Can Ultrafiltration Occur with a Hypo-Osmolar Solution in Peritoneal Dialysis?: The Role for ‘Colloid’ Osmosis

1993 ◽  
Vol 85 (4) ◽  
pp. 495-500 ◽  
Author(s):  
Chandra D. Mistry ◽  
Ram Gokal
Keyword(s):  
Molecular Weight ◽  
Peritoneal Dialysis ◽  
Polymer Solution ◽  
Corn Starch ◽  
Average Molecular Weight ◽  
Dialysis Solution ◽  
Wide Range ◽  
Glucose Polymer ◽  
Metabolic Correction

1. In peritoneal dialysis the removal of excess body water (ultrafiltration) is traditionally achieved by means of dialysis solution made hypertonic to plasma by the addition of an osmotic agent. In vitro, the osmotic flow may be directed against the osmolality gradient by using a hypo-osmolar solution, but this phenomenon has not previously been applied to clinical peritoneal dialysis. 2. The ultrafiltration performances of hypo-osmolar dialysis solutions containing a high-molecular-weight glucose polymer (weight average molecular weight 22 000), isolated by fractionation of hydrolysed corn starch, were compared with those of hypertonic glucose solutions over a 12 h exchange in 11 patients well established on continuous ambulatory peritoneal dialysis. 3. Five per cent (272 +1.1 mosmol/kg) and 7.5% (277 + 2.0 mosmol/kg) glucose polymer solutions produced net ultrafiltration of 243 +53 and 526 +59 ml that were significantly greater than the ultrafiltration of −48 +96 and 223 +84 ml associated with 1.36% (339 +1.9 mosmol/kg) and 2.27% (393 +3.2 mosmol/kg) glucose solutions, respectively. The net ultrafiltration with 10% glucose polymer (284 +2.0 mosmol/kg) and 3.86% glucose (482 + 1.6 mosmol/kg) solutions were similar (699 +48 versus 708 +82 ml). 4. The transperitoneal absorption of glucose polymer was substantially lower than that of glucose solutions as was the potential calorie load per millilitre of ultrafiltrate. 5. The addition of 0.35% glucose (molecular weight 180) to 7.5% glucose polymer solution raised the dialysate osmolality to an iso-osmolar level (299 +0.8 mosmol/kg) and produced ultrafiltration which was 29% greater than with 7.5% glucose polymer solution alone. 6. The demonstration of ultrafiltration with hypo-osmolar dialysate represents an important advance towards the formulation of a physiological iso-osmolar dialysis solution, which may have long-term benefits over the conventional hypertonic solutions. The iso-osmolar combination of ‘colloid’ and ‘crystalloid’ osmotic agents looks promising with a potential for a wide range of ultrafiltration capabilities as well as metabolic correction.

scholarly journals Low-Polydispersity Glucose Polymers as Osmotic Agents for Peritoneal Dialysis

2015 ◽  
Vol 35 (4) ◽  
pp. 428-435
Author(s):  
John K. Leypoldt ◽  
Catherine M. Hoff ◽  
Alp Akonur ◽  
Clifford J. Holmes
Keyword(s):  
Peritoneal Dialysis ◽  
Standard Deviation ◽  
Average Molecular Weight ◽  
Fluid Collection ◽  
Experimental Studies ◽  
Total Carbohydrate ◽  
Glucose Polymer ◽  
New Zealand White Rabbits ◽  
Osmotic Agent ◽  
Osmotic Agents

