Enhanced desalination performance in compacted carbon-based reverse osmosis membranes.

Reverse osmosis membranes typically suffer compaction during the initial stabilization stage due to the applied hydraulic pressure, altering the desalination performance. The elucidation of the underlying transformations during compaction is key for further development of new membranes and its deployment in real-world scenarios. Hydraulic compaction of amorphous carbon (a-C) based membranes under cross-flow operation for water purification and desalination has been observed experimentally, and analysed employing molecular dynamics simulations. The previous outstanding separation performance for carbon membranes, especially for the nitrogen-containing (a-C:N) type, has been studied during compaction using lab-scale cross-flow desalination membrane systems. Our results indicate that the high-water pressure induces an overall reduction in the interstitial spaces within the a-C structure. Remarkably, the compacted a-C:N membrane exhibits improved performance in salt rejection and water permeability, compared to the a-C based membrane. Our analysis shows that performance improvement can be related to the higher mechanical stability of the carbon structure due to the presence of nitrogen sites, which also promote water diffusion and permeability. These results show that a-C:N based membranes are a feasible alternative to conventional polymeric membranes.

[A case of type 2 diabetes mellitus complicated with left iliopsoas abscess caused by a left femoral vein catheter during treatment for right pyothorax and right subphrenic abscess].

A 78-year-old man was receiving regular treatment for diabetes and dementia at our hospital. Diabetes was diagnosed about 10 years previously, at which time the patient's HbA(1)c level had been maintained at 6% by diet therapy and an oral hypoglycemic agent. In July, 2008, he was admitted with fever and hospitalized for pneumonia, which improved with antibiotic treatment and chest drainage. However, pyothorax developed, and in October, 2008 he was admitted again with fever and inflammation. A chest computed tomography (CT) scan revealed a right subphrenic abscess, which improved with antibiotic treatment. He was readmitted for fever and lumbago in November, 2008, and an abdominal CT scan showed a left iliopsoas abscess that did not improve with antibiotic treatment, and had increased in size. Due to infection from the central vein catheter in the left femoral vein inserted at the end of October, the catheter was withdrawn at the end of November. There was a rapid reduction of the left iliopsoas abscess, his inflammation and lumbago symptoms reduced, and he was discharged in January 2009. In cases of dementia in elderly with diabetes, a catheter from a femoral vein is frequently used to prevent complications. However, this method has been known to result in infection at the site of the catheter, and to cause fever. The circumstances of this case strongly support the removal of such a catheter in elderly patients at the first indication of persistent infection.

Coronary artery calcification, arterial stiffness and renal insufficiency associate with serum levels of tumor necrosis factor-alpha in Japanese type 2 diabetic patients.

Although the kidneys are the major source of proinflammatory cytokines, association of tumor necrosis factor-alpha (TNF-alpha) with severity of atherosclerosis or kidney function in diabetic patients is unclear. Two hundred type 2 diabetic patients and 30 age-matched nondiabetic subjects consecutively admitted to our hospital were enrolled. The Agatston coronary artery calcium score (CACS), a quantitative marker of coronary atherosclerosis, was obtained using multidetector-row computed tomography. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV). Diabetic patients had higher log(CACS+1) (p=0.0089), baPWV (p=0.0293), frequency of elevated urinary albumin excretion (UAE) (p<0.0001) and TNF-alpha (p=0.0029) and similar estimated glomerular filtration rate (eGFR) compared to nondiabetic subjects. When diabetic patients were grouped into four subgroups with or without elevated UAE and renal insufficiency (UAE of >/=30 or <30mg/24h and eGFR of <60 or >/=60ml/min per 1.73m(2)), patients with micro- and macroalbuminuric renal insufficiency showed the highest log(CACS+1) (p<0.0001), baPWV (p=0.0068) and TNF-alpha (p<0.0001) of these groups. Log(CACS+1) (p=0.0008) and baPWV (p=0.0006) positively and eGFR (p<0.0001) negatively correlated with TNF-alpha in diabetic patients. We find that coronary artery calcification, arterial stiffness, and renal insufficiency associate with circulating levels of TNF-alpha in type 2 diabetic patients.

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.

Characteristics of myogenic tone in the rat ophthalmic artery.

The pressure-induced constriction in the rat ophthalmic artery was characterized. Ophthalmic arteries were isolated, cannulated in an arteriograph, and pressurized. Arteries developed 25% constriction at 70 mmHg of intraluminal pressure. Arteries maintained almost similar diameter over the range of pressures 50-210 mmHg, and forced dilatation was observed at pressures >210 mmHg. Denudation of endothelium increased the sensitivity of arteries to pressure-induced constriction, and significantly higher myogenic tone was observed in the pressure range of 10-100 mmHg. Indomethacin and cyclooxygenase-2 inhibition by SC-236 decreased myogenic tone, whereas cyclooxygenase-1 inhibition by SC-560 potentiated myogenic tone in a lower concentration range and decreased at a higher concentration. Pressure-induced constriction was completely blocked by 1 microM nifedipine. Phospholipase C inhibition by 6 microM U-73122 decreased myogenic tone by 39%, whereas PKC inhibitor GF-109203X (3 microM) had no effect. Constriction to phenylephrine was significantly decreased by U-73122 (1 microM) and GF-109203X (3 microM) at an intraluminal pressure of 10 mmHg. Rho-kinase inhibition by Y-27632 (30 microM) and HA-1077 (30 microM) decreased myogenic tone by 75% and 73%, respectively, and 1 microM Y-27632 significantly decreased myogenic tone developed in response to graded increases in pressure. These results suggest that rat ophthalmic artery has an efficient pressure-dependent autoregulatory function that is modulated by endothelium. Contribution of phospholipase C-activation to myogenic tone is minimal, whereas Rho-kinase activation plays a predominant role in the myogenic reactivity in this artery.

Myogenic tone and reactivity of rat ophthalmic artery in acute exposure to high glucose and in a type II diabetic model.

PURPOSE: To evaluate the effect of acute exposure to high glucose on myogenic tone and reactivity of the rat ophthalmic artery and to compare the observations with that in ophthalmic artery from a diabetic rat model. METHODS: Ophthalmic arteries from Sprague-Dawley rats were pressurized at 70 mmHg in an arteriograph, and outer diameter was monitored. Myogenic tone was assessed over a range of intraluminal pressures in the presence and absence of high glucose or mannitol. The effects of high glucose on reactivity to carbachol and phenylephrine were determined. Arteries from type II diabetic BBZDR/Wor rats and age-matched control rats were evaluated for myogenic tone and reactivity. RESULTS: Myogenic tone was enhanced by 25 mM, but decreased by 40 mM, glucose and was not affected by mannitol. Constriction to phenylephrine was not affected by 25 mM, but was decreased by 40 mM glucose, and carbachol-mediated dilation was unaffected. Effects of high glucose were not observed in the absence of endothelium. Miconazole, a nonselective inhibitor of cytochrome-P450 enzymes or dihydro-ouabain, an inhibitor of Na+,K+-ATPase blocked the effect of 40 mM but not 25 mM glucose. Arteries from diabetic rats showed decreased myogenic tone compared with control arteries, and this decrease was not observed in the absence of endothelium. CONCLUSIONS: Acute exposure to high glucose has a concentration- and endothelium-dependent effect on the myogenic tone of rat ophthalmic artery. Attenuation of tone by high glucose is probably due to the activation of smooth muscle Na+,K+-ATPase by endothelial cytochrome-P450 metabolite. Pressure-mediated autoregulation in ophthalmic artery in type II diabetic BBZDR/Wor rat operates at lower resistance, probably due to hyperglycemia.