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Biomedical subjects

F W Smith

Publications and source records attributed to F W Smith.

At least 19 recordsLinked to original sources
PubMed2006

A complex fracture of the talus following a rugby union line-out.

Fractures of the talus are frequently difficult to treat. The vulnerable blood supply and abundant articular surfaces may lead to long-term problems with avascular necrosis and osteoarthritis. A case of a complex injury to the talus occurring in a rugby union player during a line-out is presented. The laws relating to line-out play disallow "lifting" and "levering" in the line out, but in reality allow "supporting" of the jumper on his shorts, once he has jumped. A further law insists on "lowering" of the supported jumper to the ground as soon as the ball has been won. This unusual injury to the talus clearly demonstrates the potential dangers of the line-out and the necessity that the laws of the game must be strictly adhered to, in order to ensure the safety of the line-out jumper.

Adult↗
PubMed2004

Characterization of promoter expression patterns derived from the Pht1 phosphate transporter genes of barley (Hordeum vulgare L.).

By comparison with dicot plant species, relatively little work has been reported on the phosphate transporter (Pht1) gene family from monocot species. Initial studies have shown that barley contains at least eight homologous genes. The promoters of six of these genes were analysed for the presence of regulatory elements potentially associated with expression specificity. In particular, the P1BS-like elements (implicated in phosphorus-regulated expression of genes in plants) was identified in all HvPht1 promoters examined. For two members of the family (HvPht1;1 and HvPht1;2), promoter fusions to beta-glucuronidase and green fluorescent protein reporter genes were constructed, transformed into rice, and the expression profiles observed. The inclusion of an intron derived from Adh1 enhanced gene expression approximately 20-fold, but did not appear to affect the specificity of expression. The HvPht1;1 and HvPht1;2 promoters showed minor differences in expression patterns but, in general, expression was observed at high levels in trichoblast cells (root hairs) and stele of the nodal root, throughout secondary roots, and at a relatively low level in leaf tissues. Under phosphorus deficiency, expression was induced by up to 5-fold. These observations are consistent with a primary role for the encoded genes in the uptake of phosphate by root hairs from soil solution and further current understanding of the mechanisms involved. The promoters also have application for providing a new resource for cereal transformation, ideally suited for driving the expression of foreign genes associated with nutrient uptake.

Base Sequence↗
PubMed2004

Subjective functional assessments and the return to competitive sport after anterior cruciate ligament reconstruction.

OBJECTIVES: To examine (a) return to competitive sport within 12 months of anterior cruciate ligament (ACL) reconstruction, (b) maintenance of competitive participation at follow up, and (c) the relation of the level of sports activity and competitive participation at follow up to subjective functional assessments. Also to address the incidence of continued competitive participation despite notable functional problems with the operated knee at 12 months and follow up. METHODS: All patients were competitive athletes before injury and had undergone ACL reconstruction by the transtibial endoscopic technique with either a bone-patellar tendon-bone or a multiple looped hamstring autograft. Evaluation was carried out a mean of 43 months (range 24-73) after surgery by a postal questionnaire in which the Cincinnati sports activity scale (CSAS) and Cincinnati sports function scales were presented in conjunction with closed questions on change in competitive level and the presence of complaints. RESULTS: Of 109 selected patients, 77 (71%) responded. At follow up, 62 of 77 patients (81%) reported that they had returned to competition within 12 months of surgery. Within the same time frame, 55 of the above 62 patients (89%) also claimed to have returned to the level at which they were competing before injury (or higher). At follow up, 30 of the above 55 patients (54%) reported to still be competing at this high level. Twelve of the above 55 patients (22%) also admitted to major problems with the operated knee at that time. The overall incidence of patients competing despite major functional impairment in the operated knee was 13 of 62 (21%) at 12 months and six of 47 (13%) at follow up. Thirty eight patients (49%) were active in sport at least four times a week at follow up (CSAS level 1), and, using Spearman's rank correlation between CSAS scores and total sports function scores, r was calculated to be 0.44. Competitive and male patients had higher total sports function scores at follow up than non-competitive (p = 0.005) and female (p = 0.02) patients respectively. CONCLUSIONS: The reported return to competition at the previous level, both within 12 months and at follow up, was high but as expected considering the standard of treatment, patient selection, and study exclusion criteria. Patients with few functional complaints maintained a high level of sporting activity, even after discontinuing competitive participation.

