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PubMed2005

Total concentrations and fractions of Cd, Cr, Pb, Cu, Ni and Zn in sewage sludge from municipal and industrial wastewater treatment plants.

Heavy metals are one of the important factors that affect the final disposal of sewage sludge. In this paper, the metal mobility and bioavailability of heavy metals in sewage sludge were studied by using Community Bureau of Reference (BCR) sequential extraction procedure to get more information for the reasonable disposal of sludge. Sewage sludge was collected from five municipal wastewater treatment plants and three industrial wastewater treatment plants. The sludge was examined for and the total concentrations and different chemical fractions of Cd, Cr, Pb, Cu, Ni and Zn. The total metal concentrations of heavy metals in sludge varied greatly. The contents of Zn and Cu were the highest, followed by then Cr, Ni and Pb and the content of Cd was the least. There was no significant difference in total metal concentration between municipal and industrial wastewater treatment plants. Fractions extracted by the BCR sequential procedure were acid soluble/exchangeable, reducible and oxidizable fraction. Sludge pH was found to have profound effect on the chemical fractions of heavy metals. Acidic sludges (Xiamen and Jinlin Petrochemical Group Co., wastewater treatment plant) had higher proportion of the acid soluble/exchangeable fractions than in neutral sludge. In neutral sludges, Pb and Cr were principally distributed in between the oxidizable fraction and the residual fraction; Cu was in the oxidizable fraction; Cd mainly in the residual fraction in municipal wastewater treatment plants and had high percentage of acid soluble/exchangeable and reducible fractions in industrial wastewater treatment plants; Ni and Zn had higher percentage in the acid soluble/exchangeable and the oxidizable fraction.

Environmental Monitoring↗
PubMed2004

Estimating vital statistics and age distributions of measurable soil organic carbon fractions based on their pathway of formation and radiocarbon content.

Radiocarbon measurements have been used in combination with "bomb 14C" models to estimate turnover of soil organic carbon fractions. However, the bomb 14C models assume that all SOC fractions are formed directly from external inputs of carbon, which is not always valid because some SOC fractions may receive carbon from other SOC fractions. Due to the continuous inputs of organic carbon, we argue that the most appropriate way to describe the age of SOC is by an age distribution. We developed age distributed models of SOC fractions and derived analytical solutions to them. The models all assume that SOC fraction decay can be described by first-order kinetics, but differ in their assumptions about the pathway of SOC fraction formation. The solutions can be used to estimate age distributions at steady state of different SOC fractions based on their radiocarbon content. These age distributions can be used to calculate the mean age, mean residence time, and other vital statistics of each measurable SOC fraction. Furthermore, if a sequential scheme is used to isolate the SOC fractions, an estimated age distribution of the total SOC can be obtained by adding the contributions of each soil fraction. The age distributions can be very helpful in interpretations of soil organic carbon dynamics in different soils.

Carbon Radioisotopes↗
PubMed1997

Usefulness of subnormal midwall fractional shortening in predicting left ventricular exercise dysfunction in asymptomatic patients with systemic hypertension.

We have recently shown that a subgroup of asymptomatic hypertensive patients exhibit subnormal left ventricular (LV) midwall fiber shortening at rest and that this finding predicts morbidity and mortality independently of age, blood pressure (BP), or the presence of LV hypertrophy. However, it is unknown whether abnormal midwall fractional shortening predicts either subnormal LV functional reserve or extracardiac damage in asymptomatic hypertensive patients. Accordingly, we compared radionuclide cineangiographic LV ejection fraction at rest and maximum exercise as well as clinical findings between 89 patients with normal and 16 patients with subnormal midwall fractional shortening by echocardiogram. Patients with low midwall fractional shortening were similar in gender, age, and systolic BP to those with normal shortening but had higher mean diastolic BP and body mass indexes (both p < 0.05). The 2 groups also had similar resting ejection fraction (56 +/- 9% vs 55 +/- 15%, with normal or subnormal shortening, respectively, p = NS). Patients with subnormal midwall fractional shortening had higher LV mass and tended to have higher urinary protein excretion and serum creatinine levels. Subnormal LV ejection fraction with exercise (< 54%) was observed in 13 of 89 patients (15%) with normal midwall fractional shortening but in 7 of 16 patients (44%) with subnormal shortening (p < 0.05). Multiple linear regression analysis revealed that midwall fractional shortening independently predicted exercise performance (p < 0.001). Thus, subnormal midwall fractional shortening predicts depressed LV fractional reserve in asymptomatic hypertensive patients and may contribute to identification of patients with extracardiac target-organ damage.

