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  • 1
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We monitored the compositional change of host RNA polymerase in Xp 10 infected cells by one-step immunoprecipitation with core enzymespecific antiserum. Results showed a rapid loss of σ subunit from the RNA polymerase complex by 3 min after infection. In addition, some putative binding proteins were reduced to various extents. In contrast, increasing levels of several other polypeptides were detected. The de novo host protein synthesis was inhibited within 1 min after Xp 10 infection. On the other hand, a sequential expression of phage specific proteins was found and can be categorized as early, middle, and late stage. The alteration of host RNA polymerase and the shutdown of early class proteins took place in parallel.
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  • 2
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In this study the lytic cycle of a filamentous phage is reported. Under normal laboratory cultivation conditions a virulent form could spontaneously and easily arise from a temperate phage. The virulent one could superinfect cells containing Cf1t lysogen. Therefore, we have named it Cf1tv. In a colony formation assay using cells from an infected culture, two types of colonies were observed, small and large. It could be proven that the formation of small colonies is the result of killing during Cf1tv infection. The number of small colony forming units (cfu) increased with infection time and reached a maximum at 16 h after infection, then dropped to the initial cell concentration at 28 h after infection; 28 h were required to kill all infected cells. Large colonies contained uninfected or phage-resistant cells, but no lysogenic cells. Bacterial death was further confirmed by a microculture assay. At 2 h after infection, normal-dividing cells (cfu giving large colonies) contained about 40% of Cf1tv-infected cells, then the percentage decreased with infection time. Slow-dividing cells (infected cfu giving small colonies) initially contained 55% of cells; this percentage increased slightly at 4 h after infection, then decreased at 8 h after infection. Non-dividing cells initially contained 5% of infected cells, then their numbers rapidly increased with time after infection. The cell division was seriously affected and finally stopped. During one-step growth, the latent period was 30 min and there was no burst; phages were released at 30 min after infection and the rate of release increased gradually with time after infection. Phage DNA integration into host chromosome could not be observed.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A variant of Saccharomyces cerevisiae pep4 strain 20B12, with improved oligotrophic proliferation, cell survival and secretion of heterologous mouse α-amylase, is described. Previously we reported a procedure to enrich NI transformants that are not inhibited by cytotoxic expression of hepatitis B virus surface antigen in the secretion pathway of the protease-A-deficient (pep4) strain. To use the NI cells as a host for heterologous expression, we tried to amend the introduced pYAS/12S vector and obtain a host strain, NI-C, with stable NI phenotype and trp1 marker restored. Southern analysis of genomic DNA of NI-C suggested that the original pYAS/12S was abnormally rearranged and not completely corrected. Further assay showed that the viability and mitotic ability of the NI-C strain were increased. While using the NI-C strain as host for plasmid transformation and heterologous expression of mouse α-amylase, we observed that transformed colonies grew more quickly and secreted more α-amylase than general yeast strains. A further test showed that the NI-C strain was able to use mouse α-amylase as a positive selection marker to form transformed colonies on nitrogen-starved plates that contain starch as the sole carbon source. The results imply that the NI-C variant is an improved pep4 strain that can be used for heterologous expression and for the development of new selective markers in the yeast transformation system.
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  • 4
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The consequences of the variational definition of the self-consistent potential in Brueckner-Hartree-Fock theory are explored to higher orders even summing up some classes of diagrams to infinity. The consistency of this definition with a diagrammatic expansion are checked. Overcounting terms in the variational approach are pointed out and their numerical influence on the ground state properties of nuclei is checked at the example of16O. Ambiguities of the potential defined by the variational procedure stemming from the property of the Pauli-operatorQ 2 =Q are studied diagrammatically and numerically. The application to16O shows that the influence of the Pauli rearrangement term is partially cancelled by the higher order starting energy rearrangement terms discussed in this work.
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  • 5
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ten nitrate reductase-deficient Hordeum vulgare mutants were characterized for NADH and FMNH2 nitrate reductase (NR), cytochrome C reductase (CR) and nitrite reductase (NiR) activities. The mutants sort into four major groups. Group I represented by mutants Az 12, Az 23, Az 29 and Az 30 have low Nr and Cr activities. Group II represented by mutants Az 13, Az 31, Az 33 and Az 34 have low NR activities but intermediate CR activities. Group III represented by mutant Az 28 has low NR activity, but above normal CR activity. Group IV represented by Az 32 has low NADH-NR, low CR, but above normal FMNH2-NR activity. All ten mutants have elevated NiR activities. None of the ten mutants were constitutive for nitrite reductase activity. Only Az 34 showed a definite high temperature sensitivity when the NADH nitrate reductase activity was compared in the 12 to 26° C range. The mutants Az 12, Az 13, Az 23, Az 28, Az 29, Az 30, Az 31, Az 32 and Az 33 are allelic and were assigned the locus designation nar1. Mutant Az 34 represents a different genetic locus designated nar2. The nar1 gene is codominant and the nar2 gene is recessive.
