Biomedical subjects

W Richard Chegwidden

Publications and source records attributed to W Richard Chegwidden.

3 recordsLinked to original sources

PubMed2006

A problem-based learning pathway for medical students: improving the process through action research.

INTRODUCTION: Problem-based learning (PBL) is student-centred, self-directed and collaborative. In medical education it is based on clinical cases and is widely considered to facilitate the development of key professional competencies. Whilst PBL is extensively employed in medical schools worldwide, Lake Erie College of Osteopathic Medicine is one of very few schools that offer it to pre-clinical students as a major pathway of study. We have identified several problems associated with implementation of the programme and attempted to provide solutions with 3 new learning tools. In this study we use action research to evaluate the success of our strategy. METHODS: We examined the students' perception of the effectiveness of case-based formative assessment, case-based "question and answer" workshops, and reviews of annotated examinations as learning tools, using a 5-point Likert scale questionnaire. RESULTS: A majority of both first- and second-year students perceived all 3 learning tools to be helpful. In general, the most positive responses were received from second-year students. First-year students evaluated casebased formative assessments more positively when they were about to take examinations. CONCLUSIONS: Case-based formative assessments, case-based workshops and reviews of annotated examinations were perceived as helpful learning tools by both first- and second-year medical students in PBL learning pathways.

Education, Medical↗

PubMed2004

A new synthesis of difluoromethanesulfonamides--a novel pharmacophore for carbonic anhydrase inhibition.

Preparation of the key intermediate carboxydifluoromethanesulfonamide provides direct synthetic access to a wide range of novel difluoromethanesulfonamides, including the acetazolamide analogue (2-ethanoylamino-1,3,4-thiadiazol-5-yl)-difluoromethanesulfonamide. Their water solubility and stability, ether partition coefficient, pK(a) and submicromolar dissociation constants for human carbonic anhydrase isozyme II (HCA II) make them promising candidates for topical glaucoma therapy.

Carbonic Anhydrase II↗

PubMed2002

Crystal structure of a zinc-activated variant of human carbonic anhydrase I, CA I Michigan 1: evidence for a second zinc binding site involving arginine coordination.

The human genetic variant carbonic anhydrase I (CA I) Michigan 1 results from a single point mutation that changes His 67 to Arg in a critical region of the active site. This variant of the zinc metalloenzyme appears to be unique in that it possesses an esterase activity that is specifically enhanced by added free zinc ions. We have determined the three-dimensional structure of human CA I Michigan 1 by X-ray crystallography to a resolution of 2.6 A. In the absence of added zinc ions, the mutated residue, Arg 67, points out of the active site, hydrogen bonding with the carboxylate of Asn 69. This contrasts with the orientation of His 67, in the native isozyme, which points into the active site. The orientations of His 94, His 96, and His 119, that coordinate the catalytic zinc ion, and of the catalytically critical Thr 199-Glu 106 hydrogen bonding system, are largely unchanged in the mutant. The structure of an enzyme adduct with a second zinc bound was determined to a resolution of 2.0 A. The second zinc ion is coordinated to His 64, His 200, and Arg 67. This arginine residue reverses its orientation on zinc binding and turns into the active site. The residues at these three positions have been implicated in determining the specific kinetic properties of native CA I. This is, to our knowledge, the first example of a zinc ion coordinating with an arginine residue in a Zn(II) enzyme.

Arginine↗