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Biomedical subjects

W Taylor

Publications and source records attributed to W Taylor.

At least 37 records · Page 2Linked to original sources
PubMed2001

Factors influencing rate of Barthel Index change in hospital following stroke.

BACKGROUND AND PURPOSE: Randomized controlled trials of specific interventions in stroke rehabilitation are few. In using this study design to compare different rehabilitation interventions or different intensity of those interventions, measuring disability status at a fixed time point is one outcome option. In order for this approach to be valid, factors that might independently affect the speed of disability change have to be matched at baseline. We sought to investigate the impact of different factors on rate of disability change following stroke. METHODS: A prospective hospital-based study of consecutive patients admitted to each of three general hospitals in Wellington, New Zealand with acute stroke. Patients were assessed using the Barthel Index (BI, scored 0-20) within a few days of stroke and fortnightly until hospital discharge. Strokes were classified using the Oxfordshire Community Stroke Project classification. MAIN OUTCOME MEASURE: Barthel Index rate of change (BRC) computed from the difference between the first and last hospital BI scores divided by the time in weeks between these assessments. RESULTS: Of 104 subjects with two or more disability assessments in hospital, BRC was a mean 1.26 units per week (95% confidence interval (CI) 0.97, 1.56). The only factors significantly associated with BRC on univariate analysis were stroke type, pre-stroke Modified Rankin Scale (MRS) and pre-stroke London Handicap Score. In a general linear model analysis of covariance, stroke type (p = 0.015) and pre-stroke MRS (p < 0.001) remained significant. The mean BRC for lacunar infarcts (1.76 units per week, 95% CI 1.22, 2.30) was over three times that of total anterior circulation infarcts (0.48 units per week, 95% CI 0.20, 0.76). CONCLUSIONS: Future randomized controlled trials of rehabilitation interventions for stroke in hospitalized patients need to allow for pre-stroke level of dependence and stroke type in the study design, either excluding particular patients or ensuring even randomization of these key variables if speed of disability change is to be a valid outcome variable.

Aged↗
PubMed2001

Gamma knife surgery for treatment of central neurocytomas. Report of four cases.

The authors investigated the use of gamma knife surgery (GKS) in the treatment of central neurocytoma, a usually benign primary brain tumor of the lateral and third ventricles. Four patients with subtotally resected or recurrent central neurocytomas were retrospectively studied. The prescription isodose was 9 to 13 Gy to the 30 to 50% peripheral isodose line. Pre- and postoperative magnetic resonance (MR) images were compared to determine the volume reduction following GKS. Follow-up review included annual MR imaging and clinical evaluation by a neurosurgeon. Follow-up periods ranged from 12 to 99 months. Marked reduction in tumor size was seen in all four patients; the decrease in tumor volume for each was 48%, 72%, 81%, and 77%, respectively, at the last follow-up review. None of the four patients required additional treatment and none experienced a decline in neurological function during the follow-up period. No complications have been noted in any of these patients to date. Even though there have been few observations and follow-up time has been limited, because of the consistency of the response and the lack of observed side effects, GKS may be the treatment of choice for subtotally resected and recurrent central neurocytomas.

Adult↗
PubMed2001

Clinical presentation, radiological findings, and treatment results of coccidioidomycosis involving the spine: report on 23 cases.

OBJECT: This study was conducted to review the presentation and management of patients with coccidioidomycosis involving the spine. METHODS: The authors reviewed 23 cases of spinal coccidioidomycosis treated at their institutions. There were 20 males and three females who ranged in age from 9 to 62 years. Non-Caucasian individuals were disproportionately represented. Spinal disease was the first manifestation of disseminated coccidioidomycosis in 10 cases. Thirteen patients with meningitis, soft-tissue involvement, or pulmonary involvement developed new spinal lesions despite undergoing continued systemic therapy with amphotericin and/or fluconazole. In all patients computerized tomography and magnetic resonance imaging studies demonstrated preferential involvement of the disc spaces, vertebral bodies, and pedicles with extensive paravertebral phlegmons and retropharyngeal, mediastinal, or psoas abscesses. Despite the significant imaging findings, only four patients presented with a significant neurological deficit. Local pain or radiculopathy was the most common complaint. Twenty patients underwent invasive therapy. In five patients with prominent psoas abscesses and disc space disease, drainage was performed after inserting a percutaneous catheter. Progressive bone destruction necessitated debridement and fusion in one of these patients, and two others had poor outcomes after receiving antifungal therapy alone. Initially 15 patients underwent debridement and fusion in which instrumentation (10 cases) or bone graft alone was used (five cases). One patient worsened neurologically after surgery, and another patient required reoperation for a failed fusion and to correct progressive kyphosis. Four of the 23 patients died of complications related to fungemia. Most of the 15 surviving patients have required long-term antifungal therapy for spinal and extraspinal foci. CONCLUSIONS: Spinal coccidioidomycosis can be an aggressive disease process. Systemic antifungal therapy fails to prevent de novo spinal involvement and is usually insufficient treatment for established spinal disease.