Adult↗
PubMed1995

Subpopulations of mouse resident peritoneal macrophages fractionated on Percoll gradients show differences in cell size, lectin binding and antigen expression suggestive of different stages of maturation.

Aiming the identification of macrophage heterogeneity, mouse resident peritoneal cells were fractionated on discontinuous Percoll gradients into six discrete fractions (0, 1, 2, 3, 4 and 5 in order of increasing density). All six fractions and the total population were characterized by light and electron microscopy, and flow cytometry. The least dense fraction (0) had a low viability (44%); fractions 4 and 5 had a low percentage of macrophages. Light microscopy and flow cytometry of macrophage-enriched fractions 1, 2 and 3 showed an inverse correlation between diameter and cell density, as well as suitable differences in lectin binding to the macrophages of each fraction. The surface of macrophages from fraction 1 had more sialyl residues (higher binding of the lectin LFA), less galactosyl residues (lower binding of the lectin PNA) and expressed more receptors for the antibodies M1/70 (Mac-1) and F4/80; fraction 3 had an opposite binding behavior for the lectins and expressed fewer receptors for both antibodies; fraction 2 had an intermediate behavior for both parameters. Binding of the lectins Con A and HPA showed slight differences, whereas UEA I did not present a detectable difference among the fractions analyzed. These findings suggest that the macrophage heterogeneity achieved by the gradient separation of resident peritoneal cells could be explained by different stages of macrophage maturation.

Animals↗
PubMed2001

Characterization of isolated fractions of dissolved organic matter from natural waters and a wastewater effluent.

Dissolved organic matter (DOM) was concentrated from natural waters and the effluent of a wastewater treatment plant using a portable reverse osmosis (RO) system. The humic acid (HA), fulvic acid (FA) and hydrophilic (HyI) fractions were isolated and purified by the XAD-8 resin combined with the cation exchange resin method. The FA fractions predominated in natural waters and accounted for 54-68% of the total amount of dissolved organic carbon (DOC), whereas the HA and HyI fractions constituted, respectively, 13-29 and 9-30% of the total DOC. The effluent of wastewater was almost devoid of HA and the HyI fraction exceeded FA. The elemental compositions of HA and FA were in the ranges typical for natural humic materials, but the HyI fractions did not exhibit humic character. 1H NMR spectra revealed that the HyI fractions were almost devoid of aromatic protons and the aliphatic region featured more sharp signals than HA and FA fractions, indicating that HyI fractions were consisted of more simple compounds and less complex mixtures. The aliphatic functional groups in these fractions of DOM samples followed the order HA < FA HyI. The rate of Cu complexation with the HyI fraction was faster than the rate with the HA or FA fraction of the Suwannee River DOM, implying that copper reacted with relatively weak ligands faster than with strong ligands.

Benzopyrans↗
PubMed2003

Microbial in situ degradation of aromatic hydrocarbons in a contaminated aquifer monitored by carbon isotope fractionation.

