Estudio morfométrico de pezuñas en genotipos bovinos criados en los humedales del Ñeembucú Paraguay

Se evaluó la morfometría de pezuñas en bovinos criados en los humedales del Ñeembucú y áreas de influencia. Participaron 80 hembras adultas agrupadas por genotipos en Criollo Ñeembucú; Criollo Pilcomayo; Nelore; Brahman y Brangus, analizándose Longitud muralla (LM); Altura pezuña (AP); Longitud talón (LT); Longitud pezuña (LP); Diagonal pezuña (DP); Grosor pezuña (GP). El análisis con el software R incluyó varianza paramétrica y no paramétrica, y en las pezuñas anterior medial y posterior lateral, Análisis de Componentes Principales, Discriminante Canónico y Clúster por el método de Ward. El Criollo Ñeembucú mostró mayores LM y AP, el Nelore las menores; la LT, reveló estabilidad longitudinal en nativos, no así en el Nelore. La LP fue mayor en Criollos, Nelore y Brangus. La DP mostró adecuado reparto de las cargas. El GP, mayor en el Nelore y Brangus, fue menor en el Brahman, con talones bajos y menores DP y LP. El ACP explicó más del 70% de la variación. El CP1 se asoció positivamente a DP, LP, LM, LT y AP; el CP2 fue vinculado a GP. El ADC explicó mejor la variabilidad entre genotipos, con valores elevados de GP en el Nelore y bajos en el Brahman. El método de Ward conformó grupos con la mayoría de los genotipos, revelando poca diferencia entre individuos; no obstante, algunos clústeres concentraron en grupos diferentes a la mayoría de los animales Nelore y Brahman.

Urban vegetation and particle air pollution: Experimental campaigns in a traffic hotspot

This work presents the main results of two experimental campaigns carried out in summer and winter seasons in a complex pollution hotspot near a large park, El Retiro, in Madrid (Spain). These campaigns were aimed at understanding the microscale spatio-temporal variation of ambient concentration levels in areas with high pollution values to obtain data to validate models on the effect of urban trees on particulate matter concentrations. Two different measuring approaches have been used. The first one was static, with instruments continuously characterizing the meteorological variables and the particulate matter concentration outside and inside the park. During the summer campaign, the particulate matter concentration was clearly influenced by a Saharan dust outbreak during the period 23 June to 10 July 2016, when most of the particulate matter was in the fraction PM_2.5-10. During the winter campaign, the mass concentrations were related to the meteorological conditions and the high atmospheric stability. The second approach was a dynamic case with mobile measurements by portable instruments. During the summer campaign, a DustTrak instrument was used to measure PM₁₀ and PM_2.5 in different transects close to and inside the park at different distances from the traffic lane. It was observed a decrease in the concentrations up to 25% at 20 m and 50% at 200 m. High PM₁₀ values were linked to dust resuspension caused by recreational activities and to a Saharan dust outbreak. The highest PM values were measured at the Independencia square, an area with many bus stops and high traffic density. During the winter campaign, three microaethalometers were used for Black Carbon measurement. Both pollutants also showed a reduction in their concentrations when moving towards inside the park. For PM₁₀ and PM_2.5, reductions up to 50% were observed, while for BC this reduction was smaller, about 20%.

The Calcium-Sensing Receptor in Health and Disease

The extracellular calcium-sensing receptor (CaSR) is a unique G protein-coupled receptor (GPCR) activated by extracellular Ca²⁺ and by other physiological cations including Mg²⁺, amino acids, and polyamines. CaSR is the most important master controller of the extracellular Ca²⁺ homeostatic system being expressed at high levels in the parathyroid gland, kidney, gut and bone, where it regulates parathyroid hormone (PTH) secretion, vitamin D synthesis, and Ca²⁺ absorption and resorption, respectively. Gain and loss of function mutations in the CaSR are responsible for severe disturbances in extracellular Ca²⁺ metabolism. CaSR agonists (calcimimetics) and antagonists (calcilytics) are in use or under intense research for treatment of hyperparathyroidism secondary to kidney failure and hypocalcemia with hypercalciuria, respectively. Expression of the CaSR extends to other tissues and systems beyond the extracellular Ca²⁺ homeostatic system including the cardiovascular system, the airways, and the nervous system where it may play physiological functions yet to be fully understood. As a consequence, CaSR has been recently involved in different pathologies including uncontrolled blood pressure, vascular calcification, asthma, and Alzheimer's disease. Finally, the CaSR has been shown to play a critical role in cancer either contributing to bone metastasis and/or acting as a tumor suppressor in some forms of cancer (parathyroid cancer, colon cancer, and neuroblastoma) and as oncogene in others (breast and prostate cancers). Here we review the role of CaSR in health and disease in calciotropic tissues and others beyond the extracellular calcium homeostatic system.

A dose-volume histogram based decision-support system for dosimetric comparison of radiotherapy treatment plans

Background

The choice of any radiotherapy treatment plan is usually made after the evaluation of a few preliminary isodose distributions obtained from different beam configurations. Despite considerable advances in planning techniques, such final decision remains a challenging task that would greatly benefit from efficient and reliable assessment tools.

Methods

For any dosimetric plan considered, data on dose-volume histograms supplied by treatment planning systems are used to provide estimates on planning target coverage as well as on sparing of organs at risk and the remaining healthy tissue. These partial metrics are then combined into a dose distribution index (DDI), which provides a unified, easy-to-read score for each competing radiotherapy plan. To assess the performance of the proposed scoring system, DDI figures for fifty brain cancer patients were retrospectively evaluated. Patients were divided in three groups depending on tumor location and malignancy. For each patient, three tentative plans were designed and recorded during planning, one of which was eventually selected for treatment. We thus were able to compare the plans with better DDI scores and those actually delivered.

Results

When planning target coverage and organs at risk sparing are considered as equally important, the tentative plan with the highest DDI score is shown to coincide with that actually delivered in 32 of the 50 patients considered. In 15 (respectively 3) of the remaining 18 cases, the plan with highest DDI value still coincides with that actually selected, provided that organs at risk sparing is given higher priority (respectively, lower priority) than target coverage.