Adolescent↗
PubMed2000

Spin correlation in t&tmacr; production from p&pmacr; collisions at radicals = 1.8 TeV

The D0 collaboration has performed a study of spin correlation in t&tmacr; production for the process t&tmacr;-->bW(+)&bmacr;W-, where the W bosons decay to enu or &mgr;nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb(-1) of sqrt[s] = 1.8 TeV p&pmacr; collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the t&tmacr; decay products. The degree of spin correlation is characterized by a correlation coefficient kappa. We find that kappa>-0.25 at the 68% confidence level, in agreement with the SM prediction of kappa = 0.88.

Journal Article↗
PubMed2000

Contrast-enhanced MR angiography in patients with carotid artery stenosis: comparison of two different techniques with an unenhanced 2D time-of-flight sequence.

Conventional time-of-flight (TOF) MR angiography (MRA) in carotid artery stenosis relies on flow-related enhancement to produce signal from vascular structures. Intravoxel phase dispersion, due to vortices, causes loss of signal and is the reason for the tendency to overestimate the degree of stenosis. In contrast-enhanced MRA, intravascular signal is mainly dependent on T1 shortening of the blood. We compared first-pass contrast-enhanced MRA (contrast-enhanced 3D gradient echo, ce3D GRE) and contrast-enhanced 2D TOF (ce2D TOF) sequences with an unenhanced 2D TOF in 13 patients with carotid artery stenosis, assessing delineation of the carotid bifurcation, enhancement of veins and grade of stenosis. The contrast-enhanced techniques produced more morphological detail, the ce3D GRE being superior to the ce2D TOF. Four carotid arteries were reclassified into lesser stenosis categories using the ce3D GRE technique. However, seven carotid arteries (27%) were rated as nondiagnostic on the ce3D GRE, mainly due to masking of the carotid bifurcation by veins. The latter can be avoided by decreasing the acquisition time; on our 1.5-T system we could achieve a minimum time of 23 s per 3D GRE. Further reduction of acquisition time would be necessary to incorporate this method into clinical routine, requiring higher-performance gradients, which are not available in many UK hospitals.

Aged↗
PubMed2000

Inhibition of lipoprotein oxidation by prenylated xanthones derived from mangostin.

Oxidative damage is thought to play a critical role in cardiovascular and other chronic diseases. This has led to considerable interest in the antioxidant activity of dietary compounds. Flavonoids have received the most attention and much is known about the structural requirements for antioxidant activity. However, little is known about the antioxidant activity of other plant derived phenolic compounds such as the xanthones. We have previously shown that the prenylated xanthone, mangostin, can inhibit the oxidation of low density lipoprotein. In order to examine the effects of structure modification on antioxidant activity of this class of compound we have prepared a number of derivatives of mangostin and tested antioxidant activity in an isolated LDL and plasma assay. The results of this study show that structural modification of mangostin can have a profound effect on antioxidant activity. Derivatisation of the C-3 and C-6 hydroxyl groups with either methyl, acetate, propane diol or nitrile substantially reduces antioxidant activity. In contrast, derivatisation of C-3 and C-6 with aminoethyl derivatives enhanced antioxidant activity, which may be related to changes in solubility. Cyclisation of the prenyl chains had little influence on antioxidant activity.

Antioxidants↗
PubMed1999

Accelerated transcription of PRPS1 in X-linked overactivity of normal human phosphoribosylpyrophosphate synthetase.

