Neisseria gonorrhoeae drives Chlamydia trachomatis into a persistence-like state during in vitro co-infection

Chlamydia trachomatis and Neisseria gonorrhoeae are the most prevalent bacterial sexually transmitted infections (STIs) globally. Despite frequent co-infections in patients, few studies have investigated how mono-infections may differ from co-infections. We hypothesized that a symbiotic relationship between the pathogens could account for the high rates of clinical co-infection. During in vitro co-infection, we observed an unexpected phenotype where the C. trachomatis developmental cycle was impaired by N. gonorrhoeae. C. trachomatis is an obligate intracellular pathogen with a unique biphasic developmental cycle progressing from infectious elementary bodies (EB) to replicative reticulate bodies (RB), and back. After 12 hours of co-infection, we observed fewer EBs than in a mono-infection. Chlamydial genome copy number remained equivalent between mono- and co-infections. This is a hallmark of Chlamydial persistence. Chlamydial persistence alters inclusion morphology but varies depending on the stimulus/stress. We observed larger, but fewer, Chlamydia during co-infection. Tryptophan depletion can induce Chlamydial persistence, but tryptophan supplementation did not reverse the co-infection phenotype. Only viable and actively growing N. gonorrhoeae produced the inhibition phenotype in C. trachomatis. Piliated N. gonorrhoeae had the strongest effect on C. trachomatis, but hyperpiliated or non-piliated N. gonorrhoeae still produced the phenotype. EB development was modestly impaired when N. gonorrhoeae were grown in transwells above the infected monolayer. C. trachomatis serovar L2 was not impaired during co-infection. Chlamydial impairment could be due to cytoskeletal or osmotic stress caused by an as-yet-undefined mechanism. We conclude that N. gonorrhoeae induces a persistence-like state in C. trachomatis that is serovar dependent.

Toward Elucidating the Human Gut Microbiota-Brain Axis: Molecules, Biochemistry, and Implications for Health and Diseases

In recent years, a substantial amount of data have supported an active role of gut microbiota in mediating mammalian brain function and health. Mining gut microbiota and their metabolites for neuroprotection is enticing but requires that the fundamental biochemical details underlying such microbiota-brain crosstalk be deciphered. While a neuronal gut-brain axis (through the vagus nerve) is not disputable, accumulating studies also point to a humoral route (via blood/lymphatic circulation) by which innumerable microbial molecular cues translocate from local gut epithelia to circulation with potentials to further cross the blood-brain barrier and reach the brain. In this Perspective, we review a realm of gut microbial molecules to evaluate their fate, function, and neuroactivities in vivo as mediated by microbiota. We turn to seminal studies of neurophysiology and neurologic disease models for the elucidation of biochemical pathways that link microbiota to gut-brain signaling. In addition, we discuss opportunities and challenges for advancing the microbiota-brain axis field while calling for high-throughput discovery of microbial molecules and studies for resolving the interspecies, interorgan, and interclass interaction among these neuroactive microbial molecules.

Assessing Option B+ retention and infant follow-up in Lilongwe, Malawi

Malawi launched Option B+, a program for all pregnant or breastfeeding HIV-positive women to begin lifelong combination antiretroviral therapy (cART), in July 2011. This study characterises a portion of the continuum of care within an antenatal setting in Lilongwe. Women testing HIV-positive and having a cART initiation record at Bwaila Antenatal Clinic from July 2013 to January 2014 were included. Using logistic regression models, we analysed relationships between maternal characteristics and return for infant testing. Among 490 HIV-positive women with a cART initiation record, 360 (73%) were retained at three months. Of these, 203 (56%) were adherent. Records of infant testing were located for 204 women (42%). Women who were not retained were less likely to have an early infant diagnosis record (aOR = 0.20; 95% CI: 0.10, 0.41). Among the women retained, there was a non-significant association between maternal adherence and infant testing (OR = 1.35; 95% CI: 0.89, 2.06). Women lost at earlier continuum stages, who are at higher risk for mother-to-child-transmission, were less likely to bring infants for testing. Even with a test-and-treat program, many women did not remain in care or bring their infant for testing. Facilitating strategies to improve these measures remains an important unmet need.

DNA Product Formation in Female Sprague-Dawley Rats Following Polyhalogenated Aromatic Hydrocarbon (PHAH) Exposure

DNA oxidation damage has been regarded as one of the possible mechanisms for the hepatic carcinogenesis of dioxin-like compounds (DLCs). In this study, we evaluated the toxic equivalency factor (TEF) from the standpoint of induced DNA oxidation products and their relationship to toxicity and carcinogenicity. Nine DNA oxidation products were analyzed in the liver of female Sprague–Dawley rats exposed to 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD) alone or the tertiary mixture of TCDD, 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126), and 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) by gavage for 14, 31, and 53 weeks (5 days/week) by LC–MS/MS: 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dGuo); 1,N⁶-etheno-2′-deoxyadenosine (1,N⁶-εdAdo); N²,3-ethenoguanine (N²,3-εG); 7-(2-oxoethly)guanine (7-OEG); 1,N²-etheno-2′-deoxyguanosine (1,N²-εdGuo); malondialdehyde (M₁dGuo); acrolein (AcrdGuo); crotonaldehyde (CrdGuo); and 4-hydroxynonenal (HNEdGuo) derived 2′-deoxyguanosine adducts. Exposure to TCDD (100 ng/kg/day) significantly induced 1,N⁶-εdAdo at 31 and 53 weeks, while no increase of 8-oxo-dGuo was observed. Significant increases were observed for 8-oxo-dGuo and 1,N⁶-εdAdo at all time points following exposure to the tertiary mixture (TEQ 100 ng/kg/day). Exposure to TCDD for 53 weeks only significantly increased 1,N⁶-εdAdo, while increases of N²,3-εG and 7-OEG were only found in the highest dose group (100 ng/kg/day). Exposure to the tertiary mixture for 53 weeks had no effect on N²,3-εG in any exposure group (TEQ 0, 22, 46, or 100 ng/kg/day), while significant increases were observed for 1,N⁶-εdAdo (all dose groups), 8-oxo-dGuo (46 and 100 ng/kg/day), and 7-OEG (100 ng/kg/day). While no significant increase was observed at 53 weeks for 1,N²-εdGuo, M₁dGuo, AcrdGuo, or CrdGuo following exposure to TCDD (100 ng/kg/day), all of them were significantly induced in animals exposed to the tertiary mixture (TEQ 100 ng/kg/day). This oxidation DNA product data suggest that the simple TEF methodology cannot be applied to evaluate the diverse patterns of toxic effects induced by DLCs.

[Paediatric palliative care: multidisciplinary and pro-active]

Every child with a life-limiting or threatening illness, and his or her family, has a right to palliative care. Palliative care is not limited to end-of-life care, but starts from the moment of diagnosis and is independent of whether there are curative options. To optimise quality of life of both the child and the family, the emphasis of care should be on both somatic and psychosocial and spiritual aspects from the very start, and goals should be set together with the child and the family. A multidisciplinary and pro-active approach is essential if this is to be achieved. It is, therefore, strongly recommended that at least every academic hospital should have a multidisciplinary paediatric palliative care team.

