Surgical and postsurgical management of abdominal paragangliomas and pheochromocytomas.

PURPOSE: To describe our current protocol for surgical and postsurgical management of abdominal paragangliomas (PGLs) and pheochromocytomas, with a special focus on multidisciplinary management in centres with experience. METHODS: The physicians involved in the management of patients with abdominal PGLs and pheochromocytomas of our hospital reviewed systematically current knowledge on the surgical management of abdominal PGLs and pheochromocytomas. RESULTS: Currently, surgery is considered the treatment of choice for abdominal PGLs and pheochromocytomas. The choice of surgical approach is determined based on the location of the lesion, size, patient́s body habitus and the likelihood of malignancy. Laparoscopic surgery is usually considered the gold standard approach for pheochromocytomas, but open access should be considered in invasive and/or potentially malignant tumours >8-10 cm and for abdominal PGLs. Postsurgical management of pheochromocytomas and PGLs includes close hemodynamic monitoring and treatment of postsurgical complications, the pathological study of the surgical specimen, reassessment of hormonal and/or radiological status and planning of follow-up based on the risk of recurrence and malignancy. CONCLUSION: Surgery represents the treatment of choice of most abdominal PGLs and pheochromocytomas. Optimal postsurgical evaluation, including hemodynamic, pathological, hormonal, and radiological evaluation, should be performed by a multidisciplinary team specializing in PGL/pheochromocytoma management.

Differences in intraoperative and surgical outcomes between normotensive pheochromocytomas and sympathetic paragangliomas (PPGLs) and hypertensive PPGLs: results from the PHEO-RISK STUDY.

PURPOSE: To compare the intraoperative and surgical outcomes of normotensive pheochromocytomas and sympathetic paragangliomas (PPGLs), hypertensive PPGLs and non-PPGL adrenal lesions. METHODS: This a retrospective multicenter cohort study of patients with PPGLs from 18 tertiary hospitals. A control group of histologically confirmed adrenocortical adenomas (non-PPGL group) was selected to compare intraoperative and surgical outcomes with of the normotensive PPGLs. RESULTS: Two hundred and ninety-six surgeries performed in 289 patients with PPGLs were included. Before surgery, 209 patients were classified as hypertensive PPGLs (70.6%) and 87 as normotensive PPGLs. A higher proportion of normotensive PPGLs than hypertensive PPGLs did not receive alpha presurgical blockade (P = 0.009). When we only considered those patients who received presurgical alpha blockers (200 hypertensive PPGLs and 76 normotensive PPGLs), hypertensive PPGLs had a threefold higher risk of intraoperative hypertensive crisis (OR 3.0 [95% 1.3-7.0]) and of hypotensive episodes (OR 2.9 [95% CI 1.2-6.7]) than normotensive PPGLs. When we compared normotensive PPGLs (n = 76) and non-PPGLs (n = 58), normotensive PPGLs had a fivefold higher risk of intraoperative complications (OR 5.3 [95% CI 1.9-14.9]) and a six times higher risk of postoperative complications (OR 6.1 [95% CI 1.7-21.6]) than non-PPGLs. CONCLUSION: Although the risk of intraoperative hypertensive and hypotensive episodes in normotensive PPGLs is significantly lower than in hypertensive PPGLs, normotensive PPGLs have a greater risk of intraoperative and postoperative complications than non-PPGL adrenal lesions. Therefore, it is recommended to follow the standard of care for presurgical and anesthetic management of PPGLs also in normotensive PPGLs.

Tumour size in adrenal tumours: its importance in the indication of adrenalectomy and in surgical outcomes-a single-centre experience.

