Tumor Promotion by 12-O-Tetradecanoylphorbol-13-Acetate in an Ultra-Short-Term Skin Carcinogenesis Bioassay Using rasH2 Mice

Assessment of the skin tumor–promoting potential of 12- O-tetradecanoylphorbol-13-acetate (TPA) after initiation with 7,12-dimethylbenz[ a]anthracene (DMBA) was conducted using rasH2 transgenic (Tg) mice and their nontransgenic (non-Tg) littermates. Mice were treated with DMBA (50 μg/100 μL acetone) on clipped back skin at the commencement of the study, and 1 week thereafter, TPA was applied at 8 μg/200 μL or 4 μg/200 μL acetone, once or twice weekly, for 7 weeks. Skin nodules were observed in the rasH2 Tg mice from week 4, and the incidence reached 100% at weeks 5 and 6. The number of skin nodules (multiplicity) in the 8-μg twice-weekly, 8-μg once-weekly, 4-μg twice-weekly, and 4-μg once-weekly groups was 62.4, 46.2, 62.6, and 36.9, respectively. The non-Tg mice also developed skin nodules, but the sensitivity to induction in the rasH2 Tg mice was higher. No nodules were observed in the acetone groups, but single nodules were apparent in the no-treatment rasH2 Tg and non-Tg groups. In conclusion, skin promotion effects could be detected within only 8 weeks in the rasH2 mice, and the concentration of 4 μg TPA once weekly was sufficient as a positive control. This short-term skin carcinogenesis bioassay using rasH2 mice could represent a useful tool for the assessment of drug and chemical safety with cutaneous treatment.

Studies of severe acute respiratory syndrome coronavirus pathology in human cases and animal models

During the severe acute respiratory syndrome (SARS) outbreak of 2003, approximately 10% of SARS patients developed progressive respiratory failure and died. Since then, several animal models have been established to study SARS coronavirus, with the aim of developing new antiviral agents and vaccines. This short review describes the pathologic features of SARS in relation to their clinical presentation in human cases. It also looks at animal susceptibility after experimental infection, animal models of SARS, and the pathogenesis of this disease. It seems that adaptation of the virus within the host animal and the subsequent abnormal immune responses may be key factors in the pathogenesis of this new and fatal respiratory disease. The proteases produced in the lung during inflammation could also play an important role for exacerbation of SARS in animals.

Validation of proteomic classifier for clinical benefit from erlotinib as first line treatment for advanced non-small cell lung cancer (ECOG 3503)

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Background: In this study we tested the ability of our serum mass spectrometry classifier of clinical benefit from gefitinib to classify pre-treatment sera and plasma samples from non-small cell lung cancer (NSCLC) patients treated first line with erlotinib in ECOG E3503. Methods: Pretreatment serum and plasma samples were available from 73 of the 96 previously untreated advanced NSCLC patients treated with single agent erlotinib on ECOG protocol 3503, 13 subjects had only serum samples, and 10 had only plasma samples. All of these samples analyzed in replicate by MALDI mass spectrometry (MS). A prediction algorithm we established based on a training cohort of 139 patients treated second or third line with gefitinib was used to classify these patients for survival and time to progression, and results obtained from serum and plasma were compared when both were available Results: We found that the signals for the 8 distinct mass-to-charge (m/z) features used in our classifier were highly concordant between serum and plasma samples from the same patient, and that there was no difference in the classification of the patients between serum and plasma when both were available. Therefore we classified all 96 patients using serum if available, and plasma if not. The classification algorithm very successfully classified patients into groups with good and poor survival (median survival of 306 days vs 107 days, p = 0.0007). With the available follow-up, the time to progression was also statistically significant in this group (p = 0.007, data not shown). In a Cox multivariate analysis including the most significant univariate parameters PS (0 vs. 1 vs 2), number of involved sites (=3 vs >3) and prior weight loss (<5% vs = 5%), the MALDI MS classification algorithm retained independent significance at p = 0.03, with a hazard ratio of 0.53. Conclusions: This multi-institutional ECOG study demonstrates that MALDI MS can assist in the pre-treatment selection of a subgroup of NSCLC patients who are likely to show improved survival after treatment with first line erlotinib.

No significant financial relationships to disclose.

Prediction of clinical outcome in non-small cell lung cancer (NSCLC) patients treated with gefitinib using Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) of serum

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Background: Assessment of epidermal growth factor receptor (EGFR) gene copy number, mutational status, and protein levels may predict response and possibly survival following treatment with EGFR tyrosine kinase inhibitors, but all these methods require tumor tissue, highlighting the need for a non-invasive predictive test. We evaluated the ability of MALDI-TOF MS profiling of serum to predict which patients (Pts) with NSCLC were likely to benefit from gefitinib treatment. Methods: Serum from Pts with NSCLC, collected prior to treatment with gefitinib, was subjected to MALDI-TOF MS using Voyager DE-STR or DE-PRO instruments. Replicate mass spectra obtained at two institutions were submitted to a third party for processing (background subtraction, noise estimation, normalization, spectral alignment and peak identification) and selection of discriminating mass/charge (m/z) values from a training cohort of 70 Caucasian Pts. The predictive capability of the profile was then assessed in independent cohorts of NSCLC Pts. Results: Intra- and inter- laboratory reproducibility of MALDI spectra were excellent. A set of 11 m/z values (mass range 5 - 12.5 kDa) predictive of clinical benefit were identified in the training cohort and confirmed by leave-one-out cross validation. Spectra from 19/70 Pts in the training cohort were unclassifiable. For the remaining 51 Pts the algorithm discriminated groups more or less likely to benefit with respect to time to progression (median 3.0 vs. 1.5 mo., p = 0.0325) and overall survival (median 14.6 vs. 2.3 mo., p = 0.0128). Validation was performed in an independent cohort consisting of serum from 69 Japanese Pts. Spectra from 13/69 Pts were unclassifiable. For the remaining 56 Pts it was possible to identify a group with superior time to progression (median 14.8 vs. 2.1 mo., p = 0.0012) and overall survival (median 19.1 vs. 7.9 mo., p = 0.0102). Conclusions: MALDI-TOF MS of pretreatment serum may aid with the identification of subsets of NSCLC Pts that will benefit from treatment with gefitinib. This algorithm is currently being evaluated in an expanded cohort of Pts receiving gefitinib treatment and in Pts treated with erlotinib.

