Nuclear envelope proteomics: novel integral membrane proteins of the inner nuclear membrane

The nuclear envelope (NE) is one of the least characterized structures of eukaryotic cells. The study of its functional roles is hampered by the small number of proteins known to be specifically located to it. Here, we present a comprehensive characterization of the NE proteome. We applied different fractionation procedures and isolated protein subsets derived from distinct NE compartments. We identified 148 different proteins by 16-benzyl dimethyl hexadecyl ammonium chloride (16-BAC) gel electrophoresis and matrix-assisted laser desorption ionization (MALDI) mass spectrometry; among them were 19 previously unknown or noncharacterized. The identification of known proteins in particular NE fractions enabled us to assign novel proteins to NE substructures. Thus, our subcellular proteomics approach retains the screening character of classical proteomic studies, but also allows a number of predictions about subcellular localization and interactions of previously noncharacterized proteins. We demonstrate this result by showing that two novel transmembrane proteins, a 100-kDa protein with similarity to Caenorhabditis elegans Unc-84A and an unrelated 45-kDa protein we named LUMA, reside in the inner nuclear membrane and likely interact with the nuclear lamina. The utility of our approach is not restricted to the investigation of the NE. Our approach should be applicable to the analysis of other complex membrane structures of the cell as well.

One-week omeprazole treatment in the diagnosis of gastro-oesophageal reflux disease

BACKGROUND

Symptoms of gastro-oesophageal reflux are common, and currently available methods for diagnosing reflux disease are expensive and uncomfortable for the patient. The diagnostic value of a treatment test with omeprazole is unclear.

METHODS

Patients with dyspepsia including heartburn admitted for upper gastrointestinal endoscopy were studied in a prospective, randomized, double-blind Scandinavian multicentre study. Before entry 188 patients were enrolled, and 160 were randomized to 1-week treatment with 20 mg omeprazole twice daily or placebo. Gastro-oesophageal reflux disease (GERD) was defined as reflux oesophagitis Savary-Miller grades II-III at endoscopy or pH < 4 exceeding 4% of the total time at 24-h oesophageal pH-monitoring and was found in 135 patients. The treatment test was considered positive when the patient's symptoms improved during the treatment week compared with the pretreatment day.

RESULTS

The sensitivity in diagnosing reflux disease was 71-81% with omeprazole as a diagnostic test, compared with 36-47% for placebo during treatment days 3-7. The specificity was similar for the two treatment arms during the first days of the study. During the end of the week a larger proportion of the patients with normal endoscopy and pH test responded to omeprazole treatment, giving omeprazole lower specificity than placebo. The investigators' overall evaluation of whether the patient was a responder to the test had a sensitivity of 75% and a specificity of 55% in the omeprazole-treated patients. The corresponding figures in the placebo group were 17% and 92%, respectively.

CONCLUSION

One week of omeprazole treatment is a simple diagnostic test with a fairly high sensitivity. The specificity is poor owing to the placebo effect and to the lack of a gold standard in diagnosing reflux disease.

A Two-Tiered Approach to Long-Range Climate Forecasting

Long-range global climate forecasts were made by use of a model for predicting a tropical Pacific sea-surface temperature (SST) in tandem with an atmospheric general circulation model. The SST is predicted first at long lead times into the future. These ocean forecasts are then used to force the atmospheric model and so produce climate forecasts at lead times of the SST forecasts. Prediction of seven large climatic events of the 1970s to 1990s by this technique are in good agreement with observations over many regions of the globe.

Interpreting differential temperature trends at the surface and in the lower troposphere

Estimated global-scale temperature trends at Earth's surface (as recorded by thermometers) and in the lower troposphere (as monitored by satellites) diverge by up to 0.14 degrees C per decade over the period 1979 to 1998. Accounting for differences in the spatial coverage of satellite and surface measurements reduces this differential, but still leaves a statistically significant residual of roughly 0.1 degrees C per decade. Natural internal climate variability alone, as simulated in three state-of-the-art coupled atmosphere-ocean models, cannot completely explain this residual trend difference. A model forced by a combination of anthropogenic factors and volcanic aerosols yields surface-troposphere temperature trend differences closest to those observed.

