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.

Unbalanced atrioventricular septal defect with parachute valve

A 5-month-old male patient presented with right-dominant unbalanced atrioventricular septal defect and left-sided parachute valve, and underwent successful biventricular repair. Because of the presence of a small left ventricle, left atrium, and a single left papillary muscle, an additional orifice was created in the left-sided atrioventricular valve with artificial partitioning of the right-sided atrioventricular valve. There was no evidence of mitral stenosis or regurgitation on follow-up echocardiography.

ACE inhibitors attenuate expression of renal transforming growth factor-beta1 in humans

Progressive nephropathies are characterized by the enhanced accumulation of extracellular matrix in the kidney. Overproduction of transforming growth factor-beta (TGF-beta) was shown to result in pathological tissue fibrosis through the accumulation of extracellular matrix proteins. It has been proposed that angiotensin II stimulates TGF-beta production. Despite accumulating data supporting the effects of angiotensin-converting enzyme (ACE) inhibitors on the attenuation of TGF-beta in vitro and in rats, such studies in humans are lacking. The present study sought to determine the effects of ACE inhibitors on TGF-beta1 in patients with glomerulonephritis. Using competitive polymerase chain reaction and the sandwich enzyme-linked immunosorbent assay, TGF-beta1 messenger RNA (mRNA) abundance and TGF-beta1 protein levels were measured. Patients with immunoglobulin A nephropathy administered ACE inhibitors showed significantly lower renal TGF-beta1 gene expression than patients not administered these medications (mean ratios of TGF-beta1/beta-actin, 4.27 +/- 0.62 [SEM] versus 14.81 +/- 3.87; P < 0.05), whereas no difference was noted between patients administered ACE inhibitors and healthy controls (4.27 +/- 0.62 versus 2.78 +/- 0.71). ACE inhibitor therapy did not affect TGF-beta1 mRNA expression in freshly isolated mononuclear cells. Urine and serum TGF-beta1 protein levels were not affected by the administration of ACE inhibitors. However, possibly a longer duration of treatment would decrease TGF-beta1 levels in urine or blood. In conclusion, we observed a significant reduction in TGF-beta1 expression in the kidney by ACE inhibitors, and this suggests that the effects of ACE inhibitors observed in animals can be extrapolated to patients with chronic renal disease.

Identification of motifs for cell adhesion within the repeated domains of transforming growth factor-beta-induced gene, betaig-h3

betaig-h3 is a transforming growth factor-beta-inducible cell adhesion molecule that has four characteristic homologous repeated domains. We made recombinant betaig-h3 proteins, which were highly active in mediating human corneal epithelial (HCE) cell adhesion and spreading. The 2nd and the 4th repeated domains were sufficient to mediate HCE cell adhesion. A sequence analysis showed that aspartic acid (Asp) and isoleucine (Ile) of the 2nd and the 4th domains are highly conserved in many fasciclin 1 homologous (fas-1) domains. Substitution mutational study identified these two amino acids are essential for cell adhesion. Synthetic peptides containing Asp and Ile, NKDIL and EPDIM derived from the 2nd and the 4th domains, respectively, almost completely blocked cell adhesion mediated by not only wild type betaig-h3 but also each of the 2nd and the 4th domains. These peptides alone were fully active in mediating cell adhesion. In addition, we demonstrated the functional receptor for betaig-h3 is alpha(3)beta(1) integrin. These results, therefore, establish the essential motifs within the 2nd and the 4th domains of betaig-h3, which interact with alpha(3)beta(1) integrin to mediate HCE cell adhesion to betaig-h3 and suggest that other proteins containing Asp-Ile in their fas-1 domains could possibly function as cell adhesion molecules.