OBJECTIVE: To evaluate the relevance of tumour size in adrenal tumours in the estimation of malignancy risk and in the outcomes of adrenalectomy. METHODS: We evaluate the histological results and surgical outcomes (intraoperative and postsurgical complications) in a retrospective single-centre cohort of patients without history of active extraadrenal malignancy with adrenal tumours consecutively operated in our centre during January 2010 and December 2020. We compared these results in lesions smaller and larger than 40, 50, and 60 mm. RESULTS: Of 131 patients with adrenal tumours who underwent adrenalectomy, 76 (58.0%) had adrenal masses measuring ≥ 40 mm; 47 were > 50 mm and 28 > 60 mm. The final diagnosis was adrenocortical carcinoma (ACC) in 7 patients, pheochromocytoma in 35, and benign lesions in the remaining. All patients with ACC had adrenal masses > 50 mm, with Hounsfield units > 40 and low lipidic content in the CT. The risk of ACC and pheochromocytoma increased as tumour size did. The diagnostic accuracy of tumour size was quite good for the prediction of ACC (AUC-ROC 0.883). Nevertheless, when only adrenal tumours with HU < 40 were considered, the risk of ACC was 0% independent of tumour size. For pheochromocytomas, the risk was of 8.6% independent of tumour size for lesions with < 20HU. The risk of intraoperative and postoperative complications was independent of tumour size. CONCLUSION: Risk of malignancy and of pheochromocytoma increased as tumour size increased, but, in the presurgical estimation of malignancy risk and of pheochromocytoma, not only tumour size, also lipidic content and other radiological features, should be considered. The risk of complications was independent of tumour size, but hospital stay was longer in patients with complication or open approach.

Protocol for presurgical and anesthetic management of pheochromocytomas and sympathetic paragangliomas: a multidisciplinary approach.

OBJECTIVE: To offer a practical guide for the presurgical and anesthetic management of pheochromocytomas and sympathetic paragangliomas (PGLs). METHODS: This protocol was based on a comprehensive review of the literature and on our own multidisciplinary team's experience from managing pheochromocytoma and sympathetic PGLs at a referral center. RESULTS: Patients with pheochromocytomas and sympathetic paragangliomas (PGLs) may develop potentially life-threatening complications, especially during surgical procedures. A complete biochemical, radiological, genetic, and cardiological assessment is recommended in the preoperative stage as it provides an evaluation of the risk of surgical complications and malignancy, allowing individualization of the presurgical treatment. Treatment with α-blockade and proper volume expansion in the preoperative stage significantly reduces the perioperative morbidity. During surgery, the anesthesiologist should look for a deep anesthetic level that inhibits the cardiovascular effects of catecholamines to minimize the risk of intraoperative complications. CONCLUSIONS: An optimal presurgical evaluation of pheochromocytomas/ sympathetic PGL requires a multidisciplinary approach, including a complete hormonal, radiological, cardiac, genetic, and functioning evaluation in most cases. A proper preoperative evaluation in combination with strict blood pressure and heart rate control, and blood volume status optimization, will significantly reduce the risk of intraoperative and perioperative complications. In those patients who unfortunately develop intraoperative complications, the role of the anesthesiologist is essential since the selection of the appropriate management has a direct impact on morbimortality reduction.

Impact of the COVID-19 pandemic on the surgical activity of Pediatric Urology: analysis of postoperative complications according to the Clavien-Dindo classification. / Repercusión de la pandemia COVID-19 sobre la actividad quirúrgica de Urología Pediátrica: análisis de las complicaciones posquirúrgicas según la clasificación de Clavien-Dindo.

INTRODUCTION AND OBJECTIVE: The coronavirus disease 2019 (COVID-19) has caused a pandemic of global impact that forced social-political measures to be taken, such as the declaration of the state of alarm in Spain. At the same time, the reorganization of the pediatric medical-surgical activities and infrastructures was carried out, with the consequent suspension of the non-urgent surgical activity of Pediatric Urology. We analyzed the impact of the COVID-19 pandemic on surgical activity in a Pediatric Urology division, as well as surgical complications according to the Clavien-Dindo classification. MATERIALS AND METHODS: A systematic review of epidemiological, clinical and surgical data was carried out, including complications and readmissions of all patients operated on in the division of Pediatric Urology within the duration of the state of alarm. Five time periods have been created according to the de-escalation phases. RESULTS: Forty-nine surgical procedures were carried out on 45 patients (8 prior to the implementation of the de-escalation phases). High priority pathologies were the most frequent in the first phases, being the ureteropelvic junction (UPJ) obstruction the most prevalent. Four complications were recorded (8.8%), none of them were respiratory. CONCLUSIONS: The EAU recommendations for the resumption of surgical activity have allowed a correct, safe and gradual transition to the routine surgical activity in Pediatric Urology. The Clavien-Dindo classification is useful and valid for application in this division. No respiratory complications have been reported that could be attributable to the pandemic situation.

