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At least 145 records · Page 8Linked to original sources
PubMed1996

The lymphatic circulation plays a dynamic role in blood volume and plasma protein restitution after hemorrhage.

The purpose of this study was to determine the contribution of the lymphatic circulation to blood volume and plasma protein restitution after hemorrhage. Splenectomized sheep were prepared with thoracic duct and vascular catheters. The day after surgery, thoracic duct lymph flow, thoracic duct lymph protein, plasma protein, mean arterial pressure, and blood volume were measured. After 12 h, awake sheep were either bled 25% of blood volume over 5 min (HEM; n = 6) or observed (SHAM; n = 5) and measurements were recorded for 48 h. In HEM, the thoracic duct protein return rate and thoracic duct lymph flow transiently decreased (0-.5 h) but were then equal to or greater than that in SHAM. In HEM, there was restitution of both blood volume and plasma protein mass approximately 12 h after hemorrhage. Both thoracic duct lymph flow and protein return rate are significant contributors to blood volume and plasma protein restitution after hemorrhage. These findings and the prior demonstration by the authors that lymphatic vessel pumping is increased after hemorrhage suggest a dynamic role for the lymphatic circulation in blood volume homeostasis after hemorrhage.

Analysis of Variance↗
PubMed1999

Affinity chromatography of plasma proteins (guanidinobenzoatase): use of mimetic matrices and mimetic soluble ligands to prevent the binding of albumin on target affinity matrices.

Serum albumin is the most abundant protein in plasma and it has a high capacity to bind many small compounds and macromolecules. In this way, albumin may promote important interferences during affinity chromatography of plasma proteins. Guanidinobenzoatase (GB) is a very relevant plasma protease that seems to be related to tumoral processes. This enzyme may be adsorbed on tailor-made agmatine-amide-agarose (CH-A) supports (e.g., the ones having 2 micromol of guanidino groups per ml of agarose attached to the support, through a 6 C aliphatic chain). Such tailor-made supports containing a very low concentration of ionized groups are hardly able to adsorb any protein by anion-exchange. However, they are able to strongly adsorb albumin. In order to solve this problem new mimetic affinity matrices have been designed: (i) by using the same ligand immobilized through a different chemical linkage [guanidino groups attached via secondary amino bonds, (AEA)] or (ii) by using slightly different ligands (e.g., 1,8-octanediamine containing a primary amino group instead of a guanidino one) also attached to the support via amido bonds (CH-DAO). Albumin adsorbs on the target and on the two mimetic matrices while GB is mainly adsorbed on the target one. Moreover, the adsorption of albumin on the affinity matrix (CH-A) is very strongly inhibited by the presence of low concentrations of soluble ligands (e.g., 1,8-octanediamine containing two ionized primary amino groups). On the contrary, the adsorption of GB on CH-A is hardly inhibited by the presence of such mimetic soluble ligand. In this way, the former offering of crude GB samples to AEA plus the use of mimetic inhibitors during adsorption of the extract on CH-A completely prevent the undesirable adsorption of albumin. In a such way, an extremely selective adsorption of GB can be performed. Such an improved chromatography procedure allows a very easy affinity purification and detection of GB.

Agmatine↗
PubMed1980

Hormonal and immunological aspects of the phylogeny of sex steroid binding plasma protein.

Sex steoid binding plasma protein (Sbp) in man and in monkeys binds the androgens dihydrotestosterone and testosterone and the estrogen estradiol with high affinity (Kd approximately 0.5, 1, and 2 nM, respectively). Detailed studies of steroid binding specificity give the same results in all primates, except that in humans and chimpanzees estrone does not compete for dihydrotestosterone binding. In other mammals, Sbps of Artiodactyla and Lagomorpha have the same range of affinities for androgens but they do not bind estradiol to any significant extent (Kd > 280 nM). The dog has an unusual Sbp (Kd for dihydrotestosterone, 7.1 nM; for estradiol, 125 nM), and rodents do not have a specific dihydrotestosterone-binding plasma protein. Gel filtration and immunoelectrophoretic experiments have been performed with a monospecific antiserum against human Sbp. The results indicate variable crossreactivities with Sbps of primates (from complete in chimpanzee and gorilla to weak in Prosimii). No crossreaction was observed with specific androgen-binding plasma proteins of other species. These results suggest the evolutionary emergence of bifunctional Sbp.

