Gain saturation in a semiconductor optical amplifier with an array of quantum dots is studied analytically and by numerical simulation on the basis of an analysis of rate equations. It is shown that, ...at a moderate injection level, the saturation power increases in proportion to the current density, and then reaches its maximum value, limited by the rate of carrier delivery to the ground state and by the number of quantum dots interacting with photons. Expressions are proposed that allow explicit description of the dependence of the saturation power on current and its relationship with the internal parameters of the active region.
We studied cytotoxic activity of new tetranitrosyl NO-generating binuclear iron—sulfur Fe—S complexes containing different ligands in the molecule against tumor cells
in vitro
. Cytotoxic activity of ...the most active complex with cysteamine (CysAm) was compared with that of antitumor drug cisplatin. Caspase activation and morphological changes in cells were visualized by fluorescence microscopy. Fluorescence of active caspases 3 and 7 and changes in nuclear DNA in cells in the presence of CyAm were detected by using fluorochrome-labeled inhibitor of caspases (FLICA) and Hoechst and propidium iodide reagents. Similar cytotoxic activities of CyAm and cisplatin were demonstrated in various human tumor cell lines of different histogenesis. Therefore, a new class of NO-donating Fe—S complexes can provide the base of potential drugs for chemotherapy with a new mechanism of action.
The dependence of the spectral position of the lasing line of a microdisk laser with InAs/InGaAs/GaAs quantum dots on the refractive index of an aqueous solution in which the microlaser is immersed ...is studied. A maximum resonance shift of 9.4 nm/RIU was obtained for 10-μm-diameter microlasers immersed in an aqueous glucose solution.
Theoretically, we calculated exciton fraction in polariton modes, which correlates with the intensity of the exciton radiation associated with these modes for several microcavities. Thus, we obtained ...the form of the dependence of the radiation probability on the eigenfrequencies of the structure.
It was proposed that increased level of mitochondrial reactive oxygen species (ROS), mediating execution of the aging program of an organism, could also be critical for neoplastic transformation and ...tumorigenesis. This proposal was addressed using new mitochondria-targeted antioxidant SkQ1 (10-(6'-plastoquinonyl) decyltriphenylphosphonium) that scavenges ROS in mitochondria at nanomolar concentrations. We found that diet supplementation with SkQ1 (5 nmol/kg per day) suppressed spontaneous development of tumors (predominantly lymphomas) in p53⁻/⁻ mice. The same dose of SkQ1 inhibited the growth of human colon carcinoma HCT116/p53⁻/⁻ xenografts in athymic mice. Growth of tumor xenografts of human HPV-16-associated cervical carcinoma SiHa was affected by SkQ1 only slightly, but survival of tumor-bearing animals was increased. It was also shown that SkQ1 inhibited the tumor cell proliferation, which was demonstrated for HCT116 p53⁻/⁻ and SiHa cells in culture. Moreover, SkQ1 induced differentiation of various tumor cells in vitro. Coordinated SkQ1-initiated changes in cell shape, cytoskeleton organization, and E-cadherin-positive intercellular contacts were observed in epithelial tumor cells. In Ras- and SV40-transformed fibroblasts, SkQ1 was found to initiate reversal of morphological transformation of a malignant type, restoring actin stress fibers and focal adhesion contacts. SkQ1 suppressed angiogenesis in Matrigel implants, indicating that mitochondrial ROS could be important for tumor angiogenesis. This effect, however, was less pronounced in HCT116/p53⁻/⁻ tumor xenografts. We have also shown that SkQ1 and related positively charged antioxidants are substrates of the P-glycoprotein multidrug resistance pump. The lower anti-tumor effect and decreased intracellular accumulation of SkQ1, found in the case of HCT116 xenografts bearing mutant forms of p53, could be related to a higher level of P-glycoprotein. The effects of traditional antioxidant N-acetyl-L-cysteine (NAC) on tumor growth and tumor cell phenotype were similar to the effects of SkQ1 but more than 1,000,000 times higher doses of NAC than those of SkQ1 were required. Extremely high efficiency of SkQ1, related to its accumulation in the mitochondrial membrane, indicates that mitochondrial ROS production is critical for tumorigenesis at least in some animal models.
