Modulation by 310-1310-1310-1stimulation of IgE-mediated14C-serotonin release from rat mast cells

The formaldehyde method was used to examine the effects of clonidine and methoxamine on IgE-mediated¹⁴C-serotonin release from rat mast cellsin vitro. Clonidine (10^?11?10^?8 M) caused dose-related enhancement of the mediator release 7min after the antigen challenge yohimbine (10^?6 M) blocked this enhancement by clonidine (10^?6 M), but prazosin (10^?6 M) did not. Methoxamine did not enhance this immunological release reaction at concentrations up to 10^?6 M. PGE₁ (2×10^?8?2×10^?5 M), isoproterenol (10^?10?10^?8 M), dopamine (4×10^?8?4×10^?8 M) and aminophylline (6×10^?6?6×10^?4 M) caused dose-related inhibition of this mediator release 1 min after antigen challenge. Clonidine (10^?13?10^?12 M), but not methoxamine (10^?8?10^?6 M), reversed dose-dependently this inhibition of mast cells by PGE₁ (2×10^?6 M), isoproterenol (10^?8 M), dopamine (4×10^?6 M); yohimbine (10^?8 M) antagonized this reversing action of clonidine (10^?12 M), but prazosin (10^?10 M) did not. Neither clonidine (10^?14?10^?11 M) nor methoxamine (10^?8?10^?6 M) reversed the inhibitory action of aminophylline (2×10^?4 M). These results suggest that clonidine enhances IgE-mediated¹⁴C-serotonin release from rat mast cells and also antagonizes the inhibition of mast cells by PGE₁, isoproterenol and dopamine, but not by aminophylline in this immunological reaction through α₂-adrenergic receptors, and that the inhibition of adenylate cyclase of mast cells is one of the biochemical actions of α₂-adrenergic mechanisms.     

Human Fetal/Neonatal Suppressor Activity: Relation Between OKT Phenotypes and Sensitivity to Prostaglandin E2 in Maternal and Neonatal Lymphocytes

ABSTRACT: T lymphocytes from human fetuses and newborns strongly and spontaneously suppress various adult cell functions (i.e. T-cell proliferation, B-cell differentiation, and Ig synthesis). The precise phenotype of the suppressor cell is controversial. In this investigation we use cord T-cell subsets negatively selected by the panning technique or by complement-mediated lysis using the monoclonal antibodies OKT4 and OKT8. Cord T cells deprived of the OKT4⁺ subpopulation exerted only a marginal suppressor activity (12 ± 7 as compared to 73 ± 4% of unfractionated T cells) on the proliferation of maternal cells in our PHA-stimulated co-culture assay using sex chromosomes as markers for dividing cord (male) and maternal cells. The suppressive effect was direct, i.e. not mediated by induction of maternal OKT8⁺ suppressor effector cells. Cord and maternal T-cell subsets were also tested for their sensitivity to exogenous prostaglandin E₂ (PGE₂) at doses varying between 1.4 × 10^?5 and 1.4 × 10^?9 M. Both maternal OKT4^? and OKT8^? T-cell subsets were highly sensitive to suppression by PGE₂. In contrast, cord OKT8^? T cells were essentially nonsensitive at all doses of PGE₂ used, whereas cord OKT4^? T cells were significantly suppressed at four out of five concentrations tested (1.4 × 10^?6 through 1.4 × 10^?9). Our results suggest a direct correlation between the phenotypes of the cord-suppressor and maternal-target T cells and their sensitivity to PGE₂.     

<Emphasis Type="Italic">In vitro</Emphasis> effects of hyaluronan on prostaglandin E<Subscript>2</Subscript> induction by interleukin-1 in rabbit articular chondrocytes

Effects of hyaluronan (HA) on the prostaglandin E₂ (PGE₂) production induced by recombinant human interleukin-1β (rhIL-1β) in rabbit articular chondrocytes were studiedin vitro. The rhIL-1β-induced PGE₂ production was dose-dependently inhibited by HA. HA with the highest molecular weight (M_r=2.0×10⁶) exhibited an inhibitory effect that was statistically more significant than the same polymer of lower molecular weights (M_r=1.0×10⁶, 0.5×10⁶). This effect was observed in both young and adult rabbit articular chondrocytes. Since PGE₂ has been implicated as a mediator of inflammatory joint diseases, our observations suggest that HA may elicit an anti-inflammatory effect by inhibiting PGE₂ production.     

