[Corneal neovascularization: review article]

Corneal neovascularization occurs through inordinate wound healing after infection, injury or surgery. Neovascularization is formation of new vascular structures in the locations which had not already vessels. The two overlapping mechanisms including vasculogenesis and angiogenesis are probably involved in neovascularization process, and the last mechanism is more involved in tumor growth and corneal and retinal disorders. In fact, corneal neovascularization is a visual threatening status that usually occurs along with inflammatory or infectious disorders of the eye surface. The studies of angiogenesis-related cancer showed that there is a balance between angiogenic factors [such as VEGF and FGF] and antiangiogenic molecules [such as angiostatin, endostatin and pigment epithelium-derived factor; EPDF] in cornea. Problems such as inflammation, infection, injury and lesions result in corneal neovascularization, which are due to stimulation of angiogenesis in this tissue. Corneal neovascularization may be influenced by matrix inetalloproteinase [MMPs] and other proteolytic enzymes. The application of new medical and surgical therapies such as angiostatic steroids, non-steroidal anti inflammatory drugs, argon laser photocoagulation and photodynamic therapy [PDT] in animal models had been efficient to some extent for inhibition of corneal neovascularization. In this study we reviewed neovascularization-dependent corneal disorders and molecular processes involved in this disorder, and also their potential therapies

Comparative study between Fibrin Scaffold and autograft in sciatic nerve repair: a tissue engineering approach

Autograft is the golden standard approach to repair the cut peripheral nerve. Howeverdue to limited accessibility to autograft and the high risk of neuroma formation, an alternative repair method is the target of many investigations. The objective of the present study was to investigate the effect of using fibrin scaffold [FS] in repairing cut sciatic nerve in rats. Forty five male Wistar rats weighing 200-250g were randomly divided into three groups, control, autograft [A] and the fibrin scaffold [FS]. The 5mm gap in cut right sciatic nerve was repaired with autograft and FS in A and FS groups. Animals were then assessed by behavioral and EMG tests in one, three and five weeks following the induced injury. Results were then compared in three groups using one way ANOVA. The trends of recovery were similar and comparable in both experimental groups when the data obtained in the first, 3rd and the 5th week were crossed with those gained from control group. The mean functional index of the sciatic nerve was in parallel in both experimental groups throughout the five weeks of follow-up period. The mean motor response delay had a similar trend and was not significantly different in experimental group. So was the amplitude of the mean motor action potential. The data presented are in favor of the notion that the fibrin scaffold could potentially be looked upon as an alteranative approach for autograft transplants in peripheral nerve injury

[Isolation and primary culture of rat thymic epithelial cells using actinidin enzyme of kiwi fruit]

Proteolytic enzymes specially collagenase are used for degredation of extracellular matrix, cell isolation and primary cell culture. It is important to substitute a low cost and easily obtained plant or animal protease for collagenase. In the present study the enzyme actinidin which is found abundantly in kiwi fruit, was used to isolate thymic epithelial cells from rat thymus. Actinidin with different concentrations [from 1 to 10 mg/ml] and at different times [3, 4 or 5h] was used to isolate rat thymic epithelial cells. The isolated epithelial cells were cultured on collagen coated dishes in Willam's E medium. The percentage of viable isolated cells was estimated by the trypan blue test and morphology of the cells examined microscopically after staining with Papanicoloau. Actinidin with a concentration of 4 mg/ml for 3.5-4 h digested extra-cellular matrix of rat thymus and isolated thymic epithelial cell appropriately. The rate of viability of the separated cells was estimated 90-95% in all isolates. The results of this study indicated actinidin is comparable to collagenase in isolation of epithelial cells from the thymus of rat and probably other animals. Considering its simpler purification and its low cost, this enzyme is a suitable and sale substitute for collagenase which can be used for isolation of thymic epithelial cells from rat and probably other animals

[Isolation of human umbilical vein endothelial cells and development of an angiogenesis model in fibrin matrix]

Angiogenesis plays a key role in different physiologic and pathologic processes. Evaluation of endothelial cells and finally new vessels development in-vivo is a complex and formidable task. Thus, we designed an in-vitro experimental angiogenesis model using human umbilical vein endothelial cells [HUVEC] which is highly reproducible and controllable. This model has applicability to study various parameters involved in angiogenesis and its harness. HUVEC cells were isolated from umbilical vein by enzyme treatment as the source of endothelial cells. Then, the three-dimensional model was designed using fibrin gel and cytodex beads which was covered by HUVEC cells. In this model 10-12 days after culturing HUVEC, the resulting capillary formation was observed as branching of the source endothelial cells in microscopic field. The model is controllable and highly reproducible to study various parameters involved in angiogenesis. Moreover, the model provides a reliable method to screen angiogenesis and anti-angiogenesis substances

Changes in the motor and sensory latencies of median nerve according to age

Even though there is a high prevalence of carpal tunnel syndrome patients, there are very few reliable papers on the study of normal values and changes in sensory and motor latency parameters of the median nerve in the wrist region on the basis of age of patients .This retrospective study was on the basis of 5 years data [1998-2003] from the electro diagnostic department of Sh. Sadoughi teaching hospital of Yazd. In this analytic and observational study, subjects included 1200 patients referring to the electrodiagnostic clinic and also randomly selected healthy patients. Exclusion criteria included systemic diseases such as diabetes, radiculopathy of cervical spine, peripheral neuropathy, positive Phallen test or Tinel sign and atrophy in the thenar region of the hand. Subjects were divided to ten groups on the basis of age. [10-80 years] Sensory and motor latency parameters of median nerve were studied in each age group. All data was evaluated using SPSS statistical software and ANOVA, LSDREST curve regression tests were used for analysis. All values less than 0.05 were considered significant. In this study, normal values for distal motor latency of median nerve were between 2.5-4.2ms with a +/- 2SD and mean value of 3.3ms. Increment in this value was mild [0.1ms per decade] after 5[th] decade of life. This value was calculated using the formula: Distal motor latency: [DML]8cm = 3.30+[AGE-50]/75 +/- 0.0025 age. Normal value for distal sensory latency of median nerve was 2.7-3.7ms with a +/- 2SD and mean value of 3.2ms. Increment in this value also was 0.1ms per decade after 5th decade of life. This value was calculated by the formula: Distal sensory latency: [DSL] 14cm=3.20+[AGE-50]/100 +/- 0.0025 age. It seems that age has a meaningful relationship with distal motor and sensory latencies in the wrist region and therefore in the future, electro diagnostic evaluation along with other increments in these parameters according to age should be considered when evaluating patients with carpal tunnel syndrome