A microdialysis-based analytical system for dynamic monitoring of arsenic transformation under microbial activity.

In this study, a microdialysis (MD) technique was combined with high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for continuous monitoring of the dynamic variations of arsenic species in a microbe-inoculated culture broth. After optimizing the analytical system, retrodialysis was applied to assess the probe recovery and analytical performance of the proposed method. The mean probe recoveries of four arsenic species were in the range from 57.0 to 81.8%. The limit of detection (LOD) for arsenic was in the range of 0.6-1.8 ng mL-1 and 0.032 µM for MDA, respectively. The accuracy was assessed by an addition/recovery test with a satisfactory value of 98.07-109.08% for arsenic species and 93.57-108.15% for MDA, respectively. To evaluate the practical applicability of this method, we monitored, continuously for 72 h, the dynamic variations of the concentrations of the four arsenic species in a standardized bacterial sample (ATCC 25922). After adding the arsenic species into the bacteria-inoculated broth, we found that the concentration of As3+ decreased over time, whereas As5+ increased in concentration. In addition, malondialdehyde (MDA) was also monitored to evaluate the effect of oxidative damage of the arsenic species on the studied microbial system. Our analyses revealed that the dynamic variations of the arsenic species and MDA could be observed continuously during the microbial growth period. This economical and eco-friendly method might also be helpful for monitoring the transformations of other metal species, oxidation processes, and the bioremediation ability of microbial systems.

Unexpected upper airway obstruction due to disseminated human papilloma virus infection involving the pharynx in a parturient.

Human papilloma virus has been implicated as the cause of juvenile-onset recurrent respiratory papillomatosis in first-born children. Thus, cesarean section is strongly recommended by obstetricians to avoid direct contact with papilloma in an infected birth canal. We report a parturient with silent hypopharyngeal papilloma, which was associated with severe clinical problems at the induction of general anesthesia. The anesthesiologist considered general anesthesia for this case because of disseminated skin warts and secondary pus across the patient's body. Although the patient's breathing was smooth before starting general anesthesia, it was difficult to maintain positive pressure ventilation despite administration of a muscle relaxant. High air-way resistance without chest wall motion was noted, despite the insertion of an oral airway. Therefore, direct laryngoscopy was immediately performed and an obstructing mass was found. This mass acted as a check valve during positive ventilation. Our report should remind clinicians that human papilloma virus infection, although benign, can be disastrous in certain circumstances, as in our case where it resulted in airway obstruction and distal spread during cesarean section. Its presence necessitated preoperative laryngoscopic evaluation and aggressive treatment.

Electrophysiological study on the effects of leptin in rat dorsal motor nucleus of the vagus.

Immunoreactivity of leptin receptor (Ob-R) has been detected in rat dorsal motor nucleus of the vagus (DMNV). Here, we confirmed the presence of Ob-R immunoreactivity on retrograde-labeled parasympathetic preganglionic neurons in the DMNV of neonatal rats. The present study investigated the effects of leptin on DMNV neurons, including parasympathetic preganglionic neurons, by using whole cell patch-clamp recording technique in brain stem slices of neonatal rats. Leptin (30-300 nM) induced membrane depolarization and hyperpolarization, respectively, in 14 and 15 out of 80 DMNV neurons tested. Both leptin-induced inward and outward currents persisted in the presence of TTX, indicating that leptin affected DNMV neurons postsynaptically. The current-voltage (I-V) curve of leptin-induced inward currents is characterized by negative slope conductance and has an average reversal potential of -90 +/- 3 mV. The reversal potential of the leptin-induced inward current was shifted to a more positive potential level in a high-potassium medium. These results indicate that a decrease in potassium conductance is likely the main ionic mechanism underlying the leptin-induced depolarization. On the other hand, the I-V curve of leptin-induced outward currents is characterized by positive slope conductance and has an average reversal potential of -88 +/- 3 mV, suggesting that an increase in potassium conductance may underlie leptin-induced hyperpolarization. Most of the leptin-responsive DMNV neurons were identified as being parasympathetic preganglionic neurons. These results suggest that the DMNV is one of the central target sites of leptin, and leptin can regulate parasympathetic outflow from the DMNV by directly acting on the parasympathetic preganglionic neurons of the DMNV.