[Table: see text]

An effective iodide formulation for killing Bacillus and Geobacillus spores over a wide temperature range

AIMS

To develop a sporicidal reagent which shows potent activity against bacterial spores not only at ambient temperatures but also at low temperatures.

METHODS AND RESULTS

Suspension tests on spores of Bacillus and Geobacillus were conducted with the reagent based on a previously reported agent (N. Kida, Y. Mochizuki and F. Taguchi, Microbiology and Immunology 2003; 47: 279-283). The modified reagent (tentatively designated as the KMT reagent) was composed of 50 mmol l(-1) EDTA-2Na, 50 mmol l(-1) ferric chloride hexahydrate (FeCl(3).6H(2)O), 50 mmol l(-1) potassium iodide (KI) and 50% ethanol in 0.85% NaCl solution at pH 0.3. The KMT reagent showed significant sporicidal activity against three species of Bacillus and Geobacillus spores over a wide range of temperature. The KMT reagent had many practical advantages, i.e. activity was much less affected by organic substances than was sodium hypochlorite, it did not generate any harmful gas and it was stable for a long period at ambient temperatures. The mechanism(s) of sporicidal activity of the KMT reagent was considered to be based on active iodine species penetrating the spores with enhanced permeability of the spore cortex by a synergistic effect of acid, ethanol and generated active oxygen.

CONCLUSIONS

The data suggest that the KMT reagent shows potent sporicidal activity over a wide range temperatures and possesses many advantages for practical applications.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results indicate development of a highly applicable sporicidal reagent against Bacillus and Geobacillus spores.

The DeltafliD mutant of Pseudomonas syringae pv. tabaci, which secretes flagellin monomers, induces a strong hypersensitive reaction (HR) in non-host tomato cells

To investigate the role of flagella and monomer flagellin in the interaction between Pseudomonas syringae pv. tabaci and plants, non-polar fliC and fliD mutants were produced. The ORFs for fliC and fliD are deleted in the DeltafliC and DeltafliD mutants, respectively. Both mutants lost all flagella and were non-motile. The DeltafliC mutant did not produce flagellin, whereas the DeltafliD mutant, which lacks the HAP2 protein, secreted large amounts of monomer flagellin into the culture medium. Inoculation of non-host tomato leaves with wild-type P. syringae pv. tabaci or the DeltafliD mutant induced a hypersensitive reaction (HR), whereas the DeltafliC mutant propagated and caused characteristic symptom-like changes. In tomato cells in suspension culture, wild-type P. syringae pv. tabaci induced slight, visible HR-like changes. The DeltafliC mutant did not induce HR, but the DeltafliD mutant induced a remarkably strong HR. Expression of the hsr203J gene was rapidly and strongly induced by inoculation with the DeltafliD mutant, compared to inoculation with wild-type P. syringae pv. tabaci. Furthermore, introduction of the fliC gene into the DeltafliC mutant restored motility and HR-inducing ability in tomato. These results, together with our previous study, suggest that the flagellin monomer of pv. tabaci acts as a strong elicitor to induce HR-associated cell death in non-host tomato cells.

Effect of methyl jasmonate on harpin-induced hypersensitive cell death, generation of hydrogen peroxide and expression of PAL mRNA in tobacco suspension cultured BY-2 cells

Methyl jasmonate inhibited the harpin-induced defense responses such as cell death, H2O2 generation and gene expression encoding phenylalanine ammonia-lyase in tobacco suspension cultured BY-2 cells. These results suggest that MeJA may act as an endogenous suppressor for plant defense response including hypersensitive reaction.

Neurovirulence in mice of soluble receptor-resistant (srr) mutants of mouse hepatitis virus: intensive apoptosis caused by less virulent srr mutant

Three soluble receptor-resistant (srr) mutants, srr7, srr11 and srr18, derived from a highly neurotropic mouse hepatitis virus (MHV) JHMV have a single amino acid mutation in the spike (S) protein. We examined using ICR mice whether the amino acids mutated in the mutants were involved in the neurovirulence. Srr7 showed apparently reduced neurovirulence relative to the wild-type (wt) JHMV in terms of the LD50 and survival time, while the others showed slightly reduced virulence. In the brain and spinal cord, the growth of srr7 was more than 2 log10 lower than that of the wt virus. Histopathologically, no significant difference was revealed between wt and srr7-infected mice on day 2 postinoculation (p.i.), with only scant inflammation and a minimum degree of neuropathological changes. The major difference was that apoptotic cells were frequently encountered in the srr7-infected mouse brain, but not in wt-infected mice on day 2 p.i. However, there was no difference between these viruses in the potential to induce apoptosis in cultured cells. The apoptosis in the brain did not appear to result from the direct viral attack, since apoptotic cells were found in the lesion where viral antigens were barely detected. The present study suggests that the amino acids mutated in the S protein of srr mutants, especially the amino acid at position 1114 mutated in srr7, influence the neurovirulence in mice.

