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At least 757 records · Page 42Linked to original sources
PubMed1995

Value of radionuclide rest and exercise left ventricular ejection fraction in assessing survival of patients after thrombolytic therapy for acute myocardial infarction: results of Thrombolysis in Myocardial Infarction (TIMI) phase II study. The TIMI Study Group.

OBJECTIVES: This study sought to determine the prognostic value of rest and exercise left ventricular ejection fraction in patients receiving thrombolytic therapy as part of the Thrombolysis in Myocardial Infarction (TIMI) trial. BACKGROUND: In the prethrombolytic era, ejection fraction at rest as well as during exercise was an important prognostic index in patients recovering from acute myocardial infarction. The prognostic value of these measurements in the thrombolytic era is not clear. METHODS: As part of the TIMI II protocol, we obtained radionuclide left ventricular ejection fraction at rest and during symptom-limited submaximal supine exercise. Measurements were related to 1-year all-cause as well as cardiac mortality. In addition, the relation between ejection fraction obtained at rest and 1-year cardiac mortality in this study was compared with the relation established previously in the prethrombolytic era by the Multicenter Postinfarction Research Group. RESULTS: A distinct relation was noted between left ventricular ejection fraction at rest and all-cause mortality. The highest mortality rate (9.9%) was noted in patients with an ejection fraction < 30%. Those not undergoing a study had a 1-year mortality rate of 6.2%. Peak exercise ejection fraction provided prognostic information similar to that of rest ejection fraction. Likewise, change in ejection fraction from rest to exercise did not appreciably improve prognostic impact. CONCLUSIONS: Rest left ventricular ejection fraction is an important prognostic index in patients receiving thrombolytic therapy. Peak exercise ejection fraction and the change in ejection fraction from rest to exercise do not provide appreciable prognostic data beyond those obtained at rest. Patients unable to exercise or those not having a rest study have a poor prognosis. When compared with the Multicenter Postinfarction Research Group data, there was strong evidence of a difference in survival in the two studies. At any level of ejection fraction, mortality was lower in TIMI II patients than in patients in the prethrombolytic era.

Aged↗
PubMed2005

Contribution of left ventricular diastolic dysfunction to heart failure regardless of ejection fraction.

Heart failure (HF) has been classified as systolic and diastolic based on the left ventricular ejection fraction. We hypothesized that left ventricular diastolic dysfunction is an important element of HF regardless of ejection fraction. Two hundred six patients who had clinical HF were compared with 72 age-matched controls. Diastolic dysfunction, as assessed by the mitral filling pattern and tissue Doppler imaging, was present in >90% of patients who had HF regardless of ejection fraction and was more frequent and severe than in age-matched controls (p <0.001). In patients who had HF, B-type natriuretic peptide correlated with diastolic dysfunction (r = 0.62, p <0.001) but not with ejection fraction or end-diastolic volume index (EDVI). The degree of diastolic dysfunction influenced survival rate (risk ratio 1.64, p <0.05), whereas ejection fraction and EDVI did not. Systolic function measured by systolic mitral annular velocity was decreased in patients who had HF and an ejection fraction </=0.40 (4.8 +/- 1.1 cm/s) and, to a lesser extent, an ejection fraction >/=0.50 (6.6 +/- 1.8 cm/s) compared with control subjects (8.0 +/- 2.1 cm/s, p <0.01). Patients who had HF and an ejection fraction >/=0.50 had an increased ratio of ventricular mass to EDVI. Patients who had HF and an ejection fraction </=0.40 had increased left ventricular EDVI. Thus, regardless of ejection fraction, patients who have HF also have diastolic dysfunction. Diastolic dysfunction is a better predictor of B-type natriuretic peptide levels and mortality than ejection fraction or left ventricular EDVI. In addition to diastolic dysfunction, HF with an ejection fraction >/=0.50 is associated with mild systolic dysfunction and an increased ratio of left ventricular mass to EDVI. In HF with an ejection fraction </=0.40, systolic dysfunction and left ventricular dilation accompany diastolic dysfunction.

