Artificial oocyte activation to improve reproductive outcomes in couples with various causes of infertility: a retrospective cohort study.

RESEARCH QUESTION: Does calcium ionophore treatment of oocytes improve fertilization rate, embryo development and outcomes in specific groups of infertile couples? DESIGN: This retrospective cohort study involved 796 couples undergoing oocyte activation with calcium ionophore (A23187) after intracytoplasmic sperm injection (ICSI) between 2016 and 2018. All metaphase II oocytes were exposed to 5 µmol/l ionophore for 15 min immediately after ICSI, cultured in vitro to the blastocyst stage, and transferred to the uteri of recipients on day 5 or cryopreserved for transfer in the next cycle. The previous cycles of the same patients formed the control group. RESULTS: Among 1261 ICSI cycles and 796 ICSI-artificial oocyte activation (ICSI-AOA) cycles, implantation, positive beta-HCG, clinical pregnancy and live birth rates were significantly (P < 0.05 to P < 0.001) improved for all groups, compared with previous cycles, except live birth rate in women with primary ovarian insufficiency (POI). Compared with previous cycles, rates of blastulation (all P < 0.001) and high-quality blastocysts (P < 0.05 to P < 0.001) were increased significantly for couples with male factor (oligoasthenoteratozoospermia [OAT]), unexplained infertility and couples with both factors in the ICSI-AOA cycles. High-quality blastocyst rate was increased in couples with polycystic ovary syndrome (PCOS) (P = 0.0453). Miscarriage rates were decreased significantly (P < 0.05 to P < 0.001) in couples with OAT, PCOS and unexplained infertility in the treatment cycles. No significant differences were found for fertilization rate, embryo development or live birth rate in patients with POI between both groups. CONCLUSIONS: Artificial oocyte activation was able to 'rescue' the poor reproductive outcomes in certain types of infertile couples with history of failure to achieve pregnancy.

Xanthone suppresses allergic contact dermatitis in vitro and in vivo.

Xanthone is a phenolic compound found in a few higher plant families; it has a variety of biological activities, including antioxidant, anti-inflammatory, and anticancer properties. However, the molecular and cellular mechanisms underlying the activity of xanthone in allergic contact dermatitis (ACD) remain to be explored. Therefore, this study aimed to investigate the regulatory effects of xanthone in ACD in human keratinocytes (HaCaT cell), and human mast cell line (HMC-1 cell) in vitro and in an experimental murine model. The results demonstrated that treatment with xanthone reduced the production of pro-inflammatory cytokines and chemokines including interleukin (IL)-1ß, IL-6, IL-8, and expression of chemokines thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in tumor necrosis factor (TNF)-α and interferon (IFN)-γ-stimulated HaCaT cells. Xanthone also suppressed the production of pro-inflammatory cytokines, chemokines, and allergic mediators in phorbol myristate acetate/A23187 calcium ionophore (PMACI)-stimulated HMC-1 cells. Xanthone significantly suppressed the phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) and activation of caspase-1 signaling pathway in vitro model. Additionally, xanthone administration alleviated 2,4-dinitrofluorobenzene (DNFB)-induced atopic dermatitis like-skin lesion by reducing the serum levels of immunoglobulin E (IgE), histamine, and pro-inflammatory cytokines and suppressing MAPKs phosphorylation. Xanthone administration also inhibited mortality due to compound 48/80-induced anaphylactic shock and suppressed the passive cutaneous anaphylaxis (PCA) reaction mediated by IgE. Collectively, these results suggest that xanthone has a potential for use in the treatment of allergic inflammatory diseases.

The combination of calcium ionophore A23187 and GM-CSF can safely salvage aged human unfertilized oocytes after ICSI.

