Predicting new-onset heart failure hospitalization of patients with atrial fibrillation: development and external validations of a risk score

Background

Atrial fibrillation (AF) is a well-known risk factor for heart failure (HF), and HF development as a complication of AF is associated with a decline in the quality of life and poor prognosis. However, unlike thrombotic events, incidence of HF in patients with AF has not changed for decades, and a preventive strategy has yet to be developed.

Purpose

We sought to develop a risk model for new-onset HF admission in patients with AF and without a history of HF. Additionally, we attempted to externally validate the developed risk model.

Methods

We utilized two multicenter, prospective, observational registries of AF and analyzed the patients without a history of AF. One of which is defined as a derivation cohort, which included 2,857 patients, and the other is defined as a validation cohort, which included 2,516 patients. We developed a risk model by selecting variables with regularized regression and weighing coefficients by Cox regression analysis with the derivation cohort. The external validity was tested in the validation cohort.

Results

During the follow-up period, 148 patients (5.2%) in the derivation cohort and 104 patients (4.1%) in the validation cohort developed HF during the median follow-up period of 1,396 (interquartile range [IQR]: 1,078–1,820) days and 1,168 (IQR: 844–1,309) days, respectively. In the derivation cohort, four predictors (age, hemoglobin, serum creatinine, and log-transformed brain natriuretic peptide) were identified as potential risk factors for HF development. The developed risk model showed good discrimination and calibration in both the derivation (area under the curve [AUC], 0.77 [95% confidence interval (CI) 0.73–0.81]; Hosmer-Lemeshow test, P=0.257) and validation cohorts (AUC: 0.76 [95% CI 0.72–0.81]; Hosmer-Lemeshow test, P=0.475). Considering death not due to HF as a competing risk, the cumulative incidence curves for HF admission stratified by the risk score were generated, which showed higher HF hospitalization rate for the higher risk score categories.

Conclusion

The newly developed risk model with four readily available clinical characteristics and biomarkers performed well in the prediction of new-onset HF admission of patients with AF in both derivation and validation cohort.

Funding Acknowledgement

Type of funding sources: None.

Property of thimerosal-induced decrease in cellular content of glutathione in rat thymocytes: a flow cytometric study with 5-chloromethylfluorescein diacetate

There is a concern on the part of public health community that adverse health consequences by thimerosal, a preservative in vaccines for infants, may occur among infants during immunization schedule. Therefore, the effect of thimerosal on cellular content of glutathione was examined on thymocytes obtained from 4-week-old rats using a flow cytometer and 5-chloromethylfluorescein diacetate. Thimerosal at concentrations ranging from 1 to 10 microM reduced the cellular content of glutathione in a concentration-dependent manner, and the complete depletion of cellular glutathione was observed when the cells were treated with 30 microM thimerosal. L-Cysteine significantly attenuated the actions of thimerosal to reduce the glutathione content and to increase the intracellular Ca2+ concentration. Prolonged incubation (24 h) with 1-3 microM thimerosal induced the apoptosis. The cytotoxic action of thimerosal was greatly augmented when the cells suffered oxidative stress induced by H2O2. It may be unlikely that thimerosal exerts potent cytotoxic action under the in vivo condition because the blood concentration of thimerosal after receiving vaccines does not seem to reach micromolar range and nonprotein thiols at micromolar concentrations are present in the blood.

Tri-n-butyltin-induced cytotoxicity on rat thymocytes in presence and absence of serum

Influence of fetal bovine serum (FBS) on cytotoxicity induced by tri-n-butyltin (TBT), an environmental pollutant, on rat thymocytes was examined to reveal how FBS modifies TBT cytotoxicity. As the medium FBS concentration was increased from 0 to 10%, the cytotoxicity of TBT was dose-dependently reduced when the cells were incubated with 1 microM TBT for 3 h. Almost complete inhibitions of TBT-induced changes in cell viability and population of cells with exposed phosphatidylserine (cells undergoing apoptosis) were observed when the FBS concentration was 10%. Thus, the cytotoxicity induced by 3 h incubation with TBT in FBS-free medium may be different from that in medium containing 10% FBS. However, even in presence of 10% FBS, TBT at concentrations ranging from 10 to 300 nM exerted cytotoxic action on rat thymocytes when the cells were incubated with TBT for 24 h. TBT dose-dependently increased the population of shrunken cells, of which more than 30% were stained with propidium. TBT at 30 nM or more significantly increased the population of cells with hypodiploid DNA, indicating TBT-induced apoptotic cell death. Thus, in the presence of 10% FBS, the prolonged incubation (24 h) of rat thymocytes with TBT at nanomolar concentrations induced apoptosis rather than necrosis.

Blue-light-dependent osmoregulation in protoplasts of Phaseolus vulgaris Pulvini

Blue light was found to induce shrinkage of the protoplasts isolated from first-leaf lamina pulvini of 18-day-old Phaseolus vulgaris. The response was transient following pulse stimulation, while it was sustainable during continuous stimulation. No apparent difference was found between flexor and extensor protoplasts. Protoplasts of the petiolar segment located close to the pulvinus showed no detectable response. In the plants used, the pulvinus was fully matured and the petiole was ceasing its elongation growth. When younger, 12-day-old, plants were used, however, the petiolar protoplasts did respond to blue light. The pulse-induced response was similar to that in pulvinar protoplasts, although the response to continuous stimulation was transient and differed from that in pulvinar protoplasts. No shrinkage was induced in pulvinar protoplasts when the far-red-light-absorbing form of phytochrome was absent for a period before blue-light stimulation, indicating that the blue-light responsiveness is strictly controlled by phytochrome. Inhibitors of anion channels and H(+)-ATPase abolished the shrinking response, supporting the view that protoplasts shrink by extruding ions. The response of pulvinar protoplasts is probably involved in the blue-light-induced, turgor-based movement of pulvini. The blue-light responding system in pulvini is suggested to have evolved from that functioning in other growing organs.

