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Biomedical subjects

S D Carson

Publications and source records attributed to S D Carson.

84 records · Page 5Linked to original sources
PubMed1977

Cystic fibrosis: studies with the oyster ciliary assay.

Bioassays using ciliary systems have detected a factor or factors in cystic fibrosis (CF) sera and tissue culture medium derived from CF cells. The typical shortcomings of an assay measuring biological activity have been studied, and the means to overcome the weaknesses of the oyster gill cilia assay have been established. The presence of the cystic fibrosis mucociliary inhibitor (CFMI) in experimental fractions may be determined by accepting data from only those assays in which authentic CF and normal (non-CF) fractions give defined reactions, by measuring the reaction of each sample at least three times, and by examining each experimental sample at a protein concentration greater than the minimum established in this study. The relative concentrations of the CFMI present in the first steps of purification of serum and medium have been calculated in terms of units of inhibition. Generally, the units of inhibition present in serum and medium fractions from heterozygotes are close to one-half of that in fractions from homozygous sources. Analogous fractions concentrated from a normal (non-CF) source never inhibited mucociliary activity, even when tested at nearly 100 times the CF concentration. Ciliary assays utilizing oyster gills are essential for monitoring fractionation procedures aimed at purifying the CFMI, and have been shown to be capable and reliable enough to do so.

Biological Assay↗
PubMed1976

Electrophoretic studies of the cystic fibrosis ciliary inhibitor and its interaction with immunoglobulin G.

The cystic fibrosis ciliary inhibitor (CFCI) has been partially purified from serum and plasma of cystic fibrosis (CF) homozygotes and heterozygotes, and from media of cultured fibroblasts derived from cystic fibrosis genotypes. Characterization and comparison of fractions containing the CFCI were carried out by polyacrylamide gel electrophoresis. Gel electrophoresis confirmed previous molecular weight estimations of 4,500 to 11,000 for the CFCI and provided an estimate of the number of proteins present in the fractions. Low molecular weight proteins from serum and media were combined with IgG preparations. No specific binding to IgG by the media fraction containing the CFCI could be demonstrated by the techniques employed. There was decreased binding of the low molecular weight serum fraction containing CFCI to native IgG molecules from cystic fibrosis patients as compared to IgG from normal individuals. However, IgG from CF individuals demonstrated increased binding of the cfci-containing low molecular weight serum fraction after gel filtration in the presence of guanidinium chloride. This suggests: 1) that very low concentrations of CFCI are present in media fractions; and 2) that native CF IgG cannot bind the low molecular weight CFCI fractions to the same degree as native IgG from normals or CF IgG that has been dissociated from non-covalently bound components.

Blood Proteins↗
PubMedDate not supplied

Receptor for the group B coxsackieviruses and adenoviruses: CAR.

Considerable progress towards the characterisation of the long-sought receptor, CAR (coxsackievirus and adenovirus receptor), shared by group B coxsackieviruses (CVB) and most adenoviruses (Ad) has been made since it was isolated and cloned in 1997. The primary sequence of CAR shows that it is a member of the immunoglobulin superfamily of proteins, containing two Ig superfamily domains: an amino-terminal V-like module and a C2-like module. The CAR cytoplasmic domain, representing nearly one-third of the protein, is separated from the C2-like module by a single membrane-spanning sequence. The structure of the CAR V-like module complexed with the Ad fibre knob has been determined using recombinant proteins, and reveals three CAR modules associated with a single knob. Although recombinant CAR expressed in mammalian cells confers permissivity to CVB infection, details of the interaction between CAR and CVB remain to be elucidated. The expression of CAR appears to be highly regulated with respect to both cell type and developmental age. In rodents, CAR is expressed at high levels just before birth, and declines thereafter. Expressed levels have been found to increase in regenerating muscle and in response to immunological mediators or inflammation, and in RD cells and umbilical vein endothelial cells in response to high cell density. These studies indicate that CAR expression is highly regulated, but the mechanisms and molecules that mediate the expression remain to be discovered. The physiological function of CAR and its natural ligand also remain to be discovered. In addition, while CAR expression generally correlates with viral tropism, the relationship between the physiological function of CAR and the pathologies of CVB and Ad infections remain to be described.

