Search Results - (Author, Cooperation:M. S. Thomas)

2011-10-21

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Adolescent ; Brain/anatomy & histology/*growth & development/*physiology ; Child ; Cross-Sectional Studies ; Functional Neuroimaging ; Health ; Humans ; Intelligence/*physiology ; Intelligence Tests ; Magnetic Resonance Imaging ; Speech/physiology ; Verbal Behavior/*physiology ; Verbal Learning/physiology

2012-06-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Adolescent ; Brain/anatomy & histology/*physiology ; Humans ; Intelligence/*physiology ; Intelligence Tests ; Verbal Learning/*physiology

2018-01-05

Genetics Society of America (GSA)

0016-6731

Biology

2011-01-29

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

*Agriculture/methods ; *Climate Change ; Conservation of Natural Resources ; Diet ; *Food Supply ; Humans ; *International Cooperation ; Policy ; Politics ; Research ; United Nations

2015-12-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

2015-09-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Ecology/statistics & numerical data ; Ecosystem ; Forestry/statistics & numerical data ; *Forests ; *Geographic Mapping ; Population Density ; Reproducibility of Results ; Trees/*growth & development

2011-10-21

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

*Acclimatization ; *Climate Change ; Disasters ; Emigration and Immigration/*statistics & numerical data/*trends ; *Environment ; Floods ; Humans ; Policy Making ; Politics ; Poverty ; Risk ; Socioeconomic Factors ; Urban Population

2018-10-25

American Physical Society (APS)

1539-3755

1550-2376

Physics

Plasma Physics

1365-2958

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

The rpoA341 (phs) mutation of Escherichia coli results in decreased expression of several positively regulated operons and has been mapped to within or very near the rpoA gene encoding the α subunit of RNA polymerase. We have shown that plasmid-directed synthesis of the wild-type α subunit can complement the defective phenotypes associated with this mutation consistent with its proposed location within rpoA. This mutation was mapped by marker rescue to within a 182bp region near the 3’end of rpoA and was subsequently transferred to a plasmid by recombination in vivo. DNA sequence analysis revealed that the RpoA341 phenotype was the result of the substitution of lysine 271 by glutamate within the α polypeptide. We discuss this result in relation to our current understanding of the functional organization of the α subunit.

Electronic Resource

1432-1440

Case method ; Curriculum ; Undergraduate education ; McMaster philosophy ; Teaching methods ; Problem-based learning

Springer Online Journal Archives 1860-2000

Medicine

Summary Students of three different levels and the chairman of the MD-Program evaluated the educational system of McMaster University, Canada, using the six criteria of the case method as defined by Renschler. This analysis provided a very differentiated evaluation of the McMaster curriculum, demonstrating a systematic progress of learning methods from the second to the last phase. The instrument showed differences in the ratings of the demonstrative lectures between the chairman and the students. Free access to patients and responsibility, gradually growing during the 3-year program, are important features of the educational system. The problem-based system provides a unique integration of acquiring theoretical knowledge in the basic sciences through clinical problem solving which was highly rated in all analysed phases. Ratings given by the interviewed students for evaluation of documented work were lower than expected by the chairman and the authors. The results are discussed in relationship to the McMaster Philosophy and to the conditions of studying medicine in America and in Germany.

Electronic Resource

1432-1041

cardioselectivity ; beta-adrenoceptor blockers ; diacetolol ; acebutolol ; metoprolol ; propranolol ; healthy volunteers

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Medicine

Summary 1. The beta-adrenergic selectivity of diacetolol, the major metabolite of acebutolol, has been compared with that of acebutolol, metoprolol and propranolol in 11 normal subjects. 2. Bronchial and cardiac beta-adrenoceptor blockade were assessed on separate occasions after diacetolol 600 mg, acebutolol 400 mg, metoprolol 200 mg, propranolol 80 mg and placebo. 3. Bronchial beta-adrenoceptor blockade was assessed as the displacement of the bronchodilator dose response curve to inhaled isoprenaline after each beta blocking drug compared to placebo and expressed as the dose ratio. Bronchodilatation was measured as change in specific airway conductance (sGaw) in the body plethysmograph. Cardiac beta-adrenoceptor blockade was assessed as the percentage reduction in exercise heart rate during the 5th minute of exercise at 70% of the subject's maximum work rate. 4. There was a significant reduction in exercise heart rate with all 4 beta-blocking drugs when compared with placebo, 22% for diacetolol, 24% for acebutolol, 25% for propranolol and 28% for metoprolol. The reduction with metoprolol was significantly greater than the reduction with the other three beta-adrenoceptor antagonists. 5. Mean dose ratios for the airway isoprenaline dose response curves after each of the 4 beta-blocking drugs were 2.4 for diacetolol, 2.7 for metoprolol, 8 for acebutolol and 72 for propranolol. The difference between diacetolol and metoprolol was not significant. 6. Thus diacetolol appears to be more cardioselective than acebutolol and both are more cardioselective than propranolol in man. Metoprolol is probably more cardioselective than diacetolol though interpretation of the differences in exercise heart rate is complicated by the fact that diacetolol has some intrinsic sympathomimetic activity.

