Establishment of a rat thyroid carcinoma cell line in vitro demonstrating high DNA synthesis in response to insulin-like growth factor I

We previously established transplantable rat thyroid carcinoma cell lines in vivo from primary thyroid tumors induced by N-bis-(2-hydroxypropyl)nitrosamine (DHPN). In the present study, an insulin-like growth factor I (IGF-I)-responsive cell line (TRTC-G1-C-A4) in culture was derived from one (well differentiated papillary type) of these carcinoma cell lines G1. TRTC-G1-C-A4 cells were found to exhibit specific saturable binding of IGF-I with a Kd of 1.16 nM at approximately 43.6 fmol/10(5) cells. Inclusion of IGF-I (10 and 50 ng/ml) in the culture medium resulted in a significant increase of [3H]thymidine incorporation and marked cell proliferation. IGF-II (10 ng/ml) and insulin (1 microgram) produced no such effects. The molecular weight of IGF-I receptors on the cell membrane was determined by Western blotting analysis, a single band of binding proteins with a molecular weight of 125 kDa being evident under non-reducing conditions. Reverse transcriptase polymerase chain reaction (RT-PCR) showed that the TRTC-G1-C-A4 cells contained IGF-I receptor mRNA with a sequence corresponding to that determined from rat uterus. These results demonstrate that the IGF-I receptor can be expressed in a thyroid carcinoma with an important contribution to cell growth.

Activation of human plasma cholesteryl ester transfer protein by human apolipoprotein A-IV

Function of apolipoprotein (apo) A-IV was studied for its role in cholesteryl ester transfer protein (CETP; lipid transfer protein, LTP) reaction between lipid microemulsions having the diameter of low density lipoprotein, being compared to apoA-I. CETP hardly catalyzed lipid transfer without apolipoproteins. ApoA-IV bound to the surface of the microemulsion in equilibrium with a similar affinity to that of other helical apolipoproteins, and activated the transfer reaction by CETP of cholesteryl ester, triacylglycerol and phosphatidylcholine between the emulsions. The rate of the transfer reaction of cholesteryl ester and triacylglycerol was directly proportional to the amount of the bound apoA-IV to the surface of the emulsion. For phosphatidylcholine, activation was less effective until 40% of total binding capacity of lipid emulsion was occupied by the apolipoprotein. Cholesteryl ester was highly preferred by CETP over triacylglycerol when equal amount of these lipids was present in the core of the apoA-IV-activated emulsion, resulting in almost no triacylglycerol transfer. However, when the emulsion has the core exclusively of triacylglycerol, triacylglycerol was transferred by CETP with the rate in the same order as that of cholesteryl ester transfer. These findings were all comparable to the results with apoA-I, and also consistent with our previous observation for other amphiphilic helical apolipoproteins such as apoA-II, E and C-III.

Lack of p16/CDKN2 alterations in thyroid carcinomas

Exons 1-3 of the p16/CDKN2 gene and exons 4-9 of the p53 gene were screened for mutations by single-strand conformation polymorphism (SSCP) analysis and direct sequencing of PCR-amplified DNA from human primary thyroid carcinomas and thyroid carcinoma cell lines. The samples included 21 papillary carcinomas, 2 undifferentiated carcinomas, 1 follicular carcinoma, 1 medullary carcinoma and 2 cell lines originating from thyroid undifferentiated carcinomas. No homozygous deletions and mutations in the p16/CDKN2 were observed in any of the primary tumors or cell lined. In contrast, one of the two undifferentiated carcinomas an both cell lines demonstrated point mutations in the p53 gene. These results that p16/CDKN2 gene alteration is not required for malignant transformation in the thyroid, while p53 gene mutations may play a role in the progression from differentiated to undifferentiated carcinoma.

