Showing papers on "Low protein published in 2007"

Acute traumatic coagulopathy: initiated by hypoperfusion: modulated through the protein C pathway?

Abstract: Objectives: Coagulopathy following major trauma is conventionally attributed to activation and consumption of coagulation factors. Recent studies have identified an acute coagulopathy present on admission that is independent of injury severity. We hypothesized that early coagulopathy is due to tissue hypoperfusion, and investigated derangements in coagulation associated with this. Methods: This was a prospective cohort study of major trauma patients admitted to a single trauma center. Blood was drawn within 10 minutes of arrival for analysis of partial thromboplastin and prothrombin times, prothrombin fragments 12, fibrinogen, thrombomodulin, protein C, plasminogen activator inhibitor-1, and D-dimers. Base deficit (BD) was used as a measure of tissue hypoperfusion. Results: A total of 208 patients were enrolled. Patients without tissue hypoperfusion were not coagulopathic, irrespective of the amount of thrombin generated. Prolongation of the partial thromboplastin and prothrombin times was only observed with an increased BD. An increasing BD was associated with high soluble thrombomodulin and low protein C levels. Low protein C levels were associated with prolongation of the partial thromboplastin and prothrombin times and hyperfibrinolysis with low levels of plasminogen activator inhibitor-1 and high D-dimer levels. High thrombomodulin and low protein C levels were significantly associated with increased mortality, blood transfusion requirements, acute renal injury, and reduced ventilator-free days. Conclusions: Early traumatic coagulopathy occurs only in the presence of tissue hypoperfusion and appears to occur without significant consumption of coagulation factors. Alterations in the thrombomodulin-protein C pathway are consistent with activated protein C activation and systemic anticoagulation. Admission plasma thrombomodulin and protein C levels are predictive of clinical outcomes following major trauma.

CLINICAL-LIVER, PANCREAS, AND BILIARY TRACT Primary Prophylaxis of Spontaneous Bacterial Peritonitis Delays Hepatorenal Syndrome and Improves Survival in Cirrhosis

Abstract: Background & Aims: Norfloxacin is highly effective in preventing spontaneous bacterial peritonitis recurrence in cirrhosis, but its role in the primary prevention of this complication is uncertain. Methods: Patients with cirrhosis and low protein ascitic levels ( 9 points with serum bilirubin level > 3 mg/dL) or impaired renal function (serum creatinine level > 1.2 mg/dL, blood urea nitrogen level > 25 mg/dL, or serum sodium level < 130 mEq/L) were included in a randomized controlled trial aimed at comparing norfloxacin (35 patients) vs placebo (33 patients) in the primary prophylaxis of spontaneous bacterial peritonitis. The main end points of the trial were 3-month and 1-year probability of survival. Secondary end points were 1-year probability of development of spontaneous bacterial peritonitis and hepatorenal syndrome. Results: Norfloxacin administration reduced the 1-year probability of developing spontaneous bacterial peritonitis (7% vs 61%, P < .001) and hepatorenal syndrome (28% vs 41%, P .02), and improved the 3-month (94% vs 62%, P .003) and the 1-year (60% vs 48%, P .05) probability of survival compared with placebo. Conclusions: Primary prophylaxis with norfloxacin has a great impact in the clinical course of patients with advanced cirrhosis. It reduces the incidence of spontaneous bacterial peritonitis, delays the development of hepatorenal syndrome, and improves survival.

Double Mutants Deficient in Cytosolic and Thylakoid Ascorbate Peroxidase Reveal a Complex Mode of Interaction between Reactive Oxygen Species, Plant Development, and Response to Abiotic Stresses

