Stability of cefacetrile in milk samples with various fat content

The consumers should have access to food that is safe and free of contaminants. Unfortunately, the wide use of antibiotics in livestock, not only for medicinal purposes but also as illegal feed additives, may be the reason for emergence of the antibiotic residues in foodstuffs of animal origin. Milk is one of the most essential nutrients for humans during their lifetimes. Failure of the withdrawal periods, or what is highly prohibited but in spite of this increasingly practiced, addition of the antibiotics to milk in order to prolong its freshness, may lead to occurrence of their residues. Cefacetrile is a first generation cephalosporin that is commonly use for the treatment of bovine mastitis. The aim of this work was to determine the stability of cefacetrile in milk samples of different fat content, that is, 0 , 2 , 3.2 % UHT, 2 % pasteurized and ~3.9 % raw cattle milk, for 5 days. Two chromatographic methods were applied and compared for this purpose, that is, thin-layer chromatography and high-performance liquid chromatography. According to the results coming from HPLC-UV analysis, the stability of cefacetrile increase with the increase in the fat mass content in UHT milk. The cefacetrile level in pasteurized and raw cattle milk is similar to that in 3.2 % UHT milk. For the TLC method, this relation can be observed only in the second day of the analysis. The spiked milk samples analyzed by HPLC were deproteinized with MeCN and stored for 5 days of the experiment. Whereas, in the TLC-UV method, the spiked milk samples prepared in the first day of experiment were analyzed directly, without deproteinization. The lower stability of cefacetrile in milk samples observed from the TLC analysis can be related to its partial enzymatic decomposition.     

Comparison of the Adomian decomposition method and the variational iteration method in solving the moving boundary problem

In this paper, a comparison between two methods: the Adomian decomposition method and the variational iteration method, used for solving the moving boundary problem, is presented. Both of the methods consist in constructing the appropriate iterative or recurrence formulas, on the basis of the equation considered and additional conditions, enabling one to determine the successive elements of a series or sequence approximating the function sought. The precision and speed of convergence of the procedures compared are verified with an example.     

Flt3high and Flt3low CD34+ progenitor cells isolated from human bone marrow are functionally distinct

We generated monoclonal antibodies against the human Flt3 receptor and used them to study the characteristics of normal human bone marrow cells resolved based on Flt3 expression. Human CD34+ or CD34+lin- marrow cells were sorted into two populations: cells expressing high levels of Flt3 receptor (Flt3high) and cells with little or no expression of Flt3 receptor (Flt3low). Flt3 receptor was detected on a subset of CD34+CD38- marrow cells, as well as on CD34+CD19+ B lymphoid progenitors and CD34+CD14+CD64+ monocytic precursors. Flt3 receptor was also present on more mature CD34-CD14+ monocytes. In colony-forming assays, Flt3high cells gave rise mainly to colony-forming unit-granulocyte-macrophage (CFU-GM) colonies, whereas Flt3low cells produced mostly burst-forming unit-erythroid colonies. There was no difference in the number of multilineage CFU-Mix colonies between the two cell fractions. Cell cycle analysis showed that a large number of the Flt3low cells were in the G0 phase of the cell cycle, whereas Flt3high cells were predominantly in G1. Cell numbers in the suspension cultures initiated with Flt3high cells were maintained in the presence of Flt3 ligand (FL) alone, and increased in response to FL plus kit ligand (KL). In contrast, cell numbers in the suspension cultures started with Flt3low cells did not increase in the presence of FL, or FL plus KL. Upregulation of Flt3 receptor on Flt3low cells was not detected during suspension culture. CD14+ monocytes were the major cell type generated from CD34+lin-Flt3high cells in liquid suspension culture, whereas cells generated from CD34+lin-Flt3low cells were mainly CD71+GlycA+ erythroid cells. These results show clear functional differences between CD34+Flt3high and CD34+Flt3low cells and may have implications concerning the in vitro expansion of human hematopoietic progenitor cells.     