Cell differentiation and apoptosis of monocytic and promyelocytic leukemia cells (U-937 and HL-60) by tryptanthrin, an active ingredient of Polygonum tinctorium Lour

Tryptanthrin, a bioactive ingredient of Polygonum tinctorium Lour., is a member of the Indigo plant family and has potent cytocidal effects on various human leukemia cells in vitro. At low concentrations, tryptanthrin enhanced the expression of cell differentiation (CD) markers in human monocytic (U-937) and promyelocytic (HL-60) leukemia cells indicative of differentiation to monocytes/macrophages. Furthermore, nitroblue tetrazolium (NBT) reductive and alpha-naphthyl butyrate esterase (NBE) activities were markedly increased after treatment. Tryptanthrin was more potent than dimethyl sulfoxide (DMSO) at inducing U-937 cell differentiation into monocytes/macrophages. After treatment with higher concentrations of tryptanthrin for 24 h, cytoplasmic vacuolation and destruction of mitochondria were observed. The leukemia cells died via apoptosis 48 h after treatment. Cytoplasmic vacuolation and apoptotic changes correlated with the dysfunction of mitochondria. Electron microscopic observations revealed marked swelling and destruction of mitochondria after exposure of the leukemia cells to tryptanthrin. Exposure to tryptanthrin enhanced Fas-induced apoptosis and increased caspase-3 activity before induction of apoptosis. These results show that low concentrations of tryptanthrin can induce differentiation of leukemia cells but higher concentrations will kill leukemia cells through apoptosis, possibly through a caspase-3/Fas antigen pathway.

Identification of essential sequence motifs in the node/notochord enhancer of Foxa2 (Hnf3beta) gene that are conserved across vertebrate species

The expression of a winged-helix transcription factor, Foxa2/HNF3beta, is essential for development of the node and the notochord. We examined the node/notochord enhancer of mouse Foxa2 for sequence motifs conserved across vertebrate species. We cloned Foxa2 genes from chicken and fish, and identified the respective node/notochord enhancers that were active in transgenic mouse embryos. Comparison of the sequences of the enhancers revealed three evolutionally conserved sequence motifs, CS1, CS2 and CS3. Mutational analysis of the mouse enhancer indicated that CS3 is indispensable for gene expression in the node and the notochord, while CS1 and CS2 are required to augment enhancer activity. These motifs do not correspond to the consensus binding sequences of transcription factors known to be involved in node/notochord development.

A case of acute pulmonary embolism and acute myocardial infarction with suspected paradoxical embolism after laparoscopic surgery

We describe the case of a 59-year-old Japanese man who had an acute pulmonary embolism in addition to acute myocardial infarction after a laparoscopic cholecystectomy. The posterior descending coronary artery was totally occluded. and direct percutaneous transluminal balloon angioplasty was performed. The pulmonary embolism was diagnosed by lung perfusion scanning and was treated with anticoagulant therapy. A patent foramen ovale and right-to-left atrial shunting of blood were detected by contrast transesophageal echocardiography. Paradoxical embolism is a rare complication of pulmonary embolism and may have been responsible for the acute myocardial infarction in our patient.

A pulse of blue light induces a transient increase in activity of apoplastic K+ in laminar pulvinus of Phaseolus vulgaris L

A pulse of blue light induced both a transient increase in activity of apoplastic K+ and membrane depolarization in laminar pulvinus of Phaseolus vulgaris L. This shows that blue-light-induced net efflux of K+ from motor cells is closely related to membrane depolarization.

Mouse suppressor of fused is a negative regulator of sonic hedgehog signaling and alters the subcellular distribution of Gli1

The Hedgehog (Hh) signaling pathway has critical functions during embryogenesis of both invertebrate and vertebrate species [1]; defects in this pathway in humans can cause developmental disorders as well as neoplasia [2]. Although the Gli1, Gli2, and Gli3 zinc finger proteins are known to be effectors of Hh signaling in vertebrates, the mechanisms regulating activity of these transcription factors remain poorly understood [3] [4]. In Drosophila, activity of the Gli homolog Cubitus interruptus (Ci) is likely to be modulated by its interaction with a cytoplasmic complex containing several other proteins [5] [6], including Costal2, Fused (Fu), and Suppressor of fused (Su(fu)), the last of which has been shown to interact directly with Ci [7]. We have cloned mouse Suppressor of fused (mSu(fu)) and detected its 4.5 kb transcript throughout embryogenesis and in several adult tissues. In cultured cells, mSu(fu) overexpression inhibited transcriptional activation mediated by Sonic hedgehog (Shh), Gli1 and Gli2. Co-immunoprecipitation of epitope-tagged proteins indicated that mSu(fu) interacts with Gli1, Gli2, and Gli3, and that the inhibitory effects of mSu(fu) on Gli1's transcriptional activity were mediated through interactions with both amino- and carboxy-terminal regions of Gli1. Gli1 was localized primarily to the nucleus of both HeLa cells and the Shh-responsive cell line MNS-70; co-expression with mSu(fu) resulted in a striking increase in cytoplasmic Gli1 immunostaining. Our findings indicate that mSu(fu) can function as a negative regulator of Shh signaling and suggest that this effect is mediated by interaction with Gli transcription factors.

Regulation of Gli2 and Gli3 activities by an amino-terminal repression domain: implication of Gli2 and Gli3 as primary mediators of Shh signaling

Gli family zinc finger proteins are mediators of Sonic hedgehog (Shh) signaling in vertebrates. The question remains unanswered, however, as to how these Gli proteins participate in the Shh signaling pathway. In this study, regulatory activities associated with the Gli2 protein were investigated in relation to the Shh signaling. Although Gli2 acts as a weak transcriptional activator, it is in fact a composite of positive and negative regulatory domains. In cultured cells, truncation of the activation domain in the C-terminal half results in a protein with repressor activity, while removal of the repression domain at the N terminus converts Gli2 into a strong activator. In transgenic mouse embryos, N-terminally truncated Gli2, unlike the full length protein, activates a Shh target gene, HNF3beta, in the dorsal neural tube, thus mimicking the effect of Shh signal. This suggests that unmasking of the strong activation potential of Gli2 through modulation of the N-terminal repression domain is one of the key mechanisms of the Shh signaling. A similar regulatory mechanism involving the N-terminal region was also found for Gli3, but not for Gli1. When the Shh signal derived from the notochord is received by the neural plate, the widely expressed Gli2 and Gli3 proteins are presumably converted to their active forms in the ventral cells, leading to activation of transcription of their target genes, including Gli1.

