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G T Bryan

Publications and source records attributed to G T Bryan.

At least 55 records · Page 3Linked to original sources
PubMed1985

Tumor promoter 12-O-tetradecanoylphorbol-13-acetate receptors in normal human transitional epithelial cells.

As a prelude to study the promotion with TPA of in vitro transformation of human urothelial cells (HUC) in culture, we characterized tumor promoter TPA receptors in primary cultures of HUC. [3H]TPA bound specifically to intact living HUC; maximum specific binding was attained in approximately 30 min at 37 degrees C. [3H]TPA bound to HUC in a saturable and competitive manner. Scatchard analysis of specific binding to intact cells displayed a single slope corresponding to an equilibrium dissociation constant (Kd) of 0.56 nM; at saturation TPA-binding capacity was 2.37 pmol/10(6) HUC (1.43 X 10(6) sites per cell). [3H]TPA bound specifically and with high affinity to the particulate fractions of HUC; binding was both saturable and reversible. Saturation of the specific binding of [3H]TPA occurred at approximately 1 nM at 4 degrees C. Scatchard analysis of specific binding to the particulate fraction displayed a single slope corresponding to a Kd of 1.08 nM; at saturation TPA-binding capacity was 2.05 pmol/mg protein (750 000 molecules per HUC). [3H]TPA binding was inhibited by the biologically active phorbol ester, phorbol didecanoate, whereas inactive phorbol did not compete for TPA binding. Binding was not affected by sodium saccharin, epidermal growth factor, retinoic acid or dexamethasone. [3H]TPA bound specifically to the HUC cytosolic fraction but only in the presence of calcium and phosphatidylserine. Calcium-activated and phospholipid-sensitive protein kinase activity was detected in HUC fractions. These results indicate the presence of high-affinity specific receptors for TPA in HUC.

Caenorhabditis elegans Proteins↗
PubMed1985

Antitumor effects of polyribonucleotides for mouse transitional cell carcinoma enhanced by cyclophosphamide.

Mouse bladder tumor (MBT-2), derived from a carcinogen-induced transitional cell carcinoma of the bladder, has proven a useful model for study of pathogenesis and prediction of cytotoxic drug sensitivity of human bladder carcinoma. To define optimal conditions for activity of the potent interferon inducer polyriboinosinic-polyribocytidylic acid [poly(I) X poly(C)] in this model, studies of dose, timing, and combinations with a cytotoxic drug were initiated. Poly(I) X poly(C) inhibited MBT-2 growth when 10(5) or 10(6) tumor cells were implanted. Tumor growth reduction was relatively more pronounced in mice inoculated with higher numbers of MBT-2 cells (10(6] than in mice inoculated with an intermediate dose (10(5] or small dose (10(4]. In mice inoculated with 10(5) MBT-2 tumor cells, poly(I) X poly(C) (2.5 or 10 mg/kg i.p.) on Days 5 to 19 every other day reduced tumor size markedly. It had no effect, however, on tumor incidence or the time of their first detection. Treatment for a shorter period (alternate days from Days 11 to 19) resulted in less inhibition of tumor growth. Once treatment was discontinued, tumors grew progressively. Polyriboadenylic:polyribouridylic acid [poly(A) X poly(U)] (10 mg/kg) which inhibited tumor growth but to a lesser degree than poly(I) X poly(C) induced lower, less sustained levels of serum interferon. Cyclophosphamide, injected i.p. on Day 1, resulted in inhibition of tumor incidence and growth in direct proportion to the dose administered (25 to 200 mg/kg), but it was curative only at greater than or equal to 30% lethal doses. When combined with poly(I) X poly(C) (2.5 or 10 mg/kg), cyclophosphamide (50 mg/kg) had an additive antitumor effect. Optimal inhibition of MBT-2 tumor growth occurred by combining cyclophosphamide (100 mg/kg) with poly(I) X poly(C) (2.5 mg/kg); eight of 14 mice were tumor free on Day 60.

