bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal structure of trehalose‐6‐phosphate phosphatase–related protein: Biochemical and biological implications
Authors: Rao Krishnamurthy N. , Kumaran Desigan , Seetharaman Jayaraman , Bonanno Jeffrey B. , Burley Stephen K. , Swaminathan Subramanyam
Published: June 2006

We report here the crystal structure of a trehalose‐6‐phosphate phosphatase–related protein (T6PP) from Thermoplasma acidophilum, TA1209, determined by the dual‐wavelength anomalous diffraction (DAD) method. T6PP is a member of the haloacid dehalogenase (HAD) superfamily with significant sequence homology with trehalose‐6‐phosphate phosphatase, phosphoserine phosphatase, P‐type ATPases and other members of the family. T6PP possesses a core domain of known α/β‐hydrolase fold, characteristic of the HAD family, and a cap domain, with a tertiary fold consisting of a four‐stranded β‐sheet with two α‐helices on one side of the sheet. An active‐site magnesium ion and a glycerol molecule bound at the interface between the two domains provide insight into the mode of substrate binding by T6PP. A trehalose‐6‐phosphate molecule modeled into a cage formed by the two domains makes favorable interactions with the protein molecule. We have confirmed that T6PP is a trehalose phosphatase from amino acid sequence, three‐dimensional structure, and biochemical assays.
Lessons in stability from thermophilic proteins
Authors: Razvi Abbas , Scholtz J. Martin
Published: June 2006

Studies that compare proteins from thermophilic and mesophilic organisms can provide insights into ability of thermophiles to function at their high habitat temperatures and may provide clues that enable us to better define the forces that stabilize all proteins. Most of the comparative studies have focused on thermal stability and show, as expected, that thermophilic proteins have higher Tm values than their mesophilic counterparts. Although these comparisons are useful, more detailed thermodynamic analyses are required to reach a more complete understanding of the mechanisms thermophilic protein employ to remain folded over a wider range of temperatures. This complete thermodynamic description allows one to generate a stability curve for a protein that defines how the conformational stability (ΔG) varies with temperature. Here we compare stability curves for many pairs of homologous proteins from thermophilic and mesophilc organisms. Of the basic methods that can be employed to achieve enhanced thermostability, we find that most thermophilic proteins use the simple method that raises the ΔG at all temperatures as the principal way to increase their Tm. We discuss and compare this thermodynamic method with the possible alternatives. In addition we propose ways that structural alterations and changes to the amino acid sequences might give rise to varied methods used to obtain thermostability.
Cooperativity and the origins of rapid, single‐exponential kinetics in protein folding
Authors: Faísca Patrícia F.N. , Plaxco Kevin W.
Published: June 2006

The folding of naturally occurring, single‐domain proteins is usually well described as a simple, single‐exponential process lacking significant trapped states. Here we further explore the hypothesis that the smooth energy landscape this implies, and the rapid kinetics it engenders, arises due to the extraordinary thermodynamic cooperativity of protein folding. Studying Miyazawa‐Jernigan lattice polymers, we find that, even under conditions where the folding energy landscape is relatively optimized (designed sequences folding at their temperature of maximum folding rate), the folding of protein‐like heteropolymers is accelerated when their thermodynamic cooperativity is enhanced by enhancing the nonadditivity of their energy potentials. At lower temperatures, where kinetic traps presumably play a more significant role in defining folding rates, we observe still greater cooperativity‐induced acceleration. Consistent with these observations, we find that the folding kinetics of our computational models more closely approximates single‐exponential behavior as their cooperativity approaches optimal levels. These observations suggest that the rapid folding of naturally occurring proteins is, in part, a consequence of their remarkably cooperative folding.
Bacteriorhodopsin chimeras containing the third cytoplasmic loop of bovine rhodopsin activate transducin for GTP/GDP exchange
Authors: Geiser Andrew H. , Sievert Michael K. , Guo Lian‐Wang , Grant Jennifer E. , Krebs Mark P. , Fotiadis Dimitrios , Engel Andreas , Ruoho Arnold E.
Published: June 2006

The mechanisms by which G‐protein‐coupled receptors (GPCRs) activate G‐proteins are not well understood due to the lack of atomic structures of GPCRs in an active form or in GPCR/G‐protein complexes. For study of GPCR/G‐protein interactions, we have generated a series of chimeras by replacing the third cytoplasmic loop of a scaffold protein bacteriorhodopsin (bR) with various lengths of cytoplasmic loop 3 of bovine rhodopsin (Rh), and one such chimera containing loop 3 of the human β2‐adrenergic receptor. The chimeras expressed in the archaeon Halobacterium salinarum formed purple membrane lattices thus facilitating robust protein purification. Retinal was correctly incorporated into the chimeras, as determined by spectrophotometry. A 2D crystal (lattice) was evidenced by circular dichroism analysis, and proper organization of homotrimers formed by the bR/Rh loop 3 chimera Rh3C was clearly illustrated by atomic force microscopy. Most interestingly, Rh3C (and Rh3G to a lesser extent) was functional in activation of GTPγ35S/GDP exchange of the transducin α subunit (Gαt) at a level 3.5‐fold higher than the basal exchange. This activation was inhibited by GDP and by a high‐affinity peptide analog of the Gαt C terminus, indicating specificity in the exchange reaction. Furthermore, a specific physical interaction between the chimera Rh3C loop 3 and the Gαt C terminus was demonstrated by cocentrifugation of transducin with Rh3C. This Gαt‐activating bR/Rh chimera is highly likely to be a useful tool for studying GPCR/G‐protein interactions.
Discrepancy between impedance and immunofluorescence platelet counting has implications for clinical decision making in patients with idiopathic thrombocytopenia purpura
Authors: Bowles Kristian M. , Bloxham David M. , Perry David J. , Baglin Trevor P.
Published: June 2006