Gene expression of neural cell adhesion molecule L1 in malignant gliomas and biological significance of L1 in glioma invasion

Neural cell adhesion molecule L1 is a member of the immunoglobulin superfamily that is expressed in the nervous system. Its functions have been mainly studied in vitro using premature neuronal cells. We show that all glioma cells tested, as well as normal glia cells, express a short type of L1, L1cs mRNA. The expression of L1 protein in glioma cells was confirmed by Western blotting and flow cytometric analysis. Migration assay showed that C6 glioma cells were stimulated to migrate to soluble L1 and L1cs released from L1- or L1cs-transfected fibroblast cells. The L1-stimulated migration was significantly inhibited by antibody that recognizes the immunoglobulin C2-like domain of L1. However, antibodies that recognize the fibronectin type III-like domain and the cytoplasmic (IC) domain of L1 had no effect on migration. Our in vivo migration study demonstrated the migration of L1 on C6 glioma cells that had been transfected in rat brains. These results suggest that L1cs expressed on glioma cells may play an important role in the adhesion and migration of glioma cells by homophilic binding (probably through the extracellular immunoglobulin C2 domain of L1) and that L1cs participates in tumor invasion along neuronal fibers.

Expression and characterization of the flavoprotein subcomplex composed of 50-kDa (NQO1) and 25-kDa (NQO2) subunits of the proton-translocating NADH-quinone oxidoreductase of Paracoccus denitrificans

This study reports the expression of the flavoprotein (FP) subcomplex of the proton-translocating NADH-quinone oxidoreductase (NDH-1) from Paracoccus denitrificans, which is composed of the NQO1 (50 kDa) and the NQO2 (25 kDa) subunits. The two subunits are co-expressed in Escherichia coli using a double expression plasmid system. The expressed subunits form a water-soluble heterodimer complex with 1:1 stoichiometry. The expressed complex contained one [2Fe 2S] cluster but almost no FMN or [4Fe 4S] cluster. The two latter prosthetic groups could be partially reconstituted with FMN, Na2S, and (NH4)2Fe(SO4)2 in vitro under anaerobic conditions. The reconstituted FP subcomplex showed EPR signals from two distinct species of iron-sulfur cluster. One resonance transition originates from a [2Fe-2S] cluster with g values of gx,y,z = 1.92, 1.95, and 2.00 and slow spin relaxation, which was tentatively assigned to the cluster N1a. These EPR properties are very similar to those reported for the NQO2 subunit expressed alone (Yano, T., Sled', V. D., Ohnishi, T., and Yagi, T. (1994) Biochemistry 33, 494-499). The other originates from a [4Fe 4S] cluster with g values of gx,y, z = 1.87, 1.94, and 2.04 and fast relaxing behavior, which are reminiscent of the cluster N3 in the membrane bound enzyme complex. After reconstitution with FMN, the FP subcomplex catalyzed electron transfer from NADH and from deamino-NADH to a variety of electron acceptors. The enzymatic properties of the FP subcomplex, reconstituted with FMN and iron-sulfur, correspond to those of the isolated P. denitrificans NADH-dehydrogenase complex.

Expression and secretion of rabbit plasma cholesteryl ester transfer protein by Pichia pastoris

The rabbit cholesteryl ester transfer protein (CETP) was expressed in the methylotrophic yeast Pichia pastoris by introducing the CETP cDNA under the control of the methanol-inducible alcohol oxidase promoter. The cDNA was cloned from in vitro amplified cDNA of rabbit liver mRNA. The nucleotide sequence of the cloned cDNA differed slightly from the previously published sequence that changed the amino acid sequence in six residues. Interestingly, five of these replacements are identical to the corresponding residues in human CEPT. In addition, the encoded mature N-terminal sequence was changed from Cys- to Arg-Glu-Phe- to link the CETP sequence to the yeast acid phosphatase signal peptide. The culture medium of the transformed cells induced with 1% methanol contained both cholesteryl ester and triglyceride transfer activity comparable to that of rabbit plasma. Like rabbit plasma, the lipid transfer activity in the medium could be inhibited by monoclonal antibodies that block CE/TG transfer or TG transfer alone. Immunoblot analysis of M(r) = 80 K and minor species of M(r) = 60-100 K. In spite of these differences, the specific transfer activity of the recombinant CETP was indistinguishable from that of rabbit plasma CETP of M(r) = 74 K. N-Glycosidase F treatment converted both the recombinant and plasma CETP to a single species of M(r) = 55 K. Both the plasma and recombinant CETP lost their activity after removal of N-linked carbohydrate and sialic acid. A single 55 K component was found in the cell-lysates. The intracellular form of the recombinant CETP was not modified by N-glycosidase F treatment. In conclusion, the recombinant CETP is synthesized as an inactive polypeptide that is processed and secreted as a functional glycoprotein. In addition, the N-terminal Cys residue of the plasma CETP is not required for its activity.

