Nonbacterial thrombotic endocarditis of mitral valve associated with a lymphoproliferative malignancy: case report and literature review.

BACKGROUND: Non-bacterial thrombotic endocarditis (NBTE) is a rare condition marked by sterile vegetations on cardiac valves, often linked to rheumatologic diseases, autoimmune disorders, and advanced solid malignancies. An early diagnosis and treatment of the associated clinical condition are mandatory, although they do not usually eliminate valvular vegetations, making anticoagulation essential to prevent embolic events. Despite variability, the prognosis of NBTE is usually unfavorable due to recurrent embolic events and the severity of the primary condition, typically advanced cancer. CASE PRESENTATION: We present a case of a 57 years-old male who presented to the emergency department with a 5-day history of painful bilateral digital edema and color change episodes (from pallor to cyanosis). Physical examination revealed erythrocyanosis in the distal extremities, prompting consideration of secondary Raynaud syndrome. Despite medical therapy, progressive digital ischemia led to multiple finger amputations. During etiological investigation, anticoagulation tests and autoimmune analysis yielded negative results. A transesophageal echocardiogram was performed, revealing an irregular hyperechogenic mass on the anterior leaflet of the mitral valve without valve dysfunction, and a thoracic computed tomography scan with contrast showed an enlarged right paratracheal lymph node. Histopathological analysis from a transthoracic needle biopsy of the paratracheal lymph node revealed diffuse large B-cell lymphoma. The patient underwent aggressive R-CHOP chemotherapy, achieving a favorable complete response. CONCLUSION: This is a particular case involving the occurrence of NBTE and Raynaud phenomenon as the initial paraneoplastic manifestations in a previously healthy young man. Reports of NBTE associated with lymphoproliferative conditions are quite rare, with fewer than ten cases described in the literature. To our knowledge, this is the first case of NBTE specifically associated with diffuse large B-cell lymphoma.

Worrisome trends of ST-elevation myocardial infarction during the Covid-19 pandemic: Data from Portuguese centers.

Introduction: During the Covid-19 pandemic there has been a general belief that hospital admissions for non-infectious causes, especially cardiovascular diseases, have fallen. Objectives: To assess the impact of the pandemic on admissions for ST-elevation myocardial infarction (STEMI) during the first pandemic wave. Methods: We performed a multicenter retrospective analysis of consecutive patients presenting with STEMI in two Portuguese hospital centers in two sequential periods - P1 (March 1 to April 30) and P2 (May 1 to June 30). Patient's clinical data and hospital outcomes were compared between the years 2017 to 2019 and 2020 for both periods. Results: During P1 in 2020, a reduction in the number of STEMI patients was observed in comparison with previous years (26.0±4.2 vs. 16.5±4.9 cases per month; p=0.033), as well as an increase in the number of mechanical complications (0.0% vs. 3.0%; p=0.029). Percutaneous coronary interventions in the setting of failed thrombolysis were more frequent (1.9% vs. 9.1%; p=0.033). An overall trend for longer delays in key timings of STEMI care bundles was noted. Mortality was higher during P1 compared to previous years (1.9% vs. 12.1%; p=0.005). Conclusions: During the first Covid-19 wave fewer patients presented with STEMI at the catheterization laboratory for percutaneous coronary intervention. These patients presented more mechanical complications and higher mortality.

