Synthesis of Nickel(I)-Bromide Complexes via Oxidation and Ligand Displacement: Evaluation of Ligand Effects on Speciation and Reactivity.

Nickel's +1 oxidation state has received much interest due to its varied and often enigmatic behavior in increasingly popular catalytic methods. In part, the lack of understanding about NiI results from common synthetic strategies limiting the breadth of complexes that are accessible for mechanistic study and catalyst design. We report an oxidative approach using tribromide salts that allows for the generation of a well-defined precursor, [NiI(COD)Br]2, as well as several new NiI complexes. Included among them are complexes bearing bulky monophosphines, for which structure-speciation relationships are established and catalytic reactivity in a Suzuki-Miyaura coupling (SMC) is investigated. Notably, these routes also allow for the synthesis of well-defined monomeric t-Bubpy-bound NiI complexes, which has not previously been achieved. These complexes, which react with aryl halides, can enable previously challenging mechanistic investigations and present new opportunities for catalysis and synthesis.

Catalyst Deactivation of a Monoligated CyJohnPhos-bound Nickel(0) Complex.

Cross-coupling catalysts are prone to unproductive side reactivity that can limit their practical use in synthetic chemistry. A detailed understanding of these pathways and the conditions that enable them is important for reaction optimization and rational catalyst design. In this work, we report the off-cycle reactivity of a monoligated, CyJohnPhos-bound Ni0 complex following product-forming reductive elimination. In the absence of substrate, free phosphine ligand, or π-accepting additives, dimerization of (CyJohnPhos)Ni0 occurs, followed by C-P bond activation of the ligand to form a phosphido-bridged Ni0/NiII dimer; both the Ni0/Ni0 and Ni0/NiII dimers were structurally characterized. Monomeric (CyJohnPhos)Ni0 must be intercepted by substrate or free ligand to prevent irreversible dimerization and catalyst deactivation.

Nitrogen Source Regulation of Growth and Photosynthesis in Beta vulgaris L.

Sugar beets (Beta vulgaris L. cv F58-554H1) were grown hydroponically in a 16-h light, 8-h dark period at a photosynthetic photon flux density of 0.5 mmol m-2 s-1 for 4 weeks in half-Hoagland culture solution containing only nitrate-nitrogen. Half of the plants were then transferred to half-Hoagland solution with ammonium-nitrogen (7.35mM), while the other half continued on 7.5 mM nitrate. Growth analysis was carried out by sampling the plants at 3-d intervals over a period of 21 d. Compared to plants supplied with nitrate, ammonium initially slowed the growth of shoots more than roots. Ammonium reduced both the area expansion of individual leaves and the relative water content of these leaves, but increased the amount of dry matter/area. The increase in specific leaf weight in ammonium-grown leaves was associated with a doubling of chloroplast volume, as much as a 62% rise in chlorophyll content, and a 4.3-fold higher accumulation of soluble protein. Ammonium nutrition substantially decreased the rate of expansion of photosynthetic (leaf) surface but did not decrease the rate of photosynthesis per area; in fact, net photosynthetic CO2 exchange rates were slightly higher than in nitrate plants, due to the build-up in stromal enzymes of the Calvin cycle, several of which increased in total extractable activity on a leaf area basis, e.g. ribulose-1,5- biphosphate carboxylase oxygenase, sedoheptulose-1,7-biphosphatase. Nitrogen source had no effect on stomatal conductance. Rates of photosynthesis per chlorophyll were decreased slightly in ammonium-grown leaves, possibly due to an increased CO2-diffusion resistance associated with the enlarged chloroplasts.