Absence of R1066X mutation in six Japanese patients with Dubin-Johnson syndrome

The Dubin-Johnson syndrome (DJS) is a rare autosomal recessive liver disease characterized by chronic conjugated hyperbilirubinemia. The phenotype of this syndrome is thought to be caused by the impaired expression of the canalicular multispecific organic anion transporter (cMOAT), which transports non-bile salt organic anions into the bile. Recently, a mutation from arginine (Arg) to stop-codon at codon 1066 in the cMOAT gene has been reported in one Caucasian patient with DJS. In this study, we investigated whether this mutation is found in Japanese patients with DJS. Genomic DNAs were extracted from the leukocytes of six Japanese patients and the fragments spanning codon 1066 were amplified by polymerase-chain reaction. The digest of the amplified fragments with a restriction enzyme, Taql, demonstrated that all of six patients did not exhibit an R1066X mutation. No mutation at Arg1066 was also confirmed by direct sequencing of the amplified products. These findings suggested that this R1066X mutation was not a major mutation in Japanese patients with DJS. Further investigation will be required in an attempt to search other mutations in cMOAT gene in Japanese patients with DJS.

Mechanisms of hepatic microcirculatory disturbances induced by acute ethanol administration in rats, with special reference to alterations of sinusoidal endothelial fenestrae

Elucidation of the hepatic hemodynamics in acute ethanol administration is an issue of clinical importance for better understanding of alcoholic liver diseases. The purpose of this study is to clarify the mechanism of hepatic microcirculatory disturbances after acute ethanol administration, especially regarding the effects of ethanol on alterations of sinusoidal endothelial fenestrae (SEF) and the involvement of endothelin-1 (ET-1) in the mechanism of portal hypertension induced by ethanol. Ethanol was administrated into the portal vein via the mesenteric vein branch of rats as a continuous infusion (4 and 8 mg/min of ethanol) for 60 min. Hepatic tissue blood flow measured with a laser Doppler blood flowmeter was found to be remarkably decreased with time, whereas portal pressure began to increase at 10 min and showed a significant increase by approximately 1.5 cm H2O at 60 min. Ethanol concentrations in blood at 60 min after 4 and 8 mg/min of ethanol infusion were 0.75 mg/ml and 1.77 mg/ml, respectively. At this point, scanning electron microscopy revealed significant decreases in number and diameter of SEF both in zone 1 and zone 3, with the increase in ethanol level. These findings suggested that decreases in number and diameter of SEF, whether primary or secondary, may lead to the impairment of the transport of plasma substances from sinusoids to hepatocytes in acute ethanol administration. Furthermore, the pretreatment of BQ-123 inhibited a decrease in hepatic tissue blood flow and an increase in portal pressure caused by ethanol, indicating that ET-1 may be involved in the mechanism of hepatic circulatory disturbances in acute ethanol administration.

An enzyme immune assay for serum anti-acetaldehyde adduct antibody using low-density lipoprotein adduct and its significance in alcoholic liver injury

An acetaldehyde (AcH) adduct was prepared using rabbit low-density lipoprotein as carrier proteins. An antibody against this adduct was raised in Watanabe heritable hyperlipidemic rabbits and cross-reacted with human low-density lipoprotein and bovine serum albumin adducts. Using this antibody, serum anti-AcH-adduct antibody levels were measured by a direct ELISA method in 56 Japanese adults (healthy adults and patients with nonalcoholic gastrointestinal diseases, alcoholic liver injury, or alcoholic pancreatitis). The antibody level (mean +/- SD) was 22 +/- 10 microg/ml in healthy adults, 22 +/- 11 microg/ml in nonalcoholic gastrointestinal diseases, and 16 +/- 13 microg/ml in alcoholic pancreatitis. These antibody levels tended to increase with the progression of alcoholic liver injury, starting from fatty liver via hepatitis to cirrhosis, 29 +/- 24 microg/ml in fatty liver, 35 +/- 29 microg/ml in alcoholic hepatitis, and 46 +/- 54 microg/ml in alcoholic cirrhosis. The antibody level in patients taking 100 g or more of ethanol per day tended to be higher, compared with those in people taking less ethanol. A follow-up observation revealed that alcohol abstinence after hospitalization raised serum anti-AcH-adduct antibody level in some patients and kept it constantly low in other patients. The immunohistochemical study using the anti-AcH-adduct antibody revealed the presence of adduct-like substance in hepatocytes of liver biopsy specimens obtained from patients with alcoholic liver disease. The results indicate that the anti-AcH-adduct antibody may be associated with the progress of alcoholic liver diseases.

Differential expression of multidrug resistance (mdr) and canalicular multispecific organic anion transporter (cMOAT) genes following extrahepatic biliary obstruction in rats

The hepatic canalicular membrane has transporters that play an important role as efflux pumps in the excretion of endogenous bile constituents or xenobiotics into bile canaliculi. To elucidate functional significance of canalicular transporters in the mechanism of cholestasis, mRNA expression levels of multidrug resistance (mdr) 1b, mdr2 and canalicular multispecific organic anion transporter (cMOAT) genes were analyzed by Southern blotting of reverse-transcribed PCR products of liver mRNA obtained from cholestatic rats that had been subjected to bile duct ligation. Both mdr1b and mdr2 mRNA expression increased after ligation. Immunohistochemical study revealed that the products of both mdr1b and mdr2 were present on the canaliculi, and that their levels increased after ligation. In contrast, cMOAT mRNA expression was not increased, but rather attenuated by ligation. The expression of canalicular transporters was differentially regulated in extrahepatic biliary obstruction, indicating the different roles are played by mdr and cMOAT in the pathogenesis of cholestasis.

Comparison of two interferon alfa treatment regimens characterized by an early virological response in patients with chronic hepatitis C

OBJECTIVE

We investigated the efficacy of an interferon regimen characterized by an early virological response in patients with chronic hepatitis C and evaluated whether the patient's virological status during therapy would be useful for predicting a complete response.

