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Biomedical subjects

M Butler

Publications and source records attributed to M Butler.

At least 199 records · Page 11Linked to original sources
PubMed1966

Compraison of mycoplasmas associated with human tumors, leukemia, and tissue cultures.

Leach, R. H. (Wellcome Research Laboratories, Beckenham, Kent, England), and M. Butler. Comparison of mycoplasmas associated with human tumors, leukemia, and tissue cultures. J. Bacteriol. 91:934-941. 1966.-Mycoplasmas originally isolated by various workers from tissue cultures prepared from or inoculated with tumor or leukemic cells fell into four groups; each related to existing species or serotypes. These were Mycoplasma pulmonis, M. fermentans, M. hominis, and the GDL serotype, the last two being well known as contaminants of uninoculated cell lines. All the test strains were able to grow well in certain tissue cultures, and some caused cytopathic effects and acidity. These observations are discussed in terms of the relationship of these strains to the malignant tissues with which they were originally associated. The variable results obtained in certain biological tests on these strains emphasized the need for standardization of the conditions under which such tests may be employed to assist in identification of Mycoplasma species.

Acids↗
PubMedDate not supplied

Geriatric rehabilitation nursing.

This article is derived from a statement initially developed by the author for the Gerontology Special Interest Group of the Association of Rehabilitation Nurses. It draws on the standards and scope of practice of rehabilitation nursing as established by the American Nurses Association and the Association of Rehabilitation Nurses. The article provides insight into the needs of the elderly individual in the healthcare system; ultimately, its focus is on the necessity of providing responsible rehabilitation nursing care for clients with varied gerontological problems by evaluating and promoting restorative function. Rehabilitation nursing joins with gerontology to assist elderly clients in meeting individual goals.

Activities of Daily Living↗
PubMedDate not supplied

Comparisons of the glycosylation of a monoclonal antibody produced under nominally identical cell culture conditions in two different bioreactors.

The murine B-lymphocyte hybridoma cell line, CC9C10, was grown in serum-free continuous culture at steady-state dissolved oxygen (DO) concentrations of 10%, 50%, and 100% of air saturation in both LH Series 210 (LH) and New Brunswick Scientific (NBS) CelliGen bioreactors. All culture parameters were monitored and controlled and were nominally identical at steady state in the two bioreactors. The secreted monoclonal antibody (mAb), an immunoglobulin G(1), was purified and subjected to enzymatic deglycosylation using peptide N-glycosidase F (PNGase F). Asparagine-linked (N-linked) oligosaccharide pools released from mAb samples cultured in each bioreactor at each of the three DO setpoints were analyzed by high-pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The predominant N-linked structures were core-fucosylated asialo biantennary chains with varying galactosylation. There were also minor amounts of monosialyl oligosaccharides and trace amounts of afucosyl oligosaccharides. The level of DO affects the glycosylation of this mAb. A definite reduction in the level of galactosylation of N-glycan chains was observed at lower DO in both bioreactors, as evidenced by prominent increases in the relative amounts of agalactosyl chains and decreases in the relative amounts of digalactosyl chains-with the relative amounts of monogalactosyl chains being comparatively constant. However, the quantitative results are not precise matches between the two bioreactors. The effect of DO on galactosylation is less pronounced in the NBS bioreactor than in the LH bioreactor, particularly the shift between the relative amounts of agalactosyl and digalactosyl chains in 10% and 50% DO. There are also perceptibly higher levels of sialylation of the mAb glycans in the NBS bioreactor than in the LH bioreactor at all three DO setpoints. The results indicate that the DO effect is not bioreactor specific and that nominally identical steady-state conditions in different chemostat bioreactors may still lead to some incongruities in glycosylation, possibly due to the particular architectures of the bioreactors and the design of their respective monitoring and control systems. The observed differences in N-linked glycosylation of the mAb secreted by the hybridoma grown in the LH and NBS bioreactors may be explained by the differences in oxygen supply and control strategies between the two bioreactors.

Amidohydrolases↗
PubMedDate not supplied

Effect of ammonia on the glycosylation of human recombinant erythropoietin in culture.

