Search PubMed⌕ Search

Biomedical subjects

T M Phillips

Publications and source records attributed to T M Phillips.

At least 73 records · Page 4Linked to original sources
PubMed1989

Immune complex assays: diagnostic and clinical application.

The presence of circulating immune complexes have been described in many different human disease states but the significance of their presence has always been a subject for debate. Improvements in the methods of detecting immune complexes have demonstrated a wide degree of heterogeneity, which accounts for the difficulty in obtaining accurate and reproducible measurements, even in the same individual. Techniques for isolating individual complexes, characterizing their pathophysiological properties, and biochemically analyzing the nature of the complexed antigen are now being used to provide data that is helping to clarify the role of immune complexes in the pathogenesis of disease. In addition, such studies are also providing data which is proving that immune complexes have a potential role in immune regulation.

Antigen-Antibody Complex↗
PubMed1989

Adenosine nucleotide utilization in subtotally nephrectomized rabbits.

Two- to three-kilogram albino rabbits were subtotally nephrectomized and compared with sham-operated normal rabbits for the muscle content of adenosine mono (AMP)-, di (ADP)- and triphosphate (ATP) and inosine monophosphate (IMP) before and after exercise. Analysis of snap-frozen, lyophilized soleus muscle showed lower levels of AMP, ATP and total adenosine nucleotide (TAN) (p less than 0.01) and ATP/ADP (p less than 0.02) in the subtotally nephrectomized animals. IMP levels following exercise were higher in the experimental animals. Muscle adenosine nucleotide concentrations in the experimental animals were significantly different for normals, thus suggesting that minimal azotemia could adversely affect muscle function in these animals.

Adenine Nucleotides↗
PubMed1988

High-performance affinity isolation of lymphocyte membrane receptors on biotinylated antigen and avidin-coated beads.

Isolation of lymphocyte membrane receptors can be achieved by high-performance liquid chromatography using immobilized streptavidin as the ligand and biotinylated antigen. Activated lymphocytes were allowed to react with biotin-labelled antigen prior to harvesting. The cells were disrupted and their membranes solubilized before passing the suspension through the avidin affinity column. The biotinylated antigen acted as an efficient receptor probe, which helped to maintain the integrity of the receptor during the isolation procedure. The biotin also acted as the substrate that attaches to the immobilized avidin. Recovery of the bound receptor was achieved by dissociation of the receptor from the antigen and recovery of the receptor in the effluent during the elution phase of the separation.

Avidin↗
PubMed1988

Isolation of specific lymphocyte receptors by high-performance immunoaffinity chromatography.

Isolation of antigen-specific lymphocyte receptors can be achieved by high-performance immunoaffinity chromatography, using immobilized monoclonal antibodies directed against the antigen. Primed lymphocytes are allowed to react with their target antigen prior to disruption and membrane solubilization. The bound antigen acts both as a preservative for the receptor and as a ligand on which the immobilized antibody captures the antigen-receptor complex. Dissociation of the antigen-antibody complex also releases the antigen from the receptor, and both antigen and receptor can be separated and recovered for further study.

Animals↗
PubMed1988

Use of avidin-coated glass beads as a support for high-performance immunoaffinity chromatography.

Immunoaffinity chromatography, using immobilized antibodies, is a useful technique for the specific isolation and purification of biological materials. We have developed an avidin-coated glass bead which can easily immobilize and retain under adverse conditions, such as acid elution, any antibody which is covalently labelled with biotin. The physical strength of the bead, together with the expanding repertoire of commercially available biotinylated monoclonal antibodies makes this support ideal for both medium- and high-performance immunoaffinity chromatography.

Antibodies, Monoclonal↗
PubMed1988

Immunoaffinity isolation of the Lewis blood group antigens.

Extraction, followed by immunoaffinity chromatography on a column of immobilized antibodies is described for the isolation of the Lewis blood group antigens. These affinity-isolated antigens are suitable in organ transplant immunology laboratories for screening potential donors and recipients for mismatch at the Lewis antigen loci.

Antibody Specificity↗
PubMed1988

Zinc balance in combined zinc deficiency and uremia.

In order to evaluate whether the hypozincemia associated with chronic renal failure represents true negative zinc balance, male Lewis rats were randomized and pair-fed zinc replete (+Zn) or deplete (-Zn) diets. Subsequently, each animal underwent one- and two-thirds nephrectomy, or a sham operation. Complete balances for zinc, calcium, and magnesium were determined weekly before and after nephrectomy. At sacrifice, -Zn animals had significantly lower (P less than 0.005) plasma zinc levels compared to controls. Nephrectomized (N) animals had significantly elevated plasma creatinine (P less than 0.005), diminished creatinine clearances (P less than 0.005), and increased urinary flows (P less than 0.005) and protein excretion (P less than 0.01) compared to sham-operated (S) controls. Zinc nutritional status had no effect on these parameters in animals with comparable renal function. -Zn/N animals had consistently significantly elevated (P less than 0.005) urinary zinc excretion compared with -Zn/S with similar plasma zinc concentrations. Urinary zinc excretion correlated with urinary flow (r = 0.739, P less than 0.005), urinary protein (r = 0.635, P less than 0.01) and urinary calcium excretion (r = 0.855, P less than 0.005) in -Zn groups. -Zn/N rats had a significantly larger fecal zinc excretion for the first week post-nephrectomy, compared to -Zn/N controls (P less than 0.005). This resulted in negative zinc balance in -Zn/N animals, compared to their pre-nephrectomy balance (P less than 0.05) or to -Zn/S controls for the first (P less than 0.005) and second (P less than 0.05) weeks. -Zn/N rats had lower (P less than 0.02) hepatic zinc concentrations compared to the -Zn/S group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

High-performance immunoaffinity chromatographic detection of immunoregulatory anti-idiotypic antibodies in cancer patients receiving immunotherapy.

