Muc4/sialomucin complex, an intramembrane modulator of ErbB2/HER2/Neu, potentiates primary tumor growth and suppresses apoptosis in a xenotransplanted tumor

Overexpression of the membrane mucin MUC4/Sialomucin complex (SMC) has been observed during malignant progression of mammary tumors in both humans and rats, suggesting that deregulation of MUC4/SMC expression might facilitate development of these malignancies. As previously reported, overexpression of SMC results in suppression of both cell adhesion and immune killing of tumor cells. SMC also acts as a ligand for ErbB2/Neu, modulating phosphorylation of the receptor tyrosine kinase in the presence and absence of heregulin. The present studies investigated the effect of Muc4/SMC up-regulation on primary tumor growth using a tetracycline-inducible SMC expression system in a xenotransplanted tumor model. SMC up-regulation provoked rapid growth of transfected A375 melanoma in nude mice. Up-regulation of SMC, however, did not significantly increase proliferation of A375 cells in vitro. Instead, a strong suppression of apoptosis was observed in situ in SMC-overexpressing tumors. These data suggest that Muc4/SMC expression promotes tumor growth in vivo at least in part via suppression of tumor cell apoptosis. Importantly, reduction of apoptosis was also observed in vitro, indicating that anti-apoptotic effect of SMC is independent of tumor-host interactions. These findings strongly suggest that SMC up-regulation alters intracellular signaling to favor cell survival, providing for the first time evidence for the regulation of programmed cell death by a gene of the MUC family.

Poorly vascularized malignant insulinoma displaced the pancreatic ducts around the mass on endoscopic retrograde cholangiopancreatography

A 66-year-old woman with an altered mental status caused by hypoglycemia was referred to Akita City Hospital. Abdominal ultrasonography (US) and endoscopic US revealed an isoechoic mass measuring 25 mm in the head of the pancreas. Endoscopic retrograde cholangiopancreatography (ERCP) revealed that the main pancreatic duct and its branches were displaced around the mass in the head of the pancreas. On arteriography, a poorly vascularized tumor was observed. Dynamic contrast-enhanced computed tomography (CT) showed a low-attenuation mass in the head of the pancreas. A pylorus-preserving pancreaticoduodenectomy was performed. Microscopically, the diagnosis was malignant insulinoma.

Reversal of P-glycoprotein and multidrug-resistance protein-mediated drug resistance in KB cells by 5-O-benzoylated taxinine K

A newly synthesized taxoid originally from the Japanese yew Taxus cuspidata, 5-O-benzoylated taxinine K (BTK) was examined for its ability to reverse P-glycoprotein (P-gp) and multidrug resistance protein (MRP)-mediated multidrug resistance. BTK reversed the resistance to paclitaxel, doxorubicin (ADM), and vincristine (VCR) of KB-8-5 and KB-C2 cells that overexpress P-gp by directly interacting with P-gp. BTK also moderately reversed the resistance to ADM of KB/MRP cells that overexpress MRP. However, BTK neither inhibited the transporting activity of MRP nor reduced intracellular glutathione levels in KB/MRP cells. BTK shifted the distribution of ADM in KB/MRP cells from punctate cytoplasmic compartments to the nucleoplasm and cytoplasm by inhibiting acidification of cytoplasmic organelles. These two functions of BTK make it able to reverse both P-gp- and MRP-mediated MDR. BTK in combination with ADM should be useful for treating patients with tumors that overexpress both P-gp and MRP.

[Pseudomonas aeruginosa]

We investigated the causes of nosocomial infection of P. aeruginosa in a recent outbreak of P. aeruginosa in our hospital. Multi-drug-resistant-P. aeruginosa(MDRPS) that did not produce class B beta-lactamase was isolated from 20(40.0%) patients, occurring in 50 patients hospitalized in the Internal Medicine Ward E in our hospital in 1999 was investigated. All of the patients had brain-vesicular damage as the underlying disease, and 12 patients had been fed by nasal feeding or through a gastric stoma. MDRPS was isolated from sputum(7), urine samples(8), wound discharge(4) and 1 catheter. The bacteria were resistant to piperacillin, ceftazidime, sulbactam/cefoperazone, minocycline and ofloxacin, and in 40% the MIC of the imipenem was more than 8 micrograms/ml. We did not detect MDRPS in any equipment parts or waste water, including the sink in Ward E, but it was detected in the nutrient fluid for nasal feeding and in the line of one patient. The DNA homology of MDRPS isolated from the patient and the nutritive liquid was the same as that of some strains isolated in Ward E, as shown by random amplified DNA polymorphism PCR. In conclusion, we speculated that some nosocomial infections due to MDRPS resistant to imipenem were caused by contaminated nasal feeding.

A novel de novo mutation in the desmin gene causes desmin myopathy with toxic aggregates

OBJECTIVE

To determine the cause and pathogenic mechanisms of a 21-year-old patient's cardioskeletal myopathy. The patient's muscle atrophy and weakness began in distal parts of limbs; cardiac and facial muscles were later involved.

BACKGROUND

Desmin myopathy is a skeletal myopathy often associated with cardiomyopathy, caused by mutations in the desmin gene and characterized by desmin accumulation in affected muscle fibers, a leading marker of myofibrillar myopathies. Two kinds of deletions and seven missense mutations in the desmin gene have been identified.

METHODS

Clinical examination, electron microscopy of muscle tissue, two-dimensional gel electrophoresis, DNA sequencing, restriction enzyme analysis, and gene transfection were performed.

RESULTS

Electron microscopy showed disruption of sarcomeres at Z discs and electron-dense aggregates in biopsied skeletal and heart muscle. Two-dimensional gel electrophoresis of the patient's skeletal muscle proteins showed massive accumulation of desmin. The authors identified a novel desmin mutation, L385P in one allele in the carboxyl end of the rod domain 2B in the patient's leukocytes and skeletal muscle; neither parent had the mutation. Serologic study and DNA markers confirmed the de novo mutation. A peptide harboring desmin rod domains 2A and 2B with L385P tagged with green fluorescent protein induced cytoplasmic aggregates, nuclear DNA condensation, and cell death.

CONCLUSIONS

A novel de novo mutation, L385P, causes desmin myopathy. An expression study indicated the toxic effect of the L385P mutation.

Histopathological study of the effect of phacoemulsification-aspiration on iris muscles

Phacoemulsification-aspiration (PEA) followed by peripheral iridectomy was performed in 10 patients, and the dissected iris fragments were examined by electron microscopy. Organic changes such as cytoplasmic vacuolation and lamellar formation were observed in both the sphincter and dilator muscles of the pupil. No changes in the axons were detected. The same findings were observed when a simian eye was examined after PEA. These results indicate that PEA causes injury to iris muscles.

Zonisamide reduces the increase in 8-hydroxy-2'-deoxyguanosine levels formed during iron-induced epileptogenesis in the brains of rats

PURPOSE

To examine the change of 8-hydroxy-2'deoxyguanosine (8-OHdG) levels, which are used as a marker for oxidative DNA damage, in iron-induced epileptogenic foci of the rat cerebrum.

METHOD

Male Wistar rats were given a cortical injection of ferric chloride, and their 8-OHdG levels were determined over time. Additional animals were pretreated with the antiepileptic drug zonisamide (ZNS) before the ferric chloride injection, and their 8-OHdG levels were compared with the nonpretreated rats.

