Milliliter Of Urine Research Articles

Risk Assessment for Polyomavirus Nephropathy Using Urine Cytology and the Detection of Decoy Cells

Risk Assessment for Polyomavirus Nephropathy Using Urine Cytology and the Detection of Decoy Cells

When Is a Chronic Wound Infected?

Humans are not germ free. In fact, the number of bacterial cells in our body exceeds the number of all our other cells. We live in relative harmonywith our bacterial flora. Therefore, the presence of bacteria alone is not an indication of infection. Intact skin is one of the major barriers to development of infection. A break in the skin; that is, a wound, opens the possibility of bacterial penetration and infection. The consequences of wound infection are formidable: delayed wound healing, extension of infection into muscle (necrosis) or bone (osteomyelitis) or bloodstream (sepsis), and increased mortality.1 Thus, determining when infection is present is critical to effective wound management. Onewould suppose that criteria fordiagnosingawound infection would be widely recognized, given the frequency of wound infections in the population. However, a reviewof the literature indicates that this is not the case. Considerable research over the years has simply elaborated how complicated this really is.2 What is clear is that acute wounds, such as surgical wounds or full-thickness burn injuries, differ considerably from chronic wounds, such as pressure ulcers, diabetic ulcers, venous stasis ulcer, or arterial ulcers.3 Moreover, it is increasingly clear that the symptoms/signs of infection differ among these chronic wounds themselves. How do we determine that a wound is infected? The diagnosis of awound infection requires two essential criteria: The presence of bacteria in the wound AND evidence that the bacteria is producing tissue damage (usually in the form of an inflammatory response). In the past 5 decades, a large amount of research has focused on the concept of “bacterial burden.” For example, a quantitative relationship between bacteria and urinary tract infection is widely accepted. A concentration of greater than 100,000 organisms per milliliter of urine is necessary to establish the diagnosis of pyelonephritis. If fewer than 100,000 organisms per milliliter are present, asymptomatic bacteriuria is present.4 The consequence of bacterial burden in acute wounds and in wounds healing by secondary intention is well established. Data

Metabolic precursors of surfactant disaturated-phosphatidylcholine in preterms with respiratory distress

Our objective was to study the metabolic precursors of surfactant disaturated-phosphatidylcholine (DSPC) in preterm infants with respiratory distress syndrome (RDS) on mechanical ventilation. We performed 46 DSPC kinetic studies in 23 preterms on fat-free parenteral nutrition and mechanical ventilation (birth weight = 1167 +/- 451 g, gestational age = 28.5 +/- 2.0 weeks). Eight infants received a simultaneous intravenous infusion of U(13)C-glucose and [16,16,16](2)H-palmitate, eight infants received U(13)C-glucose and (2)H(2)O, and seven received U(13)C-palmitate and (2)H(2)O. Surfactant DSPC kinetics were calculated from the isotopic enrichments of DSPC-palmitate from sequential tracheal aspirates and its metabolic precursors in plasma or urine. DSPC fractional synthesis rate (FSR) was 17 +/- 11, 21 +/- 16, and 15 +/- 6%/day from glucose, palmitate, and body water, respectively (P = 0.36). DSPC-FSR from U(13)C-glucose and (2)H(2)O were significantly correlated and yielded similar estimates (difference of -0.1 +/- 3%) (P = 0.91). The difference in the 15 infants receiving palmitate versus (2)H(2)O or palmitate versus glucose was +6.0 +/- 12%/day (P = 0.21). There was a significant correlation between DSPC-FSRs from plasma glucose and plasma FFA. The contribution of glucose versus palmitate to DSPC-FSR was 49 +/- 20% versus 51 +/- 20%, respectively. Plasma glucose and FFA showed similar contributions to DSPC-FSR in infants with RDS and fat-free parenteral nutrition. FSRs from (2)H(2)O or glucose were highly correlated.

