Localization of Arbutin in Pyrvs by Means of Alkaline P-Phenylenediamine

A reagent composed of 0.2% p-phenylenediamine in 2 N NH₄OH was used for the cytochemical demonstration of arbutin in plant tissue. Sections of fresh tissue were cut at 25-50 μ, mounted in a drop of the reagent, and allowed to stand uncovered 15-20 min before applying a coverslip. Arbutin stained dark blue to dark purple and was easily distinguished from other constituents of the cell, such as chlorogenic acid, isochlorogenic acid, caffeic acid, and quinic acid, which stained yellow, yellow-green, red or brown in color. The limit of sensitivity of the p-phenylenediamine-arbutin reaction was 1:100,000, as determined by spot-plate tests.     

Effect of lead on blood protoporphyrin levels of a group of ring teal ducks (Callonetta leucophrys)

This research determined the relationships between blood lead level and zinc protoporphyrin (ZnPROTO), protoporphyrin IX (PROTO), and free erythrocyte protoporphyrin (FEP) levels in a group of 18 ring teal ducks. Blood samples were drawn from two groups of ring teal ducks as part of the routine health maintenance program of the New York Zoological Park. One group of six teals had been exposed to what is believed to be lead-contaminated dust, while the second group of twelve teals was unexposed. Blood samples were analyzed for lead by flameless atomic absorption and for protoporphyrins by fluorescence. Blood lead level and log blood lead level had positive correlations with each of the protoporphyrins: the logarithmic correlations were better than the nonlogarithmic correlations, and PROTO correlated better than ZnPROTO. With one exception, PROTO levels were higher than ZnPROTO levels. The results suggest that PROTO, FEP, or ZnPROTO could serve as a biological indicator of lead poisoning in ring teal ducks.     

Dietary and prophylactic iron supplements

Mild hypoferremia represents an aspect of the ability of the body to withhold iron from pathogenic bacteria, fungi, and protozoa, and from neoplastic cells. However, our iron-withholding defense system can be thwarted by practices that enhance iron overload such as indiscriminate iron fortification of foods, medically prescribed iron supplements, alcohol ingestion, and cigarette smoking. Elevated standards for normal levels of iron can be misleading and even dangerous for individuals faced with medical insults such as chronic infection, neoplasia, cardiomyopathy, and arthritis. We are becoming increasingly aware that the wide-spread hypoferremia in human populations is a physiological response to insult rather than a pathological cause of insult, and that attempts to correct the condition by simply raising iron levels may not only be misguided but may actually impair host defense.     

Immunohistochemical distribution of basic fibroblast growth factor in experimental retinal ischaemia and reperfusion in the rat

Summary It has been proposed that basic fibroblast growth factor (basic FGF) mediates the neovascular response in a variety of conditions, including diabetic retinopathy and branch retinal vein occlusion. To test the hypothesis that basic FGF was released from retinal stores as a result of retinal ischaemia, transient retinal ischaemia was induced, followed by 48 h of reperfusion, in the rat by combined central retinal vasculature and optic nerve ligation. The immunolocalization of basic FGF was studied in the retina. We found that basic FGF in the normal retina is present around the deeper retinal vessels and in the neuronal tissue of the outer plexiform layer. In the eyes that had ischaemia followed by reperfusion, there was moderate cellular oedema with retinal swelling, and mitoses in the inner nuclear and plexiform layers. There were no changes evident at the immunohistochemical level either in the intensity or distribution of stores of basic FGF. We conclude from these data that stores of basic FGF are not altered dramatically under the conditions of transient experimental ischaemia and reperfusion in the rat, despite the presence of cellular proliferation.     

Suppression of programmed neuronal death by a thapsigargin-induced Ca2+ influx

Rat sympathetic neurons undergo programmed cell death (PCD) in vitro and in vivo when they are deprived of nerve growth factor (NGF). Chronic depolarization of these neurons in cell culture with elevated concentrations of extracellular potassium ([K⁺]_o) prevents this death. The effect of prolonged depolarization on neuronal survival is thought to be mediated by a rise of intracellular calcium concentration ([Ca²⁺]_i) caused by Ca²⁺ influx through voltage-gated channels. In this report we investigate the effects of chronic treatment of rat sympathetic neurons with thapsigargin, an inhibitor of intracellular Ca²⁺ sequestration. In medium containing a normal concentration of extracellular Ca²⁺ ([Ca²⁺]_o), thapsigargin caused a sustained rise of intracellular Ca²⁺ concentration and partially blocked death of NGF-deprived cells. Elevating [Ca²⁺]_o in the presence of thapsigargin further increased [Ca²⁺]_i, suggesting that the sustained rise of [Ca²⁺]_i was caused by a thapsigargin-induced Ca²⁺ influx. This treatment potentiated the effect of thapsigargin on survival. The dihydropyridine Ca²⁺ channel antagonist, nifedipine, blocked both a sustained elevation of [Ca²⁺]_i and enhanced survival caused by depolarization with elevated [K⁺]_o, suggesting that these effects are mediated by Ca²⁺ influx through L-type channels. Nifedipine did not block the sustained rise of [Ca²⁺]_i or enhanced survival caused by thapsigargin treatment, indicating that these effects were not mediated by influx of Ca²⁺ through L-type channels. These results provide additional evidence that increased [Ca²⁺]_i can suppress neuronal PCD and identify a novel method for chronically raising neuronal [Ca²⁺]_i for investigation of this and other Ca²⁺-dependent phenomena. © 1995 John Wiley & Sons, Inc.     

