Abstract  In this study, we introduce the double-barrel carbon probe (DBCP)-a simple, affordable microring electrode-which enables the collection and analysis of single cells independent of cellular positioning. The target cells were punctured by utilizing an electric pulse between the two electrodes in DBCP, and the cellular lysates were collected by manual aspiration using the DBCP. The mRNA in the collected lysate was evaluated quantitatively using real-time PCR. The histograms of single-cell relative gene expression normalized to GAPDH were fit to a theoretical lognormal distribution. In the tissue culture model, we focused on angiogenesis to prove that multiple gene expression analysis was available. Finally, we applied DBCP for the embryonic stem (ES) cell-derived cardiomyocytes to substantiate the capability of the probe to collect cells, even from high-volume samples such as spheroids. This method achieves high sensitivity for mRNA at the single-cell level and is applicable in the analysis of various biological samples independent of cellular positioning.

Abstract  36 reviews covering 64 substances are presented in this volume. In each review the data is presented under the following headings: introduction, animal data, mutagenic and genotoxic information, human data, scientific conclusions, need for further work, references.

Abstract  Groups of 50 B6C3F1 mice of each sex were exposed to air containing of 1,2-dibromo-3-chloropropane at concentrations of 0.6 or 3.0 ppm for 6 hours per day, 5 days per week for 103 weeks. Untreated controls consisted of 50 mice of each sex. All surviving animals were killed at 104 weeks. Adenomas, squamous cell papillomas, adenocarcinomas, squamous cell carcinomas, carcinosarcomas, fibrosarcomas, and hemangiosarcomas of the nasal cavity occurred in male and female mice with dose related trends. Eighty-seven percent of the high dose female mice had nearly twice as many tumors as the high dose males (47%). Fourtynine percent of malignant neoplasms of the high dose female mice infiltrated the brain or metastasized to the lungs. Whereas two animals (4%) of the low dose female mice showed infiltrating carcinomas, no male mice exhibited this feature.

Abstract  The plant-parasitic nematodes Criconemoides lobatum, Hoplolaimus tylenchiformis, and Tylenchorhynchus dubius were present in the top 7.5 cm of sod consisting of numerous stolons and fibrous roots. Phenamiphos and 1,2-dibromo-3-chloropropane (DBCP) controlled all three species, whereas ethoprop and oxamyl controlled H. tylenchiformis and T. dubius but not C. lobatum. Benomyl and carbofuran controlled H. tylenchiformis but had poor control of C. lobatum and T. dubius. The effectiveness of carbofuran varied with the type of formulation, being most effective as a quick-release formulation. C. lobatum was the most difficult to control with chemicals. No chemical treatment improved the growth of 'Astoria colonial' bentgrass (A. tenuis Sibth.) or Kentucky bluegrass (Poa pratensis L.) under the moist condtions prevalent in these tests.

Abstract  Relative to nematicides with greater fuming capabilities, 1,2-dibromo-3-chloropropane (DBCP) moved nonuniformly through soil. DBCP concentrations in soil were reduced by low soil temperature and the presence of lime or roots within the soil profile, Applications by either water or chisel injection provided DBCP movement to 120 cm and below. Concentrations were least persistent in the upper 15 cm of the field surface and in one situation where application was not followed by irrigation. Values for Henry's Constant are reported for DBCP at a range of solution temperatures. Certain advantages and disadvantages of soil atmosphere sampling of DBCP are discussed.

Abstract  The population density of Meloidogyne incognita was significantly reduced in land that was fallowed or cropped to crotalaria, marigold, bermudagrass, or bahiagrass. The rate of population decline caused by different cropping systems was influenced by initial population densities. Crotalaria, marigold, and bare fallow were about equally effective in reducing the density of M. incognita below dctectable lcvels, usually requiring 1-3 yr. Bahiagrass and bcrmudagrass required 4-5 yr or longer to reduce M. incognita below a detectable level. A high population density of Trichodorus christiei developed in land cropped 5 yr to bermudagrass, bahiagrass, okra, and marigold. Population densities of Pratylenchus brachyurus and Xiphinema americanum increased in land cropped to crotalaria or bermudagrass. Belonolabnus Iongicaudatus was detected only in land cropped to bermudagrass, The effectiveness of nematicides in reducing M. incognita infection was rclatcd to nematode population density resulting from 5 yr of different cropping systems. Treatment with aldicarb reduced M. incognita below detectable levels following all cropping systems; treatment with ethoprop following all cropping systems except okra, treatment wflh ethylene dibromide following bahiagrass or fallow; and treatment with DBCP only after 5 yr of fallow. Tomato transplant growth was affected .by both cropping systems and nematicide treatment. Transplants grown after crotalaria and bahiagrass were significantly larger than those grown after other crops. Also, treatment with aldicarb and ethoprop significantly increased transplant size.

