Showing papers on "Serum albumin published in 1988"
TL;DR: From the slope of the regression line for adduct level as a function of intake, it was calculated that 1.4-2.3% of ingested AFB1 becomes covalently bound to serum albumin, a value very similar to that observed when rats are administered AFB1.
Abstract: Aflatoxin-serum albumin adducts in the blood of 42 residents of Guangxi Province, People's Republic of China, were determined and compared with intake of aflatoxin B1 (AFB1) and excretion of aflatoxin M1 (AFM1) in urine. Blood specimens were obtained during the same period that urine was collected and that diet was sampled. Serum albumin was isolated from blood by affinity chromatography on Reactive Blue 2-Sepharose and subjected to enzymatic proteolysis using Pronase. Immunoreactive products were purified by immunoaffinity chromatography and quantified by competitive radioimmunoassay. A highly significant correlation (r = 0.60, P less than 0.00003) of adduct level with AFM1 excretion was observed. An equally highly significant correlation of adduct level with intake (r = 0.69, P less than 0.000001) was also observed. From the slope of the regression line for adduct level as a function of intake, it was calculated that 1.4-2.3% of ingested AFB1 becomes covalently bound to serum albumin, a value very similar to that observed when rats are administered AFB1.
191 citations
TL;DR: The peripheral plasma levels of cholecystokinin (CCK) increased significantly during BSA but not during SPI or RS infusions, Thus, CCK levels were not increased by the inhibition of the proteolytic activity by RS in duodenal juice.
Abstract: The objective of this study was to investigate the effects of high and low inhibitor soybean meals on the duodenal enzyme activities and on the possible regulatory role of gastrointestinal hormones in the pancreatic response. After an overnight fast, 11 healthy volunteers received an intraduodenal infusion of saline for 60 min. This was followed by infusion of either of three test meals: extract of raw soybeans (RS), a low inhibitor soy protein isolate (SPI) or bovine serum albumin (BSA), 10 g/h for 60 min. Then saline was again given intraduodenally for 30 min. Gastric juice was collected continuously and duodenal juice and peripheral blood samples were collected every 10 min. Duodenal chymotryptic activity was severely inhibited by RS, whereas SPI and BSA increased the chymotryptic activity. Tryptic activity showed a transient reduction (55%) during RS infusion, whereas BSA and in particular SPI increased the tryptic activity. No change was seen in amylase activity. The lack of total inhibition of tryptic activity has been studied further and is the subject of the accompanying paper. The peripheral plasma levels of cholecystokinin (CCK) increased significantly during BSA but not during SPI or RS infusions. Thus, CCK levels were not increased by the inhibition of the proteolytic activity by RS in duodenal juice.
189 citations
TL;DR: Indoxyl sulfate was markedly accumulated in uremic serum, and inhibited drug binding, and was significantly increased in chronic hemodialysis patients and significantly but weakly correlated with the concentrations of creatinine and beta 2-microglobulin.
Abstract: We quantified indoxyl sulfate in uremic serum by using internal-surface reversed-phase high-performance liquid chromatography. Its concentrations were markedly increased in chronic hemodialysis patients, and were significantly but weakly correlated with the concentrations of creatinine and beta 2-microglobulin in these patients' serum, and with the duration of their hemodialysis treatment. Indoxyl sulfate could not be removed effectively by conventional hemodialysis because of its strong binding to serum albumin. Equilibrium dialysis demonstrated that indoxyl sulfate inhibited the binding of salicylate to albumin, and that 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid inhibited the binding of indoxyl sulfate to albumin. In conclusion, indoxyl sulfate was markedly accumulated in uremic serum, and inhibited drug binding.
180 citations
TL;DR: Results provide new information concerning those components of follicular fluid which may play a role in human sperm capacitation and provide further support for the concept that loss of cholesterol from the sperm plasma membrane is an important component of the capacitation process.
