Effects of Hypoxia and Anoxia on the Ex Vivo Release of Prostaglandins from Mouse Cortical Slices

Arachidonic acid is transiently accumulated in the brain as a result of a variety of pathological conditions. The synthesis and release of some of its metabolites, namely, prostaglandin E2 (PGE2), thromboxane B2 (TXB2), and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) from cortical slices of mice were studied following exposure to 6 min of hypoxia (7% O2), 45 s of anoxia, and 5 min-4 h of reoxygenation following anoxia. Hypoxia induced a slight increase in the rate of TXB2 release and a slight decrease in the rate of PGE2 release, whereas 6-keto-PGF1 alpha was unaffected. Anoxia (45 s) followed by reoxygenation induced a transient increase in the release of PGE2 and of 6-keto-PGF1 alpha with a return to the normal rate at 30 min and 2 h of recovery, respectively. However, the rate of TXB2 synthesis and release reached its peak (twofold increase) after 1 h and remained significantly higher than the control rate even after 4 h of normal air breathing. Our results demonstrate that hypoxia and anoxia, even of short duration, selectively trigger the activity of thromboxane synthetase and that this elevated rate of synthesis and release persists long after normal oxygen supply is restored. We suggest that enhanced thromboxane synthesis, with normal prostacyclin levels, might have a role in the pathophysiology of ischemic cell damage.     

Prenylated bianthrones and vismione F from Psorospermum febrifugum

The roots of Psorospermum febrifugum collected in Malawi contained together with the known vismione D and geranyloxyemodin four new compounds: vismione F and the three bianthrones A₁, A_3a and A_3b. All the isolated compounds contained C- or O-geranyl substituents and showed a close biogenetic relationship.     

Comparison of Three 18F-Labeled Butyrophenone Neuroleptic Drugs in the Baboon Using Positron Emission Tomography

The butyrophenone neuroleptics spiroperidol, benperidol, and haloperidol were radiolabeled with fluorine-18 and studied in baboon brain using positron emission transaxial tomography (PETT). Pretreatment of the baboon with a high pharmacological dose of (+)-butaclamol reduced the specifically bound component of radioactivity distribution in the striatum to approximately the radioactivity distribution found in the cerebellum. Comparative studies of brain distribution kinetics over a 4-h period indicated that either [18F]spiroperidol or [18F]benperidol may be suitable for specific labeling of neuroleptic receptors. In an 8-h study with [18F]spiroperidol, striatal radioactivity did not decline, suggesting that spiroperidol either has a very slow dissociation rate or that it binds irreversibly to these receptors in vivo. [18F]Haloperidol may not be suitable for in vivo PETT studies, because of a relatively high component of nonspecific distribution and a faster dissociation from the receptor. Analysis of 18F in plasma after injection of [18F]spiroperidol indicated rapid metabolism to polar and acidic metabolites, with only 40% of the total radioactivity being present as unchanged drug after 30 min. Analysis of the metabolic stability of the radioactively labeled compound in rat striatum indicated that greater than 95% of [18F]spiroperidol remains unchanged after 4 h.     

31P and19F NMR studies of glycophorin-reconstituted membranes: Preferential interaction of glycophorin with phosphatidylserine

Summary Glycophorin A, a major glycoprotein of the erythrocyte membrane, has been incorporated into small unilamellar vesicles composed of a variety of pure and mixed phospholipids. Nuclear spin labels including³¹P and¹⁹F have been used at natural abundance or have been synthetically incorporated in lipids to act as probes of lipid-protein interaction. Interactions produce broadening of resonances in several cases and it can be used to demonstrate preferential interaction of certain lipids with glycophorin.³¹P and¹⁹F probes show a strong preferential interaction of glycophorin with phosphatidylserine over phosphatidylcholine. There is some evidence that interactions are more pronounced at the inner surface of the bilayer and these results are rationalized in terms of the asymmetric distribution of protein and lipid.     

Molecular cloning of the F8 fimbrial antigen from Escherichia coli

Abstract The genetic determinant coding for the P-specific F8 fimbriae was cloned from the chromosome of the Escherichia coli wild-type strain 2980 (O18:K5:H5:F1C, F8). The F8 determinant was further subcloned into the Pst I site of pBR322 and a restriction map was established. In a Southern hybridization experiment identity between the chromosomally encoded F8 determinant of 2980 and its cloned counterpart was demonstrated. The cloned F8 fimbriae and those of the wild type strain consist of a protein subunit of nearly 20 kDa. F8 fimbriated strains were agglutinated by an F8 polyclonal antiserum, caused mannose-resistant hemagglutination and attached to human uroepithelial cells. The cloned F8 determinant was well expressed in a variety of host strains.     