Conclusions

DDI provides a straightforward and non-subjective tool for dosimetric comparison of tentative radiotherapy plans. In particular, DDI readily quantifies differences among competing plans with similar-looking dose-volume histograms and can be easily implemented for any tumor type and localization, irrespective of the planning system and irradiation technique considered. Moreover, DDI permits to estimate the dosimetry impact of different priorities being assigned to sparing of organs at risk or to better target coverage.

Treatment of Alzheimer disease using combination therapy with plasma exchange and haemapheresis with albumin and intravenous immunoglobulin: Rationale and treatment approach of the AMBAR (Alzheimer Management By Albumin Replacement) study

INTRODUCTION

There is a growing interest in new therapeutic strategies for the treatment of Alzheimer disease (AD) which focus on reducing the beta-amyloid peptide (Aβ) burden in the brain by sequestering plasma Aβ, a large proportion of which is bound to albumin and other proteins. This review discusses the concepts of interaction between Aβ and albumin that have given rise to AMBAR (Alzheimer's Disease Management by Albumin Replacement) project, a new multicentre, randomised, controlled clinical trial for the treatment of AD.

DEVELOPMENT

Results from preliminary research suggest that Albutein(®) (therapeutic albumin, Grifols) contains no quantifiable levels of Aβ. Studies also show that Albutein(®) has Aβ binding capacity. On the other hand, AD entails a high level of nitro-oxidative stress associated with fibrillar aggregates of Aβ that can induce albumin modification, thus affecting its biological functions. Results from the phase ii study confirm that using therapeutic apheresis to replace endogenous albumin with Albutein(®) 5% is feasible and safe in patients with AD. This process resulted in mobilisation of Aβ and cognitive improvement in treated patients. The AMBAR study will test combination therapy with therapeutic apheresis and haemopheresis with the possible leverage effect of Albutein(®) with intravenous immunoglobulin replacement (Flebogamma(®) DIF). Cognitive, functional, and behavioural changes in patients with mild to moderate AD will be assessed.

CONCLUSIONS

the AMBAR study represents a new therapeutic perspective for AD.

[Target volume segmentation of PET images by an iterative method based on threshold value]

OBJECTIVES

An automatic segmentation method is presented for PET images based on an iterative approximation by threshold value that includes the influence of both lesion size and background present during the acquisition.

MATERIAL AND METHODS

Optimal threshold values that represent a correct segmentation of volumes were determined based on a PET phantom study that contained different sizes spheres and different known radiation environments. These optimal values were normalized to background and adjusted by regression techniques to a two-variable function: lesion volume and signal-to-background ratio (SBR). This adjustment function was used to build an iterative segmentation method and then, based in this mention, a procedure of automatic delineation was proposed. This procedure was validated on phantom images and its viability was confirmed by retrospectively applying it on two oncology patients.

RESULTS

The resulting adjustment function obtained had a linear dependence with the SBR and was inversely proportional and negative with the volume. During the validation of the proposed method, it was found that the volume deviations respect to its real value and CT volume were below 10% and 9%, respectively, except for lesions with a volume below 0.6 ml.

CONCLUSIONS

The automatic segmentation method proposed can be applied in clinical practice to tumor radiotherapy treatment planning in a simple and reliable way with a precision close to the resolution of PET images.

Selecting radiotherapy dose distributions by means of constrained optimization problems

The main steps in planning radiotherapy consist in selecting for any patient diagnosed with a solid tumor (i) a prescribed radiation dose on the tumor, (ii) bounds on the radiation side effects on nearby organs at risk and (iii) a fractionation scheme specifying the number and frequency of therapeutic sessions during treatment. The goal of any radiotherapy treatment is to deliver on the tumor a radiation dose as close as possible to that selected in (i), while at the same time conforming to the constraints prescribed in (ii). To this day, considerable uncertainties remain concerning the best manner in which such issues should be addressed. In particular, the choice of a prescription radiation dose is mostly based on clinical experience accumulated on the particular type of tumor considered, without any direct reference to quantitative radiobiological assessment. Interestingly, mathematical models for the effect of radiation on biological matter have existed for quite some time, and are widely acknowledged by clinicians. However, the difficulty to obtain accurate in vivo measurements of the radiobiological parameters involved has severely restricted their direct application in current clinical practice.In this work, we first propose a mathematical model to select radiation dose distributions as solutions (minimizers) of suitable variational problems, under the assumption that key radiobiological parameters for tumors and organs at risk involved are known. Second, by analyzing the dependence of such solutions on the parameters involved, we then discuss the manner in which the use of those minimizers can improve current decision-making processes to select clinical dosimetries when (as is generally the case) only partial information on model radiosensitivity parameters is available. A comparison of the proposed radiation dose distributions with those actually delivered in a number of clinical cases strongly suggests that solutions of our mathematical model can be instrumental in deriving good quality tests to select radiotherapy treatment plans in rather general situations.

Evaluation of the potential of indigenous calcareous shale for neutralization and removal of arsenic and heavy metals from acid mine drainage in the Taxco mining area, Mexico

In the Taxco mining area, sulfide mineral oxidation from inactive tailings impoundments and abandoned underground mines has produced acid mine drainage (AMD; pH 2.2-2.9) enriched in dissolved concentrations (mg l⁻¹) sulfate, heavy metals, and arsenic (As): SO₄²⁻ (pH 1470-5454), zinc (Zn; 3.0-859), iron (Fe; pH 5.5-504), copper (Cu; pH 0.7-16.3), cadmium (Cd; pH 0.3-6.7), lead (Pb; pH < 0.05-1.8), and As (pH < 0.002-0.6). Passive-treatment systems using limestone have been widely used to remediate AMD in many parts of the world. In limestone-treatment systems, calcite simultaneously plays the role of neutralizing and precipitating agent. However, the acid-neutralizing potential of limestone decreases when surfaces of the calcite particles become less reactive as they are progressively coated by metal precipitates. This study constitutes first-stage development of passive-treatment systems for treating AMD in the Taxco mine area using indigenous calcareous shale. This geologic material consists of a mixture of calcite, quartz, muscovite, albite, and montmorillonite. Results of batch leaching test indicate that calcareous shale significantly increased the pH (to values of 6.6-7.4) and decreased heavy metal and As concentrations in treated mine leachates. Calcareous shale had maximum removal efficiency (100%) for As, Pb, Cu, and Fe. The most mobile metals ions were Cd and Zn, and their average percentage removal was 87% and 89%, respectively. In this natural system (calcareous shale), calcite provides a source of alkalinity, whereas the surfaces of quartz and aluminosilicate minerals possibly serve as a preferred locus of deposition for metals, resulting in the neutralizing agent (calcite) beings less rapidly coated with the precipitating metals and therefore able to continue its neutralizing function for a longer time.

