Global warming intensifies the interference competition by a poleward-expanding invader on a native dragonfly species

Rapid climate warming has boosted biological invasions and the distribution or expansion polewards of many species: this can cause serious impacts on local ecosystems within the invaded areas. Subsequently, native species may be exposed to threats of both interspecific competition with invaders and temperature rises. However, effects of warming on interspecific interactions, especially competition between invader and native species remains unclear. To better understand the combined threats of biological invasions and warming, the effect of temperature on competitive interactions between two dragonfly species, the expanding Trithemis aurora from Southeast Asia and the Japanese native Orthetrum albistylum speciosum were assessed based on their foraging capacity. Although the stand-alone effect of temperature on foraging intake of the native dragonfly was not apparent, its intake significantly decreased with increasing temperatures when the invader T. aurora was present. Such reductions in foraging might lead to displacement of the native species through competition for food resources. This suggests that impacts of invader species against native species are expected to be more severe when interspecific competition is exacerbated by temperature rises.

Acute toxicity data of common agricultural insecticides to Japanese wild bees

Although numerous ecotoxicological assessments of European honeybee (Apis mellifera L.) have been performed, Japanese wild bees are less well studied in this regard. To address this knowledge gap, we assessed the mortality and acute toxicity (LD₅₀) of 3 common agricultural insecticides (clothianidin, fipronil, and diazinon) on as many as 6 species of Japanese wild bees (Andrena prostomias Perez, Apis cerana japonica Radoszkowski, Bombus deuteronymus Perez, Bombus honshuensis Tkalcu, Bombus hypocrita Perez, and Eucera spp.; all or any of them). The datasets were obtained via standard acute toxicity testing, with assessment of mortality at 24 and 48 h after exposure to the insecticides. These data provide important information regarding the effects of insecticides on Japanese wild bees and their conservation.

Acute toxicity of fipronil to an invasive ant, Lepisiota frauenfeldi

Slow-acting fipronil is one of the best components for controlling invasive ants. However, its efficacy against invasive Lepisiota frauenfeldi, which recently invaded Japan, remains unclear. Here, its acute toxicity to Le. frauenfeldi was assessed, and its lethal concentrations were compared with those against other invasive ants (Linepithema humile and Solenopsis invicta). The LC₁₀ and LC₅₀ values of fipronil for Le. frauenfeldi were significantly lower than the previously reported values for Li. humile and/or S. invicta, and its LC₉₀ value against Le. frauenfeldi was in the same range as that required for Li. humile extermination. Additionally, Le. frauenfeldi can be more sensitive to fipronil than non-target arthropods. Therefore, recent fipronil-based Li. humile and S. invicta eradication/control programs may be effective against Le. frauenfeldi as well. Moreover, applying fipronil at dosages appropriate for Le. frauenfeldi would lead to effective Le. frauenfeldi extermination/control with low damage to other native species/ants.

Dry-Heat Tolerance of Egg Sacs of Invasive Latrodectus Spiders (Araneae: Theridiidae) in Japan: Implications for Efficient Control/Extermination

Strategic responses to invasive Latrodectus widow spiders are a global challenge due to the risks they pose to health and ecosystems. Chemical strategies involving the use of pyrethroids are effective against adult spiders, but as their populations rebound, chemical control becomes costly and unsustainable for eradication. A major obstacle is the inefficacy of insecticides against eggs, which are covered by a protective silk egg sac. Eradication of invasive spiders must focus on destroying progeny. Here, the responses of eggs in egg sacs of two invasive Latrodectus spiders in Japan (Latrodectus hasseltii (Thorell) and Latrodectus geometricus (C.L. Koch)) to short-term dry-heat exposure were examined. To test whether the dry-heat tolerance of the egg sacs of both spider species differed, lethal temperature (LT) was determined based on the hatching rate of eggs from egg sacs subjected to a range of temperatures. Hatching in both species failed completely when the egg sacs were exposed to temperatures of 55°C and above for 10 min, but the LT to reduce hatching by 90% (LT90) differed significantly between L. hasseltii (50. 9°C) and L. geometricus (52. 8°C). Our study highlights the efficacy of dry heat in suppressing hatching and thus shows the possibility for effective extermination of these noxious invasive pests. Further exploration and investigation of the effects of humidity and heat exposure time on egg sacs under field conditions are needed to guide Latrodectus spider control strategies.

Starting Neurohormonal Antagonists in Patients with Acute Heart Failure with Mid-Range and Preserved Ejection Fraction

Background

The clinical benefits of neurohormonal antagonist in patients with heart failure (HF) with mid-range and preserved ejection fraction (HFmrEF and HFpEF) were uncertain. This study aimed to evaluate the prognostic effect of starting angiotensin-converting enzyme inhibitors (ACE-I) / angiotensin II receptor blockers (ARB) and β-blocker during HF hospitalization in these patients.

Methods

We analyzed 858 consecutive patients with HFmrEF (EF:40–49%) or HFpEF (EF≥50%), who were hospitalized for acute decompensated HF, were discharged alive, and were not taking ACE-I/ARB or β-blockers at admission. The study population was classified into four groups according to the status of prescription of ACE-I/ARB and β-blocker at discharge: no neurohormonal antagonist (N=342, 39.9%), ACE-I/ARB only (N=128, 14.9%), β-blocker only (N=189, 22.0%), and both ACE-I/ARB and β-blocker (N=199, 23.2%) groups. The primary outcome measure was a composite of all-cause death or HF hospitalization.

Results

The cumulative 1-year incidence of the primary outcome measure was 41.2% in the no neurohormonal antagonist group, 34.0% in the ACE-I/ARB only group, 28.6% in the β-blocker only group, and 16.4% in the both ACE-I/ARB and β-blocker group (P<0.001). Compared with the no neurohormonal antagonist group, the both ACE-I/ARB and β-blocker group were associated with a significantly lower risk for a composite of all-cause death or HF hospitalization (HR: 0.59, 95% CI: 0.38–0.91, P=0.02).

Conclusions

In hospitalized patients with HFmrEF and HFpEF, starting both ACE-I/ARB and β-blocker was associated with a reduced risk of a composite of all-cause death or HF hospitalization compared with not starting ACE-I/ARB or β-blocker.

Funding Acknowledgement

Type of funding sources: None.

Intraspecific differences in the invasion success of the Argentine ant Linepithema humile Mayr are associated with diet breadth

The Argentine ant, Linepithema humile Mayr, has spread to almost all continents. In each introduced region, L. humile often forms a single large colony (supercolony), the members of which share the haplotype "LH1", despite the presence of other supercolonies with different genetic structures. However, the mechanisms underlying the successful invasion of LH1 ants are unclear. Here, we examined whether diet breadth differs between more successful (LH1) and less successful (LH2, LH3, LH4) L. humile supercolonies in Japan to better understand the processes responsible for invasion success. The standard ellipse areas (SEAs) of δ13C and δ15N and their ranges (CR and NR) were used as diet breadth indices. The SEAs of LH1 were much larger than those of the less successful supercolonies despite no differences in the baseline SEAs of arthropods within the supercolony habitats, indicating that the invasion success of a supercolony is associated with its diet breadth. Furthermore, LH1 had a broader CR than the other supercolonies, suggesting that which might be derived from superior resource exploitation ability. Our study highlights the importance of focusing on intraspecific differences in diet breadth among supercolonies when assessing organisms that can potentially invade and become dominant in new habitats.

A decrease in tricuspid regurgitation pressure gradient during follow-up in patients with heart failure

Objective

This study aimed to investigate the prognostic impact of the decrease in tricuspid regurgitation pressure gradient (TRPG) at 6-month follow-up in patients after discharge with heart failure (HF).

Background

No previous study has reported the association between TRPG decrease during follow-up and clinical outcomes in HF.