Differentiation of Moraxella Bovoculi sp. nov. from other Coccoid Moraxellae by the Use of Polymerase Chain Reaction and Restriction Endonuclease Analysis of Amplified DNA

Moraxella oris was historically the only coccoid Moraxella identified in cultures of ocular fluid from cattle with infectious bovine keratoconjunctivitis (IBK) and could be morphologically and biochemically differentiated from Moraxella bovis. Moraxella bovoculi sp. nov. is a recently characterized Moraxella isolated from ulcerated eyes of calves with IBK in northern California in 2002. Like Moraxella ovis, M. bovoculi sp. nov. is a gram-negative coccus/diplococcus. All 18 original isolates of M. bovoculi sp. nov. possessed phenylalanine deaminase (PADase) activity and could therefore be differentiated from M. ovis and M. bovis. During the characterization of 44 additional isolates of hemolytic gram-negative cocci that were cultured from ulcerated eyes of IBK-affected calves, 2 PADase-negative isolates were identified that could not be differentiated biochemically from M. ovis; however, the DNA sequence of the 16S-23S intergenic spacer region (ISR) of the isolates matched the 16S-23S ISR DNA sequence of M. bovoculi sp. nov. To facilitate the identification of PADase-negative moraxellae, a polymerase chain reaction (PCR) coupled with restriction enzyme digestion analysis of amplified DNA was developed. Amplification of the 16S-23S ISR followed by AfaI digestion of amplified DNA could differentiate M. bovoculi sp. nov. from M. ovis and other moraxellae. The DNA sequence analysis of the amplified 16S-23S ISR from the 42 PADase-positive isolates of hemolytic gram-negative cocci indicated that all were M. bovoculi sp. nov. and all possessed an AfaI site. A PCR coupled with restriction analysis of amplified DNA can aid in identifying M. bovoculi sp. nov.

Polychlorinated Biphenyls Induce Oxidative DNA Adducts in Female Sprague-Dawley Rats

Polychlorinated biphenyls (PCBs) are organic chemicals that were traditionally produced and widely used in industry as mixtures and are presently formed as byproducts of pigment and dye manufacturing. They are known to persist and bioaccumulate in the environment. Some have been shown to induce liver cancer in rodents. Although the mechanism of the toxicity of PCBs is unknown, it has been shown that they increase oxidative stress, including lipid peroxidation. We hypothesized that oxidative stress-induced DNA damage could be a contributor for PCB carcinogenesis and analyzed several DNA adducts in female Sprague-Dawley rats exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB 126), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), and a binary mixture (PCB 126 + 153) for 14, 31, and 53 wks. Eight adducts were measured to profile oxidative DNA lesions, including 8-oxo-deoxyguanosine (8-oxo-dG), 1,N(6)-ethenodeoxyadenosine (1,N(6)-εdA), N(2),3-ethenoguanine (N(2),3-εG), 1,N(2)-ethenodeoxyguanosine (1,N(2)-εdG), as well as malondialdehyde (M1dG), acrolein (AcrdG), crotonaldehyde (CrdG), and 4-hydroxynonenal-derived dG adducts (HNEdG) by LC-MS/MS analysis. Statistically significant increases were observed for 8-oxo-dG and 1,N(6)-εdA concentrations in hepatic DNA of female rats exposed to the binary mixture (1000 ng/kg/day + 1000 μg/kg/day) but not in rats exposed to PCB 126 (1000 ng/kg/day) or PCB 153 (1000 μg/kg/day) for 14 and 31 wks. However, exposure to PCB 126 (1000 ng/kg/day) for 53 wks significantly increased 8-oxo-dG, 1,N(6)-εdA, AcrdG, and M1dG. Exposure to PCB 153 (1000 μg/kg/day) for 53 wks increased 8-oxo-dG, and 1,N(6)-εdA. Exposure to the binary mixture for 53 wks increased 8-oxo-dG, 1,N(6)-εdA, AcrdG, 1,N(2)-εdG, and N(2),3-εG significantly above control groups. Increased hepatic oxidative DNA adducts following exposure to PCB 126, PCB 153, or the binary mixture shows that an increase in DNA damage may play an important role in hepatic toxicity and carcinogenesis in female Sprague-Dawley rats.

Neisserial Opa Protein-CEACAM Interactions: Competition for Receptors as a Means of Bacterial Invasion and Pathogenesis

Carcino-embryonic antigen-like cellular adhesion molecules (CEACAMs), members of the immunoglobulin superfamily, are responsible for cell-cell interactions and cellular signaling events. Extracellular interactions with CEACAMs have the potential to induce phagocytosis, as is the case with pathogenic Neisseria bacteria. Pathogenic Neisseria species express opacity-associated (Opa) proteins, which interact with a subset of CEACAMs on human cells, and initiate the engulfment of the bacterium. We demonstrate that recombinant Opa proteins reconstituted into liposomes retain the ability to recognize and interact with CEACAMs in vitro but do not maintain receptor specificity compared to that of Opa proteins natively expressed by Neisseria gonorrhoeae. We report that two Opa proteins interact with CEACAMs with nanomolar affinity, and we hypothesize that this high affinity is necessary to compete with the native CEACAM homo- and heterotypic interactions in the host. Understanding the mechanisms of Opa protein-receptor recognition and engulfment enhances our understanding of Neisserial pathogenesis. Additionally, these mechanisms provide insight into how human cells that are typically nonphagocytic can utilize CEACAM receptors to internalize exogenous matter, with implications for the targeted delivery of therapeutics and development of imaging agents.

Despite differential gene expression profiles pediatric MDS derived mesenchymal stromal cells display functionality in vitro

Pediatric myelodysplastic syndrome (MDS) is a heterogeneous disease covering a spectrum ranging from aplasia (RCC) to myeloproliferation (RAEB(t)). In adult-type MDS there is increasing evidence for abnormal function of the bone-marrow microenvironment. Here, we extensively studied the mesenchymal stromal cells (MSCs) derived from children with MDS. MSCs were expanded from the bone-marrow of 17 MDS patients (RCC: n=10 and advanced MDS: n=7) and pediatric controls (n=10). No differences were observed with respect to phenotype, differentiation capacity, immunomodulatory capacity or hematopoietic support. mRNA expression analysis by Deep-SAGE revealed increased IL-6 expression in RCC- and RAEB(t)-MDS. RCC-MDS MSC expressed increased levels of DKK3, a protein associated with decreased apoptosis. RAEB(t)-MDS revealed increased CRLF1 and decreased DAPK1 expressions. This pattern has been associated with transformation in hematopoietic malignancies. Genes reported to be differentially expressed in adult MDS-MSC did not differ between MSC of pediatric MDS and controls. An altered mRNA expression profile, associated with cell survival and malignant transformation, of MSC derived from children with MDS strengthens the hypothesis that the micro-environment is of importance in this disease. Our data support the understanding that pediatric and adult MDS are two different diseases. Further evaluation of the pathways involved might reveal additional therapy targets.

Comparative analysis of the relationship between trichloroethylene metabolism and tissue-specific toxicity among inbred mouse strains: kidney effects

Trichloroethylene (TCE) is a well-known environmental and occupational toxicant that is classified as carcinogenic to humans based on the epidemiological evidence of an association with higher risk of renal-cell carcinoma. A number of scientific issues critical for assessing human health risks from TCE remain unresolved, such as the amount of kidney-toxic glutathione conjugation metabolites formed, interspecies and interindividual differences, and the mode of action for kidney carcinogenicity. It was postulated that TCE renal metabolite levels are associated with kidney-specific toxicity. Oral dosing with TCE was conducted in subacute (600 mg/kg/d; 5 d; 7 inbred mouse strains) and subchronic (100 or 400 mg/kg/d; 1, 2, or 4 wk; 2 inbred mouse strains) designs. The quantitative relationship was evaluated between strain-, dose, and time-dependent formation of TCE metabolites from cytochrome P-450-mediated oxidation (trichloroacetic acid [TCA], dichloroacetic acid [DCA], and trichloroethanol) and glutathione conjugation [S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2-dichlorovinyl)glutathione], and various kidney toxicity phenotypes. In subacute study, interstrain differences in renal TCE metabolite levels were observed. In addition, data showed that in several strains kidney-specific effects of TCE included induction of peroxisome proliferator-marker genes Cyp4a10 and Acox1, increased cell proliferation, and expression of KIM-1, a marker of tubular damage and regeneration. In subchronic study, peroxisome proliferator-marker gene induction and renal toxicity diminished while cell proliferative response was elevated in a dose-dependent manner in NZW/LacJ but not C57BL/6J mice. Overall, data demonstrated that renal TCE metabolite levels are associated with kidney-specific toxicity and that these effects are strain dependent.

