Mutagenicity of 1,3-butadiene at the Hprt locus of T-lymphocytes following inhalation exposures of female mice and rats.

The species specific response to 1,3-butadiene (BD), an important industrial chemical, was investigated by determining the influence of exposure duration and exposure concentration on the mutagenicity of BD in mice and rats and by defining the spectra of mutations in the Hprt gene T-cell mutants from control and BD-exposed mice. Female B6C3F1 mice and F344 rats (4-5 weeks old) were exposed by inhalation to 0, 20, 62.5, or 625 ppm of BD for up to 4 weeks (6 h/day, 5 days/week).

Molecular dosimetry of N-7 guanine adduct formation in mice and rats exposed to 1,3-butadiene.

1,3-Butadiene (BD) is a high-volume chemical used in the production of rubber and plastic. BD is a potent carcinogen in mice and a much weaker carcinogen in rats, and has been classified as a probable human carcinogen. Upon metabolic activation in vivo, it forms DNA-reactive metabolites, 1,2-epoxy-3-butene (EB), 1,2:3, 4-diepoxybutane (DEB), and 3,4-epoxy-1,2-butanediol (EBD).

Increased gene dosage augments antifreeze protein levels in transgenic Drosophila melanogaster.

One of the principal environmental adaptations of certain fishes inhabiting polar and northern coastal waters is the synthesis of antifreeze proteins (AFPs). AFPs bind to and prevent the growth of nascent ice crystals, thus depressing the serum freezing point. The transgenic expression of AFP holds great promise for conferring freeze resistance to commercially important plant and animal species.

Effect of coupling on volume-regulatory response of ciliary epithelial cells suggests mechanism for secretion.

The ciliary epithelium of the eye secretes the aqueous humor. It is a double epithelium arranged so that the apical surfaces of the nonpigmented ciliary epithelial (NPCE) and pigmented ciliary epithelial (PCE) cells face each other and the basolateral membranes face the inside of the eye and the blood, respectively. We have investigated the volume responses of both single cells and coupled pairs from this tissue to osmotic challenge.

Protection against atherosclerosis by estrogen is independent of plasma cholesterol levels in LDL receptor-deficient mice.

Low density lipoprotein (LDL) receptor-deficient (LDLR-/-) mice consuming a high fat diet were used to assess the effect of endogenous and exogenous estradiol (E2) on atherosclerosis. Sexually mature female mice were ovariectomized (OVX) and implanted with subcutaneous, slow-release pellets designed to release 6 microg/day of exogenous 17beta-estradiol (17beta-E2 ), 17alpha-estradiol (17alpha-E2 ), or placebo (E2- deficient). Sham-operated control female (endogenous E2 ) and male mice were studied as controls.

Quantitative determination of trimethylamine in urine by solid-phase microextraction and gas chromatography-mass spectrometry.

Trimethylaminuria (fish odour syndrome) is diagnosed from an increase in urinary excretion of trimethylamine with decreased trimethylamine oxide. We report a new quantitative stable isotope dilution gas chromatography-mass spectrometry procedure for the analysis of these metabolites using solid-phase microextraction (SPME). Both polydimethylsiloxane and mixed Carboxen-polydimethylsiloxane SPME fibres were found to be suitable for the headspace extraction of TMA.

Persistence of N7-(2,3,4-trihydroxybutyl)guanine adducts in the livers of mice and rats exposed to 1,3-butadiene.

Liquid chromatography (LC) in combination with tandem mass spectrometry (MS/MS) and stable isotope methodology was employed for the analysis of the N7-guanine (Gua) adducts derived from 1,2:3, 4-diepoxybutane (BDO2) a reactive metabolite of 1,3-butadiene (BD). Two diastereomeric forms of N7-(2,3,4-trihydroxybutyl)guanine (THBG) were identified in the livers of both mice and rats. One of the diastereomers [(+/-)-THBG] was formed by reaction of DNA with (+/-)-BDO2, and the other diastereomer (meso-THBG) was formed by reaction of DNA with meso-BDO2.

Disulfide bond mapping and structural characterization of spruce budworm antifreeze protein.

The 9-kDa, Thr-, Ser-, and Cys-rich thermal hysteresis protein from spruce budworm (sbwTHP) is 10-30 times more effective than fish antifreeze proteins (AFPs) at depressing solution freezing points via ice-crystal growth inhibition. Since this insect protein is only available in microgram quantities from its natural source, recombinant sbwTHP was produced from inclusion bodies in Escherichia coli by a refolding protocol. Incompletely folded forms were removed during ion-exchange and reverse-phase chromatography, resulting in fully active sbwTHP that was indistinguishable in its properties from native sbwTHP.

