Functional analysis of macrophage hybridomas. I. Production and initial characterization

A series of macrophage hybridomas were generated by fusion of splenic adherent cells with P388D1 tumor cells. Forty-two cell lines were established, and each was cloned by limiting dilution. Six clones that exemplified the spectrum of macrophage heterogeneity were selected for further analysis. Qualitative and quantitative differences in phenotype and functional activity were noted. Some clones constitutively expressed Ia antigens, whereas others only expressed detectable levels of Ia after lymphokine activation. The level of antigen-presenting activity generally correlated with the level of Ia expression. Furthermore, interclonal differences were noted in the levels of receptor-mediated phagocytosis and IL 1 secretion. Generally, the hybridoma clones maintained stable phenotypic and functional properties during approximately 1 yr of continuous in vitro culture. These cloned hybridoma cell lines represent a useful resource to analyze macrophage biology and to dissect structure and function relationships.

Stereoselectivity of 1-aminocyclopropanecarboxylate malonyltransferase toward stereoisomers of 1-amino-2-ethylcyclopropanecarboxylic acid

A malonyltransferase isolated from mungbean (Vigna radiata L.) hypocotyls catalyzed the malonylation of both 1-aminocyclopropane-1-carboxylic acid (ACC) and D-amino acids. The possibility that ACC was recognized by the enzyme as a D-amino acid was investigated by examining the efficiencies of the four stereoisomers of 1-amino-2-ethylcyclopropane-1-carboxylic acid (AEC) serving as substrates of malonyltransferase and as inhibitors of ACC malonyltransferase. Although all four isomers were malonylated by the enzyme and competitively inhibited the malonylation of ACC to N-malonyl-ACC, (1R,2S)-AEC and (1R,2R)-AEC, both of which have an R-configuration as a D-amino acid, had lower Km and Ki values (0.1 to 0.2 mM) than their enantiomers, (1S,2R)-AEC (Km and Ki values were about 1 mM) and (1S,2S)-AEC (Km and Ki values were higher than 10 mM), which have an S-configuration as an L-amino acid. Similarly, (R)-isovaline (2-amino-2-methylbutanoic acid), which has an R-configuration as a D-amino acid, inhibited more effectively the enzymatic conversion of ACC to malonyl-ACC than did (S)-isovaline, which has an S-configuration as an L-amino acid. In mungbean hypocotyls (1R,2S)-AEC and (1R,2R)-AEC were also more efficiently converted into malonyl conjugates and more efficiently inhibited the conversion of radioactive ACC into malonyl-ACC than their enantiomers, although the differences in efficiency among stereoisomers were smaller in hypocotyls than in enzymatic reactions. These results suggest that ACC is recognized by the enzyme as a D-amino acid.

Metabolism of α-aminoisobutyric acid in mungbean hypocotyls in relation to metabolism of 1-aminocyclopropane-1-carboxylic acid

1-Aminocyclopropane-1-carboxylic acid (ACC) is known to be converted to ethylene and conjugated into N-malonyl-ACC in plant tissues. When α-amino[1-(14)C]isobutyric acid (AIB), a structural analog of ACC, was administered to mungbean (Vigna radiata L.) hypocotyl segments, it was metabolized to (14)CO2 and conjugated to N-malonyl-AIB (MAIB). α-Aminoisobutyric acid inhibited the conversion of ACC to ethylene and also inhibited, to a lesser extent, N-malonylation of ACC and D-amino acids. Although the malonylation of AIB was strongly inhibited by ACC as well as by D-amino acids, the metabolism of AIB to CO2 was inhibited only by ACC but not by D-amino acids. Inhibitors of ACC conversion to ethylene such as anaerobiosis, 2,4-dinitrophenol and Co(2+), similarly inhibited the conversion of AIB to CO2. These results indicate that the malonyalation of AIB to MAIB is intimately related to the malonylation of ACC and D-amino acids, whereas oxidative decarboxylation of AIB is related to the oxidative degradation of ACC to ethylene.

The determination of cocaine and its major metabolite, benzoylecgonine, in postmortem fluids and tissues by computerized gas chromatography/mass spectrometry

An analytical procedure for the simultaneous determination of both cocaine and benzoylecgonine in postmortem fluid and tissue samples has been developed by using computerized gas chromatography/mass spectrometry and gas chromatography using a nitrogen/phosphorus (N/P) detector. Both methods are accurate and sensitive and allow the determination of tissue concentrations of cocaine and benzoylecgonine as low as 0.015 microgram/mL.

