Kinetics of Serum Carnitine Fractions in Patients with Chronic Kidney Disease Not on Dialysis.

BACKGROUND: Carnitine plays a pivotal role in energy synthesis through ß-oxidation in mitochondria. Serum and tissue levels of free carnitine are significantly decreased in dialysis patients, whereas acylcarnitine levels are increased. However, the precise kinetics and fate of carnitine fractions in chronic kidney disease (CKD) patients who are not on dialysis have not been clarified. This study aims to determine the kinetics of serum carnitine fractions in patients who were not on dialysis. METHODS: Seventy-five CKD patients not on dialysis were recruited in this study. Serum and urinary carnitine fraction levels were measured to evaluate the kinetics and regulation of serum carnitine fractions. Carnitine fractions were measured by the enzymatic cycling method. RESULTS: Total and free serum carnitine levels did not change with progression of CKD, whereas acylcarnitine levels and the acyl/free carnitine ratio significantly increased. Serum acylcarnitine levels were inversely associated with estimated glomerular filtration rate (r2 = 0.239, p < 0.001), but free carnitine levels were not. Serum free carnitine levels were positively associated with urinary free carnitine excretion (r2 = 0.214, p < 0.001), but serum acylcarnitine levels were not. Multiple stepwise regression analysis revealed that urinary free carnitine excretion and blood urea nitrogen were independent determinants of serum free carnitine and acylcarnitine levels, respectively. CONCLUSIONS: The present study demonstrated that serum acylcarnitine levels increased with renal dysfunction independent of urinary excretion levels. Serum free carnitine was not affected by renal function in CKD patients who were not on dialysis.

Effects of Reducing L-Carnitine Supplementation on Carnitine Kinetics and Cardiac Function in Hemodialysis Patients: A Multicenter, Single-Blind, Placebo-Controlled, Randomized Clinical Trial.

L-carnitine (LC) supplementation improves cardiac function in hemodialysis (HD) patients. However, whether reducing LC supplementation affects carnitine kinetics and cardiac function in HD patients treated with LC remains unclear. Fifty-nine HD patients previously treated with intravenous LC 1000 mg per HD session (three times weekly) were allocated to three groups: LC injection three times weekly, once weekly, and placebo, and prospectively followed up for six months. Carnitine fractions were assessed by enzyme cycling methods. Plasma and red blood cell (RBC) acylcarnitines were profiled using tandem mass spectrometry. Cardiac function was evaluated using echocardiography and plasma B-type natriuretic peptide (BNP) levels. Reducing LC administration to once weekly significantly decreased plasma carnitine fractions and RBC-free carnitine levels during the study period, which were further decreased in the placebo group (p < 0.001). Plasma BNP levels were significantly elevated in the placebo group (p = 0.03). Furthermore, changes in RBC (C16 + C18:1)/C2 acylcarnitine ratio were positively correlated with changes in plasma BNP levels (ß = 0.389, p = 0.005). Reducing LC administration for six months significantly decreased both plasma and RBC carnitine levels, while the full termination of LC increased plasma BNP levels; however, it did not influence cardiac function in HD patients.

Enhanced IgG1 production by overexpression of nuclear factor kappa B inhibitor zeta (NFKBIZ) in Chinese hamster ovary cells.

Several engineering strategies have been employed to improve the production of therapeutic recombinant proteins in Chinese hamster ovary (CHO) cell lines. We have focused on unfolded protein response-based engineering and reported that ATF4 overexpression increases protein production. In this study, transcriptome analysis of ATF4-overexpressed CHO cells was performed using high-coverage expression profiling, to search for another key factor contributing to recombinant protein production. We observed the upregulated expression of transcription factor, nuclear factor (NF)-kappa-B inhibitor zeta (NFKBIZ or Iκbζ), in ATF4-overexpressed cells. A total of 1917 bp of CHO NFKBIZ cDNA was cloned, and two stable cell lines overexpressing NFKBIZ were constructed. We investigated the effects of NFKBIZ on IgG1 production in CHO cells. Although the two stable cell lines, NFKBIZ-A and -B, had the opposite phenotypes in cell growth, the specific IgG1 production rate of both cell lines was enhanced by 1.2-1.4-fold. In the NFKBIZ-A cell line, the synergistic effect between enhanced viable cell density and improved specific IgG1 production rate brought about a large increase in the final IgG1 titer. Luciferase-based NF-κB signaling assay results suggest that altered p50/p50 signaling seems to be due to the opposite phenotypes in cell growth. No difference was observed in the translational levels and intracellular assembly states of IgG1 between mock and two NFKBIZ cell lines, indicating that the secretion machinery of correctly folded IgG1 was enhanced in NFKBIZ-overexpressing cell lines.

Unusually high levels of serum p53 antibody in recurrent gastric cancer.

Serum tumor markers in patients with cancer assist with establishing diagnosis, estimating prognosis, monitoring treatment, and detecting tumor recurrence. Changes in the p53 tumor suppressor gene are the most common genetic abnormalities in many different human malignancies. Several studies have demonstrated that serum p53 antibodies (S-p53Ab) comprise an early marker of malignant disease, a marker for treatment effects and a prognostic factor for patients with several types of tumors. We recently reported that S-p53Ab is useful for patients with gastric cancer. We describe a rare situation in which unusually high serum p53 antibodies helped to detect recurrent gastric cancer in the small intestine after gastrectomy. Further studies are required to gain a more precise understanding of the clinical impact of S-p53Ab titer monitoring in gastric cancer.