Development of a novel matrix-assisted laser desorption/ionization time-of-flight mass spectrum (MALDI-TOF-MS)-based typing method to identify meticillin-resistant Staphylococcus aureus clones

BACKGROUND

Mass spectrum analysis enables species- and subspecies-level identification, and can be used as an epidemiological tool in outbreak management. However, its reliability at clonal level has yet to be established.

AIM

To establish a matrix-assisted laser desorption/ionization time-of-flight mass-spectrum-based method that enables bacterial clone identification with accuracy equivalent to pulsed-field gel electrophoresis/phage open-reading frame typing (PFGE/POT).

METHODS

Meticillin-resistant Staphylococcus aureus (MRSA) was used in this study. Mass spectra were obtained from a standard strain of S. aureus (ATCC29213) and 57 clinically isolated strains, categorized according to POT. Peaks associated with MRSA clone identification (N = 67) were extracted. Based on this peak information, the feasibility of MRSA clone identification was examined by cluster analysis.

FINDINGS

In addition to the 58 strains used for peak extraction, mass spectrum analysis of 24 clinically isolated outbreak strains revealed that peak data could be used for successful identification of clones. These typing results were fully consistent with the PFGE and POT results.

CONCLUSION

This novel method enables simple and rapid typing with accuracy equivalent to PFGE/POT. This method would be suited to rapid outbreak analysis, offering accurate information to combat infectious diseases.

Dental caries area of rat molar expanded by cigarette smoke exposure

OBJECTIVES

Passive smoking is the involuntary inhalation of cigarette smoke (CS) and has an adverse impact on oral health. We examined the effect of CS exposure on caries risk and experimental dental caries.

METHODS

Experimental dental caries was induced in rat maxillary molars which were inoculated orally with Streptococcus mutans MT8148 and maintained on a cariogenic diet (diet 2000) and high sucrose water during the experimental period. CS-exposed rats were intermittently housed in an animal chamber with whole-body exposure to CS until killed. Whole saliva was collected before CS exposure (day 0) and for 30 days after the start of CS exposure. Saliva secretion was stimulated by administration of isoproterenol and pilocarpine after anesthesia. Maxillary molars were harvested on day 31.

RESULTS

The increase in body weight of the CS-exposed rats was less than that of the control rats. Salivary flow rate, concentration of S. mutans in the stimulated saliva and caries activity score did not significantly differ between 0 and 30 days after the start of CS exposure. Histological examination of the caries-affected area on maxillary molars 30 days after CS exposure showed expansion compared to control rats. In the electron probe microanalysis, no differences were observed between the mineral components of the CS-exposed teeth and the control teeth.

CONCLUSION

These results suggest that CS exposure expands the caries-affected area in the maxillary molars of the rat.

Tem Study of Cvd‐Grown Bi‐Sr‐Ca‐Cu‐0 Thin Films on (001) Mgo Substrates

CVD‐grown Bi‐Sr‐Ca‐Cu‐0 thin films on (OOl)MgO with T at 110 K have been investigated by transmission electron microscopy. The films are found to consist of large domains oriented along the c‐axis, with diameters of 15‐100 um. These domains exhibit incommensurate superstructures along the fa‐axis. In addition, we have observed similar superstructure spots in two equivalent directions normal to each other. It has also been found that the interface between the thin film and the substrate is very abrupt. Five different perovskite‐related layers along the c‐axis with different thickness are present. In the thin film, 80K phases are dominant and 110 K phases are less likely. Three other phases are very rarely observed. Furthermore, boundaries where the layered structure is different on both sides are often found.

Cellular locations of proteinases and association with vesicles in Porphyromonas gingivalis

We found that locations of arginine-specific gingipain (RGP) in the cellular fractions in the crude extract, envelope, vesicles, and culture supernatants were 48%, 16%, 17%, and 31%, respectively, and the corresponding values of lysine-specific gingipain (KGP) were 47%, 10%, 7%, and 36%, respectively. Although the molecular mass of RGP in the culture supernatant had been determined as 43 kDa, and that of KGP had been as 48 kDa, molecular masses of both proteinases solubilized from the vesicles were estimated to be over 1,500 kDa, since they eluted in the void volume of the column in the gel filtration on Sephacryl S-300. There was no reduction of molecular size by the following treatment with SDS, high-concentration NaCl, or urea. Interestingly, the occurrence of the macromolecular forms could not observed in other enzymes tested such as monopeptidyl, dipeptidyl, and tripeptidyl peptidases, as well as alkaline phosphatase. Therefore, occurrence of the macromolecular forms may be restricted to the proteinases. When the vesicle and culture supernatants containing free RGP and KGP were mixed and incubated, neither RGP nor KGP seemed to bind to vesicles. RGP bound to the vesicle was found to be more stable to heat treatment than the free form, suggesting that association of RGP with the vesicle caused heat stability of this enzyme.

Hemoglobin binding activity and hemoglobin-binding protein of Prevotella nigrescens

Prevotella nigrescens, lacking siderophores was found to bind to the hemoproteins. The binding was observed also in the envelope which was prepared by sonication of the cell. The binding occurred in the pH-dependent manner; the binding was observed below neutral pHs of the incubation mixtures but only slightly observed in the neutral and alkaline pHs. Furthermore, hemoglobin bound to the envelope was dissociated at high pHs buffers. Maximum amounts of hemoglobin bound to 1 mg envelope was 51.2 μg. Kd for the reaction at pH 5.0 was 2.1 × 10^-10M (210 pM). From the dot blot assay, hemoglobin could bind to a protein solubilized from the envelope by a detergent, referred to as hemoglobin-binding protein (HbBP), then it was purified by the sequential procedures of ion exchange chromatography, affinity chromatography and isoelectric focusing. Molecular weight and isoelectric point of the HbBP were 46 kDa and 6.1, respectively.

Porphyromonas gingivalis mutant defective in a putative extracytoplasmic function sigma factor shows a mutator phenotype

INTRODUCTION

Porphyromonas gingivalis is implicated as a major pathogen in the development and progression of chronic periodontitis. P. gingivalis must possess the ability to tolerate stress signals outside the cytoplasmic membrane by transcriptional activation of genes encoding proteins involved in defense or repair processes. Some bacteria utilize a distinct subfamily of sigma factors to regulate extracytoplasmic function (hence termed the ECF subfamily).

