[Intermittent opening of a mechanical mitral valve prosthesis due to pannus formation; report of a case]

A 76-year-old woman with a history of severe mitral valve stenosis had undergone mitral valve replacement with a 27 mm St. Jude Medical (SJM) valve in 1991. Follow-up transthoracic echocardiography revealed an increase in the pressure gradient across the mitral prosthesis 16 years after the surgery. Prosthetic valve dysfunction was suspected, but transesophageal echocardiography and cineradiography failed to show mechanical valve dysfunction. Two years later, she presented with dyspnea on exertion and leg edema. Cineradiography revealed intermittent restriction of the opening of the mechanical valve leaflet approximately every 10 beats. Thus, we diagnosed intermittent prosthetic valve dysfunction and performed a reoperation. On inspection of the prosthesis, we observed semicircular pannus formation around the posterior leaflet in the ventricular side. It was considered that the pannus tissue had interfered with 1 leaflet opening of the mitral valve prosthesis, resulting in intermittent valve dysfunction. We replaced the prosthesis with a new 25 mm SJM valve. The patient was discharged after confirmation of normal prosthetic function.

Renoprotective effects of asialoerythropoietin in diabetic mice against ischaemia-reperfusion-induced acute kidney injury

AIM

Diabetic patients are at higher risk of failure to recover after acute kidney injury, however, the mechanism and therapeutic strategies remain unclear. Erythropoietin is cytoprotective in a variety of non-haematopoietic cells. The aim of the present study was to clarify the mechanism of diabetes-related acceleration of renal damage after ischaemia-reperfusion injury and to examine the therapeutic potential of asialoerythropoietin, a non-haematopoietic erythropoietin derivative, against ischaemia-reperfusion-induced acute kidney injury in diabetic mice.

METHODS

C57BL/6J mice with and without streptozotocin-induced diabetes were subjected to 30 min unilateral renal ischaemia-reperfusion injury at 1 week after induction of diabetes. They were divided into four group: (i) non-diabetic plus ischaemia-reperfusion injury; (ii) non-diabetic plus ischaemia-reperfusion injury plus asialoerythropoietin (3000 IU/kg bodyweight); (iii) diabetic plus ischaemia-reperfusion injury; and (iv) diabetic plus ischemia-reperfusion injury plus asialoerythropoietin. Experiments were conducted at the indicated time periods after ischaemia-reperfusion injury.

RESULTS

Ischaemia-reperfusion injury of diabetic kidney resulted in significantly low protein expression levels of bcl-2, an anti-apoptotic molecule, and bone morphogenetic protein-7 (BMP-7), an anti-fibrotic and pro-regenerative factor, compared with non-diabetic kidneys. Diabetic kidney subsequently showed severe damage including increased tubular cell apoptosis, tubulointerstitial fibrosis and decreased tubular proliferation, compared with non-diabetic kidney. Treatment with asialoerythropoietin induced bcl-2 and BMP-7 expression in diabetic kidney and decreased tubular cell apoptosis, tubulointerstitial fibrosis and accelerated tubular proliferation.

CONCLUSION

Reduced induction bcl-2 and BMP-7 may play a role in the acceleration of renal damage after ischaemia-reperfusion injury in diabetic kidney. The renoprotective effects of asialoerythropoietin on acute kidney injury may be mediated through the induction of bcl-2 and BMP-7.

Induction of Th1 immune responses to Japanese cedar pollen allergen (Cry j 1) in mice immunized with Cry j 1 conjugated with CpG oligodeoxynucleotide

We determined whether a major Japanese cedar pollen allergen (Cry j 1) conjugated with CpG oligodeoxynucleotide would enhance allergen-specific Th1 responses in mice. Cry j 1 conjugated with CpG (Cry j 1-CpG) induced IL-12 in the spleen cells of naïve mice. Cry j 1-CpG immunization of BALB/c mice suppressed anti-Cry j 1 IgE response and enhanced anti-Cry j 1 IgG(2a) to subsequent Cry j 1 and alum adjuvant injection. CD4(+)T cells isolated from the spleens in mice immunized with Cry j 1-CpG produced higher IFN-γ levels than did CD4(+)T cells obtained from mice as negative controls. Our results suggested that Cry j 1-CpG immunization can induce Cry j 1-specific Th1 immune responses, thereby inhibiting IgE response to the pollen allergen.

