Multiple regulation of nucleoside catabolizing enzymes in Escherichia coli: effects of 3:5'' cyclic AMP and CRP protein.

Summary The regulation of the synthesis of nucleoside metabolizing enzymes has been studied in cya and crp mutant strains of Escherichia coli.The synthesis of the cyt-enzymes, cytidine deaminase and uridine phosphorylase regulated by the cytR gene product, is activated by the cAMP-CRP complex. On the other hand the synthesis of the deoenzymes: deoxyriboaldolase, thymidine phosphorylase, phosphodeoxyribomutase and purine nucleoside phosphorylase, appears to be increased if an active cAMP-CRP complex cannot be formed.It also seems that nucleosides serve as poor carbon sources for cya and crp mutants; this could not solely be explained by low levels of nucleoside metabolizing enzymes nor by a deficiency in nucleoside uptake. Addition of casamino acids stimulated the growth of cya and crp mutants, with nucleosides as carbon sources. When grown on glucose and casamino acids growth could be stimulated by adenine and hypoxanthine nucleosides; these results suggest an impaired nitrogen metabolism in cya and crp mutants.Abbreviations and Symbols cAMP cyclic adenosine 3:5-monophosphate - CRP cAMP receptor protein. Genes coding for: adenyl cyclase - cya cAMP receptor protein - crp cytidine deaminase - cdd uridine phosphorylase - udp thymidine phosphorylase - tpp purine nucleoside phosphorylase - pup; cytR regulatory gene for cdd, udp, dra, tpp, drm, and pup - deoR regulatory gene for dra, tpp, drm, and pup     

An in vivo method for measuring turbulence in mechanical prosthesis leakage jets

This work introduces a method for the in vivo measurement and analysis of turbulence within the leakage of a mechanical heart valve. Several analysis techniques were applied to ultrasound measurements acquired within the atrium of a pig, and error associated with these techniques was analyzed. The technique chosen applies cyclic averaging to mean and maximum velocity measurements within small, normalized phase windows to calculate Reynolds normal stresses in the direction of the ultrasound beam. Maximum shear stresses are estimated from these normal stresses using an analytical technique. The stresses observed were smaller than those reported from previous in vitro simulations.     

Failure of catecholamines to shift T-cell cytokine responses toward a Th2 profile in patients with rheumatoid arthritis

To further understand the role of neuro-immunological interactions in the pathogenesis of rheumatoid arthritis (RA), we studied the influence of sympathetic neurotransmitters on cytokine production of T cells in patients with RA. T cells were isolated from peripheral blood of RA patients or healthy donors (HDs), and stimulated via CD3 and CD28. Co-incubation was carried out with epinephrine or norepinephrine in concentrations ranging from 10(-5) M to 10(-11) M. Interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, interleukin (IL)-4, and IL-10 were determined in the culture supernatant with enzyme-linked immunosorbent assay. In addition, IFN-gamma and IL-10 were evaluated with intracellular cytokine staining. Furthermore, basal and agonist-induced cAMP levels and catecholamine-induced apoptosis of T cells were measured. Catecholamines inhibited the synthesis of IFN-gamma, TNF-alpha, and IL-10 at a concentration of 10(-5) M. In addition, IFN-gamma release was suppressed by 10(-7) M epinephrine. Lower catecholamine concentrations exerted no significant effect. A reduced IL-4 production upon co-incubation with 10(-5) M epinephrine was observed in RA patients only. The inhibitory effect of catecholamines on IFN-gamma production was lower in RA patients as compared with HDs. In RA patients, a catecholamine-induced shift toward a Th2 (type 2) polarised cytokine profile was abrogated. Evaluation of intracellular cytokines revealed that CD8-positive T cells were accountable for the impaired catecholaminergic control of IFN-gamma production. The highly significant negative correlation between age and catecholamine effects in HDs was not found in RA patients. Basal and stimulated cAMP levels in T-cell subsets and catecholamine-induced apoptosis did not differ between RA patients and HDs. RA patients demonstrate an impaired inhibitory effect of catecholamines on IFN-gamma production together with a failure to induce a shift of T-cell cytokine responses toward a Th2-like profile. Such an unfavorable situation is a perpetuating factor for inflammation.     

A rhodamine-labeled citalopram analogue as a high-affinity fluorescent probe for the serotonin transporter

A novel fluorescent ligand was synthesized as a high-affinity, high specificity probe for visualizing the serotonin transporter (SERT). The rhodamine fluorophore was extended from an aniline substitution on the 5-position of the dihydroisobenzofuran ring of citalopram (2, 1-(3-(dimethylamino)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile), using an ethylamino linker. The resulting rhodamine-labeled ligand 8 inhibited [³H]5-HT uptake in COS-7 cells (K_i = 225 nM) with similar potency to the tropane-based JHC 1-064 (1), but with higher specificity towards the SERT relative to the transporters for dopamine and norepinephrine. Visualization of the SERT with compound 8 was demonstrated by confocal microscopy in HEK293 cells stably expressing EGFP–SERT.     