Culture and propagation of Hprt mutant T-lymphocytes isolated from mouse spleen.

The optimization of the mouse lymphocyte Hprt mutation assay has been impeded by the relatively poor growth potential of mouse T-cells in vitro, which leads to low cloning efficiencies (CEs) and limited expansion of Hprt mutant clones for molecular analysis of mutations occurring in control and treated mice. In this study, the addition and manipulation of concanavalin A (Con A), mouse interleukin-2 (IL-2), and a commercially available culture supplement, rat T-STIM with Con A, were used to identify growth conditions producing relatively high CEs for mouse T-cells. Supplementation of medium with 10% rat T-STIM, along with appropriate amounts of Con A for priming and exogenous IL-2 for cloning, resulted in average CEs of 15-16% in lymphocytes isolated from spleens of control mice (n = 32) or mice exposed to 1,3-butadiene (n = 27).

Cloning and characterization of an ecdysone receptor cDNA from Locusta migratoria.

To facilitate studies on the hormonal control of development in the migratory locust, Locusta migratoria, we have undertaken the cloning of cDNAs for nuclear hormone receptors. Sequences obtained by polymerase chain reaction (PCR) showed homology with receptor family members including the ecdysteroid receptor (EcR). A cDNA clone corresponding to the EcR fragment includes an open reading frame of 1622 nucleotides, predicting a 59 kDa protein showing clear homology with EcRs and distinct from other classes of nuclear receptors.

Antisense to MDR1 mRNA reduces P-glycoprotein expression, swelling-activated C1- current and volume regulation in bovine ciliary epithelial cells.

Native ciliary epithelial cells from the ciliary epithelium of the eye exhibit anti-P-glycoprotein (P-gp) immunofluorescence. We have used an antisense 'knock-down' approach to investigate the relationship between P-gp and the volume-activated chloride current (IC1,swell) and its role in volume regulation. An antisense oligonucleotide to the human multidrug resistance (MDR1) gene, taken up by the cells in a dose-dependent manner, reduced P-gp immunofluorescence, inhibited IC1,swell and significantly increased the latency of activation of IC1,swell.

One tone, two ears, three dimensions: a robotic investigation of pinnae movements used by rhinolophid and hipposiderid bats.

Bats, which echolocate using broadband calls, are believed to employ the passive acoustic filtering properties of the head and pinnae to provide spectral cues which encode 3-D target angle. Microchiropteran species whose calls consist of a single, constant frequency harmonic (i.e.

Comparison of the mutagenic potency of 1,3-butadiene at the hprt locus of T-lymphocytes following inhalation exposure of female B6C3F1 mice and F344 rats.

1,3-Butadiene (BD) is an indirect alkylating agent that has greater cancer potency in the mouse than in the rat. The purpose of the present study was to compare the mutagenic potency of BD at the hprt locus of T-lymphocytes of exposed mice and rats and to determine whether mutations induced in this marker gene can be used as a quantitative indicator for species differences in susceptibility to cancer. To this end, experiments were conducted to define the effects of exposure duration and the time elapsed after exposures on the frequency of hprt mutations (Mf) in T-cells from female B6C3F1 mice and F344 rats of similar age (4-5 weeks) when exposed to BD by inhalation.

Molecular analysis and prenatal diagnosis of human fumarase deficiency.

Fumarase deficiency is a rare autosomal recessive disorder of the citric acid cycle causing severe neurological impairment. The cDNA for both the rat and human enzymes has been cloned previously and shown to encode a coding region of 1.46 kb.

Quantitative analysis of 1,3-butadiene-induced DNA adducts in vivo and in vitro using liquid chromatography electrospray ionization tandem mass spectrometry.

1,3-Butadiene (BD) is a high volume industrial chemical which is known as a multi-site rodent carcinogen and is classified as a probable human carcinogen. Covalent interactions of the reactive epoxy metabolites of BD with DNA lead to the formation of DNA adducts which may cause mutations and tumor formation. In the present work, liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was employed for analyses of BD-induced DNA adducts in vitro and in vivo.

Induction of novel Grp75 isoforms by 2-deoxyglucose in human and murine fibroblasts.