RESULTS

Fifteen minutes after ferric chloride solution injection, the level of 8-OHdG increased, reaching a maximum 30 minutes after injection. Sixty minutes after injection, the levels coincided with those of controls. ZNS, in concentrations of 50 and 100 mg/kg body weight, prevented the increase of 8-OHdG levels within the cerebrum 30 minutes after iron solution injection.

CONCLUSIONS

These results indicate that the formation of iron-induced epileptogenic foci in rats is related to DNA-damage-induced reactive oxygen species and that the inhibition of 8-OHdG formation by ZNS after iron injection may be due to the drug's antioxidant activity. The data suggest that free radical species known to be formed during iron salts-induced focal epileptogenesis cause damage to isocortical DNA. Furthermore, ZNS appears to inhibit the focal injuring response to DNA that occurs following iron salts-induced acute epileptogenesis.

Rapid oscillation of insulin release by the rat pancreatic islets under stringent Ca2+-free conditions

Oscillation of insulin release by the pancreatic islets was evaluated under stringent Ca(2+)-free conditions for the first time. Isolated single rat islets were exposed to 16.7 mM glucose in the presence of 1.9 mM Ca(2+), or under the stringent Ca(2+)-free conditions (Ca(2+) omission with 1 mM EGTA, 6 microM forskolin and 100 nM phorbol 12-myristate 13-acetate). Fifteen minutes after the initiation of glucose stimulation, effluent was collected at a 6-s interval, insulin was determined in duplicate by a highly sensitive insulin radioimmunoassay, and oscillation and pulsatility of release statistically analyzed. Significant oscillation of insulin release was observed in all islets irrespective of presence and absence of Ca(2+). Significant pulsatility of release was detected in 7 of 11 islets in the presence of Ca(2+) and three of six isl! ets in the absence of Ca(2+). In conclusion, high glucose elicits oscillatory insulin release both in the presence and absence of extracellular Ca(2+).

Potentiation of metastasis by cell surface sialomucin complex (rat MUC4), a multifunctional anti-adhesive glycoprotein

Sialomucin complex (SMC), a rat homologue of the human mucin MUC4, is a large membrane-bound mucin complex, originally isolated from highly metastatic ascites 13762 mammary adenocarcinoma cells. When overexpressed, SMC exerts potent anti-adhesive effects, which sterically disrupt molecular interactions for cell-cell and cell-ECM adhesions. SMC similarly suppresses anti-tumor immunity by inhibition of interactions between cytotoxic lymphocytes and target tumor cells. Previously, recombinant cDNAs for SMC were transfected and inducibly expressed in A375 human melanoma cells using a tetracycline-responsive expression system. In the current studies, we investigated the role of MUC4/SMC in tumor metastasis by regulating SMC expression of tumor transplants in vivo. Intravenous injection of SMC-overexpressing cells resulted in substantially greater lung metastasis than injection of SMC-repressed cells. Injection of SMC-overexpressing cells followed by in vivo downregulation of SMC did not lower the frequency of lung metastasis. Growth of the micrometastatic lesions was the same for all 3 cases in short-term (3-week) assays. Further, subcutaneous injection of A375 cells followed by in vivo induction of SMC overexpression within the solid tumor resulted in spontaneous distant metastasis. These studies suggest that SMC potentiates metastasis by contributing to the establishment of metastatic foci. These studies directly demonstrate for the first time that tumor metastasis can be modulated by the regulation of MUC4/SMC expression.

Potentiation of metastasis by cell surface sialomucin complex (rat MUC4), a multifunctional anti-adhesive glycoprotein

Sialomucin complex (SMC), a rat homologue of the human mucin MUC4, is a large membrane-bound mucin complex, originally isolated from highly metastatic ascites 13762 mammary adenocarcinoma cells. When overexpressed, SMC exerts potent anti-adhesive effects, which sterically disrupt molecular interactions for cell-cell and cell-ECM adhesions. SMC similarly suppresses anti-tumor immunity by inhibition of interactions between cytotoxic lymphocytes and target tumor cells. Previously, recombinant cDNAs for SMC were transfected and inducibly expressed in A375 human melanoma cells using a tetracycline-responsive expression system. In the current studies, we investigated the role of MUC4/SMC in tumor metastasis by regulating SMC expression of tumor transplants in vivo. Intravenous injection of SMC-overexpressing cells resulted in substantially greater lung metastasis than injection of SMC-repressed cells. Injection of SMC-overexpressing cells followed by in vivo downregulation of SMC did not lower the frequency of lung metastasis. Growth of the micrometastatic lesions was the same for all 3 cases in short-term (3-week) assays. Further, subcutaneous injection of A375 cells followed by in vivo induction of SMC overexpression within the solid tumor resulted in spontaneous distant metastasis. These studies suggest that SMC potentiates metastasis by contributing to the establishment of metastatic foci. These studies directly demonstrate for the first time that tumor metastasis can be modulated by the regulation of MUC4/SMC expression.

The efficacy of an antioxidant cocktail on lipid peroxide level and superoxide dismutase activity in aged rat brain and DNA damage in iron-induced epileptogenic foci

Mixed natural antioxidants can be combined in a prophylactic food against age related disease involving reactive oxygen species. beta-Catechin is an antioxidant drink, having free radical scavenging activities. It contains green tea extract as a main component as well as ascorbic acid, sunflower seed extract, dunaliella carotene and natural vitamin E. In the present study, we examined the effect of beta-catechin on lipid peroxide formation and superoxide dismutase (SOD) activity in aged rat brain and the effect on 8-hydroxy-2'-deoxyguanosine (8-OHdG) in ipsilateral cortex, 30 min after ferric chloride solution was injected into the left cortex of rats. beta-Catechin solution was orally administered to aged rats and normal rats for 1 month. One-month administration of beta-catechin solution increased SOD activity in the mitochondria fraction of striatum and midbrain and decreased thiobarbiturate reactive substance formation in the cortex and cerebellum of aged rats. It also inhibited 8-OHdG formation in the ipsilateral cortex 30 min after injection of ferric chloride solution. These results suggest that beta-catechin is a suitable prophylactic beverage against age-related neurological diseases associated with reactive oxygen species.

Calmodulin and Ca2+/calmodulin-binding proteins are involved in Tetrahymena thermophila phagocytosis

The ciliated protist, Tetrahymena thermophila, possesses one oral apparatus for phagocytosis, one of the most important cell functions, in the anterior cell cortex. The apparatus comprises four membrane structures which consist of ciliated and unciliated basal bodies, a cytostome where food is collected by oral ciliary motility, and a cytopharynx where food vacuoles are formed. The food vacuole is thought to be transported into the cytoplasm by a deep fiber which connects with the oral apparatus. Although a large number of studies have been done on the structure of the oral apparatus, the molecular mechanisms of phagocytosis in Tetrahymena thermophila are not well understood. In this study, using indirect immunofluorescence, we demonstrated that the deep fiber consisted of actin, CaM, and Ca2+/CaM-binding proteins, p85 and EF-1alpha, which are closely involved in cytokinesis. Moreover, we showed that CaM, p85, and EF-1alpha are colocalized in the cytostome and the cytopharynx of the oral apparatus. Next, we examined whether Ca2+/CaM signal regulates Tetrahymena thermophila phagocytosis, using Ca2+/CaM inhibitors chlorpromazine, trifluoperazine, N-(6-aminohexyl)-1-naphthalenesulfonamide, and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide HCI. In Tetrahymena, it is known that Ca2+/CaM signal is closely involved in ciliary motility and cytokinesis. The results showed that one of the inhibitors, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide HCl, inhibited the food vacuole formation rather than the ciliary motility, while the other three inhibitors effectively prevented the ciliary motility. Considering the colocalization of CaM, p85, and EF-1alpha to the cytopharynx, these results suggest that the Ca2+/CaM signal plays a pivotal role in Tetrahymena thermophila food vacuole formation.

