Biomedical subjects

Alice Wells

Publications and source records attributed to Alice Wells.

15 recordsLinked to original sources

PubMed2006

False-positive serum tricyclic antidepressant concentrations using fluorescence polarization immunoassay due to the presence of hydroxyzine and cetirizine.

A recent report indicates that hydroxyzine and its active metabolite cetirizine interfere with the PENTINA carbamazepine assay. The potential interference of hydroxyzine and cetirizine with the fluorescence polarization immunoassay (FPIA) and CEDIA assay of carbamazepine as well as with the fluorescence polarization immunoassay of tricyclic antidepressants (TCA) was studied. Aliquots of drug-free serum pools were supplemented with various concentrations of hydroxyzine and cetirizine representing therapeutic, mild to moderate toxic as well as very toxic concentrations. Then apparent carbamazepine and TCA concentrations were measured by immunoassays. Although no interference of hydroxyzine and cetirizine was observed with carbamazepine assays (FPIA and CEDIA), significant apparent TCA concentrations were observed when aliquots of drug-free serum were supplemented with hydroxyzine or cetirizine. Mathematical formula was devised to predict hydroxyzine and/or cetirizine concentration in serum based on observed apparent TCA levels. Hydroxyzine and cetirizine also falsely increased total TCA values when aliquots of serum pool prepared from patients receiving TCA were further supplemented with these drugs. In conclusion, hydroxyzine and cetirizine do not interfere with the FPIA and CEDIA carbamazepine assays but interfere with the measurement of total TCA using the FPIA.

Antidepressive Agents, Tricyclic↗

PubMed2006

Effect of plantain on therapeutic drug monitoring of digoxin and thirteen other common drugs.

INTRODUCTION: Plantain, a herbal remedy, has been reported to interfere with therapeutic drug monitoring of digoxin. We evaluated three commercially available plantain products for potential interference with therapeutic drug monitoring of digoxin and 13 other common drugs. METHOD: Dry content of plantain capsule or plantain leaf was extracted with either methanol or ethanol:water (60:40 by volume), added to drug-free serum and apparent digoxin was measured by both fluorescence polarization immunoassay and microparticle enzyme immunoassay. Using immunoassays, we also measured apparent concentrations of 13 other drugs (tobramycin, procainamide, tricyclic antidepressants, quinidine, carbamazepine, phenytoin, theophylline, valproic acid, amikacin, gentamycin, phenobarbital, salicylate and acetaminophen [paracetamol]) due to the presence of plantain. In separate experiments, a serum pool prepared from patients receiving digoxin was further supplemented with plantain and observed digoxin values were compared with original digoxin concentration. The presence of any cardiac glycoside in plantain was also investigated using thin layer chromatography (TLC). RESULTS: We observed no apparent digoxin in the presence of plantain in serum. Moreover, when aliquots of digoxin serum pool were supplemented with various amounts of plantain, the observed digoxin concentrations in the presence of plantain compared well with original digoxin concentration. TLC analysis did not show the presence of either digoxin or digitoxin in plantain products studied. Moreover, plantain did not affect immunoassay results of the 13 other drugs studied. CONCLUSIONS: The plantain products studied did not interfere with therapeutic drug monitoring of digoxin as well as 13 other commonly monitored drugs.

Cardiac Glycosides↗

PubMed2004

Comparison of spot tests with AdultaCheck 6 and Intect 7 urine test strips for detecting the presence of adulterants in urine specimens.

BACKGROUND: Several adulterants are used to mask tests for abused drugs in urine. Adulterants such as "Klear" and "Whizzies" contain potassium nitrite while "Urine Luck" contains pyridinium chlorochromate (PCC). The presence of these adulterants cannot be detected by routine specimen integrity check (pH, specific gravity, creatinine and temperature). We previously reported the development of rapid spot tests to detect the presence of these adulterants. AdultaCheck 6 and Intect 7 urine test strips are commercially available for detecting the presence of these adulterants along with specific gravity, creatinine and pH in urine. METHODS: The performance of these two test strips for detecting adulterants was compared with the results obtained by spot tests. RESULTS: Both AdultaCheck 6 and Intect 7 effectively detected the presence of nitrite and pyridinium chlorochromate in urine. Moreover, both test strips successfully detected the presence of glutaraldehyde, for which no spot test is currently available. High amount of glucose and ascorbic acid did not cause any false positive result with AdultaCheck 6 or Intect 7. CONCLUSIONS: Both AdultaCheck 6 and Intect 7 can be used for checking the integrity of a urine specimen submitted for drugs of abuse testing.

