The effect of bleach duration and age on the ERG photostress test

Background: The ERG photostress test assesses the recovery of the focal 41 Hz ERG following exposure to a bright light that bleaches a significant proportion of photopigment. The aims of this study were: 1) to compare the repeatability of the ERG photostress test recovery time constant following long and short duration light exposure, and 2) to determine the effect of age on the ERG photostress test recovery time constant. Methods: Focal 41 Hz ERGs were recorded from 23 participants (age range 20–71 years) at 20-second intervals for 5 minutes following either a short-duration (photoflash) or long-duration (equilibrium) light exposure. After a 5-minute wash-out period, the procedure was repeated using the second bleach modality. The time constant of cone recovery was determined by fitting an exponential model to the amplitude recovery data. The whole procedure was repeated on a second occasion. The co-efficient of repeatability (CoR) was calculated for each bleaching technique. The relationship between the time constant of recovery and age was investigated (Pearson’s correlation coefficient). Results: The time constant of recovery following an equilibrium bleach was more repeatable than recovery following a photoflash (CoR = 85s and 184s respectively). Eight trials (from seven participants) failed to show a reduction in amplitude following the photoflash, suggesting that a blink or fixation loss had occurred. All participants were reliably light-adapted by the equilibrium bleach. For the equilibrium bleach data, the time constant of recovery increased with age at a rate of 27 seconds per decade. Conclusions: The equilibrium bleach was more reliable and repeatable than the photoflash. Increasing participant age was shown to result in a lengthening of the recovery time constant, of a magnitude comparable to previously published psychophysical data

Screening for diabetic retinopathy: the optometrist’s perspective

Yousef H Aldebasi, Priya R Reddy, Vishakh G Nair, Mohammad Ijaz Ahmed Department of Optometry, College of Applied Medical Sciences, Qassim University, Buraidah, Kingdom of Saudi Arabia Abstract: Diabetic retinopathy (DR) is a micro-vascular complication of diabetes affecting nearly all persons with a duration of diabetes of ≥15 years; and is the most common cause of blindness in the working-age adult population in developed countries. Vision loss results mainly from macular edema, macular capillary nonperfusion, vitreous hemorrhage, and tractional retinal detachment. Timely and appropriate care at early stages of DR can significantly reduce visual loss over time, improve patients’ quality of life, and reduce the financial burden associated with the complications of visual impairment. Treatment modalities such as retinal photocoagulation, intraocular injections of pharmacological agents, and vitreo-retinal surgery have been effective in the management of DR. Optometry is a health care profession that is concerned with eyes and related structures, vision, and the visual system. Apart from refraction and visual rehabilitation, optometrists have a wide range of roles to play in DR management by performing new visual acuity tests, detecting DR early using dilated ophthalmoscopy and if required imaging modalities, monitoring disease progression, providing timely follow-up examinations and management which are critical for early diagnosis and intervention, making referral for concurrent care when indicated, and, above all, educating the patient. The optometrist's participation in the shared care of DR management regimen is likely to result in improvement in patient outcomes. This review is aimed at highlighting what primary-care optometrists are doing to manage this sight-threatening disease, what they can and should do to improve their competence in providing eye care to patients with diabetes, and what guidelines they need to follow to improve visual outcomes in the management of DR and diabetes mellitus. Keywords: diabetes mellitus, diabetic retinopathy, disease detection, disease monitoring, management and referral, patient educatio

Noble silver nanoparticles (AgNPs) synthesis and characterization of fig Ficus carica (fig) leaf extract and its antimicrobial effect against clinical isolates from corneal ulcer

