Bubble cascade in Guinness beer is caused by gravity current instability.

The downward movement of the bubble-texture in a glass of Guinness beer is a fascinating fluid flow driven by the buoyant force of a large number of small-diameter bubbles. This texture motion is a frequently observed phenomenon on pub tables. The physical mechanism of the texture-formation has been discussed previously, but inconsistencies exist between these studies. We performed experiments on the bubble distribution in Guinness poured in an inclined container, and observed how the texture forms. We also report the texture-formation in controllable experiments using particle suspensions with precisely specified diameters and volume-concentrations. Our specific measurement methods based on laser-induced-fluorescence provide details of the spatio-temporal profile of the liquid phase velocity. The hydrodynamic condition for the texture-formation is analogous to the critical point of the roll-wave instability in a fluid film, which can be commonly observed in water films sliding downhill on a rainy day. Here, we identify the critical condition for the texture-formation and conclude that the roll-wave instability of the gravity current is responsible for the texture-formation in a glass of Guinness beer.

Caffeine adsorption of montmorillonite in coffee extracts.

The growth in health-conscious consumers continues to drive the demand for a wide variety of decaffeinated beverages. We previously developed a new technology using montmorillonite (MMT) in selective decaffeination of tea extract. This study evaluated and compared decaffeination of coffee extract using MMT and activated carbon (AC). MMT adsorbed caffeine without significant adsorption of caffeoylquinic acids (CQAs), feruloylquinic acids (FQAs), dicaffeoylquinic acids (di-CQAs), or caffeoylquinic lactones (CQLs). AC adsorbed caffeine, chlorogenic acids (CGAs) and CQLs simultaneously. The results suggested that the adsorption selectivity for caffeine in coffee extract is higher in MMT than AC. The caffeine adsorption isotherms of MMT in coffee extract fitted well to the Langmuir adsorption model. The adsorption properties in coffee extracts from the same species were comparable, regardless of roasting level and locality of growth. Our findings suggest that MMT is a useful adsorbent in the decaffeination of a wide range of coffee extracts.

Organoclays in water cause expansion that facilitates caffeine adsorption.

This study investigates the adsorption of caffeine in water on organically modified clays (a natural montmorillonite and synthetic saponite, which are smectite group of layered clay minerals). The organoclays were prepared by cation-exchange reactions of benzylammonium and neostigmine with interlayer exchangeable cations in the clay minerals. Although less caffeine was uptaken on neostigmine-modified clays than on raw clay minerals, uptake was increased by adding benzylammonium to the clays. The adsorption equilibrium constant was considerably higher on benzylammonium-modified saponite (containing small quantities of intercalated benzylammonium) than on its montmorillonite counterpart. These observations suggest that decreasing the size and number of intercalated cations enlarges the siloxane surface area available for caffeine adsorption. When the benzylammonium-smectite powders were immersed in water, the intercalated water molecules expanded the interlayer space. Addition of caffeine to the aqueous dispersion further expanded the benzylammonium-montmorillonite system but showed no effect on benzylammonium-saponite. We assume that intercalated water molecules were exchanged with caffeine molecules. By intercalating benzylammonium into smectites, we have potentially created an adaptable two-dimensional nanospace that sequesters caffeine from aqueous media.

Visual outcome after intravitreal triamcinolone acetonide depends on optical coherence tomographic patterns in patients with diffuse diabetic macular edema.

