Noninvasive measurement of hydrogen and potassium ion flux from single cells and epithelial structures

This review introduces newdevelopments in a technique for measuring the movement of ions acrossthe plasma membrane. With the use of a self-referencing ion-selective(Seris) probe, transport mechanisms can be studied on a variety ofpreparations ranging from tissues to single cells. In this paper weillustrate this versatility with examples from the vas deferens andinner ear epithelium to large and small single cells represented bymouse single-cell embryos and rat microglia. Potassium and hydrogen ionfluxes are studied and pharmacological manipulation of the signals arereported. The strengths of the self-referencing technique are reviewedwith regard to biological applications, and the expansion ofself-referencing probes to include electrochemical and enzyme-based sensors is discussed.

     

Involvement of mitochondria in oxidative stress-induced cell death in mouse zygotes

Accumulation of reactive oxygen species during aging leads to programmed cell death (PCD) in many cell types but has not been explored in mammalian fertilized eggs, in which mitochondria are "immature," in contrast to "mature" mitochondria in somatic cells. We characterized PCD in mouse zygotes induced by either intensive (1 mM for 1.5 h) or mild (200 microM for 15 min) hydrogen peroxide (H(2)O(2)) treatment. Shortly after intensive treatment, zygotes displayed PCD, typified by cell shrinkage, cytochrome c release from mitochondria, and caspase activation, then terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining in condensed pronuclei. On the other hand, after mild treatment, zygotes arrested developmentally and showed neither cytochrome c release nor caspase activation over 48 h; until 72 h, 46% zygotes exhibited TUNEL staining, and 88% of zygotes lost plasma membrane integrity. Interestingly, mild oxidative treatment induced a decline in mitochondrial membrane potential and disruption of the mitochondrial matrix. Taken together, these results suggest that oxidative stress caused by H(2)O(2) induces PCD in mouse zygotes and that mitochondria are involved in the early phase of oxidative stress-induced PCD. Furthermore, mitochondrial malfunction also may contribute to cell cycle arrest, followed by cell death, triggered by mild oxidative stress.     

Initiation of flight in the unrestrained fly, Drosophila melanogaster

Neocalceostomoides brisbanensis sp. nov. from the gill arches, gill rakers and buccal lining of the blue catfish, Arius graeffei , is described. It is distinguished from the type species Neocalceostomoides arii (Unnithan, 1964) by the presence of a convoluted vas deferens with a blind-ending diverticulum; two lobes inside the vagina, each with ornamentation comprising rows of conical studs; two seminal receptacles and a post-testicular connection between the gut caeca. There is a closer resemblance to Neocalceostomoides spinivaginalis Lim, 1995, which also has vaginal lobes with ornamentations, but in N. spinivaginalis these ornamentations are elongated and spine-like and the penis tube and 'gubernaculum' are significantly longer. Neocalceostomoides brisbanensis was found on A. graeffei caught in Moreton Bay (sea water), Queensland, but not on catfish caught in the Brisbane River (fresh water). Some comments are made on the evolution and relationships of calceostomatines.     

Exposure to 900 MHz electromagnetic field induces an unbalance between pro-apoptotic and pro-survival signals in T-lymphoblastoid leukemia CCRF-CEM cells

It has been recently established that low-frequency electromagnetic field (EMFs) exposure induces biological changes and could be associated with increased incidence of cancer, while the issue remains unresolved as to whether high-frequency EMFs can have hazardous effect on health. Epidemiological studies on association between childhood cancers, particularly leukemia and brain cancer, and exposure to low- and high-frequency EMF suggested an etiological role of EMFs in inducing adverse health effects. To investigate whether exposure to high-frequency EMFs could affect in vitro cell survival, we cultured acute T-lymphoblastoid leukemia cells (CCRF-CEM) in the presence of unmodulated 900 MHz EMF, generated by a transverse electromagnetic (TEM) cell, at various exposure times. We evaluated the effects of high-frequency EMF on cell growth rate and apoptosis induction, by cell viability (MTT) test, FACS analysis and DNA ladder, and we investigated pro-apoptotic and pro-survival signaling pathways possibly involved as a function of exposure time by Western blot analysis. At short exposure times (2-12 h), unmodulated 900 MHz EMF induced DNA breaks and early activation of both p53-dependent and -independent apoptotic pathways while longer continuous exposure (24-48 h) determined silencing of pro-apoptotic signals and activation of genes involved in both intracellular (Bcl-2) and extracellular (Ras and Akt1) pro-survival signaling. Overall our results indicate that exposure to 900 MHz continuous wave, after inducing an early self-defense response triggered by DNA damage, could confer to the survivor CCRF-CEM cells a further advantage to survive and proliferate.     

