Arterial stiffness of the aorta and iliofemoral artery and their responses to nitroglycerin administration in myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits

OBJECTIVES

The role of hypercholesterolemia in arterial stiffness, which usually reflects the progression of atherosclerosis has not been fully investigated. To clarify the meaning of arterial stiffness in hypercholesterolemia, we evaluated arterial stiffness in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits by using new arterial stiffness indices of the aorta and common iliac to femoral artery. The new arterial stiffness indices of both arteries were determined by the application of the theory of cardio-ankle vascular index (CAVI) to the aorta (aBeta) and ilio-femoral artery (ifBeta). Furthermore, the responses of both indices to nitroglycerin (NTG) administration were compared between WHHHMI and normal rabbits.

DESIGN AND METHODS

aBeta and ifBeta of WHHLMI and normal rabbits were measured under anesthesia. Pulse wave velocity in the whole aorta (aPWV) and ilio-femoral artery (ifPWV), blood pressure, and other parameters were measured before and after administration of NTG (50-120 μg/kg/min) every 1 for 5 min.

RESULTS

Atherosclerotic lesions were observed in the aorta, but a little in the ilio-femoral artery in WHHLMI rabbits. Compared with normal rabbits, aBeta was significantly higher, but ifBeta was lower in WHHLMI rabbits. When NTG was administered, ifBeta decreased significantly in both groups; however, aBeta increased in normal rabbits, but remained unchanged in WHHIMI rabbits.

CONCLUSION

These findings suggested that hereditary hypercholesterolemia in rabbits did not uniformly enhance arterial stiffness in elastic artery and muscular artery. The responses to NTG were also different between two arteries. The mechanism of these different responses needs further studies.

Approach for Elucidating the Molecular Mechanism of Epithelial to Mesenchymal Transition in Fibrosis of Asthmatic Airway Remodeling Focusing on Cl- Channels

Airway remodeling caused by asthma is characterized by structural changes of subepithelial fibrosis, goblet cell metaplasia, submucosal gland hyperplasia, smooth muscle cell hyperplasia, and angiogenesis, leading to symptoms such as dyspnea, which cause marked quality of life deterioration. In particular, fibrosis exacerbated by asthma progression is reportedly mediated by epithelial-mesenchymal transition (EMT). It is well known that the molecular mechanism of EMT in fibrosis of asthmatic airway remodeling is closely associated with several signaling pathways, including the TGF-β1/Smad, TGF-β1/non-Smad, and Wnt/β-catenin signaling pathways. However, the molecular mechanism of EMT in fibrosis of asthmatic airway remodeling has not yet been fully clarified. Given that Cl- transport through Cl- channels causes passive water flow and consequent changes in cell volume, these channels may be considered to play a key role in EMT, which is characterized by significant morphological changes. In the present article, we highlight how EMT, which causes fibrosis and carcinogenesis in various tissues, is strongly associated with activation or inactivation of Cl- channels and discuss whether Cl- channels can lead to elucidation of the molecular mechanism of EMT in fibrosis of asthmatic airway remodeling.

Estimation of Central Systolic Blood Pressure from Peripheral Pressure Waves using a Novel Second Systolic Pressure-Based Method in Normal and Heritable Hypercholesterolemic Rabbits

AIM

Central systolic blood pressure (cSBP) was closely related to hypertension-related organ damage rather than peripheral systolic blood pressure (pSBP). We aimed to estimate cSBP from pSBP without generalized transfer function in normal and Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits aged 12 months.

METHODS

Two catheter-tip transducers were advanced into the ascending aorta (AA) and distal end of the right brachial artery (Br) through the right common carotid and right radial arteries, respectively, under pentobarbital anesthesia. Pressure waves in response to the intravenous administration of angiotensin II and sodium nitroprusside were simultaneously recorded in AA and Br under regular cardiac pacing.

RESULTS

The first (pSBP) and second peaks (pSBP2) of the brachial blood pressure and their average (pSBPm) were significantly correlated with cSBP, despite Murgo's wave pattern of central pressure waves in both rabbit groups. In Bland-Altman plot and its modification as a function of the peripheral augmentation index (pAI) analyses, the differences between pSBP and cSBP decreased, and those between pSBP2 and cSBP increased significantly in their average- or pAI-dependent manner, with undeniable mean biases in both rabbit groups. When the same analyses for SBPm were performed instead, the mean bias was around zero, with reduced variance in the two rabbit groups. The observed pressure or pAI-dependent systematic biases for pSBP and pSBP2 disappeared, representing the precise feature of pSBPm as a cSBP estimate.

CONCLUSIONS

We conclude that pSBPm could be more precise than pSBP2 as a cSBP estimate, irrespective of blood pressure levels, pAI, or the presence of atherosclerosis.

Opposing Responses of the Calcium Channel Blocker Nicardipine to Vascular Stiffness in the Elastic and Muscular Arteries in Rabbits

AIM

The cardio-ankle vascular index (CAVI) consists of intrinsic and functional arterial stiffness mainly regulated by vasoactive compounds. A new stiffness index of the aorta (aBeta) and iliac-femoral arteries (ifBeta) was determined by applying the CAVI theory to the whole aorta and iliac-femoral arteries. We investigated the changes in aBeta and ifBeta in response to decreased blood pressure (BP) induced by the Ca2＋ channel blocker nicardipine to elucidate the involvement of Ca2＋ in aBeta and ifBeta.

METHODS

Pressure waves at the origin of the aorta (oA), distal end of the abdominal aorta (dA), and left femoral artery (fA) as well as flow waves at the oA were simultaneously recorded before and after the infusion of nicardipine (50 µg/kg/min) for 2 min in 12 male rabbits under pentobarbital anesthesia. Beta was calculated using the following formula: Beta=2ρ / PP×ln (SBP / DBP)×PWV2, where ρ, SBP, DBP, and PP denote blood density and systolic, diastolic, and pulse pressures, respectively. aBeta, ifBeta, and aortic-iliac-femoral Beta (aifBeta) were calculated using aPWV, ifPWV, and aifPWV, respectively.

RESULTS

SBP, mean arterial pressure (MAP), DBP, and total peripheral vascular resistance significantly decreased during the administration of nicardipine, whereas cardiac output significantly increased. aBeta and ifBeta significantly increased and decreased, respectively, whereas aifBeta did not change despite the decrease in BP. ifBeta and aBeta positively and negatively correlated with BP, respectively, whereas aifBeta did not correlate with SBP.

CONCLUSIONS

There were contradictory arterial responses to nicardipine between the elastic and muscular arteries. Unknown vasoconstriction mechanisms that are not involved in Ca2＋ influx may function in the aorta in response to decreased BP.

Cesium Treatment Depresses Glycolysis Pathway in HeLa Cell

BACKGROUND/AIMS

Cesium (Cs) is an alkali metal element that is of no essential use for humans; it has no known beneficial function that is verified by clinical research. When used as an alternative cancer therapy, it even causes toxicity in high doses. Thus, before using Cs as treatment in clinical settings, it is important to clearly determine its biological effects on cells. However, Cs was found to suppress the proliferation of human cervical cancer cells in a dose-dependent manner, and it was assumed that Cs inhibits the glycolysis pathway. In this study, we clearly determined the step of the glycolysis pathway that is affected by Cs.

METHODS

The glycolytic enzyme expressions, activities, and metabolite concentrations in HeLa cells were measured by PCR, western blotting, and enzymatic methods, after treating the cells with Cs for 3 days.

