A fast sol–gel synthesis leading to highly crystalline birnessites under non-hydrothermal conditions

Manganese oxides from the compound family of layered birnessites have attracted interest for their use as cathode materials in Li-ion batteries, as supercapacitors, and as water oxidation catalysts.

Inhibitor-assisted synthesis of silica-core microbeads with pepsin-imprinted nanoshells

An innovative approach for imprinting proteins based on inhibitor-assisted templating of core–nanoshell microbeads is developed to address the challenges in protein purification.

Cellular recognition and macropinocytosis-like internalization of nanoparticles targeted to integrin α2β1

Targeting nanoparticles to desired intracellular compartments is a major challenge. Integrin-type adhesion receptors are connected to different endocytosis routes in a receptor-specific manner. According to our previous observations, the internalization of an α2β1-integrin-echovirus-1 complex takes place via a macropinocytosis-like mechanism, suggesting that the receptor could be used to target nanoparticles to this specific entry route. Here, silica-based nanoparticles, carrying monoclonal antibodies against the α2β1 integrin as address labels, were synthesized. Studies with flow cytometry, atomic force microscopy and confocal microscopy showed the particles to attach to the cell surface via the α2β1 integrin. Furthermore, quantitative analysis of nanoparticle trafficking inside the cell performed with the BioImageXD software indicated that the particles enter cells via a macropinocytosis-like process and end up in caveolin-1 positive structures. Thus, we suggest that different integrins can guide particles to distinct endocytosis routes and, subsequently, also to specific intracellular compartments. In addition, we show that with the BioImageXD software it is possible to conduct sensitive and complex analyses of the behavior of small fluorescent particles inside cells, using basic confocal microscopy images.

Multiple sclerosis risk genotypes correlate with an elevated cerebrospinal fluid level of the suggested prognostic marker CXCL13

Background:

The mechanisms of multiple sclerosis (MS) pathogenesis are still largely unknown. The heterogeneity of disease manifestations make the prediction of prognosis and choice of appropriate treatment protocols challenging. Recently, increased cerebrospinal fluid (CSF) levels of the B-cell chemokine CXCL13 was proposed as a possible marker for a more severe disease course and conversion from clinically isolated syndrome (CIS) to relapsing–remitting MS (RRMS).

Objective:

To investigate whether there are genetic susceptibility variants in MS that correlate with the levels of CXCL13 present in the CSF of MS patients.

Methods:

We genotyped the human leukocyte antigens HLA-DRB1 and HLA-A, plus a panel of single nucleotide polymorphisms (SNPs) that have been associated with susceptibility to MS and then correlated the genotypes with the levels of CXCL13, as measured with ELISA in the CSF of a total of 663 patients with MS, CIS, other neurological diseases (OND) or OND with an inflammatory component (iOND).

Results:

Presence of the HLA-DRB1*15 and the MS risk genotypes for SNPs in the RGS1, IRF5 and OLIG3/TNFAIP3 gene regions correlated significantly with increased levels of CXCL13.

Conclusion:

Our results pointed towards a genetic predisposition for increased CXCL13 levels, which in MS patients correlates with the severity of the disease course. These findings encourage further investigation and replication, in an independent patient cohort.

