Correlation between blood fibrinolytic activity, plasminogen activator inhibitor level, plasma insulin level, and relative body weight in normal and obese subjects

This study was undertaken to obtain further information on the mechanism by which blood fibrinolytic activity, a balance between plasminogen activators and inhibitors, is lowered in obese subjects. Fasting blood samples were collected from 35 subjects, aged 15 to 45 years, with normal glucose tolerance and a Body Mass Index (BMI) varying widely between 16 and 45 (normal, 19 to 25). Euglobulin Fibrinolytic Activity (EFA) did not correlate with the level of tissue type plasminogen activator (t-PA) related antigen but exhibited a negative correlation with the level of PA inhibitor (r = -.609, P less than 0.01). EFA was negatively and PA inhibitor positively correlated with both BMI (r = -.381, P less than 0.02 and .664, P less than 0.01, respectively) and plasma insulin level (r = .410, P less than 0.02 and .521, P less than 0.01, respectively). Stepwise analysis showed that these correlations were independent. As expected, plasma insulin was correlated with BMI (r = .512, P less than 0.01) and triglyceride level (r = .38, P less than 0.02), total cholesterol with age (r = .379, P less than 0.02). Ten obese subjects were submitted to a 24-hour fast. While body weight did not change appreciably, plasma insulin decreased from 22.3 +/- 2.2 to 16.3 +/- 1.1 microU/ml, EFA increased from 3.6 +/- .8 to 4.9 +/- .67 mm, and PA inhibitor decreased from 4.52 +/- .76 to 3.44 +/- .63 IU/mL. All these differences were significant. T-PA-related antigen did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Transport of steroid hormones through the rat blood-brain barrier. Primary role of albumin-bound hormone

These studies were undertaken to investigate (a) the permeability properties of the blood-brain barrier (BBB) to the major gonadal and adrenal steroid hormones, and (b) the role of the binding proteins of plasma (albumin and specific globulins) in the regulation of BBB steroid hormone transport. The permeability of the BBB to [(3)H]-labeled progesterone, testosterone, estradiol, corticosterone, aldosterone, and cortisol, was measured relative to [(14)C]butanol, a freely diffusable reference, in the barbiturate anesthetized rat using a tissue sampling-single injection technique. The isotopes were rapidly injected in a 200-mul bolus of Ringer's solution (0.1 g/dl albumin) via the common carotid artery and the percent extraction of unidirectional influx of hormone was determined after a single pass through brain: progesterone, 83+/-4%; testosterone, 85+/-1%; estradiol, 83+/-3%; corticosterone, 39+/-2%; aldosterone, 3.5+/-0.8%; and cortisol, 1.4+/-0.3%. The selective permeability of the BBB was inversely related to the number of hydrogen bonds each steroid formed in aqueous solution and directly related to the respective 1-octanol/Ringer's partition coefficient. When the bolus injection was 67% human serum, >95% of the labeled steroid was bound as determined by equilibrium dialysis. However, the influx of the steroids through the BBB was inhibited by human serum to a much less extent than would be expected if only the free (dialyzable) hormone was transported; progesterone, estradiol, testosterone, and corticosterone transport was inhibited 18, 47, 70, and 85% respectively, or in proportion to the steroid binding to plasma globulins. Rat serum (67%) only inhibited the transport of these four hormones, 0, 13, 12, and 69%, respectively, reflecting the absence of a sex hormone-binding globulin in rat plasma. However, neonatal rat serum (67%) inhibited progesterone, testosterone, and estradiol transport 0, 0, and 91%, respectively, consistent with the presence of an estradiol-binding protein in neonatal rat serum. The binding of steroid hormone to bovine albumin in vitro (as determined by equilibrium dialysis) was compared to albumin binding in vivo (as determined by the single injection technique). The ratio of apparent dissociation constant in vivo, K(D)(app), to the in vitro K(D) was: >>200 for progesterone, >200 for testosterone, 120 for estradiol, and 7.7 for corticosterone. Assuming the steady-state condition, the K(D)(app)/K(D) was found to be proportional to the BBB permeability for each steroid. These data demonstrate (a) the selective permeability properties of the BBB to the major steroid hormones is proportional to the tendency of the steroid to partition in a polar lipid phase and is inversely related to the number of hydrogen bond-forming functional groups on the steroid nucleus; (b) the presence of albumin in serum may bind considerable quantities of steroid hormone, but exerts little inhibitory effects on the transport of steroids into brain, whereas globulin-bound hormone does not appear to be transported into brain to a significant extent. Therefore, the hormone fraction in plasma that is available for transport into brain is not restricted to the free (dialyzable) fraction, but includes the larger albumin-bound moiety.