METHODS

We treated 62 patients with chronic hepatitis C with 6 million units (MU) of human lymphoblastoid interferon daily for 4 wk. The serum HCV RNA was assayed at week 2 by the reverse transcription-polymerase chain reaction. HCV RNA-negative patients (group A) received 6 MU of interferon three times weekly for an additional 22 wk (total dose, 564 MU). HCV RNA-positive patients were randomly assigned to group B-1, which received the same regimen as group A, or to group B-2, which received 6 MU of interferon daily for 4 wk followed by 6 MU three times weekly for 18 wk (total dose, 660 MU).

RESULTS

Complete responses were achieved by 19 (63.3%) of 30 group A patients, compared with one (6.3%) of 16 group B-1 patients and none of 16 group B-2 patients. The virological response at week 2 and the pretreatment serum HCV RNA level were independent significant predictors of a complete response.

CONCLUSION

Patients who were still HCV RNA-positive at week 2 were unlikely to achieve a complete response after interferon therapy. An increase in the total dose of interferon failed to yield further benefit in these patients.

Cellular and molecular mechanisms of IL-5 synthesis in atopic diseases: a study with allergen-specific human helper T cells

BACKGROUND

Cytokines produced by helper T cells are intimately involved in chronic allergic diseases associated with eosinophilic inflammation.

OBJECTIVE

We investigated the production of IL-5, a potent growth factor and chemotactic factor for eosinophils, by CD4+ T lymphocytes in patients with asthma.

METHODS

Allergen-specific T cell clones and T cell hybridomas were established from the peripheral blood lymphocytes of patients with asthma, and the responses to various stimuli were determined.

RESULTS

After nonspecific stimulation, IL-5 production by CD4+ T cells from both atopic and nonatopic subjects with asthma was significantly enhanced compared with that by cells from healthy controls. Peripheral blood mononuclear cells from atopic asthma patients both proliferated and produced IL-5 after incubation with mite allergen, suggesting that mite-specific helper T cells were involved in the eosinophilic inflammation of atopic asthma. A human IL-5 promoter/enhancer luciferase gene construct transfected into IL-5-producing T cell clones was clearly transcribed after stimulation, indicating that the 515 base pair IL-5 gene segment upstream of the coding region was sufficient to respond to activating signals in human helper T cells. The same gene segment was not transcribed in IL-5-nonproducing T cell clones, suggesting that human T cell IL-5 synthesis is regulated at the transcriptional level. Experiments with T cell hybridomas confirmed these findings and suggested that a unique transcription factor may be essential for human IL-5 gene transcription.

CONCLUSION

Enhanced IL-5 production by helper T cells seems to cause the eosinophilic inflammation of both atopic and nonatopic asthma. Elucidation of IL-5-specific regulatory mechanisms may facilitate the development of novel treatments for allergic diseases associated with eosinophilic inflammation.

Immunohistochemical and immuno-electron-microscopic detection of interferon-gamma-inducing factor ("interleukin-18") in mouse intestinal epithelial cells

The novel cytokine interferon-gamma-inducing factor ("interleukin-18") is produced by macrophage-like cells in mice with endotoxin shock and induces the production of interferon-gamma by T cells in vitro. To determine the physiological role for mouse interferon-gamma-inducing factor, we studied its tissue distribution in several organs (intestine, spleen, thymus, kidney, and liver) in healthy mice of different ages, including fetal stages. Activity of the cytokine in the organ extracts of adult mice was measured by enzyme-linked immunosorbent assay, and the cellular distribution of interferon-gamma-inducing factor in organs from fetal and adult mice was determined by immunohistochemistry. Intestinal extracts of adult mice showed the highest concentrations among the organs studied. Other organ extracts of adult mice showed lower concentrations of the cytokine. Immunohistochemical analysis revealed that interferon-gamma-inducing factor was localized in the cytoplasm of intestinal epithelial cells from fetal and adult mice. These results show for the first time that intestinal epithelial cells may be the main producers of interferon-gamma-inducing factor under normal physiological conditions and suggest that its constitutive expression in intestinal epithelial cells may have an important role in the induction of mucosal immunity.

A critical role of IL-2 for the production and gene transcription of IL-5 in allergen-specific human T cell clones

The role of IL-2 in IL-5 synthesis of human helper T cells was investigated. All of the Der f II (a major allergen of house dust mite)-specific T cell clones established from atopic asthmatic patients produced both IL-2 and IL-4 upon activation (Th0 phenotypes). Recombinant IL-2 induced gene expression and protein synthesis of IL-5 in T cell clones that produced IL-5 upon antigenic stimulation. Human IL-5 promoter/enhancer-luciferase gene construct transfected to T cell clones was clearly transcribed in response to IL-2, indicating that the approximately 500 bp gene segment 5' upstream of the coding region was functionally sufficient for the gene transcription induced by IL-2. IL-2-induced IL-5 synthesis as well as proliferation was dependent on tyrosine kinases. Moreover, IL-5 production by T cell clones stimulated with immobilized anti-CD3 antibody was completely abrogated by anti-IL-2 neutralizing antibody, suggesting that IL-5 (a Th2 cytokine) synthesis of human helper T cells is dependent on IL-2 (a Th1 cytokine). Our present findings clearly demonstrated that IL-2, known as a T cell growth factor, exerts a cytokine promoting activity on T cells. IL-2 produced at the site of allergic inflammation might facilitate eosinophilic inflammation by inducing IL-5 production in T cells.

IL-15 promotes cytokine production of human T helper cells

IL-15 is a newly identified cytokine that has T cell and B cell growth factor activity similar to that of IL-2. In this study, a novel biologic function of IL-15 to promote cytokine production by human Th cells has been elucidated. Dermatophagoides farinae 11 (a major allergen of house dust mite)-specific human T cell clones produced IL-5 in response to recombinant human IL-15 as well as to either anti-CD3 or IL-2 stimulation. IL-5 mRNA became detectable 3 h after IL-15 stimulation and reached a maximum at 9 h. Human IL-5 promoter/enhancer-luciferase gene construct transfected to T cell clones was clearly transcribed in response to IL-15, indicating that the approximately 500-bp human IL-5 promoter/enhancer segment 5' upstream of the coding region sufficiently responded to IL-15. IL-15-induced IL-5 synthesis was completely inhibited by the tyrosine kinase inhibitor, herbimycin A, suggesting the involvement of tyrosine kinases in the signal transduction leading to IL-5 synthesis as well as to proliferation of T cells induced by IL-15. Whereas IL-5 production by human peripheral T cells was abolished by the addition of anti-IL-2-neutralizing Abs into the culture, IL-15 restored the IL-5 synthesis despite effective IL-2 neutralization. IL-15 produced at the site of allergic inflammation may play a role in the recruitment and activation of eosinophils by inducing IL-5 (a Th2 cytokine) production by T cells.