Introdução: Recentemente durante a pandemia por Covid-19 houve uma perceção global de uma diminuição de admissões hospitalares por causas não infeciosas, em particular por doenças cardiovasculares. Objetivos: Avaliar o impacto da pandemia nas admissões por enfarte agudo do miocárdio com supradesnivelamento de ST (STEMI), na primeira onda da pandemia. Métodos: Análise multicêntrica e retrospetiva de doentes consecutivos admitidos em dois hospitais portugueses por STEMI em dois períodos sequenciais - P1 (1 de março a 30 de abril) e P2 (1 de maio a 30 de junho). Foi realizada uma comparação dos dados clínicos e de evolução hospitalar entre 2017 a 2019 e 2020 para os dois períodos. Resultados: No P1 de 2020 observou-se, relativamente a anos prévios, uma redução do número de doentes com STEMI (26,0±4,2 versus 16,5±4,9 casos por mês; p=0,033) e um aumento do número de complicações mecânicas (0,0% versus 3,0%; p=0,029). Os casos de angioplastia após trombólise falhada foram mais frequentes (1,9% versus 9,1%; p=0,033). Observou-se uma tendência global para um maior atraso nos tempos-chave de abordagem de doentes com STEMI. A taxa de mortalidade destes doentes no P1 foi superior comparativamente a anos prévios (1,9% versus 12,1%; p=0,005). Conclusões: Durante a primeira onda da pandemia Covid-19 houve uma redução do número de doentes submetidos a angioplastia coronária por STEMI. Esses apresentaram mais complicações mecânicas e uma maior mortalidade.

Diagnóstico do bruxismo infantil: uma revisão da literatura para auxiliar o cirurgião-dentista / Diagnosis of infant bruxism: a review of the literature to assist the dentistry Laura

Objetivo: analisar a literatura pertinente sobre diagnóstico do bruxismo infantil, a fim de auxiliar o cirurgião- -dentista em como detectar esta condição. Materiais e métodos: através das bases de dados PubMed, SciELO e Lilacs, com termos específicos, foi revisada a literatura e realizada a seleção de artigos mais relevantes, por dois examinadores independentes. Os critérios incluíram crianças com bruxismo, de 0 a 12 anos, independentemente de sexo, ano ou contexto geográfico. Resultados: inicialmente, 1.409 artigos foram identificados. Após a exclusão de duplicatas, avaliação dos títulos, resumos e textos completos, foram selecionados 42 artigos. Uma tabela foi delineada para extrair dados e através desta foram mapeados os estudos. Questionários/ relatos dos responsáveis foram os métodos mais utilizados para diagnóstico de bruxismo infantil, relatados na literatura, 21 artigos, e associados com exame clínico, 16 artigos. A polissonografia foi utilizada em 5 artigos, sendo 2 exclusivamente, 1 em revisão sistemática e 2 associados com questionário aos responsáveis. Os indicadores da Associação Americana de Medicina do Sono (AASM) foram utilizados em 9 artigos. Conclusão: a associação entre exame clínico/relato dos responsáveis, com critérios específicos, sugere uma boa conduta para o cirurgião-dentista, embora a polissonografia seja considerada o método padrão-ouro, pois independe de condições financeiras e manejo, principalmente por se tratar de crianças.(AU)

Objective: to analyze the pertinent literature about diagnosis of children bruxism, in order to assist the dental professional in the recognition this condition. Materials and methods: through databases PubMed, Web of Science, SciELO, Lilacs, searching specific terms the literature, was reviewed and article selection was carried out by two independent examiners. The criteria established for searching were children from 0 to 12 years of age, independetly of sex, year or geographical context. Results: initially, 1409 articles were identified. After the exclusion of duplicates, evaluation of titles, abstracts and full text, 42 articles were totaled. A table was drawn to extract data and through this the studies were mapped. Questionnaires and reports from guardians were the most used method for detected diagnosis of childhood bruxism, reported in the literature, 21 articles, and associated with clinical examination, 16 articles. Polysomnography was used in 5 articles, 2 exclusively, 1 in a systematic review and 2 associated with a questionnaire to those responsible. The indicators of the American Sleep Medicine Association (AASM) were used in 9 articles. Conclusion: the association between clinical examination and report of parents, with a specific criteria, suggests a good conduct for the dentist. Although polysomnography is considered the gold standard method, as it depends on financial conditions and management, mainly in the case of children.(AU)

Usefulness of Routine Fractional Flow Reserve for Clinical Management of Coronary Artery Disease in Patients With Diabetes.