Serum inflammatory proteins and frontal lobe dysfunction in patients with cardiovascular risk factors

BACKGROUND

Recent studies have shown that the levels of circulating inflammatory markers are associated with cognitive decline and cerebral small-vessel disease. Frontal lobe dysfunction is believed to be a relatively characteristic neuropsychological symptom in vascular cognitive impairment caused by cerebral small-vessel disease. The purpose of this study was to investigate whether the levels of serum inflammatory markers are associated with frontal lobe dysfunction, particularly executive dysfunction.

METHODS

Between January 2003 and September 2007, 388 patients who had one or more atherosclerotic risk factors and subsequently underwent brain MRI and neuropsychological testing including mini-mental state examination (MMSE), frontal assessment battery (FAB), and modified Stroop test were enrolled in this study. We evaluated the effect of serum levels of inflammatory markers and white matter lesions on frontal lobe function.

RESULTS

The FAB score was negatively correlated with serum inflammatory marker levels (hsCRP; r = -0.170, IL-6; r = -0.143, IL-18; r = -0.175) and white matter lesions. In the modified Stroop test, interference measure was positively correlated with the levels of hsCRP (r = -0.198), and IL-18 (r = -0.152), and white matter lesions. However, the MMSE score was not correlated with either inflammatory marker levels. The association between hsCRP and FAB score or interference measure remained significant when controlling for other confounding factors and MRI findings.

CONCLUSIONS

The circulating level of hsCRP is associated with frontal lobe dysfunction in patients with cardiovascular risk factors independent of white matter lesions in brain MRI.

Measurement of activities in two different angiotensin II generating systems, chymase and angiotensin-converting enzyme, in the vitreous fluid of vitreoretinal diseases: A possible involvement of chymase in the pathogenesis of macular hole patients

PURPOSE

To investigate possible involvement of chymase and angiotensin-converting enzyme (ACE) in the pathogenesis of vitreoretinal diseases, both of which are related to the production of angiotensin II.

METHODS

We measured chymase and ACE activities in the vitreous in the 54 affected eyes of 54 patients who had undergone vitreous surgery for idiopathic macular holes (MH, n = 14), proliferative diabetic retinopathy (PDR, n = 14), idiopathic epiretinal membranes (ERM, n = 13), and rhegmatogenous retinal detachment (RRD, n = 13).

RESULTS

Chymase activities in the vitreous from patients with MH, PDR, ERM, and RRD were 1.87 +/- 0.53, 0.06 +/- 0.04, 0.40 +/- 0.12, and 0.08 +/- 0.03 (mean +/- SE) mU/mg protein, respectively, and ACE activities in the vitreous humor were 0.18 +/- 0.09, 0.30 +/- 0.07, 0.01 +/- 0.01, and 0.03 +/- 0.02 (mean +/- SE) mU/mg protein, respectively. Chymase activity was significantly elevated in MH among these diseases (p < 0.01, Scheffe), and ACE was significantly activated in PDR compared to ERM and RRD (p < 0.05, Scheffe).

CONCLUSIONS

Our results suggest that two different angiotensin II generating systems are activated in human vitreous humor; an increased activity of chymase may play a possible role in the formation of macular holes.

Higher arterial stiffness, greater peripheral vascular resistance and lower blood flow in lower-leg arteries are associated with long-term hyperglycaemia in type 2 diabetic patients with normal ankle-brachial index

BACKGROUND

Higher arterial stiffness and greater peripheral vascular resistance reduce blood flow in lower-leg arteries and contribute to the development of ischaemic limb in diabetic patients even without peripheral artery occlusive disease. The aim of this study was to clarify whether these vascular parameters are associated with long-term hyperglycaemia in diabetic patients.

METHODS

We examined 45 type 2 diabetic patients and 38 age-matched nondiabetic subjects without peripheral artery occlusive disease assessed by ankle-brachial index consecutively admitted to our hospital, and followed them over a 3-year period (3.7 +/- 0.7 years) with no vasodilative medication. Blood flow and resistive index, a measure of peripheral vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial-ankle pulse wave velocity was measured to assess arterial stiffness.