PURPOSE: Artificial oocyte activation using calcium ionophores and enhancement of embryonic developmental potential by the granulocyte-macrophage colony-stimulating factor (GM-CSF) have already been reported. In this study, we evaluated the synergistic effect of these two methods on aged human unfertilized oocytes after intracytoplasmic sperm injection (ICSI). Then, we cultured the resulting embryos to the blastocyst stage and screened them for chromosomal abnormalities, to assess the safety of this protocol. METHODS: Aged human oocytes deemed unfertilized after ICSI were activated, either by briefly applying the calcium ionophore A23187 alone (group A) or by briefly applying the ionophore and then supplementing the culture medium with recombinant human GM-CSF (rhGM-CSF) (group B). Next, the development was monitored in a time-lapse incubator system, and ploidy was analyzed by array comparative genomic hybridization (aCGH), after whole embryo biopsy and whole genome amplification. Differences between oocytes and resulting embryos in both groups were evaluated statistically. RESULTS: Oocytes unfertilized after ICSI can be activated with the calcium ionophore A23187 to show two pronuclei and two polar bodies. Addition of rhGM-CSF in the culture medium of A23187-activated oocytes enhances their cleaving and blastulation potential and results in more euploid blastocysts compared to the culture medium alone. CONCLUSIONS: This study shows that activating post-ICSI aged human unfertilized oocytes with a combination of a calcium ionophore and a cytokine can produce good-morphology euploid blastocysts.

Synergism between phorbol myristate acetate and calcium ionophore in inducing proliferation of in vitro γ-irradiated murine lymphocytes.

The objective of this study was to analyze the in vitro effects of γ-irradiation (0-5 Gy) on lymphocyte proliferation in animals sensitive to radiation as BALB/c mice. Lymphocytes were irradiated and underwent different treatments: quiescent cells were cultured with calcium ionophore A23187 (5 min or 48 h) with or without phorbol myristate acetate (PMA); lymphocytes (control cells or incubated with A23187 and PMA) were also cultured with four mitogens that are specific to the different subpopulations to determine the degree of inhibition of the response to radiation. Results obtained indicated that in quiescent cells, A23187 and PMA treatment had a mitogenic effect, which peaked with long A23187 treatment (48 h); synergism was further demonstrated between both drugs and was enhanced with higher ionizing radiation doses. However, in both irradiated and non-irradiated mitogen-stimulated cells, A23187 (48 h) and PMA had a strong inhibitory effect on cell proliferation. In conclusion these results indicate that irradiated BALB/c mice lymphocytes respond to treatment with A23187 and PMA more actively than controls. Inhibition of the post-exposure mitogen-induced proliferative response and the synergic effect between A23187 and PMA also suggest altered PKC activation mechanisms in cell membranes. Comparing with previous studies with in vivo irradiated mice, the effects of IR in vitro were less intense.

Lysophospholipid acyltransferases and eicosanoid biosynthesis in zebrafish myeloid cells.

Eicosanoids derived from the enzymatic oxidation of arachidonic acid play important roles in a large number of physiological and pathological processes in humans. Many animal and cellular models have been used to investigate the intricate mechanisms regulating their biosynthesis and actions. Zebrafish is a widely used model to study the embryonic development of vertebrates. It expresses homologs of the key enzymes involved in eicosanoid production, and eicosanoids have been detected in extracts from adult or embryonic fish. In this study we prepared cell suspensions from kidney marrow, the main hematopoietic organ in fish. Upon stimulation with calcium ionophore, these cells produced eicosanoids including PGE2, LTB4, 5-HETE and, most abundantly, 12-HETE. They also produced small amounts of LTB5 derived from eicosapentaenoic acid. These eicosanoids were also produced in kidney marrow cells stimulated with ATP, and this production was greatly enhanced by preincubation with thimerosal, an inhibitor of arachidonate reacylation into phospholipids. Microsomes from these cells exhibited acyltransferase activities consistent with expression of MBOAT5/LPCAT3 and MBOAT7/LPIAT1, the main arachidonoyl-CoA:lysophospholipid acyltransferases. In summary, this work introduces a new cellular model to study the regulation of eicosanoid production through a phospholipid deacylation-reacylation cycle from a well-established, versatile vertebrate model species.

The analysis of chemotherapy resistance in human lung cancer cell line with microchip-based system.

Microchip-based systems have many desirable characteristics and can be used in much cellular biochemical analysis. Glucose-regulated protein 78 (GRP78), an endoplasmic reticulum chaperone, has a critical role in chemotherapy resistance of some cancers. This work aimed at analyzing the correlation between the expression of GRP78 and an anticancer drug, topoisomerase II inhibitor-VP-16, in human lung cancer cell line NCI-H460 using this microchip-based system. The cells were cultured on a PDMS chip, the expression of GRP78 at both protein and mRNA levels for the cells under the condition with or without the induction of A23187 were assayed by immunofluorescence and chip electrophoresis, respectively. Then the cells were treated by VP-16, percentages of apoptosis and the cycle distributions of the cells were detected by flow cytometry. The cells cultured on the PDMS attached and spread well to micro-channels with high viability. Compared with the non-induced cells, the expression of GRP78 at both protein and mRNA levels for the A23187-induced cells were increased greatly. After treatment by VP-16, the percentage of apoptotic cells decreased nearly threefold for the A23187-induced cells in contrast to the non-induced cells (13.15 +/- 3.84% versus 34.03 +/- 11.45%), and the cells distributed in S phase reduced dramatically (11.96 +/- 1.27% versus 20.76 +/- 3.05%) whereas in G(1) phase increased greatly (74.16 +/- 0.95% versus 57.06 +/- 4%). GRP78 is correlated to the resistance to VP-16 in human lung cancer cell line. The microchip-based system has the potential application and feasibility for cell culture and its functional research.

