Substitution of Acetic Acid for Hydrochloric Acid in the BicarbonateBuffered Dialysate

Abstract: In a multicenter study including 5 dialysis units, blood acetate changes during 4 h dialysis sessions in 141 patients treated with a 4 mM acetate-containing bicarbonate dialysate (ABD) were evaluated and compared to the values of 114 patients using an acetate-free bicarbonate dialysate (AFD). Acetate-free bicarbonate dialysate was delivered by a dialysis machine from the mixing with water for dialysis of a 1/26.2 bicarbonate concentrate, and a 1/35 acid-concentrate in which acetic acid was substituted for hydrochloric acid (Soludia, Fourquevaux, France). This new type of dialysate was routinely in use for 3 years on average (range, from 2 to 5 years). All patients fasted before and during dialysis. Blood samples were withdrawn at the start and at the end of dialysis sessions. The acetate plasma concentration was determined using the acetyl-CoA synthetase enzymatic method (Boehringer, Manheim, Germany). In patients treated with ABD whose predialysis blood acetate levels were in the physiologic range of ≤100 μM (n = 113), the acetate plasma concentration increased from a predialysis mean value of 22 ± 3 μM to a postdialysis mean value of 222 ± 11 μM in 88 patients (78% of patients) whereas the acetate plasma concentration changes remained in the range of physiologic values from 21 ± 6 to 58 ± 7 μM in the other 25 patients. In contrast, patients treated with AFD whose predialysis blood acetate levels were in the physiologic range (n = 108), acetate plasma concentration increased from a predialysis mean value of 49 ± 6 μM to 160 ± 19 μM in only 13 patients (12% of patients) whereas acetate plasma concentration changes remained in the range of physiologic values of 23 ± 2 to 41 ± 3 μM in most of the patients of this group. In this study, a significant number of patients, whether receiving standard or acetate-free bicarbonate dialysates, exhibited an extremely high acetate plasma concentration at the start of the dialysis session. Hyperacetatemia was controlled with AFD in patients whose predialysis acetate plasma concentration of 316 ± 82 decreased to 55 ± 23 μM (n = 6) at the end of the dialysis session whereas the acetate plasma concentration remained high when the predialysis concentration was 580 ± 76 μM, with a postdialysis concentration of 233 ± 39 μM (n = 28). It is concluded that in patients whose predialysis blood acetate levels were in the physiologic range, acetate-containing bicarbonate dialysate induces hyperacetatemia whereas postdialysis blood acetate remains in the normal range in such dialysis patients treated with acetate-free dialysate. Chronic hyperacetatemia, which could be found in dialysis patients, is well controlled by dialysis using an acetate-free dialysate.     

Aggregation of rhDNase Occurred During the Compression of KBr Pellets Used for FTIR Spectroscopy

Purpose. To determine if a protein changes when it is compressed into a KBr pellet for FTIR spectroscopy measurement in the solid state, using recombinant human deoxyribonuclease I (rhDNase) as an example. Methods. Lyophilized rhDNase with KBr compressed at different pressures were analyzed by FTIR spectroscopy, size exclusion HPLC and enzymatic activity assay. Different protein/KBr weight ratios and residual water contents were studied for their possible effects on aggregation. Results. Depending on the pressure, a loss of enzymatic activity accompanied by an increase in soluble high molecular weight aggregates of the protein (up to ~15%) was demonstrated. Aggregation was reduced to less than 5% by a suitable dilution of the protein in KBr (1 in 1000). In contrast, water content variability (1–11 wt. %) did not affect aggregation. Conclusions. The findings emphasize the importance to examine for protein integrity when using the KBr method for FTIR sample preparation. Protein aggregation may be minimized by optimizing the sample preparation condition such as changing the protein/KBr weight ratio.     

Impaired release of interleukin-6 from human osteoblastic cells in the uraemic milieu.

