Level Of Metabolic Activity Research Articles

Carbodiimide cross-linking of amniotic membranes in the presence of amino acid bridges.

The purpose of this study was to investigate the carbodiimide cross-linking of amniotic membrane (AM) in the presence of amino acid bridges. The biological tissues were treated with glycine, lysine, or glutamic acid and chemically cross-linked to examine the role of amino acid types in collagenous biomaterial processing. Results of zeta potential measurements showed that the use of uncharged, positively and negatively charged amino acids dictates the charge state of membrane surface. Tensile strength and water content measurements demonstrated that the addition of lysine molecules to the cross-linking system can increase the cross-linking efficiency and dehydration degree while the introduction of glutamic acid in the AM samples decreases the number of cross-links per unit mass of chemically modified tissue collagen. The differences in the cross-linking density further determined the thermal and biological stability by differential scanning calorimetry and in vitro degradation tests. As demonstrated in matrix permeability studies, the improved formation of covalent cross-linkages imposed by lysine facilitated construction of stronger cross-linking structures. In contrast, the added glycine molecules were insufficient to enhance the resistances of the proteinaceous matrices to thermal denaturation and enzymatic degradation. The cytocompatibility of these biological tissue membranes was evaluated by using human corneal epithelial cell cultures. Results of cell viability, metabolic activity, and pro-inflammatory gene expression level showed that the AM materials cross-linked with carbodiimide in the presence of different types of amino acids are well tolerated without evidence of detrimental effect on cell growth. In addition, the amino acid treated and carbodiimide cross-linked AM implants had good biocompatibility in the anterior chamber of the rabbit eye model. Our findings suggest that amino acid type is a very important engineering parameter to mediate carbodiimide cross-linking of AM collagen.

Effects of menthol on the pharmacokinetics of triazolam and phenytoin.

We have previously shown that menthol attenuates the anticoagulant effect of warfarin by increasing the expression levels of CYP3A and CYP2C in the liver. This study evaluated the effects of menthol on the pharmacokinetics of the CYP3A substrate triazolam and the CYP2C substrate phenytoin. Menthol was orally administered to mice for 7 d. Twenty-four hours after the administration of menthol, triazolam was orally administered, and the plasma concentration was measured. In addition, the CYP3A metabolic activity for triazolam and the CYP3A expression level in the liver were determined. The effects of menthol on the pharmacokinetics of phenytoin were assessed in the same manner. In the menthol-treated group, the area under the blood concentration-time curve (AUC) of triazolam was lower and its clearance was higher compared with the control group. The CYP3A metabolic activity and CYP3A expression level in the liver were significantly increased in the menthol-treated group compared with the control group. Similarly, the AUC of phenytoin was lower and the hepatic CYP2C expression level was higher in the menthol-treated group. Thus, menthol lowered the plasma concentrations of triazolam and phenytoin when concurrently administered. These effects may be attributed to an increased metabolic activity for these drugs due to the increased expression of CYP3A and CYP2C in the liver.

Metabolic Control of Ca2+/Calmodulin-dependent Protein Kinase II (CaMKII)-mediated Caspase-2 Suppression by the B55β/Protein Phosphatase 2A (PP2A)

High levels of metabolic activity confer resistance to apoptosis. Caspase-2, an apoptotic initiator, can be suppressed by high levels of nutrient flux through the pentose phosphate pathway. This metabolic control is exerted via inhibitory phosphorylation of the caspase-2 prodomain by activated Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). We show here that this activation of CaMKII depends, in part, on dephosphorylation of CaMKII at novel sites (Thr(393)/Ser(395)) and that this is mediated by metabolic activation of protein phosphatase 2A in complex with the B55β targeting subunit. This represents a novel locus of CaMKII control and also provides a mechanism contributing to metabolic control of apoptosis. These findings may have implications for metabolic control of the many CaMKII-controlled and protein phosphatase 2A-regulated physiological processes, because both enzymes appear to be responsive to alterations in glucose metabolized via the pentose phosphate pathway.