A novel liposomal irinotecan formulation with significant anti-tumour activity: use of the divalent cation ionophore A23187 and copper-containing liposomes to improve drug retention.

We determined whether the method used to encapsulate irinotecan into 1,2-distearoyl-sn-glycero-phosphocholine/cholesterol (DSPC/Chol; 55:45 mol%) liposomes influenced: (i) irinotecan release rate and (ii) therapeutic efficacy. DSPC/Chol (55:45 mol%) liposomes were prepared with: (i) unbuffered CuSO4; (ii) buffered (pH 7.5) CuSO4; (iii) unbuffered MnSO4 and the ionophore A23187 (exchanges internal metal2+ with external 2H+ to establish and maintain a transmembrane pH gradient); and (iv) unbuffered CuSO4 and ionophore A23187. All formulations exhibited >98% irinotecan encapsulation (0.2 drug-to-lipid molar ratio; 10 min incubation at 50 degrees C). Following a single intravenous injection (100mg/kg irinotecan) into Balb/c mice, the unbuffered CuSO4 plus A23187 formulation mediated a half-life of irinotecan release of 44.4h; a >or=4-fold increase compared to the other liposome formulations. This surprising observation demonstrated that the CuSO4 plus A23187 formulation enhanced irinotecan retention compared to the MnSO4 plus A23187 formulation, indicating the importance of the divalent metal. A single dose of the CuSO4 plus A23187 formulation (50mg/kg irinotecan) mediated an 18-fold increase in median T-C (the difference in days for treated and control subcutaneous human LS 180 adenocarcinoma xenografts to increase their initial volume by 400%) when compared to a comparable dose of Camptosar. Improved irinotecan retention was associated with increased therapeutic activity.

Increase in intracellular Ca2+ concentration is not the only cause of lidocaine-induced cell damage in the cultured neurons of Lymnaea stagnalis.

PURPOSE: To determine whether the increase in intracellular Ca2+ concentration induced by lidocaine produces neurotoxicity, we compared morphological changes and Ca2+ concentrations, using fura-2 imaging, in the cultured neurons of Lymnaea stagnalis. METHODS: We used BAPTA-AM, a Ca2+ chelator, to prevent the increase in the intracellular Ca2+ concentration, and Calcimycin A23187, a Ca2+ ionophore, to identify the relationship between increased intracellular Ca(2+) concentrations and neuronal damage without lidocaine. Morphological changes were confirmed using trypan blue to stain the cells. RESULTS: Increasing the dose of lidocaine increased the intracellular Ca2+ concentration; however, there was no morphological damage to the cells in lidocaine at 3 x 10(-3) M. Lidocaine at 3 x 10(-2) M increased the intracellular Ca2+ concentration in both saline (from 238 +/- 63 to 1038 +/- 156 nM) and Ca2+-free medium (from 211 +/- 97 to 1046 +/- 169 nM) and produced morphological damage and shrinkage, with the formation of a rugged surface. With the addition of BAPTA-AM, lidocaine at 3 x 10(-2) M moderately increased the intracellular Ca2+ concentration (from 150 +/- 97 to 428 +/- 246 nM) and produced morphological damage. These morphologically changed cells were stained dark blue with trypan blue dye. The Ca2+ ionophore increased the intracellular Ca2+ concentration (from 277 +/- 191 to 1323 +/- 67 nM) and decreased it to 186 +/- 109 nM at 60 min. Morphological damage was not observed during the 60 min, but became apparent a few hours later. CONCLUSION: These results indicated that the increase in intracellular Ca2+ concentration is not the only cause of lidocaine-induced cell damage.

An evaluation of transmembrane ion gradient-mediated encapsulation of topotecan within liposomes.

