Presence Of Methylcellulose Research Articles

Spectrophotometric determination of gliclazide in pharmaceuticals and biological fluids through ternary complex formation with eosin and palladium (II)

A simple and sensitive spectrophotometric method has been developed for the determination of gliclazide (GLZ) in pharmaceutical formulations and biological fluids. The proposed method is based upon the formation of a ternary complex between palladium (II), eosin and GLZ in the presence of methyl cellulose as a surfactant and acetate buffer of pH 4.5. The ternary complex showed an absorption maximum at 550 nm. The solution of ternary complex obeyed Beer’s law over the concentration range of 0.5–4 μg ml –1 with minimum detectability (S/N = 2) of 0.05 μg ml –1 (1.545 × 10 –7 M). The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using the official or reference spectrophotometric method. The proposed method was further applied to spiked human urine and plasma, the percentage recoveries were 97.84 ± 0.72 and 97.43 ± 0.83, respectively, ( n = 4). A proposal of the reaction pathway was presented.

Selective flotation separation of plastics by chemical conditioning with methyl cellulose

The floatability of seven plastics (POM, PVC, PET, PMMA, PC, PS and ABS) in the presence of methyl cellulose (MC) and separation of plastics mixtures were investigated in this paper. It was found that the seven plastics can be separated into three groups by using the wetting agent MC. Group one includes POM and PVC. They are depressed at very low MC concentrations. Group two, including PET, PMMA and PC, has an intermediate floatability. Group three (ABS and PS) has a high floatability. They are almost not depressed within the given MC concentration range. In order to understand the mechanism of selective flotation of plastics and the chemical conditioning process, surface chemical factors, such as wettability of plastics and surface tension of flotation medium, and gravity factors, such as particle density and shape, were studied. It was found that the depressing effect of MC on plastics is ascribed mainly to its adsorption on the plastics surfaces. The MC molecules absorbed on plastics expose some of their polar groups oriented towards the aqueous phase, hence making the plastics surfaces hydrophilic. In addition, flotation selectivity for the plastics is dominated not only by wettability of plastics, but also by particle size, density and shape.

Phalloidin affects the myosin-dependent sliding velocities of actin filaments in a bound-divalent cation dependent manner.

We examined sliding velocities in vitro of four types of actin filaments, that is, filaments with Ca2+ or Mg2+ bound at the high affinity metal binding site, each with rhodamine phalloidin bound with a high or low stoichiometry. When surfaces coated with a high density of heavy meromyosin (HMM) were used, high stoichiometric concentrations of rhodamine phalloidin reduced sliding velocities of only Ca2+-actin filaments, by 40%. As the HMM density on surfaces was reduced, continuous movement of actin filaments became dependent on the presence of methylcellulose and sliding velocities of all four types became progressively slower. Interestingly, Ca2+-actin filaments with a high stoichiometric concentration of rhodamine phalloidin were the fastest among the four types of filaments on sparse HMM surfaces. In contrast, phalloidin did not affect steady state ATPase activities of HMM in the presence of Ca2+- or Mg2+-actin filaments. We speculate that the reversal of the order of sliding velocities among the four types of actin filaments between high and low densities of HMM relates with different axial elasticity of the actin filaments, so that stiffer filaments move slower on dense HMM surfaces, but faster on sparse surfaces, than elastic ones.

Spectrophotometric Determination of Chlorprothixene with Eriochrome Cyanine R

Two spectrophotometric methods are described for the determination of chlorprothixene (CPT). The first method is based on the extraction of the ion-association compound of CPT with eriochrome cyanine R (ECR) into butanol. The extracted compound in the organic solvent obeys Beer’s law in the range 5–80 μg mL −1. The second method is based on the measuring of the absorbance of the aqueous solution of the compound of CPT with ECR in presence of methylcellulose. Conformity with Beer’s law was evident in the range 0.7–10 μg mL −1 of chlorprothixene. The methods were applied for the determination of chlorprothixene contents in pharmaceuticals.

