Two-Step Mechanism of Cyclin B Degradation Initiated by Proteolytic Cleavage with the 26 S Proteasome in Fish

To complete meiosis II, cyclin B is degraded in a short period by the inactivation of M-phase promoting factor (MPF). Previously, we showed that the destruction of cyclin B was initiated by the ubiquitin-independent proteolytic activity of the 26 S proteasome through an initial cut in the N-terminus of cyclin (at K57 in the case of goldfish cyclin B). We hypothesized that this cut allows cyclin to be ubiquitinated for further destruction by the ubiquitin-dependent proteolytic pathway, which leads to MPF inactivation. In this study, we aimed to identify the ubiquitination site for further degradation. The destruction of cyclin B point mutants in which lysine residues in a lysine-rich stretch following the cut site of cyclin B had been mutated was analyzed. All the lysine point mutants except K57R (a point mutant in which K57 was substituted with arginine) were susceptible to proteolytic cleavage by the 26 S proteasome. However, the degradation of the K77R and K7677R mutants in Xenopus egg extracts was significantly slower than the degradation of other mutants, and a 42 kDa truncated form of cyclin B was detected during the onset of the degradation of these mutants. The truncated form of recombinant cyclin B, an N-terminal truncated cyclin BΔ57 produced as cut by the 26 S proteasome, was not further cleaved by the 26 S proteasome but rather degraded in Xenopus egg extracts. The injection of the K57R, K77R and K7677R cyclin B proteins stopped cleavage in Xenopus embryos. From the results of a series of experiments, we concluded that cyclin B degradation involves a two-step mechanism initiated by initial ubiquitin-independent cleavage by the 26 S proteasome at lysine 57 followed by its ubiquitin-dependent destruction by the 26 S proteasome following ubiquitination at lysine 77.

Generation of Transparent Zebrafish with Fluorescent Ovaries: A Living Visible Model for Reproductive Biology

The transparent zebrafish enables researchers to study the morphology and distribution of cells and tissues in vivo. To capture the dynamic processes of germ cell proliferation and juvenile ovarian development in zebrafish in vivo, we established transgenic (TG) lines to allow us to monitor the changes in the ovaries of living fish. The original transgenic line with ovarian fluorescence was occasionally established. Although the cDNA integrated in the strain was constructed for the expression of enhanced green fluorescent protein (EGFP) driven by the medaka β-actin promoter, expression of EGFP is restricted to the oocytes and gills in adult fish. Mutant strains with transparent bodies, roy and ruby, were isolated in zebrafish. In this study, we crossed the TG strain with fluorescent ovary with transparent strains and established the TG (β-actin:EGFP);ruby strain. The strain is highly transparent, and the oocytes are easily observed in living fish. We identified a fluorescent tissue that might contain the undifferentiated germ cells close to the cloaca in the strain. This strain can be used for analysis of ovarian development in vivo.

Phosphate binders prevent phosphate-induced cellular senescence of vascular smooth muscle cells and vascular calcification in a modified, adenine-based uremic rat model

Clinical and experimental studies have reported that phosphate overload plays a central role in the pathogenesis of vascular calcification in chronic kidney disease. However, it remains undetermined whether phosphate induces cellular senescence during vascular calcification. We established a modified uremic rat model induced by a diet containing 0.3% adenine that showed more slowly progressive kidney failure, more robust vascular calcification, and longer survival than the conventional model (0.75% adenine). To determine the effect of phosphate on senescence of vascular smooth muscle cells (VSMCs) and the protective effect of phosphate binders, rats were divided into four groups: (1) normal control rats; (2) rats fed with the modified adenine-based diet (CKD); (3) CKD rats treated with 6% lanthanum carbonate (CKD-LaC); and (4) CKD rats treated with 6% calcium carbonate (CKD-CaC). After 8 weeks, CKD rats showed circumferential arterial medial calcification, which was inhibited in CKD-LaC and CKD-CaC rats. CKD rats showed increased protein expression of senescence-associated β-galactosidase, bone-related proteins, p16 and p21, and increased oxidative stress levels in the calcified area, which were inhibited by both phosphate binders. However, serum levels of oxidative stress and inflammatory markers, serum fibroblast growth factor 23, and aortic calcium content in CKD-CaC rats were higher than those in CKD-LaC rats. In conclusion, phosphate induces cellular senescence of VSMCs in the modified uremic rat model, and phosphate binders can prevent both cellular senescence and calcification of VSMCs via phosphate unloading. Our modified adenine-based uremic rat model is useful for evaluating uremia-related complications, including vascular calcification.

Properties of gene knockdown system by vector-based siRNA in zebrafish

RNA interference (RNAi) has emerged as a powerful tool to silence specific genes. Vector-based RNAi systems have been developed to downregulate targeted genes in a spatially and temporally regulated fashion both in vitro and in vivo. The zebrafish (Danio rerio) is a model animal that has been examined based on a wide variety of biological techniques, including embryonic manipulations, forward and reverse genetics, and molecular biology. However, a heritable and tissue-specific knockdown of gene expression has not yet been developed in zebrafish. We examined two types of vector, which produce small interfering RNA (siRNA), the direct effector in RNAi system; microRNA (miRNA) process mimicking vectors with a promoter for RNA polymerase II and short hairpin RNA (shRNA) expressing vector through a promoter for RNA polymerase III. Though gene-silencing phenotypes were not observed in the miRNA process mimicking vectors, the transgenic embryos of the second vector (Tg(zU6-shGFP)), shRNA expressing vector for enhanced green fluorescence protein, revealed knockdown of the targeted gene. Interestingly, only the embryos from Tg(zU6-shGFP) female but not from the male fish showed the downregulation. Comparison of the quantity of siRNA produced by each vector indicates that the vectors tested here induced siRNA, but at low levels barely sufficient to silence the targeted gene.

