Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PLASMA PROTEINS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed2003

A strategy of plasma protein quantitation by selective reaction monitoring of an intact protein.

Immunoassays are used extensively in the quantitative analysis of proteins in plasma, urine, and other biological matrixes to support preclinical and clinical studies. Although immunoassays are both sensitive and rapid, difficulties during development of these assays are compounded by the need to have a specific antibody or antigen to the protein of interest. Furthermore, calibration curves of immunoassays are inherently nonlinear, and the technique often detects many structurally related components in addition to the analyte of interest. We have developed a novel strategy of analyzing protein concentrations in plasma by utilizing 96-well solid-phase extraction and LC-MS/MS detection of the intact protein. This strategy has been successfully applied in method development and assay validation of quantitatively analyzing protein rK5 concentrations in monkey plasma samples. Additional techniques such as precolumn regeneration and column heating were also incorporated into the assay. Total run time for each sample was approximately 15 min. An LLOQ of 99.2 ng/mL from a sample volume of 50 microL, corresponding to only 380 fmol (3.97 ng) of the rK5 analyte being injected onto the analytical column (assuming 100% extraction recovery), was obtained. The validated linear dynamic range was between 99.2 and 52 920.0 ng/mL, with a correlation coefficient (r(2)) ranging from 0.9972 and 0.9994. The intraassay CV for this assay was between 0.6 and 3.8%, and the interassay CV was between 1.7 and 3.2%. Interassay mean accuracies were between 101.5 and 104.7%. The assay has proven rugged and specific and has been employed to generate data in support of preclinical studies. This strategy for rK5 assay could be used for the development of bioanalytical assays to provide preclinical and clinical support for other protein drug candidates and, furthermore, for the validation of biomarkers discovered from proteomic research.

Amino Acid Sequence↗
PubMed1998

Biophysical characterization of the interaction of bovine seminal plasma protein PDC-109 with phospholipid vesicles.

PDC-109 is the major protein of bovine seminal plasma. It binds to the bovine sperm surface at ejaculation and modulates sperm capacitation. PDC-109 displays phosphorylcholine- and heparin-binding activities which are thought to account for its sperm surface coating and glycosaminoglycan-induced sperm capacitating activities, respectively. We have characterized the interaction of isolated PDC-109 with membranes of phospholipid vesicles using a biophysical approach. Our results show that PDC-109 interacts not only with the solvent-exposed phosphorylcholine head group but also with the hydrophobic core of liposomes. Binding of PDC-109 to membranes is a very rapid, biphasic process with half times of less than one second. Maximal binding of PDC-109 to small unilamellar vesicles was achieved with a stoichiometric ratio of 10-11 phosphatidylcholine molecules/PDC-109 molecule. Incorporation of phosphatidylethanolamine or phosphatidylserine into phosphatidylcholine vesicles reduced the binding of PDC-109, suggesting that both the density of phosphorylcholine groups and the surface charge determine the interaction of the seminal plasma protein with the surface of the membrane. Electron spin resonance measurements showed that binding of PDC-109 to phosphatidylcholine vesicles caused a rigidification of the membrane. The relevance of the data for describing the role of PDC-109 in the modulation of sperm capacitation is discussed.

Animals↗
PubMed1978

Comparative immunological analysis of host plasma proteins bound to bloodstream forms of Trypanosoma brucei subspecies.

