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Biomedical subjects

G L Mills

Publications and source records attributed to G L Mills.

At least 19 recordsLinked to original sources
PubMed2003

Cyclooxygenase inhibitory and antioxidant compounds from the fruiting body of an edible mushroom, Agrocybe aegerita.

In the search for bioactive natural products from edible mushrooms, we have investigated the fruiting body of Agrocybe aegerita. The methanol extract of this mushroom yielded a fatty acid fraction (FAF), along with palmitic acid (1), ergosterol (2), 5,8-epidioxy-ergosta-6,22-dien-3beta-ol (3), mannitol (4) and trehalose (5). The composition of FAF was confirmed by GC-MS and by comparison to the retention values of authentic samples of palmitic, stearic, oleic and linoleic acids. The structures of 1-5 were established using spectroscopic methods. FAF and compounds 1-3 showed cyclooxygenase (COX) enzyme inhibitory and antioxidant activities. The inhibition values of liposome peroxidation by FAF, compounds 1 and 2 at 100 microg/ml were 75, 45, and 43%, respectively. The inhibition values of COX-I enzyme by FAF and 1-3 at 100 microg/ml were 80, 39, 19, and 57%, respectively. Similarly, COX-II enzyme activity was reduced by FAF and 1-3 at 100 microg/ml with values of 88, 45, 28, and 22%, respectively. Compounds 1, 3 and fatty acids were isolated here for the first time from the fruiting body of A. aegerita.

Agaricales↗
PubMed2001

Abiotic transformation of perchloroethylene in homogeneous dithionite solution and in suspensions of dithionite-treated clay minerals.

The reductive dechlorination of perchloroethylene (PCE) in homogeneous solutions of dithionite and at the surfaces of dithionite-citrate-bicarbonate (DCB) treated ferruginous smectite and Na-montmorillonite was studied. Transformation products of PCE identified in dosed dithionite-treated samples included TCE, DCE, 1,1,2-trichloroethane (TCA), 1,1-dichloroethane (DCA), chloroacetylene, acetylene, ethene, and ethane. The decomposition of dithionite to sulfate yielded both protons and electrons necessary for hydrodechlorination (hydrogenolysis) of PCE. Dithionite treatment of the Fe-poor Na-montmorillonite enhanced reductive dechlorination of PCE relative to dithionite-treated Fe-rich ferruginous smectite, within the range of 11.5-137.8 mM dithionite. For the same dithionite concentration, the kinetics of the heterogeneous reactions of PCE was generally faster than that of the homogeneous reaction, and higher concentrations of TCE were measured in the heterogeneous reactions. Interestingly, increases in the mass of the clay minerals used, the Fe2+ content in the clay mineral structure, or the dithionite concentration used did not necessarily enhance the abiotic transformation of PCE, as would otherwise be predicted. The most efficient reductive dechlorination of PCE was observed with 0.5% clay (m/v) treated with 34.5 mM dithionite buffered at pH 8.5. The solid-state transfer of electrons to surfaces and edges, rather than the redox capacity, limited the dechlorination of PCE by reduced ferruginous smectite and/or suspensions containing a higher clay mass. The greater reactivity of dithionite-reduced montmorillonite than similarly treated ferruginous smectite is attributed to (i) the well-documented layer collapse and aggregation of chemically reduced clays that increases with the clay's iron content, (ii) the location of solid-phase Fe2+ in the reduced clay mineral and whether it is accessible or inaccessible for reaction with PCE at the mineral edges and surfaces where the reactions are thought to occur, and (iii) the greater swellability of montmorillonite versus ferruginous smectite. The faster dechlorination rate of PCE observed with dithionite-reduced Fe-poor montmorillonite than similarly reduced iron-rich ferruginous smectite suggests that the use of dithionite barriers for in-situ treatment of chlorinated solvent plumes should not be limited to aquifers with Fe-rich sediments.

