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Biomedical subjects

P Beaumont

Publications and source records attributed to P Beaumont.

At least 19 recordsLinked to original sources
PubMed2001

Border Cave revisited: a revised ESR chronology.

In view of a decade of progress in ESR dating we have revised the ESR chronology of Border Cave. A detailed gamma ray survey in 1994 and newly calculated beta attenuation data led to total dose rate estimations that are between 0 and 30% smaller than previously estimated. Accordingly, the resulting ESR age estimates are between 0 and 30% older. The ESR dates are now in good agreement with independent age estimates, particularly(14)C and amino acid racemization. New ESR dates for the lowermost dated sedimentary layer, 5 WA (white ash), indicate that the sedimentation of the sequence started around 200 ka ago.

Animals↗
PubMed1997

Widespread choroidal insufficiency in primary open-angle glaucoma.

PURPOSE: The purpose of this study was to investigate choroidal perfusion in glaucoma, using histological and angiographic techniques. METHODS: We examined the choroidal vasculature in clinicopathological slides from 25 cases of primary open-angle glaucoma, five cases of optic atrophy, and 18 normal eyes. We measured choroidal thickness at fixed distances from the disk margin with light microscopy. Using a quantitative computer image analysis system, we established the depth of all vessels and the best fitting diameter and width-to-length ratio for each vessel in three pairs of eyes. Separate statistical analyses were done on the parapapillary area and the whole choroid. We compared standard fluorescein angiographic measures to peak choroidal filling time in a further 78 glaucoma and 84 normal eyes. RESULTS: Choroids were significantly (approximately 50 microns) thinner in glaucoma than in normal or optic atrophy irrespective of fundal position. Vessel frequency and mean diameter, relative to normal, showed greatest decrease near the choriocapillaris. Peak choroidal filling was the only fluorescein angiographic measure that was significantly delayed in glaucoma irrespective of age. CONCLUSIONS: Reduced choroidal thickness in primary open-angle glaucoma is primarily due to loss of the innermost choroidal vessels. Overall size decreases without significant flattening. These changes are not seen with optic atrophy alone and may be correlated with the delayed choroidal perfusion seen in fluorescein angiography.

Aged↗
PubMed1996

Activated protein C resistance--low incidence in glaucomatous optic disc haemorrhage and central retinal vein occlusion.

PURPOSE: Activated protein C (APC) resistance has recently been reported as conferring a sevenfold increase in the risk of venous thrombosis. It is linked to a genetic mutation in the factor V gene which occurs commonly (about 2% to 4% of the community have the mutation). Glaucoma patients with nerve fibre layer (NFL) haemorrhages on the optic disc and patients with central retinal vein occlusion (CRVO) were tested for APC resistance to determine if there was an association. METHODS: Twenty-three patients with glaucomatous NFL haemorrhages and 23 patients with CRVO were tested. The CRVO cases included 11 with relatively young age of onset (mean 45.1 +/- 6.9 years) without conventional vascular risk factors. Eighty randomly selected Red Cross blood donor samples and 33 staff members were tested as controls. Clotting times with and without exogenous APC were recorded and an APC ratio determined. Cases with APC resistance were tested to confirm that they had the factor V Leiden gene. RESULTS: No cases of APC resistance were identified in the glaucoma patients and only one of the younger CRVO patients tested positive, but four of 113 controls tested positive. The difference in prevalence between groups is not significant. The mean APC ratios for the three groups were very similar: NFL haemorrhages 5.46(+/- 1.62), CRVO 5.70(+/- 1.56), controls 5.34 ( +/- 1.19) p > 0.5. CONCLUSION: There was not clear association detected between glaucomatous NFL haemorrhages or CRVO and APC resistance in this sample of patients. This negative finding is important due its known association with venous thrombosis elsewhere in the body.

Adult↗
PubMed1995

[Functional study of Swanson's metacarpophalangeal arthroplasties in rheumatoid arthritis].

