Cooperative action of APJ and α1A-adrenergic receptor in vascular smooth muscle cells induces vasoconstriction.

The apelin receptor (APJ), a receptor for apelin and elabela/apela, induces vasodilation and vasoconstriction in blood vessels. However, the prolonged effects of increased APJ-mediated signalling, involving vasoconstriction, in smooth muscle cells have not been fully characterized. Here, we investigated the vasoactive effects of APJ gain of function under the control of the smooth muscle actin (SMA) gene promoter in mice. Transgenic overexpression of APJ (SMA-APJ) conferred sensitivity to blood pressure and vascular contraction induced by apelin administration in vivo. Interestingly, ex vivo experiments showed that apelin markedly increased the vasoconstriction of isolated aorta induced by noradrenaline (NA), an agonist for α- and ß-adrenergic receptors, or phenylephrine, a specific agonist for α1-adrenergic receptor (α1-AR). In addition, intracellular calcium influx was augmented by apelin with NA in HEK293T cells expressing APJ and α1A-AR. To examine the cooperative action of APJ and α1A-AR in the regulation of vasoconstriction, we developed α1A-AR deficient mice using a genome-editing technique, and then established SMA-APJ/α1A-AR-KO mice. In the latter mouse line, aortic vasoconstriction induced by a specific agonist for α1A-AR, A-61603, were significantly less than in SMA-APJ mice. These results suggest that the APJ-enhanced response requires α1A-AR to contract vessels coordinately.

More stable and reliable pharmacokinetics with preprandial administration of cyclosporine compared with postprandial administration in patients with refractory nephrotic syndrome.

STUDY OBJECTIVE: To compare the absorption profile of cyclosporine after preprandial administration with that after postprandial administration, and to determine which administration time resulted in a more stable absorption profile and the timing of the drug concentration that was the most reliable marker for monitoring drug absorption. DESIGN: Prospective analysis. SETTING: University teaching hospital in Japan. PATIENTS: Sixteen patients with refractory nephrotic syndrome. INTERVENTION: Thirteen patients received cyclosporine after breakfast (postprandial group) and eight received the drug 30 minutes before breakfast (preprandial group). MEASUREMENTS AND MAIN RESULTS: Blood cyclosporine concentration was measured 5 times serially: before administration (C 0 ) and at 1-hour intervals until 4 hours after administration of cyclosporine (C 1 -C 4 ). Also, area under the concentration-time curve from 0-4 hours (AUC 0-4 ) was calculated. Of the 13 patients in the postprandial group, six (46%) showed fair absorption and exhibited a peak concentration at C 1 or C 2 (high-absorption pattern); seven (54%) showed poor absorption and did not reach the peak concentration within the 4-hour period (low-absorption pattern). Five of the seven patients with the low-absorption pattern were switched from postprandial to preprandial administration. All patients in the preprandial administration group showed a high-absorption pattern and reached the peak cyclosporine concentration at C 1 . The C 2 value showed the best correlation with AUC 0-4 in both groups, and the C 0 parameter did not correlate with AUC 0-4 in either group. CONCLUSION: Preprandial administration provided a more stable absorption profile of cyclosporine compared with postprandial administration. From the correlation with AUC 0-4 , we concluded that C 2 , and not C 0 , is a reliable marker for monitoring cyclosporine exposure.

Hypertension accelerates diabetic nephropathy in Wistar fatty rats, a model of type 2 diabetes mellitus, via mitogen-activated protein kinase cascades and transforming growth factor-beta1.