The risk of bacteriuria and ureteric stent colonization in immune-compromised patients with double J stent insertion

To evaluate the influence of diabetes mellitus (DM), chronic renal failure (CRF), and malignancies on the rate of bacteriuria and double J ureteric stent bacterial colonization. One hundred and twenty patients were included in this prospective study. Midstream urine samples for culture were obtained before ureteric stent insertion. Patients with negative culture were given ciprofloxacin 500 mg orally q 12 h for 5 days as a prophylaxis. All the stents were removed or changed as indicated after having voided midstream urine sample for culture on the day of stent removal. Stents were sent for culture. Culture was obtained from the outer surface of the stent by gentle scraping with a sterile scalpel. Significant bacteriuria was defined as a count of colony-forming units per milliliter of urine of >10(5). The patients were between 20 and 74 years of age (mean 42.5 + or - 13) and the duration of stent insertion ranged between 14 and 120 days (52.5 + or - 7.2). In 29 patients (24.2%), double J stent bacterial colonization was positive (12 males and 17 females). Of these patients, 27 (22.5%) had positive urine cultures (11 males and 16 females). The most commonly isolated pathogen was Escherichia coli. DM, CRF, or malignancies showed a higher risk for bacteriuria and stent bacterial colonization. Immune-compromising diseases such as DM, CRF, and malignancies are proved to be risk factors for urinary tract infection and stent colonization in patients with ureteric stent insertion. Stent cultures are not needed as the same microorganisms grow in urine cultures.

Recurrent Urinary Tract Infection (UTI) in Women

Abstract Recurrent lower urinary tract infections (UTIs) are usually defined as two or more episodes of such infection occurring in the preceding 12 months. In most cases, such infections are the result of sexual habits and hygiene (e.g., women who are sexually active, especially those using diaphragms and/or spermatocides). A clean-catch or catheterized specimen for culture typically reveals greater than 100,000 organisms per milliliter of urine. The typical infecting organism is Escherichia coli. The route of infection is ascending from the perianal area and vagina via the urethra and into the bladder. However, in uncomplicated lower UTIs, there is complete clearing of bacteriuria and hematuria with appropriate antimicrobial therapy. In some cases, single-dose antimicrobial therapy after intercourse or at the onset of irritative voiding symptoms is adequate to control frequent recurrences of cystitis. Uncomplicated recurrent lower UTIs in women must be differentiated from “reinfection,” which may indicate causes such as a vesicovaginal or vesicoenteric fistula or a paravesical abscess with fistula to the bladder. Furthermore, “bacterial persistence” is defined as an infection with the same organism, typically from a site within the urinary tract, after the bacteriuria has resolved for at least several days and antimicrobial therapy has ceased. Causes of bacterial persistence include calculi, foreign bodies, urethral or bladder diverticula, infected urachal cyst, and postoperative changes such as a remaining ureteral stump that retains urine and results in stasis. In such patients with frequent recurrences and reinfections with the same bacteria, imaging is indicated to detect a treatable condition and monitor its progress. Compromised immunity needs attention to avoid longstanding morbidity. Vaccine developed will lead more prevention in future.

Simultaneous determination of methamphetamine, 3,4-methylenedioxy-N-methylamphetamine, 3,4-methylenedioxy-N-ethylamphetamine, N,N-dimethylamphetamine, and their metabolites in urine by liquid chromatography-electrospray ionization-tandem mass spectrometry

A liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method was developed and validated for the simultaneous detection and quantification of seven amphetamine derivatives (amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxy-N-amphetamine (MDA), 3,4-methylenedioxy-N-methamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), N,N-dimethylamphetamine (DMA), and N,N-dimethylamphetamine-N-oxide (DMANO)) in human urine. Seven deuterium-labeled compounds were prepared for use as internal standards to quantify the analytes. One milliliter of urine was combined with 1 mL of 0.2 M sodium carbonate buffer solution (pH 9.0) before solid phase extraction (SPE). An Oasis HLB SPE column followed by chromatographic separation on a Capcell Pak C18 MG-II column (150 x 2.0 mm I.D., 5 microm) and electrospray mass spectrometry with multiple reaction monitoring were used for selective and sensitive detection. The use of ammonium formate (5 mM, pH adjusted to 4.0 with formic acid, Solvent A) and acetonitrile (Solvent B) as the mobile phase at a flow rate of 230 microL/min was found to be the most effective for the separation. The linear ranges were 5.0-1000 ng/mL for AP, MDA, MDMA, MDEA, DMA, and DMANO and 10.0-1000 ng/mL for MA, with good correlation coefficients (r2 > 0.996). The intra-day, inter-day, and interperson precisions were within 14.6%, 12.1% and 15.5%, respectively. The intra-day, inter-day, and interperson accuracies were between -11.6 and 9.0%, -7.9 and 2.3%, and -13.2 and 4.3%, respectively. The limits of detection (LODs) for each analytical compound were lower than 1.95 ng/mL. The recovery ranged from 72.3 to 103.3%. The applicability of the developed method was examined by analyzing several urine samples from confirmed drug abusers.

