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Biomedical subjects

A J Bron

Publications and source records attributed to A J Bron.

At least 127 records · Page 7Linked to original sources
PubMed1985

Medical therapy in the prevention of cataract.

Medical treatment of cataract depends on understanding the mechanism of cataract formation. This is established in sugar cataract, in which sugar is metabolised to sugar alcohol. Sugar alcohol accumulates and the resultant osmotic stress is considered to cause lens fibre damage. The conversion of sugar to alcohol is effected by the enzyme aldose reductase and interest now centres around the use of aldose reductase inhibitors. A controlled clinical trial into the effect of the spirohydantoin Sorbinil in adult diabetic cataract has started at Oxford. Aldose reductase inhibitors may also act on non-diabetic cataract, which is supported by some clinical evidence. The biochemical basis of this and other possible treatments for cataract are outlined.

Adult↗
PubMed1984

Ocular infection with orf virus.

Orf virus infection of the pericanthal eyelid skin and conjunctiva was diagnosed by electron microscopy. Orf is a paravaccinia virus responsible for contagious pustular dermatitis in sheep and goats. It occasionally affects humans. The patient was a farmwife who had recently handled lambs. She had a raised ulcerating lesion at the inner canthus, follicular conjunctivitis, and lymphadenopathy. Treatment with 35% idoxuridine in dimethylsulfoxide on the skin and 0.5% idoxuridine ointment on the conjunctiva led to resolution after three weeks.

Adult↗
PubMed1984

Contrast sensitivity and visual disability in chronic simple glaucoma.

A battery of vision tests was used to quantify visual defect in a group of 50 patients with chronic simple glaucoma. The vision tests were near and distance visual acuity, visual fields, and contrast sensitivity to static and temporally modulated sinusoidal grating patterns. Of these, static contrast sensitivity function appears to be the most sensitive method of measuring visual defect in glaucoma patients. The visual disability experienced by the glaucoma patients was quantified by means of a questionnaire, and the relationship between perceived visual disability and visual defect was examined. It was found that results from a group of tests, near visual acuity, visual field, and contrast sensitivity measures, are the best predictors of the difficulty experienced by patients in performing visually dependent daily activities.

Activities of Daily Living↗
PubMed1984

Laser treatment of primary ring-shaped epithelial iris cyst.

This is the first report of a ring-shaped, primary cyst of the iris pigment epithelium. The patient, a 28-year-old woman, presented with angle closure glaucoma. Ocular pressure was controlled medically, and the iris cyst was treated by argon laser photocoagulation. The derivation of the cyst, differential diagnosis, and mechanism of angle closure glaucoma are discussed.

Adult↗
PubMed1983

Prevention of deterioration of renal and sensory-nerve function by more intensive management of insulin-dependent diabetic patients. A two-year randomised prospective study.

74 insulin-dependent diabetic patients with background retinopathy were randomised to continue with usual diabetic care (group U) or to a more intensive programme (group A) using ultralente insulin as basal cover and soluble insulin at mealtimes. Group A attended the clinic more frequently, received closer dietary supervision, and were taught home blood glucose monitoring. Group A had a significantly lower mean glycosylated haemoglobin level during the study, although the mean level also fell in group U towards the end of year 2. Renal and sensory-nerve function were significantly better preserved in group A than in group U. Significant improvements were also seen in low-density-lipoprotein-cholesterol and whole-blood low-shear viscosity. The rate of progression of retinopathy was similar in both groups. It appears that a modest improvement in diabetic control, obtainable in most clinics, has been associated with a reduction in the progression of diabetic tissue damage.

Blood Glucose↗
PubMed1983

Plasma somatomedin activity and diabetic retinopathy.

Somatomedin activity was measured by a rabbit chondrocyte bioassay in plasma of adult patients with insulin-dependent diabetes of 11-28 years duration. Mean somatomedin activity in patients with background or proliferative retinopathy, assessed by ophthalmoscopy or fluorescein angiography, was 1.42 +/- 0.65 U/ml (n = 20) which was significantly greater than in age- and weight-matched control subjects (1.05 +/- 0.22 U/ml, n = 9). In contrast, somatomedin activity was not raised in patients who had no retinopathy (1.16 +/- 0.33 U/ml, n = 10). Diabetic patients with retinopathy also showed the greatest differences between repeat samples suggesting wider fluctuations in plasma somatomedin levels. Plasma growth hormone and glucose measured either simultaneously with somatomedin or during a 12-24 h profile were not different when diabetics with or without retinopathy were compared. The somatomedins have mitogenic actions in vivo on a variety of connective tissues. The possibility that this may extend to retinal vessels should be further evaluated.