Nanotechnology is rapidly growing with nanoparticles produced and utilized in a wide range of pharmaceutical and commercial products throughout the world. In this study, fig (Ficus carica) leaf extracts were used for ecofriendly extracellular synthesis of stable silver nanoparticles (AgNPs) by treating an aqueous silver nitrate (1 mM) solution and using the plant F. carica leaf extracts as reducing agents. The bioreduced silver nanoparticles were characterized by ultra violet visible (UV-Vis) spectrophotometer, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). The average particle size ranged from 5 to 40 nm. The particle size could be controlled by changing the reaction temperature, leaf broth concentration and AgNO3 concentration. Further, these biologically synthesized nanoparticles concentration of 50 µl were found to be highly effective and exhibited maximum microbial activity with mean zone of inhibition 20.33±1.00 mm and 18.00±1.00 against pseudomonas aeruginosa and Aspergillus fumigatus isolated from human corneal ulcer patients. This environmentally friendly green synthesis is an eco-friendly approach to conventional chemical synthesis and can potentially be used in various areas such as food, cosmetics, and medical applications and hope the recent technology can provide next generation of anti-microbials.Keywords: Ficus carica, silver nanoparticles, characterization, antimicrobial activity.African Journal of Biotechnology, Vol 13(45) 4275-428

Combination of glycosphingosomes and liposomal doxorubicin shows increased activity against dimethyl-α-benzanthracene-induced fibrosarcoma in mice

Masood A Khan,1 Ahmed N Aljarbou,2 Yousef H Aldebasi,1 Mohammed S Alorainy,3 Arif Khan1 1College of Applied Medical Sciences, 2College of Pharmacy, 3College of Medicine, Qassim University, Buraydah, Saudi Arabia Abstract: The present study aimed to assess the antitumor effect of glycosphingolipid-incorporated liposomes (glycosphingosomes) in combination with liposomal doxorubicin (Lip-Dox) in a mouse model of fibrosarcoma. Glycosphingosomes were prepared by incorporating glycosphingolipids isolated from Sphingomonas paucimobilis into the liposomes of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, cholesterol, and cardiolipin. Tumors were induced by administering dimethyl-α-benzanthracene, and tumor-bearing mice were treated with various formulations of Dox, including free Dox, Lip-Dox, or glycosphingosomes + Lip-Dox. Mice were observed for 90 days to monitor their survival and tumor size. Free Dox, but not Lip-Dox or a combination of glycosphingosomes and Lip-Dox, caused the substantial depletion of leukocytes and significantly increased the levels of lactate dehydrogenase and creatinine kinase in mice. Tumor-bearing mice treated with a combination of glycosphingosomes and Lip-Dox showed restricted tumor growth and increased survival when compared to those treated with free Dox or Lip-Dox. The results of the present study suggest that a combination of glycosphingosomes and Lip-Dox may prove to be very effective in the treatment of tumors. Keywords: glycosphingolipids, NKT cells, tumors, chemotherap

MfERG responses to long-duration white stimuli in glaucoma patients

The intent of our study was to evaluate whether the response to a long-duration white stimulus in the multifocal electroretinogram (mfERG) is sufficiently sensitive to detect early retinal dysfunction in glaucoma. On-off mfERGs were recorded from 15 NTG and 15 HTG patients and compared with 14 control subjects. Recording parameters were the following: LED stimulus screen (RETIscan?), 100-ms stimulus duration, 200-ms stimulus interval, 11-min total recording time, stimulus matrix of 61 elements, frame rate: 70 Hz, Lmax: 180 cd/m(2), Lmin: 0 cd/m(2), and filter setting: 1-200 Hz. The second negative response following stimulus onset (N2-on), as well as following stimulus offset (N2-off), was analyzed as an overall response and in quadrants, as well as in 4 small central and four adjoining peripheral areas per quadrant. The latency of the N2-on was significantly delayed in HTG in all response averages tested, while in NTG this was only seen in the overall response and in the small central response averages (P > 0.05). The most sensitive measure in HTG was the latency of the N2-on of the small peripheral response average of the superior temporal quadrant with an area under the ROC curve of 0.881. For NTG, the most representative measure was the latency of the N2-on of the small central response average of the inferior nasal quadrant with an area under the ROC curve of 0.793. Our results showed that in stimulation with long-duration flashes, the second negative response following the on response, representative of the early PhNR, is affected in glaucoma where N2-on showed a latency delay in POAG patients. The latency delay of the N2-on was more prominent for HTG than for NTG