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Biomedical subjects

D J Anderson

Publications and source records attributed to D J Anderson.

At least 217 records · Page 12Linked to original sources
PubMed1994

Inhibition of the biotransformation and pharmacological actions of glyceryl trinitrate by the flavoprotein inhibitor, diphenyleneiodonium sulfate.

Recent studies suggest a role for the vascular cytochrome P450-NADPH cytochrome P450 reductase system in mediating the biotransformation of glyceryl trinitrate (GTN) to nitric oxide (or some closely related species), resulting in increased cyclic GMP accumulation and vasodilation. In this study we tested the effect of the flavoprotein inhibitor, diphenyleneiodonium sulfate (DPI) on GTN action in isolated rat aorta. Exposure of phenylephrine-contracted tissues to DPI (10 nM-0.3 microM) resulted in 3- to 10-fold increases in the EC50 values for GTN-induced relaxation in both endothelium-intact tissues and endothelium-denuded tissues, whereas the vasodilator response to sodium nitroprusside was unaffected. Consistent with the relaxation data, cyclic GMP accumulation induced by 0.3 or 2 microM GTN was inhibited by 0.3 microM DPI in both endothelium-intact and endothelium-denuded aortic strips, whereas cyclic GMP accumulation induced by 0.1 microM sodium nitroprusside was unaffected. The regioselective formation of glyceryl-1,2-dinitrate observed during the aortic biotransformation of GTN was inhibited markedly by DPI. In tissues incubated with 0.3 or 10 microM DPI for 30 min followed by washout for 60 min, the EC50 values for GTN-induced relaxation were increased 2-fold, and both GTN-induced cyclic GMP accumulation and vascular GTN biotransformation were decreased. This suggests an irreversible component to the inhibitory action of DPI. Together, these data provide evidence for the involvement of a flavoprotein (e.g., NADPH cytochrome P450 reductase) in the metabolic activation of GTN required for expression of its vasodilator activity.

Animals↗
PubMed1994

Modulation of human granulosa cell steroid production in vitro by tumor necrosis factor alpha: implications of white blood cells in culture.

OBJECTIVE: To test the hypothesis that the macrophage cytokine, tumor necrosis factor-alpha (TNF-alpha), directly inhibits progesterone, estrone (E1), and estradiol (E2) synthesis by human granulosa cells in vitro in the presence and absence of white blood cells. METHODS: Granulosa cells from follicle aspirates of patients undergoing in vitro fertilization (IVF) were separated from red blood cells on 50% Percoll columns. Such preparations contained numerous white blood cells (lymphocytes, 40-52%, and macrophages, 6-14%) as determined with immunocytochemistry. In some studies, anti-CD45 magnetic beads followed by an additional adherence step and media change were used to remove white blood cells from granulosa cell cultures. Granulosa cells with and without associated white blood cells were cultured in basal and hCG-supplemented media. Androstenedione (40 ng/mL) and/or recombinant TNF-alpha (0.5-50 ng/mL) were added to triplicate wells. Media were harvested for radioimmunoassay of progesterone, E1, and E2 after 24 and 48 hours of incubation. RESULTS: The effects of TNF-alpha on progesterone production in white blood cell-associated cultures were inconsistent when 0.5 ng/mL TNF-alpha was added under basal conditions. At higher TNF-alpha doses (5-50 ng/mL) and under hCG-stimulated conditions, there was a consistent decrease in progesterone production, but the effect was not clearly dose-dependent. It was possible to remove white blood cells effectively from granulosa cell cultures. In granulosa cell cultures without associated white blood cells, 0.5 ng/mL of TNF-alpha at 48 hours produced an increase in progesterone, whereas 50 ng/mL of TNF-alpha decreased progesterone (P < .001). Estrone and E2 were both decreased by TNF-alpha regardless of whether white blood cells were present in culture, without clear evidence of dose-dependency. Granulosa cell viability and proliferation were unaffected by TNF-alpha as demonstrated by direct cell counts, trypan blue exclusion, and tetrazolium salt viability assays. CONCLUSIONS: In the normal ovary, TNF-alpha may influence the development of the dominant follicle by inhibiting aromatase activity. It may also mediate oocyte maturation disorders and ovarian endocrine dysfunction in some pathologic states. White blood cells can be effectively removed from granulosa cell cultures. Application of this removal technique will facilitate future granulosa cell studies by allowing more precise determination of direct granulosa cell function.

Androstenedione↗
PubMed1994

Effects of cytokines on epidermal growth factor receptor expression by malignant trophoblast cells in vitro.

