The relationship between the pharmacokinetics of intravenous cismethrin and bioresmethrin and their mammalian toxicity

The distribution and excretion of [¹⁴C]alcohol-labeled cismethrin and bioresmethrin was determined after intravenous administration to rats. Initially the label distribution of both isomers was similar, but differences occurred at later times mainly due to the retention of 5-benzyl-3-furylcarboxylic acid, a metabolite of bioresmethrin, in high concentration in the blood. Retention of this metabolite accounted for the slower excretion of bioresmethrin label compared to cismethrin. After administration of either isomer, parent pyrethroid was rapidly cleared from the blood and liver, and both isomers rapidly entered the central nervous system reaching peak concentrations within 2–5 min. Brain cismethrin concentrations exceeding 3.5 nmol/g were associated only with animals showing tremors. These levels of cismethrin are maintained for up to 30 min but bioresmethrin was depleted more rapidly possibly due to brain metabolism. It is concluded that the low toxicity of bioresmethrin is possibly due to the inability of this isomer to interact with the site of action in the central nervous system and not, as previously suggested, primarily because of more rapid metabolism in the liver.     

Structural studies on transfer RNA: preliminary crystallographic analysis

Single-crystal diffraction patterns from Escherichia coli leucine tRNA and yeast formylmethionine tRNA show a tetragonal lattice for the former, with a = 46 angstroms and c = 137 angstroms, and a hexagonal lattice for the latter, with a = 115 angstroms and c = 137 angstroms. Initial analysis suggests a molecule with a long, double helix parallel to the c-axis for both crystals.     

Identification of a blue photoluminescent composite material from a combinatorial library

A quaternary combinatorial masking strategy was used in conjunction with photolithography to generate compositionally diverse thin-film phosphor libraries containing 1024 different compositions on substrates 2.5 centimeters square. A parallel imaging system and scanning spectrophotometer were used to identify and characterize compositions in the library with interesting luminescent behavior. Optimal compositions were identified with the use of gradient libraries, in which the stoichiometry of a material was varied continuously. This process led to the identification of an efficient blue photoluminescent composite material, Gd3Ga5O12/SiO2. Experimental evidence suggests that luminescence in this material may arise from interfacial effects between SiO2 and Gd3Ga5O12.     

Lunar Fe and Ti abundances: comparison of lunar prospector and clementine data

The Lunar Prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of Clementine spectral reflectance data. With the iron and titanium dependence removed, the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium, incompatible rare earth elements that are enriched in the final phases of magma crystallization. These regions are found mainly around the ramparts of the Imbrium impact basin but not around the other basins, including the much larger and deeper South Pole-Aitken basin. This result confirms the compositional uniqueness of the surface and interior of the Imbrium region.     

Report on the 43rd Annual Meeting of the DPG-Working Group Nematology

Journal of Plant Diseases and Protection -     

Soil invertebrates and the degradation of vanillin,cinnamic acid,and lignins

A range of 8–25% of fed cinnamic 2-[¹⁴C] acid and 9–14% of injected vanillin 5-[¹⁴C] were oxidised to ¹⁴CO₂ at 15 C over 7 and 6 days respectively in an isopod, Oiuscus asellus; a millipede, Pseudopolydesmus serratus; a slug, Deroceras reticulatum; a snail, Oxychilus draparnaldi; and an earthworm, Eisenia foetida. Approximately 2–10% of nonmetabolised and 13–48%, of metabolised vanillin were present in the animal tissues after 6 days. Correspondingly. 1–4% and 22–66% of these materials were found in egesta.A millipede (Oxidus gracilis), O. asellus. D. reticuluttum. O. draparnaldi, and E. foetida were found unable to degrade ring [¹⁴C]-, methoxy [¹⁴C]- and side chain [¹⁴C]-lignin to ¹⁴CO₂ over 10 days, thus providing very strong evidence that these invertebrates are incapable of degrading liginin.     

Comparison of Two Doses of the GnRH Antagonist, Acyline, for Pregnancy Termination in Bitches

Gonadotropin-releasing hormone (GnRH) antagonists are particularly useful when a rapid inhibitory effect on the gonadal axis is required. The aim of this study was to test the efficacy and clinical safety of a low and high dose of the third generation GnRH antagonist, acyline, on pregnancy termination in female dogs. The effect of the antagonist on the progesterone (P₄) serum concentration was also described. Twenty-one mid-pregnant bitches were randomly assigned to a single subcutaneous (SC) dose of a placebo (PLACE; n = 7), a low (ACY-L; 110 μg/kg; n = 6) or high (ACY-H; 330 μg/kg; n = 8) dose of acyline. The animals were followed up for 15 days. All ACY treated but no placebo-treated animals terminated their pregnancy by abortion (p < 0.01). The ACY-L and ACY-H groups interrupted their pregnancy 7 ± 1.9 and 6.4 ± 1.3   days after treatment, respectively (p = 0.7). A significant interaction between treatment and day was found (p < 0.01) for P₄ serum concentrations when PLACE was compared with both ACY groups. No difference was found for this hormone between both ACY groups (p > 0.05) where P₄ diminished throughout the study. The decreasing rate varied among animals and was closely related to the time of abortion when P₄ reached basal concentrations. In PLACE animals, gestation progressed normally and P₄ did not change throughout the study (p > 0.05). None of the bitches presented side effects. It was concluded that acyline safely terminated mid-pregnancy by permanently decreasing P₄ serum concentrations.     

