Expression of ABC transporter and scavenger receptor mRNAs in PBMCs in 100-km ultramarathon runners.

BACKGROUND: Cholesterol metabolism is tightly regulated at the cellular level. This study was to measure the expression levels of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1), scavenger receptor class B type I (SR-BI) and class A (SRA), and CD36 mRNAs in peripheral blood mononuclear cells (PBMCs) in response to 100-km ultramarathon event and determine any correlation between these ABC transporters/scavenger receptor expression levels and plasma cholesterol homeostasis. MATERIALS AND METHODS: Twenty-six participants were enrolled. Blood was drawn from each individual 1 week prior, immediately after, and 24 hours after the race. The expression levels of ABCA1, ABCG1, SR-BI, SRA and CD36 in PBMCs were measured by using real-time quantitative reverse transcription polymerase chain reaction. RESULTS: Plasma triglyceride levels were significantly increased immediately after the race and dropped at 24-hour post-race compared with pre-race values. The 100-km ultramarathon boosted high-density lipoprotein cholesterol (HDL-C) levels and decreased low-density lipoprotein cholesterol (LDL-C) levels 24-hour post-race. The expression levels of ABCA1, ABCG1 and SR-BI were markedly decreased, whereas that of CD36 was slightly but significantly upregulated in runners' PBMCs immediately after the race. Ultramarathon resulted in immediate large-scale stimulation of inflammatory cytokines with increased plasma interleukin-6 and tumour necrosis factor-alpha levels. Moreover, by using in vitro models with human monocytic cell lines, incubation of runners' plasma immediately after the race significantly downregulated ABCA1 and ABCG1, and upregulated CD36 expression in these cells. CONCLUSIONS: ABCA1, ABCG1 and CD36 gene expressions in PBMCS might be associated with endurance exercise-induced plasma cholesterol homeostasis and systemic inflammatory response.

Electrical Cardiometry and Cardiac Biomarkers in 24-h and 48-h Ultramarathoners.

Our study aimed to (i) utilize novel electrical cardiometry and observe acute changes in cardiac biomarkers among 24-h and 48-h ultra-marathoners, and (ii) examine whether alterations in cardiac responses were associated with the average running speed of these participants. Twenty-four 24-h and sixteen 48-h ultra-marathoners were recruited. Electrical cardiometry in the 2 groups showed significant post-race drops in systolic pressure (24-h: p=0.001; 48-h: p=0.016) and rapid increases in heart rate (24-h, p=0.004; 48-h, p=0.001). Cardiac output increased in 48-h runners (p=0.012) and stroke volume decreased in 24-h runners (p=0.009) at post-test. Six of 20 (30%) 24-h and 4 of 16 (25%) 48-h runners had high-sensitivity troponin T values above the reference interval after the races. N-terminal proB-type natriuretic peptide levels showed a 15-fold increase in 24-h runners and a 10-fold increase in 48-h runners at post-race. There was a positive correlation between delta N-terminal proB-type natriuretic peptide and running mileage (rs=0.629, p=0.003) in 24-h ultra-marathoners. In conclusion, stroke volume and cardiac output showed inconsistent changes between the 2 groups. Average running speed has a significant effect on post-exercise elevation in cardiac biomarkers.

Effects of 100-km ultramarathon on erythropoietin variation in runners with hepatitis B virus carrier.

Completing an ultramarathon leads to an immediate postrace surge of erythropoietin (EPO). Patients with chronic liver disease may have high plasma EPO concentrations. This study aims to explore whether plasma EPO concentrations vary between hepatitis B virus carrier (HBVc) and non-HBVc runners during long distance running. Blood samples were collected from 8 HBVc and 18 non-HBVc runners at 3 different time points: 1 week before, immediately following, and then 24 h after the 100-km ultramarathon race. Samples were analyzed for plasma EPO levels. EPO concentration had a statistically significant rise immediately after the race (8.7 [7.1-11.9] mU·mL-1 to 23.7 [14.8-37.2] mU·mL-1, P < 0.001) and maintained the high levels 24 h after the race finished (16.7 [11.5-21.0] mU·mL-1, P < 0.001) in all participants. The mean of EPO concentration was 8.9 (5.7-13.2) mU·mL-1 in HBVc runners and was 8.7 (7.7-11.2) mU·mL-1 in non-HBVc runners in the prerace. In HBVc runners, plasma EPO levels were no different at baseline (P = 0.657) and increased in the same fashion in response to ultramarathon compared with non-HBVc runners. Plasma EPO levels between the two groups were not statistically different at any time point. Prolonged endurance exercise led to a significant increase in EPO. A comparable increase in EPO levels was observed in HBVc and non-HBVc runners during and 24 h after 100-km ultramarathon. However, a small sample size might have affected the ability to detect a difference if it does exist.