Blastocyst viability and generation of transgenic cattle following freezing of in vitro produced, DNA-injected embryos

This study examined whether the viability, determined in vitro, of DNA-injected bovine embryos produced in vitro was affected by freezing, and if the frozen embryos developed to term following transfer to recipients. In vitro fertilized zygotes were injected with the pBL1 gene and then co-cultured with mouse embryonic fibroblasts (MEF) in CR1aa medium. Embryos were prepared for cryopreservation by exposure to a 10% (v/v) glycerol solution, loaded into 0.25 ml straws and then frozen by conventional slow freezing. Thawing was by rapid warming in water (37 degrees C) and embryos were rehydrated in PBS diluents of 6%, 3% and 0% (v/v) glycerol supplemented with 0.25 M sucrose and 0.5% (w/v) BSA. In Experiment 1, blastocysts that developed from DNA-injected embryos were individually classified into three morphological groups and three stages of development prior to freezing. DNA-injected blastocysts of excellent quality at freezing showed a higher survival rate (78.8+/-10.6%) after thawing than those of good (60. 9+/-16.4%) or fair (12.5+/-5.9%) quality (P<0.05). Post-thaw survival rate, judged in vitro, increased with more advanced stage of blastocyst development at freezing (early 48.8+/-15.9%, mid 52. 1+/-12.6% and expanded 71.2+/-1.1; P<0.05). In Experiment 2, the frozen/thawed embryos were transferred to recipients to examine in vivo viability. Following transfer of one or two embryos per recipient, pregnancy rates at 60 days of gestation were 13.6% (13/96) for frozen embryos and 26.5% (43/162) for fresh embryos (P<0. 05). Of the 12 live calves born from the frozen/thawed embryos, two males (18.3%) were transgenic. None of the live-born calves derived from fresh embryos exhibited the transgene. One of transgenic bulls did not produce transgenic sperm. Three out of 23 calves (13.0%) produced from cows inseminated with semen of the other bull were transgenic, suggesting that this animal was a germ-line mosaic. These studies indicated that the viability of in vitro produced, DNA-injected bovine blastocysts was affected by freezing and by both the quality and stage of development of the embryo prior to freezing. The generation of transgenic cattle demonstrates that it is feasible to freeze DNA-injected, in vitro produced embryos.

Influence of the sequence variations of the HLA-DR promoters derived from human melanoma cell lines on nuclear protein binding and promoter activity

In previous studies we reported that the expression of HLA-DR on melanoma cell lines was differentially modulated by IFN- gamma and that the transcription rate was responsible for this differential modulation. We have also reported the nucleotide sequence variations in the promoter region of HLA-DR genes, and proposed that differences in the promoter activity by the sequence variations of the HLA-DR promoters might contribute to such a differential transcriptional regulation at the promoter level. In this study, in order to assess whether the sequence variations of the HLA-DR promoters affect the factor binding and exert influence on the promoter activity, nuclear factor binding to our previous six HLA-DRA and fourteen HLA-DRB promoter clones was evaluated with the nuclear protein extracted from a B-lymphoblastoid cell line (BLCL), BH, together with the chloramphenicol acetyltransferase (CAT) reporter assay. In the HLA-DRA promoters, clone #35 containing one bp nucleotide sequence variation at the octamer binding site (OCT) (GATTTGC to GATCTGC) showed relatively weak factor binding. In the HLA-DRB promoters, clusters I, III, and IV of our previous HLA-DRB promoter homologues, containing one bp nucleotide sequence variation (GATTCG) in their Y boxes exhibited weak factor binding and CAT activity compared to other clusters (GATTGG) that showed strong factor binding and CAT activity. This data suggests chat the binding patterns of transcription factors influenced by the nucleotide sequence variations of the HLA-DR promoter could affect the promoter activity and the DNA sequence elements in the HLA-DR promoter could mediate transcriptional regulation.

A case of epidermoid cyst of the intrapancreatic accessory spleen

A 54-year-old woman presented with a huge palpable mass on left upper quadrant of the abdomen. After preoperative work-up, a cystic disease of pancreatic tail or accessory spleen was initially suspected. We performed exploratory laparotomy and resected both the spleen and a 15 x 11 cm-sized huge cystic mass containing a part of solid component which extended continuously to the pancreatic tail. The solid component, comprising the upper portion of the resected cyst, was reddish brown and granular like as normal splenic tissue. The inner surface of the cyst was smooth and was filled with yellowish white material. Histologic examination showed an epidermoid cyst originating in the accessory spleen of the pancreatic tail lacking hair or skin appendages.