Methods

Among 748 patients with 6-months follow-up echocardiography after discharge from the acute decompensated heart failure in 19 centers in Japan, we analyzed 721 patients with available TRPG data and divided into two groups: the decrease in TRPG group (N=179) and no decrease in TRPG group (N=542). We defined the decrease in TRPG as >10mmHg decrease compared in the initial hospitalization. The primary outcome measure was a composite of all cause deaths and hospitalization due to HF.

Results

The patients in the decrease in TRPG group had a lower prevalence of hypertension, dyslipidemia, atrial fibrillation, and a reduced EF, higher levels of blood albumin and lower levels of sodium than those in no decrease in TRPG group. The median follow-up duration after the follow up echocardiography was 302 (inter quartile range: 206–490), with a 90.9% follow up rate at 6-month. The cumulative 6-month incidence of the primary outcome measure was significantly lower in the decrease in TRPG group than in no decrease in TRPG group (12.2% vs. 18.9%, P=0.0011). After adjusting confounders, the excess risk of the decrease in TRPG relative to no decrease in TRPG for the primary outcome measure remained significant (HR: 0.60, 95% CI 0.34–0.99). There were no significant interactions between the subgroup factors and the effect of the decrease in TRPG for primary outcomes.

Conclusions

HF patients with the decrease in TRPG at 6-month after discharge had a lower risk of clinical outcome than those without decrease in TRPG.

Funding Acknowledgement

Type of funding source: None

Host-Tree Selection by the Invasive Argentine Ant (Hymenoptera: Formicidae) in Relation to Honeydew-Producing Insects

The Argentine ant, Linepithema humile (Mayr; Hymenoptera: Formicidae), is one of the world's most hazardous invasive species, and thus its eradication from Japan is important. Physical and chemical controls can be expensive and cause strong adverse effects on local terrestrial ecosystems regardless of their high efficacy. Here, presence/absence of host-tree selection by Argentine ants was investigated to understand the ant-honeydew-producing insects interactions in order to develop new cultural controls compatible with biodiversity conservation. Abundance of Argentine ants and their tree utilization ratio was measured among dominant roadside trees (Cinnamomum camphora, Myrica rubra, Nerium indicum, Rhaphiolepis indica var. umbellata, Juniperus chinensis var. kaizuka) in two areas around Kobe, Japan. Almost all ants collected were Argentine ants suggesting that native ants would have been competitively excluded. Tree utilization of Argentine ants clearly differed among host trees. Abundance of both Argentine ants and honeydew-producing insects and tree utilization rate of the ants were significantly lower in especially C. camphora and J. chinensis. Few Argentine ants were observed trailing on C. camphora, J. Chinensis, and N. indicum, most probably due to low abundance of honeydew-producing insects on these trees with the toxic and repellent chemical components. On the other hand, high abundance of both Argentine ants and homopterans were found in M. rubra and especially R. indica. We suggest that reductions of R. indica and M. rubra would lead to a decrease in abundance of honeydew-producing insects, and thus effectively control populations of Argentine ants. At the same time, planting of C. camphora, J. Chinensis, and N. indicum may also play a role in restraint efficacy against invasion of the invasive ants.

Expression of tumour necrosis factor (TNF) ligand superfamily co-stimulatory molecules CD30L, CD27L, OX40L, and 4-1BBL in murine hearts with acute myocarditis caused by Coxsackievirus B3

Antigen-specific T-cells infiltrate the heart and play an important role in the myocardial damage involved in acute myocarditis and dilated cardiomyopathy. To investigate the roles of the co-stimulatory molecules CD30/CD30L, CD27/CD27L, OX40/OX40L, and 4-1BB/4-1BBL, which belong to the tumor necrosis factor (TNF) receptor/ligand superfamily, in the development of acute viral myocarditis, the expression of these molecules was first analysed in the hearts of mice with acute myocarditis induced by Coxsackievirus B3 (CVB3) in vivo. Secondly, the induction of these molecules was evaluated on cultured cardiac myocytes treated with interferon (IFN)-gamma and the interleukin (IL)-6 production by cultured cardiac myocytes was analysed by stimulation with monoclonal antibodies (MAbs) against these molecules in vitro. Thirdly, the effects of in vivo administration of anti-CD30L, anti-CD27L, anti-OX40L, or anti-4-1BBL MAb on the development of acute viral myocarditis were examined. CVB3-induced myocarditis resulted in the induction of CD30L and 4-1BBL on the surface of cardiac myocytes, confirmed by treatment with IFN-gamma in vitro. CD27L and OX40L were constitutively expressed on cardiac myocytes in vivo and in vitro. Anti-CD30L and anti-4-1BBL MAbs stimulated IL-6 production by cardiac myocytes in vitro. Furthermore, in vivo anti-4-1BBL MAb treatment significantly decreased the myocardial inflammation, whereas the other MAbs did not. These findings suggest that TNF ligand superfamily co-stimulatory molecules, especially 4-1BBL, play an important role in the development of acute viral myocarditis and raise the possibility that immunotherapy with anti-4-1BBL MAb may be of benefit in acute viral myocarditis.

Clinicopathological report of retinitis pigmentosa with vitamin E deficiency caused by mutation of the alpha-tocopherol transfer protein gene

PURPOSE

To discuss the clinicopathological findings in a patient with retinitis pigmentosa (RP) accompanied by a vitamin E deficiency caused by an H101Q mutation in the alpha-tocopherol transfer protein (alpha-TTP) gene.

CASE

The clinical course of this patient was followed by conventional ophthalmological examinations over a 3-year period. After the patient died from pancreatic cancer, the eyes were obtained, and examined by light and electron microscopy.

OBSERVATIONS

The patient complained of night blindness subsequent to adult-onset ataxia, although the ataxia was very mild. His visual acuity was 0.6 OU, and ophthalmoscopy revealed RP sine pigmento. Ring scotomas were detected, and the electroretinography, electro-oculography, and dark-adaptation were altered. Fluorescein angiography showed granular hyperfluorescence around the macula. No progression of the visual and neurological symptoms was observed during the 10 years he was taking oral vitamin E. Histopathological examination revealed the loss of the outer and inner segments of the photoreceptors in the area corresponding to the ring scotoma, as well as a disorganization and shortening of the outer segments in the peripheral retina.

CONCLUSIONS

We conclude that the clinical and pathological findings in the eyes of this patient having RP with vitamin E deficiency caused by an H101Q mutation are similar to those of common autosomal recessive RP. However, special attention is required in making a diagnosis of RP with vitamin E deficiency because RP with vitamin E deficiency is medically treatable. The mild Friedreich-type ataxia accompanying the RP may be helpful in identifying this disease.

Change in spin state and enhancement of redox reactivity of photoexcited states of aromatic carbonyl compounds by complexation with metal ion salts acting as Lewis acids. Lewis acid-catalyzed photoaddition of benzyltrimethylsilane and tetramethyltin via photoinduced electron transfer

The lowest excited state of aromatic carbonyl compounds (naphthaldehydes, acetonaphthones, and 10-methylacridone) is changed from the n,pi triplet to the pi,pi singlet which becomes lower in energy than the n,pi triplet by the complexation with metal ions such as Mg(ClO(4))(2) and Sc(OTf)(3) (OTf = triflate), which act as Lewis acids. Remarkable positive shifts of the one-electron reduction potentials of the singlet excited states of the Lewis acid-carbonyl complexes (e.g., 1.3 V for the 1-naphthaldehyde-Sc(OTf)(3) complex) as compared to those of the triplet excited states of uncomplexed carbonyl compounds result in a significant increase in the redox reactivity of the Lewis acid complexes vs uncomplexed carbonyl compounds in the photoinduced electron-transfer reactions. Such enhancement of the redox reactivity of the Lewis acid complexes leads to the efficient C-C bond formation between benzyltrimethylsilane and aromatic carbonyl compounds via the Lewis-acid-promoted photoinduced electron transfer. The quantum yield determinations, the fluorescence quenching, and direct detection of the reaction intermediates by means of laser flash photolysis experiments indicate that the Lewis acid-catalyzed photoaddition reactions proceed via photoinduced electron transfer from benzyltrimethylsilane to the singlet excited states of Lewis acid-carbonyl complexes.