Carbon, Nitrogen, and Nutrient Interactions in Beta vulgaris L. as Influenced by Nitrogen Source, NO3- versus NH4+

Sugar beets (Beta vulgaris L. cv F58-554H1) were grown hydroponically in a 16-h light, 8-h dark period (photosynthetic photon flux density of 0.5 mmol m-2 s-1) for 4 weeks from sowing in half-strength Hoagland nutrient solution containing 7.5 mM nitrate. Half of the plants were then transferred to 7.5 mM ammonium N; the rest remained in solution with 7.5 mM nitrate N. Upon transfer from nitrate to ammonium, the total N concentration decreased sharply in the fibrous roots and petiole/midribs and increased substantially in the leaf blades. This was because of the decreased nitrate concentrations in fibrous roots and petioles and a concomitant increase in amino acid/amide-N and protein N in leaf blades. Sugar beets acclimated to ammonium partly by a 2.5-fold increase in glutamine synthase activity in fibrous roots and a 1.7-fold increase in leaf blades. Rapid ammonium assimilation into glutamine consumed carbon skeletons, leading to a depletion of foliar starch, sucrose, and maltose. Ammonium treatment stimulated activities of some glycolytic/Krebs cycle enzymes, e.g. pyruvate dehydrogenase. Nitrate-fed leaf blades contained substantially larger concentrations of osmolytes (i.e. nitrate, cations, and sucrose), which may have contributed to the faster rates of leaf expansion in nitrate-fed compared to ammonium-fed plants.

A comparison of the safety, efficacy, and distribution of ceforanide and cephalothin in coronary artery bypass graft surgery.

Antibiotic prophylaxis in open-heart operations is a widely accepted practice. Introduction of new antibiotics with differences in tissue distribution, spectrum of activity and therapeutic index prompts their evaluation as possible effective prophylactic agents. We compared the distribution, clinical efficacy, and safety of ceforanide with cephalothin as a prophylactic agent in coronary artery bypass graft (CABG) procedures. The results indicated that the intravenous administration of ceforanide at the dose of 1 gm every 12 hours for 2.5 days was equivalent to cephalothin 1 gm every 6 hours for 2.5 days. Serum, muscle, and bone concentrations of ceforanide were significantly greater than those of cephalothin. These concentrations consistently exceeded the minimal inhibitory concentration for Staphylococcus aureus, the major pathogen implicated in wound infections. No toxicty was observed with either antibiotic. Ceforanide merits consideration as a prophylactic antibiotic in CABG operations.

Cytosolic aldolase is a ripening related enzyme in strawberry fruits (Fragaria x ananassa).

Two aldolase isoenzymes have been isolated from ripe strawberry fruits (Fragaria x ananassa cv. Camarosa and Elsanta) and partially purified by DEAE anion exchange and Sephacryl size exclusion chromatography. The isoenzymes were identified as class I cytosol and plastid aldolase on the basis of their chromatographic behavior on DEAE-cellulose columns, native molecular weight, pH optimum pattern, Km value for D-fructose-1,6-bisphosphate, tendency to be inactivated by lower pH values and SDS-PAGE subunit determination of 40 and 38 kDa, respectively. Total aldolase activity and distribution of both aldolase isoenzymes was also investigated at different stages of strawberry fruit ripening. Strawberries in the green and white ripening stage showed the same ratio of the two isoenzymes as green leaves with 15 and 8% cytosol aldolase activity, respectively. During strawberry fruit development the overall total aldolase activity decreased until the pink ripening stage and then increased due to a rise of cytosol aldolase yielding up to 75% in red strawberries. A cDNA putatively encoding the cytosolic form of aldolase in strawberry was cloned during the course of this study. Both microarray and RNA gel blot analyses showed that the cytosolic aldolase gene expression is induced during ripening as detected for the cytosolic aldolase enzyme. We suggest that induction of the cytosolic aldolase both at the levels of transcription and translation might be part of a ripening related stress response in the receptacle tissue.

Effects of interfering and influencing factors on the analyses of p105 (c-erbB-2/HER-2) oncoprotein fragment in serum.