Animals↗
PubMed1984

Tumor production in germ-free rats fed 5-nitrofurans.

Weanling female germ-free Sprague-Dawley rats were divided into 3 groups: the control group rats were fed an autoclaved 5010C diet for 2 years; the nitrofurantoin (NF) group rats were fed this diet supplemented with 0.188% NF for 2 years; and the N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT) group rats were fed this diet supplemented with 0.188% FANFT for 20 weeks followed by 20 additional weeks of the control diet. The FANFT-group rats were killed following the early appearance of bladder tumors. Six of 11 control rats had tumors: 2 with mammary fibroadenomas, 1 with adrenal adenoma, 1 with leukemic spleen, and 2 with mesenchymal sarcoma of the colon. Ten of 12 NF-group rats had tumors: 9 with mammary fibroadenomas, 1 with adrenal adenoma, and 1 each with leukemic spleen and cervical squamous cell carcinoma. Eight of 12 FANFT-group rats had tumors: 7 with bladder and 1 with renal pelvis transitional cell carcinoma. The incidences of mammary fibroadenoma in the NF group and of lower urinary tract tumors in the FANFT group were significantly greater (P less than 0.01) than those of these tumors in the control group.

Animals↗
PubMed1984

Antiproliferative activities of interferons against human bladder carcinoma cell lines in vitro.

The antiproliferative effect of interferons against 5 human bladder carcinoma cell lines, RT112, T24, RT4, 647V and HT1197, was determined in vitro. Each of these human bladder carcinoma cell lines except 647V was sensitive to human interferons in liquid media. The antiproliferative effect of interferons was observed only upon continuous exposure, not after 1 hour. Partially purified, naturally produced interferon beta was more inhibitory of cell growth than naturally produced interferon alpha. Interferon alpha 54, 76, 61, 6L and 1 purified to homogeneity were as effective as naturally produced, partially pure interferon alpha. Although interferon beta, produced by recombinant DNA technology and purified to homogeneity, was not equivalent in effectiveness to naturally produced interferon beta, its antiproliferative activity was greater than interferon alpha 54 for 3 of 4 cell lines tested. Antimitotic effects may underlie, at least in part, the potential therapeutic activity of interferons for bladder carcinoma.

Carcinoma, Transitional Cell↗
PubMed1984

Bioconversion and macromolecular binding of 2-amino-4-(5-nitro-2-furyl)thiazole by cultured rat urothelial cells.

Bioconversion and binding of 2-amino-4-(5-nitro-2-furyl)-thiazole (ANFT) were examined using cultured rat bladder epithelial cells from weanling male F344 rats. Bladder cells were obtained in large quantities from outgrowths of dissected explants which were grown on collagen gels. Metabolic potential of rat urothelial cells to activate ANFT was evaluated by incubating primary culture cells with [2-14C]ANFT for 48 hr. Metabolites were subsequently analyzed by chromatographic and spectroscopic methods. Thin-layer chromatography of the ethyl acetate:diethyl ether (1:1, v/v) extract of the culture medium revealed two regions of radioactivity with Rf values of 0.12 and 0.60, the former corresponding to ANFT and the latter to one of its metabolites. High-pressure liquid chromatography of the solvent extract revealed two major peaks, with retention times of about 4 and 9 min, corresponding with the metabolite and ANFT, respectively. Low-resolution mass spectrum of the isolated metabolite showed a molecular ion at m/e 181. The metabolite was identified as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone based on its chromatographic and spectral characteristics in comparison with the synthetic compound. About 24% of the recovered radioactivity from the culture medium was extractable into the organic phase, a majority of which was identified as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone. Analysis of binding to proteins and nucleic acids prepared following exposure of [2-14C]ANFT revealed a 15- and 9-fold greater amount of binding, respectively, in cultures incubated with bladder cells than their corresponding heat-inactivated controls. Furthermore, homogenates of cultured bladder cells reduced ANFT on anaerobic incubation with reduced nicotinamide adenine dinucleotide phosphate to generate 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone. On reduction of [2-14C]ANFT with rat bladder or liver homogenates, about 23 and 11%, respectively, of the initial amounts of radioactivity were bound to the trichloracetic acid-insoluble fraction. These data demonstrate that rat bladder cells possess the metabolic capability to reduce ANFT and to generate reactive intermediate(s) that bind to cellular macromolecules.