Drosophila ACT88F indirect flight muscle-specific actin is not N-terminally acetylated: a mutation in N-terminal processing affects actin function

Many eukaryotic proteins are co and post-translationally modified at their N termini by removal of one or two amino acid residues and N α-acetylation. Actins show two different forms of N-terminal processing dependent on their N-terminal sequence. In class II actins, which include muscle actins, the common primary sequence of Met-Cys-Asp-actin is processed to acetyl-Asp-actin. The functional significance of this in vivo is unknown. We have studied the indirect flight muscle-specific actin, ACT88F, of Drosophila melanogaster. Our results show that ACT88F is N-terminally processed in vivo as a class II actin by removal of the first two amino acid residues (Met and Cys), but that uniquely the N terminus is not acetylated. In addition we show that ACT88F is methylated, probably at His73. Flies carrying the mod − mutation fail to complete post-translational processing of ACT88F. We propose that the mod gene product is normally responsible for removing N-acetyl-cysteine from actin. The biological significance of this process is demonstrated by observations that retention of the N-acetyl-cysteine in ACT88F affects the flight muscle function of mod − flies. This suggests that the extreme N terminus affects actomyosin interactions in vivo, a proposal we have examined by in vitro motility assays of ACT88F F-actin from mod − flies. The mod − actin only moves in the presence of methylcellulose, a viscosity-enhancing agent, where it moves at velocities slightly, but significantly, reduced compared to wild-type. These data confirm that N-acetyl-cysteine at the N terminus affects actomyosin interactions, probably by reducing formation of the initial actomyosin collision complex, a process known to involve the actin N terminus.

Effect of methylcellulose on the stability of oil-in-water emulsions: influence of the disperse phase

The influence of nature of the disperse phase on the stability of oil-in-water emulsions containing nonionic emulsifiers and methylcellulose 4000 as an auxiliary emulsifier was investigated. One stable and three unstable base emulsions each of olive oil and of mineral oil were formulated with an emulsifier blend of Tween® and Span®. The stable emulsion (SE) contained 2% emulsifier blend optimized for maximum stability. Three unstable emulsions were formulated from the SE formulation: one with 0.5% emulsifier blend as of the SE formulation (UE1), one with excessive hydrophilic emulsifier (UE2) and one with excessive lipophilic emulsifier (UE3). A series of emulsions was prepared containing increasing amounts of methylcellulose 4000 for each base emulsion. The particle size of all olive oil emulsions was reduced (UE2>SE>UE3) and the viscosity was increased (UE2>SE>UE3) on addition of methylcellulose. The stability of these emulsions improved in the presence of methylcellulose. However, the addition of the polymer caused instability in mineral oil emulsions containing lower concentrations of the hydrophilic emulsifier (Tween®). These results suggest that: (i) methylcellulose and the hydrophilic emulsifier associate to form a complex; (ii) this complex when present at the mineral oil-water interface would be dislodged from the interface due to less interaction between the non-polar oil and the polyoxyethylene (POE) chain of the hydrophilic emulsifier; and (iii) this complex when present at the olive oil-water interface would stabilize emulsions due to higher interaction between the polar oil and the POE chain of the hydrophilic emulsifier.

Spectrophotometric and spectrofluorimetric estimation of ciprofloxacin and norfloxacin by ternary complex formation with eosin and palladium(II)

Spectrophotometric and spectrofluorimetric methods for the determination of two broad-spectrum fluoroquinolone antibacterials (ciprofloxacin and norfloxacin), either in pure form or in tablets, are described. Both methods are based on the formation of a ternary complex between palladium(II), eosin and the fluoroquinolone in the presence of methyl cellulose, as surfactant. Spectrophotometrically, under the optimum conditions, the ternary complexes showed an absorption maximum at 545 nm, with apparent molar absorptivities of 3.4 × 10 4 and 2.7 × 10 4 l mol −1 cm −1 and Sandell's sensitivities of 1.01 × 10 −2 and 1.12 × 10 −2 μg cm −2 for ciprofloxacin and norfloxacin, respectively. The solution of the ternary complex obeyed Beer's law in the concentration range 3–10 μg ml −1 for both quinolones. The proposed method was applied to the determination of the two drugs in pharmaceutical tablets. A fluorescence quenching method for the determination of both quinolones by forming this ternary complex was also investigated for the purpose of enhancing the sensitivity of the determination. The results obtained by the application of both procedures and the USP XXIII methods were in good agreement and statistical comparison by means of Student's t-test and the variance ratio F-test showed no significant differences between the three methods.

Adaptation of insect cells to suspension culture

An assessment was made of the effects of successive passages, the concentration of fetal calf serum, and the presence of methyl cellulose and pluronic F-68 on the adaptation of Spodoptera frugiperda and Trichoplusia ni cells from stationary to suspension growth in shake flasks and an external loop airlift bioreactor. The studies showed that it takes about six successive passages to adapt Spodoptera frugiperda cells to suspension growth in shake flasks. The population doubling time was about 35 h with a maximum cell density of 5 × 10 6 cells/ml. In comparison, pour cell growth was observed for Trichoplusia ni cells in shake flasks. The presence of a higher serum concentration, methyl cellulose, and pluronic, while beneficial for cell growth, was not as important as the passage number. Preliminary experiments with an external loop airlift bioreactor suggest that Spodoptera frugiperda insect cells, previously adapted to shake-flasks, cannot survive air-sparging if the bubble diameter is less than 500 μm.

