Biomedical subjects

M Wakui

Publications and source records attributed to M Wakui.

At least 19 recordsLinked to original sources

PubMed2001

Phorbol ester impairs electrical excitation of rat pancreatic beta-cells through PKC-independent activation of KATP channels.

BACKGROUND: Phorbol 12-myristate 13-acetate (PMA) is often used as an activating phorbol ester of protein kinase C (PKC) to investigate the roles of the kinase in cellular functions. Accumulating lines of evidence indicate that in addition to activating PKC, PMA also produces some regulatory effects in a PKC-independent manner. In this study, we investigated the non-PKC effects of PMA on electrical excitability of rat pancreatic beta-cells by using patch-clamp techniques. RESULTS: In current-clamp recording, PMA (80 nM) reversibly inhibited 15 mM glucose-induced action potential spikes superimposed on a slow membrane depolarization and this inhibition can not be prevented by pre-treatment of the cell with a specific PKC inhibitor, bisindolylmaleimide (BIM, 1 microM). In the presence of a subthreshold concentration (5.5 mM) of glucose, PMA hyperpolarized beta-cells in a concentration-dependent manner (0.8-240 nM), even in the presence of BIM. Based on cell-attached single channel recordings, PMA increased ATP-sensitive K+ channel (KATP) activity. Based on inside-out patch-clamp recordings, PMA had little effect on KATP activity if no ATP was in the bath, while PMA restored KATP activity that was suppressed by 10 microM ATP in the bath. In voltage-clamp recording, PMA enhanced tolbutamide-sensitive membrane currents elicited by repetitive ramp pulses from -90 to -50 mV in a concentration-dependent manner, and this potentiation could not be prevented by pre-treatment of cell with BIM. 4alpha-phorbol 12,13-didecanoate (4alpha-PDD), a non-PKC-activating phorbol ester, mimicked the effect of PMA on both current-clamp and voltage-clamp recording configurations. With either 5.5 or 16.6 mM glucose in the extracellular solution, PMA (80 nM) increased insulin secretion from rat islets. However, in islets pretreated with BIM (1 microM), PMA did not increase, but rather reduced insulin secretion. CONCLUSION: In rat pancreatic beta-cells, PMA modulates insulin secretion through a mixed mechanism: increases insulin secretion by activation of PKC, and meanwhile decrease insulin secretion by impairing beta-cell excitability in a PKC-independent manner. The enhancement of KATP activity by reducing sensitivity of KATP to ATP seems to underlie the PMA-induced impairment of beta-cells electrical excitation in response to glucose stimulation.

ATP-Binding Cassette Transporters↗

PubMed2001

Genes highly expressed in the early phase of murine graft-versus-host reaction.

Graft-versus-host reaction (GVHR) is a complex process initiated upon allorecognition. For detection of early molecular events in GVHR, we first assessed time courses with respect to symptoms and serum interferon (IFN)-gamma levels and then used the differential display method to compare gene transcript patterns during the early phase between acute lethal GVHR mice and syngeneic controls. In the GVHR mice, high expression levels of seven genes encoding the following molecules were detected: TGTP/Mg21 (an IFN-gamma-related signaling molecule), vitronectin, Nedd5 (a mammalian septin), manganese superoxide dismutase, activin betaC subunit, PRCC (a papillary renal cell carcinoma-associated molecule), and an uncharacterized gene corresponding to a mouse expressed sequence tag (EST). The expression levels of most genes peaked before the symptomatological onset and the peak of IFN-gamma levels. Thus, gene expression monitoring may characterize the inductive process of GVHR and aid in the development of gene-based diagnostics and therapies.

Animals↗

PubMed2001

Protein kinase C-dependent and -independent inhibition of Ca(2+) influx by phorbol ester in rat pancreatic beta-cells.