Structural requirements for recognition of vasopressin by antibody; Thermodynamic and kinetic characteristics of the interaction

The thermodynamic and kinetic properties of two conventional antivasopressin antisera were studied. Values for binding affinity were determined by equilibrium measurements to be Kd = 1.4 and 2.7 × 10^?12M. The kinetic parameters were independently determined. The association rate constants (kas) were calculated by a pseudo-first-order analysis of binding kinetics (ka = 3.1 and 1.7 × 10⁷M^?1 sec^?1). The dissociation rate constants (kds) were measured by dissociating antibody-labelled antigen complexes with large excess of unlabelled antigen (kd = 1.6 and 1.7 × 10^?5 sec^?1). A fairly close agreement was achieved between equilibrium and kinetic evaluation of the affinity.The heterogeneity cannot be assessed through equilibrium experiments because of the very low concentrations of reagents to be handled. However, kinetic studies strongly suggested that the molecular heterogeneity with respect to affinity of the antisera is restricted to a narrow range (5 × 10^?13M to 7 × 10^?12M).Despite their very similar physicochemical properties these two antisera exhibited different fine specificities: the study of cross-reactivities with various analogues of the original hapten showed that one antiserum—5—is clearly directed against the C-terminal moiety of the molecule. The antigenic determinant is a sequential one and composed of the last four aminoacids Cys-Pro-Arg-GlyNH₂, while the other antiserum is not so sensitive to modifications of the last residue GlyNH₂.     

Direct quantitative measurement of the kinetics of HLA-specific antibody interactions with isolated HLA proteins

HLA specific antibodies vary in their pathogenicity and this is likely to be the net effect of constant chain usage, quantity, specificity, and affinity. Here we have measured the affinity of human monoclonal antibodies for a range of HLA proteins. Purified antibodies and ligands allowed dynamic interactions to be measured directly by surface plasmon resonance. Physiochemical differences between pairs of ligands were quantified using electrostatic mismatch and hydrophobic mismatch scores.All antibodies were characterized by fast on-rates and slow off rates but with a wide range of association rates (k_on, 3.63–24.25?×?10⁵ per mol per second) and dissociation rates (k_off, 0.99–10.93?×?10^?3 per second). Dissociation constants (K_D) ranged from 5.9?×?10^?10?M to 3.0?×?10^?8?M. SN320G6 has approximately a twenty-fold greater affinity for HLA A2 compared with SN607D8, but has a similar affinity for HLA-A2 and B57. In contrast, SN607D8 has greater than a twofold greater affinity for HLA-A2 compared with A68. Similarly, WK1D12 has about a threefold greater affinity for HLA-B27 compared with B7. The higher affinity interactions correlate with the specificity of stimulating antigen. This is the first study to directly measure the binding kinetics and affinity constants for human alloantibodies against HLA.     

Strong Suppression by Mononuclear Leukocytes From Cord Blood of Human Newborns on Maternal Leukocytes Associated With Differences in Sensitivity to Prostaglandin E2*

ABSTRACT: We have tested peripheral mononuclear leukocytes (PML) from the cord blood of newborns, from sera of their mothers, and from sera of nonrelated nonpregnant adult women for sensitivity to suppressive exogenous prostaglandin E₂ (PGE₂). Endogenous PG production was simultaneously inhibited by indomethacin 2.8 μM. The phytohemagglutinin-stimulated (PHA-stimulated) uptake of tritiated thymidine (³H-TdR) by PML from the mothers and the nonpregnant women was suppressed by the exogenous PGE₂ at a concentration of 1.4 × 10^?8 M, 100 times less than the one required to suppress the PML from newborns (1.4 × 10^?6 M). In addition, 1.4 × 10^?7 M or less of PGE₂ reversed the suppression of neonatal PML to stimulation. The maternal PML were reversed into stimulation at 1.4 × 10^?9 of exogenous PGE₂. The amount of endogenous PGE₂ synthesized by 1 × 10⁶ fresh, nonstimulated neonatal PML according to gas chromatography-mass spectrometry assay was 5 ng (1.4 × 10^?8 M). The synthesis increased to 27 ng/10⁶ cells after 18 hours' incubation. These concentrations are similar to the ones of exogenous PGE₂ at which neonatal PML were slightly stimulated but the maternal cells were still suppressed. Preincubation for 18 h at 37°C decreased the PGE₂-induced suppression of the adult PML but did not change the response of the neonatal PML.     

