In the management of hydrocephalus by shunts, two valve types are currently available:1) differential pressure valves(DPV) which provide a constant resistance and allow CSF flow when the proximal hydrostatic pressure exceeds the valve's present closing pressure, and 2) the newer variable resistance flow regulated valve(FRV). Eighty one cases of hydrocephalus were reviewed in this study to compare the two devices. Forty two patients were operated with FRV and 39 patients were operated with DPV. This study compared the preoperative and postoperative KPS score, ventricular size, periventricular low densities, and the frequency of complications. We have conclude that 1) In group 1(KPS score 50-70), FRV is useful and in group 2(KPS score 20-40), DPV is useful, 2) FRV is useful in dealing with excessively reduced ICP caused by over-drainage of a ventricular shunt;it can prevent postshunt subdural hygroma and symptomatic slit ventricles. 3) For evaluation of the effectiveness of FRV, the decrease of periventricular low densities is a more valuable index than the change of ventricle size(Hydrocephalus index).
Humans ; Hydrocephalus ; Hydrostatic Pressure ; Subdural Effusion ; Ventriculoperitoneal Shunt*

BACKGROUND: An entry of needle into the epidural space has been identified by the development of negative pressure to the advancing needle; hanging drop, loss of resistance, or use of Macintosh balloon. But it is suspicious that epidural space is a true negative pressure space. METHODS: We measured the epidural pressures of pregnant patients in right lateral decubitus (RLD) and sitting position and compared with the values of non-pregnant patients of respective position. 17G Tuohy needle with closed system was used, the pressure of which was zeroed to the puncture level at third lumbar intervertebral space. RESULTS: Epidural pressures were positive in all subjects. Values of measurement were 13+/-4mmHg, 15+/-7mmHg, 16+/-6mmHg and 25+/-7mmHg for pregnant-RLD, pregnant-sitting, non-pregnant-RLD, and non-pregnant-sitting group, respectively. CONCLUSIONS: There was a significant difference between RLD and sitting position in non-pregnant patient only (p<0.05). It is suggested that the hydrostatic pressure of CSF above puncture level and the hydrostatic pressure of valveless epidural venous plexus blood influenced the epidural pressure of non-pregnant group in sitting position. But in pregnant group, abdominal mass may have elicited a draining effect on epidural venous plexus during lumbar flexion in sitting position and partially nullified the hydrostatic pressure of CSF and blood.
Epidural Space ; Humans ; Hydrostatic Pressure ; Needles ; Pregnancy ; Punctures

Mechanics plays an important role in regulating cell function. Hydrodynamics has become a hot topic of research in recent years. As an important factor, hydrodynamic pressure has significant influence on the form, cytoskeleton, proliferation, apoptosis and secretion function of cells. Many researches indicated that there are close relationships between kidney diseases and hydrodynamics which should be studied deeply.
Apoptosis ; physiology ; Cell Proliferation ; Cytoskeleton ; physiology ; Humans ; Hydrodynamics ; Hydrostatic Pressure ; Kidney ; cytology ; Pressure

Pneumothorax and pulmomary edema can be produced as a complication during general anesthesia. The former which occurs during pressure ventilation is highly dangerous. It is characterized by a dramatic onset which is readily recongnized and demands immediate management. The latter may be developed after the upper airway obstruction has been relived due to the reduction of the intersitial hydrostatic pressure and increased capilary permeability. We experienced a case of pneumothorax and pulmonary edema that occurred after treatment for upper airway obstruction.
Airway Obstruction* ; Anesthesia, General ; Edema ; Hydrostatic Pressure ; Permeability ; Pneumothorax* ; Pulmonary Edema* ; Ventilation

