Nonspecific inhibition of tumor growth in vivo by admixed allogeneic tumor-sensitized lymphoid cells and identical inactivated allogeneic tumor cells.

With the in vivo tumor neutralization test (Winn test), growth of a transplanted (KMT-17) from Wistar-King-Aptekman rats was inhibited by allogeneic tumor (AH-66 from Donryu rats)-sensitized syngeneic lymphoid cells admixed with mitomycin C (MMC)-treated AH-66 cells. The observed tumor inhibition may be immunologically nonspecific, since no cross-antigens were detected by membrane immunofluorescence on the surfaces of KMT-17 and AH-66 cells. Close contact among KMT-17, AH-66-sensitized lymphoid cells and MMC-treated AH-66 cells was required for the inhibition of KMT-17 growth. AH-66 cells pretreated with formalin or ultrasonication lost tumor inhibitory activity when they were admixed with AH-66-sensitized lymphoid cells, and only MMC-treatment effectively preserved the tumor inhibitory activity of AH-66 cells. The sensitized spleen cells, draining lymph node, or peripheral blood cells inhibited tumor growth when they were admixed with MMC-treated AH-66 cells, whereas nucleated cells from bone marrow, thymus, or distal lymph node did not. Growths of KMT-17 were inhibited by admixed sensitized spleen cells and MMC-treated AH-66 even when pre-irradiated rats were used as recipients.     

Inhibition of dimeric dihydrodiol dehydrogenase by 4-hydroxyphenylketone derivatives: aspects of inhibitor structure and binding specificity.

Dimeric dihydrodiol dehydrogenases from pig liver, monkey kidney, and rabbit lens were inhibited more potently by 4-hydroxyphenylketones such as 4-hydroxybenzaldehyde, 4-hydroxyphenylglyoxal, and 4-hydroxyacetophenone than by isoascorbate and ascorbate, known inhibitors of the enzymes. No significant inhibition was observed with 2- or 3-hydroxyphenylketones, phenylketones with a functional group other than a hydroxy group at the 4-position, and 4-hydroxyphenyl derivatives without a carbonyl group. The steady-state kinetic analyses of the inhibition of the pig liver enzyme indicated that the 4-hydroxyphenylketones, similarly to ascorbate and its epimer, bound to an enzyme-NADP+ binary complex as competitive inhibitors with respect to dihydrodiol substrate. The inhibition by the 4-hydroxyphenylketones was uncompetitive with respect to isoascorbate, and the addition of one of the 4-hydroxyphenylketones or isoascorbate with NADP+ afforded a great protective effect against inactivation of the enzyme by diethylpyrocarbonate or by heat treatment, which indicates that 4-hydroxyphenylketones and isoascorbate bind at the same site in or near the active center of the enzyme. The structural comparison of 4-hydroxybenzaldehyde and ascorbate suggests that the hydroxy group at C-5, carbonyl group at C-1 and lactone ring of ascorbate are important for the binding to the enzyme.     

Effects of Different Levels of Intraocular Stray Light on Kinetic Perimetry Findings

PurposeTo evaluate the effect of different levels of intraocular stray light on kinetic perimetry findings.MethodsTwenty-five eyes of 25 healthy young participants were examined by automated kinetic perimetry (Octopus 900) using Goldmann stimuli III4e, I4e, I3e, I2e, and I1e. Each stimulus was presented with a velocity of 3°/s at 24 meridians with 15° intervals. Four levels of intraocular stray light were induced using non-white opacity filter (WOF) filters and WOFs applied to the clear plastic eye covers of the participants. The visual acuity, pupil diameter, isopter area, and kinetic sensitivity of each meridian were analyzed for each WOF density.ResultsVisual acuity deteriorated with increasing WOF densities (p < 0.01). With a visual acuity of 0.1 LogMAR units, the isopter areas for III4e, I4e, I3e, I2e, and I1e decreased by -32.7 degree² (-0.2%), -255.7 degree² (-2.6%), -381.2 degree² (-6.2%), -314.8 degree² (-12.8%), and -59.2 degree² (-15.2%), respectively; kinetic sensitivity for those stimuli decreased by -0.1 degree (-0.1%), -0.8 degree (-1.4%), -1.6 degree (-3.7%), -2.7 degree (-9.7%), and -1.7 degree (-16.2%), respectively. The pupil diameter with each WOF density was not significantly different.ConclusionKinetic perimetry measurements with a high-intensity stimulus (i.e., III4e) were unaffected by intraocular stray light. In contrast, measurements with the I4e, I3e, I2e, and I1e stimuli, especially I2e and I1e, were affected. Changes in the shape of the isopter resulting from opacity must be monitored, especially in cases of smaller and lower-intensity stimuli.     

