Skewed abrogation of tolerance to a neo self-antigen in double-transgenic mice coexpressing the antigen with interleukin-1beta or interferon-gamma

Transgenic (Tg) mice expressing hen egg lysozyme (HEL) under the control of the alphaA-crystallin promoter exhibit tolerance to HEL by both their T- and B-cell compartments. Here, we show that double-Tg mice, coexpressing HEL with either interleukin-1beta or interferon (IFN)-gamma, demonstrated unresponsiveness to HEL by their T-cell compartment, but most of them developed antibodies against HEL following a challenge with the antigen. The abrogation of humoral tolerance was more pronounced in the HEL/IL-1 double-Tg mice than in the HEL/IFN-gamma mice. Unlike their controls, double-Tg mice exhibited remarkable levels of variability in their antibody levels. The skewed abrogation of tolerance in the double-Tg mice is proposed to be due to the cytokines' capacity to rescue from clonal deletion small numbers of T cells, which provide help to antibody producing B cells. This notion is supported by the finding that adoptive transfer of small numbers of Th1 or Th2 cells into HEL-Tg mice made possible antibody production similar to that seen in the double-Tg mice.

Mechanism of induction of transforming growth factor-beta type II receptor gene expression by v-Src in murine myeloid cells

Transforming growth factor (TGF)-beta1 plays an important role during hematopoiesis. Previously, we had shown that the growth of a v-Src-transformed myeloid cell line was markedly more inhibited by TGF-beta treatment when compared with the wild-type myeloid cell line. To investigate the increased growth sensitivity of the v-Src-transformed myeloid cell line, 32D-src, to TGF-beta, we examined expression of the TGF-beta type II receptor (TGF-beta RII) gene in myeloid cell lines. Northem blot analysis showed that expression of approximately 8- and 6-kb species of TGF-beta RII transcripts was markedly increased in the 32D-src cell line. The expression of the TGF-beta RII promoter linked to a reporter gene was increased 23-fold by v-Src. DNA transfection and electrophoretic mobility shift assay revealed that v-Src induces TGF-beta RII promoter activity through an AP1/ATF2-like sequence (-219 to -172), ETS binding sites (+1 to +36), and the inverted CCAAT box (-81 to -77). Novel DNA-protein complexes with ETS binding sites are significantly increased in v-src-transformed cell lines compared with the control cell line. These results suggest that v-Src induces activity of the TGF-beta RII promoter through multiple elements by inducing expression of nuclear proteins interacting with these elements.

Mutation in hepatocyte nuclear factor-1alpha is not a common cause of MODY and early-onset type 2 diabetes in Korea

Maturity-onset diabetes of the young (MODY)-3 with a mutation in hepatocyte nuclear factor (HNF)-1alpha has been identified in most races, but the prevalence of Korean MODY and early-onset type 2 diabetes with a mutation in this gene is unknown. To determine the prevalence of MODY and early-onset type 2 diabetes with the mutation of HNF-1alpha gene in Korea, we analyzed this gene in 69 Korean early-onset type 2 diabetics and in 35 healthy persons using the single-strand conformation polymorphism (SSCP) technique and direct sequencing. We identified one mutation in exon 4 (C900A) in only one of the 69 Korean subjects with early-onset type 2 diabetes; this mutation was silent and did not change the amino acid (Pro300). Additionally, we identified four polymorphisms: S487N, AAC-->AGC, intron 2 (nt -23), intron 7: (nt +7) and intron 9 (nt -24). However, there was no significant difference in frequencies of the four polymorphisms between the type 2 diabetes and control groups. Among type 2 diabetics, codon 487 variant showed no relationship to age at onset, body mass index, fasting blood glucose, HbA1c, lipid profile, basal C-peptide and 2 hour C-peptide. We concluded that this genetic mutation in HNF-1alpha gene may not be a common contributor to MODY and early-onset type 2 diabetes susceptibility in Korea.