Animals↗
PubMed1986

Hemorrhage in lesions caused by cowpox virus is induced by a viral protein that is related to plasma protein inhibitors of serine proteases.

Several recombinant cowpox viruses were constructed and used to identify a viral gene that controls the production of hemorrhage in lesions caused by the Brighton Red strain of cowpox virus (CPV-BR). This gene is located in the KpnD fragment of CPV-BR DNA, between 31 and 32 kilobases from the end of the genome. This position corresponds well with that predicted from analyses of the DNA structures of spontaneously generated deletion mutants. The gene responsible for hemorrhage encodes a 38-kDa protein that is one of the most abundant early gene products. The 11-base-pair sequence GAAAATATATT present 84 base pairs upstream of its coding region is also present upstream of three other early genes of vaccinia virus; therefore, this sequence may be involved in the regulation of transcription. There is extensive similarity between the predicted amino acid sequence of the 38-kDa protein and the amino acid sequences of several plasma proteins that are inhibitors of various serine proteases involved in blood coagulation pathways. This suggests that the viral protein may possess a similar biological activity, which may enable it to effect hemorrhage by inhibiting one or more of the serine proteases involved in the host's normal processes of blood coagulation and wound containment.

Amino Acid Sequence↗
PubMed1982

[Characteristics of membrane and plasma proteins in the spontaneously hypertensive rat].

The red blood cell membrane proteins and plasma proteins of normal and spontaneous hypertensive Rats were studied by uni- and bidimentional polyacrylamide gel electrophoresis. The amount of band 3 was observed to be significantly reduced in the red blood cell membrane of spontaneously hypertensive Rats. Plasma from these Rats contained two additional heatstable proteins, characterized by a molecular weight of 16,000 dalton and isoelectric points of 4.7 and 5.1. These changes may constitute biochemical changes genetically associated with hypertension.

Animals↗
PubMed2001

Membrane insertion and lipid-protein interactions of bovine seminal plasma protein PDC-109 investigated by spin-label electron spin resonance spectroscopy.

The interaction of the major acidic bovine seminal plasma protein, PDC-109, with dimyristoylphosphatidylcholine (DMPC) membranes has been investigated by spin-label electron spin resonance spectroscopy. Studies employing phosphatidylcholine spin labels, bearing the spin labels at different positions along the sn-2 acyl chain indicate that the protein penetrates into the hydrophobic interior of the membrane and interacts with the lipid acyl chains up to the 14th C atom. Binding of PDC-109 at high protein/lipid ratios (PDC-109:DMPC = 1:2, w/w) results in a considerable decrease in the chain segmental mobility of the lipid as seen by spin-label electron spin resonance spectroscopy. A further interesting new observation is that, at high concentrations, PDC-109 is capable of (partially) solubilizing DMPC bilayers. The selectivity of PDC-109 in its interaction with membrane lipids was investigated by using different spin-labeled phospholipid and steroid probes in the DMPC host membrane. These studies indicate that the protein exhibits highest selectivity for the choline phospholipids phosphatidylcholine and sphingomyelin under physiological conditions of pH and ionic strength. The selectivity for different lipids is in the following order: phosphatidylcholine approximately sphingomyelin > or = phosphatidic acid (pH 6.0) > phosphatidylglycerol approximately phosphatidylserine approximately and rostanol > phosphatidylethanolamine > or = N-acyl phosphatidylethanolamine >> cholestane. Thus, the lipids bearing the phosphocholine moiety in the headgroup are clearly the lipids most strongly recognized by PDC-109. However, these studies demonstrate that this protein also recognizes other lipids such as phosphatidylglycerol and the sterol androstanol, albeit with somewhat reduced affinity.

