Synthesis and characterization of InNbO4 nanopowder for gas sensors.

Indium niobate (InNbO(4)) nanopowder was prepared by a comparatively low temperature niobium citrate complex process. The prepared InNbO(4) was characterized by thermal analysis, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy, diffuse reflectance spectroscopy (DRS), and impedance studies. It revealed that the well crystalline monoclinic InNbO(4) nanopowder was obtained at the calcination temperature of 600°C. The average particle diameter was 22nm. The optical band gap was found to be 2.66eV. The temperature dependent conductivity obeyed Arrhenius relation. The activation energy of the conductivity process was calculated to be 0.43eV. The gas sensing behaviour of the prepared InNbO(4) was studied by measuring the change in resistance of the sensor material as a function of various concentrations of the test gases such as liquid petroleum gas (LPG), ammonia (NH(3)) and ethanol (C(2)H(5)OH) at their optimized operating temperature. InNbO(4) had a better sensitivity to LPG (0.97) and NH(3) (0.70) gas than ethanol (0.46). The sensor responses of InNbO(4) as a function of gas concentrations and with recovery time were also studied in detail.

Isolation and characterization of a process impurity in tizanidine hydrochloride.

A new process impurity was detected during the HPLC analysis of Tizanidine hydrochloride (I) batches. The impurity (II) was isolated by preparative HPLC and characterized by NMR and Mass spectral analysis as 5-S-ethyl-N-(4,5-dihydro-1H-imidazol-2-yl)-2,1,3-benzothiadiazol-4-amine hydrochloride.

A new stability indicating HPLC method for related substances in zolmitriptan.

A sensitive, precise, specific, linear and stability indicating isocratic HPLC method was developed for the analysis of related substances in zolmitriptan. The potential known related substances are (S)-4-(4-aminobenzyl)-1,3-oxazolidin-2-one (impurity I) and (S)-4-(4-hydrazinobenzyl)-1,3-oxazolidin-2-one (impurity II). The method can be used for the detection and quantification of known and unknown impurities and degradants in the drug substance zolmitriptan during routine analysis and also for stability studies in view of its capability to separate degradation products.

HPLC method for simultaneous determination of impurities and degradation products in zonisamide.

A gradient reversed phase HPLC method was developed and validated for the analysis of related substances in zonisamide (1,2-benzisoxazole-3-methanesulfonamide), using a Waters Symmetry C8 (150*3.9 mm) column with a flow rate of 1.0 ml/min and detection at 280 nm. The mobile phase component A consisted of a mixture of 0.02 M aqueous potassium dihydrogen phosphate-acetonitrile-methanol (75:10:15 v/v/v), pH adjusted to 4.0 with orthophosphoric acid. The mobile phase component B consisted of a mixture of 0.02 M aqueous potassium dihydrogen phosphate-acetonitrile-methanol (15:40:45 v/v/v), pH 2.0 with orthophosphoric acid. The limit of detection and limit of quantitation were in the range of 0.001-0.007% and 0.0035-0.25% respectively with respect to sample concentration of 2 mg/ml. The method was linear in the range of LOQ level to 200% of specified limits for II-VIII (< 0.10%, r(2)= 0.9958-0.9999). The method is sensitive, specific, linear, accurate, precise and stability-indicating for the detection and quantitation of precursors (viz., 4-hydroxycoumarin, 1,2-benzisoxazole-3-acetic acid, 1,2-benzisoxazole-3-bromoacetic acid, 1,2-benzisoxazole-3-methylbromide, sodium 1,2-benzisoxazole-3-methanesulfonate), process impurities (viz., 2-hydroxyacetophenone oxime and 3,3,3-tribromomethyl-1,2-benzisoxazole) and drug degradation products formed under stress conditions.

Kodaistatins, novel inhibitors of glucose-6-phosphate translocase T1 from Aspergillus terreus thom DSM 11247. Isolation and structural elucidation.

Two novel compounds, kodaistatin A, C35H34O11, molecular weight 630, and kodaistatin C, C35H34O12, molecular weight 646, have been isolated from cultures of Aspergillus terreus Thom DSM 11247 by solid-phase extraction, size-exclusion chromatography, and various preparative HPLC steps. The use of a range of 2D NMR measurements, in particular 13C-13C correlation measurements, has led to the clarification of the structure of kodaistatin A. Kodaistatin C is a hydroxylated derivative of kodaistatin A. Both natural products contain hydroxylated aspulvinones and identical highly substituted polyketide units. An X-ray single crystal structure analysis of aspulvinon E demonstrated the z-configuration at the central double bond. The kodaistatins are effective inhibitors of the glucose-6-phosphate translocase component of the glucose-6-phosphatase system (EC 3.1.3.9), an enzyme system which is important for the control of blood glucose levels. The IC50 is 80 nM for kodaistatin A and 130 nM for kodaistatin C.

The use of neuromuscular blocking agents in the emergency department to facilitate tracheal intubation in the trauma patient: help or hindrance?