Epstein-Barr virus and multiple sclerosis: interaction with HLA

Epstein-Barr virus (EBV) infection, history of infectious mononucleosis (IM) and HLA-A and DRB1 have all been proposed as risk factors for multiple sclerosis (MS). Our aim was to analyse possible interactions between antibodies against Epstein-Barr virus nuclear antigen 1 (EBNA1) or EBNA1 fragments, presence of DRB1*15 and absence of A*02. The study population includes newly diagnosed cases and matched controls. Interaction on the additive scale was calculated using attributable proportion due to interaction (AP), which is the proportion of the incidence among individuals exposed to two interacting factors that is attributable to the interaction per se. IM showed association with MS, odds ratio (OR)=1.89 (1.45-2.48% confidence interval (CI)), as did raised EBNA1 IgG OR=1.74 (1.38-2.18 95%CI). All EBNA1 fragment IgGs were associated with MS risk. However, EBNA1 fragment 385-420 IgG levels were more strongly associated to MS than total EBNA1 IgG, OR=3.60 (2.75-4.72 95%CI), and also interacted with both DRB1*15 and absence of A*02, AP 0.60 (0.45-0.76 95%CI) and AP 0.39 (0.18-0.61 95%CI), respectively. The observed interaction between HLA class I and II genotype and reactivity to EBV-related epitopes suggest that the mechanism through which HLA genes influence the risk of MS may, at least in part, involve the immune control of EBV infection.

The role played by salts in the formation of SBA-15, an in situ small-angle X-ray scattering/diffraction study

The influence of salts (NaCl, NaBr, and NaI) on the formation of mesoporous silica SBA-15 was studied in situ by small-angle X-ray scattering and diffraction. Pluronic P104 was used as structure director. The micellar properties and the dynamics of formation were clearly dependent on the presence of salt. It was also shown that the kinetics of mesophase formation, the initial value of the cell parameters, and the extent of long-range order were all influenced by salt additions. The observations are explained to primarily originate from the influence of the anions on the ethylene oxide part of the polymer, i.e., the corona region of the Pluronic micelles. Two effects are identified: a general ion effect causing dehydration of the ethylene oxide part and consequently inducing micellar growth, and a specific ion effect that counterbalances this. The study provides the basis for understanding the means by which addition of simple Na-salts influence the formation of mesoscopically ordered silicas synthesized using nonionic surfactants as structure directors, hence advancing the knowledge base toward a more rational design of mesoporous materials.

Rapid subcutaneous immunoglobulin administration every second week results in high and stable serum immunoglobulin G levels in patients with primary antibody deficiencies

Subcutaneous immunoglobulin G (SCIG) infusions as life-long replacement therapy in patients with primary antibody deficiences (PAD) is being applied increasingly. However, only a few published pharmacokinetic studies are available for this route of administration. Therefore, the pharmacokinetics of a 16% immunoglobulin G (IgG) preparation intended for subcutaneous use were investigated in patients with common variable immunodeficiency and X-linked agammaglobulinaemia. SCIG infusions (200 mg/kg body weight) were administered to 12 adult patients every 14 days for 24 weeks (total of 144 infusions). Pharmacokinetic parameters were determined based on serum IgG trough levels and antibody levels against tetanus. The median half-life of the total serum IgG and for the tetanus antibodies was 40.6 and 23.3 days respectively. Median in vivo recovery of serum IgG and tetanus immunoglobulins were 36% and 46% respectively. Median, preinfusion serum IgG trough levels per patient were high without major variations between infusions and ranged from 7.24 to 7.86 g/l. Safety, in terms of adverse events including systemic adverse reactions and local tissue reactions at infusions sites, was monitored throughout the study. Six mild, local tissue reactions were observed during the study in one patient. No systemic adverse reactions related to the study drug were observed and no serious other adverse event occurred during the study. It is concluded that the bi-weekly SCIG therapy was well tolerated in the study and that it results in high and stable serum IgG levels, offering an alternative therapy regimen to patients suffering from PAD.