Aluminum Silicates↗
PubMed1988

Development of amphotericin B liposomes bearing antibody specific to Candida albicans.

Liposomes expressing external antibody specific for Candida albicans and encapsulating amphotericin B were developed and characterized in this study. Antibody was first modified by the covalent attachment of palmitic acid residues. Liposomes were produced by reverse-phase evaporation and modified antibody was incorporated into these liposomes via the hydrophobic interaction between the palmitic acid and the phospholipids composing the liposomes. The liposomes were characterized as to the amount of amphotericin B by spectroscopy and for the presence of antibody by protein analysis and secondary immunolabeling by fluorescent and electron microscopic methods. Immunogold labeling showed that the antibody was being expressed externally on the liposomes in the electron microscopic studies and the specificity of these liposomes for C. albicans was observed by secondary immunofluorescence.

Amphotericin B↗
PubMed1984

Chimpanzee serum lipoproteins. Isolation, characterisation and comparative aspects of the low density lipoprotein and apolipoprotein-BH.

Evaluation of the serum lipoprotein profile in non-fasting, adult chimpanzees by analytical ultracentrifugation revealed a lower mean LDL level (269 mg/dl) than typical of man. The major molecular form(s) of low density lipoprotein (LDL) was then isolated in the density interval 1.024-1.050 g/ml by sequential ultracentrifugation. The physicochemical properties of chimpanzee LDL, including net surface charge as judged by electrophoresis, molecular size (220 A) by electron microscopy, and chemical composition closely resembled those of man. The antigenic structures of chimpanzee and human LDL were essentially indistinguishable, since immunodiffusion against antiserum to either the human or ape lipoprotein produced a precipitin reaction of complete identity between the two antigens. By micro-immunoprecipitation, the immunological cross-reactivity of LDL from the two species was in the range 85-97%, depending on the nature of the assay.

Amino Acids↗
PubMed1984

Lipid and protein composition of the surface tegument from larvae of Taenia taeniaeformis.

A tegumental fraction from fully developed larvae of Taenia taeniaeformis was recovered by low speed centrifugation following incubation of the parasites in a 0.1% solution of digitonin. Scanning electron microscopy of the parasite carcass revealed no surface microtrichs, and transmission electron microscopy indicated that the subtegumental layer was undamaged. The tegumental fraction, judging from the distribution of 3H-Concanavalin A, was enriched for surface components, exhibited low succinic dehydrogenase activity, and an electron microscopic examination of the pellet showed a slightly expanded but intact distal tegumental layer. The fraction, which made up 3.0% of the dry weight of the parasite, consisted of 52% protein and 32% lipid. Thirty-three proteins, ranging in Mr from 9,000 to 276,000 daltons, were detected after sodium dodecyl sulfate solubilization and polyacrylamide gel electrophoresis. Seven of these proteins were glycoproteins. Cholesterol, phosphatidylethanolamine, phosphatidylserine, and glycosphingolipids were the major lipids.

Animals↗
PubMed1983

Isolation, characterization and comparative aspects of the major serum apolipoproteins, B-100 and AI, in the common marmoset, Callithrix jacchus.

