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Biomedical subjects

M Feldman

Publications and source records attributed to M Feldman.

At least 307 records · Page 17Linked to original sources
PubMed1985

Technicium as a radiolabel in the assessment of in vivo human Fc clearance.

99m-Tc was used as a radiolabel to study in vivo human clearance of IgG sensitized erythrocytes. Stannous chloride pretreatment at different doses and varying amounts of 99m-Tc were studied with respect to radiolabelling efficiency and elution. Mean in vivo clearance rates in systemic lupus erythematosus patients were significantly prolonged compared to controls. Using as little as 200 microCi of 99m-Tc per patient, in vivo human immune clearance can be determined with a minimal radiation biohazard. With this method, serial immune determinations can be performed within very short time frames, allowing for monitoring effects of immunomodulatory therapy as well as variations in disease activity.

Erythrocytes↗
PubMed1985

Proteolytic enzymes in tumor metastasis. II. Collagenase type IV activity in subcellular fractions of cloned tumor cell populations.

Collagenase type IV degradation activity was examined in metastatic and nonmetastatic clones of the Lewis lung carcinoma (3LL) and of the T10 sarcoma. Conditioned media prepared from cells of both tumors grown in vitro contained low degradation activities, whereas conditioned media from organ cultures of the same clones grown as solid tumors in animals exhibited higher degradation activities. Analysis of subcellular fractions of tumor cells showed that collagenase type IV activity was localized mainly in the cytoplasmic fraction. Crude homogenates or detergent lysates manifested low degradation activities. Little activity was associated with purified plasma membrane preparations and endoplasmic reticular fractions. However, addition of plasma membrane to conditioned media and to cytoplasmic fractions reduced the degradation activities of the cytoplasmic fractions. Possibly a factor that inhibits collagenase type IV exists in the cells in a vesicular form. No correlation between degradation activity and metastatic capacity was demonstrated in the models used in this study. Both metastatic and nonmetastatic clones of the same tumor similarly could degrade basement membrane components.

Animals↗
PubMed1985

Proteolytic enzymes in tumor metastasis. I. Plasminogen activator in clones of Lewis lung carcinoma and T10 sarcoma.

Plasminogen activator (PA; urokinase) levels were studied in metastatic and nonmetastatic clones of the Lewis lung carcinoma (3LL) and of the T10 sarcoma. Tests of clones grown in vitro revealed that the cell content and secretion of PA correlated positively with the metastatic capacity of the clones of both tumors. When cell-associated activities were examined in cloned cell populations grown subcutaneously in vivo, the apparent activities in the solid tumors produced by low-metastatic clones were equal to or even higher than those in solid tumors produced by high-metastatic clones. This finding was attributed to the observation that solid tumors produced by low-metastatic clones, but not those produced by high-metastatic clones, were highly infiltrated with macrophages. Subsequent tests indicated that the ip inoculation of X-irradiated or mitomycin-treated tumor cells of low-metastatic clones elicited a significantly greater peritoneal infiltration of macrophages than did tumor cells of high-metastatic clones. Such "tumor-associated" macrophages manifested high levels of PA, whereas resident (nonactivated) peritoneal macrophages did not. These findings suggest that although PA may cause the initial detachment from the local tumor of both nonmetastatic (via the macrophage PA) and metastatic cells (via their own PA), the PA secreted by the metastatic cells may enable them to complete subsequent stages of the metastatic process that may be PA-dependent.

Animals↗
PubMed1985

Effects of platelet-derived growth factor and epidermal growth factor on antigen-induced proliferation of human T-cell lines.

When the serum content of tissue culture medium is reduced from 10% to 1%, the capacity of T cells to proliferate in response to antigen within that medium is dramatically reduced. Physiological concentrations of platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) are able to partially replace the requirement for serum, in that they are able to increase antigen-driven T-cell proliferation at a serum concentration of 1%. Neither growth factor is mitogenic for T cells in the absence of antigen, and neither is able to act synergistically with T-cell growth factor (TCGF) or IL-2) in the absence of antigen. Antigen-presenting cells (APC) pulsed with antigen in the presence of PDGF or EGF are able to stimulate antigen-specific T-cell proliferation to a greater extent than antigen-presenting cells pulsed in the absence of exogenous PDGF or EGF. Both growth factors increase the expression of MHC Class II antigens on antigen-presenting cells.

