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At least 289 records · Page 16Linked to original sources
PubMed1992

Aggregation of Escherichia coli B/r A during agar filtration: effect on morphometric measurements.

We have investigated the phenomenon of particle aggregation in a sample of 71,038 Escherichia coli B/r A cells in balanced exponential growth, during preparation for electron microscopy by agar filtration. The bacteria were photographed in a transmission electron microscope and the dimensions and spatial relationships among all the members of each aggregate were recorded using an interactive image processing system. The proportion of aggregated cells, 22%, is much greater than that found by direct count in a light microscope (7%), implying that most aggregation takes place during the preparation stages. The aggregated cells are about 1% narrower than the free cells, because of mutual compression, and 1.5% longer, because of a selection bias in favor of longer cells. From a statistical analysis of the data, we conclude that the clustering of cells into aggregates in the course of sample preparation is the result of random encounters during the settling on the collodion membrane and of the changing surface tension during the drying process. A method is proposed to correct morphometric measurements for the distortion caused by cellular aggregation of this kind.

Agar↗
PubMed1988

Dynamic hydration effects in an electron microscope cold stage.

Water can be a substantial proportion of the residual gas in modern electron microscopes even when frozen hydrated specimens are not used. During measurements of the mass thickness of thin collodion film specimens at low temperatures, it was found that a volatile surface layer (condensed water) modified the apparent rate of mass loss induced by radiation exposure. Mass loss can be enhanced by the presence of water (specimen "etching"), or mass loss can be masked by the dynamic adsorption of water to the specimen surface. The microscope or the grid can be a secondary source of the water; even with cold anticontaminator plates in the vicinity of the specimen, water can be desorbed by x-rays or backscattered electrons. In one typical situation, the mass loss rate appears reduced (due to water adsorption), but the ultimate damage is greater (due to etching). These results illustrate that care must be taken in interpreting mass thickness measurements made in the presence of water and that the lowest stage temperature does not necessarily produce the best observation conditions for all specimens.

Freezing↗
PubMed1984

Pharmacokinetics of gliclazide in healthy and diabetic subjects.

The pharmacokinetics of total and free gliclazide, 1-(3-azabicyclo[3,3,0]oct-3-yl)-3-(p-tolylsulfonyl)urea, a potential hypoglycemic drug, was studied in healthy (n = 12) and diabetic (n = 12) subjects. The serum level of gliclazide was determined by a high-performance liquid chromatographic method (HPLC). The free fraction of gliclazide was obtained from serum by an ultrafiltration technique using a collodion membrane. The mean adsorption of gliclazide to the membrane was approximately 50% when the membrane was used more than twice. Therefore, the gliclazide level in the filtrate was corrected by doubling the apparent value. The ratio of gliclazide-protein binding remained constant at approximately 92% in serum after administration to healthy and diabetic subjects. The mean pharmacokinetic parameters of elimination rate (ke), time to reach the peak level (tmax), elimination half-life (t 1/2), and volume of distribution (Vd) were 0.07 h-1, 2.8 h, 12.3 h, and 17.4 L, respectively. The parameters did not differ significantly between healthy and diabetic subjects or between single and successive administrations; moreover, they did not differ between the free and total drug level. Although there were intersubject variations, the therapeutic effects of oral administration of gliclazide on serum glucose and insulin levels were found in four diabetic patients. The results of this study show that the pharmacokinetics of the total gliclazide level reflect those of the free gliclazide in serum.

Adult↗
PubMed1996

Germination of Phyllosticta ampelicidaPycnidiospores: Prerequisite of Adhesion to the Substratum and the Relationship of Substratum Wettability

