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D Carvalho

Publications and source records attributed to D Carvalho.

At least 19 recordsLinked to original sources
PubMed2003

Determination of amitraz in canine plasma by solid-phase microextraction-gas chromatography with thermionic specific detection.

A simple and rapid analytical method is presented for the determination of amitraz in canine plasma samples using solid-phase microextraction (SPME) and gas chromatography with thermionic specific detection (GC-TSD). The best conditions for the SPME procedure were: direct extraction on a polydimethlysiloxane (PDMS) fiber with 100-microm film thickness; 400 &microl of sample plasma matrix modified with 4 ml sodium borate solution (0.01 mol l(-1), pH 6.5); extraction temperature 70 degrees C, with stirring at 2500 rpm for 45 min. The method was linear between 20 and 400 ng ml(-1) with regression coefficients corresponding to 0.998 and coefficient of the variation of the points of the calibration curve lower than 15%. The lowest limit of quantification (LOQ) for amitraz in plasma was 20 ng ml(-1). This LOQ was determined as the lowest concentration on the calibration curve in which the coefficient of variation was lower than 15%. The proposed method was applied to determine amitraz concentrations in canine plasma to look for toxicity after treatment with amitraz in a dipping bath.

Animals↗
PubMed2002

Determination of lamotrigine simultaneously with carbamazepine, carbamazepine epoxide, phenytoin, phenobarbital, and primidone in human plasma by SPME-GC-TSD.

A simple and rapid analytical method is presented for the determination of lamotrigine simultaneously with primidone, carbamazepine, carbamazepine epoxide, phenobarbital, and phenytoin in human plasma using solid-phase microextraction (SPME) and gas chromatography with thermionic specific detection. The best conditions for the SPME procedure is established as following: direct extraction on a 65-microm Carbowax-divinylbenzene fiber; 1.0 mL of a sample plasma matrix modified with 15% NaCl and 3 mL of a potassium phosphate buffer (pH 7.0); extraction temperature at 30 degrees C; and stirring at a rate of 2500 rpm for 15 min. The method shows good linearity between 0.05 and 40.0 microg/mL with regression coefficients ranging between 0.9965 and 0.9995 and a coefficient of variation of the points of the calibration curve lower than 10%. The lowest limit of quantitation for the plasma-investigated drugs varies from 0.05 to 0.20 microg/mL, according to the drug. The proposed method is sensitive enough to work into subtherapeutic and therapeutic concentrations, being that it is applied in pharmacokinetic studies and patient routine therapeutic drug monitoring.

Anticonvulsants↗
PubMed2001

Comparison between solid-phase extraction methods for the chromatographic determination of organophosphorus pesticides in water.

A solid-phase microextraction (SPME) procedure has been developed to extract eight organophosphorus pesticides (OPs) in water and the method was compared with a conventional solid phase extraction (SPE) technique. The extracted OPs were analyzed by gas chromatography using thermionic specific detection. Both extraction methods presented linear calibration at least over the concentration range investigated (100 to 1000 ng x mL(-1) for SPE and 1 to 100 ng x mL(-1) for SPME). SPME method presented higher sensitivity than SPE. The quantitation limits were between 0.1 to 1.0 ng x mL(-1) for SPME depending upon the analyte, and 100 ng x mL(-1) for SPE. The precision, as measured by the standard deviations (RSD), were in the range 3.6% to 5.8% for SPME and 2.4% to 9.2% for SPE. Along with the feature of being a solvent - free sampling technique, SPME offers additional benefits due to its high sensitivity, simplicity, and small size sample required (typically: SPE - 500 mL, SPME - 5 mL).

Calibration↗
PubMed2000

An atypical presentation of Kawasaki disease resembling a retropharyngeal abscess.

Kawasaki disease is an acute systemic inflammatory disease, which occurs in children less than 10 years of age. The etiology of the disorder is unknown. Diagnosis is based upon clinician's recognition of a symptom pattern that includes high fevers, oral cavity changes, polymorphous rash, conjunctival injection, and cervical adenopathy. Most feared are the cardiac manifestations of Kawasaki syndrome, which result in an overall mortality rate of 2% in patients. Because of the common presenting symptoms, the otolaryngologist often plays a central role in early diagnosis of the disorder. The following case report describes a patient with Kawasaki disease whose initial presentation mimicked a retropharyngeal abscess. A literature review details the common and atypical early signs and symptoms of Kawasaki disease.

Child↗
PubMed1999

IgG anti-endothelial cell autoantibodies from patients with systemic lupus erythematosus or systemic vasculitis stimulate the release of two endothelial cell-derived mediators, which enhance adhesion molecule expression and leukocyte adhesion in an autocrine manner.

