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PubMed1975

Phosphatidyglycerol in rat lung. II. Comparison of occurrence, composition, and metabolism in surfactant and residual lung fractions.

A comparison of the occurrence, fatty acid composition, and metabolism of phosphatidyglycerol and phosphatidylcholine in the surfactant and residual fraction of rat lung has been carried out. The surfactant and residual fractions were separated by discontinuous sucrose density gradient centrifugation. The surfactant fraction was found to contain 69 percent phosphatidylcholine and 7 percent phosphatidylglycerol. The residual fraction contained 46 percent phosphatidylcholine and 3 percent phosphatidylglycerol. Phosphatidylcholine and phosphatidylglycerol were found to contain 85 and 79 percent palmitate in the surfactant fraction and 67 and 68 percent in the residual fraction, respectively. Isolated rat lungs were perfused with medium containing [U-14C]glucose, [9,10-3H]palmitate, and [1-14C]acetate and the incorporation into palmitate isolated from the alpha and beta position of phosphatidylcholine and phosphatidylglycerol was determined. Each radioactive substrate was found to be incorporated into palmitate of phosphatidylcholine equally at the alpha and beta position of the surfactant fraction. In the residual fraction the specific activity of the beta position palmitate was found to be twice that of the alpha position. The incorporation of [9,10-3H]palmitate and [1-14C]acetate into palmitate at the alpha and beta positions of phosphatidylglycerol was similar in both the surfactant and residual fractions. In each case palmitate at the alpha position had approximately twice the specific activity of that at the beta position. The incorporation of [U-14C]glucose into phosphatidylglycerol of the surfactant fraction was, however, greater in palmitate at the beta position than at the alpha. The results show that phosphatidylglycerol is associated with the lung surfactant fraction and suggest that palmitate esterified to the alpha and beta positions of phosphatidylglycerol and phosphatidylcholine occurs at different rates and is dependent upon the precursor source of palmitate.

Animals↗

PubMed1982

Preparation of an insoluble fraction of ox brain and its affinity for Na+ and K+.

A water insoluble fraction was prepared from ox cerebrum by homogenization in water, dialysis against water, washing with water and drying in air at 293 degrees K. The fraction represented 15.5 +/- 3% (n = 8) of the weight of the fresh brain; it contained means of 81% (n = 6) of the lipid, found in freshly dried ox brain samples, and 46% (n = 5) (biuret method) or 51% (n = 3) (6) of the protein, respectively. The Na+ and K+ concentrations were measured by atomic emission flame photometry, firstly, in prepared media, and then after 4 ml of the same media had been mixed with 1 g of the insoluble fraction at 310 degrees K for 20 min; the concentration in the fraction was calculated from that found in the medium. The concentration in the medium (mM) after incubation was compared with that calculated to be in the fraction, (mumol/g). When the insoluble fraction was mixed with Krebs Ringer saline containing bicarbonate and glucose, modified so that the ratios of NaCl and KCl varied-(although together they always added up to 150 mM)-there was a mean of 2.6 times as much Na+ or K+ in the fraction (mumol/g) as in the media (mM) when the latter contained up to 80 mM Na+ or K+. When the concentration of the cations in the media exceeded this value, the concentration of Na+ in the fraction rose considerably, while the concentration of K+ fell to zero. When only Ca2+ or only Mg2+ was omitted from the Krebs-Ringer bicarbonate glucose saline, the fraction did not take up Na+ or K+ from the medium at any concentration. On electron microscopy the fraction was granular and amorphous and contained myelin figures. The fraction did not take up any significant volume of oxygen measured manometrically either in the modified Krebs-Ringer solutions or in a mitochondrial substrate.

Animals↗

PubMed1987

Profile of phospholipase A2 activity in subcellular fractions and lamellar bodies of developing, neonatal and adult rabbit lung. Correlation with intracellular levels of disaturated phosphatidylcholine.

