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Biomedical subjects

M K Robinson

Publications and source records attributed to M K Robinson.

At least 91 records · Page 5Linked to original sources
PubMed1993

Comparison of the Bio Image Visage 2000 and the GELLAB-II two-dimensional electrophoresis image analysis systems.

To compare the Visage 2000 analysis system (Bio Image, Ann Arbor, MI, USA) with the GELLAB-II analysis system (National Cancer Institute, Frederick, MD, USA), we used each to perform image analysis of the same 29 silver-stained two-dimensional electrophoresis (2DE) gel image files from a study of urinary proteins in metal recovery plant workers who had confirmed body burdens of cadmium. Visage, aided by interactive analysis, detected an average of 890 +/- 177.6 spots per gel, or a total of 25,800 spots, whereas GELLAB-II detected 1971 +/- 198.5 spots per gel, or a total of 57,160 (a 222% increase over the Visage system), without operator intervention. Visage automatically quantified 52.5% (13,556) of the spots; 47.2% (12,173), consisting mostly of larger spots, had to be quantified interactively with an image editor, and 0.3% (71) were not quantified. GELLAB-II automatically quantified all detected spots. After we interactively assigned the maximum allowed number of landmarks (30 for Visage and 52 for GELLAB-II), we found that Visage matched 657 +/- 211.2 spots per gel, and GELLAB-II matched all detected spots and also extrapolated an average of 1269 virtual spots per gel. Plots of densities from the two systems on selected spots showed excellent agreement, and both systems showed high correlation between their measurements of the beta-2-microglobulin spot densities and an independent radioimmunoassay quantification of the original urine samples. By comparing the regression of the densities of all spots with urinary cadmium (UCD) levels, we found that several of the same detected spots from each system were highly correlated. The densities of four acidic proteins with relative molecular weights of approximately 112,000 Da (as quantified by GELLAB-II but not by Visage) were highly correlated with UCD concentrations. These proteins are new candidate biomarkers of cadmium toxicity. We compared the estimated labor costs of using each system to analyse a hypothetical 20-sample (60 gels) 2DE study and found that GELLAB-II was six times less expensive to use than Visage, primarily because of the operator time required to do interactive error correction with the Visage system.

Cadmium↗
PubMed1993

Effects of the Patient Self-Determination Act on patient knowledge and behavior.

BACKGROUND: In effect since 1991, the Patient Self-Determination Act (PSDA) requires that institutions receiving government insurance payments document that they have informed patients of their right to decide on life-preserving measures. Implementing the PSDA should make discussion of advance directives a routine part of acute care hospital admissions. Yet the proportion of those actually completing advance directives such as living wills remains relatively small. METHODS: A telephone survey questionnaire was administered to patients who were hospitalized before and after the implementation of the PSDA. Survey questions probed patient knowledge about living wills and behavior toward obtaining living wills. RESULTS: Patient knowledge about advance medical directives correlated positively with race (white), income (> or = $10K), and level of education (high school or more). Moreover, a significantly greater number of patients hospitalized after implementation of the PSDA knew about living wills than the number of those hospitalized before the Act's implementation. However, actually obtaining a living will correlated positively with age (> 36 years) alone, and implementation of the PSDA was not related to the number of patients who obtained a living will. CONCLUSIONS: Although the study results show that the measures the hospital in the study used to meet PSDA requirements increased patient awareness of living wills, they failed to increase the number of patients who act on this awareness. This finding indicates that simply informing patients about their right of self-determination is insufficient to meet the intended goals of the legislation.

Adult↗
PubMed1993

Exploratory data analysis in two-dimensional electrophoresis.

