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Biomedical subjects

D J Manton

Publications and source records attributed to D J Manton.

At least 19 recordsLinked to original sources
PubMed2000

Combined proton MR spectroscopy and dynamic contrast enhanced MR imaging of human intracranial tumours in vivo.

A study was undertaken to determine if the vascular characteristics measured by dynamic contrast-enhanced magnetic resonance imaging (primarily permeability surface area product and extracellular-extravascular tissue volume fraction) would be beneficial in explaining the inter-lesion metabolic heterogeneity displayed by human intracranial tumours. Magnetic resonance spectroscopy was carried out using a single-voxel STEAM sequence and dynamic imaging was carried out using a combination of pre-contrast proton density-weighted FSPGR images (to remove the influence of native tissue T1), bolus injection of Gd-DTPA and subsequent T1-weighted FSPGR dynamic imaging. A two-compartment pharmacokinetic model was employed to determine vascular characteristics. Results obtained from 12 meningiomas suggest a possible correlation between the level of lipids/macromolecules and permeability surface area product, although the confounding issue of extra-voxel contamination arising from lipids in the scalp and skull marrow cannot be ruled out in the more superficial lesions. Results obtained from 11 gliomas (four low and seven high grade) demonstrate that permeability surface area product is not specific for the range of vascular characteristics and metabolite profiles observed in gliomas and is therefore unable to explain metabolic heterogeneity in these lesions.

Brain Neoplasms↗
PubMed1999

Histological analysis of the uterine junctional zone as seen by transvaginal ultrasound.

OBJECTIVE: This study aimed to investigate the histology of the subendometrial halo, the junctional zone between the endometrium and myometrium. METHODS: Thirteen ex vivo uteri removed for treatment of menorrhagia were studied. In each case, the subendometrial halo, as seen by transvaginal ultrasound, was marked using a Nottingham breast location biopsy needle. A standard histological examination was performed. Full thickness blocks of the anterior uterine wall were taken and standard serial 5-micron tissue sections were prepared from each block. Subsequent morphometric analysis followed staining with Feulgen reagent, using a CAS 200D quantitative image analysis system. Additionally, anti-CD31, an antibody stain for vascular endothelium, was used. RESULTS: The histological examination showed the subendometrial halo to consist of apparently normal myometrium. Morphometric analysis demonstrated a greater total nuclear area in the subendometrial halo than the outer myometrium, but no difference in individual nuclear size between the two zones. CD31 stained a greater total area in the inner myometrium. CONCLUSIONS: These results suggest that the subendometrial halo is a distinct compartment of the myometrium comprising tightly packed muscle cells with an increased vascularity. Such architecture would increase the density of this tissue layer, altering its acoustic impedance, and account for its echopenic appearance on ultrasound.

Adult↗
PubMed1999

Ultrasound evaluation of the uterine zonal anatomy during in-vitro fertilization and embryo transfer.

This study was designed to establish if ultrasound could detect differences in uterine zonal anatomy between conception and non-conception in-vitro fertilization (IVF)/embryo transfer cycles. A transvaginal ultrasound scan was performed on the day of down regulation (D0), on day 8 of ovulation induction (D8), on the day of human chorionic gonadotrophin (HCG) injection, at the time of oocyte retrieval, and at embryo transfer. Thicknesses of endometrium, junctional zone, myometrium and full thickness of the uterus were recorded for every patient and comparisons made at all the assessment points. Differences between measurements on D0 and all other measurements (temporal changes) and between every subsequent measurement (dynamic changes) were also compared. There were no statistically significant differences in endometrial thickness between pregnant and non-pregnant groups at any time. The diameter of the uterus increased during therapy and was significantly greater in the pregnant subset at the time of HCG injection, oocyte retrieval and embryo transfer (P < 0.02, 0.03 and 0.02 respectively). The myometrium was significantly thicker in the pregnant group on D0, on D8 and at HCG administration (P < 0.03, 0.004 and 0.02). There was a decrease in junctional zone thickness in both groups during the first week of ovulation induction, and on D8 the junctional zone in pregnant patients was significantly thinner (P < 0.04). The junctional zone became significantly thicker at embryo transfer in the pregnant group (P < 0.01). This was confirmed by significant temporal and dynamic changes at the time of oocyte retrieval and embryo transfer (P < 0.01, 0.0001 and P < 0.05, 0.01 respectively). In the patients who did not conceive, changes in the junctional zone were less pronounced. In conclusion, it was not possible to predict the likelihood of pregnancy from endometrial thickness at any time during the IVF cycle, but changes occurred in other uterine layers that were more pronounced in conception cycles. The responsiveness of the junctional zone seems to be associated with implantation, and its measurements at the time of downregulation and embryo transfer can be used to predict treatment outcome.