This study investigated whether differences occur between the impedance and immunofluorescence methods for platelet quantification in idiopathic thrombocytopenia purpura (ITP). Immunofluorescence gave a platelet count >50% higher than the impedance test in 9/35 (26%) patients, of which 4/35 (11%) were >100% higher. The clinical severity of thrombocytopenia was changed as a result of the immunofluorescence test in 14/35 (40%) patients. Neither mean platelet volume nor platelet distribution width predicted impedance/immunofluorescence method discrepancy. It is suggested that immunofluorescence platelet counts should be performed on all ITP patients when the implementation of a therapeutic or diagnostic intervention is being considered.
Minimal residual disease directed therapy for childhood acute myeloid leukaemia: the time is now
Authors: Goulden Nick , Virgo Paul , Grimwade David
Published: June 2006

The continued improvement in the prognosis of childhood acute myeloid leukaemia (AML) has been paralleled by the use of increasingly intensive therapy. This has led to attempts to develop risk‐directed strategies in which the most intensive treatment is reserved for those at highest risk of relapse. Unfortunately, current approaches, which rely on cytogenetic sub‐grouping and morphological assessment of response to therapy, are inaccurate. New prognostic factors are needed. This annotation proposes that the introduction of protocols based on the measurement of minimal residual disease (MRD) holds the key to progression from an era of ‘cure at all costs’ to a more individualised approach. However, the full potential of MRD technologies will only be realised through properly designed studies with scrupulous attention to logistics and quality assurance. The article illustrates which children may benefit most from MRD analysis in AML and explores practical issues that should be addressed in the design of clinical trials.
Natural killer T cells and haemopoiesis
Authors: Karadimitris Anastasios , Patterson Scott , Spanoudakis Emmanouil
Published: June 2006

Invariant natural killer T (iNKT) cells are a small but powerful subset of regulatory T cells involved in the modulation of a variety of normal and pathological immune responses. In contrast to conventional or other types of regulatory T cells, they are activated by glycolipid and phospholipid ligands that are presented to them by the non‐polymorphic, major histocompatibility complex class I‐like molecule CD1d. The in‐depth understanding of their function has resulted in successful, iNKT cell‐centred experimental therapeutic interventions including prevention of graft‐versus‐host disease and anti‐leukaemia effects. Extending these successes into the clinical arena will require better understanding of their contribution to the pathogenesis of human, including haematological, diseases.
Diagnosis of Burkitt lymphoma in due time: a practical approach
Authors: Cogliatti Sergio B. , Novak Urban , Henz Samuel , Schmid Ulrico , Möller Peter , Barth Thomas F. E.
Published: June 2006

The quick diagnosis of Burkitt lymphoma (BL) and its clear‐cut differentiation from diffuse large B‐cell lymphoma (DLBCL) is of great clinical importance because treatment strategies for these two disease entities differ markedly. As these two lymphomas are difficult to distinguish using the current World Health Organization classification, we studied 39 cases of highly proliferative peripheral blastic B‐cell lymphoma (HPBCL) to establish a practical differential‐diagnostic algorithm. Characteristics set for BL were a typical morphology, a mature B‐cell phenotype of CD10+, Bcl‐6+ and Bcl‐2− tumour cells, a proliferation rate of >95%, and the presence of C‐MYC rearrangements in the absence of t(14;18)(q32;q21). Altogether, these characteristics were found in only five of 39 cases, whereas the majority of tumours revealed mosaic features. We then followed a pragmatic stepwise approach for a classification algorithm that included the assessment of C‐MYC status to stratify HPBCL into four predefined diagnostic categories (DC), namely DC I (5/39, 12.8%): ‘classical BL’, DC II (11/39, 28.2%): ‘atypical BL’, DC III (9/39, 23.1%): ‘C‐MYC+ DLBCL’ and DC IV (14/39, 35.9%): ‘C‐MYC− HPBCL’. This proposal may serve as a robust and objective operational basis for therapeutic decisions for HPBCL within 1 week and is applicable to be evaluated for its prognostic relevance in clinical trials with uniformly treated patients.
Statistical aspects of efficacy evaluation of plant protection products in field trials – a comment on EPPO Standard PP1/152
Authors: Hothorn L. A. , Bleiholder H.
Published: July 2006

The evaluation of plant protection product efficacy in field trials is a complex task. Several aspects of the statistical evaluation are discussed in this paper, along with a recommendation to modify EPPO Standard PP1/152. Confidence intervals should be preferred over significance tests to avoid contradictions between ‘statistical significance’ and ‘biological relevance’. Efficacy should first be demonstrated, by comparison of a new product with a well chosen reference product, using a test of non‐inferiority. When non‐inferiority has been established, a test of superiority can follow. Both can simply be obtained by one‐sided confidence intervals of µReference–µProductor µReference/µProduct, where µReferenceand µProductare the means for the reference and the product, respectively. Confidence intervals for the ratio are easier to interpret because of the definition of percentage change. The evaluation that a trial is realistic and coherent should be performed according to the present EPPO guideline before any analysis of efficacy is made. Efficacy data from trial series should be preferred over individual trials because this represents different sites and increased sample size (number of sites and number of plots). The treatments‐by‐sites interaction should be modelled as a random effect in a mixed model. Software in R is available for these suggested analyses.
Phytosanitary risk of bruchids in lentil imported into India
Authors: Bhalla S. , Gupta K. , Kapur M. L. , Lal B. , Khetarpal R. K.
Published: July 2006

