[Factors Affecting Nitrate Concentrations and Nitrogen and Oxygen Isotope Values of Effluents from Waste Water Treatment Plant]

Urban domestic sewage is one of the important nitrate (NO^-₃) sources for surface water; however, their NO^-₃ concentrations and nitrogen and oxygen isotope values (δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃) remain unclear, and the factors affecting NO^-₃ concentrations and δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃ values of effluents in the waste water treatment plant (WWTP) are still unknown. Water samples in the Jiaozuo WWTP were collected to illustrate this question. Influents, clarified water in the secondary sedimentation tank (SST), and effluents of the WWTP were sampled every 8 h. The ammonia (NH⁺₄) concentrations, NO^-₃ concentrations, and δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃ values were analyzed to elucidate the nitrogen transfers through different treatment sections and illustrate the factors affecting the effluent NO^-₃ concentrations and isotope ratios. The results indicated that ① the mean NH⁺₄ concentration was (22.86±2.16) mg·L^-1 in the influent and decreased to (3.78±1.98) mg·L^-1 in the SST and continuously reduced to (2.70±1.98) mg·L^-1 in the effluent of the WWTP. The median NO^-₃ concentration was 0.62 mg·L^-1 in the influent, and the average NO^-₃ concentration increased to (33.48±3.10) mg·L^-1 in the SST and gradually increased to (37.20±4.34) mg·L^-1 in the effluent of the WWTP. ② The mean values of δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃ were (17.1±10.7)‰ and (19.2±2.2)‰ in the influent of the WWTP, the median values of δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃ were 11.9‰ and 6.4‰ in the SST, and the average values were (12.6±1.9)‰ and (5.7±0.8)‰ in the effluent of the WWTP. ③ The NH⁺₄ concentrations of influent had significant differences compared to those in the SST and the effluent (P<0.05). The reduction of NH⁺₄ concentrations in the SST was due to the above nitrification during the aerobic treatment process, which transferred NH⁺₄ to NO^-₃. The NH⁺₄ concentrations in the SST had no significant differences with that in the effluent of the WWTP (P>0.05). ④ The NO^-₃ concentrations in the influent had significant differences with those in the SST and the effluent (P<0.05), and minor NO^-₃ concentrations but relatively high δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃ values in the influent were probably due to denitrification during the pipe sewage transportation. The obviously increased NO^-₃ concentrations (P<0.05) but decreased δ¹⁸O-NO^-₃ values (P<0.05) in the SST and the effluent resulted from water oxygen incorporation during the nitrification. The above results confirmed the impacts of aerobic and anaerobic treatment processes on NO^-₃ concentrations and isotope ratios of effluent from the WWTP and provided scientific basis for the identification of sewage contributions to surface water nitrate via average δ¹⁵N-NO^-₃ and δ¹⁸O-NO^-₃ values.

[Dissolved Ion Concentrations and Isotope Values in Agricultural Fertilizer Locally Applied in Henan Province]