The next generation of burns treatment: intelligent films and matrix, controlled enzymatic debridement, and adult stem cells

We describe a novel technology based on nanoengineered multifunctional acellular biologic scaffolds combined with wound dressings and films of the same kind. This method allows selective delivery and release of shielded biomaterials and bioactive substances to a desired wound or damaged tissue while stimulating the selective anchoring and adhesion of endogenous circulating repairing cells, such as mesenchymal stem cells, to obtain a faster and more physiologic healing process. We also present a new controlled enzymatic debridement process for more effective burned tissue scarolysis. In light of our preliminary in vitro and in vivo data, we are convinced that these approaches can include the use of other kinds of adult stem cells, such as endometrial regenerative cells, to improve the vascularization of the constructs, with great potential in the entire tissue and organ regeneration field but especially for the treatment of severely burned patients, changing the way these lesions may be treated in the future.

Circulating endothelial progenitor cells and erectile dysfunction: possibility of nutritional intervention?

To provide an overview of molecular and cellular processes involved in erectile dysfunction (ED) with emphasis on circulating endothelial progenitor cells (EPC) and discuss possible nutraceutical means of intervention. A review of literature on Pubmed related to EPC and ED was conducted. Patients with ED appear to possess a reduced number of circulating EPC, which is associated with poor endothelial function possibly as a result of underlying low-grade inflammation. Several studies support the possibility of improving erectile function by inhibition of inflammation as well as administration of various stem cell types. One particularly interesting approach is nutraceutical supplementation to increase circulating EPC, as demonstrated in the product Stem-Kine. Interventions aimed at increasing circulating EPC may have potential in treatment of vascular ED.

Effects of MiRP1 and DPP6 beta-subunits on the blockade induced by flecainide of Kv4.3/KChIP2 channels

BACKGROUND AND PURPOSE

The human cardiac transient outward potassium current (Ito) is believed to be composed of the pore-forming Kv4.3 alpha-subunit, coassembled with modulatory beta-subunits as KChIP2, MiRP1 and DPP6 proteins. beta-Subunits can alter the pharmacological response of Ito; therefore, we analysed the effects of flecainide on Kv4.3/KChIP2 channels coassembled with MiRP1 and/or DPP6 beta-subunits.

EXPERIMENTAL APPROACH

Currents were recorded in Chinese hamster ovary cells stably expressing K(V)4.3/KChIP2 channels, and transiently transfected with either MiRP1, DPP6 or both, using the whole-cell patch-clamp technique.

KEY RESULTS

In control conditions, Kv4.3/KChIP2/MiRP1 channels exhibited the slowest activation and inactivation kinetics and showed an 'overshoot' in the time course of recovery from inactivation. The midpoint values (Vh) of the activation and inactivation curves for Kv4.3/KChIP2/DPP6 and Kv4.3/KChIP2/MiRP1/DPP6 channels were approximately 10 mV more negative than Vh values for Kv4.3/KChIP2 and Kv4.3/KChIP2/MiRP1 channels. Flecainide (0.1-100 microM) produced a similar concentration-dependent blockade of total integrated current flow (IC50 approximately 10 microM) in all the channel complexes. However, the IC50 values for peak current amplitude and inactivated channel block were significantly different. Flecainide shifted the Vh values of both the activation and inactivation curves to more negative potentials and apparently accelerated inactivation kinetics in all channels. Moreover, flecainide slowed recovery from inactivation in all the channel complexes and suppressed the 'overshoot' in Kv4.3/KChIP2/MiRP1 channels.

CONCLUSIONS AND IMPLICATIONS

Flecainide directly binds to the Kv4.3 alpha-subunit when the channels are in the open and inactivated state and the presence of the beta-subunits modulates the blockade by altering the gating function.

Determination of nonylphenol and nonylphenol ethoxylates in environmental solid samples by ultrasonic-assisted extraction and high performance liquid chromatography-fluorescence detection

A simple and rapid analytical method for the determination of nonylphenol (NP) and nonylphenol ethoxylates (NPEOx) in solid environmental samples has been developed. This method combines an ultrasonic-assisted extraction procedure in small columns and an enrichment step onto C(18) solid-phase extraction cartridges prior to separation using HPLC with fluorescence detection. Method optimization was carried out using soil samples fortified at different concentration levels (from 0.1 to 100 microg/g). Under optimum conditions, 2g of soil was placed in small glass columns and extraction was performed assisted by sonication (SAESC) at 45 degrees C in two consecutive steps of 15 min using a mixture of H(2)O/MeOH (30/70). The obtained extracts were collected, loaded onto 500 mg C(18) cartridges, and analytes were eluted with 3 x 1 ml of methanol and 1 ml of acetonitrile. Finally, sample extracts were evaporated under a nitrogen stream, redissolved in 500 microl H(2)O/AcN (50/50), and passed though a 0.45 microm nylon filter before final determination by HPLC-FL. The developed procedure allowed to achieve quantitative recoveries for NP and NPEOx, and was properly validated. Finally, the method was applied to the determination of these compounds in soils and other environmental solid samples such as sediments, compost and sludge.

