Phytochemical and ethnomedicinal evidences of the use of Alternanthera brasiliana (L.) Kuntze against infectious diseases.

ETHNOPHARMACOLOGICAL RELEVANCE: Popularly known as "penicilina" and "terramicina", Alternanthera brasiliana (L.) Kuntze belongs to the Amaranthaceae family and stands out for its ethnomedicinal uses in the treatment of infections caused by pathogenic microorganisms in some countries. AIM OF THE STUDY: The present study aimed to carry out a literature review and analyze whether the scientific evidence really validates the numerous indications for the use of A. brasiliana in traditional medicine for the treatment of infectious diseases. Phytochemical and toxicological studies related to this species were also analyzed. MATERIAL AND METHODS: Scientific documents were retrieved from Google Scholar, PubMed®, ScienceDirect®, SciELO, SpringerLink®, Scopus®, and Web of Science™ databases. The literature was reviewed from the first report on the antimicrobial activity of A. brasiliana in 1994 until April 2024. RESULTS: According to the scientific documents analyzed, it was observed that A. brasiliana is widely used as a natural antibiotic for the treatment of infectious diseases in Brazil, mainly in the states of Rio Grande do Sul, Mato Grosso, and Minas Gerais. Its ethnomedicinal uses have also been reported in other countries such as Colombia and India. The leaves (78%) of A. brasiliana are the main parts used in the preparation of herbal medicines by traditional communities. Several A. brasiliana extracts showed low activity when evaluated against pathogens, including gram-positive bacteria, gram-negative bacteria, parasitic protozoa, and fungi. Only two studies reported that extracts from this plant showed high activity against the herpes simplex virus, Mycobacterium smegmatis, and Candida albicans. Phytochemicals belonging to the classes of phenolic compounds and flavonoid (52%), saturated and unsaturated fatty acids (33%), steroids and phytosterols (8%), terpenoids (5%), and fatty alcohol esters (2%) were identified in A. brasiliana. Toxicity (in vivo) and cytotoxicity (in vitro) studies of polar and non-polar extracts obtained from A. brasiliana leaves indicated that this plant is biologically safe. CONCLUSION: Despite being widely used as a natural antibiotic by traditional communities, scientific investigations related to the antimicrobial potential of A. brasiliana extracts have indicated inactivity against several pathogens.

Working Memory and Manual Dexterity in Dyslexic Children: A Systematic Review and Meta-Analysis.

Dyslexic children have impairments in working memory and manual dexterity. Studies have shown that when cognitive development has deficits, motor development is often impaired, indicating a strong interconnection between both domains, and the possibility of interference with each other's proper functioning. Thus, a new literature review is necessary to understand which components of working memory and manual dexterity are affected in dyslexic children and the possible relationship between them. This review aimed to perform a systematic review and meta-analysis to analyze both skills in dyslexic children. The protocol was carried out according to the criteria established by PRISMA being registered at PROSPERO under number CRD 42021238901. Six literature databases were searched to locate studies published between 2001 and 2021: EMBASE, ERIC, ISI Web of Science, PubMed, PsycINFO, and Scopus. 21 studies met the inclusion criteria. The findings suggest that dyslexic children have significantly poorer visuospatial and verbal working memory with more impairments in the phonological loop. No significant differences were found in manual dexterity.

Right Ventricular Septal Versus Apical Pacing: Long-Term Incidence of Heart Failure and Survival.