Expression of interleukin-8 correlates with angiogenesis, tumorigenicity, and metastasis of human prostate cancer cells implanted orthotopically in nude mice

We determined whether the expression of interleukin-8 (IL-8) by human prostate cancer cells correlates with induction of angiogenesis, tumorigenicity, and production of metastasis. Low and high IL-8-producing clones were isolated from the heterogeneous PC-3 human prostate cancer cell line. The secretion of IL-8 protein correlated with transcriptional activity and levels of IL-8 mRNA. All PC-3 cells expressed both IL-8 receptors, CXCR1 and CXCR2. The low and high IL-8-producing clones were injected into the prostate of nude mice. Titration studies indicated that PC-3 cells expressing high levels of IL-8 were highly tumorigenic, producing rapidly growing, highly vascularized prostate tumors with and a 100% incidence of lymph node metastasis. Low IL-8-expressing PC-3 cells were less tumorigenic, producing slower growing and less vascularized primary tumors and a significantly lower incidence of metastasis. In situ hybridization (ISH) analysis of the tumors for expression of genes that regulate angiogenesis and metastasis showed that the expression level of IL-8, matrix metalloproteinases, vascular endothelial growth factor (VEGF), and E-cadherin corresponded with microvascular density and biological behavior of the prostate cancers in nude mice. Collectively, the data show that the expression level of IL-8 in human prostate cancer cells is associated with angiogenesis, tumorigenicity, and metastasis.

Identification and characterization of multiple isoforms of a mouse ribosome receptor

We isolated multiple cDNA clones encoding various isoforms of a mouse ribosome receptor protein (mRRp). The cDNAs were isolated from a 13.5-day-old mouse conceptus cDNA library by polymerase chain reaction-based screening. The predicted proteins encoded by these cDNAs showed significant homology with ribosome receptors present in dogs (83%), humans (80%), and chickens (45%). The cDNA isoforms had highly identical N- and C-terminal sequences but differed in their central sequences, suggesting that these cDNA isoforms may be derived by alternative splicing from a single gene. Genomic Southern blot analysis confirmed the existence of only a single mouse ribosome receptor gene. Alignments of the deduced amino acid sequences of the mRRp cDNA isoforms revealed that they differ in the number of decapeptide repeats present in the central domain of the protein. These repeats have been previously suggested to mediate ribosome binding and thus differences in repeat number may translate to different ribosome binding abilities. The longest mRRp isoform had 61 tandem repeats. This is of interest because in the human and canine ribosome receptor proteins there are only 54 tandem repeats, suggesting that humans and dogs may also have larger ribosome receptor protein isoforms. Surprisingly, mRRp has a very short basic C-terminal sequence of only 35 amino acids, while in contrast, the known human and canine forms of this protein have acidic C-terminal regions comprised of 803 and 798 amino acid residues, respectively. Although the function of the C-terminal region is currently unknown, it may be that those C-terminal sequences that are present in human and canine RRp proteins but missing in mRRp do not play critical roles in RRp function. The cDNA of the ES/130 isoform, which lacks tandem repeats and presumably are unable to bind ribosomes, could be isolated by reverse transcriptase-PCR from E 13.5 mouse embryos. mRRp mRNAs were expressed in all tissues examined but expression levels of each isoform differed between tissues. The identification of multiple mRRp isoforms in the mouse will allow us to study the regulation and function of ribosome receptors on a genetic level.

Proteome analysis of light-induced proteins in Synechocystis sp. PCC 6803: identification of proteins separated by 2D-PAGE using N-terminal sequencing and MALDI-TOF MS

The cyanobacterium Synechocystis sp. PCC 6803 is an ideal model organism for the proteome study of light-induced gene expression because the whole genomic sequence has been determined. The soluble proteins extracted from light- and dark-cultured cells were separated by two-dimensional polyacrylamide gel electrophoresis. Light-induced protein spots electroblotted on a polyvinyldiene difluoride membrane were analyzed by N-terminal Edman sequence determination and followed by CyanoBase. The tryptic digests of some proteins were also confirmed by matrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) and MS-Fit search. Interestingly, eight proteins were related to photosynthesis and respiration (RbcS/L, CbbA, Gap2, AtpB, CpcB, PsbO, and PsbU). Four proteins (SodB, DnaK, GroEL2, and Tig) were involved in cellular processes and the functions of another two proteins (rehydrin and membrane protein) were unknown. The proteome analysis by N-terminal Edman sequencing and MALDI-TOF enabled us to characterize one-shot protein profiles expressed under different physiological conditions.