The two major apolipoproteins of marmoset serum have been isolated and characterized, and on the basis of physicochemical and immunological criteria are homologous with the human AI and B-100 proteins. Marmoset apolipoprotein AI was the principal protein of high-density lipoproteins (HDL) and was purified by gel filtration chromatography and electrophoresis in alkaline-urea polyacrylamide gel followed by electrophoretic elution. Purified marmoset apolipoprotein AI displayed an Mr of approx. 27000, was polymorphic (five forms) on isoelectric focussing, with pI values in the range 4.8-5.0, and migrated similarly to human apolipoprotein AI in alkaline-urea gels. An overall resemblance was seen in the amino acid composition of marmoset apolipoprotein AI and that of its human counterpart with the notable exception that marmoset AI contained 1 isoleucine residue/mole. An immunological reaction of partial identity between the human and monkey proteins was seen upon immunodiffusion of their HDLs against antiserum to human apolipoprotein AI. Marmoset B-100 was the predominant apoprotein of VLDL and LDL, resembling the human protein in its elution profile on gel filtration chromatography in anionic detergent, and in its high apparent Mr (approx. 520000). The marmoset and human B-100 proteins were alike in amino acid composition and carbohydrate content. Moreover, their immunological behaviour with an antiserum to marmoset apolipoprotein B showed them to share certain antigenic determinant(s). We conclude that the physicochemical properties of the principle apolipoproteins of Callithrix jacchus, a New World primate, markedly resemble those of the human AI and B-100 proteins, suggesting therefore that they may function similarly in lipid transport and metabolism. Counterparts to human apolipoproteins AII, E, CII and CIII have also been tentatively identified.

Amino Acids↗
PubMed1983

Plasma lipids, lipoproteins and apoproteins in a case of apo C-II deficiency.

A new case of apo C-II deficiency is described. The patient had plasma triglyceride levels ranging from 10.2-30.5 mmol/l. Apo C-II deficiency was confirmed by gel electrophoresis, isoelectric focusing and immunochemistry. In this patient plasma lipoproteins were mainly chylomicrons and very low density lipoproteins, LDL and HDL levels being very low. Infusion of normal plasma effectively reduced plasma triglycerides and enhanced low density and high density lipoproteins cholesterol levels. These data suggest that in vivo a precursor-product relationship exists between triglyceride rich lipoproteins and LDL and HDL, and further stress the role of the lipoprotein lipase-apo C-II system in modulating these metabolic interconversions.

Apolipoprotein C-II↗
PubMed1983

Chemical composition of lipid droplets isolated from larvae of Taenia taeniaeformis.

Young developing larvae of Taenia taeniaeformis contain large deposits of osmiophilic droplets. These droplets are spherical, approximately 1.5 micron in diameter and are primarily localized in the tegument. After cellular disruption of the parasite, followed by centrifugation, the lipid droplets were found in a floating layer of lipid. The lipid droplets in the lipid layer resembled the droplets as seen in situ. The isolated lipid droplets mainly consisted of neutral lipids with triglycerides, sterol esters, sterols and free fatty acids being the major components. Smaller amounts of other neutral lipids were also present, as were glycolipids, phospholipids and protein. The lipid droplets were not membrane bound. The relationship between lipid droplets, lipid utilization and membrane synthesis during parasite growth is discussed.

Animals↗
PubMed1982

The emergency evacuation of a geriatrics hospital in Toxteth.

The evacuation of a 102-bed geriatrics hospital in the middle of the night and from the centre of a riot in Toxteth, Liverpool, is described, together with its effect on the patients involved. No increase in the mortality rate occurred during the six weeks following the evacuation, but a significant increase in morbidity was found. Specific recommendations are made for action to be taken should other city centre geriatrics hospitals need to be evacuated in similar circumstances.

Aged↗
PubMed1981

Measurement of urinary loss in elderly incontinent patients. A simple and accurate method.

A simple method which uses beam balance scales, a portable timer, a large plastic-backed absorbent pad, and tight fitting pants has been developed to measure urinary loss in incontinent patients. Complete collection of all the urine lost was achieved in 220 (94%) of 234 incontinent episodes in patients from three long-term-care wards. The attendant's subjective assessment of "wetness", as used in other methods, was shown to be an extremely crude indicator of the degree of incontinence since the weight-gain in pads judged subjectively as being "wet" was anything from 0.7 to 341 g and there was considerable overlap between the weights of pads judged to be "dry", "damp", or "wet". In 6 healthy volunteers the mean weight-gain per pad caused by perspiration was 1.2 g/2 h and the mean change due to evaporation/leakage, determined by means of pre-wetted pads, was 1.0 g.

