A comparison of net and gross rates of oxygen production as a function of light intensity in some natural plankton populations and in a Synechococcus culture

In vitrorates of gross and net oxygen production were measuredas a function of light intensity in some plankton communitiescollected from Bedford Basin, Nova Scotia, and in a monoclonalculture of Synechococcus. The rate of gross oxygen productionwas measured by a technique in which the stable oxygen isotope,¹⁸O, serves as a photosynthetic tracer Net oxygen productionwas measured by automated Winkler technique. The rate of communityrespiration in the light was then determined by the differencebetween gross and net rates of oxygen production. In the naturalpopulations examined, neither gross nor net oxygen productionrates were significantly inhibited at the highest light intensitymeasured (500–800 µE m^–2 s^–1) In a samplein which the dark respiration rate was small relative to themaximal rate of production [P_max;sensu Platt et al (1980) JMar. Res., 38, 687–701] the rates of ‘light’respiration were 3 times greater. In two other communities,with high rates of dark respiration relative to P_maxthe ratesof ‘light’ respiration were closer to rates of darkrespiration. In the Synechococcus clone, both gross and netoxygen production rates were inhibited at high light intensities.Rates of ‘light’ respiration were found to varyas a function of light intensity. The greatest rates of respirationwere measured in samples incubated at light intensities thatwere just saturating (100 µE m^–2 s^–1). Therates of ¹⁴C production were also measured as a function oflight intensity The photosynthetic quotients, based on ¹⁴C productionrates and gross oxygen production rates, average 1 9     

New North American Chrysauginae (Pyralidae) described by E.D. Cashatt

A Ph.D. dissertation completed by E.D. Cashatt in 1968 entitled “Revision of the Chrysauginae of North America” does not meet the criteria of publication so the new taxa described therein are not available per the International Code of Zoological Nomenclature. In order to validate the taxa proposed in that document we formally describe and illustrate the following: Arta brevivalvalis Cashatt, sp. n., Heliades lindae Cashatt, sp. n., Paragalasa Cashatt, gen. n., Paragalasa exospinalis Cashatt, sp. n., and Penthesilea sacculalis baboquivariensis Cashatt, subsp. n. We summarize other taxonomic actions proposed in the dissertation and those proposed by subsequent authors. We provide the current nomenclatural status with the literature citation of the paper in which the current status was proposed. A lectotype is designated for Clydonopteran tecomae. Adult holotypes and associated labels, and genitalia of paratypes are newly illustrated.     

Structural requirements of tropomodulin for tropomyosin binding and actin filament capping

Regulation of actin filament dynamics underlies many cellular functions. Tropomodulin together with tropomyosin can cap the pointed, slowly polymerizing, filament end, inhibiting addition or loss of actin monomers. Tropomodulin has an unstructured N-terminal region that binds tropomyosin and a folded C-terminal domain with six leucine-rich repeats. Of tropomodulin 1's 359 amino acids, an N-terminal fragment (Tmod1(1)(-)(92)) suffices for in vitro function, even though the C-terminal domain can weakly cap filaments independent of tropomyosin. Except for one short alpha-helix with coiled coil propensity (residues 24-35), the Tmod1(1)(-)(92) solution structure shows that the fragment is disordered and highly flexible. On the basis of the solution structure and predicted secondary structure, we have introduced a series of mutations to determine the structural requirements for tropomyosin binding (using native gels and CD) and filament capping (by measuring actin polymerization using pyrene fluorescence). Tmod1(1)(-)(92) fragments with mutations of an interface hydrophobic residue, L27G and L27E, designed to destroy the alpha-helix or coiled coil propensity, lost binding ability to tropomyosin but retained partial capping function in the presence of tropomyosin. Replacement of a flexible region with alpha-helical residues (residues 59-61 mutated to Ala) had no effect on tropomyosin binding but inhibited the capping function. A mutation in a region predicted to be an amphipathic helix (residues 65-75), L71D, destroyed the capping function. The results suggest that molecular flexibility and binding to actin via an amphipathic helix are both required for tropomyosin-dependent capping of the pointed end of the actin filament.     