BACKGROUND: Osteoblast-derived interleukin-6 (IL-6) affects bone metabolism and is linked with a number of pathological states characterized by increased bone resorption, including osteoporosis and renal osteodystrophy. To examine the possibility that uraemia directly influences the release of this cytokine in bone, we have investigated the effect of human uraemic serum on the release of IL-6 from human osteoblast-like cells. METHODS: Individual serum samples collected from healthy male volunteers or male haemodialysis patients prior to and during a dialysis treatment were assayed for IL-6, interleukin-1beta (IL-1beta) and soluble IL-6 receptor (sIL-6R) using specific enzyme-linked immunosorbent assays. MG-63 and SaOS-2 cells were cultured in media containing pooled sera from both groups and alongside matching charcoal-stripped sera. IL-6 concentrations were determined in harvested cell supernatants after 24 h. In further experiments, media containing individual sera obtained from five patients at regular intervals during their haemodialysis treatment were incubated with MG-63 cells to determine the effects of the dialysis process on IL-6 secretion. RESULTS: Haemodialysis patients had significantly higher (n = 10, P < 0.001) circulating concentrations of IL-6 (7.0 +/- 1.6 pg/ml) than normal subjects (0.4 +/- 0.1 pg/ml), but there were no significant differences in the concentrations of either IL-1beta or sIL-6R. These serum concentrations did not change significantly during 80 min of dialysis. IL-6 release by MG-63 cells incubated with charcoal-stripped serum from normal or from uraemic subjects was similar. Incubation with untreated sera from normal subjects increased IL-6 release by approximately 6-fold above the charcoal-stripped control, whereas sera from uraemic subjects increased IL-6 release by only approximately 2- to 3-fold (normal vs uraemic of 6878 +/- 595 and 2579 +/- 169 pg/ml, respectively, P < 0.001). Similar results were seen with SaOS-2 cells. Haemodialysis did not restore the capacity of uraemic serum to augment IL-6 release to the same degree as normal serum. CONCLUSIONS: These data show that the augmentation of IL-6 release from human osteoblastic cells after incubation with normal serum is greater than after uraemic serum. This may indicate the presence of an inhibitor of IL-6 release in uraemic serum that is involved in the deranged bone turnover of uraemic patients.     

Chelators at the cancer coalface: desferrioxamine to Triapine and beyond.

The importance of iron and copper in cancer biology has been well established. Iron plays a fundamental role in cellular proliferation and copper has been shown to be a significant cofactor for angiogenesis. Early observations with the chelator used for the treatment of iron overload, desferrioxamine, showed that it had promise as an anticancer agent. These results sparked great interest in the possibility of developing more effective iron chelators for cancer therapy. The recent entry into clinical trials of the iron-binding drug, Triapine, provides evidence of the potential of this antitumor strategy. Likewise, chelators originally designed to treat disorders of copper overload, such as penicillamine, trientine, and tetrathiomolybdate, have also emerged as potential anticancer drugs, as they are able to target the key angiogenic cofactor, copper. In this review, we will discuss the development of these and other chelators that show potential as anticancer agents.     

Nil-8 conditioned medium stimulates growth of human mammary epithelial cells

Summary The growth of human mammary epithelium cultured from benign tumors or normal breast is stimulated by a medium conditioned by Nil-8 cells; the conditioned medium acts synergistically with epidermal growth factor in stimulating growth. Conditions for optimal harvesting of the medium are described, logether with some properties of the conditioned medium. Address for reprints: Ian S. Fentiman, Breast Unit, Guy's Hospital, London SE 1, UK.     

Fetal cystic malformations of the posterior fossa in the first trimester of pregnancy

Diagnosis of abnormalities of the posterior fossa, such as Dandy-Walker malformation, can be assessed during the first trimester of pregnancy by ultrasonography. We report on 5 cases of posterior fossa abnormalities, 4 Dandy-Walker malformations and 1 Dandy-Walker variant, diagnosed during the first trimester of pregnancy by ultrasound examination. All cases were confirmed later during the pregnancy by further ultrasound examinations or by postmortem examination when parents elected for termination of pregnancy. Two of our Dandy-Walker malformation cases were siblings from consanguineous parents and had a Meckel syndrome variant associated with the posterior fossa malformation, multicystic kidneys and hepatic fibrosis. We believe first trimester diagnosis of Dandy-Walker complex is possible, but needs to be confirmed later during the pregnancy and should prompt a detailed survey for other abnormalities.