Characterization of multiple membrane progestin receptor (mPR) subtypes from the goldfish ovary and their roles in the induction of oocyte maturation

Oocyte maturation (OM) in goldfish is induced by the maturation inducing hormone (MIH) via its membrane receptor. Previously, we described the cloning of the membrane progesterone receptor alpha (mPRα or paqr7b) cDNA from a goldfish ovarian cDNA library and obtained experimental evidence that the mPRα protein is an intermediary in MIH induction of OM in goldfish. Three mPR subtypes have been identified in fish by cDNA cloning or by in silico analysis of genome sequence databases. In order to investigate the potential roles of the mPR subtypes in oocyte maturation, we cloned additional mPRs from a goldfish ovarian cDNA library. RACE amplification, and screening of the cDNA library identified one β (paqr8) and two γ subtypes (paqr5) (hereafter referred to as γ-1 and γ-2), respectively. Tissue distribution of mPR subtypes showed differential expression pattern. However, in addition to mPRα, the β, γ-1 and γ-2 subtypes were also expressed in follicle-enclosed oocytes. Cell lines expressing the β, γ-1 and γ-2 genes were established and their steroid binding properties compared. The β subtype exhibited higher binding affinity than the γ subtypes for 17,20β-DHP, the MIH in goldfish. Microinjection of goldfish oocytes with a morpholino antisense oligonucleotide to mPRβ blocked the induction of oocyte maturational competence, whereas injection of antisense oliogonucleotides to mPRγ-1 and γ-2 were ineffective. These results suggest that the goldfish mPRβ protein acts as an intermediary during MIH induction of OM in goldfish, in a manner similar to that described previously for mPRα.

In vivo induction of oocyte maturation and ovulation in zebrafish

The maturation of fish oocytes is a well-characterized system induced by progestins via non-genomic actions. In a previous study, we demonstrated that diethylstilbestrol (DES), a non-steroidal estrogen, induces fish oocyte maturation via the membrane progestin receptor (mPR). Here, we attempted to evaluate the effect of DES as an environmental endocrine disrupting chemical (EDC) upon fish oocyte maturation using live zebrafish. DES triggered oocyte maturation within several hours in vivo when administrated directly into the surrounding water. The natural teleost maturation-inducing hormone, 17alpha, 20beta-dihydroxy-4-pregnen-3-one (17,20beta-DHP) also induced oocyte maturation in vivo. Steroids such as testosterone, progesterone or 17alpha-hydroxyprogesterone were also effective in vivo. Further studies indicated that externally applied 17,20beta-DHP even induced ovulation. In contrast to 17,20beta -DHP, DES induced maturation but not ovulation. Theoretically this assay system provides a means to distinguish pathways involved in the induction of ovulation, which are known to be induced by genomic actions from the pathway normally involved in the induction of oocyte maturation, a typical non-genomic action-dependent pathway. In summary, we have demonstrated the effect of EDCs on fish oocyte maturation in vivo. To address the effects, we have explored a conceptually new approach to distinguish between the genomic and non-genomic actions induced by steroids. The assay can be applied to screens of progestin-like effects upon oocyte maturation and ovulation for small molecules of pharmacological agents or EDCs.

Superconductivity of κ-(BEDT–TTF)2 Cu[N(CN) 2]Br: Isotope Effect Revisited

In 1991, we reported a normal isotope effect in organic superconductor κ-(BEDT–TTF)2Cu[N(CN)2]Br, when all the hydrogen atoms of BEDT – TTF were replaced with deuterium. In other words, Tc was depressed by as much as 0.9 K, in contrast to the “inverse isotope effect” commonly observed in 10K-class organic superconductors. Recently, it was reported that the deuterated κ-(BEDT–TTF)2Cu[N(CN)2]Br shows an insulating nature when cooled very rapidly. Therefore, it is necessary for us to reexamine the superconducting transition of both deuterated and undeuterated κ- (BEDT – TTF)2Cu[N(CN)2]Br by SQUID measurements with special attention to the cooling speed. We studied the effect of cooling rate ranging from 10 K/min down to as slow as 0.02 K/min, and observed a significant effect not only on the superconducting transition temperature Tc but also on the superconducting volume fraction.

Survey of the levels of antimicrobial resistance in Argentina: WHONET program--1991 to 1994

The World Health Organization has implemented an international program of antibiotic resistance survey, called WHONET, with the participation of 121 laboratories from 41 countries around the world. Argentina joined WHONET program in 1989. Five hospitals from Buenos Aires are taking part, under the coordination of the National Institute of Microbiology 'Dr. C. Malbran'. From the results obtained between 1991 and 1994, the low level of susceptibility to aminopenicillins, cephalosporins and aminoglycosides is remarkable. On the other hand, vancomycin-resistant Enterococcus spp. and Staphylococcus spp. have not been detected and imipenem resistance in Pseudomonas aeruginosa, and Acinetobacter spp. isolates has not overcome 7% and 11%, respectively. Analytical programs utilizing these data aid in the understanding of the epidemiology of antibiotic resistance and in the development of rational antibiotic prescription practices and infection control procedures.

Sonophotocatalysis of endocrine-disrupting chemicals

Sonolysis and photolysis often exhibit synergistic effects in the degradation of organic molecules. An assay of fish oocyte maturation provides an appropriate experimental system to investigate the hormonal activities of chemical agents. Oocyte maturation in fish is triggered by maturation-inducing hormone (MIH), which acts on receptors on the oocyte surface. A synthetic estrogen, diethylstilbestrol (DES), possesses inducing activity of fish oocyte maturation, and a widely used biocide, pentachlorophenol (PCP), exhibits a potent inhibitory effect on fish oocyte maturation. In this study, the effects of the combined treatment by sonolysis with photolysis (sonophotocatalysis) to diminish the hormonal activity of DES and the maturation preventing activity of PCP was examined. By sonophotocatalysis, hormonal activity of DES was completely lost within 30 min and the inhibiting activity of PCP was lost within 120 min. These results demonstrated that sonophotocatalysis is effective for diminishing the endocrine-disrupting activity of chemical agents.

Two cases of calciphylaxis treated by parathyroidectomy: importance of increased bone formation

Calciphylaxis (calcific uremic arteriolopathy) is a poorly understood and highly morbid syndrome of both vascular calcification and skin necrosis. The main histopathological finding is calcium deposits within arteriolar and small vessel walls, showing endovascular fibrosis associated with fat necrosis. The therapeutic strategy is to normalize the high calcium-phosphate products (Ca x P). When calciphylaxis is complicated with advanced renal hyperparathyroidism (HPT), parathyroidectomy (PTX) should be performed promptly. However, for patients with low PTH level, calciphylaxis is unresponsive to PTX, and such an approach may worsen hyperphosphatemia and hypercalcemia. We report two patients with calciphylaxis confirmed by skin biopsy. PTX was performed in both patients based on high PTH levels. PTH and Ca x P level decreased in both patients post PTX. In Case 1, the skin ulcers gradually improved and almost disappeared after PTX. However, in Case 2, new ulcers appeared after PTX. In Case 1, alkaline phosphatase (ALP) after PTX was approximately twice its level before surgery and PTX resulted in normalization of uptake on bone scintigraphy. However, no rise in ALP was noted in Case 2, probably due to long-term use of aluminum, which prevented bone formation. These findings suggest that differences in the extent of bone formation explain the different response in post-PTX ulcer healing.