Adenoviridae↗
PubMedDate not supplied

Concordant expression of tissue factor and class II MHC antigens in human placental endothelium.

Villitis of unestablished etiology is a placental lesion frequently associated with high risk pregnancies: it is also found in placentae from normal term pregnancies. The etiology of the lesion is unknown. Vasculitis and thrombosis have been described in villitis areas of placentae from normal and high risk pregnancies. We asked if fetal stem vessel endothelium in villitis lesions expresses MHC class II antigens, and if this is associated with a thrombogenic activity of these vessels. We found that endothelium of fetal stem vessels in villitis areas was usually MHC class II (HLA-DR, DP and DQ) reactive. Reactivity of fetal stem vessel endothelium for MHC class II antigens was associated with the presence of tissue factor reactivity and the absence of thrombomodulin reactivity. These changes on endothelial plasma membranes can promote intravascular coagulation, ischemic necrosis, vasculitis and other histological changes characteristic of villitis.

Chorionic Villi↗
PubMedDate not supplied

Tissue factor (coagulation factor III) is present in placental microvilli and cofractionates with microvilli membrane proteins.

We have demonstrated that tissue factor is present in preparations of placental microvilli. The similarity of the procoagulant activities of microvilli and placental homogenates indicate that tissue factor is neither deficient nor enriched in microvilli relative to the bulk of placental tissue. On the basis of solubility in Triton X-100 and ammonium sulphate, and its affinity for phenyl-Sepharose, microvilli tissue factor is indistinguishable from that in whole placental homogenates.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

Congenital heart surgery: a five year study.

The practice of surgery for congenital heart disease has undergone a major evolution in the past few years. Technical advances, the introduction of operative procedures, and a change in philosophy relating to the proper timing of surgical intervention are the major factors responsible for this change. To document our experience, a comprehensive review of all surgery performed for congenital heart disease at the University of Colorado Health Sciences Center during the last five years was conducted.

Cardiac Surgical Procedures↗
PubMedDate not supplied

Activation of coagulation factor X in human semen.

Tissue factor (TF) is an essential cofactor for factor VII (fVII) in initiating blood coagulation. Recently, TF was shown to be present in human semen and to be associated with prostasomes that originate from prostatic secretions. In the blood coagulation cascade, the complex of TF and activated factor VII (fVIIa) can activate both factor X and factor IX, by limited proteolysis. In the present study, we investigated the ability of semen to activate factor X. We also determined that factor X was activated predominantly by TF-fVIIa and that most of the TF was present in the seminal plasma, consistent with prostasome localization. No endogenous factor X was detected in semen, but activation of added factor X occurred in the absence of added fVIIa. Subsequent experiments showed that seminal plasma contains endogenous fVII-like activity, but the addition of more fVIIa increased factor X activation. Thus, while seminal plasma contains significant amounts of TF, its potential to activate factor X is limited by fVII availability and by the absence of endogenous factor X. Evaluation of semen specimens from infertility patients revealed a 16-fold variation in TF-fVII activity. No relationship between TF and number of days of abstinence, specimen pH, sperm count, or sperm motility was evident. Additional factor X-activating potential, independent of further TF activity, was generated in seminal plasma after treatment of semen with calcium and ionophore A23187. Production of this additional activity was blocked by the addition of anti-TF antibody during the activation. Since there is no factor X endogenous to semen, the additional activity stimulated by A23187 appears to be due to an endogenous, non-factor X substrate for TF-fVII in semen. This endogenous substrate may be either factor IX or a novel new substrate for TF-fVIIa. Future experiments will test these hypotheses.

Animals↗