Biomedical subjects
Publications and source records attributed to W Reichardt.
Two cases of oesophageal intramural pseudodiverticulosis are described. They presented with typical numerous pseudodiverticula, each one or several millimetres in size, within the mucosa. One patient had a fibrous stenosis. In both cases CT showed localised thickening of the wall of the oesophagus. The few reports in the literature concerning histology, clinical findings and aetiology are reviewed.
The clinical and radiological features of primary adenocarcinoma of the duodenum are demonstrated by seven histologically confirmed cases. Clinically, obstruction develops following a prolonged uncharacteristic prodromal stage. The radiological findings resemble those of a carcinoma in any other part of the gastro-intestinal tract: polypoid filling defects, ulcers, mural thickening and loss of elasticity. The radiological method of choice is hypotonic duodenography. Sonography and CT are complimentary methods and are of use in postoperative follow-up.
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Diagnostic procedures of soft tissue lesions have considerably improved by the high density resolution of computed tomography. Indications for investigations by CT are described in detail and illustrated by examples. Enhancement by contrast medium enables further differentiation of the tumors. In most cases for cancer control the scar tissue can be differentiated from relapse. Comparison of both sides reveals isodense tumors. Limits of the CT method will be met in looking for discreet changes in the joints.
By using electron microscopy of self-annealed DNA and restriction enzyme analysis, we have compared the physical maps of two group A streptococcal plasmids associated with conventional MLS resistance (pEL1; 20 Md) and zonal lincomycin resistance (pSM10419; 15 Md). Of their monomeric molecules, about 40% and 60%, respectively, are occupied by identical non-tandem inverted repeats containing sequences specifying putative replication functions. Sequence homology also exists between their resistance determinants which are located in unique DNA. Moreover, homology between additional regions of unknown function is so extensive and restriction fragment arrangement so similar that, formally, pSM10419 can be considered a deletion variant of pEL1. The results suggest that MLS and zonal lincomycin resistance have the same biochemical basis (i.e. methylation of 23S ribosomal RNA) and differ only quantitatively in the inducible control systems.
Selective enrichment of yellow-orange-pigmented, gram-negative bacteria related to Cytophaga johnsonae from lake sediment was dependent on low temperatures (ca. 5 degrees C). However, this temperature effect was abolished when excessive amounts of dissolved organic carbon (10 mM N-acetylglucosamine) were added. A psychrotrophic freshwater isolate of C. johnsonae was used to study the physiological versatility of this group. Exponential growth rates were found to be dependent on the temperature to which the cells used as the inocula were acclimated. Glucose incorporation and respiration were also dependent upon the acclimation temperature of the inocula. Patterns of CO(2) evolution obtained from position-labeled [C]glucose indicated that glucose was predominantly metabolized via the Embden-Meyerhof-Parnas pathway, which, however, was greatly reduced at 25 degrees C when the concentration of glucose was as low as 5 muM/liter. Transport, respiration, and incorporation of glucose (0.2- to 20,000-muM/liter concentrations) into macromolecular cellular compounds were characterized by multiple K(m) values which were a function of substrate concentration and temperature. It appeared possible that these multiple K(m) values reflected the changing participation of the Embden-Meyerhof-Parnas pathway in glucose metabolism. These results may provide a physiological explanation for the selective enrichment of psychrotrophic freshwater cytophagas. Moreover, they exhibit the limits of interpreting kinetic data based on conventional heterotrophic potential measurements, especially when some complications may arise from temperature and substrate adaptations of the more versatile members of the chemoorganotrophic microflora such as C. johnsonae.
