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Biomedical subjects

L Diamond

Publications and source records attributed to L Diamond.

At least 91 records · Page 5Linked to original sources
PubMed1983

Effects of the Clara cell toxin, 4-ipomeanol, on pulmonary function in rats.

The naturally occurring compound, 4-ipomeanol (IPO, 1-[3-furyl]-4-hydroxy-1-pentanone), selectively damages the nonciliated epithelial (Clara) cells of the terminal bronchioles. Because information is not available concerning functional changes in IPO-treated lungs, an investigation was undertaken to evaluate the in vivo pulmonary ventilatory, mechanical, and gas exchange functions of female Long-Evans rats 24 h after treatment with a single intraperitoneal dose of 1 or 5 mg IPO/kg body wt. A preliminary toxicity study established the 24-h LD50 for intraperitoneally administered IPO at 19 +/- 3 (SD) mg/kg. Significant increases in lung fluid occurred in animals treated with 15 mg IPO/kg, and histological evidence of pulmonary edema was observed in animals treated with 10 mg IPO/kg. Treatment of rats with 5 mg IPO/kg caused a significant decrease in tidal volume and a significant increase in respiratory rate and functional residual capacity-to-total lung capacity ratio (%). In rats treated with 1 mg IPO/kg, pulmonary functions were minimally affected. The functional changes observed in IPO-treated animals can be attributed to swelling and possible dysfunction of Clara cells, with subsequent alveolar interstitial edema and stimulation of juxtapulmonary capillary receptors, or to a direct effect of the toxin on respiratory control mechanisms.

Animals↗
PubMed1983

In vivo bronchodilator activity of vasoactive intestinal peptide in the cat.

Vasoactive intestinal peptide (VIP) is an octacosapeptide that occurs widely in the animal kingdom, is distributed in many organs and tissues, and has a broad range of biologic actions. We evaluated the ability of VIP to produce bronchodilation in anesthetized, mechanically ventilated, atropinized, closed chest cats. Boluses of VIP injected intravenously (0.1 to 10 micrograms X kg-1) reversed in a dose-dependent manner the increase in lung resistance (RL) and the decrease in dynamic lung compliance (Cdyn) induced by an intravenously administered infusion of 5-hydroxytryptamine (5HT) (5 to 30 micrograms X kg-1 X min-1). Distribution of bronchodilator activity was assessed by using RL as an index of central airways caliber and dynamic elastance (Edyn; the inverse of Cdyn) as an index of tone in peripheral airways and lung parenchyma. Although all levels of the tracheobronchial tree responded to VIP, the predominant site of action appeared to be in central airways. A similar distribution and magnitude of relaxant effects were observed after the intravenous administration of prostaglandin E2 (PGE2) (0.1 to 10 micrograms X kg-1). Prostaglandin E2 also was effective in reversing 5HT-induced bronchoconstriction when given by ultrasonic nebulization, whereas VIP was not. Bronchodilation mediated by VIP persisted after pretreatment with indomethacin or propranolol. We conclude that VIP is a potent relaxant of feline airways smooth muscle in vivo and that this effect of the peptide occurs independent of prostaglandin production or beta adrenergic receptor activation.

Animals↗
PubMed1983

Benzo(a)pyrene and 7,12-dimethylbenz(a)anthracene metabolism and DNA adduct formation in primary cultures of hamster epidermal cells.

Primary cultures of hamster epidermal cells exposed to hydrocarbon, 1 microgram/ml, rapidly metabolized [3H]benzo(a)pyrene and [14C]7,12-dimethylbenz(a)anthracene to ethyl acetate:acetone- and water-soluble metabolites. By 24 hr, only 13.6% of the organic solvent-soluble radioactivity recovered in the medium was unchanged [3H]benzo(a)pyrene, and only 5.9% was unchanged [14C]7,12-dimethylbenz(a)anthracene. With both hydrocarbons, the major water-soluble metabolites found extracellularly were conjugated with glucuronic acid; these were primarily phenolic derivatives. Metabolites cochromatographing with 7,8-dihydro-7,8-dihydroxybenzo(a)pyrene or trans-3,4-dihydro-3,4-dihydroxy-7,12-dimethylbenz(a)anthracene were not detectable in high-pressure liquid chromatographic profiles of organic solvent-soluble intracellular and extracellular metabolites. However, analysis of [3H]benzo(a)pyrene: and [3H]7,12-dimethylbenz(a)anthracene: DNA adducts indicated that these putative proximate carcinogenic metabolites were formed in these cells and subsequently metabolized to DNA-binding products. The results suggest that metabolic incompetence may not be an explanation for the relative resistance of the hamster to epidermal carcinogenesis by polycyclic hydrocarbons.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Mutagenesis in Chinese hamster cells by cyclopenta(a)phenanthrenes activated by a human hepatoma cell line.

