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Biomedical subjects

G Mills

Publications and source records attributed to G Mills.

At least 73 records · Page 4Linked to original sources
PubMed1986

Microalbuminuria in a diabetic population.

The aim of the report is to define that diabetic population which is to be recognised as at imminent, and possibly reversible, risk of diabetic nephropathy. The prevalence of 0.63% of diabetes in the Mosgiel practice population is confirmed. Of the 84 diabetics studied eight (9.5%) had proteinuria and an additional nine (10.7%) had microalbuminuria. The means of quantification of microalbuminuria as the urinary albumin/creatinine ratio has been documented for a New Zealand population.

Aged↗
PubMed1986

Functional differences in the interactions of glycosylation-deficient cell lines with fibronectin, laminin, and type IV collagen.

Fibronectin isolated from the conditioned medium of monolayer cultures of baby hamster kidney (BHK) cells and several ricin-resistant (Ric) mutants derived from them express differences in N-glycosylation. The asparagine-linked oligosaccharides of BHK cell-derived fibronectin consist largely of complex chains, whereas hybrid and/or high-mannose chains are present in the fibronectins of mutant cell lines. The fibronectins exhibiting different glycosylation patterns are incorporated to similar extents into the cell-layer of human skin fibroblasts. In contrast, mutant cells retain significantly less endogenously produced fibronectin than BHK cells and also incorporate less human cellular fibronectin into a pericellular matrix. In vitro adhesion assays show that mutant cells attach to and spread relatively poorly on fibronectin-or type IV collagen-coated substrata but interact as well as do BHK cells with a laminin substratum. These results indicate that asparagine-linked oligosaccharides of fibronectin are not required for the binding and incorporation of the molecule into cell layers, but, as constituents of other cellular glycoproteins, they do modulate the ability of BHK cells to interact with some matrix components.

Animals↗
PubMed1985

Hybrid sialylated N-glycans are minor constituents of normal BHK-cell glycoproteins and a prominent feature in glycoproteins of some ricin-resistant cell lines.

Baby-hamster kidney (BHK) cells were labelled metabolically by growth in media containing radioactive sugars and the asparagine-linked glycopeptides (N-glycans) obtained by Pronase digestion of disrupted cells were fractionated by chromatography on concanavalin A-Sepharose. About 2-3% of the total [3H]galactose- or [3H]fucose-labelled glycopeptides were found to be bound tightly to the lectin column and were eluted with 500 mM-methyl alpha-mannoside. Further analysis of these minor components by chromatography on Bio-Gel P4, lentil-lectin-Sepharose and DEAE-Sephacel and sensitivity to alpha-mannosidase indicates the presence in BHK-cell glycopeptides of hybrid structures of the following form: (Formula: see text) Similar structures were identified as major features of the glycoproteins of ricin-resistant mutants RicR17 and RicR19 as described previously for RicR21 cells [Hughes, Mills & Stojanovic (1983) Carbohydr. Res. 120, 215-234]. The RicR15 cell line also produces significant amounts of hybrid N-glycans. The studies show that the novel N-glycans accumulating in ricin-resistant mutants are derived by a metabolic pathway that exists to a minor extent in normal BHK cells.

Animals↗
PubMed1985

An evaluation of an inpatient cardiac patient/family education program.

A study to (1) evaluate the impact of a patient education program on the patient's knowledge regarding his/her illness and (2) identify obstacles to compliance behavior after discharge was conducted over a 2-year period. A population of 342 patients with ischemic heart disease was assigned to an inpatient cardiac patient education program consisting of five daily 1-hour classes. The following patient data were gathered: (1) assessment of the individual's knowledge of his/her illness; (2) selected sociodemographic information, (3) measures of general intelligence and problem-solving ability, and (4) motivation to alter risk factors. A measure of compliance with the prescribed treatment plan was obtained by telephone for all patients 4 weeks after discharge. Patients were randomly assigned such that one group received a pretest and a posttest assessment of knowledge while a second group received only the posttest assessment. A difference score t test on knowledge scores was statistically significant. A regression analysis of predictors of overall compliance scores after discharge demonstrated that indicators of motivation were most highly correlated with compliance. It was concluded that additional research is needed to identify: (1) types of information that enhance the patient's awareness of his/her illness and (2) program structures and techniques that enhance patient motivation to comply with a prescribed treatment plan.