We present an approach for characterizing in situ microbial degradation using the 13C/12C isotope fractionation of contaminants as an indicator of biodegradation. The 13C/12C isotope fractionation of aromatic hydrocarbons was studied in anoxic laboratory soil percolation columns with toluene or o-xylene as the sole carbon and electron source, and sulfate as electron acceptor. After approximately 2 months' of incubation, the soil microbial community degraded 32 mg toluene l(-1) and 44 mg o-xylene l(-1) to less than 0.05 mg l(-1), generating a stable concentration gradient in the column. The 13C/12C isotope ratio in the residual non-degraded fraction of toluene and o-xylene increased significantly, corresponding to isotope fractionation factors (alphaC) of 1.0015 and 1.0011, respectively. When the extent of biodegradation in the soil column was calculated based on the measured isotope ratios (R(t)) and an isotope fractionation factor (alphaC=1.0017) obtained from a sulfate-reducing batch culture the theoretical residual substrate concentrations (C(t)) matched the measured toluene concentrations in the column. This indicated that a calculation of biodegradation based on isotope fractionation could work in systems like soil columns. In a field study, a polluted, anoxic aquifer was analyzed for BTEX and PAH contaminants. These compounds were found to exhibit a significant concentration gradient along an 800-m groundwater flow path downstream of the source of contamination. A distinct increase in the carbon isotope ratio (delta13C) was observed for the residual non-degraded toluene (7.2 per thousand ), o-xylene (8.1 per thousand ) and naphthalene fractions (1.2 per thousand ). Based on the isotope values and the laboratory-derived isotope fractionation factors for toluene and o-xylene, the extent to which the residual substrate fraction in the monitoring wells had been degraded by microorganisms was calculated. The results revealed significant biodegradation along the groundwater flow path. In the wells at the end of the plume, the bioavailable toluene and o-xylene fractions had been almost completely reduced by in situ microbial degradation. Although indane and indene showed decreasing concentrations downstream of the groundwater flow path, suggesting microbial degradation, their carbon isotope ratios remained constant. As the physical properties of these compounds are similar to those of BTEX compounds, the constant isotope values of indane and indene indicated that microbial degradation did not lead to isotope fractionation of all aromatic hydrocarbons. In addition, physical interaction with the aquifer material during the groundwater passage did not significantly alter the carbon isotope composition of aromatic hydrocarbons.

Biodegradation, Environmental↗
PubMed1997

Skin carcinogenicity of condensed asphalt roofing fumes and their fractions following dermal application to mice.

Condensed roofing asphalt fumes, generated at 316 degrees C, were collected by cold trap condensation and fractionated by preparative high performance liquid chromatography. Chemical classes in each of the fractions (A-E) were identified by gas chromatography/mass spectroscopy. The fractions, various combinations of fractions, the raw and heated asphalt, the neat asphalt fume and the reconstituted asphalt were tested for carcinogenicity, and three fractions were tested for cocarcinogenicity and tumor promotion with benzo[a]pyrene (BaP). The skin application carcinogenesis bioassay was conducted by twice weekly application of test materials in 0.05 ml of acetone/cyclohexane (1:1) for 104 weeks to 40 groups of male C3H/HeJ mice (30/group). Fractions were applied at a mass in proportion to their amount in the neat asphalt fumes. In addition, the neat asphalt fume was tested on Sencar mice to determine if this strain was more susceptible to the carcinogenic effects of the fumes. Condensed neat asphalt fumes produced similar and statistically significant increased tumor yields of papillomas and carcinomas in both strains as compared to respective vehicle controls. Recombination of all fractions resulted in a tumor response similar to neat asphalt fumes. Among individual fractions, C was most potent, followed by B. The other single fractions were without significant tumorigenic activity. Combinations containing fractions B and C were most active among the mixtures that were assayed and no evidence of enhancement of tumorigenesis in the mixtures was found. No significant cocarcinogenic or tumor promoting activity was observed with fractions A, D, or E and BaP. Raw unheated asphalt produced a few tumors in C3H mice, but no tumors were seen when raw asphalt heated to 316 degrees C, with the fumes permitted to escape, was applied.

Animals↗
PubMed2003

The linear-quadratic model and fractionated stereotactic radiotherapy.