PURPOSE: The purpose of this study is to examine the relationship between the occurrence of a difficult intubation and (1) the use of neuromuscular blocking agents (NMB) and (2) the presence of airway injuries. It is a retrospective analysis of data from a trauma registry. MATERIALS AND METHODS: Registry records of patients (n = 160) who required emergent endotracheal intubation or establishment of a surgical airway over a 3.5-year period in the emergency department were reviewed. Risk factors for difficult intubations were identified and analyzed using multivariate logistic regression analysis. RESULTS: NMB were used in 75% of patients requiring intubation. Fifteen percent of the intubations were considered difficult. No association was found between the presence of airway injuries and difficult intubations; however, the use of succinylcholine was associated with a lower risk of difficult intubations compared with intubations where a nondepolarizing NMB was used. CONCLUSIONS: The use of succinylcholine may result in fewer difficult intubations in the trauma patient than when a nondepolarizing NMB is used. The presence of airway injuries did not appear to predispose to difficult intubations.

Influence of triple-lumen central venous catheters coated with chlorhexidine and silver sulfadiazine on the incidence of catheter-related bacteremia.

OBJECTIVE: To evaluate the efficacy of triple-lumen central venous catheters coated with a combination product of chlorhexidine and silver sulfadiazine (CSS) in reducing the incidence of local catheter infection and catheter-related bacteremia. DESIGN: Randomized, controlled trial. SETTING: The surgical intensive care units in a university hospital. PATIENTS: All patients who needed central venous catheterization were randomized to receive either an uncoated triple-lumen catheter (n = 157) or a catheter coated with CSS (n = 151). MAIN OUTCOME MEASURE: Catheters were removed when no longer needed or suspected as a cause of infection. The tip and a 5-cm segment of the intradermal portion of the catheter were cultured semiquantitatively. Blood cultures were obtained when clinically indicated. The remaining segment of catheters coated with CSS were cut and incubated on an agar plate with strains of Staphylococcus aureus and Enterococcus. Zone of inhibition was determined 24 hours later. Data were analyzed by survival and logistic multivariate regression methods. RESULTS: Catheters coated with CSS were effective in reducing the rate of significant bacterial growth on either the tip or intradermal segment (40%) compared with control catheters (52%; P = .04). However, there was no difference in the incidence of catheter-related bacteremia (3.8% [uncoated] vs 3.3% [coated]; P = .81). In vitro activity of catheters with CSS against S aureus was evident up to 25 days but activity against Enterococcus dissipated more quickly over time and was absent by day 4. The most common colonizing organisms were coagulase-negative staphylococcus and enterococcus. Variables that were associated with a significant amount of growth on the tip or intradermal segment were a duration of catheterization of longer than 7 days, jugular insertion site, and the absence of a CSS coating. The use of a guidewire when the catheter was removed was associated with a lower risk of significant bacterial growth. CONCLUSIONS: The use of CSS reduces the incidence of significant bacterial growth on either the tip or intradermal segments of coated triple-lumen catheters but has no effect on the incidence of catheter-related bacteremia. In this patient population, catheters coated with CSS provide no additional benefit over uncoated catheters.

Pulse oximetry in infants of < 1500 gm birth weight on supplemental oxygen: a national survey.

OBJECTIVE: To determine practices related to the use of pulse oximetry in monitoring infants of < 1500 gm birth weight on supplemental oxygen. STUDY DESIGN: A mailing list of all neonatal intensive care units with accredited Neonatal-Perinatal Fellowship programs was prepared. A questionnaire was prepared and mailed to collect information on the following: Method used for noninvasive monitoring of oxygen therapy, acceptable maximum and minimum arterial pulse oxygen saturation levels, high and low alarm settings, and whether oxygen was administered at a fixed or variable rate. RESULTS: A response rate of 70% to 85% was achieved for different items of the questionnaire. A wide variation exists regarding acceptable arterial pulse oxygen saturation levels and alarm settings. Many units accepted an arterial pulse oxygen saturation level of 100% or set the high alarm at 100%. CONCLUSION: There is a need for greater awareness of the potential for hyperoxemia that may result from accepting an arterial pulse oxygen saturation level of 100% or setting high alarms at 100%. We urge stricter adherence to published recommendations.

Arthrichitin. A New Cell Wall Active Metabolite from Arthrinium phaeospermum.

Arthrichitin (1), C(33)H(46)N(4)O(9), is a new cell wall active depsipeptide isolated from the fermentation broth of Arthrinium phaeospermum (HIL Y-903022). Its structure was elucidated on the basis of spectroscopic and chemical degradation studies. Arthrichitin consists of serine, beta-keto tryptophan, glutamic acid, and 2,4-dimethyl-3-hydroxydodecanoic acid units.

Profile of serum cholinesterase in systemic sepsis syndrome (septic shock) in intensive care unit patients.

Serum cholinesterase catalytic concentrations were estimated in 26 patients diagnosed as having systemic sepsis syndrome (septic shock) in the Intensive Care Unit (12 were admitted with the diagnosis of systemic sepsis syndrome while 14 patients developed the syndrome while in the unit) and in 66 normal, healthy subjects. The assay was performed for 7 consecutive days in the patient group. There was a very significant decrease in the level of cholinesterase in the patient group from the onset of the study as compared to the control group (P < 0.00001). This decrease remained during the course of the seven day study period, indicating hepatic dysfunction early in the diagnosis. When compared to other conventional liver function tests, serum cholinesterase seems to change earlier on in the diagnosis. Prothrombin time showed a pattern of change similar to that of serum cholinesterase. There was a significant relationship between the catalytic concentration of serum cholinesterase and the outcome of the systemic sepsis syndrome, the level being significantly lower in patients who died in comparison to those who lived. It seems that serum cholinesterase is a sensitive indicator of hepatic dysfunction in the systemic sepsis syndrome.