Insulin therapy for inpatients with diabetes: Perceptions of resident physicians from disparate geographic training programs

Background: Improving diabetes management in hospitalized patients will require educational efforts for all practitioners, particularly resident physicians. Thus, a better understanding of residents' beliefs about diabetes in the hospital must be obtained.Objective: The purpose of this article was to compare and contrast perceptions of resident physicians from 2 geographically distinct training programs regarding management of inpatients with diabetes.Methods: Residents from training programs in the southwestern and southeastern United States were surveyed in 2006 and 2007 about their views on the importance of inpatient glucose control, their perceptions about desirable target glucose ranges, and the problems they encountered when trying to manage hyperglycemia in hospitalized patients.Results: Responses were obtained from 52 of 66 residents at site 1 and from 65 of 85 residents at site 2 (N = 117 total respondents; total response, 77%; mean age, 31 years; 48% men; 61% primary care). Combined analyses revealed that respondents believed that glucose control was “very important” in critically ill patients (96%), perioperative patients (82%), and noncritically ill patients (66%). Most residents indicated that they would target a therapeutic glucose range within published recommendations. Less than half felt “very comfortable” managing inpatient hyperglycemia, hypoglycemia, subcutaneous insulin, or insulin drips. Respondents were not very familiar with existing institutional policies or preprinted order sets for insulin therapy. The most commonly reported barrier to management of inpatient hyper-glycemia was lack of knowledge about appropriate insulin regimens and their use.Conclusions: Trainees from 2 very different educational programs shared common beliefs, knowledge deficits, and perceived barriers about inpatient glucose management. Our findings indicate that trainees were uncertain about how to use insulin therapy in the hospital. Future inpatient diabetes quality-improvement efforts should focus on development of uniform educational programs targeting the management of inpatient diabetes, particularly as it relates to insulin use.     

Detailed analysis of the microdiversity of Prochlorococcus populations along a North-South Atlantic Ocean transect

In order to understand how environmental factors shape the diversity of Prochlorococcus in the Atlantic Ocean, we have elucidated the microdiversity along a north–south transect. The polymerase chain reaction-restriction fragment length polymorphism analysis of the genetic diversity of rpoC1 gene fragments of Prochlorococcus at 12 sampling sites revealed a latitudinal pattern in Prochlorococcus RFLP-type diversity in the samples collected from two depths. At the depth to which 14% of surface irradiance penetrated, HLII clones dominated the stations closest to the equator. The percentage of HLI clones increased with distance from the equator and LL clones were found only at the most northern and southern stations. In contrast, deeper (1% light depth) water samples did not show any overall trend in Prochlorococcus diversity or clade dominance. Multivariate statistical analyses indicated that Prochlorococcus diversity was linked to water temperature (partially an effect of latitude) and depth (which was linked to light penetration and turbidity). Phylogenetic analysis of the sequences obtained from the 423 different environmental RFLP-types detected in this study indicated that the HLII and HLI populations were composed of a wide range of genetically different clones, while the LL Prochlorococcus clade was less diverse, although half of the samples screened in this study derived from the 1% light depth.     

Aromatase-independent testosterone conversion into estrogenic steroids is inhibited by a 5 alpha-reductase inhibitor

Estrogens are generated mainly by the action of aromatase, which converts testosterone to estradiol and androstenedione to estrone. However, in addition to estradiol and estrone, a variety of other steroids, whose synthesis is not dependent on aromatase, can stimulate the estrogen receptor. Here we show that testosterone is converted into such estrogenic steroids by aromatase-negative HeLa cells. This aromatase-independent generation of estrogenic steroids is seen in aromatase-positive MCF-7 cells as well. In both cell lines, the synthesis of estrogenic steroids was blocked by inhibition of testosterone conversion into dihydrotestosterone using a 5 alpha-reductase inhibitor finasteride, suggesting that they are generated downstream of dihydrotestosterone. This finding raises the possibility that the combination of a 5 alpha-reductase inhibitor and an aromatase inhibitor may reduce estrogenic steroids in vivo more completely than an aromatase inhibitor alone.     

The Relationship Between the Rate of Molecular Evolution and the Rate of Genome Rearrangement in Animal Mitochondrial Genomes

Evolution of mitochondrial genes is far from clock-like. The substitution rate varies considerably between species, and there are many species that have a significantly increased rate with respect to their close relatives. There is also considerable variation among species in the rate of gene order rearrangement. Using a set of 55 complete arthropod mitochondrial genomes, we estimate the evolutionary distance from the common ancestor to each species using protein sequences, tRNA sequences, and breakpoint distances (a measure of the degree of genome rearrangement). All these distance measures are correlated. We use relative rate tests to compare pairs of related species in several animal phyla. In the majority of cases, the species with the more highly rearranged genome also has a significantly higher rate of sequence evolution. Species with higher amino acid substitution rates in mitochondria also have more variable amino acid composition in response to mutation pressure. We discuss the possible causes of variation in rates of sequence evolution and gene rearrangement among species and the possible reasons for the observed correlation between the two rates. [Reviewing Editor: Dr. David Pollock]     

Targeting the role of a key conserved motif for substrate selection and catalysis by 3-deoxy-D-manno-octulosonate 8-phosphate synthase