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  • 6
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ten nitrate reductase (NR)-deficient mutants have been characterized for their cross-reactivity against specific barley (Hordeum vulgare L.) nitrate reductase antibodies. The rabbit antibodies raised against the purified barley wild type (cv. Steptoe) enzyme quantitatively inactivate nitrate reductase in crude extracts. All nitrate-grown (induced) mutants show positive precipitin reaction against the antiserum by Ouchterlony double diffusion test and all have the ability to neutralize antisera in a NR protection assay. Under induced growth conditions, mutants Az 12, Az 23, Az 29 and Az 30 which have low NR associated catalytic activities also have the lowest level of antigenicity; mutants Az 13, Az 31, Az 33 and Az 34 have intermediate level of both NR associated catalytic activities and antigenicity, while mutants Az 28 and Az 32 have the highest level of both NR associated catalytic activities and antigenicity. Under noninduced growth conditions, all mutants except Az 12 contain detectable but very low levels of NR antigenicity. These results support the concept that these NR-deficient mutants with various levels of NR associated catalytic activities represent different mutation events at the loci coding the NR structural components.
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  • 7
    ISSN: 1617-4623
    Keywords: Key wordsXanthomonas campestris pv. citri ; Bacterio- phage cf ; Pilin ; pilA ; Infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Host factors that are important for infection of Xanthomonas campestris pv. citri by the filamentous bacteriophage cf were investigated by transposon mutagenesis with Tn5tac1. A mutant, XT501, that was resistant to cf infection was recovered, showing that the gene inactivated by the transposon is required for infection by the phage but not for cf replication or assembly. A 1.7-kb SacI-ApaI DNA fragment from XT501 containing the bacterial DNA flanking one end of the transposon was cloned and shown to be required for cf infection. Nucleotide sequence analysis of the 1.7-kb fragment reveals the presence of an ORF that encodes a protein of 146 amino acids. This protein shows 42% identity to the type 4 prepilin encoded by the pilA genes of other bacteria. The pilA gene of X. campestris pv. citri is thus essential for infection by the bacteriophage cf.
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  • 8
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We calculate the ground-state energy of normal and spin-polarized3He within a model-space ring diagram framework where the particle-particle hole-hole (pphh) ring diagrams of the ground-state energy shift are summed up to all orders. The Aziz HFDHE2 and HFD-B(HE) interactions are employed. We first calculate a model space reaction matrix(G M ) whose intermediate states are required to be outside the chosen model space. The pphh ring diagrams withG M -matrix vertices are then summed within the model space by way of a PRA-type secular equation. The continuous single-particle spectrum of Mahaux is chosen in the present work. It is found that the inclusion of the pphh ring diagrams gives a significant increase in the binding energy per particle(BE/A) as compared with Brueckner-Hartree-Fock calculations. For normal and spin-polarized3He our calculated values forBE/A and saturation densities are respectively (1.86 K, 0.72 Å−1) and (1.59 K, 0.91 Å−1), while the corresponding experimental values for normal3He are (2.47 K, 0.785 Å−1).
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  • 9
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ein 24jähriger Mann klagte seit drei Monaten über unklares abdominelles Völlegefühl und einen dumpfen, leicht epigastrischen Schmerz. Zwei Monate vor Aufnahme war in einem klinischen Zentrum ein Pankreaskopftumor festgestellt worden. Sonographisch, durch endoskopische retrograde Cholangiopankreatographie und Computertomographie des Abdomens wurde der Pankreaskopftumor bestätigt. Wegen des hochgradigen Verdachtes auf Pankreaskopfkarzinom wurde eine Laparotomie vorgenommen. Dabei fand sich im Pankreaskopf eine indurierte Masse, vergrößerte Lymphknoten und weiße Tuberkel auf dem Darm. Die histologische Untersuchung bestätigte das Vorliegen tuberkulöser Granulome. Säurefeste Stäbchen konnten histologisch ebenfalls nachgewiesen werden. Der Patient wurde mit Tuberkulostatika behandelt und ist jetzt in guter Verfassung. Um unnötige Laparotomien zu vermeiden, sollte bei Patienten mit Pankreastumor eine computertomographisch oder sonographisch kontrollierte Aspirationsbiopsie mit zytologischer oder histologischer Untersuchung durchgeführt und auch kulturell der Nachweis von Mykobakterien versucht werden. Dies gilt vor allem für Regionen, in denen die Lungentuberkulose und abdominelle Tuberkulosen keine Seltenheit darstellen.
    Notes: Summary A 24-year-old man presented with vague abdominal fullness and a mild epigastric dull pain for about 3 months was found to have a pancreatic head tumor at a medical center 2 months ago. He came to our hospital for further treatment. Ultrasonography, endoscopic retrograde cholangiopancreatography (ERCP) and abdominal computed tomography (CT) all revealede a pancreatic head tumor. Laparotomy was performed because pancreatic head carcinoma was highly suspected. Indurated mass in the pancreatic head, enlarged lymph nodes and white tubercles on the intestine proved to be tuberculosis on histological examination of a frozen section. Acid fast bacilli were also found. The patient was given antituberculous therapy and is now doing well. To avoid unnecessary laparotomy, CT, echo-guided percutaneous aspiration cytology or biopsy and culture of the tissue for mycobacteria should be done in a patient with pancreatic mass, especially in a region where pulmonary and abdominal tuberculosis are common.
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  • 10
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Fusarium wird im allgemeinen als opportunistischer Pilz beim Menschen angesehen. Im Fuß einer Patientin ohne Abwehrschwäche trat eine abszedierende Infektion durchFusarium solani auf, die sogar nach intravenöser Amphotericin B-Therapie rezidivierte.
    Notes: Summary Fusarium spp. are usually considered opportunistic fungi in humans. A case ofFusarium solani abscess formation of the foot in an immunocompetent patient in whom recurrence occurred even after intravenous amphotericin B treatment is presented here.
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