Electrochemical Arylation Reaction

Arylated products are found in various fields of chemistry and represent essential entities for many applications. Therefore, the formation of this structural feature represents a central issue of contemporary organic synthesis. By the action of electricity the necessity of leaving groups, metal catalysts, stoichiometric oxidizers, or reducing agents can be omitted in part or even completely. The replacement of conventional reagents by sustainable electricity not only will be environmentally benign but also allows significant short cuts in electrochemical synthesis. In addition, this methodology can be considered as inherently safe. The current survey is organized in cathodic and anodic conversions as well as by the number of leaving groups being involved. In some electroconversions the reagents used are regenerated at the electrode, whereas in other electrotransformations free radical sequences are exploited to afford a highly sustainable process. The electrochemical formation of the aryl-substrate bond is discussed for aromatic substrates, heterocycles, other multiple bond systems, and even at saturated carbon substrates. This survey covers most of the seminal work and the advances of the past two decades in this area.

A solvent-directed stereoselective and electrocatalytic synthesis of diisoeugenol

A stereoselective and electrocatalytic coupling reaction of isoeugenol has been demonstrated for the first time, wherein 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) plays a crucial role.

Unexpected high robustness of electrochemical cross-coupling for a broad range of current density

Electro-organic synthesis is a powerful technique for the sustainable preparation of compounds. However, many electrosynthetic reactions require complex equipment, are limited to a very narrow current density range, or have very long reaction times; some also involve nonselective transformations and bad scalability. The robust and selective synthesis of nonsymmetric biphenols and partially protected derivatives is established by anodic C-C cross-coupling. The setup is simple, involving constant current conditions and undivided cells. Its key is a unique electrolyte system based on fluorous alcohols and mixtures, particularly 1,1,1,3,3,3-hexafluoroisopropanol. This allows variations of the current density of more than two orders of magnitude without decreasing selectivity or product yield. This exceptional effect is unknown for electro-organic synthesis of products that have similar oxidation potentials as the starting materials. It potentially paves the way for industrial electrolyzers with variable current consumption, which could enable the flexible use of energy surplus in the electricity supply.

Dynamic Precision Phenotyping Reveals Mechanism of Crop Tolerance to Root Herbivory

The western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) is a major pest of maize (Zea mays) that is well adapted to most crop management strategies. Breeding for tolerance is a promising alternative to combat WCR but is currently constrained by a lack of physiological understanding and phenotyping tools. We developed dynamic precision phenotyping approaches using ¹¹C with positron emission tomography, root autoradiography, and radiometabolite flux analysis to understand maize tolerance to WCR Our results reveal that WCR attack induces specific patterns of lateral root growth that are associated with a shift in auxin biosynthesis from indole-3-pyruvic acid to indole-3-acetonitrile. WCR attack also increases transport of newly synthesized amino acids to the roots, including the accumulation of Gln. Finally, the regrowth zones of WCR-attacked roots show an increase in Gln turnover, which strongly correlates with the induction of indole-3-acetonitrile-dependent auxin biosynthesis. In summary, our findings identify local changes in the auxin biosynthesis flux network as a promising marker for induced WCR tolerance.

Morphological organization of neuropile glial cells in the central nervous system of the medicinal leech (Hirudo medicinalis)

Neuropile glial (NPG) cells in the central nervous system of the medicinal leech, Hirudo medicinalis, were studied by histological, histochemical and immunocytochemical techniques. The NPG cells are often surrounded by electron-dense microglial cells. The central cytoplasm of NPG cells shows a significant zonation. The zone around the nucleus contains mitochondria, glycogen and vesicles. The cytoplasm also contains many ribosomes, a few dictyosomes and distinct inclusions up to 2 microns in diameter. A second zone around the perinuclear region is marked by the occurrence of bundles of intermediate filaments that correspond in thickness to glial filaments of vertebrates. We found a positive reaction with polyclonal antibodies against human glial fibrillary acidic protein (GFAP), and the areas of intense fluorescence correspond to the regions where intermediate filaments were found to be abundant. The peripheral zone contains numerous membrane stacks that could not be contrasted by lanthane nitrate or tannic acid. Therefore, the membrane stacks could be part of an extensive smooth endoplasmic reticulum, which is characteristic of cells with active lipid metabolism.

