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S E Jorgensen

Publications and source records attributed to S E Jorgensen.

15 recordsLinked to original sources
PubMed2003

Effects of substrate concentrations on the growth of heterotrophic bacteria and algae in secondary facultative ponds.

This paper presents the effect of substrate concentration on the growth of a mixed culture of algae and heterotrophic bacteria in secondary facultative ponds (SFPs) utilizing settled domestic sewage as a sole source of organic carbon. The growth of the mixed culture was studied at the concentrations ranging between 200 and 800 mg COD/l in a series of batch chemostat reactors. From the laboratory data, the specific growth rate (micro) was determined using the modified Gompertz model. The maximum specific growth rate ( micro(max)) and half saturation coefficients (K(s)) were calculated using the Monod kinetic equation. The maximum observed growth rate ( micro(max)) for heterotrophic bacteria was 3.8 day(-1) with K(s) of 200 mg COD/l. The micro(max) for algal biomass based on suspended volatile solids was 2.7 day(-1) with K(s) of 110 mg COD/l. The micro(max) of algae based on the chlorophyll-a was 3.5 day(-1) at K(s) of 50mg COD/l. The observed specific substrate removal by heterotrophic bacteria varied between the concentrations of substrate used and the average value was 0.82 (mg COD/mg biomass). The specific substrate utilization rate in the bioreactors was direct proportional to the specific growth rate. Hence, the determined Monod kinetic parameters are useful for the definition of the operation of SFPs.

Bacteria↗
PubMed2001

Toward a consistent pattern of ecosystem theories.

Several ecosystem theories have been presented during the last 2-3 decades. Lately it has been possible to unite these theories into a consistent pattern. Intensive discussions at meetings have been the key to the formation of this pattern of ecosystem theories. Another driving factor has been the reformulation of E.P. Odum's attributes into three growth forms: growth of the physical structure (the biomass), growth of the network (more cycling, more linkages), and growth of information. An analysis of the growth forms shows that through-flow (power), ascendancy, and exergy storage are all increasing as a consequence of all three types of growth. However, exergy dissipation, entropy production, specific exergy (exergy/biomass), retention time, and the ratio indirect/direct effect only increases or decreases with one or two of the growth forms.

Ecosystem↗
PubMed1986

Effect of Escherichia coli hemolysin on permeability of erythrocyte membranes to calcium.

The extracellular hemolysin produced by porcine strains of E. coli effects a marked increase in the calcium permeability of erythrocyte membranes. This hemolysin promotes both calcium efflux from either calcium-loaded erythrocytes or erythrocyte ghosts and calcium accumulation during the pre-lytic period. Erythrocyte membrane calcium permeability was determined using either the radioisotope 45Ca or a calcium electrode. When similar concentrations of erythrocytes (35% packed cell volume) were treated with increasing amounts of hemolysin there was an increase in both the rate and the extent of calcium accumulation by the erythrocytes. These increases were due to increased numbers of erythrocytes becoming permeable to calcium as hemolysin concentrations increased, rather than increasing amounts of calcium being accumulated by individual erythrocytes. Hemolysins produced by porcine strains of E. coli from five geographical areas all increased calcium permeability of erythrocyte membranes.

Bacterial Proteins↗
PubMed1983

Calcium accumulation in human and sheep erythrocytes that is induced by Escherichia coli hemolysin.

The membrane permeability of both human and sheep erythrocytes is modified by an Escherichia coli-produced extracellular hemolysin. Alterations in membrane permeability were determined by measuring changes in the extracellular concentration of radiolabeled compounds that had been added to a 30-35% erythrocyte suspension. During the pre-lytic period, the E. coli hemolysin promotes calcium accumulation by both human and sheep erythrocytes. The concentration of calcium associated with the cells rises to a level that is approximately 1.5 (sheep) to 3 (human) times higher than that in a comparable volume of extracellular solution. Hemolysin also causes a rapid depletion of the high intracellular potassium levels normally present in human erythrocytes. That neither inulin, sucrose nor phosphate is accumulated by hemolysin-treated erythrocytes indicates that hemolysin makes the membrane selectively permeable to cations.

Animals↗
PubMed1983

Production of a bacteriolysin by a hemolytic Escherichia coli strain.

