Assessment of carboxyhemoglobin content in the blood with high accuracy: wavelength range optimization for nonlinear curve fitting of optical spectra

Highly efficient continuous-wave solid-state Raman crystal lasers at 555 and 559 nm

High-power efficient continuous-wave Nd:YVO4/KGW Raman lasers at 555 and 559 nm are achieved by using a double-sided dichroic coating output coupler to improve the resonance quality factor. The Np-cut potassium gadolinium tungstate (KGW) is used to generate the Stokes waves at 1159 and 1177 nm by placing the polarization of the1064 nm fundamental wave parallel to the Ng and Nm axes, respectively. The lithium triborate (LBO) crystal with the cut angle in the XY plane for the type-I phase matching is used to perform the intracavity sum frequency generation for yielding the green light at 555 nm and the lime light at 559 nm at the optimal phase matching temperature. Experimental results were systematically accomplished to comprehend the optimal cavity length for the conversion efficiency. Under the optimal cavity length, the output powers can reach 6.6 and 6.3 W at a pump power of 22 W for the wavelengths of 555 and 559 nm, respectively. The conversion efficiencies can be up to 30% and 28.6% for 555 and 559 nm, respectively.

Modeling Gasotransmitter Availability to Brain Capillary Endothelial Cells with Ultrasound-sensitive Microbubbles

BACKGROUND

Vascular cognitive impairment and dementia results from blood components passing through disrupted blood brain barriers (BBBs). Current treatments can reduce further progress of neuronal damage but do not treat the primary cause. Instead, these treatments typically aim to temporarily disrupt the BBB. Alternatively, this study computationally assessed the feasibility of delivering carbon monoxide (CO) from ultrasound-sensitive microbubbles (MBs) as a strategy to promote BBB repair and integrity. CO can interact with heme-containing compounds within cells and promote cell growth. However, careful dose control is critical for safety and efficacy because CO also binds at high affinity to hemoglobin (Hb).

METHODS

Ultrasound activation was simulated at the internal carotid artery, and CO released from the resulting MB rupture was tracked along the shortest path to the BBB for several activation times and doses. The CO dose available to brain capillary endothelial cells (BCECs) was predicted by considering hemodynamics, mass transport, and binding kinetics.

RESULTS

The half-life of CO binding to Hb indicated that CO is available to interact with BCECs for several cardiac cycles. Further, MB and COHb concentrations would not be near toxic levels and free Hb would be available. The axisymmetric model indicated that biologically-relevant CO concentrations will be available to BCECs, and these levels can be sustained with controlled ultrasound activation. A patient-specific geometry shows that while vessel tortuosity provides a heterogeneous response, a relevant CO concentration could still be achieved.

CONCLUSIONS

This computational study demonstrates feasibility of the CO / MB strategy, and that controlled delivery is important for viability of this strategy.

Atomic Force Microscopy and High-Resolution Spectrophotometry for Study of Anoxemia and Normoxemia in Model Experiment In Vitro

The oxygen content in the blood may decrease under the influence of various physicochemical factors and different diseases. The state of hypoxemia is especially dangerous for critically ill patients. In this paper, we describe and analyze the changes in the characteristics of red blood cells (RBCs) with decreasing levels of oxygen in the RBC suspension from normoxemia to hypoxemia/anoxemia in an in vitro model experiment. The RBCs were stored in hypoxemia/anoxemia and normoxemia conditions in closed and open tubes correspondingly. For the quantitative study of RBC parameter changes, we used atomic force microscopy, digital spectrophotometry, and nonlinear curve fitting of the optical spectra. In both closed and open tubes, at the end of the storage period by day 29, only 2% of discocytes remained, and mainly irreversible types, such as microspherocytes and ghosts, were observed. RBC hemolysis occurred at a level of 25-30%. Addition of the storage solution, depending on the concentration, changed the influence of hypoxemia on RBCs. The reversibility of the change in hemoglobin derivatives was checked. Based on the experimental data and model approach, we assume that there is an optimal level of hypoxemia at which the imbalance between the oxidative and antioxidant systems, the rate of formation of reactive oxygen species, and, accordingly, the disturbances in RBCs, will be minimal.

Preclinical study for the ameliorating effect of l-ascorbic acid for the oxidative stress of chronic administration of organic nitrates on myocardial tissue in high sucrose/fat rat model

Background

The therapeutic activity of Glyceryl trinitrate (GTN) is mainly regulated by liberating nitric oxide (NO) and reactive nitrogen species (RNS). During this biotransformation, oxidative stress and lipid peroxidation inside the red blood cells (RBCs) occur. Hemoglobin tightly binds to NO forming methemoglobin altering the erythrocytic antioxidant defense system.

Aim

The principal objective of our research is to show the ameliorating effect of l-ascorbic acid for the deleterious effects of chronic administration of nitrovasodilator drugs used in cardiovascular diseases such as oxidative stresses and tolerance.

Method

We studied some biochemical parameters for the oxidative stress using groups of high sucrose/fat (HSF) diet Wistar male rats chronically orally administered different concentrations of Isosorbide-5-mononitrate (ISMN) 0.3 mg/kg, 0.6 mg/kg and 1.2 mg/kg. Afterwards, we evaluated the role of l-ascorbic acid against these biochemical changes in cardiac tissues.

Results

Chronic treatment with organic nitrates caused elevated serum levels of lipid peroxidation, hemoglobin derivatives as methemoglobin and carboxyhemoglobin, rate of hemoglobin autoxidation, the cellular levels of the pro-inflammatory cytokines marker (NF-κB) and apoptosis markers (caspase-3) in the myocardium muscles in a dose-dependent manner. Meanwhile, such exposure caused a decline in the enzymatic effect of SOD, GSH and CAT accompanied by a decrease in the level of mitochondrial oxidative stress marker (nrf2) in the myocardium muscles and a decrease in the serum iron and total iron-binding capacity (TIBC) in a dose-dependent manner. Concomitant treatment with l-ascorbic acid significantly diminished these changes for all examined parameters.

Conclusion

Chronic administration of organic nitrates leads to the alteration of the level of oxidative stress factors in the myocardium tissue due to the generation of reactive oxygen species. Using l-ascorbic acid can effectively ameliorate such intoxication to overcome nitrate tolerance.

The Toxic Influence of Excess Free Iron on Red Blood Cells in the Biophysical Experiment: An In Vitro Study

Iron is needed for life-essential processes, but free iron overload causes dangerous clinical consequences. The study of the role of red blood cells (RBCs) in the influence of excess free iron in the blood on the pathological consequences in an organism is relevant. Here, in a direct biophysical experiment in vitro, we studied the action of free iron overload on the packed red blood cell (pRBC) characteristics. In experiments, we incubated pRBCs with the ferrous sulfate solution (Fe²⁺). Wе used free iron in a wide range of concentrations. High Fe²⁺ concentrations made us possible to establish the pattern of the toxic effect of excess iron on pRBCs during a reduced incubation time in a biophysical experiment in vitro. It was found that excess free iron causes changes in pRBC morphology, the appearance of bridges between cells, and the formation of clots, increasing the membrane stiffness and methemoglobin concentration. We created a kinetic model of changes in the hemoglobin derivatives. The complex of simultaneous distortions of pRBCs established in our experiments can be taken into account when studying the mechanism of the toxic influence of excess free iron in the blood on pathological changes in an organism.