Evaluating structure-based activity in a high-throughput assay for steroid biosynthesis.

Data from a high-throughput human adrenocortical carcinoma assay (HT-H295R) for steroid hormone biosynthesis are available for >2000 chemicals in single concentration and 654 chemicals in multi-concentration (mc). Previously, a metric describing the effect size of a chemical on the biosynthesis of 11 hormones was derived using mc data referred to as the maximum mean Mahalanobis distance (maxmMd). However, mc HT-H295R assay data remain unavailable for many chemicals. This work leverages existing HT-H295R assay data by constructing structure-activity relationships to make predictions for data-poor chemicals, including: (1) identification of individual structural descriptors, known as ToxPrint chemotypes, associated with increased odds of affecting estrogen or androgen synthesis; (2) a random forest (RF) classifier using physicochemical property descriptors to predict HT-H295R maxmMd binary (positive or negative) outcomes; and, (3) a local approach to predict maxmMd binary outcomes using nearest neighbors (NNs) based on two types of chemical fingerprints (chemotype or Morgan). Individual chemotypes demonstrated high specificity (85-98%) for modulators of estrogen and androgen synthesis but with low sensitivity. The best RF model for maxmMd classification included 13 predicted physicochemical descriptors, yielding a balanced accuracy (BA) of 71% with only modest improvement when hundreds of structural features were added. The best two NN models for binary maxmMd prediction demonstrated BAs of 85 and 81% using chemotype and Morgan fingerprints, respectively. Using an external test set of 6302 chemicals (lacking HT-H295R data), 1241 were identified as putative estrogen and androgen modulators. Combined results across the three classification models (global RF model and two local NN models) predict that 1033 of the 6302 chemicals would be more likely to affect HT-H295R bioactivity. Together, these in silico approaches can efficiently prioritize thousands of untested chemicals for screening to further evaluate their effects on steroid biosynthesis.

An improved method for examining fat taste.

PURPOSE: The detection of fat taste in humans requires the delivery of hydrophobic stimuli to the oral cavity. Due to their low solubility in water, these fat taste stimuli are difficult to administer to test subjects by means of aqueous solutions or dispersions. These hydrophobic stimuli are also difficult to prepare in sufficient amounts to generate an appreciable chemosensory response. METHODS: An improved procedure for preparing thin edible strips that contain 18-carbon fatty acids as representative fat taste stimuli is described. This protocol includes the addition of low amounts of the dispersing agent xanthan gum and high drying temperature during film formation. These edible strips can be prepared in 4-5 h, are highly flexible, and evenly disperse long-chain fatty acids at micromole amounts. Due to the rapid dissolving time of these strips in the oral cavity, this delivery method generates minimal tactile responses. RESULTS: Psychophysical studies with edible strips indicate that nearly all individuals detected linoleic acid, with intensity responses in the weak to moderate range. Fewer individuals perceived stearic acid, with most intensity responses in the barely detectable range. Both fatty acids caused a fatty/oily or bitter taste response in the majority of test subjects. Finally, these intensity responses allowed the development of edible circles for regional testing of the tongue. CONCLUSION: This novel delivery method for hydrophobic stimuli should be useful for examining human fat taste perception, characterizing variations in fat taste perception, and identifying the emerging role of fat taste in human health.

Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares.

Sgr A*, the supermassive black hole (SMBH) at the center of our Milky Way Galaxy, is known to be a variable source of X-ray, near-infrared (NIR), and submillimeter radiation and therefore a prime candidate to study the electromagnetic radiation generated by mass accretion flow onto a black hole and/or a related jet. Disentangling the power source and emission mechanisms of this variability is a central challenge to our understanding of accretion flows around SMBHs. Simultaneous multiwavelength observations of the flux variations and their time correlations can play an important role in obtaining a better understanding of possible emission mechanisms and their origin. This paper presents observations of two flares that both apparently violate the previously established patterns in the relative timing of submillimeter/NIR/X-ray flares from Sgr A*. One of these events provides the first evidence of coeval structure between NIR and submillimeter flux increases, while the second event is the first example of the sequence of submillimeter/X-ray/NIR flux increases all occurring within ~1 hr. Each of these two events appears to upend assumptions that have been the basis of some analytic models of flaring in Sgr A*. However, it cannot be ruled out that these events, even though unusual, were just coincidental. These observations demonstrate that we do not fully understand the origin of the multiwavelength variability of Sgr A* and show that there is a continued and important need for long-term, coordinated, and precise multiwavelength observations of Sgr A* to characterize the full range of variability behavior.

