Rabbit marrow cells inoculated into diffusion chambers (10(7) cells/chamber) were implanted intraperitoneally into athymic mouse hosts and cultured in vivo for 20 days. A connective tissue consisting of bone, cartilage and fibrous tissues is formed by the stromal fibroblastic cells of marrow within the chambers. Cell kinetics and tissue differentiation have been studied using histomorphometric and biochemical analyses. Haemopoietic cell numbers decrease to less than 0.05% of the initial inoculum during the 20-day period. At 3 days an average of 15 stromal fibroblastic cells only are identifiable within the chambers. After 3 days there is a high rate of stromal cell proliferation with a doubling time of 14.5 h during the period from 3 to 8 days and an increase in the total stromal cell population by more than six orders of magnitude from 3 to 20 days. Thirteen to fourteen population doublings occur before expression of the first observable differentiation parameter, alkaline phosphatase activity. The data demonstrate that the mixture of connective tissues formed within the chamber is generated by a small number of cells with high capacity for proliferation and differentiation. This is consistent with the current hypothesis that stromal stem cells are present in bone marrow.
The authors report the case of a 15-year-old female who presented with a history of vague but constant pain about the medial aspect of her right knee. X-ray established the presence of an expanding lesion in the medial tibial plateau. Computerized axial tomography (CT) and magnetic resonance imaging (MRI) were used in the evaluation of the lesion. The authors compare the preoperative CT and MRI findings with the microscopic histopathology of the amputation specimen and note that the CT scan underestimated the extent of the microscopic tumor boundaries, whereas MRI showed altered activity beyond these boundaries.
The surface and interfacial properties of a nonionic emulsifier (Tween 80) were studied in polyethylene glycol/air and polyethylene glycol/oil systems. Micelles formed and the CMC, area per surfactant mol., and free energy of adsorption of surfactant to the interface increased as functions of ethylene oxide content of the solvent mols. These changes in the surface and interfacial properties of the surfactant are apparently a result of surfactant-solvent interactions, due to H bonding. A series of oil-in-solvent emulsions was prepd. also, and the stabilities and particle size of the emulsions were mainly dependent on the adsorption energy of the surfactant. [on SciFinder(R)]
CO2 was successfully fixed in vitro as malic acid and isocitric acid using NADPH-dependent enzymes coupled to a photosensitized NADPH regeneration system. For the formation of malic acid, the enzymes involved were ferredoxin-NADP reductase (E.C. 1.18.1.2) (I) and the malic enzyme (E.C. 1.1.1.40); for isocitric acid formation, I and isocitrate dehydrogenase (E.C. 1.1.1.42) were used. [on SciFinder(R)]
Visible light-induced NADPH regeneration effects the prodn. of glutamic acid that mediates transamination and formation of aspartic acid and alanine in the presence of enzymes. [on SciFinder(R)]
NADH and NADPH were formed by a photosensitized enzyme-catalyzed process. NADPH was formed in the presence of ferredoxin NADP-reductase with Ru(bpy)32+ (bpy = 2,2'-bipyridine) as photosensitizer, Me viologen as primary electron acceptor, and (NH4)3 EDTA or 2-mercaptoethanol. Zn(II) meso-tetramethylpyridiniumporphyrin was used as photosensitizer for the photoinduced prodn. of NADH with the same reaction components but with lipoamide dehydrogenase as the enzyme catalyst. The photoinduced NADH/NADPH regeneration systems were coupled to secondary enzyme-catalyzed processes, e.g. the redn. of butan-2-one to butan-2-ol, pyruvic acid to lactic acid, or acetoacetic acid to β-hydroxybytyric acid; coupling to the reductive amination of pyruvic acid to alanine and of α-oxoglutaric acid to glutamic acid was also possible. The products showed high optical purity and the enzymes and coenzymes showed high turnover nos. and stability. [on SciFinder(R)]
Introduction.
Although a voluminous literature exists today which describes, in
great detail, the role played by "professional" phagocytes and by
serum components in the killing of pathogenic bacteria in vitro
and in vivo (l-7) very surprisingly, however, little is actually
known about the fate and mode of disposal of microorganisms once
they had been rendered non-viable by the defence systems of the
host. It is expected that the rich arsenal of lysosomal hydro-
lases, including the key muralytic enzyme lysozyme (LYZ), present
in leukocytes and in body fluids might be adequate to biodegrade
the complex structures of the microbial cells. Paradoxically,
however, the majority of bacteria are highly refractory to LYZ
action. There is also some confusion in the literature concerning
the distinction between bactericidal and bacteriolytic processes.
