Reduced Neuroinflammation Via Astrocytes and Neutrophils Promotes Regeneration After Spinal Cord Injury in Neonatal Mice

Neonatal spinal cord injury (SCI) shows better functional outcomes than adult SCI. Although the regenerative capability in the neonatal spinal cord may have cues in the treatment of adult SCI, the mechanism underlying neonatal spinal cord regeneration after SCI is unclear. We previously reported age-dependent variation in the pathogenesis of inflammation after SCI. Therefore, we explored differences in the pathogenesis of inflammation after SCI between neonatal and adult mice and their effect on axon regeneration and functional outcome. We established two-day-old spinal cord crush mice as a model of neonatal SCI. Immunohistochemistry of the spinal cord revealed that the nuclear translocation of NF-κB, which promotes the expression of chemokines, was significantly lower in the astrocytes of neonates than in those of adults. Flow cytometry revealed that neonatal astrocytes secrete low levels of chemokines to recruit circulating neutrophils (e.g., Cxcl1 and Cxcl2) after SCI in comparison with adults. We also found that the expression of a chemokine receptor (CXCR2) and an adhesion molecule (β2 integrin) quantified by flow cytometry was lower in neonatal circulating neutrophils than in adult neutrophils. Strikingly, these neonate-specific cellular properties seemed to be associated with no neutrophil infiltration into the injured spinal cord, followed by significantly lower expression of inflammatory cytokines (Il-1β, Il-6 and TNF-α) after SCI in the spinal cords of neonates than in those of adults. At the same time, significantly fewer apoptotic neurons and greater axonal regeneration were observed in neonates in comparison with adults, which led to a marked recovery of locomotor function. This neonate-specific mechanism of inflammation regulation may have potential therapeutic applications in controlling inflammation after adult SCI.

Zinc deficiency impairs axonal regeneration and functional recovery after spinal cord injury by modulating macrophage polarization via NF-κB pathway

Background

Spinal cord injury (SCI) is a devastating disease that results in permanent paralysis. Currently, there is no effective treatment for SCI, and it is important to identify factors that can provide therapeutic intervention during the course of the disease. Zinc, an essential trace element, has attracted attention as a regulator of inflammatory responses. In this study, we investigated the effect of zinc status on the SCI pathology and whether or not zinc could be a potential therapeutic target.

Methods

We created experimental mouse models with three different serum zinc concentration by changing the zinc content of the diet. After inducing contusion injury to the spinal cord of three mouse models, we assessed inflammation, apoptosis, demyelination, axonal regeneration, and the number of nuclear translocations of NF-κB in macrophages by using qPCR and immunostaining. In addition, macrophages in the injured spinal cord of these mouse models were isolated by flow cytometry, and their intracellular zinc concentration level and gene expression were examined. Functional recovery was assessed using the open field motor score, a foot print analysis, and a grid walk test. Statistical analysis was performed using Wilcoxon rank-sum test and ANOVA with the Tukey-Kramer test.

Results

In macrophages after SCI, zinc deficiency promoted nuclear translocation of NF-κB, polarization to pro-inflammatory like phenotype and expression of pro-inflammatory cytokines. The inflammatory response exacerbated by zinc deficiency led to worsening motor function by inducing more apoptosis of oligodendrocytes and demyelination and inhibiting axonal regeneration in the lesion site compared to the normal zinc condition. Furthermore, zinc supplementation after SCI attenuated these zinc-deficiency-induced series of responses and improved motor function.

Conclusion

We demonstrated that zinc affected axonal regeneration and motor functional recovery after SCI by negatively regulating NF-κB activity and the subsequent inflammatory response in macrophages. Our findings suggest that zinc supplementation after SCI may be a novel therapeutic strategy for SCI.

Bone marrow-derived fibroblast migration via periostin causes irreversible arthrogenic contracture after joint immobilization

Joint contracture causes distressing permanent mobility disorder due to trauma, arthritis, and aging, with no effective treatment available. A principal and irreversible cause of joint contracture has been regarded as the development of joint capsule fibrosis. However, the molecular mechanisms underlying contracture remain unclear. We established a mouse model of knee joint contracture, revealing that fibrosis in joint capsules causes irreversible contracture. RNA-sequencing of contracture capsules demonstrated a marked enrichment of the genes involved in the extracellular region, particularly periostin (Postn). Three-dimensional magnetic resonance imaging and immunohistological analysis of contracture patients revealed posterior joint capsule thickening with abundant type I collagen (Col1a2) and POSTN in humans. Col1a2-GFP^TG ; Postn^-/- mice and chimeric mice with Col1a2-GFP^TG ; tdTomato^TG bone marrow showed fibrosis in joint capsules caused by bone marrow-derived fibroblasts, and POSTN promoted the migration of bone marrow-derived fibroblasts, contributing to fibrosis and contracture. Conversely, POSTN-neutralizing antibody attenuated contracture exacerbation. Our findings identified POSTN as a key inducer of fibroblast migration that exacerbates capsule fibrosis, providing a potential therapeutic strategy for joint contracture.

Glial scar survives until the chronic phase by recruiting scar-forming astrocytes after spinal cord injury

Spinal cord injury (SCI) causes reactive astrogliosis, the sequential phenotypic change of astrocytes in which naïve astrocytes (NAs) transform into reactive astrocytes (RAs) and subsequently become scar-forming astrocytes (SAs), resulting in glial scar formation around the lesion site and thereby limiting axonal regeneration and motor/sensory functional recovery. Inhibiting the transformation of RAs into SAs in the acute phase attenuates the reactive astrogliosis and promotes regeneration. However, whether or not SAs once formed can revert to RAs or SAs is unclear. We performed selective isolation of astrocytes from glial scars at different time points for a gene expression analysis and found that the expression of Sox9, an important transcriptional factor for glial cell differentiation, was significantly increased in chronic phase astrocytes (CAs) compared to SAs in the sub-acute phase. Furthermore, CAs showed a significantly lower expression of chondroitin sulfate proteoglycan (CSPG)-related genes than SAs. These results indicated that SAs changed their phenotypes according to the surrounding environment of the injured spinal cord over time. Even though the integrin-N-cadherin pathway is critical for glial scar formation, collagen-I-grown scar-forming astrocytes (Col-I-SAs) did not change their phenotype after depleting the effect of integrin or N-cadherin. In addition, we found that Col-I-SAs transplanted into a naïve spinal cord formed glial scar again by maintaining a high expression of genes involved in the integrin-N-cadherin pathway and a low expression of CSPG-related genes. Interestingly, the transplanted Col-I-SAs changed NAs into SAs, and anti-β₁-integrin antibody blocked the recruitment of SAs while reducing the volume of glial scar in the chronic phase. Our findings indicate that while the characteristics of glial scars change over time after SCI, SAs have a cell-autonomous function to form and maintain a glial scar, highlighting the basic mechanism underlying the persistence of glial scars after central nervous system injury until the chronic phase, which may be a therapeutic target.

