Characterising urban zinc generation to identify surface pollutant hotspots in a low intensity rainfall climate.

Characterising stormwater runoff quality provides useful insights into the dynamics of pollutant generation and wash off rates. These can be used to prioritise stormwater management strategies. This study examined the effects of a low intensity rainfall climate on zinc contributions from different impermeable urban surface types. First flush (FF) and steady state samples were collected from seven different surfaces for characterisation, and the data were also used to calibrate an event-based pollutant load model to predict individual 'hotspot' surfaces across the catchment. Unpainted galvanised roofs generated very high concentrations of zinc, primarily in the more biologically available dissolved form. An older, unpainted galvanised roof had FF concentrations averaging 32,338 µg/L, while the new unpainted roof averaged 4,782 µg/L. Roads and carparks also had elevated zinc, but FF concentrations averaged only 822-1,584 µg/L. Modelling and mapping expected zinc loads from individual impermeable surfaces across the catchment identified specific commercial roof surfaces to be targeted for zinc management. The results validate a policy strategy to replace old galvanised roof materials and avoid unpainted galvanised roofing in future urban development for better urban water quality outcomes. In the interim, readily-implemented treatment options are required to help mitigate chronic zinc impacts on receiving waterways.

A novel modelling framework to prioritize estimation of non-point source pollution parameters for quantifying pollutant origin and discharge in urban catchments.

Stormwater runoff in urban catchments contains heavy metals (zinc, copper, lead) and suspended solids (TSS) which can substantially degrade urban waterways. To identify these pollutant sources and quantify their loads the MEDUSA (Modelled Estimates of Discharges for Urban Stormwater Assessments) modelling framework was developed. The model quantifies pollutant build-up and wash-off from individual impervious roof, road and car park surfaces for individual rain events, incorporating differences in pollutant dynamics between surface types and rainfall characteristics. This requires delineating all impervious surfaces and their material types, the drainage network, rainfall characteristics and coefficients for the pollutant dynamics equations. An example application of the model to a small urban catchment demonstrates how the model can be used to identify the magnitude of pollutant loads, their spatial origin and the response of the catchment to changes in specific rainfall characteristics. A sensitivity analysis then identifies the key parameters influencing each pollutant load within the stormwater given the catchment characteristics, which allows development of a targeted calibration process that will enhance the certainty of the model outputs, while minimizing the data collection required for effective calibration. A detailed explanation of the modelling framework and pre-calibration sensitivity analysis is presented.

Contaminant removal and hydraulic conductivity of laboratory rain garden systems for stormwater treatment.

In order to evaluate the influence of substrate composition on stormwater treatment and hydraulic effectiveness, mesocosm-scale (180 L, 0.17 m(2)) laboratory rain gardens were established. Saturated (constant head) hydraulic conductivity was determined before and after contaminant (Cu, Zn, Pb and nutrients) removal experiments on three rain garden systems with various proportions of organic topsoil. The system with only topsoil had the lowest saturated hydraulic conductivity (160-164 mm/h) and poorest metal removal efficiency (Cu ≤ 69.0% and Zn ≤ 71.4%). Systems with sand and a sand-topsoil mix demonstrated good metal removal (Cu up to 83.3%, Zn up to 94.5%, Pb up to 97.3%) with adequate hydraulic conductivity (sand: 800-805 mm/h, sand-topsoil: 290-302 mm/h). Total metal amounts in the effluent were <50% of influent amounts for all experiments, with the exception of Cu removal in the topsoil-only system, which was negligible due to high dissolved fraction. Metal removal was greater when effluent pH was elevated (up to 7.38) provided by the calcareous sand in two of the systems, whereas the topsoil-only system lacked an alkaline source. Organic topsoil, a typical component in rain garden systems, influenced pH, resulting in poorer treatment due to higher dissolved metal fractions.

Placental haemozoin and malaria in pregnancy.