Melatonin ameliorates carbon tetrachloride-induced hepatic fibrogenesis in rats via inhibition of oxidative stress

Melatonin is reported to exhibit a wide variety of biological effects, including antioxidant and anti-inflammatory. Evidence shows the important role of oxidative stress in the etiopathogenesis of hepatic fibrosis. The aim of this study was to investigate the protective effects of administration of melatonin in rats with carbon tetrachloride-induced fibrosis for 6 weeks. Hepatic fibrotic changes were evaluated biochemically by measuring tissue hydroxyproline levels and histopathogical examinations. Malondialdehyde (MDA), an end product of lipid peroxidation, and glutathione peroxidase (GSH-px) and superoxide dismutase (SOD) levels were evaluated in tissue homogenates by spectrophotometry. The nuclear factor-kappaB (NF-kappaB) in liver tissue was examined by immunohistochemistry. Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) concentrations in Kupffer cells (KCs) culture supernatants were measured with ELISA. The rats injected subcutaneously with CCl4 for 6 weeks resulted in hepatic fibrotic changes increased hydroxyproline and MDA levels, and decreased GSH-px and SOD levels, whereas melatonin reversed these effects. Furthermore, melatonin inhibited the expression of NF-kappaB in liver tissue and decreasing production of proinflammatory cytokines such as TNF-alpha and IL-1beta from KCs in fibrotic rats. These present results suggest that melatonin ameliorates carbon tetrachloride-induced hepatic fibrogenesis in rats via inhibition of oxidative stress and proinflammatory cytokines production.

Serum globulin in myasthenia gravis: inhibition of alpha-bungarotoxin binding to acetylcholine receptors

Serum factors that inhibit the binding of (125)I-labeled alpha-bungarotoxin to the acetylcholine receptor extracted in detergent from denervated rat muscle were detected by a sensitive assay. The serum of at least 5 and possibly 11 out of 15 patients with myasthenia gravis showed inhibitory activity that was localized to the globulin fraction. No controls showed inhibitory activity. The demonstration of inhibitory globulins may help explain the involvement of the immune system in the pathophysiology of the neuromuscular junction in patients with myasthenia gravis.

A soluble androgen receptor in the cytoplasm of rat prostate

A thermolabile protein with the properties of a steroid 'receptor' was identified in the cytoplasmic or 105,000 g supernatant fraction of the rat prostate. The receptor has a particular binding specificity towards 5αdihydrotestosterone. Testosterone is bound to a lesser extent but other steroids, including certain androgenic hormones, are not bound. The sedimentation coefficient of 8·0 s and the frictional ratio of 1·96, equivalent to a molecular weight of 2·74 × 105, clearly distinguish the soluble androgen-receptor from the androgen-binding globulin in serum and the androgen-receptor in the prostatic nucleus. Like the nuclear receptor, however, the soluble receptor is probably an acidic protein. Both cysteine and tryptophan residues appear necessary for maintaining the functional configuration of the receptor.

Human leukocyte C1q receptor binds other soluble proteins with collagen domains

A receptor binding to the C1q subcomponent of complement has been reported by many workers. In this paper we report for the first time that C1q receptor binds not only to C1q, but also to three other structurally similar ligands, namely mannan binding protein (MBP), conglutinin, and lung surfactant protein (SP-A). All these ligands have been reported to enhance removal of species bound to their globular domain from blood (MBP, conglutinin, C1q) or lung (SP-A) through phagocytosis. One of the possible roles for ligand-receptor binding may be initiation of phagocytosis.

