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At least 361 records · Page 20Linked to original sources
PubMed1991

A novel approach to nonradioactive hybridization assay of nucleic acids using stained latex particles.

The paper describes a sensitive latex hybridization assay (LHA) method applied for indirect detection of biotinylated nucleic acid hybrids immobilized on a synthetic membrane. The biotinylated hybrids were visualized by means of latex particles containing the fluorescent dye pyronine G and coated with streptavidin; 1.6 and 0.3 pg of lambda-phage DNA was detected by dot blot hybridizations on nylon membrane and polyethyleneimine-cellophane, respectively. The assay sensitivity was increased by three orders of magnitude over that with fluorescently labeled probes due to encapsulation of the fluorescent dye in polymer particles. LHA is simple (single-stage detection procedure), fast, and more sensitive than any of the other nonradioactive hybridization methods.

Acrolein↗
PubMed1996

Identification of differentially expressed genes induced in pancreatic islet neogenesis.

Cellophane wrapping of the hamster pancreas induces islet neogenesis. We have used the mRNA differential display technique to select for genes expressed during islet neogenesis but not in control pancreata. Ten candidate clones have been identified. Upon sequencing, 6 clones showed a high degree of homology to known genes, 1 showed some, and 3 showed no homology to genes of known sequence. Thus, mRNA differential display is a useful technique to identify genes induced during islet neogenesis, and in combination with screening hamster pancreatic cDNA libraries for full length clones, will enhance the likelihood of capturing the participants in this process.

Animals↗
PubMed1990

Electrofusion of fibroblasts on the porous membrane.

Electric fusion of cells is usually performed in two steps: the first is the creation of tight intercellular contact, the second is an application of electric pulses which induce membrane fusion proper. In the present work a new technique of cell electrofusion on the porous film is described. It consists of preliminary cultivation of cell monolayer on the porous film (protein-coated cellophane). Then cells of the same or any other type are added from above to form a second cell layer upon the first one. The pulses of the electric field are applied normally to the plane of the double cell layer to induce cell fusion. After pulse application a picture of mass polynucleation was observed. At the same time we did not obtain fusion of L cells by means of dielectrophoretic electrofusion technique. This difference in efficiency could be explained by the formation of broad zones of membrane contact between the cells adherent to the film, while during intensive dielectrophoresis only the point contacts were revealed. The high-conducting medium for electric treatment providing an efficient fusion on the film and high cell viability was composed. Neither cytochalasin B nor colcemid affected cell fusion noticeably; however the sodium azide (added with 2-deoxyglucose) inhibited fusion completely. The short hypotonic shock after electric treatment enhanced the rate of polycaryon formation.

Animals↗
PubMed2001

A mechanism of the high frequency AC iontophoresis.

The efficiency and the voltage dependence of the AC iontophoresis were studied in vitro. Two cylindrical glass cells separated by a cellophane film were used, where the donor cell was filled with the solution of target electrolytes and the receptor cell with distilled water. The sinusoidal AC voltage with a frequency of 1 kHz was applied between the two platinum plates located at the opposite ends of two cells. The time variation of the ion concentration was evaluated by measuring the impedance of the solution in the receptor cell. The transportation velocity of the ions increased with the amplitude of the voltage applied between two platinum plate electrodes apart 20 mm up to approximately 15 V, and leveled off above approximately 15 V. A theoretical model is proposed on the AC iontophoresis, where each ion moves together with the surrounding water molecules when it is hydrated. The effective Stokes radius of an ion is assumed to be half of the whole size of the ion with hydrating water molecules. When the external alternating electric field strongly vibrates the ion, the ion-dipole interactions between the ion and water molecules are broken, resulting in the reduced effective Stokes radius, which leads to the increase of the diffusion efficiency.

Algorithms↗
PubMed1999

Cyclodextrins as permeation enhancers: some theoretical evaluations and in vitro testing.

It is well known that cyclodextrins can enhance the permeation of poorly soluble drugs through biological membranes. However, the permeability will decrease if cyclodextrin is added in excess of the concentration needed to solvate the drug. The mechanism of cyclodextrin effect on drug permeability has not been fully explained. The effect of cyclodextrins can not be explained as solely due to increased solubility of the drug in the aqueous donor phase nor can it be explained by assuming that cyclodextrins act as classical permeation enhancers, i.e. by decreasing the barrier function of the lipophilic membrane. In the present work we have modeled the effect of cyclodextrins in terms of mixed barrier consisting of both diffusion and membrane controlled diffusion, where the diffusion of the drug in the aqueous diffusion layer is significantly slower than in the bulk of the donor. This diffusion model is described by simple mathematical equation where the properties of the system are expressed in terms of two constants P(M)/Kd and M1/2. Data for the permeation of hydrocortisone through hairless mouse skin in the presence of various cyclodextrins, and cyclodextrin polymer mixtures, were fitted to obtain values for these two constants. The rise in flux with increased cyclodextrin complex concentration and fall with excess cyclodextrin was accurately predicted. Data for the permeation of drugs through semi-permeable cellophane membrane could also be fitted to the equation. It was concluded that cyclodextrins act as permeation enhancers carrying the drug through the aqueous barrier, from the bulk solution towards the lipophilic surface of biological membranes, where the drug molecules partition from the complex into the lipophilic membrane.

