SBC2007-175993 MEASUREMENT OF IN-VIVO PULMONARY VASCULAR IMPEDANCE IN TWO ANIMAL MODELS OF PULMONARY HYPERTENSION

INTRODUCTION Pulmonary vascular input impedance has been increasingly promoted as an important diagnostic for pulmonary arterial hypertension (PAH) The human studies noted above have understandably not examined detailed associations between impedance and vascular behavior and structure, since the latter data are obtainable only through focused drug studies or ex-vivo measurements. Mechanical changes to a vascular network should be reflected in its input impedance; thus, such investigation should be useful in determining how impedance varies with changes in vascular condition, such as chronic stiffening due to vascular remodeling or acute stiffening due to smooth muscle cell response and/or pressure-induced strain-stiffening. Naturally, clinical identification of such stiffness changes on a routine basis could greatly impact diagnosis. Here, we demonstrate simple-toimplement impedance measurements in two animal models as part of a larger effort to establish said links between clinically-viable diagnostics, such as impedance, and physiological changes that occur to the vasculature as part of the progression of PAH. METHODS Animal Preparation: The two animal models examined here develop PAH due to chronic exposure to a hypoxic environment. The first model consisted of 10 male Sprague-Dawley rats (300-400g), half exposed to hypoxia via hypobaric chamber for 3-4 weeks (barometric pressure ≈ 410 mmHg) and half retained at standard conditions in Denver, CO (barometric pressure ≈ 630 mmHg). The second model utilized 4 male Holstein calves (70-110lb), again with half exposed to hypoxia for two weeks (barometric pressure ≈ 460 mmHg) and the other half remaining normoxic. Both models were exposed to a 12:12-h light-dark cycle, and water and appropriate food were made available ad libitum. Animal care and use committees at both the University of Colorado Health Science Center (rat) and Colorado State University (calf) approved all protocols and procedures. Animal Data Collection and Analysis: The measurements obtained from each animal are identical; the main differences between collection methods are equipment size and type. For all measurements, rats are anesthetized with ketamine hydrochloride (40 mg/kg) and xylazine (10 mg/kg) intraperitoneally, while cows remain conscious. Right jugular access is then obtained in each animal, and a fluid filled catheter, consisting of PV1 tubing for the rat or a commercial Swan-Ganz catheter for the calf, is inserted into the main pulmonary artery (MPA) for pressure measurements. During collection of MPA pressure, blood velocity at the midline of the MPA is obtained with pulse-wave Doppler echocardiography using an FPA probe on a commercial ultrasound scanner (Vivid 5, GE Medical Systems Inc). The imaging depth dictates the probe frequency

Tear secretion dysfunction among women workers engaged in light-on tests in the TFT-LCD industry

BACKGROUND: The TFT-LCD (thin film transistor liquid crystal display) industry is rapidly growing in Taiwan and many other countries. A large number of workers, mainly women, are employed in the light-on test process to detect the defects of products. At the light-on test workstation, the operator is generally exposed to low humidity (in the clean room environment), flashing light, and low ambient illumination for long working hours. Many workers complained about eye discomfort, and therefore we conducted a study to evaluate the tear secretion function of light-on test workers of a TFT-LCD company. METHODS: We recruited workers engaged in light-on tests in the company during their periodical health examination. In addition to a questionnaire survey of demographic characteristics and ophthalmic symptoms, we evaluated the tear secretion function of both eyes of each participant using the Schirmer's lacrimal basal secretion test with anaesthesia. A participant with one or both eyes yielding abnormal test results was defined as a case of tear secretion dysfunction. RESULTS: During the study period, a total of 371 light-on test workers received the health examination at the clinic of the park, and 52 of them were excluded due to having ophthalmic diseases and other systemic diseases that may affect ophthalmic function. All the remaining 319 qualified workers agreed to participate in this study, and they were all females working by 4-shift rotations. The average age was 24.2 years old (standard deviation [SD] = 3.8), and the average employment duration was 13.6 months (SD = 5.7). Among the 11 ophthalmic symptoms evaluated, eye dryness was the most prevalent (prevalence = 43.3%). In addition, the prevalence of tear secretion dysfunction in at least one eye was 40.1% (128 cases), and contact lens users had an odds ratio of 1.73 (95% confidence interval = 1.02–2.94) in comparison with non-contact lens users. Comparing the Schirmer's test results of those who also participated in the screening in the previous year, we found 40 of the 156 participants (17.2%) with normal test results in the previous year turned abnormal in 2001. In contrast, only 21 of the 76 participants (9.1%) with abnormal test results in the previous year turned normal, and the difference was statistically significant (p = 0.02 for McNemar's test). CONCLUSION: The prevalence of tear secretion dysfunction in woman workers engaged in light-on tests is high and increases with a one-year duration of employment. The use of contact lens may further increase the risk