Anterior Cruciate Ligament↗
PubMed2003

Axial compression generated by cortical and cancellous lag screws in the equine distal phalanx.

Lag screw fixation using single 4.5 mm cortical bone screws is a recommended technique for repair of mid-sagittal plane fractures of the distal phalanx in adult horses. However, implant infection and technical difficulties in obtaining adequate interfragmentary compression have made this surgical procedure somewhat controversial. We hypothesized that use of larger diameter screws would result in increased axial compression and improved stability of this fracture. Paired distal phalanges from the forelimbs of 10 adult horses were collected at necropsy and divided in half in the midsagittal plane. Using a randomized block study design, four types of bone screws (4.5 mm cortical, 5.5 mm cortical, 6.5 mm cancellous pre-tapped, and 6.5 mm cancellous non-tapped) were inserted to a depth of 15 mm. During screw insertion, the axial force generated under the screw head was measured with a load washer containing a piezoelectric force transducer, while torque of insertion was recorded with a torsional testing machine. The 6.5mm screw inserted after pre-tapping generated significantly greater axial force (2781 N) than the 4.5 mm (1522 N), 5.5 mm (2073 N) or 6.5 mm non-tapped (2295 N) screws. The relationship between maximal applied torque and axial force generated was linear for each screw type. Each unit of torque applied during insertion of cortical screws resulted in a greater increase in axial compression, as compared to cancellous screws. These data suggest that use of larger diameter screws would result in improved interfragmentary compression of distal phalangeal fractures.

Animals↗
PubMed2002

Measurement of the bony anatomy of the humerus using magnetic resonance imaging.

This study was undertaken during the development of a new humeral intramedullary nail. To determine the overall size of the nail it was necessary to have the dimensions of the humerus and intramedullary canal. The dimensions of the bony anatomy of the humerus were obtained using an open magnetic resonance imager. The right arm of 20 volunteers was scanned and the length and the dimensions of both the intramedullary canal and the cortical bone were measured. The diameter of the canal was found to be 12.1+/-2.6 mm (mean +/- standard deviation) with the middle 50 per cent of measurements between 10 and 14 mm. The overall diameter of the bone was 19.3+/-2.3 mm, with the middle 50 per cent of measurements between 18 and 21 mm. This study has shown that magnetic resonance imaging (MRI) is an effective method of collecting dimensional data from any part of the skeleton for the development of medical devices.

Adult↗
PubMed2001

Magnetic resonance imaging assessment of a sinus lift operation using reoxidised cellulose (Surgicel) as graft material.

Various materials have been used for bone grafts in the sinus lift operation, to increase the vertical bone height in the maxilla before the placement of dental implants in the atrophic maxilla. In this case history, Surgicel (oxidised regenerated cellulose) was used as a graft material for one patient, allowing successful delayed implant placement within new and existing bone. The sinus region was examined three months after grafting with Surgicel using magnetic resonance imaging (MRI). The MR images showed that material of similar MR signal to bone had formed within the graft. MRI allowed us to gain tomographic information of the region without exposure of the patient to ionising radiation. The formation of bone within the Surgicel matrix was confirmed at implant placement. This poses interesting questions as to the physiology of bone formation within non-particulate graft material, warranting further investigation.

Alveolar Ridge Augmentation↗
PubMed2001

Magnetic resonance imaging of the human cervix: a study of the effects of prostaglandins in the first trimester.

BACKGROUND: To establish that magnetic resonance imaging (MRI) can provide an objective measurement of the biophysical state of the cervix and to measure the response of the cervix to prostaglandins in the first trimester of pregnancy. METHODS: A comparative study, with each patient serving as her own control, was carried out on 10 primigravid women with 49--84 days amenorrhoea undergoing surgical termination of pregnancy. Each woman had two MRI scans of the uterus and cervix. The first scan was performed prior to administration of prostaglandins and the second scan 2.5--3 h following an 800 microg dose of misoprostol given vaginally. Cervical change was assessed by measurement of cervical length, transverse diameter of the cervix, diameter of the internal os and cervical stromal signal intensity. RESULTS: A significant difference in cervical length (P = 0.012), transverse diameter (P = 0.001) and diameter of the internal os (P = 0.008) was detected following the administration of misoprostol. In five women a significant change in one or both components of the cervical stromal signal was detectable and in five women no change could be demonstrated. CONCLUSION: MRI is capable of detecting changes in the physical parameters of the cervix following administration of prostaglandin. However, the changes detected in the stromal signal intensity are less consistent. The potential of MRI as a clinical tool to monitor cervical changes in a variety of clinical situations warrants further investigation.