Import of lentil grain for various purposes involves an inherent risk of introducing exotic pests. There are 26 seed pests reported on lentil including 18 bruchids, of which 12 have not yet been reported from India. These may be transported across geographical boundaries as hidden infestations of imported lentil grain. An attempt has been made to analyse the literature, according to the relevant ISPMs, to provide scientific justification of the relevant phytosanitary measures applied in India. The various aspects of risk analysis considered were: initiation (compilation of world pest record and identification of pathway), risk assessment (ascertaining pest status, pest distribution, damage, host range, etc.) and risk management (pest exclusion) through X‐ray radiography, thermal and insecticidal treatments. The repeated detection of bruchids in imported breeding material of lentil (Acanthoscelides obtectus, Bruchus ervi, Bruchus lentis, Callosobruchus analis, Callosobruchus chinensis and Callosobruchus maculates) highlights their potential phytosanitary importance in bulk imports. Analysis of risk prior to import is the first step in this direction.
Surveillance and monitoring for plant parasitic nematodes – a challenge
Authors:   Rajan
Published: July 2006

Surveillance of pests is an important activity for (a) early detection and prevention of spread of indigenous and exotic pests, (b) delimiting pest distribution, (c) searching for pest free areas for meeting the requirements of national and international trade and (d) to achieve effective management of pests that affect crop production. Recent developments on these topics are reviewed with special reference to plant parasitic nematodes in India.
Seed‐borne fungi detected in consignments of soybean seeds (Glycine max) imported into India
Authors: Agarwal P. C. , Dev U. , Singh B. , Indra R. , Khetarpal R. K.
Published: July 2006

Inspection of 16 017 samples of soybean seeds imported into India from 1978 to 2004 resulted in the detection of 21 pathogens, including Peronospora manshurica which is not present in India. Seed‐borne fungi of high economic significance included: Ascochyta sojicola, Botryotinia fuckeliana, Cercospora kikuchii, Colletotrichum dematium, Corynespora cassicola, Diaporthe phaseolorum var. sojae, Fusarium oxysporum, Glomerella cingulata, Glomerella glycines, Macrophomina phaseolina, Nectria haematococca, Passalora sojina, Thanatephorus cucumeris as well as other fungal pathogens for which soybean is not a host such as Alternaria padwickii, Cochliobolus sativus, Fusarium culmorum, Fusarium poae, Glomerella graminicola, Setosphaeria rostrata, Verticillium albo‐atrum, etc. Some of the fungi detected have very wide host range. Details are presented on the fungi detected, the countries from which the imported consignments originated, and phytosanitary significance.
Fast‐decaying IP in frozen unconsolidated rocks and potentialities for its use in permafrost‐related TEM studies
Authors: Kozhevnikov N.O. , Antonov E.Y.
Published: June 2006

We investigate the early time induced polarization (IP) phenomenon in frozen unconsolidated rocks and its association with transient electromagnetic (TEM) signals measured in northern regions. The distinguishing feature of these signals is the distortion of the monotony or sign reversals in the time range from a few tens to a few hundreds of microseconds. In simulating TEM data, the IP effects in frozen ground were attributed to the dielectric relaxation phenomenon rather than to the frequency‐dependent conductivity. This enabled us to use laboratory experimental data available in the literature on dielectric spectroscopy of frozen rocks. In our studies we focused on simulating the transient response of a coincident‐loop configuration in three simple models: (i) a homogeneous frozen earth (half‐space); (ii) a two‐layered earth with the upper layer frozen; (iii) a two‐layered earth with the upper layer unfrozen. The conductivities of both frozen and unfrozen ground were assumed to exhibit no frequency dispersion, whereas the dielectric permittivity of frozen ground was assumed to be described by the Debye model. To simplify the presentation and the comparison analysis of the synthetic data, the TEM response of a frozen polarizable earth was normalized to that of a non‐polarizable earth having the same structure and resistivities as the polarizable earth. The effect of the dielectric relaxation on a TEM signal is marked by a clearly defined minimum. Its time coordinate tmin is approximately three times larger than the dielectric relaxation time constant τ. This suggests the use of tmin for direct estimation of τ, which, in turn, is closely associated with the temperature of frozen unconsolidated rock. The ordinate of the minimum is directly proportional to the static dielectric permittivity of frozen earth. Increasing the resistivity of a frozen earth and/or decreasing the loop size results in a progressively stronger effect of the dielectric relaxation on the TEM signal. In the case of unfrozen earth, seasonal freezing is not likely to have an appreciable effect on the TEM signal. However, for the frozen earth, seasonal thawing of a near‐surface layer may result in a noticeable attenuation of the TEM signal features associated with dielectric relaxation in a frozen half‐space. Forward calculations show that the dielectric relaxation of frozen unconsolidated rocks may significantly affect the transient response of a horizontal loop laid on the ground. This conclusion is in agreement with a practical example of inversion of the TEM data measured over the permafrost.
Vector attenuation: elliptical polarization, raypaths and the Rayleigh‐window effect
Authors: Carcione José M.
Published: June 2006

Waves in dissipative media exhibit elliptical polarization. The direction of the major axis of the ellipse deviates from the propagation direction. In addition, Snell's law does not give the raypath, since the propagation (wavevector) direction does not coincide with the energy‐flux direction. Each of these physical characteristics depends on the properties of the medium and on the inhomogeneity angle of the wave. The calculations are relevant for multicomponent surveys, where the receivers are placed on the ocean‐floor. An example of the role played by inhomogeneous waves is given by the Rayleigh‐window effect, which implies a significant amplitude reduction of the reflection coefficient of the ocean‐bottom.
A Low‐Dose Immunization Schedule for the Production of ALG in Rabbits.
Authors: AXELSEN N. H. , CLAESSON M. H. , HARDT F. , RANLØV P. , RöPKE C.
Published: June 2006