Adult↗
PubMed1984

Galactosyl transferases of baby hamster kidney (BHK) cells. Characterization of two oligosaccharide products synthesised using bovine asialo submaxillary-gland mucin as acceptor.

Extracts of BHK (baby hamster kidney) cells catalyse incorporation of galactose from UDP-galactose into asialo bovine submaxillary gland mucin. The galactosylated oligosaccharide products were released by alkaline-borohydride treatment and purified by Bio-Gel P2 chromatography and high-performance liquid chromatography. The structures of the oligosaccharide sequences synthesised have been identified unequivocally by high resolution 500 MHz 1H-NMR as galactosyl-(beta 1----3) N-acetylgalactosamine and galactosyl (beta 1----4) N-acetylglucosaminyl (beta 1----3)-N-acetylgalactosamine. Characterization of the latter sequence shows the presence in bovine mucin of the type III core sequence N-acetylglucosamine-(beta 1----3) N-acetylgalactosamine. Fractionation of BHK cell extracts on alpha-lactalbumin-Agarose has shown that the (beta 1----4)-galactosyl transferase responsible for synthesis of the trisaccharide binds to alpha-lactalbumin, a modulator of the (beta 1----4)-galactosyl transferase involved in N-glycan assembly. The evidence that the same transferase activity may be responsible for galactose transfer to both O-glycans and N-glycans is discussed.

Animals↗
PubMed1983

Hybrid, sialylated N-glycans accumulate in a ricin-resistant mutant of baby hamster kidney BHK cells.

Glycoproteins synthesized in a ricin-resistant mutant of BHK cells, clone RICR21, were labelled by growth of the cells in radioactive D-mannose, D-glucosamine, or L-fucose. Glycopeptides obtained from disrupted cells by exhaustive digestion with Pronase were fractionated into components binding to concanavalin A-Sepharose and nonbinding components. The binding components eluted with methyl alpha-D-mannopyranoside were separated by gel filtration on Bio-Gel P-4 into two main subfractions: an oligomannosidic fraction that was susceptible to Jack bean alpha-D-mannosidase and a fraction that became totally degraded only in the additional presence of neuraminidase, beta-D-galactosidase, and N-acetyl-beta-D-glucosaminidase. Further analysis of the latter fraction by exoglycosidase digestion together with consideration of the known pathways for the biosynthesis of asparagine-linked sugar chains of glycoproteins was consistent with a "hybrid" structure containing a NeuAc leads to Gal leads to GlcNAc sequence linked to the alpha-D-mannosyl-(1 leads to 3) residue of the core sequence, and a terminal alpha-D-mannosyl group linked to the alpha-(1 leads to 6) branch of the core sequence. The hybrid fraction was labelled after growth of the cells in radioactive L-fucose and was adsorbed to a lentil lectin-Sepharose column indicating the presence of core fucosylation. The novel structure represented about 30-35% of the total cellular glycopeptides of RICR21 cells and was not present in the glycopeptides of normal, ricin-sensitive BHK cells. Conversely, double-branched (biantennary) complex N-glycans, a prominent constituent of BHK cell glycoproteins, were absent in RICR21 cells, and analysis of the nonbinding fraction obtained from concanavalin A-Sepharose indicated that triple- and quadruple-branched (tri- and tetra-antennary), complex N-glycans present in normal BHK cell glycoproteins were also absent.

Animals↗
PubMed1983

Analysis by lectin affinity chromatography of N-linked glycans of BHK cells and ricin-resistant mutants.

Normal baby hamster kidney (BHK) fibroblasts and ricin-resistant (RicR) mutants of BHK cells derived from them were labelled metabolically with [3H]mannose or [3H]fucose. Glycopeptides obtained by digestion of disrupted cells with Pronase were separated by affinity chromatography on concanavalin A-Sepharose. In the normal BHK cells major glycopeptide fractions were obtained consisting of tetra- and tri-antennary sialylated complex glycans, bi-antennary sialylated glycans, and neutral oligomannosidic chains. The majority of bi-antennary chains were shown to contain a fucosyl-(alpha 1-6)-N-acetylglucosaminyl sequence in the core region by their ability to bind to a lentil lectin affinity column. All of the mutant cell lines examined were found to accumulate oligomannosidic glycans in cellular glycoproteins: complex sialylated glycans were either absent or greatly reduced in amount. Analysis of fractions isolated from concanavalin A-Sepharose by Bio-Gel P-4 chromatography and glycosidase degradation indicated that the glycans accumulating in RicR14 cells have the general structure: (formula; see text) and derivatives having fewer alpha-mannosyl units. We have also analysed the glycopeptides released by trypsin treatment from the surface of the normal and mutant cells, as well as those obtained by proteolysis of fibronectin isolated from the medium. The glycopeptide profiles of the cell-surface-derived material and of fibronectin showed for the mutant cells a marked accumulation of oligomannosidic chains at the expense of complex oligosaccharide chains. Hence, the alterations in glycan structure detected in bulk cellular glycoproteins of RicR cells are expressed also in cell surface glycoproteins and in fibronectin, a secreted glycoprotein.

