Predator arrival elicits differential dispersal, change in age structure and reproductive performance in a prey population.

Predators are an important ecological and evolutionary force shaping prey population dynamics. Ecologists have extensively assessed the lethal effects of invasive predators on prey populations. However, the role of non-lethal effects, such as physiological stress or behavioural responses like dispersal, has been comparatively overlooked and their potential population effects remain obscure. Over the last 23 years, we developed a mark-recapture program for the Audouin's gull and an intensive carnivore monitoring program to assess how the appearance and invasion of the study site by carnivores affects population dynamics. We evaluate changes in turnover of discrete breeding patches within the colony, age structure and breeding performance. Once carnivores entered the colony, the number of occupied patches increased, indicating a higher patch turnover. Breeders responded by moving to areas less accessible to carnivores. More importantly, the presence of carnivores caused differential (and density-independent) breeding dispersal: experienced, better-performing breeders were more likely to leave the colony than younger breeders. This differential dispersal modified the age structure and reduced the reproductive performance of the population. Our results confirm the importance experience in the study of populations. The role of differential dispersal for animal population dynamics might be more important than previously thought, especially under scenarios of global change.

Controversias respecto al uso de estatinas en el síndrome coronario agudo / Controversies regarding the use of statins in the acute coronary syndrome

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[Postorthodontic retention with a rigid resin splint]. / Contention postorthodontique avec attelle rigide en résine.

We have done a clinical review of 30 cases of post-orthodontic retention with resin splint, from canine to canine in both maxillary. We describe the procedure of making the splint, its placement, their incidence or clinical problems (inadequate adhesion, gingivitis...) and the psychologic or subjective patient aspects.

[The prevalence of anti-hepatitis virus C antibodies in chronic hemodialysis patients]. / Prevalencia de anticuerpos anti-hepatitis por virus C en hemodializados crónicos.

Liver involvement with a variety of viral diseases is a frequent finding in chronic renal failure patients on regular hemodialysis treatment. We evaluated the prevalence of IgG anti-hepatitis C virus antibodies (HVC) in our dialysis unit, looking for risk factors associated with seropositivity and we assessed the type and degree of liver involvement by means of a liver biopsy in those patients with biochemical abnormalities of liver function test. We studied 50 patients aged 13 to 77 years, and performed serial determinations of serum ALT (UI/L). IgG anti HVC was determined by a second generation ELISA Kit (Abbot). We retrieved information from chart review and patient interview, regarding: time on hemodialysis, number of blood transfusions and intravenous IV drug use off dialysis. Liver biopsy specimens were stained with H.E. and Masson and findings were classified as chronic persistent, chronic active hepatitis or cirrhosis, according to Schewer. We compared the findings with those of other patients with liver dysfunction and positive IgG anti HVC who did not have renal failure. Anti-HVC prevalence in our hemodialysis patients was 44%. Anti-HVC seropositive hemodialysed (HD) patients were not different from seronegative HD patients, with regard to age, sex, i.v. drugs usage and peak ALT values. Twelve of 22 HVC positive patients had peak ALT values higher than 40 UI/L (Table 2). Time in HD (75.5 +/- 42.8 m) and number of blood transfusions received (35.3 +/- 28) were clearly different in HVC positive patients, compared to HVC negatives. Histologically, 11 seropositive patients showed chronic persistent hepatitis as the most frequent finding.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalencia de anticuerpos anti-hepatitis por virus C en hemodializados crónicos. / [The prevalence of anti-hepatitis virus C antibodies in chronic hemodialysis patients]

Liver involvement with a variety of viral diseases is a frequent finding in chronic renal failure patients on regular hemodialysis treatment. We evaluated the prevalence of IgG anti-hepatitis C virus antibodies (HVC) in our dialysis unit, looking for risk factors associated with seropositivity and we assessed the type and degree of liver involvement by means of a liver biopsy in those patients with biochemical abnormalities of liver function test. We studied 50 patients aged 13 to 77 years, and performed serial determinations of serum ALT (UI/L). IgG anti HVC was determined by a second generation ELISA Kit (Abbot). We retrieved information from chart review and patient interview, regarding: time on hemodialysis, number of blood transfusions and intravenous IV drug use off dialysis. Liver biopsy specimens were stained with H.E. and Masson and findings were classified as chronic persistent, chronic active hepatitis or cirrhosis, according to Schewer. We compared the findings with those of other patients with liver dysfunction and positive IgG anti HVC who did not have renal failure. Anti-HVC prevalence in our hemodialysis patients was 44

. Anti-HVC seropositive hemodialysed (HD) patients were not different from seronegative HD patients, with regard to age, sex, i.v. drugs usage and peak ALT values. Twelve of 22 HVC positive patients had peak ALT values higher than 40 UI/L (Table 2). Time in HD (75.5 +/- 42.8 m) and number of blood transfusions received (35.3 +/- 28) were clearly different in HVC positive patients, compared to HVC negatives. Histologically, 11 seropositive patients showed chronic persistent hepatitis as the most frequent finding.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalencia de anticuerpos anti-hepatitis por virus C en hemodializados crónicos. / [The prevalence of anti-hepatitis virus C antibodies in chronic hemodialysis patients]

