Search PubMed⌕ Search

Biomedical subjects

M L Richards

Publications and source records attributed to M L Richards.

At least 37 records · Page 2Linked to original sources
PubMed1990

The binding of IgE to murine Fc epsilon RII is calcium-dependent but not inhibited by carbohydrate.

Despite extensive study, little is known about the functions of the moderate affinity IgE receptors (Fc epsilon RII) on B cells. Recent cDNA and genomic cloning studies have demonstrated that, in contrast to other FcR, Fc epsilon RII is not a member of the Ig gene superfamily. Moreover, it uniquely expresses a region that is highly homologous with a membrane-associated, calcium-dependent binding lectin, the asialoglycoprotein receptor. We now report that the interaction between IgE and the Fc epsilon RII of murine B cells and macrophages requires calcium. Furthermore, as might be expected of asialoglycoprotein lectins, this binding was pH-dependent and resulted in ligand internalization. However, although 125I-Fc epsilon RII bound in a calcium-dependent manner to monosaccharide-agarose beads, high concentrations of mono- and disaccharides did not inhibit the interaction between either 125I-IgE and intact B cells or 125I-Fc epsilon RII (from surface-labeled B cells) and IgE-Sepharose. These results suggest that although murine Fc epsilon RII is a lectin, it is not strictly dependent upon IgE oligosaccharides for its binding to IgE.

Animals↗
PubMed1990

The induction of murine B cell Ia by IgE-antigen complexes is dependent on protein synthesis and preceded by class II mRNA accumulation.

Complexes of murine monoclonal anti-DNP IgE and DNP-OVA interact with murine B cells to stimulate expression of cell surface Ia antigens. Enhanced membrane expression of class II MHC antigens was accompanied by a threefold increase of I-A and I-E transcripts, as measured by Northern blot. Peak accumulation of Ia mRNA were detected after 6 hr of incubation with IgE-antigen complexes and returned to control levels after 12 hr of incubation. Hence, induction of Ia mRNA by IgE-antigen complexes was compatible with cell surface Ia expression, both quantitatively and with regard to the time frame. The Ia-inductive effects of both IL-4 and IgE-antigen complexes were inhibited by cycloheximide and actinomycin-D. However, whereas actinomycin-D and cycloheximide blocked IL-4 induction of Fc epsilon RII expression, inhibition of transcription or protein synthesis did not abrogate the increased expression of Fc epsilon R associated with IgE-antigen complexes. These results suggest that the IgE-antigen-induction of B cell Ia expression follows from activation of transcription and de novo synthesis of Ia antigens.

Animals↗
PubMed1989

Perioperative nursing research. Part VI: Postoperative phase.

The universe of knowledge applicable to the nursing care of patients during the postoperative phase is quite diverse. Interpretation of clinical studies requires caution when confounding variables are not controlled. The variety of articles applicable to postoperative nursing care clearly demonstrates the need for nurses to have advanced knowledge in science, particularly physiology, to fully grasp the phenomena occurring in the postoperative patient. Nurse investigators are commended for their research efforts and are encouraged to continue challenging intuitive and traditional clinical nursing practices.

Blood Circulation↗
PubMed1988

IgE-antigen complexes enhance Fc epsilon R and Ia expression by murine B lymphocytes.

Murine monoclonal IgE interacts with B cells of BALB/c mouse spleen with greater efficiency in the presence of its specific antigen. Complexes of anti-DNP IgE and DNP-OVA not only resist elution from B lymphocytes by acid but have a substantially longer dissociation half-time when compared with monomeric IgE (440 vs. 8 min, respectively). Further, these IgE-antigen complexes induce Fc epsilon R expression in lymphoid cells more efficiently than IgE alone. Maximum levels of B cell Fc epsilon R were observed after a 24 h incubation with 1 microgram/ml IgE in the presence of 1 microgram/ml DNP-OVA, while 30 micrograms/ml monomeric IgE was needed to elicit a similar increase of Fc epsilon R expression. Most importantly, overnight incubation of B cell-enriched BALB/c spleen cells with IgE-antigen complexes resulted in an augmented membrane expression of class II MHC antigens. B cell surface expression of both I-A and I-E antigens responded to a comparable level after incubation with IgE-antigen complexes but did not occur in response to either IgE or antigen alone. The enhanced sIa expression occurred in parallel to IgE-antigen concentrations that gave rise to Fc epsilon R hyperexpression. Moreover, double staining for Fc epsilon R and surface Ia antigen shows that B cells exhibiting the highest density of Fc epsilon R also demonstrated the most surface I-A, suggesting that B lymphocytes are autonomous in their response to IgE-antigen complexes. Changes in class I MHC or sIgM were not observed after overnight incubation with IgE and antigen. These results demonstrate the importance of IgE-antigen complexes for intercellular signaling and further suggest that the IgE system plays a broader role in immune response than it has generally been credited.