Animals↗
PubMed1992

Cocaine liberation from body packets in an in vitro model.

STUDY OBJECTIVE: To quantitatively assess cocaine liberation from various body packet materials. DESIGN: 100-milligram cocaine packets (plastic bags with various wrapping techniques, paper, and condoms) were placed in a simulated gastric medium. Samples were also tested in an alkalinized gastric medium, with determination of both cocaine and benzoylecogonine concentrations using high-performance liquid chromatography with ultraviolet detection. RESULTS: Cocaine liberation was greatest in acid medium, with increasing liberation from condom packets to cellophane bags (three wrapping techniques used) to paper packets. The same trend was noted in alkaline medium but with a far lower maximum cocaine concentration accompanied by rapid hydrolysis to its inactive metabolite, benzoylecgonine. CONCLUSION: Cocaine liberation of a known quantity of drug is dependent on the wrapping method and material used; thus, a good history from the "body-stuffer" is essential to predict potential cocaine liberation and toxicity. Rapid hydrolysis of cocaine to its inactive metabolite in an alkaline medium implies a role for gastric alkalinization in the acute management of these patients.

Aluminum Hydroxide↗
PubMed1999

Determination of stability constant of beta-cyclodextrin complexes using the membrane permeation technique and the permeation behavior of drug-competing agent-beta-cyclodextrin ternary systems.

The stability constants (Kc) of beta-cyclodextrin (beta-CyD) complexes with phenacetin and various benzoic acids were determined using the membrane permeation technique using a cellophane membrane permeable for guest molecules which was impermeable for beta-CyD molecules. The permeation rate equations of guests in the presence of beta-CyD in the donor phase were derived and the permeation profiles were analyzed as a function of time to determine the Kc values. The Kc values determined using the membrane permeation technique were in close agreement with those determined by the conventional kinetic method and the solubility method. The membrane permeation technique is of greater advantage than the conventional methods, because in the former method the stability constant can be obtained from only one experimental run by analyzing the permeation data as a function of time. In the latter method, on the other hand, some property changes have to be measured at various CyD concentrations and in turn analyzed as a function of CyD concentration. The permeation profiles of phenacetin of the drug-competing agent-beta-CyD ternary system were estimated by using the stability constants and the experimental curves closely matched the theoretically derived ones.

Algorithms↗
PubMed2003

Carbonate ion-selective electrode with reduced interference from salicylate.

A carbonate ion-selective electrode for determination of total carbon dioxide species such as carbon dioxide, bicarbonate and carbonate with reduced interference from salicylate is described. Derivatives of trifluoroacetophenone were used as neutral carriers for carbonate. A polymer-free liquid carbonate-selective membrane with a cellophane outer membrane was found to give a carbonate-selective electrode with a negligible response to salicylate. The electrical contact was obtained by insertion of a silver/silver chloride electrode directly into the liquid membrane. The electrode does not require any aqueous filling solution and is therefore maintenance-free. The response to carbon dioxide species was found to be highly reproducible with a response time of 1-2 min at total carbon dioxide concentrations in the range from 5 to 50 mM. The lifetime of the electrode was at least 3 months. The electrode is regarded as very promising for clinical analysis of carbon dioxide species in body fluids such as plasma and serum.

Artifacts↗
PubMed2000

Reduced phagocytic activity of polymorphonuclear leukocytes in alpha(1,3) fucosyltransferase VII-deficient mice.

Deficiencies in adhesion molecules or their counter-receptors in humans may have severe consequences as exemplified by leukocyte adhesion deficiency (LAD) I or II syndromes. Because such diseases occur with great rarity, animal models are valuable for studying the role of particular adhesion molecules and their natural ligands in immunity. We studied selected immune parameters and general health in mice with a defect in the sialyl-Lewis X antigen (selectin ligand) caused by disruption of the gene encoding alpha(1,3)fucosyltransferase VII (Fuc-TVII). Leukocytes from Fuc-TVII -/- and control mice were tested for adherence to cellophane membranes or polymer particles in vivo and phagocytic activity in vitro. While no difference in adherence was found, the number of neutrophil granulocytes in exudate induced by intraperitoneal injection of polymer beads was reduced in knock-out mice. Moreover, the phagocytic activity in Fuc-TVII -/- mice was significantly reduced. These animals have splenomegaly due to increased hematopoiesis and reduced weight but do not exhibit clinical signs of immunodeficiency. In conclusion, the lack of Fuc-TVII activity leads to several morphological and functional abnormalities without an impact on survival rate.