Clinical results of the transjugular intrahepatic portosystemic shunt (TIPS) for the treatment of variceal bleeding

BACKGROUND

Transjugular intrahepatic portosystemic shunt (TIPS) has been popularized for the treatment of refractory variceal bleeding. The aim of this study was to assess the safety and long-term effect of TIPS in the treatment of variceal bleeding that is not controlled with pharmacological and endoscopic treatment.

METHODS

Thirty-six patients who underwent transjugular intrahepatic portosystemic shunt (TIPS) due to refractory variceal bleeding were included in the study. The effectiveness of portal decompression and bleeding control was evaluated. Upper gastrointestinal endoscopy was performed to analyse the degree of varices and portal hypertensive gastropathy (PHG) before TIPS procedure and one to three weeks after TIPS. Angiography was performed in surviving patients, if bleeding recurred, or if ultrasonography or endoscopy suggested stent dysfunction.

RESULTS

TIPS were successfully placed in 36 of 38 patients (94.6%). TIPS achieved hemostasis of variceal bleeding in 34 patients (94.4%). Portal venous pressure decreased from an initial average of 28.7 +/- 7.9 to 23.2 +/- 9.4 mmHg after TIPS (p < 0.05). The portosystemic pressure gradient was significantly decreased from 15.5 +/- 6.3 to 7.8 +/- 4.1 mmHg (p < 0.01). The degree of esophagogastric varices and PHG was significantly improved after TIPS. The total length of follow-up was from one day to 54 months (mean: 355 days). The actuarial probability of survival was 83% at one year and 74% at two years. Overall, 16 episodes of stent dysfunction were diagnosed during follow-up. Stent revision by means of angioplasty was successfully performed in 14 of these episodes.

CONCLUSION

TIPS is an effective and reliable nonoperative means of lowering portal pressure. This procedure has proved useful in the management of acute variceal bleeding refractory to endoscopic treatment. Surveillance by ultrasonography, endoscopy, and angiographic intervention is useful for the maintenance of shunt patency.

Bleeding Dieulafoy's lesions and the choice of endoscopic method: comparing the hemostatic efficacy of mechanical and injection methods

BACKGROUND

Dieulafoy's lesion has unique endoscopic and histopathologic characteristics. This is a clinical trial of endoscopic therapy in 24 patients with Dieulafoy's lesions.

METHODS

Patients were divided into 2 groups according to initial endoscopic treatment method. Data were analyzed with respect to clinical and endoscopic characteristics as well as outcomes. The 24 patients were evenly divided into mechanical (9 hemoclipping, 3 band ligation) and injection groups (12).

RESULTS

The average number of therapeutic endoscopic sessions needed to achieve permanent hemostasis for the mechanical and injection groups were 1.17 and 1.67, respectively. Initial hemostasis was achieved in 91.7% of patients undergoing mechanical therapy and 75% of those undergoing injection therapy, with none in the former group needing subsequent surgery in comparison to 17% of the latter group. The rate of recurrent bleeding in the mechanical therapy group was significantly lower in comparison to the injection therapy group (8.3% versus 33.3%, p < 0. 05).

CONCLUSIONS

Higher efficacy in terms of initial hemostasis and less recurrent bleeding was achieved by mechanical hemostatic therapy with hemoclip and band ligation compared with injection therapy. Endoscopic mechanical therapy is recommended as effective for bleeding Dieulafoy's lesions.

Combined periodontal-prosthodontic treatment of early-onset periodontitis--an alternative to implant therapy

A variety of treatment systems should be available for patients whose dentitions are seriously compromised so that they may select customized treatment modalities that satisfactorily restore occlusal function, consider systemic conditions, and lessen the surgical and financial burdens. These requirements become more demanding when clinicians are faced with advanced cases of rapidly progressive periodontitis. Therefore, it is critical to establish sophisticated multidisciplinary treatment modalities for the successful management of these compromised patients. Obviously, because of various limitations, implant therapy cannot be the only solution. This article reports on the successful long-term management of seriously compromised early-onset periodontitis by a combined periodontal-prosthetic treatment as an alternative to implant therapy.

