Multiferroic properties of o-LuMnO3 controlled by b-axis strain.

Strain is a leading candidate for controlling magnetoelectric coupling in multiferroics. Here, we use x-ray diffraction to study the coupling between magnetic order and structural distortion in epitaxial films of the orthorhombic (o-) perovskite LuMnO(3). An antiferromagnetic spin canting in the E-type magnetic structure is shown to be related to the ferroelectrically induced structural distortion and to a change in the magnetic propagation vector. By comparing films of different orientations and thicknesses, these quantities are found to be controlled by b-axis strain. It is shown that compressive strain destabilizes the commensurate E-type structure and reduces its accompanying ferroelectric distortion.

Effects of fermented milk intake and physical activity on the suppression of age-related decline in physical fitness among the elderly.

Physical deterioration in the elderly can lead to disability and mortality. Although the intake of fermented milk has been recently attracting attention as a proposed measure to prevent physical weakness, studies and findings are limited. Here, we investigated the effect of intake of fermented milk products on suppression of age-related decline in physical fitness through a long-term epidemiological study of community-dwelling elderly people who are capable of independent living. A retrospective analysis was conducted on 581 elderly people aged 65-92 years from the Nakanojo Study, with the addition of a 5-year prospective analysis on 240 elderlies. Subjects were arbitrarily grouped on the basis of questionnaire estimates of fermented milk products intake (<3 or ≥3 days/week) and pedometer/accelerometer-determined patterns of physical activity (<7,000 or ≥7,000 steps/day). After adjustment for potential confounders, the retrospective study showed that the group consuming fermented milk products ≥3 days/week showed significantly faster walking speeds than the <3 days/week group. The group taking ≥7,000 steps/day had a significantly faster walking speed than the group taking <7,000 steps/day. Those who did both walked the fastest, indicating an additive effect. Adding protein or energy intake as a covariate to the potential confounders found a correlation between the intake of fermented milk products and walking speed, suggesting that the effect of fermented milk products consumption is independent of nutritional intake status, due to the beneficial properties of bacteria included in fermented milk. The 5-year prospective study confirmed a clear relationship between the frequency of consumption of fermented milk products and the suppression of preferred walking speed decline. Our findings suggest that habitual intake of fermented milk contributes to the suppression of walking speed decline in elderly people.

Relationships between dietary diversity and gut microbial diversity in the elderly.

Diet is considered as a major driver of gut microbiota composition. However, little is known about the relationship between overall dietary balance and gut microbiota, especially in the elderly. Here, using the Quantitative Index for Dietary Diversity (QUANTIDD), we analysed the relationships between dietary diversity and gut microbiota diversity in 445 Japanese subjects aged 65-90 years. We also examined the effect of age by comparing the young-old group aged 65 to 74 years (<75 years group; n=246) and the old-old group aged 75 years and older (≥75 years group; n=199). QUANTIDD showed significant positive relationships with Pielou's evenness and Shannon indices, two α-diversity indices related to the uniformity of species distribution. This suggests that a more diverse diet is associated with a more uniform abundance of various bacterial groups, rather than a greater variety of gut bacteria. QUANTIDD also showed significant positive associations with the abundance of Anaerostipes, Eubacterium eligens group, and Eubacterium ventriosum group, which produce short-chain fatty acids (SCFAs) and are beneficial to health. Negative association was found with the abundance of Ruminococcus gnavus group, which produces inflammatory polysaccharides. Positive associations between QUANTIDD and α-diversity indices or the abundance of specific bacterial groups were identified among all subjects and in the <75 years group, but not in the ≥75 years group. Our results suggest that dietary diversity contributes to the diversity of the gut microbiota and increases the abundance of SCFAs-producing bacteria, but only up to a certain age. These findings help to understand the complex relationship between diet and gut microbiota, and provide hints for specific dietary interventions to promote beneficial gut microbiota in the elderly.

Characteristics of gut microbiome, organic acid profiles and viral antibody indexes of healthy Japanese with live Lacticaseibacillus detected in stool.

