Borohydride reduction of periodate-oxidized nucleotides; isolation and structure of the reduction intermediate

The reduction of periodate-oxidized nucleotides with sodium borohydride proceeds via a reaction intermediate presumed to be a monoalcohol. The borohydride-reduction intermediate of periodate-oxidized ADP has been isolated by anion-exchange, liquid chromatography, and subjected to further reduction. Using sodium borohydride and sodium borodeuteride alternately in the two reduction steps, it was determined, by ¹H-n.m.r.-spectral analysis, that the two aldehyde groups are sequentially reduced in the order 3′ and 2′, and it was concluded that the isolated intermediate corresponds to the semi-reduced, 3′-alcohol, 2′-aldehyde derivative. This compound should be a useful analog for the study of enzymes and proteins that interact with nucleotides.     

Gene-set analysis and reduction

Gene-set analysis aims to identify differentially expressedgene sets (pathways) by a phenotype in DNA microarray studies.We review here important methodological aspects of gene-setanalysis and illustrate them with varying performance of severalmethods proposed in the literature. We emphasize the importanceof distinguishing between ‘self-contained’ versus‘competitive’ methods, following Goeman and Bühlmann.We also discuss reducing a gene set to its subset, consistingof ‘core members’ that chiefly contribute to thestatistical significance of the differential expression of theinitial gene set by phenotype. Significance analysis of microarrayfor gene-set reduction (SAM-GSR) can be used for an analyticalreduction of gene sets to their core subsets. We apply SAM-GSRon a microarray dataset for identifying biological gene sets(pathways) whose gene expressions are associated with p53 mutationin cancer cell lines. Codes to implement SAM-GSR in the statisticalpackage R can be downloaded from http://www.ualberta.ca/~yyasui/homepage.html.      

Mandibular angle reduction versus mandible reduction

The terms "mandibular angle reduction" and "reduction angleplasty" refer to operations to reduce the width of the lower face and change a square face to an oval one. Because the terms emphasize the word angle, however, they imply that the operations apply to the mandibular angle. The most frequent complaint after these operations is that the change in the lateral appearance is clear but that the change in the frontal appearance is not noticeable. Such a result is related to the fact that bone resection is performed mainly in the mandibular angle area and is focused particularly on resection of the posterior projection through curved ostectomy. That is, because operations limited to the mandibular angle area cannot properly satisfy patients' requirements, the operation must be applied to a larger area. Therefore, it seems reasonable to change the terms "mandibular angle reduction" and "reduction angleplasty" to "mandible reduction" and "reduction mandibuloplasty." In addition, the most important technique in the operation is the resection of the outer cortex of the mandible. In particular, the corticectomy technique using a reciprocating saw is quite safe and effective for the maximum resection of lateral flaring within a very short time.     

Microbial reduction of metals and radionuclides

The microbial reduction of metals has attracted recent interest as these transformations can play crucial roles in the cycling of both inorganic and organic species in a range of environments and, if harnessed, may offer the basis for a wide range of innovative biotechnological processes. Under certain conditions, however, microbial metal reduction can also mobilise toxic metals with potentially calamitous effects on human health. This review focuses on recent research on the reduction of a wide range of metals including Fe(III), Mn(IV) and other more toxic metals such as Cr(VI), Hg(II), Co(III), Pd(II), Au(III), Ag(I), Mo(VI) and V(V). The reduction of metalloids including As(V) and Se(VI) and radionuclides including U(VI), Np(V) and Tc(VII) is also reviewed. Rapid advances over the last decade have resulted in a detailed understanding of some of these transformations at a molecular level. Where known, the mechanisms of metal reduction are discussed, alongside the environmental impact of such transformations and possible biotechnological applications that could utilise these activities.     

不对称还原前手性芳香酮微生物的筛选及反应特性

含芳香基手性醇是许多手性药物合成的关键手性砌块,生物催化不对称还原前手性酮是合成该类醇的重要方法之一.以4'-氯-苯乙酮为模型底物,从土壤中筛选得到一株能高效催化前手性芳香酮不对称还原合成相应手性醇的菌株,鉴定表明该菌株为白地霉( Geotrichum candid ).进一步考察了其催化4'-氯-苯乙酮不对称还原的反应特性,发现还原4'-氯-苯乙酮的产物主要为 S-4'-氯苯乙醇.在合适的反应条件下,其产率达到35%,对映选择性高于97%.     