Detection of human coronavirus NL63, human metapneumovirus and respiratory syncytial virus in children with respiratory tract infections in south-west Sweden

Two recently detected viruses, human metapneumovirus (hMPV) and coronavirus NL63 (HCoV‐NL63), have been associated with acute respiratory tract infections, particularly in young children. This study investigated the frequency of hMPV and HCoV‐NL63 infections in Swedish children by screening 221 nasopharyngeal aspirates, collected between November 2003 and May 2005, from 212 children attending the paediatric department of a county hospital in Sweden or submitted from local general practitioners. The samples were originally submitted to be tested for respiratory syncytial virus (RSV), and were examined retrospectively for hMPV and HCoV‐NL63 by RT‐PCR. Of the 212 patients, 101 were positive for RSV (48%), 22 (10%) were positive for hMPV, and 12 (6%) were positive for HCoV‐NL63. The frequency of HCoV‐NL63 infection increased from 1% in 2003–2004 to 10% in 2004–2005. Sequence analysis of parts of the coronavirus genomes showed considerable similarity to the HCoV‐NL63 prototype sequence. The study demonstrated that HCoV‐NL63 and hMPV occur in south‐west Sweden with essentially the same frequency, seasonal distribution and clinical characteristics as have been reported in other countries.

Evaluation of antidecubitus mattresses

Pressure sores are a current problem in hospitals and care of the elderly, leading to protracted hospital stays and a high care burden. The trauma for the patients is severe, and the cost of pressure sore prevention and treatment, is considerable. Antidecubitus mattresses are used for prevention and in treatment, but they also contribute to the cost of treating pressure sores. The problem highlighted in the review is that the mattresses' effectiveness in preventing and treating pressure sores has not been sufficiently evaluated. When antidecubitus mattresses are evaluated, it is often only with regard to aspects of the interface pressure and the mattresses' ability to redistribute the pressure. The review points out the important observation that, to be able to evaluate the efficacy of the antidecubitus mattress, the mattress's effect on tissue viability needs to be studied. The parameters that ought to be considered when evaluating a support surface are: interface pressure, pressure and blood flow distribution, temperature and humidity in the skin-support surface interface. The authors propose that the effect on tissue viability of external loading can be assessed by simultaneous measurement of the interface pressure and tissue perfusion.

One-pot aerosol synthesis of ordered hierarchical mesoporous core–shell silica nanoparticles

A mixed surfactant approach has been successfully employed in an aerosol-based synthesis of spherical silica particles exhibiting a new core-shell structure where the shell and the core exhibit different ordered mesoporosity and pore sizes.

Effects of desmin gene knockout on mice heart mitochondria

In heart tissue from mice lacking the intermediate filament (IF) desmin, mitochondria show an abnormal shape and distribution (Thornell et al., 1997). In the present study we have isolated heart mitochondria from desmin null (D-/-) and control (D+/+) mice, and analyzed their composition by SDS-PAGE, immunoblotting, and enzyme measurements. We found both in vitro and in situ that the conventional kinesin, the microtubule-associated plus-end directed motor, was frequently associated with D+/+ heart mitochondria, but not with D-/- heart mitochondria, suggesting that the positioning of mitochondria in heart is a dynamic event involving the IF desmin, the molecular motor kinesin, and, most likely, the microtubules (MT) network. Furthermore, an increased capacity in energy production was found, as indicated by a threefold higher creatine kinase activity in heart mitochondria from D-/- compared to D+/+ mice. We also observed a significantly lower amount of cytochrome c in heart mitochondria from D-/- mice, and a relocalization of Bcl-2, which may indicate an apoptotic condition in the cell leading to the earlier reported pathological events, such as cardiomyocytes degeneration and calcinosis of the heart (Thornell et al., 1997).

Genetic variation and population structure in Scandinavian wolverine (Gulo gulo) populations

Wolverine (Gulo gulo) numbers in Scandinavia were significantly reduced during the early part of the century as a result of predator removal programmes and hunting. Protective legislation in both Sweden and Norway in the 1960s and 1970s has now resulted in increased wolverine densities in Scandinavia. We report here the development of 15 polymorphic microsatellite markers in wolverine and their use to examine the population sub-structure and genetic variability in free-ranging Scandinavian wolverine populations as well as in a sample of individuals collected before 1970. Significant subdivision between extant populations was discovered, in particular for the small and isolated population of southern Norway, which represents a recent recolonization. Overall genetic variability was found to be lower than previously reported for other mustelids, with only two to five alleles per locus and observed heterozygosities (H(O)) ranging from 0.269 to 0.376 across the examined populations, being lowest in southern Norway. Analysis of the mitochondrial DNA control region revealed no variation throughout the surveyed populations. As the historical sample did not show higher levels of genetic variability, our results are consistent with a reduction in the genetic variation in Scandinavian wolverines that pre-dates the demographic bottleneck observed during the last century. The observed subdivision between populations calls for management caution when issuing harvest quotas, especially for the geographically isolated south Norwegian population.

