Improved methods for evaluating the molar mass distributions of cellulose in kraft pulp

Multi‐angle laser light scattering (MALLS) was used to characterize birch kraft pulps with respect to their absolute molecular mass distributions (MMDs). The pulps were dissolved in lithium chloride/N,N‐dimethylacetamide and separated by size exclusion chromatography (SEC). The weight‐average and number‐average molecular masses of the cellulose fractions of the pulps obtained from the absolute MALLS measurements were compared with the molar masses obtained by direct‐standard‐calibration relative pullulan standards. Discrepancies between the two detection methods were found, and two ways of correlating the relative pullulan molar masses to the absolute molar masses were examined. In the first method, the correlation was made over a large range of molecular masses. The second method correlated the molecular masses of the standards to the molecular masses of samples by the calculation of fictitious, cellulose‐equivalent molar masses of the standards. With the preferred second method, a more correct MMD of kraft pulp samples could, therefore, be obtained from an SEC system calibrated with narrow standards. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1170–1179, 2003     

Time for more active lipid-lowering treatment of patients with diabetes. Negative effect of hyperlipidemia on beta-cells is a neglected field

Type 2 diabetes mellitus is a common metabolic disorder whose prevalence is increasing in the western world. The ravaging complications of the disease constitute a major cause of hospitalisation and cardiovascular morbidity, and despite intensive research the pathogenic mechanism remain unknown. The article summarises some recent advances in the field of islet beta-cell dysfunction caused by hyperlipidaemia in the diabetic state, which results in perturbed insulin secretory capacity and overt glucose intolerance. In contrast to hyperglycaemia, the detrimental effects of hyperlipidaemia have been a relatively neglected area of diabetes research. However, the direct inhibitory effects of long-term hyperlipidaemia on beta-cell function, 'lipotoxicity,' should form the basis of a more active approach to lipid screening and pharmacological treatment of hyperlipidaemia in diabetes patients. Intervention in the leptin pathway may prove beneficial in future treatment strategies.     

Direct measurement of the spectral transfer function of a laser based anemometer

The effect of a continuous-wave (cw) laser based anemometer's probe volume on the measurement of wind turbulence is studied in this paper. Wind speed time series acquired by both a remote sensing cw laser anemometer, whose line-of-sight was aligned with the wind direction, and by a reference sensor (sonic anemometer) located in the same direction, were used. The spectral transfer function, which describes the attenuation of the power spectral density of the wind speed turbulence, was calculated and found to be in good agreement with the theoretical exponential function, which is based on the properties of the probe volume of a focused Gaussian laser beam. Parameters such as fluctuations of the wind direction, as well as the overestimation of the laser Doppler spectrum threshold, were found to affect the calculation of the spectral transfer function by introducing high frequency noise.     

Hydrogenolysis of Hydroxymatairesinol Over Carbon-Supported Palladium Catalysts

The natural lignan hydroxymatairesinol was hydrogenolysed to a potential anticarcinogenic substance matairesinol over different carbon-supported palladium catalysts. The reaction was conducted in 2-propanol at 70 °C under hydrogen flow in a stirred glass reactor. The catalysts were characterised by N₂-physisorption, CO pulse chemisorption and pH measurement of aqueous catalyst slurries. The most active catalyst (Degussa-Hüls) gave yields of matairesinol over 90% in 4 h. It was concluded that the acidity of the catalyst had a profound influence on the reaction rate.     

Regulation of insulinoma cell proliferation and insulin accumulation by peptides and second messengers

The regulation of clonal rat insulinoma (RINm5F) cell proliferation and hormone accumulation was investigated with the aim of identifying putative compounds capable of inducing differentiation, i.e. decreased growth and increased insulin accumulation, by the tumor cells. In particular, interest was focused on the role of a number of peptides as well as pharmacological probes modulating various signal transduction systems and which have been shown to regulate normal beta-cell proliferation and insulin accumulation. Growth hormone stimulated insulin accumulation and inhibited DNA synthesis, whereas galanin and insulin-like growth factor I caused a moderate suppression of insulin accumulation but did not affect proliferation, while epidermal growth factor, transforming growth factor beta, platelet-derived growth factor, acidic and basic fibroblast growth factor, bradykinin and somatostatin were virtually inactive on all parameters tested. Exogenous prostaglandins E2 and F1 alpha were inactive, while the cycloxygenase inhibitor indomethacin slightly suppressed insulin accumulation. The cytokine IL-1 beta caused a significant decrease in both beta-cell mitogenesis and insulin accumulation, effects that were mediated through nitric oxide generation. The vitamin A derivative retinyl acetate slightly inhibited serum-stimulated DNA synthesis, but did not affect insulin accumulation. The vitamin E alpha-tocopherol significantly enhanced insulin release but did not affect mitogenesis. By contrast, gamma-tocopherol was inactive on both these parameters. The alpha-adrenergic agonist clonidine evoked a slight inhibition of serum-stimulated DNA synthesis, without influencing insulin accumulation, whereas phenylephrine did not affect any of these parameters. Carbamylcholine increased insulin accumulation, but not cell proliferation, whereas the adenylyl cyclase activator forskolin suppressed mitogenesis but did not affect insulin accumulation. Inhibition of protein kinase C with staurosporine or prolonged treatment with phorbol ester suppressed DNA synthesis, as did the tyrosine kinase inhibitor genistein. Stimulating Ca2+ influx by closing ATP-dependent K+ channels with glibenclamide enhanced DNA synthesis, while opening of these channels with diazoxide suppressed cell growth. Conversely, preventing Ca2+ influx by the Ca2+ channel antagonist D-600, chelating intracellular Ca2+ by fura-2 AM or inhibiting the Ca2+/calmodulin-dependent protein kinase by calmidazol resulted in a decreased DNA synthesis. On the other hand, uncontrolled influx or mobilization of Ca2+ by ionomycin or thapsigargin resulted in an arrested DNA synthesis. The present paper shows that RINm5F insulinoma cell proliferation and insulin accumulation can be modulated by various peptidergic and pharmacological agents regulating certain signal transduction pathways. However, mitogenesis in the insulinoma cells seemingly is controlled in a vastly different manner in comparison to that in normal beta-cells. The most spectacular finding in this screening study, i.e. that growth hormone, contrarily to its effect on normal beta-cells, suppresses insulinoma cell growth, merits further elucidation of the underlying mechanisms. Possibly the hormone might become of utility in a clinical setting in the treatment of patients with insulin-producing tumors.     

