Use of nucleic acid hybridization for specific detection of submicrogram quantities of DNA, and its application to human plasma.
(57/1906)
A technique is described for using radiolabeled RNA complementary to human DNA as a probe for the specific identification of submicrogram concentrations of human DNA by formation of RNA-DNA hybrids. An example is given of its application to the semiquantitation of human DNA in human plasma, a substance that is ordinarily difficult to examine because materials are present that interfere with the usual colorimetric or fluorometric assays. An example is also given of the use of an analogous approach to analyzing rabbit serum for circulating bacterial DNA. Unique to the hybridization technique is a degree of specificity sufficient to identify specific base sequences and hence the origin of the DNA being detected, a point that may be important in the examination of circulating DNA reported to occur in patients with systemic lupus erythematosis. This technique may also be of value in clarifying the presently conflicting data regarding the occurrence of free DNA in the normal human circulation. (+info)
Analysis of the roles of ICAM-1 in neutrophil transmigration using a reconstituted mammalian cell expression model: implication of ICAM-1 cytoplasmic domain and Rho-dependent signaling pathway.
(58/1906)
Interaction between ICAM-1 (CD54) and fibrinogen (fg) has been shown to enhance leukocyte adhesion, but its specific role in the process of migration across endothelial cell junctions remains unclear. To overcome the problem of multiple adhesion receptors found on endothelial cells, we have engineered stable Chinese hamster ovary cell lines expressing ICAM-1 (Chinese hamster ovary ICAM-1). The transfection of ICAM-1 alone in these cells is sufficient to recapitulate the entire process of neutrophil adhesion and transmigration. This phenomenon was mediated by fg-ICAM-1 interactions, as depletion of fg, as well as the use of an Ab that specifically inhibits ICAM-1-fg interaction (2D5), completely abolished the effect of ICAM-1 expression on PMN transmigration. In addition, this ICAM-1-mediated transmigration is clearly dependent on the occurrence of fg-ICAM-1 interactions on the monolayer, and not on neutrophils, as the preincubation of the PMN with the mAb was ineffective. Furthermore, PMN transmigration, but not adhesion, is totally abolished when the ICAM-1 cytoplasmic domain is deleted, indicating that signaling inside the cell is required to mediate the fg-ICAM-1 effect on transmigration. Using a specific inhibitor of the small GTP-binding protein Rho, we have obtained evidence that this signaling cascade is involved. Thus, our results clearly show that ICAM-1 plays a key role in the migration of leukocytes across cell junctions, and indicate that this phenomenon is not a direct consequence of the enhanced adhesion mediated by the expression of ICAM-1. (+info)
Actin reorganization and proplatelet formation in murine megakaryocytes: the role of protein kinase calpha.
(59/1906)
With the recent cloning and characterization of thrombopoietin, appreciation of the molecular events surrounding megakaryocyte (MK) development is growing. However, the final stages of platelet formation are less well understood. Platelet production occurs after the formation of MK proplatelet processes. In a study to explore the molecular mechanisms underlying this process, mature MKs isolated from suspension murine bone marrow cell cultures were induced to form proplatelets by exposure to plasma, and the role of various cell-signaling pathways was assessed. The results showed that (1) bis-indolylmaleimide I, which blocks protein kinase C (PKC) activation; (2) down-modulation of conventional or novel classes of PKC by phorbol myristate acetate; and (3) ribozymes specific for PKCalpha each inhibited proplatelet formation. Inhibition of several MAP kinases, PI3 kinase, or protein kinase A failed to affect MK proplatelet formation. To gain further insights into the function of PKCalpha in proplatelet formation, its subcellular localization was investigated. In cultures containing active proplatelet formation, cytoplasmic polymerized actin was highly aggregated, its subcellular distribution was reorganized, and PKCalpha colocalized with the cellular actin aggregates. A number of MK manipulations, including blockade of integrin signaling with a disintegrin or inhibition of actin polymerization with cytochalasin D, interrupted actin reorganization, PKC relocalization, and proplatelet formation. These findings suggest an important role for PKCalpha in proplatelet development and suggest that it acts by altering actin dynamics in proplatelet-forming MKs. Identification of the upstream and downstream pathways involved in proplatelet formation should provide greater insights into thrombopoiesis, potentially allowing pharmacologic manipulation of the process. (+info)
Use of postpheresis plasma to improve granulocyte yields for transfusion.