Abstract  Pressurized injection of nematicidal solutions was effective for control of nematodes within trees and vines. Significant (P = 0.01) control of Pratylenchus vulnus on grape was attained with four nonfumigants (carbofuran, oxamyl, phenamiphos, and sulfocarb) and one fumigant nematicide (DBCP). Pratylenchus penetrans was controlled (P = 0.05 and 0.1) in apples and walnuts with sulfocarh and oxamyl. This species also was controlled in apples with carbofuran and phenamiphos. The advantages of pressure injection over traditional methods of nematicide applications are discussed.

Abstract  A bioassay for possible carcinogenicity of technical-grade dibromochloropropane (DBCP) was conducted using Osborne-Mendel rats and B6C3F1 mice. DBCP in corn oil was administered by gavage 5 days a week, at either of two dosages, to groups of 50 male and 50 female animals of each species. Initial dosage levels for the chronic bioassay were selected on the basis of a preliminary subchronic toxicity test. Subsequent dosage adjustments were made during the course of the chronic bioassay. The time-weighted average dosages of DBCP in the chronic study were 29 mg/kg/day for the high dose rats of both sexes, and 15 mg/kg/day for the low dose rats of both sexes. The time-weighted average concentrations for the high dose male and female mice were 219 and 209 mg/kg/day, respectively. The time-weighted average concentrations for the low dose male and female mice were 114 and 110 mg/kg day, respectively. For each species, 20 animals of each sex were placed on test as vehicle controls. These animals were intubated with corn oil at the same time that dosed animals were intubated with DBCP mixtures. Twenty animals of each sex were placed on test as untreated controls for each species. These animals received no gavage treatments. DBCP was administered to the high dose male and high dose female rats for 64 weeks prior to sacrifice, and to the low dose female rats for 73 weeks prior to sacrifice. The low dose male rats were treated for 78 weeks followed by an additional 5 weeks of observation. The high dose male and female mice were treated for 47 weeks prior to sacrifice; the low dose male mice were treated for 59 or 60 weeks prior to sacrifice, and the low dose female mice were treated for 60 weeks prior to sacrifice. In rats and mice of both sexes, statistically significant incidences of squamous-cell carcinomas of the forestomach occurred in each dosed group and a significant positive association existed between dosage level and tumor incidence. The incidences of adenocarcinomas of the mammary gland were statistically significant in female rats when the treated groups were compared to the controls. Toxic nephropathy was also observed at elevated incidences in all of the treated rats and mice when compared to their respective untreated or vehicle control groups. Under the conditions of this study, DBCP is a stomach carcinogen in rats and mice of both sexes and is carcinogenic to the mammary gland in female rats.

Abstract  Gas-liquid chromatography was used to detect movement of the nematicide, 1,2-dibromo-3-chloropropane (DBCP), in soil columns containing top- and subsoil of Astatula fine sand. Topsoil contained 1.4-1.6% organic matter and subsoil 0.20-0.25%. DBCP was applied at various rates as aqueous drenches. Depth of penetration was controlled by organic matter in topsoil and varied with the amount of water applied. Maximum DBCP penetration after 14 days was 28 cm; maximum water infiltration, 115 cm. Maximum depth of penetration was obtained with a water emulsion of 30 mug/ml of DBCP applied in 15 cm of water. DBCP applied in 5 cm of water to soils containing 2.0% and 0.125% organic matter penetrated 6 cm and 60 cm, respectively.

Abstract  Yields of four soybean, Glycine max, cultivars were increased with subsoiling under the row and application of the nematicide, DBCP i 1,2-dibromo-3-chloropropane) in Tiflon sandy loam heavily infested with the root-knot nematode Meloidogyne incognita. These cultivars represent four maturity groups: very early (V), "Essex', early (VI), "Davis': medium (VII), 'Ransom'; and late (VIII), ' Hutton '. The average increase for the four cullivars was about the same for subsoiling or DBCP. When the treatmcnts were used together, the increase was greater than when either was used alone, but the effects were not additive. Increased yields were obtained with subsoiling and DBCP for the most nematode resistant cultivar, Hutton, as well as for the most susccptiblc, Davis. Subsoiling reduced root-knot galling in nonfumigated plots but did not affect it in fumigated plots. On 12 September, M. incognita larvae were most numerous at the 0- to 20 cm depth, intermediate at 20 to 33 cm depth and least numerous at 33 to 46 cm depth, Subsoiling did not affect larval populations at the three levels.