Protective effects of murine recombinant interferon-beta administered by intravenous, intramuscular or subcutaneous route on mouse hepatitis virus infection

The significance of the route for administration of murine recombinant interferon-beta (IFN-beta) for inducing its therapeutic effects has been studied. BALB/c mice were daily injected intravenously, intramuscularly or subcutaneously with 1.5x10(3), 1. 5x10(4), or 1.5x10(5) IU of IFN-beta, from one day before to 8th day after mouse hepatitis virus (MHV-2) challenge. All mice received IFN-beta survived significantly longer than those without IFN. In the liver of those IFN-treated mice, viral growth and the histopathological damages were extremely alleviated. These results suggest that, irrespective of the differences in the route of administration, IFN-beta markedly suppressed viral activity when its administration was started prior to viral infection. For clinical use, however, further studies are needed on the optimal route for administration if IFN-beta is given after viral infection.

Impaired entry of soluble receptor-resistant mutants of mouse hepatitis virus into cells expressing MHVR2 receptor

Mouse hepatitis virus (MHV) JHMV and its soluble receptor-resistant (srr) mutants, srr7, srr11, and srr18, grew and induced syncytia equally well in BHK-R1 cells expressing the MHVR1 receptor derived from MHV-susceptible BALB/c mice. In contrast, srr growth and syncytia formations were drastically reduced relative to wild-type (wt) virus in BHK-R2 cells expressing the MHVR2 receptor from MHV-resistant SJL mice. Infections by these srr mutants in BHK-R2 cells were 0.7 to 1.5 log10 less efficient than those of wt virus. BHK cells expressing both MHVR1 and MHVR2 supported srr replication to the same extent as did BHK-R1 cells, suggesting that inefficient infection by srr mutants in BHK-R2 cells resulted from the absence of the effective receptor MHVR1. Virus-receptor binding tests failed to demonstrate a difference between the abilities of wt and srr18 to bind MHVR2. The binding of srr7 and srr11 to both MHVR1 and MHVR2 was revealed lower by two- to fourfold relative to the wt binding. The fusion activity of srr S proteins as examined by the expression with recombinant vaccinia virus was apparently lower than that of the wt S protein in BHK-R2 cells, while there was not such a remarkable difference in BHK-R1 cells. This suggests that the most likely reason for inefficient infection by mutants in BHK-R2 is impaired virus entry into cells. These observations suggest that inefficient infections in BHK-R2 cells by srr mutants occur in the absence of a functional receptor MHVR1, which plays an important role in srr entry into cells.

Unique N-linked glycosylation of murine coronavirus MHV-2 membrane protein at the conserved O-linked glycosylation site

The membrane (M) proteins of murine coronavirus (MHV) strains have been reported to contain only O-linked oligosaccharides. The predicted O-glycosylation site consisting of four amino acid residues of Ser-Ser-Thr-Thr is located immediately adjacent to the initiator Met and is well conserved among MHV strains investigated so far. We analyzed the nucleotide sequence of a highly virulent strain MHV-2 M-coding region and demonstrated that MHV-2 had a unique amino acid, Asn, at position 2 at the conserved O-glycosylation site. We also demonstrated that this substitution added N-linked glycans to MHV-2 M protein resulting in increment of molecular mass of MHV-2 M protein compared with JHM strain having only O-linked glycans.

Type A behavior is associated with an increased risk of left ventricular hypertrophy in male patients with essential hypertension

OBJECTIVE

To determine whether type A behavior, which is associated with a risk of coronary heart disease, affects left ventricular hypertrophy in patients with essential hypertension.

DESIGN

Cross-sectional study of 88 untreated patients with mild to moderate essential hypertension (33 men, mean +/- SEM age 54 +/- 1 years).

METHODS

We measured the type A behavior score using a standardized questionnaire, left ventricular mass index using M-mode echocardiography and 24 h mean ambulatory blood pressure (recorded every 30 min). Beat-to-beat blood pressure was also measured using a Finapres device in patients at rest and during mental stress (counting backward) to determine the blood pressure response to stress.

RESULTS

The left ventricular mass index was correlated with the type A behavior score (r = 0.214, P < 0.05), age (r = 0.266, P < 0.05), 24 h mean systolic and diastolic blood pressures (r = 0.391, P < 0.001, and r = 0.382, P < 0.001, respectively), systolic blood pressure both at rest and during stress (r = 0.255, P < 0.05, and r = 0.215, P < 0.05, respectively), and the variability of both systolic and diastolic blood pressures at rest (r = 0.253, P < 0.05, and r = 0.321, P < 0.01, respectively). Stepwise multiple linear regression analysis demonstrated that age was associated with an increase in the left ventricular mass index for both sexes (P = 0.004 for males, P = 0.003 for females). The type A behavior score predicted a greater increase in left ventricular mass index in men (P = 0.018) but not in women. The 24 h mean systolic blood pressure was associated with a greater increase in left ventricular mass index in women (P < 0.001) but not in men.

CONCLUSION

Type A behavior is an independent risk factor for left ventricular hypertrophy in male patients with essential hypertension.