ALG was produced in rabbits by intracutaneous injections of small doses (106 cells) of C3H mouse thymocytes suspended in Freund's incomplete adjuvant. The immunosuppressive potency of this ‘low‐dose’ ALG evaluated by allo‐skin graft survival proved to be comparable to that of ALG produced by intravenous injection of high doses of lymphoid cells (ad modum Levey & Medawar). In addition the ‘low‐dose’ method gave rise to negligible amounts of haemagglutinins, lymphagglutinins, and lymphocytotoxic antibodies. The ‘low‐dose’ method may represent a major advantage in overcoming the limiting factor presented by scarcity of available antigen, which is regularly the case in human ALG production.
Studies on the Induction of Antibody Synthesis against Sulfanilic Acid in Rabbits.
Authors: RUBIN B.
Published: June 2006

The present experiments (carried out in rabbits) have demonstrated that antibodies directed against new antigenic determinants introduced in rabbit serum albumin (RSA) through the coupling with sulfanilic acid (Sulf) were able to enhance (or‘help’) a primary antibody response to Sulf11RSA. This enhancement phenomenon was shown to be specific for Sulf‐carrier conjugates.
Delayed‐Type Hypersensitivity in the Mouse
Authors: COOPER M. G.
Published: June 2006

A simple reproducible footpad assay of delayed‐type hypersensitivity (DTH) in CBA, C3H, and Bagg mice to Salmonella adelaide flagellin and its derivatives is described. DTH reactions were of delayed onset (12‐24 hours), long duration (3‐4 days), and characterized histologically by extensive infiltration of the hypodermis and muscle with mononuclear cells. Immediate (0‐3 hours) and late (36‐48 hours) Arthus reactions were also observed in certain instances but did not preclude detection of the 24‐hour DTH reaction. Maximal DTH reactivity was induced by microgram doses of monomeric (MON) or polymerized (POL) flagellin in saline, 2‐8 days after primary challenge. POL elicited greater DTH reactions than MON, presumably because of its larger size.
Studies of Antibody Formation in Vitro and in Lethally Irradiated Reconstituted Mice
Authors: EIDINGER D. , PROSS H.
Published: June 2006

The reconstitutive capacity of normal lymphoid cells versus cells obtained from mice immunized with keyhole limpet haemocyanin was studied in lethally irradiated syngeneic recipients using horse erythrocytes as the test antigen. Evidence was obtained for an immune deficiency in the inoculum from immune donors, which was interpreted as evidence in favour of a cellular mechanism to account for antigen‐induced suppression (‘antigenic competition’). The unexpected inhibition of reconstitution with excessive numbers of normal spleen cells was duplicated in experiments using thymus or thymus‐derived cells. Experiments assessing the effect of cortisone‐resistant thymus cells on the response of normal spleen cells, in vivo and in vitro, gave evidence that a relative surplus of such thymus cells possess a capability for suppressing antibody formation. Since helper function by T cells is now well documented, this work is further indicative of the broader view, namely immuno‐regulation by T cells.
Evidence that the Mechanism of Immunological Tolerance (‘Central Failure’) Is Operative in the Lack of Host Resistance in Lepromatous Leprosy
Authors: GODAL T. , MYRVANG B. , FROLAND S. S. , SHAO J. , MELAKU G.
Published: June 2006

The cellular immune defect in lepromatous leprosy has been studied. The following observations have been made: 1) Three lepromatous patients who had been on anti‐leprosy treatment for more than 10 years still failed to respond to M. leprae by lymphocyte transformation (mean 0.2%) while they responded strongly to BCG (mean 34.2%) and PPD (mean 56.1%). 2) Lepromatous serum failed to inhibit M. leprae‐induced lymphocyte transformation and M. leprae‐induced leukocyte migration inhibition. 3) Lepromatous lymphocytes revealed a reduced capacity to attach M. leprae to their surface. The only experimental condition compatible with the observed characteristics would seem to be a state of immunological tolerance to an antigen (or antigens) of M. leprae. The lasting nature of this non‐responsive state suggests that it plays a primary role in the pathogenesis of lepromatous leprosy.
Evidence for a Receptor Recognizing Antigen Complexed Immunoglobulin on the Surface of Activated Mouse Thymus Lymphocytes
Authors: YOSHIDA T. O. , ANDERSSON B.
Published: June 2006

The distribution in the mouse of lymphoid cells carrying receptors for IgG or IgG‐Ag was investigated. B lymphocytes were found to have receptors reacting with both IgG and IgG‐Ag. Resting T lymphocytes did not react with IgG‐Ag. T lymphocytes activated by passage through irradiated, allogeneic mice had a receptor reacting with IgG‐Ag, but not with IgG.
Membrane‐bound Immunoglobulin (Ig) and In Vitro Production of Ig by Lymphoid Cells from Patients with Primary Immunodeficiencies.
Authors: AIUTI FERNANDO , FONTANA LUIGI , GATTI RICHARD A.
Published: June 2006

