Polyethelene Glycol Research Articles

Investigation of the effect of sol processing parameters on the photoelectrical properties of dye-sensitized TiO 2 solar cells

Sol-gel spin-coating method has been explored to prepare nano-crystalline TiO 2 films for dye-sensitized TiO 2 solar cell application. Effects of evaporation temperature at which the sol is concentrated and addition of polyethelene glycol (PEG) to the sol at different concentrations on film thickness, surface morphology and solar cell performance are studied. Conversion efficiency is found to increase with PEG addition up to 40 % by weight of TiO 2 and then decrease with further addition due to the development of cracks in the films. Higher conversion efficiency has been obtained with the sol concentrated at 40°C than at room temperature (30°C) after which it is found to decrease with increase in temperature due to higher degree of agglomeration caused by faster rate of evaporation. Further, it is observed that though the photocurrent and efficiency gradually increase with thickness at relatively lower thicknesses, a saturation in the photocurrent occurs at higher thicknesses.

Microperfusion techniques for long-term hypothermic preservation

Background The aim of this study was to compare several methods of hypothermic heart preservation. Methods We preserved isolated pig hearts for 24 hours in cold cardioplegia (4° C), using either continuous microperfusion (Group I) or simple storage (Group II), and with a new preservative solution (NPS, groups IA and IIA) vs St. Thomas’ solution (groups IB and IIB). The main characteristics of the NPS include (1) prevention of cell swelling with polyethelene glycol (PEG), (2) low calcium and magnesium, and (3) presence of metabolic substrates, such as glucose, insulin, pyruvate, aspartate, alanyl-glutamine, and membrane stabilization compounds such as ethanol and chlorpromazine. Results The 4 above groups were compared with hearts harvested and immediately reperfused (control group). During preservation, only Group IB showed significant edema (40% ± 8.4% water gain). Adenylate charge was 25% to 50% higher in microperfused Groups IA and IB (0.678 ± 0.049 and 0.795 ± 0.071, respectively) as compared with simple-storage groups IIA and IIB (0.605 ± 0.048 and 0.524 ± 0.160, respectively). Ultrastructural analysis showed that tissue injury occurred mainly in Group IIB (altered mitochondria, chromatin clumping). Functional data showed better recovery of NPS groups as compared with St. Thomas groups: coronary flow was identical in Group IB and control (57.8 ± 22 and 56.6 ± 14 ml/min/100 g, respectively), and in IA > IB ( p < 0.001) and IIA > IIB ( p < 0.01); the rate pressure products were higher in NPS groups compared with St. Thomas groups (IA > IB, p < 0.01); IIA > IIB, p < 0.05). Conclusions The microperfusion method associated with the NPS provides excellent protection in long-term hypothermic heart preservation.

Recombinant human thyroid peroxidase expressed in insect cells is soluble at high concentrations and forms diffracting crystals.

Human thyroid peroxidase (TPO), the key enzyme in thyroid hormone synthesis, can be produced in active form in the High Five insect cell line and when purified from the cell culture medium is soluble at concentrations of up to 18 mg/ml. This contrasts to a recent report in which human TPO produced in insect cells was found to be insoluble at high concentrations. Our concentrated TPO grows trigonal trapezohedral crystals of up to 0.5 mm in length in a vapour diffusion apparatus using polyethelene glycol as a precipitant. The crystals diffract X-rays to a 6 A resolution and the diffraction data from the crystals have been analysed giving unit cell dimensions. A potential molecular replacement solution has been identified using myeloperoxidase (MPO) as a phasing model.

Factors Relating to Seedling Emergence in Spring Wheat

Spring wheat (Triticum aestivum L.) is cultivated in the northern part of Japan. Although the vigorous early growth of spring wheat is desirable, the rapid and uniform emergence of seedlings is reduced by adverse environmental effects, such as excessive soil moisture and low temperature. Analyses of correlations between field emergence day and germination traits under low temperature, after treatment with polyethelene glycol (PEG) and after flooding treatment of 44 varieties from Japan and other countries indicated a general absence of interrelationships. Moreover, there was no significant correlation between field emergence days in trials in 1996 and 1997. Small and large seeds of Haruyutaka harvested in 1994 and 1996 were hand-sown at depths of 3 cm and 10 cm without fertilizer and with standard fertilizer in brown forest soil in a field of the Tokyo University of Agriculture in Hokkaido. The superiority of large seeds over small seeds was demonstrated by the production of more shoot dry matter with sowing at a depth of 3 cm and by the number of emerged plants with sowing at a depth of 10 cm. Although the coefficients of correlation between field emergence day and germination traits of the wheat varieties were low, a sowing method that optimized seedling growth in the field was demonstrated in this experiment.

