Vildagliptin preserves the mass and function of pancreatic β cells via the developmental regulation and suppression of oxidative and endoplasmic reticulum stress in a mouse model of diabetes

AIM

We investigated the molecular mechanisms by which vildagliptin preserved pancreatic β cell mass and function.

METHODS

Morphological, biochemical and gene expression profiles of the pancreatic islets were investigated in male KK-A(y) -TaJcl(KK-A(y) ) and C57BL/6JJcl (B6) mice aged 8 weeks which received either vildagliptin or a vehicle for 4 weeks.

RESULTS

Body weight, food intake, fasting blood glucose, plasma insulin and active glucagon-like peptide-1 were unchanged with vildagliptin treatment in both mice. In KK-A(y) mice treated with vildagliptin, increased plasma triglyceride (TG) level and islet TG content were decreased, insulin sensitivity significantly improved, and the glucose tolerance ameliorated with increases in plasma insulin levels. Furthermore, vildagliptin increased glucose-stimulated insulin secretion, islet insulin content and pancreatic β cell mass in both strains. By vildagliptin, the expression of genes involved in cell differentiation/proliferation was upregulated in both strains, those related to apoptosis, endoplasmic reticulum stress and lipid synthesis was decreased and those related to anti-apoptosis and anti-oxidative stress was upregulated, in KK-A(y) mice. The morphological results were consistent with the gene expression profiles.

CONCLUSION

Vildagliptin increases β cell mass by not only directly affecting cell kinetics but also by indirectly reducing cell apoptosis, oxidative stress and endoplasmic reticulum stress in diabetic mice.

The human glucagon-like peptide-1 analogue liraglutide preserves pancreatic beta cells via regulation of cell kinetics and suppression of oxidative and endoplasmic reticulum stress in a mouse model of diabetes

AIMS/HYPOTHESIS

We investigated the molecular mechanism by which the human glucagon-like peptide-1 analogue liraglutide preserves pancreatic beta cells in diabetic db/db mice.

METHODS

Male db/db and m/m mice aged 10 weeks received liraglutide or vehicle for 2 days or 2 weeks. In addition to morphological and biochemical analysis of pancreatic islets, gene expression profiles in the islet core area were investigated by laser capture microdissection and real-time RT-PCR.

RESULTS

Liraglutide treatment for 2 weeks improved metabolic variables and insulin sensitivity in db/db mice. Liraglutide also increased glucose-stimulated insulin secretion (GSIS) and islet insulin content in both mouse strains and reduced triacylglycerol content in db/db mice. Expression of genes involved in cell differentiation and proliferation in both mouse strains was regulated by liraglutide, which, in db/db mice, downregulated genes involved in pro-apoptosis, endoplasmic reticulum (ER) stress and lipid synthesis, and upregulated genes related to anti-apoptosis and anti-oxidative stress. In the 2 day experiment, liraglutide slightly improved metabolic variables in db/db mice, but GSIS, insulin and triacylglycerol content were not affected. In db/db mice, liraglutide increased gene expression associated with cell differentiation, proliferation and anti-apoptosis, and suppressed gene expression involved in pro-apoptosis; it had no effect on genes related to oxidative stress or ER stress. Morphometric results for cell proliferation, cell apoptosis and oxidative stress in db/db mice islets were consistent with the results of the gene expression analysis.

CONCLUSIONS/INTERPRETATION

Liraglutide increases beta cell mass not only by directly regulating cell kinetics, but also by suppressing oxidative and ER stress, secondary to amelioration of glucolipotoxicity.

Cranio-lenticulo-sutural dysplasia associated with defects in collagen secretion

Cranio-lenticulo-sutural dysplasia (CLSD) is a rare autosomal recessive syndrome manifesting with large and late-closing fontanels and calvarial hypomineralization, Y-shaped cataracts, skeletal defects, and hypertelorism and other facial dysmorphisms. The CLSD locus was mapped to chromosome 14q13-q21 and a homozygous SEC23A F382L missense mutation was identified in the original family. Skin fibroblasts from these patients exhibit features of a secretion defect with marked distension of the endoplasmic reticulum (ER), consistent with SEC23A function in protein export from the ER. We report an unrelated family where a male proband presented with clinical features of CLSD. A heterozygous missense M702V mutation in a highly conserved residue of SEC23A was inherited from the clinically unaffected father, but no maternal SEC23A mutation was identified. Cultured skin fibroblasts from this new patient showed a severe secretion defect of collagen and enlarged ER, confirming aberrant protein export from the ER. Milder collagen secretion defects and ER distention were present in paternal fibroblasts, indicating that an additional mutation(s) is present in the proband. Our data suggest that defective ER export is the cause of CLSD and genetic element(s) besides SEC23A may influence its presentation.

Roles of tandem-pore K+ channels in plants - a puzzle still to be solved

The group of voltage-independent K(+) channels in Arabidopsis thaliana consists of six members, five tandem-pore channels (TPK1-TPK5) and a single K(ir)-like channel (KCO3). All TPK/KCO channels are located at the vacuolar membrane except for TPK4, which was shown to be a plasma membrane channel in pollen. The vacuolar channels interact with 14-3-3 proteins (also called General Regulating Factors, GRFs), indicating regulation at the level of protein-protein interactions. Here we review current knowledge about these ion channels and their genes, and highlight open questions that need to be urgently addressed in future studies to fully appreciate the physiological functions of these ion channels.