Ascorbic Acid↗

PubMed2004

Interference of carbamazepine and carbamazepine 10,11-epoxide in the fluorescence polarization immunoassay for tricyclic antidepressants: estimation of the true tricyclic antidepressant concentration in the presence of carbamazepine using a mathematical model.

We evaluated effects of carbamazepine and its metabolite, carbamazepine 10,11-epoxide, on the measurement of tricyclic antidepressant (TCA) concentrations in serum using the fluorescence polarization immunoassay (FPIA). We determined apparent TCA concentrations in 30 patients who were receiving carbamazepine but no TCAs. Carbamazepine concentrations ranged from 1.4 to 20.9 microg/mL (5.9-88.4 micromol/L); the observed apparent TCA concentrations ranged from 31.8 to 130.1 ng/mL (113.4-463.9 micromol/L). When aliquots of the drug-free serum pool were supplemented with known concentrations of carbamazepine or its metabolite, we observed significant apparent TCA concentrations using the FPIA; however, interference of carbamazepine was more than 3-fold more than its metabolite. When serum pools prepared from patients receiving TCA but no anticonvulsant medications were supplemented with known amounts of carbamazepine or its metabolite, we observed falsely elevated TCA concentrations. We formulated an equation to calculate the apparent TCA concentration from known carbamazepine concentrations. If carbamazepine and TCAs are present in a specimen, the true TCA concentration can be estimated by subtracting the calculated TCA concentration (due to carbamazepine) from the observed TCA concentration as measured by the TCA FPIA. This mathematical modeling is feasible because TCAs, even at very high concentrations, showed no interference with the carbamazepine FPIA.

Antidepressive Agents, Tricyclic↗

PubMed2003

Effect of the traditional Chinese medicines Chan Su, Lu-Shen-Wan, Dan Shen, and Asian ginseng on serum digoxin measurement by Tina-quant (Roche) and Synchron LX system (Beckman) digoxin immunoassays.

Chan Su, Lu-Shen-Wan, Dan Shen, and Asian ginseng are traditionally used to treat a number of conditions, including cardiovascular disease. All of these traditional Chinese medicines exhibit cardioactive properties. Digoxin is a cardioactive drug with a narrow therapeutic range (0.8-1.9 ng/mL). A patient taking digoxin may also take these Chinese medicines for their cardiotonic effects. Moreover, the active components of these medicines that are responsible for cardiotonic effects bear structural similarities to digoxin. Therefore, we studied the potential interference of these Chinese medicines with two digoxin immunoassays--the Tina-quant (Roche Diagnostics) and the Beckman (Synchron LX system)--and compared the values with the fluorescence polarization immunoassay (FPIA; Abbott Laboratories). When very small amounts (2-5 microL) of aqueous extract of Chan Su or Lu-Shen-Wan were added to drug-free serum, we observed high digoxin-like immunoreactivity with the FPIA. In contrast, when ethyl acetate extract of Dan Shen or microliter amounts of ginseng extract were added to drug-free serum, we observed modest digoxin-like immunoreactivity with the FPIA, but no apparent digoxin activity with the Roche and Beckman digoxin immunoassays. When aliquots of a digoxin pool prepared from patients receiving digoxin were supplemented with these Chinese medicines, we observed the most significant interference with the FPIA. The presence of endogenous digoxin-like immunoreactive substances can have additive effects with these Chinese medicines and falsely increase apparent digoxin levels by the FPIA. On the other hand, the Roche and Beckman assays were free from interference from DLIS but showed significant interference from Chan Su and Lu-Shen-Wan. We conclude that the FPIA showed the most significant interference from all four of the Chinese medicines we studied. However, the Roche and Beckman assays showed no interference from two (Dan Shen and Asian ginseng) of the four Chinese medicines we studied.