Zinc chelator treatment in crush syndrome model mice attenuates ischemia-reperfusion-induced muscle injury due to suppressing of neutrophil infiltration

In crush syndrome, massive muscle breakdown resulting from ischemia-reperfusion muscle injury can be a life-threatening condition that requires urgent treatment. Blood reperfusion into the ischemic muscle triggers an immediate inflammatory response, and neutrophils are the first to infiltrate and exacerbate the muscle damage. Since free zinc ion play a critical role in the immune system and the function of neutrophils is impaired by zinc depletion, we hypothesized that the administration of a zinc chelator would be effective for suppressing the inflammatory reaction at the site of ischemia-reperfusion injury and for improving of the pathology of crush syndrome. A crush syndrome model was created by using a rubber tourniquet to compress the bilateral hind limbs of mice at 8 weeks. A zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine (TPEN) was administered immediately after reperfusion in order to assess the anti-inflammatory effect of the chelator for neutrophils. Histopathological evaluation showed significantly less muscle breakdown and fewer neutrophil infiltration in TPEN administration group compared with control group. In addition, the expression levels of inflammatory cytokine and chemokine such as IL-6, TNFα, CXCL1, CXCL2, CXCR2, CCL2 in ischemia-reperfusion injured muscle were significantly suppressed with TPEN treatment. Less dilatation of renal tubules in histological evaluation in renal tissue and significantly better survival rate were demonstrated in TPEN treatment for ischemia-reperfusion injury in crush syndrome. The findings of our study suggest that zinc chelators contributed to the resolution of exacerbation of the inflammatory response and attenuation of muscle breakdown in the acute phase after crush syndrome. In addition, our strategy of attenuation of the acute inflammatory reaction by zinc chelators may provide a promising therapeutic strategy not only for crush syndrome, but also for other diseases driven by inflammatory reactions.

Development of a radiopaque tiltmeter to improve reproducibility for Fowler's position on chest radiography

INTRODUCTION

We have developed a novel radiopaque tiltmeter (ROT) that can indicate patient tilt during a radiography examination and display it on X-ray images. This study evaluated the effect of variation of patient tilt on the reproducibility of Fowler's position for chest radiography and the accuracy of the ROT.

METHODS

We evaluated the reproducibility of Fowler's position based on changes from the first day in the central venous catheter (CVC) tip position and the cardiothoracic ratio (CTR) with and without a digital tiltmeter to verify its efficacy in patients who underwent mobile chest radiography. The ROT contains radiopaque liquid consisting of white barium sulfate solution and oil and has a scale bar of 15°-75° with increments of 15° to indicate ROT tilt. The ROT tilt was increased from 10° to 80° in increments of 10°. We then evaluated (1) the difference between the ROT tilt and the tilt measured with a digital tiltmeter, and (2) the ROT tilt displayed on the X-ray image.

RESULTS

With regard to reproducibility in Fowler's position, changes in the CVC tip position were 2.8 ± 3.9 mm and 10.7 ± 10.6 mm with and without the tiltmeter, respectively (p < 0.05) and the respective rates of change in the CTR were 0.7% ± 0.6% and 4.0% ± 2.1% (p < 0.05). Differences between the ROT tilt and the tilt measured by the digital tiltmeter were within ±2.5°. All ROT tilts displayed on the X-ray images were recognized exactly as each tilt.

CONCLUSION

Our novel ROT had the potential to accurately indicate patient tilt during chest radiography, which could be helpful in terms of reproducibility and precise follow-up.

IMPLICATIONS FOR PRACTICE

Use of the ROT for determination of patient tilt can improve reproducibility in Fowler's position, allowing more accurate serial X-ray imaging.

Microglial inflammation after chronic spinal cord injury is enhanced by reactive astrocytes via the fibronectin/β1 integrin pathway

BACKGROUND

After spinal cord injury (SCI), glial scarring is mainly formed around the lesion and inhibits axon regeneration. Recently, we reported that anti-β1 integrin antibody (β1Ab) had a therapeutic effect on astrocytes by preventing the induction of glial scar formation. However, the cellular components within the glial scar are not only astrocytes but also microglia, and whether or not β1Ab treatment has any influence on microglia within the glial scar remains unclear.

METHODS

To evaluate the effects of β1Ab treatment on microglia within the glial scar after SCI, we applied thoracic contusion SCI to C57BL/6N mice, administered β1Ab in the sub-acute phase, and analyzed the injured spinal cords with immunohistochemistry in the chronic phase. To examine the gene expression in microglia and glial scars, we selectively collected microglia with fluorescence-activated cell sorting and isolated the glial scars using laser-captured microdissection (LMD). To examine the interaction between microglia and astrocytes within the glial scar, we stimulated BV-2 microglia with conditioned medium of reactive astrocytes (RACM) in vitro, and the gene expression of TNFα (pro-inflammatory M1 marker) was analyzed via quantitative polymerase chain reaction. We also isolated both naïve astrocytes (NAs) and reactive astrocytes (RAs) with LMD and examined their expression of the ligands for β1 integrin receptors. Statistical analyses were performed using Wilcoxon's rank-sum test.

RESULTS

After performing β1Ab treatment, the microglia were scattered within the glial scar and the expression of TNFα in both the microglia and the glial scar were significantly suppressed after SCI. This in vivo alteration was attributed to fibronectin, a ligand of β1 integrin receptors. Furthermore, the microglial expression of TNFα was shown to be regulated by RACM as well as fibronectin in vitro. We also confirmed that fibronectin was secreted by RAs both in vitro and in vivo. These results highlighted the interaction mediated by fibronectin between RAs and microglia within the glial scar.

CONCLUSION

Microglial inflammation was enhanced by RAs via the fibronectin/β1 integrin pathway within the glial scar after SCI. Our results suggested that β1Ab administration had therapeutic potential for ameliorating both glial scar formation and persistent neuroinflammation in the chronic phase after SCI.

Tranexamic acid reduces heme cytotoxicity via the TLR4/TNF axis and ameliorates functional recovery after spinal cord injury

BACKGROUND

Spinal cord injury (SCI) is a catastrophic trauma accompanied by intralesional bleeding and neuroinflammation. Recently, there is increasing interest in tranexamic acid (TXA), an anti-fibrinolytic drug, which can reduce the bleeding volume after physical trauma. However, the efficacy of TXA on the pathology of SCI remains unknown.

METHODS

After producing a contusion SCI at the thoracic level of mice, TXA was intraperitoneally administered and the bleeding volume in the lesion area was quantified. Tissue damage was evaluated by immunohistochemical and gene expression analyses. Since heme is one of the degraded products of red blood cells (RBCs) and damage-associated molecular pattern molecules (DAMPs), we examined the influence of heme on the pathology of SCI. Functional recovery was assessed using the open field motor score, a foot print analysis, a grid walk test, and a novel kinematic analysis system. Statistical analyses were performed using Wilcoxon's rank-sum test, Dunnett's test, and an ANOVA with the Tukey-Kramer post-hoc test.

RESULTS

After SCI, the intralesional bleeding volume was correlated with the heme content and the demyelinated area at the lesion site, which were significantly reduced by the administration of TXA. In the injured spinal cord, toll-like receptor 4 (TLR4), which is a DAMP receptor, was predominantly expressed in microglial cells. Heme stimulation increased TLR4 and tumor necrosis factor (TNF) expression levels in primary microglial cells in a dose-dependent manner. Similarly to the in vitro experiments, the injection of non-lysed RBCs had little pathological influence on the spinal cord, whereas the injection of lysed RBCs or heme solution significantly upregulated the TLR4 and TNF expression in microglial cells. In TXA-treated SCI mice, the decreased expressions of TLR4 and TNF were observed at the lesion sites, accompanied by a significant reduction in the number of apoptotic cells and better functional recovery in comparison to saline-treated control mice.

CONCLUSION

The administration of TXA ameliorated the intralesional cytotoxicity both by reducing the intralesional bleeding volume and preventing heme induction of the TLR4/TNF axis in the SCI lesion. Our findings suggest that TXA treatment may be a therapeutic option for acute-phase SCI.