IL-15 promotes cytokine production of human T helper cells

IL-15 is a newly identified cytokine that has T cell and B cell growth factor activity similar to that of IL-2. In this study, a novel biologic function of IL-15 to promote cytokine production by human Th cells has been elucidated. Dermatophagoides farinae 11 (a major allergen of house dust mite)-specific human T cell clones produced IL-5 in response to recombinant human IL-15 as well as to either anti-CD3 or IL-2 stimulation. IL-5 mRNA became detectable 3 h after IL-15 stimulation and reached a maximum at 9 h. Human IL-5 promoter/enhancer-luciferase gene construct transfected to T cell clones was clearly transcribed in response to IL-15, indicating that the approximately 500-bp human IL-5 promoter/enhancer segment 5' upstream of the coding region sufficiently responded to IL-15. IL-15-induced IL-5 synthesis was completely inhibited by the tyrosine kinase inhibitor, herbimycin A, suggesting the involvement of tyrosine kinases in the signal transduction leading to IL-5 synthesis as well as to proliferation of T cells induced by IL-15. Whereas IL-5 production by human peripheral T cells was abolished by the addition of anti-IL-2-neutralizing Abs into the culture, IL-15 restored the IL-5 synthesis despite effective IL-2 neutralization. IL-15 produced at the site of allergic inflammation may play a role in the recruitment and activation of eosinophils by inducing IL-5 (a Th2 cytokine) production by T cells.

A novel phosphodiesterase inhibitor, T-440: possible management of eosinophilic inflammation by down-regulation of interleukin-5 production

The effect of T-440, a selective type IV phosphodiesterase (PDE IV) inhibitor on interleukin (IL)-5 production by peripheral blood mononuclear cells (PBMCs) of atopic asthmatic subjects was investigated. PBMCs produced IL 5 following challenge with specific allergen in vitro. T-440 suppressed allergen-induced IL-5 production significantly at a concentration of 1 microgram/ml. T-440 inhibited cyclic AMP-phosphodiesterase (PDE) activity in a concentration dependent manner and raised the intracellular cyclic AMP level of PBMCs significantly. Dibutyryl cyclic AMP suppressed IL-5 production by PBMCs in a similar way to T-440, suggesting that the increase of intracellular cyclic AMP caused by T-440 reduces IL-5 production. T-440 may be an effective agent to treat atopic diseases associated with eosinophilic inflammation, e.g. asthma and atopic dermatitis.

Impairment of the gastric hyperemic response to luminal acid in cirrhotic rats

Liver cirrhosis impairs gastric mucosal resistance to luminal acid in humans and in animal models. Because we have previously shown that pentagastrin enhances defensive as well as aggressive factors implicated in mucosal injury, we examined the hypothesis that the pentagastrin-mediated enhancement of mucosal defense mechanisms may be impaired in cirrhotic rats. Increased acid backdiffusion and susceptibility to gross mucosal injury, associated with an elimination of the hyperemic response to gastric barrier disruption, was observed in cirrhotic rats. In in vivo microscopic studies in anesthetized rats, cirrhosis had no effect on pentagastrin-associated enhancement of mucus gel thickness or baseline gastric mucosal blood flow, although baseline mucus gel thickness was decreased. Cirrhosis did, however, abolish the luminal acid-related hyperemic response to pentagastrin, which was associated with impaired intracellular pH homeostasis during acid superfusion. Cirrhosis did not alter submucosal calcitonin gene-related peptide immunoreactive nerves. We conclude that acid backdiffusion and pentagastrin-associated hyperemic responses are important mucosal defensive factors that are specifically impaired by cirrhosis.

Barrier function of the gastric mucus gel

The gastric epithelium is covered by a continuous layer of secreted mucus and bicarbonate. The function of this mucobicarbonate layer in terms of protecting the epithelial cells from luminal acid is controversial. Several studies conducted in vitro have shown that gastric mucus can slow proton diffusion and can enable the formation of a pH gradient across the mucobicarbonate layer. In our laboratory, simultaneous measurements of intracellular pH and the thickness of the mucus gel overlying gastric surface cells in vivo indicated that surface cell acidification rates and mucus gel thickness were inversely related. This suggests that the gastric mucobicarbonate layer delays proton permeation into gastric surface cells, enabling secreted bicarbonate to neutralize luminal acid. Several theoretical models, including the effects of mucus and bicarbonate secretion, convection, stirring, and lipids are offered as a possible explanation for the experimental observations. Lipid content and additional unstirred layers outside of the mucus gel are offered as possible explanations for the experimental observations. On the basis of the available data and theoretical considerations, we can conclude that all of these factors probably interact in an integrated manner to protect the gastric epithelial cells from damage due to luminal acid.

Allergen-specific human T cell clones produce interleukin-5 upon stimulation with the Th1 cytokine interleukin-2

CD4+ T cell clones specific for Der fII (a major allergen of the house dust mite) were established from peripheral blood mononuclear cells of atopic patients. All of the T cell clones were classified as having the Th0 phenotype, since they produced both interleukin (IL)-2 and IL-4 upon stimulation. Some of the clones produced IL-5 upon antigenic stimulation. Human recombinant IL-2 induced these T cell clones to express IL-5 mRNA and produce IL-5 protein in a dose-dependent manner. IL-2 did not induce IL-4 production, indicating a discrete signal requirement for IL-4 versus IL-5 production by T cells. Moreover, IL-5 production induced by immobilized anti-CD3 monoclonal antibody was completely suppressed by the addition of anti-IL-2 monoclonal antibody, suggesting that IL-5 production, designated as a Th2-type immune response, is dependent on IL-2, a Thl cytokine. IL-2 produced at the site of allergic inflammation may contribute to IL-5 production by T cells in vivo.