Surveillance,health promotion and control of Chagas disease in the Amazon Region - Medical attention in the Brazilian Amazon Region: a proposal

We refer to Oswaldo Cruz''s reports dating from 1913 about the necessities of ahealthcare system for the Brazilian Amazon Region and about the journey of CarlosChagas to 27 locations in this region and the measures that would need to be adopted.We discuss the risks of endemicity of Chagas disease in the Amazon Region. Werecommend that epidemiological surveillance of Chagas disease in the Brazilian AmazonRegion and Pan-Amazon region should be implemented through continuous monitoring ofthe human population that lives in the area, their housing, the environment and thepresence of triatomines. The monitoring should be performed with periodicseroepidemiological surveys, semi-annual visits to homes by health agents and thetraining of malaria microscopists and healthcare technicians to identifyTrypanosoma cruzi from patients'' samples and T.cruzi infection rates among the triatomines caught. We recommend healthpromotion and control of Chagas disease through public health policies, especiallythrough sanitary education regarding the risk factors for Chagas disease. Finally, wepropose a healthcare system through base hospitals, intermediate-level units in theareas of the Brazilian Amazon Region and air transportation, considering thedistances to be covered for medical care.     

Cholinergic neurons and the cardiovascular response produced by central injection of substance P in the normotensive rat

The role of cholinergic neurons in central cardiovascular regulation is not well understood, however, activation of brain cholinergic neurons in several species evokes a hypertensive response. As with central cholinergic stimulation, intracerebroventricular (i.c.v.) injection of substance P (sP) elicits a pressor response in unanesthetized rats. The purpose of this study was to determine whether the cardiovascular effects following i.c.v. injection of this neuropeptide are mediated by central cholinergic neurons. Therefore, the cardiovascular response to sP was examined in control rats, and in animals pretreated centrally with classical pre- and post-synaptic cholinergic antagonists. Drugs were administered directly into the lateral ventricle while rats were freely-moving in their home cages. I.c.v. injection of sP produced a dose - dependent increase in arterial pressure and heart rate. The hypertensive response was significantly reduced by pretreatment with hemicholinium-3. This dose (20 ug) of hemicholinium-3 is capable of producing a maximal depletion of brain acetylcholine levels. The increase in heart rate to substance P was not as sensitive to hemicholinium-3 pretreatment as was blood pressure. Central pretreatment with the nicotinic receptor antagonist, hexamethonium was more effective than the muscarinic antagonist, atropine in blocking the pressor response to sP. Hexamethonium did not significantly alter the tachycardic response to the peptide, but atropine produced a small, but significant reduction in the response. Therefore, the pressor response to central injection of sP may be mediated to a large extent through cholinergic pathways involving nicotinic receptors.     

How to diagnose and manage Cushing's disease during pregnancy, when hypercortisolism is mild?

Diagnosis of mild Cushing's disease (CD) can be difficult in pregnant women, because its clinical and biochemical features can be erroneously interpreted as consequence of the gestation. Corticotropin releasing hormone (CRH) and desmopressin (DDAVP) tests are currently used to confirm CD, but data concerning adrenocorticotropic hormone (ACTH) response during pregnancy are lacking. A woman with mild cushingoid features was evaluated during the first trimester of gestation. Serum cortisol was normal at morning, but increased at midnight and incompletely suppressed by 1-mg dexamethasone overnight administration. Also 24-h urinary free cortisol levels were mildly elevated. She delivered vaginally a healthy newborn at the 39th week of an uneventful pregnancy. After delivery, an ACTH-secreting microadenoma was surgically removed. During the first trimester of gestation and after delivery, human CRH (h-CRH) and DDAVP-stimulated ACTH peaks were higher than those measured in 22 healthy premenopausal women. While the ACTH/h-CRH peak was intermediate between those measured in the healthy women and in 9 CD female patients, ACTH/DDAVP peak was in the range of CD patients and dramatically higher than those of healthy women. However, ACTH increase after h-CRH was significantly higher after delivery than during gestation (p?相似文献   

Mosaicism in von Hippel-Lindau disease: an event important to recognize

von Hippel-Lindau disease (VHL) is an autosomal dominant, familial neoplastic disorder with variable interfamilial and intrafamilial expression. VHL is characterized by pre-disposition to development of a combination of benign and malignant tumours affecting multiple organs. We provide molecular evidence of somatic mosaicism in nearly asymptomatic man whose daughter had VHL. The mosaic subject was found to have a cyst of the kidney and an angioma of the glans penis and had had surgery for a mandibular cyst and epididymal cystadenomas. Mosaicism could provide a genetic explanation for the clinical heterogeneity and variable severity of VHL. The real incidence of mosaicism is still unclear and the identification of mosaicism has important consequences in genetic counseling of VHL patients who appear to have de novo VHL mutations and should be considered when evaluating patients with isolated VHL-related tumours. Our results strongly suggest a complete and extensive clinical examination in the parents of each patient affected by an apparently de novo VHL germline mutation.We recommend performing a mutation screening of both parents of a proband with techniques that permit detection of low percentages of mosaicism before concluding that the proband has a de novo VHL mutation.