Malaria infections in pregnant women cause poor birth outcomes. Malaria pigment (haemozoin) accumulates in the placenta within macrophages and extracellularly, but its pathological significance is not understood. In order to study the potential role of haemozoin in malaria pathogenesis, we enrolled primigravid women at a Malawian government antenatal clinic and followed them through delivery. One hundred and thirteen women (71 per cent) out of 159 women followed through delivery were parasitaemic at least once. Mean placental haemozoin concentrations were significantly higher in women with delivery parasitaemias (223 ng/mg protein) than in women who never had a detectable parasitaemia (43 ng/mg protein; P<0.05), but were not significantly higher in women who were parasitaemic only during the antenatal period (67 ng/mg protein). Haemozoin was not associated with preterm delivery (PTD) or intrauterine growth retardation (IUGR) (P -values, 0.307-0.787). Thus, placental haemozoin is associated with malaria infection at the time of delivery and does not seem to be associated with poor birth outcome.

An analysis of the mutagenicity of 1,2-dibromoethane to Escherichia coli: influence of DNA repair activities and metabolic pathways.

The mutagenicity of 1,2-dibromoethane (EDB) to Escherichia coli was reduced by the UV light-induced excision repair system but unaffected by the loss of a major apurinic/apyrimidinic site repair function. At high doses, 70-90% of the EDB-induced mutations were independent of SOS-mutagenic processing and approximately 50% were independent of glutathione conjugation. The SOS-independent mutations induced by EDB were unaffected by the enzymes that repair alkylation-induced DNA lesions. EDB-induced base substitutions were dominated by GC to AT and AT to GC transitions. These results suggest that EDB-induced premutagenic lesions have some, but not all, of the characteristics of simple alkyl lesions.

Splenic and hepatic hemozoin in mice after malaria parasite clearance.

Hemozoin (malaria pigment) is found in many tissues during malaria infections. In mice that have self-cured from Plasmodium yoelii and Plasmodium chabaudi infections, liver hemozoin concentration and total content decreased for 6-9 mo after parasite clearance. However, both spleen hemozoin concentration and total hemozoin content increased dramatically during this time period. Thus, hemozoin or hemozoin-laden macrophages continue to accumulate in murine spleens for at least several months after malaria parasitemia becomes undetectable.

Haemozoin: identification and quantification.

Haemozoin (malaria pigment) is a haem polymer resulting from the breakdown of haemoglobin by Plasmodium spp. This refractory substance has been the focus of many studies and of much debate, mainly because of its role in the pharmacological activity of certain antimalarials. Haemozoin is also important because its presence in tissues serves as an indicator of malaria infections, and may itself be a mediator of malaria pathogenesis. In this article, Amy Sullivan and Steven Meshnick review the structure and synthesis of haemozoin, and then focus on methods of haemozoin identification in tissue. This latter aspect has implications for the study of haemozoin both as an indicator of malaria infection and as a possible mediator of malaria pathogenesis.

Interactions between epsilon, the proofreading subunit of DNA polymerase III, and proteins involved in the SOS response of Escherichia coli.

Epsilon, a fidelity subunit of Escherichia coli DNA Polymerase III, is encoded by dnaQ+. dnaQ49 is a recessive allele that confers temperature-sensitive and salt-suppressible phenotypes for both replication fidelity and viability. SOS mutagenesis in E. coli is regulated by LexA and requires activated RecA (RecA*) and the products of the umuDC operon. dnaQ49 strains with various recA, lexA and umuDC alleles were constructed to determine if activities induced as part of the SOS response influence epsilon activity. We found: (1) both UmuDC and RecA* independently enhance the dnaQ49 mutator phenotype, and (2) expression of RecA* activity in the absence of UmuDC function increases the temperature sensitivity for viability of dnaQ49. These results support the hypothesis that RecA and one or both of the UmuDC proteins interact with the replication complex during SOS mutagenesis.

The coreceptor mutation CCR5Delta32 influences the dynamics of HIV epidemics and is selected for by HIV.

