bluuebunny/crossref_metadata_2025_split huggingface dataset:
AN ULTRASTRUCTURAL STUDY OF GLOMERULAR PERMEABILITY USING CATALASE AND PEROXIDASE AS TRACER PROTEINS
Authors: Venkatachalam M. A. , Karnovsky M. J. , Fahimi H. D. , Cotran R. S. 
Published: June 2004

Mice were injected intravenously with beef liver catalase (mol wt 240,000) and very small doses of horseradish peroxidase (mol wt 40,000) and the site of localization of these enzymes in the kidney was studied by ultrastructural cytochemistry. 1 min after injection, catalase was present in glomerular capillary lumina and there was minimal permeation of the basement membrane. After 5–180 min, staining of the basement membrane increased progressively but was usually less than that in capillary lumina. At all time intervals the inner (sub-endothelial) layer of the basement membrane contained more reaction product than the lamina densa and the outer (subepithelial) layer. Catalase permeated the entire thickness of the basement membrane and extended up to the slit pore but not beyond the level of the slit diaphragm and was not seen in the urinary space or tubular lumina. Horseradish peroxidase permeated the whole thickness of the basement membrane within 2 min after injection; however, gradients of staining from the inner to outer layers of the basement membrane were frequently seen.
The findings with both enzymes indicate that (a) the basement membrane restricts the passage of proteins over a wide range of molecular size with increasing impediment for larger molecules and (b) the slit pore functions as an additional barrier for molecules that cross the basement membrane.
CELLULAR BASIS OF THE GENETIC CONTROL OF IMMUNE RESPONSES TO SYNTHETIC POLYPEPTIDES
Authors: Shearer G. M. , Mozes Edna , Sela Michael 
Published: June 2004

DBA/1 mice are high responders to the (Phe, G) determinant of the synthetic polypeptide (Phe, G)-Pro--L, whereas SJL mice respond well to the Pro--L region of this macromolecule (6). In order to determine whether the phenomenon described above is related to the number of antigen-sensitive units detected for both specificities, and whether responses to these determinants can be transferred independently, graded and limiting inocula of spleen cells from SJL, DBA/1, and F1 donors were injected into X-irradiated, syngeneic, recipient mice with (Phe, G)-Pro--L.
By this approach, one antigen-sensitive unit specific for (Phe, G) was detected in 1.7 x 106 and 8.5 x 106 spleen cells from immunized and nonimmunized DBA/1 donors, respectively. In contrast, one (Phe, G) relevant precursor was detected in 20 x 106 SJL spleen cells, irrespective of whether the donors had been immunized. On the other hand, for the Pro--L specificity, one limiting splenic precursor was found in 1.3 x 106 and in 3.4 x 106 cells for immunized and nonimmunized SJL donors, respectively; whereas one response unit was estimated for this determinant in 9.4 x 106 and in 38 x 106 spleen cells from immunized and nonimmunized DBA/1 mice. The findings reported here indicate that the phenotypic expression of the genetic control(s) for immune responsiveness to different immunopotent regions of (Phe, G)-Pro--L is directly correlated with the number of immunocompetent response units detected in two inbred mouse strains.
In the spleens of immunized F1 donors, similar frequencies of one limiting precursor in 3.0 x 106 and in 2.8 x 106 cells were detected for (Phe, G) and Pro--L, respectively. The results of a chi-square test for independence of (Phe, G) and Pro--L responses in F1 animals is compatible with the hypothesis that the transferred spleen cells limiting the response to (Phe, G)-Pro--L are restricted to generate antibodies specific for only one of the two determinants of this macromolecule.
STUDIES ON ANTIBODY-PRODUCING CELLS
Authors: Gudat Fred G. , Harris T. N. , Harris Susanna , Hummeler Klaus 
Published: June 2004