Phorbol esters were used to investigate the action of protein kinase C (PKC) on insulin secretion from pancreatic beta-cells. Application of 80 nM phorbol 12-myristate 13-acetate (PMA), a PKC-activating phorbol ester, had little effect on glucose (15 mM)-induced insulin secretion from intact rat islets. In islets treated with bisindolylmaleimide (BIM), a PKC inhibitor, PMA significantly reduced the glucose-induced insulin secretion. PMA decreased the level of intracellular Ca(2+) concentration ([Ca(2+)](i)) elevated by the glucose stimulation when tested in isolated rat beta-cells. This inhibitory effect of PMA was not prevented by BIM. PMA inhibited glucose-induced action potentials, and this effect was not prevented by BIM. Further, 4alpha-phorbol 12,13-didecanoate (4alpha-PDD), a non-PKC-activating phorbol ester, produced an effect similar to PMA. In the presence of nifedipine, the glucose stimulation produced only depolarization, and PMA applied on top of glucose repolarized the cell. When applied at the resting state, PMA hyperpolarized beta-cells with an increase in the membrane conductance. Recorded under the voltage-clamp condition, PMA reduced the magnitude of Ca(2+) currents through L-type Ca(2+) channels. BIM prevented the PMA inhibition of the Ca(2+) currents. These results suggest that activation of PKC maintains glucose-stimulated insulin secretion in pancreatic beta-cells, defeating its own inhibition of the Ca(2+) influx through L-type Ca(2+) channels. PKC-independent inhibition of electrical excitability by phorbol esters was also demonstrated.

Action Potentials↗

PubMed2001

Appendiceal carcinoma invading the urinary bladder.

A case is reported of a 78-year-old woman with appendiceal carcinoma invading the bladder causing irritative symptoms. Although several imaging studies suggested that the secondary bladder tumor was of cecal or appendiceal origin, such as abscess or mucocele, histologic findings on transurethral and transvaginal biopsy were inconclusive. However, following laparotomy, pathologic examination of the frozen sections revealed a mucinous cystadenocarcinoma originating in the appendix and a right hemicolectomy and en bloc partial cystectomy were performed. One year after the operation, the patient was well with no evidence of recurrent cancer.

Aged↗

PubMed2000

Hexamminecobalt(III) chloride inhibits glucose-induced insulin secretion at the exocytotic process.

Hexamminecobalt(III) (HAC) chloride was found to have a potent inhibitory effect on glucose-induced insulin secretion from pancreatic islets. HAC at 2 mm inhibited the secretion in response to 22.2 mm glucose by 90% in mouse islets. Perifusion experiments revealed that the first phase of insulin secretion was severely suppressed and that the second phase of secretion was completely abrogated. Removal of HAC from the perifusate immediately restored insulin secretion with a transient overshooting above the normal level. However, HAC failed to affect glucose-induced changes in d-[6-(14)C]glucose oxidation, levels of reduced forms of NAD and NADP, mitochondrial membrane potential, ATP content, cytosolic calcium concentration, or calcium influx into mitochondria. Furthermore, HAC inhibited 50 mm potassium-stimulated insulin secretion by 77% and 10 microm mastoparan-stimulated insulin secretion in the absence of extracellular Ca(2+) by 80%. The results of a co-immunoprecipitation study of lysates from insulin-secreting betaHC9 cells using anti-syntaxin and anti-vesicle-associated membrane protein antibodies for immunoprecipitation or Western blotting suggested that HAC inhibited disruption of the SNARE complex, which is normally observed upon glucose challenge. These results suggest that the inhibitory effect of HAC on glucose-induced insulin secretion is exerted at a site(s) distal to the elevation of cytosolic [Ca(2+)], possibly in the exocytotic machinery per se; and thus, HAC may serve as a useful tool for dissecting the molecular mechanism of insulin exocytotic processes.

Adenosine Triphosphate↗

PubMed2000

Tumor necrosis factor alpha 5'-flanking region, tumor necrosis factor receptor II, and HLA-DRB1 polymorphisms in Japanese patients with rheumatoid arthritis.

