An Ultrasonically Powered Implantable Microprobe for Electrolytic Ablation

Electrolytic ablation (EA) is a promising nonthermal tumor ablation technique that destroys malignant cells through induction of a locoregional pH change. EA is typically performed by inserting needle electrodes inside the tumor followed by application of direct current (DC), thus inducing electrolysis and creating localized pH changes around the electrodes. In this paper, we report an ultrasonically powered implantable EA microprobe that may increase the clinical relevance of EA by allowing wireless control over device operation (capability to remotely turn the device on and off) and providing flexibility in treatment options (easier to administer fractionated doses over a longer period). The wireless EA microprobe consists of a millimeter-sized piezoelectric ultrasonic receiver, a rectifier circuit, and a pair of platinum electrodes (overall size is 9 × 3 × 2 mm³). Once implanted through a minimally invasive procedure, the microprobe can stay within a solid tumor and be repeatedly used as needed. Ultrasonic power allows for efficient power delivery to mm-scale devices implanted deep within soft tissues of the body. The microprobe is capable of producing a direct current of 90 µA at a voltage of 5 V across the electrodes under low-intensity ultrasound (~200 mW/cm²). The DC power creates acidic (pH < 2) and alkaline (pH > 12.9) regions around the anode and the cathode, respectively. The pH change, measured using tissue-mimicking agarose gel, extends to 0.8 cm³ in volume within an hour at an expansion rate of 0.5 mm³/min. The microprobe-mediated EA ablative capability is demonstrated in vitro in cancer cells and ex vivo in mouse liver.

Epiretinal Membrane: Prevalence and Risk Factors from the Korea National Health and Nutrition Examination Survey, 2008 through 2012

PURPOSE

To investigate the prevalence and risk factors for an epiretinal membrane (ERM) in Korean population.

METHODS

Using the database of the Korea National Health and Nutrition Examination Survey from 2008 through 2012, 14,772 participants 40 years of age or older with gradable fundus photographs were included. The presence of ERM was determined by using fundus photographs. The prevalence of ERM was estimated and possible risk factors including systemic factors, nutritional status, and blood tests were analyzed via multiple logistic regression analyses.

RESULTS

The prevalence of ERM was 2.9% (95% confidence interval [CI], 2.6% to 3.3%). On multiple logistic regression analysis, the prevalence of ERM was affected by age. The odds ratios (ORs) against the forties were 2.70, 5.48, and 5.69 in the fifties, sixties, and seventies, respectively. ERM was also significantly affected by cataract surgery (OR, 2.82; 95% CI, 2.08 to 3.81) and by the increase in intake of 100-mg calcium (OR, 1.05; 95% CI, 1.00 to 1.11). ERM had negative associations with red blood cell count (OR, 0.66; 95% CI, 0.45 to 0.95).

CONCLUSIONS

The estimated nation-wide prevalence of ERM in Korea is 2.9%. The presence of ERM in the general population is associated with age, cataract surgery, increased dietary calcium, and a low red blood cell count.

Triamcinolone acetonide protects the rat retina from STZ-induced acute inflammation and early vascular leakage

Streptozotocin (STZ) has been commonly used to induce in vivo and in vitro hyperglycemic diabetes and its toxicity leads to inflammation and vascular injury. Triamcinolone acetonide (TA), as an anti-angiogenic/anti-inflammatory drug, is clinically used to improve the visual acuity in neovascular and edematous ocular diseases. The aim of this study was to investigate the effect of TA on early inflammation and vascular leakage in the retina of STZ-induced hyperglycemic rats. Hyperglycemia was induced in 8-week-old male Sprague-Dawley (SD) rats by a single intraperitoneal injection of STZ (65 mg/kg); only rats with blood glucose levels >13.9 mmol/l 1 day after STZ injection were included in STZ-hyperglycemic group. Sex- and age-matched SD rats injected with buffer were used as the control group. One day before STZ and buffer injection, 2 microl TA (4 mg/ml in saline) and 2 microl saline were intravitreal-injected into the right and the left eyes of rats, respectively. Retinal vascular leakage was measured using the Evans-blue method. Changes in pro-inflammatory target genes, such as tumor necrotic factor (TNF)-alpha, intracellular adhesion molecule (ICAM)-1, and vascular endothelial growth factor (VEGF) were assessed by immunoblottings, immunostaining, and ELISA analyses. Vascular hyperleakage and up-regulation of most pro-inflammatory genes peaked within a few days after STZ injection and had recovered. However, these changes were blocked by TA pretreatment. Our data suggest that TA controls STZ-induced early vascular leakage and temporary pro-inflammatory signals in the rat retina.

