Mutational analysis of BRCA1 and BRCA2 and clinicopathologic analysis of ovarian cancer in 82 ovarian cancer families: two common founder mutations of BRCA1 in Japanese population

We analyzed genetic alterations in BRCA1 and BRCA2 genes among 82 ovarian cancer families in Japan. The clinical characteristics of BRCA-associated ovarian cancer patients were compared with cases carrying no mutations as well as with population controls. Using a direct sequencing method, 45 of the 82 ovarian cancer families were found to carry BRCA1 or BRCA2 germ-line mutations (40 with BRCA1 and 5 with BRCA2). In 24 independent mutations of BRCA1, 5 recurrent mutations were found and 2 of them, the L63X and Q934X mutations, were detected in seven and eight independent families, respectively. In addition, 16 mutations of BRCA1 and 3 mutations of BRCA2 have never been described previously. In consideration of clinicopathological features, there was a significantly higher proportion of tumors with serous adenocarcinoma and of cases of advanced stages in the BRCA1 or BRCA2 cases than in those of the controls. On the other hand, there were no differences of mean age at diagnosis between patients with BRCA1 or BRCA2 mutation and those of the controls. Our results indicate that the features of BRCA-associated ovarian cancer in Japan appear to be similar to those in Western countries, and the L63X and Q934X mutations of BRCA1 appear to be common founder mutations unique to the Japanese population.

Behavior of restriction-modification systems as selfish mobile elements and their impact on genome evolution

Restriction-modification (RM) systems are composed of genes that encode a restriction enzyme and a modification methylase. RM systems sometimes behave as discrete units of life, like viruses and transposons. RM complexes attack invading DNA that has not been properly modified and thus may serve as a tool of defense for bacterial cells. However, any threat to their maintenance, such as a challenge by a competing genetic element (an incompatible plasmid or an allelic homologous stretch of DNA, for example) can lead to cell death through restriction breakage in the genome. This post-segregational or post-disturbance cell killing may provide the RM complexes (and any DNA linked with them) with a competitive advantage. There is evidence that they have undergone extensive horizontal transfer between genomes, as inferred from their sequence homology, codon usage bias and GC content difference. They are often linked with mobile genetic elements such as plasmids, viruses, transposons and integrons. The comparison of closely related bacterial genomes also suggests that, at times, RM genes themselves behave as mobile elements and cause genome rearrangements. Indeed some bacterial genomes that survived post-disturbance attack by an RM gene complex in the laboratory have experienced genome rearrangements. The avoidance of some restriction sites by bacterial genomes may result from selection by past restriction attacks. Both bacteriophages and bacteria also appear to use homologous recombination to cope with the selfish behavior of RM systems. RM systems compete with each other in several ways. One is competition for recognition sequences in post-segregational killing. Another is super-infection exclusion, that is, the killing of the cell carrying an RM system when it is infected with another RM system of the same regulatory specificity but of a different sequence specificity. The capacity of RM systems to act as selfish, mobile genetic elements may underlie the structure and function of RM enzymes.

Inflammatory cytokines in vitreous fluid and serum of patients with diabetic vitreoretinopathy

To determine whether inflammatory cytokines are increased in proliferative diabetic retinopathy. We measured concentrations of interleukin-6, 8 (IL-6, 8) and tumor necrosis factor (TNF)-alpha by enzyme-linked immunosorbent assay (ELISA) in vitreous and serum from 47 patients with proliferative diabetic retinopathy and 21 patients with vitreous noninflammatory retinopathies. Vitreous concentration of IL-6 were 64.7+/-12.8 pg/ml in proliferative diabetic retinopathy, much greater (P<.005) than in noninflammatory retinopathy (2.8+/-4.5 pg/ml). Amounts of IL-8 in vitreous fluid also were greater in proliferative retinopathy than in noninflammatory retinopathy (34.0+/-11.5 vs. 6.1+/-2.0 pg/ml, P<.005). Concentrations of TNF-alpha in vitreous fluid were not statistically different in proliferative retinopathy from those in noninflammatory retinopathy. In sera, concentrations of IL-6 and IL-8 were not different between proliferative and noninflammatory retinopathy. However, serum TNF-alpha was much greater in proliferative retinopathy than in noninflammatory retinopathy (0.81+/-0.72 vs. 0.09+/-0.00 pg/ml, P<.001). Elevated TNF-alpha in serum then may be diagnostically useful in proliferative diabetic retinopathy. And inflammatory cytokines in vitreous may be pathogenically important in this concentration.

