Viabilidade miocárdica na prática clínica / Assessing myocardial viability in clinical practice

Embora a avaliação da viabilidade miocárdica seja comum na prática do cardiologista, muitos médicos têm dúvidas a respeito dos resultados dos métodos diagnósticos. A medicina nuclear tem papel importante nos estudos de viabilidade, mas os laudos precisam ser interpretados num contexto clínico e fisiopatológico. Este artigo teve o objetivo de revisar a origem e a evolução do conceito da viabilidade miocárdica. São expostos os métodos diagnósticos com ênfase na medicina nuclear com uma explicação funcional sobre cada tipo de exame. A partir disso, são mostradas imagens como exemplos e é proposta uma maneira de atuar nesses casos baseada na clínica, na porcentagem de miocárdio acometido e na topografia das lesões coronarianas (proximais ou distais). (AU)

Although assessing myocardial viability is a common cardiology practice, many physicians question the results of diagnostic methods. Nuclear medicine plays an important role in viability studies, but the reports require interpretation in a clinical and pathophysiological context. this article was aimed at reviewing the origin and evolution of myocardial viability. Here we present diagnostic methods by emphasizing nuclear medicine and provide a functional explanation of each test type using example images. We also propose how to act in these cases based on clinic examination findings, the percentage of affected myocardium, and coronary lesion topography (proximal or distal).(AU)

Rubidium chloride modulated the fecal microbiota community in mice.

BACKGROUND: The microbiota plays an important role in host health. Although rubidium (Rb) has been used to study its effects on depression and cancers, the interaction between microbial commensals and Rb is still unexplored. To gain the knowledge of the relationship between Rb and microbes, 51 mice receiving RbCl-based treatment and 13 untreated mice were evaluated for their characteristics and bacterial microbiome changes. RESULTS: The 16S ribosomal RNA gene sequencing of fecal microbiota showed that RbCl generally maintained fecal microbial community diversity, while the shifts in fecal microbial composition were apparent after RbCl exposure. RbCl significantly enhanced the abundances of Rikenellaceae, Alistipes, Clostridium XlVa and sulfate-reducing bacteria including Deltaproteobacteria, Desulfovibrionales, Desulfovibrionaceae and Desulfovibrio, but significantly inhibited the abundances of Tenericutes, Mollicutes, Anaeroplasmatales, Anaeroplasmataceae and Anaeroplasma lineages. With regarding to the archaea, we only observed two less richness archaea Sulfolobus and Acidiplasma at the genus level. CONCLUSIONS: Changes of fecal microbes may in part contribute to the anticancer or anti-depressant effects of RbCl. These findings further validate that the microbiome could be a target for therapeutic intervention.

Evaluación del contenido de selenio en hojas de hierbas nativas de uso tradicional en la alimentación del guatemalteco / Evaluation of selenium content in leaves of native herbs of traditional food use in Guatemala

El selenio (Se) es un elemento esencial para el ser humano que se encuentra en pequeñas cantidades en los suelos, pero se acumula en ciertas plantas, proporcionando beneficios como antioxidante, antiinflamatorio y quemopreventivo por la presencia de unas 25 selenoproteínas que participan en diversas acciones de bienestar, lactancia, desarrollo, reproducción y salud de la progenie. El objetivo de este estudio fue evaluar el contenido de Se en hojas de vegetales utilizados tradicionalmente en la alimentación guatemalteca. Se colectaron hojas de materiales cultivados para los mercados locales de nueve hierbas nativas (Amaranthus hybridus, Cnidoscolus aconitifolius, Crotalaria longirostrata, Dysphania ambrosioides, Lycianthes synanthera, Sechium edule, Solanum americanum, Solanum nigrescens y Solanum wendlandii) y dos introducidas de reconocido uso alimenticio (Moringa oleifera y Spinacia oleracea), se secaron en un horno de convección forzada para lograr una humedad < 10% y se digirieron 0.25 ± 0.02 g de hojas en una mezcla de ácido nítrico y ácido perclórico que se calentó hasta la digestión total de la materia. El Se fue determinado por el método de reflexión total de rayos X, utilizando un estándar interno de itrio (Y) el que se midió utilizando reflectores de cuarzo en un espectrómetro de reflexión total de rayos X. De todas las especies evaluadas, únicamente A. hybridus demostró cantidades cuantificables de Se. Se determinó que 100 g de materia vegetal seca de A. hybridus proporciona 0.355 mg de Se, por lo que su consumo semanal puede contribuir con el requerimiento de este micronutriente para un adulto.