The presence, location, host specificity, identity, and quantity of rat plasma proteins bound to bloodstream forms of Trypanosoma brucei subsp. brucei, T. brucei subsp. rhodesiense, and T. brucei subsp. gambiense were determined by a quantitative indirect fluorescent-antibody method and gel immunoassays. Fluorescence differences between trypanosomes obtained from rats and mice and treated with antiserum to normal rat plasma indicated that most, if not all, of the bound plasma proteins were host specific. Removal of plasma proteins by trypsinization of parasites provided evidence for their attachment to the surface of the parasite. The accreted proteins were found to be host albumin, immunoglobulin G (IgG), and complement (C3). The same quantities of these three plasma proteins were present on T. brucei subspecies collected from normal rats at 2 days postinfection, during low or peak parasitemias, or from cortisone-treated rats. IgM could only be detected on parasites collected from normal rats at peak parasitemia. With the aid of rocket immunoelectrophoresis, host albumin and IgG were found to account for 0.2 and 0.05%, respectively, of the total soluble proteins of the bloodstream forms. It was concluded from this study that: (i) host plasma proteins were bound to parasites early in the infection, suggesting a mechanism of adaptation to the mammalian host; (ii) the surface-bound IgG was not the result of a specific immune response against the parasites but might be the cause of C3 attachment; (iii) among the bloodstream forms of the three T. brucei subspecies, there were no differences in amounts of surface-bound albumin, IgG, or C3. A comparison between the present data dealing with T. brucei subspecies, on the one hand, and the previously published results concerning T. congolense, on the other, revealed significant differences in the amounts of the host plasma proteins attached to these hemoflagellates.

Animals↗
PubMed1981

Plasma proteins in fetal sheep brain: blood-brain barrier and intracerebral distribution.

1. Plasma proteins have been demonstrated to be present in early fetal sheep brain in amounts which cannot be accounted for by blood contamination. 2. The distribution of alpha-fetoprotein, albumin, fetuin, alpha 1-antitrypsin and transferrin has been studied by immunoassay of extracts from brain homogenates and by immunoperoxidase histochemistry of fetal brains between 37 and 125 days gestation (term is 150 days). 3. At 35 days gestation fetuin and albumin were quantitatively the most important proteins in fetal brain, both as estimated by extraction and by immunohistochemistry. Both of these proteins, and also alpha-fetoprotein and alpha 1-antitrypsin, declined considerably in amount by 60 days gestation. After 60 days the concentrations of albumin and alpha-fetoprotein were not significantly different from that due to blood contamination and only occasional cells could be demonstrated by immunohistochemistry. Fetuin and alpha 1-antitrypsin were present in reduced but significant amounts at least up to 125 days gestation. 4. The immunohistochemical results showed that considerable numbers of immature neurones were stained for some plasma proteins. Fetuin positive cells predominated both in terms of the larger number of cells which stained at 35-40 days gestation and in the persistence of positive cells up to 125 days gestation. Numerous cells in the neuroependymal layer and in several layers of the developing cortical plate were positive, especially early in gestation. Only a few transferrin or alpha 1-antitrypsin positive cells were observed. 5. Permeability of the blood-brain barrier to sheep or human serum albumin (labelled with 125I) was tested in 60 day fetal sheep by intravenous injection and estimation of brain radioactivity at 3 or 6 hr with allowance for blood contamination. Only a very small (but significant) penetration of protein was detected. Unlike penetration of protein into c.s.f. at the same age, it did not reach its natural steady state in brain. 6. It is concluded that the blood-brain barrier to protein is well developed in the immature fetal sheep but that developing neurones probably acquire certain plasma proteins directly from the c.s.f. when they are differentiating in the neuroependyma. The subsequent distribution of plasma protein positive cells in different brain regions is suggested to be due to the migration of developing neurones for the neuroependyma although the possibility of local synthesis of plasma proteins has not been excluded.

Albumins↗
PubMed1993

Clinical studies on plasma protein C. Correlation with serum cholinesterase.

When compared to 32 healthy normal weight normolipidemic control subjects, plasma protein C antigen and serum cholinesterase activity were significantly decreased in 17 patients with decompensated cirrhosis of the liver and in 29 critically-ill surgical patients displaying the acute phase reaction, most of them without evidence of consumption coagulopathy. The low levels of these variables are considered to be subsequent to impaired and dysregulated hepatic protein synthesis. On the contrary, plasma protein C and serum cholinesterase were increased in 20 nephrotic patients and in 20 overweight hypertriglyceridemic subjects, a finding highly suggestive of enhanced hepatic synthesis probably related to an accelerated turnover of triglycerides. A discrepancy between low serum cholinesterase activity and normal or even high plasma protein C antigen was noted in 15 patients with cholestasis. This was particularly evident in 7 subjects with extrahepatic cholestasis and an abnormal pattern of hepatic protein synthesis or impaired clearance of plasma protein C would appear to develop in such pathological conditions.