Presence of bacterial 16S ribosomal RNA gene segments in human intestinal lymph follicles

BACKGROUND

There is currently no information regarding microbial agents inside the intestinal lymph follicles.

METHODS

Biopsy or resected specimens, mostly from macroscopically normal areas, were sectioned with a cryostat. DNA was extracted from microdissected samples, exclusively from the lymph follicle. Amplification of DNA was performed using universal primers designed from conserved regions of bacterial 16S ribosomal RNA (rRNA). Several clones with inserts of around 400 base pairs were subjected to DNA sequence analysis followed by a database homology search.

RESULTS

Bacterial 16S rRNA gene segments were detected in the lymph follicle in 2 of 14 (14%) non-inflammatory bowel disease (IBD) cases, 4 of 14 (28%) Crohn disease cases, and in 2 of 5 (40%) ulcerative colitis cases. Nineteen 16S rRNA gene segments were recognized in the eight positive cases. Five segments showed 100% identity to known bacterial 16S rRNAs, namely staphylococcus species, Streptococcus sanguis, and Paracoccus marcusii. However, the other 14 segments showed below 100% identity, indicating either the presence of unknown bacteria or of bacteria without known DNA data. No single identified or unidentified bacterium, characteristic of IBD, including Mycobacterium paratuberculosis and Listeria monocytogenes, was detected.

CONCLUSIONS

The present study confirms the presence of bacterial 16S rRNA gene segments in human intestinal lymph follicles and paves the way for new investigations into the microbiology of the lymph follicle. Whether or not bacteria inside the lymph follicle is a primary stimulus in IBD has yet to be clarified.

Selective attenuation of metabolic branch of insulin receptor down-signaling by high glucose in a hepatoma cell line, HepG2 cells

The effects of a high concentration of glucose on the insulin receptor-down signaling were investigated in human hepatoma (HepG2) cells in vitro to delineate the molecular mechanism of insulin resistance under glucose toxicity. Treatment of the cells with high concentrations of glucose (15-33 mm) caused phosphorylation of serine residues of the insulin receptor substrate 1 (IRS-1), leading to reduced electrophoretic mobility of it. The phosphorylation of IRS-1 with high glucose treatment was blocked only by protein kinase C (PKC) inhibitors. The high glucose treatment attenuated insulin-induced association of IRS-1 and phosphatidylinositol 3-kinase and insulin-stimulated phosphorylation of Akt. A metabolic effect of insulin, stimulation of glycogen synthesis, was also inhibited by the treatment. In contrast, insulin-induced association of Shc and Grb2 was not inhibited. Treatment of the cells with high glucose promoted the translocation of PKCepsilon and PKCdelta from the cytosol to the plasma membrane but not that of other PKC isoforms. Finally, PKCepsilon and PKCdelta directly phosphorylated IRS-1 under cell-free conditions. We conclude that a high concentration of glucose causes phosphorylation of IRS-1, leading to selective attenuation of metabolic signaling of insulin. PKCepsilon and PKCdelta are involved in the down-regulation of insulin signaling, and they may lie in a pathway regulating the phosphorylation of IRS-1.

Importance of hypercoagulability over hyperglycemia for vascular complication in type 2 diabetes

To critically evaluate the relative importance of coagulation abnormalities over other clinical variables for micro- and macrovascular diabetic complications, prothrombin fragment (F1+2), thrombin-antithrombin III complex (TAT), fibrin degradation product d-dimer, and alpha2 plasmin inhibitor complex were determined in 101 stable, relatively well controlled patients with Type 2 diabetes (the mean HbA1c, age and duration of diabetes, 7.1%, 61 and 7.5 years, respectively). First, incidence and severity of diabetic micro- and macroangiopathies were progressively increased with the severity of coagulation abnormalities. Next, correlation of the four values with the presence of micro- and macrovascular complications, respectively, was analyzed by the multiple logistic regression analysis, with the inclusion of other variables such as age, duration of diabetes, HbA1c, blood pressure, and urinary albumin excretion. With the presence of microangiopathies, F1+2 and systolic blood pressure were significantly related, with the relationship being very strong for the former (P=0.003) and weak for the latter (P=0.035). On the other hand, with the presence of macroangiopathies, F1+2 (P=0.003), TAT (P=0.002), duration of diabetes (P=0.015), and age (P=0.013) were related. Other clinical variables were not significantly related with the presence of complications. Coagulation and fibrinolytic abnormalities are stronger determinants of the presence of diabetic vascular complications than other clinical variables including the degree of glycemia, in stable, relatively well controlled patients with Type 2 diabetes.

Ultrasonography of Zenker's diverticulum: special reference to differential diagnosis from thyroid nodules

There have been only two case reports so far in literature on ultrasonographic features of Zenker's diverticulum. We report a case of Zenker's diverticulum and discuss the ultrasonographic images in comparison with those of thyroid nodules. Awareness of changeable internal echoes and not mistaking strong echogenic foci caused by air for calcification were most important for making the differential diagnosis of Zenker's diverticulum from thyroid nodules.

Cerulenin, an inhibitor of protein acylation, selectively attenuates nutrient stimulation of insulin release: a study in rat pancreatic islets

Nutrients such as glucose stimulate insulin release from pancreatic beta-cells through both ATP-sensitive K+ channel-independent and -dependent mechanisms, which are most likely interrelated. Although little is known of the molecular basis of ATP-sensitive K+ channel-independent insulinotropic nutrient actions, mediation by cytosolic long-chain acyl-CoA has been implicated. Because protein acylation might be a sequel of cytosolic long-chain acyl-CoA accumulation, we examined if this reaction is engaged in nutrient stimulation of insulin release, using cerulenin, an inhibitor of protein acylation. In isolated rat pancreatic islets, cerulenin inhibited the glucose augmentation of Ca2+-stimulated insulin release evoked by a depolarizing concentration of K+ in the presence of diazoxide and Ca2+-independent insulin release triggered by a combination of forskolin and phorbol ester under stringent Ca2+-free conditions. Cerulenin inhibition of glucose effects was concentration dependent, with a 50% inhibitory concentration (IC50) of 5 microg/ml and complete inhibition at 100 microg/ml. Cerulenin also inhibited augmentation of insulin release by alpha-ketoisocaproate, a mitochondrial fuel. Furthermore, cerulenin abolished augmentation of both Ca2+-stimulated and Ca2+-independent insulin release by 10 micromol/l palmitate, which causes palmitoylation of cellular proteins. In contrast, cerulenin did not attenuate insulin release elicited by nonnutrient secretagogues, such as a depolarizing concentration of K+, activators of protein kinases A and C, and mastoparan. Glucose oxidation, ATP content in islets, and palmitate oxidation were not affected by cerulenin. In conclusion, cerulenin inhibits nutrient augmentation of insulin release with a high selectivity. The finding is consistent with a prominent role of protein acylation in the process of beta-cell nutrient sensing.

