Mitochondrial nutrients stimulate performance and mitochondrial biogenesis in exhaustively exercised rats

The aim of this study was to investigate the effects of a combination of nutrients on physical performance, oxidative stress and mitochondrial biogenesis in rats subjected to exhaustive exercise. Rats were divided into sedentary control (SC), exhaustive exercise (EC) and exhaustive exercise with nutrient supplementation (EN). The nutrients include (mg/kg/day): R-α-lipoic acid 50, acetyl-L-carnitine 100, biotin 0.1, nicotinamide 15, riboflavin 6, pyridoxine 6, creatine 50, CoQ10 5, resveratrol 5 and taurine 100. Examination of running distances over the 4-week period revealed that EN rats ran significantly longer throughout the entire duration of the exhaustive exercise period compared with the EC rats. Nutrient supplementation significantly inhibited the increase in activities of alanine transaminase, lactate dehydrogenase and creatine kinase, reversed increases in malondialdehyde, inhibited decreases in glutathione S-transferase and total antioxidant capacity in plasma, and suppressed the elevation of reactive oxygen species and apoptosis in splenic lymphocytes. Nutrient supplementation increased the protein expression of mitochondrial complexes I, II and III, mtDNA number and transcription factors involved in mitochondrial biogenesis and fusion in skeletal muscle. These findings suggest that mitochondrial nutrient supplementation can reduce exhaustive exercise-induced oxidative damage and mitochondrial dysfunction, thus leading to enhancement of physical performance and of fatigue recovery.

Laser Induced Avalanche Ionization and Electron-Lattice Heating of Silicon with Intense Near IR Femtosecond Pulses

A two temperature finite difference model has been developed and is used to describe the response of materials under ultrafast femtosecond laser pulses in the energy regime where melting and vaporization can occur. In applying this model to silicon it is observed that, for 800 nm light, laser pulse intensities that are just sufficient to achieve threshold for vaporization are also at the level of optical electric field strength where electron avalanche breakdown at the surface of the material can occur. For sub-picosecond pulses the physical response of the material is associated with a strongly temperature dependent coupling coefficient connecting electron and phonon thermal distributions. The results of these analyses demonstrate that a very thin near solid density plasma, caused by avalanche ionization, is responsible for the surface heating and subsequent thermodynamic response of the material. This interpretation is consistent throughout the pulse duration range from 80 femtoseconds to 0.2 nanoseconds. The proposed mechanism for absorption, at the near infra-red wavelength being used here, is very different from the types of mechanisms usually considered for nanosecond laser heating of semiconductors. Surface damage threshold is determined by atomic force microscopy and the threshold for plasma optical emission by photomultiplier detection . Melt deths are probed with SIMS impurity diffusion profiles and high resolution cross sectional TEM.

Femtosecond Laser Deposition of Diamond-Like Carbon Films

We have deposited unhydrogenated diamond-like carbon (DLC) films with 100 femtosecond laser pulses, at intensities in the 3x1014 - 6.5x1015 W/cm2 range. Film surface topography, optical property, and bonding structure were examined, respectively, with atomic force microscopy (AFM), spectroscopie ellipsometry (SE) and Raman spectrometry. The femtosecond pulse generated plasma was studied through time-of-flight (TOF) experiment. The most probable kinetic energy of carbon ions was estimated to be in the 300 – 2000 eV range, increasing with laser intensity. In addition, a unique ‘suprathermal’ component with kinetic energy ranging from 4 to 40 keV was observed in the TOF spectrum. This high energy peak is believed to originate from fast ions in a solid density plasma created during the absorption of each femtosecond laser pulse.

Streptococcus mutans strains recovered from caries-active or caries-free individuals differ in sensitivity to host antimicrobial peptides

Antimicrobial peptides (AMPs) are among the repertoire of host innate immune defenses. In the oral cavity, several AMPs are present in saliva and have antimicrobial activities against oral bacteria, including Streptococcus mutans, a primary etiological agent of dental caries. In this study, we hypothesized that unique S. mutans strains, as determined by DNA fingerprinting from sixty 13-year-old subjects with or without experience of caries, would have different susceptibilities to α-defensins-1-3 (HNP-1-3), β-defensins-2-3 (HBD-2-3) and LL-37. The salivary levels of these peptides in subjects were also measured by enzyme-linked immunosorbent assays. We found that S. mutans strains from children with active caries showed greater resistance to salivary HNP-1-2, HBD-2-3 and LL-37 at varying concentrations than those from caries-free subjects. In addition, combinations of these peptides increased their antimicrobial activity against S. mutans either additively or synergistically. The salivary levels of these peptides were highly variable among subjects with no correlation to host caries experience. However, the levels of a number of these peptides in saliva appeared to be positively correlated within an individual. Our findings suggest that the relative ability of S. mutans to resist host salivary AMPs may be considered a potential virulence factor for this species such that S. mutans strains that are more resistant to these peptides may have an ecological advantage to preferentially colonize within dental plaque and increase the risk of dental caries.