Antigen-Presenting Cells↗
PubMed1985

Heterogeneity of human natural killer cells.

The cell surface antigens and specificity of cultures of human natural killer (NK) cells, propagated in the presence of interleukin 2, were analyzed at the single-cell level. With the use of a micropipette isolation procedure, clones were initiated from cells of defined phenotype. The cell surface markers on the resultant clones were not stable and often diverged from those on the cells selected for initiation. Clones manifesting NK activity had low expression of T4 and T8 and most had some expression of T10, whereas clones without detectable cytotoxic activity had a considerable proportion of cells expressing T4 and/or T8 antigens. Within a cytotoxic clone, single cells shown to have killer activity were shown to express often T10 and infrequently T8; T4 was not detected on any of the reactive cells examined. The NK, reactive cells were found to express also antibody-dependent cell-mediated cytotoxicity and lectin-dependent cell-mediated cytotoxicity (LDCC), and some of the individual NK cells were shown to have the ability to lyse more than one type of target cell. However, there appeared to be considerable heterogeneity among the cells in the clones, with only 50-60% of cells displaying lytic activity against K562 cells at a given time. In addition, one cytotoxic clone appeared to have specific immune alloreactivity as well as NK and LDCC activities. The results of this study indicated that the cell surface phenotype and specificity of cytotoxic reactivity of cultured human NK cells were heterogeneous and suggested that such heterogeneity may be due to variations in the levels of differentiation and/or activation.

Cell Differentiation↗
PubMed1985

Selecting, accelerating and suppressing interactions between macrophages and tumor cells.

Studies were carried out to test whether thioglycollate-induced macrophages (T-PM phi) exert a selective effect on 3LL tumor cells. One million 3LL tumor cells and 10 X 10(6) thioglycollate-elicited peritoneal macrophages were admixed and inoculated subcutaneously in C57BL/6 mice. This procedure was repeated for a series of 6-15 consecutive transplant generations. After 6 generations, the tumor cells which were selected in this manner (3LLR6) grew faster in vivo and in vitro when admixed with T-PM phi than 3LL cells which were not selected by T-PM phi. However, in vivo, this T-PM phi-mediated acceleration of 3LLR6 tumor growth was followed by tumor rejection and induction of anti-3LL immunity. Intravenous inoculation of T-PM phi enhanced the growth of pulmonary metastases in mice subsequently inoculated intravenously with 3LL cells. Such T-PM phi-mediated augmentation of metastases was not observed with 3LLR6 cells. Homing of 3LL and 3LLR6 cells to the lungs after pretreatment with T-PM phi was similar, indicating that these cells did not differ in their capacity to colonize the lungs but rather in subsequent tumor growth. Additional transplantations of 3LLR6 cells with T-PM phi led, after 9 further transplant generations, to a different tumor cell, 3LLR15, with completely new morphological, tumorigenic and metastatic properties. Unlike the 3LLR6 cells, this variant was not sensitive to the growth promoting effects of T-PM phi. Furthermore, it expressed the H-2K-and H-2D-encoded antigens of the H-2b haplotype, whereas the 3LL and 3LLR6 cells expressed only the H-2D alloantigens. This indicates that macrophages may either exert a selective effect on tumor cells or play a role in the induction of new tumor cells.

Animals↗
PubMed1985

Metastatic capacity of cloned T10 sarcoma cells that differ in H-2 expression: inverse relationship to their immunogenic potency.

