Endothelin-1 stimulates the Na+/Ca2+ exchanger reverse mode through intracellular Na+ (Na+i)-dependent and Na+i-independent pathways

This study aimed to explore the signaling pathways involved in the positive inotropic effect (PIE) of low doses of endothelin-1 (ET-1). Cat papillary muscles were used for force and intracellular Na(+) concentration (Na(+)(i)) measurements, and isolated cat ventricular myocytes for patch-clamp experiments. ET-1 (5 nmol/L) induced a PIE and an associated increase in Na(+)(i) that were abolished by Na(+)/H(+) exchanger (NHE) inhibition with HOE642. Reverse-mode Na(+)/Ca(2+) exchanger (NCX) blockade with KB-R7943 reversed the ET-1-induced PIE. These results suggest that the ET-1-induced PIE is totally attributable to the NHE-mediated Na(+)(i) increase. However, an additional direct stimulating effect of ET-1 on NCX after the necessary increase in Na(+)(i) could occur. Thus, the ET-1-induced increase in Na(+)(i) and contractility was compared with that induced by partial inhibition of the Na(+)/K(+) ATPase by lowering extracellular K(+) (K(+)(o)). For a given Na(+)(i), ET-1 induced a greater PIE than low K(+)(o). In the presence of HOE642 and after increasing contractility and Na(+)(i) by low K(+)(o), ET-1 induced an additional PIE that was reversed by KB-R7943 or the protein kinase C (PKC) inhibitor chelerythrine. ET-1 increased the NCX current and negatively shifted the NCX reversal potential (E(NCX)). HOE642 attenuated the increase in NCX outward current and abolished the E(NCX) shift. These results indicate that whereas the NHE-mediated ET-1-induced increase in Na(+)(i) seems to be mandatory to drive NCX in reverse and enhance contractility, Na(+)(i)-independent and PKC-dependent NCX stimulation appears to additionally contribute to the PIE. However, it is important to stress that the latter can only occur after the primary participation of the former.     

Primary hepatic lymphoma: an infrequent cause of focal hepatic lesion

Primary hepatic lymphoma (PHL) is confined to the liver with no evidence of extrahepatic lymphomatosis. Histopathologically, the PHL belongs to the group of non-Hodgkin's lymphomas and the most common subtype is the diffise large B-cell lymphoma. We present a 72-year-old woman, with no relevant antecedents and the following symptoms: early satiety, abdominal discomfort and rapid weight loss. Liver function tests are normal, erythrocyte sedimentation rate is accelerated and LDH progressively increases during the hospitalization. Imaging studies (ultrasound, CT scan, nuclear magnetic resonance) show a multilobued mass of around 12 cm of diameter in the right hepatic lobe. Tumoral and virological markers are negative. The pathology of an echo-guided biopsy informs a massive infiltration by a diffuse large B-cell lymphoma. The immunohistochemical study shows CD20+, CD45+ and negative CD3, CKAE1, AE3, Hepatocyte and HMB45. The citology of pleural liquid is negative for atypia, peripheral blood smear shows no signs of leukemia, bone marrow biopsy is negative for lymphomatous infiltration, and gallium scintigraphy and body CT scan do not reveal extrahepatic lesions. The patient starts chemotherapy with cyclophosphamide and methylprednisolone but worsens and dies two weeks after beginning treatment. We conclude that our patient had a rare disease with an unresectable lesion, poor prognostic factors and high recurrence risk. Chemotherapy is the treatment of choice in these cases.     