The presence and function of B‐lymphocytes were evaluated in ten patients with primary immunodeficiency diseases by studies of the lg‐binding characteristics of lymphocytes and assessment of in vitro synthesis of Ig by lymphoid cells from these patients. One patient with Bruton‐type agammaglobulinemia failed to show any evidence of B‐lymphocytes in peripheral blood and another showed only 3% of IgG‐bearing lymphocytes. No Ig production Could be detected in culture fluids of their lymphoid tissues. Three patients with selective IgA deficiency had normal numbers of IgA‐binding lymphocytes in their peripheral blood; however, IgA could not be detected in tissue culture fluids. In four patients with acquired (common variable) hypogammaglobulinemia, results were variable. This variability strengthens arguments for further subdividing this group of patients and perhaps suggests a means for their regrouping according to the percentage of B‐lymphocytes in the peripheral blood.
Immunological Characterization of Lymphocytes in Synovial Fluid from Patients with Rheumatoid Arthritis
Authors: FRφLAND S. S. , NATVIG J. B. , HUSBY G.
Published: June 2006

Lymphocytes separated from synovial fluid in rheumatoid arthritis by means of gradient centrifugation were characterized with regard to B‐ and T‐lymphocyte properties. Membrane‐bound Ig detectable with immunofluorescence technique was utilized as a marker of B‐lymphocytes, while the ability to bind sheep erythrocytes and form rosettes was interpreted as a T‐lymphocyte characteristic. In 9 out of 18 patients studied no Ig‐positive lymphocytes were found in synovial fluid, while the remaining 9 patients had 1% or less. Appropriate control experiments indicated that the absence of membrane‐bound Ig on lymphocytes was not due to in vivo induced redistribution with subsequent endocytosis of Ig receptors. The percentages of B‐lymphocytes in peripheral blood from patients (mean 11% and range 3–19%) were not significantly different from those of 54 normal individuals (mean 10% and range 3–22%). Rosette‐forming lymphocytes were found in synovial fluid of 11 patients studied, with mean 29.6% and range 19.0–60.2%, which are significantly higher than the corresponding values in peripheral blood, 22.7% and 0.9–41.1%. The latter values were also significantly higher than those of peripheral blood from 32 normals (mean 14.8% and range 0.9–34.7%). The increased proportions of T‐lymphocytes in synovial fluid in rheumatoid arthritis in contrast to the absence or very low numbers of B‐lymphocytes may indicate an important role for the former in the pathogenesis of rheumatoid inflammation.
The Effect of Capping by Anti‐immunoglobulin Antibody on the Expression of Cell Surface Immunoglobulin and on Lymphocyte Activation
Authors: ELSON C. J. , SINGH J. , TAYLOR R. B.
Published: June 2006

The ability of mouse spleen cells to bind anti‐mouse immunoglobulin antibody labelled with 125I (anti‐mouse Ig Ab 125I) in vitro was measured. The validity of this technique for quantifying the amount of surface immunoglobulin on mouse spleen cells was established by showing that the specific uptake of anti‐mouse Ig Ab 125I was linearly related to the number of spleen cells present. The technique was used to assess the exposed immunoglobulin determinants on mouse spleen cells after the redistribution of their surface associated immunoglobulins to a polar cap (capping) had been induced by anti‐mouse Ig Ab. It was found that after capping the amount of surface immunoglobulin recovered almost to control levels, but showed no further increase. Treatment of spleen cells with chymotrypsin and papain but not trypsin markedly reduced the quantity of surface immunoglobulin. The rate of immunoglobulin resynthesis after chymotrypsinisation was not affected by previously capping the surface immunoglobulins. Concentrations of anti‐mouse Ig Ab which induced capping of the surface immunoglobulin of spleen cells did not stimulate them to lake up (3H) thymidine although under the same culture conditions spleen cells were activated by phytohaemagglutinin and lipopolysaccharide. It is considered that capping is not in itself a sufficient stimulus to bring about in spleen cells either an increase in the density of the surface immunoglobulin or the initiation of DNA synthesis.
IgM Serum Agglutinators
Authors: WALLER MARION
Published: June 2006

In human sera showing elevated levels of IgM, the serum agglutinators may be of both IgG and IgM classes. When the quantity of IgG is very low, these antibodies may be solely of the IgM class. Elevations in IgM levels subsequent to loss of IgG through the kidney, as in nephrosis, and elevations in all immunoglobulin levels, as observed in severe suppurative infection, do not alter the production of serum agglutinaton as IgG globulins
Stimulation of Organ Specific and Non‐organ Specific Antigens on the Surface of Thyroid Cells by Phytohaemagglutinin P
Authors: JONSSON J. , FAGRAEUS ASTRID , SUNDQVIST K. G
Published: June 2006

Human thyroid primary, secondary and tertiary monolayer cultures with a low concentration of organ and non‐organ specific antigens on the surface of their cells were incubated with different does of phytohaemagglutinin P (PHA). PHA concentrations of 100–500 μg/ml of culture fluid were found to stimulate the appearance of organ‐specific and some not specified non‐organ‐specific antigens that were not demonstrable in unstimulated cultures. The effect was demonstrated with the mixed haemadsorption radial diffusion disc test (MHT) with the mixed haemadsorption isotope test, and with indirect immunofluorescence tests on monolayer cultures grown on cover slips and on suspensions of cells dispersed from monolayer cultures. Whether the stimulatory effect is due to a stimulation of some restricted cell functions or merely to a general stimulation of the cell metabolism that is known to occur, remains to be investigated.
Further Studies on the Mixed Leukocyte Reaction in Multiple Sclerosis and Various Arthritides
Authors: HEDBERG H. , KÄLLEN B , LÖW B , NILSSON O.
Published: June 2006

