A randomized, controlled trial examining quarter-level somatic cell count and culture-based selective dry cow therapy against blanket dry cow therapy on early-lactation production outcomes.

The objective of this study was to determine quarters requiring antimicrobial treatment using either a benchtop somatic cell counter (S-SDCT) or culture with gram-positive selective media (C-SDCT) and compare outcomes in these cows to those receiving blanket dry cow therapy (BDCT) in a randomized, controlled trial. Two novel methods of identifying cows with intramammary infections followed by selective antimicrobial treatment were evaluated at a commercial dairy farm to determine their usefulness in decreasing antibiotic usage during the dry period without significant detrimental effects on milk quality and production. Cows (n = 840) were randomly allocated to one of 3 groups (BDCT, C-SDCT, S-SDCT) the day before dry-off and quarter-level milk samples (QLMS) were collected. The QLMS from cows in the S-SDCT group were evaluated using the cell counter and quarters were treated if somatic cell count (SCC) was ≥200,000 cells/mL, while QLMS from cows in the C-SDCT group were cultured and quarters were treated if the culture showed growth. All cows in the BDCT received antimicrobial therapy and all cows received an internal teat sealant regardless of treatment group. Outcomes measured were first and second DHIA test somatic cell count, milk production through 60 d in milk, cows leaving the farm, clinical mastitis, and bacteriologic new infections in a subset of quarters. Cows in both SDCT groups had fewer antimicrobial treatments than cows in the BDCT group as was expected, and cows in the C-SDCT group had fewer treatments than those in the S-SDCT group. Cows in both SDCT groups had higher linear score at the first DHIA test (BDCT: 1.8, S-SDCT: 2.2, C-SDCT: 2.2), however there were no other differences between groups regarding any other outcomes measured. While antimicrobial use was significantly reduced, farms should use caution in adopting the benchtop analyzer and the selective media described in this study as ways to identify infected cows for dry cow therapy as they may result in increased linear score early in lactation.

Comparison of an image cytometry somatic cell count analyzer to a flow cytometry analyzer.

The objective of this study was to evaluate the performance of a small footprint benchtop somatic cell counter based on image cytometry (LactiCyte HD; Page and Pedersen International Ltd., Hopkinton, MA) against a flow cytometer employed at a regional dairy herd improvement (DHI) laboratory. Milk samples collected during monthly DHI testing were split into 2 samples. One sample was evaluated using flow cytometry (Bentley SomaCount FCM; Bentley Instruments, Chaska, MN) at the regional DHI laboratory, whereas the other was evaluated using image cytometry at 2 different image levels (full number of images, 16 pictures per slide; half number of images, 8 pictures per slide). Mean bias of the image cytometer at 16 images was -15,500 cells/mL, whereas at 8 images the bias was 21,800 cells/mL. When considering only cell counts ≤400,000 cells per mL, the bias for both imaging resolutions was positive, meaning the image cytometer read higher than the flow cytometer. Both imaging resolutions (16 and 8) had a concordance correlation coefficient greater than 0.95. Considering ≥200,000 cells/mL to be indicative of subclinical mammary gland infection, the sensitivity and specificity of the image cytometer at 16 images were 92.0% and 91.7%, whereas the sensitivity and specificity of the analyzer at 8 images were 92.0% and 85.7%, respectively. Method precision (repeatability; coefficients of variation) were calculated at 3 different somatic cell counts (100,000, 200,000, and 400,000 cells/mL) where each sample was run repeatedly 12 times. When analyzed at the full number of images the coefficients of variation were 16.9%, 11.7%, and 10.9% for 100,000, 200,000, and 400,000 cells/mL, respectively. Analysis at half the number of images resulted in coefficients of variation of 18.9%, 24.8%, and 8.7% for 100,000, 200,000, and 400,000 cells/mL. We conclude that the image cytometer is an acceptable somatic cell count analyzer for on-farm use for applications such as screening cows for microbiological testing, and that precision is superior when the analysis is performed at the full number of images allowed by the instrument.

MAD analysis of FHIT, a putative human tumor suppressor from the HIT protein family.

BACKGROUND: The fragile histidine triad (FHIT) protein is a member of the large and ubiquitous histidine triad (HIT) family of proteins. It is expressed from a gene located at a fragile site on human chromosome 3, which is commonly disrupted in association with certain cancers. On the basis of the genetic evidence, it has been postulated that the FHIT protein may function as a tumor suppressor, implying a role for the FHIT protein in carcinogenesis. The FHIT protein has dinucleoside polyphosphate hydrolase activity in vitro, thus suggesting that its role in vivo may involve the hydrolysis of a phosphoanhydride bond. The structural analysis of FHIT will identify critical residues involved in substrate binding and catalysis, and will provide insights into the in vivo function of HIT proteins. RESULTS: The three-dimensional crystal structures of free and nucleoside complexed FHIT have been determined from multiwavelength anomalous diffraction (MAD) data, and they represent some of the first successful structures to be measured with undulator radiation at the Advanced Photon Source. The structures of FHIT reveal that this protein exists as an intimate homodimer, which is based on a core structure observed previously in another human HIT homolog, protein kinase C interacting protein (PKCI), but has distinctive elaborations at both the N and C termini. Conserved residues within the HIT family, which are involved in the interactions of the proteins with nucleoside and phosphate groups, appear to be relevant for the catalytic activity of this protein. CONCLUSIONS: The structure of FHIT, a divergent HIT protein family member, in complex with a nucleotide analog suggests a metal-independent catalytic mechanism for the HIT family of proteins. A structural comparison of FHIT with PKCI and galactose-1-phosphate uridylyltransferase (GaIT) reveals additional implications for the structural and functional evolution of the ubiquitous HIT family of proteins.