Solar ponds

This report provides the background to, and the current status of, solar ponds as proven viable large-area collectors capable of providing both low-cost thermal energy and mechanical or electrical energy using state-of-the-art low-temperature turbo-generators.After a short background statement giving the history and motivation to create a viable large-area collector with built-in storage, the basic theory of salt-gradient solar ponds is sketched. (More detailed-theory is available from the given references, particularly two recently published handbooks.) NaCl and MgCl₂ are two common and low-cost salts suitable for solar ponds. A number of problems such as the adverse effect of wind, leakage, fouling—and their solutions—are indicated as are some fundamental constraints (Section 8) that limit the sites suitable for solar ponds. Practical details include how ponds are built and filled and how the heat is extracted. Section 7 presents a condensed account of solar pond experience in a number of countries.Practical operating temperatures of 90°C are obtained with collection efficiencies usually between 15 and 25 per cent: this permits a number of practical applications as discused in Section 10, i.e. heating and cooling, power production and desalination.Realistic pond cost figures indicate thermal energy costs equivalent to US$41 per ton of fuel for a sunny climate (using a conservative 11.7 per cent annual charage on capital): such low-cost calories permit thermodynamic conversion to power: although the conversion efficiency is low, the solar pond power station (SPPS) is viable in many cases. Bus-bar power costs, for a sunny climate, vary from a high of US13.5 cents/kWh—using present technology—to a low 5.3 cents in sizes of 20 GWhr(e) per annum or larger.A 150-kW SPPS has already been built and successfully operated in Israel since December 1979 and a 5000-kW unit is due for completion in the next 2 yr.The ability of a solar pond to store heat even from summer to winter greatly increases its usefulness in almost all applications: for power production, the SPPS can—like a hydro-electric plant, provide peaks of power, on demand—far in excess of the pond mean capacity. The estimate that SPPS costs flatten out at 20–40 MW is of interest to developing countries that could install generating capacity in relatively small steps as demand grows.     

Solar ponds—Corrections

Variations in the average monthly, seasonal and daily patterns of total radiation, relative humidity, temperature and sunshine duration in Ibadan have been presented. Various empirical models relating solar radiation to the basic climatological parameters such as relative humidity, sunshine hours, temperature as well as geographical declination, latitude and altitude factors were investigated from the viewpoint of obtaining appropriate empirical formulae to determine solar radiation from such common parameters. The average monthly total radiation is shown to be predicted with reasonable accuracy by a couple of empirical formulae with the best result obtained from a newly proposed formula. The new formula is shown to give also good agreement when applied to the analysis of annual daily insolation data on a seasonal basis. Finally, the proposed formula predicts a linear relationship between the daily diffuse radiation and the daily total radiation in line with the Liu and Jordan model but with the fiffuse component generally higher in qualitative agreement with observations in the tropics.     

Immunosenescence in Aging-Related Vascular Dysfunction

The immunosenescence-related disproportion in T lymphocytes may have important consequences for endothelial dysfunction, which is a key event in vascular aging. The study was designed to assess the prognostic values of the inflammatory-immune profile to better predict and prevent vascular diseases associated with old age. Eighty individuals aged 70.9 ± 5.3 years were allocated to a low- (LGI) or high-grade inflammation (HGI) group based on CRP (<3 or ≥3 mg/L) as a conventional risk marker of cardiovascular diseases. Significant changes in inflammatory and endothelium-specific variables IL-1β, IL-6, TNFα, oxLDL, H₂O₂, NO, 3-nitrotyrosine, and endothelial progenitor cells (OR 7.61, 95% CI 2.56–29.05, p < 0.0001), confirmed their interplay in vascular inflammation. The flow-cytometry analysis demonstrated a high disproportion in T lymphocytes CD4⁺ and CD8⁺ between LGI and HGI groups. CRP was <3 mg/mL for the CD4/CD8 ratio within the reference values ≥ 1 or ≤2.5, unlike for the CD4/CD8 ratio < 1 and >2.5. The odds ratios for the distribution of CD4⁺ (OR 5.98, 95% CI 0.001–0.008, p < 0.001), CD8⁺ (OR 0.23, 95% CI 0.08–0.59, p < 0.01), and CD8CD45RO⁺ T naïve cells (OR 0.27, 95% CI 0.097–0.695, p < 0.01) and CD4/CD8 (OR 5.69, 95% CI 2.07–17.32, p < 0.001) indicated a potential diagnostic value of T lymphocytes for clinical prognosis in aging-related vascular dysfunction.