Age-related changes on physicochemical properties of the artificial vitreous humor: A practical tool for enhancing ex vivo studies

The vitreous humor (VH) is a hydrophilic, jelly-like ocular fluid, which is located in the posterior chamber of the eye. The rheological, structural, and chemical properties of VH change significantly during aging, which further causes eye-associated diseases and could be a potential indicator for various diseases. In this study, artificial VH (A-VH) samples were created by taking into account different age groups to observe age-related changes in the physicochemical properties of these samples. This study aimed to measure the physicochemical properties of age-dependently prepared A-VH samples to determine the changes with aging in the physicochemical properties of A-VH samples. Phosphate-buffered saline (PBS)-based A-VH samples were prepared in three types representing adult, middle-aged, and elder individuals. Age-related changes in physicochemical properties (surface tension, osmolality, pH, relative viscosity, density, and refractive index) were analyzed by related equipment. The A-VH samples, prepared using PBS, showed strong similarity to authentic VH in terms of physicochemical properties. While the age-related changes studies have revealed some discrepancies between age-dependently prepared A-VH samples in terms of surface tension, osmolality, relative viscosity, and pH with high correlation coefficients (r2 > 0,94), density and refractive index values did not show any significant differences and correlation between types of A-VH representing 3 age groups. In conclusion, age-dependent A-VH samples were created successfully to use ex vivo method development studies, and the influence of aging on the physicochemical properties of VH was demonstrated as well.

Temperature dependence of the current-voltage characteristics of Sn/PANI/p-Si/Al heterojunctions

Sn/PANI/p-Si/Al heterojunctions were fabricated by electropolymerization of aniline on chemically cleaned p-Si substrates. Current-voltage characteristics of Sn/PANI/p-Si/Al heterojunctions measured in the temperature range 140-280 K are presented and analyzed. Although these devices were clearly rectifying, their I-V characteristics were non-ideal, which can be judged from the nonlinearity in the semi-logarithmic plots. The high values of the ideality factor n depending on the sample temperature may be ascribed to a decrease of the exponentially increasing rate in current due to space-charge injection into the PANI thin film at higher forward bias voltages. Careful analysis of the forward bias I-V characteristics on a log-log scale indicates that the space-charge-limited current (SCLC) conduction controlled by an exponential trap distribution above the valence band edge dominates the current transport in the PANI/p-Si diodes at high voltages. Furthermore, the PANI was characterized by using Fourier transform infrared (FTIR) and ultraviolet-visible (UV-vis) spectra.

Three-layer reconstruction with fascia lata and vascularized pericranium for anterior skull base defects

BACKGROUND

We report an assessment of the efficiacy of a triple layer graft composed of fascia lata and vascularized pericranium for anterior skull base reconstruction. This technique is based on the concept that vascularized tissue over a free flap may promote vascularization and rapid wound healing.

METHOD

A large fascial graft is prepared from the fascia lata and divided in two pieces and trimmed to a size larger than the bone and dural defect. Vascularized pericranium is harvested after bicoronal incision and elevating the bifrontal scalp flap down to the supraorbital rims. First is dural repair, which is performed with fascia lata placed between the brain and remaining dura. Second, fascia lata is placed over the skull base defect and secured with mini titanium screws over the cranial surface of the orbital ridges. Third, vascularized pericranium is laid between the two layers of fascia lata.

FINDINGS

We studied 17 patients of whom 2 had malignancy, 6 had olfactory groove meningioma, 6 had skull base fracture and rhinorrhea, 1 case had orbital meningioma, 1 had invasive pituitary adenoma and 1 had basal encephalocele. The transbasal approach was used as a single procedure in 13 cases. The extended transbasal approach combined with a transfacial approach was used in 3 cases and with a pterional approach in 1 case. In each patient, reconstruction of the cranial base was performed with triple layer graft of fascia lata and vascularized pericranium. The patients were followed-up 2 months to 5 years. None of the patients experienced postoperative cerebrospinal fluid leakage, meningitis, abscess, brain herniation and tension pneumocephalus.

INTERPRETATION

Fascia lata with vascularized pericranium is highly reliable, tensile and well suited for reconstruction of the anterior skull base.

