Biomedical subjects

J S Hunt

Publications and source records attributed to J S Hunt.

At least 109 records · Page 6Linked to original sources

PubMed1989

Ontogeny and distribution of cells expressing HLA-B locus-specific determinants in the placenta and extraplacental membranes.

Both the trophectoderm and the inner cell mass of the blastocyst contribute to the cell populations found in the placenta and extraplacental membranes. Previous studies have shown differences between those two embryologically distinct populations of cells in their expression of class I HLA, and further differences among trophectoderm-derived trophoblast cell subpopulations. Binding patterns for antibodies to both monomorphic and allotypic determinants on class I heavy chains have been reported. In the present study, extraembryonic cells were evaluated by immunohistology for binding of the monoclonal antibody 4E, which identifies locus-specific determinants on HLA-B. Some inner cell mass-derived cells (mesenchymal cells) acquired high levels of HLA-B as gestation progressed and other continued to express low levels at late stages of gestation (amnion cells). In contrast, throughout gestation both villous and extravillous trophoblast cells failed to express detectable HLA-B. The binding patterns for 4E followed the patterns established by a monoclonal antibody to class I HLA heavy chains (61D2), and those reported for antisera to allotypic determinants. The findings support the suggestion that trophoblast cells forming the fetal component of the maternal-fetal interface exert highly effective regulation over the expression of class I HLA.

Antibodies, Monoclonal↗

PubMed1989

Cyclic adenosine 3',5'-monophosphate analogues modulate rat placental cell growth and differentiation.

Cyclic adenosine 3',5'-monophosphate (cAMP) has been implicated in the control of placental function. The present investigation was designed to evaluate the actions of cAMP analogues on the control of rat placental development. Two model systems were used to assess the actions of cAMP in the placenta: 1) a rat placental cell line and 2) rat labyrinth placental explants. Elevation of intracellular cAMP via treatment with cAMP analogues, 3-isobutyl-1-methylxanthine, forskolin, or cholera toxin inhibited placental cell DNA synthesis whereas treatment with an analogue to cyclic guanosine 3',5'-monophosphate was without effect. The inhibitory actions of dibutyryl cAMP on DNA synthesis were at least partially reversible and were not the result of metabolic toxicity. Dibutyryl cAMP had dramatic effects on the organization and morphology of placental cells growing in vitro and diminished the ability of the placental cells to grow following transplantation into allogeneic hosts. Differentiation-associated characteristics of rat placental cells were also affected by cAMP. cAMP analogues stimulated placental cell progesterone release and inhibited placental cell alkaline phosphatase activity. Dibutyryl cAMP had effects on placental labyrinth explants similar to its effects on the placental cell line. Dibutyryl cAMP inhibited explant outgrowth while stimulating explant release of progesterone. In summary, cAMP effectively modulates the growth and differentiation of rat placental cells in vitro.

Alkaline Phosphatase↗

PubMed1988

Amnion membrane epithelial cells express class I HLA and contain class I HLA mRNA.

Amnion epithelial cells in membranes from term deliveries, which have been reported not to express histocompatibility Ag, were evaluated for HLA by using an avidin-biotin immunoperoxidase staining system and for class I HLA mRNA by Northern blotting and in situ hybridization. There were three major findings from these studies. 1) Amnion cells frequently expressed class I HLA. Three mAb to monomorphic determinants of class I HLA were used: 61D2, PA2.6, and W6/32. 61D2 identified 1 of 8 fresh amnion membranes as class I positive whereas PA2.6 identified 4/8 and W6/32 identified 5/8. 2) Amnion cells contained class I HLA mRNA. RNA extracted from amnion membranes hybridized to a class I HLA probe (pHLA1.1) in Northern blotting. In situ hybridization procedures with pHLA1.1 showed that essentially all amnion cells contained class I HLA mRNA. 3) Levels of class I HLA mRNA in amnion cells could be modulated. Exposure of amnion explants to medium containing IFN-gamma enhanced levels of class I HLA mRNA in amnion cells, whereas epidermal growth factor diminished those levels. The results suggest that amnion cells transcribe class I HLA genes and are capable of synthesizing class I H chains but that expression may be modulated by extrinsic regulatory molecules.

Amnion↗

PubMed1988

Expression of class I HLA genes by trophoblast cells. Analysis by in situ hybridization.