Development of pulmonary arteriovenous fistulas after bidirectional cavopulmonary shunt

BACKGROUND

A high incidence of pulmonary arteriovenous fistulas (PAVF) has been reported after bidirectional cavopulmonary shunt (BCPS) or total cavopulmonary shunt (TCPS; BCPS in patients with interrupted inferior vena cava). However, the definite diagnostic criteria or standard diagnostic modality of PAVF has not yet been defined. The goal of this study was to evaluate the diagnostic modalities and the prevalence of PAVF.

METHODS

We selected 10 patients with TCPS and 27 patients with BCPS. Lung perfusion scan, contrast echocardiogram, and pulmonary angiogram were performed. The results were compared among groups of patients and among each diagnostic modality.

RESULTS

All 10 patients with TCPS and 16 and 13 patients with BCPS showed positive results on contrast echocardiograms and lung scans, respectively. Six patients with TCPS and 4 patients with BCPS showed positive results on pulmonary angiograms. All patients with TCPS developed subclinical or clinical PAVF and 19 patients with BCPS developed subclinical PAVF and none of them had clinical PAVF during the short-term follow-up.

CONCLUSIONS

Most patients with bidirectional cavopulmonary anastomosis have subclinical evidence of right-to-left intrapulmonary shunting. This problem can be demonstrated with various diagnostic modalities.

Inhibitory effects of cimicifugae rhizoma extracts on histamine, bradykinin and COX-2 mediated inflammatory actions

Rhizoma Cimicifugae (RC) has been used traditionally to treat pain and inflammation in Korea. The present study was conducted to gain insights into the mechanism of action regarding analgesic and antiinflammatory activities of RC extracts. RC was first extracted with methanol. The methanol extract (A) was fractionated to an ether-soluble fraction (B) and a water-soluble fraction (C). Fraction C was fractionated to a butanol-soluble fraction (D) and a water-soluble fraction (E). Each fraction (100 mg/kg, i.p.) was tested for analgesic and antiinflammatory activities. Administration of fractions A and D caused dramatic analgesic effects based on acetic acid writhing and tail-flick assays. However, fraction E had an analgesic effect only based on the acetic acid writhing assay. Fractions A, D and E exerted antiinflammatory effects on the rat paw oedema assay. The fractions A, D, E had an inhibitory action on the bradykinin/histamine-mediated contractions of guinea-pig ileum. In addition, fractions A, D and E had the ability to inhibit the production of LPS-induced 6-keto-PGF1alpha production in macrophage cultures. Taken together, these results provide scientific evidence that RC extracts exert analgesic and antiinflammatory effects by inhibiting bradykinin/histamine mediated actions and inhibiting 6-keto-PGF1alpha induction.

Water extract of 1:1 mixture of Phellodendron cortex and Aralia cortex has inhibitory effects on oxidative stress in kidney of diabetic rats

Enhanced activity of the lipid peroxidation and oxidative damages have been implicated in the pathogenesis of diabetic kidney complications. We explored to determine whether these changes in diabetic kidney could be prevented by water extract of mixture of Phellodendron cortex and Aralia cortex (P55A). Greatly elevated content of thiobarbituric acid reactive substances (TBARS) and carbonylated protein in kidneys of diabetic rats were significantly reduced by P55A treatment. In addition, abnormally low ratio of GSH/GSSG in diabetic kidneys was elevated to almost normal levels by the treatment with P55A. These results suggest that P55A extracts exert antioxidant effect by reducing lipid peroxidation and protein carbonylation as well as by elevating the ratio of GSF/GSSG in diabetic kidney.

Clinics in diagnostic imaging (56). Cavernous vascular malformation with intracerebral haematoma

A 28-year-old woman presented following a seizure. Physical and neurological examinations showed no significant abnormality except a drowsy mental state. Routine laboratory studies were normal. Emergency MR imaging showed a rounded, high signal intensity lesion with a focal eccentric heterogeneous signal focus in the right frontal lobe. The heterogeneous focus revealed an irregular low signal rim on T1- and T2-weighted images. Mild surrounding parenchymal oedema was noted. The eccentric focus showed some central enhancement. The diagnosis of cavernous vascular malformation with intracerebral haematoma was confirmed at surgery. The combination of typical MR imaging findings, with clinical and family histories consistent with cavernous angiomata provides sufficient conclusive evidence.