To estimate the health-promoting effects of Lacticaseibacillus paracasei (previously Lactobacillus casei) strain Shirota (LcS) that reached the lower gastrointestinal tract alive, we investigated the characteristics of gut microbiome, organic acid profiles, defecatory symptoms and serum viral antibody indexes of healthy Japanese adults between the group in whom live LcS was detected or not from stool. The ß-diversity index of the gut microbiome constituted a significant difference between the live-LcS-detected-group (LLD) and the live-LcS-not-detected-group (LLnD). In the LLD, the Bifidobacteriaceae, Lactobacillaceae, and Coriobacteriaceae counts were significantly higher, and the succinate concentration was significantly lower than that in the LLnD. The serum herpes simplex virus (HSV) immunoglobulin (Ig)M antibody index in the LLD tended to be lower than that of the LLnD in HSV IgG-positive subjects. Of the LLD, those in the fermented milk products containing LcS (FML)-high-frequency-group (FML-HF) and those in the FML-low-frequency-group (FML-LF) had different gut microbiome and organic acid profiles. However, the pattern of differences between FML-HF and FML-LF was dissimilar those between LLD and LLnD. In contrast, among subjects with FML-LF, those in the group with LLD in stool (LF-LLD) and those in the LLnD in stool (LF-LLnD) showed a similar pattern of differences in their gut microbiome and organic acid profiles as those in the LLnD and LLD. The LLD and LF-LLD commonly had lower caloric and carbohydrate intakes from the diet than their respective control groups. In this study, we found that the presence of live LcS in stool is associated with a healthy gut environment and inhibition of the reactivation of latently infected viruses in the host. However, these health-promoting effects on the host were not related to the frequency of FML intake. Furthermore, dysbiosis of the gut microbiome and diet including caloric intake was related to the viability of ingested LcS in the gut.

Decrease of blood dendritic cells and increase of tissue-infiltrating dendritic cells are involved in the induction of Sjögren's syndrome but not in the maintenance.

We have demonstrated previously that, in primary Sjögren's syndrome (SS), immature myeloid dendritic cells (DCs) are decreased in blood and mature myeloid DCs are accumulated in salivary glands, suggesting recruitment of the myeloid DCs from blood to salivary glands. To verify whether this finding is universal in patients of not only primary SS but also secondary SS, in this study we analysed the blood DCs of secondary SS patients. We examined 24 secondary SS and 29 primary SS patients. A direct correlation between the decreased number of myeloid DCs and the duration of Sicca syndrome in primary and secondary SS was observed; namely, the reduction of myeloid DCs in blood was restored spontaneously with duration time of Sicca syndrome. We also examined the immunohistochemical staining of salivary glands of SS patients with monoclonal antibodies against fascin, CD11c and human leucocyte antigen DR (HLA-DR). Fascin(+) or CD11c(+)/HLA-DR(+) mononuclear cells were present in the salivary glands of secondary SS patients, as in primary SS. However, fascin(+) mononuclear cells were barely detected in the salivary glands of a chronic phase of SS patients. We also found a negative correlation between the frequency of blood myeloid DCs and salivary gland-infiltrating DCs in secondary SS patients, as well as primary SS. Our results suggest that the reduction of blood myeloid DCs and preferential trafficking of myeloid DCs into salivary glands is a common event in the early stage of SS. Myeloid DCs may play essential roles in the pathogenesis of Sicca syndrome of SS by initiating T helper cell immune responses.

Tubular epithelial cells have the capacity to transdifferentiate into CD68-positive macrophage-like cells by oxidative stress.