Role of kinins in the acute antihypertensive effect of the converting enzyme inhibitor, captopril

The role of kinins in the acute antihypertensive effect of a converting enzyme inhibitor (CEI) was studied in sodium-depleted normotensive and in two-kidney, one clip chronically hypertensive rats (2K-1C). The 2K-1C were on a normal sodium diet. The acute vasodepressor effect of the CEI was determined in these two groups either after administration of normal rabbit globulins or antikinin globulins. The amount of kinin antibodies administered completely blocked the hypotensive effects of bradykinin, 400 ng/kg, and urinary kallikrein, 4 microgram/kg. After administration of CEI in the sodium-depleted rats there was no significant difference (p greater than 0.05) in the acute changes in mean blood pressure (BP) between the group pretreated with normal rabbit globulins (delta BP -32.3 +/- 3.9 mm Hg) and the group pretreated with antikinin globulins (delta BP -25 +/- 2.5 mm Hg). In the 2K-1C pretreated with normal rabbit globulins, the CEI produced a decrease in BP of -21 +/- 4.5 mm Hg. This decrease was almost completely blocked in the group pretreated with the antikinin globulins (delta BP -4 +/- 4.1 mm Hg). These differences in the changes in BP were significant (p less than 0.02). These results suggest that the acute antihypertensive effect of the CEI in the sodium-depleted rats is probably due to inhibition of the conversion of angiotensin I to II while in the 2K-1C it is due, in part, to an increase in kinin concentrations secondary to the inhibition of kininase II.

Capillary transport of macromolecules: pores and other endothelial pathways

Can a pore or pore-equivalent model account for transport of macromolecules across microvascular endothelium, or are alternate nonpore pathways necessary? Pores may be defined as aqueous channels of any shape or configuration, including those through a fiber matrix. Such pathways exhibit selective restriction to passage of macromolecules depending on their size, shape, and electrical charge. At least two pore pathways (small and large), differing in both sieve-element spacing and in hydraulic conductivity by an order of magnitude, are required to account for observed size selectivity for plasma proteins of similar shapes and charges. For the two organs examined critically in this review (cat ileum and dog paw), transport of macromolecules through small and large pore pathways is predominately convective. Total transport through small and large pores (alternatively, narrow and wide slits or fine and coarse fiber matrices) is insufficient to account for observed transport rates at low-to-moderate levels of volume flow. Either the estimated pore sizes and hydraulic conductivities derived from measurements of high volume-flow sieving are incorrect or other nonconvective transport pathways contribute substantially to macromolecular transport at low (normal) volume flow.

Age related changes and interrelationships between plasma testosterone, oestradiol and testosterone-binding globulin in normal adult males

Testosterone (T), oestradiol-17β (Oe2) and binding capacity of the testosterone-binding globulin (TeBG) were measured in plasma of 84 adult males (22–90 years). The medians for age group I (22– 61 years, n = 50) were: T 545 ng/100 ml, Oe2 1.66 ng/100 ml, TeBG capacity 1.44 μg T/100 ml; the medians for age group II (67–90 years, n = 34) were: T 459 ng/100 ml, Oe2 2.56 ng/100 ml, TeBG capacity 2.05 μg T/100 ml. The decrease of T and the increase of Oe2 and TeBG capacity with age were significant. The significant correlation (P < 0.01) for either age group between T and Oe2 may be ascribed to a simultaneous secretion and/or a peripheral conversion of T to Oe2. The significant correlation (P < 0.05) between T and TeBG for the old age group probably reflects the comparatively high percentage of total plasma T bound to TeBG. The biological meaning of the correlation between Oe2 and TeBG is discussed.

