Effects of a new advanced glycation inhibitor, LR-90, on mitigating arterial stiffening and improving arterial elasticity and compliance in a diabetic rat model: aortic impedance analysis.

BACKGROUND AND PURPOSE: We determined the effects of treatment with LR-90, an inhibitor of advanced glycation end products, on the mechanical properties of the arterial system in streptozotocin (STZ)-induced diabetic Sprague Dawley rats, using aortic impedance analysis, and further investigated the effects of LR-90 on the progression of aortic pathology. EXPERIMENTAL APPROACH: STZ-induced diabetic rats were treated with or without LR-90 (50 mg L(-1) in drinking water) for 8 weeks and compared with control groups. Arterial BP measurements, various metabolic parameters, aortic histopathology, collagen cross-linking, AGE accumulation, and RAGE protein expression in aortic tissue were determined. Pulsatile parameters were evaluated using a standard Fourier series expansion technique and impulse response function of the filtered aortic input impedance spectra. KEY RESULTS: LR-90 reduced glycated haemoglobin and triglycerides levels, although it had no effect on the glycaemic status. LR-90 did not affect arterial BP, but prevented the diabetes-induced increase in peripheral resistance and variations in aortic distensibility, as it reduced aortic characteristic impedance by 21%. LR-90 also prevented the elevation in wave reflection factor, as indicated by a 22.5% reduction and an associated increase of 23.5% in wave transit time, suggesting it prevents the augmentation of the systolic load of the left ventricle. Moreover, LR-90 inhibited collagen cross-linking and the accumulation of AGE and RAGE in the vasculature of diabetic rats. CONCLUSIONS AND IMPLICATIONS: Treatment with LR-90 may impart significant protection against diabetes-induced aortic stiffening and cardiac hypertrophy and provides an additional therapeutic option for treatment of AGE associated diabetic complications.

Ketamine sedation during the treatment of retinopathy of prematurity.

AIMS: To report the use of ketamine sedation as an alternative anaesthetic method for babies undergoing treatment for retinopathy of prematurity (ROP). METHODS: All babies who underwent treatment for ROP over a 2-year period were included in this study. The babies preoperative weight, medical condition, and ventilation status was recorded. Data were collected on their ventilation status pre-, intra-, and postprocedure. Any change in their cardiac or respiratory status during or in the subsequent 3 days following the treatment was noted. RESULTS: Eleven babies, 22 eyes, required treatment over this period. The procedure was well tolerated with only three babies having intraoperative complications, which all resolved spontaneously. Two babies had postoperative complications requiring additional ventilation. In no case was the procedure abandoned owing to anaesthetic complications. CONCLUSIONS: The use of ketamine sedation allows the laser to be performed in a ward setting and avoids the potential risk of general anaesthesia and inter- and intra-hospital transfer. It has been found to produce few intra- or postoperative complications for the infant, while providing satisfactory conditions for the treatment of ROP.

Assisted conception and retinopathy of prematurity: 8-year follow-up study.

AIMS: To assess the effect of assisted conception (AC) on retinopathy of prematurity (ROP) and ROP screening. Follow-up to the study by McKibbin et al. METHODS: Retrospective study utilising computerised databases of ROP screening, live births, AC and multiple births between 1st April 2000 and 31st August 2003 at St James's Hospital (SJUH) Leeds. chi(2) tests of significance were used. RESULTS: ROP screening was undertaken in 11/265 (4.2%) of AC births versus 1.6% of all SJUH births. This is significantly less than the 20.3% of AC babies screened in McKibbin et al study (P=<0.01). There was no ROP detected in the 11 AC babies. Of all AC births, 36.9% were one of twins and 1.5% from triplet births compared to 46.0% one of twins and 18.6% one of triplets in McKibbin's study. CONCLUSIONS: The percentage of AC babies requiring ROP screening has fallen since McKibbin et al study which was performed between August 1991 and December 1994. This appears to be at least partially due to the reduced multiple birth rates. This reduction in the multiple birth rates follows evidence that reducing the number of embryos transferred does not reduce the number of couples taking home a baby and Human Fertility and Embryology Association guidelines recommending 'no more than two embryos should be transferred in an IVF cycle'. Changes in clinical practice at SJUH have significantly reduced the likelihood of AC babies requiring ROP screening and developing ROP.

The earliest case of retinopathy of prematurity?

Retinopathy of prematurity (ROP) is a well-recognized condition in premature babies born today and in the recent past. One would not normally expect to come across evidence of its existence among older patients. We present a case of apparent regressed ROP in a lady born in May 1939, prior to the documented reports of the first cases.