OBJECTIVE: The present study was intended to assess transdifferentiation from tubular epithelial cells to macrophage- like cells. METHODS: Puromycin aminonucleoside nephrotic rats were sacrificed at days 4, 8, 24 and 112. We immunohistochemically evaluated CD68, CD163, and cytokeratin AE1/AE3, known as markers for macrophages and tubular epithelial cells. Nitrotyrosine, gp91(phox) and Rac 1 expressions was also analyzed. CD68 expression in cultured murine proximal tubular epithelial cells (mProx) stimulated by crude and pure BSA was examined by flow cytometry and immunofluorescence. RESULTS: The tubular CD68-positive cells were observed on day 112. Immunoelectronmicroscopy revealed that some CD68-positive cells showed brush borders on the cell membrane and some of cytokeratin-positive tubular cells also expressed CD163 in mirror sections. The tubular CD68-positive cells were also positive for nitrotyrosine, gp91 (phox) and Rac 1. They contained lipid in their cytoplasm. Crude BSA, containing free fatty acid, induced CD68 expression in a dose- and time-dependent manner in mProx, but not pure BSA. The surface expression of CD68 was increased by high dose and long term stimulation with crude BSA as shown by immunofluorescence. CONCLUSIONS: We confirmed that tubular epithelial cells have the capacity to transdifferentiate to CD68-positive macrophage-like cells, which may be linked to oxidative stress.

Expert recommendations on the challenges of hypertension in Asia.

A consensus meeting of leading Asian hypertension experts was held in January 2007 in Seoul, Korea, to discuss how to address the growing challenge of hypertension management in the region. This report summarises key recommendations from the group, including: raising public awareness about the impact of hypertension; improving physician education and training; increasing early detection, for example through routine blood pressure measurement; and development and adoption of pan-Asian treatment guidelines, which would greatly facilitate research into hypertension and its management. The group conclude that these challenges can only be met through a collaborative effort of government, healthcare professionals, food and healthcare industries, and patients and the public. Food and healthcare industries need to develop healthy foods and support healthy living programmes, while increasing research into antihypertensive medications in Asia. Government officials and policy makers need to be made aware of the value of investing in hypertension awareness, prevention and management programmes.

Enhancement of tumor induction in rats with Moloney murine sarcoma virus by a "new" method based on direct injection into fetuses.

Undiluted, fivefold-diluted, and 25-fold-diluted doses of a stock of Moloney murine sarcoma virus were injected directly, in a volume of 0.025 ml, into the backs of fetal Sprague-Dawley rats by laparotomy through the uterine wall at 18 days of gestation. During the first 8 weeks after birth the young responded to the virus with remarkably high but dose-dependent incidences of neoplasms. When a one-fifth dilution of the virus preparation was inoculated at fetal ages 16, 18, and 20 days, the incidences of lesions decreased with advancing fetal age. The tumors developed preferentially at the virus inoculation site and/or in the proximal parts of the extremeties; all were considered to be of mesenchymal derivation, i.e., malignant mesenchymoma, rhabdomyosarcoma, osteosarcoma, fibrosarcoma or fibromyxosarcoma, hemangiosarcoma, plasmacytoma, and a giant cell tumor. This injection procedure provided us with a valuable experimental tool for the rapid screening or testing of potential chemical carcinogens and other biologic studies.

Substrate turnover by transporters curtails synaptic glutamate transients.

Although inhibitors of glutamate transport prolong synaptic currents at many glutamate synapses, the cause of the current prolongation is unclear. Transport inhibitors may prolong synaptic currents by simply interfering with synaptic glutamate binding to transporters, by inhibiting substrate translocation, or by promoting accumulation of ambient glutamate, which may act cooperatively at receptors with synaptic glutamate. We show that reversal of the membrane potential of astrocytes surrounding the synapse prolongs synaptic currents but does not decrease the apparent affinity of transporters or significantly alter glutamate-dependent kinetics of macroscopic transporter currents in excised membrane patches. Positive membrane potentials do not affect binding of a nontransported glutamate analog, nor do positive membrane potentials alter the number of transporters available to bind analog. We also test the hypothesis that glutamate accumulation during uptake inhibition by transporter substrates is the direct cause of synaptic current prolongations. Transporter substrates elevate ambient glutamate near synapses by fostering reverse transport of endogenous glutamate. However, increases in ambient glutamate cannot account for the prolongations of synaptic currents, because a nonsubstrate transport inhibitor does not foster reverse uptake yet it prolongs synaptic currents. Moreover, exogenous glutamate does not mimic synaptic current prolongations induced by substrate inhibitors. These results provide strong support for a major role of substrate translocation in determining the time course of the glutamate concentration transient at excitatory synapses.

