Quality control of blood irradiation with a teletherapy unit: damage to stored red blood cells after cobalt-60 gamma irradiation.

BACKGROUND: Previous publications have documented the damage caused to red blood cells (RBCs) irradiated with X-rays produced by a linear accelerator and with gamma rays derived from a 137Cs source. The biologic effects on RBCs of gamma rays from a 60Co source, however, have not been characterized. STUDY DESIGN AND METHODS: This study investigated the effect of 3000 and 4000 cGy on the in vitro properties of RBCs preserved with preservative solution and irradiated with a cobalt teletherapy unit. A thermal device equipped with a data acquisition system was used to maintain and monitor the blood temperature during irradiation. The device was rotated at 2 r.p.m. in the irradiation beam by means of an automated system. The spatial distribution of the absorbed dose over the irradiated volume was obtained with phantom and thermoluminescent dosimeters (TLDs). Levels of Hb, K+, and Cl(-) were assessed by spectrophotometric techniques over a period of 45 days. The change in the topology of the RBC membrane was investigated by flow cytometry. RESULTS: Irradiation caused significant changes in the extracellular levels of K+ and Hb and in the organizational structure of the phospholipid bilayer of the RBC membrane. Blood temperature ranged from 2 to 4 degrees C during irradiation. Rotation at 2 r.p.m. distributed the dose homogeneously (92%-104%) and did not damage the RBCs. CONCLUSIONS: The method used to store the blood bags during irradiation guaranteed that all damage caused to the cells was exclusively due to the action of radiation at the doses applied. It was demonstrated that prolonged storage of 60Co-irradiated RBCs results in loss of membrane phospholipids asymmetry, exposing phosphatidylserine (PS) on the cells' surface with a time and dose dependence, which can reduce the in vivo recovery of these cells. A time- and dose-dependence effect on the extracellular K+ and plasma-free Hb levels was also observed. The magnitude of all these effects, however, seems not to be clinically important and can support the storage of irradiated RBC units for at last 28 days.

[Levels of contaminant zinc in solutions routinely used in rehydration and/or parenteral feeding]. / Conteúdo do zinco contaminante nas soluções rotineiramente utilizadas em hidratação e/ou alimentação parenteral.

With the objective to evaluate the zinc needs of children submitted to rehydration and/or parenteral nutrition, the content of contaminating zinc was determined in intravenous solutions utilized at University Hospital of Ribeirão Preto, SP, Brazil. Zinc was measured in 40 bottles containing deionized water and submitted to the routine treatment for industrialization of serum for parenteral use, according to the standards of the University Hospital of Ribeirão Preto, Industrial Pharmacy. The effect of the sealing material employed (polished red stopper and unpolished black stopper) was observed, as well as time of contact between the solutions and rubber stoppers and latex slides, and the method of bottle conditioning (vertical or horizontal position) which permits contact of the solutions with the rubber stoppers. The gluco-saline solutions prepared in our Hospital and stored in glass bottles with unpolished black rubber stoppers and latex slide showed substantial zinc levels (1,220 to 4,860 micrograms/ml, n = 30). The same solutions kept in glass vials or plastic bottles were zinc free. The highest zinc levels were observed in the amino acid solutions placed in sealed bottles with unpolished black rubber stoppers (11,690 to 24,310 micrograms/ml, n = 20). It is important to be aware of these contaminating zinc levels to provide proper treatment involving this micronutrient.