Interactions of diethylstilbestrol (DES) and DES analogs with membrane progestin receptor-alpha and the correlation with their nongenomic progestin activities

Progestin induction of oocyte maturation (OM) in fish is a useful model for investigating endocrine disruption of nongenomic steroid actions. Although diethylstilbestrol (DES) analogs have been shown to mimic the actions of progestins to induce meiotic maturation of goldfish and zebrafish oocytes, their molecular mechanisms of action remain unclear. The ability of these endocrine-disrupting chemicals (EDCs) to interact with the progestin receptor mediating OM was investigated in receptor binding assays using plasma membranes from goldfish ovaries and breast cancer cells transfected with goldfish membrane progestin receptor (mPR)-alpha. Membranes prepared from both ovaries and mPRalpha-transfected cells showed high-affinity, saturable, displaceable, single binding sites specific for the goldfish maturation-inducing steroid, 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20beta-DHP). DES and DES analogs (dipropionate-DES and hexestrol), which induce OM in goldfish, bound to the receptor and caused concentration-dependent displacement of [3H]-17,20beta-DHP, whereas dimethyl ether-DES had no affinity for the receptor. Scatchard plot analysis of specific 17,20beta-DHP binding in the presence of different amounts of DES showed that DES binding is of the noncompetitive type. The activities of DES and DES analogs to induce meiotic maturation of goldfish oocytes were examined in an in vitro bioassay. Whereas a concentration-dependent induction of OM was observed in response to DES, dipropionate-DES, and hexestrol, dimethyl ether-DES did not show any OM-inducing activity. The close correspondence between binding of DES and its analogs to the mPRalpha protein and their OM-inducing activities suggests a mechanism of endocrine disruption mediated by binding to mPRalpha resulting in its activation, thereby mimicking the nongenomic action of the progestin 17,20beta-DHP.

Vortex dynamics and the Fulde-Ferrell-Larkin-Ovchinnikov state in a magnetic-field-induced organic superconductor

Under special conditions, a superconducting state where the order parameter oscillates in real space, the so-called FFLO state, is theoretically predicted to exist near the upper critical field, as first proposed by Fulde and Ferrell, and Larkin and Ovchinnikov. We report systematic measurements of the interlayer resistance in high magnetic fields to 45 T in the two-dimensional magnetic-field-induced organic superconductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. The resistance is found to show characteristic dip structures in the superconducting state. The results are consistent with pinning interactions between the vortices penetrating the insulating layers and the order parameter of the FFLO state. This gives strong evidence for an oscillating order parameter in real space.

Candida glabrata fungemia in a diabetic patient with neurogenic bladder: successful treatment with micafungin

A 69-year-old man was transferred to our hospital because of fever and acute renal failure. 5 weeks prior to admission, he was admitted to another hospital and treated with several antibiotics including vancomycin, but fever did not subside and renal dysfunction showed rapid progression. On admission, laboratory findings revealed pyuria, inflammatory changes, acute renal failure, and disseminated intravascular coagulation (DIC). Computed tomography showed left ureteral stone and hydronephrosis. Gallium scintigraphy showed avid uptake in the left kidney. Serum concentration of vancomycin was 57.4 micro/ml. Candida glabrata was isolated from blood, sputum and urine. Under the diagnosis of fungemia and left pyelonephritis, he was treated with micafungin (150 mg/day), gabexate mesilate and insertion of a double-ended pigtail catheter. The above treatment produced regression of systemic inflammation, DIC and acute renal failure. At the last follow-up 3 weeks after discharge, ureteroscopy showed that the ureter stone had already passed but a soft white-yellowish bezoar was detected in the ureter. In this case, neurogenic bladder, poorly controlled diabetes, and long-term antibiotic treatment probably enhanced the development of C. glabrata infection. Antifungal treatment with micafungin is useful in patients with non-albicans Candida infection.

Molecular Cloning of cDNA Encoding APC11, a Catalytic Component of Anaphase-promoting-complex (APC/C), from Goldfish (Carassius auratus), and Establishment ofin vitroUbiquitinating System

Destruction of cyclin B is required for exit from mitosis and meiosis. A cyclin-degrading system, including anaphase-promoting-complex/cyclosome (APC/C), has been shown to be responsible for cyclin B destruction. Here we present the cloning, sequencing, and expression analysis of goldfish (Carassius auratus) APC11, which encodes the catalytic component of APC/C from goldfish ovary. The cloned cDNA is 348 bp long and encodes 88 amino acids. The deduced amino acid sequence is highly homologous to APC11 from other species. The expression of mRNA for APC11 was ubiquitous among tissues, as opposed to that of mRNA for E2-C, which occurred at a very high level in the ovary. Recombinant goldfish APC11 possesses ubiquitinating activity against cyclin B. We established an in vitro ubiquitinating system of proteins composed of purified recombinant E1, E2-C, and APC11 from goldfish. The reconstructed system for these ubiquitinating enzymes makes it feasible to elucidate the molecular mechanism of cyclin B degradation.

Persistent hyperparathyroidism in renal allograft recipients: vitamin D receptor, calcium-sensing receptor, and apoptosis

The phenotypic changes in parathyroid cells after successful renal transplantation remain to be elucidated. We compared 10 diffuse and 11 nodular hyperplastic parathyroid glands from five renal allograft recipients with persistent hyperparathyroidism, with five diffuse and 13 nodular hyperplasia from seven uremic patients on hemodialysis, and 13 normal glands. Comparisons included expressions of both vitamin D receptor (VDR) and calcium-sensing receptor (CaSR), proliferative activity (Ki67), and apoptosis (TUNEL). Immunoreactivity was assessed semiquantitatively and expressed as labeling index. The area/cell was also measured to assess cellular hypertrophy. The labeling indexes of VDR (587+/-71; mean+/-s.e.m.) and CaSR (45.0+/-2.8) in recipients' diffuse hyperplasia were significantly higher than those in uremic diffuse hyperplasia (224+/-44, 29.3+/-2.3, respectively) (P<0.01, each). However, these expressions remained low in recipients' nodular hyperplasia (42+/-8, 11.8+/-1.4, respectively). Ki67 labeling index in recipients' nodular hyperplasia (7+/-1) was significantly smaller than in uremic patients (24+/-6, P<0.01). TUNEL labeling index in recipients' diffuse hyperplasia (30+/-5) was the highest among the groups. The cell volume tended to be smaller in both patterns of hyperplasia in allograft recipients compared with uremic patients. Our results suggest that the phenotypic change in parathyroid cells after renal transplantation depends on the pattern of hyperplasia, where it is normalized only in diffuse hyperplastic glands in which the number of cells also regresses with significant induction of apoptosis.