Diversity and activity of marine bacterioplankton during a diatom bloom in the North Sea assessed by total RNA and pyrotag sequencing

A recent investigation of bacterioplankton communities in the German Bight towards the end of a diatom-dominated spring phytoplankton bloom revealed pronounced successions of distinct bacterial clades. A combination of metagenomics and metaproteomics indicated that these clades had distinct substrate spectra and consumed different algal substrates. In this study we re-analyzed samples from the initial study by total community RNA (metatranscriptomics) and 16S rRNA gene amplicon sequencing. This complementary approach provided new insights into the community composition and expressed genes as well as the assessment of metabolic activity levels of distinct clades. Flavobacteria (genera Ulvibacter, Formosa, and Polaribacter), Alphaproteobacteria (SAR11 clade and Rhodobacteraceae) and Gammaproteobacteria (genus Reinekea and SAR92 clade) were the most abundant taxa. Mapping of the metatranscriptome data on assembled and taxonomically classified metagenome data of the same samples substantiated that Formosa and Polaribacter acted as major algal polymer degraders, whereas Rhodobacteraceae and Reinekea spp. exhibited less specialized substrate spectra. In addition, we found that members of the Rhodobacteraceae and SAR92 clade showed high metabolic activity levels, which suggests that these clades played a more important role during the bloom event as indicated by their in situ abundances.

Instructive nanofibrous scaffold comprising runt-related transcription factor 2 gene delivery for bone tissue engineering.

Inducer molecules capable of regulating mesenchymal stem cell differentiation into specific lineages have proven effective in basic science and in preclinical studies. Runt-related transcription factor 2 (RUNX2) is considered to be the central gene involved in the osteoblast phenotype induction, which may be advantageous for inducing bone tissue regeneration. This work envisions the development of a platform for gene delivery, combining liposomes as gene delivery devices, with electrospun nanofiber mesh (NFM) as a tissue engineering scaffold. pDNA-loaded liposomes were immobilized at the surface of functionalized polycaprolactone (PCL) NFM. Human bone-marrow-derived mesenchymal stem cells (hBMSCs) cultured on RUNX2-loaded liposomes immobilized at the surface of electrospun PCL NFM showed enhanced levels of metabolic activity and total protein synthesis. RUNX2-loaded liposomes immobilized at the surface of electrospun PCL NFMs induce a long-term gene expression of eGFP and RUNX2 by cultured hBMSCs. Furthermore, osteogenic differentiation of hBMSCs was also achieved by the overexpression of other osteogenic markers in medium free of osteogenic supplementation. These findings demonstrate that surface immobilization of RUNX2 plasmid onto elestrospun PCL NFM can produce long-term gene expression in vitro, which may be employed to enhance the osteoinductive properties of scaffolds used for bone tissue engineering strategies.

Microbial biomass and basal respiration of selected Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

Abstract. Antarctica is a unique place for soil, biological, and ecological investigations. Soils of Antarctica have been studied intensively during the last century, when different national Antarctic expeditions visited the sixth continent with the aim of investigating nature and the environment. Antarctic investigations are comprised of field surveys mainly in the terrestrial landscapes, where the polar stations of different countries are situated. That is why the main and most detailed soil surveys were conducted in the McMurdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann Hills and the Schirmacher Oasis. Our investigations were conducted during the 53rd and 55th Russian Antarctic expeditions in the base of soil pits, and samples were collected in Sub-Antarctic and Antarctic regions. Sub-Antarctic or maritime landscapes are considered to be very different from Antarctic landscapes due to differing climatic and geogenic conditions. Soils of diverse zonal landscapes were studied with the aim of assessing the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. This investigation shows that Antarctic soils are quite diverse in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as by an upper organic layer. The most developed organic layers were revealed in peat soils of King George Island, where its thickness reach, in some cases, was 80 cm. These soils as well as soils formed under guano are characterized by the highest amount of total organic carbon (TOC), between 7.22 and 33.70%. Coastal and continental Antarctic soils exhibit less developed Leptosols, Gleysols, Regolith and rare Ornhitosol, with TOC levels between 0.37 and 4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones, which can be interpreted as a result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. The soils of King George Island also have higher portions of microbial biomass (max 1.54 mg g−1) compared to coastal (max 0.26 mg g−1) and continental (max 0.22 mg g−1) Antarctic soils. Sub-Antarctic soils differ from Antarctic ones mainly by having increased organic layer thickness and total organic carbon content, higher microbial biomass carbon content, basal respiration, and metabolic activity levels.