RESULTS

Cs treatment decreased transcriptional and expression levels of hexokinase, glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase (PK), and lactate dehydrogenase and the activity of PK. Analysis of glycolysis pathway metabolites revealed that Cs treatment reduces lactate level and increases the level of nicotinamide adenine dinucleotide (oxidized form, NAD⁺); however, it did not affect the levels of pyruvate and nicotinamide adenine dinucleotide (reduced form, NADH). Increase of the [NAD⁺]/[NADH] ratio and decrease of the [lactate]/[pyruvate] ratio indicate that Cs treatment inhibits the aerobic glycolysis pathway.

CONCLUSION

Cs treatment inhibits PK activity and increases the [NAD⁺]/[NADH] ratio. Hence, Cs has been determined to inhibit glycolysis, especially the aerobic glycolysis pathway. These results suggest that suppression of HeLa cell proliferation following Cs treatment was caused by inhibition of aerobic glycolysis by Cs.

The deletion of glucagon-like peptide-1 receptors expressing neurons in the dorsomedial hypothalamic nucleus disrupts the diurnal feeding pattern and induces hyperphagia and obesity

BACKGROUND

Feeding rhythm disruption contributes to the development of obesity. The receptors of glucagon-like peptide-1 (GLP-1) are distributed in the wide regions of the brain. Among these regions, GLP-1 receptors (GLP-1R) are expressed in the dorsomedial hypothalamic nucleus (DMH) which are known to be associated with thermogenesis and circadian rhythm development. However, the physiological roles of GLP-1R expressing neurons in the DMH remain elusive.

METHODS

To examine the physiological role of GLP-1R expressing neurons in the DMH, saporin-conjugated exenatide4 was injected into rat brain DMH to delete GLP-1R-positive neurons. Subsequently, locomotor activity, diurnal feeding pattern, amount of food intake and body weight were measured.

RESULTS

This deletion of GLP-1R-positive neurons in the DMH induced hyperphagia, the disruption of diurnal feeding pattern, and obesity. The deletion of GLP-1R expressing neurons also reduced glutamic acid decarboxylase 67 and cholecystokinin A receptor mRNA levels in the DMH. Also, it reduced the c-fos expression after refeeding in the suprachiasmatic nucleus (SCN). Thirty percent of DMH neurons projecting to the SCN expressed GLP-1R. Functionally, refeeding after fasting induced c-fos expression in the SCN projecting neurons in the DMH. As for the projection to the DMH, neurons in the nucleus tractus solitarius (NTS) were found to be projecting to the DMH, with 33% of those neurons being GLP-1-positive. Refeeding induced c-fos expression in the DMH projecting neurons in the NTS.

CONCLUSION

These findings suggest that GLP-1R expressing neurons in the DMH may mediate feeding termination. In addition, this meal signal may be transmitted to SCN neurons and change the neural activities.

Dysfunction of Cl- channels promotes epithelial to mesenchymal transition in oral squamous cell carcinoma via activation of Wnt/β-catenin signaling pathway

Oral squamous cell carcinoma (OSCC) is a highly aggressive carcinoma with a high incidence of recurrence and distant metastasis. However, the mechanism of epithelial to mesenchymal transition (EMT) during tumor progression and metastasis in OSCC has not yet been fully elucidated. It is well known that the Cl^- channel controls cell volume and activates several signaling pathways for cell differentiation. The aim of the present study was to investigate the role of the Cl^- channel on EMT in the OSC 20 cell line, which is an OSCC line. OSC-20 cells were cultured with low serum medium containing a Cl^- channel blocker NPPB. Morphological changes, gene expression, immunoreactivity, cell volume, and signaling pathway of the NPPB-treated OSC-20 cells were evaluated. The NPPB-treated OSC-20 cells showed typical morphology of mesenchymal cells. The expression levels of the epithelial marker E-cadherin in the NPPB-treated OSC-20 cells were lower than those of the untreated and TGF-β1-treated OSC-20 cells. On the other hand, mesenchymal markers such as vimentin, ZEB1, and Snail, in the NPPB-treated OSC-20 cells were higher than those in the untreated and TGF-β1-treated OSC-20 cells. Furthermore, a large number of vimentin-positive cells also appeared in the NPPB-treated OSC-20 cells. Additionally, the cell volume of these cells was significantly increased compared to that of the untreated and TGF-β1-treated cells. Interestingly, NPPB did not activate the TGF-β/smad signaling pathway, but activated the Wnt/β-catenin signaling pathway. These results suggest that Cl^- channel dysfunction promoted EMT via activation of the Wnt/β-catenin signaling pathway in OSCC.

Different Responses of Arterial Stiffness between the Aorta and the Iliofemoral Artery during the Administration of Phentolamine and Atenolol in Rabbits

Aim: The mechanism underlying the stiffness of the aorta and iliofemoral artery that is required to maintain blood pressure (BP) is unclear. A new stiffness index of the aorta (aBeta) and iliac-femoral arteries (ifBeta) was defined by applying the cardio-ankle vascular index (CAVI). We compared changes in stiffness of the two arteries in response to reduced BP, due to the non-selective α adrenergic blocker phentolamine and the β ₁ adrenergic blocker atenolol, in rabbits.

Methods: Pressure waves at the origin (oA) and distal ends of the aorta (dA) and the distal end of the left femoral artery (fA) were recorded simultaneously using three pressure sensors in 25 anesthetized rabbits. Phentolamine (50 µg/kg/min) and atenolol (10 mg/kg/min) were infused for 2 min. The pulse wave velocity (PWV) in each artery was determined; aBeta, ifBeta, and whole Beta (aifBeta) were calculated by the following formula; Beta=2ρ/PP×ln(SBP/DBP)×PWV ² (ρ: blood density; SBP, SBP, and PP: systolic, diastolic, and pulse pressures, respectively).

Results: SBP and DBP at oA, dA, and fA decreased by the administration of phentolamine and atenolol, with and without decreased total peripheral vascular resistance. After phentramine infusion, cardiac output (CO), aBeta, and aifBeta increased, while ifBeta decreased. After infusion of atenolol, CO decreased, while aBeta, ifBeta, and aifBeta remained unchanged.

Conclusion: The contradictory reactions of aBeta and ifBeta to phentolamine suggest that the stiffness of the aorta and ilio-femoral artery is regulated separately during decreased BP induced by phentolamine, but not by atenolol.

Cesium suppresses fibroblast proliferation and migration

During wound healing, fibroblasts proliferate from the margin, and migrate into the provisional matrix where they differentiate into myofibroblasts resulting in wound contraction; however, fibroblasts are hyperproliferative during chronic tissue damage. We previously reported that cesium chloride inhibited a human cancer cell proliferation; therefore, cesium is also presumed to suppress fibroblast proliferation. We here investigated the effects of cesium chloride on the proliferation and migration of murine embryotic fibroblast cells, NIH/3T3 cells. Cultured NIH/3T3 cells with 0-10 mM sodium and cesium chloride were counted using trypan blue dye-exclusion method, then cell growth and viability were evaluated. The percentage of wound closure was calculated by scratch assay. The number of the cells was decreased by application of 1-10 mM cesium in a dose-dependent manner, whereas the viability of the cells was unchanged. The treatment with 3-10 mM cesium inhibited the proliferation rate and % of wound closure compared with controls. These results suggested that cesium inhibits the proliferation and migration of fibroblast cells. This study indicates a possible therapeutic role of cesium chloride in the treatment of wound healing and fibrosis.

Negative chronotropic and inotropic effects of lubiprostone on iPS cell-derived cardiomyocytes via activation of CFTR

Background

Lubiprostone (LBP) is a novel chloride channel opener that has been reported to activate chloride channel protein 2 (ClC-2) and cystic fibrosis transmembrane conductance regulator (CFTR). LBP facilitates fluid secretion by activating CFTR in the intestine and is used as a drug for treating chronic constipation. While ClC-2 and CFTR expression has been confirmed in cardiomyocytes (CMs), the effect of LBP on CMs has not yet been investigated. Thus, the present study aimed to investigate the effect of LBP on CMs using mouse-induced pluripotent stem (iPS) cell-derived CMs (iPS-CMs).