A novel mitochondrial septin-like protein, ARTS, mediates apoptosis dependent on its P-loop motif

Here we describe a protein product of the human septin H5/PNUTL2/CDCrel2b gene, which we call ARTS (for apoptosis-related protein in the TGF-beta signalling pathway). ARTS is expressed in many cells and acts to enhance cell death induced by TGF-beta or, to a lesser extent, by other apoptotic agents. Unlike related septin gene products, ARTS is localized to mitochondria and translocates to the nucleus when apoptosis occurs. Mutation of the P-loop of ARTS abrogates its competence to activate caspase 3 and to induce apoptosis. Taken together, these observations expand the functional attributes of septins previously described as having roles in cytokinesis and cellular morphogenesis.

Hypersensitivity pneumonitis caused by Fusarium napiforme in a home environment

BACKGROUND

We report a case of hypersensitivity pneumonitis (HP) in a 17-year-old male student caused by Fusarium napiforme found in his home environment.

METHODS

The patient was diagnosed according to history, chest radiograph, spirometry, high-resolution chest CT, and transbronchial lung biopsy. To identify the causative agent, cultured aeromolds were collected by the open-plate method. From the main fungi cultured, fungal antigens were prepared, and immunoblot analysis with the patient's serum and each fungal antigen was performed.

RESULTS

Five fungal species were isolated from the patient's home. Immunoblotting analysis with the patient's serum demonstrated more than 10 IgG-binding fractions to F. napiforme extract only, while little binding was noted with the other fungal antigens.

CONCLUSIONS

We should be aware that HP may be caused by F. napiforme in the home environment.

The clinical significance of upper gastrointestinal endoscopy in gastrointestinal vasculitis related to scrub typhus

BACKGROUND AND STUDY AIMS

Scrub typhus is an acute febrile illness caused by Rickettsia tsutsugamushi-induced vasculitis, which is common in Asia and the Pacific islands and is sometimes encountered in Western countries because of increased travel and economic changes spurred by world globalization. Skin rash and eschar are typical physical findings on the trunk and extremities, but endoscopic mucosal changes have not been described in the gastrointestinal tract until now. We aimed to describe different endoscopic characteristics of the gastrointestinal manifestation of scrub typhus, to ascertain the necessity for endoscopy, and to determine correlations between the degrees of endoscopic lesion and clinical severity, including cutaneous manifestation.

PATIENTS AND METHODS

Between January 1993 and October 1998, out of 256 scrub typhus patients, we applied esophagogastroduodenoscopy to 58 patients who complained of gastrointestinal symptoms but had no past history of these symptoms. We categorized clinical severity into four grades according to the degree of six clinical indicators of systemic complications, and endoscopic findings were graded from I to IV (I, normal, nonspecific hyperemia; II, distinct hyperemia, petechiae, purpura; II, superficial hemorrhage, erosion; IV, ulcer, active bleeding).

RESULTS

Endoscopic findings of scrub typhus were characterized by petechiae, superficial hemorrhage, erosion, ulcers, and vascular bleeding (grade I, 14 patients; grade II, 11 patients; grade III, 16 patients; grade IV, 17 patients). In 83.3% of patients there was multiple occurrence of lesions without any predilection sites. Clinical severity was graded (grade I, 7 patients; grade II, 23 patients; grade III, 22 patients; grade IV, 6 patients). There was a correlation between clinical severity and endoscopic findings (P < 0.01). The grade of lesion was high in patients with cutaneous lesions (r(s) 0.359, P < 0.01). In two cases of gastric vascular bleeding, complete hemostasis was achieved by endoscopic hemoclipping.

CONCLUSIONS

The major endoscopic features that can develop in scrub typhus are superficial mucosal hemorrhage, multiple erosions and ulcers without any predilection sites, and unusual vascular bleeding. The endoscopic features are related to cutaneous lesions and severity of the disease. Endoscopy is useful for diagnosis and management of gastrointestinal vasculitis related to scrub typhus.

