Although infected cell O2 concentration (Oi) is known to limit respiration and nitrogenase activity in legume nodules, techniques have not been available to measure both processes simultaneously in ...an individual legume nodule. Consequently, details of the relationship between nitrogenase activity and Oi are not fully appreciated. For the present study, a probe was designed that allowed open circuit measurements of H2 evolution (nitrogenase activity) and CO2 evolution (respiration rate) in a single attached soybean nodule while simultaneously monitoring fractional oxygenation of leghemoglobin (and thereby Oi) with a nodule oximeter. Compared to measurements of whole nodulated roots, use of the probe led to inhibition of nitrogenase activity in the single nodules. During oximetry measurements, total nitrogenase activity (TNA; peak H2 evolution in Ar/O2) in the single nodules was 16% of that in whole nodulated roots and 48% of nodulated root activity when Oi was not being measured simultaneously. This inhibition did not affect the nodules' ability to regulate Oi, because exposure to Ar/O2 (80:20, v/v) caused nitrogenase activity and respiration rate to decline, and this decline was linearly correlated with a concurrent decrease in Oi. When the nodules were subsequently exposed to a linear increase in external pO2 from 20 to 100% 02 at 2.7% O2/min, fractional leghemoglobin oxygenation first increased gradually and then more rapidly, reaching saturation at a pO2 between 76 and 100% O2. Plots of nitrogenase activity and respiration rate against Oi showed that rates increased with Oi up to a value of 57 nm, with half-maximal rates being attained at Oi values between 10 and 14 nM O2. The maximum nitrogenase activity achieved during the increase in pO2 (potential nitrogenase activity) was 30 to 57% of that measured in intact nodulated roots, showing that O2 limitation of nitrogenase activity could account for a significant proportion of the inhibition of TNA associated with the use of the probe. However, some factor(s) in addition O2 must have limited the activity of single nodules at both subsaturating and saturating Oi. At Oi values greater than about 57 nM, nitrogenase activity and nodule respiration were inhibited, but, because this inhibition has been shown previously to be readily reversible when the Oi was lowered, it was not attributed to direct O2 inactivation of the nitrogenase protein. These results indicate that maximum nitrogenase activity in legume nodules is supported by a narrow range of Oi values. Possible biochemical mechanisms are discussed for both O2 limitation of nitrogenase activity at low Oi and inhibition of nitrogenase activity at high Oi.
Geosmithia
fungi are little known symbionts of bark beetles. Secondary metabolites of lilac colored species
G. lavendula
and other nine
Geosmithia
species were investigated in order to elucidate ...their possible role in the interactions of the fungi with environment. Hydroxylated anthraquinones (yellow, orange, and red pigments), were found to be the most abundant compounds produced into the medium during the submerged cultivation. Three main compounds were identified as 1,3,6,8-tetrahydroxyanthraquinone (
1
), rhodolamprometrin (1-acetyl-2,4,5,7-tetrahydroxyanthraquinone;
2
), and 1-acetyl-2,4,5,7,8-pentahydroxyanthraquinone (
3
). Compounds
2
and
3
(representing the majority of produced metabolites) inhibited the growth of G+-bacteria
Staphylococcus aureus
and
Bacillus subtilis
with minimum inhibitory concentration of 64–512 μg/mL. Anti-inflammatory activity detected as inhibition of cyclooxygenase-2 was found only for compound
3
at 1 and 10 μg/mL. Compound
2
interfered with the morphology, compound
3
with cell-cycle dynamics of adherent mammalian cell lines.
•Two new hg and one new mn complexes with the N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide ligand have been synthesized and characterized.•The importance of spodium bonding in the solid state ...of hg complexes has been demonstrated both experimentaly and theoretically.•Hirshfeld surface data analysis show a great importance of spodium bonds and metal–halogen···halogen–metal interactions.•Supramolecular assemblies and σ- -hole interactions have been studied by means of DFT calculations.
In this work we report on crystal structures of a heteroleptic coordination polymer Hg2(HL)Cl4n (1) where the nitrogen atom of the peripheral pyridine fragment is linked to another HgCl2 molecule and two discrete mononuclear heteroleptic complexes Hg(HL)I2 (2) and Mn(HL)Cl2·MeOH (3·MeOH), which were obtained through self-assembling of N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) with HgCl2, HgI2 or MnCl2, respectively. HL coordinates the HgII salts in its keto-form, while MnCl2 is chelated by a zwitterionic form of HL confirmed by the solid state IR spectroscopy. The studied here ligand molecule has a tendency to involve the 4-pyridyl nitrogen atom in coordination bonding which is correlated with the ability to transfer the electric charge and production of a zwitterionic form. The crystal structure and Hirshfeld surface data analysis show a great importance of spodium bonds and metal–halogen⋯halogen–metal interactions. A prominent consequence of lack of σ- or π-hole interactions in case of MnII ion is the isolation of metal center from the external contacts. Apart form this in 3·MeOH the halogen⋯halogen interactions are absent. It seems that the σ- or π-hole regions formed at the HgII cation in 1 and 2 favor the participation of coordinated Cl or I atoms in the M–Hal⋯Hal'–M' halogen⋯halogen interactions, whereas in complex 3·MeOH there are no metal or halogen centered σ-hole interactions. Thus, the 1D coordination polymer in 1 is stabilized by the Hg⋯Cl spodium bonding. Additionally, the observed intermolecular halogen⋯halogen interactions in 1 provide cross-linking of the 1D coordination polymers, yielding a 2D supramolecular double-layered sheet. In 2 an additional contact between halogen and mercury atoms results in a dimeric unit. These dimers are linked into a 1D polymer by halogen⋯halogen interactions between metal bounded iodine atoms. The DFT theoretical studies were applied to analyze the Hg⋯X non-covalent spodium interactions that govern the formation of the 1D polymeric structure in 1 and self-assembled dimers in 2.