Phospholipase A2 activity was determined in subcellular fractions and lamellar bodies of fetal, neonatal and adult rabbit lungs. Specific activity in most fractions decreased from the 24th to the 28th day of gestation. All fractions except the mitochondrial and the nuclear fractions exhibited a sharp increase in activity in the newborn lung. Specific activity in the adult lung generally declined in comparison to neonatal values. During gestation total enzyme activity per gram of lung was concentrated in the cytosolic fraction. With the exception of the lamellar body fraction, the total content of phospholipase A2 activity increased dramatically in all fractions from the neonatal lung. The lamellar body fractions displayed both low specific activity and low total enzyme activity during gestation. Specific activity increased dramatically in the neonatal and adult lung but still accounted for only a small fraction of the activity in comparison to the other subcellular fractions. The subcellular content of disaturated phosphatidylcholine (PC) appeared to correlate well with the activity of phospholipase A2 in the neonatal mitochondrial, microsomal and cytosolic fractions. Since decreasing prenatal enzyme levels are associated with increasing disaturated PC content, the alkaline and calcium-dependent phospholipase A2 may not be directly involved in disaturated PC synthesis in the fetus. However, postnatally, the correlation between the pattern of production of disaturated PC and the activity of the phospholipase A2 indicates a role for this enzyme in surfactant-related disaturated PC synthesis.

Animals↗

PubMedDate not supplied

Extraction of corticosterone from cell homogenates and subcellular fractions of the rat adrenal cortex. III. ACTH-induced temporal subcellular redistributions of steroid precursors to corticosterone.

Cholesterol, pregnenolone, progesterone, 11-deoxycorticosterone (11-DOC) and corticosterone were quantitated in subcellular fractions isolated from in vivo adrenocorticotropin (ACTH)-stimulated rat adrenal zona fasciculata/reticularis. Six adrenal subcellular fractions separated by discontinuous sucrose gradient centrifugation (lipid, 0.125 M sucrose, cytosolic, microsomal, mitochondrial and nuclear) were extracted with alkaline ether/ethanol and assayed by high pressure liquid chromatography (HPLC). Lipid fractions contained the major cholesterol stores, while most pregnenolone and progesterone was found in lipid, microsomal and mitochondrial fractions. The 0.125 M sucrose and cytosol fractions together contained approximately 75% of the total 11-DOC and corticosterone. The five steroids were only present in small amounts in organelle fractions containing steroidogenic enzymes. Homogenate and lipid fraction cholesterol decreased between 10 and 15 min and again 30 min after ACTH injection. In the homogenate, lipid, microsomal and mitochondrial fractions, pregnenolone and progesterone were increased after ACTH injection; peak pregnenolone and progesterone concentrations were often measured in adrenal gland sucrose, cytosolic, microsomal and mitochondrial fractions 15 to 20 min after rats were injected with ACTH. Although ACTH increased 11-DOC and corticosterone in all but the mitochondrial and nuclear fractions, the sucrose, cytosolic and microsomal 11-DOC, and cytosolic corticosterone increased most dramatically. In many fractions, peak 11-DOC and corticosterone concentrations were most often observed between the 10 and 15 min periods and again at 30 min.

Adrenal Cortex↗

PubMed2006

Fractionation of red wine polyphenols by solid-phase extraction and liquid chromatography.

A systematic method for separation of aged red wine polyphenols into various distinct fractions using combined techniques of solid-phase extraction and liquid chromatography was proposed. The aged red wine polyphenols were separated into various distinct fractions including phenolic acid fraction, monomer flavanol fraction, oligomer procyanidin fraction, anthocyanin and its pyruvic acid derivative fraction, free or non-colored proanthocyanidin fraction, fraction of direct condensation products between anthocyanins and proanthocyanidins and fraction of other pigmented complexes. The phenolic composition of each fraction was verified by HPLC with diode array detection (HPLC-DAD), thiolysis, vanillin assay, HPLC coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) and multi-stage MS fragment analysis. For the first time, anthocyanins and their pyruvic derivatives were separated from other phenolic compounds, while free or non-pigmented polymer proanthocyanidins from other pigmented complexes. The fractionation method would be of particular interest in further studying the detailed composition of polymeric polyphenols in red wine.

Chemical Fractionation↗

PubMed2004

Fractionation of peptides in proteomics with the use of pI-based approach and ZipTip pipette tips.