A 252Cf-based instrument for in vivo body protein monitoring in cancer patients

A hospital-based facility for in vivo prompt gamma neutron activation analysis of nitrogen for body protein determination is described. The patient is laid on a movable couch and is scanned with a vertically collimated neutron beam from a 252Cf neutron source (the amount of Cf varying from 120 to 40 microg due to the physical decay) positioned below the patient. Four large NaI(Tl) detectors are used to measure the 10.8 MeV gamma-rays from nitrogen. To check the long-term stability of the system, a solid phantom simulating the geometry of the adult human trunk, having similar elemental composition as tissue, was constructed. Repeated phantom measurements over 6 months gave a reproducibility in nitrogen determination of 2.9% (1 SD). Duplicate patient measurements carried out within a week showed a reproducibility of 5% (1 SD). A calibration method for absolute protein measurements in patients is presented. Patients are normally measured for 40 min; giving a mean whole-body equivalent dose of 0.25 mSv. Results from measurements on 13 cancer patients are presented.

Red blood cell velocity and volumetric flow assessment by enhanced high-resolution laser Doppler imaging in separate vessels of the hamster cheek pouch microcirculation

An enhanced high-resolution laser Doppler imager (EHR-LDI), configured to fit the demands of a measurement area containing separate microvessels, was evaluated for perfusion measurements in hamster cheek pouch preparations during ischemia, reperfusion, and pharmacologically induced vasodilation and vasoconstriction. Measurements in separate microvessels where the laser beam was smaller than the vessel diameter were referred to as red blood cell (RBC) velocity estimates, as previously validated in vitro, whereas a relative flow index, RFI (mean RBC velocity/tissue area), was introduced as a volumetric flow measure. Microvessel diameter and RBC velocity changes during ischemia, reperfusion, as well as during vasoconstriction and vasodilation correlated to the data obtained from the microscope. Correspondingly, during the described provocations anticipated volumetric flow changes were registered as changes in the RFI. When data on intravessel RBC velocity profiles are presented they reflect a parabolic flow profile usually seen in this size microvessel. The EHR-LDI appears a promising tool for investigation of the microvasculature, as it almost simultaneously provides information on relative changes of both in vivo RBC velocity and volumetric flow (RFI), although the latter estimate needs to be further refined.

Evaluation of enhanced high-resolution laser Doppler imaging in an in vitro tube model with the aim of assessing blood flow in separate microvessels

An enhanced high-resolution laser Doppler imaging (EHR-LDI) technique intended for visualization of separate microvessels was evaluated by use of in vitro flow models. In EHR-LDI, a laser beam focused to a half-power diameter less than 40 microm successively scans the tissue under study in steps of 25 microm. Spatial blood flow variations within microvascular structures of 1.5 x 1.5 mm are rendered by 64 x 64 measurement sites. Individual microvessel diameters could be estimated and an average difference of 11 microm compared to microscopic measurements was obtained. For the flow algorithm used, the LDI output signal was found to scale linearly with average velocity (0-3.5 mm/s) when a plastic tube of inner diameter 175 microm was perfused with human blood (correlation coefficient 0.99). The LDI output signal was further found insensitive to hematocrit variations in the range 16-44%. Due to the limited laser light penetration in blood, a reduction in the LDI output signal was observed as the inner tube diameters were successively changed from 280 to 1400 microm.

