Polyvinyl Pyrrolidine Research Articles

Synthesis of a mesoporous silica hollow microsphere using polyvinyl alcohol

A mesoporous silica hollow microsphere was synthesized in the presence of polyvinyl alcohol for the first time. The synthesized material was characterized by various instrumental techniques such as small-angle X-ray scattering, scanning electron microscopy, transmission electron microscopy, N 2 adsorption measurement and Fourier transform infrared spectroscopy. I have succeeded in incorporating an Ultraviolet ray absorber, 2, 2´, 4, 4´ tetrahydroxy benzophenone by mixing it after synthesis. However an attempt to incorporate by mixing before synthesizing it changes the morphology. In addition to polyvinyl alcohol, the use of other polymers such as polyvinyl pyrrolidine and polyethylene glycol also changes the morphology into dry leaves or fibers.

Synthesis and characterization of polyvinylpyrrolidine assisted tantalum pentoxide films

Micron thick tantalum pentoxide (Ta 2O 5) films have been proposed as thermal insulating layers in microchemical systems, but so far it has been difficult to deposit thick enough films over complex substrates. So far sol–gel films cracked upon heating whenever the film thicknesses were above 350 nm. A 350 nm thick film is too thin for effective insulation. Other techniques are not suitable for coating the complex structures associated with microchemical systems. In this paper we report sol–gel synthesis of 1.6 μm thick tantalum pentoxide (Ta 2O 5) films. The films are almost crack free, and adhere to silicon surfaces even upon flashing to 900 °C. The key to the synthesis is the addition of Polyvinylpyrrolidine (PVP) to the sol. Films grown in the absence of PVP all show cracks upon calcination to 900 °C while few cracks are seen with PVP. X-ray diffraction and Fourier transform infra red analysis show that orthorhombic Ta 2O 5 is formed in all cases. X-ray photoelectron spectroscopy shows the O:Ta ratio to be 2.8:1. This shows that sol–gel is a viable process for making the micron thick films of Ta 2O 5 needed as insulators for microchemical systems.

Synthesis of mesoporous silica nanosphere using different templates

Synthesis of mesoporous silica nanosphere were carried out using polyvinyl pyrrolidine and different templates with surfactant property, namely cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, n -octylamine, tetrapropylammonium bromide (TPABr) and these amines give good yield except TPABr. Attempts with other amines without surfactant properties, such as n -propylamine, diethylamine, triethylamine, triethanolamine templates did not give any precipitate in the present reaction scheme. The above synthesis followed by sonication did not change the trend. However addition of dodeycl sodium sulfate surfactant before sonication gave precipitate in all amines, which shows particle growth is induced by surfactant.

A retrospective audit of Novagold™ ‘hydrogel’ breast implants

Novagold breast implants were withdrawn from use in the UK in December 2000 due to concerns about the metabolic fate of the implant filler material, the hydrogels polyvinylpyrrolidine (PVP) and guar gum. A total of 250 women in the UK had these implants, 66 of which were performed in our unit. A total of 44% of cases needed further surgery for complications. Capsular contracture requiring surgical intervention occurred in 32%. Symptomatic ruptures occurred in 10.5%. Infection was recorded in 1.5%. From comparison with published data, the incidence of capsular contracture is comparable, but the occurrence of rupture is almost twice that of saline-filled implants. It is hypothesised that an osmotic gradient occurs due to the hydrogel filler causing the implants to swell and weaken the elastomer shell. When the PVP/guar gum filler is released into the subcutis, a vigorous tissue reaction occurs causing pain and swelling. These results show that this composition of implant poses potential risks, which should be considered by manufacturers in the future. We advise removal of symptomatic implants, as rupture is likely to have occurred.

Synthesis of silica hollow nanosphere using poly vinyl alcohol

Silica hollow microsphere was synthesized in presence of poly vinyl alcohol. Effect of a UV absorber, say 2,2',4,4'-tetrahydroxy benzophenone on particle growth was studied. Increase in amount of the UV absorber results in fibrous material. Same way effect of other polymers such as polyvinyl pyrrolidine and polyethylene glycol were also studied. They also give fibrous material.

Function of additives in electrolytic preparation of copper powder

This work investigates the function of additives in the electrolytic preparation of copper powder under various conditions: without additive, with traditional additive, or with polyvinylpyrrolidine (PVP) and sodium polyoxyethylene alkylphenol sulfonate (APES) additives. The influences of the additive on the composition and particle size distribution of copper powder as well as on the current efficiency are also studied. The results show that the particle size distribution of copper powder cannot be reduced without additive or with traditional additive, but the mixture of PVP and APES is an ideal additive because it can make the copper powder particle size distribution reach the level of practical demand and widen the particle size distribution range.