Parathyroid growth and regression in experimental uremia

Early 1,25-dihydroxyvitamin D(3) (VD(3)) therapy during the course of renal failure prevents the downregulation of VD(3) receptor (VDR), calcium-sensing receptor (CaSR) or p21, and the parathyroid (PT) growth. We hypothesized that VD(3) could restore the decreased expressions of VDR and CaSR, and cause regression in enlarged PT glands. 5/6 nephrectomized rats fed high-phosphorus diet were killed at 1, 3, 5, or 7 days and at 2, 3, 4, 8, or 12 weeks. VD(3)-treated rats were given VD(3) intraperitoneally for 1, 2, 3, or 4 weeks, starting 8 weeks after 5/6 nephrectomy. PT glands were weighed and subjected to immunohistochemical analyses for VDR, CaSR, p21, Ki67, and Tdt-mediated dUTP nick end-labeling (TUNEL) assay. The area per cell was measured as the parameter of cell size. The expression of VDR and p21 began to decrease at day 1, and Ki67 increased at day 3, but decreased thereafter. There was a significant increase in PT gland weight to week 12 with the increase of cell size. VD(3) treatment significantly increased both VDR and CaSR expressions 2 weeks after the start of injection, and reduced the PT gland weight at week 3 with significant increase of TUNEL-positive cells and decrease of cell size. Our results suggest that PT growth in uremic rats involves both PT cell proliferation and hypertrophy, in association with the reduction of VDR, CaSR, and p21 expressions. In addition, VD(3) treatment could reverse PT hyperplasia and hypertrophy via restoration of these proteins.

Cloning and identification of a membrane progestin receptor in goldfish ovaries and evidence it is an intermediary in oocyte meiotic maturation

Previously, a cDNA clone encoding a protein that satisfies the criteria for its designation as a membrane progestin receptor, mPRalpha, was discovered in spotted seatrout ovaries. Moreover, preliminary evidence was obtained for a role for mPRalpha in maturation-inducing hormone (MIH) induction of oocyte maturation in this species. Here, we describe the cloning of the mPRalpha cDNA from a goldfish ovarian cDNA library. Northern blot analysis indicates the presence of a major 2.6kb transcript in ovaries that encodes a 354 amino acid protein which shows high sequence identity with seatrout (81%), zebrafish (93%), and human (55%) mPRalphas. Western blot analysis using a polyclonal goldfish mPRalpha antibody shows a major immunoreactive band of the predicted molecular weight (40kDa) in goldfish ovarian membranes. Computer modeling predicts that the deduced protein has seven transmembrane domains, typical of G protein-coupled receptors. Treatment of full grown, late vitellogenic stage follicle-enclosed oocytes in vitro with gonadotropin increased mPRalpha protein levels. A correlation between mPRalpha protein levels and the ability of oocytes to undergo GVBD in response to the MIH (maturational competence) was observed after treatment with gonadotropin. Microinjection of goldfish oocytes with a morpholino antisense oligonucleotide to mPRalpha blocked both the induction of oocyte maturational competence and mPRalpha protein upregulation by gonadotropin. These results with the goldfish mPRalpha protein are similar to those obtained previously with spotted seatrout, further supporting the hypothesis that the mPRalpha acts as an intermediary in MIH induction of oocyte maturation in teleosts.

Induction and inhibition of oocyte maturation by EDCs in zebrafish

BACKGROUND

Oocyte maturation in lower vertebrates is triggered by maturation-inducing hormone (MIH), which acts on unidentified receptors on the oocyte surface and induces the activation of maturation-promoting factor (MPF) in the oocyte cytoplasm. We previously described the induction of oocyte maturation in fish by an endocrine-disrupting chemical (EDC), diethylstilbestrol (DES), a nonsteroidal estrogen.

METHODS

In this study, stimulatory and inhibitory effects of EDCs and natural steroids on oocyte maturation were examined in zebrafish. For effective agents, some details about the mechanism in induction or inhibition of maturation were examined. Possible groups of DES interacting with the MIH receptor are discussed based on relative potency of steroids to induce maturation.

RESULTS

Among agents tested, tamoxifen (TAM) and its metabolite 4-hydroxytamoxifen (4-OHT) showed stimulatory activity similar to DES. The time courses of the change in germinal vesicle breakdown and an intracellular molecular event (the synthesis of cyclin B) induced by TAM were indistinguishable from those induced by MIH. In contrast, pentachlorophenol (PCP) had a potent inhibitory effect on MIH-induced oocyte maturation. PCP inhibited not only MIH-induced maturation but also DES- and TAM-induced maturation. Methoxychlor also inhibited maturation when oocytes were pre-treated with this agent.

CONCLUSION

These results suggest that EDCs act as agonists or antagonists in the induction of oocyte maturation in fish.

Ultrashort pulse-generation by saturable absorber mirrors based on polymer-embedded carbon nanotubes

We demonstrate passive mode locking of solid-state lasers by saturable absorbers based on carbon nanotubes (CNT). These novel absorbers are fabricated by spin-coating a polymer doped with CNTs onto commercial dielectric laser-mirrors. We obtain broadband artificial saturable absorber mirrors with ultrafast recovery times without the use of epitaxial growth techniques and the well-established spin-coating process allows the fabrication of devices based on a large variety of substrate materials. First results on passive mode locking of Nd:glass and Er/Yb:glass lasers are discussed. In the case of Er/Yb:glass we report the to our knowledge shortest pulse generated in a self-starting configuration based on Er/Yb:bulk-glass: 68 fs (45 fs Fourier-limit) at 1570 nm wavelength at a pulse-repetition rate of 85 MHz.

Identification of a protein kinase which phosphorylates a subunit of the 26S proteasome and changes in its activity during meiotic cell cycle in goldfish oocytes

The proteasome is involved in the progression of the meiotic cell cycle in fish oocytes. We reported that the alpha4 subunit of the 26S proteasome, which is a component of the outer rings of the 20S proteasome, is phosphorylated in immature oocytes and dephosphorylated in mature oocytes. To investigate the role of the phosphorylation, we purified the protein kinase from immature oocytes using a recombinant alpha4 subunit as substrate. A protein band which well corresponded to the kinase activity was identified as casein kinase Ialpha (CKIalpha). Two-dimensional (2D) PAGE analysis showed that part of the alpha4 subunit was phosphorylated by CKIalpha in vitro. This spot was detected in purified immature 26S proteasome but not in mature 26S proteasome, demonstrate that the alpha4 subunit is phosphorylated by CKIalpha meiotic cell cycle dependently.

