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Biomedical subjects

S R Lee

Publications and source records attributed to S R Lee.

At least 91 records · Page 5Linked to original sources
PubMed1988

Serial studies of the IgG subclass and functional affinity of DNA antibodies in systemic lupus erythematosus.

The functional affinity and IgG subclass of antibodies to ss and dsDNA were measured by ELISA in five serial samples from 41 patients with systemic lupus erythematosus (SLE) who were divided into relatively homogeneous disease subgroups. Anti-dsDNA antibodies were restricted to IgG1 and IgG3 in renal disease and levels increased with disease severity. Functional affinity of IgG1 and IgG3 anti-dsDNA fell in patients with severe renal disease, suggesting that the high affinity antibody population lost from the serum was localizing in the kidneys. IgG2 anti-dsDNA were found in patients with joint and skin disease alone and in the thrombotic/spontaneous abortion subgroup. IgG2 antibody levels did not correlate with disease severity but did correlate with the presence of antibodies to Klebsiella K30 and may have represented a cross-reactive antibody population.

Antibodies, Antinuclear↗
PubMed1987

Quantitative immunochromatographic analysis: theory and application to theophylline immunoassay.

The development of an immunochromatographic technique suitable for rapid analysis of biological fluids is described. Quasi-one-dimensional antibody lattices specific for theophylline were constructed by packing Sepharose beads conjugated with specific antibody into specially designed narrow capillary tubes. The design of these capillary columns was such that they would subtract a preset threshold quantity of antigen (label and analyte) from the total amount presented. Labeled antigen, which appeared in the flowthrough, could then be used to precisely quantitate the analyte present. The ideal format would permit very precise subtraction of 100% of the available antigen up to the threshold amount and none of the remainder. The microcolumn described here comes close to this ideal behavior through the attainment of very high ratios of bound/free antigen. The elevated bound/free ratio could be explained by theoretical analysis of the effect on equilibria of the high antibody concentration in this quasi-one-dimensional system. Lattices containing anti-theophylline antibodies were used to develop a competitive enzyme immunoassay for theophylline which demonstrated a dose-response that was closely similar to that predicted by theoretical treatment. The entire assay procedure was performed in less than 30 min and demonstrated a sensitivity limit of approximately 20 ng/ml. Preliminary studies on clinical serum samples suggest that this assay has potential for the routine analysis of biological fluids.

Chromatography, Affinity↗
PubMed1987

Magnesium-induced catharsis in chicks.

High magnesium (Mg) diets induce diarrhea in chicks. Addition of 0.3, 0.5 or 0.9% Mg (as MgO) to a corn-soy basal diet caused a dose-related lower gut passage time (GPT) (the first appearance of colored markers from feed in excreta), with the threshold for catharsis being approximately the 0.3% addition. Supplementation of the high Mg diets with a water-absorbent clay did not change the chicks' GPT. The beta-adrenergic blocking agent propranolol (1.68 mg/kg body wt) or the alpha-adrenergic blocking agent phenoxybenzamine (0.28 mg/kg body wt) did not effect the GPT of chicks fed high Mg diets. However, both the muscarinic blocker methscopolamine (0.12 mg/kg body wt) and the serotonergic blocker methysergide (0.2 mg/kg body wt) resulted in a higher GPT of chicks fed high Mg diets compared to corn-soy fed control chicks. Analysis of the osmotic load of excreta or intestinal contents of high Mg-fed chicks showed no differences from osmotic loads of control-fed chicks. When the osmotic loads observed were partitioned into mineral cationic and anionic components, the Mg content was found to be higher in intestines of chicks, but this higher Mg was paralleled and/or surpassed by chloride (Cl) content. From these data the authors conclude that Mg-induced cartharsis is due not simply to the hyperosmotic effect of Mg per se but to neural or endocrine arcs that affect the secretion or absorption of Cl as well.

Animals↗
PubMed1987

Localization of an arenavirus protein in the nuclei of infected cells.

Host cell nuclear involvement in an arenavirus infection was examined by immunofluorescence. Both polyclonal antisera and monoclonal antibodies specific for the major nucleocapsid (N) polypeptide revealed virus-specific nuclear inclusions in Pichinde virus-infected Vero cells. Immunoprecipitation of infected cell extracts with the anti-N monoclonal antibodies and subsequent analysis by SDS-PAGE, identified two N-related proteins with mol. wt. of 36,000 (p36) and 28,000 (p28) in addition to the N polypeptide. Only those monoclonal antibodies which precipitated p28 as well as N and p36 were found to produce nuclear as well as cytoplasmic fluorescence. These findings suggest that either the p28 protein itself or a conformational variant of N was the nuclear antigen detected.