Adult↗
PubMed1996

Proton MR T2 maps correlate with the citrate concentration in the prostate.

A significant correlation between water T2 relaxation time and citrate concentration in the normal prostate is demonstrated using spatially localized spectroscopy and water T2 maps. These data imply that MR images may be used to infer the concentration of citrate at high spatial resolution. Preliminary results in patients demonstrate that this relationship is maintained in benign prostatic hyperplasia (BPH) and prostatic carcinoma. The determination of citrate concentration and water T2 may aid the differentiation of prostate carcinoma from BPH and normal tissue.

Adult↗
PubMed1996

Quantification of citrate concentration in the prostate by proton magnetic resonance spectroscopy: zonal and age-related differences.

A commercial phased-array multicoil was used to acquire water-suppressed localized proton spectra of the two major anatomical regions of the prostate. The signal-to-noise ratio and spectral resolution allowed identification of peaks from choline and creatine, as well as a major peak from citrate. Quantification of the citrate peak using experimentally determined relaxation parameters with tissue water as an internal concentration reference revealed a marked variability between different volunteers. Nevertheless, in each case, the citrate concentration was up to fourfold greater in the peripheral zone than in the central gland. Furthermore, the difference in citrate concentration between these two regions was positively correlated with the subjects age. The results indicate a consistent difference in cellular function between the major anatomical regions within the prostate and may have important consequences for the application of magnetic resonance spectroscopy to the diagnosis of prostatic pathology.

Adult↗
PubMed1995

Determination of proton metabolite concentrations and relaxation parameters in normal human brain and intracranial tumours.

Quantitative proton spectroscopic studies were performed on 39 volunteers and 16 patients with intracranial tumours. Estimates of T2 were obtained in white matter, grey matter, cerebellum, astrocytomas and meningiomas; T1 was determined in white matter only. White matter values of T2 for trimethylamines, creatine and N-acetyl aspartate (NAA) were 309 +/- 84, 195 +/- 41 and 369 +/- 124 ms, respectively (mean +/- SD, n = 20). Metabolite concentrations in white matter were 2.0 +/- 0.4 mumol/g wet weight for trimethylamines, 7.3 +/- 1.1 for creatine and 11.4 +/- 1.4 for NAA. The mean concentrations of creatine and NAA in grey matter and all of three metabolites in cerebellum were greater than those in white matter. Tumour spectra were characterized by increased trimethylamines, reduced creatine and NAA and occasionally the presence of lactate. Meningiomas were further characterized by the presence of alanine. The mean T2 and concentration of trimethylamines in tumours was significantly greater than in normal brain. Creatine and NAA concentrations were decreased in all tumours. The longer T2 of trimethylamines and presence of alanine in meningiomas indicate that important differences exist in membrane and glucose metabolism within these tumours when compared to either astrocytomas or normal brain tissue.

Aspartic Acid↗
PubMed1995

Pit and fissure sealants: another major cornerstone in preventive dentistry.

Despite dramatic reductions in caries in fluoridated communities, the disease continues to occur during childhood and adolescence and there is a sustained caries susceptibility of pits and fissures. Pit and fissure sealants have been available to the dental profession for the past two decades. Closely following community water fluoridation, this use of adhesive technology is now recognized as a major cornerstone of modern preventive dentistry. However, the technique appears to have been slow in implementation by the dental profession. Recent expanded utilization of sealants in the public sector, particularly in Victoria, has increased the awareness of the procedure amongst the public and is heightening demand. A review of the pertinent literature and current trends in utilization of sealants is presented. The case is made for expanded utilization of sealants in both the public and private sectors of dental health care delivery in Australia.

Adolescent↗