Buccoadhesive drug delivery system of isosorbide dinitrate: Formulation and evaluation

Buccoadhesive buccal delivery systems for isosorbide dinitrate in the form of unidirectional buccal films were developed and characterized for improving bioavailability. The films were formulated by solvent casting method using different bioadhesive polymers like Carbopol 934P and polyvinyl pyrrolidone by using two different plasticizers propylene glycol and diethyl phthalate. Unidirectional release was achieved by preparing composite films with backing membrane. The films were characterized on the basis of their physical characteristics, bioadhesive performance, and other parameters. In vitro studies revealed that release rate of isosorbide dinitrate was higher from carbopol films containing ratio of Eudragit RL100 and polyvinyl pyrrolidine in proportion of 1:2 and 2:1, respectively by using both plasticizers. Drug diffusion from buccal films showed apparently zero order kinetics and release mechanism was diffusion controlled after considerable swelling. All the films exhibited sufficient in vitro bioadhesion strength. Promising formulations were further studied for temperature dependent stability studies. Results of our preliminary experiments indicate that, therapeutic level of isosorbide dinitrate can be achieved using this buccaladhesive formulation.

Temperature-sensitive Mutant of the Caenorhabditis elegans Neurotoxic MEC-4(d) DEG/ENaC Channel Identifies a Site Required for Trafficking or Surface Maintenance

DEG/ENaC channel subunits are two transmembrane domain proteins that assemble into heteromeric complexes to perform diverse biological functions that include sensory perception, electrolyte balance, and synaptic plasticity. Hyperactivation of neuronally expressed DEG/ENaCs that conduct both Na+ and Ca2+, however, can potently induce necrotic neuronal death in vivo. For example, Caenorhabditis elegans DEG/ENaC MEC-4 comprises the core subunit of a touch-transducing ion channel critical for mechanosensation that when hyperactivated by a mec-4(d) mutation induces necrosis of the sensory neurons in which it is expressed. Thus, studies of the MEC-4 channel have provided insight into both normal channel biology and neurotoxicity mechanisms. Here we report on intragenic mec-4 mutations identified in a screen for suppressors of mec-4(d)-induced necrosis, with a focus on detailed characterization of allele bz2 that has the distinctive phenotype of inducing dramatic neuronal swelling without being fully penetrant for toxicity. The bz2 mutation encodes substitution A745T, which is situated in the intracellular C-terminal domain of MEC-4. We show that this substitution renders both MEC-4 and MEC-4(d) activity strongly temperature sensitive. In addition, we show that both in Xenopus oocytes and in vivo, substitution A745T disrupts channel trafficking or maintenance of the MEC-4 subunit at the cell surface. This is the first demonstration of a C-terminal domain that affects trafficking of a neuronally expressed DEG/ENaC. Moreover, this study reveals that neuronal swelling occurs prior to commitment to necrotic death and defines a powerful new tool for inducible necrosis initiation.

Do all tannins have similar nutritional effects? A comparison of three Brazilian fodder legumes

Three tropical legumes, namely Leucaena leucocephala, Sesbania sesban and Cajanus cajan, were subjected to chemical analysis plus in vitro, in situ and in vivo evaluations. Three different assays were used to determine total tannins: adsorption to polyvinyl pyrrolidine (PVPP-tannins), radial diffusion (RD-tannins) and protein precipitation capacity (BSA-tannins). Total phenols, total tannins and condensed tannins were highest for Sesbania. RD-tannins were correlated with total phenols ( r 2 = 0.93), PVPP-tannins ( r 2 = 0.92) and condensed tannins ( r 2 = 0.99). The protein precipitation capacity of Sesbania, Leucaena and Cajanus were 25.9, 6.13 and 4.05 μg BSA/g DM, respectively. Gas production at 24 h was negatively correlated with total phenols ( r 2 = 0.99), PVPP-tannins ( r 2 = 0.99) and condensed tannins ( r 2 = 0.91). The RD-, PVPP-tannins and the response to polyethylene glycol (PEG) in the gas production assay appeared to be useful as a first screen for tannins. In situ degradability did not reflect any adverse effects of tannins. However, in vivo experiments showed that the apparent DM digestibility of Sesbania and Leucaena was lower than the basal diet. The apparent protein digestibility was lower for all legumes compared to the basal diet. Most treatments caused a negative nitrogen balance. The problems associated with browse feeding were not only related to tannin contents, other factors such as inherently poor digestibility and low energy intake may also have lead to the poor animal performance on these diets. We propose, given the limitations of current tannin assays, that it is not possible to predict beneficial or harmful nutritional effects from total tannin concentrations per se.