Animals↗
PubMed1987

Prevalence of low monoamine oxidase function in alcoholism.

Several studies have found a trend for low platelet monoamine oxidase activity (MAO) in alcoholism but with a great deal of overlap in MAO activity of alcoholics versus controls. The main objective of this study was to carry out a detailed assessment of MAO function that included the measurement of key kinetic parameters (i.e., Km, Vmax) in three groups of male subjects: (a) 51 hospitalized chronic alcoholics, (b) 16 recovering alcoholics with 2-10 years of abstinence, and (c) 21 controls. MAO activity was assayed radiochemically with [14C]tyramine as substrate (43-729 microM). The present study demonstrated that alcoholics had low platelet MAO activity (p less than 0.05). Kinetic analysis revealed a substantial reduction (p less than 0.01) in enzyme Vmax values of chronic and recovering alcoholics. Greater than 95% of the alcoholics had Vmax values lower than the smallest value of control subjects. Moreover, 100% of the alcoholics in both groups exhibited exceedingly low Vmax values that were below the 25th percentile of controls. In summary, results of MAO Vmax determinations provided us with a better separation of the alcoholics from controls. Measurements of platelet MAO function that include enzyme Vmax may provide us a reliable biochemical marker for alcoholism.

Adult↗
PubMed1987

The effects of forskolin on cyclic AMP, intraocular pressure and aqueous humor formation in rabbits.

Forskolin was used to study cyclic AMP-mediated regulation of aqueous humor dynamics in rabbits. Crystalline forskolin was solubilized in oil and its pharmacological effects were studied both in vitro and following topical ocular administration. In vitro, using cultured corneal epithelial cells, forskolin rapidly stimulated cyclic AMP production and in vivo increased cyclic AMP concentration in the aqueous humor 10-fold following topical administration. The effect of topical forskolin on intraocular pressure and aqueous humor formation was determined in vivo using pneumatonometry and fluorophotometry, respectively. Forskolin caused a prolonged reduction of intraocular pressure and decreased aqueous humor formation. The ability of forskolin to potentiate the ocular hypotensive effect of epinephrine was investigated. Forskolin in combination with epinephrine caused a decrease in intraocular pressure of longer duration than either 0.1% epinephrine or 1% forskolin administered separately. Forskolin caused a small but significant increase in the permeability of the blood-aqueous barrier at the time of maximal intraocular pressure reduction. This effect on the blood-aqueous barrier may explain the inhibitory effect of forskolin on aqueous humor formation.

Animals↗
PubMed1987

The impact-absorbing effects of facial fractures in closed-head injuries. An analysis of 210 patients.

A series of 210 patients with facial fractures sufficiently severe to require cranial computerized tomography (CT) to evaluate suspected closed-head injury (CHI) was studied. The injuries were separated into five grades of severity based on neurological examination, including cranial CT. The injuries were also grouped into three categories based on facial regional involvement, using chi-square contingency table analysis. The data demonstrated that patients with upper facial fractures were at greatest risk for serious CHI. Injuries to both the mandibular and the midfacial regions with no upper facial involvement more frequently resulted in mild CHI with a modest likelihood of no neurological deficits. Trauma to only the mandibular region or to only the midfacial region was least likely to involve CHI.

Adult↗
PubMed1987

Gut stasis in chickens infected with Eimeria.

The duration and locations of gut stasis were examined in chickens infected with either Eimeria acervulina or E. maxima. Gut passage time (GPT) was used to determine gut stasis. The location of feed retention was determined qualitatively and quantitatively. Infections with both species were associated with increased GPT from Days 5 to 13 postinoculation. Feed appeared to be retained in the crop and gizzard of infected birds when judged visually. However, measurements of total dry matter retained in various regions of the gastrointestinal tract did not differ significantly from each other.

Animals↗
PubMed1986

Isolated adipocytes: an assessment of cell surface changes during their preparation.