Topotecan can be encapsulated in liposomes, however little is known about the role encapsulated counter ions play in drug loading efficiency and drug release. Using 1,2-distearoyl-sn-glycero-3 phosphatidylcholine and cholesterol liposomes (55:45 mole ratio), encapsulation was achieved using manganese ion gradients (MnSO(4) or MnCl(2)), with the addition of A23187, a divalent cation/proton exchanger, to maintain a pH gradient. This methodology was compared to procedures where the pH gradient was generated by use of encapsulated (NH(4))(2)SO(4) or citrate (300 mM, pH 3.5). All methods facilitated topotecan encapsulation. Liposomes prepared in the presence of the citrate and MnCl(2) (+A23187) exhibited reduced loading capacities. Liposomes prepared in the presence of (NH(4))(2)SO(4) and MnSO(4) (+A23187) could be used to generate liposomes exhibiting a drug-to-lipid ratio of 0.3 (wt/wt) with an encapsulation efficiency of >90%. In vitro drug release data suggested that the (NH(4))(2)SO(4) and MnSO(4) (+A23187) formulations released drug at a reduced rate. For these formulations, the drug release rates decreased as the drug-to-lipid ratio (wt/wt) increased from 0.1 to 0.2. Cryo-electron micrographs indicated that encapsulated topotecan precipitated as linear particles within liposomes. The stability of topotecan loaded liposomes appeared to be dependent on the presence of both a pH gradient and encapsulated sulfate.

Selectively enhanced sensitivity of bronchoalveolar lavage fluid (BALF) mast cells to IgE dependent stimulation in mild asthmatics.

The aim of this study is to investigate the histamine-releasing ability of mast cells from asthmatic bronchoalveolar lavage fluid (BALF). Following the measurement of the forced expiratory volume at the first second (FEV1), 29 mild asthmatics were included in the study and were subjected to fibreoptic bronchoscopy. The cells recovered from the BALF were challenged with anti-IgE, calcium ionophore A23187 (CI) or adenosine, and the released histamine was measured with an enzyme-linked chromogenic assay. Enzymatically dispersed mast cells from human lung or colon tissues were employed as control groups. The results showed that mast cells from BALF were at least 100 fold more sensitive to anti-IgE than those from lung or colon tissues. However, there was little difference between mast cells from BALF, lung or colon tissues in response to CI. Adenosine failed to stimulate histamine release from BALF mast cells. In conclusion, asthmatic BALF mast cells are much more sensitive to IgE-dependent stimulation than the non-IgE-dependent ones, indicating that mast cells may play a role in the pathogenesis of asthma.

Involvement of cholinoceptors in cadmium-induced endothelial dysfunction.

Cadmium (Cd) toxicity was produced in male rats to study the role of cholinoceptors in Cd-induced endothelial dysfunction. The changes in the tension of the aortic rings to constrictor and dilator agonists were compared with those of controls. A Cd-induced significant increase in phenylephrine response was associated with a decrease in basal dilator prostanoid release. In Cd-exposed rings, despite an obvious depression in the acetylcholine (ACh) response, the receptor-independent dilation to the calcium ionophore A23187, which elicits a receptor-independent endothelial relaxation, was slightly elevated (p<0.01), but the smooth muscle cell response to the NO donor, sodium nitroprusside (SNP) remained unaltered. Cadmium decreased both the maximal response to ACh (10(-5) M) and its pirenzepine (Prz) sensitive component. The M1 type cholinoceptor-mediated response to ACh decreased in Cd-exposed rings to 10.30 +/- 5.00% from 38.40 +/- 6.90% (p<0.001). Cadmium also reduced the share of indomethacin 1.64% to 13.92 +/- 2.89% (p<0.01), which correlated well with the changes in the M1-mediated response (r=0.991, p<0.0001). Most of the deleterious effect of Cd appears to be restricted to the M1-dependent ACh response. These findings suggest that Cd produces an endothelial dysfunction by impairing the M1 type cholinoceptor mediated response, which seems to be involved in prostanoid release.

Studies on glycogen autophagy: effects of phorbol myristate acetate, ionophore A23187, or phentolamine.