Fertile and developmental life of human and mouse sperm after immobilization in PVP using a mouse ICSI model.

Objective: The use of intracytoplasmic sperm injection (ICSI) in the treatment of severe male factor infertility generally utilizes live sperm which are immobilized just prior to injection. In some cases of freshly obtained or post-thawed samples, only immotile sperm are available. There are few systematic observation on the fertile or developmental life of immotile sperm. Using a mouse ICSI system, the objective of this study was to examine how increasing time intervals after sperm immobilization in PVP affected egg activation and embryo development to the blastocyst stage. Design: In vitro controlled trial. Materials/Methods: Human sperm were obtained from semen samples of volunteers. Swim-up sperm were prepared in HEPES-CZB media and added to 10% polyvinylpyrrolidine (PVP). Using brief piezo pulses, individual sperm were immobilized and either used immediately for ICSI (T = 0 hrs) or maintained for intervals between 1 and 24 hours before injection into freshly prepared superovulated B6D2F1 mouse eggs. Egg activation was scored 6–8 hours later as the formation of two pronuclei. Epididymal mouse sperm were suspended in 10% PVP and heads separated from tails using a brief piezo pulse. At intervals from 1 to 24 hours after separation, heads were injected into mouse eggs. Activation at 6–8 hours post-injection as well as daily development to 120 hours was scored. The effect of storing mouse sperm heads in a “nucleus isolation medium” (NIM) containing a high potassium concentration was also evaluated after injection at similar time intervals. Results: For human sperm, increasing intervals up to 24 hrs had no significant effect on their ability to activate mouse eggs (0 hrs = 94%; 24 hrs = 89%; p < 0.05). In mouse sperm experiments, a statistically significant effect on activation could be seen at 6 hrs, although activation occurs in the majority of eggs even at 24 hours (0 hrs = 98%; 4 hrs = 92%; 6 hrs = 79% (p < 0.005); 24 hrs = 82%). Embryogenesis was more sensitive; a negative effect on development to the blastocyst stage was detected just 1 hour after sperm immobilization, and this progressively worsened with time (0 hrs = 75%; 1 hr = 39% (p < 0.005); 2 hrs = 37%; 3 hrs = 26%; 4 hrs = 8%; 6 hrs = 0%; 24 hrs = 0%). Mouse sperm head maintenance in NIM offered some developmental protection over a 1–2 hour time interval only (0 hrs = 78%; 1 hr = 72%; 2 hrs = 65%; 3 hrs = 31%; 4 hrs = 5%; 6 hrs = 3%; 24 hrs = 3%). Conclusions: Egg activation factor (s) leading to pronucleus formation in both human and mouse sperm are relatively stable over a 24 hour time period after membrane disruption using piezo immobilization. However, developmental damage occurs within 1-2 hours in the mouse system, delayed by manipulating the potassium concentration. Clinically, this underscores the limitations of using fertilization rates in assessing ICSI, and suggests that using immotile sperm without evaluating membrane integrity poses developmental risks. Finally, human sperm should be utilized for ICSI as soon as possible after immobilization. Supported by: Research was supported by the Pacific IVF Institute.

Procedure for the partial purification of apple leaf polyphenol oxidase suitable for commercial application

A method suitable for commercial application was developed for the partial purification of apple polyphenol oxidase (aPPO) from apple ( Malus pumila L Bramley’s Seedling). The yield of aPPO extracted from leaf tissue was greater than that from fruit. The aPPO was extracted from apple leaf tissue in a phosphate buffer at pH 7 (20 m m) containing 5.0 ml l −1 Triton X-100 and 2.5 g l −1 polyvinylpyrrolidine (PVP). The extract was clarified by centrifugation or by standing for a period of 2 weeks. The aPPO was subsequently purified 50-fold by the sequential use of DEAE-Sephadex and ultrafiltration. The DEAE-Sephadex was applied as a preswollen batch with its use optimized for recovered specific activity of aPPO and cost. Using phloridzin and 4-methyl catechol as substrates, the partially purified aPPO had specific activities of 0.089 and 4.9 μkat mg −1, respectively, and K m values of 0.6 and 3.6 m m, respectively. Recovery of phloridzin hydroxylase activity relative to DEAE-Sephadex was 3.3 μkat g −1 and relative to apple leaf tissue (following purification) was 8.0 nkat g −1.