Assessment of early treatment response after CT-guided radiofrequency ablation of unresectable lung tumours by diffusion-weighted MRI: a pilot study

The aim of this study was to evaluate prospectively the early treatment response after CT-guided radiofrequency ablation (RFA) of unresectable lung tumours by MRI including diffusion-weighted imaging (DWI). The study protocol was approved by the ethics committee of our hospital and signed consent was obtained from each patient. We studied 17 patients with 20 lung lesions (13 men and 4 women; mean age, 69+/-9.8 years; mean tumour size, 20.8+/-9.0 mm) who underwent RFA using a LeVeen electrode between November 2006 and January 2008. MRI was performed on a 1.5T unit before and 3 days after ablation. We compared changes in the apparent diffusion coefficient (ADC) on DWI and response evaluation based on subsequent follow-up CT. 14 of the 20 treatment sessions showed no local progression on follow-up CT, whereas 6 treatment sessions showed local progression (range, 3-17 months; mean, 6 months). For the no-progression group, the ADC pre- and post-RFA were 1.15+/-0.31 x 10(-3) mm(2) s(-1) and 1.49+/-0.24 x 10(-3) mm(2) s(-1), respectively, while the respective ADC values for those that showed local progression were 1.05+/-0.27 x 10(-3) mm(2) s(-1) and 1.24+/-0.20 x 10(-3) mm(2) s(-1). The ADC of the ablated lesion was significantly higher than before the procedure (p<0.05). There was a significant difference in the ADC post-RFA between no-progression and local progression groups (p<0.05). Our prospective pilot study showed that the ADC without local progression was significantly higher than with local progression after RFA, suggesting that the ADC can predict the response to RFA for lung tumours.

Clinical relevance of precore and basal core promoter variants of hepatitis B virus during natural hepatitis B e antigen seroconversion may be overstated

BACKGROUND

Clinical relevance of nucleotide changes in precore and basal core promoters in the hepatitis B virus genome during hepatitis B e antigen seroconversion may be overstated. The authors investigated the existence and changes in the relative proportion of variants to wild virus that occur with seroconversion.

METHODS

Sera from 30 school-aged long-term hepatitis B virus carriers, including 11 tested before and after seroconversion during 1 to 8 years of follow-up, were evaluated for variations in nucleotide sequences of the basal core promoter (T1762 and A1764), precore region (A1869), and carboxyl-terminus of the X region of the hepatitis B virus genome using an amplification refractory mutation detection system with mutant-specific primers.

RESULTS

All variants were found to already exist before seroconversion at various wild-type/mutant ratios. The positive rates of these variants were not changed with loss of hepatitis B e antigen. Although there was a relative increase in the concentration of these mutants in wild-type/mutant mixed populations, most patients with only a wild-type population maintained the same pattern after loss of hepatitis B e antigen.

CONCLUSIONS

Our results indicate that hepatitis B virus exists as a quasi species, and correlations of nucleotide sequences with clinical and serologic findings must be done with caution.

[The new experimental ulcerative colitis model in rats induced by subserosal injection of acetic acid]

We have developed a new experimental ulcerative colitis model in rats. Topical pathological change of a round or a ellips shape was induced by subserosal injection of acetic acid (20%, 0.02 ml) into the middle colon of rats. The size of the induced ulcer could directly be measured using a caliper gauge, and the result was expressed as the ulcer area (mm2). We determined the concentration of leukotriene B4 (LTB4), which is one of important clinical factors, in the ulcer region and found that the quantity of LTB4 was well correlated with the size of the ulcer area. Histopathological studies of the ulcer region demonstrated that there were some morphological similarities to the human form of ulcerative colitis, characterized by edema, necrosis, inflammatory cell infiltration, crypt abscess and granulation tissue formation. Effects of 5-aminosalicylic acid and sodium prednisolone phosphate were investigated by intrarectal administration in this colitis model. The predominant improvement of colitis was obtained from both treatments in the ranges of the clinical doses of each drug. In conclusion, we suggest that this colitis model provides a new way for quantitative evaluation of the efficacy of new therapeutic agents for ulcerative colitis.

Dynamics of the COPII coat with GTP and stable analogues

We have developed an assay to monitor the assembly of the COPII coat onto liposomes in real time. We show that with Sar1pGTP bound to liposomes, a single round of assembly and disassembly of the COPII coat lasts a few seconds. The two large COPII complexes Sec23/24p and Sec13/31p bind almost instantaneously (in less than 1 s) to Sar1pGTP-doped liposomes. This binding is followed by a fast (less than 10 s) disassembly due to a 10-fold acceleration of the GTPase-activating protein activity of Sec23/24p by the Sec13/31p complex. Experiments with the phosphate analogue BeFx suggest that Sec23/24p provides residues directly involved in GTP hydrolysis on Sar1p.