Animals↗
PubMed1984

Augmented antiproliferative effects of interferons at elevated temperatures against human bladder carcinoma cell lines.

The in vitro antiproliferative effects of interferons (IFN) against the human bladder carcinoma cell lines T24, RT4, HT1197, and 647V were evaluated at temperatures ranging from 37-41 degrees. At 37 degrees, the antiproliferative activities of IFN, either naturally produced or produced by recombinant DNA technology, were different against different cell lines. An increase in temperature markedly enhanced the antimitotic effect of IFN for all cells. For example, T24 cells grown at 37 degrees and treated with 200 units naturally produced IFN-alpha or IFN-beta per ml for 7 days were inhibited 50 to 60%. No change in cell proliferation occurred in untreated T24 cells grown at 39.5 degrees. Treatment with 200 units IFN-alpha or IFN-beta per ml at 39.5 degrees inhibited these cells 80 to 90%. Similar results were obtained with IFN produced by recombinant DNA technology and purified to homogeneity. Colony formation by the RT4 cell line, at 37 degrees, was decreased less than 10% with 200 units IFN-alpha per ml and 63% by 200 units IFN-beta per ml. At 39.5 degrees, colony formation by untreated RT4 cells was inhibited 48%. Treatment with IFN-beta at 39.5 degrees did not result in an enhancement of the antiproliferative effect; however, treatment with IFN-alpha enhanced the inhibition from less than 10% to 98%. These results suggest that a supraadditive relationship exists between antiproliferative effects of IFN and temperature elevation. The differences seen between IFN-alpha and IFN-beta may be due to the different stabilities of these two molecules. In order to probe the mechanism of the enhanced antiproliferative effect, activity of an IFN-induced enzyme, 2'-5'-oligoadenylate synthetase, was measured. IFN-alpha treatment resulted in significantly greater 2'-5'-oligoadenylate synthetase induction at 39.5 degrees than at 37 degrees. Thus, two cellular effects resulting from IFN were augmented by increased temperature.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

Biotransformation of the bladder carcinogen N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide in mice.

The biotransformation of N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT), a potent urinary bladder carcinogen, was studied in mice. About 82% of radioactivity was excreted as 14CO2 within 36 hr after intragastric administration of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-[14C]formamide, suggesting its deformylation to 2-amino-4-(5-nitro-2-furyl)thiazole ( ANFT ). The latter was formed in vitro as a product following incubation of FANFT with mouse liver homogenates. Chromatographic analysis of mouse urine obtained 24 hr after the i.p. administration of N-[4-(5-nitro-2-furyl)-[2-14C]thiazolyl]formamide revealed excretion of ANFT and unmetabolized FANFT, suggesting the prevalence of the deformylation reaction in vivo. In addition, at least two more metabolites were present in urine. One of these metabolites exhibited chromatographic properties similar to those exhibited by a compound derived from the in vitro nitroreduction of ANFT . This metabolite was isolated from urine of FANFT-fed animals and from in vitro enzymatic reduction of ANFT with mouse liver homogenates. The isolated products had chromatographic and spectral properties and a mass spectral fragmentation pattern similar to that of a compound obtained by catalytic reduction of ANFT with palladium and activated carbon. Spectroscopic analyses established the structural identity of the chemical reduction product as 1-[4-(2-aminothiazolyl)]-3-cyano-1-propanone ( ATCP ). Since the chromatographic properties of the enzymatically derived product and the urinary metabolite were identical to those of a compound obtained by chemical reduction, they must be structurally the same and thus correspond to ATCP . About 5% of the urinary metabolites of FANFT is ATCP , and thus ATCP is quantitatively a minor excretory product. ATCP was far less active than was ANFT of FANFT in the Ames mutagenicity assay with Salmonella typhimurium TA.

