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PubMed1995

Characterization of partially purified alpha-glucosidase in the insoluble fraction of bovine crystalline lens.

Two fractions of neutral alpha-glucosidase were partially purified from the insoluble fraction of bovine lens. This is the first report of such an event to the best of our knowledge. The apparent native molecular weights of these fractions were 121 kDa (fraction-I) and 254 kDa (fraction-II). Both fractions contained three polypeptides with molecular weights of 21, 25 and 30 kDa, although the proportion of these peptides was different in both fractions. The optimal pH of fraction-I and fraction-II was pH 6.0 and 6.5, and the optimal temperature for both fractions was approximately 50 degrees C. The Km values of fractions-I and -II for 4-methylumbelliferyl-alpha-glucopyranoside were 0.086, and 0.192 mM. The activities of these enzymes were inhibited strongly by HgCl2 and slightly by D-iodoacetic acid, but not by D-turanose. From this, we suggest that the enzyme in the insoluble fraction of bovine lens may be a cytoplasmic neutral alpha-glucosidase which binds to the cell membrane.

Animals↗
PubMed1983

Disposition of fractionated 3H-heparin in rats.

To evaluate the disposition of fractionated 3H-heparin, high affinity fraction (fraction A) and low affinity fraction (fraction NA) to protamine were prepared in this study from commercial 3H-heparin by affinity chromatography on protamine-Sepharose and gel filtration chromatography. Following intravenous administration of fraction A to rats, it seemed that the radioactivity in plasma declined one-exponentially with time to a pseudo-steady-state level, and 20.5% of dose was excreted in urine in 5 h. However, following the administration of fraction NA to rats, the plasma radioactivity curve was different from that of fraction A, and 69.8% of dose was excreted in urine in 5 h. It was found that fraction A and fraction NA had the distinctly different disposition characteristics in the body. Additionally, whole-body autoradiography with fraction A showed that the liver, bone marrow, kidney cortex, salivary gland and intestine played an important role in the distribution of it. It was suggested by gel filtration chromatography and affinity chromatography that the main material of the radioactivity excreted in urine in 5 h has the same properties as that of the administered heparin fraction.

Animals↗
PubMed2004

Evaluation of the colchicine-like activity of Gloriosa superba-extracted fractions for mosquito (Diptera: Culicidae) cytogenetic study.

Four fractions of Gloriosa superba L., i.e., hexane fraction, dichloromethane fraction 1, dichloromethane fraction 2, and methanol fraction, were investigated for colchicine-like activity using a mosquito cytogenetic assay. The results revealed that the latter three fractions yielded promisingly high colchicine-like activity, whereas the hexane fraction yielded very low activity compared with 1% colchicine in a 0.85% sodium chloride solution. The metaphase rates and average number of metaphase chromosomes per positive brain ganglion (range) of Aedes aegypti L. larvae after incubation with 0.25-2% solutions of dichloromethane fraction 1, dichloromethane fraction 2, 0.5-2% solutions of methanol fraction, and 1% colchicine solution were 90-100% and 7 (2-19) to 22 (7-47); 90-100% and 4 (1-11) to 30 (4-73); 95-100% and 11 (1-28) to 17 (2-62); and 100% and 6 (2-11), respectively. The temperature stability tests of the three promising fractions were performed by heating 0.5% working solution at 121 degrees C for 15 min and preparing 0.5% working solution from stock frozen at -20 degrees C for 10 mo. These fractions also yielded satisfactory outcomes of metaphase rates and an average number of metaphase chromosomes per positive brain ganglia compared with 1% colchicine solution.

Animals↗
PubMed2004

Fractional calculus in bioengineering, part 3.

