Stimulation of the sigma-1 receptor by DHEA enhances synaptic efficacy and neurogenesis in the hippocampal dentate gyrus of olfactory bulbectomized mice

Dehydroepiandrosterone (DHEA) is the most abundant neurosteroid synthesized de novo in the central nervous system. We previously reported that stimulation of the sigma-1 receptor by DHEA improves cognitive function by activating calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase C and extracellular signal-regulated kinase in the hippocampus in olfactory bulbectomized (OBX) mice. Here, we asked whether DHEA enhances neurogenesis in the subgranular zone of the hippocampal dentate gyrus (DG) and improves depressive-like behaviors observed in OBX mice. Chronic treatment with DHEA at 30 or 60 mg/kg p.o. for 14 days significantly improved hippocampal LTP impaired in OBX mice concomitant with increased CaMKII autophosphorylation and GluR1 (Ser-831) phosphorylation in the DG. Chronic DHEA treatment also ameliorated depressive-like behaviors in OBX mice, as assessed by tail suspension and forced swim tests, while a single DHEA treatment had no affect. DHEA treatment also significantly increased the number of BrdU-positive neurons in the subgranular zone of the DG of OBX mice, an increase inhibited by treatment with NE-100, a sigma-1 receptor antagonist. DHEA treatment also significantly increased phosphorylation of Akt (Ser-473), Akt (Ser-308) and ERK in the DG. Furthermore, GSK-3β (Ser-9) phosphorylation increased in the DG of OBX mice possibly accounting for increased neurogenesis through Akt activation. Finally, we confirmed that DHEA treatment of OBX mice increases the number of BrdU-positive neurons co-expressing β-catenin, a downstream GSK-3βtarget. Overall, we conclude that sigma-1 receptor stimulation by DHEA ameliorates OBX-induced depressive-like behaviors by increasing neurogenesis in the DG through activation of the Akt/GSK-3β/β-catenin pathway.

Crucial interactions between selective serotonin uptake inhibitors and sigma-1 receptor in heart failure

Depression is associated with a substantial increase in the risk of developing heart failure and is independently associated with increased cardiovascular morbidity and mortality. Inversely, cardiovascular disease can lead to severe depression. Thus, therapy with selective serotonin reuptake inhibitors (SSRIs) is strongly recommended to reduce cardiovascular disease-induced morbidity and mortality. However, molecular mechanisms to support evidence-based SSRI treatment of cardiovascular disease have not been elucidated. We recently found very high expression of the sigma-1 receptor, an orphan receptor, in rat heart tissue and defined the cardiac sigma-1 receptor as a direct SSRI target in eliciting cardioprotection in both pressure overload (PO)induced and transverse aortic constriction (TAC)-induced myocardial hypertrophy models in rodents. Our findings suggest that SSRIs such as fluvoxamine protect against PO- and TAC-induced cardiac dysfunction by upregulating sigma-1 receptor expression and stimulating sigma-1 receptor-mediated Akt-eNOS signaling. Here, we discuss the association of depression and cardiovascular diseases, the protective mechanism of SSRIs in heart failure patients, and the pathophysiological relevance of sigma-1 receptors to progression of heart failure. These findings should promote development of clinical therapeutics targeting the sigma-1 receptor in cardiovascular diseases.

Stimulation of σ1-receptor restores abnormal mitochondrial Ca²⁺ mobilization and ATP production following cardiac hypertrophy

BACKGROUND

We previously reported that the σ1-receptor (σ1R) is down-regulated following cardiac hypertrophy and dysfunction in transverse aortic constriction (TAC) mice. Here we address how σ1R stimulation with the selective σ1R agonist SA4503 restores hypertrophy-induced cardiac dysfunction through σ1R localized in the sarcoplasmic reticulum (SR).

METHODS

We first confirmed anti-hypertrophic effects of SA4503 (0.1-1μM) in cultured cardiomyocytes exposed to angiotensin II (Ang II). Then, to confirm the ameliorative effects of σ1R stimulation in vivo, we administered SA4503 (1.0mg/kg) and the σ1R antagonist NE-100 (1.0mg/kg) orally to TAC mice for 4weeks (once daily).