♦BackgroundPeritoneal dialysis (PD) solutions containing icodextrin as the osmotic agent have advantages during long dwells. The glucose polymers that constitute icodextrin are a heterogeneous mix of molecules with a polydispersity [ratio of weight-average to number-average molecular weight (Mw/Mn)] of approximately 2.6. The present study evaluates whether modifications in the polydispersity and concentration of glucose polymers can improve ultrafiltration (UF) without an associated increase in carbohydrate absorption (CA).♦MethodsComputer simulations using a three-pore model of peritoneal transport during a long dwell in PD patients predict that, in general, compared with 7.5% icodextrin, glucose polymers with a Mw greater than or equal to 7.5 kDa, a polydispersity less than 2.6, and concentrations greater than 7% could achieve higher UF without higher CA. Based on the simulations, we hypothesized that, compared with 7.5% icodextrin, glucose polymers with a Mw of 18 – 19 kDa and a polydispersity of 2.0 at 11% concentration could achieve higher UF without a higher CA. We tested this hypothesis in experimental studies using 8-hour dwells in New Zealand White rabbits. In those studies, UF was measured by complete fluid collection, and CA was measured by subtracting the total carbohydrate in the collected fluid from the carbohydrate initially infused.♦ResultsThe UF was higher with 11% 19 kDa glucose polymer than with 7.5% icodextrin (mean ± standard deviation: 89 ± 31 mL vs 49 ± 15 mL; p = 0.004) without higher CA (5.2 ± 0.9 g vs 5.0 ± 0.9 g, p = 0.7). Similar results were seen with the 11% 18 kDa glucose polymer, which, compared with 7.5% icodextrin, resulted in higher UF (mean ± standard deviation: 96 ± 18 mL vs 66 ± 17 mL; p < 0.001) without higher CA (4.8 ± 0.7 g vs 5.2 ± 0.6 g, p = 0.2).♦ConclusionsThe findings demonstrate that, compared with 7.5% icodextrin solution, long-dwell PD solutions containing 11% glucose polymers with a Mw of 18–19 kDa and a polydispersity of 2.0 can provide higher UF without higher CA.

In vitro effects of glucose polymer-containing peritoneal dialysis fluids on phagocytic activity

1997 ◽  
Vol 29 (2) ◽  
pp. 246-253 ◽  
Author(s):  
Stefan Thomas ◽  
Uwe Schenk ◽  
Frank-Peter Fischer ◽  
Thomas Mettang ◽  
Jutta Passlick-Deetjen ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Phagocytic Activity ◽  
Glucose Polymer ◽  
In Vitro Effects ◽  
Dialysis Fluids

L-2-Oxothiazolidine-4-Carboxylate: An Agent that Modulates Lipopolysaccharide-Induced Peritonitis in Rats

2002 ◽  
Vol 22 (3) ◽  
pp. 293-300 ◽  
Author(s):  
Katarzyna Korybalska ◽  
Katarzyna Wieczorowska–Tobis ◽  
Alicja Polubinska ◽  
Justyna Wisniewska ◽  
James Moberly ◽  
...  
Keyword(s):  
Peritoneal Dialysis ◽  
Peritoneal Cell ◽  
Cellular Damage ◽  
Dialysis Fluid ◽  
Acute Peritonitis ◽  
Cell Counts ◽  
Dialysis Solution ◽  
Peritoneal Leukocytes ◽  
Peritoneal Function

Objective L-2-Oxothiazolidine-4-carboxylate (OTZ), a cysteine precursor, is a substrate for intracellular glutathione synthesis. As shown previously, OTZ prevents free-radical induced cellular damage during in vitro simulation of peritoneal dialysis. In the present study, we examined the effect of adding OTZ to peritoneal dialysis solution on peritoneal function and structure during lipopolysaccharide (LPS)-induced peritonitis in rats. In addition, we studied the effects of pretreatment with OTZ (given orally) on the effects of LPS-induced peritonitis in rats. Methods Peritonitis was induced in rats by adding LPS (5 μg/mL) to the dialysis fluid. For acute experiments, rats were exposed to a single infusion of dialysis solution containing LPS or to LPS plus 5 mmol/L OTZ; peritoneal cell counts and permeability were determined after 4 hours. Alternatively, rats were pretreated with OTZ added to the drinking water (0.1%) for 10 days prior to infusion of LPS. For chronic experiments, peritoneal dialysis was performed over a 3-week period in rats with implanted peritoneal catheters. On days 8, 9, and 10 of the experiment, the rats were infused intraperitoneally with solution containing LPS (5 μg/mL), or LPS plus 5 mmol/L OTZ, to induce acute peritonitis. At the end of dialysis (10 days after the episodes of peritonitis), peritoneal function was assessed using a peritoneal equilibration test (PET), and peritoneal biopsies were taken to assess effects on peritoneal morphology. Results In the acute experiments, exposure to LPS led to increased peritoneal cell counts (+61% vs control, p < 0.05) and enhanced permeability of the peritoneum, leading to a loss in ultrafiltration (–63%, p < 0.0005). The glutathione concentration in peritoneal leukocytes also decreased during acute peritonitis (–31%, p < 0.05). During LPS-induced peritonitis, OTZ prevented the increase in dialysate cell count and the decrease in cellular glutathione content. Simultaneous administration of OTZ did not prevent the increased peritoneal permeability induced by LPS. However, in rats pretreated with OTZ, LPS-induced permeability to protein was significantly lower than in the nontreated animals (0.049 ± 0.011 vs 0.087 ± 0.034, p < 0.05). In the chronic experiments, LPS-induced peritonitis did not lead to any functional differences in peritoneal transport at the end of 3 weeks of dialysis. However, LPS-induced peritonitis led to increased thickness of the peritoneum and neovascularization within peritoneal interstitium compared to peritonitis-free animals. In contrast to the LPS-treated animals, the peritoneum of the rats exposed to LPS in the presence of OTZ was of a thickness similar to that in the control rats. Conclusion Supplementation of dialysis fluid with OTZ prevented changes in cellular glutathione levels and dialysate cell counts during acute peritonitis in rats. During chronic dialysis in rats exposed to intermittent peritonitis episodes, OTZ prevented increased thickening and neovascularization of the peritoneum. Our results suggest this may help to protect the peritoneal membrane during episodes of peritonitis.