Evaluation of trophoblast cells by immunohistology has shown that subpopulations of trophoblast cells express class I HLA differently from one another and differently from embryonic and adult cells. Placental syncytial trophoblast does not express detectable levels of class I HLA; chorion membrane cytotrophoblasts bind one mAb to monomorphic determinants of class I Ag, W6/32, but not a second, 61D2. In the present study, sections of normal term placentae and matching extraplacental membranes were evaluated by in situ hybridization procedures for cells containing class I HLA mRNA using pHLA1.1, which is complementary to HLA-B. Class I Ag expression was identified by immunohistology using two mAb to class I HLA (W6/32, 61D2) and the mAb 4E to identify HLA-B. Placental syncytial trophoblast contained low to undetectable levels of class I mRNA and failed to bind all three mAb. Chorion membrane cytotrophoblast cells contained moderate levels of class I HLA mRNA and were positive with the mAb W6/32 but were negative with 61D2 and 4E. In adjacent tissues, fetal mesenchymal cells and maternal decidual cells contained high levels of class I mRNA and were positive with all three mAb. The results suggest that syncytial trophoblast may not express class I HLA because of low steady-state levels of class I HLA mRNA. In contrast, chorionic cytotrophoblast cells may express truncated versions of class I HLA or nonclassical HLA-A,B,C-like Ag. Regulation of the expression of class I HLA gene products may be essential to the development of a satisfactory immunologic relationship between the mother and her semiallogeneic fetus during pregnancy.

Antibodies, Monoclonal↗

PubMed1988

Topographical expression of class I major histocompatibility complex antigens on human amniotic epithelium.

The expression of class I major histocompatibility complex (MHC) antigens on different regions of human amnion was studied by the avidin-biotin-complex immunoperoxidase (ABC) technique using monoclonal antibodies. In contrast to previous reports, the use of higher affinity monoclonal antibodies and the sensitive immunoperoxidase method has allowed the identification of class I MHC antigens on the amniotic epithelium. The level of expression is different between cells from various parts of the amnion, with the amniotic epithelium from the edge of the placenta consistently showing the strongest reactivity. Some of the class I MHC antigens expressed by the amnion are similar to those expressed by extravillous trophoblast cells in that both show much weaker or no reactivity with the monoclonal antibody 61D2.

Amnion↗

PubMed1988

Suppression of postprandial glucose, insulin, C-peptide, and glucose-dependent insulinotropic peptide (GIP) in man by oral administration of a prostaglandin analogue (enprostil).

Enprostil, a long-acting, orally active dehydroprostaglandin E2 with cytoprotective and gastric antisecretory properties, is a potent inhibitor of meal-stimulated gastrin release. Recent data have suggested suppression of additional other gastrointestinal peptide hormones following single doses of enprostil. The current investigation was conducted to further clarify the effects of enprostil administration on gastrointestinal hormones and glucose metabolism under physiologic conditions and to determine whether these effects were present following multiple doses of the agent. Enprostil 70 mcg/d and its placebo were each administered for 7 1/2 days to eight normal male subjects in a study of crossover design, each treatment period lasting 7 1/2 days and separated by a 7 day washout period. Subjects received a test meal on days 1 and 8 and an oral glucose challenge on day 3 of each treatment period following enprostil or its placebo. Following the test meal, there was a delay and suppression of the maximum measured serum glucose levels. Mean overall peak glucose concentrations were lower during the enprostil phase compared to placebo (112 vs. 121 mg/dd, P = 0.025) with a trend toward delay in the time to achievement of peak glucose concentrations. Mean overall peak levels for insulin, C-peptide, and glucose-dependent insulinotropic peptide (GIP) were significantly suppressed by 36%, 16% and 60%, respectively by enprostil when compared to placebo. The overall integrated postprandial responses for insulin, C-peptide, and GIP were significantly reduced by 42%, 39% and 90%, respectively while that for glucose above baseline was reduced by 44% (P = 0.098). Similar effects were present following the oral glucose challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1988

Stimulation of rat placental cell DNA synthesis by transferrin.

The purpose of the present investigation was to evaluate the in vitro requirements for rat placental cell DNA synthesis. A cell line established from the labyrinth region of midgestation rat chorioallantoic placentas was used to examine the actions of various agents. Transferrin was found to stimulate rat placental cell DNA synthesis and cell proliferation. The effects of transferrin on rat placental cell growth paralleled those observed with fetal bovine serum. Rat placental cells were responsive to both rat and human transferrin. Iron-saturated (holo-) transferrin was a more potent stimulator of rat placental cell DNA synthesis than was iron-free (apo-) transferrin. Addition of insulin, epidermal growth factor, or insulin-like growth factor-II to serum-free medium supplemented with rat transferrin did not significantly enhance rat placental cell DNA synthesis beyond that observed with only transferrin. The results demonstrate that a population of cells exists within the rat chorioallantoic placenta that are highly responsive to transferrin.