Trophoblastic cells abundantly express epidermal growth factor (EGF) receptors, which, when activated by EGF or transforming growth factor-alpha, can influence cellular growth and metabolism. Various lymphocyte and macrophage cytokines have been found to influence the proliferation of human choriocarcinoma (CCA) cells in vitro. In the current study we investigated the possibility that certain cytokine effects are mediated by changes in EGF receptor expression. JEG-3 human CCA cells were incubated with varying concentrations of interleukin 1-alpha (IL-1 alpha), interleukin 1-beta (IL-1 beta), interleukin 2, gamma-interferon, granulocyte-macrophage colony stimulating factor and tumor necrosis factor-alpha (TNF), and the expression of EGF receptor was measured by radioimmunoassay using a murine monoclonal antibody with specificity for the EGF receptor. Proliferative or growth suppressive effects of the cytokines were assessed by quantitative analysis of the DNA in the cell culture wells. Macrophage-derived cytokines IL-1 alpha, IL-1 beta and TNF significantly suppressed cell growth; this was associated with a significant increase in EGF receptor expression. The other cytokines had no significant effect on either EGF receptor expression or cell growth. We also studied the expression of EGF mRNA in JEG-3, Jar and BeWo CCA cell lines. By reverse transcription followed by polymerase chain reaction, low levels of EGF mRNA were detected in all three cell lines. Therefore, EGF may be synthesized by JEG-3, Jar and BeWo CCA cell lines to participate in an autocrine growth pathway. Our findings support the concept that cytokines may act as paracrine mediators of autocrine processes involved in CCA cell growth regulation by modulating growth factor receptor expression.

Blotting, Northern↗
PubMed1993

Mammalian achaete-scute homolog 1 is required for the early development of olfactory and autonomic neurons.

The mouse Mash-1 gene, like its Drosophila homologs of the achaete-scute complex (AS-C), encodes a transcription factor expressed in neural precursors. We created a null allele of this gene by homologous recombination in embryonic stem cells. Mice homozygous for the mutation die at birth with apparent breathing and feeding defects. The brain and spinal cord of the mutants appear normal, but their olfactory epithelium and sympathetic, parasympathetic, and enteric ganglia are severely affected. In the olfactory epithelium, neuronal progenitors die at an early stage, whereas the nonneuronal supporting cells are present. In sympathetic ganglia, the mutation arrests the development of neuronal precursors, preventing the generation of sympathetic neurons, but does not affect glial precursor cells. These observations suggest that Mash-1, like its Drosophila homologs of the AS-C, controls a basic operation in development of neuronal progenitors in distinct neural lineages.

Adrenal Medulla↗
PubMed1993

The role of complement component C3b and its receptors in sperm-oocyte interaction.

Previous studies have shown that human sperm that have undergone the acrosome reaction express a unique tissue-specific variant of the complement component 3 (C3)-binding molecule membrane cofactor protein (MCP, CD46) and that damaged or dead sperm activate the alternative pathway of complement and bind C3 catabolites. In this study we provide evidence that MCP on sperm that have undergone the acrosome reaction specifically binds dimeric C3b and that human sperm acrosomal proteases released during the acrosome reaction directly cleave C3, facilitating its binding to MCP. Furthermore, human and hamster oocytes can activate the alternative pathway of complement and also bind human C3 fragments. Monoclonal antibodies specific for complement receptors type 1 (CD35) and type 3 (CD11b/CD18) bind to the human oocyte plasma membrane, indicating that specific complement-binding molecules may play a role in the attachment of C3 catabolites to oocytes. Subsaturating concentrations of dimeric C3b (0.01-1 microM) promoted penetration of hamster oocytes by human sperm, whereas saturating doses (> 10 microM) inhibited this process. In addition, antibodies to both MCP and C3 significantly inhibited penetration of hamster oocytes by human sperm. These data provide evidence that regulated gamete-induced generation of C3 fragments and the binding of these fragments by selectively expressed receptors on sperm and oocytes may be an initial step in gamete interaction, leading to membrane fusion and fertilization.

Adult↗
PubMed1993

Cytokines and growth factors in implantation.

A variety of cell types at the blastocyst implantation site produce cytokines and growth factors that could play an important role in the implantation process. Furthermore, receptors for cytokines and growth factors have been detected on embryonic and trophoblastic cells. The purpose of the article is to review the published literature on the effect of cytokines and growth factors on implantation events, and to present recent data from our laboratory on effects of growth factors and cytokines on mouse blastocyst implantation events in vitro.

Animals↗
PubMed1993

Determination of fibrinogen in plasma by high-performance immunoaffinity chromatography.