Detection of point mutation for human growth hormone in patients with anti-pituitary antibody positive type 1 diabetes mellitus

We investigated genetic mutations in the coding region of the human growth hormone (hGH) gene in anti-pituitary antibody (APA)-positive patients with type 1 diabetes mellitus (n = 6) or autoimmune thyroid diseases (n = 10) and in APA-negative, healthy controls (n = 10). A point mutation in the hGH gene was discovered in two patients with type 1 diabetes mellitus. No mutations were found in the hGH gene in control subjects, patients with autoimmune thyroid diseases (Hashimoto's thyroiditits, Graves' disease) or in the remaining four patients with type 1 diabetes mellitus. The mutation was located in the coding region for the second amino acid in the N-terminal region of hGH. This point mutation was identified in codon 2 in exon 2 of the hGH gene. We successfully developed an allele-specific amplification method for detecting this mutation using the polymerase chain reaction.

Comparison of Neisseria gonorrhoeae isolates from the genital tract and pharynx of two gonorrhea patients

Neisseria gonorrhoeae was isolated simultaneously from urethral and pharyngeal specimens of two gonorrhea patients. The pair of isolates from one of the two patients were identical in auxotype, pulsed-field gel electrophoresis pattern, and antimicrobial susceptibility, which indicated that both sites in that patient were infected with the same strain of N. gonorrhoeae. However, the two isolates from the other patient had different properties, indicating that the two sites in the second patient were infected with different strains. The gonococcal infections in these patients failed to respond to initial treatment with sparfloxacin or sulbactam/ampicillin, because the causative strains of N. gonorrhoeae were resistant to the respective antibiotics. Variable patterns and routes of gonococcal infection have recently been discovered in individual patients, suggesting that specimens for bacterial isolation should be taken not just from one site but from various sites that might be infected. This method may contribute to the successful treatment and epidemiological investigation of gonococcal infections.

Sphingosine 1-phosphate may be a major component of plasma lipoproteins responsible for the cytoprotective actions in human umbilical vein endothelial cells

Sphingosine 1-phosphate (S1P), a novel lipid mediator, is concentrated in the fraction of lipoproteins that include high density lipoprotein (HDL) and low density lipoprotein (LDL) in human plasma. Here, we show that oxidation of LDL resulted in a marked reduction in the S1P level in association with a marked accumulation of lysophosphatidylcholine (LPC). We therefore investigated the role of the lipoprotein-associated lipids especially S1P in the lipoprotein-induced cytoprotective or cytotoxic actions in human umbilical vein endothelial cells. The viability of the cells gradually decreased in the absence of serum or growth factors in the culture medium. The addition of oxidized LDL (ox-LDL) accelerated the decrease in the cell viability. LPC and 7-ketocholesterol mimicked ox-LDL actions. On the other hand, HDL and LDL almost completely reversed the serum deprivation- or ox-LDL-induced cytotoxicity. Exogenous S1P mimicked cytoprotective actions. Moreover, the S1P-rich fraction and chromatographically purified S1P from HDL exerted cytoprotective actions, but the rest of the fractions did not. The cytoprotective actions of HDL and S1P were associated with extracellular signal-regulated kinase (ERK) activation and were almost completely inhibited by pertussis toxin and PD98059, an ERK kinase inhibitor. The HDL-induced action was specifically desensitized in the S1P-pretreated cells. Taken together, these results indicate that the lipoprotein-associated S1P and the lipid receptor-mediated signal pathways may be responsible for the lipoprotein-induced cytoprotective actions. Furthermore, the decrease in the S1P content, in addition to the accumulation of cytotoxic substances such as LPC, may be important for the acquisition of the cytotoxic property to ox-LDL.