Bufanolides↗

PubMed2003

Impaired protein binding of Chinese medicine DanShen in uremic sera and sera with hyperbilirubinemia: rapid assessment of total and free DanShen concentrations using the fluorescence polarization immunoassay for digoxin.

DanShen is a Chinese medicine that is used to treat cardiovascular disorders. DanShen is moderately to strongly protein bound, mainly to albumin. Because impaired protein binding of albumin-bound drugs in uremia has been reported, we studied protein binding of DanShen by measuring the digoxin-like immunoreactive component of this Chinese medicine. We observed a significantly higher percentage of free fraction of DanShen in uremic sera in vitro. Impaired protein binding of DanShen was also observed in sera from patients with liver disease, who had elevated concentrations of bilirubin. Treating uremic sera with activated charcoal significantly improved the protein binding of DanShen, indicating that uremic compounds are responsible for the impaired protein binding of DanShen. On the other hand, when various amounts of bilirubin were added to aliquots of the normal pool supplemented with DanShen, we observed only a modest displacement of DanShen from the protein-binding sites by bilirubin, indicating that hypoalbuminemia may play a major role in impaired protein binding of DanShen in sera with elevated bilirubin concentrations. We conclude that protein binding of DanShen is lower in uremic sera and in sera with elevated bilirubin concentrations.

Acetates↗

PubMed2003

Activated charcoal is effective but equilibrium dialysis is ineffective in removing oleander leaf extract and oleandrin from human serum: monitoring the effect by measuring apparent digoxin concentration.

Accidental poisoning from oleander leaf or oleander tea can be life threatening. The authors studied the effectiveness of activated charcoal and equilibrium dialysis in removing oleander leaf extract and commercially available oleandrin as well as oleandrigenin, the active components of oleander plant, from human serum. Oleander leaf extract was prepared in distilled water and drug-free serum was supplemented with the extract. Then serum was treated with activated charcoal at room temperature and an aliquot was removed at 0 minutes, 10 minutes, 20 minutes, and finally 30 minutes to study the presence of oleander extract by measuring the apparent digoxin concentration using the FPIA for digoxin. The authors observed effective removal of oleander extract by activated charcoal. When the authors supplemented other drug-free serum pools with pure oleandrin or oleandrigenin and then subsequently treated them with activated charcoal, the authors observed complete removal of digoxin-like immunoreactivity at the end of 30 minutes' treatment. When drug-free serum pool supplemented with either oleander leaf extract, oleandrin, or oleandrigenin was passed through a small column packed with activated charcoal, the authors observed almost no apparent digoxin concentration following the passage through the column indicating that activated charcoal is very effective in removing oleander from human serum in vitro. In contrast, when serum pools containing either oleander leaf extract or oleandrin were subjected to equilibrium dialysis against phosphate buffer at pH 7.4, the authors observed no significant reduction in apparent digoxin concentration even after 24 hours. The authors conclude that activated charcoal is effective but equilibrium dialysis is ineffective in removing oleander leaf extract from human serum.

Cardenolides↗

PubMed2003

Use of fluorescence polarization immunoassay for salicylate to avoid positive/negative interference by bilirubin in the Trinder salicylate assay.

