Accelerated echo-planar J-resolved spectroscopic imaging in the human brain using compressed sensing: a pilot validation in obstructive sleep apnea.

BACKGROUND AND PURPOSE: Echo-planar J-resolved spectroscopic imaging is a fast spectroscopic technique to record the biochemical information in multiple regions of the brain, but for clinical applications, time is still a constraint. Investigations of neural injury in obstructive sleep apnea have revealed structural changes in the brain, but determining the neurochemical changes requires more detailed measurements across multiple brain regions, demonstrating a need for faster echo-planar J-resolved spectroscopic imaging. Hence, we have extended the compressed sensing reconstruction of prospectively undersampled 4D echo-planar J-resolved spectroscopic imaging to investigate metabolic changes in multiple brain locations of patients with obstructive sleep apnea and healthy controls. MATERIALS AND METHODS: Nonuniform undersampling was imposed along 1 spatial and 1 spectral dimension of 4D echo-planar J-resolved spectroscopic imaging, and test-retest reliability of the compressed sensing reconstruction of the nonuniform undersampling data was tested by using a brain phantom. In addition, 9 patients with obstructive sleep apnea and 11 healthy controls were investigated by using a 3T MR imaging/MR spectroscopy scanner. RESULTS: Significantly reduced metabolite differences were observed between patients with obstructive sleep apnea and healthy controls in multiple brain regions: NAA/Cr in the left hippocampus; total Cho/Cr and Glx/Cr in the right hippocampus; total NAA/Cr, taurine/Cr, scyllo-Inositol/Cr, phosphocholine/Cr, and total Cho/Cr in the occipital gray matter; total NAA/Cr and NAA/Cr in the medial frontal white matter; and taurine/Cr and total Cho/Cr in the left frontal white matter regions. CONCLUSIONS: The 4D echo-planar J-resolved spectroscopic imaging technique using the nonuniform undersampling-based acquisition and compressed sensing reconstruction in patients with obstructive sleep apnea and healthy brain is feasible in a clinically suitable time. In addition to brain metabolite changes previously reported by 1D MR spectroscopy, our results show changes of additional metabolites in patients with obstructive sleep apnea compared with healthy controls.

Expression of interleukin-18 and its receptor in mouse ovary.

PROBLEM: Interleukin-18 (IL-18) strongly induces interferon-gamma production and is produced not only by types of immune cells but also by types of non-immune cells. Ovulation is thought to be an inflammation-like reaction in which many pro-inflammatory cytokines are involved. We investigated whether IL-18 is involved in the functions of ovary. METHOD OF STUDY: The 4-week-old immature female mice were examined for IL-18 and IL-18 receptor (IL-18R) expression on their ovaries under stimulation with pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) by immunohistochemical staining, Western blotting and reverse transcript-polymerase chain reaction. The IL-18R was blocked by the injection of anti-IL-18R monoclonal antibody to immature mice during PMSG-hCG stimulation, and the number of ovulated ova was counted. RESULTS: The expression of both proteins and mRNA of IL-18 and IL-18R were very low in immature ovaries before stimulation, but after PMSG injection both IL-18 and IL-18R increased dramatically in theca cells and reached a maximum level at the peri-ovulatory phase then slightly lowered, but still kept a high level during the luteal phase in the corpus luteum. The treatment of IL-18R monoclonal antibody to the mice during ovarian stimulation reduced the number of ovulated ova and inhibited the expansion of cumulus cells surrounding the ovum. CONCLUSION: IL-18 and IL-18R play roles in various kinds of function of ovary.

HVJ-liposome-mediated transfection of HSVtk gene driven by AFP promoter inhibits hepatic tumor growth of hepatocellular carcinoma in SCID mice.

