[A study of the mechanism of L-NNA on sleep inhibition]

In the present study, the sleep-waking cycle and the immunoreactivity of 5-HT-containing neurons in rats receiving intraperitoneal injections of N-Nitro-L-arginine (L-NNA, 50 mg/kg) and L-arginine (L-arg, 110 mg/kg) were observed respectively. The results showed that injection of L-NNA suppressed both slow wave sleep (SWS) and rapid eye movement sleep (REMS) and increased mean arterial pressure (MAP). L-arg markedly attenuated MAP, whereas SWS and REMS were unchanged. The effects of L-NNA on sleep and MAP were reversed by preinjection of L-arg. In comparison with control group, the positive cells in dorsal raphe nucleus (DR) and raphe magus nucleus (MnR) increased 2 h after injection of L-NNA. The effect was attenuated by preadministration of L-arg. All these results suggest that L-arg: NO pathway is involved in the regulation of sleep-waking cycle and the increment of the positive immunoreactivity of the 5-HT-containing neurons in the DR may be related to the sleep-suppressive effects induced by L-NNA.

Metal fume fever: characterization of clinical and plasma IL-6 responses in controlled human exposures to zinc oxide fume at and below the threshold limit value

Results from animal and preliminary human exposure studies have called into question whether the 5 mg/m3 8-hour time-weighted average threshold limit value (TLV) for zinc oxide fume is sufficient to protect workers against metal fume fever. The objectives of this study were to determine the clinical effects of exposures to low concentrations of zinc oxide and to ascertain whether these exposures elevated circulating levels of specific cytokines, which could account for the symptoms of the metal fume fever syndrome. Thirteen resting naive subjects inhaled, on separate days, air and 2.5 and 5 mg/m3 of furnace-generated zinc oxide fume for 2 hours. Subjects recorded symptoms and temperature and had blood drawn before and after each exposure. The mean (+/- SE) maximum rise in oral temperature at 6 to 12 hours after exposure was 1.4 +/- 0.3 degrees F after 5 mg/m3, compared with 0.6 +/- 0.5 degrees F after air exposure (P < 0.05). Mean temperature was also elevated after exposure to 2.5 mg/m3 zinc oxide (1.2 +/- 0.3 degrees F). In a parallel fashion, plasma levels of interleukin 6 (IL-6), a pyrogen, were significantly elevated after exposure to 5 mg/m3 zinc oxide. Mean IL-6 values (pg/mL) at pre-exposure and at 3 and 6 hours post-exposure were 1.9 (+/- 0.6), 2.8 (+/- 0.7), and 2.9 (+/- 0.6), respectively, on the air day and 1.6 (+/- 0.6), 4.4 (+/- 1.2), and 6.4 (+/- 1.1) on the 5 mg/m3 zinc oxide day. Zinc oxide exposure did not significantly affect plasma levels of tumor necrosis factor. Total symptom scores peaked 9 hours after the 5 mg/m3 zinc oxide exposure. Myalgias, cough, and fatigue were the predominant symptoms reported. Inhalation of zinc oxide for 2 hours at the current TLV of 5 mg/m3 produces fever and symptoms along with elevation in plasma IL-6 levels.

Extracellular proteins of Cryptococcus neoformans and host antibody response

Proteins secreted by the fungal pathogen Cryptococcus neoformans may be involved in invasion and could be useful in vaccine design. Despite the medical importance of this fungus, little is known about its extracellular proteins or the immune response to these antigens. To study C. neoformans extracellular proteins, 12 strains were metabolically radiolabeled and protein supernatants were analyzed. Both strain- and growth condition-dependent differences were observed. Enzymatic assays of filtered culture supernatants revealed butyrate esterase and caprylate esterase lipase activity for 11 of 12 strains, as well as acid phosphatase, naphthol-AS-BI-phosphohydrolase, and beta-glucosidase activities in some strains. Serum from infected rodents immunoprecipitated several secreted proteins, consistent with in vivo expression and development of an antibody response. For strain 24067, two immunodominant species, of approximately 75 and 30 kDa, were recognized. The relative intensity of the autoradiographic bands depended on the route of infection for both rats and mice. In summary, our results indicate that (i) there are multiple proteins in C. neoformans culture supernatants, (ii) there are strain differences in supernatant protein profiles, (iii) there are differences in supernatant protein profile depending on the growth conditions, (iv) there are several new extracellular and/or cell-associated enzymatic activities, and (v) antibodies to several supernatant proteins are made in the course of infection.