Positive correlation between circulating leptin levels and lipid lipoproteins in postmenopausal women administered hormone replacement therapy

Beneficial effects of hormone replacement therapy are reported on plasma concentrations of lipids and lipoproteins. Plasma leptin levels are reported to reflect lipid metabolism. We treated 40 healthy postmenopausal women with continuous combined HRT (0.625 mg conjugated equine estrogen and 2.5 mg medroxyprogesterone acetate orally) daily for 6 months and then investigated total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol, which are considered to be factors inducing cardiovascular disease (CVD). We measured the plasma levels of lipids and leptin, which are considered to be altered with HRT. Plasma leptin and lipid levels were measured at baseline and after 3 and 6 months of HRT. The plasma levels of leptin in PMW were not significantly reduced by HRT. Although the plasma levels of total cholesterol and LDL-cholesterol did not change by HRT, the administration of HRT significantly increased plasma levels of triglycerides and HDL-cholesterol in PMW. The correlation between leptin and total cholesterol or triglycerides was positive after HRT while these relations were not correlated at baseline. The correlation between lipid levels and leptin may explain the new role of leptin in plasma lipid levels in HRT.

Expression of Set-alpha during morphogenesis of mouse lower first molar

The detailed in situ expression pattern of the Set-alpha gene has been studied. Previously we showed that Set-alpha is a differentially expressed gene in the embryonic mouse mandible at day 10.5 (E10.5) gestational age. Cells expressing Set-alpha were widely distributed in both the epithelial and underlying ectomesenchymal cells at E10.5. At E12, they were slightly aggregated in an area where tooth germ of the lower first molar is estimated to be formed. At E13.5, Set-alpha was strongly expressed in the tooth germ. At the cap stage, Set-alpha was expressed in the enamel organ and dental papilla. At the bell stage, Set-alpha was distinctly expressed in the inner enamel epithelial and dental papilla cells facing the inner enamel epithelial layer, which were intended to differentiate into ameloblasts and odontoblasts, respectively. Interestingly, Set-alpha was also expressed in several embryonic craniofacial tissues derived from the ectoderm. This study is the first report that Set-alpha is distinctly expressed in the developing tooth germ, and suggests that Set-alpha plays an important role in both the initiation and the growth of the tooth germ, as well as in the differentiation of ameloblasts and odontoblasts.

Up-regulated TGF-beta mRNA expression in splenic T cells of high IgA-prone mice: a murine model of IgA nephropathy with glomerulosclerosis

BACKGROUND/AIMS

Recently, we established a high serum IgA-prone inbred (HIGA) mouse strain as a murine model of spontaneous IgA nephropathy by selective mating of high serum IgA ddY mice, and found that they showed enhanced production of glomerular extracellular matrix components with increased expression of TGF-beta mRNA and protein in the kidneys. In this study, we examined the roles of lymphocytes in the development of high serum IgA in this strain.

METHODS

We performed flow cytometric analyses of T and B cells in splenic mononuclear cells (SMNCs) from these mice using BALB/c mice as normal controls. We also compared serum TGF-beta1 concentrations and TGF-beta mRNA expression levels in the B-cell-depleted (T-cell-rich) fraction of SMNCs in these mice.

RESULTS

HIGA mice showed significantly fewer CD3-positive cells compared with BALB/c mice when young, but not when aged. The CD4/CD8 ratio of HIGA mice was lower than that of BALB/c mice, but this difference was not significant. Although the number of B220-positive cells did not vary significantly, the ratio of surface IgA-positive B cells was significantly increased in both young and adult HIGA mice. The B-cell-depleted SMNCs from HIGA mice exhibited higher levels of expression of TGF-beta and TGF-beta1 mRNA than controls from a young age, which were maintained throughout life, but there were no differences in PDGF, MCP-1 or bFGF expression between these two strains. In contrast to local mRNA expression, serum TGF-beta1 concentration was decreased in HIGA mice compared with BALB/c controls.