Suicide gene therapy using ganciclovir (GCV) with transfection of the herpes thymidine kinase (HSVtk) gene has been studied for cancer therapy. The present study demonstrates an efficient method of suicide gene therapy for multiple hepatic tumors, involving repetitive transfection of the HSVtk gene driven by the alpha-fetoprotein (AFP) promoter using hemagglutinating virus of Japan (HVJ)-liposomes. AFP-producing cells (HUH7) and AFP-nonproducing cells (LS180) were injected subcutaneously (s.c.) to establish tumors in nude mice. Two plasmid constructs, bacterial LacZ gene driven by the AFP promoter (AFPLacZ), and HSVtk gene driven by the AFP promoter (AFPTK1) were encapsulated into the HVJ-liposome and used. When AFPLacZ was injected into the s.c. tumors, expression of LacZ gene was confined to HUH7 tumors. Repeated transfection of AFPTK1 followed by GCV treatment markedly suppressed growth of HUH7 tumors, and apoptosis of HUH7 cells was recognized in the tumor. Next, HUH7 cells were injected into the portal vein in severe combined immunodeficiency mice to establish a hepatic tumor model. After inoculation with the tumor, HVJ-liposomes containing the AFPTK1 plasmid vector were injected into the portal vein via the splenic hilum, followed by GCV treatment. This gene therapy significantly inhibited the growth of tumors in the liver and markedly improved survival. Three injections of the AFPTK1 plasmid vector completely inhibited tumor growth. This procedure seems to have great potential for the treatment of multiple hepatic tumors.

Overexpression of SCC antigen and cyclins in an adenoid squamous carcinoma cell line derived from the maxillary sinus.

Squamous cell carcinoma antigen (SCC-Ag) is produced by the two almost identical, tandemly arrayed genes, SCCA1 and SCCA2. In this study, we investigated the mechanism of increased expression of SCC-Ag in a cell line SCCMM derived from an aggressive adenoid SCC with high titer of SCC-Ag in the patient serum. The differential polymerase chain reaction using specific primers for SCCA1 and SCCA2 revealed no gene amplification in SCCMM. However, RT-PCR demonstrated that levels of SCCA1 and SCCA2 mRNAs in SCCMM were 80- and 120-fold higher than those in CaSki as a reference SCC cell, respectively. Western blot analysis showed that the levels of these two SCC-Ag proteins in SCCMM were 15-fold higher than those in CaSki, suggesting that expression of the SCC-Ag in SCCMM was controlled at both the transcriptional and post-transcriptional levels. To investigate highly malignant character of SCCMM, expression of cell cycle regulatory proteins was investigated by Western blotting. Cyclin E and cyclin B1 were expressed at approximately 100-fold higher levels in SCCMM than in CaSki, but Cip/Kip cyclin-dependent kinase inhibitors (CDKIs) were expressed at low levels and p16 and p19 ink4 CDKIs were not detected. These results suggest that the aggressive growth of SCCMM is due, at least in part, to large increases in cyclin E and cyclin B1 expression with low levels of CDKIs.

Dual antitumor effects of 5-fluorouracil on the cell cycle in colorectal carcinoma cells: a novel target mechanism concept for pharmacokinetic modulating chemotherapy.

