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Biomedical subjects

C C Thomas

Publications and source records attributed to C C Thomas.

At least 19 recordsLinked to original sources
PubMed2006

Elastic instabilities of polymer solutions in cross-channel flow.

When polymer molecules pass near the hyperbolic point of a microchannel cross flow, they are strongly stretched. As the strain rate is varied at low Reynolds number (< 10(-2)), tracer and particle-tracking experiments show that molecular stretching produces two flow instabilities: one in which the velocity field becomes strongly asymmetric, and a second in which it fluctuates nonperiodically in time. The flow is strongly perturbed even far from the region of instability, and this phenomenon can be used to produce mixing.

Journal Article↗
PubMed2001

Crystal structure of the phosphatidylinositol 3,4-bisphosphate-binding pleckstrin homology (PH) domain of tandem PH-domain-containing protein 1 (TAPP1): molecular basis of lipid specificity.

Phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)] and its immediate breakdown product PtdIns(3,4)P(2) function as second messengers in growth factor- and insulin-induced signalling pathways. One of the ways that these 3-phosphoinositides are known to regulate downstream signalling events is by attracting proteins that possess specific PtdIns-binding pleckstrin homology (PH) domains to the plasma membrane. Many of these proteins, such as protein kinase B, phosphoinositide-dependent kinase 1 and the dual adaptor for phosphotyrosine and 3-phosphoinositides (DAPP1) interact with both PtdIns(3,4,5)P(3) and PtdIns(3,4)P(2) with similar affinity. Recently, a new PH-domain-containing protein, termed tandem PH-domain-containing protein (TAPP) 1, was described which is the first protein reported to bind PtdIns(3,4)P(2) specifically. Here we describe the crystal structure of the PtdIns(3,4)P(2)-binding PH domain of TAPP1 at 1.4 A (1 A=0.1 nm) resolution in complex with an ordered citrate molecule. The structure is similar to the known structure of the PH domain of DAPP1 around the D-3 and D-4 inositol-phosphate-binding sites. However, a glycine residue adjacent to the D-5 inositol-phosphate-binding site in DAPP1 is substituted for a larger alanine residue in TAPP1, which also induces a conformational change in the neighbouring residues. We show that mutation of this glycine to alanine in DAPP1 converts DAPP1 into a TAPP1-like PH domain that only interacts with PtdIns(3,4)P(2), whereas the alanine to glycine mutation in TAPP1 permits the TAPP1 PH domain to interact with PtdIns(3,4,5)P(3).

Adaptor Proteins, Signal Transducing↗
PubMed1999

Investment strength as a function of time and temperature.

OBJECTIVES: The purpose of this investigation was to evaluate and compare the compressive strength characteristics of selected investments and to determine if these change as a function of time and temperature after mixing. METHODS: Two phosphate-bonded investments and one gypsum-bonded investment were selected and 288 cylindrical specimens were fabricated (n = 9). Baseline compressive strength values were determined for each material at room temperature and compressive strength measurements were made for all materials at 700 degrees C, and at 872 degrees C only for phosphate-bonded investments. Each material was tested at 2, 6, 12, and 24 h after mixing. Specimens were heated at 15 degrees C/min and heat soaked for 5 min in a burnout oven at the applicable testing temperature. They were transferred to a preheated chamber on an Instron testing machine and subjected to a compressive load at a crosshead speed of 2 mm/min until failure. The resulting strength data are presented in MN/m2. RESULTS: The gypsum-bonded investment did not exhibit marked differences in strength as a function of either time or temperature. The phosphate-bonded investments, on the other hand, demonstrated considerable changes in compressive strength and differed in compressive strength characteristics at 700 degrees C and 872 degrees C respectively. CONCLUSIONS: At elevated temperatures, all materials approximated peak strength 2 h after initial mixing. At room temperature, the phosphate-bonded investments in this study were not significantly stronger than the gypsum-bonded investment material. However, they exhibited increased compressive strength as a function of time and temperature that was considerably higher than that exhibited by the gypsum-bonded investments.

Analysis of Variance↗
PubMed1994

A survey of trainees and recently accredited specialists in occupational medicine in the United Kingdom.