Can blood flow in separate small tubes be quantitatively assessed by high-resolution laser Doppler imaging?

A method is suggested for quantitative flow assessment of whole-blood perfusing tubes with diameters in the range from 500 microns to 1.5 mm, for velocities below 9 mm s-1. The algorithm is based both on the Doppler broadening of backscattered laser light and the magnitude of the diameter of the perfused tube. A bandwidth-modified high-resolution laser Doppler perfusion imaging system is used to record the Doppler broadening. A flow model, consisting of a linearly narrowing tube (inner diameter 620-1330 microns), is connected to a precision infusion pump and perfused by human whole blood of volume flows ranging from 0 to 6.6 mm3 s-1. Empirical data are fitted into a regression model, and the parameters of the algorithm can be determined, resulting in a correlation coefficient of 0.975 between the predicted and true volume flows. Using this algorithm, volume flows in tubes of inner diameters of 500 microns, 750 microns and 1.4 mm are predicted, with accuracies corresponding to correlation coefficients of 0.994, 0.993 and 0.996.

Identification of porin as a binding site for MAP2

Porin or VDAC, the pore forming protein in the outer mitochondrial membrane, was identified as a binding site for microtubule-associated protein 2 (MAP2). By affinity chromatography using covalently bound MAP2, two proteins were selectively purified with molecular weights 63 and 70 KD. The 63 KD protein was identified to be the dimer of porin using affinity purified porin antibodies.

Laser-Doppler perfusion imaging of microvascular blood flow in rabbit tenuissimus muscle

To evaluate a newly developed high-resolution laser-Doppler perfusion imager (HR-LDPI) for analysis of local tissue perfusion, blood flow measurements in the rabbit tenuissimus muscle were carried out in combination with intravital microscopic observation. The principle of the LDPI method is based on a low-power laser beam scan of the exposed tissue from which a two-dimensional color-coded perfusion map is created through computerized signal analysis. The perfusion of the tenuissimus muscle prepared for microscopic observation was analyzed in a 5 mm x 8 mm area as the muscle was exposed to atmospheric oxygen tension (Po2; 20 kPa), a low Po2 (approximately 3 kPa), and after vasodilatation induced by topical application of prostaglandin E2 (PGE2). In selected areas free from larger vessels, a significantly lower perfusion average reading was demonstrated under high Po2 conditions compared with low Po2 conditions (P < 0.05, n = 5 animals), and application of PGE2 gave rise to an average reading significantly higher than that at low Po2 (P < 0.01, n = 6 animals). The results were in good agreement with the flow changes observed microscopically, and the architecture of the microvascular network, as depicted by in vivo micrographs, was clearly recognizable in the perfusion images. In conclusion, blood flow changes in the rabbit tenuissimus muscle induced by various stimuli were quantitated with the HR-LDPI method and could be spatially resolved in great detail, illustrating the potential of using HR-LDPI for analysis of local blood flow and to reveal spatial perfusion heterogeneity in tissues.

Statistical analysis of the surface distribution of microtubule-associated proteins (MAPs) bound in vitro to rat brain mitochondria and labelled by 10 nm gold-coupled antibodies

Purified mitochondria from rat brain were incubated in vitro which microtubule-associated proteins (MAPs) that are known to bind specifically on sites present on the outer membrane. The bound molecules were detected by immunoelectron microscopy and the linear distribution of the label along mitochondrial profiles was analyzed by statistical methods. The results demonstrate that gold-conjugated antibodies are distributed in a non-random fashion on the surface of mitochondria, suggesting regional concentrations of MAPs-binding sites. This finding argue for the existence of specialized domains on mitochondria that are involved in the association of the organelles to microtubules in situ.