Difference in Bgp-independent fusion activity among mouse hepatitis viruses

Mouse hepatitis virus (MHV) utilizes a mouse biliary glycoprotein (Bgp) as a receptor. Co-cultivation of MHV-nonpermissive hamster BHK cells devoid of mouse Bgp with mouse DBT cells infected with MHV-A59 or JHMV induces syncytia formation on BHK cells (Bgp-independent fusion). This study shows the difference in Bgp-independent fusion activity among various MHV strains. Under a phase contrast microscopy, JHMV (cl-2, sp-4) induced the Bgp-independent syncytia on BHK cells similar to those observed on DBT cells, while such syncytia were not seen with the infection of other MHV strains (MHV-1, MHV-3, MHV-A59, MHV-S, srr7, srr11 and srr18). Tiny syncytia detectable only by immunofluorescence were produced with the latter MHV strains except for srr7 which failed to produce syncytia. MHVs except for srr7 grew in BHK cells after Bgp-independent infection. The Bgp-independent fusion by JHMV was inhibited either by anti-S1 or anti-S2 antibodies. These results showed that the JHMV spike protein had a remarkably high Bgp-independent fusion activity.

Differential receptor-functionality of the two distinct receptor proteins for mouse hepatitis virus

We compared the virus-binding activity and receptor-functionality of the receptor proteins isolated from mouse hepatitis virus (MHV)-susceptible BALB/c mice (MHVR1) and MHV-resistant SJL mice (MHVR2). By using a soluble receptor protein which lacked the transmembrane and intracytoplasmic domains, virus overlay protein blot assay and neutralization tests showed that MHVR1 bound to JHM cl-2 virus with 300-500 times higher efficiency than to MHVR2. MHVR1 was revealed to have 10-30 fold higher receptor-functionality than MHVR2 when examined by measuring virus-binding to the receptor expressed on the cell surface. These findings suggested that the differences in susceptibility between BALB/c and SJL mice may depend upon the genotype of the MHV receptor.

Isolation and characterization of murine coronavirus mutants resistant to neutralization by soluble receptors

Murine coronavirus mutants resistant to neutralization with soluble receptors were isolated to study the receptor-binding site on the S proteins since such mutants were expected to have mutations in an important site for receptor-binding. We have isolated five soluble receptor-resistant (srr) mutants which had mutations of a single amino acid at 3 different positions in S protein. Srr mutant 11 with an amino acid change at position 65 (Leu to His) in the S1 subunit showed an extremely reduced binding by virus overlay protein blot assay. However srr mutants with a mutation at 1114 (Leu to Phe) (srr mutants 3, 4 and 7) or 1163 (Cys to Phe) (srr mutant 18) in the S2 subunit had receptor-binding activity similar to that of wild type cl-2. These results suggest that an amino acid at position 62 located in a conserved region among MHV strains is in particular important for receptor binding. We also discuss why srr mutants with a mutation in S2 showed high resistance to neutralization by soluble receptor, irrespective of their binding to MHV receptors.

Requirement of proteolytic cleavage of the murine coronavirus MHV-2 spike protein for fusion activity

The spike (S) protein of a non-fusogenic murine coronavirus, MHV-2, was compared to that of a variant, MHV-2f, with fusion activity. Two amino acids differed between The S proteins of these viruses; one was located in the signal sequence (amino acid 12) and the other in the putative cleavage site (amino acid 757). To determine which one of these amino acid changes is important for the alteration of fusogenicity, chimeric S proteins between MHV-2 and -2f were constructed and expressed in DBT cells by a vaccinia virus expression system. The results revealed that one amino acid change (Ser to Arg) at position 757 is responsible for the acquisition of fusogenicity of the MHV-2f S protein. This change also altered the susceptibility to proteolytic cleavage of the MHV-2 S protein which was originally uncleavable. We concluded that the non-fusogenic activity of MHV-2 results from the lack of cleavage of its S protein.

Four geographically distinct genotypes of JC virus are prevalent in China and Mongolia: implications for the racial composition of modern China

JC polyomavirus (JCV) is ubiquitous in humans, persisting in renal tissue and excreting progeny in urine. It has been shown that the genotyping of urinary JCV offers a novel means of tracing human migrations. This approach was used to elucidate the racial composition of modern China. JCV isolates in the Old World were previously classified into nine distinct genotypes. One of them (B1) has a wide domain, encompassing part of Europe and the entirety of Asia. By constructing a neighbour-joining phylogenetic tree, all B1 isolates detected so far were classified into four distinct groups (B1-a to -d), each occupying unique domains in the world. According to this revised classification system of JCV DNAs, four genotypes (CY, SC, B1-a and -b) were found to be prevalent in China and Mongolia (Mongolia was studied instead of Inner Mongolia, which is part of China). There was a remarkable variation in the incidence of genotypes among the sites of sample collection. CY was more frequently detected in Northern China, SC was predominant in Southern China and B1-b was detected only in Mongolia. B1-a was spread throughout China. These data were statistically analysed and the observed regional differences in the incidence of genotypes were found to be significant. It is likely that these differences in JCV distribution in China reflect the intermingling of different population groups that constitute modern China.