IL-5 production by CD4+ T cells of asthmatic patients is suppressed by glucocorticoids and the immunosuppressants FK506 and cyclosporin A

IL-5 was produced in vitro by peripheral blood mononuclear cells (PBMC) of mite-sensitive atopic patients upon challenge with specific allergen, while PBMC of healthy controls produced essentially no IL-5. Stimuli delivered by the combination of phorbol ester and Ca2+ ionophore induced marked IL-5 production by PBMC obtained from atopic and non-atopic asthmatics, suggesting that both protein kinase C and Ca2+ influx are required for IL-5 production. CD2- or CD4-bearing cell depletion almost completely removed IL-5-producing cells while CD8-bearing cell depletion rather enriched them. These findings indicate that CD4+ T cells are the principal source of IL-5 in PBMC. The capacity of PBMC of atopic asthmatics, non-atopic asthmatics and healthy controls to produce IL-2, IL-4, IL-5 and IFN-gamma was compared, to find that cytokine-producing capacities other than that of IL-5 (IL-2, IL-4 and IFN-gamma) were not significantly different among the three groups. Dexamethasone, FK506 and cyclosporin A suppressed IL-5 production in vitro in a dose-dependent manner. Clear dose-dependent suppression of IL-5 gene expression by FK506 was also observed. Treatment of asthmatic patients with inhaled glucocorticoid (beclomethasone dipropionate) ameliorated clinical symptoms, improved lung function and markedly suppressed IL-5 production by PBMC, suggesting the essential role of IL-5 in the pathogenesis of bronchial asthma and the clinical importance of its regulation.

[Relationship between myocardial perfusion state immediately after reperfusion therapy and left ventricular wall motion improvement in patients with acute myocardial infarction]

The relationship between myocardial contrast echocardiography and improvement of the left ventricular wall motion was studied as an indicator of the prognosis of patients with acute myocardial infarction. Ten patients with acute anterior myocardial infarction who demonstrated successful reperfusion (improved to TIMI grade III) and patency of the responsible coronary artery during the chronic stage (one month after the onset) were selected. The contrast study used 2 ml of sonicated iopamidol injected into the left coronary artery. Two-dimensional echocardiograms were taken at the level of papillary muscle on the short axis for recording in VTR. The results of the contrast study were evaluated using a contrast defect score based on the degree and width of the contrast defect. Percent wall motion improvement was measured as an index of improvement of the left ventricular wall motion and CKmax was used for estimating the extent of myocardial necrosis. There was a good correlation between contrast defect score and CKmax (r = 0.853) or % wall motion improvement (r = 0.77). No correlation was found between coronary occlusion time and CKmax nor between coronary occlusion time and % wall motion improvement. The results suggest that if the score is high, recovery of left ventricular wall motion cannot be expected in patients with acute myocardial infarction who demonstrate successful reperfusion. In such cases, myocardial perfusion has not been effectively restored and myocardial necrosis extended over a wide area. If the score is low, recovery of the wall motion can be expected in the chronic stage even though abnormal left ventricular wall motion area is extensive immediately after reperfusion therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin E2 enhances gastric defense mechanisms against acid injury in uremic rats

BACKGROUND/AIMS

Uremia increases gastric mucosal H+ permeability and acid back-diffusion-related injury in rats. The aim of this study was to examine the effect of the synthetic gastroprotective compound 16,16-dimethyl prostaglandin E2 (16,16-dm PGE2) on the gastric barrier to acid injury in uremic rats.

METHODS

Chronic renal failure was induced by subtotal nephrectomy. Acid back-diffusion injury was induced by superfusion with 15% ethanol in 0.15N HCl and was assessed by image analysis. Intracellular pH, initial surface cell acidification rate, and thickness of mucous gel layer were measured with in vivo microscopy. Gastric mucosal blood flow was measured in separate experiments by laser-Doppler flowmetry.

RESULTS

Pretreatment with 16,16-dm PGE2 attenuated H+ back-diffusion and prevented the production of gross lesions. 16,16-dm PGE2 increased gastric mucous gel thickness, decreased initial acidification rate, and maintained intracellular pH homeostasis during exposure to luminal acid. Gastric mucosal blood flow was not changed during superfusion with a neutral buffer but increased during acid exposure in rats treated with 16,16-dm PGE2.

CONCLUSIONS

16,16-dm PGE2 attenuated H+ back-diffusion injury in uremic rats. This effect was associated with blunting of the initial decrease of intracellular pH and enhanced surface cell intracellular pH homeostasis during acid exposure. These effects were associated with an increased mucous gel layer thickness and an acid-related increase in blood flow.

Impairment of gastric mucosal defenses measured in vivo in cirrhotic rats

Patients with cirrhosis have an increased incidence of gastric ulcers and erosions. We evaluated the effect of carbon tetrachloride-induced cirrhosis on rat gastric mucosal defense mechanisms using our recently developed in vivo fluorescence microscopy technique. Cirrhotic rats had increased portal vein pressure, increased serum aminotransferase concentrations and decreased serum albumin concentrations. We noted significantly more spontaneous gross gastric lesions in the cirrhotic rats. In vivo microscopic measurements revealed that cirrhotic rats had (a) a significantly thinner gastric mucous gel layer, (b) a much greater decrease in surface mucosal cell intracellular pH in response to an acid load, (c) decreased gastric mucosal blood flow and (d) decreased surface cell viability. We conclude that spontaneous gastric mucosal lesions in cirrhotic rats may be related to more rapid penetration of acid through a thinner gastric mucous gel layer and a lower mucosal blood flow. These changes are associated with a decreased ability of the surface cells to maintain intracellular pH homeostasis, increased initial gastric surface cell acidification, decreased surface cell viability and a lower blood flow that probably is inadequate to remove the increased acid.