Animals↗
PubMed1992

[Is platelet protein S different from plasma protein S in human being?].

Platelet suspension was obtained from normal platelet rich plasma (PRP) by the gel filtration method using Sepharose 2B and platelet pellet was prepared from the platelet suspension after centrifugation. A platelet preparation was prepared from the solubilized platelet pellet. Purified protein S was obtained from plasma and platelet preparation using immuno-affinity column chromatography. Total antigen of protein S was measured by enzyme immunoassay and activity of protein S was measured as a cofactor of activated protein C. The ratio of purified protein S activity to total antigen in normal plasma and platelet was 2.3 and 2.1, respectively. According to immunoblot and crossed immunoelectrophoresis studies, the molecular weight of platelet protein S was different from that of plasma protein S. Localization of protein S in platelet alpha-granules was demonstrated by immunoelectronmicroscopy.

Blood Platelets↗
PubMed1986

[Additive effects of protein malnutrition and cortisol on plasma proteins and immunoglobulins of pregnant rats, and their offsprings].

This research work was carried out to study the effects of two immunosuppressive mechanisms: protein malnutrition and cortisol treatment on the feto-maternal unit. Therefore, plasma Ig G and Ig M levels were tested in pregnant rats submitted to a low protein diet (4%) and cortisol treatment (0.5 mg/100 g b.w.) during pregnancy and in their offspring. Nutritional status was evaluated by measuring ponderal parameters and plasma protein levels in rat dams and their neonates. Thus, a fall in ponderal parameters and in plasma protein levels was observed, both in rat dams suffering protein malnutrition as well as in their newborns. Cortisol treatment produced a decrease in the ponderal parameters of the control group, and an increase in plasma protein levels of the malnourished one, both in rat dams and in their neonates. Apparently, protein malnutrition might lead to a low functionality of B lymphocytes, caused by a decrease in Ig G and Ig M rates of malnourished rat dams. Ig M levels, however, increased in neonates as a consequence of possible concomitant infections. Cortisol treatment promoted humoral immune deficiency, since Ig G and Ig M levels decreased both in the control and in the malnourished pregnant rat groups. Nevertheless, cortisol administration seemed to increase susceptibility to infection in the newborns, especially in those born from malnourished rat dams.

Animals↗
PubMed1989

Binding kinetics of tetrachloro-1,2-diaminocyclohexaneplatinum (IV) (tetraplatin) and cis-diamminedichloroplatinum (II) at 37 degrees C with human plasma proteins and with bovine serum albumin. Does aquation precede protein binding?

Experiments were conducted at 37 degrees C to study the kinetics of (a) binding of cis-diamminedichloroplatinum (II) (CDDP) and of a racemic mixture of d- and l-isomers of trans-tetrachloro-1,2-diaminocyclohexaneplatinum (IV) [or tetraplatin (TP)] to protein [human plasma proteins or bovine serum albumin (BSA)]; (b) aquation (acid hydrolysis) of CDDP and of TP; and (c) binding of charged (aquated) CDDP species to BSA. The experiments were performed at clinically relevant concentrations for CDDP, so that the proportional concentrations of platinum complexes relative to the concentrations of other chemical species in blood plasma were similar to those obtaining in the clinical use of the drug. "Free" (unbound) platinum complexes were separated from the protein-bound complexes were separated from the protein-bound complexes by gel filtration chromatography. By use of ion-exchange chromatography, charged platinum species were separated from the uncharged species and free charged platinum species of CDDP were separated from those bound to BSA. Platinum in various fractions was quantitated by atomic absorption spectrophotometry with electrothermal atomization; proteins were quantitated by te Bradford method with Coomassie blue dye. The kinetic data obtained by the application of these methods for CDDP are in good agreement with those obtained by other methods, e.g., binding rates based on separations by centrigugal ultrafiltration. The overall protein-binding reaction of CDDP was consistent with a binding process comprising two consecutive first-order reaction steps: the rate-controlling aquation reaction [half-life (t 1/2), approximately 2 hr] followed by a more rapid binding reaction of the charged (aquated) CDDP species to the protein (t 1/2, approximately 23 min). However, the results for TP indicated that prior aquation was not required for protein binding, and we could surmise that binding of TP to protein proceeds via a direct nucleophilic attack. An unexpected finding was the marked, reproducible difference in rates of aquation between the two lots of TP that we used; this finding suggests the need for cautions evaluation of pharmacokinetic data describing the behavior of TP.

