HLA-DPB1 mismatch induces a graft-versus-leukemia effect without severe acute GVHD after single-unit umbilical cord blood transplantation.

Although it is known that human leukocyte antigen (HLA)-DPB1 disparity has a strong impact on outcomes in unrelated hematopoietic transplantation with induction of acute graft-versus-host disease (GVHD) and a graft-versus-leukemia (GVL) effect, its role in unrelated umbilical cord blood transplantation (UR-CBT) has yet to be fully clarified. Our current study is being conducted to elucidate the impact of HLA-DPB1 mismatch, along with the effect of other HLA loci mismatches at the allele level. HLA six loci alleles were retrospectively typed in 1157 Japanese donors and patients with leukemia or myelodysplastic syndrome who underwent transplantation with a single unit of cord blood. HLA-DPB1 mismatch was associated with a significant reduction in leukemia relapse (hazard ratio 0.61, P<0.001), whereas the other HLA loci allele-level mismatches did not. No significant effect of HLA-DPB1 mismatch was observed in the risk of acute GVHD, engraftment or mortality. This HLA-DPB1 GVL effect without induction of severe acute GVHD or deterioration of survival rate has not been reported in unrelated bone marrow or peripheral blood stem cell transplantations, suggesting apparent advantages of UR-CBT. Accordingly, selection of an HLA-DPB1 mismatch cord blood might be the preferable choice for single-unit UR-CBT.

Therapy-related acute myeloid leukemia and myelodysplastic syndrome after hematopoietic cell transplantation for lymphoma.

Therapy-related acute myeloid leukemia and myelodysplastic syndrome (t-AML/MDS) represent severe late effects in patients receiving hematopoietic cell transplantation (HCT) for lymphoma. The choice between high-dose therapy with autologous HCT and allogeneic HCT with reduced-intensity conditioning remains controversial in patients with relapsed lymphoma. We retrospectively analyzed incidence and risk factors for the development of t-AML/MDS in lymphoma patients treated with autologous or allogeneic HCT. A total of 13 810 lymphoma patients who received autologous (n=9963) or allogeneic (n=3847) HCT between 1985 and 2012 were considered. At a median overall survival (OS) of 52 and 46 months in autologous and allogeneic HCT groups, respectively, lymphoma patients receiving autologous HCT (1.38% at 3 years after autologous HCT) had a significant risk for developing t-AML/MDS compared to allogeneic HCT (0.37% at 3 years after allogeneic HCT, P<0.001). Significant risk factors for the development of t-AML/MDS after autologous and allogeneic HCT were high-stage risk at HCT (P=0.04) or secondary malignancies (P<0.001) and receiving cord blood stem cell (P=0.03) or involved field radiotherapy (P=0.002), respectively. Strategies that carefully select lymphoma patients for autologous HCT, by excluding lymphoma patients with high-stage risk at HCT, may allow the identification of individual lymphoma patients at particular high risk for t-AML/MDS.

Impact of HLA allele mismatch on the clinical outcome in serologically matched related hematopoietic SCT.

In unrelated hematopoietic SCT (HSCT), HLA allele mismatch has been shown to have a significant role. To clarify the importance of HLA allele mismatch in the GVH direction in related HSCT, we retrospectively evaluated 2377 patients who received stem cells from an HLA serologically matched related donor in the GVH direction using the database of the Japan Society for Hematopoietic Cell Transplantation. The cumulative incidences of grade II-IV and grade III-IV acute GVHD in patients with an HLA allele-mismatched donor (n=133, 5.6%) were significantly higher than those in patients with an HLA allele-matched donor. Multivariate analyses showed that the presence of HLA allele mismatch was associated with increased risks of grade II-IV and grade III-IV acute GVHD. In particular, HLA-B mismatch and multiple allele mismatches were associated with an increased risk of acute GVHD. The presence of HLA allele mismatch was associated with an inferior OS owing to an increased risk of non-relapse mortality (NRM). In conclusion, the presence of HLA allele mismatch in the GVH direction in related HSCT was associated with increased risks of GVHD and NRM, which led to an inferior OS. HLA allele typing is recommended in related HSCT.

Identification of the MICA*070 allele by sequencing and phasing.

