Tercera sesión del panel de expertos sobre la dinámica de la población de anchoveta peruana, julio de 1972

La tercera sesión del panel de expertos hace un reencuentro de las condiciones oceanográficas entre el año 1971 y 1972 respecto a la pesquería de la anchoveta.

Informe de la Cuarta sesión del panel de expertos de la evaluación del stock de anchoveta peruana

Se presenta una revisión de los sucesos de las pesquerías en el lapso desde la anterior reunión del Panel en Julio, 1972 y de lo que se piensa ha tenido lugar en el recurso y en su medio ambiente; se indican diversas líneas de investigación del stock. Se resume la evidencia colateral acerca de los stocks y de su medio ambiente; ésta se relaciona con el fenómeno de El Niño, con las aves guaneras, el aumento de las capturas de sardinas, el contenido graso de la anchoveta y los estadios de maduración de la misma. Cada una de estas entidades indican que recientemente han prevalecido condiciones especiales en el ambiente de la anchoveta, en la biota asociada y en ciertos aspectos de su fisiología. Se ha hecho una detallada revisión de varios tipos de investigación de las poblaciones de anchoveta y de las evidencias que, acerca del estado del recurso, pueden derivarse de tales investigaciones. Se examinó la evidencia obtenida del uso de equipo acústico en el estudio de la distribución de stocks y en la estimación de su abundancia; el trabajo se realizó mediante exploraciones de varias embarcaciones (exploraciones Eureka) y de exploraciones especiales con el barco de investigación SNP-1; también se hizo uso de equipo eco-integrador. Se discuten las fuentes de errores sistemáticos existentes en ese trabajo. Se llega a la conclusión que lo que ese trabajo indicó fue que en Febrero de 1973 existía alrededor de 4 millones de toneladas de anchoveta.

Segundo panel de expertos:informe sobre los efectos económicos de diferentes medidas regulatorias de la pesquería de la Anchoveta peruana

En el informe de su cuarta reunión el Panel de Expertos en Dinámica revisó los datos proporcionados por el Instituto del Mar del Perú sobre el presente estado del stock de la anchoveta. Estos datos mostraron, evidentemente, que el stock de ancho veta se encontraba en una crítica situación a comienzos de 1973. Los mejores cálculos indicaban que la mayor captura que podría obtenerse en 1973 sería alrededor de a millones de toneladas pero que sería conveniente mantencrla muy por debajo de este nivel, especialmente antes de la mayor temporada de desove en Agosto-Setiembre. En 1974 el reclutamiento podía ser muy bajo especialmente si el stock desovante seguía siendo agotado por la pesca, de modo que las capturas en 1974 podrían ser mucho más bajas del promedio aún en el caso de que no hubiera restricciones para la pesca.

Informe de la primera sesión del panel internacional de expertos para evaluación de la población de la merluza peruana. Marzo 2003

Presentan los resultados del trabajo del panel siguiendo la secuencia establecida en los términos de referencia: estimar el estatus del stock de la merluza peruana, Proveer proyecciones del rendimiento y desarrollo del stock, bajo un escenario pesquero apropiado para el stock de la merluza peruana, comentar sobre medidas administrativas apropiadas de corto y mediano plazo, para la merluza peruana.

Informe de la segunda sesión del panel internacional de expertos para evaluación de la población de la merluza peruana. Marzo 2004

Evalua los resultados del trabajo del Panel de acuerdo con los términos de referencia: actualizar la evaluación y estimar el estatus del stock de la merluza peruana, evaluar el stock desovante y la ojiva de madurez, proponer una cuota para el año 2004, revisar los datos de los cruceros para determinar si existe merluza fuera del área geográfica muestreada, proveer proyecciones del rendimiento y desarrollo del stock bajo esquemas pesqueros apropiados para la merluza peruana.

V panel internacional de expertos en evaluación de la Anchoveta Peruana (Engraulis ringens Jenyns)

Estudia la información sobre los procesos biológicos de la anchoveta y su dinámica poblacional frente a la variabilidad ambiental, en el marco de un enfoque ecosistémico, que permita caracterizar el rol actual de la anchoveta en el Ecosistema de Afloramiento frente al Perú, proporcionando mayores elementos para el desarrollo sustentable de su pesquería.

Convergence in panel data: Evidence from the skipping estimation

This paper demonstrates that, unlike what the conventional wisdom says, measurement error biases in panel data estimation of convergence using OLS with fixed effects are huge, not trivial. It does so by way of the "skipping estimation"': taking data from every m years of the sample (where m is an integer greater than or equal to 2), as opposed to every single year. It is shown that the estimated speed of convergence from the OLS with fixed effects is biased upwards by as much as 7 to 15%.

