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Biomedical subjects

E A Hall

Publications and source records attributed to E A Hall.

35 records · Page 2Linked to original sources
PubMed1988

The nature of biotechnology.

This review introduces the multidisciplinary subject of biotechnology and the exploitation of the 'biomolecule'. The author describes practical applications of micro-organisms and biologically derived molecules. Some of these processes have been known for many years but recent developments have led to very rapid expansion of understanding and knowledge of the subject. Areas of the technology discussed include monoclonal antibodies, gene manipulation, enzymes, cell cultures, biosensors and biological processing products.

Animals↗
PubMed1988

Halothane interference at an amperometric oxygen electrode: the development of an oxygen/halothane sensor.

The role of electrode materials in the reduction of halothane and oxygen mixtures at rotating and stationary electrodes is considered. Halothane is found to be electroactive within the available electrode-potential range on silver and on gold. Double potential step experiments are considered in order to isolate the individual halothane and oxygen signals. A double integration, single potential step technique is evaluated for the quantitative simultaneous measurements of oxygen and halothane on gold. The influence of electrode purity is discussed in terms of a reaction mechanism and electrode output error.

Calibration↗
PubMed1988

A comparative study of the Seiko P-3 and Varilux 2 progressive addition lenses.

Forty patients were selected to participate in a double-masked comparative study of the Seiko Plax 3 (P-3) and Varilux 2 progressive addition lenses. The study was designed to determine patient preference for either lens design. The patients wore each lens for 1 month. Following each period, a questionnaire relating to the patient's impressions of the lenses was completed. After both wearing periods, the patient's preference was determined. The results show that 89.7% of the patients preferred the Seiko lens over the Varilux. Further, 82.4% chose the Seiko lens and 44.1% chose the Varilux lens over their habitual multifocal design. The results of this study show that, in addition to a preference for the Seiko P-3 design, both progressive addition lenses are viable alternatives to the conventional multifocal lens.

Aged↗
PubMed1986

Isolation and characterization of the apolipoprotein E receptor from canine and human liver.

Previous results have demonstrated that liver membranes possess two distinct lipoprotein receptors: a low density lipoprotein (LDL) receptor that binds lipoproteins containing either apolipoprotein (apo-) B or apo-E, and an apo-E-specific receptor that binds apo-E-containing lipoproteins, but not the apo-B-containing LDL. This study reports the isolation and purification of apo-B,E(LDL) and apo-E receptors from canine and human liver membranes. The receptors were solubilized with the zwitterionic detergent 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate and were partially purified by DEAE-cellulose chromatography. The apo-B,E(LDL) receptor was isolated by affinity chromatography on LDL-Sepharose. The apo-E receptor, which did not bind to the LDL-Sepharose column, was then purified by using an HDLc (cholesterol-induced high density lipoprotein)-Sepharose affinity column and an immunoaffinity column. Characterization of the receptors revealed that the hepatic apo-B,E(LDL) receptor is similar to the extrahepatic LDL receptor with an apparent Mr = 130,000 on non-reducing sodium dodecyl sulfate-polyacrylamide gels. The apo-E receptor was found to be distinct from the apo-B,E(LDL) receptor, with an apparent Mr = 56,000. The purified apo-E receptor displayed Ca2+-dependent binding to apo-E-containing lipoproteins and did not bind to LDL or chemically modified apo-E HDLc. Antibodies raised against the apo-B,E(LDL) receptor cross-reacted with the apo-E receptor. However, an antibody prepared against the apo-E receptor did not react with the apo-B,E(LDL) receptor. The apo-E receptor also differed from the apo-B,E(LDL) receptor in amino acid composition, indicating that the apo-E receptor and the apo-B,E(LDL) receptor are two distinct proteins. Immunoblot characterization with anti-apo-E receptor immunoglobulin G indicated that the apo-E receptor is present in the hepatic membranes of man, dogs, rats, and mice and is localized to the rat liver parenchymal cells.

Amino Acids↗
PubMed1985

Interleukin 3 promotes erythroid burst formation in "serum-free" cultures without detectable erythropoietin.

Erythroid burst-forming units (BFU-E) from mouse bone marrow were grown for 7 days in agar or serum-free methylcellulose cultures in the presence or absence of erythropoietin (Ep) and/or interleukin 3 (IL-3). It was found that IL-3, even in the absence of serum and detectable Ep, was able to stimulate the full development of many erythroid bursts. This IL-3 effect was cell-dose dependent and did not appear to correlate with Ep dose. Spontaneous bursts and those stimulated by Ep only were rare and when seen were very small relative to those produced by IL-3 or IL-3 plus Ep. When addition of IL-3 or Ep to 7-day cultures was delayed, IL-3 but not Ep was shown to maintain BFU-E. No evidence was found by radioimmunoassay that Ep was produced or released in 7-day, "serum-free" cultures of bone marrow nor was Ep activity detected in culture media except those to which it had been added deliberately.