Effect of long-term treatment with vanadate in drinking water on KK mice with genetic non-insulin-dependent diabetes mellitus

The glucose-lowering effect of vanadate, ammonium metavanadate (AMV), on diabetic KK mice was examined. Five-week-old male KK mice were administrated with a solution of AMV via drinking water at concentrations of vanadium (V) with 0.1, 1.0, 10 and 100 microg/mL for a period of 10 wk, respectively. Body weight, consumption of food and water, and blood glucose levels was measured every week for 10 wk. The results showed that food consumption and body weight in the experimental groups were similar to those in the control group. A statistically significant decrease of drinking water consumption and blood glucose levels in the group treated with 100 microg V/mL was observed. The glucose tolerance in the vanadate-treated mice with 10 and 100 microg V/mL was remarkably improved compared with the control group. Biochemical analyses at the end of experiments demonstrated that a distinct tendency for the glucose and hemoglobin A1c (HbA1c) levels to decrease with vanadate treatment in the blood was also observed. The glutamic pyruvic transaminase, glutamic oxaloacetate transaminase, blood urea nitrogen, triglyceride, high-density lipoprotein, and total cholesterol levels in plasma were lower in the higher vanadium groups than those in the control group. These results indicate that vanadium effectively produced the glucose-lowering effect at a higher dose than that at a low dose of vanadium in drinking water, without any overt signs of toxicity.

Blue light-induced apoptosis in cultured retinal pigment epithelium cells of the rat

BACKGROUND

We previously demonstrated that phagosome-free retinal pigment epithelium (RPE) cells in culture can be damaged directly by blue light (wavelength 440+/-10 nm) as observed by electron microscope. A low intensity (1.0 mW/cm2) of light induced only swelling of mitochondria, while a high intensity (4.0 mW/cm2) induced necrosis in the RPE. The aim of the present study was to investigate what intensity of blue light could induce apoptosis in cultured phagosome-free RPE.

METHODS

Primary cultured RPE cells, harvested from Long-Evans rats, that contained no phagosomes were exposed to a cool blue light (wavelength 440+/-10 nm). After exposure, transmission electron microscopy (TEM) and TdT-mediated dUTP nick-end labeling (TUNEL) staining were used to detect apoptosis in the RPE cells. To assess the relationship of oxidation to apoptosis by blue light, we added N-acetylcysteine (NAC) as a free radical scavenger and investigated its inhibitory effect on apoptosis.

RESULTS

In RPE cells exposed to blue light of 2.7 mW/cm2 for 24 h, apoptotic bodies were found by TEM. In RPE cells exposed to blue light of 2.0 mW/cm2 for 60 h, apoptotic bodies, nuclear condensation and nuclear segmentation were observed by TEM and some RPE cells showed positive TUNEL staining. When 30 mM of NAC was added, TUNEL staining was negative.

CONCLUSION

Our findings demonstrate that apoptotic cell death is induced by blue light exposure in cultured RPE cells in vitro. The findings of our previous experiments and those of the present study suggest that a higher intensity of blue light could induce necrosis, and moderately intense blue light could induce non-necrotic cell death or apoptosis, in RPE cells. Furthermore, it is suggested that blue light caused cell death by a free-radical-associated mechanism.

Clinical course of newly developed or progressive patchy chorioretinal atrophy in pathological myopia

Regional chorioretinal atrophy in the posterior fundus (patchy chorioretinal atrophy) in pathological myopia impairs vision severely when it covers the macula. The aim of this study was to assess the course of development and progression of patchy chorioretinal atrophy in pathological myopia. The location and progression of patchy chorioretinal atrophy that was either newly developed or had progressed during the follow-up period (mean 5.25 years) were analyzed. A total of 41 lesions of patchy atrophy were newly developed in 30 eyes of 25 patients. These lesions were more likely to occur in marginal regions of a posterior staphyloma but frequency per unit area was highest in the macula. There were 138 lesions of patchy chorioretinal atrophy that progressed in 75 eyes of 53 patients. Sixty percent of the lesions of patchy chorioretinal atrophy in marginal regions of a posterior staphyloma spread toward the center. Seventy percent of the lesions of patchy chorioretinal atrophy in the macula spread in all directions. Fluorescein angiography of newly developed patchy chorioretinal atrophy showed hyperfluorescence in 50% and hypofluorescence in 27%. Fluorescein angiography of progressive lesions of patchy chorioretinal atrophy showed hypofluorescence in 69%. Fluorescein angiography of some progressive areas of patchy chorioretinal atrophy, which showed a change from hyperfluorescence to hypofluorescence within several years, suggested that damage to the retinal pigment epithelium preceded the progression of the patchy chorioretinal atrophy. In conclusion, the patchy chorioretinal atrophy is most likely to occur in the macula and to enlarge in all directions. And it is suggested that the patchy chorioretinal atrophy which shows hyperfluorescence by fluorescein angiography should be kept under observation because our data suggest that this finding indicates progression in the future.

Restricted usage of T-cell receptor Vgamma-Vdelta genes and expression of costimulatory molecules in Takayasu's arteritis

To further investigate the immunological mechanisms involved in Takayasu's arteritis, we analyzed the T-cell receptor (TCR) Vgamma and Vdelta gene usage by infiltrating gammadelta T-cells and the expression of costimulatory molecules B7-1, B7-2, CD40, CD27 ligand (CD27L), CD30L, OX40L in the arterial tissue of a patient with Takayasu's arteritis. We found that the repertoires of TCR Vgamma as well as Vdelta gene transcripts of the infiltrating cells were restricted as compared with those of peripheral blood lymphocytes from a patient with Takayasu's arteritis. This strongly suggests that gammadelta T-cells as well as alphabeta T-cells, as we previously reported, were specifically involved in the pathogenesis of Takayasu's arteritis. We also found that B7-1, B7-2, CD40, CD27L, CD30L, and OX40L were expressed in the arterial tissue, suggesting the roles for these costimulatory molecules in T-cell-mediated vascular injury in Takayasu's arteritis. Our findings strongly support the involvement of T-cell-mediated immunological mechanisms in the pathogenesis of Takayasu's arteritis.

Retinoic acid increases in the retina of the chick with form deprivation myopia

We previously reported that expression of retinoic acid receptor beta increases in the sclera of the 2-week-old chick with form deprivation myopia (FDM) and that all-trans-retinoic acid (t-RA) influences proliferation and differentiation of scleral cells. The purpose of this study was to quantify t-RA in the retina of the chick with FDM and to investigate the role of t-RA in FDM in the chick. FDM was induced in 2-day-old chicks by placement of a translucent plastic goggle over one eye, with the contralateral eye used as a control. After 5 days, the chicks were sacrificed. t-RA was extracted from neural retina and served for high-performance liquid chromatography analysis. 3H-t-RA was used for normalization. Pieces of the retinae from 5 eyes served as one sample. As a result, t-RA was 09.60 +/- 0.86 ng/eye (0.387 +/- 0.056 ng/mg protein) in the myopic retina was significantly higher than that in the control (p < 0.05, n = 7). These results demonstrate that t-RA increases in the retina within 5 days after visual deprivation. This finding suggests that t-RA may play a role in the metabolic changes in FDM.

