Growth of measles and subacute sclerosing panencephalitis viruses in human neural cell lines

Growth of cell-free subacute sclerosing panencephalitis (SSPE) virus was compared with that of measles virus in three human neural cell lines; neuroblastoma, oligodendroglioma, and glioblastoma. The Edmonston strain of measles virus replicated in these neural cells as efficiently as in Vero cells. In contrast, the growth of the Mantooth strain of SSPE virus was suppressed moderately in neuroblastoma cells and markedly in oligodendroglioma and glioblastoma cells in spite of the induction of apparent cytopathic effects in these cells. Virus adsorption, defective interfering particles, interferon, and temperature sensitivity were not responsible for this low yield of SSPE virus in neural cell lines. Synthesis of viral proteins of SSPE virus was slower than that of measles virus in oligodendroglioma and glioblastoma cells. These results suggest that the slow rate of synthesis of viral proteins may be relevant to the low yield of SSPE virus in neural cells.     

Studies on recovery mechanism from rinderpest virus infection in rabbits. I. Effect of anti-thymocyte serum and thymectomy.

The role of cell-mediated immunity in recovery from rinderpest virus infection in rabbits was investigated by application of immunosuppressive procedures, i.e., treatment with anti-thymocyte serum and combined treatment with thymectomy and anti-thymocyte serum, both of which were confirmed to depress significantly cell-mediated immunity in rabbits. The immunosuppressed animals recovered in almost the normal fashion in terms of clinical signs, of virus clearance from the blood and lymphoid tissues and of repair of the lesions. It was suggested that the thymus-dependent cell-mediated immunity may not be essential in recovery from rinderpest virus infection. Possibility of participation of other recovery mechanisms was discussed.     

Temporal analysis of cellular cytotoxicity and humoral factors during progession and regression of Rous sarcomas in Japanese quails.

Temporal appearance of cellular cytotoxicity and humoral activities including blocking and arming activities during the entire course of Rous sarcoma development in Japanese quails was examined by microcytotoxicity assay with comparison of animals bearing regressing tumors induced by a moderate dose of virus (regressors) and animals bearing growing tumors induced by a large dose of virus (progressors). Cellular cytotoxicity of the spleen cells in regressors was detected in a biphasic pattern; the first phase being observed as early as 3-5 days post inoculation (p.i.), followed by an eclipse period between 7-10 days p.i. which was the time of active tumor growth, and the second phase occurring after 12 days p.i. when the tumor had attained the maximum size. In progressors, only the first phase was observed. Instead, a stimulatory effect of the spleen cells on growth of target cells was noticed. Arming activity which confers cytotoxic activity on the normal spleen cells was demonstrated in the sera of regressors in the similar biphasic pattern as the cellular cytotoxicity; the early activity being present at 3 days p.i., and the late one after 19 days p.i. The former was detected by pre-incubation of serum with effector cells in microcytotoxicity assay and the latter by pre-incubation with target cells. In progressors, only the early arming activity which reacts with effector cells was demonstrated. Blocking activity which abrogates cellular cytotoxicity was demonstrated in both regressors and progressors but in different patterns of appearance, that is, blocking activity in regressors was only transiently demonstrated only by pre-incubation with effector cells at the time of maximum tumor growth, while the activity in progressors seemed to persist after the tumor reached the maximum size. Since the earlier activity was found to be effective at effector cell level, and the later one at both effector and target cell levels, participation of blocking factors of different types in progressors was also suggested.     

Picosecond Photochemistry of P700-Enriched and Vitamin K1-Depleted Photosystem I Particles Isolated from Spinach

Picosecond transient absorption changes, with a laser intensityas low as one photon absorbed per single reaction center, weremeasured with vitamin K₁-depleted and P700-enriched particleswhich were obtained by ether treatment of spinach PS-I particles.When P700 was in the oxidized state, a bleaching that correspondedto about one-seventh of the ground state absorption was observedjust after a laser flash (0 picosecond delay). A major partof the bleaching decayed with a lifetime of about 35 picoseconds,which corresponds to the relaxation of the excited antenna chl-ato the ground state. By contrast, when P700 was in the reducedstate, the bleaching observed at a 0 ps delay was broader, especiallyon the longer wavelength side than the ground state absorption,probably because of the generation of the excited state of P700.About one half of the bleaching decayed within 35 ps and theremaining half, which had a broad spectrum and a peak around682 nm, was conserved up to 2 ns. This long-lived bleachingprobes no picosecond decay of the radical pair P700⁺-A₀^–because electrons were not transferred from A₀¹ to A₁ in vitaminK₁-depleted particles. After addition of vitamin K₃, an analogof vitamin K₁, to the reduced particles, the bleaching around685 nm decayed successively with an apparent rate of about 150picosecond, while the bleaching around 700 nm was conservedfor up to 2 nanosecond. Thus, the bleaching remaining at 2 nsresembled the difference spectrum of P700, suggesting a subnanosecondquenching of A₀¹ by the externally added vitamin K₃. These observationssupport a recent proposal that the secondary electron acceptorA₁, in photosystem I, is vitamin K₁. ³Permanent address: Optics Laboratory, Korea Standards ResearchInstitute, Daedok Science Town, Chungnam 300-31, Korea. (Received October 24, 1988; Accepted April 14, 1989)     

Monoclonal antibodies specific to a Ca2(+)-bound form of lipocortin I distinguish its Ca2(+)-dependent phospholipid-binding ability from its ability to inhibit phospholipase A2.