Animals↗

PubMed1988

Antigen expression by cells near the maternal-fetal interface.

The purpose of the present study was to evaluate the potential for immunologic interaction between the mother and fetus by documenting 1) fetal and maternal cell histocompatibility antigen (HLA) expression and 2) populations of immunologically relevant cells near the maternal-fetal interface through all stages of normal pregnancy. Mesenchymal cells in extraembryonic tissues demonstrated a gradual and progressive development of both class I and class II HLA, with class I expression preceding class II. Coordinated development of expression of two subclasses of class II HLA-D, HLA-DR and HLA-DQ, by fetal mesenchymal cells was noted. In adjacent tissue, maternal decidual cells were strongly class I HLA positive; but in contrast to fetal cells, expression of HLA-D subclasses was discoordinate. HLA-DR was present throughout gestation but HLA-DQ expression was detectable only in second and third trimester tissues. Immunologically relevant cells were present in both fetal and maternal tissues. The major leukocyte population and the major class II-bearing cell type at the maternal-fetal interface was of monocyte/macrophage lineage. T and B lymphocytes were present only in very low densities (1-3% of all cells), whereas at all stages of gestation, macrophages were present in high density in both the fetal mesenchyme (14-25%) and in maternal decidua (27-32%). Documentation of class I and class II HLA expression and the cell types available to participate in immunologic events at the maternal-fetal interface may assist in understanding the immunologic basis of the maternal-fetal relationship during successful pregnancy.

Antigen-Presenting Cells↗

PubMed1987

Normal trophoblasts resist induction of class I HLA.

Very few types of normal cells fail entirely to express class I human leukocyte antigens (HLA), and many of those cells (sperm, fetal amnion epithelial cells, and fetal trophoblasts) are related to the process of reproduction. Susceptibility of sperm to modulation of class I antigens has not been examined, but it has recently been demonstrated that amnion cells respond to exposure to IFN-gamma with readily detectable levels of class I antigens. In addition, one of two trophoblast cell lines (BeWo) has been shown to exhibit enhanced expression of class I HLA in response to IFN-gamma. Expression by a second trophoblast cell line (Jar) was not inducible. Findings in the present study included demonstration of IFN-gamma-enhanced class I-specific mRNA synthesis in JEG-3 cells, which are derived from BeWo, and failure of synthesis by Jar cells. Those results eliminated trivial explanations for the preceding findings and confirmed the responsiveness of some but not all cells of trophoblast origin to IFN-gamma. When successful modulating conditions for amnion and malignant trophoblast cells were applied to normal tissues, third trimester term chorionic cytotrophoblasts and first trimester villous syncytial and cytotrophoblasts failed to exhibit class I HLA. Neither malignant nor normal trophoblasts expressed class II HLA under any condition of testing. Failure of induction of HLA expression by normal trophoblasts could not be attributed to either loss of viability by tissue explants or failure of modulating reagents to reach the trophoblasts. The results demonstrate that regulation of expression of histocompatibility antigens by major populations of normal trophoblasts and one of two choriocarcinoma cell lines differs markedly from that of other fetal and adult cells. Uncommon regulatory mechanisms may be essential to maintenance of the trophoblast as an immunologically inert barrier between the mother and her antigenically disparate fetus.

Antigens, Neoplasm↗

PubMed1987

Speech event related potentials reflect linguistic content and processing level.

Amplitude changes in the auditory event related response reflect differences in linguistic content and the level of processing of spoken sentences. Thus, the neurophysiology of the cognitive processes underlying speech perception can be evaluated by noninvasive techniques. Semantically correct, semantically incorrect, and grammatically incorrect sentences were processed either semantically or syntactically by 25 subjects while their EEGs were recorded. The amplitude of the P250 component to each word varied with processing level. A slow positive wave appeared after semantically correct sentences regardless of the linguistic processing level. N480 and P780 components were observed following words which made the sentences incorrect.

Adult↗

PubMed1987

Human amnion cells: modulation of expression of specific antigens.