Crystallization of the Secondary Alcohol Dehydrogenase from Thermoanaerobacter ethanolicus 39E.

Abstract: The secondary alcohol dehydrogenase from the thermophile Thermoanaerobacter ethanolicus 39E has been crystallized at 40°C by vapour difussion using polyethelene glycol as a precipitant. The orthorhombic crystals belong to the space group P 21212 with cell constants of a=170.0A, b=125.7A and c=80.5A.A native X-ray diffraction data set has been collected to 2.7A resolution .

Pulmonary absorption of polyethylene glycolated recombinant human granulocyte-colony stimulating factor (PEG rhG-CSF)

The pulmonary delivery of recombinant human granulocyte — colony stimulating factor (rhG-CSF, 18.8kDa) and two polyethelene glycol (PEG) conjugates of rhG-CSF, (P1, 81.5 kDa and P2, 146.8 kDa) was investigated in the rat. Doses of 50 and 500 μg/kg were administered by intratracheal instillation (IT) or 25 and 250 μg/kg by intravenous injection (IV). Additional IV doses of 50, 100 and 1000 μg/kg rhG-CSF were given to assess the effect of dose on clearance. Blood samples were removed at regular time points from an indwelling jugular catheter and analyzed directly for total white blood cell counts (WBC). Plasma was assayed for protein by an enzyme immuno assay. The pharmacokinetics and pharmacological response were determined for both routes of administration. Low doses of the protein effected a short-lived response that peaked at around 12 h while the higher doses induced a more profound response that peaked at approximately 24 h post dose. The PEGylated proteins generated a more intense and extended WBC response relative to rhG-CSF alone with the order being P2 > P1 > rh-G-CSF. Pulmonary administration of the proteins also induced a similar order of response implying that the PEGylated proteins were being absorbed intact. The IV concentration vs. time profiles declined biexponentially for both the PEGs and the rhG-CSF. Plasma clearance (Cl p) was dose dependent and ranged from 0.55ml/min/kg (1000 μg/kg) to 0.81ml/min/kg (25 μg/kg) for rhG-CSF. The clearance rates of P1 and P2 (0.28 and 0.19 ml/min/kg [25μg/kg]) correlated inversely with the respective degree of PEGylation. Estimates of dose and weight normalized bioavailability ranged from 2.6 to 27.4% for the instilled solutions. There was a trend toward increased availability as the size of the protein decreased. However, the absorption of rhG-CSF at the two doses was markedly different (3.0 ± 0.5 [50μg/kg] vs. 27.4 ± 8.7% [500 μg/kg], P < 0.05, n = 6) suggesting that absorption is influenced by other clearance mechanism(s). Western analysis for rhG-CSF in bronchoalveolar lavage fluid revealed additional small molecular weight bands suggesting that rhG-CSF may be partially degraded in the lung.

Effect of desalivation on water and sodium chloride intake in rats

Desalivate rats consumed significantly less water than sham-operated rats in response to acute challenges with a variety of dipsogens, including polyethelene glycol (PEG), isoproterenol, serotonin, and an angiotensin I converting enzyme inhibitor (CEI). Nonsignificant reductions were recorded after treatments with either angiotensin II or hypertonic NaCl. Meal-related hyperdipsia, and resultant possible hyperhydration, of desalivate rats does not account fully for these reductions in experimental thirsts. The mean 24-h intake of three concentrations of NaCl, in choice with water, showed no difference in the preferences for NaCl of desalivate and sham-operated animals. During chronic administration of CEIs, both desalivate and sham-operated rats showed comparable induction of NaCl appetite.