Transabdominal chorionic villus sampling at 9.5-12 weeks' gestation. Placental vascular resistance and fetal cardiovascular responses.

Pregnancies subjected to chorionic villus sampling (CVS) have been associated with transverse limb reduction defects. This study was designed to examine the possible fetal cardiovascular responses to transabdominal CVS. We examined 42 patients referred for CVS between 9.5 and 12 weeks' gestation. CVS was performed transabdominally under ultrasonic guidance with a 20-gauge needle. Placental vascular resistance was evaluated by means of the umbilical artery pulsatility index. Fetal heart rate was ascertained automatically from two successive flow velocity waveforms. Paired t test, regression analysis, power analysis and normal distribution analysis were performed, and statistical significance was set at P < or = .05. Fetal heart rate increased with increasing amounts of tissue, but placental vascular resistance did not change. The earlier the gestation, the larger the amount of tissue obtained. Multiple regression analysis demonstrated that the fetal heart rate change was influenced by neither gestation nor placental vascular resistance after CVS. Analysis of the change (difference before and after CVS) in placental resistance and fetal heart rate according to gestational age and amount of tissue did not change the above findings. Although statistically significant fetal cardiovascular responses can be elicited in relation to the amount of chorionic villi obtained during transabdominal CVS, the clinical significance of these findings remains unclear, given the fact that all the fetuses in this group of patients were normal. These responses may be secondary to various degrees of placental hemorrhage and may represent part of or the total fetal response to various degrees of fetal blood loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Kinetics of the lamellar-inverse hexagonal phase transition determined by time-resolved X-ray diffraction.

The kinetics of the lamellar (L alpha)-inverse hexagonal (HII) phase transition in diacylphosphatidylethanolamine (PE)--water systems were probed with time-resolved X-ray diffraction. Transition kinetics in the fast time regime (approximately 100 ms) were studied by initiating large temperature jumps (up to 30 degrees C) with a 50-ms electrical current pulse passed through a lipid-salt water dispersion, resulting in ohmic heating of the sample. Diffraction with a time resolution to 10 ms was acquired at the National Synchrotron Light Source. The time constant for the phase transition for 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) was on the order of 100 ms for the largest temperature jumps recorded. Faster transition behavior was found for a 1,2-dielaidoyl-sn-glycero-3-PE mixture. The HII lattice parameters for both systems were seen to swell from an initial value commensurate with the lamellar lattice to the final equilibrium value. The rate of swelling was seen to be independent of the magnitude of the temperature jump. For small temperature jumps (less than 10 degrees C), the phase transition kinetics slow dramatically, and transition studies can readily be performed on a conventional rotating anode X-ray source. At 4 degrees C, a DOPE sample was observed to slowly convert to the hexagonal phase over the course of a week, with the decay in the lamellar intensity fitting a power law behavior over four decades of time. This power law behavior is shown to have interesting consequences to the determination of the phase transition temperature of lipid-water dispersions by conventional methods such as calorimetry.

Three-Dimensional X-ray Microtomography.

The new technique of x-ray microtomography nondestructively generates three-dimensional maps of the x-ray attenuation coefficient inside small samples with approximately 1 percent accuracy and with resolution approaching 1 micrometer. Spatially resolved elemental maps can be produced with synchrotron x-ray sources by scanning samples at energies just above and below characteristic atomic absorption edges. The system consists of a high-resolution imaging x-ray detector and high-speed algorithms for tomographic image reconstruction. The design and operation of the microtomography device are described, and tomographic images that illustrate its performance with both synchrotron and laboratory x-ray sources are presented.

Evaluation of image processing and presentation methods in thallium-201 myocardial scintigraphy.

Using a phantom to simulate the LAO 45 degrees thallium-201 myocardial image with a transmural infarct of variable detectability, thirteen methods of computer image processing are evaluated for a group of eight observers using receiver operating characteristics (ROC curves). Initial results using electrostatic hardcopy images clearly demonstrate that images with three applications of a nine point smoothing routine and 30% background subtraction, displayed with three cycles of the grey scale, produce significantly more accurate interpretation (P less than 0.001) than the raw data, or any of the other methods used. This method provides an overall increase in the diagnostic sensitivity for the group and does not introduce a false positive bias. Grey scale cycling provides effective contrast enhancement as does a colour scale presentation. Comparing images as processed above with similarly smoothed images presented with a fifteen colour level scale on a TV monitor, the diagnostic sensitivities are not significantly different and this method provides the optimum image evaluation in this study.