The aim of the work was to explore the utility of the in-solution isoelectric focusing (sIEF) fractionation method. That method was proved to be the alternative separation method of mixtures of protein tryptic digests in proteomics. Analysis of the identification of peptides was performed with the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). For that research, previously designed the miniaturized multi-chamber fractionation sIEF device (75 microl volume for each chamber) based on polyacrylamide gel membranes with immobilines technology was utilized. To evaluate the efficiency and accuracy of sIEF fractionation combined with MS/MS peptides identification, bovine serum albumin (BSA) digest and mixture of five proteins digest were used. First, fractionation of bovine serum albumin digest sample was performed using sIEF method. Studies performed for that simple mixture of peptides proved the ability of the sIEF device to focus peptides mostly in one chamber. Additionally performed the correlation analysis between pI(calc) and pI(exp) values for identified peptides proved the possibility to obtain experimentally useful high correlation. That information was found to have a potential value for construction of additional constraint during false positives evaluation process among identified proteins. Next, studies on the sIEF fractionation were combined with the evaluation of practical use of ZipTip pipette tips to fractionate peptides in the case of simple mixture of proteins. For this, five proteins digest samples were used. The analysis without prior any fractionation enabled to identify very limited number of proteins. The significant improvement was obtained when one used sIEF alone or with combination with ZipTips fractionation prior to MS analysis. The proposed approach based on in-solution isoelectric focusing proved to be an efficient and accurate alternative fractionation method of protein digests and can be considered as the first useful dimension in two-dimensional proteomics separations. Moreover, analytical information from that pI-based fractionation method can be considered as the additional source of database matching constraint. It can also be a valuable tool for analytical and bioinformatic studies of peptides fractionation in proteomics.

Amino Acid Sequence↗

PubMed2000

Change in radiosensitivity with fractionated-dose irradiation of carbon-ion beams in five different human cell lines.

PURPOSE: To investigate the change in the surviving fractions by fractionated-dose irradiations with carbon ions, based on the recovery of potentially lethal damage (PLDR) and the change of radiosensitivity by every fractionated-dose irradiation. METHODS AND MATERIALS: One normal human and four human-tumor cell lines were used. Cells were irradiated with carbon ions accelerated by the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences in Japan. The LET values were estimated to be 13.18 keV/microm for low-LET beams and 76.92 +/- 0.20 keV/microm for high-LET beams. Fractionated-dose irradiations were carried out with 5 fractions within a 24-h interval. RESULTS: The surviving fractions for the fractionated-dose irradiation with X-rays and carbon ions decreased exponentially with increasing the number of fractions in the tumor cell lines. In contrast, the surviving fractions for the carbon ions in normal human cells decreased exponentially as well as the tumor cell lines, while it tended to level off from the 3rd to the 5th fraction in the case of using X-rays. CONCLUSION: The change in both the recovery ratio of the PLDR and radiosensitivity by every fractionated-dose irradiation depends on individual cell lines and the quality of radiations.

Carbon↗

PubMed2001

Repopulation of FaDu human squamous cell carcinoma during fractionated radiotherapy correlates with reoxygenation.

PURPOSE: FaDu human squamous cell carcinoma (FaDu-hSCC) showed a clear-cut time factor during fractionated radiotherapy (RT) under ambient blood flow. It remained unclear whether this is caused solely by proliferation or if radioresistance resulting from increasing hypoxia contributed to this phenomenon. To address this question, repopulation of clonogenic FaDu cells during fractionated RT under clamp hypoxia was determined by local tumor control assays, and compared to the results after irradiation with the same regimen under ambient blood flow. METHODS AND MATERIALS: FaDu-hSCC was transplanted into the right hind leg of NMRI nu/nu mice. In the first set of experiments, irradiation was performed under clamp hypoxia. After increasing numbers of 3 Gy fractions (time intervals 24 h or 48 h), graded top-up doses were given to determine the TCD(50) (dose required to control 50% of the tumors). In the second set of experiments, all 3 Gy fractions were applied under ambient conditions, but as in the previous experiments the graded top-up doses were given under clamp hypoxia. A total of 26 TCD(50) assays were performed and analyzed using maximum likelihood techniques. RESULTS: With increasing numbers of daily fractions, the top-up TCD(50) under clamp hypoxia decreased from 39.4 Gy [95% CI 36, 42] after single dose to 19.8 Gy [15, 24] after 18 fractions in 18 days and to 37.8 Gy [31, 44] after 18 fractions in 36 days. The results were consistent with biphasic repopulation, with a switch to rapid repopulation after about 22 days [13, 30]. The clonogen doubling time (T(clon)) decreased from 9.8 days [0, 21] in the beginning of RT to 3.4 days after 22 days. Under ambient blood flow the top-up TCD(50) decreased from 37.6 Gy [34, 40] after single dose irradiation to 0 Gy [0, 1] after 18 fractions in 18 days and 22.4 Gy [18, 27] after 18 fractions in 36 days. Similar to results from irradiations under clamp hypoxia, the ambient data were consistent with a biphasic course of clonogen inactivation. Comparison of both data sets revealed significant reoxygenation after 12 fractions. CONCLUSIONS: Our data are most consistent with a biphasic course of clonogen repopulation during fractionated RT of FaDu-hSCC under clamp hypoxia with a switch in T(clon) after about 22 days of treatment ("dog-leg"). A similar biphasic course of cell repopulation was observed under ambient conditions. The temporal coincidence between repopulation and reoxygenation suggests that the latter might be the stimulus for proliferation in FaDu tumors.