The Structure and Origin of the Plasmodium of Rhopalura ophiocomae(Phylum Orthonectida)

Abstract Adult orthonectids develop from germinal cells within a cytoplasmic matrix called a plasmodium. This is generally assumed to be formed by the parasite. In the case of Rhopalura ophiocomae, which lives in the brittle star Amphipholis squamata, the plasmodia occupying the perivisceral coelom are closely associated with the walls of the genital bursae or the gut, and they are covered by peritoneum. They have been reported to contain scattered small nuclei distinct from those within germinal cells, embryos, and adults, but the results of the present study indicate that such nuclei probably do not exist. Furthermore, electron micrographs show that some plasmodia are in continuity with the cytoplasm of contractile cells that lie beneath the peritoneum of a genital bursa or the gut of the host. The matrix of a plasmodium of R. ophiocomaeappears, therefore, to consist of cytoplasm of a contractile cell. It is proposed that after a contractile cell has been entered by an infective cell of the parasite, it hypertrophies, bulging progressively farther into the perivisceral coelom and lifting up the peritoneum, which remains in intimate contact with it.     

The potential energy surface of methyl 3-O-(α-D-mannopyranosyl)-α-D-mannopyranoside in aqueous solution: Conclusions derived from optical rotation

The optical rotation of methyl 3-O -(α-D -mannopyranosyl)-α-D -mannopyranoside is calculated semiempirically as a function of the linkage dihedral angles ? (H1-C1-O1-C3′) and ψ (C1-O1-C3′-H3′). Comparison with the observed optical rotation in aqueous solution indicates the existence of at least two conformers in solution, which implies a degree of linkage flexibility. The result is in agreement with some, but not all, calculated potential energy surfaces, and with recently published nmr data. © 1994 John Wiley & Sons, Inc.     

The potential energy surface of methyl 2-O-(α-D-mannopyranosyl)-α-D-mannopyranoside in aqueous solution: Conclusions derived from optical rotation

The optical rotation of methyl 2-O -(α-D -mannopyranosyl)-α-D -mannopyranoside is calculated semiempirically as a function of the linkage dihedral angles ? (H1-C1-O1-C2′) and ψ (C1-O1-C2′-H2′). Although the rotation calculated for the global energy minimum conformation found in several rigid-residue modeling calculations (?,ψ = ?40°,?20°) is in good agreement with the observed solution rotation, the observed rotation is also compatible with the limited flexibility inferred from more recent relaxed residue modeling calculations on a structurally related rhamnose disaccharide © 1994 John Wiley & Sons, Inc.     

Agents that Promote Protein Phosphorylation Inhibit the Activity of the Na+/Ca2+ Exchanger and Prolong Ca2+ Transients in Bovine Chromaffin Cells

Abstract: The Na⁺/Ca²⁺ exchanger is an important element in the maintenance of calcium homeostasis in bovine chromaffin cells. The Na⁺/Ca²⁺ exchanger from other cell types has been extensively studied, but little is known about its regulation in the cell. We have investigated the role of reversible protein phosphorylation in the activity of the Na⁺/Ca²⁺ exchanger of these cells. Cells treated with 1 m M dibutyryl cyclic AMP (dbcAMP), 1 µ M phorbol 12,13-dibutyrate, 1 µ M okadaic acid, or 100 n M calyculin A showed lowered Na⁺/Ca²⁺ exchange activity and prolonged cytosolic Ca²⁺ transients caused by depolarization. A combination of 10 n M okadaic acid and 1 µ M dbcAMP synergistically inhibited Na⁺/Ca²⁺ exchange activity. Conversely, 50 µ M 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine, a protein kinase inhibitor, enhanced Na⁺/Ca²⁺ exchange activity. Moreover, we used cyclic AMP-dependent protein kinase and calcium phospholipid-dependent protein kinase catalytic subunits to phosphorylate isolated membrane vesicles and found that the Na⁺/Ca²⁺ exchange activity was inhibited by this treatment. These results indicate that reversible protein phosphorylation modulates the activity of the Na⁺/Ca²⁺ exchanger and suggest that modulation of the exchanger may play a role in the regulation of secretion.