This work unveils indispensable role of spodium bonding and other non-covalent interactions in the HgII-derived complexes with N'-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide, which predominantly drive formation of extended architectures in comparison to the MnII-derivative. Display omitted
Since lung volume reduction surgery (LVRS) reduces end-expiratory lung volume, we hypothesized that it may improve diaphragm strength. We evaluated 37 patients for pulmonary rehabilitation and LVRS. ...Before and 8 wk after pulmonary rehabilitation, 24 patients had spirometry, lung volumes, diffusion capacity, incremental symptom limited maximum exercise test, 6-min walk test, maximal static inspiratory and expiratory mouth pressures, and transdiaphragmatic pressures during maximum static inspiratory efforts and bilateral supramaximal electrophrenic twitch stimulation measured. Twenty patients (including 7 patients who crossed over after completing pulmonary rehabilitation) had baseline measurements postrehabilitation, and 3 mo post-LVRS. Patients were 58 +/- 8 yr of age, with severe COPD and hyperinflation (FEV1, 0.69 +/- 0.21 L; RV, 4.7 +/- 1.4 L). Nineteen patients had bilateral LVRS performed via median sternotomy and stapling, and 1 patient had unilateral LVRS via thorascopy with stapling. After rehabilitation, spirometry and DL(CO)/VA were not different, and lung volumes showed a slight worsening in hyperinflation. Gas exchange, 6-min walk distance, maximum oxygen uptake (VO2max), and breathing pattern during maximum exercise did not change after rehabilitation, but total exercise time was significantly longer. Inspiratory muscle strength (PImax, Pdi(max combined), Pdi(max sniff), Pdi(max), Pdi(twitch)), was unchanged after rehabilitation. In contrast, after LVRS, FVC increased 21%, FEV1 increased 34%, TLC decreased 13%, FRC decreased 23%, and FRC(trapped gas) and RV decreased by 57 and 28%, respectively. PCO2 was lower (44 +/- 6 versus 48 +/- 6 mm Hg, p < 0.003) and 6-min walk distance increased (343 +/- 79 versus 250 +/- 89 m, p < 0.001), as did total exercise time during maximum exercise (9.2 +/- 1.9 versus 6.9 +/- 2.7 min, p < 0.01). Minute ventilation (29 +/- 8 versus 21 +/- 6 L/min, p < 0.001) and tidal volume (1.0 +/- 0.33 versus 0.84 +/- 0.25 L, p < 0.001) during maximum exercise increased whereas respiratory rate was lower (28 +/- 6 versus 32 +/- 7 breaths/min, p < 0.02). Measurements of respiratory muscle strength (PImax, 74 +/- 28 versus 50 +/- 18 cm H2O, p < 0.002; Pdi(max combined), 80 +/- 25 versus 56 +/- 29 cm H2O, p < 0.01; Pdi(max sniff), 71 +/- 7 versus 46 +/- 27 cm H2O, p < 0.01; Pdi(twitch), 15 +/- 5 versus 7 +/- 5 cm H2O, p < 0.01) were all greater post-LVRS. Inspiratory muscle workload as measured by Pdi TTI was lower following LVRS (0.07 +/- 0.02 versus 0.09 +/- 0.03, p < 0.03). On multiple regression analysis, increases in PImax correlated significantly with decreases in RV and FRC(trapped gas) after LVRS (r = 0.67, p < 0.03). We conclude that LVRS significantly improves diaphragm strength that is associated with a reduction in lung volumes and an improvement in exercise performance. Future studies are needed to determine the relationship and stability of these changes over time.
In legume nodules the O2 in the infected cells limits respiration and nitrogenase activity, becoming more severe if nodules are exposed to subambient O2 levels. To identify the site of O2 limitation, ...adenylate pools were measured in soybean (Glycine max) nodules that were frozen in liquid N2 before being ground, lyophilized, sonicated, and separated on density gradients of nonaqueous solvents (heptane/tetrachloroethylene) to yield fractions enriched in bacteroid or plant components. In nodules maintained in air, the adenylate energy charge (AEC = ATP + 0.5 ADP/ATP + ADP + AMP) was lower in the plant compartment (0.65 ± 0.04) than in the bacteroids (0.76 ± 0.095), but did not change when the nodulated root system was exposed to 10% O2. In contrast, 10% O2 decreased the bacteroid AEC to 0.56 ± 0.06, leading to the conclusion that they are the primary site of O2 limitation in nodules. To account for the low but unchanged AEC in the plant compartment and for the evidence that mitochondria are localized in O2-enriched microenvironments adjacent to intercellular spaces, we propose that steep adenylate gradients may exist between the site of ATP synthesis (and ADP use) in the mitochondria and the extra-mitochondrial sites of ATP use (and ADP production) throughout the large, infected cells.