Abortion, Induced↗
PubMed2001

Diagnosis of lumbosacral nerve root anomalies by magnetic resonance imaging.

This study evaluates the use of magnetic resonance imaging (MRI) in the diagnosis of lumbosacral nerve root anomalies. Prevalence of anomalous nerve roots has been based on anatomic dissection or preoperative neuroradiologic investigations. Three hundred seventy-six patients with low back pain and/or radicular pain who underwent MRI of the lumbar spine were reviewed. Sixty-five cases of nerve root anomalies were found (an incidence of 17.3%) of which 1 case of cranial origin, 5 cases of caudal origin, 2 cases of conjoined nerve root, and 57 cases of furcal nerve roots (15.1%) were identified. Furcal nerve roots were most commonly found at L3 and L4 levels and were classified, according to their division, into intra-and extraforaminal. MRI provided accurate information on lumbosacral nerve root anomalies.

Humans↗
PubMed2000

Molecular mechanisms of phosphate and sulphate transport in plants.

The application of molecular techniques in recent years has advanced our understanding of phosphate and sulphate transport processes in plants. Genes encoding phosphate and sulphate transporters have been isolated from a number of plant species. The transporters encoded by these genes are related to the major facilitator superfamily of proteins. They are predicted to contain 12 membrane-spanning domains and function as H(+)/H(2)PO(-4) or H(+)/SO(2/-4) cotransporters. Both high-affinity and low-affinity types have been identified. Most research has concentrated on genes that encode transporters expressed in roots. The expression of many of these genes is transcriptionally regulated by signals that respond to the nutrient status of the plant. Nutrient demand and the availability of precursors needed in the assimilatory pathways also regulate transcription of some of these genes. Information on the cell types in which phosphate and sulphate transporters are expressed is becoming available. These data, together with functional characterisation of the transporters, are enabling the roles of various transporters in the overall phosphate and sulphate nutrition of plants to be defined.

Biological Transport↗
PubMed2000

The roles of three functional sulphate transporters involved in uptake and translocation of sulphate in Arabidopsis thaliana.

To investigate the uptake and long-distance translocation of sulphate in plants, we have characterized three cell-type-specific sulphate transporters, Sultr1;1, Sultr2;1 and Sultr2;2 in Arabidopsis thaliana. Heterologous expression in the yeast sulphate transporter mutant indicated that Sultr1;1 encodes a high-affinity sulphate transporter (Km for sulphate 3.6 +/- 0.6 microM), whereas Sultr2;1 and Sultr2;2 encode low-affinity sulphate transporters (Km for sulphate 0.41 +/- 0.07 mM and >/= 1.2 mM, respectively). In Arabidopsis plants expressing the fusion gene construct of the Sultr1;1 promoter and green fluorescent protein (GFP), GFP was localized in the lateral root cap, root hairs, epidermis and cortex of roots. beta-glucuronidase (GUS) expressed with the Sultr2;1 promoter was specifically accumulated in the xylem parenchyma cells of roots and leaves, and in the root pericycles and leaf phloem. Expression of the Sultr2;2 promoter-GFP fusion gene showed specific localization of GFP in the root phloem and leaf vascular bundle sheath cells. Plants continuously grown with low sulphate concentrations accumulated high levels of Sultr1;1 and Sultr2;1 mRNA in roots and Sultr2;2 mRNA in leaves. The abundance of Sultr1;1 and Sultr2;1 mRNA was increased remarkably in roots by short-term stress caused by withdrawal of sulphate. Addition of selenate in the sulphate-sufficient medium increased the sulphate uptake capacity, tissue sulphate content and the abundance of Sultr1;1 and Sultr2;1 mRNA in roots. Concomitant decrease of the tissue thiol content after selenate treatment was consistent with the suggested role of glutathione (GSH) as a repressive effector for the expression of sulphate transporter genes.

Arabidopsis↗
PubMed2000

Correlation between the MRI changes in the lumbar multifidus muscles and leg pain.

