Temperature and Density on the Forsterite Liquid-Vapor Phase Boundary.

The physical processes during planet formation span a large range of pressures and temperatures. Giant impacts, such as the one that formed the Moon, achieve peak pressures of 100s of GPa. The peak shock states generate sufficient entropy such that subsequent decompression to low pressures intersects the liquid-vapor phase boundary. The entire shock-and-release thermodynamic path must be calculated accurately in order to predict the post-impact structures of planetary bodies. Forsterite (Mg2SiO4) is a commonly used mineral to represent the mantles of differentiated bodies in hydrocode models of planetary collisions. Here, we performed shock experiments on the Sandia Z Machine to obtain the density and temperature of the liquid branch of the liquid-vapor phase boundary of forsterite. This work is combined with previous work constraining pressure, density, temperature, and entropy of the forsterite principal Hugoniot. We find that the vapor curves in previous forsterite equation of state models used in giant impacts vary substantially from our experimental results, and we compare our results to a recently updated equation of state. We have also found that due to under-predicted entropy production on the principal Hugoniot and elevated temperatures of the liquid vapor phase boundary of these past models, past impact studies may have underestimated vapor production. Furthermore, our results provide experimental support to the idea that giant impacts can transform much of the mantles of rocky planets into supercritical fluids.

Equation of State of CO_{2} Shock Compressed to 1 TPa.

Equation-of-state (pressure, density, temperature, internal energy) and reflectivity measurements on shock-compressed CO_{2} at and above the insulating-to-conducting transition reveal new insight into the chemistry of simple molecular systems in the warm-dense-matter regime. CO_{2} samples were precompressed in diamond-anvil cells to tune the initial densities from 1.35 g/cm^{3} (liquid) to 1.74 g/cm^{3} (solid) at room temperature and were then shock compressed up to 1 TPa and 93 000 K. Variation in initial density was leveraged to infer thermodynamic derivatives including specific heat and Gruneisen coefficient, exposing a complex bonded and moderately ionized state at the most extreme conditions studied.

Erratum: Evidence for a Phase Transition in Silicate Melt at Extreme Pressure and Temperature Conditions [Phys. Rev. Lett. 108, 065701 (2012)].

This corrects the article DOI: 10.1103/PhysRevLett.108.065701.

Evidence for a phase transition in silicate melt at extreme pressure and temperature conditions.

Laser-driven shock compression experiments reveal the presence of a phase transition in MgSiO(3) over the pressure-temperature range 300-400 GPa and 10 000-16 000 K, with a positive Clapeyron slope and a volume change of ∼6.3 (±2.0) percent. The observations are most readily interpreted as an abrupt liquid-liquid transition in a silicate composition representative of terrestrial planetary mantles, implying potentially significant consequences for the thermal-chemical evolution of extrasolar planetary interiors. In addition, the present results extend the Hugoniot equation of state of MgSiO(3) single crystal and glass to 950 GPa.

Varicella infection in pregnancy.

Varicella (chickenpox) is a common childhood illness. Most adults are immune to the virus because of previous exposure. Pregnant women who contract varicella risk complications such as pneumonia. Varicella may be transmitted from mother to fetus and could cause congenital varicella syndrome or perinatal infection. Susceptibility to varicella should be determined before pregnancy. Varicella zoster immune globulin may be considered for the mother or newborn if exposure occurs. Acyclovir may decrease the risk of maternal complications from infection.

Parenting self-efficacy and perception of insufficient breast milk.