Experimental hepatitis induced by Campylobacter jejuni infection in Japanese quail (Coturnix coturnix japonica)

To establish an experimental model for vibrionic hepatitis caused by Campylobacter jejuni, Japanese quails (Coturnix coturnix japonica) were inoculated with C. jejuni strains isolated from chicken hepatitis (BL107) and human diarrhea (HP5113). Necrotic liver lesions were formed by intra-pancreaticoduodenal vein injection by which the bacteria reached the liver directly via the portal vein, but not by intra-gastric infection. These liver lesions were observed from day 1 to 7 after the infection. The pathological changes were weak and no clinical signs were observed throughout the experimental period. By immunohistochemistry, the bacterial antigens were detected in the hepatocytes, and intercellular spaces between the hepatocytes, and in the macrophages during the early stage of the infection. When focal hepatocyte necrosis was formed, the antigen was detected more frequently in the intact hepatocytes at the periphery of the lesions than within necrotic foci. The bacteria were not detected from the liver, spleen or blood according to raising the serum agglutination titer. In contrast, the bacteria immediately invaded the bile in 5 min post-infection and were retained in the gallbladder for long periods. The present study showed that necrotizing hepatitis was formed by intra-pancreaticoduodenal vein infection of the quail with C. jejuni.

G --> A mutation of ras genes and infrequent p53 gene mutation in rat transplantable thyroid carcinoma lines from tumors induced in vivo by N-bis(2-hydroxypropyl)nitrosamine

In a comparative study, we have investigated mutational activation of three kinds of ras genes and the p53 gene (exons 5-8) in 19 rat transplantable thyroid carcinoma lines derived from in vivo tumors induced by DHPN. Mutations were identified using single-strand conformation polymorphism and DNA sequencing analysis, and activated ras oncogenes were detected in 6 lines (31%). These all had mutations in Ki-ras codons at 12 or 63, and one of them also possessed a Ha-ras mutation at codon 12 as a double mutation. Three mutations of Ki-ras at codon 12 involved the second nucleotide and two the first position, the other being found at the first nucleotide in codon 63. Base alterations of p53 gene were found in two lines. One had an insertion of 1 base (thymine) between codon 206 and codon 207. Historically, it was diagnosed as a poorly differentiated papillary carcinoma (scirrhous pattern). In the another case, there was no amino acid change although one base substitution occurred at codon 283 (GAG --> GAA) of exon 8. These results indicate that, in the ras family, DHPN induces Ki-ras gene activation preferentially and that p53 mutation may be infrequent in thyroid carcinogenesis in rats, our data thus corresponding well with the previous reports that an inactivated p53 gene only plays a major role in human undifferentiated thyroid carcinomas.

Abrogation of lung metastasis of human fibrosarcoma cells by ribozyme-mediated suppression of integrin alpha6 subunit expression

The interaction of tumor cells with the basement membrane plays a crucial role in tumor metastasis. VLA-6 (alpha6beta1) integrin is one of the major surface receptors for the basement membrane, specifically recognizing laminin. To study the role of VLA-6 integrin in tumor invasion and metastasis, we synthesized a ribozyme that selectively degrades the integrin alpha6 subunit mRNA. The catalytic activity of the ribozyme was verified by in vitro cleavage of alpha6 subunit mRNA. Introduction of the anti-alpha6 ribozyme gene into the human fibrosarcoma cell line HT1080 yielded stable transfectants, which expressed a significantly reduced level of integrin alpha6 mRNA. Flow cytometric analysis showed that the surface expression of VLA-6, but not other integrins, was reduced by approximately 70% in transfected cells. Ribozyme-transfected cells were less adherent to laminin-coated substrata and less invasive into reconstituted basement membrane than mock-transfected cells. When injected i.v. into nude mice, ribozyme-transfected cells produced no lung metastasis in all except 1 of 35 mice, though mock-transfected cells produced multiple lung metastases in 22 of 29 mice. Our results indicate that VLA-6 integrin plays a critical role in tumor invasion and metastasis and may serve as a potential target for eradication of tumor metastasis in the lung.

Tl-201 SPECT in Kimura's disease involving the parotid glands and cervical nodes

Kimura's disease is a chronic inflammatory condition producing subcutaneous tumor-like nodules, mainly in the head and neck region. Most patients have involvement of regional lymph nodes and major salivary glands. The authors present two cases of Kimura's disease with parotid gland and postauricular lymph node involvement. With Tl-201 SPECT, elevated uptake was noted on early and delayed images. Kimura's disease should be included in the differential diagnosis when increased Tl-201 uptake in head and neck mass lesions is noted.

