Biomedical subjects

B D Tom

Publications and source records attributed to B D Tom.

10 recordsLinked to original sources

PubMed2004

Contrast-enhanced MR angiography for carotid disease: diagnostic and potential clinical impact.

OBJECTIVE: To compare contrast-enhanced MR angiography (CEMRA) with intra-arterial digital subtraction angiography (DSA) for evaluating carotid stenosis. METHODS: A total of 167 consecutive symptomatic patients, scheduled for DSA following screening duplex ultrasound (DUS), were prospectively recruited to have CEMRA. Three independent readers reported on each examination in a blinded and random manner. Agreement was assessed using the Bland-Altman method. Diagnostic and potential clinical impact of CEMRA was evaluated, singly and in combination with DUS. RESULTS: CEMRA tended to overestimate stenosis by a mean bias ranging from 2.4 to 3.8%. A significant part of the disagreement between CEMRA and DSA was directly caused by interobserver variability. For detection of severe stenosis, CEMRA alone had a sensitivity of 93.0% and specificity of 80.6%, with a diagnostic misclassification rate of 15.0% (n = 30). More importantly, clinical decision-making would, however, have been potentially altered only in 6.0% of cases (n = 12). The combination of concordant DUS and CEMRA reduced diagnostic misclassification rate to 10.1% (n = 19) at the expense of 47 (24.9%) discordant cases needing to proceed to DSA. An intermediate approach of selective DUS review resulted in a marginally worse diagnostic misclassification rate of 11.6% (n = 22) but with only 6.8% of discordant cases (n = 13). CONCLUSIONS: DSA remains the gold standard for carotid imaging. The clinical misclassification rate with CEMRA, however, is acceptably low to support its safe use instead of DSA. The appropriateness of combination strategies depends on institutional choice and cost-effectiveness issues.

Aged↗

PubMed2002

Pulsatile ocular blood flow: the effect of the Valsalva manoeuvre in open angle and normal tension glaucoma: a case report and prospective study.

AIM: A case of severe normal tension glaucoma is reported in a trumpet player, along with a study investigating the association between glaucoma and raised intrathoracic pressure, using measurements of pulsatile ocular blood flow (POBF). METHODS: Three patient groups were studied; normals (n = 34), untreated primary open angle glaucoma (POAG) (n = 20), and untreated normal tension glaucoma (NTG) (n = 22), with a total of 76 patients who underwent measurements of POBF using the OBF pneumotonometer at rest and while forcibly exhaling through a mouthpiece connected to a mercury manometer (30 mm Hg) (Valsalva manoeuvre). RESULTS: POBF fell during Valsalva in all groups with the greatest predictor being the resting value of POBF. There was no evidence of significant differences in the mean change in POBF occurring during the Valsalva manoeuvre for the three groups studied before or after adjusting for the sex, the resting POBF, and the resting IOP of the patients (p = 0.294 and p = 0.542, respectively). However, statistically significant associations were found between the change in POBF and sex (p = 0.049), resting POBF (p<0.0001) and resting IOP (p = 0.032). Males had a greater drop, on average, in POBF during Valsalva manoeuvre than females after adjusting for the other factors. Additionally, there was a significant difference in the mean change in IOP during Valsalva for the three groups (p = 0.002), with the difference occurring between the normal and POAG groups (p<0.005). The POAG group had, on average, a drop in IOP during Valsalva, while the other two groups had an increase in IOP. Also noted was a significant difference in the distributions of the risk factors among the three groups (p = 0.002). CONCLUSIONS: This study demonstrates no difference between groups with respect to resting or Valsalva POBF, but does demonstrate a possible trend with respect to IOP, with a drop in IOP occurring during Valsalva in the POAG group. There is, however, much variability in the data left unexplained by our models. Thus, unfortunately, we cannot advise our trumpet player whether his NTG is directly related to his trumpet playing.

Age Factors↗

PubMed2001

Hyperuricemia, gout, and renal function after liver transplantation.

