Three-dimensional vascular imaging of proliferative diabetic retinopathy by Doppler optical coherence tomography

PURPOSE

To evaluate the 3-dimensional architecture of neovascularization in proliferative diabetic retinopathy using Doppler optical coherence tomography (OCT).

DESIGN

Prospective, nonrandomized clinical trial.

METHODS

Seventeen eyes of 14 patients with proliferative diabetic retinopathy were prospectively studied. Prototype Doppler OCT was used to evaluate the 3-dimensional vascular architecture at vitreoretinal adhesions.

RESULTS

Proliferative membranes were detected in all eyes with proliferative diabetic retinopathy by standard OCT images. Doppler OCT images detected blood flow by neovascularization of the disc in 12 eyes and neovascularization elsewhere in 11 eyes. Doppler OCT images showed the 3-dimensional extent of new vessels at various stages of neovascularization, and the extent of new vessels could be clearly confirmed at vitreoretinal adhesions.

CONCLUSIONS

Doppler OCT is useful for the detection and evaluation of the 3-dimensional vascular structure of neovascularization, and can assist in the noninvasive assessment of proliferative diabetic retinopathy.

Optically buffered Jones-matrix-based multifunctional optical coherence tomography with polarization mode dispersion correction

Polarization mode dispersion (PMD) degrades the performance of Jones-matrix-based polarization-sensitive multifunctional optical coherence tomography (JM-OCT). The problem is specially acute for optically buffered JM-OCT, because the long fiber in the optical buffering module induces a large amount of PMD. This paper aims at presenting a method to correct the effect of PMD in JM-OCT. We first mathematically model the PMD in JM-OCT and then derive a method to correct the PMD. This method is a combination of simple hardware modification and subsequent software correction. The hardware modification is introduction of two polarizers which transform the PMD into global complex modulation of Jones matrix. Subsequently, the software correction demodulates the global modulation. The method is validated with an experimentally obtained point spread function with a mirror sample, as well as by in vivo measurement of a human retina.

Two-dimensional micro-displacement measurement for laser coagulation using optical coherence tomography

To improve the reproducibility of photocoagulation, the ability to quantitatively monitor the thermal change of laser-irradiated retinal tissue is required. Recently, optical coherence tomography has enabled non-invasive and non-contact monitoring of the tissue structural changes during laser irradiation. To further improve the capability of this technique, a method is proposed to measure tissue displacement by simultaneously using Doppler phase shifts and correlation coefficients. The theoretical approach for this method is described, and its performance is experimentally confirmed and evaluated. Finally, lateral and axial displacements in the laser-irradiated retinal tissues of an enucleated porcine eye are observed. The proposed method is found to be useful for further understanding the direct thermal response of laser-irradiated retinal tissue.

Degree of polarization uniformity with high noise immunity using polarization-sensitive optical coherence tomography

A new metric representing polarization uniformity is presented. Noise corrected degree of polarization uniformity (DOPU) is computed from polarization-sensitive optical coherence tomography (OCT), and selectively visualizes tissue with the multiple scattering, such as highly pigmented tissues. The new metric is designed to be minimally sensitive to systematic additive noise. The performance of this new metric is analyzed by numerical simulation and in vivo human retinal imaging, using Jones matrix OCT. The new metric exhibited only a small dependency on the signal-to-noise ratio. Selective in vivo visualization of pigmented tissues in the human retina is demonstrated, with cross sectional and en-face images.

Complete mitochondrial genome of a natural triploid crucian carp mutant, Carassius auratus var. pingxiangnensis, and phylogenetic analysis of different ploidies in crucian carp

Carassius auratus var. pingxiangnensis is a natural triploid crucian carp mutant. In order to understand its placement and genetic background at the gene level, the characteristics of mitochondrial DNA sequences and phylogenetic relationship were examined. The results showed that the mitochondrial DNA is a circular double-stranded DNA molecule that is 16,576 bp in length with 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a non-coding control region. Mitochondrial genes overlapped by a total of 40 bp in 11 different locations from 1 to 14 bp. The base composition of the C. auratus mitogenome was estimated to be 29.70% A, 26.74% C, 15.35% G, and 28.21% T. The central conserved blocks and the conserved blocks were compared and were similar among C. auratus var. pingxiangnensis and six other cyprinids with different ploidies. The origin of light strand replication was similar to that of other vertebrates; it was 33 bp, but the characteristic sequence motif 5ꞌ-GCCGG-3ꞌ at the base of the stem within tRNA(Cys) was mutated to 5ꞌ-GGCGG- 3ꞌ. Our phylogenetic analysis based on whole mitogenome sequences indicated that C. auratus var. pingxiangnensis was clustered with C. auratus and then sister-grouped with Carassius gibelio. The systemic developmental tree of crucian carp with different chromosome ploidies showed that diploid C. auratus auratus was clustered with triploid C. auratus auratus, sister-grouped with tetraploid C. auratus auratus, and clustered with other diploid, triploid, and tetraploid C. auratus.

Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging

An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced JMT achieves a sufficiently long depth measurement range for clinical cases of posterior eye disease. Furthermore, a fine spectral shift compensation method based on the cross-correlation of calibration signals was devised for stabilizing the phase of OCT, which enables a high sensitivity Doppler OCT measurement. In addition, a new theory of JMT which integrates the Jones matrix measurement, Doppler measurement, and scattering measurement is presented. This theory enables a sensitivity-enhanced scattering OCT and high-sensitivity Doppler OCT. These new features enable the application of this system to clinical cases. A healthy subject and a geographic atrophy patient were measured in vivo, and simultaneous imaging of choroidal vasculature and birefringence structures are demonstrated.

Automated segmentation and characterization of choroidal vessels in high-penetration optical coherence tomography

An automated choroidal vessel segmentation and quantification method for high-penetration optical coherence tomography (OCT) was developed for advanced visualization and evaluation of the choroidal vasculature. This method uses scattering OCT volumes for the segmentation of choroidal vessels by using a multi-scale adaptive threshold. The segmented choroidal vessels are then processed by multi-scale morphological analysis to quantify the vessel diameters. The three-dimensional structure and the diameter distribution of the choroidal vasculature were then obtained. The usefulness of the method was then evaluated by analyzing the OCT volumes of normal subjects.

Three-dimensional retinal and choroidal capillary imaging by power Doppler optical coherence angiography with adaptive optics

Retinal and choroidal vascular imaging is a key to the better understanding and diagnosis of eye diseases. To achieve comprehensive three-dimensional capillary imaging, we used an enhanced vascular imaging technique, so called adaptive optics optical coherence angiography (AO-OCA). AO-OCA enables in vivo high-resolution and high-contrast micro-vascular imaging by detecting Doppler frequency shifts. Using this technique, the retinal and choroidal vasculatures of healthy subjects were imaged. The results show that both intensity and Doppler power images have sufficient contrast to discriminate almost all vasculatures from the static tissue. However, the choriocapillaris, pre-arterioles, and post-venules in the Sattler layer were more contrasted by the Doppler technique. In conclusion, AO-OCA enables three-dimensional capillary imaging, and is especially useful for the detection of the choriocapillaris and choroidal capillary network.

Passive component based multifunctional Jones matrix swept source optical coherence tomography for Doppler and polarization imaging

We present a fiber based multifunctional Jones matrix swept source optical coherence tomography (SS-OCT) system for Doppler and polarization imaging. Jones matrix measurement without using active components such as electro-optic modulators is realized by incident polarization multiplexing based on independent delay of two orthogonal polarization states and polarization diversity detection. In addition to polarization sensitivity, this system measures Doppler flow without extra hardware for phase stabilized SS-OCT detection. An eighth-wave plate was measured to demonstrate the polarization detection accuracy. The optic nerve head of a retina was measured in vivo. Detailed vasculature and birefringent structures were investigated simultaneously.

High-penetration swept source Doppler optical coherence angiography by fully numerical phase stabilization

A high-penetration swept-source optical coherence tomography (HP-SS-OCT) system based on a 1-μm short cavity laser is developed. Doppler OCT processing is applied, along with a custom-made numerical phase stabilization algorithm; this process does not require additional calibration hardware. Thus, our phase stabilization method is simple and can be employed in a variety of SS-OCT systems. The bidirectional blood flow and vasculature in the deep choroid was successfully imaged via two Doppler modes that use different time intervals for Doppler processing. En face projection image of squared power of Doppler shift is compared to ICGA, and the utility of our method is verified.

