Pure laparoscopic pancreas parenchymal dissection using CUSA for distal pancreatectomy

Although stapler dissection and closure is commonly used for laparoscopic distal pancreatectomy (LDP), it is risky in patients with thick pancreatic parenchyma or titanium allergy. We performed laparoscopic pancreatic parenchymal dissection with cavitron ultrasonic surgical aspirator (CUSA) successfully in a patient with titanium allergy. Slinging the pancreas with nylon tape delineates the surgical plane. Pancreatic parenchyma was transected by CUSA in an almost bloodless field. Pancreatic duct branches and vessels were adequately exposed and dissected with a vessel sealing system. The main pancreatic duct was closed with Hem-O-lock. CUSA is an alternative to stapler dissection during LDP in select patients.     

KATP channel interaction with adenine nucleotides

ATP-sensitive potassium (K(ATP)) channels are regulated by adenine nucleotides to convert changes in cellular metabolic levels into membrane excitability. Hence, elucidation of interaction of SUR and Kir6.x with adenine nucleotides is an important issue to understand the molecular mechanisms underlying the metabolic regulation of the K(ATP) channels. We analyzed direct interactions with adenine nucleotides of each subunit of K(ATP) channels. Kir6.2 binds adenine nucleotides in a Mg(2+)-independent manner. SUR has two NBFs which are not equivalent: NBF1 is a Mg(2+)-independent high affinity nucleotide binding site, whereas NBF2 is a Mg-dependent low affinity site. Although SUR has ATPase activity at NBF2, it is not used to transport substrates against the concentration gradient unlike other ABC proteins. The ATPase cycle at NBF2 serves as a sensor of cellular metabolism. This may explain the low ATP hydrolysis rate compared to other ABC proteins. Based on studies of photoaffinity labeling, a model of K(ATP) channel regulation is proposed, in which K(ATP) channel activity is regulated by SUR via monitoring the intracellular MgADP concentration. K(ATP) channel activation is expected to be induced by the cooperative interaction of ATP binding at NBF1 and MgADP binding at NBF2.     

Phase transformation of a new generation yttria-stabilized zirconia femoral head after total hip arthroplasty

We examined a new-generation yttria-stabilized zirconia head manufactured by NGK 1 year after total hip arthroplasty. Monoclinic content of the retrieved head was twice that of the unused head at the pole and equator. A fourfold increase in monoclinic content was observed at 5 mm below the equator. Transformation from the tetragonal phase to the monoclinic phase occurred in the new generation zirconia with alumina doping within a relatively short period in vivo.     

Application of a physiologically based pharmacokinetic model for the prediction of mirabegron plasma concentrations in a population with severe renal impairment

We previously verified a physiologically based pharmacokinetic (PBPK) model for mirabegron in healthy subjects using the Simcyp Simulator by incorporating data on the inhibitory effect on cytochrome P450 (CYP) 2D6 and a multi‐elimination pathway mediated by CYP3A4, uridine 5′‐diphosphate‐glucuronosyltransferase (UGT) 2B7 and butyrylcholinesterase (BChE). The aim of this study was to use this PBPK model to assess the magnitude of drug–drug interactions (DDIs) in an elderly population with severe renal impairment (sRI), which has not been evaluated in clinical trials. We first determined the system parameters, and meta‐analyses of literature data suggested that the abundance of UGT2B7 and the BChE activity in an elderly population with sRI was almost equivalent to and 20% lower than that in healthy young subjects, respectively. Other parameters, such as the CYP3A4 abundance, for an sRI population were used according to those built into the Simcyp Simulator. Second, we confirmed that the PBPK model reproduced the plasma concentration–time profile for mirabegron in an sRI population (simulated area under the plasma concentration–time curve (AUC) was within 1.5‐times that of the observed value). Finally, we applied the PBPK model to simulate DDIs in an sRI population. The PBPK model predicted that the AUC for mirabegron with itraconazole (a CYP3A4 inhibitor) was 4.12‐times that in healthy elderly subjects administered mirabegron alone, and predicted that the proportional change in AUC for desipramine (a CYP2D6 substrate) with mirabegron was greater than that in healthy subjects. In conclusion, the PBPK model was verified for the purpose of DDI assessment in an elderly population with sRI.     

Elevated Fibroblast Growth Factor 23 Exerts Its Effects on Placenta and Regulates Vitamin D Metabolism in Pregnancy of Hyp Mice

Fibroblast growth factor 23 (FGF23) functions in an endocrine fashion and requires α‐Klotho to exert its effects on the target organs. We have recently demonstrated that the human placenta also expresses α‐Klotho, which led us to hypothesize that FGF23 may exert effects on the placenta. Immunohistochemical analysis demonstrated the expression of FGF receptor 1 (FGFR1) as well as that of α‐Klotho in the feto‐maternal interface of both mouse and human normal‐term placentas, which suggested that these areas might be receptive to FGF23. Therefore, we next investigated whether FGF23 has some roles in the placenta using Hyp mice with high levels of circulating FGF23. Hyp and wild‐type (WT) females were mated with WT males, and the mothers and their male fetuses were analyzed. FGF23 levels in Hyp mothers were elevated. FGF23 levels were about 20‐fold higher in Hyp fetuses than in Hyp mothers, whereas WT fetuses from Hyp mothers exhibited low levels of FGF23, as did fetuses from WT mothers. We analyzed the placental gene expression and found that the expression of Cyp24a1 encoding 25OHD‐24‐hydroxylase, a target gene for FGF23 in the kidney, was increased in the placentas of fetuses from Hyp mothers compared with fetuses from WT mothers. In an organ culture of WT placentas, treatment with plasma from Hyp mothers markedly increased the expression of Cyp24a1, which was abolished by the simultaneous addition of anti‐FGF23 neutralizing antibody. The direct injection of recombinant FGF23 into WT placentas induced the expression of Cyp24a1. The increase in the placental expression of Cyp24a1 in fetuses from Hyp mothers resulted in decreased plasma 25‐hydroxyvitamin D levels. These results suggest that increased levels of circulating FGF23 in pathological conditions such as Hyp mice exerts direct effects on the placenta and affects fetal vitamin D metabolism via the regulation of Cyp24a1 expression. © 2014 American Society for Bone and Mineral Research.