Short- versus long-course antibiotic therapy for acute pyelonephritis in adolescents and adults: A meta-analysis of randomized controlled trials

Background: Despite the high incidence of acute pyelonephritis in the community setting, there is no consensus on the optimal duration of treatment. A potential reduction in the duration of the administered antibiotic regimens could contribute to avoiding further development of antimicrobial resistance.Objective: The aim of this meta-analysis was to compare short-course (7- to 14-day) with long-course (14- to 42-day) treatment with the same antibiotic regimens, in terms of the effectiveness and tolerability, in acute pyelonephritis.Methods: We searched PubMed, Cochrane Central Register of Controlled Trials, and SCOPUS (January 1966-March 2008) to identify and extract data from randomized controlled trials (RCTs) comparing the effectiveness and toxicity of short- versus long-course regimens. Additionally, references of studies were searched. A publication was included if: it was an RCT; involved adult and/or adolescent patients with acute pyelonephritis; compared regimens with the same antibiotic, at the same daily dosage, that were administered for differing durations (a short course and a long course lie, no absolute time cutoff (in days) was employed; rather, the duration of one regimen compared with another defined short- vs long-course]); and reported data regarding clinical success, bacteriologic efficacy, relapses, recurrences, and adverse events and/or patient withdrawals due to adverse events. Trials with a mixed population, including patients with acute pyelonephritis as a subset, were also included in the meta-analysis. Efficacy was assessed by evaluating clinical success, defined as resolution of symptoms and signs at the test-of-cure visit, and bacteriologic efficacy, defined as yielding sterile urine cultures or positive cultures with <103 colony-forming units per milliliter of urine at the test-of-cure visit. Tolerability was assessed by extracting data for adverse events.Results: According to our initial search, 205, 136, 179, and 73 potentially relevant articles were retrieved from PubMed, Cochrane Central Register of Controlled Trials, SCOPUS, and references of evaluable trials, respectively. Four RCTs were eligible for inclusion in the meta-analysis. Significant differences were not found between the short- and long-course treatment of acute pyclonephritis in terms of clinical success (odds ratio [OR], 1.27; 95% CI, 0.59-2.70), bacteriologic efficacy (OR, 0.80; 95% CI, 0.13-4.95), and relapse (OR, 0.65; 95% CI, 0.08-5.39). Also, significant differences were not found between the short- and long-course treatments regarding adverse events (OR, 0.64; 95% CI, 0.33-1.25), withdrawals due to adverse events (OR, 0.65; 95% CI, 0.28-1.55), and recurrences (OR, 1.39; 95% CI, 0.63-3.06).Conclusion: This meta-analysis failed to identify any significant differences, with regard to effectiveness and tolerability, between short- and long-course treatment with the same antibiotic.