The mixed leukocyte reaction (MLR) is impaired in multiple sclerosis and certain arthritides, notably rheumatoid arthritis. The present study shows that this phenomenon is not disease‐Specific: cells from patients with multiple sclerosis react poorly also with cells from patients with arthritis. A time study of the reaction excludes the possibility of an initial Strong MLR followed by cell death – a phenomenon sometimes seen in animal experiments. A study of the affect ot patient sera on a two‐way MLR between normal individuals shows that a small depressive effect is present with the patient sera, but this is not of the magnitude that it can explain the MLR impairment under study.
Conjugates of Immunoglobulin G with Different Fluorochromes
Authors: BRANDTZAEG F.
Published: June 2006

Conjugate fractions of IgG labelled with FITC, MRITC, RB200SC or RBITC were tested on different substrates and the resulting fluorescence was evaluated with the Ploem optical system. Immunofluorescence sensitivity was characterized by the end point of specific staining. Conjugate quality was further defined by a specificity interval factor. Non‐specific staining end points exhibited an inverse semi‐logarithmic correlation with the molar FITC/protein ratio, while the influence of this ratio on specific staining varied greatly between different conjugates. Best sensitivity, combined with a favourable specificity interval, was obtained for selected fractions of MRITC and RB200SC conjugates. An inconsistent tendency of such conjugate fractions to produce non‐specific background staining was reduced by bovine serum albumin or by tissue powder adsorption. Several substrates were evaluated with regard to their usefulness in performance testing Carried out to determine the immunological specificity of conjugates. Reliable evidence of binding specificity was obtained by applying the conjugate absorbed in excess with the corresponding soluble antigen.
Tolerance to Allogeneic Cells Induced in Bursectomized Chickens
Authors: CRONE M.
Published: June 2006

The question of whether the presence of antibody is necessary for tolerance induction was investigated in hormonally bursectomized chickens in which no antibody production could be demonstrated. Tolerance to allogeneic cells was induced by i.v. injection of whole blood from one donor into newly hatched, bursectomized chickens and normal chickens. The state of tolerance obtained in the T‐cell population was judged by GVH reactions and by whattle grafts from the blood donor. Prolonged graft survival was found in both bursectomized and conventional, tolerant chickens and compared with normal controls. The diminished GVH reactivity of blood lymphocytes from tolerized animals was specific for embryos of the tolerogenic B‐genotype and was equally marked with cells from bursectomized and non‐bursectomized birds. No antibodies against the tolerogenic cells could be demonstrated either by haemagglutination or by the ability of serum from tolerant animals to inhibit GVH reactivity of lymphocytes of the tolerogenic type. It is concluded that although the mechanisms involved for the induction of T‐cell tolerance is unknown, there is no evidence from bursectomized chickens that humoral antibodies facilitate the process, or that they are even a necessary requirement.
Immunoglobulins and Other Serum Proteins in Feces from Infants and Children
Authors: HANEBERG B. , TØNDER O.
Published: June 2006

IgA in variable amounts was found in extracts of feces from all of 14 infants and children with no apparent diseases involving the gastrointestinal tract or the immune system, whereas IgG and IgM were only found in some. No age variation was evident's even one‐month‐old infants seemed fully able to secrete intestinal immunoglobulins. Freeze‐drying of the feces facilitated the extraction, and the amounts of immunoglobulins were related to the dry weight of fecas. Most of the immunoglobulins were easily dissolved in saline. Of other serum proteins α1 antitrypsin was constantly present; α1 antichymotrypsin and α2 macroglobulin were found in many. Only traces of albumin were sometimes demonstrated.
Mixed Leukocyte Reaction in Rabbits with Experimental Autoimmune Encephalomyelitis
Authors: LINDH J.
Published: June 2006

Peripheral blood leukocytes from rabbits were used in one‐way mixed leukocyte reaction (MLR), When the rabbits were injected with basic encephalitogenic protein in Freund's complete adjuvant (FCA), an impairment of the MLR occurred, partly resembling that previously described in certain human diseases. This impairment was found to be due to an effect on both the stimulating and the responding phase of the MLR. Similar, but much weaker effects were seen when cells from rabbits injected with saline in FCA were studied. Sera from rabbits with experimental autoimmune encephalomyelitis reduced the two‐way MLR between two normal rabbits, but no clear‐cut effect was seen with sera from rabbits injected with saline in FCA.
Disulfide Bonds of Human IgM: Differential Sensitivity to Reductive Cleavage
Authors: KOWNATZKI E.
Published: June 2006

Two Waldenström Microglobulins were reduced with increasing amounts of dithiothreitol ranging from 0.25 to 2.0 mM. Disruption of intersubunit, interchain and μ‐J chain disulfide bonds was measured by determining the amount of IgMs, μ chains and J chains released at a given DTT concentration. Intersubunit bonds were most labile, while S‐S bonds linking μ and J chains were most resistant to reductive cleavage.
Received 14 May 1973; Relationship between Killer and Rosette‐Forming Cells Reactive to H‐2 478
Authors: BRONDZ B. D. , KOTOMINA I. F. , JELISEYEVA L. S. , EGOROVA S. G. , SNEGIRÖVA A. E.
Published: June 2006

Optimum conditions were selected for testing of direct and indirect H‐2 reactive rosette‐forming cells (RFC) with the use of sheep or mouse erythrocytes coated with soluble H‐2 antigens. Rosette formation with mouse erythrocytes is shown to be an immunologically specific reaction and to be inhibited by the pretreatment of cells with the corresponding soluble H‐2 antigen preparation. Rate of killer cell and RFC formation is different after primary and secondary immunization with an allogeneic tumor, Unlike killer cells. RFCs are inactivated without complement by rabbit antibodies against mouse γ‐globulin (MGG). In contrast to killer cells, which are eliminated in the presence of complement by anti‐θ antibodies but not by anti‐plasma cell antigen (PC.1) and anti‐MGG antibodies, direct RFCs are not inactivated by anti‐θ but are eliminated partiallv by anti‐MGG and anti‐PC1. The RFCs are shown to be concentrated in the low‐density fractions of the discontinuous bovine serum albumin gradient, whereas cytotoxic lymphocytes are distributed less closely, being concentrated in the intermediate fraction, which does not differ morphologically from the initial cell suspension. Killer and rosette‐forming cells reactive to the same H‐2 antigens appear to be two non‐overlapping populations of T and B cells, respectively, and no T‐B cooperation is required for destruction of target cells.
Evidence of 15 S–S Bridges in the Hinge Region of Human 530
Authors: MICHAELSEN T. E.
Published: June 2006