The clinical benefits of right ventricular septal (RVS) pacing compared to those of right ventricular apical (RVA) pacing are still in debate. We aimed to compare the incidence of heart failure (HF) and all-cause mortality in patients submitted to RVS and RVA pacing during a longer follow-up. This a single-center, retrospective study analysis of consecutive patients submitted to pacemaker implantation. The primary outcome was defined as the occurrence of HF during follow-up. The secondary outcome was all-cause death. A total of 251 patients were included, 47 (18.7%) with RVS pacing. RVS pacing was associated to younger age, male gender, lower body mass index, ischemic heart disease, and atrial fibrillation. During a follow-up period of 5.2 years, the primary outcome occurred in 89 (37.1%) patients. RVS pacing was independently associated with a 3-fold lower risk of HF, after adjustment. The secondary outcome occurred in 83 (34.2%) patients, and pacemaker lead position was not a predictor. Fluoroscopy time and rate of complications (rarely life-threatening) were similar in both groups. Our study points to a potential clinical benefit of RVS positioning, with a 3.3-fold lower risk of HF, without accompanying increase in procedure complexity nor complication rate.

Anticancer potential and toxicity of the genus Handroanthus Mattos (Bignoniaceae): A systematic review.

The genus Handroanthus Mattos (Bignoniaceae) is widely used for the treatment of cancer in traditional medicine in Brazil and other South American countries. The anticancer potential of species of this genus has been reported in the literature, indicating that their chemical compounds may be effective against different tumor cell lines. In this perspective, the present study aimed to conduct a systematic review of ethnobotanical, pharmacological, phytochemical and toxicological information on Handroanthus species related to cancer treatment. Searches were conducted in the Google Scholar, PubMed®, ScienceDirect® and SciELO databases. A total of 78 articles published in the last thirty-two years (1990-2022) were eligible and included in the review. According to the scientific documents analyzed, five species of Handroanthus are widely used for the treatment of cancer in the traditional medicine of Brazil and other South American countries, including Bolivia and Argentina. The bark (88%) is the main part used in traditional preparations. Extracts and fractions from Handroanthus showed cytotoxicity against the following tumor cell lines: HL-60, MDA-MB-435, MDA-MB-231, MCF-7, HT-29, HCT-8, HCT-116, HEp-2, HepG2, CACO-2, SF-295, NCI-H292, NCI-H460, HeLa, and OVCAR-8. ß-Lapachone, a naphthoquinone isolated from some species of this genus, is the most investigated compound for anticancer potential and has proved effective against some lung cancer cell lines (CL1-1, CL1-5 and A549). Results related to toxicological studies were not conclusive, considering that some extracts and compounds isolated from plants of this genus may present some degree of toxicity depending on the time of use and the concentration/dose used. Thus, despite the promising effects against various cancer cell lines, caution is needed when making use of these products.

Myocardial Bridging Leading to Cardiac Collapse in a Marathon Runner.

Myocardial bridging (MB) is a congenital coronary anomaly, which is defined as cardiac muscle overlying a portion of a coronary artery. Although traditionally considered benign in nature, increasing attention is being given to specific subsets of MB. Sports medicine recognizes MB as a cause of sudden death among young athletes. We present a case of a 30-year-old man who suddenly collapsed during a marathon running. Diagnostic workup with coronary computed tomography angiography revealed the presence of three simultaneous myocardial bridges in this patient, possibly explaining the exercise-induced syncope. The other diagnostic tests excluded seizures, cranioencephalic lesions, ionic or metabolic disturbances, acute coronary syndromes, cardiomyopathies, myocarditis, or conduction disturbances. Exertional syncope is a high-risk complaint in the marathon runner. In the context of intense physical activity, the increased sympathetic tone leading to tachycardia and increased myocardial contractility facilitates MB ischemia. In this illustrative case, the patient's syncope might probably be associated with an ischemia-induced arrhythmia secondary to MB and potentiated by dehydration in the context of prolonged stress (marathon running). In conclusion, this case highlights that MB may be associated with dangerous complications (myocardial ischemia and life-threatening ventricular arrhythmias), particularly during intense physical activity and in the presence of a long myocardial bridge.

Traditional Uses, Phytochemistry, and Bioactivities of Mesosphaerum suaveolens (L.) Kuntze.

