Purification and characterization of vitellin-2 from the ovary of the American cockroach, Periplaneta americana

Two vitellins (Vn-1 and Vn-2) were identified in cockroach ovary. Vn-2 was purified by ion-exchange chromatography using DEAE cellulose and Sepharose CL-6B, and gel filtration using Sephadex G-200 and Sepharose 4B. Vn-2 comprises three subunits with molecular weights of 102, 72 and 40 kDa. Vn-2 contains diacylglycerol and triacylglycerol; their fatty acids are mostly lauric acid and palmitoleic acid. Vn-2 also has phosphatidylcholine and phosphatidylethanolamine but no sphingomyelin. Vn-2 contains large amounts of glutamic acid and aspartic acid but small amounts of tyrosine, phenylalanine, and methionine. Vn-2 gradually decreases during embryonic development; none remains in first instar larvae. It was found that Vn-2 partially reacted immunologically with ovarian extracts of Periplaneta fulginosa but not with those of Blattella germanica. Vn-2 also showed no immunological reaction with extracts from other orders; including Cletus schmidti (Hemiptera), Lucilia illustris (Diptera), Anechura japonica (Dermaptera), Bombyx mori (Lepidoptera), and Ducetia japonica (Orthoptera).

Function of NAD glycohydrolase in ADP-ribose uptake from NAD by human erythrocytes

The function of the ectoenzyme NAD glycohydrolase (NADase) in ADP-ribose uptake from extracellular NAD was studied in human erythrocytes that express relatively high NADase activity (adult erythrocytes) and erythrocytes expressing very low activity (newborn erythrocytes). The rates of ADP-ribose uptake from NAD in human erythrocytes were correlated with their NADase activities. In contrast, there was no significant difference in the rates of ADP-ribose uptake among these cells when incubated with ADP-ribose. These results indicate that ecto-NADase may have a role as supplier of ADP-ribose for its uptake into the cells and that the cleavage of NAD by NADase is necessary for the ADP-ribose uptake by human erythrocytes. From ADP-ribose uptake studies at 37 degrees C a Km of 0.7 +/- 0.05 microM and a Vmax of 2.04 +/- 0.1 pmol/min per microliter cell water was found for the uptake of [3H]ADP-ribose. The thiol-reactive reagents p-chloromercuribenzene sulfonic acid and N-ethylmaleimide inhibited the uptake ADP-ribose with IC50 values of 50 +/- 4 and 750 +/- 25 mM, respectively. Since efflux of [3H]ADP-ribose was negligible, the ADP-ribose transport system appears to be unidirectional. The unidirectionality was supported by the evidence that transported ADP-ribose was rapidly degraded to AMP which is impermeable to the membrane.

Purification and characterization of NAD glycohydrolase from rabbit erythrocytes

The NAD glycohydrolase (NADase) was solubilized from intact erythrocytes with bacterial phosphatidylinositol-specific phospholipase C and purified to homogeneity by affinity chromatography on Cibacron blue-agarose. This purification procedure resulted in an approximately 85-fold purification with an overall recovery of 75%. The purified NADase has a molecular weight of 65,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 63,000 as determined by gel permeation column chromatography at pH 7.0. Two hybridoma cell lines secreting antibodies against NADase were established and the antibodies recognized the purified enzyme as well as a 65-kDa band from the extracts of rabbit erythrocyte ghost. The enzyme displayed a Km of 43 microM for beta-NAD, a Vmax of 23 mumol/min/mg, a broad pH optimum around pH 7.0, and pI of 5.0. Nicotinamide and isoniazid are inhibitors (Ki values, 2.5 and 3.5 mM, respectively) of the noncompetitive type. Adenosine diphosphoribose acts as a competitive inhibitor (Ki = 2.0 mM). Cibacron blue 3GA is a potent competitive inhibitor of NADase (Ki = 96 nM). The purified enzyme splits beta-NAD, NADP, and nicotinamide hypoxanthine dinucleotide among the compounds tested and does not exhibit transglycosidase activity. Amino acid composition of the rabbit erythrocyte enzyme differed from that of NADases of other species, and the purified NADase contains 8% carbohydrate and a stoichiometric amount of inositol.

