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PubMed1964

ANTIGENIC RELATIONSHIPS BETWEEN GROUPS B AND G STREPTOCOCCI.

Trypsinized cell walls of Group B hemolytic streptococci are composed of a group-specific carbohydrate and mucopeptide. The carbohydrate extracted with hot formamide is composed of rhamnose, N-acetylglucosamine, and galactose. Quantitative precipitin inhibition studies have shown that L rhamose is the significant component of the antigenic determinant. The cross-reactivity between B and G carbohydrates is dependent upon the fact that Lrhamose is a determinant sugar in both antigens.

Antigens↗
PubMed1965

THE CELL WALLS OF GROUP D STREPTOCOCCI. I. THE IMMUNOCHEMISTRY OF THE TYPE 1 CARBOHYDRATE.

Group D Types 1 and 26 cell walls and the corresponding type-specific carbohydrates, extracted from the walls by various means, contain rhamnose, glucose, galactose, N-acetylglucosamine, and N-acetylgalactosamine. Mucopeptide elements are also present in the walls and in enzymatically-extracted carbohydrates. Types 1 and 26 carbohydrates extracted by formamide contain no mucopeptide, but the serologic reactivity of Type 1 antigen is destroyed by this procedure. The Type 1 antigen was successfully extracted, however, by a new technique involving autolysis of cell walls at pH 6.2. The type carbohydrate prepared by this procedure has chemical and serological similarities to the antigens prepared by the S. albus enzyme and the lysozyme methods. Quantitative precipitin inhibition studies with Type 1 antigen and antibody indicate that D-glucose and N-acetylglucosamine may be components of the antigenic determinant. The terminal residue is probably bound by an beta-glycosidic bond to the subterminal sugar. Similar studies with the Type 26 carbohydrate have not revealed any of the chemical features of the antigenic determinant.

Antibodies↗
PubMed1967

Immunochemical studies on the group and type antigens of group F streptococci and the identification of a grouplike carbohydrate in a type II strain with an undesignated group antigen.

Two antigens, the group-specific carbohydrate and the Type II carbohydrate, have been isolated by cellulose column chromatography from a formamide extract of a Group F streptococcus. Chemical and immunologic analyses indicate that both antigens are free of other cellular components. Both antigens are components of the cell wall although the Type II antigen is probably more superficial than the group antigen. The Type II antigen is composed of rhamnose, glucose, galactose, and galactosamine. The Group F antigen is composed of rhamnose, glucose, galactosamine and a small percentage of glucosamine. A grouplike carbohydrate and the Type II carbohydrate have been isolated from a streptotoccal strain which lacks a serologically detectable streptococcal group antigen. This grouplike carbohydrate, which does not cross-react immunologically with Group F serum, is composed of rhamnose, galactose, and glucosamine. No chemical or immunological differences were observed between the Type II antigen isolated from the Group F strain and the Type II antigen isolated from the nongroupable strain.

Animals↗
PubMed1952

Group A streptococcus polysaccharide: studies on its preparation, chemical composition, and cellular localization after intravenous injection into mice.

A method was developed for the extraction of the group A streptococcus polysaccharide employing pepsin digestion of ground streptococcal cells. This method did not result in the isolation of polysaccharide with chemical and physical chemical properties different from those exhibited by preparations extracted with hot formamide. Studies of the chemical composition of this polysaccharide demonstrated it to be composed chiefly of rhamnose and glucosamine monosaccharide units in the approximate ratio of five moles of rhamnose to two moles of glucosamine. The fate of the polysaccharide after intravenous injection into mice was studied using the fluorescent antibody technique. It was found to be rapidly eliminated by the kidney. The presence of the polysaccharide in the renal tubular epithelial cells during the excretory phase was the only evidence of its cellular localization that could be detected under the conditions of these experiments.

Animals↗
PubMed1970

Transport parameters in a porous cellulose acetate membrane.

The transport parameters of a cellulose acetate membrane prepared from a mixture of cellulose acetate, formamide, and acetone, 25:25:50 by weight, were studied. The membrane consists of a thin, porous layer, the skin, in series with a thick, highly porous layer, the coarse support. In the skin the diffusional permeability coefficient, omega, of a number of small amides and alcohols depends critically upon the partition coefficient, K(s), the size of the molecule, and the apparent hydrogen-bonding ability, N(s), of the solute. These observations are in general agreement with our earlier conclusions on the properties of nonporous membranes. On the other hand, the corrected reflection coefficient, sigma', is not a very sensitive function of either N(s) or K(s) taken separately. The correlation between sigma' and molecular diameter is reasonably good; however, it is much improved when both N(s) and K(s) are taken into consideration. Isotope interaction was also studied in the present preparation and was found to provide only a small (5-8%) contribution to the diffusional permeability coefficient of ethylene glycol. The contribution of solute-water friction was found to be less than 24% of the total solute friction.