Peroxisome proliferator-activated receptor gamma ligand-induced growth inhibition of human hepatocellular carcinoma

Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands have been implicated in the growth inhibition and differentiation of certain human cancers with diverse tissue origin. In this study, expression of PPARgamma in human hepatocellular carcinoma (HCC) and the effect of PPARgamma ligands on HCC cells were investigated in vitro using Hep G2, HuH-7, KYN-1 and KYN-2 cell lines. All cell lines were found to express functionally active PPARgamma and a marked growth inhibition was induced by thiazolidinedione ligands troglitazone, and pioglitazone as well as with its natural ligand 15-deoxy-Delta(12,14)-prostaglandin J(2). The growth inhibitory effect was associated with a dose-dependent inhibition of DNA synthesis, cell cycle progression and alpha fetoprotein expression.

The ADP ribosylation factor-nucleotide exchange factors Gea1p and Gea2p have overlapping, but not redundant functions in retrograde transport from the Golgi to the endoplasmic reticulum

The activation of the small ras-like GTPase Arf1p requires the action of guanine nucleotide exchange factors. Four Arf1p guanine nucleotide exchange factors have been identified in yeast: Sec7p, Syt1p, Gea1p, and its homologue Gea2p. We identified GEA2 as a multicopy suppressor of a sec21-3 temperature-sensitive mutant. SEC21 encodes the gamma-subunit of coatomer, a heptameric protein complex that together with Arf1p forms the COPI coat. GEA1 and GEA2 have at least partially overlapping functions, because deletion of either gene results in no obvious phenotype, whereas the double null mutant is inviable. Conditional mutants defective in both GEA1 and GEA2 accumulate endoplasmic reticulum and Golgi membranes under restrictive conditions. The two genes do not serve completely overlapping functions because a Deltagea1 Deltaarf1 mutant is not more sickly than a Deltaarf1 strain, whereas Deltagea2 Deltaarf1 is inviable. Biochemical experiments revealed similar distributions and activities for the two proteins. Gea1p and Gea2p exist both in membrane-bound and in soluble forms. The membrane-bound forms, at least one of which, Gea2p, can be visualized on Golgi structures, are both required for vesicle budding and protein transport from the Golgi to the endoplasmic reticulum. In contrast, Sec7p, which is required for protein transport within the Golgi, is not required for retrograde protein trafficking.

Co-infection by serologically-silent hepatitis B virus may contribute to poor interferon response in patients with chronic hepatitis C by down-regulation of type-I interferon receptor gene expression in the liver

Intrahepatic mRNA levels of type-I interferon (IFN) receptor genes have been shown to correlate with the clinical efficacy of IFN therapy in patients with chronic hepatitis C. Recently, co-infection by serologically-silent hepatitis B virus (HBV) has been assumed to be associated with the poor IFN response in patients with chronic hepatitis C. The aim of this study was to investigate the relationship between the co-infection of serologically-silent HBV and type-I IFN receptor gene expression in the liver of patients with chronic hepatitis C. The intrahepatic mRNA levels of IFNAR2, one of the two subunits of the type-I IFN receptor, were quantified and compared with both the prevalence of HBV DNA and the hepatitis C virus (HCV) genotype in 45 patients with chronic hepatitis C, who were negative for hepatitis B surface antigen. Co-infection, as evaluated by a nested polymerase chain reaction, was present in 22 patients (48.9%), with dominance of the HCV genotype 1b (65.2%) over genotype 2a (31.8%). Co-infection was associated with lower IFNAR2 mRNA levels, higher levels of serum HCV RNA, and a poor IFN response, regardless of the HCV genotype. The findings suggest the possibility that co-infection by serologically-silent HBV is one of the factors that can lead to an unfavorable IFN response in chronic hepatitis C by down-regulation of IFN receptor gene expression in the liver.

Co-infection by serologically-silent hepatitis B virus may contribute to poor interferon response in patients with chronic hepatitis C by down-regulation of type-I interferon receptor gene expression in the liver

Intrahepatic mRNA levels of type-I interferon (IFN) receptor genes have been shown to correlate with the clinical efficacy of IFN therapy in patients with chronic hepatitis C. Recently, co-infection by serologically-silent hepatitis B virus (HBV) has been assumed to be associated with the poor IFN response in patients with chronic hepatitis C. The aim of this study was to investigate the relationship between the co-infection of serologically-silent HBV and type-I IFN receptor gene expression in the liver of patients with chronic hepatitis C. The intrahepatic mRNA levels of IFNAR2, one of the two subunits of the type-I IFN receptor, were quantified and compared with both the prevalence of HBV DNA and the hepatitis C virus (HCV) genotype in 45 patients with chronic hepatitis C, who were negative for hepatitis B surface antigen. Co-infection, as evaluated by a nested polymerase chain reaction, was present in 22 patients (48.9%), with dominance of the HCV genotype 1b (65.2%) over genotype 2a (31.8%). Co-infection was associated with lower IFNAR2 mRNA levels, higher levels of serum HCV RNA, and a poor IFN response, regardless of the HCV genotype. The findings suggest the possibility that co-infection by serologically-silent HBV is one of the factors that can lead to an unfavorable IFN response in chronic hepatitis C by down-regulation of IFN receptor gene expression in the liver.

