| 1. |
- Makdoumi, Karim, 1977-, et al.
(author)
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Different photodynamic effects of blue light with and without riboflavin on methicillin-resistant Staphylococcus aureus (MRSA) and human keratinocytes in vitro
- 2019
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In: Lasers in Medical Science. - : Springer. - 0268-8921 .- 1435-604X. ; 34:9, s. 1799-1805
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Journal article (peer-reviewed)abstract
- Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of infections in humans. Photodynamic therapy using blue light (450 nm) could possibly be used to reduce MRSA on different human tissue surfaces without killing the human cells. It could be less harmful than 300–400 nm light or common disinfectants. We applied blue light ± riboflavin (RF) to MRSA and keratinocytes, in an in vitro liquid layer model, and compared the effect to elimination using common disinfection fluids. MRSA dilutions (8 × 105/mL) in wells were exposed to blue light (450 nm) ± RF at four separate doses (15, 30, 56, and 84 J/cm2). Treated samples were cultivated on blood agar plates and the colony forming units (CFU) determined. Adherent human cells were cultivated (1 × 104/mL) and treated in the same way. The cell activity was then measured by Cell Titer Blue assay after 24- and 48-h growth. The tested disinfectants were chlorhexidine and hydrogen peroxide. Blue light alone (84 J/cm2) eliminated 70% of MRSA. This dose and riboflavin eradicated 99–100% of MRSA. Keratinocytes were not affected by blue light alone at any dose. A dose of 30 J/cm2 in riboflavin solution inactivated keratinocytes completely. Disinfectants inactivated all cells. Blue light alone at 450 nm can eliminate MRSA without inactivation of human keratinocytes. Hence, a high dose of blue light could perhaps be used to treat bacterial infections without loss of human skin cells. Photodynamic therapy using riboflavin and blue light should be explored further as it may perhaps be possible to exploit in treatment of skin diseases associated with keratinocyte hyperproliferation.
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| 2. |
- Makdoumi, Karim, 1977-, et al.
(author)
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Levels of beta-trace protein in optic disc pit with macular detachment
- 2017
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In: Acta Ophthalmologica. - : Wiley-Blackwell Publishing Inc.. - 1755-375X .- 1755-3768. ; 95:8, s. 815-819
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Journal article (peer-reviewed)abstract
- BACKGROUND: To report beta-trace protein (βTP) levels in the subretinal fluid (SRF) of four patients with a macular detachment associated with optic disc pit (ODP).METHODS: Four patients with a serous retinal detachment involving the macula was operated by pars plana vitrectomy (PPV) with C2 F6 gas tamponade and peeling of internal limiting membrane (ILM). Patients with a follow-up period exceeding one year postoperatively were included in the study. The SRF was drained using a fine cannula without laser photocoagulation, and the samples were analysed using particle-enhancing nephelometry. The levels of βTP were compared to 20 routine cerebrospinal fluid (CSF) samples.RESULTS: In four of the five samples from SRF had relatively low βTP levels, with a mean concentration of 6.6 mg/l (range 2.0 to 23.1 mg/l) compared to 16.0 mg/l (range 6.3-26.8 mg/l) in CSF. The only SRF sample within the range corresponding to normal CSF was the first sample from patient 4, and the analysis of the renewed aspirate during the second operation was 2.8 mg/l. Postoperatively, the regression of SRF was slow, but regression of SRF in the foveal region took place in all cases; however, visual acuity (VA) was improved in only half of the patients.CONCLUSION: The results from the analysed SRF regarding βTP concentration in these patients indicate that the SRF in ODP is not identical to CSF, as the concentrations of βTP differ.
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| 3. |
- Makdoumi, Karim, 1977-, et al.