Animals↗
PubMed1988

Differentiation of human neuroblastoma cells: marked potentiation of prostaglandin E-stimulated accumulation of cyclic AMP by retinoic acid.

Neuroblastoma cells in culture contain low levels of cyclic AMP, a second messenger which plays a major role in neuronal maturation. In this study, human neuroblastoma cells, SK-N-SH-SY5Y, were induced to differentiate by treatment with either nerve growth factor (50 ng/ml), retinoic acid (10 microM), dibutyryl cyclic AMP (1 mM), or 12-O-tetradecanoylphorbol-13-acetate (0.1 microM), and the ability of several neurotransmitters or hormones to stimulate adenylyl cyclase was tested. Although all four differentiation factors caused morphological changes towards a neuronal phenotype, only retinoic acid dramatically enhanced cyclic AMP accumulation, specifically upon stimulation with prostaglandin E1 (PGE1). PGE2 was also active, but less potent, than PGE1, whereas the other cyclic AMP-stimulating agents tested were largely unaffected. Further, the rapid desensitization of the PGE1-cyclic AMP response observed in control cells after 20 min of PGE1 exposure did not occur in retinoic acid-treated cells, and the EC50 values for PGE1 were reduced from approximately 240 to 14 nM after retinoic acid treatment. The increased sensitivity to PGE was associated with an increase of high-affinity PGE1 binding sites, whereas the Gs coupling proteins and adenylyl cyclase were not measurably affected. A similar enhancement of the PGE1-cyclic AMP response by retinoic acid was also observed in two additional human neuroblastoma cell lines tested, Kelly and IMR-32, suggesting that up-regulation of the prostaglandin response by retinoic acid is common among neuroblastoma cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1987

Expression of neurotransmitter receptors and myc protooncogenes in subclones of a human neuroblastoma cell line.

Phenotypic variability of the human neuroblastoma cell line SK-N-SH was studied with the use of three subclones that interconvert at a slower rate than the parent cell line, i.e., a neuroblast-type subclone (SH-SY5Y), a nonneuronal, strongly substrate adherent subclone (SH-EP), and an intermediate type subclone (SH-IN). Rhodamine-phalloidin staining of actin fibers revealed differences in the cytoskeleton morphology of the three subclones, while the clathrin subunit proteins (heavy and light chains), components of coated vesicles, were invariant. Dramatic differences were observed for the expression of neurotransmitter systems, i.e., the mu and delta opioid receptor, the muscarinic cholinergic receptor and its effect on phosphatidylinositol turnover, and the uptake1 transporter for catecholamines. While these systems were strongly expressed in the parent line and the neuroblast-like clones SH-SY5Y and SH-IN, they were absent or barely detectable in the nonneuronal EP clone. Furthermore, the protooncogenes N- and c-myc were only expressed in the neuroblast containing lines, consistent with their growth characteristics of fully transformed cells. The strong c-myc expression in the absence of c- or N-myc amplification in SK-N-SH, adds a new form of high protooncogene activity in neuroblastoma cell lines. The remarkable differences of neurotransmitter systems and myc expression among the various phenotypes of human neuroblastoma cells should be considered in the therapy of neuroblastoma.

Actins↗
PubMed1986

Human neuroblastoma cell lines as models of catechol uptake.

This report compares the effect of antidepressants on the accumulation of [3H]catecholamines in two human neuroblastoma cell lines, IMR-32 and SK-N-SH, and a rat pheochromocytoma cell line, PC-12. Analysis of the catecholamine uptake system in SK-N-SH cells revealed that both [3H]dopamine and [3H]norepinephrine accumulated via a single competitive, saturable and apparently active process. Similar potencies exhibited by several inhibitors suggest that identical uptake systems exist in all 3 cell lines, with SK-N-SH cells being the most active. Although SK-N-SH and PC-12 cells have been reported to secrete dopamine in preference to other catecholamines, high intracellular concentrations of [3H]norepinephrine were measurable after incubation with [3H]dopamine. Additionally, [3H]norepinephrine/[3H]dopamine ratios increased with longer tracer incubations, in the presence of exogenous ascorbate and when including O-methylated metabolites. Moreover, accumulation of [3H]catechols was competitively inhibited by various antidepressants, with maximal inhibition to 7% of control and Kis consistent with reported noradrenergic uptake transport systems. Hence, the human neuroblastoma cell lines studied appear to serve as appropriate models of catechol reuptake processes in noradrenergic cells.

Animals↗
PubMed1986

In vivo binding of putative delta-selective opioid antagonists to central opiate receptors.

The in vivo opiate receptor binding of three putative delta-selective opioid antagonists, the irreversible oripavine ligand NIH 10236 and two enkephalin analogs, ICI 154,129 and ICI 174,866, was studied in rat brain. Following i.c.v. injection, potent and apparently irreversible opiate receptor binding was observed for NIH 10236 with similar affinity for mu, delta and kappa sites. However, opiate receptor binding was not evident either after s.c. injection of NIH 10236 or ICI 154,129, or following i.c.v. administration of ICI 154,129 or ICI 174,864. The receptor sites that mediate the pharmacological effects of these drugs should be reevaluated.