Effects of atorvastatin and simvastatin on atrial plateau currents

Recent evidence has shown that the inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins) might exert antiarrhythmic effects both in experimental models and in humans. In this study we analyzed the effects of atorvastatin and simvastatin acid (SVA) on the currents responsible for the duration of the plateau of human atrial action potentials: hKv1.5, Kv4.3, and L-type Ca(2+) (I(Ca,L)). hKv1.5 and Kv4.3 currents were recorded in transfected Ltk(-) and Chinese hamster ovary cells, respectively, and I(Ca,L) in mouse ventricular myocytes, using whole-cell patch-clamp. Atorvastatin and SVA produced a concentration-dependent block of hKv1.5 channels (IC(50)=4.5+/-1.7 microM and 5.7+/-0.03 microM, respectively) and shifted the midpoint of the activation and inactivation curves to more negative potentials. Importantly, atorvastatin- and SVA-induced block was added to that produced by quinidine, a drug that blocks hKv1.5 channels by binding to their pore cavity. Atorvastatin and SVA blocked Kv4.3 channels in a concentration-dependent manner (IC(50)=13.9+/-3.6 nM and 7.0+/-0.8 microM, respectively). Both drugs accelerated the inactivation kinetics and shifted the inactivation curve to more negative potentials. SVA (10 nM), but not atorvastatin, also blocked I(Ca,L) producing a frequency-dependent block that, at 2 Hz, reached a 50.2+/-1.5%. As a consequence of these effects, at nanomolar concentrations, atorvastatin lengthened, whereas SVA shortened, the duration of mouse atrial action potentials. The results suggest that atorvastatin and SVA alter Kv1.5 and Kv4.3 channel activity following a complex mechanism that does not imply the binding of the drug to the channel pore.

Oxidized low density lipoproteins induce apoptosis in human lymphocytes: involvement of mitogen-activated protein kinases

Oxidized low density lipoproteins (oxLDL), macrophages and T-lymphocytes are present in atherosclerotic lesions. We and others have shown that oxLDL is cytotoxic for macrophages, endothelial, smooth muscle and activated T-lymphocytes and induce apoptosis. Here we demonstrate that (i) oxidized LDL (oxLDL), oxidized VLDL (oxVLDL) and hydrogen peroxide (H2O2) induce apoptosis in human T-lymphocytes and (ii) mitogen-activated protein kinases are involved in this process. Apoptosis was monitored by immunofluorescence microscopy and flow cytometry for annexin V binding, Apo 2.7 expression, the TUNEL reaction and caspase 3 activity. In the presence of oxLDL (100 microg/ml), oxVLDL (50 microg/ml) and H2O2 (5 mM), the fraction of apoptotic cells increased within 6 hours to more than 70%. Preincubation of lymphocytes with the MAPKK inhibitor PD-98059 and the p38MAPK inhibitor SB-203580 almost completely abolished these effects. Furthermore, oxLDL and H2O2 but not native LDL strongly enhanced phosphorylation of JNK, p38MAPK and p42/44MAPK. The results suggest that in the resting lymphocyte apoptosis triggered by oxidized lipoproteins and oxidative stress depends on the activation of p44/42MAPK and p38MAPK cascades.

Comparison between experimental and calculated vehicle idle emission factors for Madrid fleet

Experimental vehicle idle emission factors have been compared with calculated factors for 100 vehicles in Madrid. The vehicles were selected according to the distribution (by age and fuel type) of the official, national car fleet (up to 31 December 1997). They were then clustered following the criteria of the Computer Programme to Calculate Emissions from Road Transport (COPERT III) category classification. NO(x) and CO idle emission factors show a wide range of values in each category and an important deviation between the experimental values and the corresponding parameterised ones. Fifteen percent of tested vehicles in this study have been identified as gross emitters generating approximately 50% of the total CO emission volume.

Ionization chamber dosimetry of small photon fields: a Monte Carlo study on stopping-power ratios for radiosurgery and IMRT beams

Absolute dosimetry with ionization chambers of the narrow photon fields used in stereotactic techniques and IMRT beamlets is constrained by lack of electron equilibrium in the radiation field. It is questionable that stopping-power ratio in dosimetry protocols, obtained for broad photon beams and quasi-electron equilibrium conditions, can be used in the dosimetry of narrow fields while keeping the uncertainty at the same level as for the broad beams used in accelerator calibrations. Monte Carlo simulations have been performed for two 6 MV clinical accelerators (Elekta SL-18 and Siemens Mevatron Primus), equipped with radiosurgery applicators and MLC. Narrow circular and Z-shaped on-axis and off-axis fields, as well as broad IMRT configured beams, have been simulated together with reference 10 x 10 cm2 beams. Phase-space data have been used to generate 3D dose distributions which have been compared satisfactorily with experimental profiles (ion chamber, diodes and film). Photon and electron spectra at various depths in water have been calculated, followed by Spencer-Attix (delta = 10 keV) stopping-power ratio calculations which have been compared to those used in the IAEA TRS-398 code of practice. For water/air and PMMA/air stopping-power ratios, agreements within 0.1% have been obtained for the 10 x 10 cm2 fields. For radiosurgery applicators and narrow MLC beams, the calculated s(w,air) values agree with the reference within +/-0.3%, well within the estimated standard uncertainty of the reference stopping-power ratios (0.5%). Ionization chamber dosimetry of narrow beams at the photon qualities used in this work (6 MV) can therefore be based on stopping-power ratios data in dosimetry protocols. For a modulated 6 MV broad beam used in clinical IMRT, s(w,air) agrees within 0.1% with the value for 10 x 10 cm2, confirming that at low energies IMRT absolute dosimetry can also be based on data for open reference fields. At higher energies (24 MV) the difference in s(w,air) was up to 1.1%, indicating that the use of protocol data for narrow beams in such cases is less accurate than at low energies, and detailed calculations of the dosimetry parameters involved should be performed if similar accuracy to that of 6 MV is sought.

Retinopatía de Purtscher: complicación infrecuente de la pancreatitis aguda no alcohólica

Purtscher's retinopathy is a rare complication of acute alcoholic pancreatitis that is characterized by the development of cotton-wool exudates and retinal hemorrhages located around the optic disk. Its development is due to ischemic phenomena in the posterior pole of the retina due to microemboli in the retinal arterioles and capillaries. This complication is not related to a poorer prognosis of acute pancreatitis and the retinopathy usually has a favorable outcome with disappearance of the ophthalmic lesions and restoration of visual acuity after 4-6 weeks in most cases. However, some patients may show residual lesions, especially if optical atrophy occurs. We present a 40-year-old woman with loss of visual acuity due to Purtscher's retinopathy during the course of mild acute idiopathic pancreatitis.