OBJECTIVE: Insufficient breast milk is a major reason why mothers give up breastfeeding and may be related to low levels of maternal confidence. This study explored the relationship between parenting self-efficacy (PES) and perception of insufficient breast milk. DESIGN: Cross-sectional descriptive correlational study. SETTING: Four private primary care pediatric practices in the northern United States. PARTICIPANTS: Sixty breastfeeding mothers of infants ages 1 to 11 weeks. PROCEDURES: Mothers were recruited during well-baby pediatric visits. They returned completed questionnaires by mail. Data were analyzed using descriptive statistics, t tests, and multiple regression analysis. MAIN OUTCOME MEASURE: The Perception of Insufficient Milk (PIM) questionnaire, an investigator-developed instrument. RESULTS: There was a significant correlation (r = .487, p < .01) between the self-efficacy and perceived insufficient milk scores. Regression analysis revealed that 23% of the variance in PIM was explained by PES, after maternal age, education, and parity had been taken into account. CONCLUSIONS: Although further research is needed to refine the measurement of perceived insufficient milk and differentiate breastfeeding self-efficacy from general parenting self-efficacy, nursing interventions to enhance self-efficacy may improve mothers' confidence in the adequacy of their milk supply.

Regulation of the catalytic activity of preexisting tyrosinase in black and Caucasian human melanocyte cell cultures.

The activity of tyrosinase, the rate-limiting enzyme for melanin synthesis, is higher in Black skin melanocytes than in melanocytes derived from Caucasian skin. This variation in enzyme activity is not due to differences in tyrosinase abundance or tyrosinase gene activity, but, rather, is due to differences in the catalytic activity of preexisting tyrosinase. In melanocytes, tyrosinase is localized to the membrane of melanosomes and in Caucasian melanocytes the melanosome-bound enzyme is largely inactive. Conversely, in melanosomes of Black melanocytes, tyrosinase has high catalytic activity. Treatment of Caucasian melanocytes with the lysosomotropic compound ammonium chloride or with the ionophores nigericin and monensin results in a rapid and pronounced increase in tyrosinase activity. This increase occurs without any change in tyrosinase abundance, indicating that these compounds are increasing the catalytic activity of preexisting enzyme. Inhibition of the vacuolar proton pump V-ATPase by treatment of Caucasian melanocytes with bafilomycin also increases tyrosinase activity. In contrast to the 10-fold increase in tyrosinase observed in Caucasian melanocytes, neither ammonium chloride, monensin, nigericin, nor bafilomycin is able to increase the already high level of tyrosinase activity present in melanosomes of melanocytes derived from Black skin. Finally, staining of Caucasian melanocytes with the fluorescent weak base acridine orange shows that melanosomes of Caucasian, but not Black, melanocytes are acidic organelles. These data support a model for racial pigmentation that is based on differences in melanosome pH in Black and Caucasian skin types. The models suggests that melanosomes of Caucasian melanocytes are acidic, while those of Black individuals are more neutral. Since tyrosinase is inactive in an acid environment, the enzyme is largely inactive in Caucasian melanosomes but fully active in Black melanosomes.

Downregulation of tyrosinase activity in human melanocyte cell cultures by yohimbine.

Treatment of human melanocyte cell cultures with the alpha-2 adrenergic receptor antagonist yohimbine results in a marked down-regulation of tyrosinase activity. A 30% decrease occurs within 12 h of exposure of cells to yohimbine (100 microM), and by 48 h tyrosinase activity in treated melanocytes is less than a fifth that of control cultures. The inhibition is dose dependent and occurs in human melanocytes derived from either black or white skin types, and also in mouse melanoma cells. The yohimbine-induced decrease in tyrosinase activity is reversible, with enzyme levels returning to 90% of control values 48 h after removal of drug. Although tyrosinase activity is markedly suppressed by yohimbine, the compound has no effect on cell proliferation, cellular translation, or DNA synthesis. Treatment of melanocyte cultures with yohimbine blocks the increase in tyrosinase activity by either 3-isobutyl-1-methylxanthine, dibutyryl cAMP, or forskolin. Results of cAMP immunoassays, show that intracellular levels of the cyclic nucleotide are unaffected in cells treated with yohimbine. Tyrosinase inhibition by yohimbine does not involve a decrease in substrate availability since tyrosine uptake studies show that yohimbine has no effect on the amount of tyrosine entering the cell. Incubation of a melanosome-enriched fraction with yohimbine does not cause a lowering of tyrosinase activity, suggesting that an intact cell is required for yohimbine action. In addition, tyrosinase extracts show no reduction in activity when incubated directly with yohimbine, indicating that the drug does not act as a direct inhibitor of the enzyme. Finally, results of western immunoblotting show that yohimbine does not significantly lower the amount of tyrosinase protein in human melanocytes. These findings suggest that yohimbine acts through an as yet unidentified signaling pathway to lower the catalytic activity of pre-existing tyrosinase molecules present in melanocytes.