Fractional calculus (integral and differential operations of noninteger order) is not often used to model biological systems. Although the basic mathematical ideas were developed long ago by the mathematicians Leibniz (1695), Liouville (1834), Riemann (1892), and others and brought to the attention of the engineering world by Oliver Heaviside in the 1890s, it was not until 1974 that the first book on the topic was published by Oldham and Spanier. Recent monographs and symposia proceedings have highlighted the application of fractional calculus in physics, continuum mechanics, signal processing, and electromagnetics, but with few examples of applications in bioengineering. This is surprising because the methods of fractional calculus, when defined as a Laplace or Fourier convolution product, are suitable for solving many problems in biomedical research. For example, early studies by Cole (1933) and Hodgkin (1946) of the electrical properties of nerve cell membranes and the propagation of electrical signals are well characterized by differential equations of fractional order. The solution involves a generalization of the exponential function to the Mittag-Leffler function, which provides a better fit to the observed cell membrane data. A parallel application of fractional derivatives to viscoelastic materials establishes, in a natural way, hereditary integrals and the power law (Nutting/Scott Blair) stress-strain relationship for modeling biomaterials. In this review, I will introduce the idea of fractional operations by following the original approach of Heaviside, demonstrate the basic operations of fractional calculus on well-behaved functions (step, ramp, pulse, sinusoid) of engineering interest, and give specific examples from electrochemistry, physics, bioengineering, and biophysics. The fractional derivative accurately describes natural phenomena that occur in such common engineering problems as heat transfer, electrode/electrolyte behavior, and sub-threshold nerve propagation. By expanding the range of mathematical operations to include fractional calculus, we can develop new and potentially useful functional relationships for modeling complex biological systems in a direct and rigorous manner. In Part 2 of this review (Crit Rev Biomed Eng 2004; 32(1):105-193), fractional calculus was applied to problems in nerve stimulation, dielectric relaxation, and viscoelastic materials by extending the governing differential equations to include fractional order terms. In this third and final installment, we consider distributed systems that represent shear stress in fluids, heat transfer in uniform one-dimensional media, and subthreshold nerve depolarization. Classic electrochemical analysis and impedance spectroscopy are also reviewed from the perspective of fractional calculus, and selected examples from recent studies in neuroscience, bioelectricity, and tissue biomechanics are analyzed to illustrate the vitality of the field.

Axons↗
PubMed1996

Middle-sized molecule fractions isolated from uremic ultrafiltrate and normal urine inhibit ingestive behavior in the rat.

Uremic patients with suppressed food intake may regain appetite soon after starting dialysis, presumably because of the removal of one or more toxic factors that suppress appetite. To investigate this matter, this study used a new experimental model in free-moving, unstressed male Wistar rats (300 to 350 g) with feeding catheters channeled from the top of the skull to the oral cavity. When the rats recovered from surgery, they were tested under standardized conditions by being given an intraoral infusion (1 mL/min) of a 1 M sucrose solution or a 97 g/L protein solution or a mixed solution of carbohydrate, protein, and fat (Fortimel (Nutricia Nordica AB, Stockholm, Sweden)) while the time (volume) of ingestion was recorded. Solutions to be tested for their ability to inhibit ingestion were injected intraperitoneally (lp) and the intraoral infusion was started 20 min later. Plasma ultrafiltrate was collected from end-stage renal failure patients by isolated ultrafiltration at the beginning of their first hemodialysis and pooled. Ultrafiltrate was also obtained by filtering pooled plasma from healthy volunteers in vitro, using the same type of dialyzer and cellulose acetate membranes as those used in the uremic patients. Morning urine samples from healthy volunteers were pooled and subjected to the same in vitro filtration procedure as the normal plasma. Intraperitoneal injection of 20 mL normal ultrafiltrate had no effect on sucrose ingestion, whereas injection of 20 mL uremic ultrafiltrate reduced the ingestion of sucrose solution by 23% and the ingestion of Fortimel by 17%. Ten mL of ultrafiltrate from normal urine reduced the sucrose intake by 42%. The pooled ultrafiltrates from normal and uremic plasma and normal urine were subjected to molecular filtrations using a series of membranes with known cut-off points. The filtrations yielded four concentrated fractions with molecular weight ranges of 0.1 to 0.5 kilodaltons (kd), 0.5 to 1 kd, 1 to 5 kd, and 5 to 10 kd, respectively; the plasma fractions were concentrated a factor of about 25:1 and the urine fractions by about 15:1. After an ip injection of 2 mL of each concentrated plasma fraction, only the 1 to 5 kd fraction from the uremic ultrafiltrate inhibited sucrose intake, whereas the corresponding fraction from the normal ultrafiltrate had no effect. After injection of 1, 3, and 5 mL of the concentrated fractions of uremic ultrafiltrate, a dose-dependent inhibition of sucrose intake was achieved with the 1 to 5 kd fraction and, to a lesser extent, with the 5 to 10 kd fraction. Intraperitoneal injection of 0.5, 1.0, and 2 mL of the concentrated 1 to 5 kd fraction, but not of the other fractions from normal urine, also resulted in a dose-dependent inhibition of sucrose intake. The 1 to 5 kd fractions from the uremic ultrafiltrate and the normal urine ultrafiltrate also inhibited protein intake in a dose-dependent manner. These results suggest that one or more toxic compounds in the middle-molecule weight range, which are normally excreted in the urine, accumulate in uremia and suppress food intake.