Inotropic effects of calcitonin gene-related peptide, vasoactive intestinal polypeptide and somatostatin on the human right atrium in vitro

Inotropic responses to calcitonin gene-related peptide (alpha-CGRP), substance P, neurokinin A, capsaicin, neuropeptide Y, vasoactive intestinal polypeptide (VIP) and somatostatin (Som, 14 and 28 were analysed using the isolated, electrically driven auricle of the human right atrium. alpha-CGRP and VIP stimulated atrial contractility concentration dependently. alpha-CGRP was about 10-fold more potent than noradrenaline (NA) as an inotropic agent. Phentolamine plus metoprolol decreased the atrial response to NA significantly while the alpha-CGRP effect remained unchanged. Som did not influence the basal contractility of the atria, which, however, was inhibited by acetylcholine (ACh). ACh, Som 14 and Som 28 inhibited the NA-induced stimulation of atrial contractility, whereby Som 28 was more potent than Som 14. The inhibitory effects of ACh were completely blocked by atropine which did not influence the response to Som. Capsaicin, substance P, neurokinin A, neuropeptide Y (NPY) and the NPY fragments 1-19 and 26-36 did not induce any changes in contractility of the electrically driven human atrium. The present results suggest that some of the recently discovered neuropeptides (alpha-CGRP, VIP and Som) could be of importance in the regulation of cardiac contractility in man.

Dopamine infusion in man. Plasma catecholamine levels and pharmacokinetics

Dopamine is widely used in the treatment of hypotensive conditions and/or impending renal failure, but the plasma levels of dopamine and other catecholamines in association with dopamine infusion are not known. Plasma catecholamines and dopamine pharmacokinetics during and after dopamine infusion were therefore studied in man. Two and 5 micrograms x kg-1 x min-1 of dopamine were infused for 30 min in two groups of five patients. Dose-dependent mean steady state levels with fairly large interindividual variations were reached within 5 min. Elimination of dopamine from plasma after termination of infusion had a biphasic course with t 1/2 alpha around 1 min and t 1/2 beta about 9 min in both groups. Noradrenaline plasma levels and blood pressure increased significantly in the 5 micrograms group. It is suggested that the vasoconstriction with deleterious effects on tissue perfusion, seen in conjunction with high-dose dopamine infusion, may be due to increased noradrenaline levels.

Identification of tyrosine-phosphorylated proteins associated with the nuclear envelope

The nuclear envelope separates the nucleoplasm from the rest of the cell. Throughout the cell cycle, its structural integrity is controlled by reversible protein phosphorylation. Whereas its phosphorylation-dependent disassembly during mitosis is well characterized, little is known about phosphorylation events at this structure during interphase. The few characterized examples cover protein phosphorylation at serine and threonine residues, but not tyrosine phosphorylation at the nuclear envelope. Here, we demonstrate that tyrosine phosphorylation and dephosphorylation occur at the nuclear envelope of intact Neuro2a mouse neuroblastoma cells. Tyrosine kinase and phosphatase activities remain associated with purified nuclear envelopes. A similar pattern of tyrosine-phosphorylated nuclear envelope proteins suggests that the same tyrosine kinases act at the nuclear envelope of intact cells and at the purified nuclear envelope. We have also identified eight tyrosine-phosphorylated nuclear envelope proteins by 2D BAC/SDS/PAGE, immunoblotting with phosphotyrosine-specific antibodies, tryptic in-gel digestion, and MS analysis of tryptic peptides. These proteins are the lamina proteins lamin A, lamin B1, and lamin B2, the inner nuclear membrane protein LAP2beta, the heat shock protein hsc70, and the DNA/RNA-binding proteins PSF, hypothetical 16-kDa protein, and NonO, which copurify with the nuclear envelope.

Studies on the biosorption of uranium by Talaromyces emersonii CBS 814.70 biomass

Residual biomass, produced by the thermophilic fungus, Talaromyces emersonii CBS 814.70, following growth on glucose-containing media, was examined for its ability to take up uranium from aqueous solution. It was found that the biomass had a relatively high observed biosorption capacity for the uranium (280 mg/g dry weight biomass). The calculated maximum biosorption capacity obtained by fitting the data to a Langmuir model was calculated to be 323 mg uranium/g dry weight biomass. Pretreatment of the biomass with either dilute HCl or NaOH brought about a significant decrease in biosorptive capacity for uranium. Studies on the effects of variation in temperature on the biosorptive capacity demonstrated no significant change in binding between 20 degrees C and 60 degrees C. However, a significant decrease in biosorptive capacity was observed at 5 degrees C. Binding of uranium to the biomass at all temperatures reached equilibrium within 2 min. While the routine binding assays were performed at pH 5.0, adjustment of the pH to 3.0 gave rise to a significant decrease in biosorption capacity by the biomass. The biosorptive capacity of the biomass for uranium was increased when extraction from solution in sea-water was examined.