A novel MICA allele, MICA*070, was defined by sequencing. The new allele differs from the MICA*008:04 sequence in exon 2, encoding a C instead of G corresponding to cDNA nucleotide position 183. This nucleotide substitution is predicted to encode serine instead of arginine at residue 38 of the α1 domain of the MICA molecule.

Expression of distinct alpha 1-adrenoceptor phenotypes in the iris of pigmented and albino rabbits.

BACKGROUND AND PURPOSE: The expression of multiple pharmacological phenotypes including alpha(1L)-adrenoceptor has recently been reported for alpha(1)-adrenoceptors. The purpose of the present study was to identify alpha(1)-adrenoceptor phenotypes in the irises of pigmented and albino rabbits. EXPERIMENTAL APPROACH: Radioligand binding and functional bioassay experiments were performed in segments or strips of iris of pigmented and albino rabbits, and their pharmacological profiles were compared. KEY RESULTS: [(3)H]-silodosin at subnanomolar concentrations bound to intact segments of iris of pigmented and albino rabbits at similar densities (approximately 240 fmol x mg(-1) protein). The binding sites in the iris of a pigmented rabbit were composed of a single component showing extremely low affinities for prazosin, hydrochloride [N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethamine hydrochloride (RS-17053)] and 5-methylurapidil, while two components with high and low affinities for prazosin, RS-17053 and 5-methylurapidil were identified in irises from albino rabbits. In contrast, specific binding sites for [(3)H]-prazosin were not clearly detected because a high proportion of non-specific binding and/or low affinity for prazosin occurred. Contractile responses of iris dilator muscle to noradrenaline were antagonized by the above ligands, and their antagonist affinities were consistent with the binding estimates at low-affinity sites identified in both strains of rabbits. CONCLUSIONS AND IMPLICATIONS: A typical alpha(1L) phenotype with extremely low affinity for prazosin is exclusively expressed in the iris of pigmented rabbits, while two distinct phenotypes (alpha(1A) and alpha(1L)) with high and moderate affinities for prazosin are co-expressed in the iris of albino rabbits. This suggests that a significant difference in the expression of phenotypes of the alpha(1)-adrenoceptor occurs in the irises between the two strains of rabbits.

Identification of alpha 1L-adrenoceptor in mice and its abolition by alpha 1A-adrenoceptor gene knockout.

BACKGROUND AND PURPOSE: The alpha(1L)-adrenoceptor has pharmacological properties that distinguish it from three classical alpha(1)-adrenoceptors (alpha(1A), alpha(1B) and alpha(1D)). The purpose of this was to identify alpha(1L)-adrenoceptors in mice and to examine their relationship to classical alpha(1)-adrenoceptors. EXPERIMENTAL APPROACH: Radioligand binding and functional bioassay experiments were performed on the cerebral cortex, vas deferens and prostate of wild-type (WT) and alpha(1A)-, alpha(1B)- and alpha(1D)-adrenoceptor gene knockout (AKO, BKO and DKO) mice. KEY RESULTS: The radioligand [(3)H]-silodosin bound to intact segments of the cerebral cortex, vas deferens and prostate of WT, BKO and DKO but not of AKO mice. The binding sites were composed of two components with high and low affinities for prazosin or RS-17053, indicating the pharmacological profiles of alpha(1A)-adrenoceptors and alpha(1L)-adrenoceptors. In membrane preparations of WT mouse cortex, however, [(3)H]-silodosin bound to a single population of prazosin high-affinity sites, suggesting the presence of alpha(1A)-adrenoceptors alone. In contrast, [(3)H]-prazosin bound to two components having alpha(1A)-adrenoceptor and alpha(1B)-adrenoceptor profiles in intact segments of WT and DKO mouse cortices, but AKO mice lacked alpha(1A)-adrenoceptor profiles and BKO mice lacked alpha(1B)-adrenoceptor profiles. Noradrenaline produced contractions through alpha(1L)-adrenoceptors with low affinity for prazosin in the vas deferens and prostate of WT, BKO and DKO mice. However, the contractions were abolished or markedly attenuated in AKO mice. CONCLUSIONS AND IMPLICATIONS: alpha(1L)-Adrenoceptors were identified as binding and functional entities in WT, BKO and DKO mice but not in AKO mice, suggesting that the alpha(1L)-adrenoceptor is one phenotype derived from the alpha(1A)-adrenoceptor gene.

