Search Results - (Author, Cooperation:D. Morgan)

2011-10-25

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Aspartic Acid/genetics/*metabolism ; Electric Conductivity ; Histidine/genetics ; Humans ; Ion Channel Gating/drug effects/*genetics ; Ion Channels/*chemistry/genetics/*metabolism ; Isotonic Solutions/pharmacology ; Lysine/genetics ; Mutant Proteins/chemistry/genetics/metabolism ; Mutation/genetics ; Open Reading Frames/genetics ; Osmolar Concentration ; Permeability/drug effects ; *Protons ; Substrate Specificity/drug effects ; Sucrose/pharmacology

2012-02-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Charities/*economics ; Fund Raising/*economics ; *Research Support as Topic ; Science/*economics

2014-09-19

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Africa ; Aggression/*physiology/*psychology ; Animals ; Animals, Wild/physiology/psychology ; Behavior, Animal/*physiology ; Female ; Food ; *Human Activities ; Humans ; Male ; *Models, Biological ; *Pan paniscus/physiology/psychology ; *Pan troglodytes/physiology/psychology ; Population Density ; Sexual Behavior, Animal/physiology

1572-9699

Protein profiles ; Campylobacter pylori ; computer analysis ; electrophoresis

Springer Online Journal Archives 1860-2000

Biology

Abstract A total of 21 clinical isolates of Campylobacter pylori from Peru and the United Kingdom and two reference strains (from Australia), including the type strain (NCTC 11637T), were characterized by high resolution one-dimensional SDS-polyacrylamide gel electrophoresis of cellular proteins. The protein patterns contained more than 40 discrete bands and the approximate molecular weights of the major bands were 22, 27, 46, 57, 60, 65 and 93 kD. The total patterns were used as the basis of numerical analysis. Most strains were clustered in four phenons at 91% similarity with the exception of six ungrouped strains. Overall similarity was high with all strains linked in the phenogram at ≥81%. Variation among strains was attributable principally to qualitative and quantitative band differences in the 47 to 56 kD (hypervariable) region of the C. pylori protein profile. From the analysis, ten different electropherotypes (EP-types) were identified. We demonstrated that differences were detectable among isolates from widely separated geographical locations as well as from the same location, although multiple isolates from two Peruvian patients had the same electropherotype. Our results indicate that determination of protein profiles provides the basis of a reproducible method for characterization of C. pylori isolates.

Electronic Resource

2018-06-08

BMJ Publishing Group

0017-5749

1468-3288

Medicine

Gut

2018-07-21

The American Society for Biochemistry and Molecular Biology (ASBMB)

0021-9258

1083-351X

Biology

Chemistry and Pharmacology

2018-04-26

American Association for the Advancement of Science (AAAS)

2375-2548

Natural Sciences in General

2018-10-19

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Ecology

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Objective To determine the longitudinal changes in the incidence of bacterial vaginosis in pregnancy.Design A prospective study of women during pregnancy.Setting A District General Hospital in North-West London.Subject Seven hundred and eighteen pregnant women attending antenatal clinics. At their first attendance and subsequently, Gram-stained vaginal smears were examined and Mycoplasma hominis and Gardnerella vaginalis were sought by culture.Results Initially, 87 (12%) women had bacterial vaginosis diagnosed on Gram-stained reading of the vaginal smears. Examination of further smears, obtained from 176 women at 36 weeks of gestation, showed that those whose vaginal flora was normal initially, and who went to term, rarely developed vaginosis (three of 127, 2.4%). Samples were obtained at 36 weeks gestation from 32 women who had bacterial vaginosis initially, and went to term. In almost 50% (15 of 32) of these a normal lactobacillus-dominated flora had regenerated. Thirty-five women (5%) had initial vaginal smears graded as intermediate. From this group, six of the 17 (35%) women from whom samples were obtained at 36 weeks gestation still had flora of an intermediate pattern; 10 (59%) now had normal flora and only one (6%) had developed bacterial vaginosis. Women with bacterial vaginosis were more likely to be culture-positive for M. hominis than those with normal flora (34/78 versus 10/563, odds ratio 42.73 (18.9 to 102.3) P 〈 0.001), or to be culture-positive for G. vaginalis than those with normal flora (35/78 versus 21/563, odds ratio 21.0 (10.75 to 41.2) P 〈 0.001).Conclusion Pregnant women do not commonly develop bacterial vaginosis after 16 weeks gestation, and if present, it remits spontaneously in approximately half of those who reach term. As bacterial vaginosis is associated with increased rates of second trimester miscarriage and preterm delivery, any treatment aimed at its eradication in pregnancy should be given no later than the beginning of the second trimester of pregnancy.