OBJECTIVE: To investigate the ability of anti-endothelial cell antibodies (AECA) to modulate endothelial cell function. METHODS: The effects of purified IgG from 11 patients with systemic lupus erythematosus (SLE) and 4 patients with systemic vasculitis on the expression of adhesion molecules (intercellular adhesion molecule 1, vascular cell adhesion molecule 1, E-selectin) by human umbilical vein endothelial cells and on the adhesion of the human promyelocytic cell line U937 were examined in vitro. RESULTS: IgG from 6 of 8 AECA-positive SLE patients and 3 of 3 AECA-positive systemic vasculitis patients up-regulated adhesion molecule expression and leukocyte adhesion to endothelial cells. The 4 AECA-negative samples had no effect. Transfer experiments demonstrated that at later time points (2-8 hours) after AECA addition, endothelium-derived interleukin-1 (IL-1) accounted for the ability of AECA to increase leukocyte adhesion. However, even within very short times after addition of AECA (<30 minutes), endothelial cells released a distinct transferable mediator with similar effects. CONCLUSION: AECA in patients with SLE or systemic vasculitis may contribute to pathogenesis by increasing leukocyte adhesion to endothelial cells. AECA act by inducing the release of at least two endothelium-derived mediators, one (as-yet-unidentified) rapidly and another (IL-1) more slowly, both of which stimulate endothelial cells in an autocrine manner.

Antibodies, Blocking↗
PubMed1999

Inefficiency of the anticoagulant therapy in the regression of the radiation-induced optic neuropathy in Cushing's disease.

Radiation-induced optic neuropathy is a rare complication (prevalence less than 1%) following radiotherapy of the sellar region. However, the vasculopathy in Cushing's disease predisposes to radiation-induced injury. We report the case of a 24-year-old man with Cushing's disease since he was 16. The hormonal study including bilateral inferior petrosal sinus catheterization diagnosed a pituitary right lesion, but imagiology was always negative. He underwent a transsphenoidal microadenomectomy and the pathological study showed the presence of corticotrophic hyperplasia but no adenoma. Secondary hypothyroidism and hypogonadism as well as permanent diabetes insipidus were diagnosed and because the patient was not cured he underwent a second transsphenoidal total hypophysectomy. After that and because he was still hypercortisolemic, pituitary external irradiation was given in a total dose of 6000 rad. Six months later he developed progressive bilateral visual loss. Cerebral MR revealed focal enhancement of the enlarged optic nerves and chiasm, associated with demyelination areas of the posterior visual pathways. Treatment was tried first with high doses of corticosteroids and later with anticoagulants-heparin EV. 1000 U/h during 7 days followed by warfarin, but unsuccessfully, probably because the patient was already amaurotic at the beginning of the last treatment.

Adolescent↗
PubMed1997

Influence of acetylator phenotype on the haematological and biochemical effects associated with dapsone in leprosy patients.

Methaemoglobinaemia and haemolytic anaemia were the principal side-effects observed in 30 leprosy patients undergoing long-term treatment with dapsone as a single drug or as part of multidrug therapy. Hepatic, pancreatic and renal evaluations showed no relevant clinical changes. Since N-acetylation is a major metabolic pathway for dapsone, slow acetylation phenotype may be a risk factor for the development of these reactions. To confirm this hypothesis we correlated acetylator phenotype and the haematological and biochemical effects induced by dapsone. No excess proportion of slow acetylators was found. We conclude that slow acetylators are not at greater risk of developing haematological side-effects of dapsone than fast acetylators.

Blood Cell Count↗
PubMed1996

IgG antiendothelial cell autoantibodies from scleroderma patients induce leukocyte adhesion to human vascular endothelial cells in vitro. Induction of adhesion molecule expression and involvement of endothelium-derived cytokines.

IgG autoantibodies that bind human endothelial cells (AECA) were detected by ELISA in 30 of 42 samples of sera from patients with scleroderma. Pretreatment of human umbilical vein endothelial cells with AECA-positive scleroderma sera, or IgG purified from these sera, led to a dose- and time-dependent increase in the ability of the cells to bind human U937 monocytic cells. Threshold-active IgG concentrations were 1-10 micrograms/ml; effects were significant after 3 h and maximal after 6-12 h. IgG from AECA-negative sera or normal sera were without effect. Increased adhesion of U937 cells was accompanied by increased expression of endothelial intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. Transfer of endothelial cell-conditioned media after pretreatment with AECA and immunodepletion of IgG demonstrated the presence of transferable activity that mimicked the effects of AECA. Treatment with neutralizing anticytokine antibodies indicated that IL-1, generated by the endothelial cells in response to AECA, was involved in the upregulation of adhesion molecules and U937 cell adhesion. We conclude that AECA can play a pathogenic role in scleroderma by activating endothelial cells, in part due to autocrine or paracrine actions of IL-1.

Antibodies, Blocking↗
PubMed1996

Raised anti-endothelial cell autoantibodies (AECA), but not anti-neutrophil cytoplasmic autoantibodies (ANCA), in recurrent oral ulceration: modulation of AECA binding by tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma).