Clones of the T10 sarcoma, originated in a (H-2b X H-2k)F1 mouse, differ in their metastatic competence, correlated with differences in the expression of antigens of the two parental haplotypes. In fact, the metastatic phenotype is determined by the H-2Dk antigen. Whether the different major histocompatibility complex gene products control the metastatic phenotype via their different immunogenic properties was tested. The involvement of the immune system in controlling the development of metastases was inferred from experiments in which nonmetastatic T10 cloned cells were found to produce both experimental and spontaneous metastases in syngeneic immune-suppressed mice. After the testing of T-cell-mediated immune responses, metastatic T10 cloned cells, which expressed the H-2Db and H-2Dk antigens, were nonimmunogenic in their syngeneic hosts, whereas nonmetastatic T10 cloned cells, which expressed predominantly the H-2Db antigens, evoked a strong T-cell response. H-2Db and H-2Dk antigens expressed on T10 cells appeared to differ in their immunogenicity. This was further supported by the observation that whereas a good antibody response was elicited by H-2Db antigens expressed on T10 cells, only a low anti-H-2Dk antibody was produced. The different T10 cloned cells were not susceptible to natural killer (NK) activity in an in vitro assay, yet in vivo studies suggested the participation of NK activity in controlling T10 metastasis. In animals with depressed NK activity, metastases were generated even by nonmetastatic clones, whereas in animals in which NK activity was elevated, even metastatic clones failed to generate metastases. Both T-cell-mediated immune responses, probably restricted by the H-2D products and NK reactivity, appeared to participate in controlling the development of metastases by T10 cells.

Animals↗
PubMed1985

The importance of leukocyturia in young adults.

The records of 1,000 asymptomatic male air force personnel were examined retrospectively for the results of 15 yearly examinations (1968 through 1983) of urinary sediment, beginning with subjects aged 18 to 33 years. The cumulative incidence of four to six or more WBCs per high-power field on one or more examinations was 31.8% after an average of 12.2 examinations per person over the 15-year period. In 107 subjects the WBCs were found on two or more occasions within five consecutive examinations. In 106 subjects, 140 urine cultures were sterile. In 28 cases the urine was also sterile after culture for Mycobacterium tuberculosis. Intravenous pyelograms, obtained in eight cases, were normal. Renal biopsy in one case with recurrent hematuria and trace proteinuria showed focal glomerulonephritis. All subjects are currently active and free of urinary symptoms an average of 7.6 years after detection of leukocyturia.

Adult↗
PubMed1984

Generation of invasive and metastatic variants of a non-metastatic T-cell lymphoma by in vivo fusion with normal host cells.

Intravenous inoculation of the AKR mouse-strain-derived BW lymphoma into CBA recipients resulted in a case of liver metastasis; cells derived from this metastatic nodule were termed BW-Li cells. BW-Li cells, upon reinoculation, generated metastases in the spleen, liver, kidney and ovaries in 100% of CBA recipients. Furthermore, BW-Li cells, in contrast to BW cells, were found to infiltrate in vitro monolayers of hepatocytes, thus confirming their inherent invasive potential. Analysis of the alloantigenic phenotype of BW-Li cells revealed that such cells were Thy 1.1+, Thy 1.2+, Lyt 1.2+, Lyt 1.1-, Lyt 2- and H-2Dk+, as compared to BW cells which exhibited the membrane phenotype Thy 1.1+, Thy 1.2-, Lyt 1.2-, Lyt 1.1-, Lyt 2-, H-2Dk-. BW-Li cells also differed functionally from BW cells since these cells secreted IL-2 upon stimulation with Concanavalin A. BW tumor transplantation experiments were repeated in a semi-allogeneic F1 strain combination, i.e. (AKR X CBA)F1, and again a case of massive liver metastasis was observed. Cells derived from these liver metastases (termed BW-O-Li) manifested an invasive and metastatic potential similar to that of BW-Li cells. Furthermore, BW-O-Li cells secreted IL-2 upon stimulation with Con A and manifested the following alloantigenic phenotype: Thy 1.1+, Thy 1.2+, Lyt 1.2+, Lyt 1.1-, Lyt 2-, H-2Dk+ and H-2Kk+. These results indicate that BW-Li and BW-O-Li cells are functional T-cell hybrids which express T-cell markers derived from BW cells and Thy 1.2+ CBA host cells. The acquisition of host-derived T-cell properties may have led to the expression of metastatic and invasive capabilities. From these results we conclude that the acquisition of metastatic properties following somatic cell fusion with normal lymphoreticular cells may represent a mechanism for tumor progression in vivo.

