A modified method of measuring plasma volume with indocyanine green: reducing the frequency of blood sampling while maintaining accuracy.

Among various methods for measuring the plasma volume (PV), the indocyanine green (ICG) dilution technique is a relatively less invasive method. However, the ICG method is rather cumbersome because 10 blood samples need to be obtained within a short time after ICG administration. Thus, reducing the frequency of blood sampling while maintaining the accuracy would facilitate plasma volume measurement in clinical situations. We here developed a modified method to measure plasma volume using 2260 ICG plasma concentration data from 115 surgical patients. The mean relative error (MRE) and the percentage of cases with relative error (RE) greater than 5% in total (PRE) were used to quantify the difference between plasma volumes obtained by the original and modified methods. RE was determined as follows. RE(%) = (PV obtained by original method (PVoriginal)-PV obtained by modified method (PVmodified))/PVoriginal × 100. PVmodified was assumed to be equal to PVoriginal when the RE was < 5%. When the number of samples selected for the plasma volume estimation was 4 or less, the PRE was mostly 10% or more. Five out of the 10 blood samples (order: 1st, 2nd, 3rd, 9th, and 10th) showed similar accuracies with the plasma volume obtained by the original method (original: 2.72 ± 0.64 l, modified: 2.72 ± 0.65 l). This modified method may be able to aptly replace the original method and lead to a wider clinical application of the ICG dilution technique. Further validation is needed to determine if the results of this study may be applied in other populations.

Quantitative analysis of the effect of fraction of inspired oxygen on peripheral oxygen saturation in healthy volunteers.

BACKGROUND: The international organization for standardization (ISO) 80601-2-61 dictates that the accuracy of a pulse oximeter should be assessed by a controlled desaturation study. We aimed to characterize the relationship between the fraction of inspired oxygen (FiO2) and peripheral oxygen saturation (SpO2) using a turnover model by retrospectively analyzing the data obtained from previous controlled desaturation studies. MATERIALS AND METHODS: Each volunteer was placed in a semi-Fowler's position and connected to a breathing circuit to administer the hypoxic gas mixture containing medical air, oxygen, nitrogen, and carbon dioxide. Volunteers were exposed to various levels of induced hypoxia over 70-100% arterial oxygen saturation (SaO2). The study period consisted of two rounds of hypoxia and the volunteers were maintained in room air between each round. FiO2 and SpO2 were recorded continuously during the study period. A population pharmacodynamic analysis was performed with the NONMEM VII level 4 (ICON Development Solutions, Ellicott City, MD, USA). RESULTS: In total, 2899 SpO2 data points obtained from 20 volunteers were used to determine the pharmacodynamic characteristics. The pharmacodynamic parameters were as follows: kout = 0.942 1/min, Imax = 0.802, IC50 = 85.3%, γ = 27.3. CONCLUSION: The changes in SpO2 due to decreases in FiO2 well explained by the turnover model with inhibitory function as a sigmoidal model.

Enzymatic Synthesis of ß-Glucosylglycerol and Its Unnatural Glycosides Via ß-Glycosidase and Amylosucrase.

ß-Glucosylglycerol (ß-GG) and their derivatives have potential applications in food, cosmetics and the healthcare industry, including antitumor medications. In this study, ß-GG and its unnatural glycosides were synthesized through the transglycosylation of two enzymes, Sulfolobus shibatae ß-glycosidase (SSG) and Deinococcus geothermalis amylosucrase (DGAS). SSG catalyzed a transglycosylation reaction with glycerol as an acceptor and cellobiose as a donor to produce 56% of ß-GGs [ß-D-glucopyranosyl-(1→1/3)-D-glycerol and ß-D-glucopyranosyl- (1→2)-D-glycerol]. In the second transglycosylation reaction, ß-D-glucopyranosyl-(1 → 1/3)-Dglycerol was used as acceptor molecules of the DGAS reaction. As a result, 61% of α-Dglucopyranosyl-( 1→4)-ß-D-glucopyranosyl-(1→1/3)-D-glycerol and 28% of α-D-maltopyranosyl- (1→4)-ß-D-glucopyranosyl-(1→1/3)-D-glycerol were synthesized as unnatural glucosylglycerols. In conclusion, the combined enzymatic synthesis of the unnatural glycosides of ß-GG was established. The synthesis of these unnatural glycosides may provide an opportunity to discover new applications in the biotechnological industry.

Usefulness of mindfulness-based cognitive therapy for treating insomnia in patients with anxiety disorders: a pilot study.

The objective of this study was to examine the usefulness of a mindfulness-based cognitive therapy (MBCT) for treating insomnia symptoms in patients with anxiety disorder. Nineteen patients with anxiety disorder were assigned to an 8-week MBCT clinical trial. Participants showed significant improvement in Pittsburgh Sleep Quality Index (Z = -3.46, p = 0.00), Penn State Worry Questionnaire (Z = -3.83, p = 0.00), Ruminative Response Scale (Z = -3.83, p = 0.00), Hamilton Anxiety Rating Scale (Z = -3.73, p = 0.00), and Hamilton Depression Rating Scale scores (Z = -3.06, p = 0.00) at the end of the 8-week program as compared with baseline. Multiple regression analysis showed that baseline Penn State Worry Questionnaire scores were associated with baseline Pittsburgh Sleep Quality Index scores. These findings suggest that MBCT can be effective at relieving insomnia symptoms by reducing worry associated sleep disturbances in patients with anxiety disorder. However, well-designed, randomized, controlled trials are needed to confirm our findings.