Clusterin synergizes with IL-2 for the expansion and IFN-γ production of natural killer cells

CLU is a secreted, multifunctional protein implicated in several immunologic and pathologic conditions. As the level of serum CLU was shown to be elevated during inflammatory responses, we questioned if CLU might interact with circulating lymphocytes leading to functional consequences. To assess this possibility directly, mouse splenocytes and purified NK cells were cultured with varying dose of CLU, and its effect on cell proliferation was examined. Our data showed that CLU up-regulated DNA synthesis and expansion of NK cells significantly in response to a suboptimal, but not maximal, dose of IL-2, and CLU alone did not exhibit such effects. This CLU-mediated synergy required the co-presence of CLU at the onset of IL-2 stimulation and needed a continuous presence during the rest of the culture. Importantly, NK cells stimulated with CLU showed increased formation of cell clusters and a CD69 activation receptor, representing a higher cellular activation status compared with those from the control group. Furthermore, these NK cells displayed elevated IFN-γ production upon RMA/S tumor target exposures, implying that CLU regulates not only NK cell expansion but also effector function of NK cells. Collectively, our data present a previously unrecognized function of CLU as a novel regulator of NK cells via providing costimulation required for cell proliferation and IFN-γ secretion. Therefore, the role of CLU on NK cells should be taken into consideration for the previously observed, diverse functions of CLU in chronic inflammatory and autoimmune conditions.

Differences in microstructural alterations of the hippocampus in Alzheimer disease and idiopathic normal pressure hydrocephalus: a diffusion tensor imaging study

BACKGROUND AND PURPOSE

DTI can be used to assess the degradation of WM tracts by measuring the FA and MD. Decreased FA/increased MD values in the AD hippocampus have been reported by many studies. In contrast, only a few studies reported on hydrocephalus by using the DTI technique. In elderly patients with dementia and with dilated ventricles, it is often difficult to differentiate iNPH from AD with visual measurements on MR imaging. The aim of this study was to investigate the changes of microstructural integrity of the hippocampus in iNPH by using DTI and determining whether this method could be a new diagnostic tool to differentiate iNPH from AD.

MATERIALS AND METHODS

We recruited 43 participants (15 healthy controls, 15 patients with AD, and 13 patients with iNPH). The FA and MD values were measured by using the region-of-interest method in the hippocampal head, body, and tail on both sides. Clinical history, neurologic examination, and neuropsychological assessment were included.

RESULTS

The FA values were the lowest in the patients with AD, the patients with iNPH, and the healthy controls in this order. The MD values were the highest in the same order. These findings were consistent in the 3 subdivisions of the bilateral hippocampal regions. Hippocampal volume was not different between patients with iNPH and AD.

CONCLUSIONS

The microstructural alterations of the hippocampus were more sensitive than the volumetric changes in AD and iNPH. DTI analysis might be a useful tool for discriminating AD from iNPH.

Dual enteric and respiratory tropisms of winter dysentery bovine coronavirus in calves

Although winter dysentery (WD), which is caused by the bovine coronavirus (BCoV) is characterized by the sudden onset of diarrhea in many adult cattle in a herd, the pathogenesis of the WD-BCoV is not completely understood. In this study, colostrum-deprived calves were experimentally infected with a Korean WD-BCoV strain and examined for viremia, enteric and nasal virus shedding as well as for viral antigen expression and virus-associated lesions in the small and large intestines and the upper and lower respiratory tract from 1 to 8 days after an oral infection. The WD-BCoV-inoculated calves showed gradual villous atrophy in the small intestine and a gradual increase in the crypt depth of the large intestine. The WD-BCoV-infected animals showed epithelial damage in nasal turbinates, trachea and lungs, and interstitial pneumonia. The WD-BCoV antigen was detected in the epithelium of the small and large intestines, nasal turbinates, trachea and lungs. WD-BCoV RNA was detected in the serum from post-inoculation day 3. These results show that the WD-BCoV has dual tropism and induces pathological changes in both the digestive and respiratory tracts of calves. To our knowledge, this is the first detailed report of dual enteric and respiratory tropisms of WD-BCoV in calves. Comprehensive studies of the dual tissue pathogenesis of the BCoV might contribute to an increased understanding of similar pneumoenteric CoV infections in humans.