Mutations of the PATCHED gene in several types of sporadic extracutaneous tumors

Patients with basal cell nevus syndrome have a high incidence of multiple basal cell carcinomas, medulloblastomas, and meningiomas. Because somatic PATCHED (PTCH) mutations have been found in sporadic basal cell carcinomas, we have screened for PTCH mutations in several types of sporadic extracutaneous tumors. We found that 2 of 14 sporadic medulloblastomas bear somatic nonsense mutations in one copy of the gene and also deletion of the other copy. In addition, we identified missense mutations in PTCH in two of seven breast carcinomas, one of nine meningiomas, and one colon cancer cell line. No PTCH gene mutations were detected in 10 primary colon carcinomas and eighteen bladder carcinomas.

Influence of acid aerosol droplet size on structural changes in the rat lung caused by acute exposure to sulfuric acid and ozone

To investigate whether aerosol droplet size influences structural changes in the lung produced by short-term, concomitant exposure to ozone and sulfuric acid, groups of 10 rats were exposed 4 hr/day for 2 days to filtered air, 0.6 ppm ozone, 0.5 mg/m3 fine (aerosol mass median diameter (MMD) = 0.3 microm) or ultrafine (MMD = 0.06 microm) sulfuric acid, or a mixture of ozone and 0.5 mg/m3 fine or ultrafine sulfuric acid. The volume percentage of total parenchyma containing markedly to severely injured alveolar septae was measured morphometrically. There were no differences between the ultrafine or fine acid exposure groups and the sham group for any of the morphologic endpoints. Volume percentage of markedly to severely injured tissue was increased in the ultrafine, but not fine, mixture animals when compared with the ozone-only group. In addition, a synergistic interaction between ozone and ultrafine, but not fine, sulfuric acid was found for this endpoint. The bromodeoxyuridine cell labeling index in the periacinar region was greater in the rats exposed to the fine sulfuric acid and ozone mixture than that in rats exposed to ozone alone, and a synergistic interaction between ozone and fine sulfuric acid was found for this end point. None of the exposures produced any changes in ventilatory parameters. Thus, acid aerosol droplet size was found to influence the effect of sulfuric acid in modifying ozone-induced structural changes in the rat lung.

Ozone inactivates cyclooxygenase in human tracheal epithelial cells without altering PGHS-2 mRNA or protein

Exposure of human tracheal epithelial (TE) cells to ozone (0.1-0.5 ppm) leads to a transient increase followed by decreased production of prostaglandin (PG) E2 concomitant with dose-dependent loss and delayed recovery of cyclooxygenase (CO) activity [S.E. Alpert and R.W. Walenga. Am. J. Physiol. 269 (Lung Cell. Mol. Physiol. 13): L734-L743, 1995]. Formation of reactive oxygen species (ROS) in cultured tracheobronchial epithelial cells during ozone exposure was recently demonstrated (L.C. Chen and Q.Qu. Toxicol. Appl. Pharmacol. 143: 96-101, 1997). In the present study, we investigated if ROS generated by ozone-exposed human TE cells contribute to PGE2 production and/or CO inactivation and whether the delay in recovery of CO activity after ozone reflects impaired gene transcription and/or protein synthesis. Rapid, dose-dependent ROS generation, assessed by fluorescence of dihydrorhodamine 123, was detected in human TE monolayers exposed to 0.21-0.63 ppm ozone. In a different system, TE cells were exposed to air or 0.5 ppm ozone for 1 h by serial renewal/collection of an adherent film of media. Ozone-induced ROS formation, the transient increase and decline in PGE2, and CO inactivation were attenuated by an intracellular hydroxyl radical scavenger, 1,3-dimethyl-2-thiourea. Ibuprofen, a reversible CO inhibitor, prevented PGE2 release during ozone exposure (and hence autocatalytic CO inactivation) but not loss of CO activity. Although CO activity remained depressed for hours after ozone exposure, compared with air-exposed cultures, no differences were detected in mRNA and protein levels of prostaglandin endoperoxide G/H synthase 2 (PGHS-2), the only CO isoform present in human TE cells, or in the rate of de novo PGHS-2 synthesis. Our findings suggest that ozone-induced PGE2 production and CO inactivation are primarily the result of formation of intracellular oxidant molecules and that delayed recovery of CO activity in human TE cells after short-term ozone exposure is due to persistent inactivation of PGHS-2, rather than to interference with its synthesis.

