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Biomedical subjects

C Wallis

Publications and source records attributed to C Wallis.

At least 127 records · Page 7Linked to original sources
PubMed1974

Environmental factors influencing isolation of enteroviruses from polluted surface waters.

The influence of water quality upon the concentration of virus on location was assessed in field studies conducted in the Houston ship channel, Galveston Bay, and Houston waste treatment plants. Clarification of polluted surface waters was accomplished with minimal loss of virus. Virus from clarified sewage effluents and saline waters was then adsorbed and concentrated on textile and membrane filter surfaces. Direct measurements of virus from large volumes of polluted surface waters under existing field conditions were then made using the virus concentrator equipment.

Adsorption↗
PubMed1974

Development of methods for detecting viruses in solid waste landfill leachates.

Methods were developed for detecting and concentrating enteric viruses in municipal solid waste landfill leachates. Poliovirus added to a leachate was not readily detectable, possibly because the virus was adsorbed to the leachate particulates. The masking effects associated with suspended solids in the leachate were overcome by adding a final 0.1 M sodium (tetra)ethylenediaminetetraacetate concentration to the leachate. A sodium (tetra)ethylenediaminetetraacetate-treated leachate could be clarified by filtration at pH 8.0 without a loss of virus. The clarified and sodium (tetra)ethylenediaminetetraacetate-treated leachate contained interfering materials of an anionic nature which prevented virus adsorption to epoxy-fiber glass filters. This interfering effect was overcome by treating the leachate with an anion-exchange resin. Viruses in the resin-treated leachate were concentrated by adjusting the leachate to pH 3.5, adding AlCl(3) to a final 0.005 M concentration, adsorbing the viruses to an epoxy-fiber glass virus adsorbent, and eluting the adsorbed viruses in a small volume. When this method was used to concentrate poliovirus 100-fold in a variety of leachates, the average virus recovery efficiency was 37%. With the methods described in this study, it should be possible to efficiently monitor solid waste disposal site leachates for enteric viruses.

Adsorption↗
PubMed1974

Chemical disinfection of holding-tank sewage.

A number of chemical disinfectants were evaluated for their bactericidal and virucidal effectiveness in holding-tank sewage. It was found that the disinfection efficiencies of formaldehyde, benzalkonium chloride, cetylpyridinium chloride, and methylene blue were markedly improved if the pH of the sewage was raised from 8.0 to 10.5. When formaldehyde, benzalkonium chloride, and methylene blue were tested with either 2-week holding times with no sewage additions or 10-day holding times with daily sewage additions, disinfection effectiveness was maintained as long as the sewage pH was kept at 10.5 and the disinfectant concentration was kept at 100 mg/liter or more. Calcium hypochlorite, zinc sulfate, and phenol were found to be relatively ineffective disinfectants for holding-tank sewage.

Bacteria↗
PubMed1973

Acid sensitivity of the influenza virus hemagglutinin.

Influenza virus hemagglutinin was shown to be acid resistant if precipitates which form during acidification are first removed. Adsorption of virus to precipitates formed during acidification may cause a virus to be described incorrectly as acid sensitive.

Adsorption↗
PubMed1973

Concentration of enteroviruses from large volumes of water.

An improved method for concentrating viruses from large volumes of clean waters is described. It was found that, by acidification, viruses in large volumes of water could be efficiently adsorbed to epoxy-fiber-glass and nitrocellulose filters in the absence of exogenously added salts. Based upon this finding, a modified version of our previously described virus concentration system was developed for virus monitoring of clean waters. In this procedure the water being tested is acidified by injection of N HCl prior to passage through a virus adsorber consisting of a fiber-glass cartridge depth filter and an epoxy-fiber-glass membrane filter in series. The adsorbed viruses are then eluted with a 1-liter volume of pH 11.5 eluent and reconcentrated by adsorption to and elution from a small epoxy-fiber-glass filter series. With this method small quantities of poliovirus in 100-gallon (378.5-liter) volumes of tapwater were concentrated nearly 40,000-fold with an average virus recovery efficiency of 77%.

Journal Article↗
PubMed1972

Enterovirus concentration on cellulose membranes.