A high-performance immunoaffinity chromatographic (HPIAC) method for fibrinogen was developed which had several advantages over existing methodologies including increased linear range and no interference from heparin. Several modifications of usual HPIAC procedures were necessary including the employment of a methacrylate polymeric support to reduce non-specific adsorption and the addition of urea to a pH 2.1 elution buffer to affect elution. A significant split-peak effect (i.e., unretained fibrinogen) was noted at higher flow-rates and at higher fibrinogen concentrations, which was shown to be temperature-dependent, with the amount of fibrinogen retained on the column increasing with increased temperature.

Antibodies↗
PubMed1993

Cell fate determination in the peripheral nervous system: the sympathoadrenal progenitor.

Studies of postnatal chromaffin cells, sympathetic neurons and Small Intensely Fluorescent (SIF) cells have suggested that these cells develop from a common progenitor, the sympathoadrenal (SA) progenitor, whose fate is determined by the relative levels of nerve growth factor (NGF) and glucocorticoid (GC) in its environment (Unsicker et al., 1978, Proc. Natl. Acad. Sci. USA 75:3498-3502; Doupe et al., 1985a, J. Neurosci. 5:2119-2142). Recent studies have identified such a bipotential SA progenitor in the rat embryo. Surprisingly, this progenitor is initially unresponsive to NGF; neuronal differentiation is instead promoted by fibroblast growth factor (FGF). However, FGF appears to promote NGF responsiveness, suggesting that neuronal differentiation involves a relay or cascade of growth factor action. Furthermore, chromaffin cell differentiation appears to involve two sequential, GC-dependent events: the inhibition of neuronal differentiation and the induction of epinephrine synthesis. The former event is a prerequisite to the latter. Thus both the chromaffin and neuronal pathways of differentiation follow a series of dependent events, involving changes in the responsiveness of SA progenitors to environmental factors. Such changes correlate with changes in antigenic marker expression that can be observed in vivo. In addition to choosing between neuronal and endocrine fates, SA progenitors must also express an appropriate neurotransmitter phenotype. For example, sympathetic neurons can become either noradrenergic or cholinergic. This cholinergic potential is already present in uncommitted SA progenitors, as evidenced by their ability to synthesize acetylcholine. Recent studies suggest that these cells may have yet other developmental capacities, including the ability to synthesize serotonin. This capacity is consistent with the hypothesis that SA progenitors are closely related to progenitors of enteric neurons, an idea supported by recent observations using novel antigenic markers. The SA progenitor may be, therefore, a "master" neuroendocrine progenitor for the peripheral nervous system.

Adrenal Medulla↗
PubMed1993

Lineage diversification of the neural crest: in vitro investigations.

This review addresses the contribution of in vitro investigations to our understanding of neural crest development. Cell culture has been used to study the environmental control of cell lineage decisions in the neural crest and to define the developmental potentials of specific populations of neural crest and neural crest-derived cells. We consider the roles of environmental signals in the context of the development of several different neural crest-derived lineages. We also discuss evidence for influences of local cell-cell interactions and substrate molecules on neural crest development. Data bearing on the issues of neural crest cell multipotency, self-renewal, and lineage commitment are reviewed.

Animals↗
PubMed1993

Molecular diversity of the SCG10/stathmin gene family in the mouse.

SCG10 is a neuronal growth-associated protein that shares an amino acid sequence similarity with an 18- to 19-kDa phosphoprotein named stathmin (also called p19, p18, Op18, pp17, prosolin, pp20, 19K, and leukemia-associated phosphoprotein, Lap18), which is more broadly expressed in a variety of cell types of the neural, immune, and reproductive systems. The sequence similarity has suggested that SCG10 and stathmin have been derived from structurally and evolutionarily related genes. To explore the structural and evolutionary relationships between these genes, we have isolated a series of cosmid and phage clones that covers the entire region of the mouse stathmin gene and most of the mouse SCG10 gene. The SCG10 transcription unit spans at least 30 kb, while the stathmin gene is 6 kb in length. Both genes consist of five exons, and many of the intron/exon boundaries fall into the homologous regions of conserved domains of these two proteins. However, the promoter-proximal regions are distinct in the two genes, suggesting that they have evolved by fusion of the duplicated coding exons to unique promoters. Southern blot analysis indicates that SCG10 mRNA is encoded by a single gene in the mouse genome, while stathmin cDNA probes detect multiple genes. Chromosome mapping experiments reveal that the SCG10 gene is localized at the proximal region of mouse chromosome 3 and is linked to Il-7, while the stathmin gene loci are distributed to three chromosomes; the authentic stathmin gene lies on chromosome 4, whereas the loci on chromosomes 9 and 17 are likely to be pseudogenes. These data are consistent with the idea that the neuron-specific SCG10 gene evolved by duplication and modification of the more broadly expressed stathmin/Lap18 gene.

