-VIA in the regulation of RPE cells appears to be relevant in elucidating the exact mechanisms of action in the proliferative and migratory phenotype of RPE cells in AMD.

The stress response protein Gls24 is induced by copper and interacts with the CopZ copper chaperone of Enterococcus hirae.

Intracellular copper routing in Enterococcus hirae is accomplished by the CopZ copper chaperone. Under copper stress, CopZ donates Cu(+) to the CopY repressor, thereby releasing its bound zinc and abolishing repressor-DNA interaction. This in turn induces the expression of the cop operon, which encodes CopY and CopZ, in addition to two copper ATPases, CopA and CopB. To gain further insight into the function of CopZ, the yeast two-hybrid system was used to screen for proteins interacting with the copper chaperone. This led to the identification of Gls24, a member of a family of stress response proteins. Gls24 is part of an operon containing eight genes. The operon was induced by a range of stress conditions, but most notably by copper. Gls24 was overexpressed and purified, and was shown by surface plasmon resonance analysis to also interact with CopZ in vitro. Circular dichroism measurements revealed that Gls24 is partially unstructured. The current findings establish a novel link between Gls24 and copper homeostasis.

HL-1 mouse cardiomyocyte injury and death after simulated ischemia and reperfusion: roles of pH, Ca2+-independent phospholipase A2, and Na+/H+ exchange.

The Ca(2+)-independent phospholipase A(2) VI (iPLA(2)-VI) and the Na(+)/H(+) exchanger isoform 1 (NHE1) are highly pH-sensitive proteins that exert both protective and detrimental effects in cardiac ischemia-reperfusion. Here, we investigated the role of extracellular pH (pH(o)) in ischemia-reperfusion injury and death and in regulation and function of iPLA(2)-VI and NHE1 under these conditions. HL-1 cardiomyocytes were exposed to simulated ischemia (SI; 0.5% O(2), 8 mM K(+), and 20 mM lactate) at pH(o) 6.0 and 7.4, with or without 4 or 8 h of reperfusion (SI/R). Cytochrome c release and caspase-3 activation were reduced after acidic compared with neutral SI, whereas necrotic death, estimated as glucose-6-phosphate dehydrogenase release, was similar in the two conditions. Inhibition of iPLA(2)-VI activity by bromoenol lactone (BEL) elicited cardiomyocyte necrosis during normoxia and after acidic, yet not after neutral, SI. The isoform-selective enantiomers R- and S-BEL both mimicked the effect of racemic BEL after acidic SI. In contrast, inhibition of NHE activity by EIPA had no significant effect on necrosis after SI. Both neutral and acidic SI were associated with a reversible loss of F-actin and cortactin integrity. Inhibition of iPLA(2)-VI disrupted F-actin, cortactin, and mitochondrial integrity, whereas inhibition of NHE slightly reduced stress fiber content. iPLA(2)-VIA and NHE1 mRNA levels were reduced during SI and upregulated in a pH(o)-dependent manner during SI/R. This also affected the subcellular localization of iPLA(2)-VIA. Thus, the mode of cell death and the roles and regulation of iPLA(2)-VI and NHE1 are at least in part determined by the pH(o) during SI. In addition to having clinically relevant implications, these findings can in part explain the contradictory results obtained from previous studies of iPLA(2)-VIA and NHE1 during cardiac I/R.

Cyclooxygenase-2 immunoreactivity in collagenous colitis.

Collagenous colitis (CC) is an inflammatory bowel disease of unknown aetiology and pathogenesis. In ulcerative colitis and Crohn's disease, prostaglandins may be involved in the pathogenesis of inflammation, and increased expression of cyclo-oxygenase-2 (COX-2) has been detected. The purpose of this study was to examine the presence and cellular localization of COX-2 in colonic mucosa of patients with CC. Using immunohistochemistry, immunoflouresence and Western blot analysis, COX-2 expression was evaluated in colonic mucosal biopsies from 10 patients with active untreated CC, and compared with samples from eight normal controls, and samples from eight patients with ulcerative colitis or Crohn's disease. Specimens from patients with CC expressed COX-2 protein in increased amounts compared with controls, but similar to patients with ulcerative colitis and Crohn's disease. COX-2 expression was localized to the mononuclear cells of the lamina propria. COX-2 expression was most evident in macrophages. Co-localization of COX-2 and macrophages was increased in number in comparison with controls. In conclusion COX-2 is expressed in increased amounts primarily in the macrophage subpopulation of the inflammatory infiltrate of lamina propria in CC. Increased recruitment of macrophages, increased expression of COX-2 and increased prostaglandin synthesis may be involved in the pathogenesis of CC.

Lab-on-a-chip technology for continuous glucose monitoring.

The demand for continuous glucose monitoring systems is greater than ever. The microelectromechanical systems (MEMS) approach has the advantage of being relatively easy to upscale to a commercial level; the preferred MEMS technique would be to run several detectors at once and, through the improved statistics, get a both more accurate and more reliable device than is currently available. Lab-on-a-chip technology may be seen as a further development of MEMS technology for analytical sensors. Lab-on-a-chip systems may be used to obtain improvements on several important characteristics of a sensor system: remove or decrease cross-sensitivity, improve sensor stability, improve accuracy, and/or improve response time compared to similar laboratory-equipment methods.

Roles of phospholipase A2 isoforms in swelling- and melittin-induced arachidonic acid release and taurine efflux in NIH3T3 fibroblasts.

Osmotic swelling of NIH3T3 mouse fibroblasts activates a bromoenol lactone (BEL)-sensitive taurine efflux, pointing to the involvement of a Ca(2+)-independent phospholipase A(2) (iPLA(2)) (Lambert IH. J Membr Biol 192: 19-32, 2003). We report that taurine efflux from NIH3T3 cells was not only increased by cell swelling but also decreased by cell shrinkage. Arachidonic acid release to the cell exterior was similarly decreased by shrinkage yet not detectably increased by swelling. NIH3T3 cells were found to express cytosolic calcium-dependent cPLA(2)-IVA, cPLA(2)-IVB, cPLA(2)-IVC, iPLA(2)-VIA, iPLA(2)-VIB, and secretory sPLA(2)-V. Arachidonic acid release from swollen cells was partially inhibited by BEL and by the sPLA(2)-inhibitor manoalide. Cell swelling elicited BEL-sensitive arachidonic acid release from the nucleus, to which iPLA(2)-VIA localized. Exposure to the bee venom peptide melittin, to increase PLA(2) substrate availability, potentiated arachidonic acid release and osmolyte efflux in a volume-sensitive, 5-lipoxygenase-dependent, cyclooxygenase-independent manner. Melittin-induced arachidonic acid release was inhibited by manoalide and slightly but significantly by BEL. A BEL-sensitive, melittin-induced PLA(2) activity was also detected in lysates devoid of sPLA(2), indicating that both sPLA(2) and iPLA(2) contribute to arachidonic acid release in vivo. Swelling-induced taurine efflux was inhibited potently by BEL and partially by manoalide, whereas the reverse was true for melittin-induced taurine efflux. It is suggested that in NIH3T3 cells, swelling-induced taurine efflux is dependent at least in part on arachidonic acid release by iPLA(2) and possibly also by sPLA(2), whereas melittin-induced taurine efflux is dependent on arachidonic acid release by sPLA(2) and, to a lesser extent, iPLA(2).