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Biomedical subjects

J D Feldman

Publications and source records attributed to J D Feldman.

At least 73 records · Page 4Linked to original sources
PubMed1975

Soluble membrane antigen fractions that react with rat enhancing alloantibodies.

Soluble extracts were prepared from cells of Brown Norway (BN) rat spleens by sonication in 2 M KI. Extracts were fractionated by gel filtration and electrophoretic procedures. The fractions specifically inhibited the binding of Lewis alloantibodies to target BN cells in vitro and in vivo. A homogeneous component that retained antigen activity was obtained by preparatory polyacrylamide gel electrophoresis. Lewis rats injected with BN antigen fractions produced histocompatibility alloantisera that would prolong the survival of BN skin grafts applied to Lewis neonates.

Animals↗
PubMed1975

Parturition-induced changes in maternal plasma cortisol levels.

Total maternal plasma cortisol levels were measured by a radioassay method in 9 patients who were in spontaneous labor and 10 patients who were electively induced at term with oxytocin. Determinations were made at onset of labor and repeated at full cervical dilatation. Total maternal plasma cortisol levels were also measured in 7 patients undergoing elective cesarean section without labor, determinations being made just prior to the procedure and at the time of uterine incision. Computerized analysis showed the mean initial cortisol level (+/- SE) in the spontaneous labor group (15.4 +/- 1.6 mug/100 ml) to be significantly less than the mean initial level of the group electively delivered by oxytocin induction (37.2 +/- 6 mug/100 ml), with P less than 0.01. The former value was also found to be significantly less than that of the group electively delivered by cesarean section (32.1 +/- 9.3 mug/100 ml), with P less than 0.05. A significant rise was noted at full cervical dilatation in the spontaneous labor group (P less than 0.05), whereas no change occurred in the two elective groups. No significant correlation was found between the maternal cortisol levels on the one hand and the cord cortisol levels. These findings indicate that a) maternal participation is unlikely in bringing about a surge of fetal plasma cortisol which is thought to precede spontaneous labor, b) elective termination of term pregnancy by oxytocin induction or cesarean section may be initially more stress-provoking to the mother than spontaneous labor, and c) maternal stress as measured by plasma cortisol level is not reflected in the fetus.

Adolescent↗
PubMed1975

The development of the retinotectal projection in Xenopus with one compound eye.

Double-nasal and double-temporal compound eyes were constructed in Xenopus embryos at stages 32 and 37/38. A particular half was removed from the host eye anlage and replaced with the opposite half-eye from the contralateral side of a donor embryo. Control operations consisted of removing a half-eye and replacing it with a similar half from the ipsilateral side of the donor embryo. Whereas in control animals, each half-eye projects its fibres to the appropriate half-tectum, in operated animals each half of the compound eye spread its optic terminals across the entire rostrocaudal extent of the dorsal tectal surface. The area of tectal surface covered by ganglion fibre terminals was similar in operated animals mapped at successive stages of development to that previously observed in normal animals at equivalent stages. Therefore the factors responsible for the extended distribution of fibre terminals from each half of a compound eye must exist at least from mid-tadpole life, and thereafter be continuously present throughout development.

Animals↗
PubMed1973

Thymus-dependent lymphocytes in tissue sections of rejecting rat renal allografts.

Lewis kidneys were grafted into BN recipients and examined at daily intervals up to 6 days after grafting with immunofluorescent reagents. A horse antiserum specific for T lymphocytes revealed an increasing number of T lymphocytes in the cellular infiltrates of rejecting allografts. These were detectable 1 day after grafting, reached a maximum 3 days later, and were relatively diminished at 6 days. In control isografts and nonimmunological inflammations of kidney, a small number of dispersed T lymphocytes was seen. A rabbit antirat thymocyte antiserum, given to allografted BN rats, prolonged survival of the grafts and decreased the cellular infiltrate and the number of T lymphocytes in the infiltrates. We conclude that in graft rejection there is a flow of T lymphocytes into areas of tissue damage and these T lymphocytes are immunologically reactive to graft antigens.

Animals↗
PubMed1973

The production of vesicular stomatitis virus by antigen- or mitogen-stimulated lymphocytes and continuous lymphoblastoid lines.