Left cervical aortic arch with aortic coarctation and saccular aneurysm

Cervical aortic arch is a very rare malformation and is occasionally accompanied by other cardiovascular anomalies. A 48-year-old male patient had a left cervical aortic arch with aortic coarctation and saccular aneurysm distal to the coarcted segment. The major clinical manifestations were upper body hypertension with a 50-mmHg discrepancy between the upper and lower limbs and a loud continuous murmur in the upper chest and back. Magnetic resonance angiography successfully depicted the anomalous aorta, and the aortic coarctation and aneurysm were surgically resected and the thoracic aorta was reconstructed. The discrepancy in blood pressure diminished after the operation, but antihypertensive medication was continued to satisfactorily control the hypertension.

Takayasu arteritis: insights into immunopathology

Takayasu arteritis is an acute and sometimes chronic form of vasculitis involving the aorta, its main branches and pulmonary arteries. Although its etiology is still unknown, immunopathologic analyses revealed that the infiltrating cells mainly consisted of gammadelta T-cells as well as alphabeta T-cells and NK cells. The infiltrating gammadelta T-cells, cytotoxic T-lymphocytes (CTLs), and natural killer (NK) cells directly injured the vascular cells by releasing a cytolytic factor, perforin. Expression of heat-shock protein (HSP)-65 as well as human leukocyte antigen (HLA) class I and II was enhanced in Takayasu arteritis lesions, supporting the pathogenic role of gammadelta T-cells and alphabeta T-cells. T-cell receptor (TCR) alphabeta gene usage by the infiltrating cells was restricted, strongly suggesting that a specific antigen was targeted. TCR gammadelta gene usage by the infiltrating cells was also restricted. Furthermore, it has been reported that a strong association with a specific haplotype of major histocompatibility complex (MHC) class I chain-related (MIC), MICA gene with Takayasu arteritis, suggesting that the HLA-linked gene susceptible to the disease is mapped near the MICA gene. This also supports a pathogenic role of gammadelta T-cells in Takayasu arteritis because gammadelta T-cells were shown to recognize MICA molecule, which can be stress-induced. These findings suggest that unknown stress, such as infection, may trigger the autoimmune process of inflammation involved in Takayasu arteritis.

Disturbance of electrolyte balance in vitreous of chicks with form-deprivation myopia

PURPOSE

To investigate the changes in the electrolyte and protein concentrations in the vitreous of 3-week-old chicks with form-deprivation myopia (FDM).

METHODS

FDM was induced in 2-day-old male white leghorn chicks by covering the left eye with a translucent plastic goggle and leaving the right eye uncovered to serve as control. After 19 days the animals were euthanized, and the axial dimensions of the eyes were measured with a caliper in an unfixed condition. The liquid vitreous and aqueous humor were removed by paracentesis, and blood was collected from the jugular vein. Sodium, potassium, and chloride concentrations were determined using ion-selective electrodes. Calcium and phosphate concentrations were determined by colorimetric assays using orthocresol phthalein complexone and bacterial xanthine oxidase, respectively.

RESULTS

The concentrations of potassium and phosphate were decreased, whereas chloride concentration was increased in the vitreous of the FDM eyes (P < .01). Sodium and calcium concentrations were similar to those in the control eyes. No significant changes in the concentration of electrolytes were observed in the aqueous humor. No significant differences were found in the protein concentrations in the liquid vitreous, gel vitreous, and aqueous humor.

CONCLUSIONS

Form-deprivation induced a significant increase of the volume of the liquid vitreous in the eye of the FDM chick. The increased liquid vitreous of the myopic eye was accompanied by an alteration of the electrolyte balance, by a mechanism that has not yet been clarified.

Serum levels of vascular endothelial growth factor and transforming growth factor-beta1 in patients with atrial fibrillation undergoing defibrillation therapy

We have previously reported that pulsatile mechanical stretch in vitro induced rapid secretion of vascular endothelial growth factor (VEGF) by cultured cardiac myocytes and that the stretch-induced secretion of VEGF was mainly mediated by secretion of transforming growth factor (TGF)-beta1 by cardiac myocytes in an autocrine fashion. To investigate whether tachycardia-induced mechanical overload increases serum levels of VEGF and TGF-beta1, we investigated the serum levels of VEGF and TGF-beta1 in patients with atrial fibrillation undergoing defibrillation therapy. The serum VEGF level before defibrillation was significantly increased in 13 out of 20 patients (89.48 +/- 16.09 pg/ml [mean +/- SE]). After defibrillation, the serum VEGF level in these 13 patients significantly (p = 0.019) decreased (65.04 +/- 16.61 pg/ml [mean +/- SE]), although it increased slightly in one patient. The serum TGF-beta1 level before defibrillation therapy (13.01 +/- 1.97 pg/ml [mean +/- SE]) in these 12 patients also decreased after defibrillation therapy (11.47 +/- 2.06 pg/ml [mean +/- SE]). The changes in serum VEGF level significantly correlated with those in the serum TGF-beta1 level in these 12 patients (r = 0.73, p < 0.05, n = 12). Our data suggest that tachyarrhythmia-induced mechanical overload can increase the serum VEGF level, which can be a useful clinical marker for relative myocardial oxygen shortage in such patients.

Induction of vascular endothelial growth factor after application of mechanical stress to retinal pigment epithelium of the rat in vitro

PURPOSE

To investigate the response to mechanical stress of vascular endothelial growth factor (VEGF) production by cultured retinal pigment epithelial (RPE) cells.

METHODS

A pulsatile stretch device was used in vitro. RPE cells of the second passage were seeded onto flexible-bottomed culture plates; then, at subconfluent culture, the plates were subjected to pulsatile stretch. Culture plates prepared in the same way but not subjected to stretch were used as controls. After stretching for 1 hour or 24 hours, conditioned medium for measurement of VEGF production by RPE cells was collected using a mouse VEGF immunoassay. To study the expression of VEGF in RPE cells, passaged-cultured RPE cells were exposed to pulsatile stretch for 0, 1, 3, or 14 hours. Total cytoplasmic RNA was then prepared from the RPE cells. Northern blot analysis was performed for VEGF, with G3PDH used as an internal control.

RESULTS

The expression and secretion of VEGF in RPE cells were increased by pulsatile stretching.

CONCLUSIONS

Results indicate that stretching of the RPE could result in increased production of VEGF, with associated risk for neovascularization and changes in the blood-retinal barrier.

Active oxygen species generation and cellular damage by additives of parenteral preparations: selenium and sulfhydryl compounds

We investigated the relationship between active oxygen species (AOS) generation and cultured vascular endothelial cellular damage caused by simultaneous exposure to selenium compounds and sulfhydryl compounds such as cysteine (Cys) or reduced glutathione (GSH). Selenium compounds, selenite, selenate or selenomethionine (SeMet), are added to total parenteral nutrition (TPN) and intravenously administered. We confirmed by luminol dependent chemiluminescence, an indicator of AOS generation, that selenite generates AOS in the presence of clinical concentrations of sulfhydryl compounds, 0.5 mM Cys or 0.5 mM GSH, and that the amount of AOS generated reaches the maximum when their mole ratio is 1:50. However, AOS generation was not observed after simultaneous administration of various concentrations of selenate or SeMet with sulfhydryl compounds. Moreover, simultaneous exposure to 10 microM selenite and sulfhydryl compounds was found to result in significant increases in the [3H]-adenine and lactate dehydrogenase (LDH) release rates from cells, a significant decrease in the amount of cellular protein, and enhancement of cellular damage as compared with after exposure to selenite alone. However, simultaneous exposure to 10 microM selenate or 10 microM SeMet together with sulfhydryl compounds did not induce cellular damage. These findings revealed that selenite generates AOS and causes cellular damage in the presence of sulfhydryl compounds. Accordingly, it seems better to choose selenate or SeMet instead of selenite when a selenium compound is to be added to TPN.

