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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study describes the effects of CO2 laser radiation on the histology of the normal rabbit arterial wall, using models that simulate laser angioplasty and anastomosis. Rabbit arteries were exposed to laser treatments similar to those used clinically; 40, 0.5 sec pulses of 40-60 mW, CO2 continuous wavelength laser, or a 1/2-circumferential laser anastomosis with a 60-80 mW continuous pulse. Aneurysms developed in 8 of 22 femoral, 1 of 22 carotid, and no controls at 12 week. There were small breaks in the internal elastic lamina with atrophy, loss of muscularis, "packing" of the elastica, thinning of the muscularis at the damage site, and enlargement of the arterial diameter. Aneurysms developed in one femoral and no carotid anastomosed artery. Laser anastomoses demonstrated more muscle damage and loss, with extensive scarring and a wider area of elastic loss than the controls. The intima was reestablished with focal reduplication of the internal elastic lamina. There were no histologic differences between the arteries which developed aneurysms and those which did not in either series. These results suggest that low power laser damage of the arterial wall consists mainly of destruction of the muscularis propria, with minimal damage to the elastica.
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PMID:CO2-laser radiation damage of the arterial wall. 197 23

Continuous wave (CW) CO2 laser using a power of 20 W and a spot size of 0.2 mm was used to cut the left uterine horn in 15 rats. Pulsed CO2 laser using a power of 14 W, pulse repetition rate of 400 pps, and a spot size of 0.2 mm was used to cut the left uterine horn in 16 rats. The right uterine horn was sham-operated and used as a control in each group. Microsurgical anastomosis of the cut horn was performed. The effect on fertility showed a pregnancy rate of 66.6% and 81.25% for the CW and pulsed CO2 laser, respectively. Histopathology studies of the anastomotic site revealed thinning of muscularis with fibrosis of both muscularis and subserosal layers in the CW CO2 laser-treated group. There was no thinning, disruption, or fibrosis of muscularis in pulsed laser-treated group. Adhesion score was not different in the two groups.
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PMID:Comparative study of continuous and pulsed CO2 laser on tissue healing and fertility outcome in tubal anastomosis. 310 8

The surface pH of rat distal colonic mucosa and human rectal mucosa was measured in vitro using first a small pH electrode with a flattened tip. In buffer with pH 7.56 the mean rat colonic surface pH was 6.72. Lowering the buffer pH in steps resulted in a small fall in surface pH, the values being buffer pH 7.06 surface pH 6.64, buffer pH 6.58 surface pH 6.61 and finally buffer pH 6.09 surface pH 6.39. Similar results were obtained with a buffer where butyrate, 30 mmol/l replaced chloride and when a CO2/bicarbonate buffer was used. During the time taken for the study transmural potential difference only changed by 1-2 mV. Serosal surface pH changed with buffer pH, suggesting that the maintained surface pH is a property of the mucosal surface only. The surface pH of human rectal mucosa was similar to that of rat distal colonic mucosa. As buffer pH fell from pH 7.51 to 5.96 mucosal surface pH only fell from pH 6.80 to 6.26. The values obtained in ulcerative proctitis did not differ from normal mucosa. Secondly pH microelectrodes were used to measure the juxta mucosal pH and the pH-microclimate thickness when luminal pH was controlled. The microclimate had a pH 6.63 adjacent to the mucosa with a thickness of 840 micron. The importance of mucus in maintaining the microclimate was shown by n-acetyl cysteine thinning and prostaglandin E2 thickening the layer. These results describe a surface microclimate in the large intestine of appreciable thickness and a constant juxta mucosal pH. Luminal pH changes produce only a small change in microclimate pH.
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PMID:Mucosal surface pH of the large intestine of the rat and of normal and inflamed large intestine in man. 362 17