Comparative analysis of the relationship between trichloroethylene metabolism and tissue-specific toxicity among inbred mouse strains: liver effects

Trichloroethylene (TCE) is a widely used organic solvent. Although TCE is classified as carcinogenic to humans, substantial gaps remain in our understanding of interindividual variability in TCE metabolism and toxicity, especially in the liver. A hypothesis was tested that amounts of oxidative metabolites of TCE in mouse liver are associated with hepatic-specific toxicity. Oral dosing with TCE was conducted in subacute (600 mg/kg/d; 5 d; 7 inbred mouse strains) and subchronic (100 or 400 mg/kg/d; 1, 2, or 4 wk; 2 inbred mouse strains) designs. The quantitative relationship was evaluated between strain-, dose-, and time-dependent formation of TCE metabolites from cytochrome P-450-mediated oxidation (trichloroacetic acid [TCA], dichloroacetic acid [DCA], and trichloroethanol) and glutathione conjugation [S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2-dichlorovinyl)glutathione] in serum and liver, and various hepatic toxicity phenotypes. In subacute study, interstrain variability in TCE metabolite amounts was observed in serum and liver. No marked induction of Cyp2e1 protein levels in liver was detected. Serum and hepatic levels of TCA and DCA were correlated with increased transcription of peroxisome proliferator-marker genes Cyp4a10 and Acox1 but not with degree of induction in hepatocellular proliferation. In subchronic study, serum and liver levels of oxidative metabolites gradually decreased over time despite continuous dosing. Hepatic protein levels of CYP2E1, ADH, and ALDH2 were unaffected by treatment with TCE. While the magnitude of induction of peroxisome proliferator-marker genes also declined, hepatocellular proliferation increased. This study offers a unique opportunity to provide a scientific data-driven rationale for some of the major assumptions in human health assessment of TCE.

Ethenoguanines undergo glycosylation by nucleoside 2'-deoxyribosyltransferases at non-natural sites

Deoxyribosyl transferases and functionally related purine nucleoside phosphorylases are used extensively for synthesis of non-natural deoxynucleosides as pharmaceuticals or standards for characterizing and quantitating DNA adducts. Hence exploring the conformational tolerance of the active sites of these enzymes is of considerable practical interest. We have determined the crystal structure at 2.1 Å resolution of Lactobacillus helveticus purine deoxyribosyl transferase (PDT) with the tricyclic purine 8,9-dihydro-9-oxoimidazo[2,1-b]purine (N2,3-ethenoguanine) at the active site. The active site electron density map was compatible with four orientations, two consistent with sites for deoxyribosylation and two appearing to be unproductive. In accord with the crystal structure, Lactobacillus helveticus PDT glycosylates the 8,9-dihydro-9-oxoimidazo[2,1-b]purine at N7 and N1, with a marked preference for N7. The activity of Lactobacillus helveticus PDT was compared with that of the nucleoside 2'-deoxyribosyltransferase enzymes (DRT Type II) from Lactobacillus leichmannii and Lactobacillus fermentum, which were somewhat more effective in the deoxyribosylation than Lactobacillus helveticus PDT, glycosylating the substrate with product profiles dependent on the pH of the incubation. The purine nucleoside phosphorylase of Escherichia coli, also commonly used in ribosylation of non-natural bases, was an order of magnitude less efficient than the transferase enzymes. Modeling based on published active-site structures as templates suggests that in all cases, an active site Phe is critical in orienting the molecular plane of the purine derivative. Adventitious hydrogen bonding with additional active site residues appears to result in presentation of multiple nucleophilic sites on the periphery of the acceptor base for ribosylation to give a distribution of nucleosides. Chemical glycosylation of O9-benzylated 8,9-dihydro-9-oxoimidazo[2,1-b]purine also resulted in N7 and N1 ribosylation. Absent from the enzymatic and chemical glycosylations is the natural pattern of N3 ribosylation, verified by comparison of spectroscopic and chromatographic properties with an authentic standard synthesized by an unambiguous route.

Opa+ Neisseria gonorrhoeae exhibits reduced survival in human neutrophils via Src family kinase-mediated bacterial trafficking into mature phagolysosomes

During gonorrhoeal infection, there is a heterogeneous population of Neisseria gonorrhoeae (Gc) varied in their expression of opacity-associated (Opa) proteins. While Opa proteins are important for bacterial attachment and invasion of epithelial cells, Opa+ Gc has a survival defect after exposure to neutrophils. Here, we use constitutively Opa- and OpaD+ Gc in strain background FA1090 to show that Opa+ Gc is more sensitive to killing inside adherent, chemokine-treated primary human neutrophils due to increased bacterial residence in mature, degradative phagolysosomes that contain primary and secondary granule antimicrobial contents. Although Opa+ Gc stimulates a potent oxidative burst, neutrophil killing of Opa+ Gc was instead attributable to non-oxidative components, particularly neutrophil proteases and the bactericidal/permeability-increasing protein. Blocking interaction of Opa+ Gc with carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) or inhibiting Src family kinase signalling, which is downstream of CEACAM activation, enhanced the survival of Opa+ Gc in neutrophils. Src family kinase signalling was required for fusion of Gc phagosomes with primary granules to generate mature phagolysosomes. Conversely, ectopic activation of Src family kinases or coinfection with Opa+ Gc resulted in decreased survival of Opa- Gc in neutrophils. From these results, we conclude that Opa protein expression is an important modulator of Gc survival characteristics in neutrophils by influencing phagosome dynamics and thus bacterial exposure to neutrophils' full antimicrobial arsenal.

Immediate and long-term somatic effects, and health-related quality of life of BM donation during early childhood. A single-center report in 210 pediatric donors

Since 1968, when Leiden undertook the first successful European pediatric BM transplantation with a 7-year-old sibling donor, more than 300 young children have donated BM in our unit. We first retrospectively studied a cohort of 210 donors, younger than 13 years at donation, to survey procedures of donor eligibility and study immediate effects of BM donation. We then performed a long-term follow-up (FU) and health-related quality of life (HRQoL) study. Despite documentation of previous medical conditions, no child was declared unfit to donate. We found that iron deficiency anemia or low-iron stores in BM did not result in treatment or extended FU. Harvest volumes exceeded 15 mL/kg in 65% of donors, with more than half requiring allogeneic blood transfusions. Donors had no structured FU after their first post-donation control. In this study, 25% of donors reported at least one somatic complaint at long-term FU. Finally long-term HRQoL revealed high scores in most subdomains (representing a higher QoL), compared to norm groups. These results indicate the need for development of (inter)national guidelines for pediatric stem cell donor care management.

Minimum inhibitory concentrations of selected antimicrobial agents for Moraxella bovoculi associated with infectious bovine keratoconjunctivitis

Infectious bovine keratoconjunctivitis (IBK) has been associated with ocular infections by Moraxella bovis, the established etiologic agent of IBK, and more recently, Moraxella bovoculi, a recently described species of Moraxella. To assist in designing rational treatment regimens for M. bovoculi infections associated with IBK, the in vitro susceptibilities of 57 M. bovoculi field isolates cultured from eyes of cattle with IBK in California from 2002 through 2007 were determined. The minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC(90)) of the following 18 antibiotics tested in the present study were: danofloxacin and enrofloxacin: ≤0.12 µg/ml; ampicillin and ceftiofur: ≤0.25 µg/ml; penicillin: 0.25 µg/ml; gentamicin: ≤1 µg/ml; chlortetracycline, oxytetracycline, and tiamulin: 1 µg/ml; florfenicol: 0.5 µg/ml; trimethoprim-sulfamethoxazole: ≤2/38 µg/ml; clindamycin: 2 µg/ml; neomycin and tilmicosin: ≤4 µg/ml; tulathromycin: 4 µg/ml; spectinomycin and tylosin: 16 µg/ml; and sulfadimethoxine: >256 µg/ml. The low MIC(90) of these M. bovoculi isolates suggests that commonly used antibiotics for treatment of IBK associated with M. bovis should also be effective against M. bovoculi.