Visual hallucinations in 246-km mountain ultra-marathoners: An observational study.

Ultra-marathons are typically held over harsh terrains such as mountains, deserts, or other wilderness, and place severe demands on the physical and psychological capabilities of participants. Adventure-race competitors commonly report hallucinations. The goal of this study was to gain insight into visual hallucinations (VHs) during a mountain ultra-marathon. Thirty-one Taiwanese runners who participated in the 2018 Run Across Taiwan Ultra-Marathon, which spans 246 km with an altitude difference of 3266 m and an overall cut-off time of 44 h, volunteered for this study. Self-reported questionnaires on sleep duration, hallucinatory experiences, clinical symptoms of cold- and heat-related illnesses, and the 2018 Lake Louise Acute Mountain Sickness (AMS) Score were recorded prerace, during the summit, immediately postrace, and 3-days postrace. Hematological samples were collected 1 week before, immediately after, and 3 days after the race. Eight ultra-marathoners (six males and two females; seven finishers and one withdrawer) were recruited. Three out of eight (37.5%) subjects (two males and one female) reported experiencing VHs during the last 60 km. Three out of five (60%) lower-ranked subjects experienced VHs. All eight runners slept for <30 min during the race. None of the runners presented with headache either during or after the race to meet the criteria for AMS. None of the runners suffered an abnormal thermoregulatory response or a hypoglycemic episode throughout the ultra-marathon. The changes in blood osmolality immediately postrace were subclinical, despite being statistically significant. Among the three runners with VHs, none presented with severe dehydration or dysnatremia immediately postrace. High-altitude exposure, hyper/hypothermia, dehydration, dysnatermia, or hypoglycemia did not seem to contribute to hallucination onset in our subjects during the event. VHs of ultra-marathoners may be associated with excessive physical exertion and sleep deprivation.

Molecular dynamics simulations of 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide clusters and nanodrops.

Atomistic molecular dynamics simulations of small clusters and nanodroplets of the ionic liquid 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide [EMIM-Tf2N] subject to an external electric field were performed. A 125-ion-pair droplet was found to be nearly spherical with an isotropic distribution of cations and anions under vacuum conditions. The droplet was subjected to external electric fields of varying strength, and ion emission events were observed. The initially spherical droplet is elongated along the electric field axis, resulting in nonspherical behavior and increased net dipole values after the application of strong electric fields. The critical electric field required for ion field emission was determined to be 0.985 V/nm, in agreement with the experimental value of 1.0 V/nm. Excellent agreement is found in the prediction of ionic emission products for a neutral 125-ion-pair droplet of the ionic liquid at an electric field strength of 1.2 V/nm when compared to the results of two independent experiments. Small ionic liquid clusters were investigated with respect to their thermal stabilities and were found to be thermally stable well above room temperature. The role of electric fields in the dissociation of small charged ion clusters was also investigated.

The impact of physical fitness and body mass index in children on the development of acute mountain sickness: A prospective observational study.

BACKGROUND: Acute mountain sickness (AMS) is commonly found among people traveling above 2500 m. We investigated whether the occurrence of AMS is related to differences in individual physical fitness and BMI in subjects 11-13 years of age. METHODS: This study was conducted at Xue Mountain, Taiwan (elevation of 3886 m) between June 13, 2011 and June 17, 2011. Subjects were asked to ascend from Taipei City (25 m) to the summit (3886 m) over 3 days and 2 nights. Gender, age, weight, height, and fitness index (determined using a 3-minute step test) were recorded at sea level before ascent. The Lake Louise AMS score was used to record symptoms and diagnose AMS. RESULTS: A total of 179 subjects (mean age: 11.8 years; 102 males, 77 females) were included in the analysis. A total of 44.7% of subjects were diagnosed with AMS. Male gender (p = 0.004) and elevated body mass index (BMI) (p < 0.001) were each associated with the development of AMS. However the physical fitness index was comparable in subjects with and without AMS (67.8 ± 10.1 vs. 68.0 ± 9.3, p = 0.9). CONCLUSIONS: This study shows that both BMI and male gender were associated with the development of AMS in 11-13 year old children. Physical fitness was not associated with the occurrence of AMS.