The p24 proteins are not essential for vesicular transport in Saccharomyces cerevisiae

To investigate the factors involved in the sorting of cargo proteins into COPII endoplasmic reticulum (ER) to Golgi apparatus transport vesicles, we have created a strain of S. cerevisiae (p24Delta8) that lacks all eight members of the p24 family of transmembrane proteins (Emp24p, Erv25p, and Erp1p to Erp6p). The p24 proteins have been implicated in COPI and COPII vesicle formation, cargo protein sorting, and regulation of vesicular transport in eukaryotic cells. We find that p24Delta8 cells grow identically to wild type and show delays of invertase and Gas1p ER-to-Golgi transport identical to those seen in a single Deltaemp24 deletion strain. Thus, p24 proteins do not have an essential function in the secretory pathway. Instead, they may serve as quality control factors to restrict the entry of proteins into COPII vesicles.

Multiple small lesions of hepatocellular carcinoma controlled by percutaneous and laparoscopic ethanol injection--a case report

A 61-year-old man was admitted to our clinic for a liver examination. Ultrasonography revealed multiple echo-rich lesions in both lobes. A laparoscopy showed a liver with an irregular surface, and a 3-mm-sized dark reddish lesion on the inferior surface of the right lobe. alpha-Fetoprotein and plasma protein induced by vitamin K absence or antagonist were normal. A liver biopsy specimen obtained from the small lesion by laparoscopy-guide showed a well-differentiated hepatocellular carcinoma with bile formation. Biopsy specimens obtained later from the 2 echo-rich lesions by ultrasonographic-guide were histologically similar to the lesion laparoscopically observed. Laparoscopic ethanol injection and percutaneous ethanol injection were performed as therapeutic procedures. Recurrence of hepatocellular carcinoma at the treated sites was not observed during the 6-year observation period. Thus, laparoscopy might play an important role in the early detection and treatment of hepatocellular carcinomas on the surface of the liver.

Sec24p and Iss1p function interchangeably in transport vesicle formation from the endoplasmic reticulum in Saccharomyces cerevisiae

The Sec23p/Sec24p complex functions as a component of the COPII coat in vesicle transport from the endoplasmic reticulum. Here we characterize Saccharomyces cerevisiae SEC24, which encodes a protein of 926 amino acids (YIL109C), and a close homologue, ISS1 (YNL049C), which is 55% identical to SEC24. SEC24 is essential for vesicular transport in vivo because depletion of Sec24p is lethal, causing exaggeration of the endoplasmic reticulum and a block in the maturation of carboxypeptidase Y. Overproduction of Sec24p suppressed the temperature sensitivity of sec23-2, and overproduction of both Sec24p and Sec23p suppressed the temperature sensitivity of sec16-2. SEC24 gene disruption could be complemented by overexpression of ISS1, indicating functional redundancy between the two homologous proteins. Deletion of ISS1 had no significant effect on growth or secretion; however, iss1Delta mutants were found to be synthetically lethal with mutations in the v-SNARE genes SEC22 and BET1. Moreover, overexpression of ISS1 could suppress mutations in SEC22. These genetic interactions suggest that Iss1p may be specialized for the packaging or the function of COPII v-SNAREs. Iss1p tagged with His(6) at its C terminus copurified with Sec23p. Pure Sec23p/Iss1p could replace Sec23p/Sec24p in the packaging of a soluble cargo molecule (alpha-factor) and v-SNAREs (Sec22p and Bet1p) into COPII vesicles. Abundant proteins in the purified vesicles produced with Sec23p/Iss1p were indistinguishable from those in the regular COPII vesicles produced with Sec23p/Sec24p.

Role of hepatitis B virus in non-B, non-C chronic liver disease: in vitro proliferation and interferon-gamma production of peripheral blood mononuclear cells in response to hepatitis B core antigen and its relation to hepatitis activity

OBJECTIVE

Although hepatitis B virus (HBV) DNA has been detected in the sera of patients with chronic liver disease with neither hepatitis B surface antigen nor antihepatitis C virus antibody (non-B, non-C [NBNC] CLD), whether HBV has some pathogenic role in NBNC CLD has not been made clear.

METHODS

To investigate the significance of HBV DNA in NBNC CLD, we performed in vitro stimulation assays of peripheral blood mononuclear cells (PBMCs) in response to hepatitis B core antigen (HBcAg) in 17 NBNC CLD patients.

RESULTS

HBV DNA with an 8-nucleotide deletion in the core promoter region was detected in 13 (76%) of the 17 patients by nested polymerase chain reaction. Interferon-gamma (IFN-gamma) production and proliferation of PBMCs of HBV DNA-positive patients showed a significant increase in response to HBcAg. The histological activity of hepatitis was also found to be significantly associated with the magnitude of IFN-gamma production and proliferation of PBMCs in response to HBcAg. Although five (38%) of the 13 HBV DNA-positive NBNC CLD patients had anti-HBs and/or anti-HBc, there was no difference in response of PBMCs to HBcAg between the HBV DNA-positive and -negative groups.

CONCLUSION

Our observation suggests that HBV may have a pathogenic role in HBV DNA-positive NBNC CLD, even in those patients without any serological markers of HBV.

