PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-12 (12)
 

Clipboard (0)
None

Select a Filter Below

Journals
Authors
more »
Year of Publication
more »
1.  A new interventional technique for percutaneous treatment of drainage-resistant liver abscess 
The British Journal of Radiology  2010;83(993):e195-e197.
The objective of this case report is to describe a device that can be used as a minimally invasive alternative for the treatment of drainage-resistant liver abscess. The device uses pulse lavage to fragment and evacuate the semi-solid contents of a liver abscess. The treatment of liver abscesses consists of percutaneous drainage, antibiotics and treatment of the underlying cause. This approach can be ineffective if the contents of the abscess cavity are not liquid, and in those cases open surgery is often needed. Here, we describe for the first time a new minimally invasive technique for treating persistent liver abscesses. A patient developed a liver abscess after a hepatico-jejunostomy performed as a palliative treatment for an unresectable pancreatic head carcinoma. Simple drainage by a percutaneously placed pig-tail catheter was insufficient because of inadequate removal of the contents of the abscess cavity. After dilatation of the drain tract the persistent semi-solid necrotic contents were fragmented by a pulsed lavage device, after which the abscess healed uneventfully. The application of pulsed lavage for debridement of drainage-resistant liver abscesses proved to be an effective and minimally invasive alternative to open surgery.
doi:10.1259/bjr/69471744
PMCID: PMC3473396  PMID: 20739342
2.  Isolation of Alcaligenes sp. strain L6 at low oxygen concentrations and degradation of 3-chlorobenzoate via a pathway not involving (chloro)catechols. 
Isolations of 3-chlorobenzoate (3CBA)-degrading aerobic bacteria under reduced O2 partial pressures yielded organisms which metabolized 3CBA via the gentisate or the protocatechuate pathway rather than via the catechol route. The 3CBA metabolism of one of these isolates, L6, which was identified as an Alcaligenes species, was studied in more detail. Resting-cell suspensions of L6 pregrown on 3CBA oxidized all known aromatic intermediates of both the gentisate and the protocatechuate pathways. Neither growth on nor respiration of catechol could be detected. Chloride production from 3CBA by L6 was strictly oxygen dependent. Cell-free extracts of 3CBA-grown L6 cells exhibited no catechol dioxygenase activity but possessed protocatechuate 3,4-dioxygenase, gentisate dioxygenase, and maleylpyruvate isomerase activities instead. In continuous culture with 3CBA as the sole growth substrate, strain L6 demonstrated an increased oxygen affinity with decreasing steady-state oxygen concentrations.
PMCID: PMC168026  PMID: 8779583
3.  Utilization of Organic Nitrogen Sources by Two Phytoplankton Species and a Bacterial Isolate in Pure and Mixed Cultures 
Algal production of dissolved organic carbon and the regeneration of nutrients from dissolved organic carbon by bacteria are important aspects of nutrient cycling in the sea, especially when inorganic nitrogen is limiting. Dissolved free amino acids are a major carbon source for bacteria and can be used by phytoplankton as a nitrogen source. We examined the interactions between the phytoplankton species Emiliania huxleyi and Thalassiosira pseudonana and a bacterial isolate from the North Sea. The organisms were cultured with eight different amino acids and a protein as the only nitrogen sources, in pure and mixed cultures. Of the two algae, only E. huxleyi was able to grow on amino acids. The bacterium MD1 used all substrates supplied, except serine. During growth of MD1 in pure culture, ammonium accumulated in the medium. Contrary to the expectation, the percentage of ammonium regenerated from the amino acids taken up showed no correlation with the substrate C/N ratio. In mixed culture, the algae grew well in those cultures in which the bacteria grew well. The bacterial yields (cell number) were also higher in mixed culture than in pure culture. In the cultures of MD1 and T. pseudonana, the increase in bacterial yield (number of cells) over that of the pure culture was comparable to the bacterial yield in mixed culture on a mineral medium. This result suggests that T. pseudonana excreted a more-or-less-constant amount of carbon. The bacterial yields in mixed cultures with E. huxleyi showed a smaller and less consistent difference than those of the pure cultures of MD1. It is possible that the ability of E. huxleyi to use amino acids influenced the bacterial yield. The results suggest that interactions between algae and bacteria influence the regeneration of nitrogen from organic carbon and that this influence differs from one species to another.
PMCID: PMC201516  PMID: 16349256
4.  Influence of hydrogen-consuming bacteria on cellulose degradation by anaerobic fungi. 
Applied and Environmental Microbiology  1990;56(12):3793-3797.