Similar Exposure to a Tobacco-Specific Carcinogen in Smokeless Tobacco Users and Cigarette Smokers

Smokeless tobacco has been proposed as a reduced risk substitute for smoking, but no large studies have investigated exposure to the powerful carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in smokeless tobacco users versus smokers. The purpose of this study was to carry out such a comparison. Levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronides (total NNAL), a biomarker of NNK exposure, and cotinine, a biomarker of nicotine exposure, were quantified in the urine of 420 smokers and 182 smokeless tobacco users who were participants in studies designed to reduce their use of these products. The measurements were taken at baseline, before intervention. Levels of total NNAL per milliliter of urine were significantly higher in smokeless tobacco users than in smokers (P < 0.0001). When adjusted for age and gender, levels of total NNAL per milligram of creatinine were also significantly higher in smokeless tobacco users than in smokers (P < 0.001). Levels of cotinine per milliliter of urine and per milligram of creatinine were significantly higher in smokeless tobacco users than in smokers (P < 0.001). These results show similar exposures to the potent tobacco-specific carcinogen NNK in smokeless tobacco users and smokers. These findings do not support the use of smokeless tobacco as a safe substitute for smoking.

Chelation of urinary cadmium with ammonium pyrrolidine dithio-carbamate prior to determination by tungsten-coil inductively coupled plasma atomic emission spectrometry

Cadmium in the urine samples of patients with age-related disease forms a complex with a chelating agent, ammonium pyrrolidine dithio-carbamate, and the complex is extracted with methyl isobutyl ketone. One milliliter of urine provides three separate 200-μl aliquots of extract, so a preconcentration factor of 5/3 is observed. In this manner, the Cd is effectively separated from the complex urine matrix. An internal standard, Bi, is added to improve both precision and accuracy. The extracts are analyzed by inductively coupled plasma atomic emission spectrometry using a tungsten-coil as an electrothermal vaporizer. A 20-μl aliquot of the extract is injected directly onto the coil. Two Cd atomic emission lines are observed simultaneously: 228.8 nm and 226.5 nm. The limits of detection at these wavelengths are 0.04 and 0.2 μg/l, respectively. Without the extraction technique, the detection limit is 0.4 μg/l at the 228.8-nm line. With the internal standard technique, the accuracy as measured with a urine standard reference material is 98%. Six urine samples collected from patients with age-related diseases are found to contain Cd levels in the range 0.9 to 4.1 μg/l. The precision associated with the measurement of these real samples is 6.2% relative standard deviation. The technique provides off-wavelength background correction and simultaneous determination at two different wavelengths, so samples that are limited in volume can still be analyzed with a high degree of confidence.

Asymptomatic bacteriuria in sickle cell disease: a cross-sectional study

BackgroundIt is known that there is significant morbidity associated with urinary tract infection and with renal dysfunction in sickle cell disease (SCD). However, it is not known if there are potential adverse outcomes associated with asymptomatic bacteriuria (ASB) infections in sickle cell disease if left untreated. This study was undertaken to determine the prevalence of ASB, in a cohort of patients with SCD.MethodsThis is a cross-sectional study of patients in the Jamaican Sickle Cell Cohort. Aseptically collected mid-stream urine (MSU) samples were obtained from 266 patients for urinalysis, culture and sensitivity analysis. Proteinuria was measured by urine dipsticks. Individuals with abnormal urine culture results had repeat urine culture. Serum creatinine was measured and steady state haematology and uric acid concentrations were obtained from clinical records. This was completed at a primary care health clinic dedicated to sickle cell diseases in Kingston, Jamaica. There were 133 males and 133 females in the sample studied. The mean age (mean ± sd) of participants was 26.6 ± 2.5 years. The main outcome measures were the culture of ≥ 105 colony forming units of a urinary tract pathogen per milliliter of urine from a MSU specimen on a single occasion (probable ASB) or on consecutive occasions (confirmed ASB).ResultsOf the 266 urines collected, 234 were sterile and 29 had significant bacteriuria yielding a prevalence of probable ASB of 10.9% (29/266). Fourteen patients had confirmed ASB (prevalence 5.3%) of which 13 had pyuria. Controlling for genotype, females were 14.7 times more likely to have confirmed ASB compared to males (95%CI 1.8 to 121.0). The number of recorded visits for symptomatic UTI was increased by a factor of 2.5 (95% CI 1.4 to 4.5, p < 0.005) but serum creatinine, uric acid and haematology values were not different in patients with confirmed ASB compared with those with sterile urine. There was no association with history of gram negative sepsis.ConclusionASB is a significant problem in individuals with SCD and may be the source of pathogens in UTI. However, further research is needed to determine the clinical significance of ASB in SCD.