The effect of dopamine on adenylate cyclase and Na+,K(+)-ATPase activity in the developing rat renal cortical and medullary tubule cells

Dopamine has an age-dependent natriuretic and diuretic effect. We have investigated the ontogeny of the dopamine response on adenylate cyclase activity and Na+,K(+)-ATPase activity in two different cell populations in the infant (10-d-old) and the adult (40-d-old) rat kidney. Basal- and forskolin-stimulated adenylate cyclase activity in tubular suspensions of renal cortex was 5.4-fold (p < 0.05) higher in the 10-d-old rats than in the 40-d-old rats but unchanged between the ages in a suspension of medullary tubules. The dopamine-1-specific agonist fenoldopam did not stimulate adenylate cyclase activity in the cortical cells from 10-d-old rats but did stimulate activity 51 +/- 16% (p < 0.05) in the 40-d-old rats. In the medullary suspension, fenoldopam stimulated adenylate cyclase activity by 43.5 +/- 5% (p < 0.001) in the 10-d-old rats and by 32.0 +/- 7% (p < 0.01) in the 40-d-old rats. In the isolated proximal convoluted tubule, dopamine inhibited Na+,K(+)-ATPase activity in both the 10-d-old (34 +/- 3%, p < 0.001) and 40-d-old rats (44 +/- 7%, p < 0.001). In contrast, in the medullary thick ascending limb of Henle, inhibition of Na+,K(+)-ATPase activity by fenoldopam was more pronounced in the 10-d-old (56 +/- 6%, p < 0.001) than in the 40-d-old rat (33 +/- 6%, p < 0.001). In summary, the renal tubular effects of dopamine on adenylate cyclase and Na+,K(+)-ATPase activity change during postnatal development in a cell-specific manner.

Work organisation, work environment and the use of medical equipment: a survey study of the impact on quality and safety

In a study of hospital staff's perceived quality of care and worry, related to the use of medical equipment, a systems approach was used. This included training and user aspects on the equipment, environmental ergonomics, work organisation and psychosocial work conditions. In a survey study, 543 hospital staff members from seven departments with various degrees of equipment utilisation participated. By means of factor analysis, factors which were important to perceived quality of care and worry were determined. Adaptation of equipment and environment and training on the use of equipment were shown to be important. However, several organisational and psychosocial factors turned out to have a still greater impact. In the assessment of healthcare technologies which include medical equipment a holistic systems approach is therefore advocated.

Neutrophil killing of two type 1 fimbria-bearing Escherichia coli strains: dependence on respiratory burst activation

The production of reactive oxygen metabolites by neutrophils is thought to play a key role in host defense against invading microorganisms. In this study, the generation of oxygen metabolites induced by two uropathogenic Escherichia coli strains, ABU2 and PN7, and their subsequent killing in neutrophils were investigated. Both strains were grown to promote type 1 (mannose-sensitive) fimbria formation, but they differ with respect to other surface structures. When interacting with human neutrophils, the ABU2 bacteria adhered to and were phagocytized by the neutrophils, whereas PN7 bacteria adhered to the neutrophils but resisted phagocytosis. Both strains induced a pronounced neutrophil chemiluminescence response. However, when the intracellular and extracellular parts of the oxidative response were separated, we found that the predominant part of the response was of intracellular origin with the ABU2 bacteria as prey, whereas a large fraction of the response induced by the PN7 bacteria was extracellular. The general opinion is that production of reactive oxygen metabolites should be intraphagosomal to minimize the tissue-damaging effects of the metabolites and to optimize their bactericidal effects. However, since the surface-adherent bacteria (the PN7 cells) are killed in an aerobic but not an anaerobic milieu, whereas the ingested bacteria (the ABU2 cells) are killed in both aerobic and anaerobic milieu, we propose that extracellularly generated oxygen metabolites are of importance in killing E. coli strains that can resist neutrophil engulfment.