Extending storage life of fresh-cut apples using natural products and their derivatives.

Prevention of browning of apples slices has been difficult to achieve because of the rapidity of the enzymatic oxidation of phenolic substrates even under reduced atmospheric pressure storage. Combinations of enzymatic inhibitors, reducing agents, and antimicrobial compounds containing calcium to extend storage life were tested to decrease the browning of Red Delicious apple slices stored at 5 and 10 degrees C under normal atmospheric conditions. Treatments were devised to prevent browning for up to 5 weeks at 5 degrees C with no apparent microbial growth using dipping solutions of compounds derived from natural products consisting of 4-hexylresorcinol, isoascorbic acid, a sulfur-containing amino acid (N-acetylcysteine), and calcium propionate. Analyses of organic acids and the major sugars revealed that the slices treated with the combinations of antibrowning compounds retained higher levels of malic acid and had no deterioration in sugar levels at 5 and 10 degrees C, indicating that higher quality was maintained during storage.

Demonstration of Kaposi's sarcoma-associated herpes virus cyclin D homolog in cutaneous Kaposi's sarcoma by colorimetric in situ hybridization using a catalyzed signal amplification system.

Kaposi's sarcoma-associated herpes virus (KSHV)/human herpes virus 8 (HHV8) DNA sequences have been demonstrated in Kaposi's sarcoma (KS), as well as in some acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphomas (NHL) and in multicentric Castleman's disease. Although KSHV DNA generally is abundant in KSHV-associated lymphomas, few copies of the virus are present in KS, a property that confounds detection by in situ methods. Previous in situ studies, which identified KSHV in lesions of KS, relied on the use of polymerase chain reaction (PCR) to amplify target DNA sequences before in situ hybridization (ISH) for localization or used ISH with radioactively-labeled probes to obtain adequate levels of detection sensitivity. In this study, a novel nonisotopic nucleic acid ISH method using catalyzed signal amplification and colorimetric detection without PCR-dependent target amplification was used to identify KSHV-specific sequences. The level of sensitivity was increased further by using a probe that detects viral cyclin D homolog transcripts, which are expressed at significant levels during latent viral infection. Thirty cutaneous lesions of KS (25 AIDS-related and five classical European type) were evaluated. AIDS-related NHL and cell lines derived from patients with AIDS-related NHL, all of which were known to harbor KSHV by Southern blot analysis, were used as positive controls. NHL and benign cutaneous vascular lesions not associated with AIDS were used as negative controls. For each of the 30 KS lesions studied, hybridization signals were detected in most of the spindle cells surrounding the atypical slit-like vascular channels and also were detected in some endothelial cells in well-formed blood vessels in the perilesional dermis. Plaque and nodular lesions generally contained more labeled cells than did early patch lesions. All AIDS-related NHL and cell lines contained KSHV-specific sequences; however, the non-AIDS-related NHLs and benign vascular lesions were negative. These results confirm the presence of KSHV sequences in cutaneous KS and provide in situ evidence of infection by this virus in early patch-stage lesions. This study also defines the in situ expression of the KSHV cyclin D homolog viral oncogene in cutaneous KS. The use of this sensitive nonisotopic ISH method should allow detection of other KSHV-specific gene products, further defining the pathobiology of this virus.

S phase determination in intact colonic crypts by histone H3 messenger RNA in situ hybridization and confocal microscopy.