Formation of intracellular free radicals in guinea pig airway epithelium during in vitro exposure to ozone

In vivo exposure to ozone (O3) has been shown to cause airway epithelial damage and lipid peroxidation. The oxidation of polyunsaturated fatty acids has been shown to produce hydrogen peroxide and aldehydes with reactive oxygen species (ROS) as intermediates. These products of ozonation may react with other bioorganic molecules and cause cellular damage. To assess the production of ROS, confluent primary cultures of guinea pig airway epithelial cells were grown on Costar membrane with a liquid-air interface and exposed to 0.2, 0.4, and 0.6 ppm O3. The concentrations of intracellular ROS during the exposure were monitored using the fluorescent dye dihydrorhodamine-123. The intracellular concentration of ROS increased immediately upon the commencement of the O3 exposure and persisted until the end of the exposure period (up to 1 hr). The concentration of ROS increased with increasing O3 concentration. To determine the species of ROS produced during O3 exposure, airway epithelial cells were perfused with dimethyl sulfoxide (DMSO), sodium formate (hydroxyl radical scavengers), NaN3 (catalase inhibitor), or diethyl-dithio carbamate (DEDC, superoxide dismutase inhibitor) prior to and during the exposure period and the fluorescent intensity was monitored continuously. While both DMSO and sodium formate decreased the concentration of ROS, DEDC and NaN3 had no effect. We concluded that hydroxyl radicals instead of H2O2 or superoxide anions were produced immediately following the commencement of O3 exposure in guinea pig airway epithelial cells in an exposure concentration-dependent fashion.

Ozone-induced IL-8 expression and transcription factor binding in respiratory epithelial cells

Ozone, one of the most reactive oxidant gases to which humans are routinely exposed, induces inflammation in the lower airways. The airway epithelium is one of the first targets that inhaled ozone will encounter, but its role in airway inflammation is not well understood. Expression of inducible genes involved in the inflammatory response, such as interleukin (IL)-8, is controlled by transcription factors. Expression of the IL-8 gene is regulated by the transcription factors nuclear factor (NF)-kappaB, NF-IL-6, and possibly activator protein-1 (AP-1). Type II-like epithelial cells (A549) were grown on a collagen-coated membrane and exposed in vitro to 0.1 ppm ozone or air. Exposure to ozone induced DNA-binding activity of NF-kappaB, NF-IL-6, and AP-1. IL-8 mRNA and IL-8 protein levels were also increased after ozone exposure. These results link ozone-induced DNA-binding activity of transcription factors and the production of IL-8 by epithelial cells thus demonstrating a potential cellular cascade resulting in the recruitment of inflammatory cells into the airway lumen.

c-erbB-2/p185-directed therapy in human lung adenocarcinoma

BACKGROUND

These experiments were conducted to determine whether p185 can be therapeutically targeted in adenocarcinoma of the lung using an anti-p185-gelonin conjugate. c-erbB-2/p185 is overexpressed in up to one third of non-small cell lung cancers. CALU-3 is a human lung adenocarcinoma cell line that overexpresses p185. muMoAb-4D5 is a murine anti-p185 monoclonal immunoglobulin G1. Gelonin is a potent type 1 ribosomal inhibitory protein.

METHODS

4D5 and gelonin were covalently modified and linked. Purification was confirmed by SDS-polyacrylamide gel electrophoresis. Dose-dependent cytotoxicity was quantified using 3H-thymidine uptake by CALU-3 cells after incubation with 4D5-gelonin conjugate or with control substances (4D5, gelonin, unconjugated 4D5 + gelonin, or control antibody MOPC-21).