Specular microscopy was used to measure thickness changes of stroma-endothelium preparations from rabbit corneas in vitro. The preparations were first bathed on both sides for 90 min with different bicarbonate-Ringer solutions (2 to 50 mM bicarbonate) maintained in equilibrium with 5% CO2-air (pH 6.2 to 7.9). During this equilibration, the stroma attained a stable thickness that was inversely related to the hydrostatic pressure (20 to 100 cm H2O) applied to the endothelial surface. After equilibration and at 20 cm H2O pressure, covering the anterior stromal surface with silicone oil (Dow Corning 200 dielectric fluid, 20 cs viscosity) resulted in stromal thinning. The rate of this deturgescence increased (from 5 to 75 micron/h) as the equilibration solution bicarbonate level increased from 2 to 30 mM. The net size of the thickness change was also related to the equilibration bicarbonate level. However, indirect studies on the cornea using phenol red indicator and pH electrode measurements of solutions revealed that the stromal bathing solutions became more alkaline under the silicone oil layer. CO2 is soluble in silicone oil. Implications of these CO2 and pH effects on mechanisms of corneal deturgescence are discussed.
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PMID:New observations on bicarbonate-pH effects on thickness changes of rabbit corneas under silicone oil in vitro. 393 62

A moderately severe thermal injury of the central cornea of 48 Dutch-belted rabbit eyes was produced with a carbon (CO2) laser. The lesions were photographed with a slit lamp (SL) camera immediately following the injury and at 1, 2, 4, 7, 14, 21, 30 and 60 days after the exposure. Lesion size, opaqueness, and depth were graded clinically by SL biomicroscopy at the same intervals. No significant differences were found (p less than or equal to 0.05) between groups of eyes treated with flurbiprofen (0.03%), prednisolone acetate (1%), and vehicle control four-times-a-day for three weeks following injury. Additionally, eyes were studied histopathologically at 3 and 60 days following injury by light and transmission electron microscopy, and clinically at 30 and 60 days by endothelial specular microscopy. Important clinical and histopathological findings included coagulative necrosis of the corneal epithelium, epithelial sloughing, fusion of stromal collagen, stromal edema and inflammatory cell infiltration, stromal scar formation, corneal thinning, endothelial hyperplasia and metaplasia, fibrinous anterior chamber reaction with hypopyon, and retrocorneal fibrous membrane formation.
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PMID:Laser induced thermal injury of rabbit cornea and treatment with anti-inflammatory agents. 400 71

Evidence exists from both congenital anomalies and animal models that normal fetal lung development is dependent on maintenance of fluid pressure within the developing "airways." Fetal tracheostomy, allowing free egress of airway fluids, results in lung hypoplasia, indicating that some airway distending pressure is required for normal lung development to occur. In contrast, fetal tracheal ligation, which increases fetal airway pressure, reverses lung hypoplasia in animal models. The authors' experiments test the hypothesis that large airway obstruction accelerates the development of murine lungs in vitro in whole-organ culture. Fetuses from time-dated pregnant CD-1 mice at day 14 of gestation were removed (term, 20 days), and the lungs were excised. The left bronchus of each lung was ligated (n = 26), after which the left lung was isolated and cultured at 37 degrees C (95% air, 5% CO2) in BGJb media supplemented with vitamin C and antibiotics. Some fetal lungs were cultured under similar conditions without bronchial ligation (n = 11). After 7 days in culture, the lungs were taken for various analyses. The lungs were fixed in either formaldehyde and processed for paraffin embedding for light microscopic evaluation and morphometric data collection, or were freshly minced and aliquots taken for total protein and DNA content. Several more ligated and unligated lungs were processed for ultrastructural analysis. Morphometric analysis on transverse sections of lungs showed significant differences in the lung tissue size, thickness, epithelial cell height, luminal areas, perimeters, and total number of airspaces (airway + primordial alveolar airspaces). It was evident that bronchial ligation promoted lung development. The ligated lungs displayed thinning of the primordial alveolar walls with cuboidal epithelial cells. The total number of airspaces per field was lower for better developed ligated lungs because of the increased area of airspaces compared with that of the unligated lungs. The dorsoventral tissue thickness (in micrometers) of the ligated lungs was significantly greater than that of the unligated lungs (124.1 +/- 7.0 v 89.6 +/- 8.0); the average outer perimeter of the primordial alveolar airspaces was greater for ligated lungs (404.56 +/- 19.0 microns v 256.85 +/- 17.0 microns). Similarly, the luminal diameter of the spaces of ligated lungs was almost double that of the unligated lungs (38.0 +/- 2.0 microns v 20.3 +/- 2.0 microns), as was the luminal surface area. The morphometric data, which suggest enhanced maturation of the ligated lungs, are supported by results of ultrastructural studies. Ligated lungs had significantly more lamellar bodies. Although total protein and DNA content were greater among the ligated lungs, the protein/DNA ratios did not differ among the groups. The intraluminal pressure (airway pressure) of ligated lungs was 2.9 mm Hg and 3.1 mm Hg at 2 and 4 days in organ culture; the respective pressures for unligated lungs were 1.0 mm Hg and 0.8 mm Hg. These data support the hypothesis that mechanical distending pressure resulting from airway obstruction not only improves pulmonary architecture but also accelerates lung development in vitro. Although these effects have been seen in in vivo models, this is the first proposed in vitro organ culture model. This model may prove to be a powerful tool for the study of molecular mechanisms of mammalian lung development with respect to mechanical and chemical (cytokines, hormones) stimuli.
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PMID:Bronchial ligation enhances murine fetal lung development in whole-organ culture. 881 46