Aged↗
PubMed1981

Lipid composition of metacestodes of Taenia taeniaeformis and lipid changes during growth.

A lipid analysis was performed on developing metacestodes of Taenia taeniaeformis removed from the livers of rats at times varying from 3 to 35 weeks post infection. Lipid accounted for 7-21% of the dry weight of the parasites. The highest proportions were found at the earlier stages. The distribution was as follows; neutral lipid 27-45%; glycolipid 5-11%; and phospholipid 50-61%. The major neutral lipid was cholesterol, and minor neutral lipids were sterol esters, triglycerides, diglycerides and monoglycerides. Hydrocarbons were present throughout development, but in the highest amounts at the earlier stages. Five different glycolipids were found, all of which were identified as glycosphingolipids. An increase in the proportion of more complex glycolipids was noted as parasites grew older. Ten different phospholipids were identified, with the major components being phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Other phospholipids were: lysophosphatides, phosphatidylinositol, phosphatidic acid, diphosphatidylglycerol, sphingomyelin, and an unknown phospholipid component. Changes in the relative amounts of the two major phospholipids were found when the early and late stages were compared. Two lipids found throughout development were identified as glycosylated dolichol phosphates, and they comprised between 1 and 3% of the total phospholipid fraction. Nineteen fatty acids were detected, and the fatty acid distribution for each lipid class at each stage was determined. Seven major fatty acids were common to each. These were: hexadecanoic, octadecanoic, oleic, linoleic, arachidonic, docosanoic, and docosahexaenoic.

Animals↗
PubMed1981

Tryptic modification of human serum low-density lipoprotein leads to altered rates of turnover and intravascular transformation in the guinea pig.

The metabolism of human serum low-density lipoprotein (LDL) and its trypsin-treated counterpart have been compared in the guinea pig in vivo. Removal of surface-exposed protein from the lipoprotein particle in this way resulted in significant modification of its metabolism in guinea pigs in vivo. Limited trypsinisation of LDL permitted removal of 20-25% of its protein moiety; trypsinised LDL was deficient in lysine and arginine residues (25-30% of each removed). The modified particle retained its basic structural features, such as internal molecular architecture, but displayed an elevated net negative surface charge and diminished immunological reactivity. Following intravascular injection of iodinated LDL (131I) and trypsinised LDL (125I) into the same animal, the two lipoproteins displayed biexponential decays; the rate constants for the plasma turnover of LDL and trypsinised LDL were significantly different (P less than 0.05), trypsinised LDL exhibiting a slower disappearance from the circulation. Density-gradient ultracentrifugation revealed marked elevation in the modal densities of both LDL and trypsinised LDL upon metabolism in vivo, although the rate of increase was greater for trypsinised LDL than LDL in each case (average increment 0.022 g/ml and 0.014 g/ml at 24 h respectively). The diminished plasma clearance of trypsinised LDL as compared to the native human and guinea pig LDL indicates that sites required for the cellular recognition and uptake of the LDL particle reside in its surface-exposed, trypsin-accessible protein. Furthermore, such protein appears to play a central role in regulating the intravascular processes by which the lipid content of LDL is diminished, and by which it is transformed to a particle of higher density.

Animals↗
PubMed1980

A comparative dielectric study of human serum low density lipoprotein before and after partial digestion by trypsin.

The relative permittivity of aqueous solutions of human serum low density lipoprotein (LDL) and partially trypsin digested lipoprotein (T-LDL) has been determined for various concentrations at 20 degrees C over the frequency range 0.15-100 MHz. Comparison of the dielectric dispersion curves for the digested lipoprotein with those for the native preparation revealed a larger low-frequency dielectric increment, which may be attributed to an increase in the number of counterions moving over the surface of the molecule. An explanation of this observation is an elevation of 70% in the net negative charge on the surface of the trypsin-treated particle as compared to its native counterpart.

Electrochemistry↗