Importance: Approximately one-third of patients considered for coronary revascularization have diabetes, which is a major determinant of clinical outcomes, often influencing the choice of the revascularization strategy. The usefulness of fractional flow reserve (FFR) to guide treatment in this population is understudied and has been questioned. Objective: To evaluate the usefulness and rate of major adverse cardiovascular events (MACE) of integrating FFR in management decisions for patients with diabetes who undergo coronary angiography. Design, Setting, and Participants: This cross-sectional study used data from the PRIME-FFR study derived from the merger of the POST-IT study (Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease [March 2012-November 2013]) and R3F study (French Study of FFR Integrated Multicenter Registries Implementation of FFR in Routine Practice [October 2008-June 2010]), 2 prospective multicenter registries that shared a common design. A population of all-comers for whom angiography disclosed ambiguous lesions was analyzed for rates, patterns, and outcomes associated with management reclassification, including revascularization deferral, in patients with vs without diabetes. Data analysis was performed from June to August 2018. Main Outcomes and Measures: Death from any cause, myocardial infarction, or unplanned revascularization (MACE) at 1 year. Results: Among 1983 patients (1503 [77%] male; mean [SD] age, 65 [10] years), 701 had diabetes, and FFR was performed for 1.4 lesions per patient (58.2% of lesions in the left anterior descending artery; mean [SD] stenosis, 56% [11%]; mean [SD] FFR, 0.81 [0.01]). Reclassification by FFR was high and similar in patients with and without diabetes (41.2% vs 37.5%, P = .13), but reclassification from medical treatment to revascularization was more frequent in the former (142 of 342 [41.5%] vs 230 of 730 [31.5%], P = .001). There was no statistical difference between the 1-year rates of MACE in reclassified (9.7%) and nonreclassified patients (12.0%) (P = .37). Among patients with diabetes, FFR-based deferral identified patients with a lower risk of MACE at 12 months (25 of 296 [8.4%]) compared with those undergoing revascularization (47 of 257 [13.1%]) (P = .04), and the rate was of the same magnitude of the observed rate among deferred patients without diabetes (7.9%, P = .87). Status of insulin treatment had no association with outcomes. Patients (6.6% of the population) in whom FFR was disregarded had the highest MACE rates regardless of diabetes status. Conclusions and Relevance: Routine integration of FFR for the management of coronary artery disease in patients with diabetes may be associated with a high rate of treatment reclassification. Management strategies guided by FFR, including revascularization deferral, may be useful for patients with diabetes.

Impact of Routine Fractional Flow Reserve on Management Decision and 1-Year Clinical Outcome of Patients With Acute Coronary Syndromes: PRIME-FFR (Insights From the POST-IT [Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease] and R3F [French FFR Registry] Integrated Multicenter Registries - Implementation of FFR [Fractional Flow Reserve] in Routine Practice).