Pycnidiospores of Phyllosticta ampelicida, the causal agent of black rot of grape, were found to germinate only on substrata on which they were firmly attached. Such surfaces were poorly wettable and had advancing contact angles (straight thetaa) formed by a water drop of >80&deg;, e.g., grape leaf, polystyrene, Teflon, polycarbonate, collodion, and glass treated with the silanes n-octadecyltrichlorosilane, dimethyldichlorosilane, or diphenyldichlorosilane. When pycnidiospores were deposited on more wettable surfaces they did not attach firmly and did not germinate. Such highly wettable surfaces had straight thetaa </= 40&deg; and were represented by heat-treated glass, cellophane, nutrient- and water-agars, polystyrene treated with UV-irradiation or sulfuric acid, and glass silanized with n-2-aminoethyl-3-aminopropyltrimethoxysilane, n-(trimethoxysilylpropyl)ethylenediamine triacetic acid trisodium, or 3-aminopropyltriethoxysilane. Adhesion of pycnidiospores was assessed with and without a hydraulic shearing force. Pycnidiospore adhesion occurred over several minutes in distilled deionized water, unless it was first acidified, which decreased attachment time to <0.03 s. Attachment of pycnidiospores treated with sodium azide, formaldehyde, or boiled in water for 10 min was similar to nontreated conidia. Possible mechanisms of adhesion of the conidia to surfaces include hydrophobic and ionic interactions.

Journal Article↗
PubMed1994

Characterization of rotavirus VP2 particles.

Rotavirus particles consist of three concentric proteinaceous capsid layers. The innermost capsid (core) is made of VP2. The genomic RNA and the two minor proteins VP1 and VP3 are encapsidated within this layer. Empty rVP2 particles are produced when insect cells are infected with a recombinant baculovirus which contains the bovine Rf rotavirus gene 2 (Labbé et al., 1991, J. Virol. 65, 2946-2952). Analysis of expressed rVP2 particles by SDS-PAGE showed these particles were composed of three major VP2-related proteins, called bands A, B, and C, with apparent molecular weights of 94K, 85K, and 77K, respectively. N-Terminal amino acid sequence analysis of each band showed that band A and band B were blocked, and band C lacked 92 amino acids from the N terminus. Bands B and C were predicted to also lack an approximately 10K peptide fragment from the C terminus. Electron microscopy (EM) showed negatively stained rVP2 particles to be spherical with icosahedral symmetry, 520 +/- 20 A in diameter. Highly concentrated rVP2 particles were converted to unusual forms, including elongated bristly structures, helix-like structures, and sheet-like helix structures. These unusual forms apparently resulted from a structural conversion of individual rVP2 particles. This conversion was reversible both in solution or on a collodion-carbon-coated grid support. The reconstituted rVP2 particles possessed normal morphology and reacted with purified VP6 to form rVP2/6 empty double-layered (previously called single-shelled) virus-like particles with an association constant Ka approximately 10(11) M-1. Native viral core particles lacking RNA were obtained by dialysis of full cores prepared from purified SA11-4F rotavirus double-layered particles against a hypotonic buffer in the presence of EDTA. EM showed both the full and empty native viral cores to be spherical with icosahedral symmetry. Highly concentrated SA11-4F full and empty cores also were converted into elongated and bead-like structures. However, in contrast to rVP2 particles, the conversion of SA11-4F cores was not reversible. These results provide some helpful clues to understanding VP2 functions, the assembly of VP2 particles, the assembly of VP2/6 double-layered particles, and the transport of metabolites inside and outside of the core particle.

Amino Acid Sequence↗
PubMed1985

Immunosuppressor control as a modality of cancer treatment: effect of plasma adsorption with Staphylococcus aureus protein A.

In tumor-bearing hosts both cellular and humoral tumor-growth-enhancing factors are present. They cause immunosuppression and facilitate the growth of tumors. Very early during tumor growth these factors are either elicited by the tumor cells or induced by the host immunocytes. Among these immunosuppressive agents, circulating immune complexes appear to play a predominant role. They also activate suppressor cell activity. Plasma adsorption of CIC and IgG by protein A of Staphylococcus aureus has been reported to cause tumor regression. Plasma adsorption with protein A-collodion charcoal, protein A-silica, or protein A-Sepharose also induced tumorilytic reactions. Even direct infusion of protein A induced tumor regressions in rat mammary tumors. Recent studies showing tumor regressions following S. aureus Wood 46 plasma adsorption or infusion of normal plasma adsorbed over S. aureus indicate that specific blocking factor removal by plasma adsorption may not be the mechanism for causing tumor destruction. Results indicate that S. aureus plasma adsorption leaches a number of staphylococcal agents. Thus, it appears that staphylococcal agents, protein A, enterotoxin, and other factors are responsible for the induction of reactions leading to tumor destruction. A unified mechanism explaining the results obtained with plasma adsorption using protein A of S. aureus, or S. aureus Wood, or direct protein A infusion, was presented.