RESULTS

The 4D5-gelonin conjugate showed a 50% inhibitory concentration of 3.5 x 10(-10) mol/L, but 4D5 alone demonstrated no cytotoxic effect. Gelonin and the unconjugated 4D5-gelonin mixture had one tenth the cytotoxicity of the 4D5-gelonin conjugate (inhibitory concentration = 6.5 x 10(-9) mol/L and 8.5 x 10(-9) mol/L, respectively). The conjugate exhibited minimal toxicity against a p185-negative cell line (NIH3T3).

CONCLUSIONS

Selective and efficient killing of human lung adenocarcinoma cells can be achieved in vitro using c-erbB-2/p185-directed therapy.

Altered regulation of inducible nitric oxide synthase expression in macrophages from senescent mice

We investigated the capacity of mouse macrophages obtained from senescent animals to respond in vitro to microbial stimuli. Significant hypersecretion of nitric oxide (NO) was observed in thioglycolate-elicited macrophages from senescent mice compared with those obtained from young mice in response to lipopolysaccharide (LPS). In contrast, both cell populations manifested equivalent responses to LPS with respect to tumor necrosis factor alpha secretion. Further, macrophages from senescent animals also showed potentiated responses to both zymosan and heat-killed Staphylococcus aureus, as assessed by NO production. Both cell populations were equivalently inhibited by a competitive inhibitor of NO synthase NG-monomethyl-L-arginine. Since endogenous beta interferon (IFN-beta) is recognized as an essential cofactor for LPS-induced NO production by macrophages, we investigated the role of IFN-beta in enhancing the capacity of both macrophage populations for LPS-induced NO production. Macrophages from young mice were minimally activated by LPS alone to express inducible NO synthase (iNOS), and the response was significantly potentiated by the addition of IFN-beta. These findings were confirmed by immunocytochemical staining of iNOS in which the frequency of iNOS-positive cells in response to LPS was enhanced in the presence of IFN-beta. Reverse transcription-PCR analyses revealed that macrophages from senescent animals produced larger amounts of iNOS mRNA in response to LPS. Further, exogenous IFN-beta potentiated iNOS mRNA expression in macrophages from young mice. In contrast, the frequency of LPS-activated macrophages for iNOS expression was markedly increased during senescence and addition of IFN-beta did not significantly change this frequency. These results correlated with reverse transcription PCR data showing high levels of iNOS mRNA in LPS-stimulated macrophages from senescent mice. LPS-induced NO production in macrophages from both young and senescent mice was inhibited by neutralizing antibody to either IFN-beta or IFN-gamma. Mixed cultures of macrophages from young and senescent mice stimulated with LPS manifested significantly enhanced NO production relative to that which would be predicted from an additive response of the two macrophage populations stimulated separately. The differential responsiveness of NO production observed with thioglycolate-elicited macrophages from young and senescent mice was also observed in resident macrophages but, interestingly, not in bone marrow culture-derived macrophages. These results suggest that environmental factors may be responsible for the potentiated NO responses of macrophages from senescent mice. Collectively, these data suggest that macrophages from senescent animals manifest an altered mechanism for regulation of macrophage function in NO production and iNOS expression by constitutive and/or induced expression of autoregulatory cytokines.

The tar fraction of cigarette smoke does not promote arteriosclerotic plaque development