Animals↗
PubMed1994

Ruminal digestion and glycosyl linkage patterns of cell wall components from leaf and stem fractions of alfalfa, orchardgrass, and wheat straw.

Samples of alfalfa, orchardgrass, and wheat straw were hand-separated into leaf and stem fractions that were subjected to in situ ruminal fermentation for various lengths of time to assess the rate and extent of degradation of cell wall neutral monosaccharides, uronic acids, acetyl groups, and hydroxycinnamic acids. A second objective was to measure the glycosyl linkage patterns of leaf and stem fractions of substrates before and after ruminal fermentation. Samples were fermented for 0, 6, 12, 24, 48, 96, and 192 h in each of two ruminally cannulated steers. In situ disappearance data were fitted to a first-order exponential equation to estimate the following substrate parameters: insoluble, potentially digestible fraction (fd), indigestible fraction (fi), and fractional rate constant of degradation of the potentially digestible fraction (k). Leaves contained larger concentrations of crude protein and smaller concentrations of cell wall components than did stem fractions. Estimates of fi were 7.3, 39.2, 22.1, 49.3, 27.7, and 36.3 for dry matter disappearances for alfalfa leaf, alfalfa stem, orchardgrass leaf, orchardgrass stem, wheat straw leaf, and wheat straw stem, respectively. Averaged across substrates, estimates of fi for arabinose, galactose, glucose, xylose, uronic acids, acetyl groups, and p-coumaric acid were 16.5, 11.4, 14.8, 31.2, 12.8, 25.3, and 22.6% in leaf fractions and 29.5, 19.9, 37.5, 56.2, 35.0, 52.4, and 44.6% in stem fractions. Rates of digestion of all monomeric components except galactose and xylose were greater (P < .05) for alfalfa than for orchardgrass or wheat straw. Differences in digestibility of cell wall components from leaf and stem fractions were greater in alfalfa and orchardgrass than in wheat straw. Glycosyl linkage analysis indicated that xylans in leaf and stem fractions of alfalfa, orchardgrass leaf, and wheat straw stem that resisted degradation had a lower degree of substitution with acid-labile constituents (i.e., other monosaccharides) than was found in original substrates. Different rates and extents of digestion of leaf and stem fractions of forages explain part, but not all, of the observed differences in digestibilities of cell wall monomers by ruminants.

Animals↗
PubMed2006

Importance of the sampled milk fraction for the prediction of total quarter somatic cell count.