METHODS

To elucidate their role in P. gingivalis, a chromosomal mutant carrying a disruption of an ECF sigma factor PG1318-encoding gene was constructed. Hemagglutination and proteolytic activities were measured in the PG1318-defective mutant. Reverse transcription-polymerase chain reaction (RT-PCR) analysis and southern blot analysis were used to assess transcription of kgp in the PG1318-defective mutant. Frequency of spontaneous mutation that conferred resistance to l-trifluoromethionine was measured in the PG1318-defective mutant.

RESULTS

The PG1318-defective mutant formed non-pigmented colonies on blood agar plates at a relatively high frequency. Arginine-specific and lysine-specific proteinase activities of the non-pigmented variants were remarkably decreased compared with those of the parent strain and the pigmented variants. RT-PCR analysis showed that kgp was not transcribed in some non-pigmented variants and southern blot analysis revealed that there was a deletion in their kgp region. Frequency of mutation conferring resistance to l-trifluoromethionine was significantly higher in the PG1318-defective mutant than in the wild-type.

CONCLUSION

These results suggest that PG1318 plays a role in the regulation of mutation frequency in the bacterium.

Inorganic polyphosphate: a possible stimulant of bone formation

Inorganic polyphosphates [Poly(P)] are often distributed in osteoblasts. We undertook the present study to verify the hypothesis that Poly(P) stimulates osteoblasts and facilitates bone formation. The osteoblast-like cell line MC 3T3-E1 was cultured with Poly(P), and gene expression and potential mineralization were evaluated by reverse-transcription polymerase chain-reaction. Alkaline phosphatase activity, von Kossa staining, and resorption pit formation analyses were also determined. The potential role of Poly(P) in bone formation was assessed in a rat alveolar bone regeneration model. Poly(P) induced osteopontin, osteocalcin, collagen 1alpha, and osteoprotegerin expression and increased alkaline phosphatase activity in MC 3T3-E1 cells. Dentin slice pit formation decreased with mouse osteoblast and bone marrow macrophage co-cultivation in the presence of Poly(P). Promotion of alveolar bone regeneration was observed locally in Poly(P)-treated rats. These findings suggest that Poly(P) plays a role in osteoblastic differentiation, activation, and bone mineralization. Thus, local poly(P) delivery may have a therapeutic benefit in periodontal disease.

Dipeptidyl peptidase IV of Streptococcus anginosus: purification and characterization

We found that N-unblocked nine p-nitroanilde derivatives of amino acids or peptides were hydrolyzed by the crude cell extracts of Streptococcus anginosus NCTC 10713. Then dipeptidyl peptidase IV was purified 323-fold by the procedures including ammonium sulfate concentration, anion exchange chromatography (twice), gel filtration (twice), hydrophobic interaction chromatography, and isoelectric focusing. The molecular weight was calculated as 84 kDa, and the isoelectric point was 4.9. The enzyme hydrolyzed mainly dipeptides containing proline residues at P1 position. It was strongly inhibited by serine enzyme inhibitors. General protease inhibitors, metal chelators, thiol alkylating agent, reducing agent, and several metal ions had no effect on the enzyme activity. Optimum pH for the activity was found at 7.0. The enzyme was mostly inactivated by heating at 50 degrees C for 15 min.

[A successful management of acute myocardial infarction with severe left main trunk lesion using beating heart coronary artery bypass grafting: report of a case]

A 56-year-old male was admitted for sudden onset of severe chest pain and diagnosed as acute myocardial infarction (AMI). Emergency coronary angiography revealed complete obstruction of the left anterior descending artery (LAD) and 99% stenosis of left circumflex coronary artery (LCX), which was almost same with obstruction of the left main trunk coronary artery. Emergency coronary artery bypass grafting (CABG) to LAD and LCX was performed under a beating-heart. Left ventricular wall motion was improved after bypass grafting. CABG under a beating-heart is a new strategy for critical cases such as acute coronary syndrome. The better patency rate and the more complete revascularization that may be achieved with the new generation of stabilizers and retractors may improve long-term results.

Comparison of ability of apoptosis induction by lipopolysaccharide of Porphyromonas gingivalis with Escherichia coli

We compared effects of Porphyromonas gingivalis LPS with Escherichia coli LPS to the murine peritoneal macrophage. E. coli LPS possessed a threshold dose between 100 micro g and 10 micro g, the higher dose induced apoptosis at the murine peritoneal macrophage while the lower dose did not. The ability of apoptosis induction at the murine peritoneal macrophage of P. gingivalis LPS was weaker than E. coli LPS. P. gingivalis LPS did not induce significant apoptosis in all tested dose. However, the morphology of the peritoneal macrophage treated by P. gingivalis LPS was obviously different from that of the unstimulated cells.

Metabolism of 2-nitrofluorene, an environmental pollutant, by liver preparations of sea bream, Pagrus major

1. The in vitro metabolism of 2-nitrofluorene (NF), an environmental pollutant, was examined in fish, focusing on nitro-reduction followed by N-acylation and hydroxylation. 2. When NF was incubated with liver microsomes or cytosol of sea bream, Pagrus major, in the presence of NADPH or 2-hydroxypyrimidine, 2-aminofluorene (AF) was formed. 3. When AF was incubated with liver cytosol in the presence of acetyl-CoA or N-formyl-L-kynurenine, 2-acetylaminofluorene (AAF) or 2-formylaminofluorene (FAF) was formed, respectively. AAF and FAF thus formed were deacylated to the parent AF by the liver preparations. 4. AF, AAF and FAF were oxidized to 7-hydroxy or 5-hydroxy derivatives by the liver microsomes. 5. Nitro-reduction, N-acylation and ring-hydroxylation of NF and the metabolites were also observed in rat liver preparations. These activities in sea bream livers were lower than those of rat liver. However, the order of magnitude of these activities in fish was the same as in rat. 6. It is suggested that NF is effectively reduced to AF by the cytochrome P450 system or aldehyde oxidase, and the acylated metabolites, AAF and FAF, generated by arylamine acetyltransferase and formamidase were hydroxylated by the cytochrome P450 system in fish in the same way as in rat. Further, the acetylamino and formylamino derivatives were interconverted via amino derivatives in the fish.