Abstract: The nature of cholesterol-binding proteins acting upon human spermatozoa during in vitro capacitation was determined by measuring the efflux of [3H]cholesterol and of [3H]cholesteryl sulfate from labeled spermatozoa. Efflux of [3H]sterols was stimulated when the labeled gametes were incubated in Ham's F-10 medium supplemented with female serum or follicular fluid. Upon centrifugation of capacitated spermatozoa and application of the supernatant to density-gradient ultracentrifugation for lipoprotein analysis, both [3H]cholesterol and [3H]cholesteryl sulfate were found to be carried by very-low-density lipoproteins (VLDL), low-density lipoproteins (VLDL), high-density lipoproteins (HDL), as well as the albumin fraction (d > 1.21) in serum. When the capacitation medium was supplemented with follicular fluid, the [3H]sterols were bound to HDL's and to the albumin fraction; when the latter fraction was analysed by molecular sieve chromatography, 60–70% of the radioactivity eluted in fractions with a mean molecular weight corresponding to that of human serum albumin. Sperm cholesterol efflux was also stimulated when serum or follicular fluid was added to a simplified medium (50 mM Tris-HCl, 0.56% NaCl, pH 7.8); efflux of [3H]cholesterol from labeled gametes progressed in a time-dependent manner, but was low in the absence of serum components. The [3H]cholesterol/cholesterol ratios were higher in the albumin and HDL fractions, indicating some degree of specificity of these sterol acceptors. It was observed that follicular fluid albumin has a [3H]sterol binding capacity that is 2—3-fold higher than that of serum albumin. Commercial human serum albumin also promoted sperm cholesterol efflux. These results provide new information concerning those components of follicular fluid which may play a role in human sperm capacitation and provide further support for the concept that loss of cholesterol from the sperm plasma membrane is an important component of the capacitation process.
165 citations
TL;DR: The present work on tumor vascular permeability has led to the following findings, which confirmed that kinin is generated via the kallikrein‐dependent cascade in the ascitic tumor fluid and blocked this kinin‐generating cascade with Kunitz‐type soybean trypsin inhibitor, and the formation of ascites was suppressed.
Abstract: Enhanced vascular permeability in tumor tissue has profound pathological consequences in tumor biology. However, details of the mechanism involved are not clear. The present work on tumor vascular permeability has led to the following three findings. (i) Ascitic tumor fluid contained kinin (about 1-40 ng/ml), which is known to enhance vascular permeability and induce pain in vivo. (ii) Kinin is generated via the kallikrein-dependent cascade in the ascitic tumor fluid. By blocking this kinin-generating cascade with Kunitz-type soybean trypsin inhibitor the formation of ascites was suppressed. (iii) Blocking of kinin-degrading enzymes (kininases I and II) by an appropriate kininase inhibitor (e.g., captopril) may result in increased permeability, leading to accumulation of the ascitic fluid. This phenomenon was verified by an about 1.2-1.5 fold increase in leakage of 51Cr-labeled bovine serum albumin into the ascites when kininase inhibitors had been administered orally 30 min before intravenous administration of the bovine serum albumin.
150 citations
TL;DR: Findings indicate that the 60-kDa glycoprotein is directly involved in a specific interaction of albumin with the cultured microvascular endothelial cells used in these experiments.
Abstract: Confluent monolayers of microvascular endothelial cells, derived from the rat epididymal fat pad and grown in culture, were radioiodinated by using the lactoper-oxidase method. Their radioiodinated surface polypeptides were detected by NaDodSO4/PAGE (followed by autoradiography) and were characterized by both lectin affinity chromatography and protease digestion to identify the proteins involved in albumin binding. All detected polypeptides were sensitive to Pronase digestion, whereas several polypeptides were resistant to trypsin. Pronase treatment of the cell monolayer significantly reduced the specific binding of radioiodinated rat serum albumin, but trypsin digestion did not. Limax flavus, Ricinus communis, and Triticum vulgaris agglutinins competed significantly with radioiodinated rat serum albumin binding, whereas other lectins did not. A single 60-kDa glyco-protein was precipitated in common by these three lectins and was trypsin-resistant and Pronase-sensitive. Rat serum albumin affinity chromatography columns weakly but specifically bound a 60-kDa polypeptide from cell lysates derived from radioiodinated cell monolayers. These findings indicate that the 60-kDa glycoprotein is directly involved in a specific interaction of albumin with the cultured microvascular endothelial cells used in these experiments.
