Política cambiaria y la fijación de metas inflacionarias en Colombia

(Disponible en idioma inglés únicamente) En este trabajo se analiza la experiencia de Colombia con una política monetaria con metas inflacionarias tras el abandono del mecanismo de bandas cambiarias en 1999, así como durante dos episodios, en 2003 y 2004, que se desviaron de este comportamiento general. En esos episodios, el Banco Central intervino en el mercado cambiario de una manera relativamente considerable, para influir en la tendencia del tipo de cambio (flotación controlada). Esos episodios se analizan para extraer enseñanzas y resaltar los principales desafíos que encaran las políticas monetaria y cambiaria. A continuación se analiza la justificación de la intervención del Banco Central en el mercado cambiario colombiano. Por último, el trabajo presenta varias cuestiones que aparecen en el debate sobre la política monetaria y cambiaria de Colombia y se propone una idea del contexto político en el que se toman las decisiones de la política monetaria.

¿A que Juegan el Gobierno y un Banco Central Independiente?

Una consecuencia de la independencia del banco central (BC) es la posibilidad de que se presenten diferencias entre los objetivos del gobierno (G) y el banco. Estas notas pretenden ilustrar algunas de las interacciones estratégicas entre el gobierno y un banco central independiente con objetivos divergentes, bajo supuestos alternativos sobre la información que poseen el BC; el G y el sector privado. Cukieman (1992) señala dos tipos de diferencias entre los objetivos del G y el BC: aquellas referentes a las tasas intertemporales de descuento (el Banco suele tener una visión de más largo plazo), y las relativas a los pesos o valoraciones que los agentes asignan a diferentes objetivos. Este trabajo se concentra en las diferencias del segundo tipo, y presenta algunos ejemplos derivados a partir de un modelo estático (de un solo período) de oferta y demanda agregadas en una economía abierta, con expectativas racionales. Los resultados de estas simulaciones resaltan el hecho de que los supuestos sobre la distribución de la información entre el G, el BC y el sector privado son cruciales en la determinación de la inflación y la tasa de cambio real de equilibrio. Al mismo tiempo, se presentan algunos indicios sobre las condiciones bajo las cuales el G y el BC encuentran mutuamente provechoso coordinar sus políticas. Finalmente, los ejemplos muestran que para reducir la inflación, la estabilidad de precios debe ser el primordial (o único) objetivo del BC, y que si el BC ha de reducir la inflación y alcanzar una meta de tasa de cambio real al mismo tiempo, es necesario que el G no se encuentre en una posición inicial ventajosa. (i.e. se necesita un BC altamente independiente).

Síndrome neuroléptico maligno inducido por risperidona y facilitado por sepsis de origen urinario: clínica y fisiopatología.

Risperidone is a selective monoaminergic antagonist with a high affinity for dopamine receptors that can cause neuroleptic malignant syndrome (NMS), considered a life-threatening medical emergency. It has an incidence of up to 3% and its mortality is between 10 and 20%. The case of a 56-year-old female who met the clinical criteria of NMS, induced by the use of risperidone and facilitated by a sepsis of urinary origin, is reported. It was managed with a dopamine agonist and the change of antipsychotic, which resulted in a favorable clinical course. The NMS is a low-prevalence entity whose diagnosis has specificity and sensitivity greater than 90%, reason for which must be clearly differentiated from other pathologies. The mechanism by which urinary infection could facilitate the occurrence of this disease is discussed. Early diagnosis improves the response to an adequate management to be established in each case.La risperidona es un antagonista selectivo monoaminérgico, con una elevada afinidad por receptores dopaminérgicos, que puede producir síndrome neuroléptico maligno (SNM), considerado una emergencia médica con alto riesgo de muerte. Tiene una incidencia de hasta el 3% y su mortalidad está entre el 10 y 20%. Se reporta el caso de una paciente de 56 años, que reunía los criterios clínicos del SNM, inducido por el uso de risperidona y facilitado por una sepsis de origen urinario. El tratamiento se condujo con un agente agonista dopaminérgico y cambio del antipsicótico, procedimientos que resultaron en una adecuada evolución clínica. El SNM es una entidad de baja prevalencia, para la cual existen criterios diagnósticos con especificidad y sensibilidad mayor del 90%, por lo que debe diferenciarse claramente de otras patologías. Se discute el mecanismo mediante el cual la infección urinaria facilitaría la ocurrencia de esta enfermedad. El diagnóstico precoz mejora la respuesta al manejo adecuado que se establezca en cada caso

Plasma BDNF Levels Vary in Relation to Body Weight in Females

Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of depression as well as neuropsychiatric and neurodegenerative disorders. Recent studies show a role of BDNF in energy metabolism and body weight regulation. We examined BDNF levels in plasma and cerebrospinal fluid (CSF) samples from age matched elderly depressed and control subjects. Also, the association of BDNF levels with age, gender, body weight, body mass index (BMI), and cognitive performance was evaluated. We did not find any significant differences in plasma and CSF BDNF levels between depressed and control subjects. Plasma BDNF levels were negatively correlated with age (but not with BMI and body weight), when analyses were performed including both depressed and control subjects. A significant reduction in plasma BDNF levels was observed in females as compared to male subjects, and the change in BDNF levels were significantly and positively related to body weight in females. Furthermore, significant increases in Total Recall and Delayed Recall values were found in females as compared to males. In conclusion, the lower BDNF levels observed in females suggest that changes in peripheral BDNF levels are likely secondary to an altered energy balance. However, further studies using larger sample size are warranted

Palmitoylation Regulates Epidermal Homeostasis and Hair Follicle Differentiation

Palmitoylation is a key post-translational modification mediated by a family of DHHC-containing palmitoyl acyl-transferases (PATs). Unlike other lipid modifications, palmitoylation is reversible and thus often regulates dynamic protein interactions. We find that the mouse hair loss mutant, depilated, (dep) is due to a single amino acid deletion in the PAT, Zdhhc21, resulting in protein mislocalization and loss of palmitoylation activity. We examined expression of Zdhhc21 protein in skin and find it restricted to specific hair lineages. Loss of Zdhhc21 function results in delayed hair shaft differentiation, at the site of expression of the gene, but also leads to hyperplasia of the interfollicular epidermis (IFE) and sebaceous glands, distant from the expression site. The specific delay in follicle differentiation is associated with attenuated anagen propagation and is reflected by decreased levels of Lef1, nuclear β-catenin, and Foxn1 in hair shaft progenitors. In the thickened basal compartment of mutant IFE, phospho-ERK and cell proliferation are increased, suggesting increased signaling through EGFR or integrin-related receptors, with a parallel reduction in expression of the key differentiation factor Gata3. We show that the Src-family kinase, Fyn, involved in keratinocyte differentiation, is a direct palmitoylation target of Zdhhc21 and is mislocalized in mutant follicles. This study is the first to demonstrate a key role for palmitoylation in regulating developmental signals in mammalian tissue homeostasis

The CARMENES search for exoplanets around M dwarfs High-resolution optical and near-infrared spectroscopy of 324 survey stars

The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520–1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700–900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s−1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3–4 m s−1