Molecular characterization of prophenoloxidase-1 (PPO1) and the inhibitory effect of kojic acid on phenoloxidase (PO) activity and on the development of Zeugodacus tau (Walker) (Diptera: Tephritidae)

Phenoloxidase (PO) plays a key role in melanin biosynthesis during insect development. Here, we isolated the 2310-bp full-length cDNA of PPO1 from Zeugodacus tau, a destructive horticultural pest. qRT-polymerase chain reaction showed that the ZtPPO1 transcripts were highly expressed during larval-prepupal transition and in the haemolymph. When the larvae were fed a 1.66% kojic acid (KA)-containing diet, the levels of the ZtPPO1 transcripts significantly increased by 2.79- and 3.39-fold in the whole larvae and cuticles, respectively, while the corresponding PO activity was significantly reduced; in addition, the larval and pupal durations were significantly prolonged; pupal weights were lowered; and abnormal phenotypes were observed. An in vitro inhibition experiment indicated that KA was an effective competitive inhibitor of PO in Z. tau. Additionally, the functional analysis showed that 20E could significantly up-regulate the expression of ZtPPO1, induce lower pupal weight, and advance pupation. Knockdown of the ZtPPO1 gene by RNAi significantly decreased mRNA levels after 24 h and led to low pupation rates and incomplete pupae with abnormal phenotypes during the larval-pupal interim period. These results proved that PO is important for the normal growth of Z. tau and that KA can disrupt the development of this pest insect.

Overexposure analysis of pulsed distributed feedback laser source

The goal of this study is to assess the risk of overexposure, when DFB dye laser is used for medical treatment in pulsed mode operation. Results of experimental study showing an unexpected rise of energy in pulses of distributed feedback dye laser (DFDL) output due to temperature phase gratings in dye cell during passively Q switched and mode-locked operation is reported. This unintended increase in the number of pulses, pulse duration, per pulse energy may cause side effects, when used for selective photothermolysis. To probe this phenomenon the most commonly used Rh6G dye was excited with 10-20 pulses of second harmonic of a passively Q switched and mode-locked Nd:yttrium-aluminum-garnet(YAG) laser. The outputs of DFDL and Nd:YAG laser were recorded by an Imacon-675 streak camera. The peak of DFDL output pulses was found delayed proportionally from the peak of the Nd:YAG pulses by more than an interpulse period of excitation laser. A computer program was used to simulate the experimentally measured results to estimate the thermal decay constants and energy retained by medium. The delay between peaks of Nd:YAG (input) and DFDL (output) pulses was found to vary from 10 to 14 ns for various cavity lengths. It was interesting to note that for smaller inter-pulse periods the effect of gradual gain buildup satisfied the threshold conditions for some of the pulses that otherwise cannot lase. This may lead to unintended increase in energy fluence causing overexposure-induced bio effects.

A comparative study of positive pressure ventilation via laryngeal mask airway and endotracheal tube

OBJECTIVE

To investigate the use of Laryngeal Mask Airway (LMA) and its comparison with the endotracheal tube for positive pressure ventilation.

SETTING

A tertiary care teaching hospital.

METHODS

Fifty adult ASA I and II patients undergoing peripheral limb surgery were randomly allocated to 2 groups for LMA or endotracheal tube insertion. A standardized anaesthetic technique was used. The groups were then compared regarding haemodynamic changes on insertion as well as removal of LMA and ETT and any complications that occurred were noted.

RESULTS

The haemodynamic response to insertion was significantly attenuated (p < 0.05) in LMA group as compared to ETT group. The cardiovascular response to extubation was not significantly different between the groups. A higher incidence of coughing and mild hypoxaemia at extubation was noted in ETT group as compared to LMA group (p < 0.05) and blood was detected in 4 cases after LMA removal.

CONCLUSION

It is concluded that the use of LMA during positive pressure ventilation is safe in selected cases. There is an attenuated haemodynamic response to insertion of LMA as compared to endotracheal tube which will be beneficial in certain patients e.g., those with ischaemic heart disease, vascular disease and hypertensives.