Hypoxia induces activation and subcellular translocation of focal adhesion kinase (p125(FAK)) in cultured rat cardiac myocytes

We previously reported that hypoxia caused rapid activation of RAS/mitogen-activated protein kinase (MAPK) pathway, two other stress-activated MAPK family members, stress-activated protein kinase (SAPK) and p38MAPK, and Src family tyrosine kinases, p60(c-src) and p59(c-fyn) in cultured rat cardiac myocytes. In this study, to elucidate how hypoxia affects adhesive interaction between cardiac myocytes and extracellular matrix (ECM), we investigated the molecular mechanism of the activation of focal adhesion-associated tyrosine kinases p125(FAK) and paxillin. Here, we show that hypoxia induced tyrosine phosphorylation of p125(FAK) and paxillin and that hypoxia-induced activation of p125(FAK) was accompanied by its increased association with adapter proteins Shc and GRB2, and non-receptor type tyrosine kinase p60(c-src). Furthermore, hypoxia caused subcellular translocation of p125(FAK) from perinuclear sites to the focal adhesions. These results strongly suggest that p125(FAK) is one of the most important components in hypoxia-induced intracellular signaling in cardiac myocytes and may play a pivotal role in adhesive interaction between cardiac myocytes and ECM.

Expression of tumour necrosis factor (TNF) receptor/ligand superfamily co-stimulatory molecules CD40, CD30L, CD27L, and OX40L in murine hearts with chronic ongoing myocarditis caused by coxsackie virus B3

T-cell-mediated myocardial damage has been shown to be involved in acute myocarditis and dilated cardiomyopathy. It is necessary for T-cells to receive a co-stimulatory signal as well as the main signal through the T-cell receptor for antigen-specific T-cell activation to occur. To investigate the roles of the co-stimulatory molecules CD40/CD40L, CD30/CD30L, CD27/CD27L, and OX40/OX40L, which belong to the tumour necrosis factor (TNF) receptor/ligand superfamily, in the development of chronic ongoing myocarditis, the expression of CD40, CD30L, CD27L, and OX40L was analysed in the hearts of A/J mice with myocarditis induced by Coxsackie virus B3 (CVB3). The expression of CD40L, CD30, CD27, and OX40 was also examined on the infiltrating cells. Furthermore, the induction of CD40, CD30L, CD27L, and OX40L was evaluated on cultured cardiac myocytes treated with interferon (IFN)-gamma. CVB3-induced myocarditis resulted in the induction of CD40 and CD30L on the surface of cardiac myocytes. Induction of CD40 and CD30L on cardiac myocytes was confirmed by treatment with IFN-gamma in vitro. CD27L and OX40L were expressed on cardiac myocytes in vivo and in vitro. The expression of CD27L and OX40L on cardiac myocytes was increased, at least partly, by CVB3-induced myocarditis in vivo. Many infiltrating cells expressed CD27 and OX40, whereas much smaller numbers expressed CD40L and CD30. The induction of these molecules, especially CD40 and CD30L, on cardiac myocytes strongly suggests that cardiac myocytes may co-stimulate T-cells and induce cytokine production by T-cells and humoral immune responses. This may play an important role in the pathogenesis of the resulting myocardial damage.

Vascular endothelial growth factor induces activation and subcellular translocation of focal adhesion kinase (p125FAK) in cultured rat cardiac myocytes

Vascular endothelial growth factor (VEGF) has been proposed to be among the candidate factors with the most potential to play a role in ischemia-induced collateral vessel formation. Recently, we found that VEGF activated the mitogen-activated protein kinase cascade in cultured rat cardiac myocytes. To elucidate how VEGF affects adhesive interaction of cardiac myocytes with the extracellular matrix (ECM), one of the important cell functions, we investigated the molecular mechanism of activation of focal adhesion-related proteins, especially focal adhesion kinase (p125(FAK)), in cultured rat cardiac myocytes. We found that the 2 VEGF receptors, KDR/Flk-1 and Flt-1, were expressed in cardiac myocytes and that KDR/Flk-1 was significantly tyrosine phosphorylated on VEGF stimulation. VEGF induced tyrosine phosphorylation and activation of p125(FAK) as well as tyrosine phosphorylation of paxillin; this was accompanied by subcellular translocation of p125(FAK) from perinuclear sites to the focal adhesions. This VEGF-induced activation of p125(FAK) was inhibited partially by the tyrosine kinase inhibitors genistein and tyrphostin. Activation of p125(FAK) was accompanied by its increased association with adapter proteins GRB2, Shc, and nonreceptor type tyrosine kinase p60(c-src). Furthermore, we confirmed that VEGF induced a significant increase in adhesive interaction between cardiac myocytes and ECM using an electric cell-substrate impedance sensor. These results strongly suggest that p125(FAK) is one of the most important components in VEGF-induced signaling in cardiac myocytes, playing a critical role in adhesive interaction between cardiac myocytes and ECM.

Pulsatile stretch activates mitogen-activated protein kinase (MAPK) family members and focal adhesion kinase (p125(FAK)) in cultured rat cardiac myocytes

Recently, we demonstrated that pulsatile mechanical stretch induced rapid secretion of vascular endothelial growth factor (VEGF) by cultured rat cardiac myocytes in vitro. To investigate whether pulsatile stretch activates intracellular signaling in cardiac myocytes, we examined the activation of mitogen-activated protein kinase (MAPK) family members and focal adhesion kinase (p125(FAK)) in cultured rat cardiac myocytes. We found that pulsatile stretch rapidly phosphorylated p44/p42 MAPKs (extracellular signal-regulated protein kinase [ERK] 1/2), stress-activated protein kinase (SAPK), p38MAPK, and p125(FAK). The stretch-induced activation of ERKs was at least partly mediated by VEGF, which was shown to be induced by transforming growth factor (TGF)-beta, and was also partly dependent on tyrosine kinases as well as protein kinase C (PKC). These data provide the direct evidence that pulsatile stretch can activate intracellular signaling in cardiac myocytes and that this was at least partly mediated by VEGF, which may play a role in cardiac adaptation to mechanical overload.

Effects of in vivo administration of anti-B7-1/B7-2 monoclonal antibodies on the survival of mice with chronic ongoing myocarditis caused by Coxsackievirus B3

In acute myocarditis and dilated cardiomyopathy, it has previously been reported that antigen-specific T-cells infiltrate the heart and play an important role in the myocardial damage involved. For antigen-specific T-cell activation to occur, it is necessary for the T-cell to receive co-stimulatory signals provided by co-stimulatory molecules expressed on the antigen-presenting cell (APC), as well as the main signal provided by binding of the T-cell receptor (TCR) to the antigen. To investigate the roles for the co-stimulatory molecules B7-1 and B7-2 in the development of chronic ongoing viral myocarditis, firstly the expression of B7-1/B7-2 was analysed in the hearts of A/J mice with myocarditis induced by Coxsackievirus B3 (CVB3). Secondly the induction of B7-1/B7-2 on cultured cardiac myocytes treated with interferon (IFN)-gamma was evaluated. Thirdly the effects of the in vivo administration of anti-B7-1/B7-2 monoclonal antibodies (MAbs) on the survival of mice with viral myocarditis were examined. CVB3-induced myocarditis resulted in enhanced expression of B7-1/B7-2 on cardiac myocytes. The expression of B7-1/B7-2 on cardiac myocytes could be induced by IFN-gamma in vitro. In vivo anti-B7-1 MAb treatment significantly prolonged the survival of mice with myocarditis, whereas anti-B7-2 MAb treatment abrogated the protective effect of anti-B7-1. These findings indicate that distinct roles for B7-1 and B7-2 antigens are involved in the development of viral myocarditis and raise the possibility of immunotherapy with anti-B7-1 MAb to prevent T-cell-mediated cardiac myocyte injury and to improve the prognosis of viral myocarditis.

