Prevalence of nits and lice in samples of cut hair from floors of barbershops and beauty parlors in Belo Horizonte, Minas Gerais State, Brazil

A louse survey based on samples of cut hair collected from floors of barbershops and beauty parlors was conducted in Belo Horizonte, Minas Gerais State, Brazil, from October 1984 to April 1985, as an alternative way to determine the prevalence of pediculosis capitis in the population. Of 475 samples examined for nits, nymphs, or adults of Pediculus capitis, 140 were infested (29.5%). A total of 58 lice and 3,553 nits were found in 33,632.9 g of hair collected, giving a ratio of 0.10 nit/g. Almost 29% of the nits were viable and capable of being transmitted after hatching. There was significant difference among the infestation rates by socioeconomic levels, and samples from barbershops with male customers were the most infested. Based upon the number of haircuts in each sample, we estimated that 5 or 6% of the population might be infested by this species.     

Inhibition of glucagon-induced glycogenolysis in isolated rat hepatocytes by the Rp diastereomer of adenosine cyclic 3',5'-phosphorothioate

The ability of the Rp diastereomer of adenosine cyclic 3',5'-phosphorothioate (Rp cAMPS) to inhibit glucagon-induced glycogenolysis was studied in hepatocytes isolated from fed rats. Preincubation of the cells for 20 min with progressively higher concentrations of Rp cAMPS followed by a 1 X 10(-9) M glucagon challenge resulted in a 50% inhibition of glucose production over a 30-min period at 2-3 X 10(-6) M Rp cAMPS. A maximal inhibition of 50-74% was achieved, the actual value depending upon the length of preincubation with Rp cAMPS. The inhibitory effect did not increase when the concentration of Rp cAMPS was increased from 3 X 10(-6) to 3 X 10(-4) M. Addition of 1 X 10(-5) M Rp cAMPS to the cells followed by 10(-11) to 10(-6) M glucagon shifted the glucagon concentration required for half-maximal glucose production measured at 10 min to 6-fold higher glucagon concentrations and the concentration of glucagon required for apparent maximal glucose production measured at 10 min to greater than 10-fold higher glucagon concentrations. The cAMP-dependent protein kinase activation curve was similarly shifted to higher concentrations of glucagon. These data show that Rp cAMPS acts as a cAMP antagonist capable of opposing the glucagon-induced activation of cAMP-dependent protein kinase and the concomitant activation of the glycogenolytic cascade.     

Inhibition of hepatic gluconeogenesis by the Rp-diastereomer of adenosine cyclic 3'',5''-phosphorothioate.

The specific intracellular cyclic AMP-dependent protein kinase antagonist, the Rp-diastereomer of adenosine cyclic 3',5'-phosphorothioate (Rp-cAMPS), inhibited both basal and cyclic AMP-agonist-induced rates of gluconeogenesis in hepatocytes isolated from fasted rats. Incubation of the cells in the presence of pyruvate and lactate and either the Sp-diastereomer of adenosine cyclic 3',5'-phosphorothioate (Sp-cAMPS) or glucagon produced a concentration-dependent increase in the rate of gluconeogenic glucose production which was shifted to higher concentrations of Sp-cAMPS or glucagon in the presence of Rp-cAMPS. Incubation of the cells with Rp-cAMPS in the absence of agonist produced no increase in the rate of glucose production and, in most cases, 100 microM-Rp-cAMPS resulted in 14-20% decrease in the substrate-stimulated rate of glucose production. Sp-cAMPS-induced gluconeogenesis was inhibited half-maximally at 1 microM-Rp-cAMPS and glucagon-induced gluconeogenesis was inhibited half-maximally at 12 microM-Rp-cAMPS. Approx. 10-15% of the inhibition of gluconeogenesis observed in the presence of Rp-cAMPS was due to conversion of glucose 6-phosphate to liver glycogen, consistent with Rp-cAMPS-induced reactivation of glycogen synthase. The remaining 85-90% inhibition of gluconeogenic glucose production resulted from the action of Rp-cAMPS on the cyclic AMP-sensitive enzymes controlling the rate of gluconeogenesis.     