Aged↗
PubMed2005

Free radical scavenging and apoptotic effects of Cordyceps sinensis fractionated by supercritical carbon dioxide.

Supercritical carbon dioxide (SC-CO2) was used as the elution solvent for fractioning ethanolic extract (E) of Cordyceps sinensis (CS), a traditional Chinese herbal remedy, into R, F1, F2, and F3 fractions. This extractive fractionation method is amenable to large scale and is nontoxic. These four fractions were characterized in terms of total polysaccharides and cordycepin concentrations, scavenging ability of free radicals, and anti-tumor activities. Experimental results demonstrated that fractionation altered the distributions of total polysaccharides and cordycepin in fractions. Fraction R was the most active fraction to scavenge free radicals and inhibit the proliferation of carcinoma cells, followed by the fraction F1 and the extract E. The effect of scavenging on 1,1-diphenyl-2-picryl hydrazyl (DPPH) of CS extract and fractions at 2 mg/ml was R (93%), F1 (75%), E (66%), F2 (47%), and F3 (27%). The IC50 (50% cell growth inhibitory concentration) of tumor cell proliferation and colony formation on human colorectal (HT-29 and HCT 116) and hepatocellular (Hep 3B and Hep G2) carcinoma cells by fraction R were around 2 microg/ml. Conversely, R did not affect the growth of normal dividing human peripheral blood mononuclear cells (PBMC) by exhibiting a large value of IC50 over 200 microg/ml. Accumulation of tumor cells at sub-G1 phase and the fragmentation of DNA, typical features of programmed cell death, were observed in a time and dose dependent manner. Scavenging of free radicals and anti-cancer activity (value of IC50) correlated closely with the quantities of polysaccharides (Spearman's rho=0.901 and -0.870, respectively). Taken together, our findings suggest that fraction R, obtained by SC-CO2 fluid extractive fractionation, showed strong scavenging ability and selectively inhibited the growth of colorectal and hepatocellular cancer cells by the process of apoptosis.

Apoptosis↗
PubMed2005

Visually estimated left ventricular ejection fraction by echocardiography is closely correlated with formal quantitative methods.

BACKGROUND: Simpson ejection fraction, wall motion score index, atrioventricular (AV) plane displacement and fractional shortening are all established formal echocardiographic methods for the assessment of left ventricular systolic function. Visually estimated (eyeballing) ejection fraction may be considered somewhat more subjective, although shown to correlate well with radionuclide ventriculography. We aimed to explore if echocardiographic eyeballing ejection fraction is comparable to formal methods for the evaluation of left ventricular systolic function. METHODS: We assessed 89 consecutive patients after myocardial infarction or before coronary angiography. Eyeballing ejection fraction and wall motion score index were evaluated in the long-axis, short-axis and apical four- and two-chamber views. Simpson ejection fraction and AV plane displacement were assessed in the apical views. Fractional shortening was measured in the parasternal long-axis view. The respective systolic function measurements were in each patient made at different time points by a single investigator, masked to prior results. RESULTS: All formal methods correlated significantly with eyeballing ejection fraction (p<0.001): AV plane displacement, R=0.647; FS, R=0.684; four-chamber Simpson ejection fraction, R=0.857; biplane Simpson ejection fraction, R=0.898; and wall motion score index, R=0.919. CONCLUSION: Eyeballing ejection fraction correlated closely with all formal methods and the correlation coefficient improved with the reliability of the formal method. This finding is in concordance with prior studies, indicating that eyeballing ejection fraction may be the most accurate echocardiographic method for the assessment of left ventricular systolic function. Since it is readily and quickly performed, eyeballing ejection fraction could be used for routine echocardiography instead of formal methods.

Adult↗
PubMed2003

Treatability of organic fractions derived from secondary effluent by reverse osmosis membrane.

