Accelerated calcium ion uptake in murine thymocytes induced by concanavalin A.

The mechanism of enhancement of Ca2+ uptake by the T cell mitogen concanavalin A (Con A) was studied in murine thymocytes. Native Con A enhanced the rate of Ca2+ uptake as much as 9-fold, an increase being observed within five minutes after Con A addition. The effect of Con A was reversed completely by alpha-methyl mannopyranoside (alpha-MM). Increased Ca2+ uptake was observed with increasing concentrations of Con A, between 2 and 400 microgram/ml, indicating that the stimulation of Ca2+ uptake is not restricted to mitogenic lectin concentrations (0.5-2 microgram/ml). Succinyl Con A exhibits only a slight effect in the same concentration ranges as native Con A. Ca2+ uptake, both in the absence and presence of Con A, is strongly dependent on energy metabolism and is carrier mediated. The augmentation of Ca2+ uptake by native Con A is due to an enhanced Vmax. Uptake of the anion, CrO42-, by thymocytes, found to be a non-saturable process, was also enhanced by Con A. The effect of Con A on CrO42- permeability appears to be independent of its effect on Ca2+ uptake.     

Human cytomegalovirus genome: partial denaturation map and organization of genome sequences.

Contour-length measurements of both nondenatured and partially denatured DNA from purified extracellular human cytomegalovirus indicate that more than one size class of viral DNA is encapsidated. In addition to a size class averaging about 100 x 10(6) daltons, a much less abundant class of larger viral DNA molecules, 150 x 10(6) to 155 x 10(6) daltons, was extracted from purified extracellular virus. As predicted by melting-curve analysis, partial denaturation of human cytomegalovirus DNA generates denaturation maps showing distinctive adenine plus thymidine (A+T)-rich and guanine plus cytosine (G+C)-rich localizations. Alignment of partial denaturation maps of both 100 x 10(6)- and 150 x 10(6)- to 155 x 10(6)-dalton molecules from maximum overlap of common A+T- and G+C-rich zones clearly shows six unique zones contained in a length equal to the longest class, 150 x 10(6) to 155 x 10(6) daltons. However, various alignments of the smaller class of the molecules within the confines of the approximately 100 x 10(6)-dalton-length equivalent are nondistinctive. Of the six unique A+T- and G+C-rich zones, five are linked in a specific sequence and maintain the same relative orientation; these features indicate the absence of major inversions within these zones. The sixth unique zone may occur at either end of this five-zone series, but it was never found at both ends of the same molecule. Additionally, this terminal zone appears to undergo complete inversions at least at one end of the alignment, and perhaps at both. These data indicate that 150 x 10(6)- to 155 x 10(6)-dalton molecules comprise human cytomegalovirus-specific genetic information.     

Stimulation of Cellular Thymidine Kinases by Human Cytomegalovirus

Thymidine kinase (TK) activity in WI-38 and MRC-5 human fibroblasts was analyzed by discontinuous polyacrylamide gel electrophoresis (disc-PAGE) and discontinuous glycerol gradient electrophoresis (disc-GEP) after subculture or human cytomegalovirus (HCMV) infection. Two peaks of TK activity with different relative fraction-of-migration (R(f)) values were resolved by disc-PAGE or disc-GEP in extracts from log-phase and infected cells. Growing WI-38 cells expressed a slowly migrating (R(f) = 0.14 PAGE, R(f) = 0.4 GEP) peak of TK activity, which was partially inhibited by 1.0 mM dCTP, but which retained little activity at pH 4.5. Growing MRC cells also displayed a slowly migrating peak (R(f) = 0.10 PAGE) with similar properties. Both cell types expressed a faster-migrating TK activity (R(f) = 0.45 PAGE, R(f) = 0.7 GEP) in the growing and resting state that was strongly inhibited by 1 mM dCTP but retained 50% activity at pH 4.5. When either cell type was infected with HCMV, there was a rapid and high-level stimulation of the slowly migrating form of TK and a slight stimulation of the faster-migrating form. Two strains of HCMV (AD169 and Town) failed to produce an electrophoretically distinct virus TK in either cell type after infection. TK enzymes were partially purified by disc-GEP from extracts of log-phase WI-38 or AD169-infected WI-38 cells. Characterization of these enzymes with respect to phosphate donor specificity, pH optima, thermostability, and salt inhibition showed the HCMV-stimulated TKs to be of cellular origin.     

Hyperphagia and hyperdipsia after locus coeruleus lesions in the stumptailed monkey.

Bilateral lesions of the nucleus locus coeruleus in 7 female stumptail monkeys were followed by long lasting hyperphagia and hyperdipsia. The percentage increase in weight at five weeks after lesioning correlated highly with 3-methoxy-4-hydroxy-phenethylene glycol (MHPG) concentration in the cerebral cortex. This relationship suggests that the effects are due to the locus coeruleus system and are not the result of variable destruction of the ventral noradrenergic or adjacent non-noradrenergic pathways.     

