Biomedical subjects

R P Reid

Publications and source records attributed to R P Reid.

8 recordsLinked to original sources

PubMed2001

Two unusual osteogenic orbital tumors: presumed parosteal osteosarcomas of the orbit.

OBJECTIVE: To report two cases of suspected parosteal osteosarcoma of the orbit, with dedifferentiation into a high-grade liposarcoma occurring in one patient. DESIGN: Two retrospective case reports. METHODS: The clinical, radiologic, and pathologic records of two patients with suspected orbital parosteal osteosarcoma were retrospectively reviewed. MAIN OUTCOME MEASURES: Histologic evaluation and clinical follow-up were measured. RESULTS: The first patient was a 47-year-old male presenting with a 5-month history of painless right lower lid swelling; excision biopsy suggested a well-differentiated parosteal osteosarcoma of the orbital floor, which recurred 3 years later. Six months after excision of the recurrence, the mass demonstrated accelerated growth, and a lid-sparing exenteration was performed; histologic examination showed a high-grade liposarcoma. The patient remains disease-free at 4 years. The second patient, a 40-year-old male, presented with an 8-year history of proptosis and a right superotemporal orbital mass. The mass was excised completely at lateral orbitotomy; histologic examination suggested a well-differentiated parosteal osteosarcoma. The patient remains well 9 months postoperatively. CONCLUSIONS: Parosteal osteosarcoma is an uncommon tumor, usually affecting long bones, that is extremely rare in the orbit. It is a low-grade sarcoma that tends to recur locally after excision but has a favorable prognosis. Dedifferentiation into a high-grade sarcoma occasionally occurs in parosteal osteosarcoma, but transformation into liposarcoma does not seem to have been previously reported. It is important to recognize dedifferentiated parosteal osteosarcoma, because the prognosis is poor, and radical treatment may be required.

Adult↗

PubMed2001

Bacterially mediated precipitation in marine stromatolites.

Stromatolites are laminated, lithified (CaCO3) sedimentary deposits formed by precipitation and/or sediment accretion by cyanobacterial-bacterial mat communities. Stromatolites have been associated with these communities as far back as the Precambrian era some 2+ billion years ago. The means by which microbial communities mediate the precipitation processes have remained unclear, and are the subject of considerable debate and speculation. Two alternative explanations for microbially mediated precipitation include: (i) cyanobacterial photosynthesis increases pH in a system supersaturated in respect of CaCO3, resulting in CaCO3 precipitation and then laminated lithification, and (ii) decomposition of cyanobacterial extracellular organic matter (e.g. sheaths, mucilage and organic acids) by microheterotrophs leads to release of organic-bound Ca2+ ions and CaCO3 precipitation. We evaluated these explanations by examining metabolically active, lithifying stromatolitic mat communities from Highborne Cay, Bahamas, using microautoradiography. Microautoradiographic detection of 14CO2 fixation and 3H organic matter (D-glucose and an amino acid mixture) utilization by photosynthetically active cyanobacteria and microheterotrophs, combined with community-level uptake experiments, indicate that bacteria, rather than cyanobacteria are the dominant sites of CaCO3 deposition. In the oligotrophic waters in which stromatolites exist, microheterotrophs are reliant on the photosynthetic community as a main source of organic matter. Therefore, autotrophic production indirectly controls microbially mediated precipitation and stromatolite formation in these shallow marine environments.

Bacteria↗

PubMed2000

The role of microbes in accretion, lamination and early lithification of modern marine stromatolites.

For three billion years, before the Cambrian diversification of life, laminated carbonate build-ups called stromatolites were widespread in shallow marine seas. These ancient structures are generally thought to be microbial in origin and potentially preserve evidence of the Earth's earliest biosphere. Despite their evolutionary significance, little is known about stromatolite formation, especially the relative roles of microbial and environmental factors in stromatolite accretion. Here we show that growth of modern marine stromatolites represents a dynamic balance between sedimentation and intermittent lithification of cyanobacterial mats. Periods of rapid sediment accretion, during which stromatolite surfaces are dominated by pioneer communities of gliding filamentous cyanobacteria, alternate with hiatal intervals. These discontinuities in sedimentation are characterized by development of surface films of exopolymer and subsequent heterotrophic bacterial decomposition, forming thin crusts of microcrystalline carbonate. During prolonged hiatal periods, climax communities develop, which include endolithic coccoid cyanobacteria. These coccoids modify the sediment, forming thicker lithified laminae. Preservation of lithified layers at depth creates millimetre-scale lamination. This simple model of modern marine stromatolite growth may be applicable to ancient stromatolites.

