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Biomedical subjects

D B Archer

Publications and source records attributed to D B Archer.

At least 163 records · Page 9Linked to original sources
PubMed1985

Localised gamma irradiation and experimental intraocular proliferation.

A controlled study was undertaken to assess the effect of gamma irradiation on post-traumatic intraocular cellular proliferation. A standard perforating injury in the posterior segment of the rabbit eye was used to induce intraocular cellular proliferation and vitreo-retinal membrane formation. The site of injury was irradiated with an ophthalmic Cobalt60 applicator which provided a continuous source of gamma rays. Non-irradiated eyes developed traction retinal detachments associated with post-traumatic vitreo-retinal membranes. Irradiated eyes developed attenuated membranes or atrophic retinal scars, with the retina remaining attached. The membranes in non-irradiated eyes were highly cellular with abundant collagen, while irradiated membranes had fewer cells within a sparse collagen matrix. The episcleral fibroblasts, on autoradiographic studies appeared to be the main source of the cells that formed the proliferating tissue in both non-irradiated and irradiated eyes. In irradiated eyes both the inflammatory response and division of fibroblasts were delayed and reduced.

Animals↗
PubMed1985

The effect of plasma glucose control by continuous subcutaneous insulin infusion or conventional therapy on retinal morphology and urinary albumin excretion.

The effect of plasma glucose control on retinal morphology, urinary albumin excretion and related haematological and lipid measurements was studied prospectively for 30 weeks in 17 patients with insulin-dependent diabetes mellitus. All had background diabetic retinopathy (BDR) and absence of albustix positive proteinuria: 9 were allocated to a continuous subcutaneous insulin infusion (CSII) group and 8 to a conventional therapy (CT) group. There was a sustained reduction (p less than 0.01) in haemoglobin A1 (HbA1) in the CSII group, but not in the CT group. Mean HbA1 over the 30 week study period was lower (p less than 0.05) in the CSII (8.9 +/- 0.3%) than the CT group (10.2 +/- 0.5%). Retinal morphology assessed by fluorescein angiography improved after 30 weeks in one patient in the CSII group, but in most patients it remained the same or deteriorated. The patient with the best plasma glucose control developed a small area of neovascularisation. Less deterioration in retinopathy was not related to better plasma glucose control. Urinary albumin excretion, plasma viscosity, plasma fibrinogen, red cell deformability and plasma lipids did not change in either the CSII or CT group. In the 7 patients selected from both groups who achieved the best control there was a reduction in urinary albumin and LDL cholesterol.

Adolescent↗
PubMed1984

An ultrastructural study of retinal photoreceptor degeneration associated with bronchial carcinoma.

We studied both eyes of a 66-year-old man with retinal degeneration and oat cell carcinoma of the bronchus. Retinal degeneration was most marked peripheral to the parafovea where photoreceptor cells and their outer segments were absent. Within the parafovea, photoreceptor cells remained but rod outer segments were absent and cone outer segments were fragmented and disorganized. The retinal pigment epithelium contained many immature melanin granules within melanolysosomes, suggesting abnormal melanin synthesis and resorption. We suggest that a pharmacologically active substance resembling a hormone produced by the tumor increased melanin synthesis in the pigment epithelium and that the increased melanin content in these cells compromised their ability to phagocytose and maintain normal turnover of photoreceptor outer segments. We believe these changes led to photoreceptor outer segment loss and subsequent degeneration of the photoreceptor cells.

Aged↗
PubMed1984

Hydrogen-using bacteria in a methanogenic acetate enrichment culture.

In a study of the anaerobic utilization of acetate, an enrichment culture of sewage sludge organisms was initiated with calcium acetate as the sole carbon and energy source. A mixed bacterial population became established from which 14 anaerobic species were isolated. Two of the isolates were methanogenic bacteria but only one of these, Methanosarcina barkeri, utilised acetate as an energy source in axenic culture. The other methanogenic isolate, a Methanobacterium sp., utilised H2/CO2 but not acetate. A third methanogen, which was morphologically identical to Methanothrix soehngenii, was detected in the enrichment but was not obtained in monoculture. 2-Bromoethanesulphonate, a specific inhibitor of methanogenesis, completely inhibited the enrichment at a concentration of 10 mumol/l. Addition of H2 formate or methanol to the enrichment did not affect the rate of methanogenesis. An H2-utilizing Desulfovibrio sp. was also isolated from the enrichment.

Acetates↗
PubMed1984

Diabetic retinopathy in pregnancy.

The records of 23 insulin-dependent diabetics who had serial ophthalmological examinations during pregnancy and afterwards were reviewed. Fourteen pregnancies occurred in 10 patients with no retinopathy; 30% of these patients had obstetric complications. The mean birthweight was 3.5 kg. Ophthalmological status was unchanged in this group. In eight patients with background retinopathy during 10 pregnancies the obstetric complication rate was 70% and mean birthweight 3.3 kg. During pregnancy there was no evidence of progression of retinopathy. One patient developed proliferative retinopathy 4 years later. Five patients had proliferative retinopathy. The mean age (32 years) and duration of diabetes at index pregnancy (18 years) was greater than for the other groups. All patients developed pre-eclampsia and mean birthweight was 2.8 kg. Four of these patients required argon laser photocoagulation in association with pregnancy for progressive retinopathy; one died subsequently from end-stage diabetic nephropathy; the other four have maintained their pre-pregnancy visual acuity from 4 to 10 years.

Adult↗
PubMed1984

Detection and quantitation of methanogens by enzyme-linked immunosorbent assay.

