Ali Bazzi

Determination of toxic and essential elements in children's blood with inductively coupled plasma-mass spectrometry.

Recent studies have suggested that low blood lead level, less than 50 microg L(-1), can influence the neurobehavioral performance of children. In addition, nutritional deficiencies in some essential elements may increase the toxicity of lead, and some essential elements may influence the blood concentrations of lead and other toxic metals. These findings, coupled with the scarcity of available data on some elements in childrens blood and the introduction of methylcyclopentadienyl manganese tricarbonyl (MMT) to gasoline, accentuate the need to monitor the concentrations of lead, manganese, and other heavy metals and essential elements in childrens blood. This study reports on the multi-element analysis of blood of South African school children using inductively coupled plasma-mass spectrometry (ICP-MS). The sample preparation consisted of a nitric acid/hydrogen peroxide open digestion and subsequent dilution with MilliQ water. The accuracy and precision were evaluated from quintuplet analyses of Seronorm trace elements whole blood reference material and human blood samples. Concentrations of lead, arsenic, manganese, copper, zinc, selenium, cobalt, and chromium in the blood of South African school children were determined. The average values were: lead 56.4 microg L(-1), arsenic 1.53 microg L(-1), manganese 8.48 microg L(-1), copper 1195 microg L(-1), zinc 3431 microg L(-1), selenium 176 microg L(-1), cobalt 0.80 microg L(-1), and chromium 1.25 microg L(-1). The level of lead was in line with some reported lower concentrations. The concentrations of arsenic and manganese were generally lower than those found in the literature. The concentrations of cobalt, copper, selenium, and chromium were higher than those found in other studies, whereas that of zinc was lower.

Prophylactic Antibiotic Choice and Risk of Surgical Site Infection After Hysterectomy.

OBJECTIVE: To evaluate associations between prophylactic preoperative antibiotic choice and surgical site infection rates after hysterectomy. METHODS: A retrospective cohort study was performed of patients in the Michigan Surgical Quality Collaborative undergoing hysterectomy from July 2012 to February 2015. The primary outcome was a composite outcome of any surgical site infection (superficial surgical site infections or combined deep organ space surgical site infections). Preoperative antibiotics were categorized based on the recommendations set forth by the American College of Obstetricians and Gynecologists and the Surgical Care Improvement Project. Patients receiving a recommended antibiotic regimen were categorized into those receiving &bgr;-lactam antibiotics and those receiving alternatives to &bgr;-lactam antibiotics. Patients receiving nonrecommended antibiotics were categorized into those receiving overtreatment (excluded from further analysis) and those receiving nonstandard antibiotics. Multivariable logistic regression models were developed to estimate the independent effect of antibiotic choice. Propensity score matching analysis was performed to validate the results. RESULTS: The study included 21,358 hysterectomies. The overall rate of any surgical site infection was 2.06% (n=441). Unadjusted rates of “any surgical site infection” were 1.8%, 3.1%, and 3.7% for &bgr;-lactam, &bgr;-lactam alternatives, and nonstandard groups, respectively. After adjusting for patient and operative factors within clusters of hospitals, compared with the &bgr;-lactam antibiotics (reference group), the risk of “any surgical site infection” was higher for the group receiving &bgr;-lactam alternatives (odds ratio [OR] 1.7, confidence interval [CI] 1.27–2.07) or the nonstandard antibiotics (OR 2.0, CI 1.31–3.1). CONCLUSION: Compared with women receiving &bgr;-lactam antibiotic regimens, there is a higher risk of surgical site infection after hysterectomy among those receiving a recommended &bgr;-lactam alternative or nonstandard regimen.

Chemical Speciation of Dissolved Copper in Saginaw Bay, Lake Huron, with Square Wave Anodic Stripping Voltammetry

Although chemical speciation studies of copper in sea and estuarine waters have received extensive attention, few investigations have been reported dealing with freshwater eco-systems. This work represents the first set of accurate and comprehensive data on chemical speciation of dissolved copper in Saginaw Bay, Michigan, obtained with square wave anodic stripping voltammetry (SWASV) at the hanging mercury drop electrode (HMDE). The average dissolved copper concentration in the bay was 10.1 nM (0.642 μg/L), and the complexing capacity and logK’ values ranged from 192 to 417 nM and 7.52 to 9.63, respectively, implying extensive chelation by natural organic ligands. Both parameters display seasonal and site location variations. This study shows that the total dissolved copper exists predominantly (> 98%) as strong organic complexes with the remainder (< 2%) as labile copper.

