Dinitrogen oxide production by a mixed culture of nitrifying bacteria during ammonia shock loading and aeration failure

A number of experiments was conducted in order to establish if N₂O in the exhaust gas from an aerobic consortium of nitrifiers could be used as an indicator for monitoring the nitrification process. Laboratory-scale experiments with an activated sludge system showed a strong correlation between ammonia shock loads and both the concentration of N₂O and the rate of increase of N₂O in the exhaust gas for shock loads less than 1.60 mg ammonical nitrogen (NH₃-N) per g total suspended solids (TSS). For greater ammonia shock loads, correlation was found between build-up of nitrite in the aeration tank and the concentration of N₂O in the exhaust gas from the tank. When subjecting the system to aeration failure, a similar pattern was seen, with a correlation between nitrite build-up in the aeration tank and increases in the concentration of N₂O in the exhaust gas. The results from this work suggest that the changes in N₂O concentration in the exhaust gas from a nitrifying process may be a useful parameter for monitoring such processes. Received 15 October 2001/ Accepted in revised form 05 June 2002     

High initiation and long duration of breastfeeding despite absence of early skin-to-skin contact in Karen refugees on the Thai-Myanmar border: a mixed methods study

Background

Early skin-to-skin contact (SSC) after birth is recommended as part of the United Nations Children’s Fund (UNICEF) baby friendly health initiative to promote optimum breastfeeding. This paper reports rates of breastfeeding initiation and duration in a low resource environment, where early SSC is not practised, and explores views of pregnant women and midwives surrounding breastfeeding and swaddling.

Methods

Data from records from a single hospital on the Thai-Myanmar border where refugee women gave birth during a one-year period (2010) were used to determine breastfeeding initiation rates and the time of the first breastfeed, and duration of breastfeeding of the previous alive child in multigravidae. Focus group discussions (FGD) were conducted to obtain information from pregnant women attending antenatal care about their intended or previous duration of breastfeeding and views on breastfeeding. Interviews with local midwives explored reasons for high rates of breastfeeding in this setting and the practice of newborn swaddling.

Results

Of 1404 live births in 2010 in Maela refugee camp there were 982 evaluable mother-newborn pairs, including 80 infants born before 37 weeks gestation. Initiation of breastfeeding within the first hour after birth and exclusive breastfeeding at discharge in term mother-newborn pairs was 91.2% (823/902) and 99.3% (896/902); and before 37 weeks gestation, 48.8% (39/80) and 98.8% (79/80). Reported duration of previous breastfeeding was 19 (range 2 to 72) months.During FGD all primigravidae (n?=?17) intended to breastfeed and all multigravidae (n?=?33) had previously breastfed; expected or previous duration of feeding was for more than one year or longer. The major theme identified during FGD was breastfeeding is “good”. Women stated their intention to breastfeed with certainty. This certainty was echoed during the interviews with midwifery staff. SSC requires a delay in early swaddling that in Karen people, with animistic beliefs, could risk loss of the spirit of the newborn or attract malevolent spirits.

Conclusions

In a population with a strong culture of breastfeeding and robust breastfeeding practices, high rates of initiation and duration of breastfeeding were found despite a lack of early skin-to-skin contact. Local preferences, traditions and practices that protect, support and maintain high rates of breastfeeding should be promoted.

     

Preface

Reviews in Environmental Science and Bio/Technology -     

Diversity and Abundance of Zoonotic Pathogens and Indicators in Manures of Feedlot Cattle in Australia

