Middle cerebral air embolism after foam sclerotherapy.

In the recent past, eight cases of transient ischaemic attack or cerebral vascular accident related to foam sclerotherapy have been reported. The following case is reported to add to the world clinical experience and raises the concern that foam sclerotherapy should continue to be evaluated and reported rigorously to establish the incidence of potentially devastating complications. While waiting for clinical studies to further establish best practice in this area of treatment, it may be in our patients' best interests to reserve the option of foaming sclerosants for selected rather than routine cases of venous insufficiency.

Metabolic modeling identifies key constraints on an engineered glycine betaine synthesis pathway in tobacco.

Previous work has shown that tobacco (Nicotiana tabacum) plants engineered to express spinach choline monooxygenase in the chloroplast accumulate very little glycine betaine (GlyBet) unless supplied with choline (Cho). We therefore used metabolic modeling in conjunction with [(14)C]Cho labeling experiments and in vivo (31)P NMR analyses to define the constraints on GlyBet synthesis, and hence the processes likely to require further engineering. The [(14)C]Cho doses used were large enough to markedly perturb Cho and phosphocholine pool sizes, which enabled development and testing of models with rates dynamically responsive to pool sizes, permitting estimation of the kinetic properties of Cho metabolism enzymes and transport systems in vivo. This revealed that import of Cho into the chloroplast is a major constraint on GlyBet synthesis, the import rate being approximately 100-fold lower than the rates of Cho phosphorylation and transport into the vacuole, with which import competes. Simulation studies suggested that, were the chloroplast transport limitation corrected, additional engineering interventions would still be needed to achieve levels of GlyBet as high as those in plants that accumulate GlyBet naturally. This study reveals the rigidity of the Cho metabolism network and illustrates how computer modeling can help guide rational metabolic engineering design.

Gender differences in evaluating social-sexual conduct in the workplace.

Qualitative interviews exploring gender differences in perceptions of sexual harassment were conducted with 100 full-time St. Louis area employees. Women more than men reported that telling dirty/sexual jokes was a non-harassing behavior, qualified behaviors as harassing when they happened in the workplace, and considered behaviors as non-harassing when the man's intentions were not harmful. Men more than women reported that requesting a date was a non-harassing behavior, qualified behaviors as harassing when the woman did not welcome the behavior, and considered behaviors as non-harassing when they did not violate workplace norms. Logistic regression analysis predicted the respondent gender with 86% accuracy. Finally, concept mapping suggested that when women think about harassers they are concerned with power and social aptitude, while men seem to be more concerned about the responsibility and psychological adjustment of perpetrators of sexual harassment. When women think about victims of harassment they are concerned with a woman's assertiveness and work effectiveness, while men are more concerned with the psychological state of the woman and how provocative she is when they think about victims of sexual harassment.

Osmotic stress induces expression of choline monooxygenase in sugar beet and amaranth.

Choline monooxygenase (CMO) catalyzes the committing step in the synthesis of glycine betaine, an osmoprotectant accumulated by many plants in response to salinity and drought. To investigate how these stresses affect CMO expression, a spinach (Spinacia oleracea L., Chenopodiaceae) probe was used to isolate CMO cDNAs from sugar beet (Beta vulgaris L., Chenopodiaceae), a salt- and drought-tolerant crop. The deduced beet CMO amino acid sequence comprised a transit peptide and a 381-residue mature peptide that was 84% identical (97% similar) to that of spinach and that showed the same consensus motif for coordinating a Rieske-type [2Fe-2S] cluster. A mononuclear Fe-binding motif was also present. When water was withheld, leaf relative water content declined to 59% and the levels of CMO mRNA, protein, and enzyme activity rose 3- to 5-fold; rewatering reversed these changes. After gradual salinization (NaCl:CaCl2 = 5.7:1, mol/mol), CMO mRNA, protein, and enzyme levels in leaves increased 3- to 7-fold at 400 mM salt, and returned to uninduced levels when salt was removed. Beet roots also expressed CMO, most strongly when salinized. Salt-inducible CMO mRNA, protein, and enzyme activity were readily detected in leaves of Amaranthus caudatus L. (Amaranthaceae). These data show that CMO most probably has a mononuclear Fe center, is inducibly expressed in roots as well as in leaves of Chenopodiaceae, and is not unique to this family.

The endogenous choline supply limits glycine betaine synthesis in transgenic tobacco expressing choline monooxygenase.

