Enzyme-Catalyzed oxidation of cholesterol in physically characterized water-in-oil microemulsions

The enzymatic conversion of cholesterol to cholestenone by cholesterol oxidase (Brevibacterium sp.)in reversed micelles in a system composed of AOT/isooctane/water/cholesterol has been examined. The catalytic activity of the enzyme was correlated with the physicochemical properties of water in water-in-oil (w/o) microemulsion systems. In a system consisting of 3 wt % AOT in isooctane, reversed micelles started to form as the [H(2)O]/[AOT] (e.g., the w(0)) ratio increased above 4-5. The formation of reversed micelles with a core of neat (bulk) water was verified from determinations of both the partial molar volume of water and the scissors vibration of water [with Fourier transform infrared (FTIR) spectroscopy] in the w/o microemulsion systems. A plot of enzyme activity vs. w(0) indicated that the hydration of enzyme molecules per se was not sufficient to give rise to catalytic activity. Instead, it appeared that the formation of an aqueous micellar core was necessary for full activation of the enzyme. Based on micelle size distribution analysis, it was estimated that about one micelle per one thousand contained an enzyme molecule. Since the apparent reaction rate could be markedly enhanced by increasing the enzyme/water ratio, we conclude that the number of enzyme-containing micelles was an important rate-limiting factor in the system.     

Perceived needs and satisfaction with care in people with multiple sclerosis: A two-year prospective study

Background  

Considering the costs of multiple sclerosis (MS), it is crucial that the health-related services supplied are in accordance with needs as they are perceived by people with MS (PwMS). Satisfaction with care is related to quality of care and can provide health care providers with the means for improvement. The aim was to explore the perceived needs and satisfaction with care amongst PwMS over a two-year period, also taking sex and disease severity into consideration.     

Platelet-derived growth factor-B and -C and active alpha-receptors in medulloblastoma cells

The malignant childhood brain tumor medulloblastoma belongs to the group of primitive neuroectodermal tumours (PNETs). Medulloblastomas are thought to arise from remnants of the transient external germinal layer in the cerebellum. Proliferation, differentiation, and motility of cells in the central nervous system are regulated by growth factors, e.g., platelet-derived growth factor (PDGF). Recently, it was shown that higher level of PDGF alpha-receptor expression is characteristic of metastatic medulloblastomas. We have investigated five medulloblastoma/PNET cell lines and found that the PDGF alpha-receptor is actively signalling in most of them, an activity most likely driven by endogenously produced PDGF-C. PDGF-C is normally present in cells of the developing external germinal layer and our results are consistent with the idea that medulloblastomas are derived from such cells undergoing early neuronal differentiation. Moreover, the expression of PDGF and its receptors was associated with neuronal characteristics, but not with high levels of c-myc expression in the medullablastoma cells.     

Efficient algorithms for quantitative trait loci mapping problems.

Rapid advances in molecular genetics push the need for efficient data analysis. Advanced algorithms are necessary for extracting all possible information from large experimental data sets. We present a general linear algebra framework for quantitative trait loci (QTL) mapping, using both linear regression and maximum likelihood estimation. The formulation simplifies future comparisons between and theoretical analyses of the methods. We show how the common structure of QTL analysis models can be used to improve the kernel algorithms, drastically reducing the computational effort while retaining the original analysis results. We have evaluated our new algorithms on data sets originating from two large F(2) populations of domestic animals. Using an updating approach, we show that 1-3 orders of magnitude reduction in computational demand can be achieved for matrix factorizations. For interval-mapping/composite-interval-mapping settings using a maximum likelihood model, we also show how to use the original EM algorithm instead of the ECM approximation, significantly improving the convergence and further reducing the computational time. The algorithmic improvements makes it feasible to perform analyses which have previously been deemed impractical or even impossible. For example, using the new algorithms, it is reasonable to perform permutation testing using exhaustive search on populations of 200 individuals using an epistatic two-QTL model.     

Science commentary: Why wine might be less harmful than beer and spirits

Objective: To analyse sick leave in women at risk of primary hyperparathyroidism before its diagnosis. Design: Case-control study nested within a screened cohort of postmenopausal women. Cases were women with hyperparathyroidism without prior knowledge of their disease and no traditional symptoms or complications. Controls were women from the screened population without hyperparathyroidism. Setting: Population based screening within a Swedish community. Subject: 48 case-control pairs of women aged 55-70 years. Main outcome measure: Sick leave during the 5 years before diagnosis. Results: Total duration of sickness benefits was longer in the cases than controls, and this discrepancy included sick leave on full time or half time and for periods of longer than a week. Cases had an increased risk of sick leave more than half of the investigated time compared with controls (odds ratio 12). Doctors’ certificates showed that the overrepresented sick leave in the cases related mainly to cardiovascular diseases. Conclusion: Asymptomatic mild primary hyperparathyroidism in postmenopausal women is accompanied by a previously unrecognised morbidity, which has consequences for clinical management of the disorder and its impact on the health economy.