201TL SPECT for evaluating head and neck cancer

BACKGROUND

Thallium-201 (201Tl) has come to be widely used in diagnosis of several kinds of malignant tumor, but its usefulness in diagnosing head and neck cancer has not been established.

PURPOSE

This study investigated the usefulness of 201Tl SPECT imaging in patients with head and neck cancer histologically confirmed.

METHODS

Eighteen patients with histologically proven head and neck cancer were studied. 201Tl SPECT images were obtained both 15 min and 4 hours after intravenous injection of 148 MBq of 201Tl-chloride. 201Tl-indices were calculated semiquantitatively to assess the tracer uptake in relation to tumor size and histological type.

RESULTS

High 201Tl uptake was noted in all primary tumors and metastatic lymph nodes on the both early and delayed images, but 201Tl-indices did not show any correlation with tumor size or histological type.

CONCLUSION

Primary had and neck cancer and lymph node metastasis can be effectively visualized with 201Tl SPECT. It may provide information in addition to morphological changes and may be supplemental method to use in the evaluation of head and neck cancer.

Detection of serum-dependent cytotoxic activity of Campylobacter jejuni and its characteristics

We previously set forth appropriate three assay systems using Chinese hamster ovary cells to detect the Campylobacter jejuni cytotoxin. Although we could not reach a conclusion because the cytotoxins shown in this study were not purified, at least three different cytotoxins were detected in these assay systems. The first cytotoxin in the presence of fetal calf serum (FCS) was heat-labile and the molecular weight (Mw) was estimated at 50-100 k by ultrafiltration. The second cytotoxin detected in the presence of newborn calf serum (NCS) was heat-stable and Mw was estimated at 0.5-3.0 k. The third cytotoxin detected in serum-free culture (SFC) assay was heat-labile and non dialyzable. However, Mw was not estimated since the low Mw and heat-stable cytotoxin was also detected in this assay. The cytotoxic activity detected in FCS and NCS assays, but not that detected in SFC assay, was completely abolished by treatment with a reducing agent. In contrast, the cytotoxicity detected in both FCS and NCS assays was not inactivated by such an enzyme as trypsin, lipase, neuraminidase, and beta-galactosidase. When the filtrate was heated at 100 degrees C to inactivate the heat-labile cytotoxin, the cytotoxic activity was detected in the NCS assay but not in FCS assay. However, when NCS was added to this heated filtrate, the cytotoxicity was restored in FCS assay. Furthermore, when normal rabbit serum (NRS) was added, no cytotoxicity was restored. The cytotoxic activity in SFC assay was completely inactivated with FCS or NRS. These findings suggest that the cytotoxic activity is dependent on serum added to tissue culture medium and that the substance amplifying and/or inhibiting the cytotoxic activity may be present in serum.

Haloperidol inhibits neuronal nitric oxide synthase activity by preventing electron transfer

The effect of a neuroleptic, haloperidol (HP), on nitric oxide formation catalyzed by neuronal nitric oxide synthase (n-NOS) in the porcine brain was investigated. HP inhibited n-NOS activity noncompetitively versus L-arginine as a substrate, decreasing the maximal velocity (Ki value for HP = 31 microM). HP also inhibited the CaM-dependent NADPH consumption by n-NOS (IC50 = 221 microM). These data demonstrate the possibility that HP may mediate some neuronal functions through inhibiting NO release by preventing either the electron transfer through n-NOS or the formation of the activated reduced species of oxygen necessary for the formation of citrulline. And an interaction of HP with CaM may possibly affect the consumption of NADPH and n-NOS enzyme activity.

