Glycogen ß-particles surface characterized by a combination of size exclusion chromatography and pyrene excimer fluorescence before and after ß-amylolysis.

Size exclusion chromatography (SEC) and pyrene excimer formation (PEF) experiments were conducted to characterize the local density profile inside a glycogen sample before (Glycogen) and after (Gly-ß-LD) treatment with ß-amylase. These experiments were conducted to assess whether the density at the periphery of the glycogen particles was very high to limit access to proteins involved in the metabolism of glycogen as predicted by the Tier model or low as suggested by the Gilbert model. SEC analysis indicated that the density inside the Glycogen and Gly-ß-LD samples remained constant with particle size and was not affected by ß-amylolysis. Analysis of the PEF experiments conducted on the Glycogen and Gly-ß-LD samples labeled with 1-pyrenebutyric acid showed that the particles have a dense interior and loose corona. The conclusions reached by the SEC and PEF experiments agree with the Gilbert model and have implications for the association of glycogen ß-particles into larger α-particles.

Interior of glycogen probed by pyrene excimer fluorescence.

A glycogen sample from oyster (O) and another from corn (C) were fluorescently labeled with 1-pyrenebutyric acid to yield two series of pyrene-labeled glycogen samples (Py-Glycogen(O/C)). Analysis of the time-resolved fluorescence (TRF) measurements of the Py-Glycogen(O/C) dispersions in dimethyl sulfoxide yielded the maximum number () of anhydroglucose units (AGUs), that could separate two pyrene-labeled AGUs and still allow efficient pyrene excimer formation (PEF) between an excited and a ground-state pyrene. Molecular mechanics optimizations (MMOs) were conducted on a lattice of hexagonally close packed oligosaccharide helices to determine how the theoretical Nblobtheo varied as a function of the lattice density. Comparing and , obtained after integrating Nblobtheo along the local density profile ρ(r) across the glycogen particles, led to the conclusion that ρ(r) took a maximum value at the center of the glycogen particles contrary to expectations based on the Tier Model.

Cluster Size of Amylopectin and Nanosized Amylopectin Fragments Characterized by Pyrene Excimer Formation.

Amylopectin from waxy corn and the three nanosized amylopectin fragments (NAFs)-NAF(56), NAF(20), and NAF(8)-from waxy corn starch with a hydrodynamic diameter of 227, 56, 20, and 8 nm, respectively, were randomly labeled with 1-pyrenebutyric acid. The efficiency of these pyrene-labeled amylopectin-based polysaccharides (Py-AbPS) for pyrene excimer formation (PEF) upon diffusive encounter between an excited and a ground-state pyrene increased with increasing concentration of unlabeled NAF(56) in Py-AbPS dispersions in DMSO. Fluorescence decay analysis of the Py-AbPS dispersions in DMSO prepared with increasing [NAF(56)] yielded the maximum number (Nblobexp) of anhydroglucose units (AGUs) separating two pyrene-labeled AGUs while still allowing PEF. Comparison of Nblobexp with Nblobtheo, obtained by conducting molecular mechanics optimizations on helical oligosaccharide constructs with HyperChem, led to a relationship between the interhelical distance (dh-h) in a cluster of oligosaccharide helices, [NAF(56)], and the number of helices in a cluster. It was found that the AbPSs were composed of building blocks made of 3.5 (±0.9) helices that self-assembled into increasingly larger clusters with increasing [NAF(56)]. The ability of PEF-based experiments to yield the cluster size of AbPSs provides a new experimental means to probe the interior of AbPSs at the molecular level.

Spatial and Temporal Bioactive Compound Contents and Chlorophyll Fluorescence of Kale (Brassica oleracea L.) Under UV-B Exposure Near Harvest Time in Controlled Environments.