Macrophage centripetal migration drives spontaneous healing process after spinal cord injury

Traumatic spinal cord injury (SCI) brings numerous inflammatory cells, including macrophages, from the circulating blood to lesions, but pathophysiological impact resulting from spatiotemporal dynamics of macrophages is unknown. Here, we show that macrophages centripetally migrate toward the lesion epicenter after infiltrating into the wide range of spinal cord, depending on the gradient of chemoattractant C5a. However, macrophages lacking interferon regulatory factor 8 (IRF8) cannot migrate toward the epicenter and remain widely scattered in the injured cord with profound axonal loss and little remyelination, resulting in a poor functional outcome after SCI. Time-lapse imaging and P2X/YRs blockade revealed that macrophage migration via IRF8 was caused by purinergic receptors involved in the C5a-directed migration. Conversely, pharmacological promotion of IRF8 activation facilitated macrophage centripetal movement, thereby improving the SCI recovery. Our findings reveal the importance of macrophage centripetal migration via IRF8, providing a novel therapeutic target for central nervous system injury.

The acute phase serum zinc concentration is a reliable biomarker for predicting the functional outcome after spinal cord injury

Background

Spinal cord injury (SCI) is a devastating disorder for which the accurate prediction of the functional prognosis is urgently needed. Due to the lack of reliable prediction methods, the acute evaluation of SCI severity and therapeutic intervention efficacy is extremely difficult, presenting major obstacles to the development of acute SCI treatment. We herein report a novel method for accurately predicting the functional prognosis using the acute-phase serum zinc concentration after SCI.

Methods

We produced experimental animal SCI models with different prognoses and examined the relationship among the SCI severity, functional outcome, and acute-phase serum zinc concentration. We also examined whether we could predict the functional prognosis by evaluating the serum zinc concentration within 72 h after SCI in a human prospective study.

Findings

In a mouse model, the acute serum zinc concentrations decreased in proportion to SCI severity and the serum zinc concentrations at 12 h after SCI accurately predicted the functional prognosis. We clarified the mechanism underlying this serum zinc proportional decrease, showing that activated monocytes took up zinc from blood-serum and then infiltrated the lesion area in a severity-dependent manner. A non-linear regression analysis of 38 SCI patients showed that the serum zinc concentrations in the acute-phase accurately predicted the long-term functional outcome (R² = 0·84) more accurately than any other previously reported acute-phase biomarkers.

Interpretation

The acute-phase serum zinc concentration could be a useful biomarker for predicting the functional prognosis. This simple method will allow for more objective clinical trials and the development of patient-tailored treatment for SCI.

Pathological changes of distal motor neurons after complete spinal cord injury

Traumatic spinal cord injury (SCI) causes serious disruption of neuronal circuits that leads to motor functional deficits. Regeneration of disrupted circuits back to their original target is necessary for the restoration of function after SCI, but the pathophysiological condition of the caudal spinal cord has not been sufficiently studied. Here we investigated the histological and biological changes in the distal part of the injured spinal cord, using a mice model of complete thoracic SCI in the chronic stage (3 months after injury). Atrophic changes were widely observed in the injured spinal cord both rostral and caudal to the lesion, but the decrease in area was mainly in the white matter in the rostral spinal cord while both the white and gray matter decreased in the caudal spinal cord. The number of the motor neurons was maintained in the chronic phase of injury, but the number of presynaptic boutons decreased in the lumbar motor neurons caudal to the lesion. Using laser microdissection, to investigate gene expressions in motor neurons caudal to the lesion, we observed a decrease in the expressions of neuronal activity markers. However, we found that the synaptogenic potential of postsynapse molecules was maintained in the motor neurons after SCI with the expression of acetylcholine-related molecules actually higher after SCI. Collectively, our results show that the potential of synaptogenesis is maintained in the motor neurons caudal to the lesion, even though presynaptic input is decreased. Although researches into SCI concentrate their effort on the lesion epicenter, our findings suggest that the area caudal to the lesion could be an original therapeutic target for the chronically injured spinal cord.

Periostin Promotes Fibroblast Migration and Inhibits Muscle Repair After Skeletal Muscle Injury

BACKGROUND

Skeletal muscle injury (SMI) can cause physical disability due to insufficient recovery of the muscle. The development of muscle fibrosis after SMI has been widely regarded as a principal cause of this failure to recover. Periostin (Postn) exacerbates tissue fibrosis in various organs. We investigated whether Postn is involved in the pathophysiology after SMI.

METHODS

Partial laceration injuries of the gastrocnemius were created in wild-type (WT) and Postn knockout (Postn) mice. We examined the expression of the Postn gene before and after SMI. Regeneration and fibrosis of skeletal muscle were evaluated by histological analyses, and recovery of muscle strength was measured by physiological testing. Immunohistochemistry was used to examine the number and proliferative potential of infiltrating fibroblasts in injured muscle. A trans-well migration assay was used to assess the migration capability of fibroblasts. Control immunoglobulin G (IgG) or Postn-neutralizing antibody (Postn-nAb) was injected into injured muscle at 7 and 14 days after injury (dpi). We evaluated the effects of Postn-nAb on muscle repair after SMI.

RESULTS

The expression of Postn was dramatically upregulated after SMI. Compared with WT mice, Postn mice had improved muscle recovery and attenuated fibrosis as well as a significantly reduced number of infiltrating fibroblasts. The proliferative potential of these fibroblasts in WT and Postn mice was comparable at 14 dpi; however, the migration capability of fibroblasts was significantly enhanced in the presence of Postn (mean, 258%; 95% confidence interval, 183% to 334%). Moreover, the administration of Postn-nAb inhibited fibroblast infiltration and promoted muscle repair after SMI.

CONCLUSIONS

Postn exacerbates fibrotic scar formation through the promotion of fibroblast migration into injured muscle after SMI. Treatment with Postn-nAb is effective for attenuating fibrosis and improving muscle recovery after SMI.

CLINICAL RELEVANCE

Our findings may provide a potential therapeutic strategy to enhance muscle repair and functional recovery after SMI.

Macrophage Infiltration Is a Causative Factor for Ligamentum Flavum Hypertrophy through the Activation of Collagen Production in Fibroblasts

Ligamentum flavum (LF) hypertrophy causes lumbar spinal canal stenosis, leading to leg pain and disability in activities of daily living in elderly individuals. Although previous studies have been performed on LF hypertrophy, its pathomechanisms have not been fully elucidated. In this study, we demonstrated that infiltrating macrophages were a causative factor for LF hypertrophy. Induction of macrophages into the mouse LF by applying a microinjury resulted in LF hypertrophy along with collagen accumulation and fibroblasts proliferation at the injured site, which were very similar to the characteristics observed in the severely hypertrophied LF of human. However, we found that macrophage depletion by injecting clodronate-containing liposomes counteracted LF hypertrophy even with microinjury. For identification of fibroblasts in the LF, we used collagen type I α₂ linked to green fluorescent protein transgenic mice and selectively isolated green fluorescent protein-positive fibroblasts from the microinjured LF using laser microdissection. A quantitative RT-PCR on laser microdissection samples revealed that the gene expression of collagen markedly increased in the fibroblasts at the injured site with infiltrating macrophages compared with the uninjured location. These results suggested that macrophage infiltration was crucial for LF hypertrophy by stimulating collagen production in fibroblasts, providing better understanding of the pathophysiology of LF hypertrophy.