Acetates↗
PubMed1976

Nonelectrolyte diffusion across lipid bilayer systems.

The permeability coefficients of a homologous series of amides from formamide through valeramide have been measured in spherical bilayers prepared by the method described by Jung. They do not depend directly on the water:ether partition coefficient which increases regularly with chain length. Instead there is a minimum at acetamide. This has been ascribed to the effect of steric hindrance on diffusion within the bilayer which increases with solute molar volume. This factor is of the same magnitude, though opposite in sign to the effect of lipid solubility, thus accounting for the minimum. The resistance to passage across the interface has been compared to the resistance to diffusion within the membrane. As the solute chain length increases the interface becomes more important, until for valeramide it comprises about 90% of the total resistance. Interface resistance is also important in urea permeation, causing urea to permeate much more slowly than an amide of comparable size, after allowance is made for the difference in the water:ether partition coefficient. Amide permeation coefficients have been compared with relative liposome permeation data measured by the rate of liposome swelling. The ratios of the two measures of permeation vary between 3 and 16 for the homologous amides. The apparent enthalpy of liposome permeation has been measured and found to be in the neighborhood of 12 kcal mol-1 essentially independent of chain length. Comparison of the bilayer permeability coefficients with those of red cells shows that red cell permeation by the lipophilic solutes resembles that of the bilayers, whereas permeation by the hydrophilic solutes differs significantly.

Amides↗
PubMed1978

Selectivity of cations and nonelectrolytes for acetylcholine-activated channels in cultured muscle cells.

The selectivity of acetylcholine (A-Ch)-activated channels for alkali cations, organic cations, and nonelectrolytes in cultured muscle cells has been studied. To test the effect of size, charge, and hydrogen-binding capacity of permeant molecules on their permeability, we have obtained the selectivity sequences of alkali cations, compared the permeability of pairs of permeant molecules with similar size and shape but differing in charge, and studied the permeability of amines of different hydrogen bonding capacity. ACh-activated channels transport alkali cations of small hydration radii and high mobility. The molecules with positive charge and (or) a hydrogen-bond donating moiety are more permeable than the ones without. On the other hand, several nonelectrolytes, i.e., ethylene glycol, formamide, and urea, do have a small, but measurable, permeability through the channels. These results are consistent with a model that ACh-activated channel is a water-filled pore containing dipoles or hydrogen bond accepting groups and a negative charged site with a pK of 4.8.

Animals↗
PubMed1989

Hydrostatic pressures developed by osmotically swelling vesicles bound to planar membranes.

When phospholipid vesicles bound to a planar membrane are osmotically swollen, they develop a hydrostatic pressure (delta P) and fuse with the membrane. We have calculated the steady-state delta P, from the equations of irreversible thermodynamics governing water and solute flows, for two general methods of osmotic swelling. In the first method, vesicles are swollen by adding a solute to the vesicle-containing compartment to make it hyperosmotic. delta P is determined by the vesicle membrane's permeabilities to solute and water. If the vesicle membrane is devoid of open channels, then delta P is zero. When the vesicle membrane contains open channels, then delta P peaks at a channel density unique to the solute permeability properties of both the channel and the membrane. The solute enters the vesicle through the channels but leaks out through the region of vesicle-planar membrane contact. delta P is largest for channels having high permeabilities to the solute and for solutes with low membrane permeabilities in the contact region. The model predicts the following order of solutes producing pressures of decreasing magnitude: KCl greater than urea greater than formamide greater than or equal to ethylene glycol. Differences between osmoticants quantitatively depend on the solute permeability of the channel and the density of channels in the vesicle membrane. The order of effectiveness is the same as that experimentally observed for solutes promoting fusion. Therefore, delta P drives fusion. When channels with small permeabilities are used, coupling between solute and water flows within the channel has a significant effect on delta P. In the second method, an impermeant solute bathing the vesicles is isosmotically replaced by a solute which permeates the channels in the vesicle membrane. delta P resulting from this method is much less sensitive to the permeabilities of the channel and membrane to the solute. delta P approaches the theoretical limit set by the concentration of the impermeant solute.

