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C Panos

Publications and source records attributed to C Panos.

At least 19 recordsLinked to original sources

Streptococcus pyogenes clinical isolates and lipoteichoic acid.

Minimally subcultured clinical isolates of virulent nephritogenic and nonnephritogenic Streptococcus pyogenes of the same serotype showed major differences in lipoteichoic acid (LTA) production, secretion, and structure. These were related to changes in coccal adherence to and destruction of growing human skin cell monolayers in vitro. A possible relationship between cellular LTA content and group A streptococcal surface hydrophobicity was also investigated. Nephritogenic S. pyogenes M18 produced twice as much total (i.e., cellular and secretory) LTA as did the virulent, serologically identical, but nonnephritogenic isolate. Also, the LTAs from these organisms differed markedly. The polyglycerol phosphate chain of LTA from the nephritogenic isolate was longer (1.6 times) than was that from the nonnephritogenic isolate. Likewise, both LTAs indicated the presence of alanine and the absence of glucose. Amino sugars were found in LTA from only nephritogenic S. pyogenes. Teichoic acid, as a cellular component or secretory product, was not detected. The adherence of two different nephritogenic group A streptococcal serotypes (M18 and M2) exceeded that of the serologically identical but nonnephritogenic isolates (by about five times), indicating a correlation between virulent strains causing acute glomerulonephritis and adherence to human skin cell monolayers. Likewise, LTA from nephritogenic S. pyogenes M18 was more cytotoxic (1.5 times) than was that from the nonnephritogenic isolate for human skin cells, as determined by protein release. This difference was not perceptible by the more sensitive dye exclusion method (i.e., requiring less LTA), which emphasizes changes in host cell morphology and death. Also, the secretion of LTA by only virulent nephritogenic S. pyogenes M18 was exacerbated by penicillin (a maximum of four times). Finally, while the adherence of nephritogenic S. pyogenes M18 decreased markedly after continued subculturing in vitro, the surface hydrophobicity did not.

Animals↗

[Granulomatous cheilitis. Case report].

A case of granulomatous cheilitis, an uncommon disease that is difficult to be treated is described. The disease is of unknown etiology and it may represents a monosymptomatic form of Melkersson-Rosenthal syndrome. The significance of the clinical lesions, the microscopic features as well as the recent aetiological aspects of the disease are discussed.

Adult↗

Adherence of Streptococcus agalactiae to synchronously growing human cell monolayers without lipoteichoic acid involvement.

Freshly isolated virulent and nonvirulent strains of Streptococcus agalactiae type III were used to study differences in coccal adherence to synchronously dividing, subconfluent human embryonic amnion and fetal lung monolayers in vitro. The adherence frequency by virulent isolates of mid-logarithmically growing cocci to amnion cells varied markedly with host cell age, being highest shortly after eucaryotic cell division. This variation was not observed with lung cell monolayers, suggesting that cyclic production or exposure of coccal receptor sites on the eucaryotic cell surface with age is not a common property of all primary human cells in vitro. However, and regardless of age, not all cells within these synchronously dividing populations bound virulent cocci, indicating that a very small segment of a population may always be unresponsive to host cell interactions with a coccal pathogen. By comparison, adherence of nonvirulent coccal isolates to amnion and lung cells remained constant and of a very low order, regardless of host cell age. Maximal adherence of virulent S. agalactiae to young host cells occurred at early and mid-logarithmic phases of growth. However, at the late stationary growth phase, adherence was reduced to almost that of nonvirulent isolates. Pretreatment of virulent S. agalactiae with anti-lipoteichoic acid (LTA) serum failed to inhibit coccal adherence to these different host cells. Heat negated adherence. Group B coccal LTA was cytotoxic for these host cells. However, pretreatment of amnion and lung cells with nontoxic levels of this amphiphile did not prevent attachment of virulent cocci. Finally, coccal pretreatment with pronase abrogated adherence to either host cell even though surface-exposed LTA was uneffected, as observed by the indirect fluorescent-antibody procedure. Likewise, no observable difference in surface LTA was detected when fresh isolates of virulent and nonvirulent coccal strains were compared by this procedure. These studies suggest that protein involvement, rather than LTA, is primarily responsible for mediating virulent S. agalactiae type III attachment to these synchronously growing, subconfluent eucaryotic monolayers in vitro.

