113 research outputs found
Cetuximab-Ag₂S quantum dots for fluorescence imaging and highly effective combination of ALA-based photodynamic/chemo-therapy of colorectal cancer cells
Colorectal cancer (CRC) has a poor prognosis and urgently needs better therapeutic approaches. 5-Aminolevulinic acid (ALA) induced protoprophyrin IX (PpIX) based photodynamic therapy (PDT) is already approved in the clinic for several cancers but not yet well investigated for CRC. Currently, systemic administration of ALA offers a limited degree of tumour selectivity, except for intracranial tumours, limiting its wider use in the clinic. Combination of effective ALA-PDT with chemotherapy may provide a promising alternative approach for CRC treatment. Herein, theranostic Ag2S quantum dots (AS-2MPA) optically trackable in near-infrared (NIR), conjugated with endothelial growth factor receptor (EGFR) targeting Cetuximab (Cet) and loaded with ALA for PDT monotherapy or ALA/5-fluorouracil (5FU) for the combination therapy is proposed for enhanced treatment of EGFR(+) CRC. AS-2MPA-Cet endowed excellent targeting of the high EGFR expressing cells and showed a strong intracellular signal for NIR optical detection in a comparative study performed on SW480, HCT116, and HT29 cells, which are high, medium and low EGFR expressers. Targeting provided enhanced uptake of the ALA loaded nanoparticles by strong EGFR expressing cells and formation of higher levels of PpIX. Cells also differ in their efficiency to convert ALA to PpIX, and SW480 was the best, followed by HT29, while HCT116 were determined as unsuitable for ALA-PDT. The therapeutic efficacy was evaluated in 2D cell cultures and 3D spheroids of SW480 and HT29 cells using AS-2MPA with either electrostatically loaded, hydrazone or amide linked ALA to achieve different levels of pH or enzyme sensitive release. Most effective phototoxicity was observed in SW480 cells using AS-2MPA-ALA-electrostatic-Cet due enhanced uptake of the particles, fast ALA release and effective ALA-to-PpIX conversion. Targeted delivery reduced the effective ALA concentration significantly which was further reduced with codelivery of 5FU. Delivery of ALA via covalent linkage was also effective for PDT, but required longer incubation time for the release of ALA in therapeutic doses. Phototoxicity was correlated with high levels of reactive oxygen species (ROS) and apoptotic/necrotic cell death. Hence, both AS-2MPA-ALA-Cet based PDT and AS-2MPA-ALA-Cet-5FU based Chemo/PDT combination therapy coupled with strong NIR tracking of the nanoparticles demonstrate an exceptional therapeutic effect on CRC cells and an excellent potential for synergistic multistage tumour targeting therapy
Blue laser cooling transitions in Tm I
We have studied possible candidates for laser cooling transitions in
Tm in the spectral region 410 -- 420 nm. By means of saturation
absorption spectroscopy we have measured the hyperfine structure and rates of
two nearly closed cycling transitions from the ground state
to upper states
at
410.6 nm and
at
420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and
48(6) ns respectively. Decay rates from these levels to neighboring
opposite-parity levels are evaluated by means of Hartree-Fock calculations. We
conclude, that the strong transition at 410.6 nm has an optical leak rate of
less then and can be used for efficient laser cooling of
Tm from a thermal atomic beam. The hyperfine structure of two other
even-parity levels which can be excited from the ground state at 409.5 nm and
418.9 nm is also measured by the same technique. In addition we give a
calculated value of s for the rate of magnetic-dipole transition
at 1.14 m between the fine structure levels
of the ground state which can be
considered as a candidate for applications in atomic clocks.Comment: 8 pages, 5 figure
Pediatric cochlear implantation: an update
Deafness in pediatric age can adversely impact language acquisition as well as educational and social-emotional
development. Once diagnosed, hearing loss should be rehabilitated early; the goal is to provide the child with
maximum access to the acoustic features of speech within a listening range that is safe and comfortable. In presence
of severe to profound deafness, benefit from auditory amplification cannot be enough to allow a proper language
development. Cochlear implants are partially implantable electronic devices designed to provide profoundly deafened
patients with hearing sensitivity within the speech range. Since their introduction more than 30 years ago, cochlear
implants have improved their performance to the extent that are now considered to be standard of care in the
treatment of children with severe to profound deafness. Over the years patient candidacy has been expanded and
the criteria for implantation continue to evolve within the paediatric population. The minimum age for implantation
has progressively reduced; it has been recognized that implantation at a very early age (12–18 months) provides
children with the best outcomes, taking advantage of sensitive periods of auditory development. Bilateral implantation
offers a better sound localization, as well as a superior ability to understand speech in noisy environments than unilateral
cochlear implant. Deafened children with special clinical situations, including inner ear malformation, cochlear nerve
deficiency, cochlear ossification, and additional disabilities can be successfully treated, even thogh they require
an individualized candidacy evaluation and a complex post-implantation rehabilitation. Benefits from cochlear
implantation include not only better abilities to hear and to develop speech and language skills, but also improved
academic attainment, improved quality of life, and better employment status. Cochlear implants permit deaf people
to hear, but they have a long way to go before their performance being comparable to that of the intact human ear;
researchers are looking for more sophisticated speech processing strategies as well as a more efficient coupling
between the electrodes and the cochlear nerve with the goal of dramatically improving the quality of sound of
the next generation of implants
CHD7 Mutational Analysis and Clinical Considerations for Auditory Rehabilitation in Deaf Patients with CHARGE Syndrome
BACKGROUND: Otologic manifestations are one of the most consistent findings of CHARGE syndrome found in more than 90%. Since genetic analysis of the CHD7 gene has rarely been performed in previous reports dealing with ear abnormalities, the genotypic spectrum of CHD7 mutations was analyzed in deaf patients with CHARGE syndrome, and the clinical considerations concerning auditory rehabilitation were investigated. METHODS: Nine Korean patients with CHARGE syndrome showing profound hearing loss and semicircular canal aplasia were included. All 38 exons of CHD7 were analyzed by direct sequencing. For splice site variations, in silico and exon-trapping analyses were performed to verify the pathogenicity of nucleotide variations. Clinical features and the outcome of auditory rehabilitation were also analyzed. RESULTS: Eight of 9 patients revealed alterations of the CHD7 gene including 3 frameshift, 2 nonsense, 2 splice site, and 1 missense mutations. Five of 9 patients were clinically diagnosed as atypical CHARGE syndrome but demonstrated various mutations of the CHD7 gene. One familial case showed intra-familial variability. Radiologic findings suggesting cochleovestibular nerve deficiency were identified in most of the patients. Of the 8 patients who underwent cochlear implantation, 5 patients demonstrated favorable outcome. Larger diameter of the cochleovestibular nerve on imaging and absence of severe mental retardation were factors related to better outcome after cochlear implantation rather than the type of CHD7 mutations. Auditory brainstem implantation was performed in two patients who did not benefit from cochlear implantation. CONCLUSIONS: Genetic analysis of the CHD7 gene should be performed in cases with semicircular canal aplasia even when other typical features of CHARGE syndrome are absent. For auditory rehabilitation in CHARGE syndrome, cochlear implantation should be strongly recommended in selected cases with favorable prognostic factors. Auditory brainstem implantation may be a viable option in patients with CHARGE syndrome who have failed to benefit from cochlear implantation
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