New operational matrices for solving fractional differential equations on the half-line.

In this paper, the fractional-order generalized Laguerre operational matrices (FGLOM) of fractional derivatives and fractional integration are derived. These operational matrices are used together with spectral tau method for solving linear fractional differential equations (FDEs) of order ν (0 < ν < 1) on the half line. An upper bound of the absolute errors is obtained for the approximate and exact solutions. Fractional-order generalized Laguerre pseudo-spectral approximation is investigated for solving nonlinear initial value problem of fractional order ν. The extension of the fractional-order generalized Laguerre pseudo-spectral method is given to solve systems of FDEs. We present the advantages of using the spectral schemes based on fractional-order generalized Laguerre functions and compare them with other methods. Several numerical examples are implemented for FDEs and systems of FDEs including linear and nonlinear terms. We demonstrate the high accuracy and the efficiency of the proposed techniques.

Cost-effectiveness of ceftriaxone in the treatment of community-acquired pneumonia in adult hospital patients. A pharmaco-economic study based on a meta-analysis.

OBJECTIVES: A retrospective analysis was conducted to assess the cost-effectiveness of four intravenous antibiotic treatment regimens in the treatment of severe community-acquired pneumonia (CAP) in adults in a private hospital setting. The study compared some third-generation cephalosporin regimens with a second-generation cephalosporin and an amoxicillin/clavulanic acid (co-amoxiclav) regimen to investigate published South African treatment guidelines from a pharmaco-economic point of view. METHOD: A pharmaco-economic model of local costs, from a payer perspective, was based on the results of a meta-analysis of clinical papers from peer-reviewed journals. The study compared intravenous (i.v.) ceftriaxone (2 g once daily), cefotaxime (i.v. 2 g 3 times a day), cefuroxime (i.v. 750 mg 3 times a day, followed by 500 mg orally 3 times a day) and amoxicillin/clavulanic acid (1.2 g intravenously 3 times a day, followed by 625 mg orally 3 times a day) [corrected]. RESULTS: An analysis of the odds ratios (ORs) of all two-way comparisons indicated that ceftriaxone ensured significantly higher probabilities of successful outcomes than the other antibiotic treatment regimens (ORs in the order of two were indicated). The pharmaco-economic results suggested that the ceftriaxone treatment regimen was the most cost-effective in the hospital treatment of CAP in adult patients. These results proved to be robust across sensitivity analyses for success rates and treatment days. A sensitivity analysis testing the assumption that patients could be discharged once the oral treatment was initiated indicated that the amoxicillin/clavulanic acid and cefuroxime treatment arms were more cost-effective. The clinical validity of such an assumption is questionable. CONCLUSION: Despite the conservative approach followed in terms of ceftriaxone data, both the clinical results and cost-effectiveness supported the use of ceftriaxone in the treatment of CAP in adults in the hospital setting.

Blunted erythropoietin response to anaemia in tuberculosis.

The precise cause of the anaemia that is commonly associated with severe pulmonary tuberculosis (PTB) has not been elucidated. The role of erythropoietin (Epo), the central hormone regulating red cell formation, still awaits clarification. We therefore determined serum Epo levels in patients with PTB; group 1, haemoglobin less than 110 g/L, group 2, haemoglobin greater than 110 g/L; group 3, controls, consisted of matched individuals with uncomplicated iron deficiency; group 4, healthy volunteers. Peripheral blood monocytes were obtained from patients with PTB and the controls, cultured, and the supernatant fluid (SNF) harvested. Tumour necrosis factor alpha (TNF alpha) levels were determined in the SNF, which were then added in various dilutions to a hepatocellular carcinoma cell line (HepG2) capable of regulated EPO synthesis in vitro. The influence of this cytokine was defined by the addition of specific neutralising anti-TNF alpha antibodies in this assay system. Patients in group 1 had significantly lower Epo levels (54 + 11 mU/mL) compared with those in group 3 (142 +/- 41 mU/mL) (p < 0.01). Monocyte supernatants from patients in the anaemic PTB group had markedly elevated TNF alpha levels and significantly suppressed Epo output by HepG2 cells in vitro (p < 0.01). This inhibition was consistently abrogated by anti-TNF alpha antibodies. Serum Epo levels were inappropriately low in untreated PTB patients when compared with corresponding haemoglobin levels in iron deficient controls. This blunted response could be ascribed to release of TNF alpha or other cytokines by activated monocytes.

Characterisation of functional domains within the mouse erythropoietin 3' enhancer conveying oxygen-regulated responses in different cell lines.

We have analysed sequences within the mouse erythropoietin enhancer which are required for oxygen regulated operation in the erythropoietin producing cell line, HepG2, and in two non-erythropoietin producing cell lines; the lung fibroblastoid cell line a23, and mouse erythroleukaemia (MEL) cells. At least three critical sites were demonstrated within a 96 nucleotide sequence. Oxygen regulated operation was dependent on sites within the first 26 nucleotides. Sequences lying 3' to this region modulated enhancer function but did not themselves convey oxygen regulated operation. In HepG2 cells these 3' sequences co-operated to permit operation of the inducible element at a distance from a promoter, but in MEL cells 3' sequences repressed activity of the inducible element. Though operation of this 3' sequence differed according to the cell type, oxygen regulated operation was dependent on the same two critical sites in the 5' region in both erythropoietin producing and non-erythropoietin producing cells. These findings support the existence of a widespread oxygen sensing system in mammalian cells which is similar to that operating in specific cells to regulate erythropoietin production, and they indicate that the system activates factors with similar DNA sequence specificity in different cells.

Peripheral blood mononuclear cells from patients with chronic renal failure release factors which suppress erythropoietin secretion in vitro.

Decreased production of erythropoietin (Epo) as a result of reduced renal mass is considered the main factor underlying the anaemia that is invariably associated with chronic renal failure (CRF). Other mechanisms such as accumulation of inhibitors of Epo also contribute. In this study we show that supernatant from peripheral blood mononuclear cells (PBMC) cultured from patients with CRF inhibits Epo release by Hep G2 cells in vitro. Ten patients (5 male) with CRF (mean age 42 years, range 25-60) were studied. Five were approaching end-stage renal failure and five were maintained on haemodialysis (HD). Ten apparently healthy volunteers were used as controls. Full blood counts and serum Epo (RIA) levels were determined and adherent PBMC were cultured for 48 h with and without LPS. There was a significant rise in TNF-alpha and IL1-beta levels measured in monocyte supernatant (MS) from patients and controls after LPS stimulation (P < 0.05) and in IL-1 alpha levels in patients (P < 0.05). IL-1 beta levels were higher in patients compared to controls both before and after stimulation with LPS (P < 0.05). Hep G2 cells were cultured in 5% CO2 and 20% O2 and incubated with MS from patients and controls for 24 h. Hep G2 harvest fluids were then analysed for Epo levels, which were expressed as a function of total cell protein (mU/mg). Epo production was inhibited by MS from patients compared to controls both before and after stimulation with LPS (P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)