Effects of 100-km ultramarathon on acute kidney injury.

OBJECTIVE: To evaluate the prevalence and characteristics of acute kidney injury (AKI) in 100-km ultramarathon runners. DESIGN: Prospective observational study. SETTING: The 2011 Soochow University ultramarathon, in which each athlete ran for 100 km. PARTICIPANTS: All Taiwanese entrants who participated in the 100-km race and lived in the northern part of Taiwan were invited to participate in the study. MAIN OUTCOME MEASURES: Acute kidney injury was defined using the Acute Kidney Injury Network criteria. Blood and urine samples were collected 1 week before, immediately after, and 1 day after the race. RESULTS: Immediately after the race, 85% (22) of the 26 subjects were diagnosed with AKI, 65% (16) with moderate dehydration, 23% (6) with muscle cramps, and 12% (3) with hematuria. Body weight was significantly decreased from prerace to all postrace measurements. Plasma levels of potassium ion, creatinine, renin, and aldosterone were significantly elevated immediately after the race and then significantly reduced 1 day after the race. Changes in plasma levels of sodium, creatine kinase, and creatine kinase-MB, as well as urine potassium and creatinine, were indicative of AKI. CONCLUSIONS: Transient AKI and muscle cramps are very common in 100-km ultramarathon runners. All transient ultra-runners who developed AKI in this study recovered their renal function 1 day later. CLINICAL RELEVANCE: Ultramarathon running is associated with a wide range of significant changes in hematological parameters, several of which can be associated with potentially serious renal and physiological abnormalities.

Rate of ascent and acute mountain sickness at high altitude.

OBJECTIVE: To examine the effect of ascent rate on the induction of acute mountain sickness (AMS) in young adults during a climb to Jiaming Lake (3350 m) in Taiwan. DESIGN: Prospective, nonrandomized. SETTING: Climb from 2370 to 3350 m. PARTICIPANTS: Young adults (aged 18 to 26 years) (N = 91) chose to participate in either the fast ascent (3 days; n = 43) or slow ascent (4 days; n = 48) group (1 and 2). ASSESSMENT OF RISK FACTORS: Two criteria were used to define AMS. A Lake Louise score ≥3 and Lake Louise criteria [in the setting of a recent gain in altitude, the presence of headache and at least 1 of gastrointestinal discomfort (anorexia, nausea, or vomiting), fatigue or weakness, dizziness or lightheadedness, or difficulty sleeping]. MAIN OUTCOME MEASURES: Heart rate, blood oxygen saturation (SaO2), and symptoms of AMS were monitored each morning and evening. RESULTS: Baseline characteristics were similar between groups, except for significant differences in history of alcohol consumption (P = 0.009) and climbing experience above 3000 m (P < 0.001). The incidence of AMS was not associated with the rate of ascent. Acute mountain sickness was most prevalent in group 1 on day 2 in the evening and in group 2 on day 3 in the evening. In both groups, AMS correlated with the initial reduction in SaO2. Body mass index (BMI) >24 kg/m was identified as a significant risk factor for AMS. CONCLUSIONS: The development of AMS was closely associated with an initial reduction in SaO2. A BMI >24 kg/m also contributed to the occurrence of AMS. CLINICAL RELEVANCE: These findings indicate that factors other than ascent rate should be considered when trying to ameliorate the risk of AMS.

High myopia at high altitudes.

Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS (r pb = 0.448, p = 0.019) and the presence of headache symptoms (r pb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

How to differentiate spontaneous intramural intestinal hemorrhage from acute mesenteric ischemia.