Chlorhexidine-Alcohol Compared with Povidone-Iodine for Preoperative Topical Antisepsis for Abdominal Hysterectomy

OBJECTIVE To compare preoperative chlorhexidine-alcohol topical antiseptic agent with povidone-iodine in patients undergoing abdominal hysterectomy for benign indications. METHODS A retrospective cohort study of patients undergoing abdominal hysterectomy from July 2012 to February 2015 in the Michigan Surgical Quality Collaborative was performed. The primary exposure was the use of chlorhexidine-alcohol or povidone-iodine. The primary outcome was surgical site infection within 30 days. Multivariable logistic regression and propensity score matching analysis were done to estimate the independent association of skin antiseptic choice on the rate of surgical site infection. RESULTS Of the total 4,259 abdominal hysterectomies included, chlorhexidine-alcohol was used in 70.5% (n=3,005) and povidone-iodine in 29.5% (n=1,254) of surgeries. The overall unadjusted rate of any surgical site infection was 2.9% (95% CI 2.5-3.5; n=124). The unadjusted rate of surgical site infection 2.6% (95% CI 2.1-3.3; n=79) for chlorhexidine-alcohol and 3.6% (95% CI 2.7-4.8; n=45; P=.09) for the povidone-iodine group. Using multivariate logistic regression and adjusting for differences between populations in patient demographic factors (age and body mass index), medical comorbidities (American Society of Anesthesiologists class and diabetes status), perioperative variables (estimated blood loss, surgical time, intraoperative adhesions, and antibiotic categories), and hospital characteristics (bed size and teaching status), we estimate that patients receiving chlorhexidine-alcohol had 44% lower odds of developing a surgical site infection (adjusted odds ratio 0.56, 95% CI 0.37-0.85, P=.01). Propensity score matching (one to one) yielded 808 patients in the chlorhexidine-alcohol group and 845 patients in the povidone-iodine group. In the matched groups, the rate of surgical site infection was 1.5% (95% CI 0.8-2.6; n=12) for the chlorhexidine-alcohol group and 4.7% (95% CI 3.5-6.4; n=40) for the povidone-iodine group (P<.001). CONCLUSION In abdominal hysterectomy performed for benign indications, chlorhexidine-alcohol-based skin antisepsis is associated with overall lower odds of surgical site infection compared with povidone-iodine.

Indirect voltammetric and atomic absorption spectrometric determination of caffeine

Two methods are described for the determination of caffeine, based on the formation of a caffeine-phosphomolybdate complex, decomposition of the complex and measurement of the equivalent molybdate by either differential-pulse polarography or atomic absorption spectrometry. Calibration graphs with a linearity range of at least 2–16 µg ml–1 of caffeine in the final solution were obtained. The relative standard deviation is approximately 2% for both methods. The methods were applied successfully to the determination of caffeine in some analgesics.

Indirect determination of thallium by differential-pulse polarography.

The method is based on the separation of Tl(I) as Tl(2)HPMo(12)O(40), stripping of the molybdate, and measurement of the peak current in differential-pulse polarography of the molybdenum. The calibration graph is linear over the range 2-12 ppm of thallium. The relative standard deviation is 1.2% (7 replicates each containing 500 microg of thallium). The current due to reduction of the molybdenum is three times that for reduction of the equivalent amount of Tl(I) in the thallous phosphomolybdate precipitate, making the indirect approach more sensitive than direct polarographic determination of the Tl(I).

Differential pulse polarographic determination of orthophosphate in nonaqueous media

Abstract The method is based on the polarographic behavior of 12-tungstophosphoric acid in nonaqueous media at the DME utilizing the differential pulse polarographic technique. In this procedure, orthophosphate is converted to 12-tungstophosphoric acid H3 PW 12 O 40 by reacting with tungstate under acidic conditions and at 100°C. The H3 PW 12 O 40 is extracted into 1-pentanol and its polarographic measurement is made in 1-pentanol-ethanoi mixture containing sodium perchlorate as supporting electrolyte. The differential pulse polarogram of H3 PW 12 O 40 in this solution shows three peaks between 0.00 and -0.90 V vs. Ag/ AgCl. The most cathodic peak at -0.78 V exhibited the highest peak current value and was used for the analytical measurement. A linear calibration graph in the range 0.10 - 5.00 pg/ml P in the final solution was obtained. The method has a relative standard deviation of 0.90% at the 4 pg/ml P level and 1.32% at the 1 μg/ml P level in the final solution. Arsenate, borate and silicate do not i...