(author)
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Photochemical eradication of methicillin-resistant Staphylococcus aureus by blue light activation of riboflavin
- 2017
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In: Acta Ophthalmologica. - Hoboken, USA : Wiley-Blackwell Publishing Inc.. - 1755-375X .- 1755-3768. ; 95:5, s. 498-502
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Journal article (peer-reviewed)abstract
- Purpose: To compare elimination of methicillin-resistant Staphylococcus aureus (MRSA) by exposure of blue light alone and with riboflavin.Methods: A reference strain of MRSA was cultured and diluted in PBS with and without riboflavin (0.01%). Fifteen microlitre was added on a microscope slide, creating a fluid layer with a thickness of around 400 microns. Both of the bacterial suspensions were exposed to blue light, and the effect between exposure with and without riboflavin was compared. Evaluation involved two different wavelengths (412 and 450 nm) of blue light with a lower (5.4 J/cm(2) ) and higher dose (approximately 28.5 J/cm(2) ). The effect of 412 nm light was also evaluated for a thicker fluid layer (1.17 mm). After exposure, colony-forming units (CFUs) were determined for each solution. All measurements were repeated eight times.Results: The reductions in bacteria were similar for both wavelengths. With riboflavin, a statistically significant elimination was observed for both 412 and 450 nm (p < 0.001). At both dosages, the mean reduction was more pronounced with the presence of riboflavin than without it. Using the higher dose, CFU reduction was 99% and 98%, respectively, for 412 and 450 nm light. The bactericidal efficacy was high also in the deeper fluid layer (93%, higher dose).Conclusion: Riboflavin enhanced the antibacterial effect on the exposed MRSA strain of blue light for both 412 and 450 nm blue light. This indicates that blue light could be considered for possible implementation in deep corneal infections.
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| 4. |
- Makdoumi, Karim, 1977-, et al.
(author)
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Photodynamic UVA-riboflavin bacterial elimination in antibiotic-resistant bacteria
- 2016
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In: Clinical and Experimental Ophthalmology. - : Wiley-Blackwell. - 1442-6404 .- 1442-9071. ; 44:7, s. 582-586
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Journal article (peer-reviewed)abstract
- Background: To evaluate the bactericidal effect of clinical ultraviolet A (UVA) settings used in photoactivated chromophore for infectious keratitis (PACK)-collagen cross-linking (CXL) in antibiotic-resistant and non-resistant bacterial strains.Methods: Well-characterized bacterial strains from clinical isolates, without and with antibiotic resistance, were studied in a pairwise comparison. The evaluated pathogens were Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis. Bacteria were dispersed in PBS and diluted to a concentration of approximately 4x10(5)/ml. Riboflavin was added to a concentration of 0.01%. By spreading the solution on a microscope slide, a fluid film layer, with a thickness of around 400mm, was formed and UVA exposure followed. Eight separate exposures were made for each strain (n=8). The degree of elimination in resistant and non-resistant pathogens was compared.Results: The bactericidal efficacy of exposure differed between the tested microorganisms, and the mean elimination ranged between 60 and 92%, being most extensive in both of the evaluated Pseudomonas strains and least in the E. faecalis strains. Similar reductions were seen in antibiotic-resistant and non-resistant strains, with the exception of S. aureus, in which the resistant strain metchicillin-resistant Staphylococcus aureus (MRSA) was eradicated in a greater extent than the non-resistant strain (P=0.030).Conclusion: UVA-riboflavin settings used in PACK-CXL are effective in reducing both antibiotic-resistant and non-resistant bacteria. Antibiotic resistance does not appear to be protective against the photooxidative exposure.
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| 5. |
- Mäkeläinen, Suvi, et al.
(author)
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An ABCA4 loss-of-function mutation causes a canine form of Stargardt disease
- 2019
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In: PLOS Genetics. - : Public Library of Science. - 1553-7390 .- 1553-7404. ; 15:3
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Journal article (peer-reviewed)abstract
- Autosomal recessive retinal degenerative diseases cause visual impairment and blindness in both humans and dogs. Currently, no standard treatment is available, but pioneering gene therapy-based canine models have been instrumental for clinical trials in humans. To study a novel form of retinal degeneration in Labrador retriever dogs with clinical signs indicating cone and rod degeneration, we used whole-genome sequencing of an affected sib-pair and their unaffected parents. A frameshift insertion in the ATP binding cassette subfamily A member 4 (ABCA4) gene (c.4176insC), leading to a premature stop codon in exon 28 (p.F1393Lfs*1395), was identified. In contrast to unaffected dogs, no full-length ABCA4 protein was detected in the retina of an affected dog. The ABCA4 gene encodes a membrane transporter protein localized in the outer segments of rod and cone photoreceptors. In humans, the ABCA4 gene is associated with Stargardt disease (STGD), an autosomal recessive retinal degeneration leading to central visual impairment. A hallmark of STGD is the accumulation of lipofuscin deposits in the retinal pigment epithelium (RPE). The discovery of a canine homozygous ABCA4 loss-of-function mutation may advance the development of dog as a large animal model for human STGD.
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