Methods

We induced mouse iPS cells into CMs through embryoid body (EB) formation. We compared the differentiated cells to CMs isolated from adult and fetal mice using gene expression, spontaneous beating rate, and contraction ratio analyses.

Results

Gene expression analysis revealed that, in the iPS-CMs, the mRNA expression of the undifferentiated cell markers Rex1 and Nanog decreased, whereas the expression of the unique cardiomyocyte markers cardiac troponin I (cTnI) and cardiac troponin T (cTNT), increased. Immunostaining showed that the localization of cTnI and connexin-43 in the iPS-CMs was similar to that in the primary fetal CMs (FCMs) and adult CMs (ACMs). LBP decreased the spontaneous beating rate of the iPS-CMs and FCMs, and decreased the contraction ratio of the iPS-CMs and ACMs. The reduction in the beating rate and contraction ratio caused by LBP was inhibited by glycine hydrazide (GlyH), which is a CFTR inhibitor.

Conclusion

These results suggest that LBP stimulates CFTR in CMs and that LBP has negative chronotropic and inotropic effects on CMs. LBP may be useful for treating cardiac diseases such as heart failure, ischemia, and arrhythmia.

Airway regeneration using iPS cell-derived airway epithelial cells with Cl- channel function

induced pluripotent stem (iPS) cells can be differentiated into various cell types, including airway epithelial cells, since they have the capacity for self-renewal and pluripotency. Thus, airway epithelial cells generated from iPS cells are expected to be potent candidates for use in airway regeneration and the treatment of airway diseases such as cystic fibrosis (CF). Recently, it was reported that iPS cells can be differentiated into airway epithelial cells according to the airway developmental process. These studies demonstrate that airway epithelial cells generated from iPS cells are equivalent to their in vivo counterparts. However, it has not been evaluated in detail whether these cells exhibit physiological functions and are fully mature. Airway epithelial cells adequately control water volume on the airway surface via the function of Cl⁻ channels. Reasonable environments on the airway surface cause ciliary movement with a constant rhythm and maintain airway clearance. Therefore, the generation of functional airway epithelial cells/tissues with Cl⁻ channel function from iPS cells will be indispensable for cell/tissue replacement therapy, the development of a reliable airway disease model, and the treatment of airway disease. This review highlights the generation of functional airway epithelial cells from iPS cells and discusses the remaining challenges to the generation of functional airway epithelial cells for airway regeneration and the treatment of airway disease.

The Cytotoxic Effects of Geranylgeranylacetone Are Attenuated in the High-Glucose Condition

Geranylgeranylacetone (GGA) has been used as an antiulcer drug and also is known as inducer of heat shock protein 70 that has cytoprotective effects especially in hyperglycemic condition. In contrast, cytotoxicity of GGA has also been reported. Some studies have reported that GGA suppresses cell growth and induces apoptosis in cell models of human leukemia, ovarian carcinoma, and colon cancer in vitro. Therefore, the aim of this study was to determine whether GGA can have a cytotoxic effect on a human cervical cancer cell line (HeLa), human colorectal adenocarcinoma cells (Caco-2), and human embryonic kidney cells 293 (HEK) in normal-glucose and high-glucose environments (NG and HG, respectively). The results showed that 100 μM GGA inhibited proliferation of HeLa cells only in NG environment despite inhibiting proliferation of Caco-2 and HEK cells regardless of glucose concentration. Cell viability assay revealed that GGA decreased viability of HeLa, Caco-2, and HEK cells only in NG environment. Flow cytometric analyses revealed that the type of cell death was a combination of necrosis and apoptosis. Our study revealed that difference in cytotoxicity of GGA is influenced by glucose condition. The cytotoxic effects of GGA are attenuated in the HG condition. Since both cytotoxic and cytoprotective effects are reported about GGA, further research is needed about the mechanism of the cytotoxic effects.

Cl- channels regulate lipid droplet formation via Rab8a expression during adipocyte differentiation

Several studies have shown that Cl^- channels regulate the differentiation of some cell types. Thus, we investigated the role of Cl^- channels on adipocyte differentiation using adipose tissue-derived stem cells (ASCs) and Cl^- channel blocker. We induced rabbit ASCs into adipocytes using Cl^- channel blocker. The expression levels of adipocyte markers were no significant difference between the cells treated with a Cl^- channel blocker NPPB and untreated cells. However, when the cells were treated with NPPB, lipid droplets (LDs) sizes decreased compared with the untreated control. Interestingly, the expression levels of Rab8a, which is known as a regulator of LD fusion, were also decreased in the cells treated with NPPB. Other Cl^- channel blockers, DIDS and IAA-94, also inhibited large LDs formation and Rab8a expression. These results demonstrate that Cl^- channels do not regulate the adipocyte differentiation, but do regulate the LDs formation via Rab8a expression.Abbreviations: ASCs: adipose tissue-derived stem cells; LDs: lipid droplets; RUNX2: runt-related transcription factor 2; CFTR: cystic fibrosis transmembrane conductance regulator; TG: triacylglycerol; FA: fatty acid; GLUT4: glucose transporter type 4; ER: endoplasmic reticulum; ADRP: adipose differentiation-related protein; TIP47: tail-interacting protein of 47 kD; HSL: hormone sensitive lipase; PBS: phosphate-buffered saline; DMEM: Dulbecco's modified Eagle Medium; FBS: fetal bovine serum; SMA: smooth muscle actin; FAS: fatty acid synthase; ZONAB: ZO-1 associated nucleic acid binding protein; PPAR-γ: peroxisome proliferator-activated receptor-γ; C/EBPα: CCAAT/enhancer binding protein α; CE: cholesteryl ester; V-ATPase: vacuolar H⁺ ATPase.

Functional characterization of various channel-expressing central airway epithelial cells from mouse induced pluripotent stem cells

Functional central airway epithelial cells (CAECs) from induced pluripotent stem cells (iPSCs) are an attractive potential cell source for central airway regeneration. The central airway epithelium, such as the tracheal epithelium, is composed of ciliated cells, goblet cells, and basal cells and has physiologically important functions such as the regulation of water volume on the airway surface by Cl^- and water channels and the elimination of particles inhaled from the external environment by ciliary movement. Previous work from our group and from other research groups has reported the generation of airway epithelial cells from iPSCs. However, it remains unclear whether iPSC-derived CAECs express the various channels that are required for the regulation of water volume on the airway surface and whether these channels function properly. In this study, we generated CAECs from iPSCs supplemented with activin and bFGF using air-liquid interface culture. We then evaluated the physiological functioning of the iPSC-derived CAECs by examining the gene expression and transport functions of Cl ^- channels using a halide ion-sensitive yellow fluorescent protein and ciliary movement. Reverse-transcription polymerase chain reaction and immunohistochemistry indicated that various channel markers such as cystic fibrosis transmembrane conductance regulator (CFTR) and aquaporin (AQP) were present in iPSC-derived CAECs. Furthermore, the transport functions of Cl ^- channels and CFTR were successfully confirmed. Finally, ciliary movement was measured, and a ciliary beating frequency (CBF) of approximately 10 Hz was observed. These results demonstrate that CAECs generated by our method have physiological functions similar to those of native CAECs.