Agricultural fertilizers (AFs) have provided vegetation with necessary nutrients, but unabsorbed constituents have been retarded in soil, potentially affecting the quality of adjacent surface water and groundwater. AFs element contents and stable isotope compositions have often been utilized to assess and calculate AFs pollution to nitrate and sulfate in surface water and groundwater; however, due to various AFs applied, the dissolved ion concentrations and isotope ratios are still unknown. This study collected commercial AF widely utilized in Henan province, China, to constrain their ion concentrations and isotope values. The dissolved ions (1 g AFs dissolved in 1 L ultrapure water), sulfate sulfur, and oxygen isotope values(δ³⁴S and δ¹⁸O) were analyzed, and total nitrogen (TN) contents coupled with nitrogen isotope values(δ¹⁵N) in solid AFs were determined to elucidate their elemental and isotopic compositions. These characteristics provided a scientific basis for further assessing their contributions to surface water and groundwater contaminations. The results indicated that pH values in the AFs solutions varied from 3.6 to 10.2, with a mean value of 6.7±1.5 (n=30, 1σ). Sulfate (SO₄^2-) and nitrate (NO₃^-) concentrations ranged from 4.38 mg·L^-1 to 827.29 mg·L^-1 and from 1.34 mg·L^-1 to 208.90 mg·L^-1, with median values of 192.80 mg·L^-1 and 13.51 mg·L^-1 and average values of (256.19±239.83) mg·L^-1 (n=30) and (37.07±53.21) mg·L^-1 (n=29), respectively. Dissolved sulfate δ³⁴S and δ¹⁸O values in AFs varied from -3.5‰ to 19.0‰ and from 6.7‰ to 18.5‰, with median values of 4.1‰ and 10.1‰ and mean values of (5.8±5.5)‰ (n=22, 1σ) and (10.7±2.7)‰ (n=22, 1σ), respectively. TN and δ¹⁵N values in AFs ranged from 0.5% to 38.9% and from -2.7‰ to 3.4‰, with median values of 13.3% and 0.0‰ and average values of (14.8±9.3)% (n=25) and 0.0±1.5‰ (n=24, 1σ), respectively. The lower averaged δ³⁴S values and positive averaged δ¹⁸O values potentially resulted from sulfuric acids added as raw materials, giving rise to a negative relationship between pH values and SO₄^2- concentrations (P<0.05). The δ¹⁵N values of AFs were close to that of air N₂, corresponding to the fact that NO₃^--N and NH₄⁺-N were synthesized via air N₂. Our results revealed the dissolved ion concentrations of SO₄^2-, NO₃^-, and NH₄⁺ and their δ³⁴S, δ¹⁸O, and δ¹⁵N values of typically applied AFs in Henan province, which provided the scientific basis for studying the AFs contributions to SO₄^2- and NO₃^- pollutions in surface water and groundwater surroundings.

[Predictive value of plasma TMAO combined with NT-proBNP on the prognosis and length of hospitalization of patients with ischemic heart failure]

Objective: To explore the value of the assessment of plasma trimethylamine N-oxide (TMAO) combined with N-terminal pro-B-type natriuretic peptide (NT-proBNP) on predicting the all-cause mortality, length of hospitalization, and hospital cost in ischemic heart failure (IHF) patients. Methods: This prospective cohort study included 189 patients (157 males, mean age (64.0±10.5) years) with a left ventricular ejection fraction<45% caused by coronary artery disease, who hospitalized in our department from March 2016 to December 2020. Baseline data, including demographics, comorbid conditions and laboratory examination, were analyzed. The cumulative rate of all-cause mortality was evaluated using the Kaplan-Meier method and compared between the groups according to the log-rank test. Relative risks were reported as hazard ratios (HR) and 95% confidence interval (95%CI) calculated using the Cox proportional-hazards analysis, with stepwise adjustment for covariables. Spearman correlation analysis was then performed to determine the relationship between TMAO combined with NT-proBNP and length of hospitalization and hospital cost. Results: There were 50 patients in the low TMAO+low NT-proBNP group, 89 patients in high TMAO or high NT-proBNP group, 50 patients in high TMAO+high NT-proBNP group. The mean follow-up period was 3.0 years. Death occurred in 70 patients (37.0%), 27 patients (54.0%) in high TMAO+high NT-proBNP group, 29 patients (32.6%) in high TMAO or high NT-proBNP group and 14 patients (28.0%) in low TMAO+low NT-proBNP group. TMAO, in combination with NT-proBNP, improved all-cause mortality prediction in IHF patients when stratified as none, one or both biomarker(s) elevation, with the highest risk of all-cause mortality in high TMAO+high NT-proBNP group (HR=3.62, 95%CI 1.89-6.96, P<0.001). ROC curve analysis further confirmed that TMAO combined with NT-proBNP strengthened the prediction performance on the risk of all-cause death (AUC=0.727(95%CI 0.640-0.813), sensitivity 55.0%, characteristic 83.1%). Spearman correlation analysis showed that IHF patients with high TMAO and high NT-proBNP were positively associated with longer duration of hospitalization (r=0.191,P=0.009), but not associated with higher hospital cost (r=0.030, P=0.686). Conclusions: TMAO combined with NT-proBNP are valuable prediction tool on risk stratification of patients with IHF, and those with two biomarkers elevation face the highest risk of mortality during follow-up period, and are associated with the longer hospital stay.