Abstract: Reactive oxygen species (ROS) play a key signaling role in plants and are controlled in cells by a complex network of ROS metabolizing enzymes found in several different cellular compartments. To study how different ROS signals, generated in different cellular compartments, are integrated in cells, we generated a double mutant lacking thylakoid ascorbate peroxidase (tylapx) and cytosolic ascorbate peroxidase1 (apx1). Our analysis suggests that two different signals are generated in plants lacking cytosolic APX1 or tylAPX. The lack of a chloroplastic hydrogen peroxide removal enzyme triggers a specific signal in cells that results in enhanced tolerance to heat stress, whereas the lack of a cytosolic hydrogen peroxide removal enzyme triggers a different signal, which results in stunted growth and enhanced sensitivity to oxidative stress. When the two signals are coactivated in cells (i.e. tylapx/apx1), a new response is detected, suggesting that the integration of the two different signals results in a new signal that manifests in late flowering, low protein oxidation during light stress, and enhanced accumulation of anthocyanins. Our results demonstrate a high degree of plasticity in ROS signaling in Arabidopsis (Arabidopsis thaliana) and suggest the existence of redundant pathways for ROS protection that compensate for the lack of classical ROS removal enzymes such as cytosolic and chloroplastic APXs. Further investigation of the enhanced heat tolerance in plants lacking tylAPX, using mutants deficient in chloroplast-to-nuclei retrograde signaling, suggests the existence of a chloroplast-generated stress signal that enhances basal thermotolerance in plants.

A natively unfolded yeast prion monomer adopts an ensemble of collapsed and rapidly fluctuating structures

Abstract: The yeast prion protein Sup35 is a translation termination factor, whose activity is modulated by sequestration into a self-perpetuating amyloid. The prion-determining domain, NM, consists of two distinct regions: an amyloidogenic N terminus domain (N) and a charged solubilizing middle region (M). To gain insight into prion conversion, we used single-molecule fluorescence resonance energy transfer (SM-FRET) and fluorescence correlation spectroscopy to investigate the structure and dynamics of monomeric NM. Low protein concentrations in these experiments prevented the formation of obligate on-pathway oligomers, allowing us to study early folding intermediates in isolation from higher-order species. SM-FRET experiments on a dual-labeled amyloid core variant (N21C/S121C, retaining wild-type prion behavior) indicated that the N region of NM adopts a collapsed form similar to “burst-phase” intermediates formed during the folding of many globular proteins, even though it lacks a typical hydrophobic core. The mean distance between residues 21 and 121 was ≈43 Å. This increased with denaturant in a noncooperative fashion to ≈63 Å, suggesting a multitude of interconverting species rather than a small number of discrete monomeric conformers. Fluorescence correlation spectroscopy analysis of singly labeled NM revealed fast conformational fluctuations on the 20- to 300-ns time scale. Quenching from proximal and distal tyrosines resulted in distinct fast and slower fluctuations. Our results indicate that native monomeric NM is composed of an ensemble of structures, having a collapsed and rapidly fluctuating N region juxtaposed with a more extended M region. The stability of such ensembles is likely to play a key role in prion conversion.

The Clinical Pharmacokinetics of Escitalopram

Abstract: Escitalopram is the (S)-enantiomer of the racemic selective serotonin reuptake inhibitor antidepressant citalopram. Clinical studies have shown that escitalopram is effective and well tolerated in the treatment of depression and anxiety disorders. Following oral administration, escitalopram is rapidly absorbed and reaches maximum plasma concentrations in approximately 3–4 hours after either single-or multiple-dose administration. The absorption of escitalopram is not affected by food. The elimination half-life of escitalopram is about 27–33 hours and is consistent with once-daily administration. Steady-state concentrations are achieved within 7–10 days of administration. Escitalopram has low protein binding (56%) and is not likely to cause interactions with highly protein-bound drugs. It is widely distributed throughout tissues, with an apparent volume of distribution during the terminal phase after oral administration (Vz/F) of about 1100L. Unmetabolised escitalopram is the major compound in plasma. S-demethylcitalopram (S-DCT), the principal metabolite, is present at approximately one-third the level of escitalopram; however, S-DCT is a weak inhibitor of serotonin reuptake and does not contribute appreciably to the therapeutic activity of escitalopram. The didemethyl metabolite of escitalopram (S-DDCT) is typically present at or below quantifiable concentrations. Escitalopram and S-DCT exhibit linear and dose-proportional pharmacokinetics following single or multiple doses in the 10–30 mg/day dose range. Adolescents, elderly individuals and patients with hepatic impairment do not have clinically relevant differences in pharmacokinetics compared with healthy young adults, implying that adjustment of the dosage is not necessary in these patient groups. Escitalopram is metabolised by the cytochrome P450 (CYP) isoenzymes CYP2C19, CYP2D6 and CYP3A4. However, ritonavir, a potent inhibitor of CYP3A4, does not affect the pharmacokinetics of escitalopram. Coadministration of escitalopram 20mg following steady-state administration of cimetidine or omeprazole led to a 72% and 51% increase, respectively, in escitalopram exposure compared with administration alone. These changes were not considered clinically relevant. In vitro studies have shown that escitalopram has negligible inhibitory effects on CYP isoenzymes and P-glycoprotein, suggesting that escitalopram is unlikely to cause clinically significant drug-drug interactions. The favourable pharmacokinetic profile of escitalopram suggests clinical utility in a broad range of patients.