Bacterial Adhesion↗

Differences in penicillin-binding proteins of Streptococcus pyogenes and two derived, stabilized L forms.

The penicillin-binding proteins (PBPs) of Streptococcus pyogenes and two of its derived, stabilized (i.e., nonreverting) L forms, an osmotically fragile L form and a physiologic isotonic L form, were compared. The numbers of PBPs in the membranes of these organisms were 6, 4, and 2 for the coccus and the osmotically fragile and physiologic isotonic L forms, respectively. Likewise, the relative amounts of total PBPs were 1.00: 1.48:0.32 for this coccus and the osmotically fragile and physiologic isotonic L forms, respectively. The two largest PBPs (PBPs 1 and 2) of the coccus were absent in both L forms, while the smallest PBPs (PBPs 5 and 6) were found in all three membranes. Deacylation (half-life) of three of the four PBPs in the osmotically fragile L form membrane required a significantly longer time than did deacylation of these presumed identical enzymes in the parental coccal membrane. Conversely, there was no such difference between the only two PBPs of the physiologic isotonic L form and the same coccal membrane proteins. Intact cells of all three organisms secreted PBPs and what appeared to be penicilloic acid and a minimal amount of free penicillin. A greater amount of these PBPs was secreted by both L forms than by the coccus. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns and ratios of secreted PBPs were identical to those from labeled membrane preparations. These differences are correlated with some of our previous findings and are discussed in terms of inhibition of cell wall synthesis and resulting membrane changes in these two derived, stabilized coccal L forms.

Bacterial Proteins↗

An electron microscope study of kidney basement membrane changes in the mouse by lipoteichoic acid from Streptococcus pyogenes.

Mice injected repeatedly, intraperitoneally or intravenously, for approximately 1 month with a total of 1.04 mg lipoteichoic acid from a nephritogenic strain of Streptococcus pyogenes lost weight. Analysis by electron microscopy revealed that they also exhibited extensive kidney changes in basement membrane morphology which resembled, in part, those observed in human poststreptococcal glomerulonephritis. For example, the glomerular basement membrane became electron dense and exhibited at least a twofold increase in width sporadically within the same preparation after exposure to lipoteichoic acid. Also, whereas appreciable loss or reduction in epithelial foot processes as a result of fusion was clearly evident, epithelial slits and slit membranes or diaphragms between normal foot processes were not selectively affected. In addition, another mostly thickened, highly coiled or serpentinelike basement membrane with amorphous nodules appeared in these preparations. This type membrane was not observed surrounding the capillary lumina and was the most pronounced abnormality apparent in almost all preparations from mice exposed to lipoteichoic acid. Likewise, the proximal tubular basement membrane became variable in width and increased in electron density in mice given lipoteichoic acid as compared with controls. In addition, this membrane was often punctuated with various morphological protrusions originating from only its thickened areas and which extended away from, and not into, the capillary space. This change was only associated with the basement membrane of the proximal tubular capillaries. All membrane changes persisted but gradually subsided, with normal kidney membrane morphology reappearing on the 4th day following the last injection of lipoteichoic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effect of streptococcal lipoteichoic acid on prolyl hydroxylase activity as related to collagen formation in mouse fibroblast monolayers.