Pentagastrin enhances gastric mucosal defenses in vivo: luminal acid-dependent and independent effects

Stimulation of acid secretion is associated with enhanced resistance of the gastric mucosa to damage by luminal acid. We studied the mechanism by which gastric mucosal defenses are modulated in a system in which mucus gel thickness, intracellular pH (pHi), gastric mucosal blood flow, and acid secretion can be measured simultaneously in vivo, using a recently developed microfluorometric technique. Intravenous infusion of pentagastrin in a dose associated with maximal acid secretion increased mucus gel thickness, pHi, and mucosal blood flow during superfusion with a neutral solution. Subsequent superfusion with an acidic buffer (pH 1.7) further increased blood flow to nearly three times basal. During superfusion with luminal acid, pHi fell more slowly and recovered toward baseline more quickly in pentagastrin-infused rats than in controls. Pretreatment with the H2-receptor antagonist cimetidine abolished the increased blood flow associated with pentagastrin, impairing pHi homeostasis, although cimetidine increased mucus gel thickness in the absence of pentagastrin. We conclude that gastric defense mechanisms at the preendothelial and postepithelial levels are enhanced during acid secretion as part of a histamine-dependent homeostatic mechanism that balances gastric protective mechanisms with acid secretion. The net result of these enhanced defenses is the preservation of gastric surface cell pHi despite the presence of a large proton gradient between lumen and blood.

Regulation of interleukin-5 production by peripheral blood mononuclear cells from atopic patients with FK506, cyclosporin A and glucocorticoid

Upon stimulation with phorbol ester and ionomycin, peripheral blood mononuclear cells (PBMC) of atopic patients with moderate eosinophilia produced significantly higher amounts of IL-5 compared to that of normal subjects. This finding renders further support to the notion that T cell-eosinophilic inflammation plays a central role in allergic disorders. IL-5 induction in vitro was completely inhibited by immunosuppressant FK506, cyclosporin A and dexamethasone. FK506 applied in vivo effectively suppressed clinical symptoms of atopic dermatitis and IL-5 production of PBMC. FK506 and cyclosporin A may become a better therapeutic modality against allergic diseases.

Isoproterenol enhances rat gastric mucosal barrier function in vivo

BACKGROUND

The mechanism by which topical isoproterenol protects the gastric mucosa from ethanol-induced injury is unclear; previous studies suggest that enhancement of mucosal blood flow may be contributory. Therefore, we investigated the role of isoproterenol pretreatment on rat gastric mucous gel layer thickness, mucosal blood flow, and surface cell intracellular pH.

METHODS

A portion of the gastric corpus of an anesthetized rat was isolated in a superfused chamber. Intracellular pH was measured with the fluorescent dye 5(6)-carboxyfluorescein diacetate, mucous gel thickness was measured by quantifying the distance between the focal planes of the epithelial cell and the gel surfaces, and mucosal blood flow was measured in separate experiments with a laser-Doppler flowmeter.

RESULTS

Pretreatment with topical isoproterenol markedly increased gastric mucous gel layer thickness, decreased surface cell initial acidification rates, and significantly enhanced the recovery of intracellular pH toward baseline values. Gastric mucosal blood flow was significantly higher in the isoproterenol-treated group compared with untreated controls, initially increasing, decreasing, and then increasing a second time during superfusion with acidic solutions.

CONCLUSIONS

Isoproterenol preserves gastric surface cell intracellular pH during acid superfusion. This effect may be a result of an increased thickness of the mucous layer, which delays proton entry into the surface cell, and an increase in mucosal blood flow in response to luminal acid, which appears to enhance recovery from intracellular acidosis.

[The effects of exogenous and endogenous dopamine on the gastric microcirculation and their action sites in rat stomach]

The effect of exogenous and endogenous dopamine on the gastric microcirculation and their action sites on stomach were investigated by laser Doppler flowmetry, histochemistry, electron microscopy and radioautography. The effects of graded doses of dopamine on the gastric mucosal blood flow were different from those on the systemic blood flow, implying that there may exist a dopaminergic control of gastric mucosal blood flow independent from the systemic circulation. By histochemical observations of the horseradish peroxidase (HRP) infused preparations, HRP was found to be distributed mainly to the arterioles and venules at the base of the gastric mucosa with a high dose of dopamine which may contributed to open the arterio-venular shunt either at the base of mucosa or in the submucosa. Pretreatment with monoamine oxidase inhibitor and/or 6-hydroxydopamine caused changes in the levels of endogenous catecholamine (dopamine, noradrenaline and adrenaline) in the stomach wall. An imbalanced catecholamine in the stomach wall, particularly an increase in DA, decreased gastric mucosal blood flow. Radioautographic studies revealed that D1-receptors are located mainly on the arterioles in the lower part of the mucosa and submucosa, while D2-receptors are located mainly on the muscularis mucosae and on the collecting venules. Tyrosine hydroxylase (TH) positive nerve fibers possibly corresponding to the dopaminergic fiber were evident in the vicinity to the arterioles, venules, and muscularis mucosae. Some TH-positive fibers were extended to the true capillaries in the mucosa. Dopamine beta-hydroxylase positive fibers were noted near the arterioles and venules both in the submucosa and the lower portion of mucosal layer. Based on the above results, the dopaminergic mechanisms are considered to be involved in the regulation of the gastric mucosal microcirculation through the dopaminergic nerves.

Effect of orogastric nicotine on rat gastric mucosal gel thickness, surface cell viability and intracellular pH

Intracellular pH was measured in vivo using a fluorescent, microscopic technique in gastric surface cells of rats exposed to orogastric nicotine on an acute or chronic basis. Mucosae were superfused with solutions of pH 3 or pH 1.7 in order to examine the rate of intracellular acidification and recovery. In rats acutely exposed to nicotine, the response of intracellular pH to superfusion with acidic solutions was blunted with respect to control rats in a dose-dependent manner. In contrast, intracellular pH of rats chronically treated with nicotine had an exaggerated response with respect to control rats, with more rapid acidification and diminished ability to maintain intracellular pH in the physiologic range. Mucus gel thickness was increased after acute nicotine exposure in a dose-dependent manner, whereas a dose-dependent decrease in thickness was seen after chronic nicotine exposure. Cell viability using the fluorescent vital dye propidium iodide was increased in rats acutely treated with orogastric nicotine; conversely, viability was decreased in chronically treated rats. We conclude that acute nicotine exposure diminishes, whereas chronic nicotine exposure enhances, the effect of luminal acidity on mucosal surface cell intracellular pH and cell viability. These divergent effects correlate inversely with mucus gel thickness, suggesting that the mucus gel layer is an important component of the gastric mucosal barrier.

