Reproducción de conejos bajo condiciones tropicales, efectos negativos y posibles soluciones / Reproduction of rabbits under tropical conditions, negative effects and possible solutions

RESUMEN La fisiología digestiva y capacidad reproductiva hacen del conejo una especie con potencial para la producción de carne. En clima templado, su adecuado manejo reproductivo permite obtener entre 6 y 10 partos anuales con camadas de 6 y hasta 12 gazapos. En zonas tropicales, el estrés calórico disminuye su capacidad reproductiva. Las hembras presentan un incremento en la secreción de corticosteroides, modificando la secreción de la hormona liberadora de gonadotropina (GnRH), la hormona estimulante del folículo (FSH) y la hormona luteinizante (LH), disminuyendo el crecimiento y desarrollo folicular, calidad de ovocitos y la ovulación, y con ello el número de partos y tamaño de camada. En los machos se afecta la libido y la capacidad de monta. En la calidad seminal, disminuye 7.8 % el volumen, 7.7 % la concentración, 1.7 % la morfología y 5.5 % la motilidad. El objetivo del presente trabajo fue describir las estrategias utilizadas para disminuir el estrés calórico, que incluyó regular la temperatura en las instalaciones, suplementos alimenticios, cruzamiento de razas locales con razas mejoradas, desarrollo de líneas genéticas para climas tropicales, implementación de biotecnologías reproductivas como la inseminación artificial o criopreservación de semen, mejorando el comportamiento reproductivo del conejo bajo condiciones tropicales.

ABSTRACT The digestive physiology and reproductive capacity of the rabbit make it a species with potential for meat production. In a temperate climate, its adequate reproductive management allows to obtain between 6 and 10 annual litters per female with 6 up to 12 kits per litter. In tropical areas, heat stress alters metabolism and hormonal function, decreasing their reproductive capacity. In females, the main changes include an increase in the secretion of corticosteroids, modifying the secretion of gonadotropinreleasing hormone (GnRH), stimulating follicle hormone (FSH) and luteinizing hormone (LH), decreasing the growth and follicular development, oocyte quality and ovulation, and with it the number of births and size of litter. In males, libido and ability to mate are affected. In the seminal quality, a decrease of 7.8 % in volume, 7.7 % in concentration, 1.7 % in morphology and 5.5 % in motility is observed. The objective of the present work was to describe the strategies used to reduce the caloric stress. These included regulating the temperature in the facilities, supplementary food, crossing of local breeds with improved breeds, development of genetic lines for tropical climates, implementation of reproductive biotechnologies such as artificial insemination or cryopreservation of semen, improving the reproductive behavior of the rabbit under tropical conditions.

A streamlined protocol for extracting RNA and genomic DNA from archived human blood and muscle.

We combined the TRIzol method of nucleic acid extraction with QIAamp columns to achieve coextraction of RNA and genomic DNA from peripheral blood mononuclear cells (PBMCs) and biopsied skeletal muscle, both stored at -80 °C for many months. Total RNA was recovered from the upper aqueous phase of TRIzol. The interphase and organic phases were precipitated with ethanol, digested with proteinase K, and filtered through QIAamp MinElute columns to recover DNA. The combined protocol yielded excellent quality and quantity of nucleic acids from archived human PBMCs and muscle and may be easily adapted for other tissues.

Alpha-fetoprotein and tumour size are associated with microvascular invasion in explanted livers of patients undergoing transplantation with hepatocellular carcinoma.

BACKGROUND: To determine factors associated with outcomes and microvascular invasion (MVI) in patients undergoing liver transplantation (LT) for hepatocellular carcinoma (HCC). METHODS: Between July 1996 and August 2008 at the Universities of Kentucky or Tennessee, LT recipients were retrospectively analysed. RESULTS: One hundred and one patients had HCC in the explanted liver; one patient was excluded because of fibrolamellar histology. Seventy-nine (79%) were male and 81 (81%) were older than 50. HCC was incidental in 32 patients (32%). Median follow-up was 31 months. Ten patients (10%) developed recurrence, which was associated with poor survival (P= 0.006). Overall 1-, 3-, and 5-year survival rates were 87%, 69% and 62%, respectively. Excluding patients with lymph node metastasis (LNM) or MVI yielded 91%, 81% and 75% survival at the same time points. MVI was independently associated with recurrence (OR 28.40, 95% CI 1.77-456.48, P= 0.018) and decreased survival (OR 4.70, 95% CI 1.24-17.80, P= 0.023), and LNM with decreased survival (OR 6.05, 95% CI 1.23-29.71, P= 0.027). Tumour size (OR 4.1, 95% CI 1.2-13.5, P= 0.013) and alpha-fetoprotein (AFP) > 100 (OR 5.0, 95% CI 1.4-18.1, P= 0.006) were associated with MVI. CONCLUSIONS: MVI greatly increases the risk of recurrence and death after LT for HCC, and is strongly associated with tumour size and AFP > 100.

Comparison of sirolimus-based calcineurin inhibitor-sparing and calcineurin inhibitor-free regimens in cadaveric renal transplantation.

INTRODUCTION: This study examines the efficacy and toxicity of sirolimus used as primary immunosuppression in combination with reduced dose tacrolimus (calcineurin inhibitor [CI]-sparing regimen) or mycophenolate mofetil (CI-free regimen) in high-risk cadaveric renal transplantation. METHODS: Seventy subjects were treated in a quadruple sequential protocol in which 41 were treated with a CI-sparing regimen and 29 were treated with a CI-free regimen. The efficacy and toxicity profiles of these regimens were prospectively monitored and compared. RESULTS: The study consisted of African Americans (71%), cadaveric donors (100%), donors aged more than 50 years (30%), and patients with delayed graft function (47%). At 1 year, patient survival, graft survival, and incidence of biopsy-proven acute rejection were 98%, 80%, and 10%, respectively, in the CI-sparing group and 100%, 89%, and 7%, respectively, in the CI-free group. Three-month protocol biopsies were performed in 41% (17/41) and 67% (20/29) of the subjects in the CI-sparing and CI-free groups, respectively. Subclinical rejection was detected in 6% (1/17) and 15% (3/20) of the subjects in the CI-sparing and CI-free groups, respectively. Histologic evidence of chronic allograft nephropathy was more prevalent in the CI-sparing group. At 1 year, the mean estimated creatinine clearance was higher in the CI-free group than in the CI-sparing group (72.4 +/-20.0 mL/min vs. 50.5 +/-20.8 mL/min, P <0.01). The two regimens had similar toxicity profiles (hospital readmission, infection, wound complications, and metabolic complications). CONCLUSIONS: Both sirolimus-based CI-sparing and CI-free regimens are safe and effective in a population with high immunologic risk. The CI-free regimen is associated with better renal function at 1 year post-transplant. Long-term follow-up will aid in determining the risk and benefit ratio of these regimens.