Retinopathy screening in children and adolescents with diabetes.

Diabetic retinopathy is a complication of diabetes that affects the blood vessels of the retina. The majority of patients with diabetic retinopathy exhibit background retinopathy. In approximately 10% of patients, background retinopathy will progress to sight-threatening retinopathy. The aims of our study were to measure the prevalence of retinopathy among our population and to assess the optimal time of screening children and adolescents with type 1 diabetes.

A model for the fluid motion of vitreous humour of the human eye during saccadic movement.

During saccadic motion the eyewall moves in a manner similar to a sinusoid or at least can be represented by a sine Fourier series. Motion of the vitreous is induced by the saccade and the vitreo-retinal interface is subjected to a time-dependent shear. This force may be a significant factor for retinal tearing in the neighbourhood of small retinal holes or tears. An analytical viscoelastic model and a numerical, Newtonian model of the motion of the vitreous are presented and compared. Under sinusoidal boundary motion the analytical model shows that a viscous wave propagates inward toward the axis of rotation and the characteristic length of this wave is a function of the Womersley number. The numerical solution indicates that the vitreous moves similarly to the analytical result with small secondary motion; however, this motion allows complete recirculation of the vitreous over large timescales. Excellent agreement is found between the analytical and numerical models. The time-dependent fluid shear is evaluated and from the analytical solution the maximum value of this is found to be proportional to R0 square root of v(omega)3, where R0 is the eye radius, v the modified complex viscosity and omega the sinusoidal frequency. This indicates that myopes have a larger shear force exerted on them by virtue of the larger eye size. Further work is directed toward a model which links the stress found in the sclera to that exerted on the vitreo-retinal interface by the vitreous fluid motion.

Malignant hypertension presenting as blurred vision in a 43 year old intravenous drug abuser.

A 43 year old intravenous drug abuser presented to the accident and emergency department with a three week history of bilateral visual loss and frontal headaches. Fundoscopy revealed bilateral retinal cotton wool spots and haemorrhages and an ophthalmic opinion was requested. His blood pressure was subsequently found to be 210/140. A diagnosis of malignant hypertension was made and blood pressure was gradually controlled on oral antihypertensives. This case illustrates the importance of checking the blood pressure of all patients presenting with visual loss.

Time-dependent stress and displacement of the eye wall tissue of the human eye.

Myopia or short sightedness, is the most important predisposing factor to retinal detachment. The relative risk of detachment rises with increasing myopia. The model characterizes that because the severity of myopia increases with the axial length (antero-posterior diameter) of the eyeball, the relative risk of retinal detachment rises with increasing eye size. We present a mathematical model of the time-dependent shear stress force that occurs in the thin eye wall shell supporting the vitreous humour inside the eye globe during the acceleration and deceleration phases of saccadic eye movement. Results show that the shear force increases as the thickness of the eye wall decreases. It is common for myopes to have thinner eye wall tissue than emmetropes. In addition, if account is taken of the increased force required to provide normal saccadic movement of myopic (larger) eyes, then the shear force is up to seven times greater than that experienced for emmetropes.

Incidence of lens matter dislocation during phacoemulsification.

PURPOSE: To assess the incidence and visual morbidity of lens matter dislocation during phacoemulsification and the relationship between this complication and surgical experience. SETTING: Teaching and district general hospitals. METHODS: A multiple-choice questionnaire was sent to members of the Northern and Midlands Ophthalmological Societies. They were asked about the incidence of lens matter dislocation, the visual outcome of the cases, and their surgical experience. RESULTS: Forty-seven of the 177 survey respondents (26.5%) were using phacoemulsification. The incidence of lens matter dislocation was 1.1%; 49.0% of the surgeons had experienced at least one case. The incidence increased significantly when surgeons assessed their expertise with phacoemulsification toward the expert end of the scale. Final visual acuity was worse than 6/12 in 35.0% of cases. CONCLUSIONS: The incidence of lens matter dislocation with phacoemulsification is significant and related to an incorrect assessment of expertise by the surgeons. The considerable visual morbidity associated with this complication can be minimized using the management strategy discussed.

Assisted conception and retinopathy of prematurity.

This study was performed to assess the workload imposed by treatment for infertility on a retinopathy of prematurity (ROP) screening programme. We reviewed the records of all babies born between August 1991 and December 1994 as a result of treatment in the Assisted Conception Unit of this hospital, and of all babies screened for ROP over the same period. Of the babies born after assisted conception treatment, 20% fulfilled the ROP screening criteria. ROP of any stage was present in 23% of all the assisted conception babies screened. This group also accounted for a large proportion of those reaching stage 3 disease and of those requiring treatment.