The occurrence of 10 pathogens and three fecal indicators was assessed by quantitative PCR in manures of Australian feedlot cattle. Most samples tested positive for one or more pathogens. For the dominant pathogens Campylobacter jejuni, Listeria monocytogenes, Giardia spp., Cryptosporidium spp., and eaeA-positive Escherichia coli, 10² to 10⁷ genome copies g⁻¹ (dry weight) manure were recovered.More than 600,000 tons of feedlot cattle manure are generated each year in Australia, which raises concern for potential water, air, and soil contamination (21, 27). Hence, better monitoring and knowledge of the resulting risks are needed (5, 26). Most zoonotic pathogens associated with cattle are well described in the literature, especially those of major health significance, including the bacterial pathogens Campylobacter spp., Listeria monocytogenes, pathogenic Escherichia coli (particularly serotypes O157 and O111), Salmonella enterica, Yersinia spp., Leptospira spp., Coxiella burnetii, Mycobacterium avium subsp. paratuberculosis, and the parasitic protozoa Giardia lamblia and Cryptosporidium parvum (2, 21, 27). While studies of pathogen occurrence in manure are numerous, data suited to quantitatively estimating end user risks are still limited. Few surveys quantify multiple pathogens (11, 12, 14, 28), and none have concurrently measured all 10 above in cattle manure. A further constraint on risk assessment is that most data were generated in North America or Europe, where cli-mate and environment can differ markedly from Australian conditions.Addressing this knowledge gap now appears feasible, as real-time quantitative PCR (qPCR) can be used as an alternative to culture-based methods for quantifying environmental pathogens (7, 23, 29). Improvements in sample preparation and nucleic acid cleanup methods have largely overcome problems associated with the molecular biology-based analysis of fecal matter (22). Further, qPCR can detect stressed, damaged, and otherwise nonculturable cells persisting in a state of dormancy or indeed dead (15, 17, 29). The aim of this paper is to report on a quantitative survey of zoonotic pathogens and indicators in manures from Australian feedlot beef cattle.A total of 128 composited samples (five subsamples each) representing fresh feces (n = 32), pen manure (n = 32), harvested pen manure (n = 28), stockpiled manure (n = 23), composted manure (n = 6), and carcass compost (n = 7) were collected from five cattle feedlots in eastern Australia in the winter/summer of 2009 (13). All samples were assayed for the 10 key pathogens listed above and also fecal indicators (total coliforms, E. coli, and enterococci).     

NVP-LDE225, a Potent and Selective SMOOTHENED Antagonist Reduces Melanoma Growth In Vitro and In Vivo

Melanoma is one of the most aggressive cancers and its incidence is increasing worldwide. So far there are no curable therapies especially after metastasis. Due to frequent mutations in members of the mitogen-activated protein kinase (MAPK) signaling pathway, this pathway is constitutively active in melanoma. It has been shown that the SONIC HEDGEHOG (SHH)-GLI and MAPK signaling pathway regulate cell growth in many tumors including melanoma and interact with each other in the regulation of cell proliferation and survival.Here we show that the SHH-GLI pathway is active in human melanoma cell lines as they express downstream target of this pathway GLI1. Expression of GLI1 was significantly higher in human primary melanoma tissues harboring BRAF^V600E mutation than those with wild type BRAF. Pharmacologic inhibition of BRAF^V600E in human melanoma cell lines resulted in decreased expression of GLI1 thus demonstrating interaction of SHH-GLI and MAPK pathways. Inhibition of SHH-GLI pathway by the novel small molecule inhibitor of smoothened NVP-LDE225 was followed by inhibition of cell growth and induction of apoptosis in human melanoma cell lines, interestingly with both BRAF^V600E and BRAF^{Wild Type} status. NVP-LDE225 was potent in reducing cell proliferation and inducing tumor growth arrest in vitro and in vivo, respectively and these effects were superior to the natural compound cyclopamine.Finally, we conclude that inhibition of SHH-GLI signaling pathway in human melanoma by the specific smoothened inhibitor NVP-LDE225 could have potential therapeutic application in human melanoma even in the absence of BRAF^V600E mutation and warrants further investigations.     

Inactivation of indicators and pathogens in cattle feedlot manures and compost as determined by molecular and culture assays

Accurate and conservative information about pathogen inactivation rates is needed as the basis for safe manure management on beef cattle feedlots. The survival of indicators and pathogens in faecal pen manure, stockpiled manure and manure compost was measured with autochthonous indicator bacteria (Escherichia coli, Clostridium perfringens, enterococci, total coliforms) and pathogens (Listeria monocytogenes, Campylobacter jejuni) using culture and/or real-time quantitative PCR (qPCR) methods. Additionally, the manures were incubated at 20, 37, 50 and 60 °C in microcosms to quantify the persistence of autochthonous microorganisms and selected process performance surrogates (Clostridium sporogenes, green fluorescent protein-labelled E. coli and L. monocytogenes). Estimated qPCR cell counts indicated that up to four orders of magnitude more target cells were present compared with the culturable counts. Corresponding T(90) estimates were up to sixfold higher. This study demonstrates the benefits of nucleic acid-based quantification of pathogen inactivation in cattle manures and concludes that the concurrent analysis of microorganisms by molecular and culture methods provides complementary value.     