148 citations
TL;DR: In the presence of plasma, IL-1-inducing factors pass into the blood compartment of a dialysis system challenged with bacterial pyrogen; and in vitro MNC production ofIL-1 is enhanced in the absence of plasma.
140 citations
TL;DR: The results suggest that fatty acids act as simple (A− type) proton carriers in phospholipid bilayer membranes containing long-chain fatty acids, which may cause significant biological H+ conductance when present in the membrane at high concentrations.
Abstract: Mechanisms of proton conductance (GH) were investigated in phospholipid bilayer membranes containing long-chain fatty acids (lauric, myristic, palmitic, oleic or phytanic). Membranes were formed from diphytanoyl phosphatidylcholine in decane plus chlorodecane (usually 30% vol/vol). Fatty acids were added either to the aqueous phase or to the membrane-forming solution. Proton conductance was calculated from the steady-state total conductance and the H+ diffusion potential produced by a transmembrane pH gradient. Fatty acids caused GH to increase in proportion to the first power of the fatty acid concentration. The GH induced by fatty acids was inhibited by phloretin, low pH and serum albumin. GH was increased by chlorodecane, and the voltage dependence of GH was superlinear. The results suggest that fatty acids act as simple (A- type) proton carriers. The membrane: water partition coefficient (Kp) and adsorption coefficient (beta) were estimated by finding the membrane and aqueous fatty acid concentrations which gave identical values of GH. For palmitic and oleic acids Kp was about 10(5) and beta was about 10(-2) cm. The A- translocation or "flip-flop" rate (ka) was estimated from the value of GH and the fatty acid concentration in the membrane, assuming that A- translocation was the rate limiting step in H+ transport. The kA's were about 10(-4) sec-1, slower than classical weak-acid uncouplers by a factor of 10(5). Although long-chain fatty acids are relatively inefficient H+ carriers, they may cause significant biological H- conductance when present in the membrane at high concentrations, e.g., in ischemia, hypoxia, hormonally induced lipolysis, or certain hereditary disorders, e.g., Refsum's (phytanic acid storage) disease.
131 citations
TL;DR: Effects of Staphylococcus aureus alpha-toxin and Pseudomonas aeruginosa cytotoxin on the permeability of an endothelial monolayer were studied and changes in permeability were accompanied by cell retraction and formation of large intercellular gaps between endothelial cells.
Abstract: Effects of Staphylococcus aureus alpha-toxin and Pseudomonas aeruginosa cytotoxin on the permeability of an endothelial monolayer were studied. Porcine pulmonary artery endothelial cells were grown on a polycarbonate membrane, mounted in a chamber, and exposed to a continuous hydrostatic pressure of 10 cmH2O. On application of this trans-endothelial pressure, endothelial monolayer became "sealed," i.e., the filtration rate for water decreased and the reflection coefficient for albumin increased, reaching a plateau after 1-2 h. Sealed monolayer had a hydraulic conductivity of 2.1 X 10(-6) cm.s-1.cmH2O and an albumin reflection coefficient of 0.73. Permeability of the monolayer was increased on addition of an excess of EDTA and reversed on readdition of calcium. Within 60-90 min after addition of 1 microgram/ml alpha-toxin, the filtration rate increased 75-fold, and the albumin reflection coefficient dropped to 0.20. These changes in permeability were accompanied by cell retraction and formation of large intercellular gaps between endothelial cells. Effects of alpha-toxin were abolished by preincubation with neutralizing antibodies and by inhibitors of calmodulin function. Pseudomonas aeruginosa cytotoxin (25 and 50 micrograms/ml) also increased the permeability of the endothelial monolayer, but it was only about one-third as effective as alpha-toxin.