BACKGROUND: Fractional flow reserve (FFR) is not firmly established as a guide to treatment in patients with acute coronary syndromes (ACS). Primary goals were to evaluate the impact of integrating FFR on management decisions and on clinical outcome of patients with ACS undergoing coronary angiography, as compared with patients with stable coronary artery disease. METHODS AND RESULTS: R3F (French FFR Registry) and POST-IT (Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease), sharing a common design, were pooled as PRIME-FFR (Insights From the POST-IT and R3F Integrated Multicenter Registries - Implementation of FFR in Routine Practice). Investigators prospectively defined management strategy based on angiography before performing FFR. Final decision after FFR and 1-year clinical outcome were recorded. From 1983 patients, in whom FFR was prospectively used to guide treatment, 533 sustained ACS (excluding acute ST-segment-elevation myocardial infarction). In ACS, FFR was performed in 1.4 lesions per patient, mostly in left anterior descending (58%), with a mean percent stenosis of 58±12% and a mean FFR of 0.82±0.09. In patients with ACS, reclassification by FFR was high and similar to those with non-ACS (38% versus 39%; P=NS). The pattern of reclassification was different, however, with less patients with ACS reclassified from revascularization to medical treatment compared with those with non-ACS (P=0.01). In ACS, 1-year outcome of patients reclassified based on FFR (FFR against angiography) was as good as that of nonreclassified patients (FFR concordant with angiography), with no difference in major cardiovascular event (8.0% versus 11.6%; P=0.20) or symptoms (92.3% versus 94.8% angina free; P=0.25). Moreover, FFR-based deferral to medical treatment was as safe in patients with ACS as in patients with non-ACS (major cardiovascular event, 8.0% versus 8.5%; P=0.83; revascularization, 3.8% versus 5.9%; P=0.24; and freedom from angina, 93.6% versus 90.2%; P=0.35). These findings were confirmed in ACS explored at the culprit lesion. In patients (6%) in whom the information derived from FFR was disregarded, a dire outcome was observed. CONCLUSIONS: Routine integration of FFR into the decision-making process of ACS patients with obstructive coronary artery disease is associated with a high reclassification rate of treatment (38%). A management strategy guided by FFR, divergent from that suggested by angiography, including revascularization deferral, is safe in ACS.

Impact of Routine Fractional Flow Reserve Evaluation During Coronary Angiography on Management Strategy and Clinical Outcome: One-Year Results of the POST-IT.

BACKGROUND: Penetration of fractional flow reserve (FFR) in clinical practice varies extensively, and the applicability of results from randomized trials is understudied. We describe the extent to which the information gained from routine FFR affects patient management strategy and clinical outcome. METHODS AND RESULTS: Nonselected patients undergoing coronary angiography, in which at least 1 lesion was interrogated by FFR, were prospectively enrolled in a multicenter registry. FFR-driven change in management strategy (medical therapy, revascularization, or additional stress imaging) was assessed per-lesion and per-patient, and the agreement between final and initial strategies was recorded. Cardiovascular death, myocardial infarction, or unplanned revascularization (MACE) at 1 year was recorded. A total of 1293 lesions were evaluated in 918 patients (mean FFR, 0.81±0.1). Management plan changed in 406 patients (44.2%) and 584 lesions (45.2%). One-year MACE was 6.9%; patients in whom all lesions were deferred had a lower MACE rate (5.3%) than those with at least 1 lesion revascularized (7.3%) or left untreated despite FFR≤0.80 (13.6%; log-rank P=0.014). At the lesion level, deferral of those with an FFR≤0.80 was associated with a 3.1-fold increase in the hazard of cardiovascular death/myocardial infarction/target lesion revascularization (P=0.012). Independent predictors of target lesion revascularization in the deferred lesions were proximal location of the lesion, B2/C type and FFR. CONCLUSIONS: Routine FFR assessment of coronary lesions safely changes management strategy in almost half of the cases. Also, it accurately identifies patients and lesions with a low likelihood of events, in which revascularization can be safely deferred, as opposed to those at high risk when ischemic lesions are left untreated, thus confirming results from randomized trials. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01835808.

Second-generation versus first-generation drug-eluting stents for the treatment of patients with acute coronary syndromes and obstructive coronary artery disease.