Interaction of reactive astrocytes with type I collagen induces astrocytic scar formation through the integrin-N-cadherin pathway after spinal cord injury

Central nervous system (CNS) injury transforms naive astrocytes into reactive astrocytes, which eventually become scar-forming astrocytes that can impair axonal regeneration and functional recovery. This sequential phenotypic change, known as reactive astrogliosis, has long been considered unidirectional and irreversible. However, we report here that reactive astrocytes isolated from injured spinal cord reverted in retrograde to naive astrocytes when transplanted into a naive spinal cord, whereas they formed astrocytic scars when transplanted into injured spinal cord, indicating the environment-dependent plasticity of reactive astrogliosis. We also found that type I collagen was highly expressed in the spinal cord during the scar-forming phase and induced astrocytic scar formation via the integrin-N-cadherin pathway. In a mouse model of spinal cord injury, pharmacological blockade of reactive astrocyte-type I collagen interaction prevented astrocytic scar formation, thereby leading to improved axonal regrowth and better functional outcomes. Our findings reveal environmental cues regulating astrocytic fate decisions, thereby providing a potential therapeutic target for CNS injury.

Periostin Promotes Scar Formation through the Interaction between Pericytes and Infiltrating Monocytes/Macrophages after Spinal Cord Injury

Scar formation is a prominent pathological feature of traumatic central nervous system (CNS) injury, which has long been implicated as a major impediment to the CNS regeneration. However, the factors affecting such scar formation remain to be elucidated. We herein demonstrate that the extracellular matrix protein periostin (POSTN) is a key player in scar formation after traumatic spinal cord injury (SCI). Using high-throughput RNA sequencing data sets, we found that the genes involved in the extracellular region, such as POSTN, were significantly expressed in the injured spinal cord. The expression of POSTN peaked at 7 days after SCI, predominantly in the scar-forming pericytes. Notably, we found that genetic deletion of POSTN in mice reduced scar formation at the lesion site by suppressing the proliferation of the pericytes. Conversely, we found that recombinant POSTN promoted the migration capacity of the monocytes/macrophages and increased the expression of tumor necrosis factor-α from the monocytes/macrophages in vitro, which facilitated the proliferation of pericytes. Furthermore, we revealed that the pharmacological blockade of POSTN suppressed scar formation and improved the long-term functional outcome after SCI. Our findings suggest a potential mechanism whereby POSTN regulates the scar formation after SCI and provide significant evidence that POSTN is a promising therapeutic target for CNS injury.

The use of a two-way analysis of variance to compare the methods for the assay of anhydrous dibasic calcium phosphate in the European, Japanese and United States Pharmacopoeias

Tri-PEC (IPEC-Americas, IPEC-Europe and JPEC) carried out a two-way analysis of variance (Round Robin testing) for the assay of Anhydrous Dibasic Calcium Phosphate (CaHPO4) at the request of the Pharmacopoeial Discussion Group (PDG). On the basis of the result obtained, the difference in the assay results for anhydrous CaHPO4 using the different methods of the 3 Pharmacopoeias was not significant, while the difference in the results for the 3 different batch samples tested by 3 different methods was significant (p < 0.05). On the basis of these results, the methods from the 3 Pharmacopoeias, did not give different results, and thus the methods themselves should be considered equivalent.

Visualization of the terminal structure of rice chromosomes 6 and 12 with multicolor FISH to chromosomes and extended DNA fibers

High-resolution fluorescence in situ hybridization (FISH) on interphase and pachytene nuclei, and extended DNA fibers enabled microscopic distinction of DNA sequences less than a few thousands of base pairs apart. We applied this technique to reveal the molecular organization of telomere ends in japonica rice (Oryza sativa ssp. japonica), which consist of the Arabidopsis type TTTAGGG heptameric repeats and the rice specific subtelomeric tandem repeat sequence A (TrsA). Southern hybridizations of DNA digested with Bal31 and EcoRI, and FISH on chromosomes and extended DNA fibers demonstrated that (1) all chromosome ends possess the telomere tandem repeat measuring 3-4 kb; (2) the subtelomeric TrsA occurs only at the ends of the long arms of chromosomes 6 and 12, and measure 6 and 10 kb, which corresponds to 231 and 682 copies for these sites, respectively; (3) the telomere and TrsA repeats are separated by at most a few thousands of intervening nucleotide sequences. The molecular organization for a general telomere organization in plant chromosomes is discussed.

Di(2-ethylhexyl)phthalate induces hepatocellular adenoma in transgenic mice carrying a human prototype c-Ha-ras gene in a 26-week carcinogenicity study

To evaluate the transgenic mouse carrying a human prototype c-Ha-ras gene (rasH2 mouse) as a model for 26-week carcinogenicity tests, Di(2-ethylhexyl)phthalate (DEHP), a peroxisome proliferator, was administered to 15 rasH2 mice/sex/group at concentrations of 1,500, 3,000 or 6,000 ppm, and to 15 wild-type (non-Tg) mice/sex/group at a concentration of 6,000 ppm in their diets for 26 weeks. Survival rates and food consumption in the groups treated with DEHP and in the control group were similar. Body weight gain in rasH2 and non-Tg mice at 6,000 ppm in the terminal week decreased about 10% as compared to the control group. Common findings related to treatment with DEHP in rasH2 and non-Tg mice included hypertrophy with coarse granules and deposit of pigment in the liver, hydronephrosis and tubular regeneration in the kidney, focal atrophy in the testis, and increased eosinophilic body in the nasal cavity. Hepatocellular adenoma was induced by treatment with DEHP, and was confined to male rasH2; mice the incidence being 7%(1/15), 13%(2/15), and 27%(4/15) in the 1,500-, 3,000-, and 6,000-ppm group, respectively. Point mutation was not detected in codon 12 and 61 of human c-Ha-ras transgene upon DNA analyses on frozen samples taken from these hepatocellular adenomas. From the results obtained in this 26-week carcinogenicity study, it is concluded that DEHP is a hepato-carcinogen for transgenic mouse carrying a human prototype c-Ha-ras gene.

An iridoid gentiobioside, a benzophenone glucoside and acylated flavone C-glycosides from Tripterospermum japonicum (Sieb. et Zucc.) Maxim

From aerial parts of Tripterospermum japonicum, 6'-O-beta-D-glucopyranosylmorroniside, benzophenone glucoside, named triptephenoside and 2'''- and 4'''-O-acetyl-2''-O-alpha-L-rhamnopyranosylisovitexins were isolated, along with known iridoid and secoiridoid glucosides, and C-glycosyl flavones.

State-selective optical near-field resonant ionization spectroscopy of atoms near a dielectric surface

Spin-sensitive optical near-field microscopy and spectroscopy are proposed based on the study on the conserved quantities in optical near-field interactions of atoms with dielectric surfaces. A two-step photoionization spectra of Cs atoms resolving hyperfine structures are demonstrated near a planar dielectric surface by using evanescent waves. These techniques of state/spin-selective excitation and highly sensitive detection, combined with the techniques of optical pumping, will open up possibilities of space- and polarization-sensitive detection of optical near-fields using atomic probes. This novel method provides us with a useful technique for the observation of polarization nature of the optical near-field and controlling the spin states of mesoscopic electronic systems.

First presentation of polymyositis postpartum following intrauterine fetal death

We present a case of polymyositis (PM) following intrauterine fetal death. The first presentation of PM in the patient was during postpartum. The patient was referred to our hospital because of a fever of unknown cause 13 d after delivery of dead fetus at 32 weeks' gestation. PM was diagnosed based on the increased serum creatine phosphokinase level, typical electromyogram findings and characteristic muscle biopsy findings.