The cyclopenta(a)phenanthrene, 15,16-dihydro-11-methyl-cyclopenta(a)phenanthren-17-one, had potent mutagenic activity in cell-mediated mutation assays with V79 Chinese hamster cells as targets, and cells of the human hepatoma line HepG2 as mediators of activation. The compound was inactive when low-passage hamster embryo cells were used as activators. When the mutagenic activity of a series of cyclopenta(a)phenanthrenes was compared in mutation assays with HepG2 cells as activators, there was a good correlation between mutagenic activity in this system and carcinogenic activity in mouse skin in vivo. One exception was a noncarcinogenic compound, which is mutagenic in the Ames' test, and was also mutagenic in the mammalian cell assay.

Animals↗
PubMed1983

Ornithine decarboxylase activity and DNA synthesis in primary and transformed hamster epidermal cells exposed to tumor promoter.

To better understand the progression of epithelial cells from a normal to a malignant phenotype, we have compared various responses of normal, preneoplastic, and neoplastic hamster epidermal cells to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). TPA, but not fresh serum-containing medium, induced ornithine decarboxylase (ODC) activity in primary hamster epidermal cells; the combination of TPA and medium was no more effective than was TPA alone. In four epidermal cell lines derived after treatment of cultures with carcinogen, the pattern of ODC induction at low passage levels was similar to that observed in primary cells. However, by the time the cell lines had become anchorage independent or formed tumors in appropriate hosts, the effect of TPA and fresh medium on ODC activity was synergistic. TPA did not affect the growth rate, plateau density, cellular morphology, or size of either primary epidermal cultures or continuous cell lines. Incorporation of [3H]thymidine by primary epidermal cells and some, but not all, cell lines was stimulated by addition of fresh medium but inhibited by TPA alone. In combination with fresh medium, however, TPA potentiated [3H]thymidine incorporation. We conclude that hamster epidermal cell lines acquire a characteristic synergistic induction of ODC activity by TPA and fresh medium as they progress toward malignancy. However, no consistent alteration is observed with respect to the parameters of mitogenesis examined.

Animals↗
PubMed1982

The effect of liver homogenate (S20) concentration on polycyclic aromatic hydrocarbon activation and mutation induction in the L5178Y mouse lymphoma mutation assay.

Hydrocarbon activation and mutation induction in the L5178Y mouse lymphoma mutation assay were studied as a function of the concentration of an exogenously added rat liver homogenate activation system (S20). Four polycyclic aromatic hydrocarbons were tested at constant dosage levels with 4 concentrations of S20 for ability to induce forward mutations at the thymidine kinase (TK) locus. With all 4 hydrocarbons, increasing S20 concentration resulted in a significant (p less than 0.001) decrease in mutation frequency and corresponding increase in survival. In the absence of S20, no significant mutation induction was observed. Within 5 min after the addition of S20 to a reaction mixture containing [3H]benzo[a]pyrene [B(a)P] (3 micrograms/ml) and appropriate cofactors, 70% of the B(a)P was metabolized with a high S20 concentration, whereas only 14% was metabolized with a low S20 concentration. In the absence of S20, the cells did not metabolize B(a)P. Incubation of B(a)P with a low concentration of S20 in the presence of calf thymus DNA (1.5 mg/ml) resulted in twice as much covalently bound B(a)P per mg DNA (33 pmoles/mg) as incubation with a high concentration of S20 (15 pmoles/mg). The amount of the major B(a)P-DNA adduct, (+/-)-7 beta,8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene-deoxyguanosine, per mg DNA was 5 times greater with low S20 concentration than with high (11.6 pmoles/mg and 2.1 pmoles/mg, respectively). These results suggest that the decrease in mutation frequency with high S20 concentrations results from the rapid oxidation of the hydrocarbon which reduces the opportunity for mutagenic derivatives that are formed from B(a)P to interact with DNA and induce mutation.

