Saturated Saline Research Articles

Virus–host interactions in environments with a wide range of ionic strengths

Although high-salt environments are rich in viruses, virus-host interactions have not been much explored. Here we study the virus-host interactions occurring in a variety of salt environments, up to saturated salinity. We chose viruses from different environments with diverse morphologies that included both bacterial and archaeal viruses. To extend the test virus set five new haloviruses were isolated and initially characterized in this study. We observed adsorption rates that varied over four orders of magnitude among the virus-host cell systems used in this study. Changes in ionic strength affected the adsorption of these viruses to their host cells in a variety of ways. All the studied viruses, regardless from which environment they were isolated, were more resistant to variations in ionic strength conditions than their host cells. Our study provides a glimpse of the early events in virus life cycles for a number of viruses from different environments. We also gained information on viral responses to changing environments, a valuable piece of information in extending our understanding of the viruses in the environment.

Effect of salting processes on chemical composition, textural properties and microstructure of duck egg

AbstractBACKGROUND: Salted eggs have been produced in Thailand and consumed nationwide. Salted egg can be made by brining eggs in saturated saline or by coating the egg with soil paste mixed with salt. The achievement of salting is generally indicated by the textural development of egg yolk. Yolk property is therefore a prime factor governing consumer acceptability and market demand. The objective of this study was to determine chemical composition, textural properties and microstructure of duck egg obtained from the coating and immersing methods at different salting times.RESULTS: Decreases in moisture content with coincidental increases in salt content in both egg white and yolk were observed during salting, regardless of salting process. However, no difference in salt content was noticeable in yolks (P > 0.05). The paste coating method tended to yield greater oil exudation of egg yolk than the immersing method. Maximum transition temperature (Tmax) of egg proteins and thiobarbituric acid‐reactive substance (TBARS) value in yolk increased with increasing salting time. A similar hardening ratio of yolk was observed in both processes. Higher hardness and adhesiveness were found in yolk with the paste coating method, whereas greater fracturability, springiness, gumminess and chewiness were observed with the immersing method. Nevertheless, both processes rendered the yolk with similar cohesiveness. Yolk granules were aligned closely when salting proceeded, irrespective of salting process.CONCLUSION: Dehydration and release of lipids in egg yolk increased with increasing salting time and were more pronounced with the paste coating method. Therefore salting processes affected the properties of salted eggs. Copyright © 2009 Society of Chemical Industry

Neuroprotective effects of hydrogen saline in neonatal hypoxia–ischemia rat model

Cerebral hypoxia–ischemia (HI) represents a major cause of brain damage in the term newborn. This study aimed to examine the short and long-term neuroprotective effect of hydrogen saline (H 2 saline) using an established neonatal HI rat pup model. Seven-day-old rat pups were subjected to left common carotid artery ligation and then 90 min hypoxia (8% oxygen at 37 °C). H 2 saturated saline was administered by peritoneal injection (5 ml/kg) immediately and again at 8 h after HI insult. At 24 h after HI, the pups were decapitated and brain morphological injury was assessed by 2,3,5-triphenyltetrazolium chloride (TTC), Nissl, and TUNEL staining. Acute cell death, inflammation and oxidative stress were evaluated at 24 h by studying caspase-3 activity, MDA measurement as well as Iba-1 immunochemistry in the brain. At 5 weeks after HI, spontaneous activity test and Morris water maze test were conducted. We observed that H 2 saline treatment reduced the caspase activity, MDA, Iba-1 levels, the infarct ratio, and improved the long-term neurological and neurobehavioral functions. H 2 saline has potentials in the clinical treatment of HI and other ischemia-related cerebral diseases.

Cloud point extraction and spectrophotometric determination of Cu(II) in saturated saline solutions using 4-ethyl-1-(pyridin-2-yl)thiosemicarbazide

4-Ethyl-1-(pyridin-2-yl)thiosemicarbazide (HEPTS) has been used as a new complexing agent in cloud point extraction (CPE) for preconcentration and determination of trace amounts of copper in saturated saline medium. The chemical variables affecting the separation and determination processes were optimized. Copper(II) is preconcentrated using 0.05% (w/v) Triton X-114 and 10−4 M HEPTS at pH 6. The surfactant rich phase containing the complex was dissolved in 2 mL MeOH and determined spectrophotometrically. The calibration curve is linear in the 0.1–25 ng/mL copper range. The proposed method was applied successfully in the determination of copper in water and saturated saline samples. The reaction between CuSO4 and HEPTS yields a deep-blue solid complex which is characterized by analytical and spectroscopic analyses.