A cisplatin-resistant head and neck cancer cell line with cytoplasmic p53(mut) exhibits ATP-binding cassette transporter upregulation and high glutathione levels.

Head and neck squamous cell carcinoma (HNSCC) cell lines with cytoplasmically sequestered mutant p53 (p53(mut_c)) are frequently more resistant to cisplatin (CDDP) than cells with mutant but nuclear p53 (p53(mut_n)). The aim of the study was to identify underlying mechanisms implicated in CDDP resistance of HNSCC cells carrying cytoplasmic p53(mut). Microarray analysis, quantitative reverse transcription polymerase chain reaction, Western blot analysis and immunocytochemistry were used to identify and evaluate candidate genes involved in CDDP resistance of p53(mut_c) cells. RNAi knockdown or treatment with inhibitors together with flow cytometry-based methods was used for functional assessment of the identified candidate genes. Cellular metabolic activity was assessed with the XTT assay, and the redox capacity of cells was evaluated by measuring cellular glutathione (GSH) levels. Upregulation of ABCC2 and ABCG2 transporters was observed in CDDP-resistant p53(mut_c) HNSCC cells. Furthermore, p53(mut_c) cells exhibited a pronounced side population that could be suppressed by RNAi knockdown of ABCG2 as well as treatment with the ATP-binding-cassette transporter inhibitors imatinib, MK571 and tariquidar. Metabolic activity and cellular GSH levels were higher in CDDP-resistant p53(mut_c) cells, consistent with a higher capacity to fend off cytotoxic oxidative effects such as those caused by CDDP treatment. Finally, ABCC2/G2 inhibition of HNSCC cells with MK571 markedly enhanced CDDP sensitivity of HNSCC cells. The observations in this study point to a major role of p53(mut_c) in conferring a stem cell like phenotype to HNSCC cells that is associated with ABCC2/G2 overexpression, high GSH and metabolic activity levels as well as CDDP resistance.

Co-Variations Among Cognition, Cerebellar Disorders and Cortical Areas With Regional Glucose-Metabolic Activities in a Homogeneous Sample with Uner Tan Syndrome: Holistic Functioning of the Human Brain

Background: Patients with Uner Tan syndrome (UTS) exhibit habitual quadrupedal locomotion (QL), intellectual disability, dysarthric speech and truncal ataxia. Examination of cognitive ability in this syndrome has not yet been demonstrated in the scientific literature. Aims: (i) To analyze the cognitive abilities of the siblings with UTS; (ii) to assess the grade of their ataxia in relation to cerebellar disorders; (iii) to measure the metabolic activities of various cerebral regions in comparison with healthy individuals; (iv) to detect the interrelationships among all of the measured variables (IQ test scores, ataxia scores, cerebro-cerebellar areas and their metabolic activity levels) to reveal the holistic activity of the brain. Methods: The Minimental State Examination (MMSE) and Wechsler Adult Intelligence Scale (WAIS-R) were applied to the affected cases and healthy subjects. Cerebellar disorders were assessed by the International Cooperative Ataxia Rating Scale (ICARS). Brain MRI scans were performed and cerebro-cerebellar areas were measured on MRI scans, including their metabolic activities (SUV), measured by positron emission tomography (PET) scanning. Results: MMSE and WAIS-R scores both correlated with cerebro-cerebellar areas. Cerebello-vermial areas and their metabolic activities were significantly smaller in patients than in normal controls; areas of the remaining structures were not significantly different between patients and healthy subjects. Brain areas significantly inter-correlated: ICARS negatively correlated with WAIS-R, MMSE scores, SUV, and cerebro-cerebellar areas, which significantly correlated with each other. Conclusions: The results suggested (i) ICARS may not only be a test for cerebellar disorders, but also may be related to global functioning of all of the cerebro-cerebellar regions; (ii) ICARS, WAIS-R and MMSE may be measures of emergent properties of the holistic activity of the brain; (iii) the psychomotor disorders in UTS may be related to decreased brain metabolism.