A study of the kinetics of antibody-producing cells has been carried out by the use of rosette formation for detection of individual antibody-producing cells, and labeling with tritiated thymidine, in cells obtained from mouse spleens at intervals after injection of SRBC. Following a primary injection of the antigen, the number of RFC per million cells was found to increase to a peak at 5 days, then, after a decrease, to a second peak at about the 10th day. The curve of tritium labeling of RFC was also biphasic, with peaks on the 3rd and 7th day. The second increase in rosette-forming cells could be shown to involve, especially between the 7th and 9th day, a second increase in lymphoid cell RFC and, among these, 7S antibody-producing cells. When the population examined was restricted to large lymphocytes, two peaks of RFC per million cells and two peaks of labeling were again found. In this case, however, the peaks of RFC and of labeling were reached on the same day in each instance, rather than with the 2 day difference found in the entire spleen cell suspension or the entire lymphoid cell population.
Electron microscopic examination of labeled rosette-forming cells showed these to be largely lymphocytes, but to include rather well differentiated plasmablasts as well. No macrophages were found among labeled RFC in the primary response. A substantial number of labeled lymphocytes were found in close contiguity with rosette-forming macrophages. The percentage of labeling in such lymphocytes was as high, on the respective days, as the percentage of labeled cells among the RFC of the entire suspension.
THE MOUSE INTESTINAL MICROFLORA WITH EMPHASIS ON THE STRICT ANAEROBES
Authors: Lee Adrian , Gordon James , Lee Chi-Jen , Dubos René 
Published: June 2004

The various components of the intestinal microflora in the mouse become established according to a definite time sequence; the strict anaerobes are the last groups of bacteria to reach their maximum population levels, 14–16 days after birth.
The multiplication of these strict anaerobes in the mouse intestine seems to depend upon the prior multiplication of other bacterial species, and coincides with the ingestion of food other than maternal milk. These two conditioning factors may correspond to the establishment of a suitably reduced Eh potential and to the provision of certain metabolites.
Once established, the strict anaerobes constitute by far the largest percentage of the total intestinal microflora; most of them are associated in a viable form with the mucosa. In normal animals they persist at very high levels throughout the life span. However, their populations can be drastically reduced by dietary manipulation of the animal, by administration of vancomycin, or by certain disease processes of the intestine.
The strict anaerobic bacteria seem to play an important, and perhaps essential role in the maintenance of the anatomic structures and physiological functions of the intestine. They also seem to hold in check several species of intestinal bacteria, in particular the coliform bacilli.
QUANTITATIVE STUDIES ON THE MIXED LYMPHOCYTE INTERACTION IN RATS
Authors: Wilson Darcy B. , Nowell Peter C. 
Published: June 2004

These studies were designed to determine what influence prior immunization with homologous H isoantigens might have on the subsequent proliferative activity of lymphocytes from these animals in the mixed lymphocyte interaction. The results demonstrate the following: (a) Subcutaneous immunization with splenic cells from donors differing at the major H locus accelerates the tempo of the proliferative response to F1 cells bearing these same antigens in the MLI, whereas antigen given systemically reduces the proliferative response. (b) The altered proliferative behavior is specific for the immunizing antigens. (c) The period after immunization during which the MLI displays an altered tempo is a short one, lasting not longer than 3 wk. (d) Whether they are derived from previously immunized or from normal donors, the proportion of lymphocytes responsive in the MLI is the same, even though the response profiles are different.
These results suggest that in comparison to immune responses to other types of antigens, immunologic reactivity to the major H isoantigens already involves a large number of antigen-reactive cells in normal animals and that the proportion of these cells is not increased as a result of immunization. Rather, lymphocytes from immunized animals respond more rapidly to the presence of these antigens.
MECHANISMS UNDERLYING BINDING OF IMMUNE COMPLEXES TO MACROPHAGES
Authors: Phillips-Quagliata Julia M. , Levine Bernard B. , Quagliata Franco , Uhr Jonathan W. 
Published: June 2004

The mechanism of binding of immune complexes to macrophages was investigated using purified antibody and haptens of different valences. Antibody alone bound to macrophages; enhancement of binding occurred when polyvalent and divalent haptens were present at equivalence but did not occur in great antigen excess. Monovalent hapten did not increase the binding of antibody at any concentration ratio tried, though it inhibited the enhancement due to oligovalent hapten. Ultracentrifuged normal rabbit globulin also inhibited the binding of complexes indicating the presence of exposed binding sites on the uncomplexed molecules. Complexes bound more strongly than antibody alone as determined from elution studies. These results support the hypothesis that the enhancement of antibody binding to macrophages in the presence of antigen is due to increased energy of binding resulting from summation of individual binding sites already exposed on the antibody molecules.
It was also possible, by saturating the macrophages with gamma globulin, to estimate the number of binding sites per cell; this was calculated to be approximately 2 million per alveolar macrophage.
AN EOSINOPHIL LEUKOCYTE CHEMOTACTIC FACTOR OF ANAPHYLAXIS
Authors: Kay A. B. , Stechschulte Daniel J. , Austen K. Frank 
Published: June 2004