Renal damage and salt-dependent hypertension in aged transgenic mice overexpressing endothelin-1

The recent development of endothelin-1 (ET-1) antagonists and their potential use in the treatment of human disease raises questions as to the role of ET-1 in the pathophysiology of such cardiovascular ailments as hypertension, heart failure, renal failure and atherosclerosis. It is still unclear, for example, whether activation of an endogenous ET-1 system is itself the primary cause of any of these ailments. In that context, the phenotypic manifestations of chronic ET-1 overproduction may provide clues about the tissues and systems affected by ET-1. We therefore established two lines of transgenic mice overexpressing the ET-1 gene under the direction of its own promoter. These mice exhibited low body weight, diminished fur density and two- to fourfold increases in the ET-1 levels measured in plasma, heart, kidney and aorta. There were no apparent histological abnormalities in the visceral organs of young (8 weeks old) transgenic mice, nor was their blood pressure elevated. In aged (12 months old) transgenic mice, however, renal manifestations, including prominent interstitial fibrosis, renal cysts, glomerulosclerosis and narrowing of arterioles, were detected. These pathological changes were accompanied by decreased creatinine clearance, elevated urinary protein excretion and salt-dependent hypertension. It thus appears that mild, chronic overproduction of ET-1 does not primarily cause hypertension but triggers damaging changes in the kidney which lead to the susceptibility to salt-induced hypertension.

A MATE family multidrug efflux transporter pumps out fluoroquinolones in Bacteroides thetaiotaomicron

We cloned a gene, bexA, that codes for a multidrug efflux transporter from the chromosomal DNA of Bacteroides thetaiotaomicron ATCC 29741 by using an Escherichia coli DeltaacrAB DeltaacrEF mutant as a host. Although the initial recombinant construct contained other open reading frames, the presence of bexA alone was sufficient to confer to the E. coli host elevated levels of resistance to norfloxacin, ciprofloxacin, and ethidium bromide. Disruption of bexA in B. thetaiotaomicron made the strain more susceptible to norfloxacin, ciprofloxacin, and ethidium bromide, showing that this gene is expressed in this organism and functions as a multidrug efflux pump. The deduced BexA protein sequence was homologous to the protein sequence of Vibrio parahaemolyticus NorM, a multidrug efflux transporter, and thus, BexA belongs to the multidrug and toxic compound extrusion (MATE) family.

Application of the piezo-micromanipulator for injection of embryonic stem cells into mouse blastocysts

Microinjection of embryonic stem (ES) cells into mouse blastocysts is one of the most important techniques for production of knockout or transgenic mice. However, skillful manipulation techniques and tremendous effort are required for this method. To overcome this difficulty, we applied a piezo-micromanipulator (PMM), which has been used for intracytoplasmic sperm injection in mice and production of cloned mice, for the injection of ES cells into blastocysts. When ES cells were injected by using a conventional method, 91% of the blastocysts were manipulated successfully. Using the PMM significantly (P < 0.01) increased the success rate of ES injection to 97%. The number of embryos manipulated in an hour increased from 9.7 embryos with the conventional method to 27.0 embryos with the PMM method. The injected ES cells did not show any detrimental effects due to a pulse from the PMM. After embryo transfer of the manipulated blastocysts, 39% of the newborns were chimeric mice with the conventional method, whereas 42% of the neonates were chimeric after the PMM method. These results indicate that microinjection of the ES cells into blastocysts is more efficient by the PMM method than the conventional method.

Alpha-tocopherol transfer protein is important for the normal development of placental labyrinthine trophoblasts in mice

Alpha-tocopherol transfer protein (alpha-TTP), a cytosolic protein that specifically binds alpha-tocopherol, is known as a product of the causative gene in patients with ataxia that is associated with vitamin E deficiency. Targeted disruption of the alpha-TTP gene revealed that alpha-tocopherol concentration in the circulation was regulated by alpha-TTP expression levels. Male alpha-TTP(-/-) mice were fertile; however, placentas of pregnant alpha-TTP(-/-) females were severely impaired with marked reduction of labyrinthine trophoblasts, and the embryos died at mid-gestation even when fertilized eggs of alpha-TTP(+/+) mice were transferred into alpha-TTP(-/-) recipients. The use of excess alpha-tocopherol or a synthetic antioxidant (BO-653) dietary supplement by alpha-TTP(-/-) females prevented placental failure and allowed full-term pregnancies. In alpha-TTP(+/+) animals, alpha-TTP gene expression was observed in the uterus, and its level transiently increased after implantation (4.5 days postcoitum). Our results suggest that oxidative stress in the labyrinth region of the placenta is protected by vitamin E during development and that in addition to the hepatic alpha-TTP, which governs plasma alpha-tocopherol level, the uterine alpha-TTP may also play an important role in supplying this vitamin.

Metabolism of 2-nitrofluorene, 2-aminofluorene and 2-acylaminofluorenes in rat and dog and the role of intestinal bacteria

1. The in vivo metabolism of 2-nitrofluorene (NF), an environmental pollutant, and 2-aminofluorene (AF) and its acylated derivatives, 2-formylaminofluorene (FAF) and 2-acetylaminofluorene (AAF), was examined in rat and dog. 2. 7-Hydroxy-2-nitrofluorene, 5-hydroxy-2-nitrofluorene, AF, AAF, FAF, 7-hydroxy-2-aminofluorene, 5-hydroxy-2-aminofluorene, 7-hydroxy-2-acetylaminofluorene, 5-hydroxy-2-acetylaminofluorene, 7-hydroxy-2-formylaminofluorene and 5-hydroxy-2-formylaminofluorene were identified as urinary and faecal metabolites of NF in rat and dog. 3. AAF and its hydroxylated derivatives were detected as major metabolites of NF in rat, but FAF and its hydroxylated metabolites were mainly excreted in dog. 4. AF, AAF, FAF and their hydroxylated metabolites were also identified as urinary and faecal metabolites of AF, AAF or FAF in rat, suggesting that AAF and FAF are interconverted via AF. 5. Treatment of rat and dog with antibiotics significantly decreased the urinary and faecal excretion of AF and its derivatives after oral administration of NF, and partly decreased the excretion of acylated metabolites after an oral dose of AF. 6. The caecal contents of untreated rats and some species of intestinal bacteria exhibited nitro-reductase activity toward NF, and acylating activity toward AF, affording AAF and FAF.