[Modeling of sugar content based on NIRS during cider-making fermentation]

The sugar content and the matrix always are being changed during cider-making fermentation. In order to measure and monitor sugar content accurately and rapidly, it is necessary for the spectra to be sorted. Calibration models were established at different fermentation stages based on near infrared spectroscopy with artificial neural network. NIR spectral data were collected in the spectral region of 12 000-4 000 cm(-1) for the next analysis. After the different conditions for modeling sugar content were analyzed and discussed, the results indicated that the calibration models developed by the spectral data pretreatment of straight line subtraction(SLS) in the characteristic absorption spectra ranges of 7 502-6 472.1 cm(-1) at stage I and 6 102-5 446.2 cm(-1) at stage II were the best for sugar content. The result of comparison of different data pretreatment methods for establishing calibration model showed that the correlation coefficients of the models (R2) for stage I and II were 98.93% and 99.34% respectively and the root mean square errors of cross validation(RMSECV) for stage I and II were 4.42 and 1.21 g x L(-1) respectively. Then the models were tested and the results showed that the root mean square error of prediction (RMSEP) was 4.07 g x L(-1) and 1.13 g x L(-1) respectively. These demonstrated that the models the authors established are very well and can be applied to quick determination and monitoring of sugar content during cider-making fermentation.

Development of cross-resistance to tamoxifen in raloxifene-treated breast carcinoma cells

Selective estrogen receptor modifiers (SERMs) are used chronically in the treatment of breast cancer and osteoporosis but some patients become resistant, at which point second-line SERMs are considered as options. Because the use of SERMs is increasing and breast cancer is so common, we tested the hypothesis that treatment with SERMs can induce cross-resistance to other SERMs. We used three cultured breast carcinoma cell lines (MCF-7, ZR-75-1, and T47D) which are estrogen-receptor-positive (ER+) and are prone to developing resistance to hormonal treatment. Cell lines were exposed to increasing doses of raloxifene. Raloxifene-resistant clones were selected and tested for cross-resistance to tamoxifen. Compared to untreated cells, raloxifene-resistant clones showed an increased IC50 (reduced potency) of about 15,000-fold with no apparent change in maximal inhibition of cell growth. These same raloxifene-resistant clones were also about 15-fold more resistant to the growth-inhibiting effects of tamoxifen. While the resistance to tamoxifen is considerably less marked (1000-fold less), it is large enough to raise the question as to whether patients who become resistant to raloxifene will benefit by switching to tamoxifen or vice versa.

Impact of 1 wk of diabetes on the regulation of myocardial carbohydrate and fatty acid oxidation

The aim of this study was to investigate the effect of increasing exogenous palmitate concentration on carbohydrate and palmitate oxidation in hearts from control and 1-wk diabetic rats. Hearts were perfused with glucose, [3-(13)C]lactate, and [U-(13)C]palmitate. Substrate oxidation rates were determined by combining (13)C-NMR glutamate isotopomer analysis of tissue extracts with measurements of oxygen consumption. Carbohydrate oxidation was markedly depressed after diabetes in the presence of low (0.1 mM) but not high (1.0 mM) palmitate concentration. Increasing exogenous palmitate concentration 10-fold resulted in a 7-fold increase in the contribution of palmitate to energy production in controls but only a 30% increase in the diabetic group. Consequently, at 0.1 mM palmitate, the rate of fatty acid oxidation was higher in the diabetic group than in controls; however, at 1.0 mM fatty acid oxidation, it was significantly depressed. Therefore, after 1 wk of diabetes, the major differences in carbohydrate and fatty acid metabolism occur primarily at low rather than high exogenous palmitate concentration.