The capacity of actively or passively sensitized guinea pig lung to react with antigen to release a factor specifically chemotactic for eosinophil leukocytes (ECF-A) has been demonstrated. The release of ECF-A was also accompanied by the elaboration of both histamine and SRS-A and the appearance of all these mediators exhibited a similar response in terms of the time course of passve sensitization, the effect of antigen dose, the time course of release, divalent cation dependence and enhancement by the presence of succinate or maleate. Decomplementation by the administration of purified cobra venom factor had no effect on the antigen-induced release of ECF-A from actively or passively sensitized lung fragments.
When fragments of guinea pig lung were passively sensitized with fractions of guinea pig 7S IgG, only the IgG1-containing fractions prepared tissue for the antigen-induced release of ECF-A. Histamine, SRS-A, bradykinin, serotonin, and the prostaglandins PGE1, PGE2, and PGF2α were not eosinophilotactic per se; neither was ECF-A detected following the incubation of these agents with sensitized lung in the absence of antigen.
Both eosinophilotactic activity and SRS-A survived extraction in 80% ethanol and evaporation to dryness. SRS-A, however, withstood boiling in alkaline solution for 20 min, whereas ECF-A activity was abolished by this procedure. SRS-A and ECF-A could also be separated by gel filtration. ECF-A activity was completely recovered following its passage through a column of Sephadex G-25 and had an estimated molecular weight of between 500 and 1000. On the basis of size and a formation mechanism independent of the complement system, ECF-A is distinguishable from a previously described complement-dependent eosinophilotactic factor (ECF-C). Thus, ECF-A represents a hitherto undescribed agent which selectively attracts eosinophil leukocytes.
MACROPHAGE PLASMA MEMBRANES
Authors: Nachman Ralph L. , Ferris Barbara , Hirsch James G. 
Published: June 2004

Plasma membranes have been isolated from pure populations of rabbit alveolar macrophages which were swollen in water, fixed briefly with glutaraldehyde, disrupted by Dounce homogenization, and separated by sucrose gradient centrifugation. The recovered membranes exhibited good structural preservation and enzymatic activity; both morphologic and biochemical evidence indicated a high degree of purity (&gt;90%) of the membrane preparation.
Interiorized plasma membranes were also prepared without exposure to glutaraldehyde from phagocytic vacuoles recovered from alveolar macrophages which had ingested large numbers of polystyrene spheres. These membranes were contaminated with lysosomal constituents, but they were nevertheless of value for comparison to the "pure" membranes isolated by the glutaraldehyde procedure.
Acrylamide gel electrophoresis of the solubilized plasma membranes and phagolysosomal membranes revealed similar protein patterns, with seven to nine individual components ranging in molecular weight from 70,000 to 140,000. The two most rapidly migrating components gave positive reactions for lipid as well as protein. A band containing carbohydrate was detected near the origin of the plasma membrane gels.
Antisera were made by injecting guinea pigs with the purified rabbit alveolar macrophage plasma membranes. Gel diffusion and immunoelectrophoretic study of these antisera established the presence of rabbit immunoglobulin G and of one or two other antigenic constituents in the membrane preparation.
REJECTION OF TUMOR ALLOGRAFTS BY MOUSE SPLEEN CELLS SENSITIZED IN VITRO
Authors: Cohen Irun R. , Globerson Amiela , Feldman Michael 
Published: June 2004

