Search PubMed⌕ Search

Biomedical subjects

T J Higgins

Publications and source records attributed to T J Higgins.

At least 73 records · Page 4Linked to original sources
PubMed1983

Metabolism of palmitate by anoxic and reoxygenated heart cell cultures.

Under anoxic incubation conditions heart cell cultures showed enhanced uptake of [U-14C]palmitic acid into neutral lipids, while incorporation into phospholipids was unaltered. Fractionation of the neutral lipids showed greatest incorporation of radiolabel into the triglyceride fraction. Uptake of fatty acid in normoxic cultures may be dependent upon the supply of glycerol 3-phosphate from glycolysis, as 2-deoxyglucose and L-lactate, respectively, inhibited and stimulated incorporation of fatty acid into neutral lipid fractions. When previously anoxic cultures were reoxygenated, oxidation of fatty acid was depressed and the mitochondrial function of anoxic cultures appeared to be more readily uncoupled by 2,4-dinitrophenol, in comparison with cultures maintained under normoxic conditions. Similar behaviour was seen when oxidation of endogenous lipid or oxidation of glucose was examined. Previously anoxic cultures show a preference for oxidation of endogenous rather than exogenous lipid substrates. The results suggest that anoxia-stimulated lipid accumulation may prove injurious to subsequent mitochondrial function and may be a contributory factor in the pathological processes associated with hypoxic injury of cardiac tissue.

2,4-Dinitrophenol↗
PubMed1983

Periodontal disease in five and six year old children.

The purpose of this study was to determine the prevalence and severity of gingivitis in a sample of primary school children. One hundred and twenty eight children with an average age of 6 years 0 months (SD +/- 4 months) were examined for oral hygiene status using the Plaque Index (Pl.I.) and the Calculus Index (C.I.). The periodontal status was assessed using the Gingival Index (G.I.) and recording gingival sulcus depths about selected teeth. The significance of factors associated with the G.I. was determined using multiple classification analysis. The incorporated factors were Pl.I., age and sex. The scores for Pl.I., and G.I., and Pl.I. and sulcus depth were significantly correlated. The majority of children had a maximum Pl.I. score of 2, a maximum C.I. score of 0, a maximum G.I. score of 1, and maximum sulcus depth of 2 mm. The regressands Pl.I. and age used in the multiple classification analysis explained only 28% of the variance in the G.I. data. Also, the analysis did not indicate the children's sex as a significant source of explanation for the variance of the G.I.

Australia↗
PubMed1982

Automated rosetting assay for cell surface antigens and autorosetting lymphocytes.

An automated procedure, using a Coulter counter, is described for enumerating rosette-forming lymphocytes in 2 rosetting systems in mice, detecting antibodies to cell surface antigens, and the interaction of autologous erythrocytes with thymocytes (autorosetting). The procedure gives results comparable with determinations of rosettes by light microscopy. The procedure not only estimates rosetting percentages, but can be used to titrate anti-lymphocyte antibodies, to detect autorosette inhibition factor in serum and to assay cell surface antigens in detergent lysates of spleen cells.

Animals↗
PubMed1982

Latex bead rosetting method for cell surface antigens.

Polystyrene latex beads coupled with anti-Ig can be used to detect the binding of specific antibodies to target cells. The optimal conditions for coupling anti-Ig to beads are described. This method is as sensitive as red cell rosetting and has the advantages that coupling is simple and the coated beads stable.

Animals↗
PubMed1982

Role of the endoplasmic reticulum in the synthesis of reserve proteins and the kinetics of their transport to protein bodies in developing pea cotyledons.

Developing pea (Pisum sativum L.) cotyledons were labeled with radioactive amino acids, glucosamine, and mannose in pulse an pulse-chase experiments to study the synthesis, glycosylation, and transport of the reserve proteins vicilin and legumin to the protein bodies. Tissue extracts were fractionated on sucrose gradients to isolate either the endoplasmic reticulum (ER) or the protein bodies. Immunoaffinity gels were used to determine radioactivity in the reserve proteins (legumin and vicilin). After pulse-labeling for 45 min with amino acids, about half the total incorporated radioactivity coincided closely with the position of the ER marker enzyme NADH-cytochrome c reductase at a density of 1.13 g . cm-3 on the sucrose gradient. Both radioactivity and enzyme activity shifted to a density of 1.18 g . cm-3 in the presence of 3 mM MgCl2 indicating that the radioactive proteins were associated with the rough ER. Approximately half of the incorporated radioactivity associated with the rough ER was in newly synthesized reserve protein and this accounted for 80% of the reserve protein synthesized in 45 min. Trypsin digestion experiments indicated that these proteins were sequestered within the ER. In pulse-chase experiments, the reserve proteins in the ER became radioactive without appreciable lag and radioactivity chased out of the ER with a half-life of 90 min. Radioactive reserve proteins became associated with a protein body-rich fraction 20-30 min after their synthesis and sequestration by the ER. Pulse-chase experiments with radioactive glucosamine and mannose in the presence and absence of tunicamycin indicated that glycosylation of vicilin occurs in the ER. However, glycosylation is not a prerequisite for transport of vicilin from ER to protein bodies. Examination of the reserve protein polypeptides by SDS PAGE followed by fluorography showed that isolated ER contained legumin precursors (Mr 60,000-65,000) but not the polypeptides present in mature legumin (Mr 40,000 and 19,000) as well as the higher molecular weight polypeptides of vicilin (Mr 75,000, 70,000, 50,000, and 49,000). The smaller polypeptides of vicilin present in vicilin extracted from protein bodies (Mr 12,000-34,000) were absent from the ER. The results show that newly synthesized reserve proteins are preferentially and transiently sequestered within the ER before they move to the protein bodies, and that the ER is the site of storage protein glycosylation.