UV-B irradiation has been used to enhance the secondary metabolite content in plants, but its spatial effect on plants has not been considered. The objective of this study was to compare spatial photosynthetic traits and bioactive compound accumulation in kale (Brassica oleracea L. var Acephala) according to the distribution and length of UV-B exposure near harvest. Plants were exposed to UV-B of 0-3, 3-6 and 6-9 W m-2 for 4 h per day at 5 days (Exp. 1) and 4.2 W m-2 at 5, 4, 3, 2 or 1 days (Exp. 2) before harvest. In spatial distribution, the higher the UV-B intensity, the lower the mean Fv /Fm (maximal photochemical efficiency of PSII) and the higher the concentration of total flavonoid compound (TFC). With UV-B stress, Fv /Fm and fluorescence transient parameters decreased except for DI0 /CS (dissipated energy flux per cross section) and PIabs (performance index of PSII). When exposed to UV-B radiation for 2 days before harvest, the total phenolic compounds and TFC per plant were highest, not always proportional to the local Fv /Fm but affected by dry weight. Short-term UV-B stress near harvest would be more efficient for the accumulation of bioactive compounds by minimizing the loss of plant weight.

Surfactant Structure-Dependent Interactions with Modified Starch Nanoparticles Probed by Fluorescence Spectroscopy.

The interactions between the surfactants sodium dodecyl sulfate (SDS) and sodium dioctyl sulfosuccinate (AOT) and starch nanoparticles (SNPs) hydrophobically modified with the hydrophobic dye pyrene (Py-SNPs) were investigated in water by steady-state and time-resolved fluorescence. The Py-SNPs formed interparticulate aggregates in water, which were disrupted by adding SDS to the Py-SNP aqueous dispersions. SDS was found to interact with Py-SNPs at SDS concentrations that were close to 2 orders of magnitude lower than its critical micelle concentration (CMC). These interactions led to the breakup of the Py-SNP aggregates, which was confirmed by conducting fluorescence resonance energy transfer experiments between naphthalene-labeled SNPs (Np-SNPs) and Py-SNPs. By the time the SDS concentration reached the CMC of SDS, the Py-SNPs were separated from each other and excimer was generated from isolated Py-SNPs in the aqueous dispersions. Whereas SDS interacted with the Py-SNPs at SDS concentrations lower than CMC, SDS did not seem to target the hydrophobic pyrene aggregates. Only above the CMC did SDS appear to interact with the pyrene aggregates, as evidenced from diffusive pyrene excimer formation between excited and ground-state pyrenes. Most surprisingly, no interaction was observed between sodium dioctyl sulfosuccinate (AOT) and Py-SNP at AOT concentrations where SDS interacted with the Py-SNPs. This observation led to the conclusion that SDS below its CMC interacted not with hydrophobic pyrene aggregates but rather through the formation of inclusion complexes, which led to the electrostatic stabilization of individual Py-SNPs and enabled the breakup of Py-SNP aggregates. The formation of inclusion complexes with linear surfactants like SDS might thus provide a new means of stabilizing hydrophobically modified starch nanoparticles in water, which bears the promise of finding future applications.

Applications of Pyrene Fluorescence to the Characterization of Hydrophobically Modified Starch Nanoparticles.

Several aspects of pyrene fluorescence were applied to gain an insight into the nature of the microdomains in hydrophobically modified starch nanoparticles (HM-SNPs), prepared by reacting SNPs with propionic and hexanoic anhydride to yield C3- and C6-SNPs, respectively. The fluorescence experiments took advantage of the inherent hydrophobicity of pyrene to bind onto the hydrophobic domains generated by the HM-SNPs, and its specific response to the polarity of its environment, to probe its accessibility to quenchers such as oxygen or nitromethane dissolved in water. The equilibrium constant KB for the binding of pyrene onto HM-SNPs, the ratio ( I1/ I3)o describing the relative hydrophobicity of the microenvironment experienced by pyrene, its lifetime (τSNP), and the rate constant of quenching of pyrene bound to the HM-SNPs by water-soluble nitromethane ( kqSNP) were determined as a function of the degree of substitution and weight fraction (wt %) of the hydrophobic modifier. The C3- and C6-SNPs yielded similar parameters at low levels of hydrophobic modification, indicating higher hydrophobicity of the modified SNPs with increasing modification level. However, SNPs modified with more than 5 wt % of hexanoyl pendants all displayed enhanced hydrophobicity for the C6-SNPs relative to the C3-SNPs. This substantial enhancement is attributed to the formation of larger hydrophobic microdomains by the hexanoyl pendants of the C6-SNPs above the 5 wt % C6-modification threshold, which did not occur with the C3-SNPs. Finally, the size of the SNPs did not appear to influence their relative hydrophobicity. These experiments demonstrate how the fluorescence of pyrene can be harnessed to provide information about the relative hydrophobicity of HM-SNPs.