OBJECTIVE: New polymorphisms affecting transcriptional activity were recently reported within the 5'-flanking region of the tumor necrosis factor alpha gene (TNFalpha). In addition, genome-wide linkage screening indicated 1p36 as one of the candidate chromosomal regions where the TNF receptor II gene (TNFR2) is located. In the present study, HLA-DRB1, TNFalpha promoter, and TNFR2 genotypes were determined to examine whether these polymorphisms are associated with rheumatoid arthritis (RA), either independently or in combination. METHODS: Genotypes of HLA-DRB1, TNFalpha upstream promoter, and TNFR2 codon 196 were determined in 545 Japanese patients with RA and 265 healthy controls. Association of these genes with susceptibility to RA was analyzed both independently and after stratification by one of the genotypes. RESULTS: As expected, the HLA-DRB1 shared epitope was strongly associated with RA. In addition, a significant negative association of DRB1*1405 and 1302 was observed. Furthermore, DRB1*1405 was suggested to possess a protective role for the development of RA in DRB1*0405-positive individuals. A significant increase in TNFalpha-U02 in RA was detected, which was not independent of DRB1*0405. A significant association was not observed between TNFR2-196M/R polymorphism and RA. CONCLUSION: Among the 3 genes examined in this study, HLA-DRB1 was considered to be most strongly associated with RA.

Antigens, CD↗

PubMed2000

cAMP-independent decrease of ATP-sensitive K+ channel activity by GLP-1 in rat pancreatic beta-cells.

Using the patch-clamp method, we studied the mechanism of depolarization of rat pancreatic beta-cells induced by glucagon-like peptide 1 (7-36) amide (GLP-1). GLP-1 caused depolarization in a concentration-dependent manner (0.2-100 nM). Exendin (9-39) amide, a GLP-1 receptor antagonist, prevented the GLP-1-induced depolarization. GLP-1 reduced tolbutamide-sensitive membrane currents evoked by voltage ramps from -90 to -50 mV, recorded in the perforated whole-cell configuration, suggesting that GLP-1 decreased the activity of the ATP-sensitive K+ channel (KATP). This GLP-1 effect was prevented by exendin (9-39) amide. In cells treated with Rp-cAMPS, an inhibitor of the cAMP-dependent protein kinase (PKA), GLP-1 still caused depolarization and reduced the whole-cell membrane current through KATP. Examined in the cell-attached configuration, 20 nM GLP-1, applied out of the patch, had little effect on KATP activity. In the inside-out configuration, the open time probability and the single-channel conductance of KATP in the absence of ATP inside the membrane were unaffected by the presence of 20 nM GLP-1 in the pipette. In both conditions, application of ATP to the inside of the membrane reduced KATP activity. The half-maximal concentrations (ki) of ATP were 11.6 microM without and 5.6 microM with 20 nM GLP-1 in the pipette (P<0.05). The values of the Hill coefficient (h) were 1.03 without and 1.01 with GLP-1. We conclude that GLP-1 reduces KATP activity by elevating the sensitivity of KATP to ATP, resulting in depolarization of pancreatic beta-cells. This GLP-1 action is independent of the cAMP signalling pathway.

Action Potentials↗

PubMed2000

Involvement of phosphorylation of beta-subunit in cAMP-dependent activation of L-type Ca2+ channel in aortic smooth muscle-derived A7r5 cells.

We investigated the effect of intracellular cAMP on the gating kinetics of L-type Ca2+ channel in an A7r5 smooth muscle-derived cell line using the whole-cell patch-clamp technique. Application of dibutyryl cyclic AMP (db-cAMP) to the cell increased the magnitude of Ca2+ currents through L-type Ca2+ channels (I(Ca)), and shifted the current-voltage relationship (I-V curve) for I(Ca) to the left. The magnitudes of maximum I(Ca) were 14.1 +/- 0.7 before and 16.0 +/- 1.1 pA/pF after application of 1 mM db-cAMP (P < 0.05). The values of the half-activation potential (V(1/2)) of I(Ca), estimated from activation curves, were -7.0 +/- 0.8 mV before and -10.8 +/- 1.0 mV after application of db-cAMP (P < 0.05). In cells pretreated with 10 microM Rp-cAMPS (a specific inhibitor of PKA), db-cAMP affected neither the I-V curve nor the activation curve for I(Ca). In cells pretreated with the antisense oligonucleotide for the beta-subunit of L-type Ca2+ channel, db-cAMP failed to enhance I(Ca) or alter the activation curve. On the other hand, in the cells pretreated with the nonsense oligonucleotide, application of db-cAMP caused an increase in magnitude of I(Ca) and shifted the activation curve to the left. Western blot analysis revealed that the pretreatment of cells with antisense oligonucleotide but nonsense oligonucleotide reduced the expression of the beta-subunit of the L-type Ca2+ channel. We conclude that the cAMP-dependent phosphorylation of the beta-subunit potentiates the voltage dependency of the activation kinetics of the L-type Ca2+ channel in A7r5 cells.

