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Biomedical subjects

B A Larson

Publications and source records attributed to B A Larson.

At least 19 recordsLinked to original sources
PubMed1991

Increased urotensin I and II immunoreactivity in the urophysis of Gillichthys mirabilis transferred to low salinity water.

The function of the fish caudal neurosecretory system is uncertain, but a role in osmoregulation has been suggested by many investigators. Our objective was to determine if acclimation to water of different salinity has an effect on immunoreactive patterns and staining intensities of the two caudal neuropeptides, urotensins I (UI) and II (UII), in Gillichthys mirabilis. Five fish, originally maintained in seawater, were transferred to deionized fresh water (FW), and five were transferred to new seawater (SW). After 24 hr spinal cords were removed and fixed, FW and SW spinal cords were paired in blocks to receive identical treatment, and cryostat sections were double immunostained for both peptides using a double sequential immunofluorescence procedure. FW spinal cord exhibited increased staining intensities for both UI and UII in their urophyses (the neurohemal organ) compared to the SW spinal cords. The magnitude of intensity difference appeared greater for UI than for UII. In addition, the FW urophyses had more loci displaying intense, perivascular UI immunoreactivity than the SW urophyses. Thus, it appears that environmental salinity has an effect on the urophysial content of UI and UII in this euryhaline fish. The increased immunoreactivity in FW fish could reflect increased synthesis and storage, decreased release of the stored peptides, or decreased peptide degradation.

Adaptation, Physiological↗
PubMed1991

Rat endometrial stromal-epithelial response to estrogen infusion.

Morphologic changes at the interface of rat endometrial luminal epithelial cells and the stromal cells immediately adjacent were examined and correlated with hypertrophy of the epithelial cells during estradiol (E2) infusion (1 microgram E2/24 h). While the lamina densa in castrate endometrium was thread-like, it became thicker and apparently more granular in some areas below the luminal epithelium during E2 infusion. However, no changes were seen in the intensity of laminin-like immunoreactivity at various time points up to 96 hours after beginning infusion, suggesting that these alterations were due to changes in nonlaminin components. The stromal cells adjacent to the basal lamina in the castrate state had cell processes extending toward the epithelium that terminated on the basal lamina. Under estrogen infusion, stromal cell bodies migrated close to and became oriented along the basal lamina. No interruptions were seen in the lamina densa or in the laminin-like immunoreactivity in the basal lamina. Thus, there were no direct morphologic interactions between epithelial and stromal cells induced by estrogen. Some of the stromal cells developed a dilated rough endoplasmic reticulum and some developed multiple elaborate processes within 41 hours after minipump implantation. Within 28 hours, nuclear hypertrophy had occurred in 15% of the epithelial cell layer. If interactions occur between stromal and epithelial cells, and morphologic evidence presented here suggests they do, then all such interactions are through an intact lamina densa-laminin layer, and any chemical mediators affecting cells on opposite sides of the lamina densa must migrate through it.

Animals↗
PubMed1990

Words can hurt. Dealing with verbal abuse in the operating room.

There are rewards for nurse administrators who challenge organizational norms and physician behaviors to support nurses. We found that the term verbal abuse had sparked anger and fear. The spark kindled interest and energy that we converted into a process to support staff nurses in their roles. As we enter the 1990s, the focus is on finding solutions to problems that concern nurses. The advocacy role of the nursing leader requires constant awareness of the nurses' situation within the health care environment and a sensitivity to their needs and rights as professionals. Dealing with the issue of verbal abuse demonstrated to the nursing staff our commitment and support.

Documentation↗
PubMed1987

A double sequential immunofluorescence method demonstrating the co-localization of urotensins I and II in the caudal neurosecretory system of the teleost, Gillichthys mirabilis.

A double immunofluorescence method was devised to localize simultaneously urotensin-I (UI) and -II (UII) immunoreactivities in the caudal neurosecretory system of the goby, Gillichthys mirabilis. In a sequential fashion, sections of the posterior spinal cord and urophysis were treated with antiserum to corticotropin-releasing factor (CRF) that cross-reacts with UI, fluorescein-conjugated sheep anti-rabbit IgG, biotinylated anti-UII and rhodamine-conjugated avidin. UI and UII immunoreactivities appeared to coexist in some neurons and in most fibers and urophysial tissue; the remainder of the fibers and urophysis and the majority of neurons were immunoreactive for CRF/UI only. No convincing evidence of immunoreactivity for UII only was found. A few nonreactive cells were seen, but these may not be neurosecretory neurons. The two immunoreactive cell types were not segregated topographically, and the intensity of perikaryal immunofluorescence for CRF/UI was variable. To explain these results a hypothesis that all caudal neurosecretory cells may synthesize both UI and UII and that immunoreactive differences may reflect different states of cellular activity, is suggested. This sequential double immunofluorescence method offers several advantages over other techniques and is especially useful for co-localization studies when primary antisera from different species are not available.

Animals↗
PubMed1983

Species and tissue distribution of cholecystokinin/gastrin-like substances in some invertebrates.