Information from a study group of doctors training or recently trained in occupational medicine was gathered using a self-administered questionnaire mailed to each subject's registered address. Of the 224 individuals identified from scrutiny of records held by the Faculty of Occupational Medicine, replies were received from 181 (81 per cent). Recruitment occurs in broadly equal proportions from general practice, general practice trainees, the hospital sector and the forces, with a wide diversity of experience among trainees. On average, trainees experience at least two industrial sectors during their training. There were disappointingly small numbers in part-time training.

Adult↗
PubMed1994

Detection of medullary carcinoma of the thyroid with I-131 MIBG.

Imaging with I-131 MIBG has proved useful for the detection of pheochromocytoma, neuroblastoma, and other neoplasms of neural crest origin. The authors present a case of a patient who was initially diagnosed as having follicular carcinoma of the thyroid in which I-131 MIBG played a key role in leading to the diagnosis of medullary carcinoma of the thyroid. Local and distant metastases were detected using I-131 MIBG imaging. Uptake of I-131 MIBG by medullary carcinoma of the thyroid has both diagnostic and therapeutic implications.

3-Iodobenzylguanidine↗
PubMed1980

Studies on osteoporosis III. Effect of estrogens and fluoride.

Total skeletal calcium levels were determined in female mice with the aid of whole body neutron activation analysis. Three months treatment with heparin produced significant osteoporosis in C3-H/St(Ha) mice but not in C57/BL6 (J) mice. Treatment with a conjugated natural estrogen preparation (Premarin) prevented heparin accelerated osteoporosis, but high level fluoride in the drinking water had no preventive effect. In some experiments there was a suggestion of a deleterious effect of fluoride.

Animals↗
PubMed1980

Studies on osteoporosis IV. Effect of benzo[b]thiophene-2- and dibenzothiophene-4-carboxylic acid on heparin accelerated osteoporosis.

Total skeletal calcium was determined in female mice with the aid of whole body neutron activation analysis. Three months treatment with heaprin produced significant osteoporosis in C3-H/St(Ha) mice but not in C57/BL6(J) mice. This was more pronounced in the younger (5-8 months) than in the older (15-18 months) animals. Two 2-thiophene carboxylic acid derivatives showed significant osteoporosis preventive activity.

Animals↗
PubMed1979

Studies on osteoporosis. II. Effect of estrogens and fluoride on experimental osteoporosis. A preliminary report.

Total skeletal calcium level was determined in female mice with the aid of whole body neutron activation analysis. Three months treatment with heparin produced significant osteoporosis in C3H/St(Ha) mice of 3--5 months of age. Treatment with a conjugated natural estrogen preparation (Premarin) prevented this phenomenon but high level fluoride in the drinking water failed to show preventive activity.

Animals↗
PubMed1978

Studies on osteoporosis I. Experimental models. Effect of age, sex, genetic background, diet, steroid and heparin treatment on calcium metabolism of mice.

C3H/St(Ha) and C57Bl/6(J) mice of both sexes and various ages were exposed to whole body neutron irradiation. The 49Ca generated (half life 8.8 minutes) was immediately determined in a whole body counter. Total body calcium content was calculated. It was assumed that 99% of this represented skeletal calcium. In females, significant decrease in calcium content occurred after 23 months of age. In C3H/St(Ha) mice, low calcium diet, heparin (500 i.u./Kg. b.i.d.) and prednisolone (50 mg/Kg) treatment accelerated calcium loss and produced significant decrease in 3 months. C57Bl/6(J) mice were less susceptible to the latter drugs.

Aging↗
PubMedDate not supplied

Meeting the challenge of consultation and collaboration: developing interactive teams.

The roles of special educators as consultants and collaborators have long been established and supported. The rationale for these roles is also well documented. Many models--consultative, collaborative, and teaming--have been suggested in the literature; sometimes, these models exhibit similar goals, competencies, and processes. Because of intensified pressures to collaborate, successful implementation of collaborative and team efforts requires that special educators expand their roles as interactive professionals. The purpose of this article is to define and describe the consultation, collaboration, and teaming models that have been implemented, discuss their strengths and limitations, delineate how these models contribute to interactive teaming, outline key features of the interactive team, and provide some guiding principles for successful implementation.

Cooperative Behavior↗