Productivity, consumers, and the structure of a river food chain

We tested models of food chain dynamics in experimentally manipulated channels within a natural river. As light levels increased, primary productivity and the biomass of algae and primary predators increased, but the biomass of grazers remained relatively constant. In the presence of a fourth trophic level, algae and primary predators decreased, but grazers increased. These results match predictions of food chain models based on classical predator-prey theory and suggest that simple models of multitrophic level interactions are sometimes sufficient to predict the responses of natural communities to changes in environmental productivity and predators.     

Hazards of non coherent light sources as determined by the framework of IEC TR-60825-9

An overview is provided of the scope and application of IEC TR 60825-9 in determination of hazards of non coherent optical radiation sources. Specific areas reviewed in detail include those relating to hazards of ultraviolet radiation, retinal thermal hazard and blue light photochemical hazard. The effect of spectral temperature on relative risk relating to retinal thermal hazard and blue light photochemical hazard are outlined. Assessment of risk factors of these hazards was determined using a range of measurement devices including spectral radiometer, broad band power meter and a locally developed device for determination of pulse profile of pulsed light sources.     

Evaluation of susceptibility testing methods for Burkholderia cepacia complex: a comparison of broth microdilution,agar dilution,gradient strip and EUCAST disc diffusion

ObjectivesTo evaluate the accuracy and reproducibility of antimicrobial susceptibility testing methods in Burkholderia cepacia complex (BCC).MethodsMinocycline, ciprofloxacin, trimethoprim/sulphamethoxazole, meropenem, ceftazidime and chloramphenicol were tested against 155 BCC strains using broth microdilution at 35 ± 1°C (BMD₃₅) in triplicate, then BMD at 30 ± 1°C (BMD₃₀), agar dilution at 30°C and 35°C (AD₃₀ and AD₃₅), gradient strip (GS) and EUCAST standardized disc diffusion (DD) testing methods once.ResultsBMD₃₅ reproducibility ranged from 70% to 84.5% for all agents. Correlations of MICs from BMD₃₅ with BMD₃₀ ranged from 63% to 85%, with AD₃₅ from 32.9% to 87% and with GS methods from 36% to 83.9%. Essential agreement (EA) of MICs by GS with BMD₃₅ ranged from 62.6% (trimethoprim-sulphamethoxazole) to 83.9% (minocycline). EA of EUCAST DD zone diameters using CLSI breakpoint criteria was between 85.8% and 97.4%, however Very Major Errors (VME) for trimethoprim/sulphamethoxazole were 31%.ConclusionsBMD at 35 ± 1°C was poorly reproducible for most agents and no method showed acceptable performance. Of particular concern were the GS results. Although this is the most commonly used method for determining MICs in laboratories, there was poor correlation with BMD₃₅ for meropenem and trimethoprim/sulphamethoxazole. EUCAST DD correlated poorly with BMD₃₅ MICs. This study confirms that no susceptibility method is capable of providing reproducible and accurate MICs when testing BCC.     

Recurrent Spontaneous Paresthesia in the Upper Limb Could Be Due to Migraine: A Case Series

Transient neurologic dysfunction is a characteristic feature of migraine. About 20% of migraineurs may experience various symptoms in the absence of any headache at one time or another. Visual auras are the most common auras of migraine, and migraine is considered as the most common cause of transient vision loss in young patients. Sensory auras are the second most common migrainous auras. However, the literature is silent for isolated sensory aura as a migraine equivalent. Herein we report 14 patients with recurrent episodic paresthesia in the limbs and other body parts. All patients fulfilled the diagnostic criteria of “typical aura without headache” of ICHD‐3β. All patients were subjected to various investigations to rule out secondary causes. Ten patients received antimigraine drugs and all showed a positive response to therapy. Recurrent spontaneous paresthesia is quite common in the general population and many patients remain undiagnosed. We speculate that a subset of patients might be related to migrainous sensory auras.     

Erectile Impotence in Chronic Alcoholics

Erectile impotence is a common complaint in alcoholics, but its mechanism is unknown. We have studied nocturnal penile erection in 13 alcoholics who complained of impotence. Seven had normal erections and their impotence was therefore psychogenic. Six were found to have diminished or absent nocturnal erections. Plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were elevated in this latter group, with the exception of one patient who had only raised FSH. They also had more evidence of neurological damage than the other seven alcoholics, and two had evidence of damage to the parasympathetic nervous system. Investigation of erection during sleep in alcoholic patients with impotence may be useful in differentiating clinically between patients with psychogenic causes and patients with organic causes of impotence.     

Left Main Coronary Atresia in a Child with Absent Pulmonary Valve Syndrome: Early Entrapment of an Innocent Bystander

Atresia of the left main coronary artery is a rare anomaly that, if left untreated, has an unfavorable outcome. We hereby report left main coronary artery atresia in a child with tetralogy of Fallot with absent pulmonary valve and discuss the possible developmental basis of the association.