Generation of reactive oxygen species during the enzymatic oxidation of polycyclic aromatic hydrocarbon trans-dihydrodiols catalyzed by dihydrodiol dehydrogenase

Dihydrodiol dehydrogenase (DD; EC 1.3.1.20) catalyzes the oxidation of polycyclic aromatic hydrocarbon (PAH) trans-dihydrodiols (proximate carcinogens) to catechols which rapidly autoxidize to yield o-quinones (Smithgall, T. E., Harvey, R. G., and Penning, T. M. (1988) J. Biol. Chem 263, 1814-1820). Although this pathway suppresses the formation of the PAH anti- and syn-diol epoxides (ultimate carcinogens), the process of autoxidation is anticipated to yield reactive oxygen species (ROS). We now show that the NADP+ dependent oxidation of (+/-)-trans-1,2-dihydroxy-1,2-dihydronaphthalene (Npdiol) and (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (Bpdiol) catalyzed by homogeneous DD is accompanied by the consumption of molecular oxygen and the production of H2O2. With both trans-dihydrodiol substrates, oxygen consumption was stoichiometric with H2O2 production consistent with the reaction: QH2 + O2 = H2O2 + Q, where QH2 is the catechol and Q is the o-quinone. Using Npdiol or Bpdiol as substrates, a burst of superoxide anion production is catalyzed by DD which can be detected as the rate of cyt c reduction that is inhibited by superoxide dismutase. Using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as spin-trapping agent, secondary spin adducts corresponding to DMPO-CH3 were formed during the enzymatic oxidation of Npdiol and Bpdiol. The formation of the CH3. radical arises from the OH. attack of DMSO, which was used as cosolvent. These spin adducts were attenuated by superoxide dismutase and catalase, implying that O2-. and H2O2 are obligatory for the formation of DMPO-CH3. It is proposed that O2-. is the radical that propagates autoxidation and that the resultant H2O2 undergoes Fenton chemistry to produce the OH. radical. Identical spin adducts were observed using a superoxide anion generating system (hypoxanthine/xanthine oxidase) and DMPO as spin-trapping agent in the presence of DMSO. The ability of DD to generate ROS during the oxidation of PAH trans-dihydrodiols (proximate carcinogens) may have important implications for tumor initiation and promotion.

Cerebral perfusion imaging evaluates pharmacologic treatment of unilateral moyamoya disease

Unilateral Moyamoya disease presents as unilateral stenosis or obstruction of the supraclinoid internal carotid artery, which causes cerebral hypoperfusion resulting in seizures or TIA-like attacks. In severe cases, surgical treatment is performed with superficial temporal artery-middle cerebral artery anastomosis. In mild cases, conservative management is the treatment of choice. Flunarizine is a calcium ion anti-blocking agent, whose primary effect is that the cerebral vessels have been used for the treatment of postcerebrovascular disorders. Recently, it has been suggested that flunarizine could be used to treat Moyamoya disease. This report documents the efficacy of flunarizine to improve regional cerebral perfusion in Moyamoya disease.

The correlation of Ki-67 staining indices with tumour doubling times in regrowing non-functioning pituitary adenomas

In order to improve our ability to predict the regrowth of nonfunctioning pituitary adenomas, we tried to assess the correlation between growth fractions with Ki-67 and PCNA (proliferating cell nuclear antigen) and tumour doubling times in regrowing tumours, and also to find out any difference of growth fractions between the regrowing and the cured cases. In 33 patients with non-functioning pituitary adenomas, 14 cases including 11 with cavernous sinus invasion showed residual tumour on MRI after the operation (regrowing group) and 19 cases had no tumour regrowth on MRI within 5 years after the operation (cured group). Immunocytochemical studies were done with monoclonal antibodies (anti-PCNA, anti-Ki-67: MIB-1). The growth fraction of each tumour was estimated by calculating the ratio of the positive nuclei to the total number of tumour cells with the aid of an image analyser (Mac SCOPE). The tumour doubling times were estimated from serial CT or MRI with the aid of the image analyser (NIH image). Ki-67 staining indices ranged from 0.2% to 1.5% (n = 14, 0.86 +/- 0.10%; mean +/- SEM) in the regrowing group, and from 0.1% to 0.5% (n = 19, 0.23 +/- 0.03%) in the cured group. PCNA staining indices of the regrowing group ranged from 0.6% to 24% (n = 14, 3.7 +/- 1.6%). In the regrowing group, the tumour doubling times ranged from 200 to 2550 days (930 +/- 180 days), and showed a significant inverse correlation with Ki-67 staining indices, but no correlation with PCNA staining indices. The regrowing group showed a significantly higher Ki-67 staining index (n = 14, 0.86 +/- 0.10%) than the cured group (n = 19, 0.23 +/- 0.03%) (p < 0.01). These results indicate that immunocytochemical studies using MIB-1 may be better than those with PCNA for the prediction of regrowth in non-functioning pituitary adenomas. Immunocytochemical study with MIB-1 could lead to the accurate prediction of the rapid regrowing lesions in non-functioning adenomas.