Dried and wet mouse fibroblast monolayers with labeled collagenous substrate were used to study the effects of lipoteichoic acid (LTA) on cellular prolyl hydroxylase activity. LTA is a scavenger of cations, and Fe2+ is essential for prolyl hydroxylase activity. Surprisingly, addition of LTA to dried monolayers resulted in increased prolyl hydroxylase activity, whereas preincubation of Fe2+ with LTA only negated this increase. However, significant inhibition of enzyme activity by wet monolayers occurred whether LTA was added directly to the test system or whether it was used after preincubation with Fe2+. These data suggest that LTA causes membrane perturbations. Also, that the binding of LTA to the membrane of dried and wet monolayers appears to be decidedly different when based on the subsequent availability of Fe2+ for cellular prolyl hydroxylase activity. The ability of LTA to act as a cationic exchanger and the presence of intracellular Fe2+ inaccessible to LTA probably accounted for the lack of complete inhibition of prolyl hydroxylase activity by this amphiphile in the wet cell system. Considerably less iron was needed to negate the partial inhibition of prolyl hydroxylase activity by LTA in viable cells than was needed to restore the increased enzyme activity by this amphiphile in equivalent dried preparations. These and other results showed that, although LTA does not affect collagen polypeptide chain formation in wet monolayers, its involvement at the molecular level does result in a marked decrease in the hydroxylation of collagenous peptidyl prolyl residues through LTA interaction with Fe2+. This reduction in prolyl hydroxylase activity equaled the reduction in hydroxylation of collagenous protein in fibroblast monolayers caused by LTA reported earlier (O. Leon and C. Panos, Infect. Immun. 40:785-794, 1983). Therefore, these data suggest that partial inhibition of prolyl hydroxylase activity is directly related to the synthesis of defective collagen by wet fibroblast monolayers exposed to minute amounts of group A, type 12 streptococcal LTA. Use of LTA also showed that complete inhibition of hydroxyproline formation is not required for the continued formation and accumulation of defective collagenous protein by these monolayers.

Animals↗

Teichoic acids of Streptococcus agalactiae: chemistry, cytotoxicity, and effect on bacterial adherence to human cells in tissue culture.

The ratio of teichoic acid to lipoteichoic acid (LTA) in a strain of Streptococcus agalactiae type III was found to be 8:1, with the total amount of LTA being 0.1% of the dry weight of the organism. Purified teichoic acid contained D-alanine and possibly a small amount of D-glucose and was approximately 22 glycerol phosphate units in length. The linkage between each of these units was 1-3. In addition, LTA contained a complex lipid, more glucose, and an unusually high content of a short-chain fatty acid, tridecanoic acid. This LTA was cytotoxic for a variety of human cell monolayers in tissue culture, including one derived from the human central nervous system. Established human cells were more sensitive than primary cell monolayers to this LTA, with as little as 12.5 micrograms of LTA per ml being cytotoxic for HeLa cells. Teichoic acid (250 micrograms/ml) was nontoxic under identical conditions. These cytotoxicity results suggest an LTA involvement in group B streptococcal pathogenesis. Also, the first model system for the study of group B streptococcal adherence to primary human embryonic amnion cells in tissue culture is detailed. This system was used to quantitate pronounced differences in tissue tropism between S. agalactiae and Streptococcus pyogenes and showed enhanced binding by this group A coccus over that of S. agalactiae for amnion cell monolayers. The adherence of both streptococcal species to only a portion (40%) of these amnion cells suggested that host cell receptor expression may vary for primary cells in vitro. Finally, this strain of S. agalactiae was shown to adhere to amnion cells by a non-LTA-mediated mechanism. The possibility of an LTA-mediated versus a protein-mediated adherence mechanism for host cells that is related to the virulence of S. agalactiae is discussed.

Adhesiveness↗

Cytotoxicity and inhibition of normal collagen synthesis in mouse fibroblasts by lipoteichoic acid from Streptococcus pyogenes type 12.

The toxicity of lipoteichoic acid (LTA) from Streptococcus pyogenes type 12 was investigated by using mouse fibroblasts in culture in the absence of serum. Morphologically, while low concentrations of LTA elicited a subtle effect characterized by progressive cellular degeneration with practically no release of protein, larger concentrations (greater than 50 micrograms/ml) of this amphiphile resulted in rapid death of cell monolayers. Metabolic studies utilized a concentration of LTA (17.5 micrograms/ml) which caused the smallest change in cell morphology in the least number of mouse fibroblast cells per monolayer. Under these conditions, cell monolayers showed an increase of 450% in their content of collagenous protein after exposure to LTA. However, the amount of such material secreted remained unchanged. Also, changes in the type of collagenous protein formed were observed after exposure to LTA. Collagenous protein accumulating intracellularly was found to be practically hydroxyproline-free. However, collagenous protein secreted by this cell line showed a significantly reduced content of hydroxyproline as compared with control cells unexposed to this coccal membrane component. Column chromatographic studies confirmed that the collagenous protein secreted by monolayers exposed to LTA was defective (under hydroxylated). It was concluded that LTA does not affect the amount of collagenous protein secreted. However, it does increase the amount of this protein formed and retained by this cell line as well as causing a reduction in the hydroxylation of proline in both intracellular and secreted collagenous material. A possible relationship between abnormal basement membrane morphology and disturbed collagen synthesis in post-streptococcal glomerulonephritis as related to LTA is discussed.