Recombinant human erythropoietin (EPO) was produced by a stable transfected CHO-K1 cell clone (EPO-81) grown in serum-free medium. Our previous work showed that there was a significant increase in the heterogeneity of the glycoforms of EPO and a reduction of the sialylation at 20 mM NH(4)Cl. In the work presented here, the effects of ammonia on EPO N-linked oligosaccharides were analyzed. EPO was purified from culture supernatants by immunoaffinity chromatography. The N-linked oligosaccharides were released enzymatically and analyzed by fluorophore-assisted carbohydrate electrophoresis (FACE) and HPLC. The FACE N-linked oligosaccharide profile showed that the sialylated glycans contain one prominent band at a position corresponding to eight glucose units. The density of the major band was greatly diminished and the width was significantly increased in cultures containing added ammonia. The proportion of tetraantennary structures was reduced by 60%, while the tri- and biantennary structures were increased proportionally in the presence of ammonia. Glycan analysis by HPLC using a weak anion exchange column showed that the most significant characteristic effect of ammonia was a reduction of the proportion of glycans with four sialic acids from 46% in control cultures to 29% in ammonia-treated cultures. Analysis of the desialylated glycans by normal phase chromatography indicated a distribution of tetra-, tri-, and biantennary structures similar to that shown by FACE. The N-linked glycan sequence was determined by sequential exoglycosidase digestion followed by FACE. The results indicated a typical N-linked complex oligosaccharide structure. Glycans from ammonia-containing cultures showed the same sequence pattern. In conclusion, we showed that ammonia in the culture medium affected EPO glycosylation, which was observed as a reduction of the tetraantennary and tetrasialylated oligosaccharide structures. However, the presence of ammonia in the cultures did not change the oligosaccharide sequence.

Ammonia↗
PubMedDate not supplied

Application of a serum-free medium for the growth of Vero cells and the production of reovirus.

Two strains of reovirus (serotype 1 Lang/TIL and serotype 3 Dearing/T3D) were propagated in Vero cells grown in stationary or agitated cultures in a serum-free medium, M-VSFM. Solid microcarriers (Cytodex-1) were used to support cell growth in agitated cultures with a normal doubling time of 25 h. Cell yields of 1 x 10(6) cells/mL were obtained from an inoculum of 2 x 10(5) cells/mL in 4 days in microcarrier cultures. The growth profile and cell yield was not significantly different from serum-supplemented cultures. The virus titer increased by 3-4 orders of magnitude over a culture period of 150 h. The maximum virus titer in stationary cultures reached >1 x 10(9) pfu/mL for both strains of reovirus in M-VSFM. M-VSFM also supported high viral yields in microcarrier cultures. Both the specific productivity and final viral yield was higher in M-VSFM than serum-supplemented cultures. The high viral productivity suggests that this is a suitable system for the production of reovirus as an oncolytic agent for human therapeutic use.

Animals↗
PubMedDate not supplied

Effects of ammonia and glucosamine on the heterogeneity of erythropoietin glycoforms.

Recombinant human erythropoietin (EPO) is a glycoprotein produced as a therapeutic agent from mammalian cell cultures for the treatment of anemia associated with severe kidney damage. The EPO structure has a high glycan content which is essential for bioactivity but shows considerable molecular heterogeneity. The cell culture conditions that affect the heterogeneity of the glycoforms of EPO are not well understood. However, the accumulation of ammonia in culture is one factor that has been associated with an enhanced heterogeneity of glycoforms. In this report we investigate the metabolic perturbations associated with ammonia and glucosamine that may give rise to an altered pattern of EPO glycosylation. Recombinant human erythropoietin was synthesized in serum-free cultures of transfected Chinese hamster ovary (CHO) cells. The molecular heterogeneity of erythropoietin was increased by supplementation of cultures with either ammonia or glucosamine. The enhanced molecular heterogeneity was shown to be due to variable glycosylation that resulted in EPO with an enhanced molecular weight and isoelectric point range. Enzymatic removal of the glycan moiety of EPO in all cases resulted in a single molecular form with a molecular weight of 18 000, which corresponded to non-glycosylated EPO. The variable glycosylation was consistent with reduced sialylation and antennarity of the carbohydrate structures present on the three N-linked sites of EPO. In the presence of ammonia (>30 mM) the proportion of tetrasialylated and tetraantennary glycan structures were reduced by 73% and 57%, respectively, as determined by HPLC analysis. Such changes were also observed, although to a lesser extent (41% and 37%), by an increase in the glucosamine concentration (>10 mM) in the medium. The enhanced heterogeneity of the glycan structures coincided with a significant increase in the intracellular UDP-N-acetylhexosamine (UDP-GNAc) pool. The measured UDP-GNAc level was up to 2 orders of magnitude higher in the presence of either glucosamine or ammonia. However, the changes in the glycosylation profiles induced by either glucosamine or ammonia were significantly different even at the same intracellular UDP-GNAc concentration. This suggests that the enhanced EPO heterogeneity could not be mediated solely by the increased UDP-GNAc level. Glucosamine (but not ammonia) was shown to cause significant inhibition of glucose transport into the cells, which could induce a different pattern of primary metabolism.