Mapping of nucleic acid binding in proteolytic domains of HIV-1 reverse transcriptase

Human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT) and its domain fragments were used to map nucleic acid binding sites within the enzyme. Discrete domain fragments were produced after the digestion of three forms of RT (p66, p66/p51 heterodimer, and p51) with V8 protease or trypsin, and the primary structure of each domain fragment was mapped by both immunoblotting and N-terminal amino acid sequence analysis. These domain fragments represent N-terminal, middle, or C-terminal regions of RT. Using Northwestern or Southwestern blotting assays, the domain fragments were evaluated for nucleic acid binding. In this technique, RT proteins are electroblotted onto the membrane and renatured after SDS-PAGE; the proteins are then probed with the primer analogues 32P-labeled d(T)16 or 32P-labeled tRNA(Lys,3). A V8 protease domain fragment spanning residues 195 to approximately 300 (p12), which was found earlier to be UV cross-linked to the primer in intact RT [Sobol et al. (1991) Biochemistry 30, 10623-10631], showed binding to both nucleic acid probes. We first localized nucleic acid binding in p66 to an N-terminal domain fragment of residues 1 approximately equal to 300. By contrast, a C-terminal domain fragment termed p30(303 approximately equal to 560) did not show nucleic acid binding. To investigate the role of the region just N-terminal to residue 303, an expression vector named pRC-35 encoding residues 273-560 was constructed.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemolytic mechanism of cytolysin produced from V. vulnificus

The characteristics of hemolytic action of cytolysin produced from V. vulnificus were investigated in mouse erythrocytes. The cytolysin bound erythrocyte membranes in temperature-independent manner and then lysed cells temperature-dependently. Hemoglobin release by the cytolysin was completely inhibited by the presence of raffinose or melezitose, but K+ release was not affected. The cytolysin-induced hemolysis was always accompanied with the conversion of membrane-bound cytolysin into an oligomer of 210 kDa, corresponding to a tetramer of native cytolysins. Nonesterified cholesterol inactivated the cytolysin by converting active monomeric cytolysin into inactive oligomer. The results suggest that the cytolysin lyses erythrocytes due to the formation of small pores on erythrocyte membrane by cholesterol-mediated oligomerization of the cytolysin.

Three cases of congenital hepatic fibrosis with Caroli's disease in three siblings

Congenital hepatic fibrosis is a relatively rare disease of children and young adults characterized by hard hepatomegaly, portal hypertension with relative preservation of liver function and underlying architecture, and frequent renal involvement. We experienced 3 cases of congenital hepatic fibrosis with Caroli's disease in 3 siblings, whose clinical manifestations were diverse, such as repeated cholangitis, variceal hemorrhage, or intrahepatic stones. All of them had multiple renal cysts, so we supposed that the clinical entities of these patients were in the spectrum of fibropolycystic disease of the liver and kidney.

Prophylactic medication for unipolar depressive illness: the place of lithium carbonate in combination with antidepressant medication

A meta-analysis of the controlled clinical trials comparing the efficacy of combined lithium-imipramine therapy with each drug alone in the prevention of relapse in patients with unipolar depressive illness shows the combination to be superior to lithium alone (for any relapse, p less than 0.05; for specifically depressive relapse, p less than 0.025) and imipramine alone (for any relapse, p less than 0.025; for specifically depressive relapse, p less than 0.05). The issue of statistical power in studies of this kind is discussed. A single case of unipolar depressive illness is described, in which combined lithium-tranylcypromine therapy was superior to either drug alone. A combination of lithium and an antidepressant should be considered for any patient suffering from this condition who fails to remain well on either drug alone.

Two chicken erythrocyte band 3 mRNAs are generated by alternative transcriptional initiation and differential RNA splicing

The erythrocyte anion transport protein (band 3) mediates two distinct cellular functions: it provides plasma membrane attachment sites for the erythroid cytoskeletal network, and it also functions as the anion transporter between the erythrocyte cytoplasm and extracellular milieu. We previously showed that two chicken band 3 polypeptides are encoded by two different mRNAs with different translation initiation sites. Here we show that these two band 3 mRNAs are transcribed from two separate promoters within a single gene. In addition, the two pre-mRNAs are differentially spliced, leading to fusion with coding exons used in common in the two mRNAs. The chicken erythrocyte band 3 gene is therefore the first example of a gene that has two promoters within a single locus which function equally efficiently in one cell type at the same developmental stage.