Short term surgical outcomes of modified deep sclerectomy with catgut implant

We compared the effectiveness of and complications resulting from modified deep sclerectomy with catgut implant (modified-DSCI) with those of standard deep sclerectomy with collagen implant (DSCI) in the short term following surgery. In this retrospective study, standard-DSCI was performed on thirteen patients (17 eyes), and modified-DSCI was performed on seven patients (11 eyes). After dissection of a 5x5 mm sized superficial scleral flap, a 3x4 mm sized rectangular deep scleral flap was constructed in DSCI and a 2x3 mm sized triangular deep scleral flap in modified DSCI. A collagen implant was placed on the scleral bed in DSCI and # 0 CHROMIC Catgut Absorbable Suture was used in modified DSCI. The mean follow up was 11.0+/-6.1 months in DSCI and 9.3+/-4.7 months in modified DSCI. The mean preoperative intraocular pressure (IOP) was 38.6+/-10.9 mmHg in DSCI and 34.8+/-8.6 mmHg in modified DSCI. In the DSCI group, the IOP was 13.4+/-3.0 mmHg at final follow up, and was 11.4+/-3.2 mmHg in the modified DSCI group. The number of Nd:YAG goniopuncture was 3 cases (25%) in the modified DSCI group, and 3 cases (21.4%) in the DSCI group. The number of intraoperative microperforations was 3 in the DSCI group and 2 in the modified DSCI group. Temporary hypotony was encountered in 8 eyes (57.1%) of the DSCI group and 4 eyes (50%) of the modified DSCI group. There was no significant difference observed between the two groups in regards to the effectiveness or rate of complications seen during short term follow up.

Increased frequencies of glutathione S-transferase (GSTM1 and GSTT1) gene deletions in Korean patients with acquired aplastic anemia

Patients with reduced ability to metabolize environmental carcinogens or toxins may be at risk of developing aplastic anemia. Glutathione S-transferase (GST) has been implicated in detoxifying mutagenic electrophilic compounds. This study asked whether the homozygous gene deletions of GSTM1 and GSTT1 affect the likelihood of developing aplastic anemia. The incidence of GSTM1 and GSTT1 gene deletions was significantly higher for aplastic anemia patients (odds ratio [OR]: 3.1, P =.01 and OR: 3.1, P =.004, respectively) than for healthy controls. Among the aplastic anemia patients, 17.5% (10:57) had chromosomal abnormalities at the time of diagnosis, and all aplastic anemia patients with chromosomal abnormalities showed GSTT1 gene deletions (P =.048). Individuals with GSTM1 and GSTT1 gene deletions may have greater susceptibility to aplastic anemia. It is possible that genetic instability or chromosomal damage due to abnormal detoxification of environmental toxins might have worked as an important pathophysiologic mechanism of aplastic anemia for patients with GSTT1 gene deletions.

Surgical outcomes of deep sclerectomy with collagen implant

We evaulated the effectiveness and adverse effects of deep sclerectomy with collagen implant (DSCI), which is a kind of nonpenetrating filtering surgery. In this retrospective study, DSCI was performed in 15 eyes of 11 glaucoma patients. An trabeculo-Descemet's membrane (TDM) window is created by a deep sclerokeratectomy, and the collagen implant is placed in the sclera bed under a superficial flap (deep sclerectomy with collagen implant). In 3 of 15 eyes the DSCI was intraoperatively converted to conventional filtering surgery for a large perforation of the TDM. These eyes were not included in the results of the surgical outcomes. The mean age of the patients was 50.3 +/- 14.4 years, and the mean follow-up period was 11.1 +/- 5.9 months. A diagnosis of chronic open angle glaucoma was made in 7 eyes and a diagnosis of secondary glaucoma in 5 eyes. The mean preoperative IOP was 25.8 +/- 11.9 mmHg, the immediate postoperative IOP was 6.4 +/- 2.9 mmHg, and at the final follow-up, the IOP was 11.9 +/- 2.5 mmHg. The IOP in 5 eyes was under 6 mmHg temporarily. However, there was no serious complication such as shallow anterior chamber. DSCI is considered to be a good surgical procedure that has similar surgical outcomes to a conventional trabeculectomy without serious complications.

A case of glaucoma associated with Sturge-Weber syndrome and Nevus of Ota

The Sturge-Weber syndrome consists of a unilateral port-wine hemangioma of the skin along the trigeminal distribution and is accompanied by an ipsilateral leptomeningeal angioma. Glaucoma is present in approximately half of the cases. The Nevus of Ota is a melanocytic pigmentary disorder, most commonly involving the area innervated by the trigeminal nerve. Elevated intraocular pressure, with or without glaucomatous damage, is observed in 10% of the cases. We report the first case of glaucoma associated with Sturge-Weber syndrome and Nevus of Ota in Korea.

