Thyroid and hypoxic stress in the newt Triturus carnifex

When specimens of the newt Triturus carnifex, under anaesthesia by submersion in a 0.2% chlorbutol solution for 25 min, are isolated in a respiratory chamber at 18 degrees C containing water with only 1.3 ppm of oxygen, they consume the oxygen completely in about 3 hr, but they can stay alive for many more hours and wake up with no apparent exterior consequences. Hypoxia induces rapid onset of hepatic steatosis and melanosis, as well as a controlled haemolytic process involving a pool of red blood cells of the same order of size as that held as a reserve in the spleen by animals in an aerial habitat. At the origin of the phenomena is an intense response by the hypophysis, histologically detectable 1 hr from the onset of treatment and confirmed 2 hr later by a highly significant increase in the plasma thyroidstimulating hormone (TSH) concentration compared with the controls (41.5 +/- 13.7 microU/L vs. 15.5 +/- 6.2; P < 0.005). The thyroid follicles react by reabsorbing their colloid, but instead of an increase in the plasma free T3 and T4 concentrations, fT3 falls significantly (1.5 +/- 0.3 pg/mL vs., the 2.4 +/- 0.7; P < 0.05), whereas fT4 remains stationary (4.0 +/- 0.5 pg/mL vs. 4.6 +/- 0.8; N.S.). After 6 hr, the plasmatic TSH concentration is still higher than in the controls (27.0 +/- 3.0 microU/L vs. 15.5 +/- 6.2; P < 0.05), whereas fT3 and fT4 remain stable (1.5 +/- 0.3 and 4.4 +/- 0.5 pg/mL, respectively). If T3 or T4 labelled with 125I is administered prior to hypoxia, after 6 hr of treatment the radioactivity is found to be limited exclusively to the liver and kidney; the thyroid, gall bladder and gut result negative, and this does not agree with hypotheses of hormone inactivation by deiodination, sulphation or glucuronidation. This apparently peculiar endocrine path has not been observed in previous studies on hypoxia in vertebrates, because the experiments were always designed to analyse plasma hormone levels after at least 24 hr of hypoxia or during chronic treatments, losing the most interesting phases of the endocrine response. The possibility that the hypoxic newt possesses alternative or complementary metabolic pathways to anaerobic glycolysis to sustain steatogenesis and melanogenesis and maintain the same cardiac activity as the controls is briefly discussed.     

High-performance liquid chromatographic determination of the magnetic resonance imaging contrast agent Gadocoletate ion in human plasma, urine and faeces

Gadocoletate ion is a new paramagnetic intravascular contrast agent for magnetic resonance imaging (MRI). An high-performance liquid chromatographic method for assaying Gadocoletate ion in human plasma, urine and faecal samples is described. The analysis is based on the reversed-phase chromatographic separation of Gadocoletate ion from the endogenous components of the biological matrices and its detection during elution by ultraviolet light absorption at 200 nm. The selectivity of the method was satisfactory. The mean absolute recovery during the analytical sample preparation was greater than 87%. The precision, expressed as coefficient of variation (CV%) ranged from 0.29 to 5.90% and the accuracy, expressed as mean relative error (R.E.%) of the analytical method ranged from -3.7 to +7.1%. The detection limit in plasma and urine was 2.01 and 10.0 microg/mL (0.00203 and 0.0101 micromol/mL), respectively. The detection limit in homogenized faecal samples was 17.7 microg/g (0.0179 micromol/g). Stability studies were performed in human plasma and urine samples during the analytical cycle. Gadocoletate ion was shown to be stable in human plasma and in human urine when stored at about +4 degrees C for up 24 h, and after three freeze-thaw cycles. In addition, it was shown to be stable in samples of processed plasma and in diluted urine at about +4 degrees C for 48 h, and at room temperature for at least 24 h. As regards the long-term stability of Gadocoletate ion, the results of dedicated studies showed that Gadocoletate ion is stable in human plasma samples when stored at +4 degrees C for up to 30 days and at -80 degrees C for up to 90 days. Gadocoletate ion is stable in samples of human urine when stored at +4 degrees C for up to 30 days, and when stored at -20 degrees C and at -80 degrees C for up to 90 days. The method has been successfully validated in human plasma, urine and faeces and it has been shown to be precise, accurate and reliable.     