Inhibition of glycogenolysis in isolated rat hepatocytes by the Rp diastereomer of adenosine cyclic 3',5'-phosphorothioate

The diastereomeric forms of adenosine cyclic 3',5'-phosphorothioate, Rp cAMPS and Sp cAMPS, were studied in isolated hepatocytes from fed rats for their ability to interact with the intracellular cAMP-dependent protein kinase and to affect the phosphorylase kinase-phosphorylase glycogenolytic cascade. Incubation of the cells with increasing concentrations of Sp cAMPS produced a concentration-dependent activation of cAMP-dependent protein kinase with a concomitant increase in the glycogenolytic rate. Half-maximal and maximal velocities of glycogenolysis were reached at 8 X 10(-7) and 1 X 10(-5) M Sp cAMPS, respectively. Incubation of the cells with 10(-9) to 10(-4) M Rp cAMPS had no effect on basal glucose production or on cAMP-dependent protein kinase activity. Incubation of the cells simultaneously with 3 X 10(-6) M Sp cAMPS and increasing concentrations of Rp cAMPS produced half-maximal inhibition of glycogenolysis at 1 X 10(-5) M Rp cAMPS and maximal inhibition at 1 X 10(-4) M. The concentrations of Sp cAMPS required for half-maximal and maximal activation of glycogenolysis were increased 10-fold when 1 X 10(-5) M Rp cAMPS was present. These data imply that Sp cAMPS is a cAMP-agonist while Rp cAMPS is a cAMP-antagonist.     

Characterization of hemocytes from the marine amphipod Parhyale hawaiensis (Dana 1853): Setting the basis for immunotoxicological studies

Hemocytes are circulating blood cells that play a crucial function in amphipods and other crustacean immune systems. The hemocytes of the marine tropical amphipod Parhyale hawaiensis have been used for the evaluation of DNA damage and micronuclei, but they have not been characterized in the scientific literature. The aim of this study was to describe the hemolymph cells of P. hawaiensis and study their phagocytotic activity. Basic dyes were used to differentiate the cell types and the presence of lipids. The total hemocyte counts (THCs) and the proportion and sizes of the hemocyte types were determined. Hemolymph was exposed to Escherichia coli for verification of the presence of phagocytosis. Three cell types, all containing lipids, were identified in P. hawaiensis: granulocytes (oval shape, 13.4 × 7.6 μm), semi-granulocytes (oval shape, 14.1 × 7.2 μm), and hyalinocytes (round shape, 9.6 × 7.2 μm). Those three cell types were found in different percentages in males (64.8%, 31.1%, and 4.2%) and females (70.1%, 28.2%, and 1.7%). THCs for males were 9007 ± 3800 cells per individual and 4695 ± 1892 cells per individual for females. The cells of E. coli were phagocytized by the hemocytes. Our findings increased the knowledge of hemocytes in P. hawaiensis and is a step forward in using hemocyte-based immune responses as an endpoint in ecotoxicology.     

Isolation and characterization of plasma membrane-associated cortical granules from sea urchin eggs