Hemoglobin adducts in workers exposed to 1,6-hexamethylene diisocyanate

We investigated the utility of 1,6-hexamethylene diamine (HDA) hemoglobin adducts as biomarkers of exposure to 1,6-hexamethylene diisocyanate (HDI) monomer. Blood samples from 15 spray painters applying HDI-containing paint were analyzed for hemoglobin HDA (HDA-Hb) and N-acetyl-1,6-hexamethylene diamine (monoacetyl-HDA-Hb) by GC-MS. HDA-Hb was detected in the majority of workers (≤1.2-37 ng/g Hb), whereas monoacetyl-HDA-Hb was detected in one worker (0.06 ng/g Hb). The stronger, positive association between HDA-Hb and cumulative HDI exposure (r(2) = 0.3, p < 0.06) than same day exposure (p ≥ 0.13) indicates long-term elimination kinetics for HDA-Hb adducts. This association demonstrates the suitability of HDA-Hb adducts for further validation as a biomarker of HDI exposure.

Synthesis of uniformly 13C-labeled polycyclic aromatic hydrocarbons

Convergent synthetic pathways were devised for efficient synthesis of a series of uniformly (13)C labeled polycyclic aromatic hydrocarbons de novo from U-(13)C-benzene and other simple commercially-available (13)C-starting compounds. All target products were obtained in excellent yields, including the alternant PAH U-(13)C-naphthalene, U-(13)C-phenanthrene, U-(13)C-anthracene, U-(13)C-benz[a]anthracene, U-(13)C-pyrene and the nonalternant PAH U-(13)C-fluoranthene.

Occupational exposure to HDI: progress and challenges in biomarker analysis

1,6-Hexamethylene diisocyanate (HDI) is extensively used in the automotive repair industry and is a commonly reported cause of occupational asthma in industrialized populations. However, the exact pathological mechanism remains uncertain. Characterization and quantification of biomarkers resulting from HDI exposure can fill important knowledge gaps between exposure, susceptibility, and the rise of immunological reactions and sensitization leading to asthma. Here, we discuss existing challenges in HDI biomarker analysis including the quantification of N-acetyl-1,6-hexamethylene diamine (monoacetyl-HDA) and N,N'-diacetyl-1,6-hexamethylene diamine (diacetyl-HDA) in urine samples based on previously established methods for HDA analysis. In addition, we describe the optimization of reaction conditions for the synthesis of monoacetyl-HDA and diacetyl-HDA, and utilize these standards for the quantification of these metabolites in the urine of three occupationally exposed workers. Diacetyl-HDA was present in untreated urine at 0.015-0.060 μg/l. Using base hydrolysis, the concentration range of monoacetyl-HDA in urine was 0.19-2.2 μg/l, 60-fold higher than in the untreated samples on average. HDA was detected only in one sample after base hydrolysis (0.026 μg/l). In contrast, acid hydrolysis yielded HDA concentrations ranging from 0.36 to 10.1 μg/l in these three samples. These findings demonstrate HDI metabolism via N-acetylation metabolic pathway and protein adduct formation resulting from occupational exposure to HDI.

Urine 1,6-hexamethylene diamine (HDA) levels among workers exposed to 1,6-hexamethylene diisocyanate (HDI)

Urinary 1,6-hexamethylene diamine (HDA) may serve as a biomarker for systemic exposure to 1,6-hexamethylene diisocyanate (HDI) in occupationally exposed populations. However, the quantitative relationships between dermal and inhalation exposure to HDI and urine HDA levels have not been established. We measured acid-hydrolyzed urine HDA levels along with dermal and breathing-zone levels of HDI in 48 automotive spray painters. These measurements were conducted over the course of an entire workday for up to three separate workdays that were spaced approximately 1 month apart. One urine sample was collected before the start of work with HDI-containing paints and subsequent samples were collected during the workday. HDA levels varied throughout the day and ranged from nondetectable to 65.9 microg l(-1) with a geometric mean and geometric standard deviation of 0.10 microg l(-1) +/- 6.68. Dermal exposure and inhalation exposure levels, adjusted for the type of respirator worn, were both significant predictors of urine HDA levels in the linear mixed models. Creatinine was a significant covariate when used as an independent variable along with dermal and respirator-adjusted inhalation exposure. Consequently, exposure assessment models must account for the water content of a urine sample. These findings indicate that HDA exhibits a biphasic elimination pattern, with a half-life of 2.9 h for the fast elimination phase. Our results also indicate that urine HDA level is significantly associated with systemic HDI exposure through both the skin and the lungs. We conclude that urinary HDA may be used as a biomarker of exposure to HDI, but biological monitoring should be tailored to reliably capture the intermittent exposure pattern typical in this industry.

Structural characterization of formaldehyde-induced cross-links between amino acids and deoxynucleosides and their oligomers

Exposure to formaldehyde results in the formation of DNA-protein cross-links (DPCs) as a primary genotoxic effect. Although DPCs are biologically important and eight amino acids have been reported to form stable adducts with formaldehyde, the structures of these cross-links have not yet been elucidated. We have characterized formaldehyde-induced cross-links of Lys, Cys, His, and Trp with dG, dA, and dC. dT formed no cross-links, nor did Arg, Gln, Tyr, or Asn. Reaction of formaldehyde with Lys and dG gave the highest yield of cross-linked products, followed by reaction with Cys and dG. Yields from the other coupling reactions were lower by a factor of 10 or more. Detailed structural examination by NMR and mass spectrometry established that the cross-links between amino acids and single nucleosides involve a formaldehyde-derived methylene bridge. Lys yielded two additional products with dG in which the linking structure is a 1,N(2)-fused triazino ring. The Lys cross-linked products were unstable at ambient temperature. Reactions between the reactive N(alpha)-Boc-protected amino acids and the trinucleotides d(T(1)B(2)T(3)) where B(2) is the target base G, A, or C and reactions between dG, dA and dC and 8-mer peptides containing a single reactive target residue at position 5 yielded cross-linked products with structures inferred from high resolution mass spectrometry and fragmentation patterns that are consistent with those between N(alpha)-Boc-protected amino acids and single nucleotides rigorously determined by NMR studies. These structures will provide a basis for investigation of the characteristics and properties of DPCs formed in vivo and will be helpful in identifying biomarkers for the evaluation of formaldehyde exposure both at the site of contact and at distant sites.

Effect of creatinine and specific gravity normalization on urinary biomarker 1,6-hexamethylene diamine

Urine amine levels used as biomarkers of diisocyanate exposure have usually been normalized with creatinine concentration. The suitability of using creatinine concentration or specific gravity for these biomarkers in exposure assessment has not been established. We investigated the effect of creatinine concentration and specific gravity on urine 1,6-hexamethylene diamine (HDA) levels in multiple mixed linear regression models using quantitative dermal and inhalation exposure data derived from a survey of automotive spray painters occupationally exposed to 1,6-hexamethylene diisocyanate (HDI). Painters' dermal and breathing-zone HDI exposure were monitored for an entire workday for up to three workdays spaced approximately one month apart. One urine sample was collected before the start of work with HDI-containing paints, and multiple samples were collected throughout the workday. Both creatinine concentration and specific gravity were highly significant predictors (p < 0.0001) of urine HDA levels. When these two were used together in the same model, creatinine remained highly significant (p < 0.0001), but specific gravity decreased in significance (p-values 0.10-0.17). We used different individual factors to determine which affected creatinine and specific gravity. Urine collection time was a highly significant predictor of specific gravity (p = 0.003) and creatinine concentration (p = 0.001). Smoker status was significant (p = 0.026) in the creatinine model. The findings indicate that creatinine concentration is more appropriate to account for urine water content than specific gravity and that creatinine is best used as an independent variable in HDI exposure assessment models instead of traditional urine normalization with creatinine concentration.