Dissolved organic matters (DOMs) from two batches of secondary effluent collected from a local water reclamation plant were fractionated using column chromatographic method with non-ionic resins XAD-8, AG MP-50 and IRA-96. Seven isolated fractions were obtained from the fractionation study and these fractions were quantified using DOC, UV(254) and SUVA values. The fractionation study revealed that the secondary effluent samples comprised about 47.3-60.6% of hydrophobic and 39.4-52.7% of hydrophilic solutes. The treatability of each isolated fraction was investigated by subjecting each fraction to reverse osmosis (RO) treatment individually. It was noted that RO process could achieve high DOC rejections for acid and neutral fractions (ranging from 80% to 98% removal) probably due to the negative charge of RO membrane. The results obtained also indicated that hydrophobicity of DOMs is significant in determining treatability of organic species by RO process. The performance of RO in terms of DOC rejection of un-fractionated secondary effluent was also investigated to assess possible effects of interactions among organic fractions on their treatability by RO process. It was noted that DOC rejection associated with the un-fractionated secondary effluent was generally higher (ranging from 2% to 45%) than the corresponding rejection obtained from each individual fraction isolated from the secondary effluent. This finding suggested there is a beneficial interaction among the fractions that in turn has contributed towards a better overall DOC rejection performance by RO treatment.

Chromatography↗
PubMed2001

Photoinductive properties of soil humic acids and their fractions obtained by tandem size exclusion chromatography-polyacrylamide gel electrophoresis.

Humic acids (HAs) from three soils of different origin (Chernozem, Ferralsol and Ranker) have been fractionated by coupling size exclusion chromatography (SEC) and polyacrylamide gel electrophoresis (PAGE) on three fractions (fractions A, B, C + D) with different molecular sizes (MSs) and exactly defined electrophoretic mobility (EM). Fractions identically marked had similar EM and MS, independently of HA sources. The photoinductive properties of the whole HAs and their fractions were compared by studying the photoinduced transformation of fenuron at 365 nm. High MS fractions A and B appeared to exhibit poor photoinductive activities compared to the whole HAs, whereas low MS fraction C + D in Chernozem and Ranker were more efficient than the whole HAs. A fourth intermediary fraction containing a mixture of fractions B and C + D with small amount of D was shown to photoinduce poorly the transformation of fenuron. It was therefore concluded that the molecules capable of photoinducing the transformation of fenuron were mainly contained in fraction D. Fluorescence properties of Chernozem HA and its fractions have been tested. Fraction C + D exhibited a very similar fluorescence emission spectrum in comparison with the whole HA and in contrast, the fractions A and B emitted very weakly.

Chromatography↗
PubMed2000

The variation of mass and disinfection by-product formation potential of dissolved organic matter fractions along a conventional surface water treatment plant.

Dissolved organic matter (DOM) influences many aspects of water treatment, including the formation of potentially harmful disinfection by-products (DBPs) when disinfectants are applied. DOM from a conventional surface water treatment plant (WTP) in Northern New Jersey was isolated and fractionated using resin adsorption chromatography into six different fractions. These fractions are operationally categorized as hydrophobic acid, hydrophobic neutral, hydrophobic base, hydrophilic acid, hydrophilic neutral and hydrophilic base. The hydrophilic acid fraction was found to be the most abundant fraction in the source water. The hydrophilic neutral, hydrophilic acid and hydrophobic acid fractions had the highest removal efficiency through the WTP (about 65%). The variation and removal effectiveness of each fraction along the WTP was studied. Seven-day chlorine DBP formation potential (FP) tests were performed on all DOM fractions through the WTP. For the source water studied, the hydrophilic acid fraction was found to be the most reactive precursor to the trihalomethane (THM) formation. The hydrophobic neutral fraction was found to be the fraction of concern with respect to the FP of haloacetic acids (HAAs) class of DBPs. The FP of each fraction's class of DBPs was found to be amenable for reduction along the treatment train, specifically by coagulation/sedimentation. The fractionated approach concept showed to be very beneficial in the study of DBP precursors and their effective removal by physical and chemical treatment.