Animals↗
PubMed1984

HTLV-III in cells cultured from semen of two patients with AIDS.

Epidemiological results suggest that the etiological agent of the acquired immune deficiency syndrome (AIDS) is transmitted primarily through blood products, semen, and saliva. There is evidence that the human T-cell leukemia (lymphotropic) virus type III (HTLV-III) is this agent. HTLV-III has been isolated repeatedly from T cells obtained from peripheral blood or lymph node tissue of AIDS and pre-AIDS patients and of healthy people believed to have been exposed to the virus. In the present study, HTLV-III was detected in and isolated from T cells present in the seminal fluid of AIDS patients. Mononuclear cells from the semen of AIDS patients and normal individuals were cultured in the presence of T-cell growth factor (interleukin-2). After 6 to 8 days, HTLV-III antigens were transiently expressed by the cells from the AIDS patients but not by those from the normal individuals. When the mononuclear cells from the semen of AIDS patients were cocultured with a permissive human T-cell line, cell cultures were produced that expressed high levels of reverse transcriptase activity, showed retroviral particles by electron microscopy, and were positive for HTLV-III-specific antigens when tested by fixed-cell indirect immunofluorescence with the use of monoclonal antibodies to the p24 and p15 antigens of HTLV-III.

Acquired Immunodeficiency Syndrome↗
PubMed1984

The differential expression of H-2K versus H-2D antigens, distinguishing high-metastatic from low-metastatic clones, is correlated with the immunogenic properties of the tumor cells.

Two clones of the 3LL Lewis lung carcinoma, a low-metastatic clone A9 and a high-metastatic clone D122, were studied for MHC expression and immunogenic properties. Using monoclonal antibodies, we demonstrated that the A9 clone expresses both the H-2Kb and the H-2Db, whereas the D122 expresses only the H-2Db, and lacks the expression of the H-2Kb encoded molecules. Cells of the low-metastatic clone A9 grew progressively in syngeneic (C57BL/6J) or in F1 mice, but were rejected in allogeneic recipients. The high-metastatic D122 grew progressively in all mouse strains tested, yet metastases were formed only in syngeneic recipients. When H-2 recombinant mice were used, the A9 again manifested a significantly greater immunogenic potency than the metastatic D122, which grew in all 4 recombinants tested. Metastases, however, were formed in B10HTG and to a lesser extent in B10A(4R), thus indicating that metastasis formation is restricted by both C57BL background and H-2Db sub region. We subsequently tested whether the higher immunogenicity of the H-2Kb-positive A9 cells is expressed also in syngeneic mice, to examine whether this could account for its low metastatic phenotype. We found that immunization by A9 cells significantly inhibited the growth of a subsequent A9 graft and even of D122, yet D122 did not retard the growth of secondary D122 or A9 cells. The increased immunogenic effect was expressed also in the generation of syngeneic cytotoxic lymphocytes by A9 but not by D122 cells. We suggest that expression of H-2K molecules on the 3LL clones, immunogenicity and the metastatic phenotype are causally related in this system.

Animals↗
PubMed1984

Immuno-selection in vivo of H-2D phenotypic variants from a metastatic clone of sarcoma cells results in cell lines of altered metastatic competence.

To find out whether manipulation of H-2 expression on metastatic cells could alter their metastatic properties, we immunoselected in vivo H-2 antigen variants from a metastatic clone of the T10 sarcoma [originating in a (C57BL/6J X C3H.eB)FI mouse] and tested their metastatic capacity. The unselected metastatic cells (IE7) were previously found to express H-2Db and H-2Dk antigens, but they did not express the H-2K antigens of either parental haplotype. Transplantation of IE7 cells into C57BL/6J irradiated mice resulted in loss of H-2Dk expression and a reduction in H-2Db antigen density. Further transplantation of these cells into non-irradiated C57BL/6J mice led to a total loss of H-2 expression. The cells concomitantly lost their metastatic potency. Immunoselection of IE7 cells in C3H.eB irradiated and non-irradiated mice resulted in cells which were H-2Dk-positive but H-2Db-negative. Cells of these selected variants not only retained their metastatic potential, but in fact were far more metastatic than the unselected IE7 cells. Thus, changes in H-2 expression on tumor cells may alter their metastatic potential. In the case of T10 cells, H-2Dk expression seems to be directly involved in their metastatic capacity.