[A study on normal coronary arteriogram by provocation and spontaneous anginal attack: 4 cases of ST elevated angina with normal coronary arteries by provoked and spontaneous attacks]

During 3 years and 5 months, we experienced 3 of 172 cases of provocations on normal coronary arteries which presented ST elevated angina by ergonovine provocations. The incidence was 2.5% and 4% for all ergonovine provocations and intracoronary ergonovine provocations respectively. One case presented spontaneous attack in coronary arteriography, indicating similar state to occur not only with provocation but also in spontaneous attack. Examination of literature revealed no apparent report on such cases as this. For pathogenesis, the possibility of changes of small vessels was suggested in view of various literature and its specificity to the coronary arterial region.

Uremia increases gastric mucosal permeability and acid back-diffusion injury in the rat

The possibility that chronic uremia renders the gastric mucosa more susceptible to acid injury was investigated. A rat model of chronic renal failure was induced by subtotal nephrectomy. [H+] back-diffusion across the mucosa, following intragastric perfusion of 0.15N HCl or 15% ethanol in 0.15N HCl, was significantly greater in uremic than in sham-operated rats. Gastric mucous gel thickness and transmural potential difference were significantly lower in rats with renal insufficiency. Furthermore, a significantly greater acidification rate of the surface epithelial cells was found in uremic rats than in sham-operated rats during superfusion with pH 1.7 buffer. Intragastric administration of acidified ethanol or aspirin solutions markedly increased gastric mucosal blood flow (68% and 89% respectively) in the sham-operated group producing mild injury, in contrast to uremic rats, where a lesser increase in mucosal blood flow (7% and 14% respectively) was associated with more pronounced mucosal injury. It was concluded that enhanced susceptibility to acid injury in uremia is due to a reduction of function of pre-epithelial, epithelial, and postepithelial elements of the gastric mucosal barrier.

Cushing's syndrome due to primary pigmented nodular adrenocortical disease with cardiac myxomas and mucocutaneous lentigines

A young Japanese female demonstrated unusual features of Cushing's syndrome, cardiac myxomas and mucocutaneous lentigines. At the age of 12 years she presented with growth failure and obesity. The dexamethasone suppression test, the metyrapone test and low corticotropin concentrations indicated a primary adrenal disorder. At surgery, the adrenal glands were not enlarged (the right, 4.0 g; the left; 4.5 g) but had numerous small dark brown nodules. The pathological findings showed multiple small black cortical nodules containing large cells with eosinophilic cytoplasm and lipofuscin, and internodular cortical atrophy. These abnormalities were consistent with primary pigmented nodular adrenocortical disease. At age 22 years she complained of fatigue and palpitations associated with mid-chest pain. Four cardiac myxomas, suspected from the echocardiogram, were surgically removed. Because Cushing's syndrome and cardiac myxomas are life-threatening conditions, an awareness of the complex is important.

Roles of muscularis mucosae and myofibroblasts in the healing process of acetic acid-induced ulcer

The changes in the localization of FITC-phalloidin-positive smooth muscle cells and interstitial cells were studied in control and acetic acid-treated rat fundic mucosa. In the control rats, the FITC-phalloidin-positive cells mostly corresponded to the smooth muscle cells of the muscularis mucosae, and the arteriolar and venular smooth muscle cells. On the other hand, 1 week after the acetic acid treatment, the fluorescence of the smooth muscle cells of the muscularis mucosae disappeared and a large number of fluorescent interstitial cells, probably corresponding to myofibroblasts, appeared in the regenerated mucosal layer. Three weeks after the application, severely thickened fluorescent muscularis mucosae were formed and the fluorescence of the interstitial cells was rather decreased.

Fluorescent histochemical study on the localization of myofibroblasts in the healing of acetic acid-induced gastric ulcers in the rat

The changes in the localization of FITC-phalloidin-positive smooth muscle cells and interstitial cells were studied in control and acetic acid-treated rat fundic mucosae. In the control rats, the FITC-phalloidin-positive cells mostly corresponded to smooth muscle cells of the muscularis mucosae, and arteriolar and venular smooth muscle cells. On the other hand, the fluorescence of the smooth muscle cells of the muscularis mucosae disappeared and a large number of fluorescent interstitial cells appeared in the regenerated mucosal layer in rats one week after the acetic acid-treatment, while three weeks after the application, severely thickened fluorescent muscularis mucosae were formed.

Involvement of autonomic nervous system in gastric mucosal defense mechanism

This article describes the histochemical, immunohistochemical, radioautographic, and ultrastructural localizations of aminergic and peptidergic nerves, neurotransmitter receptors, and their binding sites in the stomach wall. Cholinergic and vasoactive intestinal polypeptide (VIP)-ergic nerve fibers are distributed along the gastric microvasculature, within the myenteric and submucosal plexuses, and in the muscularis mucosae and circular muscle layer. In the mucosa, both nerve fibers evenly extend along the capillaries in association with the epithelial cells up to the mucosal surface. In particular, cholinergic nerves are proved to doubly innervate the mucosal capillaries and nonmuscular venules as well as the parietal cells. Adrenergic and neuropeptide Y (NPY)-containing nerves are distributed primarily along the arterioles of the gastric microvasculature, within the myenteric plexuses, and in the circular muscle layer. These nerve fibers extend up to the basal portion of the mucosa in close association with small arterioles, capillaries, and epithelial cells. Some of the adrenergic nerve axons are coexistent with the cholinergic nerve axons within the Schwann cell. Histamine H1 receptors are widely located on the walls of arterioles, capillaries and venules, while H2 receptors are evident not only on the parietal cells but also on the walls of the collecting venules and surrounding capillaries in the mucosa. Dopamine D1 receptors are predominantly located on the smooth muscle cells of the arterioles near the muscularis mucosae, while D2 receptors are present on the walls of postcapillary venules and collecting venules. Functional coordination of both intramural peptidergic nerves as intrinsic origin and aminergic nerves as extrinsic origin is considered to be essential for maintaining the gastric mucosal defense mechanism against a variety of aggressive factors.