Effect of Flue Gases’ Corrosive Components on the Degradation Process of Evaporator Tubes

Corrosion of boiler tubes remains an operational and economic limitation in municipal waste power plants. The understanding of the nature, mechanism, and related factors can help reduce the degradation process caused by corrosion. The chlorine content in the fuel has a significant effect on the production of gaseous components (e.g., HCl) and condensed phases on the chloride base. This study aimed to analyze the effects of flue gases on the outer surface and saturated steam on the inner surface of the evaporator tube. The influence of gaseous chlorides and sulfates or their deposits on the course and intensity of corrosion was observed. The salt melts reacted with the steel surface facing the flue gas flow and increased the thickness of the oxide layer up to a maximum of 30 mm. On the surface not facing the flue gas flow, they disrupted the corrosive layer, reduced its adhesion, and exposed the metal surface. Beneath the massive deposits, a local overheating of the inner surface of the evaporator tubes occurred, which resulted in the release of the protective magnetite layer from the surface. Ash deposits reduce the boiler’s thermal efficiency because they act as a thermal resistor for heat transfer between the flue gases and the working medium in the pipes. The effect of insufficient feedwater treatment was evinced in the presence of mineral salts in the corrosion layer on the inner surface of the tube.     

Trypanosoma cruzi congenital transmission in wild bats

Trypanosoma cruzi congenital transmission in wild bats (Molossus molossus), associated with infected Rhodnius prolixus in a natural habitat from a rural locality in western Venezuela, is reported. T. cruzi blood circulating trypomastigotes in a pregnant bat were detected by parasitological methods. Polymerase chain reaction (PCR) assays carried out in samples from the heart and the fetus of the same infected female, revealed the presence of T. cruzi-specific DNA in both of the tissues, demonstrating transmission of the infection from the mother to the offspring. Eighty percent of the captured bats and 100% of the examined fetuses from pregnant specimens were shown to be infected by T. cruzi, indicating that M. molossus is a very susceptible species for this parasite, and that T. cruzi congenital transmission is a common phenomenon in nature. To our knowledge, this seems to be the first report on congenital T. cruzi transmission in wild bats in Venezuela. The circulation of T. cruzi lineage I in the study area was demonstrated by typing the isolates from bats and triatomine bugs captured in the same habitat. The potential epidemiological implication of these findings in areas where Chagas disease is endemic is discussed.     

Changes in the content of estrogen alpha and progesterone receptors during differentiation of mouse embryonic stem cells to dopamine neurons

Embryonic stem cells (ESC) can differentiate to derivatives of the three embryonic germ layers. Dopamine neurons have been produced from mouse and human ESC. This in vitro induction mimics the developmental program followed by dopaminergic cells in vivo. Production of dopamine neurons might have clinical applications for Parkinson's disease, which has a higher incidence in men than in women, suggesting a protective role for sex hormones, particularly progesterone and estradiol. These hormones exert many of their effects through the interaction with their nuclear receptors. In this study, we used a described 5-stage protocol for dopamine neuron differentiation of ESC, allowing neuronal commitment as evidenced by specific markers and by behavioural recovery of hemiparkinsonian rats after grafting. We studied the expression of steroid hormone receptors by immunoblot during this procedure and found an increase in the content of both A and B isoforms of progesterone receptor (PR) and a decrease in estrogen receptor alpha (ER-alpha) when cells were at the neural/neuronal stages, when compared with the amount found in initial pluripotent conditions. We also found the same pattern of PR and ER-alpha expression by immunocytochemistry. Ninety-two percent of dopamine neurons expressed progesterone receptors and only 19% of these neurons co-expressed tyrosine hydroxylase and ER-alpha. These results show a differential expression pattern of ER-alpha and PR isoforms during neuronal differentiation of ESC.     

Actinomyces meyeri cutaneous actinomycosis

Actinomyces meyeri cutaneous actinomycosis is a very rare disease. It often results from contiguous dissemination of an underlying focus. We report a case of pulmonary actinomicosis with secondary cutaneous involvement which led to the diagnosis.
A 51-year-old man presented with an indurated, erythematous plaque on his right chest wall. He had been diagnosed with pneumoniae one month prior ago and received antibiotic treatment but symptoms persisted. Fibrobroncoscopy was normal and bronchoalveolar lavage samples were negative. The cutaneous plaque evolved with fistulization and drainage of serohematic material with white grains. Actinomyces meyeri was cultured from bacteriologic samples. Ceftriaxone and doxiciclin were administered for a total of 12 months with complete resolution of the clinical condition.