A novel approach for lactose determination in cow's milk exploiting smartphone-based digital-image photometry.

Lactose, the main carbohydrate in cow's milk, may cause health problems for consumers with intolerance. Lactose determination in milk is hindered by the matrix complexity and lack of chromophore groups. Chromatography, volumetric, and spectrophotometric approaches involving chemical derivatization are time-consuming and require laborious sample preparation, which is incompatible with the high analytical demand. In this context, a novel approach is presented for lactose determination in milk exploiting smartphone-based digital-image photometry. It was based on a modification of the Benedict's method, involving formation of the violet Cu(I)/2,2'-biquinoline-4,4'-dicarboxylate (BCA) complex instead of the copper(I) oxide precipitate, aiming at improvement of sensitivity and precision. Sample pretreatment and analyte derivatization were performed in Eppendorf tubes with minimal reagent amounts and a smartphone camera was used for image acquisition under controlled conditions. Measurements were based on the RGB color system, taking channel G as the analytical response because of the complementarity with the color of the complex. Under the optimized conditions, the proposed procedure yielded a linear response up to 20 mg L-1 (r = 0.999), with a limit of detection of 1.5 mg L-1, which is compatible with determination of lactose in milk and dairy products categorized with low content of the sugar. The procedure takes less than 10 min, with a coefficient of variation of 3.0% (n = 12) and consumes as low as 160 µg Cu and 430 µg BCA per determination, thus being a more practical, fast, cost-effective, and environmental friendly analytical method.

Venous or arterial endothelium evaluation for early cardiovascular dysfunction in hypertensive patients?

Veins and arteries have active endothelium, producing vasoactive substances like nitric oxide. The aim of this study was to evaluate whether hypertensive patients exhibit venous endothelial dysfunction and to determine the relationship between endothelial-dependent and endothelial-independent vasodilation responses in venous and arterial systems. Sixteen unmedicated patients with stage I and II hypertension and without other risk factors and 15 matched normotensive volunteers had venous and arterial endothelial function evaluated with the dorsal hand vein technique and brachial artery ultrasonography. Hypertensive patients had a marked reduction of maximum dilation to acetylcholine (54.9% +/- 21.6%) compared with normotensive controls (85.2% +/- 27.0%). The flow-mediated dilation responses were reduced in hypertensive patients compared with controls (6.6% +/- 3.3%vs 12.4% +/- 2.6%, respectively). The responses to nitric oxide were similar in both groups, and the responses with the dorsal hand vein technique and flow-mediated dilation agreed in both groups. Hypertensive patients had an attenuated endothelial dependent response, indicating that endothelial dysfunction is also present in the venous system.

Influência das drogas antiarrítmicas nos limiares de desfibrilação em pacientes portadores de cardioversor-desfibrilador implantável / The influence of antiarrhytmic drugs at the onset of defibrilation in patients with implantable cardioverter-defibrilators

Atualmente os cardioversores desfibriladores implantáveis, em função de sua eficácia e segurança, tornaram se a primeira opção de tratamento na profilaxia secundária de morte súbita e, em algumas situações, na profilaxia primária. No entanto, o emprego desta prótese comumente está associado ao uso de drogas antiarrítmicas em pacientes de alto risco para morte súbita. Os antiarrítmicos frequentemente são julgados como responsáveis por alterações dos limiares de desfibrilação ventricular, especialmente a amiodarona. Portanto um conhecimento básico sobre a a interação entre estas drogas e limiares de desfibrilação é fundamental, no momento da seleção de um determinado agente.

Hemodynamic effects of a combination of bupropion and nicotine in anesthetized dogs.

Bupropion has been used to treat psychic depression and as a therapy for smoking cessation, the latter mainly in association with nicotine. However, there have been no detailed studies of the hemodynamic effects of the association of bupropion with nicotine during replacement therapy. In this study, we evaluated the effects of such an association on the cardiovascular parameters in anesthetized dogs. Bupropion, either alone or together with nicotine, had no significant effect on the cardiac index (CI; 4.7 +/- 0.2 vs 4.3 +/- 0.1 and 3.5 +/- 0.3 vs 3.4 +/- 0.3 L x min(-1) x m(2), respectively; mean +/- SEM) and mean arterial pressure (MAP; 134 +/- 5.0 vs 145 +/- 11.0 and 118 +/- 5.0 vs 133 +/- 10.5 mmHg, respectively). There was a slight but significant increase in the systemic vascular resistance index (SVRI; 2,165 +/- 93 vs 2,645 +/- 126 and 2,335 +/- 100 vs 2,737 +/- 200 dyn x cm(-5)m(-2), respectively). However, there was a significant increase in the mean pulmonary artery pressure (MPAP; 20 +/- 0.8 vs 25 +/- 1.6 and 18 +/- 1.3 vs 25 +/- 1.6 mmHg, respectively; p < 0.05) and pulmonary vascular resistance index (IRVP; 194 +/- 11 vs 272 +/- 21 and 206 +/- 32 vs 307 +/- 42 dyn x cm-5m(-2), respectively; p < 0.05). These results show that bupropion alone or in association with nicotine does not markedly affect most hemodynamic parameters of the systemic circulation, although the significant increase in MPAP and IRVP can elevate the pulmonary pressure.