It is conceivable that while a major degradation of microbial cell
walls may be followed by a bactericidal reaction, the mere killing
of bacteria either by oxygen radicals (2) or by complement-dependent cytlytic antibodies (7) may not necessarily be accompanied by a
significant cell wall degradation. Many experimental models, with
laboratory animals, have distinctly shown the persistence, for very long periods, of non-viable bacteria and of undergraded microbial cell wall components, within macrophages, in chronic inflammatory sites (8-l8). Thus, one should categorically differentiate
between bactericidal and bacteriolytic phenomena. It is apparent,
therefore, that mammalian tissues fail, for still not/fully known
reasons, to biodegrade and eliminate microbial cell wall components. Peptidoglycan (PPG)-polysaccharide (PS) complexes derived
from microbial cell walls possess distinct pathobiological and and pathophysiological properties (19-21). These include the capacity to activate the complement cascade and to generate chemotactic agents, to induce fever, to activate the respiratory burst in
leukocytes and to modulate the immune responses (19-24), to mention only a few of the plethora of functions ascribed to PPG.
These properties may also explain the very complex interrelationships which exist between the parasite and the host during microbial infections and the possible reasons for the development of
certain post-infectious sequelae, which involve the prolonged persistence of bacterial cell wall components in tissues (10-15).
Liquoid (polyanethole sulfonate) was neither capable of influencing the growth nor the viability of staphylococci. But liquoid induced a suppression of the activity of different autolytic wall systems of normally growing staphylococci, i.e., autolysins which participate in cross wall separation as well as autolysins which are responsible for cell wall turnover. Additionally, the lysostaphin-induced wall disintegration of staphylococci was inhibited by liquoid. However, no indication could be found for a direct inhibition of lytic wall enzymes by liquoid; rather an interaction of liquoid with the target structure for the autolytic wall enzymes, the cell wall itself, was postulated. On the basis of the experimental data with the teichoic acid- mutant S. aureus 52A5 the sites of wall teichoic acid were supposed to be an important target for the binding of liquoid to the staphylococcal cell wall.
Introduction
Cationic polyelectrolytes play important roles in many biological
systems. Histones [20] and cationic proteins of lysosomal
origin [8, 18, 24, 25, 28, 33, 36, 37], both rich in
arginine, and synthetic poly a-amino acids [3, 4, 5, 6, 23,
30] have been shown to be bactericidal and cytotoxic to a
variety of bacteria and mammalian cells. In addition, these
compounds modulate blood coagulation [30] and fibrinolysis
[10]; agglutinate bacteria and mammalian cells [30];
modulate chemotaxis [16]; enhance adherence of mammalian
cells to surfaces [26]; function as opsonins for phagocytosis
by both "professional" and "nonprofessional" cells
[3,5,6,17,27,28,34]; activate autolytic cell wall enzymes
of Staphylococci [15]; and block Fe receptors for IgG upon
certain group A Streptococci [14]. More recent studies have
shown that histone-opsonized bacteria induced intense Iuminot-
dependent chemiluminescence (LDCL) in human
polymorphonuclear leukocytes (PMNs) and mouse peritoneal
macrophages [In Furthermore, poly-i.-arginine collaborated
with mixtures of lectins, calcium ionophore and
the chemotactic peptide formyl-methionyl-Ieucyl-phenylalanine
to induce synergistic LDCL and superoxide production
in human PMNs [12,13]. Thus, arginine-rich polyelectrolytes
appear to participate in many cellular functions related
to host defenses against infection, presumably by
mechanisms involving electrostatic interactions and ligand-
receptor coupling phenomena. The objective of this
present study was to investigate the possibility that arginine-
rich polycations might facilitate the introduction of a variety of agents into eukaryotic cells. For this purpose, we
have studied phagocytosis by Entamoeba histolytica of
Candida albicans, and by Acanthamoeba palestinensis of
Mycobacterium marinum.