Reproductive Performance of Rabbit Does Artificially Inseminated via Intravaginal Administration of [des-Gly 10, d-Ala6]-LHRH Ethylamide as Ovulation Inductor

This study was aimed to evaluate the reproductive performance of rabbit does artificially inseminated (AI) with a GnRH analogue [des‐Gly10, d ‐Ala6]‐LHRH. ethylamide to induce ovulation by intravaginal administration, delivered in the seminal dose. In a preliminary experiment, 39 does were divided into three groups (n = 13) that, at the time of AI, received the following ovulation induction treatments: (i) control group: 20 μg of gonadorelin administered intramuscularly; (ii) 25 μg of the GnRH analogue added to the seminal dose; (iii) 30 μg of the GnRH analogue added to the seminal dose. Fertility did not differ between the three groups (control: 80.6%, group 2: 82.8%, group 3: 73.3%). In a second experiment, a large‐scale field trial was conducted to test the use of 25 μg of the GnRH analogue [des‐Gly10, d ‐Ala6]‐LHRH ethylamide delivered in the seminal dose (n = 270) against 20 μg of gonadorelin administered intramuscularly. Fertility was higher (p < 0.05) when ovulation was induced by intravaginal administration of the GnRH agonist (91.1% vs 85.6%). Prolificacy or mortality at birth was never affected by the ovulation induction treatments. In a third experiment, two groups of does [control group (n = 39): ovulation was induced using 20 μg of gonadorelin administered intramuscularly; treatment group (n = 40): ovulation was induced using 25 μg of [(des‐Gly10, d ‐Ala6)‐LHRH ethylamide added to the seminal dose] were inseminated at 42‐day intervals for five successive AI cycles, to test the response to the GnRH agonist after repeated intravaginal administration to the same animals. Fertility and prolificacy were not influenced by the ovulation induction treatment neither there was an interaction between treatment and parity. The last experiment was aimed to determine whether it could be possible to add the GnRH agonist to the semen in the AI Center, just after semen collection and dilution, or it would have to be added in the farm, immediately before AI. Kindling rates did not significantly differ when ovulation was induced by intramuscular injection of gonadorelin (84.5%) or when the GnRH agonist was added to the seminal dose just at the moment (93.8 %) or 24 h before AI (90.4 %), but it was significantly lower when the hormone was added to the semen 32 h before AI (76.3 %). Prolificacy, however, was not influenced by the ovulation induction treatment.     

Protein elongation rates in tissues of growing and adult sheep

To identify the relative roles of translation initiation and elongation in the long term control of protein synthesis in ovine tissues, fractional synthesis rates (FSR) and ribosomal transit times (RTT) were measured in vivo in 24 ewe lambs at 3 levels of intake [maintenance (M), 1.5M, and 2M] and 8 mature ewes at 2M intake. After 17 to 25 d on treatment, animals were given an i.v. flooding dose of l-[ring-2,6-(3)H]phenylalanine and tissues were collected for analysis of radioactivity in free protein, total protein, and nascent ribosome-associated proteins. Ribosome transit time (the inverse of elongation rate) averaged 83, 393, 183, 241, 85, and 113 s for liver, duodenum, skin, rumen, semimembranosus, and LM, respectively. In response to an increased level of intake, protein FSR increased (P < 0.01) in all tissues except rumen and was attributed to greater translational efficiency. There was no effect (P > 0.50) of intake on RTT in these tissues, and the estimated proportion of ribosomes attached to and actively translating mRNA was increased (P < 0.07), indicating that an upregulation of initiation was responsible for the greater FSR. Mature ewes exhibited lower (P < 0.10) protein FSR in all tissues compared with lambs, which was related to a decline in the RNA:protein ratio in all tissues except for liver and duodenum. In all tissues but liver and semimembranosus, RTT increased (P < 0.10) with age. The lower elongation rate was not considered to have influenced the protein synthetic rate, but it caused an increase in the proportion of ribosomes actively translating mRNA. It is anticipated that this work will provide direction to future studies of the molecular mechanisms of chronic FSR control.