Animals↗

PubMed2000

Risk-adapted pre-emptive therapy for cytomegalovirus disease in patients undergoing allogeneic bone marrow transplantation.

We prospectively evaluated a risk-adapted pre-emptive treatment with ganciclovir for CMV diseases in patients undergoing allogeneic bone marrow transplantation (BMT). High-level CMV antigenemia (10 or more positive cells on two slides) or CMV antigenemia at any level in patients with grade II-IV acute graft-versus-host disease (aGVHD) were chosen as risk factors. We also retrospectively evaluated virus reactivation in plasma using quantitative real-time polymerase chain reaction (PCR). Fifty patients were evaluable. None of the 27 patients with or without grade I aGVHD developed high-level CMV antigenemia or CMV disease. Among the 23 patients with grade II-IV aGVHD, 12 patients (52%) developed CMV antigenemia and were treated pre-emptively, of whom two developed CMV gastroenteritis or retinitis in spite of therapy. Six of the remaining 11 patients developed CMV gastroenteritis before CMV antigenemia was detectable. All of the eight patients with CMV diseases were successfully treated with ganciclovir and no deaths directly related to CMV disease occurred. In four of the seven evaluable patients with CMV gastroenteritis, real-time PCR was able to detect virus reactivation earlier than CMV antigenemia. Although our risk-adapted pre-emptive therapy effectively reduced CMV-related mortality, further refinements of this approach, particularly in the prevention of CMV gastroenteritis, may be achieved by incorporating real-time PCR.

Adolescent↗

PubMed2000

Urinary tract cancer screening through analysis of urinary red blood cell volume distribution.

BACKGROUND: Hematuria is differentiated between glomerular and urinary tract origins on the basis of urinary red cell morphology. We used this distinction in a program of mass screening for urinary tract cancer to achieve cost-effective and safe hematuria screening. METHODS: Of a total of 21372 adults (mean age 52.3 years; range 20-79 years) participating in a health screening, 912 (4.3%) had a positive dipstick for hematuria and were enrolled in the present study. Urinary red cell volume distribution curves (RDC), the simplest method of assessing urinary red cell morphology, were calculated and subjects were divided into two groups based on their RDC patterns. Group I subjects had a normocytic or mixed pattern and they were immediately investigated for urinary tract malignancy because of the associated risk for urological disease. Group II subjects had a microcytic pattern and, therefore, were judged to be at a low risk of urologic malignancy and were followed up 3 years later without urologic investigations. RESULTS: Among the 38 subjects in group I (4% of all dipstick-positive subjects), one case of bladder cancer was detected. In the remaining 37 patients, 15 cases of benign diseases were discovered. Group II was composed of 869 subjects (96%). The inquiry into their health status conducted 3 years later revealed that 831 (95.6%) were healthy and, of these, 13 had experienced gross hematuria during the period but urological malignancies were ruled out by their urologists, two (0.2%) had died of diseases other than urological cancer and 36 (4.1%) were lost to follow-up. With our method, total costs have been reduced by 93.8% against a conventional setting of a full evaluation for all cases of hematuria. CONCLUSIONS: Microcytic hematuria, accounting for 96% of asymptomatic microhematuria cases in the present study, was not associated with a risk for urinary tract malignancy. Compared with conventional hematuria screening with a complete work-up of all cases of hematuria, investigating only subjects with mixed or normocytic RDC patterns was safe and cost effective.