Animals↗
PubMed1972

On a theory for the passive transport of solute through semipermeable membranes.

It has been shown that thin-film dialysis can be performed in such a way that the limiting rate is the rate of entry of the solute into the membrane from the high-concentration side. The rate of diffusion, therefore, reflects the probability of a molecule entering the pores on the surface and does not depend on the resistance to diffusion offered by the internal structure of the membrane. The good correlation, so generally found, of the order of escape times of given solutes with the order of free diffusion rates is thus explained. The data from stretching experiments with wet cellophane, in which the pore structure is distorted, are also explained.

Biological Transport↗
PubMed2000

Methods to improve the hatchability of checked chicken eggs.

1. The hatchability of checked Leghorn and broiler parent hatching eggs was significantly improved by shell treatment: smearing with synthetic adhesive resin (Fevicol), or pasting cellophane tape or insulation tape over the checked portion of the shell. 2. Shell damage reduced hatchability by increasing evaporative loss, leading to embryonic dehydration. 3. Relative chick weight, expressed as a percentage of egg weight was lower in untreated checked eggs but comparable between intact and shell-treated hatching eggs. 4. The cost of chick production can be reduced by shell treatment of checked hatching eggs, especially in broiler parent eggs.

Animals↗
PubMed1999

Enhanced total peripheral vascular responsiveness in hypertension accords with the amplifier hypothesis.

BACKGROUND: Increases in vascular resistance (or the reciprocal, vascular conductance) in response to constrictor drugs are amplified (or attenuated) in the hindquarter vascular bed of hypertensive rats and rabbits. However, such changes have not been observed for the total peripheral circulation. OBJECTIVE: To assess whether the vascular amplifier applies to the total peripheral circulation in conscious hypertensive rabbits. METHODS: Rabbits were implanted with a flow probe for measuring cardiac output, a left atrial catheter for infusing dilator (adenosine) and constrictor (methoxamine) drugs, and ear artery and vein catheters for measuring mean arterial pressure (MAP) and for giving ganglion blockade. Data from full dose-total peripheral resistance (TPR) or total peripheral conductance (TPC) response curves to adenosine and methoxamine were combined into a logistic function extending from near full dilatation to near maximum constriction. RESULTS: Changes in MAP induced by methoxamine and adenosine were markedly greater in the 'wrap' rabbits (those with renal cellophane wrapping) compared with the sham animals. In the 'wrap' rabbits, the slopes and ranges of the adenosine-TPR response curve and the methoxamine-TPC response curve were 200% and 60%, respectively, of sham values. These data show that TPR changes are amplified, and TPC changes attenuated, to dilator and constrictor stimuli. The relationship between dose-average vascular radius (r; based on Poiseuille's law) over the full range of vascular tone showed that r was narrower in hypertension, but, in contrast to TPR, the degree of narrowing was almost the same between maximum dilatation and constriction. CONCLUSION: The total peripheral circulation in experimental hypertension is a TPR amplifier, or TPC attenuator, in the rabbit, consistent with well-established data in the major vascular beds.

Adenosine↗
PubMed1975

An evaluation of Na+, C1- and pH ion-specific electrodes in the study of the electrolyte contents of epidermal transudate and sweat.

Ion-specific electrode detectors have been used to measure electrolytes in various biological fluids, including sweat. As part of a study of skin barrier function, we have used such electrodes to detect the presence of sodium, chloride and hydrogen (pH) in the transepidermal water loss. This paper describes the effects of cellophane tape stripping (of human forearm epidermis in vivo) on surface electrolyte concentrations, in parallel with observations on transepidermal water loss and galvanic skin resistance.

Adhesiveness↗
PubMed1975

Ribonucleotide reductase from Escherichia coli: demonstration of a highly active form of the enzyme.

Ribonucleotide reductase from Escherichia coli consists of two nonidentical subunits, proteins B1 and B2. The activity of the enzyme in crude extracts prepared from mechanically disrupted bacteria is very low. Enzyme activity is stimulated 5 to 10-fold by addition of an excess of either subunit. Concentrated extracts from cells lysed gently on Cellophane discs (Schaller et al.) contained 10 to 20-fold higher activity than extracts from mechanically disrupted cells. This activity was not further stimulated by either B1 or B2. The system is suitable for complementation tests for the analysis of temperature-sensitive mutants affecting the ribonucleotide reductase system. Concentrated high-speed supernatants from E. coli treated with lysozyme (Wickner et al.) also contained a high ribonucleotide reductase activity, which was stimulated slightly or not at all by addition of B1 and B2. This active form of the enzyme was unstable and could not be purified. The results suggest that the intracellular form of the enzyme consists of a tight complex of proteins B1 and B2, possibly stabilized by other intracellular structures.