Neural spike sorting under nearly 0-dB signal-to-noise ratio using nonlinear energy operator and artificial neural-network classifier

We report a result on neural spike sorting under conditions where the signal-to-noise ratio is very low. The use of nonlinear energy operator enables the detection of an action potential, even when the SNR is so poor that a typical amplitude thresholding method cannot be applied. The superior detection ability facilitates the collection of a training set under lower SNR than that of the methods which employ simple amplitude thresholding. Thus, the statistical characteristics of the input vectors can be better represented in the neural-network classifier. The trained neural-network classifiers yield the correct classification ratio higher than 90% when the SNR is as low as 1.2 (0.8 dB) when applied to data obtained from extracellular recording from Aplysia abdominal ganglia using a semiconductor microelectrode array.

Loose bodies after arthroscopic osteochondral autograft in osteochondritis dissecans of the knee

We report a case of loose bodies from the donor site as a complication after the osteochondral autograft for the treatment of osteochondritis dissecans. Eight months after surgery, 3 osteochondral loose fragments, having dislodged from the donor sites of the osteochondral autograft, were found in the posteromedial portion, posterolateral portion, and anterior compartment of the knee, respectively. A large osteochondral defect can be treated successfully with arthroscopic autogenous bone graft. When filling the donor site with the recipient bone core, only the cancellous portion should be inserted into the donor socket.

Twenty-year trend of chronic excretors of tubercle bacilli based on the nationwide tuberculosis prevalence surveys in Korea, 1975-1995

SETTING

A study of chronic excretors of tubercle bacilli (chronic cases) based on the nationwide random sample surveys of tuberculosis prevalence conducted in Korea from 1975 through 1995.

OBJECTIVE

To investigate the temporal trend of the prevalence of chronic cases, and to match these with treatment outcomes and drug resistance rates.

DESIGN

Bacillary cases were classified by history of chemotherapy into new (those who denied a history of chemotherapy), non-chronic (those who had taken chemotherapy for less than 2 years) and chronic cases (those who had taken chemotherapy for more than 2 years).

RESULTS

Chronic cases decreased from 107 to 12 per 100000 population (annual rate of reduction [ARR] 11.89%) over the 20-year period. The ARR of chronic cases was significantly greater than that of new cases, and accelerated from 1985 (ARR 15.83%), after the application of short course chemotherapy. Rates of overall drug resistance rates increased up to 1980, and those of multidrug resistance up to 1985, followed by a decrease thereafter. A reduction in chronic cases was observed even during the period of increase in drug resistance (including multidrug resistance).

CONCLUSION

The prevalence of chronic tuberculosis cases has decreased due to improvements in overall treatment outcome.

Arthroscopic treatment for localized pigmented villonodular synovitis of the knee

This study investigated 11 patients with localized pigmented villonodular synovitis of the knee that was diagnosed and treated by arthroscopic technique. There were six male and five female patients between the ages of 15 and 59 years (mean, 34.6 years). Seven patients reported extension limitation without joint line tenderness. Four of the 11 patients had a history of trauma before the onset of knee symptoms. All patients were treated by arthroscopic resection with partial synovectomy. The most common involved site was the anteromedial synovium near the anterior horn of the medial meniscus (five patients). The remaining cases were located in the anterior fat pad (two patients), suprapatellar pouch, posteromedial compartment, medial gutter, and the anterior horn of the lateral meniscus. Nine patients had one mass, and the remaining patients each had two or three masses. There was no evidence of recurrence at followup for an average of 29.9 months (range, 24-48 months). Arthroscopy is effective in the diagnosis of localized pigmented villonodular synovitis with minimal morbidity, and complete arthroscopic excision can be considered the definitive treatment for localized pigmented villonodular synovitis.

Nocardiopsis kunsanensis sp. nov., a moderately halophilic actinomycete isolated from a saltern

A moderately halophilic actinomycete, designated HA-9T, was isolated from a saltern in Kunsan, Republic of Korea, and was the subject of polyphasic identification. Analysis of 16S rDNA indicated that the isolate belonged to the genus Nocardiopsis, but differed genetically from other Nocardiopsis species. Strain HA-9T contained meso-diaminopimelic acid, no diagnostic sugars, hexa- or octa-hydrogenated menaquinones with 10 isoprene units, straight-chain saturated or monounsaturated, iso-, anteiso-, 10-methyl branched fatty acids with 13-18 carbons and type III phospholipids. All of these characters consistently assign the isolate to the genus Nocardiopsis. All of the validly described Nocardiopsis species, including moderately halophilic Nocardiopsis halophila, can be differentiated from the saltern isolate using morphological and physiological traits. On the basis of polyphasic evidence, the name Nocardiopsis kunsanensis sp. nov. is proposed for strain HA-9T (= KCTC 9831T), which is designated the type strain.