Technical challenges of endoscopic treatment for vesicoureteral reflux after Cohen reimplantation. / Consideraciones técnicas en el tratamiento endoscópico del reflujo vesicoureteral tras reimplante tipo Cohen.

INTRODUCTION: The range of indications for endoscopic treatment of vesicoureteral reflux opens more and more until including correction of secondary reflux (VUR) after ureteral reimplantation. However these cases suppose a technical challenge due to postoperative changes. The aim of this work is to present our experience on endoscopic treatment for VUR in ureteral units with Cohen reimplantation surgery, with special interest in the technical peculiarities of the procedure. MATERIAL AND METHODS: A retrospective study of cases of secondary VUR after reimplantation surgery treated by subureteral injection. TECHNIQUE: We put the needle perpendicular to submucous tunnel and inject medially to hole forming a wheal on the anterior face that occludes the meatus RESULTS: During the 1993-2016 period 21 injections were performed in 15 ureteral units. The ureteral pathology included primary VUR (4), duplex system with lower pole reflux (4), megaureter (3) and ureterocele (2). Average patient age was 5.7 years old (2-12). Succesful outcome had been got in 10 ureteral units (66.67%), a decrease of VUR grade in 4 (26.67%) and perseverance/no resolution of grade IV VUR in 1 (6.67%) DISCUSSION: The anti-reflux mechanism of reimplantation depends on optimizing the submucosous tunnel. This subgroup of pacients is small and there are few studies, hindering the agreement on the most appropiate technique. CONCLUSION: Endoscopic treatment of secondary reflux after reimplantation surgery is a procedure with certain technical feature, but safe and effective offering an alternative prior to surgical reoperation.

Understanding the antimicrobial properties/activity of an 11-residue Lys homopeptide by alanine and proline scan.

Previous work demonstrated that lysine homopeptides adopt a polyproline II (PPII) structure. Lysine homopeptides with odd number of residues, especially with 11 residues (K11), were capable of inhibiting the growth of a broader spectrum of bacteria than those with an even number. Confocal studies also determined that K11 was able to localize exclusively in the bacterial membrane, leading to cell death. In this work, the mechanism of action of this peptide was further analyzed focused on examining the structural changes in bacterial membrane induced by K11, and in K11 itself when interacting with bacterial membrane lipids. Moreover, alanine and proline scans were performed for K11 to identify relevant positions in structure conformation and antibacterial activity. To do so, circular dichroism spectroscopy (CD) was conducted in saline phosphate buffer (PBS) and in lipidic vesicles, using large unilamellar vesicles (LUV), composed of 2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) or bacterial membrane lipid. Antimicrobial activity of K11 and their analogs was evaluated in Gram-positive and Gram-negative bacterial strains. The scanning electron microscopy (SEM) micrographs of Staphylococcus aureus ATCC 25923 exposed to the Lys homopeptide at MIC concentration showed blisters and bubbles formed on the bacterial surface, suggesting that K11 exerts its action by destabilizing the bacterial membrane. CD analysis revealed a remarkably enhanced PPII structure of K11 when replacing some of its central residues by proline in PBS. However, when such peptide analogs were confronted with either DMPG-LUV or membrane lipid extract-LUV, the tendency to form PPII structure was severely weakened. On the contrary, K11 peptide showed a remarkably enhanced PPII structure in the presence of DMPG-LUV. Antibacterial tests revealed that K11 was able to inhibit all tested bacteria with an MIC value of 5 µM, while proline and alanine analogs have a reduced activity on Listeria monocytogenes. Besides, the activity against Vibrio parahaemolyticus was affected in most of the alanine-substituted analogs. However, lysine substitutions by alanine or proline at position 7 did not alter the activity against all tested bacterial strains, suggesting that this position can be screened to find a substitute amino acid yielding a peptide with increased antibacterial activity. These results also indicate that the PPII secondary structure of K11 is stabilized by the interaction of the peptide with negatively charged phospholipids in the bacterial membrane, though not being the sole determinant for its antimicrobial activity.