Background nonselective cationic current and the resting membrane potential in rabbit aorta endothelial cells

The ion channel conductances that regulate the membrane potential was investigated by using a perforated patch-clamp technique in rabbit aorta endothelial cells (RAECs). The whole-cell current/voltage (I-V) relation showed a slight outward rectification under physiological ionic conditions. The resting membrane potential was -23.3 +/- 1.1 mV (mean +/- SEM, n = 19). The slope conductances at the potentials of -80 and 50 mV were 31.0 +/- 4.0 and 62.8 +/- 7.1 pS pF(-1), respectively (n = 15). Changes in the extracellular and intracellular Cl(-) concentrations did not affect the reversal potential on I-V curves. The background nonselective cationic (NSC) current was isolated after the K(+) current was suppressed. The relative permeabilities calculated from the changes in reversal potentials using the constant-field theory were P(K):P(Cs):P(Na):P(Li) = 1:0.87:0.40:0.27 and P(Cs):P(Ca) = 1:0.21. Increases in the external Ca(2+) decreased the background NSC current in a dose-dependent manner. The concentration for half block by Ca(2+) was 1.1 +/- 0.3 mM (n = 7). Through the continuous recording of the membrane potential in a current-clamp mode, it was found that the background NSC conductance is the major determinant of resting membrane potential. Taken together, it could be concluded that the background NSC channels function as the major determinant for the resting membrane potential and can be responsible for the background Ca(2+) entry pathway in freshly isolated RAECs.

Expression of tissue inhibitors of metalloproteinases (TIMPs) in hepatocellular carcinoma

BACKGROUND

Matrix metalloproteinases (MMPs) have been implicated in the remodelling of extracellular matrix (ECM), including basement membrane. ECM remodelling is associated with pathological processes, including hepatic fibrosis, tumor invasion and metastasis. Tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 were known to inhibit MMP-9 and MMP-2, respectively. In the present study, we examined the expression of TIMP-1 and TIMP-2 in surgical specimen pairs of hepatocellular carcinoma and nontumoral liver and the correlation between their expression and clinicopathological characteristics.

METHODS

The localization of both transcripts and protein of TIMP-1 and TIMP-2 was studied by using in situ hybridization and immunohistochemistry.

RESULTS

TIMP-1 and TIMP-2 mRNA transcripts were found in tumor cells, hepatocyte, sinusoidal cells, endothelial cells and stromal cells. Signal intensity of TIMP-1 was stronger than that of TIMP-2. The results of immunohistochemical stainings were concordant with those obtained by in situ hybridization. Expression of TIMP-1 and TIMP-2 was observed in tumorous tissue, in nontumorous tissue and in the portions of the tumors adjacent to the capsules. However, a clear difference in TIMP-1 and TIMP-2 mRNA expression was not observed among the three tissue types. The intensity of TIMP-2 expression was generally weaker than that of TIMP-1, and the intensity of TIMP-1 and TIMP-2 mRNA expression did not correlate with variable clinicopathological characteristics.

CONCLUSION

TIMPs was expressed in tumor cells and many cell types of the nontumoral liver. Further investigations for TIMPs' unknown functional role are needed.

Prognostic significance of E-cadherin/catenin complex expression in gastric cancer

Abnormal expression of E-cadherin/catenin complex in cancer has been associated with poor differentiation and acquisition of invasiveness, suggesting a possible role of this protein as an invasion suppressor. In this study, we conducted an immunohistochemical investigation of all components of the E-cadherin/catenin complex in 65 gastric cancer patients. Abnormal expression of E-cadherin and, alpha- and gamma-catenin occurred more frequently in diffuse than in intestinal type of gastric cancer, and correlated with poor differentiation. Abnormal expression of E-cadherin and beta-catenin correlated with poor survival. Abnormal expression of all four components of the complex was associated with poorly differentiated and diffuse-type carcinoma, and poor survival. In the multivariate analysis, abnormal expression of the E-cadherin/catenin complex was not an independent prognostic factor. These results suggest that the E-cadherin/catenin complex may be a useful marker of differentiation and prognosis in gastric cancer. Further studies are warranted to clarify the impact of the E-cadherin/catenin complex on prognostic factor of gastric cancer.