Mutagenicity of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) in the new gpt delta transgenic mouse

Gender differences and organ specificity of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mutagenesis were examined with the new gptdelta transgenic mouse (T. Nohmi, M. Katoh, H. Suzuki, M. Matsui, M. Yamada, M. Watanabe, M. Suzuki, N. Horiya, O. Ueda, T. Shibuya, H. Ikeda, T. Sofuni, A new transgenic mouse mutagenesis test system using Spi-and 6-thioguanine selections (Environ. Mol. Mutagen. 28 (1996) 465-470). In this mouse model, two distinct selections are employed to efficiently detect different types of mutations, i.e 6-thioguanine (6-TG) selection for point mutations and Spi-selection for deletions, respectively. In both selections, the highest mutant frequencies were observed in colon, followed by in spleen and liver. No increases in mutations were observed in testis, brain and bone marrow in PhIP-treated male mice. No significant differences in 6-TG and Spi- mutant frequencies were observed in colon and liver between male and female treated mice. The correlation between PhIP-induced mutagenesis and carcinogenesis in colon is discussed.

Transgenic mice with Alzheimer presenilin 1 mutations show accelerated neurodegeneration without amyloid plaque formation

Familial Alzheimer disease mutations of presenilin 1 (PS-1) enhance the generation of A beta1-42, indicating that PS-1 is involved in amyloidogenesis. However, PS-1 transgenic mice have failed to show amyloid plaques in their brains. Because PS-1 mutations facilitate apoptotic neuronal death in vitro, we did careful quantitative studies in PS-1 transgenic mice and found that neurodegeneration was significantly accelerated in mice older than 13 months (aged mice) with familial Alzheimer disease mutant PS-1, without amyloid plaque formation. However, there were significantly more neurons containing intracellularly deposited A beta42 in aged mutant transgenic mice. Our data indicate that the pathogenic role of the PS-1 mutation is upstream of the amyloid cascade.

Long lasting spasticity in controlled vasospastic angina

OBJECTIVE

To evaluate changes in coronary artery spasticity in patients with vasospastic angina who had been stable for years under continuous drug treatment.

METHODS

Follow up coronary angiography was performed under intracoronary ergonovine provocation in 27 well controlled patients with vasospastic angina and no organic stenosis; the tests were done > 24 months after the initial coronary angiography, in which occlusive spasm had been induced by the same regimen of ergonovine provocation.

RESULTS

The mean (SD) follow up period was 47.2 (21.6) months. All patients had been free from angina attack for more than 24 months under treatment with antianginal drugs. During this follow up period, organic stenosis developed in only one case. Occlusive spasm was observed during follow up coronary angiography in 23 patients. Spasm with 90% narrowing was observed in three other patients, and diffuse significant narrowing was seen in the final patient. No significant difference was found in spasticity (p = 0.75) between the initial and the follow up tests.

CONCLUSIONS

Repeated ergonovine provocation during coronary angiography after a controlled period of several years showed that coronary spasm remains inducible in most patients. Discontinuance of drug treatment during the remission from anginal attacks achieved by medication may put the patient at high risk.

Poly(ADP-ribose) polymerase gene disruption conferred mice resistant to streptozotocin-induced diabetes

Streptozotocin (STZ), a glucose analogue known to induce diabetes in experimental animals, causes DNA strand breaks and subsequent activation of poly(ADPribose) polymerase (Parp). Because Parp uses NAD as a substrate, extensive DNA damage will result in reduction of cellular NAD level. In fact, STZ induces NAD depletion and cell death in isolated pancreatic islets in vitro. Activation of Parp therefore is thought to play an important role in STZ-induced diabetes. In the present study, we established Parp-deficient (Parp-/-) mice by disrupting Parp exon 1 by using the homologous recombination technique. These mice were used to examine the possible involvement of Parp in STZ-induced beta-cell damage in vivo. The wild-type (Parp+/+) mice showed significant increases in blood glucose concentration from 129 mg/dl to 218, 370, 477, and 452 mg/dl on experimental days 1, 7, 21, and 60, respectively, after a single injection of 180 mg STZ/kg body weight. In contrast, the concentration of blood glucose in Parp-/- mice remained normal up to day 7, slightly increased on day 21, but returned to normal levels on day 60. STZ injection caused extensive necrosis in the islets of Parp+/+ mice on day 1, with subsequent progressive islet atrophy and loss of functional beta cells from day 7. In contrast, the extent of islet beta-cell death and dysfunction was markedly less in Parp-/- mice. Our findings clearly implicate Parp activation in islet beta-cell damage and glucose intolerance induced by STZ in vivo.

Accelerated rejection of Fas ligand-expressing heart grafts

The Fas/Fas ligand (FasL) system plays an important role in the induction of lymphoid apoptosis and has been implicated in the suppression of immune responses. Recently, there has been renewed interest in immune privilege, as it was shown that two privileged sites (the eye and testes) constitutively express FasL, which kills lymphoid cells that invade these areas. We have established murine FasL-transgenic mice (B6) under the control of the cardiac alpha-myosin heavy chain promotor, and transplanted FasL-expressing F1(B6 x C3H/HeJ) heart grafts into syngeneic (F1) and allogeneic (C3H/HeJ) recipients. FasL-expressing F1 heart allografts placed in C3H/HeJ recipients as well as FasL-expressing F1 isografts placed in nontransgenic and FasL-transgenic F1 were more rapidly rejected, and their survival was much shorter than that of nontransgenic control F1 allografts placed in C3H/HeJ. Native control and FasL-expressing hearts looked normal in mice up to 8 wk of age on hematoxylin-eosin staining. Control heart allografts undergoing ordinally acute rejection showed moderate focal lymphocyte infiltrates, while FasL-expressing F1 allografts and isografts showed massive hemorrhage, edema, and massive neutrophil infiltration as early as 1 day after transplantation. In conclusion, FasL expression and surgical procedure (ischemia/reperfusion) were synergistic in the induction of accelerated heart graft rejection, while allogenicity was not necessary. It may be necessary to find ways of controlling neutrophilic reaction/apoptosis in infiltrating lymphocytes to use FasL in clinical organ transplantation.