Nesfatin-1 inhibits voltage gated K+ channels in pancreatic beta cells

The anorexigenic neuropeptide NEFA/nucleobindin 2 (NUCB2)/nesfatin-1-containing neurons are distributed in the brain regions involved in feeding regulation. In spite of the growing knowledge of its physiological functions through extensive studies, its molecular mechanism of reaction, including its receptor, remains unknown. NUCB2/nesfatin-1 is also involved in various peripheral regulations, including glucose homeostasis. In pancreatic beta-cells, NUCB2/nesfatin-1 is reported to enhance glucose-stimulated insulin secretion (GSIS) but its exact mechanism remains unknown. To clarify this mechanism, we measured the effect of nesfatin-1 on the electrical activity of pancreatic beta-cells. Using mouse primary beta cells, we measured changes in the ATP-sensitive K⁺ (K_ATP) channel current, the voltage-gated K⁺ (Kv) channel current, and insulin secretion upon application of nesfatin-1. Nesfatin-1 inhibited the Kv channel, but K_ATP channel activity was unaffected. Nesfatin-1 enhanced insulin secretion to a same level as Kv channel blocker tetraethylammonium (TEA). The effect was not further enhanced when nesfatin-1 and TEA were applied simultaneously. The inhibition binding assay with [¹²⁵I]nesfatin-1 in Kv2.1 channels, major contributor of Kv current in beta cell, expressing HEK239 cells indicated the binding of nesfatin-1 on Kv2.1 channel. Because Kv channel inhibition enhances insulin secretion under high glucose conditions, our present data suggest a possible mechanism of nesfatin-1 on enhancing GSIS through regulation of ion channels rather than its unidentified receptor.

Heparin cross-linked collagen sponge scaffolds improve functional regeneration of rat tracheal epithelium

Tracheal epithelial cells maintain airway homeostasis by mediating mucociliary clearance. Following tracheal reconstruction, timely epithelial regeneration is required to prevent respiratory compromise and infectious diseases. To achieve rapid tracheal epithelial regeneration, a heparin cross-linked collagen sponge containing fibroblast growth factor-2 (FGF-2) was prepared as a graft for tracheal reconstruction. The heparin cross-linked sponge exhibited a high FGF-2 retaining capacity, and tracheal epithelial and mesenchymal cells cultured in this sponge containing FGF-2 showed high proliferative capacities. Subsequently, heparin-free collagen sponge scaffolds (C/F scaffold) and collagen sponge scaffolds cross-linked with 10 μg/ml heparin retained FGF-2 (C/H10/F scaffold), and were transplanted into rats with tracheal defects. Invasion of both epithelial and non-epithelial cells was greater in rats treated with the C/H10/F scaffold at 1 week post-transplantation than in rats treated with the C/F scaffold. Moreover, at 2 weeks after transplantation, improved cilia formation was observed in the C/H10/F scaffold group, with higher motility and more potent posterior-anterior flow generation than in the C/F scaffold group. These results suggest that heparin improves functional regeneration of tracheal epithelium. Copyright © 2017 John Wiley & Sons, Ltd.

Carrageenan delays cell cycle progression in human cancer cells in vitro demonstrated by FUCCI imaging

BACKGROUND

Carrageenan is a sulfated polysaccharide that exists in red seaweeds recently shown to have anticancer properties. Previous findings show various effects of carrageenan suppressing tumor cell growth. One of the hallmarks of cancer is uncontrolled proliferation, a consequence of loss of normal cell-cycle control, that underlies tumor growth. Recently there is an increasing interest in potential anticancer agents that affect cell cycle in cancer cells. Thus, in this study we investigated the effects of carrageenan on the tumor cell cycle.

METHODS

Using human cervical carcinoma cells (HeLa) cells as and human umbilical vein endothelial cells (HUVEC), the cytotoxic effects of kappa carrageenan (k-CO) and lambda carrageenan (λ-CO) at the concentrations of 250-2500 μg/mL were observed. Cell viability was determined using the MTT assay while cell death rates were determined using staining with calcein-AM/propidium iodide. Cell-cycle profile and progression were demonstrated with HeLa cells expressing FUCCI (fluorescence ubiquitination-based cell-cycle indicator) probes (HeLa-FUCCI).

RESULTS

Carrageenan had no significant effect on HUVEC (normal cells). In contrast both forms of carrageenan were cytotoxic towards HeLa cells (cancer cells). Furthermore, according to cell-cycle analysis with FUCCI cells, the cell cycle of HeLa cells was delayed in specific phases due to different carrageenan treatments.

CONCLUSION

Considering these results, it could be suggested that carrageenan affects the cell-cycle of HeLa cells not only by arresting the cell cycle in specific phases but also by delaying the time needed for the cell to progress through the cell cycle. Additionally, different types of carrageenans have different effects on cell cycle progression. This effect of carrageenan towards cancer cells could possibly be developed into a tumor cell-specific anticancer agent.

Tissue Engineering for Regeneration of the Tracheal Epithelium

Objectives:

The slowness of epithelialization on the artificial trachea that has been successfully used in humans is a problem. The purpose of this study was to develop a way to regenerate the epithelium on the surface of this artificial trachea.

Methods:

In an in vitro study, isolated rat tracheal epithelial cells were seeded on a collagenous gel that was stratified on a collagenous sponge. Histologic and immunohistochemical examinations were made. In an in vivo study, we transplanted grafts with green fluorescent protein–positive tracheal epithelial cells onto the tracheal defects of normal rats. At 3, 7, 14, and 30 days after the operation, histologic and immunohistochemical examinations were made.

Results:

In the in vitro study, the 3 layers — the epithelium, gel, and sponge — could be observed. The epithelium expressed cytokeratin 14, cytokeratin 18, and occludin. In the in vivo study, the artificial trachea was covered with epithelium at 3 days after operation, and then the epithelium differentiated from single- or double-stratified squamous epithelium into columnar ciliated epithelium. Green fluorescent protein–positive cells were found 3 days after operation.

Conclusions:

We believe that the method used in our experiment is an effective way to regenerate the epithelium on the surface of an artificial trachea. With further experimentation, this method should be suitable for clinical application.

Optimal bovine collagen concentration to achieve tracheal epithelial coverage of collagen sponges

OBJECTIVES/HYPOTHESIS

Artificial tracheas prepared using a collagen sponge and polypropylene mesh have been implanted in patients who received tracheal resections, but epithelialization in the reconstructed area is slow. We determined the optimal bovine atelocollagen concentration necessary for the rapid and complete tracheal epithelial coverage of collagen sponge implants.

STUDY DESIGN

Preliminary animal experiment.

METHODS

Collagen sponges were prepared using lyophilizing 0.5%, 0.7%, and 1.0% atelocollagen solutions (0.5%, 0.7%, and 1.0% sponges) and were analyzed using scanning electron microscopy. Partial tracheal defects were prepared in rabbits and reconstructed using sponges. Epithelial regeneration in the reconstructed area was evaluated by endoscopic, histological, and scanning electron microscope analyses.

RESULTS

All sponges had a membranous structural framework, and numerous fibrous structures filled the spaces within the framework in the 0.5% sponges. The membranous structure in the 0.7% sponges branched at many points, and intermembrane spaces were frequently observed. Conversely, the membranous structure in the 1.0% sponges was relatively continuous, thick, and closely arranged. Two weeks after implantation, tracheal defects were entirely covered with epithelium in two of the four and three of the four of the 0.5% and 0.7% sponge-implanted rabbits, respectively. The collagen sponges remained exposed to the tracheal lumen in four of the four rabbits in the 1.0% sponge group. Ciliogenesis in the center of the epithelialized region was detected only in the 0.7% sponge group.

CONCLUSION

Collagen sponges prepared from various concentrations of bovine atelocollagen have different structures. Complete epithelial coverage was achieved in more rabbits implanted with sponges prepared using the 0.7% bovine atelocollagen solution than in those implanted with sponges prepared from the 0.5% and 1.0% solutions.