Hemodynamic effects of bupropion in anesthetized dogs.

Bupropion is a non-nicotinic drug used in smoking cessation therapy. However, its acute effects remain unclear. In this study, we investigated the effects of bupropion on hemodynamic parameters in pentobarbital-anesthetized mongrel dogs. Bupropion administered either in bolus injections (3 or 6 mg/kg, i.v.) or in cumulative doses of 0.01, 0.1, 1, 3 and 10 mg/kg showed, in both studies, a significant increase of mean pulmonary arterial pressure and pulmonary vascular resistance index. These results show that bupropion can elevate the pulmonary pressure. Further investigations should be done to test this effect in smokers with chronic obstructive pulmonary disease.

[Prospective risk analysis in patients submitted to myocardial revascularization surgery]. / Análise prospectiva de risco em pacientes submetidos à cirurgia de revascularização miocárdica.

OBJECTIVE: To perform a stratified risk analysis in Myocardial Revascularization Surgery (MRS). METHODS: 814 patients were prospectively studied by applying two prognostic indexes (PI): Parsonnet and Modified Higgins. The Higgins PI was modified by substituting the variable "cardiac index value" by "low cardiac output syndrome" at the Intensive Care Unit (ICU) admission. The discriminatory capacity for morbimortality of both indexes was analyzed by ROC (receiver operating characteristic) curve. Logistic reaction identified the associated factors, independently from the events. RESULTS: Mortality and morbidity rates were 5.9% and 35.5%, respectively. The Modified Higgins PI, which analyzes pre- and intra-operative and physiological variables at the ICU admission showed areas under the ROC curve of 77% for mortality and 67% for morbidity. The Parsonnet PI, which only analyzes pre-operative variables, showed areas of 62.2% and 62.4%, respectively. Twelve variables were characterized as independent prognostic factors: age, diabetes mellitus, low body surface, creatinine levels (>1.5 mg/dL), hypoalbuminemia, non-elective surgery, prolonged time of extracorporeal circulation (ECC), necessity of post-ECC intra-aortic balloon, low cardiac output syndrome at the ICU admission, elevated cardiac frequency, decrease in serum bicarbonate concentrations and increase of the alveolar-arterial oxygen gradient within this period. CONCLUSION: The Modified Higgins PI showed to be superior to the Parsonnet PI at the surgical risk stratification, showing the importance of the analysis of intraoperative events and physiological variables at the patient's ICU admission, when prognostic definition is achieved.

Análise prospectiva de risco em pacientes submetidos à cirurgia de revascularização miocárdica / Prospective risk analysis in patients submitted to myocardial revascularization surgery

OBJETIVO: Análise estratificada de risco em Cirurgia de Revascularização Miocárdica (CRVM). MÉTODOS: Estudou-se, de forma prospectiva, 814 pacientes, aplicando-se dois índices prognósticos (IP): Parsonnet e Higgins Modificado. O IP Higgins foi Modificado por substituição da variável "valor do índice cardíaco" por "síndrome de baixo débito cardíaco", na admissão à Unidade de Terapia Intensiva (UTI). A capacidade discriminatória para morbimortalidade de ambos foi analisada através de curva ROC (receiver operating characteristic). Identificou-se, através de regressão logística, os fatores associados, de forma independente aos eventos. RESULTADOS: A taxa de mortalidade foi de 5,9 por cento e a de morbidade, 35,5 por cento. O IP Higgins Modificado, que analisa variáveis pré, intra-operatórias e variáveis fisiológicas na admissão à UTI, demonstrou áreas sob a curva ROC de 77 por cento para mortalidade e de 67 por cento, para morbidade. Por sua vez, o IP Parsonnet, que analisa somente variáveis pré-operatórias, demonstrou áreas de 62,2 por cento e 62,4 por cento, respectivamente. Doze variáveis caracterizaram-se como fatores prognósticos independentes: idade, diabete melito, baixa superfície corpórea, creatinina (>1,5 mg/dl), hipoalbuminemia, cirurgia não-eletiva, tempo prolongado de circulação extracorpórea (CEC), necessidade de balão intra-aórtico pós-CEC, síndrome de baixo débito cardíaco na admissão do paciente à UTI, freqüência cardíaca elevada, queda do bicarbonato sérico e alargamento do gradiente alvéolo-arterial de oxigênio nesse período. CONCLUSÃO: O IP Higgins Modificado mostrou-se superior ao IP Parsonnet na estratificação de risco cirúrgico, salientando a importância da análise de eventos intra-operatórios e variáveis fisiológicas na admissão do paciente à UTI, quando da definição prognóstica.