The hemolytic component of cancer anemia: effects of osmotic and metabolic stress on the erythrocytes of rats bearing multifocal inoculations of the Walker 256 tumor.

Cancer anemia is classified as an anemia of chronic diseases, although it is sometimes the first symptom of cancer. Cancer anemia includes a hemolytic component, important in the terminal stage when even transfused cells are rapidly destroyed. The presence of a chronic component and the terminal complications of the illness limit studies of the hemolytic component. A multifocal model of tumor growth was used here to simulate the terminal metastatic dissemination stage (several simultaneous inoculations of Walker 256 cells). The hemolytic component of anemia began 3-4 days after inoculation in 100% of the rats and progressed rapidly thereafter: Hb levels dropped from 14.9 +/- 0.02 to 8.7 +/- 0.06 from days 7 to 11 ( approximately 5 times the physiologically normal rate in rats) in the absence of bleeding. The development of anemia was correlated (r2 = 0.86) with the development of other systemic effects such as anorexia. There was a significant decrease in the osmotic fragility of circulating erythrocytes: the NaCl concentration causing 50% lysis was reduced from 4.52 +/- 0.06 to 4.10 +/- 0.01 (P<0.01) on day 7, indicating a reduction in erythrocyte volume. However, with mild metabolic stress (4-h incubation at 37oC), the erythrocytes showed a greater increase in osmotic fragility than the controls, suggesting marked alteration of erythrocyte homeostasis. These effects may be due to primary plasma membrane alterations (transport and/or permeability) and/or may be secondary to metabolic changes. This multifocal model is adequate for studying the hemolytic component of cancer anemia since it is rapid, highly reproducible and causes minimal animal suffering.

[Dengue fever: a post-epidemic sero-epidemiological survey in an urban area setting at a northwestern county of São Paulo State, Brazil]. / Dengue: inquérito sorológico pós-epidêmico em zona urbana do Estado de São Paulo (Brasil).

OBJECTIVE: The objective of this study was to evaluate the real size of the epidemics registered in the urban area of the county of Santa Bárbara D'Oeste, SP, Brazil, from April to June, 1995. The measurement of the epidemiological validity of the official surveillance system criteria and its positive predicted value were adopted as specific goals. METHODS: A sero-epidemiological survey was carried out over a sample of 1,113 sera from citizens of Santa Barbara D'Oeste, through a systematic random sampling of houses, five months after the end of the epidemics. Infection rates were compared with the infestation indexes by Aedes aegipty and the notified cases amongst the county sections. The importance of submitting patients with clinical suspicion of dengue to laboratory tests was discussed. RESULTS AND DISCUSSION: It was found that infection rates by dengue virus varied in the same direction and proportion as the presence of Aedes aegipty larvae reported by the "Breteau Index", as well as the number of cases reported by the official notifiable diseases surveillance system during the epidemics. A prevalence of 630 by 100 thousand inhabitants was found, a 15-fold rate when compared to the laboratory positive sera from cases detected by the surveillance system during the epidemics. A retrospective comparison with the surveillance reports, using serological results as a gold standard, also showed that the majority of dengue specific serum-positive individuals were not detected during the epidemics, otherwise cases that did not present serological reaction were notified exhibiting a low positive predictive value of clinical diagnosis (15,6).

The hemolytic component of cancer anemia: effects of osmotic and metabolic stress on the erythrocytes of rats bearing multifocal inoculations of the Walker 256 tumor

Cancer anemia is classified as an anemia of chronic diseases, although it is sometimes the first symptom of cancer. Cancer anemia includes a hemolytic component, important in the terminal stage when even transfused cells are rapidly destroyed. The presence of a chronic component and the terminal complications of the illness limit studies of the hemolytic component. A multifocal model of tumor growth was used here to simulate the terminal metastatic dissemination stage (several simultaneous inoculations of Walker 256 cells). The hemolytic component of anemia began 3-4 days after inoculation in 100 percent of the rats and progressed rapidly thereafter: Hb levels dropped from 14.9 +/- 0.02 to 8.7 +/- 0.06 from days 7 to 11 (~5 times the physiologically normal rate in rats) in the absence of bleeding. The development of anemia was correlated (r2 = 0.86) with the development of other systemic effects such as anorexia. There was a significant decrease in the osmotic fragility of circulating erythrocytes: the NaCl concentration causing 50 percent lysis was reduced from 4.52 +/- 0.06 to 4.10 +/- 0.01 (P<0.01) on day 7, indicating a reduction in erythrocyte volume. However, with mild metabolic stress (4-h incubation at 37§C), the erythrocytes showed a greater increase in osmotic fragility than the controls, suggesting marked alteration of erythrocyte homeostasis. These effects may be due to primary plasma membrane alterations (transport and/or permeability) and/or may be secondary to metabolic changes. This multifocal model is adequate for studying the hemolytic component of cancer anemia since it is rapid, highly reproducible and causes minimal animal suffering.