INTRODUCTION AND AIMS: Randomized trials and registries have shown that drug-eluting stents (DES) have an overall better performance than bare-metal stents in patients treated in the setting of both ST-segment and non-ST-segment elevation acute coronary syndromes, mainly by reducing restenosis. Whether or not the use of newer second-generation devices (vs. first-generation DES) differs in these high-risk patients remains to be determined. METHODS AND RESULTS: In a single-centre prospective registry, 3266 patients underwent a percutaneous coronary intervention with at least one DES from January 2003 to December 2009. Of these, 1423 (43.6%) were treated in the setting of an acute coronary syndrome, using either first-generation-only DES [paclitaxel or sirolimus; n=923 (64.9%)] or second-generation-only [zotarolimus or everolimus; n=500 (35.1%)]. The occurrence of death from any cause, nonfatal myocardial infarction or target vessel failure (composite primary endpoint) was compared between these two groups; repeat revascularization of the index stented lesion and definite stent thrombosis [according to the academic research consortium (ARC) definition] were assessed as isolated secondary outcomes. At a median follow-up of 598 days (interquartile range 453-1206), the incidence of death was 10.7% (152), 136 patients (9.6%) had a new myocardial infarction and target vessel failure events occurred in 147 patients (10.3%). Disparity in the follow-up duration was accounted for by considering only the 1-year major adverse cardiac event rate (n=161; 11.3%). After adjustment for baseline characteristics using a Cox proportional hazard model, we could not find a significant difference in the incidence of the composite primary endpoint at 1-year between first-generation (10.8%) and second-generation DES (12.2%) [hazard ratio (HR): 1.1; 95% confidence interval (CI): 0.82-1.57, P=0.463], nor in the occurrence of repeat target lesion revascularization (3.6 vs. 4.4%; HR 1.35; 95% CI 0.77-2.34; P=0.293). In a per patient analysis, at 1 year, ARC-definite ST was documented in 1.0% of patients treated with second-generation DES versus 2.8% in those treated with first-generation DES (corrected HR 0.36; 95% CI 0.14-0.94; P=0.037), owing mostly to a higher difference in late ST. CONCLUSION: Our results suggest that both first-generation and second-generation DES seem to be similarly effective in patients undergoing a percutaneous coronary intervention in the setting of acute coronary syndromes. However, newer second-generation devices may offer potential advantages because of a significantly lower incidence of ARC-definite ST.

Stent thrombosis with second- versus first-generation drug-eluting stents in real-world percutaneous coronary intervention: analysis of 3806 consecutive procedures from a large-volume single-center prospective registry.

BACKGROUND AND AIMS: When compared to their first-generation (1stGEN) counterparts, second-generation (2ndGEN) drug-eluting stents (DESs) have been associated with better clinical outcomes in randomized clinical trials, namely by reducing the rates of stent thrombosis (ST). Our goal was to investigate whether or not the broad use of newer devices would translate into higher safety in a real-world population. For that purpose, we compared the occurrence of definite ST at 12 months between two patient subsets from a large-volume single-center registry, according to the type of DES used. Total mortality was a secondary endpoint. METHODS AND RESULTS: Between January 2003 and December 2010, a total of 3806 patients were submitted to percutaneous coronary intervention (PCI) with only 1stGEN or 2ndGEN DES: 2388 patients (62.7%) were treated with 1stGEN DES only (sirolimus-eluting stent [SES] = 1295 [34.0%]; paclitaxel-eluting stent [PES] = 943 [24.8%]; both stent types were used in 150 patients) and 1418 patients (37.3%) were treated with 2ndGEN DESs only. The total incidence of definite ST (as defined by the Academic Research Consortium) at 12 months was 1.2% (n = 46). After correction for baseline differences between study groups and other variables deemed to influence the occurrence of ST, the use of 1stGEN DES was associated with a significant 2.4-fold increase in the risk of definite ST (95% confidence interval [CI], 1.05-5.42; P=.039) at 12 months; adjusted risk was higher with PES (hazard ratio [HR], 3.6; 95% CI, 1.48-8.70; P=.005) than with SES (HR, 2.3; 95% CI, 0.92-5.65; P=.074). Total mortality (3.7% vs 3.5%) did not differ significantly between groups (adjusted HR, 1.2; 95% CI, 0.81-1.84, P=.348). CONCLUSIONS: Our data suggest that in the real-world setting of contemporary PCI, the unrestricted use of newer 2ndGEN DESs translates into an improvement in PCI safety (relative to 1stGEN DESs), with a significantly lower risk of definite ST at 12 months.