Animals↗
PubMed1984

Receptor-mediated endocytosis of tuftsin by macrophage cells.

A fluorescent analog of the phagocytosis stimulating peptide tuftsin was prepared by coupling tetramethyl rhodamine isothiocyanate to a C-terminal elongated derivative of tuftsin. This analog, Thr-Lys-Pro-Arg-Gly-Lys(N epsilon-tetramethyl rhodamine)-OH, was used to visualize tuftsin receptors on mice macrophage cells by fluorescent image intensification. Fluorescent labelling was carried out at 37 degrees C, using a concentration of 200 nM and 2 microM of the fluorescent tuftsin derivative. The formation of peptide-receptor clusters and their subsequent internalization, as discerned by image intensification, were rapid processes, 5 min and 5-30 min, respectively. Preincubation of macrophages with tuftsin for various time intervals, followed by quantification of the tuftsin receptor using radiolabelled tuftsin, suggest that tuftsin receptors are initially increased in amount (5-7 min) and subsequently reduced (after 10-15 min) as judged by sites available for tritiated tuftsin. The binding studies are rather complementary to the fluorescence observations and support the assumption that the tuftsin receptor on the membrane of the mice macrophage cell is rapidly mobilized.

Animals↗
PubMed1984

Nonmetastatic tumor cells acquire metastatic properties following somatic hybridization with normal cells.

Somatic cell hybridization between nonmetastatic tumor cells and normal cells of the lymphoreticular system results in hybrid cells manifesting metastatic properties of defined target organ specificity. Thus, fusion of the nonmetastatic BALB/c originated NSI plasmacytoma with C57BL B lymphocytes resulted in hybridomas, each of which were metastatic. Of 10 hybridomas, 7 generated metastases in the spleen and liver, whereas 3 generated liver metastases. The generation of liver metastases by hybridomas which homed to both spleen and liver, but not by those which homed to the liver only, was controlled by the spleen. The acquisition of metastatic properties via somatic cell fusion seems to represent a general principle, in which the normal partner determines the target organ specificity for the metastatic growth. Thus, fusion of SP2/O myeloma cells with syngeneic B lymphocytes also resulted in a hybrid cell metastasizing to the spleen and liver, yet a somatic hybrid between NSI and a macrophage or dendritic-like cell metastasized to the lung. Cell surface molecules encoded by the genome of the normal partner was demonstrated to control the target organ specificity: antibodies against MHC-encoded antigens of the normal B cell partner prevented the generation of metastases by hybridomas metastasizing to the spleen and liver, but not by those metastasizing to the liver only. This is in accordance with the function of MHC molecules on lymphocytes in controlling their homing to lymphoid organs. Hybridomas of T cell lymphomas also manifested metastatic properties. Analysis of the cell surface Thy-1 antigens of a hybridoma (DCH10), produced via somatic fusion between BW5145 lymphoma and a putative macrophage cell indicated that cells of liver metastases (DCH10-Li) generated by the hybrid cells might have undergone further somatic cell fusion in vivo with host (T?) cells. These cells have acquired new metastatic properties, generating metastases in spleen, liver and kidneys. In fact, even the inoculation of the parental BW lymphoma cells resulted in a case of liver metastasis (BW-Li). Such BW-Li cells, upon reinoculation, also generated metastases in the spleen, liver and kidneys. Analysis of the Thyl phenotype indicated that BW-Li cells may also have undergone somatic cell fusion in vivo with host (T?) cells, resulting in the acquisition of metastatic properties. The pattern of cell-cell interactions (adhesion, infiltration) with liver cell monolayers of BW-Li cells and of DCH10-Li (T-cell lymphomas) was identical, and differed from cells of liver metastases of the myeloma-B cell hybridomas which might be based on responses to liver growth signals.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Traveler's diarrhea.