5-Fluorouracil (5-FU) is one of the most widely used anticancer agents for advanced colorectal carcinoma, but its response rate is only 15%. The "pharmacokinetic modulating chemotherapy" (PMC) regimen that we have advocated has proved to be highly effective in treating colorectal carcinoma. PMC consists of a continuous i.v. infusion of 5-FU over 24 h for 1day a week at 600 mg/m2/day, and an oral dose of uracil-tegafur (UFT), a 5-FU derivative, at 400 mg/day for 5-7 days per week, repeated every week for more than 6 months. Assays of 5-FU in 23 patients receiving this treatment showed serum concentrations ranging from 88 to 1,323 ng/ml. We then analyzed the effects of clinically relevant concentrations of 5-FU found in colorectal cancer patients treated with the PMC regimen on the growth of three human colorectal adenocarcinoma cell lines, SW480 and COLO320DM (mutant p53) and HCT116 (wild-type p53). Exposure of these three cell lines to 5-FU resulted in growth inhibition in a dose-dependent manner. Exposure to 100 ng/ml of 5-FU in SW480 and COLO320DM caused G1 arrest after 24 h and G2 arrest after 72-144 h, and only a minority of the cell population showed apoptotic features, which indicated that most of the cells were killed through mitotic catastrophe, nonapoptotic cell death. On the contrary, exposure to 1000 ng/ml of 5-FU in SW480 and COLO320DM resulted in G1-S-phase arrest and the induction of apoptosis throughout the experimental period. Nuclear cyclin B1 expression was markedly induced with exposure to 100 ng/ml of 5-FU in SW480 and COLO320DM; and expression of 14-3-3sigma protein, a cell cycle inhibitor in the GG phase, was induced in SW480. ICT116 responded to lower concentrations of 5-FU more rapidly: G2 arrest was seen after 24-72 h of exposure to 10 ng/ml of 5-FU, and G,1rrest was seen after 12-24 h of exposure to 100 ng/ml. These results show that 5-FU acts via two different pathways, depending on dose: (a) G,1S-phase cell cycle arrest and apoptosis at 1,000 ng/ml in SW480 and COLO320DM, and 100 ng/ml in HCT116; and (b) G2-M-phase cell cycle arrest and mitotic catastrophe at 100 ng/ll in SW480 and COLO320DM, and 10 ng/ml in HCT116. These results suggest that the efficacy of our PMC regimen is based on targeting at least two different phases of the cell cycle. In our clinical trial, we showed efficacy independent of p53 status, ascertained by cell kinetic analysis in vitro, which may lead to a novel concept of schedule-oriented biochemical modulation of this drug.

Early detection of relapse and evaluation of treatment for mixed chimerism using fluorescence in situ hybridization following allogeneic hematopoietic cell transplant for hematological malignancies.

In order to detect chimerism, fluorescence in situ hybridization (FISH) and cytogenetic analyses were performed on bone marrow cells from 47 patients with hematological malignancies following allogeneic hematopoietic cell transplant (HCT). The dual-color XY, major Bcr-Abl (M-Bcr-Abl), and specific alpha-satellite probes were used for sex-mismatched HCT, chronic myeloid leukemia (CML), and myelodysplastic syndrome (MDS) cases with karyotypic abnormalities before HCT, respectively. Donor cells were found using FISH analysis in all 32 cases examined within 2 months following HCT, confirming engraftment. In six cases, however, cytogenetic analysis failed to detect donor cells due to lack of metaphases. Relapse occurred in four of the six cases in which mixed chimerism was detected using FISH analysis after 6 months of HCT. In contrast, after 12 months of HCT, no relapse was found in 24 patients without host cells. For two patients with mixed chimerism, gradual reduction of immunosuppressants or donor lymphocyte infusion resulted in the disappearance of host cells as analyzed using FISH analysis. In three extramedullary relapse cases, however, cytogenetic relapse preceded morphological and FISH relapse. These findings suggest that FISH analysis is more useful for detecting residual host cells after HCT, and the combination of FISH and cytogenetic analyses provide a more detailed evaluation for HCT patients. The results also indicate that monitoring of mixed chimerism using FISH analysis after 6 months of HCT is important for allowing the early detection of hematological relapse.

High frequency of tetraploidy detected in malignant melanoma of Japanese patients by fluorescence in situ hybridization.

Aneuploidy and hyperploidy are often detected in malignant melanoma by cytogenetic analysis and flow cytometric analysis of DNA content. To determine the ploidy of cells in surgical specimens of melanin-producing tumors of Japanese patients, we performed fluorescence in situ hybridization (FISH) using touch smear technique to count the number of chromosomes 18 and X + Y in interphase nuclei using alpha-satellite DNA probes, D18Z1, DXZ1 and DYZ3. A normal melanocyte strain showed two D18Z1 and two [DXZ1+DYZ3] signals per nucleus, indicating 2N, and a malignant melanoma cell line showed 4 per nucleus, indicating 4N, consistent with results of cytogenetic and flow cytometric analyses. Therefore we employed this FISH method to analyze ploidy of surgical specimens. Specimens obtained from 8 patients with nevus cell nevus showed 2 FISH signals per nucleus. On the other hand, in all specimens obtained from 8 patients with malignant melanoma (6 primary and 2 metastatic melanoma), 65-90% of cells exhibited 4 signals per nucleus, indicating 4N. Histopathologically, 50-70% of cells were identified as malignant melanoma cells, indicating that our FISH method is effective to detect melanoma cells in tissue. We also analyzed allelic loss of the p53 gene by FISH with a p53 locus-specific probe and mutation of the p53 gene by immunostaining since mutation and deletion of the p53 gene may cause hyperploidy. All specimens except one obtained from a case with young-onset metastatic melanoma exhibited no allelic losses or negative p53 staining, showing the p53 gene was intact. These results indicate that tetraploidy, not caused by p53 mutation or deletion, is commonly found in malignant melanoma of Japanese patients. It is also suggested that there is no positive relationship between tetraploidy and poorer prognosis, and mutation and allelic loss of the p53 gene might be markers of aggressive form of malignant melanoma.