Animals↗

Morphological changes and pathology of mouse glomeruli infected with a streptococcal L-form or exposed to lipoteichoic acid.

The morphology and pathology of cultured mouse glomeruli were examined at the cellular and subcellular levels after infection with a physiological isotonic L-form of Streptococcus pyogenes type 12 or exposure to streptococcal lipoteichoic acid. These changes, as viewed by light microscopy, were identical regardless of the method used to induce glomerular cytotoxicity. They were characterized by an initial reduction in the outgrowth of cells, some cellular granulation, and later, destruction of the confluent monolayer. Once initiated, cytotoxicity could not be reversed by refeedings, and complete glomerular destruction resulted after 2 weeks. Electron microscope studies revealed that the basement membrane of intact glomeruli exposed to streptococcal lipoteichoic acid had become greatly thickened (two- to fourfold) and electron dense. Our recent biochemical findings have shown that streptococcal lipoteichoic acid increases the amount of collagen formed and retained by mouse fibroblasts in tissue culture as well as causing a reduction in the hydroxylation of proline in both intracellular and secreted collagenous material (Leon and Panos, Infect. Immun. 40:785-794, 1983). These results, together with the present findings, suggest that the thickening of the glomerular basement membrane may be due to defective collagen biosynthesis as a result of streptococcal lipoteichoic acid. The use of cultured glomeruli as a model system for studying the earliest basement membrane alterations in the absence of an immune response as a result of streptococcal lipoteichoic acid is suggested.

Animals↗

Mechanism of inducer expulsion in Streptococcus pyogenes: a two-step process activated by ATP.

The mechanism of methyl-beta-D-thiogalactoside-phosphate (TMG-P) expulsion from Streptococcus pyogenes was studied. The expulsion elicited by glucose was not due to exchange vectorial transphosphorylation between the expelled TMG and the incoming glucose since more beta-galactoside was displaced than glucose taken up, and the stoichiometry between TMG and glucose transport was inconstant. Instead, two distinct and sequential reactions, intracellular dephosphorylation of TMG-P followed by efflux of free TMG, mediated the expulsion. This was shown by temporary accumulation of free TMG effected by competitive inhibition of its efflux and by the aid of arsenate, which arrested dephosphorylation of TMG-P but did not affect efflux of free TMG formed intracellularly before arsenate addition. The competitive inhibition of TMG efflux by its structural analogs suggests that a transport protein facilitates the expulsion. Iodoacetate or fluoride prevented TMG-P dephosphorylation and its expulsion. However, provision of ATP via the arginine deiminase pathway restored these activities in the presence of the glycolytic inhibitors and stimulated expulsion in their absence. Other amino acids tested did not promote this restoration, and canavanine or norvaline severely inhibited it. Arginine without glucose neither elicited the dephosphorylation nor evoked the expulsion of TMG-P. Ionophores or ATPase inhibitors did not prevent the expulsion as elicited by glucose or its restoration by arginine. The results suggest that activation of the dephosphorylation-expulsion mechanism occurs independently of a functional glycolytic pathway, requires ATP provision, and is possibly due to protein phosphorylation controlled by a yet unknown metabolite. The in vivo phosphorylation of a protein (approximate molecular weight - 10,000) under the conditions of expulsion was demonstrated.

Adenosine Triphosphatases↗

Transport of alpha-aminoisobutyric acid by Streptococcus pyogenes and its derived L-form.