Proliferating cells have a restricted three-dimensional spatial distribution within the crypt, which is the proliferative unit of the colon. Accurate quantitative and spatial analyses of S phase cells in the colon have therefore been limited by histological techniques. To overcome these limitations, S phase cells in microdissected intact colonic crypts of control, modified-starved, and refed rats were labeled by histone H3 in situ hybridization and analyzed by confocal microscopy. High-resolution digital images of the crypt cell nuclei stained with cyanine nucleic acid and of the labeled S phase cells were produced from confocal microscopic optical crypt sections. The S phase labeling index (LI) per whole crypt significantly (P < 0.001) discriminated the proliferative differences between control, modified-starved, and refed rats and correlated (r = 0.92) with the LI determined from histological crypt sections of the same rats. The variance component of the LI attributable to differences between whole crypts, 0.44 (95% confidence interval, 0.38-0.51), was considerably smaller than that attributable to differences between histological crypt sections, 6.07 (95% confidence interval, 5.18-6.96). Confocal microscopy and histone H3 in situ hybridization of intact three-dimensional crypts enables precise in vitro quantitation and spatial analysis of the total and S phase crypt cells.

Accuracy of histone H3 messenger RNA in situ hybridization for the assessment of cell proliferation in human tissues.

Histone H3 mRNA in situ hybridization was compared to a reference method, iododeoxyuridine (IdUrd) immunohistochemistry of tissues labeled in vivo, as a means for assessing the proportion of S-phase cells (labeling index, LI) in oral tumor and normal mucosa. Paraffin sections from 16 patients with oral squamous cell carcinoma were studied. Patients received an IdUrd infusion before the biopsy was taken. Tissue sections were coded before counting the percentages of S-phase cells. A high correlation was found between the results obtained by the two techniques. The average histone H3 and IdUrd LIs of the tumors were 28.5 +/- 2.4% and 29.2 +/- 2.7%, respectively (P = 0.85), with a Spearman correlation coefficient r = 0.95 (P < 0. 0001). The histone H3 LI of the basal layer of normal mucosa was 3.1 +/- 0.8%, whereas the IdUrd LI was 2.7 +/- 0.9% (P = 0.74), with r = 0.78 (P = 0.004). In the suprabasal layers, these parameters were 21. 3 +/- 2.3% and 23.9 +/- 3.2%, respectively (P = 0.56), with r = 0.93 (P < 0.0001). In sections stained for both histone H3 and IdUrd, most cells were double labeled, with very few cells containing only one of the labels. In some specimens, large areas of H3-stained cells did not contain IdUrd-labeled cells, suggesting that during the IdUrd infusion, the precursor did not reach these areas. Two specimens were histone H3 negative. They were also negative when hybridized with beta-actin probe, indicating degradation of mRNAs in these samples. The results of this study demonstrate that the histone H3 mRNA in situ hybridization performed in human formalin-fixed, paraffin-embedded tissues provides the same data as does labeling the tumors in vivo with halogenated pyrimidine.

Validation of the S-phase specificity of histone (H3) in situ hybridization in normal and malignant cells.

Several different methods of measuring proliferation indices have been developed, including measurements of cellular DNA content (flow cytometry), S-phase incorporation of thymidine analogues into DNA (e.g., tritiated thymidine and 5'-bromodeoxyuridine), and immunostaining of cell cycle-restricted proteins (e.g., Ki-67 antigen and PCNA). Theoretical and practical problems with each method have made it difficult to compare absolute proliferation rates among cells of different lineages and degrees of malignancy. More recently, in situ hybridization (ISH) for histone 3 (H3) mRNA has been introduced. We used a double labeling method for comparing H3 mRNA expression and S-phase incorporation of 5'-bromodeoxyuridine (BrdU) to determine if H3 mRNA expression was tightly associated with S-phase in a variety of malignant and nontransformed cell types. In addition, labeling results were compared in methacarn- and formalin-fixed tissues to extend the potential usefulness of H3 ISH, using a postfixation technique for the alcohol-fixed specimens. As expected for a cumulative marker, variation was noted in the percentage of the BrdU-positive cells double labeled with H3 ISH (53-89%), depending on cell type and length of BrdU incubation. In contrast, the percentage of the H3 ISH-positive cell population double labeled for BrdU was independent of the cell type of BrdU incubation time (mean 78%). Similarly, a consistent percentage of H3 ISH-positive cell populations was double labeled for BrdU in normal tissues (mean 97%). These findings support a well-conserved timing mechanism for H3 mRNA expression and DNA replication. We conclude that H3 ISH is an extremely accurate technique for assessment of S-phase cell proliferation indices.