Expression and role of p27(kip1) in neuronal differentiation of embryonal carcinoma cells.

We examined the expression and the regulation of p21(waf1) and p27(kip1) cdk inhibitors in P19 mouse embryonal carcinoma (EC) cells following treatment with all-trans retinoic acid (ATRA) to induce neuronal differentiation. The levels of p27 mRNA and protein increased within 24 h of treatment with ATRA, reaching a plateau 4-5 days later prior to neurite formation. In contrast, levels of p21 expression remained low until after neurites were extensively formed. Induction of muscle differentiation from P19 cells by treatment with dimethyl sulfoxide caused only transient increases in p27 levels. In a mutant P19 cell line, RAC65, treatment with ATRA induced neither p27 accumulation nor neuronal differentiation, but p21 mRNA expression increased markedly. In contrast, treatment of RAC65 cells with 9-cis retinoic acid induced both p27 expression and neuronal differentiation. Correlation between p27 expression and neuronal differentiation was also observed in NT2/D1 human EC cells. Luciferase reporter assays showed that p27 promoter activity increased in ATRA-treated cells, consistent with the elevation of p27 mRNA levels. Arrest of neuronal differentiation of P19 cells by okadaic acid resulted in inhibition of p27 expression, whereas p21 mRNA expression was greatly enhanced. Conversely, inhibition of p27 expression by antisense p27 oligonucleotides resulted in blockade of neuronal differentiation. Taken together, these results strongly suggest that the expression of p27 is indispensable for neuronal differentiation of EC cells.

Determination of the complete nucleotide sequence and haplotypes in the D-loop region of the mitochondrial genome in the oriental white stork, Ciconia boyciana.

The complete nucleotide sequence of the mitochondrial genome of the Oriental white stork, Ciconia boyciana, has been determined from captive storks by a novel method incorporating Long PCR and shotgun sequencing. 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes were identified as in other vertebrate mitochondrial genomes. The position and direction of the NADH6 and tRNA-Glu genes were the same as previously reported for avian mitochondrial genomes. A 71 bp direct repeat and long CAAA repeat sequences were found at the 3' end of the D-loop region, together with SCB-1, SCB-2, SCB-3, and three TAS sequences. Direct sequencing of the PCR fragments in the D-loop region in 26 captive Oriental white storks originating from Japan, China, and Russia revealed nucleotide differences at 18 sites along 1,248 bp, and a total of nine haplotypes have been identified. It was found that one pair of individuals in the Japanese captive breeding program were of the same haplotype, suggesting that they were caught from the same nest. The pair has since been dissolved in consideration of the possibility of inbreeding depression.

Association between mast cell chymase genotype and atopic eczema: comparison between patients with atopic eczema alone and those with atopic eczema and atopic respiratory disease.

BACKGROUND: It has remained unclear whether genetic background of patients with atopic eczema (AE) alone is identical to that of patients with both AE and atopic respiratory disease. OBJECTIVE: We aimed to assess whether there is a genetic difference between these two groups of AE patients. METHOD: We determined the genotype with regard to an allelic polymorphism in the gene for mast cell chymase (MCC; a serine protease secreted from mast cells) in 169 AE patients. RESULTS: MCC genotype was significantly associated with pure AE patients who did not have a predisposition to atopic respiratory disease and whose serum IgE concentration was < 500 IU/mL. The distribution of MCC genotypes also differed significantly between the latter patients and those AE patients with bronchial asthma and a serum IgE concentration of > 2000 IU/mL. CONCLUSION: These results suggest that pure AE is associated with genetic variants of MCC, and that the genetic basis of pure AE differs from that of AE associated with atopic asthma.