Simultaneous X-Ray and Infrared Observations of Sagittarius A*'s Variability.

Emission from Saggitarius A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ~20 yr have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A* is observed to be continuously variable. Recently, simultaneous observations have indicated a rise in IR flux density around the same time as every distinct X-ray flare, while the opposite is not always true (peaks in the IR emission may not be coincident with an X-ray flare). Characterizing the behavior of these simultaneous X-ray/IR events and measuring any time lag between them can constrain models of Sgr A*'s accretion flow and the flare emission mechanism. Using 100+ hours of data from a coordinated campaign between the Spitzer Space Telescope and the Chandra X-ray Observatory, we present results of the longest simultaneous IR and X-ray observations of Sgr A* taken to date. The cross-correlation between the IR and X-ray light curves in this unprecedented data set, which includes four modest X-ray/IR flares, indicates that flaring in the X-ray may lead the IR by approximately 10-20 min with 68% confidence. However, the 99.7% confidence interval on the time-lag also includes zero, i.e., the flaring remains statistically consistent with simultaneity. Long-duration and simultaneous multi-wavelength observations of additional bright flares will improve our ability to constrain the flare timing characteristics and emission mechanisms, and must be a priority for Galactic Center observing campaigns.

Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole.

Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the most comprehensive NIR variability data set of Sgr A* to date: eight 24 hr epochs of continuous monitoring of Sgr A* at 4.5 µm with the IRAC instrument on the Spitzer Space Telescope, 93 epochs of 2.18 µm data from Naos Conica at the Very Large Telescope, and 30 epochs of 2.12 µm data from the NIRC2 camera at the Keck Observatory, in total 94,929 measurements. A new approximate Bayesian computation method for fitting the first-order structure function extracts information beyond current fast Fourier transformation (FFT) methods of power spectral density (PSD) estimation. With a combined fit of the data of all three observatories, the characteristic coherence timescale of Sgr A* is τ b = 243 - 57 + 82 minutes (90% credible interval). The PSD has no detectable features on timescales down to 8.5 minutes (95% credible level), which is the ISCO orbital frequency for a dimensionless spin parameter a = 0.92. One light curve measured simultaneously at 2.12 and 4.5 µm during a low flux-density phase gave a spectral index α s = 1.6 ± 0.1 ( F ν ∝ ν - α s ) . This value implies that the Sgr A* NIR color becomes bluer during higher flux-density phases. The probability densities of flux densities of the combined data sets are best fit by log-normal distributions. Based on these distributions, the Sgr A* spectral energy distribution is consistent with synchrotron radiation from a non-thermal electron population from below 20 GHz through the NIR.

Dissecting x-ray-emitting gas around the center of our galaxy.

Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy's SMBH provides an instructive exception, and we present a close-up view of its quiescent x-ray emission based on 3 megaseconds of Chandra observations. Although the x-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission on the basis of the lack of predicted iron (Fe) Kα emission. The extremely weak hydrogen (H)-like Fe Kα line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.

Production responses following strategic parasite control in a beef cow/calf herd.

Strategic parasite control has been reported to improve performance in a beef cow/calf herd that does not demonstrate clinical parasitism. This study was conducted to determine if strategic anthelmintic treatment at turnout and at midsummer would improve growth and reproduction. Two cow/calf groups of similar composition were grazed on separate, but equivalent pastures in the spring, and at midsummer, they were moved to new pastures. The treated group was given fenbendazole at tumout (cows) and at midsummer (cows and calves). The control group was not treated. The study was repeated in the following year. Across both years of the study, parasite egg counts were substantially reduced in both the treated cows (P < 0.005) and treated calves (P < 0.0001). The calves in the treated group significantly (P < 0.0001) outgained the control calves in both years of the study by 19.3 kg and 13.2 kg, respectively. Average daily gain (ADG) after adjusting for birth weight and birth date for treated calves was 0.13 kg greater than for control calves (0.83 vs 0.70) for the 2-year study (P < 0.0001) There was also a significant (P = 0.0357) increase in the reproductive performance of the cows. The pregnancy rate averaged across years was 94% for the treated cows compared to 82% for the control animals.

Epizootiology of helminth parasitism in a beef cow/calf herd in Minnesota.