Practical points in urinary proteomics.

Abstract: During the proteomic era, one of the most rapidly growing areas in biomedical research is biomarker discovery, particularly using proteomic technologies. Urinary proteomics has become one of the most attractive subdisciplines in clinical proteomics, as the urine is an ideal source for the discovery of noninvasive biomarkers for human diseases. However, there are several barriers to the success of the field and urinary proteome analysis is not a simple task because the urine has low protein concentration, high levels of salts or other interfering compounds, and more importantly, high degree of variations (both intra-individual and inter-individual variabilities). This article provides step-by-step practical points to perform urinary proteome analysis, covering detailed information for study design, sample collection, sample storage, sample preparation, proteomic analysis, and data interpretation. The discussion herein should stimulate further discussion and refinement to develop guidelines and standardizat...

Cassava wastes: treatment options and value addition alternatives.

Abstract: Value addition of cassava and cassava wastes is necessitated by rapid post-harvest spoilage, deterioration, low protein content and environmental pollution caused by the effluent and the other associated wastes that poses aesthetic nuisance. Biogas plants of all sizes and varying levels of technical sophistication not only recover the energy contained in cassava wastes but also eliminate most of the animal and human health problems associated with contamination. Studies have shown the technical feasibility and nutritional desirability of converting carbohydrates and their residues into products containing a large amount of protein by means of microorganisms. Wastes transformation offers the possibility of creating marketable value-added products. There exists a great potential in the use of microorganisms such as fungi for the production of high quality feedstuffs from the abundantly available agro-industrial wastes, particularly carbohydrate residues. Cassava wastes can be processed and converted into value-added components such as methane (biogas), pig meat, ethanol, surfactant and fertilizer etc. Attention is now focused on the by-products of the anaerobic decomposition of the waste that takes place in a biodigester, which are the liquid fraction called biol and the solid fraction or biosol, which are excellent fertilizers for a variety of crops. The present review addresses the progress that has been made in each of these aspects with emphasis on the advantages of biol and biosol fertilizers. Key words: Carbohydrate residue, waste transformation, biofertilizers.

Toward a better analysis of secreted proteins: the example of the myeloid cells secretome

Abstract: The analysis of secreted proteins represents a challenge for current proteomics techniques. Proteins are usually secreted at low concentrations in the culture media, which makes their recovery difficult. In addition, culture media are rich in salts and other compounds interfering with most proteomics techniques, which makes selective precipitation of proteins almost mandatory for a correct subsequent proteomics analysis. Last but not least, the non-secreted proteins liberated in the culture medium upon lysis of a few dead cells heavily contaminate the so-called secreted proteins preparations. Several techniques have been used in the past for concentration of proteins secreted in culture media. These techniques present several drawbacks, such as coprecipitation of salts or poor yields at low protein concentrations. Improved techniques based on carrier-assisted TCA precipitation are described and discussed in this report. These techniques have been used to analyze the secretome of myeloid cells (macrophages, dendritic cells) and enabled to analyze proteins secreted at concentrations close to 1 ng/mL, thereby allowing the detection of some of the cytokines (TNF, IL-12) secreted by the myeloid cells upon activation by bacterial products.