Preliminary study on differentiation of Leptospira grippotyphosa and Leptospira sejroe from other common pathogenic leptospiral serovars in canine urine by polymerase chain reaction assay.

A multiplex polymerase chain reaction (PCR) method using primer sets of G1/G2 and B64-I/B64-II was validated to detect pathogenic leptospira serovars from canine urine samples. The PCR method was found to be specific and sensitive with a detection limit of 100 cells of Leptospira icterohaemorrhagiae per milliliter of urine. The primer set previously designated and erroneously transcribed B64-I/B64-II amplified a DNA fragment of 352 base pairs from Leptospira grippotyphosa and Leptospira sejroe but not from Leptospira autumnalis, Leptospira bratislava, Leptospira canicola, Leptospira hardjo, Leptospira icterohaemorrhagiae, and Leptospira pomona. From 100 diagnostic canine urine samples, 5 were found positive for Leptospira grippotyphosalsejroe with a PCR product of 352 base pairs and 6 were positive for other pathogenic leptospira serovars with a PCR product of 285 base pairs. One 285-base pair product was sequenced and found to be 99.3% homologous to the G1/G2 PCR fragment sequence reported previously. All 352-base pair PCR products of clinical samples and pure cultures of L. grippotyphosa and L. sejroe were sequenced. The 352-base pair fragment sequences of L. grippotyphosa and L sejroe were identical. Only 2 base pairs were found different between the sequences from pure cultures and those from clinical samples. Serum samples from 3 positive cases that generated a PCR product of 352 base pairs were tested by the microscopic agglutination test, and 2 were found to be positive for L. grippotyphosa (1:10,240 and 1:5,120), 1 was positive for L. grippotyphosa (1:320) or L. icterohaemorrhagiae (1:320). The results of this study suggest that the multiplex PCR with the primer set G1/G2 and the erroneously transcribed B64-I/B64-II may be able to differentiate L. grippotyphosa or L. sejroe from other pathogenic leptospira serovars commonly tested for in Canadian diagnostic laboratories.

Investigation of CD68 positive monocytes/macrophage(CD68+ Mo/M phi) in urine and infiltrated tissue of various kidney diseases in children

In order to investigate the participation of monocytes/macrophages(Mo/M phi) in the progression of various kidney diseases of children, Mo/M phi in urine and that infiltrating renal tissue were both measured as the number of CD68 positive Mo/M phi (CD68+ Mo/M phi), using anti-CD68 antibody. The number of CD68+ Mo/M phi infiltrating in one glomerulus was significantly higher in Henoch-Schönlein purpura nephritis(HSPN) (p < 0.01) in comparison with that in minimal change nephrotic syndrome(MCNS) (p < 0.01), and a high tendency was found in IgA nephropathy (IgAN), proliferative glomerulonephritis (non-IgAN), focal segmental glomerulosclerosis(FSGS) and membranoproliferative glomerulonephritis (MPGN), respectively. The number of CD68+ Mo/M phi infiltrating one mm2 of tubulo-interstitium area was significantly higher in HSPN(p < 0.05), FSGS(p < 0.01), Alport's syndrome(p < 0.01), respectively, than that in MCNS. The number of CD68+ Mo/M phi in one milliliter of urine correlated significantly with both that infiltrating the glomerulus and the tubulo-interstitium(both p < 0.01). Moreover the number of urine CD68+ Mo/M phi in a clinically active stage was significantly higher than that in an inactive stage in the AGN(p < 0.05), IgAN(p < 0.05), HSPN(p < 0.05), non-IgAN(p < 0.01) and MPGN groups(p < 0.05), respectively. From these results, 1) It was suggested that the Mo/M phi infiltrating renal tissue participated in the development of various kidney diseases. 2) It was predicted that CD68+ Mo/M phi in urine reflected both the number of Mo/M phi infiltrating the glomerulus and that in the tubulo-interstitium. 3) It was suggested that the number of CD68+ Mo/M phi in urine indicated clinical activity in proliferative glomerulonephritis groups of children.

