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Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that regulates renal phosphate reabsorption and vitamin D synthesis in renal proximal tubules. High circulating FGF23 levels are associated with increased mortality in patients with chronic kidney disease and those on dialysis. Current data also suggest higher circulating levels of FGF23 are associated with cardiovascular mortality, vascular calcification, and left ventricular hypertrophy; however, evidence on the role of FGF23 in patients on dialysis is incomplete, and some of the data, especially those on cardiovascular disease (CVD), are controversial. This study aimed to evaluate factors associated with FGF23 in hemodialysis patients with or without CVD. Randomly selected 76 patients on maintenance hemodialysis at a single hemodialysis center were enrolled. After the exclusion of eight patients with extremely outlying FGF23 levels, 68 patients, including 48 males and 46 patients with a CVD history, were included in the study. The mean age was 64.4 ± 12.1 years, and the mean dialysis duration was 12.7 ± 7.1 years. Dialysis duration, time-averaged concentration of urea (TAC-urea), ultrafiltration rate (UFR), blood pressure during hemodialysis session, laboratory data, and echocardiographic parameters including interventricular septum thickness (IVST), left ventricular mass indices (LVMI), and ejection fraction were included in univariate and multivariate analyses. The median lgFGF23 levels in the overall cohort and in those with and without CVD were 2.14 (interquartile range, IQR - 0.43 to - 4.23), 2.01 (- 0.52 to 4.12), and 2.59 (0.07 to 4.32), respectively, and there was no difference between the patients with and without CVD (p = 0.14). The univariate analysis revealed that FGF23 was significantly associated with age (r =  - 0.12, p < 0.01), duration of hemodialysis (r =  - 0.11, p < 0.01), TAC-urea (r = 0.29, p = 0.01), UFR (r = 0.26, p = 0.04), alkaline phosphatase (ALP; r =  - 0.27, p = 0.03), corrected serum calcium (cCa; r = 0.32, p < 0.01), serum phosphate (iP, r = 0.57, p < 0.01), intact parathyroid hormone (iPTH; r = 0.38, p < 0.01), IVST (r = 0.30, p = 0.01), and LVMI (r = 0.26, p = 0.04). In multivariate regression analysis, FGF23 was significantly associated with cCa (F = 25.6, p < 0.01), iP (F = 22.5, p < 0.01), iPTH (F = 19.2, p < 0.01), ALP (F = 5.34, p = 0.03), and UFR (F = 3.94, p = 0.05). In addition, the univariate analysis after the categorization of patients according to CVD indicated that FGF23 was significantly associated with cCa (r = 0.34, p = 0.02), iP (r = 0.41, p < 0.01), iPTH (r = 0.39, p = 0.01), and TAC-urea (r = 0.45, p < 0.01) in patients with CVD, whereas only IVST (r = 0.53, p = 0.04) was associated with FGF23 in those without CVD. FGF23 levels in hemodialysis patients were extremely high and associated not only with mineral bone disease-related factors but also with UFR. Additionally, dialysis efficacy might be associated with lower FGF23 levels in patients with CVD.

Antihistamines are widely used to treat pruritus in patients receiving hemodialysis. In a previous cross-sectional study, we reported an association between antihistamine use and the absence of eccentric cardiac hypertrophy in patients receiving hemodialysis. Therefore, in this study, we sought to evaluate the efficacy of antihistamines on all-cause and cardiovascular mortality in patients receiving hemodialysis according to our outpatient dialysis database. We used a propensity score matching method. Among the 389 patients receiving hemodialysis according to our database, we extracted those taking antihistamines and matched them with patients not taking antihistamines using propensity scores based on 38 variables. All-cause mortality and cardiovascular mortality were estimated by the Kaplan-Meier method, and a log-rank test was used to examine the differences between the survival curves. We included 154 patients, or 77 matched pairs, from the entire cohort (c-statistic = 0.78, p < 0.0001). There were no differences in any background factor between the antihistamine and non-antihistamine group. During the mean observational period of 5.4 years, 50 patients died, and the all-cause mortality rate was 27.3% (21 patients) in the antihistamine group and 37.3% (29 patients) in the non-antihistamine group (p = 0.0314). The cardiovascular mortality rate was 16.9% (13 patients) in the antihistamine group and 25.9% (20 patients) in the non-antihistamine group (p = 0.0417). The results of this study suggest that all-cause and cardiovascular mortality improved with antihistamine use in patients receiving hemodialysis. However, the clinical efficacy of antihistamines needs to be confirmed in a prospective randomized study in the future.

One type of maturity-onset diabetes of the young (MODY2) is caused by mutations in the glucokinase gene, a key glycolytic enzyme in the beta cell and liver. Glucose fails to stimulate insulin secretion in mice in which the glucokinase gene has been selectively knocked out in the beta cell. We tested the hypothesis that this effect results from defective metabolic regulation of beta cell ATP-sensitive potassium (K(ATP)) channels. Glucose had little effect on K(ATP) currents in homozygous (-/-) mice but inhibited K(ATP) currents in wild-type (+/+) and heterozygous (+/-) mice with EC50 of 3.2 mM and 5.5 mM, respectively, in newborn animals, and of 4.7 mM and 9.9 mM, respectively, in 1.5-year-old mice. Glucose (20 mmol/l) did not affect the resting membrane potential of -/- beta cells but depolarised wild-type and + /- beta cells and induced electrical activity. In contrast, 20 mmol/l ketoisocaproic acid or 0.5 mmol/ l tolbutamide depolarised all three types of beta-cell. These results support the idea that defective glycolytic metabolism, produced by a loss (-/- mice) or reduction (+/- mice) of glucokinase activity, leads to defective K(ATP) channel regulation and thereby to the selective loss, or reduction, of glucose-induced insulin secretion.