We studied the uptake of alpha-aminoisobutyric acid (AIB) in Streptococcus pyogenes and its physiologically isotonic L-form. S. pyogenes cells starved for glucose or treated with carbonyl cyanide-m-chlorophenyl hydrazone accumulated limited amounts of AIB. A high apparent K(m) value characterized the glucose-independent transport of AIB. The rate and extent of AIB accumulation significantly increased in the presence of glucose. Two saturable transport components with distinct apparent K(m) values characterized glycolysis-coupled transport of AIB. A biphasic Lineweaver-Burk plot was also obtained for l-alanine transport by glycolyzing S. pyogenes cells. AIB seems to share a common transport system(s) with glycine, l- and d-alanine, l-serine, and l-valine. This was shown by the competitive inhibition of AIB uptake by these compounds and their ability to induce competitive exchange efflux of accumulated AIB. About 30% of the AIB uptake was not inhibited by a saturating amount of l-valine, indicating the existence of more than one system for AIB transport. p-Chloromercuribenzoate markedly inhibited the accumulation of AIB by both glycolyzing and glucose-starved cells. In contrast, carbonyl cyanide-m-chlorophenyl hydrazone affected only metabolism-dependent uptake of AIB, which was also sensitive to dinitrophenol, N-ethylmaleimide, iodoacetate, fluoride (NaF), arsenate, and N,N'-dicyclohexylcarbodiimide. These results are interpreted according to the chemiosmotic theory of Mitchell, whereby a proton motive force constitutes the driving force for AIB accumulation. AIB was not accumulated by the L-form. However, a temporary accumulation of AIB by a counterflow mechanism and a saturable system with a low apparent affinity were demonstrated for AIB transport by this organism. We suggest that a deficiency in the coupling of energy to AIB transport is responsible for the apparent lack of active AIB accumulation by the L-form.

Alanine↗

Long-chain fatty acid perturbations in Mycoplasma pneumoniae.

The fatty acid content of Mycoplasma pneumoniae increased 2.5- to 9.6-fold when the growth medium was supplemented with a saturated, unsaturated, or beta-hydroxy fatty acid, the greatest increase occurring with palmitic acid. The amount of each supplemented fatty acid found within this organism was 2.8 to 5.5% of the total fatty acid content; the exception was palmitic acid. Up to 57% of the palmitic acid was utilized from the supplemented medium, whereas only 0.2 to 10% of the other fatty acids was utilized. Chromatographic and isotopic analyses revealed that 22% of the labeled palmitic acid incorporated from the palmitic acid-supplemented medium remained free in this organism. Also, even though complex lipid synthesis increased a minimum of 3.8-fold under these conditions, this mycoplasma continued to incorporate intact complex lipids from the growth medium. Bacteriostatic and bactericidal studies which used high concentrations of various long-chain fatty acids showed that only palmitic, myristic, and beta-hydroxydecanoic acids were not bactericidal. The addition of palmitic acid to the growth medium resulted in the formation of exceedingly long, filamentous cells in approximately 25% of the population. Osmotic fragility and electron spin resonance spectroscopy studies showed a correlation among this increased fatty acid content, decreased membrane fluidity, and the increased osmotic fragility of palmitic acid-grown cells. In addition, these cells had a lowered cholesterol content. The effect of such compositional changes on osmotic fragility is discussed in this paper. Finally, the profound increase in the total fatty acid content of palmitic acid-grown cells altered neither sensitivity to tetracycline or erythromycin nor the amount of hydrogen peroxide secreted.

Fatty Acids↗

Regulation of beta-galactoside phosphate accumulation in Streptococcus pyogenes by an expulsion mechanism.

Streptococcus pyogenes pregrown on lactose took up glucose, lactose, or methyl beta-D-thiogalactopyranoside (MeSGal or TMG) by a phosphoenolpyruvate-dependent phosphotransferase system. MeSGal accumulated in the cell as MeSGal-phosphate (MeSGalP). Three effects were noted when various sugars were added to MeSGal preloaded cells: (i) no decrease in intracellular MeSGalP concentration after addition of fructose, sucrose, o-nitrophenyl-beta-D-galactoside, glycerol, 6-deoxyglucose, alpha-methyl D-glucoside, 2-deoxygalactose, glucose 1-phosphate, or glucose 6-phosphate; (ii) slow loss of preaccumulated MeSGalP evoked by lactose, 2-deoxy-D-glucose, or unlabeled MeSGal; and (iii) a short lag followed by extremely rapid expulsion of intracellular MeSGalP elicited by glucose or mannose and a slower expulsion elicited by glucosamine. The expelled compound was free MeSGal, indicating the involvement of dephosphorylation in the expulsion mechanism. Deoxyglucose inhibited the expulsion evoked by mannose, and prepoisoning of cells with fluoride or arsenate prevented the glucose-dependent expulsion. The expulsion is due to activation of an expulsion mechanism rather than to turnover of MeSGalP and leak of internal MeSGal with concomitant inhibition of MeSGal influx. The results suggest the need for phosphotransferase-dependent translocation of a preferential sugar or accumulation of the sugar catabolite for expulsion activation. The significance of the expulsion mechanism in synthesis regulation of enzymes involved in carbohydrate utilization is proposed.