Grp75 is a stress-inducible mitochondrial chaperone which has a high homology to senescence-related protein, p66mot mortalin. In human cells the mortalin gene assigns to the locus of a putative tumor suppressor gene for myeloid malignancies. In order to study expression and localization of Grp75 and p66mot in human and murine fibroblast lines, polyclonal antibodies were raised to conserved portions of each sequence.

Cultural sensitivity and readability of breast and prostate printed cancer education materials targeting African Americans.

Cancer prevention materials such as pamphlets, booklets, and fact sheets play a significant role in reducing cancer disparities. Little is documented in the literature about the cultural sensitivity of materials targeting African Americans. The Cancer Prevention Materials and African Americans project was conducted to assess the cultural sensitivity and readability of printed cancer education materials targeting African Americans.

Highly sensitive apurinic/apyrimidinic site assay can detect spontaneous and chemically induced depurination under physiological conditions.

One of the most prevalent lesions in DNA is the apurinic/apyrimidinic (AP) site, which is derived from the cleavage of the N-glycosyl bond by DNA glycosylase or by spontaneous depurination. AP sites are repaired by AP endonucleases during the process of base excision repair; however, an imbalance in this DNA repair system may cause mutations as well as cell death. We have established a sensitive and convenient slot-blot method to detect AP sites in genomic DNA using a novel aldehyde reactive probe (ARP), which reacts with the aldehydic group of ring-opened AP sites.

The regiospecific N-derivatization of histidine side chains: reinvestigation of a supposed N tau to N pi migration.

A report claiming that AcHisOMe reacts regiospecifically with 4-fluoronitrobenzene to give AcHis[tau Ph(NO2)]OMe, which on treatment with H2/Pd(C) undergoes a partial tau-pi shift to give some AcHis[pi Ph(NH2)]OMe, cannot be substantiated. 4(5)-Methylimidazole, a model for AcHisOMe, gives on reaction with 4-fluoronitrobenzene a 4:1 mixture of the regioisomers 1-(4-nitrophenyl),4-methylimidazole, corresponding to tau-substitution, and 1-(4-nitrophenyl),5-methylimidazole, corresponding to pi-substitution, each of which has been isolated and fully characterized, including proof of orientation. In both cases, treatment with H2/Pd(C) gives a single product, without any change of orientation in either case.

The antifreeze potential of the spruce budworm thermal hysteresis protein.

Antifreeze proteins (AFP) inhibit ice growth by surface adsorption that results in a depression of the freezing point below the melting point. The maximum level of this thermal hysteresis shown by the four structurally unrelated fish AFP is approximately 1.5 degrees C.

Intraperitoneal administration of coumarin causes tissue-selective depletion of cytochromes P450 and cytotoxicity in the olfactory mucosa.

Coumarin is a naturally occurring fragrant compound widely used in consumer products and also as a therapeutic agent. The effects of intraperitoneal (ip) and oral administration of coumarin on cytochrome P450 (P450) expression in olfactory mucosa were examined. A single ip injection of coumarin at 50 mg/kg resulted in a significant reduction of levels of CYP2A and CYP2G in the olfactory mucosa of Wistar rats and C57BL/6 mice at 48 hr following injection.

In vivo mutagenicity of ethylene oxide at the hprt locus in T-lymphocytes of B6C3F1 lacI transgenic mice following inhalation exposure.

Ethylene oxide (EO) is a direct-acting alkylating agent with the potential to induce cytogenetic alterations, mutations, and cancer. In the present study, the in vivo mutagenicity of EO at the hypoxanthine guanine phosphoribosyltransferase (hprt) locus of T-lymphocytes was evaluated following inhalation exposure of male B6C3F1 lacI transgenic mice. For this purpose, groups of male Big Blue mice at 6-8 (n = 4/group) and 8-10 (n = 5/group) weeks of age were exposed to 0, 50, 100, or 200 ppm EO for 4 weeks (6 h/day, 5 days/week).

Towards a reconciliation of the introns early or late views: triosephosphate isomerase genes from insects.

The gene encoding the glycolytic enzyme, triosephosphate isomerase (TPI; EC 5.3.1.

Neonatal encephalopathy with a pungent body odour.

A neonate had transient unexplained bleeding into the gut, severe encephalopathy, and an abnormal pungent body odour. An inherited metabolic defect was excluded. The malodour was due to methanethiol and hydrogen sulphide, identified in urine.