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The phenomenon of zonal resistance to lincomycin, which is characteristic of most clinical isolates with lincomycin resistance in Streptococcus pyogenes, has been studied. These strains grow within a defined concentration range of lincomycin (approximately 60 to 200 microgram/ml), or at lincomycin concentrations below the minimal inhibitory concentration for susceptible strains. It is shown that the zonal growth phenomenon is a stable phenotype and results from induction of resistance only within the zonal concentration range of lincomycin. These strains also possess inducible resistance to erythromycin which is nonzonal in character. One-step mutations to constitutive resistance have been isolated which are of two types: constitutive for lincomycin or for erythromycin, but not for both. Those strains with constitutive erythromycin resistance retain their zonal resistance for lincomycin. Mutants doubly constitutive for both lincomycin and erythromycin can be obtained by a second mutational step from either of the singly constitutive mutants. Satellite deoxyribonucleic acid has been shown to be present in the zonal resistant strains. A plasmid, pSM10419, of 14.9 megadaltons, has been isolated from one of the doubly constitutive mutants and used to jointly transform Streptococcus sanguis strain Challis to constitutive resistance to both lincomycin and erythromycin. From this, a multicopy plasmid of reduced size, pSM10 (5.4 megadaltons), which retains its resistance phenotype, has been isolated and mapped with restriction endonucleases HindIII (three sites), EcoRI (one site), KpnI (one site), and HpaI (one site). The staphylococcal plasmid pC221 (2.9 megadaltons; chloramphenicol resistant) has been fused to pSM10 at the EcoRI site resulting in a chimeric plasmid, pSM10221 (8.3 megadaltons), which retains resistance to chloramphenicol, erythromycin, and lincomycin. pSM10 is therefore suggestive as an effective cloning vehicle for the genus Streptococcus.
Certain norcarotenoids, which have recently been found as excretion products of freshwater cyanobacteria and algae, are potent inhibitors of different metabolic functions in heterotrophic bacteria. 6-Methylhept-5-en-2-one showed the strongest effects and acted as a noncompetitive inhibitor of both glucose uptake and respiration by aquatic isolates of Chromobacterium lividum and Arthrobacter sp. Inhibition of the heterotrophic potential of glucose uptake by 6-methylhept-5-en-2-one was characterized by considerably lower inhibitor constants for bacterial cultures (Ki = 0.4 and 1.6 microM) than for a river water sample (Ki = 186.0 microM).
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In a comparison on samples of muscular substance from 53 fattening bulls the extraction of intramuscular fat with a chloroform-methanol mixture yielded results about 1.23% higher than those obtained with the extraction with diethyl ether. This difference results from the extraction of additional water-soluble nitrogenous compounds by the chloroform-methanol mixture. These compounds were isolated by adding water to the chloroform-methanol extract; their analysis by means of chemical and spectroscopic methods revealed, among other compounds, creatinine and threonine. The fat values obtained for the ether extract were closely correlated with those found for the chloroform-methanol extract (r = 0.925). In a variant where water was added to the chloroform-methanol extract, the correlation was less close (r = 0.925). In a variant where water was added to the chloroform-methanol extract, the correlation was less close (r = 0.660). The chloroform-methanol extraction may be used instead of the ether extraction. A regression calculated from the present data permits, if required, to convert the values thus obtained into the values yielded by the ether extraction method. Apart from its high precision, the chloroform-methanol extraction has the special advantage that it requires relatively simple safety measures and that its energy demand is low.
This paper introduces a theoretical frame-work for characterizing and classifying simple parallel algorithms and systems with many inputs, for example an array of photoreceptors. The polynomial representation (Taylor series development) of a large class of operators is introduced and its range of validity discussed. The problems involved in the polynomial approximation of systems are also briefly reviewed. Symmetry properties of the input-output map and their implications for the system structure (i.e. its kernels) are studied. Finally, the computational properties of polynomial mappings are characterized.
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The venous anatomy of 22 autopsy specimens of human pancreas was examined by dissection and radiography after injection of gelatin agent. The most constant findings were the posterior superior pancreaticoduodenal vein draining to the portal vein and the anterior superior pancreaticoduodenal vein draining to the gastrocolic trunk and superior mesenteric vein. Both veins were identified in 21 and 20 of 22 cases, respectively. All other pancreatic veins varied considerably in their course. The normal findings in clinical selective pancreatic phlebography based on 148 examinations are described.
Pancreatic phlebography was performed in 67 patients with proven inflammatory or tumour disease in the region of the pancreas. The findings are described and the diagnostic value of the method is discussed.
In 33 patients with carcinoma of the head of the pancreas, both angiography and percutaneous transhepatic portography combined with selective phlebography of the pancreatic veins were performed. The tumour diagnosis was made in 28 patients by angiography and in 21 by phlebography. Correlation was found between extrapancreatic artery encasement, involvement of the main stems of the portal vein system and non-resectability of the tumour. In 5 patients venous involvement demonstrated by portography was the only indication of non-resectability of the tumours.
Based on 45 examinations the technique of selective catheterization of the pancreatic veins for blood sampling using percutaneous transhepatic approach to the portal vein is described. The results are compared with the angiographic findings in 16 patients with islet cell tumours of islet cell hyperplasia.