LEVEL OF EVIDENCE

NA Laryngoscope, 126:E396-E403, 2016.

Potential of laryngeal muscle regeneration using induced pluripotent stem cell-derived skeletal muscle cells

Conclusion Induced pluripotent stem (iPS) cells may be a new potential cell source for laryngeal muscle regeneration in the treatment of vocal fold atrophy after recurrent laryngeal nerve paralysis. Objectives Unilateral vocal fold paralysis can lead to degeneration, atrophy, and loss of force of the thyroarytenoid muscle. At present, there are some treatments such as thyroplasty, arytenoid adduction, and vocal fold injection. However, such treatments cannot restore reduced mass of the thyroarytenoid muscle. iPS cells have been recognized as supplying a potential resource for cell transplantation. The aim of this study was to assess the effectiveness of the use of iPS cells for the regeneration of laryngeal muscle through the evaluation of both in vitro and in vivo experiments. Methods Skeletal muscle cells were generated from tdTomato-labeled iPS cells using embryoid body formation. Differentiation into skeletal muscle cells was analyzed by gene expression and immunocytochemistry. The tdTomato-labeled iPS cell-derived skeletal muscle cells were transplanted into the left atrophied thyroarytenoid muscle. To evaluate the engraftment of these cells after transplantation, immunohistochemistry was performed. Results The tdTomato-labeled iPS cells were successfully differentiated into skeletal muscle cells through an in vitro experiment. These cells survived in the atrophied thyroarytenoid muscle after transplantation.

Regeneration of tracheal epithelium using mouse induced pluripotent stem cells

Conclusion The findings demonstrated the potential use of induced pluripotent stem cells for regeneration of tracheal epithelium. Objective Autologous tissue implantation techniques using skin or cartilage are often applied in cases of tracheal defects with laryngeal inflammatory lesions and malignant tumor invasion. However, these techniques are invasive with an unstable clinical outcome. The purpose of this study was to investigate regeneration in a tracheal defect site of nude rats after implantation of ciliated epithelium that was differentiated from induced pluripotent stem cells. Method Embryoid bodies were formed from mouse induced pluripotent stem cells. They were cultured with growth factors for 5 days, and then cultured at the air-liquid interface. The degree of differentiation achieved prior to implantation was determined by histological findings and the results of real-time polymerase chain reaction. Embryoid bodies including ciliated epithelium were embedded into collagen gel that served as an artificial scaffold, and then implanted into nude rats, creating an 'air-liquid interface model'. Histological evaluation was performed 7 days after implantation. Results The ciliated epithelial structure survived on the lumen side of regenerated tissue. It was demonstrated histologically that the structure was composed of ciliated epithelial cells.

Povidone-iodine-induced cell death in cultured human epithelial HeLa cells and rat oral mucosal tissue

Although povidone-iodine (PVP-I) has been used as a gargle since 1956, its effectiveness and material safety have been remained controversial. The aim of this study was to investigate the toxicity of PVP-I to epithelial cells in a concentration range significantly lower than that used clinically. Study design was in vitro laboratory investigations and in vivo histological and immunologic analysis. We examined the effects of PVP-I at concentrations of 1 × 10(-2) to 1 × 10(3) μM and 1 × 10(-4) to 1 × 10 μM on HeLa cells as a model of epithelial cells and rat oral mucosa, respectively, after 1 or 2 days of exposure. Annexin V/FLUOS was used to distinguish live, apoptotic and necrotic cells. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method was also used to observe whether apoptotic epithelial cells exist in rat oral mucosa after 1 day of exposure of PVP-I. HeLa cells developed concentration-dependent cytotoxicity, and epithelium of rat oral mucosa was thinned in a concentration-dependent manner. HeLa cell apoptosis increased after 1 × 10(0) μM of PVP-I exposure for 2 days. In the TUNEL method, many apoptotic epithelial cells were observed in the rat oral mucosa after 1 day of exposure to diluted 1 × 10(-2) μM of PVP-I, but minimal apoptotic epithelial cells were observed using 1 × 10(-3) μM of PVP-I. Our findings suggest that exposure to PVP-I, of which concentrations are even lower than those used clinically, causes toxicity in epithelial cells. This knowledge would help us better understand the risk of the use of PVP-I against mucosa.

Subservient relationship of the peripheral second systolic pressure peak to the central hemodynamic parameters is preserved, irrespective of atherosclerosis progression in hypercholesterolemic rabbits

We investigated whether the subservient relationship of peripheral to central hemodynamic parameters, such as the augmentation index (AI) and the second systolic (SBP2) and pulse pressures, were preserved with the progression of atherosclerosis in the Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbit, an animal model for hypercholesterolemia and atherosclerosis. Male KHC rabbits, aged 12 and 24 months, were anesthetized with pentobarbital sodium. Two catheter-tip transducers were introduced to the central (ascending aorta) and peripheral (distal region of the right brachial artery) arteries through the left common carotid and the right radial arteries, respectively. Pressure waves were simultaneously recorded under regular atrial pacing to investigate changes in response to the intravenous infusion of angiotensin II (Ang II) (30-40 ng kg(-1) min(-1)) and sodium nitroprusside (NTP) (20-30 μg kg(-1) min(-1)). Central systolic blood pressure (cSBP) and diastolic blood pressure (DBP), peripheral systolic blood pressure (pSBP) and DBP, and peripheral second systolic blood pressure (pSBP2) showed no significant difference between the 12- and 24-month-old groups before the administration of vasoactive drugs. There was no significant difference in central AI (cAI) between the two age groups before the drug infusion, even though atherosclerosis progressed with aging. Peripheral AI (pAI) changed in parallel with cAI in response to vasopressor and depressor actions due to the infusion of Ang II and NTP, respectively. We conclude that the subservience of pSBP2 to cSBP and pAI to cAI, in addition to the regression relationship of these parameters between peripheral and central arteries, were well preserved, irrespective of the progression of atherosclerosis.

Does the augmentation index of pulse waves truly increase with progression of atherosclerosis? An experimental study with hypercholesterolemic rabbits

BACKGROUND

Recently, the central augmentation index (AIx) has been reported to show a nonlinear correlation with age. We investigated whether the AIx of the central artery changes with the progression of atherosclerosis in Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits.

METHODS

We simultaneously recorded pressure and flow waves in the ascending aorta in normal and KHC rabbits aged 10-12, 22-24, and 34-36 months, under pentobarbital anesthesia.

RESULTS

The systolic, diastolic, and mean arterial pressures and total peripheral vascular resistance were significantly higher in KHC rabbits than in their age-matched controls. The systolic pressure of the KHC rabbits increased with age. Additionally, the AIx of the KHC rabbits was significantly higher than that of their age-matched controls, although the AIx did not show a significant age-dependent increase in either of the two rabbit groups. However, the development of atherosclerotic lesions progressed markedly in KHC rabbits, and the early and late (pulse pressure [PP]) systolic waves increased progressively in amplitude with age in the KHC rabbits. On the other hand, no significant differences were seen in the normal and KHC rabbits' cardiac output (CO), stroke volume (SV), or heart rate (HR) at any age, nor did the two strains show significant age-related changes in these variables. Aortic compliance (SV/PP) was significantly lower in the 22-24- and 34-36-month-old KHC rabbits than in their age-matched controls, and decreased with age in the KHC rabbits.

CONCLUSIONS

Although the progression of atherosclerosis stiffened the aortic wall, it did not affect the AIx. This was partly the result of the decreased distensibility of the wall, in which the pressure waves used to determine AIx were measured.

Reducing radiation exposure using commonly available objects

OBJECTIVES

One and a half years have passed since the Fukushima Daiichi nuclear power plant disaster. The environmental radiation dose rate was not critical, but an existing exposure situation has been identified in a large part of Fukushima Prefecture. Although people continue to live and work in the contaminated area, they are not provided with sufficient information to reduce their exposure to radiation by themselves. In this study, we attempt to evaluate the efficiency of radiation shielding by using everyday items widely available to people.