Hydrostatic Pressure↗
PubMed1982

Isolation and characterization of IFN-gamma mRNA derived from mitogen-induced human splenocytes.

Human splenocytes from large cultures (5 1) were stimulated with Staphylococcus enterotoxin A (SEA). After 2.5 d of conditioning, poly A+RNA was isolated from these cultures and its in-vitro translational capacity was evaluated in a wheat germ extract. Injection of the RNA into Xenopus laevis oocytes yielded a low but reproducible amount of IFN activity, which was neutralizable only by an antiserum to gamma interferon (IFN-gamma) and not by antisera to alpha interferon (IFN-alpha) and/or beta interferon (IFN-beta). Formamide sucrose gradient centrifugation analysis indicated that the mRNA which codes for IFN-gamma sediments at around 15 S. The profile, however, suggested a size heterogeneity of IFN-specific mRNA. Electrophoresis of cDNA synthesized on these mRNA fractions indicated that the mRNA coding for gamma IFN has a length of between 900 and 1400 nucleotides.

Animals↗
PubMed1991

In vitro transformation of rat bladder epithelium by 2-amino-4-(5-nitro-2-furyl)thiazole.

To establish a rat urinary bladder carcinogenesis model in vitro, primary rat bladder epithelial cells were grown in media containing 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT), the water-soluble metabolite of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT), for 4 weeks followed by long-term (4-7 months) exposure to control medium, sodium saccharin (NaS), or urea. Another set of cultures were exposed to ANFT, NaS and urea simultaneously. Several phenotypic changes were observed in the chemically exposed cell cultures, namely differences in cell morphology, increased growth rate and the ability to grow on plastic instead of rat-tail collagen support. All of the chemically exposed cultures were anchorage independent except one of those treated with NaS. The ANFT-treated cells followed by control medium or urea and cells treated with ANFT, NaS and urea were tumorigenic when transplanted to nude mice, whereas NaS or ANFT followed by NaS treatment were not. The tumors were carcinomas and their epithelial differentiation was verified by strong positive staining for cytokeratin. These studies demonstrate the urothelial transforming capability of ANFT in cell culture without the necessity for a long exposure to a secondary chemical.

Animals↗
PubMed1992

Absence of ras oncogene activation in rat urinary bladder carcinomas induced by N-methyl-N-nitrosourea or N-butyl-N-(4-hydroxybutyl)nitrosamine.

Previously, we demonstrated point mutations of the H-ras gene in N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT)-induced rat urinary bladder carcinomas. In this study, ras oncogene activation was examined in urinary bladder carcinomas induced by N-(4-hydroxybutyl)nitrosamine (BBN) or N-methyl-N-nitrosourea (MNU) administration followed by uracil treatment. In the first experiment, MNU (20 mg/kg body wt) was i.p. injected into 11 male F344 rats twice a week for 4 weeks, followed by feeding 3% uracil for 20 weeks (MNU/uracil group). Ten rats were given only 3% uracil without MNU pretreatment. In the second experiment, 20 male F344 rats were given 0.05% BBN in the drinking water for 4 weeks, then fed 3% uracil for 20 weeks (BBN/uracil group). Another 20 rats were fed 3% uracil without the BBN pretreatment. Transitional cell carcinomas were induced in the urinary bladder of all rats in the MNU/uracil and BBN/uracil groups. Papillomas and hyperplasias were present in the rats given uracil without prior BBN or MNU. DNA and protein were extracted from the tumors (MNU/uracil or BBN/uracil groups) or from the scraped bladder epithelium (uracil alone groups). Sequences around codons 12, 13 and 61 of H-, K- and N-ras genes were examined by direct sequencing after polymerase chain reaction, and p21 was examined by Western blotting. No mutation was found within the examined sequences and p21 showed no changes in mobility. There was no difference in the level of p21 expression between rats treated with MNU/uracil or BBN/uracil compared to corresponding uracil alone groups. These results indicate that the ras oncogene was not activated in urinary bladder carcinomas induced by BBN or MNU in combination with uracil treatment, in contrast to previous findings with FANFT.

Animals↗
PubMed1994

p53 mutation is infrequent and might not give a growth advantage in rat bladder carcinogenesis in vivo.

