Selective adsorption of antibiotics from human urine using biochar modified by dimethyl sulfoxide, deep eutectic solvent, and ionic liquid.

Antibiotics present in human urine pose significant challenges for the use of urine-based fertilizers in agriculture. This study introduces a novel two-stage approach utilizing distinct biochar types to mitigate this concern. Initially, a modified biochar selectively adsorbed azithromycin (AZ), ciprofloxacin (CPX), sulfamethoxazole (SMX), trimethoprim (TMP), and tetracycline (TC) from human urine. Subsequently, a separate pristine biochar was employed to capture nutrients. Biochar, derived from sewage sludge and pyrolyzed at 550 and 700 °C, was modified using dimethyl sulfoxide, deep eutectic solvent, and ionic liquid to enhance antibiotic removal in the first stage. The modifications introduced hydrophilic functional groups (-OH/-COOH), which favor antibiotic adsorption. Adsorption kinetics followed the pseudo-second-order model, with the Langmuir isotherm model best describing the adsorption data. The maximum adsorption capacities for AZ, CPX, SMX, TMP, and TC after the modification were 196.08, 263.16, 81.30, 370.37, and 833.33 µg/g, respectively. Pristine biochar exhibited a superior ammonia adsorption capacity compared to the modified biochar. Hydrogen bonding, electrostatic attraction, and chemisorption drove antibiotic adsorption on the modified biochar. Regeneration efficiency declined due to solvent accumulation and potential byproduct formation on the biochar surface (<30% removal capacity after three cycles). This study presents innovative biochar modification strategies for selective antibiotic adsorption, laying the groundwork for environmentally friendly urine-based fertilizers in agriculture.

Automated annotation and quantification of metabolites in 1H NMR data of biological origin.

In (1)H NMR metabolomic datasets, there are often over a thousand peaks per spectrum, many of which change position drastically between samples. Automatic alignment, annotation, and quantification of all the metabolites of interest in such datasets have not been feasible. In this work we propose a fully automated annotation and quantification procedure which requires annotation of metabolites only in a single spectrum. The reference database built from that single spectrum can be used for any number of (1)H NMR datasets with a similar matrix. The procedure is based on the generalized fuzzy Hough transform (GFHT) for alignment and on Principal-components analysis (PCA) for peak selection and quantification. We show that we can establish quantities of 21 metabolites in several (1)H NMR datasets and that the procedure is extendable to include any number of metabolites that can be identified in a single spectrum. The procedure speeds up the quantification of previously known metabolites and also returns a table containing the intensities and locations of all the peaks that were found and aligned but not assigned to a known metabolite. This enables both biopattern analysis of known metabolites and data mining for new potential biomarkers among the unknowns.

New carbon dots based on glycerol and urea and its application in the determination of tetracycline in urine samples.

The current study proposes a fast one-pot microwave assisted synthesis of new carbon dots (CDs) based on glycerol and urea. The novel carbon nanoparticles (GUCDs) have been appropriately characterized and exhibited good luminescent properties with a quantum yield of about 9.8%. Interestingly, the GUCDs are able to selectively interact with tetracycline class antibiotics, which produce a decrease in the native fluorescence of the CDs. On the base of these features, a new analytical method has been developed for the determination of tetracycline. The proposed method has shown satisfactory analytical parameters, such as good linearity range -between 0.5 and 25 µM (R2 = 0.9997)- and an acceptable detection limit (165 nM). Moreover, the new method has been successfully applied for tetracycline determination in urine samples with good recoveries (94.7-103%) and precision (4.6 RSD%).

Development, validation and application of a novel HPLC-MS/MS method for the measurement of minocycline in human plasma and urine.

New treatments are urgently required to treat infections caused by multi-drug resistant Acinetobacter baumanni,. To address this need, a new formulation of Minocin®, (minocycline for injection) has been developed that allows for higher doses of minocycline to be administered. Phase 1 clinical trials were conducted in healthy volunteers to assess the safety and pharmacokinetics (PK) of this new formulation at higher doses. In order to generate PK data, novel, selective and simple HPLC-MS/MS based assays were developed and validated for the determination of minocycline (MC) in human plasma and urine. The respective working ranges were 0.05 to 30 mg/L and 0.1 to 30 mg/L. Removal of endogenous proteins with trichloroacetic acid was used as a simple means of extracting MC from the samples. An analogue, tetracycline was used as the internal standard (IS). Chromatographic separation, including that of MC from its 4-epimer (4-EMC), was achieved on a Waters XBridge BEH C18 column (50 x 4.6 mm ID, 5 µm) with gradient elution. The mobile phases comprised water containing 5 mM ammonium formate at a pH of 2.5, and methanol containing 5 mM ammonium formate. The internal standard (IS) was tetracycline, a structural analogue of minocycline. The methods were fully validated and met regulatory acceptance criteria for intra-run and inter-run accuracy and precision, carryover, dilution integrity and matrix effects. Mean extraction recoveries ranged between 64.3% and 84.6% for MC and 64.3% for the IS. There was no significant ion suppression or enhancement for MC or the IS. The validated assays were successfully applied to 1423 plasma and 689 urine samples from a Phase 1 clinical study. There was no evidence of instability, or significant interconversion between MC and 4-EMC, in stored clinical samples, spiked plasma and urine samples, or their extracts, under various test conditions.