Molecular and clinical study of familial adenomatous polyposis for genetic testing and management.

Familial adenomatous polyposis (FAP) is an inherited predisposition to colorectal cancer characterized by the development of numerous adenomatous polyps, predominantly in the colorectal region. Germline mutations of the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis. We examined germline mutations of the APC gene and clinical features among eighty-seven individuals who consisted of thirty-nine FAP-patients, thirty-seven of their family members with a 1 in 2 risk of predisposition to this disease, and eleven normal persons. We accurately identified nine heterozygotes, among individuals with a 1 in 2 risk by genetic testing, without the uncertainty of the recurrence risk calculated by Bayes' theorem. Six of the nine heterozygotes were confirmed to have colorectal polyps by colonoscopic examination. Since they were diagnosed at 12.7 years-of-age on average, and were no more than 20 years old, they could be treated to prevent colorectal cancer. Based on the genotype-phenotype correlation, we concluded that the germline mutations responsible for the sparse polyps phenotype of FAP-patients tend to locate from codon 1055 in the proximal region of the APC gene, while those for the profuse type locate from codon 1102 in the distal region. Among the thirty-nine FAP-patients, we found that those with the germline mutations within codon 1055 and codon 1262 had colorectal carcinomas of an advanced stage, at a high rate (71.4%). Special attention and aggressive intervention is needed in these patients and relatives at risk. With reasonable and appropriate management, it should be possible to prolong and improve the quality of life of those family members both affected and at risk.

Hepatocyte growth factor promotes migration of human hepatocellular carcinoma via phosphatidylinositol 3-kinase.

Hepatocyte growth factor (HGF) is known to be a potent mitogen and motogen for epithelial cells. Hepatocellular carcinoma (HCC) often metastasizes, and the c-Met/HGF receptor is highly expressed by HCC cells. The aim of this study was to investigate the signaling pathways associated with the motogenic effect of HGF on HCC cells via c-Met. HCC cell lines (Hep3B, HepG2, PLC, and Huh-7) and HCC cells harvested from patients were used for the Boyden chamber assay of chemotactic activity as well as for immunoprecipitation and immunoblotting studies. HGF stimulated the motility of Hep3B, HepG2, and Huh-7 cells in a dose-dependent manner in association with tyrosine phosphorylation of c-Met and activation of phosphatidylinositol 3-kinase (PI3-K). A tyrosine kinase inhibitor (genistein) and a PI3-K inhibitor (wortmannin) prevented the migration of HCC cells. However, migration was not prevented by calphostin C, an inhibitor of protein kinase C (PKC), which is a downstream target of phospholipase Cgamma (PLCgamma). HGF also stimulated the migration of HCC cells obtained from three patients, while wortmannin prevented the migration of these cells. These results indicate that HGF stimulates the migration of HCC cells through the tyrosine phosphorylation of c-Met via activation of PI3-K.

Genetic variation of mitochondrial cytochrome b genes among the subspecies of koala, Phascolarctos cinereus.

A conserved DNA region among the subspecies of koala, of mitochondrial cytochrome b gene, was employed to analyze the genetic variation among 3 available subspecies of koala. This conserved sequence, 307 bp DNA, was sequenced using polymerase chain reaction and direct DNA sequencing technique. Substitutions in the nucleotide sequences were observed, with which koalas can be divided into 3 DNA haplotypes subspecies, but the molecular data provided inconsistency with current classification of the 3 subspecies of koala.

Clonal analysis of hematopoietic cells using a novel polymorphic site of the X chromosome.