Functional comparison between YCF1 and MRP1 expressed in Sf21 insect cells

YCF1 is a yeast vacuole membrane transporter involved in resistance to Cd(2+) and to exogenous glutathione S-conjugate precursors. MRP1 contributes to multidrug resistance (MDR) in tumor cells. MRP1 and YCF1 have extensive amino acid sequence homology (63% amino acid similarity). We expressed MRP1 or YCF1 in insect cell membranes and compared their functions to know more about their structure-function relationships. YCF1 and MRP1 with His epitopes were expressed in Sf21 insect cells; both of them in the plasma membrane. The ATP-dependent transport of [(3)H]LTC(4) in Sf/YCF1-His vesicles was osmotically sensitive and showed saturable kinetics with an apparent K(m) of 758 nM for LTC(4) and 94 microM for ATP which were similar to those in yeast cells. The K(m) of YCF1 for LTC(4) (758 nM) was sevenfold higher than that of MRP1 (108 nM). MK-571 and ONO-1078, reversing agents for MRP1-mediated MDR, considerably inhibited the transport of LTC(4) by both YCF1 and MRP1. However, PAK-104P, a pyridine analog that reverses MDR associated with P-gp and MRP1, inhibited the transporting activity of MRP1 stronger than that of YCF1. KE1, another MDR reversing agent, moderately inhibited the transport of LTC(4) by MRP1 but not that of YCF1. In conclusion, we successfully expressed yeast YCF1 in Sf21 insect cells and found that the localization of the protein was different from that in yeast. The function of YCF1 in Sf21 insect cells was similar but not identical to that of MRP1.

Copper-transporting P-type adenosine triphosphatase (ATP7B) is associated with cisplatin resistance

The accumulation of cisplatin is decreased in many cisplatin-resistant cell lines, and an active efflux pump for cisplatin exists in some of them, but it has not yet been identified. In this study, we transfected the copper-transporting P-type ATPase cDNA (ATP7B) into human epidermoid carcinoma KB-3-1 cells. The transfectant, KB/WD cell line, which overexpressed the P-type ATPase, ATP7B, was resistant to both cisplatin (8.9-fold) and copper (2.0-fold). The accumulation of cisplatin in KB/WD cells was lower than in mock-transfected KB/CV cells, and the efflux of cisplatin from KB/WD cells was enhanced compared with KB/CV cells. KB/WD cells were sensitive to other heavy metals, such as antimony, arsenate, arsenite, cadmium, and cobalt. ATP7B was overexpressed in cisplatin-resistant prostate carcinoma PC-5 cells but not in the parental PC-3 cells and the revertant PC-5R cells. ATP7B may be involved in cisplatin resistance in some tumors.

Addition of antibacterial agents to MMA-TBB dentin bonding systems--influence on tensile bond strength and antibacterial effect

To produce a bonding system which has both high bond strength and antibacterial properties, an antibacterial agent (vancomycin: VCM or metronidazol: MN) was added to the PMMA powder of 4-META/MMA-TBB resin (CB). The influence of the addition of an antibacterial agent on tensile bond strength to dentin and the antibacterial effect were investigated in this study. Forty-seven freshly extracted bovine first or second incisors were used to measure the tensile bond strength to dentin. The bond strengths to bovine dentin were not significantly decreased by addition of VCM (1%, 2%, 5%), or MN (1%) to CB (p < 0.05). The antibacterial effect of CB containing antibacterial agent on six strains of bacteria was investigated by the agar plate diffusion method, analyzing the appearance of the inhibition zone around a resin disk following anaerobic culturing. The resin disks containing VCM showed antibacterial effects on all of the strains examined; the widths of the inhibition zones were 4-15 mm. The resin disks containing MN showed antibacterial effects on three strains; the widths of the inhibition zones were 0-4 mm. It was thus possible to produce a bonding system with both antibacterial effect and high tensile bond strength by addition of VCM to PMMA powder.

[Detection of extended spectrum beta-lactamases producing Enterobacteriaceae in feces]

A study was made of 366 feces for detection of extended spectrum beta-lactamases producing Enterobacteriaceae from feces. The selective agar was used for modified drigalski agar (Eiken Chemical Co., LTD) with 2 micrograms/ml cefotaxime (ESBL screen agar). 92 strains of Enterobacteriaceae, 41 Escherichia coli, 15 Citrobacter freundii, 13 Enterobacter cloacae, 11 Klebsiella pneumoniae, and other 12, were isolated from ESBL screen agar. And, R-plasmid that were selected by 2 micrograms/ml cefotaxime were transferred by conjugation from two of the 92 strains. These strain were E. coli TH9809927 and Proteus mirabilis TH9808262 that were amplified by "Toho-1 type" primer. The clude enzyme from two strains (donor) and transconjugants were especially hydrolysed cepharoridine and cefotaxime. Accordingly, two strains (0.5%) were detected as ESBL producers. We think that the result of our survey suggests the increase of ESBLs producing bacterial infection in Japan, and believe that there is a trend of infection of its by surveilance of the feces.

Iatrogenic GB virus C/hepatitis G virus infection in an area endemic for hepatitis C virus

GB virus C/hepatitis G virus (GBV-C/HGV) is reported to be transmitted by blood products. This study reports infection with GBV-C/HGV from Area-O of town T, an area of high prevalence of antibody to hepatitis C virus (anti-HCV). Four hundred and thirty-five inhabitants of Area-O in town T were examined. Three hundred and forty-three inhabitants of Area-H in town T (where differences of age or sex are not markedly different to Area-O) were studied as controls. We investigated the virus markers and conducted a survey of life history in both areas. The seroprevalence of anti-HCV and GBV-C/HGV markers in Area-O was 17.7% and 11.7%, significantly higher than in Area-H (1.5% and 4.4%). The prevalence of GBV-C/HGV markers was significantly higher in the anti-HCV-positive group than in the sero-negative group. Anti-HCV- or GBV-C/HGV positive subjects tended to have a history of intravenous medications at hospital C in town T, suggesting iatrogenic infection through insufficient sterilization of needles and/or syringes.

Study of early pregnancy factor (EPF) in equine (Equus caballus)

PROBLEM

Early pregnancy factor (EPF) is an immunosuppressive protein detected in the early pregnancy serum. We have already reported that we developed the rosette inhibition test for mare EPF and detected EPF in thoroughbreds. The aim of this study was to determine whether or not our method could be used clinically.

METHODS OF STUDY

The rosette inhibition test for equine EPF was carried out on serum from six nonpregnant and six pregnant Shetland ponies, a female and a male Chinese pony, and four nonpregnant and 13 pregnant thoroughbred mares. In the thoroughbreds sera were collected during the pregnancy period. Furthermore, we measured progesterone and detected pregnant mare serum gonadotrophin (PMSG) in order to confirm pregnancy of the Chinese pony 3 and 6 months after mating.