Animals↗
PubMed1980

[Preliminary study of stages of human meiosis in spermatocytes and ovocytes (author's transl)].

Human meiotic chromosomes, from spermatocytes and ovocytes, are described after observations of whole mount preparations under E.M. Small testicular and ovarian fragments are put in distillated water, then macerated; the cell suspension is spread on the surface of sheet copper grids covered with formvar plus collodion films. After dehydratation interesting stages are selected under L.M. before observations under E.M. Zygotene and pachytene are the most common stages. During pachytene the chromomeres are well individualized; the synaptonemal complex may be observed; chromatin fibers connect the chromosomes to nuclear pores, interchromosomal fibers joint the bivalents. Zygotene and pachytene bivalents are very similar in the male and the feminine germ cells.

Chromatin↗
PubMed1976

[Hemoperfusion by means of encapsuled charcoal for the treatment of exogenous and endogenous intoxications].

The method developed by Chang for using in collodion and albumin encapsuled charcoal as artificial cells for hemoperfusion has been studied in vitro. The capacity for the absorption of more or less dialysable exogenous substances (barbiturate, Diazepam, Parathion) and an endogenous toxic metabolite (p-hydroxyphenyl acetic acid) has been examined. With the absorption unit one can eliminate 80 to 90 per cent of the initial concentration of barbiturate, Diazepam and p-hydroxyphenyl acetic acid in about 90 min, of Parathion about 50 per cent in the same time, whereas bromide and ammonia are not absorbed. Attempts to avoid regional heparinisation by the incorporation of heparin into the capsule of charcoal granules were not successful. Assuming correct preparation of the hemoperfusion system, observance of steril precoutions and regional heparinisation, the use of the "detoxication shunt" is a promising means in the treatment of severe exogenous and endogenous intoxications which are not accessible by conventional therapeutic means.

Adsorption↗
PubMed1996

Electrogenicity at the donor/acceptor sides of cyanobacterial photosystem I.

To study electrogenesis the photosystem I particles from Synechococcus elongatus were incorporated into asolectin liposomes, and fast kinetics of laser flash-induced electric potential difference generation has been measured by a direct electrometric method in proteoliposomes absorbed on a phospholipid-impregnated collodion film. The photoelectric response has been found to involve three electrogenic stages associated with (i) iron-sulfur center Fx reduction by the primary electron donor P700, (ii) electron transfer between iron-sulfur centers Fx and FA/FB, and (iii) reduction of photo-oxidized P700+ by reduced cytochrome C553. The relative magnitudes of phases (ii) and (iii) comprised about 20% of phase (i).

Crystallography, X-Ray↗
PubMed1984

Artificial cell-microencapsulated phenylalanine ammonia-lyase.

Phenylalanine ammonia-lyase (PAL) is immobilized in collodion artificial cells. Once technical problems associated with the encapsulation of this enzyme were solved, the enzyme kinetics were compared to PAL in free solution. Microencapsulated PAL has an apparent enzyme activity that is 20% of the activity of enzyme in free solution. The Km for both free and immobilized PAL is 475 microM. The Vm for the microencapsulated PAL is 9 microM/min, whereas that of PAL in free solution is 55 microM/min.

Ammonia-Lyases↗
PubMed2006

[Congenital ectropion in ichthyosis congenita mitis and gravis].