Antineoplastic Agents↗
PubMed1977

The binding of drugs to plasma proteins and the interpretation of measurements of plasma concentrations of drugs in patients with poor renal function.

The intensity of a drug's action is related to its concentration in plasma water. Since the analytical methods for determining concentrations of drugs in plasma measure this as well as the drug bound to plasma proteins, evaluation of the binding of drugs to plasma proteins is needed for proper interpretation of drug level measurements. Anionic drugs have decreased binding in plasma from patients with renal failure. With some, such as phenytoin, a reduction is required in the levels usually considered "therapeutic" for uremic patients. Basic drugs may have normal or decreased binding. Propranolol, quinidine and tricyclic antidepressants are drugs in this class that have normal binding and that do not require changes in the plasma levels usually considered "therapeutic" for these patients.

Acute Kidney Injury↗
PubMed1980

Venoconstrictor activity of some precursor fractions of stable plasma protein solution.

Stable plasma protein solution (SPPS) is a 5% solution of human plasma albumin and some globulins. Rapid infusion of some batches of SPPS and analogous solutions prepared by similar processes induce paradoxical hypotensive reactions. In the current experiments, a number of precursor fractions of a single batch of SPPS were examined for kininogen content and for venoconstrictor activity on the isolated central vein of the rabbit ear. Unheated SPPS contained both venoconstrictor activity and kininogen. Among the various precursor fractions examined, Cohn fraction II + III (a precursor of fraction III-0) contained the greatest venoconstrictor activity. There was no evidence of kininogen depletion during the stages of fractionation examined but some generation of venoconstrictor material. Column chromatography suggested a molecular weight of approximately 1,500 for the major active material in unheated SPPS. It appears possible that the 14-amino acid hypotensive peptide present in fraction III-0 may also be present in SPPS, where it may contribute to the hypotensive effects of this solution.

Animals↗
PubMed1959

Depletion of reserve protein from extravascular extracellular fluid; C14 labeling of plasma proteins in dogs after plasmapheresis.

During protein depletion produced by plasmapheresis and a very low protein diet there is a proportionately greater decrease in extravascular, extracellular fluid protein than in plasma protein. A shift in the normal ratio of protein in these 2 compartments, approximately 1 to 1 in the dog, to over 2 to 1 as a result of depletion indicates an important, labile source of reserve protein for the plasma in the interstitial fluids. This reserve source is limited since a maximum drop of 50 per cent in the total exchangeable pool and of 75 per cent in the extravascular, extracellular protein occurred after both shorter and longer periods of depletion. Under the rigid conditions of these experiments additional plasma protein removal was associated with loss of weight despite adequate caloric intake. Investigation of the status of the interstitial fluid proteins in other conditions associated with disturbed protein metabolism seems warranted.

Animals↗
PubMed1984

A quantitative and qualitative study of the transglutaminase-mediated insertion of polyamines into plasma proteins from patients with bronchopulmonary cancer.

The transglutaminase-mediated incorporation of putrescine into proteins of plasma derived from 44 patients with histologically defined bronchopulmonary cancer was compared with that from an age-matched group of 18 patients hospitalized with non-malignant diseases. Two types of kinetic data were obtained over a range of putrescine concentrations 0.09 mM to 0.6 mM. Whereas the plasma from all the patients of the control group showed linear kinetics, that from only 24 patients of the cancer group showed linear kinetics. The remaining 20 showed kinetics typical of inhibition by excess substrate. PAGE analysis of [14C] putrescine-bound plasma proteins showed around 15 different bands. Among these putrescine-binding proteins, we identified, with the help of corresponding specific antisera, four protease inhibitors: alpha 2-macroglobulin, alpha 1-antitrypsin, alpha 1-antichymotrypsin and antithrombin III.