The photosynthesis and productivity of Lemna gibba were studied with a view to its use in Controlled Ecological Life Support Systems (CELSS). Photosynthesis of L. gibba floating on the nutrient solution could be driven by light coming from either above or below. Light from below was about 75% as effective as from above when the stand was sparse, but much less so with dense stands. High rates of photosynthesis (ca. 800 nanomoles CO2 g dry weight (DW)-1 s-1) were measured at 750 micromoles m-2 s-1 PPF and 1500 micromoles mol-1 CO2. This was attained at densities up to 660 g fresh weight (FW) m-2 with young cultures. After a few days growth under these conditions, and at higher densities, the rate of photosynthesis dropped to less than 25% of the initial value. This drop was only partly alleviated by thinning the stand or by introducing a short dark period at high temperature (26 degrees C). Despite the drop in the rate of photosynthesis, maximum yields were obtained in batch cultures grown under continuous light, constant temperature and high [CO2]. Plant protein content was less than reported for field grown Lemna. When the plants were harvested daily, maintaining a stand density of 600 g FW m-2, yields of 18 g DW m-2 d-1 were obtained. The total dry weight of L. gibba included 40% soluble material (sugars and amino acids), 15% protein, 5% starch, 5% ash and 35% cellulose and other polymers. We conclude that a CELSS system could be designed around stacked, alternate layers of transparent Lemna trays and lamps. This would allow for 7 tiers per meter height. Based on present data from single layers, the yield of such a system is calculated to be 135 g DW m-3 d-1 of a 100% edible, protein-rich food.
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PMID:Carbon balance and productivity of Lemna gibba, a candidate plant for CELSS. 1153 89

The paper deals with the deleterious changes at ultrastructural level of the epithelial cells of gills of Cyprinus carpio communis Linn. upon exposure to 1/10th of LC50 of monocrotophos which is considered to be insignificant concentration from toxicological point of view. The gills of the fish are the primary corridor formolecularexchange between the internal milieu of a fish and its environment. Gills perform numerous functions such as oxygen uptake and CO2 excretion, osmoregulation, acid-basic balance, excretion of nitrogenous compounds and taste. Hazardous chemicals present in water may alter the morphology of the epithelial cells of gills of the fish, which may affect the process of diffusion of gases and ultimately the overall health of the fish. To prove this fact Cyprinus carpio communis Linn. was kept in water for 30 days having low concentration of 0.038 ppm (1\10th of LC50) of monocrotophos and an attempt was made to study the different types of degenerations produced in the epithelial cells of gills as compared to the normal epithelial cells of gills of this culturable fish using Scanning Electron Microscope (SEM) technique. The ultrastructural changes due to the toxic exposure at finer scale were thinning of microridges, upliftment of epithelial cells, development of hyperplasia, decrease in the density of mucous cells which are considered to be the first line of defence and total dystrophy of epithelial tissue. Thus, it is opined that a low concentration of monocrotophos has the potential to bring different type of degenerations at finer scale hence affecting the fish's health drastically and altering the fitness of the fish in water even having insignificant amount of this toxicant in the ambient water
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PMID:Impact of low dose of organophosphate, monocrotophos on the epithelial cells of gills of Cyprinus carpio communis Linn.--SEM study. 1838 92