Arsenates↗

Evidence that Streptococcus mutans constructs its membrane with excess fluidity for survival at suboptimal temperatures.

When cells from cultures of Streptococcus mutans strain FA-1 grown at 37 degrees C were exposed to incubation temperatures of 26 degrees C or less for 5 min or more, an extensive aggregation of particles was observed on the convex fracture faces of their freeze-cleaved membranes. Aggregation of particles was accompanied by a parallel increase in the activation energy for growth. By shifting the growth temperature from 37 to 24 degrees C for one doubling of culture mass, the transition temperature for membrane particle aggregation could be lowered from about 26 to 0 degrees C. Although membrane lipids became enriched with unsaturated fatty acids during this period of growth at 24 degrees C, this enrichment was not accompanied by an increased growth rate of the culture. However, the period of growth at 24 degrees C did result in bacteria that could grow more rapidly at 10 degrees C than could bacteria directly transferred from cultures grown at 37 degrees C. These observations suggest that the increase in membrane fluidity that occurs when bacteria are grown at 24 degrees C doses not allow bacteria to grow faster at 24 degrees C, but rather allows them to adapt more readily to further decreases in growth temperature.

Cell Membrane↗

Effect of L-form Streptococcus pyogenes and of lipoteichoic acid on human cells in tissue culture.

These studies showed the destruction of growing primary and established human cell lines with a predilection for the group A streptococci by an L-form of Streptococcus pyogenes adapted to grow in isotonic media. Also, this L-form was detected by fluorescent antibody for longer periods of time than by viable count in infected but recovered tissue culture monolayers. Additional studies with human heart cells showed changes in their protein profile and fatty acid content (but not composition) after L-form infection. This report is the first to show that the morphological changes and death of human kidney cells by this viable L-form were mimicked by the structurally different lipoteichoic acids from this organism and its parental streptococcus. These lipoteichoic acids were also equally effective in preventing attachment of S. pyogenes to human cell monolayers, but their deacylation obviated these two activities. Finally, the attachment of the isotonic L-form, as well as the parental streptococcus, to growing human kidney cells suggested that a rigid cell wall is not a prerequisite for host attachment in vitro.

Cell Line↗

Synthesis of "group polysaccharide" by membranes from Streptococcus pyogenes and its stabilized L-form.

Rhamnose and N-acetylglucosamine (GlcNAc) are incorporated from thymidine 5'-diphosphorhamnose and uridine 5-diphospho-N-acetylglucosamine (UDPGlcNAc) into membrane fragments prepared from Streptococcus pyogenes but not into membrane fragements prepared from a stabilized L-form of this organism. Incorporation from TDPrhamnose is partially dependent upon UDPGlcNAc and vice versa. The oligomeric GlcNAc and rhamonose-containing products are easily extracted from membrane particles by sedimentation through detergent solutions. They are substantially extracted into methanol but not into chloroform-methanol (2:1). When product containing both radioactive rhamnose and GlcNAc is deacetylated and hydrolyzed briefy in acid, glucosaminyl rhamnose is obtained, byt not higher oligomers, suggesting that oligomer synthesis in vitro is terminated because unidentified wnzymatic requirements are not satisfied. The data are consistent with the assembly of group A-specific polysaccharide at the cellular membrane with participation of a lipoid anchor (acceptor) molecule.

Acetylglucosamine↗

Wall-less microbial isolate from a human renal biopsy.

An orgainsm was isolated from a kidney biopsy of a patient with renal failure. Electron microscopy revealed an ultrastructure very similar to that of a bacterial L-form or mycoplasma. But macroscopically, its colonial morphology was unusual and distinct from that ascribed to these wall-less organisms. This isolate lacked a rigid cell wall and required a hypertonic medium with serum for growth. Also, a long incubation period was essential for its growth, and use of hand lens was necessary for detection on solid medium.

Biopsy, Needle↗