Mesosphaerum suaveolens (L.) Kuntze is a species widely used traditionally in the treatment of ailments, such as stomach pain, hemorrhoids, cough, verminosis, ulcer, liver disease, fever, influenza, nasal congestion, and inflammation. This review aims to provide a survey of available information on seven international electronic databases (Google Scholar, Medline, ResearchGate, Web of Science, Scopus, Science Direct, and PubMed) about botanical aspects, traditional uses, phytochemistry, and biological activities of M. suaveolens. Mesosphaerum suaveolens is a tropical America native species, but it can be found in several parts of the world as a ruderal plant. The species is the most studied species of the genus Lamiaceae due its phytochemical aspect, especially regarding the chemical composition of its essential oil. Besides the essential oils, M. suaveolens is a source of numerous secondary compounds such as triterpenes, diterpenes, and phenolic compounds, which are related to its biological activities, such as allelopathic, antibacterial, antifungal, insecticidal, and larvicidal activities as described in the literature.

Phytochemistry and teratogenic potential of Mimosa tenuiflora (willd.) poir. (Fabaceae) in ruminants: A systematic review.

Mimosa tenuiflora (Willd.) Poir. (Fabaceae) is a plant native to Brazil and occurs in the phytogeographic domains of Caatinga and Cerrado. Relevant studies have investigated the chemical components of this plant and others have already demonstrated its teratogenic potential. It has been proven that this plant causes congenital malformations in farm animals and, consequently, financial losses to farmers in the Brazilian semiarid region. The present work aimed to carry out a bibliographic survey on the teratogenic effects of M. tenuiflora in ruminants and to group the chemical compounds occurring in this species. For this, databases were consulted and twenty-four articles published in the last 30 years (1990-2020) were included. According to the scientific documents analyzed, M. tenuiflora has embryotoxic, fetotoxic and abortive potential in farm animals, especially sheep and goats. The main classes of chemical compounds present in this species are alkaloids, saponins, flavonoids, and terpenoids. It is likely that some of these substances, mainly the indole alkaloid N,N-dimethyltryptamine, are related to the teratogenic effects reported in ruminants in the Brazilian semiarid region.

Alkaloids of the Lauraceae.

This chapter presents an overview of the chemistry and pharmacology of the alkaloids found in species of the Lauraceae family. The occurrence of alkaloids from Lauraceae species as well as their chemical structures is summarized in informative and easy-to-understand tables. Within the Lauraceae family, the genera Ocotea (195), Litsea (180), Cryptocarya (133), and Neolitsea (110) have led to the greater number of publications regarding alkaloids content. Valuable and comprehensive information about the structure of these alkaloids is provided. The alkaloids of the aporphine type, found in 22 of the 23 genera, represent the predominant group in this family. Many of the isolated alkaloids exhibit unique structures. From plants of this family, 22 different types of skeletons have been isolated, among them only the purine alkaloids are classified as pseudoalkaloids, and the types phenethylamines, phenethylcinnamides, and phthalidoisoquinoline are classified as protoalkaloids. The chapter is presented as a contribution for the scientific community, mainly to enable the search for alkaloids in species belonging to the Lauraceae family.

Hematological evaluation of free-living golden-headed lion tamarins (Leontopithecus chrysomelas) from an Urban Atlantic Forest.

BACKGROUND: The Atlantic Forest where the animals were captured is surrounded by residences, so this close contact could favor the presence of disease-transmitting pathogens, putting the local population at risk. For these and other factors, it is important to perform laboratory tests enabling the performance of important diagnoses. METHODS: Blood samples of 268 golden-headed lion tamarins (Leontopithecus chrysomelas) inhabiting an Atlantic Forest area in Rio de Janeiro, Brazil, were processed for accessing age and sex influence in hematological parameters and to establish normative hematology values. RESULTS: Mean values of red blood cells, hematocrit, hemoglobin, and platelet count were significantly higher in adult males than in adult females. Adult animals had significantly higher mean neutrophil count, and young animals had higher averages than adults in lymphocyte values. Anisocytosis and platelet indices parameters were also provided for the first time. CONCLUSIONS: Averages presented can be used as hematological parameters for golden-headed lion tamarins.