This study investigated the changes in somatic cell counts (SCC) in different fractions of milk, with special emphasis on the foremilk and cisternal milk fractions. Therefore, in Experiment 1, quarter milk samples were defined as strict foremilk (F), cisternal milk (C), first 400 g of alveolar milk (A1), and the remaining alveolar milk (A2). Experiment 2 included 6 foremilk fractions (F1 to F6), consisting of one hand-stripped milk jet each, and the remaining cisternal milk plus the entire alveolar milk (RM). In Experiment 1, changes during milking indicated the importance of the sampled milk fraction for measuring SCC because the decrease in the first 3 fractions (F, C, and A1) was enormous in milk with high total quarter SCC. The decline in SCC from F to C was 50% and was 80% from C to A1. Total quarter SCC presented a value of approximately 20% of SCC in F or 35% of SCC in C. Changes in milk with low or very low SCC were marginal during milking. Fractions F and C showed significant differences in SCC among different total SCC concentrations. These differences disappeared with the alveolar fractions A1 and A2. In Experiment 2, a more detailed investigation of foremilk fractions supported the findings of Experiment 1. A significant decline in the foremilk fractions even of F1 to F6 was observed in high-SCC milk at concentrations >350 x 10(3) cells/mL. Although one of these foremilk fractions presented only 0.1 to 0.2% of the total milk, the SCC was 2- to 3-fold greater than the total quarter milk SCC. Because the trait of interest (SCC) was measured directly by using the DeLaval cell counter (DCC), the quality of measurement was tested. Statistically interesting factors (repeatability, recovery rate, and potential matrix effects of milk) proved that the DCC is a useful tool for identifying the SCC of milk samples, and thus of grading udder health status. Generally, the DCC provides reliable results, but one must consider that SCC even in strict foremilk can differ dramatically from SCC in the total cisternal fraction, and thus also from SCC in the alveolar fraction.

Animals↗
PubMed1989

Fractionated sera from Schistosoma mansoni infected patients confers passive protection in mice.

Sera from humans with chronic Schistosoma mansoni infections (CHS) were chromatographed with CNBr-activated Sepharose 4 B conjugated with NP-40 extracts obtained from live 3 hr schistosomula. Both unbound (CHSUB) and bound (CHSB) fractions which contained IgG and IgM isotypes were characterized by ELISA, immunofluorescence, and complement-mediated in vitro killing assays. ELISA data showed that the CHSB fraction recognized schistosomula NP-40 extracts, whereas the CHSUB fraction did not. However, both CHSUB and CHSB fractions recognized 8 M urea adult worm extracts and 8 M urea egg extracts. By indirect immunofluorescence assay, the CHSB fraction recognized epitopes on the surface of live schistosomula 3 hr-29 days of age, whereas the CHSUB fraction showed surface fluorescence only on 24- and 29-day-old worms. The CHSB fraction mediated 95% killing of schistosomula in a complement dependent in vitro assay, the CHSUB fraction and the unfractionated CHS did not exhibit killing ability. The CHSUB fraction was able to titrate out the killing ability of the CHSB fraction in in vitro cytotoxic assays when mixed with the CHSB fraction at increasing concentrations. In passive immunization experiments, the CHSB fraction provided approximately 30% passive protection in mice when injected 1 day or 6 days after challenge and 20% protection when injected at 15 days, but failed to provide protection when administered greater than or equal to 24 days after challenge. Unfractionated CHS failed to mediate passive protection.

Animals↗
PubMed2002

[Proteomic analysis of different fractions in M. tuberculosis culture].

To provide a basis of molecular genetic analysis of M. tubereulosis, the proteomic profiling was prompted. M. tuberculosis H37RV was cultured in Sauton medium at 37 degrees C for 3 weeks, harvested and fractionated into three portions: suspension filtration proteins(A), cytosol proteins(B) and membrane proteins(C). These fractions were analyzed by pH3-10 IPG gradient and SDS-PAGE. The silver-stained technigue and gel images were used. Then the image was transfered into 2-DE gel analysis Software. A part of protein sports of expression level higher from the culture filtrate fraction were identified by peptide mass fingerprinting. A total of 907, 884 and 681 protein sports were observed for A. B. C fractions in M. tuberculosis H37RV, respectively. Distribution of proteins mass for 3 fractions were principally similar, About 70.5-74.4 per cent were distributed in the ranges of Mr 10-49 kD.pI of the proteins for A, B fractions were pricipally similar, About 80.9-83.5 per cent were distributed in the ranges of pH 3.0-6.4, But the number of protein sports for C fraction distributed in the ranges of pH 7.6-10.0 were more than A, B fractions. The number of protein sports of expression level higher for A, B and C fractions were 71(7.8%), 242(27.4%), 19 (2.8%), respectively. 90 pen cent from them, pH of the proteins were distributed in the ranges of pH 3.0-6.4. 73.1 per cent for proteins mass of C fraction were distributed in the ranges of 10 kD-49 kD, which were more than A, B fractions. Nine of the proteins identified ih this study appeared to be homology or putative fanction proteins, but another five proteins were unknown. The proteomic profiling of different fractions in M. tuberculosis obtained in here will be provide a basis for detailed analysis of biology functions of the proteins.