Dehydration,rehydration, and overhydration alter patterns of gene expression in the Antarctic midge, <Emphasis Type="Italic">Belgica antarctica</Emphasis>

We investigated molecular responses elicited by three types of dehydration (fast, slow and cryoprotective), rehydration and overhydration in larvae of the Antarctic midge, Belgica antarctica. The larvae spend most the year encased in ice but during the austral summer are vulnerable to summer storms, osmotic stress from ocean spray and drying conditions due to wind and intense sunlight. Using suppressive subtractive hybridization (SSH), we obtained clones that were potentially responsive to dehydration and then used northern blots to evaluate the gene’s responsiveness to different dehydration rates and hydration states. Among the genes most responsive to changes in the hydration state were those encoding heat shock proteins (smHsp, Hsp70, Hsp90), antioxidants (superoxide dismutase, catalase), detoxification (metallothionein, cytochrome p450), genes involved in altering cell membranes (fatty acid desaturase, phospholipase A2 activating protein, fatty acyl CoA desaturase) and the cytoskeleton (actin, muscle-specific actin), and several additional genes including a zinc-finger protein, pacifastin and VATPase. Among the three types of dehydration evaluated, fast dehydration elicited the strongest response (more genes, higher expression), followed by cryoprotective dehydration and slow dehydration. During rehydration most, but not all, genes that were expressed during dehydration continued to be expressed; fatty acid desaturase was the only gene to be uniquely upregulated in response to rehydration. All genes examined, except VATPase, were upregulated in response to overhydration. The midge larvae are thus responding quickly to water loss and gain by expressing genes that encode proteins contributing to maintenance of proper protein function, protection and overall cell homeostasis during times of osmotic flux, a challenge that is particularly acute in this Antarctic environment.     

Contrasting Effects of GA3 Treatments on Tomato Plants Exposed to Increasing Salinity

The role of plant hormones under saline stress is critical in modulating physiological responses that will eventually lead to adaptation to an unfavorable environment. Nevertheless, the functional level of plant hormones, and their relative tissue concentration, may have a different impact on plant growth and stress tolerance at increasing salinity of the root environment. Vigorous plant growth may counteract the negative effects of salinization. In contrast, low gibberellin (GA) levels have been associated with reduced growth in response to salinity. Based on these facts and considering that the physiological basis of the cause-effect relationship between functional growth control and stress adaptation/survival is still a matter of debate, we hypothesized that exogenous applications of the plant hormone GA₃ may compensate for the salt-induced growth deficiency and consequently facilitate tomato plant adaptation to a saline environment. GA₃ application (0 or 100 mg GA₃ l⁻¹) was compared under four salinity levels, obtained by adding equal increments of NaCl:CaCl₂ (2:1 molar basis) (EC = 2.5, 6.8, 11.7, 16.7 dS m⁻¹) to the nutrient solution. GA₃ treatment reduced stomatal resistance and enhanced plant water use at low salinity. These responses were associated with an increased number of fruit per plant at harvest. However, moderate and high salinity nullified these differences. The fruit carotenoid level was generally lower in GA₃-treated plants, indicating either an inhibitory effect of GA₃ treatment on carotenoid biosynthesis or a reduced perception of the stress environment by GA₃-treated tomato plants.     

A spectroelectrochemical and chemical study on oxidation of 7,8-dihydroxy-4-methylcoumarin (DHMC) and some related compounds in aprotic medium

Electrochemical and chemical oxidation of 7,8-hydroxy-4-methylcoumarin (DHMC 1) and 7,8-diacetoxy-4-methylcoumarin (DAMC 4) were studied to investigate the mechanisms occurring in their antioxidant activities in acetonitrile, under electron transfer and H-atom transfer conditions. Electrolysis and chemical reactions were followed on-line by monitoring the UV spectral changes with time.     

Cross-linking of the mannose receptor on monocyte-derived dendritic cells activates an anti-inflammatory immunosuppressive program

Immature monocyte-derived dendritic cells (DC) strongly express the endocytic mannose receptor (MR). Addition of a specific anti-MR mAb (clone PAM-1) for 24 h to cultures of immature DC induced phenotypical and functional maturation of the cells, assessed as up-regulation of costimulatory molecules and CD83, and chemotactic response to CCL19. A different isotype-matched anti-MR mAb (clone 19.2) had no significant effect. Engagement of MR with mAb PAM-1 induced the production of the anti-inflammatory cytokines IL-10, IL-1R antagonist, and of the nonsignaling IL-1R type II. In contrast IL-1beta, TNF, and IL-12 were not produced. PAM-1-treated DC were unable to polarize Th1 effector cells and did not secrete the chemokines CXCL10 and CCL19; in turn, they produced large amounts of CCL22 and CCL17, thus favoring the amplification of Th2 circuits. T cells cocultured with PAM-1-matured DC initially proliferated but later became anergic and behaved as suppressor/regulatory cells. Natural ligands binding to MR had differential effects. MUC III (a partially purified mucin), biglycan (a purified complex proteoglycan), and mannosylated lipoarabinomannan from Mycobacterium tuberculosis affected cytokine production with high IL-10, IL-1R antagonist, IL-1R type II, and inhibition of IL-12. In contrast, mannan, dextran, and thyroglobulin had no significant effect. In conclusion, the appropriate engagement of the MR by mAb PAM-1 and selected natural ligands elicit a secretory program in mono-derived DC characterized by a distinct profile of cytokines/chemokines with the ability to dampen inflammation and to inhibit the generation of Th1-polarized immune responses.     