Selenium (Se) is an essential element for the human being; it is in small amounts in the soil but it accumulates in certain plants, providing benefits as antioxidant, anti-inflammatory and chemopreventive, due to the presence of about 25 selenoproteins that participate in different welfare and development actions, lactation, reproduction and health of the progeny. This study aimed to assess Se content in leaves of nine native plants traditionally used in Guatemalan food (Amaranthus hybridus, Cnidoscolus aconitifolius, Crotalaria longirostrata, Dysphania ambrosioides, Lycianthes synanthera, Sechium edule, Solanum americanum, Solanum nigrescens and Solanum wendlandii) and two internationally uses herbs (Moringa oleifera, Spinacia oleracea). Se was determined by total reflection X-ray method. Plants were dried in a forced convection oven to constant weight, then were digested by weighing 0.25 ± 0.02 g of dry plant material with a mixture of nitric and perchloric acid, and warmed to achieve complete digestion. Using a yttrium (Y) internal standard were measured using quartz reflectors Spectrometer Total reflection X-ray. Of all native plant species tested, only A. hybridus there were measurable amounts of Se. It was determined that 100 g of dry plant material of A. hybridus provides 0.355 mg of Se, so its weekly consumption by an adult might contribute to satisfied the requirement of this microelement.

Reduced Myocardial Flow in Heart Failure Patients With Preserved Ejection Fraction.

BACKGROUND: There remains limited insight into the pathophysiology and therapeutic advances directed at improving prognosis for patients with heart failure with preserved ejection fraction (HFpEF). Recent studies have suggested a role for coronary microvascular dysfunction in HFpEF. Rb-82 cardiac positron emission tomography imaging is a noninvasive, quantitative approach to measuring myocardial flow reserve (MFR), a surrogate marker for coronary vascular health. The aim of this study was to determine whether abnormalities exist in MFR in patients with HFpEF without epicardial coronary artery disease. METHODS AND RESULTS: A total of 376 patients with ejection fraction ≥50%, no known history of obstructive coronary artery disease, and a confirmed diagnosis of heart failure (n=78) were compared with patients with no evidence of heart failure (n=298), further stratified into those with (n=186) and without (n=112) hypertension. Global and regional left ventricular MFR was calculated as stress/rest myocardial blood flow using Rb-82 positron emission tomography. Patients with HFpEF were more likely to be older, female, and have comorbid hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, anemia, and renal dysfunction. HFpEF was associated with a significant reduction in global MFR (2.16±0.69 in HFpEF versus 2.54±0.80 in hypertensive controls; P<0.02 and 2.89±0.70 in normotensive controls; P<0.001). A diagnosis of HFpEF was associated with 2.62 times greater unadjusted odds of having low global MFR (defined as <2.0) and remained a significant predictor of reduced global MFR after adjusting for comorbidities. CONCLUSIONS: HFpEF, in the absence of known history for obstructive epicardial coronary artery disease, is associated with reduced MFR independent of other risk factors.

Laboratory evaluation of rubidium as a long-lasting marker for bloodfeeding sand flies (Diptera: Psychodidae).