RESULTS

σ1R stimulation with SA4503 significantly inhibited Ang II-induced cardiomyocyte hypertrophy. Ang II exposure for 72h impaired phenylephrine (PE)-induced Ca(2+) mobilization from the SR into both the cytosol and mitochondria. Treatment of cardiomyocytes with SA4503 largely restored PE-induced Ca(2+) mobilization into mitochondria. Exposure of cardiomyocytes to Ang II for 72h decreased basal ATP content and PE-induced ATP production concomitant with reduced mitochondrial size, while SA4503 treatment completely restored ATP production and mitochondrial size. Pretreatment with NE-100 or siRNA abolished these effects. Chronic SA4503 administration also significantly attenuated myocardial hypertrophy and restored ATP production in TAC mice. SA4503 administration also decreased hypertrophy-induced impairments in LV contractile function.

CONCLUSIONS

σ1R stimulation with the specific agonist SA4503 ameliorates cardiac hypertrophy and dysfunction by restoring both mitochondrial Ca(2+) mobilization and ATP production via σ1R stimulation.

GENERAL SIGNIFICANCE

Our observations suggest that σ1R stimulation represents a new therapeutic strategy to rescue the heart from hypertrophic dysfunction.

Abstract 249: Sigma-1 Receptor Agonist Ameliorates Mitochondrial ATP Production and Apoptosis in Cardiac Myocytes

Objective: Selective serotonin reuptake inhibitors (SSRIs) are known to reduce post-myocardial infarction (MI)-induced morbidity and mortality. However, the molecular mechanism underlying SSRI-induced cardioprotection remains unclear. We previous reported that fluvoxamine with high affinity for sigma-1 receptor ameliorates cardiac hypertrophy and dysfunction via sigma-1 receptor stimulation. In non-cardiomyocytes, sigma-1 receptor interacts with IP 3 receptor (IP 3 R), which may promote Ca 2+ transport to mitochondria. We here investigated the role of sigma-1 receptor for sarcoplasmic reticulum (SR)-mitochondrial Ca 2+ signaling in neonatal rat ventricular cardiomyocytes.

Methods: Cultured cardiomyocytes were treated with angiotensin II (Ang II) during 72 hr followed by fluvoxamine and/or NE-100 treatment during the last 24 hr. Then, we investigated intracellular localization of sigma-1 receptor and IP 3 R. We also measured phenylephrine (PE)-induced mitochondrial Ca 2+ and cytosolic Ca 2+ mobilization and ATP content in Ang II-treated cardiomyocytes with or without fluvoxamine treatments.

Results: Ang II stimulation for 72 hr elicited cardiomyocyte hypertrophy, downregulation of sigma-1 receptor expression and declined PE-induced Ca 2+ mobilization into cytosol and mitochondria. Fluvoxamine treatments restored sigma-1 receptor expression and PE-induced Ca 2+ mobilization into mitochondria. Moreover, fluvoxamine treatment completely restored Ang II-induced apoptosis. We also confirmed in vivo that fluvoxamine treatment rescue transverse aortic constriction-induced cardiac dysfunction and the reduced ATP concentration.

Conclusions: These results suggested that fluvoxamine rescue cardiomyocytes from AngII-induced cardiac myocyte apoptosis through enhancement of SR-mitochondria Ca 2+ transport and mitochondrial ATP production via sigma-1 receptor stimulation.

Abstract 4: The Mitochondrial Ca 2+ Transport and ATP Production Through Sigma-1 Receptor in Heart

Objective: Although sigma-1 receptor is originally postulated as an opioid receptor in the central nervous system, we recently defined the higher expression of sigma-1 receptor in cardiac ventricle and kidney as compared to brain tissues (Expert Opin Ther Targets 2010;14:1009-1022). To address the question whether mitochondrial Ca 2+ transport and ATP production in heart are regulated by sigma-1 receptor stimulation, we tested the anti-hypertrophic effects of the specific sigma-1 receptor agonist, SA4503 in transverse aortic constriction (TAC) mice.

Methods: We treated mice with SA4503 (0.1, 0.3 and 1.0 mg/kg) orally once a day for 4 weeks after TAC. The cardiac constriction was monitored by echocardiography. The mitochondrial Ca 2+ transport and ATP production with or without SA4503 treatment were measured in cultured neonatal cardiomyocytes.