Inwardly rectifying K+ channels in the basolateral membrane of rat pancreatic acini

Previous studies of the whole-cell K+ conductance suggest the presence of inwardly rectifying K+ channels (Kir) in rat pancreatic acini (RPAs). Here we investigate the properties of Kir of RPAs using patch-clamp techniques. The whole-cell current-to-voltage relationship of freshly isolated RPAs was steeper for inward currents than for outward currents when the extracellular K+ concentration ([K+]o) was raised. With a high [K+]o (145 mM), external application of Ba2+ and Cs+ blocked the inward K+ current in a voltage-dependent manner. The apparent IC50 of Ba2+ was 8.5+/-1.9 microM and 1.1+/-0.2 microM at -70 mV and -130 mV, respectively (n=5). The IC50 of Cs+ was 3.5+1.1 mM and 0.2+0.1 mM at -60 mV and -120 mV, respectively (n=4). Application of Ba2+ (0.1 mM) to the extracellular solution reversibly depolarized RPAs from -43+1.1 mV to -37+/-1.2 mV (n=20). In the cell-attached configuration with 145 mM KC1 in the pipette solution, we observed inwardly rectifying channels with a high open probability (PO) of 0.85+/-0.02 (n=6) and a slope conductance (Gs) of 30+/-2.8 pS (n=13). The same type of channel was observed in the outside-out patch. We could also observe a very small conductance K+ channel which was resistant to 0.1 mM Ba2+ and did not show inward rectification (n=11). RT-PCR analysis of RPA confirmed the presence of transcripts for Kir2.1, Kir2.3 and Kir7.1 subfamilies as molecular candidates for the observed channels. The above results demonstrate the presence of Kir channels in the basolateral membrane of the RPA, which may be important for the K+ recycling process during electrolyte secretion as well as for maintaining a hyperpolarized membrane.

Insulin stimulates production of nitric oxide via ERK in osteoblast cells

We explored to determine if iNOS could be induced by insulin in osteoblast-like UMR-106 cells. Insulin (100 nM) stimulated nitric oxide production by twofold and significantly increased iNOS mRNA and protein levels. Insulin also increased collagen synthesis, but had little effect on alkaline phosphatase activity. In contrast, IGF-1 had little effect on NO production below 10 nM and it stimulated NO production by only 57% at 100 nM. IGF-1 had little effect on collagen levels, whereas it inhibited alkaline phosphatase activities in a dose-dependent manner. When an MEK inhibitor was preincubated, insulin failed to stimulate NO production, whereas insulin dramatically increased NO production in the ERK1 overexpressed cells. Taken together, it is proposed that insulin increases iNOS mRNA, iNOS protein, and NO production, possibly via activation of ERK. These may play an important role in osteoblast functions such as collagen synthesis.

Remission in models of type 1 diabetes by gene therapy using a single-chain insulin analogue

A cure for diabetes has long been sought using several different approaches, including islet transplantation, regeneration of beta cells and insulin gene therapy. However, permanent remission of type 1 diabetes has not yet been satisfactorily achieved. The development of type 1 diabetes results from the almost total destruction of insulin-producing pancreatic beta cells by autoimmune responses specific to beta cells. Standard insulin therapy may not maintain blood glucose concentrations within the relatively narrow range that occurs in the presence of normal pancreatic beta cells. We used a recombinant adeno-associated virus (rAAV) that expresses a single-chain insulin analogue (SIA), which possesses biologically active insulin activity without enzymatic conversion, under the control of hepatocyte-specific L-type pyruvate kinase (LPK) promoter, which regulates SIA expression in response to blood glucose levels. Here we show that SIA produced from the gene construct rAAV-LPK-SIA caused remission of diabetes in streptozotocin-induced diabetic rats and autoimmune diabetic mice for a prolonged time without any apparent side effects. This new SIA gene therapy may have potential therapeutic value for the cure of autoimmune diabetes in humans.