The effects of agents that could manipulate the lysosomal calcium such as phorbol myristate acetate, ionophore A23187, and phentolamine on the lysosomal glycogen degradation were studied by electron microscopy, morphometric analysis, and biochemical assays in newborn rat hepatocytes. Phorbol myristate acetate, which promotes the input of calcium to lysosomes, increased the total volume of autophagic vacuoles and the activity of lysosomal glycogen-hydrolyzing acid alpha 1,4 glucosidase and decreased the fractional volume of undigested glycogen inside the autophagic vacuoles and also decreased the activity of acid mannose 6-phosphatase. Ionophore A23187, which releases lysosomal calcium, produced opposite results in these enzyme activities. Phentolamine, an alpha-adrenergic blocking agent which interferes with the generation of phosphoinositides and may activate the lysosomal calcium uptake pump, increased the total volume of autophagic vacuoles and the activity of lysosomal glycogen-hydrolyzing acid glucosidase and decreased the fractional volume of undigested glycogen inside the autophagic vacuoles. The results of this study constitute evidence that changes in lysosomal calcium may influence certain aspects of autophagy, including the degradation of glycogen inside the autophagic vacuoles. They also support our previous postulate [Kalamidas and Kotoulas (2000a,b) Histol Histopathol 15:29-35, 1011-1018] that stimulation of autophagic mechanisms in newborn rat hepatocytes may be associated with acid mannose 6-phosphatase activity-deficient lysosomes.

Activation of cumulus-free equine oocytes: effect of maturation medium, calcium ionophore concentration and duration of cycloheximide exposure.

Two different culture media (TCM-199 and follicular fluid), two activation treatments (10 and 50 micromol calcium ionophore l(-1)) and three culture periods with cycloheximide were evaluated to find effective culture conditions for activation of cumulus-free equine oocytes. Oocytes were collected by scraping the follicle walls of ovaries obtained from an abattoir. Oocytes with expanded cumuli were matured at 38.2 degrees C in a humidified atmosphere of 5% CO(2) in air, in either TCM-199 with 10% fetal bovine serum (FBS) and 5 microU FSH ml(-1), or in 100% follicular fluid derived from a preovulatory follicle 24 h after injection of hCG. After 40--42 h of in vitro maturation, oocytes were denuded by gentle pipetting in TCM-199 plus 10% FBS with hyaluronidase. Oocytes with intact cytoplasmic membranes (n = 398; 94% presumed metaphase II) were treated in protein-free PBS with 10 or 50 micromol calcium ionophore l(-1) for 5 min. After washing, the oocytes were cultured in TCM-199 containing 10% FBS and 10 microg cycloheximide ml(-1) for 6 h, in cycloheximide for 6 h and then in cycloheximide-free medium for 18 h, or in cycloheximide for 24 h. The oocytes were fixed and evaluated by fluorescence microscopy. Oocytes with pronucleus I--II (dense to decondensing chromatin), pronucleus III--IV (decondensed chromatin) or progressing towards the first cleavage division were considered activated. The activation rate for oocytes matured in TCM-199 was significantly (P < 0.05) higher than for oocytes matured in follicular fluid (49% (99/204) versus 35% (60/171), respectively; P < 0.05). Culture with cycloheximide for 24 h resulted in a significantly higher rate of activation (67%, 74/111) than did the 6 h (33%, 44/136) or 6 h plus 18 h (32%, 41/128) treatments. The highest rate of activation (82%) was observed in oocytes matured in TCM-199, treated with 50 micromol calcium ionophore l(-1) and cultured with cycloheximide for 24 h.

Anion efflux from cytotrophoblast cells derived from normal term human placenta is stimulated by hyposmotic challenge and extracellular A23187 but not by membrane-soluble cAMP.

The regulation of placental anion transport influences fetal accretion and placental homeostasis. We investigated whether efflux of 125I- or 36Cl- from multinucleated cytotrophoblast cells derived from human term placenta is regulated by one of three stimuli: (a) the calcium ionophore A23187, (b) a 'cocktail' of agents designed to raise intracellular levels of cAMP, (c) a hyposmotic solution. After loading with the appropriate isotope for 2 h and thorough washing, cells were exposed to sequential aliquots of buffer applied and removed each minute. Following an equilibration period of 5 min one of the stimuli was applied at room temperature At the end of the experiment the cells were lysed to give a lysate count which was used to express the count obtained from each aliquot as percentage efflux of that possible for that minute. The cAMP 'cocktail' and A23187 were applied for 5 min; the hyposmotic solution was applied for 10 min. The results for 125I- at 7 min showed that the mean efflux in the presence of hyposmotic shock was greater than control (5.7 +/- 1.0% min-1 versus 2.2 +/- 0.1% min-1, respectively; mean +/- S.E.M., n = 4 placentas). Similarly mean efflux at 6 min in the presence of A23187 was also significantly greater than control (6.5 +/- 1.9% min-1 versus 2.6 +/- 1.0% min-1, respectively, n = 3 placentas). The mean efflux in the presence of the cAMP cocktail was not different from control at any time point. The results were qualitatively the same if 36Cl- was used in the place of 125I- and when the experiment was performed with 36Cl- in a HCO3- buffer gassed with CO2. Mean 125I- efflux at 6 min in response to hyposmotic challenge was 33% less (P < 0.01) in the presence of 1 mM 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) and 37% less (P < 0.005) in the presence of 10 microM tamoxifen but no different if the hyposmotic solution was nominally calcium free. We conclude that there are differential effects of second messengers on anion efflux from the differentiated cytotrophoblast cells.