Native profiles of alpha(1A)-adrenoceptor phenotypes in rabbit prostate.

BACKGROUND AND PURPOSE: alpha(1)-Adrenoceptors in the rabbit prostate have been studied because of their controversial pharmacological profiles in functional and radioligand binding studies. The purpose of the present study is to determine the native profiles of alpha(1)-adrenoceptor phenotypes and to clarify their relationship. EXPERIMENTAL APPROACH: Binding experiments with [3H]-silodosin and [3H]-prazosin were performed using intact tissue segments and crude membrane preparations of rabbit prostate and the results were compared with alpha(1)-adrenoceptor-mediated prostate contraction. KEY RESULTS: [3H]-Silodosin at subnanomolar concentrations bound specifically to intact tissue segments of rabbit prostate. However, [3H]-prazosin at the same range of concentrations failed to bind to alpha(1)-adrenoceptors of intact segments. Binding sites of [3H]-silodosin in intact segments were composed of alpha(1L) phenotype with low affinities for prazosin (pKi=7.1), 5-methyurapidil and N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethamine hydrochloride (RS-17053), and alpha(1A)-like phenotype with moderate affinity for prazosin (pKi=8.8) but high affinity for 5-methyurapidil and RS-17053. In contrast, both radioligands bound to a single population of alpha(1)-adrenoceptors in the membrane preparations at the same density with a subnanomolar affinity, showing a typical profile of 'classical' alpha(1A)-adrenoceptors (pKi for prazosin=9.8). The pharmacological profile of alpha(1)-adrenoceptor-mediated prostate contraction was in accord with the alpha(1L) phenotype observed by intact segment binding approach. CONCLUSIONS AND IMPLICATIONS: Three distinct phenotypes (alpha(1L) and alpha(1A)-like phenotypes in the intact segments and a classical alpha(1A) phenotype in the membranes) with different affinities for prazosin were detected in rabbit prostate. It appears that the three phenotypes are phenotypic subtypes of alpha(1A)-adrenoceptors, but are not genetically different subtypes.

Identification of the alpha1L-adrenoceptor in rat cerebral cortex and possible relationship between alpha1L- and alpha1A-adrenoceptors.

BACKGROUND AND PURPOSE: In addition to alpha1A, alpha1B and alpha1D-adrenoceptors (ARs), putative alpha1L-ARs with a low affinity for prazosin have been proposed. The purpose of the present study was to identify the alpha1A-AR and clarify its pharmacological profile using a radioligand binding assay. EXPERIMENTAL APPROACH: Binding experiments with [3H]-silodosin and [3H]-prazosin were performed in intact tissue segments and crude membrane preparations of rat cerebral cortex. Intact tissue binding assays were also conducted in rat tail artery. KEY RESULTS: [3H]-silodosin at subnanomolar concentrations specifically bound to intact tissue segments and membrane preparations of rat cerebral cortex at the same density (approximately 150 fmol mg(-1) total tissue protein). The binding sites in intact segments consisted of alpha1A and alpha1L-ARs that had different affinities for prazosin, while the binding sites in membranes showed an alpha1A-AR-like profile having single high affinity for prazosin. [3H]-prazosin also bound at subnanomolar concentrations to alpha1A and alpha1B-ARs but not alpha1L-ARs in cerebral cortex; the binding densities being approximately 200 and 290 fmol mg(-1) protein in the segments and the membranes, respectively. In the segments of tail artery, [3H]-silodosin only recognized alpha1A-ARs, whereas [3H]-prazosin bound to alpha1A and alpha1B-ARs. CONCLUSIONS AND IMPLICATIONS: The present study clearly reveals the presence of alpha1L-ARs as a pharmacologically distinct entity from alpha1A and alpha1B-ARs in intact tissue segments of rat cerebral cortex but not tail artery. However, the alpha1L-ARs disappeared after tissue homogenization, suggesting their decomposition and/or their pharmacological profile changes to that of alpha1A-ARs.

Electrogene therapy using endostatin, with or without suicide gene therapy, suppresses murine mammary tumor growth and metastasis.

