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Biomedical subjects

R L Guy

Publications and source records attributed to R L Guy.

At least 19 recordsLinked to original sources
PubMed2004

Embolisation of a post-traumatic superior gluteal artery aneurysm: case report.

Pseudoaneurysms of the superior gluteal artery are a rare complication of trauma. They can be diagnosed by Doppler ultrasound, computed tomography or magnetic resonance imaging. Angiography, however, is needed for definitive diagnosis. Transcatheter embolisation is now regarded as the treatment of choice. We present a case of superior gluteal artery pseudo-aneurysm following minor blunt trauma. The patient was successfully treated by transcatheter embolisation and aspiration.

Accidental Falls↗
PubMed2000

A fluorescence microscopy based genetic screen to identify mutants altered for interactions with host cells.

The study of microbial intracellular pathogenesis has benefited from the application of immunofluorescence microscopy to characterize interactions of the pathogen with host cells. Unfortunately, immunofluorescence microscopy is impractical for screening the large number of bacterial mutants necessary to represent the entire genome of the pathogen. Screening has been limited due to the lack of materials suitable for high-throughput processing (e.g. 96-well plates) that also possess the optical features needed for high resolution fluorescence microscopy. Recently marketed 96-well Special Optics (SO) plates provide both the 96-well template ideal for high-throughput analysis and optical features suitable for fluorescence microscopy. Until this work, mutants needed for the study of a fluorescence-based virulence phenotype could not be obtained by direct screening approaches. In this study, SO plates were used to examine 11520 individual Salmonella typhimurium MudJ mutants for the loss of the ability to disrupt host cell endocytic compartments. The direct application of the fluorescence phenotype for screening allowed us to obtain a set of mutants to characterize the formation of lysosomal membrane glycoprotein (lgp) containing tubules upon Salmonella infection of HeLa epithelial cells. This approach will facilitate the characterization of a wide range of microbial phenotypes detectable by fluorescence microscopy.

Antigens, CD↗
PubMed2000

Aggregation of host endosomes by Salmonella requires SPI2 translocation of SseFG and involves SpvR and the fms-aroE intragenic region.

Salmonella-induced aggregation of host endosomal compartments into tubules, termed lgp-tubules, requires sifA and ompR. Lgp-tubules result from Salmonella-directed alteration of the endocytic system and typify the unique intracellular locale where Salmonella replicate. A high-throughput method devised to screen 11 520 MudJ mutants for loss of lgp-tubule formation identified one auxotrophic and nine prototrophic mutants. Molecular characterization identified four new loci required to alter epithelial endocytic structure. Salmonella pathogenicity island 2 (SPI2) is the locus central to the phenotype. A subset of SPI2 effectors is essential: SpiC and SseFG are required, but not SseE. A subset of apparatus proteins is also implicated: SsaJ, L, M, V and P are required. SPI2 was implicated further, as SifA shows similarity with known SPI2 translocation targets, and OmpR regulates SPI2. Another locus lies within the smf-aroE intragenic region. Lgp-tubule formation also involves a locus on the virulence plasmid pSLT. The pSLT-encoded SpvR negatively regulates an unknown repressor of the phenotype located on pSLT. Finally, disruption of carB leads to multiple auxotrophy that prevents lgp-tubule formation. This study demonstrates that lgp-tubule formation is a virulence mechanism that underlies the selective disruption of host endocytic trafficking and is associated with the formation of a replication-permissive locale.

Amino Acid Sequence↗
PubMed1996

Primary breast cancer: mammographic changes after neoadjuvant chemotherapy, with pathologic correlation.

PURPOSE: To correlate changes depicted at mammography during neo-adjuvant chemotherapy for operable breast carcinoma with subsequent pathologic status. MATERIALS AND METHODS: Patients (n = 107) underwent mammography before and after neoadjuvant chemotherapy, prior to surgery. Four retrospectively determined grades of response at mammography included complete, mammographic (decreased size and/or density), stable disease, or progressive disease. RESULTS: In 95 fully assessable patients, grade of response to chemotherapy was complete in eight (9%), mammographic in 78 (82%), stable disease in seven (7%), and progressive disease in two (2%). Before and after treatment, respectively, 64 (67%) and 20 (21%) masses were greater than 2 cm in bidimensional diameter. Response was not complete in any of the 44 (46%) cases of microcalcifications. At histologic examination after surgery in 95 fully assessable patients, five of eight patients with complete response were found to have residual tumor (three with an invasive component); eight were found to have no residual tumor (response in three was complete; in four, mammographic; and in one, stable disease). CONCLUSION: Whereas mammograms in most patients showed some response to chemotherapy, prediction of pathologic outcome was not possible.

