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Biomedical subjects

M Turner

Publications and source records attributed to M Turner.

At least 145 records · Page 8Linked to original sources
PubMed1997

Theatre usage for emergency surgery--use or abuse?

A prospective study was performed to characterise the activity in the designated Emergency Operating Theatre of a fourteen hundred bed teaching hospital. The main conclusion was that a large group of non-emergency but non-elective patients undergo surgery in this facility. The study has shown that in this hospital, despite apparently adequate emergency facilities including a separate orthopaedic trauma theatre, additional theatre time equivalent to six designated theatre sessions would be required to optimise the management of these patients who are often elderly and require major surgery.

Adolescent↗
PubMed1997

Multiple facial angiofibromas and collagenomas in patients with multiple endocrine neoplasia type 1.

OBJECTIVES: To evaluate patients with multiple endocrine neoplasia type 1 (MEN 1) for cutaneous manifestations. DESIGN: Survey during a 3-year period. SETTING: The National Institutes of Health, a tertiary referral research hospital in Bethesda Md. PATIENTS: A consecutive sample of 32 individuals with previously diagnosed MEN1 who were not preselected for the presence of skin lesions were examined for cutaneous abnormalities. None of the patients or family members were diagnosed as having tuberous sclerosis. INTERVENTIONS: Lesions were identified by clinical appearance, photographed, and confirmed histologically. MAIN OUTCOME MEASURE: To determine the frequency of skin lesions in patients with MEN1. RESULTS: Multiple facial angiofibromas were observed in 28 (88%) of the patients with MEN1, with 16 patients (50%) having 5 or more. Angiofibromas were clinically and histologically identical to those in individuals with tuberous sclerosis. Collagenomas were observed in 23 patients (72%). Also observed were cafe au lait macules in 12 patients (38%), lipomas in 11 patients (34%), confetti-like hypopigmented macules in 2 patients (6%), and multiple gingival papules in 2 patients (6%). CONCLUSIONS: Multiple angiofibromas, collagenomas, lipomas, confetti-like hypopigmented macules and multiple gingival papules are cutaneous manifestations of MEN1 and should be looked for in both family members of patients with MEN1 and individuals with hyperparathyroidism of other MEN1-associated tumors. Multiple angiofibromas can no longer be considered pathognomonic for tuberous sclerosis. The observation of angiofibromas in individuals without tuberous sclerosis necessitates further biochemical testing for MEN1.

Adolescent↗
PubMed1996

Critical role for the tyrosine kinase Syk in signalling through the high affinity IgE receptor of mast cells.

Activation of the high affinity IgE receptor (Fc epsilon RI) of mast cells, a member of the antigen receptor family, leads to the release of allergic mediators, a critical event in the onset of immediate hypersensitivity. Stimulation of Fc epsilon RI results in the rapid association and activation of the Syk tyrosine kinase. Using Syk-deficient mast cells we show that they fail to degranulate, synthesize leukotrienes and secrete cytokines when stimulated through Fc epsilon RI, conclusively demonstrating an essential role for Syk in Fc epsilon RI signalling. Furthermore, our data strongly supports a model of Fc epsilon RI engagement leading to the sequential activation of the tyrosine kinases Lyn and then Syk. A similar mechanism is likely to apply to signal transduction through all members of the antigen receptor family.

Animals↗
PubMed1996

A scanning electron microscope investigation of the effects of pollutants on the hepatopancreatic ceca of Gammarus pulex (L.).

Scanning electron microscope studies were performed on the peripheral muscle network (myoepithelium) of the hepatopancreatic ceca of Gammarus pulex (L.) exposed to lindane, copper, or 3, 4-dichloroaniline (3,4-DCA) for a 24-hr period. The structural integrity of the myoepithelium of gammarids from control and test treatments was assessed using semiquantitative techniques. The lowest observed effect concentrations for structural changes were determined as 29.8 microg liter-1 lindane, 55 microg liter-1 copper, and 8.7 mg liter-1 3,4-DCA. The sensitivity of the bioassay and the significance of the morphological changes observed in the hepatopancreatic ceca of G. pulex are discussed.

