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Biomedical subjects

Sam Martin

Publications and source records attributed to Sam Martin.

7 recordsLinked to original sources
PubMed2006

Recording strategies and selection potential of feed intake measured using the X-ray method in rainbow trout.

This study examines the way long-term feed intake should be recorded accurately for selective breeding purposes, and estimates selection potential in feed intake using the X-ray method to record individual daily feed intake in rainbow trout (Oncorhynchus mykiss). The analysis showed that the point estimates of daily feed intake displayed low repeatabilities (r = 0.09-0.32). This indicates that a minimum of three repeated records were needed to accurately record average feed intake at a fixed age. To effectively breed for feed intake over the whole growing period, it is necessary to determine average feed intake at different ages, since there were only moderate phenotypic and genetic correlations between average daily feed intake recorded at 140 g, 750 g and 2000 g wet mass. Heritability for average daily feed intake was low (average h(2) = 0.10), indicating that modest genetic changes can be obtained in response to selection. It was concluded that selection to genetically change long-term feed intake can be successful, yet repeated observations at several life stages are needed to ensure the accuracy of feed intake estimates and the efficiency of selection.

Animal Feed↗
PubMed2006

A novel activating mutation in the RET tyrosine kinase domain mediates neoplastic transformation.

We report the finding of a novel missense mutation at codon 833 in the tyrosine kinase of the RET proto-oncogene in a patient with a carcinoma of the thyroid. In vitro experiments demonstrate that the R833C mutation induces transformed foci only when present in the long 3' splice isoform and, in keeping with a model in which the receptor has to dimerize to be completely activated, glial cell line-derived neurotrophic factor stimulation leads the RET(R833C) receptor to a higher level of activation. Tyrosine kinase assays show that the RET(R833C) long isoform has weak intrinsic kinase activity and phosphorylation of an exogenous substrate is not elevated even in the presence of glial cell line-derived neurotrophic factor. Furthermore, the R833C mutation is capable of sustaining the transformed phenotype in vivo but does not confer upon the transformed cells the ability to degrade the basement membrane in a manner analogous to metastasis. Our functional characterization of the R833C substitution suggests that, like the V804M and S891A mutations, this tyrosine kinase mutation confers a weak activating potential upon RET. This is the first report demonstrating that the introduction of an intracellular cysteine can activate RET. However, this does not occur via dimerization in a manner analogous to the extracellular cysteine mutants.

Animals↗
PubMed2006

Perioperative care of the child with arthrogryposis.

BACKGROUND: Arthrogryposis multiplex congenita (AMC) is a congenital symptom complex characterized by multiple joint contractures. AMC results from fetal akinesia due to extrinsic factors (oligohydramnios) or primary neurogenic or myopathic conditions of the fetus. METHODS: We retrospectively reviewed our perioperative experience in 12 patients with AMC. RESULTS: Intraoperative issues noted in our patients included difficulties with peripheral IV placement (n = 3), difficult tracheal intubation (n = 4), and intraoperative hyperthermia (n = 4). Difficulties with peripheral IV placement were more common in younger patients (2.3 +/- 0.6 vs 9.2 +/- 3.5 years). Although easy bag-valve-mask ventilation was present in all 12 patients, difficulty with tracheal intubation was noted in four patients. In these four patients, the airway was secured using an LMA (n = 3) or a facemask (n = 1). The patients in whom difficulties with tracheal intubation were encountered were older than patients in whom no difficulties were noted (11.0 +/- 2.9 vs 5.8 +/- 3.9 years). Four patients developed intraoperative temperatures > or =37 degrees C; however, there was no evidence of hypercarbia or tachycardia suggestive of malignant hyperthermia. Postoperative issues included stridor (n = 2) and postoperative atelectasis (n = 3). CONCLUSIONS: The perioperative care of patients with AMC should consider not only the physical manifestations of the disease process, but also the implications of the underlying neuromuscular disease. The most common perioperative issues included difficulties with airway management, problematic intravenous access, and intraoperative hyperthermia.

Adolescent↗
PubMed2005

Polymorphisms in the initiators of RET (rearranged during transfection) signaling pathway and susceptibility to sporadic medullary thyroid carcinoma.