BACKGROUND: Significant positive bias of bilirubin in the Trinder salicylate method on automated analysers has been reported. Because the fluorescence polarization immunoassay (FPIA) for salicylate is also widely used in the clinical laboratory, we studied the potential interference of bilirubin in the salicylate FPIA. METHODS: Salicylate serum pools (three different pools) were prepared from patients receiving salicylate. We also prepared a normal serum pool containing no salicylate and serum pools containing no salicylate but elevated bilirubin. Aliquots of one salicylate pool were supplemented with various concentrations of bilirubin (42.8- 427.5 micro mol/L) and salicylate concentrations were measured by the salicylate FPIA (TDxFLx and AxSYM analysers). We also assayed these specimens with the Trinder salicylate method, using both Synchron LX and Hitachi 917 analysers for comparison with the results obtained by the FPIA method. In another experiment, aliquots of the two other salicylate pools were supplemented with various concentrations of bilirubin (42.8-684.0 micro mol/L) in order to further study the effect of very high bilirubin concentrations on the salicylate FPIA. We also added known amounts of salicylate to serum pools containing elevated bilirubin but no salicylate and measured salicylate using the FPIA in order to study the recovery of salicylate in the presence of elevated bilirubin concentrations. RESULTS: The FPIA showed minimal interference from bilirubin. We also observed good recovery of salicylate when specimens high in bilirubin but containing no salicylate were supplemented with known amounts of salicylate and the FPIA was used for the measurement of salicylate concentration. However, we observed falsely low salicylate concentrations with the Trinder method using the Synchron LX (primary wavelength 560 nm, secondary wavelength 700 nm) analyser and falsely increased salicylate concentrations using the same reagent but the Hitachi 917 (primary wavelength 546 nm, no secondary wavelength) analyser in the presence of elevated bilirubin levels compared with the FPIA results. CONCLUSION: We conclude that the FPIA for salicylate is not affected by high bilirubin concentrations up to 427.5 micro mol/L.

Artifacts↗

PubMed2003

Effect of Asian and Siberian ginseng on serum digoxin measurement by five digoxin immunoassays. Significant variation in digoxin-like immunoreactivity among commercial ginsengs.

Asian and Siberian ginsengs contain glycosides with structural similarities to digoxin. We studied potential interference of ginseng in 5 digoxin immunoassays in 3 Asian (2 liquid extracts, 1 capsule) and 3 Siberian ginseng preparations (1 liquid extract, 2 capsules). With the fluorescence polarization immunoassay (FPIA), we observed apparent digoxin activity in 1 Asian liquid preparation and in the liquid extract and 1 capsule form of Siberian ginseng. In mice fed ginseng, we observed digoxin activities in the serum (Asian, 0.48-0.68 ng/mL [0.6-0.9 nmol/L]; Siberian, 0.20-0.47 ng/mL [0.3-0.6 nmol/L]), indicating that such interferences also occur in vivo. Serum pools prepared from samples from patients receiving digoxin and then supplemented with Asian or Siberian ginseng showed falsely increased digoxin values using the FPIA (e.g., for Asian ginseng, 1.54 ng/mL [2.0 nmol/L] vs control value, 1.10 ng/mL [1.4 nmol/L]) and falsely decreased values using the microparticle enzyme immunoassay (MEIA; 0.73 ng/mL [0.9 nmol/L] vs control value, 1.04 ng/mL [1.3 nmol/L]). Digoxin-like immunoreactive substances (DLISs) showed synergistic effects with ginsengs in interfering with the FPIA and MEIA for digoxin. No interference was observed with 3 other digoxin assays, even in the presence of elevated DLISs.

Animals↗

PubMed2002

Bidirectional (positive/negative) interference of spironolactone, canrenone, and potassium canrenoate on serum digoxin measurement: elimination of interference by measuring free digoxin or using a chemiluminescent assay for digoxin.

Spironolactone and potassium canrenoate (aldosterone antagonist diuretics) are often used with digoxin in clinical practice. Spironolactone, potassium canrenoate, and their common metabolite canrenone cross-react with the fluorescence polarization immunoassay (FPIA) for digoxin, and can falsely elevate serum digoxin concentrations. Serum digoxin concentrations were falsely lowered when the microparticle enzyme immunoassay (MEIA) was used. Aliquots of drug-free serum were supplemented with therapeutic and above-therapeutic concentrations of spironolactone, canrenone, and potassium canrenoate, and apparent digoxin activities were measured. We observed digoxin-like activities in the FPIA, but observed no activity with the MEIA or the chemiluminescent assay (CLIA). However, when serum digoxin pools prepared from patients receiving digoxin were supplemented with these compounds, we observed suppression of total digoxin levels with the MEIA. In contrast, no interference was observed in the presence of these compounds when CLIA was used for digoxin measurement. These compounds are strongly protein-bound, and no apparent digoxin activity was observed in the protein-free ultrafiltrate when drug-free sera were spiked with high levels of these compounds. Taking advantage of strong protein binding of these compounds and weak protein binding of digoxin (25%), interference of spironolactone, canrenone, and potassium canrenoate in FPIA and MEIA digoxin assays can be mostly eliminated by monitoring free digoxin concentration. Another approach to avoid this interference is to use the CLIA digoxin assay.