PURPOSE: To evaluate the effectiveness of intravitreal triamcinolone acetonide (IVTA) on the reduction of diffuse diabetic macular edema with different optical coherence tomographic patterns. METHODS: One hundred and thirty-five eyes with diffuse diabetic macular edema without any treatment that had received a single dose (4 mg in 0.1 mL) of IVTA were retrospectively examined. Each preoperative macular optical coherence tomographic image was classified according to its appearance as follows: sponge-like diffuse retinal thickening, cystoid macular edema (CME), and serous retinal detachment (SRD). Central macular thickness with optical coherence tomographic images and visual acuity with a logarithm of the minimum angle of resolution chart were assessed at 3 months postoperatively. RESULTS: Of 135 eligible eyes, 49 eyes were identified as having only sponge-like diffuse retinal thickening, 45 eyes with CME, and 26 eyes with SRD. Of those 135 eyes, 15 eyes exhibited the combination of all types of diffuse diabetic macular edema, defined as FULL. After IVTA, central macular thickness was reduced to 31.0 ± 15.9% in the sponge-like diffuse retinal thickening, 40.7 ± 14.2% in the CME, 23.4 ± 15.0% in the SRD, and 25.8 ± 14.8% in the FULL group (P < 0.001; one-factor analysis of variance), while improvement in logarithm of the minimum angle of resolution visual acuity was -0.26 ± 0.21 in the sponge-like diffuse retinal thickening, -0.32 ± 0.20 in the CME, -0.17 ± 0.20 in the SRD, and -0.14 ± 0.22 in the FULL group (P = 0.018; one-factor analysis of variance). CONCLUSION: The effectiveness of IVTA on diffuse diabetic macular edema was dependent on the optical coherence tomographic pattern, and IVTA was found to be more effective in patients with CME, while IVTA was less effective in those with SRD.

Diclofenac prevents temporal increase of intraocular pressure after uneventful cataract surgery with longer operation time.

PURPOSE: This study compares the effect of topical diclofenac with that of betamethasone against postoperative increase of intraocular pressure (IOP) after cataract surgery in normal patients, and also investigated the risk factors for postoperative increase of IOP in each group. METHODS: Fifty consecutive patients without systemic disease who have bilateral and symmetrical cataracts underwent uncomplicated cataract surgery in both eyes (100 eyes in total). Postoperatively, topical diclofenac was applied 4 times daily to one eye, and topical betamethasone to the other eye in each patient. IOP and best corrected logMAR visual acuity (BCVA) in each eye were measured up to 8 weeks. Total surgery time and effective phacoemulsification time (EPT) for each case was recorded. RESULTS: BCVA in both diclofenac- and betamethasone-treated eyes significantly improved after the cataract surgery; however, no statistical difference in VA was noted between the diclofenac- and betamethasone-treated eyes throughout the observation period. IOP in the diclofenac-treated eyes decreased with time, in contrast to the IOP in the betamethasone-treated eyes, which showed a slight increase. At 4 and 8 weeks postoperatively, there was significant difference between these two eye groups. Multiple regression analysis revealed that postoperative increase in IOP at 8 weeks in the betamethasone-treated eyes was closely correlated with total surgery time and EPT, but the IOP in the diclofenac-treated eyes showed no correlation with any surgical or clinical parameters. CONCLUSIONS: Postoperative increase in IOP after cataract surgery was affected by total surgery time and EPT in the betamethasone-treated eye. The time for surgery and EPT is longer in complicated cases including patients with a hard nucleus or small pupils, and also longer for beginning surgeons and in older patients. In these cases, diclofenac in place of betamethasone as a postoperative topical antiinflammatory drug is recommended for the prevention of postoperative increase in IOP.

Panretinal photocoagulation induces pro-inflammatory cytokines and macular thickening in high-risk proliferative diabetic retinopathy.