Quantification of total genomic DNA and selected repetitive sequences reveals concurrent changes in different DNA families in indica and japonica rice

This paper describes a fluorescence in situ hybridization (FISH) analysis of three different repetitive sequence families, which were mapped to mitotic metaphase chromosomes and extended DNA fibers (EDFs) of the two subspecies of rice (OrYza sativa), indica and japonica (2n = 2x = 24). The repeat families studied were (1) the tandem repeat sequence A (TrsA), a functionally non-significant repeat; (2) the [TTTA-GGG]n telomere sequence, a non-transcribed, tandemly repeated but functionally significant repeat; and (3) the 5S ribosomal RNA (5S rDNA). FISH of the TrsA repeat to metaphase chromosomes of indica and japonica cultivars revealed clear signals at the distal ends of twelve and four chromosomes, respectively. As shown in a previous report, the 17S ribosomal RNA genes (17S rDNA) are located at the nucleolus organizers (NORs) on chromosomes 9 and 10 of the indica cultivar. However, the japonica rice lacked the rDNA signals on chromosome 10. The size of the 5S rDNA repeat block, which was mapped on the chromosome 11 of both cultivars, was 1.22 times larger in the indica than in the japonica genome. The telomeric repeat arrays at the distal ends of all chromosome arms were on average three times longer in the indica genome than in the japonica genome. Flow cytometric measurements revealed that the nuclear DNA content of indica rice is 9.7% higher than that of japonica rice. Our data suggest that different repetitive sequence families contribute significantly to the variation in genome size between indica and japonica rice, though to different extents. The increase or decrease in the copy number of several repetitive sequences examined here may indicate the existence of a directed change in genome size in rice. Possible reasons for this phenomenon of concurrent evolution of various repeat families are discussed.

Rat liver in vivo replicative DNA synthesis test for short-term prediction of nongenotoxic (Ames-negative) hepatocarcinogenicity: a collaborative study of the Nongenotoxic Carcinogen Study Group of Japan

A collaborative study was conducted to evaluate whether a replicative DNA synthesis (RDS) test using the rat liver can detect nongenotoxic (Ames-negative) hepatocarcinogens with three or seven daily administrations at dose-levels effective in long-term bioassays. The assay methods were well-validated by the 14 participants. Of six compounds tested, carbon tetrachloride (50 and 100 mg/kg), clofibrate (125 and 250 mg/kg), diethylstilbestrol (0.125 and 0.25 mg/kg) and urethane (100 mg/kg) gave positive results, methyl carbamate (200 and 400 mg/kg) exerted equivocal effects, and D,L-ethionine (125 mg/kg) failed to elevate RDS. These findings suggest that the RDS test can detect many nongenotoxic rat hepatocarcinogens with short-term administration at dose-levels used in long-term bioassays.

A collagen network formation effector from leaves of Premna subscandens

As a part of the search for biologically active plant products, M cells, which form a collagen fiber network in vitro after a prolonged culture period, were used. The n-BuOH-soluble fraction of a methanol extract of leaves of Premna subscandens exhibited promotion of collagen network formation by M cells. Extensive isolation work guided by a bioassay afforded a phenylethanoid, acteoside, as an active compound.

Effects of fetal endotoxin administration on plasma prostaglandin f(2alpha) and cortisol levels in late-gestation fetal goats

OBJECTIVE

Fetal plasma prostaglandin F(2alpha) (PGF(2alpha)) and cortisol responses to fetal endotoxin administration were evaluated in late-gestation goats (n = 9).

METHODS

After endotoxin (Escherichia coli, O111:B4 lipopolysaccharide) administration, fetal plasma PGF(2alpha) and cortisol levels, fetal blood gases and pH were measured periodically.

RESULTS

After endotoxin administration, fetal plasma cortisol levels increased to 9.8 +/- 1.4 and 9.4 +/- 1. 2 ng/ml after 1 and 3 h, respectively (p < 0.05) and PGF(2alpha) levels did not change throughout the study.

CONCLUSIONS

These results suggest that absent PGF(2alpha) and attenuated cortisol responses to fetal endotoxin administration, relative to the adult, may be a self-protective mechanism which diminishes the likelihood of premature delivery.

Angiotensin II type 2 receptor is upregulated in human heart with interstitial fibrosis, and cardiac fibroblasts are the major cell type for its expression

The expression pattern of angiotensin (Ang) II type 2 receptor (AT2-R) in the remodeling process of human left ventricles (LVs) remains poorly defined. We analyzed its expression at protein, mRNA, and cellular levels using autopsy, biopsy, or operation LV samples from patients with failing hearts caused by acute (AMI) or old (OMI) myocardial infarction and idiopathic dilated cardiomyopathy (DCM) and also examined functional biochemical responses of failing hearts to Ang II. In autopsy samples from the nonfailing heart group, the ratio of AT1-R and AT2-R was 59% and 41%, respectively. The expression of AT2-R was markedly increased in DCM hearts at protein (3.5-fold) and mRNA (3.1-fold) levels compared with AMI or OMI. AT1-R protein and mRNA levels in AMI hearts showed 1.5- and 2.1-fold increases, respectively, whereas in OMI and DCM hearts, AT1-R expression was significantly downregulated. AT1-R-mediated response in inositol phosphate production was significantly attenuated in LV homogenate from failing hearts compared with nonfailing hearts. AT2-R sites were highly localized in the interstitial region in either nonfailing or failing heart, whereas AT1-R was evenly distributed over myocardium at lower densities. Mitogen-activated protein kinase (MAPK) activation by Ang II was significantly decreased in fibroblast compartment from the failing hearts, and pretreatment with AT2-R antagonist caused an additional significant increase in Ang II-induced MAPK activity (36%). Cardiac hypertrophy suggested by atrial and brain natriuretic peptide levels was comparably increased in OMI and DCM, whereas accumulation of matrix proteins such as collagen type 1 and fibronectin was much more prominent in DCM than in OMI. These findings demonstrate that (1) AT2-R expression is upregulated in failing hearts, and fibroblasts present in the interstitial regions are the major cell type responsible for its expression, (2) AT2-R present in the fibroblasts exerts an inhibitory effect on Ang II-induced mitogen signals, and (3) AT1-R in atrial and LV tissues was downregulated during chronic heart failure, and AT1-R-mediated functional biochemical responsiveness was decreased in the failing hearts. Thus, the expression level of AT2-R is likely determined by the extent of interstitial fibrosis associated with heart failure, and the expression and function of AT1-R and AT2-R are differentially regulated in failing human hearts.

Pressure overload induces cardiac hypertrophy in angiotensin II type 1A receptor knockout mice

BACKGROUND

Many studies have suggested that the renin-angiotensin system plays an important role in the development of pressure overload-induced cardiac hypertrophy. Moreover, it has been reported that pressure overload-induced cardiac hypertrophy is completely prevented by ACE inhibitors in vivo and that the stored angiotensin II (Ang II) is released from cardiac myocytes in response to mechanical stretch and induces cardiomyocyte hypertrophy through the Ang II type 1 receptor (AT1) in vitro. These results suggest that the AT1-mediated signaling is critical for the development of mechanical stress-induced cardiac hypertrophy.

