Sodium Fluoride Mimics the Effect of Prostaglandin E2 on Catecholamine Release from Bovine Adrenal Chromaffin Cells

We have reported recently that prostaglandin E2 (PGE2) stimulated phosphoinositide metabolism in bovine adrenal chromaffin cells and that PGE2 and ouabain, an inhibitor of Na+, K(+)-ATPase, synergistically induced a gradual secretion of catecholamines from the cells. Here we examined the involvement of a GTP-binding protein(s) in PGE receptor-induced responses by using NaF. In the presence of Ca2+ in the medium, NaF stimulated the formation of all three inositol phosphates, i.e., inositol monophosphate, bisphosphate, and trisphosphate, linearly over 30 min in a dose-dependent manner (15-30 mM). This effect on phosphoinositide metabolism was accompanied by an increase in cytosolic free Ca2+. NaF also induced catecholamine release from chromaffin cells, and the dependency of stimulation of the release on NaF concentration was well correlated with those of NaF-enhanced inositol phosphate formation and increase in cytosolic free Ca2+. Although the effect of NaF on PGE2-induced catecholamine release in the presence of ouabain was additive at concentrations below 20 mM, there was no additive effect at 25 mM NaF. Furthermore, the time course of catecholamine release stimulated by 20 mM NaF in the presence of ouabain was quite similar to that by 1 microM PGE2, and both stimulations were markedly inhibited by amiloride, with half-maximal inhibition at 10 microM. Pretreatment of the cells with pertussis toxin did not prevent, but rather enhanced, PGE2-induced catecholamine release over the range of concentrations examined. These results demonstrate that NaF mimics the effect of PGE2 on catecholamine release from chromaffin cells and suggest that PGE2-evoked catecholamine release may be mediated by the stimulation of phosphoinositide metabolism through a putative GTP-binding protein insensitive to pertussis toxin.     

Optimization of cell culture conditions for production of biologically active proteins

We investigated the basic technology of cell culture conditions for production of useful substances such as cytokines, and related proteins produced by Namalwa cells. Namalwa cells (Klein, 1972), human B lymphoblastoid cells, were used for large scale production of alpha-interferon (Klein, 1979). Namalwa KJM-1, a subline of Namalwa cells, adapted to serum- and albumin-free medium, can grow at a high density above 1 × 10⁷ cells/ml in suspension mode by the use of a perfusion culture system, Biofermenter^?, containing a cone-type cell-sedimentation column as cell separator (Sato, 1983).Several kinds of cytokine cDNA can be introduced and expressed in Namalwa KJM-1 cells (Miyaji, 1990a,b,c). Some of these were produced in large quantities by use of a gene amplification method with dhfr (Miyaji, 1990c), even though the Namalwa KJM-1 cells contained endogenous dhfr genes. For stable production of the target protein, Namalwa KJM-1 cells are very useful host cells, because they have no effective endogenous protease activity in the conditioned medium.Using Biofermenter with micro-silicone fibers and a dialysis system, the specific productivity of the target proteins was not depressed at a high cell density.     

Cancer chemotherapy and somatic cell mutation

The occurrence of a second neoplasm is one of the major obstacles in cancer chemotherapy. The elucidation of the genotoxic effects induced by anti-cancer drugs is considered to be helpful in identifying the degree of cancer risk. Numerous investigations on cancer patients after chemotherapy have demonstrated: (i) an increase in the in vivo somatic cell mutant frequency (Mf) at three genetic loci, including hypoxanthine–guanine phosphoribosyl-transferase (hprt), glycophorin A (GPA), and the T-cell receptor (TCR), and (ii) alterations in the mutational spectra of hprt mutants. However, the time required for and the degree of such changes are quite variable among patients even if they have received the same chemotherapy, suggesting the existence of underlying genetic factor(s). Accordingly, some cancer patients prior to chemotherapy as well as patients with cancer-prone syndrome have been found to show an elevated Mf. Based on the information obtained from somatic cell mutation assays, an individualized chemotherapy should be considered in order to minimize the risk of a second neoplasm.     