To test the effect of a parasite control program for cattle, 2 groups of similar composition were grazed on separate, but equivalent, improved pastures. Cattle in 1 group were treated with fenbendazole at 5.0 mg/kg of body weight at the time they were turned out on pasture in the spring and again at midsummer, when the cattle were moved to a new pasture. The control group was not treated. Parasite egg counts were significantly (P less than 0.04) lower in the treated group. Trichostrongyle-type eggs were the most prevalent throughout the year, except in the month of May, when Strongyloides papillosus eggs were predominant. The number of worms recovered from tracer calves was lower for those on pastures where the treated group grazed than for those on the control group's pasture. The most consistently recovered parasite was Ostertagia ostertagi, and hypobiosis was observed.

Detection of bovine leukemia virus in cattle by the polymerase chain reaction.

Bovine leukemia virus (BLV) is widely distributed in U.S. cattle herds. It infects B lymphocytes and causes neoplastic disease in 5-10% of infected animals. Direct economic losses are incurred as a result of death, reduced milk production and condemnation at slaughter. Thus the identification of cattle infected with BLV is of significant concern to the U.S. cattle industry. For this reason, polymerase chain reaction (PCR) amplification was used to examine seropositive and seronegative cattle for the presence of BLV DNA in peripheral blood mononuclear cells. Using an amplification protocol able to detect 1 viral genome in 100,000 cells, BLV was not detected in 7 seronegative cattle in an infected herd. BLV sequences were detected in 13 of 18 seropositive animals with various levels of infection as determined by in vitro lymphocyte culture and electron microscopy. An active infection was demonstrated in one animal, based on the presence of viral RNA. These findings indicate that PCR is a sensitive method for the detection of BLV in cattle and provides new information regarding the dynamics of the infection.

Maternal-child interaction in survivors of severe malnutrition who received psychosocial stimulation.

Jamaican children who had recovered from severe malnutrition 3 years previously (CM group) were observed with their mothers in a structured play situation. Their behaviour was compared with two other groups; another severely malnourished group which had participated in an intervention programme of psychosocial stimulation (IM group) and an adequately nourished group (controls). All children were subjects in a longitudinal intervention study (Grantham-McGregor, Schofield & Powell, 1987). Both malnourished groups had very low levels of development (DQ) initially. The CM group's DQs remained low but the IM group caught up to the controls. During the observation the CM children stayed nearer their mothers and played less than the children in other groups. It was hypothesized that this behaviour could have contributed to their poor development. The IM children behaved similarly to the controls. It is probable that non-nutritional intervention had changed their behaviour. Only little differences were found between the mothers.

Failure to demonstrate transmission of enzootic bovine leukemia virus infection from cows to sheep by use of common injection needles.

Four bovine leukemia virus (BLV)-seropositive and 2 BLV-seronegative cows were used as donors in a study to provide evidence whether IM injection with common needles is a means of spreading bovine leukemia. Sheep were used as recipients. Of the 4 BLV-seropositive cows, 2 had high virus expression (VE; 43% and 28% of their lymphocyte thin sections had associated BLV-particles), whereas the other 2 cows did not have observed VE. After each of the 4 cows was given an injection of a 5-antigen Leptospira bacterin, a BLV-seronegative sheep was immediately given an injection of the same bacterin with the same needle. None of these sheep seroconverted, nor did either of 2 sheep given only the bacterin (with a previously unused needle). Sheep inoculated IM with 0.2 ml of whole blood from both of the cows with high VE and from 1 of the 2 BLV-seropositive cows that did not have observed VE did seroconvert. In contrast, the sheep inoculated with 0.2 ml of blood from the remaining BLV-seropositive (0% VE) cow and from the 2 BLV-seronegative cows remained seronegative. These results were interpreted to indicate that the quantity of infective lymphocytes passed during injection with common needles is too small to induce infection.

In vitro viral expression as a criterion for development of control procedures for enzootic bovine leukosis.