Changes in gene expression after phencyclidine administration in developing rats: a potential animal model for schizophrenia

Repeated administration of phencyclidine (PCP), an N-methyl-d-aspartate (NMDA) receptor antagonist, during development, may result in neuronal damage that leads to behavioral deficits in adulthood. The present study examined the potential neurotoxic effects of PCP exposure (10mg/kg) in rats on postnatal days (PNDs) 7, 9 and 11 and the possible underlying mechanism(s) for neurotoxicity. Brain tissue was harvested for RNA extraction and morphological assessments. RNA was collected from the frontal cortex for DNA microarray analysis and quantitative RT-PCR. Gene expression profiling was determined using Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Based on criteria of a fold-change greater than 1.4 and a P-value less than 0.05, 19 genes including NMDAR1 (N-methyl-d-aspartate receptor) and four pro-apoptotic genes were up-regulated, and 25 genes including four anti-apoptotic genes were down-regulated, in the PCP-treated group. In addition, the schizophrenia-relevant genes, Bdnf (Brain-derived neurotrophic factor) and Bhlhb2 (basic helix-loop-helix domain containing, class B, 2), were significantly different between the PCP and the control groups. Quantitative RT-PCR confirmed the microarray results. Elevated neuronal cell death was further confirmed using Fluoro-Jade C staining. These findings support the hypothesis that neurodegeneration caused by PCP occurs, at least in part, through the up-regulation of NMDA receptors, which makes neurons possessing these receptors more vulnerable to endogenous glutamate. The changes in schizophrenia-relevant genes after repeated PCP exposure during development may provide important information concerning the validation of an animal model for this disorder.

Isolation and characterization of a xanthan-degrading Microbacterium sp. strain XT11 from garden soil

AIMS

Isolation and characterization of the xanthan-degrading Microbacterium sp. XT11.

METHODS AND RESULTS

The bacterial isolate XT11, capable of fragmenting xanthan, has been isolated from soil sample. Morphological and biochemical analyses, as well as 16S rRNA gene sequence comparisons, demonstrated that strain XT11 should be grouped in the genus Microbacterium, and represented a new member in this family. Xanthan could be degraded by the xanthan-degrading enzyme released from strain XT11. It has been shown that xantho-oligosaccharides fragmented from xanthan had both elicitor activity and antibacterial effect against Xanthomonas campestris pv. campestris.

CONCLUSIONS

The xanthan-degrading enzyme produced by the newly isolated XT11 could fragment xanthan to form oligosaccharides.

SIGNIFICANCE AND IMPACT OF THE STUDY

Xanthan-degrading products would be useful for potential application in the control of black rot of cruciferous plants caused by X. campestris pv. campestris and, as an oligosaccharide elicitor, in making these plants resistant to disease.

Describing Adequacy of Cure with Maximum Hardness Ratios and Non-linear Regression

Redefined hardness ratios, based on extended cure intervals and maximum hardness when used in conjunction with non-linear regression, provide a readily available and accurate characterization of the curing performance of LCU-composite combinations, which is superior to the use of traditional per-specimen hardness ratios. It is recommended that the light curing guidelines provided to clinicians should be based on this more accurate description of curing behavior.

The Inhibitory Effect of MI Paste, Fluoride and a Combination of Both on the Progression of Artificial Caries-like Lesions in Enamel

It is important to evaluate the inhibitory effect on lesion progression of CPP-ACP when delivered in a mousse vehicle, commercially known as MI Paste, and compare it to actual remineralization products already established.

The Effect of Energy Application Sequence on the Microtensile Bond Strength of Different C-factor Cavity Preparations

Light curing of resin composites in high C-factor cavity preparations using a high irradiance energy application sequence may lead to decreased bond strength. However, the high irradiance energy application sequence did not result in lower bond strengths in lower C-factor cavity preparations.