129 citations
TL;DR: Serum albumin is the simplest and best single predictor of mortality and can provide early identification of elderly people at increased risk of death.
127 citations
TL;DR: Three distinct types of behaviour concerning the adsorption of albumin on to metal surfaces were identified and it is suggested that electrostatic forces could be responsible for this phenomenon.
TL;DR: It is concluded that the facilitation of nonheme Fe absorption by meat is not a general property of all animal protein but is better explained by the action of one or more specific animal tissues.
TL;DR: It is found that long-chain bases possess potent inhibitory properties which make them useful probes of signal transduction mechanisms, and data indicate an inhibitory effect subsequent to the generation of second messengers and are consistent with protein kinase C as the locus of action.
TL;DR: The data demonstrate that hypoalbuminemia is not a consequence of normal aging, and a multivariate model of cross-sectional data can explain only 5% of the variance.
Abstract: To clarify the relation between age and serum albumin, measures were obtained on a screened population of 1066 healthy males in the Normative Aging Study. Multiple regression analysis shows only a slight decline in albumin of 0.054 gm/dl per decade with R = -0.12 (p less than .001) on cross-sectional data. This small decline occurs entirely within the range of normal, contrary to many previous reports. Mean albumin values were 4.25 (+/- .26 SD) for subjects in the eighth decade and 4.13 (+/- .29 SD) in the ninth decade. Longitudinally, there was an upwards trend in albumin for five birth cohorts over an 8-yr period which may reflect laboratory drift. A multivariate model of cross-sectional data can explain only 5% of the variance. The age-related decline within healthy subjects is far less than previously described. Our data demonstrate that hypoalbuminemia is not a consequence of normal aging.
Patent•
25 Oct 1988TL;DR: In this article, the use of mature human serum albumin residues 1 to n, where n is between 369 and 419 inclusive, are useful as substitutes for albumin in the treatment of burns and shock in humans, the clearances of undesirable compounds, such as bilirubin from human blood, in laboratory growth media and in HSA assays.
Abstract: Polypeptides corresponding to mature human serum albumin residues 1 to n, where n is between 369 and 419 inclusive, are useful as substitutes for albumin in the treatment of burns and shock in humans, the clearances of undesirable compounds, (such as bilirubin) from human blood, in laboratory growth media and in HSA assays. HSA (1-389) is particularly preferred, although not novel per se. The polypeptides may be produced by recombinant DNA techniques, especially in yeast.
TL;DR: A highly reproducible in vivo model in which hepatocytes are induced in the pancreas of adult rats that were maintained on copper-deficient diet containing a relatively non-toxic copper-chelating agent, triethylenetetramine tetrahydrochloride (0.6% w/w) for 7-9 weeks and then returned to normal rat chow is described.
TL;DR: It was hypothesized that because 5% human albumin, when sonicated for use as a contrast agent, is neither hyperosmolar nor a calcium chelator, it would not have significant effects on coronary blood flow, left ventricular function or systemic hemodynamics.
TL;DR: Increasing serum albumin concentrations with NSA in hypoalbuminemic patients receiving central TPN appears to be associated with a reduction in hospital morbidity.