Cortical granules, which are specialized secretory organelles found in ova of many organisms, have been isolated from the eggs of the sea urchins Arbacia punctulata and Strongylocentrtus pupuratus by a simple, rapid procedure. Electron micropscope examination of cortical granules prepared by this procedure reveals that they are tightly attached to large segments of the plasma membrane and its associated vitelline layer. Further evidence that he cortical granules were associated with these cell surface layers was obtained by (125)I-labeling techniques. The cortical granule preparations were found to be rich in proteoesterase, which was purified 32-fold over that detected in a crude homogenate. Similarly, the specific radioactivity of a (125)I-labeled, surface glycoprotein was increased 40-fold. These facts, coupled with electron microscope observations, indicate the isolation procedure yields a preparation in which both the cortical granules and the plasma membrane-vitelline layer are purified to the same extent. Gel electrophoresis of the membrane-associated cortical granule preparation reveals the presence of at least eight polypeptides. The major polypeptide, which is a glycotprotein of apparent mol wt of 100,000, contains most of the radioactivity introduced by (125)I-labeling of the intact eggs. Lysis of the cortical granules is observed under hypotonic conditions, or under isotonic conditions if Ca(2+) ion is present. When lysis is under isotonic conditions is induced by addition of Ca(2+) ion, the electron-dense contents of the granules remain insoluble. In contrast, hypotonic lysis results in release of the contents of the granule in a soluble form. However, in both cases the (125)I-labeled glycoprotein remains insoluble, presumably because it is a component of either the plasma membrane or the vitelline layer. All these findings indicate that, using this purified preparation, it should be possible to carry out in vitro studies to better define some of the initial, surface-related events observed in vivo upon fertilization.     

Primary structure of the S-peptide formed by digestion of rabbit liver fructose 1,6-biphosphatase with subtilisin.

Digestion of rabbit liver fructose 1,6-bisphosphatase with subtilisin followed by denaturation of the protein yields a peptide containing 60 amino acid residues, including the blocked NH₂-terminus. This peptide has the following sequence: Ac-Ala-Asp-Lys-Ala-Pr o-Phe-Asp-Thr-Asp-Ile-Ser-Thr-Met-Thr-Arg-Phe-Val-Met-Glu-Glu-Gly-Arg-Ly s-Ala-Gly-Gly-Thr-Gly-Glu-Met-Thr-Gln-Leu-Leu-Asn-Ser-Leu-Cys-Thr-Ala-Va l-Lys-Ala-Ile-Ser-Thr-Ala-Val-Arg-Lys-Ala-Gly-Ile-Ala-His-Leu-Tyr-Gly-Ile-Ala.     

Discrete charge calculations of potentiometric titrations for globular proteins: sperm whale myoglobin, hemoglobin alpha chain, cytochrome c.

The modified Tanford-Kirkwood theory of Shire et al. for intramolecular electrostatic interactions has been applied to hydrogen ion equilibria of sperm whale ferrimyoglobin, human hemoglobin α-chain and horse cytochrome c. The model employs two sets of parameters derived from the crystalline protein structures, first, the atomic coordinates of charged amino acid residues and, second, static accessibility factors to reflect their solvent exposure. In addition, a consistent set of intrinsic pK values (pK_int) for the individual groups is employed. The theoretical pK values at half-titration for individual groups in each protein correspond to the available observed pK values, and the theoretical titration curves compare closely with experimental potentiometric curves.     

Structure and Optical Bandgap Relationship of π-Conjugated Systems

In bulk heterojunction photovoltaic systems both the open-circuit voltage as well as the short-circuit current, and hence the power conversion efficiency, are dependent on the optical bandgap of the electron-donor material. While first-principles methods are computationally intensive, simpler model Hamiltonian approaches typically suffer from one or more flaws: inability to optimize the geometries for their own input; absence of general, transferable parameters; and poor performance for non-planar systems. We introduce a set of new and revised parameters for the adapted Su-Schrieffer-Heeger (aSSH) Hamiltonian, which is capable of optimizing geometries, along with rules for applying them to any -conjugated system containing C, N, O, or S, including non-planar systems. The predicted optical bandgaps show excellent agreement to UV-vis spectroscopy data points from literature, with a coefficient of determination , a mean error of −0.05 eV, and a mean absolute deviation of 0.16 eV. We use the model to gain insights from PEDOT, fused thiophene polymers, poly-isothianaphthene, copolymers, and pentacene as sources of design rules in the search for low bandgap materials. Using the model as an in-silico design tool, a copolymer of benzodithiophenes along with a small-molecule derivative of pentacene are proposed as optimal donor materials for organic photovoltaics.