Bacterial Proteins↗
PubMed1992

A test of equal effect per fraction in the kidney of the mouse.

Measurements of renal damage in the mouse were made to determine if there was an equal effect per fraction during a course of repeated 240-kVp X-ray doses. An X-ray dose of 2 Gy was given 2, 8, 14, or 20 times with interfraction intervals of 12 h. Some animals were also irradiated with twenty 2-Gy doses using a 5-h interfraction interval. The underlying effect per fraction (-logeSF of the notional target cell population) was determined from the additional top-up dose of d(4)-Be neutrons needed to produce measurable renal impairment assessed by decreased clearance from the plasma of [51Cr]EDTA and by a reduction in the hematocrit at 25, 29, 33, and 39 weeks after treatment. There was no significant influence of the time of assay on the values of underlying effect measured. A mean value of underlying effect was therefore calculated for the two different assays of each mouse, from the measurements at the four times. This gave approximately 40 estimates (one for each animal assessed) with each assay of the effectiveness of 2-Gy fractions in each of the four fractionation schedules, a total of 321 determinations in the study with 12-h intervals. Regression analysis showed that there was no significant trend in underlying effect per fraction with number of fractions, i.e., the damage per fraction was constant regardless of the number of fractions used. With underlying effect normalized to 1 unit of damage for a single 2-Gy dose, the slope of this plot was -0.0013 per fraction2 +/- 0.0097 (95% CL). The assumption of equal effect per fraction was therefore not invalidated in the kidney of the mouse. With a 5- instead of a 12-h interfraction interval, the 20-fraction schedule was 7% more effective as measured by the two assays analyzed together; this was significant at P = 0.0001. This shows that 5 h is not sufficient time between fractions for full repair to occur in the kidney, and underlines the need for intervals of at least 6 h between the doses in clinical radiotherapy using more than one fraction per day. The data are consistent with an alpha/beta ratio approximately 1.6 Gy, with a repair half-time approximately 1.3 h. However, these experiments were not designed to determine these parameters and their values should be regarded only as rough estimates.

Animals↗
PubMed2004

[Effect of fractions isolated from Naja naja atra venom on antioxidation in animals].

OBJECTIVE: To study the antioxidation of fraction F and H isolated from Naja naja atra venom on homogenate and RBC autoxidation. And to explore the effect of two fractions on the activities of antioxidation enzymes in mice. METHOD: Samples of tissues homogenates and RBC suspension were pretreated with fraction F/H, and then their generation of malondialdehyde(MDA) was examined. The effects of fraction F/H on O2-* produced by pyrogallol autoxidation and *OH produced by Cu2+ -VitC were checked. After being administrated i.p. with fraction F/H for 15 days, superoxide dismutase and hydroperoxidase in mice were measured for their activities. RESULT: Fraction F/H inhibited RBC autohemolysis and the generation of MDA decreased. The production of lipid peroxides in normal brain, liver and heart homogenate of rat and the elevation of lipid peroxides induced by cysteine and FeSO4 in homogenate were inhibited by addition of fraction F/H. The O2-* produced by autoxidation of pyrogallol and the *OH produced by Cu2+ -VitC system could be scavenged by fraction F/H (the potency of scavenging oxygen free radical is that fraction H > fraction F). Fraction F/H all increased the activities of several antioxidation enzymes in mice to different extents. CONCLUSION: Fraction F/H have the effect of antilipid peroxidation,may scavenge active oxygen free radical and increase the activity of SOD.

Animals↗
PubMed2006

[Distribution behaviors of phenanthrene to humic fractions in natural soil].