Dehydroascorbate reduction

Dehydroascorbic acid is generated in plants and animal cells by oxidation of ascorbic acid. The reaction is believed to occur by the one-electron oxidation of ascorbic acid to semidehydroascorbate radical followed by disproportionation to dehydroascorbic acid and ascorbic acid. Semidehydroascorbic acid may recycle to ascorbic acid catalyzed by membrane-bound NADH-semidehydroscorbate reductase. However, disproportionation of the free radical occurs at a rapid rate, 10⁵ M^–1 s^–1, accounting for measurable cellular levels of dehydroascorbate. Dehydroascorbate reductase, studied earlier and more extensively in plants, is now recognized as the intrinsic activity of thioltransferases (glutaredoxins) and protein disulfide isomerase in animal cells. These enzymes catalyze the glutathione-dependent two-electron regeneration of ascorbic acid. The importance of the latter route of ascorbic acid renewal was seen in studies of GSH-deficient rodents (Meister, A. (1992)Biochem. Pharmacol. 44 1905–1915). GSH deficiency in newborn animals resulted in decreased tissue ascorbic acid and increased dehydroascorbate-to-ascorbate ratios. Administration of ascorbic acid daily to GSH-deficient animals decreased animal mortality and cell damage from oxygen stress. A cellular role is proposed for dehydroascorbate in the oxidation of nascent protein dithiols to disulfides catalyzed in the endoplasmic reticulum compartment by protein disulfide isomerase.     

Breast pathology and reduction mammaplasty

Breast cancer is the tumor with the highest prevalence and incidence in women. Reduction mammaplasty is one of the most common procedures performed in Brazil by the plastic surgeon, and it is not uncommon for the surgeon to find a breast tumor during the operation or afterward, when the histopathological report is received. In this study, 2488 patient files were reviewed retrospectively. All patients had undergone reduction mammaplasty at the senior author's private clinic (the Ivo Pitanguy Clinic) between January of 1957 and December of 2002. Resected breast tissue was examined histopathologically. The objective of this study was to verify the occurrence of breast carcinoma found accidentally postoperatively. The senior author's team performed all of the operations and the same pathologist performed every histopathological examination. The histopathological test results were divided into two groups: benign lesions and tumors. The highest frequency of breast pathology was benign lesions, and of them, 80.8 percent involved fibrocystic changes and fibroadiposity. The tumor group was subdivided into benign tumors and malignant tumors. Among the benign tumors, fibroadenoma was the one most common, in 2.2 percent. The frequency of malignant tumors was 0.5 percent of all patients. Most of the histopathological lesions were found in patients between 30 and 50 years of age. A reduced number of patients had no lesions (3.7 percent). Lack of a pathological investigation or a cursory or hurried examination of any mammary tissue by the pathologist may overlook important lesions. In the analysis of these statistics, the concept of normal breast tissue was questioned.     

Breast reduction

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the preoperative considerations that must be weighed to appropriately assess operative risk of breast reduction. 2. Have a full understanding of the basic techniques that are available to treat the patient with macromastia. 3. Identify which patients are best suited to a particular technique. 4. Identify common complications associated with breast reduction and understand how to treat them. SUMMARY: Breast reduction remains a basic plastic surgery procedure designed to alleviate upper torso complaints resulting from macromastia. Historically, the inverted-T inferior pedicle procedure was the dominant technique for the treatment of macromastia for 40 years. The past two decades have seen a reexamination of breast reduction technique in an attempt to improve on the results and minimize complications. As a result, a new genre of procedures based on different pedicles and short-scar skin management techniques has been introduced. With these new procedures, the plastic surgeon now has a variety of different techniques that can be offered for reducing the hypertrophic breast. Strategically applying the concepts inherent in these procedures to the correct patient can provide outstanding results with few complications. In this article, the concepts and results of these various procedures are discussed to give the reader a basic understanding of the options available for breast reduction.     

Against reduction

In Molecular Models: Philosophical Papers on Molecular Biology, Sahotra Sarkar presents a historical and philosophical analysis of four important themes in philosophy of science that have been influenced by discoveries in molecular biology. These are: reduction, function, information and directed mutation. I argue that there is an important difference between the cases of function and information and the more complex case of scientific reduction. In the former cases it makes sense to taxonomise important variations in scientific and philosophical usage of the terms “function” and “information”. However, the variety of usage of “reduction” across scientific disciplines (and across philosophy of science) makes such taxonomy inappropriate. Sarkar presents reduction as a set of facts about the world that science has discovered, but the facts in question are remarkably disparate; variously semantic, epistemic and ontological. I argue that the more natural conclusion of Sarkar’s analysis is eliminativism about reduction as a scientific concept.