Triamcinolone suppresses retinal vascular pathology via a potent interruption of proinflammatory signal-regulated activation of VEGF during a relative hypoxia

We examined the effect of triamcinolone acetonide (TA), a corticosteroid, on the relationship between vascular pathophysiology and vascular endothelial growth factor (VEGF) activation in the retina of a rat model of oxygen-induced retinopathy (OIR). OIR was induced by exposure of hyperoxia (80% oxygen) to Sprague-Dawley (SD) rats from P2 to P14 and then returned to normoxic conditions. TA was intravitreal-injected once into the right eye of OIR rats at P15. Effects of TA on vascular pathophysiology or changes of various genes in response to hypoxia and/or proinflammation under hypoxic retina were assessed by the Evans-blue method, fluorescein isothiocyanate-dextran (FITC-D) infusion, immunoblotting, and ELIZA. TA not only reduced retinal neovascularization and vascular leakage in the OIR-rat retina, but also blocked the induction of hypoxia-response proinflammatory genes before it negatively controlled VEGF activation. These findings suggest a potential that TA suppresses retinal neovascular pathophysiology via proinflammation-mediated activation of VEGF during hypoxia.

Ethanol decreases the expression of mitochondrial cytochrome c oxidase mRNA in the rat

To evaluate the molecular and cellular bases of effects of ethanol on the brain, we utilized a differential display-polymerase chain reaction. Several cDNA fragments were differentially expressed in the hippocampus of control vs. ethanol-treated rats. One of these genes was homologous to the rat mitochondrial cytochrome c oxidase mRNA. Northern blot analysis revealed that the expression of this message in the whole hippocampus was clearly lower after ethanol treatment. Using in situ hybridization, we also found that cytochrome c oxidase mRNA expression, especially in the CA1 and CA3 of the hippocampal regions, was significantly decreased by ethanol treatment. As cytochrome c oxidase is related to oxidative stress, the present study suggests that ethanol might affect the brain through modulation of an oxidative stress reaction.

Contact dermatitis in Korean dental technicians

The high risk of occupational contact dermatitis in dental personnel are well accepted throughout the world. There are few reports concerning occupational skin disease in dental personnel in Korea. The purposes of this study were to investigate the frequency, characteristics and causative factors of contact dermatitis in Korean dental technicians. Recording of personal history, physical examination and patch tests with the Korean standard series and dental screening series were performed in 49 dental technicians. Most of the subjects were exposed to a variety of compounds, including acrylics, metals, plaster, alginate, etc. 22 (44.9%) subjects had contact dermatitis, present or past, and the site involved was the hand in all 22. The most common clinical feature of hand dermatitis was itching (77.3%); scaling, fissuring and erythema were other common clinical features. Metals, including potassium dichromate (24.5%), nickel sulfate (18.4%), mercury ammonium chloride (16.3%), cobalt chloride (12.2%) and palladium chloride (10.2%), showed high positive rates in patch test results of 49 dental technicians. 7 positive reactions to the various acrylics were found in 3 subjects. In our study, the frequency and clinical features of the contact dermatitis showed a similarity to other reports, though the patch test results were somewhat different; a higher patch-positive reaction to metals and a relatively lower patch-positive reaction to acrylics than the patch test results reported in Europe.