Size-asymmetric root competition in deep,nutrient-poor soil

Aims There is much evidence that plant competition below ground is size symmetric, i.e. that competing plants share contested resources in proportion to their sizes. Several researchers have hypothesized that a patchy distribution of soil nutrients could result in size-asymmetric root competition. We tested this hypothesis.     

Some Observations on the Irradiance and Carbon Fixation in Grane Langsø

Photosynthetically active radiation (PAR) was registered daily in 0.25 m and 11.25 m in 3 years. Upwards irradiance of green light was 1 % of downward irradiance. Incubator ¹⁴C experiments showed that the phytoplankton enhanced its carbon uptake substantially with increasing concentrations of the carrier CO₂ in the ampoules. Severe carbon limitation of photosynthesis occurred in spring and summer 1961, where the real carbon fixation was only about 34 % of that calculated by the usual procedure. Utilization of light and DIC by the phytoplankton and its compensation depth was determined. Photoinhibition occurred down to 10–11 m, and net primary production was nearly always positive in any depth down to the lake bottom.     

Radioiodine treatment of multinodular non-toxic goitre.

OBJECTIVE--To investigate the long term effect of radioactive iodine on thyroid function and size in patients with non-toxic multinodular goitre. DESIGN--Consecutive patients with multinodular non-toxic goitre selected for radioactive iodine treatment and followed for a minimum of 12 months (median 48 months) after an intended dose of 3.7 MBq/g thyroid tissue corrected to a 100% uptake of iodine-131 in 24 hours. PATIENTS--69 patients with a growing multinodular non-toxic goitre causing local compression symptoms or cosmetic inconveniences. The treatment was chosen because of a high operative risk, previous thyroidectomy, or refusal to be operated on. MAIN OUTCOME MEASUREMENTS--Standard thyroid function variables and ultrasonically determined thyroid volume before treatment as well as 1, 2, 3, 6, and 12 months after treatment and then once a year. RESULTS--56 patients were treated with a single dose of 131I, 12 with two doses, and one with four doses. In 45 patients treated with one dose and remaining euthyroid the median thyroid volume was reduced from 73 (interquartile range 50-106) ml to 29 (23-48) ml at 24 months in the 39 patients in whom this was measured during follow up. The median reduction was 40 (22-48) ml (60% reduction, p < 0.0001), half of which occurred within three months. Patients treated with two doses as well as those developing hypothyroidism and hyperthyroidism had a significant reduction in thyroid volume. Eleven patients developed hypothyroidism (cumulative five year risk 22%, 95% confidence interval 4.8% to 38.4%). Side effects were few: three cases of hyperthyroidism and two cases of radiation thyroiditis. Only one patient was dissatisfied with the result; she was referred for operation six months after treatment. CONCLUSIONS--A substantial reduction in thyroid volume accompanied by a low incidence of hypothyroidism and few side effects makes the use of radioactive iodine an attractive alternative to surgery in selected cases of non-toxic multinodular goitre.     

Role of guanosine kinase in the utilization of guanosine for nucleotide synthesis in Escherichia coli

Using purine auxotrophic strains of Escherichia coli with additional genetic lesions in the pathways of interconversion and salvage of purine compounds, we demonstrated the in vivo function of guanosine kinase and inosine kinase. Mutants with increased ability to utilize guanosine were isolated by plating cells on medium with guanosine as the sole purine source. These mutants had altered guanosine kinase activity and the mutations were mapped in the gene encoding guanosine kinase, gsk. Some of the mutants had acquired an additional genetic lesion in the purine de novo biosynthetic pathway, namely a purF, a purL or a purM mutation. A revised map location of the gsk gene is presented and the gene order established as proC-acrA-apt-adk-gsk-purE.     

The likelihood of persistent arthritis increases with the level of anti-citrullinated peptide antibody and immunoglobulin M rheumatoid factor: a longitudinal study of 376 patients with very early undifferentiated arthritis

Introduction  

We wanted to assess the importance of the levels of anti-citrullinated peptide antibody (anti-CCP) and immunoglobulin M (IgM) rheumatoid factor (RF) in predicting development of persistent arthritis from undifferentiated arthritis (UA), and to investigate whether there is an added predictive value for persistent arthritis in testing for both anti-CCP and IgM RF.     

Changes in reproductive behavior in adult damselfly Calopteryx splendens (Odonata: Calopterygidae) in response to flood

The reproductive behavior of adult Calopteryx splendens males and females inhabiting the Nida River, south Poland, was studied and compared during a pre‐flood and a post‐flood year. The flood disturbance in 2010 caused a decrease in aquatic macrophytes, thus reducing availability of potential territories and consequently, significantly influencing male behavior towards a frequent non‐territorial strategy. Many males in the post‐flood population had damaged wings due to extremely aggressive contests. Male–male tandems were commonly observed; this is an uncommon behavior in C. splendens. Although the sex ratio was male‐biased throughout the whole study, we observed more males in the post‐flood year. We also observed less‐frequent copulations and ovipositions during the post‐flood year. The only unchanged characteristic was population density, which did not differ before and after the flood disturbance. Floods have significant impact on damselfly reproductive sites and this, due to changes in behavior and sex ratio, may result in further consequences on population dynamics.