Electronic Resource

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Objective To determine whether Gram-stained smears obtained from blind vaginal swabs could be used reliably for the assessment of the vaginal flora.Design A prospective, blind comparative study.Setting The antenatal clinic of a district general hospital.Participants Eighty-eight women examined and screened for the presence of bacterial vaginosis during their first antenatal clinic visit. Two smears were obtained for each woman, the first prepared from a vaginal swab taken blindly and the second at speculum examination. The smears were Gram-stained and classified according to the Nugent score: Grade 1 (normal), Grade 2 (intermediate), Grade 3 (bacterial vaginosis).Results Eight of the 88 pregnant women were identified as having bacterial vaginosis on the basis of the smear taken at speculum examination, and these were correctly identified as having bacterial vaginosis by smears prepared from the blindly taken swab. This gives the blind vaginal swab technique for detecting bacterial vaginosis a sensitivity and specificity of 100% when compared with swabbing at speculum examination. The flora of two women were graded as intermediate, and of 75 as normal by both techniques. Only in three cases was there a disparity between the two techniques, a difference that was not statistically significant (kappa = 0.8546,95% CI 0.6945 to 1.0).Conclusions Vaginal smears prepared from correctly taken blind vaginal swabs can be used to assess the vaginal flora and screen for bacterial vaginosis. This method could be used in epidemiological studies of bacterial vaginosis in the general population and for screening antenatal populations for abnormal vaginal flora.

Electronic Resource

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Summary. Serum polyamine oxidase activity was determined in 38 women admitted to the Maternity Department of Szombathely, Hungary, with clinical signs of threatened abortion between 11 and 22 weeks gestation and who aborted spontaneously with 48 h of admission. Serum polyamine oxidase activity was found to be significantly lower in these women compared with that in women having normal pregnancies of the same gestational age. The higher polyamine oxidase levels which were found in five women who aborted during oxytocin infusion probably resulted from increased contractions expelling enzyme-rich blood from the intervillous space into the maternal circulation. Present evidence is insufficient to explain the full clinical significance of these findings.

Electronic Resource

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Polyamine oxidase activity was measured in different compartments of the feto-maternal unit by a radiochemical method. The activity in the retroplacental serum (mainly of intervillous origin) was 20 to 30 times higher than in maternal uterine or peripheral venous blood sera. No activity was found in the fetal cord blood sera. The enzyme level in the maternal peripheral sera fell to undetectable levels within 72 hours post partum. Preliminary data indicate that the enzyme might be produced by the decidua rather than by the placenta. It is suggested that the enzyme may constitute an important part of a supposed local immunological barrier formed at the placental bed to help to protect the fetal allograft from maternal immune rejection through a local suppressive effect on maternal cellular immunity.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Recent publications dealing with the efficiency of utilization of dietary energy by ruminants suggest that metabolizable- and net-energy values may be calculated with reasonable precision from digestible-energy values. Use has been made here of existing data to estimate the metabolizable-energy (M. E.) and net-energy values for maintenance and fattening (N. E.m and N. E.f) of 5 samples of barn-dried hay of known in vivo digestibility, firstly to provide such figures for good quality barn-dried hays and, secondly, to illustrate a method of estimating energy values for hays that might be useful for routine advisory purposes.