New Zealand is unique in that half of its national greenhouse gas (GHG) inventory derives from agriculture--predominantly as methane (CH4) and nitrous oxide (N2O), in a 2:1 ratio. The remaining GHG emissions predominantly comprise carbon dioxide (CO2) deriving from energy and industry sources. Proposed strategies to mitigate emissions of CH4 and N2O from pastoral agriculture in New Zealand are: (1) utilising extensive and riparian afforestation of pasture to achieve CO2 uptake (carbon sequestration); (2) management of nitrogen through budgeting and/or the use of nitrification inhibitors, and minimizing soil anoxia to reduce N2O emissions; and (3) utilisation of alternative waste treatment technologies to minimise emissions of CH4. These mitigation measures have associated co-benefits and co-costs (disadvantages) for rivers, streams and lakes because they affect land use, runoff loads, and receiving water and habitat quality. Extensive afforestation results in lower specific yields (exports) of nitrogen (N), phosphorus (P), suspended sediment (SS) and faecal matter and also has benefits for stream habitat quality by improving stream temperature, dissolved oxygen and pH regimes through greater shading, and the supply of woody debris and terrestrial food resources. Riparian afforestation does not achieve the same reductions in exports as extensive afforestation but can achieve reductions in concentrations of N, P, SS and faecal organisms. Extensive afforestation of pasture leads to reduced water yields and stream flows. Both afforestation measures produce intermittent disturbances to waterways during forestry operations (logging and thinning), resulting in sediment release from channel re-stabilisation and localised flooding, including formation of debris dams at culverts. Soil and fertiliser management benefits aquatic ecosystems by reducing N exports but the use of nitrification inhibitors, viz. dicyandiamide (DCD), to achieve this may under some circumstances impair wetland function to intercept and remove nitrate from drainage water, or even add to the overall N loading to waterways. DCD is water soluble and degrades rapidly in warm soil conditions. The recommended application rate of 10 kg DCD/ha corresponds to 6 kg N/ha and may be exceeded in warm climates. Of the N2O produced by agricultural systems, approximately 30% is emitted from indirect sources, which are waterways draining agriculture. It is important therefore to focus strategies for managing N inputs to agricultural systems generally to reduce inputs to wetlands and streams where these might be reduced to N2O. Waste management options include utilizing the CH4 resource produced in farm waste treatment ponds as a source of energy, with conversion to CO2 via combustion achieving a 21-fold reduction in GHG emissions. Both of these have co-benefits for waterways as a result of reduced loadings. A conceptual model derived showing the linkages between key land management practices for greenhouse gas mitigation and key waterway values and ecosystem attributes is derived to aid resource managers making decisions affecting waterways and atmospheric GHG emissions.
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PMID:Climate change mitigation for agriculture: water quality benefits and costs. 1909 84

Depending on management, forests can be an important sink or source of carbon that if released as CO2 could contribute to global warming. Many forests in the western United States are being treated to reduce fuels, yet the effects of these treatments on forest carbon are not well understood. We compared the immediate effects of fuels treatments on carbon stocks and releases in replicated plots before and after treatment, and against a reconstruction of active-fire stand conditions for the same forest in 1865. Total live-tree carbon was substantially lower in modern fire-suppressed conditions (and all of the treatments) than the same forest under an active-fire regime. Although fire suppression has increased stem density, current forests have fewer very large trees, reducing total live-tree carbon stocks and shifting a higher proportion of those stocks into small-diameter, fire-sensitive trees. Prescribed burning released 14.8 Mg C/ha, with pre-burn thinning increasing the average release by 70% and contributing 21.9-37.5 Mg C/ha in milling waste. Fire suppression may have incurred a double carbon penalty by reducing stocks and contributing to emissions with fuels-treatment activities or inevitable wildfire combustion. All treatments reduced fuels and increased fire resistance, but most of the gains were achieved with understory thinning, with only modest increases in the much heavier overstory thinning. We suggest modifying current treatments to focus on reducing surface fuels, actively thinning the majority of small trees, and removing only fire-sensitive species in the merchantable, intermediate size class. These changes would retain most of the current carbon-pool levels, reduce prescribed burn and potential future wildfire emissions, and favor stand development of large, fire-resistant trees that can better stabilize carbon stocks.
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PMID:Fire suppression and fuels treatment effects on mixed-conifer carbon stocks and emissions. 1976 88


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