Labeling with fluorescent carbocyanine dyes of cultured endothelial and smooth muscle cells by growth in dye-containing medium

We describe a method for labeling cultured endothelial cells (ECs) and smooth muscle cells (SMCs) by letting the cells grow for three days in culture medium containing a low concentration of the fluorescent carbocyanine dyes DiI and DiO. We show that good labeling can be obtained with considerably lower concentrations (2.5 micrograms/ml) than has previously been described. With optimal concentration the labeling is very strong and seems to label all membranous structures in the cells. It was possible to clearly distinguish differentially pre-labeled cells both in coculture and seeded on denaturated vascular grafts. The cells remain fluorescent for more than seven days and may be passaged with retained proliferative capability. We suggest that DiI/DiO-labeling using dye-containing medium may be used for several cell types and is applicable in tissue culture and in the detection of implanted cells in vivo.

Exploring the high-resolution mapping of gender-disaggregated development indicators

Improved understanding of geographical variation and inequity in health status, wealth and access to resources within countries is increasingly being recognized as central to meeting development goals. Development and health indicators assessed at national or subnational scale can often conceal important inequities, with the rural poor often least well represented. The ability to target limited resources is fundamental, especially in an international context where funding for health and development comes under pressure. This has recently prompted the exploration of the potential of spatial interpolation methods based on geolocated clusters from national household survey data for the high-resolution mapping of features such as population age structures, vaccination coverage and access to sanitation. It remains unclear, however, how predictable these different factors are across different settings, variables and between demographic groups. Here we test the accuracy of spatial interpolation methods in producing gender-disaggregated high-resolution maps of the rates of literacy, stunting and the use of modern contraceptive methods from a combination of geolocated demographic and health surveys cluster data and geospatial covariates. Bayesian geostatistical and machine learning modelling methods were tested across four low-income countries and varying gridded environmental and socio-economic covariate datasets to build 1×1 km spatial resolution maps with uncertainty estimates. Results show the potential of the approach in producing high-resolution maps of key gender-disaggregated socio-economic indicators, with explained variance through cross-validation being as high as 74-75% for female literacy in Nigeria and Kenya, and in the 50-70% range for many other variables. However, substantial variations by both country and variable were seen, with many variables showing poor mapping accuracies in the range of 2-30% explained variance using both geostatistical and machine learning approaches. The analyses offer a robust basis for the construction of timely maps with levels of detail that support geographically stratified decision-making and the monitoring of progress towards development goals. However, the great variability in results between countries and variables highlights the challenges in applying these interpolation methods universally across multiple countries, and the importance of validation and quantifying uncertainty if this is undertaken.

Fast track as a routine for open heart surgery

OBJECTIVE

Evaluation of thoracic epidural analgesia (TEA), normothermic cardiopulmonary bypass (CPB) and normothermic blood cardioplegia as a routine procedure for fast track open heart surgery.

METHODS

Consecutive patients (n=250, age 36--81 years, mean 63, M/F, ratio=4) were subjected to the combination of general anaesthesia using ultra-short acting opiates, TEA, normothermic CBP, normothermic whole blood cardioplegia. Operative procedures included coronary artery bypass grafting (CABG), valve replacement, combined CABG and valves, aortic aneurysm and Maze III. LVEF ranged 20--76%. Eighty percent were in Tuman score 0--5 and 20% in score >5.

RESULTS

All patients were extubated within 10 min after skin closure. There was one myocardial infarction. Four percent were shortly treated with cathecholamines. Postoperative atrial fibrillation was noticed in 9.6%. Four transient cerebral ischemic events were encountered. No neurological disturbance related to the use of TEA was seen. Seven patients were reoperated because of bleeding. Blood transfusion was given to 6.4% of the patients. Mortality was 0.8%.

CONCLUSIONS

The combined methods provides a way for routine immediate postoperative extubation, with low morbidity and short hospital stay.

Staphylococcus saprophyticus found to be a common contaminant of food

The mode of transmission of Staphylococcus saprophyticus, a urinary tract pathogen, was investigated in three related studies. The presence of this organism was sought, during a period of 1 year, in 1331 specimens of various foods, in 920 beef and pork carcasses and on 107 cultures which had been inoculated directly from abattoir workers' protective gloves. Staphylococcus saprophyticus was found to contaminate 16.4% of the various food samples with a high prevalence of 34% in raw beef and pork. It was common in both domestic and imported raw meat products. There was no seasonal variation in the presence of S. saprophyticus in the samples obtained from carcasses. The bacterium was found in 69% of all cultures from the workers' protective gloves. We conclude that S. saprophyticus, originating from slaughtered animals, contaminates food and eventually colonizes the human intestinal tract.

An outbreak of Legionnaires' disease in a Swedish hospital

We report a nosocomial outbreak of Legionella pneumophila serogroup (sg) 1 infection at the general hospital, Värnamo, Sweden. From December 1990 to February 1991, 28 patients and 3 staff fell ill with pneumonia and 3 died. L. pneumophila sg 1 together with several other Legionellae were isolated from the hot water supply to 17 of 20 hospital wards, probably being spread by aerosolization via shower nozzles. Raising the hospital's hot water temperature from 45 degrees C to 65 degrees C, together with heat disinfection of the shower equipment, arrested the outbreak within a week. Keeping the hot water temperature > or = 60 degrees C without chlorination eliminated L. pneumophila from > 75% of the wards. During a period of 2 years after the outbreak we have diagnosed only 1 case of nosocomial legionellosis at the hospital despite an active surveillance program.