In addition to being the single greatest known environmental cause of cancer, cigarette smoke (CS) is also a major contributor to heart disease. We reported previously that 1) inhalation of either mainstream or sidestream CS promotes aortic arteriosclerotic plaque development; 2) 1,3 butadiene, a vapor-phase component of CS, promotes plaque development at 20 ppm, which at the time was only 2 times higher than the threshold limit value; and 3) individual tar fraction carcinogens in CS, including polynuclear aromatic hydrocarbons (PAHs) and nitrosamines, either do not promote plaque development or do so only at high concentrations. These results suggested that the tar fraction is not the primary source of plaque-promoting agents in CS. We asked whether repeated exposure to the tar fraction of CS, collected in a cold trap (TAR), promotes plaque development in an avian model of arteriosclerosis. Acetone extracts of mainstream CS tar from burning, unfiltered reference cigarettes were solubilized in dimethyl sulfoxide (DMSO) and injected weekly into cockerels for 16 weeks (25 mg/kg/week). Positive controls were injected weekly with the synthetic PAH carcinogen, 7,12 dimethylbenz(a)anthracene (DMBA) dissolved in DMSO and negative controls were injected with DMSO. Plaque location and prevalence did not differ from group to group. Morphometric analysis of plaque cross-sectional areas showed that plaque sizes, which are log-normally distributed, were significantly larger in the DMBA cockerels compared to both the TAR and DMSO groups. There were no significant differences in plaque size between DMSO and TAR cockerels. The results reported here, combined with other recent findings, support the conclusion that the primary arteriosclerotic plaque-promoting components of CS are in the vapor phase.

Amplifications of oncogene erbB-2 and chromosome 20q in breast cancer determined by differentially competitive polymerase chain reaction

A new method of measuring gene copy number in small samples of DNA was used to measure amplification of the erbB-2 gene and of chromosome 20q in breast cancer. This method, termed 'differentially competitive polymerase chain reaction' (DC-PCR) combines the advantages of two other techniques for measuring amplification by PCR, namely differential PCR and competitive PCR. The DC-PCR methodology was evaluated for sensitivity and specificity by comparing amplification of erbB-2 measured by DC-PCR with that obtained by fluorescence in situ hybridization (FISH) for 42 cases or Southern blotting and/or slot blot analysis for 34 cases. There was over 90 percent concordance with both FISH and Southern blotting and/or slot blot analysis. DC-PCR was used to further characterize the newly described amplicon at chromosome 20q. By analyzing DNA from 10 breast cancer cell lines at 7 different loci, we identified a potential common region of amplification of approximately 5 centimorgans at chromosome 20q13 bordered by loci D20S52 and RMC20C100-S1. One hundred and seventeen cases of primary breast cancer were evaluated for amplification at these two loci. Amplification at one or more loci, defined as > 1.5 fold higher copy number than that of normal DNA, was found in 25 cases (21%). Sixteen cases were amplified at only one of the two probes (12 cases for RMC20C001-S1 and 4 cases for D20S52), suggesting that the target gene lies between the two markers or that there are two independent target genes within a small chromosome region.

Generation of stable test atmospheres of cocaine base and its pyrolyzate, methylecgonidine, and demonstration of their biological activity

Generating controlled test atmospheres of known chemical identity and airborne concentration upon demand is a significant technical obstacle that limits the scope and repeatability of studies of inhaled substances. We addressed this problem as applied to the generation of atmospheres that result from heating crack cocaine, which include both cocaine and its pyrolyzate methylecgonidine (MEG). A condensation aerosol generator was used to generate atmospheres comprised of monodisperse particles of cocaine, MEG, or mixtures of both that are of submicron size suitable for deposition in the alveolar region of primates. Compressed air seeded with nanometer-size sodium chloride particles was passed through a constant depth of molten cocaine or MEG in a bead bed, reheated, and condensed to an aerosol within an annulus of cold air. To achieve control of a mixture of both compounds, MEG was condensed onto cocaine particles in a separate coating step. On-line analytical instruments provided verification of airborne concentration, estimates of particle size, and dispersion as well as chemical identity. Specific airway conductance (SGaw), heart rate, and rectal and skin temperatures were measured in squirrel monkeys breathing atmospheres containing condensation aerosols of cocaine or MEG free base. SGaw was reduced after inhalation of either base, and both induced temperature and cardiovascular changes, demonstrating that the aerosols so generated had biological activity.