Abstract: Because several studies have shown a significant inverse correlation between depressed serum concentrations of albumin and hospital morbidity, a study with central total parenteral nutrition (TPN) with normal serum albumin (NSA) in hypoalbuminemic patients was conducted. Sixty-one patients who required central TPN were randomized into one of two groups: group 1 (n = 31) received TPN plus NSA (25 to 37.5 g/day) until their measured serum albumin was greater than 3 g/dl, and group 2 (n = 30), who received TPN alone. All patients were followed for hospital complications until discharge or death. The groups were well matched for age, sex, major diagnoses, initial serum albumin concentrations, hospital complications before TPN, and number of operative procedures. Both groups received comparable doses of energy (37.2 +/- 89 vs. 3.30 +/- 6.2 kcal/kg.day) and protein (1.6 +/- 0.4 vs. 1.6 +/- 0.3 g/kg.day). After initiation of TPN, there were significantly more hospital complications in group 2 (1 = 1.1 +/- 1.4, n = 33; 2 = 2.6 +/- 3.0, n = 80, p less than .01). When complications in the patient groups were stratified, significantly more patients in group 2 developed pneumonia (18 vs. 9, p less than .05) and septicemia (11 vs. 2, p less than .05). Increasing serum albumin concentrations with NSA in hypoalbuminemic patients receiving central TPN appears to be associated with a reduction in hospital morbidity.
TL;DR: The study indicated that the increase of extracellular osmotic pressure due to leakage of serum proteins via the disrupted BBB and of intracellular substances via the ischemically injured cell membrane into the extacellular space is the mechanism responsible for edema fluid accumulation in exacerbated ischemic brain edema.
Abstract: The mechanism of exacerbation of ischemic brain edema after blood flow restoration was studied in 20 cats under ketamine and alpha-chloralose anesthesia. Regional cerebral blood flow was measured by the hydrogen clearance method, and the left middle cerebral artery (MCA) was occluded for 6 h in group A, and for 3 h with subsequent 3 h recirculation in group B. Severity of brain edema was assessed by specific gravity measurement of tissue samples taken from coronal brain sections at the MCA area, while severity of blood-brain barrier (BBB) disruption was determined by measuring the amount of extravasated serum albumin by using [125I]albumin and tissue-uptake method in the same samples as those used for gravimetry. Structural and ultrastructural change was correlated with the severity of ischemic brain edema and BBB disruption. The results obtained showed that: (i) ischemic brain edema observed in group A was not associated with BBB opening to serum proteins; (ii) ischemic edema in group B was exacerbated significantly after recirculation in correlation with serum protein extravasation in most of the postischemic area; (iii) in the severely edematous area, serum protein extravasation reached a plateau and morphological examination at this type of area revealed cell membrane disruption especially of astrocytes, with leakage of intracellular substances. Our study indicated that the increase of extracellular osmotic pressure due to leakage of serum proteins via the disrupted BBB and of intracellular substances via the ischemically injured cell membrane into the extracellular space is the mechanism responsible for edema fluid accumulation in exacerbated ischemic brain edema.
TL;DR: A strong correlation was found between cell uptake and distribution into octanol, and none of the other factors could be correlated with cell uptake.
Abstract: — For a variety of chemically defined, synthetic and natural porphyrins, the tendency for self aggregation, binding to serum albumin, distribution coefficient betweenoctanol–1 and water and uptake in V79 Chinese hamster cells have been determined. A strong correlation was found between cell uptake and distribution into octanol. None of the other factors could be correlated with cell uptake. These observations might have an impact on the use of porphyrins in photodynamic and boron neutron capture therapy of tumors.
TL;DR: The specific binding of rat serum albumin to confluent microvascular endothelial cells in culture derived from the vasculature of the rat epididymal fat pad was studied by radioassay and immunocytochemistry and dissolution rate analysis supports negative cooperativity of albumin binding.
Abstract: The specific binding of rat serum albumin (RSA) to confluent microvascular endothelial cells in culture derived from the vasculature of the rat epididymal fat pad was studied at 4 degrees C by radioassay and immunocytochemistry. Radioiodinated RSA (125I-RSA) binding to the cells reached equilibrium at approximately 20 min incubation. Albumin binding was a slowly saturating function over concentrations ranging from 0.01 to 50 mg/ml. Specific RSA binding with a moderate apparent affinity constant of 1.0 mg/ml and with a maximum binding concentration of 90 ng/cm2 was immunolocalized with anti-RSA antibody to the outer (free) side of the endothelium. Scatchard analysis of the binding yielded a nonlinear binding curve with a concave-upward shape. Dissociation rate analysis supports negative cooperativity of albumin binding, but multiple binding sites may also be present. Albumin binding fulfilled many requirements for ligand specificity including saturability, reversibility, competibility, and dependence on both cell type and cell number. The results are discussed in terms of past in situ investigations on the localization of albumin binding to vascular endothelium and its effect on transendothelial molecular transport.