CONCLUSION

These findings suggest that the mating procedure performed to establish HIGA mice selected for a unique phenotype of local up-regulation of TGF-beta production in the kidneys, as well as T cells that may contribute to both the early and consistently high serum IgA expression and enhanced production of renal extracellular matrix components in HIGA mice. Additionally, TGF-beta1 may act locally, not systemically, in a paracrine or autocrine manner.

Antimicrobial susceptibilities of Helicobacter pylori isolates under microaerophilic atmospheres established by two different methods

The MICs of clarithromycin, amoxicillin, and metronidazole for 150 Helicobacter pylori isolates were determined using the AnaeroPack system and were compared with those determined using a microaerophilic incubator. The MICs of clarithromycin, amoxicillin, and metronidazole determined under both microaerophilic atmospheres were mostly within one twofold dilution for 146 (97.3%), 150 (100%), and 149 (99.3%) of the isolates, respectively.

Di(2-ethylhexyl)phthalate induces hepatocellular adenoma in transgenic mice carrying a human prototype c-Ha-ras gene in a 26-week carcinogenicity study

To evaluate the transgenic mouse carrying a human prototype c-Ha-ras gene (rasH2 mouse) as a model for 26-week carcinogenicity tests, Di(2-ethylhexyl)phthalate (DEHP), a peroxisome proliferator, was administered to 15 rasH2 mice/sex/group at concentrations of 1,500, 3,000 or 6,000 ppm, and to 15 wild-type (non-Tg) mice/sex/group at a concentration of 6,000 ppm in their diets for 26 weeks. Survival rates and food consumption in the groups treated with DEHP and in the control group were similar. Body weight gain in rasH2 and non-Tg mice at 6,000 ppm in the terminal week decreased about 10% as compared to the control group. Common findings related to treatment with DEHP in rasH2 and non-Tg mice included hypertrophy with coarse granules and deposit of pigment in the liver, hydronephrosis and tubular regeneration in the kidney, focal atrophy in the testis, and increased eosinophilic body in the nasal cavity. Hepatocellular adenoma was induced by treatment with DEHP, and was confined to male rasH2; mice the incidence being 7%(1/15), 13%(2/15), and 27%(4/15) in the 1,500-, 3,000-, and 6,000-ppm group, respectively. Point mutation was not detected in codon 12 and 61 of human c-Ha-ras transgene upon DNA analyses on frozen samples taken from these hepatocellular adenomas. From the results obtained in this 26-week carcinogenicity study, it is concluded that DEHP is a hepato-carcinogen for transgenic mouse carrying a human prototype c-Ha-ras gene.

Correlation of circulating interleukin-10 with thyroid hormone in acute myocardial infarction

In patients with acute myocardial infarction (AMI), euthyroid sick syndrome (ESS) has been reported to be linked to increase in interleukin (IL)-6 and activation of its receptors. Recent reports have shown that IL-10, an anti-inflammatory cytokine, also plays a key role in the pathogenesis of AMI. Therefore we investigated the relationship between thyroid state and IL-10 in patients with AMI. We measured thyrotropin (TSH), free triiodothyronine (FT3), free thyroxine (FT4), IL-10, and IL-6 in plasma from 20 patients with AMI and 20 healthy controls. All 20 AMI patients showed significantly lower concentrations of FT3 than in controls accompanied by normal or subnormal levels of TSH, characterized ESS. Concentrations of IL- 10 and IL-6 were higher in patients than in controls. Both IL-10 and IL-6 significantly (p<0.05, respectively) correlated with thyroid hormone in patients with AMI. Time course of IL-10, IL-6, and FT3 seemed to be tightly linking. In conclusion, IL-10 and IL-6 appears to affect thyroid hormone homeostasis in patients with AMI.