Extracellular proteinase activity of Cryptococcus neoformans

Extracellular proteinase activity was studied for eight strains of Cryptococcus neoformans var. neoformans and two strains of Cryptococcus neoformans var. gattii. Proteinase activity was measured by protein agar clearance, azoalbumin hydrolysis, gelatin liquefaction, and protein substrate polyacrylamide gel electrophoresis. All strains of C. neoformans produced extracellular proteolytic activity. Maximal extracellular proteinase activity in supernatants of C. neoformans cultures was associated with late logarithmic- and stationary-phase cultures. C. neoformans was able to utilize murine immunoglobulin G1, bovine immunoglobulin G, and human complement factor 5 for growth in media containing these proteins as the sole sources of carbon and nitrogen, suggesting a capacity to degrade immunologically important proteins. Protein substrate polyacrylamide gel electrophoresis revealed several bands with proteolytic activity at apparent molecular masses of 200, 100, and 50 kDa. The results confirm the existence of extracellular proteinase activity for C. neoformans.

Activation of a human peroxisome proliferator-activated receptor by the antitumor agent phenylacetate and its analogs

The aromatic fatty acid phenylacetate and its analogs induce tumor cytostasis and differentiation in experimental models. Although the underlying mechanisms of action are not clear, effects on lipid metabolism are evident. We have now examined whether these compounds, structurally similar to the peroxisome proliferator clofibrate, affect the human peroxisome proliferator-activated receptor (hPPAR), a homolog of the rodent PPAR alpha, a transcriptional factor regulating lipid metabolism and cell growth. Gene transfer experiments showed activation of hPPAR, evident by the increased expression of the reporter gene chloramphenicol acetyltransferase linked to PPAR-response element from either the rat acyl-CoA oxidase or rabbit CYP4A6 genes. The relative potency of tested drugs in the co-transfection assay was: 4-iodophenylbutyrate > 4-chlorophenylbutyrate > clofibrate > phenylbutyrate > naphthylacetate > 2,4-D > 4-chlorophenylacetate > phenylacetate >> indoleacetate. Phenylacetylglutamine, in which the carboxylic acid is blocked, was inactive. The ability of the aromatic fatty acids to activate PPAR was confirmed in vivo, as CYP4A mRNA levels increased in hepatocytes of treated rats. Further studies using human prostate carcinoma, melanoma, and glioblastoma cell lines showed a tight correlation between drug-induced cytostasis, increased expression of the endogenous hPPAR, and receptor activation documented in the gene-transfer model. These results identify phenylacetate and its analogs as a new class of aromatic fatty acids capable of activating hPPAR, and suggest that this nuclear receptor may mediate tumor cytostasis induced by these drugs.

Reliability of the Neonatal Neurobehavioral Examination--Chinese version

A Chinese version of the Neonatal Neurobehavioral Examination (NNE-C) was applied to 15 high-risk infants and five normal term infants for investigation of reliability. The infants were assessed by three physical therapists to examine inter-rater reliability and reassessed by one of the therapists within 2 days to examine test-retest reproducibility. The internal consistency of the NNE-C scale was high, with an alpha coefficient of 0.84. The inter-rater reliability was high for item scores (kappa coefficients > 0.75 for 81% of the items) and for section and total scores (all intraclass correlation coefficients > 0.80). The test-retest reproducibility was moderate for item scores (kappa coefficients > 0.40 for 85% of the items) and was high for section and total scores (all intraclass correlation coefficients > 0.80). We conclude that the NNE-C scale is clinically feasible and reliable for the evaluation of neurobehavioral functions of high-risk and normal term infants in Chinese-speaking societies.

Vasomolol: an ultra short-acting and vasorelaxant vanilloid type beta 1-adrenoceptor antagonist