Anti-idiotypic antibodies are regulatory antibodies responsible for the shutdown of active immune responses against growing tumor cells. In an attempt to study these antibodies, a technique for isolating specific anti-idiotypic antibodies by immunoaffinity chromatography was devised. Human anti-tumor antibodies were isolated by affinity absorption to fixed autologous tumor cells. These antibodies were biotinylated, immobilized on streptavidin-coated beads, and used as a ligand to isolate reactive anti-idiotypes from the plasma of patients during periods when immune reactivity against their tumors could not be detected. The isolated anti-idiotypes demonstrated the ability to react with the original antibodies and to inhibit their binding to autologous tumor cells. Thus functional anti-idiotypic antibodies can be isolated by immunoaffinity chromatography with the original idiotype as the ligand. This technique can be used to monitor regulatory antibodies in cancer patients receiving immunotherapy.

Antibodies, Anti-Idiotypic↗
PubMed1987

Regional variation in the levels of transferrin in the CNS of normal and myelin-deficient rats.

Transferrin (Tf), the iron mobilization protein, is synthesized mainly in the liver. Recently, both Tf and a mRNA for Tf have been demonstrated in oligodendrocytes in the rat brain. The present study used a biochemical assay for determining the levels of Tf in various brain regions of normal rats compared with the level of those obtained from rats with a genetic mutation characterized by an almost complete failure to develop myelin. In myelin-deficient (md) rats, no Tf-positive oligodendrocytes were seen immunohistochemically in the gray or white matter of the CNS. Quantitatively, levels of Tf throughout the CNS of the md rat were decreased to approximately 5% of the normal values despite a normal hepatic synthetic rate. In the normal rat brain, the cerebellum contained the highest concentration of Tf, followed by the pons, the cerebral cortex, and the caudate-putamen, with the latter two sites being similar. Regional variation in the amount of Tf was in general agreement with published reports on the variation of iron and Tf receptor levels in the CNS. Immunohistochemical examination with antiserum to galactocerebroside (a myelin-specific lipid) was used for extending biochemical reports that glycolipid-synthesizing enzymes are deficient in md rats. No immunostaining in the md rat was observed following immunoreaction for galactocerebroside, whereas white matter oligodendrocytes were intensely marked in the normal rat. Robust astrogliosis was present in both the gray and white matter of the md rats. It is not known at present whether the ability to accumulate Tf is necessary for oligodendrocytic survival or if Tf accumulation is more directly related to myelinogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Temporal synthesis and presentation of antigens by cultured B16 melanoma cells.

Previous studies have demonstrated the presence of two distinct antigens, B700 and B50, which are unique to murine melanoma. One of these, B700 has been studied in detail, and is present on 5 different murine melanomas; it can function as a transplantation antigen in at least 3 of them (B16, JB/RH and K1735). The synthesis and presentation of these antigens has been studied as a function of cell culture conditions. Direct immunofluorescence studies of cells in serial culture indicate that the expression of B700 and B50 antigens at the cell surface and in the cytoplasm increases as a function of time in culture, over 1-5 days. By day 5, when the cells are confluent, all cells show some degree of antibody binding. Parallel 35S-methionine pulse chase labeling experiments show that incorporation into Triton soluble proteins, and Triton insoluble SDS soluble proteins, increases to a peak at 3.5 days after subculturing, then decreases as the cells reach confluence. Incorporation into proteins shed into the culture supernatant continued throughout the time course of cell growth to confluence. However, as the cells become confluent, total protein synthesis shifts towards greater production of the antigens (both cellular and shed). The sum of the results suggest that tumor growth may succeed in vivo by the wholesale production of "decoy" antigens.

Animals↗
PubMed1986

Characterization of the fertilization antigen 1 for the development of a contraceptive vaccine.

A fertilization antigen, FA-1, was purified from either deoxycholate- or lithium diiodosalicylate-solubilized murine testes by immunoaffinity chromatography using a monoclonal antibody, MA-24, which inhibited fertilization in vitro. The FA-1 was recovered at high (11.4) or low (2.8) pH using stepwise elution procedures of the deoxycholate or lithium diiodosalicylate extracts, respectively. Both of these fractions showed a single band of 47 kDa when analyzed by NaDodSO4/PAGE and silver staining. Following removal of the detergent and extensive dialysis at pH 5.8 or treatment with 0.15 M NaCl, even in the presence of detergent, a monomer of 23 kDa was detected. Two-dimensional PAGE of FA-1 showed, four or five polypeptides in the 47-kDa or 23-kDa range. The dialyzed FA-1 contained a major 23-kDa and a minor 48-kDa band when separated on both sucrose and cesium chloride gradients. High performance size-exclusion chromatography showed a major peak at 23 kDa and a minor peak at 50 kDa. Further analysis of the 23-kDa peak by reverse-phase chromatography resolved the antigen into three peaks, which gave similar two-dimensional gel patterns as the native FA-1. Lectin affinity chromatography on a lens culinaris column demonstrated that a part of the antigen was bound to the lectin while the rest was not. The FA-1 revealed a positive reaction with periodic-Schiff reagent and contained glucose and mannose, which together constituted 18.8% of the total antigen mass. Amino acid analysis showed a high percentage of aspartic acid, glutamic acid, serine, and glycine. As a single injection of MA-24 significantly reduced fertilization rates in vivo, the purified FA-1 is an attractive candidate for the development of contraceptive vaccine.

Amino Acids↗