Rapid determination of carbapenem resistance by low-cost colorimetric methods: Propidium Iodide and alamar blue staining.

Carbapenems are a class of ß-lactam antibiotics with a broad antimicrobial activity spectrum. Owing to their sturdy structures resistant to most ß-lactamases, they have been regarded as one of the last-resort antibiotics for combating multidrugresistant bacterial infections. However, the emergence of carbapenem resistance increases predominantly in nosocomial pathogens. To prevent spread of carbapenem resistance in early stages, it is imperative to develop rapid diagnostic tests that will substantially reduce the time and cost in determining carbapenem resistance. Thus, we devised a staining-based diagnostic method applicable to three different Gram-negative pathogens of Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae, all with the high potential to develop carbapenem resistance. Regardless of the resistance mechanisms presented by bacterial species and strains, double staining with propidium iodide (PI) and alamar blue (AB) identified resistant bacteria with an average sensitivity of 95.35%, 7 h after imipenem treatments in 343 clinical isolates. Among the three species tested, A. baumannii showed the highest diagnostic sensitivity of 98.46%. The PI and ABmediated staining method could be a promising diagnostic method with high-throughput efficacy and low cost.

In vitro assessment of selected Korean plants for antioxidant and antiacetylcholinesterase activities.

CONTEXT: Antiacetylcholinesterase (AChE) drugs have been a main therapeutic treatment for Alzheimer's disease because increased AChE levels play a key role in reducing neurotransmission. OBJECTIVES: Extracts from 35 Korean plants were selected and screened for antioxidant and anti-cholinesterase activity to explore new sources derived from Korean natural resources that could be used as AD therapeutic agents. MATERIALS AND METHODS: The antioxidant effect of extracts from 35 selected Korean plants was determined using two most common free radical scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS). Additionally, the effect of extracts, identified as antioxidants, on acetylcholinesterase inhibition was assessed by an acetylcholinesterase assay kit. RESULTS: Out of 36 extracts of 35 plants tested, Oenothera biennis L. (9.09 µg/mL), Saururus chinensis (Lour.) Baill. (9.52 µg/mL) and Betula platyphylla var. japonica (9.85 µg/mL) showed strong DPPH scavenging activity. Twelve other extracts also exerted moderate free radical scavenging activities with IC50 values ranging from 10 to 50 µg/mL. Antioxidant capacity detected by ABTS assay was only significant in O. biennis (23.40 µg/mL), while the other extracts were weak or unable to reduce the production of ABTS. Based on the antioxidant activities of these plant extracts, 19 extracts with IC50 values less than 100 µg/mL in DPPH assay were selected for further AChE inhibition assay. Among the extracts tested, the IC50 value for Prunella vulgaris var. lilacina NAKAI (18.83 µg/mL) in AChE inhibitory activity was the lowest, followed by O. biennis (20.09 µg/mL) and Pharbitis nil Chosy (22.79 µg/mL). CONCLUSIONS: Considering complex multifactorial etiology of AD, the extracts of P. vulgaris var. lilacina (aerial part), O. biennis (seed) and P. nil (seed) may be safe and ideal candidates for future AD modifying therapies.

Assessment of the Tear Meniscus Using Optical Coherence Tomography in Patients With Type 2 Diabetes Mellitus.

PURPOSE: To analyze tear meniscus dimensions with Fourier domain-optical coherence tomography (FD-OCT) in patients with type 2 diabetes mellitus. METHODS: Patients with type 2 diabetes without diabetic retinopathy (DR) (n = 54), with nonproliferative DR (n = 45), with proliferative DR (PDR) (n = 25), and controls (n = 45) were enrolled. Hemoglobin A1c and Early Treatment Diabetic Retinopathy Study (ETDRS) stages of DR were evaluated. Schirmer test (ST), tear breakup time test, and fluorescein corneal staining were carried out. Tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA) were obtained by FD-OCT. RESULTS: TMH, TMD, and TMA in the diabetes and control groups were 233 ± 79 µm, 148 ± 53 µm, and 0.026 ± 0.015 mm, and 261 ± 67 µm, 167 ± 49 µm, and 0.032 ± 0.017 mm, respectively. All parameters were lower in diabetes (all P < 0.01). And the values in PDR were 185 ± 90 µm, 117 ± 50 µm, and 0.017 ± 0.010 mm which were lower than those in control and nonproliferative DR (227 ± 71 µm, 144 ± 50 µm, and 0.023 ± 0.010 mm) (all P < 0.01). TMH, TMD, and TMA correlated with ST (P < 0.01, P = 0.02, and P < 0.01, respectively) and the corneal staining score (all P < 0.01). Patients with longer diabetes duration and a history of panretinal photocoagulation showed significantly decreased TMH, TMD, and TMA (P < 0.01). CONCLUSIONS: OCT, along with tear breakup time and ST, is an effective way to assess tear function in type 2 diabetes. Patients with PDR and a history of panretinal photocoagulation showed lower tear meniscus parameters. The decrease in tear meniscus parameters was correlated with diabetes duration.