AIM: In the assessment of the lumbar spine by magnetic resonance imaging (MRI), changes in the paraspinal muscles are frequently overlooked. In this study, our objective was to investigate the relationships between lumbar multifidus (MF) muscle atrophy and low back pain (LBP), leg pain and intevertebral disc degeneration. METHODS: A retrospective study of 78 patients (aged 17-72) with LBP presenting with back pain with or without associated leg pain was undertaken. Their MR images were visually analysed for signs of lumbar MF muscle atrophy, disc degeneration and nerve root compression. The clinical history in each case was obtained from their case notes and pain drawing charts. RESULTS: MF muscle atrophy was present in 80% of the patients with LBP. The correlation between MF muscle atrophy and leg pain was found to be significant (P < 0.01). However, the relationships between muscle atrophy and radiculopathy symptoms, nerve root compression, herniated nucleus pulposus and number of degenerated discs were statistically not significant. CONCLUSION: Examination of the paraspinal muscles looking for atrophy of MF muscle should be considered when assessing MR images of lumbar spine. This may explain the referred leg pain in the absence of other MR abnormalities.

Adolescent↗
PubMed2000

Inflammatory abdominal aortic aneurysms: diagnosis with gadolinium enhanced T1-weighted imaging.

AIM: Inflammatory abdominal aortic aneurysms (IAAA) are a variant of abdominal aortic aneurysms, which are associated with an increased morbidity. The diagnosis of IAAA has traditionally been established with a combination of clinical and laboratory findings together with contrast enhanced CT. There is a high incidence of renal impairment in this group, and therefore contrast enhanced CT may be harmful. PATIENTS AND METHODS: Five patients with IAAA underwent T1-weighted spin echo and gradient echo gadolinium enhanced abdominal MRI. A total of eight examinations were performed, including three patients who underwent repeat MRI following steroid therapy. RESULTS: The inflammatory cuff was clearly identified following gadolinium administration in all eight examinations. The cuff enhanced homogeneously in all patients with no alteration in appearance following steroid therapy. The intravenous administration of gadolinium DTPA enabled clearer definition of locally involved structures. CONCLUSION: Gadolinium enhanced MRI readily demonstrates features of IAAA. In view of potential renal impairment in this patient group, we recommend this technique in preference to contrast enhanced CT in the initial investigation of inflammatory abdominal aortic aneurysms.

Aged↗
PubMed2000

Zinc deficiency up-regulates expression of high-affinity phosphate transporter genes in both phosphate-sufficient and -deficient barley roots.

Phosphate (P) is taken up by plants through high-affinity P transporter proteins embedded in the plasma membrane of certain cell types in plant roots. Expression of the genes that encode these transporters responds to the P status of the plants, and their transcription is normally tightly controlled. However, this tight control of P uptake is lost under Zn deficiency, leading to very high accumulation of P in plants. We examined the effect of plant Zn status on the expression of the genes encoding the HVPT1 and HVPT2 high-affinity P transporters in barley (Hordeum vulgare L. cv Weeah) roots. The results show that the expression of these genes is intimately linked to the Zn status of the plants. Zn deficiency induced the expression of genes encoding these P transporters in plants grown in either P-sufficient or -deficient conditions. Moreover, the role of Zn in the regulation of these genes is specific in that it cannot be replaced by manganese (a divalent cation similar to Zn). It appears that Zn plays a specific role in the signal transduction pathway responsible for the regulation of genes encoding high-affinity P transporters in plant roots. The significance of Zn involvement in the regulation of genes involved in P uptake is discussed.

Carrier Proteins↗
PubMed1999

The effect of sodium, potassium and ammonium ions on the conformation of the dimeric quadruplex formed by the Oxytricha nova telomere repeat oligonucleotide d(G(4)T(4)G(4)).