Potassium Lactate Combined with Sodium Diacetate Can Inhibit Growth of Listeria monocytogenes in Vacuum-Packed Cold-Smoked Salmon and Has No Adverse Sensory Effects

Growth of Listeria monocytogenes in ready-to-eat fish products such as cold-smoked salmon is an important food safety issue. The objective of this study was to evaluate the antilisterial activity of potassium lactate (PL) in combination with sodium acetate (SA) or sodium diacetate (SDA) in cold-smoked salmon and to determine whether these compounds could be incorporated easily into the formulations and technology currently used by processors. A commercial brine injector was used to inject salmon filets with either saturated saline brine or saturated saline brine supplemented with combinations of PL and SA (PURASAL Opti.Form PA 4) or PL and SDA (PURASAL Opti.Form PD 4). In the brine-injected cold-smoked salmon, 2.1% (water phase) PL and 0.12% (water phase) SDA delayed the growth of L. monocytogenes for up to 42 days of vacuum-packaged storage at 10°C. Storage at 25°C for 6 h resulted in only a 1-log CFU/g increase in L. monocytogenes. Treatments with lower concentrations of PL and SDA or similar concentrations of PL and SA resulted in an extended lag phase and slower growth of L. monocytogenes. It was not possible to incorporate more than 2% (water phase) PL while ensuring a minimum of 3% (water phase) NaCl in the finished product because PL decreased the solubility of NaCl. Sensory analyses revealed that the preservatives did not negatively affect flavor or odor. The combination of PL and SDA is therefore a viable technology for preventing L. monocytogenes growth on cold-smoked salmon.

Chemical Tumor Ablation with Use of a Novel Multiple-tine Infusion System in a Canine Sarcoma Model

To determine whether larger confluent zones of ablation can be achieved in chemical ablation with use of a multiple-tine infusion device compared with standard needle infusion in a solid tumor model. Multiple canine venereal sarcomas (N=42) were implanted in nine mildly immunosuppressed dogs (treated with 10 mg/kg cyclosporin A twice daily). Tumors incubated for 8-12 weeks grew to a diameter of 5.4 cm+/-1.0. With ultrasound guidance, 8-56 mL of 100% ethanol or 15% acetic acid (diluted in saturated saline solution) were injected in aliquots (2-8 mL) at multiple distances (radius of 0-2 cm) from the needle axis with use of a multiple-tine infusion device. Presence of fluid reflux at the needle puncture site and resultant coagulation diameters were measured within 1 hour and compared with the results of infusion with a standard 18-gauge needle. Multiple-tine infusion enabled greater fluid infusion (15 mL+/-3 to 53 mL+/-3 depending on protocol) than standard needle injection (8 mL+/-1) before reflux was observed at the puncture site (P<.01). Additionally, progressive gains in contiguous tumor coagulation were achieved because acetic acid was infused as far as 2 cm from the needle axis with the multiple-tine device (P<.01; R(2)=0.59; y=0.5x+2.9). Optimal coagulation was achieved with the infusion of 4-mL aliquots at 0.5 cm and 1.0 cm from the needle, followed by three 4-mL or 8-mL aliquots (40 degrees rotation between infusions) at 1.5 cm and 2.0 cm from the needle (32 mL+/-0 and 53 mL+/-3 total, respectively). This yielded confluent short-axis coagulation diameters of 4.9 cm+/-1.0 and 5.4 cm+/-1.0, respectively, which were significantly greater than the measurement of 3.1 cm+/-0.4 achieved with standard needle infusion (P<.01). Smaller and noncontiguous foci of coagulation foci (1.7 cm+- 0.5) were seen with the use of ethanol for standard needle and multiple-tine infusions. Chemical ablation with 15% acetic acid with use of a multiple-tine infusion device resulted in larger diameters of contiguous tumor coagulation and enabled greater volumes of infusion than standard needle infusion or ethanol ablation. This suggests that chemical ablation with acetic acid infused with use of a multiple-tine device may overcome some of the difficulties seen with the use of conventional needle chemical ablation injection alone, such as irregular ablation and fluid reflux up the needle tract.

