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D O Adams

Publications and source records attributed to D O Adams.

At least 127 records · Page 7Linked to original sources
PubMed1980

Effector mechanisms of cytolytically activated macrophages. I. Secretion of neutral proteases and effect of protease inhibitors.

Peritoneal macrophages from C56BL/6J mice, when activated by bacillus Calmette-Guérin, lysed syngeneic MCA-I sarcoma targets but not syngeneic embryo fibroblasts. Inflammatory macrophages elicited by concanavalin A (Con A) did not appreciably lyse either target. The activated macrophages secreted more neutral proteases into the extracellular compartment, both absolutely and relative to intracellular content, than did the Con A inflammatory macrophages. Bovine pancreatic trypsin inhibitor (BPTI) (750 KIU/ml) and diisopropylfluorophosphate (2 x 10(-3) M) inhibited cytolysis of neoplastic targets by the activated macrophages. The BPTI had to be present during the 48-hr macrophage-tumor cell interaction to reduce cytolysis; pretreatment of either the macrophages or the targets by the BPTI did not reduce cytolysis. The inhibitors, at the concentrations found to inhibit cytolysis, were not toxic to the macrophages as judged by morphology, by the ability of the macrophages to incorporate leucine into protein, and by the potential for cytolytic activation of the macrophages in vitro. It is suggested that neutral serine protease(s) secreted by activated macrophages participate in the cytolytic destruction of neoplastic cells.

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PubMed1979

Macrophages.

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Animals↗
PubMed1979

Ethylene biosynthesis: Identification of 1-aminocyclopropane-1-carboxylic acid as an intermediate in the conversion of methionine to ethylene.

L-[U-(14)C]Methionine fed to apple tissue was efficiently converted to ethylene when the tissue was incubated in air. In nitrogen, however, it was not metabolized to ethylene but was instead converted to 1-aminocyclopropane-1-carboxylic acid (ACC). When apple tissues were fed with L-[methyl-(14)C]methionine or L-[(35)S]methionine and incubated in nitrogen, radioactivity was found subsequently in methylthioribose. This suggests that methionine is first converted to S-adenosylmethionine which is in turn fragmented to ACC and methylthioadenosine. Methylthioadenosine is then hydrolyzed to methylthioribose. The conclusion that ACC is an intermediate in the conversion of methionine to ethylene is based on the following observations: Labeled ACC was efficiently converted to ethylene by apple tissue incubated in air; the conversion of labeled methionine to ethylene was greatly decreased in the presence of unlabeled ACC, but the conversion of labeled ACC to ethylene was little affected by the presence of unlabeled methionine; and 2-amino-4-(2'-aminoethoxy)trans-3-butenoic acid, a potent inhibitor of pyridoxal phosphate-mediated enzyme reactions, greatly inhibited the conversion of methionine to ethylene but did not inhibit conversion of ACC to ethylene. These data indicate the following sequence for the pathway of ethylene biosynthesis in apple tissue: methionine --> S-adenosylmethionine --> ACC --> ethylene. A possible mechanism accounting for these reactions is presented.

Journal Article↗
PubMed1979

Regulation of Auxin-induced Ethylene Production in Mung Bean Hypocotyls: Role of 1-Aminocyclopropane-1-Carboxylic Acid.

Ethylene production in mung bean hypocotyls was greatly increased by treatment with 1-aminocyclopropane-1-carboxylic acid (ACC), which was utilized as the ethylene precursor. Unlike auxin-stimulated ethylene production, ACC-dependent ethylene production was not inhibited by aminoethoxyvinylglycine, which is known to inhibit the conversion of S-adenosylmethionine to ACC. While the conversion of methionine to ethylene requires induction by auxin, the conversion of methionine to S-adenosylmethionine and the conversion of ACC to ethylene do not. It is proposed that the conversion of S-adenosylmethionine to ACC is the rate-limiting step in the biosynthesis of ethylene, and that auxin stimulates ethylene production by inducing the synthesis of the enzyme involved in this reaction.

Journal Article↗
PubMed1979

Preparative techniques for freezing and freeze-sectioning macrophages for energy dispersive x-ray microanalysis.