The use of computerized matching of proteins in the analysis of multiple two-dimensional electrophoresis (2DE) gels creates volumes of data that are readily accessible for exploratory analysis. When these data are used in health-effects studies or in studies to identify factors associated with particular diseases, hundreds or even thousands of hypotheses can be tested. Interpreting so many hypothesis tests requires some preliminary statistical evaluations of the data. In addition, prior to the preliminary statistical evaluations and subsequent hypothesis tests, accurate protein quantification and correct protein matching must be verified. In this report we present an approach used at the Centers for Disease Control to address these issues. This approach consists of a randomized experimental design incorporating replicate gels for each specimen, gel image analysis, protein matching, editing, Boolean unions of all gels to obtain correspondences and contradictions of match identification numbers, resolution of correspondences and contradictions, statistical tests to identify outliers, and finally an assessment of statistical and practical significance to focus attention on the proteins most likely to be associated with the effects under study. We illustrate our approach with data from an exploratory exposure-response study.

Blood Protein Electrophoresis↗
PubMed1993

Quantitative two-dimensional electrophoretic detection of possible urinary protein biomarkers of occupational exposure to cadmium.

To search for new urinary protein biomarkers of cadmium toxicity, we used quantitative two-dimensional electrophoresis (2DE) and analysed urine samples from 18 male cadmium recovery plant employees whose mean age was 47 +/- 15.6 years (+/- 1 SD) and whose urine cadmium levels ranged from 0.14 microgram l-1 to 20.4 micrograms l-1 (0.06-37.1 micrograms g-1 creatinine). Image analysis of the silver-stained gels yielded intensity (concentration) values for a mean number, per person, of 825 +/- 184 urinary proteins (spots) and found 596 +/- 218 matched proteins (the same proteins in two or more gels) per person. Total urinary protein and the sum of all spot intensities were positively correlated (P = 0.0447 and P = 0.0616, respectively) with urinary cadmium (UCD), as measured by atomic absorption spectroscopy. The combined sum of the intensities of all acidic proteins with a relative molecular weight (M(r)) below 40 kDa was correlated with UCD (P = 0.0461), revealing a low M(r), acidic proteinuria as UCD increased. Multiple hypothesis testing by regression analysis of the intensities of matched proteins with UCD revealed 14 unidentified proteins that were considered candidates for biomarkers of cadmium exposure. The best two candidate proteins--those having M(r)s of less than 13.9 kDa and relative glyceraldehyde-3-phosphate dehydrogenase (G3PDHr) coordinates of -19.7 and -27.2--were excellently resolved in the 2DE gels, and their intensities increased by 323% and 857%, respectively, over the UCD range that was tested. Two other proteins with M(r)s of 23.9 kDa and 29.2 kDa and with acidic net charges were not as well resolved. Six very acidic proteins, with M(r)s ranging from 88.8 to 90.7 kDa and with intensities highly correlated with UCD, appeared to be related and were resolved as a 'charge train' (a group of related proteins, or isoforms, differing only by small changes in net charge). Four proteins appeared to increase only when the UCD concentration was above a threshold of 16 micrograms l-1.

Adult↗
PubMed1992

Comparison of L-selectin and E-selectin ligand specificities: the L-selectin can bind the E-selectin ligands sialyl Le(x) and sialyl Le(a).

The L- and E-selectins are leukocyte and endothelial cell surface molecules which mediate leukocyte-endothelial cell adhesion by interacting with carbohydrate ligands. In the present study we find that L-selectin, like E-selectin, can interact with synthetic neoglycoproteins containing Sialyl Le(x) (Neu5Ac alpha 2-3Gal beta 1-4[Fuc alpha 1-3]GlcNAc beta-R), or Sialyl Le(a) (Neu5Ac-alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta-R). Additionally, both the E-selectin and L-selectin can bind the peripheral lymph node addressin, a high endothelial venule ligand for L-selectin. Despite overlapping interactions, the L- and E-selectins discriminate between their native ligands. The peripheral lymph node addressin is a preferential ligand for L-selectin; and furthermore, L-selectin expressing cells do not interact detectably with the cutaneous lymphocyte antigen, a native glycoprotein ligand for E-selectin found on a subset of lymphocytes associated with the skin.