Examination of mechanisms (E-MECHANIC) of exercise-induced weight compensation: study protocol for a randomized controlled trial.

BackgroundWeight loss induced only by exercise is frequently less than expected, possibly because of compensatory changes in energy intake and/or energy expenditure. The purpose of the Examination of Mechanisms (E-MECHANIC) of Exercise-Induced Weight Compensation trial is to examine whether increased energy intake and/or reduced spontaneous activity or energy expenditure (outside of structured exercise) account for the less than expected, exercise-associated weight loss.Methods/DesignE-MECHANIC is a three-arm, 6-month randomized (1:1:1) controlled trial. The two intervention arms are exercise doses that reflect current recommendations for (1) general health (8 kcal/kg body weight per week (8 KKW), about 900 kcal/wk) and (2) weight loss (20 KKW, about 2,250 kcal/wk). The third arm, a nonexercise control group, will receive health information only. The sample will include a combined total of 198sedentary, overweight or obese (body mass index: ≥25 kg/m2 to ≤45 kg/m2) men and women ages 18 to 65 years. The exercise dose will be supervised and tightly controlled in an exercise training laboratory. The primary outcome variables are energy intake, which will be measured using doubly labeled water (adjusted for change in energy stores) and laboratory-based food intake tests, and the discrepancy between expected weight loss and observed weight loss. Secondary outcomes include changes in resting metabolic rate (adjusted for change in body mass), activity levels (excluding structured exercise) and body composition. In an effort to guide the development of future interventions, the participants will be behaviorally phenotyped and defined as those who do compensate (that is, fail to lose the amount of weight expected) or do not compensate (that is, lose the amount of weight expected or more).DiscussionIn this study, we will attempt to identify underlying mechanisms to explain why exercise elicits less weight loss than expected. This information will guide the development of interventions to increase exercise-induced weight loss and maximize weight loss retention and related health benefits.Trial registrationClinicalTrials.gov ID: NCT01264406 (registration date: 20 December 2010).

Cellular Toxicity of Calf Blood Extract on Human Corneal Epithelial Cells In Vitro

Purpose: To investigate the biologic effects of the calf blood extract on corneal epithelial cells in vitro.Materials and methods: The effects on corneal epithelial cells were evaluated after 1, 4, 12, and 24 h of exposure to various concentrations of calf blood extract (3, 5, 8 and 16%). The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay was performed to measure levels of cellular metabolic activity. The lactate dehydrogenase (LDH) assay was performed to determine the extent of cellular damage. Cellular morphology was examined using phase-contrast microscopy. The scratch wound assay was performed to quantify the migration of corneal epithelial cells.Results: At the 3 and 5% concentrations of calf blood extract, MTT values were similar to those observed in the control group. However, at a concentration of 8 and 16%, cellular metabolic activity was significantly decreased after 4 h of exposure to calf blood extract. After 12 h of exposure to 8 and 16% concentrations of calf blood extract, LDH activity and cellular morphological damage to the corneal epithelial cells were significantly increased. There was no evidence of cellular migration after 12 h exposure to 5% or higher concentration of calf blood extract because of cellular toxicity.Conclusions: Compared with normal corneal epithelial cells, the cellular activity was decreased, and toxicity was increased after over 12 h of exposure to more than 5% concentration of calf blood extract. Further clinical studies will be necessary to determine the optimal concentration and exposure time for the topical application of eye drops containing calf blood extract.

Butyryl‐CoA transferase DNA abundance is not correlated with butyrate production of the intestinal microbial community in piglets with short‐bowel syndrome (SBS) (LB370)