Revised version of the Scale of Evaluation of Reading Competence by the Teacher: final validation and standardization / Versión revisada de la Escala de Evaluación de la Competencia de Lectura por el Profesor: validación final y estandarización

The original version of the EACOL, a tool for teachers to assess silent and aloud reading of Brazilian 2nd-to-5th-graders, was revised and the resulting instrument was validated and normalized. Method: 72 teachers were asked to answer the revised EACOL and a behavioral questionnaire; 452 pupils performed a test battery composed by seven reading tasks and one general cognitive ability measure. Results: The revised EACOL presented high reliability and moderate-to-strong correlations with all reading variables; cluster analysis suggested three proficiency groups (poor/not-so-good/good readers). Conclusion: in agreement with previous studies, teachers, when provided with sound criteria, can come to reliable evaluations of their students' reading ability. Thus, an improved instrument, with evidence of reliability as well as content, internal and external validity, is offered to allow an indirect assessment of the reading ability of schoolchildren. This instrument can easily be adapted to other Portuguese-speaking countries.

La versión original de EACOL es una herramienta para que los profesores evalúen la lectura silenciosa y en voz alta de los estudiantes brasileños del segundo al quinto año escolar, esta fue revisada, validada y estandarizada. Método: 72 profesores respondieron la escala EACOL y un cuestionario de comportamiento; 452 estudiantes respondieron siete medidas de lectura y una de capacidad cognitiva general. Resultados: la revisión de EACOL mostró una alta confiabilidad y correlaciones de moderadas a fuertes con todas las variables de lectura. Análisis de clusters sugirió tres grupos de competencia (lector de baja/media/alta). Conclusión: de acuerdo con estudios anteriores, los profesores pueden hacer evaluaciones confiables de la capacidad de lectura de sus estudiantes, cuando se proporciona criterios operacionales. De esta manera, se ofrece un instrumento mejorado para evaluar indirectamente la lectura de niños, con evidencias de fiabilidad interna y externa validez de contenido. Este instrumento se puede adaptar fácilmente a otros países de lengua portuguesa.

[Anomalous origin of the right coronary artery and acute myocardial infarction: cause or coincidence?]. / Origem anómala da coronária direita e enfarte agudo do miocárdio: causa ou coincidência?

Congenital coronary artery anomalies are one of the causes of myocardial ischemia and sudden death in the young, mainly during sports. Origin of the right coronary artery from the left anterior descending artery is very rare, with a prevalence of 0.015%, corresponding to 1.2% of all coronary artery anomalies. The authors present the case of a 22-year-old man, with a history of cocaine use, admitted to hospital with a non-ST elevation acute myocardial infarction. Coronary angiography revealed the presence of this rare coronary anomaly and the absence of atherosclerotic luminal stenosis, and so it was assumed to be a type II infarction caused by cocaine-induced vasospasm of the anomalous vessel.

Randomized comparison of safety and pharmacokinetics of caspofungin, liposomal amphotericin B, and the combination of both in allogeneic hematopoietic stem cell recipients.