Aniline Compounds↗
PubMed1996

The raccoon as an animal model for upper limb neural prosthetics.

The raccoon was evaluated as an animal model for upper limb neural prosthetics. This animal was selected primarily because the functional use of its forelimb mimics in many ways the usage in humans and because of its optimal size and commercial availability. Eight cadaver and fresh specimen forearms were dissected. Important characteristics of the raccoon forearm were: 1) large muscles in the volar forearm, 2) large digits in the paw that appear more similar to humans than to other species such as cat or dog, 3) persistence of two median nerve cords into the forearm, 4) no separation of individual tendons of flexor digitorum superficialis and flexor digitorum profundus in the carpal tunnel, 5) a small thumb digit with little function and 6) a primary origin of flexor policis longus on the proximal ulna with a secondary origin on the radius. Four animals were anesthetized and responses of the forearm and paw to stimulation of the volar forearm muscles with percutaneous electrodes were evaluated. A pair of stimulating electrodes was placed in each of four muscles or muscle groups. Recording electrodes were placed in two muscles which showed the greatest separation of muscle movements to stimulation. Stimulation currents just above threshold produced discrete motion as well as recordable EMG M-waves. Incremental increases in stimulation current produced an increase in M-wave amplitude up to a maximal stimulating current. Torque recordings for pronation, wrist flexion and finger flexion showed graded and selective responses. These results including anatomical descriptions indicate both the limitations of this animal model and its potential use in the development of upper limb neural prosthetics. We conclude that the raccoon model may be superior to other nonprimate animal models such as the cat because of its extensive forearm and paw movements.

Animals↗
PubMed1995

Perinatal lethality and blocked B-cell development in mice lacking the tyrosine kinase Syk.

The tyrosine kinase Syk (relative molecular mass 72,000), which is widely expressed in haematopoietic cells, becomes associated with and activated by engagement of the B-cell antigen receptor. Furthermore, it has been implicated in signalling through the receptors for interleukin-2 (IL-2), granulocyte colony-stimulating factor (G-CSF) and Fc, the T cell receptor, as well as through receptors for several platelet agonists. A homologous kinase, ZAP-70, is crucial in signalling through the T-cell receptor and in T-cell development. Using homologous recombination in embryonic stem cells, we created mice null for the syk gene which showed petechiae in utero and died shortly after birth. Irradiated mice reconstituted with Syk-deficient fetal liver showed a block in B-cell development at the pro-B to pre-B cell transition, consistent with a key role for Syk in pre-B-cell receptor signalling. Despite the production of small numbers of immature B cells, Syk-deficient radiation chimaeras failed to accumulate mature B cells, indicating a possible role for this protein in the production or maintenance of mature B cells. In addition, whereas the development of alpha beta T cells proceeded normally, Syk-deficient mice showed impaired development of thymocytes using the V gamma 3 variable region gene (V gamma 3+ thymocytes). Finally, we show that Syk is not required for signalling through the IL-2 and G-CSF receptors.

Amino Acid Sequence↗
PubMed1995

Defective antigen receptor-mediated proliferation of B and T cells in the absence of Vav.

Crosslinking of B- or T-cell antigen receptors results in the rapid tyrosine phosphorylation of a number of proteins, including Vav, a protein expressed in cells of the haematopoietic system. Vav contains an array of structural motifs that include Src-homology domains SH2/SH3 and regions of homology to the guanine-nucleotide-exchange protein Dbl, pleckstrin and protein kinase C (refs 5-9). Using the RAG-complementation approach, we have analysed in vivo differentiation and in vitro responses of B- and T-lineage cells generated by injection of embryonic stem cells homozygous for a null mutation in the vav gene into blastocysts of RAG-1- or RAG-2-deficient mice. Here we report that antigen receptor-mediated proliferative responses of B and T cells in vitro are severely reduced in the absence of Vav. We also suggest a direct link between the low proliferative response of Vav-deficient B and T cells and the reduced number of these cells in peripheral lymphoid organs of chimaeric mice.

Animals↗
PubMed1995

Sympathetic nervous system influences salt appetite in four strains of rats.