RESULTS

At baseline, consistent with our previous report, diabetic patients showed higher brachial-ankle pulse wave velocity (p < 0.0001) and resistive index (p < 0.0001) and lower flow volume (p = 0.0044) than those of nondiabetic subjects. Stepwise multiple regression analysis revealed that duration of diabetes, mean HbA(1c) during the study, use of renin-angiotensin system inhibitors and change per year in resistive index were identified as significant independent variables predicting change per year in blood flow (r(2) = 0.733, p < 0.0001) in diabetic patients. Mean HbA(1c) during the study was positively correlated with changes per year in brachial-ankle pulse wave velocity (p = 0.00007) and resistive index (p = 0.0014) and was negatively correlated with that in blood flow (p < 0.0001) in diabetic patients.

CONCLUSIONS

Long-term hyperglycaemia is a major cause of impaired peripheral circulation in lower-leg arteries in diabetic patients without peripheral artery occlusive disease.

Exendin-4 has an anti-hypertensive effect in salt-sensitive mice model

The improvement of salt-sensitive hypertension is a therapeutic target for various vascular diseases. Glucagon-like peptide 1 (GLP-1), an incretin peptide, has been reported to have natriuretic effect as well as blood glucose lowering effect, although its exact mechanism and clinical usefulness remain unclear. Here, we examined anti-hypertensive effect of exendin-4, a GLP-1 analog, in salt-sensitive obese db/db mice and angiotensin II (angII)-infused C57BLK6/J mice. The treatment of exendin-4 for 12 weeks inhibited the development of hypertension in db/db mice. In db/db mice, the urinary sodium excretion was delayed and blood pressure was elevated in response to a high-salt load, whereas these were attenuated by exendin-4. In db/db mice, intra-renal angII concentration was increased. Furthermore, exendin-4 prevented angII-induced hypertension in non-diabetic mice and inhibited angII-induced phosphorylation of ERK1/2 in cultured renal cells. Considered together, our results indicate that exendin-4 has anti-hypertensive effects through the attenuation of angII-induced high-salt sensitivity.

Structural and functional changes in the kidneys of high-fat diet-induced obese mice

Metabolic syndrome has been reported to be associated with chronic kidney disease, but the mechanisms remain unclear. Although feeding of a high-fat diet (HFD) to C57BL/6 mice is reported to induce systemic metabolic abnormalities and subsequent renal injuries, such as albuminuria, similar to human metabolic syndrome, alterations in HFD-induced renal injuries have not been fully elucidated in detail. We therefore investigated the structural and functional changes in the kidneys of C57BL/6 mice on a HFD. Six-week-old mice were fed a low-fat diet (LFD; 10% of total calories from fat) or a HFD (60% fat) for 12 wk. Mice fed a HFD showed significant increases in body weight, systolic blood pressure, plasma insulin, glucose, and triglycerides compared with those on a LFD. Accompanying these systemic changes, mice on a HFD showed albuminuria, an increase in glomerular tuft area, and mesangial expansion. These systemic and renal alterations in mice on a HFD were prevented by body weight control with the dietary restriction of feeding a HFD. Furthermore, mice on a HFD showed renal pathophysiological alterations including renal lipid accumulation, an increased accumulation of type IV collagen in glomeruli, an increase in macrophage infiltration in the renal medulla, an increase in urinary 8-hydroxy-2'-deoxyguanosine excretion, and impaired sodium handling. In conclusion, this study suggests that local metabolic alterations in the kidney play important roles in the development of renal injury associated with metabolic syndrome in addition to systemic metabolic changes and an increase in body weight.

Cytopathic avian rotavirus isolated from duck faeces in chicken kidney cell cultures

Five cytopathic viruses morphologically resembling rotaviruses were isolated from duck faeces in chicken kidney cell cultures using conventional methods. One of the isolates, designated F-29 strain, was identified as an avian rotavirus from the following: ribonucleic acid in the viral core, virus growth in the cytoplasm, resistance to chloroform, acid and heating, partial stabilisation to molar magnesium chloride and rotavirus-like morphology by electron microscopy. By immunofluorescence, F-29 strain did not react with porcine and bovine rotaviruses. Neutralising antibodies to the F-29 strain were detected in sera collected from a conventional duck flock, but not from specific-pathogen-free duck flocks.