Processes of blue light-induced damage to retinal pigment epithelial cells lacking phagosomes

PURPOSE

To experimentally clarify the processes of the changes induced by blue light directly on the retinal pigment epithelium (RPE) before the formation of phagosomes or the accumulation of lipofuscin.

METHODS

We developed a new experimental method in which primary cultured cells of very young pigmented rats were exposed to several intensities and durations of blue light (wavelength = 440+/-10 nm).

RESULTS

At 1.0 mW/cm2, the damage was limited to mitochondria. At 2.0 mW/cm2, the cytoplasm exhibited large whorls of membrane or whorled inclusions, which were consistent with autophagic vacuoles. At 4.0 mW/cm2, the RPE cells showed lysis of the cytoplasm and a nucleus that was consistent with necrosis.

CONCLUSIONS

Our results suggested that damage induced by blue light to cultured RPE cells may originate in the mitochondria and end in necrosis. The type of cell death induced in the RPE by blue light seems to be determined mainly by the intensity of the light, but is also related to the duration of exposure.

Reduced sensitivity of HeLa cells to cis-platinum by simultaneous overexpression of copper, zinc-superoxide dismutase and catalase

The overexpression of catalase or Cu,Zn-superoxide dismutase (Cu,Zn-SOD) did not affect the sensitivity of HeLa cells to cis-platinum. However, the cytotoxicity of cis-platinum was depressed significantly by the simultaneous overexpression of catalase and Cu,Zn-SOD. We concluded that cis-platinum accelerated the generation of superoxide anion in the cells, and the superoxide anion produced was converted into H2O by the cooperative roles of catalase and Cu,Zn-SOD.

Pulsatile stretch stimulates vascular endothelial growth factor (VEGF) secretion by cultured rat cardiac myocytes

Evidence has accumulated that vascular endothelial growth factor (VEGF) is expressed in the heart, and its expression is markedly increased in response to hypoxia. Recently, it was shown that pulsatile myocardial stretch in vivo markedly enhanced VEGF mRNA level in the heart. To investigate whether pulsatile mechanical stretch really stimulates VEGF expression by cardiac myocytes, using an in vitro preparation, we examined the secretion of VEGF into the culture media from cardiac myocytes subjected to pulsatile stretch. We found that pulsatile mechanical stretch induced rapid secretion of VEGF by cultured rat cardiac myocytes and mRNA expression of VEGF and VEGF receptors in the cardiac myocytes. We also found that the stretch-induced secretion of VEGF was at least in part mediated by TGF-beta. These data provide the direct evidence that mechanical overload itself can induce VEGF secretion by cardiac myocytes, which may play a role in ameliorating the relative myocardial hypoxia.

Evidence of cell-mediated cardiac myocyte injury involved in the heart failure of a patient with progressive systemic sclerosis

A 54-year-old woman with progressive systemic sclerosis (PSS) was admitted to hospital because of dyspnea and chest pain. Echocardiogram revealed diffuse hypokinesis of the left ventricle (ejection fraction 24%). Methylprednisolone, heparin, and diuretics were administered, without benefit. Anemia, thrombocytopenia, and renal dysfunction rapidly progressed, and she died of heart failure on the 14th hospital day. Immunohistochemical study of the myocardial tissue showed mild to moderate cell infiltration, mainly consisting of natural killer (NK) cells, macrophages, cytotoxic T lymphocytes (CTLs), and T helper cells. Perforin, a cytolytic factor, was expressed in the infiltrating CTLs and NK cells, indicating that these cells were activated killer cells. Furthermore, human leukocyte antigen classes I and II, intercellular adhesion molecule-1, as well as costimulatory molecules B7-1, B7-2, and CD40, all of which are known not to be expressed in cardiac myocytes under normal conditions, were moderately to strongly expressed in cardiac myocytes. There was no detectable level of enterovirus genomes in the polymerase chain reaction products from the myocardial tissue of this patient. These findings strongly suggest that the infiltrating killer cells recognized cardiac myocytes as target cells and directly damaged them by releasing perforin. Enhanced expression of these antigens may have played an important role in the activation and cytotoxicity of the infiltrating killer cells. Absence of enterovirus genomes in the myocardial tissue may suggest that this autoimmune process is primarily induced by PSS.

Observation of ultrastructural changes in cultured retinal pigment epithelium following exposure to blue light

BACKGROUND

The retina can be damaged by light even when levels of energy are well below the threshold for thermal damage, and the experimental damage of the retinal pigment epithelium (RPE) may be induced more easily by blue light than by longer wavelengths of visible light. The present study demonstrates the ultrastructural damage produced by exposure to blue light in cultured RPE.

METHODS

Long-Evans rats were enucleated 8-10 days after birth for primary culture. One week after seeding, the monolayer culture of RPE cells was exposed to a cool blue light (wavelength = 440 +/- 10 nm) for 36 h (12 h/day, 3 days) at 2.0 mW/cm2. Transmission electron microscopy was used to compare the exposed RPE with the control. The entire experiment was repeated 3 times independently.

RESULTS

The cytoplasm of the exposed RPE exhibited degenerative changes, such as large whorls of membrane, lamellar whorls and whorled inclusions.

CONCLUSION

The RPE cells can be damaged directly by blue light after excluding the possible influence of phagosomes. This primary culture of RPE can also serve as an in vitro model for the study of light damage to the RPE.

Expression of costimulatory molecule CD40 in murine heart with acute myocarditis and reduction of inflammation by treatment with anti-CD40L/B7-1 monoclonal antibodies

Evidence has accumulated that antigen-specific T cells infiltrate the heart and play an important role in the pathogenesis of viral myocarditis. Costimulatory molecules such as B7s and CD40 expressed on antigen-presenting cells are known to play a critical role for antigen-specific T-cell activation to occur. To investigate the role for a costimulatory molecule, CD40, in the development of acute viral myocarditis, we first analyzed the expression of CD40 in the hearts of mice with acute viral myocarditis induced by Coxsackievirus B3. We also evaluated the induction of CD40 in cultured cardiac myocytes treated with interferon gamma in vitro. Second, we analyzed the cytokine production by cultured cardiac myocytes by stimulation with anti-CD40 monoclonal antibody (mAb) in vitro. Third, we examined the effects of in vivo administration of anti-CD40L/B7-1 mAbs on the development of acute viral myocarditis. We found that Coxsackievirus B3-induced murine acute myocarditis results in enhanced expression of CD40 on cardiac myocytes. The expression of CD40 on cardiac myocytes could be induced by interferon gamma in vitro. We also found that the production of interleukin-6 by cardiac myocytes was stimulated with anti-CD40 mAb and that in vivo anti-CD40L/B7-1 mAb treatment significantly decreased the myocardial inflammation. Our findings strongly suggest that CD40 plays an important role in the development of acute viral myocarditis and raise the possibility of immunotherapy with anti-CD40L/B7-1 mAbs to prevent T cell-mediated myocardial damage in viral myocarditis.

