Fission yeast pap1-dependent transcription is negatively regulated by an essential nuclear protein, crm1.

The fission yeast pap1+ gene encodes an AP-1-like transcription factor that contains a leucine zipper motif. We identified a target gene of pap1, the p25 gene. The 5' upstream region of the p25 gene contains an AP-1 site, and by DNase I footprint analysis, we showed that the pap1 protein binds to the AP-1 site as well as to a 14-bp palindrome sequence. p25 is overproduced when the pap1+ gene is overexpressed, whereas p25 is not produced at all in the pap1 deletion mutant. p25 was previously found to be overproduced in strains carrying cold-sensitive crm1 mutations whose gene product is essential for viability and is thought to play an important role in maintenance of a proper chromosomal architecture. Deletion and site-directed mutagenesis of sequences upstream of the p25 gene demonstrated that the AP-1 site as well as the palindrome sequence are crucial for transcriptional activation either by pap1 overproduction or by the cold-sensitive crm1 mutation; pap1+ is apparently negatively regulated by crm1+. Moreover, we found that cold-sensitive crm1 mutations are suppressed by the deletion of pap1+, further indicating a close relationship between crm1+ and pap1+. The crm1 protein is highly conserved; the budding yeast homolog, CRM1, which complements the fission yeast cold-sensitive crm1 mutation, was isolated and found to also be essential for viability. These results suggest the functional importance of chromosome structure on the regulation of gene expression through the pap1 transcription factor.

A screen for targets of the Xenopus T-box gene Xbra.

Brachyury (T), a member of the T-box gene family, is essential for the formation of posterior mesoderm and notochord in vertebrate development. Expression of the Xenopus homologue of Brachyury, Xbra, causes ectopic ventral and lateral mesoderm formation in animal cap explants and co-expression of Xbra with Pintallavis, a forkhead/HNF3beta-related transcription factor, induces notochord. Although eFGF and the Bix genes are thought to be direct targets of Xbra, no other target genes have been identified. Here, we describe the use of hormone-inducible versions of Xbra and Pintallavis to construct cDNA libraries enriched for targets of these transcription factors. Five putative targets were isolated: Xwnt11, the homeobox gene Bix1, the zinc-finger transcription factor Xegr-1, a putative homologue of the antiproliferative gene BTG1 called Xbtg1, and BIG3/1A11, a gene of unknown function. Expression of Xegr-1 and Xbtg1 is controlled by Pintallavis alone as well as by a combination of Xbra and Pintallavis. Overexpression of Xbtg1 perturbed gastrulation and caused defects in posterior tissues and in notochord and muscle formation, a phenotype reminiscent of that observed with a dominant-negative version of Pintallavis called Pintallavis-En(R). The Brachyury-inducible genes we have isolated shed light on the mechanism of Brachyury function during mesoderm formation. Specification of mesodermal cells is regulated by targets including Bix1-4 and eFGF, while gastrulation movements and perhaps cell division are regulated by Xwnt11 and Xbtg1.

Interaction of amphotericin B with cholesterol in monolayers, aqueous solutions, and phospholipid bilayers.

The interaction of amphotericin B (AmB) with cholesterol was investigated in monolayers, aqueous solutions, and phospholipid vesicles. When AmB was mixed with cholesterol, it formed a stable monolayer, implying complex formation in which the stoichiometry was primarily 1:1 AmB:cholesterol. However, the interaction of AmB with cholesterol in aqueous solutions and lipid vesicles was more complex. In aqueous solutions, cholesterol at low concentrations increased the aggregation of AmB. But higher concentrations of cholesterol caused dissociation of the aggregates of AmB due to the formation of AmB-cholesterol complexes. In lipid vesicles, the effect of cholesterol was different from that in aqueous solutions. Both in aqueous solutions and lipid vesicles, the overall dissociation of AmB molecules occurred on interaction with cholesterol. In addition, the interaction of lipid membranes with AmB-cholesterol complexes was investigated by differential scanning calorimetry. The incorporation of AmB into lipid bilayers led to broadening of the lipid transition and a slight decrease in the transition enthalpy, showing that one lipid molecule per AmB molecule was immobilized. However, the number of immobilized lipid molecule per AmB molecule increased in the coexistence of cholesterol, due to the complex formation between AmB and cholesterol.

[Serotype and susceptibilities to eight antibiotics of fifty strains of Pseudomonas aeruginosa isolated from clinical specimens and changes in susceptibilities of Pseudomonas aeruginosa to various antibiotics during a period between 1983 and 1986].