Animals↗

PubMed1998

Altered fractionation trials in head and neck cancer.

Advancement in radiobiological concepts has led to the development of two classes of new fractionation schedules for the treatment of head and neck cancers. These altered fractionation regimens are referred to as hyperfractionation and accelerated fractionation schedules. Hyperfractionation exploits the difference in fractionation sensitivity between tumors and normal tissues manifesting late morbidity. In contrast, accelerated fractionations attempt to reduce tumor proliferation as a major cause of radiotherapy failure. Although there are many permutations in accelerating radiation treatment, the existing schedules can be conceptually grouped into two categories, pure accelerated fractionations and hybrid accelerated regimens, depending on whether there are concurrent changes in other fractionation parameters. The results of 10 completed phase III clinical trials addressing different types of altered fractionation schedules in head and neck carcinomas are examined and summarized in this review article. The data of trials on hyperfractionation regimens applying 10% to 15% total dose increment over the standard 66 to 70 Gy consistently revealed a 10% to 15% improvement in the local control rate of a subset of intermediate-stage carcinomas without an appreciable increase in the incidence of late complications. The available data on accelerated fractionation regimens showed that tumor clonogen proliferation is a major cause of radiation failure. Completed studies, however, revealed that a 1- to 1.5-week treatment acceleration without total dose reduction achieved by administering 2-Gy fractions 6 times per week or concomitant boost schedule yielded an approximately 15% higher tumor control rate without increasing late toxicity. Shortening the overall time to less than 2 weeks with an associated total dose reduction did not seem to improve tumor control rate, with an exception perhaps for a small subset of patients with laryngeal carcinomas, but might decrease some late normal tissue injury. A weekly dose accumulation rate of 14 Gy or greater, or delivery of 3 fractions of 1.6 Gy/d, with 6 hour intervals, without total dose reduction, was found to increase morbidity beyond the acceptable level. Further treatment refinements building on these findings are being pursued.

Dose Fractionation, Radiation↗

PubMed1989

The effects of fasting or hypoxia on rates of protein synthesis in vivo in subcellular fractions of rat heart and gastrocnemius muscle.

We measured rates of protein synthesis in vivo in subcellular fractions (soluble, myofibrillar and stromal fractions) of the heart and the gastrocnemius from rats after fasting or under hypoxic conditions (i.e. atmospheres containing 5% or 10% O2). Such interventions are known to inhibit protein synthesis under some circumstances. The recovery of tissue protein after fractionation was 80-100%. The proportions of protein present in the soluble and stromal fractions were different in the two muscles. The rates of protein synthesis in the myofibrillar and stromal fractions were less than those for total mixed tissue protein, whereas the rate for soluble protein was greater. Both fasting and moderate hypoxia (10% O2 for 24 h) inhibited protein synthesis in the gastrocnemius. In this tissue, the synthesis of the myofibrillar fraction was apparently the most sensitive to inhibition, and this resulted in some significant increases in the soluble-fraction/myofibrillar-fraction protein-synthesis rate ratios. In the heart, fasting inhibited protein synthesis, but moderate hypoxia (10% O2 for 24 h) did not. The rate of protein synthesis in the cardiac myofibrillar fraction was again more sensitive to fasting than were the rates in the other fractions, but it was not as sensitive as that in the gastrocnemius. Under severely hypoxic conditions (5% O2 for 1 or 2 h), protein synthesis was decreased in all fractions in both tissues. These results suggest that the rates of protein synthesis in these relatively crude subcellular fractions vary.

Animals↗

PubMed1981

Intracellular hormone receptors: evidence for insulin and lactogen receptors in a unique vesicle sedimenting in lysosome fractions of rat liver.