Amino Acid Sequence↗
PubMed1993

Cell and molecular biology of neural crest cell lineage diversification.

Neural crest cells are multipotent progenitor cells, but it is not understood how these cells generate their diverse differentiated progeny. This review considers the issues of whether neural crest cells self-renew, whether they generate partially committed intermediate progenitors, and how the local embryonic environment may act to control this diversification process. Novel molecular markers for neural crest cells are also discussed.

Animals↗
PubMed1993

Comparison of methods to enumerate white blood cells in semen.

Seminal WBC counts obtained by an mAb-based immunohistologic method correlated well with seminal granulocyte counts obtained with a simple peroxidase method (rho = +0.70; P < 0.0001). However, total WBC counts were significantly higher than granulocyte counts for most samples. With the immunohistologic method, 17 of 112 samples (15.2%) contained > 10(6) WBC/mL semen, whereas the peroxidase method resulted in only 10 samples (8.9%) with > 10(6) WBC/mL. When the threshold defining leukocytospermia was set at 1 x 10(6) positive cells/mL for both methods, the specificity of the peroxidase test compared with the immunohistology technique was 100% (10/10), but the sensitivity was only 58.8% (10/17). When the threshold for leukocytospermia in the peroxidase test was lowered to 5 x 10(5) positive cells/mL semen, the sensitivity relative to the immunohistology technique increased to 94.1% (16/17), and specificity remained 100% (16/16). Likewise, good interassay sensitivity and specificity values were obtained with thresholds of 10(6) WBC/mL for the peroxidase assay and 2 x 10(6) WBC/mL for the immunohistology assay. We conclude that either peroxidase or immunohistology assays can be used to screen for leukocytospermia, but that more research is needed to establish thresholds for pathological levels of WBC in semen using these two approaches. Total round cell counts are of no value for enumerating WBC in semen.

Analysis of Variance↗
PubMed1993

Effects of growth factors and growth factor-extracellular matrix interactions on mouse trophoblast outgrowth in vitro.

A variety of cell types at the blastocyst implantation site produce growth factors that could play important role(s) in the implantation process. Recent evidence indicates that decidual cells and/or embryos produce transforming growth factor-alpha (TGF-alpha), epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), and colony-stimulating factor (CSF-1). Furthermore, receptors for EGF, PDGF, and CSF-1 have been detected on embryonic and trophoblastic cells. The purpose of this study was to investigate the effects of these growth factors and possibly growth factor-extracellular matrix interactions on mouse blastocyst attachment and trophoblast outgrowth in vitro. Various dilutions of the growth factors TGF-alpha, EGF, PDGF, FGF, and CSF-1 were added to cultures of 5-day-old hatched blastocysts in fibronectin-coated plastic wells. Blastocysts were scored for attachment, trophoblast outgrowth, and surface area at 24, 48, and 72 h. Each of these growth factors significantly enhanced trophoblast outgrowth, and a cocktail containing all of the growth factors had a significantly stronger effect. PDGF and FGF, but no other growth factors, also enhanced trophoblast outgrowth following pulsatile incubation with the fibronectin matrix coating of the culture wells, indicating that interactions between these growth factors and extracellular matrix elements could influence implantation. This study suggests that various growth factors may play an important role in the implantation process, that synergistic effects may be obtained by combinations of growth factors, and that interactions between certain growth factors and extracellular matrix elements may be significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Environmental factors related to the outcome of panic disorder. A seven-year follow-up study.

The purpose of this study was to examine factors related to the outcome of naturalistically treated panic disorder. In order to achieve this we followed up 69 patients 7 years after they had presented at a psychiatric clinic. At follow-up, the patients were generally doing well despite persisting symptoms. Patients who were more severely ill at the time of initial assessment had a worse outcome. These patients had more severe panic and agoraphobic symptoms, had illnesses of longer duration, and more often had histories of major depression. Among the developmental variables examined, separation from a parent by death or divorce was strongly related to poor outcome. Other factors associated with poor outcome included high interpersonal sensitivity, low social class, and unmarried marital status. The findings show that, for this chronic illness, measures of severity and chronicity predict more severe and persisting symptoms. They also indicate that outcome is importantly related to the social environment in which the illness develops and with which it interacts.

Adult↗
PubMed1993

Molecular control of cell fate in the neural crest: the sympathoadrenal lineage.