The combination of liposomal amphotericin B (LAMB) and caspofungin (CAS) holds promise to improve the outcome of opportunistic invasive mycoses with poor prognosis. Little is known, however, about the safety and pharmacokinetics of the combination in patients at high risk for these infections. The safety and pharmacokinetics of the combination of LAMB and CAS were investigated in a risk-stratified, randomized, multicenter phase II clinical trial in 55 adult allogeneic hematopoietic stem cell recipients (aHSCT) with granulocytopenia and refractory fever. The patients received either CAS (50 mg/day; day 1, 70 mg), LAMB (3 mg/kg of body weight/day), or the combination of both (CASLAMB) until defervescence and granulocyte recovery. Safety, development of invasive fungal infections, and survival were assessed through day 14 after the end of therapy. Pharmacokinetic sampling and analysis were performed on days 1 and 4. All three regimens were well tolerated. Premature study drug discontinuations due to grade III/IV adverse events occurred in 1/18, 2/20, and 0/17 patients randomized to CAS, LAMB, and CASLAMB, respectively. Adverse events not leading to study drug discontinuation were frequent but similar across cohorts, except for a higher frequency of hypokalemia with CASLAMB (P < 0.05). Drug exposures were similar for patients receiving combination therapy and those randomized to monotherapy. There was no apparent difference in the occurrence of proven/probable invasive fungal infections and survival through day 14 after the end of therapy. CASLAMB combination therapy in immunocompromised aHSCT patients was as safe as monotherapy with CAS or LAMB and had similar plasma pharmacokinetics, lending support to further investigations of the combination in the management of patients with invasive opportunistic mycoses.

Atrial fibrillation ablation: importance of cavotricuspid isthmus block.

INTRODUCTION AND OBJECTIVE: Maintenance of atrial fibrillation (AF) depends on the presence of multiple reentrant circuits in the atria. In AF ablation, after pulmonary vein (PV) isolation, substrate modification can be increased by performing linear lesions in the left atrium that reduce the fibrillatory surface. A cavotricuspid isthmus (CTI) block may be an easier and safer alternative to left atrial lines for this purpose. Non-inducibility after AF ablation is associated with a higher success rate. The aim of this study is to assess whether CTI ablation after PV isolation reduces inducibility of atrial arrhythmias, particularly AF. METHODS AND RESULTS: In 29 consecutive patients (23 male, mean age 54.6+/-11.4 years, 11 (38%) with hypertension and four (14%) with structural heart disease, mean left atrial dimension 43+/-6 mm) undergoing PV isolation for paroxysmal or persistent AF, atrial arrhythmia inducibility was tested before and after CTI ablation. The procedure was performed using a CARTO-Merge mapping system, one or two Lasso catheters, an irrigated ablation catheter and radiofrequency energy. Atrial arrhythmia inducibility was tested with burst pacing down to 150 ms or atrial refractoriness from the proximal coronary sinus. Atrial arrhythmias were considered inducible if they persisted for more than 60 seconds. Of the 29 patients, 26 (90%) had an inducible arrhythmia before CTI ablation--AF in 16, typical atrial flutter (AFL) in seven and atypical AFL in three. Three (10%) were non-inducible. After CTI ablation, only 11 patients (38%) maintained arrhythmia inducibility (p<0.001)--AF in nine and atypical AFL in two. There was a significant reduction of AF inducibility (16 vs. 9/29, p=0.016) and of combined AF and atypical AFL inducibility (19 vs. 11/29, p=0.021). After one year of follow-up, 23 patients (79%) had no recurrence of arrhythmia. Success rates were 83% in patients without and 73% in patients with inducible arrhythmias at the end of the procedure (p=NS). CONCLUSION: CTI ablation, in addition to PV isolation, significantly reduced the number of patients with inducible atrial arrhythmias and inducible AF.

Phase II study of gemcitabine in children with solid tumors of mesenchymal and embryonic origin.