After adsorption of phenanthrene by the natural soil under different concentrations initially added, the soil sample was extracted for humic acid fraction (including humic acid and fulvic acid), and the sorption amount of phenanthrene in humin fraction was calculated to investigate the adsorption/distribution kinetics in two soil organic fractions and the corresponding influence of original phenanthrene concentration. The experimental data were fitted using Freundlich equation. The results show that, distribution of phenanthrene in the soil exhibited a multi-stage property, i.e., from a first fast sorption to a breakthrough at about 48 h, then followed by a slow sorption procedure. In the fast sorption stage (before 48 h), there was an up-to-down fluctuation of phenanthrene sorption ratio (sorption amount/added amount) in humic acid fraction, possibly due to surface sorption by minerals and competitive sorption by humin fraction. In the slow sorption stage, variations in sorption ratio in humic acid fraction was very small, and the influence of original concentration of phenanthrene was slight; while for humin fraction, the sorption ratio of phenanthrene at lower initial concentration was significantly higher than at higher one, in addition, the sorption ratio showed a gradually increasing trend, indicated humin fraction as the main domain in charge of the slow sorption. The fitting results of model parameters demonstrated that, sorption nonlinearity of phenanthrene in the natural soil increased in the following order: humic acid fraction< whole soil< humin fraction, and enhanced gradually. Different characteristics of humic acid and humin fractions in the multi-stage kinetics of phenanthrene sorption/distribution further reflected the effects of heterogenerity of soil organic fractions on nonlinear sorption behaviors.

Adsorption↗
PubMed1986

Influence of atrioventricular synchrony on hemodynamics in patients with normal and low ejection fractions following open heart surgery.

The authors wished to test the hypothesis that atrioventricular synchrony has a relatively greater effect on hemodynamic parameters in postoperative patients with low ejection fractions compared to those with normal ejection fractions. Temporary pacing wires were placed on the right atrium and right ventricle of patients undergoing open heart surgery. Duplicate thermodilution cardiac outputs were determined during atrial pacing and ventricular pacing at 100 beats/min. Mean left atrial and systemic blood pressures were monitored. Thirteen patients with ejection fractions of 45 per cent or less (range 24 to 45%, mean 37.3%) were included in the low ejection fraction group, and 27 patients with ejection fractions of 59 per cent or greater (range 59 to 80%, mean 66.8%) were considered in the normal ejection fraction group. All hemodynamic parameters improved significantly when changing from ventricular pacing to atrial pacing in both the normal ejection fraction group and low ejection fraction group (P less than 0.05). The magnitude of change between the groups showed no significant difference for all parameters except left atrial pressure, which decreased by a greater percentage in the low ejection fraction group with atrial pacing (P less than 0.001). The atrial contribution to hemodynamic enhancement is important in patients with normal and low ejection fraction following open heart surgery. Patients with low ejection fractions do not sustain a relatively greater reduction in cardiac output, stroke volume index, or systemic blood pressure with loss of atrioventricular synchrony when compared to patients with normal ejection fractions.

Cardiac Output↗
PubMed1985

Isolation of two unique fractions from the cerebrospinal fluid of Alzheimer disease patients.

The cerebrospinal fluid from five patients with Alzheimer disease and five age-matched controls was fractionated into 7 to 9 fractions utilizing chromatographic techniques. The cerebrospinal fluid from each of the five Alzheimer disease patients contained two fractions (fractions B and C) which were lacking in the cerebrospinal fluid of the five age-matched controls. In addition, when the elution profiles of the Alzheimer disease and control cerebrospinal fluid were compared, fraction A, which was found in every cerebrospinal fluid sample studied, was eluted slightly faster in the Alzheimer disease samples than in the cerebrospinal fluid samples from the age-matched controls. Furthermore, it is believed that fraction A isolated from the control cerebrospinal fluid consists of aggregated immunoglobulin molecules and that fraction A isolated from the Alzheimer disease patients' cerebrospinal fluid might consist of immune complexes. Each of the purified cerebrospinal fluid fractions from both control and Alzheimer disease patients was studied for its ability to inhibit macrophage mediated tumor cytotoxicity as well as activate macrophages to kill tumor cells. Each activate macrophages to kill tumor cells. None of the purified cerebrospinal fluid fractions obtained from the controls could inhibit macrophage mediated tumor cytotoxicity whereas 4 of the 9 purified fractions isolated from the Alzheimer disease patients inhibited macrophage mediated cytotoxicity by more than 50%. When fractions B and C were examined for their ability to either activate macrophages or inhibit macrophage mediated cytotoxicity, it was found that fraction B inhibited macrophage mediated cytotoxicity but was not able to activate macrophages to kill tumor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer Disease↗
PubMed1983

