Flavonoids in the flowers of Primula ×polyantha Mill. and Primula primulina (Spreng.) H. Hara (Primulaceae).

Two undescribed anthocyanins and two undescribed flavonols were isolated from the flowers of Primula ×polyantha Mill., along with five known anthocyanins and four known flavonols. The two undescribed anthocyanins and the two undescribed flavonols were determined to be hirsutidin 3-O-ß-galactopyranoside-5-O-ß-glucopyranoside, 7-O-methyl-petunidin 3-O-ß-galactopyranoside-5-O-ß-glucopyranoside, quercetin 3-O-ß-[(6""-acetylglucopyranosyl)-(1 â†’ 2)-ß-glucopyranosyl-(1 â†’ 6)-ß-glucopyranoside], and kaempferol 3-O-ß-[(6""-acetylglucopyranosyl)-(1 â†’ 2)-ß-glucopyranosyl-(1 â†’ 6)-ß-glucopyranoside] using chemical and spectroscopic methods. They were also found in the flowers of the Himalayan wild species, Primula primulina (Spreng.) H. Hara except for quercetin 3-O-ß-[(6""-acetylglucopyranosyl)-(1 â†’ 2)-ß-glucopyranosyl-(1 â†’ 6)-ß-glucopyranoside]. The flower color variations of P. ×polyantha cultivars, reflected by the hue values (b*/a*) of the colors, were due to the glycosidic patterns in the anthocyanins and their concentrations in the petals. Moreover, in the P. ×polyantha cultivars with violet-blue flowers, both the intermolecular copigmentation occurs between hirsutidin 3-O-ß-galactopyranoside-5-O-ß-glucopyranoside and another flavonol, quercetin 3-O-ß-glucopyranosyl-(1 â†’ 2)-ß-glucopyranosyl-(1 â†’ 6)-ß-glucopyranoside. Moreover, the flower color variation was affected by the pH value.

Correlation between metamorphopsia and disorganization of the retinal inner layers in eyes with diabetic macular edema.

PURPOSE: To investigate factors associated with the severity of metamorphopsia secondary to diabetic macular edema (ME) by evaluating optical coherence tomography (OCT) parameters including disorganization of the retinal inner layers (DRIL). METHODS: We retrospectively reviewed medical records of 37 eyes of 37 consecutive patients with diabetic ME or resolved diabetic ME, who underwent spectral-domain OCT examination and metamorphopsia assessment with M-CHARTS on the same day between November 2017 and March 2018. Age, sex, visual acuity, lens status, treatment history, and factors analyzed on OCT examination including DRIL length were evaluated in association with M-CHARTS scores. RESULTS: Metamorphopsia was detected in 20 eyes (54%). The patients with metamorphopsia were relatively older than those without it (P = 0.060), and DRIL length was relatively longer in eyes with metamorphopsia (P = 0.065), while visual acuity was significantly better in eyes without metamorphopsia (P = 0.048). In correlation analyses to the severity of metamorphopsia, the DRIL length was the only OCT parameter associated with the M-CHARTS score (P = 0.035), while age, visual acuity, and ME were not significantly associated with the severity of metamorphopsia (P = 0.051, 0.060, and 0.344, respectively). CONCLUSION: The DRIL length was significantly associated with the severity of metamorphopsia secondary to diabetic ME. The inner retinal layer plays a key role in the development of metamorphopsia in eyes with diabetic ME. Metamorphopsia should be carefully considered when treating diabetic ME since its severity has been found to be independent of visual acuity and ME status.

Disorganization of the Retinal Inner Layers after Anti-VEGF Treatment for Macular Edema due to Branch Retinal Vein Occlusion.

PURPOSE: To evaluate the association between disorganization of the retinal inner layers (DRIL) and visual acuity (VA) after anti-VEGF treatment for macular edema (ME) due to branch retinal vein occlusion (BRVO). METHODS: Sixty eyes of 60 patients were retrospectively investigated. Baseline characteristics and factors analyzed on optical coherence tomography (OCT) examination at the final visit were evaluated in association with VA at the final visit. RESULTS: DRIL was detected in 39 eyes at the final visit. The central subfield thickness was significantly higher in the eyes with DRIL. While DRIL length at the final visit showed a significant association with final VA on univariable analysis, only age and ellipsoid zone disruption on OCT at the final visit were found to be significantly associated with VA on multivariable analysis. CONCLUSIONS: DRIL had only a minor role in determining VA after anti-VEGF treatment for ME due to BRVO.

Floating flap of internal limiting membrane in myopic macular hole surgery.