Adult↗

PubMed2000

Metallic stents for malignant and benign ureteric obstruction.

OBJECTIVE: To report our experience of using metallic stents to treat ureteric obstruction caused by malignant or benign disease. PATIENTS AND METHODS: Nine patients with obstruction in 11 ureters caused by malignant or benign disease (mean age 61 years, range 35-82, mean follow-up 7 months, range 3-11) were treated using metallic stents. A balloon-expandable metallic stent was used in one patient and self-expandable metallic stents in the remaining eight. All stents were inserted via a percutaneous antegrade approach. RESULTS: Of the 11 ureters, nine remained patent with no further manipulation during the follow-up of 3-11 months. An additional stent was placed in continuity with the first in two ureters of two patients at 4 and 5 weeks after the first procedure because of persistent obstruction. After the second intervention, their obstruction was improved. Transient vesico-ureteric reflux occurred in two of three stented distal ureters, but the reflux resolved spontaneously within 2 months after stent implantation. Ureteric patency was maintained in all patients and no major complications related to stenting occurred during the follow-up. Two patients died from cervical cancer at 3 and 5 months after stenting. CONCLUSION: In patients with difficult ureteric obstructions a metallic stent provides a safe and effective alternative to an indwelling double-pigtail catheter or percutaneous nephrostomy.

Aged↗

PubMed2000

2-Aminoethoxydiphenyl borate modulates kinetics of intracellular Ca(2+) signals mediated by inositol 1,4,5-trisphosphate-sensitive Ca(2+) stores in single pancreatic acinar cells of mouse.

Regulation of the kinetics of intracellular Ca(2+) signals with a novel, membrane-penetrable, inositol 1,4,5-trisphosphate (InsP(3)) receptor/Ca(2+) channel modulator, 2-amino-ethoxydiphenyl borate (2APB), has been investigated using patch-clamp, whole-cell recording to monitor Ca(2+)-activated Cl(-) currents in single isolated pancreatic acinar cells. 2APB itself fails to evoke a detectable current response but it dramatically changes the kinetics of agonist-induced Ca(2+) release from pulsatile spikes to long-lasting, huge Ca(2+) waves, suggesting that 2APB coordinates local Ca(2+) release to generate global Ca(2+) signals. The regulation by 2APB can be elicited by internal perfusion of InsP(3) in a concentration-dependent manner, indicating that this regulation is not mediated through membrane receptors or G protein signal transduction. The InsP(3) receptor blocker heparin, but not the ryanodine-sensitive receptor blockers ruthenium red or ryanodine, abolishes 2APB-mediated regulation of Ca(2+) release. This results also suggest that 2APB effects are mediated through InsP(3) receptors. 2APB substantially modifies single inward Cl(-) current pulse evoked by the photolytic release of caged InsP(3) but not by caged Ca(2+). These data indicate that 2APB-induced regulation is mediated neither by Ca(2+)-induced Ca(2+) release nor by affecting Cl(-) channel activity directly. We conclude that 2APB regulates the kinetics of intracellular Ca(2+) signals, represented as the change in the Ca(2+) oscillation patterns from brief pulsatile spikes to huge, long-lasting Ca(2+) waves. Moreover, this regulation seems to be mediated through InsP(3)-sensitive Ca(2+) pools. 2APB may act as a novel, useful pharmacological tool to study the genesis of intracellular Ca(2+) signals.

Animals↗

PubMed2000

Protein kinase C-dependent inhibition of K+ currents in noradrenaline-induced depolarization of smooth muscle of guinea-pig vas deferens.

