OECD 414 supplementary prenatal developmental toxicity study of sodium molybdate dihydrate in the rat and benchmark dose evaluation.

In a continuing investigation of the potential for reproductive and developmental toxicity of molybdenum (Mo), consequent to the previous published OECD studies [1,2] and as directed by the European Chemicals Agency [3], a supplemental rat GLP-compliant Prenatal Developmental Toxicity (PNDT) study was conducted to investigate higher dose levels of sodium molybdate dihydrate (SMD) in an identical study design (OECD 414)[4] to Murray et al. 2014a [1], at dietary concentrations calculated to provide target Mo levels of 80 and 120 mg/kg bw/day (the maximum-tolerated dose). There was no effect on post-implantation loss, litter size, sex ratio or the incidence of external, visceral or skeletal fetal malformations or variations. Fetal weight was reduced proportionate to maternal dose. Minimal differences observed in the ossification status of some extremities of fetuses from females receiving 120 mg Mo/kg bw/day were confirmed as transient by skeletal examination of PND 21 pups from a further group of females receiving the same dose regime. There was no evidence of copper depletion in serum, placenta or liver. A benchmark dose evaluation using continuous and dichotomous approaches by combining the fetal body weight data from this study and the previous study determined that the BMD05 ranged from 47 to 57 mg Mo/kg bw/day, depending on the modelling approach and the BMDL05 estimates ranged from 37 to 47 mg Mo/kg bw/day. These levels are considered a more statistically robust point of departure for risk assessment for reproductive effects than the established NOAEL of 40 mg Mo/kg bw/day.

Risk factors associated with Salmonella status of broiler flocks delivered to grow-out farms.

In a prospective field observational study in the southeastern USA, we sampled gastrointestinal (GI) tracts from chicks of 65 broiler flocks delivered to conventional grow-out farms for rearing. The flocks were hatched at seven broiler hatcheries. The mean within-flock prevalence of Salmonella-positive samples was 6.5% and ranged from 0% to 86.7%. Of the 65 flocks studied, 25 (38.5%) had at least one Salmonella-positive sample. Accounting for confounding variability among the hatcheries and broiler companies, we tested whether the probability of detecting Salmonella in GI tracts of the chicks delivered was associated with certain characteristics of parent breeder flocks; hatchery production volume; hatchery ventilation system; hatchery egg-room conditions; egg incubation, candling, hatching, eggshell and bird separation, and bird-processing procedures; management of hatchery-to-farm transportation; day of week of hatch; weather conditions during transportation; or season of the hatch. Two risk factor models were adopted. The first model indicated that a greater number of parent flocks, manual separation of eggshell and bird, and a greater amount of fluff and feces on tray liners used during hatchery-to-farm transportation at delivery were associated with increased probability of detecting Salmonella in chick GI tracts, whereas a greater number of birds in the delivery vehicle was associated with decreased probability. The second model indicated that broiler flocks hatched on Tuesdays versus either Mondays or Thursdays (with no hatches on Wednesdays, Fridays or week-ends), increased average hatchability of the eggs from the parent flocks, and greater amounts of fluff and feces on the transport tray liners at delivery were all associated with increased probability of detecting Salmonella in chick GI tracts. The results of this study suggest potential management decisions to lessen Salmonella contamination of broilers supplied by commercial hatcheries and areas for further research.

Associations between vaccinations against protozoal and viral infections and Salmonella in broiler flocks.

Reducing the burden of Salmonella in broiler flocks presents a challenge for public health. Worldwide, grow-out broilers are routinely vaccinated to prevent or lessen clinical manifestation of other infections. In this exploratory analysis we tested if details of a routine vaccination programme delivered to conventional grow-out broilers were associated with the burden of Salmonella in the flock as it progressed through its production cycle. None of the flocks studied were vaccinated against Salmonella or received a competitive exclusion product. The flocks were reared on conventional grow-out farms in southeastern USA, and sampled in a prospective field observational study. We observed significant associations between the content and design of a grow-out vaccination programme targeting other infections and the probability of detecting Salmonella in the broiler flock at different time points throughout the production cycle. To the best of the authors' knowledge, this is the first field report of such associations.

Risk factors associated with detection of Salmonella in broiler litter at the time of new flock placement.

In this study, we investigated risk factors associated with the probability to detect Salmonella in samples of litter collected within 2 h prior to new flock placement in 76 grow-out houses on 38 conventional broiler farms located in the US states of Mississippi, Alabama and Texas. We evaluated characteristics of location and layout of the farm; area adjacent to and surrounding the house; house construction; condition and type of equipment in the house; litter management and other production, sanitation, visitation and biosecurity practices; non-broiler animal species on the farm; and weather conditions on the 3 days leading up to flock placement. Logistic regression was used to model the relationships between probability to detect Salmonella in litter and potential risk factors. In the screening process, each risk factor was evaluated as a single fixed effects factor in a multilevel model that accounted for variability among the sampled farms and their production complexes and companies. Of almost 370 risk factors screened, 24 were associated with the probability to detect Salmonella in litter. These were characteristics of the surroundings of the house, house construction and conditions, litter management, length of downtimes between flocks in the house, biosecurity and farm location. After investigation of collinearity between these variables and building of models for important risk factor categories, the list of candidate variables for the final model was refined to eight factors. The final model demonstrated that a higher probability of detecting Salmonella in litter was strongly associated with the use of wood to construct the base of the walls or to cover the inside of the broiler house foundation, and with the use of fresh wood shavings to top-dress or completely replace the litter between flocks.