Adult↗
PubMed1983

Plasma haemostatic factors and diabetic retinopathy.

Plasma coagulation factors were measured in twelve male insulin-dependent diabetics with no retinopathy, ten with background and ten with proliferative retinopathy and ten non-diabetics. Factor VIII pro-coagulant activities (VIII:C), ristocetin cofactor activities and factor VIII-related antigen concentrations (VIIIR:ag) were significantly related to the severity of diabetic retinopathy (P less than 0.025, trend test). The mean ratio of VIII:C/VIIIR:ag was lower in the diabetics with proliferative retinopathy than in the other groups of diabetics (P less than 0.05) or the controls (P less than 0.02). Concentrations of alpha 2 macroglobulin and alpha 1 antitrypsin were highest in diabetics with proliferative retinopathy (0.1 greater than P greater than 0.05, trend test) but mean prothrombin and activated partial thromboplastin times and mean concentrations of alpha 2 antiplasmin, plasminogen activator and antithrombin III were similar in all groups. Concentrations of the platelet-specific protein beta thromboglobulin, though higher in diabetics than controls (P less than 0.005), were not related to retinopathy. The plasma concentrations of coagulation factors did not correlate with creatinine clearance and there were no significant differences between groups in concentrations C-reactive protein; this suggests that the raised concentrations of coagulation factors in diabetics with retinopathy were not a result of associated nephropathy or an 'acute phase protein' response to diabetic tissue damage. Increased coagulation activity in diabetics may contribute to the development of retinopathy.

Adult↗
PubMed1983

NADPH-oxidising activity in lens and erythrocytes in diabetic and nondiabetic patients with cataract.

Levels of lens aldose reductase, aldehyde dehydrogenase activity, and erythrocyte NADPH-oxidising (or glyceraldehyde reductase) activity were determined in 17 diabetic and 16 nondiabetic patients undergoing cataract extraction. Lens aldose reductase and aldehyde dehydrogenase activities were significantly lower in diabetics than in nondiabetics. Both enzymes showed significant inverse correlations with grouped HbA1c and fasting blood glucose levels. By contrast, erythrocyte NADPH-oxidising activity showed a significant positive correlation with grouped HbA1C. It is suggested that a direct effect of the glycaemic status on the lens enzymes is masked by a loss of enzymes secondary to the development of cataract. It is not yet possible to say whether erythrocyte NADPH-oxidising activity can be used to monitor aldose reductase activity in the lens or other tissues in clinical trials of aldose reductase inhibitors.

Aged↗
PubMed1983

The relationship between diabetic control and retinopathy in a group of diabetic teenagers.

Twenty insulin-dependent diabetic teenagers from the Oxford pediatric diabetic clinic were recruited to study the relationship between diabetic control and retinal microvascular disease. Two patients (10%) had evidence of minimal background diabetic retinopathy on careful ophthalmoscopy. Retinal color photography and fluorescein angiography each revealed retinopathy in 5 patients (25%) and together revealed retinopathy in 7 patients (35%). Color photography demonstrated retinopathy which had not been discovered on ophthalmoscopy. The presence of retinopathy was related to the duration of diabetes (p less than 0.02) and the glycosylated hemoglobin level (p less than 0.01). It is concluded that multiple field color photography is a useful method of assessing patients with minimal or no ophthalmoscopic retinopathy.

Adolescent↗
PubMed1982

Low density lipoprotein cholesterol: an association with the severity of diabetic retinopathy.

Diurnal profiles of total and lipoprotein cholesterol and triglycerides were measured in 11 insulin-dependent diabetic subjects without retinopathy, 10 with background and 10 with proliferative retinopathy. The groups were closely matched for age and duration of diabetes. Total cholesterol levels were higher in patients with proliferative (5.6 +/- 0.5 mmol/l) than background (5.1 +/- 0.7 mmol/l) or no retinopathy (4.6 +/- 0.8 mmol/l, trend test; p less than 0.003), due to raised levels of low density lipoprotein (LDL) cholesterol (3.8 +/- 0.9, 3.2 +/- 0.6 and 2.8 +/- 0.8 mmol/l respectively; p less than 0.02). High density lipoprotein (HDL) levels were similar in patients with and without retinopathy and HDL/LDL ratios were lower with more severe retinopathy (p less than 0.025). Cholesterol levels were similar in diabetic subjects without retinopathy and in 12 normal subjects. Triglyceride levels were not related to retinopathy and no measure of plasma lipids correlated with HbA1 or 24-h mean plasma glucose. Total and LDL cholesterol were weakly inversely correlated with creatinine clearance but the association with retinopathy was independent of this effect.