Marker-free phase nanoscopy

We introduce a microscopic method that determines quantitative optical properties beyond the optical diffraction limit and allows direct imaging of unstained living biological specimens. In established holographic microscopy, complex fields are measured using interferometric detection, allowing diffraction-limited phase measurements. Here, we show that non-invasive optical nanoscopy can achieve a lateral resolution of 90 nm by using a quasi-2 pi-holographic detection scheme and complex deconvolution. We record holograms from different illumination directions on the sample plane and observe subwavelength tomographic variations of the specimen. Nanoscale apertures serve to calibrate the tomographic reconstruction and to characterize the imaging system by means of the coherent transfer function. This gives rise to realistic inverse filtering and guarantees true complex field reconstruction. The observations are shown for nanoscopic porous cell frustule (diatoms), for the direct study of bacteria (Escherichia coil), and for a time-lapse approach to explore the dynamics of living dendritic spines (neurones).

Is carbohydrate-deficient transferrin a specific marker for alcohol abuse? A study in patients with chronic viral hepatitis.

Carbohydrate-deficient transferrin, a transferrin isoform, is hailed as a new marker of chronic alcohol abuse, but its specificity is, however, not unequivocally accepted. The aim of the present study was therefore to determine carbohydrate-deficient transferrin levels in patients with chronic hepatitis B and C with or without documented chronic alcohol intake. Carbohydrate-deficient transferrin was measured using a double-antibody radioimmunoassay (CDTect, Pharmacia) in serum samples from 66 patients (45 males and 21 females; mean age: 39 years) with chronic viral hepatitis B (n = 20) or C (n = 46). Diagnosis of the underlying liver disease was established by liver biopsy. Carbohydrate-deficient transferrin levels were raised in 15 patients [23%; hepatitis B (n = 2) and hepatitis C (n = 13)]. In patients with chronic hepatitis B, the carbohydrate-deficient transferrin level was raised in two abstainers. In the 46 patients with chronic hepatitis C, 10 (22%) patients with an alcohol consumption of < 60 g/day for the men and 30 g/day for the women had raised carbohydrate-deficient transferrin levels. The overall specificity of carbohydrate-deficient transferrin for chronic alcohol abuse was thus 78%, suggesting an association between elevated carbohydrate-deficient transferrin levels and the presence of chronic viral hepatitis. Carbohydrate-deficient transferrin levels were not correlated with the histological grading or staging of chronic hepatitis B and C, or with biological markers of hepatic synthesis and cellular damage. Thus, an increased carbohydrate-deficient transferrin level may occur in patients with chronic viral hepatitis in the absence of chronic alcohol abuse. This fact should be kept in mind by physicians when using this marker to detect alcohol abuse.

Notas sobre el estado actual del stock de anchoveta a base del informe del panel de expertos realizado en julio de 1972 y de los últimos estudios y prospecciones bio-oceanológicas efectuados por el Instituto del Mar

Revisa los acontecimientos recientes de la pesquería de anchoveta a la luz de las investigaciones contínuas realizadas y de las conclusiones del terce informe del Panel de Expertos en dinámica de poblaciones.

Comparison of organ doses and image quality between CT and flat panel XperCT scans in wrist and inner ear examinations.

The aim of this study was to evaluate and compare organ doses delivered to patients in wrist and petrous bone examinations using a multislice spiral computed tomography (CT) and a C-arm cone-beam CT equipped with a flat-panel detector (XperCT). For this purpose, doses to the target organ, i.e. wrist or petrous bone, together with those to the most radiosensitive nearby organs, i.e. thyroid and eye lens, were measured and compared. Furthermore, image quality was compared for both imaging systems and different acquisition modes using a Catphan phantom. Results show that both systems guarantee adequate accuracy for diagnostic purposes for wrist and petrous bone examinations. Compared with the CT scanner, the XperCT system slightly reduces the dose to target organs and shortens the overall duration of the wrist examination. In addition, using the XperCT enables a reduction of the dose to the eye lens during head scans (skull base and ear examinations).

Pyrroloquinoline quinone biosynthesis gene pqqC, a novel molecular marker for studying the phylogeny and diversity of phosphate-solubilizing pseudomonads.