Factors involved in the late failure of endoscopic treatment of vesicoureteral reflux. / Factores implicados en el fracaso tardío del tratamiento endoscópico del reflujo vesicoureteral.

INTRODUCTION: The short-term results of endoscopic treatment of vesicoureteral reflux (VUR) are excellent. Over time, however, a number of patients have been identified for whom VUR reappeared after being resolved with this technique. The aim of this study was to analyse the factors related to this event. MATERIAL AND METHODS: A retrospective, analytical, case-control study included 395 ureteral units with primary VUR treated successfully at our centre, with a minimum follow-up of 3 years. We identified cases in which VUR reappeared and analysed the demographic variables, those related to VUR (grade, laterality, initial study) and those related to the operation (materials used). RESULTS: We identified 77 ureteral units with recurrence in the 395 included units (19.5%). The recurrence rate was 29.7% for the patients treated with dextranomer/hyaluronic acid (Dx/HA), 20.2% for those treated with polydimethylsiloxane (MP) and 12.2% for polytetrafluoroethylene (PTFE). The onset of recurrence rose to 35% for patients treated before 1 year of age and those with gradeV VUR. Urinary dysfunction symptoms also increased the recurrence rate to 34.9%. CONCLUSION: The use of resorbable dextranomer/hyaluronic acid material was related to recurrence in the endoscopic treatment of VUR. The high-grade reflux and treatment at an early age, as well as the presence of urinary dysfunction, are also factors associated with recurrence.

Fisiopatología de la nefropatía diabética: una revisión de la literatura / Pathophysiology of diabetic nephropathy: a literature review

La enfermedad renal crónica es una complicación frecuente en la diabetes mellitus. Su importancia radica en la alta prevalencia y la proyección a futuro que ésta tiene. Se asocia a altos gastos en salud y además a deterioro cardiovascular global. La fisiopatología del desarrollo de esta enfermedad está siendo estudiada y se sabe que en ella participan una serie de vías moleculares complejas que determinan una enfermedad microvascular. En esta revisión se intenta abordar las vías conocidas en el desarrollo de nefropatía diabética, con el fin de comprender mejor posibles blancos terapéuticos que se podrían desarrollar.

Chronic kidney disease is a common complication of diabetes. Its importance lies in its high prevalence and future projection. It is associated with high health costs and global cardiovascular deterioration as well. The development of this disease pathophysiology is being studied and it is known that a series of complex molecular pathways determining a microvascular disease are involved. This review addresses the known pathways in the development of diabetic nephropathy aiming to improve the understanding of potential therapeutic targets that could be developed in the future.

[Genital-urinary rhabdomyosarcoma in childhood: our experience]. / Rabdomiosarcoma genitourinario en la infancia, nuestra experiencia.

INTRODUCTION: Rhabdomyosarcoma (RSM) becomes the most common tumour of the soft tissues during the paediatric age. It represents among 2-3% of child tumours. The genital-urinary location is the second most common location, only after head and neck. The treatment is usually medical, being the surgery a mere contribution, except for the cases in which the situation is not under control, when very aggressive surgery is necessary. The aim of this study is to analyse the cases of genial-urinary RMS that have been treated in our centre and the role that surgery has in their treatment. MATERIAL AND METHODS: Retrospective study of 20 patient (7 girls and 13 boys) with a median age of 24 months (range from 1 month to 12 years) with RMS in the aurochs-genial tract who have been treated in our hospital from 1990 to 2012. The variables described are demographic, location of the primary tumour, state at diagnosis, received treatment, both medical and surgical, with greater emphasis on the kind of surgery applied and monitoring in terms of survival. RESULTS: The location of the primary tumour was: bladder (6), paratesticular (5), vagina (3) retroperitoneal space (3), lesser pelvis (2) and prostate (1). All of them received medical treatment with chemotherapy and radiotherapy following International Society of Pediatric Oncology protocol after diagnostic biopsy. Surgery, which was always used as help, was: reappraisal of biopsy (1), orchiectomy (5), tumoral resection (8) and radical surgery (cystoprostatectomy or pelvic exenteration) in 6 patients. There were 3 deaths, 2 because of the evolution of the disease and 1 because of postoperative sepsis. The survival rate is 80% with a median follow - up of 14 years. CONCLUSIONS: The RMS is the most common tumour of soft tissues in childhood and the genital-urinary location is the second most common after the parameningeal one. The treatment is multidisciplinary and the surgery has a contributing role when there is no answer to the medical treatment or when there is a residual tumour even if some patients do not respond to medical treatment and they need a radical surgery for recovery.