PURPOSE: To investigate whether pan-retinal photocoagulation (PRP) affects vitreous levels of cytokines and macular thickening in patients with high-risk proliferative diabetic retinopathy (PDR). METHODS: Fourteen patients with bilateral high-risk PDR--which requires pars plana vitrectomy (PPV)--but without a history of retinal photocoagulation participated in this study. Before PPV, one eye received PRP, and the other eye did not. The concentrations of cytokines of vascular endothelial growth factor (VEGF), stromal derived factor-1 (SDF-1), interleukin-6 (IL-6) and regulated upon activation, normal T-cell expressed and secreted (RANTES) were measured in each vitreous sample obtained at PPV. Macular thickness obtained by optical coherence tomography was also monitored during clinical course. RESULTS: After the PRP, macular thickness in PRP-pretreated eye showed temporal increase. Vitreous levels of IL-6 and RANTES in PRP pre-treated eye were significantly higher than levels in control eyes (p = 0.013, p = 0.033). Although macular thickness in control was correlated to vitreous levels of VEGF and IL-6 (p = 0.022, p = 0.003), that in PRP-pretreated eye was closely correlated to IL-6 and RANTES (p = 0.002, p = 0.011). After the PPV, macular thickness in both eye groups improved, and there was no significant difference between both eye groups 3 months after the PPV. CONCLUSIONS: In patients with high-risk PDR, PRP cause temporal worsening of macular edema linked with pro-inflammatory cytokines of IL-6 and RANTES, but not with VEGF and SDF-1. Thus, PRP-induced macular edema was caused by inflammation, while visual prognosis after PPV was not influenced by pretreatment of PRP.

Drug reflux during posterior subtenon infusion of triamcinolone acetonide in diffuse diabetic macular edema not only brings insufficient reduction but also causes elevation of intraocular pressure.

BACKGROUND: At the time of posterior subtenon infusion of triamcinolone acetonide (STI-TA) in patients with diabetic macular edema (DME), drug reflux of TA has sometimes been observed from the conjunctival incision site. We investigated the influence of this reflux on regression of DME and postoperative intraocular pressure (IOP). METHODS: STI-TA was performed on one hundred and twenty-four eyes of 88 consecutive patients with DME. Eligible eyes were divided into two groups: those with observed drug reflux of TA and those without observed drug reflux of TA. Visual acuity (VA), foveal thickness (FT) and IOP were monitored in each eye for up to 12 weeks after STI-TA. RESULTS: STI-TA with drug reflux was observed in ten individual eyes of seven patients. These patients were significantly younger than those patients without observed drug reflux. After STI-TA, both improvement of VA and regression of FT in reflux(+) eyes were less than in reflux(-) eyes. Postoperative IOP elevation in reflux(+) eyes was much higher, and four of the ten eyes needed anti-glaucoma therapy. This was in contrast to three of the 118 eyes without drug reflux that required anti-glaucoma therapy. CONCLUSIONS: At the time of STI-TA in DME, drug reflux of TA is a risk factor not only for insufficient reduction of edema, but also for postoperative IOP elevation.

Comparative therapy evaluation of intravitreal bevacizumab and triamcinolone acetonide on persistent diffuse diabetic macular edema.

PURPOSE: To compare the effect of an intravitreal injection of bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, with that of triamcinolone acetonide, a corticosteroid for reduction of diabetic macular edema (DME). DESIGN: Prospective, comparative interventional case series. METHODS: Twenty-eight eyes of 14 patients with bilateral DME participated in this study. In each patient, one eye received an intravitreal injection of 4 mg triamcinolone acetonide and the other eye received 1.25 mg bevacizumab. The clinical course of best-corrected visual acuity (VA) with a logarithm of the minimum angle of resolution chart and averaged foveal thickness using optical coherence tomography was monitored for up to 24 weeks after the injection. RESULTS: Before the injection, foveal thickness and VA were 522.3 +/- 91.3 microm and 0.64 +/- 0.28 microm in the triamcinolone-injected eye, and 527.6 +/- 78.8 microm and 0.61 +/- 0.18 microm in the bevacizumab-injected eye, respectively; there was no significant difference between the eyes. One week after the injection, both eyes showed significant regression of macular edema. The triamcinolone-injected eye (342.6 +/- 85.5 microm and 0.33 +/- 0.21 microm) showed significantly better results than the bevacizumab-injected eye (397.6 +/- 103.0 microm and 0.37 +/- 0.17 microm). However, both eyes showed the recurrence of macular edema with time, even at 24 weeks. Triamcinolone (410.4 +/- 82.4 microm and 0.47 +/- 0.25 microm) kept better results than bevacizumab (501.6 +/- 92.5 microm and 0.61 +/- 0.17 microm). CONCLUSIONS: With the generally used concentration, intravitreal injection of triamcinolone acetonide showed better results in reducing DME and in the improvement of VA than that of bevacizumab, suggesting that the pathogenesis of DME is not only attributable to VEGF-dependency, but is also attributable to other mechanisms suppressed by corticosteroid.