TL;DR: H2.35 cell line from mouse hepatocytes infected with a temperature-sensitive strain of simian virus produces cells that exhibit extremely low levels of albumin transcription and mRNA, and an induction of transcription is caused by activation of an albumin upstream sequence that was previously shown to enhance liver-specific transcription in transgenic mice.
Abstract: We sought to develop a cell line in which liver-specific transcription could be induced at will, to facilitate the study of factors that cause hepatocyte-specific transcription of the serum albumin gene in mice. We therefore created the H2.35 cell line from mouse hepatocytes infected with a temperature-sensitive strain of simian virus 40. During routine propagation at the permissive temperature, H2.35 cells exhibit extremely low levels of albumin transcription and mRNA. Albumin mRNA increases at least 100-fold when H2.35 cells are cultured at the restrictive temperature and in serum-free medium on a collagen substratum; the two latter conditions maintain the differentiated state of primary hepatocyte cultures. Although a major cause of the mRNA increase is posttranscriptional, the transcription rates of albumin and other liver-specific genes increase significantly. Transient-transfection experiments demonstrated that an induction of transcription is caused by activation of an albumin upstream sequence that was previously shown to enhance liver-specific transcription in transgenic mice. Thus, hepatocyte differentiation appears to be maintained in part by extracellular signals that stimulate the activity of a tissue-specific enhancer element.
Journal Article•
TL;DR: The rapid intracarotid injection technique was used to determine the unidirectional brain uptake of a number of benzodiazepines in the rat and the observed brain extraction was greater than predicted, and the discrepancy became more apparent as binding and albumin concentration increased.
Abstract: The rapid intracarotid injection technique was used to determine the unidirectional brain uptake of a number of benzodiazepines in the rat. The drugs varied considerably in their lipophilicity and, within the series oxazepam, lorazepam, chlordiazepoxide, desmethyldiazepam and diazepam, brain extraction of unbound moiety was enhanced as the octanol-water (pH = 7.4) partition coefficient increased. However, with flunitrazepam and midazolam, two fluorine-containing benzodiazepines, extraction was more and less extensive, respectively, than predicted from their lipophilicities. Importantly, the uptake findings were consistent with the characteristic onsets of central effects of the drugs established clinically in humans. The effects of reversible protein binding on uptake also were investigated by the addition of albumin (0-8 g.dl-1) to the injectate. This affected markedly the unbound fraction, determined in vitro by equilibrium dialysis, and also the brain uptake of all drugs. As the unbound fraction was reduced, the unidirectional brain extraction ratio decreased in a curvilinear fashion toward zero. However, attempts to describe the data were unsuccessful using a conventional model based on transcapillary uptake of only unbound drug whose binding kinetics with albumin were assumed to be the same as those indicated by equilibrium dialysis. The observed brain extraction was greater than predicted, and the discrepancy became more apparent as binding and albumin concentration increased. The data for all of the benzodiazepines could be fitted, however, if the equilibrium association constant was assumed to be smaller in vivo than in vitro, so that the effective unbound fraction in the brain capillaries was substantially higher (5- to 25-fold, dependent on the particular drug) than that estimated in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: A technique for determining the amount of thermally denatured, insoluble protein is described, which can measure protein concentrations as small as 10 micrograms, typically with standard deviations of 3%, thus comparing favorably with the standard Bradford assay.
TL;DR: In this paper, the primary warfarin binding site is located in domain two of the albumin structure and domain one plays an important role in the N-B transition of albumin.
TL;DR: The results indicate that the fructosamine assay measures the extent of glycation of purified human serum albumin correctly and is of limited specificity for the exact measurement of glycated proteins in serum.