Mitochondrial [Ca(2+)] oscillations driven by local high [Ca(2+)] domains generated by spontaneous electric activity

Mitochondria take up calcium during cell activation thus shaping Ca(2+) signaling and exocytosis. In turn, Ca(2+) uptake by mitochondria increases respiration and ATP synthesis. Targeted aequorins are excellent Ca(2+) probes for subcellular analysis, but single-cell imaging has proven difficult. Here we combine virus-based expression of targeted aequorins with photon-counting imaging to resolve dynamics of the cytosolic, mitochondrial, and nuclear Ca(2+) signals at the single-cell level in anterior pituitary cells. These cells exhibit spontaneous electric activity and cytosolic Ca(2+) oscillations that are responsible for basal secretion of pituitary hormones and are modulated by hypophysiotrophic factors. Aequorin reported spontaneous [Ca(2+)] oscillations in all the three compartments, bulk cytosol, nucleus, and mitochondria. Interestingly, a fraction of mitochondria underwent much larger [Ca(2+)] oscillations, which were driven by local high [Ca(2+)] domains generated by the spontaneous electric activity. These oscillations were large enough to stimulate respiration, providing the basis for local tune-up of mitochondrial function by the Ca(2+) signal.

Direct actions of adrenergic agents on rat anterior pituitary cells

We studied the effects of adrenergic agents on the five main cell types of the rat anterior pituitary by monitoring the changes of the cytosolic free [Ca2+] ([Ca2+]i) in single cells that were identified by multiple sequential primary immunocytochemistry at the end of the Ca2+ measurements. Adrenaline (100 nM) increased [Ca2+]i in 30% of the cells. Responses were most prominent in somatotrophs and corticotrophs (40-65% of the cells responded) whereas the other three cell types, lactotrophs, thyrotrophs and gonadotrophs, gave poorer responses. Selective agonists and antagonists revealed the presence of both alpha1- and beta-adrenergic receptors. Alpha1-receptors dominated in corticotrophs, beta-receptors in somatotrophs. The alpha1-adrenergic responses increased with culture of the cells. The beta-adrenergic responses were mediated by cAMP and consisted of stimulation of Ca2+ entry through L-type voltage-gated channels. Stimulation of alpha1-receptors released Ca2+ from intracellular stores in corticotrophs and induced cAMP-independent Ca2+ entry in somatotrophs. The effects of alpha1-agonists were additive with those of the releasing factors growth hormone-releasing hormone (GHRH) and corticotropin releasing factor (CRF) whereas those of the beta-agonists were not. Our results suggest that direct effects of plasma catecholamines on AP cells may contribute to the hormonal response to stress.

[Clinical characterization of 450 patients with cerebrovascular disease admitted to a public hospital during 1997]

BACKGROUND

In Chile, cerebrovascular diseases are the fifth cause of death among men and the third cause among women.

AIM

To assess the clinical features and management of patients with cerebrovascular disease admitted to a public hospital during 1997.

PATIENTS AND METHODS

A retrospective analysis of clinical records of patients discharged with a diagnosis of cerebrovascular disease. Those records in which there was discordance between the discharge diagnosis and the clinical picture were not considered in the analysis.

RESULTS

Of the 563 discharges from the hospital with the diagnosis of cerebrovascular disease, 487 records were located and 450 were considered in the analysis. Fifty four percent of patients were male and ages ranged from 17 to 96 years old. Fifty-one percent of patients had an ischemic stroke, 34% a cerebral hemorrhage, 12% a subarachnoidal hemorrhage and 3% a transient ischemic attack. There was a history of hypertension in 64% patients and 20% had an adequate treatment. Eighteen percent were diabetics, 34% had a heart disease and 20% had a previous episode of stroke. Mean hospital stay was 6.3 days in the emergency room and 11 days in the neurology ward. Hospital infections appeared in 21% of patients (respiratory in 68% and urinary in 22%), lethality was 30.5% and a CAT scan was done in 94%. At the moment of admission, 10% of patients had an evolution of less than 2 hours, 27% had an evolution between 2 and 6 hours and nine cases were potential eligible for thrombolysis.

CONCLUSION

This is a picture of the local features of patients with cerebrovascular diseases that can be used as a reference for future studies.

The relationship between pulsatile secretion and calcium dynamics in single, living gonadotropin-releasing hormone neurons

It is well established that pulsatile release of GnRH regulates the reproductive axis, but little is known about the mechanisms underlying this pulsatility. Recent findings that GT1 cells, a line derived from the mouse embryonic hypothalamus, release GnRH in a pulsatile manner indicates that this rhythmic activity is an intrinsic property of GnRH neurons. In several attempts to uncover the intracellular basis for this pulsatile phenomenon, it was revealed that intracellular calcium concentrations change in a rhythmic fashion in GnRH neurons and that cellular depolarization, which triggers a secretory event, is associated with profound calcium changes in the cells. These findings raised the intriguing possibility that periodic alterations in intracellular calcium concentrations may underlie the phenomenon of pulsatile secretion in GnRH neurons. To address this, we first adapted the use of FM1-43 fluorescence to monitor changes of secretion in individual GT1-7 cells and then combined this approach with simultaneous measurement ofintracellular free calcium ([Ca2+]i, fura 2 method). In initial validation experiments, we found that stimulation of exocytosis with K+ (75 mM) or N-methyl-D-aspartate (NMDA, 100 microM) predictably evoked dynamic increases of both FM1-43 and fura 2 fluorescence. Later measurement of calcium dynamics and exocytotic activity in unstimulated cells revealed that [Ca2+]i underwent transitions from quiescence to high oscillatory behavior, and that these shifts were frequently associated with exocytotic events. Moreover, these calcium oscillatory transitions and associated changes in secretory activity occurred synchronously among most adjacent cells and at a frequency similar to that reported for pulsatile release of GnRH by entire cultures of GnRH neurons. Taken together, these results indicate that the intrinsic secretory pulsatility of GnRH neurons appears to be a consequence of coordinated, periodic changes in the pattern of calcium oscillations within individual cells.