Preferential inhibition of lactate oxidation relative to glucose oxidation in the rat heart following diabetes

OBJECTIVE

Alterations in myocardial metabolism occur early after the onset of diabetes suggesting that they may play a role in the development of cardiac dysfunction. Inhibition of myocardial pyruvate dehydrogenase (PDH), glucose transport and glycolysis have all been reported following diabetes. In vivo lactate is also a potential source of energy for the heart and its oxidation should not be affected by changes in glucose transport and glycolysis. Therefore, the objective of this study, was to test the hypothesis that following diabetes the inhibition of glucose oxidation would be greater than the inhibition of lactate oxidation.

METHODS

Hearts from control and one-week-old diabetic rats were perfused with [1-13C]glucose (11 mmol/l) alone, [1-13C]glucose plus lactate (0.5 mmol/l) or glucose plus [3-13C]lactate (0.5 or 1.0 mmol/l) as substrates. Glucose and lactate oxidation rates were determined by combining 13C-NMR glutamate isotopomer analysis of tissue extracts with measurements of oxygen consumption.

RESULTS

In diabetic hearts perfused with glucose alone, glucose oxidation was decreased compared to controls (0.31 +/- 0.08 vs. 0.71 +/- 0.11 mumoles/min/g wet weight; p < 0.05). Surprisingly, in hearts perfused with glucose plus 0.5 mmol/l lactate, there was no difference in glucose oxidation between control and diabetic groups (0.20 +/- 0.05 vs. 0.16 +/- 0.04 mumoles/min/g wet weight respectively). However, under these conditions lactate oxidation was markedly reduced in the diabetic group (0.89 +/- 0.18 vs. 0.24 +/- 0.05 mumoles/min/g wet weight; p < 0.05). At 1.0 mmol/l lactate oxidation was still significantly depressed in the diabetic group.

CONCLUSION

There was a greater decrease in lactate oxidation relative to glucose oxidation in hearts from diabetic animals. These results demonstrate that diabetes leads to a specific inhibition of lactate oxidation independent of its effects on pyruvate dehydrogenase.

Adenosine receptor blockade enhance glycolysis in hypoperfused guinea-pig myocardium

OBJECTIVE

This study tested the hypothesis that endogenous adenosine depresses anaerobic glycolysis in preischaemic and moderately ischaemic myocardium.

METHODS

Isolated, working guinea-pig hearts, perfused with glucose-fortified Krebs-Henseleit buffer, were subjected to 15 min mild hypoperfusion (coronary flow 60% of baseline) followed by 10 min ischaemia (coronary flow 20% of baseline). Adenosine A1 receptors were blocked with 8-p-sulfophenyl theophylline (8-SPT; 20 microM). Glucose oxidation and lactate production from exogenous glucose were assessed from 14CO2 and [14C]lactate formation, respectively, from [U-14C]glucose. Energy metabolites, glycolytic intermediates and glycogen were measured in extracts of stop-frozen preischaemic, mildly hypoperfused and ischaemic myocardium.

RESULTS

Adenosine receptor blockade did not affect left ventricular function assessed from heart rate x pressure product and pressure x volume work although coronary flow was slightly reduced. Adenosine receptor blockade increased glucose uptake (P < 0.05) by 100% during preischaemia and by 74% during mild hypoperfusion, and increased lactate production from exogenous glucose (P < 0.05) by 89% during preischaemia and fourfold during mild hypoperfusion, but did not stimulate glucose oxidation under any condition. Glycogen degradation was not increased by adenosine receptor blockade during ischaemia. Crossover plots of glycolytic intermediates revealed that phosphofructokinase was activated by adenosine receptor blockade at all three levels of perfusion.