UV resonance Raman studies on the activation mechanism of human hematopoietic prostaglandin D2 synthase by a divalent cation, Mg

The Mg²⁺ ion-assisted activation mechanism of the active site Tyr8 of a human hematopoietic prostaglandin D₂ synthase (H-PGDS) was studied by ultraviolet resonance Raman (UVRR) spectroscopy. Addition of Mg²⁺ to the native H-PGDS at pH 8.0 resulted in the Y8a Raman band of Tyr8 shifting from 1615 cm⁻¹ to 1600 cm⁻¹. This large shift to lower energy of the tyrosine Y8a vibrational mode is caused by the deprotonation of the tyrosine phenol group promoted by binding of Mg²⁺. Upon subsequent addition of glutathione (GSH), the Mg²⁺/H-PGDS solution showed the Tyr8 Raman band shifted to 1611 cm⁻¹, which is 11 cm⁻¹ higher than the frequency of the Mg²⁺ complex of H-PGDS, but 4 cm⁻¹ lower than the Mg²⁺ free enzyme. These UVRR observations suggest that the deprotonated Tyr8 in the presence of Mg²⁺ is re-protonated by the abstraction of H⁺ from the thiol group of GSH, and that the re-protonated Tyr8 species forms a hydrogen bond with the thiolate anion of GSH. Density functional theory calculations on several model complexes of p-cresol were also performed, which suggested that the pK_a and vibrational frequencies of the Tyr8 phenol group are affected by the degree and structure of hydration of the Tyr8 residue.     

Ethical Responsibility for the Social Production of Tuberculosis

Approximately one in two hundred persons in the Marshall Islands have active tuberculosis (TB). We examine the historical antecedents of this situation in order to assign ethical responsibility for the present situation. Examining the antecedents in terms of Galtung’s dialectic of personal versus structural violence, we can identify instances in the history of the Marshall Islands when individual subjects made decisions (personal violence) with large-scale ecologic, social, and health consequences. The roles of medical experimenters, military commanders, captains of the weapons industry in particular, and industrial capitalism in general (as the cause of global warming) are examined. In that, together with Lewontin, we also identify industrial capitalism as the cause of tuberculosis, we note that the distinction between personal versus structural violence is difficult to maintain. By identifying the cause of the tuberculosis in the Marshall Islands, we also identify what needs be done to treat and prevent it.     

Phenotypic Characterization of Adenovirus Type 12 Temperature-Sensitive Mutants in Productive Infection and Transformation

Eleven temperature-sensitive mutants of adenovirus type 12, capable of forming plaques in human cells at 33 C but not at 39.5 C, were isolated from a stock of a wild-type strain after treatment with either nitrous acid or hydroxyl-amine. Complementation tests in doubly infected human cells permitted a tentative assignment of eight of these mutants to six complementation groups. Temperature-shift experiments revealed that one mutant is affected early and most of the other mutants are affected late. Only the early mutant, H12ts505, was temperature sensitive in viral DNA replication. Infectious virions of all the mutants except H12ts505 and two of the late mutants produced at 33 C, appeared to be more heat labile than those of the wild type. Only H12ts505 was temperature sensitive for the establishment of transformation of rat 3Y1 cells. One of the late mutants (H12ts504) had an increased transforming ability at the permissive temperature. Results of temperature-shift transformation experiments suggest that a viral function affected in H12ts505 is required for “initiation” of transformation. Some of the growth properties of H12ts505-transformed cells were also temperature dependent, suggesting that a functional expression of a gene mutated in H12ts505 is required to maintain at least some aspects of the transformed state.     

Oxygenation of cobalt(II) protoporphyrin IX dimethyl ester bound to copolymer of 4-vinylpyridine and styrene

The polymeric cobalt(II) porphyrin complexes were prepared from cobalt(II) protoporphyrin IX dimethyl ester(Co(II)P) and copolymers of 4-vinylpyridine and styrene(PSP), and their binding ability of molecular oxygen was studied in toluene solution. The five- and six-coordinate structure of CoP-PSP complexes were confirmed by esr spectra. The esr parameters for the CoP-PSP complexes were not affected by the molecular weight and the vinylpyridine-unit content of PSP-ligand. The 1:1 dioxygen-Co complex was reversibly formed when the solution of CoP-PSP was exposed to oxygen atmosphere at low temperature. While the visible spectra and esr parameters for the dioxygen complexes of CoP-PSP were the same as those of the CoP-pyridine complex, the equilibrium constant for the oxygen binding increased with the vinylpyridine-unit content of the PSP-ligand. The larger entropy change was observed for the oxygenation in the CoP-PSP system especially, of which the vinylpyridine-unit content was large.     

Higher culture pH is preferable for inclusion body formation of recombinant salmon growth hormone inEsherichia coli

Summary Higher culture pH of 7.6 was shown to be preferable for the inclusion body formation of salmon growth hormone (SGH) inEscherichia coli harboring a recombinant plasmid. High-level formation of SGH inclusion bodies was achieved at 33°C (pH 7.6). Growth inhibition by soluble SGH was also observed.