Animals↗
PubMed1986

A human neuroblastoma cell line expresses mu and delta opioid receptor sites.

A series of neuroblastoma cell lines were screened for the presence of opioid receptor sites with the tracers [3H]diprenorphine (mu, delta, kappa ligand) and [3H]naloxone (mu-selective ligand). One human neuroblastoma cell line, SK-N-SH, displayed avid binding for both tracers. Binding experiments with multiple tracers revealed the presence of both mu and delta sites. These sites were stereospecific, saturable, and proteinaceous in character. Saturation binding experiments provided an estimate of 50,000 mu and 10,000 delta sites/cell. NaCl (100 mM) and guanine nucleotide, guanylyl imidodiphosphate (50 microM), reduced opioid agonist but not antagonist binding to these sites. Etorphine at 1 nM inhibited prostaglandin E1-stimulated cyclic AMP production by approximately 20%, which was reversible by naloxone. The opioid-binding sites on SK-N-SH cells closely resemble the previously reported mu and delta sites in human and rodent brain. Therefore, the SK-N-SH neuroblastoma cell line represents a useful tool to study the molecular functions of opioid receptors.

Bone Neoplasms↗
PubMed1986

Perioperative elective. Developing a successful course.

The rapid advances in medical technology have increased the number of potential learning experiences. For example, when the elective was originally planned, laser surgery was not available in the community. Now, a perioperative nurse offers continuing education courses on laser surgery. Freestanding surgical centers have their own specialties (eg, eye clinics), and perioperative nurses specialize within these fields. Ambulatory surgical centers are creating another specialty, such as home health care within the first 24 hours of surgery. Baccalaureate nursing programs need to offer electives for students to explore their interests. Thorough planning of the perioperative elective can ensure its successful implementation. At ASU, the curriculum committee approved the proposed course with few questions, and the hospitals and freestanding clinics readily accepted the students. A perioperative elective is a satisfying experience for instructors who like to teach surgical nursing and work with registered nurses and motivated students.

Arizona↗
PubMed1985

In vivo opiate receptor binding of oripavines to mu, delta and kappa sites in rat brain as determined by an ex vivo labeling method.

The relative in vivo receptor affinities of three oripavine drugs given subcutaneously were determined at the mu, delta and kappa type of opiate binding sites in rat brain. The oripavines include the agonist etorphine, the antagonist diprenorphine and the mixed agonist-antagonist buprenorphine. With the use of mu, delta and kappa specific labeling conditions in brain homogenates immediately after sacrifice (ex vivo labeling), the method relies on the assay of those receptor sites that remain unbound in vivo. Because of the slow receptor binding kinetics of the oripavines, little or no dissociation of the in vivo ligand occurs during the ex vivo labeling period. All three drugs displayed lower affinity in vivo at the delta sites relative to mu sites, whereas the kappa affinities were highly variable. Etorphine displayed considerable mu selectivity, while burpenorphine's affinity at the mu and kappa sites was similar. The apparent in vivo binding affinities obtained from the ex vivo labeling approach are compatible with previous results where tracers were applied in vivo. The dramatic differences of the in vivo and in vitro opiate receptor binding properties of the oripavines demonstrate the need for in vivo receptor binding parameters in the analysis of the function of individual receptor types.

Animals↗
PubMed1985

In vivo binding of benzomorphans to mu, delta and kappa opioid receptors: comparison with urine output in the rat.

In vivo binding affinities of three benzomorphans, Win 44,441-3, bremazocine and MR 2266, were determined at the mu, delta and kappa types of opioid binding sites in rat brain, using an ex vivo labeling technique. The receptor occupancy of the benzomorphans and of previously tested diprenorphine were compared with their activities in increasing urine output (agonist ED50: bremazocine) or inhibiting bremazocine-induced diuresis (antagonist ID50: Win 44,441-3, MR 2266 and diprenorphine). The agonist, bremazocine, bound (in order of decreasing affinity) to the kappa approximately equal to mu greater than delta binding sites, and it's pharmacological effects appeared in the dosage range of kappa and mu binding. In order to positively identify which receptor type is responsible, the potency of the three antagonists to block the effects of bremazocine were compared to their ability to occupy the individual sites in vivo. A fractional occupancy of 0.5 would be expected at the ID50 if one assumes a linear relationship between receptor occupancy by the antagonist and the antagonistic effect. Such a linear relationship was observed for the three antagonists only at the kappa site, whereas variable occupancies were observed at the mu and delta sites. These results support the previously proposed hypothesis that kappa receptors mediate the effects of benzomorphan opioid drugs on urine flow.

Animals↗