BACKGROUND: Hyperuricemia is a recognized complication of renal and cardiac transplantation, but the development of hyperuricemia and gout following liver transplantation have received less attention. We have retrospectively assessed the prevalence of hyperuricemia in 134 consecutive liver transplant recipients. RESULTS: Forty-seven percent of the liver transplant recipients studied had hyperuricemia. Serum creatinine was higher in hyperuricemic than in nonhyperuricemic patients. Peak uric acid correlated significantly with corresponding serum creatinine (rs=0.694). Only 6% developed gout. All the patients with gout and 10 hyperuricemic patients with renal impairment but without gout were treated with allopurinol. Over a median period of 3 months, mean serum creatinine fell from 177 micromol/l to 160 micromol/l (P=0.01), without change in type or dose of immuno-suppression. CONCLUSIONS: There is an important association between liver transplantation and hyperuricemia. Treatment with allopurinol results in a significant reduction in serum creatinine in patients with gout and in those with hyperuricemia and renal impairment.

Adult↗

PubMed2001

Magnetic resonance imaging of the wrist: diagnostic performance statistics.

AIM: To review the published diagnostic performance statistics for magnetic resonance imaging (MRI) of the wrist for tears of the triangular fibrocartilage complex, the intrinsic carpal ligaments, and for osteonecrosis of the carpal bones. MATERIALS AND METHODS: We used Medline and Embase to search the English language literature. Studies evaluating the diagnostic performance of MRI of the wrist in living patients with surgical confirmation of MR findings were identified. RESULTS: We identified 11 studies reporting the diagnostic performance of MRI for tears of the triangular fibrocartilage complex for a total of 410 patients, six studies for the scapho-lunate ligament (159 patients), six studies for the luno-triquetral ligament (142 patients) and four studies (56 patients) for osteonecrosis of the carpal bones. CONCLUSIONS: Magnetic resonance imaging is an accurate means of diagnosing tears of the triangular fibrocartilage and carpal osteonecrosis. Although MRI is highly specific for tears of the intrinsic carpal ligaments, its sensitivity is low. The diagnostic performance of MRI in the wrist is improved by using high-resolution T2* weighted 3D gradient echo sequences. Using current imaging techniques without intra-articular contrast medium, magnetic resonance imaging cannot reliably exclude tears of the intrinsic carpal ligaments. Hobby, J. L. (2001). Clinical Radiology, 56, 50-57.

Carpal Bones↗

PubMed2001

Prognostic variables in canine multicentric lymphosarcoma.

This paper presents the results of a prospective study to investigate the prognostic value of clinical staging, histological grading, immunophenotype, mitotic count and average numbers of argyrophilic nucleolar organiser region counts in dogs with multicentric lymphosarcoma treated with a standard chemotherapy protocol comprising vincristine, cyclophosphamide and prednisolone. Forty-nine dogs were treated according to the study protocol. Univariate and multivariate analysis with regression modelling was used to evaluate the prognostic importance of patient and tumour variables upon tumour response and relapse-free survival. Thirty-seven dogs (76 per cent) achieved a complete remission, seven (14 per cent) a partial remission and five (10 per cent) failed to respond to treatment. None of the variables examined had a statistically significant effect upon tumour response. Tumour immunophenotype was the only parameter found to have a significant influence on patient survival, the hazard ratio for T-cell versus B-cell immunophenotype was 3.99 with 95 per cent confidence interval from 1.399 to 11.372, P = 0.035.

Animals↗

PubMed2001

MR imaging of the wrist: effect on clinical diagnosis and patient care.