The objective of this study was to examine the relationship between microbial composition, gene abundance, and corresponding short‐chain fatty acid (SCFA) concentration in piglets with SBS fed pre‐ and/or probiotics. We hypothesized that prebiotic consumption would increase the abundance of butyrogenic bactria, butyryl‐CoA transferase DNA (BCoAT), and butyrate concentration while attenuating acetogens, acetyl‐CoA synthase DNA (ACS), and acetate concentration. Neonatal piglets (n=70) underwent 80% jejunoileal resection and placement of a jugular catheter. Piglets received 80% parenteral and 20% enteral nutrition (EN) for 1, 3, or 7 days (d). Control piglets (CON) received unsupplemented EN, prebiotic (PRE) 10 g short‐chain fructooligosaccharides/L EN (scFOS), probiotic (PRO) 1E9 CFU LGG, and synbiotic (SYN) scFOS + LGG. BCoAT was increased by PRE on ileal mucosa at 7d and by PRO in ileal lumen at 3d and 7d (p=0.05). PRE increased butyrate concentration vs CON independent of time (p=0.05). However, BCoAT abundance was not correlated with butyrate concentration. ACS and acetate concentration were neither impacted by treatments nor correlated with each other. This demonstrates that SCFA production may not be regulated simply by gene abundance in the microbial community, thus regulation at the level of mRNA or metabolic activity needs study.Grant Funding Source: Supported by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Default mode network hypometabolism in epileptic encephalopathies with CSWS

Previous studies investigating cerebral metabolic changes associated with continuous spike-waves during sleep (CSWS) compared the metabolism of children with CSWS with that of healthy adults, precluding any assessment in brain areas showing physiologic age-related metabolic changes. Here, we investigated the metabolic and connectivity changes characterizing the acute phase of CSWS activity by comparing awake brain metabolism of children with CSWS with that of pediatric pseudo-controls. Positron emission tomography using [18F]-fluorodeoxyglucose (FDG-PET) was performed in 17 awake children with cryptogenic CSWS (5 girls, age: 5-11 years). Voxel-based analyses identified significant metabolic changes in CSWS patients compared with 18 pediatric pseudo-controls (12 girls, age: 6-11 years, non-CSWS focal cryptogenic epilepsy with normal FDG-PET). CSWS-induced changes in the contribution of brain areas displaying metabolic changes to the level of metabolic activity in other brain areas were investigated using pathophysiological interaction. Hypermetabolism in perisylvian regions bilaterally and hypometabolism in lateral and mesial prefrontal cortex, precuneus, posterior cingulate cortex and parahippocampal gyri characterized the acute phase of CSWS (p<0.05 FWE). No change in thalamic metabolism was disclosed. Altered functional connectivity was found between hyper- and hypometabolic regions in CSWS patients compared with pediatric pseudo-controls. This study demonstrates hypometabolism in key nodes of the default mode network (DMN) in awake patients with CSWS, in relation with a possible phenomenon of sustained remote inhibition from the epileptic foci. This hypometabolism might account for some of the acquired cognitive or behavioral features of CSWS epileptic encephalopathies. This study failed to find any evidence of thalamic metabolic changes, which supports the primary involvement of the cortex in CSWS genesis.

Effect of Cell Density on Mesenchymal Stem Cells Aggregation in RGD‐Alginate 3D Matrices under Osteoinductive Conditions

Cellular activities in 3D are differentially affected by several matrix-intrinsic and extrinsic factors. This study highlights the relevance of optimizing initial cell densities when establishing 3D cultures for specific applications. Independently of the entrapping density, MSCs cultured within RGD-alginate hydrogels showed steady-state levels of metabolic activity and were in a nearly non-proliferative state, but recovered "normal" activity levels when retrieved from 3D matrices and re-cultured as monolayers. Importantly, high-densities promoted the establishment of cell-cell contacts with formation of multicellular clusters stabilized by endogenous ECM, and also stimulated MSCs osteogenic differentiation. These MSC-ECM microtissues may be used as building blocks for tissue engineering.

Overall Assessment of Indoor Conditions in a School Building: an Italian Case Study

Current standards for indoor comfort are based on studies of adults, but they also apply tochildren, even though children differ in terms of metabolic rates, clothing types, activity levels, and preferences in space arrangement. Children are also more sensitive to a range of environmental factors, they are usually unable to interact with their environment, and they accept indoor conditions passively. This study aims to extend research into indoor environmental quality (IEQ) for children by providing analysis, measurements and surveys carried out in an Italian primary school. Continuous monitoring was combined with a detailed spot monitoring campaign, during which pupils completed a questionnaire so that subjective and objective evaluations could be compared. Thermal comfort was also evaluated by comparing pupils’ sensations based on the two most common approaches: the heat balance and adaptive comfort models. Tests revealed that there was no clear, uniform correspondence between subjective response and acoustic and thermal measurements. Children reacted actively to discomfort, suggesting that they should be allowed to interact with their environment. Building acoustics were also measured in order to evaluate the insulating properties of building elements. The following tests were conducted: facade sound insulation, sound insulation of the vertical and horizontal partitions between classrooms, and the impact levels between overlapped classrooms. Reverberation time and background noise were measured in unoccupied, furnished classrooms after school hours. Impulse response and Speech Transmission Index (STI) measurements were also performed in one classroom.