Inhibition of annexin V-dependent Ca2+ movement in large unilamellar vesicles by K201, a new 1,4-benzothiazepine derivative.

Examination was made of the effect of annexin V on Ca2+ movement into large unilamellar vesicles (LUV) using fura-2, a calcium-sensitive fluorescent dye. To avoid the possible difficulties relating to the addition of annexin V and/or Ca2+ in fura-2-loaded LUV, the burst method was used. LUV, preincubated with rat annexin V in the presence of Ca2+, were collected by centrifugation and resuspended, and then burst with Triton X-100 in the presence of fura-2. Inward Ca2+ movement across the artificial lipid membrane was measured by determination of fura-2 fluorescence due to the leaked Ca2+ from ruptured LUV. The observed Ca2+ signal increased dependent on annexin V and Ca2+ concentrations, whereas bovine serum albumin did not affect this signal up to 1 microM. Thus, annexin V shows Ca2+ channel activity in LUV. K201, a novel 1,4-benzothiazepine, inhibited inward Ca2+ movement into LUV caused by annexin V in a dose-dependent manner. In the presence of 50 nM annexin V and 400 microM Ca2+, 3 microM K201 showed significant inhibition of Ca2+ movement due to annexin V, and 50% inhibition was achieved at 25 microM K201. On the other hand, diltiazem had no such effect even at 30 microM. K201 is thus shown to have inhibitory activity on inward Ca2+ movement due to annexin V in artificial vesicles and may prove useful as a probe for elucidating the functions of annexin V in vivo.

Cardioprotective mechanism of ischemic preconditioning is impaired by postinfarct ventricular remodeling through angiotensin II type 1 receptor activation.

BACKGROUND: Activation of protein kinase C-linked receptors and subsequent opening of the mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel are crucial in preconditioning (PC). This study examined whether postinfarct ventricular remodeling interferes with the PC mechanism. METHODS AND RESULTS: Two weeks before isolation of hearts, rabbits underwent a sham operation or coronary ligation (COL) to induce remodeling. Isolated buffer-perfused hearts were subjected to 30-minute global ischemia/2-hour reperfusion, and infarct size was expressed as a percentage of the left ventricle (%I/LV), from which the scarred infarct by COL was excluded. Although %I/LV was similar in sham-operated and remodeled hearts (52.9+/-6.5% versus 45.8+/-5.2%), PC with 2 episodes of 5-minute ischemia protected sham-operated but not remodeled hearts (%I/LV=18.1+/-2.5% versus 54.8+/-2.9%, P<0.05). Infusion of valsartan (10 mg x kg(-1). d(-1), an angiotensin II type 1 (AT(1)) receptor blocker, for 2 weeks after COL prevented the ventricular remodeling and preserved the response to PC (%I/LV=27.4+/-3.8%), although valsartan alone did not change %I/LV. Diazoxide, a mitoK(ATP) channel opener, protected both sham-operated and remodeled hearts (%I/LV=14.1+/-3.1% and 8.3+/-3.6%). CONCLUSIONS: The myocardium remodeled after infarction is refractory to PC, which is probably due to interruption of cellular signaling by PC upstream of mitoK(ATP) channels. An AT(1) receptor blocker is beneficial not only for suppression of ventricular remodeling but also for preservation of the PC mechanism.

Activation of adenosine receptors before ischemia enhances tolerance against myocardial stunning in the rabbit heart.