PURPOSE: To evaluate the surgical results of macular hole (MH) in patients with high myopia treated with pars plana vitrectomy (PPV) leaving the internal limiting membrane (ILM) flap floating in vitreous fluid at the edge of the MH. METHODS: Nine highly myopic eyes with MH of nine consecutive patients who underwent PPV were retrospectively evaluated. Three eyes were accompanied by retinal detachment (RD). ILM peeling was performed around the MH and some part of the ILM flap was left attached to the edge of the MH. Further manipulation of the ILM flap to cover the MH was not performed. Fluid-gas exchange was performed to the retinal vessel arcade level. Patients maintained a face down position for 3 to 7 days postoperatively. RESULTS: Complete MH closure was confirmed using optical coherence tomography in all eyes and three eyes with RD showed reattachment of the retina after the initial surgery. Visual acuity significantly improved (P = 0.02) and no eyes experienced MH reopening or RD occurrence during the follow-up period of 8.33 ± 3.61 months after the surgery. CONCLUSIONS: MH with or without RD in highly myopic eyes could be successfully treated with PPV leaving ILM flap floating in vitreous fluid at the edge of the MH. After the ILM peeling, further manipulation of the ILM flap to cover the MH would not be necessary for the treatment of MH in high myopia.

High dietary fat-induced obesity in Wistar rats and type 2 diabetes in nonobese Goto-Kakizaki rats differentially affect retinol binding protein 4 expression and vitamin A metabolism.

Obesity is a major risk factor for type 2 diabetes, which is caused mainly by insulin resistance. Retinol binding protein 4 (RBP4) is the only specific transport protein for retinol in the serum. RBP4 level is increased in the diabetic state and high-fat condition, indicating that retinol metabolism may be affected under these conditions. However, the precise effect of diabetes and high fat-induced obesity on retinol metabolism is unknown. In this study, we examined differences in retinol metabolite levels in rat models of diet-induced obesity and type 2 diabetes (Goto-Kakizaki [GK] rat). Four-week-old male Wistar and GK rats were given either a control diet (AIN-93G) or a high-fat diet (HFD, 40% fat kJ). After 15 weeks of feeding, the RBP4 levels increased by 2-fold in the serum of GK rats but not HFD-fed rats. The hepatic retinol concentration of HFD-fed rats was approximately 50% that of the controls (P < .01). In contrast, the renal retinol concentrations of GK rats increased by 70% (P < .01). However, expression of RARß in the kidney, which was induced in a retinoic acid-dependent manner, was downregulated by 90% (P < .01) in GK rats. In conclusion, diabetes and obesity affected retinol metabolism differently, and the effects were different in different peripheral tissues. The impact of HFD may be limited to the storage of hepatic vitamin A as retinyl palmitate. In particular, our data indicate that renal retinoic acid production might represent an important target for the treatment of type 2 diabetes mellitus.

Hemodialysis Associated with Severe and Unpredictable Hypoglycemia.

We herein report the case of a 68-year-old man receiving hemodialysis who developed severe hypoglycemia. He became unconscious and exhibited a blood glucose level below 10 mg/dL. We ruled out the possibility of other causes; however, severe hypoglycemia was observed even after starting glucose injections. The patient developed pneumonia and finally died. Although we conducted an autopsy, there were no specific findings explaining the severe hypoglycemia. We believe that carnitine deficiency was possibly involved in the severe hypoglycemia observed in this case. Physicians should be aware of the possibility of carnitine deficiency and/or severe hypoglycemia, especially in hemodialysis patients with malnutrition.

Subfoveal serous retinal detachment associated with extramacular branch retinal vein occlusion.

PURPOSE: To study the pathophysiology of subfoveal serous retinal detachment (SRD) observed in eyes with extramacular branch retinal vein occlusion (BRVO). METHODS: We retrospectively reviewed the medical records of nine patients (nine eyes) with extramacular BRVO with macular complications that were examined using optical coherence tomography (OCT). RESULTS: Extramacular BRVO was observed in the inferior area in three eyes, in the superior area in five eyes, and in the nasal area in one eye. Visual acuity was moderately disturbed (median, 0.6; range, 0.2-0.9, measured using the Landolt chart). One eye showed extensive SRD that was connected to the area affected by BRVO through the subretinal space. In eight of the eyes, focal SRD was observed beneath the fovea without subretinal connections to the area affected by BRVO. However, all these eyes showed marked retinal swelling in the outer retina, particularly in the outer plexiform layer. In two of the eyes, detailed OCT examinations showed a small break on the external surface of the retina connecting the swollen outer retina with the underlying SRD. All eyes showed hyperreflective foci in the outer retina, most frequently along the inner boundary of the outer plexiform layer and external limiting membrane. CONCLUSION: Extramacular BRVO is often accompanied by focal SRD beneath the fovea. Leakage from the retinal capillaries affected by BRVO travelled via the outer plexiform layer and caused SRD under the fovea.

Protein fluctuations as the possible origin of the thermal activation of rod photoreceptors in the dark.