Animals↗
PubMed1992

Antibody against the Leu-CAM beta-chain (CD18) promotes both LFA-1- and CR3-dependent adhesion events.

The Leukocytic cell-adhesion molecule (beta 2 integrin) family of adhesion molecules play a key role in the intercellular adhesive interactions necessary for normal immune cell function. In this study, we report an antibody that recognizes an epitope on the Leukocytic cell-adhesion molecule common beta-chain (CD18) and promotes both lymphocyte function-associated Ag-1- and CR3-dependent adhesion events. The antibody recognizes a temperature-sensitive epitope that is not dependent on the presence of divalent cations. It is proposed that antibody binding promotes a conformational change in both lymphocyte function-associated Ag-1 and CR3, which may mimic a natural activation mechanism, resulting in increased cellular adhesion.

Antibodies, Monoclonal↗
PubMed1992

Neutrophil adhesion: a point for therapeutic intervention?

It has become increasingly clear over the last 20 years that the potential exists to modulate inflammatory responses with compounds that interfere with intercellular adhesion. This review highlights the adhesion interactions that occur during neutrophil extravasation and indicates some of the possible ways of disrupting these interactions.

Animals↗
PubMed1992

Glutamine preserves liver glutathione after lethal hepatic injury.

Glutathione (GSH) is a major antioxidant that protects tissues from free radical injury. Glutamine augments host defenses and may be important in GSH synthesis. Acetaminophen toxicity causes hepatic GSH depletion and hepatic necrosis. The authors hypothesized that glutamine-supplemented nutrition would enhance liver GSH stores and diminish hepatic injury and death after acetaminophen overdose. Wistar rats received either a standard total parenteral nutrition (TPN) solution (STD) or an isocaloric, isonitrogenous glutamine-supplemented solution (GLN). On the 5th day of feeding, animals were given acetaminophen (400 mg/kg intraperitoneally) and then killed at various time points. Standard TPN solution animals had a rapid depletion of hepatic glutathione, whereas GLN animals were resistant to this drop and rapidly repleted hepatic GSH stores. Glutamine-supplemented animals maintained higher plasma glutamine concentrations, had lesser elevations in hepatic enzymes, and sustained significantly fewer complications compared with STD animals. The authors conclude that glutamine-supplemented nutrition preserves hepatic glutathione, protects the liver, and improves survival during acetaminophen toxicity. Glutamine may augment host defenses by enhancing antioxidant protection.

Acetaminophen↗
PubMed1992

Hypercholesterolemia: case finding in family practice.

The recommendations of the expert panel of the National Cholesterol Education Program (NCEP) have been endorsed by national medical organizations as standards for the detection and treatment of hypercholesterolemia, yet information on how these recommendations are being followed in primary care settings is limited. This study was done to determine how family physicians in four primary care clinics associated with a teaching hospital in a large southern city follow the NCEP guidelines. Of the total patient sample (N = 817), about 60% had at least one total serum cholesterol measurement. Patients in the younger age groups were less likely to have a cholesterol determination than older patients. Of those in the "self-pay" category only 33% had a cholesterol determination. Variability by clinic and provider type was also noted, with physician assistants showing the highest compliance with screening guidelines (75%), whereas only 43% of patients seen by family practice residents had a cholesterol measurement. Of patients who should have had a lipoprotein analysis, based on total serum cholesterol and risk factors, only 23% actually had a lipid profile. Our study and other similar ones point out that case finding varies considerably and that efforts to improve case finding need to continue.

Adult↗
PubMed1992

Retinal vein occlusion.

Retinal vein occlusion is a common form of retinal vascular disease, especially in middle-aged and older individuals. The diagnosis is based on the funduscopic finding of retinal vein dilatation in association with retinal hemorrhages and cotton-wool spots. The pathology can involve the entire venous system or can be limited to a branch of the central retinal vein. Retinal vein occlusion can be distinguished clinically from diabetic retinopathy and other retinal diseases. Treatment for the acute phase of retinal vein occlusion has been disappointing. However, some late complications, such as persistent macular edema and neovascularization of the iris and retina, respond well to retinal photocoagulation. The family physician has an important role in detecting and controlling risk factors for retinal vein occlusion, including hypertension, diabetes mellitus and hyperviscosity syndromes.

