ABSTRACT
The effects of the timing of first feeding on the point-of-no-return (PNR) and growth of laboratory reared silver catfish Rhamdia voulezi larvae were studied. The experiment began immediately after the complete absorption of the yolk sac, 3 days after hatching (DAH). The food was provided for the first time on 3rd, 4th, 5th, 6th, 7th, 8th, and 9th DAH. Zooplankton and newly-hatched Artemia spp. were used to feed the larvae. To evaluate the effect of food deprivation on growth, the standard length and weight of 594 larvae were assessed. Larval growth was significantly affected by the time of first exogenous feeding. The larvae fed from 3rd to 5th DAH showed a significantly higher development than those fed from 6th DAH. The larvae reached the PNR on 6th DAH. Survival and larval growth strongly depended on the timing of initial feeding. In order to avoid potential mortality by starvation and obtain good growth, the silver catfish larvae R. voulezi must establish successful initial feeding within 5 days after hatching.(AU)
Os efeitos do tempo da alimentação inicial sobre o ponto de não retorno (PNR) e o crescimento de larvas de jundiá Rhamdia voulezi foram estudados em condições laboratoriais. O experimento foi iniciado imediatamente após a completa absorção do saco vitelínico, 3 dias após a eclosão (DAE). O alimento foi fornecido pela primeira vez no 3o, 4o, 5o, 6o, 7o, 8o e 9o DAE. Zooplâncton e Artemia spp. recém-eclodida foram usados para a alimentação das larvas. Para avaliar os efeitos da privação alimentar sobre o crescimento, o comprimento padrão e peso de 594 larvas foram analisados. O crescimento larval foi significativamente afetado pelo tempo da primeira alimentação exógena. As larvas que receberam alimento do 3 o ao 5 o DAE apresentaram desenvolvimento significativamente maior que aquelas alimentadas mais tardiamente, a partir do 6 o DAE. As larvas alcançaram o PNR no 6 o DAE. A sobrevivência e o crescimento das larvas dependem do momento da alimentação inicial. Para evitar a mortalidade em massa e obter bom crescimento, as larvas de R. voulezi precisam estabelecer com sucesso a alimentação inicial até o 5 o dia após a eclosão.(AU)
Subject(s)
Catfishes/abnormalities , Catfishes/growth & development , Catfishes/metabolism , Animal Feed/analysis , Larva/growth & developmentABSTRACT
BACKGOUND: The progression rate of IgA nephropathy is known to be variable. We tried to draw an equation that can predict the interval till end stage renal disease (ESRD). METHODS: We retrospectively checked the risk factors of the progression such as demographic, clinical, laboratory, and histologic data by using simple linear regression in eighty eight (M:F=53:35) patients with biopsy-proven IgA nephropathy from Oct 1994 to Aug 2004. By multiple linear regression, a semiquantitative equation estimating the rate of progression was developed. We also evaluated whether there is a "point of no return" that progresses to ESRD which was shown by D'Amico ('93) and Scholl ('99) by receiver operating characteristic (ROC) curve analysis. RESULTS: Mean age and follow-up period were 34.1+/-13.6 years and 55.7+/-31.4 months. Among the risk factors, spot urine protein to creatinine ratio and mean arterial pressure during the follow-up period were significantly associated with the rate of progression (p<0.05). A semiquantitative equation estimating the rate of progression using the two factors was developed as follow. (delta)CCr=2.206-(0.128 x PCR(follow-up))-(0.023 x MAP(follow-up)) (MAPfollow-up:mean arterial pressure; regression coefficient=-0.023, PCRfollow-up:spot urine protein/creatinine; regression coefficient=-0.128). By ROC curve analysis, all patients with maximum serum creatinine over 4.1 mg/ dL during follow-up were found to progress to ESRD. CONCLUSION: We conclude that in Korean IgA nephropathy patients we could predict the rate of decline in renal function for individual patients semiquantitatively and we could confirm the existence of a "point of no return" during the course of IgA nephropathy.