Antisera to two methanogenic bacteria, Methanosarcina barkeri and a Methanobacterium sp., were raised in rabbits and used to develop an enzyme-linked immunosorbent assay (ELISA) method. ELISA was shown to be a sensitive technique, detecting as little as 4 ng of methanogen protein. The specificities of the antisera toward other methanogens were evaluated, and it was found that the antisera recognized species of the same genus as the immunizing species, but gave very little cross-reaction with methanogens of different genera. ELISA was used to estimate the growth of methanogens in pure culture. In natural environments and in anaerobic digesters methanogens exist as part of a mixed bacterial community, so the possibility of using ELISA to quantitate methanogens in mixed cultures was examined. The two antisera gave very little reaction in ELISA when non-methanogenic bacteria were used as antigens and ELISA was used to quantitate methanogens in an acetate enrichment culture. I conclude that the ELISA is a useful method for quantitating methanogens in defined mixed cultures, but has limited applicability to more complex systems.

Journal Article↗
PubMed1984

Effect of fluorometholone (FML) on the intraocular pressure of corticosteroid responders.

Steroid responsiveness to dexamethasone was determined in a large family with an established dominant form of chronic simple glaucoma. The high and intermediate steroid responders were then tested with fluorometholone--a steroid which is claimed to have a reduced risk of increasing intraocular pressure. It was found that fluorometholone had a much less pronounced ocular hypertensive effect than dexamethasone. However, one patient showed a comparable response on both drugs, and this suggests that some caution must still be exercised when using the drug on susceptible individuals. Fluorometholone was also found to be more irritable to the eye than dexamethasone.

Dexamethasone↗
PubMed1983

Contusional eye injuries: retinal and choroidal lesions.

The fundi of 114 patients were evaluated one to 14 years following contusional eye injury. Most injuries to children occurred at sport and play. Domestic and civil assaults, sporting injuries and industrial accidents were common. Males in the second and third decades of life were predominantly affected. Iris tears, pupillary abnormalities and angle recession were typically associated with the fundal lesions. Contusional injuries of the retina and choroid were found in 92 patients and were graded according to their location, extent and severity. Twenty-six patients (grade 1) had focal or diffuse disturbances of the inner or outer retina. In 15 patients the lesions predominantly affected the receptor-retinal pigment epithelial layers and in six patients there were associated breaks in Bruch's membrane. Five further patients had atrophic inner retinal alterations and lamellar holes at the macula. Most patients in this group retained good visual function. Thirty-six patients (grade 2) had single or multiple choroidal tears. In 21 instances the outer retina was primarily involved; however, in 15 cases there was associated inner retinal damage. Only three patients developed subretinal neovascularisation. Sixteen patients (grade 3) had extensive areas of chorioretinal atrophy associated with retinal pigment epithelial atrophy, proliferation, plaque and membrane formation. Fourteen patients (grade 4) developed retinal holes or tears and 10 proceeded to retinal detachment two weeks to 14 years following injury. Contusional retinal and choroidal lesions have an unfavourable visual prognosis, only 38.6% of patients regaining a visual acuity of 6/12 or better.

Adolescent↗
PubMed1982

An ultrastructural study of carcinoid tumor of the iris.

An iris tumor developed in a 37-year-old woman who had had a bronchial carcinoid tumor resected nine years previously. The iris tumor was locally excised with a modified trabeculectomy approach. Histologic studies showed it to be a metastatic carcinoid tumor. Electron microscopy demonstrated typical dark and pale carcinoid cells with neurosecretory granules, basal bodies, and apical microvilli. The cisternae of the granular endoplasmic reticulum were disposed in a series of concentric rings encapsulating a central core of mitochondria. This unusual type of subcellular organization and specialization is probably a reflection of the slow-growing and highly differentiated nature of the iris tumor.

Adult↗
PubMed1982

I.m. or i.v. atropine or glycopyrrolate for the prevention of oculocardiac reflex in children undergoing squint surgery.

The frequency and nature of the oculocardiac reflex and its prevention by atropine or glycopyrrolate (i.m. and i.v.) has been studied in 160 children undergoing surgery for the correction of squint. Ninety per cent of those given no anticholinergic premedication exhibited the reflex. This was decreased to about 50% in those receiving the drugs i.m. Glycopyrrolate 7.5 micrograms kg-1 and atropine 15 micrograms kg-1 i.v. were effective in most instances, the latter being slightly better. However, glycopyrrolate was associated with tachycardia of smaller magnitude. The reflex was observed more often following traction on the medial rectus muscle.

Adolescent↗
PubMed1982

Analysis of HLA antigen association with proliferative diabetic retinopathy.

One hundred and thirteen patients with insulin dependent diabetes mellitus for at least 15 years were typed for 22 HLA antigens of the A and B series. Fifty-six patients had severe bilateral proliferative retinopathy and 57 had no retinopathy. There was no statistical difference in frequency of HLA antigens between the 2 groups of diabetic patients. There was a significantly higher frequency of HLA B15 and a significant lower frequency of HLA B14, B17 in the combined diabetic groups than in a control population of 200 normal blood donors.

Diabetes Mellitus, Type 1↗
PubMed1982

Anterior segment consequences of blunt ocular injury.

The anterior segments of 212 eyes (205 patients) were evaluated one to 14 years after contusional eye injuries. Anterior chamber angle recession was the commonest complication, occurring in 153 of 190 eyes examined (80.5%). However, only one patient developed ocular hypertension. Iris abnormalities were found in 37.3% of eye injured, the most common abnormalities being marginal tears and pupillary defects. Cataract or lens dislocation attributable to trauma occurred in 24.5% of eyes, but most lens opacities were localised, stationary, and not associated with significant loss of vision. 15.4% of eyes developing lens opacities had cataract extraction within 18 months of the injury. Functional corneal sequelae were rare, but occasionally corneal opacities masked perforating injuries.

Adolescent↗