Nebulin regulates thin filament length, contractility, and Z-disk structure in vivo

The precise assembly of the highly organized filament systems found in muscle is critically important for its function. It has been hypothesized that nebulin, a giant filamentous protein extending along the entire length of the thin filament, provides a blueprint for muscle thin filament assembly. To test this hypothesis, we generated a KO mouse model to investigate nebulin functions in vivo. Nebulin KO mice assemble thin filaments of reduced lengths and approximately 15% of their Z-disks are abnormally wide. Our data demonstrate that nebulin functions in vivo as a molecular ruler by specifying pointed- and barbed-end thin filament capping. Consistent with the shorter thin filament length of nebulin deficient mice, maximal active tension was significantly reduced in KO animals. Phenotypically, the murine model recapitulates human nemaline myopathy (NM), that is, the formation of nemaline rods combined with severe skeletal muscle weakness. The myopathic changes in the nebulin KO model include depressed contractility, loss of myopalladin from the Z-disk, and dysregulation of genes involved in calcium homeostasis and glycogen metabolism; features potentially relevant for understanding human NM.     

A Kdp-like,high-affinity,K+-translocating ATPase is expressed during growth of Rhodobacter sphaeroides in low potassium media

Cells of the purple non-sulphur bacterium Rhodobacter sphaeroides express a high-affinity K⁺ uptake system when grown in media with low K⁺ concentrations. Antibodies againts the catalytic KdpB protein or the whole KdpABC complex of Escherichia coli crossreact with a 70.0 kDa R. sphaeroides protein that was expressed only in cells grown in media with low K⁺ concentrations. In membranes derived from R. sphaeroides cells grown with low K⁺ concentrations (induced cells), a high ATPase activity could be detected when assayed in Tris-HCl pH 8.0 containing 1 mM MgSO₄. This ATPase activity increased upon addition of 1 mM KCl from 166 to 289 mol ATP hydrolysed x min^-1 x g protein^-1 (1.7-fold stimulation). The K⁺-stimulated ATPase activity was inhibited approximately 93% by 0.5 mM vanadate but hardly by N,N-dicyclohexylcarbo-diimide (DCCD). These results indicate that the inducible K⁺-ATPase in R. sphaeroides resembles the Kdp K⁺-translocating ATPase of Escherichia coli. This Kdp-like transport system is also expressed in R. capsulatus and Rhodospirillum rubrum during growth in media with low K⁺ concentrations suggesting a wide distribution of this transport system among phototrophic bacteria.Abbreviations electrical potential difference across the cytoplasmic membrane - pH pH difference across the cytoplasmic membrane - BSA bovine serum albumine - PAGE polyacrylamide gel electrophoresis - HEPES 4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid - PMSF phenyl-methyl-sulfonyl fluoride - DCCD N,N-dicyclohexylcarbodiimide - AIB 2--aminoisobutyric acid - TMG methyl--d-thiogalactopyranoside     

Caffeinated soft drinks reduce bacterial prevalence in voice prosthetic biofilms

Laryngectomized patients use indwelling silicone rubber voice prostheses, placed in a surgically created fistula in between the trachea and the esophagus, for voice and speech rehabilitation. At the esophageal side, these voice prostheses rapidly become colonized by a thick biofilm consisting of a variety of oral and skin bacteria and yeasts, and on average, after 3–4 months a prosthesis has to be replaced. In this study, the influence of caffeinated soft drinks on biofilm formation on silicone rubber voice prostheses has been investigated in a modified Robbins device. Robbins devices were first inoculated with the total cultivable microflora from an explanted voice prosthesis for 3 d, after which the devices were perfused three times daily over a 12 day period with 650 ml of either phosphate buffered saline or carbonated mineral water (controls), caffeinated soft drinks (two types), or a decaffeinated and a sugar‐free version of one of the caffeinated soft drinks. At the end of a day, during the experimental period, the devices were filled with growth medium for 30 min. Both caffeinated soft drinks reduced bacterial prevalence in the biofilms to 1–5% of the control, while yeasts thrived in voice prosthetic biofilms exposed to caffeinated soft drinks. Neither the controls, nor the decaffeinated soft drink, nor the sugar‐free version of this showed these effects on bacterial prevalence.     

Baseline predictors of response and discontinuation of tumor necrosis factor-alpha blocking therapy in ankylosing spondylitis: a prospective longitudinal observational cohort study

Introduction  

Identifying ankylosing spondylitis (AS) patients who are likely to benefit from tumor necrosis factor-alpha (TNF-α) blocking therapy is important, especially in view of the costs and potential side effects of these agents. Recently, the AS Disease Activity Score (ASDAS) has been developed to assess both subjective and objective aspects of AS disease activity. However, data about the predictive value of the ASDAS with respect to clinical response to TNF-α blocking therapy are lacking. The aim of the present study was to identify baseline predictors of response and discontinuation of TNF-α blocking therapy in AS patients in daily clinical practice.     

Correction to: Non-indigenous species along the Israeli Mediterranean coast: tally,policy, outlook

Hydrobiologia - After publication of the above mentioned article, previously undisclosed material was made available resulting in an altered population status for the below mentioned species:     

Physicochemical and structural studies onAcinetobacter calcoaceticus RAG-1 and MR-481—Two standard strains in hydrophobicity tests

Acinetobacter calcoaceticus RAG-1 and MR-481, two standard strains used in microbial adhesion to hydrocarbons (MATH), were characterized by contact angles, pH-dependent zeta potentials, elemental surface composition by X-ray photoelectron spectroscopy (XPS), and molecular composition by infrared spectroscopy (IR). Negatively stained (methylamine tungstate) and ruthenium red-stained cells were studied by transmission electron microscopy to reveal the absence or presence of surface appendages. Despite the fact thatA. calcoaceticus RAG-1 is known to be extremely hydrophobic in MATH, whereas MR-481 is a completely non-hydrophobic mutant, neither XPS nor IR indicated a significant difference in chemical composition of the cell surfaces. Contact angles with polar liquids, water and formamide, were considerably higher on RAG-1 than on MR-481, in accordance with their relative hydrophobicities as measured by MATH. However, no significant differences in contact angles were observed between the two strains with apolar liquids like diiodomethane,-bromonaphthalene, and hexadecane. Fibrous extensions on RAG-1, observed after ruthenium red staining, were absent on the non-hydrophobic mutant MR-481. Tentatively, these extensions could be held responsible for the hydrophobicity ofA. calcoaceticus RAG-1.     