Adsorption↗
PubMed1997

Impact of radiation therapy fraction size on local control of early glottic carcinoma.

PURPOSE: Different radiotherapy fractionation schedules were used over a 10-year period to treat patients with early squamous cell carcinoma of the vocal cords at McGill University. A retrospective analysis was performed to study the effect of fraction size on local control in this group of patients. METHODS AND MATERIALS: A total of 126 previously untreated patients with T1 invasive squamous cell carcinoma of the true vocal cords were irradiated between January 1978 and December 1988 in the Department of Radiation Oncology at McGill University. All patients received megavoltage irradiation, 94 patients received daily fractions > 2 Gy (64 patients received 50 Gy with once-daily 2.5-Gy fractions, and 30 received 65.25 Gy in 29 fractions of 2.25 Gy each), and 32 patients were treated to a dose of 66 Gy in 33 fractions with 2 Gy/fraction. Patients' characteristics of prognostic importance were equally distributed between the two fractionation groups. RESULTS: At a median follow-up of 84 months, the 10-year disease-free survival and overall survival were 76% and 93%, respectively. Local control for patients treated with > 2 Gy fraction was 84%, compared to 65.6% for those treated with 2-Gy fractions (p = 0.026). Among the prognostic factors tested, such as gender, age, stage, anterior and posterior commissure involvement, smoking history, and fraction size, the latter was the only significant predictor of local control for the whole group of patients in univariate (p = 0.041) and multivariate (p = 0.023) analysis. There was no observed difference in the incidence of complications between the two fractionation groups. CONCLUSIONS: From the results of this retrospective review of patients treated with radiotherapy for T1 true vocal cord cancer, and within the range of total doses and overall treatment times used in our patients, it was found that fractionation schedules using daily fraction size > 2 Gy are associated with a better local control than schedules delivering 2 Gy/fraction, with no increase in toxicity.

Carcinoma, Squamous Cell↗
PubMed2003

Broncho-vasodilatory activity of fractions and pure constituents isolated from Bacopa monniera.

The present study demonstrates that various fractions and sub-fractions isolated from Bacopa monniera produced significant inhibition of carbachol-induced bronchoconstriction, hypotension and bradycardia in anaesthetized rats. All these showed more potency towards inhibition of tracheal pressure compared to either blood pressure or heart rate. The sub-sub fraction and compound 1 caused greater inhibition of tracheal pressure and heart rate compared to blood pressure. Thus, overall bioassay-directed fractionation of B. monniera improved the bronchodilatory activity in various fractions and compound 1 (2-219x) in anaesthetized rats. In vitro, the KCl-induced contraction was equally inhibited by crude extract, petroleum ether and methanol fractions on trachea suggesting bronchodilatory activity remained the same in fractions. On pulmonary artery petroleum ether, dichloromethane and methanol fractions produced 2-2.6 times more vasodilatation compared to crude extract of B. monniera. Subsequent sub-fractions failed to show the existence of broncho-vasodilatory activity, however, the CHCl(3)/MeOH sub-fraction significantly reduced the acetylcholine-induced contraction on ileum. Both the methanol fraction and CHCl(3)/MeOH sub-fraction caused marked reduction of barium chloride-, potassium chloride- and calcium chloride-induced contraction on guinea-pig ileum, indicating their interference with Ca(2+) ion movement. Thus, it may be concluded that various fractions derived from B. monniera possess broncho-vasodilatory activity, which is attributed mainly to inhibition of calcium ions.

Animals↗
PubMedDate not supplied

Surface markers and biological functions of PMNC fractionated by countercurrent centrifugal elutriation.