Phosphorylated nonhistone proteins in different fractions of rat liver nuclei obtained by metrizamide gradient centrifugation.

The distribution of nuclear nonhistone proteins (NHPs) labelled in vivo with 32P was investigated in different subnuclear fractions obtained by metrizamide gradient centrifugation of mildly sonicated rat liver nuclei. The bulk chromatin banding at 1.20-1.22 g to cm3 (fraction C) contained only minor amounts both of non-phosphorylated and 32P-labelled NHPs. Nick-translated DNA sequences were found to sediment at a slightly higher density (1.26 g/cm3) in a minor fraction (A). Fraction A also contained a significant portion of the newly synthesized RNA and was enriched additionally with a broad spectrum of NHPs; some of them were highly 32P-labelled. Two hnRNP fractions (R2 and R1) sedimenting at densities greater than 1.28 g/cm3 were analyzed, too. By SDS-PAGE it was shown that the most abundant 32P-NHPs were found in three groups (fraction A, R1, and R2). Two of them, 32-34 KDa, and 37-40 KDa, are components of the major proteins of the hnRNP particles. A group of four moderately labelled 32P-NHPs of approximately 55 K, 64 K, 70 K, and 90 KDa appeared substantially enriched in fraction A. They were found also in RNP fractions R1 and R2, but to a smaller mount. Therefore, we suggest that in fraction A they exist in a complex with hnRNP. Fraction A was also enriched with numerous 32P-NHPs of very high molecular weight found in other types of experiments nearly exclusively in the nuclear residual structures. The 32P-protein pattern of the nucleoli was shown to be different from that of the other subnuclear fractions. Considering our observations on the accumulation of nick-translated DNA sequences, the presence of newly synthesized RNA, the high content of NHPs, and the association of special 32P-NHPs we suggest that fraction A represents transcriptionally active chromatin.

Animals↗
PubMed1984

Response of 9L rat brain tumor multicellular spheroids to single and fractionated doses of 1,3-bis(2-chloroethyl)-1-nitrosourea.

This study was designed to examine the relative effect of each of four fractions of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) against 9L rat brain tumor multicellular spheroids and to compare the results of the cell survival and growth delay assays. Similar levels of cell kill resulted when BCNU was administered either as single fractions of 1.5, 3.0, 4.5, or 6.0 micrograms/ml for 1 hr or as one to four fractions of 1.5 micrograms/ml that were administered sequentially for 1 hr each. Survival was increased if the assay was delayed until 24 hr after drug treatment, which indicates that 9L cells in spheroids recover from BCNU-induced potentially lethal damage. When BCNU was administered in 1.5-micrograms/ml fractions, plating efficiencies depended markedly on the interval between the fractions. The 12-hr protocol produced an overall higher cell kill. Fractionation schedules of 24 and 36 hr produced less cell kill than did the other schedules. Survival plateaued for the last three treatments with BCNU in the 36-hr schedule. Cells in S phase at the time of administration of the initial 1.5-micrograms/ml fraction of BCNU moved into G1- and G2-M phases by 12 hr after treatment. For time periods longer than 12 hr, cells began to appear in the BCNU-resistant S phase. Thus, the movement of cells into the drug-sensitive and -resistant phases after the first fraction correlates well with the corresponding overall cytotoxic effect produced by treatment with the combined BCNU (1.5 micrograms/ml) fractions. For a higher concentration (3.0 micrograms/ml for 1 hr), maximum cell kill was reached within the 12- to 18-hr interval, after which cell kill plateaued. Cells were not found in the S-phase fraction 12 to 36 hr after the first treatment with 3.0 micrograms/ml; maximum cell kill for the fractionated protocols resulted at these times. Therefore, BCNU, which is classified as a cell cycle-nonspecific drug, can induce a partial synchrony in 9L spheroid cells, which determines the overall cytotoxicity produced by fractionated BCNU protocols. Although spheroids did not shrink during or after exposure to BCNU, growth was retarded by treatment with all doses and schedules. An optimum time point for growth delay measurement could not be determined from the data. However, correlations between cell survival and growth delay were obtained with arbitrarily chosen end point volumes of four and ten times the volume at the time of treatment.