Many root-colonizing pseudomonads are able to promote plant growth by increasing phosphate availability in soil through solubilization of poorly soluble rock phosphates. The major mechanism of phosphate solubilization by pseudomonads is the secretion of gluconic acid, which requires the enzyme glucose dehydrogenase and its cofactor pyrroloquinoline quinone (PQQ). The main aim of this study was to evaluate whether a PQQ biosynthetic gene is suitable to study the phylogeny of phosphate-solubilizing pseudomonads. To this end, two new primers, which specifically amplify the pqqC gene of the Pseudomonas genus, were designed. pqqC fragments were amplified and sequenced from a Pseudomonas strain collection and from a natural wheat rhizosphere population using cultivation-dependent and cultivation-independent approaches. Phylogenetic trees based on pqqC sequences were compared to trees obtained with the two concatenated housekeeping genes rpoD and gyrB. For both pqqC and rpoD-gyrB, similar main phylogenetic clusters were found. However, in the pqqC but not in the rpoD-gyrB tree, the group of fluorescent pseudomonads producing the antifungal compounds 2,4-diacetylphloroglucinol and pyoluteorin was located outside the Pseudomonas fluorescens group. pqqC sequences from isolated pseudomonads were differently distributed among the identified phylogenetic groups than pqqC sequences derived from the cultivation-independent approach. Comparing pqqC phylogeny and phosphate solubilization activity, we identified one phylogenetic group with high solubilization activity. In summary, we demonstrate that the gene pqqC is a novel molecular marker that can be used complementary to housekeeping genes for studying the diversity and evolution of plant-beneficial pseudomonads.

Simple and fast methods based on solid-phase extraction coupled to liquid chromatography with UV detection for the monitoring of caffeine in natural and waste waters as marker of anthropogenic impact

Two concentration methods for fast and routine determination of caffeine (using HPLC-UV detection) in surface, and wastewater are evaluated. Both methods are based on solid-phase extraction (SPE) concentration with octadecyl silica sorbents. A common “offline” SPE procedure shows that quantitative recovery of caffeine is obtained with 2 mL of an elution mixture solvent methanol-water containing at least 60% methanol. The method detection limit is 0.1 μg L−1 when percolating 1 L samples through the cartridge. The development of an “online” SPE method based on a mini-SPE column, containing 100 mg of the same sorbent, directly connected to the HPLC system allows the method detection limit to be decreased to 10 ng L−1 with a sample volume of 100 mL. The “offline” SPE method is applied to the analysis of caffeine in wastewater samples, whereas the “on-line” method is used for analysis in natural waters from streams receiving significant water intakes from local wastewater treatment plants

Sarcomeric M-band alterations as a marker for human dilated cardiomyopathy

Purpose: The M-band is an important cytoskeletal structure in the centre of the sarcomere, believed to cross-link the thick filament lattice. Its main components are three closely related modular proteins from the myomesin gene family: Myomesin, M-protein and myomesin-3. Each muscle is characterized by its unique M-band protein composition, depending on the contractile parameters of a particular fiber. To investigate the role of the M-band in one of the most relevant and clinically increasing cardiac diseases, we analyzed the expression of myomesin proteins in dilated cardiomyopathy (DCM).Methods: In a previous study we analyzed mouse models suffering from DCM, demonstrating that the embryonic heart specific EH-myomesin splicing isoform was up-regulated directly corresponding to the degree of cardiac dysfunction and ventricular dilation. Based on this study, human ventricular and atrial samples (n=32) were obtained during heart surgery after informed consent and approval by an institutional review board. Patients were aged 30-70 years and suffered from dilated cardiomyopathy (DCM;n=13), Hypertrophic Cardiomyopathy (HCM;n=10) or served as controls (n=9). Patients suffering from DCM or HCM were in endstage heart-failure (NYHA III-IV) and either underwent heart transplantation or Left Ventricular Assist Device (LVAD) implantation. Heart samples from patients who underwent valve surgery or congenital heart surgery served as controls. Heart Samples were analyzed using RT-PCR, Western blot, and immunofluorescence.Results: By investigating the expression pattern of myomesins, we found that DCM is accompanied by specific M-band alterations, which were more pronounced in ventricular samples compared to the atrium. Changes in the amounts of different myomesins during DCM occurred in a cell-specific manner, leading to a higher heterogeneity of the cytoskeleton in cardiomyocytes through the myocardial wall with some cells switching completely to an embryonic phenotype.Conclusions: Here we present that the embryonic heart specific EH-myomesin isoform is up-regulated in human DCM. The alterations of the M-band protein composition might be part of a general adaptation of the sarcomeric cytoskeleton to unfavorable working conditions in the failing heart and may modify the mechanical properties of the cardiomyocytes. We suggest that the upregulation of EH-myomesin might play a pivotal role in DCM and might support classical imagingas a novel sarcomeric marker for this disease.