A novel mechanism of dasatinib-induced apoptosis in chronic myeloid leukemia; Ceramide synthase and ceramide clearance genes

Sphingolipids are bioeffector molecules that control various aspects of cell growth, proliferation, apoptosis, and drug resistance. Ceramides, the central molecule of sphingolipid metabolism, are inducer of apoptosis and inhibitors of proliferation. Sphingosine-1- phosphate (S1P) and glucosyleceramide, converted from ceramides by sphingosine kinase-1 (SK-1) and glucosyleceramide synthase (GCS) enzymes, respectively, inhibit apoptosis and develop resistance to chemotherapeutic drugs. In this study, we examined the therapeutic potentials of bioactive sphingolipids in chronic myeloid leukemia (CML) alone and in combination with dasatinib in addition to investigate the roles of ceramide-metabolizing genes in dasatinib-induced apoptosis. Cytotoxic effects of dasatinib, C8:ceramide, PDMP, and SK-1 inhibitor were determined by XTT cell proliferation assay. Changes in caspase-3 enzyme activity and mitochondrial membrane potential (MMP) were measured using caspase-3 colorimetric assay and JC-1 MMP detection kit. Expression levels of ceramide-metabolizing genes were examined by qRT-PCR. Application of ceramide analogs and inhibitors of ceramide clearance genes decreased cell proliferation and induced apoptosis. Targeting bioactive sphingolipids towards generation/accumulation of ceramides increased apoptotic effects of dasatinib, synergistically. It was shown for the first time that dasatinib induces apoptosis through downregulating expression levels of antiapoptotic SK-1 but not GCS, and upregulating expression levels of ceramide synthase (CerS) genes, especially CerS1, in K562 cells. On the other hand, dasatinib downregulates expression levels of both GCS and SK-1 and upregulate apoptotic CerS2, -5 and -6 genes in Meg-01 cells. Increasing endogenous ceramide levels and decreasing prosurvival lipids, S1P, and GC, can open the way of more effective treatment of CML.TÜBİTAK grant number 107S317; Turkish Academy of Science

Evaluation of possible factors affecting contrast sensitivity function in patients with primary Sjögren’s syndrome

ABSTRACT Purpose: The contrast sensitivity (CS) function in patients with primary Sjögren’s syndrome (pSS) may be impaired either frequently as a result of dry eye diseases or rarely as a result of optic neuropathy. In this study, we aimed to evaluate the CS function in pSS patients as well as to assess corneal aberrations and thickness of the peripapillary retinal nerve fiber layer (pRNFL). Methods: Fourteen eyes of 14 pSS patients (pSS group) and 14 eyes of 14 healthy participants (control group) were subjected to assessment of CS at the spatial frequencies of 1.5, 3.0, 6.0, 12, and 18 cycles/degree (cpd) using a functional visual acuity contrast test (FACT); measurement of corneal high-order aberrations (HOAs) in terms of coma-like, spherical-like, and total HOAs using Scheimpflug corneal topography; and measurement of the thickness of both the macular ganglion cell-inner plexiform layer (mGCIPL) and pRNFL in all quadrants using optical coherence tomography. None of the participants were under treatment with artificial tears. Results: The results of the CS test did not differ between the 2 groups at all spatial frequencies (p>0.05). In addition, there were no statistically significant differences between the 2 groups in terms of corneal HOAs (p>0.05) and thickness of mGCIPL (p>0.05). However, among all quadrants, only the inferior quadrant of pRNFL in pSS patients was statistically significantly thinner than that in the healthy participants (p=0.04). Conclusions: The CS function in pSS patients can be maintained with normal thickness of both pRNFL and mGCIPL and with lack of increased corneal HOAs, which may be present even in the absence of artificial tear usage

Quercetin protects the retina by reducing apoptosis due to ischemia-reperfusion injury in a rat model