Laparoscopic observations of hepatic capsular abnormalities: non-postoperative adhesions and hepatic capsular thickening

BACKGROUND

Hepatic capsular abnormalities (adhesions or thickening) are often striking at laparoscopy. However, their diagnosis is difficult because capsular abnormalities can also be caused by several pathologic conditions. The aim of this study was to systematically investigate the associated factors and prevalence of laparoscopically observed non-postoperative adhesions and hepatic capsular thickening.

METHODS

We reviewed all data and studied laparoscopically observed hepatic capsular abnormalities (non-postoperative adhesions and thickening) in 2500 consecutive patients who underwent laparoscopy from 1981 to 1997.

RESULTS

Non-postoperative adhesions were observed in 14.6% of cases and their frequency increased with age. Although several types of adhesions, from band-like to membrane-like, were seen, there were no correlations between type and underlying pathologic conditions, except tuberculous peritonitis with membrane-like adhesions and Fitz-Hugh-Curtis syndrome with violin string-like adhesions. Hepatic capsular thickening was observed in 9.7% of cases. The main associated factor was viral hepatitis followed by other liver diseases.

CONCLUSIONS

Hepatic capsular abnormalities are observed relatively frequently (21.5%) during laparoscopy. Initial laparoscopic diagnosis of non-postoperative adhesions may help in selecting patients with tuberculous peritonitis and Fitz-Hugh-Curtis syndrome for appropriate treatment.

Serologically silent hepatitis B virus coinfection in patients with hepatitis C virus-associated chronic liver disease: clinical and virological significance

Frequent coinfection of surface antigen-negative hepatitis B virus (silent HBV) in hepatitis C virus (HCV)-associated chronic liver disease (CLD) has been reported. The clinical and virological significance of silent HBV infection was investigated in 65 patients with HCV-associated CLD who subsequently received interferon (IFN) therapy. HBV DNA was detected in 34 (52.3%) patients by a nested polymerase chain reaction (PCR). Virologically, all of the 34 patients were found to have HBV with an eight-nucleotide deletion in the core promoter. Coinfection of silent HBV was more frequent with HCV genotype 1b than in 2a (64.3% vs. 28.6%, P<.01). With HCV genotype 1b, the serum RNA level was significantly higher (> or =10(6) copies per milliliter vs. < or =10(5) copies per milliliter) in patients with silent HBV than those without coinfection (P<.01). Clinically, silent HBV was associated with a higher level of serum alanine aminotransferase (158.5+/-104.8 vs. 121.8+/-78.6 IU/I; mean +/- SD) and a greater histological activity of hepatitis as evaluated by histological activity index score (9.4+/-3.8 vs. 8.6+/-4.5; mean +/- SD), although it was not statistically significant. Silent HBV was also associated with poor efficacy of IFN therapy (P<.01). The results suggest that silent HBV has some promoting effect for HCV replication, at least for HCV genotype 1b, and may affect the histological activity of hepatitis and IFN response in HCV-associated CLD.

Serologically silent hepatitis B virus coinfection in patients with hepatitis C virus-associated chronic liver disease: clinical and virological significance

Frequent coinfection of surface antigen-negative hepatitis B virus (silent HBV) in hepatitis C virus (HCV)-associated chronic liver disease (CLD) has been reported. The clinical and virological significance of silent HBV infection was investigated in 65 patients with HCV-associated CLD who subsequently received interferon (IFN) therapy. HBV DNA was detected in 34 (52.3%) patients by a nested polymerase chain reaction (PCR). Virologically, all of the 34 patients were found to have HBV with an eight-nucleotide deletion in the core promoter. Coinfection of silent HBV was more frequent with HCV genotype 1b than in 2a (64.3% vs. 28.6%, P<.01). With HCV genotype 1b, the serum RNA level was significantly higher (> or =10(6) copies per milliliter vs. < or =10(5) copies per milliliter) in patients with silent HBV than those without coinfection (P<.01). Clinically, silent HBV was associated with a higher level of serum alanine aminotransferase (158.5+/-104.8 vs. 121.8+/-78.6 IU/I; mean +/- SD) and a greater histological activity of hepatitis as evaluated by histological activity index score (9.4+/-3.8 vs. 8.6+/-4.5; mean +/- SD), although it was not statistically significant. Silent HBV was also associated with poor efficacy of IFN therapy (P<.01). The results suggest that silent HBV has some promoting effect for HCV replication, at least for HCV genotype 1b, and may affect the histological activity of hepatitis and IFN response in HCV-associated CLD.

Serologically silent hepatitis B virus coinfection in patients with hepatitis C virus-associated chronic liver disease: clinical and virological significance

Frequent coinfection of surface antigen-negative hepatitis B virus (silent HBV) in hepatitis C virus (HCV)-associated chronic liver disease (CLD) has been reported. The clinical and virological significance of silent HBV infection was investigated in 65 patients with HCV-associated CLD who subsequently received interferon (IFN) therapy. HBV DNA was detected in 34 (52.3%) patients by a nested polymerase chain reaction (PCR). Virologically, all of the 34 patients were found to have HBV with an eight-nucleotide deletion in the core promoter. Coinfection of silent HBV was more frequent with HCV genotype 1b than in 2a (64.3% vs. 28.6%, P<.01). With HCV genotype 1b, the serum RNA level was significantly higher (> or =10(6) copies per milliliter vs. < or =10(5) copies per milliliter) in patients with silent HBV than those without coinfection (P<.01). Clinically, silent HBV was associated with a higher level of serum alanine aminotransferase (158.5+/-104.8 vs. 121.8+/-78.6 IU/I; mean +/- SD) and a greater histological activity of hepatitis as evaluated by histological activity index score (9.4+/-3.8 vs. 8.6+/-4.5; mean +/- SD), although it was not statistically significant. Silent HBV was also associated with poor efficacy of IFN therapy (P<.01). The results suggest that silent HBV has some promoting effect for HCV replication, at least for HCV genotype 1b, and may affect the histological activity of hepatitis and IFN response in HCV-associated CLD.