Peripheral blood mononuclear cells (PMNC) were separated by countercurrent centrifugal elutriation (CCE) in PBS-EDTA medium into 13 fractions. Properties associated with B cells were restricted mainly to the first fractions (F2 and F4) while those associated with T cells were confined to fractions F4, F6 and F8. The final fraction (FF) contained more than 90% monocytes while fraction F10 contained 40% monocytes and 60% null cells, and F12 contained 50% monocytes and 50% null cells. Natural killer (NK) cell activity against K-562, a human erythroleukaemia cell line, and against an adherent undifferentiated sarcoma target, was distributed between fractions F6 and F8. Using electron and scanning microscopy and a new single cell liquid cytotoxic assay, we studied membrane interaction and binding of the CCE fractionated cells with the 2 targets. Effector/target cell conjugates revealed interdigitations in the area of cell contact but no membrane fusion, although certain effector cells had a distinct large granulocytic lymphocyte morphology. Furthermore, different cell types from different fractions were able to bind to the targets although the killing was associated with certain fractions only. When purified monocytes from fraction FF were added to F6 and F8, NK activity against both targets was depressed. This inhibition was not reversed by indomethacin, and binding of the targets to the effector cells was unaffected. CCE is a powerful technique which allows the fractionation of PMNC without altering their biological functions, contrary to what is seen with nylon wool or dextran fractionation. In this report, the activity associated with CCE fractions is studied and discussed.

Antibody-Producing Cells↗
PubMed1976

The incorporation of radioactive fatty acids and of radioactive derivatives of glucose into the phospholipids of subsynaptosomal fractions of cerebral cortex.

1. Crude synaptosomal fractions (P2) from guinea-pig cerebral cortex were incubated in a Krebs-glucose medium containing labelled fatty acids and [3H]glucose. After the shortest incubation period (7.5 min) a high percentage (50-80%) of the total radioactive fatty acids was found in the P2 fractions. 2. After the incubation, the synaptosomal fractions were submitted to hypo-osmotic disruption and subsynaptosomal fractionation was carried out by using discontinuous-sucrose-gradient centrifugation. The specific radioactivities of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol were determined in fractions D (synaptic vesicles), E (microsomal preparation) and H (disrupted synaptosomes), as were the specific activities of a number of marker enzymes and the distribution of acetylcholine. 3. By using [14C]oleate, [14C]arachidonate, [3H]palmitate and [3H]glucose, the order to specific radioactivities in fraction D was found to be: phosphatidylinositol greater than phosphatidylcholine greater than phosphatidylserine greater than phosphatidylethanolamine. 4. The specific radioactivities of phosphatidylcholine and phosphatidylethanolamine were always higher in fraction D than in fraction E. As fraction E had higher specific activities of several membrane marker enzymes, the enhanced labelling found in fraction D was considered to be localized in the synaptic vesicles. In this fraction, phosphatidylinositol made particularly large contributions to the total phospholipid labelling derived from [14C]arachidonate and [3H]glucose. 5. The similar labelling ratios of fatty acid/glucose in the phospholipids of fractions D and E, and the high specific radioactivities in the total phospholipid of the soluble fraction O, suggested intrasynaptosomal phospholipid transport.

Acetylcholine↗
PubMed2000

Inhibition of Helicobacter pylori hemagglutination by polysaccharide fractions from roots of Panax ginseng.

Polysaccharides from the roots of Panax ginseng were extracted by hot water and fractionated by using ethanol precipitation and ion exchange chromatography. Fractions FC (crude extract), F1 (fraction precipitated by ethanol), F1N (fraction unbound to DEAE-Sepharose CL-6B), and F1A (bound fraction) were obtained. Their carbohydrate analyses showed that acidic fraction F1A contains higher amounts of galactose, arabinose and uronic acids, in comparison to FC and F1. Fraction F1N mainly consists of glucose. The inhibition of Helicobacter pylori-induced hemagglutination revealed different inhibitory activities of these fractions. In particular, acidic fraction F1A showed a remarkable inhibitory activity (minimum inhibition concentration was 0.25 mg/ml) among the polysacharide fractions. However, digestion of the fraction F1A with pectinase resulted in a lower molecular weight oligosaccharide fraction F1AP which was non-inhibitory at the concentration of 4 mg/ml. Comparison of inhibitory activities and carbohydrate compositions of isolated fractions indicates that the activity correlated with the contents of galactose, arabinose, and uronic acids. These data suggest that acidic polysaccharides may be responsible for the inhibitory activity.