Adult↗
PubMed1976

Effect of halothane and halothane-nitrous oxide on hematocrit and plasma protein concentration in dog and monkey.

Hematocrit and plasma protein concentration in healthy dogs and monkeys (Macaca arctoides) awake and anesthetized with halothane-oxygen and halothane-nitrous oxide oxygen were compared during conditions of spontaneous and controlled ventilation. Both hematocrit and plasma protein concentration decreased within 15 minutes following anesthetic induction. This decrease persisted throughout constant- or variable-depth anesthesia and did not vary appreciably with ventilation, anesthetic dose, or introduction of nitrous oxide. Plasma volume, determined by a dye dilution technique, concomitantly increased. This increase is compatible with the directional changes in hematocrit and plasma protein.

Anesthesia, Inhalation↗
PubMed1975

Plasma protein binding of drugs as a function of age in adult human subjects.

The intent of this study was to determine what influence, if any, increasing age has on the binding of drugs by plasma proteins. Plasma from healthy subjects ranging in age from 21 to 94 years was used. The binding of phenytoin (diphenylhydantoin) (acid), penicillin G potassium (benzylpenicillin potassium), and phenobarbituric acid was determined by equilibrium dialysis of 14C-labeled compounds. No differences were found in total protein concentration; however, albumin was reduced in subjects over 50 years of age. Plasma binding of each drug studied was not related to age; this finding suggests that age per se is not a factor in the binding of drugs by plasma proteins.

Adult↗
PubMed2002

The acute phase response of rainbow trout (Oncorhynchus mykiss) plasma proteins to viral, bacterial and fungal inflammatory agents.

The innate arm of the immune system responds to inflammatory stimuli by the activation of phagocytes, and by altered levels of several plasma proteins. These changes in plasma proteins comprise a major component of the acute phase response, which is thought to be an adaptive response that contributes to regaining homeostasis after tissue injury or infection. In this study, rainbow trout (Oncorhynchus mykiss) were injected with a variety of potential inflammatory agents, and changes in the concentrations of plasma proteins were sought in polyacrylamide gels in which plasma proteins had been electrophoresed. Bacteria, viruses and yeast all induced changes in plasma protein profiles. Increases were first evident 2 days after injections, and most were evident within 1 week. The greatest number of changes occurred after injection with a Vibrio bacterin emulsified in Freund's incomplete adjuvant. While some proteins increased and others decreased following several treatments, other proteins changed only in response to injections of viruses or viral proteins, and others changed in response to bacterial components. Some proteins that increased after yeast injection decreased after injection of viral components. The partial amino acid sequence of one increased protein identified it as haptoglobin.

Acute-Phase Proteins↗
PubMed2005

Modification of the ultrafiltration technique to overcome solubility and non-specific binding challenges associated with the measurement of plasma protein binding of corticosteroids.

Plasma protein binding (PPB) methodology suitable for application in the lead optimisation of a corticosteroid series known to demonstrate non-specific binding (NSB) and poor solubility has been established. The method involved a modification to standard ultrafiltration (UF) techniques. In parallel with each experimental plasma sample, a control plasma sample was also processed by ultrafiltration. The retentate from experimental and control plasma samples were mixed back into the filtrate of the partner sample. The resulting regenerated plasma samples, one representing the experimental filtrate and one representing the experimental retentate, were then analysed by LC/MS/MS. Varying degrees of NSB were demonstrated with a number of corticosteroids, and this effect was eliminated using the modified method. Validation using a panel of established corticosteroids showed good agreement with published PPB figures. The published PPB figure for fluticasone propionate (FP) was, however, found to be an underestimate, and this was subsequently confirmed, at clinically relevant plasma concentrations, to be 99.3%. The modified method was particularly suited to lead optimisation because it provided samples in a consistent matrix compatible with standard high throughput LC/MS/MS analysis.

Adrenal Cortex Hormones↗
PubMed1979

Radiolabeled sucrose covalently linked to protein. A device for quantifying degradation of plasma proteins catabolized by lysosomal mechanisms.