Visual prognosis and vitreous cytokine levels after arteriovenous sheathotomy in branch retinal vein occlusion associated with macular oedema.

PURPOSE: To investigate the relationship between vitreous levels of cytokines, including interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF), and visual prognosis after pars plana vitrectomy (PPV) with arteriovenous sheathotomy in patients with branch retinal vein occlusion (BRVO) associated with macular oedema. METHODS: We studied 60 patients with logMAR visual acuity (VA) scores of < 0.3 and visual impairment secondary to BRVO-associated macular oedema. All patients underwent PPV with arteriovenous sheathotomy. At the time of PPV, vitreous samples were collected from the operated eye and vitreous levels of VEGF and IL-6 were measured. Best corrected VA (BCVA) (using a logMAR chart) and foveal thickness (FT) (using optical coherence tomography) were monitored for up to 6 months after PPV. RESULTS: Both BCVA and FT significantly improved after PPV. According to multiple regression analysis, both the improvement in BCVA and decrease in FT were closely related to the vitreous level of IL-6 but not to that of VEGF. The vitreous level of VEGF was strongly correlated with duration of BRVO. CONCLUSIONS: Both improvement in BCVA and decrease in FT were observed after PPV in BRVO patients with macular oedema. Interestingly, these visual prognoses strongly correlate with the vitreous level of IL-6, whereas the duration of BRVO strongly correlates with the vitreous level of VEGF.

Pretreatment of posterior subtenon injection of triamcinolone acetonide has beneficial effects for grid pattern photocoagulation against diffuse diabetic macular oedema.

AIM: To prospectively evaluate the efficacy of subtenon injection of triamcinolone acetonide (TA) before laser grid pattern photocoagulation (G-PC) for the treatment of diffuse diabetic macular oedema (DDME). METHODS: 42 eyes of 37 consecutive patients with DDME were studied. 1 week before G-PC, 21 eyes received TA subtenon injection, and the other eyes served as control. The clinical course of visual acuity (VA) and foveal thickness (FT) was monitored for up to 24 weeks after G-PC. Mean deviation (MD) of perimetry with 30-2 program on Humphrey Perimeter (Zeiss-Humphrey, Dublin, California, USA) was also measured. The average laser intensity was recorded. RESULTS: After TA injection, FT and VA were improved, and subsequent G-PC maintained the improvement for up to 24 weeks without recurrence of diffuse diabetic macular oedema. In contrast, G-PC without TA injection induced transient worsening of FT and VA, then both were gradually improved. At 24 weeks after G-PC, MD in the TA-injected eyes was better than those in control. The required laser intensity in TA-injected eyes was less than that for control. CONCLUSION: Subtenon injection of TA prior to G-PC allows for treatment with a lower intensity of laser spots and also prevents the decrease in central visual field sensitivity, all of which have clinical advantages for G-PC.

Panretinal-Photocoagulation before Pars Plana Vitrectomy Influences Vitreous Level of Interleukin-6 but not of Vascular Endothelial Growth Factor in Patients with Diabetic Retinopathy.

For eyes with diabetic retinopathy which require vitreous surgery and pan-retinal photocoagulation (PRP), pre-treatment of PRP before vitreous surgery reduce the activity of diabetic retinopathy, however sometimes cause macular edema leading to visual disturbance. Some cytokines in the vitreous increase in eyes with diabetic macular edema, thus the relationship between PRP and vitreous cytokines is to be investigated. In this study, 72 eligible eyes of 65 patients were recruited, and 36 eyes had pre-treatment of PRP before vitreous surgery. The other 36 eyes were served as control which had PRP not before but under surgery. There was no statistical significant difference of systemic conditions between two groups. All eyes had pars plana vitrectomy, and 1 ml of vitreous sample was obtained under the surgery. Vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in the vitreous sample were measured in each case. After the completion of pre-treatment of PRP, macular edema defined as increase of foveal thickness was prominently worsened, and the vitreous level of IL-6 in PRP pre-treated group showed statistically higher than that in control. In contrast, there was no significant difference of VEGF level between two groups. While, vitreous level of VEGF in control group was strongly correlated with grade of retinopathy and duration of diabetes. In conclusion, PRP influenced vitreous level of IL-6 but not VEGF, leading to macular edema, which suggests that IL-6 plays critical roles of PRP induced macular edema.