Results: The sigma-1 receptor expression in the left ventricle (LV) decreased significantly over the 4 weeks. SA4503 administration significantly attenuated TAC-induced myocardial hypertrophy concomitant with the recovery of sigma-1 receptor expression in LV. SA4503 also ameliorated the impaired LV fractional shortening. We also investigated the role of sigma-1 receptor for sarcoplasmic reticulum (SR)-mitochondrial Ca 2+ transport in cultured neonatal rat ventricular cardiomyocytes. Exposure to angiotensin II (Ang II) for 72 hr elicited marked cardiomyocyte hypertrophy and declined phenylephrine (PE)-induced Ca 2+ mobilization into cytosol and mitochondria. SA4503 treatment restored significantly the reduced PE-induced Ca 2+ mobilization into mitochondria. Importantly, The Ang II-induced hypertrophy in vitro and transverse aortic constriction-induced cardiac dysfunction in vivo were associated with the reduced ATP concentration, which was completely restored by SA4503 treatment. NE-100, a sigma-1 receptor selective antagonist, abolished these effects induced by SA4503.

Conclusion: The specific sigma-1 receptor agonist, SA4503 ameliorates AngII-induced cardiomyocyte hypertrophy and TAC-induced cardiac dysfunction through restoration of SR-mitochondria Ca 2+ transport via sigma-1 receptor stimulation, thereby promoting mitochondrial ATP production.

Expression of a truncated form of the endoplasmic reticulum chaperone protein, σ1 receptor, promotes mitochondrial energy depletion and apoptosis

The σ1 receptor (σ(1)R) regulates endoplasmic reticulum (ER)/mitochondrial interorganellar Ca(2+) mobilization through the inositol 1,4,5-trisphosphate receptor (IP(3)R). Here, we observed that expression of a novel splice variant of σ(1)R, termed short form σ(1)R (σ(1)SR), has a detrimental effect on mitochondrial energy production and cell survival. σ(1)SR mRNA lacks 47 ribonucleotides encoding exon 2, resulting in a frameshift and formation of a truncated receptor. σ(1)SR localizes primarily in the ER at perinuclear regions and forms a complex with σ(1)R but not with IP(3)R in the mitochondrion-associated ER membrane. Overexpression of both σ(1)R and the truncated isoform promotes mitochondrial elongation with increased ER mitochondrial contact surface. σ(1)R overexpression increases the efficiency of mitochondrial Ca(2+) uptake in response to IP(3)R-driven stimuli, whereas σ(1)SR overexpression reduces it. Most importantly, σ(1)R promotes ATP production via increased mitochondrial Ca(2+) uptake, promoting cell survival in the presence of ER stress. By contrast, σ(1)SR suppresses ATP production following ER stress, enhancing cell death. Taken together, the newly identified σ(1)SR isoform interferes with σ(1)R function relevant to mitochondrial energy production under ER stress conditions, promoting cellular apoptosis.

[Cardioprotective effect of fluvoxamine, sigma-1 receptor high affinity agonist]

Selective serotonin reuptake inhibitors (SSRIs) are known to reduce post-myocardial infarction (MI)-induced morbidity and mortality. However, the molecular mechanism underlying SSRI-induced cardioprotection remains unclear. Here, we investigated the role of sigma-1 receptor (Sig-1R) stimulation with fluvoxamine on myocardial hypertrophy and cardioprotection. Male ICR mice were subjected to transverse aortic constriction (TAC) in the cardiac aortic arch. To confirm the cardioprotective role of Sig-1R stimulation by fluvoxamine, we treated mice with fluvoxamine (0.5 or 1 mg/kg) orally once a day for 4 weeks after onset of aortic banding. Interestingly, in untreated mice, Sig-1R expression in the left ventricle (LV) markedly decreased over 4 weeks with increased hypertrophy. By contrast, fluvoxamine administration significantly attenuated TAC-induced myocardial hypertrophy concomitant with recovery of Sig-1R expression in LV. Fluvoxamine also attenuated hypertrophy-induced impaired LV fractional shortening. The fluvoxamine cardioprotective effect was nullified by treatment with a Sig-1R antagonist, NE-100 (1 mg/kg). Importantly, another SSRI with very low affinity for Sig-1R, paroxetine, did not exhibit antihypertrophic effects in TAC mice and in cultured cardiomyocyte treated with angiotensin II. Fluvoxamine treatment significantly restored TAC-induced impaired Akt and eNOS phosphorylation in LV. Our findings suggest that fluvoxamine protects heart against TAC-induced cardiac dysfunction via upregulation of Sig-1R and stimulation of Sig-1R-mediated Akt-eNOS signaling in mice. This is the first report of a potential role of Sig-1R stimulation by fluvoxamine in preventing cardiac hypertrophy and myocardial injury in TAC mice.