The DNA sequence d(G(4)T(4)G(4)) [Oxy-1.5] consists of 1.5 units of the repeat in telomeres of Oxytricha nova and has been shown by NMR and X-ray crystallographic analysis to form a dimeric quadruplex structure with four guanine-quartets. However, the structure reported in the X-ray study has a fundamentally different conformation and folding topology compared to the solution structure. In order to elucidate the possible role of different counterions in this discrepancy and to investigate the conformational effects and dynamics of ion binding to G-quadruplex DNA, we compare results from further experiments using a variety of counterions, namely K(+), Na(+)and NH(4)(+). A detailed structure determination of Oxy-1.5 in solution in the presence of K(+)shows the same folding topology as previously reported with the same molecule in the presence of Na(+). Both conformations are symmetric dimeric quadruplexes with T(4)loops which span the diagonal of the end quartets. The stack of quartets shows only small differences in the presence of K(+)versus Na(+)counterions, but the T(4)loops adopt notably distinguishable conformations. Dynamic NMR analysis of the spectra of Oxy-1.5 in mixed Na(+)/K(+)solution reveals that there are at least three K(+)binding sites. Additional experiments in the presence of NH(4)(+)reveal the same topology and loop conformation as in the K(+)form and allow the direct localization of three central ions in the stack of quartets and further show that there are no specific NH(4)(+)binding sites in the T(4)loop. The location of bound NH(4)(+)with respect to the expected coordination sites for Na(+)binding provides a rationale for the difference observed for the structure of the T(4)loop in the Na(+)form, with respect to that observed for the K(+)and NH(4)(+)forms.

Animals↗
PubMed1999

Measurement of abdominal fat by magnetic resonance imaging, dual-energy X-ray absorptiometry and anthropometry in non-obese men and women.

OBJECTIVE: To investigate whether the dual-energy X-ray absorptiometry (DEXA) was a better predictor of abdominal fat, measured by magnetic resonance imaging (MRI) at the level of L2-L3, than anthropometric measurements in non-obese men and non-obese women. DESIGN: Observational, cross sectional study. SUBJECTS: 34 healthy subjects (17 men and 17 women) aged 20-53 y with a body mass index (BMI) < 30 kg/m2. MEASUREMENTS: Fat distribution parameters including waist circumference and waist-to-hip ratio (WHR); intra abdominal fat (IAF) by MRI; and central abdominal fat (CAF) by DEXA. RESULTS: Measurement of IAF by MRI, was highly correlated to the CAF measured by DEXA. In men, both waist circumference and WHR had similar correlation to IAF as DEXA. In women, waist circumference was less well correlated with IAF than DEXA, and the WHR had a weaker non significant correlation with IAF. CONCLUSIONS: In non-obese men; DEXA, waist circumference and WHR can predict IAF equally well, while in non-obese women, DEXA is superior to waist circumference and much better than WHR.

Abdomen↗
PubMed1999

Assessment of the sinus lift operation by magnetic resonance imaging.

Sinus lift operations are done to increase bone thickness before placement of osseointegrated implants in areas of the maxilla where there is insufficient bone between the lower border of the maxillary sinus mucosa and the oral mucoperiosteum. Full sectional information should be available to the surgeon before the sinus lift operation so that the outcome can be predicted, and to allow for assessment of the volume of bone graft required. It is also useful to assess the success of the procedure before placement of the implant, and to choose the implant length and orientation required for maximum stability. We describe the use of a 0.2 tesla magnetic resonance imaging (MRI) scanner to image a patient before and after sinus lift. MRI gave full sectional information of the bone on both occasions without using ionizing radiation. The quality of the images was good, and should be considered as an alternative to the accepted gold standard of computed tomography (CT), which exposes the patient to a high dose of radiation.

Bone Transplantation↗
PubMed1998

Magnetic resonance imaging: a useful tool for evaluation of bone prior to implant surgery.

OBJECTIVE: To illustrate the potential for use of magnetic resonance imaging (MRI) to gain full sectional information before placement of osseo-integrated dental implants, with no patient exposure to ionising radiation. MATERIALS AND METHODS: Four typical cases are illustrated, the patients being imaged in a one tesla MRI scanner. The setting up of the sequences is explained, along with the use of an imaging/surgical template with gadolinium markers. RESULTS: MRI clearly shows full sectional detail of available bone for safe implant placement, and allows the delineation of cortical and cancellous bone to attain maximum implant length and stability. Vital structures and the floor of the maxillary sinus are clearly shown. CONCLUSIONS: MRI allows the surgeon to assess cases for suitability to place dental implants with confidence. The ability to scan directly at any desired plane, with no reformatting, and to relate this information to a surgical template gives predictable surgery. MRI is a sectional imaging modality giving information about the 3-dimensional relationship of the vital structures, without using ionising radiation. It therefore deserves consideration as an alternative to computed tomography. However, further work is indicated to investigate the relative technical merits of the two imaging modalities.

Adult↗