A multi-biomarker approach to lambda-cyhalothrin effects on the freshwater teleost matrinxa Brycon amazonicus: single-pulse exposure and recovery.

Effects of the pyrethroid lambda-cyhalothrin (LCH) were investigated in matrinxa Brycon amazonicus, a non-target freshwater teleost. The fish were submitted to a single-pulse exposure (10% of LC50; 96 h, 0.65 µg L-1), followed by 7 days of recovery in clean water. Hematologic parameters indicated impairments in oxygen transport, which were not recovered. Plasma [Na+], [Cl-], and protein were diminished, and only [Na+] remained low after recovery. Gill Na+/K+ATPase activity was increased and recovered to basal values. Brain acetylcholinesterase activity was not responsive to LCH. Liver ascorbic acid concentration was not altered, and reduced glutathione levels remained augmented even after recovery. LCH inhibited hepatic superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, while glutathione-S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH) activities were steady. After recovery, SOD remained low, and GPx was augmented. Liver depicted lipid peroxidation, which was not observed after recovery. Hepatic morphology was affected by LCH and was not completely recovered. These responses, combined with the persistence of changes even after recovery span, clearly show the feasibility of these biomarkers in evaluating LCH toxic potential to non-target organisms, highlighting the importance of pyrethroids' responsible use.

Membrane potential changes visualized in complete growth media through confocal laser scanning microscopy of bis-oxonol-loaded cells.

Confocal laser scanning microscopy (CLSM) was employed to visualize and measure membrane potential changes in several types of cultured adherent cells, such as human fibroblasts, mouse mammary tumor C127 cells, and human saphenous vein endothelial cells, preloaded with the anionic dye bis-1, 3,-diethylthiobarbituratetrimethineoxonol (bis-oxonol). The fluorescence of cell-associated bis-oxonol was detected in a single confocal plane. An original flow-chamber apparatus was employed to replace the extracellular medium, avoiding alterations of the plane selected for observation. In all the cell types and the experimental situations tested the intracellular distribution of the dye was typical; perinuclear zones accumulated the dye which, conversely, was excluded by the nucleus. Fluorescence was calibrated versus the membrane potential by varying the extracellular concentration of sodium in the presence of gramicidin. With this approach membrane potential was measured (i) in cultured human fibroblasts incubated under anisotonic conditions, (ii) in heterogeneous cell populations which respond unevenly to potential perturbing conditions, and (iii) in human macrovascular endothelial cells maintained in high-serum, complete growth medium. The results obtained indicate that CLSM can be successfully employed to measure changes of membrane potential in single, bis-oxonol-loaded adherent cells under experimental conditions which severely hinder conventional spectrofluorimetric approaches.

Emerging roles for sodium dependent amino acid transport in mesenchymal cells.

The functional aspects of sodium dependent amino acid transport in mesenchymal cells are the subject of this contribution. In a survey of the cross-talk existing among the various transport mechanisms, particular attention is devoted to the role played by substrates shared by several transport systems, such as L-glutamine. Intracellular levels of glutamine are determined by the activity of System A, the main transducer of ion gradients built on by Na,K-ATPase into neutral amino acid gradients. Changes in the activity of the System are employed to regulate intracellular amino acid pool and, hence, cell volume. System A activity has been found increased in hypertonically shrunken cells and in proliferating cells. Under both these conditions cells have to increase their volume; therefore, System A can be employed as a convenient mechanism to increase cell volume both under hypertonic and isotonic conditions. Although less well characterized, the uptake of anionic amino acids performed by System X(-) AG may be involved in the maintenance of intracellular amino acid pool under conditions of limited availability of neutral amino acids substrates of System A.

Response of human fibroblasts to hypertonic stress. Cell shrinkage is counteracted by an enhanced active transport of neutral amino acids.