Abstract P229: Nongenomic Cardioprotective Effect of Dehydroepiandrosterone on Cardiac Hypertrophy: Comparison with 17β-Estradiol-Induced Cardioprotection

Objective: We recently reported a decreased σ 1 receptor expression in heart following abdominal aortic stenosis in bilateral ovariectomized (OVX) rats. Here, we demonstrated non-genemic cardioprotective effects of dehydroepiandrosterone (DHEA) though σ1 receptor in pressure overload (PO)-induced cardiac dysfunction.

Methods: Bilateral ovariectomy was performed in female rats. Two weeks after the sham operation or ovariectomy, pressure-overload was initiated by abdominal aortic banding. 17β-estradiol (E2: 0.1 mg/kg) and DHEA (30 mg/kg) were administered to rats subcutaneously and orally, respectively, for 14 days starting 2 weeks after aortic banding. Hemodynamic parameters and cardiac hypertrophy were measured after 2 weeks of drug treatment. After dissection out of left ventricular, gene expression and hypertrophic signaling were analyzed by real-time RT-PCR and western blot, respectively.

Results: Both E2 and DHEA treatments significantly inhibited pressure overload-induced increases both in heart weight/body weight (HW/BW) ratio and lung weight/body weight (LW/BW) ratios. Both E2 and DHEA treatments also ameliorated hypertrophy-induced impairment of left ventricular end diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), left ventricular contraction and relaxation (±dp/dt) rates, heart rate (HR) and mean arterial blood pressure (MABP). Notably, DHEA but not E2 administration rescued PO-induced σ 1 receptor downregulation in left ventricular. Co-administration with NE-100, a σ 1 receptor selective antagonist, inhibited DHEA-induced amelioration of heart dysfunction without effects on E2-induced cardioprotection. Mechanistically, both E2 and DHEA treatments significantly restored PO-induced decreases in Akt phosphorylation and Akt-mediated eNOS phosphorylation (Ser1179). NE-100 treatment totally abolished DHEA-induced Akt and eNOS phosphorylation without effects on E2-induced Akt/eNOS activation.

Conclusions: Taken together, based on these results with OVX rat heart, DHEA but not E2 elicits cardioprotective action through σ 1 receptor activation. DHEA-induced Akt/eNOS activation through σ 1 receptors likely mediates the cardioprotective activity.

Distinct cardioprotective effects of 17β-estradiol and dehydroepiandrosterone on pressure overload-induced hypertrophy in ovariectomized female rats

OBJECTIVE

We recently reported decreased σ1 receptor expression in the heart after abdominal aortic stenosis in bilateral ovariectomized rats. Here, we use ovariectomized female rats to investigate the distinct cardioprotective effects of 17β-estradiol (E2) and dehydroepiandrosterone (DHEA) in pressure overload (PO)-induced cardiac dysfunction.

METHODS

E2 (0.1 mg/kg) and DHEA (30 mg/kg) were administered to rats subcutaneously and orally, respectively, for 14 days starting 2 weeks after aortic banding.

RESULTS

Both E2 and DHEA treatments significantly inhibited PO-induced increases both in heart weight/body weight ratio and lung weight/body weight ratios. Both E2 and DHEA also ameliorated hypertrophy-induced impairment of left ventricular end-diastolic pressure, left ventricular-developed pressure, left ventricular contraction and relaxation (± dp/dt) rates, heart rate, and mean arterial blood pressure. Notably, DHEA but not E2 administration rescued decreased PO-induced σ1 receptor reduction in the heart. Coadministration with N,N-Dipropyl-2-[4-methoxy-3-(2-phenylethoxy) phenyl]-ethylamine monohydrochloride, an σ1 receptor antagonist, inhibited DHEA-induced amelioration of heart dysfunction without altering E2-induced cardioprotection. Mechanistically, both E2 and DHEA treatments significantly restored PO-induced decreases in protein kinase B (Akt) phosphorylation and Akt-mediated endothelial nitric oxide synthase (eNOS) phosphorylation (Ser1179). N,N-Dipropyl-2-[4-methoxy-3-(2-phenylethoxy) phenyl]-ethylamine monohydrochloride treatment totally abolished DHEA-induced Akt and eNOS phosphorylation without altering E2-induced Akt-eNOS activation.

