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Biomedical subjects

J W Moulder

Publications and source records attributed to J W Moulder.

35 records · Page 2Linked to original sources
PubMed1978

Loss of inorganic ions from host cells infected with Chlamydia psittaci.

Mouse fibroblasts (L cells) infected with the 6BC strain of Chlamydia psittaci released potassium ion (K(+)) into the extracellular milieu in a way that depended on size of inoculum and time after infection. When the multiplicity of infection was 500 to 1,000 50% infectious units (ID(50)) per L cell, loss of intracellular K(+) was first apparent 4 to 10 h after infection and was nearly complete at 6 to 20 h. Magnesium ion and inorganic phosphate (P(i)) were also released. Similar multiplicities of ultraviolet-inactivated C. psittaci also caused release of K(+). Leakage of inorganic ions probably resulted from immediate damage to the host-cell plasma membrane during ingestion of large numbers of chlamydiae. With multiplicities of 1 to 50 ID(50) per L cell, ingestion of C. psittaci was not by itself enough to cause release of K(+) and P(i) from infected L cells. There was a delay of 36 to 72 h between infection and massive leakage of intracellular ions during which time the chlamydiae multiplied extensively. Fifty ID(50) of ultraviolet-inactivated C. psittaci per L cell did not bring about significant leakage of K(+), even after 72 h. The mechanism whereby these multiplicities of infection destroy the ability of host cells to retain intracellular molecules is not known. HeLa 229 cells also released K(+) and P(i) after infection, but these losses occurred more slowly than in comparably infected L cells, possibly because C. psittaci did not multiply as extensively in HeLa cells as it did in L cells. The significance of the inability of chlamydiae-infected cells to regulate the flow of molecules through their plasma membranes is discussed.

Cell Membrane Permeability↗
PubMed1977

Toxicity of low and moderate multiplicities of Chlamydia psittaci for mouse fibroblasts (L cells).

When mouse fibroblasts (L cells) were infected in suspension or in monolayer with 10 to 100 50% infectious doses (ID(50)) of Chlamydia psittaci (6BC) per host cell, they showed signs of damage 24 to 48 h later. Host-cell injuries were termed multiplication dependent when both the ingestion and subsequent reproduction of C. psittaci were required; when only ingestion but not replication was needed, the injuries were considered to be multiplication independent. The time that the injury was first apparent, as well as its final magnitude, was proportional to the multiplicity of infection. When L cells ingested infectious or ultraviolet-inactivated C. psittaci, damage was manifested by failure to exclude trypan blue, by leakage of lactic dehydrogenase, by inhibition of reproduction as measured by ability to form colonies, by inhibition of protein and deoxyribonucleic acid synthesis, and eventually by cell disintegration. Infectious, but not ultraviolet-killed, chlamydiae stimulated host-cell glycolysis. Heat-killed chlamydiae were without measurable toxicity. The time of appearance of host-cell injury was always earlier, and its terminal magnitude always greater, with infectious inocula than with ultraviolet-inactivated ones. The multiplication-independent toxicity of ultraviolet-killed C. psittaci disappeared with inocula of less than 10 ID(50) per L cell, but an inoculum of only a single ID(50) of infectious chlamydiae per host cell injured most of the cells it infected, as evidenced by increased trypan blue staining and decreased efficiency of colony formation. The toxicity of multiplicities of infection between 10 and 100 ID(50) of infectious C. psittaci per host cell was the sum of both multiplication-dependent and -independent components. The effects of chloramphenicol and isoleucine deficiency on the ability of C. psittaci to injure L cells suggested that some synthesis of protein by both parasite and host may be essential for expression of multiplication-independent chlamydial toxicity. The failure of infectious chlamydiae to stimulate host-cell glycolysis in the presence of cycloheximide suggested that this multiplication-dependent consequence of chlamydial infection was also dependent on protein synthesis by the host.

Bacterial Proteins↗
PubMed1976

Immediate toxicity of high multiplicities of Chlamydia psittaci for mouse fibroblasts (L cells).

One hour after suspensions of mouse fibroblasts (L cells) were exposed to 500 to 1,000 L-cell 50% infectious doses of Chlamydia psittaci (6BC), the L cells failed to attach to and spread out on solid substrates, phagocytosed polystyrene latex spheres at reduced rates, incorporated less [14C]isoleucine into protein, and had smaller soluble pools of nucleoside triphosphates. The infected L cells began to die at 8 h and were all dead by 20 h. Lower multiplicities of infection took correspondingly longer to kill the L cells. These effects of high multiplicities of C. psittaci on L cells will be referred to collectively as immediate toxicity. Similar effects were obtained with other strains of C. psittaci and C. trachomatis and with other cell lines. Ultraviolet-inactivated C. psittaci retained the ability to cause immediate toxicity, but heat-inactivated chlamydiae did not. C.psittaci cells had to be ingested by L cells before they were immediately toxic but, once they were phagocytosed, they did not need to multiply or to synthesize macromolecules in order to cause immediate injury to their hosts. Immediate toxicity was not the result of depression of energy metabolism, changes in the levels of intracellular cyclic nucleotides, or release of hydrolases from lysosomes. It was suggested that a lesion is produced in the plasma membrane of the L cell every time it ingests a chlamydial cell, that each act of ingestion produces an independent lesion, and that their injurious effects are additive. Thus, the more ingestion lesions there are, the faster the host cell dies. It was also suggested that induced phagocytosis, inhibition of lysosomal fusion, and death of mice and of cells in culture may all depend on a single activity of C. psittaci.

