Drawing and Hydrophobicity-patterning Long Polydimethylsiloxane Silicone Filaments.

Polydimethylsiloxane (PDMS) silicone is a versatile polymer that cannot readily be formed into long filaments. Traditional spinning methods fail because PDMS does not exhibit long-range fluidity at melting. We introduce an improved method to produce filaments of PDMS by a stepped temperature profile of the polymer as it cross-links from a fluid to an elastomer. By monitoring its warm-temperature viscosity, we estimate a window of time when its material properties are amendable to drawing into long filaments. The filaments pass through a high-temperature tube oven, curing them sufficiently to be harvested. These filaments are on the order of hundreds of micrometers in diameter and tens of centimeters in length, and even longer and thinner filaments are possible. These filaments retain many of the material properties of bulk PDMS, including switchable hydrophobicity. We demonstrate this capability with an automated corona-discharge patterning method. These patternable PDMS silicone filaments have applications in silicone weavings, gas-permeable sensor components, and model microscale foldamers.

Mode of cytotoxic action of nephrotoxic agents: oxidative stress and glutathione-dependent enzyme.

OBJECTIVE: To investigate the cytotoxic action of nephrotoxic agents using an in vitro renal cell model, focusing on the cellular oxidative status and a specific glutathione (GSH)-dependent enzyme, glyoxalase I (Gly-I). MATERIALS AND METHODS: Renal proximal tubular LLC-PK(1) cells were exposed to mercuric chloride, glycerol, cisplatin, gentamicin and cyclosporin A, and cell number/viability were determined. Oxidative stress was assessed by lipid peroxidation (LPO) assay, and Gly-I activity was measured by enzymatic method on a spectrophotometer. RESULTS: Both mercuric chloride (30 microm) and glycerol (2.5%) were highly toxic to LLC-PK(1) cells, inducing >90% cell death within 24 h. The remaining agents led to slightly >50% growth inhibition at 72 h. The LPO levels at 3 h in cells exposed to mercuric chloride or glycerol were approximately 2.5 times higher than that in controls. N-acetylcysteine (NAC), a potent antioxidant and precursor for GSH, almost completely (>95%) prevented renal cell death from mercuric chloride or glycerol. Gly-I activity was dependent on NAC and closely associated with cell viability. A approximately 65% loss in Gly-I activity by mercuric chloride/glycerol led to >90% cell death, while restoring a basal activity of Gly-I with NAC was accompanied by complete cell viability. CONCLUSIONS: The cytotoxic action of nephrotoxic agents appears to be triggered by oxidative stress, leading to Gly-I inactivation. As Gly-I plays a key role in cellular detoxification, its inactivation under oxidative stress probably becomes fatal to cells. However, cytoprotection provided with NAC is significant and might have implications in preventing renal cell injury mediated through nephrotoxic agents.

Synergistic potentiation of interferon activity with maitake mushroom d-fraction on bladder cancer cells.

OBJECTIVE: To examine whether the combination of interferon (IFN)-alpha and maitake mushroom D-fraction (PDF), a bioactive mushroom extract, might potentiate the anticancer activity of IFN-alpha in bladder cancer T24 cells in vitro. MATERIALS AND METHODS: Effects of recombinant IFN-alpha(2b) (0-50 000 IU/mL), PDF (0-700 microg/mL), or their combinations were assessed on T24 cell growth at 72 h. Cell cycle analysis and assays for double-stranded DNA-dependent protein kinase (DNA-PK) were performed to explore possible antiproliferative mechanism of these agents. RESULTS: IFN-alpha(2b) was able to induce a significant ( approximately 50%) growth reduction at 20 000 IU/mL, which further declined to approximately 66% at 50 000 IU/mL. PDF had no effects up to 200 microg/mL, but there was an approximately 20% and approximately 53% growth reduction at 400 and 700 microg/mL, respectively. When the varying concentrations of IFN-alpha(2b) and PDF were combined, 10 000 IU/mL of IFN-alpha(2b) combined with 200 microg/mL of PDF resulted in an approximately 75% growth reduction. This was accompanied by a G(1) cell cycle arrest, shown by cell cycle analysis. Concurrently, DNA-PK activity in IFN-alpha(2b)/PDF-treated cells was almost three-fold higher than controls. CONCLUSIONS: The combination of IFN-alpha(2b) (10 000 IU/mL) and PDF (200 microg/mL) reduced growth by approximately 75% in T24 cells. This appears to be due to a synergistic potentiation of these two agents, inducing a G(1) arrest with DNA-PK activation. Therefore, the IFN-alpha(2b)/PDF combination could trigger DNA-PK activation that may act on the cell cycle to cease cancer cell growth.