OBJECTIVES: This study examined whether stimulation of adenosine receptors before ischemia enhances myocardial resistance to stunning in vivo. BACKGROUND: We previously demonstrated the attenuation of myocardial stunning by ischemic preconditioning through adenosine receptor activation in rabbits. METHODS: 1) To confirm the efficacy of an intravenous infusion of adenosine to stimulate adenosine receptors in the heart, we assessed the effect of an adenosine infusion on the inotropic response to an isoproterenol challenge. 2) Myocardial stunning was induced by 10 min of coronary occlusion and reperfusion. The regional thickening fraction was monitored by an epicardial Doppler sensor. Rabbits were pretreated with either no drug (control group), adenosine, 8-phenyltheophylline or a combination of 8-phenyltheophylline plus adenosine. RESULTS: An intravenous infusion of adenosine at 0.15 mg/kg body weight per min attenuated by 50% the elevation of left ventricular dP/dtmax by isoproterenol (0.075 microgram/kg per min). The same dose of adenosine infused for 15 min before ischemia significantly improved the postischemic recovery of the thickening fraction, and the thickening fraction at 30 min reperfusion was 76.8 +/- 3.3% (mean +/- SE) of the baseline value, which was significantly higher than the control value (42.9 +/- 4.5%). The relation between thickening fraction and systolic left ventricular pressure after reperfusion was shifted toward higher thickening fraction by adenosine. This beneficial effect of adenosine was not detected in rabbits given 8-phenyltheophylline before adenosine, and 8-phenyltheophylline-treated rabbits showed a time course of thickening fraction similar to that in the control group. CONCLUSIONS: An intravenous infusion of adenosine is capable of protecting rabbit hearts against stunning through adenosine receptor activation.

Right ventricular abnormalities assessed by myocardial single-photon emission computed tomography using technetium-99m sestamibi/tetrofosmin in right ventricle-originated ventricular tachyarrhythmias.

OBJECTIVES: We sought to determine whether right ventricular (RV) perfusion imaging with technetium-99m (Tc-99m) sestamibi or tetrofosmin single-photon emission computed tomography has diagnostic benefit for RV-originated ventricular tachyarrhythmias (RVT). BACKGROUND: Identification of RV abnormalities is clinically important to establish RVT etiology. METHODS: Forty-seven patients with RVT (23 with idiopathic and 24 with organic RVT due to arrhythmogenic RV or dilated cardiomyopathy, cardiac sarcoidosis or myocarditis) were compared to 25 control subjects. Right ventricular uptake score, as assessed by modified tomographic imaging, and regional RV count relative to peak left ventricular (LV) count (RV/LV count ratio) were compared with RV regional and global function. RESULTS: Regional RV uptake score correlated well with the RV/LV count ratio, and segmental abnormality was more frequently (p = 0.001) detected in the organic RVT group (22 [92%] of 24 patients) than in the idiopathic RVT group (4 [17%] of 23 patients) or the control group (8 [32%] of 25 patients). The total RV score (8.4+/-3.8) in the organic RVT group was significantly lower than that in the idiopathic RVT group (15.6+/-1.6) or the control group (15.1+/-1.8). The total RV score correlated with RV EF (r = 0.702, p<0.001). A total RV score <12 differentiated the organic RVT group from the other two groups, with a sensitivity of 79% and a specificity of 100%. The asynergic RV regions had a significantly lower RV/LV count ratio and RV score as compared with the nonasynergic regions and were identified by RV assessment, with a sensitivity of 76.1% and a specificity of 76.6%. CONCLUSIONS: Right ventricular perfusion tomography using a Tc-99m-labeled tracer is clinically useful for the noninvasive detection of RV myocardial damage in patients with RVT and for differentiating organic from idiopathic RVT.

Infarct size limitation by a new Na(+)-H+ exchange inhibitor, Hoe 642: difference from preconditioning in the role of protein kinase C.