Effect of microcrystalline cellulose and cross-linked sodium carboxymethylcellulose on the properties of tablets with methylcellulose as a binder

The action of microcrystalline cellulose and cross-linked sodium carboxymethylcellulose on the water penetration, disintegration and dissolution of tablets containing methylcellulose of varying viscosity as a binder was studied. Microcrystalline cellulose was found to have a limited capability to act as a disintegrant in the presence of methylcellulose. The disintegration time was long, the dissolution was slow and the water uptake was low for these tablets, whereas cross-linked sodium carboxymethylcellulose improved these tablet properties by its marked capacity to absorb water, swell and thereby overcome the binding and adhesive effect of and blocking of tablet pores by methylcellulose. These tablets, with higher viscosity grades of methylcellulose disintegrated into large fragments. As a result, they had a lower disintegration time and a higher water uptake.

The Sensitivity to Cytosine Arabinoside of the Blast Progenitors of Acute Myeloblastic Leukemia

Two culture methods are available for the study of the blast cells of acute myeloblastic leukemia (AMD. One is an assay for clonogenic precursors; it depends on their ability to form blast colonies in culture in the presence of methyl-cellulose and suitable growth factors. The other assesses the growth of blast cells in suspension culture, where growth is measured by increasing numbers of clonogenic cells. We have compared the two methods as assays for the cytotoxic effects of the chemotherapeutic drug cytosine arabinoside (Ara-C). Marked patient-to-patient variation was found using either method; however, the slopes of the dose-response curves were usually greater when cells were exposed to drug in suspension rather than in methyl-cellulose. Control experiments showed that the difference could not be explained by drug carry-over from the suspension cultures to the methylcellulose plates when clonogenic cells in the suspensions were assessed. Further, the survival curves for Adriamycin were very similar, regardless of which assay was used. No correlation was found between D10 Ara-C values measured in suspension or in methylcellulose. However, a significant association with outcome was found between D10 Ara-C in suspension and response to treatment with a regimen in which Ara-C was the only chemotherapeutic agent used. No such association was detected when the D10 values obtained with the clonogenic assay were compared with outcome for the same group of 15 patients. Finally, a feasibility experiment was performed in which blast cells were exposed to Ara-C repeatedly during exponential growth over 238 days. A dose-related inhibition of growth was observed; no evidence was seen of emerging drug-resistant cells. Nor did the morphology of the cells change as a result of drug exposure. We conclude that drug sensitivities of AML blast cells in culture are dependent on measurement methods, even when techniques affecting cell proliferation are compared. Measurements of drug sensitivity in culture may best be interpreted when the bases of the assay systems are understood.

The sensitivity to cytosine arabinoside of the blast progenitors of acute myeloblastic leukemia

Two culture methods are available for the study of the blast cells of acute myeloblastic leukemia (AML). One is an assay for clonogenic precursors; it depends on their ability to form blast colonies in culture in the presence of methylcellulose and suitable growth factors. The other assesses the growth of blast cells in suspension culture, where growth is measured by increasing numbers of clonogenic cells. We have compared the two methods as assays for the cytotoxic effects of the chemotherapeutic drug cytosine arabinoside (Ara-C). Marked patient- to-patient variation was found using either method; however, the slopes of the dose-response curves were usually greater when cells were exposed to drug in suspension rather than in methylcellulose. Control experiments showed that the difference could not be explained by drug carry-over from the suspension cultures to the methylcellulose plates when clonogenic cells in the suspensions were assessed. Further, the survival curves for Adriamycin were very similar, regardless of which assay was used. No correlation was found between D10 Ara-C values measured in suspension or in methylcellulose. However, a significant association with outcome was found between D10 Ara-C in suspension and response to treatment with a regimen in which Ara-C was the only chemotherapeutic agent used. No such association was detected when the D10 values obtained with the clonogenic assay were compared with outcome for the same group of 15 patients. Finally, a feasibility experiment was performed in which blast cells were exposed to Ara-C repeatedly during exponential growth over 238 days. A dose-related inhibition of growth was observed; no evidence was seen of emerging drug-resistant cells. Nor did the morphology of the cells change as a result of drug exposure. We conclude that drug sensitivities of AML blast cells in culture are dependent on measurement methods, even when techniques affecting cell proliferation are compared. Measurements of drug sensitivity in culture may best be interpreted when the bases of the assay systems are understood.