Studies on the interaction between mitochondria and the cytoskeleton

Mitochondrial movements and morphology are regulated through interactions with the cytoskeletal system, in particular the microtubules. An interaction between the microtubule-associated proteins (MAPs) and the outer surface of rat brain mitochondria has been demonstrated in vitro and in situ. One of the MAPs, MAP2, binds to specific high-affinity sites on the outer membrane. Upon binding, MAP2 is released from microtubules, and it induces a physical alteration in the outer membrane which is characterized by a tighter association of porin with the membrane. It is concluded that MAP2 either binds to porin or to a domain of the outer membrane which alters the membrane environment of porin. The possibility is raised that this domain participates in mitochondrial mobility in situ.

The specific binding of the microtubule-associated protein 2 (MAP2) to the outer membrane of rat brain mitochondria

Purified mitochondria from rat brain contain microtubule-associated proteins (MAPs) bound to the outer membrane. Studies of binding in vitro performed with microtubules and with purified microtubule proteins showed that mitochondria preferentially interact with the high-molecular-mass MAPs (and not with Tau protein). Incubation of intact mitochondria with Taxol-stabilized microtubules resulted in the selective trapping of both MAPs 1 and 2 on mitochondria, indicating that an interaction between the two organelles occurred through a site on the arm-like projection of MAPs. Two MAP-binding sites were located on intact mitochondria. The lower-affinity MAP2-binding site (Kd = 2 x 10(-7) M) was preserved and enriched in the outer-membrane fraction, whereas the higher-affinity site (Kd = 1 x 10(-9) M) was destroyed after removing the outer membrane with digitonin. Detergent fractionation of mitochondrial outer membranes saturated with MAP2 bound in vitro showed that MAPs are associated with membrane fragments which contain the pore-forming protein (porin). MAP2 also partially prevents the solubilization of porin from outer membrane, indicating a MAP-induced change in the membrane environment of porin. These observations demonstrate the presence of specific MAP-binding sites on the outer membrane, suggesting an association between porin and the membrane domain involved in the cross-linkage between microtubules and mitochondria.

Studies on the relationship between the inner and outer membranes of rat liver mitochondria as determined by subfractionation with digitonin

The present investigation has attempted to define in rat liver mitochondria the distribution of outer membrane proteins in relation to the inner membrane by fractionation with digitonin and phospholipase A2. Porin, the channel-forming protein in the outer membrane, was measured quantitatively by immunological methods. Neither monoamine oxidase nor porin could be released by phospholipase A2 treatment, but both were released by digitonin, at the same detergent concentration. Thus, the release of monoamine oxidase and porin requires the disruption of the cholesterol but not the phospholipid domains of the membrane and the two polypeptides exist in the same, or similar, membrane environment with regard to cholesterol. Changes in the energy state, or binding of brain hexokinase to rat liver mitochondria prior to fractionation with digitonin, did not alter the release patterns of porin and monoamine oxidase. The uptake of Ca2+, however, resulted in the concomitant release of the outer membrane markers together with the matrix marker, malate dehydrogenase. The present findings with liver differ from those obtained recently with brain mitochondria (L. Dorbani et al. (1987) Arch. Biochem. Biophys. 252, 188-196) in which two populations of porin were located in two different cholesterol domains. The significance of these differences in the location of porin in liver and brain mitochondria is discussed.

Budesonide nasal spray as prophylactic treatment after polypectomy (a double blind clinical trial)

This double-blind parallel-group study compared the effect of budesonide with placebo, in the prophylaxis of nasal polyp recurrence after evulsion. Seventy-three patients with first time or recurrent polypectomy were enrolled. At revisits 3 and 6 months after evulsion, the budesonide-treated patients had significantly lower polyp scores than the placebo-treated patients. Only patients with recurrent nasal polyposis benefited from the budesonide treatment, whereas no effect was evident in patients with first time evulsion.