Electronic Resource

1617-4623

Key words RNA polymerase α subunit  ;  Phage λ development  ;  Phage λ promoters  ;  Positive control of transcription  ;  CII activator

Springer Online Journal Archives 1860-2000

Biology

Abstract The C-terminus of the α subunit of Escherichia coli RNA polymerase is known to function in transcriptional activation at certain promoters. This region was previously shown to be necessary for full activation of the p E promoter by the phage λ CII protein in vitro. In this work we investigated the inability of phage λ to follow the lysogenic pathway in cells carrying the point mutation rpoA341 (a change of lysine 271 to glutamic acid). We found that neither overexpression of the cII gene nor stabilisation of the CII protein by the can1 mutation or by cIII gene overexpression was able to suppress the block in lysogenisation. In contrast, the λcin1 phage, which carries a CII-independent promoter for the expression of the cI gene, was able to efficiently lysogenise the rpoA341 mutant strain. Furthermore, the rpoA341 mutation prevented the activation of p E-lacZ and p I-lacZ transcriptional fusions by CII. Therefore we conclude that transcriptional activation by the cII gene product is abolished by the rpoA341 mutation, most probably due to impaired interaction between the CII activator and mutant RNA polymerase. The inability of RNA polymerase to respond to CII results in the impairment of lysogenisation of the rpoA341 mutant by phage λ.

Electronic Resource

0006-3592

Chemistry ; Biochemistry and Biotechnology

Wiley InterScience Backfile Collection 1832-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Lactate dehydrogenase (LDH) was covalently attached to an impervious nylon surface by an improved technique. The procedure allowed the kinetics of the rotating enzyme disk reactor to be successfully explored. This enzyme-disk configuration has potential applications in assays for lactic acid or pyruvic acid in fluids of biological importance (e.g., urine). In order to evaluate and understand the physics and chemistry underlying the kinetics of the heterogeneous biocatalyst, a mathematical model based on the von Karman-Levich theories of rotating electrodes, was developed. It applied well to LDH attached to a disk, under variable NADH concentrations and fixed pyruvic acid. The new theory, leads to the conclusion that the apparent Michaelis constant Km(app), varies linearly with f-1/2, where f is the speed of rotation of the disk. Extrapolation of f-1/2 to zero gives the Michaelis-Menten constant, Km, corresponding to the diffusion-free behavior. With immobilized LDH, the diffusion-free Km for NADH obtained at 25°C, in phosphate buffer (pH 7.5) using the extrapolation method was 84 μM. This value was in good agreement with the previously published value of 87 μM, obtained with LDH attached to the inner surface of a nylon tubing. However, when compared to the Km for a free enzyme system, the 84 μM was about nine times larger, indicating an inherent reduction in the activity of the bound LDH. Since, at extrapolated infinite rotation speeds, diffusion effects were assumed eliminated, the drop in the activity was thought to be due to sterric hinderances imposed on the substrate NADH as a result of having LDH bound to another polymer.

7 Ill.

Electronic Resource

0021-9304

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Medicine

Technology

A rapid mixing and sampling technique was used to study the permeability characteristics of semipermeable aqueous microcapsules (artificial cells). Urea, creatine, creatinine, uric acid, glucose, sucrose, and salicylic acid equilibrated rapidly across nylon microcapsules of 207 μ diameter (e.g., T 1/2 for urea of 3.4 sec). From these results the permeability constants were calculated (e.g., P for urea of 2 × 10-4 cm/sec). Very much the same permeability constants were found for collodion microcapsules. The equivalent pore radius of the membrane of the nylon microcapsules were estimated to be 18 A.

5 Ill.

Electronic Resource