Histone H3 messenger RNA in situ hybridization correlates with in vivo bromodeoxyuridine labeling of S-phase cells in rat colonic epithelium.

Measurements of cell cycle phase fractions, particularly S-phase, are useful for studies of cell biology and carcinogenesis. Up-regulation of histone gene expression is tightly coupled to the G1-S-phase transition of the cell cycle, and mRNA levels rise 30-100-fold during S-phase. Labeling of histone H3 mRNA using in situ hybridization (ISH) was assessed as a measure of S-phase cells and compared with that found using in vivo 5-bromodeoxyuridine (BrdUrd) labeling in formalin-fixed rat colonic crypts under baseline, modified 72-h starvation, and 24-h refeeding conditions. The labeling index scored in single-labeled sections by histone H3 ISH tightly correlated with that found by in vivo BrdUrd labeling (r = 0.99, p < 0.0001) and clearly discriminated between the control, starved, and refed states (P < 0.001). In 180 crypt sections double labeled using histone H3 ISH and BrdUrd, 92% of 1572 labeled cells exhibited both nuclear BrdUrd and cytoplasmic histone H3 label. It is concluded that histone H3 ISH is an accurate measure of the S-phase fraction and provides an alternative to in vivo BrdUrd labeling in rat colon. This finding warrants validation in human studies.

Multiple HPV infection: microanatomy by in situ hybridization and immunohistochemistry.

Specific human papillomavirus (HPV) types have been shown to be associated with proliferative epithelial lesions with variable biological consequences in infected patients. Simultaneous infection by more than one HPV type has been infrequently reported, and its clinical significance is unknown. We have examined four biopsies of cervical and vulvar tissue, each with evidence of infection by two different HPVs. Using both in situ hybridization and immunohistochemical techniques, we determined the cellular distribution of the viral infections. Using biotinylated type-specific probes and stringent conditions we were able to demonstrate that in each case the two HPVs occupied distinct, non-overlapping foci within the lesions. The condylomatous tissues contained DNA from HPV types that are associated with high-grade neoplasia and invasive cancer (16 and 18), as well as types commonly associated with benign proliferative lesions. Immunohistochemical analysis of the lesions with antibody to bovine papillomavirus capsid antigen failed to detect HPV in regions shown by in situ hybridization to contain HPV 16 and 18 DNA, whereas type 6 and 11 infected areas were readily identified. These results provide indirect evidence of viral interference between HPV types and indicate that interference may limit the number of HPV types that produce active infections within a single cell.

Evaluation of a DNA probe of plasmid origin for the detection of Chlamydia trachomatis in cultures and clinical specimens.

This study evaluates five cryptic plasmid-derived DNA probes in a 4-h slot-blot hybridization assay for the detection of Chlamydia trachomatis in cultures and clinical specimens. The probes, consisting of either the entire cloned 7.5 kbp cryptic plasmid pSE8 or one of four Hin dIII/Eco RI fragments measuring 710, 1055, 710, and 500 bp, respectively, were labelled with Photoprobe biotin. The probe was detected using a streptavidin-alkaline phosphatase conjugate followed by addition of BCIP and NBT. The sensitivity of the assay, using 25 ng of probe DNA, ranged from 50 pg (with the entire plasmid as probe) to 5 ng (with the 500 bp fragment as probe). A total of 103 reference strains of Chlamydia trachomatis and other bacteria were tested for reactivity with the probes. All 18 reference strains of C. trachomatis hybridized with the probes. None of the DNA from the heterologous organisms tested was found to hybridize with any of the probes. A total of 174 samples taken from patients visiting the STD clinic at the University Hospital, University of Seville were used in the study. The overall sensitivity of the assay, using the 710 bp biotinylated probe was 94.5% compared to culture while the specificity was 97.5%. Positive and negative predictive values were 96.5% and 97.5%, respectively. It appears that the plasmid-derived probes used in this study could serve as useful tools for the rapid and specific detection of Chlamydia trachomatis in cell cultures and clinical specimens.