Genetic susceptibility associated with rare HRAS1 variable number of tandem repeats alleles in Spanish non-small cell lung cancer patients

The highly polymorphic HRAS1 variable number of tandem repeats (VNTR), which maps 1 kb downstream from the human H-ras1 gene, has been described as an inherited predisposing factor in many human cancers. Here, we investigated the association between the presence of rare HRAS1 minisatellite alleles and lung cancer in the population studied. Four hundred sixty-six HRAS1 VNTR alleles from 233 lung cancer patients and 892 alleles from 446 unaffected controls were typed using PCR-long agarose gel electrophoresis assay of peripheral blood lymphocyte DNA. Rare alleles were differentiated from common alleles (a1, a2, a3, and a4) by shifts in electrophoretic mobility. Odds ratio was calculated to evaluate increased risk of lung cancer associated to the presence of rare HRAS1 alleles. A higher percentage of rare HRAS1 VNTR alleles in lung cancer patients than in unaffected controls (32.7 versus 21.9%) was confirmed. The presence of rare alleles was associated with an increased risk of lung cancer (odds ratio = 1.68; P < or = 0.0001), indicating a genetic predisposition to lung cancer. No differences based on other clinicopathological variables were observed. Furthermore, a meta-analysis showed a higher distribution of rare alleles in our study of Caucasian Spaniards than was found in other studies of American and Northern European Caucasian populations. We conclude that the presence of rare HRAS1 VNTR alleles may be an inherited predisposing factor in lung cancer. This presence can be easily determined from peripheral blood samples by PCR-based methods. Furthermore, interracial variations in allele frequencies and variations between Caucasian subpopulations suggest that genetic variations may be involved in susceptibility to lung oncogenesis, especially in certain ethnic populations.

Paclitaxel resistance in non-small-cell lung cancer associated with beta-tubulin gene mutations

PURPOSE

The mechanisms that cause chemoresistance in non-small-cell lung cancer (NSCLC) patients have yet to be clearly elucidated. Paclitaxel is a tubulin-disrupting agent that binds preferentially to beta-tubulin. Tubulins are guanosine triphosphate (GTP)-binding proteins. Beta-tubulin is a GTPase, whereas alpha-tubulin has no enzyme activity. We reasoned that polymerase chain reaction (PCR) and DNA sequencing of the beta-tubulin gene could reveal more information regarding the connection between beta-tubulin mutations and primary paclitaxel resistance.

PATIENTS AND METHODS

Constitutional genomic DNA and paired tumor DNA were isolated from 49 biopsies from 43 Spanish and six American stage IIIB and IV NSCLC patients who had been treated with a 3-hour, 210 mg/m(2) paclitaxel infusion and a 24-hour, 200 mg/m(2) infusion, respectively. Oligonucleotides specific to beta-tubulin were designed for PCR amplification and sequencing of GTP- and paclitaxel-binding beta-tubulin domains.

RESULTS

Of 49 patients with NSCLC, 16 (33%; 95% confidence interval [CI], 20.7% to 45.3%) had beta-tubulin mutations in exons 1 (one patient) or 4 (15 patients). None of the patients with beta-tubulin mutations had an objective response, whereas 13 of 33 (39.4%; 95% CI, 22.8% to 56%; P = 0.01) patients without beta-tubulin mutations had complete or partial responses. Median survival was 3 months for the 16 patients with beta-tubulin mutations and 10 months for the 33 patients without beta-tubulin mutations (P =.0001).

CONCLUSION

We have identified beta-tubulin gene mutations as a strong predictor of response to the antitubulin drug paclitaxel; these mutations may represent a novel mechanism of resistance and should be examined prospectively in future trials of taxane-based therapy in NSCLC.

Cholesterol saturation, not proteins or cholecystitis, is critical for crystal formation in human gallbladder bile

BACKGROUND & AIMS

Biliary proteins are promoters of cholesterol crystallization in artificial model bile. However, their pathogenic importance for cholesterol precipitation in native gallbladder bile (GB) is uncertain. The aim of this study was to evaluate the significance of biliary lipids and proteins on cholesterol crystal detection time (ChCDT) of GB in patients with gallstones.

METHODS

ChCDT and concentrations of lipids, albumin, mucins, aminopeptidase N, alpha1-acid glycoprotein, haptoglobin, and immunoglobulins (Igs) were measured in GB of 92 patients, 52 of whom had cholesterol gallstones.

RESULTS

ChCDT was markedly reduced in gallstone patients. Compared with patients without gallstones, they had a significant increase in cholesterol saturation and total protein, albumin, mucin, and IgG biliary concentrations. In univariate analysis, ChCDT of GB was significantly correlated with cholesterol saturation and total lipid, protein, Ig, aminopeptidase N, and alpha1-acid glycoprotein concentrations. However, stepwise logistic regression analysis showed that only cholesterol saturation independently correlated to ChCDT. Gallbladder inflammation correlated with the concentration of Igs, but subtraction of IgG from GB did not modify the ChCDT.

CONCLUSIONS

Biliary cholesterol transport and saturation, but not proteins, appear critical for the cholesterol crystallization abnormality observed in native bile from patients with gallstones.

Multi-responsiveness of single anterior pituitary cells to hypothalamic-releasing hormones: a cellular basis for paradoxical secretion

The classic view for hypothalamic regulation of anterior pituitary (AP) hormone secretion holds that release of each AP hormone is controlled specifically by a corresponding hypothalamic-releasing hormone (HRH). In this scenario, binding of a given HRH (thyrotropin-, growth hormone-, corticotropin-, and luteinizing hormone-releasing hormones) to specific receptors in its target cell increases the concentration of cytosolic Ca2+ ([Ca2+]i), thereby selectively stimulating the release of the appropriate hormone. However, "paradoxical" responses of AP cells to the four well-established HRHs have been observed repeatedly with both in vivo and in vitro systems, raising the possibility of functional overlap between the different AP cell types. To explore this possibility, we evaluated the effects of HRHs on [Ca2+]i in single AP cells identified immunocytochemically by the hormone they stored. We found that each of the five major AP cell types contained discrete subpopulations that were able to respond to several HRHs. The relative abundance of these multi-responsive cells was 59% for lactotropes, 33% for thyrotropes, and in the range of 47-55% for gonadotropes, corticotropes, and somatotropes. Analysis of prolactin release from single living cells revealed that each of the four HRHs tested were able to induce hormone release from a discrete lactotrope subpopulation, the size of which corresponded closely to that in which [Ca2+]i changes were induced by the same secretagogues. When viewed as a whole, our diverse functional measurements of multi-responsiveness suggest that hypothalamic control of pituitary function is more complicated than previously envisioned. Moreover, they provide a cellular basis for the so-called "paradoxical" behavior of pituitary cells to hypothalamic hypophysiotropic agents.