Vascular endothelial growth factor (VEGF) activates Raf-1, mitogen-activated protein (MAP) kinases, and S6 kinase (p90rsk) in cultured rat cardiac myocytes

Rapid activation of intracellular signaling cascades is induced in cardiac myocytes in response to various external stresses. Vascular endothelial growth factor (VEGF) is a potent angiogenic mitogen secreted from tumor cells and cells exposed to hypoxia such as ischemic myocardial cells. To clarify the mechanisms of how cardiac myocytes respond and adapt to ischemic stresses, we investigated the intracellular signaling cascades in cultured rat cardiac myocytes in response to VEGF. We show that rapid activation of mitogen-activated protein kinase kinase kinase (MAPKKK) of Raf-1, MAP kinases, and S6 kinase (p90rsk) was induced in cardiac myocytes in response to VEGF. This activation of MAP kinases was also induced in fibroblasts. VEGF also caused phosphorylation of the activating transcription factor 2. Furthermore, VEGF strongly induced a transcription factor jun-B mRNA in cardiac myocytes. These results indicated that MAP kinase pathway is rapidly activated in cardiac myocytes and fibroblasts in response to VEGF. It is strongly suggested that cardiac myocytes are one of the targets of VEGF and that cardiac response to ischemic stresses may be at least partly mediated by VEGF.

Restricted usage of T-cell receptor Valpha-Vbeta genes in infiltrating cells in the aortic tissue of a patient with atherosclerotic aortic aneurysm

We report a rare case of an atherosclerotic aortic aneurysm with lymphocyte infiltration in which T-cell receptor (TCR) Valpha as well as Vbeta gene usage was restricted. Immunohistochemical studies showed that the infiltrating cells mainly consisted of macrophages, natural killer (NK) cells, cytotoxic T lymphocytes (CTLs) and T-helper (Th) cells, and that there were almost no infiltrating delta T lymphocytes, and human leukocyte antigen (HLA) class I and 65-kD heat-shock protein (HSP-65) was not strongly expressed in the aortic tissue. Although the immunohistochemical data were consistent with an ordinary atherosclerotic aortic aneurysm, in which TCR Valpha-Vbeta gene usage is known to be polyclonal, the restricted TCR gene usage suggests that a certain autoimmune mechanism was involved in the pathogenesis of this case similar to Takayasu's arteritis, in which massive infiltration of delta T lymphocytes and strong expression of HSP-65 in the aortic tissue are characteristic.

Hepatitis C virus infection and heart diseases: a multicenter study in Japan

As a collaborative research project of the Committees for the Study of Idiopathic Cardiomyopathy, a questionnaire was sent out to 19 medical institutions in Japan in order to examine the possible association between hepatitis C virus (HCV) infection and cardiomyopathies. Hepatitis C virus antibody was found in 74 of 697 patients (10.6%) with hypertrophic cardiomyopathy (mean age, 57.7 years) and in 42 of 663 patients (6.3%) with dilated cardiomyopathy (mean age, 56.5 years); these prevalences were significantly higher than that found in volunteer blood donors in Japan (2.4%, 50-59 years of age, each p<0.0001). The prevalence was significantly higher in patients suffering from hypertrophic cardiomyopathy as opposed to those with dilated cardiomyopathy (p<0.01). The presence of HCV antibody was detected in 650 of 11,967 patients (5.4%) patients seeking care in 5 academic hospitals. Various cardiac abnormalities were found among these patients, arrhythmias being the most frequent. These observations suggest that HCV infection is an important cause of a variety of otherwise unexplained heart diseases.

Overexpression of manganese-superoxide dismutase prevents methylmercury toxicity in HeLa cells

HeLa cells were stably transformed with plasmid constructs that allowed constitutive expression of antioxidant enzymes such as catalase, glutathione peroxidase (GSH-Px), Cu,Zn-superoxide dismutase (Cu,Zn-SOD) or Mn-superoxide dismutase (Mn-SOD) to examine the involvement of reactive oxygen generation in methylmercury toxicity. Overexpression of catalase, GSH-Px or Cu,Zn-SOD did not affect the sensitivity of HeLa cells against methylmercury. However, the sensitivity of HeLa cells against methylmercury was decreased by overexpression of Mn-SOD, an enzyme localized in matrix of mitochondria and which decomposes superoxide anions. These results suggest that formation of superoxide anions in the mitochondria might be involved in the mechanism of the cytotoxicity of methylmercury.

Effects of in vivo administration of anti-B7-1/B7-2 monoclonal antibodies on murine acute myocarditis caused by coxsackievirus B3

In viral myocarditis, we previously reported that antigen-specific T cells infiltrate the heart and play an important role in the pathogenesis of myocardial damage. For antigen-specific T-cell activation to occur, it is necessary for T cells to receive costimulatory signals provided by costimulatory molecules expressed on antigen-presenting cells as well as main signals provided by binding of T-cell receptors to antigens. To investigate the roles of costimulatory molecules B7-1 and B7-2 in the development of acute viral myocarditis, we first analyzed the expression of B7-1/B7-2 in the hearts of mice with acute viral myocarditis induced by coxsackievirus B3 (CVB3). Second, we evaluated the induction of B7-1/B7-2 in cultured cardiac myocytes treated with interferon gamma (IFN-gamma). Third, we examined the effects of in vivo administration of anti-B7-1/B7-2 monoclonal antibodies (mAbs) on the development of acute viral myocarditis. We found that CVB3-induced murine acute myocarditis resulted in enhanced expression of B7-1/B7-2 in cardiac myocytes. The expression of B7-1/B7-2 in cardiac myocytes could be induced in vitro by IFN-gamma. We found that in vivo anti-B7-1 mAb treatment markedly decreased myocardial inflammation, whereas anti-B7-2 mAb treatment abrogated the protective effect of anti-B7-1. Our findings indicate that distinct roles for B7-1 and B7-2 antigens are involved in the development of acute viral myocarditis and raise the possibility of immunotherapy with anti-B7-1 mAb to prevent T-cell-mediated myocardial damage in viral myocarditis.

Effects of intranasal administration of recombinant murine interferon-gamma on murine acute myocarditis caused by encephalomyocarditis virus

BACKGROUND

Viral myocarditis has been strongly implicated in the pathogenesis of dilated cardiomyopathy as well as acute myocarditis. Among the antiviral therapies, interferons (IFNs) have been widely studied and become very important in clinical practice.

METHODS AND RESULTS

To investigate the possibilities of IFN therapy in viral myocarditis, we analyzed the effects of recombinant murine interferon (mIFN)-gamma and natural mIFN-alpha/beta by the intranasal and intramuscular routes on the development of acute murine myocarditis caused by encephalomyocarditis virus. Both mIFN-gamma and mIFN-alpha/beta treatment by either route significantly increased the survival rate; none of the mIFN-gamma-treated mice died. The effect of mIFN-gamma was significantly greater than that of mIFN-alpha/beta. Furthermore, intranasal administration of mIFN-gamma significantly suppressed virus replication and inflammation in the heart.

CONCLUSIONS

Our data demonstrate that IFN therapy, especially intranasal administration of IFN-gamma, dramatically improved the prognosis of acute murine viral myocarditis by suppressing virus replication and raises the possibility of antiviral therapy with IFN-gamma in patients with acute myocarditis.

Expression of costimulatory molecules B7-1, B7-2, and CD40 in the heart of patients with acute myocarditis and dilated cardiomyopathy

BACKGROUND

In patients with acute myocarditis and dilated cardiomyopathy (DCM), we previously reported that antigen-specific T cells infiltrate the heart and play an important role in the myocardial damage involved. For antigen-specific T-cell activation to occur, it is necessary for T cells to receive a costimulatory signal provided by costimulatory molecules expressed on antigen-presenting cells (APCs) as well as the main signal provided by binding of T-cell receptors to the antigen.

METHODS AND RESULTS

To investigate the roles of the costimulatory molecules B7-1, B7-2, and CD40 in the development of acute myocarditis and DCM, we analyzed the expression of these antigens in the myocardial tissues of patients with acute myocarditis and DCM. We also examined the expression of a cytolytic factor, perforin, in the infiltrating cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, because both killer lymphocytes are thought to damage B7-1-expressing APCs. We found that B7-1, B7-2, and CD40 were moderately to strongly expressed in the cardiac myocytes of patients with acute myocarditis. Weak to moderate expression of these antigens was also found in the cardiac myocytes of patients with DCM. There was infiltration of perforin-expressing CTLs and NK cells in the myocardial tissues of patients with acute myocarditis and DCM.