Possible disease remission in patient with invasive bladder cancer with D-fraction regimen.

Superficial bladder tumors are the most prevalent form of bladder cancers and transurethral resection is the primary surgical modality for those tumors. However, nearly 65% of patients will have tumor recurrence in five years while about 15% will have progression to muscle invasion. Thus, the primary therapeutic aim is to prevent multiple recurrences and progression to a more advanced, invasive disease. We here report an 87-year-old white male patient with invasive bladder cancer who received an unconventional oral regimen of D-fraction, the bioactive extract of Maitake mushroom (Grifola frondosa), following endoscopic transurethral resection of bladder tumor. Despite a high risk for disease recurrence, follow-up yet indicated no clinical evidence of progression of residual disease or recurrence of invasive cancer. It has been nearly two years but the patient remains remarkably well and appears to be in remission. To our knowledge, this is the first and only case report of possible disease remission in a bladder cancer patient after the two-year follow-up of D-fraction regimen, so that further studies with long terms are required for drawing a relevant conclusion. Nevertheless, it is conceivable that D-fraction is a natural agent that may have clinical implications in patients with superficial bladder tumors.

Possible immunotherapeutic potentiation with D-fraction in prostate cancer cells.

BACKGROUND: Prostate cancer remains the most common malignancy among elderly men and the second leading cause of cancer death in the United States. Although several conventional therapies are currently available, they have a low efficacy and the more effective treatment modalities need to be established. Interferons (IFNs) are one of such options known as immunotherapy and demonstrated their antitumor effects on certain cancer types. Yet such antitumor activity should be improved or potentiated to have the satisfactory outcomes. In fact, combination therapy has been proposed as an alternative approach and is being underway in human and animal studies. Accordingly, we studied whether the combination of IFN-alpha and D-fraction (PDF), a bioactive mushroom extract, might potentiate anticancer activity of IFN-alpha in prostate cancer PC-3 cells in vitro. RESULTS: Potential effects of recombinant IFN-alpha(2b) (0-100,000 IU/ml), PDF (0-1,000 microg/ml), or their combinations were assessed on the growth of PC-3 cells at 72 h. Cell cycle analysis using a flow cytometer and Western blot analysis were performed to explore antiproliferative mechanism of these agents. The dose-dependent study showed that IFN-alpha(2b) up to 20,000 (20 K) IU/ml had no significant effects, but >60% growth reduction was attained 60%) down-regulated in IFN/PDF-treated cells. CONCLUSION: The combination of IFN-alpha(2b) (10 K IU/ml) and PDF (250 microg/ml) is capable of inducing a approximately 65% reduction in PC-3 cell growth. This appears to be due to a synergistic potentiation of two agents, leading to a G1 cell cycle arrest. Thus, it is conceivable that PDF may potentiate IFN-alpha(2b) activity, improving immunotherapy for prostate cancer.

Central control of renal sodium-phosphate (NaPi-2) transporters.

Regulation of phosphate (Pi) reabsorption occurs through the up- and downregulation of the renal type-II sodium Pi cotransporters (NaPi-2). Recently, renal NaPi2-type expression has been identified in areas of the brain. The present study determined whether brain NaPi-2 is regulated by dietary Pi and whether the behavioral and renal adaptations to low-dietary Pi are controlled centrally. NaPi-2-like expression in the third ventricle (3V) and amygdala of juvenile Wistar rats was regulated by dietary Pi, as in the kidneys. When cerebrospinal fluid (CSF) Pi concentration was elevated by 3V injections of Pi in rats fed low-Pi diet (LPD), the behavioral and renal adaptations to LPD were abolished. Most importantly, NaPi-2 expression was markedly reduced not only in the brain, but also renal proximal tubules, despite the low plasma Pi milieu. This was confirmed by the significant reduction in the transport maximum for Pi (from 8.1+/-0.2 in LPD + veh 3V to 1.7+/-0.1 micromol Pi/ml glomerular filtration rate in LPD + 3V Pi, P < 0.001). These findings indicate that NaPi-2-like transporters in the brain are regulated by both dietary Pi and CSF Pi concentrations, and most significantly, that the central Pi milieu can regulate renal NaPi-2 expression. We hypothesize that central 3V NaPi-2 transporters may act as Pi sensors and help regulate both brain and whole body Pi homeostasis.