PURPOSE: To determine the dose per fraction that could be used when gamma knife or linear accelerator-based stereotactic treatments are delivered in 2 or more fractions. METHODS AND MATERIALS: The linear-quadratic (LQ) model was used to calculate the dose per fraction for a multiple-fraction regimen which is biologically equivalent to a given single-fraction treatment. The results are summarized in lookup tables. RESULTS AND CONCLUSION: The tables can be used by practicing clinicians as a guide in planning fractionated treatment. For the large doses used in typical stereotactic treatments and for small fraction numbers, the model is not very sensitive to the value of the alpha/beta ratio in the LQ model. A simple rule of thumb is found that for two-fraction and three-fraction treatments the dose per fraction is roughly two-thirds and one-half of the single-fraction treatment dose, respectively.

Linear Models↗
PubMed1993

Audit reduces the reluctance to use single fractions for painful bone metastases.

We have conducted three audits of the number of fractions used within our department to treat symptomatic bone metastases. The initial audit identified 133 patients treated for bone metastases in a 3-month period using 538 fractions (mean number of fraction = 4.1, range 1-14). These figures were presented at our audit meeting along with a literature review which provided no evidence of any advantage of multiple fractions over single fractions. Departmental guidelines recommending the use of single fractions were established. A subsequent audit identified 149 patients treated with 520 fractions (mean number of fractions = 3.5, range 1-11). A third audit identified 148 patients treated with 335 fractions (mean number of fractions = 2.3, range 1-10). Audit has resulted in a reduction in the number of fractions used to treat bone metastases in our department. The major effect was seen after the second audit.

Bone Neoplasms↗
PubMed1985

Interaction of Cibacron Blue F3GA with glutamine synthetase: use of the dye as a conformational probe. 2. Studies using isolated dye fractions.

By means of column chromatography on silicic acid, commercial preparations of Cibacron Blue F3GA have been resolved into four major subfractions (fractions I-IV). The difference spectrum between free dye and dye bound to any given form of Escherichia coli glutamine synthetase (GS) is different for each dye fraction. Moreover, uniquely different spectral perturbations are associated with the binding of any one dye fraction to the taut, relaxed, dissociated, or oxidized forms of GS. On the basis of the magnitude of the differences in the difference spectra between free dye and the dye-GS complexes, fraction II is most suitable for monitoring the interconversion of the relaxed and taut forms of GS. Fraction II can also be used to measure the fraction of oxidized (inactive) GS that is present in apparently homogeneous GS preparations. In contrast to the other three fractions, the difference spectrum obtained immediately following the binding of fraction I to GS undergoes a time-dependent change which is associated with the covalent attachment of the dye to the enzymes. Fractions II, III, and IV apparently bind to the nucleotide binding site on GS because the difference spectrum obtained with these fractions can be quenched by the subsequent addition of 1-2 mM ADP. The primary but not the secondary complex formed between GS and fraction I can also be destroyed by ADP.

Coloring Agents↗
PubMed2002

Early decline in left ventricular ejection fraction predicts doxorubicin cardiotoxicity in lymphoma patients.