INTRODUCCION: El rabdomiosarcoma (RMS) constituye el tumor de tejidos blandos más frecuente en la edad pediátrica, representando el 2-3% de los tumores infantiles. La localización genitourinaria es la segunda en frecuencia tras la cabeza y cuello. El tratamiento suele ser médico, quedando la cirugía como coadyuvante, excepto en casos no controlados en que se precisan cirugías muy agresivas. El objetivo del estudio es analizar los casos de RMS de localización genitourinaria tratados en nuestro Centro y el papel que la cirugía tiene en su tratamiento. MATERIAL Y METODOS: Estudio retrospectivo de 20 pacientes (7 niñas y 13 niños) con una mediana de edad de 24 meses (rango de 1 mes a 12 años) con RMS del tracto urogenital tratados en nuestro Hospital desde 1990 hasta 2012. Se describen variables demográficas, localización del tumor primario, estadio al diagnóstico, tratamiento recibido, tanto médico como quirúrgico, con especial atención al tipo de cirugía realizada y seguimiento en términos de supervivencia. RESULTADOS: La localización del tumor primario fue: vejiga (6), paratesticular (5), vagina (3), retroperitoneo (3), pelvis menor (2) y próstata (1). Todos recibieron tratamiento médico con quimioterapia y radioterapia según protocolo de la Sociedad Internacional de Oncología Pediátrica (SIOP) previa biopsia diagnóstica. La cirugía, practicada en todos los casos como coadyuvante fue: reevaluación por biopsia (1), orquiectomía (5), resección tumoral (8) y cirugía radical (cistoprostatectomía o exanteración pélvica) en 6 pacientes. Hubo 3 fallecimientos, 2 por progresión de la enfermedad y 1 por sepsis postoperatoria. Los 17 restantes están vivos, lo que supone una supervivencia del 80% con una mediana de seguimiento de 14 años. CONCLUSIONES: El RMS es el tumor de tejidos blandos más frecuente en la infancia y la localización genitourinaria la segunda en frecuencia tras las parameníngeas. El tratamiento es multidisciplinar y la cirugía tiene un papel coadyuvante en casos de no respuesta al tratamiento médico o de tumor residual aunque hay pacientes que no responden al tratamiento médico y precisan de cirugía radical para su curación.

[Therapeutic approach in urinary tract stones in children]. / Abordaje de la litiasis en tracto urinario en niños.

PURPOSE: Kidney stone disease in children is a rare pathology, with a low incidence in Spain (1/4,500 hospitalized children). The spontaneous expulsion rate is about 34-47% which means that more of 50% of children need active treatment. Paediatric patients forming urinary stones have a high risk of recurrence, therefore, a standard diagnosis and treatment are needed. We present our experience in urolithiasis treatment in children. MATERIALS AND METHODS: We reviewed retrospectively all the patients ≤ 16 years hospitalized in our hospital with urolithiasis diagnosis from 2000 to 2013, citing treatment modality, stone-free rates and complications. RESULTS: A total of 69 patients with a mean age of 8,2 years (range 1-16 years) were treated in our hospital during that period. The main clinical presentation was pain (52%). The diagnosis was made by abdominal ultrasounds in all cases. About localization, 21 lithiasis were found in distal urether (UD), 8 in medium urether (UM), 3 in proximal urether (UP) and 13 in renal pelvis (PR). The mean size was 13 mm. 21 (30%) patients had a spontaneous expulsion of the stone, 14 (20%) patients were treated with extracorporeal shock wave lithotripsy and in 22 (32%) patients the elected therapy was ureterosopic stone fragmentation (n = 13) or removal (n = 9). No complications were observed. The overall stone-free rate was 79% (n = 55). CONCLUSIONS: Kidney stone disease in children is a rare pathology, with its own features about diagnosis and treatment, which requires medical care in a specialized center. The optimal treatment should be considered regarding the age of the patient, localization and size of the stone, as well as the team experience.