Purpose: This study aimed to investigate the effect of quercetin on apoptotic cell death induced by ischemia-reperfusion (I/R) injury in the rat retina. Methods: Twenty-four rats were divided into four equal groups: control, ischemic, solvent, and quercetin. I/R injury was achieved by elevating the intraocular pressure above the perfusion pressure. Intraperitoneal injections of 20 mg/kg of quercetin and dimethyl sulfoxide (DMSO) were performed in the quercetin and solvent groups, respectively, immediately prior to I/R injury, and the researchers allowed for the retinas to be reperfused. Forty-eight hours after injury, the thicknesses of the retinal ganglion cell layer (RGCL), inner nuclear layer (INL), inner plexiform layer (IPL), outer plexiform layer (OPL), and outer nuclear layer (ONL) were measured in all groups. Moreover, the numbers of terminal deoxynucleotidyl transferase dUTP nick-end-labeled [TUNEL (+)] cells and caspase-3 (+) cells in both INL and ONL were evaluated in all groups. Results: The administration of quercetin was found to reduce the thinning of all retinal layers. The mean thickness of INL in the quercetin and ischemic groups was 21 ± 5.6 µm and 16 ± 6.4 µm, respectively (P<0.05). Similarly, the mean thickness of ONL in the quercetin and ischemic groups was 50 ± 12.8 µm and 40 ± 8.7 µm, respectively (P<0.05). The antiapoptotic effect of quercetin in terms of reducing the numbers of both TUNEL (+) cells and caspase-3 (+) cells was significant in INL. The mean number of TUNEL (+) cells in INL in the ischemic and quercetin groups was 476.8 ± 45.6/mm2 and 238.72 ± 251/mm2, respectively (P<0.005). The mean number of caspase-3 (+) cells in INL of ischemic and quercetin groups was 633.6 ± 38.7/mm2 and 342.4 ± 36.1/mm2, respectively (P<0.001). Conclusion: The use of quercetin may be beneficial in the treatment of retinal I/R injury because of its antiapoptotic effect on the retinal layers, particularly in INL

Fibrin sealant as a carrier for sustained delivery of antibiotics

Objective: To evaluate the activity and sustained release of antibiotics from fibrin sealant against common strains of ocular bacteria. Methods: Vancomycin, ceftazidime, moxifloxacin and lomefloxacin were incorporated into fibrin sealant in the shape of discs. Each antibiotic disc and control fibrin disc without drug was tested in vitro against standard bacterial strains of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae and Pseudomonas aeroginosa. After 24 hours of incubation at 37 °C, the discs were transferred to new plates of bacteria and triplicated for each antibiotic. Results: All antibiotic discs demonstrated detectable activity after 24 hours. Vancomycin had the longest duration of activity (4 days) on the S. pneumonia grown plate. The moxifloxacin discs showed a prolonged inhibition of S. aureus and S. pneumonia for 3 days and inhibited the other strains for 2 days. Conclusion: Fibrin sealants provided prolonged drug delivery, which indicates that antibiotic-loaded fibrin clots could be useful for early ocular postoperative care and treatment. J Clin Exp Invest 2014; 5 (2): 194-19

Protective Effect of Hesperetin and Naringenin against Apoptosis in Ischemia/Reperfusion-Induced Retinal Injury in Rats

Purpose. Hesperetin and naringenin are naturally common flavonoids reported to have antioxidative effects. This study was performed to investigate whether either hesperetin or naringenin has a protective effect against apoptosis on retinal ischemia/reperfusion (I/R) injury. Methods. Retinal I/R was induced by increasing the intraocular pressure to 150 mmHg for 60 minutes. Thirty-three male Wistar albino rats were randomised into 5 groups named control, I/R + sham, I/R + solvent (DMSO), I/R + hesperetin, and I/R + naringenin. Animals were given either hesperetin, naringenin, or the solvent intraperitoneally immediately following reperfusion. Thickness of retinal layers and retinal cell apoptosis were detected by histological analysis, tunel assay, and immunohistochemistry assay. Results. Hesperetin and naringenin attenuated the I/R-induced apoptosis of retinal cells in the inner and outer nuclear cells of the rat retina. Retinal layer thickness of the naringenin treatment group was significantly thicker than that of the hesperetin, sham, and solvent groups (P<0.05). Conclusions. Hesperetin and naringenin can prevent harmful effects induced by I/R injury in the rat retina by inhibiting apoptosis of retinal cells, which suggests that those flavanones have a therapeutic potential for the protection of ocular ischemic diseases

Evaluation of intraocular pressure and retinal nerve fiber layer thickness in patients with Helicobacter pylori