Adult↗
PubMed1992

Glutathione deficiency increases organ dysfunction after hemorrhagic shock.

BACKGROUND: Reactive oxygen metabolites contribute to tissue destruction in a wide variety of diseases. Glutathione, a potent endogenous antioxidant, neutralizes the destructive potential of free radicals, but this tripeptide may be depleted during illness. We hypothesized that glutathione deficiency would amplify organ dysfunction after shock in rats. METHODS: Rats received either diethyl maleate to deplete tissue glutathione or a control solution intraperitoneally. The animals were subsequently bled to and maintained at a mean arterial pressure of 40 mm Hg for 30 minutes and then fully resuscitated. Sham animals underwent blood pressure monitoring only. Tissue glutathione, liver and renal function tests, organ bacterial content, and mortality rates were determined 4 and 24 hours after shock. RESULTS: Normal rats subjected to shock and sham animals had similar laboratory chemistry results, organ culture results, and mortality rates. However, glutathione-depleted animals subjected to shock had elevated liver and renal function tests, increased organ bacteria, and a dramatic increase in mortality rates compared with control shock and sham animals. CONCLUSIONS: We conclude that glutathione deficiency predisposes animals to organ failure and death after an otherwise nonlethal period of hypotension. Because glutathione deficiency is associated with severe injury and sepsis, treatment strategies that maintain glutathione stores may decrease the incidence of multisystem organ failure.

Animals↗
PubMed1991

The cutaneous lymphocyte antigen is a skin lymphocyte homing receptor for the vascular lectin endothelial cell-leukocyte adhesion molecule 1.

A skin-associated population of memory T lymphocytes, defined by expression of the cutaneous lymphocyte antigen (CLA), binds selectively and avidly to the vascular lectin endothelial cell-leukocyte adhesion molecule 1 (ELAM-1), an interaction that may be involved in targeting of CLA+ T cells to cutaneous sites of chronic inflammation. Here we present evidence that CLA itself is the (or a) lymphocyte homing receptor for ELAM-1. Antigen isolated with anti-CLA monoclonal antibody HECA-452 from human tonsillar lysates avidly binds ELAM-1 transfected mouse cells. Anti-CLA antibody blocks T lymphocyte binding to ELAM-1 transfectants. HECA-452 and ELAM-1 binding to lymphocytes or to isolated tonsillar HECA-452 antigen is abrogated by neuraminidase treatment implying a prominent role for sialic acid in CLA structure and function. The dominant form of CLA on T cells is immunologically distinct from the major neutrophil ELAM-1 ligand, the sialyl Lewis x (sLex) antigen (NeuAc alpha 2-3Gal beta 1-4[Fuc alpha 1-3]GlcNAc), which is absent, weakly expressed, or masked on T cells. However, neuraminidase treatment of CLA+ T cells, but not of CLA- T cells, reveals Lewis x (CD15) structures. In combination with the known requirement for terminal NeuAc alpha 2-3Gal and fucose residues attached to N-acetylglucosamine for ELAM-1 and HECA-452 binding, this finding suggests that CLA may comprise an additionally sialylated or otherwise modified form of sLex. The identification of a lymphocyte homing receptor for skin may permit novel approaches to the diagnosis and therapy of cutaneous and inflammatory disorders.

Animals↗
PubMed1991

A carbohydrate domain common to both sialyl Le(a) and sialyl Le(X) is recognized by the endothelial cell leukocyte adhesion molecule ELAM-1.