A general method is described for assessing the degradation of proteins metabolized by lysosomal mechanisms. The method depends on the lysosomal trapping of sucrose which is covalently bound to the protein of interest and thus caried into the lysosome with it. The validity of the method was demonstrated in vitro in studies of the catabolism of low density lipoprotein (LDL) by cultured fibroblasts. Sucrose-derivatized LDL was not distinguished from 125I-LDL by fibroblasts, either in terms of surface binding or rate of uptake. 14C from [14C]sucrose-LDL accumulated in the cells as predicted; very little appeared in the trichloroacetic acid-soluble fraction of the medium (2% of total uptake). 14C-labeled metabolites in the cells (modal apparent Mr = 1000-2000) were separated from undegraded LDL by gel filtration. LDL degradation calculated from the 14C metabolites accumulating intracellularly was in excellent agreement with that calculated from paired studies using 125I-LDL. Finally, the validity of the method was demonstrated in vivo using asialofetuin, a protein previously shown to be selectively taken up and degraded by the liver. In principle, the method described should be applicable to the study of the sites of degradation of any of the plasma proteins.

Animals↗
PubMed1992

Plasma protein binding of quinine: binding to human serum albumin, alpha 1-acid glycoprotein and plasma from patients with malaria.

The binding of quinine to human serum albumin (HSA), alpha 1-acid glycoprotein (AAG) and plasma obtained from healthy subjects (10 caucasians and 15 Thais) and from Thai patients with falciparum malaria (n = 20) has been investigated. In healthy volunteers, plasma protein binding expressed as the percentage of unbound quinine was 7.9-31.0% (69-92.1% bound). The mean percentage of unbound quinine found with essentially fatty acid-free HSA (40 g L-1) was 65.4 +/- 1.5% (mean +/- s.d.) and was comparable with the value (66.3 +/- 3.8%, mean +/- s.d.) for Fraction V HSA (40 g L-1). This suggests that fatty acids do not influence the plasma protein binding of quinine. Binding of quinine to 0.7 g L-1 AAG was high (mean unbound 61.0 +/- 5.0%), indicating that quinine is bound primarily to AAG and albumin, although other plasma proteins such as lipoproteins may be involved. The mean percentage of unbound quinine was slightly less in caucasians (14.8 +/- 6.7% unbound), compared with healthy Thai subjects (17.0 +/- 6.7% unbound). The higher binding of quinine in caucasian subjects was associated with a higher plasma AAG concentration observed in caucasians. Mean percentage of unbound quinine was significantly lower in Thai patients with malaria (10.9 +/- 4.0%) than in the healthy Thai subjects. The increase in the extent of quinine binding corresponded with the increase in the acute-phase reactant protein, AAG in the patients with malaria. Overall, when the data were combined there was a significant correlation (r = 0.846, P < 0.005) between the binding ratio (bound/unbound) of quinine and the plasma AAG concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluorescence↗
PubMed1981

Direct effect of insulin on the synthesis of specific plasma proteins: biphasic response of hepatocytes cultured in serum- and hormone-free medium.

Monolayers of chicken embryo hepatocytes. cultured in chemically defined medium, retain the ability to synthesize a wide spectrum of plasma proteins for several days in the absence of added hormones. Addition of insulin to the medium elicited a biphasic stimulation of plasma protein synthesis: a rapid response of the synthesis of a limited number of plasma proteins (e.g., albumin and alpha 1-globulin "M"), then, after prolonged exposure to the hormone, the involvement of additional plasma proteins (e.g., fibrinogen and lipoproteins). Synthesis of transferrin and a few other plasma proteins was not affected by the presence of insulin. The degree of stimulation for the most response plasma proteins ranged between 2- to 4-fold during the early phase and 10- and even 30-fold during the late phase of the cells' response t insulin. Stimulated synthesis in the early phase was detected within 1 hr and was rapidly reversible. Plasma protein synthesis in culture was sensitive to concentrations of insulin below 0.35 nM, well within the physiological range. The delayed response was elicited only at higher hormone levels. Parallels between the control of synthesis of plasma proteins in this system and that observed in diabetic animals suggest that the embryonic chicken hepatocytes may be a useful model for studying liver function in diabetes as well as insulin action in general.