RESULTS

In the nonpregnant Shetland ponies, the rosette inhibition titre (RIT) was 6.0+/-1.0 and EPF was negative. In contrast, in the pregnant ponies, the RIT was 9.2+/-0.4 and EPF was positive. Based on these results, we diagnosed pregnancy of the Chinese pony. The RIT of the female Chinese pony (3 months after mating) was above 10 and EPF was positive. Furthermore, we detected PMSG and progesterone in the serum of this pony. EPF appeared in the maternal blood circulation at 24-72 hr after mating, it was detected until the second trimester, and after that it disappeared from the maternal serum.

CONCLUSIONS

The pony's EPF was detected by using the same rosette inhibition test as in the thoroughbred and was present from 24 to 72 hr after mating until the second trimester. The results indicated that our method was useful for pregnancy diagnosis of Equine.

Analysis of biochemical and virological efficacy of human lymphoblastoid interferon (IFN) in patients with compensated type C liver cirrhosis: comparative study between increase in individual IFN dose and prolonging of treatment period, using a multicenter randomized controlled trial

A controlled trial was conducted to compare the efficacy of interferon (IFN) between two groups of patients with type C liver. Thirty-five patients were randomly assigned to group A (17 patients) or group B (18 patients). The former received 3 megaunits (MU) of human lymphoblastoid IFN six days per week for two weeks, followed by three days per week for 50 weeks; the latter group received 6 MU six days per week for two weeks followed by three days per week for 24 weeks. The percentages of biological sustained responders (B-SR) and virological sustained responders (V-SR) were 29.4 and 23.5%, respectively, in group B, and 17.6% for both in group A. The therapeutic effects were not different between two groups. HCV genotype 2 accounted for significantly higher percentage of B-SR and V-SR (both 57.1%, respectively). These findings indicate that IFN is effective in type C cirrhosis with genotype 2.

[A SHV-derived extended-spectrum beta-lactamase (SHV-12) produced by an Escherichia coli recovered from wound abscess in post operative case with rectal carcinoma]

A 62-year-old woman admitted for rectal carcinoma suffered from a post-operative bacterial infection. Oxy-imino-beta-lactams including cefotiam (CTM) and cefozopran (CZOP) were prescribed for this case, but the patient developed a wound abscess followed by peritonitis. She recovered from the bacterial infection after drainage and recurrent washing of the abscess. An ephemeral aggravation of infectious signs was observed just after creation of an artificial anus, and CZOP was again administered, and no evident bacterial infection occurred. The patient recovered, then was followed as an outpatient to date. A CAZ-resistant (MIC, > 16 micrograms/ml) E. coli was recovered from pus of her wound abscess. Since the CAZ-resistance decreased (MIC, 64 micrograms/ml-->0.13 microgram/ml) by the presence of clavulanate (CVA) in this isolate, this strain was speculated to be an extended spectrum beta-lactamase (ESBL) producer at an early stage of infection. A similar strain was also isolated from the feces. Therefore, we immediately took measures to block the nosocomial spread of this microorganism, and we succeeded in preventing a nosocomial outbreak of this strain. It was later confirmed by PCR analysis and DNA sequencing analysis that this CAZ-resistant E. coli strain produces an ESBL (SHV-5-2a = SHV-12). This is the first report of a case of infection with SHV-derived ESBL producing E. coli strain in Japan. We are concerned that further dissemination of this kind of microorganism might occur in the near future also in Japan, as it has been widely observed in European countries and the US. We believe that it will be very important to distinguish the type of beta-lactamases for rigorous bacterial infection control with the prudent use of antibiotics. In other words, we in Japan must recall that various gram-negative bacterial species that produce TEM-, SHV-derived ESBLs, Toho-1, AmpC, or IMP-1 are already widespread. Thus, we should take this fact into consideration when we do antibiotic susceptibility tentings and interpretation of the results for promotion of accurate chemotherapy.

Multiple facets of sialomucin complex/MUC4, a membrane mucin and erbb2 ligand, in tumors and tissues (Y2K update)

Sialomucin complex (SMC, MUC4) is a high Mr glycoprotein heterodimer, composed of mucin (ASGP-1) and transmembrane (ASGP-2) subunits. ASGP-2 contains two EGF-like domains and acts as an intramembrane ligand for the receptor tyrosine kinase ErbB2. Transfection studies with SMC DNAs showed that SMC expression could markedly reduce both cell-cell and cell-matrix interactions in vitro and increase the growth of primary tumors and the formation of metastatic foci of human A375 melanoma cells as xenotransplants in nude mice, possibly through the ability to suppress apoptosis. SMC is expressed in most vulnerable epithelia as a protective agent, which is found in both membrane and soluble forms at luminal surfaces and secreted into fluids such as milk and tears. SMC appears to be constitutively expressed by most accessible epithelia, notable exceptions being the mammary gland and uterine luminal epithelium, in which it is tightly regulated during pregnancy. Down-regulation at the luminal uterine surface appears necessary for blastocyst implantation. TGF-b is a potent repressor of SMC expression in the mammary gland and uterus, though by different mechanisms. These combined results suggest that SMC has multiple functions in epithelia and is tightly regulated in those tissues where its special functions are required.

Comparison of differential diagnostic capabilities of 201Tl scintigraphy and fine-needle aspiration of thyroid nodules

We assessed the ability of 201TI planar scintigraphy and fine-needle aspiration (FNA) biopsy to differentiate malignant from benign lesions by comparing the findings of these techniques with those of surgical histopathology for 107 patients with 109 thyroid nodules.

METHODS

201TI (74 MBq) was injected intravenously, and an early image and a delayed image were acquired after 10 and 120 min, respectively, for 10 min each. For 201TI planar scintigraphy, accumulation of the tracer in the nodules was visually scored and the nodules were grouped. Group A showed high activity in both early and delayed images. Group B revealed high activity in only the early image. Group C showed activity in the early image equal to that in normal tissues. Quantitative calculation of the washout rate was less than 0 in group CI and 0 or higher in group CII. Group D revealed low activity in the early image and variable activity in the delayed image. Three differential diagnosis methods were used for 201TI planar scintigraphy: method 1, in which only group A was considered malignant; method 2, in which both group A and group B were considered malignant; and method 3, in which groups A, B and CI were considered malignant. FNA results were assessed and classified by experienced pathologists. Two differential diagnosis methods were used for FNA: method a, in which malignancy was assigned to class IV (probably malignant or higher), and method b, in which malignancy was assigned to class III (possibly malignant or higher).

RESULTS

Concerning 201TI methods 1, 2 and 3, sensitivity was 74.0%, 84.0% and 92.0%, respectively; specificity was 83.1%, 64.4% and 54.2%, respectively; and accuracy was 78.9%, 73.4% and 71.6%, respectively. For FNA, method a and method b had a sensitivity of 36.0% and 50.0%, respectively, and a specificity of 96.6% and 84.7%, respectively. The accuracy of both methods was 68.8%. For follicular lesions, sensitivity ranged from 80.0% to 90.0% for 201TI scintigraphy and from 10.0% to 30.0% for FNA.