The therapeutic benefit and side-effect profile of gemcitabine in adults with relapsed solid tumors is well known. So far, few data are available about its significance in pediatric relapsed solid tumors. To determine the efficacy and tolerability of gemcitabine in children, the drug was administered by intravenous short-term infusion over 30 min at a dose of 1200 mg/m2 weekly for 3 weeks as one cycle in children with relapsed solid tumor of embryonic or mesenchymal origin. From May 2003 to September 2004, 14 male and six female patients (2-23, median 15.8 years) were recruited for this prospective open-label phase II study (two-step Simon design). The patients suffered from rhabdomyosarcoma (n=8), Ewing's sarcoma (n=4), osteosarcoma (n=2), neuroblastoma (n=3), hepatoblastoma (n=2) and nephroblastoma (n=1). Median duration of therapy was 27.5 days (7-99), corresponding to 4.0 (2-11) infusions of gemcitabine. Two patients (neuroblastoma and Ewing) had stable disease documented for 69 and 70 days, whereas no objective responses were observed. In 34/94 administered infusions; doses had to be reduced or omitted for grade 3-4 hematotoxicity. Minimal activity was observed in this cohort of children with a wide spectrum of mesenchymal and embryonic tumors. Given the relatively low dose of gemcitabine administered, this study does not exclude the possibility of activity at higher doses. Secondly, the tolerability of gemcitabine in children was consistent with that expected in adults. For further studies in this population, we recommend the use of gemcitabine in combination with other agents.

Serum asparaginase activities and asparagine concentrations in the cerebrospinal fluid after a single infusion of 2,500 IU/m(2) PEG asparaginase in children with ALL treated according to protocol COALL-06-97.

BACKGROUND AND PROCEDURE: Pharmacological surrogate parameters are considered a useful tool in estimating the treatment intensity of asparaginase (ASNase) preparations. When a pegylated ASNase (single infusion of 2,500 IU/m(2) polyethylene glycol (PEG)-ASNase, Oncaspar) was introduced into the treatment protocols of the German Cooperative Acute Lymphoblastic Leukaemia (COALL) study group, this was accompanied by a drug monitoring programme measuring serum ASNase activity and asparagine (ASN) concentrations in the cerebrospinal fluid (CSF) in 70 children. RESULTS: Four hundred fifty-nine serum samples from 67 evaluable patients showed medians of ASNase activity of 1,189.5, 824.5, 310.5, 41 and 4 U/l on day 7 +/- 1, 14 +/- 1, 21 +/- 1, 28 +/- 1 and 35 +/- 1 respectively. One hundred eighty-four samples from 59 patients were evaluable for ASN concentrations in the CSF. The medians of ASN concentration were <0.2, 0.2, 0.9 and 3.2 microM on day 14 +/- 1, 21 +/- 1, 28 +/- 1 and 35 +/- 1 respectively. When relating CSF ASN levels to the serum ASNase activity measured on the same day, a median of 1.2 microM CSF ASN was associated with values of serum ASNase activity between > or =2.5 and <100 U/l. Serum ASNase activity values > or =100 U/l were associated with a median CSF ASN of <0.2 microM, with 13/27 samples being incompletely depleted. CONCLUSIONS: The treatment intensity achieved with PEG ASNase in the present study appears to be acceptable based on the surrogate of serum ASNase activity. However, the pharmacological objective of ASNase treatment, that is, complete CSF ASN depletion with an ASNase activity >100 U/l, was not ensured. Nevertheless, one must also be aware that the minimum ASN concentration required for leukaemic cell growth is yet to be established.

Asparagine concentration in plasma after 2,500 IU/m(2) PEG-asparaginase i.v. in children with acute lymphoblastic leukemia.

UNLABELLED: Polyethylene glycol conjugated asparaginase (PEG-ASNase) can be substituted in cases of hypersensitivity to native Escherichia coli asparaginase. We measured asparagine (asn) levels in plasma after a single dose of 2,500 IU/m(2) i.v. PEG-ASNase (Oncaspar) in consolidation treatment of ALL and compared those with data from the previous protocol COALL-05-92. This protocol was similar to COALL-06-97, except that children had been given 45,000 IU/m(2) C-ASNase instead of PEG-ASNase. PATIENTS AND METHODS: Between May 2000 and December 2001 seventy-one children (38 boys, 33 girls) with newly diagnosed ALL treated according to the multicenter protocol COALL-06-97 were investigated in this study. Four hundred and seventy-four plasma samples (71 patients) were analysed by ion exchange chromatography after column derivatization with o-phthaldialdehyde. For comparison data (350 plasma samples) from 51 patients treated according to the protocol COALL-05-92 were available. The same method for detection of asn in plasma was used. RESULTS: The median asparagine level in plasma after 2,500 IU/m(2) PEG-ASNase i.v. was below the limit of detection for at least 5 weeks in 81 % of the patients. When divided into high risk (HR) and low risk (LR) group, HR patients who had previously received one dose more of C-ASNase showed a markedly shorter depletion than the LR patients compatible with a higher risk of antibody formation and consequent silent inactivation after a higher number of exposures to ASNase. In the previous protocol COALL-05-92 median asn levels in plasma after 45,000 IU/m(2) native C-ASNase i.v. were below the limit of detection for at least 5 weeks in 65 % of the patients. CONCLUSIONS: 2,500 IU/m(2) PEG-ASNase led to an equally long depletion of asn in plasma as did 45,000 IU/m(2) native C-ASNase i.v. used in COALL-05-92.