BACKGROUND: The 105 kDa extracellular domain of c-erbB-2 encoded protein p185 is detectable in serum. Elevated p105 serum levels were found in patients with breast and ovarian cancer and in pregnancy. The effects of interfering and influencing factors on the measurement are still unclear. MATERIAL AND METHODS: We used an ELISA based on the monoclonal capture antibody OD-3 and investigated possible interfering factors, like changing transporting and storing conditions of blood and serum samples. In order to evaluate a normal range of p105 serum values we examined 71 healthy women. RESULTS: In our tests we found no influence on the reproducibility of results by changing transporting and storing conditions. We could not find any dependency of p105 serum values on the menstrual cycle or the age of controls. Postmenopausal women showed significantly higher serum values than premenopausal women (p = 0.0127). CONCLUSIONS: Clinical interpretation of female p105 serum values requires comparison with normal ranges when considering the menopause as an influencing factor.

Comparison of ceftriaxone and cefazolin prophylaxis against infection in open heart surgery.

One hundred four patients undergoing elective open heart surgery were enrolled in a prospective, double-blind trial comparing prophylaxis against infection using a single 1 g dose of ceftriaxone and seven doses of cefazolin. Patients in both groups had similar risk factors for infection. The likelihood of achieving a tissue concentration in excess of the minimal inhibitory concentration for Staph. aureus was significantly greater with ceftriaxone in atrial appendage (p less than 0.001), muscle (p less than 0.01), and bone (p less than 0.01) than with cefazolin. The serum half-life of ceftriaxone was approximately 15.7 hours. All 49 serum samples obtained 18 to 24 hours after delivery of ceftriaxone and 26 of 33 samples obtained 40 to 48 hours after delivery had drug concentrations in excess of 3.1 micrograms/ml, the mean minimal inhibitory concentration for isolates of Staph. aureus. Early and late infectious complications were infrequent and occurred at similar rates in both groups. Neither drug was associated with significant toxicity. A single 1 g dose of ceftriaxone was as effective and safe as multiple doses of cefazolin and demonstrated superior tissue penetration.

Visualizing rhizosphere chemistry of legumes with mid-infrared synchrotron radiation.

A bright synchrotron light source operated by the Lawrence Berkeley National Laboratory served as an external source for infrared (IR) microscopy of plant root microcosms. Mid-IR light from synchrotrons is 2-3 orders of magnitude brighter than conventional sources, providing contrast based on the chemical information in the reflected signal at a spatial resolution near the diffraction-limit of 3-10 microm. In an experiment using plant root microcosms fitted with zinc selenide IR-transmissive windows (50 mm x 20 mm x 1 mm), we describe chemical differences and similarities within the root zone of mung bean (Vigna radiata L.), grown with or without phosphorus, and revealed by reflectance spectromicroscopy. Comparative root and root-exudate profiles are described in sand/silt culture over the wavelength range of 2.5 to 16 pm (4.000 to 650 cm(-1) ) in the mid-IR. the spectral region most useful for the analytical identification of small organic molecules. Root epidermal tissue of plants grown with low phosphorus showed a greater lipid contribution and less lignin than nutrient-sufficient plants. In the zone 200 microm from the root axis, control plants were enriched with simple sugars and monomeric lignin precursors. In low-phosphorus plants, the rhizosphere possessed IR signatures from protein and sugars. Individual soil minerals could be easily discriminated from biological material. Synchrotron IR spectromicroscopy, therefore, complements existing root imaging techniques.

Effects of phosphorus nutrition on photosynthesis in Glycine max (L.) Merr.