Clonality of hematopoietic cells on a smale scale (nanogram amounts of DNA) can be detected by X-chromosome inactivation using the polymerase chain reaction (PCR). The human androgen-receptor gene (HUMARA) has a polymorphic short tandem repeat (STR), and has generally been used for clonality analysis since heterozygosity for the gene occurs in 90% of caucasian females. We examined heterozygosity of the STR on HUMARA in 110 Japanese females and found heterozygosity in 74 of 110 (67%). To examine for hematologic clonality in females with HUMARA homozygosity, we used a primer specific for a novel polymorphic STR site between DXS15 and DXS134 (DXS15-134) on Xq28. Heterozygosity for this site was found in 50 of 110 females (46%). Clonality of the hematopoietic cells was detected in 91 of 110 females (83%) using PCR of either the STR sites on HUMARA or DXS15-134. The X-inactivation patterns using PCR of DXS15-134 corresponded exactly with those obtained using PCR of HUMARA in 18 females who were heterozygous for both DXS15-134 and HUMARA. Using PCR of DXS15-134, we examined the clonality of bone marrow cells separated by flow cytometry in a patient with erythroleukemia (M6). Clonality was found not only in myeloid lineage cells but also in B lymphocytes. The clonality assay for DXS15-134 may be useful to assess for clonality of hematopoietic cells in the Japanese population, when combined with the HUMARA assay.

Suppression of growth of hepatocellular carcinoma by sodium butyrate in vitro and in vivo.

Treatment of HuH-7 human hepatocellular carcinoma (HCC) cells with 1-10 mM sodium butyrate (SB) resulted in growth inhibition in a dose-dependent manner. At 3 mM and higher concentrations, SB caused nuclear fragmentation and DNA ladder formation characteristic of apoptosis. In the treated cells, the expression of p21 (WAFI/CIPI) increased and that of alpha-fetoprotein (AFP) decreased. These characteristic changes were also observed with 5 other human HCC cell lines with or without mutation of the p53 gene. The ability of these cells to form colonies in soft agar was suppressed by either pretreating the cells with SB prior to soft agar plating or incubating untreated cells in SB-containing soft agar. Direct injection of SB into tumors developed from HuH-7 cells in nude mice resulted in an increase in the p21 level, a decrease in the tumor size and an increase in the survival time of mice. When the inoculation of HuH-7 cells into nude mice was immediately followed by subcutaneous injection of SB, development of tumors was either significantly delayed or completely suppressed. These results suggest that SB induces cellular differentiation and suppresses growth and tumorigenicity of HCC cells in vitro and in viva by a mechanism independent of p53 but possibly dependent on p21.

Cytogenetic analysis of de novo acute myeloid leukemia with trilineage myelodysplasia in comparison with myelodysplastic syndrome evolving to acute myeloid leukemia.

Characteristics of karyotypes were analyzed in de novo acute myeloid leukemia (AML) with trilineage myelodysplasia (AML/TMDS) at initial diagnosis and compared with myelodysplastic syndrome (MDS) cases that had evolved to AML (MDS/AML). Abnormal karyotypes were seen in 11 of 19 patients with AML/TMDS and 13 of 16 MDS/AML cases. Trisomy 8 was observed in 3 AML/TMDS cases as a sole anomaly and was also present in 3 MDS/AML cases but not as a sole finding. Although MDS/AML frequently displayed monosomies or long-arm deletions of chromosome 5, 7 and 9, only one case exhibited long-arm deletion (of chromosome 7) in AML/TMDS. Two or more chromosome aberrations were found in some cases in both groups. These findings suggest that AML/TMDS had passed through several preleukemic stages at diagnosis, as has been well documented in MDS and MDS/AML. Additionally, clonal evolution may have already occurred in AML/TMDS, as MDS transformed to AML is associated with clonal evolution.

Usefulness of K-ras gene mutation at codon 12 in bile for diagnosing biliary strictures.