Activated sludge biotreatment of sulphurous waste emissions

Odours from wastewater treatment plants are comprised of a mixture of various gases, of which hydrogen sulphide (H₂S) is the main constituent. Sulphurous compounds can be degraded by microorganisms commonly found in wastewater. The use of activated sludge (AS) diffusion as a dual-role system, for the treatment of wastewater and for odour control, offers an alternative to traditional sulphurous waste gas treatment processes, such as biofilters, bioscrubbers and biotrickling filters, both in practical terms (use of existing facilities) and economically (minimal capital cost). Activated sludge diffusion avoids the common problems associated with these processes such as media plugging, excess biomass accumulation, gas short-circuiting, and moisture control and maintaining the correct biofilm thickness. The design issues to be considered when using AS diffusion for odour abatement, comprise odourous air pre-treatment,blowers and diffuser types, corrosion protection and increase in odour emission intensity. Nitrification inhibition depends on the composition and acclimation of the biomass, the concentration of H₂S and other components of the wastewater. Hydrogen sulphide removal rates of >98% were consistently achieved for loads of 3–34 mg H₂S/g MLSS/h, in two case studies, which also showed that sludge type has an impact on the ability of the sludge to degrade H₂S. Wastewater process performance measured as five-day biological oxygen demand (BOD₅), chemical oxygen demand (COD) and effluent suspended solids removal was not affected by H₂S diffusionat 5 ppm. A change in the microorganism population dynamics of anactivated sludge was observed when it was exposed to H₂S for aperiod of more than 21 days.     

Selective inhibition of vitamin D hydroxylases in human keratinocytes

Human keratinocytes convert 25(OH)D(3) to hormonally active 1alpha,25(OH)(2)D(3) and respond to its antiproliferative/prodifferentiating action in vitro and in vivo. Levels and activity of 1alpha,25(OH)(2)D(3) are short-lived. 1alpha,25(OH)(2)D(3) induces 24-hydroxylase (CYP24) that rapidly metabolizes the hormone, yielding a cascade of side-chain oxidized products and this eventually results in the loss of activity. Aiming at stabilizing the levels of active hormone, we have searched for potent, selective inhibitors of CYP24. Selective inhibition was crucial in order to avoid impairment of 1alpha,25(OH)(2)D(3) synthesis, catalyzed by 1alpha-hydroxylase - a related member of cytochrome P-450 (CYP) superfamily. We describe here the testing protocol, using primary human keratinocyte cultures as an appropriate source of CYP24 and 1alpha-hydroxylase, (3)H-25(OH)D(3) (at physiological concentrations) as substrate and sensitive HPLC techniques to analyze the complex metabolite profiles. Four hundred potential inhibitors were screened by this method; most of them were synthesized in our laboratory. These compounds (entitled azoles) were capable of direct binding to the heme iron and of additional interactions with other parts of the enzyme. In this paper, we present VID400 and SDZ 89-443, as first examples of powerful selective CYP24 inhibitors. As anticipated, these compounds increased the levels of 1alpha-hydroxylated products generated from (3)H-25(OH)D(3) and extended their lifetime. Importantly, blocking of 24-hydroxylation led to a switch in metabolism, namely to preferential conversion of 1alpha,25(OH)(2)D(3) to 1alpha,25(OH)(2)-3epi-D(3). As spin-off from our program, selective inhibitors of 1alpha-hydroxylase were also found (e.g. SDZ 88-357). Using (3)H-25(OH)D(3) as substrate in the absence of SDZ 88-357, CYP24 showed high preference for freshly generated 1alpha-hydroxylated metabolites over abundant 25(OH)D(3). In the presence of SDZ 88-357, we noticed a great increase in 24-hydroxylation of (3)H-25(OH)D(3). Besides their use as valuable tools in elucidating regulatory mechanisms, inhibitors of VD hydroxylases may give rise to novel therapeutic strategies, especially in defects of cell growth and differentiation.     

Nitrous oxide monitoring for nitrifying activated sludge aeration control: a simulation study

An activated sludge aeration control concept was developed utilizing off-gas nitrous oxide concentrations as a surrogate for autotrophic nitrifying bacterial inhibition and aeration air as a master control variable. The control concept was evaluated using a simulated pilot scale bioreactor (mathematically calibrated liquid phase process model and a model to link off-gas nitrous oxide generation to liquid phase conditions) as a data generator. When applied to the simulated system, the process controller was successful at maintaining the process at the desired operating setpoint and promoting stable operation by minimizing periods of significant inhibition. Furthermore, it provided a more efficient use of the air supplied to the bioreactor during periods of varying feed loading by matching the air supply to the metabolic demands, substantially reducing periods of over and under-aeration. The findings of this research demonstrate the potential for off-gas nitrous oxide monitoring as a completely non-invasive alternative to liquid phase monitoring used in conventional dissolved oxygen control. Investigations are currently underway at the laboratory scale to evaluate the benefits and limitations associated with this control concept, with particular emphasis on implementation issues and the quantification of potential aeration and cost savings.