The effects of phosphorus nutrition on various aspects of photosynthetic metabolism have been examined for soybean plants (Glycine max) grown in growth chambers. Orthophosphate was supplied at two levels in 0.5-strength Hoagland's solution. At the end of the 19-d growth period, plants grown at 10 µM KH2PO4 (low-P plants) had undergone a 40% drop in net CO2 exchange (averaged over a 16-h light period), as compared with control plants grown with 200 µM KH2PO4. Low-P resulted in reductions in the initial activities of five, and in the total activities of seven, Calvin-cycle enzymes. Notable exceptions were the initial and total activities of chloroplastic fructose-1,6-bisphosphatase (EC 3.1.3.11) which were increased by 85 and 53%, respectively, by low-P. Low-P decreased leaf 3-phosphoglycerate (PGA) levels most (by 80%), ribulose-1,5-bis-phosphate (RuBP) less (by 47%) while triose-phosphate (TP) was not significantly changed. The results indicate that photosynthetic CO2-fixation in low-P plants was limited more by RuBP regeneration than by ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) activity. Ribulose-1,5-bisphosphate regeneration in low-P plants did not appear to be limited by ATP and-or NADPH supply because ATP/ADP and NADPH/ NADP(+) ratios were increased by 60 and 37%, respectively, by low-P, and because TP/PGA ratios were higher in low-P plants. Low-P may diminish RuBP regeneration, and hence photosynthesis, by reducing Calvin-cycle enzyme activity, in particular, the initial activity of ribulose-5-phosphate kinase (EC 2.7.1.19) (44% reduction), and by enhancing the flux of carbon into starch biosynthesis.

Single-dose antimicrobial prophylaxis in open heart surgery.

A single one-gram pre-operative dose of ceftriaxone was compared with seven one-gram doses of cefazolin administered peri-operatively with the aim of preventing infections associated with coronary artery bypass graft surgery. Ninety-four evaluable cases were analyzed; 49 patients received ceftriaxone and 45 received cefazolin. There was no significant difference in the number of infectious complications between the two groups. Ceftriaxone had a terminal half-life of approximately 15.7 hours. There was no toxicity associated with either antibiotic. Because of the reduced number of doses, single-dose prophylaxis may result in considerable savings. Single-dose prophylaxis with ceftriaxone was found to be an effective modality for prevention of infection in open heart surgery.

EGF-R and overexpression of the oncogene c-erbB-2 in ovarian cancer: immunohistochemical findings and prognostic value.

PURPOSE: The purpose of this study was to investigate the prognostic value of EGF-R (c-erbB-1) compared to the overexpression of the c-erbB-2 oncogene product p185 in ovarian cancer. PATIENTS AND METHODS: The study was conducted on 266 previously untreated ovarian cancer patients with FIGO stage I-IV disease. EGF-R and c-erbB-2 oncogene product p185 have been evaluated using immunohistochemistry. Survival times were analyzed according to the method described by Kaplan and Meier. For the simultaneous evaluation of the prognostic relevance of the analyzed factors, a Cox proportional hazards regression was performed. RESULTS: EGF-R was detected in 13%, and c-erbB-2 oncogene product p185 in 18% of primary tumors. EGF-R showed no significant impact on the survival time, whereas c-erbB-2 oncogene product p185 positive patients had a significantly worse prognosis compared to p185 negative cases (p = 0.002). In the multivariate analysis, c-erbB-2 oncogene product p185, like tumor stage, histological grade and age, was found to be a significant prognostic factor. CONCLUSION: These data confirm the prognostic importance of the c-erbB-2; oncogene product p185 in ovarian cancer at the time of primary surgery, while EGF-R does not seem to have prognostic relevance.

Genetic dissection of plant cell-wall biosynthesis.

The plant cell wall is a complex structure consisting of a variety of polymers including cellulose, xyloglucan, xylan and polygalacturonan. Biochemical and genetic analysis has made it possible to clone genes encoding cellulose synthases (CesA). A comparison of the predicted protein sequences in the Arabidopsis genome indicates that 30 divergent genes with similarity to CesAs exist. It is possible that these cellulose synthase-like (Csl) proteins do not contribute to cellulose synthesis, but rather to the synthesis of other wall polymers. A major challenge is, therefore, to assign biological function to these genes. In an effort to address this issue we have systematically identified T-DNA or transposon insertions in 17 Arabidopsis Csls. Phenotypic characterization of "knock-out" mutants includes the determination of spectroscopic profile differences in mutant cell walls from wild-type plants by Fourier-transform IR microscopy. A more precise characterization includes cell wall fractionation followed by neutral sugar composition analysis by anionic exchange chromatography.