PURPOSE: To evaluate the effect of magnetic resonance (MR) imaging of the wrist on clinicians' diagnoses, diagnostic certainty, and patient care. MATERIALS AND METHODS: A controlled observational study was performed. Referring clinicians completed questionnaires about diagnosis and intended management before and after wrist MR imaging. One hundred eighteen consecutive patients referred for MR imaging of the wrist were recruited from the MR imaging units at a regional teaching hospital and a large district general hospital. The main measures were changes in the clinicians' leading and subsidiary diagnoses after MR imaging, their certainty in these diagnoses, and changes in intended patient care. RESULTS: Questionnaires were incorrectly completed for five patients, questionnaires were not returned for three, appointments were canceled for 10, and two could not tolerate the MR examination. Complete follow-up data were available for 98 patients. The clinical diagnosis changed in 55 of 98 patients; in the remaining 43 patients, diagnostic certainty increased in 23. Clinicians reported that MR imaging had substantially improved their understanding of the disease in 67 of 98 patients. The care plan changed in 45 of 98 patients, with a shift away from surgical treatment. Twenty-eight patients were discharged without further investigation. MR imaging was similarly effective in the regional teaching center and the district general hospital. CONCLUSION: MR imaging of the wrist influences clinicians' diagnoses and management plans.

Humans↗

PubMed2000

Who should manage primary retinal detachments?

PURPOSE: To determine whether the outcome of primary retinal reattachment surgery in a subregion is improved by surgery being performed in a specialist vitreoretinal unit (VRU). METHODS: A subregional, population-based, retrospective audit cycle of primary retinal reattachment surgery was conducted by independent investigators. The subregion was defined as the catchment area of a teaching hospital (TH) with a specialist VRU and three neighbouring district general hospitals (DGHs). During the initial audit period (January 1989 to December 1990), 142 cases were treated at all four hospitals: TH/VRU (83), DGH-A (15), DGH-B (13), and DGH-C (31). Policy changes after the initial audit led to primary retinal reattachment surgery being predominantly performed by the VRU. During the re-audit period (September 1995 to August 1997), 160 cases were treated at two hospitals: VRU (148) and DGH-C (12). The outcome measure employed was complete retinal reattachment after a single procedure with a minimum follow-up of 12 months. RESULTS: The success rate for primary retinal reattachment surgery in the subregion improved from 76.1% to 88.8% (p = 0.006) following the policy changes. The success rate of the vitreoretinal specialists in the VRU (90%) was greater than the general ophthalmologists in the DGHs (ranging from 47% to 77%), despite case selection by the general ophthalmologists. The number of cases treated by the VRU increased by 156% in the 6.5 year interval between the two audits due to a widespread change in the model of care for primary retinal detachments (both within and outside the subregion). During the re-audit period, the VRU treated 348 primary retinal detachments (including referrals from outside the subregion), achieving a success rate of 86.8% with a single procedure and 97.4% with further surgery. This primary success rate included 35 cases (10%) treated by vitrectomy with silicone oil tamponade who did not undergo silicone oil removal. CONCLUSIONS: The outcome of primary retinal reattachment surgery can be improved if surgery is performed by a specialist VRU. It is suggested that the current standard for retinal reattachment with a single procedure should be set in the region of 85% to 90%. Changing the model of care so that primary retinal reattachment surgery is predominantly performed by a specialist VRU has important resource implications.

England↗

PubMed2000

Communication of doubt and certainty in radiological reports.

We have investigated the reliability of communication of uncertainty in radiological reports. The 18 most commonly used verbal expressions of probability were identified from a series of radiological reports. 11 clinicians (three radiologists, three rheumatologists and five orthopaedic surgeons) recorded the probability that they ascribed to each of the 18 expressions using visual analogue scales. Each subject was re-tested on four occasions at least 1 week apart. The results were analysed to assess reproducibility within and between individuals. We found considerable variation in the probabilities assigned to many commonly used expressions between subjects, and between repeated testing of the same subject. Some expressions were rated much more consistently than others. "Absent", "excludes", "unlikely", "probable", "certain" and "definite" were the most consistently rated expressions. We have identified a potential source of misunderstanding in radiological reports owing to differences in interpretation of expressions used by radiologists and referring clinicians.

Diagnostic Services↗

PubMed2000

Changes in tumorigenesis- and angiogenesis-related gene transcript abundance profiles in ovarian cancer detected by tailored high density cDNA arrays.