Helicobacter pylori↗
PubMed1998

Mouse skin reactions following fractionated irradiation with carbon ions.

PURPOSE: Skin reactions in the mouse leg following various daily doses given with 290 MeV/u carbon ions were investigated. MATERIALS AND METHODS: Seven different LET (linear energy transfer) values ranging from 14 to 100keV/microm were selected. The fractionation schedules were 1-, 2-, 4- and 8-daily fractions. The isoeffect doses to produce moist desquamation on the dose-response curves were calculated with 95% confidence limits. RESULTS: The isoeffect doses for carbon ions of 14 and 20 keV/microm increased with an increase in the number of fractions up to 4 fractions, but became constant when the number of fractions further increased to 8 fractions. This leveling off in isoeffect dose was more prominent for 40 keV/microm. Recovered dose per fraction was largest for 2 fractions of the 14keV/microm carbon beam. The isoeffect doses for 50, 60, 80 and 100keV/microm consistently increased with an increase in the number of fractions and did not show saturation up to 8 fractions. RBE (relative biological effectiveness) increased linearly with LET for all fractionation schedules. CONCLUSIONS: These results suggest that daily fractionation with carbon ions could spare radiation damage in patients, and that changes the fractionation schedule affect clinical outcome.

Animals↗
PubMed1994

Identification of hepatic mitogenic and cytochrome P-450-inducing fractions of unleaded gasoline in B6C3F1 mice.

Unleaded gasoline (UG), a complex mixture of over 300 hydrocarbons, induced liver tumors selectively in female mice and exhibited liver tumor promoting activity. UG also induced cell proliferation and cytochrome P-450-related enzyme activities in mouse liver, properties commonly associated with liver tumor promoters. To determine if the mitogenic and/or cytochrome P-450-inducing properties of UG reside in individual fractions of UG, UG was separated into four fractions on the basis of boiling point (BP): fraction 1, BP < 66 degrees C; fraction 2, 66 degrees C < BP < 100 degrees C; fraction 3, 100 degrees C < BP < 132 degrees C; fraction 4, BP > 132 degrees C. Fractions 1 and 2 were combined to form "light UG" (BP < 100 degrees C), and fractions 3 and 4 were combined to form "heavy UG" (BP > 100 degrees C). Female B6C3F1 mice were implanted with osmotic pumps containing 5-bromo-2'-deoxyuridine (BrdU) on d 1, treated by intragastric intubation with corn oil or 3000 mg/kg/d of light, heavy, or whole UG on d 2-4, and euthanized on d 5. Pentoxyresorufin O-dealkylase (PROD) and ethoxyresorufin O-deethylase (EROD) activities were assayed in hepatic microsomes, and hepatocyte BrdU labeling index (LI) was determined in liver sections. Whole UG and heavy UG caused comparable increases in hepatic PROD and EROD activities and the hepatocyte LI. Light UG caused relatively small increases in hepatic PROD and EROD activities and did not increase the hepatocyte LI. When fractions 3 and 4 were tested separately in the above treatment protocol, both fractions strongly induced hepatic PROD and weakly induced hepatic EROD activities. However, only fraction 3 increased the hepatocyte LI. To isolate mitogenic components in fraction 3, equimolar doses of individual chemicals in fraction 3 were tested in the above treatment protocol. Toluene did not increase the hepatocyte LI, whereas 2,2,3-trimethylpentane (TMP), 2,2,4-TMP, and 2,3,4-TMP all dramatically increased the hepatocyte LI. Thus, while the hepatic cytochrome P-450-inducing activity of UG was concentrated in components of UG with BPs > 100 degrees C, this activity apparently resides in UG components with a wide range of BPs. The mitogenic activity of UG, in contrast, was highly concentrated in components of UG with BPs ranging from approximately 100 to 132 degrees C, and quite possibly in specific TMPs.