Quantitative plasma biomarker analysis in HDI exposure assessment

Quantification of amines in biological samples is important for evaluating occupational exposure to diisocyanates. In this study, we describe the quantification of 1,6-hexamethylene diamine (HDA) levels in hydrolyzed plasma of 46 spray painters applying 1,6-hexamethylene diisocyanate (HDI)-containing paint in vehicle repair shops collected during repeated visits to their workplace and their relationship with dermal and inhalation exposure to HDI monomer. HDA was detected in 76% of plasma samples, as heptafluorobutyryl derivatives, and the range of HDA concentrations was < or =0.02-0.92 microg l(-1). After log-transformation of the data, the correlation between plasma HDA levels and HDI inhalation exposure measured on the same workday was low (N = 108, r = 0.22, P = 0.026) compared with the correlation between plasma HDA levels and inhalation exposure occurring approximately 20 to 60 days before blood collection (N = 29, r = 0.57, P = 0.0014). The correlation between plasma HDA levels and HDI dermal exposure measured on the same workday, although statistically significant, was low (N = 108, r = 0.22, P = 0.040) while the correlation between HDA and dermal exposure occurring approximately 20 to 60 days before blood collection was slightly improved (N = 29, r = 0.36, P = 0.053). We evaluated various workplace factors and controls (i.e. location, personal protective equipment use and paint booth type) as modifiers of plasma HDA levels. Workers using a downdraft-ventilated booth had significantly lower plasma HDA levels relative to semi-downdraft and crossdraft booth types (P = 0.0108); this trend was comparable to HDI inhalation and dermal exposure levels stratified by booth type. These findings indicate that HDA concentration in hydrolyzed plasma may be used as a biomarker of cumulative inhalation and dermal exposure to HDI and for investigating the effectiveness of exposure controls in the workplace.

Iminohydantoin lesion induced in DNA by peracids and other epoxidizing oxidants

The oxidation of guanine to 5-carboxamido-5-formamido-2-iminohydantoin (2-Ih) is shown to be a major transformation in the oxidation of the single-stranded DNA 5-mer d(TTGTT) by m-chloroperbenzoic acid (m-CPBA) and dimethyldioxirane (DMDO) as a model for peracid oxidants and in the oxidation of the 5-base pair duplex d[(TTGTT).(AACAA)] with DMDO. 2-Ih has not been reported as an oxidative lesion at the level of single/double-stranded DNA or at the nucleoside/nucleotide level. The lesion is stable to DNA digestion and chromatographic purification, suggesting that 2-Ih may be a stable biomarker in vivo. The oxidation products have been structurally characterized and the reaction mechanism has been probed by oxidation of the monomeric species dGuo, dGMP, and dGTP. DMDO selectively oxidizes the guanine moiety of dGuo, dGMP, and dGTP to 2-Ih, and both peracetic and m-chloroperbenzoic acids exhibit the same selectivity. The presence of the glycosidic bond results in the stereoselective induction of an asymmetric center at the spiro carbon to give a mixture of diastereomers, with each diastereomer in equilibrium with a minor conformer through rotation about the formamido C-N bond. Labeling studies with [(18)O(2)]-m-CPBA and H(2)(18)O to determine the source of the added oxygen atoms have established initial epoxidation of the guanine 4-5 bond with pyrimidine ring contraction by an acyl 1,2-migration of guanine carbonyl C6 to form a transient dehydrodeoxyspiroiminodihydantoin followed by hydrolytic ring-opening of the imidazolone ring. Consistent with the proposed mechanism, no 8-oxoguanine was detected as a product of the oxidations of the oligonucleotides or monomeric species mediated by DMDO or the peracids. The 2-Ih base thus appears to be a pathway-specific lesion generated by peracids and possibly other epoxidizing agents and holds promise as a potential biomarker.

Granulocyte transfusions for pediatric patients and the establishment of national treatment guidelines and donor registry

G-CSF/dexamethasone stimulated donor derived granulocyte transfusion (GTX) has been shown in non-randomized studies to be a useful co-therapy in immune-compromised patients unresponsive to conventional antimicrobial treatments. Reports of GTX are however usually single institution adult experiences. Substantiated pediatric data, other than in neonates, is less common.

Teicoplanin in home therapy of the terminally ill child

Children discharged in the terminal phase of illness were offered the possibility of having central venous line infections treated with teicoplanin at home by their parents after suitable instruction. The decision to begin antibiotic treatment was subjective, based on a history of rigors and/or raised temperature in an otherwise "well" child. No difficulties were encountered in instructing the chosen parents. In all, five treatment periods of 7 days were required in the five children selected. The review time was 31 weeks (mean duration, 6.2 weeks/patient; range, 4-12 weeks), ended in all cases by death. Infection occurred a mean of 3.2 weeks after discharge (range, 1-8 weeks), and all episodes were successfully treated at home without hospital admission or ward-based support. No deaths occurred as a result of antibiotic therapy failure, and there were no clinically relevant side-effects. Autopsy confirmed the absence of central venous line infection in one patient, but blood culture was positive for Staphylococcus aureus in another. This study shows that home treatment of line infections with teicoplanin is effective and well tolerated, and offers advantages in terms of quality of life and parent-child relationships.

Formation of S-[1-(N2-deoxyguanosinyl)methyl]glutathione between glutathione and DNA induced by formaldehyde

Formaldehyde is an essential metabolic intermediate in human cells and can also enter into the body through environmental exposures. It is classified as a human and animal carcinogen according to the International Agency for Research on Cancer (IARC). Previous research has demonstrated that formaldehyde is genotoxic, causing mutations in multiple genes. However, no exogenous formaldehyde-induced DNA adducts have been detected in animals after inhalation exposure, although formaldehyde can result in N(6)-deoxyadenosine, N(2)-deoxyguanosine, and N(4)-deoxycytidine adducts in vitro. This can be partially attributed to the rapid metabolism of formaldehyde by glutathione (GSH)-dependent enzyme systems. Among the intermediates in the pathway of formaldehyde detoxication, S-hydroxymethylglutathione is a reactive species and has the potential to further conjugate with DNA bases. Here, we have demonstrated the formation of S-[1-(N(2)-deoxyguanosinyl)methyl]glutathione between glutathione and DNA in the presence of formaldehyde. This adduct is unique because of the involvement of S-hydroxymethylglutathione which is a key player during the detoxication of formaldehyde.

Oxidative mutagenicity of polar fractions from polycyclic aromatic hydrocarbon-contaminated soils

Soils at hazardous waste sites contain complex mixtures of chemicals and often are difficult to characterize in terms of risk to human and ecological health. Over time, biogeochemical processes can decrease the apparent concentrations of pollutants but also can lead to accumulation of new products for which toxicity and behavior in the environment are largely unknown. A bioassay-directed fractionation technique was used to assess the contribution of redox-active bacterial metabolites to the toxicity of soil contaminated with polycyclic aromatic hydrocarbons (PAHs). A reverse mutation assay with Escherichia coli WP2 uvrA/pKM101 (IC188) and E. coli WP2 uvrA oxyR/pKM101 (IC203) was used to screen fractions for genotoxicity. Strain IC203 carries the delta oxyR30 mutation, which prevents the expression of antioxidant proteins in response to oxidative stress and increases its reversion by compounds that generate reactive oxygen species (ROS). Polar fractions of PAH-contaminated soil extracts were mutagenic to strain IC203 but not to strain IC188, suggesting the involvement of ROS in genotoxicity. Genotoxic potencies ranged from 300 to 1700 revertants per milligram of fraction. Catalase was able to decrease IC203 reversion, implicating the involvement of hydrogen peroxide as a key ROS. Oxidized PAH compounds, including quinones, were identified in the mutagenic fractions but were not by themselves mutagenic. Deasphalted whole extracts and recombined fractions were not mutagenic, indicating that interactions between compounds in different fractions can mitigate genotoxicity.