This paper reports a model system of cellular immunity in which allosensitization of mouse spleen cells is induced in vitro. Allosensitization was achieved by culturing spleen cells upon monolayers of allogeneic fibroblasts. The ability of the spleen cells to inhibit the growth of tumor allografts in vivo served as a functional assay of sensitization. We found that unsensitized spleen cells or spleen cells sensitized against unrelated fibroblast antigens had no inhibitory effect on the growth of allogeneic fibrosarcoma cells when they were injected together into irradiated recipients. In contrast, spleen cells which were specifically allosensitized in vitro were found to be highly effective in inhibiting the growth of an equal number of allogeneic tumor cells. Several times more spleen cells from mice sensitized in vivo were required to produce a similar immune effect. This confirms the findings of previous studies which indicate that sensitization in cell culture can promote the selection of specifically sensitized lymphocytes.
Preincubating sensitizing fibroblasts with allo-antisera blocked the allosensitization of spleen cells. This suggests that antibodies binding to fibroblasts may inhibit the induction of sensitization by competing with lymphocytes for antigenic sites.
Mouse spleen cells which were able to recognize and reject tumor allografts in vivo were unable to cause lysis of target fibroblasts in vitro. Such fibroblasts, however, were susceptible to lysis by rat lymphoid cells sensitized by a similar in vitro method. These findings indicate that the conditions required for lymphocyte-mediated lysis of target cells may not be directly related to the processes of antigen recognition and allograft rejection in vivo.
THE PHLOGISTIC ROLE OF C3 LEUKOTACTIC FRAGMENTS IN MYOCARDIAL INFARCTS OF RATS
Authors: Hill Jeffrey H. , Ward Peter A. 
Published: June 2004

An improved method is described for extraction from rat myocardium of an enzyme that cleaves the third component of complement (C3) into leukotactic fragments. Direct cleavage of C3 has been shown by the use of a radiolabeled preparation of human C3. The enzyme elutes slightly beyond (retarded to) an albumin marker in gel filtration.
After surgical ligation of a coronary artery, leukotactic activity can be extracted from infarcted rat myocardium. Described in terms of its time of appearance in infarcted tissue, the leukotactic activity has been identified as cleavage products of rat C3. The C3 fragments are of low molecular weight and heterogenous in size.
Rats, if treated with the C3 inactivator (isolated from cobra venom) so as to ablate serum C3, fail to develop leukotactic activity in the infarcted myocardium. In turn, few if any of the usual intense accumulations of neutrophils in response to infected myocardium are seen during the first 48 hr after coronary artery ligation.
These studies suggest a nonimmunologic role for C3 in the mediation of the acute inflammatory response in nonspecific tissue injury.
THE FACTOR OF IMMUNIZATION IN THE RAT
Authors: Ford William L. , Simonsen Morten 
Published: June 2004

Using a popliteal lymph node weight assay the graft-versus-host activity of lymphocytes from donors immunized with allogeneic tissue has been assayed by comparison with that of lymphocytes from nonimmune donors. When the donors were immunized against weak histocompatibility antigens (non-AgB) the specific GVH activity of its lymphocytes was increased. This increase was greater if spleen cells rather than thoracic duct lymphocytes were the source of the donor cells used for assay. The increase in GVH activity was also greater if the standard immunization procedure of two successive skin allografts was followed by three boosting injections of allogeneic lymphoid cells.
When donors were immunized against strong histocompatibility antigens the specific GVH activity of the donors' lymphocytes was slightly increased, was unchanged, or was actually decreased depending on the experimental situation. In donors rendered incapable of a humoral alloantibody response by whole body X-irradiation, immunization across a strong barrier was followed by little or no increase in the specific GVH activity of TDL. In the rat, as in other species, the increase in GVH activity after immunization is inversely proportional to the strength of the antigenic barrier involved.
THYMUS-MARROW IMMUNOCOMPETENCE
Authors: Cohen J. John , Claman Henry N. 
Published: June 2004

Corticosteroids suppress the humoral antibody response of mice to sheep erythrocytes. This response depends on interactions between thymus-derived helper cells and bone marrow-derived antibody-forming cell precursors (AFC precursors). Previous experiments had shown that spleen cells (a mixture of thymus-derived and marrow-derived cells) were sensitive to corticosteroids while AFC precursors in the bone marrow were resistant. The present experiments showed that the thymus of a mouse given 2.5 mg of hydrocortisone acetate, although containing only about 5% of the number of cells of a normal thymus, was as effective as a normal thymus in cooperating with bone marrow when transferred to irradiated syngeneic mice and stimulated with SRBC. The proliferative response of thymus helper cells to SRBC was also resistant to hydrocortisone.
In this context, the majority of thymic cells are in the cortex, are rapidly dividing, are sensitive to corticosteroids and are not iminunocompetent. A small number of thymic cells, probably located in the medulla, are resistant to corticosteroids, but are immunocompetent since they can serve as helper cells.
The hydrocortisone-sensitive phase of the splenic response to SRBC was found to be the bone marrow-derived AFC precursor since spleens from hydrocortisone-treated donors had immunocompetence restored by normal bone marrow but not by normal thymus cells.
FURTHER STUDIES OF ANTIGENIC COMPETITION
Authors: Kerbel R. S. , Eidinger David 
Published: June 2004