Animals↗
PubMed1982

Expression time for benzo[a]pyrene-induced 6-thioguanine-resistant mutations in V79 Chinese hamster cells.

The effect of expression time (the time between the end of the treatment period and the first exposure to selective medium) on the frequency of benzo[a]pyrene (BP)-induced mutations at the HGPRT (hypoxanthine-guanine phosphoribosyl transferase 2.4.2.8) locus was examined in the cell-mediated mutation assay in which V79 Chinese hamster cells are the targets and BP activation is mediated by Syrian hamster embryo cells. After the optimal expression time (4-5 days), the mutation frequency induced by exposure to 0.5 microgram BP/ml decreased logarithmically with increasing length of expression time until at 40 days there was a complete absence of mutant cells. The growth rates of three BP-induced 6-thioguanine-resistant clones were examined; each of these clones had a 30% longer lag time before reaching the period of logarithmic growth than the parent V79 cells. This suggests that the decay in mutation frequency with increasing expression time may be due to the slower reinitiation of growth by mutant than non-mutant cells after subcultivation into non-selective medium; this results in a loss of 25-40% of the mutant cells with each subculture. These findings show that optimal expression time in cell-mediated mutation assays may be of short duration and that this must be taken into account in the design and interpretation of such assays.

Animals↗
PubMed1982

Metabolism of benzo[a]pyrene by fish cells in culture.

Benzo[a]pyrene (BaP) metabolism was studied in cell lines derived from rainbow trout (RTG-2), bluegill fry (BF-2), and fathead minnow (FHM). Confluent cultures were exposed to 3H-BaP (0.5 nmol/ml), and, after various exposure times, metabolites were extracted from the media with an organic solvent and analyzed by high-pressure liquid chromatography. BF-2 and RTG-2 cells converted 63% of the BaP to water-soluble metabolites within 24 h, while FHM cells converted only 12%. BF-2 and RTG-2 cells metabolized more than 90% of the BaP by 48 h, while only 67% of the BaP was converted to water-soluble metabolites by FHM cells after 96 h. The major organic-solvent-extractable metabolites in all three cell lines were 9,10-dihydroxy-9,10-dihydrobenzo[a]pyrene and unidentified polar metabolites. Of the water-soluble metabolites formed by BF-2, FHM, and RTG-2 cells, 67, 42, and 19%, respectively, were converted to ethyl-acetate-extractable metabolites by treatment with beta-glucuronidase. All three cell lines formed a glucuronide of 7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (7,8-diol); in BF-2 and FHM cells, the 7,8-diol represented almost half of the metabolites released by beta-glucuronidase treatment. Thus, cell lines derived from three widely distributed species of freshwater fish have the capacity to metabolize BaP to a form that is a proximate carcinogen in rodents and to produce a water-soluble conjugate of this metabolite.

Animals↗
PubMed1982

Benzo[a]pyrene--DNA adduct formation in target cells in a cell-mediated mutation assay.

In order to analyze the adducts formed in V79 Chinese hamster target cells in a Syrian hamster embryo (HE) cell-mediated mutation assay, a procedure was developed in which the HE cells are differentially killed when the mixed cell suspension is treated with antiserum to Syrian HE cells and complement. The V79 cell suspension, separated from lysed HE cells by gradient centrifugation, is greater than 90% HE cell-free. When the carcinogen--DNA interaction products formed in these two cell types were analyzed after exposure to [3H]benzo[a]pyrene (B[a]P) for 24 h under the conditions of a cell-mediated mutation assay, the major B[a]P--DNA adducts in both cell types resulted from reaction of the anti and syn isomers of B[a]P-7,8-diol-9,10-epoxide with DNA. The amount of B[a]P bound/mg DNA in the target cells was only 30% less than in the activator cells, and the relative proportions of the adducts of the syn and anti isomers were similar in the two cell types. The target cells, which do not metabolize B[a]P, were also unable to metabolically activate B[a]P-7,8-diol to DNA-binding metabolites. Thus, the transfer of activated B[a]P metabolites from activator cells to the DNA of target cells is a relatively efficient process that appears to be independent of the relative reactivity of specific metabolites with cellular nucleophiles. The immunological cell separation procedure we describe can be adapted to the analysis of carcinogen--cell interaction products formed in cell-mediated assays in which other types of activator and target cells are used to measure either mutation or another biological endpoint.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1982

Tumor-initiating activity of 4-fluoro-7,12-dimethylbenz[a]anthracene and 1,2,3,4-tetrahydro-7,12-dimethylbenz[a]anthracene in female SENCAR mice.