Ammonia↗
PubMedDate not supplied

Calcium-dependent degradation of surfactant protein A by activated neutrophils due to serine proteases.

The effects of activated leukocytes on surfactant function and composition were examined to better define the mechanisms by which acute inflammation contributes to respiratory distress syndrome (ARDS). Peripheral blood leukocytes from healthy volunteers were incubated in vitro with surfactant for 4 hours: (1) in the absence of activation; (2) following activation by addition of phorbol myristate acetate (PMA); (3) following addition of PMA + FeCl2/EDTA; (4) PMA + FeCl2; (5) PMA + EDTA; (6) PMA + FeCl2 + superoxide dismutase (SOD) + catalase; (7) PMA + EDTA + serine or cysteine protease inhibitors. Surfactant was then repurified by sucrose gradient centrifugation, and function, phospholipid and protein composition, and extent of lipid peroxidation were assessed. PMA caused activation of leukocytes as detected by dichlorofluorescene assay. Lipid peroxidation (assessed by conjugated diene assay) was detected in all samples containing PMA. Abnormal function was noted in surfactant exposed to activated cells with 1 mM EDTA, whereas activation alone, or with FeCl2, had no effect. SOD + catalase prevented lipid peroxidation, but did not prevent leukocyte-mediated dysfunction, which was associated with a marked reduction in surfactant protein A (SP-A), but no detectable change in surfactant protein B (SP-B) or phospholipid composition. Serine protease inhibitors prevented SP-A degradation and dysfunction, whereas cysteine protease inhibitors had no protective effect. Addition of purified SP-A (5% w/w) to dysfunctional surfactant restored normal function, while SP-B/C mixture (3%) did not. Activated leukocytes cause surfactant dysfunction in vitro by serine protease-mediated degradation of SP-A, which occurs only in the presence of EDTA, and is prevented by addition of calcium. Although lipid peroxidation mediated by leukocyte release of free-radical products was also detected, surfactant dysfunction appears to be unrelated to this process.

Albumins↗
PubMedDate not supplied

Evaluation of the renal effects of an antisense phosphorothioate oligodeoxynucleotide in monkeys.

Antisense phosphorothioate oligodeoxynucleotides are therapeutic agents that provide target specificity resulting from Watson-Crick base pairing. However, there are nonspecific effects that in some instances result in toxicity. These compounds accumulate in the kidney and induce renal proximal tubular degeneration at high doses. The relationship between accumulation of phosphorothioate oligodeoxynucleotides in the kidney, indicators of renal toxicity, and histomorphology were investigated in rhesus monkeys. Monkeys received vehicle or an escalating dose regimen of 3, 10, 40, and 80 mg/kg of ISIS 2105 and were then evaluated for changes in clinical pathology indices, urinalysis parameters, and renal histopathology. Urinalysis revealed an increase in protein levels and a slight increase in blood content following the third 40 mg/kg dose and continuing through the 80 mg/kg doses, whereas other urinary markers of renal toxicity were unchanged. Creatinine clearance was slightly decreased in monkeys during the 80 mg/kg dose cycle. Granulation in the cytoplasm of proximal tubular epithelial cells was evident by microscopic examination of kidney and was present at all doses examined and increased with dose. Immunohistochemical staining localized the oligodeoxynucleotide within these granules. Histopathologic changes consisting of minimal to moderate tubular degeneration were present only at the higher doses of 40 and 80 mg/kg and at high tissue concentrations, and these changes occurred concurrent with functional alterations, whereas lower doses (< or = 10 mg/kg) did not affect a pathologic or functional change.

Animals↗