The ultra-short-acting and vasorelaxant beta 1-adrenoceptor blocking activities of vasomolol, a guaiacoxypropanolamine derivative of vanillic acid ethyl ester, were studied. Vasomolol (0.5, 1.0, 3.0 mg/kg intravenously, i.v.) produced a dose-dependent bradycardia response and demonstrated particularly a hypotensive action with an ultra-short-acting property in pentobarbital-anesthetized normotensive rats. Vasomolol's steady state of beta-blockade was attained < or = 10 min after initial infusion, and a rapid recovery from blockade occurred after discontinuation of the infusion, although intravenous infusion of vasomolol (300 micrograms/kg/min) could not inhibit pressor responses induced by (-)phenylephrine (10 micrograms/kg i.v.). In isolated rat thoracic aorta, vasomolol (1-10 microM) inhibited vascular smooth muscle contractions induced by both (-)phenylephrine (10(-5) M) and high K+ (75 mM) concentration dependently. This inhibitory effect of vasomolol was more sensitive on K(+)-induced than on (-)phenylephrine-induced contractions, suggesting that the block of Ca2+ influx may involve the major mechanism of vasorelaxation. In isolated guinea pig tissues, vasomolol (0.01-10 microM) antagonized the (-)isoproterenol (ISO)-induced positive inotropic and chronotropic effects of the atria and tracheal relaxation responses in a concentration-dependent manner. The parallel shift to the right of the concentration-response curve of (-)ISO suggested that vasomolol was a beta-adrenoceptor competitive antagonist. The effect of vasomolol was more potent on atria than on tracheal tissues, indicating that it possesses beta 1-adrenoceptor selectivity. In addition, vasomolol did not show intrinsic sympathomimetic activity (ISA). Moreover, the binding characteristics of vasomolol were evaluated in [3H]dihydroalprenolol ([3H]DHA) binding to porcine ventricular membranes. Vasomolol was an ultra-short-acting and highly selective beta 1-adrenoceptor antagonist with vasorelaxant activity and is devoid of ISA.

Novel actions of aspirin and sodium salicylate: discordant effects on nitric oxide synthesis and induction of nitric oxide synthase mRNA in a murine macrophage cell line

Aspirin and sodium salicylate each inhibit to a similar extent the production of nitric oxide (NO) in the RAW 264.7 murine macrophage cell line following stimulation by either lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma). The similar potencies of aspirin and sodium salicylate indicate that acetylation of cellular macromolecules is not essential for the observed effects. The failure of added prostaglandin E2 to overcome the effects of aspirin or sodium salicylate indicates that these effects are not simply the result of inhibition of prostaglandin synthesis. The inhibition of NO production occurs irrespective of the effect of these agents on induction of nitric oxide synthase (iNOS) mRNA by LPS or IFN-gamma. Aspirin and sodium salicylate inhibit iNOS mRNA induction in LPS-stimulated cells but enhance iNOS mRNA induction in IFN-gamma-stimulated cells. In contrast, these agents consistently inhibit induction of argininosuccinate synthetase mRNA in both LPS- and IFN-gamma-stimulated cells. Concentrations of aspirin in the 3-10 mM range inhibit induced NO production and expression of iNOS protein without inhibiting induction of iNOS mRNA. Discordances between effects on NO synthesis and induction of iNOS mRNA indicate that aspirin and sodium salicylate have multiple sites of action in their effects on pathways that are involved in the production of NO by stimulated RAW 264.7 cells.

Ozone-induced alteration in beta-adrenergic pharmacological modulation of pulmonary macrophages

Ozone is a ubiquitous air pollutant which can affect numerous function s of the respiratory system. However, previous work has not provided any information concerning its ability to modulate pharmacological receptors of pulmonary macrophages. This study examined, using a chemiluminescence assay, the beta-adrenergic modulation of pulmonary macrophages harvested from rabbits exposed for 3 hr/day for 5 days to 0.1, 0.3 or 0.6 ppm ozone (O3) or to 3 hr/day for 20 days to 0.1 or 0.3 ppm. Receptor activity was monitored using release of reactive oxygen species (ROS) following administration to the cells of the beta2-receptor agonist, isoproterenol. An O3-exposure concentration-dependent response was observed for isoproterenol efficacy following 5-day exposures, in that 0.1 ppm O3 induced a significant enhancement of beta-adrenergic inhibition of ROS production, 0.3 ppm ozone produced no significant change from control, and 0.6 ppm decreased inhibition. No significant effects on beta-adrenergic modulation were noted following the 20-day exposures. The results of this study suggest that short-term repeated exposures to O3 are capable of inducing alterations in the pharmacological functioning of pulmonary macrophages, while longer term exposures may result in adaptation. Alterations in receptor function have implications in terms of pulmonary defense and disease.