Animals↗
PubMed2026

Plasma proteins are integral to cross-tissue gene regulatory networks implicated in cardiometabolic disorders and coronary artery disease.

The plasma proteome has demonstrated promise for identifying diagnostic markers for cardiometabolic disorders (CMDs) and coronary artery disease (CAD). However, identifying the organ of origin for these biomarkers is critical for establishing biological relevance. We performed a multi-omic integrative analysis across multiple tissues from the STARNET study by profiling 974 plasma proteins in 532 CAD patients, integrating RNA sequencing (RNA-seq) data from the arterial wall, major metabolic organs, and blood. We identified 144 cis-protein quantitative trait loci in plasma, colocalizing with tissue cis-expression quantitative trait loci. Additionally, by mapping tissue mRNA "seed genes," we traced 262 plasma proteins to their source organs, primarily the liver. Crucially, we found that 851 plasma proteins are associated with the activity of cross-tissue gene regulatory networks (GRNs), including GRNs implicated in CMD and CAD development. Our findings demonstrate that plasma proteins are integral components of GRNs, with potential for developing reliable diagnostics and precise therapeutic targets. A record of this paper's transparent peer review process is included in the supplemental information.

cardiometabolic disorders↗
PubMed1981

A human neutrophil-dependent pathway for generation of angiotensin II: purification and physicochemical characterization of the plasma protein substrate.

Human neutrophils contain a neutral protease, previously designated "neutral peptide-generating protease," which generates a smooth muscle contractile activity from a plasma protein substrate. The plasma protein substrate has been purified to homogeneity from fresh citrated human plasma by 45% (wt/vol) ammonium sulfate precipitation of contaminating proteins, Affi-Gel Blue affinity chromatography, hydroxylapatite chromatography, phenyl-Sepharose hydrophobic chromatography, and Sephacryl S-200 gel filtration. The purified product produced a single stained protein on alkaline disc gel electrophoresis and elicited a monospecific goat antiserum. Purification was approximately 330- to 350-fold, and overall recovery was 6-11% of substrate protein in starting plasma as determined by quantitative radial immunodiffusion assay. The substrate has an isoelectric point of pH 4.6-5.1 and is a single polypeptide chain glycoprotein of Mr 62,000-67,000 by sodium dodecyl sulfate electrophoresis. The mean(+/- SD) concentration of this plasma protein substrate in normal serum is 120 +/- 22 microgram/ml. The plasma protein substrate of the neutrophil neutral protease may be identical to human angiotensinogen (renin substrate) because the physicochemical characteristics are similar and the peptide product is recognized by antibody to angiotensin II.

Angiotensin II↗
PubMed1982

The effect of saturable binding to plasma proteins on the pharmacokinetic properties of disopyramide.

Disopyramide exhibits saturable binding to plasma proteins in the therapeutic plasma concentration range. Because of this property, controversy exists in the literature regarding the pharmacokinetic properties of the drug. The purposes of this study were to reassess the pharmacokinetic properties of disopyramide in humans, taking into consideration both total and unbound concentrations and to use disopyramide as a model compound to study the effect of drug binding on the renal clearance of both total and unbound drug. A single intravenous dose of disopyramide (1.5 mg/kg) was administered to eight normal volunteers. Blood and urine samples were collected for 36 h. Total concentrations of disopyramide in plasma and urine were determined by high pressure liquid chromatography. Binding of disopyramide to plasma proteins was determined by equilibrium dialysis. In all subjects the binding of disopyramide to plasma proteins was saturable, but there were considerable differences in binding between subjects. The volume of distribution, total body clearance, and renal clearances of both total and unbound drug were calculated. Because only the total body clearance and renal clearance of unbound compound are not dependent upon unbound fraction (alpha), these are the only parameters which can be reported without qualification as to the concentration. The mean +/-DS total body clearance of unbound drug in the eight subjects was 5.40 +/- 2.80 ml/min/kg. About 50% of this was due to renal elimination. A statistically significant negative correlation of the renal clearance of total disopyramide with time was observed in seven of eight subjects, whereas a significant correlation between the renal clearance of unbound disopyramide and time was observed in only one subject. This suggests that the renal clearance of unbound disopyramide is independent of alpha, while the renal clearance of total disopyramide is dependent upon alpha.