Generation of three different fragments of bound C3 with purified factor I or serum. II. Location of binding sites in the C3 fragments for factors B and H, complement receptors, and bovine conglutinin

The many different recognized functions of C3 are dependent upon the ability of the activated C3 molecule both to bind covalently to protein and carbohydrate surfaces and to provide binding sites for as many as eleven different proteins. The location of the binding sites for six of these different proteins (factors B and H, complement receptors CR(1), CR(2) and CR(3) and conglutinin) was examined in the naturally occurring C3-fragments generated by C3 activation (C3b) and degradation by Factor I (iC3b, C3c, C3d,g) and trypsin (C3d). Evidence was obtained for at least four distinct binding sites in C3 for these six different C3 ligands. One binding site for B was detectable only in C3b, whereas a second binding site for H and CR(1) was detectable in both C3b and iC3b. The affinity of the binding site for H and CR(1) was charge dependent and considerably reduced in iC3b as compared to C3b. H binding to iC3b-coated sheep erythrocytes (EC3bi) was measurable only in low ionic strength buffer (4 mS). The finding that C3c-coated microspheres bound to CR(1), indicated that this second binding site was still intact in the C3c fragment. However, H binding to C3c was not examined. A third binding site in C3 for CR(2) was exposed in the d region by factor I cleavage of C3b into iC3b, and the activity of this site was unaffected by the further I cleavage of iC3b into C3d,g. Removal of the 8,000-dalton C3g fragment from C3d,g with trypsin forming C3d, resulted in reduced CR2 activity. However, because saturating amounts of monoclonal anti-C3g did not block the CR(2)-binding activity of EC3d,g, it appears unlikely that the g region of C3d,g or iC3b forms a part of the CR(2)-binding site. In addition, detergent-solubilized EC3d (C3d-OR) inhibited the CR(2)-binding activity of EC3d,g. Monocytes and neutrophils, that had been previously thought to lack CR(2) because of their inability to form EC3d rosettes, did bind EC3d,g containing greater than 5 x 10(4) C3d,g molecules per E. The finding that monocyte and neutrophil rosettes with EC3d,g were inhibited by C3d-OR, suggested that these phagocytic cells might indeed express very low numbers of CR(2), and that these CR(2) were detectable with EC3d,g and not with EC3d because C3d,g had a higher affinity for CR2 than did C3d. A fourth C3 binding site for CR(3) and conglutinin (K) was restricted to the iC3b fragment. Because of simultaneous attachment of iC3b to phagocyte CR3 and CR(3), the characteristics of iC3b binding to CR3 could only be examined with phagocytes on which the CR(1) had been blocked with anti-CR(1). Inhibition studies with EDTA and N-acetyl-D-glucosamine demonstrated a requirement for both calcium cations and carbohydrate in the binding of EC3bi to CR3 and to K. However, CR(3) differed from K in that magnesium cations were required in addition to calcium for maximum CR(3) binding activity, and NADG produced less inhibition of CR(3) activity than of K activity.

Thyroxine metabolism in the low thyroxine state of critical nonthyroidal illnesses

This study reports in vitro and in vivo parameters of T4 metabolism in patients with critical nonthyroidal illnesses who were selected because of serum total T4 values less than 3 micrograms/dl and normal TSH levels. Despite the depressed total T4 concentrations, the normal serum free T4 values (7 of 9 patients), T4 production rates (8 of 9), and TSH responses to TRH (8 of 8) provided evidence for normal free T4 availability to peripheral tissues. Elevated rT3 values in 10 of 14 patients were consistent with this view. However, serum free T4 index determinations markedly underestimated free T4 (20 of 20). This resulted from failure of the T3 uptake measurement to reflect the defective state of serum T4 binding. Defective serum T4 binding to carrier proteins was evidenced by the 2- to 3-fold increase in both the free fraction and the MCR values for T4. The normal early distribution phase, despite defective serum T4 binding, suggested an additional abnormality of deficient extravascular T4 binding. The blunted TSH response to TRH and the low normal values for both T4 production rates and free T4 levels measured by equilibrium dialysis indicated mild pituitary suppression, possibly related to elevated serum cortisol levels. Since an overt deficiency of free T4 availability does not appear to exist in the low T4 state of critical nonthyroidal illness, T4 therapy cannot currently be recommended.