Recurrent oral ulceration (ROU) is a common oral mucosal condition of unknown etiology. However, there is evidence to suggest that vasculitis may play a role. Here we investigate the presence in ROU of two autoantibodies associated with vasculitis, AECA and ANCA. AECA target as yet unidentified antigens on the endothelial cell surface and have been identified in patients with vasculitic disorders and inflammatory conditions with a vasculitic component. ANCA target specific neutrophil-associated proteins and are detected in specific vasculitic and chronic inflammatory disorders. AECA and ANCA levels were studied in 20 ROU patients and 20 controls. IgG AECA to the endothelial cell line ECV 304 were detected in 19 ROU patients and four controls. Levels were significantly raised in ROU both to ECV 304 (P < 0.000 05) and to human umbilical vein endothelial cells (HUVEC) (P < 0.005). Although levels were highest during episodes of ulceration, they were also raised between episodes. Stimulation of endothelial cells with TNF-alpha significantly increased AECA binding of both ROU (P < 0.005) and control samples (P < 0.0001), while IFN-gamma decreased binding (ROU P < 0.0001; controls P < 0.05). In contrast, ANCA were detected in only one patient and none of the controls. The presence of raised levels of AECA lends support to the hypothesis that a vasculitic process may underlie ROU. Moreover, these findings suggest that endothelial cell expression of AECA target antigens is increased by TNF-alpha and decreased by IFN-gamma stimulation.

Adolescent↗
PubMed1995

Thickening of the pituitary stalk: a finding suggestive of intrasellar tuberculoma? Case report.

We describe the case of a patient with an exclusively intrasellar mass, disclosed because of a left sixth nerve palsy and headaches. No other manifestation of disease, namely, endocrinological, was present. The lesion was approached transsphenoidally, and the pathological examination revealed a tuberculoma. Complete removal was achieved, and the patient started postoperative antituberculous therapy. In some circumstances, thickening of the infundibulum and the pituitary stalk could preoperatively suggest the diagnosis of hypophysial tuberculoma.

Antitubercular Agents↗
PubMed1989

Nuclear bodies in the normal and hyperfunctional human adrenal cortex.

Adrenal pieces obtained from six female patients, three without increased adrenocortical function and three with Cushing's disease, showed, in all adrenal cortex zones, cells containing simple and complex nuclear bodies. The simple nuclear bodies were spherical or ovoid and had a filamentous structure surrounded by a clear halo. Complex nuclear bodies were more numerous and heterogeneous in patients with adrenal pathology, and they were spherical with a proteinaceous filamentous capsule surrounding a core; the core was granular, filamentous or a mixture of granular and filamentous material, sometimes with a reticular or concentric arrangement. Some bodies showed vacuolar or multilocular aspect, and others had a close relationship with the nucleolus or appeared near the interchromatin granules. The meaning of adrenal nuclear bodies is discussed as well as their relationship with ACTH stimulation.

Adolescent↗
PubMedDate not supplied

Determination of albendazole metabolites in plasma by HPLC.

Albendazole is an antihelminthic agent belonging to the benzimidazole class and has been used successfully in the treatment of neurocysticercosis. We report here a method for the determination of the two major albendazole metabolites in plasma, albendazole sulfone and albendazole sulfoxide. The method consists of drug extraction from 500 microL of plasma previously acidified with chloroform-isopropanol (9:1, v/v) and extract purification with n-hexane immediately before chromatographic analysis. Separation of drugs and of the internal standard (mebendazole) was performed on an RP-18 column using acetonitrile-0.25N sodium acetate buffer (3:7, v/v), pH 5.0, as the mobile phase and using detection at 290 nm.

Adolescent↗
PubMedDate not supplied

An improved method for the simultaneous determination of mandelic and phenylglyoxylic acids by gas chromatography.

We present a method that permits the simultaneous analysis of mandelic acid (MA) and phenylglyoxylic acid (PGA) in the urine of workers occupationally exposed to styrene. The method consists of urine extraction in acid medium with chloroform and the subsequent formation of the respective methyl esters. The samples were submitted to gas chromatography using a glass column packed with 10% SP-1000. Recoveries of 66.7% and 95.4% were obtained for MA and PGA, respectively, with limits of quantitation of 0.03 g/L for MA and 0.02 g/L for PGA. The method proved to be precise in terms of both intra-assay and interassay analysis, with coefficients of variation less than 10%.

Chromatography, Gas↗
PubMedDate not supplied

A rapid, specific, and sensitive method for the determination of acetylation phenotype using dapsone.

An original, simple, specific, and rapid high-performance liquid chromatography assay for the determination of dapsone and monoacetyldapsone in human plasma is presented. The procedure consists of extracting the drugs and the internal standard (phenacetin) from 1 mL plasma with ethyl ether at alkaline pH. A liquid chromatograph equipped with a reversed-phase 5-microm C8 analytical column was used. The drugs were eluted with a mixture of water and methanol (70:30, v/v). Flow rate and wavelength were set at 1 mL/min and 286 nm, respectively. The precision, linearity, and limit of quantitation of the method were within acceptable limits. The method was considered adequate and has been used for the determination of the acetylator phenotype in population studies.

Acetylation↗