Lipocortin I, a Ca2(+)-and phospholipid-binding protein without EF-hand structures, has many biological effects in vitro. Its actual role in vivo, however is unknown. We obtained and characterized five monoclonal antibodies to lipocortin I. Two of these monoclonal antibodies (L2 and L4-MAbs) reacted with the Ca(+)-bound form of lipocortin I, but not with the Ca2(+)-free form, both in vivo and in vitro. Lipocortin I required greater than or equal to 10 microM-Ca2+ to bind the two antibodies, and this Ca2+ requirement was not affected by phosphatidylserine. L2-MAb abolished the phospholipase A2 inhibitory activity of lipocortin I and inhibited its binding to Escherichia coli membranes and to phosphatidylserine in vitro. L4-MAb abolished the phospholipase A2 inhibitory activity of lipocortin I, but did not affect its binding to E. coli membranes or to phosphatidylserine. These findings indicated that the inhibition of phospholipase A2 by lipocortin I was not simply due to removal or capping of the substrates in E. coli membranes. Furthermore, an immunofluorescence study using L2-MAb showed the actual existence of Ca2(+)-bound form of lipocortin I in vivo.     

Assignment of the apolipoprotein A-I gene to 11q23 based on RFLP in a case with a partial deletion of chromosome 11, del(11)(q23.3→qter)

Summary The XmnI genotype at the apolipoprotein A-I locus was heterozygous in a boy with partial deletion of the long arm of chromosome 11, del(11)(q23.3qter). The apolipoprotein A-I gene, previously assigned to chromosome region 11q23q24, has been more specifically localized to 11q23 by excluding the region 11q24qter.     

Protective effect of monoclonal antibodies on lethal mouse hepatitis virus infection in mice.

Neutralizing and nonneutralizing monoclonal antibodies to the peplomer glycoprotein and nucleocapsid protein of a mouse hepatitis virus (MHV), MHV-NuU, protected mice against lethal MHV-2 challenge. Histopathologically, livers of mice receiving protective antibodies showed some focal necrotic lesions with remarkable cellular infiltration instead of fulminant hepatitis caused by MHV-2.     

Effects of adenine nucleotides on the Ca2+-gated cation channel in sarcoplasmic reticulum vesicles

The effects of nucleotides on the Ca2+-gated cation channel in sarcoplasmic reticulum (SR) vesicles were studied by measuring choline influx. The choline influx was measured by following the change in scattered light intensity using the stopped flow technique. ATP enhanced the Ca2+-induced choline influx. The activation followed a single-site titration curve with a dissociation constant of 1.0 +/- 0.5 mM, independent of the Ca2+ concentration. ATP seems to increase the pore radius or number of channels without affecting the gating mechanism of the Ca2+-gated cation channel. ADP, AMP, and adenine enhanced the choline transport in a manner similar to ATP, but cAMP, ITP, UTP, CTP, and GTP did not. The apparent dissociation constants and the maximal activations were as follows: ATP 1.0 mM, 28-fold; ADP 0.9 mM, 18-fold; AMP 0.6 mM, 7-fold, and adenine 0.4 mM, 4-fold. Adenine and AMP behaved as a competitive inhibitor for the activation by ATP. These results are consistent with the Ca2+-induced Ca2+ release observed in skinned muscle fiber and isolated SR.     

Diurnal K+ and Anion Transport in Phaseolus Pulvinus

Diurnal movement of Phaseolus leaf is caused by deformationof the laminar pulvinus located at the joint of the leaf bladeand the petiole. The plants were cultured in solutions withvarious ion compositions, and changes of K⁺, Na⁺, Ca²⁺, Mg²⁺,Cl^–, NO₃– and P₁ concentrations both in the upperand lower parts of the laminar pulvinus were measured. Culturein 10 mM KCl solution caused an increase in K⁺ and Cl^–concentrations both in the upper and lower parts without anysignificant change in the concentration of NO₃^–; culturein 10 mM KNO₃ solution caused an increase in K⁺ and NO₃^–concentration without any significant change in the concentrationof Cl^–; and culture in 10 mM KH₂PO₄ solution caused anincrease in K⁺ and P₁ concentrations without any significantchange in the concentrations of NO₃- and Cl^–. K⁺ moved from the upper to lower parts or from the lower toupper parts diurnally in all plants cultured in any solutionmentioned above. The main inorganic anion that accompanied thisK⁺ movement was Cl^– in KCl solution, and NO₃^– inKNO₃ solution. When the seedlings were cultured in distilledwater or in KH₂PO₄ solution, neither Cl^– NO₃^– norP₁ accompanied this K⁺ movement. In these cases, mainly H⁺ and/ororganic anions are supposed to move in exchange for and/or incombination with K⁺ movement. (Received November 8, 1982; Accepted June 13, 1983)