Characterization of the DNA of a Nonoccluded Baculovirus, Hz-1V

The DNA of the nonoccluded baculovirus (Hz-1V) obtained from the IMC-Hz-1 cell line was characterized by physicochemical and restriction endonuclease techniques. Hz-1V DNA isolated from purified virus had buoyant densities of 1.58 and 1.54 g/ml in CsCl-ethidium bromide density gradients, which corresponded to supercoiled and to relaxed circular and linear DNA, respectively. Neutral CsCl equilibrium centrifugation indicated that the Hz-1V DNA had a buoyant density of 1.7024 g/ml, which corresponded to a guanine-plus-cytosine (G+C) content of 43%. Thermal denaturation indicated a high G+C domain(s) in the Hz-1V genomic DNA. The domain(s), which included about 11% of the total genomic DNA, exhibited a T(m) of 97 degrees C. The remaining portion (89%) of the DNA had a T(m) of 86.5 degrees C. The T(m)s corresponded to G+C contents of 42 and 67%, respectively. The mean genetic complexity of Hz-1V DNA determined by DNA reassociation kinetic analysis was found to be 152 x 10(6). A possible rapidly reassociating component comprising approximately 13% of the genome was observed. The mean molecular weights from restriction endonuclease digests were 159 x 10(6) for both HindIII and EcoRI. Genomic heterogeneity was found in both the wild-type Hz-1V stock and in two plaque isolates. Of 12 single-plaque isolates, 3 basic restriction endonuclease DNA fragment patterns were observed. The molecular size estimates from electron microscopic contour lengths of uncloned viral DNA ranged from 70 to 158 megadaltons, and the mode was the 130- to 140-megadalton class.     

(+)-Arctigenin,a lignan from Wikstroemia indica

A new lignan, (+)-aretigenin has been isolated from the roots of Wikstroemia indica (Nan-Ling-Jao-Hua) and identified as 8(R) 8′(S)-4′-hydroxy-3, 4,3′-trimethoxylignan-olid (9, 9′) on the basis of spectral evidence as well as a direct comparison with its enantiomer, (?)-arctigenin.     

Differentiation of aflatoxins from territrems.

Three methods were adopted for differentiation of aflatoxins B1 and B2 from territrems A and B. They were as follows. (i) Then-layer chromatography coupled with chemical confirmation. A significant decrease in the Rf value of trifluoroacetic acid-treated aflatoxin B1 developed in chloroform-acetone (85:15, vol/vol) was satisfactory in differentiating this toxin from the other three. (ii) High-pressure liquid chromatography monitored synchronously at two wavelengths, 365 and 335 nm. The ratio derived from this double-wavelengh detection could serve as an indicator of the presence of each toxin. (iii) Velasco's flurotoxin meter method, which is used for the determination of aflatoxins within the range of 0 to 50 ng/ml, was not significantly affected by territrems even when they were present in quantities at the microgram-per-milliliter level.     

Microwave treatment of intracerebral l1210 leukemia: Schedule-dependent partial reversal of the effects of methotrexate

One-GHz microwave (MW) irradiation at a power density of 5 mW/cm² was combined with methotrexate (MTX) in an attempt to treat more effectively central nervous system (CNS) L1210 leukemia in DBA/2J mice. When mice with CNS leukemia were treated with the combination of MW and MTX, there was no improvement in survival compared with a group of animals treated with MTX alone; however, the group that received MTX before the MW exposure had a significantly reduced survival time compared with the group treated with MTX alone or with the group to which MTX was administered after MW.     

Transport of 5-hydroxytryptamine by dense granules from porcine platelets

A method is described for the isolation of a homogeneous preparation of dense granules from procine platelets. The purified dense granule fraction contained approximately 400 nmol of 5-hydroxytryptamine/mg of protein and appeared to be homogeneous when examined by electron microscopy. Isolated dense granules transport exogenously added 5-hydroxytryptamine via two mechanisms: 1) a carrier-mediated process predominating at low substrate concentrations and 2) a diffusion-controlled process predominating at high substrate concentrations. Temperature studies revealed an apparent energy of activation of 14.9 kcal/mol for the carrier-mediated transport. Kinetic data yielded a Km of 3.3 micron and a Vmax of 0.79 nmol/min/mg of protein for the mediated transport process. Steady state uptake was sensitive to changes in medium osmotic pressure and a decline in uptake below 300 mosM was correlated with release of endogenous 5-hydroxytryptamine. The transport was inhibited by a number of structural analogs of 5-hydroxytryptamine. These results demonstrate the existence of a carrier-mediated transport system for 5-hydroxytryptamine in the membranes of the platelet dense granules.