Characterization of high-affinity antifluorescyl IgM antibodies

High-affinity IgM rabbit antibodies were elicited using the fluorescein hapten system. Purity and identification of IgM and IgG anti-fluorescyl antibodies was determined by immunoelectrophoresis and SDS-polyacrylamide gel electrophoresis. Ultracentrifugation studies verified that liganded antibodies were of a high mol. wt (901 kd).Comparative analyses of IgM and IgG anti-fluorescyl antibody active sites substantiated the observation that purified IgM preparations, similar to their IgG counterparts, possessed high-affinity antibody active sites. Dissociation rate data confirmed that some IgM molecules within the purified antibody populations possessed association constants at 10¹¹M^?1, comparable with values of 10¹¹M^?1 or greater obtained for some anti-fluorescein IgG populations studied in this laboratory. A diffusion-controlled association rate of 4.6 × 10⁸M^?1 sec^?1 (Levison et al., 1971) was assumed in dissociation rate calculations. This is the first report of purified IgM antibodies possessing exceptionally high affinities.     

The Production of High Affinity Monoclonal Antibodies to Human Chorionic Gonadotropin and Their Application to Immunoradiometric Assay

Abstract

Production of monoclonal antibodies against hCG has been studied using hCG as the antigen. This study reports the successful isolation of hybrid clones secreting monoclonal antibodies specific for hCG with an affinity constant higher than 10¹⁰M^?l. Of 23 fusions, only 17 fusions have produced positive clones which secrete antibodies giving high levels of binding with ^l25I-labelled hCG in the supernatant. Finally, 6 different monoclonal antibodies have been isolated; 4 of them, specific for the β-subunit, with a Ka approximately 1.1–4.0 ± 10¹¹M^?1 and 2 others, specific for the α-subunit, presenting an affinity of 2.5 ± 10¹⁰M^?l. When the antibodies specific for the β-subunit are used, specific and highly sensitive radioim-munoassays are obtained after only 3 hrs of incubation. Using iodinated monoclonal antibodies specific for the α-subunit and tubes coated with antibodies against the β-subunit, we have developped sensitive immunoradiometric assays.     

The binding of soluble immune complexes of guinea pig IgG2 to homologous peritoneal macrophages Determination of the avidity constants at 4 °C.

Soluble immune complexes of guinea pig IgG₂ anti-DNP (2,4-dinitrophenyl) antibodies and DNP₁₉BSA (bovine serum albumin) were prepared at a variety of antibody-to-antigen ratios. The mean sizes of the complexes were determined by gel filtration, and equilibrium binding of the complexes to homologous peritoneal macrophages was measured at 4°C. Scatchard plots of the binding data were linear indicating that the complexes were binding to a uniform population of functionally independent membrane receptors. The avidity constants for complex binding to macrophages increased from 15.4 × 10⁷ M^?1 for complexes containing an average of two antibody molecules to 59.0 × 10⁷ M^?1 for complexes containing an average of four, compared with an association constant for monomeric IgG₂ of 0.21 × 10⁷ M^?1. Calculation of the molar-free energy changes accompanying monomer and immune complex binding revealed not only that the intrinsic binding activity of mononer was sufficient to account for the complex binding activities by simple cooperation of linked antibodies, but also that the cross- linking of antibodies with antigen imposed a strain on the antibody-receptor interaction, resulting in complex binding energies that were lower than the values expected from a simple cooperative mechanism. Complex inhibition by monomeric IgG₂ of unrelated antibody specificity was studied, and it was observed that high concentrations of monomer led to an increase in macrophage discrimination between complexes of different size. The relevance of this finding to the in vivo clearance of circulating complexes is discussed.     