Labetalol pretreatment reduces blood pressure instability during surgical resection of pheochromocytoma.

BACKGROUND: To evaluate the effect of pretreatment with the mixed alpha- and beta-adrenergic blocker, labetalol, on blood pressure instability during surgical resection of pheochromocytoma. METHODS: Blood pressure stability and surgical results were compared between patients in the saline (n = 11) and labetalol (n = 15) groups. Anesthesia was induced with fentanyl, sodium thiopental and atracurium, and maintained with isoflurane in a 50% oxygen/nitrous oxide mixture. Intravenous labetalol was administered in the labetalol group before surgical incision, with the maximal dose being 1.2 mg/kg, while normal saline was administered to patients in the control, saline, group. Supplemental intravenous sodium nitroprusside (SNP) infusion was administered whenever systolic blood pressure exceeded 180 mmHg. The number of patients with intraoperative hypertension or hypotension, dosage of SNP administered, number of intraoperative hypertension episodes, use of fluid and blood transfusion, and heart rate (defined as the mean of heart rate every 5 minutes throughout the operation) were compared between these two groups. RESULTS: The number of patients with intraoperative hypertension, number of patients receiving SNP, dose of SNP administered, and number of hypertension episodes were significantly lower in patients who received labetalol pretreatment than in control patients. CONCLUSION: This study has demonstrated that labetalol pretreatment (1.2 mg/kg) with supplemental SNP provides more favorable blood pressure control during surgical resection of pheochromocytoma than with SNP alone.

Performing microchannel temperature cycling reactions using reciprocating reagent shuttling along a radial temperature gradient.

This study develops a novel temperature cycling strategy for executing temperature cycling reactions in laser-etched poly(methylmethacrylate) (PMMA) microfluidic chips. The developed microfluidic chip is circular in shape and is clamped in contact with a circular ITO heater chip of an equivalent diameter. Both chips are fabricated using an economic and versatile laser scribing process. Using this arrangement, a self-sustained radial temperature gradient is generated within the microfluidic chip without the need to thermally isolate the different temperature zones. This study demonstrates the temperature cycling capabilities of the reported microfluidic device by a polymerase chain reaction (PCR) process using ribulose 1,5-bisphosphate carboxylase large subunit (rbcL) gene as a template. The temperature ramping rate of the sample inside the microchannel is determined from the spectral change of a thermochromic liquid crystal (TLC) solution pumped into the channel. The present results confirm that a rapid thermal cycling effect is achieved despite the low thermal conductivity of the PMMA substrate. Using IR thermometry, it is found that the radial temperature gradient of the chip is approximately 2 degrees C mm(-1). The simple system presented in this study has considerable potential for miniaturizing complex integrated reactions requiring different cycling parameters.

High frequency jet ventilation in exploration of tracheostomy--a case report.

Exploration of tracheostomy is not uncommon, however, in case a patient with a facial reconstruction flap, trouble may arise because of difficulty in intubation. We hereby report a patient who had a fresh facial reconstruction flap after radical resection of buccal carcinoma, sustained bleeding around the tracheostomy and was scheduled for exploration of tracheostomy. Fiberoptic oral intubation was failed because of profuse secretion and edematous oral mucosa; high frequency jet ventilation (HFJV) was thus applied and made possible with a suction catheter put through the tracheostomy tube. Exploration was performed following withdrawal of the tracheostomy tube. The tracheostomy tube was reinserted under the guidance of the in-place suction tube after uneventful exploration. The probable concomitant complications and contraindications of using HFJV are discussed here. With thorough preparation and careful monitoring, and under the supervision of experienced physicians, transtracheal HFJV can substitute fiberoptic intubation for ventilation in case of exploration of tracheostomy.