Selective etching of metallic single-wall carbon nanotubes with hydrogen plasma

We present Raman scattering and scanning tunnelling microscopy (STM) measurements on hydrogen plasma etched single-wall carbon nanotubes (SWNTs). Interestingly, both the STM and Raman spectroscopy show that the metallic SWNTs are dramatically altered and highly defected by the plasma treatment. In addition, structural characterizations show that metal catalysts are detached from the ends of the SWNT bundles. For semiconducting SWNTs we observe no feature of defects or etching along the nanotubes. Raman spectra in the radial breathing mode region of plasma-treated SWNT material show that most of the tubes are semiconducting. These results show that hydrogen plasma treatment favours etching of metallic nanotubes over semiconducting ones and therefore could be used to tailor the electronic properties of SWNT raw materials.

Molecular cloning and expression of cDNA coding for four spliced isoforms of casein kinase Ialpha in goldfish oocytes

Casein kinase I (CKI) is a member of the serine/threonine protein kinases and located in a separate group within the superfamily of eukaryotic protein kinases. CKI isoforms regulate several checkpoints of the cell cycle and meiosis. In higher eukaryotes, CKIalpha has four isoforms produced through the alternative splicing of two short inserts. Here, we report the cloning, sequencing and expression of four alternatively spliced isoforms of CKIalpha from goldfish ovary. The cloned cDNAs were 2099-3002-bp long and classified as CKIalpha, CKIalphaS, CKIalphaL and CKIalphaLS. It was revealed that two major (3.0 and 2.0 kb) messages were strongly expressed in the ovary. Four isoforms are expressed in previtellogenic to vitellogenic oocytes. In the huge nucleus of the oocyte, referred to as the germinal vesicle, CKIalphaS is dominant and CKIalphaL is expressed at a detectable level. Immunoblot analysis revealed that CKIalpha and CKIalphaS are major products in both immature and mature oocytes. These two isoforms were expressed in a tissue-dependent manner.

Diethylstilbestrol induces fish oocyte maturation

An endocrine-disrupting chemical, diethylstilbestrol (DES), a nonsteroidal estrogen, triggers oocyte maturation in fish. The morphology (the time course of the change in germinal vesicle breakdown) and an intracellular molecular event (the de novo synthesis of cyclin B) induced by DES were indistinguishable from those induced by a natural maturation-inducing hormone, 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20beta-DHP). A synergistic action of DES on 17,20beta-DHP-induced oocyte maturation was observed. Both 17,20beta-DHP- and DES-induced oocyte maturation was inhibited by an antibody against the maturation-inducing hormone receptor. The structural requirement for the action of DES is discussed based on results obtained with DES analogs.

Regulated interaction between polypeptide chain elongation factor-1 complex with the 26S proteasome during Xenopus oocyte maturation

BACKGROUND

During Xenopus oocyte maturation, the amount of a 48 kDa protein detected in the 26S proteasome fraction (p48) decreased markedly during oocyte maturation to the low levels seen in unfertilized eggs. The results indicate that the interaction of at least one protein with the 26S proteasome changes during oocyte maturation and early development. An alteration in proteasome function may be important for the regulation of developmental events, such as the rapid cell cycle, in the early embryo. In this study, we identified p48.

RESULTS

p48 was purified by conventional column chromatography. The resulting purified fraction contained two other proteins with molecular masses of 30 (p30) and 37 (p37) kDa. cDNAs encode elongation factor-1gamma and delta were obtained by an immuno-screening method using polyclonal antibodies against purified p48 complex, which recognized p48 and p37. N-terminal amino acid sequence analysis of p30 revealed that it was identical to EF-1beta. To identify the p48 complex bound to the 26S proteasome as EF-1betagammadelta, antibodies were raised against the components of purified p48 complex. Recombinant EF-1 beta,gamma and delta were expressed in Escherichia coli, and an antibody was raised against purified recombinant EF-1gamma. Cross-reactivity of the antibodies toward the p48 complex and recombinant proteins showed it to be specific for each component. These results indicate that the p48 complex bound to the 26S proteasome is the EF-1 complex. MPF phosphorylated EF-1gamma was shown to bind to the 26S proteasome. When EF-1gamma is phosphorylated by MPF, the association is stabilized.

CONCLUSION

p48 bound to the 26S proteasome is identified as the EF-1gamma. EF-1 complex is associated with the 26S proteasome in Xenopus oocytes and the interaction is stabilized by MPF-mediated phosphorylation.

Strong polarization toward Th1 immune response in ANCA-associated glomerulonephritis

AIM

Human immune response can be classified into 2 different subsets of T helper cells (Th1 and Th2) based on the pattern of cytokine production. In modern immunology, Th1/Th2 paradigm helps to explain the different inflammatory effector pathways and outcomes in human diseases. The present study was designed to determine the type of immunological response that influences anti-neutrophil cytoplasmic antibody-(ANCA) associated glomerulonephritis (GN) using cytokine analysis of peripheral T cells and diseased kidney tissues.

PATIENTS AND METHODS

We analyzed peripheral blood Th1/Th2 ratio in 91 patients with primary GN, including 10 cases of ANCA-associated GN. Tissues were immunostained with markers of T cells and macrophages and osteopontin (OPN). Intrarenal expression of IFN-gamma and IL-4 mRNAs was evaluated by reverse transcriptase (RT)-PCR.

RESULTS

Peripheral Th1/Th2 ratio was significantly higher in ANCA-associated GN (19.4 +/- 9.4, mean +/- SD, n = 10), than those in healthy controls (7.6 +/- 4.1, n = 27), IgA nephropathy (9.6 +/- 5.6, n = 45), membranous nephropathy (7.1 +/- 4.4, n = 13), minimal-change nephrotic syndrome (8.2 +/- 4.5, n = 13) and focal segmental glomerulosclerosis (8.3 +/- 3.9, n = 10) (p < 0.01, each). In 7 of 10 cases of ANCA-associated GN, Th1/Th2 ratio decreased significantly after treatment with corticosteroid from 21.0 +/- 12.0 to 9.0 +/- 6.6 (p < 0.05). Immunohistochemical staining showed numerous infiltrating T cells, macrophages and OPN-positive cells in both glomerular tuft and cellular crescent; OPN-positive cell distribution was similar to that of macrophages. Intrarenal expression of IFN-gamma mRNA was strongly enhanced whereas a weak expression of IL-4 mRNA was observed especially in advanced cases showing tubulointerstitial injury.

CONCLUSION

Both peripheral and renal immune responses are strongly polarized toward Th1 type immune response in ANCA-associated GN. Peripheral Th1/Th2 ratio may reflect the immune responses in renal injury of ANCA-associated GN.