Liquid Chromatography-Electrospray Ionization Mass Spectrometry for the Detection of Lysergide and a Major Metabolite, 2-Oxo-3-Hydroxy-LSD, in Urine and Blood

A method is presented for the quantitative measurement of lysergide (LSD) and its metabolite 2-oxo-3-hydroxy-LSD (O-H-LSD) in urine and blood. O-H-LSD has been reported to have urinary concentrations many times higher than LSD. Measuring its presence in urine would significantly extend the detection time for confirming LSD abuse. A single-step liquid-liquid extraction was performed on 5-mL urine samples prior to separation by gradient liquid chromatography (LC). Electrospray ionization was used to produce the positively charged ions of O-H-LSD, 2-oxo-3-hydroxy-LAMPA (O-H-LAMPA, internal standard), LSD, and iso-LSD. Varying the orifice voltage in the intermediate-pressure region of the source generated the fragmentation necessary to produce qualifying ions. Selected ion monitoring allowed detection limits of 400 pg/mL and 100 pg/mL for O-H-LSD and LSD, respectively. The method was linear for O-H-LSD from 400 to 8000 pg/mL and for LSD from 100 to 6000 pg/mL. LSD-positive samples (n = 9) analyzed by the liquid chromatography-mass spectrometry method were found to contain mean concentrations of 6378 pg/mL O-H-LSD (332-21371 pg/mL) and 844 pg/mL LSD (177-2456 pg/mL). O-H-LSD urinary concentrations were between 0.9 and 19.8 times higher than LSD (mean = 10.2). Whole-blood samples were also analyzed following additional sample cleanup. LSD was measured in the blood samples, but no O-H-LSD was detected. Enzymatic hydrolysis was carried out on LSD-positive samples (n = 6) to evaluate the existence of conjugated O-H-LSD. Beta-glucuronidase from Helix pomatia was incubated with urine samples at 37 degrees C, pH 5.2 for 24 h. At an enzymatic activity of approximately 4000 units per milliliter of urine, no significant (p = 0.05) difference was seen between hydrolyzed and nonhydrolyzed samples suggesting an absence of O-H-LSD-glucuronic acid conjugation.

Perioperative lower urinary tract infections and deep sepsis in patients undergoing total joint arthroplasty.

Deep sepsis in the involved joint after hip or knee arthroplasty may be the result of hematogenous seeding from a remote infectious source. This mechanism has been used to explain the well-documented association between postoperative urinary tract infections and subsequent joint infection after hip or knee arthroplasty. However, it is unclear whether there is an association between preoperative bacteriuria and deep prosthetic infection. The purpose of this review is to identify perioperative risk factors associated with bacteriuria that have a positive correlation with deep joint sepsis following total hip or knee arthroplasty. The classic symptoms of dysuria, urgency, and frequency seen with urinary tract infections are often absent in the elderly despite the presence of urine coliforms; in these patients, pyuria (as indicated by the presence of more than 1x10(3) white blood cells per milliliter of noncentrifuged urine) may be used as a preliminary screening criterion. If there are irritative symptoms, the presence of more than 1x10(3) bacteria per milliliter of urine should be regarded as indicative of a urinary tract infection. If there is bacteriuria without symptoms of urinary irritation or obstruction, the current literature supports proceeding with total joint arthroplasty and treating those patients with urine colony counts greater than 1x10(3)/mL with an 8- to 10-day postoperative course of an appropriate oral antibiotic. Postponement of total joint surgery should be considered if preoperative evaluation reveals symptoms related to obstruction of the urinary pathway. Irritative symptoms in combination with a bacterial count greater than 1x10(3)/mL should also serve as an indication to postpone surgery. To diminish postoperative urinary tract infection, a bladder catheter should be inserted immediately preoperatively and removed within 24 hours of surgery to diminish the risk of urinary retention, which has been shown to increase the likelihood of a postoperative urinary tract infection.