Twenty-six species of invertebrates representing eight phyla were surveyed for the presence of cholecystokinin/gastrin-like (CCK/gastrin-like) peptides by radioimmunoassay of various tissue extracts. This is the first report of the presence of CCK/gastrin-like peptides in representatives of the phylum Ectoprocta, the arthropodan classes Crustacea and Merostomata, and in the nervous systems of the gastropod mollusc Aplysia californica and the oligochaete annelid Lumbricus terrestris. It has been proposed that CCK/gastrin evolved in the invertebrates as a neural peptide and was subsequently exploited by the vertebrates as a regulatory peptide in both the nervous system and the gastrointestinal endocrine system. The present results indicate that some gastropod molluscs, a merostomatan arthropod, and an annelid have detectable CCK/gastrin in both nervous and gut tissue. However, extractable CCK/gastrin was found only in gut tissue and not in the central nervous system of a crustacean arthropod. The tissue origin of the extracted CCK/gastrin in Bugula (phylum Ectoprocta) was not determined. Final resolution of the question of the nervous versus gut endocrine cellular origin of CCK/gastrin in invertebrates awaits further investigation. CCK/gastrin-like peptides are widely distributed among the invertebrates, which thus provide a rich source of comparative material for study of these regulatory substances.

Animals↗
PubMed1983

Gastrin/cholecystokinin-like immunoreactive peptides in the Dungeness crab, Cancer magister (Dana): immunochemical and biological characterization.

The purpose of this investigation was to characterize a gastrin/cholecystokinin-like immunoreactant (G/CCK-LI) extractable from the crab, Cancer magister. G/CCK-LI was extracted best in boiling water and was found mainly in the stomach, hemolymph and carapace. A relatively large immunoreactive peptide in the stomach and apparently smaller forms in the hemolymph and carapace were separated by Sephadex G-50 fractionation. Anion-exchange chromatography further fractionated the stomach form into three major peaks. The crab material cross-reacted with three antisera specific for the common C-terminus of gastrin/CCK, but cross-reacted much less with three antisera directed against other portions of the gastrin molecule. Partially purified crab stomach G/CCK-LI inhibited the binding of labeled CCK to mouse brain G/CCK receptors but not to rat pancreatic CCK receptors. The crab peptide did not stimulate rat gastric acid or rat pancreatic amylase secretion. These results indicate that the crab peptides are structurally similar to, but distinguishable from, the bioactive C-terminal amino acid sequence common to gastrins and CCKs.

Amylases↗
PubMed1981

Subunit heterogeneity of Cancer magister hemocyanin.

Hemocyanin from the Dungeness crab, Cancer magister, has been described as a 25-S two-hexamer assembly of two different 5-S subunits. We have found that at least six different 5-S polypeptide chains constitute this hemocyanin. They can be separated from one another by sodium dodecyl sulfate slab gel electrophoresis as well as by regular gel electrophoresis. The six 5-S polypeptides appear very different from one another when each SDS-treated subunit is partially digested with Staphylococcus aureus V8 protease. This pattern of six subunits is present both in hemolymph which has been examined immediately upon removal from the animal as well as in hemocyanin which has remained at room temperature for two weeks. Thus, it is unlikely that the heterogeneity is a result of proteolysis during preparation of the sample. Possible implications of the high degree of subunit heterogeneity on the protein's quaternary structure are discussed.

Animals↗
PubMed1979

Effect of 2-deoxyglucose on [32P] phosphate and insulin release from perifused rat pancreatic islets.

The effect of 2-deoxyglucose on glucose mediated insulin and [32P]phosphate release was studied by perifusion of isolated rat pancreatic islets. When islets were perifused with media containing 2.8 mmol/l glucose and 20 mmol/l 2-deoxyglucose for 60 minutes and then exposed to media containing 8.3 or 16.7 mmol/l glucose and 20 mmol/l 2-deoxyglucose for the next 15 minutes, insulin release at either glucose concentration was prompt but blunted. Similarly, islets preincubated (90 min) with [32P] orthophosphate, then perifused with 20 mmol/l 2-deoxyglucose for 75 min and stimulated by either 8.3 or 16.7 mmol/l glucose for the final 15 minutes or 2-deoxyglucose exposure demonstrated obtundation of [32P]phosphate release. Perifusion of islets with 20 mmol/l 2-deoxyglucose alone induced no heightened 32P efflux. These studies suggest that 2-deoxyglucose affects initial events in stimulus-secretion coupling of glucose mediated insulin release.

Animals↗
PubMed1978

Insulin secretion from pancreatic islets: effect of growth hormone and related proteins.

Insulin responses to clinical grade human growth hormone (hGH), intact hGH, naturally occurring diabetogenic substance (NDS), and subtilisin cleaved forms of hGH (S1 and S3) were studied using hypophysectomized rat pancreatic islets. While clinical grade hGH (200 microgram/ml) elicited a prompt and sustained release of insulin, purified intact hGH (200 microgram/ml) did not. Naturally occurring diabetogenic substance, isolated from clinical grade hGH preparations, stimulated insulin release at 200 ng/ml. Upon repeat stimulation with NDS, a significantly greater insulin release than with initial stimulation was observed. Although S3 (200 microgram/ml) elicited significant insulin release, S1 (200 microgram/ml) did not. Direct stimulation of insulin release with clinical grade hGH is not due to intact hGH but another proteins(s) such as NDS. Enzymic modification of intact hGH appears to enhance insulin stimulatory capacity.

Animals↗