Controlling suction by the vapour equilibrium technique at different temperatures and its application in determining the water retention properties of MX80 clay

Problems related to unsaturated soils are frequently encountered in geotechnical or environmental engineering works. In most cases, for simplicity, one can study the problems by considering the suction effects on volume change or shear strength under isothermal conditions. Often, under these conditions, a temperature-independent water retention curve is considered in the analysis — obviously a simplification. When the temperature changes are too significant to be ignored, it is necessary to account for the thermal effects. This note presents a method for controlling suction with the vapour equilibrium technique at different temperatures. First, calibration of various saturated saline solutions was carried out at temperatures ranging from 20 °C to 60 °C. A mirror psychrometer was used to measure relative humidity generated by saturated saline solutions at different temperatures. The results obtained were in good agreement with the data from the literature. This information was then used to determine the water retention properties of MX80 clay, which showed that the retention curve shifts downward with increasing temperature.Key words: vapour equilibrium technique, hygrometer, water retention curve, temperature effects, compacted bentonite.

Tongue scrapping as a means of reducing oral mutans streptococci

Mutans streptococci (MS) are one of the most virulent cariogenic pathogens in the oral cavity. The effects of three oral hygiene techniques on salivary mutans streptococci levels were evaluated to see which mechanism would be most efficient in reducing salivary MS levels. Sixty patients, all in the permanent dentition, were selected and randomly distributed into three groups. Group I was asked to use a tongue scraper to brush the tongue once daily in the morning after normal tooth brushing routine. Group II was asked to place and let dissolve a Listerine Oral Care Strip on the tongue once daily after normal oral hygiene routine. Group III was asked to rinse once every morning, for thirty seconds, with a saturated saline solution after routine tooth brushing. The instructions were done for a period of seven days. Baseline, one hour, three day, and seven day saliva samples were obtained and plated on CRT" by Vivadent MS-sensitive agar. All treatments groups show a significant reduction in colony counts from baseline and one or more post treatment periods and at one or more time periods between treatment groups. The most effective treatment in reducing colony counts was seen within Group I "Tongue Scraping" which demonstrated the greatest change from baseline to each of the post treatment periods. The least effective was Group II "Listerine Strip" which showed a statistically insignificant increase in colony count from baseline to 1-Hour and a significant decrease from baseline at the 7-day period only.

기름담금 염장발효 굴의 가공을 위한 최적 염장발효조건

우리나라 전통수산발효식품 중의 하나인 굴 젓갈을 소재로 하여 장기간 상온저장이 가능하며, 생굴의 풍미를 지닌 기름담금 염장발효 굴 제품을 가공하기 위한 최적 염장발효 조건과 염장발효 중의 성분변화에 대하여 살펴보았다. 염장 발효 중 식염의 침투는 염장 초기에 완료되었으며, 아미노질 소량은 저온숙성 20일째까지 계속 증가하다가 이후 일정한 함량을 유지하였고, 굴 자숙농축액을 첨가한 시료가 아미노질 소의 함량이 가장 많았다. 염장발효 굴의 경도는 숙성 10일째 까지 증가하다가 그 이후는 육 조직의 일부가 가수분해됨에 따라 점차 육질이 연화되어 감소하는 경향을 보였다. 염장 직후의 생균수는 무염배지 및 2.5% 가염배지에서 각각 1.0~1.1×10² CFU/g, 6.7×10² CFU/g이었고, 저온숙성 중 무염배지에서는 생균수가 전반적으로 변화를 보이지 않았으나, 2.5% 가염배지에서는 숙성 15일째까지 생균수가 뚜렷이 증가하다가 이후 감소하는 경향을 보였다. 염장발효 굴은 맛과 냄새 및 종합적 기호도 면에서 저온숙성 15~20일째에 가장 좋았으며, 굴 자숙농축액을 첨가하여 염장발효시킨 시료가 특히 맛과 향기 면에서 우수하였다. 이상의 결과를 종합하여 볼 때, 기름담금 염장발효 굴 제품을 가공하기 위한 최적 염장발효 조건은 탈각한 생굴을 3% 식염수로서 수세하여 물 빼기를 한 다음, 포화식염수와 굴 자숙농축액의 2 : 1 혼합용액에 대해 1% sodium erythorbate와 0.2% polyphosphate를 각각 첨가한 염장액으로 물간하여 5±1℃에서 15일간 발효 숙성시키는 것이 가장 좋았다.