First order dissociation rates between a subpopulation of high affinity rabbit anti-fluorescyl IgG antibody and homologous ligand

The first order dissociation rates of liganded subpopulations of purified hyperimmune rabbit antifluorescyl IgG antibodies were determined using the method of Green (1963). The dissociation of radiolabeled fluorescyl ligands was measured in the presence of excess unlabeled homologous hapten. Results with three different antibody preparations indicated dissociation rates of 1.3 × 10[su?3, 2.4 × 10^?4 and 2.2 × 10^?6 sec^?1 for the liganded subpopulations. Assuming an association rate of 4.6 × 10⁸M^?1 sec^?1 (Levison et al., 1971), average equilibrium constants ranging from 3.1 × 10¹¹M^?1 to 2.1 × 10¹⁴M^?1 were calculated. These values are among the highest reported for antibody-hapten interactions.     

Quantitative explanation for increased affinity shown by mixtures of monoclonal antibodies: Importance of a circular complex

Mixtures of some but not all monoclonal antibodies which bind to separate epitopes on human chorionic gonadotropin (hCG) show an increased affinity for the hormone. To find an explanation for the increase in affinity, we developed a mathematical model which predicts the quantities of intermediates formed when pairs of IgG1 mouse monoclonal antibodies having affinities of ～ 10⁸M^?1 for hCG are mixed with the hormone. At low antibody concentrations (i.e. < 1 nM or 0.15 μg/ml) analysis of possible antibody-hormone combinations, including linear and circular chains composed of less than 12 molecules of antibody and 12 molecules of hCG, suggests the increase in affinity is due to formation of a circular complex containing two molecules of antibody and two of hCG. Further, the model predicts that the circular complex will be the major species formed at antibody-antigen equivalence. This prediction is supported by experimental observations on the molecular weight of a new complex formed in the presence of hCG and the mixture of the monoclonal antibodies. In addition, based on experimental values of binding constants for individual antibodies to hCG, the model correctly quantifies the loss in complex observed in the presence of excess hCG antigen. At high antibody concentrations (i.e. > 10 nM or 1.5 μg/ml) the formation of linear chains of antibody-hCG pairs becomes appreciable and contributes to the increase in apparent affinity of the mixture for hCG. These results suggest that the observed affinity of complex mixtures of antibody for antigens containing multiple epitopes calculated from Scatchard plots may not be related to the affinity or avidity of any of the antibody species for a given epitope.     

The Complement—Fixing Activity of Immune Complexes Containing IgG Antibodies of Different Functional Affinities: Effects on Superoxide Production by Rabbit Neutrophils

When neutrophil phagocytes are stimulated by IgG containing immune complexes (IgG‐IC), with or without the participation of the complement system, they show a sharp increase in oxygen uptake and begin to release large quantities of superoxide anions (O₂^?) and hydrogen peroxide (H₂O₂) into the surrounding medium. The aim of the present investigation was to provide insights into the production and release of O₂^? by rabbit neutrophils activated with immune complexes (IC) containing IgG antibodies of different functional affinity, opsonized and not opsonized by complement system components. For this purpose, two populations of polyclonal anti‐ovalbumin (OVA) IgG antibodies with different functional affinity, 5 × 10⁸ M^{? 1} and 2 × 10⁷ M^{? 1}, were prepared. The production of O₂^? was measured spectrophotometrically by a method using the superoxide dismutase‐inhibited reduction of ferricytochrome C to the ferrous form. The activation of complement by different IgG‐IC was determined by estimating the total residual haemolytic activity of the alternative and classical pathways in sera treated with different concentrations of anti‐OVA IgG/OVA immune complexes formed at equivalence. The results showed that: 1) antibody functional affinity influenced O₂^? production and the complement‐fixing activity induced by the IC. In general, the higher functional affinity antibodies were more efficient in stimulating the respiratory burst of neutrophils and in activating complement by the classical and alternative pathways than the lower functional affinity antibodies at all IC concentrations tested; 2) complement components incorporated into the immune complex lattice caused an increase in the stimulatory activity of both IgG antibodies to produce O₂^? (? 15% for the IC of IgG with K_a = 5 × 10⁸ M^{? 1} and ? 7% for the IC of IgG with K_a = 2 × 10⁷ M^{? 1}). This effect was dependent on antibody affinity and concentration; 3) there was a direct relationship between the overall level of complement activation, antibody affinity and superoxide production by neutrophils. Thus, we conclude that antibody affinity influences immune complex lattice formation, modulating its three‐dimensional structure and the disposition of Fc fragments interfering with the antibody's biological properties. These results can help understand the precise role of antibody functional affinity in antigen‐antibody complex diseases and define the immunochemical characteristics of pathogenic complexes.     