Coronary-subclavian steal syndrome: percutaneous approach.

Coronary subclavian steal syndrome is a rare ischemic cause in patients after myocardial revascularization surgery. Subclavian artery stenosis or compression proximal to the internal mammary artery graft is the underlying cause. The authors present a clinical case of a patient with previous history of non-ST elevation myocardial infarction, triple coronary bypass, and effort angina since the surgery, with a positive ischemic test. Coronary angiography revealed a significant stenosis of the left subclavian artery, proximal to the internal mammary graft.

[Streptococcus agalactiae endocarditis]. / Endocardite a Streptococcus agalactiae.

Streptococcus agalactiae endocarditis is a rare clinical entity that is generally characterized by acute onset, the presence of large vegetations, rapid valvular destruction and frequent complications, particularly embolization. Mortality is high with medical therapy alone. The authors present a case report of Streptococcus agalactiae endocarditis in a young patient treated by prompt surgery. The literature is reviewed.

[Coronary artery anomalies]. / Anomalias das artérias coronárias.

Coronary artery anomalies (CAAs) are a rare entity but their true incidence in the general population has yet to be determined. Most CAAs are asymptomatic, but they are nevertheless the second leading cause of sudden death in apparently healthy young athletes. The new imaging methods available to cardiologists, including CT angiography and MRI, now enable noninvasive diagnosis and characterization of these anomalies. The authors review the literature and present a retrospective study of 360 consecutive patients who underwent cardiac CT angiography. Demographic, clinical and angiographic characteristics were studied. The incidence of CAAs in this population was 2.69%. In order to better characterize this disorder, including diagnostic strategy, screening, treatment and prognosis, the authors suggest the establishment of a national registry of cardiac CT angiography. Such a registry would fill the existing gap in information on exams performed in the country, enriching current knowledge about this disease and noninvasive cardiac imaging in Portugal.

Recycling of aluminum and caustic soda solution from waste effluents generated during the cleaning of the extruder matrixes of the aluminum industry.

Anodising industries use a concentrated caustic soda solution to remove aluminum from extruder matrixes. This procedure produces very alkaline effluents containing high amounts of aluminum. The work reported here was focussed on recycling aluminum, as aluminum hydroxide, from these effluents and regenerating an alkaline sodium hydroxide solution. Briefly, the method comprises a dilution step (necessary for reducing the viscosity of the effluent and allowing the subsequent filtration) followed by a filtration to eliminate a substantial amount of the insoluble iron. Then, sulphuric acid was added to neutralize the waste solution down to pH 12 and induce aluminum precipitation. The purity of the aluminum salt was improved after washing the precipitate with deionised water. The characterization of the solid recovered, performed by thermogravimetric analysis, Fourier transform infrared spectroscopy and X-ray diffraction, indicated characteristics typical of bayerite. The proposal method allowed recovering 82% of the aluminum present in the wastewater with high purity (99.5%). Additionally, a sufficiently concentrated caustic soda solution was also recovered, which can be reused in the anodising industries. This procedure can be easily implemented and ensures economy by recycling reagents (concentrated caustic soda solution) and by recovering commercial by-products (aluminum hydroxide), while avoiding environmental pollution.

Modelling of Pb-(TAPS)(x)-(OH)(y) system and refinement of stability constants in the region of lead hydrolysis and lead hydroxide precipitation.