A method is described, based on the detection of adipocyte-specific cell surface antigens, which allows assessment of the relative surface damage incurred by the cells when they are prepared under a variety of conditions. Using the method it is possible to develop, for any set of reagents, a set of cell isolation conditions (collagenase concentration, time of incubation) which will produce minimally damaged cells which exhibit high levels of specific cell surface immunoreactivity. Under certain conditions a recovery from limited surface damage can be achieved, although, when cells are prepared under more extreme conditions irreversible surface damage occurs. The surface morphology of the cells as revealed by scanning electron microscopy, is also clearly affected by the conditions of cell isolation. The method has been used to define the conditions necessary for the isolation of cells to be used in the study of subtle biochemical responses.

Adipose Tissue↗
PubMed1986

Studies on the expression of adipocyte-specific cell surface antigens during the differentiation of adipocyte precursor cells in vitro.

Using species and cell specific antiadipocyte sera an immunoprecipitation procedure was developed which allowed the nature of adipocyte cell surface antigens to be investigated. Analysis of immunoprecipitates from mature adipocyte plasma membranes of rat, ox and chicken and similar 125I-labelled membranes revealed the presence of specific externally disposed adipocyte specific antigens which were also species specific. For mature cells the specific antigens had molecular weights of 124,000, 92,000 and 59,000 in the case of the rat, 87,000 in the case of the ox and 56,000, 47,000 and 37,000 in the case of the chicken. None of these antigens were cross immunoprecipated by antisera to non-homologous adipocytes. The presence of the antigens at the surface of differentiating rat while adipocyte precursor cells was demonstrated using a labelled-second antibody cellular immunoassay and the expression of this reactivity revealed to be an early event in the differentiation programme of the cells. The increase in cell surface immunoreactivity during the differentiation of the cells was shown to be dependent upon the expression of two of the antigens previously shown to be markers of the mature adipocyte phenotype. The functional identity and possible role of these antigens in the control of adipocyte differentiation in vitro and in vivo now becomes accessible to investigation experimentally.

Adipose Tissue↗
PubMed1985

A comparison of the polypeptide composition of plasma membranes prepared from the white adipose tissue and adipocytes of the mouse, rat, rabbit, ox and chicken by a Percoll self-forming gradient procedure.

The Percoll self-forming gradient method has been applied for the preparation of plasma membranes from white adipose tissue and isolated adipocytes from mouse, rat, rabbit, ox and chicken. Characterization of the membranes produced by marker enzyme analysis confirmed the general applicability of the method. The polypeptide composition of the membranes was studied by polyacrylamide gel electrophoresis. The patterns seen with tissue and adipocytes of a single species source were compared and the Coomassie blue and periodic acid Schiff staining bands characteristic of each species were compared systematically. Additionally materials from lean (FA/-) and obese (fa/fa) Zucker rats were compared. The species-specific differences in polypeptide composition form a useful basis for the further development of methods whereby the adipocyte-differentiated phenotype may be detected in a wide range of systems.

Adipose Tissue↗
PubMed1984

Corneal endothelial function and structure following cryo-injury in the rabbit.

Wide-field specular microscopy, fluorophotometry, pachymetry, and scanning electron microscopy are used to characterize a reproducible, in vivo model of corneal endothelial injury and recovery in the rabbit. Following an 8-mm central cryo-injury, the cornea remains thickened for as long as 3 weeks. Mean endothelial permeability to fluorescein is above normal for 10 days following injury, but by 14 days postinjury the endothelial permeability to fluorescein is not statistically significantly different from preinjury control values, thus indicating that endothelial permeability probably returns to normal by approximately 2 weeks postinjury. Cell morphology, as determined by scanning electron microscopy, is also essentially normal by 2 weeks postinjury. Endothelial permeability appears to recover before stromal thickness normalizes, suggesting a lag in recovery of endothelial pump function.

Animals↗
PubMed1983

Psychiatric disorders during pregnancy.

For complete care of the pregnant patient, an understanding of the psychologic aspects of pregnancy is essential. Psychologic dysfunction must be recognized early and the need for consultation presented to the patient in a nonthreatening manner. Most psychotropic drugs can be used safely. Medication should be continued as long as the benefits outweigh the risks. The postpartum period requires special attention. While approximately 16 percent of all women have emotional dysfunction during pregnancy, the postpartum incidence has been reported to be as high as 50 percent.

Abnormalities, Drug-Induced↗