Examining the Quasi-Static Uniaxial Compressive Behaviour of Commercial High-Performance Epoxy Matrices.

Four commercial high-performance aerospace aromatic epoxy matrices, CYCOM®890, CYCOM®977-2, PR520, and PRISM EP2400, were cured to a standardised 2 h, 180 °C cure cycle and evaluated in quasi-static uniaxial compression, as well as by dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermoplastic toughened CYCOM®977-2 formulation displayed an overall increase in true axial stress values across the entire stress-strain curve relative to the baseline CYCOM®890 sample. The particle-toughened PR520 sample exhibited an overall decrease in true axial stress values past the yield point of the material. The PRISM EP2400 resin, with combined toughening agents, led to true axial stress values across the entire plastic region of the stress-strain curve, which were in line with the stress values observed with the CYCOM®890 material. Interestingly, for all formulations, the dilation angles (associated with the volume change during plastic deformation), recorded at 0.3 plastic strain, were close to 0°, with the variations reflecting the polymer structure. Compression data collected for this series of commercial epoxy resins are in broad agreement with a selection of model epoxy resins based on di- and tetra-functional monomers, cured with polyamines or dicarboxylic anhydrides. However, the fully formulated resins demonstrate a significantly higher compressive modulus than the model resins, albeit at the expense of yield stress.

Variegate porphyria presenting with acute autonomic dysfunction, intussusception and renal infarction.

A 48-year-old man presented with abdominal pain, constipation and irritability one month after starting phenytoin treatment for a generalized seizure. He was hypertensive, tachycardic (BP 174/98, heart rate (HR) 100 bpm supine) and hypovolaemic. Abdominal CT demonstrated transient jejunal intussusception and infarction of the left kidney. Urinary porphobilinogen levels were increased and genetic analysis confirmed the diagnosis of variegate porphyria. Because of ongoing postural hypotension, the patient underwent further autonomic investigations. Levels of blood pressure (MBP), HR and muscle sympathetic activity (MSNA) were increased during the acute attack compared to recovery (131 versus 105 mmHg, 100 versus 60 bpm, 88 versus 26 bursts min(-1)). HR and MSNA did not increase during phase II Valsalva, whereas stroke volume (SV) decays were exaggerated (deltaMBP-56 versus 0-31 mmHg and SV 25% versus 40% baseline). Baroreflex failure causing increased sympathetic activity, decreased sympathetic and parasympathetic rapid responses, loss of splanchnic capacitance and renal salt wasting were the likely mechanisms for postural hypotension. Increased sympathetic activity may also have caused intussusception and focal renal vasoconstriction, both of which may be underdiagnosed causes of abdominal pain in acute porphyria.

Antidepressant-like effects of 5-hydroxytryptamine1A receptor agonists on operant responding under a response duration differentiation schedule.

A response duration differentiation schedule, where rats depress a lever for between 1.0 and 1.3 s to obtain a food reward, provides a useful measure for detecting antidepressant activity. It is known that 5-hydroxytryptamine1A (5-HT1A) receptor agonists exhibit antidepressant-like activity in multiple animal models of depression, however, compounds selective for this receptor have not been tested in this model to date. Thus, the present study sought to determine the effect of the full 5-HT1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and the partial 5-HT1A agonist, buspirone, on responding in the response duration differentiation task. The effects of these drugs were compared to the effects of the non-specific serotonergic agonist, lysergic acid diethylamide (LSD); the phenothiazine, chlorpromazine; the atypical antidepressant, trazodone; and the non-selective 5-HT1A antagonists, propranolol and alprenolol. It was found that propranolol, trazodone, and both the full (8-OH-DPAT) and partial (buspirone) 5-HT1A agonists produced increases in the mean response duration, which is typical of antidepressant activity. By contrast, with the exception of propranolol, compounds lacking antidepressant efficacy (e.g. chlorpromazine, LSD and alprenolol), failed to produce increases in mean response durations. Further, the effects of 8-OH-DPAT were inhibited by pretreatment with the 5-HT1A antagonist, (-)-alprenolol (3.0 and 30.0 mg/kg i.p.). The results of this study provide further support for the suggestion that 5-HT1A agonists may be useful for the treatment of clinical depression and that these effects are specifically mediated by 5-HT1A receptors.

Serendipitous finding of transitional cell carcinoma of the kidney on bone and gallium imaging.

A 50-year-old woman presented with low back pain. Bone scintigraphy showed a focus of increased activity in the upper pole of the left kidney. Subsequent Ga-67 citrate scintigraphy demonstrated this same abnormal focus as a region of increased activity. Ultrasonography showed a renal mass in the upper pole of the left kidney. At surgery a transitional cell carcinoma of the upper pole of the left kidney was found.