Quantitative monitoring of dermal and inhalation exposure to 1,6-hexamethylene diisocyanate monomer and oligomers

Respiratory sensitization and occupational asthma are associated with exposure to 1,6-hexamethylene diisocyanate (HDI) in both monomeric and oligomeric forms. The monomer and polymers of diisocyanates differ significantly in their rates of absorption into tissue and their toxicity, and hence may differ in their contribution to sensitization. We have developed and evaluated a liquid chromatography/mass spectrometry (LC-MS) method capable of quantifying HDI and its oligomers (uretidone, biuret, and isocyanurate) in air, tape-stripped skin, and paint samples collected in the automotive refinishing industry. To generate analytical standards, urea derivatives of HDI, biuret, and isocyanurate were synthesized by reaction with 1-(2-methoxyphenyl)piperazine and purified. The urea derivatives were shown to degrade on average by less than 2% per week at -20 degrees C over a 2 month period in occupational samples. The average recovery of HDI and its oligomers from tape was 100% and the limits of detection were 2 and 8 fmol microl(-1), respectively. Exposure assessments were performed on 13 automotive spray painters to evaluate the LC-MS method and the sampling methods under field conditions. Isocyanurate was the most abundant component measured in paint tasks, with median air and skin concentrations of 2.4 mg m(-3) and 4.6 microg mm(-3), respectively. Log-transformed concentrations of HDI (r = 0.79, p < 0.0001) and of isocyanurate (r = 0.71, p < 0.0001) in the skin of workers were correlated with the log-transformed product of air concentration and painting time. The other polyisocyanates were detected on skin for less than 25% of the paint tasks. This LC-MS method provides a valuable tool to investigate inhalation and dermal exposures to specific polyisocyanates and to explore relative differences in the exposure pathways.

Development and application of quantitative methods for monitoring dermal and inhalation exposure to propiconazole

Quantitative methods to measure dermal and inhalation exposure to the fungicide propiconazole were developed in the laboratory and applied in the occupational exposure setting for monitoring five farm workers' exposure during pesticide preparation and application to peach crops. Dermal exposure was measured with tape-strips applied to the skin, and the amount of propiconazole was normalized to keratin content in the tape-strip. Inhalation exposure was measured with an OVS tube placed in the worker's breathing-zone during pesticide handling. Samples were analyzed by GC-MS in EI+ mode (limit of detection 6 pg microl(-1)). Dermal exposure ranged from non-detectable to 32.1 +/- 22.6 ng per microg keratin while breathing-zone concentrations varied from 0.2 to 2.2 microg m(-3). A positive correlation was observed between breathing-zone concentrations and ambient air temperature (r2 = 0.87, p < 0.01). Breathing-zone concentrations did not correlate with dermal exposure levels (r2 = 0.11, p = 0.52). Propiconazole levels were below limit of detection when rubber gloves, coveralls, and full-face mask were used. The total-body propiconazole dose, determined for each worker by summing the estimated dermal dose and inhalation dose, ranged from 0.01 to 12 microg per kg body weight per day. Our results show that tape-stripping of the skin and the OVS can be effectively utilized to measure dermal and inhalation exposure to propiconazole, respectively, and that the dermal route of exposure contributed substantially more to the total dose than the inhalation route.

Prevention of naturally occurring infectious bovine keratoconjunctivitis with a recombinant Moraxella bovis pilin–Moraxella bovis cytotoxin–ISCOM matrix adjuvanted vaccine

To evaluate the efficacy of a recombinant Moraxella bovis pilin-M. bovis cytotoxin subunit vaccine to prevent naturally occurring infectious bovine keratoconjunctivitis (IBK; pinkeye), a randomized, blinded, controlled field trial was conducted during summer 2005 in a northern California herd of beef cattle. One hundred and one steers were vaccinated with ISCOM matrix (adjuvant control), recombinant M. bovis cytotoxin carboxy terminus+ISCOM matrix (MbxA), or recombinant M. bovis pilin-cytotoxin carboxy terminus+ISCOM matrix (pilin-MbxA); calves received secondary vaccinations 21 days later. Calves were examined once weekly for 18 weeks for the development of corneal ulcers associated with IBK. Overall, the pilin-MbxA vaccinated group had the lowest overall cumulative proportion of ulcerated calves. Calves that received MbxA, whether alone or with pilin had significantly higher M. bovis cytotoxin serum neutralizing titers as compared to control calves. Results of ocular cultures suggested that vaccination with an M. bovis antigen affected organism type isolated from an ulcer: M. bovis was cultured more often from the eyes of control calves than from the eyes of calves vaccinated with MbxA and pilin-MbxA. In addition, vaccination of calves with MbxA and pilin-MbxA resulted in a higher prevalence of Moraxella bovoculi sp. nov. in ocular cultures. While no significant difference was observed between a cytotoxin versus pilin+cytotoxin vaccine against IBK, the reduced cumulative proportion of IBK in the pilin-cytotoxin vaccinated calves suggests it may provide an advantage over a cytotoxin vaccine alone. Efficacy of an M. bovis vaccine may be reduced in herds where IBK is associated with M. bovoculi sp. nov.

Relatedness of cytotoxins from geographically diverse isolates of Moraxella bovis

To determine whether amino acid sequence variation exists in the Moraxella bovis (M. bovis) cytotoxin (MbxA) from geographically diverse M. bovis isolated in the United States, mbxA was amplified and sequenced. The MbxA deduced amino acid sequence from M. bovis originally isolated in California, Washington, North Carolina, and Georgia, as well as reference strains of M. bovis isolated at the National Animal Disease Laboratory, Ames, IA, USA, all encoded a nearly identical 927 amino acid protein. MbxA from two of the four California isolates (SFS 9a and SFS 100a) differed from all other isolates at two sites at which the polar amino acids glutamine (position 666) and asparagine (position 823) were replaced by ionized amino acids glutamic acid and aspartic acid, respectively. Rabbit antiserum to the expressed carboxy terminus (amino acids 590-927) of MbxA from M. bovis (Tifton I) neutralized the hemolytic activity of SFS 9a and SFS 100a. The M. bovis cytotoxin appears to be conserved amongst geographically diverse isolates of M. bovis from the USA. Antiserum against the carboxy terminus of MbxA common to the majority of isolates neutralized the hemolytic activity of two strains with a divergent MbxA deduced amino acid sequence. Vaccines against IBK that incorporate MbxA as antigen may offer protection against geographically diverse strains of M. bovis.

Use of conventional and real-time polymerase chain reaction to determine the epidemiology of hemoplasma infections in anemic and nonanemic cats

BACKGROUND

The goals of this study were to develop and apply conventional (c) and real-time TaqMan polymerase chain reaction (PCR) assays for Mycoplasma haemofelis (Mhf), 'Candidatus Mycoplasma haematoparvum' (Mhp), and 'Candidatus Mycoplasma haemominutum' (Mhm) to blood samples of cats to determine the epidemiology of these infections in cats.

HYPOTHESIS

Cats are infected with >2 hemoplasma species, and organism load correlates with disease induced by these organisms.

ANIMALS

Blood samples from 263 anemic and nonanemic cats were used.

METHODS

A retrospective study was conducted.