Animals↗
PubMed1982

Congenital dyserythropoietic anaemia type II (CDA-II): chromosomal banding studies and adherent cell effects on erythroid colony (CFU-E) and burst (BFU-E) formation.

Bone marrow CFU-E and BFU-E from a patient with CDA-II formed erythroid colonies and bursts which contained multinucleated erythroblasts in vitro. Adherent cell depletion of the patient's marrow increased CFU-E derived colonies six-fold (98 +/- 17 v. 640 +/- 15 per 10(5) marrow cells plated) and co-culture of CDA-II marrow adherent cells with CSA-II adherent cell depleted marrow significantly suppressed erythroid colony formation. Similar adherent cell suppression of the patient's BFU-E also occurred. Adherent cell depletion of normal marrow did not increase CFU-E derived colony formation (488 +/- 63 v. 495 +/- 108) and decreased BFU-E derived burst formation. Addition of normal adherent cells to normal marrow increased erythroid colony and burst formation. Karyotype and chromosomal banding studies of the patient's multinucleated cells did not show chromosomal inversions, deletions or translocations.

Adult↗
PubMed1981

The magnitude of metabolically induced changes in the density of human low-density lipoproteins.

Radiolabelled low-density lipoproteins (LDL), obtained from a patient with heterozygous, familial hypercholesterolaemia and from a normal subject, were injected into the patient and two normal subjects. Two approaches were made to evaluate the kinetics of metabolism of these LDL: (1) by serial measurements of radioactivity in serum, urine and the whole body; (2) by observing the density of the labelled LDL from serum using density-gradient ultracentrifugation. No significant change was seen in the model density of the LDL in either the patient or the normal subjects, but there were changes in the skewness of the radioactivity peaks. This contrasts with previously published findings in the guinea pig, in which LDL radioactivity gradually accumulated in the densest particles. The guinea pig findings suggested that lipoproteins in the LDL region are structurally modified during their intravascular circulation. The present study indicates that modification leading to changes in density does not occur to any significant degree in the human, whose LDL represent the end product of intravascular metabolism of apolipoprotein B-containing lipoproteins.

Adult↗
PubMed1980

Polypeptide heterogeneity of hamster and calf fibronectins.

The adhesive glycoprotein fibronectin has been isolated from fresh hamster plasma by affinity chromatography on gelatin coupled to Sepharose beads by the method of Engvall & Ruoslahti [Int. J. Cancer (1979) 20, 1-5]. Polyacrylamide-gel electrophoresis of material heated in sodium dodecyl sulphate and 2-mercaptoethanol shows two prominent polypeptide subunits of approx. mol.wts. 215 000 and 200 000, with variable amounts of lower-molecular-weight fragments. The unexpected polypeptide heterogeneity of different preparations of hamster fibronectins and bovine serum fibronectin is shown to be partly an artefact and is generated during isolation and storage of purified fibronectin. Treatment of each hamster fibronectin subunit or a smaller fragment of approx. mol.wt. 140 000 with thermolysin or trypsin after radioiodination produces similar patterns of tyrpsine-containing peptides, indicating similar primary amino-acid sequences. Antibodies raised against the major subunits of hamster plasma fibronectin were coupled to Sepharose beads and used in conjunction with gelatin affinity chromatography to isolate fibronectins extracted with urea from baby-hamster kidney (BHK) cells and present in the long-term culture medium of these cells. The cell and medium fibronectins are similar to hamster plasma fibronectin in amino-acid and carbohydrate composition and also produce very similar peptide 'maps'. We conclude that the various forms of hamster fibronectins are structurally analogous in agreement with indistinguishable biological properties in mediating the substance adhesion of BKH cells [Pena & Hughes (1978) Cell Biol. Int. Rep. 3, 339-344].