OBJECTS: The purpose of our study was to assess the diagnostic values of laboratory tests to differentiate spontaneous intramural intestinal hemorrhage (SIIH) from acute mesenteric ischemia (AMI) after abdominal computed tomography (CT) survey in the emergency department (ED). METHOD: We retrospectively included 76 patients diagnosed SIIH or AMI after abdominal CT. RESULTS: The mean ages of 28 SIIH patients and 48 AMI patients were 75.9 ± 13.7 years and 75.8 ± 11.6 years, respectively. Patients with SIIH had significantly higher rate of Coumadin use (P < .001) and localized tenderness (P < .05). In laboratory findings, SIIH patients had prolonged prothrombin time (PT) (83.6 ± 30.0 vs. 13.4 ± 3.2, P < .001), lower blood urea nitrogen (P < .05), lower creatinine (P < .05), and lower creatine kinase (P < .05). Prolonged PT showed good discriminative value to differentiate acute abdomen patients with SIIH from AMI after abdominal CT, with an area under the receiver operating characteristic curve of 0.980 (95% confidence interval, 0.918-0.998; P < .0001). Prolonged PT cut-off value of ≧22.5 seconds had a sensitivity of 92.9% and a specificity of 100%. Logistic regression analysis identified prolonged PT as an independent predictor of SIIH (odds ratio, OR, 22.2; P = .007). CONCLUSION: Abdominal pain patients with either SIIH or AMI are rare in the ED, but abdominal CT sometimes cannot help to differentiate them due to similar CT findings. Prolonged PT might help emergency physicians and surgeons differentiate SIIH from AMI in such cases.

Different duration of high-altitude pre-exposure associated with the incidence of acute mountain sickness on Jade Mountain.

OBJECTIVE: The objective of this study is to determine the association between the duration of high-altitude (>3000 m) pre-exposure and acute mountain sickness (AMS) incidence. METHODS: A prospective observational study was conducted on 2 random days each month from April 2007 to March 2008 at Paiyun Lodge (3402 m), Jade Mountain, Taiwan. Demographic data, prior AMS history, symptoms, and scores and the days and times of high-altitude pre-exposure within the preceding 2 months were obtained from lowland (<1500 m) trekkers. RESULTS: Totally, 1010 questionnaires were analyzed; 106, 76, and 828 trekkers had pre-exposure lasting at least 3 days (group 1), less than 3 days (group 2), and 0 days (group 3), respectively. Acute mountain sickness incidence was significantly higher in groups 2 and 3 than in group 1 (21.70%, 35.53%, 37.08%, respectively; P = .008). Logistic regression analysis indicated a significantly lower AMS risk in group 1 (group 1, P = .004; odds ratio [OR], 0.479; 95% confidence interval [CI], 0.290-0.791; group 2, P = .226; OR, 0.725; 95% CI, 0.430-1.221). In group 1, 28 and 78 trekkers had single and intermittent multiple pre-exposure, respectively. There was no difference in the incidence or severity of AMS symptoms between single and intermittent multiple pre-exposure (AMS, P = .838; headache, P = .891; dizziness or lightheadedness, P = .414; fatigue and/or weakness, P = .957; gastrointestinal symptoms, P = .257; difficulty sleeping, P = .804; AMS score, P = .796). CONCLUSIONS: High-altitude pre-exposure lasting at least 3 days within the preceding 2 months was associated with a significant lower AMS incidence during a subsequent ascent among Jade Mountain trekkers.

Effect of ultramarathon running on iron metabolism.

BACKGROUND: Iron is a vital trace element for energy production and oxygen transportation; importantly, it is essential to athletic performance. Maintaining iron balance is tightly controlled at systemic and cellular levels. This study aimed to determine serum iron tests, hepcidin levels, and cellular iron import and export activities in peripheral blood mononuclear cells (PBMCs) in ultramarathon runners to elucidate the association of systemic inflammation response and iron metabolism. METHODS: Sixteen amateur runners were enrolled. Blood samples were taken 1 week before, immediately, and 24 h after the run. Plasma hepcidin levels were measured by enzyme-linked immunosorbent assay. The expression levels of divalent metal iron transporter 1 (DMT1), ZRT/IRT-like protein 14 (ZIP14), transferrin receptor 1 (TfR1), and ferroportin (FPN) in PBMCs were measured using real-time quantitative reverse transcription-polymerase chain reaction. RESULTS: Serum iron concentrations and transferrin saturation significantly decreased immediately after the race and dramatically recovered 24 h post-race. Serum ferritin levels had a statistically significant rise immediately after the race and remained high 24 h after the completion of the race. Ultramarathons were associated with increased plasma interleukin-6 concentrations corresponding to the state of severe systemic inflammation and therefore boosted plasma hepcidin levels. The expression levels of DMT1 and FPN mRNA were markedly decreased immediately and 24 h after the race. The ZIP14 and TfR1 mRNA expression in PBMCs significantly decreased immediately after the race and returned to the baseline level at 24 h post-race. Positive significant correlations were observed between plasma hepcidin and ferritin levels. CONCLUSION: Iron homeostasis and systemic inflammatory response are closely interconnected. Cellular iron import and export mRNA activities in PBMCs were acutely inhibited during an ultramarathon.