BACKGROUND: Congenital ichthyosis is a generalized hyperkeratinization of the skin at birth. Depending on clinical aspects and severity, three forms of congenital ichthyosis have been defined: mitis, tarda, and gravis. Desquamation of the parchment-like hyperkeratinized skin begins shortly after birth and may require several weeks to complete. Skin alterations in the eyelid cause shortening of the anterior lamella, subsequently resulting in ectropion. This affects the upper eyelid more often than the lower and can lead to complications such as chronic palpebral or bulbar conjunctivitis and keratinization or exposure keratopathy. Here we present two case reports illustrating the course of ichthyosis congenita mitis and gravis. PATIENTS AND METHODS: Patient 1 (ichthyosis congenita mitis): a male baby prematurely born at 34+2 weeks of gestation was delivered by cesarean section. The entire body was covered by a parchment-like hyperkeratinized skin. Both eyes showed ectropion of the upper and the lower eyelid, which was more obvious with enforced lid closure. Frequent application of external ointment and spontaneous desquamation led to resolution of the ectropion. Patient 2 (ichthyosis congenita gravis): a male baby prematurely born at 35+4 weeks of gestation was delivered by cesarean section. At birth the child showed the signs of a collodion baby with ectropion of all four eyelids in combination with a characteristic "fish mouth" and rudimentary external ears. The child died on the 14th day of life of septicaemia. CONCLUSION: In mild forms of congenital ichthyosis surgical treatment of eyelid ectropion is not required. In more severe cases a skin graft may become necessary. Various although limited sources of graft material which are discussed can be considered.

Abnormalities, Multiple↗
PubMed1984

Coupling of membrane-bound and detergent-solubilized sodium- and potassium-activated ATPase to p-benzoquinone-treated microtiter plates.

Membrane-bound and dodecyloctaoxyethyleneglycol monoether-solubilized Na,K-ATPases from pig kidney were covalently attached to microtiter plate wells pretreated with p-benzoquinone (plus collodion for some plates). The immobilized enzymes were detected with the mouse monoclonal antibody (named 38) specific to Na,K-ATPase and a perioxidase-conjugated rabbit IgG anti-mouse IgG. When the two Na,K-ATPase preparations were applied to each well at the same protein concentration, the color intensity of the peroxidase reaction for determination of antibody was two to three times stronger with the solubilized enzyme than with the membrane-bound enzyme. Similar titer values were obtained from the graphical analysis of titration curves of both enzymes. Red cell membrane proteins as well as Na,K-ATPase were covalently attached to the plastic. p-Benzoquinone should be generally useful for coupling membrane proteins, even in detergent solutions, to microtiter plate wells.

Animals↗
PubMed1992

Chronic intracerebral infusions of vasopressin and vasopressin antagonist modulate social recognition in rat.

To assess the role of androgen-dependent brain vasopressinergic transmission in the modulation of social recognition, castrated male rats which are deficient in vasopressin were implanted intracerebroventricularly with an Accurel collodion mini-device containing 10 micrograms vasopressin (AVP) whereas intact male rats were implanted with a similar device containing 50 micrograms of 1-deaminopenicillamine 2-O-methyltyrosine arginine vasopressin (dPTyr(Me)AVP), a specific antagonist of the vasopressor like receptors of vasopressin. Control rats in each experimental group were implanted with an Accurel device containing water. Castrated rats treated with AVP explored familiar juvenile conspecifics in the same manner as intact male rats. Conversely, intact male rats treated with dPTyr(Me)AVP explored familiar juveniles in the same manner as castrated male rats. These results confirm the role of androgen-dependent vasopressinergic neurotransmission in social recognition.

Analysis of Variance↗
PubMed1993

Determination of 10-20 system electrode locations using magnetic resonance image scanning with markers.

We determined locations of 33 scalp electrodes used for electroencephalographic (EEG) recording by placing markers in the positions determined by the 10-20 system and performing magnetic resonance image (MRI) scanning on volunteer subjects. Small Vaseline-filled capsules glued on the scalp with collodion produced easily delineated regions of increased signal on standard MRI head images. Measurements of each capsule's coordinates in 3 dimensions were made from MRI scans. A spherical surface was fitted through the marker positions, giving an average radius and an origin (center of sphere). The coordinate axes were rotated to ensure that electrode Cz was on the z-axis and that the y-axis was oriented in the posterior-anterior direction. Two spherical (angular) coordinates were determined for each electrode. Spherical electrode coordinates for different subjects differed by less than 20 degrees in all cases. An average and standard deviation of the spherical coordinates were calculated for each electrode. Standard deviations of several degrees were obtained. The average spherical coordinates obtained were close to those expected on the basis of applying the 10-20 system of placement to an ideal sphere. These measurements provide data necessary for various analyses of EEG performed to help localize epileptic foci.