Adult↗
PubMed1996

Endocytotic functions of ameloblasts and odontoblasts: immunocytochemical and tracer studies on the uptake of plasma proteins.

BACKGROUND: Biochemical, (immuno)cytochemical, and radioautographic data accumulated over several years have lead to the view that ameloblasts carry out both secretory and degradative functions throughout amelogenesis. Whereas it has been assumed that maturation stage ameloblasts endocytose aged enamel proteins from the enamel layer, the origin of the newly formed ones detected in the endosomal/lysosomal compartment of ameloblasts from all stages remains to be elucidated. One possible source is from secretory products released ectopically along basolateral surfaces. METHODS: To test this hypothesis, we have investigated, using colloidal gold immunocytochemistry, whether plasma proteins (albumin and alpha 2HS-glycoprotein) found in the interstitial fluid are endocytosed by rat incisor ameloblasts and other cells from hard and soft tissues. Rat albumin, tagged with dinitrophenol, was injected intravenously to trace the movement of this protein. RESULTS: Plasma proteins were immunodetected along the baso-lateral surfaces and in multivesicular bodies of ameloblasts where enamel proteins were also found. By 2 hours following intravenous administration of dinitrophenylated albumin, the tracer had left the blood and diffused into the enamel organ and between odontoblasts and osteoblasts. The tracer was also found in multivesicular bodies of all cells examined. CONCLUSIONS: The uptake of albumin by many different cell types suggests that this process is not restricted to ameloblasts and likely occurs in a nonselective manner. Hence, baso-lateral uptake in ameloblasts may play a role not only in the continuous removal of plasma proteins leaking from the blood, but also of enamel proteins 'dumped' laterally between these cells. Likewise, odontoblasts may use the same mechanism to internalize some of the plasma proteins and any enamel protein that diffuse toward them.

Albumins↗
PubMed1985

Binding of quinine to plasma proteins in falciparum malaria.

Plasma protein binding of quinine was measured in 12 patients with cerebral malaria on the first and seventh day of treatment, and in 7 patients with uncomplicated falciparum malaria on admission and also one month later. Binding was significantly higher and therefore the proportion of free drug was lower in cerebral malaria patients (free: total quinine concentration; 7.2 +/- 3.5%, mean +/- SD, on admission; 7.4 +/- 5.3% on day 7) compared with uncomplicated malaria patients on admission (10.2 +/- 5.8%) or following recovery (11.0 +/- 5.5%, n = 6) P = 0.011. Binding was significantly correlated with the red cell/total concentration ratio r = 0.56, P less than 0.0001. The ratio of cerebrospinal fluid to free (unbound) plasma quinine was 0.55 +/- 0.33 which suggests that quinine does not freely cross the blood brain barrier. These findings are relevant to the interpretation of total plasma or serum concentration, and may explain the rarity of serious quinine toxicity in severe falciparum malaria.

Blood Proteins↗
PubMed1982

Diurnal variations in cobalamin binding plasma proteins.

The diurnal variations in cobalamin-binding plasma proteins were studied in 10 healthy volunteers. The unsaturated cobalamin-binding capacities of transcobalamins (TC-II and R-binders), P-cobalamin and P-protein were measured every third hour during 24h. Only small variations within an interval of +/- 20% were found. Highly significant decrements during the night were a uniform finding. After correction for variations of total plasma protein, the changes became less prominent, but still significant for P-cobalamin and P-R-binders. Hence the mean values of P-R-binders and P-cobalamin were 113 and 533 pmol/1 at 9:00 h, and decreased 12 and 8%, respectively, at 3:00 h. When using cobalamin binding plasma proteins in the monitoring of various malignant, haematological and autoimmune disorders, the specimens should, therefore, be collected at defined hours and in a uniform posture.

Adult↗