Syngeneic inoculated metastatic mammary cancers received direct intratumoral injection of a plasmid vector containing either endostatin (pEndo) with or without a suicide gene (pHSVtk), pHSVtk alone or control vector once a week for 8 weeks. We applied electrogene transfer to the tumors after each injection and administered ganciclovir (GCV) to pHSVtk-transfected mice using an osmotic minipump. Anticancer efficacy was monitored using a variety of parameters, namely tumor volume, intratumoral microvessel density and DNA synthesis, number of mice with metastasis, and number of sites of metastasis per mouse. Tumor volume was significantly lower in all therapeutic groups, with the most effective growth suppression in the pEndo+pHSVtk/GCV group. Lymph node metastasis was significantly less frequent in all therapeutic groups, whereas the multiplicity of lung metastases was significantly lower only in the pEndo and pEndo+pHSVtk/GCV groups. All therapeutic groups showed significantly lower intratumor microvessel density and DNA synthesis. The pEndo and pEndo+pHSVtk/GCV groups also showed a significant reduction in the numbers of dilated lymphatic vessels containing intralumenal tumor cells. Our data suggest that endostatin electrogene therapy alone or in combination with pHSVtk/GCV suicide gene therapy is more beneficial than suicide gene therapy alone. The observed antimetastatic activity of endostatin may be of high clinical significance in the treatment of metastatic breast cancer.

Comparison between reduced intensity and conventional myeloablative allogeneic stem-cell transplantation in patients with hematologic malignancies aged between 50 and 59 years.

To evaluate the efficacy of reduced-intensity stem-cell transplantation (RIST), we retrospectively compared outcomes of 207 consecutive Japanese patients aged between 50 and 59 years with hematologic malignancies who received RIST (n=70) and conventional stem-cell transplantation (CST) (n=137). CST recipients received total body irradiation (TBI)-based or busulfan/cyclophosphamide-based regimens. RIST regimens were purine analog-based (n=67), 2 Gy TBI-based (n=2), and others (n=1). Most CST recipients (129/137) received calcineurin inhibitors and methotrexate as graft-versus-host (GVHD) prophylaxis, while 32 RIST recipients received cyclosporin. In all, 23 CST and five RIST recipients died without disease progression within 100 days of transplant. Grade II to IV acute GVHD occurred in 56 CST and 38 RIST recipients. There was no significant difference in overall survival (OS) and progression-free survival between CST and RIST. On multivariate analysis on OS, five variables were significant: preparative regimens (CST vs RIST) (hazard ratio=1.92, 95% confidence interval, 1.25-2.97; P=0.003), performance status (2-4 vs 0-1) (2.50, 1.51-4.16; P<0.001), risk of underlying diseases (1.85, 1.21-2.83; P=0.004), acute GVHD (2.57, 1.72-3.84; P<0.001), and CML (0.38, 0.21-0.69; P=0.002). We should be careful in interpreting results of this small-sized retrospective study; however, reduced regimen-related toxicity might contribute to better survival in RIST. The low relapse rates following RIST suggest a strong antitumor activity through allogeneic immunity.

Roles of aquaporin-3 water channels in volume-regulatory water flow in a human epithelial cell line.

Membrane water transport is an essential event not only in the osmotic cell volume change but also in the subsequent cell volume regulation. Here we investigated the route of water transport involved in the regulatory volume decrease (RVD) that occurs after osmotic swelling in human epithelial Intestine 407 cells. The diffusion water permeability coefficient (Pd) measured by NMR under isotonic conditions was much smaller than the osmotic water permeability coefficient (Pf) measured under an osmotic gradient. Temperature dependence of Pf showed the Arrhenius activation energy (Ea) of a low value (1.6 kcal/mol). These results indicate an involvement of a facilitated diffusion mechanism in osmotic water transport. A mercurial water channel blocker (HgCl(2)) diminished the Pf value. A non-mercurial sulfhydryl reagent (MMTS) was also effective. These blockers of water channels suppressed the RVD. RT-PCR and immunocytochemistry demonstrated predominant expression of AQP3 water channel in this cell line. Downregulation of AQP3 expression induced by treatment with antisense oligodeoxynucleotides was found to suppress the RVD response. Thus, it is concluded that AQP3 water channels serve as an essential pathway for volume-regulatory water transport in, human epithelial cells.

Apoptotic and necrotic blebs in epithelial cells display similar neck diameters but different kinase dependency.