Epigenetic Inactivation of the Chromosomal Stability Control Genes BRCA1, BRCA2, and XRCC5 in Non–Small Cell Lung Cancer

Abstract: Purpose: Lung cancer cells frequently exhibit marked chromosome instability We postulated that alterations of the double-strand break repair genes ( BRCA1, BRCA2 , and XRCC5 ) might be involved in lung cancer Patients and Methods: We examined the loss of protein and mRNA expression and the 5′CpG hypermethylation and allelic imbalance of the BRCA1, BRCA2 , and XRCC5 genes in 98 non–small cell lung cancer (NSCLC) samples Anchorage-dependent growth after reexpression of these genes was examined in a lung cancer cell line that originally lacked BRCA1 and BRCA2 expression Results: The data indicated that low protein expression of BRCA1 and BRCA2 was frequent in lung adenocarcinomas (42-44%), whereas low XRCC5 protein expression was more prevalent among squamous cell carcinoma (32%) In addition, low BRCA1 expression was significantly associated with low RB expression, especially in lung adenocarcinoma Concurrent alterations in XRCC5 and p53 were the most frequent profiles in smoking patients Importantly, low mRNA and protein expressions of BRCA1, BRCA2 , and XRCC5 were significantly associated with their promoter hypermethylation 5-Aza-2′-deoxycytidine treatment of NSCLC cells showed demethylation and reexpression of the BRCA1 and BRCA2 genes and reduced anchorage-independent growth Conclusions: Our retrospective study provides compelling evidence that low mRNA and protein expression in the BRCA1/BRCA2 and XRCC5 genes occur in lung adenocarcinoma and squamous cell carcinoma, respectively, and that promoter hypermethylation is the predominant mechanism in deregulation of these genes Alteration of the double-strand break repair pathway, perhaps by interacting with p53 and RB deregulation, is important in the pathogenesis of a subset of NSCLC

LIMPIC: a computational method for the separation of protein MALDI-TOF-MS signals from noise.

Abstract: Mass spectrometry protein profiling is a promising tool for biomarker discovery in clinical proteomics. However, the development of a reliable approach for the separation of protein signals from noise is required. In this paper, LIMPIC, a computational method for the detection of protein peaks from linear-mode MALDI-TOF data is proposed. LIMPIC is based on novel techniques for background noise reduction and baseline removal. Peak detection is performed considering the presence of a non-homogeneous noise level in the mass spectrum. A comparison of the peaks collected from multiple spectra is used to classify them on the basis of a detection rate parameter, and hence to separate the protein signals from other disturbances. LIMPIC preprocessing proves to be superior than other classical preprocessing techniques, allowing for a reliable decomposition of the background noise and the baseline drift from the MALDI-TOF mass spectra. It provides lower coefficient of variation associated with the peak intensity, improving the reliability of the information that can be extracted from single spectra. Our results show that LIMPIC peak-picking is effective even in low protein concentration regimes. The analytical comparison with commercial and freeware peak-picking algorithms demonstrates its superior performances in terms of sensitivity and specificity, both on in-vitro purified protein samples and human plasma samples. The quantitative information on the peak intensity extracted with LIMPIC could be used for the recognition of significant protein profiles by means of advanced statistic tools: LIMPIC might be valuable in the perspective of biomarker discovery.

