The relation between cholesterol and haemorrhagic or ischaemic stroke in the Renfrew/Paisley study

Studies have found little association between cholesterol and overall stroke risk, but this could be attributable to different relations for haemorrhagic and ischaemic stroke. Stroke mortality data from prospective studies cannot usually be divided into stroke subtypes. We have therefore analysed stroke based on hospital admissions, obtained by computerised linkage with acute hospital discharges in Scotland for a large prospective cohort study

Studies on the Role of Urinary Macromolecules in Urolithiasis: Review of Methodologies and a Proposal for a Standard Reference Crystallization System

In this study, urine from a calcium oxalate kidney stone former was ultrafiltered (10 kD cut-off). Crystallization was induced in the ultrafiltrate and retentate fractions as well as in a sample of the whole urine. The progress of crystallization was monitored by Coulter Counter and flow cytometry techniques. (The latter has not been used in studies of the role of urinary macro-molecules in urolithiasis). Deposited crystals were examined by scanning electron microscopy. Results indicated that urinary macromolecules in this subject are inhibitors of nucleation and aggregation. These results agree with the findings of some workers but disagree with those of others. Indeed, studies on the role played by urinary macromolecules in promoting or inhibiting urolithiasis have failed to produce consistent findings. Examination of the literature reveals that a wide variety of experimental techniques and crystallization systems have been used in these studies and that this might be the cause of the inconsistencies. Based on reported experiences and those of the present study, a standard reference crystallization system is proposed. The key elements of this system involve the use of real urine, ultrafiltration, continuous crystallizer equipment, Coulter Counter procedures and scanning electron microscopy

Influence of Ageing, pH and Various Additives on Crystal Formation in Artificial Urine

In order to investigate the effect of various factors on urinary crystallization processes, a series of five experiments was carried out using an artificial urine (AU) in a rotary evaporator. The influence of ageing, pH and organic, inorganic and potential inhibitory additives formed the basis of the study. Precipitates were characterized by X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray analysis. In the ageing experiment, AU aliquots, adjusted to various pH values, were allowed to stand for several days and were not evaporated. Calcium oxalate monohydrate (COM) was formed at low pH, while whitlockite, apatite and struvite occurred at pH \u3e 7. In the second experiment, AU aliquots at various pH values, were evaporated. Similar results to those of series 1 were recorded but, in addition, calcium oxalate trihydrate (COT) precipitated in the pH range 3 to 6.5 and brushite at pH \u3e 5.5. In series 3, uric acid, creatinine and urea were included in AU aliquots (pH 5.5) which were subjected to evaporation. Uric acid promoted the formation of uric acid dihydrate; however, when present with creatinine, dihydrate formation was inhibited. Urea appeared to inhibit precipitation. In the fourth experiment, MgO, methylene blue and chondroitin sulphate A were independently included in the AU (pH 5.5). Precipitates of calcium oxalate mono-, di- and trihydrates were obtained. In the final experiment fluoride aliquots of variable concentrations were included in the AU (pH 5.5 and 6.5). COT crystals of superior quality to those observed in control solutions were obtained

The crystal and molecular structure of the bis(4-N, N1-dimethylaminopyridine) solvate of disalicylicacidatobis(nitrotodioxouranium)(VI)

The structure of the title compound [(C7H4NO8U)(C7H11N2)]2 has been determined by Patterson and Fourier methods from single crystal X-ray diffraction data collected on a four-circle diffractometer. Full-matrix least-squares refinement yielded a final conventional R of 0.041 for 2189 reflections. The complex crystallizes in the space group P with a = 11.004(5), b = 9.981(5), c = 9.928(5) Å, α = 119.6(3), β = 107.7(3), γ = 81.9(3)°, Dm = 2.17, Dc = 2.173g cm−3. The structure is dimeric. The uranium atoms are eight-coordinate and are bridged via centrosymmetrically related carboxylic oxygen atoms. The nitrate group is bidentate and the average U---O (ligand) distance is 2.463 Å. Hydrogen bonding of the type N---HO links two dimethyl-aminopyridine molecules to the dimer

The structure of aliphatic amine adducts of uranyl acetylacetonate. III. Dioxobis(2,4-pentanedionato)mono (2-N-isopropylaminopentan-4-one)uranium(VI)

Introduction: In two earlier structural determinations of compounds of this type we have shown that the conformation of the adduct moiety is dependent on the formation of intramolecular N-H...0 hydrogen bonds (part I: Haigh, Nassimbeni, Pauptit, Rodgers & Sheldrick, 1976; part II: Nassimbeni, Orpen, Pauptit, Rodgers & Haigh, 1977). We have carried out the present analysis to study the conformational effects on the ligand brought about by the steric influence of an isopropyl substituent at N

Effect of Urinary Macromolecules and Chondroitin Sulphate on Calcium Oxalate Crystallization in Urine

After filtration and ultrafiltration (10 kD) of 24 hour urine specimens from 12 healthy male subjects, calcium oxalate crystallization was induced in the filtered (FILTD) and ultrafiltered (UF) fractions by administration of a sodium oxalate load. In addition crystallization was also induced in UF fractions to which physiological quantities of chondroitin sulphate (CHON) had been added (UF + CHON). The rate of calcium oxalate crystallization was determined by measuring the rate at which turbidity increased. Crystal numbers and sizes were measured with a Malvern particle size analyzer and by scanning electron microscopy. Crystallization rates, crystal numbers and crystal sizes were generally lower in UF fractions than in FIL TD fractions suggesting that urinary macromolecules are promoters of calcium oxalate crystallization. No increase in crystallization rate, crystal numbers or sizes occurred when chondroitin sulphate was added to UF fractions, indicating that the promoter activity of urinary macromolecules is not due to this particular glycosaminoglycan. On the contrary, crystallization rates were qualitatively lower in UF + CHON fractions than in UF fractions alone, suggesting a possible inhibitory role for chondroitin sulphate in real urine. Scanning electron microscopy revealed that while aggregates were present in UF and FILTD fractions, they were absent in UF + CHON fractions. This observation indicates that chondroitin sulphate might be an inhibitor of calcium oxalate crystal aggregation in real urine

The young massive stellar cluster associated to RCW121

We report NIR broad and narrow band photometric observations in the direction of the IRAS17149-3916 source that reveal the presence of a young cluster of massive stars embedded in an HII region coincident with RCW121. These observations, together with published radio data, MSX and Spitzer images were used to determine some of the physical parameters of the region. We found 96 cluster member candidates in an area of about 1.5 x 2.0 square arcmin, 30% of them showing excess emission in the NIR. IRS 1, the strongest source in the cluster with an estimated spectral type of O5V-O6V ZAMS based on the color-magnitude diagram, is probably the main ionizing source of the HII region detected at radio wavelengths. Using the integrated Brgamma and the 5 GHz flux densities, we derived a mean visual extinction AV=5.49 magnitudes. From the observed size of the Brgamma extended emission, we calculated the emission measure E and the electron density ne, characteristic of compact HII regions.Comment: 18 pages, 8 figures, accepted for publication on AJ (February/2006

Stretched exponentials and power laws in granular avalanching

We introduce a model for granular avalanching which exhibits both stretched exponential and power law avalanching over its parameter range. Two modes of transport are incorporated, a rolling layer consisting of individual particles and the overdamped, sliding motion of particle clusters. The crossover in behaviour observed in experiments on piles of rice is attributed to a change in the dominant mode of transport. We predict that power law avalanching will be observed whenever surface flow is dominated by clustered motion. Comment: 8 pages, more concise and some points clarified