Investigations Directed Toward the Synthesis of New Cyclopentanoids Using Optically Active Bicyclo[2.2.1]heptene Monoester

The synthetic utilization of a chiral building block obtained by the enzymatic asymmetric hydrolysis of a symmetric diester having the bicyclo[2.2.1]heptene system was investigated. Several cyclopentanoids have been synthesized in high yields in enatiomerically enriched forms with the use of simple reactions. These compounds are expected to serve as useful chiral synthons for cyclopentane-containing natural products and pharmaceuticals

Non-invasive calibration method for pulse oximeters

In case of a healthy subject the normal SpO2 value is 97 ± 2% on see level. Modern, finger probe based pulse oximeters are measuring the SpO2 level with 1-2% error. The dispersion between subjects can reach 4%, thus such accuracy is not really demanded by the majority of clinicians. Moreover, in case of fetal pulse oximetry 5% measuring error is accepted. Considering these factors we investigated the feasibility of a non-invasive calibration method with a self-developed pulse oximeter. This method is carried out without blood sampling. Pulse oximeters are measuring the R rate, which is proportional to the SpO2 value. Calibrating an oximeter means finding the function between the R and SpO2. A calibrated pulse oximeter was used as reference. In the case of every subject 15 minutes long measurements were performed. The reference device and our oximeter were attached to the subject at the same time, while artificial air with 14% oxygen content was inhaled by the subject for ten minutes. The SpO2 was measured by the reference oximeter and the R rate by our oximeter. Based on 511 measured data pairs the relationship was determined between 86-100%. The relationship was estimated by linear regression. Although the original relation is non-linear, linear estimation can be used in this small range of SpO2 with good accuracy. The average error of the calibrated device is 2.76%, which is appropriate in medical practice. This method is easier and cheaper as the invasive calibration, but the calibrated device will have slightly bigger measuring error

Phantom with Pulsatile Arteries to Investigate the Influence of Blood Vessel Depth on Pulse Oximeter Signal Strength

This paper describes a three-layer head phantom with artificial pulsating arteries at five different depths (1.2 mm, 3.7 mm, 6.8 mm, 9.6 mm and 11.8 mm). The structure enables formation of spatially and temporally varying tissue properties similar to those of living tissues. In our experiment, pressure pulses were generated in the arteries by an electronically controlled pump. The physical and optical parameters of the layers and the liquid in the artificial arteries were similar to those of real tissues and blood. The amplitude of the pulsating component of the light returning from the phantom tissues was measured at each artery depth mentioned above. The build-up of the in-house-developed pulse oximeter used for performing the measurements and the physical layout of the measuring head are described. The radiant flux generated by the LED on the measuring head was measured to be 1.8 mW at 910 nm. The backscattered radiant flux was measured, and found to be 0.46 nW (0.26 ppm), 0.55 nW (0.31 ppm), and 0.18 nW (0.10 ppm) for the 1.2 mm, 3.7 mm and 6.8 mm arteries, respectively. In the case of the 9.6 mm and 11.8 mm arteries, useful measurement data were not obtained owing to weak signals. We simulated the phantom with the arteries at the above-mentioned five depths and at two additional ones (2.5 mm and 5.3 mm in depth) using the Monte Carlo method. The measurement results were verified by the simulation results. We concluded that in case of 11 mm source-detector separation the arteries at a depth of about 2.5 mm generate the strongest pulse oximeter signal level in a tissue system comprising three layers of thicknesses: 1.5 mm (skin), 5.0 mm (skull), and >50 mm (brain)

Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes

Surgical Correction of Cor Triatriatum Associated with Pulmonary Artery Thrombosis in an Adult

We herein present a case of a successful correction of cor triatriatum associated with thrombotic pulmonary hypertension diagnosed in an adult female patient. We confirmed diagnosis using transthoracic and transesophageal echocardiography in addition to cardiac computed tomography and magnetic resonance imaging. Surgical repair comprised excision of the fibromuscular membranous septum in the left atrium, patch closure of an atrial septal defect, and reconstruction of the pulmonary arteries with a vascular graft. Cor triatriatum complicated pulmonary thrombotic hypertension with atrial septal defect is amenable to surgical correction with satisfactory results