Thermostable β-Lactamase Mutant with Its Active Site Conjugated with Fluorescein for Efficient β-Lactam Antibiotic Detection

Monitoring the β-lactam antibiotic level has been an important task in food industry and clinical practice. Here, we report the development of a fluorescent PenP β-lactamase, PenP-E166Cf/N170Q, for efficient β-lactam antibiotic detection. It was constructed by covalently attaching fluorescein onto the active-site entrance of a thermostable E166Cf/N170Q mutant of a Bacillus licheniformis PenP β-lactamase. It gave a fluorescence turn-on signal toward various β-lactam antibiotics, where the fluorescence enhancement was attributed to the acyl-enzyme complex formed between PenP-E166Cf/N170Q and the β-lactam antibiotic.
It demonstrated enhanced signal stability over its parental PenP-E166Cf because of the suppressed hydrolytic activity by the N170Q mutation. Compared with our previously constructed PenPC-E166Cf biosensor, PenP-E166Cf/N170Q was more thermostable and advanced in detecting β-lactams in terms of response time, signal stability, and detection limit. Positive fluorescence signals generated by E166Cf/N170Q in response to the penicillin-containing milk and mouse serum illustrated the feasibility of the biosensor for antibiotic detection in real samples. Taken together, our findings suggest the potential application of PenP-E166Cf/N170Q in biosensing β-lactam antibiotics.

Fluorescein Angiographic Findings in Patients with Active Systemic Lupus Erythematosus.

To evaluate the retina of patients with active systemic lupus erythematosus (SLE) using fundus fluorescein angiography (FFA), irrespective of their visual acuity or fundus examination.
METHODS
A descriptive study was performed on 30 patients with active SLE; disease activity was calculated using The Systemic Lupus Erythematosus Disease Activity Index (SLEDAI). Fundus examination and FFA angiography were done to all patients.
RESULTS
A total of 60 eyes of 30 patients were included. Their mean age was 32.6 ± 1.17 years. All patients showed disease activity at time of examination according to SLEDAI. Retinopathy was detected by FAF in 24 eyes (40%), 10 eyes of which had normal fundus examination. SLEDAI was positively correlated to the presence of retinopathy.
CONCLUSIONS
All patients with ocular lupus should be carefully evaluated for systemic involvement and, vice versa, all patients diagnosed with SLE should have a thorough ocular examination and FFA, even if they had normal fundus.

Biotinylated Cubosomes: A Versatile Tool for Active Targeting and Codelivery of Paclitaxel and a Fluorescein-Based Lipid Dye.

The functionalization of cubosomes with biotin is reported here as an alternative method for the preparation of drug delivery systems capable of active targeting specific receptors that are (over)expressed by cancer cells. We describe the design, synthesis, assembly, and characterization of these novel cubosome nanoparticles by small-angle X-ray scattering (SAXS) and dynamic laser light scattering (DLS) and show their application to human adenocarcinoma cell line HeLa.
These cubosomes are stabilized and functionalized with a novel, designed biotin-based block copolymer and are able to simultaneously transport paclitaxel, a potent anticancer drug, and a hydrophobic fluorescent dye in the active targeting of cancer cells. Such biotinylated cubosomes are potentially applicable in diagnosis, drug delivery, and monitoring of the therapeutic response for active targeting versus cancer cells.

Applicability of the fluorescein diacetate method of detecting active bacteria in freshwater.

  • Fluorescein diacetate (FDA) hydrolysis was evaluated as a means to detect actively metabolizing bacteria in freshwater. Fluorescein diacetate, a nonfluorescent derivative of fluorescein, can be transported across cell membranes and deacetylated by nonspecific esterases. Resultant fluorescein accumulates within cells and allows direct visualization by epifluorescent microscopy. Application of FDA to a variety of freshwater habitats yielded estimates of active cells ranging from 6-24% of the total population.
  • These estimates were 49-61% lower than estimates of active cells obtained from measures of electron transport activity. The difference was attributed to low permeability of the fluorogen through the outer membrane of heterotrophic gram-negative cells. Data suggest that FDA hydrolysis as a means of detecting active bacteria may be limited to environments rich in eucaryotes and gram-positive cells.

[Study on the mechanism of energy transfer between fluorescein sodium and tetrabromofluorescein sodium in micelles of cationic surface active agent].

In the present paper, the fluorescence reaction of cationic surface-active agents (CSAA) with Tetrabromofluorescein sodium (TBF) in aqueous solution was investigated. It was found that the fluorescence quenching of TBF appears when it reacts with the cation monomer of a CSAA and a new stronger fluorescence is obtained when the ion-associates react with the micellate of CSAA. The authors investigated the condition of energy transfer between acidic fluorescent dyes in micelles of cetyl trimethyl ammonium bromide or hexadecyl pyridinium bromide.
It was indicated that in the micelles formed by cationic surface active agent with dyes embedded (cationic surface active agent and dyes are charge opposite), the effective energy transfer between anionic dyes could occur. When the concentration of cationic surface active agent reached certain value, the energy transfer could occur. With the value of two thirds of critical micelle concentration, the efficiency of energy transfer reached the maximum; when the concentration of cationic surface active agent increased, the efficiency of energy transfer would be decreased. The authors also deduced the model of energy transfer between dyes in micelles and laws of it.

Fluorescein angiography and visual acuity in active uveitis with Behçet disease.