In-utero and neonatal exposure to secondhand smoke causes vascular dysfunction in newborn rats.

OBJECTIVES: We sought to determine the effects of secondhand smoke (SHS) exposure on vascular reactivity in newborn and infant rats. BACKGROUND: Secondhand smoke exposure increases cardiovascular risk. Secondhand smoke-induced endothelial dysfunction has been demonstrated in older teenagers and young adults. We have previously shown in adult rabbits that SHS induces atherogenesis and endothelial dysfunction. The effects of SHS on vascular function in the offspring of SHS-exposed mothers and in infants are unknown. METHODS: In this study the effects of in-utero (21 days) and neonatal (28 days) exposure to SHS were examined in 80 rats, 4 weeks of age, in a 2-by-2 design study. Rats were exposed to sidestream smoke in smoking chambers. Aortic rings were excised and isometric force responses to phenylephrine, acetylcholine, A23187 and nitroglycerin were studied in organ baths. RESULTS: Neonatal SHS exposure reduced animal weight (p=0.009). In-utero exposure increased the sensitivity (decreased the EC50) of aortic rings to phenylephrine (p < 0.0005), as did neonatal exposure (p=0.01). Maximal contraction to phenylephrine was reduced by in-utero exposure (p=0.04). In-utero SHS exposure reduced maximal endothelium-dependent relaxation to acetylcholine (p=0.04) and increased the EC50 (p=0.05), suggesting impaired sensitivity to acetylcholine. In-utero exposure decreased the sensitivity (increased the EC50) to the endothelium-independent vasodilator nitroglycerin (p=0.003). CONCLUSIONS: Secondhand smoke has detrimental effects on vascular smooth muscle function in the newborn.

Apoptotic cell death and caspase 3 (CPP32) activation induced by calcium ionophore at low concentrations and their prevention by nerve growth factor in PC12 cells.

A23187 (a calcium ionophore) at low concentration (0.1 microM) induced apoptotic cell death (chromatin condensation and DNA fragmentation) accompanied by the activation of caspase-3 (CPP32), a member of the interleukin-1beta-converting enzyme protease. On the other hand, A23187 at high concentration (2 microM) induced necrotic cell death not accompanied by the activation of CPP32. Nerve growth factor inhibited the cell death and CPP32 activation induced by 0.1 microM A23187, but not the cell death induced by 2 microM A23187. Acylaspartyl-glutamyl-valyl-aspartyl-aldehyde, an inhibitor of CPP32, reduced the cell death induced by 0.1 microM A23187. These results suggest that calcium-ion-induced apoptotic cell death was mediated by CPP32 activation in PC12 cells.

Calcium ionophore-induced secretion from mast cells correlates with myosin light chain phosphorylation by protein kinase C.