Previous studies have established the presence of polypeptide hormone receptors in Golgi fractions from rodent liver. In this study we attempted to identify peptide hormone receptors in other intracellular elements, particularly lysosomes. Tritosomes were prepared by a standard procedure, and highly purified secondary lysosomes were prepared by fractionating the L fraction of rat liver in a discontinuous metrizamide gradient into subfractions L1 to L4. Binding of 125I-labeled insulin and 125I-labeled somatotropin was studied with membranes prepared from osmotically shocked fractions. The L2 and L3 fractions, virtually devoid of galactosyltransferase (UDP galactose:2-acetamido-2-deoxy-D-glucosylglycopeptide galactosyltransferase, EC 2.4.1.38) but highly enriched in acid phosphatase [orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2], appeared as classical secondary lysosomes by electron microscopy. When compared with Golgi fractions, the level of specific binding per 50 micrograms of protein of 125I-labeled somatotropin in L2 and L3 was 1/3, whereas that of 125I-labeled insulin was comparable. L1, which was reduced in acid phosphatase and increased in galactosyltransferase activities, showed higher hormone binding than did L2 and L3. This was not attributable to Golgi fraction contamination, as evident by specific binding/galactosyltransferase ratios. Binding to tritosome membranes could be largely accounted for by variable contamination with Golgi fractions as judged by specific binding/galactosyltransferase ratios. To clarify the distribution of receptor sites in lysosomal preparations, we fractionated the entire L fraction on a continuous Percoll gradient. Acid phosphatase and galactosyltransferase activities were segregated to the high and low density ranges of the gradient, respectively; however, the fractions enriched in hormone binding were of intermediate density, distinct from Golgi and lysosomal biochemical markers. We conclude that intracellular receptors are found not only in galactosyltransferase-containing very low density lipoprotein-marked Golgi vesicles but also in a unique vesicle of intermediate density between classical Golgi and lysosomal structures.

Animals↗

PubMed2004

A high-throughput approach for subcellular proteome: identification of rat liver proteins using subcellular fractionation coupled with two-dimensional liquid chromatography tandem mass spectrometry and bioinformatic analysis.

Four fractions from rat liver (a crude mitochondria (CM) and cytosol (C) fraction obtained with differential centrifugation, a purified mitochondrial (PM) fraction obtained with nycodenz density gradient centrifugation, and a total liver (TL) fraction) were analyzed with two-dimensional liquid chromatography tandem mass spectrometry analysis. A total of 564 rat proteins were identified and were bioinformatically annotated according to their physicochemical characteristics and functions. While most extreme alkaline ribosomal proteins were identified in the TL fraction, the C fraction mainly included neutral enzymes and the PM fraction enriched alkaline proteins and proteins with electron transfer activity or oxygen binding activity. Such characteristics were more apparent in proteins identified only in the TL, C, or PM fraction. The Swiss-Prot annotation and the bioinformatic prediction results proved that the C and PM fractions had enriched cytoplasmic or mitochondrial proteins, respectively. Combination usage of subcellular fractionation with two-dimensional liquid chromatography tandem mass spectrometry was proved to be a high-throughput, sensitive, and effective analytical approach for subcellular proteomics research. Using such a strategy, we have constructed the largest proteome database to date for rat liver (564 rat proteins) and its cytosol (222 rat proteins) and mitochondrial fractions (227 rat proteins). Moreover, the 352 proteins with Swiss-Prot subcellular location annotation in the 564 identified proteins were used as an actual subcellular proteome dataset to evaluate the widely used bioinformatics tools such as PSORT, TargetP, TMHMM, and GRAVY.

Animals↗

PubMed1998

Altered fractionation in the management of head and neck cancer.

Progress in radiation science led to the development of two classes of biologically sound fractionation schedules for the treatment of head and neck cancers. These altered fractionation regimens are referred to as hyperfractionation and accelerated fractionation schedules. Hyperfractionation exploits the difference in fractionation sensitivity between tumours and tissues manifesting late morbidity and only minor variations exist among regimens tested. In contrast, accelerated fractionation attempts to reduce tumour proliferation as a major cause of radiotherapy failure. Although there are major permutations, the existing schedules can conceptually be grouped into two categories, namely pure accelerated fractionation and hybrid accelerated regimens, depending on whether there are concurrent changes in other fractionation parameters. The results of completed phase III clinical trials addressing different types of altered fractionation schedules in head and neck carcinomas are summarized and examined in this review paper. The data from trials on hyperfractionation regimens applying 10-15% total dose increment consistently revealed a 10-15% improvement in the local control rate of a subset of intermediate-stage carcinomas without increasing the incidence of late complications. The available data on accelerated fractionation regimens already showed that tumour clonogen proliferation is a major cause of radiation failure. However, completed studies revealed that a 1-1.5 week treatment acceleration without total-dose reduction, achieved by administering 2 Gy fractions six times per week or concomitant boost schedule, yielded a 15% higher tumour control rate without increasing late toxicity. Shortening the overall time to below 2 weeks with an associated total-dose reduction did not seem to improve the tumour control rate but might decrease some late normal-tissue injury. A weekly dose accumulation rate of > or =14 Gy or delivery of three fractions of 1.6 Gy per day, with a 6 h interval, without total-dose reduction was found to increase morbidity significantly. Further treatment refinements are being pursued based on these findings.