The specificity of endothelial cell leukocyte adhesion molecule-1, ELAM-1, for binding to a panel of carbohydrate structures was determined by a sensitive cell binding assay with immobilized synthetic glycoconjugates. ELAM-1 cDNA transfectants were found to bind Sialyl Lea (sialylated lacto-N-fucopentaose II) or sialylated Lewis a antigen (NeuAc alpha 2-3Gal beta 1-3(Fuc alpha 1-4)GlcNAc), as well as or slightly better than Sialyl Lex (sialylated lacto-N-fucopentaose III) or sialylated Lewis X antigen (NeuAc alpha 2-3 Gal beta 1-4(Fuc alpha 1-3)GlcNAc). A monoclonal antibody, HECA-452, which has been identified recently as recognizing ELAM-1 ligands in addition to those containing Sialyl Lex, was also found to bind both Sialyl Lex and Sialyl Lea. Hard sphere exo-anomeric (HSEA) calculations were performed on these two hexasaccharides. The conformations indicate that Sialyl Lea and Sialyl Lex show a high degree of similarity in both the nonreducing and reducing termini. As Lea and Lex show much weaker reactivity, the determinants recognized by ELAM-1 and HECA-452 probably involve neuraminic acid and fucose residues which on one face of both Sialyl Lex and Sialyl Lea can be similarly positioned. The finding that Sialyl Lea is a potent ligand for ELAM-1 is important, as circulating Sialyl Lea and Sialyl Lex containing mucins which are elevated in the serum of many cancer patients may block leukocyte interactions with ELAM-1 and may contribute to the pathological immunodepression observed in these patients.

Animals↗
PubMed1991

Evaluation of the primary skin irritation and allergic contact sensitization potential of transdermal triprolidine.

A transdermal patch for the OTC antihistamine, triprolidine (TP), might provide benefits in terms of increased efficacy and reduced sedative side effects. However, concerns over potential irritant or allergic contact sensitization (ACS) skin reactions necessitated through skin toxicity testing before and during initial clinical development. Initial effort was expended on development of a binary vehicle delivery system comprised of TP in 0.5% oleic acid (OA) in propylene glycol (PG). Rabbit skin irritation and Buehler guinea pig skin sensitization testing indicated that this TP/OA/PG formula had both skin irritation and ACS potential. Both tests underestimated, to some degree, the skin toxicities observed in later clinical testing. In clinical tests, skin irritation was due mainly to the OA/PG vehicle, but was enhanced in the presence of high TP concentrations. Of 26 subjects enrolled in a rising dose clinical pharmacokinetics study, one subject exposed twice to TP/OA/PG presented with delayed skin reactions suggestive of ACS. Positive diagnostic patch test results for this subject and four out of five other twice-exposed study subjects suggested that the TP/OA/PG formula had a very high ACS potential. Subsequent predictive clinical patch testing was conducted with a buffered aqueous TP formula which provided in vitro skin penetration of the drug equivalent to the TP/OA/PG formula. These clinical studies demonstrated that TP itself had no significant irritation potential but still induced ACS reactions in a high proportion of test subjects. The incidence of adverse skin reactions to TP was considered to be too high relative to the degree of improved therapeutic benefit of this delivery form. On this basis, all technology development effort was discontinued.

Administration, Cutaneous↗
PubMed1991

The human peripheral lymph node vascular addressin is a ligand for LECAM-1, the peripheral lymph node homing receptor.

The trafficking of lymphocytes from the blood and into lymphoid organs is controlled by tissue-selective lymphocyte interactions with specialized endothelial cells lining post capillary venules, in particular the high endothelial venules (HEV) found in lymphoid tissues and sites of chronic inflammation. Lymphocyte interactions with HEV are mediated in part by lymphocyte homing receptors and tissue-specific HEV determinants, the vascular addressins. A peripheral lymph node addressin (PNAd) has been detected immunohistologically in mouse and man by monoclonal antibody MECA-79, which inhibits lymphocyte homing to lymph nodes and lymphocyte binding to lymph node and tonsillar HEV. The human MECA-79 antigen, PNAd, is molecularly distinct from the 65-kD mucosal vascular addressin. The most abundant iodinated species by SDS-PAGE is 105 kD. When affinity isolated and immobilized on glass slides, MECA-79 immunoisolated material binds human and mouse lymphocytes avidly in a calcium dependent manner. Binding is blocked by mAb MECA-79, by antibodies against mouse or human LECAM-1 (the peripheral lymph node homing receptor, the MEL-14 antigen, LAM-1), and by treatment of PNAd with neuraminidase. Expression of LECAM-1 cDNA confers PNAd binding ability on a transfected B cell line. We conclude that LECAM-1 mediates lymphocyte binding to PNAd, an interaction that involves the lectin activity of LECAM-1 and carbohydrate determinants on the addressin.