Biological Transport↗
PubMed1982

Assembly of storage protein oligomers in the endoplasmic reticulum and processing of the polypeptides in the protein bodies of developing pea cotyledons.

Cotyledons of developing pea seeds (pisum sativum L.) were labeled with radioactive amino acids and glucosamine, and extracts were prepared and separated into fractions rich in endoplasmic reticulum (ER) or protein bodies, The time-course of synthesis of the polypeptides of legumin and vicilin and the site of their assembly into protein oligomers were studied using immunoaffinity gels and sucrose density gradients. When cotyledons were pulse-labeled (1-2 h), newly synthesized vicilin was present as a series of polypeptides with M(r) 60,000-65,000, and newly synthesized vicilin was present as series of polypeptides with M(r) 75,000, 70,000, 50,000, and 49,000. These radioactive polypeptides were found primarily in the ER (Chrispeels et al., 1982, J Cell Biol., 93:5- 14). During a subsequent chase period, newly synthesized reserve proteins were initially present in the protein bodies in the above-named polypeptides. Between 1 and 20 h later, radioactive legumin subunits (M(r) 40,000 and 19,000) and smaller vicilin polypeptides (M(r) 34,000, 30,000, 25,000, 18,000, 14,000, 13,000, and 12,000) appeared in the protein bodies. The appearance of these labeled polypeptides in the protein bodies was not the result of a slow transport from the ER (or cytoplasm). Newly synthesized legumin and vicilin polypeptides were assembled into oligomers of 8S and 7S, respectively, in the ER. They appeared in the protein bodies in these oligomeric forms before the appearance of the smaller polypeptides (M(r) less than 49,000). These results indicate that the smaller vicilin polypeptides (M(r) less than 49,000) arise delayed posttranslational processing of some or all of the larger vicilin polypeptides. The precursors of legumin are completely processed in the protein bodies 2-3 h after their synthesis. The processing of the vicilin precursors is much slower (6-20 h) and only a fraction of the precursor molecules are processed. As a result both large (M(r) more than 49,000) and small polypeptides of vicilin accumulate in the protein bodies, whereas legumin accumulates only as polypeptides of M(r) 40,000 and 19,000.

Endoplasmic Reticulum↗
PubMed1982

Characterization of the alpha-Amylases Synthesized by Aleurone Layers of Himalaya Barley in Response to Gibberellic Acid.

The gibberellic acid (GA(3))-induced alpha-amylases from the aleurone layers of Himalaya barley (Hordeum vulgare L. cv Himalaya) have been purified by cycloheptaamylose-Sepharose affinity chromatography and fractionated by DEAE-cellulose chromatography. Four fractions (alpha-amylases 1-4) were obtained which fell into two groups (A and B) on the basis of a number of characteristics. Major differences in serological characteristics and in proteolytic fingerprints were found between group A (alpha-amylases 1 and 2) and group B (alpha-amylases 3 and 4). Also, the lag time for appearance of group B enzyme activity was longer than for group A, and the appearance of group B required higher GA(3) levels than group A. The components of each group behaved similarly, although differences in proteolytic fingerprints were detected.These results together with those from other studies indicate that GA(3) differentially controls the expression of two alpha-amylase genes or groups of genes giving rise to two groups of alpha-amylases with many different properties.

Journal Article↗
PubMed1981

A sensitive and quantitative fluorescence assay for cell surface antigens.

A procedure is described for the assay of cell surface antigens based on quantitative fluorometry. Fluorescent immunospheres are coupled with sheep anti-mouse immunoglobulins or Protein A and used to detect specific antibody bound to target cells. The fluorescent sphere assay described here offers 16--128-fold greater sensitivity than complement mediated lysis or Protein A radioimmune assays and comparable sensitivity to rosetting assays. In addition, the assay is simple to perform, uses commercially available reagents and is completely objective in that a common laboratory fluorometer is used to obtain fluorescence measurements.

Animals↗
PubMed1981

Liposomes containing myelin basic protein (BP) suppress but do not induce allergic encephalomyelitis in Lewis rats.

The ability of rats to respond immunologically to myelin basic protein (BP) incorporated into liposomes was tested. BP-liposomes administered intradermally or intravenously to naive rats were non-encephalitogenic, did not induce antibody or cellular reactivity to BP, nor did they protect against a subsequent challenge with BP in complete Freund's adjuvant (CFA). Intravenous administration of BP-liposomes to sensitized rats, however, suppressed EAE if given shortly before the expected onset of clinical signs. The same dose of BP in saline fails to suppress the appearance of clinical experimental allergic encephalomyelitis (EAE).

Adjuvants, Immunologic↗
PubMed1981

Reactivity of xenogeneic antihuman Ia antisera with the I-C subregion of the murine major histocompatibility complex. II. Biochemical studies.

The biochemical nature of the cross-reactive antigens on murine B cells, detected with xenogeneic antihuman Ia (H.Ia) sera, were examined. These antigens, coded for by the I-C subregion, were found to be carbohydrate in nature and probably exist as glycolipids on the cell surface. Furthermore, sugar inhibition studies demonstrated that the anti-H.Ia sera recognized identical monosaccharide residues on murine and human B cells.

Animals↗