OBJECTIVES: This study examined the effect of a new specific Na(+)-H+ exchange inhibitor, Hoe 642, on infarct size and the protective role of protein kinase C (PKC) by this agent. In addition, we assessed the possible alteration of Hoe 642-induced cardioprotection by commonly used animal anesthetic drugs. BACKGROUND: Earlier studies on the contribution of Na(+)-H+ exchange to ischemic injury were complicated by nonspecific actions of the Na(+)-H+ exchange inhibitors, and the role of this exchanger in myocardial infarction in vivo remains unclear. The difference in anesthetic agents used in experiments could have resulted in discrepant findings regarding cardioprotection of some interventions, such as preconditioning and adenosine triphosphate-sensitive potassium channel openers. METHODS: Infarction was induced by 30 min of coronary occlusion and 3 h of reperfusion in the rabbit heart. In the first series of experiments, rabbits were anesthetized with pentobarbital or ketamine/xylazine. Hoe 642 was injected intravenously 10 min before ischemia or 5 min before reperfusion. In the second series of experiments, rabbits received 25 mg/kg body weight of polymyxin B (polyB), Hoe 642 plus polyB, preconditioning with 5 min of ischemia and 5 min of reperfusion plus polyB or preconditioning alone before 30 min of ischemia. RESULTS: In pentobarbital-anesthetized rabbits, 0.3 mg/kg and 0.6 mg/kg of Hoe 642 given before ischemia limited infarct size (as percent area at risk [%IS/AR]) to 42.7 +/- 4.4% (SEM) and 26.2 +/- 5.4%, respectively, from the control value of 55.1 +/- 3.5%. However, injection of Hoe 642 before reperfusion did not change infarct size (%IS/AR 49.6 +/- 4.9%, p = 0.387; power 0.81 for detecting 50% reduction). Infarct size limitation by the preischemic treatment with Hoe 642 was similarly observed in the rabbits anesthetized with ketamine/xylazine. In the polyB-treated rabbits, 0.6 mg/kg of Hoe 642 significantly limited infarct size (%IS/AR was 28.3 +/- 3.8% with Hoe 642 and 50.1 +/- 7.5% without Hoe 642), although preconditioning was blocked by the same dose of polyB (%IS/AR was 39.3 +/- 6.1% with polyB and 11.3 +/- 2.4% without polyB). CONCLUSIONS: Hoe 642 enhanced myocardial tolerance against infarction, and this enhanced tolerance was not influenced by anesthetic agents commonly used for infarct size studies. Infarct size limitation by Hoe 642 was not inhibited by polyB, suggesting that cardioprotection by Na(+)-H+ exchange inhibition is not PKC mediated and thus may be unrelated to preconditioning.

Roles of mitochondrial ATP-sensitive K channels and PKC in anti-infarct tolerance afforded by adenosine A1 receptor activation.

OBJECTIVES: This study intended to assess the role of mitochondrial ATP-sensitive potassium (mitoK ATP) channels and the sequence of signal transduction with protein kinase C (PKC) and adenosine A1 receptors in rabbits. BACKGROUND: To our knowledge, the link between trigger receptors of preconditioning, PKC and mitoK ATP channels has not been examined in a whole heart model of infarction. METHODS: In the first series of experiments, myocardial infarction was induced in isolated buffer-perfused rabbit hearts by 30-min global ischemia and 2-h reperfusion. Infarct size in the left ventricle was determined by tetrazolium staining and expressed as a percentage of area at risk (i.e., the whole left ventricle) (%IS/AR). In the second series of experiments, mitochondria were isolated from the heart, and their respiratory function was examined using glutamate as a substrate. RESULTS: Pretreatment with R-phenylisopropyladenosine (R-PIA, 1 micromol/liter), an A1-receptor agonist, reduced %IS/AR from 49.8 +/- 6.5% to 13.4 +/- 2.9%. This protection was abolished by calphostin C, a PKC inhibitor, and by 5-hydroxydecanoate (5-HD), a selective inhibitor of mitoK ATP channels. A selective mitoK ATP channel opener, diazoxide (100 micromol/liter), mimicked the effect of R-PIA on infarct size (%IS/AR = 11.6 +/- 4.0%), and this protective effect was also abolished by 5-HD. However, calphostin C failed to block the infarct size-limiting effect of diazoxide. Neither calphostin C nor 5-HD alone modified %IS/AR. State III respiration (QO2) and respiratory control index (RCI) were reduced after 30 min of ischemia (QO2 = 147.3 +/- 5.3 vs. 108.5 +/- 12.3, RCI = 22.3 +/- 1.1 vs. 12.1 +/- 1.8, p < 0.05). This mitochondrial dysfunction was persistent after 10 min of reperfusion (QO2 = 96.1 +/- 15.5, RCI = 9.5 +/- 1.9). Diazoxide significantly attenuated the respiratory dysfunction after 30 min of ischemia (QO2 = 142.8 +/- 9.7, RCI = 16.2 +/- 0.8) and subsequent 10-min reperfusion (QO2 = 135.3 +/- 7.2, RCI = 19.1 +/- 0.8). CONCLUSIONS: These results suggest that mitoK ATP channels are downstream of PKC in the mechanism of infarct-size limitation by A1-receptor activation and that the anti-infarct tolerance afforded by opening of mitoK ATP channels is associated with preservation of mitochondrial function during ischemia/reperfusion.