Canrenoic Acid↗

PubMed2002

Drug-herb interactions: unexpected suppression of free Danshen concentrations by salicylate.

The general population of the U.S. uses over-the-counter herbal medicines. Danshen is a Chinese herbal product used for the treatment of cardiovascular disease. In a previous study we showed that Danshen has significant digoxin-like immunoreactivity, and we used this parameter to monitor total and free Danshen activities in sera (10). In this report we demonstrated strong protein binding of Danshen (50-70%), and we also identified albumin as the major serum protein that binds Danshen. Because salicylate, which is also strongly bound to albumin, is a widely used over-the-counter medicine in the U.S., we studied Danshen-salicylate interaction in vitro. We observed no significant change in free Danshen concentrations as measured by free-digoxin-like activity when salicylate concentrations were subtherapeutic (< or = 100 microg/mL). With therapeutic concentrations of salicylate (> or = 150 microg/mL), the free Danshen concentrations significantly decreased from the control. On the other hand, Danshen can displace salicylate from protein binding, thereby increasing the free salicylate concentration. We conclude that salicylate in therapeutic concentration can significantly decrease free Danshen concentrations, and Danshen can displace salicylate.

Albumins↗

PubMed2002

In vivo digoxin-like immunoreactivity in mice and interference of Chinese medicine Danshen in serum digoxin measurement: elimination of interference by using a chemiluminescent assay.

BACKGROUND: Danshen, a traditional Chinese medicine used in the management of cardiovascular diseases, is available without prescription in the US. Because Danshen is used to treat cardiovascular diseases, we studied the potential interference of Danshen with serum digoxin measurement using various immunoassays. METHODS: Blood was collected 1 day before and then 1 and 2 h after feeding mice with Danshen. The apparent digitoxin activities were measured by the fluorescence polarization immunoassay (FPIA). We also added microliter amounts of Danshen extract to digoxin pools prepared from patients receiving digoxin. The digoxin concentrations were measured using the fluorescence polarization immunoassay (FPIA), microparticle enzyme immunoassay (MEIA) and chemiluminescent assay (CLIA). The observed values were compared with original values. We also fed mice with Danshen. RESULTS: We observed measurable digoxin-like immunoreactivity in sera of mice after feeding with Danshen. We also observed falsely lower digoxin concentrations (negative interference) when MEIA was used for digoxin measurement. However, serum digoxin concentrations were falsely elevated with FPIA. We observed no interference of Danshen in serum digoxin measurement using the CLIA. CONCLUSION: Danshen appears to contain digoxin-like immunoreactivity but does not interfere with serum digoxin measurement when CLIA was used.

Animals↗

PubMed2002

Activated charcoal is more effective than equilibrium dialysis in removing Chinese medicines Chan Su and Dan Shen from serum and activated charcoal also prevents further absorption of these agents from G.I. tract in mice: monitoring the effect in clinical laboratory by measuring digoxin activity in serum.