Action mechanisms and structure-activity relationships of PI3Kgamma inhibitors on the enzyme: a molecular modeling study

Action mechanisms of four types of PI3Kgamma inhibitors were investigated on the ligand-binding pocket (LBP) of PI3Kgamma with molecular modeling method. At first five compounds whose complex structures with PI3Kgamma were available experimentally were used to validate the reliability of docking program Autodock3.0. The results demonstrated that the program could reproduce the bound conformations of those compounds in crystal structures. Then the program was used to dock all the four types of PI3Kgamma inhibitors into the LBP of the enzyme. The predicted activities of these compounds were in agreement with their experimental activities, and a pharmacophore model was hence derived for these compounds, which consisted of one hydrophobic portion flanked by two symmetric hydrophilic portions. Furthermore, the structure-activity relationships of PI3Kgamma inhibitors were elucidated and the activity differences between them were discussed.

Appropriate use of personal protective equipment among healthcare workers in public sector hospitals and primary healthcare polyclinics during the SARS outbreak in Singapore

BACKGROUND

Singapore was affected by an outbreak of severe acute respiratory syndrome (SARS) from 25 February to 31 May 2003, with 238 probable cases and 33 deaths.

AIMS

To study usage of personal protective equipment (PPE) among three groups of healthcare workers (HCWs: doctors, nurses, and administrative staff), to determine if the appropriate PPE were used by the different groups and to examine the factors that may determine inappropriate use.

METHODS

A self-administered questionnaire survey of 14,554 HCWs in nine healthcare settings, which included tertiary care hospitals, community hospitals, and polyclinics, was carried out in May-July 2003. Only doctors, nurses, and clerical staff were selected for subsequent analysis.

RESULTS

A total of 10 236 valid questionnaires were returned (70.3% response); 873 doctors, 4404 nurses, and 921 clerical staff were studied. A total of 32.5% of doctors, 48.7% of nurses, and 77.1% of the administrative staff agreed that paper and/or surgical masks were "useful in protecting from contracting SARS". Among this group, 23.6% of doctors and 42.3% of nurses reported working with SARS patients. The view that a paper and/or surgical mask was adequate protection against SARS was held by 33.3% of doctors and 55.9% of nurses working at the A&E unit, 30.5% of doctors and 49.4% of nurses from medical wards, and 27.5% of doctors and 37.1% of nurses from intensive care units. Factors which predicted for agreement that paper and/or surgical masks were protective against SARS, included HCW's job title, reported contact with SARS patients, area of work, and Impact Events Scale scores.

CONCLUSION

A variety of factors determine appropriate use of personal protective equipment by HCWs in the face of a major SARS outbreak.

Resin-dentin interfacial ultrastructure and microtensile dentin bond strength after five-year water storage

OBJECTIVE

To evaluate a total-etch three-step adhesive system's resin-dentin interfacial ultrastructure and microtensile dentin bond strength (microTBS) after multi-year storage in water.

METHODS

Resin composite crowns were formed on 600 grit SiC flattened extracted human molars using a total-etch three-step adhesive system (Optibond FL, Kerr) and a hybrid resin composite (Prodigy, Kerr). microTBS specimens were fabricated and placed in water with 0.5% chloramine T at 37 degrees C until respective static load to failure testing at one-month, six-months and five-year storage. Failure modes were determined by scanning electron microscopy. The interfacial ultrastructure of the resin-dentin interface was analyzed by transmission electron microscopy (TEM) at 48-hours and 44-months storage. microTBS was modeled with Weibull distribution for survival analysis and failure curve distributions were analyzed by the Wald chi-square statistic for significant differences at alpha=0.05.

RESULTS

The characteristic tensile strength (sigma omicron) at one-month, six-months and five-year storage was 52.63, 14.77 and 23.57 Mpa, with a Weibull modulus of 3.04, 1.56 and 1.28, respectively. Failure distributions for all groups were significantly different (p<0.0001) with one-month > five-year > six-months. TEM interfacial morphology demonstrated hydrolytic degradation of hybrid layer components at 44-months storage.

SIGNIFICANCE

The decrease in tensile strength and changes in ultrastructure may be caused by water sorption and resultant hydrolytic degradation of the adhesive joint.

[Induced expression of the variable region of AMA-1 from Plasmodium falciparum]

OBJECTIVE

To express the variable region of AMA-1 gene from Plasmodium falciparum in Escherichia coli.

METHODS

Genomic DNA of FCC1/HN was used as template and the variable region of AMA-1 gene was amplified by polymerase chain reaction(PCR). The PCR products were digested by endonuclease BamH I and Hind III, cloned into pBlu2KSP. The nucleotide sequences of the variable region of AMA-1 gene were determined by sequencing. The AMA-1 gene fragment was subcloned into plasmid pQE, expressed in E. coli and induced by IPTG. The fusion product as identified by SDS-PAGE gel electrophoresis and Western blotting were proceeded with anti-AMA-1 sera from rabbit.