Electronic Resource

1365-2494

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Four sheep in a 4 × 4 Latin Square experiment were offered ad libitum grass meal pellets alone or supplemented with lactic acid at 600, 800 or 1000 mmol per kg dry matter (DM) intake, either mixed into the feed or continuously infused intraruminally for 6-d periods. When added to the feed lactic acid did not significantly affect DM intake but when infused intraruminally it significantly reduced DM intake especially at the highest rate of infusion.In a second 4 × 4 Latin Square experiment, four sheep were offered ad libitum grass meal pellets alone or supplemented with lactic acid mixed into the pellets at 900, 1200 and 1500 mmol per kg DM for 15-d periods. There was a small reduction in intake on the three lactic acid treatments but this was not significant.In a third experiment the effects of intraruminal infusion with lactic acid was studied further with four sheep which received infusions of lactic acid at a fixed daily rate of 40 mmol per kg W−0·75 per d or of an equal volume of distilled water for 3-d periods while being offered grass meal pellets ad libitum. Infusion with lactic acid resulted in reduced DM intake but the effect was less consistent than in Experiment 1.In all three experiments lactic acid supplementation had little effect on the pH and total volatile fatty acid concentration of rumen

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The effects of growth temperature and subsequent annealing temperatures on the electrical properties of the low temperature (LT) grown GaAs have been investigated. It was found that the resistivity of the as-grown LT-GaAs layer increased with increasing growth temperature, but was accompanied by a reduction of breakdown voltage over the same temperature range. Thermal annealing of the samples caused the resistivity to rise exponentially with increasing annealing temperature TA, giving an activation energy of EA=2.1 eV. The transport of the LT-GaAs layers grown at Tg≤250 °C was found to be dominated by hopping conduction in the entire measurement temperature range (100–300 K), but following annealing at TA(approximately-greater-than)500 °C, the resistivity-temperature dependence gave an activation energy of ∼0.7 eV. The breakdown voltage VBD, for as-grown LT-GaAs was enhanced on lowering the measurement temperature, but conversely, decreased over the same temperature range following annealing at TA(approximately-greater-than)500 °C. The hopping conduction between arsenic defects, or arsenic clusters in annealed samples, is believed to be responsible for the observed electrical breakdown properties. Since the resistivities of the as-grown LT-GaAs layers are dependent, solely, on the excess arsenic, which in turn depends on the growth temperature, then the resistivities obtained can be used as a measure of the growth temperature. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

This paper presents a study of the microwave impedance of GaAs-AlxGa1−xAs resonant tunneling heterostructures. An equivalent-circuit model is proposed that accounts for the frequency variation of the measured impedance and whose elements correspond to physical phenomena believed to be present in the device. Empirical formulas are obtained which can be used to calculate the values of the equivalent-circuit elements from the structural parameters and the dc current-voltage characteristics of the device.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A technique using cavity perturbation of a cooled sapphire disk resonator has been developed to measure the surface impedance Zs=Rs+iXs of high-temperature superconducting thin films. The resonator is excited in the TE011 mode at 14.4 GHz and induces a-b plane screening currents in the sample. The resonator and its enclosure are maintained at 4.2 K while the sample is heated independently on a movable sapphire rod. The thermal isolation of the sample and resonator leaves the measurement virtually free of systematic error and permits the use of a superconducting niobium shield. The combination of low dielectric loss sapphire and a superconducting enclosure results in typical unloaded quality factors (Q) of several million. The ability to move the sample makes the sensitivity variable, allowing surface resistance values from 5 μΩ to several Ω to be measured. Background loss can also be accurately determined at the time of experiment by withdrawing the sample from the influence of the resonator. In addition, sensitive measurements of the penetration depth can be made by spring-loading the film onto quartz spheres glued to the resonator surface; this technique is shown to be free of systematic error up to a temperature of 60 K. © 1997 American Institute of Physics.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A cavity perturbation technique using split-ring resonators has been developed for measuring the surface resistance of metals in the frequency range 0.3–5.0 GHz. The system is designed particularly for measurements of films and crystals of high-Tc oxide superconductors. The small size of split-ring resonators in this frequency range makes them useful for measuring crystals with areas as small as 0.1 mm2. The measurement geometry is favorable for the study of films because the sample screens its substrate from the microwave fields. The resonator temperature can be kept fixed at 4.2 or 1.2 K for sample temperatures as high as 120 K and this thermal isolation from the sample allows the use of a superconducting split-ring resonator. An unloaded Q of 1.2×106 has been achieved with a superconducting resonator at 1.78 GHz and this makes it sensitive enough to detect surface resistances of the order of a few μΩ. This resonator has been used to measure the surface resistance (25 μΩ/(D'Alembertian)) of a 1-mm2 crystal of Bi2Sr2CaCu2O8.

Electronic Resource