CONCLUSION

201TI planar scintigraphy was found to be easier to use and more accurate than FNA in the differentiation of diagnosis of benign and malignant thyroid nodules based on visual scoring combined with quantitative evaluation.

GB virus C infection: clinical significance

GB virus C (GBV-C) RNA positivity rates were examined in serum specimens from 231 patients with liver disease (23 patients with hepatitis B, 175 patients with hepatitis C, five patients with hepatitis B virus plus hepatitis C virus coinfection, and 28 patients with non-A, non-B, non-C hepatitis) to clarify the clinical significance of this virus. GBV-C RNA was detected in none of 12 patients with fulminant hepatitis, one of two patients with acute hepatitis positive for hepatitis B surface antigen and one of four patients with acute non-A, non-B, non-C hepatitis. Pathogenetic involvement of GBV-C was suspected in some patients in the latter group. Among patients with the non-B, non-C type of chronic disease, one of seven with cirrhosis (14%) and none with chronic hepatitis or hepatocellular carcinoma were GBV-C-positive. In chronic hepatitis C patients who had received interferon treatment, no difference was found in clinical findings, alanine aminotransferase (ALT) concentrations, histology or response to interferon between 11 patients who were GBV-C RNA-positive and 101 patients who were GBV-C RNA-negative. Moreover, changes in ALT after interferon therapy showed no relation to positivity for GBV-C RNA. On the basis of these findings, GBV-C appears to be an unlikely cause of initiation or progression of chronic hepatic diseases.

Cloning and characterization of two neural-salient serine/arginine-rich (NSSR) proteins involved in the regulation of alternative splicing in neurones

BACKGROUND

In neurones, alternative splicing regulates the functions of many gene products. However, the molecular basis of neural-specific splicing, and how splicing regulation is modulated in different neurones remains to be determined.

RESULTS

We cloned two new SR proteins, Neural-salient SR proteins (NSSR) 1 and 2, which are present at higher levels in brain and testis. During the differentiation, NSSR 1 is detected only in the neuronal stage. Both the purified recombinant NSSR 1 and 2 proteins enhance the in vitro splicing activity of nuclear extract. Moreover, recombinant NSSR 1 protein enhances the assembly of ribonucleoprotein complexes with S100 fraction. Over-expression of NSSR 2 prevents the inclusion of either the Flip or Flop exons in the splicing of the GluR-B gene, resulting in an increase in the abnormal exon-skipping product. In contrast, transient transfection with NSSR 1 promotes the inclusion of the Flip exon so that the abnormal product is spliced to the mature spliced form. This suppression of exon skipping by NSSR 1 is observed even with co-transfection of NSSR 2.

CONCLUSIONS

NSSR 1 and 2 were cloned from mouse cDNA libraries. Results indicate that NSSR 1 may play a crucial role in the regulation of alternative splicing in neurones.

Olfactory neurons expressing closely linked and homologous odorant receptor genes tend to project their axons to neighboring glomeruli on the olfactory bulb

We have characterized two separate odorant receptor (OR) gene clusters to examine how olfactory neurons expressing closely linked and homologous OR genes project their axons to the olfactory bulb. Murine OR genes, MOR28, MOR10, and MOR83, share 75-95% similarities in the amino acid sequences and are tightly linked on chromosome 14. In situ hybridization has demonstrated that the three genes are expressed in the same zone, at the most dorsolateral and ventromedial portions of the olfactory epithelium, and are rarely expressed simultaneously in individual neurons. Furthermore, we have found that olfactory neurons expressing MOR28, MOR10, or MOR83 project their axons to very close but distinct subsets of glomeruli on the medial and lateral sides of the olfactory bulb. Similar results have been obtained with another murine OR gene cluster for A16 and MOR18 on chromosome 2, sharing 91% similarity in the amino acid sequences. These results may indicate an intriguing possibility that olfactory neurons expressing homologous OR genes within a cluster tend to converge their axons to proximal but distinct subsets of glomeruli. These lines of study will shed light on the molecular basis of topographical projection of olfactory neurons to the olfactory bulb.

Genetic relationship and distribution of the Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (Sus scrofa riukiuanus) analysed by mitochondrial DNA

Mitochondrial genetic variations were used to investigate the relationships between two Japanese wild boars, Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (S.s. riukiuanus). Nucleotide sequences of the control (27 haplotypes) and cytochrome b (cyt-b) regions (19 haplotypes) were determined from 59 Japanese wild boars, 13 Ryukyu wild boars and 22 other boars and pigs. From phylogenetic analyses, the mtDNA of Ryukyu wild boar has a distinct lineage from that of Japanese wild boar, which was classified into the Asian pig lineage. This result suggests that the Ryukyu wild boar has a separate origin from the Japanese wild boar.

Ac as a tool for the functional genomics of rice

To examine whether the maize autonomous transposable element Ac can be used for the functional analysis of the rice genome, we used Southern blot analysis to analyze the behaviour of Ac in 559 rice plants of four transgenic families through three successive generations. All families showed highly active transposition of Ac, and 103 plants (18.4%) contained newly transposed Ac insertions. In nine of the 12 independent transpositions analyzed, their germinal transmission was detected. Partial sequencing of 99 Ac-flanking sequences revealed that 21 clones exhibited significant similarities with protein-coding genes in databases and four of them matched rice cDNA sequences. These results indicate preferential Ac transposition into protein-coding rice genes. To examine the feasibility of PCR-based screening of gene knockouts in rice Ac plants, we prepared bulked genomic DNA from the leaves of approximately 6000 rice Ac plants and pooled the DNA according to a three-dimensional matrix. Of 14 randomly selected genes, two gene knockouts were identified, and one encoding a rice cytochrome P450 (CYP86) gene was shown to be stably inherited to the progeny. Together, these results suggest that Ac can be efficiently used for the functional analysis of the rice genome.

Augmentation of Ca2+-stimulated insulin release by glucose and long-chain fatty acids in rat pancreatic islets: free fatty acids mimic ATP-sensitive K+ channel-independent insulinotropic action of glucose

Glucose augments Ca2+-stimulated insulin release from the pancreatic beta-cell in an ATP-sensitive K+ channel (K(ATP) channel)-independent manner. In studying the mechanisms underlying this action, we used rat pancreatic islets and examined the effects of exogenous free fatty acids (FFAs), which are precursors of long-chain acyl-CoA (LC-CoA), on KCl-induced Ca2+-stimulated insulin release. Myristate, palmitate, and stearate augmented insulin release induced by 50 mmol/l KCl in the presence of 2.8 mmol/l glucose. Added acutely, their potency was weak compared with that of glucose-induced augmentation. The FFA-induced augmentation became much greater, however, when islets were preincubated with FFAs under stringent Ca2+-free conditions (with 1 mmol/l EGTA) before the KCl stimulation. Under these conditions, 16.7 mmol/l glucose augmented 13-fold insulin release induced by 50 mmol/l KCl, whereas palmitate or myristate (both at a free concentration of 10 micromol/l) produced 5.8- and 5.2-fold augmentations. Effects of FFAs and glucose were concentration-dependent. The temporal profiles of augmentation induced by 11.1 mmol/l glucose and 10 micromol/l palmitate were similar. Glucose and palmitate caused almost identical augmentation patterns for the initial 10 min of stimulation; subsequently, glucose augmentation was better sustained than palmitate augmentation. This suggests the existence of a longer-term glucose-specific signaling moiety that cannot be mimicked by FFAs. Our results provide direct evidence that FFAs can mimic the K(ATP) channel-independent action of glucose. Taking these results together with previous results, we conclude that glucose augments Ca2+-stimulated insulin release, at least in part, by increasing malonyl-CoA and cytosolic LC-CoA. However, one or more other glucose-specific signaling molecules are required for the full expression of augmentation.

