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Biomedical subjects

S B Chin

Publications and source records attributed to S B Chin.

8 recordsLinked to original sources
PubMed2006

Investigation of the functional three-dimensional anatomy of the human cystic duct: a single helix?

Clinical research into the formation of gallstones has indicated that the anatomy of the cystic duct is one of a number of factors contributing to the formation of gallstones. The cystic duct allows low-viscosity hepatic bile to enter the gallbladder under low pressure and the expulsion of a more viscous gallbladder bile, but little is known about this transport mechanism and the effect of anatomical variations in structure. This article describes the variation in geometry of the cystic duct, obtained from acrylic resin casts of the neck and first part of the cystic duct in gallbladders removed for gallstone disease and obtained from patients undergoing partial hepatectomy for metastatic disease. The data obtained allowed us to formulate a number of standard terms for describing cystic duct morphology and demonstrate that the term "spiral valve" is only partially correct when describing the duct anatomy. In over half of the casts, spiraling was not the dominant feature of the cystic duct. Additionally, the term valve implies active resistance to flow in one direction, whereas the internal baffles of the cystic duct would serve to regulate bile flow in both directions. These data are useful for realistic 3D modeling of fluid-structure interactions of the flow of bile in the human cystic duct.

Bile Ducts↗
PubMed2004

The flow of bile in the human cystic duct.

Clinical studies suggest that the flow of bile in the biliary system may be a contributing factor in the pathogenesis of cholelithiasis, but little is known about its transport mechanism. This paper reports a numerical study of steady flow in human cystic duct models. In order to obtain parametric data on the effects of various anatomical features in the cystic duct, idealised models were constructed, first with staggered baffles in a channel to represent the valves of Heister and lumen. The qualitative consistency of these findings are validated by modelling two of the real cystic ducts obtained from operative cholangiograms. Three-dimensional (3D) models were also constructed to further verify the two-dimensional (2D) results. It was found that the most significant geometric parameter affecting resistance is the baffle clearance (lumen size), followed by the number of baffles (number of folds in the valves of Heister), whilst the least significant ones are the curvature of the cystic duct and the angle between the neck and the gallbladder. The study presented here forms part of a larger project to understand the functions of the human cystic duct, especially the influence of its various anatomical structures on the resistance to bile flow, so that it may aid the assessment of the risk of stone formation in the gallbladder.

Bile↗
PubMed1992

Consonant clusters in disordered speech: constraints and correspondence patterns.

Comparison of patterns of cluster realization from 47 children ranging in age from 3;4 to 6;8 with functional (non-organic) speech disorders with those reported in the literature for normal acquisition reveals that these patterns are essentially the same for both groups. Using a two-level generative phonology for children's independent systems, further analysis of cluster realizations by means of feature geometry and underspecification theory reveals that there are systematic and principled relationships between adult representations of clusters and children's underlying representations and between children's underlying representations and their phonetic representations. With special emphasis on coalescence phenomena, it is suggested that the apparent diversity in children's cluster realizations can be reduced to four constraints on the form of underlying and phonetic representations.

Child↗
PubMed1992

Variables contributing to anticipatory nausea and vomiting in cancer chemotherapy.

Forty cancer patients receiving parenteral chemotherapy were assessed for characteristics associated with the development of anticipatory nausea and vomiting (ANV). The patients who developed ANV were more likely to have increased pretreatment anxiety (p less than 0.05), greater posttreatment dizziness/lightheadedness (p less than 0.01), more severe postchemotherapy vomiting (p less than 0.01), and a delayed onset of postchemotherapy nausea and vomiting (PCNV) compared to the patients who developed neither ANV nor PCNV. However, when patients who did not develop PCNV were excluded from the analysis, the difference between the ANV and non-ANV patients remained significant only for postchemotherapy dizziness/lightheadedness (p less than 0.05). In an attempt to identify a group of variables that better predict the development of ANV, we analyzed the data for combinations of variables. Two indices were found to correctly classify ANV and non-ANV patients 71% of the time (p less than 0.05). Index A refers to the presence of at least two of the following variables, pretreatment anxiety, posttreatment dizziness/lightheadedness, and latency of PCNV. Index B refers to the presence of at least two of the following variables: pretreatment anxiety, severity of nausea, and severity of vomiting. The identification of characteristics associated with the development of ANV could lead to new intervention strategies.

Affect↗
PubMed1990

Generalization to conversational speech.

Although changes in children's phonological systems due to treatment have been documented in single-word testing, changes in conversational speech are less well known. Single-word and conversation samples were analyzed for 10 phonologically disordered children, before and after treatment and 3 months later. Results suggest that for most of the children, there were system changes in both single words and in conversational speech. It appears that many phonologically disordered children are able to extend their correct production to conversation without direct treatment on spontaneous speech.

Analysis of Variance↗
PubMed1990

Some constraints on functionally disordered phonologies: phonetic inventories and phonotactics.

The phonological systems of 40 functional misarticulators, ages 40 to 80 months were examined in terms of the nature and variation of phonetic inventories and phonotactic constraints. It was found that these properties of disordered systems were governed by severe constraints that yielded a typological characterization of such systems along with associated implicational laws. The principles governing disordered systems were also found to parallel closely the principles governing normal first language acquisition. The evidence suggests that at least these properties of disordered systems represent delays in the normal acquisition process and are not otherwise deviant. The assessment and treatment of functional disorders along with the projection of learning patterns can thus appeal to principles governing such phonological systems.

Articulation Disorders↗
PubMedDate not supplied

Relationships among types of speech intelligibility in pediatric users of cochlear implants.

UNLABELLED: Twenty pediatric users of cochlear implants were administered three tests of speech intelligibility: (1) a test of contrast perception intelligibility, (2) a test of contrast production intelligibility, and (3) a test of production sentence intelligibility. Sixty adults with normal hearing served as listener judges for the two speech production tasks, and percent correct scores were generated for each of the three tasks. Correlational analyses showed significant correlations among overall scores for the three tasks. However, scores for individual feature classes from the contrast perception task were not correlated with their corresponding contrast production feature class scores, and only some of the feature class scores were correlated significantly with sentence intelligibility. We conclude that although these three types of intelligibility are related at a gross level, relationships are more tenuous at finer levels of analysis, suggesting that the separate skills may need to be addressed separately in remediation. EDUCATIONAL OBJECTIVES: As a result of this activity, the participant will be able to differentiate various methods for assessing speech intelligibility and describe the relationships among different types of speech intelligibility in pediatric users of cochlear implants.

Child↗