METHODS AND RESULTS

To determine whether AT1-mediated signaling is indispensable for the development of pressure overload-induced cardiac hypertrophy, pressure overload was produced by constricting the abdominal aorta of AT1A knockout (KO) mice. Quantitative reverse transcriptase-polymerase chain reaction revealed that the cardiac AT1 (probably AT1B) mRNA levels in AT1A KO mice were <10% of those of wild-type (WT) mice and were not affected by pressure overload. Chronic treatment with subpressor doses of Ang II increased left ventricular mass in WT mice but not in KO mice. Pressure overload, however, fully induced cardiac hypertrophy in KO as well as WT mice. There were no significant differences between WT and KO mice in expression levels of fetal-type cardiac genes, in the left ventricular wall thickness and systolic function as revealed by the transthoracic echocardiogram, or in the histological changes such as myocyte hypertrophy and fibrosis.

CONCLUSIONS

AT1-mediated Ang II signaling is not essential for the development of pressure overload-induced cardiac hypertrophy.

Acute pressure overload could induce hypertrophic responses in the heart of angiotensin II type 1a knockout mice

Increasing evidence has suggested that locally produced angiotensin II (Ang II) plays an important role in the development of cardiac hypertrophy through the Ang II type 1 receptor (AT1). We and others have recently reported that Ang II is critical for mechanical stress-induced hypertrophic responses in vitro. Using AT1a knockout (KO) mice, we examined whether Ang II is indispensable for pressure overload-induced cardiac hypertrophy in the present study. Reverse-transcriptase polymerase chain reaction analysis revealed that AT1 mRNA levels were <10% in the heart of KO mice compared with wild-type (WT) mice, but the Ang II type 2 receptor gene was expressed at almost the same levels in the hearts of both mice. Intravenous infusion of subpressor dose of Ang II induced c-fos gene expression in the hearts of WT mice but not KO mice. Acute pressure overload, however, induced expressions of immediate-early response genes and activations of mitogen-activated protein kinases in the hearts of KO mice as well as WT mice. Both basal and activated levels of all these responses were significantly higher in KO mice than in WT mice. Pressure overload markedly increased the heart weight-to-body weight ratio in both mice strains at 14 days after aortic banding. These results suggest that acute hypertrophic responses could be induced by pressure overload in the in vivo heart without AT1 signaling.

Angiotensin type 2 receptors are reexpressed by cardiac fibroblasts from failing myopathic hamster hearts and inhibit cell growth and fibrillar collagen metabolism

BACKGROUND

Angiotensin (Ang) II type 1 receptor (AT1-R) induces cardiomyocyte hypertrophy and fibroblast proliferation, whereas the physiological role of AT2-R in cardiac remodeling remains poorly defined.

METHODS AND RESULTS

Using Bio14.6 cardiomyopathic (CM) hamsters, we found that AT2-R sites were increased by 153% during heart failure compared with F1B controls. AT1-R numbers were increased by 72% in the hypertrophy stage and then decreased to the control level during heart failure. Such differential regulation of AT2-R and AT1-R during heart failure was consistent with changes in the respective mRNA levels. Autoradiography and immunocytochemistry revealed that both AT2-R and AT1-R are localized at higher densities in fibroblasts present in fibrous regions. Surrounding myocardium predominantly expressed AT1-R, but the level of expression was less than that in fibrous regions. Cardiac fibroblasts isolated from CM hearts during heart failure but not from control hamsters expressed AT2-R (30 fmol/mg protein). Using the cardiac fibroblasts expressing AT2-R, we found that Ang II stimulated net collagenous protein production by 48% and pretreatment with an AT2-R antagonist, PD123319, evoked a further elevation (83%). Ang II-induced synthesis of fibronectin and collagen type I were enhanced by 40% and 53%, respectively, by pretreatment with PD123319. Ang II-induced DNA synthesis (assessed by [3H]thymidine uptake) was significantly increased by PD123319, and the AT2-R agonist CGP42112A reduced the serum-stimulated increase in cell numbers by 23%. Treatment with an AT1-R antagonist, TCV116, for 20 weeks inhibited progression of interstitial fibrosis by 28%, whereas with 44-week PD123319 treatment but not 20-week treatment, the extent of the fibrous region was increased significantly, by 29%.

CONCLUSIONS

These findings demonstrate that AT2-R is re-expressed by cardiac fibroblasts present in fibrous regions in failing CM hearts and that the increased AT2-R exerts an anti-AT1-R action on the progression of interstitial fibrosis during cardiac remodeling by inhibiting both fibrillar collagen metabolism and growth of cardiac fibroblasts.

Down-regulation by cAMP of angiotensin II type 2 receptor gene expression in PC12 cells

The rat angiotensin II type 2 receptor (AT2-R) gene was isolated, and cis-regulatory regions in its 5'-flanking area were analyzed. Primer extension and RNase protection analyses revealed a single transcriptional initiation site at the position 24 bp downstream of the TATA box. The 5'-flanking region of AT2-R contained several cis-regulatory elements, such as AP-1, AP-2, C/EBP, NF-1, NF-IL6, NF-kappa B, and glucocorticoid- and cAMP-responsive elements (CRE). The treatment of PC12 cells with dibutyryl cAMP caused a marked decrease (90%) in the AT2-R mRNA level, which was blocked by the inhibitor of protein kinase A and did not require new protein synthesis. The protein level was also reduced 84% after a 24-h exposure to cAMP and the binding affinity was unchanged. The half-life of the AT2-R mRNA decreased -66% by cAMP as compared with control (18.4 +/- 0.4 h). Deletion and mutation analyses of the 5'-flanking region (1.2 Kb) revealed that there were one negative (-1,199 to -739) and two positive cis-regulatory regions (-739 to -436 and -59 to +45), and that the CRE motif located at -426 repressed (-23%) the promoter activity of the rat AT2-R gene. The region between -59 and +45 containing TATA box and AP-2 site accounted for 70% of the promoter activity. These findings indicate that the promoter activity of the rat AT2-R gene is modulated by several cis-regulatory regions and that cAMP markedly downregulates the expression of the AT2-R mainly by inducing AT2-R mRNA destabilization rather than CRE-mediated inhibition of the gene transcription. Thus, humoral factors that transduce cAMP as an intracellular signal may modulate AT2-R-mediated function of Ang II by reducing AT2-R expression.

Translational regulation of angiotensin II type 1A receptor. Role of upstream AUG triplets

The cDNA sequence of rat angiotensin II type 1A receptor (AT1AR) shows that AT1AR transcripts have AUG triplets in the 5'-leader region that may begin a short open reading frame encoding an 11-amino acid peptide. In this study, the mutational inactivation of the start codon of the short open reading frame in AT1AR-chloramphenicol acetyltransferase (CAT) reporter gene constructs resulted in a 2.6-fold increase in CAT activity, whereas CAT transcript levels were not affected. Furthermore, experiments with rat AT1AR cDNA-transfected Cos-7 cells revealed that mutagenesis of the upstream AUG increased the AT1AR protein up to 2.5-fold, although AT1AR transcript levels showed no changes. The synthetic peptide corresponding to the sequence of the short open reading frame significantly suppressed the amount of AT1AR product in the in vitro translation system. The inhibiting effect of the short open reading frame appears to operate at least in part at the level of translation initiation, because polysome analysis with transfected Cos-7 cells showed that mutagenesis of the upstream AUG resulted in a shift of AT1AR mRNA distribution from a smaller to larger fraction of polysomes. Taken together, these results show that the upstream AUG inhibits translational regulation, suggesting that the short open reading frame in the 5'-leader region of AT1AR transcripts has a certain role in the translation of AT1AR protein.

