PubMed Health⌕ Search

Biomedical subjects

D Barton

Publications and source records attributed to D Barton.

At least 73 records · Page 4Linked to original sources
PubMed1978

Design of a specific oxidant for phenols.

Selective ortho-substitution of phenols can be secured, in principle, by attachment of the substituting reagent to the phenolic hydroxy group and subsequent rearrangement of this derivative by a cyclic mechanism into the orthoposition. So far, only one example of this principle (the Claisen rearrangement) is well established. For ortho-hydroxylation, a phenolic ester of selenium(IV) should have the desired properties. Diphenylseleninic anhydride, PhSE(=0)0.Sec(=0)Ph, has proved has proved to be the new reagent for the application of this mechanism. Several phenols, including models of the phenolic ring A of tetracycline, gave o-hydroxydienones, with quinones and phenylselenated species as by-products, when treated with diphenylseleninic anhydride. When the phenols were converted into their corresponding anions before treatment with the anhydridide, the o-hydroxydienones were obtained in good yield free from other products arising from reaction at the para position. When phenols were added to a warm solution of diphenylseleninic anhydride, they were oxidized to the o-quinones even when the phenols were not substituted in para position.

Anhydrides↗
PubMed1975

Goals of medical student psychiatric education.

In this article the authors present a comprehensive statement of the goals of medical student psychiatric education. The focus is on content rather than on the process of teaching or of curriculum design. Many of the areas of learning are likely either to be taught by nonpsychiatric instructors or to be not specifically programmable into a curriculum. The approach of focusing on the desired competence in terms of knowledge, skills, and attitudes can result in these goals and their subsequent modifications serving as a benchmark for assessment of the adequacy of a particular program.

Adaptation, Psychological↗
PubMedDate not supplied

Ret-proto-oncogene analysis in medullary thyroid carcinoma.

INTRODUCTION: Medullary carcinoma of the thyroid (MTC) is a rare tumour which occurs in both sporadic and hereditary forms. Mutations of the RET proto-oncogene have been identified in hereditary forms. The aim of our study was to confirm or exclude familial disease by examining for germline mutations in the RET proto-oncogene in patients with medullary thyroid carcinoma. METHODS: Nine patients with medullary thyroid carcinoma and 4 of their children were studied. Peripheral blood was used to examine for mutations in the RET proto-oncogene. When this was not available, archival thyroid tissue was used. RESULTS: Seven patients had clinically sporadic tumours confirmed by mutational analysis of RET. Four children were at risk of being carriers of a mutated gene, as their fathers had histologically proven MTC and had tested positive for the mutation at codon 618 on exon 10 of the RET proto-oncogene. Three of these children carried the 618 mutation. To date, 2 have had a prophylactic thyroidectomy, the pathology of which revealed C-cell hyperplasia. One child had familial disease excluded by mutational analysis. One patient had a clinical diagnosis of MEN2B confirmed by detection of the 918 mutation on exon 16 of the RET proto-oncogene. CONCLUSIONS: RET proto-oncogene analysis is a reliable method of differentiating familial from sporadic MTC. Mutational information determines which family members of affected kindreds are at risk of developing the disease and can be used to affect clinical management.

Adolescent↗
PubMedDate not supplied

Primary torsion dystonia due to the Tor1A GAG deletion in an Irish family.

BACKGROUND: Early, limb-onset primary torsion dystonia (PTD) is commonly due to a trinucleotide GAG deletion in the TOR1A (DYT1) gene on chromosome 9q34. The majority of carriers of this mutation conform to a characteristic phenotype that is similar in different ethnic populations. AIM: To describe the clinical features of affected members of a large Irish family with PTD due to the TOR1A deletion. METHODS: Fourteen consenting family members from three generations were examined according to a standardised protocol. RESULTS: Five affected individuals were identified. Two had a somewhat atypical phenotype with focal and segmental upper-limb dystonia without further progression. CONCLUSION: The authors describe the clinical features of PTD due to the TOR1A GAG deletion in an Irish family illustrating the presence of intrafamilial phenotypic variability.

Adult↗
PubMedDate not supplied

The Wilms tumor suppressor gene wt1 is required for development of the spleen.

The Wilms tumor suppressor gene WT1 (wt1 in mouse) is unique among tumor suppressors because, in addition to its involvement in cancer [1] [2] and various other diseases [3] [4] [5] [6], it has an essential role in the development of certain organs. This is revealed by the phenotype of mice with inactivated wt1 alleles [7]. These animals exhibit a complete failure of kidney and gonad development as well as abnormalities of the heart and mesothelial structures. On a C57BL/6 genetic background, wt1(-/-) animals die between day 13.5 (E13.5) and 15.5 (E15.5) of embryonic development [7]. We report here that crossing of the wt1 mutation onto different mouse backgrounds delayed embryonic lethality until birth. In wt1(-/-) mice on these different genetic backgrounds, we observed a dramatic failure of spleen development, in addition to the well characterized phenotypic abnormalities. The spleen anlage formed at around E12 to E13 and involuted by the E15 stage, before the invasion of hematopoietic cells. The absence of proper spleen development in these wt1(-/-) embryos correlated with enhanced apoptosis in the primordial spleen cells. The expression of hox11, a gene that also controls development of the spleen [8] [9], was not altered by the inactivation of wt1. In situ hybridization revealed that the two genes are regulated independently. These findings demonstrate that the penetrance of the wt1(-/-) phenotype depends on the existence of one or more modifier gene(s) and that wt1 plays a pivotal role in the development of the spleen, thereby extending its role in organogenesis.

Animals↗
PubMedDate not supplied

Assessment of a triage label system during a major incident exercise.

The Metag triage label system was assessed during a major incident exercise at an international airport. The exercise simulated a crash of a plane carrying 40 passengers within the airport boundaries. A secondary incident also was staged involving an explosion resulting in a fire with three victims injured. The exercise involved the airport, fire, police, ambulance, and medical services of three counties--Leicestershire, Derbyshire, and Nottinghamshire. Use of the labels enabled evaluation of the triage process, early medical intervention for victims, and completion of the cards.

Accidents, Aviation↗
PubMedDate not supplied

Comparison of acute hepatocellular proliferating cell nuclear antigen labeling indices and growth fractions, p34cdc2 kinases, and serum enzymes in carbon tetrachloride-treated rats.

We evaluated various biomarkers associated with cell proliferation immediately following insult with the classic hepatotoxicant carbon tetrachloride (CCl4). Rats were administered a single necrogenic dose of CCl4 and euthanized at either t = 4, 8, 12, 16, or 24 hr postdose. Parameters evaluated included the following: immunohistochemical detection of hepatocellular proliferating cell nuclear antigen labeling indices (PCNA-LIs; percentage of cells in S phase) and growth fractions (PCNA-GFs; percentage of cells in the cell cycle); PCNA and the cyclin-dependent kinase p34cdc2 (CDK) protein in S-9 fractions by Western blot and enzyme-linked immunosorbent assay (ELISA); and liver-related serum enzymes. An increase in PCNA-GF was observed at t = 4 hr, concomitant with elevations in CDK and PCNA protein (Western blot). PCNA-LIs were increased by t = 24 hr, as were CDK and PCNA by ELISA. Sorbitol dehydrogenase was the most sensitive enzyme, with increases observed at t = 4 hr. Our results indicate that PCNA-GF, CDK, and PCNA levels reflect hepatocellular regeneration as early as 4 hr following CCl4 insult. We conclude that these assays are early and sensitive indicators of acute hepatotoxicity that may be advantageous to evaluate in the early stages of exploratory studies.

Alanine Transaminase↗