Liver involvement with a variety of viral diseases is a frequent finding in chronic renal failure patients on regular hemodialysis treatment. We evaluated the prevalence of IgG anti-hepatitis C virus antibodies (HVC) in our dialysis unit, looking for risk factors associated with seropositivity and we assessed the type and degree of liver involvement by means of a liver biopsy in those patients with biochemical abnormalities of liver function test. We studied 50 patients aged 13 to 77 years, and performed serial determinations of serum ALT (UI/L). IgG anti HVC was determined by a second generation ELISA Kit (Abbot). We retrieved information from chart review and patient interview, regarding: time on hemodialysis, number of blood transfusions and intravenous IV drug use off dialysis. Liver biopsy specimens were stained with H.E. and Masson and findings were classified as chronic persistent, chronic active hepatitis or cirrhosis, according to Schewer. We compared the findings with those of other patients with liver dysfunction and positive IgG anti HVC who did not have renal failure. Anti-HVC prevalence in our hemodialysis patients was 44

. Anti-HVC seropositive hemodialysed (HD) patients were not different from seronegative HD patients, with regard to age, sex, i.v. drugs usage and peak ALT values. Twelve of 22 HVC positive patients had peak ALT values higher than 40 UI/L (Table 2). Time in HD (75.5 +/- 42.8 m) and number of blood transfusions received (35.3 +/- 28) were clearly different in HVC positive patients, compared to HVC negatives. Histologically, 11 seropositive patients showed chronic persistent hepatitis as the most frequent finding.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatotoxicidad por amiodarona en ratas / Hepatotoxicity of amiodarone in rats

El uso prolongado de amiodarona en dosis terapéuticas, ha sido recientemente descripto hepatotóxico en seres humanos. El objetivo de nuestro trabajo fue detectar anormalidades bioquímicas e histopatológicas de lesión hepatocelular, para lo cual se utilizaron ratas albinas tratadas durante 90 días con ClA; A: 0,6mg/100g; B: 1,2mg/100g; C: 1,8mg/100g, y D: grupo control, recibió el vehículo de la droga, obteniéndose muestras de sangre a los 0, 30, 60 y 90 días para dosaje de GOT-GPT. Al finalizar el estudio se sacrificaron 6 animales por grupo y los hígados estudiados mediante MO y ME. Solamente en el grupo C se observó una elevación significativa de los niveles séricos de GOT (p<0,001 y p<0,02) a los 30 y 60 días, respectivamente. El estudio de MO demostró la presencia de necrosis centrolobulillar e infiltrados de mono y polinucleares en áreas de necrosis y periportales en la mayor parte de los animales tratados . El examen de ME reveló la presencia de corpúsculos lamelares concéntricos intralisosomales en todos los grupos tratados con CIA, además intenso desarrollo del REL, predominantemente el grupo A. Los grupos B y C mostraron además la presencia de corpúsculos densos rodeando el canalículo biliar, similares a telolisosomas y metamorfosis grasa en focos. En conclusión, ClA se comportó como un hepatotóxico demostrado histológicamente con poca relevancia en los marcadores serológicos enzimáticos en los intervalos de tiempo usados

Hepatotoxicidad por amiodarona en ratas / Hepatotoxicity of amiodarone in rats

El uso prolongado de amiodarona en dosis terapéuticas, ha sido recientemente descripto hepatotóxico en seres humanos. El objetivo de nuestro trabajo fue detectar anormalidades bioquímicas e histopatológicas de lesión hepatocelular, para lo cual se utilizaron ratas albinas tratadas durante 90 días con ClA; A: 0,6mg/100g; B: 1,2mg/100g; C: 1,8mg/100g, y D: grupo control, recibió el vehículo de la droga, obteniéndose muestras de sangre a los 0, 30, 60 y 90 días para dosaje de GOT-GPT. Al finalizar el estudio se sacrificaron 6 animales por grupo y los hígados estudiados mediante MO y ME. Solamente en el grupo C se observó una elevación significativa de los niveles séricos de GOT (p<0,001 y p<0,02) a los 30 y 60 días, respectivamente. El estudio de MO demostró la presencia de necrosis centrolobulillar e infiltrados de mono y polinucleares en áreas de necrosis y periportales en la mayor parte de los animales tratados . El examen de ME reveló la presencia de corpúsculos lamelares concéntricos intralisosomales en todos los grupos tratados con CIA, además intenso desarrollo del REL, predominantemente el grupo A. Los grupos B y C mostraron además la presencia de corpúsculos densos rodeando el canalículo biliar, similares a telolisosomas y metamorfosis grasa en focos. En conclusión, ClA se comportó como un hepatotóxico demostrado histológicamente con poca relevancia en los marcadores serológicos enzimáticos en los intervalos de tiempo usados (AU)