Mechanical stretch induces enhanced expression of angiotensin II receptor subtypes in neonatal rat cardiac myocytes

Mechanical stress plays a pivotal role in the development of cardiac hypertrophy during hemodynamic overload, and angiotensin (Ang) II secreted from stretched myocytes plays an important role in mechanical stretch-induced hypertrophy. In the present study, we examined stretch-induced expression of Ang II receptors in an in vitro stretch model using 1-day-old rat myocytes. Both Ang II type 1 receptor (AT1-R) and type 2 receptor (AT2-R) mRNA levels were upregulated by myocyte stretching with similar time courses: significant increases were evident 6 hours after stretching, maximal levels (2.8- and 3.3-fold, respectively) were observed at 12 hours, and these were sustained for up to 18 hours. Ang II receptor expression in fibroblast-rich cultures was not affected by stretching. Conditioned medium in which myocytes were stretched for 12 hours significantly downregulated AT1-R and AT2-R mRNA levels in recipient myocytes, and this effect was almost completely blocked by AT1-R antagonists but not AT2-R antagonists. Stretch-induced expression of AT1-R and AT2-R mRNAs was further increased by 27% and 31%, respectively, after pretreatment with AT1-R antagonists, suggesting that Ang II secreted from stretched myocytes downregulates both AT1-R and AT2-R. Western blot and binding assays showed that the number of AT1-Rs and AT2-Rs increased by 2.4- and 2.6-fold, respectively, without affecting receptor affinities. Inositol phosphate response to 0.5 mumol/L Ang II was enhanced 2.1-fold in stretched myocytes. Nuclear runoff assays and treatment with actinomycin D revealed that stretch-induced upregulation of AT1-R was mainly due to increased transcription, whereas that of AT2-R resulted from a stabilizing effect on AT2-R mRNA metabolism. Stretch-induced changes in levels of Ang II receptors were inhibited by genistein but not by H-7, staurosporin, and protein kinase C depletion or by BAPTA-AM. Exposure to cycloheximide did not affect stretch-induced changes. These findings indicate that nonsecretory pathways activated by myocyte stretching upregulate the expression of Ang II receptor subtypes transcriptionally and posttranscriptionally through mechanisms involving stretch-activated tyrosine kinases independently of de novo protein synthesis and that the AT1-R-mediated action of Ang II is functionally enhanced in stretched cardiac myocytes.

Regulation of sulphate assimilation in Saccharomyces cerevisiae

We examined how the activity of O-acetylserine and O-acetylhomoserine sulphydrylase (OAS/OAH) SHLase of Saccharomyces cerevisiae is affected by sulphur source added to the growth medium and genetic background of the strain. In a wild-type strain, the activity was repressed if methionine, cysteine or glutathione was added to the growth medium. However, in a strain deficient of cystathionine gamma-lyase, cysteine and glutathione were repressive, but methionine was not. In strains deficient of serine O-acetyltransferase (SATase), OAS/OAH SHLase activity was low regardless of sulphur source and was further lowered by cysteine and glutathione, but not by methionine. From these observations, we concluded that S-adenosylmethionine should be excluded from being the effector for regulation of OAS/OAH SHLase. Instead, we suspected that S. cerevisiae would have the same regulatory system as Escherichia coli for sulphate assimilation; i.e. cysteine inhibits SATase to lower the cellular concentration of OAS which is required for induction of the sulphate assimilation enzymes including OAS/OAH SHLase. Subsequently, we obtained data supporting this speculation.

First-trimester prenatal molecular diagnosis of infantile hypophosphatasia in a Japanese family

We obtained a prenatal molecular diagnosis during the first trimester in a Japanese woman whose first child (the proband) had been a compound heterozygote for infantile hypophosphatasia. We examined chorionic villus DNA samples obtained at 10 weeks of gestation for the base substitutions detected in the proband DNA using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and PCR-allele-specific oligonucleotide (ASO) analysis. The genotype of the fetus was the same as that of the proband. The same mobility shift patterns of single strand conformation polymorphism (SSCP) bands were observed in the fetus and the proband. This molecular approach to prenatal diagnosis appears to be more accurate than the enzymatic method and also more accurate and more rapid than the conventional RFLP method.

Regulation of angiotensin II type 2 receptor gene by the protein kinase C-calcium pathway

In the present study, rat angiotensin II type 2 (AT2) receptor expression was upregulated in confluence-arrested PC12 cells compared with expression in proliferating cells. Treatment with cycloheximide inhibited the increase in mRNA levels in confluent cells. The state of growth arrest by serum deprivation was associated with increased expression of the AT2 receptor, which was markedly suppressed by exposure to the active phorbol ester 12-O-tetradecanoylphorbol 13-acetate and the calcium ionophore A23187. Similar inhibitions were also observed in myocytes isolated from neonatal rat heart. The change in AT2 mRNA levels by serum deprivation was due to the increase in the gene transcription rate. The effect of 12-O-tetradecanoylphorbol 13-acetate was mediated through decreases in gene transcription and mRNA stability, whereas A23187 affected mRNA stability. Vasoactive substances with the protein kinase C-calcium pathway, such as norepinephrine and angiotensin II, also downregulated the AT2 mRNA level in myocytes. These findings indicate that the expression of AT2 receptor in PC12 cells is regulated in a growth state-dependent manner, which is involved in confluence-induced new protein synthesis, thus providing a means by which cells can modulate their responsiveness to external angiotensin II stimulus. The activation of protein kinase C or calcium mobilization modifies this regulatory mechanism, suggesting that neurotransmitters or vasoactive substances with the protein kinase C-calcium pathway at least in part affect neuronal activity or blood pressure control by downregulating AT2 receptor expression.

Gene transcription of angiotensin II type 2 receptor is repressed by growth factors and glucocorticoids in PC12 cells

The rat angiotensin II type 2 receptor (AT2-R) expression was markedly downregulated by the mitogenic action of serum, growth factors and dexamethasone. The regulation by serum or growth factors did not affect the AT2-R mRNA half-life (18 h), whereas the AT2-R half-lives of dexamethasone-treated cells and proliferating cells decreased to 10 h and 15 h, respectively. Nuclear run-off assays indicated the mechanism of repression of AT2-R expression by serum, growth factors and dexamethasone or in proliferating cells to be, in large part, transcriptional. These findings indicate that transcription of the AT2-R gene is regulated in a growth state-dependent manner and suggest that this regulation provides a means by which cells can modulate their responsiveness to the actions of angiotensin II mediated through AT2-R.

Identification of a negative cis-regulatory element and trans-acting protein that inhibit transcription of the angiotensin II type 1a receptor gene

The rat angiotensin II type 1a receptor (AT1a-R) gene is expressed in a cell-specific manner. We demonstrated that the negative regulatory element (NRE) between -489 and -331 is active in PC12 cells (Murasawa, S., Matsubara, H., Urakami, M., and Inada, M. (1993) J. Biol. Chem. 268, 26996-27003). Gel retardation assays confirmed that PC12 cells have a trans-acting factor bound to the NRE. By means of a DNase I footprint assay we identified the core of the NRE as an (A+T)-rich sequence (TAATCTTTTATTTTA) located at nucleotides -456 to -442. Oligonucleotides corresponding to the NRE core sequence bound to nuclear protein. Site-directed mutagenesis at nucleotides -451 to -448 eliminated the specific protein/DNA binding and restored expression of the AT1a-R in transient transfection assays (2.7-fold increase). The NRE did not negatively affect the thymidine kinase promoter. No homology was found with known NREs, suggesting that this is a novel NRE. Southwestern blotting revealed a 53-kDa, specific binding protein in PC12 cells and the rat brain, but not in the liver, spleen, adrenal gland, and kidney. These findings demonstrate that the NRE of the rat AT1a-R is an (A+T)-rich sequence located at nucleotides -456 to -442 and the 53-kDa protein is a specific binding protein, and suggest that this protein may be a trans-acting factor which determines the neuron-specific down-regulation of the AT1a-R gene.