Abnormalities of the p53 gene are frequently observed in human tumors, including urinary bladder carcinoma, suggesting that p53 plays an important role in human carcinogenesis. However, its role in rat bladder carcinogenesis is unclear. In this study, we investigated the presence of p53 mutations in 122 urinary bladder tumors induced in F344 rats in the following carcinogenesis models: (i) 0.2% N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT; 6 weeks) in the diet followed by 3% or 5% sodium saccharin in the diet, 5% sodium ascorbate, 3.12% calcium saccharin (CaSac), 1.34% sodium chloride (NaCl), 5.2% CaSac plus 1.34% NaCl, or basal diet alone (72 weeks); and (ii) 0.2% FANFT, 0.05% N-(4-hydroxybutyl)nitrosamine in the drinking water, N-methyl-N-nitrosourea 20 mg/kg body wt, i.p. twice per week, or basal diet alone (4 weeks), followed by 3% uracil in the diet (20 weeks). Polymerase chain reaction-single-strand conformation polymorphism analysis and direct sequencing were performed for exons 5-8 in the rat p53 gene. We found nine tumors (7.4%) with p53 mutations. Two tumors had two mutations in the p53 gene. The tumors that had p53 mutations were relatively smaller than those that did not have p53 mutations. There were no mutation clusters among the treatments or hot-spots for p53 mutations. These results indicate that p53 mutation is infrequent in bladder carcinogenesis in rats, and when it does occur, it does not appear to provide a growth advantage.

Animals↗
PubMed1996

Rat liver epithelial cells express functional cytochrome P450 2E1.

Rat liver epithelial cells (RLECs) isolated by trypsinization of the livers of normal 10 day old rats are largely used in co-culture with primary hepatocytes. The aim of the present study was to investigate the expression of biotransformation enzyme-encoding genes in three preparations of RLEC lines. Although no expression of cytochrome P450 1A1/2 (CYP1A1/2), CYP2B1/2, CYP2C6 or CYP3A mRNAs could be detected, we found that all of the different preparations of RLECs expressed a high level of CYP2E1 mRNA. We demonstrated the presence of the CYP2E1 apoprotein in microsomes of RLECs by immunoblot analyses, together with chlorzoxazone 6-hydroxylation, an activity known to be mainly catalyzed by CYP2E1. In addition, acetone treatment of these cells resulted in an increase in both CYP2E1 apoprotein and chlorzoxazone 6-hydroxylation activity levels. Finally, we showed the susceptibility of RLECs to N-methyl formamide- and diethylnitrosamine-induced toxicity, suggesting metabolic activation by CYP2E1. Thus, RLECs may cooperate with hepatocytes to CYP2E1-mediated metabolism in the co-culture model. In addition, transfection experiments with a CYP2E1 promoter construct, in which the proximal 539 bp containing the binding site for HNF1alpha were inserted upstream of the chloramphenicol acetyl transferase gene, demonstrated a strong induction upon co-transfection with an HNF1alpha expression plasmid. Thus, RLECs provide a useful tool for studying metabolism and cytotoxicity of CYP2E1 substrates in the absence of other expressed CYPs, and for analyzing CYP2E1 promoter function.

Animals↗
PubMed1996

Analysis of differentiation-associated proteins in rat bladder carcinogenesis.

Uroplakins are the major integral membrane proteins synthesized in terminally differentiated, superficial urothelial cells. Alteration of cell differentiation during rat urinary bladder carcinogenesis was analyzed immunohistochemically for the expression of uroplakins. Expression of uroplakins was compared in N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT)-, uracil-, sodium saccharin- or sodium ascorbate-induced urothelial simple hyperplasia, papillary-nodular hyperplasia, papilloma and carcinoma. In controls, uroplakins were located only in superficial cells, especially the luminal surface membrane. In FANFT-induced hyperplasia, including simple hyperplasia, intermediate cells also stained and the staining pattern was disorderly and intermittent. In uracil-induced simple hyperplasia, intermediate cells were stained but in an orderly fashion. In sodium saccharin- or sodium ascorbate-induced simple hyperplasia, superficial cells were swollen but alterations were not observed in the staining pattern. In carcinoma induced by FANFT and uracil, uroplakin expression was very disorderly and focal, usually with no expression on surface cells. It appears that disorderly differentiation is an index of bladder malignancy and is an early event in FANFT-induced lesions but a late event in uracil-, sodium saccharin- and sodium ascorbate-induced lesions.

Animals↗
PubMed1984

A general probabilistic model of carcinogenesis: analysis of experimental urinary bladder cancer.