Although it is known that diabetic nephropathy is accelerated by hypertension, the mechanisms involved in this process are not clear. In this study we aimed to clarify these mechanisms using male Wistar fatty rats (WFR) as a type 2 diabetic model and male Wistar lean rats (WLR) as a control. Each group was fed a normal or high sodium diet from the age of 6 to 14 weeks. We determined the blood pressure and urinary albumin excretion (UAE). At the end of the study, the expressions of mitogen-activated protein kinases (MAPK) and transforming growth factor-beta1 (TGF-beta1) were examined in the isolated glomeruli by Western blot analysis, and the number of glomerular lesions was determined by conventional histology. High sodium load caused hypertension and a marked increase in UAE in the WFR but not in the WLR. Glomerular volume was increased in the hypertensive WFR. There was no difference among the four groups in the expression of c-Jun-NH2-terminal kinase (JNK). In contrast, the expressions of extracellular signal-regulated kinase 1/2 (ERK1/2) and its upstream regulator, MAPK/ERK kinase 1 (MEK1), were augmented in the hypertensive WFR. Expression of p38 MAPK was increased in the normotensive WFR, and further enhanced in the hypertensive WFR. Moreover, administration of high sodium load to WFR augmented the expression of TGF-beta1. In conclusion, systemic hypertension in WFR accelerates the diabetic nephropathy in type 2 diabetes via MEK-ERK and p38 MAPK cascades. TGF-beta1 is also involved in this mechanism.

[Takotsubo cardiomyopathy thought to be induced by MRSA meningitis and cervical epidural abscess in a maintenance-hemodialysis patient: case report].

A 65-year-old man was admitted to our hospital for high fever and severe left shoulder pain. He was initiated on maintenance hemodialysis for end-stage renal failure caused by diabetic nephropathy 9 years previously. On admission, the serum CRP level was 29.3 mg/d/l and the white blood cell count was 29,000/mm3. Bacterial examination of blood and spinal fluid revealed MRSA colonization. On the 6th hospital day, a giant negative T wave in the V2-6 leads of an electrocardiogram asymptomatically appeared. Ultracardiogram revealed apical systolic paradoxical centrifugal motion. None of the cardiogenic enzymes, such as creatine kinase, lactate dehydrogenase and glutamic oxaloacetic transaminase was elevated. Cardiac thallium-201-chloride (201Tl-Cl) and I-123 beta-metyl iodophenyl-pentadecanoic acid (123I-BMIPP) scintigraphy revealed a decreased accumulation of isotopes in the apex. From these findings, we diagnosed Takotsubo cardiomyopathy induced by MRSA meningitis. Vancomycin was administrated and the inflammatory signs decreased. On the 46th hospital day, tetraplegia and respiratory suppression occurred. A cervical spinal magnetic resonance image revealed cervical spondylodiscitis and cervical epidural abscess, which compressed the medulla oblongata. Surgical spinal decompression and drainage of the abscess were performed. The giant negative T wave in the electrocardiogram improved after the operation. Two months after the operation, cardiac 201Tl-Cl scintigraphy revealed improvement in the accumulation of isotopes in the apex. Takotsubo cardiomyopathy is secondary cardiomyopathy presenting with apical systolic paradoxical centrifugal motion without coronary stenotic disease. It has been reported to be induced by severe mental stress or intracranial disease. In the present patient, it was predicted that stress on the central nerve system caused by the MRSA meningitis and the cervical epidural abscess induced the Takotsubo cardiomyopathy.

Membranous nephropathy associated with chronic hepatitis B occurring in a short period after acute hepatitis B virus infection.

We herein present a case of membranous nephropathy associated with chronic hepatitis B following acute hepatitis B virus (HBV) infection. A 22-year-old man was admitted to our hospital for evaluation of proteinuria, pitting edema on both legs, and increased body weight in December 2002. At the age of 18, he had suffered from acute hepatitis A and syphilis, and was found to be negative for hepatitis B surface antigen (HBsAg). Furthermore, he suffered from acute hepatitis B (AH-B) at the age of 21; he was found to be positive for HBsAg and anti-IgM antibody to core antigen (IgM HBcAb). However, he discontinued outpatient treatment before confirmation of HBsAg clearance or the appearance of antibody to HBsAg (HBsAb). At the present admission, HBsAg, antibody to hepatitis B e antigen (HBeAg), and HBcAb were positive, while IgM HBcAb was negative. His genotype of HBV was type A (HBV/A). Histopathological findings of the renal biopsy specimen confirmed glomerulonephritis and glomerular deposition of HBsAg. Thus, he was diagnosed as having nephrotic syndrome caused by membranous nephropathy (MN) associated with chronic hepatitis B (CH-B) following AH-B. Although interferon-alpha (IFN-alpha) administration was started for the treatment and temporary improvement of proteinuria was observed, remission of MN was not achieved.