Sodium appetite and preference were examined in four rat strains using a social stressor and drugs to block sympathetic nervous system (SNS) activity. We have studied these strains for over 14 yr in our laboratory and the SHR strain has increased blood pressure and increased sympathetic nerve activity. The F1 crosses produce male offspring with the Y chromosome from a hypertensive or normotensive father, to examine its influence on sodium appetite. The pharmacological manipulation produces blockage of the SNS which may be partially responsible for stress induced sodium appetite. The objectives were to determine: (i) if the SNS was necessary for stress induced increased salt appetite; and (ii) if the Y chromosome from a hypertensive father increased salt intake or preference. Four strains (n = 6-8/group) of male rats were studied from 3-6 mo of age: normotensive Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHR) and hybrid crosses between a WKY mother and SHR father (WS) and the reciprocal cross (SW). Each group consumed Purina rat chow (0.3% Na) and was given a four-bottle choice of salt water ad lib (0.0%, 0.5%, 1.0%, and 1.5% NaCl). Social stress produced by intruder males significantly increased salt intake in all groups. SHR had higher salt intake than WKY both before and after exposure to intruder stress. In general, the SHR group preferred twice the concentration of saline (1.0%) as did the WKY (0.5%). Clonidine and reserpine both reduce SNS activity and consequently reduced salt intake after stress, from 20-44% depending on the genetic background of the rat strain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Satisfaction and continuity of care: staff views of care in a midwife-managed delivery unit.

OBJECTIVE: to examine whether there are differences in the midwife's role in, and satisfaction with, intrapartum care and delivery of women at low obstetric risk in a midwife-managed delivery unit compared to a consultant-led labour ward. DESIGN: a pragmatic randomised controlled trial. Subjects were randomised in a 2:1 ratio between the midwives' unit and the labour ward. SETTING: Aberdeen Maternity Hospital, Grampian, UK. SUBJECTS: midwives within the delivery suite who cared for the 2844 women at low obstetric risk receiving care in a pragmatic randomised controlled trial of the two delivery areas. PRIMARY OUTCOME MEASURES: continuity of carer and midwife satisfaction. FINDINGS: midwives looking after women in the midwives' unit group were significantly more likely to be of a higher grade, more qualified and have a longer length of experience than those in the labour ward group. There was greater continuity of carer both during labour and after delivery in the midwives' unit group. Despite a small but statistically significant difference in overall satisfaction between the groups, area of 'booking' or area of delivery were not important in predicting midwife satisfaction. Autonomy and continuity of carer were the best predictors of midwife satisfaction. CONCLUSIONS: midwife-managed intrapartum care increases continuity of carer and, therefore, midwife satisfaction. Extending this outside the delivery suite requires a system of care that is acceptable to midwives as well as women. Such systems will depend to a large extent on geography, consumer demand and availability of resources. However, midwife satisfaction should also be considered. In order to do this further research is required to fully evaluate the effect these systems have on the midwives working in them.

Attitude of Health Personnel↗
PubMed1995

DNA quantification is technically feasible and of value in cervical smear samples: possible applications for determination of progression in low grade dyskaryosis.

This study evaluates the feasibility of DNA analysis of cervical intraepithelial neoplasia III (CIN III) lesions on cervical smear and formalin-fixed paraffin-embedded tissue (FFPET) blocks with a view to extending this type of analysis to milder grades of dyskaryosis. DNA ploidy was determined by image analysis using a CAS 200 Image Analyser. Seventeen patients with a diagnosis of CIN III were studied. Results show that all smear and tissue samples were non-diploid with nine aneuploid and eight tetraploid lesions. In 6/7 patients whose smears and corresponding biopsies were examined there was complete agreement as to the DNA profile. We conclude that DNA quantification is technically feasible in archival, routinely prepared cervical smears. This technique should now be applied to CINI and CINII cervical smears to determine if it is of value in identifying those lesions that will progress to CIN III. This study is particularly timely with the possibility in the near future of estimation of ploidy by image analysis using instruments such as the Highly Optimized Microscope Environment (HOME) system.

Aneuploidy↗