In vitro endothelialization of commercially available heart valve bioprostheses with cultured adult human cells

The possibility of improving the performance of heart valve bioprostheses by preendothelialization with autologous cells has been suggested. In this study we used cultured adult human vein endothelial cells to endothelialize cusps isolated from commercially available porcine valve bioprostheses. We also describe a method for primary endothelialization of the intact heart valve bioprosthesis. After detoxification of the glutaraldehyde, the cusps or valves were seeded at high density with cultured cells. To obtain an even distribution on the intact valve bioprosthesis, a device was designed which permits application of cells from different directions during rotation. Evaluation was performed by hematoxylin-eosin staining, scanning electron microscopy and immunohistochemistry of the von Willebrand factor and the human basement membrane constituent collagen IV. The endothelial cells were vital-stained during culture by the addition to the culture medium of carbocyanine dye. This made it possible to verify that the endothelium was derived from culture. A confluent lining of cultured endothelial cells in close proximity to a de novo formed basement membrane was observed on the isolated cusps 7 days after seeding. The intact heart valve bioprosthesis showed an even distribution of seeded cells with areas of cells spreading to confluency as evaluated after 24 h. However, 7 days after seeding only unspread and probably dead cells were observed.

Secretion of prostacyclin, tissue plasminogen activator and its inhibitor by cultured adult human endothelial cells grown on different matrices

OBJECTIVES

The aim of this study was to investigate the secretion of prostacyclin (PGI2), tissue plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI- 1) produced by human great saphenous vein endothelial cells (HSVECs) in vitro when seeded to confluency on different matrices.

METHODS

The matrices compared were: uncoated plastic, gelatin, collagen type-I gel, fibronectin, fibrin glue, de-endothelialized porcine aorta and ePTFE vascular grafts pre-coated with collagen type-I or human serum.

RESULTS

There were no significant differences between basal production of PGI2 on the different matrices. The HSVECs responded with a significant increase in PGI2 secretion after stimulation with thrombin on all matrices, including the ePTFE grafts. A statistically significant higher secretion of tPA secretion was found in supernatants from cells cultured on collagen type-I gel. Interestingly, tPA secretion was lower by cells seeded on both collagen type-I and serum precoated ePTFE as compared to collagen type-1 gel. PAI-1 secretion however was significantly higher on collagen type-1 gel, gelatin, fibrin glue and porcine aorta but not on pre-coated ePTFE grafts.

CONCLUSIONS

The findings emphasise the important effect of the matrix on endothelial secretion of PGI2, tPA and PAI-1. Differences in patency after implantation of in vitro endothelialized grafts, may be due to cellular function depending on the types of graft and matrix chosen.

In vitro endothelialization of bioprosthetic heart valves provides a cell monolayer with proliferative capacities and resistance to pulsatile flow

OBJECTIVES

Degeneration of bioprosthetic heart valves has been suggested to be at least partly an immunogenic reaction toward the xenogeneic tissue. An autologous endothelial lining has been proposed to overcome this problem. We examined in vitro endothelialization of such tissue and retention of endothelial cells after exposure to flow resembling the in vivo situation.

METHODS

Cultured human saphenous vein endothelial cells were used to in vitro endothelialize photo-oxidized bioprosthetic heart valves. The endothelialized valves were mounted in a specially designed flow device, creating a pulsatile flow through the valve. Maintenance of a confluent cell layer and deposition of basement membrane markers were determined with immunohistochemical labeling.

RESULTS

Labeling of the main components of the basement membrane, laminin and collagen type IV, was verified within 6 hours after in vitro endothelialization. Under static conditions, 4-mm wide denudations were completely re-endothelialized in 4 days, which was similar to the growth rate on gelatin-coated cell culture plastic, which served as a control material. After exposure of endothelialized valves to pulsatile flows for 24 hours (80 beats/min, 3.4 L/min), there were minimal cell losses from the bioprostheses. The cell layer adapted to the pulsatile flow, as verified by rearrangement of morphology and intracellular stress fibers.

CONCLUSIONS

This study shows the feasibility of in vitro endothelialization of photo-oxidized bioprosthetic heart valves. The cells are able to withstand a pulsatile flow in vitro, to develop basement membrane-like structures, and to re-endothelialize denuded areas. This technology may be used to enhance the performance of bioprosthetic heart valve prostheses.