Chemi-luminescence measurements of hyperthermal Xe+/Xe2+ + NH3 reactions.

Luminescence spectra are recorded for the reactions of Xe(+) + NH(3) and Xe(2+) + NH(3) at energies ranging from 11.5 to 206 eV in the center-of-mass (E(cm)) frame. Intense features of the luminescence spectra are attributed to the NH (A (3)Π(i)-X (3)Σ(-)), hydrogen Balmer series, and Xe I emission observable for both primary ions. Evidence for charge transfer products is only found through Xe I emission for both primary ions and NH(+) emission for Xe(2+) primary ions. For both primary ions, the absolute NH (A-X) cross section increases with collision energy before leveling off at a constant value, approximately 9 × 10(-18) cm(2), at about 50 eV while H-α emission increases linearly with collision energy. The nascent NH (A) populations derived from the spectral analysis are found to be independent of collision energy and have a constant rotational temperature of 4200 K.

The changes of electroencephalography in mountaineers on Mount Jade, Taiwan: An observational study.

BACKGROUND: The diagnosis of acute mountain sickness, which lacks a reliable and objective diagnostic tool, still depends on the clinical symptoms and signs and remains a major threat and unpredictable disease affecting millions of mountaineers. OBJECTIVES: To record electroencephalography signals with small, convenient, wireless equipment and to test whether electroencephalography parameters, which are more sensitive and reliable markers, could predict the symptoms of acute mountain sickness. METHODS: Twenty-five participants were enrolled and separated into two groups to climb Mount Jade in Taiwan. We collected electrocardiography signals and arterial oxygen saturation data at ground, moderate (2,400 m), and high altitude (3,400 m). A spectral analysis of the electrocardiography was performed to assess the study subjects' electroencephalography activity at different frequencies (α, ß, θ, δ) and the mean power frequency of electrocardiography. The clinical symptoms and Lake Louise Acute Mountain Sickness scores of the subjects were recorded for comparison. RESULTS: A significant change in the δ power of electroencephalography was recorded in subjects ascending from the ground to a high altitude of 3,400 m in a 4-day itinerary. In addition, between the two groups of subjects with and without acute mountain sickness (Lake Louise Acute Mountain Sickness scores < 3 and ≥ 3), the δ power of electroencephalography at the fronto-parietal 1 and parietal 3 electrodes at moderate altitude as well as the changes of δ power and mean power frequency of electrocardiography over parietal 4 at high altitude showed a significant difference. At moderate altitude, the increasing δ power of electroencephalography at the parietal 4 electrode was related to the headache symptom of acute mountain sickness before ascending to high altitude. CONCLUSION: At moderate altitude, the δ power increase of electroencephalography at the P4 electrode could be a predictor of acute mountain sickness symptoms before ascending to high altitude. Thus, electroencephalography had the potential to identify the risk of acute mountain sickness.

Luminescence measurements of Xe(+) + N2 and Xe(2+) + N2 hyperthermal charge transfer collisions.

Luminescence spectra are recorded for collisions between Xe(+)/Xe(2+) and molecular nitrogen at energies ranging from 4.5 to 316 eV in the center-of-mass frame. In the Xe(+) + N(2) collision system, evidence for luminescent charge-transfer products is only found through Xe I emission lines. The most intense features of the luminescence spectra are attributed to atomic N emissions observed above ∼20 eV. Intense N(2)(+) A (2)Π(u) - X(2)Σ(g)(+) and B(2)Σ(u)(+) - X(2)Σ(g)(+) radiance is observed from Xe(2+) + N(2) collisions. The B state formation cross section decreases with collision energy until 20 eV, after which it becomes independent of impact energy with an approximate value of 3 Å(2). The cross section for N(2) (+) A (ν > 0) formation increases with energy until 20 eV, after which it remains nearly constant at ∼1 Å(2). The N(2)(+) product vibrational distributions extracted from the spectra are non-Franck-Condon for both electronic product states at low collision energies. The distributions resemble a Franck-Condon distribution at the highest energies investigated in this work.