CONCLUSIONS

Taken together, these results from an ovariectomized rat model of PO-induced cardiac dysfunction show that DHEA but not E2 elicits a cardioprotective action through σ1 receptor activation. DHEA-induced Akt-eNOS activation through σ1 receptors is probably associated with its cardioprotective activity.

Dehydroepiandrosterone-mediated stimulation of sigma-1 receptor activates Akt-eNOS signaling in the thoracic aorta of ovariectomized rats with abdominal aortic banding

OBJECTIVE

Decreased dehydroepiandrosterone (DHEA) levels are associated with endothelial dysfunction and increased cardiovascular mortality in postmenopausal women. Using ovariectomized rats, we first defined whether expression of sigma-1 receptor (Sig-1R) in the aorta is regulated following pressure overload (PO) and also after DHEA treatment. We also investigated effects of DHEA known as Sig-1R agonist on impaired Akt/endothelial nitric oxide synthase (eNOS) signaling in the thoracic aorta under PO.

RESEARCH DESIGN/METHODS

Wistar rats subjected to bilateral ovariectomy (OVX) were further treated with abdominal aortic stenosis 2 weeks later. DHEA (15 and 30 mg/kg) was administered orally once a day for 14 days starting from 2 weeks after the aortic banding.

RESULTS

Time course study indicated that expression of Sig-1R expression and eNOS decreased time dependently in the thoracic aorta from 1 to 4 weeks after PO. DHEA treatment significantly inhibited the decreased Sig-1R expression in the thoracic aorta. The DHEA treatment also significantly restored PO-induced impaired Akt phosphorylation and stimulated eNOS protein expression with concomitant increased Akt-mediated eNOS phosphorylation (Ser1177). We did not find any changes in the phosphorylation of ERK1/2 and PKCα in the aorta following PO and after treatment with DHEA.

CONCLUSION

We here reported, for the first time, that DHEA treatment induces the upregulation and stimulation of Sig-1R in the thoracic aorta that stimulate Sig-1R-mediated Akt-eNOS signaling pathways in ovariectomized rats under PO.

Sigma-1 receptor stimulation with fluvoxamine activates Akt-eNOS signaling in the thoracic aorta of ovariectomized rats with abdominal aortic banding

In the present study, we investigated the vasculoprotective effect of sigma-1 receptor stimulation with fluvoxamine on pressure overload hypertrophy-induced vascular injury in the thoracic aorta and defined mechanisms underlying that activity. Wistar rats underwent bilateral ovariectomy, and two weeks later were further treated with abdominal aortic stenosis. To confirm the vasculoprotective role of sigma-1 receptor signaling, we treated rats with the agonist fluvoxamine (at 0.5 and 1.0 mg/kg) and with the antagonist NE-100 (at 1.0mg/kg) for 4 weeks orally once a day after the onset of aortic banding. Interestingly, sigma-1 receptor expression in the thoracic aorta decreased significantly 4 weeks after pressure overload-induced hypertrophy in vehicle treated ovariectomized rats. Fluvoxamine administration significantly attenuated pressure overload-induced vascular injury with concomitant increase in receptor expression and subsequent decrease in IP3 receptor expression. Fluvoxamine treatment also significantly restored pressure overload-induced impaired Akt phosphorylation and stimulated eNOS protein expression as well as Akt-mediated eNOS phosphorylation (Ser1177). Fluvoxamine's vasculoprotective effect was nullified by co-administration of a sigma-1 receptor antagonist. No changes in phosphorylation of ERK1/2 or PKCα in the aorta were observed following pressure overload and after fluvoxamine treatment. Our findings confirm, for the first time, a potential role for sigma-1 receptor expression and signaling in the thoracic aorta in attenuating hypertrophy-induced vascular injury in ovariectomized rats. Thus, we demonstrate, for the first time, a potential role in the thoracic aorta for sigma-1 receptor expression and signaling via Akt-eNOS in attenuating hypertrophy-induced vascular injury in ovariectomized rats.