Animals↗
PubMed1993

Lack of agreement between measurement of ejection fraction by impedance cardiography versus radionuclide ventriculography.

OBJECTIVE: To determine the limits of agreement between left ventricular ejection fraction estimated using systolic time intervals from impedance cardiography and left ventricular ejection fraction estimated by radionuclide ventriculography. DESIGN: A prospective study for diagnostic tests using radionuclide ventriculography as the criterion standard. SETTING: A large military teaching hospital. PATIENTS: Twenty ambulatory adults scheduled for radionuclide ventriculography. MEASUREMENTS AND MAIN RESULTS: A regression equation to estimate ejection fraction from systolic time intervals is available in a widely used impedance-based cardiac monitoring device. The estimated ejection fraction is then used in an equation with stroke volume estimated by the same device to calculate an end-diastolic volume. We studied the agreement of the ejection fraction as estimated by this device with the ejection fraction estimated by radionuclide ventriculography by obtaining simultaneous estimates of ejection fraction over a broad range of adult patients. Twenty ejection fraction pairs were analyzed. The correlation of ejection fraction by impedance cardiography to ejection fraction by radionuclide ventriculography was significant (r2 = .55; p < .002). However, the mean difference between the technologies was -8.85%, with a standard deviation of the differences of 7.15%, resulting in a 95% confidence range for agreement of -23.2% to +5.5%. CONCLUSIONS: The 95% confidence range defining the limits of agreement between ejection fraction by impedance cardiography and ejection fraction by radionuclide ventriculography is not clinically acceptable. In the opinion of the authors impedance cardiography should not be used in place of radionuclide ventriculography for the assessment of ejection fraction at this time.

Adult↗
PubMed1976

Studies on the structure and function of chick-oviduct chromatin. 2. Biochemical characterization of two chromatin fractions isolated by ECTHAM-cellulose chromatography.

Chromatin prepared at various stages of hormone-mediated development of the chick oviduct was investigated for the relative proportions of transcriptionally active (fraction I) and repressed (fraction II) fractions by ECTHAM-cellulose chromatography. During primary stimulation with estrogen, the amount of chromatin DNA in fraction I plotted as a function of time of stimulation showed a bell-shaped profile, similar to the profile obtained earlier for the number of chromatin sites available to RNA polymerase for initiation of RNA synthesis. Chromatin form a transcriptionally inactive system, hen erythrocytes, eluted mainly (98%) as fraction II. The transcriptionally active fraction I of estrogen-stimulated oviduct contained a 4-fold greater RNA polymerase II activity than was found in fraction II. This could be explained by a differential inhibition of RNA polymerase activity in fraction II since enzyme preparations extracted and purified from both chromatin fractions showed equal activities. In support of this finding, fraction I eluted from ECTHAM-cellulose showed a 4-fold greater concentration of rifampicin-resistant RNA chain initiation sites as compared to fraction II. When chromatin from oviduct mince incubated with labeled progesterone and 17 beta-estradiol and was chromatographed on ECTHAM-cellulose, the transcriptionally active fraction also contained a 4-fold greater concentration of bound hormone (per weight DNA) as compared to the repressed fraction.

Animals↗
PubMed2006

Distribution of the Mycobacterium community and polycyclic aromatic hydrocarbons (PAHs) among different size fractions of a long-term PAH-contaminated soil.