Animals↗
PubMed1984

Stimulation of ornithine decarboxylase activity and DNA synthesis by phorbol esters or bile acids in rat colon.

The changes of colonic epithelial ornithine decarboxylase (ODC) activity and DNA synthesis following intrarectal administration of a tumor-promoting agent, 12-O-tetradecanoylphorbol-13-acetate (TPA), or various bile acids to male noninbred rats were studied. A single instillation of TPA, at a dose as low as 16 nmol, led to a significant (about 10-fold) increase in colonic ODC activity. Peak ODC activity was observed at 4 hr, and the enzyme activity returned to the control level about 24 hr after intrarectal TPA. This pattern was almost the same as that observed after sodium deoxycholate treatment. TPA showed more potent induction of ODC activity than deoxycholate, although the maximal induction was greater in the case of deoxycholate treatment. Both TPA and deoxycholate stimulated DNA synthesis at 2 days after intrarectal instillation, after an initial depression at 4-12 hr. A structure-activity study of 26 bile acids revealed that 5 beta-cholanoic acid with alpha-hydroxy groups in two of the 3 alpha, 7 alpha, 12 alpha positions and 5 beta-cholanoic acid with a 3 alpha-hydroxy group induced colonic ODC activity significantly, while the 3 alpha, 6 alpha-dihydroxy acid did not. Replacement of hydroxy groups by keto groups or a change from alpha to beta configuration decreased the ODC-inducing activities. Tri-substituted 5 beta-cholanoic acid derivatives, whether hydroxy or keto, did not stimulate ODC. These data indicate that a specific bile acid structure with a definite spatial relationship of the hydroxy groups is required for induction of colonic ODC activity.

Animals↗
PubMed1983

Growth and characterization of normal human urothelium in vitro.

A method for initiating rapidly growing cultures of normal human transitional cells from ureter and embryonic bladder specimens has been developed and quantified. A new microdissection technique was used to nonenzymatically separate the urothelium. The use of enriched medium containing 10 micrograms/ml insulin, 5 micrograms/ml transferrin, and 1 microgram/ml hydrocortisone resulted in improved growth. The use of thin collagen gel substrates (0.6 ml/60 mm petri dish) resulted in 97% attachment of explants compared to 77% attachment on plastic. Explants grown on thicker collagen (2 ml/60 mm petri dish) showed, in addition to better attachment, enhanced growth of cells as determined both by measurements of colony size and cell density. Cultures of transitional cells that were initiated using explants could be passed three to five times using 0.1% EDTA for dispersion. Autoradiography of [3H]thymidine-labeled cells showed an initial phase of rapid cell division in primary explant cultures and restimulation of cell division in passaged cultures. Transmission electron microscopy showed that the cells growing out from the explants were continuous with the stratified urothelium maintained in the original explant. Stratification of transitional cells occurred in cultures of both ureter and embryonic bladder cells. Surface cells were joined near their apices by junctional complexes. Desmosomes and Golgi vesicles were present in all cells. Passage in culture did not alter the morphological characteristics of cells.

Cell Division↗
PubMed1983

Pathogenesis of human urinary bladder cancer.

