Offline glucose biomonitoring in yeast culture by polyamidoamine/cysteamine-modified gold electrodes.

This article deals with the use of pyranose oxidase (PyOx) and glucose oxidase (GOx) enzymes in amperometric biosensor design and their application in monitoring fermentation processes with the combination of flow injection analysis (FIA). The amperometric studies were carried out at -0.7 V by following the oxygen consumption due to the enzymatic reactions for both batch and FIA modes. Optimization studies (enzyme amounts and pH) and analytical parameters such as linearity, repeatability, effect of interference, storage, and operational stabilities have been studied. Under optimized conditions, for the PyOx-based biosensor, linear graph was obtained from 0.025 to 0.5 mM glucose in phosphate buffer (50 mM) at pH 7.0 with the equation of y = 3.358x + 0.028 and R(2) = 0.998. Linearity was found to be 0.01-1.0 mM in citrate buffer (50 mM and pH 4.0) with the equation of y = 1.539x + 0.181 and R(2) = 0.992 for the GOx biosensor. Finally, these biosensor configurations were further evaluated in a conventional flow injection system. Results from batch experiments provide a guide to design sensitive, stable, and interference-free biosensors for FIA mode. Biosensor stability, dynamic range, and repeatability were also studied in FIA conditions, and the applicability for the determination of glucose in fermentation medium could be successfully demonstrated. The FIA-combined glucose biosensor was used for the offline monitoring of yeast fermentation. The obtained results correlated well with HPLC measurements.

In situ synthesis of biomolecule encapsulated gold-cross-linked poly(ethylene glycol) nanocomposite as biosensing platform: a model study.

In situ synthesis of poly(ethylene glycol) (PEG) hydrogels containing gold nanoparticles (AuNPs) and glucose oxidase (GOx) enzyme by photo-induced electron transfer process was reported here and applied in electrochemical glucose biosensing as the model system. Newly designed bionanocomposite matrix by simple one-step fabrication offered a good contact between the active site of the enzyme and AuNPs inside the network that caused the promotion in the electron transfer properties that was evidenced by cyclic voltammetry as well as higher amperometric biosensing responses in comparing with response signals obtained from the matrix without AuNPs. As well as some parameters important in the optimization studies such as optimum pH, enzyme loading and AuNP amount, the analytical characteristics of the biosensor (AuNP/GOx) were examined by the monitoring of chronoamperometric response due to the oxygen consumption through the enzymatic reaction at -0.7 V under optimized conditions at sodium acetate buffer (50 mM, pH 4.0) and the linear graph was obtained in the range of 0.1-1.0 mM glucose. The detection limit (LOD) of the biosensor was calculated as 0.06 mM by using the signal to noise ratio of 3. Moreover, the presence of AuNPs was visualized by TEM. Finally, the biosensor was applied for glucose analysis for some beverages and obtained data were compared with HPLC as the reference method to test the possible matrix effect due to the nature of the samples.

Childhood foreign body aspiration in Istanbul, Turkey.

In this study, we present the data concerning 10 children (six boys, four girls) with a diagnosis of foreign body aspiration (FBA) amongst 19,951 cases that underwent autopsy between the years 1996-2002. Eight of the children were under 2 years old. All the incidents took place at home. One of the parents was in the company of the child at the time of incident. At least one of the risk factors was positive. Interestingly, all of the aspirated material was related to food except one. Only four cases had subpleural petechiae, whereas five of the seven subjects undergoing histopathological evaluation had edema, hyperemia or intra-alveolar fresh bleeding. The legal instructions, which regulate the standards of toy materials, came into force at the end of 2003. Even though the legal instructions regulating the size and consistency of toys are very important to prevent FBA, we believe that the education of the parents and carers in the prevention of food aspiration is of greater importance.

[Juguler vein gunshot injury from blank cartridges]. / Kurusiki tabanca atisi sonucu gelisen juguler ven yaralanmasi.

Blank cartridge guns, which are produced for self-defence needs and considered harmless, can be easily purchased by adults due to lack of legal regulations. We present this case because injuries caused by gunshot from blank cartridges may be fatal and are rarely encountered in emergency departments. A 3-year-old boy was brought to the emergency department since he had a wound on his neck caused accidentally by gunshot from blank cartridges. He had a moderate general condition and pale appearance. There was an irregular-edged, defective wound 2 cm above the sternal notch in midline localization with a dimension of 3 x 4 cm. Computed tomography of the thorax revealed contusion in the apex of the left lung. A 2-mm plastic piece embedded in the left internal jugular vein was removed during the operation. A mass education on danger and harm of these guns as well as legal regulations for restricted use seem to be necessary. Also, physicians should keep in mind that blank cartridge guns can cause fatal injuries.