Antigen expression by fetal cells near the mother is of interest because of the possibility that some antigens may stimulate beneficial maternal immune responses or may prevent the development of harmful responses. The recent generation of monoclonal antibodies to amnion and trophoblast antigens together with the finding that class I histocompatibility antigen (HLA) expression by amnion cells can be manipulated provided an opportunity to determine if any relationships exist among expression of HLA, amnion antigens, and trophoblast antigens. The results of the present study demonstrate that: class I HLA and amnion-specific antigens are co-expressed by IFN-gamma-modulated amnion cells, so neither prevents expression of the other; EGF enhances expression of two amnion-specific antigens; amnion cells do not express transferrin receptors, placental alkaline phosphatase, or other antigens normally associated with trophoblasts following exposure to IFN-gamma and/or EGF. The results demonstrate independent modulation of expression of class I HLA, two amnion-specific antigens, and some trophoblast-associated antigens on amnion epithelial cells.

Amnion↗

PubMed1987

Loop-acting diuretics do not bind to Tamm-Horsfall urinary glycoprotein.

1. Binding between the radiolabelled loop-acting diuretics ([14C]frusemide, [14C]ethacrynic acid and [3H]bumetanide) and human Tamm-Horsfall glycoprotein or human serum albumin in vitro was evaluated by equilibrium dialysis. 2. The diuretic action and binding to urinary Tamm-Horsfall glycoprotein of the radiolabelled diuretics in vivo, after intravenous administration, were examined in rabbits. 3. In vitro, all three radiolabelled diuretics bound strongly to human serum albumin, but not to Tamm-Horsfall glycoprotein. 4. Radiolabelled frusemide and bumetanide, but not ethacrynic acid, caused a diuresis in rabbits, but no binding between the drugs and Tamm-Horsfall glycoprotein was seen in vivo. 5. Binding to Tamm-Horsfall glycoprotein does not appear to be an important mechanism in the action of loop diuretics.

Animals↗

PubMed1987

Studies to assess the biological relevance of anti-Tamm-Horsfall protein antibodies detected by direct-binding enzyme-linked immunosorbent assay.

1. A role has been suggested for anti-Tamm-Horsfall protein (THP) antibodies in renal disease based on the results of immunoassays of pathological sera. The putative autoantibodies have not been isolated from such sera nor have definitive inhibition studies of their binding been carried out. We have carried out such studies using rabbit anti-THP antibodies as control reagents. 2. Urinary THP prepared by salt precipitation was used to prepare four immunoabsorbent columns by covalent coupling to CNBr-activated Sepharose 4B. After washing with a variety of dissociating agents to remove any non-covalently bound subunit THP, each column was incubated with normal and immune rabbit serum. Fractions washed and eluted from columns were tested for anti-THP antibodies by enzyme-linked immunosorbent assay (ELISA) and THP antigen by radioimmunoassay, and showed NH4SCN (3 mol/l) and guanidine hydrochloride (GuHCl) (6 mol/l) equivalent and sodium dodecyl sulphate (20 g/l) to be inferior in their capacity to produce immunoabsorbent THP capable of isolating specific antibodies from immune rabbit serum. 3. The column treated with GuHCl (6 mol/l) was used further in attempts to isolate putative anti-THP antibodies from five patients, who had a history of urinary tract infections and whose sera showed strong binding by ELISA. 4. Results from direct and inhibition ELISA experiments on fractions collected after washing and elution with all sera suggested that the putative human anti-THP antibodies were of very low affinity and/or directed against non-subunit THP. 5. The pathological relevance of human anti-THP antibodies measured by ELISA remains to be established.

Adult↗

PubMed1986

A sensitive and specific ELISA using a monoclonal capture antibody for detection of Tamm-Horsfall urinary glycoprotein in serum.

An enzyme-linked immunosorbent assay (ELISA) has been established using Nunc polystyrene immunoplates coated with a monoclonal antibody to human Tamm-Horsfall urinary glycoprotein (THP) to detect and measure THP in human serum. Optimal reaction conditions for both the monoclonal capture antibody and the affinity-purified rabbit anti-human THP second antibody were established to produce standard curves which showed linearity between 20-90 ng/ml with a sensitivity of 2-3 ng/ml. The plate-to-plate standard curve mean coefficient of variation (CV) was 5.9 +/- 2.9% on assays performed on the same day while day to day mean CV was 13.3 +/- 2.4%. The specificity of the ELISA was demonstrated by inhibition of binding after preincubation of both urinary THP standards and serum with monoclonal anti-THP antibody. Sera from 195 blood donors tested by the ELISA had a mean concentration of THP antigenic determinants of 260 +/- 105 ng/ml. Results from three control sera run on all plates used in the survey showed mean CV less than 7.6% while no binding was observed with sera from an anephric patient.