Archetype JC virus efficiently replicates in COS-7 cells, simian cells constitutively expressing simian virus 40 T antigen

JC polyomavirus (JCV), the causative agent of progressive multifocal leukoencephalopathy (PML), is ubiquitous in humans, infecting children asymptomatically and then persisting in the kidney. Renal JCV is not latent but replicates to excrete progeny in the urine. The renal-urinary JCV DNAs carry the archetype regulatory region that generates various rearranged regulatory regions occurring in JCVs derived from the brains of PML patients. Tissue cultures that support the efficient growth of archetype JCV have not been reported. We studied whether archetype JCV could replicate in COS-7 cells, simian cells transformed with an origin-defective mutant of simian virus 40 (SV40). Efficient JCV replication, as detected by a hemagglutination assay, was observed in cultures transfected with five of the six archetype DNAs. The progeny JCVs could be passaged to fresh COS-7 cells. However, when the parental cells of COS-7 not expressing T antigen were transfected with archetype JCV DNAs, no viral replication was detected, indicating that SV40 T antigen is essential for the growth of JCV in COS-7 cells. The archetype regulatory region was conserved during viral growth in COS-7 cells, although a small proportion of JCV DNAs underwent rearrangements outside the regulatory region. We then attempted to recover archetype JCV from urine by viral culture in COS-7 cells. Efficient JCV production was observed in COS-7 cells infected with five of the six JCV-positive urine samples examined. Thus, COS-7 cells should be of use not only for the production of archetype JCV on a large scale but also for the isolation of archetype JCV from urine.

Psychobehavioral factors involved in the isolated office hypertension: comparison with stress-induced hypertension

OBJECTIVE

To investigate the psychobehavioral factors involved in the isolated clinic blood pressure elevation and hypertension induced by mental stress.

DESIGN AND METHODS

We studied 73 untreated patients with essential hypertension defined as World Health Organization stage I or II (28 men and 45 women, mean age 55 +/- 11 years). The amount of isolated clinic blood pressure elevation was examined in terms of the difference between clinic and daytime ambulatory blood pressures. Blood pressure (measured using a Finapres device) and R-R interval (measured electrocardiographically) were continuously monitored with subjects at rest and under mental stress (counting backward) to examine the cardiovascular response to the stress. Psychobehavioral characteristics such as anger, anxiety, tension, type A behavior pattern, and nervousness were evaluated and scored using structured interviews and self-reporting questionnaires.

RESULTS

The anger score was inversely correlated to the clinic-ambulatory blood pressure difference for the systolic (r = -0.308, P < 0.01) and diastolic (r = -0.233, P < 0.05) blood pressures. The score for type A behavior pattern tended to be inversely correlated to the clinic-ambulatory blood pressure difference for diastolic blood pressure (r = -0.209, P < 0.1). The nervousness score was positively correlated to stress-induced increase in the systolic (r = 0.249, P < 0.05) and diastolic (r = 0.232, P < 0.05) blood pressures. The clinic-ambulatory blood pressure difference was not related to the blood pressure rise induced by mental stress (r = 0.170 for systolic blood pressure; r = 0.112 for diastolic blood pressure).

CONCLUSION

The isolated clinic blood pressure elevation and hypertension due to mental stress were related to different psychobehavioral factors.

Identification of spike protein residues of murine coronavirus responsible for receptor-binding activity by use of soluble receptor-resistant mutants

We previously demonstrated by site-directed mutagenesis analysis that the amino acid residues at positions 62 and 214 to 216 in the N-terminal region of mouse hepatitis virus (MHV) spike (S) protein are important for receptor-binding activity (H. Suzuki and F. Taguchi, J. Virol. 70:2632-2636, 1996). To further identify the residues responsible for the activity, we isolated the mutant viruses that were not neutralized with the soluble form of MHV receptor proteins, since such mutants were expected to have mutations in amino acids responsible for receptor-binding activity. Five soluble-receptor-resistant (srr) mutants isolated had mutations in a single amino acid at three different positions: one was at position 65 (Leu to His) (srr11) in the S1 subunit and three were at position 1114 (Leu to Phe) (srr3, srr4, and srr7) and one was at position 1163 (Cys to Phe) (srr18) in the S2 subunit. The receptor-binding activity examined by a virus overlay protein blot assay and by a coimmunoprecipitation assay showed that srr11 S protein had extremely reduced binding activity, while the srr7 and srr18 proteins had binding activity similar to that of wild-type cl-2 protein. However, when cell surface receptors were used for the binding assay, all srr mutants showed activity similar to that of the wild type or only slightly reduced activity. These results, together with our previous observations, suggest that amino acids located at positions 62 to 65 of S1, a region conserved among the MHV strains examined, are important for receptor-binding activity. We also discuss the mechanism by which srr mutants with a mutation in S2 showed high resistance to neutralization by a soluble receptor, despite their sufficient level of binding to soluble receptors.

Mouse susceptibility to mouse hepatitis virus infection is linked to viral receptor genotype

We have reported that the receptor for mouse hepatitis virus (MHV) expressed in MHV-susceptible BALB/c mice (MHVR1) has 10 to 30 times the virus-binding activity of the MHV receptor expressed in MHV-resistant SJL mice (MHVR2) (N. Ohtsuka, Y. K. Yamada, and F. Taguchi, J. Gen. Virol. 77:1683-1992, 1996). This fact indicates the possibility that the difference in MHV susceptibility between BALB/c and SJL mice is determined by the virus-binding activity of the receptor. To test this possibility, we have examined MHV susceptibility in mice with the homozygous MHVR1 gene (R1/R1 genotype), mice with the MHVR1 and MHVR2 genes (R1/R2 genotype), and mice with the homozygous MHVR2 gene (R2/R2 genotype) produced by cross and backcross mating between BALB/c and SJL mice. All 63 F2 and backcrossed mice with the MHVR1 gene (R1/R1 and R1/R2) were susceptible to MHV infection, and all 57 with the homozygous MHVR2 gene (R2/R2) were resistant. We have also examined the MHV receptor genotypes of several mouse strains that were reported to be susceptible to MHV infection. All of those mice had the MHVR1 gene. These results suggest the possibility that the viral receptor determines the susceptibility of the whole animal to MHV infection.