An automated salting-out assisted liquid-liquid microextraction approach using 1-octylamine: On-line separation of tetracycline in urine samples followed by HPLC-UV determination.

An automated salting-out assisted liquid-liquid microextraction (SALLME) procedure based on a flow system was developed as new approach for pretreatment of complex sample matrix. In this procedure 1-octylamine was investigated as novel extractant for the SALLME. The procedure involved aspiration of the 1-octylamine and sample solution into a mixing chamber of a flow system followed by their air-bubble mixing resulting to isotropic solution formation. To provide phase separation a salting-out agent solution was added into the mixing chamber. After phase separation, the micellar 1-octylamine phase containing analyte was mixed with methanol and transported to a HPLC-UV system. To demonstrate the efficiency of the suggested approach, the automated procedure was applied for the HPLC-UV determination of tetracycline as a proof-of-concept analyte in human urine samples. Under the optimal conditions, the detector response of the analytes was linear in the concentration ranges of 0.5-20 mg L-1. The limit of detection, calculated from a blank test based on 3σ, was 0.17 mg L-1. The results demonstrate that the developed approach is highly cost-effective, simple and rapid.

Collision cross section (CCS) as a complementary parameter to characterize human and veterinary drugs.

In the context of human and veterinary drugs identification, ion mobility spectrometry (IMS) in combination with mass spectrometry (MS) may provide a relevant complementary piece of information to mass-to-charge ratio (m/z), the so-called collision-cross-section (CCS). Up to now, however, the application of CCS as identification parameter has not been fully investigated due to the reduced number of these drugs that have being characterized in terms of CCS. This work proposes a CCS database for 92 human and veterinary drugs, including eighteen benzimidazoles, eleven 5-nitroimidazoles, eleven aminoglycosides, nineteen quinolones, eighteen ß-lactams, ten sulfonamides and five tetracyclines. Among them, 37 drugs have been characterized in terms of CCS for the first time. The CCS values of the other 55 compounds have been compared with those from a recently published database in order to evaluate inter-laboratory reproducibility, which is crucial for the implementation of the CCS as identification parameter. CCS values were measured by traveling wave ion mobility spectrometry (TWIMS) under positive ionization conditions. Nitrogen was used as drift gas in the ion mobility cell. The proposed database covers 173 ions including [M+H]+ and [M+Na]+ species. High correlation between m/z and CCS has been observed for [M+H]+ (R2 = 0.9518, n = 91) and [M+Na]+ (R2 = 0.9135, n = 82) ions. As expected, CCS values for sodium adducts are generally greater than for protonated molecules because they exhibit higher molecular weight. However, sodium adducts of aminoglycosides, ß-lactams, and of several quinolones and benzimidazoles, were characterized as more compact ions than their related protonated molecule. In addition, this work describes the fragmentation pattern observed for the studied molecules. For the first time, the main fragment ions for most of the compounds have also been characterized in terms of CCS, involving a total of 238 ions. As proof of concept, for the application of this database to biological matrices, eleven veterinary drugs in bovine urine samples were characterized in terms of CCS, showing that this parameter was not influenced by the matrix.

Carbon dots derived from rose flowers for tetracycline sensing.

Herein, an innovative and simple method for synthesizing carbon dots (CDs) with satisfactory fluorescence has been successfully established while rose flowers served as carbon source for the first time. Meanwhile, the fluorescence (FL) mechanism of current CDs was elucidated in detail by fluorescence, UV-vis, HR-TEM, and FTIR-based analyses. Subsequently, this type of CDs was employed for detecting tetracycline (TC) on the basis of the interactions between TC and CDs, and allowed quenching their fluorescence. Moreover, the proposed analytical strategy permitted detecting TC in a linear range of 1.0×10(-8)-1.0×10(-4) mol/L with a detection limit of 3.3×10(-9) mol/L at a signal-to-noise ratio of 3. Significantly, the CDs described here were further applied for fluorescent coding, demonstrating their promising future towards various applications in analytic science.