Point mutations of the K-ras gene at codon 12 are often detected in the pancreatic juice of patients with pancreatic cancer. Detection of these mutations may, thus, have diagnostic implications. K-ras mutations may also have diagnostic potential for other biliary tumors. We sought to detect K-ras mutations in DNA obtained from bile in patients with biliary tract cancers, pancreatic cancer and benign biliary disease but who had obstructive jaundice. In 35 patients, bile was collected during percutaneous transhepatic choledocal drainage (PTCD) catheters. K-ras gene mutations at codon 12 in the samples were examined using mutant-allele-specific-amplification (MASA). We compared these results with cytological analyses of bile. K-ras mutations at codon 12 in bile were detected in 11 of 14 (79%) of the patients with biliary duct cancer, 3 of 9 (33%) with pancreatic cancer but not in patients with gallbladder cancer (n=3), papilla of Vater's cancer (n=3) or benign biliary diseases (n=6). In the patients, where cytological evaluation did not reveal malignant cells, K-ras mutations in bile were detected in 5 of 7 (71%) patients with biliary duct cancer and 2 of 5 (40%) with pancreatic cancer. This approach, when used in conjunction with bile cytology, may improve the yield in diagnosing suspected malignant tumors of the pancreatic-biliary system.

Increased expression of human DNA repair genes, XRCC1, XRCC3 and RAD51, in radioresistant human KB carcinoma cell line N10.

The radioresistant N10 and parental KB cell lines were examined for the expression of human DNA repair genes which were related to the repair of radiation-induced DNA damage by northern blot analysis using five kinds of DNA probes (XRCC1, XRCC3, XRCC5, RAD51, RAD52). In the unirradiated condition, N10 cells showed higher expression of XRCC1, XRCC3 and RAD51 mRNA than did KB cells. The X-irradiation induced a time-dependent increase in the mRNA levels of XRCC3 and RAD51 in both cell lines with a maximum at 2 h postirradiation. The XRCC1 mRNA in N10 was maintained at the same level even after irradiation, whereas that in KB was decreased after irradiation. There was no difference in the expression of XRCC5 and RAD52 mRNA between N10 and KB cells in both unirradiated and irradiated conditions. From these findings, it was suggested that XRCC1, XRCC3 and RAD51 contribute to the radioresistance in cell line N10.

The Escherichia coli ldcC gene encodes another lysine decarboxylase, probably a constitutive enzyme.

A gene (designated ldcC) mapped at 4.6 min on the Escherichia coli chromosome codes for a protein of 713 amino acids (aa) that shows strong similarities in both size and amino-acid sequence (69% identical residues and 85% conserved residues) to lysine decarboxylase (LDC) from E. coli (CadA, acid-inducible LDC, 715 aa) or from Hafnia alvei (739 aa). A pUC18 derivative carrying the ldcC gene conferred high LDC activities on an E. coli strain devoid of the functional cadA gene, even when the bacteria were grown under non-inducing conditions at physiological pH. Thus, the gene encodes another lysine decarboxylase, probably a constitutively expressed enzyme, the presence of which was suggested from the previous observations that low LDC activities were detectable in cadA- mutant and non-induced wild-type cells.

Direct assessment of triploid cells in mosaic human fetuses by fluorescence in-situ hybridization.

Villous tissues from 30 spontaneous abortions and the same number of artificial abortions were obtained and analysed for the frequency of polyploid cells. Single cell suspensions were made from these tissues without culture and the ploidy of > 100 cells was analysed. Trisomies of chromosomes 17 and 4 have rarely been reported in villous cells of spontaneous abortions, suggesting that the presence of more than three copies of chromosomes 17 and 4 per cell indicates polyploidy. The number of chromosomes 17 and 4 was detected by fluorescence in-situ hybridization analysis using centromeric probes D17Z1 and D4Z1. Most villous cells from cases of spontaneous and artificial abortions had two D17Z1 or D4Z1 signals per cell, with very small percentages of cells (0.5 +/- 0.4%) showing three signals per cell. However, in four cases of spontaneous abortions, 2-12% of cells had three D17Z1 or D4Z1 signals per cell. This indicates the presence of triploid cells in these cases of spontaneous abortion, at a significantly higher frequency compared to artificial or the remaining 26 cases of spontaneous abortion. In addition, three cases contained 0.2-0.4% of cells showing six signals, indicating that these cells were dividing triploid cells. The low frequency of mosaicism reported here would not be detectable by conventional chromosomal analysis.