Type IV collagen serum and vitreous fluid levels in patients with diabetic retinopathy

We compared the levels of type IV collagen (IV-C) in vitreous fluid and serum and the levels of glycosylated haemoglobin in 47 patients with proliferative diabetic retinopathy (DR) and 21 patients with non-inflammatory retinopathies. Levels of IV-C were found to be higher in the vitreous fluid in patients with DR than in patients with non-inflammatory retinopathy (53.2 +/- 14.9 microg/l versus 14.7 +/- 4.5 microg/l). Serum levels were likewise higher in patients with DR (349.7 +/- 106.2 microg/l versus 97.7 +/- 13.1 microg/l) as were glycosylated haemoglobin levels (8.3 +/- 0.3% versus 5.2 +/- 0.4%). In addition, levels of type IV collagen in the vitreous fluid were found to be higher in the patients who had been diabetic for > or = 10 years than in patients who had been diabetic for < 10 years (54.8 +/- 15.5 microg/l versus 16.8 +/- 4.6 microg/l). We conclude that accumulation of vitreous fluid IV-C may relate to high levels of glycosylated haemoglobin and long duration of diabetes. This suggests that the concentration of IV-C in vitreous fluid, and possibly also the serum levels of IV-C, reflects the progression of DR. Further investigation is needed to verify this and to investigate whether or not measuring IV-C levels is a useful means to assess therapeutic effects and/or prognosis of diabetic microangiopathy.

Localization of a novel susceptibility gene for familial ovarian cancer to chromosome 3p22-p25

We performed genome-wide linkage analysis in 58 patients and nine unaffected members among 28 families with no mutation in BRCA1 or BRCA2, employing a set of 410 microsatellite markers. We initially screened the whole genome, including the X chromosome, by a non-parametric method using the GENEHUNTER program. As a result, chromosome 3p22-p25 showed a suggestive score for linkage [LOD = 3.49 and non-parametric LOD (NPL) = 2.77 at D3S3611] based on a multipoint analysis. Additionally, based on a two-point analysis using dense markers, this 3p22-p25 region showed a P-value < 0.05 at 10 markers and there is suggestive evidence for linkage at two markers within approximately 19 cM (NPL = 2.60 and 2.49 at D3S1597 and D3S3611, respectively). To explore whether the candidate gene in this 3p22-p25 region contributed to carcinogenesis of familial ovarian cancer in a similar fashion to the tumor suppressor gene, we performed loss of heterozygosity (LOH) analysis. It was observed that the frequency of LOH at four markers in this region was >50% only in tumor tissues from patients with no mutation in BRCA1 or BRCA2, not in those with a BRCA1 mutation.

Caspase-independent apoptosis induced by differentiation-inducing factor of Dicytostelium discoideum in INS-1 cells

Differentiation-inducing factor (DIF) is a lipophilic hormone of Dicytostelium discoideum and has been shown to exert diverse effects in mammalian cells. We investigated the effect of DIF on cell viability in insulin-secreting INS-1 cells. DIF induced cell death in a dose-dependent manner. In DIF-treated cells, nuclear condensation and shrinkage of the cell body were observed. After 6 h of DIF treatment, cells became Tdt-mediated dUTP-biotin nick end-labeling-positive, and DNA ladder formation was detected, indicating that DIF induced apoptosis in these cells. DIF did not activate caspase-3, a key enzyme mediating apoptotic signals generated by various agents. Furthermore, DIF-induced cell death was not affected by Z-asp-2, 6-dichlorobenzoyloxymethylketone, a broad inhibitor of the caspases. As is the case in other types of cells, DIF increased cytoplasmic free calcium concentration in INS-1 cells. However, DIF-induced cell death was not affected by chelating intracellular free calcium by 1, 2-bis(2-aminoophenoxy)ethane-N, N, N, N-tetra acetic acid (BAPTA). These results indicate that DIF induces apoptosis in INS-1 cells by a mechanism independent of caspase-3. DIF-induced elevation of cytoplasmic calcium does not mediate the effect of DIF on cell death.

Non-invasive diagnosis of a Schwannoma by ultrasonography: a case study

A 52-year-old female came to this institution complaining of a right leg mass lesion. Ultrasonography showed a 16 x 12 x 20mm hypoechoic solid mass lesion in the right leg. The patient underwent surgery during the diagnosis of Schwannoma. Preoperative diagnosis of Schwannoma is difficult by examination. Computerized tomography and magnetic resonance imaging, showed the origin of Schwannoma. However, the lesion was noted to be in a direct continuity with the cord-like echogenic structure consistent with a nerve by echography. We prefer to conduct preoperative examination by ultrasonography in patients with Schwannoma. In conclusion, we have reported a case of Schwannoma diagnosed by non-invasive ultrasonography.