Efficacies of 8 antibiotics against Pseudomonas aeruginosa in the relation to serotypes and clinical sources were investigated on 50 strains isolated from patients at Nagoya Ekisaikai Hospital between August and September, 1986. Disk sensitivity test was carried out simultaneously for 5 antibiotics including piperacillin (PIPC), cefoperazone (CPZ), cefsulodin (CFS), ceftazidime (CAZ) and amikacin (AMK), using the single-disk method. We also examined changes in susceptibilities of P. aeruginosa to 5 antibiotics including PIPC, CFS, fosfomycin, gentamicin (GM) and AMK during last 4 years (1983-1986). The results are summarized as follows. 1. CAZ and AMK proved to have high antibacterial potencies, and their MIC80's (concentrations to inhibit growth of 80% of objective bacteria) were both 6.25 micrograms/ml. Following these two the order of potencies were; CFS, cefpiramide (CPM), PIPC, CPZ, netilmicin (NTL), and cefmenoxime (CMX). Sixty two percent of the strains of P. aeruginosa showed high resistances (MIC greater than 50 micrograms/ml) to CPM, CPZ, NTL and CFS, 58% to PIPC, and 2% to AMK. 2. With regard to serotypes, strains belonging to type E were less susceptible than those belonging to types G and I. Type E strains showed high resistance to all antibiotics except CAZ and AMK. 3. Strains obtained from pura and secreta were relatively susceptible, while those from urines were resistant, to these antibiotics tested, in general. 4. Good correlation between MIC's obtained with the agar dilution method (MIC less than or equal to 12.5 micrograms/ml) and these with the disk sensitivity test (greater than ¿ was observed. chi 2 statistical analysis showed that the results obtained with the 2 methods were closely related (P less than 0.01). 5. P. aeruginosa showed fairly high susceptibility to AMK through the recent 4 years (1983-1986). On the other hand, highly resistant strains against CFS, PIPC, FOM and GM increased rapidly during this period.

[In vitro combination effects of astromicin and beta-lactam antibiotics against CFS-sensitive and CFS-resistant Pseudomonas aeruginosa. In vitro synergistic activity].

We investigated in vitro synergistic activity of astromicin (ASTM) combined with beta-lactam antibiotics (cefsulodin (CFS), cefoperazone (CPZ), ceftazidime (CAZ), piperacillin (PIPC) and fosfomycin (FOM) against fresh clinical isolated Pseudomonas aeruginosa, which consisted of 13 CFS sensitive (MIC less than or equal to 3.13 micrograms/ml) and 19 CFS resistant (MIC greater than or equal to 400 micrograms/ml) strains according to the FIC index. Against CFS-sensitive P. aeruginosa, ASTM showed good synergistic activities when combined with PIPC (54%), CAZ (38%), CPZ (23%) and CFS (8%). Against CFS-resistant P. aeruginosa, ASTM also showed high synergistic activities when combined with CAZ (63%), CPZ (47%), PIPC (37%) and CFS (11%). Among the CFS-resistant P. aeruginosa, one clinical isolate showed a high sensitivity (MIC0.78 micrograms/ml) against ASTM alone.

[Cold agglutinin hemolytic anemia complicating mycoplasma pneumonia].

A case of Mycoplasma pneumonia complicated with severe hemolytic anemia, which occurred as a result of a high titer of cold agglutinin is presented. A 49 year-old male was admitted because of fever, jaundice and dyspnea. Chest x-ray showed diffuse small nodular infiltrates throughout both lung fields. Laboratory studies disclosed the following values: Hb 4.6 g/dl, Ht 13.9%, reticulocyte 11.5%, direct and indirect Coombs' test positive, haptoglobin 38 mg/dl, ESR 145 mm/hr, cold agglutinin titer 1:2,048 mycoplasma antibody titer 1:640, PPD negative. The diagnosis of autoimmune hemolytic anemia associated with Mycoplasma pneumonia was made, and treatment with minocycline and prednisolone observed striking clinical improvement. It was suggested that the cold exposure was possibly a major factor in the pathogenesis of hemolysis in this patient.

[Aggressive transformation of an indolent myeloma with abdominal extramedullary plasmacytoma after 6-year period of observation].