Adult↗
PubMed1982

Blood viscosity, glycaemic control and retinopathy in insulin-dependent diabetes.

1. In a cross-sectional study, 32 insulin-treated diabetic patients had elevated low shear (27.1 vs 22.1 mPa s, P less than 0.05) and high shear blood compared with 10 non-diabetic controls. After correction to 45% packed cell volume, the abnormality had a tendency to be greater in patients with proliferative (mean low shear viscosity, 30.8 mPa s) than background (29.2 mPa s) or nil/minimal retinopathy (27.6 mPa s, 0.05 less than P less than 0.97, permutational trend test). 2. The fibrinogen levels were higher in the diabetic group (P less than 0.05) and correlated with the low shear blood viscosity (rs = 0.38, P less than 0.05). 3. In a prospective study, 74 insulin-treated diabetic patients with background retinopathy were randomized into two groups. Thirty-six patients were on attempted improved therapy (A group); in these the mean glycosylated haemoglobin (Hb A1c) fell within 1 year (11.6 to 10.1%, P less than 0.001). both the corrected low shear blood and plasma viscosity fell similarly (P less than 0.001). The fall was greater than in those patients who were kept on usual therapy (U group) and whose glycosylated haemoglobin did not change significantly (11.7 to 11.4% over the year. 4. The effect of diabetes on blood viscosity may not be a direct pathological factor, as the same increased viscosity would be produced by a mean increase of 1.7% in packed cell volume, compared with a population range of 14% packed cell volume.

Adult↗
PubMed1982

Limbal palisades of Vogt.

The palisades of Vogt are distinctive normal features of the human corneoscleral limbus. Our clinical studies indicate that they are more discrete in younger and in more heavily pigmented individuals, and that they appear more regular and prominent at the lower limbus than at the upper limbus. They are seen only infrequently in the horizontal meridian. There is some symmetry (though it is not exact) from one eye to the other in the same person. The anatomy of the palisades appears to be unique for a given individual. In this respect, as well as in their microscopic anatomy, the palisades of Vogt appear comparable to fingerprints, and the term "conjunctivoglyphics" ("conjunctival carvings") or "limboglyphics" is suggested in analogy with "dermatoglyphics." The palisades of Vogt have a distinct vasculature with narrow, barely visible, arterial and venous components of radially oriented hairpin loops. Angiography reveals that these vessels leak fluorescein relatively late and only to a moderate extent. They respond to inflammation by dilatation and gross breakdown of their physiologic barrier properties. The functions of the palisades of Vogt are not known with certainty, but their interpalisadal epithelial rete ridges may serve as a repository for corneal epithelial cells. They may thus be important in both aging and diseases of the cornea.

Adult↗
PubMed1981

The ocular and periocular features of multicentric reticulohistiocytosis with paraproteinaemia. A report of two cases.

Two patients with atypical multicentric reticulohistiocytosis are reported. Skin rigidity with mobile rubbery nodules, and telangiectases, are typical of this disease and occurred around the eyes and elsewhere. One patient also had subconjunctival nodules and corneal crystal formation probably due to her paraproteinaemia. Some literature on this disease and on the occurrence of corneal crystal deposition in dysproteinaemia is reviewed.

Aged↗
PubMed1981

Specular microscopy of the human lens.

Some specular features of the normal and abnormal human lens are described and recorded in vivo by macrophotography. Anteriorly the lens exhibits three distinct specular zones: a coarse shagreen, an epithelial pattern, and a lens fibre pattern. The posterior specular zone is relatively featureless. Uncorrected values for epithelial cell diameter in the central zone of the normal lens gave a mean of 13.9 microns. Lens fibre diameter in the same zone was 13.7 microns. The 'relief images' of the adult lens are also described, including perinuclear changes which have been termed retrodot lens opacities.

Adolescent↗
PubMed1981

Inherited recurrent corneal erosion.

The causes of inherited recurrent corneal erosion may be classified into two major groups: (1) Those associated with primary epithelial dystrophies, including the Franceschetti type, a newly described epithelial rosette dystrophy, basement membrane disorder, and Meesmann's dystrophy, (2) Those associated with the anterior limiting membrane, stromal, and endothelial dystrophies. There is also a third group, including epidermolysis bullosa, in which recurrent erosion attacks are part of a wider systemic disorder. Attention is drawn to the age at onset, presentation, morphological features, and progression of each disorder.

Adult↗