Brain↗
PubMed1994

Electrogenicity at the secondary quinone acceptor site of cyanobacterial photosystem II.

Flash-induced generation of the electric potential difference (delta psi) by a direct electrometrical method was studied in Anacystis nidulans photosystem II-containing proteoliposomes associated with a phospholipid-impregnated collodion film. Besides a rapid phase of delta psi generation corresponding to charge separation between P680 and QA, an additional electrogenic phase with a characteristic time of 0.27 ms at pH 7.0 was observed after the second laser flash. The maximal amplitude of this phase was approx. 4% of that related to the P680+QA- formation. The sensitivity of this phase to DCMU, the flash-number dependence of its amplitude as well as the amplitude and the rate constant pH-dependences, indicate that it is due to the dismutation of QA- and QB- and to subsequent protonation of a doubly reduced plastoquinone QB2-.

Cyanobacteria↗
PubMed1983

Radioimmunoassays for protein A of Staphylococcus aureus.

Radioimmunoassays have been developed that can detect nanogram amounts of protein A (SpA), a product generated by Staphylococcus aureus that binds selectively to the Fc region of IgG from most mammalian species. Competition assays for fluid phase SpA utilize antibodies produced in chickens, 125I-labeled SpA as the tracer molecule, and either F(ab')2 fragments of rabbit IgG anti-chicken IgG or 40% ammonium sulfate as the precipitating agent to separate antigen-antibody complexes from free antigen. The double antibody assay could be carried out in serum from species that form only soluble complexes with SpA (e.g., rabbit), that react poorly with SpA (e.g., rat), or under appropriate conditions in serum from species (e.g., dog) that show high reactivity with SpA and form precipitating complexes. Chicken antibodies prepared by affinity chromatography on SpA-Sepharose and labeled with 125I were used in a direct binding assay for SpA present either on the cell wall of Cowan strain I or Wood 46 bacteria, in insoluble complexes prepared from SpA and whole serum or purified IgG, or in Clq binding complexes that were formed by passage of serum from normal or tumor bearing humans or dogs over SpA-collodion charcoal. Since both types of assays could detect SpA even in the presence of serum or IgG, they offer advantages over other techniques in which the SpA-Fc interaction may interfere.

Animals↗
PubMed1990

Detection of single-stranded DNA in scrapie-infected brain by electron microscopy.

The nucleic acid content of enriched preparations of mitochondria/tubulofilamentous particles from normal and scrapie-infected hamster brains were examined by electron microscopy. After spreading on collodion-coated grids circular molecules of approximately 15.7 kb corresponding in size to mitochondrial DNA (mtDNA) were observed both in normal and scrapie-infected brains. In nucleic acid preparations from scrapie-infected brains multimeric mtDNA and single-stranded DNA strands of about 0.49 X 10(6) daltons were also visualized. These findings demonstrate the presence of a single-stranded DNA in scrapie-infected brains and are consistent with previous data based on enzyme digestion of nucleic acids isolated from scrapie-infected brains.

Animals↗
PubMed1988

Development of a sensor for non-invasive intracranial pressure measurement in the newborn.

A new system has been developed for the non-invasive monitoring of intracranial pressure (ICP) across the anterior fontanelle in the newborn. The system comprises a very small pneumatic sensor linked via two vinyl tubes to an instrument where the ICP value is displayed. The sensor is simply bonded to the anterior fontanelle, using industrial collodion normally used for attaching EEG electrodes. The sensor body is injection moulded in semi-flexible polyurethane with a very thin, compliant membrane bonded to its front surface. Using these manufacturing techniques the sensors are made to be disposable thus minimizing the risk of cross infection. ICP characteristics can now be recorded continuously in a wide range of neonates and the evaluation of currently used therapeutic treatments for lowering elevated ICP can be carried out safely and accurately.

Electrodes↗