REIC/Dkk-3 overexpression downregulates P-glycoprotein in multidrug-resistant MCF7/ADR cells and induces apoptosis in breast cancer

The overexpression of reduced expression in immortalized cells (REIC)/Dickkopf-3 (Dkk-3), a tumor suppressor gene, induced apoptosis in human prostatic and testicular cancer cells. The aim of this study is to examine the potential of REIC/Dkk-3 as a therapeutic target against breast cancer. First, the in vitro apoptotic effect of Ad-REIC treatment was investigated in breast cancer cell lines and the adenovirus-mediated overexpression of REIC/Dkk-3 was thus found to lead to apoptotic cell death in a c-Jun-NH(2)-kinase (JNK) phosphorylaion-dependent manner. Moreover, an in vivo apoptotic effect and MCF/Wt tumor growth inhibition were observed in the mouse model after intratumoral Ad-REIC injection. As multidrug resistance (MDR) is a major problem in the chemotherapy of progressive breast cancer, the in vitro effects of Ad-REIC treatment were investigated in terms of the sensitivity of multidrug-resistant MCF7/ADR cells to doxorubicin and of the P-glycoprotein expression. Ad-REIC treatment in MCF7/ADR cells also downregulated P-glycoprotein expresssion through JNK activation, and sensitized its drug resistance against doxorubicin. Therefore, not only apoptosis induction but also the reversal of anticancer drug resistance was achieved using Ad-REIC. We suggest that REIC/Dkk-3 is a novel target for breast cancer treatment and that Ad-REIC might be an attractive agent against drug-resistant cancer in combination with conventional antineoplastic agents.

Impaired peripheral circulation in lower-leg arteries caused by higher arterial stiffness and greater vascular resistance associates with nephropathy in type 2 diabetic patients with normal ankle-brachial indices

Diabetic nephropathy is a major cause of lower-limb amputation. We enrolled 250 type 2 diabetic patients without apparent occlusive peripheral arterial disease (ankle-brachial indices >0.9) and 40 age-matched nondiabetic subjects consecutively admitted to our hospital. Flow volume and resistive index (RI), an index of vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of arterial distensibility. Flow volume was negatively correlated with both baPWV (p=0.0009) and RI (p<0.0001) among the patients. When the patients were grouped into four subgroups with or without albuminuria and renal insufficiency according to the levels of urinary albumin excretion rate (>or=20 or <20microg/min) and estimated glomerular filtration rate (eGFR) (<60 or >or=60ml/min/1.73m(2)), albuminuric patients with renal insufficiency (n=30) showed the lowest flow volume (p=0.0078) and the highest baPWV (p=0.0006) and RI (p=0.0274) among the groups. Simple linear regression analyses demonstrated that eGFR correlated positively with flow volume (p=0.0020) and negatively with baPWV (p=0.0258) and RI (p=0.0029) in patients with albuminuria (n=92), but not with normoalbuminuria (n=158). Impaired peripheral circulation in lower-leg arteries associates with nephropathy in diabetic patients even though they have normal ankle-brachial indices.

Asialoerythropoietin prevents contrast-induced nephropathy

Strategies to prevent contrast-induced nephropathy (CIN) are suboptimal. Erythropoietin was recently found to be cytoprotective in a variety of nonhematopoietic cells, so it was hypothesized that the nonhematopoietic erythropoietin derivative asialoerythropoietin would prevent CIN. Nephropathy was induced in rats by injection of the radiocontrast medium Ioversol in addition to inhibition of prostaglandin and nitric oxide synthesis. Administration of a single dose of asialoerythropoietin before the induction of nephropathy significantly attenuated the resulting renal dysfunction and histologic renal tubular injury. Contrast-induced apoptosis of renal tubular cells was inhibited by asialoerythropoietin both in vivo and in vitro, and this effect was blocked by a Janus kinase 2 (JAK2) inhibitor in vitro. Furthermore, phospho-JAK2/signal transducer and activator of transcription 5 (STAT5) and heat-shock protein 70 increased after injection of asialoerythropoietin, suggesting that the effects of asialoerythropoietin may be mediated by the activation of the JAK2/STAT5 pathway. Overall, these findings suggest that asialoerythropoietin may have potential as a new therapeutic approach to prevent CIN given its ability to preserve renal function and directly protect renal tissue.