This report examines trends in public opinion since mid-1980. The first section describes the evolution of public perceptions concerning the terrorist threat at home and recounts Americans' ...predictions of future terrorist violence. The second section explores whether individuals have felt personally threatened by terrorism in their daily lives. The third reports the public's confidence in the government's ability to deal with the terrorist threat. The final section addresses the perceived trade-off between security and liberty since the Oklahoma City bombing and reports on public support for several governmental initiatives designed to combat such terrorism.
Performance of the cationic chiral Ru–BINAP complex in asymmetric hydrogenation of methyl-3-oxobutyrate (methylacetoacetate) in methanol was studied. Effects of temperature, pressure and the content ...of water on its activity and enantioselectivity were discussed. Attention was paid to the role of water in respect of the enhanced acetal formation in the presence of methanol. A simple approach to limit the content of acetal was introduced. The role of water addition was clarified. Tetrahydrofuran as a solvent system (with the addition of methanol or water) was also tested to minimize the acetal presence in the reaction mixture. In parallel the influence of oxygen on the catalyst stability was examined.
Stem and progenitor cells provide a promising therapeutic strategy for amyotrophic lateral sclerosis (ALS). To comparatively evaluate the therapeutic potentials of human bone marrow-derived ...mesodermal stromal cells (hMSCs) and umbilical cord blood cells (hUBCs) in ALS, we transplanted hMSCs and hUBCs and their neuroectodermal derivatives (hMSC-NSCs and hUBC-NSCs) into the ALS mouse model over-expressing the G93A mutant of the human SOD1 gene. We used a standardized protocol similar to clinical studies by performing a power calculation to estimate sample size prior to transplantation, matching the treatment groups for gender and hSOD-G93A gene content, and applying a novel method for directly injecting 100,000 cells into the CSF (the cisterna magna). Ten days after transplantation we found many cells within the subarachnoidal space ranging from frontal basal cisterns back to the cisterna magna, but only a few cells around the spinal cord. hMSCs and hMSC-NSCs were also located within the Purkinje cell layer. Intrathecal cell application did not affect survival times of mice compared to controls. Consistently, time of disease onset and first pareses, death weight, and motor neuron count in lumbar spinal cord did not vary between treatment groups. Interestingly, transplantation of hMSCs led to an increase of pre-symptomatic motor performance compared to controls in female animals. The negative outcome of the present study is most likely due to insufficient cell numbers within the affected brain regions (mainly the spinal cord). Further experiments defining the optimal cell dose, time point and route of application and particularly strategies to improve the homing of transplanted cells towards the CNS region of interest are warranted to define the therapeutic potential of mesodermal stem cells for the treatment of ALS.
Growth hormone deficiency (GHD) is associated with reduced bone mineral content and increased risk of osteoporotic fractures. Reduced peak bone mass might explain the low bone mineral density (BMD) ...among patients with childhood onset GHD (CO-GHD) whilst the cause of osteopenia in adult-onset GHD (AO-GHD) is not fully understood.
Prospective multicentric study to asses bone status in GHD adults after two years of recombinant growth hormone replacement treatment.
In 94 GHD adults (49 men; Ø 34.5 yrs) we have measured BMD and bone markers (CTX, osteocalcin) during two years of rhGH treatment (at baseline, after 3 and 6 months, and after 1 and 2 years). Patients were adequately substituted for GHD and other pituitary deficiencies.
We have observed an increase in BMD-lumbar spine: n=42, 0.8155 →0.9418 g/cm2, p<0.0001; femoral neck n=41; 0.8468 →0.9031; p= 0.0004; BMD-whole body 1.0179 →1.0774; p=0.0003. We have compared gender difference: BMD-L-spine by 15.8 % in men (n=21) and by 5.6 % in women (n=19) (p= 0.008); BMD-femoral neck increased by 11.03 % in men and by about 3.0 % in women (p=0.032). In women, the initial decrease in BMD was recorded after 3 months. CO-GHD adults yielded a higher increase in BMD -L-spine (16.6 %, p=0.022). A correlation exists between IGF-I levels and BMD in lumbar spine (1st year: R=0.348, p=0.026; 2nd year: R= 0.33, p=0.0081) and between IGF-I and osteocalcin (1st year: R=0.383; p=0.0038).
Two-year therapy with recombinant human growth hormone improved bone status. IGF-I appears to be a good indicator of rhGH effect on bone (Tab. 3, Fig. 9, Ref. 36). Text in PDF www.elis.sk.
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