Evidence for the presence of an inactive precursor of human hepatocyte growth factor in plasma and sera of patients with liver diseases

Human hepatocyte growth factor (hHGF), which is now known to be the same protein as the scatter factor and the tumor cytotoxic factor, is a heterodimeric protein with one heavy chain and one light chain linked together by a disulfide bond, and is thought to be involved in liver regeneration. Using an enzyme-linked immunosorbent assay (ELISA) and Western blot analysis, we found that a significant amount of single chain precursor of hHGF (pro-hHGF) was present in plasma of patients with fulminant hepatic failure (FHF) and that normal human serum contained a protease or proteases that convert pro-HGF to a heterodimeric (mature) form of hHGF. We also showed that the processing protease activity for hHGF was suppressed by such serine protease inhibitors as leupeptin, antipain, and aprotinin, and that sera of patients with liver diseases such as fulminant hepatic failure, acute hepatitis, chronic hepatitis, and cirrhosis contained not only pro-hHGF but also the protease. This is the first report showing the presence of pro-hHGF in human blood, and our observations suggest that hHGF is synthesized and secreted from the hHGF-producing cells as an inactive pro-hHGF after hepatic injuries, and the pro-hHGF is then converted to an active heterodimeric form of hHGF in the blood. It is also suggested that plasma of patients with liver diseases contains an active protease or proteases that convert pro-hHGF to a mature form of hHGF.

Homozygous deletions of p16INK4A/MTS1 and p15INK4B/MTS2 genes in glioma cells and primary glioma tissues

The p16INK4A/MTS1 (p16) and p15INK4B/MTS2 (p15) genes map to 9p21 where genetic alterations have been frequently reported in various human tumors. Using the polymerase chain reaction (PCR), we investigated the loss of these genes on primary glioma samples and cultured glioma cells. All or any of three exons of the p16 gene were homozygously delted in 11 (35.5%) of 31 glioblastomas, none of 9 anaplastic astrocytomas and 5 astrocytomas, and in all 6 human glioma cell lines. Exon 2 of the p15 gene was homozygously deleted in 4 (12.9%) of 31 glioblastomas, but not in lower grade gliomas. It was homozygously deleted in 5 (83.3%) of 6 glioma cell lines. In 12 short-term cultures of cells derived from primary glioma samples, 5 (41.7%) and 2 (16.7%) glioblastoma-derived cells had homozygous deletion of all or any of the three exons of the p16 gene and exon 2 of the p15 gene, respectively. The deletion pattern of these genes in cultured cells was completely consistent with that seen in the primary tumors. Furthermore, two long-term cultures retained both genes that were identical to those in the original tumor tissues. Our results indicate that loss of the p16 and p15 genes may be involved in tumor progression in human gliomas, especially in the development of glioblastoma, that this loss may give growth advantage to the cells in culture, and that it is not the result of culture artifacts.

Cloning of a cDNA encoding a 190-kDa insulin receptor substrate-1-like protein of simian COS cells

Major insulin signals such as stimulation of glucose uptake and DNA synthesis and modification of hexose metabolism are mediated by the tyrosine-phosphorylated insulin receptor substrate-1 (IRS-1; pp180) in many species of cells. We cloned cDNA encoding a 190-kDa IRS-1-like protein (pp190) in simian COS cells and which is slightly larger than IRS-1 (pp180) of human, rat, and mouse cells. The deduced amino acid sequence of COS pp190 consisted of 1251 amino acids and was 96.4%, 87.9% and 88.7% identical to human, mouse and rat IRS-1. The COS pp190 bound to SH2 (src-homology 2) domains of p85, Grb2/Ash, and SH-PTP2, as did IRS-1. In IRS-1-knockout mice, insulin signals are thought to be mediated by IRS-2 (pp190), which is an alternative signaling molecule and is slightly larger than IRS-1. However, the COS pp190 may be a simian homologue of IRS-1, but not of IRS-2. The results of Southern blotting suggested the possibility that Chinese hamster ovary (CHO) cells have not only the IRS-1 gene but also a gene related to the COS pp190.