We have determined the skin tumor-initiating activity in SENCAR mice of two A-ring derivatives of 7,12-dimethylbenz[a]anthracene (DMBA). 4-Fluoro-7,12-dimethylbenz[a]anthracene at a dose of 200 nmol per mouse exhibited weak activity, producing 0.6 papillopmas per mouse; doses of 10 and 20 nmol per mouse had no activity. A derivative of DMBA with the A-ring reduced, 1,2,3,4-tetrahydro-7,12-dimethylbenz[a]anthracene (1,2,3,4,-H-DMBA), had substantial tumor-initiating activity when compared with the parent hydrocarbon. In one experiment, doses of 10 and 100 nmol per mouse gave rise to 1.6 and 9.5 papillomas per mouse, respectively; similar results were obtained in 3 additional experiments. Although the tumor-initiating activity of 1,2,3,4,-H4-DMBA was approximately one-tenth that of DMBA, this derivative was slightly (17%) more active than benzo[a]pyrene. 1,2,3,4-H4-DMBA was tested for the ability to induce mutations to 6-thioguanine-resistance in Chinese hamster V79 cells. In the absence of feeder cells capable of metabolizing polycyclic hydrocarbons, it was not mutagenic. However, in a cell-mediated mutation assay with secondary hamster embryo cells as activators, this derivative produced mutations in a dose-dependent manner and was approximately one-tenth as active as DMBA. These results indicate that metabolism of DMBA at positions 1-, 3-, 2- and 4- is important for biological activity and that for certain derivatives (i.e., 1,2,3,4-H4-DMBA), alternate pathways of metabolic activation may also be important.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1982

Effects of tumor-promoting phorbol diesters on neoplastic progression of Syrian hamster embryo cells.

The progression of normal Syrian hamster embryo cells to a neoplastic phenotype after treatment with a chemical carcinogen and continuous exposure to phorbol ester tumor promoters was studied in cell culture. Tumor promoters were able to rescue cell lines derived from individual carcinogen-treated colonies from a program of cellular senescence. In general, these cell lines did not grow in soft-agar medium or produce tumors in newborn hamsters at early passages but acquired these properties at later passages. These cell lines were used to study the temporal acquisition of a phenotypic characteristic of neoplastic rather than normal hamster embryo cells: the synergistic induction of the enzyme ornithine decarboxylase (ODC) by tumor promoter and serum growth factors (O'Brien, T. G., Saladik, D., and Diamond, L. Regulation of polyamine biosynthesis in normal and transformed hamster cells in culture. Biochim. Biophys. Acta, 632: 270, 1980). All cell lines that acquired neoplastic status with passage in culture exhibited the synergistic induction of ODC prior to their acquisition of the ability to either grow in soft-agar medium or produce tumors in newborn hamsters. Cell lines that responded to promoters with the synergistic induction of ODC accumulated greater levels of polyamines, especially putrescine, after promoter treatment than did normal cells. Tumor promoters did not affect the percentage of cells labeled with [3H]thymidine in preneoplastic cell lines, a finding similar to previous results in normal and neoplastic hamster cells. These studies demonstrate that tumor promoters can affect the early stages of neoplastic progression in carcinogen-treated Syrian hamster embryo cells and that a particular phenotypic property found in neoplastic hamster cells, the synergistic induction of ODC by tumor promoters and serum growth factors, is acquired by cell lines before they acquire neoplastic potential.

Animals↗
PubMed1981

Induction of cellular deoxyribonucleic acid synthesis in butyrate-treated cells by simian virus 40 deoxyribonucleic acid.

Sodium butyrate (3 mM) inhibited the entry into the S phase of quiescent 3T3 cells stimulated by serum, but had no effect on the accumulation of cellular ribonucleic acid. Simian virus 40 infection or manual microinjection of cloned fragments from the simian virus 40 A gene caused quiescent 3T3 cells to enter the S phase even in the presence of butyrate. NGI cells, a line of 3T3 cells transformed by simian virus 40, grew vigorously in 3 mM butyrate. Homokaryons were formed between G1 and S-phase 3T3 cells, Butyrate inhibited the induction of deoxyribonucleic acid synthesis that usually occurs in B1 nuclei when G1 cells are fused with S-phase cells. However, when G1 3T3 cells were fused with exponentially growing NGI cells, the 3T3 nuclei were induced to enter deoxyribonucleic acid synthesis. In tsAF8 cells, a ribonucleic acid polymerase II mutant that stops in the G1 phase of the cell cycle, no temporal sequence was demonstrated between the butyrate block and the temperature-sensitive block. These results confirm previous reports that certain virally coded proteins can induce cell deoxyribonucleic acid synthesis in the absence of cellular functions that are required by serum-stimulated cells. Our interpretation of these data is that butyrate inhibited cell growth by inhibiting the expression of genes required for the G0 leads to G1 leads to S transition and that the product of the simian virus 40 A gene overrode this inhibition by providing all of the necessary functions for the entry into the S phase.