Over the past five years, new insights have been gained into the biology of the SA lineage. These advances have been powered by the development of immunologic methods to isolate embryonic SA progenitors from fetal adrenal glands and sympathetic ganglia. Analysis of these embryonic progenitors has confirmed many of the ideas derived from earlier studies of postnatal cells, but has necessitated several revisions in our thinking, as well. First, embryonic SA progenitors appear to be distinct from mature SIF cells, a cell type initially postulated to be the central intermediate in the SA lineage. Second, FGF, not NGF, appears to be an important early influence on neuronal fate; NGF responsiveness appears relatively late in differentiation. Third, the development of both sympathetic neurons and adrenal chromaffin cells is not a one-step process, but rather involves a series of events, in which the cells change their responsiveness to growth factors and glucocorticoids. Fourth, emerging circumstantial evidence suggests that SA progenitors may have additional developmental potentials. Finally, new insights have been gained into the molecular mechanisms that underlie both the differentiation of SA progenitors and their determination from earlier multipotent neural crest cells. These advances have made the SA progenitor a well-defined system for studying the molecular control of cell fate in a vertebrate neurogenic precursor cell. The analysis of the SA lineage at the cell biological level has raised several interesting molecular questions for future investigation. In the neuronal branch of the SA lineage, how is the acquisition of NGF-responsiveness and NGF-dependence controlled, and what is the relationship of these events to the expression of p140trk and p75? In the chromaffin branch of the pathway, which molecules control the timing of PNMT expression? In the uncommitted SA progenitor, what is the molecular basis of the antagonism between the competing neuronal and chromaffin pathways of differentiation, and how does commitment to neuronal differentiation occur? Can SA progenitors differentiate to enteric neurons in vitro, and which differentiation and survival factors control this phenotype, as well as the other classical neurotransmitter and neuropeptide phenotypes expressed by SA derivatives? What are the roles of MASH1 and other regulatory genes in controlling early stages in neural crest cell determination, and how is the expression of these molecules in turn controlled? How much of the genetic regulatory network controlling neuronal differentiation in Drosophila has been conserved in vertebrates?(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Medulla↗
PubMed1993

Pediatric lung transplantation: radiographic-histopathologic correlation.

Chest radiographic and histopathologic findings were retrospectively reviewed to determine the spectrum of findings in 16 children who underwent a total of 19 lung transplantations. Radiographs were evaluated for air-space disease, interstitial disease, Kerley B lines, pleural fluid, and cardiac size, and the interval from transplantation to the onset of complications was determined. Radiographic findings were correlated with 62 histopathologic diagnoses obtained from 51 transbronchial and open lung biopsy specimens. The final histopathologic diagnoses were acute rejection (n = 19), chronic rejection (n = 8), infection (n = 11), lymphoproliferative disorder (n = 4), and nonspecific (n = 20). The radiographic patterns of the complications were not significantly different. Seventy-nine percent (15 of 19) of episodes of acute rejection and 64% (seven of 11) of episodes of infection occurred within 5 weeks of transplantation, while 63% (five of eight) of the episodes of chronic rejection occurred after this period. Since chest radiographs are nonspecific, caution should be exercised in basing clinical decisions only on the radiographic pattern in the absence of corroborative clinical and histopathologic findings.

Adolescent↗
PubMed1993

XASH-3, a novel Xenopus achaete-scute homolog, provides an early marker of planar neural induction and position along the mediolateral axis of the neural plate.

We have isolated a novel Xenopus homolog of the Drosophila achaete-scute genes, called XASH-3. XASH-3 expression is neural specific and is detected as early as stage 11 1/2, making it one of the earliest markers of neural induction so far described. Moreover, XASH-3 expression within the neural plate is regionally restricted. Transverse bands of XASH-3 mRNA mark discrete positions along the anteroposterior axis, while longitudinal bands mark a discrete position along the mediolateral axis. This latter site of XASH-3 expression appears to demarcate the prospective sulcus limitans, a boundary zone that later separates the functionally distinct dorsal (alar) and ventral (basal) regions of the spinal cord. In sandwich explants lacking any underlying mesoderm, XASH-3 is expressed in longitudinal stripes located lateral to the midline. This provides the first indication that planar or midline-derived inductive signals are sufficient to establish at least some aspects of positional identity along the mediolateral axis of the neural plate. By contrast, the transverse stripes of XASH-3 expression are not detected, suggesting that this aspect of anteroposterior neural pattern is lost or delayed in the absence of vertically passed signals. The restricted mediolateral expression of XASH-3 suggests that mediolateral patterning of the neural plate is an early event, and that this regionalization can be achieved in the absence of inducing signals derived from underlying mesoderm.

Animals↗