Metabolic effects of two low protein diets in chronic kidney disease stage 4–5—a randomized controlled trial

Abstract: BACKGROUND International guidelines have not reached a complete agreement about the optimal amount of dietary proteins in chronic kidney disease(CKD). The aim of this study was to compare, with a randomized-controlled design, the metabolic effects of two diets with different protein content (0.55 vs 0.80 g/kg/day) in patients with CKD stages 4-5. METHODS Study design and sample size calculations were based on previously published experience of our group with low protein diet. The primary outcome of the study was the modification of serum urea nitrogen concentration. From 423 patients randomly assigned to the two diets 392 were analysed: 200 for the 0.55-Group and 192 for the 0.8-Group. The follow-up ranged 6-18 months. RESULTS Mean age was 61+/-18 years, 44% were women, mean eGFR was 18+/-7 ml/min/month. Three months after the dietary assignment and throughout the study period the two groups had a significantly different protein intake (0.72 vs 0.92 g/kg/day). The intention-to-treat analysis did not show any difference between the two groups. Compliance to the two test diets was significantly different (P < 0.05): 27% in the 0.55-Group and 53% in the 0.8-Group, with male gender and protein content (0.8 g/kg/day) predicting adherence to the assigned diet. The per protocol analysis, conversely, showed that serum urea nitrogen, similar at the time of randomization, significantly increased in the 0.8-Group vs 0.55-Group by 15% (P < 0.05). Serum phosphate, PTH and bicarbonate resulted similar in the two groups throughout the study. The 24 h urinary urea nitrogen significantly decreased after the first 3 months in 0.55-Group (P < 0.05), as well as the excretion of creatinine, sodium and phosphate (P < 0.05 vs baseline) and were significantly lower than the 0.8-Group. The prescription of phosphate binders, allopurinol, bicarbonate supplements and diuretics resulted significantly less frequent in the 0.55-Group (P < 0.05). CONCLUSIONS This study represents the first evidence that in CKD patients a protein intake of 0.55 g/kg/day, compared with a 0.8 g/kg/day, guarantees a better metabolic control and a reduced need of drugs, without a substantial risk of malnutrition.

Different mechanisms operating during different critical time-windows reduce rat fetal beta cell mass due to a maternal low-protein or low-energy diet.

Abstract: Adverse events during intra-uterine life may programme organ growth and favour disease later in life. In animals, protein or energy restriction during gestation alters the development of the endocrine pancreas, even though the duration of malnutrition is different. Here, we evaluate the specific effects of both diets during different periods of gestation and the mechanisms underlying the decreased beta cell mass. Pregnant Wistar rats were fed either a low-protein or a low-energy diet during the last week of gestation or throughout gestation. Fetuses and their pancreases were analysed at days 15 and 21 of gestation. The low-energy diet reduced the beta cell mass from 21-day-old fetuses by 33 or 56% when administered during the last week or throughout gestation, respectively. Fetal corticosterone levels were increased. At 15 days of fetal age, the number of cells producing neurogenin 3 (NEUROG3) or pancreatic and duodenal homeobox gene 1 (PDX-1) was reduced. Neither islet vascularisation nor beta cell proliferation was affected. The low-protein diet, in contrast, was more efficient in decreasing the fetal beta cell mass when given during the last week of gestation (−53%) rather than throughout gestation (−33%). Beta cell proliferation was decreased by 50% by the low-protein diet, independently of its duration, and islet vascularisation was reduced. This diet did not affect NEUROG3- or PDX-1-positive cell numbers. Although both diets reduced the fetal beta cell mass, the cellular mechanisms and the sensitivity windows were different. Early alteration of neogenesis due to elevated corticosterone levels is likely to be responsible for the decreased beta cell mass in low-energy fetuses, whereas impaired beta cell proliferation and islet vascularisation at later stages are implicated in low-protein fetuses.

Method for label-free detection of femtogram quantities of biologics in flowing liquid samples.

Abstract: Rapid (∼10 min) measurement of very low concentration of pathogens (∼10 cells/mL) and protein (∼fg/mL) has widespread use in medical diagnostics, monitoring biothreat agents, and in a broader context as a research method. For low-level pathogen, we currently use culture enrichment methods and, thus, rapid analysis is not possible. For low protein concentration, no direct method is currently available. We report here a novel macrocantilever design whose high-order resonant mode near 1 MHz exhibits mass detection sensitivity of 10 cells/mL for cells and 100 fg/mL for protein. The sensor is 1 × 3 mm and uses a piezoelectric layer for both actuation and sensing resonance. Sample is flowed (∼1 mL/min) past the antibody-immobilized sensor, and as antigen binds to the sensor, resonance frequency decreases in proportion to antigen concentration. The sensor showed selectivity to the pathogen even though copious nonpathogenic variant was simultaneously present.