Effect of ethanol composition in water coagulation bath on morphology of PVDF hollow fibre membranes

Polyvinylidene fluoride (PVDF) hollow fibre membranes were spun from 20% PVDF (Kynar® k-760) in N,N-dimethylacetamide (DMAc) by a dry-jet-wet spinning technique. Polyvinyl-pyrrolidine (PVP) was used as a pore-forming additive. Effect of coagulation medium, ethanol (10–50%) and water (90–50%), on the morphology of the PVDF hollow fibre membranes was studied using SEM. The gas permeation method was used to estimate the surface pore size and effective surface porosity of the PVDF hollow fibre membrane prepared. An attempt has been made to correlate the effect of composition of ethanol:water coagulation medium on membrane morphology with factors like the solubility parameter and diffusivity of solvent and nonsolvent used in the preparation of the hollow fibre membranes.

Structural and optical characteristics of ZnSe nanocrystals synthesized in the presence of a polymer capping agent

Quantum dots of ZnSe have been precipitated in the presence of polyvinyl pyrrolidine using a modified chemical bath method. Addition of the polymeric capping agent serves to limit particle growth and stabilize nanocrystals. Analysis of X-ray diffraction (XRD) measurements indicates that capped particles attain an average particle diameter of only 15 versus 34 Å for the uncapped material. Transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) results show nanocrystals to be single crystals encapsulated in polymeric material, while SAED patterns confirm that the cubic phase of ZnSe was obtained with this synthesis route. Observation of a blue shift in the optical absorption and luminescence data is consistent with the reported reduction in nanocrystal size below the ZnSe bulk exciton Bohr diameter of ∼90 Å.

The Effect of Polyvinylpyrrolidine on the Stability of Taurolidine

ABSTRACTIn an aqueous solution, taurolidine reversibly degrades to taurultam, hydroxymethyltaurultam, taurineamide, and formaldehyde. The objectives of this research were to investigate the mechanism of polyvinylpyrrolidine (PVP)-induced taurolidine stabilization by measuring the effect of PVP on the rate and extent of formaldehyde release from taurolidine and its decomposition products, the ionization of taurineamide, and the NMR and FT-IR spectra of taurineamide. PVP was found to a) increase the rate constant for taurultam formation from taurineamide and formaldehyde, b) decrease the apparent pKa of taurineamide, and c) alter the NMR and FT-IR taurineamide spectra. The effect of PVP on the stability of taurolidine was to increase the stability of its primary degradation product, taurultam, which, in turn increased taurolidine stability because taurultam was reversibly formed from taurolidine. Furthermore, the increased stability of taurultam in acidic, aqueous PVP solutions was due to an increased rate of taurultam formation from its primary degradation products: taurineamide and formaldehyde. The rate constant for taurultam formation increased threefold in the presence of 5% PVP. The rate increase was caused by the interaction of unprotonated taurineamide with PVP. The estimated taurineamide-PVP association constant was 1800 M-1. This interaction decreased the concentration of unreactive/protonated taurineamide while increasing the concentration of unprotonated/associated substrate which was found to be fivefold less reactive than the free/unprotonated amine.

Differential binding of Pseudomonas aeruginosa to normal and cystic fibrosis tracheobronchial mucins.

Pseudomonas aeruginosa infection is a leading cause of deterioration of pulmonary function in patients with cystic fibrosis (CF). The interaction of the bacterium with CF and non-CF tracheobronchial mucins was examined to understand the biochemical basis for the high susceptibility of the lungs of CF patients to infection by P.aeruginosa. The binding of radiolabelled bacteria to pure mucins in solid-phase assays was not significantly above non-specific binding to various blocking agents, such as bovine serum albumin, Tween 20, milk powder and polyvinyl pyrrolidine. Further, there was a tendency for the bacteria to be excluded from plastic wells and membranes coated with mucin. Therefore, an indirect approach involving the binding of radiolabelled P.aeruginosa to asialo GM1 ganglioside, the putative receptor for the bacteria on tracheal cells, was used to compare the interaction of CF and non-CF mucins with the bacteria. Highly purified preparations of CF mucin were consistently better inhibitors of the binding of the bacteria to asialo GM1 ganglioside than non-CF mucin preparations. In the case of the binding of a stable mucoid strain, the difference was statistically significant (P < 0.001) at all concentrations of mucin tested. For the non-mucoid strain, the difference was significant only at the higher concentrations. Of the saccharides tested similarly, sialyl lactose and the oligosaccharide portion of asialo GM1 were found to be good inhibitors. The increased binding of the bacteria to CF mucin was further confirmed by a solution binding assay in which the binding of 125I-labelled mucin to unlabelled bacteria was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Markers for faecal fat estimation in monitoring steatorrhoea in cystic fibrosis.