Structure of the rat V1a vasopressin receptor gene and characterization of its promoter region and complete cDNA sequence of the 3'-end

The gene encoding the rat V1a arginine vasopressin (AVP) receptor was isolated, and its structural organization and 5'-flanking region were characterized. In addition, the complete cDNA sequence of the major transcript of the rat V1a receptor gene was determined. Southern blots demonstrated a single copy of the V1a receptor gene in the rat genome, spanning a region of 3.8 kilobases (kb) and consisting of two exons and one intron (1.8 kb). The location of the intron was unique among G protein-coupled receptor genes in that the first exon encodes six of the seven transmembrane regions, the seventh region being encoded by the second exon. Primer extension, RNase protection, and rapid amplification of the 5'-end of the cDNA identified three transcriptional initiation sites (-405, -243, and -237), the major transcription initiation sites being mapped to positions -243 and -237 base pairs (bp) upstream of the ATG initiation codon (+1 bp). This portion of the 5'-flanking region has neither a TATA nor a CCAAT box, is GC-rich but has no GC box motif, and has features of promoters seen in housekeeping genes. Chimeras containing 2.2 kb of the 5'-flanking region and deletion analyses using the chloramphenicol acetyltransferase gene indicated that a "minimal" region, exhibiting promoter activity and tissue specificity, is located between nucleotides -296 and -221, when transfected into vascular smooth muscle cells. Gel mobility shift assay and Southwestern blotting suggested that approximately 30- and approximately 28-kDa nuclear proteins specifically bind to this region. Rapid amplification of the 3'-end of the cDNA showed that the major transcript terminates 442 bp downstream of the stop codon, in agreement with the mRNA size (2.1 kb). This study demonstrated a distinctive feature in the structural organization of the AVP-oxytocin receptor family genes, and characterization of the 5'-flanking region reported here will lead to a better understanding of the mechanism of transcriptional regulation of the rat V1a AVP receptor gene.

Characterization of glucocorticoid response element of rat angiotensin II type 1A receptor gene

The responsiveness of the rat angiotensin II type 1a and type 1b receptor (AT1a-R and AT1b-R) genes to glucocorticoid was examined in rat vascular smooth muscle cells (VSMCs) and the glucocorticoid response element (GRE) of the AT1a-R gene was characterized. Glucocorticoid induced an increase in AT1a-R mRNA levels, whereas AT1b-R mRNA levels were unaffected. The nuclear run-off assay indicated that the transcription of the AT1a-R gene, but not that of the AT1b-R gene, was increased by glucocorticoid. The mRNA stability of AT1a-R was unchanged by glucocorticoid. Promoter/chrolamphenicol acetyltransferase reporter analysis demonstrated that the 5'-flanking region of the AT1a-R gene was functional in rat VSMCs and established that the GRE motif between -770 to -756 could confer glucocorticoid responsiveness on the AT1a-R gene.

Reversible left ventricular dysfunction associated with Guillain-Barré syndrome--an expression of catecholamine cardiotoxicity?

The patient was a 76-year-old female who had a history of Guillain-Barré syndrome 3 years previously; ST-segment elevation was noted in association with reversible left ventricular dysfunction. Left ventrioculogram and coronary angiograms were normal and ergonovine test was negative during the chronic period of Guillain-Barré syndrome. She was hospitalized again due to the recurrence of Guillain-Barré syndrome. Two days later, ST-segment elevation in leads V2 through V5 prompted us to perform cardiac catheterization, although she did not complain of any chest symptoms. A large akinetic area was found mainly around the apex on left ventriculography, despite the lack of coronary stenoses. Peak creatine kinase and C-reactive protein were 400 IU/ml and 3.5 mg/dl, respectively. Left ventricular dysfunction was normalized within one week. During the acute phase of the cardiac episode, plasma norepinephrine and epinephrine were 1340 pg/ml and 112 pg/ml, respectively. I123 metaiodobenzyl-guanidine myocardial scintigram 3 weeks after the episode showed an extensive apical defect which was improved markedly 3 months later. We think that this reversible left ventricular dysfunction was due to the synergistic toxic effect of mildly increased catecholamine and transiently damaged sympathetic nerve endings in the myocardium, presumably due to Guillain-Barré syndrome.

Markedly enlarged right atrium associated with physical signs of tricuspid regurgitation--a cause of congestive heart failure in the elderly

We retrospectively examined 8 patients who had classical physical signs of tricuspid regurgitation associated with congestive heart failure, the cause of which was not identified by echocardiography. Exclusion criteria were as follows; 1) peak velocity of tricuspid regurgitation greater than 3 m/sec, 2) disturbance of left ventricular wall motion, 3) severe mitral regurgitation and/or aortic regurgitation by color Doppler echocardiography, and 4) structural abnormalities of tricuspid and mitral valve complexes. The subjects had a mean age of 81 years and all showed atrial fibrillation without tachycardia. Radiocardiography showed no significant left-to-right shunt. Two-dimensional echocardiography showed a markedly enlarged right atrium and slight enlargement of the right ventricle in all patients. A signal of tricuspid regurgitation was seen throughout the markedly enlarged right atrium on color Doppler echocardiography. Although neither hypoxemia nor hypercapnea were found in any of the patients, pulmonary function tests done in 6 patients were all abnormal. In chest x-ray films, 6 of the patients showed evidence of marked protrusion of the right heart border progressing over the course of several years. Right atrial enlargement due to both long-standing atrial fibrillation and presumably, to right ventricular diastolic dysfunction caused by aging made the tricuspid valve annuls annulus dilate to produce tricuspid regurgitation. In addition, concomitant mild lung disease produced a vicious cycle which led to more severe tricuspid regurgitation resulting in severe congestive heart failure. This pathophysiology can be a cause of congestive heart failure in the elderly.

Multiple peripheral pulmonary artery branch stenosis in a young Japanese girl with systemic hypertension

We present a 16-year-old girl with pulmonary hypertension due to multiple pulmonary artery obstructions and stenoses. Juvenile hypertension was complicated by 75 percent stenosis of the left renal artery. Similar pulmonary angiographic findings 1 year later and no sign of inflammation in the following year suggest that this condition is congenital in origin.

Purification and properties of Saccharomyces cerevisiae cystathionine beta-synthase

Cystathionine beta-synthase (beta-CTSase), which catalyses cystathionine synthesis from serine and homocysteine, was purified to homogeneity from Saccharomyces cerevisiae. The molecular mass of the enzyme was estimated to be 235 kDa by gel filtration and 55 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, indicating that it is a homotetramer. The N-terminal amino acid sequence of the enzyme perfectly coincided with that deduced from the nucleotide sequence of CYS4, except for the absence of initiation The purified beta-CTSase catalysed cysteine synthesis from serine (or O-acetylserine) and H2S. From this finding, we discuss the multifunctional nature and evolutionary divergence of S-metabolizing enzymes.