Thirty adult patients with non-Hodgkin's lymphoma were studied to evaluate prospectively the significance of early decline in left ventricular ejection fraction after low cumulative doxorubicin dose (200 mg x m(-2)) in predicting the later impairment of left ventricular function. Cardiac function was monitored with radionuclide ventriculography at baseline and after cumulative doxorubicin doses of 200, 400 and 500 mg x m(-2). Cardiotoxicity was defined as a decrease in left ventricular ejection fraction of more than 10% units to a final left ventricular ejection fraction < or =50%. Twenty-eight patients received doxorubicin > or =400 mg x m(-2) and were evaluable for cardiotoxicity. Clinical heart failure developed in two patients (7%) after a cumulative doxorubicin dose of 500 mg m(-2). Left ventricular ejection fraction decreased more than 10% absolute ejection fraction units to a final left ventricular ejection fraction < or =50% in 10 patients (36%). Left ventricular ejection fraction decreased from 56+/-1.5% to 53.6+/-1.5% (P=0.016) in patients with no cardiotoxicity, and from 60.8+/-2.4% to 41.8+/-2.0% (P<0.001) in patients with cardiotoxicity. For patients who developed cardiotoxicity, the fall in left ventricular ejection fraction after a cumulative doxorubicin dose of only 200 mg x m(-2) was highly significant (left ventricular ejection fraction 49.7+/-1.8%, P=0.001 vs baseline). In receiver operator characteristic analysis, the area under the curve for the decrease in left ventricular ejection fraction at a cumulative doxorubicin dose of 200 mg x m(-2) for predicting cardiotoxicity in all patients was 0.858. The decrease in left ventricular ejection fraction of more than 4% units after a cumulative doxorubicin dose of 200 mg x m(-2) had a 90% sensitivity and 72% specificity for predicting later cardiotoxicity. Our results show that the significant impairment of left ventricular function during doxorubicin therapy can be predicted early, already at low cumulative doxorubicin doses. This finding may be of value in identifying patients at high or low risk for the development of anthracycline cardiotoxicity.

Adult↗
PubMed1981

Binding to antithrombin of heparin fractions with different molecular weights.

The interaction between bovine antithrombin, a plasma proteinase inhibitor, and heparin species of different molecular weights was studied. A commercial heparin preparation was divided by gel chromatography into a number of fractions with average molecular weights ranging from 6000 to 34700. Each of these fractions was further fractionated by affinity chromatography on matrix-bound antithrombin. In the latter procedure, those heparin fractions that had molecular weights lower than about 14000 were separated into three peaks. The material in the first of these was not adsorbed on the column, and the other two peaks corresponded to the low-affinity and high-affinity peaks described previously. In contrast, high-molecular-weight heparin samples gave only the low-affinity and high-affinity fractions. U.v. difference absorption studies showed that the non-adsorbed heparin fraction bound to antithrombin in solution with a binding constant at physiological ionic strength only slightly lower than that of low-affinity heparin. The division between the two fractions thus is arbitrary and only dependent on the conditions selected for the affinity-chromatography experiment. Stoicheiometries and binding constants for the binding of several high-affinity heparin species to antithrombin were determined by fluorescence titrations. High-affinity heparin fractions of equal elution positions in the beginning of the peaks of the affinity chromatographies, but with different molecular weights, showed stoicheiometries that were not experimentally distinguishable from 1:1 and also had no appreciable differences in binding constants. However, the anticoagulant activities, calculated on a molar basis, of these fractions increased markedly with molecular weight, a behaviour that thus cannot be explained by differences in the binding of the fractions to antithrombin. In contrast, high-affinity samples of similar molecular weights, which were eluted at increasing ionic strengths from matrix-linked antithrombin, were found to have an increasing proportion of chains with two binding sites for antithrombin and also to have progressively higher binding constants. These binding properties at least partly explain the increasing anticoagulant activities that were observed for these fractions.

Antithrombins↗
PubMed1981

The identification of polynuclear aromatic hydrocarbon (PAH) derivatives in mutagenic fractions of diesel particulate extracts.