CONCLUSIONS

Our findings strongly suggest that expression of B7-1, B7-2, and CD40 antigens on cardiac myocytes may make them APCs for CTLs and NK cells and that they may play an important role in the direct myocardial damage by these killer cells in acute myocarditis and DCM.

Perforin-secreting killer cell infiltration in the aortic tissue of patients with atherosclerotic aortic aneurysm

Cell-mediated immunity has been implicated in the pathogenesis of vascular cell injury in patients with atherosclerotic aortic aneurysms. To clarify the immunologic mechanisms involved, we examined the expression of a cytolytic factor, perforin, in infiltrating cells from aortic tissue samples taken from 6 patients with atherosclerotic aortic aneurysms. Immunohistochemical studies showed that the infiltrating cells consisted mainly of macrophages, natural killer (NK) cells, cytotoxic T lymphocytes (CTLs), and T helper cells, and that perforin was expressed in NK cells and CTLs. Immunoelectron microscopic studies demonstrated that the infiltrating cells released massive amounts of perforin directly on to the surface of arterial vascular cells. These findings provide the first direct evidence that some of the infiltrating cells in the aortic tissue consist of killer cells, and strongly suggest that these killer cells, especially NK cells and CTLs, may play a critical role in the vascular cell injury caused by atherosclerotic aortic aneurysm by releasing perforin.

Hypoxia and hypoxia/reoxygenation activate p65PAK, p38 mitogen-activated protein kinase (MAPK), and stress-activated protein kinase (SAPK) in cultured rat cardiac myocytes

We previously reported that both hypoxia and hypoxia followed by reoxygenation (hypoxia/reoxygenation) rapidly activate Src family tyrosine kinases and p21ras in cultured rat cardiac myocytes. This was followed by the sequential activation of mitogen-activated protein kinase kinase kinase (MAPKKK) activity of Raf-1, MAP kinase kinase (MAPKK), MAPKs (p44mapk and p42mapk, also called extracellular signal-regulated protein kinase [ERK]1 and ERK2, respectively), and S6 kinase (p90rsk). In this study, we demonstrated that both hypoxia and hypoxia/reoxygenation caused rapid activation of stress-activated MAPK signaling cascades involving p65PAK, p38MAPK, and SAPK. These stimuli also caused phosphorylation of activating transcription factor (ATF)-2. Because p65PAK is known to be upstream of p38MAPK and also be a target of p21rac-1, which belongs to the rho subfamily of p21ras-related small GTP-binding proteins, these results strongly suggested that two different stress-activated MAPK pathways distinct from the classical MAPK pathway were activated in response to hypoxia and hypoxia/reoxygenation in cardiac myocytes.

Apomorphine inhibits the growth-stimulating effect of retinal pigment epithelium on scleral cells in vitro

Visual deprivation of the chicken eye causes axial elongation with high myopia. The cartilaginous layer of the myopic sclera shows an increase of mitotic activity. Previous studies reported that the in vivo administration of apomorphine, a dopamine nonselective agonist, effectively prevents visual-deprivation myopia. Because the retinal pigment epithelium (RPE) regulates growth of the sclera as we and others have shown previously, it is speculated that the RPE cells may play an important role in this preventive effect of apomorphine. In this study, to clarify the mechanism by which the administration of apomorphine inhibits the proliferation of scleral chondrocytes in vivo, we have investigated the effect of apomorphine on the proliferation of scleral chondrocytes with or without co-cultured RPE cells in vitro. We previously demonstrated that cell proliferation of scleral chondrocytes remarkably increases with co-cultured RPE cells. In this study, we found that apomorphine at concentrations of higher than 2 x 10(-5) M dramatically reduced the growth-stimulatory effect of RPE cells on the scleral chondrocytes, whereas the inhibitory effect of apomorphine on the proliferation of scleral chondrocytes without RPE cells was very little. Our results strongly suggest that apomorphine may reduce the production and/or release of some humoral factors from RPE cells, which stimulate the growth of scleral cells. There is also a possibility that apomorphine reduces the reactivity of scleral cells to the humoral factors released from RPE cells.

Active oxygen generation as a possible mechanism of selenium toxicity

Selenium plays an important role in scavenging active oxygen (AO) species as an essential constituent of glutathione peroxidase. On the other hand, several reports proposed a possible induction of toxic AO by selenium compounds in vitro. However, some of these experiments including ours, were revealed to conclude on the basis of experimental artifacts, and to have problems in the interpretation of data. Methods or principles so far used for the detection of AO species generated by selenium compound were measurement of chemiluminescence from lucigenin or luminol by AO species, the spectrophotometric analysis of reduction of ferricytochrome c or nitroblue tetrazolium (NBT) by superoxide anion (O2-), electron spin resonance (ESR) spectra using dimethylpyrroline oxide (DMPO) as a spin trapping agent, the deoxyribose decomposition by hydroxyl radical (HO.), the salicylate hydroxylation by HO., and the strand breakage of DNA by AO. Many of these methods together with their principles seem to have some defects which prevent clear conclusion as stated below. (i) Lucigenin was found to mediate the formation of O2- in the presence of selenite and reduced glutathione (GSH). Therefore, lucigenin is not a suitable reagent. (ii) Luminol may also mediate O2- generation in the presence of HO.. (iii) ferricytochrome c can be reduced to ferrocytochrome c in the mixture of selenite and GSH in the absence of oxygen. Moreover, the spectrophotometric method is interfered by turbidity of elemental selenium formed under some conditions in the reaction mixture containing selenite and GSH. (iv) NBT is also reduced by selenium compounds in the absence of O2. (v) ESR signals of AO species were obtained in the reaction mixture containing selenite and GSH, or in the solution of hydrogen selenide in the presence of O2. However, selenide decomposed spin adduct of DMPO with HO. (DMPO-OH). Therefore, the intensity of the signals is not quantitative. (vi) CuZn-SOD is not necessarily a good tool to prove the involvement of O2- because it enhanced HO. generation in the reaction mixture containing selenite and GSH. Thus, we would like to emphasize that carefully designed experiments are required to further identify the molecular species of active oxygen induced by selenium compounds.

Expression of cytokine mRNAs in murine hearts with acute myocarditis caused by coxsackievirus b3

In murine acute viral myocarditis, natural killer (NK) cells infiltrate the heart first, followed by activated T-cells, which play an important role in the pathogenesis of the myocardial damage. Because of their multipotential effects, cytokines are thought to play a role in the induction and development of these immune processes. To clarify in more detail the precise mechanism of the cytokine networks involved, the expression of various cytokine mRNAs has been investigated in myocardial cells infected with Coxsackievirus B3 (CVB3) in vivo and in vitro by a semiquantitative polymerase chain reaction (PCR) method. Interleukin (IL)-1 alpha, IL-1 beta, IL-6, tumour necrosis factor (TNF)-alpha, and TNF-beta were expressed almost throughout the early phase of virus infection with some variations. IL-2, IL-3, IL-4, IL-10, interferon (IFN)-gamma, granulocyte/macrophage colony stimulating factor (GM-CSF), and IL-2 receptor (IL-2R) were mainly expressed by the infiltrating cells. TNF-alpha, TNF-beta, and IL-1 beta were also expressed partly by the infiltrating cells. T-helper (Th)1-related cytokines (IL-2, IFN-gamma, and TNF-beta) were more strongly expressed than Th2-related cytokines (IL-4 and IL-10) in vivo, indicating that the Th cells which infiltrated the heart and mediated the immune responses in the early phase of acute myocarditis were mainly of Th1-type.