Tumor necrosis factor alpha and interleukin-1 stimulate bone resorption in vivo as measured by urinary [3H]tetracycline excretion from prelabeled mice.

Tumor necrosis factor alpha (TNF-alpha) and interleukin-1 (IL-1) have been shown to stimulate bone resorption in vitro. We have now investigated whether these cytokines also cause a similar action when administered in vivo. This was made possible by the adaptation of a newly developed technique that enables the continual assessment of bone resorption in vivo in mice by measuring urinary excretion of 3H from [3H]tetracycline-prelabeled animals. Experiments using maneuvers known to influence bone resorption, such as a change in dietary calcium or administration of parathyroid hormone or dichloromethylenebisphosphonate, indicate that the technique is reliable and sensitive in mice. Daily intravenous administration of either recombinant human or recombinant murine TNF-alpha, as well as subcutaneous administration of recombinant human IL-1 alpha, were found to stimulate bone resorption in a dose-dependent manner. The effect was maximal within 2 days. Thus, exogenous TNF-alpha and IL-1 alpha can stimulate bone resorption in vivo, suggesting that these cytokines may also exert a systemic effect on bone.

Evaluation of urinary pyridinium crosslink excretion as a marker of bone resorption in the rat.

The aim of this study was to evaluate the value of the urinary excretion of the pyridinium crosslinks, pyridinoline (Pyr) and deoxypyridinoline (D-Pyr), as markers of bone resorption in the rat. The excretion of the crosslinks was compared with that of urinary [3H]tetracycline ([3H]TC) excretion from chronically [3H]TC-prelabeled animals, a technique established to monitor bone resorption in the rat. Bone resorption was modulated by Ca restriction, infusion of PTH, thyroparathyroidectomy, and administration of different bisphosphonates. Furthermore, the urinary crosslinks were assessed in three different osteopetrotic mutations in the rat. We found a delayed response of Pyr and D-Pyr excretion to acute changes in bone resorption compared with [3H]TC excretion. This delay was 1 day after Ca restriction and longer after other treatments, such as PTH administration or bisphosphonate treatment, with which it was more than 3 weeks. In contrast, chronic states with stimulation or inhibition of bone resorption showed similar changes in excretion of the urinary crosslinks and [3H]TC, except after PTH administration. The excretion of the crosslinks was greatly reduced in osteopetrotic rats (op/op, tl/tl, and ia/ia) and increased to normal levels in tl/tl rats after stimulation of bone resorption by M-CSF administration. These results suggest that, in rats, urinary excretion of the pyridinium crosslinks reflects bone resorption in chronic but not always in acute conditions. The cause of this discrepancy is still unclear.

BM 21.0955, a potent new bisphosphonate to inhibit bone resorption.

A total of 300 new bisphosphonates were screened for their effect on bone resorption in the rat. Among these, 1-hydroxy-3-(methylpentylamino)propylidenebisphosphonate (BM 21.0955) was selected for detailed investigation. It inhibited arotinoid-stimulated bone resorption as assessed by calcemia in thyroparathyroidectomized rats at a SC dose as low as 0.001 mg P (0.016 mumol) per kg body weight per day. The compound was thus about 2, 10, 50, and 500 times more potent than risedronate, alendronate, pamidronate, and clodronate, respectively. Intravenous administration was as effective as subcutaneous, and oral administration was 100 times less effective. The effect after one administration decreased with time but was still measurable after 2 weeks. Nonstimulated bone resorption assayed by the urinary excretion of radiolabeled tetracycline from lifelong prelabeled animals was also inhibited. This effect started 3 days after a single dose and was still maximal after 7 days. Histomorphometric analysis of the tibial metaphysis in growing intact rats also showed an inhibition of bone resorption along with an increase in bone mass. The number of osteoclasts increased in animals treated with 0.01 and 0.1 mg P per kg (0.16 and 1.6 mumol/kg) body weight SC but decreased in animals given 1 mg P per kg (16.1 mumol/kg), showing that the inhibition of bone resorption was not due to an inhibition of osteoclast recruitment. No inhibition of mineralization occurred. This new bisphosphonate appears to have great potential for use in human bone disease.

Effect of cimetidine and antacids on gastrointestinal absorption of tetracycline.