A genetic approach to visualization of multisynaptic neural pathways using plant lectin transgene

The wiring patterns among various types of neurons via specific synaptic connections are the basis of functional logic employed by the brain for information processing. This study introduces a powerful method of analyzing the neuronal connectivity patterns by delivering a tracer selectively to specific types of neurons while simultaneously transsynaptically labeling their target neurons. We developed a novel genetic approach introducing cDNA for a plant lectin, wheat germ agglutinin (WGA), as a transgene under the control of specific promoter elements. Using this method, we demonstrate three examples of visualization of specific transsynaptic neural pathways: the mouse cerebellar efferent pathways, the mouse olfactory pathways, and the Drosophila visual pathways. This strategy should greatly facilitate studies on the anatomical and functional organization of the developing and mature nervous system.

Spectra of gpt mutations in ethylnitrosourea-treated and untreated transgenic mice

We have established a new transgenic mouse mutagenicity assay for the efficient detection of point mutations and deletions in vivo (Nohmi et al. [1996] Env. Mol. Mutagen. 28:465-470). In this assay, the gpt gene of Escherichia coli is used as a reporter for the detection of point mutations. Treatment of mice with ethylnitrosourea (ENU, 150 mg/kg) enhances by several-fold the mutant frequency of gpt in bone marrow. Here, we report the mutation spectra of the gpt gene recovered from bone marrow of ENU-treated and untreated transgenic mice. In the gpt mutants rescued from ENU-treated mice, more than 90% of the mutations were base change mutations; the predominant types were A:T to T:A transversions and G:C to A:T transitions. On the contrary, in the mutants rescued from untreated mice, 54% were base substitutions and the remainders were short deletions and insertions. Among untreated mice, the most frequently observed base substitution was G:C to A:T transitions (7/14 mutants). Three of these occurred at 5'-CpG-3' sites. Interestingly, the mutation spectra of the gpt gene were different from those of the gpt gene in ENU-treated and untreated E.coli, whereas they were similar to those of the lacZ and lacI genes in ENU-treated and untreated other transgenic mice or cultured mammalian cells. We also report the establishment of homozygous transgenic mice that have transgene lambdaEG10 DNA in both chromosome 17 of C57BL/6J mouse.

Spi(-) selection: An efficient method to detect gamma-ray-induced deletions in transgenic mice

Despite the importance of genome rearrangement in the etiology of cancer and human genetic disease, deletion mutations are poorly detectable by transgenic rodent mutagenicity tests. To facilitate the detection and molecular analysis of deletion mutations in vivo, we established a transgenic mouse model harboring a lambdaEG10 shuttle vector that includes the red and gam genes for Spi(-) (sensitive to P2 interference) selection [Nohmi et al. (1996] Environ. Mol. Mutagen. 28:465-470]. This selection has a great advantage over other genetic systems, because phage deletion mutants can be preferentially selected as Spi(-) plaques, which can then be subjected to molecular analysis. Here, we show nucleotide sequences of 41 junctions of deletion mutations induced by gamma-irradiation. Unlike spontaneous deletion mutants, more than half of the large deletions occurred between short homologous sequences from one to eight bp. The remaining junctions had no such homologous sequences. Intriguingly, two Spi(-) mutants had P (palindrome)-like nucleotide additions at the breakpoints, which are frequently observed in the coding junctions of V(D)J recombination, suggesting that broken DNA molecules with hairpin structures can be intermediates in the repair of radiation-induced double-strand breaks. We conclude that Spi(-) selection is useful for the efficient detection of deletion mutations in vivo and that most rearrangements induced by gamma-rays in mice are mediated by illegitimate recombination through DNA end-joining.

Positive effect of partial zona-pellucida dissection on the in vitro fertilizing capacity of cryopreserved C57BL/6J transgenic mouse spermatozoa of low motility

Although cryopreservation of mouse spermatozoa has recently become available for use, as yet there are considerable differences in fertilization efficiency of cryopreserved spermatozoa among various mouse strains. In this study, oocytes subjected to partial dissection of the zona pellucida (PZD) were inseminated with frozen-thawed C57BL/6J mouse spermatozoa. At 30, 60, 120, and 240 min after insemination, the oocytes were washed in human tubal fluid medium and cultured for 3-6 h. The fertilization rates of the PZD oocytes in each group at 6-7 h after insemination were significantly higher than that of the zona-intact control (73-88% vs 12%, respectively) (p < 0.01); but the incidence of polyspermy was nevertheless quite low (1.3-2.4%). The development rates of the monospermic oocytes to the morula and early blastocyst stages were in the 87-92% range, with 31-40% of those developing into offspring after embryo transfer. When the cryopreserved spermatozoa of C57BL/6J transgenic mice were used to fertilize PZD oocytes, the fertilization rates were as high as (73-76%) those of the PZD oocytes inseminated with the cryopreserved C57BL/6J spermatozoa, with 30-31% of the morulae and early blastocysts derived from the monospermatic oocytes developing into offspring. These results indicate that PZD of oocytes may provide an alternative when the fertilizing capacity of mouse spermatozoa has been compromised by cryopreservation.

A role for macrophage scavenger receptors in atherosclerosis and susceptibility to infection

Macrophage type-I and type-II class-A scavenger receptors (MSR-A) are implicated in the pathological deposition of cholesterol during atherogenesis as a result of receptor-mediated uptake of modified low-density lipoproteins (mLDL). MSR-A can bind an extraordinarily wide range of ligands, including bacterial pathogens, and also mediates cation-independent macrophage adhesion in vitro. Here we show that targeted disruption of the MSR-A gene in mice results in a reduction in the size of atherosclerotic lesions in an animal deficient in apolipoprotein E. Macrophages from MSR-A-deficient mice show a marked decrease in mLDL uptake in vitro, whereas mLDL clearance from plasma occurs at a normal rate, indicating that there may be alternative mechanisms for removing mLDL from the circulation. In addition, MSR-A-knockout mice show an increased susceptibility to infection with Listeria monocytogenes or herpes simplex virus type-1, indicating that MSR-A may play a part in host defence against pathogens.

