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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric radiology 10 (1981), S. 201-205 
    ISSN: 1432-1998
    Keywords: Pyloric stenosis ; Pylorospasm ; Gastric outlet obstruction ; Infant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Short segment narrowing of the pyloric canal is a common finding in infants with chronic vomiting, and most often is due to pylorospasm. In such cases, it is transient, and offers no real problem in diagnosis. On the other hand, when it persists, a question arises as to whether it is due to fixed stenosis. Differentiation of the two conditions is difficult, but important, for while spasm can be treated medically, true stenosis requires surgical intervention. Just how to accomplish this differentiation is the subject of this report, and for the most part, centers around the infant's response to a therapeutic trial of antispasmodics. Patients with pylorospasm respond favorably, while those with fixed stenosis do not. Generally, these latter patients require polyromyotomy, but in the occasional infant, so little muscle hypertrophy is present that we have found pyloroplasty to be the preferred procedure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 168 (1997), S. 240-244 
    ISSN: 1432-072X
    Keywords: Key words Catabolite regulation ; Cra protein ; Nitrite ; reductase regulation ; Escherichia coli ; Catabolite ; repression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Escherichia coli nir and nrf operons, which encode alternative nitrite reductases expressed during anaerobic growth, are subject to catabolite regulation. Transcription from the nir promoter is maximal when bacteria are grown in rich media such as Lennox broth supplemented with glucose. Conversely, expression of the nrf operon is suppressed by rich media, but stimulated during growth in minimal medium with glycerol and fumarate. The role of the catabolite repressor-activator (Cra) protein in catabolite regulation of the nir and nrf promoters was investigated. Transcription from the nir promoter was repressed by Cra when cells were grown in minimal medium with glycerol and fumarate. Crude protein extracts from a strain overproducing Cra encoded on a multicopy plasmid retarded a nir promoter fragment in a mobility shift assay, confirming that the observed Cra-dependent repression was due to the direct interaction of Cra with the regulatory region of the nir operon. Furthermore, the inclusion of fructose 1-phosphate, an effector of Cra DNA-binding activity, in the assay decreased the ability of Cra to retard the nir promoter fragment. In contrast, transcription from the nrf promoter was not regulated by Cra under any of the growth conditions tested.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1617-4623
    Keywords: Key words Disulphide bond formation ; Cytochrome c assembly ; Nitrite reduction ; Nitrate reduction ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The assembly of anaerobically induced electron transfer chains in Escherichia coli strains defective in periplasmic disulphide bond formation was investigated. Strains deficient in DsbA, DsbB or DipZ (DsbD) were unable to catalyse formate-dependent nitrite reduction (Nrf activity) or synthesize any of the known c-type cytochromes. The Nrf+ activity and cytochrome c content of mutants defective in DsbC, DsbE or DsbF were similar to those of the parental, wild-type strain. Neither DsbC expressed from a multicopy plasmid nor a second mutation in dipZ (dsbD) was able to compensate for a dsbA mutation by restoring nitrite reductase activity and cytochrome c synthesis. In contrast, only the dsbB and dipZ (dsbD) strains were defective in periplasmic nitrate reductase activity, suggesting that DsbB might fulfil an additional role in anaerobic electron transport. Mutants defective in dipZ (dsbD) were only slightly more sensitive to Cu++ ions at concentrations above 5 mM than the parental strain, but strains defective in DsbA, DsbB, DsbC, DsbE or DsbF were unaffected. These results are consistent with our earlier proposals that DsbA, DsbB and DipZ (DsbD) are part of the same pathway for ensuring that haem groups are attached to the correct pairs of cysteine residues of apocytochromes c in the E. coli periplasm. However, neither DsbE nor DsbF are essential for the reduction of DipZ (DsbD).
    Type of Medium: Electronic Resource
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