The pathogenesis of bladder cancer is being analyzed at several levels of biological organization, i.e., population groups, individual whole animal, tissue, cell, molecule, etc. Each of these levels provides opportunities for mechanistic studies. Yet the integration of these several levels into a cohesive fabric is incomplete. From a clinical point of view, the following seem of importance to human bladder cancer pathogenesis. The initiation, promotion, and progression of bladder cancer involves several factors acting concurrently or sequentially. These factors appear to be naturally occurring or synthetically created chemicals present in the external environment. Human exposures to these agents may begin in utero, and varying, dynamic qualitative and quantitative exposure patterns continue through developmental and adult life. Apparent latent periods of development of clinical bladder cancer may be as short as one, or as long as 50 years or more. Individuals may exhibit differential susceptibility to vesical carcinogens, perhaps through phenotypic differences in quantitative biotransformation routes. Differences in bladder epithelial cell susceptibilities probably also occur, as well as varying local tissue and generalized resistance to neoplasia formation. Older individuals do not appear to be more resistant to bladder carcinogenesis. A number of animal model systems have been developed for the study of the in vivo, cellular, and molecular pathogenesis of bladder cancer. These models replicate many of the known salient features of human bladder cancer. Through use of appropriate whole animal models in conjunction with investigations of human and animal bladder cells and tissues in culture, controlled mechanistic and quantitative studies of bladder cancer pathogenesis should rapidly develop.

Amines↗
PubMed1983

Specific binding, stimulation of rodent urinary bladder epithelial ornithine decarboxylase, and induction of transitional cell hyperplasia by the skin tumor promoter 12-O-tetradecanoylphorbol-13-acetate.

The effects of intraurethral or i.p. administration of a mouse skin tumor promoter phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), on rodent urinary bladder transitional epithelium were studied. TPA, when instilled into the urinary bladder of inbred rats (female Fischer, F344) or mice (C3H, ICR, C57BL X DBA/2 F1) at a dose as low as 0.16 nmol, led to a significant (about 10-fold) increase in bladder ornithine decarboxylase (EC 4.1.1.17) (ODC) activity. Peak ODC activity was observed at about 6 hr, and enzyme activity returned to base levels about 14 hr after intravesical TPA. Administration of TPA i.p. in dimethyl sulfoxide also induced vesical ODC at 4 hr after treatment. The magnitude of vesical ODC induction correlated well with the ability of a series of phorbol esters to promote mouse skin tumor formation (TPA greater than phorbol didecanoate greater than phorbol dibenzoate, and phorbol diacetate or phorbol did not induce bladder ODC activity). Mezerein, a second stage mouse skin tumor promoter, induced urinary bladder ODC as much as TPA did. Increased ODC activity by TPA was the result of an increased amount of ODC protein localized mostly (greater than 60%) in urinary bladder mucosa. Intraurethrally administered TPA induced transitional cell hyperplasia starting at Day 2, and it persisted for about 7 days. The urothelium regained normal histology 13 days after TPA treatment. TPA bound specifically and with high affinity to murine bladder mucosa and muscularis particulate preparations. Scatchard analysis of mucosal binding revealed a Kd of 0.82 nM; at saturation, 2.43 pmol were bound per mg protein. Since TPA binds specifically to urinary bladder epithelium, and the induction of ODC activity is one of the properties of tumor promoters, one may conclude that TPA may promote urinary bladder carcinogenesis. Intravesical saccharin also induced urinary bladder ODC activity, but TPA at equimolar quantity was far more potent than saccharin. Thus TPA, being a structurally well-defined molecule, may be a useful compound to study the phenomenon of the tumor promotion stage in urinary bladder carcinogenesis.

Animals↗
PubMed1983

Azathioprine induction of lymphomas and squamous cell carcinomas in rats.

The carcinogenicity of azathioprine was evaluated in weaning female noninbred Sprague-Dawley rats by feeding it in the diet. Due to toxicity, the dose had to be changed during the course of the experiments and ranged from 0.015 to 0.04% of the diet by weight. In the first experiment, the estimated maximal cumulative consumption of azathioprine was 1.5 g/rat. Of the 14 rats evaluated, six developed thymic lymphomas, and four developed squamous cell carcinomas of the ear duct. When the experiment was repeated with a slightly lower daily consumption but with a cumulative total dose of 2.2 g/rat, there were seven of 19 rats with thymic lymphoma and two rats with ear duct carcinoma. These data support the hypothesis that azathioprine is a carcinogen.