Two different mRNAs are transcribed from a single genomic locus encoding the chicken erythrocyte anion transport proteins (band 3)

The chicken erythrocyte anion transport protein (band 3 of the erythrocyte cytoskeleton) is a central component taking part in two widely divergent functions of erythroid cells; it is a primary determinant of cytoskeletal architecture and responsible for electroneutral Cl-/HCO3- exchange across the plasma membrane. To analyze interesting aspects of the developmental regulation of this gene, we have cloned the cDNA and genomic counterparts of the erythroid-specific anion transport protein. We show that a single genetic locus for band 3 encodes two different erythroid cell-specific mRNAs, with different translational initiation sites, which predict polypeptides of sizes very close to those observed in vivo. In vitro translation and immune precipitation of synthetic mRNA derived from one putative fully encoding cDNA clone demonstrate that this clone gives rise to a protein which is identical in size and antigenicity to bona fide chicken erythroid band 3.

Membrane-associated NAD+ glycohydrolase from rabbit erythrocytes is solubilized by phosphatidylinositol-specific phospholipase C

NAD+ glycohydrolase (NADase) present on the surface of rabbit erythrocytes is a membrane-bound ectoenzyme that can be solubilized by phosphatidylinositol-specific phospholipase C (PIPLC). As much as 70% of the cell-associated NADase was made soluble by treatment with PIPLC. The portion of NADase that remained cell-associated after an initial PIPLC treatment proved to be resistant to subsequent solubilization attempts. Further analysis showed that release of NADase from erythrocytes could not be attributed to the action of proteinases or phospholipase C. Erythrocytes obtained from other mammals were analyzed and found to have variable amounts of PIPLC-susceptible NADase. Practically, this finding can be used to easily solubilize membrane-bound NADase as a first step in its purification.

Distribution and immunochemical character of neurotensin-like material in representative vertebrates and invertebrates: apparent conservation of the COOH-terminal region during evolution

Using a radioimmunoassay for bovine neurotensin (NT) and various region specific antisera which react selectively with different portions of the molecule, the presence of immunoreactive NT (iNT) in a wide range of vertebrate and invertebrate species has been demonstrated. While antisera directed towards the N-terminal region of NT recognized only mammalian forms of NT, antisera directed towards the C-terminal region of NT recognized materials from all species examined, including representatives of all vertebrates and invertebrate classes. When extracts of the brain and gut of the vertebrates examined were chromatographed on Sephadex G-25 multiple NT-like substances were observed, and the patterns of iNT obtained seemed to fall into three groups: (a) mammals, (b) birds and reptiles and (c) amphibians and fish. Extracts of invertebrates also exhibited multiple peaks of iNT on Sephadex G-25 and the profiles observed resembled those for lower vertebrates. Partially purified iNT obtained from chicken, turtle, dogfish and lobster was shown to increase hematocrit and induce cyanosis in anesthetized rats. These findings indicate (a) that NT-like substances appear to be present throughout the animal kingdom, (b) that the C-terminal region of NT is highly conserved while the N-terminal region varies, and (c) that in any one animal multiple substances sharing C-terminal homologies with NT exist. These findings are consistent with the notion that NT and related peptides participate in important processes basic to animal life and that their functioning depends highly upon elements located in their C-terminal regions. They further suggest the existence of an entire family of NT-related peptides in each animal form, possibly distributed differently and functioning differently in the various organs of the animal.

Skeletal scintigraphy following incidental trauma

The significance of antecedent trauma in skeletal scintigraphy was assessed in 503 patients, of whom 241 (46%) had prior fracture or tooth extraction. In patients with sufficiently accurate histories for site-by-site analysis, 33 of 131 fracture sites and 16 of 83 dental-procedure sites were positive scintigraphically. In general, the frequency of scan positivity diminished as the interval between trauma and scanning increased, but a significant number of patients showed prolonged uptake at fracture sites. Several patterns of uptake suggested trauma rather than metastatic disease. Knowledge of a history of trauma is often critical in bone scan interpretation.

Toadfish serum as a binder for in vitro assay of vitamin B12

Serum from the oyster toadfish, Opsanus tau, has a binding capacity for cyanocobalamin 1,000 times greater than that of human serum. The binding follows the principle of isotope dilution in the physiologic range of vitamin B12 present in human serum. Under proper conditions of storage, this binder is stable for at least 1 year. Standard reagents and techniques used in other vitamin B12 competitive binding assays can be used with the toadfish serum binder. Toadfish serum offers potential advantages over intrinsic factor and human serum, the most commonly used binders in vitamin B12 assays.