By amino acid analyses and radioactive titration of cleaved S–S bonds on reduction, it was shown that the hinge region of IgG3 and its F(ab′)2 fragment seem to contain 15 S–S bridges. About three of the bridges are not reduced by 0.01 M dithiothreitol in aqueous buffer, and, in addition, this treatment cleaved the F(ab′)2 fragment into two Fab′ subunits. The observation, therefore, may support the idea that the γ3‐chain contains an extra intrachain disulphide loop.
Lymphocyte‐Associated Complement: Role of C8 in Certain Cell‐mediated Lytic Reactions
Authors: PERLMANN P , PERLMANN H. , LACHMANN P.
Published: June 2006

51Cr‐ labelled chicken erythrocytes (E) were treated with human and C7 to form , susceptible to lysis by the terminal complement components C8 and C9 ('reactive lysis') Addition of purified and extensively washed human blood lymphocytes, but not of erythrocytes, to resulted in a similar but cell‐mediated reactive lysis. Contamination of the effector cell preparations with plasma was excluded. The reaction does not require living effector cells. Its dependency on C8 was proved by inhibition with rabbit anti‐human C8 as well as with its F(ab')2 fragments. Although terminal complement components may be of importance for cell‐mediated lysis of complement‐carrying target cell, no effector role could be assigned to them in antibody‐dependent lymphocyte mediated lysis Thus, lysis of antibody‐coated chicken erythrocytes in the absence of added complement by purified human lymphocytes was not inhibited by the F(ab')2 fragment of anti‐C8.
Immunochemical Study of the Interaction between Staphylococcal Protein A, Rabbit Antistaphylococcal Sera, and Selecred Sera from Nonimmunized Animals
Authors: LIND I. , MANSA B.
Published: June 2006

This study is a further investigation of the interaction between staphylococcal protein A and mammalian IgG, particularly as regards the three‐component immunoprecipitation that was described by Kronvall and Williams in 1971 and designated the ‘star phenomenon’. For IgG or the F(ab')2 fragment of IgG, the ability to precipitate protein A did not correlate with the occurrence of staphylococcal antibodies, as demonstrated in an indirect hemagglutination test. or with antibodies that inhibit α‐hemolysin. The star phenomenon required the following three components: protein A; IgG forming soluble complexes with protein A; and F(ab')2 fragments obtained either from rabbit antisera to protein A, from normal IgG that precipitated protein A, or from human myeloma IgG that precipitated protein A. These different (F(ab')2 fragments could co‐operate in the formation of a star only if both protein A and an intact IgG were present. It is suggested that star‐forming F(ab')2 fragments possess combining sites directed against hidden determinants on the IgG molecule, which are made accessible when protein A binds to the Fc piece.
Interferon Production by Lymphocytes in Human Milk
Authors: EMÖDI G. , JUST M.
Published: June 2006

Despite their limited ability to synthesize immunoglobulins (only IgA and not IgM or IgG) lymphocytes of human colostrum and human breast milk can be stimulated by Newcastle disease virus to produce interferon in the same amount as do blood lymphocytes. The maximum interferon production by milk lymphocytes was found on the 4th and the 5th day postpartum.
Antibody‐Induced Hemolytic Activity of Human Blood Monocytes
Authors: HOLM G. , ENGWALL E. , HAMMARSTRÖM S. , NATVIG J. B.
Published: June 2006

The hemolytic effect of purified human blood monocytes was quantitated as the release of isotope from human erythrocytes labeled with 51Cr‐chromate. We here demonstrate that IgM antibody (anti‐A or cold agglutinin) was unable to confer monocyte‐mediated hemolysis, and that lysis was induced by IgG anti‐A antibody. In addition, IgG anti‐D sera containing antibodies belonging to subclass IgG1 or IgG3 had approximately equal hemolytic efficiency, as calculated from the antigen‐binding capacity of the sera at the concentrations inducing 50% monocyte‐mediated hemolysis. The lytic reaction was suppressed by pooled IgG or by individual myeloma proteins of subclass IgGl or IgG3. The inhibitory effect of heat‐aggregated IgG was not different from that of native IgG. IgG2 or IgG I had no or weak effects. Cross‐inhibition of lysis induced by IgG1 and IgG3 anti‐D antibody showed strong and equal suppression by IgG1 and IgG3 myeloma proteins. Hundredfold higher concentrations of IgG2 or IgG4 was required for inhibition of lysis, which may be an effect of contaminating IgGl or IgG3. Our data strongly suggest that the receptors on human blood monocytes for IgGl and IgG3 that participate in monocyte‐mediated hemolysis are identical.
Characterization of a Calcium‐Binding IgG Myeloma Protein
Authors: LINDGÄRDE F. , ZETTERVALL O.
Published: June 2006