Inter-relationships of Salmonella status of flock and grow-out environment at sequential segments in broiler production and processing.

In this study, we investigated how the likelihoods of Salmonella presence in various samples from broilers and their grow-out environment throughout one production cycle were related. Sixty-four broiler flocks from 10 complexes of two companies in the southern United States were included in the study. Samples from the gastrointestinal tracts of chicks, transport tray pads and litter and drag swabs from the house were collected on the day of placement of each flock. Approximately, 1 week before harvest, whole bird carcass rinses, caecum and crop samples were collected from birds from these same flocks. On the day of harvest, litter and drag swab samples were also taken from the house after the birds were removed. Upon arrival of the flocks at the processing plant, whole carcass rinses, caecum and crop samples were collected. As the flocks were processed, carcass rinses were collected just before the carcasses entered the immersion chill tank and as they exited the chill tank. Logistic regression was used to model the relationships between the likelihood of Salmonella in samples of each type collected at each sampling point and Salmonella frequencies in all the samples taken from the flock and grow-out environment at preceding production stages. The analysis demonstrated that increased likelihood of Salmonella contaminated carcasses entering the immersion chill tank was associated with higher contamination of the exteriors and crops of birds at arrival for processing as well as house environmental samples at the time of harvest and prior to placement. The best predictors of post-chill broiler carcass Salmonella status were the frequencies of Salmonella in the litter on the day of harvest and prior to placement. The immersion chilling appeared to disrupt some of the relationships between the processing plant and pre-harvest samples.

Boron supplementation and activated factor VII in healthy men.

OBJECTIVE: The aim of the present study was to determine whether postprandial concentrations of the active component of serine protease coagulation factor VII (VIIa) were lowered by acute boron supplementation in vivo. DESIGN: An acute, randomized, placebo-controlled, double blind, cross-over study. SETTING: Free-living population. SUBJECTS: Fifteen apparently healthy men, aged 45-65 y. INTERVENTIONS: Subjects visited the centre on two occasions, with the study days separated by a minimum of 2 weeks. Following collection of a fasting blood sample, subjects received either placebo or acute bolus of 11.6 mg boron (given as 102.6 mg sodium tetraborate decahydrate) together with a standard fat-rich meal. Blood samples were obtained at 1, 2, 4 and 6 h after the administration of the test meal, during which time subjects were at liberty to consume deionized water only. Blood samples were assayed for concentrations of insulin, glucose, lipids and boron. Measurement of the concentration of activated factor VIIa and of factor VII antigen, and of the activity of coagulation factors VII, IX and X was also carried out. RESULTS: Plasma boron concentrations were significantly higher following consumption of the boron supplement compared with placebo (0.124+/-0.02 vs 0.008+/-0.01 mg/l; P< or =0.001). There was no significant effect of acute boron supplementation on plasma insulin and glucose concentration or on blood lipid or coagulation factor profile. Factor VIIa rose significantly following consumption of the high fat meal (1.05+/-0.07 vs 1.26+/-0.07; P< or =0.001), but this increase was not altered by boron supplementation. CONCLUSIONS: Results from this study suggest that acute boron supplementation (at 11.6 mg boron) does not alter the activity of factor VIIa following consumption of a high-fat meal. SPONSORSHIP: This work was funded by Borax Europe Ltd.

Comparative toxicology of borates.

Inorganic borates, including boric acid, Na, ammonium, K, and Zn borates generally display low acute toxicity orally, dermally, and by inhalation. They are either not irritant or mild skin and eye irritants. Exceptions owing to physiochemical properties do occur. Longer-term toxicological studies have been reported mainly on boric acid or borax where the properties are generally similar on an equivalent boron (B) basis. The critical effects in several species are male reproductive toxicity and developmental toxicity. The doses that cause these effects are far higher than any levels to which the human population could be exposed. Humans would need to consume daily some 3.3 g of boric acid (or 5.0 g borax) to ingest the same dose level as the lowest animal NOAEL. No effects on fertility were seen in a population of workers exposed to borates or to a population exposed to high environmental borate levels. There is remarkable similarity in the toxicological effects of boric acid and borax across different species. Other inorganic borates that simply dissociate to boric acid are expected to display similar toxicity, whereas those that do not dissociate simply to boric acid may display a different toxicological profile.

Benchmark dose analysis of developmental toxicity in rats exposed to boric acid.