Ionic mechanisms and signal transduction underlying noradrenaline (NA)-induced depolarization in single smooth muscle cells of guinea-pig vas deferens were studied. NA caused depolarization followed by action potentials through activation of 1-adrenoceptors. In the presence of nifedipine, no action potential was generated, and the magnitude of the depolarization depended on the concentration of NA (0.1-100 micrometer). NA, through 1-adrenoceptor activation, reduced the magnitude of membrane currents in response to voltage ramp pulses from -90 to -30 mV in a concentration-dependent manner. The reversal potential of the current inhibited by NA changed proportionally to the change in the equilibrium potential of K+, suggesting that NA inhibited K+ channel activity. Treatment of cells with GDPS, an inhibitor of G proteins, or bisindolylmaleimide (BIM), a selective protein kinase C (PKC) inhibitor, prevented the NA inhibition of the currents. Application of 12-O-tetradecanoylphorbol 13-acetate (TPA), an activator of PKC, mimicked the effect of NA. It is suggested that in the smooth muscle of guinea-pig vas deferens, activation of 1-adrenoceptors and the subsequent activation of PKC led to inhibition of K+ currents, which is responsible for the depolarization induced by NA.

Adrenergic alpha-Agonists↗

PubMed1999

NADH shuttle system regulates K(ATP) channel-dependent pathway and steps distal to cytosolic Ca(2+) concentration elevation in glucose-induced insulin secretion.

The NADH shuttle system is composed of the glycerol phosphate and malate-aspartate shuttles. We generated mice that lack mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH), a rate-limiting enzyme of the glycerol phosphate shuttle. Application of aminooxyacetate, an inhibitor of the malate-aspartate shuttle, to mGPDH-deficient islets demonstrated that the NADH shuttle system was essential for coupling glycolysis with activation of mitochondrial ATP generation to trigger glucose-induced insulin secretion. The present study revealed that blocking the NADH shuttle system severely suppressed closure of the ATP-sensitive potassium (K(ATP)) channel and depolarization of the plasma membrane in response to glucose in beta cells, although properties of the K(ATP) channel on the excised beta cell membrane were unaffected. In mGPDH-deficient islets treated with aminooxyacetate, Ca(2+) influx through the plasma membrane induced by a depolarizing concentration of KCl in the presence of the K(ATP) channel opener diazoxide restored insulin secretion. However, the level of the secretion was only approximately 40% of wild-type controls. Thus, glucose metabolism through the NADH shuttle system leading to efficient ATP generation is pivotal to activation of both the K(ATP) channel-dependent pathway and steps distal to an elevation of cytosolic Ca(2+) concentration in glucose-induced insulin secretion.

Animals↗

PubMed1999

Prospective evaluation for upper gastrointestinal tract acute graft-versus-host disease after hematopoietic stem cell transplantation.

The incidence and clinical significance of upper gastrointestinal tract acute graft-versus-host disease (upper GI GVHD) were prospectively evaluated in 44 Japanese patients who underwent allogeneic (n = 26) or autologous (n = 18) stem cell transplantation. Endoscopic examination was routinely performed between days 20 and 50 post-transplant and when symptoms of upper GI and/or acute GVHD of other organs were present. The results were compared with the historical records of 49 allograft and 20 autograft recipients. The diagnosis of upper GI GVHD was confirmed by histologic findings of GVHD and persistent upper GI tract symptoms. The incidence of upper GI GVHD was 46% in the prospective allograft group, higher than in the retrospective group. Upper GI GVHD was not diagnosed in any autograft patients. Twelve of 19 patients with upper GI GVHD had skin GVHD, and two of the 12 had concurrent lower GI GVHD. Upper GI GVHD was successfully treated with steroids and did not progress to symptomatic lower GI GVHD. In addition, upper GI GVHD completely resolved without specific alteration in immunosuppressant therapy in six patients. No risk factors for upper GI GVHD could be identified. The presence of upper GI GVHD did not significantly affect early death rate, incidence of chronic GVHD, and overall survival. In conclusion, by the prospective evaluation of the upper GI tract by endoscopy we could accurately diagnose upper GI GVHD in half our allogeneic recipients. However, upper GI GVHD was successfully controlled with or without additional steroids in all cases and had little impact on transplant outcome.