Therapeutic effect of cytomedicine on mesangio-proliferative glomerulonephritis in human interleukin-6 transgenic mice

We previously demonstrated that IgG1 plasmacytosis in human interleukin-6 transgenic mice (hIL-6 Tgm) was suppressed by the implantation of SK2 hybridoma cells (SK2 cells, which secrete anti-hIL-6 monoclonal antibodies) microencapsulated in a semipermeable and biocompatible device. In this study, we demonstrated that the mesangio-proliferative glomerulonephritis in hIL-6 Tgm was also improved by the same treatment. These results strongly support the concept of cytomedicine, which is a novel drug delivery system (DDS) using living cells. However, an electron microscopy study showed that cytomedicine has a limited duration of effectiveness because of the disappearance of space for cell proliferation in the microcapsule. Thus, the control of cell proliferation in a device must be developed to prolong the function and effectiveness of cytomedicine.

Cytomedical therapy for IgG1 plasmacytosis in human interleukin-6 transgenic mice using hybridoma cells microencapsulated in alginate-poly(L)lysine-alginate membrane

Cytomedical therapy for human interleukin-6 transgenic mice (hIL-6 Tgm) was implemented by the intraperitoneal injection of alginate-poly(L)lysine-alginate (APA) membranes microencapsulating SK2 hybridoma cells (APA-SK2 cells) which secrete anti-hIL-6 monoclonal antibodies (SK2 mAb). IgG1 plasmacytosis in the hIL-6 Tgm was suppressed by a single injection of APA-SK2 cells, and the survival time of these mice was remarkably prolonged. The viable cell number and the SK2 mAb-secretion of APA-SK2 cells increased for at least one month both under culture conditions and in allogeneic recipients (in vivo). Moreover, SK2 mAb which were secreted from APA-SK2 cells injected into allogeneic recipients was detected in serum at high concentrations; 3-5 mg/ml from day 14 to day 50 post-injection. In contrast, the injection of free SK2 cells had no therapeutic effect on hIL-6 Tgm. These results strongly suggest that APA membranes microencapsulating cells which were modified to secrete molecules useful for the treatment of a disorder were effective as an in vivo long-term delivery system of bioactive molecules, as 'cytomedicine'.

Germ-line contribution of embryonic stem cells in chimeric mice: influence of karyotype and in vitro differentiation ability

The effect of the karyotype and the ability to differentiate in vitro upon germ-line transmission by A3-1 embryonic stem (ES) cells in chimeric mice were examined. Germ-line transmission was confirmed in ES cells exhibiting 38% and more of the normal karyotype, but no chimeric mice and/or germ-line transmitters were observed regardless of the karyotype when the cystic embryoid body (CEB) was formed on day 8 and later in the suspension culture. Germ-line transmission of the ES cells was not significantly influenced by formation of the simple embryoid body (SEB). Germ-line transmitters were preferentially observed in chimeras when the ES cell contribution to coat color was markedly increased, but this contribution to coat color varied regardless of the karyotype or in vitro differentiation ability. These results suggest that A3-1 ES cells which exhibit CEB at 7 days after suspension culture and approximately 40% of normal karyotype are capable of germ-line transmission in chimeric mice.

Further metabolism of 2-formylaminofluorene, a metabolite of 2-aminofluorene, in rats

The further in vivo metabolism of 2-formylaminofluorene (FAF), which is a metabolite of 2-aminofluorene, was examined in rats. The 48 h urine collected following oral administration of FAF to rats was treated with beta-glucuronidase/arylsulfatase and extracted with benzene. When the benzene extract was subjected to HPLC, ten peaks due to FAF and its metabolites were detected. Among these metabolites, major metabolites 1, 2, 4 and 5 were isolated and identified unequivocally as 7-hydroxy-2-formylaminofluorene, 7-hydroxy-2-acetylaminofluorene, 5-hydroxy-2-formylaminofluorene and 5-hydroxy-2-acetylaminofluorene, respectively, by comparing their MS and UV spectra, and HPLC and TLC behavior with that of authentic specimens. Minor metabolites, 7-hydroxy-2-aminofluorene, 5-hydroxy-2-aminofluorene, 2-acetylaminofluorene and 2-aminofluorene together with the parent compound were detected by HPLC. These metabolites of FAF were also detected in the feces of rats given FAF.

A new transgenic mouse mutagenesis test system using Spi- and 6-thioguanine selections

A new transgenic mouse mutagenesis test system has been developed for the efficient detection of point mutations and deletion mutations in vivo. The mice carry lambda EG10 DNA as a transgene. When the rescued phages are infected into Escherichia coli YG6020-expressing Cre recombinase, the phage DNA is converted into plasmid pYG142 carrying the chloramphenicol-resistance gene and the gpt gene of E. coli. The gpt mutants can be positively detected as colonies arising on plates containing chloramphenicol and 6-thioguanine. The EG10 DNA carries a chi site along with the red and gam genes so that the wild-type phages display Spi- (sensitive to P2 interference) phenotype. Mutant phages lacking both red and gam genes can be positively detected as plaques that grow in P2 lysogens of E. coli. These mutant phages are called lambda Spi-. The spontaneous gpt mutation frequencies of five independent transgenic lines were 1.7 to 3.3 x 10(-5) in bone marrow. When the mice were treated with ethylnitrosourea (single i.p. treatments with 150 mg/kg body weight; killed 7 days after the treatments), mutation frequencies were increased four- to sevenfold over the background in bone marrow. The average rescue efficiencies were more than 200,000 chloramphenicol-resistant colonies per 7.5 micrograms bone marrow DNA per packaging reaction. In contrast to gpt mutation frequencies, spontaneous Spi- mutation frequencies were 1.4 x 10(-6) and 1.1 x 10(-6) in bone marrow and sperm, respectively. No spontaneous Spi- mutants have been detected so far in spleen, although 930,000 phages rescued from untreated mice were screened. In gamma-ray-treated animals, however, induction of Spi- mutations was clearly observed in spleen, at frequencies of 1.4 x 10(-5) (5 Gy), 1.2 x 10(-5) (10 Gy), and 2.0 x 10(-5) (5O Gy). These results suggest that the new transgenic mouse "gpt delta" could be useful for the efficient detection of point mutations and deletion mutations in vivo.