RESULTS

The size of the variable region of AMA-1 gene from FCC1/HN was 506 bp and encoded 168 amino acids. On SDS-PAGE gel dyed with Coomassie brilliant blue R250, no specific protein band can be discerned, but Western blotting proceeded with anti-AMA-1 sera from rabbit demonstrated that the specific protein band was about 23.0 kDa.

CONCLUSION

The variable region of AMA-1 gene from FCC1/HN was able to be expressed in E. coli and analysis of Western blotting demonstrated that the AMA-1 fussion protein contained specific antigenic epitopes.

[Inducible expression of MSP1 gene of Plasmodium falciparum by a tetracycline-controlled promoter]

OBJECTIVE

To express the entire MSP1 gene of Plasmodium falciparum and its C-terminal 42 kDa fragment using a tetracycline-controlled PLtetO-1 promoter.

METHODS

The entire MSP1 gene and 42 kDa fragment gene were cloned into the plasmid of pZE11, and transformed into E. coli DH5 alpha Z1. Restriction enzyme analysis, SDS-PAGE and Western blotting were used to examine two recombinant plasmids and their expression in E. coli DH5 alpha Z1.

RESULTS

The recombinant plasmids of pZE11/MSP1 and pZE11/MSP1-42 were constructed successfully. The expressive products about 190 kDa and 42 kDa of two genes in E. coli DH5 alpha Z1 were identified by SDS-PAGE and Western blotting.

CONCLUSION

Tightly controlling expression of the MSP1 gene in E. coli is essential to reduce the toxicity of the product to its host cells as well as to provide a feasibility to construct Salmonella vaccine strain which can inducibly express the important malarial vaccine candidate gene.

Biochemical characterization of bona fide polycystin-1 in vitro and in vivo

The most common form of autosomal dominant polycystic kidney disease (PKD) results from mutation of the PKD1 gene on chromosome 16p13.3. The gene encodes a 14-kb messenger RNA that is predicted to express a 462-kd membrane protein. The gene product, polycystin-1, has a large extracellular portion composed of a novel combination of protein-protein interacting domains and is postulated to be a plasma membrane receptor involved in cell-cell/matrix interactions. However, slow progress has been made in the characterization of polycystin-1 or the determination of its function. In fact, the protein is expressed at very low levels in tissues and cell lines and previous efforts directed at expression of recombinant protein had been largely unsuccessful. We have recently developed constructs of full-length human PKD1 complementary (cDNA) that can be expressed in both a stable and transient fashion in mammalian cells. We used these systems to characterize our antibodies and to track the protein in vivo. We report here the first biochemical characterization of recombinant polycystin-1 and show that the protein is a 520-kd glycosylated polypeptide with an unglycosylated core of 460 kd. Subcellular fractionation as well as biotinylation studies confirmed that the protein is plasma-membrane associated. Furthermore, we show that the recombinant protein localizes to cell-cell junctions in polarized madin darby canine kidney cells as revealed by indirect immunofluorescence. Our data represent the first characterization of polycystin-1 performed under highly controlled conditions.

Study of the frequency response of the thin film cold cathode electron source of a lighting element

Details of the recent experimental and theoretical studies of the frequency characteristic of the field emission electron source of a lighting element are given. The response times at different frequencies (0.02-200 kHz) and applied gap fields, acting on cathode surface, have been studied. A correlation has been found to exist between the response time and the frequency of applied voltage pulse. The response time remains almost constant within a range of frequencies between 1 and 30 kHz, and it remains nearly constant with increasing applied gap field higher than the threshold field. Finally, the cutoff frequency of the electron source is found, and with the current design of the electron source, it can be as high as 40 kHz. An equivalent circuit model is proposed, and theoretical results based on this model agree well with experimental findings.

BAFF-R, a newly identified TNF receptor that specifically interacts with BAFF

B cell homeostasis has been shown to critically depend on BAFF, the B cell activation factor from the tumor necrosis factor (TNF) family. Although BAFF is already known to bind two receptors, BCMA and TACI, we have identified a third receptor for BAFF that we have termed BAFF-R. BAFF-R binding appears to be highly specific for BAFF, suggesting a unique role for this ligand-receptor interaction. Consistent with this, the BAFF-R locus is disrupted in A/WySnJ mice, which display a B cell phenotype qualitatively similar to that of the BAFF-deficient mice. Thus, BAFF-R appears to be the principal receptor for BAFF-mediated mature B cell survival.