Detection of differentially expressed genes in the early developmental stage of the mouse mandible

We previously examined the development of the mouse mandible, and demonstrated that odontogenesis occurs between embryonic day 10.5 (E10.5) and E12. Based on the histological findings, we performed cDNA subtraction between the E10.5 and E12 mandibles to detect any differentially expressed genes which might be involved in the initiation of odontogenesis. By sequencing, homology search and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), we thus found Pgk-1, Ccte, Hsp86, Nucleolin, Hsc73, Frg1, N-ras, Set alpha and Hsj2 from the E10.5 mandible, and E25, ATPase6, Mum2, Thymosin beta4 and L21 from the E12 mandible to be differentially expressed genes. These genes are functionally related to protein transport, signal transduction, transcription, translation and molecular chaperon activity. In situ hybridization analyses of Set alpha and E25 showed that Set alpha was detected in the tooth germ at E12 and E14.5, thus indicating a close relationship of this gene to odontogenesis. Meanwhile, the in situ signal of E25 was found in the muscular layer of the tongue, thus suggesting E25 to be related to the differentiation of muscular tissue. In conclusion, we found 15 differentially expressed genes in the course of the early developmental stage of the mouse mandible using a combination of the cDNA subtraction and semi-quantitative RT-PCR methods, while in addition, two genes were demonstrated to be related to the initiation and the development of both tooth germ and the tongue according to the in situ hybridization technique.

Mammary duct ectasia in children presenting bloody nipple discharge: a case in a pubertal girl

Mammary duct ectasia occurs rarely in childhood. The authors report on the case of a pubertal girl who was operated on for duct ectasia with bloody nipple discharge. Duct ectasia is regarded as a primary lesion; it is considered to be a cause of bloody secretion, and it has a mechanism similar to that of mammary duct papilloma.

Localization of activated caspase-3-positive and apoptotic cells in the developing tooth germ of the mouse lower first molar

This study examined the immunohistochemical detection of activated caspase-3, and its association with apoptosis, during tooth morphogenesis of the mouse lower first molar. The distribution of cells positive for caspase-3 closely corresponded with the localization of the terminal deoxynucleotidyl transferase-mediated deoxyuridine-5'-triphosphate-biotin nick end labelling (TUNEL)-positive apoptotic cells through the developmental course of tooth germs from embryo day 12 (E12) to E19, thus showing that the apoptosis occurring in the developing odontogenic tissue was induced by the activation of the caspase family. The specific distribution pattern of apoptotic cells in the developing odontogenic epithelial tissue from the initiation (E12) of tooth germ to the completion of tooth crown morphology (E19) also suggests that apoptotic events are related not only to a deletion of functionally suspended cells, but also participate in initiation and the completion of tooth morphogenesis. Electron microscopic examination revealed that apoptotic cells were present in the primary enamel knot, and these apoptotic cells were phagocytized by neighbouring odontogenic epithelial cells, thus indicating the prompt disposal of any dead cells by epithelial cells.

Evaluation of signal-averaged electrocardiography for clinical diagnosis in arrhythmogenic right ventricular dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a heart muscle disorder of unknown etiology that is characterized pathologically by fibrofatty replacement of the right ventricular myocardium. We investigated the relationship between the electrocardiogram (ECG) appearances and signal-averaged ECG (SAECG) in 7 cases with ARVD, and evaluated the usefulness of SAECG as a screening test to detect patients with ARVD. Compared with the conventional 12-lead ECG, the SAECG detects abnormalities at a higher rate in ARVD patients (57% versus 86%). SAECG was more sensitive as a screening test to detect patients with ARVD than 12-lead ECG.