The soluble organic fraction (SOF) of particulate matter from diesel exhaust (from point sources, ambient air, etc.) contains hundreds of organic constituents. Norman-phase high pressure liquid chromatography (HPLC) has been used to separate the SOF into subfractions suitable for subsequent chemical analysis and bioassays. These fractions consist of non-polar(PAH), moderately polar (transition) and highly polar constituents. The non-polar fractions have been well characterized and consist of PAH and aliphatic hydrocarbons. The specific compounds present in the transition and polar fractions are for the most part unknown. This analytical information has been difficult to obtain since these compounds are highly labile, polar, of low volatility and in very low concentrations when compared to the bulk of material found in the SOF. Mutagenicity tests using the Ames Salmonella typhimurium assay indicate that the transition fraction accounts for most of the mutagenicity when compared to the non-polar (PAH) and polar fractions. A variety of chromatographic and mass spectrometric techniques are described that have been used to determine the composition of the HPLC fractions. More than one hundred species have been identified in the transition fraction of diesel particulate matter using high resolution gas chromatography (HRGC)/high resolution mass spectrometry (HRMS), HPLC and direct-probe high resolution mass spectrometry. It has been found that the transition fraction contains mostly PAH derivatives consisting of hydroxy, ketone, quinone, carboxaldehyde, acid anhydride and dihydroxy derivatives of PAH. Three nitro-PAH species have been tentatively identified and 1-nitropyrene positively identified in the transition fraction. The 1-nitropyrene was found to account for approximately 45% and 30% of the direct-acting mutagenicity observed for the transition fraction and total extract, respectively. The HPLC separation procedure was shown to give better than 95% recovery of the mass and mutagenic activity. The problem of PAH oxidation during the analytical procedures and possible effect on bioassay results are discussed.

Dose-Response Relationship, Drug↗
PubMed1999

Metals associated with both the water-soluble and insoluble fractions of an ambient air pollution particle catalyze an oxidative stress.

One potential mechanism of injury mediated by air pollution particles is through metal-catalyzed oxidant generation. In one emission source particle, soluble metals have been associated with biological effect and toxicity. However, a majority of metals in ambient air pollution particles can be associated with insoluble components. We tested the hypothesis that concentrations of catalytically active metal in ambient air pollution particles are not equivalent to the concentrations of water-soluble metal. Twelve filters collected from the North Provo, UT, monitoring station were agitated in deionized water. Both the aqueous extract and pellet were isolated, lyophilized, and defined as the water-soluble and insoluble fractions, respectively. The fractions were chemically characterized and ionizable concentrations of metals were measured using inductively coupled plasma emission spectroscopy. While the water-soluble fraction had significantly greater concentrations of ionizable metals per unit mass, the insoluble fraction also had measurable quantities. In vitro oxidant generation by the two fractions, measured as thiobarbituric acid-reactive-products of deoxyribose, corresponded to the concentrations of ionizable rather than total metals. The release of interleukin-8 by cultured respiratory epithelial cells after incubation with the two fractions also coincided with the ionizable metal concentrations. Finally, neutrophil influx and lavage protein levels 24 h after instillation of the two fractions in rats reflected the ionizable metal concentrations, in vitro oxidative stress, and mediator release. We conclude that catalytically active metals can be measured in both the soluble and insoluble fractions of an ambient air pollution particle. These metals corresponded to the biological activity of the two fractions. While in greater concentration in the water-soluble fraction, larger total quantities of catalytically and biologically active metals are likely to be associated with the insoluble fraction as a result of the abundance of the latter.

Air Pollutants↗
PubMed1988

Repair kinetics in mouse lung after multiple X-ray fractions per day.

The potential advantage for sparing normal tissue damage by hyperfractionation of low-LET radiation may be limited by the repair kinetics of tissues in the irradiated field. Tissues with slow repair kinetics will limit the number of fractions that may be given on the same day. Results are presented for mouse lung treated with a range of doses per fraction using either two or three fractions per day in multiple X-ray fractionation schedules. The results are analysed to determine whether the repair kinetics follow a single exponential function of time. The calculated repair rate (T1/2) was about 1.2 h for two fractions per day of 2 Gy (10F/5d) but slightly less (T1/2 = 0.8 h) for two fractions of 9 Gy (2F/1d). For smaller doses per fraction of 1.1 Gy, given three times per day (39F/13d), the T1/2 was not significantly less (T1/2 = 0.3-0.7 h). For three fractions per day of 1.1 Gy per fraction an unsatisfactory fit is achieved using a single exponential function of time, and a better fit is obtained using two components of repair. The repair kinetics are slow for lung, in comparison to acute reacting tissues (except skin), and may require that 6-8 h (i.e. four or five half-times) should be allowed between fractions on the same day so that more than 95 per cent of the repairable dose is repaired. At present the variation in repair kinetics with doses per fraction between 1.1 and 9 Gy are not significantly different, so no reduction of interfraction interval should be proposed.