Apoptotic and necrotic blebs elicited by H(2)O(2) were compared in terms of dynamics, structure and underlying biochemistry in HeLa cells and Clone 9 cells. Apoptotic blebs appeared in a few minutes and required micromolar peroxide concentrations. Necrotic blebs appeared much later, prior to cell permeabilization, and required millimolar peroxide concentrations. Strikingly, necrotic blebs grew at a constant rate, which was unaffected throughout successive cycles of budding and detachment. At 1 microm diameter, the necks of necrotic and apoptotic blebs were almost identical. ATP depletion was discarded as a major factor for both types of bleb. Inhibition of ROCK-I, MLCK and p38MAPK strongly decreased apoptotic blebbing but had no effect on necrotic blebbing. Taken together, these data suggest the existence of a novel structure of fixed dimensions at the neck of both types of plasma membrane blebs in epithelial cells. However, necrotic blebs can be distinguished from apoptotic blebs in their susceptibility to actomyosin kinase inhibition.

Expression and role of mannose receptor/terminal high-mannose type oligosaccharide on osteoclast precursors during osteoclast formation.

Osteoclasts are formed from hematopoietic precursors via cell-cell fusion. We have previously reported that mannose residues are expressed on the outer membranes of monocytes during osteoclast differentiation. In the present study, we have attempted to demonstrate the pattern of expression levels of terminal high-mannose type oligosaccharide and to show that the mannose receptor is expressed on osteoclast precursor cells. Osteoclasts were formed using three different systems, namely mouse bone marrow cell culture, co-culture of mouse spleen cells with stromal cells, and RAW264.7 cell cultures. During osteoclast differentiation, the expression of terminal high-mannose type oligosaccharide gradually increased and then peaked at the stage of fusion in all three systems. Expression of the mannose receptor gradually increased during osteoclast differentiation in bone marrow cells and the co-culture system. In contrast, that in RAW264.7 cells had already been detected in the absence of the soluble receptor activator of NF-kappaB ligand and did not change during osteoclast differentiation. To ascertain whether expression of high-mannose type oligosaccharide is involved in tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cell (MNC) formation, glycosidase inhibitors were used on RAW264.7 cell culture. Castanospermine, an inhibitor of glucosidase I, inhibited the TRAP-positive MNCs, and deoxymannojirimycin, an inhibitor of alpha-mannosidase I, increased the TRAP-positive MNC formation. These results indicate that the binding of terminal high-mannose and mannose receptor is important for the process of cellular fusion in osteoclast formation.

Phloretin differentially inhibits volume-sensitive and cyclic AMP-activated, but not Ca-activated, Cl(-) channels.

Some phenol derivatives are known to block volume-sensitive Cl(-) channels. However, effects on the channel of the bisphenol phloretin, which is a known blocker of glucose uniport and anion antiport, have not been examined. In the present study, we investigated the effects of phloretin on volume-sensitive Cl(-) channels in comparison with cyclic AMP-activated CFTR Cl(-) channels and Ca(2+)-activated Cl(-) channels using the whole-cell patch-clamp technique. Extracellular application of phloretin (over 10 microM) voltage-independently, and in a concentration-dependent manner (IC(50) approximately 30 microM), inhibited the Cl(-) current activated by a hypotonic challenge in human epithelial T84, Intestine 407 cells and mouse mammary C127/CFTR cells. In contrast, at 30 microM phloretin failed to inhibit cyclic AMP-activated Cl(-) currents in T84 and C127/CFTR cells. Higher concentrations (over 100 microM) of phloretin, however, partially inhibited the CFTR Cl(-) currents in a voltage-dependent manner. At 30 and 300 microM, phloretin showed no inhibitory effect on Ca(2+)-dependent Cl(-) currents induced by ionomycin in T84 cells. It is concluded that phloretin preferentially blocks volume-sensitive Cl(-) channels at low concentrations (below 100 microM) and also inhibits cyclic AMP-activated Cl(-) channels at higher concentrations, whereas phloretin does not inhibit Ca(2+)-activated Cl(-) channels in epithelial cells.

Receptor-mediated control of regulatory volume decrease (RVD) and apoptotic volume decrease (AVD).