Typing of urinary JC virus DNA offers a novel means of tracing human migrations

Although polyomavirus JC (JCV) is the proven pathogen of progressive multifocal leukoencephalopathy, the fatal demyelinating disease, this virus is ubiquitous as a usually harmless symbiote among human beings. JCV propagates in the adult kidney and excretes its progeny in urine, from which JCV DNA can readily be recovered. The main mode of transmission of JCV is from parents to children through long cohabitation. In this study, we collected a substantial number of urine samples from native inhabitants of 34 countries in Europe, Africa, and Asia. A 610-bp segment of JCV DNA was amplified from each urine sample, and its DNA sequence was determined. A worldwide phylogenetic tree subsequently constructed revealed the presence of nine subtypes including minor ones. Five subtypes (EU, Af2, B1, SC, and CY) occupied rather large territories that overlapped with each other at their boundaries. The entire Europe, northern Africa, and western Asia were the domain of EU, whereas the domain of Af2 included nearly all of Africa and southwestern Asia all the way to the northeastern edge of India. Partially overlapping domains in Asia were occupied by subtypes B1, SC, and CY. Of particular interest was the recovery of JCV subtypes in a pocket or pockets that were separated by great geographic distances from the main domains of those subtypes. Certain of these pockets can readily be explained by recent migrations of human populations carrying these subtypes. Overall, it appears that JCV genotyping promises to reveal previously unknown human migration routes: ancient as well as recent.

A novel method for isolation of Chlamydia pneumoniae by treatment with trypsin or EDTA

To establish a novel method for the efficient isolation of Chlamydia pneumoniae, experiments were performed to determine the effects of EDTA or trypsin treatment of C. pneumoniae on its adsorption and inclusion body formation. Treatment of C. pneumoniae with 0.1% trypsin or 1 mM EDTA significantly increased inclusion body-forming activity from 8,000- to 10,000-fold higher than that of the control. C. pneumoniae was successfully isolated in cultured cells which were inoculated with clinical specimens after treatment with 0.1% trypsin.

Analysis of bile acids in colon residual liquid or fecal material in patients with colorectal neoplasia and control subjects

Bile acids are believed to play a role in the etiology of colorectal cancer. To examine the relationship between bile acids and colorectal neoplasia, bile acids in colon residual liquid or fecal material were analyzed in 18 patients with colorectal adenoma, 12 patients with colorectal cancer, and 18 healthy control subjects. High-performance liquid chromatography combined with immobilized 3 alpha-hydroxysteroid dehydrogenase in column form showed a significant elevation in the proportion of deoxycholic acid (P < 0.05), lithocholic acid (P < 0.05), secondary bile acids (deoxycholic acid plus lithocholic acid) (P < 0.02), and the chenodeoxycholic acid-lithocholic acid family (chenodeoxycholic acid plus lithocholic acid) (P < 0.05) in the colon residual liquid or fecal material of the patients with colorectal adenoma compared with proportions in the control subjects. A similar trend was noted in the patients with colorectal cancer compared to the control subjects. These findings suggested that an increase in the proportion of secondary bile acids, in particular, of lithocholic acid, was closely related to the pathogenesis of colorectal neoplasia.

Persistent JC virus (JCV) infection is demonstrated by continuous shedding of the same JCV strains

The polyomavirus JC virus (JCV), the causative agent of progressive multifocal leukoencephalopathy, is ubiquitous in the human population, infecting children asymptomatically. JCV is often detected in normal renal tissue and in the urine of healthy individuals. We demonstrate that renal JCV represents that which persists after primary infection.

Significance of serum iron and ferritin in patients with colorectal adenomas

BACKGROUND

Colorectal adenomas are often detected on mass screening, although detection rates with fecal occult blood tests are low. The relationship between colorectal adenomas and the resulting blood loss was examined indirectly, using serum iron and ferritin levels.

METHODS

Serum iron and ferritin concentrations were measured in 184 men with colorectal adenomas (> or = 1 cm in 92; < 1 cm in 92) and in 92 healthy male controls. Values in the three groups were compared. In the patients with adenomas > or = 1 cm, serum iron and ferritin levels were compared on the basis of the site, number, histology, and degree of dysplasia of the adenoma.

RESULTS

The mean serum iron level was significantly lower in patients with adenomas > or = 1 cm than in controls (P < 0.05), although this level did not differ significantly between those with adenomas < 1 cm and controls. The mean serum ferritin level also was significantly lower in patients with adenomas > or = 1 cm than in those with adenomas < 1 cm and controls (P < 0.05, P < 0.01, respectively), although this level did not differ between those with adenomas < 1 cm and controls. There was no difference in mean serum iron or ferritin levels on the basis of the site, number, histology, or degree of dysplasia of the adenoma.

CONCLUSIONS

We conclude that decreased serum iron and ferritin levels are related only to adenoma size and that adenomas > or = 1 cm may bleed steadily, resulting in iron deficiency. However, low dietary intake of iron and fiber may be one of the causes of low serum iron and ferritin.