Insulin secretion is stimulated by glucose, hormones and neurotransmitters. Both activation of a non-selective cation current and activation of a Ca2+ current in response to depletion of intracellular Ca2+ stores have been suggested to play a role in this stimulation. The properties of these currents resemble those reported for the Drosophila genes trp and trpl. Using the reverse transcription polymerase chain reaction and Northern blot analysis we found that of the six mammalian trp-related genes (trp1-6), only trp1 was expressed at high levels in the mouse insulinoma cell line MIN6. We cloned the murine homologue of human trp1 from MIN6 cells and identified four variants (alpha, beta, gamma and delta), generated by alternative splicing near the N-terminus of the protein. In vitro translation showed that only the alpha and beta splice variants are efficiently expressed. The beta variant is the dominant form in MIN6 cells (and probably in mouse pancreatic islets), whereas the alpha variant is the major type in the mouse brain. The beta variant showed 99% identity to the human homologue at the amino acid level.

The ATP-sensitive K-channel plays a central role in insulin release from pancreatic beta cells. This channel consists of two subunits: a sulphonyl-urea receptor, SUR1, and an inwardly rectifying K-channel subunit, Kir6.2. We screened 135 white Caucasian patients with non-insulin-dependent diabetes mellitus (NIDDM) and 90 non-diabetic subjects for mutations in the Kir6.2 gene by single-stranded conformational polymorphism (SSCP) analysis. We identified one silent mutation (A190A) and four missense mutations (E23K, L270V, I337V and S385C) in normal and diabetic individuals. In a single diabetic subject, we identified a two-amino acid insertion (380KP). We also screened 39 Afro-Caribbean diabetic subjects and identified one additional missense (L355P) and one more silent (S363S) mutation. The E23K and I337V variants were completely linked. The common variants (E23K, 1337V and L270V) were found with similar frequency in diabetic and normal subjects. Diabetic subjects with the variants responded normally to sulphonylurea therapy. When mutant Kir6.2 subunits were coexpressed with SUR1 in Xenopus oocytes, there was no difference in the sensitivity of the whole-cell currents to metabolic inhibition or to the sulphonylurea tolbutamide. We therefore conclude that mutations in Kir6.2 are unlikely to be a major cause of NIDDM.

Mitochondrial DNA is exclusively maternally inherited. We recently found the prevalence of diabetic patients with an A to G transition at position 3243 of leucine tRNA (3243 base pair (bp) mutation) to be nearly 1% in randomly selected Japanese subjects. Here, we report the higher prevalence of diabetic patients with the 3243 bp mutation in a specific Japanese population of women attending a diabetic pregnancy clinic. Of 102 patients with non-insulin-dependent diabetes mellitus 6 (5.9%) were positive for the mutation, 1 (8.3%) of 12 patients with gestational diabetes and 2 (5.9%) out of 34 borderline diabetic patients. In contrast, none of 64 patients (0%) with insulin-dependent diabetes mellitus had the 3243 bp mutation. Moreover, there was a difference in the prevalence of spontaneous abortions between patients with and without this mutation (27.3 vs 12.4%). Among nine probands with the mutation, four had a history of one spontaneous abortion (p = 0.0518) and two had a history of two abortions (p = 0.0479). Two probands had a spontaneous abortion even while under strict diabetic metabolic control. The 3243 bp mutation thus may cause spontaneous abortion during pregnancy.

We analyzed single-stranded conformational polymorphisms to screen for mutations and polymorphisms in the insulin receptor gene in subjects with or without insulin resistance. Using this new technique, we demonstrated the existence of mutations in the insulin receptor gene which we had identified previously. In addition, a new mutation was found in exon 20 of the insulin receptor gene in a patient with moderate insulin resistance associated with morbid obesity, acanthosis nigricans, and polycystic ovary syndrome. The patient was heterozygous for a mutation substituting Leu (CTG) for Pro (CCG) at codon 1178. Pro1178 is a part of a characteristic sequence motif (D1150 F1151 G1152---A1177 P1178 E1179) common to many protein kinases. Analysis of single-stranded conformational polymorphisms was also used to estimate the frequency of a polymorphism at codon 1058. The two codons CAC (1058 His) and CAT (1058 His) both had a prevalence of 50% in 30 Japanese subjects. These data demonstrate that analysis of single-stranded conformational polymorphisms is a simple and sensitive screening method for mutations and polymorphisms in the insulin receptor gene in subjects with or without insulin resistance. Identification of a mutation in the insulin receptor gene in a patient with a moderate degree of insulin resistance associated with morbid obesity suggests that insulin receptor mutations may exist in patients with Type 2 (non-insulin-dependent) diabetes mellitus associated with a moderate degree of insulin resistance.

An allergic reaction to peplomycin was observed in a patient with cervical uterine cancer who had previously been treated with peplomycin. A positive Prausnitz-Küstner test and its elimination after heat treatment of the serum showed the production of anti-peplomycin IgE antibody. Peplomycin was coupled to a paper disc and a sensitive radioallergosorbent test for peplomycin was developed to quantitate the antibody. Patient serum IgE and IgG were purified by DE52 column chromatography; the IgE fraction contained binding activity to peplomycin. A competition test revealed that the antibody bound to both peplomycin and bleomycin. DNA, RNA, and mononucleotides had no effect on antibody binding, but the antibody inhibited peplomycin's activity.