A fundamental property of animal cells is the ability to regulate their own cell volume. Even under hypotonic stress imposed by either decreased extracellular or increased intracellular osmolarity, the cells can re-adjust their volume after transient osmotic swelling by a mechanism known as regulatory volume decrease (RVD). In most cell types, RVD is accomplished mainly by KCl efflux induced by parallel activation of K+ and Cl- channels. We have studied the molecular mechanism of RVD in a human epithelial cell line (Intestine 407). Osmotic swelling results in a significant increase in the cytosolic Ca2+ concentration and thereby activates intermediate-conductance Ca2+-dependent K+ (IK) channels. Osmotic swelling also induces ATP release from the cells to the extracellular compartment. Released ATP stimulates purinergic ATP (P2Y2) receptors, thereby inducing phospholipase C-mediated Ca2+ mobilization. Thus, RVD is facilitated by stimulation of P2Y2 receptors due to augmentation of IK channels. In contrast, stimulation of another G protein-coupled Ca2+-sensing receptor (CaR) enhances the activity of volume-sensitive outwardly rectifying Cl- channels, thereby facilitating RVD. Therefore, it is possible that Ca2+ efflux stimulated by swelling-induced and P2Y2 receptor-mediated intracellular Ca2+ mobilization activates the CaR, thereby secondarily upregulating the volume-regulatory Cl- conductance. On the other hand, the initial process towards apoptotic cell death is coupled to normotonic cell shrinkage, called apoptotic volume decrease (AVD). Stimulation of death receptors, such as TNF receptor and Fas, induces AVD and thereafter biochemical apoptotic events in human lymphoid (U937), human epithelial (HeLa), mouse neuroblastoma x rat glioma hybrid (NG108-15) and rat phaeochromocytoma (PC12) cells. In those cells exhibiting AVD, facilitation of RVD is always observed. Both AVD induction and RVD facilitation as well as succeeding apoptotic events can be abolished by prior treatment with a blocker of volume-regulatory K+ or Cl- channels, suggesting that AVD is caused by normotonic activation of ion channels that are normally involved in RVD under hypotonic conditions. Therefore, it is likely that G protein-coupled receptors involved in RVD regulation and death receptors triggering AVD may share common downstream signals which should give us key clues to the detailed mechanisms of volume regulation and survival of animal cells. In this Topical Review, we look at the physiological ionic mechanisms of cell volume regulation and cell death-associated volume changes from the facet of receptor-mediated cellular processes.

Changes in bite force and occlusal contact area after orthognathic surgery for correction of mandibular prognathism.

OBJECTIVE: This study examined the long-term changes of bite force and occlusal contact area in patients with prognathous after orthognathic surgery with a newly developed pressure-sensitive sheet (Dental-Prescale; Fuji Photo Film Co). STUDY DESIGN: Fifty-seven patients with prognathous were examined. Bite force and occlusal contact area were measured just before operation and at 2 weeks, 1 month, 3 months, 6 months, 1 year, 2 years, and 3 years after operation. Forty control subjects with normal occlusion were also measured. RESULTS: The bite force and occlusal contact area of the patients were significantly greater than the preoperative level at 1 year, 2 years, and 3 years after operation. However, they were still significantly lower than the control subject level even at 3 years after operation. CONCLUSIONS: This study suggests that orthognathic surgery improves the bite force and occlusal contact area of patients with prognathous. However, at 3 years from the time of operation, patients had not reached control subject levels.

Ca2+-sensing receptor-mediated regulation of volume-sensitive Cl- channels in human epithelial cells.

Since extracellular Ca2+ or Mg2+ has been reported to modulate swelling-activated Cl- currents, we examined the expression of the G protein-coupled Ca2+-sensing receptor (CaR) and its involvement in the regulation of volume-sensitive Cl- channels in a human epithelial cell line (Intestine 407). Reverse transcriptase-polymerase chain reaction and immunoblotting analysis showed that Intestine 407 cells express CaR mRNA and protein. The swelling-activated whole-cell Cl- current was voltage-independently augmented by extracellular Ca2+ or Mg2+. In addition, Ca2+ or Mg2+ voltage-dependently accelerated the inactivation kinetics of the Cl- current. Neomycin, spermine and La3+ augmented volume-sensitive Cl- currents. However, these CaR agonists failed to affect depolarization-induced inactivation. Intracellular application of GTPgammaS, but not GDPbeta]S, increased the amplitude of the swelling-induced Cl- current without affecting the basal current. The upregulating effect of Ca2+ on the Cl- current amplitude was abolished by either GTPgammaS or GDPbetaS. In contrast, GTPgammaS and GDPbetaS failed to affect the inactivation kinetics of the Cl- current and the accelerating effect of Ca2+ thereon. The Cl- current amplitude was enlarged by stimulation with forskolin, dibutyryl cAMP and IBMX. During the cAMP stimulation, extracellular Ca2+ failed to increase the Cl- current but did accelerate depolarization-induced inactivation. It is concluded that stimulation of the CaR induces upregulation of volume-sensitive Cl- channels via a G protein-mediated increase in intracellular cAMP in the human epithelial cell. However, the accelerating effect of extracellular divalent cations on the inactivation kinetics of the Cl- current is induced by a mechanism independent of the CaR and cAMP.