Antibodies, Monoclonal↗

PubMed1986

Partial characterization of uterine cells responsible for suppression of murine maternal anti-fetal immune responses.

Several studies have demonstrated that uterine cells are capable of suppressing in vitro immune responses in a nonspecific manner. Two types of cells have been implicated as responsible for suppression, cells with the features of macrophages and a small lymphocyte-like cell. In the present study the maternal anti-paternal mixed lymphocyte reaction was used to investigate further the characteristics of uterine suppressor cells. Three distinct suppressor cell populations were identified: highly suppressive macrophages, small lymphocyte-like cells, and a morphologically heterogeneous third population of highly suppressive cells. The data from this study suggest that pregnant murine uteri contain a variety of cells capable of discouraging lymphocyte proliferation in vitro.

Animals↗

PubMed1986

Implication of prostaglandin E2 in soluble factor-mediated immune suppression by murine decidual cells.

Cells from the uteri of pregnant mice mediate profound nonantigen-specific and nonmajor histocompatibility complex-restricted immune suppression in vitro. In part, those cells accomplish suppression by releasing soluble suppressor factors. The purpose of the present study was to initiate identification of uterine cell suppressor factors. Immune suppression was assayed by the effect of decidual cells or in vitro generated supernatants of decidual cells on mixed lymphocyte reactions (MLR). The following findings support the designation of prostaglandin E2 (PGE2) as a primary suppressor molecule originating with decidual cells: Suppression mediated by supernatants of decidual cells was relieved by removal of lipids but not proteins; indomethacin, an inhibitor of prostaglandin synthesis, produced partial relief of suppression mediated by uterine cells and totally inhibited soluble suppressor factor generation by those cells; decidual cells produced high levels of both PGE2 and PGF2a; the addition of exogenous PGE2 at levels comparable to those found in the decidual cell supernatants restored suppression by decidual cells and their supernatants whereas the addition of PGF2a had no effect; inhibition of the lipoxygenase pathway of arachidonate metabolism had no effect on cell or supernatant mediated suppression; nonspecific suppressor mechanisms, such as arginine depletion and peroxide generation, were excluded as possible mediators of MLR suppression by decidual cells and their supernatants. Fractionation of decidual cells revealed at least three indomethacin-sensitive cell types: small, lymphocyte-like cells, macrophages, and a third population of large decidual cells that was not identified by specific markers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Interferon-gamma induces class I HLA and beta 2-microglobulin expression by human amnion cells.

In contrast to other human nucleated cells, amnionic epithelial cells do not normally express class I HLA antigens. It is not known whether the failure of display of those antigens occurs because genes for HLA expression are deleted or are defective, or if gene expression is repressed. The results of the present study demonstrate that amnionic epithelial cells exposed to IFN-gamma express levels of class I HLA antigens and beta 2-microglobulin that are readily detectable in immunoperoxidase and immunofluorescence stains. The findings suggest that failure of transcription may be responsible for failure of normal expression of class I HLA antigens and beta 2-microglobulin by cells of the amnion membrane. Class II antigens, which are normally expressed by very few cell types, were not expressed by amnion cells under any test conditions.

Amnion↗

PubMed1986

Relationship of abnormal Tamm-Horsfall glycoprotein localization to renal morphology and function.

Tamm-Horsfall glycoprotein (TH) distribution was studied using a biotin-avidin immunoperoxidase technique in renal biopsies from 166 consecutive patients and 8 normal kidneys. Tubulointerstitial damage was independently assessed and graded. In 109 patients TH antibodies were measured by ELISA and in 30 of these urinary TH and beta 2-microglobulin excretions were measured by radioimmunoassay. In 124 biopsies only distal tubular epithelium and casts were stained. Glomerular space (8) or interstitial (34) deposits were seen in 42 biopsies; 16/68 with glomerulonephritis, 4/14 with systemic vasculitis, 12/33 with chronic interstitial nephritis, 1/8 with acute interstitial nephritis, 9/43 with other nephropathies. There was no correlation between TH distribution and the degree of tubulointerstitial damage (p greater than 0.5), urinary TH excretion (p greater than 0.05), urinary beta 2-microglobulin excretion (p greater than 0.05), glomerular filtration rate, urinary concentrating ability, or the incidence of pyuria. TH antibodies did not correlate with TH distribution (p greater than 0.5) or the degree of tubulointerstitial damage. Abnormal TH distribution showed no statistical relationship to the degree of tubulointerstitial damage, changes in renal function or levels of TH antibodies.

Animals↗