Purification and characterization of sulfatases from Haliotis rufescens: evidence for changes in synthesis and heterogeneity during development.

The digestive glands of many marine molluscs are rich sources of arylsulfatase enzymes which may function in the catabolism of sulfated polysaccharides in the diets of herbivorous species. Arylsulfatases, partially purified from the hepatopancreas of the red abalone, Haliotis rufescens, were investigated with respect to heterogeneity, catalytic requirements, and timing of induction during development. Four hepatopancreatic enzymes were purified from adult animals using a combination of hydrophobic interaction and anion-exchange chromatography. Zymograms of the four partially-purified enzymes produced by electrophoresis under nondenaturing conditions revealed a fifth, relatively more basic isozyme. All four partially-purified enzymes appear to be monomeric, with molecular weights of approximately 43,000 Da each, as measured by gel filtration. The affinities for p-nitrocatechol sulfate, pH optima, and strengths of inhibition by anions displayed by these enzymes are similar to the values reported for other molluscan arylsulfatases. Three of the four enzymes have Km values between 0.8 and 2.0 mM for p-nitrocatechol sulfate; the remaining enzyme (A2) has a Km of 6.7 mM. All four enzymes have pH and temperature optima of 5.5 and 45 degrees C, respectively. Three of the four enzymes have-t 1/2 (50 degrees C) values of 3.5 min; the enzyme A4 has a t 1/2 (50 degrees C) of 8.5 min. A monoclonal antibody directed against form A1b does not cross react with any of the other hepatopancreatic arylsulfatases when assayed by Western blot, confirming the structural heterogeneity of the adult enzymes. Total arylsulfatase activity increases in a biphasic manner during early abalone development, with the first increase occurring early in larval maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen inhibition of globin gene transcription and bacterial haemoglobin synthesis in Vitreoscilla.

A soluble dimeric haemoprotein, structurally and functionally similar to plant and animal haemoglobins, is found in the Gram-negative aerobic bacterium Vitreoscilla sp., strain C1. Vitreoscilla haemoglobin (VtHb) increases in concentration when the cells are exposed to hypoxic conditions. The globin part of VtHb is encoded by a single gene (vgb). An RNA transcript, approximately 500 bases long, specific for vgb was detected after Northern hybridization. The relative amount of this mRNA increased in cells grown at low levels of oxygen. Two enzymes important for haemoglobin function are delta-aminolaevulinic acid synthase (ALAS), which is necessary for haem biosynthesis, and NADH-methaemoglobin reductase, which is necessary to keep VtHb in the physiologically functional ferrous state. An increase in ALAS specific activity under hypoxic conditions preceded the increased haem production. Cellular reductase content also increased when the VtHb increased in cells grown under hypoxic conditions. The ratio of cellular reductase activity to VtHb content remained relatively constant in cells grown under a variety of conditions. The data suggest that in Vitreoscilla the transcription of the globin gene and the biosynthesis of two enzymes important for VtHb function are regulated by oxygen.

Allelochemicals in tall fescue-abscisic and phenolic acids.

Growth inhibitors that can be leached from excised leaves of tall fescue grass (Festuca arundinacea) were investigated as allelochemicals. Leachates of desiccated Rebel and Kentucky 31 grass cultivars contained three principal inhibitory compounds, abscisic acid (ABA), caffeic acid, andp-coumaric acid. After quantitative analysis, abscisic acid was determined to be the predominant inhibitor. A 10-fold increase in ABA levels in leachates occurred after one day of desiccation. The concentration of ABA was 40% greater in Kentucky 31 leachate than in Rebel. This difference was also found in subsequent analyses of leachates of grasses that had been allowed to dry up to 30 days; however, the ABA concentration was reduced by 60% from the 10-fold increased levels.