Role of plasma phosphorylated neurofilament heavy chain (pNfH) in amyotrophic lateral sclerosis

The phosphorylated neurofilament heavy chain (pNfH) is a promising biomarker in amyotrophic lateral sclerosis (ALS). We examined plasma pNfH concentrations in order to corroborate its role as a diagnostic and prognostic biomarker in ALS. Incident ALS cases enrolled in a population‐based registry were retrospectively selected and matched by sex and age with a cohort of healthy volunteers. Plasma pNfH levels were measured by an ELISA kit and correlated with clinical parameters. Discrimination ability of pNfH was tested using receiving operating characteristic (ROC) curves. Kaplan–Meier (KM) analysis and Cox proportional hazard models were used for survival analysis. Plasma pNfH was significantly higher in patients compared to controls. An optimal cut‐off of 39.74 pg/ml discriminated cases from controls with an elevated sensitivity and specificity. Bulbar‐onset cases had higher plasma pNfH compared to spinal onset (p = 0.0033). Furthermore, plasma pNfH positively correlated with disease progression rate (r = 0.19, p = 0.031). Baseline plasma pNfH did not influence survival in our cohort. Our findings confirmed the potential utility of plasma pNfH as a diagnostic biomarker in ALS. However, further studies with longitudinal data are needed to corroborate its prognostic value.     

Community isolation drives lower fish biomass and species richness,but higher functional evenness,in a river metacommunity

1. The flow of individuals among communities and their interactions with local environmental filters are increasingly recognised as determinants of biodiversity patterns in riverine ecosystems. Both incoming dispersers and local conditions are expected to systematically change along connectivity gradients from headwaters to downstream communities. However, the interplay between isolation-centrality gradients and environmental conditions as determinants of biodiversity structure and function has seldom been considered.
2. Here, we represented the dendritic structure of the Negro River basin riverscape (Uruguay) in a directed graph quantifying the isolation-centrality of each river section and evaluated the direct and indirect pathways by which riverscape structure and environmental local drivers determine fish community assembly.
3. Fish communities (n = 58) were sampled following a stratified sampling design that properly represents this isolation-centrality connectivity gradient through the riverscape. In each community, fish abundance, biomass, richness, and functional diversity were estimated, and the direct and indirect hypothesised connections among them were evaluated with structural equation models.
4. We showed that the range of isolation among river sections determines a 2-fold, 5-fold, and 25-fold variation in total fish richness, abundance, and biomass, respectively. Additionally, isolation-centrality was positively associated with local temperature and conductivity, while negatively related to local depth. These variables and taxonomic richness accounted for most of the variation in total fish biomass (81%) herein used as measurement of ecosystem function. Local fish abundance was negatively and positively associated with functional evenness and taxonomic richness, respectively. Furthermore, once the effect of isolation on biomass and richness was accounted for, an effect of diversity on biomass became evident.
5. Our results provide empirical evidence for the role of riverscape structure on taxonomic and functional diversity, biomass, and the relationship between biodiversity and ecosystem function. We emphasise that in the understanding of river biodiversity and its management, local determinants should not be considered without attention to metacommunity processes.

     

Silver(I)-organophosphane complexes of the dihydridobis(3-nitro-1,2,4-triazolyl)borate ligand. X-ray crystal structure of {[H2B(tz)2]Ag[P(m-tolyl)3]2} with the scorpionate ligand co-ordinated in an unidentate κ-N fashion

New silver(I) complexes have been synthesised from the reaction of AgNO₃, monodentate PR₃ (PR₃ = P(o-tolyl)₃, P(m-tolyl)₃, P(p-tolyl)₃, P(p-C₆H₄F), SeP(C₆H₅)₃) or bidentate tertiary (dppe = bis(diphenylphosphane)ethane, dppf = 1,1′-bis(diphenylphosphane)ferrocene) phosphanes and potassium dihydrobis(3-nitro-1,2,4-triazolyl)borate, K[H₂B(tz^NO2)₂]. These compounds have been characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H and ³¹P) NMR spectral data. The adduct {[H₂B(tz^NO2)₂]Ag[P(m-tolyl)₃]₂} has been characterized by single crystal X-ray studies. In the former, the H₂B(tz^NO2)₂ acts as a monodentate ligand utilizing the coordinating capability of only one of the additional (exo-) ring nitrogens to complete the coordination array about the silver atom.     

Lessons from a pilot study of transfer factor in chronic fatigue syndrome

Transfer Factor (TF) was used in a placebo controlled pilot study of 20 patients with chronic fatigue syndrome (CFS). Efficacy of the treatment was evaluated by clinical monitoring and testing for antibodies to Epstein-Barr virus (EBV) and human herpes virus-6 (HHV-6). Of the 20 patients in the placebo-controlled trial, improvement was observed in 12 patients, generally within 3-6 weeks of beginning treatment. Herpes virus serology seldom correlated with clinical response. This study provided experience with oral TF, useful in designing a larger placebo-controlled clinical trial.