Efficient retinal photoisomerization, signal transduction, and amplification contribute to single-photon electrical responses in vertebrates visual cells. However, spontaneous discrete electrical signals arising in the dark, with identical intensity and time profiles as those generated by genuine single photons (dark events), limit the potential capability of the rod visual system to discern single photons from thermal noise. It is accepted that the light and the thermal activation of the rod photoreceptor rhodopsin (Rho) triggers the light and the dark events, respectively. However the activation barrier for the dark events (80-110 kJ/mol) appears to be only half of the barrier for light-dependent activation of Rho (> or =180 kJ/mol). On the basis of these observations, it has been postulated that both processes should follow different pathways, but the molecular mechanism for the thermal activation process still remains an open question and subject of debate. Here, performing infrared difference spectroscopy measurements, we found that the -OH group of Thr118 from bovine Rho exhibits a slow but measurable hydrogen/deuterium exchange (HDX) under native conditions. Given the location of Thr118 in the X-ray structures, isolated from the aqueous phase and in steric contact with the buried retinal chromophore, we assume that a protein structural fluctuation must drive the retinal binding pocket (RBP) transiently open. We characterized the kinetics (rate and activation enthalpy) and thermodynamics (equilibrium constant and enthalpy) of this fluctuation from the global analysis of the HDX of Thr118-OH as a function of the temperature and pH. In parallel, using HPLC chromatography, we determined the kinetics of the thermal isomerization of the protonated 11-cis retinal in solution, as a model for retinal thermal isomerization in an open RBP. Finally, we propose a quantitative two-step model in which the dark activation of Rho is triggered by thermal isomerization of the retinal in a transiently opened RBP, which accurately reproduced both the experimental activation barrier and the rate of the dark events. We conclude that the absolute sensitivity threshold of our visual system is limited by structural fluctuations of the chromophore binding pocket rather than in the chromophore itself.

Structural changes in the Schiff base region of squid rhodopsin upon photoisomerization studied by low-temperature FTIR spectroscopy.

Low-temperature Fourier transform infrared (FTIR) spectroscopy is used to study squid rhodopsin at 77 K in investigating structural changes in the Schiff base region upon photoisomerization. The analysis of O-D stretching vibrations in D(2)O revealed that there are more internal water molecules near the retinal chromophore in squid rhodopsin than in bovine rhodopsin. Among nine O-D stretching vibrations of water in squid rhodopsin, eight peaks are identical between rhodopsin and 9-cis-rhodopsin (Iso). On the other hand, the isomer-specific O-D stretch of water was observed for rhodopsin (2451 cm(-)(1)) and Iso (2382 cm(-)(1)). Low frequencies of these bands suggest that the water forms a strong hydrogen bond with a negatively charged counterion. In addition, it was suggested that the hydrogen bond of the Schiff base is weaker in squid rhodopsin than in bacteriorhodopsin and bovine rhodopsin, and squid rhodopsin possessed similar hydrogen bonding strength for the Schiff base among rhodopsin, Iso, and bathorhodopsin. Most vibrational bands in the X-D stretch region originate from water O-D or the Schiff base N-D stretches, suggesting that the hydrogen bonding network in the Schiff base region of squid rhodopsin is composed of only water molecules. On the basis of these results, we propose that squid rhodopsin possesses a "bridge" water between the Schiff base and its counterion as well as squid retinochrome [Furutani, Y., Terakita, A., Shichida, Y., and Kandori, H. (2005) Biochemistry 44, 7988-7997], which is absent in vertebrate rhodopsin [Furutani, Y., Shichida, Y., and Kandori, H. (2003) Biochemistry 42, 9619-9625].

Synthesis of morphiceptin (Tyr-Pro-Phe-Pro-NH(2)) by dipeptidyl aminopeptidase IV derived from Aspergillus oryzae.

Morphiceptin (Tyr-Pro-Phe-Pro-NH(2)), tetrapeptide, was synthesized using dipeptidyl aminopeptidase IV (DP IV, EC 3.4.14.5) derived from Aspergillus oryzae RIB 915 as a catalyst. Tyr-Pro-OEt was incubated with Phe-Pro-NH(2) in the presence of DP IV under various conditions of temperature, concentrations of ethylene glycol, pH, reaction time, and others. Morphiceptin was obtained at 40% yield under the optimal reaction conditions: substrate, 4 mM Tyr-Pro-OEt.HCl and 20 mM Phe-Pro-NH(2).HCl; enzyme, DP IV, 0.275 nkat; solvent, 60% ethylene glycol containing 20 mM phosphate buffer at pH 7.0; amine, 4.2 mM diisopropylamine at 4 degrees C for 24 h. Amino group protection was unnecessary for synthesis of morphiceptin by DP IV.