Abstract: We compared the fructosamine activity in sera from healthy and diabetic subjects with the degree of protein glycation detected by a liquid-chromatographic method. The latter technique measures furosine as a specific product after hydrolysis of epsilon-amino-fructose-lysine. Our results indicate that the fructosamine assay measures the extent of glycation of purified human serum albumin correctly. On the other hand, we found no correlation between the two methods for sera from healthy subjects, although for diabetics' sera the values obtained with both methods were related. However, only about half of the reducing activity (fructosamine) was due to specific nonenzymatic glycation of proteins in healthy subjects and well-controlled diabetics. The remaining unspecific activity varied from serum to serum. It was not reducible with NaBH4 and was independent of the glycation of albumin, which normally accounts for about 80% of glycated serum proteins. The fructosamine assay is therefore of limited specificity for the exact measurement of glycated proteins in serum.
TL;DR: To examine whether its monophosphate ester (ara-AMP) can be effective in the treatment of chronic hepatitis B when given in reduced dosage as a conjugate with lactosaminated human serum albumin (L-HSA), which selectively enters hepatocytes, five patients with chronic type B hepatitis were treated with the conjugates.
TL;DR: Results show the presence of a cell population in the rat kidney that actively transcribes both the albumin and AFP genes, which may be mediated by mechanisms differing in at least some steps from those exerted in the liver.
TL;DR: Compared highly purified NC, THP, and albumin adsorption with COM crystals and CG inhibition; also their patterns of cross-reactivities with a new antiserum against NC and a monoclonal antibody to THP are compared.
Abstract: Urine inhibition of calcium oxalate monohydrate (COM) crystal growth (CG) seems due to a glycoprotein that contains gamma-carboxyglutamic acid and has been named nephrocalcin (NC); however, Tamm-Horsfall protein (THP) and albumin resemble NC and make its measurement and role uncertain. NC in urine is aggregated to molecular mass 64 kDa and higher, similar to albumin (64 kDa) and THP (87 kDa). Albumin and THP are calcium binding, albumin adsorbs to COM crystals, and THP has been described as an inhibitor of COM growth. Antisera to NC have cross-reacted with THP even though the NC was isolated from cultured renal cells. Here we have compared highly purified NC, THP, and albumin adsorption with COM crystals and CG inhibition; also we compared their patterns of cross-reactivities with a new antiserum against NC and a monoclonal antibody to THP. NC adsorbs to COM crystals, THP does not. Albumin and THP do not inhibit CG. Cross-reactivity of albumin and THP to the antiserum is slight by direct enzyme-linked immunosorbent assay and nonexistent by competitive ELISA; reaction of NC to the anti-THP monoclonal antibody is absent.
TL;DR: Most of the increased plasma CRH found in pregnant women is bound to CRH-BP, and so is inactive, therefore plasma ACTH levels do not increase to above the normal range.
Abstract: A human plasma CRH-binding protein (CRHBP) was identified and characterized by chemical cross-linking of 125I-Tyr-hCRH to human plasma using disuccinimidyl suberate. The apparent mol wt of the cross-linked complex determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography was approximately 43,000. The mol wt was slightly lower in the nonreduced state, suggesting the presence of intramolecular disulfide bonds. Subtracting the mol wt of 125I-Tyr-CRH, the BP appeared to have a mol wt of approximately 38,000. Binding was specific since the appearance of the 43,000 dalton band was not affected by unlabeled ACTH, vasopressin, serum albumin, or γ-globulin, but was inhibited by unlabeled hCRH dose dependently. Pretreatment of plasma with 0.1 mol/L HC1, 0.01 mol/L NaOH, 10 mmol/L dithiothreitol, or trypsin before cross-linking abolished its ability to bind 125I-Tyr-hCRH. Rat, rabbit, or goat plasma or human cerebrospinal fluid did not bind 125I-Tyr-CRH. It is unlikely that ...