Three hundred million people, mostly tourists, participate in international travel each year. Development of an acute diarrheal syndrome abroad, while returning home, or shortly after arriving home is referred to as traveler's diarrhea (TD). TD is not a specific diagnosis but, rather, a clinical syndrome with multiple etiologies. In this article, clinical and epidemiological features of TD, specific etiologies and their pathogenesis, as well as current means of diagnosis, treatment, and prevention will be reviewed.

Anti-Bacterial Agents↗
PubMed1984

Effect of chronic sham feeding on maximal gastric acid secretion in the dog.

The reason for increased maximal acid secretory capacity in some patients with duodenal ulcer is uncertain. We postulated that chronically increased cephalic-vagal stimulation may be a cause of increased maximal acid output. To study this, we prepared six male, mongrel dogs with a vagally innervated gastric fistula, a vagally denervated fundic (Heidenhain) pouch, and a cervical esophagostomy. Physiological cephalic-vagal stimulation was accomplished by sham feeding, which increased acid output from the vagally innervated stomach but not from the vagally denervated pouch. During an initial 6-wk control period, dogs were fed by mouth once daily at 3 p.m. Then, a 6-wk period of sham feeding was carried out, during which animals were sham fed with blenderized dog chow from 8 a.m. to 3 p.m. every day (a 7-h period of continuous cephalic-vagal stimulation), after which animals were fed by mouth. After 6 wk of daily sham feeding, maximal acid output in response to intravenous pentagastrin (16 micrograms/kg per h) increased by 27 +/- 4% in the vagally innervated stomach (P less than 0.01). Maximal acid output then returned to control levels after a final 6-wk recovery period with no sham feeding. No changes in maximal acid output occurred in the vagally denervated pouch during the 18-wk study. No changes in basal acid secretion or responsiveness of parietal cells to submaximal doses of pentagastrin occurred in the fistula or pouch during chronic sham feeding. We conclude that chronic physiological cephalic-vagal stimulation can increase maximal acid secretory capacity. Our studies also suggest that the effect of chronically increased vagal stimulation on maximal acid secretory capacity is reversible.

Animals↗
PubMed1984

Role of circulating somatostatin in regulation of gastric acid secretion, gastrin release, and islet cell function. Studies in healthy subjects and duodenal ulcer patients.

Studies were designed (a) to determine whether somatostatin is released into the circulation after meals in sufficient amounts to regulate gastric or pancreatic islet function in humans and (b) to investigate the possible role of somatostatin in the pathogenesis of duodenal ulcer disease. Mean plasma somatostatin-like immunoreactivity (SLI) increased from 6.2 +/- 1.5 pg/ml to a peak level of 13.8 +/- 1.3 pg/ml in eight healthy subjects after a 1,440-cal steak meal (P less than 0.005). When somatostatin-14 was infused intravenously, basal and food-stimulated gastric acid secretion and also basal and food-simulated plasma insulin and glucagon concentrations were reduced significantly at mean plasma SLI concentrations within the range seen after a meal. Thus, the amount of somatostatin reaching the systemic circulation after a steak meal was sufficient to inhibit gastric acid secretion and islet cell function. On the other hand, basal and food-stimulated plasma gastrin concentrations were reduced by intravenous somatostatin only at plasma SLI concentrations that were several-fold greater than post-prandial SLI concentrations. Although duodenal ulcer patients had significantly higher basal, food-stimulated, and peak pentagastrin-stimulated gastric acid secretion rates than healthy controls, duodenal ulcer patients and controls had nearly identical basal and food-stimulated SLI concentrations. Moreover, food-stimulated gastric acid secretion and gastrin release were inhibited by intravenous somatostatin to the same extent in ulcer patients and controls. These studies suggest that duodenal ulcer patients release normal amounts of somatostatin into the circulation and that target cells controlling acid secretion and gastrin release are normally sensitive to somatostatin in these patients.

Adult↗