Nonhemolytic Escherichia coli were outnumbered by hemolytic E. coli within 24 h after being inoculated in a mixed culture at an initial ratio of 200 nonhemolytic to 1 hemolytic organism. The hemolytic strain was found to produce a cell-free, filterable substance which causes lysis of nonhemolytic E. coli B when grown in liquid cultures but not when grown on agar plates. The bacteriolysin is inactivated by boiling, by freezing and thawing, and by incubation with trypsin. The inability to inhibit growth on an agar plate, dependence on cell concentration for its effect, lysis of the sensitive cells, and appearance of phage particles in the cell lysates suggest that this substance is not like colicins or microcins previously described. After lysis of E. coli B, bacteriophage particles were visible in transmission electron micrographs of material pelleted by ultracentrifugation. However, no bacteriophage were observed in pellets from the bacteriolysin-containing supernatants before lysis of E. coli B. Failure to find bacteriophage in these preparations, and the fact that some bacteriolysin activity remains in the supernatant solution after centrifugation at 150,000 X g for 6.5 h, indicate that the bacteriolysin is not itself a bacteriophage. Exposure of E. coli B to UV light and mitomycin C did not induce production of a temperate phage. The properties of this system, in which a cell-free substance produced by one strain of bacteria causes lysis of another strain, appear to differ from those of the various types of bacteriocins and bacteriophages described to date.

Bacteriolysis↗
PubMed1982

The role of pressure damage in pathogenesis of the downer cow syndrome.

Experimental downer cows were produced by maintaining healthy cows in sternal recumbency for 6, 9, or 12 hours with the right pelvic limb positioned under the body. Halothane anesthesia was used to create this artificial parturient paresis-like position. In 8 of 16 experiments, cows were able to stand within 3 hours after anesthesia, but the others remained recumbent until death or euthanasia. There was no correlation between duration of the treatment and ability to stand after enforced recumbency. The appearance of the right pelvic limb of downer cows resembled the injured limbs of human patients with compartmental/crush syndrome, as well as the limbs of clinical downer cows. The affected limbs were swollen and held in rigid extension. Some animals which were able to stand also had swollen right pelvic limbs. Systemic signs of crush syndrome included dark yellow or brown urine suggestive of myoglobinuria, and marked elevation of serum creatine kinase enzyme levels. Highest creatine kinase levels were observed at 24 hours in the ambulatory group and at 48 hours in the downer group. Necropsy of downer animals revealed ischemic necrosis of the caudal thigh muscles and inflammation of the sciatic nerve caudal to the proximal end of the femur. Evidence of peroneal nerve damage was observed in at least 9 animals.

Anesthesia, General↗
PubMed1980

Effects of a single hit from the alpha hemolysin produced by Escherichia coli on the morphology of sheep erythrocytes.

Scanning electron micrographs of sheep erythrocytes showed that attachment of the alpha hemolysin produced by Escherichia coli resulted in the formation of spherocytes, with 10 to 20 small projections spaced relatively evenly over the surface of the erythrocyte membrane. This shape change was induced within 5 min after treatment. If the hemolysin concentration was reduced to a level which would lyse only a fraction of the total erythrocytes, the affected cells were easily identified against a background of normal, unaffected cells. Unlike sodium lauryl sulfate and other amphipathic agents which enter cell membranes and increase their flexibility, low concentrations of hemolysin did not provide protection against hypotonic hemolysis. These findings indicate that the surface projections were not the result of membrane expansion caused by incorporation of hemolysin into the outer portion of the lipid bilayer. The ability of a given amount of hemolysin to release a constant amount of hemoglobin in the presence of increasing concentrations of red cells confirmed that a single hit is sufficient for lysis. These results suggest that a single hemolysin molecule can bind to a sheep erythrocyte and trigger internal reactions which result in the derangement of membrane integrity at multiple sites on the surface. Confirmation of one-hit kinetics indicates that measurement of E. coli hemolysin activity should be carried out at low ratios of hemolysin to erythrocyte to decrease the possibility of multiple hits on a single cell.

Animals↗
PubMed1976

Studies on the origin of the alpha-haemolysin produced by Escherichia coli.