Animals↗
PubMed1980

Excretion and storage of [14C]toxaphene and two isolated [14C]toxaphene fractions.

The 7-d urinary and fecal excretions of [14C]toxaphene and two isolated [14C]toxaphene fractions (polar fraction 7 and nonpolar fraction 2) were determined in orally dosed rats. The urinary, fecal, and total excretions of toxaphene were, respectively, 22.5, 35.7, and 58.2% of the administered dose. The total excretions of fractions 2 and 7 were, respectively, 69.4 and 65.0%, and the overall order of excretion was fraction 2 greater than toxaphene greater than fraction 7. All three groups had low toxaphene levels (below 0.2 ppm) in all tissues analyzed except for fat, where significant levels were detected. Hexane and chloroform extracts of the urine revealed that the activity was more polar than the parent material for all three groups. Apparently, toxaphene must be metabolized before it can be excreted in the urine. When fat extracts were analyzed by thin-layer chromatography and autoradiography, differences were found between the parent material and the extracted activity. There was an increase in polar activity in the residue obtained from toxaphene-treated rats. The fat from the fraction 2 group contained fraction 2 and two additional more polar spots, which represented about 11% of the total activity. The fat from the fraction 7 group also contained two additional spots, but they were less polar than fraction 7. Apparently, the metabolism of fraction 7 results in some products that are less polar and, perhaps, more persistent.

Adipose Tissue↗
PubMedDate not supplied

Mutagenicity and chemical analysis of aliphatic and aromatic fractions of Prudhoe Bay crude oil and fuel oil no. 2.

The mutagenicity of aliphatic (fraction 1), one- to three-ring aromatic (fraction 3), and four- to five-ring aromatic (fraction 4) fractions of Prudhoe Bay crude oil and of a fuel oil no. 2 was investigated with a battery of in vitro mammalian and microbial assays. Chemical analysis of the fractions was carried out by gas capillary chromatography-mass spectrometry. In the Salmonella/mammalian microsome test, both first fractions were negative, while fraction 3 of Prudhoe Bay crude and fraction 4 of both oils exhibited mutagenic activity with metabolic activation. In Chinese hamster ovary cells, all of the aromatic fractions, in the presence of metabolic activation, caused a significant increase in the number of sister chromatid exchanges. Chromosome aberrations were not caused by any of the aromatic fractions; however, fraction 3 of fuel oil no. 2 induced endoreduplication in the presence of metabolic activation.

Animals↗
PubMed1958

A cytochemical study on the pancreas of the guinea pig. I. Isolation and enzymatic activities of cell fractions.

Pancreatic tissue, (guinea pig) homogenized in 0.88 M sucrose, was fractionated by differential centrifugation into a nuclear, zymogen, mitochondrial, microsomal, and final supernatant fraction. The components of the particulate fractions were identified with well known intracellular structures by electron microscopy. The fractions were analyzed for protein-N and RNA, and were assayed for RNase and trypsin-activatable proteolytic (TAPase) activity. The zymogen fraction accounted for 30 to 40 per cent of the total TAPase and RNase activities, and its specific enzymatic activities were 4 to 10 times higher than those of any other cell fraction. The zymogen fraction was cytologically heterogeneous; zymogen granules and mitochondria represented its main components. More homogeneous zymogen fractions, obtained by successive washing or by separation in a discontinuous density-gradient, had specific activities 2 to 4 times greater than the crude zymogen fractions. Chymotrypsinogen was isolated by column chromatography from pancreas homogenates and derived cell fractions. The largest amount was recovered in the zymogen fraction. The final supernatant had properties similar to those of the trypsin inhibitor described by Kunitz and Northrop.

Chymotrypsinogen↗