Objectives: High prevalence of Helicobacter pylori (HP) in the glaucoma patients was shown in recent studies. In our prospective study we aimed to compare the intraocular pressure (IOP) and the retinal nerve fiber layer thickness (RNFLT) in patients with HP positive and negative. Methods: In 91 patients with gastritis HP was investigated by urea breath test (UBT) and biopsy sample culture Following the full ophthalmologic examination the patients’ IOP was measured by Goldmann applanation tonometry and RNFLT was measured by spectral optic coherence tomography. The patients' demographic and clinical characteristics were compared with the χ² test for categorical variables and with the Mann Whitney U test for continuous variables. Results: Of the 90 patients who meet the including criteria, HP was detected in 74 patients (27 male, 47 female) positive, and in 16 patients (7 male, 9 female) negative. Median (minimum-maximum) age values were 46 (18-79) in HP positive group and 51 (18-67) in HP negative group. One hundred forty seven eyes in 74 HP positive patients and 31 eyes in 16 HP negative patients included in the study. Median IOP values were determined 14 (7-21) mmHg in HP positive group and 14 (8-18) mmHg in HP negative group. The measurements of RNFLT in superior, temporal, inferior and nasal quadrants found to be respectively 122(98-165), 68(50-101), 135(93-188), 79(51-120) micron in HP positive group and 120(94-161), 67(43-104), 129(94-166), 76(50-97) micron in HP negative group. No statistically significant difference was found when compared IOP and RNFLT measurements between the two groups (p<0.05). Conclusion: In this study found that the IOP and RNFLT measurements of HP positive group was not show statistically significant difference compared with HP negative group. In a large case series, randomized, case-controlled, histologic and serologic studies should be done to show the relationship between HP and glaucoma

Comparison of dynamic contour tonometry measurements with golmann applanation tonometry and tono-pen measurements

Bu çalışma; farklı kornea kalınlığı ve göz içi basıncı düzeylerine sahip olgularda Dinamik Kontür Tonometre ile yapılan ölçümleri, Goldmann Aplanasyon Tonometresi ve Tono-Pen ile yapılan ölçümler ile karşılaştırarak bu tonometrelerin ölçüm değerleri arasındaki farklılığı saptamak, kornea kalınlığının ve kurvatürünün ölçümler üzerine olan etkisini araştırmak amacıyla yapıldı. Çalışma koşullarına uyan 400 olgunun rutin oftalmik muayeneleri sonrasında, ultrasonik pakimetre ile santral kornea kalınlık ölçümleri yapıldı. Göz içi basınçları sırasıyla Goldmann aplanasyon tonometresi, dinamik kontür tonometresi ve Tono-Pen ile ölçüldü. Elde edilen verilen istatiksel değerlendirilmesinde Spearman korelasyon analizi, Blant-Altman analizi ve Wilcoxon testi kullanıldı. Göz içi basınç ölçümleri karşılaştırıldığında; dinamik kontür tonometresinin diğer tonometrelere göre anlamlı olarak yüksek ölçüm yaptığı saptandı (p=0,000). Göz içi basıncı yükseldikçe (r=0,284, p=0,000) ve kornea düzleştikçe (r= -0,155, p=0,002) dinamik kontür tonometresi ölçüm kalitesinin azaldığı bulundu. Kornea kalınlığının tonometrelerin ölçüm değerleri üzerine olan etkisi incelendiğinde; kornea kalınlığı ile dinamik kontür tonometresi arasında korelasyon olmadığı (r=0,007, p=0,888), ancak Goldmann aplanasyon tonometresi (r=0,189 p=0,000) ve Tono-Pen (r=0,183, p=0,000) ile arasında pozitif korelasyon olduğu saptandı. Olgular kornea kalınlığına göre üç grupta incelendiğinde; ince kornealı olguların sunuçlarının ana grup ile benzer olduğu, normal ve kalın kornealı olgularda ise tüm tonometreler ile kornea kalınlık arasında ilişki olmadığı görüldü. Yüksek göz içi basınç seviyelerinde dinamik kontür tonometresi ve Goldmann aplanasyon tonometresi arasında anlamlı fark olmadığı (p=0,150), diğer tüm göz içi basınç seviyelerinde dinamik kontür tonometresinin GİB'leri anlamlı olarak yüksek ölçtüğü tesbit edildi (p=0,000). Sonuç olarak, ince kornealı olgularda Goldmann aplanasyon tonometresi ve Tono-Pen hatalı düşük ölçümler yapmaktadır. Buna karşın dinamik kontür tonometresinin kornea kalınlığı ve kurvatüründen daha az etkilenerek göz içi basınç ölçümü yapması, onun daha üstün bir yöntem olduğunu göstermektedir. Anahtar kelimeler: Dinamik Kontür Tonometresi, Goldmann aplanasyon tonometresi, Tono-Pen, santral kornea kalınlığıThe purpose of this study was a comparison of dynamic contour tonometry with the Goldmann applanation tonometry and Tono-Pen with respect to mean of intraocular pressure at patients who have got different corneal thickness and corneal curvature and the influence of ocular structural factors on intraocular pressure.The central corneal thickness measurement with ultrasonic pachymeter has been performed, after periodic ophthalmic examination of 400 patients who agreed with inclusion criteria. The intraocular pressures are measured subsequently with Goldmann applanation tonometry, dynamic contour tonometry and Tono-Pen. Spearman correlation analysis, Blant -Altman analysis and Wilcoxon signed ranks test has been used for statistical analysis of data. In the comparison of intraocular pressure measurements; dynamic contour tonometry with Goldmann applanation tonometry results (r=0,875, p=0,000) and dynamic contour tonometry with Tono-Pen results (r=0,812, p=0,000) were found significantly correlated; and also dynamic contour tonometry measures statistically higher values than the others (p=0,000). It is determined that, when intraocular pressure gets higher and cornea gets smoother (r= -0,155, p=0,002), the quality of dynamic contour tonometry measurement is decreasing. In the evaluation of central corneal thickness effect on the tonometers; it is determined that there is no correlation between dynamic contour tonometry and central corneal thickness (r=0,007, p=0,888), besides there are positive corelation between central corneal thickness and Goldmann applanation tonometry (r=0,189 p=0,000) / Tono-Pen (r=0,183, p=0,000) measurements. In the the analysis of samples in three groups it is determined that; the results of samples with thin corneas are smillar with the whole group and there is no relation between tonometers and central corneal thickness in the normal and thick corneas. For higher intraocular pressure levels, it is determined that there is no reasonable difference between dynamic contour tonometry and Goldmann applanation tonometry (p=0,150) and for the other intraocular pressure levels dynamic contour tonometry measures higher than Goldmann applanation tonometry and Tono-Pen (p=0,000). Consequently, in the samples with thin corneas, Goldmann applanation tonometry and Tono-Pen measures faulty low values. Besides, as dynamic contour tonometry measures intraocular pressure with fewer influenced by corneal thickness and curvature, it showes to be a better method in diagnosis and follow up of glaucoma.Key words: Dynamic Contour Tonometry, Goldmann applanation tonometry, Tono-Pen, central corneal thicknes