Plasma MMP-9 (92 kDa-MMP) activity is useful in the follow-up and in the assessment of prognosis in breast cancer patients

Previously we determined that plasma MMP-9 activity was significantly elevated in breast cancer patients compared to benign mammary pathologies and healthy controls. Now we analyzed its potential usefulness in the follow-up and in the prognosis of these patients. MMP-9 activity was measured by gelatin quantitative zymography in the euglobulin plasma fraction of 46 breast cancer patients in a 38-month follow-up study. Blood samples were obtained before surgery (S1), 1 month after (S2) and every 3 months. The relapse-free survival (RFS) and overall survival (OS) analysis was performed along 56 months in 113 patients using the Kaplan-Meier curves and Cox analysis. In 63% of the S2 analyzed, MMP-9 decreased after surgery. In 44 patients evaluated during the adjuvant period who developed a complete response, MMP-9 decreased compared to their S1, whereas 2 patients showed an enhancement in correlation with lack of response. Further analysis indicated that in all patients who never showed evidence of recurrence, plasma MMP-9 activity remained low, but it increased 1 to 8 months preceding the clinical detection of progression in those patients who relapsed. Kaplan-Meier curves indicated that high levels of plasma MMP-9 activity at the moment of breast cancer diagnosis were associated with a worse OS rate. Cox analysis showed it was not associated with tumor stage or patient's age. Our results, which show a good correlation between plasma MMP-9 activity and the clinical status of each patient, suggest its usefulness as a marker both in the follow-up and in the prognosis of breast cancer patients.

Binding of testosterone and estradiol in plasma

It has been shown that the two major active sex hormones, estradiol and testosterone, are bound with high affinity to a common site (or sites) on plasma globulin. The level of this protein is elevated slightly in portal cirrhosis and greatly in the later months of pregnancy. The high specificity and affinity of this protein for the sex hormones has enabled it to be used to provide a sensitive radioassay for their determination in small amounts of body fluids.

Evidence for a renal calcium leak in postmenopausal women

We have measured calcium, albumin, globulin, bicarbonate, and anion gap in the plasma; and calcium, sodium, and creatinine in the urine, in 115 premenopausal and 140 postmenopausal normal women after an overnight fast, and calculated the calcium fractions in the plasma and the calcium/and sodium/creatinine ratios in the urine. The total ultrafiltrable calcium was significantly higher in the postmenopausal group, mainly due to their higher complexed calcium fraction, due in turn to their higher bicarbonate and anion gap concentrations. Urinary calcium was also significantly higher in the postmenopausal group even after correcting for sodium. After matching for total calcium and each of the calcium fractions in turn, the urinary calcium remained significantly higher in the post- than in the premenopausal sets even after correction for sodium. The implication is that the rise in urinary calcium at the menopause is due to reduced tubular reabsorption of calcium rather than to an increase in filtered load. We suggest that estrogens promote tubular reabsorption of calcium and that the rise in bone resorption at the menopause could be accounted for, at least in part, by the effect of estrogen deficiency on the kidney.

Two distinct serum mannose-binding lectins function as beta inhibitors of influenza virus: identification of bovine serum beta inhibitor as conglutinin

Normal bovine and mouse sera contain a component, termed beta inhibitor, that inhibits the infectivity and hemagglutinating activity of influenza A viruses of the H1 and H3 subtypes. We have previously shown these beta inhibitors to be mannose-binding lectins that apparently act by binding to carbohydrate on the viral hemagglutinin, blocking access of the receptor-binding site to receptors on host cells (E. M. Anders, C. A. Hartley, and D. C. Jackson, Proc. Natl. Acad. Sci. USA 87:4485-4489, 1990). For the H3-subtype virus A/Memphis/1/71 x A/Bel/42 (H3N1), sensitivity to beta inhibitors is determined by the oligosaccharide at residue 165 of the hemagglutinin, this glycosylation site being lost in a resistant mutant selected by growth in the presence of bovine serum. In the present study, we sequenced the hemagglutinin genes of additional bovine serum-resistant mutants derived from influenza viruses A/Philippines/2/82 (H3N2) and A/Brazil/11/78 (H1N1). The results confirm the importance of carbohydrate at residue 165 for inhibitor sensitivity of H3 viruses and implicate carbohydrate at residue 87 (94a in the H3 numbering system) as an important determinant in the sensitivity of H1-subtype viruses to the bovine inhibitor. Unlike the two H3 mutants, which had also gained resistance to hemagglutination inhibition by mouse serum, the H1 bovine serum-resistant mutant remained sensitive to the mouse beta inhibitor, suggesting that inhibition by the two types of sera is mediated by distinct mannose-binding lectins. In support of this hypothesis, the beta inhibitors in bovine and mouse sera were shown to differ in their pattern of inhibition by monosaccharides and in their sensitivity to 2-mercaptoethanol. In these and other properties, the bovine inhibitor closely resembled conglutinin, a Ca(2+)-dependent N-acetylglucosamine- and mannose-binding lectin present in bovine serum but absent from the serum of other species. Furthermore, polyclonal and monoclonal anticonglutinin antibodies abrogated the hemagglutination-inhibiting activity of bovine serum. Direct binding of conglutinin to the parent viruses and reduced binding to their respective mutants were confirmed by radioimmunoassay.