[Analysis of 942 episodes of bacteremia in a cardiology institution. Experience with the Bact-Alert system]

In Instituto de Cardiología y Cirugía Cardiovascular, Fundación Favaloro, between January 1996 and October 1999, 10,793 blood cultures and 942 episodes of bacteremia, corresponding to 1883 positive blood cultures, were studied by means of the Bact-Alert System (Organon Teknika), 94% being monomicrobial episodes. Gram positive bacteria were isolated in 45%, Gram negative in 52% and fungi in 3% of episodes. Associated foci of infection were: catheters 36.5%, mediastinitis 9%, pneumonia 6%, endocarditis 6%, abdominal 6%, urinary tract infections 9%, prosthesis 2.6%, empyema 0.2%, arthritis 0.1%, skin and soft tissue 2.5%, diarrhea 0.1%, aortic aneurysm 0.2%, meningitis 0.2%, pericarditis 0.3%, endarteritis 0.1%, infusion fluids 0.2% and unknown 21%. Median time (in hours) for positivization of blood cultures according to different foci were: catheters 16.4, mediastinitis 19.2, pneumonia 14.2, endocarditis 14.5, abdominal infections 11.8, urinary tract infections 13.0 and unknown origin 19.0. As for contaminating microorganisms, the value was 30.5. Seventy two percent of blood cultures became positive within 24 h, and 87% within 48 h; only 1% became positive between 5th and 7th day. There were no important differences in time to detect positive cultures according to different foci. It was not useful to incubate blood cultures more than five days, except for special circumstances, because it does not improve recovery of clinically significant microorganisms.

Diffuse proliferative glomerulonephritis after bone marrow transplantation

A 15-year-old boy developed nephrotic syndrome and acute renal failure 4 years after allogenic bone marrow transplantation (BMT) for lymphoid crisis of chronic myelocytic leukemia. On admission, he presented with clinical features of chronic GVHD including transient exacerbation of cholestatic liver injury. Renal biopsy showed diffuse proliferative glomerulonephritis with cellular crescents. The patient was treated with methylprednisolone pulse therapy (1 g/day, for 3 days) followed by oral prednisolone. Renal function gradually improved but nephrotic state was persistent. A second renal biopsy showed improvement of acute tubular necrosis and endocapillary proliferation and transformation of crescents into a fibrous form. After tapering of oral prednisolone, cyclophosphamide was started, which resulted in a gradual improvement of proteinuria. Several cases of nephrotic syndrome occurring after BMT have already been reported, but most cases had membranous nephropathy. In our case, renal biopsy revealed diffuse proliferative glomerulonephritis with findings of active cellular immunity, and aggressive treatment resulted in attenuation of these findings. Moreover, chronic GVHD-related liver injury was noted at the time of this episode. Our findings suggest that chronic GVHD may be complicated with diffuse proliferative glomerulonephritis through unknown cellular immune mechanism.

[Quantitative cultures from catheters, using the Brun Buisson technique]

The objective of this collaborative work carried out in the Fundación Favaloro and the Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia, was to determine optimal conditions for incubation (time and atmosphere) of quantitative cultures of catheters processed according to the technique of vortex agitation (Brun Buisson method). From 689 processed catheters, 551 yielded negative cultures. From the 138 positive cultures, 125 yielded monomicrobial cultures and 13 polimicrobial cultures (total number of microorganisms was 151). In the last situation each micoorganism was considered on an individual basis. A total of 58 episodes of catheter related bacteremias occurred, being 52 monomicrobial and 6 polimicrobial (total number of microorganisms was 64). When colony counts were compared in aerobic and in 5-10% CO2 atmospheres, a very good correlation was obtained (p = 0.27; r2 = 0.9268). No advantage was observed by incubating plates for more than 48 hours. Colony counts performed at the second versus the third day, and at the second day versus the seventh, gave very good correlation (p = 0.10 and r2 = 0.9996; p = 0.31 and r2 = 0.9995, respectively).

A male and hermaphrodite specific RAPD marker for papaya ( Carica papayaL.)

The random amplified polymorphic DNA (RAPD) technique was used to determine the sex of a dioecious species, Carica papayaL., with three sex types, male, female and hermaphrodite. A 450 bp marker fragment, named PSDM(Papaya Sex Determination Marker), exists in all male and hermaphrodite plants but not in the female plants so far analyzed. The DNA sequence of PSDM exhibited no significant similarity to previously reported sequences. A sequence-characterized amplified region (SCAR) marker, SCARps, was developed from PSDM to determine the sex of papaya. Southern hybridization, using PSDM as a probe, showed that PSDM exists in the male and hermaphrodite genomes, but not in the female genome. This result strongly suggests that PSDM is located on the chromosome region that is specific to the male and the hermaphrodite. SCARps is a suitable marker for the precise and rapid diagnosis of sex in papaya.

A major substrate for MPF: cDNA cloning and expression of polypeptide chain elongation factor 1 gamma from goldfish (Carassius auratus)

One of the eukaryotic polypeptide chain elongation factors, EF-1 beta gamma delta complex, is involved in polypeptide chain elongation via the GDP/GTP exchange activity of EF-1 alpha. In the complex, EF-1 gamma has been reported to be a major substrate for maturation promoting factor (MPF). Here, we present the cloning, sequencing and expression analysis of goldfish, Carassius auratus, EF-1 gamma from the goldfish ovary. The cloned cDNA was 1490 bp in length and encoded 442 amino acids. The deduced amino acid sequence was highly homologous to EF-1 gamma from other species. Although, the phosphorylation site identified in Xenopus EF-1 gamma was not conserved in the goldfish homologue, phosphorylation analysis showed that the goldfish EF-1 gamma was phosphorylated by MPF. We concluded that EF-1 gamma is a substrate for MPF during oocyte maturation in goldfish.

Molecular cloning of cDNA encoding polypeptide chain elongation factor 1alpha from goldfish (Carassius auratus)

The goldfish homologue of polypeptide chain elongation factor-1alpha (EF-1alpha) isolated from the ovary of the goldfish is described. The deduced amino acid sequence is highly homologous to EF-1alpha from other species. Analysis of its tissue distribution revealed a single 1.7 kilobase message ubiquitous among various tissues.

Critical exponents at the ferromagnetic transition in tetrakis(dimethylamino)ethylene-C(60) (TDAE- C(60))

Critical exponents at the ferromagnetic transition were measured for the first time in an organic ferromagnetic material tetrakis(dimethylamino)ethylene fullerene[60] (TDAE- C(60)). From a complete magnetization-temperature-field data set near T(c) = 16.1+/-0.05, we determine the susceptibility and magnetization critical exponents gamma = 1.22+/-0.02 and beta = 0.75+/-0.03, respectively, and the field vs magnetization exponent at T(c) of delta = 2.28+/-0.14. Hyperscaling is found to be violated by Omega identical with d(')-d approximately -1/4, suggesting that the onset of ferromagnetism can be related to percolation of a particular contact configuration of C(60) molecular orientations.