Increased precuneus connectivity during propofol sedation

Using functional magnetic resonance imaging in human participants, we show that sedation by propofol to the point of lost overt responsiveness during the performance of an auditory verbal memory task unexpectedly increases functional connectivity of the precuneus with cortical regions, particularly the dorsal prefrontal and visual cortices. After recovery of consciousness, functional connectivity returns to a pattern similar to that observed during the wakeful baseline. In the context of a recent proposal that highlights the uncoupling of consciousness, connectedness, and responsiveness in general anesthesia, the increased precuneus functional connectivity under propofol sedation may reflect disconnected endogenous mentation or dreaming that continues at a reduced level of metabolic activity.

Toxic effects of resazurin on cell cultures

Resazurin, introduced as a cell viability indicator under the trade name alamarBlue(®), is generally regarded as nontoxic when used according to manufacturer's suggested shorter-term incubation time specifications. However, problems arise when exposure times are extended to longer-term cultures on the order of days. To assess the effect of resazurin over longer incubation times, MCF7 (HTB-22), MCF10A (CRL-10317), 3T3-L1 (CL-173), and D1 (CRL-12424) cultures were tested with varying amounts of resazurin over 4- and 8-day periods. MCF7, 3T3-L1, and D1 cells cultured for 8days with 20% alamarBlue(®) had significantly less cell survivability. Specifically, levels of metabolic activity, deoxyribonucleic acid (DNA) concentration, and glucose consumption of the cell lines cultured for 8days in medium with 20% alamarBlue(®) were significantly lower (p<0.05) than metabolic activity, DNA concentration, and glucose consumption of MCF7 cells cultured for 8days in medium with no alamarBlue(®). MCF7, 3T3-L1, and D1 cells used less glucose at concentrations as low as 5%. Data also suggests the toxic effects are more pronounced in the cancerous cell line as compared to the noncancerous cells.

Pharmacogenomics and Biochemical Influences of Walnuts on Diabetic Tissue

Medicinal therapy requires careful assessment of effective treatment offering an acceptable safety over human health. This study aimed to evaluate the influence of walnuts diet on streptozotocin-induced diabetic mice. Comprehen- sive systems of biochemical markers and genomic screening were used to achieve this task. Experimental animals were divided into four groups (negative and positive control, diabetic group and diabetic group fed on walnuts diet). Diabetes was induced by i.p. injection of streptozotocin (STZ) for 3 successive days. Biomarkers assay, gene expression analysis, comet assay, quantitation of DNA fragmentation and micronucleus assay were investigated. The results suggested that walnuts could act as diabetic therapy without adverse effects at metabolic activity and molecular levels in diabetic mice.

Genomic and Metabolic Preparation of Muscle in Sockeye SalmonOncorhynchus nerkafor Spawning Migration