The objective of this study was to evaluate the use of the trace element rubidium (Rb) as a long-lasting systemic biomarker for bloodfeeding females of the sand fly Phlebotomus papatasi Scopoli. Baits containing Rb chloride were found to be palatable to hamsters in this study. We were able to detect Rb using a portable X-ray fluorescence analyzer in all sand flies that fed on Rb-treated hamsters for at least 14 d postbloodmeal. We also detected Rb in sand flies that took a bloodmeal from hamsters up to 10 d after the hamsters were withdrawn from a Rb-treated diet. Results of this study constitute proof of concept for the incorporation of Rb chloride into rodent baits for marking bloodfeeding sand flies, and suggest that Rb marking could be used as a technique for evaluating rodent-targeted sand fly control methods and in ecological studies on sand flies.

The influence of a PHI-5-loaded silicone membrane, on cutaneous wound healing in vivo.

This study investigated whether a novel ionogenic substance, containing amongst others zinc and rubidium (PHI-5; Dermagenics Inc, Memphis, TN, USA), could improve the healing of full-thickness skin wounds. Uniform wounds were created on the right flank of guinea pigs. Micro-grooved silicone rubber membranes, containing 0 (controls), 1.25, 5.00, or 10.00 microg PHI-5, were sutured onto this wound. Standardized digital wound photographs were made after 1, 3, and 6 weeks. Also, wound biopsies were taken after 3 and 6 weeks for histological and histomorphometrical evaluation. For all study groups, 6 animals were used. Analysis of the 1-week digital photographs showed that the surface area of the wounds decreased significantly, with an increasing PHI-5 concentration. No other differences were found in the wound photographs. Also, no differences were measured in histomorphometry at 3 and 6 weeks. Concluding, in our study model a single application of PHI-5 did have a significant positive influence on initial wound healing.

MMP-2 assessment as an indicator of wound healing: A feasibility study.

OBJECTIVE: Evaluate the feasibility of assessment of fibroblast matrix metalloproteinase-2 (MMP-2) expression as an indicator of wound healing in wounds that change from chronically inert to actively healing. METHODS: Phase II feasibility study of 4 patients with nonhealing wounds (duration, > or = 3 months; surface area, > or = 1 cm). Wounds were treated with a dressing impregated with oak bark extract (DerMax) and evaluated weekly; biopsies were performed every 2 weeks until wound healing. RESULTS: Therapy-induced wound healing and immunohistochemical measurements of MMP-2 expression paralleled the clinical characteristics of wound healing. CONCLUSION: MMP-2 expression offers a reliable indicator for clinical wound healing induced by DerMax treatment.

Use of rubidium, manganese, and zinc as tracers to measure intestinal permeability by PIXE analysis: basal study in an experimental enteritis model.

Intestinal permeability has been suggested to be closely linked with the etiology or activity of Crohn's disease. However, current methods for measurement of intestinal permeability are too laborious for routine examination, as they require urine collection and/or use of radioisotopes. The present study was performed to develop a more convenient and safer method for assessing intestinal permeability using blood samples rather than urine. Rats with indomethacin-induced enteritis were orally administered Rb, Mn, and Zn as tracers. Intestinal permeability was determined by assaying the levels of Rb, Mn, and Zn in blood samples by particle-induced X-ray emission (PIXE). The distributions of Rb, Mn, and Zn in the small intestine after administration were analyzed by micro-PIXE. The conventional PIXE analysis showed that the levels of Rb and Zn in the blood in the enteritis group were correlated with the grade of enteritis. The micro-PIXE analysis showed that Rb, Mn, and Zn were translocated into the wall of the proximal small intestine 5 min after administration, and this effect was more conspicuous in the enteritis group than in controls. Analysis of blood or small intestine tissue samples using the PIXE allows determination of both intestinal permeability and the route of permeation.

Unique behavior of rubidium in mice under low oxygen atmosphere. Simultaneous tracing of Sc, Mn, Fe, Co, Zn, Se, Rb, Y, and Zr using off radioactive multitracer technique.