Adenosine Triphosphate↗
PubMedDate not supplied

Dialyzer reuse--part II: advantages and disadvantages.

Although single dialyzer use and reuse by chemical reprocessing are both associated with some complications, there is no definitive advantage to either in this respect. Some complications occur mainly at the first use of a dialyzer: a new cellophane or cuprophane membrane may activate the complement system, or a noxious agent may be introduced to the dialyzer during production or generated during storage. These agents may not be completely removed during the routine rinsing procedure. The reuse of dialyzers is associated with environmental contamination, allergic reactions, residual chemical infusion (rebound release), inadequate concentration of disinfectants, and pyrogen reactions. Bleach used during reprocessing causes a progressive increase in dialyzer permeability to larger molecules, including albumin. Reprocessing methods without the use of bleach are associated with progressive decreases in membrane permeability, particularly to larger molecules. Most comparative studies have not shown differences in mortality between centers reusing and those not reusing dialyzers, however, the largest cluster of dialysis-related deaths occurred with single-use dialyzers due to the presence of perfluorohydrocarbon introduced during the manufacturing process and not completely removed during preparation of the dialyzers before the dialysis procedure. The cost savings associated with reuse is substantial, especially with more expensive, high-flux synthetic membrane dialyzers. With reuse, some dialysis centers can afford to utilize more efficient dialyzers that are more expensive; consequently they provide a higher dose of dialysis and reduce mortality. Some studies have shown minimally higher morbidity with chemical reuse, depending on the method. Waste disposal is definitely decreased with the reuse of dialyzers, thus environmental impacts are lessened, particularly if reprocessing is done by heat disinfection. It is safe to predict that dialyzer reuse in dialysis centers will continue because it also saves money for the providers. Saving both time for the patient and money for the provider were the main motivations to design a new machine for daily home hemodialysis. The machine, developed in the 1990s, cleans and heat disinfects the dialyzer and lines in situ so they do not need to be changed for a month. In contrast, reuse of dialyzers in home hemodialysis patients treated with other hemodialysis machines is becoming less popular and is almost extinct.

Anaphylaxis↗
PubMed1983

Influence of hemodialysis on plasma chemotactic activity and the chemotactic responsiveness of polymorphonuclear neutrophils.

Thirty patients with chronic renal failure on maintenance hemodialysis (HD) were studied. Plasma chemotactic activity was estimated using the "under agarose" chemotaxis assay during the first 2 h of HD. It was found that in the fifth minute of HD, patients' plasma became chemotactic, reaching the maximum activity at the tenth minute. The chemotactic activity appearance correlated significantly with the decline in the number of the peripheral neutrophils. Patients' neutrophils, after a single passage through the cellophane coil of the dialyzer, revealed significant impairment of directed migration toward both complementary and bacterial chemoattractants. Moreover, the chemotactic properties of neutrophils obtained from dialyzed patients before HD were significantly lower than had been estimated in 15 nondialyzed patients with chronic renal failure. The results confirm HD-induced complement activation and might explain the mechanisms of the increased susceptibility of dialyzed patients to bacterial infections.

Adult↗
PubMed2000

Histopathologic effects of cutaneous tape stripping in pigs.

OBJECTIVE: The stratum corneum (SC) is the major barrier to topical absorption of medications. Skin tape stripping (TS) removes the stratum corneum, allowing more rapid absorption of drugs such as local anesthetics. Prior to evaluating TS in human clinical trials, this study was performed to evaluate its immediate and delayed histopathologic effects in swine. METHODS: This was a prospective, interventional, longitudinal, experimental animal study using two isoflurane-anesthetized young swine. Cellophane tape was applied to the skin of clipped swine flanks and peeled away 10, 15, 20, 25, or 30 times. Each level of tape stripping was performed three times in each pig. Full-thickness biopsies were taken at 30 minutes and two weeks later for blinded histopathologic evaluation by a dermatopathologist using randomly ordered hematoxylin-and-eosin-stained tissue sections and conventional light microscopy. The absolute thickness of the cornified layer was measured and compared with normal (unstripped) cornified layer. RESULTS: Tape stripping up to 30 times produces thinning of the SC without detectable changes in the underlying epidermis and dermis at 30 minutes and 14 days post-stripping. The degree of thinning was proportional to the number of tape applications. Complete recovery of the cornified layer was noted at two weeks. There were no adverse effects, such as infection, scarring, or inflammatory cell infiltrates. CONCLUSIONS: Under the conditions studied, TS not only appears safe, but appears to produce no long-term sequelae.

Animals↗