CONCLUSION

Endogenous adenosine attenuates anaerobic glycolysis in normally perfused, hypoperfused and ischaemic myocardium by blunting phosphofructokinase activity; this effect is mediated by adenosine A1 receptors.

Stability of high-energy phosphates in right ventricle: myocardial energetics during right coronary hypotension

This study was conducted to determine if mechanisms that reduce right coronary (RC) blood flow (RCBF) and right ventricular (RV) oxygen consumption (MVO2) during moderate RC hypotension preserve RV high-energy phosphates. RC arteries of anesthetized dogs were cannulated and perfused with arterial blood supplied by a pressurized extracorporeal circuit. RC perfusion pressure (RCPP) was either kept constant at 100 mmHg or reduced to 60 or 30 mmHg for 20 min followed by a freeze-clamp biopsy of RV. Left ventricular (LV) biopsy was also performed to compare energy metabolism between RV and LV.RCBF and MVO2 significantly decreased when RCPP was reduced to 60 mmHg, but RV segment shortening (%SS) was unchanged; ATP, creating phosphate (CrP) and phosphorylation state of CrP ([CrP]/[Cr][Pi]) did not differ from control values. RV %SS, CrP, and phosphorylation state fell markedly at 30 mmHg RCPP. At 100 mmHg RCPP, CrP phosphorylation state in RV was only 35% of that in LV. These results indicate that RV increases its energetic efficiency without significant changes in high-energy phosphates or CrP phosphorylation state during moderate RC hypotension. Furthermore, the RV myocardium maintains a much lower energy level than LV myocardium, commensurate with its lower energy requirements.

Does interstitial adenosine mediate acute hibernation of guinea pig myocardium?

OBJECTIVE

The aim was to test the role of interstitial adenosine in protective downregulation of myocardial energy demand during myocardial hibernation.

METHODS

Isolated working guinea pig hearts, perfused with glucose fortified Krebs-Henseleit, were subjected to 60 min global low flow ischaemia followed by 30 min reperfusion. Left ventricular performance was assessed from heart rate-developed pressure product and pressure-volume work. Cytosolic energy level was indexed by creatine phosphate and ATP phosphorylation potentials measured in snap frozen myocardium. Lactate and purine nucleosides (adenosine, inosine) were measured in venous effluent.

RESULTS

When coronary flow was lowered by 80% for 60 min, heart rate-pressure product and pressure-volume work fell 87% and 75%, respectively, and stabilised at these low levels, but fully recovered when flow was restored. Myocardial ATP phosphorylation potential fell by 67% during the first 10 min of ischaemia, but subsequently recovered to preischaemic levels despite continuing ischaemia, indicating down-regulation of myocardial energy demand. Lactate release increased about 10-fold during ischaemia and remained increased until reperfusion. Purine nucleoside release varied reciprocally with phosphorylation potential, peaking at 10 min of ischaemia, then gradually returning to the preischaemic level during the subsequent 50 min of ischaemia. The ecto 5'-nucleotidase inhibitor alpha,beta-methylene adenosine 5'-diphosphonate (50 microM) decreased ischaemic purine nucleoside release by 41%, but did not attenuate postischaemic contractile recovery. The unspecific adenosine receptor antagonist 8-p-sulphophenyl theophylline (8-SPT, 20 microM) doubled ischaemic lactate release and lowered coronary venous purine nucleoside release by 21%. 8-SPT increased phosphorylation potential at 10 min ischaemia relative to untreated hearts, but blunted the subsequent rebound of phosphorylation potential. 8-SPT treatment during ischaemia resulted in a significantly higher cytosolic phosphorylation potential at 30 min of reperfusion, but did not affect postischaemic contractile function.

CONCLUSIONS

We conclude that activation of adenosine receptors results in recovery of cytosolic energy level of moderately ischaemic working myocardium, but this energetic recovery is not solely responsible for postischaemic contractile recovery.