Antigens, Surface↗
PubMed1991

Factors affecting inorganic mercury transport and toxicity in the isolated perfused proximal tubule.

The effects of cysteine (80 microM), glutathione (80 microM), rabbit albumin (100 microM), and an ultrafiltrate of rabbit plasma on the toxicity and transport of inorganic mercury (Hg2+; 18.4 microM) in isolated perfused S1, S2, and S3 segments of the renal proximal tubule from the rabbit were studied. Cellular and tubular injuries were assessed qualitatively by light microscopy observations and quantitatively by the tubular leak of the volume marker 3H-glucose. The lumen-to-bath transport of inorganic mercury was assessed by measuring both the rate of disappearance of inorganic mercury from the luminal fluid and the rate of appearance of inorganic mercury in the bath. When glutathione was added to the perfusate containing the inorganic mercury, no signs of epithelial cell necrosis or injury were detected in any of the three segments of the proximal tubule. There was also an absence of or a decrease in cellular injury in the epithelium of the same tubular segments when either cysteine or the ultrafiltrate was present in the perfusate. However, when rabbit albumin and inorganic mercury were present in the perfusate, severe degenerative and necrotic changes occurred very rapidly in the epithelium of all three segments of the proximal tubule. In almost every instance where glutathione, cysteine, or the plasma ultrafiltrate were present in the perfusate, the disappearance flux of inorganic mercury from the tubular lumen into the tubular epithelium was lowered. It was concluded that glutathione, cysteine, and the ultrafiltrate of rabbit plasma provide isolated perfused S1, S2, and S3 segments of the proximal tubule varying degrees of protection from the toxic effects of inorganic mercury. This protection appears to be related to a decrease in the movement of inorganic mercury across the luminal membrane of the tubular epithelial cells.

Albumins↗
PubMed1991

Increased number of dendritic cells in draining lymph nodes accompanies the generation of contact photosensitivity.

Draining lymph node cells isolated from mice 48 h after topical exposure to tetrachlorosalicylanilide (TCSA) + UVA radiation (TCSA + UVA) demonstrated a two-fivefold increase in the number of dendritic cells (DC) compared with control mice treated with vehicle + UVA. The increase in number of DC was both time and dose dependent, with the peak DC accumulation occurring at 48 h post application and at a TCSA dose of 1.0%. Photospecificity was evident in that mice irradiated prior to treatment with TCSA (UVA/TCSA) demonstrated no significant increase in DC accumulation. The accumulation of DC was followed by a significant increase in total lymph node cellularity. An in situ 3H-thymidine incorporation assay showed a significant increase in proliferative activity of cells isolated from the draining lymph nodes of mice treated with TCSA + UVA as compared to naive, vehicle, or UVA/TCSA-treated mice. Dendritic cells isolated from mice treated 24 h earlier with TCSA + UVA, but not those from naive mice or mice treated with UVA/TCSA, were capable of TCSA-specific antigen presentation. Responder lymphocytes from untreated mice or mice photosensitized with musk ambrette showed a much lower response to DC isolated from TCSA + UVA-treated mice, demonstrating the specificity of the reaction. DC-depleted lymph node cells were unable to stimulate this blastogenesis response. These results suggest that application and photoactivation of TCSA induces cellular and functional changes in the lymph node DC indicative of their involvement in the induction phase of a contact photoallergic reaction.

Allergens↗