Antineoplastic Agents↗
PubMed1993

Case report: imaging of widespread plexiform neurofibromatosis.

Although the cutaneous, bony and retroperitoneal appearances of peripheral von Recklinghausen neurofibromatosis are well known, involvement of intra-abdominal organs and of the mediastinum is less well recognised. We present the case of a woman with peripheral neurofibromatosis who presented with loin pain. In addition to cutaneous neurofibromas, plexiform neurofibromas were present in the mediastinum, liver, mesentery and psoas muscles.

Adult↗
PubMed1992

Magnetic resonance behaviour of lipiodol.

Lipiodol is a frequently used contrast agent for lymphangiography and more recently has been used in the investigation of hepatoma. We describe the magnetic resonance characteristics of lipiodol using a Siemens 1.5 T Magnetom with reference to the appearance and behaviour of lipiodol in abdominal lymphadenopathy. The characteristics described differ from previously published reports.

Adult↗
PubMed1992

Measurement of tibial torsion--a new technique applicable to ultrasound and computed tomography.

A new method for measuring tibial torsion is described which can be applied to both ultrasound (US) and computed tomography (CT). The method has been validated in dry tibiae by comparison with direct measurements and with Jend's established CT method. In clinical practice a good statistical level of agreement has been demonstrated between the values obtained from US and CT scans. Both compared well with values obtained using Jend's CT technique. The use of US avoids exposure to radiation and is therefore suited to studying young subjects and controls and making repeat measurements.

Bone Diseases↗
PubMed1992

The role of 3D CT in the assessment of acetabular fractures.

A total of 16 patients with acetabular fractures were evaluated by plain radiography, axial computed tomography (CT) and three dimensional (3D) CT. It was possible to classify the fracture type in each case from the plain radiographs alone. Axial CT gave additional detail in certain areas, notably the region of the teardrop, the obturator foramen and the acetabular roof. Intra-articular and impacted roof fragments and associated soft tissue injuries were also shown. 3D CT provided the best and most easily interpreted overall assessment of the fractures. In addition to projections equivalent to the plain radiographs, two other views were of particular clinical value in demonstrating surgically inaccessible areas, namely the view of the pelvis from above and the view of the inner aspect of the fractured hemipelvis. However, fracture lines demonstrated on plain radiographs and axial CT were not always apparent on the 3D CT scans. Although 3D CT is a valuable addition to the imaging of acetabular fractures, it is not a substitute for good quality plain radiography and analysis of the axial CT images.

Acetabulum↗
PubMed1991

Depression of iron uptake into erythrocytes in mice by treatment with the combined benzene metabolites p-benzoquinone, muconaldehyde and hydroquinone.

Using radio-iron uptake into erythrocytes as a measure of hematopoiesis, it was demonstrated that p-benzoquinone (BQ) and muconaldehyde (MUC) are potent inhibitors of bone marrow function in female mice. These two benzene metabolites reduced iron uptake at dosages of less than 5-6 mg kg-1. The combination of MUC and hydroquinone (HQ) (100 mg kg-1) was additive, reducing iron incorporation to an extent that was the sum of the effect of each chemical given alone. The combined effect of MUC and BQ was significantly less than additive, demonstrating antagonism in the response. Multiple regression was used to study the contributions of the components of binary mixtures of the benzene metabolites (METAB). Data obtained from standard curves of METAB and their mixtures are separable in regression analysis. Thus, for zero interaction of METAB, the responses would be simply additive, while positive and negative interaction would indicate synergy and antagonism, respectively. T-testing of the data resulted in non-significant values for the mixture MUC + HQ, indicating zero interaction and an additive response. The negative t-values obtained for the mixture MUC + BQ, however, indicate negative interaction or an antagonistic response. Since mutually exclusive agents share the same binding sites and occupation of a site by one agent excludes its occupation by another, they cannot interact in producing the effect; combinations of these agents show zero interaction and are simply additive. This suggests that HQ and MUC are mutually exclusive and share the same binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehydes↗
PubMed1991

A comparison of CT and MRI in the assessment of the pituitary and parasellar region.