Sigma1-receptor stimulation with fluvoxamine ameliorates transverse aortic constriction-induced myocardial hypertrophy and dysfunction in mice

Selective serotonin reuptake inhibitors (SSRIs) are known to reduce post-myocardial infarction-induced morbidity and mortality. However, the molecular mechanism underlying SSRI-induced cardioprotection remains unclear. Here, we investigated the role of σ(1)-receptor (σ(1)R) stimulation with fluvoxamine on myocardial hypertrophy and cardiac functional recovery. Male ICR mice were subjected to transverse aortic constriction (TAC) in the cardiac aortic arch. To confirm the cardioprotective role of fluvoxamine by σ(1)R stimulation, we treated mice with fluvoxamine (0.5 or 1 mg/kg) orally once per day for 4 wk after the onset of aortic banding. Interestingly, in untreated mice, σ(1)R expression in the left ventricle (LV) decreased significantly over the 4 wk as TAC-induced hypertrophy increased. In contrast, fluvoxamine administration significantly attenuated TAC-induced myocardial hypertrophy concomitant with recovery of σ(1)R expression in the LV. Fluvoxamine also attenuated hypertrophy-induced impaired LV fractional shortening. The fluvoxamine cardioprotective effect was nullified by treatment with a σ(1)R antagonist [NE-100 (1 mg/kg)]. Importantly, another SSRI with very low affinity for σ(1)Rs, paroxetine, did not elicit antihypertrophic effects in TAC mice and cultured cardiomyocytes. Fluvoxamine treatment significantly restored TAC-induced impaired Akt and endothelial nitric oxide synthase (eNOS) phosphorylation in the LV. Our findings suggest that fluvoxamine protects against TAC-induced cardiac dysfunction via upregulated σ(1)R expression and stimulation of σ(1)R-mediated Akt-eNOS signaling in mice. This is the first report of a potential role for σ(1)R stimulation by fluvoxamine in attenuating cardiac hypertrophy and restoring contractility in TAC mice.

Targeting sigma-1 receptor with fluvoxamine ameliorates pressure-overload-induced hypertrophy and dysfunctions

OBJECTIVE

We here investigated the effect of sigma-1 receptor (Sig-1R) stimulation with fluvoxamine on myocardial hypertrophy, cardiac functional recovery and defined mechanisms underlying its cardioprotective action.

METHODS

Wistar rats subjected to bilateral ovariectomy (OVX) were treated with abdominal aortic banding between the right and left renal arteries. To confirm the cardioprotective role of Sig-1R stimulation, we treated the rats with Sig-1R agonist (fluvoxamine, 0.5 and 1 mg/kg) orally once a day for 4 weeks after the onset of aortic banding.

RESULTS

Interestingly, the expression of Sig-1R in the left ventricle (LV) decreased significantly 4 weeks after pressure overload (PO)-induced hypertrophy in OVX rats. The fluvoxamine administration significantly attenuated PO-induced myocardial hypertrophy with concomitant increase in the expression of Sig-1R in LV. Fluvoxamine also attenuated hypertrophy-induced impaired LV functions. The cardioprotective effect of fluvoxamine was nullified by treatment with Sig-1R antagonist (NE-100; 1 mg/kg). Fluvoxamine treatment significantly restored PO-induced impaired eNOS and Akt activity in the LV.

CONCLUSION

We here found, for the first time, the potential role of Sig-1R expression in the heart in attenuating PO-induced hypertrophy in OVX rats. Fluvoxamine treatment protects PO-induced cardiac injury via upregulation of Sig-1R and stimulation of Sig-1R-mediated Akt-eNOS signaling in ovariectomized rats.