Adolescent↗

PubMed1999

Treatment of advanced myelodysplastic syndrome with a regimen including recombinant human granulocyte colony-stimulating factor preceding allogeneic bone marrow transplantation.

We treated 13 patients with morphologically advanced myelodysplastic syndrome using cytosine arabinoside and total body irradiation, followed by allogeneic marrow transplantation from HLA-identical sibling donors. Granulocyte colony-stimulating factor (G-CSF) was added to the preparative regimen to selectively increase chemosensitivity of leukaemic cells and to improve transplant outcome. No regimen-related deaths occurred, and no side-effects related to the addition of G-CSF were observed except for transient mild bone pain. At a median follow-up time of 39 months the projected 5-year disease-free survival and 5-year overall survival were 67.7% and 75.5%, respectively, with only one case showing cytogenetic relapse. The preparative regimen including G-CSF is feasible, and preliminary results seem to be encouraging. However, a larger trial is clearly warranted to evaluate its efficacy.

Adolescent↗

PubMed1999

Dry eye after haematopoietic stem cell transplantation.

AIMS: To determine the incidence, natural course, and severity of dry eye occurring or worsening after haematopoietic stem cell transplantation (SCT). METHODS: At a tertiary care hospital, 53 patients undergoing allogeneic or autologous SCT followed by at least 180 days of follow up were studied prospectively. Examination included grading of symptoms of dry eye, evaluation of ocular surface, tear break up time, and Schirmer tests with and without nasal stimulation. Meibomian gland secretion was also examined using a slit lamp while applying steady digital pressure. RESULTS: Of the 53 patients, 44 received allografts. Half of these patients (22) developed dry eye or their pre-existing dry eye worsened after SCT, while none of nine autograft recipients did. Onset of dry eye was 171 (SD 59) days after SCT. Two types of dry eye occurred. One (n=10) was severe with ocular surface findings resembling Sjögren's syndrome and reduction of reflex tearing soon after onset. A mild type (n=12) had unimpaired reflex tearing. Meibomian gland dysfunction (MGD) was more frequent and severe in patients with dry eye and chronic graft versus host disease (GVHD), and overall severity of dry eye was greater in patients with MGD and chronic GVHD. CONCLUSIONS: Dry eye after SCT occurred only in allograft recipients, and was not evident in autograft recipients. The severe form of dry eye had a tendency to develop rapidly. Further study on the prediction and treatment of severe dry eye after SCT is necessary.

Adult↗

PubMed1999

Corticotropin-releasing factor modulation of Ca2+ influx in rat pancreatic beta-cells.

The effects of corticotropin-releasing factor (CRF) on the intracellular concentration of Ca2+ were studied in isolated single beta-cells of the rat islet. Immunohistochemical staining using CRF-receptor antibodies revealed the presence of both type 1 (CRF-R1) and type 2 (CRF-R2) receptors for CRF in the majority of islet cells. CRF (2 nmol/l) increased cytosolic Ca2+ concentration under 2.8 mmol/l glucose, dependent upon extracellular Ca2+. CRF caused depolarization of the cell membrane, which was followed by action potentials under 2.8 mmol/l glucose. The dose-response relationships of CRF-induced depolarization in the presence of 1 micromol/l nifedipine produced a bell-shaped curve, showing the peak response at 2 nmol/l. In the whole-cell patch-clamp recording, CRF enhanced Ca2+ currents through L-type Ca2+ channels in a dose-dependent manner similar to that for depolarization. In cells pretreated with Rp-deastereomer of adenosine cyclic 3',5'-phosphorothiolate (100 micromol/l), neither depolarization nor an increase in the Ca2+ current was caused by CRF at concentrations <2 nmol/l. In these cells, CRF at 20 nmol/l reduced the Ca2+ current. These results suggest that in single beta-cells of rat islets, CRF, through its own receptor, potentiates Ca2+ influx through the L-type Ca2+ channel by activation of the cAMP/protein kinase A signaling pathway. CRF at a high concentration also shows an inhibitory effect on the Ca2+ current through an unknown signaling pathway.

Animals↗