Evidence for two isoforms of carbonic anhydrase II in the leech (Hirudo medicinalis) central nervous system

1. We dissected, homogenized and prepared ganglia and connectives from the central nervous system of medicinal leeches for SDS gel electrophoresis. The isolated proteins were transferred to nitrocellulose and incubated with affinity column-purified antibodies. 2. The immunoblots showed a strong positive reaction of a bovine carbonic anhydrase standard at a molecular weight of 29 kDa, and a distinct double-bond at the same molecular weight in the analyzed material. 3. We demonstrated with rat antibodies that carbonic anhydrase II is detectable in the leech central nervous system as the main isoenzyme. 4. The biochemical knowledge of carbonic anhydrase reported here agrees well with the immunocytochemical locations, thus affirming the validity of specific staining.

Arthroscopic staple capsulorrhaphy: a long-term follow-up

Fifty-four shoulders with recurrent anterior shoulder instability were evaluated following arthroscopic staple capsulorrhaphy. Average follow-up for those with only the index surgery was 39 months. Eighteen patients (33%) experienced at least one episode of postoperative instability. Ten underwent an open reconstructive procedure. Routine radiographs at time of follow-up demonstrated loose staples in 15% of asymptomatic patients. Range of motion was preserved following surgery. There was no loss of forward elevation. An average of 5 degrees of external rotation and one spinal segment in internal rotation were lost following surgery. Forty-three percent of overhead athletes were able to return to their preinjury level of activity. Caution should be taken when considering arthroscopic staple capsulorrhaphy as recurrence rates are higher than those following open reconstruction. However, range of motion and functional level are well-maintained. When capsulorrhaphy is performed, consideration should be given to routine staple removal following adequate capsular healing.

Localization of carbonic anhydrase in identified glial cells of the leech central nervous system: application of histochemical and immunocytochemical methods

We localized the enzyme carbonic anhydrase (CA) in frozen sections of the leech (Hirudo medicinalis) central nervous system by two histochemical techniques and the indirect immunofluorescence technique. Hansson's cobalt precipitation method and the use of 1-dimethylamino-naphthalene-5-sulfonamide (DNSA) to build a fluorescent enzyme-substrate complex showed that glial cells are the sites of CA activity in the leech. Neuropil and connective glial cells surrounding the axons had strong CA activity, whereas packet glial cells, which surround neuron cell bodies, and neurons themselves remained unstained. Glial cells reacted markedly with FITC-coupled antibodies against CA isoenzyme II, but experiments with antibodies against CA isoenzyme I showed no reaction.

Effect of pretransplant blood transfusions and splenectomy on renal allograft survival in the Lewis rat

Both pretransplant blood transfusions and pretransplant splenectomy have been shown to improve renal allograft survival in humans and experimental animals. A study was undertaken using the Lewis rat to determine if any combination of pretransplant splenectomy and pretransplant blood transfusions exerted either a synergistic or deleterious effect on renal allograft survival. Pretransplant splenectomy and pretransplant blood transfusions used singly significantly prolonged renal allograft survival. Pretransplant splenectomy followed by 3 blood transfusions also significantly prolonged renal allograft survival. This finding implies that secondary sites of suppressor cell activity, for instance lymph nodes, can be stimulated by blood transfusion and produce prolonged allograft survival in the absence of the spleen. No combination of pretransplant blood transfusion and splenectomy was synergistic. In fact, the group that had pretransplant transfusions followed by splenectomy had allograft survival no different from the control group.