In a randomized crossover study, five normal subjects were given 250-mg capsules of tetracycline at weekly intervals with cimetidine 300 mg. sodium bicarbonate 2 gm in water, magnesium-aluminum hydroxide gel 30 ml, or water alone. Gastric pH was monitored by radiotelemetry. Antibiotic bioavailability as measured by area under the serum level-time curve, peak serum level, and urinary elimination was not affected by cimetidine or sodium bicarbonate. Magnesium-aluminum hydroxide gel reduced bioavailability by 90%. The data show that gastric pH does not affect absorption of oral tetracycline and that cimetidine can be used in place of antacids to control gastric acid in patients using tetracycline.

The food-induced stimulation of bone resorption in the rat, assessed by the urinary [3H]-tetracycline excretion, is mediated by parathyroid hormone.

Using the urinary excretion of [3H]-tetracycline from prelabeled rats to monitor bone resorption, we have previously shown that food intake is associated with a rapid and large increase in bone resorption. This increase is blunted when the daily intake is fractionated into 4 portions instead of being given at once. Food fractionation also leads to a large increase in bone mass. In order to establish whether the thyroparathyroid gland is involved in this effect, thyroparathyroidectomized (TPTX) rats were studied. The food-induced increase in bone resorption was absent in TPTX rats. Therefore, the pattern of parathyroid hormone (PTH) was investigated during the development of the food-induced bone resorption, and under food fractionation. Rats were trained to eat their daily high Ca food in less than two hours. Thereafter they were given food portions of 5 or 20 grams, respectively. PTH in serum was measured at 0, 1, 2, 3, and 4 hours after food intake. In rats given the large food portions, a conspicuous increase of PTH was found. In contrast, serum PTH of rats fed the small food portion did only change to an insignificant extent. This study in rats shows that the ingestion of a large meal induces a transient increase of PTH. The present results can therefore explain the formerly observed acute increase in bone resorption following food intake and its blunting by food fractionation. It is not known, whether such a mechanism occurs also in humans. If so, these results would provide the rational basis to decrease bone resorption by food fractionation.

Interaction of cations and chelators with the intestinal absorption of tetracycline.

The influence of certain compounds on intestinal absorption of tetracycline was tested, using two different in vivo techniques: a) Disappearence of the drug from perfused intestinal segments of the rabbit; b) Measuring urinary excretion in the rat after oral dosage. Ca2+ and Fe2+ ions both reduced the permeation rate of tetracycline by about 30%. In presence of Ca2+ and salicylate ions, leading to ion-pair formation with the antibiotic, intestinal uptake was significantly increased in comparison to experiments where only calcium was present. A more pronounced increase was observed with EDTA. Phosphate ions had different effects on the uptake of the antibiotic in both experimental techniques. Possible mechanisms are discussed.

High-pressure liquid chromatographic determination of tetracyclines in urine.

The quantitation of oxytetracycline, tetracycline, and chlortetracycline was accomplished by high-pressure liquid chromatography using an anion-exchange column. The tetracyclines were extracted from urine as their calcium complexes. Concentrations as low as 12 microgram of oxytetracycline/ml and 4 microgram of tetracycline and chlortetracycline/ml were quantitated accurately. The relative standard deviation of the method varied from 0 to 5%.

Renal excretion of tetracycline is transiently decreased during short-term heat exposure.

Renal blood flow is known to be reduced during intensive external heating, which may have clinical relevance for renal drug elimination as well. The effects of heat exposure in a sauna bath on tetracycline pharmacokinetics were studied in 8 healthy volunteers in an open, randomized crossover study. The subjects were given a single oral dose of tetracycline (500 mg) both in a control session and in a sauna bathing session. The heat exposure consisted of three 10-minute stays in a sauna bath (temperature 76-87 degrees C, relative humidity 27-33%) starting 20 minutes after drug administration. The stays in the steam room were separated by two 5-minute cooling periods at 23 degrees C. Venous blood samples for determination of plasma tetracycline concentrations were taken 15 min before the drug intake, 20, 40, 60 min, and 2, 3, 4, 6, 8, and 24 h after it. The control session at room temperature (23 degrees C) followed the same sampling protocol. No statistically significant differences in tetracycline plasma concentrations, Cmax, Tmax, or AUC0-24h were seen. In addition, urine was collected (0-2 h, 2-5 h, 5-8 h, and 8-24 h) for determination of the amount of tetracycline excreted unchanged. Urinary tetracycline excretion was transiently (2-5 h after drug intake) reduced in the sauna session (P < 0.05 vs. control, Wilcoxon). The other collection periods and the total urinary excretion of tetracycline (24 h) did not differ from the control session. It is concluded that urinary tetracycline excretion was transiently decreased during short-term heat exposure, but otherwise the effects of external heating on tetracycline pharmacokinetics were negligible.