Acquired fusion activity of a murine coronavirus MHV-2 variant with mutations in the proteolytic cleavage site and the signal sequence of the S protein

The spike (S) protein of a nonfusogenic murine coronavirus, MHV-2, was compared to the S protein of a variant with fusion activity, MHV-2f. Two amino acids differed between the S proteins of these viruses; one was located in the signal sequence and the other was in the putative cleavage site. The amino acid at position 12 in the signal sequence was S in MHV-2 and C in MHV-2f. The amino acid sequence of the cleavage site of MHV-2 was HRARS, while that of MHV-2f was HRARR, showing one amino acid replacement at position 757. In DBT cells infected with MHV-2, the S protein was not cleaved, while the S protein of MHV-2f was cleaved. The S protein of MHV-2f expressed in a transient vaccinia virus expression system was cleaved and was fusogenic in contrast to the nonfusogenic activity of uncleaved MHV-2 S protein. Because the signal sequence is assumed to be removed from the mature S protein soon after synthesis, and because the S protein of MHV-2 was expressed on the cell surface in the same way as the S protein of MHV-2f, the difference in the signal sequence seemed to have had little effect on the transportation and the fusion activity of the S protein. These results showed that MHV-2 does not fuse cells due to the lack of cleavage of its S protein. This conclusion differs from studies on the activity of syncytium formation by the S proteins of fusogenic MHV-JHM and -A59 strains. Possible reasons for these differences in fusion activity are discussed.

[Simultaneous isolation of MRSA and Pseudomonas aeruginosa using a novel selective and differential PMAC agar]

PMAC agar, a novel, selective and differential medium has been developed and was subjected for evaluation of its selective and differential capability of methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa from other bacteria such as Bacillus, Micrococcus, Gram-negative bacteria and drug resistant ones. Growth of MRSA and P. aeruginosa on PMAC agar was facilitated and their colonies were easily differentiated. Colonies of MRSA after 24 approximately 48 h incubation at 35 degrees C were small (2 to 4 mm in diameter), smooth and egg-yolk reaction positive. On the other hand, P. aeruginosa with pigment production (pyocianin, fluorescin or pyomelanin) formed large (2.5 to 7.0 mm in diameter), brownish black or brown colonies with a creamy edge. PMAC agar did not allow to grow unwanted bacteria tested except certain species formerly classified to Pseudomonas such as Burkholderia and Stenotrophomonas. However multi-drug resistant strains such as Enterobacter cloacae, Serratia marcescens and Acinetobacter calcoaceticus formed extremely small colonies. PMAC agar is recommended as a novel, useful medium for isolation, differentiation and presumptive identification of MRSA and P. aeruginosa from clinical and environmental sources.

Difference in virus-binding activity of two distinct receptor proteins for mouse hepatitis virus

The receptor proteins, MHVR1 (Bgp C or splice variant of mmCGM1 containing two ectodomains) and MHVR2 (mmCGM2) have been reported to be functional receptors for MHV, although there was a significant difference in their virus-binding activity as determined by virus overlay protein blot assay (VOPBA). To compare the receptor function of these proteins, their virus-binding capacities were tested by using soluble forms of the proteins which lacked the transmembrane and intracytoplasmic domains. To estimate the amounts of these proteins expressed, an epitope of influenza HA protein, for which specific monoclonal antibody was available, was used as a tag. Recombinant soluble MHVR1 and MHVR2, expressed in RK 13 cells using recombinant vaccinia virus were secreted into the culture fluids of infected cells expressing these proteins. The inhibitory effect on virus infectivity of MHVR1 was shown to be about 500-fold higher than that of MHVR2. A similar disparity was observed in virus binding by VOPBA. These two proteins worked as functional receptors when they were expressed on resistant BHK-21 cells. However, the efficiency of MHV infection in BHK-21 cells expressing MHVR1 was about 30-fold higher, as compared with those expressing MHVR2. These data show that the receptor function of MHVR1 was significantly higher than that of MHVR2 and suggests that the difference in susceptibility between SJL and BALB/c mice might be due to the specific receptor protein expressed in those animals.

Geographical distribution of the human polyomavirus JC virus type A and B and isolation of a new type from Ghana

The JC polyomavirus (JCV) is ubiquitous in humans infecting children asymptomatically, then persisting in renal tissue. Since JCV DNA can be readily isolated from urine, it should be a useful tool with which to study the evolution of DNA viruses in humans. We showed that JCV DNA from the urine of Japanese, Taiwanese, Dutch and German patients can be classified into A and B types, based upon restriction fragment length polymorphisms (RFLPs). This work was extended in the present study. We established multiple JCV DNA clones from the UK, Spain, Italy, Sweden, South Korea, People's Republic of China, Malaysia, Indonesia, Mongolia, India, Sri Lanka, Saudi Arabia, Ethiopia, Kenya, Zambia, South Africa and Ghana. Using type-specific RFLPs, most clones except the four clones from Ghana were classified as either type A or B. We constructed a molecular phylogenetic tree for the Ghanaian clones and several representative type A and B clones. According to the phylogenetic tree, the Ghanaian clones constituted a major new group, tentatively named type C. From the findings presented here and elsewhere, the following conclusions were drawn: (i) type A is prevalent only in Europe; (ii) type B is found mainly in Asia and Africa; and (iii) type C is localized to part of Africa. Our findings should help to clarify how JCV evolved in humans.