To validate a functional hand evaluation and to obtain an historical control group in a project of metacarpophalangeal total joint prosthesis, we reviewed our experience over a ten year period of Swanson's metacarpophalangeal joint arthroplasty in rheumatoid arthritis. Forty-nine implants in fourteen rheumatoid arthritis patients were reviewed clinically, radiologically and evaluated by the Arthritic Hand Function Test. The mean follow up was 4.5 years. All patients were ready to repeat the experience except one. The mean metacarpophalangeal joint range of motion was 37 degrees (18 degrees to 55 degrees) with a mean of 7 degrees ulnar deviation. Although their functional performance was 50% of normal, all patients completed the test. The strength was generally greater on the operated side. The low complication rate (6% fracture rate) with the successful functional outcome of Swanson's metacarpophalangeal joint arthroplasty in rheumatoid arthritis will be the gold standard for any new implant to develop.

Adult↗
PubMed1994

Isolated bulbar conjunctival Kaposi's sarcoma.

We present a case of an isolated bulbar conjunctival Kaposi's sarcoma in a man with HIV infection. This is an unusual site for the initial presentation of Kaposi's sarcoma and in this site can be confused with a caroticocavernous fistula, cavernous haemangioma or chronic subconjunctival haemorrhage. Biopsy is required to confirm the diagnosis in isolated disease. Local radiotherapy is the preferred treatment for isolated Kaposi's sarcoma.

Adult↗
PubMed1994

[Efficacy and safety of prophylactic preoperative administration of low-dose warfarin in cemented total knee prostheses].

One hundred and fifty six consecutive cemented total knee arthroplasties (TKA) in 147 patients (39 males, 108 females, mean age: 67) received preoperatively low-dose-warfarin for thromboembolic prophylaxis. Warfarin 10 mg was given the night before surgery and warfarin 5 mg the night of surgery. Thereafter, the dosage was adjusted to maintain a prothrombin time between 1.2-1.5 times control (INR = 2.0-3.0). The screening for any deep vein thrombosis (DVT) in the operated limb was by ascending venography. The reported incidence of DVT after TKA without prophylaxis is superior to 50%, more than 10% of those are proximal DVT. In this study, the overall incidence of DVT is down to 22.4%. Only five patients (3.4%) had a proximal DVT. There were no deaths and no clinical pulmonary embolisms. Patients with venous insufficiency had a significantly higher incidence of DVT (36.7%, p = 0.05). The average blood loss was 406 ml. Three major local bleedings occurred (2.0%). At one year follow-up, there were no infections. Low dose warfarin is efficacious in reducing DVT formation with TKA. It is safe and does not create excessive bleeding in cemented TKA.

Adult↗
PubMed1991

Differentiation of cytomegalovirus infection from acute rejection using renal allograft fine needle aspirates.

Cytomegalovirus (CMV) infection is an important cause of renal allograft dysfunction and may be difficult to distinguish from acute transplant rejection both clinically and histologically. To establish the early diagnosis of CMV infection, we used immunohistochemical staining with antibodies against CMV early nuclear protein (CMV-A) and histocompatibility leukocyte class II antigen (DR) in renal transplant fine needle aspirates. Fifty-eight aspirates from 27 patients were assessed, 53 for CMV-A and 53 for DR. Positive staining was defined as greater than or equal to 35% stained tubular cells for CMV-A and greater than or equal to 30% stained tubular cells for DR. Clinical diagnoses were made retrospectively without using the information obtained from aspirate diagnoses. CMV-A staining was negative in 44 aspirates, none at the time of CMV infection. CMV-A was positive in nine aspirates, seven during CMV infection (78%, P less than 0.00001 versus CMV-A negative). DR staining was never present in the absence of acute rejection. All aspirates performed during acute rejection had positive DR staining (P less than 0.00001 versus DR negative). Aspirates with acute rejection comprised 80% of all DR-positive aspirates, whereas those with CMV infection included only 13%. The percent CMV-A staining increased with CMV disease progression; DR staining decreased after successful treatment of acute rejection. These data demonstrate that CMV-A staining is associated with CMV infection whereas DR staining is not. DR staining is specifically related to acute rejection. CMV-A and DR staining of fine needle aspirates is a potentially valuable diagnostic tool to distinguish rapidly between CMV infection and acute transplant rejection as the etiology of renal allograft dysfunction.

Antigens, Viral↗
PubMed1986

Canthaxanthine (orobronze) retinopathy.

A 50-year-old white Australian male was found on routine examination to have small golden particles in the macular region of both eyes. A history of canthaxanthine (Orobronze) ingestion to produce skin bronzing was obtained.

Canthaxanthin↗