Synthesis of alpha-haemolysin by Escherichia coli was proportional to the amount of meat-broth factor present in the medium and not to bacterial growth. The meat-broth component required for the synthesis of haemolysin was found to have several physical and chemical properties in common with alpha-haemolysin itself. Both molecules are trypsin-sensitive, acidic substances with similar elution volumes when subjected to gel-filtration chromatography with Sepharose 6B. Isotopic labelling experiments in which the bacteria were grown on 14C-labelled meat broth showed that partially purified haemolysin preparations contained molecules of mammalian origin. Similar experiments in which 14C-glucose was used to label bacterial molecules showed that little or no material of bacterial origin was present in the haemolysin preparation. These data suggest that alpha-haemolysin may be produced by bacterial modification of a molecule present in meat broth rather than by synthesis de novo within the bacterial cell.

Culture Media↗
PubMed1976

Studies on the mode of action of clomiphene citrate.

In order to further investigate the mode of action of clomiphene citrate, 5 oophorectomized women in the age range 28 to 41 years were followed with weekly determinations of serum FSH and LH for 20 weeks after the operation. They received no treatment during the first 4 weeks but during the next 16 weeks they were given estradiol 2 mg X 2 daily orally, and from the 12th to the 16th week in addition clomiphene citrate 50 mgX2 daily. The high level of FSH after the oophorectomy decreased gradually during the treatment with estradiol alone, but this effect was partly neutralized by clomiphene citrate, as we observed a significant increase in FSH within 1 week of initiating treatment with clomiphene citrate. On the other hand, we did not find any significant changes in FSH within 4 weeks after treatment with clomiphene citrate was discontinued. The high level of LH after oophorectomy did not show any significant changes during the whole treatment period. It is concluded that clomiphene citrate primarily stimulated FSH secretion, most probably by a competition with estradiol for the receptor sites in the hypothalamus or the pituitary. In addition, it is concluded that clomiphene citrate has a prolonged effect, probably because of a tight binding to the receptor sites.

Administration, Oral↗
PubMed1970

Isolation of bacteriophage T4 mutants defective in the ability to degrade host deoxyribonucleic acid.

A method was devised for identifying nonlethal mutants of T4 bacteriophage which lack the capacity to induce degradation of the deoxyribonucleic acid (DNA) of their host, Escherichia coli. If a culture is infected in a medium containing hydroxyurea (HU), a compound that blocks de novo deoxyribonucleotide biosynthesis by interacting with ribonucleotide reductase, mutant phage that cannot establish the alternate pathway of deoxyribonucleotide production from bacterial DNA will fail to produce progeny. The progeny of 100 phages that survived heavy mutagenesis with hydroxylamine were tested for their ability to multiply in the presence of HU. Four of the cultures lacked this capacity. Cells infected with one of these mutants, designated T4nd28, accumulated double-stranded fragments of host DNA with a molecular weight of approximately 2 x 10(8) daltons. This mutant failed to induce T4 endonuclease II, an enzyme known to produce single-strand breaks in double-stranded cytosine-containing DNA. The properties of nd28 give strong support to an earlier suggestion that T4 endonuclease II participates in host DNA degradation. The nd28 mutation mapped between T4 genes 32 and 63 and was very close to the latter gene. It is, thus, in the region of the T4 map that is occupied by genes for a number of other enzymes, including deoxycytidylate deaminase, thymidylate synthetase, dihydrofolate reductase, and ribonucleotide reductase, that are nonessential to phage production in rich media.

Carbon Isotopes↗
PubMed1969

Nucleoside triphosphate termini from RNA synthesized in vivo by Escherichia coli.

Alkaline hydrolyzates of RNA made in vivo by Escherichia coli contain ribonucleoside-3'-monophosphate-5'-triphosphates. These probably arise by hydrolysis of the initial nucleoside triphosphate from the 5' terminus of the nascent RNA chains. Logarithmically growing cultures, labeled for 45 seconds with (32)P-labeled phosphate, yield about 2000 molecules of labeled tetraphosphate per cell, this yield increasing only slightly with continued labeling. Only the tetraphosphates of adenosine and guanosine have been found in Escherichia coli, and these two are present in approximately equal amounts.

Adenine Nucleotides↗