PubMed Health⌕ Search

Biomedical subjects

D Nixon

Publications and source records attributed to D Nixon.

29 records · Page 2Linked to original sources
PubMed1986

National nutrition month: promoting the diversified role of dietitians as health care professionals.

In summary, the planning and directing of NNM activities for a large metropolitan hospital required extensive public relations efforts to assure the success of each event. NNM provided a unique opportunity for health care professionals to interact with the business community, therefore promoting a positive image of dietitians as professionals. The events, successful in promoting nutrition education, identified dietitians as nutrition experts.

Dietetics↗
PubMed1985

Successful chemotherapy for cystosarcoma phyllodes in a young woman.

Cystosarcoma phyllodes is a rare neoplasm of the breast. The tumor contains both stromal and epithelial elements. Local excision or simple mastectomy is usually curative. Most recurrences are local and can be controlled with excision. We treated a 23-year-old woman in whom disease had metastasized to the lungs with six courses of doxorubicin hydrochloride and cisplatin at three-week intervals and achieved complete remission.

Adult↗
PubMed1985

Bioenergetic studies in adult patients recovering from semi-starvation.

A model of energy-nitrogen balance developed in animals was adapted to the study of human bioenergetics. By creating balance conditions and steady-state formula infusion rates, each of the needed components of energy and nitrogen balance can now be measured with a high level of accuracy. A comprehensive description of energetic efficiency at the whole body level is possible using appropriate mathematical modeling. Key questions in human bioenergetics await these results, and our laboratory is currently undertaking these studies.

Adult↗
PubMed1984

Purification and properties of alpha-D-mannose:beta-1,2-N-acetylglucosaminyl-transferases and alpha-D-mannosidases from human adenocarcinoma.

Two specific N-acetylglucosaminyltransferases, alpha-1,3-mannoside:beta-2-N-acetylglucosaminyltransferase (transferase I) and alpha-1,6-mannoside:beta-2-N-acetylglucosaminyltransferase (transferase II), which catalyze the transfer of N-acetylglucosamine (GlcNAc) from uridine diphospho-GlcNAc to terminal branched alpha-mannosyl (Man) residues, were purified from liver metastases of human colon adenocarcinoma. Transferase I was assayed with Man alpha 1,6(Man alpha 1,3)Man alpha 1,6(Man alpha 1,3)Man beta 1,4GlcNAc beta 1, 4GlcNAc-Asn (Km 0.35 mM), and transferase II was assayed with Man alpha 1,6(GlcNAc beta 1,2Man alpha 1,3)Man beta 1,4GlcNAc beta 1,4-Glc-NAc-Asn (Km 1.0 mM), in which Asn is asparagine. The Km of transferase I for Man alpha 1,6(Man alpha 1,3)Man beta 1,4GlcNAc-beta 1,4)-(Fuc alpha 1,6)GlcNAc-Asn was 1 mM. The specificity of the interaction of transferase I with ovalbumin, ovomucoid, the modified heavy chain of porcine immunoglobulin G and glycopeptides prepared from these glycoproteins was examined by kinetic and structural analysis. The best macromolecular substrates for transferase I were ovalbumin devoid of terminal GlcNAc and some mannose, a solubilized preparation of the heavy chain of porcine immunoglobulin G, devoid of sialic acid, galactose, and terminal GlcNAc, and untreated ovomucoid. The apparent KmS were 45, 19, and 390 microM for ovalbumin, the modified heavy chain of immunoglobulin G, and untreated ovomucoid, respectively. The apparent Km of the enzyme for uridine diphospho-GlcNAc was not significantly influenced by the nature of the glycoprotein acceptor, and it varied between 14 and 20 microM for the different glycoproteins. The structures of the oligosaccharide chains in these glycoproteins which acted as acceptors for the purified enzyme were determined. A major glycopeptide product with the structure Man alpha 1,3(Man alpha 1,6)Man alpha 1,6(14C-GlcNAc beta 1,2Man-alpha 1,3)Man beta 1,4GlcNAc-beta 1,4-GlcNAc-Asn was isolated from both ovalbumin and ovomucoid following incubation with transferase I. The specificity of the enzyme for terminal branched mannosyl residues attached to a beta-linked mannose unit greatly restricts the action of this transferase to this juncture in the synthesis of complex-type oligosaccharide chains of N-asparagine-linked glycoproteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed1984

Structures of the oligosaccharide chains of two forms of alpha 1-acid glycoprotein purified from liver metastases of lung, colon, and breast tumors.