Cellulose nitrate membranes were used as one of the adsorbents in concentrating viruses from water. For adsorption to occur, salts were required. With increase in valency of salt, less salt was necessary for enhanced virus adsorption to membranes. Trivalent salts were more effective because they could be used at only 1% the concentration required for divalent salts. Thus, 0.5 mM AlCl(3) was as effective as 50 mM MgCl(2). For testing 500 gal of water, only 0.24 kg of AlCl(3) was required in contrast to 20 kg of MgCl(2). Virus could then be eluted from such membranes, having an area of 486 cm(2), with 250 ml of pH 11.5 buffer. Lowering the pH of the eluate and adding AlCl(3) permitted the virus to be quickly readsorbed on a smaller cellulose membrane, i.e., 4 cm(2). Virus for assay was eluted from the small membrane in 1 ml. This procedure has provided the basis for concentrating minute amounts of virus from large volumes of water.

Adsorption↗
PubMed1972

Concentration and purification of influenza virus on insoluble polyelectrolytes.

A method for rapid concentration and purification of influenza virus by adsorption on and elution from an insoluble polyelectrolyte is described. To accomplish this task, influenza virus had to be rendered stable at pH 4 to 5, since viruses adsorb to the polyelectrolyte more efficiently at this pH range. A precipitate which forms in influenza harvests under acid conditions in the cold can be removed by ammonium sulfate at a concentration which traps the precipitate but not the virus. Thus, ammonium sulfate-treated influenza virus in allantoic fluid could be readily concentrated on the polyelectrolyte. Elution yielded a virus concentrate essentially free of nonviral proteins.

Adsorption↗
PubMed1972

Photodynamic treatment of herpes keratitis.

Photodynamic inactivation of virus was tested as a potential therapeutic tool for herpesvirus-induced keratitis, which is a leading cause of blindness and disability. Experimental keratitis produced in rabbits by infection with herpesvirus isolated from a human periorbital lesion was treated with proflavine and light. The herpetic keratitis could be rapidly resolved by the dye-light treatment, whereas improvement was not seen in untreated rabbits, nor in those treated with light alone or dye alone.

Acridines↗
PubMed1972

Detection of protein contaminants in biological preparations by discontinuous counterimmunoelectrophoresis.

Acidic proteins (serum albumin through beta(2) globulin) can be rapidly detected by the discontinuous counterimmunoelectrophoresis method in which the protein under test is allowed to react electrophoretically with specific antiserum. In the test, acidic proteins move towards the anode and cross over antibodies moving towards the cathode. The method is several thousand times more sensitive than the Lowry test, for it can detect picogram amounts of protein. With this method, foreign proteins (chicken allantoic fluids or bovine serum) were detected in virus vaccines manufactured for human use and in commercial "monospecific" immunological reagents.

Allantoin↗
PubMed1971

Concentration and purification of viruses by adsorption to and elution from insoluble polyelectrolytes.

Acid-resistant, nonenveloped viruses belonging to the enterovirus, reovirus, and adenovirus groups were readily concentrated on PE60, an insoluble cross-linked polyelectrolyte based on isobutylene maleic anhydride. Hydrolysis of PE60 by NaOH increased its capacity to adsorb viruses. Hydrogen ion levels played an important role in virus concentration; optimal pH levels for maximal virus adsorption were between pH 3.0 and 4.5. Undiluted virus was easily concentrated from large volumes on PE60, and the adsorbed virus was readily eluted at pH 8 to 9.

Adenoviridae↗
PubMed1971

Enhanced detection of Australia antigen in serum hepatitis patients by discontinuous counter-immunoelectrophoresis.

The use of discontinuous counter-immunoelectrophoresis enhanced the reaction between Au/SH antigen and its antibody in agarose. The ionic strength of the Veronal buffer used in the agarose was 0.015 mu, whereas 0.075 mu Veronal (both pH 8.6) was used for anode and cathode buffers. Electroendosmosis is increased under such conditions. Au/SH antigen and antibody reacted to give sharp lines within 30 to 45 min as compared with conventional counter-immunoelectrophoresis which required 1 to 3 hr or longer.

Hepatitis B↗