RESULTS

Forty-seven (18%) samples were positive. Three samples (1%) yielded 170 base pair cPCR products, 1 of which was positive for Mhf using real-time PCR. Forty-four samples (17%) yielded 193 base pair cPCR products, 40 of which were positive for Mhm using real-time PCR. Organism loads ranged from 375 X 10(6)/mL to 6.9 x 10(6)/mL of blood. Sequencing of cPCR products from samples testing negative using real-time PCR identified 2 Mhp-like sequences, 1 Mhm-like sequence, and 1 sequence resembling 'Candidatus Mycoplasma turicensis'. Cats infected with Mhm were less likely to be anemic than uninfected cats. Older age, outdoor exposure, feline immunodeficiency virus (FIV) seropositivity, cutaneous squamous cell carcinoma (SCC), and stomatitis were associated with Mhm infection. Cats from the Sacramento Valley were more often infected with Mhm than cats from the San Francisco bay area.

CONCLUSIONS AND CLINICAL IMPORTANCE

Cats may be infected with 4 hemoplasma species. The association between Mhm infection, FIV, and SCC may reflect outdoor roaming status of infected cats. The clustered distribution of infection suggests an arthropod vector in transmission.

ABO incompatible stem cell transplantation in children does not influence outcome

BACKGROUND

Although delayed red cell engraftment and/or hemolysis have been thoroughly documented in association with ABO incompatibility between donor and recipient in patients undergoing hematopoietic stem cell transplantation (HSCT), there are no studies defining the general, long term clinical outcome in a large group of pediatric patients.

METHODS

We undertook a retrospective single center analysis of children undergoing pediatric allogeneic stem cell transplantation to determine the influence of ABO donor/recipient incompatibility. Outcome was analyzed according to donor type and included survival, graft versus host disease (GvHD), relapse, days of infection, antibiotic use, transfusion requirement and duration of hospital stay.

RESULTS

Two hundred and sixteen children (136 males; 80 females, aged 0-19) transplanted between January 1992 and December 2003 were included in the study. Indications for transplantation were hematological malignancies (n=179) and aplastic conditions (n=37). ABO compatibility was documented in 121 donor/recipient pairs. ABO incompatibility was documented in 95 donor/recipient pairs with 40 major, 40 minor and 15 bi-directional incompatible pairs. ABO incompatibility did not influence survival rate (P=0.3762), the incidence of GvHD (P=0.253) or rate of relapse (P=0.930). Recovery of leucocytes was influenced by ABO incompatibility (P=0.0493), but the rate of infection, transfusion requirements and duration of hospital stay are not.

CONCLUSION

In the pediatric setting, ABO major and/or minor mismatch between donor and recipient did not significantly influence the outcome of HSCT. The choice of donor should be determined by the degree of HLA match and CMV status in preference to ABO blood group compatibility.

Effect of particulate matter air pollution on hospital admissions and medical visits for lung and heart disease in two southeast Idaho cities

Few, if any, published time series studies have evaluated the effects of particulate matter air exposures by combining hospital admissions with medical visit data for smaller populations. We investigated the relationship between daily particulate matter (<10 microm in aerometric diameter or PM10) exposures with admissions and medical visits (emergency room, urgent care, and family practice) for respiratory and cardiovascular disease in Pocatello and Chubbuck, Idaho (population about 60,000), from November 1994 through March 2000. Within generalized linear models, time, weather, influenza, and day-of-week effects were controlled. In single-pollutant models, respiratory disease admissions and visits increased (7.1-15.4% per 50 microg/m3 PM10) for each age group analyzed, with the highest increases in two groups, children and especially the elderly. Statistical analyses suggest that the results probably did not occur by chance. Sensitivity analyses did not provide strong evidence that the respiratory disease effect estimates were sensitive to reasonable changes in the final degrees of freedom choice for time and weather effects. No strong evidence of confounding by NO2 and SO2 was found from results of multi-pollutant models. Ozone and carbon monoxide data were not available to include multi-pollutant models, but evidence suggests that they were not a problem. Unexpectedly, evidence of an association between PM10 with cardiovascular disease was not found, possibly due to the lifestyles of the mostly Mormon study population. Successful time series analyses can be performed on smaller populations if diverse, centralized databases are available. Hospitals that offer urgent or other primary care services may be a rich source of data for researchers. Using data that potentially represented a wide-range of disease severity, the findings provide evidence that evaluating only hospital admissions or emergency room visit effects may underestimate the overall morbidity due to acute particulate matter exposures. Further work is planned to test this conclusion.

Detection of mixed infections with "Candidatus Mycoplasma haemominutum" and Mycoplasma haemofelis using real-time TaqMan polymerase chain reaction

The objective of this study was to evaluate the use of real-time TaqMan PCR assays for detection of coinfections with "Candidatus Mycoplasma haemominutum" (Mhm), and Mycoplasma haemofelis (Mhf), in vitro and over time in experimentally infected cats. First, the ability of each real-time PCR assay to detect and quantify mixed infections was determined in vitro by testing mixtures of plasmids containing Mhm and Mhf 16S rDNA with each assay. Subsequently, 4 specific pathogen-free (SPF) cats, 2 of which were splenectomized, were inoculated with blood from a cat infected with both Mhm and Mhf. Sixteen blood samples were then collected from each cat over a 55-day period. Each of the 64 postinoculation samples was tested using both conventional polymerase chain reaction (cPCR) and real-time PCR for the 16S rRNA gene of each organism. When applied to mixtures of plasmid DNA from each species, the results of quantitation with each of the real-time PCR assays approximately reflected the number of plasmid copies present. Forty-nine of 64 post-inoculation samples (77%) were positive using both cPCR and real-time PCR, 4 (6%) were positive using cPCR only, and 3 (5%) were positive using real-time PCR only. Both organisms were detected in 23 samples using real-time PCR. Mixed infections were not detected using cPCR. The size of the corresponding cPCR products suggested infection with Mhm in 4 and Mhf in 18 of these samples. The use of multiple separate real-time PCR assays rather than cPCR alone should thus be considered for epidemiologic studies of hemoplasmosis in cats.

Identification and characterization of complete RTX operons in Moraxella bovoculi and Moraxella ovis

To determine if Moraxella bovoculi (M. bovoculi), a recently characterized coccoid Moraxella that was isolated from the eyes of calves affected with infectious bovine keratoconjunctivitis (IBK), and Moraxella ovis (M. ovis), originally isolated from sheep with conjunctivitis, possessed genes encoding RTX proteins, genomic DNA was amplified with oligonucleotide primers targeting RTX operon genes of Moraxella bovis (M. bovis). Complete classical RTX operons composed of RTXCABD genes closely linked to a putative secretion accessory protein encoding gene (tolC) were identified in M. bovoculi and M. ovis and were designated mbvCABDtolC and movCABDtolC, respectively. These genes were closely related to M. bovis mbxCABDtolC. Polyclonal rabbit antiserum against the carboxy terminus of M. bovoculi MbvA neutralized hemolytic activity of both M. bovoculi and M. ovis; this antiserum did not neutralize the hemolytic activity of M. bovis. M. bovoculi and M. ovis possess genes that encode proteins related to pathogenic factors of M. bovis.

Moraxella bovoculi sp. nov., isolated from calves with infectious bovine keratoconjunctivitis

Eighteen isolates of a Gram-negative coccus (strain 237T) were cultured from the eyes of dairy and beef calves affected with infectious bovine keratoconjunctivitis (IBK; ‘pinkeye’) in northern California, USA, during summer 2002. These isolates had near full-length (1397 bp) 16S rRNA gene sequences that clustered into three groups with 99.9 % sequence similarity. On the basis of 16S rRNA gene sequence, the isolates were most closely associated with Moraxella bovis and Moraxella ovis in clade I of the classical moraxellae. Biochemically, the novel isolates could be distinguished from the other members of the genus Moraxella isolated from animals on the basis of phenylalanine deaminase activity. The results of partial sequence analysis of six housekeeping genes, the 16S–23S rRNA gene interspacer region and partial 23S rRNA gene provide strong support for the inclusion of these isolates in a novel taxon, for which the name Moraxella bovoculi sp. nov. is proposed. The type strain is strain 237T (=ATCC BAA-1259T=CCUG 52049T).