Fecal osmotic gap and pH in experimental diarrhea of various causes

Although the osmotic gap of fecal fluid is often used to distinguish osmotic diarrhea from secretory diarrhea, there has never been a scientific evaluation of the validity of this concept. Similarly, although a low fecal fluid pH value is used to indicate that diarrhea is mediated by carbohydrate malabsorption, the validity of this method is unproven. Therefore, in the present study, diarrhea was induced in normal subjects by different mechanisms and fecal fluid osmotic gap (using an assumed fecal fluid osmolality of 290 mOsm/kg) and pH were measured. In secretory diarrhea caused by phenolphthalein, the osmotic gap was always <50 mOsm/kg, whereas in osmotic diarrhea caused by polyethelene glycol, magnesium hydroxide, lactulose, and sorbitol, the osmotic gap always exceeded 50 mOsm/kg. In osmotic diarrhea caused by sodium sulfate, the fecal fluid osmotic gap was <50 mOsm/ kg, but phenolphthalein-induced secretory diarrhea could be distinguished from sodium sulfate-induced osmotic diarrhea by the fecal chloride concentration. When diarrhea was caused by carbohydrate malabsorption (lactulose or sorbitol), the fecal fluid pH was always <5.6 and usually <5.3; by contrast, other causes of diarrhea rarely caused a fecal pH as low as 5.6 and never caused a pH <5.3. It is concluded that measurement of fecal fluid osmotic gap and pH can distinguish various mechanisms of experimental diarrhea in normal subjects. The concepts on which these tests are based are therefore verified experimentally.

Preoperative bowel preparation

A survey of 500 clinically active, board-certified colon and rectal surgeons in the United States and Canada was conducted to obtain data regarding current methods of bowel preparation for elective colorectal surgery. A review of recent publications on preoperative bowel preparation was used to compare the current literature recommendations with the actual practice among the group surveyed. Responses were received from 352 of 500 colorectal surgeons to whom questionnaires were sent (70 percent response rate). All respondents used a mechanical preparation and some form of antibiotics. The favorite antibiotic regimen was oral antimicrobials combined with systemic antibiotics (88 percent). Concomitant administration of oral neomycin-erythromycin base and a systemic second generation cephalosporin active against both anaerobic and aerobic colonic bacteria, together with oral polyethelene glycol electrolyte mechanical colonic cleansing, was the most popular method of preoperative bowel preparation (58 percent). The second most frequent method of mechanical bowel cleansing consisted of conventional enemas, dietary restrictions, and cathartic preparations (36 percent). Mannitol solution (5 percent), and whole-gut irrigation per nasogastric tube (1 percent) were the least popular methods of mechanical bowel cleansing. The literature supports the current methods of preoperative bowel preparation used by the vast majority of surgeons surveyed.

Whole-gut lavage in children using an iso-osmolar solution containing polyethelene glycol (golytely)

Whole-gut irrigation with an iso-osmolar solution was assessed in 53 children. The lavage was well tolerated without evidence of fluid or electrolyte shift. The rate of infusion to achieve a clear bowel within six to ten hours was 25 to 35 mL/kg/h.

Factors Influencing Bitterweed Seed Germination

Factors Influencing Bitterweed Seed Germination

PEG determinations in urine, plasma, and various protein solutions

Polyethelene glycol is determined in a variety of biologic fluids. A stable, accurate, and sensitive method is described which is useful when PEG is used for protein purification, and in physiologic function and pharmacologic mechanism studies.

Effect of Different Osmotic Potentials of Media on Germination of Three Safflower Varieties

AbstractThe effect of osmotic potentials, 0 to −13.5 atm (−1.37 M Pa), on the germination of three safflower varieties (Carthamus tinctorius L.) was studied at a controlled temperature (30±2°C) using a non‐electrolyte substance, polyethelene glycol 6000. The varieties were cv. Ute, cv. Iranian local 3151, and cv. Iranian local 2811. The percent germination of the three varieties averaged over all osmotic potentials were: 86, 77 and 61 for local 3151, local 2811 and “Ute”, respectively. The Ute variety had the highest, and the local 3151 variety had the lowest rate of germination reduction. The variations among the varieties in the percent and rate of germination were due to osmotic effects of the media.