Prolonged endurance exercise and fasting are two major metabolic challenges facing Pacific salmon during spawning migrations that often occur over 1,000 km. Because both prolonged exercise and fasting stimulate the oxidation of lipids, particularly in heavily recruited tissues such as muscle, we sought to investigate the regulatory mechanisms that establish and maintain the capacity for substrate oxidation at four separate locations during the final 750 km of nonfeeding migration in sockeye salmon Oncorhynchus nerka. Transcript levels of multiple genes encoding for important regulators of lipid, carbohydrate, and protein oxidation as well as the activity of several important enzymes involved in lipid and carbohydrate oxidation were examined in red and white muscle. We found in both muscle types that the messenger RNA (mRNA) expression of carnitine palmitoyltransferase I isoforms, peroxisome proliferator-activated receptors α and β, and adenosine monophosphate-activated protein kinase β1 were all significantly higher at the onset compared to later stages of nonfeeding migration. However, the activities of β-hydroxyacyl-CoA dehydrogenase and citrate synthase were higher only early in migration and only in red muscle. Later in the migration and as muscle lipid stores were greatly depleted, the mRNA levels of hexokinase I and aspartate aminotransferase increased in white muscle. Overall, at the onset of migration, high transcript and metabolic enzyme activity levels in skeletal muscle of sockeye salmon may help support the high rates of lipid oxidation needed for endurance swimming. Furthermore, we suggest that the muscle capacity to use carbohydrates and proteins may be adjusted throughout migration on an as-needed basis to fuel burst exercise through very difficult hydraulic passages in the river and perhaps during mating activities.

Surface-dependent cytotoxicity on bacteria as a model for environmental stress of halloysite nanotubes

This study examined the cytotoxicity of halloysite nanotubes (HNTs) by investigating physiological responses of Escherichia coli, from cell growth to protein expression. Surfaces of HNTs were modified by amine functionalization (NH2-HNTs) or bovine serum albumin (BSA) coating and their cytotoxicity levels were compared with that of non-modified HNTs (Bare-HNTs). Bare- and NH2-HNTs exhibited accelerated cell death rates at ≥0.5 mg/ml of HNTs. It was also found that concentration as low as 0.01 mg/ml of HNTs exerted significant toxic effects on the bacterial cells. Cellular viability, metabolic activity, and DNA replication all decreased with increasing concentrations of Bare- and NH2-HNTs. In contrast, 0.01 mg/ml of BSA-coated HNTs (BSA-HNTs) coated showed no evidence of cytotoxicity. Even at concentrations ≤0.1 mg/ml, the cytocompatibility of BSA-HNTs was significantly better than those of Bare- and NH2-HNTs, which was confirmed by the observation of (i) the same or similar levels of cell proliferation and cell viability to the control, and (ii) higher levels of metabolic activity and plasmid DNA replication than those of Bare- and NH2-HNTs. In addition, higher ranaspumin-2 protein yield was observed from bacterial culture supplemented with BSA-HNTs (100, 83, and 80 % of yield at 0.01, 0.05, and 0.1 mg/ml, respectively, relative to the control). This work showed that the increase of bacterial cytotoxicity of HNTs correlated well with elevating HNT concentration and that surface modification of HNTs with amine functional group and BSA coating was an effective strategy to reduce cytotoxicity up to 0.1 mg/ml of HNTs.

P53 Selectively Regulates Developmental Apoptosis of Rod Photoreceptors

Retinal cells become post-mitotic early during post-natal development. It is likely that p53, a well-known cell cycle regulator, is involved in regulating the genesis, differentiation and death of retinal cells. Furthermore, retinal cells are under constant oxidative stress that can result in DNA damage, due to the extremely high level of metabolic activity associated with phototransduction. If not repaired, this damage may result in p53-dependent cell death and ensuing vision loss. In this study, the role of p53 during retinal development and in the post-mitotic retina is investigated. A previously described super p53 transgenic mouse that expresses an extra copy of the mouse p53 gene driven by its endogenous promoter is utilized. Another transgenic mouse (HIP) that expresses the p53 gene in rod and cone photoreceptors driven by the human interphotoreceptor retinoid binding protein promoter was generated. The electroretinogram (ERG) of the super p53 mouse exhibited reduced rod-driven scotopic a and b wave and cone-driven photopic b wave responses. This deficit resulted from a reduced number of rod photoreceptors and inner nuclear layer cells. However, the reduced photopic signal arose only from lost inner retinal neurons, as cone numbers did not change. Furthermore, cell loss was non-progressive and resulted from increased apoptosis during retinal developmental as determined by TUNEL staining. In contrast, the continuous and specific expression of p53 in rod and cone photoreceptors in the mature retinas of HIP mice led to the selective loss of both rods and cones. These findings strongly support a role for p53 in regulating developmental apoptosis in the retina and suggest a potential role, either direct or indirect, for p53 in the degenerative photoreceptor loss associated with human blinding disorders.