Drug monitoring of PEG-asparaginase treatment in childhood acute lymphoblastic leukemia and non-Hodgkin's lymphoma.

This is an updated review of the pharmacokinetic profile of PEG-asparaginase (PEG-ASNase) in childhood acute lymphoblastic leukemia (ALL) or non-Hodgkin's lymphoma (NHL). In a total of 271 children undergoing ALL/NHL or relapsed ALL treatment according to the Berlin-Frankfurt-Münster (BFM) protocols, drug monitoring of ASNase serum activity was performed after PEG-ASNase infusions. From December 1996 to July 2000, 1667 samples after 362 intravenous administrations of either 500, 750, 1000 or 2500 IU/m2 PEG-ASNase were analyzed. Three weeks after infusion when relating the ASNase activity to the four-dose levels significant differences were not observed. Large interpatient variability was seen at each dose level resulting in a relevant number of patients not achieving adequate treatment intensity. Neither the extent of ASNase pre-treatment nor a prior event of a hypersensitivity reaction against unmodified ASNase had any impact on PEG-ASNase pharmacokinetics. It is concluded that escalation of the dose of PEG-ASNase did not result in a significant prolongation of time with activity values considered therapeutic. Depending on the desired endpoint, a second administration of PEG-ASNase seems to be more favorable than increasing the dose. For a safer recommendation, further investigations assessing the pharmacodynamic profile are required. Drug monitoring is advisable for early detection of patients with rapid elimination in order to ensure maximum treatment intensity.

Analytical validation of a microplate reader-based method for the therapeutic drug monitoring of L-asparaginase in human serum.

The enzyme L-asparaginase (ASNASE), which hydrolyzes L-asparagine (L-Asn) to ammonia and L-aspartic acid (L-Asp), is commonly used for remission induction in acute lymphoblastic leukemia. To correlate ASNASE activity with L-Asn reduction in human serum, sensitive methods for the determination of ASNASE activity are required. Using L-aspartic beta-hydroxamate (AHA) as substrate we developed a sensitive plate reader-based method for the quantification of ASNASE derived from Escherichia coli and Erwinia chrysanthemi and of pegylated E. coli ASNASE in human serum. ASNASE hydrolyzed AHA to L-Asp and hydroxylamine, which was determined at 710 nm after condensation with 8-hydroxyquinoline and oxidation to indooxine. Measuring the indooxine formation allowed the detection of 2 x 10(-5)U ASNASE in 20 microl serum. Linearity was observed within 2.5-75 and 75-1,250 U/L with coefficients of correlation of r(2)>0.99. The coefficients of variation for intra- and interday variability for the three different ASNASE enzymes were 1.98 to 8.77 and 1.73 to 11.0%. The overall recovery was 101+/-9.92%. The coefficient of correlation for dilution linearity was determined as r(2)=0.986 for dilutions up to 1:20. This method combined with sensitive methods for the quantification of L-Asn will allow bioequivalence studies and individualized therapeutic drug monitoring of different ASNASE preparations.