62-year-old female, who had been under observation for an indolent myeloma for six years without therapy, was admitted because of left flank pain. Various imaging modalities disclosed left pleural effusion, and a huge abdominal tumor involving the left crus of the diaphragm, spleen, stomach, pancreatic tail, left adrenal gland, left kidney and left posterior abdominal wall. Morphological and immunological examinations revealed extensive proliferation of more anaplastic myeloma cells within the tumor and in the pleural effusion than those in bone marrow on admission or at the beginning of the period of observation. Chemotherapy reduced serum M-protein, but LDH, the volume of the pleural effusion, and the size of the tumor increased. She died of pancreatitis associated with massive bleeding from the gastric tumor. Renal function was well preserved until her terminal phase. The clinical course showed the progression of indolent myeloma into an aggressive one without chemotherapeutic intervention, implying a rare subtype in terms of the natural history of multiple myeloma.

[Effects of volatile anesthetics on force interval relationships in guinea-pig atrial preparations].

Depressant effects of halothane, enflurane and isoflurane on isolated guinea-pig left atrial muscles bathed in Tyrode's solution at 30 degrees C were examined. Contractions were elicited by stimulation through external field electrodes while tension was recorded continuously. Frequency-force relationships at stimulation rates of 0.1, 0.2, 0.5 and 1 Hz were studied. The pD2 values of these volatile anesthetics at each stimulation rates were not different significantly, suggesting the frequency-independent depressions of these anesthetics. Interval-strength relationships at time intervals of 0.3-20 sec during 1 Hz-stimulation were also studied. Mechanical restitution curves after converting to logistic function reached a peak at 8-20 sec and were fitted well to double exponential functions with time constants of 200-600 msec (k1) and 2-6 sec (k2). All volatile anesthetics depressed the magnitude constants for fast response in a dose dependent manner. Accordingly, at high concentrations, mechanical resuscitation curves tended to fit single exponential function. Halothane and enflurane did not alter time constant k1, k2 significantly, while isoflurane increased k2 significantly. These results suggest that the mechanisms of myocardial depressant effects are different between these anesthetics.

[Complete disruption of cervical trachea, whose distal airways were migrated into the mediastinum].

The first case was a 55-year-old man, who suffered by a rope while driving his motor bicycle. On 7th day after injury, tracheotomy was scheduled due to progressive dyspnea. Following intubation of a endotracheal tube, his trachea was ruptured. The second case was a 16-year-old man, who was stabbed his trachea with a sword by his mother. His trachea completely separated following coughing during the examination of bronchoscopy. For 2 cases, we immediately excised their necks for tracheotomy but couldn't find their distal portion of trachea, because they were migrated into the mediastinum. We inserted our finger into the mediastinum for exploration and could draw it back. Both case's postoperative course was uneventful. Whenever cervical trachea is completely separated, tracheal distal end may be pulled down into the mediastinum. We invited new technique of exploration for migrated trachea using our finger.

[Studies on colonic mucus release--II. Damaged colon mucosa].

The release of goblet cell mucus (GCM) was examined in immune reaction-system of colonic mucosa of rats (SD rats). We previously reported that in the immune reaction of normal colon of rats, the discharge of colonic GCM was not increased by intrarectal instillation (challenge) of several test-antigens after repeated immunization of single BSA antigen through rectal mucosa, and there was difference in local antigen-antibody reaction on the surface of normal mucosa between small intestine and colon. In the present study we investigated the release of colonic GCM in local antigen-antibody system in rats of damaged colon mucosa, who had repeated immunization of BSA after damage induction by intracolonic infusion of formalin. Consequently, the discharge of colonic GCM increased associated with local antigen-antibody reaction in animals after damage induction by formalin. It is suggested that when the mucosal barrier is disrupted, enhanced release of colonic GCM is occurred by the local immune reaction on the surface of colonic mucosa.

The efficacy of student-centered instruction in supporting science learning.

Transforming science learning through student-centered instruction that engages students in a variety of scientific practices is central to national science-teaching reform efforts. Our study employed a large-scale, randomized-cluster experimental design to compare the effects of student-centered and teacher-centered approaches on elementary school students' understanding of space-science concepts. Data included measures of student characteristics and learning and teacher characteristics and fidelity to the instructional approach. Results reveal that learning outcomes were higher for students enrolled in classrooms engaging in scientific practices through a student-centered approach; two moderators were identified. A statistical search for potential causal mechanisms for the observed outcomes uncovered two potential mediators: students' understanding of models and evidence and the self-efficacy of teachers.