Nutrient concentrations and accumulations in precipitation over the north central region

The many facets of plant nutrients (e.g., N, P, and S) in the biosphere have become major environmental issues within the past decade. This concern is justified because of the increasing contamination of air and water resources by various substances on local and regional levels, especially in areas close to point sources. Little information is available, however, on variation in the amounts and concentrations of some of the substances present in air and natural water in various parts of the United States. Such information is essential for a better understanding of the transport and perhaps the fates of pollutants in the biosphere. The atmospheric component of the N and S cycles often can be a significant part of the various pools of their respective cycles (Allison, 1965; Erickson, 1963; Feth, 1966; Gambell and Fisher, 1964; Meetham, 1950; Robinson and Robbins, 1970), but the atmospheric component of the P cycle seems to be of minor significance to the cycling of this element in the environment. Among the various chemical elements present in precipitation (e.g., N, S, K, Cl, and Ca), N and S deserve special attention because N added by precipitation may contribute to nitrate pollution of surface and ground water. Sulfur and N may cause acid rain that can lead to increased leaching from soils of Ca and other nutrient elements, deterioration of aquatic ecosystems, damage to vegetation and buildings, and other agricultural and urban problems. On the other hand, the limited amounts of N and S brought down by precipitation might be useful to meet crop requirements for these elements in areas where soils have limited supplies of N and S (Allway et al., 1937; Erdman, 1923; Olson et al., 1973; Schuman and Burwell, 1974; Tabatabai and Bremner, 1972; Walker, 1969; Widdowson and Hanway, 1974)

A Simple Alkaline Hydrolysis Method for Estimating Nitrogen Mineralization Potential of Soils

A simple, precise and rapid alkaline hydrolysis method for determining nitrogen (N) availability index of soils is described. It involves direct steam distillation of 1 g field-moist soil and 1 M KOH, NaOH, LiOH or phosphate-borate buffer (pH 11.8) and the amount of NH4+-N released trapped in boric acid and its concentration determined successively every 5 min for a total of 40 min. The cumulative N hydrolyzed was fitted to a hyperbolic equation to determine the maximum hydrolyzable N (Nmax) and the time required to hydrolyze one-half of Nmax (Kt) by linear regression of the transformed data. First-order equation was also used to estimate the potentially hydrolyzable N (No), hydrolysis rate constant (k) and the time required to hydrolyze one-half of No (t1/2). Results showed that for each soil and reagent, Nmax and No values were similar, but differed significantly among soils, suggesting differences in the chemical nature or reactivity of organic N in the soils. In general, Nmax and No values ranged from 401 to 1667 mg kg-1 soil and accounted for 12-56% of total organic N in the soils. The Kt values ranged between 15 and 30 min. Among the reagents tested, KOH and NaOH showed the best promise for estimating the total hydrolyzable organic N pool in the soils. The Nmax and No values were significantly correlated with the amounts of N mineralized in two weeks under aerobic and anaerobic conditions at 30 oC, N released by 2 M KCl extraction at 80oC for 20 h, and the initial NH4+-N present in the soils. We concluded that direct steam distillation of soils with 1M KOH or NaOH offer a quick and precise mean for estimating the potentially mineralizable organic N pool and availability index in soils

Hyperbolastic modeling of tumor growth with a combined treatment of iodoacetate and dimethylsulphoxide

<p>Abstract</p> <p>Background</p> <p>An understanding of growth dynamics of tumors is important in understanding progression of cancer and designing appropriate treatment strategies. We perform a comparative study of the hyperbolastic growth models with the Weibull and Gompertz models, which are prevalently used in the field of tumor growth.</p> <p>Methods</p> <p>The hyperbolastic growth models H1, H2, and H3 are applied to growth of solid Ehrlich carcinoma under several different treatments. These are compared with results from Gompertz and Weibull models for the combined treatment.</p> <p>Results</p> <p>The growth dynamics of the solid Ehrlich carcinoma with the combined treatment are studied using models H1, H2, and H3, and the models are highly accurate in representing the growth. The growth dynamics are also compared with the untreated tumor, the tumor treated with only iodoacetate, and the tumor treated with only dimethylsulfoxide, and the combined treatment.</p> <p>Conclusions</p> <p>The hyperbolastic models prove to be effective in representing and analyzing the growth dynamics of the solid Ehrlich carcinoma. These models are more precise than Gompertz and Weibull and show less error for this data set. The precision of H3 allows for its use in a comparative analysis of tumor growth rates between the various treatments.</p

Clinical and multiple gene expression variables in survival analysis of breast cancer: Analysis with the hypertabastic survival model