Relative tissue distributions of Sc, Mn, Fe, Co, Zn, Se, Rb, Y, and Zr tracers were studied in young mice housed under four different O2 atmospheres (10 percent, 20 percent, 80 percent, and 100 percent O2) using the radioactive multitracer technique developed at The Institute of Physical and Chemical Research (RIKEN). At 48 hr after injection of the multitracer, the tissue uptake rates were examined for 10 tissues (brain, cardiac muscle, lung, liver, spleen, pancreas, kidneys, skeletal muscle, bone, and blood) and expressed as the radioactivity percentage of the injected dose per gram of wet tissue (percent dose/g). Rubidium uptake rates for all soft tissues of mice housed under a 10 percent O2 atmosphere were found to be higher than those of the tissues of mice housed under the other three O2 atmospheres (20 percent, 80 percent, and 100 percent), but no difference was observed for the other elements (Sc, Mn, Fe, Co, Se, etc.) under any of the O2 atmospheres.

Inhibition by lithium and rubidium of gentamicin-induced release of N-acetyl-beta-D-glucosaminidase from perfused rat kidney.

N-acetyl-beta-D-glucosaminidase (NAG) is one of the sensitive hydrolytic lysosomal enzymes which is released after renal tubular damages. We studied gentamicin-induced nephrotoxicity by determining the NAG release in perfused rat kidney. 100 micrograms/ml of gentamicin caused a time-dependent increase in enzymuria, peaking at 90 min. At this time the released NAG is about sixfold more than the control. The effect of concurrent perfusion with 100 micrograms/ml gentamicin and with 0.5 mmol/l lithium chloride or 0.5 mmol/l rubidium chloride in the perfusion fluid was also studied by measuring NAG activity in the perfusate. Both cations decrease the gentamicin-induced NAG release. However, the inhibitory effect of lithium chloride may be due to interference of this ion with the polyphosphoinositide cycle in renal tubular lysosomal membranes. There is no obvious evidence for an inhibitory effect of rubidium chloride.

[The pharmacological action of rubidium chloride in depression]. / Azione del cloruro di rubidio nella depressione.

In the last few years antidepressant activity or Rubidium chloride has risen new interest. The drugs develops his action on dopaminergic stimulation reducing the depressive pattern. Fifteen depressed inpatients were studied for three weeks treated with Rubidium chloride (540 mg/day) and periodically monitored after hospitalization. Speed therapeutic efficacy has been shown, with lack of side effects. The results are discussed.

Effect of low dietary rubidium on plasma biochemical parameters and mineral levels in rats.

The effects of low dietary rubidium on plasma biochemical parameters and mineral levels in tissues in rats were studied. Eighteen male Wistar rats, weighing about 40 g, were divided into two groups and fed the diets with or without supplemental rubidium (0.54 vs 8.12 mg/kg diet) for 11 wk. Compared to the rats fed the diet with supplemental rubidium, the animals fed the diet without rubidium supplementation had higher urea nitrogen in plasma; lower rubidium concentration in tissues; lower sodium in muscle; higher potassium in plasma, kidney and tibia, and lower potassium in testis; lower phosphorus in heart and spleen; lower calcium in spleen; higher magnesium in muscle and tibia; higher iron in muscle; lower zinc in plasma and testis; and lower copper in heart, liver, and spleen, and higher copper in kidney. These results suggest that rubidium concentration in tissues reflects rubidium intake, and that rubidium depletion affects mineral (sodium, potassium, phosphorus, calcium, magnesium, iron, zinc, and copper) status.

Rubidium chloride fuses split circadian activity rhythms in hamsters housed in bright constant light.

Chronotypic effects of rubidium (Rb) were examined in hamsters whose circadian activity rhythms had split into two components while they were housed in bright constant light. Seven of 12 hamsters receiving RbCl in drinking water for 10 weeks showed fusing of the components into an intact rhythm compared with none of 7 control hamsters (p = 0.016). Rb may modify coupling between circadian oscillators via reduced photic input to the suprachiasmatic nuclei. Alternative mechanisms include changes in potassium metabolism or endocrine function or behavioral changes that in turn alter circadian function. This normalization of a circadian anomaly by a putative antidepressant suggests that Rb may be valuable in strengthening coupling between oscillators in cases of human chronopathology, including those implicated in the etiology of some affective disorders.