Urine concentrations of chloramphenicol, tetracycline, and sulfisoxazole after oral administration to healthy adult dogs.

Chloramphenicol, tetracycline, and sulfisoxazole were administered (orally) in separate trials to clinically healthy adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and an aliquot from each period was assayed for antimicrobial activity. Daily doses of the antimicrobics were as follows: chloramphenicol 99 mg/kg of body weight, tetracycline 55 mg/kg, and sulfisoxazole 66 mg/kg. Mean 8-hour urine concentrations (+/- 1SD) for chloramphenicol were 124 +/- 40 micrograms/ml; for tetracycline, 138 +/- 65 micrograms/ml; and for sulfisoxazole, 1,466 +/- 832 micrograms/ml. The mean 8-hour percentages of the doses of drug eliminated in active form in the urine were 6.3 +/- 2.6% for chloramphenicol, 11.2 +/- 2.0% for tetracycline, and 68.5 +/- 2.1% for sulfisoxazole.

Etiopathogenesis of uncommon canine uroliths. Xanthine, carbonate, drugs, and drug metabolites.

Metabolic disorders, medication, and diagnostic agents may be associated with urolithiasis in dogs. Examples of uroliths that have been uncommonly encountered in dogs include xanthine, dolomite, tetracycline, and sulfonamides. Detection of these and other apparently uncommon uroliths requires a high index of suspicion and proper methods of analysis.

Effect of magnesium trisilicate and citric acid on the biovailability of tetracycline in man.

Oral absorption of tetracycline hydrochloride by human subjects was compared with its absorption when coadministered with magnesium trisilicate, citric acid or magnesium trisilicate-citric acid mixture. Evaluation of the absorption rate was done by means of urinary excretion measurements. The concomitant administration of magnesium trisilicate with tetracycline hydrochloride resulted in a dramatic reduction of the excretion rate of the drug. Ingestion of citric acid with tetracycline showed no significant effect on its absorption. Citric acid administration simultaneously with tetracycline hydrocloride-magnesium trisilicate combination failed to improve the absorption of tetracycline in the presence of magnesium trisilicate contrarily to preveious in vitro results. Conclusions were made that in vitro experiments are not always successful in the prediction of in vivo findings.

Novel and remarkable enhanced-fluorescence system based on gold nanoclusters for detection of tetracycline.

Tetracycline and Eu(3+), while coexisting, usually appear as a complex by chelating. This complex shows low fluorescence intensity, leading to its limitation of analytical goals. Gold nanoclusters (AuNCs), emerging as novel nano-material, are attracting increasing attentions in multiple fields. Herein, gold nanoclusters first function as a fluorescence-enhanced reagent rather than a conventional fluorescent-probe, and a dramatic enhanced-fluorescence system was built based on Eu(3+)-Tetracycline complex (EuTC) by introducing gold nanoclusters. Simultaneously, three types of gold nanoclusters were employed for exploring various conditions likely affecting the system, which demonstrate that no other gold nanoclusters than DNA-templated gold nanoclusters enormously caused fluorescence-enhancement of EuTC. Moreover, this enhanced-fluorescence system permitted available detection of tetracycline (TC) in a linear range of 0.01-5 µM, with a detection limit of 4 nM at a signal-to-noise ratio of 3. Significantly, the practicality of this method for detection of TC in human urine and milk samples was validated, demonstrating its advantages of simplicity, sensitivity and low cost. Interestingly, this system described here is probably promising for kinds of applications based on its dramatically enhanced-fluorescence.

Aptamer based extraction followed by electrospray ionization-ion mobility spectrometry for analysis of tetracycline in biological fluids.

An extraction method based on aptamer sorbent followed by electrospray ionization-ion mobility spectrometry (ESI-IMS) has been developed for the analysis of tetracycline in human urine and plasma samples. The effect of extraction parameters on the extraction efficiency including washing (solvent type and volume) and elution (solvent type, volume and flow rate) were investigated. Under the optimized conditions, the linear dynamic ranges for tetracycline in urine and plasma samples were found to be 0.05-5.00 µg/mL and 0.10-5.00 µg/mL with detection limits of 0.019 and 0.037 µg/mL, respectively. The extraction efficiency was 86.5% for urine and it was 82.8% for plasma samples. The relative standard deviation was 5.9% and 6.3% for six replicate measurements of tetracycline at 1 and 2 µg/mL in urine and plasma samples, respectively.