In a university beef herd of 304 cattle in which six died of lymphosarcoma between 1980 and 1984, 77% of the Angus and 26% of the Charolais cattle were determined to be infected with bovine leukemia virus (BLV). Changes in iatrogenic procedures were initiated as early control measures. In vitro viral expression (VE) was used as a criterion to identify cattle for subsequent segregation or culling. This involved determinations of percentages of BLV-associated lymphocyte profiles among thin-sectioned Ficoll-Paque-isolated blood lymphocytes that were processed into plastic after culture for 48 h. Cattle retained until completion of nutritional studies or as breeding stock were separated into two groups. The BLV-seronegative cattle, BLV-seropositive cattle with 0% VE, and BLV-seropositive cattle with 1% to 4% VE were placed in group 1. Seropositive cattle with greater than or equal to 5% VE were placed in group 2. In 1985, evaluation of in vitro VE in 108 mature BLV-seropositive cattle retained for breeding revealed 36 (33%) had no observable VE. In 1986, 58 of 108 cattle were available to be reexamined, and 21 (36%) had 0% VE in both years. The VE expression values for individual cattle were generally comparable over the 2-year period. Of 48 initial seronegative breeding stock housed in group 1 with BLV-seropositive cattle with low or no VE, 21 (44%) seroconverted during 1985 to 1986. A positive correlation of 0.585 was found between VE and age-related absolute lymphocyte number.

Deposition and early disposition of inhaled 233UO2(NO3)2 and 232UO2(NO3)2 in the rat.

Little information exists on the metabolism and potential health effects of 233U and 232U, high-specific-activity U isotopes associated with Th breeder systems. This paper describes the distribution and retention of the two isotopes following inhalation of uranyl nitrate, a simulated process solution. The lungs of rats exposed to 233UO2(NO3)2 and 232UO2(NO3)2 aerosols contained from 7 to 23% of the total amount of U retained in the rat after a 30-min inhalation exposure. Uranium was translocated rapidly from the lung and was retained mainly in skeleton, kidney and liver. Amounts equivalent to from one-quarter to one-half the initial lung burden (ILB) of U were excreted in urine the first day after inhalation. Radiation dose estimates based on 233U and 232U retention kinetics indicate that lung and skeleton would be the target organs for delayed radiation effects.

Bovine enteric colibacillosis.

In this article, the authors discusses procedures used to determine enteropathogenic strains of Escherichia coli, the history of the development of prophylactic procedures, including cow vaccination and specific monoclonal antibody, and other preventative measures with as proper management, nutrition, and sanitation.

Iodine toxicosis in six herds of dairy cattle.

Daily iodine intake estimated to range from greater than 68 to 600 mg/animal/day was associated with signs referable to iodine intoxication in adult cows in 6 herds of dairy cattle. Signs were reversed by lowering supplemental intake to less than 12 mg/animal/day. Results of biochemical tests other than those for serum and milk iodine were not diagnostic. Serum iodine concentrations were 2.6 to 6.9 times the mean iodine concentration found in 12 control cows, each receiving 12 mg of iodine/day. Milk iodine concentrations were 3.6 to 13.6 times milk iodine concentrations in the control cows.

Exposure to the unconditioned stimulus alone: effects on retention and acquisition of conditioned suppression.

Three experiments demonstrated that repeated exposure to an electric-shock unconditioned stimulus (US) resulted in a decrement in retention of conditioned suppression evoked by a previously established excitatory conditioned stimulus (CS) and retarded subsequent acquisition of conditioned suppression to a novel CS paired with shock. Experiment 1 showed that 10 sessions of exposure to shock alone were required to produce a decrement in retention of conditioned suppression, whereas retardation in the acquisition of conditioned suppression was obtained following either 5 or 10 sessions of exposure to shock alone. Experiment 2 demonstrated that the magnitude of both the decrement in retention of conditioned suppression and the retardation in the acquisition of conditioned suppression produced by exposure to shock alone was directly related to the intensity of those shocks. Experiment 3 demonstrated that the decrement in retention of conditioned suppression produced by 10 sessions of exposure to shock alone was inversely related to the interval between the last exposure to shock and the test of the target CS. These findings are discussed in terms of associative and nonassociative accounts of the effects of US-alone procedures.

Subclinical mastitis of beef cows.

Two beef cow herds were investigated to determine the prevalence of subclinical mastitis and to determine whether it contributed to decreased weaning weight of calves nursed by affected cows. Quarter samples obtained about 30 days after calving were evaluated by the California mastitis test and by direct microscopic cell count. In 1 herd, a 92-cow confinement operation, 17 quarters of 12 cows were infected with Staphylococcus aureus, Streptococcus sp other than agalactiae, or Klebsiella sp. Mean 205-day adjusted weights were 203.9 kg and 218.2 kg for calves nursed by infected vs noninfected cows. In the other herd, a 75-cow range-pasture operation, 8 quarters of 8 cows were infected, all with S aureus. Mean 205-day adjusted weights were 162.5 kg and 174.6 kg for calves nursed by infected vs noninfected cows.