scholarly journals Valsartan ameliorates high glucose-induced peritoneal fibrosis by blocking mTORC1 signaling

2020 ◽  
Vol 245 (11) ◽  
pp. 983-993 ◽  
Author(s):  
Jing Liu ◽  
Yuan Feng ◽  
Cheng Sun ◽  
Wei Zhu ◽  
Qing-Yan Zhang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Peritoneal Dialysis ◽  
Protein Expression ◽  
High Glucose ◽  
Collagen I ◽  
Peritoneal Fibrosis ◽  
Dialysis Solution ◽  
Mtorc1 Pathway ◽  
Peritoneal Dialysis Solution

Our previous study demonstrated that the mammalian target of rapamycin complex 1 (mTORC1) pathway is activated in peritoneal fibrosis under high glucose condition. This study aimed to investigate whether valsartan inhibits high glucose-induced peritoneal fibrosis via decreasing the activity of the mTORC1 pathway. We used high glucose peritoneal dialysis solution in a mouse peritoneal dialysis model to induce peritoneal fibrosis in vivo and high glucose in human peritoneal mesothelial cells (HPMCs) to stimulate extracellular matrix accumulation in vitro. After injections of peritoneal dialysis solution containing 4.25% glucose for four weeks, mice showed typical features of peritoneal fibrosis, including markedly increased peritoneal thickness, excessive matrix deposition, increased peritoneal permeability, and higher expression of extracellular matrix proteins, such as α-smooth muscle actin (α-SMA) and collagen I. Oral gavage of valsartan significantly ameliorated these pathological changes at both week 6 and week 8. These effects of valsartan were closely correlated with a decrease in the activation of the mTORC1 signal, which was mediated by the downregulation of the protein expression of phosphorylated (p)-mTOR, p-eukaryotic initiation factor 4E-binding protein 1, and p-p70 S6 kinase 1. Further research showed that the protein expression of mTORC1 signal was positively correlated with the expression of both α-SMA and collagen I in the peritoneum. In vitro, high glucose increased the protein expression of α-SMA and collagen I in a dose-dependent manner, while valsartan significantly inhibited high glucose-induced extracellular matrix accumulation in HPMCs. The effect was also accompanied by a decrease in the activation of the mTORC1 signal. Furthermore, the mTOR agonist MHY1485 reversed the downregulation of extracellular matrix components in HPMCs, even in the presence of valsartan. We conclude that valsartan exerts a protective effect against high glucose-induced peritoneal fibrosis via suppressing the activity of the mTORC1 pathway. Impact statement Our study provided new insight into the mechanism underlying the preservation of the peritoneum by valsartan. The results demonstrated that the mice receiving chronic high glucose (HG) peritoneal dialysis solution infusion showed a typical feature of peritoneal fibrosis (PF), as well as higher expression of α-smooth muscle actin (α-SMA) and collagen I. In vitro, HG increased the protein expression of α-SMA and collagen I in a dose-dependent manner, while valsartan significantly ameliorated these pathological changes. Interestingly, there was a parallel decrease in the activity of mammalian target of rapamycin complex 1 (mTORC1) and the protein expression levels of α-SMA and collagen I upon treatment with valsartan in vivo and in vitro. Moreover, the mTOR agonist MHY1485 reversed the downregulation of α-SMA and collagen I in vitro, even in the presence of valsartan. Altogether, our findings reported for the first time that valsartan exerts a protective effect against HG-induced PF by inhibiting the activity of the mTORC1 pathway.

scholarly journals Chitin, Chitosan, and Submicron-Sized Chitosan Particles Prepared from Scylla serrata Shells