BACKGROUND: Chinese medicines are freely available without prescription and are widely used by the general population. Chan Su and Dan Shen are both indicated for the treatment of cardiac diseases. Severe toxicity from Chan Su has been reported. We studied the possibility of removing Chan Su and Dan Shen from human sera using activated charcoal and equilibrium dialysis, and also examined the potential benefit of preventing absorption of these agents from the G.I. tract in the mouse model. METHODS: For in vitro studies, drug-free serum pools were supplemented with Chan Su or Dan Shen and then either treated with activated charcoal (10 and 25 mg/ml), or passed through a column packed with activated charcoal. Serum pools supplemented with Chan Su or Dan Shen were also subjected to equilibrium dialysis against phosphate buffer (pH 7.4) using dialysis membrane with molecular cut-off of 25,000 Da. Removal of Chan Su or Dan Shen from the serum was monitored by measuring the apparent digoxin concentration using the fluorescence polarization immunoassay (FPIA) for digoxin (Abbott Laboratories). RESULTS: We observed the fast and effective removal of both Chan Su and Dan Shen from the serum by activated charcoal. We also observed significant removal of both Chan Su and Dan Shen when the serum pools containing these Chinese medicines were passed through columns packed with activated charcoal. Although equilibrium dialysis was also effective in removing these Chinese medicines from the serum, 24 h was required for complete removal of Dan Shen activity, and for Chan Su, complete removal was not achieved even after 24 h. In our in vivo model, we observed significantly less digoxin activity in the group of mice that received activated charcoal compared to the control group. CONCLUSIONS: Activated charcoal is effective in preventing absorption of these Chinese medicines from the G.I. tract and can also remove these agents from the serum.

Animals↗

PubMed2002

Rapid spot tests for detecting the presence of adulterants in urine specimens submitted for drug testing.

Several adulterants are used to mask tests for abused drugs in urine. Adulterants such as "Klear" and "Whizzies" contain potassium nitrite, and "Urine Luck" contains pyridinium chlorochromate (PCC). The presence of these adulterants cannot be detected by routine specimen integrity checks (pH, specific gravity, and temperature). We developed rapid spot tests for detecting these adulterants in urine. Addition of 3% hydrogen peroxide in urine adulterated with PCC caused rapid formation of a dark brown color. In contrast, unadulterated urine turned colorless when hydrogen peroxide was added. When urine contaminated with nitrite and 2 to 3 drops of 2N hydrochloric acid were added to 2% aqueous potassium permanganate solution, the dark pink permanganate solution turned colorless immediately with effervescence. Urine contaminated with nitrite liberated iodine from potassium iodide solution in the presence of 2N hydrochloric acid. Urine adulterated with PCC also liberated iodine from potassium iodide in acid medium but did not turn potassium permanganate solution colorless. Urine specimens from volunteers and random urine samples that tested negative for drugs did not cause false-positive results. These rapid spot tests are useful for detecting adulterated urine to avoid false-negative drug tests.

False Negative Reactions↗

PubMedDate not supplied

Mycobacterial glycolipid cord factor trehalose 6,6'-dimycolate causes a decrease in serum cortisol during the granulomatous response.

Serum cortisol levels were evaluated in mice following intravenous administration of purified mycobacterial glycolipid trehalose 6,6'-dimycolate (TDM). C57BL/6 mice develop lung granulomas in response to TDM, while A/J mice are deficient in this process. Administration of TDM to C57BL/6 mice led to a rapid reduction in serum cortisol, concurrent with initiation of the granulomatous response and cytokine and chemokine mRNA induction. Cortisol levels were lowest on day 5 after TDM administration, but there was significant production of IL-6, TNF-alpha and IL-1beta messages. Granuloma formation and full immune responsiveness to TDM were only apparent upon a sufficient decrease in levels of systemic cortisol. Treatment of the C57BL/6 mice with hydrocortisone abolished inflammatory responses. Histologically nonresponding A/J mice exhibited higher constitutive serum cortisol and demonstrated different kinetics of cortisol reduction upon administration of TDM. A/J mice demonstrated hyperplastic morphology in the suprarenal gland with a high degree of vacuolization in the medullary region and activation of cells in the zona fasciculata and zona reticularis. The A/J mice were dysregulated with respect to cytokine responses thought to be necessary during granuloma formation. The high constitutive serum cortisol in the A/J mice may therefore contribute to pulmonary immunoresponsiveness and the establishment of an environment counterproductive to the initiation of granulomatous responses. The identification of a mycobacterial glycolipid able to influence serum cortisol levels is unique and is discussed in relation to immunopathology during tuberculosis disease.

Adrenal Cortex↗