We explore the impact of a host genetic factor on heterosexual HIV epidemics by using a deterministic mathematical model. A protective allele unequally distributed across populations is exemplified in our models by the 32-bp deletion in the host-cell chemokine receptor CCR5, CCR5Delta32. Individuals homozygous for CCR5Delta32 are protected against HIV infection whereas those heterozygous for CCR5Delta32 have lower pre-AIDS viral loads and delayed progression to AIDS. CCR5Delta32 may limit HIV spread by decreasing the probability of both risk of infection and infectiousness. In this work, we characterize epidemic HIV within three dynamic subpopulations: CCR5/CCR5 (homozygous, wild type), CCR5/CCR5Delta32 (heterozygous), and CCR5Delta32/CCR5Delta32 (homozygous, mutant). Our results indicate that prevalence of HIV/AIDS is greater in populations lacking the CCR5Delta32 alleles (homozygous wild types only) as compared with populations that include people heterozygous or homozygous for CCR5Delta32. Also, we show that HIV can provide selective pressure for CCR5Delta32, increasing the frequency of this allele.

Patterns of haemozoin accumulation in tissue.

A sensitive fluorometric method for assaying malarial pigment, haemozoin, has been developed and used to determine the haemozoin content of blood and tissue samples. Plasmodium falciparum rings and trophozoites were found to contain 23 and 339 ng haemozoin/10(6) parasitized red blood cells (PRBCs), respectively. Unsynchronized Plasmodium berghei NK65 or ANKA parasites from infected mice contained 27 and 61 ng haemozoin/10(6) PRBCs, respectively. An exponential accumulation of haemozoin within 18 days after infection was demonstrated in liver and spleen tissue, representing up to 0.2% of the tissue by wet weight by day 18. Histology indicated that the accumulation occurred predominantly in the tissue monocytes. In the brain, the levels of haemozoin after 8 days of infection were considerably lower than they were in the liver or spleen, and most of the pigment appeared to be that present inside parasitized red blood cells. CBA/Ca mice infected with P. berghei ANKA (a cerebral malaria model) had significantly higher amounts of haemozoin in the brain than did ICR mice infected with P. berghei NK65. Thus, haemozoin levels in tissue increase with the duration of infection, and its presence may be associated with cerebral pathology.

Presence of the dnaQ-rnh divergent transcriptional unit on a multicopy plasmid inhibits induced mutagenesis in Escherichia coli.

In Escherichia coli the dnaQ+ gene, which encodes epsilon, a fidelity subunit of DNA polymerase III, and the rnh+ gene, which encodes RNase H, share a promoter region but are transcribed in opposite directions. The presence of this divergent transcriptional unit on a multicopy plasmid inhibited by as much as 10-fold mutations induced by the SOS-dependent mutagens methyl methanesulfonate and UV light. Mutations in either gene eliminated the effect, suggesting that both genes contribute either directly or indirectly to the antimutagenic phenotype. Neither survival to mutagen exposure nor induction of the SOS response was comparably affected by the presence of the genes. Although the antimutagenic phenotype was partially suppressed by excess UmuDC proteins, which are required for SOS mutagenesis, the presence of the dnaQ+-rnh+ clone also reduced the induction of mutations by N-methyl-N'-nitro-N-nitrosoguanidine in cells deficient for SOS mutagenic processing. The results suggest that the presence of the dnaQ+-rnh+ divergent transcriptional unit interferes with an underlying mutagenic mechanism that is normally facilitated by the proteins induced as part of the SOS response.

Legalized physician-assisted suicide in Oregon--the second year.