Characterization of a Monoclonal Antibody that Binds to Apolipoprotein E and to Lipoprotein of Human Plasma Containing APO E. Applications to ELISA Quantification of Plasma APO E

Abstract

This study describes the development of an enzyme-linked immunosorbent assay for human apolipoprotein E (apo E).

A mouse monoclonal IgG₁ antibody named E01 against apolipoprotein E was selected from five antibodies secreted by hybridomas. This antibody had a high affinity for apo E ((K a 1.2 × 10⁷ L.M^?1 for purified apo E and K = 1.05 × 10⁷ L.M^?1 for native apo E in very low density lipoproteins) in liquid phase and recognized every isoform of apo E but not other proteins in VLDL. Competition experiments with ¹²⁵I apo E showed that its binding affinity for the E in every density class (VLDL, HDL, LDL) and in serum was the same.

This antibody was used for the quantification of human apo E in serum by enzyme linked immunoassay. E01 was coated on microtiter plates and a polyclonal peroxidase-conjugate was used as second antibody. A good correlation was observed between the values obtained for apo E using both monoclonal and polyclonal antibodies.     

Inhibition of neuraminidase activity by derivatives of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid

Eighteen derivatives of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid were assayed for inhibitory activity against neuraminidases from viral and bacterial sources. Twelve of these compounds were active against neuraminidases of Vibrio cholerae, influenza $\text{A}\text{Mel}\text{,}\text{B}\text{Lee}$, and Newcastle disease virus, causing 50% enzyme inhibition in concentrations ranging from 10^?3M to 10^?6M. The most active of them and the most potent neuraminidase inhibitor described so far is 2-deoxy-2,3-dehydro-N-trifluoroacetylneuraminic acid. This compound has an inhibitor constant (K_i) of 7,9 × 10^?7, M for influenza $\text{A}\text{Mel}$ virus neuraminidase whereas the K_m of the virus enzyme for the substrate is 1000 times weaker (K_m = 6, 9 × 10^?4M). The mechanism of inhibition is competitive, and enzyme inhibition is independent of enzyme concentration. 2-Deoxy-2,3-dehydro-N-trifluoroacetylneuraminic acid inhibits hemagglutination by NDV and SV5 but does not inhibit agglutination of red cells by Sendai virus or influenza A and B viruses.     

Diamine oxydase in rabbit small intestine: Separation from a soluble monoamine oxidase,properties and pathophysiological significance in intestinal ischemia

From all mammals investigated so far only in rabbits diamine oxidase could not be detected in any tissue except the gut. Thus this species was chosen for studying the physiological and pathophysiological function of this enzyme in the gastrointestinal tract. By gel filtration on Sephadex G 50 and G 200 the enzyme was purified 100-fold, separated from a soluble monoamine oxidase, and the properties of the two enzymes were determined. Diamine oxidase from rabbit small intestine deaminated putrescine (K _m =1.3×10^?4 M, pH-optimum 6.4–6.9) and histamine (K _m =8×10^?5 M, pH-optimum 7.5), but not serotonin, and was inhibited by aminoguanidine, but not by pargyline. Soluble monoamine oxidase from rabbit small intestine catabolized serotonin (K _m =1.8×10^?4 M, pH-optimum 8.8), but not putrescine and histamine, and was inhibited by pargyline, but not by aminoguanidine. Based on its properties in vitro intestinal diamine oxidase could inactivate the vasoactive biogenic amine histamine in vivo. To confirm this hypothesis, in rabbits the small intestine was damaged severely by inducing total intestinal ischemia, which occurs as mesenteric infarction also in human subjects and is accompanied by histamine release. Treatment with aminoguanidine and ischemia killed the animals 3-times faster than ischemia alone, which supported our hypothesis on a protective role of intestinal diamine oxidase against histamine.     