Analytical methodologies for the determination of cisplatin.

cis-Diamminedichloroplatinum(II) (cisplatin) is a important chemotherapeutic drug for cancer treatment since 1978. Unfortunately, because of the severe side-effects like nephrotoxicity, ototoxicity, etc., they are administered in small doses at low concentration establishing the maximum limit dosage to 100 mg/m(2) (21 days). A variety of analytical methods have been proposed for the determination of cisplatin in biological fluids and tissues that permit the accurate determination at or below the part per billion level in the native sample. The purpose of the current review is to provide a systematic survey of the latest analytical techniques for the determination of cisplatin in biological samples.

Recent advances in analytical determination of thalidomide and its metabolites.

Thalidomide, a racemate, is coming into clinical use as immuno-modulating and anti-inflammatory drug. Thalidomide was approved by the FDA in July 1998 for the treatment of erythema nodusum leprosum associated with leprosy. Recently, thalidomide is proving to be a promising drug in the treatment of a number of cancers and inflammatory diseases, such as multiple myeloma, inflammatory bowel disease (Crohn's disease), HIV and cancer associated cachexia. These effects may chiefly be exerted by S-thalidomide, but the enantiomers are inter-converted in vivo. Thalidomide is given orally, although parenteral administration would be desirable in some clinical situations. Thalidomide has been determined in formulations and, principally in biological fluids by a variety of methods such as high-performance liquid chromatography with ultraviolet detection and liquid chromatography coupled with tandem mass spectrometry. The overview includes the most relevant analytical methodologies used in its determination.

Influence of the transmission route and disease duration in the histopathology of chronic hepatitis C: a study of 101 patients.

OBJECTIVE: Different studies have demonstrated that factors such as transmission route, disease duration and age at the time of infection can influence the histological evolution of chronic hepatitis by the hepatitis C virus (HCV). The aim of this study was to determine if epidemiological factors such as disease duration and transmission route influence the severity of the histological lesions of patients with chronic hepatitis by HCV. DESIGN: A prospective study. METHODS: The hepatic biopsies of 101 patients diagnosed with chronic hepatitis by HCV were studied. The patients were divided into three groups according to transmission mode: (1) post-transfusional (n = 28), (2) associated with the use of drugs by parenteral route or intravenous drug use (n = 28), and (3) sporadic hepatitis (n = 45). RESULTS: We found more severe forms of hepatopathy in post-transfusional hepatitis and sporadic groups than in the intravenous drug user group of patients. The disease evolution time was significantly higher in patients diagnosed as having chronic active hepatitis with or without cirrhosis (13.8 +/- 9 years) than in patients with chronic persistent hepatitis (8 +/- 4 years), P < 0.01. We found a significant correlation between the evolution time of the infection by HCV and the Histology Activity Index (P < 0.01). The multivariate analysis showed that only the transmission route and the disease evolution time are predictive variables of Histology Activity Index in chronic hepatitis C. CONCLUSION: These results suggest that the post-transfusional and sporadic transmission routes and a greater evolution time of the disease are epidemiological variables that are associated with the presence of more severe histological lesions in chronic hepatitis C.

Simultaneous determination of iron, cobalt, nickel and copper by UV-visible spectrophotometry with multivariate calibration.

A method for the simultaneous spectrophotometric determination of the divalent ions of iron, cobalt, nickel and copper based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH) is proposed. The resolution of quaternary mixtures of these metallic ions was accomplished by several chemometric approaches. A comparative study of the results obtained for simultaneous determinations in mixture by using principal component regression (PCR) and partial least-squares regression (PLS-1 and PLS-2) for absorbance, first-derivative and second-derivative data is presented. In general, the best recovery values are obtained by the PLS-2 method for absorbance data. This procedure allows the simultaneous determination of the cited ions in alloys and biological materials Good reliability of the determination was proved.