Clinical significance of serum CA-125 in Korean females with ascites.

PURPOSE: Mycobacterium tuberculosis is endemic in Korea. Because tuberculous peritonitis is characterized by ascites, abdominal pain, abdominal mass and elevation of serum CA-125, it can be confused with ovarian malignancies. The aim of this study was to evaluate the significance of serum CA-125 level in the differential diagnosis of tuberculous peritonitis and ovarian malignancy in a Mycobacterium tuberculosis-endemic area. MATERIALS AND METHODS: The medical records of patients diagnosed with tuberculous peritonitis (n=48) or epithelial ovarian malignancy (n=370) at Samsung Medical Center from January 2000 to October 2009 were retrospectively reviewed. RESULTS: Median serum CA-125 level in the epithelial ovarian cancer group was significantly higher than that in the tuberculous peritonitis group (p ≤ 0.01). Only one patient (2.1%) in the tuberculous peritonitis group had a serum CA-125 level over 2000 U/mL. However, 109 patients (29.5%) in the epithelial ovarian cancer group had a serum CA-125 level over 2000 U/mL. At the CA-125 ranges of 400 to 599 and 600 to 799, the proportions of those with tuberculous peritonitis were 24% and 21.9%, respectively. At a serum CA-125 level over 1000 U/mL, however, the proportion of tuberculous peritonitis was much lower (2.1%). CONCLUSION: Tuberculous peritonitis should be considered in the evaluation of female patients with ascites and high serum CA-125.

Esophageal parakeratosis mimicking endoscopic appearance of superficial esophageal neoplastic lesion such as dysplasia.

The endoscopic findings of esophageal parakeratosis have not been well defined and its clinical significance including malignant potential is unclear. Here, we report a case of esophageal parakeratosis presenting as a discrete flat elevated lesion and mimicking the endoscopic appearance of superficial esophageal neoplastic lesion such as dysplasia or cancer. A 72-year-old woman was referred to our hospital for an esophageal lesion detected by upper endoscopy during a medical check-up. Upper endoscopy revealed a 5-cm sized whitish flat elevated lesion involving the mucosa of the middle esophagus. The surface of this lesion showed mild nodularity and the margin was discrete. When spraying with lugol solution, the lesion was not stained. On microscopic examination, esophageal parakeratosis was noted on the luminal surface with a hyaline eosinophilic cytoplasm and small elongate nuclei oriented parallel to the surface. Although pathological examination of initial biopsy specimens revealed no evidence of neoplasia or infection, we carried out follow-up upper endoscopies 1 month and 1 year later because of endoscopic findings mimicking dysplasia or cancer. Endoscopic and histopathological findings from the first and the second follow-up upper endoscopies were same as those of the first examination and the final diagnosis of esophageal parakeratosis was made. Given the present case, esophageal parakeratosis needs to be considered as a differential diagnosis when a flat elevated lesion is found in the esophagus and biopsy specimens reveal no evidence of dysplasia or cancer.

[A case of cap polyposis complicated with idiopathic retroperitoneal fibrosis].

An optimal treatment for cap polyposis has not been established. Several treatment approaches, including anti-inflammatory agents, antibiotics, immunomodulators, and endoscopic therapy have been described. Surgical resection of the affected colon and rectum may be indicated for patients with persistent disease. Repeat surgery is indicated in cases of recurrence after surgery. However, symptomatic polyposis may still recur, and spontaneous resolution of cap polyposis is possible. We report a case of recurrent cap polyposis complicated with retroperitoneal fibrosis after inadequate low anterior resection with a positive resection margin. Surgical approaches for the treatment of cap polyposis should be carefully considered before treatment.