Bahamas↗

PubMed2000

Oesophageal rhabdomyoma.

Extracardiac rhabdomyomas are rare benign tumours showing striated muscle differentiation. Seventy percent of these lesions occur in the head and neck region. The most common sites for these lesions are the larynx, pharynx, and the floor of the mouth. There has been only one previous report of a rhabdomyoma of the oesophagus; two further cases are described.

Adult↗

PubMed1995

Solitary benign peripheral-nerve tumours. Review of 32 years' experience.

Solitary benign peripheral-nerve tumours are rare and may be difficult to diagnose correctly. Surgical excision may increase the patient's symptoms and may not be necessary. We have reviewed the presentation, clinical findings and histology of 104 solitary tumours presenting at one centre between 1959 and 1990. Male patients predominated for both schwannoma and neurofibroma. There was considerable but variable delay before presentation; 94% of patients complained primarily of a mass and less than half had pain or paraesthesia. The correct diagnosis had been made in only a few cases before operation, and the incidence of neurological symptoms doubled after exploration. We emphasise the need for vigilance, accurate preoperative diagnosis, and careful surgery.

Adolescent↗

PubMed1994

Aneuploidy in atypical fibroxanthoma: DNA content quantification of 10 cases by image analysis.

It has recently been reported that atypical fibroxanthoma (AFX) is a predominantly diploid lesion in contrast to malignant fibrous hystiocytoma (MFH) which is usually aneuploid. To test this hypothesis, DNA content quantification was undertaken on Feulgen-stained cytology and tissue section preparations from 10 cases of AFX by image analysis. The large atypical cells which characterize AFX were aneuploid in each case. Smaller spindle-shaped cells found in this lesion were diploid. The results suggest that AFX is indistinguishable from MFH by DNA content estimation and highlight an advantage of image analysis over flow cytometry.

Aneuploidy↗

PubMed1994

Image analysis derived ploidy and proliferation indices in soft tissue sarcomas: comparison with clinical outcome.

AIMS: To compare prognostic information obtained by image analysis cytometry of paraffin wax embedded soft tissue sarcomas with conventional assessment. METHODS: A CAS 200 image analyser was used to determine DNA content of Feulgen stained cytology preparations and tissue sections and to quantify immunostaining by Ki67 and PC10 antibodies. A mitotic count in 50 high power fields was undertaken and histological grade assigned by the Trojani system. Clinical details including follow up and outcome were obtained by case note review. The Kruskal-Wallis one way analysis test, Spearman rho significance test, Kaplan-Meier method, and log-rank test were applied in statistical analysis. RESULTS: Ploidy status, DNA index, 2.5c exceeding rate, 5c exceeding rate, mitotic count and Trojani grade all correlated significantly with clinical outcome. The relation between Ki67 index and outcome did not reach significance. The PC10 index and outcome were not related. Only 2.5c exceeding rate, 5c exceeding rate, and mitotic count correlated significantly with Trojani grade. CONCLUSIONS: DNA content determination of soft tissue sarcomas by image analysis provides quantifiable information of benefit in prediction of outcome. Larger series are required to determine the independent value of ploidy. In this study quantification of anti-Ki67 and anti-PC10 immunostaining was not of prognostic benefit) by contrast with mitotic count and Trojani grade.

Cell Division↗

PubMed1987

Late postpartum eclampsia.

A case of new-onset seizures occurring 12 days postpartum is described. The patient presented with headache, hypertension, and proteinuria. Postpartum eclampsia was diagnosed and IV magnesium sulfate was administered. The patient had no further seizures and did not require long-term anticonvulsants. Medical and neurologic evaluations failed to reveal any other etiology for the seizures.

Adult↗