Quantification of testosterone and epitestosterone in human urine by capillary liquid chromatography

A capillary-liquid chromatography (LC) method was developed for the quantification of the endogenous steroids testosterone and epitestosterone in human urine. One milliliter of urine was used for the overall method. Free testosterone was first separated by liquid–liquid extraction with n-pentane at pH 7. Glucuronides of testosterone and epitestosterone were enzymatically hydrolyzed and the free compounds were extracted with n-pentane at pH 11. A capillary column switching system with a low back pressure precolumn (PC) was used for fast loading of large sample volumes (20 μL). Chromatographic separation was carried out on a 15 cm×300 μm inner diameter (i.d.) column, packed with 3 μm Hypersil BDS-C18 at a flow rate of 4 μL/min with isocratic elution and UV absorbance detection (240 nm). Limit of detection for free testosterone was established at 0.5 ng/mL. Limits of detection were established at 1.5 and 3.2 ng/mL for testosterone and epitestosterone, respectively, after being hydrolysed from their glucuronides. Good reproducibility and robustness were observed through the entire calibration range (up to 250 ng/mL). © 2001 John Wiley & Sons, Inc. J Micro Sep 12: 623–629, 2000

Electrochemical study of mefexamide at glassy-carbon electrodes and its determination in urine by differential pulse voltammetry

The electrochemical oxidation of mefexamide N-[2-(diethylamino)ethyl]-2-(4-methoxyphenoxy)acetamide was investigated using cyclic, linear scan and rotating disk voltammetry at glassy-carbon electrodes. The value of pKa (9.01) was determined by the potentiometric method. In cyclic voltammetry, in neutral media, the compound shows two electrochemical irreversible oxidation peaks (both 2e−), Ox1 and Ox2. A new redox couple Red3/Ox3, formed as a result of the oxidation Ox1 peak, followed for an irreversible chemical reaction, appears on the reverse negative sweep. In acidic media, only the Ox1 peak was observed. The most defined peaks were obtained in 0.040 M Britton–Robinson buffer (pH 6.0) and 0.010 M sulfuric acid with 0.10 M sodium sulfate. The Ox1 and Ox2 peak currents were diffusion-controlled, showing an adsorption effect for low mefexamide concentrations (1.0×10−4 M) and calibration plots at 20 mV s−1, being linear in the range 5.0×10−5–5.0×10−4 M. The limiting currents in a rotating disk electrode were mass transport controlled for rotation speeds lower than 3000 rpm. The anodic charge transfer coefficient, the mass-transport rate constant, the diffusion coefficient and the charge-transfer conditional constant were determined. Also, a method for the electrochemical determination of mefexamide in human urine was developed using differential pulse voltammetry, in 0.040 M Britton–Robinson buffer (pH 6.0), being extracted with dichloromethane. The standard addition method was applied. The detection limit was 0.8 μg of mefexamide per milliliter of urine. The statistical validation reveals that the method is free from significant systematic errors.

Determination of buprenorphine and norbuprenorphine in urine and hair by gas chromatography-mass spectrometry.

Buprenorphine, which is used in France as a substitution drug for opioid addiction, is widely abused, and several fatal cases have been reported. In order to confirm a recent intoxication or to establish retrospectively chronic abuse, a simple and reliable gas chromatographic-mass spectrometric method was developed and validated for quantitation of buprenorphine and its active metabolite norbuprenorphine in urine and hair. Two milliliters of urine or 50 mg of pulverized hair was submitted to a pretreatment (enzymatic hydrolysis for urine and decontamination with dichloromethane followed by incubation in 0.1 M HCI for hair). Buprenorphine-d4 was chosen as the internal standard. Selective solid-phase extraction with Bond Elut Certify columns provided recoveries higher than 85% for urine and 43% for hair. By using a mixture of MSTFA/TMSIM/TMCS (100:2:5), buprenorphine and norbuprenorphine produced stable silylated derivatives. The detection was carried out with a quadrupole mass detector working in El selected ion monitoring mode. Ions at m/z 450 and 468 were chosen for the quantitation of buprenorphine and norbuprenorphine, respectively (m/z 454 was used for the internal standard). Limits of quantitation were 0.25 and 0.20 ng/mL, respectively, for buprenorphine and norbuprenorphine in urine and 0.005 ng/mg for the two compounds in hair. Calibration curves were linear from 0 to 50 ng/mL in urine and from 0 to 0.4 ng/mg in hair. Between-day and within-day precisions were less than 8.4% in hair and 6.1% in urine for both molecules in all cases. This method was applied to urine and hair samples collected from patients in a withdrawal treatment program and demonstrated its good applicability in routine analysis and its benefit for clinicians. This technique, which requires instruments already available to many toxicology laboratories, offers an attractive alternative to more sophisticated techniques.