METHODS

NaI scintillation and Geiger-Müller survey meters were used to measure the radiation dose of (1) contaminated soil and (2) soil covered with commonly available items.

RESULTS

In the soil at a depth of 10 cm from the surface, the radiation dose rate decreased from 3.36 to 0.65 μSv/h, and the count rate decreased from 3,120 to 352 cpm. Both the radiation dose rate and count rate reduced when the soil was covered with everyday items, such as a magazine more than 20 mm thick, a polystyrene foam board, and a wooden board of the same thickness.

CONCLUSIONS

To protect residents from unnecessary radiation exposure in the existing exposure situation, covering contaminated soil with a wooden board or a magazine, either of them 20 mm thick, is useful to reduce the radiation dose.

Long-term stabilization of respiratory conditions in patients with spinal muscular atrophy type 2 by continuous positive airway pressure: a report of two cases

Spinal muscular atrophy (SMA) type 2 is a motor neuron disease that leads to severe congenital muscle atrophy. The majority of adult patients are at risk of death due to respiratory failure. Here, we report on two patients with SMA type 2 who repeatedly developed bronchitis and pneumonia. The patient in Case 1 was a 48-year-old female lacking exon 7 of the survival motor neuron gene (SMN) 1. The patient in Case 2 was a 37-year-old female lacking exons 7 and 8 in SMN 1 and exon 5 in the neuronal apoptosis inhibitory protein (NAIP) gene. We applied continuous positive airway pressure (CPAP) in both cases because their data on polysomnography showed obstructive sleep apnea (OSA). CPAP treated their respiratory symptoms as well as those due to OSA. Moreover, CPAP stabilized the respiratory condition of Case 1 for seven years and seven months and that of Case 2 for five years and four months. These findings suggest that CPAP alone can achieve long-term improvement in the respiratory condition in patients with SMA type 2.

An assessment of radiation doses at an educational institution 57.8 km away from the Fukushima Daiichi nuclear power plant 1 month after the nuclear accident

OBJECTIVES

On 11 March 2011, the Great East Japan Earthquake occurred. Due to this earthquake and subsequent tsunami, malfunctions occurred at the Fukushima Daiichi nuclear power plant. Radioactive material even reached the investigated educational institution despite being 57.8 km away from the power station. With the goal of ensuring the safety of our students, we decided to carry out a risk assessment of the premises of this educational institution by measuring radiation doses at certain locations, making it possible to calculate estimated radiation accumulation.

METHODS

Systematic sampling was carried out at measurement points spaced at regular intervals for a total of 24 indoor and outdoor areas, with 137 measurements at heights of 1 cm and 100 cm above the ground surface. Radiation survey meters were used to measure environmental radiation doses.

RESULTS

Radiation dose rates and count rates were higher outdoors than indoors, and higher 1 cm above the ground surface than at 100 cm. Radiation doses 1 cm above the ground surface were higher on grass and moss than on asphalt and soil. The estimated radiation exposure for a student spending an average of 11 h on site at this educational institution was 9.80 μSv.

CONCLUSIONS

Environmental radiation doses at our educational institution 57.8 km away from the Fukushima Daiichi nuclear power plant 1 month after the accident were lower than the national regulation dose for schools (3.8 μSv/h) at most points. Differences in radiation doses depending on outdoor surface properties are important to note for risk reduction.

Plasma membrane aquaporin AqpZ protein is essential for glucose metabolism during photomixotrophic growth of Synechocystis sp. PCC 6803

The genome of Synechocystis PCC 6803 contains a single gene encoding an aquaporin, aqpZ. The AqpZ protein functioned as a water-permeable channel in the plasma membrane. However, the physiological importance of AqpZ in Synechocystis remains unclear. We found that growth in glucose-containing medium inhibited proper division of ΔaqpZ cells and led to cell death. Deletion of a gene encoding a glucose transporter in the ΔaqpZ background alleviated the glucose-mediated growth inhibition of the ΔaqpZ cells. The ΔaqpZ cells swelled more than the wild type after the addition of glucose, suggesting an increase in cytosolic osmolarity. This was accompanied by a down-regulation of the pentose phosphate pathway and concurrent glycogen accumulation. Metabolite profiling by GC/TOF-MS of wild-type and ΔaqpZ cells revealed a relative decrease of intermediates of the tricarboxylic acid cycle and certain amino acids in the mutant. The changed levels of metabolites may have been the cause for the observed decrease in growth rate of the ΔaqpZ cells along with decreased PSII activity at pH values ranging from 7.5 to 8.5. A mutant in sll1961, encoding a putative transcription factor, and a Δhik31 mutant, lacking a putative glucose-sensing kinase, both exhibited higher glucose sensitivity than the ΔaqpZ cells. Examination of protein expression indicated that sll1961 functioned as a positive regulator of aqpZ gene expression but not as the only regulator. Overall, the ΔaqpZ cells showed defects in macronutrient metabolism, pH homeostasis, and cell division under photomixotrophic conditions, consistent with an essential role of AqpZ in glucose metabolism.

Case reports of unexpected suicides in patients within six months after stroke

Suicide after stroke is a grievous occurrence. Since the majority of cases under study had shown signs of recovery from stroke, persons surrounding these patients were severely shocked by these suicides. Six patients who attempted suicide within six months after stroke were investigated to determine factors following stroke that relate to suicide in order to prevent future post-stroke suicides. Clinical findings in these six cases were retrospectively analyzed in collaboration with stroke neurologists and coworkers caring for these patients. Four of six patients had sustained a recent infarction extending from the temporal cortex to the parietal cortex. Four of six patients showed depression, and five of six patients showed moderate disability after stroke. Physicians should carefully observe patients with infarction extending from the temporal cortex to the parietal cortex, depression and moderate disability, in order to prevent suicidal behavior.

The effect of topical amiloride eye drops on tear quantity in rabbits

PURPOSE

To investigate the presence of epithelial sodium channels (ENaC) in rabbit and human conjunctival epithelium and to test the effects of topical amiloride, a potassium-sparing diuretic that blocks the ENaC, on tear quantity in rabbits.

METHODS

Both healthy normal human and rabbit conjunctival tissues underwent immunohistochemistry staining for ENaC-α and γ subunits as well as for reverse transcription-polymerase chain reaction (RT-PCR) for detection of ENaC-α and ENaC-γ subunit mRNA expression. Rabbits were instilled topical amiloride eye drops and tear function tests were performed before and after instillations.

RESULTS

Immunohistochemical staining for ENaC-α subunit in all rabbit eyes showed positive staining in apical and basal conjunctival epithelial cells. Human conjunctival epithelia revealed positive staining with ENaC-α antibody especially in the apical and basal layers. Immunohistochemistry staining with ENaC- γ antibody also revealed positive staining of the conjunctival epithelial cells especially in the basal layers. The ENaC-α mRNA was detected in samples from healthy white rabbit conjunctival epithelia, and ENaC-α and ENaC- γ mRNAs were detected in samples from healthy human conjunctival epithelia. The mean tear quantity showed a significant increase at 15 and 30 min compared to the pre-instillation value in eyes assigned to amiloride eye drops. The mean tear quantity at 15 and 30 min was significantly higher in the amiloride group compared to the control eyes.

CONCLUSIONS

Topical amiloride application appears to increase the quantity of preocular tears owing to inhibition of conjunctival epithelial sodium channels.