Human fasciolosis in Van province, Turkey

This investigation was carried out to determine the frequency of the fasciolosis in Erciş, a town in the Van province located in the Eastern Turkey. The study includes 500 asymptomatic subjects (322 males and 178 females) whose ages ranged from 5 to 75 years. In all subjects, stool samples were examined at initiation of the study and one week later to rule out pseudoparasitosis. The methods of flotation (in saturated saline solution) and sedimentation (in formalin–ether solution) were used in examination of the stool samples. Fasciola hepatica eggs were detected in nine (1.8%) out of 500 subjects. In conclusion, our data showed that the prevalence of human fasciolosis was high in our region because watercress consumption was common. We also think that human fasciolosis is more frequent than expected in Turkey. To determine the exact prevalence of the disease, extensive serological investigations should be performed in different regions of Turkey.

Groundwater Exploration With Aem in the Boteti Area, Botswana

AEM data acquired with the TEMPEST system in the Boteti area, Botswana, were used to map lithologies and structures for potential fresh groundwater. The survey area is characterised by the Makgadikgadi paleolake system bordered by elevated terrain to the south. Lower-lying areas are characterised by a thick layer of Kalahari Beds with saline groundwater generally situated less than 20 m below surface. Elevated areas are generally characterised by Karoo sediments, consisting of sandstones and mudstones, at shallow depths.Within the paleolacustrine terrain, target aquifers are freshwater zones associated with recharge pans above a saline water table. The correlation of AEM-derived conductivity-depth profiles with borehole records shows that the conductivity of Kalahari Beds is primarily a function of clay content, water saturation, and water salinity. The shallow conductivity structure from modelled AEM data outlines several resistive zones, some of them located within Boteti River alluvium beneath the present and past river channels.In the elevated terrain, target aquifers are sandstones lying between dry alluvium or basalt, and mudstone. Basalts are characterised by very low conductivities and a strong magnetic response. The underlying sandstones and mudstones have low and high conductivities, respectively, and are offset by horst and graben structures, which are mapped in both the magnetic data and conductivity-depth sections. Resistivity iso-surfaces generated from the 3D conductivity data facilitate the spatial appreciation of the geometry of modelled structures. Favourable locations for freshwater exploitation interpreted from TEMPEST data include faults, dykes, a paleochannel incised into mudstone, and shallow fractured sandstone especially when overlain by basalt.

Synthesis and characterization of block comb‐like copolymers P(A‐MPEO)‐block‐PSt

AbstractAmphiphilic block comb‐shaped copolymers, poly[poly(ethylene oxide) methyl ether acrylate]‐block‐polystyrene [P(A‐MPEO)‐block‐PSt] with PSt as a handle, were successfully synthesized via a macromonomer technique. The reaction of MPEO with acryloyl chloride yielded a macromonomer, A‐MPEO. The macroinitiator PSt capped with the dithiobenzoate group (PSt‐SC(S)Ph) was prepared by reversible addition–fragmentation transfer (RAFT) polymerization of styrene in the presence of benzyl dithiobenzoate, and used as macroinitiator in the controlled radical block copolymerization of A‐MPEO at room temperature under 60Co irradiation. After the unreacted macromonomer A‐MPEO had been removed by washing with hot saturated saline water, block comb‐shaped copolymers were obtained. Their structure was characterized by 1H NMR spectroscopy and gel permeation chromatography. The phase transition and self‐assembling behaviour were investigated by atomic force microscope and differential scanning calorimetry. Copyright © 2004 Society of Chemical Industry