Comparison of the quality of temporal subtraction images obtained with manual and automated methods of digital chest radiography

The authors have been developing a fully automated temporal subtraction scheme to assist radiologists in the detection of interval changes in digital chest radiographs. The temporal subtraction image is obtained by subtraction of a previous image from a current image. The authors' automated method includes not only image shift and rotation techniques but also a nonlinear geometric warping technique for reduction of misregistration artifacts in the subtraction image. However, a manual subtraction method that can be carried out only with image shift and rotation has been employed as a common clinical technique in angiography, and it might be clinically acceptable for detection of interval changes on chest radiographs as well. Therefore, the authors applied both the manual and automated temporal subtraction techniques to 181 digital chest radiographs, and compared the quality of the subtraction images obtained with the two methods. The numbers of clinically acceptable subtraction images were 147 (81.2%) and 176 (97.2%) for the manual and automated subtraction methods, respectively. The image quality of 148 (81.8%) subtraction images was improved by use of the automated method in comparison with the subtraction images obtained with the manual method. These results indicate that the automated method with the nonlinear warping technique can significantly reduce misregistration artifacts in comparison with the manual method. Therefore, the authors believe that the automated subtraction method is more useful for the detection of interval changes in digital chest radiographs.

[A case of local recurrence of rectal cancer responding to local intraarterial infusion therapy]

A 42-year-old male developed pain in the right gluteal region due to local recurrence after curative resection of advanced lower rectal cancer. Radiotherapy (60 Gy) was performed, but satisfactory results were not obtained. Therefore, a reservoir was placed lowing cannulation of the internal iliac artery. The chemotherapy, in addition to intravenous administration of low dose CDDP (20 mg), included local intraarterial infusion therapy with 5-FU (1,500 mg/5 hour) once per week. After 10 courses of this chemotherapy (total dose: CDDP, 200 mg; 5-FU, 15,000 mg), the pain decreased, and the tumor size was reduced without side effects, improving the patient's QOL. At present, multidisciplinary treatments including such chemotherapy and radiotherapy is performed for local recurrence of rectal cancer, but adequate results are often not obtained. Local intraarterial infusion chemotherapy via the internal iliac artery accompanied by changes in blood flow can be safely performed on an outpatient basis, and appears to be effective for local recurrence of rectal cancer.

Suppression of electrophoretic anomaly of bent DNA segments by the structural property that causes rapid migration

Intrinsic DNA curvature is speculated to be a common feature of all satellite DNA sequences and may aid in the tight winding of DNA in constitutive heterochromatin. Several satellite DNAs, however, show unusually rapid migration in non-denaturing polyacrylamide gels, which is just the opposite behavior of that shown by curved DNA structures. Employing bovine satellite I DNA monomer, we attempted to understand the molecular mechanism of 'rapid migration'. The phenomenon of rapid migration was temperature-dependent and to a small extent polyacrylamide-concentration-dependent. Physiological or near-physiological concentrations of Mg2+and Ca2+ions bent the rapid migrating DNA segment. Predominance of purine-purine base stacking over purine-pyrimidine in nucleotide sequence was strongly indicated to be the cause of the rapid migration. Furthermore, they seemed to be implicated in the formation of induced DNA bend. We also found that the satellite I monomer contains an intrinsic DNA curvature as do many other satellites. Heretofore, the rapid migration property has concealed the presence of curvature.

Reduced metastatic potential and c-myc overexpression of colon adenocarcinoma cells (Colon 26 line) transfected with nm23-R2/rat nucleoside diphosphate kinase alpha isoform

Increased expression of nm23/nucleoside diphosphate kinase (NDP kinase) has been reported to be associated with both reduced metastatic potential in breast carcinoma and tumor progression in colon adenocarcinoma and lung adenocarcinoma. We examined effects of expression of nm23-R2 rat NDP kinase alpha isoform on mouse adenocarcinoma cells (Colon 26 line) and found a significant reduction of metastatic potential along with overexpression of c-myc. We also found that the proliferation rate of the transformed cells was the same as that of the control cells in culture. These results indicate that the cell growth potential in vitro is irrelevant to metastatic potential of the cells in vivo.

Characterization of DNA fragments that show anomalously rapid migration in non-denaturing polyacrylamide gels

Several DNA fragments that show anomalously rapid migration in nondenaturing polyacrylamide gels have been cloned from digests of bovine genomic DNA. Electrophoretic behaviors of these fragments were analyzed in detail under various conditions. The results indicated that these fragments may adopt non-B DNA conformation.

