Malignant pleural mesotheliomas is in most cases associated with elevated amounts of hyaluronan. To investigate the importance of hyaluronan for the malignant properties of mesotheliomas, we have expressed murine hyaluronan synthase 2 (HAS2) in the non-hyaluronan producing mesothelioma cell line, Mero-25. We found that upon hyaluronan overproduction the mesothelioma cells changed their epitheloid character to a fibroblastic phenotype and were surrounded by pericellular matrices, the size of which correlated to the amount of synthesized hyaluronan. HAS2-transfected cells with the ability to synthesize about 520 ng hyaluronan/5 × 104cells/24 h exhibited about a 2-fold increase in the expression of the cell surface hyaluronan receptor CD44 and their locomotion increased compared to that of mock-transfected Mero-25 cells. Furthermore, the malignant properties of mesothelioma cell clones as determined by the ability to grow in a soft agar assay correlated to their hyaluronan production. These results provide evidence for an important role of hyaluronan in the aggressive spread of mesotheliomas in adjacent non-cancerous stromal tissues. © 2001 Cancer Research Campaign http://www.bjcancer.com
Background: Intra-uterine growth restriction (IUGR) is an important risk factor for perinatal morbidity and mortality in prematurity. Placental insufficiency leading to chronic fetal hypoxemia is a well known cause for IUGR. Therefore, the aim of the study was to establish a mouse model for the experimental induction of IUGR caused by reduced maternal inspiratory oxygen to obtain a chronic fetal hypoxemia. Besides auxological data for evaluation of growth restriction, pulmonary surfactant protein (SP) mRNA expression was investigated, addressing the potential impact of IUGR on lung development.Methods: Pregnant mice (C57BL/6) were randomized into two groups: dams (nϭ5) of the first group were held under hypoxic conditions (10% O2) starting at day 14 of gestation. The second group of dams (nϭ5; control) remained under normoxic conditions. All animals were fed ad libitum. At day 17.5 of gestation (term 19 -21 days) fetuses of both groups were delivered prematurely by C-section. To estimate the degree of growth restriction the following key characteristics were selected: birthweight, body length (vertex-tail), head length (rostral-occipital). Pulmonary mRNA expression of SP-A, SP-B, SP-C, SP-D was quantified using real time PCR (deltadeltaCT-method; housekeeping gene: beta-actin). Statistical analyses were performed using Mann-Whitney U test.Results: Compared to controls, hypoxic fetuses showed significantly reduced (pϽ0.0001) birthweight (-28.6%); body length (-13.8%) and head length (-7.7%). Furthermore, pulmonary mRNA expression of SP-A, B and C was significantly decreased in fetuses kept under hypoxic conditions in contrast to controls (pϽ0.05). SP-D mRNA expression was not altered.Conclusion: Maternal hypoxia revealed to be adequate for the experimental induction of IUGR. Reduced mRNA expression of SP-A, B and C in growth restricted preterm mice (day 17.5 of gestation) may indicate an impaired lung maturation. Background:Continuous positive airway pressure (CPAP) has become a preferred method of respiratory support to preterm infants, especially those with birth weights Ͻ1250 g. In a study by Sreenan et al, standard nasal cannula with flows up to 2.5 L/min were used in neonates Ͻ2.0 kg. This 'high-flow' system was shown to deliver similar positive distending pressures compared to ventilator-generated nasal CPAP, and was effective in reducing apnea of prematurity. Since that publication, 'high-flow' CPAP has become increasingly popular in our neonatal intensive care. Its use has been felt to minimize nasal irritation from conventional nasal prongs. Our usual method of CPAPdelivery is an infant flow system (IFS). The purpose of this study was to determine whether high-flow CPAP was as effective as IFS CPAP in neonates Ͻ1250 g. HIGH-FLOW NASAL CANNULA CPAP VERSUS INFANT FLOW NASAL CPAP IN NEW-LY-EXTUBATED NEONATES <1250GMethods: Preterm infants Ͻ1250 g were randomized following their first extubation to either high-flow or IFS CPAP. Those randomized to the high-flow had flow determined by the following equation: ...
Purpose Epidemiological data indicate correlation between life long exposure to ultraviolet radiation and cortical cataract. There is no experimental data on the effect of daily repeated in vivo exposures of the eye to UVR. This experiment was designed to verify whether the dose additivity for UVR exposures holds through periods of time up to 30 days. Methods Eighty rats were conditioned to a rat restrainer five days prior to exposure. All animals were divided into 4 exposure period classes of 1, 3, 10 and 30 days of exposure to UVR. Each exposure period class of 20 animals was randomly divided into five cumulated UVR dose sub‐groups. Eighteen‐week‐old non‐anesthetized albino Sprague‐Dawley(SD) rats were exposed daily to UVR‐300 nm for 15 minutes. One week after the last exposure, animals were sacrificed. The lenses were extracted for macroscopic imaging of dark‐field anatomy and degree of cataract was quantified by measurement of intensity of forward lens light scattering. Maximum tolerable dose (MTD2.3:16), statistically defined standard for sensitivity for threshold for UVR cataract, was estimated for the periods of exposure and plotted with a linear regression as a function of days during which dose was accumulated. Results All exposed lenses developed anterior subcapsular cataract with varying appearance depending on the period of days exposed to UVR. Small single doses of UVR accumulated to cause cataract during the periods up to 30 days. MTD2.3:16 for 1, 3, 10 and 30 days of repeated exposures was estimated to 4.7, 4.74, 4.8 and 6.0 kJ/m2, respectively. Conclusion The tolerance to UVR‐B for 18 week old SD rat increases with increasing number of days being exposed. With lower single dose and longer duration for daily exposure the lens is more tolerant to UVR.
Purpose To determine the exposure time dependence of lens light scattering after high power in vivo infrared radiation exposure of the eye. Methods The experimental animal was 6 weeks old albino SD rat. Altogether, 12 animals were divided into four exposure time groups (5, 8, 13, 20 s). The animals were anesthetized with ketamine‐xylazine, 95/14 mg/kg bodyweight, 20 min prior to exposure and both eyes were dilated with tropicamide 10 mg/ml. The infrared radiation source was a single mode CW fiber laser emitting at 1090 nm (Model SP‐120C, SPI Lasers, UK) with the output power set to 6.2 W. The primary laser beam was focused just in front of the anterior focal point of the eye with an F# close to that of the rat eye so that a divergent beam entered the eye with a spot size of 3 mm in diameter inside the dilated pupil. This allowed for a homogenous intensity distribution within the lens and a large spot size on the retina. One week after exposure, the animal was sacrificed and the lenses were extracted for darkfield macroscopic imaging and measurement of intensity of forward light scattering. Results The intensity of forward light scattering increased with increasing exposure time. The increase was well described by a 2nd order polynomial, omitting the 0:th and the first order term. The threshold exposure time, estimated as Maximum Tolerable exposure Time (MTT:2.3:16) was 4.8 s. Considering the power used, this corresponds to 30 J, thus delivered over 3 mm diameter which implies a radiant exposure of 4.2 MJ/m2. Conclusion At 1 week after exposure to 6.2 W of 1090 nm, the intensity of forward light scattering in the lens increases with increasing exposure time and the threshold exposure time is 4.8 s.
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