Animals↗
PubMed1984

In vitro studies of erythropoietic progenitors (CFU-E) in marrow from neonatal and young mice.

Reports that cells from neonatal animals produce CFU-E in response to erythropoietin (Ep) at doses lower than are required by adults indicated that young mice would provide a good system to study the hormone response of erythropoietic progenitors. Studies presented here confirm the increased Ep responsiveness until 3-4 weeks of age reported previously by others. Along with the enhancement in their Ep responsiveness, bone marrow cells from young animals produce many more CFU-E per 10(5) cells plated than do adult animals; i.e., neonates have a higher plating efficiency for CFU-E in the presence of erythropoietin. Neonatal animals, in contrast to adults, contain in addition erythropoietic progenitors in their bone marrow capable of growth in vitro without added hormone. Because of the large numbers of "endogenous" colonies, a study was done to explore the possibility that a small amount of Ep was present in the culture medium. Antiserum to erythropoietin was added directly to cultures in another study to remove any undetected hormone. The results indicate that CFU-E from neonatal mouse bone marrow can develop in culture in the absence of detectable Ep.

Aging↗
PubMed1982

A sandwich electrode for multi-gas analysis: a prototype.

A prototype composite electrode consisting of a metallized membrane "outer" cathode, and a conventional "inner" silver disc cathode, both sharing the same electrolyte, is described. Preliminary results indicate that the metallized membrane will act as an oxygen filter, allowing anaesthetic gases such as nitrous oxide, to pass through to the second (inner) cathode, where they may be reduced. Linear relationships exist for oxygen concentration and metallized membrane current; and for nitrous oxide concentration and the second cathodic current. Extension of this technique to measure both halothane and nitrous oxide on the second cathode, simultaneously with oxygen on the metallized membrane, is discussed.

Electrodes↗
PubMed1976

Antiprotozoal activity in citrinin.

Citrinin has an inhibitory effect on growth of T. pyriformis. Citrinin also caused a shift to smaller cell size, particularly at the higher concentrations (25, 50 and 100 mug/ml). The mycotoxin exerted only a marginal effect on the respiration of T. pyriformis; but citrinin (25 mug/ml) induced an inhibitory effect on DNA, RNA and protein content. The greatest decrease was in RNA, while smaller decreases in protein and DNA were observed. A bioassay employing T. pyriformis was determined; the lower limit of citrinin detection was between 1 and 5 mug/ml.

Animals↗
PubMed1965

The linkage between the polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei.

1. The linkage between the polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei is rapidly hydrolysed under mild acid-hydrolysis conditions. 2. The release of the polysaccharide is accompanied by the hydrolysis of an N-acetylhexosaminide linkage. The N-acetylhexosamine residue readily forms chromogen and it is concluded that it is substituted on C((3)) by the adjacent sugar. 3. Continued heating of the polysaccharide in acid results in a slower release of reactive N-acetylhexosamine due to the hydrolysis of glycosidic linkages within the polysaccharide. 4. After the linkage between the polysaccharide and mucopeptide has been hydrolysed, acid phosphatase will release approx. 40% of the total phosphorus as inorganic phosphate. 5. It is concluded that the polysaccharide component of the cell wall is joined through its reducing end group to a phosphate grouping in the mucopeptide.

Acid Phosphatase↗
PubMed1965

Properties of the polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei.

1. The polysaccharide and mucopeptide components of the cell wall of Lactobacillus casei have been separated by mild conditions of acid hydrolysis. 2. Removal of the polysaccharide renders the mucopeptide susceptible to lysozyme. 3. The mucopeptide and polysaccharide components have been analysed and the results compared with those obtained previously. 4. The polysaccharides responsible for group specificity have a terminal reducing N-acetylgalactosamine residue substituted on C((3)) by the adjacent sugar; estimation of this component gave an indication of the molecular weight of the polysaccharides. 5. Evidence has been obtained for the presence of rhamnosyl-(1-->3)-N-acetylgalactosamine among the products of acid hydrolysis of the group B polysaccharide.

Amino Sugars↗
PubMedDate not supplied

Immunologic and hematologic consequences in mice of exposure to ozone.

Immunologic and hematologic effects of continuous, chronic exposure of mice to ozone are reported. A consistent decrease was found in ability of spleen cells from exposed mice to engage in primary antibody formation. Results from an investigation of the possible presence of suppressor cells were inconclusive Separation of spleen cells into adherent and nonadherent populations revealed suggestive differences between normal and ozone-exposed mice. Among myelopoietic progenitors examined, CFU-S, CFU-GM, CFU-E, CFU-ME, and BFU-E, only the last two named were found to be altered after ozone exposure. The possible bases and implications of these findings are discussed.

Animals↗