In order to study the subcellular distribution of normal intracellular electrolytes and of metal pollutants, rabbit alveolar macrophages and mouse peritoneal macrophages were maintained in standard tissue culture medium with or without various concentrations of cadmium chloride or ammonium vanadate. A variety of preparative techniques were employed to study both monolayers and cell pellets by light microscopy, transmission electron microscopy, scanning electron microscopy and energy-dispersive x-ray microanalysis. Pellets of macrophages centrifuged in narrow bore centrifuge tubes were successfully snap-frozen in liquid-nitrogen-cooled liquid propane and either sectioned on a cryoultramicrotome or freeze-substituted with 1% osmium tetroxide in acetone and embedded in Epon. Spot probes of freeze-dried, frozen thin sections for normal intracellular electrolytes such as potassium, phosphorus and sulfur showed good localization to the cells and differences between organelles. Monolayers were freeze-dried and directly embedded in Epon. When Epon thin sections of these cells and of the freeze-substituted, Epon embedded pellets were obtained with a dry knife, intracellular electrolytes such as potassium, phosphorus and cadmium could still be detected by energy-dispersive x-ray microanalysis. It is concluded that in studies using snap-freezing for element localization, maximum information is obtained with the simultaneous application of a combination of preparatory techniques.

Animals↗
PubMed1978

A simple, sensitive assay for determining DNA in mononuclear phagocytes and other leukocytes.

An assay for determining the DNA content of mononuclear phagocytes is described. The assay is efficient and very sensitive, measuring as little as 1 microgram of DNA. Content of DNA is a linear function of the number of mononuclear phagocytes in the sample. One million murine macrophages contain 10.1 +/- 0.36 microgram of DNA. Consequently, samples of as few as 100,000 macrophages can be accurately quantified to be related to other biochemical analyses.

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PubMed1977

Methionine metabolism in apple tissue: implication of s-adenosylmethionine as an intermediate in the conversion of methionine to ethylene.

If S-adenosylmethionine (SAM) is the direct precursor of ethylene as previously proposed, it is expected that 5'-S-methyl-5'-thioadenosine (MTA) would be the fragment nucleoside. When [Me-(14)C] or [(35)S]methionine was fed to climacteric apple (Malus sylvestris Mill) tissue, radioactive 5-S-methyl-5-thioribose (MTR) was identified as the predominant product and MTA as a minor one. When the conversion of methionine into ethylene was inhibited by (l)-2-amino-4-(2'-aminoethoxy)-trans-3-butenoic acid, the conversion of [(35)S] or [Me(14)C]methionine into MTR was similarly inhibited. Furthermore, the formation of MTA and MTR from [(35)S]methionine was observed only in climacteric tissue which produced ethylene and actively converted methionine to ethylene but not in preclimacteric tissue which did not produce ethylene or convert methionine to ethylene. These observations suggest that the conversion of methionine into MTA and MTR is closely related to ethylene biosynthesis and provide indirect evidence that SAM may be an intermediate in the conversion of methionine to ethylene.When [(35)S]MTA was fed to climacteric or preclimacteric apple tissue, radioactivity was efficiently incorporated into MTR and methionine. However, when [(35)S]MTR was administered, radioactivity was efficiently incorporated into methionine but not MTA. This suggests that the sulfur of MTA is incorporated into methionine via MTR. A dual label experiment with [(35)S, Me-(3)H]MTA indicates that the CH(3)S group of MTA was transferred as a unit to form methionine.A scheme is presented for the production of ethylene from methionine, the first step being the activation of methionine by ATP to give SAM. SAM is fragmented to give ethylene, MTA, and other products. MTA is then hydrolyzed to MTR which donates its methylthio group to a four-carbon acceptor to reform methionine.

Journal Article↗
PubMed1977

The structure of mononuclear phagocytes differentiating in vivo. III. The effect of particulate foreign substances.

The response of mononuclear phagocytes to three inert particles--barium sulfate, talc, and thorium dioxide--was studied by correlated light and electron microscopy. All three particles induced maturation of the mononuclear phagocytes, which proceeded to the stage of the mature macrophage and required 7 to 9 days. Once established, maturation persisted as long as 45 days, as did the inert particles. The resultant lesions, dense aggregates of mature macrophages, were termed mature granulomas. The resultant maturation differed from that produced by digestible bacteria in tempo and extent but not in pattern.