In vitro sensitization to transplantation antigens. VII. Enhanced graft-vs-host activity of in vitro allosensitized lymphoid cells

We have previously demonstrated that C57BL/6J lymphoid cells sensitized in vitro to C3H/He transplantation antigens, present on macrophage monolayers, can transfer an accelerated C3H allograft response to recipient C57 mice. The present report indicates that C57 lymphoid cells sensitized to C3H alloantigens, present on macrophage monolayers, can also mediate a graft-versus-host (GVH) reaction in (C3H × C57) F₁ newborn mice. This GVH reaction is of greater magnitude than that produced by noncultured C57 cells. The magnitude of the augmented GVH reaction produced by cultured C57 cells is dependent on the source of lymphoid cells: lymph node, spleen, and bone marrow cells are consistently more active than cultured thymus cells—the reduced capability of cultured thymus cells to mediate the GVH reaction parallels their reduced ability to transfer allograft immunity. To test whether monolayers, other than macrophages, can sensitize lymphoid cells in vitro we incubated C57 lymphoid cells on C3H-derived L cells. Lymph node cells incubated with L cells demonstrate an increased GVH reaction in newborn mice. The in vitro sensitization of spleen and bone marrow cells on L cells is less consistent. Thymus cannot be sensitized by L cells. Monolayers of L cells are therefore not as efficient a sensitizing source as macrophages.     

Regulation of insulin synthesis in an insulin-producing cell line (RINm5F): Long-term experiments

Summary The insulin-producing cell line RINm5F, has been used in short-term experiments to evaluate insulin secretion. We sought to maintain the responsiveness of these cells to stimuli for up to 2 days. We examined the course of new insulin synthesis over this period by measuring at intervals immunoreactive insulin (IRI) in two parts: IRI in the medium (M) and IRI extracted from the cells (C). Control cells were incubated in RPMI 1640/2.8 mM glucose/10% fetal bovine serum/200 μg/ml bacitracin (to prevent insulin degradation). The addition of dibutyryl cAMP 10 mM to the experimental dishes significantly increased total (M+C) IRI at 48 hr to 37% above the insulin content of the control dishes (p<0.01). Theophylline 10 mM increased total (M+C) IRI by 24% over control (p<0.05) after 24 hrs. Glucose, glyceraldehyde, leucine, arginine, glucagon and tolbutamide, other stimulants of insulin production, had no effect. Under the experimental conditions reported here, including the use of bacitracin, IRI synthesis can be studied for up to 48 hr. Portions of this study have been published in abstract form for the 47th Annual Meeting of the American Diabetes Association, Indianapolis, Indiana, 1987. Supported in part by the American Diabetic Association, Maryland Affiliate.     

黄山贝母和天目贝母的核型研究

本文首次报道了产于江西的黄山贝母(F.huangshanensis Y. K. Yanget C. J. Wu)和浙江的天目贝母(F. monantha Migo)的核型:前者为2n=24=2m 2sm 6st(4sc) 14t;后者为2n=24=2m 2sm 6st(4sc) 14t(2sc)。此外,与国内报道的其它贝母属植物的核型进行了比较和讨论。     

Roles of Escherichia coli heat shock proteins DnaK, DnaJ and GrpE in mini-F plasmid replication

Summary A subset of Escherichia coli heat shock proteins, DnaK, DnaJ and GrpE were shown to be required for replication of mini-F plasmid. Strains of E. coli K12 carrying a missense mutation or deletion in the dnaK, dnaJ, or grpE gene were virtually unable to be transformed by mini-F DNA at the temperature (30° C) that permits cell growth. When excess amounts of the replication initiator protein (repE gene product) of mini-F were provided by means of a multicopy plasmid carrying repE, these mutant bacteria became capable of supporting mini-F replication under the same conditions. However, the copy number of a high copy number mini-F plasmid was reduced in these mutant bacteria as compared with the wild type in the presence of excess RepE protein. Furthermore, mini-F plasmid mutants that produce altered initiator protein and exhibit a very high copy number were able to replicate in strains deficient in any of the above heat shock proteins. These results indicate that the subset of heat shock proteins (DnaK, DnaJ and GrpE) play essential roles that help the functioning of the RepE initiator protein in mini-F DNA replication.     

The 21-aminosteroid U-74389F increases the number of glial fibrillary acidic protein-expressing astrocytes in the spinal cord of control and wobbler mice

Summary 1. Wobbler mice suffer an autosomal recessive mutation producing severe motoneuron degeneration and dense astrogliosis, with increased levels of glial fibrillary acidic protein (GFAP) in the spinal cord and brain stem. They have been considered animal models of amyotrophic lateral sclerosis and infantile spinal muscular atrophy. 2. Using Wobbler mice and normal littermates, we investigated the effects of the membrane-active steroid Lazaroid U-74389F on the number of GFAP-expressing astrocytes and glucocorticoid receptors (GR). Lazaroids are inhibitors of oxygen radical-induced lipid peroxidation, and proved beneficial in cases of CNS injury and ischemia. 3. Four days after pellet implantation of U-74389F into Wobbler mice, hyperplasia and hypertophy of GFAP-expressing astrocytes were apparent in the spinal cord ventral and dorsal horn, areas showing already intense astrogliosis in untreated Wobbler mice. In control mice, U-74389F also produced astrocyte hyperplasia and hypertophy in the dorsal horn and hyperplasia in the ventral-lateral funiculi of the cord. 4. Givenin vivo U-74389F did not change GR in spinal cord of Wobbler or control mice, in line with the concept that it is active in membranes but does not bind to GR. Besides, U-74390F did not compete for [³H]dexamethasone binding when addedin vitro. 5. The results suggest that stimulation of proliferation and size of GFAP-expressing astrocytes by U-74389F may be a novel mechanism of action of this compound. The Wobbler mouse may be a valuable animal model for further pharmacological testing of glucocorticoid and nonglucocorticoid steroids in neurodegenerative diseases.