BACKGROUND: Complementary DNA array analysis of gene expression has a potential application for clinical diagnosis of disease processes. However, accessibility, affordability, reproducibility of results, and management of the data generated remain issues of concern. Use of cDNA arrays tailored for studies of specific pathways, tissues, or disease states may render a cost- and time-effective method to define potential hallmark genotype alterations. MATERIALS AND METHODS: We produced a 332-membered human cDNA array on nylon membranes tailored for studies of angiogenesis and tumorigenesis in reproductive disease. We tested the system for reproducibility using a novel statistical approach for analysis of array data and employed the arrays to investigate gene expression alterations in ovarian cancer. RESULTS: Intra-assay analysis and removal of agreement outliers was shown to be a critical step prior to interpretation of cDNA array data. The system revealed highly reproducible results, with intermembrane coefficient of reproducibility of +/- 0.98. Comparison of placental and ovarian sample data confirmed expected differences in angiogenic profiles and tissue-specific markers, such as human placental lactogen (hPL). Analysis of expression profiles of five normal ovary and four poorly differentiated serous papillary ovarian adenocarcinoma samples revealed an overall increase in angiogenesis-related markers, including vascular endothelial growth factor (VEGF) and angiopoietin-1 in the diseased tissue. These were accompanied by increases in immune response mediators (e.g. HLA-DR, Ron), apoptotic and neoplastic markers (e.g. BAD protein, b-myb), and novel potential markers of ovarian cancer, such as cofilin, moesin, and neuron-restrictive silencer factor (REST) protein. CONCLUSIONS: In-house production of tailored cDNA arrays, coupled to comprehensive analysis of resulting hybridization profiles, provides an accessible, reliable, and highly effective method of applying array technology to study disease processes. In the ovary, abundance of specific tumor markers, increased macrophage recruitment mediators, a late-stage angiogenesis profile, and the presence of chemoresistance-related markers distinguished normal and advanced ovarian cancer tissue samples. Detection of such parallel changes in pathway- and tissue-specific markers may prove a hallmark ready for application in reproductive disease diagnostic and therapeutic developments.

Biomarkers, Tumor↗

PubMed1999

Further evidence for an association between non-insulin-dependent diabetes mellitus and chronic hepatitis C virus infection.

Non-insulin-dependent diabetes mellitus (NIDDM) may be associated with chronic hepatitis C virus (HCV) infection. This was studied further in two parts. First, 1,151 patients with HCV-related cirrhosis and 181 patients with hepatitis B virus (HBV)-related cirrhosis, well matched for age, sex, and severity of cirrhosis, were reviewed retrospectively. The prevalence of diabetes mellitus was higher in HCV-related cirrhosis (23.6%) than in HBV-related cirrhosis (9.4%; odds ratio [OR], 2.78; 95% confidence interval [CI], 1.6-4.79; P =.0002). The prevalence of diabetes mellitus was associated closely with the Child-Pugh score (OR, 3.83; 95% CI, 2. 38-6.17; P <.0001) and increasing age (OR, 1.02; 95% CI, 1.00-1.03; P =.0117). Second, 235 patients with biopsy confirmed chronic HBV or HCV underwent an oral glucose tolerance test. Only 1 of 70 patients with chronic viral hepatitis without cirrhosis was diabetic. However, 31 of 127 patients with HCV-related cirrhosis (24.4%) were diabetic compared with 3 of 38 patients with HBV-related cirrhosis (7.9%, P =.0477). The major variables associated with NIDDM were cirrhosis (OR, 14.39; 95% CI, 1.91-108; P =.0096) and male sex (OR, 4.64; 95% CI, 1. 32-16.18; P =.0161). Fasting insulin levels in 30 patients with HCV-related cirrhosis and diabetes mellitus were elevated significantly, which was consistent with insulin resistance. However, acute insulin responsiveness was reduced in all patients with HCV infection and diabetes suggesting concomitant B-cell dysfunction. This study confirms an association between HCV and NIDDM.

Adult↗