3-Deoxy-D-manno-octulosonate 8-phosphate synthase (KDO8PS) catalyzes the reaction between three-carbon phosphoenolpyruvate (PEP) and five-carbon d-arabinose 5-phosphate (A5P), generating KDO8P, a key intermediate in the biosynthetic pathway to 3-deoxy-D-manno-octulosonate, a component of the lipopolysaccharide of the Gram-negative bacterial cell wall. Both metal-dependent and metal-independent forms of KDO8PS have been characterized. KDO8PS is evolutionarily and mechanistically related to the first enzyme of the shikimate pathway, the obligately divalent metal ion-dependent 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAH7PS) that couples PEP and four-carbon D-erythrose 4-phosphate (E4P) to give DAH7P. In KDO8PS, an absolutely conserved KANRS motif forms part of the A5P binding site, whereas in DAH7PS, an absolutely conserved KPR(S/T) motif accommodates E4P. Here, we have characterized four mutants of this motif (AANRS, KAARS, KARS, and KPRS) in metal-dependent KDO8PS from Acidithiobacillus ferrooxidans and metal-independent KDO8PS from Neisseria meningitidis to test the roles of the universal Lys and the Ala-Asn portion of the KANRS motif. The X-ray structures, determined for the N. meningitidis KDO8PS mutants, indicated no gross structural penalty resulting from mutation, but the subtle changes observed in the active sites of these mutant proteins correlated with their altered catalytic function. (1) The AANRS mutations destroyed catalytic activity. (2) The KAARS mutations lowered substrate selectivity, as well as activity. (3) Replacing KANRS with KARS or KPRS destroyed KDO8PS activity but did not produce a functional DAH7PS. Thus, Lys is critical to catalysis, and other changes are necessary to switch substrate specificity for both the metal-independent and metal-dependent forms of these enzymes.     

Oligomerization state of dynamin 2 in cell membranes using TIRF and number and brightness analysis

Dynamin 2 is an ubiquitously expressed ∼100 kDa GTPase involved in receptor-mediated endocytosis, Golgi budding, and cytoskeletal reorganization. Dynamin molecules assemble around the necks of budding vesicles and constrict membranes in a GTP-dependent process, resulting in vesicle release. The oligomerization state of dynamin 2 in the membrane is still controversial. We investigated dynamin 2 within the plasma membrane of live cells using total internal reflection microscopy coupled with number and brightness analysis. Our results demonstrate that dynamin 2 is primarily tetrameric throughout the entire cell membrane, aside from punctate structures that may correspond to regions of membrane vesiculation.     

Genomic data reject the hypothesis of a prosimian primate clade

The phylogenetic position of tarsiers within the primates has been a controversial subject for over a century. Despite numerous morphological and molecular studies, there has been weak support for grouping tarsiers with either strepsirrhine primates in a prosimian clade or with anthropoids in a haplorrhine clade. Here, we take advantage of the recently released whole genome assembly of the Philippine tarsier, Tarsius syrichta, in order to infer the phylogenetic relationship of Tarsius within the order Primates. We also present estimates of divergence times within the primates. Using a 1.26 million base pair multiple sequence alignment derived from 1078 orthologous genes, we provide overwhelming statistical support for the presence of a haplorrhine clade. We also present divergence date estimates using local relaxed molecular clock methods. The estimated time of the most recent common ancestor of extant Primates ranged from 64.9 Ma to 72.6 Ma, and haplorrhines were estimated to have a most recent common ancestor between 58.9 Ma and 68.6 Ma. Examination of rates of nucleotide substitution in the three major extant primate clades show that anthropoids have a slower substitution rate than either strepsirrhines or tarsiers. Our results provide the framework on which primate morphological, reproductive, and genomic features can be reconstructed in the broader context of mammalian phylogeny.     

Quantification of protein-protein interactions using fluorescence polarization.

Quantitative determinations of the dissociation constants of biomolecular interactions, in particular protein-protein interactions, are essential for a detailed understanding of the molecular basis of their specificities. Fluorescence spectroscopy is particularly well suited for such studies. This article highlights the theoretical and practical aspects of fluorescence polarization and its application to the study of protein-protein interactions. Consideration is given to the nature of the different types of fluorescence probes available and the probe characteristics appropriate for the system under investigation. Several examples from the literature are discussed that illustrate different practical aspects of the technique applied to diverse systems.     

Influence of White Clover Mosaic Potexvirus Infection on the Endogenous Cytokinin Content of Bean

The cytokinin content in the primary leaves of bean (Phaseolus vulgaris) was monitored for 10 d after inoculation with white clover mosaic potexvirus. The cytokinins were isolated, purified, separated by high-performance liquid chromatography, and quantified by radioimmunoassay. The cytokinins detected at the time of inoculation (d 0) were: (a) the free bases, zeatin (Z), dihydrozeatin (DZ), and isopentenyladenine; (b) the riboside, DZ riboside (DZR); (c) the O-glucosides of DZ, DZR, and Z riboside; (d) the nucleotides, Z riboside-5′-monophosphate and isopentenyladenosine-5′-monophosphate; and (e) trace amounts of Z-9-glucoside and DZ-9-glucoside. During the 10 d after inoculation with white clover mosaic potexvirus, marked quantitative changes in this cytokinin profile were observed. The concentration of the free bases and DZR decreased, accompanied by an increase in the 9-glucosides and the nucleotides. Virus titer increased rapidly 3 d after inoculation, attaining a maximum level at d 5. This increase coincided with the increases in the 9-glucosides and the nucleotides. We propose that the decline in the cytokinin free bases and riboside may allow the increase of virus titer in bean and lead to the senescence of infected leaves.