Animals↗
PubMed1976

Cellular immunity in rats with primary brain tumors: inhibition of macrophage migration by soluble extracts of avian sarcoma virus-induced tumors.

Rats bearing primary tumors of the brain induced by avian sarcoma virus (ASV) were studied with the migration-inhibition factor (MIF) assay for the presence of cell-mediated immunity to tumor-associated antigens. Astrocytomas and sarcomas of the brain were induced in 34 neonatal F344 rats by the intracerebral inoculation of Bratislava-77 ASV. At weekly intervals from 4 to 9 weeks after the inoculation with virus, peritoneal exudate cells (PEC) from rats bearing brain tumors were tested an an MIF assay against soluble and KCl-treated extracts of a syngeneic, ASV-induced sarcoma. Incubation of the PEC with a soluble extract of syngeneic liver or with a KCl extract of a syngeneic, chemically induced tumor served as controls. Of 14 rats tested against the soluble tumor extract, 6 (43%) had statistically significant inhibition of migration (P less than or equal to 0.05). Of 23 animals tested against the KCl extract, 16 (70%) had significant inhibition. Immunity to the KCl extract was significant in most rats at each period. Ten rats were tested against a KCl extract of a hamster ASV-induced tumor; 7 gad significant inhibition of migration. None of 3 tested against a soluble extract of a syngeneic, chemically induced tumor had significant inhibition. Rats bearing ASV-induced brain tumors displayed cell-mediated immunity to tumor-associated antigen or antigens of ASV-induced tumors, which could be solubilized.

Animals↗
PubMed1975

The structure of mononuclear phagocytes differentiating in vivo. II. The effect of Mycobacterium tuberculosis.

The development and resolution of granulomas induced by Mycobacterium tuberculosis were sequentially traced by correlated light and electron microscopy. The scattered, immature monocytes initially composing the lesions evolved by orderly steps into coalescent, well developed macrophages and ultimately into swirling nests of highly complex epithelioid cells. These ultrastructural changes represent differentiation in vivo of the mononuclear phagocytes. The number of mycobacteria present than waned markedly, and the epithelioid granulomas developed into foreign body granulomas and finally into simple chronic inflammation. Concmonitantly, the epithelioid cells evolved into macrophages and ultimately into immature, monocyte-like forms. These observations suggest that the development of a granuloma represents differntiation in vivo of the constituent mononuclear phagocytes in response to an evoking stimulus. From comparisons with previous studies, mononuclear differentiation in vivo appears to have a fixed pattern and a markedly alterable pace. The observations also suggest a previously undescribed fate for mononuclear phagocytes in developing granulomas. As the granuloma-evoking agent is destroyed, the highly differentiated mononuclear phagocytes change into less mature forms.

Animals↗
PubMed1974

The structure of mononuclear phagocytes differentiating in vivo. I. Sequential fine and histologic studies of the effect of Bacillus Calmette-Guerin (BCG).

Although the differentiation of mononuclear phagocytes is fundamental to their multifarious activities, their differentiation is incompletely understood-particularly in vivo. The development of an epithelioid granuloma may be hypothesized to represent such differentiation in vivo. To test this, the sequential ultrastructure of developing epithelioid granulomas was examined. Viable bacilli Calmette-Guerin (BCG) injected into the subcutaneum of guinea pigs produced epithelioid granulomatous inflammation, which was sampled for light and electron microscopy on alternate days until the 33rd day after injection. Initially, monocytes invaded the tissues and then coalesced, enlarged and formed small granulomas which ultimately evolved into epithelioid granulomas. The monocytes, ultrastructurally very simple cells, developed increased nuclear euchromatin, prominent nucleoli, extensive cytoplasm, free ribosomes, abundant Golgi profiles, many mitochondria and numerous large lysosomes and became macrophages. The macrophages in turn underwent further enlargement and became closely intertwined with one another to form epithelioid cells-large polygonal macrophages, containing euchromatic nuclei, numerous lysosomes, plentiful mitochondria and prominent synthetic apparatus. These changes undergone by monocytes during their development into epithelioid cells, which may be divided into five stages, are interpreted as differentiation in vivo of the mononuclear phagocytes. The observations demonstrate directly the differentiation of these cells in vivo and suggest some, if not all, characteristic features of granulomatous inflammation result from such differentiation.

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