Relationship between the malonylation of 1-aminocyclopropane-1-carboxylic acid and D-amino acids in mung-bean hypocotyls

In sections from hypocotyls of dark-grown mung-bean (Vigna radiata L.) seedlings, D-phenylalanine and D-methionine (D-met) inhibited the formation of 1-(malonylamino)cyclopropane-1-carboxylic acid from exogenously administered 1-aminocyclopropane-1-carboxylic acid (ACC), resulting in an increase in free ACC content and stimulation of ethylene production, whereas their L-enantiomers had little or no such effect. When the hypocotyls were administered D-Met, it was mainly metabolized to N-malonylmethionine and N-malonylmethionine sulfoxide, and this malonylation process was inhibited to a greater extent by ACC and D-amino acids (phenylalanine and serine) than by L-amino acids. These results indicate that malonylation of D-amino acids and of ACC are intimately interrelated.

Subcellular site of antispermatogenic effect of gossypol and its possible molecular mechanism of action

This paper reports the results of gossypol effects on the testicular mitochondrial ultrastructures and functions. A hypothesis of mechanism of gossypol action based on our experimental data was postulated. Electron microscopic observations confirmed further our previous studies that the mitochondria of the target germ cells were the most sensitive and the most severely damaged among cellular organelles in response to gossypol. The damages included the swelling, vacuolation, crista depletion, lysis, granular accumulation in matrix and the process of intact mitochondria disintegration. The activity of the mitochondrial marker enzyme, the LDH-X of human spermatozoa, was markedly decreased or suppressed completely after gossypol treatment. The functions of isolated testicular mitochondria determined by Warburg manometric and oxygen electrode polarographic methods indicated that gossypol stimulated respiration but inhibited slightly the oxidative phosphorylation at low concentrations (20-40 microM) in vitro. With the increase in concentration of gossypol, the mitochondrial respiration and phosphorylation decreased obviously, they were completely inhibited at a concentration of 80 microM for oxidative phosphorylation and at about 300 microM for respiration. The degree of uncoupling of phosphorylation appears to be dose-dependent. Similar results were obtained for the testicular mitochondria isolated from rats that had been administered per os gossypol previously (6 mg, 10 mg and 15 mg/day X 21 respectively), in which the P/0 ratio decreased significantly (P less than 0.001) as compared with that of the control group. The distribution of 14C-gossypol in mitochondrial was found to be 2-3 times higher than that in other subcellular fractions. Similar pattern of distribution was shown in double labeling experiments with 14C-gossypol and 3H-ouabain.

Changes in 1-(malonylamino)cyclopropane-1-carboxylic acid content in wilted wheat leaves in relation to their ethylene production rates and 1-aminocyclopropane-1-carboxylic acid content

In excised wheat (Triticum aestivum L.) leaves, water-deficit stress resulted in a rapid increase, followed by a decrease, in ethylene production rates and in the levels of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene. However, the level of N-malonyl-ACC (MACC), the major metabolite of ACC, increased gradually, then leveled off. This increase in MACC was much greater than the decrease in ACC level. The MACC levels were positively correlated with severity of water stress. Once established, the MACC levels did not decrease even after the stressed tissues were rehydrated. Administration of labeled ACC and MACC showed that the conjugation of ACC to MACC was essentially irreversible. Repeated wilting treatments following the first wilting and rehydration cycle resulted in no further increase in ethylene production and in the levels of ACC and MACC. However, when benzyladenine was supplied during the preceding rehydration process, subsequent wilting treatment resulted in a rise in MACC level and a rapid rise followed by a decline in ethylene production rates and in the level of ACC. The magnitude of these increases was, however, smaller in these rewilted tissues than that observed in the first wilting treatment. Since MACC accumulates with water stress and is not appreciably metabolized, the MACC level is a good indicator of the stress history in the detached leaves used.

Phencyclidine concentrations in postmortem body fluids and tissues

Phencyclidine (PCP) concentrations have been studied in the blood and tissues of Los Angeles County victims whose deaths were related to PCP use. In most cases PCP blood concentrations ranged from 0.01 to 0.9 micrograms/mL while higher concentrations were found in the liver, urine, bile, brain, and kidney.

An analysis on the equivalence of the eye to a system with aberration

Computed transfer functions for epsilon = 0.60 and 0.75 annular pupils of 2.67 mm o.d. show that absorption of the average spherical aberration of the eye is still incomplete but if the eye is so designed as to adjust its focal plane in order to achieve a best Strehl ratio, it would show a transfer function approaching that of a diffraction limited system, i.e. the optical defect of the eye is overcompensated. However, it is argued that a varying amount of focusing adjustment of the eye is needed in order to account for the transfer function of the eye of different pupil sizes, though not always to the extent of achieving a best Strehl ratio. Such a property of the eye is referred to variously as the antidefocusing, deblurring or contrast constancy phenomenon and, when operationally defined, this is equivalent to saying that the eye has a greater depth of focus than that defined for a physical system based upon a fixed demodulation criterion. The significance of the physiological depth of the eye is discussed.