Inhibition of phosphatases and increased Ca2+ channel activity by inositol hexakisphosphate

Inositol hexakisphosphate (InsP6), the dominant inositol phosphate in insulin-secreting pancreatic beta cells, inhibited the serine-threonine protein phosphatases type 1, type 2A, and type 3 in a concentration-dependent manner. The activity of voltage-gated L-type calcium channels is increased in cells treated with inhibitors of serine-threonine protein phosphatases. Thus, the increased calcium channel activity obtained in the presence of InsP6 might result from the inhibition of phosphatase activity. Glucose elicited a transient increase in InsP6 concentration, which indicates that this inositol polyphosphate may modulate calcium influx over the plasma membrane and serve as a signal in the pancreatic beta cell stimulus-secretion coupling.     

Binding of properdin to solid-phase immune complexes: critical role of the classical activation pathway of complement

OBJECTIVE: Our objectives were to assess the clinical and microbiological aspects of septic osteoarthritis in children admitted to our center from 1987 until July 1997 and to determine the sensitivity of ultrasound in this age group. PATIENTS AND METHODS: The medical records of 36 children diagnosed as having septic osteoarthritis of the hip were reviewed retrospectively. The diagnosis had been based on clinical criteria, along with synovectomy and drainage of purulent material from the affected joint. An X-ray and/or ultrasound had been performed when the diagnosis was suspected. RESULTS: Nineteen children were diagnosed during the neonatal period, 8 between the ages of 1 and 12 months and 9 older than one year of age. Mean age at diagnosis was 16.8 +/- 6.2 months (median 29 days, range 6 days to 13 years). The hip was involved in 32 children, the ankle in 3 and the elbow in 1. A microbiological diagnosis was achieved in 22 cases (61%) by culture from blood, CSF, and/or synovial fluid. The most common isolates were Gram positive cocci (S. aureus in 9 cases and coagulase negative Staphylococcus in 3). The diagnostic value of the X-rays was very low (18%). The ultrasound was initially considered abnormal in 64.5% of the patients, with a lower sensitivity in the neonatal period. After a mean follow-up period of 36 months, the outcome was good in 86% of the cases, although three children continue with sequelae. Two preterm infants died due to sepsis associated with the osteoarthritis. CONCLUSIONS: At the time of diagnosis of septic arthritis of the hip, the ultrasound is frequently normal. Due to the poor outcome when there is a delay in surgery, we suggest immediate synovectomy and drainage when there is clinical suspicion of septic arthritis despite an apparently normal ultrasound.     

Acrylamide in home-prepared roasted potatoes

Potato is one of the world's most widely grown tuber crop, in which starch is the predominant form of carbohydrates. Potatoes can be prepared in many ways: boiled, fried or roasted. Frying and roasting potatoes at high temperatures result in an appetizing crust, but at the same time acrylamide can form. In this study, the concentrations of the acrylamide precursors, asparagine and sugars, were determined in five different Swedish-grown potato varieties, together with the acrylamide content after typical home-cooking procedures; oven-roasting of potato wedges and pan-frying of cubes of boiled potatoes. Pan-frying of boiled potato cubes resulted in higher levels of acrylamide (530-1100 microg/kg) than in the wedges (140-250 microg/kg). Blanching combined with a shorter roasting time was shown to be an efficient way of reducing the acrylamide content in roasted potato wedges, especially in the experiments performed after long-term storage, where the acrylamide content was reduced from 110-260 to 50-140 microg/kg. No correlation was found between precursor content and acrylamide content, and this finding emphasizes the need for further studies on factors affecting acrylamide formation, for example, the availability of precursors at the surface during cooking.     

Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N‐dimethylacetamide

A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N‐dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high‐molecular‐mass material and increased the proportion of the low‐molecular‐mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a κ number of around 50. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 424–431, 2004