Phosphoribosylpyrophosphate (PRPP) synthetase (PRS) superactivity is an X-linked disorder characterized by gout with overproduction of purine nucleotides and uric acid. Study of the two X-linked PRS isoforms (PRS1 and PRS2) in cells from certain affected individuals has shown selectively increased concentrations of structurally normal PRS1 transcript and isoform, suggesting that this form of the disorder involves pretranslational dysregulation of PRPS1 expression and might be more appropriately termed overactivity of normal PRS. We applied Southern and Northern blot analyses and slot blotting of nuclear runoffs to delineate the process underlying aberrant PRPS1 expression in fibroblasts and lymphoblasts from patients with overactivity of normal PRS. Neither PRPS1 amplification nor altered stability or processing of PRS1 mRNA was identified, but PRPS1 transcription was increased relative to GAPDH (3- to 4-fold normal in fibroblasts; 1.9- to 2.4-fold in lymphoblasts) and PRPS2. Nearly coordinate relative increases in each process mediating transfer of genetic information from PRPS1 transcription to maximal PRS1 isoform expression in patient fibroblasts further supported the idea that accelerated PRPS1 transcription is the major aberration leading to PRS1 overexpression. In addition, modulated relative increases in PRS activities at suboptimal Pi concentration and in rates of PRPP and purine nucleotide synthesis in intact patient fibroblasts indicate that despite an intact allosteric mechanism of regulation of PRS activity, PRPS1 transcription is a major determinant of PRPP and purine synthesis. The genetic basis of disordered PRPS1 transcription remains unresolved; normal- and patient-derived PRPS1s share nucleotide sequence identity at least 850 base pairs 5' to the consensus transcription initiation site.

Allosteric Regulation↗
PubMed1999

Study of chromosome 12 copy number in breast cancer using fluorescence in situ hybridization.

Trisomy 12 is the most frequent numerical chromosomal abnormality reported in chronic lymphocytic leukemia (CLL). Its significance in other cancers, however, has not been extensively investigated until recently. Less than 20 cases of polysomy for chromosome 12 have been studied thus far. The most recent data in the literature suggest that gain of chromosome 12 may be a recurrent and sometimes early event in breast carcinogenesis. To test the hypothesis that a subset of breast cancer may be characterized by chromosome 12 trisomy, we conducted a retrospective study of 40 specimens. Of these, ten were stage I, ten were stage II, ten were stage III, and ten were stage IV. Out of the total sample, 12 cases (30%) were found to be presumably trisomic, if a conservative cutoff point of greater than or equal to 15% cells with three signals is adopted. Furthermore, some, but not all, of the 12 cases were found to be likely triploid, when data from a control chromosome 17 probe were taken into account. Thus, our data support the hypothesis that a subset of breast cancer exists which is characterized by an abnormal copy of chromosome 12, in either a diploid or a triploid background.

Breast Neoplasms↗
PubMed1999

Abnormal chromosome 8 copy number in stage I to stage IV breast cancer studied by fluorescence in situ hybridization.

To test the hypothesis that the frequency of abnormal chromosome 8 copy number increases with the severity of the disease as defined by an increase in clinical stage, we conducted a fluorescence in situ hybridization (FISH) study of a sample of 42 breast cancer specimens utilizing a protocol that was optimized by our laboratory. Cytogenetic results, obtained from blinded analyses of archival specimens, demonstrated that the higher clinical stages (i.e., stages III and IV) yield higher frequencies of abnormal chromosome 8 copy number. Specifically, 45.45% and 50% of the stage I and stage II cases, respectively, were abnormal, whereas 63.64% and 60% of the stage III and stage IV cases, respectively, were abnormal for chromosome 8 copy number. The overall frequency of abnormal chromosome 8 copy number was 54.76% (23 of 42 tumors studied). When the results of a control probe were taken into account, 34.78% (8 of 23) of the abnormal cases were trisomic, whereas the remaining cases were likely triploid. Thus, the present data not only established that chromosome 8 trisomy is a recurrent finding in breast cancer, but also confirmed a higher frequency of occurrence of abnormal chromosome 8 copy number with the higher clinical stages. Future experiments utilizing additional specimens in this laboratory and from other laboratories are necessary to confirm and extend the findings of the present study.

Aneuploidy↗
PubMed1999

Validity of self-assessment of pubertal maturation in African American and European American adolescents.