A calcium‐binding IgG myeloma protein (A. L.) has previously been described It has now been characterized as an IgG1 lambda protein with two independent binding sites for calcium ions. The sites are localized in the Fab regions. Isolated heavy chains showed no unequivocal binding activity, whereas the light chains were active. The apparent intrinsic association constant for protein A.L., as found by equilibrium dialysis, was 104 l/mol.
Characteristics of the Interaction in Vitro Between Cytotoxic Thymus‐Derived Lymphocytes and Target Monolayers Infected with Lymphocytic Choriomeningitis Virus
Authors: ZINKERNAGEL R M. , DOHERTY P C.
Published: June 2006

Cell‐mediated lysis of target monolayers intccted with lymphocytic choriomeningitis virus has previously been shown to be a property of specifically sensitized thymus‐derived lymphocytes (T cells). The cytotoxic potential of individual effector lymphocytes is maximally expressed when infected monolayers are confluent and overlaying immune spleen cells cover less than the total target area. The data presented support the following interpretations [l] Cell‐mediated injury depends on close association between sensitized T cells and infected L cells. [2] Any attachment made is readily reversible. [3] Effector lymphocytes may damage more than one target cell, operating, perhaps, in a rather circumscribed area. [4] Cell death is a ‘one hit’ phenomenon. [5] Cytolysis is a property of individual T cells, there being no obvious requirement for co‐operation between different populations of spleen cells, [6] Substances secreted into the medium at large are neither directly cytotoxic nor capable of sensitizing normal spleen cells. [7] Specific lysis occurs at temperatures ranging from 27°C to 40°C, being maximal at the higher temperature
Lymphocyte Subpopulations in Chronic Lymphocytic Leukemia
Authors: MELLSTEDT H. , PETTERSSON D
Published: June 2006

Peripheral blood lymphocytes from eight patients with chronic lymphocytic leukemia (CLL) were studied. Characterization by different cell surface markers showed low percentages of lymphocytes that bound sheep erythrocytes and had receptors for activated human complement but markedly increased numbers of cells that carried surface immunoglobulins It is concluded that Ig‐bearing lymphocytes are mainly responsible for the lymphocytosis in CLL. The capacity of CLL lymphocytes to lyse 51Cr‐labeled chicken erythrocyte in vitro in the presence of phytohemagglutinin (PHA) or antibodies against target cells was reduced A strong correlation was found between the percentages of complement receptor‐bearing lymphocytes and their antibody‐induced cytotoxicity. The ability of CLL lymphocytes to synthetize DNA after stimulation with PHA or pokeweed mitogen (PWM) was reduced The impairment of stimulation was more pronounced at low concentrations of PWM than at high concentrations. This observation is in line with the assumption that low doses of PWM activate mainly bone marrow‐derived lymphocytes and that the normal B‐lymphocyte population is replaced by leukemic cells in CLL.
Effect of Neuraminidase on Lymphoid Cells
Authors: WIIG J. N.
Published: June 2006

After neuraminidase treatment the electrophoretic mobility of mouse lymphocytes (B and T cells) and thymocytes was reduced to a similar value, .a diminution of about 40%, 60%, and 40%, respectively. Thus B and T cells and thymocytes may have a common surface charge after removal of sialic acid. The percentage of cells binding anti‐thymocyte serum was not changed; thus sialic acid does not seem to be an important part of the specific antigen of lymphoid cells. Similar amounts of sialic acid were released from B and T Ceils, whereas less than half of this was released from the thymocytes. Thus, whereas thymocytes are characterized by their low electrophoretic mobility and low sialic acid release and T cells by high electrophoretic mobility and high sialic acid release, B‐cells in contrast show a low electrophoretic mobility and high sialic acid release.
Identification of Cell Surface Immunoglobulin Markers by Protein A‐Containing Fluorescent Staphylococci
Authors: GHETIE V. , NILSSON K , SJÖQUIST J
Published: June 2006

We describe a simple method for detecting surface‐associated IgG on some human lymphoid cell lines and on mouse lymphocytes. using fluorescent Staphylococcus aureus (strain Cowan 1). The adherence of the fluorescent bacteria to cell surface‐located IgG is mediated by protein A (SpA) molecules on the bacterial cell wall. Inhibition of the adherence of bacteria by soluble SpA was used for quantitation of IgG on cell surface. The method has a good specificity and a high sensitivity and detects approximately 600 IgG molecules per cell.
The Fractionation of Antigen‐Dependent Macrophage Migration Inhibition and Macrophage Activation Factors from Lymph Draining a Tuberculin Reaction
Authors: LOWE D. M. , LACHMANN P. J.
Published: June 2006

Efferent lymph, taken from BCG‐sensitized sheep 6 to 20 hr after inaction of PPD, was fractionated by chromatography on Sephadex G‐200 and on Sepharoseconcanavalin A and by rechromatography on Sephadex G‐200 The fractions were examined for their ability to inhibit the migration of normal guinea pig peritoneal exudate cells (MIF assay) and to stimulate the uptake of colloidal gold by these cells (GUS assay). Antigen‐dependent MIF activity and GUS activity eluted from Sephadex G 200 in the albumin fraction. No corresponding activities were found in this region when control lymph was fractionated in an identical manner. After chromatography on Sepharoseconcanavalin A, antigen‐dependent MIF activity was associated with a glycoprotein fraction containing IgG. After rechromatography on Sephadex G‐200, antigen‐dependent MIF and GUS activities eluted at a position corresponding with that of proteins of 60,000 to 70,000 molecular weight, and these fractions contained less than 2.5 μg/ml IgG. Soluble mediators produced in vivo by sheep with a delayed hypersensitivity response to PPD possessed antigen dependent MIF activity. The antigen‐dependent macrophage‐inhibiting and macro phage‐activating factors were closely associated in fractions that did not appear to contain significant amounts of IgG.