We have carried out a prospective study to compare high resolution thin slice, contrast-enhanced, axial computed tomography (CT) with unenhanced magnetic resonance imaging (MRI) at 1.5T in the assessment of the pituitary and parasellar region. Forty patients with suspected pituitary disease presenting to an endocrine unit were studied. MRI was superior to CT for the identification of the posterior pituitary and pituitary stalk and was better at showing the cystic nature of tumours. Visualization of the optic chiasm and assessment of displacement of the optic chiasm and the carotid arteries were also better with MRI. CT was equally good at showing cavernous sinus displacement or invasion, sphenoid sinus invasion and erosion of the floor of the sella turcica and was the only technique able to show calcification of the gland. More focal abnormalities were seen in the pituitary gland with CT than with unenhanced MRI, but there was a higher false positive rate for microadenoma detection with CT. All the scans were interpreted separately by three observers, two radiologists and one clinician. The percentage agreement between the observers for the identification of pituitary and parasellar structures was better for MRI than for CT and the clinician in particular found interpretation of the MR images easier. MRI thus not only gives more information overall than CT but it is a more reliable technique between different observers for the assessment of the pituitary and parasellar region.

Aged↗
PubMed1991

Computed tomography in malignant external otitis.

Malignant external otitis is a severe infection of the external auditory meatus occurring predominantly in diabetics and usually caused by Pseudomonas aeruginosa. The infection may spread along several routes: directly by bony erosion into the adjacent mastoid bone, anteriorly into the parotid gland and temporomandibular joint and inferiorly into the soft tissues of the infratemporal fossa. We present four cases of malignant external otitis that illustrate the typical patterns of spread of this disease and the role that radiology, and in particular computed tomography, plays in its diagnosis and management.

Aged↗
PubMed1990

Limb shortening secondary to complications of vascular cannulae in the neonatal period.

Four cases of limb shortening presenting in childhood are described. All four children had been managed in a neonatal intensive care unit and had developed complications following the insertion of intravascular cannulae. In two, lower limb shortening and deformity were secondary to direct epiphyseal damage following extravasation of calcium or dextrose from a peripheral venous line. In the other two, forearm shortening followed ischaemia, secondary to either radial artery thrombosis from a radial artery cannula or spasm of the brachial artery following extravasation from a venous cannula in a neonate who also had a radial artery cannula. These cases highlight an important complication of the use of vascular cannulae in neonates and the problems this may pose to the orthopaedic surgeon.

Arm↗
PubMed1990

Interactive inhibition of erythroid 59Fe utilization by benzene metabolites in female mice.

Using radioiron uptake into erythrocytes as a measure of hematopoiesis, it was demonstrated that benzene inhibited bone marrow function in female mice. Hydroquinone was marginally effective, but the inhibition occurred only at the highest dose tested (100 mg/kg). The combination of phenol and hydroquinone was more effective in reducing erythrocyte production than either chemical given alone. Catechol given alone was not inhibitory but when phenol was added to catechol, erythropoiesis was suppressed, as observed for the phenol and hydroquinone combination. It appears that benzene toxicity may be the result of cooperative inhibitory effects produced by its metabolites.

Animals↗
PubMed1990

Scintigraphy in the assessment of anterior knee pain.

Sixty knees presenting with chronic anterior pain were investigated. A diffusely increased uptake indicated sympathetically mediated pain provided other diagnoses such as synovitis or widespread arthrosis were excluded. Focal uptake was not specific to any one condition, but could occur in chondromalacia patellae or recent dislocations. However, the commonest appearance found in chondromalacia patellae was a normal scan. A characteristic scintigraphic appearance in symptomatic postpatellectomy knees, which has not been previously reported, was increased uptake in the femoral groove. In all the cases where no clinical or arthroscopic diagnosis was made, the bone scan was normal. The use of radioisotope scintigraphy is recommended in the problem knee presenting with anterior pain.

Adolescent↗
PubMed1988

The role of transvaginal ultrasound in the assessment of the female pelvis.

Transabdominal ultrasound of the female pelvis has been compared with transvaginal ultrasound, using a 7.5 MHz transducer, in 80 women. Transvaginal ultrasound required less patient time and was preferred in 56% of patients. Image quality was superior in 72% of cases, and visualisation of the pelvic organs was equivalent with each technique. Transabdominal ultrasound gives a more global view of the pelvis, and is of more value in assessing large pelvic masses. Transvaginal ultrasound is of more value in assessing early pregnancy, ectopic pregnancy, ovarian abnormalities, and for visualising the ovaries following hysterectomy.

Abdomen↗