(60/1906)
Humoral factors which stimulate release of mature granulocytes from body reserves are presumed to be the mechanism through which high yields of granulocytes are obtained from donors by filtration leukopheresis. Postpheresis plasma (PPP) obtained 2 hr after leukopheresis, when infused into normal rats, induced a peak granulocytosis at 3 hr of 22,000/cu mm above controls. A substance in the nylon filters, which caused a peak granulocytosis at 4 hr of 7600/cu mm above controls, was eliminated by washing the filter with 30 volumes of saline. Injection of PPP obtained following leukopheresis with washed filters resulted in an 8000/cu mm increase in granulocytes. One milliliter of PPP given 1 hr before pheresis increased the granulocyte yield from 4.3 to 8.7 times 10-7 granulocytes in a 2-hr run. We conclude that (1) a humoral substance elaborated by the host during filtration leukopheresis induces a granulocytosis in the donor, (2) a substance in commercial leukopaks, which can be eliminated by vigorous washing of the filters, may be responsible in part for granulocytosis observed during leukopheresis, (3) PPP may be used to increase granulocyte yields in donors undergoing leukopheresis. (+info)
The pharmacokinetics of 4-acetyl tritium vinblastine in two patients.
(61/1906)
Vinblastine, labeled with tritium in the 4-acetyl group, was given to two patients with malignant disease, and the pharmacokinetic behavior of the drug was determined. Clearance of radioactivity from the blood was biphasic, with t1/2 values for a first rapid phase of 4.25 and 4.78 min, and for a slower phase of 185 and 195 min. The volume of the central compartment was calculated as 29.7 and 39.4 liters, while the total fictive volume of distribution was 86.4 and 111.4 liters. Binding to blood components occurred in the order: plasma greater than platelets greater than red blood cells greater than white blood cells. Excretion of radiolabel occurred via the stool and the urine so that, after 72 hr, 25 and 41% of the total dose had appeared in the former and 19 a nd 23% had appeared in the latter. Appreciable amounts of unchanged drug appeared in the urine, while very little appeared in the stool, suggesting hepatic metabolism, consistent with prior animal studies. (+info)
Effect of carbon cup aging on plasma zinc determination by flameless atomic adosorption spectrometry.
(62/1906)
Determination of zinc in blood plasma by flameless atomic absorption spectrometry is discussed, with particular reference to the protocol required for the successful use of the Varian-Techtron Carbon Rod Atomizer. Cup aging is shown to be an important factor in limiting the precision of this analytical technique and ways of minimizing the problem are described. Matrix problems have also been encountered, which precluded the use of aqueous standard curves and the method of standard additions. We propose the use of plasma in preparing standard curves, the values for which are corrected for inherent plasma zinc, as a possible solution to the problem. (+info)
Evidence of porcine endogenous retroviruses in porcine factor VIII and evaluation of transmission to recipients with hemophilia.
(63/1906)
Since 1984, unheated porcine clotting factor VIII (Hyate:C) has been used to treat severe bleeding episodes in persons with hemophilia who have antibodies to human clotting factor. We document the presence of porcine endogenous retrovirus (PERV) in plasma samples of pigs and in clinical lots of Hyate:C. Both gag and pol PERV RNA sequences were detected by reverse-transcriptase (RT) polymerase chain reaction in 13 of 13 lots of Hyate:C tested. Among 10 of these lots, RT activity also was detected, which confirms the presence of retroviral particles. To assess the transmission of PERV to Hyate:C recipients, we tested serum specimens from 88 recipients of Hyate:C and 23 noninfused control subjects for anti-PERV antibodies by using a Western blot assay. None of the samples was positive. Our data document that PERV particles are a common contaminant of Hyate:C products and suggest that the risk of PERV transmission from these percutaneous exposures is very low. (+info)
Tensile bond strength of a light-cured glass ionomer cement when used for bracket bonding under different conditions: an in vitro study.
(64/1906)
The purpose of this study was to investigate the tensile bond strength of a new light-cured resin reinforced glass ionomer cement (Fuji Ortho LC), following the bonding of stainless steel brackets to 40 extracted human premolar teeth under four different enamel surface conditions: (1) non-etched, moistened with water; (2) etched, moistened with water; (3) etched, moistened with human saliva; and (4) etched, moistened with human plasma. The etched surface produced a higher bond strength than the non-etched surface when contaminated with distilled water. Contamination with human saliva resulted in a further increase in bond strength whilst plasma contamination produced an even higher strength. However, one-way analysis of variance showed no statistically significant difference between the various groups. After debonding, enamel and bracket base surfaces were examined for residual adhesive. The location of the adhesive also indicated improved bonding to etched enamel. This investigation shows that regardless of enamel surface pretreatment or environment, Fuji Ortho LC provides an adequate strength for bonding of orthodontic brackets. (+info)