Evaluation of Parameters Affecting Measurement Quality of Dynamic Contour Tonometry

Objective: To evaluate factors affecting measurement quality of dynamic contour tonometry (DCT).Material and Methods: Three hundred patients took part in this prospective clinical study. For each patient, measurements for one eye were included in the study. Of the participants, 116 had ocular hypertension, 114 had glaucoma, and 70 had normal eyes. We used automatic refractokeratometry, ultrasonic pachimetry, Goldmann applanation tonometry, and DCT measurements to investigate the effects of age, corneal astigmatism, refractive error, central corneal thickness (CCT), intraocular pressures (IOP), and ocular pulse amplitude (OPA) on DCT measurement quality (Q). Logistic regression analysis was used for statistical analysis.Results: For 159 patients, the DCT Q score was 1 (group 1). For the remaining 141 patients, the Q score was 2–3 (group 2). The following values were determined for the two groups, respectively: mean age 58.9±9.9 and 61.4±10.6; mean corneal astigmatisms −0.78±0.67 and −0.92±0.77 diopter; mean spherical equivalents 0.33±1.87 and −0.01±2.02 diopter; mean CCT 547.0±35.2 and 549±38.7 µm. Measurements with DCT provided mean IOPs of 18.5±3.70 and 21.27±6.19 mm Hg and mean OPA 3.5±1.4 and 3.2±1.2 mm Hg. By logistic regression analysis, we determined that the parameters affecting measurement quality were age, DCT measurement level, and OPA (p=0.015, p=0.000, and p=0.000, respectively).Conclusion: High IOP values, advanced age, and low OPA values can lead to decreased DCT measurement quality

External dacryocystorhinostomy: Single flap or double flaps anastomosis

Objective: To compare the the results of external dacryocystorhinostomyusing double flaps anastomosis andsingle flaps anastomosisMethods: Fifty-one eyes of 48 consecutive patients withcomplain epiphora and chronic dacryocystitis who hadundergone external dacryocystorhinostomy from October2009 to January 2012 were included. Single flap anastomosiswere performed on 26 eyes of 26 patients anddouble flaps anastomosis were performed on 25 eyes of22 patients and reviewed surgical success rate.Results: Silicon tube intubations were performed on13 eyes with single flaps anastomosis and 20 eyes withdouble flaps anastomosis. The mean length of follow-upwas 16.2±1.3 months for single flaps anastomosis groupand 18.1±2.1 months for double flaps anastomosis group.Success rates in single flap anastomosis group and doubleflaps anastomosis group were 92.4% and 96%, respectively.There was no statistically significant differencein success rate between the groups (p=0.088).Conclusion: Single flap and double flap anastomosisgave similar outcome in external dacryocystorhinostomysurgery.Key words: External dacryocystorhinostomy, single flap,double flap