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Biomedical subjects

A Munn

Publications and source records attributed to A Munn.

16 recordsLinked to original sources
PubMed2000

Processing coordinate structures.

Coordination often involves syntactically like categories. Based on the results of four reading time studies, it is argued here that the syntactic like-category restriction is not grammatical. Coordination of unlike categories can be just as acceptable as coordination of like categories. However, syntactically like category coordination is processed faster than coordination of unlike categories even when the two sentence types are judged to be fully acceptable. Further, parallelism of conjuncts facilitates processing regardless of whether it is parallelism in the category of the conjuncts (a property which the grammar might regulate) or parallelism in the internal structure of the conjuncts (a property which the grammar does not regulate, on anyone's view). Parallelism did not facilitate processing when the structure of a subject and object were manipulated, implying that parallelism effects are largely limited to the conjuncts of a coordinate structure and not due simply to the repetition of a phrase with a particular shape.

Cognition↗
PubMed1998

Double-agents and trace-deletion in agrammatism.

The Trace-Deletion Hypothesis (henceforth TDH; Grodzinsky 1986, 1995) states that syntactic traces are deleted in agrammatism and that whenever a trace is deleted, a default strategy is activated. The default strategy assigns the role of Agent to the first NP. In structures where a second NP receives the Agent role syntactically, the consequence is that the agrammatic representation contains two conflicting Agents for the same action. This is the mechanism that induces guessing and the random performance on comprehension tests that has often been observed for passives and certain other structures. In this paper, we isolate the default strategy of the TDH, using a sentence-picture matching task in which one of the pictures matches the meaning arrived at by the default strategy. Our results show that an agrammatic representation does not involve double-Agents, and thus the default strategy (and therefore the TDH) is refuted.

Adolescent↗
PubMed1997

A novel structural model for regulation of clathrin function.

The distinctive triskelion shape of clathrin allows assembly into polyhedral lattices during the process of clathrin-coated vesicle formation. We have used random and site-directed mutagenesis of the yeast clathrin heavy chain gene (CHC1) to characterize regions which determine Chc trimerization and binding to the clathrin light chain (Clc) subunit. Analysis of the mutants indicates that mutations in the trimerization domain at the triskelion vertex, as well as mutations in the adjacent leg domain, frequently influence Clc binding. Strikingly, one mutation in the trimerization domain enhances the association of Clc with Chc. Additional mutations in the trimerization domain, in combination with mutations in the adjacent leg domain, exhibit severe defects in Clc binding while maintaining near normal trimerization properties. The position of these trimerization domain mutations on one face of a putative alpha-helix defines a region on the trimer surface that interacts directly with Clc. These results suggest that Clc extends into the Chc trimerization domain from the adjacent leg, thereby bridging the two domains. On the basis of this conclusion, we propose a new model for the organization of the triskelion vertex which provides a structural basis for regulatory effects of Clc on clathrin function.

Amino Acid Sequence↗
PubMed1997

EH domain proteins Pan1p and End3p are components of a complex that plays a dual role in organization of the cortical actin cytoskeleton and endocytosis in Saccharomyces cerevisiae.

Several proteins from diverse organisms have been shown to share a region of sequence homology with the mammalian epidermal growth factor receptor tyrosine kinase substrate Eps15. Included in this new protein family, termed EH domain proteins, are two yeast proteins, Pan1p and End3p. We have shown previously that Pan1p is required for normal organization of the actin cytoskeleton and that it associates with the actin patches on the cell cortex. End3p has been shown by others to be an important factor in the process of endocytosis. End3p is also known to be required for the organization of the actin cytoskeleton. Here we report that Pan1p and End3p act as a complex in vivo. Using the pan1-4 mutant which we isolated and characterized previously, the END3 gene was identified as a suppressor of pan1-4 when overexpressed. Suppression of the pan1-4 mutation by multicopy END3 required the presence of the mutant Pan1p protein. Coimmunoprecipitation and two-hybrid protein interaction experiments indicated that Pan1p and End3p associate with each other. The localization of Pan1p to the cortical actin cytoskeleton became weakened in the end3 mutant at the permissive temperature and undetectable at the restrictive temperature, suggesting that End3p may be important for proper localization of Pan1p to the cortical actin cytoskeleton. The finding that the pan1-4 mutant was defective in endocytosis as severely as the end3 mutant under nonpermissive conditions supports the notion that the association between Pan1p and End3p is of physiological relevance. Together with results of earlier reports, these results provide strong evidence suggesting that Pan1p and End3p are the components of a complex that has essential functions in both the organization of cell membrane-associated actin cytoskeleton and the process of endocytosis.

Actins↗
PubMed1996

Actin-, myosin- and ubiquitin-dependent endocytosis.

Endocytosis is a general term that is used to describe the internalization of external and plasma membrane molecules into the cell interior. In fact, several different mechanisms exist for the internalization step of this process. In this review we emphasize the work on the actin-dependent pathways, in particular in the yeast Saccharomyces cerevisiae, because several components of the molecular machinery are identified. In this yeast, the analysis of endocytosis in various mutants reveals a requirement for actin, calmodulin, a type I myosin, as well as a number of other proteins that affect actin dynamics. Some of these proteins have homology to proteins in animal cells that are believed to be involved in endocytosis. In addition, the demonstration that ubiquitination of some cell surface molecules is required for their efficient internalization is described. We compare the actin, myosin and ubiquitin requirements for endocytosis with recent results found studying these processes using Dictyostelium discoideum and animal cells.

Actins↗
PubMed1987

Altered translation of the uncC gene coding for the epsilon subunit of the F1F0-ATPase of Escherichia coli.

The nucleotide sequence of the previously described uncC424 allele was determined and found to be the same as that of a wild-type uncC gene. However, a G----A change occurred 7 nucleotides upstream from the translation start codon, changing the putative Shine-Dalgarno sequence from GAGG to GAAG. Four revertant strains were examined. In one revertant, which had normal growth and membrane properties, a single base deletion had occurred to re-form the Shine-Dalgarno sequence GAGG 1 nucleotide closer to the translation start codon. A second revertant had a single base deletion in the preceding uncD gene, causing an extension of the beta subunit by 6 amino acids and an increase, presumably by translational coupling, in the amount of epsilon subunit. The third and fourth revertant strains were phenotypically similar and had either C----T or G----T changes 18 or 19 nucleotides, respectively, upstream from the translation start codon.

Base Sequence↗
PubMed1976

Control of carcinogenic hazards in industry.

Complete control of carcinogenic hazards in industry is an unrealistic concept. Industry, nevertheless, has a duty to give careful consideration to existing carcinogenic hazards, and to the possibility of new ones. Only well recognized hazards can be subjected to legislative control. Industry must take into account published experimental and epidemiological data, along with physical and chemical considerations related to specific agents, and, where necessary, introduce appropriate preventive measures.

Air Pollutants, Occupational↗
PubMedDate not supplied

Hyperosmolar non-ketotic hyperglycaemia.

Thorough assessment of the patient and good understanding of potential complications enhance patient care and safety. Correction of volume depletion and maintenance of a strict fluid balance chart is essential to avoid complications of congestive cardiac failure, cerebral or pulmonary oedema, renal failure and further dehydration. Careful monitoring of electrolytes and administration of supplements should be undertaken to prevent instability. Regular monitoring of blood glucose levels and careful insulin administration should be undertaken to prevent fluctuations in blood glucose levels. Any possible source of infection should be identified and treated as prescribed. Good basic nursing care for the patient and support and counselling for the patient and his family are essential components of holistic care.

Humans↗