Communication: rovibrationally selected study of the N2+(X; v+=1, N+= 0-8) + Ar charge transfer reaction using the vacuum ultraviolet laser pulsed field ionization-photoion method.

By employing an electric field pulsing scheme for vacuum ultraviolet laser pulsed field ionization-photoion (PFI-PI) measurements, we have been able to prepare a rovibrationally selected PFI-PI beam of N(2)(+)(v(+) = 1, N(+)) with not only high intensity and high quantum state purity, but also high kinetic energy resolution, allowing absolute total cross sections [σ(v(+) = 1, N(+))] for the N(2)(+)(X; v(+) = 1, N(+)) + Ar, N(+) = 0-8 charge transfer reaction to be measured at center-of-mass collision energies (E(cm)) down to thermal energies. The σ(v(+) = 1, N(+) = 0-8) values determined at E(cm) = 0.04-10.00 eV are in good agreement with the theoretical predictions based on the Landau-Zener-Stückelberg formulism. Taking into account the experimental uncertainties, the σ(v(+) = 1, N(+)), N(+) = 0-8, measured at E(cm) = 1.56 eV are found to be independent of N(+).

Immunolocalization of chloride transporters to gill epithelia of euryhaline teleosts with opposite salinity-induced Na+/K+-ATPase responses.

Opposite patterns of branchial Na(+)/K(+)-ATPase (NKA) responses were found in euryhaline milkfish (Chanos chanos) and pufferfish (Tetraodon nigroviridis) upon salinity challenge. Because the electrochemical gradient established by NKA is thought to be the driving force for transcellular Cl(-) transport in fish gills, the aim of this study was to explore whether the differential patterns of NKA responses found in milkfish and pufferfish would lead to distinct distribution of Cl(-) transporters in their gill epithelial cells indicating different Cl(-) transport mechanisms. In this study, immunolocalization of various Cl(-) transport proteins, including Na(+)/K(+)/2Cl(-) cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 1 (AE1), and chloride channel 3 (ClC-3), were double stained with NKA, the basolateral marker of branchial mitochondrion-rich cells (MRCs), to reveal the localization of these transporter proteins in gill MRC of FW- or SW-acclimated milkfish and pufferfish. Confocal microscopic observations showed that the localization of these transport proteins in the gill MRCs of the two studied species were similar. However, the number of gill NKA-immunoreactive (IR) cells in milkfish and pufferfish exhibited to vary with environmental salinities. An increase in the number of NKA-IR cells should lead to the elevation of NKA activity in FW milkfish and SW pufferfish. Taken together, the opposite branchial NKA responses observed in milkfish and pufferfish upon salinity challenge could be attributed to alterations in the number of NKA-IR cells. Furthermore, the localization of these Cl(-) transporters in gill MRCs of the two studied species was identical. It depicted the two studied euryhaline species possess the similar Cl(-) transport mechanisms in gills.

A guided-ion beam study of the reactions of Xe(+) and Xe(2+) with NH(3) at hyperthermal collision energies.

We have measured the absolute cross sections for reactions of Xe(+) and Xe(2+) with NH(3) at collision energies in the range from near-thermal to ∼34 and ∼69 eV, respectively. For Xe(+), the cross section for charge transfer, the only exothermic channel, decreases from ∼200Å(2) below 0.1 eV to ∼12Å(2) at the highest energies studied. The production of NH(3) (+) is the only channel observed below 5 eV, above which a small amount of NH(2) (+) is also formed. In Xe(2+) reactions, the main products observed are NH(3) (+) and NH(2) (+). The charge transfer cross section decreases monotonically from ∼80 to ∼6Å(2) over the studied energy range. The NH(2) (+) cross section is similar to the charge transfer cross section at the lowest energies, and exhibits a second component above 0.4 eV, with a maximum of 65Å(2) at 0.7 eV, above which the cross section decreases to ∼30Å(2) at the highest energies studied. At energies above 10 eV, a small amount of NH(+) is also observed in Xe(2+) collisions. Product recoil velocity distributions were determined at selected collision energies, using guided-ion beam time-of-flight methods.