Failure to provide adequate one-lung ventilation with a conventional endotracheal tube using a transbronchial approach: a case report.

PURPOSE: To report a case where failure to provide adequate one-lung ventilation during transbronchial intubation resulted in a potentially fatal mishap. CLINICAL FEATURES: A 61-yr-old male was scheduled for right lung lobectomy. Induction of general anesthesia was smooth, and subsequent resection of the right middle lobe was uneventful. Difficult ventilation with high airway pressure and poor right lung re-expansion prompted repositioning of the double-lumen tube after the resection. The removal of the right middle bronchial clamp and associated right mainstem manipulation caused flooding of blood into the double-lumen tube. Mindful of the risk of fatal desaturation, the surgeon immediately opened the right mainstem bronchus and cleared the airway. Confirmation of a displaced double-lumen tube prompted the surgeon to insert an endotracheal tube (internal diameter 5.5 mm) from the opened right mainstem bronchus to the left main bronchus to maintain oxygenation. Although bronchoscopic examination confirmed proper location of the reinserted tube, oxygen saturation was not sufficiently (60%) improved. Another 5.5-mm endotracheal tube was inserted, with its tip inside the right upper bronchiole, for further ventilatory support. Finally, a rise in SpO2 to around 95% allowed completion of surgery. CONCLUSIONS: Displacement of the double-lumen endobronchial tube and flooding with clotted blood will result in potentially fatal ventilation difficulties. Repositioning and cleaning of the tube must be prompt to reduce the risk of hypoxemia. Where emergency single-lung ventilation is required, we suggest the utilization of a modified single-lumen endotracheal tube with a shortened cuff-tip length to ensure an adequate margin of safety for mainstem bronchus intubation.

Anesthetic management of a parturient undergoing cesarean section with a tracheal tumor and hemoptysis.

Anesthetic management of a parturient with respiratory failure associated with hemoptysis, dyspnea, and orthopnea is difficult. An anesthesiologist should realize that the patient's major problem is not solved during the surgery. This circumstance is similar to a patient with associated cardiac disease scheduled for non-cardiac surgery. General anesthesia with endotracheal intubation can provide safe oxygenation for both the parturient and the fetus, but with possible unexpected massive hemoptysis and tumor seeding. Prolonged intubation may delay the patient's pulmonary treatment course. Laryngeal mask anesthesia can provide an airway, but must not be secured due to the risk of aspiration. The need of high doses of inhalation drugs may hinder uterine contractions. The addition of a muscle relaxant will change the patient's respiratory patterns and physiology. Regional anesthesia alone might not be tolerated. A decrease in cough strength, as well as dyspnea, orthopnea, and hyperventilation may be harmful to both the parturient and the fetus. However, we successfully managed this case using epidural anesthesia combined with assisted mask ventilation instead of spontaneous breathing usually provided by a simple mask in almost all American Society of Anesthesiology (ASA) class I-II parturients during cesarean section. The anesthetic level was maintained at T8 with 18 ml of 2% Xylocaine mixed with 2 ml of 7% sodium bicarbonate with 1:200,000 epinephrine epidurally and with the patient in a supine position with the head up at 30 degrees to prevent cephalic spreading and to ensure better pulmonary ventilation.

Red Man's syndrome following administration of vancomycin in a patient under spinal anesthesia--a case report.

Prophylactic antibiotics are frequently administered during anesthesia to reduce the incidence of infection. The most common organisms revealed in wound infections are staphylococci. Vancomycin is the antibiotic of choice for resistant staphylococcal infections and bacterial endocarditis in patient allergic to penicillin. We had a case of tibial osteomyelitis, while undergoing removal of implants under spinal anesthesia developed hypotensions, bradycardia, consciousness change and skin erythematous macular rash after 0.1% vancomycin slow infusion for 10 min. After appropriate management, the patient recovered well and was discharged on the following day. Our report is intended to alert our colleagues that vancomycin can cause hypotension secondary to histamine release, direct myocardial depression and direct peripheral vasodilation. Even cardiac arrest had been reported in the literatures.