[Clinical utility of DNA fingerprinting by arbitrarily-primed polymerase chain reaction (AP-PCR) in nosocomial infection caused by methicillin-resistant Staphylococcus aureus]

Recently, nosocomial outbreaks of MRSA have become an serious social problem in Japan. To examine the routes of transmission of MRSA, the establishment of an accurate MRSA typing system is essential. Previously, we reported that the DNA fingerprinting by AP-PCR might be a useful method to differentiate MRSA strains. In this study, we tried to investigate the clinical usefulness of DNA fingerprinting by AP-PCR using clinically-isolated MRSA strains. Twenty-four MRSA strains (12 with coagulase type IV, and 12 with coagulase type II) isolated from patients in our department were used. Other typing methods (the sensitivity of antibiotics, pulsed-field gel electrophoresis, and plasmid analysis) were also performed. As a result, the typing pattern by AP-PCR correlated well with other typing methods. MRSA strains with coagulase type IV showed almost the same pattern, suggesting that these strains were nosocomially transmitted. On the other hand, MRSA strains with coagulase type II showed various patterns, suggesting these strains were not nosocomially transmitted. In conclusion, the typing by AP-PCR seemed to be a useful tool evaluate a nosocomial MRSA transmission.

Cytotoxin detection in Campylobacter jejuni strains of human and animal origin with three tissue culture assay systems

Cytotoxin (CTX) production in 34 human and 22 animal strains of Campylobacter jejuni isolated in Japan and other countries was studied by three assay systems described previously. Furthermore, cholera-like enterotoxin production by these strains was tested by reversed passive latex agglutination (RPLA). CTX titres in the fetal calf serum (FCS) and newborn calf serum (NCS) assays were relatively lower, with a maximum of 4 and 8, respectively, than the maximum of 128 for the serum-free culture (SFC) assay. CTX detection rates were 62, 85 and 100% in human isolates and 64, 77 and 100% in animal isolates for the FCS, NCS and SFC assay systems, respectively. There was no significant difference in the detection rate of CTX between human and animal isolates, or between human isolates from Japan and other countries. With the three assay systems, the strains were divided into four groups from the pattern of CTX detection; 54% of strains gave positive results in all three assay systems, and 9% of them were positive in the SFC assay only. Morphological changes on CHO cells showed distended instead of rounded cells with eight of 21 strains negative in the FCS assay. Cholera-like enterotoxin was not detected in the culture filtrate of any of the strains when tested by RPLA. These results indicate that cytotoxin production by C. jejuni is complex as compared with that of other enteric pathogens.

Three-dimensional imaging of nitric oxide production in the rat brain subjected to ischemia-hypoxia

By the systemic administration of diethyldithiocarbamate and iron into the rat, nitric oxide radicals produced in the brain during ischemia-hypoxia were trapped. The right hemisphere of the brain was then removed and frozen with liquid nitrogen. With use of recently developed electron paramagnetic resonance imaging instrumentation and techniques, three-dimensional imaging of the production of the nitric oxide radicals in several brains was performed. The results suggest that nitric oxide radicals were produced and trapped in the areas that are known to have high nitric oxide synthase activity, such as cortex, hippocampus, hypothalamus, amygdala, and substantia nigra. In this ischemia-hypoxia model, which did not interrupt the posterior circulation, the production and trapping of nitric oxide in the cerebellum were approximately 30% of those in the cerebrum.

Allergen challenge in asthma: association of eosinophils and lymphocytes with interleukin-5

To test whether eosinophil recruitment after pulmonary allergen challenge is associated with interleukin (IL)-5 in patients with asthma, we performed segmental bronchoprovocation (SBP) with saline, and with low and high dosages of ragweed extract in six patients with allergic asthma. Bronchoalveolar lavage (BAL) of the challenged segments was performed 5 min after challenge (immediate BAL fluid) and repeated 24 h later (late BAL fluid). Allergen challenge resulted in recruitment of eosinophils, and increased levels of eosinophil-active cytokines. A bioassay showed the predominant eosinophil-active cytokine in the late BAL fluids to be IL-5. Analysis of the late BAL fluids revealed that IL-5 levels correlated with the numbers of eosinophils and lymphocytes. This study provides evidence that IL-5 is a critical cytokine associated with eosinophil and lymphocyte recruitment into the airways of patients with asthma following exposure to allergen.