Pancreatic beta-cell-specific targeted disruption of glucokinase gene. Diabetes mellitus due to defective insulin secretion to glucose

Mice carrying a null mutation in the glucokinase (GK) gene in pancreatic beta-cells, but not in the liver, were generated by disrupting the beta-cell-specific exon. Heterozygous mutant mice showed early-onset mild diabetes due to impaired insulin-secretory response to glucose. Homozygotes showed severe diabetes shortly after birth and died within a week. GK-deficient islets isolated from homozygotes showed defective insulin secretion in response to glucose, while they responded to other secretagogues: almost normally to arginine and to some extent to sulfonylureas. These data provide the first direct proof that GK serves as a glucose sensor molecule for insulin secretion and plays a pivotal role in glucose homeostasis. GK-deficient mice serve as an animal model of the insulin-secretory defect in human non-insulin-dependent diabetes mellitus.

[Fate of two different stages of embryos transferred to an identical recipient in mice]

To define the developmental fate of two different stages of embryos existing together in the mouse reproductive tract, different stages of fresh and frozen-thawed embryos were transferred separately into the oviducts of identical recipients. ICR and FvB embryos were flushed from the oviducts and/or uterus of superovulated females on Day 1 (2-4-cell stage) and Day 2 (8-cell-morula stage) of pregnancy. Day 1 embryos were transferred separately to the right or left oviduct of recipients, while the other oviduct received Day 2 embryos. There were no significant differences between Day 1 and Day 2 embryos with respect to the number of implantation sites and live fetuses in either the fresh or frozen-thawed embryos. These results concerning to the embryonic stage were similar to those of control experiments, in which Day 1 or Day 2 embryos were transferred to both right and left oviducts of recipients. Furthermore, no strain differences were observed in this study. No developmental retardation or anomalies were observed in fetuses derived from either Day 1 or Day 2 embryos. The embryo transfer in this study revealed that differences in developmental stage at preimplantation were synchronized by the maternal uterine environment.

Production of mice entirely derived from embryonic stem (ES) cell with many passages by coculture of ES cells with cytochalasin B induced tetraploid embryos

Mice entirely derived from ES cells were obtained from aggregates of TT2 ES cells and cytochalasin B induced tetraploid embryos. Tetraploid embryos were cocultured with ES cells in a well on the Multiplate-Terasaki. After embryo transfer of the aggregates, the male newborns were recovered normally after Cesarean section and reached adulthood. The male mice exhibited complete pigmentation of the eye and coat, suggesting ES cell contributions alone. Alkaline phosphatase-1 analysis yielded no evidence of tetraploid cells in the kidney or liver. The TT2-derived males were fertile, produced normal offspring, and exclusively transmitted the TT2 genotype to their progeny. This result clearly shows that ES cells are able to support complete fetal development.

N-acetylation and N-formylation of carcinogenic arylamines and related compounds in dogs

When sulfanilamide, p-aminobenzoic acid, 4-amino-biphenyl, 2-aminofluorene or 1-aminopyrene was given orally to dogs, the corresponding N-acetyl and N-formyl derivates were isolated from urine or feces. These metabolites were identified unequivocally by comparison with an authentic sample by UV and mass spectrometry and their behaviour in TLC and HPLC. Dog intestinal flora and several bacterial strains exhibited both N-acetylating and N-formylating activities, in varying degrees, toward all of the arylamines tested. The metabolites formed by the intestinal bacteria were also isolated and identified unequivocally. The results suggest that the intestinal microflora plays an important role in the formation of N-acyl derivatives from arylamines in dogs.

[An application of in vitro fertilization--embryo culture--embryo transfer system on the drug safety evaluation: fertility test of male mice administered with the anticancer drug]

We examined an application of in vitro fertilization--embryo culture--embryo transfer system for reproductive and developmental study on the drug safety evaluation in mice. The male mice at 10 weeks of age were administered intravenously with a single dose of 75 mg/kg of the anticancer platinum complex (DWA 2114R) which inhibits DNA synthesis. Four to six weeks after administration, the males were mated with the superovulated females. Fertilization rates were significantly lower than the controls at each weeks after the administration. Furthermore, delayed formation of pronucleus was observed as compared with the control. Four weeks after administration, the preimplantation development to blastocyst stage of those embryos in vitro and the survival rates on the day 17 of gestation after embryo transfer suggested that a DNA synthesis in germ cells during maturation was inhibited and/or prevented by DWA 2114R. The results of in vitro fertilization reflected its sperm concentration rather than the administration of DWA 2114R. Thus, an analysis of the delayed formation of pronucleus observed fertilization in vivo could not done in detail. To use for the drug safety evaluation, there exist plenty of room for improvement in this system. These results have showed that the embryo culture and the embryo transfer are useful techniques as the reproductive and developmental study on the drug safety evaluation. These techniques bring additional informations on the pre- and post-implantation development in vivo.

[Lymphoid infiltration of colon cancer and clinical significance of the skin test]

It was reported that lymphoid infiltration (LI) of colon cancer tended to be found more commonly in patients with colonic cancer in an early stage than in an advanced stage. This time, the correlation among LI of colon cancer, cell-mediated immunity and the cumulative 5-year survival rate was studied in 124 patients with resected colon cancer. The results were as follows: 1) The cumulative 5-year survival rate in patients with positive LI was higher than that in the patients with negative LI. 2) There was correlation between the degree of LI of the cancer and Su-PS skin reaction. 3) Postoperative cell-mediated immunity was reduced in the cases of poor prognosis. Therefore we insist on paying attention to immunochemotherapy for 24 months after surgery.

[Intracoronary administration of ergonovine maleate for detecting vasospastic angina; one dose method]

Coronary spasm is an important etiologic mechanism in the pathogenesis of myocardial ischemia. Provocative test of coronary spasm during coronary arteriography is clinically useful. The ergonovine test has gained widespread use, and we have examined the efficacy and safety of intracoronary ergonovine application with a fixed dose of 16 micrograms. We studied 119 patients undergoing coronary arteriography. Coronary spasm was induced in 34 cases by intracoronary administration of 16 micrograms of ergonovine maleate. Coronary spasm was readily resolved by intracoronary administration of isosorbide dinitrate. None of the cases negative to the intracoronary ergonovine applications could be induced by additional systemic administration of 0.4 mg of ergonovine. Side effects of ergonovine such as elevation of blood pressure, headache and chest symptoms were infrequent in the intracoronary ergonovine test. We conclude that our method of intracoronary ergonovine application is sensitive and safe for the diagnosis of coronary spasm.

