Increased levels of multiple forms of dihydrofolate reductase in peripheral blood leucocytes of cancer patients receiving haematopoietic colony-stimulating factors: interim analysis

The precise mechanism whereby granulocytes proliferate when haematopoietic colony stimulating factors (CSFs) are used in neutropenic cancer patients is poorly understood. The purpose of this study was to investigate whether these cytokines bring about leucocyte proliferation by increasing the levels of multiple forms of dihydrofolate reductase (DHFR). Blood samples were collected from 36 cancer patients (25 males and 11 females) with chemotherapy-induced neutropenia. One sample of blood from each patient was obtained before therapy either with CSF, such as granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) or with placebo, and another one at the time of resolution of neutropenia. Peripheral blood leucocytes in these blood samples were counted, separated and lysed. From lysates, cytoplasmic samples were prepared and analyzed for active DHFR by a methotrexate-binding assay and for total immunoreactive DHFR by an enzyme linked immunosorbent assay. The increase in total leucocyte count (TLC) was most prominent (P < 0.005) in the CSF group and less so (P < 0.05) in the placebo group. The mean +/- SD concentration values of active DHFR before and after stimulation with GM-CSF found were to be 0.34 +/- 0.4 ng/mg protein and 0.99 +/- 0.82 ng/mg protein, respectively, and in the group treated with G-CSF, 0.24 +/- 0.32 ng/mg protein and 1.18 +/- 2.4 ng/mg protein, respectively. This increase in active DHFR after stimulation with CSF was statistically significant (P < 0.05). Similarly, concentration values of immunoreactive but nonfunctional form of DHFR (IRE) were 110 +/- 97 ng/mg protein and 605 +/- 475 ng/mg protein before and after stimulation with GM-CSF, and 115 +/- 165 ng/mg protein and 1,054 +/- 1,095 ng/ mg protein before and after stimulation with G-CSF. This increase in concentration of IRE after stimulation with GM-CSF or G-CSF was statistically significant (P < 0.005). In the control group, there was an increase in the concentration of both active DHFR and IRE after treatment with placebo. However, this was not statistically significant. Resolution of neutropenia was quicker in the groups treated with CSF compared to the control group. Results of this study indicate that colony stimulating factors (G-CSF and GM-CSF) induce white cell proliferation by increasing the levels of multiple forms of DHFR.     

The extraction of chromium(VI) from sulphuric acid solutions by 4-(5-nonyl)pyridine and its separation from fission products

4-(5-Nonyl)pyridine, a new liquid anion exchanger, has been studied for the extraction of chromium(VI) from sulphuric acid solutions. The optimal acidity is 0.1–1 M, depending on the concentration of chromium. Common anions have little effect on extraction in concentrations up to 0.1 M. Reducing agents such as ascorbic acid and thiosulphate prevent extraction at concentrations above 0.1 M. Separation of chromium(VI) from fission products was achieved.     

Two new rearranged taxoids from Taxus wallichiana ZUCC

Two new rearranged taxane diterpenoids, 5alpha,7beta,10beta,13alpha-tetrahydroxy-2alpha,9alpha,15-triacetoxy-11(15-->1)-abeo-taxa-4(20), 11-diene (1) and 5alpha,9alpha,10beta,13alpha-tetraacetoxy-15-hydroxy-11(15-->1)-abeo-taxa-4(20), 11-diene (2) have been isolated from the barks of Taxus wallichiana. The structures of these compounds have been confirmed by modern spectroscopic techniques.     

Monoterpene glycosides from Indigofera hetrantha

Monoterpene glycosides have been isolated from the ethyl acetate soluble fraction of Indigofera hetrantha and their structures assigned to be 3,7-dimethyl-2(E),6-octadien-5-one-1-O-beta-D-6-O-acetylglucopyranoside (1) and 3,7-dimethyl-2(E), 6-octadien-5-one-1-O-[-beta-D-6'-O-acetylglucopyra-nosyl (1' --> 6')-beta-D-glucopyranoside] (2), on the basis of spectroscopic analysis including 1D and 2D NMR techniques. Compounds 1 and 2 displayed moderate inhibitory potential against the enzyme lipoxygenase.     