2020 ◽  
Vol 2 (2) ◽  
pp. 139-149
Keyword(s):  
Molecular Weight ◽  
Sodium Tripolyphosphate ◽  
Average Molecular Weight ◽  
Value Added ◽  
Scylla Serrata ◽  
Mud Crab ◽  
Practical Applications ◽  
Degree Of Acetylation ◽  
Wide Range ◽  
Chitin And Chitosan

Extraction of chitin from mud crab (Scylla serrata) shells, involving demineralization and deproteinization, and deacetylation of the extracted chitin to form chitosan were investigated. The mud crab chitin and chitosan were obtained with a good yield (16.8% and 84.7% based on dried weight basis). The physicochemical properties, functional groups, molecular weight, and degree of acetylation of the chitin and chitosan were characterized. The surface morphology, the orientation arrangement of polysaccharide strands, and crystallinity of the chitin and chitosan prepared from the mud crab shells were investigated. SEM, FTIR, and XRD analyses demonstrated that the chitin consists of micron-sized fibrils, belonging to α from with the crystallinity of 60.1%. The chitosan has a viscosity-average molecular weight of 6.83 kDa with the degree of acetylation being 9.6% and the crystallinity of 73.8%. The chitosan was successfully fabricated into submicron-sized particles using top-down ionotropic gelation, microwave, and microemulsion methods, employing sodium tripolyphosphate, potassium persulfate, and glutaraldehyde as reagents, respectively. Overall, the results indicated that the preparation of chitin, chitosan, and submicron-sized chitosan particles from mud crab shells could open the opportunity for the value-added seafood waste to be utilized in a wide range of practical applications.

scholarly journals Fighting SARS-CoV-2 with green seaweed Ulva sp. extract: extraction protocol predetermines crude ulvan extract anti-SARS-CoV-2 inhibition properties in in vitro Vero-E6 cells assay

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12398
Author(s):  
Shai Shefer ◽  
Arthur Robin ◽  
Alexander Chemodanov ◽  
Mario Lebendiker ◽  
Robert Bostwick ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chemical Composition ◽  
Antiviral Activity ◽  
Cytopathic Effect ◽  
Average Molecular Weight ◽  
Ammonium Oxalate ◽  
Extraction Protocol ◽  
Reduction Assay ◽  
Green Seaweed

Due to the global COVID-19 pandemic, there is a need to screen for novel compounds with antiviral activity against SARS-COV-2. Here we compared chemical composition and the in vitro anti- SARS-COV-2 activity of two different Ulva sp. crude ulvan extracts: one obtained by an HCl-based and another one by ammonium oxalate-based (AOx) extraction protocols. The composition of the crude extracts was analyzed and their antiviral activity was assessed in a cytopathic effect reduction assay using Vero E6 cells. We show that the extraction protocols have a significant impact on the chemical composition, anti- SARS-COV-2 activity, and cytotoxicity of these ulvan extracts. The ulvan extract based on the AOx protocol had a higher average molecular weight, higher charge, and 11.3-fold higher antiviral activity than HCl-based extract. Our results strongly suggest that further bioassay-guided investigation into bioactivity of compounds found in Ulva sp. ulvan extracts could lead to the discovery of novel anti-SARS-CoV-2 antivirals.

A novel dextrin produced by the enzymatic reaction of 6-α-glucosyltransferase I: The effect of non-reducing ends of glucose with by α-1,6 bonds on the retrogradation inhibition of high molecular weight dextrin

2021 ◽  
Author(s):  
Akiko Yasuda ◽  
Manabu Miyata ◽  
Osamu Sano ◽  
Tatsufumi Sogo ◽  
Seiichiro Kishishita ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Corn Starch ◽  
Average Molecular Weight ◽  
Enzymatic Reaction ◽  
Amperometric Detection ◽  
Exchange Chromatography ◽  
Weight Average Molecular Weight ◽  
Waxy Corn Starch ◽  
Waxy Corn

Abstract We prepared a high-molecular-weight modified dextrin (MWS-1000) from a partial hydrolysate of waxy corn starch with a weight average molecular weight of 1 × 106 (WS-1000) using Paenibacillus alginolyticus PP710 α-glucosyltransferase. The gel permeation chromatography showed that the weight average molecular weight of MWS-1000 was almost the same as that of WS-1000. The side chain length of WS-1000 and MWS-1000 after isomaltodextranase digestion were also shown to be similar to each other by high performance anion exchange chromatography with pulsed amperometric detection. Since MWS-1000 confirmed the presence of α-1,6 bonds by enzyme digestibility, methylation, and 1H-NMR analyses, it was presumed that the structure of MWS-1000 was based on the introduction of α-1,6 glucosyl residues at the non-reducing ends of the partial hydrolysate of waxy corn starch. Furthermore, the MWS-1000 solution was not retrograded even during refrigerated storage or after repeated freeze-thaw cycles.