Dietary retinoic acid inhibits mouse skin carcinogenesis irrespective of age at initiation

In the two-stage protocol of skin carcinogenesis, the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) is applied to the skin of mice at around seven weeks of age. We previously performed DMBA initiation at three weeks of age to study the effect of pharmacological (30 micrograms/g diet) dietary retinoic acid (RA) on skin carcinogenesis. In this study we asked whether dietary pharmacological RA is equally effective against skin carcinogenesis when mice are initiated with (DMBA) at 7 weeks of age and then subjected to weekly applications of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) or mezerein (MEZ) for 20 weeks. Similar to the three-week initiation protocol, high dietary RA inhibited papilloma incidence and yield in MEZ- but not in TPA-promoted female SENCAR mice. In addition, carcinoma incidence and yield were decreased by high dietary RA in TPA- as well as MEZ-treated mice. These data demonstrate that the high dietary RA diet is as effective in inhibiting papilloma and carcinoma formation when the DMBA is applied at seven weeks of age as at three weeks.

Genetic relatedness of Cryptococcus neoformans clinical isolates grouped with the repetitive DNA probe CNRE-1

Cryptococcus neoformans isolates from eight patients with cryptococcal infection were previously assigned into three groups on the basis of repetitive DNA probe (CNRE-1) restriction fragment length polymorphisms. These groups accounted for a disproportionate number of recent clinical isolates in New York City. To further examine the genetic relatedness of isolates within and across CNRE-1 groups, the DNA sequence of the 779-base URA5 gene from each strain was amplified and sequenced. The number of nucleotide differences occurred in the third codon position or in introns. Pairwise comparisons revealed average nucleotide differences within a CNRE-1 group of 4.8 +/- 2.6 (n = 8) and between CNRE-1 groups of 21.9 +/- 7.0 (n =20) (P <0.001) Analysis of URA5 sequences defined three groups that were congruent with those defined by CNRE-1 restriction fragment length polymorphisms. PCR amplification of an rDNA intergenic spacer revealed conservation of the intergenic spacer length within groups. Electrophoretic karyotyping did not distinguish between two isolates in each of two CNRE-1 groups. DNA from all isolates studied hybridized to an alpha mating type-specific probe. We interpret these results as suggesting a clonal population structure for some pathogenic isolates of C. neoformans in New York City.

Purification of chlorpromazine-sensitive GTPase from rat cerebral cortex

The chlorpromazine-sensitive GTPase from the cell membrane of rat cerebral cortex was purified to homogenity by using DEAE Bio-Gel A agarose, hydroxyapatite and heparin agarose chromatography. The purified chlorpromazine-sensitive GTPase was purified 370-fold to obtain a final specific activity of 40 mumol GTP hydrolyzed2min/mg protein. The purified enzyme was inhibited by chlorpromazine but not by compound 48/80. Magnesium was required for its activity instead of calcium. The purified enzyme had an apparent pH optimum of 8.0, and molecular weight was estimated to be 58,000.

Increased susceptibility of ras-transformed cells to phenylacetate is associated with inhibition of p21ras isoprenylation and phenotypic reversion

Alterations in the expression of ras oncogenes are characteristic of a wide variety of human neoplasms. Accumulating evidence has linked elevated ras expression with disease progression and with failure of tumors to respond to conventional therapies, including radiotherapy and certain chemotherapies. These observations led us to investigate the response of ras-transformed cells to the differentiation-inducer phenylacetate (PA). Using gene transfer models, we show that PA caused cytostasis in ras-transformed mesenchymal cells, associated with increased expression of 2',5'-oligoadenylate synthetase, an enzyme implicated in negative growth control. PA also induced phenotypic reversion characterized by loss of anchorage-independent growth, reduced invasiveness and increased expression of collagen alpha type I, a marker of cell differentiation. The anti-tumor activity of PA was observed in cases involving either Ha- or Ki-ras and was independent of the mode of oncogene activation. Interestingly, in contrast to their relative resistance to radiation and doxorubicin, ras-transformed cells were significantly more sensitive to PA than their parental cells. The profound changes in tumor cell and molecular biology were associated with reduced isoprenylation of the ras-encoded p21. Our results indicate that PA can suppress the growth of ras-transformed cells, resistant otherwise to free-radical based therapies, through interference with p21ras isoprenylation, critical to signal transduction and maintenance of the malignant phenotype.