Polyethylene glycol (PEG) 4000 is one of numerous substances used as non-absorbable markers to correct for variable faecal output when assessing daily faecal losses of nutrients. The introduction of enteric coated micro-encapsulated pancreatic enzyme (EMPE) preparations has greatly improved the control of fat malabsorption in cystic fibrosis and chronic pancreatitis patients. Unfortunately, these enzyme preparations contain significant quantities of PEG 4000 or polyvinyl pyrrolidine (PVP) as components of the enteric coating and thus PEG 4000 cannot be used either as a faecal marker, or in intubation studies, if these enzyme preparations are being used.

Ontogeny of B cells in CBA/N mice. Evidence for a stage of responsiveness to thymus-independent antigens during development.

This paper deals with the CBA/N mice, a strain bearing a genetic defect in their B-cell compartment. By using a previously described system we have been able to show that the immature cells of CBA/N mice are functionally indistinguishable from normal immature cells, in that both can be triggered to respond to thymus-independent (TI) antigens, provided they are supplied with helper T cells. When the maturation is completed, CBA/N B cells are unable to respond to TI antigens (like lipopolysaccharide and polyvinyl pyrrolidine) irrespective of the presence of helper T cells, whereas normal mature B cells have grown able to respond without any help. These data allow us to reject the hypothesis that CBA/N mice are arrested at an immature stage and clearly support the idea that they have deviated during development so that only thymus-dependent B cells develop.

Soluble Polyvinylpyrrolidine and Bovine Serum Albumin Adsorb Polyphenols from Soybean Suspension Cultures

Soybean (Glycine max [L.] Merrill, cv. Dare) suspension cultures grown in Gamborg B5 medium became discolored and the cells began aggregating after 1 week in culture, especially in the absence of 2,4-dichlorophenoxyacetic acid (2,4-D). The addition of either soluble polyvinylpyrrolidine (PVP) or bovine serum albumin (BSA) to cultures grown in Gamborg B5 medium with 2,4-D prevents discoloration and cell aggregation by adsorbing excess polyphenols from the cells. Transfer of the PVP-treated cultures to fresh medium without 2,4-D stimulated the recurrence of excess polyphenols. Cultures pretreated with BSA did not develop excess polyphenols when transferred to fresh 2,4-D-free medium. Addition of either PVP or BSA to cultures grown in the absence of 2,4-D was found to inhibit growth.

Hormonal requirements for the maintenance of luteal function in hypophysectomized, pseudopregnant rats.

SUMMARY Pseudopregnant rats with traumatized uteri were hypophysectomized on day 6 and injected with various hormones over the next 4 days. Luteal function was assessed on day 10 of pseudopregnancy by weighing deciduomata and determining luteal and plasma levels of progesterone by a competitive protein-binding assay. Daily treatment with 0·25 mg prolactin restored plasma and luteal levels to the values of intact pseudopregnant animals; however, the deciduomata weighed only 55% of control values. Combining oestrone with prolactin restored deciduomata weight to control values without affecting peripheral progesterone levels. Either 200 μg of follicle-stimulating hormone (FSH) or 5 μg luteinizing hormone (LH) could be substituted for oestrone, in conjunction with prolactin, to increase deciduomata weight to control values. Moreover, the combination of prolactin with FSH or LH significantly increased peripheral plasma levels of progesterone beyond the effects of prolactin alone. Higher doses of LH were luteolytic as shown by decreased deciduomata weight and considerable variation in plasma and luteal values of progesterone. LH given alone — either in saline or polyvinyl pyrrolidine — failed to maintain any of the parameters of luteal activity mentioned above. The results reaffirm the primacy of prolactin in vivo as the principal luteotrophic hormone of the rat and indicate that selected doses of LH or FSH play an additive role in further increasing peripheral levels of progesterone.

Drinking and urine production in the European eel ( Anguilla anguilla L.)

The drinking rates of freshwater and seawater adapted eels at different temperatures were measured using polyvinyl pyrrolidine- 131I. Concomitantly the urine production of freshwater eels was also measured. Freshwater eels acclimatized at 8°C had lower rates of drinking and urine production than those at 12° and higher figures were given by those at 23°. Unacclimatized eels at 23° gave the highest figures. Hypophysectomy was followed by reduced drinking rates and urine output and adrenalectomy gave the latter effect. Seawater cels at 12° had drinking rates about 6.5 times higher than those for freshwater eels at the same temperature. Hypophysectomy had no clear-cut effects.