Abstract  Considering the operational differences between the process tubular electrode and GMAW process, two welding processes competitive in terms of quality and productivity, was evaluated a methodology to the productive capacity of each process under different aspects. It was realized a comparative study of melting rate, deposition rate and efficiency deposition, concluding with an analysis of the productive capacity of each wire in question. Welds beads were evaluated using the wire E71T-1 and ER 7056, under shielding gas 100% CO2 and Ar +25% CO2 at different current levels, using groove plates. For enable a good comparison with the practical reality of each consumable, were tried to work with every combination wire/shielding gas and appropriate conditions of contact-tip-to-work-piece distance and arc voltage (for the current range studied, solid wire was used in short-circuit, using a smaller DBCP). The volume of the weld beads per meter was made the same for each level of current.). In general, the tubular wire used showed a higher deposition rate than solid wire, but with a higher consumption of material to form the same weld bead. An economic analysis showed that with the tubular wire is possible to perform a bead in less time (higher productivity), and the higher cost may be the result of the price of products on time.

Abstract  3-Chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone (MX) formed during chlorination of water containing natural organic substances, is a very potent bacterial mutagen. Recently, tumours at multiple sites were reported in rats given MX-containing drinking water. We have investigated the genotoxicity of MX in mammalian cells exposed in vitro and in vivo using alkaline filter elution to detect DNA single-strand breaks and/or alkali-labile sites (SSBs). Concentrations as high as 100 and 300 mu M MX were required to induce detectable levels of SSBs in the HL-60 cells. If MX treatment was carried out in the presence of DNA repair inhibitors (AraC plus hydroxyurea), the sensitivity of the assay to detect MX-induced SSBs was increased by a factor of 100. The presence of serum proteins during exposure resulted in a minor reduction of the MX-induced DNA damage in HL-60 cells at the lowest MX concentrations. In primary cultures of testicular cells as well as in resting human peripheral blood mononuclear cells (PBMC), a slightly increased level of SSBs was observed at MX-concentrations above 30 mu M, this effect was not further increased by repair inhibitors. In LLC-PK1 renal proximal tubular epithelial cells and in growth stimulated human peripheral PBMC, increased SSBs were detected at MX concentrations as low as low as 3-10 mu M and higher using repair inhibitors, and at 10 times higher concentrations without repair inhibitors. No dose dependent DNA damage was detected in the liver, kidney, spleen and colon of male B6C3F1 mice administrated high doses of MX (40 and 80 mg kg(-1)). Moderately increased and dose dependent SSBs were detected in the liver and kidney in the presence of DNA repair inhibitors during MX treatment, but no such increase was observed in the spleen and colon. (C) 1999 Elsevier Science B.V. All rights reserved.

Abstract  Because of the high rates of sperm production and large extragonadal sperm reserves of sexually rested male rats, mating trials are insensitive for detecting test-induced alterations in sperm production rates. Mating trials might be more sensitive if, independently of any experimental treatments under study, the number of sperm per mating was closer to the minimum requirements for normal fertility. The present study was undertaken to assess the impact of unilateral vasectomy and/or matings with up to three females in succession, for 1 hour each, on the number of sperm per mating and fertility, in comparison to corresponding values for males allowed unlimited matings with a receptive female overnight. Unilateral vasectomy did not affect sperm production, extragonadal sperm reserves, or removal of contralateral sperm during ejaculation (P > 0.05) but caused a 50% decrease in sperm numbers per mating. Sperm output, judged from numbers of residual extragonadal sperm in unmated and mated males, was excessive (290 x 10[6]) during conventional overnight mating with intact males and during the first and second hours of restricted mating (105 and 184 x 10(6) respectively, for intact males; one-half of these amounts for unilaterally vasectomized males). In contrast, sperm output during the third successive mating was minimal (nonmeasurable) but adequate, since pregnancy rates were similar for females mated first, second, or third in succession (P > 0.05). Since successive matings reduce the number of sperm per mating by natural methods, this approach may enhance the sensitivity of mating tests when applied for assessing the potential effects of experimental treatments on sperm production.