PURPOSE: To evaluate interobserver reliability of physician assessments of pubertal maturation and to evaluate the validity of self-assessment compared to physician assessments of pubertal maturation by girls in a multiethnic sample. METHODS: The study design is descriptive. A total of 107 8-17-year-old healthy volunteers from settings with large minority populations in the Houston metropolitan area were recruited for a study on adolescents' energy needs. The two outcome measures were interobserver reliability between two physicians' assessments of breast and pubic hair, and the self-assessment of breast and pubic hair maturation compared to physicians' assessments. RESULTS: The kappa coefficient for physician interobserver agreement for breast maturation was 0.5. The kappa coefficient for physician interobserver agreement for assessment of pubic hair was 0.79. The kappa coefficient for the validity of self-assessment of breast development was 0.34, and that for self-assessment of pubic hair was 0.37. CONCLUSION: Interobserver agreement for physician assessment of breast maturation was low and self-assessment of breast maturation was not reliable in this group of adolescent girls. However, whereas physician interobserver agreement for pubic hair was good, self-assessment of pubic hair maturation was not reliable in this group of adolescent girls.

Adolescent↗
PubMed1999

Leptin levels are suppressed in primary aldosteronism.

Primary aldosteronism is associated with hypertension secondary to salt and water retention, hypokalemia and impaired insulin secretion with glucose intolerance in some patients. The secretion of leptin, a hormone produced by adipocytes, may be altered by reduced insulin secretion in primary aldosteronism. We measured plasma leptin approximately 3 months before and 3 months after curing of primary aldosteronism in 18 patients (12 male, 6 female, body mass index 29.1+/-4.4, mean +/- SD). Patients were treated by unilateral laparoscopic adrenalectomy to remove an aldosterone-producing adenoma. There was a 46% postoperative increase in plasma leptin concentrations from 6.65+/-0.81 to 9.68+/-1.50 ng/ml (P=0.004), despite a non-significant fall in body mass index. Plasma leptin was noted to increase after adrenalectomy in 16 of the 18 patients. The patients also had improved blood pressure and a significant increase in plasma potassium post-operatively. It is proposed that increased insulin secretory capacity associated with correction of negative potassium balance may account for the increase in plasma leptin after curing primary aldosteronism. Further studies are indicated to identify the mechanism of plasma leptin suppression in primary aldosteronism.

Adult↗
PubMed1999

Current use and timing of spinal surgery for management of acute spinal surgery for management of acute spinal cord injury in North America: results of a retrospective multicenter study.

OBJECT: A multicenter retrospective study was performed in 36 North American centers to examine the use and timing of surgery in patients who have sustained acute spinal cord injury (SCI). The study was performed to obtain information required for the planning of a randomized controlled trial in which early and late decompressive surgery are compared. METHODS: The records of all patients aged 16 to 75 years with acute SCI admitted to 36 centers within 24 hours of injury over a 9-month period in 1994 and 1995 were examined to obtain data on admission variables, methods of diagnosis, use of traction, and surgical variables including type and timing of surgery. A total of 585 patients with acute SCI or cauda equina injury were admitted to participating centers, although approximately half were ultimately excluded because they did not meet inclusion criteria. Common causes for exclusion were late admission, age, gunshot wound, and absence of signs of compression on imaging studies. Thus, only approximately 50% of patients with acute SCI would be eligible for inclusion in a study of acute decompressive surgery. Although all patients underwent computerized tomography (CT) scanning, only 54% underwent magnetic resonance imaging, and CT myelography was performed in only 6%. Complete neurological injuries (American Spinal Injury Association Grade A) were present in 57.8%. Traction was applied in only 47% of patients who sustained cervical injury, in whom decompressive traction was successful in only 42% of cases. Neurological deterioration occurred in 8.1% of cases after traction. Surgery was performed in 65.4% of patients. The timing of surgery varied widely: less than 24 hours postinjury in 23.5%, between 25 and 48 hours postinjury in 15.8%, between 48 and 96 hours in 19%, and more than 5 days postinjury in 41.7% of patients. CONCLUSIONS: These data indicate that although surgery is commonly performed in patients with acute SCI, one third of cases are managed nonoperatively, and there is very little agreement on the optimum timing of surgical treatment. The results of this study confirm the need for a randomized controlled trial to assess the optimum timing of decompressive surgery in SCI.

Acute Disease↗