To determine the association of fluorescein angiography characteristics with visual acuity and visual loss during medical treatment in patients with Behçet uveitis.
METHODS
Ninety-three eyes from 69 Behçet patients with active panuveitis underwent fluorescein angiography, and the characteristic findings by angiography were determined. The patients were followed with immunomodulatory treatment.
RESULTS
Diffuse vascular leakage (73.4%), diffuse macular leakage (66.0%), and disc leakage (52.7%) were the predominant angiographic findings on fluorescein angiography. Multivariate logistic regression analysis revealed that a macular window defect and disc neovascularization on fluorescein angiography were associated with poor visual acuity (<or= 20/200) (p < .05). The presence of macular ischemia on fluorescein angiography was significantly associated with the risk of visual loss (<or= 20/200) at 48 months post-treatment (p < .05).
CONCLUSIONS
These results suggest that fluorescein angiography may be helpful for predicting visual prognosis for Behçet patients with panuveitis.

Fluorescein Active Caspase Staining Kit

K2047-25 ApexBio 25 assays 238 EUR

Fluorescein Active Caspase-12 Staining Kit

K2046-25 ApexBio 25 assays 238 EUR

Fluorescein Active Caspase-2 Staining Kit

K2048-25 ApexBio 25 assays 238 EUR

Fluorescein Active Caspase-3 Staining Kit

K2049-25 ApexBio 25 assays 238 EUR

Fluorescein Active Caspase-8 Staining Kit

K2050-25 ApexBio 25 assays 238 EUR

Fluorescein Active Caspase-9 Staining Kit

K2051-100 ApexBio 100 assays 572 EUR

Fluorescein Active Caspase-9 Staining Kit

K2051-25 ApexBio 25 assays 238 EUR

CaspGLOW? Fluorescein Active Caspase Staining Kit

K180-100 Biovision 550 EUR

CaspGLOW? Fluorescein Active Caspase Staining Kit

K180-25 Biovision 234 EUR

CaspGLOW? Fluorescein Active Caspase-12 Staining Kit

K172-100 Biovision 523 EUR

CaspGLOW? Fluorescein Active Caspase-12 Staining Kit

K172-25 Biovision 234 EUR

CaspGLOW? Fluorescein Active Caspase-2 Staining Kit

K182-100 Biovision 523 EUR

CaspGLOW? Fluorescein Active Caspase-2 Staining Kit

K182-25 Biovision 234 EUR

CaspGLOW? Fluorescein Active Caspase-3 Staining Kit

K183-100 Biovision 550 EUR

CaspGLOW? Fluorescein Active Caspase-3 Staining Kit

K183-25 Biovision 234 EUR

CaspGLOW? Fluorescein Active Caspase-8 Staining Kit

K188-100 Biovision 550 EUR

CaspGLOW? Fluorescein Active Caspase-8 Staining Kit

K188-25 Biovision 240 EUR

CaspGLOW? Fluorescein Active Caspase-9 Staining Kit

K189-100 Biovision 550 EUR

CaspGLOW? Fluorescein Active Caspase-9 Staining Kit

K189-25 Biovision 240 EUR

Fluorescein

HY-D0251 MedChemExpress 1g 139 EUR

Fluorescein DHPE

23304 AAT Bioquest 5 mg 132 EUR

Fluorescein diacetate

FB0202 Bio Basic 5g 158.75 EUR

Fluorescein Diacetate

HY-D0719 MedChemExpress 5g 119 EUR

Fluorescein Biotin

HY-D1030 MedChemExpress 1mg 201 EUR

Fluorescein Phalloidin

HY-K0902 MedChemExpress 300T 843 EUR

Fluorescein diacetate

GT5229-100G Glentham Life Sciences 100 g 524 EUR

Adenosine agonist regulation of outward active transport of fluorescein across retinal pigment epithelium in rabbits.

To investigate the effect of an adenosine agonist, 2-5′-N-ethylcarboxamidoadenosine (NECA), on the outward active transport of fluorescein across the retinal pigment epithelium (RPE) in rabbits. High (5×10(-4)-2×10(-3) M) and low (1×10(-5)-1×10(-4) M) concentrations of NECA or phosphate buffered saline (PBS) were intravitreously injected into Dutch-belted rabbits. Sodium fluorescein was injected intravenously 180 min after NECA. Differential vitreous fluorophotometry was performed 3 hr after the sodium fluorescein injection and the vitreal fluorescein/fluorescein monoglucuronide (F/FG) ratio then was calculated. The F/FG ratios are inversely proportional to the outward active transport of fluorescein across the RPE. Retinal detachments were induced by injection of PBS into the subretinal space after the intravitreous injection of low- or high-dose NECA or PBS, and the size of the blebs was monitored.
In eyes that received a low-dose injection of NECA, the F/FG ratio was higher compared with controls (P<0.05); in eyes that received a high-dose intravitreal injection, the F/FG ratio was significantly lower compared with controls (P<0.05). The effect of low-dose NECA on the F/FG ratio was suppressed by the A2 receptor antagonist, ZM241385, and the effect of high-dose NECA was suppressed by the A1 receptor antagonist, 8-cyclopentyl-1, 3-dipropylxanthine. The A3 receptor antagonist MRS1191 did not influence the effect of low- or high-dose NECA. Intravitreal injection of high-dose NECA enhanced the reabsorption of subretinal fluid compared with PBS; however, low-dose NECA inhibited reabsorption of subretinal fluid (P<0.02 and 0.05, respectively). Intravitreous injection of high-dose NECA accelerates the active outward transport across the RPE via A1 receptors and low-dose NECA decelerates it via A2 receptors.

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