Charged Polymers as Osmotic Agents for Peritoneal Dialysis

1985 ◽  
Vol 55 ◽  
Author(s):  
Zbylut J. Twardowski ◽  
Karl D. Nolph ◽  
Ramesh Khanna ◽  
Hannelore Hain ◽  
Harold Moore ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Peritoneal Dialysis ◽  
Colloid Osmotic Pressure ◽  
Small Molecular Weight ◽  
Plasma Substitutes ◽  
Chemically Modified ◽  
Charged Polymers ◽  
Gelatin Derivative ◽  
Osmotic Agents

ABSTRACTA sustained ultrafiltration during long-dwell peritoneal dialysis exchanges cannot be achieved with rapidly absorbable small molecular weight substances such as commonly used glucose. Uncharged polymeric substances are absorbed slower, but yield insufficient osmotic driving force because osmolality is inversely proportional to the molecular weight.Charged polymers induce colloid osmotic pressure not only because of the molecules themselves, but also by ions kept in the peritoneal cavity by opposite charges of polymers. In anin vitromodel of peritoneal dialysis, a sustained ultrafiltration has been achieved with several synthetic polymers including polyacrylate, dextran sulfate and polyethylenimine. However, these polymers were locally toxic to the peritoneal membrane when tested in rats and rabbits.Chemically modified gelatin derivatives, such as polygelin, exypolygelatin, and succinylated gelatin are widely used in Europe as plasma substitutes. They are metabolized and have proven to be systemically non-toxic. These gelatin derivative solutions were tested in rat models of peritoneal dialysis. Up to 10% solutions achieved sustained ultrafiltration at the rate proportional to the concentration and no untoward systemic or local effects on the peritoneum were observed. Absorption of gelatin molecules ranged from 40–60% of the infused amounts. The results of the studies indicate that gelatin derivitives have potential for clinical use as osmotic agents in long-dwell peritoneal dialysis exchanges if the absorption rates in humans are markedly lower than in rats.

In vitro synthesis of glycogen: the structure, properties, and physiological function of enzymatically-synthesized glycogen

Biologia ◽  
2011 ◽  
Vol 66 (3) ◽  
Author(s):  
Hideki Kajiura ◽  
Hiroki Takata ◽  
Tsunehisa Akiyama ◽  
Ryo Kakutani ◽  
Takashi Furuyashiki ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Large Scale ◽  
Glycogen Synthesis ◽  
Average Molecular Weight ◽  
Spherical Particles ◽  
Average Chain Length ◽  
Scale Production ◽  
In Vitro Synthesis

AbstractThis review describes a new enzymatic method for in vitro glycogen synthesis and its structure and properties. In this method, short-chain amylose is used as the substrate for branching enzymes (BE, EC 2.4.1.18). Although a kidney bean BE and Bacillus cereus BE could not synthesize high-molecular weight glucan, BEs from 6 other bacterial sources produced enzymatically synthesized glycogen (ESG). The BE from Aquifex aeolicus was the most suitable for the production of glycogen with a weight-average molecular weight (M w) of 3,000–30,000 k. The molecular weight of the ESG is controllable by changing the concentration of the substrate amylose. Furthermore, the addition of amylomaltase (AM, EC 2.4.1.25) significantly enhanced the efficiency of this process, and the yield of ESG reached approximately 65%. Typical preparations of ESG obtained by this method were subjected to structural analyses. The average chain length, interior chain length, and exterior chain length of the ESGs were 8.2–11.6, 2.0–3.3, and 4.2–7.6, respectively. Transmission electron microscopy and intrinsic viscosity measurement showed that the ESG molecules formed spherical particles. Unlike starch, the ESGs were barely degraded by pullulanase. Solutions of ESG were opalescent (milky-white and slightly bluish), and gave a reddishbrown color on the addition of iodine. These analyses revealed that ESG shares similar molecular shapes and solution properties with natural-source glycogen. Moreover, ESG had macrophage-stimulating activity and its activity depends on the molecular weight of ESG. We successfully achieved large scale production of ESG. ESG could lead to new industrial applications, such as in the food, chemical, and pharmaceutical fields.

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