Tauroursodeoxycholic acid enhances phagocytosis of the cultured rat Kupffer cell

BACKGROUND

Ursodeoxycholic acid is used in the treatment of acute and chronic intrahepatic cholestasis because it ameliorates cholestasis and protects hepatocytes. However, few studies have examined the effect of bile acids on the function of Kupffer cells.

METHODS

The effect of various bile acids on cultured rat Kupffer cells was studied in terms of phagocytic activity in response to latex particles and morphological alterations. Video-enhanced differential interference contrast microscopy was used.

RESULTS

Taurochenodeoxycholic acid and taurodeoxycholic acid reduced the number of latex particles incorporated into Kupffer cells, but taurocholic and tauroursodeoxycholic acids enhanced phagocytosis of latex particles. Inhibition of phagocytosis by taurochenodeoxycholic acid or taurodeoxycholic acid was essentially dose dependent. Tauroursodeoxycholic acid also enhanced phagocytosis by Kupffer cells in which phagocytosis had been reduced by pretreatment with taurochenodeoxycholic acid or taurodeoxycholic acid. Incorporated latex particles had a distinct translocation speed of 0.084+/-0.024 microm/s (mean maximum speed+/-SD); the speed was in the same range with tauroursodeoxycholic acid treatment. Tauroursodeoxycholic acid induced a 56% expansion of cytoplasm, associated with increased ruffling and movement of intracellular organelles.

CONCLUSIONS

These observations suggest that tauroursodeoxycholic acid enhances membrane trafficking without changing translocation speed.

Different changes in concentrations of monoamines and their metabolites and amino acids in various brain regions by the herbal medicine/Toki-Shakuyaku-San between female and male senescence-accelerated mice (SAMP8)

Due to it's estrogen-secreting qualities, a Japanese herbal medicine, Toki-Shakuyaku-San may have a potential role for Alzheimer's disease in women. The effect of treatment with Toki-Shakuyaku-San testing on concentrations of monoamines, their metabolites and amino acids in the cortex, hippocampus and striatum of senescence accelerated mice (SAMP8) was examined and sex differences of SAMP8 and ddY mice was studied. In the female SAMP8, concentrations of gamma-aminobutyric acid, alanine, and glycine were elevated in three regions after treatment. The concentration of glutamate was decreased in the cortex, hippocampus, and striatum of female and male SAMP8 and not in female and male ddY mice. These results suggest that different effects of Toki-Shakuyaku-San treatment on concentrations of monoamines, their metabolites and amino acids in the brain tissue may be due to its stimulation of secreted estrogen on neurons.

High-dose natural interferon-alpha therapy for chronic hepatitis C with a high viral load: predictors of efficacy. The Aomori, Akita and Iwate Areas Viral Hepatitis Research Group

BACKGROUND

The effectiveness of interferon against hepatitis C has been found to be greatly affected by viral factors. However, few controlled interferon trials have involved seemingly intractable cases of chronic hepatitis C.

METHODS

In 44 patients with high hepatitis C virus RNA levels (> or = 10(5) copies/mL), we carried out a prospective, controlled study of two natural interferon-alpha regimens, seeking predictors of therapeutic efficacy. Total natural interferon-alpha doses over 6 months in two groups were 780 and 840 million units, respectively.

RESULTS

High therapeutic efficacy was achieved with no significant outcome difference between the regimens. The virus eradication rate was 35% and the rate of sustained biochemical response was 45% for both regimens. Multivariate logistic regression analysis identified viral genotype as the only significant predictor of success in viral eradication.

CONCLUSIONS

Hepatitis C virus genotype 2 showed high sensitivity to interferon-alpha and this therapy can be recommended even for patients with a high viral load of this genotype. In contrast, with genotype 1b, cure was extremely difficult in cases with 10(7) or more copies/mL with a single 6-month course of interferon-alpha.

Effects of Secondary Polymer Covalently Attached to Monodisperse, Poly(maleic anhydride-styrene)-Modified Colloidal Silica on Dispersibility in Organic Solvent

Effects of surface-grafted polymer on the dispersibility of polymer-silica composite particles in ethyl acetate-methanol cosolvent were investigated. The composite particles were prepared by a two-step modification of monodisperse colloidal silica (120 nm in diameter). Modifications were carried out by first reacting the surface silanol of the colloidal silica with maleic anhydride-styrene copolymer silane coupling agent to prevent aggregation and then grafting, in acetone or tetrahydrofuran, amino group-terminated poly(methyl acrylate), poly(methyl methacrylate), or polystyrene to the maleic anhydride moiety on the surface. For poly(methyl acrylate) and poly(methyl methacrylate) graftings, composite particles with long polymer chains aggregated in methanol-rich cosolvent due to insoluble secondary polymer chain interaction among the particles. Particles with a small amount of relatively low-molecular-weight secondary polymer were dispersible in the methanol content range from 0 to 90 vol%. Polystyrene-modified particles never aggregated, even in 90 vol% methanol solution. An ESR study of the suspension in ethyl acetate-hexane cosolvent suggested that the dispersibility of these composite particles in ethyl acetate-rich solution is attributable to steric repulsion between solvated and expanded secondary polymer chains among the particles. The dispersibility of the composite particles in methanol-rich solution was controlled by a delicate balance between the electrostatic repulsion and the interparticle attraction due to the desolvated and insoluble polymer chain interaction among the particles. Copyright 1999 Academic Press.

Decreased tear lactoferrin concentration in patients with chronic hepatitis C

BACKGROUND/AIMS

Decreased tear volume in patients with chronic hepatitis C has been reported in the literature. Lactoferrin is abundantly present in human tears, the main source of which is the acini of the lacrimal glands. In this study tear lactoferrin levels were measured to investigate the dry eye condition of patients with chronic hepatitis C.

METHODS

Lactoferrin in tears/fluid was measured by a radial immunodiffusion assay in 42 patients with chronic hepatitis C. The rate of lacrimal secretion was determined by the cotton thread test. Rose bengal staining of the ocular surface was also performed.

RESULTS

Only three patients out of 42 complained of dry eye sensation and, in 31 patients, six showed positive results on the rose bengal staining test of the ocular surface. The lactoferrin concentration of tear fluid in the chronic hepatitis C group (1.42 (SD 0.56) mg/ml) was significantly lower than in the control group (1.90 (0.62) mg/ml; p <0.00048). The cotton thread test results in the chronic hepatitis C group (12.9 (5. 5) mm) were significantly lower than in the control group (17.9 (5. 3) mm; p<0.00048). Also, in the chronic hepatitis C group, tear lactoferrin concentration correlated with the results of the cotton thread test (r = 0.35, p<0.05).