[Chronic administration of lithium and rubidium in rats. General behavior, explorative behavior and electric activity of the brain]. / Trattamento cronico con litio e rubidio del ratto. Comportamento generale, comportamento esplorativo e attività elettrica cerebrale.

We have studied the rat under chronic treatment with lithium carbonate and rubidium chloride both given ip. For a four week period we have recorded, once a week, weight, rectal temperature, tail-flick, motor co-ordination and general activity in a one-arm radial maze and in a Boissier-Simon table. At the end of the fourth week surface (SEEG) and deep EEGrams (DEEG: hippocampus, amygdala) were recorded from treated and control animals. FFT (Hanning window) was performed both for SEEG and DEEG. The findings are: 1) No changes in weight, rectal temperature, tail-flick and motor coordination (rotarod). 2) In the one-arm maze and in the Boissier-Simon table rubidium is in contrast to the effects of lithium, it causes increased activity and aggression 3) the EEGrams were analyzed by means of FFT as power in preselected bands of frequency. The results, on the whole, suggest, since these two ions have opposite effects on brain norepinephrine metabolism, that they may be useful in the treatment of PMD.

Memory storage and effect of repeated treatment with a new antidepressant drug: rubidium chloride.

Following 15 days' treatment with saline, 48 mg/kg rubidium chloride, 5 mg/kg imipramine hydrochloride, 10 mg/kg sodium phenobarbitone, 1000 mg/kg piracetam, or 0.20 mg/kg strychnine nitrate all administered intraperitoneally, mice were evaluated by habituation of exploratory activity using an open-field apparatus. In control animals a significant (P less than 0.05) decrease in open-field responses (ambulation, rearing and defaecation) was seen following a 1-day intersession interval and there was no retention of exploratory activity after a 5-day intersession interval. Administration of imipramine or phenobarbitone for 15 days was found to impair retention of memory after 1 day, whereas treatment with rubidium chloride, piracetam, or strychnine for 15 days improve retention after a 5-day intersession interval.

A pharmacokinetic analysis of long-term administration of rubidium chloride.

When a substance with a long biologic half-life is administered over an extended period with a varying dose schedule, many concerns about safety arise. In the case of rubidium chloride, which has been reported to have antidepressive activity, some of these concerns are related to the potential for unanticipated accumulation in the intracellular fluid, where replacement of more than 40% of the potassium ions is associated with toxicity in animals. A pharmacokinetic model of rubidium distribution, based on a three-compartment system, is in accord with the empirical data from previous human trials. By comparison of predicted with observed plasma rubidium levels, a sudden change in the ratio of intra- to extracellular distribution of rubidium can be detected, and availability of this warning signal of potentially toxic intracellular accumulation can be useful during extended administration.

Measurement of cation transport in vivo in healthy volunteers after the oral administration of lithium carbonate.

1. We have measured cation transport in vivo in seven healthy volunteers under control conditions and after they had taken lithium carbonate for 21 days in doses which maintained the serum lithium concentration in the range 0.6-0.8 mmol/l. 2. We have measured cation transport in vivo after the administration of an oral load of rubidium chloride, and have found that, although intra-erythrocytic concentrations of rubidium were significantly lower 1 h after the administration of rubidium when the subjects were taking lithium, there was a significant increase in the rate of uptake of rubidium into the erythrocytes over the subsequent period of the test, suggesting a direct stimulation of sodium, potassium-activated adenosine triphosphatase by lithium. 3. Lithium administration did not affect the plasma concentration versus time profile of rubidium after the rubidium load, implying that the lithium-stimulated uptake of rubidium which occurs in erythrocytes does not necessarily occur in other cell types. 4. These results suggest that previous studies of cation transport using peripheral cells and assay systems in vitro do not necessarily reflect changes in cation transport in vivo in excitable tissues.