Identification and quantification of uncultivated Proteobacteria associated with pyrene degradation in a bioreactor treating PAH-contaminated soil

Uncultivated bacteria associated with the degradation of pyrene in a bioreactor treating soil contaminated with polycyclic aromatic hydrocarbons (PAH) were identified by DNA-based stable-isotope probing (SIP) and quantified by real-time quantitative PCR. Most of the 16S rRNA gene sequences recovered from (13)C-enriched DNA fractions clustered phylogenetically within three separate groups of beta- and gamma-Proteobacteria unassociated with described genera and were designated "Pyrene Groups 1, 2 and 3". One recovered sequence was associated with the Sphingomonas genus. Pyrene Groups 1 and 3 were present in very low numbers in the bioreactor but represented 75% and 7%, respectively, of the sequences recovered from 16S rRNA gene clone libraries constructed from (13)C-enriched DNA. In a parallel time-course incubation with unlabelled pyrene, there was between a 2- and 4-order-of-magnitude increase in the abundance of 16S rRNA genes from Pyrene groups 1 and 3 and from targeted Sphingomonas spp. over a 10 day incubation. Sequences from Pyrene Group 2 were 11% of the SIP clone libraries but accounted for 14% of the total bacterial 16S rRNA genes in the bioreactor community. However, the abundance of this group did not increase significantly in response to pyrene disappearance. These data indicate that the primary pyrene degraders in the bioreactor were uncultivated, low-abundance beta- and gamma-Proteobacteria not previously associated with pyrene degradation.

LC/MS/MS method for the quantitation of trans-2-hexenal-derived exocyclic 1,N(2)-propanodeoxyguanosine in DNA

trans-2-Hexenal is an alpha,beta-unsaturated aldehyde to which humans are exposed daily in small amounts. Hexenal has demonstrated mutagenicity and genotoxicity in vitro and reacts with deoxyguanosine to form diastereomeric hexenal-derived exocyclic 1,N(2)-propanodeoxyguanosine (Hex-PdG) adducts. A highly sensitive and specific method for the measurement of Hex-PdG in DNA has not previously been available. An LC/MS/MS assay for the quantitation of Hex-PdG, using [(13)C4(15)N2]Hex-PdG as an internal standard, was developed, to assess binding of hexenal to DNA. Samples were purified prior to analysis by centrifuge filtration and solid phase extraction and analyzed by LC/MS/MS in the selected reaction monitoring (SRM) mode (SRM m/z 366.2 --> 250.2 for Hex-PdG; SRM m/z 372.2 --> 256.2 for [(13)C4(15)N2]Hex-PdG). Recovery of standards was 89% or greater, and quantitation was unaffected by the addition of increasing concentrations of calf thymus DNA (ctDNA). The limit of quantitation, determined in samples of 200 microg of ctDNA spiked with analyte standard, was 0.015 fmol/microg DNA, which corresponds to approximately 5 Hex-PdG/10(9) unmodified nucleotides. Hex-PdG was detected in ctDNA treated with 0.021 microM, 0.21 microM, or 2.1 mM hexenal but not in untreated DNA. Furthermore, Hex-PdG was not detected in DNA exposed to reactive oxygen species-mediated deoxyribose attack and lipid peroxidation, which resulted in a significant increase in the malondialdehyde-derived pyrimido[1,2-a]purin-10(3H)one. Hex-PdG was not detected in DNA of untreated rat liver, but Hex-PdG in hexenal-treated calf thymus DNA was quantifiable when spiked into the rat liver DNA at 0.035 or 0.35 fmol/microg DNA. These data indicate that Hex-PdG is formed following hexenal treatment and that this method is suitable for in vitro or in vivo assessment of Hex-PdG formation.

Tape-strip sampling for measuring dermal exposure to 1,6-hexamethylene diisocyanate

OBJECTIVES

This study describes the development and evaluation of a method for sampling layers of the stratum corneum for the quantitation of dermal exposure to 1,6-hexamethylene diisocyanate (HDI).

METHODS

HDI deposited on skin was collected by the removal of stratum corneum with adhesive tape, derivatized with 1-(2-methoxyphenyl)piperazine, and quantitated as the urea derivative (HDIU) by liquid chromatography-mass spectrometry (LC-MS). This LC-MS method was tested by analyzing tape spiked with HDI-containing products, then applied to tape samples collected from the skin of an auto-body shop worker exposed to polyurethane paint aerosols.

RESULTS

The limits of detection and quantitation were 20 and 50 fmol per injection, respectively. The recovery of HDI from the tape was 99.3% [95% confidence interval (95% CI) 97.1-102]. HDIU was stable at -40 degrees C, degrading by 0.28% (95% CI 0.10-0.46) per day. Quantifiable amounts of HDI were observed in 42.6% of the first three successive tape-strip samples collected from 36 different sites on the skin of the worker. The amount of HDI recovered from the collection sites on skin, measured by summing the levels collected with three successive tape-strips, ranged from nondetectable to 1874 pmol.

CONCLUSIONS

This study demonstrates that HDI on skin can be collected with tape-strips and quantified at occupational levels using LC-MS.

Photoinactivation of hepatitis A virus by synthetic porphyrins

Porphyrins are photosensitizers and may be applicable in situations where viral inactivation is required, as for in vitro inactivation of nonenveloped viruses in blood components or in other aqueous media. No study has examined the efficacy of porphyrin inactivation on human pathogens such as hepatitis A virus (HAV) in plasma or other liquids. Experiments were conducted to evaluate the effect of synthetic porphyrins on HAV in porphyrin-containing human plasma and phosphate-buffered saline exposed to long-wavelength (365 nm) UV light. Inactivation of bacteriophage MS2 (MS2) also was determined in some trials. Solutions containing cationic, anionic or amphiphilic porphyrins irradiated with an average light dose of 4.3 J/cm(2) for 90 min resulted in >3 log(10) (>99.9%) to >4 log(10) (>99.99%) inactivation of both HAV and MS2. Viral inactivation may have been greater than observed because the limits of detection of the assay had been reached. Under ambient lighting conditions, none of the porphyrins was mutagenic in the Ames assay and only the congener with the longest chain-length, tetrakis (N-[n-hexadecyl]-4-pyridiniumyl) porphyrin, was appreciably toxic to mammalian cells. Disinfection by photoactivated synthetic porphyrins therefore can offer an effective and relatively safe approach to removal of nonenveloped viruses from aqueous media.

A 2-Iminohydantoin from the Oxidation of Guanine

The nucleobase guanine was oxidized with dimethyldioxirane (DMDO) to explore the role of epoxidizing agents in oxidative DNA damage. Treatment of guanine with 10% molar excess DMDO in aqueous solution at 0 degrees C and pH 7.5 followed by workup under mild conditions gave 5-carboxamido-5-formamido-2-iminohydantoin (1) as the sole isolable product in 71% yield. The structure of 1 was established on the basis of mass spectrometry and NMR studies on 1 and its isotopomers generated by the oxidation of [4-(13)C] and [7-(15)N]guanine, which yield [5-(13)C]1 and [7-(15)N]1. The distribution of 13C and 15N labels in the isotopomeric products supports initial epoxidation of the C4-C5 bond of guanine followed by a 1,2-acyl migration of guanine C6. Compound 1 is suggested as a possible primary DNA lesion from putative epoxidizing agents, including hydroperoxides present during biological processes such as lipid peroxidation.