Percutaneous transluminal coronary angioplasty with cardiopulmonary bypass for stenosis of the most proximal part of the left anterior descending coronary artery

An 85 year old man with unstable angina pectoris was treated successfully with percutaneous transluminal coronary angioplasty supported by cardiopulmonary bypass and intra-aortic balloon pumping. Coronary angiography had shown stenoses in both the left main stem and left anterior descending coronary arteries. Drug treatment had been ineffective and he was too old for coronary arterial bypass grafting.

[Percutaneous transluminal angioplasty in patients with prior coronary artery bypass grafting]

Seventeen patients with stenosis of bypass grafts or native coronary arteries (NCA) following coronary artery bypass underwent percutaneous transluminal angioplasty (PTCA). Stenoses were located in the saphenous vein graft (SVG) in 11 cases (involving 16 lesions), in the internal mammary artery graft (IMAG) in 2 cases (2 lesions), and in the NCA in 9 cases (13 lesions). All patients had disabling angina pectoris or a post-operative stenosis of more than 50%. PTCA was successful in 75% of all the SVG stenotic lesions, 50% of the IMAG lesions and in 67% of the NCA lesions. There were no complications associated with PTCA. After successful PTCA, restenosis developed in 23% of the SVG cases, 0% of the IMAG cases and in 38% of the NCA cases. Though relief of chest pain was found in 10 patients (59%), PTCA of the NCA was not so effective as PTCA of the bypass grafts.

Angioscopy in transluminal balloon and laser angioplasty in the management of chronic hemodialysis fistulae

In chronic hemodialysis patients, there is the major problem of occlusion in the arteriovenous fistulae. To investigate this problem, the authors have developed angioscopy for examination and detection of occlusion developing to allow early use of transluminal balloon angioplasty (PTA) or laser angioplasty and prevent occlusions. The authors have examined 27 patients using a 2.7 mm diameter Olympus flexible angioscope and 9F sheath, following-up with a 4 mm balloon catheter (BARD) or SLT Nd-YAG laser. PTA was performed for 25 cases, with 19 demonstrating after one session patency lasting 9 months to date. Three cases revealed restenosis and have each received three PTA sessions. Laser angioplasty was performed in one case of 15 cm chronic occlusion, with subsequent PTA successfully enabling hemodialysis. Angioscopically, the authors were able to observe the various rest-forms within the shunt and detected the mural thrombus attached to the punctured pore. Both circumferential and valvular stenoses were observed. Initially after laser angioplasty, rough irregularity and a mural thrombus in the vessel was observed, but 2 months later, the vessel lumen had become smooth, probably due to intimal growth. Thrombus is acute stenosed cases were clearly observed. Angioplasty enabled new observations in the A-V fistulae, which allows investigation of the mechanism of stenosis or occlusion and enables an extended use of the hemodialysis blood access.

Scanning electron-microscopic studies on protein plugs obtained from patients with chronic pancreatitis

The previous histochemical study on the endoscopically obtained protein plugs revealed the process of protein plug formation. The present scanning electron-microscopic study was performed to clarify the fine structure of the protein plug and was quite in accordance with the results of the histochemical study: (1) protein plugs were constructed of interlacing networks and amorphous material stuffed in the networks; (2) protein plug formation started in the form of random and loose interlacing of cottony network fibrils and poor stuffing with degenerating epithelial cells and amorphous material, and in this stage protein plugs enlarged by adherence of smaller aggregates; (3) with maturation, protein plugs came to be covered by stratiform fine net works which were more compactly built up with uniformly thick, dense and smooth fibers and were stuffed more densely with amorphous material; (4) mature protein plugs were considered to enlarge by repeated process of stratiform deposit of reticular substance and amorphous material and subsequent maturation. However, it remains to be clarified which factors induce the changes of networks from random interlacing to stratiform arrangement.

Comparative studies on viscosity and concentration of protein and hexosamine in pure pancreatic juice

In order to investigate the cause of an increase in viscosity of pancreatic juice in patients with chronic pancreatitis, we performed comparative studies on voscosity and concentration of protein, hexosamine, three hydrolytic enzymes (amylase, chymotrypsinogen and lipase), calcium and gamma-Glutamyltranspeptidase in pure pancreatic juice. Pure pancreatic juice (PPJ) was obtained from seven control subjects, 10 patients with probable chronic pancreatitis and six patients with definite chronic pancreatitis by means of endoscopic retrograde catheterization of the papilla. Specimens were collected in ice-cooled tubes during the initial four-minute period and thereafter at two-minute intervals for 20 minutes after a rapid intravenous injection of secretin (Eisai Secrepan, 1 U/kg of body weight) and then at one-minute intervals for 10 minutes after a rapid intravenous injection of pancreozymin (Boots, 1 U/kg of body weight). It was demonstrated that the viscosity of PPJ was closely related to the concentration of hydrolytic enzyme protein, hexosamine and the presence of mucous substance and protein plugs.

Histochemical studies on protein plugs obtained by endoscopic retrograde catheterization of the papilla

In order to elucidate mechanisms of protein plug formation, histochemical studies were performed on aggregates and protein plugs present in pancreatic juice. Pancreatic juice was obtained from three control subjects and five patients with chronic pancreatitis through endoscopic retrograde catheterization of the papilla. Specimens for staining were prepared in two ways: (1) fixed with 10 per cent formaldehyde, embedded in paraffin and sectioned, and (2) placed on slide glass and fixed with isopropylalcohol. Staining included hematoxylin-eosin, periodic-acid Schiff, von Kossa, alcian blue, toluidine blue and double staining with PAS and AB. The process of protein plug formation can be as follows: (1) a prerequisite for aggregate formation, consisting of clusters of desquamated epithelial cells, highly concentrated sulfated acidic mucopolysaccharide and neutral mucopolysaccharide, (2) formation of aggregates in which epithelial cells and amorphous substance are interlaced with developing fine reticular substance, (3) enlargement of aggregates by fusion with adjacent aggregates through bridging action of the reticular substance sprouting, like prickles, from their surface, and (4) "maturity" of aggregates, taking a three-dimensional form which result in a spherical, spheroidal or cylindrical protein plug.