Clinical Trials, Phase III as Topic↗

PubMed1985

Isolation and characterization of an enriched Golgi fraction from neurons of developing rat brains.

We report a method for the isolation of enriched fractions of intact Golgi apparatus from neurons of 10- to 12-day-old rat brains. Neurons were prepared according to a modified method of Farooq and Norton [J. Neurochem. 31, 887-894 (1978)]. Golgi-enriched fractions were obtained after centrifugation of postmitochondrial supernatants in a discontinuous sucrose gradient. Golgi fractions 1 and 2, recovered at the interfaces of 28-34% and 34-36% sucrose densities, respectively, were examined with morphometric and enzymatic methods. Morphometric analyses showed that 21-34% of fraction 1 and 11-29% of fraction 2 consisted of intact Golgi apparatus. Lysosomes, mitochondria, ribosomes, and rough endoplasmic reticulum contaminated fraction 1 (6-10%) and fraction 2 (14-26%). Golgi fraction 1 showed a 25- to 65-fold enrichment over neurons of UDP Gal:GlcNAc galactosyltransferase, CMP-sialic acid:lactosylceramide sialyltransferase, and PAPS:cerebroside sulfotransferase activities. Golgi fraction 2 showed a 8- to 23-fold enrichment over neurons of the activities of the above glycolipid- and glycoprotein-synthesizing enzymes. The activities of the possible marker enzymes rotenone-insensitive NADH-cytochrome c reductase, succinate-cytochrome c reductase, and arylsulfatase were low or minimally elevated in the Golgi fractions. A sevenfold enrichment of Na+, K+-ATPase activities was found in the Golgi fractions. This is consistent either with significant plasma membrane contamination or with the presence of this enzyme in the neuronal Golgi apparatus.

Animals↗

PubMed1993

Age-related changes in the ceramide composition of the major gangliosides present in rat brain subcellular fractions enriched in plasma membranes of neuronal and myelin origin.

Age-related changes of the ceramide composition of gangliosides were studied in the synaptosomal and myelin fractions from rat brain, carrying plasma membranes of neuronal and glial origin, respectively. The five major gangliosides (GM1, GD1a, GD1b, GT1b, and GQ1b) present in these fractions were separated and quantitated by normal-phase HPLC. Each ganglioside was then fractionated by reverse-phase HPLC into the molecular species carrying a single long-chain base (LCB). The largely preponderant LCBs in the synaptosomal and myelin fractions were the C18:1 and C20:1. The content of C20:1 LCB, generally low at 1 month, increased with age in all analyzed gangliosides and in all subcellular fractions and was greater in the "b series" than in the "a series" gangliosides. Remarkably, GM1 was the only ganglioside where the proportion of LCB 20:1 was higher in the synaptosomal fraction than in the myelin fraction. The fatty acid composition of the C18:1 or C20:1 LCB species of the different gangliosides in the synaptosomal and myelin fractions did not undergo appreciable changes with age. Stearic acid was largely predominant in all the gangliosides of the synaptosomal fraction, more in the C18:1 than in the C20:1 LCB species (80-90% vs. 60-70%). The gangliosides of the myelin fraction were characterized by a lower content of 18:0 and a much higher content of 16:0 and 18:1 fatty acids than those of the synaptosomal fraction. Thus, the ceramide composition is different in the gangliosides of neuronal and myelin origin and appears to be subjected to an age-related control.

Aging↗

PubMedDate not supplied

Serial histopathological changes in irradiated guinea pig lung receiving conventional fractionated and hyperfractionated irradiation.