Predicting the profile of nutrients available for absorption: from nutrient requirement to animal response and environmental impact.

Abstract: Current feed evaluation systems for dairy cattle aim to match nutrient requirements with nutrient intake at pre-defined production levels. These systems were not developed to address, and are not suitable to predict, the responses to dietary changes in terms of production level and product composition, excretion of nutrients to the environment, and nutrition related disorders. The change from a requirement to a response system to meet the needs of various stakeholders requires prediction of the profile of absorbed nutrients and its subsequent utilisation for various purposes. This contribution examines the challenges to predicting the profile of nutrients available for absorption in dairy cattle and provides guidelines for further improved prediction with regard to animal production responses and environmental pollution. The profile of nutrients available for absorption comprises volatile fatty acids, long-chain fatty acids, amino acids and glucose. Thus the importance of processes in the reticulo-rumen is obvious. Much research into rumen fermentation is aimed at determination of substrate degradation rates. Quantitative knowledge on rates of passage of nutrients out of the rumen is rather limited compared with that on degradation rates, and thus should be an important theme in future research. Current systems largely ignore microbial metabolic variation, and extant mechanistic models of rumen fermentation give only limited attention to explicit representation of microbial metabolic activity. Recent molecular techniques indicate that knowledge on the presence and activity of various microbial species is far from complete. Such techniques may give a wealth of information, but to include such findings in systems predicting the nutrient profile requires close collaboration between molecular scientists and mathematical modellers on interpreting and evaluating quantitative data. Protozoal metabolism is of particular interest here given the paucity of quantitative data. Empirical models lack the biological basis necessary to evaluate mitigation strategies to reduce excretion of waste, including nitrogen, phosphorus and methane. Such models may have little predictive value when comparing various feeding strategies. Examples include the Intergovernmental Panel on Climate Change (IPCC) Tier II models to quantify methane emissions and current protein evaluation systems to evaluate low protein diets to reduce nitrogen losses to the environment. Nutrient based mechanistic models can address such issues. Since environmental issues generally attract more funding from governmental offices, further development of nutrient based models may well take place within an environmental framework.

Amelogenin Promotes the Formation of Elongated Apatite Microstructures in a Controlled Crystallization System.

Abstract: The organic matrix in forming enamel consists largely of the amelogenin protein self-assembled into nanospheres that play a pivotal role in controlling the oriented and elongated growth of highly ordered apatitic crystals during enamel biomineralization. However, the mechanisms of amelogenin-mediated mineralization have not yet been fully elucidated. Here we report that amelogenin dramatically accelerates the nucleation kinetics by decreasing the induction time in a dose-dependent manner in a controlled constant composition (CC) in vitro crystallization system. Remarkably, at very low protein concentrations, elongated microstructures which are similar in appearance to apatitic crystals in enamel were formed at relatively low supersaturations, through interfacial structural match/synergy between structured amelogenin assemblies and apatite nanocrystallites. This heterogeneous crystallization study provides experimental evidence to support the concept that templating by amelogenin very early in the crystallization process facilitates the formation of developing enamel crystals.

From Means to QTL : The Illinois Long-Term Selection Experiment as a Case Study in Quantitative Genetics

Abstract: Divergent selection for oil and protein concentration in the corn (Zea mays L.) kernel was initiated at the University of Illinois in 1896 by C.G. Hopkins. In 2005, 106 generations of selection had been completed for high oil and 105 for high protein. Limits to selection for low oil and low protein were reached but not for high oil or high protein. Over the more than 100 yr of the existence of the program a number of attempts have been made to analyse the expriment using quantitative genetic tools. The purpose of this paper is to trace the use of quantitaive genetic techniques to analyze the result of divergent long-term selection for oil and protein, to relate results of divergent long-term selection look at the reasons for long-continued progress from selection key findings include (i) progress from selection was much greater than could have been predicted, (ii) based on bath classical quantitative genetic analysis and QTL studies, a large number of QTL are involved in control of the three traits; (iii) the number of QTL identified in a given study cannot be predicted by the magnitude of genetic variance or the divergence of the parents but is a function of the number of markers used and the number of lines evaluated; and (iv) epistasis may be an important factor in explaining long-term response to selection.