Captopril potentiates the myocardial infarct size-limiting effect of ischemic preconditioning through bradykinin B2 receptor activation.

OBJECTIVES: To investigate the role of kinin in preconditioning against infarction, the present study assessed the effect of captopril, a kininase II inhibitor, on preconditioning and arterial plasma kinin levels. BACKGROUND: Recent studies suggest a possible contribution of kinin to preconditioning against infarction. However, its role and the site of kinin production remain uncharacterized. METHODS: Six groups of rabbits (n = 6 to 13) underwent 30-min coronary occlusion and 3-h reperfusion. The infarct size and area at risk were determined by tetrazolium staining and fluorescent particles, respectively. Arterial blood was sampled under baseline conditions, before the 30-min ischemia and after reperfusion for radioimmunoassay of the kinin level. RESULTS: Infarct size expressed as a percentage of area at risk (%IS/AR) was 42.9 +/- 2.9% (mean +/- SEM) in the control group, 34.5 +/- 3.3% in the group preconditioned with 2 min of ischemia/5 min of reperfusion and 41.7 +/- 5.1% in the group given captopril (1 mg/kg body weight) alone before the 30-min ischemia. These %IS/AR values were not significantly different between the three groups. However, a combination of captopril and subsequent preconditioning with 2 min of ischemia markedly limited %IS/AR to 21.2 +/- 2.4%. This potentiation of 2 min of preconditioning by captopril was not observed when 2 micrograms/kg body weight of Hoe 140, a specific bradykinin B2 receptor antagonist, was administered before preconditioning (%IS/AR = 41.2 +/- 5.7%), whereas Hoe 140 alone did not modify infarct size (%IS/AR = 38.5 +/- 5.1%). Arterial plasma kinin levels were comparable between the control rabbits, the group given captopril alone and the group that received captopril plus 2 min of preconditioning at baseline (3.8 +/- 1.0, 6.3 +/- 1.9 and 5.2 +/- 1.7 pg/ml, respectively), and there was no significant change in kinin levels after the captopril injection or the combination of captopril plus 2 min of preconditioning. CONCLUSIONS: The present results indicate that captopril is capable of potentiating preconditioning without increasing the arterial kinin level and that the beneficial effect of captopril can be inhibited by Hoe 140. These findings support the hypothesis that kinin produced locally in the heart during preconditioning may contribute to the cardioprotective mechanism through bradykinin receptor activation.

Mitochondrial ATP-sensitive K+ channels play a role in cardioprotection by Na+-H+ exchange inhibition against ischemia/reperfusion injury.