Potential of Heterotopic Fibroblasts as Autologous Transplanted Cells for Tracheal Epithelial Regeneration

The tracheal epithelium maintains the health of the respiratory tract through mucociliary clearance and regulation of ion and water balance. When the trachea is surgically removed, artificial grafts have been clinically used by our group to regenerate the trachea. In such cases, the tracheal epithelium needs 2 months for functional regeneration. Previous study has shown that fibroblasts facilitate tracheal epithelial regeneration. In this study, heterotopic fibroblasts originating from the dermis, nasal, and gingival mucosa were cocultured with tracheal epithelial cells to evaluate their potential as autologous transplanted cells for tracheal epithelial regeneration. The epithelia induced by the heterotopic fibroblasts showed differences in structure, cilia development, mucin secretion, and expression of ion and water channels. These results indicated that nasal fibroblasts could not induce mature tracheal epithelium and that dermal fibroblasts induced epidermis-like epithelium. Only the gingival fibroblasts (GFBs) could induce morphologically and functionally normalized tracheal epithelium comparable to the epithelium induced by tracheal fibroblasts. Epithelial cell proliferation and migration were also upregulated by GFBs. These results indicate that GFBs are useful as autologous transplant cells for tracheal epithelial regeneration.

Mild hypertension in young Kurosawa and Kusanagi-hypercholesterolaemic (KHC) rabbits

The coexistence of hypertension and hypercholesterolaemia from youth may increase the prevalence of and mortality from cardiovascular disease and stroke. We thus investigated haemodynamics of mild hypertension in young Kurosawa and Kusanagi-hypercholesterolaemic (KHC) rabbits aged 10-12 months old, as models of heritable hypercholesterolaemia. Pressure and flow waves were simultaneously recorded at the ascending aorta with a catheter-tip micromanometer and ultrasonic flow meter under pentobarbital anaesthesia, respectively. Systolic (119.3 +/- 6.5 and 138.4 +/- 7.4 mmHg (mean +/- SD) for control and KHC rabbit groups; p < 0.001), diastolic (95.7 +/- 6.1 and 109.8 +/- 5.2; p < 0.001), mean (105.8 +/- 6.5 and 122.5 +/- 4.9; p < 0.001) and pulse (23.7 +/- 2.5 and 28.6 +/- 4.0; p < 0.001) pressures as well as total peripheral vascular resistance (0.32 +/- 0.02 and 0.37 +/- 0.03 mmHg/ml/min; p < 0.001) were significantly greater in the KHC rabbit group than those in the age-matched control rabbit group, respectively, while there were no significant differences in the mean aortic flow, heart rate or stroke volume between the two rabbit groups. Aortic input impedance (p < 0.05) and reflection coefficient (p < 0.05) were significantly greater at lower frequency in the KHC rabbit group than in the control rabbit group, whereas there was no significant difference in the characteristic impedance between the two rabbit groups. Plasma angiotensin I (p < 0.01) and II (p < 0.01) levels and serum angiotensin converting enzyme activity (p < 0.05) were significantly greater in the KHC rabbit group than in the age-matched control rabbit group. Atheromatous plaque was in the early stage and composed mainly of abundant foam cells. Neither sclerotic lesions nor stenosis were observed in main peripheral arteries. The mild hypertension in young KHC rabbits was due partly to the increased activity of the renin-angiotensin system. These findings may be thought provoking in elucidating the mechanism and developing preventive and therapeutic strategies in young patients with coexistent hypertension and hypercholesterolaemia.

Molecular cloning and characterization of mouse aquaporin 6

In the rat kidney, aquaporin (AQP) 6 is localized in the intracellular vesicle membranes of type-A intercalated cells of the collecting duct; mouse AQP6 (mAQP6) has not been characterized. Although mAQP6 was originally cloned from cDNA in a mouse cerebellum library (GenBank NM 175087), we have independently cloned a cDNA encoding mAQP6 from an adult kidney cDNA library (C57BL/6J strain). We identified two different spliced variants of mAQP6: mAQP6a and mAQP6b. The mAQP6a isoform is almost identical to that of rat AQP6, whereas mAQP6b is identical to that reported in the mouse cerebellum library mentioned above. We found that the mRNA expression of these two spliced variants is regulated in a tissue-specific and age-dependent manner. Functional analyses of water and ion permeation revealed that mAQP6a functions like rat AQP6 and that mAQP6b does not function as either a water channel or an ion channel under our experimental conditions.

Effect of Fibroblasts on Tracheal Epithelial Regenerationin vitro

Several artificial grafts for covering deficient trachea have been produced through tissue engineering. Recently, our group clinically used an artificial trachea made from collagen sponge for patients with noncircumferential tracheal resection. However, the slowness of epithelial regeneration on the surface of the artificial trachea was confirmed as one particular problem. In this study, we co-cultured tracheal epithelial cells with fibroblasts and examined effects of fibroblasts on epithelial regeneration in vitro. Fibroblasts activated epithelial cell proliferation and migration. In co-culture with fibroblasts, epithelial cells reconstructed pseudostratified epithelium, which was composed of ciliated, goblet, and basal cells. Furthermore, a basement membrane was reconstructed between epithelial cells and fibroblasts, and integrin beta4 was also observed there. Fibroblasts rapidly increased mucin secretion by epithelial cells. These results indicate that stimulatory effects of fibroblasts on epithelial cell migration, proliferation, and differentiation would reduce the time required for covering of epithelial cells on the defect of luminal surface and hasten regeneration of morphologically and functionally normalized epithelium involving the reconstruction of basement membrane.

Conversion of aquaporin 6 from an anion channel to a water-selective channel by a single amino acid substitution

Aquaporin (AQP) 6 belongs to the aquaporin water channel family. Unlike other aquaporins, AQP6 functions not as a water channel but as an anion-selective channel. Single-channel analyses have shown AQP6 to flicker rapidly between closed and open status. The atomic structure of AQP1 and amino acid sequence alignments of the mammalian aquaporins reveal two well conserved glycine residues: Gly-57 in transmembrane helix (TM) 2 and Gly-173 in TM5 reside at the contact point where the two helices cross in human AQP1. Uniquely, all known mammalian orthologs of AQP6 have an asparagine residue (Asn-60) at the position corresponding to Gly-57. Here we show that a single residue substitution (N60G in rat AQP6) totally eliminates the anion permeability of AQP6 when expressed in Xenopus oocytes, but the N60G oocytes exhibit significantly higher osmotic water permeability under basal conditions. Replacement of the glycine at this site in AQP0, AQP1, and AQP2 blocked expression of the mutants at the oocyte plasma membrane. We propose that the asparagine residue at the contact point between TM2 and TM5 in AQP6 may function as a teeter board needed for rapid structural oscillations during anion permeation.

Detecting ATP release by a biosensor method

Cells release adenosine 5'-triphosphate (ATP) into the extracellular space in response to various stimuli. This released ATP plays an important physiological role in cell-to-cell signal transduction. The bulk ATP concentration can be detected using a conventional luciferin-luciferase assay. However, the ATP concentration in the vicinity of the cell surface is often different from the bulk concentration because of its rapid degradation by ecto-ATPases and because of delayed diffusion due to unstirred layer effects. Here, we describe a simple biosensor method to measure the local ATP concentration on the cell surface in real time. The method is based on the ATP-dependent opening of ligand-gated cation channels of purinergic P2X receptors expressed in undifferentiated pheochromocytoma (PC12) cells or in human embryonic kidney 293 (HEK293) cells stably transfected with recombinant P2X2 purinergic receptors. Under the whole-cell configuration of patch-clamp, a sensor PC12 cell or HEK293 is positioned within the proximity of a target cell, and the P2X-mediated currents induced by ATP released from a given site on the target cell surface is measured. The ATP release is quantified by a calibration procedure utilizing local puff applications of ATP at preset concentrations.