Immunochemical analysis of the membrane proteins of rat liver and Zajdela hepatoma mitochondria

The contents of mitochondrial inner membrane protein complexes were compared in normal liver and in Zajdela hepatoma mitochondria by the immunotransfer technique. Antibodies against core proteins 1 and 2, cytochrome c1, the iron-sulfur protein of Complex III, subunits I and II of cytochrome oxidase, and the alpha and beta subunits of the F1-ATPase were used. In addition, antibodies against a primary dehydrogenase, beta-hydroxybutyrate dehydrogenase, as well as the outer membrane pore protein were used. The results indicate that the components of the cytochrome chain and porin are greatly enriched in hepatoma mitochondria compared to normal rat liver mitochondria. This enrichment was also reflected in the rates of respiration in tumor mitochondria using a variety of substrates. Enrichment of porin may partially account for increased hexokinase binding to tumor mitochondria. In contrast to the respiratory chain components, the F1-ATPase and F0 (measured by DCCD binding) were not increased in tumor mitochondria. Thus, Zajdela hepatoma mitochondria components are nonstoichiometric, being enriched in oxidative capacity but relatively deficient in ATP synthesizing capacity. Finally, beta-hydroxybutyrate dehydrogenase, which is often decreased in hepatoma mitochondria, was shown here by immunological methods to be decreased by only 40%, whereas enzyme activity was less than 5% of that in normal rat liver.

Subcellular distribution of rat liver porin

The subcellular distribution of rat liver porin was investigated using the immunoblotting technique and monospecific antisera against the protein isolated from the outer membrane of rat liver mitochondria. Subfractionation of mitochondria into inner membranes, outer membranes and matrix fractions revealed the presence of porin only in the outer membranes. Porin was also not detected in highly purified subcellular fractions, including plasma membranes, nuclear membranes, Golgi I and Golgi II, microsomes and lysosomes. Thus, liver porin is located exclusively in the outer mitochondrial membrane.

Hydrodynamic properties of porin isolated from outer membranes of rat liver mitochondria

The hydrodynamic properties of purified porin (Mr = 30 000), isolated from outer membranes of rat liver mitochondria has been studied. After gel filtration, active porin was eluted in a symmetrical peak with an estimated Stokes radius of 5.4 nm. The sedimentation coefficient (s) and partial specific volume (v) were found to be 2.6 S and 0.908 cm3/g, respectively, for the purified porin-Triton X-100 complex. Based on these determinations, a molecular weight of 170 000 for the porin-Triton X-100 complex was calculated. Correcting for bound Triton X-100, 1.8 g/g of protein, a molecular weight of 60 000 was estimated for the protein portion of the complex. Thus, isolated active porin appears to exist as a dimer.

Purification of a protein having pore forming activity from the rat liver mitochondrial outer membrane

A protein with pore-forming activity has been isolated from the outer membrane of rat liver mitochondria. The purification involves sucrose gradient centrifugation, differential centrifugation in the presence of Triton X-100, and DEAE-Sepharose and CM-Sepharose chromatography. The yield of the purified protein was approx. 2% of the total outer membrane proteins. The protein, when inserted into soya bean phospholipid vesicles, increases the [3H]sucrose permeability of the vesicles but had no effect on the permeability of high-molecular-weight [14C]dextran (Mr 70 000). The protein is very active, since as little as 3-4 micrograms of protein per mg of phospholipid is required for the complete release of [3H]sucrose from the vesicles. Sucrose diffusion channels could not be reconstituted with other membrane proteins such as rat liver cytochrome oxidase or cytochrome b5. Purified pore protein revealed a single band of apparent Mr 30000 when resolved by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. This polypeptide could be further resolved by isoelectric focusing into a major (pI7.9) and two relatively minor (pI7.6 and 7.2) components. Proteolytic mapping with V8 proteinase from Staphylococcus aureus suggests that these probably represent a single component showing charge heterogeneity. The reason for the charge heterogeneity is not known. The amino acid composition of the protein revealed 47.8% polar amino acids with a relatively high lysine content.