Comparison of the effect of PGE2 and somatostatin on histamine stimulated14C-aminopyrine uptake and cyclic AMP formation in isolated rat gastric mucosal cells

In isolated rat gastric cells somatostatin and PGE₂ were compared in respect to their effects on the cAMP system and on the histamine-stimulated H⁺-production, measured by¹⁴C-aminopyrine (¹⁴C-AP) uptake. Like PGE₂ somatostatin activated adenylate cyclase (AC) for all in non-parietal cells. This effect on AC declined in cell fractions with increasing number of parietal cells. Activation of AC or elevation of cellular cAMP and uptake of¹⁴C-AP in response to histamine were inhibited by 10^?9 to 10^?5 mol/l PGE₂ and somatostatin. The results indicate remarkable similarity between somatostatin and PGE₂: both activate a non-parietal cell AC and both inhibit H⁺-production, likely by interfering at the histamine sensitive AC of the parietal cell.     

The NH2-terminal domain of rat CD2 binds rat CD48 with a low affinity and binding does not require glycosylation of CD2

CD2, CD48 and CD58 are structurally similar cell adhesion-molecules forming a subset of the immunoglobulin superfamily (IgSF). In humans CD58 is a ligand for CD2 while in mice CD2 binds CD48. We constructed a soluble chimeric molecule comprising the extracellular portion of rat CD48 and domains 3 and 4 of rat CD4 (sCD48-CD4) and used it to examine whether CD2 is a ligand for CD48 in rats. sCD48-CD4-coated polystyrene Dynabeads? formed rosettes on rat CD2-transfected COS-7 cells, and this rosetting was blocked by anti-CD2 (OX34) and anti-CD48 (OX45) monoclonal antibodies. We used sucrose-gradient ultracentri-fugation to show that sCD48-CD4 binds, in solution, to soluble forms of rat CD2 including the single NH₂-terminal IgSF domain of rat CD2 expressed in bacteria. The upper limit of the affinity of the rat CD48-CD2 interaction is 4 × 10⁵ M^?1, lower than the published affinity of human CD2 for CD58. These results show that rat CD48 binds CD2 on its NH₂-terminal IgSF domain with a low affinity and that binding is independent of glycosylation.     

Affinity of the interaction between Fcgamma receptor type III (FcγRIII) and monomeric human IgG subclasses. Role of FcγRIII glycosylation

Binding of the Fc region of IgG antibodies to low affinity Fcγ receptors (FcγR) triggers important effector functions in the immune system. The type IIIb FcγR (FcγRIIIb or CD16) is a heavily glycosylated protein anchored to the membrane of neutrophils by a glycosylphosphatidylinositol link. This receptor contributes to cell activation by IgG immune complexes. To better understand the nature of the ligand-receptor association, we have studied the affinity and kinetics of the interaction between human IgG subclasses and two soluble forms of FcγRIIIb (sFcγRIIIb or sCD16) corresponding to the 188 N-terminal amino acids of the extracellular region of the receptor, a glycosylated one made in eucaryotic cells (euc.sCD16) and a non-glycosylated one (proc.sCD16) made in Escherichia coli. Experiments using a BIAcore^TM instrument, to measure protein binding in real time, showed that monomeric human IgG1 and IgG3, but not IgG2, IgG4, IgA and divalent antigen-binding fragments (F(ab′)₂) of IgG1, bound to immobilized euc.sCD16 with an affinity constant (K_A) of 1.3 ± 0.6 × 10⁶ M^?1 and 2.6 ± 0.4 × 10⁵ M^?1, respectively. The affinity constant of proc.sCD16 for human IgG1 was in the same range (1.1 ± 0.2 × 10⁶ M^?1), whereas that for human IgG3 was twofold higher (4.2 ± 0.4 × 10⁵ M^?1). The specificity of the non-glycosylated receptor for human IgG subclasses bound to Sepharose was IgG1 > IgG3 ? IgG4 ? IgG2. Thus, the extracellular polypeptide of FcγRIIIb dictates the interaction of the receptor with IgG subclasses although glycosylation plays an inhibitory role in the interaction with human IgG3.     