Regulatory volume increase (RVI) has been studied in cultured human fibroblasts (CHF) incubated in a complete hypertonic growth medium (400 mosmol/kg). After the initial cell shrinkage induced by hypertonic treatment, cells recover their volume almost completely within 3 h. This RVI response is associated with a marked increase of the cell content of free amino acids. The cell content of potassium increases only slightly. Chromatographic analysis of the intracellular amino acid pool shows that the RVI-associated increase in cell amino acids is mainly a result of changes in the L-glutamine content. The intracellular accumulation of the analog 2-methylaminoisobutyric acid, a specific substrate of transport system A, is increased in CHF undergoing RVI. Hypertonic treatment causes an immediate and sustained cell hyperpolarization, as demonstrated by changes in the trans-membrane distribution ratio of L-arginine and in the fluorescence of the potential-sensitive dye bis-1,3-diethylthiobarbiturate-trimethineoxonol. Because of cell hyperpolarization, at the end of RVI the trans-membrane gradient of the sodium electrochemical potential is higher than that of the control. The increase in the extracellular potassium concentration ([K+]out = 40 mM) abolishes the hyperpolarization induced by hypertonic treatment and delays volume recovery. Cycloheximide suppresses RVI at a high but not at physiologic [K+]out. It is proposed that CHF counteract hypertonic shrinkage through an enhanced accumulation of substrates of transport system A sustained, initially, by an increase in the energy available for transport and, subsequently, also by the synthesis of new site A carriers.

Regulatory volume decrease of cultured human fibroblasts involves changes in intracellular amino-acid pool.

Regulatory volume decrease (RVD) has been studied in cultured human fibroblasts incubated in a complete growth medium at low osmolality (215 mosmolal). After the initial swelling induced by hypotonic treatment, cells recover their volume almost completely within about 60 min. This RVD is associated with comparable losses of cell potassium and amino acids. After an initial increase, cell content of sodium is kept at values close to control. Chromatographic analysis of intracellular amino-acid pool has shown that RVD-associated decrease in cell amino acids is due for the most part to changes in the intracellular concentration of L-glutamine. RVD-exerting cells undergo a rapid and marked depolarization that is maintained after cell volume recovery. This change in membrane potential has been detected with measurements of both the transmembrane distribution ratios of L-arginine and of fluorescence of potential-sensitive dye bis-oxonol. Due to depolarization, the trans-membrane gradient of sodium electrochemical potential is lowered. It is proposed that cell depolarization concurs to keep the intracellular concentration of amino acids low by inhibiting sodium-coupled uptake through system A.

Phorbol esters stimulate the transport of anionic amino acids in cultured human fibroblasts.

The effect of phorbol esters on the transport of amino acids has been evaluated in cultured human fibroblasts. The activity of the Na(+)-dependent system XAG- for anionic amino acids is selectively and markedly stimulated by phorbol esters. The effect is maximal within 15 min; it is attributable to an increase in transport maximum (Vmax) and not prevented by inhibitors of protein synthesis. The half-maximal stimulation is observed at concentrations of phorbol 12,13-dibutyrate lower than 100 nM. Prolonged incubations in the presence of 1 microM phorbol 12,13-dibutyrate lower the binding of the ligand to its receptor with a loss of the stimulatory effect on transport. The results presented indicate that the stimulation of amino acid transport through system XAG- by phorbol esters requires the activation of protein kinase C.

The transport of L-glutamine into cultured human fibroblasts.

The transport of L-glutamine has been studied in diploid human fibroblasts in culture. Mathematical discrimination by nonlinear regression, competition analysis, and conditions varying the relative contribution of the various mediations have been used to characterize the systems engaged in the inward transport of this amino acid. The adopted criteria showed that L-glutamine enters the fibroblast by the Na(+)-dependent systems ASC and A and by a Na(+)-independent route identified as system L. The relative contribution of these agencies to the total saturable uptake of glutamine varied with the concentration of the amino acid and with the nutritional state of the cell. At amino acid concentrations approaching those encountered in human plasma: (1) system ASC represented the primary mediation for entry of L-glutamine in human fibroblasts; (2) the contribution of system A was lower, though significant, in unstarved repressed cells and became predominant in starved derepressed cells; (3) the Na(+)-dependent system L accounted for less than one-fifth of glutamine uptake in either nutritional condition. The changes in the relative contribution of the various systems to the uptake of glutamine as a function of its concentration may have implications in pathophysiology under conditions associated with enhanced glutamine concentrations in the extracellular fluids.