Laparoscopic fenestration in combination with ethanol sclerotherapy prevents a recurrence of symptomatic giant liver cyst

Laparoscopic fenestration in combination with ethanol sclerotherapy of the cyst wall was performed in four patients with symptomatic giant solitary liver cyst. Two of these patients had recurrent liver cysts, which were resistant to simple laparoscopic fenestration. After the combination therapy, none of the cysts recurred during follow-up periods ranging from 11 to 33 months.

Coatomer, Arf1p, and nucleotide are required to bud coat protein complex I-coated vesicles from large synthetic liposomes

Synthetic coat protein complex I (COPI)-coated vesicles form spontaneously from large ( approximately 300 nm in diameter), chemically defined liposomes incubated with coatomer, Arf1p, and guanosine 5'-[gamma-thio]triphosphate. Coated vesicles are 40-70 nm in diameter, approximately the size of COPI vesicles formed from native membranes. The formation of COPI-coated buds and vesicles and the binding of Arf1p to donor liposomes depends on guanosine 5'-[gamma-thio]triphosphate. In contrast to the behavior of the COPII coat, coatomer binds to liposomes containing a variety of charged or neutral phospholipids. However, the formation of COPI buds and vesicles is stimulated by acidic phospholipids. In the absence of Arf1p, coatomer binds to liposomes containing dioleoylphosphatidic acid as a sole acidic phospholipid to form large coated surfaces without forming COPI-coated buds or vesicles. We conclude that Arf1p-GTP and coatomer comprise the minimum apparatus necessary to create a COPI-coated vesicle.

Chs6p-dependent anterograde transport of Chs3p from the chitosome to the plasma membrane in Saccharomyces cerevisiae

Chitin synthase III (CSIII), an enzyme required to form a chitin ring in the nascent division septum of Saccharomyces cerevisiae, may be transported to the cell surface in a regulated manner. Chs3p, the catalytic subunit of CSIII, requires the product of CHS6 to be transported to or activated at the cell surface. We find that chs6Delta strains have morphological abnormalities similar to those of chs3 mutants. Subcellular fractionation and indirect immunofluorescence indicate that Chs3p distribution is altered in chs6 mutant cells. Order-of-function experiments using end4-1 (endocytosis-defective) and chs6 mutants indicate that Chs6p is required for anterograde transport of Chs3p from an internal endosome-like membrane compartment, the chitosome, to the plasma membrane. As a result, chs6 strains accumulate Chs3p in chitosomes. Chs1p, a distinct chitin synthase that acts during or after cell separation, is transported normally in chs6 mutants, suggesting that Chs1p and Chs3p are independently packaged during protein transport through the late secretory pathway.

COPII-coated vesicle formation reconstituted with purified coat proteins and chemically defined liposomes

COPII vesicle formation requires only three coat assembly subunits: Sar1p, Sec13/31p, and Sec23/24p. PI 4-phosphate or PI 4,5-bisphosphate is required for the binding of these proteins to liposomes. The GTP-bound form of Sar1p recruits Sec23/24p to the liposomes as well as to the ER membranes, and this Sar1p-Sec23/24p complex is required for the binding of Sec13/31p. Ultrastructural analysis shows that the binding of COPII coat proteins to liposomes results in coated patches, coated buds, and coated vesicles of 50-90 nm in diameter. Budding proceeds without rupture of the donor liposome or vesicle product. These observations suggest that the assembly of the COPII coat on the ER occurs by a sequential binding of coat proteins to specific lipids and that this assembly promotes the budding of COPII-coated vesicles.

Interpretation of scintigraphy of papillary cystadenoma lymphomatosum (Warthin's tumor) on the basis of histopathologic findings

OBJECTIVES

The accumulation of 99mTc-pertechnetate in Warthin's tumor was estimated scintigraphically and histopathologically to determine the role of the epithelial component in scintigraphy.

STUDY DESIGN

Six cases underwent histopathologic examination and scintigraphic evaluation with 99mTc-pertechnetate. Histopathologically the tumors were classified into types according to the epithelial component and cystic space and compared with scintigraphic results evaluated by dynamic radioactive index and wash-out image.

RESULTS

Histopathologic and scintigraphic observations showed an adequate correlation. Cases with a large epithelial component and poor cystic space showed a large radioactive index of dynamic scintigraphy and hot accumulation of wash-out image.

CONCLUSION

The scintigraphic results were chiefly due to the epithelial component, but the influence of the cystic space could not be disregarded.