A theoretical model of two-stage carcinogenesis has been hypothesized. Variables that are modeled include the populations of normal, initiated, and transformed cells; mitotic rates of these cells; hyperplasia; and the probabilities of cell initiation and transformation during replication. The size of the cell populations can be estimated and mitotic rates determined directly from animal studies. Tumor occurrences at different time intervals following varying periods of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and sodium saccharin administration are known and are used in the indirect estimation of values for unobservable model variables. Model-based analyses suggest FANFT markedly increases the probability of cell initiation in addition to its experimentally verifiable effects on increasing the stem cell population and mitotic rates. Further, experimental results appear inconsistent with the hypothesis that FANFT increases the probability of cell transformation over background levels. Similarly, the effect of sodium saccharin was found to be attributable entirely to increases in stem cell populations and mitotic rates without influencing either the probability of initiation or the probability of transformation.

Animals↗
PubMed1986

Quantitative assessments of the cytotoxicity of bladder carcinogens towards cultured normal human uroepithelial cells.

Chemical carcinogens are known to exert cytotoxic effects on cells. The survival of cultured human uroepithelial cells (HUC) after exposure to several important classes of human and experimental animal bladder carcinogens has been quantitatively assessed in vitro using reduction in cell number and/or colony forming efficiency as the endpoint(s). Cells were treated with different carcinogens or various metabolites of a procarcinogen and the responses were analyzed with respect to the cell type used and to the donor source of the cells. The cytotoxic responses of HUC to the stable bladder procarcinogens tested [4-aminobiphenyl (ABP), 4-nitrobiphenyl, N-[4-(5-nitro-2-furyl)-2-thiazole]formamide and 2-amino-4-(5-nitro-2-furyl)thiazole] were dependent on both the concentration of chemical used and the duration of exposure. The survival of HUC after exposure to several metabolites of ABP differed. The N-hydroxylated derivatives of ABP (N-hydroxy-4-amino-biphenyl and N-hydroxy-4-acetylaminobiphenyl) were considerably more cytotoxic toward HUC than ABP or 4-acetylaminobiphenyl. The survival of HUC from different individuals after treatment with the direct acting carcinogen N-nitro-N-methylurea was very similar. In contrast, the survival of HUC from different donors varied considerably after treatment with the procarcinogen 3-methylcholanthrene which requires metabolic activation. However, significant heterogeneity in the survival of HUC from five donors after exposure to the human bladder procarcinogen ABP was not observed in this study. Cultures of normal human fibroblasts from four donors showed an unexpected heterogeneous response to the cytotoxic effects of ABP. These results demonstrate that many variables affect the cytotoxic response of normal cells to bladder carcinogens.

Aminobiphenyl Compounds↗
PubMed1986

Mutagenicity of 3,4-diphenyl-5-nitrofuran analogs in Salmonella typhimurium.

A new series of chemicals comprising eight different 3,4-diphenyl-substituted furan analogs, namely, methyl-3,4-diphenyl-2-furoate, methyl-3,4-diphenyl-5-nitro-2-furoate, 3,4-diphenyl-5-nitro-2-furoic acid, 3,4-diphenyl-5-nitro-2-acetylfuran, 3,4-diphenyl-5-nitro-2-bromoacetylfuran, 2-amino-4-(3,4-diphenyl-5-nitro-2-furyl)thiazole, 2-acetyl-amino-4-(3,4-diphenyl-5-nitro-2-furyl)thiazole and 2-formyl-amino-4-(3,4-diphenyl-5-nitro-2-furyl)thiazole were synthesized and their mutagenic activities tested in Salmonella typhimurium. The structure--activity relationship studies revealed that for mutagenic activity the nitro group is essential and that the potency of activity is greatly altered by the nature of the substituent at the 2-position of the furan ring. The mutagenic activities of these chemicals were generally much higher in TA100 compared to TA98. The relative order of activities for 2-substituted, 3,4-diphenyl-5-nitrofurans were COOCH3 greater than COCH2BR greater than COCH3 greater than COOH in S. typhimurium TA100. 3,4-Diphenyl-5-nitro-2-bromoacetylfuran was equally active in nitroreductase-proficient (TA98, TA100) and in nitroreductase-deficient (TA98NR, TA100NR) strains. In contrast, the acetyl and carboxymethyl ester analogs were relatively less active in nitroreductase-deficient strains. Mutagenic activities of 3,4-diphenyl-substituted furylthiazoles in comparison with the unsubstituted analogs of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide, N-[4-(5-nitro-2-furyl)-2-thiazolyl]-acetamide and 2-amino-4-(5-nitro-2-furyl)thiazole revealed that the phenyl groups drastically reduced their mutagenic activities. However, the relative order of activities formylamino greater than or equal to acetylamino greater than amino were the were the same between phenyl-substituted and unsubstituted analogs.

Biotransformation↗