Efficacy of methylprednisolone in acute experimental cauda equina injury

In this experimental study the efficacy of methylprednisolone was investigated by neurophysiological and histopathological evaluation in a rabbit cauda equina model where injury was produced with an aneurysm clip (closed pressure 192 gr). High dose methylprednisolone (kg/30 mg) was administered by intravenous infusion in the 8th, 16th and 24th hours after injury followed by infusion of the same dosage every 6 hours for 24 hours. Nerve conduction velocity was measured before and early after trauma and 3 weeks after injury. Both neurophysiological and histopathological investigations demonstrated the neuroprotective effectiveness of methylprednisolone if it was given in the 8th hour after trauma. Although recovery was observed its efficacy was less pronounced when it was given in the 16th and 24th hours.

Comparative tear concentrations of topically applied ciprofloxacin, ofloxacin, and norfloxacin in human eyes

The tear pharmacokinetic profiles of 0.3% ciprofloxacin, 0.3% ofloxacin, and 0.3% norfloxacin ophthalmic solutions after a single drop topically administrations in the eyes of 30 healthy volunteers were evaluated. Tear samples collected at 30, 120, 180, and 240 minutes, were analyzed for drug concentrations by high performance liquid chromatography (HPLC) with fluorometric detection. Topically applied ciprofloxacin, ofloxacin, and norfloxacin achieved the mean tear concentrations (mean +/- SD) of 11.28 +/- 6.98, 6.52 +/- 4.06, and 13.28 +/- 8.78 micrograms/g at 30 min, and then fell to 3.52 +/- 1.30, 4.82 +/- 1.80, and 5.79 +/- 4.80 micrograms/g at 240 min, respectively. Topical norfloxacin achieved mean tear level significantly higher than ofloxacin at 30 min (p = 0.031). There were no statistically significant differences in the mean tear levels of ciprofloxacin versus ofloxacin (at 30, 120, 180, and 240 min), ciprofloxacin versus norfloxacin (at 30, 120, 180, and 240 min) and ofloxacin versus norfloxacin (at 120, 180, and 240 min). However, the mean tear levels, 240 min after dosing ciprofloxacin and norfloxacin, fell to the statistically significant concentrations (p = 0.02 and p = 0.01, respectively). But, it is concluded that concentrations of ciprofloxacin, ofloxacin, and norfloxacin in tears were still significantly greater than the minimum inhibitory concentrations for the most sensitive organisms, 240 min after a single drop application.

Congenital cholesteatoma with spontaneous epidural abscess, sinus thrombosis and cutaneous fistula

A congenital cholesteatoma or epidermoid is a benign mass that causes devastating effects if left untreated. An unusual case with a congenital cholesteatoma located in the mastoid region complicated by epidural abscess, sinus thrombosis, and cutaneous fistula is presented. The patient had normal otologic findings and had no neurologic deficit. A review of the literature found no report of a similar case.

Experimental evaluation of peritoneum and pericardium as dural substitutes

Although many substances have been tested in the search for an ideal dural substitute, an entirely satisfactory material has still not been found. The authors report an experimental study involving the closure of dural defects in rabbits with biomaterials developed from pig peritoneum and pericardium. Macroscopic and histologic examination, performed over a period between 15 and 45 days after implantation showed slight or no adhesion between the graft material and the cortex. No infection, CSF leakage, fistula or toxicity was noticed. The results demonstrated that these biomaterials could be used as satisfactory dural substitutes.

Unusual malformations in occult spinal dysraphism

Two cases of occult spinal dysraphism with different clinical symptoms, signs and congenital pathologies are presented. One had malformations including scoliosis, dermoid tumor, hydromyelia, diastematomyelia, dermal sinus, low conus, vertebrae anomalies and dextrocardia. The occurrence of dextrocardia in association with occult spinal dysraphism was found to be extremely unusual. The second case is presented in relation to the rarity of teratoma with dermal sinus and tethered cord in the lumbar area. Myelography, computed tomography, (CT), Myelo CT and magnetic resonance were used in making a diagnosis.

An experimental evaluation of response to contrast media: Pantopaque, iopamidol, and iohexol in the subarachnoid space

Myelography in dogs was performed with Pantopaque, iopamidol and iohexol. The effects of these agents were evaluated by histologic study of the brain, spinal cord, and meninges four months after the procedure. Retained Pantopaque was always accompanied by some degree of arachnoidal reaction, mild in the cervical cord segment and severe in the most caudal part of the cul-de-sac. No apparent protection against Pantopaque arachnoiditis was provided by either intrathecal or intramuscular methylprednisolone. We found no histologic evidence of arachnoiditis in animals examined with iopamidol and iohexol.