Effects Of Hydrogen Peroxide, Cold Storage And Descapsulation On The Hatching Success Of Artemia Cysts

The effects of hydrogen peroxide, cold storage and decapsulation on diapause in partheno- genetic Artemia cysts from the Izmir Çamalti saltern were tested. To test the effect of hydrogen peroxide, cyst samples were incubated for 5 min in a 2% or 5% H2O2 solution. In the cold stor- age experiments, the cysts were divided into three groups. One group was stored in saturated saline, the second in a vacuum and the third in air for 15 days or one month. Decapsulation was tested after a 2-hour prehydration period. The hatching rate of the control group after 24 h in cysts harvested in November was 0, while in cysts harvested in March it was 19.2%. All the treatments for diapause deactivation resulted in increased hatching during the first 24 h but the final hatch- ing rates (at 72 h) of all treated groups were similar to or slightly lower than that of the control.

Diarrhea and acaroid mites: a clinical study.

To explore the characteristics of diarrhea caused by acaroid mites. Acaroid mites in fresh stools of 241 patients with diarrhea were separated by flotation in saturated saline. Meanwhile, skin prick test, total IgE and mite-specific IgE were detected in all patients. The total positive rate of mites in stool samples of the patients was 17.01 % (41/241), the positive rates of mites in male and female patients were 15.86 % (23/145) and 18.75 % (18/96), respectively, without significant difference (P>0.05). The percentage of skin prick test as "+++", "++", "+", "+/-" and "-" was 9.13 % (22/241), 7.47 % (18/241), 5.81 % (14/241), 4.98 % (12/241) and 72.61 % (175/241), respectively. The serum levels of total IgE, mite-specific IgE in patients with and without mites in stool samples were (165.72+/-78.55) IU/ml, (132.44+/-26.80) IU/ml and (145.22+/-82.47) IU/ml, (67.35+/-45.28) IU/ml, respectively, with significant difference (P<0.01). The positive rate of mites in stool samples in staffs working in traditional Chinese medicine storehouses or rice storehouses (experimental group) was 26.74 % (23/86), which was significantly higher than that (11.61 %, 18/155) in people engaged in other professions (chi(2)=8.97, P<0.01). Acaroid mites cause diarrhea and increase serum levels of total IgE and mite-specific IgE of patients, and the prevalence of diarrhea caused by acaroid mites is associated with occupations rather than the gender of patients.

Acaroid mite, intestinal and urinary acariasis.

To investigate epidemiology and pathogenic mite species of intestinal and urinary acariasis in individuals with different occupations. A total of 1994 individuals were tested in this study. History collection, skin prick test and pathogen identification were conducted. The mites were isolated from stool and urine samples by saturated saline flotation methods and sieving following centrifugation, respectively. Among the 1994 individuals examined, responses to the skin prick test of "+++", "++", "+","+/-" and "-" were observed at frequencies of 3.96 % (79), 3.21 % (64), 2.31 % (46), 1.25 % (25) and 89.27 % (1780), respectively. A total number of 161 (8.07 %) individuals were shown to carry mites, with 92 (4.61 %) positive only for stool samples, 37 (1.86 %) positive only for urine samples and 32 (1.60 %) for both. The positive rate of mites in stool samples was 6.22 % (124/1994), being 6.84 % (78/1140) for males and 5.39 % (46/854) for females. No gender difference was observed in this study (chi(2)=1.77, P>0.05). The mites from stool samples included Acarus siro, TyroPhagus putrescentiae, Dermatophagoides farinae, D. pteronyssinus, Glycyphagus domesticus, G. ornatus, Carpoglyphus lactis and Tarsonemus granaries. The positive rate of mites in urine samples was 3.46 % (69/1994). The positive rates for male and female subjects were found to be 3.95 % (45/1140) and 2.81 % (24/854) respectively, with no gender difference observed (chi(2)=1.89, P>0.05). Mites species in urine samples included Acarus siro, Tyrophagus putrescentiae, T. longior, Aleuroglyphus ovatus, Caloglyphus berlesei, C. mycophagus, Suidasia nesbitti, Lardoglyphus konoi, Glycyphagus domesticus, Carpoglyphus lactis, Lepidoglyphus destructor, Dermatophagoides farinae, D. pteronyssinus, Euroglyphus magnei, Caloglyphus hughesi, Tarsonemus granarus and T. hominis. The species of mites in stool and urine samples were consistent with those separated from working environment. A significant difference was found among the frequencies of mite infection in individuals with different occupations (chi(2)=82.55, P<0.001), with its frequencies in those working in medicinal herb storehouses, those in rice storehouse or mills, miners, railway workers, pupils and teachers being 15.89 % (68/428), 12.96 % (53/409), 3.28 % (18/549), 2.54 % (6/236), 5.10 % (13/255) and 2.56 % (3/117), respectively. The prevalence of human intestinal and urinary acariasis was not associated with gender, and these diseases are more frequently found in individuals working in medicinal herb, rice storehouses or mills and other sites with high density of mites. More attention should be paid to the mite prevention and labor protection for these high-risk groups.

