Enhancement of Sphingomyelinase-Induced Endothelial Nitric Oxide Synthase-Mediated Vasorelaxation in a Murine Model of Type 2 Diabetes

Sphingolipids are important biological mediators both in health and disease. We investigated the vascular effects of enhanced sphingomyelinase (SMase) activity in a mouse model of type 2 diabetes mellitus (T2DM) to gain an understanding of the signaling pathways involved. Myography was used to measure changes in the tone of the thoracic aorta after administration of 0.2 U/mL neutral SMase in the presence or absence of the thromboxane prostanoid (TP) receptor antagonist SQ 29,548 and the nitric oxide synthase (NOS) inhibitor L-NAME. In precontracted aortic segments of non-diabetic mice, SMase induced transient contraction and subsequent weak relaxation, whereas vessels of diabetic (Lepr^db/Lepr^db, referred to as db/db) mice showed marked relaxation. In the presence of the TP receptor antagonist, SMase induced enhanced relaxation in both groups, which was 3-fold stronger in the vessels of db/db mice as compared to controls and could not be abolished by ceramidase or sphingosine-kinase inhibitors. Co-administration of the NOS inhibitor L-NAME abolished vasorelaxation in both groups. Our results indicate dual vasoactive effects of SMase: TP-mediated vasoconstriction and NO-mediated vasorelaxation. Surprisingly, in spite of the general endothelial dysfunction in T2DM, the endothelial NOS-mediated vasorelaxant effect of SMase was markedly enhanced.

Oncological Screening of Kidney Transplant Patients: The Role of Ultrasound Examination

INTRODUCTION

Immunosuppressive therapy used after organ transplantation represents a considerable oncological risk. Abdominal ultrasound examinations play an essential role in the oncological screening of organ transplant patients. Our aim was to study the effectiveness of the ultrasound screening protocol currently used in our clinic.

METHODS

Reports of screening abdominal ultrasound examinations of kidney transplant recipients were processed at the Department of Transplantation and Surgery of Semmelweis University from January 2012 to December 2015.

RESULTS

In 1478 studies, 14 patients were diagnosed with a malignant tumor, 11 of which were formed in the native shrunken kidney. The mean age for tumor diagnosis was 55.6 ± 12.6 years, and 80% of the patients diagnosed with tumor were male. On average, 7.5 ± 4.6 years passed between the transplantation and recognition of the tumor. All of the kidney tumors were diagnosed at an early stage: histologic examination of removed kidneys showed 73% pT1a- and 17% pT1b-stage tumors.

CONCLUSION

In our study, early stage shrunken kidney cancers were outstandingly the most common post-transplant malignancies found by ultrasound screening. Annual ultrasound examinations as part of our current screening protocol allowed the detection of tumors at an early stage in kidney transplant recipients.

Diagnosis and Management of a De Novo Urothelial Carcinoma in a Kidney Allograft: A Case Report

INTRODUCTION

Following renal transplantation, the incidence of malignancies is 3-5 times higher than that of healthy individuals. Among other type of cancers, the risk of urological tumors is also elevated. However, only a few cases of de novo transitional cell carcinomas occurring in renal allografts have been reported.

CASE REPORT

A 63-year-old tertiary transplanted male patient was urgently hospitalized for a painless macroscopic hematuria. Ultrasonography revealed pyelectasis and a hematoma in the renal pelvis. A percutaneous nephrostomy tube was inserted. An anterograde pyelography was performed later, where a filling defect was still observable in the location of the previously reported hypoechoic mass. Contrast-enhanced ultrasonography showed enhancement of the lesion. An ultrasound-guided percutaneous biopsy was performed. The histologic evaluation revealed a high-grade transitional cell carcinoma. A whole-body staging computed tomography scan did not show signs of metastatic disease. The renal allograft was surgically removed. No disease progression was observed during the 21-month follow-up period.

CONCLUSIONS

Painless hematuria and asymptomatic hydronephrosis occurring after kidney transplantation should raise the possibility of urothelial carcinoma in the kidney graft. Contrast-enhanced ultrasound should be considered as a first-line diagnostic modality because it is easily accessible and does not raise concerns about nephrotoxicity or radiation burden.

Management of Portal Hypertension After Liver Transplantation

INTRODUCTION

Post-transplantation portal hypertension has severe complications, such as esophageal varix bleeding, therapy refractory ascites, extreme splenomegaly, and graft dysfunction. The aim of our study was to analyze the effectiveness of the therapeutic strategies and how to visualize the procedure.

METHODS

A retrospective study involving liver transplantation patients from the Semmelweis University Department of Transplantation and Surgery was performed between 2005 and 2015. The prevalence, etiology, and leading complications of the condition were determined. The applied interventions' effects on the patients' ascites volume, splenic volume, and the occurrence of variceal bleeding were determined. Mean portal blood flow velocity and congestion index values were calculated using Doppler ultrasonography.

RESULTS

The prevalence of post-transplantation portal hypertension requiring intervention was 2.8%. The most common etiology of the disease was portal anastomotic stenosis. The most common complications were esophageal varix bleeding and therapy refractory ascites. The patients' ascites volume decreased significantly (2923.3 ± 1893.2 mL vs. 423.3 ± 634.3 mL; P < .05), their splenic volume decreased markedly. After the interventions, only one case of recurrent variceal bleeding was reported. The calculated Doppler parameters were altered in the opposite direction in cases of pre-hepatic versus intra- or post-hepatic portal hypertension. After the interventions, these parameters shifted towards the physiologic ranges.

CONCLUSION

The interventions performed in our clinic were effective in most cases. The patients' ascites volume, splenic volume, and the prevalence of variceal bleeding decreased after the treatment. Doppler ultrasonography has proved to be a valuable imaging modality in the diagnosis and the follow-up of post-transplantation portal hypertension.