Transport of propranolol and lidocaine through the rat blood-brain barrier. Primary role of globulin-bound drug

Basic lipophilic drugs such as propranolol and lidocaine are strongly bound by alpha(1)-acid glycoprotein, also called orosomucoid. Although the liver is known to rapidly clear plasma protein-bound propranolol or lidocaine, it is generally regarded that peripheral tissues, such as brain or heart, are only exposed to the small fraction of drug that is free or dialyzable in vitro. The "free drug" hypothesis is subjected to direct empiric testing in the present studies using human sera and an in vivo rat brain paradigm. Serum from 27 human subjects (normal individuals, newborns, or patients with either metastatic cancer or rheumatoid arthritis) were found to have up to a sevenfold variation in orosomucoid concentrations. The free propranolol or lidocaine as determined in vitro by equilibrium dialysis at 37 degrees C varied inversely with the orosomucoid concentration. Similarly the rate of transport of propranolol or lidocaine through the blood-brain barrier (BBB) was inversely related to the existing serum concentration of orosomucoid. However, the inhibition of rat brain extraction of drug by orosomucoid in vivo was only about one-fifth of that predicted by free drug measurements in vitro. This large discrepancy suggested orosomucoid-bound drug was readily available for transport into brain in vivo. Studies using purified human orosomucoid in the rat brain extraction assay also showed that orosomucoidbound propranolol or lidocaine is readily transported through the BBB. Conversely, albumin-bound propranolol or lidocaine was not transported through the BBB. The studies using albumin provide evidence that the in vivo rat brain paradigm used in the present investigations is capable of confirming, when possible, predictions made by the "free drug" hypothesis. These data suggest that the amount of circulating propranolol or lidocaine that is available for transport into a peripheral tissue such as brain is not restricted to the free (dialyzable) moiety but includes the much larger globulin-bound fraction. Therefore, existing pharmacokinetic models should be expanded to account for the transport of protein-bound drugs into peripheral tissues similar to what is known to occur in liver.

Hypertriglyceridemia and regulation of fibrinolytic activity

A relation between elevated triglyceride (TG) levels and alterations of the fibrinolytic system has been recognized in studies of patients with coronary heart disease. In this investigation, the total fibrinolytic activity and the levels of specific components of the fibrinolytic system were evaluated in plasma samples from a highly selected group of patients with type IV hyperlipoproteinemia before and after a dietary treatment aimed at reducing TG levels. The fibrinolytic response of type IV patients was comparable to that of normolipidemic subjects, whereas tissue-type plasminogen activator antigen levels before and after venous occlusion (p less than 0.01) and resting plasminogen activator inhibitor-1 (PAI-1) antigen (p less than 0.01) and activity (p less than 0.01) were significantly higher in hypertriglyceridemic subjects compared with controls. After dietary treatment, a 22% reduction in TG levels was attained in type IV patients, with no appreciable modification of fibrinolytic parameters. The analysis of the single-patient data revealed a tendency toward normalization of PAI-1 levels only in those patients who showed a TG reduction greater than or equal to 20%. Very low density lipoproteins (VLDLs) from both normal and type IV patients concentration-dependently stimulated PAI-1 release by endothelial cells and HepG2 cells, with the effect of VLDL from type IV patients being more pronounced on HepG2 cells. The release of PAI-1 induced by VLDL in competent cells may thus account for the elevated levels of this antifibrinolytic protein that occur in hypertriglyceridemic patients.