The single mode lasing of microdisks (MDs) with attached antibodies in aqueous medium is demonstrated. MDs comprise quantum dot active region emitting in the vicinity of 1.3 μm. The presence of ...antibodies on a MD surface leads to a number of effects, including the increase of threshold power of laser generation, likewise, changes in the linewidth of the resonance peak.
Lasing of optically pumped semiconductor microdisks immersed in aqueous medium is demonstrated for the first time. Microlasers containing quantum dot active region were placed into the transparent ...polydimethylsiloxane chamber filled with distilled water at room temperature. The spectral and threshold characteristics of the lasers are compared in both air and aqueous environments. We suppose that such high-Q microlasers can be used as highly sensitive biosensors.
It is demonstrated that microdisk lasers about 10 μm in diameter with an active region based on InAs/InGaAs quantum dots synthesized on GaAs substrates can be used for biodetection. Chimeric ...monoclonal antibodies against the CD20 protein that are covalently attached to the surface of microdisk lasers operating in an aqueous medium under optical pumping and room temperature were used as detectable objects. It is shown that the addition of secondary antibodies leads to an increase in the threshold power of laser generation, as well as to an increase in the full width at half maximum (FWHM) of the resonance laser line.
Quantum-dot microdisk lasers coated with different dielectric layers transparent in spectral diapason of laser radiation were studied. We observe that the coating influences the mode spectra of the ...microlasers, reduces the resonator Q factor and improves their thermal resistance.
Technologies for Prediction of Preeclampsia Rokоtyanskаya, E A; Panova, I A; Malyshkina, A I ...
Sovremennye tekhnologii v medit͡s︡ine,
01/2020, Letnik:
12, Številka:
5
Journal Article
Recenzirano
Odprti dostop
was to develop technologies for predicting the development of preeclampsia (PE) based on biomedical and molecular-genetic predictors and the calculation of individual risks for this pregnancy ...complication.
The study involved 457 pregnant women. Of them, 147 women had chronic arterial hypertension (CAH); 109 pregnant women had CAH and secondary preeclampsia (PE); 201 patients had PE. The control group consisted of 105 pregnant women without hypertensive disorders or proteinuria. We performed a retrospective analysis of gestation course and labor outcomes, calculated risk factors using the Open Epi system and logistic regression method. Polymorphisms of genes controlling the vascular tone were identified in venous blood.
There were identified risk factors for developing PE, including those in women with CAH: chronic pyelonephritis; baseline mean AP above 95 mm Hg and diastolic AP above 80 mm Hg; body mass index over 30; family history of arterial hypertension. The following were identified as additional predictors of PE: perinatal loss; premature labor; spontaneous miscarriage; PE and closed craniocerebral injuries in the past medical history; threatening miscarriage in the first trimester. Additional risk factors for PE in women with CAH were found: lack of regular antihypertensive therapy before pregnancy and in the first trimester; chronic gastritis; first pregnancy; tobacco smoking.Polymorphic variants of the
(-786)C allele in the genotype in combination with the heterozygous genotype in the
1675G/A gene are associated with a high risk of CAH. The presence of alleles
(-786)T/C and
(-786)C, as well as a combination of alleles
(-786)C and
894G/T, is associated with PE. The presence of alleles
704C,
(-344)T, and
825T/T in the genotype, both individually and in combination, is a risk factor for the development of PE secondary to CAH. The data obtained made it possible to develop a method for predicting the onset of PE in women with CAH and a model for calculating the individual risk of PE, which formed the basis for a computer program.
Calculating the individual risks of PE using the technologies proposed by the authors allows identifying pregnant women belonging to the high-risk group on a timely basis, which ensures high-quality implementation of preventive measures, provides a personalized approach and the possibility to prove the need for additional examination of this category of patients.
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