Arrhythmogenic right ventricular dysplasia--clinical features.

The clinical features of the ARVD are variable. No one clinical feature is diagnostic. In this paper we will review commonly found features.

Coronary histology after percutaneous transluminal coronary angioplasty.

This article describes previously unreported histologic changes in the vessels of a patient who was admitted with an evolving myocardial infarction due to subtotal occlusion of the left anterior descending coronary artery. The patient died of cardiogenic shock 15 hours after undergoing a technically successful percutaneous transluminal coronary angioplasty procedure. Upon early postmortem study, histologic sections from the proximal, middle, and distal thirds of the left anterior descending coronary artery were polymorphic in appearance. Sections from the most proximal angioplasty site revealed intimal proliferation of polymorphonuclear leukocytes, as well as intimal fibrosis with plaque cleavage. Sections from the more distal angioplasty sites revealed plaque cleavage, intimal polymorphonuclear infiltration, and intimal, medial, and adventitial fracture with dissecting hemorrhage, although mural integrity had been maintained. Intense subintimal proliferation with inflammatory cells has previously been described only in an experimental animal model. Our case also appears to be the first in which adventitial disruption has been observed after percutaneous transluminal coronary angioplasty; this finding provides new evidence that an atherosclerotic coronary artery can tolerate vigorous dilatation without rupture.

Coronary artery spasm as a cause of chest pain in a patient with anomalous origin of the right coronary artery from the left sinus of valsalva.

The cause of chest pain in patients with anomalous origin of the right coronary artery from the left sinus of Valsalva has not yet been elucidated. In the following case, this anomaly was demonstrated, upon angiography, in a patient with recurrent chest pain and a negative stress test; in addition, spasm of the left anterior descending coronary artery was documented during ergonovine provocation. To our knowledge, this is the first time coronary artery spasm has been documented in a patient with this anomaly. On the basis of this case, we recommend ergonovine testing for all angina patients with aberrant coronary arteries in whom no other cause of chest pain is found at cardiac catheterization.

Inflammation of the coronary arteries in patients with unstable angina.

During surgery, 21 patients undergoing coronary artery bypass for unstable angina were found to have "red lines" overlying one or more coronary arteries. Adventitial biopsies showed vascular distention and inflammatory cells. The group was followed for an average of 54 months (14 to 68 months). There were no operative deaths. Recurrent myocardial ischemia developed in 38.1% (8/21); recurrent angina developed in 23.8% (5/21) and are being treated medically; myocardial infarction occurred in 9.5% (2/21); and reoperation was required in 4.8% (1/21). There was also one late death from a brain tumor. We suggest that the presence of adventitial inflammation may represent an aggressive, variant form of atherosclerosis and a less favorable clinical prognosis.

Carcinoid heart disease: a clinical pathologic, and therapeutic update.

The carcinoid syndrome is a rare clinical entity, the unique manifestations of which continue to excite the interest of physicians. Despite a common origin from neural crest tissue, the tumors are partially differentiated, as evidence by the different secretory products of foregut, midgut, and hindgut carcinoids. They also differ in their ability to metastasize, thus presenting an even more varied clinical picture. The prognosis of patients with carcinoid syndrome varies with the origin of the tumor and extent of metastases. The management of patients with carcinoid syndrome is difficult. Despite an understanding of the neurohormones that carcinoid tumors secrete, their various antagonists and inhibitors have been only partially successful in providing symptomatic relief. Carcinoid heart disease represents the most intriguing aspect of this syndrome. Although valvular dysfunction most often coexists with flushing and diarrhea, the findings of tricuspid regurgitation or stenosis occasionally provide the first clue to the presence of the disease. Despite intensive research, the definite etiology of these valvular lesions has not been established. A small group of patients has been managed by valve replacement. While surgical treatment has been successful in improving hemodynamics in most of these patients, it is expected to prolong life only in those without extensive liver metastases. In patients with extensive metastatic disease, one must carefully consider whether the risks and trauma of cardiac surgery for palliation are justified.