Functional ATP receptors in rat anterior pituitary cells

The effects of ATP and other nucleotides on the cytosolic Ca2+ concentration ([Ca2+]i) of single immunocytochemically typed anterior pituitary (AP) cells have been studied. ATP increased [Ca2+]i in a large percentage (60-88%) of all five AP cell types: lactotropes, somatotropes, corticotropes, gonadotropes, and thyrotropes. Additivity experiments suggest the presence of at least two different receptors, one accepting both ATP and UTP (U receptor), producing Ca2+ release from the intracellular stores, and the other preferring ATP (A receptor), producing Ca2+ (and Mn2+) entry. The characteristics of the U and A receptors were consistent with those of P2Y2 and P2X2, respectively, and their distribution in the different AP cell types was not homogeneous. The presence of other ATP receptors such P2Y1 or P2X2/P2X3 heteropolymers in a small fraction of the cells cannot be excluded. Thus functional ionophoric P2X receptors, which are typical of neural tissue, are also present in the pituitary gland and could contribute to regulation of the gland's function.

Mechanisms for stimulation of rat anterior pituitary cells by arginine and other amino acids

1. Arginine and other amino acids are secretagogues for growth hormone and prolactin in the intact animal, but the mechanism of action is unclear. We have studied the effects of amino acids on cytosolic free calcium concentration ([Ca2+]i) in single rat anterior pituitary (AP) cells. Arginine elicited a large increase of [Ca2+]i) in about 40% of all the AP cells, suggesting that amino acids may modulate hormone secretion by acting directly on the pituitary. 2. Cell typing by immunofluorescence of the hormone the cells store showed that the arginine-sensitive cells are distributed uniformly within all the five AP cell types. The arginine-sensitive cells overlapped closely with the subpopulation of cells sensitive to thyrotrophin-releasing hormone. 3. Other cationic as well as several neutral (dipolar) amino acids had the same effect as arginine. The increase of [Ca2+]i was dependent on extracellular Ca2+ and blocked by dihydropyridine, suggesting that it is due to Ca2+ influx through L-type voltage-gated Ca2+ channels. The [Ca2+]i increase was also blocked by removal of extracellular Na+ but not by tetrodotoxin. The substrate specificity for stimulation of AP cells resembled closely that of the amino acid transport system B0+. We propose that electrogenic amino acid influx through this pathway depolarizes the plasma membrane with the subsequent activation of voltage-gated Ca2+ channels and Ca2+ entry. 4. Amino acids also stimulated prolactin secretion in vitro with a similar substrate specificity to that found for the [Ca2+]i increase. Existing data on the stimulation of secretion of other hormones by amino acids suggest that a similar mechanism could apply to other endocrine glands.

Different contributions of L- and Q-type Ca2+ channels to Ca2+ signals and secretion in chromaffin cell subtypes

In this study, we investigated the contribution of different subtypes of voltage-dependent Ca2+ channels to changes in cytosolic free Ca2+ ([Ca2+]i) and secretion in noradrenergic and adrenergic bovine chromaffin cells. In single immunocytochemically identified chromaffin cells, [Ca2+]i increased transiently during high K+ depolarization. Furnidipine and BAY K 8644, L-type Ca2+ channel blocker and activator, respectively, affected the [Ca2+]i rise more in noradrenergic than in adrenergic cells. In contrast, the Q-type Ca2+ channel blocker omega-conotoxin MVIIC inhibited the [Ca2+]i rise more in adrenergic cells. omega-Agatoxin IVA (30 nM), which blocks P-type Ca2+ channels, had little effect on the [Ca2+]i signal. The N-type Ca2+ channel blocker omega-conotoxin GVIA similarly inhibited the [Ca2+]i rise in both cell types. The effects of furnidipine, BAY K 8644, and omega-conotoxin MVIIC on K+-evoked norepinephrine and epinephrine release paralleled those effects on [Ca2+]i signals. However, omega-conotoxin GVIA and 30 nM omega-agatoxin IVA did not affect the secretion of either amine. The data suggest that, in the bovine adrenal medulla, the release of epinephrine and norepinephrine are preferentially controlled by Q- and L-type Ca2+ channels, respectively. P- and N-type Ca2+ channels do not seem to control the secretion of either catecholamine.

Functional glutamate receptors in a subpopulation of anterior pituitary cells

We have studied the effects of glutamate receptor agonists on the cytosolic Ca2+ concentration ([Ca/+]i) of single rat anterior pituitary (AP) cells. Ionotropic (NMDA and kainate/AMPA) and, to a smaller extent, metabotropic glutamate receptors were both present in all the five AP cell types, defined by the hormone they store. Cells within all the types responded also to thyrotropin-releasing hormone (TRH). Alternative typing by the response to four well-established hypothalamic releasing hormones (HRHs), GHRH, GnRH, CRH, and TRH, was performed. One-third of the cells were not sensitive to any HRH, another third were sensitive to only one HRH, and the last third were sensitive to more than one HRH, frequently to all four. Only the cells responding to TRH showed functional glutamate receptors. Superimposed to the above association, the strongest responses to glutamate were found in the cells responsive to multiple HRHs. These results suggest that glutamate may act, by a nonsynaptic mechanism, as a new releasing factor for one or, like TRH, several AP hormones. Coexpression of glutamate and TRH receptors in the subpopulation of cells responsive to multiple HRHs might have a functional meaning, perhaps related to phenotypic plasticity and long-term regulation of hormone secretion by the anterior pituitary.