Serological response to Cryptosporidium parvum in adult cattle from the Andean region of Colombia.

Single faecal and serum samples were individually collected from 135 asymptomatic adult cows on seven farms in Cundinamarca (Colombian Andean region). Tests for the presence of oocysts of Cryptosporidium parvum (carbol fuchsin stain) and Eimeria spp (flotation in saturated saline solution) revealed that none of the animals had coccidia in their faeces. The IgG antibody levels to C. parvum were measured by an enzyme-linked immunosorbent assay (ELISA) technique and the reactivity to C. parvum antigens by a Western blotting procedure. Cryptosporidial antibodies were detected in cattle from all farms, with 53.3% (72 animals) being seropositive. Sera recognized 5-11 protein fractions with molecular masses ranging from 12 14 kDa to 97-100 kDa. Sera considered as positive by ELISA reacted intensely and more frequently with protein fractions of approximately 20-22, 42-48, 51-57 and 60-69 kDa, whereas only the 42-48 kDa antigen was strongly recognized by sera without IgG antibodies. The presence of IgG antibody against C. parvum in most animals, as well as the reactivity to major proteins of C. parvum, could be indicative of continuous exposure to this parasite.

Electrode Impedance in Neurophysiologic Recordings: 3. Effects on Recorded Signals

ABSTRACT.EEG and evoked potential (EP) recordings depend on the properties of the electrodes used. The current set of experiments explores the effects of electrode properties on signal recordings in the absence of intrinsic noise or electromagnetic interference (EMI). The entire electrode-amplifier unit can be considered as a single electronic device with its own characteristic frequency response, which is more complex than that expected simply on the basis of setting the high- and low-frequency filters on the amplifier itself. These experiments demonstrate that the response of platinum-iridium pin electrodes and gold cup electrodes is decreased by roughly 50% for 1 Hz signals when compared to their responses at 100 Hz. Sensitivity increases again for a narrow band of frequencies below 1 Hz. This effect is most dramatic for stainless steel hookwire electrodes, which demonstrate much higher sensitivity to signals in the .1–1 Hz waveband than in the 1–1000 Hz waveband, although their sensitivity increases above 1000 Hz. Although similar responses are seen with electrodes placed in physiologic saline and embedded in a potato, dramatically different responses are recorded when the same electrodes are placed in a saturated saline solution. Changing electrode impedances can have complex and substantial effects on the frequency-dependent gain of the electrode-amplifier unit as well.

Determination of trace uranyl in saline samples using chelation ion chromatography

A liquid chromatographic method for the determination of trace levels of UO22+ in highly saline samples has been developed. A polystyrene divinylbenzene reversed-phase column was impregnated with methylthymol blue, resulting in a chelating stationary phase. An isocratic method, using a 0.5 M KNO3, 40 mM HNO3 eluent, allowed the direct injection of up to 0.2 ml of a saline sample, with UO22+ eluting away from the sample matrix peak in under six minutes. The development of an eluent step gradient procedure, using a step up from 6 mM HNO3 to 60 mM HNO3, allowed sample injection volumes of up to 2 ml without substantial peak broadening and resulted in a detection limit for UO22+ of less than 1 µg l–1, in samples containing massive excesses of matrix metals. The procedure was applied to the determination of trace UO22+ in a saturated saline Antarctic lake sample. The results obtained compared well with those obtained using ICP-MS.

