Inhibitory effects of indoxyl sulfate and creatinine on the renal transport of meropenem and biapenem in rats.

Carbapenem antibiotics are excreted preferentially in the urine after intravenous administration, with organic anion transporters (OATs) known to be involved in the renal tubular secretion of carbapenem antibiotics. Various uremic toxins (UTs) accumulate in the blood of patients with end-stage renal failure, and some UTs such as indoxyl sulfate (IS) and creatinine (Cr) are excreted in the urine via OATs. However, information about the possible interactions between these UTs and carbapenems in the renal secretion remains limited. In this study, we investigated the effects of IS and Cr on the renal transport of anionic meropenem and zwitterionic biapenem by using rat renal cortical slices. The uptake of meropenem and biapenem in the renal cortical slices was significantly decreased in the presence of 0.1 mM IS or 1 mM Cr. When biapenem and Cr were co-administered to rats intravenously, biapenem clearance from the plasma was clearly retarded, reflecting the current in vitro results. However, IS and Cr exerted no inhibitory effect on the uptake of metformin, a substrate of renal organic cation transporter (OCT) 2, in the renal cortical slices. Thus, our findings indicate that IS and Cr interfere with the renal secretion of carbapenem antibiotics by preferentially inhibiting OATs.

[Dermatomyositis-Like Symptoms Useful for Diagnosis of Ureteral Cancer].

We here report a case of dermatomyositis associated with ureteral cancer. A 69-year-old male presented to our hospital complaining of a rash on his whole body, which resulted in a clinical diagnosis of dermatomyositis. Right ureteral cancer was suspected on computed tomographic CT examination during the investigation for the underlying malignancy. The patient was treated with prednisolone and right nephroureterectomy with bladder cuffing for dermatomyositis and ureteral cancer, respectively. One year after surgery, the dermatomyositis worsened, and CT examination showed local recurrence and lymph node metastasis. Chemotherapy was performed, and CT examination 3 months after treatment showed that the tumor had shrunk. Skin symptoms were also ameliorated. Chemotherapy was given intermittently thereafter. The tumor then increased and skin symptoms reappeared ; 3 years after surgery the patient's general condition deteriorated, resulting in death. Ureteral cancer with dermatomyositis is rare, but dermatomyositis complicated with malignancy has a poor prognosis. Careful whole body search may be useful for early detection of malignancy.

A Case of Urachal Carcinoma of the Abdominal Wall in a Kidney Transplant Recipient.

Urachal carcinoma is an extremely rare malignant tumor arising from the urachus in the fetus. We report a patient who developed urachal carcinoma 18 years after kidney transplantation. A 59-year-old man was admitted because of abdominal pain and massive ascites. He had undergone kidney transplantation 18 years earlier and had end-stage renal disease requiring dialysis. Abdominal CT showed massive ascites and an abdominal wall cystic mass separated from the peritoneal cavity. Hemodialysis was started, and paralytic ileus was diagnosed and treated. His ileus symptoms improved temporarily, but he died of myocardial infarction. An autopsy was performed, which revealed cystadenocarcinoma in the abdominal wall mass, leading to a diagnosis of urachal carcinoma.