Sex Differences in the Quality of Diabetes Care in the Netherlands (ZODIAC-45)

Objective

Our aim was to investigate whether trends in quality of diabetes care differ between sexes in the Netherlands from 1998 till 2013.

Research Design and Methods

In this prospective observational cohort study quality of care was measured using process and outcome measures in patients with type 2 diabetes in primary care. Trend and absolute differences between sexes were investigated for patients <75 years. Subgroup analyses were performed in patients ≥75 years. 10-year mortality risk was assessed with the Globorisk risk equation in patients without cardiovascular diseases <75 years.

Results

The number of patients increased from 2,644 in 1998 to 62,230 in 2013. In 1998, 51% of the men and 60% of the women <75 years had an HbA1c >53 mmol/mol; this decreased to approximately 29% in both sexes in 2013. Patients having a systolic blood pressure >140 mmHg decreased from 70% to 42%, and from 80% to 40% in men and women <75 years, respectively. In patients ≥75 years it decreased from 72% to 50% in men and 85% to 56% in women. Obesity increased in both sexes, whereas smoking in men and women declined in patients <75 years (men: 34% to 22%; women: 22% to 18%). The number of patients with a mortality risk >20% over 10 years decreased from 15% to 3% in men and from 18% to 3% in women.

Conclusions

Quality of diabetes care has improved considerably in the period 1998–2013 in both sexes. Possibly relevant trend differences between sexes were observed for HbA1c, systolic blood pressure, BMI and smoking. The predicted mortality risk decreased over time in both sexes. Except for BMI in both age groups and systolic blood pressure in patients ≥75 years, no evident poorer risk factor control in women compared to men was found at the end of the study period.     

Relation of growth of Streptococcus lactis and Streptococcus cremoris to amino acid transport.

The maximum specific growth rate of Streptococcus lactis and Streptococcus cremoris on synthetic medium containing glutamate but no glutamine decreases rapidly above pH 7. Growth of these organisms is extended to pH values in excess of 8 in the presence of glutamine. These results can be explained by the kinetic properties of glutamate and glutamine transport (B. Poolman, E. J. Smid, and W. N. Konings, J. Bacteriol. 169:2755-2761, 1987). At alkaline pH the rate of growth in the absence of glutamine is limited by the capacity to accumulate glutamate due to the decreased availability of glutamic acid, the transported species of the glutamate-glutamine transport system. Kinetic analysis of leucine and valine transport shows that the maximal rate of uptake of these amino acids by the branched-chain amino acid transport system is 10 times higher in S. lactis cells grown on synthetic medium containing amino acids than in cells grown in complex broth. For cells grown on synthetic medium, the maximal rate of transport exceeds by about 5 times the requirements at maximum specific growth rates for leucine, isoleucine, and valine (on the basis of the amino acid composition of the cell). The maximal rate of phenylalanine uptake by the aromatic amino acid transport system is in small excess of the requirement for this amino acid at maximum specific growth rates. Analysis of the internal amino acid pools of chemostat-grown cells indicates that passive influx of (some) aromatic amino acids may contribute to the net uptake at high dilution rates.     

Screening of xenobiotics for direct immunotoxicity in an animal study

It has now been recognised that the immune system as a whole can be the target for xenobiotic induced toxicity. The discipline of immuntoxicology encompasses non specific direct immunotoxicity and immunostimulation, and specific responses like hypersensitivity and autoimmunity. Direct immunotoxicity can be determined in tiered studies, TIER 1 being a general toxicity study with emphasis on evaluation of organs belonging to the immune system, TIER 2 investigating the effects of xenobiotics on immune functionality in immunological challenge experiments. In the TIER 1 study, organ weights and histopathological evaluation of immune organs like spleen, thymus, lymph nodes, blood and bone marrow may detect the occurrence of direct immunotoxicity. The follow up studies in the TIER 2 phase can then determine the extent of the immunosuppression and identify which specific parts or cellular components of the immune system are involved. In view of the complexity of the immune system and the multitude of interactions within the immune system in vivo animal experiments are needed to investigate xenobiotics for their potential immunotoxicity. In vitro assays with in vivo exposed cells of the immune system may present additional information on the mechanisms involved in the observed direct immunotoxicity.     

The influence of androgen administration on the structure and function of the brain-pituitary-gonad axis of sexually immature platyfish,Xiphophorus maculatus

Summary This report demonstrates that the administration of testosterone (T) or 11-ketotestosterone (11-KT) to sexually immature (8 wks old) male platyfish (Xiphophorus maculatus) of early-and late-maturing genotypes affects the synthesis and/or release of luteinizing hormone-releasing hormone (LHRH), as assessed by immunocytochemical evaluation, increases the number and activity of pituitary gonadotropes, stimulates the production of sperm and, thus, advances the age of sexual maturation over that dictated by the genome. We also show that 11-KT and T affect different LHRH-containing centers in the brain and have differential effects on rate and degree of sexual maturation, regardless of whether the hormones are administered to early or late-maturing genotypes.