Guanidinium-carboxylate interactions

The crystal structures of the 1:1 complexes methylguanidinium benzylhydrogenmalonate, (C₂N₃H₈)⁺(C₁₀H₉O₄)^?, MGD.BMAL, and methylguanidinium ethylhydrogenmalonate, (C₂N₃H₈)⁺(C₅H₇O₄)^?, MGD.EMAL, and of the 2:1 complex methylguanidinium sulfate, (C₂N₃H₈)₂SO₄, have been determined from three-dimensional X-ray data. For MGD.BMAL, the complex crystallizes in the triclinic space group P with two formula units in a cell of dimensions a = 6.277(5), b = 8.470(3), c = 13.191(6)Å, α= 91.01(1), β= 99.64(9), γ= 90.83(5)°. The structure has been refined to a final value of R = 0.061 based on 1511 intensities. The MGD.EMAL complex is also triclinic, space group P with two molecules in a cell of dimensions a = 9.254(7), b = 9.625(6), c = 6.778(2) Å, α= 109.6(1), β= 100.8(1), γ= 62.7(1)Å. The crystals of this compound are of low quality, and the final value is R = 0.109 based on 706 intensities. (MGD)₂SO₄ is orthorhombic, space group P2₁2₁2₁, with four molecules in a cell of dimensions a = 7.100(4), b = 12.151(3), c = 13.108(2) Å. Refinement has converged to R = 0.054 based on 907 data. All three crystals exhibit extensive interionic hydrogen bonding. The hydrogen bonding in MGD.BMAL includes a Type B interaction and a Type 1 interaction, the latter being a pairwise interaction from both amino nitrogen atoms on the cation to two carboxylate oxygen atoms from the two different carboxylate groups in an anion. In MGD.EMAL, the anion participates in both a Type A and a Type B pairwise interaction with two neighboring cations. The possible implications of the hydrogen bonding patterns in these two compounds for the role of arginyl side chains in protection of γ-carboxyglutamate residues from decarboxylation are discussed.     

Correlations between in Vitro and in Vivo Mechanisms of Pyrethroid Insecticide Action

Correlations between in Vitro and in Vivo Mechanisms of PyrethroidInsecticide Action. GAMMON, D. W. (1985). Fundam. Appl. Toxicol.5, 9–23. Classical neuropharmacological procedures havebeen used to elucidate insecticide mode of action in vitro.A good deal has thus been learned about pyrethroids but noveltechniques have been necessary to explain the toxicology andsymptomology. The free-walking, electrode-implanted cockroachtechnique, which was developed for this purpose, is described.It enabled correlations to be made between symptomology andeffects on specific nerves. The negative temperature coefficientof toxicity of allethrin (the first pyrethroid) was explainedin terms of repetitive firing in peripheral (sensory) nervesrather than by nerve blockage, which had been suggested fromprevious in Vitro studies. The elucidation of target sites invivo and the most useful parameter to study, i.e., repetitivefiring in nerve axons, enabled the definition of a pyrethroidresistance mechanism in a major insect pest. It also showedtwo modes of action for permethrin and cypermethrin, its -cyanoanalog. A structure-activity relationship for a range of pyrethroids,combining in Vitro and in Vivo approaches, confirmed two distincttypes of pyrethroid action. Studies of poisoning signs and nervedisruptions in Vivo in the mouse and cockroach, using diazepamin conjunction with pyrethroids, implicated the GABA-receptorcomplex as a target for -CN-phenoxybenzyl pyrethroids. Thiswas confirmed by making conductance measurements in crayfishclaw opener muscle fibers in Vitro.     

A Randomized‐Controlled Pilot Study Comparing ICD Implantation with and Without Intraoperative Defibrillation Testing in Patients with Heart Failure and Severe Left Ventricular Dysfunction: A Substudy of the RAFT Trial

Comparing ICD Implantation with and Without Intraoperative Defibrillation Testing. Introduction: The need to perform defibrillation testing (DT) at the time of implantable cardioverter defibrillator (ICD) insertion is controversial. In the absence of randomized trials, some regions now perform more than half of ICD implants without DT. Methods: During the last year of enrolment in the Resynchronization for Ambulatory Heart Failure Trial, a substudy randomized patients to ICD implantation with versus without DT. Results: Among 252 patients screened, 145 were enrolled; 75 randomized to DT and 70 to no DT. Patients were similar in terms of age (65.9 ± 9.3 years vs 67.9 ± 8.9 years); LVEF (24.7 ± 4.6% vs 23.6 ± 4.6%), QRS width (154.8 ± 23.5 vs 155.8 ± 23.6 ms), and history of atrial fibrillation (5% vs 6%). All 68 patients in the DT arm tested according to the protocol achieved a successful DT (≤25 J); 96% without requiring any system modification. No patient experienced perioperative stroke, myocardial infarction, heart failure (HF), intubation or unplanned ICU stay. The length of hospital stay was not prolonged in the DT group: 20.2 ± 26.3 hours versus 21.3 ± 23.0 hours, P = 0.79. One patient in the DT arm had a failed appropriate shock and no patient suffered an arrhythmic death. The composite of HF hospitalization or all‐cause mortality occurred in 10% of patients in the no‐DT arm and 19% of patients in the DT arm (HR = 0.53, 95% CI: 0.21–1.31, P = 0.14). Conclusions: In this randomized trial, perioperative complications, failed appropriate shocks, and arrhythmic death were all uncommon regardless of DT. There was a nonsignificant increase in the risk of death or HF hospitalization with DT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1313‐1316, December 2012)     

Body weight, exercise and menstrual status among ballet dancers in training

Summary. A prospective study of the menstrual pattern and weight changes was made in the first year of training of 29 new female entrants to a professional ballet school. Seventy-nine per cent of the student girls had menstrual disturbances at entry: primary amenorrhoea, four; secondary amenorrhoea, 11; irregular menses, eight. The incidence of secondary amenorrhoea increase substantially by the end of the year (20), but was not associated with any significant change in body weight. Only three students menstruated regularly during the year. Menstrual regularity improved during periods of injury and long vacation and it appears that deterioration of the menstrual pattern during dancing periods was related to strenuous physical exercise rather than to any change in body weight.     

Purification and primary structure of ostrich pancreatic polypeptide

Pancreatic polypeptide has been isolated from ostrich pancreas by gel filtration, ion exchange chromatography and high pressure liquid chromatography. The ostrich peptide contains 36 amino acids and has an amino acid composition similar to pancreatic polypeptide of other avian species. The primary structure of ostrich pancreatic polypeptide differs from that of the chicken peptide only at residues 3 and 18 where the ostrich peptide contains an alanine and a valine residue compared to the serine and isoleucine residues found in those positions in the chicken peptide.