Dynamic MR imaging of the temporomandibular joint in patients with arthrosis: relationship between contrast enhancement of the posterior disk attachment and joint pain

OBJECTIVE

The purpose of this study was to determine the relationship between joint pain, disk position, and the degree of contrast enhancement of the posterior disk attachment in patients with temporomandibular joint arthrosis using dynamic contrast-enhanced MR imaging.

SUBJECTS AND METHODS

T1- and T2-weighted spin-echo and spoiled gradient-recalled acquisition in the steady state MR imaging was performed in 36 healthy volunteers and 105 patients who were asymptomatic or who had joint pain, muscular pain, or both. On T1-weighted images, the position of the disk was classified as normal and anteriorly displaced. Next, on sagittal spoiled gradient-recalled acquisition in the steady state MR images, signal intensity from teh posterior disk attachment was measured. Time-intensity curves of the signal-intensity ratio versus the time after contrast administration were obtained in each case. Diagnostic accuracy of enhancement among the clinical symptoms was assessed using receiver operating characteristic curves. Imaging findings of contrast enhancement were correlated with pain and disk position.

RESULTS

In quantitative measurement, a rapid enhancement pattern was seen most frequently in patients with joint-pain, whereas relatively gradual enhancement was seen in the healthy subjects and in patients who were asymptomatic or who had muscular pain. The mean peak-signal-intensity ratio of the group with joint pain was significantly higher than that of the other groups (p < .001). In the group with joint pain, anterior disk displacement without reduction was strongly associated with the mean signal-intensity ratio (p < .01). With regard to receiver operating characteristic analysis, the group with joint pain showed significantly greater accuracy than did the other groups (p < .001).

CONCLUSION

Our results suggest that prominent contrast enhancement of the posterior disk attachment on spoiled gradient-recalled acquisition in the steady state MR images may help differentiate intraarticular from extraarticular causes of pain in and around the temporomandibular joint. In the group with joint pain, anterior disk displacement without reduction was closely associated with prominent enhancement.

Selective uptake of cytosolic, peroxisomal, and plasma membrane proteins into the yeast lysosome for degradation

When glucose-starved cells are replenished with glucose, the key gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase), is selectively targeted from the cytosol to the yeast lysosome (vacuole) for degradation. The glucose-induced targeting of FBPase to the vacuole for degradation occurs in cells grown under a variety of metabolic conditions. Immunoelectron microscopic studies demonstrate that the uptake of FBPase by the vacuole is mediated in part by an autophagic process. FBPase can be found on the vacuolar membrane and also at the sites of membrane invaginations. Furthermore, FBPase is associated with different forms of vesicles, which are induced to accumulate inside the vacuole. We have identified peroxisomes as the organelles that are delivered to the vacuole for degradation when cells are replenished with glucose. Ultrastructural studies indicate that peroxisomes are engulfed by the vacuole by an autophagic process, leading to the destruction of whole organelles in the vacuole. Furthermore, the galactose transporter (Gal2p) is also delivered from the plasma membrane to the vacuole for degradation in response to glucose. Gal2p is delivered to the vacuole through the endocytic pathway, as mutants defective in receptor-mediated endocytosis fail to degrade Gal2p in response to glucose.

Biochemical requirements for the targeting and fusion of ER-derived transport vesicles with purified yeast Golgi membranes

In order for secretion to progress, ER-derived transport vesicles must target to, and fuse with the cis-Golgi compartment. These processes have been reconstituted using highly enriched membrane fractions and partially purified soluble components. The functionally active yeast Golgi membranes that have been purified are highly enriched in the cis-Golgi marker enzymes alpha 1,6 mannosyltransferase and GDPase. Fusion of transport vesicles with these membranes requires both GTP and ATP hydrolysis, and depends on cytosolic and peripheral membrane proteins. At least two protein fractions from yeast cytosol are required for the reconstitution of ER-derived vesicle fusion. Soluble fractions prepared from temperature-sensitive mutants revealed requirements for the Ypt1p, Sec19p, Sly1p, Sec7p, and Uso1 proteins. A model for the sequential involvement of these components in the targeting and fusion reaction is proposed.

New mutants of Saccharomyces cerevisiae affected in the transport of proteins from the endoplasmic reticulum to the Golgi complex

We have isolated new temperature-sensitive mutations in five complementation groups, sec31-sec35, that are defective in the transport of proteins from the endoplasmic reticulum (ER) to the Golgi complex. The sec31-sec35 mutants and additional alleles of previously identified sec and vacuolar protein sorting (vps) genes were isolated in a screen based on the detection of alpha-factor precursor in yeast colonies replicated to and lysed on nitrocellulose filters. Secretory protein precursors accumulated in sec31-sec35 mutants at the nonpermissive temperature were core-glycosylated but lacked outer chain carbohydrate, indicating that transport was blocked after translocation into the ER but before arrival in the Golgi complex. Electron microscopy revealed that the newly identified sec mutants accumulated vesicles and membrane structures reminiscent of secretory pathway organelles. Complementation analysis revealed that sec32-1 is an allele of BOS1, a gene implicated in vesicle targeting to the Golgi complex, and sec33-1 is an allele of RET1, a gene that encodes the alpha subunit of coatomer.