Comparative analysis of two slc11 (Nramp) loci in Takifugu rubripes

To study the evolution of the solute carrier family 11 (slc11; formerly Nramp) protein, we isolated and characterized two paralogs from the pufferfish Takifugu rubripes (Fugu). These teleost genes, designated Fugu slc11a-a and Fugu slc11a-b, comprise open reading frames of 1743 nucleotides (581 amino acids) and 1662 nt (554 aa), respectively. The proteins are 81% similar, and both exhibit signature features of the slc11 family of proteins including 12 transmembrane domains, a conserved transport motif and a glycosylated loop. Both Fugu paralogs are more Slc11a2-like based on sequence homology and phylogenetic studies. Analysis of gene environment placed both in the proximity of multiple loci syntenic to human chromosome 12q13, that is, within a SLC11A2 gene environment. However, Fugu slc11a-a also gave one match with chromosome 2q35, where human SLC11A1 resides. Functional diversification was suggested by differences in tissue distribution and subcellular localization. Fugu slc11a-a exhibits a restricted expression profile and a complex subcellular localization, including LAMP1 positive late endosomes/lysosomes in transiently transfected mouse macrophages. Fugu slc11a-b is expressed ubiquitously and localizes solely to late endosomes/lysosomes. This comparative analysis extends our understanding of the evolution and function of this important family of divalent cation transporters. [Sequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. AJ496547/8/9 and AJ496550.]     

(4-Piperidinylphenyl)aminoethyl amides as a novel class of non-covalent cathepsin K inhibitors

A series of (4-piperidinylphenyl)aminoethyl amides based on dipeptide anilines were synthesized and tested against cathepsin K, cathepsin L and cathepsin B. These new non-covalent inhibitors exhibited single-digit nM inhibition of the cysteine proteases. Compounds 3 and 7 demonstrated potency in both mouse and human osteoclast resorption assays.     

Craniectomy for malignant cerebral infarction: prevalence and outcomes in US hospitals

Object

Randomized trials have demonstrated the efficacy of craniectomy for the treatment of malignant cerebral edema following ischemic stroke. We sought to determine the prevalence and outcomes related to this by using a national database.

Methods

Patient discharges with ischemic stroke as the primary diagnosis undergoing craniectomy were queried from the US Nationwide Inpatient Sample from 1999 to 2008. A subpopulation of patients was identified that underwent thrombolysis. Two primary end points were examined: in-hospital mortality and discharge to home/routine care. To facilitate interpretations, adjusted prevalence was calculated from the overall prevalence and two age-specific logistic regression models. The predictive margin was then generated using a multivariate logistic regression model to estimate the probability of in-hospital mortality after adjustment for admission type, admission source, length of stay, total hospital charges, chronic comorbidities, and medical complications.

Results

After excluding 71,996 patients with the diagnosis of intracranial hemorrhage and posterior intracranial circulation occlusion, we identified 4,248,955 adult hospitalizations with ischemic stroke as a primary diagnosis. The estimated rates of hospitalizations in craniectomy per 10,000 hospitalizations with ischemic stroke increased from 3.9 in 1999–2000 to 14.46 in 2007–2008 (p for linear trend<0.001). Patients 60+ years of age had in-hospital mortality of 44% while the 18–59 year old group was found to be 24%(p = 0.14). Outcomes were comparable if recombinant tissue plasminogen activator had been administered.

Conclusions

Craniectomy is being increasingly performed for malignant cerebral edema following large territory cerebral ischemia. We suspect that the increase in the annual incidence of DC for malignant cerebral edema is directly related to the expanding collection of evidence in randomized trials that the operation is efficacious when performed in the correct patient population. In hospital mortality is high for all patients undergoing this procedure.