Intraoral lubrication of PRP-1, statherin and mucin as studied by AFM

The aim of this paper was to elucidate the mechanisms behind salivary lubrication with special emphasis on the lubricity of three key components of the pellicle, viz human acidic proline-rich protein 1 (PRP-1), human statherin and bovine submaxillary mucin (BSM). The lubricating properties of the proteins have been assessed by means of colloidal probe atomic force microscopy, and are discussed in relation to their adsorption behaviour. To various extents, the proteins investigated all showed a lubricating effect when adsorbed to silica surfaces. For comparable concentrations, PRP-1 was found to have a more pronounced lubricating effect than BSM, which in turn showed a higher lubricity than statherin. The relative lubricity is in accordance with previously reported relative adsorbed amounts of the three proteins, within the investigated concentration interval. It is concluded that PRP-1 has the highest lubricating capacity as a pure fraction among the preparations investigated, and that the lubricating effect of PRP-1 as a pure fraction is notably large as compared to the lubricity of human whole saliva.     

Membrane topology and sequence requirements for oil body targeting of oleosin

Oleosin protein is targeted to oil bodies via the endoplasmic reticulum (ER) and consists of a lipid-submerged hydrophobic (H) domain that is flanked by cytosolic hydrophilic domains. We investigated the relationship between oleosin ER topology and its subsequent ability to target to oil bodies. Oleosin variants were created to yield differing ER membrane topologies and tagged with a reporter enzyme. Localisation was assessed by fractionation after transient expression in embryonic cells. Membrane-straddled topologies with N-terminal sequence in the ER lumen and C-terminal sequence in the cytosol were unable to target to oil bodies efficiently. Similarly, a translocated topology with only ER membrane and lumenal sequence was unable to target to oil bodies efficiently. Both topology variants accumulated proportionately higher in ER microsomal fractions, demonstrating a block in transferring from ER to oil bodies. The residual oil body accumulation for the inverted topology was shown to be because of partial adoption of native ER membrane topology, using a reporter variant, which becomes inactivated by ER-mediated glycosylation. In addition, the importance of H domain sequence for oil body targeting was assessed using variants that maintain native ER topology. The central proline knot motif (PKM) has previously been shown to be critical for oil body targeting, but here the arms of the H domain flanking this motif were shown to be interchangeable with only a moderate reduction in oil body targeting. We conclude that oil body targeting of oleosin depends on a specific ER membrane topology but does not require a specific sequence in the H domain flanking arms.     

Successful predation of filamentous bacteria by a nanoflagellate challenges current models of flagellate bacterivory

Current models suggest that (i) filamentous bacteria are protected against predation by nanoflagellates, (ii) prey size is positively correlated with prey-predator contact probability, and (iii) contact probability is mainly responsible for size-selective predation by interception-feeding flagellates. We used five strains of filamentous bacteria and one bacterivorous nanoflagellate, Ochromonas sp. strain DS, to test these assumptions. The five strains, including one spirochete and four Betaproteobacteria strains, were isolated by the filtration-acclimatization method. All five strains possess flexible cells, but they differ in average cell length, which ranged from 4.5 to 13.7 micro m. High-resolution video microscopy was used to measure contact, capture, and ingestion rates, as well as selectivity of the flagellate feeding. Growth and feeding experiments with satiating and nonsatiating food conditions, as well as experiments including alternative well-edible prey, were performed. In contrast to predictions by current models, the flagellate successfully consumed all the tested filamentous strains. The ingestion rate was negatively correlated with bacterial length. On the other hand, the lengths of the filamentous bacteria were not positively correlated to the contact rate and capture rate but were negatively correlated to ingestion efficiency. In experiments including alternative nonfilamentous prey, the flagellates showed negative selection for filamentous bacteria, which was independent of food concentration and is interpreted as a passive selection. Our observations indicate that (i) size alone is not sufficient to define a refuge for filamentous bacteria from nanoflagellate predation and (ii) for the investigated filamentous bacteria, prey-predator contact probability could be more influenced by factors other than the prey size.     

Electrotransfer of human IL-1Ra into skeletal muscles reduces the incidence of murine collagen-induced arthritis

BACKGROUND: It has previously been demonstrated that high levels of gene expression in skeletal muscles can be achieved after direct in vivo electrotransfer of naked plasmid DNA. The purpose of this study is to examine the potential of in vivo electroporation of plasmid DNA encoding human IL-1Ra for the prevention of murine collagen-induced arthritis (CIA). METHODS: DBA/1 mice were injected in gastrocnemius muscles with plasmid DNA followed by in vivo electroporation. To uncover the optimum conditions of gene transfer, various electric field strengths and different amounts of plasmid DNA were applied. Calf muscles around the injected areas were investigated with histological methods for damage to muscle tissue. The levels of human IL-1Ra expression in the injected area and also in the serum were determined with ELISA for human IL-1Ra. Based on these data, the effects of electrotransfer of plasmid DNA were tested using the murine CIA model. DBA/1 mice were immunized with bovine collagen type II at the base of the tail. On day 21, mice were given a booster injection with the same antigen. Mice were divided into two groups on day 26. One group of mice received plasmid containing the IL-1Ra cDNA sequence, while control mice were given plasmid lacking the IL-1Ra coding sequence. The incidence of arthritis was evaluated by macroscopic analysis, histological analysis, and the levels of inflammatory cytokines. RESULTS: IL-1Ra expression increased as a function of the electrical field strength and the amount of DNA. 200 V/cm (eight pulses; 20 ms per pulse; 1 Hz) and 15 microg of plasmid DNA per mouse were found to be optimum for gene transfer. After in vivo electroporation, gene expression in both muscle and serum increased gradually, reaching a peak value on day 10. Significant levels of human IL-1Ra expression were maintained for 20 days. Macroscopic analysis showed that the onset of CIA was significantly inhibited by direct electrotransfer of plasmid DNA encoding human IL-1Ra. Histological analysis of knee joints showed that the incidence of arthritis in knee joints was also prevented. The levels of mouse IL-1beta and IL-12 in paws were significantly lower in the group treated with IL-1Ra than those in the control group. CONCLUSIONS: These results demonstrate that direct electrotransfer of plasmid containing the human IL-1Ra cDNA sequence to skeletal muscle can reduce the incidence of CIA in mice.     