Electrochemical modulation of sickle cell haemoglobin polymerisation

Sickle cell haemoglobin (HbS) differs from normal haemoglobin by a single amino acid in its beta chain. This amino acid replacement, from glutamic acid to valine, causes polymerisation of proteins into defined long insoluble fibres with a typical diameter of 21.5 nm. The polymerisation is triggered by the formation of deoxyhaemoglobin (deoxyHb) from oxyhaemoglobin (oxyHb) in low oxygen partial pressures, which results in a conformational change in the secondary structure of the protein. We describe an electrochemical method to modulate the oxygen concentration in an optically transparent thin layer cell to produce deoxyhaemoglobin whilst monitoring the extent of polymerisation using turbidity measurements. The oxygen is depleted in the vicinity of the electrode and triggers the polymerisation. The kinetics of polymerisation were investigated using a model for fibrillogenesis describing a two-step process of nucleation followed by elongation. Rate constants describing the nucleation and growth at monomer concentration of 300 mg cm(-3) (4.65 x 10(-3) M) were determined to be 9.45 (+/-0.08) x 10(-6) s(-1) and 1.22 (+/-0.03) x 10(-3) s(-1) respectively, showing that nucleation was far slower than the growth. A similar difference between the rate constants for the nucleation (2.99 (+/-0.4) x 10(-8) s(-1)) and growth (1.08 (+/-0.2) x 10(-3) s(-1)) was seen at monomer concentration of 50 mg cm(-3) (7.75 x 10(-4) M). These results show that nucleation was monomer concentration dependent; however growth was largely independent of monomer concentration. In this study we present a methodology that may be used as a screening method for substances that effect the fibre nucleation and or growth that could be valuable to the pharmaceutical industry for treating sickle cell disease.     

Studies on the chemical constituents of Phyllanthus emblica

Phytochemical investigations on Phyllanthus emblica have resulted in the isolation of the two new flavonoids, kaempferol-3-O-alpha-L-(6'-methyl)-rhamnopyranoside (1) and kaempferol-3-O-alpha-L-(6'-ethyl)-rhamnopyranoside (2). Their structures were determined on the basis of extensive spectroscopic studies including 2D-NMR experiments.     

Kinetics studies on triacontanyl palmitate: a urease inhibitor

The mechanism of inhibition of jack bean and Bacillus pasteurii ureases was investigated by triacontanyl palmitate (1) which is a long-chain fatty ester and has been isolated from Symplocos racemosa Roxb. Lineweaver-Burk, Dixon plots, and their secondary replots showed that 1 is a non-competitive inhibitor of these enzymes. K(i) values were found to be 60.03 +/- 1.72 and 88.23 +/- 0.31 microM against jack bean and B. pasteurii ureases, respectively.     

Swarnalin and cis-swarnalin, two new tetrahydrofuran derivatives with free radical scavenging activity, from the aerial parts of Cuscuta reflexa

The reversed-phase HPLC analysis of a methanol extract of the aerial parts of Cuscuta reflexa afforded a non-separable mixture (55 : 45) of two novel tetrahydrofuran derivatives, named swarnalin (1) and cis-swarnalin (2), and a known coumarin, 5,6,7-trimethoxycoumarin (3). The structures of the compounds were elucidated unequivocally by UV, HRFABMS and a series of 1D and 2D NMR analyses. The mixture of 1 and 2 showed significant free radical scavenging activity in the DPPH assay and the RC50 value was found to be 3.80 x 10(-4) mg mL(-1) for the mixture, compared to 2.88 x 10(-5) mg mL(-1) for the positive control, quercetin.     

Simpler spectrophotometric assay of paracetamol in tablets and urine samples

A very fast, economical and simpler direct spectrophotometric method was investigated for paracetamol (PC) determination in aqueous medium without using any chemical reagents. The method is based on the photo-absorption of the analyte at 243 nm after dissolution in water. The change in structure of PC after addition of water was studied by comparing the corresponding FTIR spectra. Optimization studies were conducted by using a 5 microg ml(-1) standard solution of the analyte. Various parameters studied include, time for stability and measurement of spectra, effect of HCl, NaOH, CH(3)COOH and NH(3) for change in absorbance and shift in spectra, interference by some analgesic drugs and some polar solvents and temperature effect. After optimization, Beer's law was obeyed in the range of 0.3-20 microg ml(-1) PC solution with a correlation coefficient of 0.9999 and detection limit of 0.1 microg ml(-1). The newly developed method was successfully applied for PC determination in some locally available tablets and urine samples. The proposed method is very useful for quick analysis of various types of solid and liquid samples containing PC.