The presence of methanogens Methanobacterium arboriphilus, Methanobacterium bryantii, or Methanobrevibacter smithii increased the level of cellulose fermentation by 5 to 10% in cultures of several genera of anaerobic fungi. When Neocallimastix sp. strain L2 was grown in coculture with methanogens the rate of cellulose fermentation also increased relative to that for pure cultures of the fungus. Methanogens caused a shift in the fermentation products to more acetate and less lactate, succinate, and ethanol. Formate transfer in cocultures of anaerobic fungi and M. smithii did not result in further stimulation of cellulolysis above the level caused by H2 transfer. When Selenomonas ruminatium was used as a H2-consuming organism in coculture with Neocallimastix sp. strain L2, both the rate and level of cellulolysis increased. The observed influence of the presence of methanogens is interpreted to indicate a shift of electrons from the formation of electron sink carbon products to H2 via reduced pyridine nucleotides, favoring the production of additional acetate and probably ATP. It is not known how S. ruminantium exerts its influence. It might result from a lowered production of electron sink products by the fungus, from consumption of electron sink products or H2 by S. ruminantium, or from competition for free sugars which in pure culture could exert an inhibiting effect on cellulolysis.
PMCID: PMC185069  PMID: 2082826
5.  Comparison of sickness absence in Belgian, German, and Dutch firms. 
International comparisons of sickness absence rates are difficult to make because of different national social security arrangements or recording procedures. Therefore a cross national study of sickness absence in Belgium, West Germany, and the Netherlands focused firstly on "contextual" aspects of sickness absence such as work incapacity benefit schemes, job security regulations, and the role of occupational physicians. Substantial differences were observed in regulations, local definitions, and available data. Those differences provide hypotheses for possibly divergent absence levels as well. For instance, Belgium shows the most diversified control procedures, the lowest level of sickness benefits, and the most rigid qualifying criteria for invalidity benefits. Sickness absence data were obtained from companies of four different clusters, each consisting of a comparable Belgian, German, and Dutch organisation. Conceptual, administrative, and statistical sources of bias were accounted for by selecting companies which resemble each other as to their product, production process, size, and geographical location: by using standardised definitions, absence data, and indices (observation period 1 January 1980 to 1 January 1982); and by measuring population variables to eliminate obvious explanations in terms of workforce composition. Controlled comparisons in these multiple clusters showed considerable and consistent differences in sickness absence rates. Whereas Belgian employees had 20.3 days of sickness absence (standardised for sex, age, and occupation) a year, German and Dutch employees had 28.5 and 39.1 days off a year respectively. Factors that might account for these differences are discussed.
PMCID: PMC1007701  PMID: 3730302
6.  Role of Megasphaera elsdenii in the Fermentation of dl-[2-13C]lactate in the Rumen of Dairy Cattle 
Since Megasphaera elsdenii ferments a variable part of dl-lactate to butyrate, measurement of the percentage of dl-lactate fermented to propionate via the acrylate pathway in rumen contents will underestimate the participation of M. elsdenii in the dl-lactate fermentation. The percentage of dl-[2-13C]lactate fermented via the acrylate pathway and the percentage of dl-lactate fermented to butyrate can be measured with 13C-FT (Fourier transform)-nuclear magnetic resonance. On the average, the contribution of M. elsdenii to dl-lactate fermentation in the rumen of dairy cattle was found to be 74% (standard deviation, 13%), but differed with animal or diet. After feeding a cow readily fermentable carbohydrates, the contribution of M. elsdenii to the fermentation of dl-lactate increased as a consequence of catabolite repression in other dl-lactate-fermenting bacteria.
PMCID: PMC244077  PMID: 16345862
7.  Inhibition of nitrate reduction in some rumen bacteria by tungstate. 
Tungstate prevented the formation of active nitrate reductase in growing rumen bacteria capable of nitrate reduction, but did not directly inhibit the enzyme activity of all strains tested.
PMCID: PMC291540  PMID: 7190809
8.  Calculation of Km and Vmax from Substrate Concentration Versus Time Plot 
A simple method for the calculation of kinetic parameters (Km, Vmax) under conditions of changing substrate concentrations is presented. An application of the method to detect shifts in groups involved in the utilization of a substrate in a mixed microbial culture is given.
PMCID: PMC243575  PMID: 16345452
9.  Relative Significance of Exogenous and De Novo Synthesized Fatty Acids in the Formation of Rumen Microbial Lipids In Vitro † 
Mixed rumen microorganisms (MRM) or suspensions of rumen Holotrich protozoa obtained from a sheep were incubated anaerobically with [1-14C]linoleic acid, [U-14C]glucose, or [1-14C]acetate. With MRM, the total amount of fatty acids present did not change after incubation. An increase in fatty acids esterified into sterolesters (SE) and polar lipids at the expense of free fatty acids was observed. This effect was intensified by the addition of fermentable carbohydrate to the incubations. Radioactivity from [1-14C]linoleic acid was incorporated into SE and polar lipids with both MRM and Holotrich protozoa. With MRM the order of incorporation of radioactivity was as follows: SE > phosphatidylethanolamine > phosphatidylcholine. With Holotrich protozoa, the order of incorporation was phosphatidylcholine > phosphatidylethanolamine > SE. With MRM the radioactivity remaining in the free fatty acids and that incorporated into SE was mainly associated with saturated fatty acids, but a considerable part of the radioactivity in the polar lipids was associated with dienoic fatty acids. This effect of hydrogenation prior to incorporation was also noted with Holotrich protozoa but to a much lesser extent. Small amounts of radioactivity from [U-14C]glucose and [1-14C]acetate were incorporated into rumen microbial lipids. With protozoa incubated with [U-14C]glucose, the major part of incorporated radioactivity was present in the glycerol moiety of the lipids. From the amounts of lipid classes present, their radioactivity, and fatty acid composition, estimates were made of the amounts of higher fatty acids directly incorporated into microbial lipids and the amounts synthesized de novo from glucose or acetate. It is concluded that the amounts directly incorporated may be greater than the amounts synthesized de novo.