CONTEXT: Medullary thyroid carcinoma (MTC) is a characteristic tumor occurring in individuals with multiple endocrine neoplasia type 2 who carry germ-line mutations in RET (rearranged during transfection). However, most MTC occur in individuals without a family history. OBJECTIVES: The objective of this study was to explore the possibility that susceptibility in these cases results from low penetrance alleles of RET, its coreceptors, and ligands. DESIGN: We carried out an association study in 135 sporadic MTC (sMTC) patients and 533 controls from the United Kingdom population. RESULTS AND CONCLUSIONS: We analyzed 33 polymorphisms in all nine genes involved in the glial cell line-derived neurotropic factor receptor-alpha (GFRalpha)-RET complex. This is the first association study in which all genes involved in this complex have been investigated for susceptibility to sMTC. We did not find any association between single nucleotide polymorphisms in the exonic regions of the GFRalpha2, GFRalpha3, GFRalpha4, glial cell line-derived neurotropic factor, neurturin, or persephin genes and risk of developing sMTC. We found a strong association between the disease and specific haplotypes of RET. We not only confirmed the previously described association with G691S and S904S (for heterozygotes: odds ratio, 1.85; range, 1.22-2.82; P = 0.004), but we found a novel protective effect associated with a specific haplotype (odds ratio, 0.39; range, 0.21-0.72; P = 0.005) revealing the existence of different genetic variants in the RET oncogene that either increase or decrease risk of sMTC.

Adolescent↗
PubMed2003

Impact of a Graduate Entry Programme on a medical school library service.

The aim of this study was to compare the use of library facilities by first year undergraduate medical students and Graduate Entry Programme students (GEP). More specifically it tried to determine which library services (if any) were more frequently used by GEP so that this could be taken into account in future Information Services planning. A questionnaire on the use of Library and Information Services was posted to all first year GEP students and undergraduates on the 5-year course. In addition, user statistics of library entry and borrowing were collated from gate readings and the library Unicorn management system. Overall, GEP students were found to make a greater daily/weekly use of library facilities than undergraduates on the 5-year course. The facilities most used by both sets of students were essential texts, e-mail, PCs and study facilities. Computer Aided Learning packages, journals and video facilities were least used. However, on a daily/weekly basis GEP students made 74% more use of journals (P < 0.01), 59% more use of e-journals (P < 0.05), 36% more use photocopiers (P < 0.05), 42% more use of printers (P < 0.05), 56% more use of the library catalogue (P < 0.05) and 50% more use of databases (P < 0.05). This difference in use should be taken into account by LIS providers as there is expected to be an increase in fast-track graduate courses offered by medical schools throughout the UK.

Curriculum↗
PubMed1999

Functional features of the bovine enterovirus 5'-non-translated region.

The bovine enterovirus (BEV) serotypes exhibit unique features of the non-translated regions (NTRs) which separate them from the other enteroviruses. Their most remarkable property is an additional genome region of 110 nt located between the 5'-cloverleaf and the internal ribosome entry site (IRES). This genome region has the potential to form an additional cloverleaf structure (domain I*) separated from the 5'-cloverleaf (domain I) by a small stem-loop (domain I**). Other characteristics involve the putative IRES domains III and VI. In order to investigate the features of the 5'-NTR, several full-length coxsackievirus B3 (CVB3) cDNA plasmids with hybrid 5'-NTRs were engineered. After exchange of the CVB3 cloverleaf with the BEV1 genome region representing both cloverleafs, a viable virus chimera was generated. Deletion of domain I** within the exchanged region also yielded viable virus albeit with reduced growth capacity. Deletion of sequences encoding either the first or the second BEV cloverleaf resulted in non-infectious constructs. Hybrid plasmids with exchanges of the IRES-encoding sequence or the complete 5'-NTR were non-infectious. Transfection experiments with SP6 transcripts containing 5'-NTRs fused to the luciferase message indicated that IRES-driven translation is enhanced by the presence of the CVB3 cloverleaf and both BEV1 cloverleaf structures, respectively. Deletion of either the first or the second BEV cloverleaf domain reduced but did not abolish enhanced luciferase expression. These results suggest that the substitution of two putative BEV cloverleaf structures for the putative coxsackieviral cloverleaf yields viable virus, while BEV sequences encoding the IRES fail to functionally replace CVB3 IRES-encoding sequences.

5' Untranslated Regions↗