A structural perspective on copper uptake in eukaryotes

Abstract: Over a decade ago, genetic studies identified a family of small integral membrane proteins, commonly referred to as copper transporters (CTRs) that are both required and sufficient for cellular copper uptake in a yeast genetic complementation assay. We recently used electron crystallography to determine a projection density map of the human high affinity transporter hCTR1 embedded into a lipid bilayer. At 6 A resolution, this first glimpse of the structure revealed that hCTR1 is trimeric and possesses the type of radial symmetry that traditionally has been associated with the structure of certain ion channels such as potassium or gap junction channels. Representative for this particular type of architecture, a region of low protein density at the center of the trimer is consistent with the existence of a copper permeable pore along the center three-fold axis of the trimer. In this contribution, we will briefly discuss how recent structure-function studies correlate with the projection density map, and provide a perspective with respect to the cellular uptake of other transition metals.

Inhibitory effects of saikosaponin-d on CCl4-induced hepatic fibrogenesis in rats.

Abstract: AIM: To investigate the suppressive effect of saikosaponin-d (SSd) on hepatic fibrosis in rats induced by CCl4 injections in combination with alcohol and high fat, low protein feeding and its relationship with the expression of nuclear factor-κB (NF-κB), tumor necrosis factor-alpha (TNF-α) and interleukins-6 (IL-6). METHODS: Hepatic fibrosis models were induced by subcutaneous injection of CCl4 at a dosage of 3 mL/kg in rats. At the same time, rats in treatment groups were injected intraperitoneally with SSd at different doses (1.0, 1.5 and 2.0 mg/kg) once daily for 6 wk in combination with CCl4, while the control group received olive oil instead of CCl4. At the end of the experiment, rats were anesthetized and killed (except for 8 rats which died during the experiment; 2 from the model group, 3 in high-dose group, 1 in medium-dose group and 2 in low-dose group). Hematoxylin and eosin (HE) staining and Van Gieson staining were used to examine the changes in liver pathology. The levels of alanine aminotransferase (ALT), triglyeride (TG), albumin (ALB), globulin (GLB), hyaluronic acid (HA) and laminin (LN) in serum and the content of hydroxyproline (HYP) in liver were measured by biochemical examinations and radioimmuneoassay, respectively. In addition, the expression of TNF-α and IL-6 in liver homogenate was evaluated by enzyme-linked immunosorbent assay (ELISA) and the levels of NF-κBp65 and I-κBα in liver tissue were analyzed by Western blotting. RESULTS: Both histological examination and Van Gieson staining demonstrated that SSd could attenuate the area and extent of necrosis and reduce the scores of liver fibrosis. Similarly, the levels of ALT, TG, GLB, HA, and LN in serum, and the contents of HYP, TNF-α and IL-6 in liver were all significantly increased in model group in comparison with those in control group. Whereas, the treatment with SSd markedly reduced all the above parameters compared with the model group, especially in the medium group (ALT: 412 ± 94.5 IU/L vs 113.76 ± 14.91 IU/L, TG: 0.95 ± 0.16 mmol/L vs 0.51 ± 0.06 mmol/L, GLB: 35.62 ± 3.28 g/L vs 24.82 ± 2.73 g/L, HA: 42.15 ± 8.25 ng/mL vs 19.83 ± 3.12 ng/mL, LN: 27.56 ± 4.21 ng/mL vs 13.78 ± 2.57 ng/mL, HYP: 27.32 ± 4.32 μg/mg vs 16.20 ± 3.12 μg/mg, TNF-α: 4.38 ± 0.76 ng/L vs 1.94 ± 0.27 ng/L, IL-6: 28.24 ± 6.37 pg/g vs 12.72 ± 5.26 pg/g, respectively, P < 0.01). SSd also decreased ALB in serum (28.49 ± 4.93 g/L vs 37.51 ± 3.17 g/L, P < 0.05). Moreover, the expression of NF-κB p65 in the liver of treated groups was lower than that in model groups while the expression of I-κBα was higher in treated group than in model group (P < 0.01). The expression of NF-κBp65 and TNF-α had a positive correlation with the level of HA in serum of rats after treatment with CCl4 (r = 0.862, P < 0.01; r = 0.928, P < 0.01, respectively). CONCLUSION: SSd attenuates CCl4-induced hepatic fibrosis in rats, which may be related to its effects of hepato-protective and anti-inflammation properties, the down-regulation of liver TNF-α, IL-6 and NF-κBp65 expression and the increased I-κBα activity in liver.