Acyltransferases↗
PubMed2000

Amyloid-beta peptides interact with plasma proteins and erythrocytes: implications for their quantitation in plasma.

Amyloid beta peptides are bound rapidly in the plasma complicating an accurate assessment of their in vivo abundance by immunoassay procedures. The extent of Abeta immunoassay interference was used to estimate the Abeta binding capacity of purified plasma proteins, erythrocytes and whole plasma. Human serum albumin bound Abeta peptides rapidly with a 1:1 stoichiometry and at physiological concentrations was capable of binding over 95% of an input of 5 ng/ml Abeta. Purified alpha2-macroglobulin was able to bind Abeta peptides and at physiological concentration bound 73% of 5 ng/ml of Abeta. Erythrocytes also sequestered the Abeta peptides, showing a preference for binding Abeta 1-42. Incubation of 5 ng/ml of Abeta in plasma revealed that about 30% of the peptides were still detectable by immunoassay, presumably reflecting the binding of Abeta peptides with albumin and other plasma molecules. Thus, our studies reveal that both the soluble and formed elements of the blood are capable of sequestering Abeta peptides. To avoid underestimating plasma Abeta values, we employed an improved column chromatography method under denaturing conditions to liberate Abeta from its associations with plasma proteins. Quantification of Abeta 40 and 42 levels in plasma from both normal and AD individuals after chromatography showed a large overlap between AD and control groups, despite the very large pool of Abeta present in the AD brains. The potential origins of the plasma Abeta pool are discussed.

Aged↗
PubMed1979

Effects of ethanol on plasma protein shedding in the human stomach.

Plasma protein shedding in the stomach was measured in 23 normal individuals before and after intragastric administration of a 30% solution of ethyl alcohol. Two different methods were used to assess plasma protein shedding. The first technique utilizes [131I]albumin and requires neutralization of the gastric juice. It was used in 12 subjects and failed to demonstrate any increase of plasma protein shedding under the influence of ethanol. The second technique which utilizes [51Cr]chloride was used in 11 subjects. It demonstrated a significant increase of the gastric clearance of plasma protein which reached 2.5 times the control values. The [51Cr]chloride technique does not require prior neutralization of gastric acidity. It is concluded that, in normal man, ethanol administration increases plasma protein shedding in the stomach when it is given in the presence of an acid gastric juice. The effect is not observed when the gastric acidity is neutralized.

Adult↗
PubMed1997

In vitro binding of MX2 (KRN8602) and epirubicin to human plasma protein.

This study compares the human plasma protein binding characteristics of MX2 and epirubicin. The binding characteristics were determined by equilibrium dialysis at various concentrations of the drugs. The binding dissociation constant (Kd), binding capacity (Bmax) and partitioning constant (Kp) were obtained by Scatchard analysis of the free and bound drugs in the dialysis compartments. Our results have demonstrated that plasma protein binds epirubicin or MX2 in an unsaturable appearance over the concentration up to 150 mumol/l. At the same concentrations, plasma protein binds more epirubicin than MX2. The nature of the interaction may consist of two classes of specific binding, and a partitioning. The binding dissociation constants were 18 and 17.5 mumol/l for the higher binding class (Kd1) and 315.8 and 316.9 mumol/l for the lower binding class (Kd2), respectively, for epirubicin and MX2. The respective maximum binding capacities (Bmax) of plasma protein for epirubicin and MX2 were significantly different, 0.045 and 0.029 mumol/g protein for the higher binding class (Bmax1), and 0.39 and 0.29 mumol/g protein for the lower binding class (Bmax2). The partitioning constants (Kp) were 21.5 x 10(-5) and 20 x 10(-5) litres/g protein for epirubicin and MX2, respectively. The results suggest that plasma protein binds epirubicin or MX2 with a similar affinity, but has less binding sites for MX2. One contributing mechanism to the difference in activity noted between epirubicin and MX2 may be changes in free drug fractions.

Antibiotics, Antineoplastic↗