BACKGROUND: We explore the benefits of applying a new proportional hazard model to analyze survival of breast cancer patients. As a parametric model, the hypertabastic survival model offers a closer fit to experimental data than Cox regression, and furthermore provides explicit survival and hazard functions which can be used as additional tools in the survival analysis. In addition, one of our main concerns is utilization of multiple gene expression variables. Our analysis treats the important issue of interaction of different gene signatures in the survival analysis. METHODS: The hypertabastic proportional hazards model was applied in survival analysis of breast cancer patients. This model was compared, using statistical measures of goodness of fit, with models based on the semi-parametric Cox proportional hazards model and the parametric log-logistic and Weibull models. The explicit functions for hazard and survival were then used to analyze the dynamic behavior of hazard and survival functions. RESULTS: The hypertabastic model provided the best fit among all the models considered. Use of multiple gene expression variables also provided a considerable improvement in the goodness of fit of the model, as compared to use of only one. By utilizing the explicit survival and hazard functions provided by the model, we were able to determine the magnitude of the maximum rate of increase in hazard, and the maximum rate of decrease in survival, as well as the times when these occurred. We explore the influence of each gene expression variable on these extrema. Furthermore, in the cases of continuous gene expression variables, represented by a measure of correlation, we were able to investigate the dynamics with respect to changes in gene expression. CONCLUSIONS: We observed that use of three different gene signatures in the model provided a greater combined effect and allowed us to assess the relative importance of each in determination of outcome in this data set. These results point to the potential to combine gene signatures to a greater effect in cases where each gene signature represents some distinct aspect of the cancer biology. Furthermore we conclude that the hypertabastic survival models can be an effective survival analysis tool for breast cancer patients

Elevated Tumor Lactate and Efflux in High-grade Prostate Cancer demonstrated by Hyperpolarized 13C Magnetic Resonance Spectroscopy of Prostate Tissue Slice Cultures.

Non-invasive assessment of the biological aggressiveness of prostate cancer (PCa) is needed for men with localized disease. Hyperpolarized (HP) 13C magnetic resonance (MR) spectroscopy is a powerful approach to image metabolism, specifically the conversion of HP [1-13C]pyruvate to [1-13C]lactate, catalyzed by lactate dehydrogenase (LDH). Significant increase in tumor lactate was measured in high-grade PCa relative to benign and low-grade cancer, suggesting that HP 13C MR could distinguish low-risk (Gleason score ≤3 + 4) from high-risk (Gleason score ≥4 + 3) PCa. To test this and the ability of HP 13C MR to detect these metabolic changes, we cultured prostate tissues in an MR-compatible bioreactor under continuous perfusion. 31P spectra demonstrated good viability and dynamic HP 13C-pyruvate MR demonstrated that high-grade PCa had significantly increased lactate efflux compared to low-grade PCa and benign prostate tissue. These metabolic differences are attributed to significantly increased LDHA expression and LDH activity, as well as significantly increased monocarboxylate transporter 4 (MCT4) expression in high- versus low- grade PCa. Moreover, lactate efflux, LDH activity, and MCT4 expression were not different between low-grade PCa and benign prostate tissues, indicating that these metabolic alterations are specific for high-grade disease. These distinctive metabolic alterations can be used to differentiate high-grade PCa from low-grade PCa and benign prostate tissues using clinically translatable HP [1-13C]pyruvate MR

Prevalence of high-risk human papillomavirus types among women screened for cervical cancer in yazd, iran, and comparison of cytology, histology, and colposcopy results

Background: Human Papillomavirus (HPV) is a DNA virus with more than 100 genotypes, at least 12 of which are high-risk and associated with high-grade cervical lesions. Data on the prevalence of high-risk HPV genotypes among women are not yet available for the total regions of Iran. Objectives: The present study aimed to determine the prevalence of high-risk HPV types among women screened for cervical carci-noma in Yazd and compare the cytology, histology, and colposcopy results. Methods: In this cross-sectional study, 402 women referring to gynecology clinics of Shahid Sadoughi University of Medical Sci-ences, Yazd, Iran, were selected. The Pap smear and HPV typing were performed on cervical samples. The high-risk HPV types were detected by the polymerase chain reaction (PCR)-based reverse blot hybridization assay. Colposcopy was carried out on patients with high-risk HPV types, and biopsies were taken for histological examination. Results: Among 402 women screened by HPV-PCR, 32 (7.97) women were positive for high-risk HPV types. Human papillomavirus 16 and HPV18 were the most frequent genotypes (46.9). The cytology, histology, and colposcopy results were abnormal in 56.2, 29.1, and 71.9 of patients, respectively. Pap smear had 100 sensitivity and 58.3 specificity for the detection of high-grade cervical lesions, while these values for colposcopy were 75 and 87.5, respectively. Conclusions: The frequency of high-risk HPV types was relatively low among women living in Yazd than in those from other provinces of Iran. A significant percentage of patients with HPV had normal cervical cytology and histology. Therefore, HPV typing is recommended to decrease the development of cervical cancer. Colposcopy had acceptable sensitivity and specificity for the detection of high-grade cervical lesions. © 2020, Author(s)