Animals↗
PubMed1983

Altered growth patterns in vitro of human papillary transitional carcinoma cells.

In vitro growth patterns and morphologic characteristics of five low-grade human papillary transitional cell carcinomas (TCCs) were compared and contrasted with those of normal human urothelial cells in culture. Biopsies of TCC were performed by transurethral resection. Specimens of normal human ureters were obtained surgically. Singly dispersed TCC cells grew in 0.3% agarose semisolid medium with a cloning efficiency ranging from 0.02% to 0.71%. Singly dispersed normal ureteral urothelial cells under the same conditions did not form colonies in 0.3% agarose. Neither singly dispersed TCC nor normal urothelial cells formed colonies when plated on collagen-gel substrates. In primary explant culture, normal human urothelial cells grew rapidly, to form tightly adherent flat sheets of apparently nonmotile cells. Autoradiographic labeling with 3H-thymidine of growing cultures of normal urothelial cells showed cell division primarily in the zones of growth near the explant. Outgrowth of TCC from primary explants was loosely adherent. One TCC explant culture gave rise to a continuous suspension culture. Numerous multilayered cellular formations of fronds, nodules, and "walls" were seen around the periphery of TCC explant colonies. Autoradiography showed that these multilayered areas of TCC growth contained actively dividing cells. The altered ability of papillary TCC to form superficial multilayered formations in vitro distinguishes them from normal human urothelium and reflects the morphologic characteristic of this tumor type in vivo.

Adolescent↗
PubMed1982

Epidemiology of hexachlorobenzene-induced porphyria in Turkey: clinical and laboratory follow-up after 25 years.

Cutanea tarda and mixed porphyric symptoms resulted from accidental ingestion of hexachlorobenzene (HCB)-treated seed grain in Turkey 25 years ago and involved about 4,000 persons with a 10% mortality. Twenty-five years later, 161 patients, 63 women and 98 men, with histories of HCB exposure as children or young adults were studied. Many patients had persistent abnormal porphyrin metabolism and prominent neurological, dermatologic, and orthopedic symptoms and signs. Thyromegaly was seen in 60% of the women and 27% of the men. The children born to porphyric mothers 25 years ago all died of pembe yara secondary to maternal milk and transplacental transfer of HCB. Current lactation specimens of porphyric patients show high HCB levels, up to 3.12 ppm, but the infant offspring appear normal.

Adult↗
PubMed1982

Influence of non-specific immunologic factors on prognosis in advanced bronchogenic carcinoma.

Fifty-nine evaluable patients with stage III bronchogenic carcinoma, participating in a randomized clinical trial evaluating the effect of adjuvant immunotherapy with levamisole or BCG in the treatment of clinically advanced lung cancer, were studied for their immunocompetence by in vitro and in vivo assays. Immunological tests consisted of measurements of natural killer (NK) cell and killer (K) cell cytotoxicity, skin testing reactivity to recall antigens, absolute lymphocyte count, and serum immunoglobulin (Ig) levels. Pretherapy K cell cytotoxic levels, skin test reactivity to trichophyton antigen, and increased IgA levels were predictive of the overall clinical course. Despite non-specific immunotherapy, progressive decline of NK and K cell cytotoxicity occurred during the course of the disease. These findings, however, were of limited clinical value. Initial performance status and disease extent significantly influenced time to progression and survival. Little further prognostic information was obtained from the immunological tests over those provided by clinical performance status and disease extent. No statistically significant differences were found in either time to progression or survival between controls and patients receiving either levamisole or BCG.

Carcinoma, Bronchogenic↗