Certain plants produce glycine betaine (GlyBet) in the chloroplast by a two-step oxidation of choline. Introducing GlyBet accumulation into plants that lack it is a well-established target for metabolic engineering because GlyBet can lessen damage from osmotic stress. The first step in GlyBet synthesis is catalyzed by choline mono-oxygenase (CMO), a stromal enzyme with a Rieske-type [2Fe-2S] center. The absence of CMO is the primary constraint on GlyBet production in GlyBet-deficient plants such as tobacco, but the endogenous choline supply is also potentially problematic. To investigate this, we constructed transgenic tobacco plants that constitutively express a spinach CMO cDNA. The CMO protein was correctly compartmented in chloroplasts and was enzymatically active, showing that its [2Fe-2S] cluster had been inserted. Salinization increased CMO protein levels, apparently via a post-transcriptional mechanism, to as high as 10% of that in salinized spinach. However, the GlyBet contents of CMO+ plants were very low (0.02-0.05 mumol g-1 fresh weight) in both unstressed and salinized conditions. Experiments with [14C]GlyBet demonstrated that this was not due to GlyBet catabolism. When CMO+ plants were supplied in culture with 5 mM choline or phosphocholine, their choline and GlyBet levels increased by at least 30-fold. The choline precursors mono- and dimethylethanolamine also enhanced choline and GlyBet levels but ethanolamine did not, pointing to a major constraint on flux to choline at the first methylation step in its synthesis. The extractable activity of the enzyme mediating this step in tobacco was only 3% that of spinach. We conclude that in GlyBet-deficient plants engineered with choline-oxidizing genes, the size of the free choline pool and the metabolic flux to choline need to be increased to attain GlyBet levels as high as those in natural accumulators.

Blood donor rejection rate: HemoCue hemoglobin analyzer vs. microhematocrit.

This study compared 2 different methodologies: hemoglobin by the HemoCue instrument and hematocrit by the microhematocrit method, to determine if there were any significant difference in the values that could affect donor rejection rates. Literature from the 1960s to 1990s reveals a variety of methods for hemoglobin and hematocrit determinations as well as discussions on fingerstick versus earlobe capillary samples. The HemoCue hemoglobin analyzer is a relatively new technology that tests capillary specimens. The copper sulfate method, although the method of choice for measuring prospective donor hemoglobin levels for many years, was not a part of the study. The microhematocrit method has historically been used as the method for measuring hematocrit alone or as a secondary procedure when donors failed the copper sulfate screening test.

Choline monooxygenase, an unusual iron-sulfur enzyme catalyzing the first step of glycine betaine synthesis in plants: prosthetic group characterization and cDNA cloning.

Plants synthesize the osmoprotectant glycine betaine via the route choline --> betaine aldehyde --> glycine betaine. In spinach, the first step is catalyzed by choline monooxygenase (CMO), a ferredoxin-dependent stromal enzyme that has been hypothesized to be an oligomer of identical subunits and to be an Fe-S protein. Analysis by HPLC and matrix-assisted laser desorption ionization MS confirmed that native CMO contains only one type of subunit (Mr 42,864). Determination of acid-labile sulfur and nonheme iron demonstrated that there is one [2Fe-2S] cluster per subunit, and EPR spectral data indicated that this cluster is of the Rieske type--i.e., coordinated by two Cys and two His ligands. A full-length CMO cDNA (1,622 bp) was cloned from spinach using a probe generated by PCR amplification for which the primers were based on internal peptide sequences. The ORF encoded a 440-amino acid polypeptide that included a 60-residue transit peptide. The deduced amino acid sequence included two Cys-His pairs spaced 16 residues apart, a motif characteristic of Rieske-type Fe-S proteins. Larger regions that included this motif also showed some sequence similarity (approximately 40%) to Rieske-type proteins, particularly bacterial oxygenases. Otherwise there was very little similarity between CMO and proteins from plants or other organisms. RNA and immunoblot analyses showed that the expression of CMO in leaves increased several-fold during salinization. We conclude that CMO is a stress-inducible representative of a new class of plant oxygenases.

Carbohydrate metabolism in the mosquito pathogen Bacillus sphaericus 2362.

Bacillus sphaericus 2362 is pathogenic for mosquito larvae and is being considered for large-scale production as a larvicide. The inability of the bacteria to metabolize carbohydrates requires that they be grown on proteinaceous media. This bacterium was found to be unable to transport glucose or sucrose into the cell, and it lacked glucokinase and hexokinase activity. In addition, it lacked phosphoglucose isomerase, phosphofructokinase, and glucose 6-phosphate dehydrogenase, which are early enzymes of the Embden-Myerhof-Parnas and hexose monophosphate pathways. The presence of other enzymes in these pathways was indicated by assay, by the metabolism of glycerol to acetate, and by growth on acetate and gluconate as sole carbon sources. Critical enzymes of the Entner-Doudoroff pathway were also shown to be absent.

Adenylate cyclase, cyclic nucleotide phosphodiesterase, and phosphorylase activity of cardiomyopathic hamster hearts.

Activities of adenylate cyclase in homogenates were reduced, whereas those of phosphodiesterases were elevated in hearts of myopathic hamsters (BIO 82.62). Affinities for either Mg2+ or ATP of cyclase were unaffected in myopathy. Ca2+ stimulation particulate phosphodiesterases was not observed in myopathy. Although the cardiac phosphorylase content was reduced at the advanced stages of myopathy,-AMP/+AMP ratios remained similar to those found in normal hearts.