Effects of protein coding polymorphisms in the kallikrein 1 gene on baseline blood pressure and antihypertensive response to irbesartan in Chinese hypertensive patients

The aim of this study was to determine the association between coding variants in the human tissue kallikrein 1 (KLK1) gene and baseline blood pressure (BP) and antihypertensive response to irbesartan treatment in Chinese hypertensive patients. A total of 1061 hypertensives were recruited and received daily oral dosage of 150 mg irbesartan for 4 weeks. Predose BPs, BPs and blood irbesartan concentrations at postdose on the 28th day were all measured. Common functional single-nucleotide polymorphisms (SNPs) in the KLK1 gene were genotyped. On the basis of the HapMap data of Han Chinese in the Beijing population, two non-synonymous polymorphisms with minor allele frequency>0.1, SNP rs5517 (Glu162Lys) and rs5516 (Gln121Glu), were selected. Those with GG genotype in the rs5516 locus had higher average baseline systolic BP (SBP) than CC subjects (β±s.e.: 5.0±2.3, P=0.033); and no associations of rs5517 with baseline BP (diastolic BP (DBP) and SBP) and BP responses, or rs5516 with baseline DBP and BP response were observed. In a haplotype-based association test for the KLK1 gene, the Haplo-special score analyses identified that haplotype AG was marginally associated with SBP response (specific score: 1.75 for P=0.08), but not with DBP response. We did not find any associations between haplotypes (GC and AC) and BP responses. The Haplo-GLM analyses showed that, compared with haplotype GC subjects, the subjects with haplotype AG had a marginally greater SBP response (adjusted β±s.e.: 1.81±0.97, P=0.06), but DBP response did not differ. This study suggests that rs5516 in the KLK1 gene may be involved in the development of essential hypertension and in the regulation of SBP-lowering response to irbesartan in Chinese hypertensives.

Compact all-fiber optical Faraday components using 65-wt%-terbium-doped fiber with a record Verdet constant of -32 rad/(Tm)

A compact all-fiber Faraday isolator and a Faraday mirror are demonstrated. At the core of each of these components is an all-fiber Faraday rotator made of a 4-cm-long, 65-wt%-terbium-doped silicate fiber. The effective Verdet constant of the terbium-doped fiber is measured to be -32 rad/(Tm), which is 27 x larger than that of silica fiber. This effective Verdet constant is the largest value measured to date in any fiber and is 83% of the Verdet constant of commercially available crystal used in bulk optics-based isolators. Combining the all-fiber Faraday rotator with fiber polarizers results in a fully fusion spliced all-fiber isolator whose isolation is measured to be 19 dB. Combining the all-fiber Faraday rotator with a fiber Bragg grating results in an all-fiber Faraday mirror that rotates the polarization state of the reflected light by 88 +/- 4 degrees .

Monitoring of hemodynamic changes induced in the healthy breast through inspired gas stimuli with MR-guided diffuse optical imaging

PURPOSE

The modulation of tissue hemodynamics has important clinical value in medicine for both tumor diagnosis and therapy. As an oncological tool, increasing tissue oxygenation via modulation of inspired gas has been proposed as a method to improve cancer therapy and determine radiation sensitivity. As a radiological tool, inducing changes in tissue total hemoglobin may provide a means to detect and characterize malignant tumors by providing information about tissue vascular function. The ability to change and measure tissue hemoglobin and oxygenation concentrations in the healthy breast during administration of three different types of modulated gas stimuli (oxygen/ carbogen, air/carbogen, and air/oxygen) was investigated.

METHODS

Subjects breathed combinations of gases which were modulated in time. MR-guided diffuse optical tomography measured total hemoglobin and oxygen saturation in the breast every 30 s during the 16 min breathing stimulus. Metrics of maximum correlation and phase lag were calculated by cross correlating the measured hemodynamics with the stimulus. These results were compared to an air/air control to determine the hemodynamic changes compared to the baseline physiology.

RESULTS

This study demonstrated that a gas stimulus consisting of alternating oxygen/carbogen induced the largest and most robust hemodynamic response in healthy breast parenchyma relative to the changes that occurred during the breathing of room air. This stimulus caused increases in total hemoglobin and oxygen saturation during the carbogen phase of gas inhalation, and decreases during the oxygen phase. These findings are consistent with the theory that oxygen acts as a vasoconstrictor, while carbogen acts as a vasodilator. However, difficulties in inducing a consistent change in tissue hemoglobin and oxygenation were observed because of variability in intersubject physiology, especially during the air/oxygen or air/carbogen modulated breathing protocols.

CONCLUSIONS

MR-guided diffuse optical imaging is a unique tool that can measure tissue hemodynamics in the breast during modulated breathing. This technique may have utility in determining the therapeutic potential of pretreatment tissue oxygenation or in investigating vascular function. Future gas modulation studies in the breast should use a combination of oxygen and carbogen as the functional stimulus. Additionally, control measures of subject physiology during air breathing are critical for robust measurements.