A variety of lymphoid cell populations were examined in terms of their ability to replicate vesicular stomatitis virus (VSV), a lytic, RNA-containing virus maturing at the cell surface. The number of cells capable of producing VSV was estimated in terms of infectious centers by the virus plaque assay (VPA), and morphologically by electron microscopy (EM). The lymphoid cells examined in this study included: (a) lymph node cells from delayed hypersensitive guinea pigs stimulated by specific antigen, (b) mouse spleen cells activated by selective bone marrow-derived (B) cell and thymus derived (T) cell mitogens, and (c) cells of human and murine continuous lymphoblastoid or lymphoma lines. In unstimulated cultures of guinea pig lymph node cells there is a background of approximately 1 in 1,000 cells which produces VSV; in purified protein derivative (PPD)-stimulated cultures the number of cells producing virus was 1.6% in the VPA and 1.9% by EM. These cells were large lymphocytes with some morphological features of transformed lymphocytes but were not typical blast cells. A few macrophages were associated with virus in both stimulated and control cultures. These observations indicate that (a) cells responsive to antigens, as detected by a marker virus, were lymphocytes; (b) cells other than lymphocytes (macrophages) were capable of replicating VSV even without antigenic stimulation; and (c) the correlation of results obtained by VPA and morphologic examination was usually quite good. Of the total number of mouse spleen cells stimulated with concanavalin (Con A), a T cell mitogen, 4.5 (EM)-5.7% (VPA) were associated with VSV. These were characteristic transformed lymphocytes, similar to phytohemagglutinin (PHA)-stimulated human lymphocytes. In contrast Escherichia coli lipopolysaccharide (LPS)-treated mouse spleen cultures contained lower numbers of virus plaque-forming cells. The majority of such cells associated with virus displayed extensive rough endoplasmic reticulum. Two cultured murine lymphomas containing lymphocytes with the theta surface marker (L5178Y and EL-4) showed a 15-100-fold higher incidence of virus-producing cells than leukemias (L1210 and C57Bl/6) which did not carry this marker. Similarly, the L2C guinea pig leukemia, a known B cell leukemia, yielded a low percent of virus plaque-forming cells (<2%). However, MOPC-104, a plasma cell tumor presumed to be of B cell origin, was found to be an efficient virus producer. There was a wide variation in the efficiency of VSV replication among human lymphoblastoid lines. One line, Wil-2, produced 80% infectious centers after 24 h of exposure to VSV, and all cells were associated with virus at the EM level. The relationship between the virus-producing cells and different lymphocyte subpopulations as well as the efficiency of the two assays for studying virus-producing lymphocytes is discussed.

Animals↗
PubMed1972

Cell-mediated cytotoxicity during rejection and enhancement of allogeneic skin grafts in rats.

Cell-mediated cytotoxicity (CMC) in spleens and lymph nodes of allografted rats was determined by release of (51)Cr from labeled target cells incubated with aggressor lymphoid cells. CMC was first detected in grafted adult rats on day 5, peaked on days 7 and 8, and declined rapidly to background levels by days 9 to 11. In allografted neonates and in cyclophosphamide-treated or neonatally thymectomized adults CMC was a fraction of that observed in normal adult rats. Enhancing antibodies deferred in vivo peak activity of CMC in allografted neonates for 3-4 days, and blocked in vitro the action of aggressor lymphocytes by binding to target cells. Enhancing antibodies had no effect on the cytotoxicity of aggressor cells, but horse antibodies to rat thoracic duct cells inhibited in vitro CMC of aggressor cells.

Animals↗
PubMed1972

Studies on the mechanism of fever accompanying delayed hypersensitivity. The role of the sensitized lymphocyte.

Experiments have been carried out to investigate the possible role of the sensitized lymphocyte in mediating the fevers of delayed hypersensitivity. Rabbits were made delayed hypersensitive to one of several heterologous proteins (bovine gamma globulin, bovine serum albumin, or human serum albumin) by footpad injection of antigen or antigen conjugated with dinitrophenol and incorporated in complete Freund's adjuvant. At intervals after sensitization, various tissues were removed, and single cell suspensions were incubated overnight with either carrier protein or conjugate in vitro. Release of an endogenous pyrogen (EP) was assayed by intravenous injection of the supernatant fluid into unsensitized rabbits. Of the tissues tested only those containing both lymphocytes and pyrogen-producing cells, blood, spleen, and draining lymph nodes, released detectable amounts of EP when incubated with antigen in vitro. Incubation of normal blood cells with specifically sensitized lymphocytes and antigen also resulted in significant release of pyrogen. Similarly, blood leukocytes released EP in vitro after mixture with supernates derived from incubation of sensitized lymphocytes and antigen. Cells and supernatant fluids from draining lymph nodes were usually effective in activating normal blood leukocytes earlier after sensitization than were those from mesenteric lymph nodes, suggesting that such cells, or antigen, had migrated from the original site of sensitization. The activator was soluble, nonpyrogenic in the dosages tested, and required incubation of viable cells with specific antigen for its production. These properties suggest that it may belong to the class of "lymphokines," biologically active agents released from lymphocytes that have been activated by immunologic or certain nonimmunologic stimuli.

Animals↗
PubMed1972

Production of macrophage migration inhibition factor by continuous cell lines.

Macrophage migration inhibitory factor (MIF) was found in media of human and mouse lymphocyte and fibroblast cell lines that were continuously growing. Its release was dependent on activation of the cells to enter the mitotic cycle, particularly on cells in S phase. The greatest quantity of MIF was detected in supernatants of lymphocytes collected during S phase after the cells were synchronized in G(1) and in supernatants of growing fibroblasts. When the latter were contact inhibited little or no MIF was found in media. MIF was also released into media of cells proliferating in homologous serum in the absence of fetal calf serum and into media lacking any protein. The MIF produced by lymphocyte lines eluted from Sephadex G-100 in the same fashion as MIF produced by the interaction of sensitized guinea pig cells and antigen. The results indicated that MIF is not a specific mediator of delayed hypersensitivity and cellular immunity and that MIF released by sensitized lymphocytes incubated with antigen merely reflects that fraction of cells activated by antigen to enter the mitotic cycle.

Animals↗