Animals↗
PubMed1997

Clinical decision making based on radionuclide determined ejection fraction in oncology patients.

UNLABELLED: Decreased left ventricular ejection fraction (LVEF) is a relative contraindication for the use of potentially cardiotoxic chemotherapy. A resting LVEF of 50% is usually used as the lower limit of normal values. The decision to change chemotherapy, however, is complex and is affected by many factors, including ejection fraction. METHODS: To determine how LVEF data were used by clinical oncologists in clinical decision making, we performed a retrospective analysis of patients referred for ejection fraction measurements from the hematology/oncology divisionS of Stanford University from March 1992 through March 1995. The records of 565 patients treated with potentially cardiotoxic chemotherapy were evaluated. RESULTS: LVEFs < 50% were found in 153 patients. The charts of patients with reduced ejection fractions were reviewed to determine if the radionuclide measurement resulted in either discontinuation of the cardiotoxic agent or substitution of a less cardiotoxic drug or mode of administration. These specific changes in therapy occurred in only 43 of the 153 (28%) patients with ejection fractions below 50%; 24 of the 43 (57%) had ejection fractions < or = 40%. Patients with lower ejection fraction values were more likely to have their therapy changed than those with LVEFs close to normal. Patients with ejection fractions < or = 30 generally had cardiotoxic agents discontinued. Of patients who had a resting LVEF < 50% and whose therapy was not changed, 81% had a normal increase in LVEF with exercise. CONCLUSION: In clinical practice at our institution, ejection fraction < 50% is not used as an absolute contraindication to cardiotoxic chemotherapy. When the LVEF is less than 40%, potentially cardiotoxic therapy is most often discontinued or omitted. Radionuclide evidence of cardiac reserve may account for decisions to continue cardiotoxic agents despite ejection fractions < 50% in the majority of patients. Further study will be needed to establish standard criteria. Reserve function, as measured by the change in ejection fraction from rest to stress may be an important parameter used by oncologists to help select patients for continued therapy in spite of a reduced ejection fraction. Our results argue that use of fixed criteria may be too restrictive.

Antineoplastic Agents↗
PubMed1975

Uptake of dopamine into fractions of pig caudate nucleus homogenates.

Homogenates of the caudate nucleus of the pig were submitted to differential centrifugation. The 20000 g and 80000 g fractions were isolated and a part of them was osmotically shocked. The highest dopamine content per mg protein was found in the intact 80000 g fraction. Incubation experiments with the intact and the osmotically shocked fractions at 25 degrees C revealed that the particles of the intact 20000 g fraction took up dopamine, the influx of the amine was not enhanced by addition of ATP and magnesium to the incubation medium. On the other hand after osmotic shock the uptake of dopamine into the particles of this fraction was greatly enhanced by addition of ATP and magnesium. The uptake of dopamine into the particles of both intact and osmotically shocked 80000 g fractions was likewise enhanced by ATP and magnesium. The uptake in all fractions was not influenced by ouabain. The influx of dopamine into the particles of the intact 80000 g fraction was competitively inhibited by reserpine (Ki0.96 x 10-8M) and prenylamine (Ki1.74 x 10-8M). It is concluded that the intact 20000 g fraction contains intact synaptosomes; the uptake of dopamine is independent of the presence of ATP and magnesium. The shocked 20000 g fraction and the 80000 g fractions contain synaptic vesicles; the uptake of dopamine into these vesicles is enhanced by ATP and magnesium.

Adenosine Triphosphate↗