Improvement of oxidative stability of conjugated linoleic acid (CLA) by microencapsulation in cyclodextrins

Oxidative stability of conjugated linoleic acid (CLA) encapsulated in alpha-, beta-, and gamma-cyclodextrins (designated CLA/CDs microencapsules) was studied by measuring the headspace-oxygen depletion in airtight serum bottles and by measuring the peroxide values (POV). The rate of oxygen depletion was reduced from 41.0 (control) to 21.5, 2.1, 1.2, and 1.1 micromol/L.h(-)(1) by CLA/alpha-CD microencapsules at 1:1, 1:2, 1:4, and 1:6 mole ratios, respectively, indicating that CLA oxidation was completely protected by a 1:4 mole ratio of CLA/alpha-CD. Such a protective effect by CLA/beta-CD or CLA/gamma-CD microencapsules was achieved at a 1:6 mole ratio, but the effect by CLA/beta-CD was slightly greater than that by CLA/gamma-CD. The protective effect of alpha-, beta-, and gamma-CDs for CLA oxidation was confirmed by their POV-reducing abilities in CLA/CDs. These results suggest that alpha-CD was the most effective for the protection of CLA oxidation by microencapsulation, followed by beta-CD and gamma-CD.

Recovery and potential utility of YACs as circular YACs/BACs

A method has been established to convert pYAC4-based linear yeast artificial chromosomes (YACs) into circular chromosomes that can also be propagated in Escherichia coli cells as bacterial artificial chromosomes (BACs). The circularization is based on use of a vector that contains a yeast dominant selectable marker (G418R), a BAC cassette and short targeting sequences adjacent to the edges of the insert in the pYAC4 vector. When it is introduced into yeast, the vector recombines with the YAC target sequences to form a circular molecule, retaining the insert but discarding most of the sequences of the YAC telomeric arms. YACs up to 670 kb can be efficiently circularized using this vector. Re-isolation of megabase-size YAC inserts as a set of overlapping circular YAC/BACs, based on the use of an Alu-containing targeting vector, is also described. We have shown that circular DNA molecules up to 250 kb can be efficiently and accurately transferred into E.coli cells by electroporation. Larger circular DNAs cannot be moved into bacterial cells, but can be purified away from linear yeast chromosomes. We propose that the described system for generation of circular YAC derivatives can facilitate sequencing as well as functional analysis of genomic regions.

Prevention of encephalomyocarditis virus-induced diabetes by live recombinant Mycobacterium bovis bacillus Calmette-Guérin in susceptible mice

The D variant of encephalomyocarditis (EMC-D) virus causes diabetes in susceptible mice by direct cytolysis of pancreatic beta-cells. cDNA covering the major outer capsid protein (VP1) of the EMC-D virus was cloned into Mycobacterium bovis bacillus Calmette-Guerin (BCG). None of the SJL/J mice immunized with live recombinant BCG-VP1 (rBCG-VP1) became diabetic when challenged with the highly diabetogenic EMC-D virus, but the control mice inoculated with normal BCG developed diabetes during the same challenge. VP1-specific antibodies (including neutralizing antibodies) were markedly increased over time and reached the maximum titer at week 10 after a single immunization. The plateau of the titer lasted longer than 4 weeks. Mice and guinea pigs immunized with live rBCG-VP1 showed strong delayed-type hypersensitivity to the VP1 of the EMC-D virus. The preventive immunity still worked effectively 10 months after the primary immunization. At that time, the VP1-specific antibody was almost undetectable in the bloodstream, but a large number of VP1-specific lymphocytes was found in the spleen of the immunized mice. Our results show that live rBCG-VP1 elicits effective humoral and long-lasting cellular immune responses against EMC-D virus infection that results in the prevention of virus-induced diabetes in susceptible mice.