Two forms of alpha 1-acid glycoprotein with common immunological determinants and almost identical amino acid compositions but different amounts of carbohydrate were isolated from liver metastases of primary colon, lung, and breast tumors by extraction with perchloric acid, gel filtration on Sepharose CL-6B and Sephadex G-200, and affinity chromatography on concanavalin A:agarose and Ricinus communis agglutinin l:agarose. Both forms of the antigen yielded single bands which stained for protein and carbohydrate when examined by disc gel electrophoresis and immunodiffusion. The molecular weights of the two forms were 45,000 and 37,000 respectively. The larger form contained about five to six oligosaccharide chains, whereas the smaller form had only three to four chains. The composition and structures of the oligosaccharide chains in the two forms of this glycoprotein were very similar. Each contained di-, tri-, and tetraantennary complex-type oligosaccharide chains. The diantennary oligosaccharide chains caused both forms of alpha 1-acid glycoprotein to be retained by concanavalin A-agarose columns. The lower-molecular-weight form contained fewer chains and correspondingly fewer terminal galactosyl residues. This resulted in the separation of this species from the higher-molecular-weight form on columns containing R. communis agglutinin I. Three types of reduced oligosaccharides were released from the light and heavy forms of alpha 1-acid glycoprotein by treatment with alkaline borohydride or by hydrazinolysis. These chains were isolated by chromatography on concanavalin A:agarose and Bio-Gel P-6 columns. The arrangement and linkage of sugars in the purified oligosaccharides were determined by periodate oxidation, sequential hydrolysis with glycosidases, and methylation analysis. The major oligosaccharide chain, comprising 50 to 55% of the carbohydrate, had a triantennary structure as shown in the structure: (formula; see text) in which NeuNAc is N-acetylneuraminic acid, Gal is galactose, GlcNAc is N-acetylglucosamine, Man is mannose, GlcNAcol is N-acetylglucosaminitol, and Fuc is fucose. Tetraantennary chains comprised about 25 to 30% of the carbohydrate, and the additional outer chain was attached to the alpha 1,6-mannosyl residue through a beta 1,6-linked GlcNAc unit. The remaining 15 to 20% of the oligosaccharide chains had a diantennary structure. The extent of sialylation of these chains varied in samples isolated from tumors of the same histological type from different individuals. However, a relatively constant proportion of the three types of chains was present in different forms of the glycoprotein isolated from liver metastases.

Amino Acids↗
PubMed1982

Biochemical composition of muscle in normal and semistarved human subjects: relevance to anthropometric measurements.

Anthropometric methods aimed at assessing muscle size in undernourished subjects assume a constant proportionality between the mass (i.e., size) and composition (specifically protein-energy content) of this tissue. This assumption was examined in three autopsy groups: controls (n = 11, sudden traumatic death), early semistarvation (n = 6), acute preterminal disease), and chronic semistarvation (n = 34, severe weight loss over time). Results of semistarved groups were expressed relative to respective control value. Early semistarvation produced no detectable change in muscle mass, protein, or total energy content (per gram wet weight), although RNA and glycogen were -50 to -70% of control value (p less than 0.05). Chronic semistarvation caused muscle atrophy (-54.2%), but not all measured constituents were reduced to the same degree. The results were H2O--52.9%, collagen--46%, noncollagen proteins--65.3%, total lipids--40%, DNA--54.1%, RNA--81.7%, glycogen--90.3%, and total energy--59.6%. Muscle per unit mass in chronic semistarvation thus reflects relatively more H2O and less protein and energy when compared to normal tissue. About 85 to 95% of muscle protein-energy loss can be detected by anthropometric measurements of muscle size; the remaining 5 to 15% depletion of protein and energy is masked by muscle compositional changes. Proper interpretation of anthropometric data requires an understanding of these unmeasured but important compositional differences in normal and semistarved muscle.

Anthropometry↗
PubMed1981

Energy malabsorption: measurement and nutritional consequences.

Fecal energy (FE) loss was measured using bomb calorimetry in 30 patients; 14 had a history of malabsorption, while 16 had no history of intestinal dysfunction. Average digestibility (and range) of energy and FE loss were 73% (48 to 91%) and 493 kcal/day (177 to 927 kcal/day) in the group with malabsorption, compared to 96% (89 to 99%) and 74 kcal/day (8 to 146 kcal/day) in the group without malabsorption, respectively. Metabolizable energy supplied by the diet (intake kcal -- (fecal kcal + urinary kcal) was below the calculated daily energy requirement in five of seven patients with malabsorption; in three of these five subjects the combination of decreased energy intake and increased FE loss produced negative energy balance, while in the remaining two patients malabsorption alone caused negative energy balance. Inadequate metabolizable energy in these five patients was associated with weight loss and protein-energy malnutrition. The usual clinical laboratory tests applied to the study of malabsorption, including fecal fat, fecal nitrogen, and stool weight, were poor predictors of FE loss. These tests were also of limited value in assessing the effects of dietary modification on energy malabsorption. Contrastingly, bomb calorimetry provided a simple and accurate alternative in quantitatively assessing FE loss in the patient with malabsorption.

Calorimetry↗
PubMedDate not supplied

Human gradient-layer calorimeter: development of an accurate and practical instrument for clinical studies.

A whole body gradient-layer calorimeter was designed for thermophysiologic studies in hospitalized patients. The instrument was assembled in a room adjoining a metabolic ward. The patient lies recumbent on a stretcher which is wheeled into the calorimeter on tracks. Once inside, the patient's head extends through one wall into a clear plastic canopy. The canopy is partially open on one side and is the entry point for fresh air into this open-circuit system. Heat flux transducers in the calorimeter walls, a thermopile in the exit air stream, and a platemeter in conjunction with wet and dry bulb thermometers allow measurement of total, wet, and dry heat losses from the subject. All calorimeter output signals are routed to a microcomputer system which processes the data and provides real-time output of results. A mannequin heat source is used to calibrate the gradient layer. Testing with a variety of wet/dry heat sources indicate total, wet, and dry heat measurements are accurate to within 2-3%. A typical study of resting energy expenditure requires 1 hr, and protocols of up to 6 hr are well tolerated. The calorimeter has proven to be reliable, accurate, and easy to operate. These qualities, combined with good patient tolerance, make it ideal for metabolic studies.

Calorimetry↗
PubMedDate not supplied

Cytotoxic T lymphocyte epitopes shared between HIV-1, HIV-2, and SIV.

A peptide epitope from the gag protein of SIV and from HIV-1 is described which is presented by a cynomolgus macaque MHC molecule and with HLA B14. Comparisons were drawn between recognition of this peptide and that of a second peptide defined in SIV and HIV-2 which has been reported to be presented by the rhesus macaque molecule MaMuA01 and HLA B53 respectively.

Amino Acid Sequence↗