Amino Acids↗
PubMed1979

Two-dimensional electrophoresis of surface glycoproteins of normal BHK cells and ricin resistant mutants.

The surface glycoproteins of baby hamster kidney (BHK) cells were iodinated by lactoperoxidase and submitted to a two-dimensional electrophoresis procedure involving isoelectric focusing in the first dimension and SDS gel electrophoresis in the second dimension. After autoradiography a complex but reproducible pattern was obtained. The technique was then applied to the study of three ricin-resistant mutant clones with reduced rates of cell-cell and/or cell-substratum adhesion. Abnormal patterns were observed in all three mutant clones indicating different mechanisms of ricin resistance and identifying glycoproteins which may be involved in cellular interactions.

Cell Adhesion↗
PubMed1978

Effects of costimulator on immune responses in vitro.

We recently described a factor, costimulator, that is required for the concanavalin A-induced proliferation of CBA mouse thymocytes in vitro (see Reference 1). Using the costimulator dependence of mouse thymocytes as an assay, we have now determined that spleen cells from congenitally athymic (nude) BALB/c mice do not produce costimulator in response to Con A, and spleen cells depleted of Thy 1-positive cells do not respond to it in the presence of Con A. Thus, costimulator both requires thymus-derived (Thy 1+ lymphocytes for its production and has an effect on this type of cell. (However, the costimulator-producing and responsive cells may be different.) Purified costimulator preparations are a source of the required second component for the stimulation of adult, CBA/J thymic lymphocytes by PHA, normally a poor mitogen for these cells. They also enhance the level of DNA synthesis in a mixed leukocyte reaction, and the specific generation of cytotoxic lymphocytes to allogeneic tumor cells in vitro. Costimulator is not H-2 restricted in its effects, and it is produced in mixed leukocyte reactions. Finally, it has been possible to grow normal, primary thymic lymphocytes in culture for about 20 days by adding partially purified costimulator to the cultures.

Animals↗
PubMed1976

Intramural squamous cell carcinoma of the esophagus.

A case of squamous cell carcinoma arising from an esophageal intramural squamous epithelial cyst is reported. Review of the literature reveals no previous reports of malignant transformation of esophageal cysts, although there have been reports of approximately 64 cases of benign esophageal cysts, and 35 cases of carcinoma arising in esophageal diverticula. In the present case, there was a history of increasing dysphagia for 2 months. Esophagram demonstrated a 4.5-cm concentric narrowing of the proximal esophagus just below the superior esophageal ring. Esophagoscopies revealed an esophageal stricture with intact mucosa, and bronchoscopy showed the lesion to be producing tracheal deviation. Multiple esophageal biopsies revealed mild mucosal hyperplasia with deep submucosal inflammatory changes suggesting an underlying lesion. Despite lack of histologic proof of malignancy, the patient underwent radiation therapy and bleomycin chemotherapy on the basis of the highly suggestive radiographic findings, but died with bilateral bronchopneumonia 6 months after admission. Autopsy demonstrated a 1.5-cm long intramural esophageal squamous epithelial cyst, from which arose a locally invasive squamous cell carcinoma, without mucosal involvement or metastases. There was no demonstrable evidence of any associated esophageal diverticulum.

Aged↗
PubMed1976

Quantitative analysis of the proliferative activity induced in murine thymocytes by concanavalin A.

A quantitative analysis of the proliferative response induced in murine thymocytes by concanavalin A (Con A) is described. Exogenous 3H-thymidine labels 35 to 40% of the newly incorporated TMP residues under optimal conditions. The density label 5-bromo-2-deoxuridine (BrUdR) does not affect DNA metabolism in this system. With this nucleoside, it is shown that newly synthesized DNA is the result of semi-conservative replication, not repair. Double labeling of DNA provides a monitor for cells traversing the cell cycle (S phase to subsequent S phase). The average cycle time is 12.5 hr, and the shortest cell cycle time is 10 hr. The growing fraction of active cells is about two-thirds. The data show that different subpopulations of thymocytes begin proliferating after various times in culture. Once effectively stimulated by Con A, some of the cells can traverse the cell cycle at least twice more after the mitogen is removed.

Animals↗