Modeling of a Micro-streamer Initiation and Development of ArF Excimer Laser Discharges

The dynamics of a constricted filamentary or ‘micro-streamer’ discharge in a discharge-excited ArF excimer laser has been examined using a two-dimensional fluid model. The entire process on a micro-streamer, from its initiation and development to extinction, is shown. In the present model, a micro-streamer is triggered at protrusions which always exist on cathode surfaces, and develops in the direction of the anode assisted by the high field induced by space charge. A rise in the gas temperature in the micro-streamer in the vicinity of a cathode is seen, and which is found to play an important role in its development. The effect of preionisation electron density ne0 on the streamer development is also examined, and the streamer is found to extend significantly when ne0 becomes low. The results are explained in connection with experimental observations.

Epidermal growth factor receptor in human hepatocellular carcinoma

To determine whether a relationship exists between expression of epidermal growth factor receptor (EGFR) and clinicopathological characteristics of hepatocellular carcinoma (HCC), EGFR was examined in 25 patients surgically treated for HCC using [125I]1-labeled EGF binding assay. Six cases were classified as stage I, 12 as stage II, 4 as stage III, and 3 as stage IV. Partial hepatectomy was performed in 11 cases, segmentectomy in 6, and lobectomy in 8. The level of EGFR in HCC was 8.9 (14.6) fmol/mg protein in HCC and 11.4 (9.2) fmol/mg protein in the adjacent noncancerous diseased liver tissues, and EGFR level in HCC was significantly lower than that of noncancerous liver tissues. HCC stage I + II had significantly lower levels of EGFR compared with stage III + IV (p < 0.05). Our study showed no obvious correlation between EGFR levels and other pathologic characteristics, such as tumor diameter, Edmondson's grade, extracapsular invasion, and vascular invasion. There was no significant difference in EGFR level between DNA diploid and aneuploid tumors. These results suggest that EGFR is not a relevant oncogenic factor for HCC.

Kinetic studies of cytochrome P-45017 alpha, lyase dependent androstenedione formation from progesterone

The reaction mechanism of androstenedione formation from progesterone was analyzed in a membrane reconstituted system consisting of P-45017 alpha, lyase and NADPH-cytochrome P-450 reductase using a rapid quenching device at 10 degrees C. In these rapid quenching experiments, only the metabolites of [3H]progesterone bound to P-45017 alpha, lyase at the initial stage were detectable during the limited cycles of the P-45017 alpha, lyase reactions (1-120 s). The level of 17 alpha-hydroxy[3H]progesterone increased rapidly in a short period (1-5 s) and then decreased to about half. That of [3H]androstenedione increased gradually from 2 s, which exactly corresponded to the decrease in 17 alpha-hydroxy[3H]progesterone. 17 alpha-Hydroxyprogesterone was conclusively the actual intermediate steroid which did not dissociate from P-45017 alpha, lyase during the successive hydroxylation reaction into androstenedione. A kinetic model can clearly describe the successive reaction catalyzed by P-450 17 alpha, lyase, in which progesterone is converted successively into androstenedione via 17 alpha-hydroxyprogesterone, some of which dissociates from the active site of P-450 17 alpha, lyase and is never metabolized into androstenedione. We analyzed the effects of pH and the amount of NADPH-cytochrome P-450 reductase on the successive reaction and proved that the reaction was regulated by the rate of electron transfer for the conversion of the bound 17 alpha-hydroxyprogesterone to androstenedione. Furthermore, we found that the product dissociation from P-450 17 alpha, lyase is the rate-limiting process in the steady-state metabolism of progesterone by P-450 17 alpha, lyase.

Changes in IL-6 and IL-8 after hepatectomy in patients with liver cirrhosis

Changes in tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) were investigated before and after hepatectomy in patients with or without liver cirrhosis (5 cases without liver cirrhosis and 14 cases with liver cirrhosis). Both the IL-6 and IL-8 values of the cirrhotic patients were significantly higher on the first postoperative day (POD) as compared with the non-cirrhotic patients. Overall, no significant correlation was found between peak values of IL-6 or IL-8 and blood loss or operating time. In the case of the cirrhotic patients, correlation of both IL-6 and IL-8 with operating time was significant at p < 0.05, gamma = 0.534 and 0.586, respectively. No correlation was found between blood loss and the peak value of IL-6, but significant correlation (gamma = 0.647, p < 0.05) was found between them in cirrhotic patients. There was no consistent increase in TNF-alpha and IL-1 beta following hepatectomy. These findings indicate that procedures undertaken to reduce the excessive production of these cytokines may be useful for preventing complications after hepatectomy in cirrhotic patients.