Nitric oxide inhibits aromatase activity: mechanisms of action.

NO synthase is present in human ovarian granulosa-luteal cells and NO inhibits estradiol secretion by granulosa cells in culture. These findings suggest that NO is an autocrine regulator of ovarian steroidogenesis. The purpose of this investigation was to explore the mechanisms through which NO exerts an inhibitory effect on cytochrome P450 aromatase activity. To examine the effect of NO on aromatase mRNA levels, human granulosa-luteal cells were cultured in the presence or absence of the NO donor SNAP for 16 h. Using a probe for human aromatase, Northern blots revealed a 26% decrease in aromatase mRNA in cells exposed to SNAP. Because this modest decrease in mRNA is unlikely to explain a rapid and profound reduction in estradiol secretion that we have observed, we looked for direct effects of NO on cytochrome P450 aromatase activity. Aromatase activity was assayed in placental microsomes and granulosa-luteal cells by measuring the release of 3H2O from [1 beta-3H] androstenedione. NO (10(-4)-10(-3)M), added as a saturated saline solution, reduced aromatase activity by as much as 90% in a concentration-dependent, non-competitive manner. In contrast, carbon monoxide (CO), a gas known to bind to the heme iron in aromatase, had no effect on aromatase activity when added alone nor could CO reverse the NO-induced inhibition of aromatase. These data suggest that NO binding to the heme is insufficient to inhibit aromatase activity. NO has been reported to alter protein function by reacting with the sulfhydryl group of cysteines, forming a nitrosothiol group. Because a cysteine sulfhydryl group is thought to participate in the catalytic mechanism of all P450 enzymes, experiments were designed to test whether NO might inhibit aromatase via such a mechanism. Addition of increasing amounts of mercaptoethanol, a chemical with free sulfhydryl groups, blocked the NO-induced inhibition of aromatase in microsomes. N-Ethylmaleimide, a chemical which covalently modifies sulfhydryl groups, reduced aromatase activity in a concentration-dependent manner. We conclude that NO inhibits aromatase both by decreasing mRNA for the enzyme and by an acute, direct inhibition of enzyme activity. We hypothesize that the direct inhibition occurs as a result of the formation of a nitrosothiol on the cysteine residue adjacent to the heme in aromatase.

Fluid variability in 2 GPa eclogites as an indicator of fluid behavior during subduction

Fluid activity ratios calculated between millimeter- to centimeter-scale layers in banded mafic eclogites from the Tauern Window, Austria, indicate that variations in aH2O existed between layers during equilibration at P approximately equal to 2GPa and T approximately equal to 625°C, whereas aCO2 was nearly constant between the same layers. Model calculations in the system H2O−CO2−NaCl show that these results are consistent with the existence of different saturated saline brines, carbonic fluids, or immiscible pairs of both in different layers. The data cannot be explained by the exisience of water-rich fluids in all layers. The model fluid compositions agree with fluid inclusion compositions from eclogite-stage veins and segregations that contain (1) saline brines (up to 39 equivalent wt. % NaCl) with up to six silicate, oxide, and carbonate daughter phases, and (2) carbonic fluids. The formation of crystalline segregations from fluid-filled pockets or hydrofractures indicates high fluid pressures at 2 GPa; the record of fluid variability in the banded eclogite host rocks, however, implies that fluid transport was limited to local flow along individual layers and that there was no large-scale mixing of fluids during devolatilization at depths of 60–70 km. The lack of evidence for fluid mixing may, in part, reflect variations in wetting behavior of fluids of different composition; nonwetting fluids (water-rich or carbonic) would be confined to intergranular pore spaces and would be essentially immobile, whereas wetting fluids (saline brines) could migrate more easily along an interconnected fluid network. The heterogeneous distribution of chemically distinct fluids may influence chemical transport processes during subduction by affecting mineral-fluid element partitioning and by altering the migration properties of the fluid phase(s) in the downgoing slab.