Volume expansion sensitivity of swelling-activated Cl(-) channel in human epithelial cells.

In human epithelial cell lines, whole-cell swelling-activated Cl(-) current was not directly correlated to cell volume per se, membrane tension or hydrostatic pressure. The current density exhibited a relation described by a Boltzmann function to the square of the cell diameter. Cytochalasin D enhanced the volume sensitivity. These results suggest that the activation mechanism of volume-sensitive Cl(-) channel is related to cytoskeleton-dependent membrane spring energy in human epithelial cells.

[Pulmonary outflow tract reconstruction with autologous tissue during the Ross procedure: right ventricular characteristics in mid-term follow-up].

BACKGROUND: The Ross procedure requires the interposition of prosthetic or homograft extracardiac conduits to establish ventricle-pulmonary artery connection (RV-PA). These materials usually require multiple reoperations because of conduit failure. To avoid the re-replacement of currently available conduits, usage of autologous tissue may be preferable to reconstruct RV-PA connection during the Ross procedure, especially in the pediatric age group. METHOD: Ten patients (mean age 8.7 years, range 2-23) with congenital aortic valve disease underwent the Ross procedure between June, 1996 and July, 1998. To establish RV-PA continuity, autologous aortic wall including aortic valve with a gusset of pericardial tissue was used in six patients, rolled pericardial conduit with fresh pericardial bicuspid valve in three and one direct anastomosis of pulmonary posterior wall onto the right ventricle with a fresh pericardial monocusp valved patch. All patient's postoperative courses were uneventful. All patients were followed up (mean follow-up period: 21.6 +/- 6.6 months) and postoperative right ventricular characteristics, cardio-thoracic ratio (CTR) on chest X-ray and pulmonary valve function were evaluated. RESULTS: Postoperative right ventricular end-diastolic volume, right ventricular ejection fraction and right ventricular end-diastolic pressure did not change significantly (RVEDV: 128 to 113% of normal, RVEF: 56.4 to 51.5%, RVEDP: 5.9 to 10.1 mmHg). Pulmonary regurgitation during follow-up was mild in six patients and moderate in four. However, CTR decreased significantly over time (preop.: 56.5% postop.: 58.5%, late period: 53.4%). CONCLUSION: Our results support the concept of the reconstruction of pulmonary outflow tract without foreign materials during the Ross procedure. Longer follow-up are necessary to define the possible limitation of this technique.

Molecular cloning, water channel activity and tissue specific expression of two isoforms of radish vacuolar aquaporin.

A major membrane intrinsic protein (VM23) in vacuoles of radish (Raphanus) tap root was investigated. The cDNAs for two isoforms of VM23, gamma- and delta-VM23, encode polypeptides of 253 and 248 amino acids, respectively. gamma- and delta-VM23 correspond to the gamma- and delta-TIP (tonoplast intrinsic protein) of Arabidopsis. The deduced amino acid sequences of the two VM23 isoforms were 60% identical. The amino-terminal sequence of gamma-VM23 showed agreement with the direct sequence of the purified VM23, suggesting that gamma-VM23 is the most abundant molecule among the VM23 isoforms. When mRNAs of gamma- and delta-VM23 were injected into Xenopus oocytes, the osmotic water permeability of oocytes increased 6-fold (60 to 200 microns s-1) of the control oocytes. The transcripts of both isoforms were detected in a high level in growing hypocotyls and young leaves, but delta-VM23 was not detected in seedling roots. Light illumination enhanced the transcription of two genes of VM23 in cotyledons and roots but suppressed their expression in hypocotyls the growth of which was inhibited by light. These findings suggest that the expression of VM23 is tightly related to cell elongation.