PMCID: PMC242772  PMID: 623468
10.  Lipid-phase transitions of the strictly anaerobic bacteria Veillonella parvula and Anaerovibrio lipolytica. 
Journal of Bacteriology  1975;124(3):1522-1528.
As a basis for physicochemical studies on the membranes of the strictly anaerobic bacteria Veillonella parvula, Anaerovibrio lipolytica, and Megasphaera elsdenii, the fatty acyl and alk-1-enyl moieties on the phosphoglycerides of these organism were characterized. Uncommon is the high proportion of a heptadecenoic acyl and alk-1-enyl moiety in these three lactate-fermenting bacteria. In contrast to V. parvula and A. lipolytica, M. elsdenii contains high amounts of branched-chain acyl and alk-1-enyl moieties. Freeze-etching electron microscopy showed that the lipids of the plasma membranes of V. parvula and A. lipolytica go from the liquid crystalline to the gel state upon lowering of the temperature, indicating that the membrane lipids are predominantly in the fluid state. No lipid-protein segregation could be detected in the plasma membrane of M. elsdenii. This can be explained by the abundance of branched-chain fatty acyl and alk-1-enyl residues in the membranes of this organism which may prevent lipid-protein segregation during the lipid-phase transition.
Images
PMCID: PMC236067  PMID: 1194242
11.  Parameters of Rumen Fermentation in a Continuously Fed Sheep: Evidence of a Microbial Rumination Pool 
Applied Microbiology  1971;22(6):1104-1113.
The feed and feces of a continuously fed sheep were analyzed for carbon, hydrogen, and nitrogen, with oxygen as the remainder. The daily feed-feces weight difference was used as the reactant in an equation representing the rumen fermentation. The measured products were the daily production of volatile fatty acids (VFA), CH4, CO2, and ammonia. The carbon unaccounted for was assumed to be in the microbial cell material produced in the rumen and absorbed before reaching the feces. The ratio of C to H, O, and N in bacteria was used to represent the elemental composition of the microbes formed in the rumen fermentation, completing the following equation:C20.03H36.99O17.406N1.345 + 5.65 H2O → C12H24O10.1 + 0.83 CH4 VFA + 2.76 CO2 + 0.50 NH3 + C4.44H8.88O2.35N0.785 microbial cells absorbed With C arbitrarily balanced and O balanced by appropriate addition of water, any error is reflected in the H. The H recovery was 98.5%. The turnover rate constant for rumen liquid equilibrating with polyethylene glycol (PEG) was 2.27 per day. Direct counts and volume measurements of the individual types of bacteria and protozoa in the rumen were used to calculate the total microbial cell volume in the rumen, not equilibrating with it. The dry matter in the rumen (582 g) and the nitrogen content (12.05) of the microbes in the rumen were estimated, the latter constituting 85% of the measured N in the rumen. Calculations for rumen dry matter and nitrogen turning over at the PEG rate introduce big discrepancies with other parameters; a rumination pool must be postulated. Its size and composition are estimated. Arguments are presented to support the view that dry matter and some of the microbes, chiefly the protozoa, do not leave the rumen at the PEG rate. One experiment with the same sheep fed twice daily showed significantly less production of microbial cells than did the continuous (each 2 hr) feeding. Analysis of the microbial cell yield suggests that, on the basis of 11 mg of cells per adenosine triphosphate molecule, a maximum of six adenosine triphosphate molecules could have been formed from each molecule of hexose fermented.
PMCID: PMC376493  PMID: 5167618
12.  Isolation, Culture, and Fermentation Characteristics of Selenomonas ruminantium var. bryanti var. n. from the Rumen of Sheep 
Journal of Bacteriology  1971;105(3):820-825.
Large forms of Selenomonas sp. were isolated from the sheep rumen on a rumen fluid-glucose-agar medium by using a differential centrifugation technique to purify the inoculum. The cells from the six isolated strains were curved, gram-negative, strictly anaerobic crescents, and rapidly motile by flagella attached to the concave side of the cell. One or more of the volatile fatty acids were essential for growth. None of the strains produced indole or reduced nitrate. All strains grew on fructose, glucose, mannose, cellobiose, maltose, sucrose, and salicin. Fermentation end products from glucose were mainly lactate, acetate, propionate, and formate. Small amounts of succinate were formed. The final pH in a glucose medium ranged between 4.3 and 4.5. On the basis of the sugar fermentation characteristics and the capacity to form hydrogen sulfide from cysteine, it is suggested that one of the strains is a large form of Selenomonas ruminantium. The other five strains are designated S. ruminantium var. bryanti, var. n.
Images
PMCID: PMC248505  PMID: 4323298

Results 1-12 (12)