OBJECTIVES: The possible role of the ATP-sensitive potassium (KATP) channel in cardioprotection by Na+-H+ exchange (NHE) inhibition was examined. BACKGROUND: The KATP channel is suggested to be involved not only in ischemic preconditioning but also in some pharmacological cardioprotection. METHODS: Infarction was induced by 30-min coronary occlusion in rabbit hearts in situ or by 30-min global ischemia in isolated hearts. Myocardial stunning was induced by five episodes of 5-min ischemia/5-min reperfusion in situ. In these models, the effects of NHE inhibitors (cariporide and ethylisopropyl-amiloride [EIPA]) and the changes caused by KATP channel blockers were assessed. In another series of experiments, the effects of EIPA on mitochondrial KATP (mito-KATP) and sarcolemmal KATP (sarc-KATP) channels were examined in isolated cardiomyocvtes. RESULTS: Cariporide (0.6 mg/kg) reduced infarct size in situ by 40%, and this effect was abolished by glibenclamide (0.3 mg/kg), a nonselective KATP channel blocker. In vitro, 1 microM cariporide limited infarct size by 90%, and this effect was blocked by 5-hydroxydecanoate (5-HD), a mito-KATP channel blocker but not by HMR1098, a sarc-KATP channel blocker. Infarct size limitation by 1 microM EIPA was also prevented by 5-HD. Cariporide attenuated regional contractile dysfunction by stunning, and this protection was abolished by glibenclamide and 5-HD. Ethylisopropyl amiloride neither activated the mito-KATP channel nor enhanced activation of this channel by diazoxide, a KATP channel opener. CONCLUSIONS: Opening of the mito-KATP channel contributes to cardioprotection by NHE inhibition, though the interaction between NHE and this KATP channel remains unclear.

Developmental and Hormonal Regulation of Rice [alpha]-Amylase(RAmy1A)-gusA Fusion Genes in Transgenic Rice Seeds.

Transgenic seeds of rice (Oryza sativa L.) were used to investigate temporal, spatial, and hormonal regulation of a rice [alpha]-amylase gene, RAmy1A. Two overlapping segments of the RAmy1A promoter were fused to the coding region of the bacterial reporter gene, gusA. The resulting promoter-gusA fusions, pE4/GUS (-232 to +31) and pH4/GUS (-748 to +31), were used separately to transform rice protoplasts. [beta]-Glucuronidase (GUS) activity was detected in germinated transgenic seeds, although the two constructs showed no significant difference in timing or location of GUS expression. Both constructs first expressed GUS in the scutellar epithelium and then in the aleurone layer. Aleurone expression of GUS activity was strongly induced when embryoless half-seeds were treated with gibberellic acid. GUS expression in the aleurone layer was also suppressed by abscisic acid. These results indicate that the 5[prime] regulatory region from -232 to +31 is sufficient for temporal, spatial, and hormonal regulation of RAmy1A gene expression.

Does Decrease in Ribulose-1,5-Bisphosphate Carboxylase by Antisense RbcS Lead to a Higher N-Use Efficiency of Photosynthesis under Conditions of Saturating CO2 and Light in Rice Plants?

Rice (Oryza sativa L.) plants with decreased ribulose-1,5-bisphosphate carboxylase (Rubisco) were obtained by transformation with the rice rbcS antisense gene under the control of the rice rbcS promoter. The primary transformants were screened for the Rubisco to leaf N ratio, and the transformant with 65% wild-type Rubisco was selected as a plant set with optimal Rubisco content at saturating CO2 partial pressures for photosynthesis under conditions of high irradiance and 25[deg]C. This optimal Rubisco content was estimated from the amounts and kinetic constants of Rubisco and the gas-exchange data. The R1 selfed progeny of the selected transformant were grown hydroponically with different N concentrations. Rubisco content in the R1 population was distributed into two groups: 56 plants had about 65% wild-type Rubisco, whereas 23 plants were very similar to the wild type. Although the plants with decreased Rubisco showed 20% lower rates of light-saturated photosynthesis in normal air (36 Pa CO2), they had 5 to 15% higher rates of photosynthesis in elevated partial pressures of CO2, (100-115 Pa CO2) than the wild-type plants for a given leaf N content. We conclude that the rice plants with 65% wild-type Rubisco show a higher N-use efficiency of photosynthesis under conditions of saturating CO2 and high irradiance.