Animals↗
PubMed1970

Glucose Metabolism of L Cells Before and After Infection with Chlamydia psittaci.

Glucose was not utilized at significantly different rates in suspensions of multiplying and nonmultiplying adult mouse fibroblasts (L cells). Infection of L cells with Chlamydia psittaci (strain meningopneumonitis) increased the rates of glucose utilization and lactate accumulation during the first 24 hr after infection without changing the rates of glucose utilization by the pentose or tricarboxylic acid cycles. It was concluded that the increased aerobic glycolysis represented a host response to infection and not a parasite activity. The 6BC strain of C. psittaci and the mouse pneumonitis strain of C. trachomatis produced similar changes in the glucose metabolism of L-cells. These results are discussed in relation to the hypothesis that chlamydiae generate to metabolic energy of their own and live by exploiting the energy-rich compounds produced by their hosts.

Journal Article↗
PubMed1968

Biosynthesis of arginine in L cells infected with chlamydiae.

Three members of the genus Chlamydia were examined for their ability to synthesize arginine, an ability their L cell (mouse fibroblasts) hosts lacked. C. psittaci (strain 6BC) multiplied in arginine-free medium 199 without significant decrease in titer and incroporated (14)C-glutamate and (14)C-ornithine into the arginine fraction of its protein. In arginine-free media, C. trachomatis (strain mouse pneumonitis) and C. psittaci (strain meningopneumonitis) grew to only 1 to 10% of the titer obtained in arginine-containing media. The decreased ability of these two strains to multiply in arginine-free media was paralleled by a decreased ability of infected host cells to incorporate (14)C-glutamate into protein arginine. These results suggest that chlamydiae either synthesize arginine themselves, or, in some unknown manner, cause their host cells to do so.

Arginine↗
PubMed1967

Initial step in catabolism of glucose by the meningopneumonitis agent.

The relative rates of catabolism of glucose and glucose-6-phosphate by intact-cell suspensions of the meningopneumonitis agent, a member of the psittacosis group (Chlamydia), and the properties of the hexokinase and glucose-6-phosphate dehydrogenase of these suspensions were investigated. It is proposed that the hexokinase is a host enzyme bound to the surface of the meningopneumonitis cell and that glucose-6-phosphate is the first substrate in the conversion of hexose to pentose to be attacked by enzymes synthesized by the meningopneumonitis agent.

Animals↗
PubMed1966

Availability of bases and nucleosides as precursors of nucleic acids in L cells and in the agent of meningopneumonitis.

Tribby, Ilse I. E. (University of Chicago, Chicago, Ill.), and James W. Moulder. Availability of bases and nucleosides as precursors of nucleic acids in L cells and in the agent of meningopneumonitis. J. Bacteriol. 91:2362-2367. 1966.-Uninfected L cells and the meningopneumonitis agent propagated in L cells utilized exogenous adenine, guanine, and their ribonucleosides and deoxyribonucleosides for synthesis of both deoxyribonucleic acid (DNA) and ribonucleic acid. Cytosine, cytidine, and uridine were also incorporated into the nucleic acids of both host and parasite. L cells and the meningopneumonitis agent incorporated uracil, thymine, and deoxyuridine very poorly. L cells utilized thymidine and deoxycytidine almost exclusively for DNA synthesis, but the meningopneumonitis agent did not incorporate these nucleosides at all. Since the L cell had previously been shown to convert added thymidine to its nucleotides, mainly the triphosphate, it was concluded that the meningopneumonitis agent can utilize neither the thymidine nor the thymidine nucleotides of the L-cell pool, and that it can probably synthesize the thymidine triphosphate needed for DNA synthesis from the uridine of the L-cell pool.

Adenine↗
PubMed1966

Autoradiographic study of deoxyribonucleic acid synthesis in L cells infected with the agent of meningopneumonitis.

Moore, Dorothy E. (University of Chicago, Chicago, Ill.), and James W. Moulder. Autoradiographic study of deoxyribonucleic acid synthesis in L cells infected with the agent of meningopneumonitis. J. Bacteriol. 92:1128-1132. 1966.-L cells infected with the agent of meningopneumonitis were labeled with H(3)-cytidine at 5-hr intervals after infection, and cell samples were fixed every 5 hr after labeling. These preparations were then digested with ribonuclease, stained by the Feulgen procedure, and examined by autoradiography. Labeled meningopneumonitis inclusions were first seen 15 hr after infection. Deoxyribonucleic acid (DNA) was synthesized in both L-cell nuclei and meningopneumonitis agent for as long as 40 hr after infection. Nuclear DNA synthesis was unaffected until 25 hr after infection, at which time synthesis of agent DNA reached its peak. After 25 hr, both meningopneumonitis and L cell DNA synthesis declined.

Autoradiography↗