Key messages

• Primary hyperparathyroidism mainly affects postmenopausal women, many of whom lack classic symptoms and complications of the disorder and are currently considered suitable for conservative follow up
• Postmenopausal women with asymptomatic primary hyperparathyroidism drew more sickness benefit than matched controls during the 5 years before the diagnosis
• Cardiovascular diseases were the main cause of sick leave
• The duration of sick leave was not correlated with age or serum calcium concentration
• Mild undiagnosed hyperparathyroidism in postmenopausal women is linked with previously unrecognised ill health of importance to the clinical and economic impact of the disorder

     

Immunohistology on Formol-Sublimate Fixed and Paraplast Embedded Kidney Tissue with Comparison to Formalin Fixation and to Pre-Embedding Immunofluorescent Staining

Many alternative methods for immunopathological evaluation of kidney tissue are now available. Immunofluorescent or immunoperoxidase staining of kidney can be performed after formalin fixation and paraffin embedding. This is also possible after fixation with formol-sublimate (Stieve's fluid) using the immunoperoxidase technique or by immunofluorescence after removal of mercury. Reduction of strong nonspecific fluorescence caused by the mercury fixative parallels the elimination of mercury as verified by X-ray microanalysis of the sections. Using a mouse model with injection of graded dilutions of antiglomerular basement membrane antibodies, immunofluorescent staining after Stieve fixation and embedding in Paraplast was about 60% of that in cryostat sections. Immunofluorescent staining after mercury removal can be followed by silver staining for detailed morphologic study of the same 1 μm Paraplast sections. A case of antiglomerular basement membrane glomerulonephritis is illustrated in more detail to show the necessity of alternative methods, including the technique presented, pre-embedding immunofluorescent staining of Epon sections, and electron microscopy, to make a reliable diagnosis of this disease.     

Lipid analyses of human brain rafts

Few studies of lipid rafts have investigated gangliosides in brain tissue. This study focus on analyses of lipids and the major brain gangliosides (GM1, GD1a, GD1b, GT1b) in human cortex (frontal, temporal) and corresponding detergent resistant membranes (DRMs), i.e. rafts. A high proportion of the gangliosides (18–26%) as well as of cholesterol (21%) and sphingomyelin (38%) was found in rafts, while lower yields was observed for ganglioside GM2 (9%), phospholipids (8%) and in particular proteins (2%). Significant alterations in lipid composition was noticed in rafts from Alzheimer brain tissue. These results show that sphingolipids and cholesterol are major constituents of rafts also in the human brain and that the main brain gangliosides are distributed in rafts to a similar degree. Moreover, lipid rafts might be considered in the pathology of Alzheimer's disease.     

Effects of parathyroid hormone on cyclic AMP-formation and cytoplasmic free Ca2+ in the osteosarcoma cell line UMR 106-01

The effects of parathyroid hormone (PTH) on cytoplasmic free CA²⁺ (Ca _i ²⁺ ) and cAMP-formation were investigated in the rat osteosarcoma cell line UMR 106-01.In fura-2 loaded adherent single cells bPTH 1-34 (10 nM–1M) induced a rapid transient increase in Ca _i ²⁺ in 11% of the studied cells. In fura-2 tracings from UMR 106-01 cells in suspension, bPTH 1-34 (0.1 M) induced a transient increase in Ca _i ²⁺ in 20% of the experiments. The transient increase in Ca _i ²⁺ seen in suspensions of cells was not abolished by addition of EGTA (2.5 mM) prior to challenge with PTH, suggesting that the increase in Ca _i ²⁺ was derived from intracellular stores.A marked rapid increase in cAMP-formation was observed in all experiments with cells in suspension, also in the experiments where PTH did not affect Ca _i ²⁺ .These data show that PTH causes a release of Ca²⁺ from intracellular stores in a small percentage of osteosarcoma UMR 106-01 cells, and that PTH is capable of inducing an increase in cAMP-formation without affecting Ca _i ²⁺ in osteoblasts.     

Interferon production by mammalian cells grown in a serum-free medium

Summary Interferon, produced by rabbit heart cells grown in a serum-free medium, failed to protect rabbit heart serum-free cells, but protected rabbit heart serum-containing-medium cells against vaccinia and vesicular stomatitis virus. Interferon produced in serum-free cells had a greater species specificity than that produced in serum-containing media. The difference in activity was shown to be due to lack of adsorption by serum-free-medium cells.