Biliary aminopeptidase-N and the cholesterol crystallisation defect in cholelithiasis

Several biliary proteins have cholesterol crystallisation promoting activity. One of these glycoproteins is aminopeptidase-N, a canalicular ectoenzyme. This study attempted to localise aminopeptidase-N along the biliary tree, to assess its concentration in a series of 98 patients subjected to abdominal surgery, 40 of them without gall stones, and to correlate its concentration with cholesterol crystal formation time of gall bladder bile. Aminopeptidase-N was isolated from purified native biliary vesicles. A specific polyclonal rabbit anti-aminopeptidase-N antibody was prepared for quantitative immunoblotting and for immunolocalisation. Tissue was obtained from liver biopsy specimens and from gall bladders removed at surgery because of gall stone disease. Aminopeptidase-N was immunolocalised to the apical membranes of hepatocytes and to the apical pole of ductular and gall bladder mucosal cells. The nucleation time of gall bladder bile was mean (SD) 4 (3) days in the gall stone group, compared with 21 (18) days in the control group (p < 0.001). Total absolute biliary protein and aminopeptidase-N concentrations were similar in both the control and gall stone patients. There was a reciprocal significant correlation, however, between the nucleation time and the relative aminopeptidase-N concentration (r = -0.35, p < 0.01) only in the gall stone group of patients. This study shows that this apical transmembrane ectoenzyme with cholesterol crystallisation promoting activity is present along the biliary tree and the hepatocyte. These findings support the concept that high concentrations or qualitative changes of biliary aminopeptidase-N contribute to cholesterol gall stone formation.

Nitric oxide synthesis in rat peritoneal macrophages is induced by IgE/DNP complexes and cyclic AMP analogues. Evidence in favor of a common signaling mechanism

The production of nitric oxide was studied in rat adherent peritoneal cells stimulated with preformed IgE/DNP-BSA complexes made of IgE obtained from a secreting hybridoma. Stimulation with complexes at equivalence induced both the production of NO and an increased expression of the mRNA of the inducible isoform of NO synthase (iNOS). Production of NO was also elicited by a rabbit polyclonal F(ab')2 anti-CD23 cross-reacting with rat CD23. Because IgE/DNP-BSA complexes did not elicit Ca2+ mobilization and genistein did not influence the production of NO, cyclic AMP was considered as an alternative signaling molecule. Combination of a suboptimal concentration of dibutyryl cyclic AMP and IgE/DNP-BSA complexes showed an additive effect on NO production, whereas this was not observed when the agonists were used at supraoptimal doses. The inhibitor of cyclic AMP-specific phosphodiesterase IV, rolipram, which acts on the enzyme isoform predominantly expressed in inflammatory cells, also induced the production of NO. Furthermore, IgE/DNP-BSA complexes increased intracellular levels of cyclic AMP. Taken together, these data indicate that stimulation of mononuclear phagocytes via the low-affinity receptor Fc epsilon RII or rising intracellular concentrations of cyclic AMP leads to an enhanced expression of iNOS. Evidence in favor of the involvement of cyclic AMP in the signaling pathway linked to Fc epsilon RII is provided by the effect of IgE/DNP-BSA complexes on intracellular cyclic AMP levels and by the additive effect produced by dibutyryl cyclic AMP on NO production elicited by IgE/DNP-BSA complexes.

Nitric oxide synthesis in rat peritoneal macrophages is induced by IgE/DNP complexes and cyclic AMP analogues. Evidence in favor of a common signaling mechanism

The production of nitric oxide was studied in rat adherent peritoneal cells stimulated with preformed IgE/DNP-BSA complexes made of IgE obtained from a secreting hybridoma. Stimulation with complexes at equivalence induced both the production of NO and an increased expression of the mRNA of the inducible isoform of NO synthase (iNOS). Production of NO was also elicited by a rabbit polyclonal F(ab')2 anti-CD23 cross-reacting with rat CD23. Because IgE/DNP-BSA complexes did not elicit Ca2+ mobilization and genistein did not influence the production of NO, cyclic AMP was considered as an alternative signaling molecule. Combination of a suboptimal concentration of dibutyryl cyclic AMP and IgE/DNP-BSA complexes showed an additive effect on NO production, whereas this was not observed when the agonists were used at supraoptimal doses. The inhibitor of cyclic AMP-specific phosphodiesterase IV, rolipram, which acts on the enzyme isoform predominantly expressed in inflammatory cells, also induced the production of NO. Furthermore, IgE/DNP-BSA complexes increased intracellular levels of cyclic AMP. Taken together, these data indicate that stimulation of mononuclear phagocytes via the low-affinity receptor Fc epsilon RII or rising intracellular concentrations of cyclic AMP leads to an enhanced expression of iNOS. Evidence in favor of the involvement of cyclic AMP in the signaling pathway linked to Fc epsilon RII is provided by the effect of IgE/DNP-BSA complexes on intracellular cyclic AMP levels and by the additive effect produced by dibutyryl cyclic AMP on NO production elicited by IgE/DNP-BSA complexes.

Verification of an on line in vivo semiconductor dosimetry system for TBI with two TLD procedures

This work presents the verification of an on line in vivo dosimetry system based on semiconductors. Software and hardware has been designed to convert the diode signal into absorbed dose. Final verification was made in the form of an intercomparison with two independent thermoluminiscent (TLD) dosimetry systems, under TBI conditions.

Protective role of biliary cholesterol and phospholipid lamellae against bile acid-induced cell damage

BACKGROUND/AIMS

Bile salts (BS) are cytotoxic agents, but cell damage is not observed in the hepatobiliary system. We hypothesized that biliary lipid vesicles (unilamellae and multilamellae) could have a protective role against BS-induced cytotoxicity.

METHODS

Biliary lipid lamellar secretion was induced by feeding rats with 0.5% diosgenin. Cytoprotection was assessed in bile duct-obstructed rats and by incubating human erythrocytes with sodium taurocholate.

RESULTS

Biliary cholesterol concentration increased > 300% in diosgenin-fed rats; electron microscopic examination showed a great abundance of lipid lamellar vesicles in bile and within the canaliculi. After bile duct obstruction, serum hepatic enzyme activities were significantly lower in diosgenin-fed rats. Histologically severe and confluent hepatocellular necrosis was only observed in control rats. Biliary lamellar lipid material significantly reduced the BS-induced hemolytic effect in vitro in a concentration-dependent manner. This protective effect correlated to a progressive decrease in the intermicellar BS concentration. Phosphatidylcholine or cholesterol, alone or as lamellar structures, also showed cytoprotective effect in vitro but always less than native biliary lamellae.

CONCLUSIONS

These results support the concept that native biliary cholesterol phospholipid lamellae represent an important cytoprotective factor for hepatocytes and biliary epithelial cells against BS-induced damage.