Acupuncture for dry eye: a randomised controlled trial protocol

<p>Abstract</p> <p>Background</p> <p>Dry eye is usually managed by conventional medical interventions such as artificial tears, anti-inflammatory drugs and surgical treatment. However, since dry eye is one of the most frequent ophthalmologic disorders, safer and more effective methods for its treatment are necessary, especially for vulnerable patients. Acupuncture has been widely used to treat patients with dry eye. Our aim is to evaluate the effectiveness and safety of acupuncture for this condition.</p> <p>Methods/Design</p> <p>A randomised, patient-assessor blinded, sham (non-acupuncture point, shallow acupuncture) controlled study was established. Participants allocated to verum acupuncture and sham acupuncture groups will be treated three times weekly for three weeks for a total of nine sessions per participant. Seventeen points (GV23; bilateral BL2, GB4, TE23, Ex1 (Taiyang), ST1 and GB20; and left SP3, LU9, LU10 and HT8 for men, right for women) have been selected for the verum acupuncture; for the sham acupuncture, points have been selected that do not coincide with a classical acupuncture point and that are located close to the verum points, except in the case of the rim of the eye. Ocular surface disease index, tear film breakup time, the Schirmer I test, medication quantification scale and general assessment of improvement will be used as outcome variables for evaluating the effectiveness of acupuncture. Safety will also be assessed at every visit. Primary and secondary outcomes will be assessed four weeks after screening. All statistical analyses will be performed using analysis of covariance.</p> <p>Discussion</p> <p>The results of this trial will be used as a basis for clarifying the efficacy of acupuncture for dry eye.</p> <p>Trial registration</p> <p>ClinicalTrials.gov NCT00969280.</p

Can air pollution affect tear film stability? a cross-sectional study in the aftermath of an explosion accident

<p>Abstract</p> <p>Background</p> <p>After an explosion and fire in two tanks containing contaminated oil and sulphur products in a Norwegian industrial harbour in 2007, the surrounding area was polluted. This caused an intense smell, lasting until the waste was removed two years later. The present study reports examinations of tear film break up time among the population. The examinations were carried out because many of the people in the area complained of sore eyes. The purpose of the study was to assess the relationship between living or working close to the polluted area and tear film stability one and a half years after the explosion.</p> <p>Methods</p> <p>All persons working or living in an area less than six kilometres from the explosion site were invited to take part in the study together with a similar number of persons matched for age and gender living more than 20 kilometres away. Three groups were established: workers in the explosion area and inhabitants near the explosion area (but not working there) were considered to have been exposed, and inhabitants far away (who did not work in the explosion area) were considered to be unexposed. A total of 734 people were examined, and the response rate was 76 percent. Tear film stability was studied by assessing non-invasive break-up time (NIBUT) using ocular microscopy. In addition Self-reported Break Up Time (SBUT) was assessed by recording the time the subject could keep his or hers eyes open without blinking when watching a fixed point on a wall. Background information was obtained using a questionnaire. Non-parametric Wilcoxon-Mann-Whitney-tests with exact p-values and multiple logistic regression analyses were performed.</p> <p>Results</p> <p>Both NIBUT and SBUT were shorter among the male exposed workers than among the inhabitants both near and far away from the explosion area. This was also found for SBUT among males in a multiple logistic regression analysis, adjusting for age and smoking.</p> <p>Conclusions</p> <p>Reduced tear film stability was found among workers in an area where an explosion accident had occurred.</p

Synthesis of a square-planar rhodium alkylidene N-heterocyclic carbene complex and its reactivity toward alkenes

The first rhodium alkylidene square-planar complex stabilized by an N-heterocyclic carbene ligand, RhCl(-CHPh)(IPr)PPh3 (2; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-carbene), has been prepared by reaction of RhCl(IPr)(PPh3)2 (1) with phenyldiazomethane and its dynamic behavior in solution studied. Treatment of 2 with alkenes results in the formation of the ¿2-olefin complexes RhCl(¿2-CH2-CHR)(IPr)PPh3 (3, R = H; 4, R = Ph; 5, R = OEt) and new olefins arising from the coupling of the alkylidene with the alkenes, likely via a metallacyclobutane intermediate