Experimental genome evolution: large-scale genome rearrangements associated with resistance to replacement of a chromosomal restriction-modification gene complex

Type II restriction enzymes are paired with modification enzymes that protect type II restriction sites from cleavage by methylating them. A plasmid carrying a type II restriction-modification gene complex is not easily replaced by an incompatible plasmid because loss of the former leads to cell death through chromosome cleavage. In the present work, we looked to see whether a chromosomally located restriction-modification gene complex could be replaced by a homologous stretch of DNA. We tried to replace the PaeR7I gene complex on the Escherichia coli chromosome by transducing a homologous stretch of PaeR7I-modified DNA. The replacement efficiency of the restriction-modification complex was lower than expected. Some of the resulting recombinant clones retained the recipient restriction-modification gene complex as well as the homologous DNA (donor allele), and slowly lost the donor allele in the absence of selection. Analysis of their genome-wide rearrangements by Southern hybridization, inverse polymerase chain reaction (iPCR) and sequence determination demonstrated the occurrence of unequal homologous recombination between copies of the transposon IS3. It was strongly suggested that multiple rounds of unequal IS3-IS3 recombination caused large-scale duplication and inversion of the chromosome, and that only one of the duplicated copies of the recipient PaeR7I was replaced.

Whole genome sequencing of meticillin-resistant Staphylococcus aureus

BACKGROUND

Staphylococcus aureus is one of the major causes of community-acquired and hospital-acquired infections. It produces numerous toxins including superantigens that cause unique disease entities such as toxic-shock syndrome and staphylococcal scarlet fever, and has acquired resistance to practically all antibiotics. Whole genome analysis is a necessary step towards future development of countermeasures against this organism.

METHODS

Whole genome sequences of two related S aureus strains (N315 and Mu50) were determined by shot-gun random sequencing. N315 is a meticillin-resistant S aureus (MRSA) strain isolated in 1982, and Mu50 is an MRSA strain with vancomycin resistance isolated in 1997. The open reading frames were identified by use of GAMBLER and GLIMMER programs, and annotation of each was done with a BLAST homology search, motif analysis, and protein localisation prediction.

FINDINGS

The Staphylococcus genome was composed of a complex mixture of genes, many of which seem to have been acquired by lateral gene transfer. Most of the antibiotic resistance genes were carried either by plasmids or by mobile genetic elements including a unique resistance island. Three classes of new pathogenicity islands were identified in the genome: a toxic-shock-syndrome toxin island family, exotoxin islands, and enterotoxin islands. In the latter two pathogenicity islands, clusters of exotoxin and enterotoxin genes were found closely linked with other gene clusters encoding putative pathogenic factors. The analysis also identified 70 candidates for new virulence factors.

INTERPRETATION

The remarkable ability of S aureus to acquire useful genes from various organisms was revealed through the observation of genome complexity and evidence of lateral gene transfer. Repeated duplication of genes encoding superantigens explains why S aureus is capable of infecting humans of diverse genetic backgrounds, eliciting severe immune reactions. Investigation of many newly identified gene products, including the 70 putative virulence factors, will greatly improve our understanding of the biology of staphylococci and the processes of infectious diseases caused by S aureus.

Combined immunodeficiency, chromosomal instability, and postnatal growth deficiency in a Japanese girl

We report on an 11-year-old Japanese girl with combined immunodeficiency and chromosomal instability. She had postnatal growth deficiency and microcephaly, preaxial polydactyly of the left hand, and susceptibility to infections. Immunological studies showed marked lymphocytopenia (around 500/ll), reduced lymphocyte response to various mitogens, and reduced or absent serum IgA, IgG, and IgM. Cell biological studies of her primary skin fibroblasts demonstrated spontaneous chromosome aberrations and radiation hypersensitivity. The combination of immunodeficiency, chromosomal instability, and radiation hypersensitivity as seen in the girl is present in both ataxia-telangiectasia and Nijmegen breakage syndrome. Ataxia-telangiectasia was excluded because of differences in clinical features and laboratory data. Likewise, Nijmegen breakage syndrome is unlikely to be the case because the characteristic face, hyperpigmented spots, and mental retardation present in the syndrome were missing in the girl. Sequence analysis of a Nijmegen breakage syndrome responsible gene, NBS1, revealed no mutations. A normal NBS1 product was also demonstrated by immunoblot analysis using an anti-NBS1 antibody. We propose that the disorder in the girl represents a new combination of combined immunodeficiency and chromosomal instability.