PURPOSE: To determine serial histopathological differences in guinea pig lungs receiving the same total dose as clinically used between conventional fractionated and hyperfractionated irradiation. METHODS AND MATERIALS: The guinea pigs received 80 Gy in 40 daily fractions of 2 Gy each (conventional fractionation), 80 Gy in 80 fractions of 1 Gy each twice a day (hyperfractionation), 81 Gy in 27 daily fractions of 3 Gy each (conventional fractionation), or 81 Gy in 54 fractions of 1.5 Gy each twice a day (hyperfractionation). We evaluated the histopathological changes of irradiated guinea pig lungs at 1, 2, 3, 6, 9, and 12 months after irradiation. RESULTS: The guinea pig lungs that received 81 Gy in 27 daily fractions showed histopathological changes of inflammation including formation of lymph follicles after 6 months. The lungs which received 81 Gy in 54 fractions showed similar but slightly less pronounced changes than those that received 81 Gy in 27 daily fractions. The guinea pig lungs of other groups showed no histopathological changes during the observation period. CONCLUSION: In hyperfractionated irradiation the damage to the guinea pig lung is quantitatively less than that occurring as a result of conventional fractionated irradiation of the same total dose.

Animals↗

PubMed1975

Effect of injection of nuclear fraction from Rhodamine sarcoma on turnover of liver catalase.

1) When nuclear fraction prepared from Rhodamine sarcoma (sarcoma nuclear fraction) was injected into mice three times every 24 hr, the catalase activity of the liver decreased to one-third of the original activity. 2) By the injection of sarcoma nuclear fraction into mice, the catalase activity with the soluble fraction from homogenates of the liver decreased more significantly than that with the particulate fraction from them. 3) Immunological titration proved that the decrease of catalase activity in the liver of mice injected with sarcoma nuclear fraction was brought about by decrease in the amount of catalase protein. 4) In the mice, whose liver catalase activity had been irreversibly inhibited by injection of 3-amino-1,2,4-triazole, the initial rate for the restoration of the liver catalase activity was significantly showed by further injection of sarcoma nuclear fraction. 5) When the inhibitor of catalase biosynthesis, allylisopropylacetamide, was injected into mice, the activity level of the liver catalase decreased. The extent of decrease by the injection of the inhibitor was slightly lower than that by the injection with sarcoma nuclear fraction, which was almost the same as the extent of decrease by the injection of sarcoma nuclear fraction plus allylisopropylacetamide. 6) It is conceivable that the catalase biosynthesis in the liver was inhibited by the injection of sarcoma nuclear fraction in almost the same manner as by the injection of allylisopropylacetamide. However, it is not certain whether the degradation of liver catalase was slightly stimulated by the injection of sarcoma nuclear fraction.

Allylisopropylacetamide↗

PubMed1990

Phospholipid synthesis in a membrane fraction associated with mitochondria.

A crude rat liver mitochondrial fraction that was capable of the rapid, linked synthesis of phosphatidylserine (PtdSer), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho) labeled from [3-3H] serine has been fractionated. PtdSer synthase, PtdEtn methyltransferase, and CDP-choline:diacylglycerol cholinephosphotransferase activities were present in the crude mitochondrial preparation but were absent from highly purified mitochondria and could be attributed to the presence of a membrane fraction, X. Thus, previous claims of the mitochondrial location of some of these enzymes might be explained by the presence of fraction X in the mitochondrial preparation. Fraction X had many similarities to microsomes except that it sedimented with mitochondria (at 10,000 x g). However, the specific activities of PtdSer synthase and glucose-6-phosphate phosphatase in fraction X were almost twice that of microsomes, and the specific activities of CTP:phosphocholine cytidylyltransferase and NADPH:cytochrome c reductase in fraction X were much lower than in microsomes. The marker enzymes for mitochondria, Golgi apparatus, plasma membrane, lysosomes, and peroxisomes all had low activities in fraction X. Polyacrylamide gel electrophoresis revealed distinct differences, as well as similarities, among the proteins of fraction X, microsomes, and rough and smooth endoplasmic reticulum. The combined mitochondria-fraction X membranes can synthesize PtdSer, PtdEtn, and PtdCho from serine. Thus, fraction X in combination with mitochondria might be responsible for the observed compartmentalization of a serine-labeled pool of phospholipids previously identified (Vance, J. E., and Vance, D. E. (1986) J. Biol. Chem. 261, 4486-4491) and might be involved in the transfer of lipids between the endoplasmic reticulum and mitochondria.

Animals↗