Effects of microgravity on organ development of the neonatal rat

We analyzed various organs in the same rats to study effects of gravitational condition on organ development of the neonatal rat in this study. Eight-day old and 14-day old Sprague-Dawley rats were flown for 16 days on the Space Shuttle Columbia (April 17-May 3, 1998). The organs were weighed and the ratio of the organ weight to the body weight (organ weight ratio; OBR) was calculated. Tissues were analyzed using anatomical, immunohistochemical and molecular biological technique. Six animals of the 8-day old group were reared on the ground for 30 more days after landing. The differences between flight and control rats in 8-day group were drastic. The lung, heart, kidney and adrenal glands in flight rats were significantly larger than that of control rats in OBR comparison. However, only the lung and kidney were still larger after 30 more days on ground. The kidney in flight rats performed pelvis expansion with down-regulation of aquaporin-2 expression confirmed by immunohistochemistry. The thymus, spleen, mesentery and pancreas were smaller in OBR. But the thymus in flight rats was heavier after 30 more days. The organs in flight rats which had no differences in OBR showed normal characteristics in histological analysis. We also found that the number of unmyelinated fibers of the aortic nerve in flight rats of 8-day group was smaller than that in control rats. In flight rats of the 14-day group, only the kidney was heavier and the ovary was lighter as compared to the controls. These results implied the second week of life was important for development during spaceflight. And the sensitivity and the critical period on neonatal development under microgravity might differ in each organ.

Addition of a peptide tag at the C terminus of AtHKT1 inhibits its Na+ transport

Eight transmembrane segments in the Arabidopsis Na+ transporter, AtHKT1, have been proposed to be arranged around the axis of the pore. We report here that the addition of a GFP or a FLAG tag to the C terminus of AtHKT1 impairs the Na+ transport in Xenopus ooytes as detected by electrophysiological measurements.

Change in the static rheological properties of the aorta in Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits with progress of atherosclerosis

The rheological properties of the arterial wall have intimate connections with the fine structure of the wall. Alteration in fine structure due to cardiovascular disease, such as atherosclerosis, could affect the rheological characteristics of the wall. The present study was designed to investigate changes in the static rheological properties of the aorta in Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits aged 10-12, 22-24 and 34-36 months in relation to histological alteration of the wall due to progression of atherosclerosis with age. Circumferential wall strips were excised from the ascending, proximal descending thoracic and proximal abdominal aortas and their stress/strain relationship was recorded. Tensile force of the wall showed a slight but insignificant decrease in the KHC rabbit group aged 10-12 months compared to that in the age-matched control group in the proximal thoracic aorta and increased significantly with ageing in the KHC rabbits in these aortic regions mainly at medium and high strain ranges. Wall stress was significantly smaller in the 10-12 months old KHC rabbit group than in the age-matched control group in the proximal thoracic and proximal abdominal aortas and increased significantly with ageing in the KHC rabbit groups chiefly at medium and high strain ranges. Incremental elastic modulus determined at 50% stretching of the initial length of the wall strip was also significantly lower in the KHC rabbit group aged 10-12 months in comparison to that in the age-matched control group and increased significantly with ageing in the KHC rabbit group. The intima thickened severely with abundant foam cells in the KHC rabbits aged 10-12 months. With increasing age, collagen and elastin fibres showed signs of gradual proliferation among the foam cells. The aortic wall in KHC rabbits was viscoelastic in the relatively early stage of atherosclerosis due to abundant foam cells, and thereafter increased in stiffness gradually with fibrous proliferation and calcification. We can conclude that the static rheological properties of the atherosclerotic aortic wall changed in association with alteration in the microstructure of the wall with progression of atherosclerosis.

Characteristic change in local pulse wave velocity in different segments of the atherosclerotic aorta in KHC rabbits

BACKGROUND

Pulse wave velocity, conventionally determined between the carotid and femoral arteries, is a useful measure to estimate stiffness of the aorta. We investigated local pulse wave velocity (LPWV) in different segments in the aorta with relatively early-stage atherosclerosis in relation to the extent and severity of atherosclerotic lesions.

METHODS

Pressure waves were recorded in eight aortic positions using two catheters with one or two micromanometers to determine LPWV in the ascending aorta, distal end of the aortic arch, proximal, middle, and distal thoracic aortas, and proximal, middle, and distal abdominal aortas in Kurosawa and Kusanagi-hypercholesterolemic (KHC) and normal rabbits aged 10 to 12 months.

RESULTS

The LPWV in the KHC rabbit was greatest in the aortic arch, decreased almost to the normal level in the middle and distal thoracic aorta, increased in the proximal abdominal aorta, and showed almost identical change to that in the normal rabbit in the middle and distal abdominal aortic regions. There was significant difference in LPWV in the aortic arch, proximal thoracic, and proximal abdominal aortas between the two rabbit groups. The sclerotic lesion was prominent in the aortic arch, proximal thoracic aorta, and proximal abdominal aortas. The wall was severely thickened with abundant foam cells. The significant increase in LPWV would be mainly related to the increased wall thickness in these aortic regions.

CONCLUSIONS

We can conclude that LPWV reflects well the distribution and severity of atherosclerotic lesion and the increased wall thickness in the local aortic region in which pulse waves were traveled.

Morphological characteristics of the kidney and lung in the neonatal rats observed after 16 days spaceflight

The aim of this study is to examine the structural development in kidney and lung macroscopically which relate with cardiovascular system in rats raised in space. Twenty three nine-day old rats and six fifteen-day old rats, which were launched at these ages and nursed by their dams in the Space Shuttle Colombia for 16 days (STS-90; Neurolab). Seventeen animals of the nine-day old rats were defined as the nine-day group, and the rest was defined as the re-adaptation group, which were reared on the ground for 30 more days after landing. The organs were weighed and the ratio of the organ weight to the body weight (body weight ratio) was calculated. Both of lung and kidney in flight rats were significantly heavier than ground controls in the body weight ratio. We found that the kidney in the nine-day and the fifteen-day group tended to extend of dorsal-ventral length in macroscopic observations. However, this difference was not observed in the re-adaptation group. These results suggest that space environment may affect in kidney development. On the other hand, the lung had no differences in macroscopic structure among flight and control groups.

The mitochondrial acetoacetyl-CoA thiolase (T2) deficiency in Japanese patients: urinary organic acid and blood acylcarnitine profiles under stable conditions have subtle abnormalities in T2-deficient patients with some residual T2 activity

Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inborn error of metabolism affecting isoleucine and ketone bodies in the catabolic process. Mutation analysis and expression analysis of mutant cDNAs have facilitated the division of T2-deficient patients into two groups: those with null mutations in either allele (group 1) and those with mutation(s) retaining some residual T2 activity in at least one of two mutant alleles (group II). Among 5 Japanese T2-deficient patients, GK01 belonged to group I and the other patients (GK19, GK19B, GK30 and GK31) to group II. As we have suggested previously, the severity of ketoacidotic episodes in the group II patients was similar to that in the group I patient. However, the urinary organic acid and blood spot acylcarnitine profiles under stable conditions differed between the two groups. The group I patient had typical profiles for the T2 deficiency. In contrast, in all four patients in group II, tiglylglycine was not or was only faintly detected and the 2-methyl-3-hydroxybutyrate levels were less than the cutoff value. Their tiglylcarnitine levels were within the normal range and 2-methyl-3-hydroxy-, butyrylcarnitine was detected just around the cutoff value in our newborn screening pilot test. Hence, these analyses under stable conditions are not reliable for diagnosing the T2 deficiency in the group II patients. The T2 deficiency (group II) can be misdiagnosed as normal if these analyses are performed under nonepisodic conditions and possibly during the newborn screening for inborn errors of metabolism.