There have been multiple conflicting reports about the biocompatibility and antimicrobial activity of graphene oxide. To address this, we conducted a study to characterize the antimicrobial properties of graphene oxide (GO) and its biocompatibility with mammalian cells. When GO was added to a bacterial culture at 25 μg/mL, the results showed that bacteria grew faster and to a higher optical density than cultures without GO. Scanning electron microscopy indicated that bacteria formed dense biofilms in the presence of GO. This was shown by a large mass of aggregated cells and extracellular polymeric material. Bacterial growth on filters coated with 25 and 75 μg of GO grew 2 and 3 times better than on filters without GO. Closer analysis showed that bacteria were able to attach and proliferate preferentially in areas containing the highest GO levels. Graphene oxide films failed to produce growth inhibition zones around them, indicating a lack of antibacterial properties. Also, bacteria were able to grow on GO films to 9.5 × 10(9) cells from an initial inoculation of 1.0 × 10(6), indicating that it also lacks bacteriostatic activity. Thus, silver-coated GO films were able to produce clearing zones and cell death. Also, graphene oxide was shown to greatly enhance the attachment and proliferation of mammalian cells. This study conclusively demonstrates that graphene oxide does not have intrinsic antibacterial, bacteriostatic, and cytotoxic properties in both bacteria and mammalian cells. Furthermore, graphene oxide acts as a general enhancer of cellular growth by increasing cell attachment and proliferation.

SUMMARYThis paper reviews the changes which occur in the human lens in diabetes. They include refractive changes and cat aract and age-related increases in thickness, curvatures, light scattering, autofluorescence and yellowing. The inci dence of cataract is greatly increased over the age of 50 years, slightly more so in women, compared with non diabetics. Experimental models of sugar cataract provide some evidence for the mechanism of the uncommon, but morphologically distinct, juvenile form of human dia betic cataract, where an osmotic mechanism due to sugar alcohol accumulation has been thoroughly studied in dia betic or galactose-fed rats. The discrepancy between the ready accumulation of sugar alcohol in the lens in model systems and the very slow kinetics of aldose reductase (AR) has not been satisfactorily explained and suggests that the mechanism of polyol formation is not yet fully understood in mammalian systems. The activity of AR in the human lens lies mainly in the epithelium and there appears to be a marginal expectation that sufficient sorbi tol accumulates in cortical lens fibres to explain the lens swelling and cataract on an osmotic basis. This is even more so in the cataracts of adult diabetics, which re semble those of age-related non-diabetic cataracts in appearance. The very low levels of sorbitol in adult dia betic lenses make an osmotic mechanism for the increased risk of cataract even less likely. Other mech anisms, including glycation and oxidative stress, are dis cussed. The occurrence of cataract is a predictor for increased mortality in the diabetic.The diabetic lens is larger than normal, disposed to refrac tive change and at increased risk of cataract, sometimes of a specific type. This paper discusses the factors involved. ANATOMY AND PHYSIOLOGYThe lens is enclosed in a collagenous capsule containing other matrix proteins and proteoglycans. A monolayer of epithelial cells is interposed between the anterior capsule and the main cellular mass of lens fibres. The lens fibres are laid down in a series of onion-skin layers, which arch over the equator to meet their opposite numbers at the lens sutures. The innermost fibres comprising the nucleus of the lens are free of organelles and show limited metabolic activity. The outer fibres comprise the cortex. The most superficial fibres of the cortex are nucleated and, like the epithelium, show the normal complement of organelles. Glucose, which enters the lens by facilitated transport, I is its main energy supply, although energy may also derive from amino acids? The metabolism of the cortex is chiefly anaerobic, with 70% of the energy supply of the lens deriving from anaerobic glycolysis. If a lens is incubated in nutrient medium in anaerobic conditions with an adequate supply of glucose it remains transparent for a number of hours.3.4 The metabolism of the epithelium is aerobic. New lens fibres arise by cell division in the germi native zone in the pre-equatorial region of the lens. The epithelium and superficial cortical cells are major ...

An attempt has been made to clarify the two most important issues relevant to personal eye dosimetry. This involves the identification of the cells which are most at risk from radiation and the specification of their position in the eye. A survey of the radiobiological literature concerning animals and humans shows that the epithelial cells in the equatorial region of the lens are those which are involved in radiation cataract induction. The depth of these cells has been evaluated in the human eye by means of geometrical construction. The relevant dimensions have been determined from a survey of published anatomical data and supplemented by new data obtained by slit-image photography. In a normal adult population (20-65 years) the minimum depth of the incriminated cells is 2.3 plus or minus 0.4 mm; the upper and lower values are associated with young and old subjects respectively. Approximate calculations for isotropic 90Sr/90Y and 106Rh beta-radiation fields indicate that a planar dosemeter, which integrates the tissue dose between depths of 2.5-3.5 mm, should give a reasonable measure of the mean equatorial dose for the variety of eye and irradiation geometries likely to be met during a life-time exposure. The long established, but tentative, value of 3 mm for the effective depth of the lens is thus confirmed.

Vitrectomy and tamponade produced a characteristic transient PSC in the immediate postoperative period. Disruption of fluid balance in the region of the posterior lens was suggested by the morphological appearance. The acute changes resolved but were followed by accelerated nuclear opacification.

The review has year limits and further research needs to identify support for both the patients and family caregivers.

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A composite slit-lamp based system for the clinical classification and grading of cataract is described. Cataract features are classified morphologically, and individual features are graded by comparison with standard diagrams mounted adjacent to the slit-lamp. Attention has been paid to relevant aspects of measurement theory, with equal interval steps between the grades. The image degrading effect of the cataract is assessed using a 'resolution target projection ophthalmoscope'. The method may be used in conjunction with photographic and image analysing techniques.

In previous studies of superficial comeal disorders (Bron and Brown, 197I) and of superficial lines of the cornea (Brown and Bron, I976), we were impressed by the frequency of recurrent erosion of the cornea. In this study we have set out to examine patients presenting with recurrent erosion of the cornea to establish the type and incidence of the superficial corneal disorders, and to compare this incidence with that in a control group of subjects. Some experience of management of these patients is also reported. (Fig. i). In macroform recurrent erosion, a large area of epithelium was separated from the cornea (Fig. 2). TREATMENT AND FOLLOW-UPThe initial treatment was decided by the Casualty Officer and consisted of either chloramphenicol drops or chloramphenicol ointment with hyoscine 0 5 per cent drops, and padding for the eye. Patients with large bags of loose epithelium were treated initially by debridement, the loose corneal epithelium being carefully removed at the slit lamp with a Bard Parker no. I5 blade, using centripetal strokes to avoid stripping off an unnecessarily large area of epithelium. The eye was then treated with drops or ointment and padded as above.Eyes which failed to heal on medical treatment and produced redundant loose epithelium were debrided as above. In those eyes which still failed to heal on this regime, the debridement was repeated and followed by carbolization with IOO per cent phenol applied at the slit lamp with a small stick to the dried cornea. Care was taken to avoid carbolizing the pupillary area of the cornea, but the phenol was otherwise applied to as much of the affected area as possible.Once healing was complete the patients were given sodium chloride 5 per cent ointment to apply each evening immediately before going to bed. This treatment was continued for from 3 to i8 months.