Quantification of TGF-beta1 mRNA along rat nephron in obstructive nephropathy

Unilateral ureteral obstruction (UUO) leads to interstitial fibrosis of the obstructed kidney, and transforming growth factor-beta1 (TGF-beta1) is thought to play an important role in this process. Although increased TGF-beta1 mRNA expression in the obstructed kidney has been demonstrated, the source of the increased TGF-beta1 remains to be elucidated. To determine the precise localization of TGF-beta1 in the obstructed kidney, we examined TGF-beta1 mRNA expression using in situ hybridization and competitive RT-PCR in rats with UUO. In situ hybridization demonstrated that TGF-beta1 mRNA expression was preferentially increased in tubular epithelial cells and to a lesser degree in infiltrating macrophages in obstructed kidneys. Quantitative analysis using competitive RT-PCR in microdissected nephron segments revealed that levels of TGF-beta1 mRNA in obstructed kidneys relative to control kidneys increased significantly in proximal tubules, thick ascending limbs of Henle, and distal convoluted tubules, whereas those in glomeruli and collecting ducts did not change significantly. Of the tubular segments, the proximal tubules appeared to predominantly contribute to increased TGF-beta1 mRNA. Our findings suggest that renal tubules, particularly proximal tubules, are the main contributors to increased TGF-beta1 mRNA expression in obstructed kidneys and to the subsequent interstitial fibrosis.

Predominance of Th1 immune response in diffuse proliferative lupus nephritis

OBJECTIVE

Lupus nephritis, which shows various histologic patterns, is a serious complication of systemic lupus erythematosus (SLE). We previously demonstrated the importance of Thl cell-mediated immune response in patients with diffuse proliferative lupus nephritis (DPLN). The aim of this study was to examine the relationship between the peripheral blood Th1/Th2 balance and the intrarenal immune response.

METHODS

The Th1:Th2 ratio in peripheral blood was measured by intracellular staining for cytokines with flow cytometry. Immunohistochemical analysis of renal biopsy specimens was performed to clarify the characterization of local infiltrating cells in 3 groups of subjects: SLE patients with World Health Organization (WHO) class IV nephritis (DPLN) (group I; n = 13), SLE patients with WHO class V nephritis (group II; n = 9), and patients with minor glomerular lesions (group III; n = 7). In addition, the histologic activity index and chronicity index were evaluated and correlated with the Th1:Th2 ratio.

RESULTS

Immunohistochemical studies showed higher numbers of CD68+ macrophages, CD3 + T cells, and interferon-gamma-positive cells in group I than in groups II or III. Renal tissues from patients in group I also showed up-regulation of expression of osteopontin and CD40, with a small number of infiltrating T cells expressing interleukin-4. Overall, the Thl:Th2 ratio in group I patients (SLE with DPLN) was high and correlated significantly with the histologic activity index, but not with the chronicity index.

CONCLUSION

We have identified a predominance of Thl-type response in both peripheral and renal tissues of patients with DPLN, suggesting that the peripheral blood Thl:Th2 ratio directly reflects the local histopathologic findings. In patients with lupus nephritis, the peripheral blood Th1:Th2 ratio could be useful as a parameter that reflects the renal histologic activity or the strength of the local Thl response.

Superconductivity in an organic insulator at very high magnetic fields

We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor lambda-(BETS)2FeCl4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe3+ ions. We further argue that the Fe3+ moments are essential to stabilize the resulting singlet, two-dimensional superconducting state.

[Utility of prolonged incubation and terminal subcultures of blood cultures from immunocompromised patients]

The value of blind terminal subcultures (7 and 30 days) and prolonged incubation (30 days) of blood cultures from immunosuppressed patients was analyzed in the Fundación Favaloro, the Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia and the Hospital de Niños Ricardo Gutiérrez. A total of 2707 blood cultures and 369 patients were included (transplantation of solid organs 154, oncohematologic disorders 106 and solid tumors 109). Bact-Alert bottles were incubated at 35 degrees C for 30 days in the Bact-Alert System. Bottles with positive signals were routinely removed, and aliquots of the broth were Gram stained and subcultured aerobically in chocolate agar and Sabouraud agar. A total of 136 bacteremic episodes were obtained. The positivization time of blood cultures was 81.6% at 24 h, 93.3% at 48 h, 94.5% at 72 h and 97.7% within 7 days. Only 3 (2.2%) episodes were positive by blind terminal subcultures and 1 (0.75%) by prolonged incubation (14 days). The median time and range of positivization in hours were 13.8 and 2.2-168, respectively. The microorganisms isolated were coagulase negative staphylococci (n = 24), Klebsiella pneumoniae (n = 22), Staphylococcus aureus (n = 21), Escherichia coli (n = 18), Acinetobacter spp (n = 9), Candida spp (n = 8), Pseudomonas aeruginosa (n = 6), Enterobacter cloacae (n = 5), Stenotrophomonas maltophilia (n = 5), Enterococcus faecalis, Salmonella spp and Capnocytophaga sputigena (n = 2), Enterobacter aerogenes, Enterococcus faecium, Citrobacter diversus, Candida albicans, Klebsiella oxytoca, Chryseomonas luteola, Serratia marcescens, Abiotrophia spp, Campylobacter jejuni, Moraxella catarrhalis, Moraxella urethralis, Neisseria sicca, beta hemolytic group G streptococci, Rhodococcus equi, Micrococcus spp, Cryptococcus neoformans and Streptococcus mitis (n = 1). In our experience, blind terminal subcultures and prolonged incubation of blood cultures from immunosuppressed patients are unnecessary and cost expensive.

Molecular cloning of ubiquitin-activating enzyme (E1) from Xenopus laevis

The Xenopus homologue to the ubiquitin-activating enzyme (E1) from a Xenopus ovary is described. The deduced amino acid sequence is highly homologous to E1 from other species.