A striking correlation between the capacity of an antigen to nonspecifically suppress humoral immune responses of subsequently administered antigens which are non-cross-reacting, i.e. to manifest antigenic competition and produce enlargement of spleen size through cell proliferation, was found. Increase in spleen size was always accompanied by a drop in the normal proportion of thymus-derived cells to non-thymus-derived cells.
Various means of altering the immune response to the initial antigen, and hence, the capacity of that antigen to suppress in a model of antigenic competition were performed and correlated with changes in spleen size and in the proportion of θ-positive cells in the spleen. In all instances, when the experimental condition reduced or abolished antigenic competition, the increase in spleen size and reduction in the proportion of θ-positive cells in the spleen was reduced or abolished. Furthermore, under conditions in which the suppressive capacity of the initial antigen was unaltered, the increase in spleen size and reduction in θ-proportion occurred normally. Finally, the better the suppression in a model of antigenic competition, the greater the increase in spleen size and reduction in the proportion of θ-positive cells.
On the basis of these observations, it appears that there is a relationship between spleen enlargement through clonally restricted cell proliferation and the expression of antigenic competition; one cannot have the latter without the former. It is postulated that the immunological lesion associated with antigenic competition resides at the level of interference with cell interaction between thymus-derived antigen-reactive cells and marrow-derived antibody-forming cells. This occurs as a result of a relative "diluting out" of cells of both populations carrying antigenic specificity differing from the one(s) which induced the dilution effect in the first place. The net effect of this is to decrease the chance of a "hit" or interaction between a marrow-derived and thymus-derived cell of the same specificities.
This mechanism, which is compatible with theories of clonal selection, and which in fact is dependent upon them, supports the view that the term "antigenic competition" is a misnomer; there is no competition by the antigens for anything. The term "antigen-induced suppression" is suggested as a more suitable alternative.
STUDIES ON THE LIFE HISTORY OF LYMPHOCYTES
Authors: Nowell Peter C. , Wilson Darcy B. 
Published: June 2004

The life history, within the rat, of lymphocytes responsive to histocompatibility isoantigens in the mixed lymphocyte interaction was examined by the use of in vivo labeling with tritiated thymidine and radioautography. Lymphocytes in the peripheral blood and H-ARC (mitotic figures in the MLI) were compared with respect to the frequency of labeled cells and the median grain count. The following conclusions were drawn from this study: (a) Although some can be considered long-lived, the majority of H-ARC are the products of recent divisions in the body. (b) Adult thymectomy does not eliminate the production of long-lived lymphocytes, some of which are H-ARC. Hence, in addition to direct origin in the thymus, H-ARC, as well as other lymphocytes of the long-lived lymphocyte population, may derive from already existing thymus-derived cells in the circulation and thymus-dependent areas of the secondary lymphoid tissues. (c) Sublethal X-irradiation (600 R) in combination with adult thymectomy does not eliminate the capacity to produce some long-lived lymphocytes, however, few if any are H-ARC. (d) H-ARC and other long-lived lymphocytes appear to go through a series of rapid multiple divisions before they enter the circulation. Thereafter, long-lived lymphocytes appear to undergo intermittent single divisions which decrease both the frequency and median grain count of labeled cells gradually with time. On the other hand, labeled H-ARC maintain a more stable grain count despite a rapid decrease in frequency with time. This is taken to indicate that H-ARC are less likely to undergo occasional single divisions during their life-span, but may undergo periodic rapid sequential divisions.
A speculative model is developed from these data on the life history of H-ARC which may be of predictive value in future studies and which can be tested against known facts.