Simultaneous spectrophotometric determination of cadmium, copper and zinc.

A method for the simultaneous spectrophotometric determination of cadmium, copper and zinc based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene)thiocarbonohydrazide is proposed. The absorption curves of these complexes overlap severely in the scanning range 380-480 nm. The analyte concentrations are calculated by a least squares fit of the pure spectra to the mixture spectra. A linear determination range of 0.1-1.7 mug/ml for cadmium, 0.1-1.3 mug/ml for copper and 0.2-1.2 mug/ml for zinc were obtained. The effect of interference was studied. The method has been applied to the determination of these metal ions in various type of materials.

Solvent extraction of cadmium as a previous step for its determination in biological samples by electrothermal atomization atomic absorption spectrometry.

A method is proposed for the solvent extraction of cadmium using 1,5-bis(di-2-pyridylmethylene)thiocarbohydrazide (DPTH) as extractant. The optimum extraction conditions were evaluated from a critical study of the effect of pH, concentration of extractant, shaking time and ionic strength. The maximum volume ratio of the aqueous to organic phase was 30:1 for a single-stage extraction of99-100% of the metal ion. The detection limit is 0.01 ng/ml cadmium, and the calibration is linear from 0.1 to 5 ng/ml. The relative standard deviation for 10 replicate measurements is 1.8% for 2 ng/ml cadmium. The extraction method was applied to the determination of cadmium in some biological materials using graphite furnace atomic absorption spectrometry.

Determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry after extraction with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide.

An inductively coupled plasma atomic emission spectrometric method for the determination of trace amounts of cadmium after extraction of the metal into isobutyl methyl ketone containing 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is described. The optimum extraction conditions were evaluated from a critical study of the effects of pH, concentration of extractant, shaking time and ionic strength. The detection limit for cadmium is 0.1 ng ml-1 and the calibration is linear from 0.2 to 140 ng ml-1. The relative standard deviation for ten replicate measurements is 2.9% for 2 ng ml-1 of cadmium. Results from the analysis of some certified biological reference materials are given.

Comparative inhibitory effects of dihydropyridines on platelet aggregation, calcium uptake and cyclic AMP concentration.

We studied the in vitro effects of several calcium channel blockers from the dihydropyridine (DHP) family on platelet aggregation and endogenous serotonin secretion, calcium uptake and cyclic AMP (cAMP) concentration using washed rat platelets. We found that, after 1 min incubation, nifedipine (Nif), nitrendipine (Nit) and nisoldipine (Nis) inhibited the thrombin-induced platelet aggregation and serotonin secretion with IC50 of about 140, 5 and 2 mumol/l, respectively. Nis and Nit are thus much more active than Nif. We also found that the thrombin-induced Ca2+ uptake amounted to 2,600 +/- 326 pmol Ca2+/10(9) platelets in control conditions. In the presence of 10 mumol/l of the DHP, this uptake was decreased by 19, 49 or 77%, with Nif, Nit or Nis, respectively. Compound BAY K 8644 (BK) with known agonistic properties on the calcium channel had inhibitory effects on the studied parameters. These compounds were in the order of Nif < BK < Nit < Nis. When added to previously aggregated platelets, Nit caused them to deaggregate. These results seem to be similar to those obtained with cAMP analogues or adenylate cyclase activators. The platelet resting cAMP concentration was therefore measured in the presence of the DHP. A nonsignificant increase was found with 20 mumol/l Nif whereas significant increases of 20 and 68% as compared with controls were obtained with 20 mumol/l Nit and Nis, respectively. Partition studies between platelets and plasma lipoproteins indicated that the effects might be related to the lipophilicity of the compounds. These data suggest that these agents work on platelet activity by multiple effects located intracellularly or at the membrane level.(ABSTRACT TRUNCATED AT 250 WORDS)