Magnetic-field-induced superconductivity in a two-dimensional organic conductor

The application of a sufficiently strong magnetic field to a superconductor will, in general, destroy the superconducting state. Two mechanisms are responsible for this. The first is the Zeeman effect, which breaks apart the paired electrons if they are in a spin-singlet (but not a spin-triplet) state. The second is the so-called 'orbital' effect, whereby the vortices penetrate into the superconductors and the energy gain due to the formation of the paired electrons is lost. For the case of layered, two-dimensional superconductors, such as the high-Tc copper oxides, the orbital effect is reduced when the applied magnetic field is parallel to the conducting layers. Here we report resistance and magnetic-torque experiments on single crystals of the quasi-two-dimensional organic conductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. We find that for magnetic fields applied exactly parallel to the conducting layers of the crystals, superconductivity is induced for fields above 17 T at a temperature of 0.1 K. The resulting phase diagram indicates that the transition temperature increases with magnetic field, that is, the superconducting state is further stabilized with magnetic field.

Field-induced dynamic diamagnetism in a charge-density-wave system

ac susceptibility measurements of the charge-density-wave (CDW) compound alpha-(BEDT-TTF)(2)-KHg(SCN)(4) at magnetic fields, mu0H >23 T, above its Pauli paramagnetic limit, reveal unambiguously that the magnetic hysteresis observed previously within this CDW phase is diamagnetic and can only be explained by induced currents. It is argued that the ensemble of experimental techniques amounts to a strong case for dissipationless conductivity within this phase.

A novel antiferromagnetic organic superconductor kappa-(BETS)(2)FeBr(4) [where BETS = bis(ethylenedithio)tetraselenafulvalene]

The electrical and magnetic properties of kappa-(BETS)(2)FeBr(4) salt [where BETS = bis(ethylenedithio)tetraselenafulvalene] showed that this system is the first antiferromagnetic organic metal at ambient pressure (T(N) = 2.5 K). The characteristic field dependence of the magnetization at 2.0 K indicates a clear metamagnetic behavior. The small resistivity drop observed at T(N) clearly shows the existence of the interaction between pi metal electrons and localized magnetic moments of Fe(3+) ions. In addition, this system underwent a superconducting transition at 1.1 K. That is, kappa-(BETS)(2)FeBr(4) is the first antiferromagnetic organic metal exhibiting a superconducting transition below Néel temperature. The magnetic field dependence of the superconducting critical temperature indicated that the superconductivity in this system is strongly anisotropic also in the conduction plane because of the existence of the metamagnetically induced internal field based on the antiferromagnetic ordering of the Fe(3+) 3d spins in contrast to the cases of the other conventional organic superconductors. Furthermore, the specific heat measurement exhibited a lambda-type large peak of zero-field specific heat corresponding to the three-dimensional antiferromagnetic ordering of high-spin Fe(3+) ions. The lack of distinct anomaly in the C(p) vs T curve at T(c) suggests the coexistence of the superconductivity and the antiferromagnetic order below T(c).

[Experimental model of infection of Helicobacter pylori in the mouse. A study of gastric damage caused by indomethacin]

INTRODUCTION

The action of non-steroidal anti-inflammatory drugs (NSAIDs) on the Helicobacter Pylori (Hp) infected mucosa is a matter of debate. Some authors consider them to cause additive iatrogeny whilst others attribute a purportedly protective action to them. The development of on experimental animal model could help clarify this phenomenon.

OBJECTIVES

1--To develop an animal model of Hp gastric infection. 2--To evaluate the aggressiveness of NSAIDs in this model.

MATERIALS AND METHODS

Male 6 month old BALC/C mice weighing 38 g were studied. Pylori Hp infection was ruled out. On three occasions, in the same week, 18 mice were inoculated intra-gastrically with 0.6 ml of Hp culture broth (brain-heart infusion) containing 1 x 10 8-1 x 10 9 CFU/ml. Another group of mice were inoculated with sterile saline. After two months the mice were killed and their stomachs studied. They were divided into groups: a) 6 Hp negative control mice. b) 8 Hp negative mice with prior intra-peritoneal injection of 25 mg/Kg indomethacin (24 hs.) c) 8 mice inoculated with Hp with indomethacin. d) 8 mice inoculated with Hp, without indomethacin. The stomachs were opened along the greater curvature and photographed macroscopically in order to map the necrotic area. The antrums were biopsied to test for urease and separate antrum and body specimens were send for staining with Warthin-Starry H & B and histopathology.

RESULTS

All the mice inoculated with Hp acquired the infection. The necrotic area was larger in Group B: 55.5 +/- 7.87 mm than in Group C: 15 +/- 1.82 mm P < 0.00019.

HISTOLOGY

Group A: normal mucosa. Group B: extensive coagulation necrosis and focal erosions. Group C: ulcers with inflammatory infiltrate and smaller necrotic area, presence of Hp on the surface epithelium. Group D: no ulcers, Hp present.

CONCLUSION

An animal model of Hp infection was successfully developed Hp infection could play a potentially protective role against indomethacin aggression in the mouse.

Reconstitution of sperm nuclei of zebrafish (Danio rerio) in Xenopus egg extracts

Cell-free extracts of Xenopus eggs cause cyclic change in permeabilized sperm nucleus, nuclear envelope breakdown, chromosome condensation, and reformation of nuclei. In this study, the ability of cell-free extracts to cause similar changes in zebrafish sperm was examined. When lysolecithin-treated sperm from zebrafish were incubated in Xenopus egg extracts, a series of changes in sperm nuclear morphology were observed periodically. These changes correlated with maturation-promoting factor (MPF) activity. Furthermore, sperm nuclei of zebrafish replicated DNA during reconstitution in Xenopus egg extracts. These results showed that cell-free extracts of Xenopus egg possess the ability to cause cell-cycle-dependent changes in zebrafish sperm, implying the possibility of generating transgenic zebrafish in a similar way to transgenic Xenopus.

Origin of ferromagnetic exchange interactions in a fullerene-organic compound

Organic ferromagnets, which exhibit exchange interactions between unpaired electrons in pi-orbitals, are rare, and the origin of ferromagnetism in these compounds has so far remained unexplained. Tetrakis(dimethylamino)ethylene-fullerene[60] (TDAE-C60) shows a transition to a ferromagnetic state with fully saturated s = 1/2 molecular spins at the relatively high Curie temperature (for organic materials) of 16 K (ref. 4). It has been suggested that the orientations of the C60 molecules may be important for ferromagnetism in this material, but in the absence of structural data at low temperatures there has been little progress towards understanding these microscopic interactions. Here we report the results of a comparative structural study of two different magnetic forms of TDAE-C60 crystals at low temperatures, correlating the structural properties--in particular, the intermolecular orientations--with the magnetic properties. We find that both ferromagnetism and spin-glass-like ordering are possible in this material, and depend on the orientational state of C60 molecules. This resolves the apparent contradictions posed by different macroscopic measurements, and opens the way to a microscopic understanding of pi-electron ferromagnetic exchange interactions in organic materials.