CONCLUSION

Chronic hepatitis C patients showed both decreased tear volume, and decreased tear lactoferrin concentration. These findings suggest that there may be dysfunction of the lacrimal glands in patients with chronic hepatitis C, which may account for the mild dry eye.

Overexpression of sialomucin complex, a rat homologue of MUC4, inhibits tumor killing by lymphokine-activated killer cells

Sialomucin complex (SMC) is a large heterodimeric glycoprotein complex composed of a mucin subunit ascites sialoglycoprotein-1 and a transmembrane subunit ascites sialoglycoprotein-2. It is a rat homologue of human mucin gene MUC4 and is abundantly expressed on the cell surface of highly metastatic ascites 13762 rat mammary adenocarcinoma cells. Because of their extended and rigid structures, mucin-type glycoproteins are suggested to have suppressing effects on cell-cell and cell-matrix interactions. During the metastatic process, these effects presumably cause tumor cell detachment from the primary tumor mass and facilitate escape of the tumor cells from immunosurveillance. Analyses of human breast cancer cells in solid tumors and tumor effusions showed that the more aggressive cells in effusions are stained with polyclonal antibodies against SMC more frequently than cells in solid tumors, suggesting a role for MUC4/SMC in tumor progression and metastasis. Previously, we generated recombinant cDNAs for SMC that vary in the number of mucin repeats to study the putative functions of SMC in tumor metastasis. These cDNAs were transfected into human cancer cell lines and tested for the effect of the expression of this gene. Here, using a tetracycline-responsive inducible expression system, we demonstrate that overexpression of SMC masks the surface antigens on target tumor cells and effectively suppresses tumor cell killing by cytotoxic lymphocytes. This effect results from the ability of SMC to block killer cell binding to the tumor cells and is dependent on both overexpression of the mucin and the number of mucin repeats in the expressed SMC. These results provide an explanation for the proposed role of SMC/MUC4 in tumor progression.

cAMP enhances insulin secretion by an action on the ATP-sensitive K+ channel-independent pathway of glucose signaling in rat pancreatic islets

Cyclic AMP potentiates glucose-stimulated insulin release by actions predominantly at a site, or sites, distal to the elevation of the cytosolic free Ca2+ concentration ([Ca2+]i). Glucose also acts at a site, or sites, distal to the elevation of [Ca2+]i via the ATP-sensitive K+ channel (K+ATP channel)-independent signaling pathway. Accordingly, using rat pancreatic islets, we studied the location of the action of cAMP and its interaction with the glucose pathway. Forskolin, an activator of adenylyl cyclase, raised intracellular cAMP levels and enhanced KCl-induced (Ca2+ -stimulated) insulin release in the presence, but not in the absence, of glucose. Thus, cAMP has no direct effect on Ca2+ -stimulated insulin release. The interaction between cAMP and glucose occurs at a step distal to the elevation of [Ca2+]i because forskolin enhancement of KCl-induced insulin release, in the presence of glucose, was demonstrated in the islets treated with diazoxide, a K+ATP channel opener. The enhancement of insulin release was not associated with any increase in [Ca2+]i. Furthermore, the interaction between cAMP and glucose was unequivocally observed even under stringent Ca2+ -free conditions, indicating the Ca2+ -independent action of cAMP. This action of cAMP is physiologically relevant, because not only forskolin but also glucagon-like peptide 1, glucose-dependent insulinotropic polypeptide, and pituitary adenylyl cyclase activating polypeptide exerted similar actions. In conclusion, the cAMP/protein kinase A pathway has no direct effect on Ca2+ -stimulated insulin exocytosis. Rather, it strongly potentiates insulin release by increasing the effectiveness of the K+ATP channel-independent action of glucose.

An enhanced active efflux of CPT-11 and SN-38 in cisplatin-resistant human KB carcinoma cells

Cisplatin-resistant KCP-4 cells were 12.4- and 31.6-fold more resistant to CPT-11 and SN-38 than parental KB-3-1 cells, respectively. We studied the mechanism of cross-resistance to CPT-11 and SN-38. Our previous study showed that multidrug resistance protein (MRP), canalicular multispecific organic anion transporter (cMOAT) and P-glycoprotein (P-gp) were not expressed in KCP-4 cells (Chen, Z.-S. et al., Exp. Cell Res., 240 (1998) 312-320, and Chuman, Y. et al., Biochem. Biophys. Res. Commun., 226 (1996) 158-165). The accumulation of both CPT-11 and SN-38 in KCP-4 cells was lower than that in KB-3-1 cells. The ATP-dependent efflux of CPT-11 and SN-38 from KCP-4 cells was enhanced compared with that from KB-3-1 cells. DNA topoisomerase (topo) I expression, topo I activity, topo I-mediated cleavable complex, and the sensitivity to SN-38 of DNA topo I in KCP-4 were similar to those in KB-3-1 cells. Furthermore, the conversion of CPT-11 to SN-38 in the two cell lines was also similar. The transport of LTC4 in KCP-4 membrane vesicles was competitively inhibited by bis-(glutathionato)-platinum (II) (GS-Pt), CPT-11 and SN-38. These findings suggested that an unknown transporter distinct from P-gp, MRP or cMOAT is expressed in KCP-4 cells and transports CPT-11 and SN-38.

An intramembrane modulator of the ErbB2 receptor tyrosine kinase that potentiates neuregulin signaling

The ErbB2 receptor tyrosine kinase plays a critical role in a variety of developmental processes, and its aberrant activation may contribute to the progression of some breast and ovarian tumors. ASGP2, a transmembrane glycoprotein found on the surface of the highly metastatic ascites 13762 rat mammary adenocarcinoma cell line, is constitutively associated with ErbB2 in these cells and in mammary tissue from pregnant rats. Expression studies indicate that ASGP2 interacts directly and specifically with ErbB2 through one of its epidermal growth factor-like domains and that the co-expression of the two proteins in the same cell dramatically facilitates their direct stable interaction. Ectopic expression of ASGP2 in human melanoma tumor cells potentiates the response of endogenous ErbB2 to the neuregulin-1 growth factor. These observations point to a novel intramembrane mechanism for the modulation of receptor tyrosine kinase activity.

[Multiple myeloma in siblings]

We encountered 2 patients with multiple myeloma in a family with 11 siblings, suggesting that the occurrence of the disease may be associated with genetic factors. Patient 1: The second daughter (age 79) was given a diagnosis of multiple myeloma and admitted to our hospital in December 1997 for treatment. IgG-lambda type M protein was detected by serum immunoelectrophoresis, punched out lesions (+) by X ray examination, and atypical plasma cells (14% of total) by bone marrow examination. Patient 2: The fifth daughter (age 68) received a diagnosis of multiple myeloma and was admitted to our hospital in May 1997 for treatment. Bence Jones-kappa type and IgA-kappa type M protein were detected by serum immunoelectrophoresis, punched out lesions (+) by X ray examination, and atypical plasma cells (90% of total) by bone marrow examination. It was noted that the sixth daughter had leukemia; hence, 3 of the 11 siblings had blood disorders. For this reason, HLA studies were performed and detected A31, B39, B51, and Cw7 in patient 1 and A31, B51, B62, and Cw4 in patient 2. Further case studies will hopefully reveal more details concerning the relationship between myeloma and HLA.