Exercise volume and intensity: a dose–response relationship with health benefits

Introduction

The health benefits of exercise are well established. However, the relationship between exercise volume and intensity and health benefits remains unclear, particularly the benefits of low-volume and intensity exercise.

Purpose

The primary purpose of this investigation was, therefore, to examine the dose–response relationship between exercise volume and intensity with derived health benefits including volumes and intensity of activity well below international recommendations.

Methods

Generally healthy, active participants (n = 72; age = 44 ± 13 years) were assigned randomly to control (n = 10) or one of five 13-week exercise programs: (1) 10-min brisk walking 1×/week (n = 10), (2) 10-min brisk walking 3×/week (n = 10), (3) 30-min brisk walking 3×/week (n = 18), (4) 60-min brisk walking 3×/week (n = 10), and (5) 30-min running 3×/week (n = 14), in addition to their regular physical activity. Health measures evaluated pre- and post-training including blood pressure, body composition, fasting lipids and glucose, and maximal aerobic power (VO₂max).

Results

Health improvements were observed among programs at least 30 min in duration, including body composition and VO₂max: 30-min walking 28.8–34.5 mL kg^?1 min^?1, 60-min walking 25.1–28.9 mL kg^?1 min^?1, and 30-min running 32.4–36.4 mL kg^?1 min^?1. The greater intensity running program also demonstrated improvements in triglycerides.

Conclusion

In healthy active individuals, a physical activity program of at least 30 min in duration for three sessions/per week is associated with consistent improvements in health status.     

In vitro binding studies of anti-human lymphocyte globulin: analysis of samples tested for immunosuppression in the primate skin allograft system.

We measured the rates and the quantity of antibody which binds to cultured human lymphoblasts, thymus and, in some cases, Hela cells in 28 anti-human and 2 anti-baboon lymphocyte sera and in 9 normal sera submitted to the National Naval Medical Center for immunosuppressive testing in primates. The quantity of ¹²⁵-J-labeled ALG which binds to 1 × 10⁶ lymphoblasts during 60 min incubation at 37°C correlates well (r = 0.648) with the degree of immunosuppression produced by these same ALGs in rhesus monkeys. Twenty-one of the 22 immunosuppressive sera bound ≥6 × 10^?13 moles IgG per 10⁶ lymphoblasts under conditions of the test whereas none of the 9 normal sera and only 3 of the 8 non-immunosuppressive sera bound this amount.Further studies of 2 of the 3 non-immunosuppressive ALGs which contained substantial quantities of lymphoblast binding antibodies revealed that one totally lacked antibodies able to bind to human thymus cells. The other contained thymus-reactive anti-bodies but, in comparison with two ALGs known to be immunosuppressive, it contained much less thymus cell-specific antibody as well as much less antibody cross-reactive with other human cells. All unabsorbed ALGs tested, regardless of immunosuppressive ability, contained more antibodies reactive with Hela cells ot lymphoblasts than with thymus cells. Thus, the chief feature which appears to distinguish highly immunosuppressive anti-human ALGs from those with only modest or no ability to prolong graft survival in rhesus monkeys is their content of relatively large quantities of avid antibodies reactive with human thymus cells.These studies demonstrate the ability of this in vitro test not only to rapidly identify ALGs which are likely to be immunosuppressive, but more importantly, to measure directly the relative avidity, specificity, and quantity of their antibodies reactive with lymphoid and non-lymphoid target cells.