Restrictive cardiomyopathy in a patient with extrahepatic biliary atresia

The most commonly associated anomalies in patients with extrahepatic biliary atresia are cardiovascular, digestive and splenic defects. Of the cardiovascular anomalies, there are very few reports of biliary atresia with cardiomyopathy. We report the first case of a child with extrahepatic biliary atresia and restrictive cardiomyopathy. The patient was a 13-month-old boy diagnosed with extrahepatic biliary atresia at the age of 2 months, when he underwent laparotomy for definite diagnosis.Hepatic portoenterostomy was performed after confirmative cholangiogram. Recently, he developed severe cough and dyspnea, and his respiratory symptoms worsened. Chest radiograph showed cardiomegaly. Two- dimensional echocardiography showed marked biatrial enlargement. On M- mode echocardiogram, a slight increase in left ventricular dimension was seen in early diastole with a relatively good left ventricular function. Mitral inflow Doppler tracing showed an increased E-velocity (1.1 m/sec) with decreased deceleration time (75 m/sec), and increased E/A ratio (0.33). He was diagnosed as having restrictive cardiomyopathy with characteristic echocardiographic features.

Comparisons of intraocular-pressure- lowering efficacy and side effects of 2% dorzolamide and 1% brinzolamide

Forty-one healthy volunteers were recruited for a study to compare the intraocular pressure (IOP)-lowering efficacy and side effects of 2% dorzolamide and 1% brinzolamide. In a randomized double-blind design, one eye received one drop of 2% dorzolamide and the other eye received one drop of 1% brinzolamide. The IOP and side effects were evaluated by Goldmann applanation tonometry and slit lamp biomicroscopy before administration, and 3, 7 and 14 days after the initial administration of eyedrops. The IOP decreased significantly from baseline for both drugs (p < 0.05). However, there were no statistically significant differences between 2% dorzolamide and 1% brinzolamide either before or after eyedrop administration (p > 0.05). The most frequent side effect was ocular pain in the case of 2% dorzolamide and blurred vision in 1% brinzolamide. The results suggested that 2% dorzolamide and 1% brinzolamide have similar IOP-lowering efficacies with different side effects

Influence of glutathione S-transferase M1 and T1 genotypes on larynx cancer risk among Korean smokers

Glutathione S-transferase (GST) isoenzymes are involved in the detoxification of major carcinogens present in tobacco smoke. It is thus conceivable that deficiency in GST activity due to homozygous deletions of the GSTM1 and GSTT1 genes (the null genotypes) may modulate susceptibility to smoking-induced cancers. The influence of the GSTM1 and GSTT1 null genotypes on larynx cancer risk among the Korean population were evaluated using peripheral blood DNA from 82 larynx cancer patients and 63 healthy controls, all of whom were male current smokers. Increased larynx cancer risk was related to the GSTM1 null genotype (odds ratio (OR)=3.53, 95% confidence interval (CI)=1.27-9.83). The OR associated with the GSTT1 null genotype was also increased, but did not reach statistical significance (OR=1.83, 95% CI=0.70-4.79). Individuals lacking both the GSTM1 and GSTT1 genes were at a significantly higher risk for larynx cancer than individuals with both genes present (OR=4.04, 95% CI=1.33-12.30). These data confirm that the GSTM1 null genotype is an important risk modifier for larynx cancer among Korean smokers and combined GSTM1 and GSTT1 null genotypes could be a useful predictor of genetic susceptibility to larynx cancer.

Clinical usefulness of serum and plasma vascular endothelial growth factor in cancer patients: which is the optimal specimen?

Vascular endothelial growth factor (VEGF) is secreted by various human cancer cells and plays a key role in cancer angiogenesis and metastasis. Recently, evidence of VEGF storage in blood cells including platelets has been reported. The serum VEGF levels were reported to increase during clotting as a result of its release from platelets, and plasma sample instead of serum was recommended for measuring the circulating VEGF more accurately. However, platelets have been implicated in tumor metastasis since circulating tumor cells forming aggregates with platelets were observed. The purpose of this study was to clarify which is an optimal specimen to measure VEGF in cancer patients, serum or plasma. We measured serum and plasma VEGF levels and platelet counts in 173 cancer patients and 42 healthy people, and found that serum VEGF levels were significantly higher than matched plasma VEGF and the VEGF difference (serum VEGF - plasma VEGF) correlated with platelet counts (r=0.624, p<0.05) in both cancer patients and healthy controls. We selected cancer patients with normal platelet counts (130-400x103/microl, Plt-normal cancer group). Interestingly, serum VEGF levels were higher in Plt-normal cancer group than in healthy controls. The theoretical platelet-derived VEGF in serum, calculated based on actual blood platelet counts (pg per 106 platelets), was also significantly higher in Plt-normal cancer group than in normal controls. It is, therefore, suggested that, although the serum VEGF levels are affected by blood platelets, platelet-derived VEGF also reflect biology of cancer cells, and that serum would be the more useful specimen for measurement of circulating VEGF in cancer patients for prognosis.