Posterior sub-Tenon's capsule injection of triamcinolone acetonide prevents panretinal photocoagulation-induced visual dysfunction in patients with severe diabetic retinopathy and good vision.

PURPOSE: To evaluate prospectively the efficacy of a single sub-Tenon's capsule injection of triamcinolone acetonide (TA) against panretinal photocoagulation (PRP)-induced macular thickening and visual disturbance in patients with severe diabetic retinopathy and good vision. DESIGN: Prospective, comparative, interventional case series. PARTICIPANTS: Twenty eyes of 10 patients with severe nonproliferative diabetic retinopathy or non-high-risk proliferative diabetic retinopathy whose visual acuity was 20/40 or better (<0.3 in logarithm of the minimum angle of resolution [logMAR] acuity) before the PRP, whose retinopathy was bilateral and symmetrical. The averaged parafoveal retinal thickness was more than 300 microm, leading to a worse visual prognosis after PRP. INTERVENTION: Sub-Tenon's capsule injection of 20 mg TA. MAIN OUTCOME MEASURES: Best-corrected visual acuity (BCVA) with logMAR chart and averaged foveal thickness (FT) using the retinal mapping program of optical coherence tomography. METHODS: In all patients, PRP was performed every other week for 4 sessions on both eyes, and 1 week before PRP; 1 eye received the TA injection, and the other eye served as a control. The clinical course of BCVA and FT was monitored for up to 24 weeks after beginning PRP. RESULTS: Before TA injection, BCVA and FT were 0.055+/-0.072 and 235.5+/-37.5 microm in the TA-injected eye and 0.065+/-0.071 and 233.7+/-39.8 microm in the control eye, respectively; there was no significant difference between eyes. After the TA injection, FT in the TA-injected eyes was significantly decreased. During and after the PRP, FT in the control eye increased dramatically and reached 312.0+/-68.2 microm at 24 weeks, which was significantly different from that in the TA-injected eyes (235.3+/-38.6 microm at 24 weeks). Best-corrected visual acuity in the control eye decreased with time to 0.24+/-0.13; in contrast, and BCVA in the TA-injected eye was good (to 0.085+/-0.11) . CONCLUSIONS: As a pretreatment for PRP, a single sub-Tenon's capsule injection of TA has beneficial effects for preventing PRP-induced foveal thickening and visual dysfunction in patients with severe diabetic retinopathy and good vision.

Novel 615delC mutation in the CRX gene in a Japanese family with cone-rod dystrophy.

PURPOSE: To characterize the clinical features of a Japanese family with cone-rod dystrophy associated with a novel 615delC mutation in the cone-rod homeobox (CRX) gene. DESIGN: Case reports and results of DNA analysis. METHODS: Mutational screening by direct sequencing was performed for the three exons in the CRX gene. The clinical features were evaluated by visual acuity measurements, electroretinography, and kinetic visual field testing. RESULTS: A 615delC mutation in the CRX gene was identified and found to cosegregate with cone-rod dystrophy. The ophthalmic findings included cone-rod dystrophy with negative-type electroretinograms (ERGs) and a rapid progression after the age of 40 years. CONCLUSION: These findings indicate that the 615delC mutation causes cone-rod dystrophy with a negative-type ERG. The genotype-phenotype correlation in the CRX gene in our patient and others reported in the literature suggest that the negative-type ERG might be a good sign for having a mutation in the CRX gene.