BACKGROUND AND METHODS: In 1997, Oregon legalized physician-assisted suicide. We have previously reported data on terminally ill Oregon residents who received prescriptions for lethal medications under the Oregon Death with Dignity Act and who died in 1998. We now report similar data for 1999, obtained from physicians' reports, death certificates, and interviews with physicians. We also report data from interviews with family members. RESULTS: Information on 33 persons who received prescriptions for lethal medications in 1999 was reported to the Oregon Health Division; 26 died after taking the lethal medications, 5 died from their underlying illnesses, and 2 were alive as of January 1, 2000. One additional patient, who received a prescription in 1998, died after taking the medication in 1999. Thus, 27 patients died after ingesting lethal medications in 1999 (9 per 10,000 deaths in Oregon), as compared with 16 patients in 1998 (6 per 10,000). The median age of the 27 patients who died in 1999 after taking lethal medications was 71 years. The most frequent underlying illnesses were cancer (in 17 patients), amyotrophic lateral sclerosis (in 4), and chronic obstructive pulmonary disease (in 4). All 27 patients had health insurance, 21 were receiving hospice care, and 13 were college graduates. According to both physicians and family members, patients requested assistance with suicide for several reasons, including loss of autonomy, loss of control of bodily functions, an inability to participate in activities that make life enjoyable, and a determination to control the manner of death. CONCLUSIONS: In the second as compared with the first year of legalized physician-assisted suicide in Oregon, the number of patients who died after ingesting lethal medications increased, but it remained small in relation to the total number of persons in Oregon who died. Patients who request assistance with suicide appear to be motivated by several factors, including loss of autonomy and a determination to control the way in which they die.

Malaria infection during pregnancy: intrauterine growth retardation and preterm delivery in Malawi.

In sub-Saharan Africa, malaria infection in pregnancy contributes to low birth weight through intrauterine growth retardation (IUGR) and preterm delivery (PTD). It was hypothesized that malaria-associated PTD and IUGR have differing etiologies due to timing of infection. In a prospective cohort of primigravid women enrolled at the antenatal clinic of Mangochi District Hospital in Malawi, the associations were investigated between antenatal or delivery parasitemias and IUGR or PTD. Among 178 singleton deliveries, 35% of infants were preterm or had IUGR. Cord blood parasitemia (odds ratio [OR]=3.34; 95% confidence interval [CI], 1.3-8.8], placental parasitemia (OR=2.43; 95% CI, 1.2-5.1), and postdelivery maternal peripheral parasitemia (OR=2.78; 95% CI, 1.3-6.1) were associated with PTD. Parasitemia and/or clinically diagnosed malaria in the antenatal period was associated with IUGR (OR=5.13; 95% CI, 1.4-19.4). Delivery parasitemias had borderline associations with IUGR. The risk patterns observed suggest that the timing and severity of infection influences the occurrence of IUGR or PTD.

Malaria and pregnancy: placental cytokine expression and its relationship to intrauterine growth retardation.

Malaria infections during pregnancy can lead to the delivery of low-birth-weight infants. In this study, cytokine mRNA was measured in placentas from 23 malaria-infected and 21 uninfected primigravid women who had delivered in Mangochi, Malawi, a region with a high rate of transmission of falciparum malaria. Significantly increased expression of interleukin (IL)-1beta, IL-8, and tumor necrosis factor (TNF)-alpha and decreased expression of IL-6 and transforming growth factor-beta1 were found in malaria-infected compared with uninfected placentas. TNF-alpha and IL-8 were produced by maternally derived hemozoin-laden placental macrophages. Increased TNF-alpha expression was associated with increased placental hemozoin concentrations. Increased TNF-alpha or IL-8 expression in the placenta was associated with intrauterine growth retardation but not with preterm delivery. The results suggest that malaria infections induce a potentially harmful proinflammatory response in the placenta.

TNF-alpha promoter single nucleotide polymorphisms are markers of human ancestry.

We present a map of single nucleotide polymorphisms (SNPs) in the human tumor necrosis factor (TNF)-alpha promoter based upon exploratory sequencing of 333 human TNF-alpha gene promoters from individuals of distinct ancestral backgrounds. We detect 10 TNF-alpha promoter SNPs that occur with distinct frequencies in populations of different ancestry. Consistent with these findings, we show that two TNF-alpha SNPs, the -243 SNP and the -856 SNP, are the first SNP markers of a sub-Saharan African-derived extended haplotype and an Amerindian HLA haplotype, respectively. Comparisons of TNF-alpha promoter SNP allele frequencies can thus help elucidate variation of HLA haplotypes and their distribution among existing ethnic groups and shed light into the history of human populations.