The influence of [(2-hydroxy-1,1-bis(hydroxymethyl)ethyl)amino]-1-propanesulfonic acid (TAPS) on solutions containing lead(II) was studied by direct current polarography (DCP) and glass electrode potentiometry (GEP). The readings were taken at fixed total TAPS to total lead(II) concentration ratios and various pH values, at 25.0+/-0.1 degrees C and ionic strength 0.1M KNO(3). Due to the basic pK(a) of the ligand, which occurs in the pH range where large amount of lead polynuclear species are formed, and the occurrence of ligand adsorption, that disabled the use of high concentrations of TAPS on DCP experiments, GEP and DCP experimental conditions were put to the limit in order to provide the correct Pb-TAPS-OH model and reliable stability constants. The proposed final model is: PbL, PbL(2), PbL(2)(OH) and PbL(2)(OH)(2) with overall stability constants values, as logbeta, 3.27+/-0.06, 6.5+/-0.1, 12.7+/-0.1 and 17.27+/-0.06, respectively. A comparative analysis of the strength of complexation of TAPS and a structural related buffer, 2-hydroxy-3-[tris(hydroxymethyl)methylamino]-1-propanesulfonic acid (TAPSO), with lead is also discussed.

Challenges in modelling and optimisation of stability constants in the study of Cu-(TAPS)(x)-(OH)(y) system by polarography.

This work describes the application of polarography, a technique scarcely used for modelling and optimisation of stability constants, in the study of copper complexes with [(2-hydroxy-1,1-bis(hydroxymethyl)ethyl)amino]-1-propanesulfonic acid (TAPS). Direct current polarography (DCP), using low total copper ion and large total ligand to total copper concentration, enabled the full characterization of Cu-(TAPS)(x)-(OH)(y) system, whose complexation occurs in the pH range of copper hydrolysis and Cu(OH)(2) precipitation. Cu-(TAPS)(x)-(OH)(y) system was studied by DCP and glass electrode potentiometry (GEP) in aqueous solution at fixed total ligand to total metal concentrations ratios and varied pH values (25.0 degrees C; I=0.1M, KNO(3)). The predicted model, as well as the overall stability constants values, are (as logbeta): CuL(+)=4.2, CuL(2)=7.8, CuL(2)(OH)(-)=13.9 and CuL(2)(OH)(2)(2-)=18.94. GEP only allowed confirming the stability constants for CuL(+) and CuL(2) and was used to determine the pK(a) of TAPS, 8.342. Finally, a briefly comparative analysis between TAPS and other structural related buffers was done. Evaluation based on logbeta(CuL) versus pK(a) revealed that TES, TRIS, TAPS and AMPSO coordinated via amino and hydroxymethylgroups forming a five-membered chelate ring. For BIS-TRIS and TAPSO, and possibly DIPSO, one or more five-membered chelate rings involving additional hydroxyl groups are also likely formed.

Interpretation of non-Nernstian slopes in graphic analysis of data collected in pH range close to deprotonation of a ligand Part I. A glass electrode potentiometric and polarographic study of Cd-(TAPSO)x-(OH)y and Zn-(TAPSO)x-(OH)y systems.

In this work, the complexation of cadmium and zinc ions by 3-[N-tris(hydroxymethyl)methylamine]-2-hydroxypropanesulfonic acid (TAPSO), a commercial biological buffer, was evaluated using three electrochemical techniques, at fixed total-ligand and total-metal concentration ratio and varied pH, at 25.0+/-0.1 degrees C and ionic strength set to 0.1M KNO(3). For both metal-ligand systems, complexation was evidenced in the pH range close to deprotonation of the ligand and the final models were optimised after a meticulous graphical analysis. For Cd-(TAPSO)(x)-(OH)(y) system, two complexes, CdL and CdL(2), were identified in the buffering region of the ligand. The proposed final model for this system is: CdL, CdL(2) and CdL(2)(OH) with stability constants, as logbeta, of 2.2, 4.2 and 8.6, respectively. For Zn-(TAPSO)(x)-(OH)(y) system, the complex ZnL is the main species formed in the buffering pH range. The proposed final model is ZnL, ZnL(OH) and ZnL(OH)(2) with overall refined stability constants (as logbeta) to be: 2.5, 7.2 and 13.2, respectively.