Deficiency of Bax and Bak protects photoreceptors from light damage in vivo

Photoreceptors of bax(-/-)bak(-/-) but neither bax(-/-) mice nor bak(-/-) mice are protected from developmental apoptosis, suggesting that bax(-/-)bak(-/-) photoreceptors may also be protected from pathologic apoptosis. To test this possibility, we exposed bax(-/-)bak(-/-) and bax(-/-) mice to bright light, which normally induces photoreceptor death. Photoreceptors in bax(-/-)bak(-/-) mice were protected from death compared to bax(-/-) mice as indicated by a reduction in the number of TUNEL-positive photoreceptor nuclei 24 h following light damage and almost complete preservation of photoreceptors 7 days following light damage. These results provide the first in vivo evidence that combined deficiency of Bax and Bak can rescue cells from a pathologic stimulus more effectively than Bax deficiency and suggest that combined deficiency of Bax and Bak may also protect cells from other insults.     

Proteomic analysis of the response of Arabidopsis chloroplast proteins to high light stress

Light is an essential environmental factor in the progression of plant growth and development but prolonged exposure to high levels of light stress can cause cellular damage and ultimately result in the death of the plant. Plants can respond defensively to this stress for a limited period and this involves changes to their gene expression profiles. Proteomic approaches were therefore applied to the study of the response to high light stress in the Arabidopsis thaliana plant species. Wild-type Arabidopsis was grown under normal light (100 micromol photons.m(-2).s(-1)) conditions and then subjected to high light (1000 micromol photons.m(-2).s(-1)) stress. Chloroplasts were then isolated from these plants and both soluble and insoluble proteins were extracted and subjected to two-dimensional (2-D) gel electrophoresis. The resolved proteins were subsequently identified by matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS) and comparative database analysis. 64 protein spots, which were identified as candidate factors that responded to high light stress, were then selected for analysis and 52 of these were successfully identified using MALDI-TOF-MS analysis. 35 of the 52 identified proteins were found to decrease their expression levels during high light stress and a further 14 of the candidate proteins had upregulated expression levels under these conditions. Most of the proteins that were downregulated during high light stress are involved in photosynthesis pathways. However, many of the 14 upregulated proteins were identified as previously well-known high light stress-related proteins, such as heat shock proteins (HSPs), dehydroascorbate reductase (DHAR), and superoxide dismutase (SOD). Three novel proteins that were more highly expressed during periods of high light stress but had no clear functional relationship to these conditions, were also identified in this study.     

Predictors of mortality of patients with acute respiratory failure secondary to chronic obstructive pulmonary disease admitted to an intensive care unit: A one year study

Background

Patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) commonly require hospitalization and admission to intensive care unit (ICU). It is useful to identify patients at the time of admission who are likely to have poor outcome. This study was carried out to define the predictors of mortality in patients with acute exacerbation of COPD and to device a scoring system using the baseline physiological variables for prognosticating these patients.

Methods

Eighty-two patients with acute respiratory failure secondary to COPD admitted to medical ICU over a one-year period were included. Clinical and demographic profile at the time of admission to ICU including APACHE II score and Glasgow coma scale were recorded at the time of admission to ICU. In addition, acid base disorders, renal functions, liver functions and serum albumin, were recorded at the time of presentation. Primary outcome measure was hospital mortality.

Results

Invasive ventilation was required in 69 patients (84.1%). Fifty-two patients survived to hospital discharge (63.4%). APACHE II score at the time of admission to ICU {odds ratio (95 % CI): 1.32 (1.138–1.532); p < 0.001} and serum albumin (done within 24 hours of admission) {odds ratio (95 % CI): 0.114 (0.03-0.432); p = 0.001}. An equation, constructed using the adjusted odds ratio for the two parameters, had an area under the ROC curve of 91.3%. For the choice of cut-off, sensitivity, specificity, positive and negative predictive value for predicting outcome was 90%, 86.5%, 79.4% and 93.7%.

Conclusion

APACHE II score at admission and SA levels with in 24 hrs after admission are independent predictors of mortality for patients with COPD admitted to ICU. The equation derived from these two parameters is useful for predicting outcome of these patients.     

Markers of small cell lung cancer

Lung cancer is the number one cause of cancer death; however, no specific serum biomarker is available till date for detection of early lung cancer. Despite good initial response to chemotherapy, small-cell lung cancer (SCLC) has a poor prognosis. Therefore, it is important to identify molecular markers that might influence survival and may serve as potential therapeutic targets. The review aims to summarize the current knowledge of serum biomarkers in SCLC to improve diagnostic efficiency in the detection of tumor progression in lung cancer. The current knowledge on the known serum cytokines and tumor biomarkers of SCLC is emphasized. Recent findings in the search for novel diagnostic and therapeutic molecular markers using the emerging genomic technology for detecting lung cancer are also described. It is believed that implementing these new research techniques will facilitate and improve early detection, prognostication and better treatment of SCLC.