Analysis of the receptor-binding site of murine coronavirus spike protein

It has been found that a domain composed of 330 amino acids of the N terminus of murine coronavirus spike protein [S1N(330)] is involved in receptor-binding activity (H. Kubo, Y.K. Yamada, and F. Taguchi, J. Virol. 68:5403-5410, 1994). To delineate the amino acid sequences involved in receptor-binding activity, we have compared the S1N(330) proteins of seven different mouse hepatitis virus MHV strains that are able to utilize the MHV receptor protein. Three conserved regions (sites I, II, and III) were found to consist of more than 10 identical amino acids, and they were analyzed for receptor-binding activity by site-directed mutagenesis. S1N(330) with a substitution at position 62 from the N terminus of S1 in region I and that with substitutions at positions 212, 214, and 216 in region II showed no receptor-binding activity. The S1N(330) mutants without receptor-binding activity were not able to prevent virus binding to the receptor. These results suggest that the receptor-binding site on S1N(330) is composed of regions located apart from each other in the protein's primary structure, in which Thr at position 62 as well as amino acids located at positions 212, 214, and 216 are particularly important.

Role of C5a-ase in group B streptococcal resistance to opsonophagocytic killing

Type III group B streptococci (GBS) can be subdivided into three subtypes, RDP III-1, III-2, and III-3, on the basis of numerical analysis of HindIII restriction endonuclease digestion patterns (HindIII RDP) with their chromosomal DNAs. In the present study, the effect of C5a on opsonophagocytic killing of a representative strain from each RDP type was investigated by using a novel optical method for determining opsonophagocytic killing, and the effect of C5a-ase treatment of C5a on opsonophagocytic killing was also investigated. Pre-stimulation of polymorphonuclear leukocytes (PMNs) with C5a significantly increased opsonophagocytic killing of all three strains. The increase in killing was abolished by pretreating the C5a with GBS that express C5a-ase, a treatment that also destroyed the chemoattractant activity of the C5a. The kinetics of killing of the RDP III-2 strain differed from those of the other two strains. The survival of the RDP III-2 bacteria continued to decline over the entire 60-min incubation of the opsonophagocytic assay when PMNs were prestimulated with C5a or with C5a that had been inactivated with GBS C5a-ase (dC5a). In contrast, killing of the RDP III-1 and III-3 strains almost ceased after 20 or 60 min when PMNs were prestimulated with dC5a or C5a, respectively. A difference in bacterial killing between the III-2 strain and the III-1 and III-3 strains therefore became increasingly apparent with prolonged incubation time. The percentage of bacteria surviving in the extracellular fluid was approximately the same as the percentages of bacteria surviving in both intracellular and extracellular locations when PMNs were prestimulated with either C5a or dC5a. These data imply that the majority of bacterial killing occurred following phagocytosis and suggest that the enhanced killing of GBS following prestimulation of PMNs with C5a resulted from increased ingestion of the bacteria.

[Analysis of duodenal bile acids in patients with colorectal tumors and control subjects]

Bile acids are believed to play a role in the etiology of colorectal cancer. To investigate a possible relationship between bile acids and colorectal tumors, duodenal bile acids were analyzed in 18 patients with colorectal adenomas, 18 patients with colorectal carcinoma and 18 control subjects. Using high performance liquid chromatography and immobilized 3 alpha-hydroxysteroid dehydrogenase in column form, significant increases in the proportion of chenodeoxycholic acid and significant decreases in the proportion of deoxycholic acid and lithocholic acid were found in the bile of patients with colorectal adenoma or carcinoma compared with the control subjects. The data support the concept that bile acids have a role to play in the development of large bowel tumors.

The S2 subunit of the murine coronavirus spike protein is not involved in receptor binding

The receptor-binding capacity of the S2 subunit of the murine coronavirus S protein was examined by testing the inhibition of virus-receptor binding. Sp-4 virus and S1N(330), which consists of the N-terminal 330 amino acids of the S1 protein, both of which exhibited receptor-binding capacity, were able to prevent the binding of cl-2 virus to the receptor, while the mutant protein S1N(330)-159, which failed to bind to the receptor protein, and S2TM-, which lacks the transmembrane and cytoplasmic domains normally existing in the S2, were unable to prevent the binding of cl-2. By using cultured DBT cells, it was revealed that the infection of cells by cl-2 virus was significantly inhibited by S1N(330) but not by S2TM-. These results indicate that the S2 protein is not involved in the receptor binding of murine coronaviruses.

Rapid detection of Vibrio cholerae with a new selective enrichment medium and polymerase chain reaction

The inhibitory effect of metallic EDTA compounds on growth of Vibrio cholerae and Escherichia coli was studied. Only Fe-EDTA among the compounds tested showed pH-dependent growth inhibition on E. coli at pH 9.0, but no inhibition of V. cholerae at the same pH. By addition of Fe-EDTA as a selective inhibitor, a novel enrichment broth (tentatively designated as VCF broth) for the selective isolation and cultivation of V. cholerae from other Gram-negative bacilli has been developed, and the selective enrichment capacity of VCF broth for V. cholerae and selective inhibiting activity against E. coli were significantly higher than those of alkaline peptone water. A simple procedure for rapid detection of V. cholerae by selective enrichment for 6 hr with VCF broth and then amplification of the cholera toxin target DNA fragment by the polymerase chain reaction was presented. VCF broth may be a useful tool for the selective enrichment of V. cholerae in bacterial examinations.