Correction to: River to river: First evidence of eel movement between distant rivers via the sea

Environmental Biology of Fishes - A Correction to this paper has been published: https://doi.org/10.1007/s10641-021-01108-5     

1H NMR studies of substrate hydrogen exchange reactions catalyzed by L-methionine gamma-lyase

Hydrogen exchange reactions of various L-amino acids catalyzed by L-methionine gamma-lyase (EC 4.4.1.11) have been studied. The enzyme catalyzes the rapid exchange of the alpha- and beta-hydrogens of L-methionine and S-methyl-L-cysteine with deuterium from the solvent. The rate of alpha-hydrogen exchange was about 40 times faster than that of the enzymatic elimination reaction of the sulfur-containing amino acids. The enzyme also catalyzes the exchange reaction of alpha- and beta-hydrogens of the following straight-chain L-amino acids which are not susceptible to elimination: norleucine, norvaline, alpha-aminobutyrate, and alanine. The exchange rates of the alpha-hydrogen and the total beta-hydrogens of L-alanine and L-alpha-aminobutyrate with deuterium followed first-order kinetics. For L-norvaline, L-norleucine, S-methyl-L-cysteine, and L-methionine, the rate of alpha-hydrogen exchange followed first-order kinetics, but the rate of total beta-hydrogen exchange decreased due to a primary isotope effect at the alpha-position. One beta-hydrogen of S-methyl-L-cysteine was exchanged faster than the other, although both the beta-hydrogens were exchanged completely with deuterium ultimately. L-Phenylalanine and L-tryptophan slowly underwent alpha-hydrogen exchange. The pro-R hydrogen of glycine was deuterated stereospecifically. None of the following amino acids were susceptible to the enzymatic hydrogen exchange: D isomers of the above amino acids, branched chain L-amino acids, acidic L-amino acids, and basic L-amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Complete nucleotide and derived amino acid sequences of the fourth component of mouse complement (C4). Evolutionary aspects

The nucleotide sequence coding for the fourth component of mouse complement (C4) has been determined from a cloned genomic DNA fragment and a cloned cDNA fragment. The amino acid sequence of the protein was deduced. The single chain precursor protein (pro-C4) consists of 1719 amino acid residues. The mature beta, alpha, and gamma subunits contain 654, 766, and 291 amino acids, respectively. One potential carbohydrate attachment site is predicted for the beta chain, three for the alpha chain, and none for the gamma chain. From a comparison with human C4 cDNA sequence an extensive overall sequence homology, 79% in nucleotides and 76% in amino acids, is observed. There is conservation in both the position and number of cysteine residues in human and mouse C4. We compared the mouse C4 amino acid sequences with those of mouse C3 and human alpha 2-macroglobulin and the evolutionary relationship among these three proteins is discussed.     

Flow cytometry to identify cell types to which enzymes bind. Effect of lactic dehydrogenase virus on enzyme binding

Flow cytometry was used to measure the binding of enzymes (i.e. lactate dehydrogenases 1 and 5, malate dehydrogenase, and asparaginase) to cells. Of the four enzymes studied, asparaginase showed the greatest binding. Single color analysis revealed that asparaginase bound best to preparations enriched in macrophages, and dual color analysis showed that the binding was to macrophages. Studies on continuous cell lines revealed that asparaginase bound to one mouse macrophage line, but not to another or to murine fibroblasts. Inoculation of mice with lactic dehydrogenase virus, a virus that infects macrophages, decreased the in vivo clearance of asparaginase from the circulation and the in vitro binding of asparaginase to peritoneal macrophages. It is concluded that flow cytometry can be used to study the binding of enzymes to cells, to identify the cell type to which the enzyme binds, and to measure changes in the capacity of cells to bind enzymes.