Animals↗
PubMed1981

A comparative study of two parasympatholytic bronchodilator agents: ipratropium bromide and diphemanil methylsulfate.

Ipratropium and diphemanil are synthetic quaternary ammonium compounds with antimuscarinic properties. By using in vitro measurements of tension changes in isolated guinea-pig trachealis muscle strips and in vivo measurements of lung mechanics changes in anesthetized, vagotomized cats, the two drugs were compared in terms of their relative bronchodilator potency, mode of action and apparent site of activity in the bronchial tree. Ipratropium and diphemanil were about equipotent in antagonizing airway smooth muscle contraction induced by the cholinergic agonists, methacholine (in vitro) and carbachol (in vivo). When noncholinergic stimulation was used to augment smooth muscle tone, i.e., hypertonic potassium in the isolated preparations and serotonin in the vagotomized animals, only diphemanil exhibited significant bronchodilator activity. Simultaneous measurements of pulmonary resistance and dynamic compliance were used to partition in vivo bronchodilator effects between large and small airways. The parasympatholytic bronchodilator effects of both drugs were distributed uniformly along the bronchial tree, whereas the direct spasmolytic action of diphemanil appeared to manifest itself preferentially on large airways.

Animals↗
PubMed1981

An evaluation of triprolidine and pseudoephedrine in the treatment of allergic rhinitis.

A double-blind, parallel, placebo-controlled study was performed to assess the efficacy of a combination drug product containing the antihistamine, triprolidine, and the sympathomimetic, pseudoephedrine, in the treatment of allergic rhinitis. Allergic rhinitis was defined on the basis of coexistent nasal congestion and an aggregate symptom complex score which exceeded a pre-established value. Pseudoephedrine and triprolidine were shown to make distinct and separate contributions to the treatment of allergic rhinitis defined in this manner.

Airway Resistance↗
PubMed1980

Regulation of polyamine biosynthesis in normal and transformed hamster cells in culture.

Several aspects of polyamine biosynthesis were compared in low-passage hamster embryo fibroblasts and transformed hamster fibroblasts. Earlier studies had demonstrated a larger and longer-lasting induction of ornithine decarboxylase activity in transformed cells than in hamster embryo fibroblasts. The increases in intracellular polyamine concentrations after serum stimulation were much greater in chemically transformed HE68BP cells than in normal hamster fibroblasts. Treatment of confluent cultures with the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate, greatly potentiated ornithine decarboxylase induction by fresh medium in HE68BP cells, but not in hamster fibroblasts. A similar synergistic effect was observed when transformed cells, but not normal cells, were treated with the combination of insulin and promoter. HE68BP cells were capable of growth in medium containing serum concentrations as low as 0.5%, whereas only concentrations of 5% or more supported the growth of hamster embryo fibroblasts. Low serum concentrations induced ornithine decarboxylase in HE68BP cells but not in normal cells, and a given serum concentration always produced a greater induction of ornithine decarboxylase in transformed than in normal cells. Another enzyme involved in polyamine synthesis, S-adenosyl-L-methionine decarboxylase was induced in normal and transformed cells by serum-containing medium or tetradecanoylphorbol acetate, but in contrast to ornithine decarboxylase, no synergistic effect was seen in transformed cells exposed to the combination of fresh medium and the tumor promoter. A macromolecular inhibitor of ornithine decarboxylase was readily detected in hamster fibroblasts cultures treated with high concentrations of putrescine, but little or none of this inhibitor was found in HE68BP cultures. In both cell types, however, serum induction of ornithing decarboxylase was inhibited under conditions of excess putrescine. These results demonstrate several differences between normal and transformed hamster cells in the regulation of polyamine synthesis.

Animals↗