The interactive effects of protein quality and macronutrient imbalance on nutrient balancing in an insect herbivore.

Abstract: The present study evaluates the interactive effects of protein quality and the ratio of protein to digestible carbohydrate on herbivore performance, various aspects of nutritional homeostasis (feeding and post-ingestive regulation) and food choice. In the first experiment, final-instar caterpillars of generalist-feeding African cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) were confined to one of 20 diets varying in protein:carbohydrate (P:C) ratio (35:7, 28:14, 21:21, 14:28 and 7:35) and in the quality of dietary protein (0%, 20%, 50% and 80% replacement of casein-based protein mix with the low-quality plant protein, zein). Results indicated that the negative impact of low-quality protein on survival, development and growth was amplified as the P:C ratio of the diet fell. Consumption differences were the main underlying cause of this response. The effect of low protein quality was to reduce the efficiency of nitrogen utilization and to increase the conversion rate of ingested nutrient to lipid growth, irrespective of P:C ratio. In the second experiment, caterpillars were allowed to self-compose their preferred diet, selecting between one of four high-protein diets (all 35:7, but containing 0%, 20%, 50% or 80% zein) and one of four equal-P:C-ratio diets (21:21, again containing 0%, 20%, 50% or 80% zein). Caterpillars showed a compensatory increase in their self-selected P:C intake in response to the moderate decline in protein quality of the 35:7 food. No such response was demonstrated for the insects presented with 35:7 food with the lowest protein quality. The significance of these findings is discussed within the context of herbivore food selection.

Alternative oxidase involvement in cold stress response of Arabidopsis thaliana fad2 and FAD3+ cell suspensions altered in membrane lipid composition.

Abstract: To investigate how the fatty acid composition of membrane lipids influences cell growth and mitochondrial respiration, in particular the expression and capacity of alternative oxidase (AOX), under cold stress, we used the Arabidopsis thaliana fad2 knockout and FAD3+ -overexpressing cultured cells lines affected in extrachloroplastic fatty acid desaturation activities. At 22 degrees C, fad2 mitochondria exhibited a low polyunsaturated fatty acid content and low protein to lipid ratio, while mitochondria from FAD3+ were enriched in linolenic acid and in total membrane protein. As a consequence, both mutants showed a higher membrane microviscosity than the wild type. After exposure to 9 degrees C, FAD3+ mitochondria exhibited lower microviscosity and lower rigidification upon a temperature downshift than fad2. Furthermore, the extent of reduction of cell growth and respiratiory rates in the phosphorylating state was positively related to the cold sensitivity of each cell line, being more pronounced in fad2 that in the wild type, whereas the stability of those parameters reflected the cold resistance of FAD3+. In contrast, an increase in AOX capacity was observed in the three cell lines at 9 degrees C. These inductions were correlated to AOX protein amounts and seem to result from an accumulation of AOX1c transcripts in the three cell lines and of AOX1a transcripts in wild-type and fad2 cells. The fact that there is no direct relationship between the degree of cold tolerance of each cell line and their ability to enhance their AOX capacity suggests that the participation of AOX in the response of Arabidopsis cells to cold stress does not necessarily favor cold tolerance.