Rat basophilic leukemia mast cells (RBL-2H3) secrete histamine when activated by Ag. This secretion correlates with increased phosphorylation of myosin light chain by protein kinase C (PKC). Calcium ionophores (A23187) also elicit secretion, which is enhanced by PMA. To analyze the roles of Ca2+ and PKC in the secretory process, A23187-induced myosin light chain phosphorylation was examined in the presence and absence of PMA. A23187-induced secretion correlated best with myosin light chain phosphorylation by PKC, not with phosphorylation by myosin light chain kinase (MLCK). A23187 induced the translocation to membranes of the alpha, beta, delta, and epsilon isozymes of PKC. PMA not only increased the phosphorylation of myosin light chains at PKC-specific sites (Ser1 and Ser2) but also at sites attributed to MLCK (Ser19 and Thr18-Ser19). A23187 plus PMA induced higher levels of secretion concomitantly with increased myosin light chain phosphorylation at the PKC-specific sites. However, there was little correlation between the translocation of specific PKC isozymes and the phosphorylation of myosin light chains by PKC. Activation induced a novel triphosphorylated form of myosin light chain with a higher level of phosphorylation at the diphosphorylated MLCK sites. Quantitation of A23187 plus PMA-induced myosin light chain phosphorylation revealed that phosphorylation at PKC sites increased from zero to 0.35 mol/mol, was little changed at the monophosphorylated MLCK site (0.30 mol/mol), and increased from zero to 0.06 mol/mol at the diphosphorylated MLCK sites. Therefore, Ca2+-induced secretion correlates best with myosin light chain phosphorylation by PKC, and diphosphorylation by MLCK is unlikely to contribute to secretion.

Selective depression of endothelium-dependent dilations during cerebral ischemia.

BACKGROUND AND PURPOSE: Pial arterioles have diverse mechanisms for endothelium-dependent dilations. In mice, different mechanisms or endothelium-derived mediators exist for each of the following dilators: acetylcholine, bradykinin, and calcium ionophore A-23187. This study tests the response to each of these dilators during profound ischemia. The response to sodium nitroprusside, an endothelium-independent dilator, was also tested. METHODS: In each mouse, ischemia was produced by bilateral carotid artery ligation that reduced cortical blood flow by approximately 90% as determined by laser-Doppler flowmetry. In separate studies of 10 mice each, dilations of pial arterioles to two doses of each dilator were compared before and after 10 minutes of occlusion, with the occlusion continuing during the second set of measurements. The dilator was applied in the suffusate bathing the pial surface exposed at a craniotomy site. Diameters were monitored by in vivo television microscopy and image splitting. RESULTS: The dose-dependent dilations to acetylcholine, bradykinin, and calcium ionophore A-23187 were each profoundly depressed during ischemia. The response to sodium nitroprusside was not depressed. In all cases, the ischemia was accompanied by arteriolar narrowing of approximately 25% and by obvious slowing of blood flow observed by intravital microscopy. Superoxide dismutase plus catalase failed to prevent the depressed response to acetylcholine. CONCLUSIONS: Endothelium-dependent dilations, mediated by diverse endothelium-derived relaxing factors, are depressed during ischemia of 10 to 15 minutes' duration. This cannot be a nonselective effect on vessel responsivity caused by constriction, reduced flow, or reduced intraluminal pressure during ischemia because under the same conditions dilation to endothelium-independent sodium nitroprusside is preserved. The selective endothelial dysfunction may play a role in exacerbating ischemia by precluding the ability of some dilators, released during ischemia, to dilate the resistance vessels.

Inhibition by actinomycin D of neurogenic mouse ear oedema.

We have investigated the effects of actinomycin D on mouse ear oedema induced by capsaicin, neuropeptides, and established inflammatory mediators. Actinomycin D (0.5 mg/kg, i.v.) significantly (P < 0.01) inhibited ear oedema induced by topical application of capsaicin, while adriamycin (6.0 mg/kg, i.v.) and cycloheximide (6.0 mg/kg, i.v.) had no effect on oedema. The ear oedema induced by intradermal injection of neuropeptides such as mammalian tachykinins, calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP), was markedly (P < 0.05, P < 0.01 or P < 0.001) suppressed by actinomycin D. The drug was also effective (P < 0.01 or P < 0.001) in inhibiting bradykinin (BK)- and compound 48/80-induced ear oedema, but did not inhibit oedema induced by histamine, 5-HT, leukotriene C4 (LTC4), and platelet activating factor (PAF) at a dose of 1 mg/kg. In mast cell-deficient W/WV mice, actinomycin D (1.0 mg/kg, i.v.) failed to inhibit substance P (SP)-induced ear oedema whereas spantide (0.5 mg/kg, i.v.) was an effective (P < 0.01) inhibitor of oedema formation. Furthermore, actinomycin D (10-100 microM) dose-dependently prevented histamine release from rat peritoneal mast cells evoked by SP, compound 48/80, and the ionophore A23182, respectively. These results strongly suggest that an inhibitory effect of actinomycin D on neurogenic inflammation is due primarily to the prevention of mast cell activation mediated by neuropeptides, rather than an interaction with DNA or receptors of neuropeptides.