Simultaneous extraction of selected benzodiazepines and benzodiazepine-glucuronides from urine by immunoadsorption.

A rapid and selective cleanup procedure based on immunoadsorption is described for the simultaneous extraction of diazepam and its free or glucuronidated metabolites nordiazepam, temazepam, and oxazepam from urine. The method can also be used for the extraction of lorazepam and lorazepam-glucuronide. Because the samples do not have to be hydrolyzed before extraction, valuable information is preserved. With the exception of lorazepam-glucuronide, recoveries between 86 and 100% were obtained at spiking levels up to 200 ng of benzodiazepine or glucuronide per milliliter of urine. Using methanol/water (90:10, v/v) as an eluent, the immunoadsorber could be used at least 20 times. High-performance liquid chromatograms of urine samples from patients receiving low therapeutic dosages of diazepam or lorazepam are shown to demonstrate the high purity of the extracts.

Bacterial etiologic agents of urinary tract infection in children in the Islamic Republic of Iran

The bacterial agents of urinary tract infections were studied in 1650 children under 12 years of age between April 1993 and March 1995. It was found that 25.8% [425/1650] of infants and children showed bacteriuria [&gt;10 [5] bacteria per millilitre of urine]. Escherichia coli was responsible for 71.0% of all infections. Infections caused by Proteus spp. were predominantly found in boys. Girls showed a higher prevalence of infection [35.3%] than boys [18.3%], which was statistically highly significant [P &lt; 0.001]. The most commonly isolated bacteria were partially or totally sensitive to the aminoglycosides, chloramphenicol and nalidixic acid

Electrochemical studies of ethamivan at glassy-carbon and platinum electrodes and its determination in urine by differential pulse voltammetry

The electrochemical oxidation of ethamivan ( N, N-diethyl-4-hydroxy-3-methoxy-benzamide) was investigated using cyclic, linear scan and differential pulse voltammetry at glassy-carbon and platinum stationary electrodes, and rotating disk voltammetry. The values of p K a , 8.98 and 9.03, were determinated by potentiometric and spectrophotometric methods. The compound showed an electrochemically reversible two electrons oxidation peak followed by an irreversible chemical reaction, and produced a new redox couple. The best defined peaks were obtained in 0.05 M sulphuric acid or 0.1 M hydrochloric acid at 0.87, 0.55 and 0.61 V (vs. Ag/AgCl/3 M KCl). The peak currents in cyclic voltammetry and the limiting current at a rotating disk electrode are diffusion-controlled. Using rotating disk voltammetry the mass-transport rate constant was 5.26 × 10 −3cms −1 for a rotation frequency of 20.34 Hz, the diffusion coefficient was 6.5 × 10 −6 cm 2 s −1, the charge-transfer conditional rate constant was 1.2 × 10 −3cm s −1 and the charge transfer coefficient (β) was 0.91. By linear scan voltammetry calibration plots were linear in the range 7.0 × 10 −5−8.0 × 10 −4M at the Pt electrode and in the range 4.0 × 10 −5 − 1.0 × 10 −3M at the GCE in 0.05 M sulphuric acid at 50 mV s −1. A method was also developed for the electrochemical determination of ethamivan in human urine using differential pulse voltammetry with prior drug separation with C 18 cartridges (Sep-Pak, Waters). The mean recovery was 92 ± 6% ( n = 8). The standard addition method was applied. The relative standard deviation was lower than 9% (samples of 15 μg ml −1 ethamivan). The detection limit was 4 μg per milliliter of urine.