Developmental toxicity risk assessment has typically relied on the estimation of reference doses or reference concentrations based on the use of no-observed-adverse-effect levels (NOAELs) divided by uncertainty factors. The benchmark dose (BMD) approach has been proposed as an alternative basis for reference value calculations. In this analysis of the developmental toxicity observed in rats exposed to boric acid in their diet, BMD analyses have been conducted using two existing studies. By considering various end points (rib XIII effects, variations of the first lumbar rib, and fetal weight changes) and various modeling approaches for those end points, the best approach for incorporating all of the information available from those studies could be determined. Particular emphasis has been placed on methods for combining data across studies and for combining potentially related effects (on rib XIII and on the first lumbar rib). The issues of study and end point selection are ones that will arise frequently in the process of estimating reference values. This example of boric acid suggests that the BMD approach provides a reasonable basis for appropriately comparing and combining study data, as opposed to ad hoc combinations of study results. Moreover, it is shown that the BMD approach can be used with combinations of end points considered to differ in severity. In this case, the preferred approach involved combining the data from the two studies, which were similarly designed and were conducted in the same laboratory, to calculate BMDs that were more accurate and more precise than those that could be derived from either study alone. It was determined that decreased fetal body weight provided the best basis for BMD calculations; BMDs calculated for fetal body weight changes were less than those for all other relevant end points. The appropriate BMD to use as the basis for boric acid reference dose calculation appears to be 59 mg/kg/day, which is very similar to the NOAEL observed in the second of the two studies (55 mg/kg/day). Although the first study failed to establish a NOAEL, the BMD approach could have been applied to that study, thereby avoiding the need for a repeat study. Similar BMD results were obtained in both studies.

Vertebral artery thrombosis due to motor vehicle accident.

Vertebral artery injury is a relatively rare cause of neurologic deficits occurring after blunt trauma. We present the case of a man involved in a motor vehicle accident with resulting vertebral artery injury whose symptoms did not appear until several hours after his initial evaluation in the emergency department. The mechanisms, pathogenesis, presentation, and treatment of these injuries are discussed.

Characterization of S9 fraction used in the third UKEMS collaborative trial.

The S9 preparation utilized by the collaborators in the third UKEMS collaborative study was assayed for the activities of three groups of enzymes and the effect of storage upon the activities. The results obtained indicate that storage of S9 at -196 degrees C for periods of up to 8 months did not unduly affect the activity of the cytochrome P450 isoenzymes measured.

Optical characterization of arsenic-doped silica-on-silicon waveguides using femtosecond optical-time-domain-reflectometry techniques.

Femtosecond OTDR diagnostic techniques are used to investigate the optical properties of arsenic-doped silica-onsilicon waveguides. Results demonstrate that these waveguides have a relatively high refractive index (1.51) and a low loss (<0.5 dB/cm). Owing to the tight optical confinement of the guides, they will have important applications in areas in which high packing densities are required or where direct coupling from semiconductor lasers is needed.

Metabolizing systems in cell culture cytotoxicity tests.

1. The addition of 9000 g supernatant of rat liver homogenate (S9) or rat liver microsomal fractions to a cytotoxicity test system using BCL-D1 cells has been investigated. 2. The choice of culture medium influenced the intrinsic cytotoxicity of the metabolising system to the BCL-D1 cells. Use of Ham's F10 nutrient mixture resulted in greater cytotoxicity compared with several other media. 3. Microsomal fractions provided greater cytochrome P-450 dependent activation of cyclophosphamide and were less cytotoxic than S9. 4. Direct-acting toxic compounds, such as p-aminophenol, were less toxic in the presence of a metabolising system. This was due to protein-binding rather than enzymic detoxification.

A simple and rapid method for the preparation of adenosine triphosphatase from submitochondrial particles.

An almost pure form of the bovine heart mitochondrial adenosine triphosphatase (ATPase) is released from the membrane by shaking submitochondrial particles with chloroform. Analyses on polyacrylamide gels and by electron microscopy, and also sensitivity to inhibitors, show that the chloroform-released enzyme is similar to other ATPase preparations from bovine heart mitochondria.

Cation-exchange separation of uranium in dimethylsulphoxide medium.

Cation-exchange chromatography in a dimethylsulphoxide (DMSO) medium is a suitable means for separating uranium from metal ions, including copper, iron, nickel and molybdenum. Quantitative separations of uranium from 26 elements can best be effected on a column of Dowex 50W-X8 (200-400 mesh), using as the eluent a 20% v/v DMSO solution which is 0.6Min hydrochloric acid and 0.25M in sodium acetate. Only calcium is eluted with the uranium and all other elements studied are eluted either before or after uranium. The elution characteristics of uranium and of other metal ions were investigated with respect to changes in eluent and resin compositions. Separations were much less effective at higher concentrations of sodium ion or DMSO. None of the organic solvents methanol, ethanol, methyl glycol, acetone, dioxan or acetic acid was found to produce favourable separation conditions. Results with Dowex 50 resins of lower or higher cross-linkage were inferior to those obtained with the X8 resin.