The Effect of Different Agars, Agaroses and Methyl Cellulose on the in Vitro Proliferation of a Human Urinary Transitional Cell Carcinoma Cell Line

The effects of different agars (Bacto-agar and deoxycholate lactose agar), agaroses (LE, ME, Sea Plaque and Sea Prep 15/45) and methyl cellulose on the growth of a human tumor cell line, derived from a transitional cell carcinoma of the urinary bladder, were examined. The overall growth in the presence of agars and agarose was generally less than in liquid medium alone. In contrast, growth in the presence of methyl cellulose was significantly enhanced. Thus, methyl cellulose may be a useful agent for optimizing the proliferation of primary tissue cultures prepared from human transitional cell carcinomas.

Effects of viscosity on phototactic movement and period of cell rotation in Cryptomonas sp.

The swimming speed, the period of cell rotation, and the critical dark period between intermittent light pulses in the positive phototactic response of Cryptomonas sp. strain IAM CR–1 were measured in the presence of methyl cellulose, which slows down the cell movement by raising the viscosity of the medium. The cell rotated once while it swam one pitch of the helical path, irrespective of the rotational period. The period of helical movement (the rotational period) was 0.65 s and 0.45 s in the presence and absence of 4.5 g/liter methyl cellulose, respectively. The phototactic response to repeated pulses of light could no longer be induced when the dark interval exceeded 0.33 s in medium with 4.5 g/liter methyl cellulose and 0.23 s in medium without it. The ratio of the critical dark period between repeated light pulses to the rotational period was always about 0.5, although the rotational period was lengthened 1.4 times with methyl cellulose. Thus, the present results clearly demonstrated that it is this ratio which is crucial for phototaxis, rather than the absolute length of the critical dark period.

Solubilization of amobarbital by mechanical treatment in the presence of diluents.

Amobarbital was ball-milled, triturated, mortar-ground or stamp-milled in the absence or in the presence of various kinds of diluents, and the variation of solubility of amobarbital from these samples in the KH2PO4-Na2HPO4 buffer solution of pH of 6.0 at 30°was investigated. It was suggested from the results of the elemental analysis, measurement of the mass spectra and the infrared spectra, and the chemical analysis by thin-layer chromatography and gas chromatography that amobarbital in the mechanically treated mixtures of precipitated silica or carbon black was hydrolyzed by the addition of water. It was also suggested that amobarbital decomposed or formed complex by ball-milling in the presence of potato starch. But, it was considered that decomposition of amobarbital by the mechanical treatment in the absence and in the presence of the other diluents was negligible. Solubility of amobarbital in the buffer solution increased by mechanical treatment in the presence of methyl cellulose or hydroxypropyl cellulose. It was considered that solubilization of amobarbital was related to the decrease in the intensity of the signals of amobarbital in the X-ray diffraction diagrams and dropping of the melting point of amobarbital by mechanical treatment in the presence of the diluent. It was also considered that solubilization of amobarbital was due to the interaction with the diluent in the suspension caused by mechanical treatment and to the kind of the crystal structure of amobarbital formed by recrystalization after dissolution.

Methylcellulose effect on cell proliferation and glucose utilization in chemically defined medium in large stationary cultures.

AbstractThree different established strains of mammalian cells were grown in chemically defined medium in large cultures. The degree of proliferation of cells of an established strain from human skin in large stationary cultures was significantly greater in the presence of methylcellulose (medium NCTC 135M) than in its absence (medium NCTC 135). The relatively fragile cells of a derivative of monkey kidney LLCMK2 strain were carried in large stationary cultures through 11 transfer generations during 152 days. The presence of methylcellulose was associated with higher cell population levels, proliferation rates, and cell viability. Cells of this strain utilized glucose at an extremely high rate; during two representative periods the rate averaged 1.2 mg/106 cells/day in cultures on medium 135M and 1.9 mg in medium 135.In a 53‐day experiment with mouse fibroblast 2071‐L cells, the cells in suspension culture during the first 28 days went through the normal lag, logarithmic plateau, and initial decline phases in medium 135M, and then were transferred to large stationary cultures, where they proliferated for 7 days at uniformly high rates in both medium 135 and medium 135M. It appeared that cells of strain 2071‐L in such stationary cultures had no need for Methocel as a protective agent. Glucose utilization rates while these cells were carried in large stationary cultures averaged 2–4 times the rates while they were in suspension cultures: about 0.8 and 0.2 mg/106 cells/day, repectively.