Summary Mycobacterium is often isolated from polycyclic aromatic hydrocarbon (PAH)-contaminated soil as degraders of PAHs. In model systems, Mycobacterium shows attachment to the PAH substrate source, which is considered to be a particular adaptation to low bioavailability as it results into increased substrate flux to the degraders. To examine whether PAH-degrading Mycobacterium in real PAH-contaminated soils, in analogy with model systems, are preferentially associated with PAH-enriched soil particles, the distribution of PAHs, of the PAH-mineralizing capacity and of Mycobacterium over different fractions of a soil with an aged PAH contamination was investigated. The clay fraction contained the majority of the PAHs and showed immediate pyrene- and phenanthrene-mineralizing activity upon addition of (14)C-labelled pyrene or phenanthrene. In contrast, the sand and silt fractions showed a lag time of 15-26 h for phenanthrene and 3-6 days for pyrene mineralization. The maximum pyrene and phenanthrene mineralization rates of the clay fraction expressed per gram fraction were three to six times higher than those of the sand and silt fractions. Most-probable-number (MPN)-polymerase chain reaction demonstrated that Mycobacterium represented about 10% of the eubacteria in the clay fraction, while this was only about 0.1% in the sand and silt fractions, indicating accumulation of Mycobacterium in the PAH-enriched clay fraction. The Mycobacterium community composition in the clay fraction represented all dominant Mycobacterium populations of the bulk soil and included especially species related to Mycobacterium pyrenivorans, which was also recovered as one of the dominant species in the eubacterial communities of the bulk soil and the clay fraction. Moreover, Mycobacterium could be identified among the major culturable PAH-degrading populations in both the bulk soil and the clay fraction. The results demonstrate that PAH-degrading mycobacteria are mainly associated with the PAH-enriched clay fraction of the examined PAH-contaminated soil and hence, that also in the environmental setting of a PAH-contaminated soil, Mycobacterium might experience advantages connected to substrate source attachment.

Genes, Bacterial↗
PubMed1992

Utilization of fractionated soluble egg antigens reveals selectively modulated granulomatous and lymphokine responses during murine schistosomiasis mansoni.

Worm eggs deposited in the livers and intestines of Schistosoma mansoni-infected mice secrete soluble egg antigens (SEA) and induce T cell-mediated circumoval granulomas. In the present study, we fractionated crude SEA by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tested the fractions for granuloma elicitation and lymphokine production at different stages of the infection. SEA fraction-coupled beads were used to elicit artificial pulmonary granulomas. Acutely infected mice responded with granulomas to seven fractions (less than 21-, 25- to 30-, 32- to 38-, 60- to 66-, 70- to 90-, 93- to 125-, and greater than 200-kDa fractions) of SEA, whereas chronically infected mice responded to four fractions (60- to 66-, 70- to 90-, 93- to 125-, and greater than 200-kDa fractions). In response to both crude and fractionated SEA, granuloma T cells produced high levels of gamma interferon at the preacute (6-week) stage of infection, but production subsequently diminished. Interleukin-2 (IL-2) and IL-4 production peaked at the acute (8-week) stage of infection and concurrently decreased at the chronic (20-week) stage. At the acute stage of the infection, the granulomagenic SEA fractions also elicited IL-2 and IL-4 production; at the chronic stage, IL-2 production and, to a lesser degree, IL-4 production corresponded to SEA fractions that elicited granulomas. Isolated SEA proteins from the 32- to 38-kDa fraction demonstrated differential lymphokine responses: predominant gamma interferon and IL-2 production was elicited by the 32-kDa fraction, whereas the 35- and 38-kDa proteins elicited predominant gamma interferon and IL-4 production. However, all three proteins elicited granuloma formation. The present study reveals changes in granulomatous responses to SEA fractions during the acute and chronic stages of the infection as well as distinct phases of gamma interferon, IL-2, and IL-4 lymphokine production throughout the infection. Based on these results, it is concluded that granuloma formation and IL-2 and IL-4 production are interrelated.

Animals↗