Plasma concentrations and tissue residues of bicozamycin given orally to pigs

Bicozamycin was dissolved in water and administered to pigs by stomach tube at 40 mg/kg once daily for 7 consecutive days. The plasma concentration was determined on days 1 and 7 of the dosing period. The mean (+/- SD) peak plasma concentrations were 2.06 +/- 0.36 micrograms/ml at 3.08 +/- 0.80 h on day 1 and 2.36 +/- 1.32 micrograms/ml at 2.80 +/- 0.74 h on day 7, the elimination half-lives being 3.80 +/- 0.92 h and 2.43 +/- 1.41 h, respectively. The mean areas under the plasma concentration-time curves were 15.88 +/- 2.18 (micrograms h)/ml on day 1 and 12.31 +/- 6.98 (micrograms h)/ml on day 7. These pharmacokinetic parameters did not differ between days 1 and 7, suggesting that there was no accumulation in the plasma after consecutive oral dosing. The residues in kidney, liver and muscle were examined in pigs slaughtered on days 1, 3 and 5 after the last dosing. One day after withdrawal, residues were found in the kidneys of all three pigs examined, at a mean concentration of 0.26 microgram/g, and in muscle from one pig, but not in liver from any of the pigs. Bicozamycin was not detected in any of the samples taken 3 or 5 days after withdrawal.

Enzyme immunoassay of sulfamethoxazole in chicken tissues: interlaboratory study

Three laboratories participated in the interlaboratory study of an enzyme immunoassay (EIA) method for determination of sulfamethoxazole (SMX) using samples of the same muscle, liver and plasma from chickens administered with SMX. Interlaboratory variation in the determined values were similar to those of other studies determined by gas chromatography and liquid chromatography. It was suggested that the interlaboratory difference in determined SMX residues from chicken tissues did not become problems of using EIA method, in spite of the differences of equipments and operators.

Yeast beta- and beta'-coat proteins (COP). Two coatomer subunits essential for endoplasmic reticulum-to-Golgi protein traffic

To understand better the role of non-clathrin coat proteins in membrane traffic, we have cloned and characterized two essential genes encoding subunits of the yeast coatomer, SEC26 and SEC27. Sec26p is a 109-kDa protein that shares 43% sequence identity with mammalian beta-coat protein (beta-COP). Sec26p-depleted cells accumulate endoplasmic reticulum (ER) forms of secretory precursor proteins, and growth ceases after a dramatic accumulation of ER membranes. Sec26p overproduction partially suppresses sec27-1, a new mutant that shows a temperature-sensitive defect in ER-to-Golgi transport. The SEC27 gene was cloned, and the sequence predicts a 99.4-kDa protein with 45% sequence identity to mammalian beta'-COP. Our sequence data support a two-domain model for the SEC27 protein: a conserved amino-terminal domain, composed of five WD-40 repeats similar to those found in beta-subunits of trimeric G proteins, and a less conserved carboxyl-terminal domain. Genetic interactions connect sec27-1 and sec21-1 (coatomer gamma subunit) with the ARF1 and ARF2 genes and with the SEC22, BET1, and BOS1 genes, which encode membrane proteins involved in ER-to-Golgi transport.

COPII: a membrane coat formed by Sec proteins that drive vesicle budding from the endoplasmic reticulum

In vitro synthesis of endoplasmic reticulum-derived transport vesicles has been reconstituted with washed membranes and three soluble proteins (Sar1p, Sec13p complex, and Sec23p complex). Vesicle formation requires GTP but can be driven by nonhydrolyzable analogs such as GMP-PNP. However, GMP-PNP vesicles fail to target and fuse with the Golgi complex whereas GTP vesicles are functional. All the cytosolic proteins required for vesicle formation are retained on GMP-PNP vesicles, while Sar1p dissociates from GTP vesicles. Thin section electron microscopy of purified preparations reveals a uniform population of 60-65 nm vesicles with a 10 nm thick electron dense coat. The subunits of this novel coat complex are molecularly distinct from the constituents of the nonclathrin coatomer involved in intra-Golgi transport. Because the overall cycle of budding driven by these two types of coats appears mechanistically similar, we propose that the coat structures be called COPI and COPII.

Reconstitution of protein translocation from solubilized yeast membranes reveals topologically distinct roles for BiP and cytosolic Hsc70

We reconstituted prepro-alpha-factor translocation and signal peptide processing using a yeast microsomal detergent soluble fraction formed into vesicles with soybean phospholipids. Reconstituted translocation required ATP, and was deficient when sec63 and kar2 (BiP) mutant cells were used as a source of membranes. Normal translocation was observed with vesicles reconstituted from a mixture of pure wild-type yeast BiP and a soluble fraction of kar2 mutant membranes. Two other heat-shock cognate (hsc) 70 homologs, yeast cytosolic hsc70 (Ssalp) and E. coli dnaK protein did not replace BiP. Conversely, BiP was not active under conditions where translocation into native ER vesicles required cytosolic hsc70. We conclude that cytosolic hsc70 and BiP serve noninterchangeable roles in polypeptide translocation, possibly because distinct, asymmetrically oriented membrane proteins are required to recruit each protein to opposing surfaces of the ER membrane.