PURPOSE: Articular cartilage is under continuous mechanical stresses during daily activity. The mechanical force must also be applied during the culturing process to produce a phenotypically correct tissue. We have developed bioreactor, capable to apply the three main fluid-induced stresses: shear stress, compression, and hydrostatic pressure. The objective of this study was to investigate the effects of bioreactor on chondrocyte proliferation and matrix synthesis in articular chondrocytes and to determine the most appropiate chondrogenesis biomechanical environment. MATERIALS AND METHODS: Articular cartilage was harvested from the rabbit knee. Isolated chondrocytes from articular cartilage were cultured in static culture and bioreactor culture. Bioreactor culture condition was fluid rate of 0.2 cm/sec and shear stress of 0.6x10-3 dyn/cm2 After 3 days, the effects of fluid-induced shear stress were evaluated by measuring the cell proliferation, observation of cell morphology and expression of cartilage specitic ECM using Histology, and Immunocytochemistrical staining. RESULTS: We have developed bioreactor and subjected chondrocytes to fluid-induced shear stress of 0.6x10-3 dyn/cm2 for 3 days. We observed changes in chondrocyte shape, orientation, and nodule formation. In metabolic studies, the application of fluid-induced shear stress to articular chondrocytes resulted in a significant increase in the proliferation of chondrocytes and the synthesis of type II collagen compared to that of in the static culture. CONCLUSION: From these results, it was concluded that the bioreactor which we developed produced appropriate chondrogenesis biomechanical environment.
Bioreactors* ; Cartilage ; Cartilage, Articular ; Cell Proliferation ; Chondrocytes ; Chondrogenesis ; Collagen Type II ; Hydrostatic Pressure ; Knee ; Stress, Mechanical

The aim of this study was to measure the dentinal tubular fluid flow (DFF) during and after amalgam and composite restorations. A newly designed fluid flow measurement instrument was made. A third molar cut at 3 mm apical from the CEJ was connected to the flow measuring device under a hydrostatic pressure of 15 cmH2O. Class I cavity was prepared and restored with either amalgam (Copalite varnish and Bestaloy) or composite (Z-250 with ScotchBond MultiPurpose: MP, Single Bond 2: SB, Clearfil SE Bond: CE and Easy Bond: EB as bonding systems). The DFF was measured from the intact tooth state through restoration procedures to 30 minutes after restoration, and re-measured at 3 and 7days after restoration. Inward fluid flow (IF) during cavity preparation was followed by outward flow (OF) after preparation. In amalgam restoration, the OF changed to IF during amalgam filling and slight OF followed after finishing. In composite restoration, application CE and EB showed a continuous OF and air-dry increased rapidly the OF until light-curing, whereas in MP and SB, rinse and dry caused IF and OF, respectively. Application of hydrophobic bonding resin in MP and CE caused a decrease in flow rate or even slight IF. Light-curing of adhesive and composite showed an abrupt IF. There was no statistically significant difference in the reduction of DFF among the materials at 30 min, 3 and 7 days after restoration (P > 0.05).
Adhesives ; Bisphenol A-Glycidyl Methacrylate ; Dentin ; Hydrostatic Pressure ; Molar, Third ; Paint ; Resin Cements ; Tooth ; Tooth Cervix

The typical radiographic findings of pulmonary edema from the increased hydrostatic pressure shows centrally localized consolidation, which is known as a "butterfly or bat's wing" pattern. These terms describe the anatomic distribution of edema that uniformly involve the hilum and medulla of the lung but not the peripheral region of the lung parenchyma (cortex). We present a case of butterfly wing-like pulmonary edema on a chest radiograph by mitral regurgitation due to an idiopathic chordal rupture.
Butterflies ; Chordae Tendineae ; Edema ; Hydrostatic Pressure ; Lung ; Mitral Valve Insufficiency ; Pulmonary Edema* ; Radiography, Thoracic ; Rupture*

PURPOSE: To compare the choroidal thickness in central serous chorioretiopathy (CSC) patients and normal controls using spectral domain optical coherence tomography (SD-OCT). METHODS: The authors compared the choroidal thickness in eyes with CSC, fellow eyes and in normal eyes. In addition, the authors attempted to determine any correlation between choroidal thickness and other factors such as age, height of serous retinal detachment, and spherical equivalent. Choroidal thickness was measured using a perpendicular line from the outer margin of the subfoveal retinal pigment epithelium to the inner surface of the sclera. RESULTS: Twenty-five eyes of 25 CSC patients, 17 fellow eyes and 29 age-matched normal eyes were examined and categorized as group 1, group 2 and group 3, respectively. Subfoveal choroidal thickness was 370.64 +/- 58.06 microm in group 1, 301.85 +/- 47.83 microm in group 2, and 261.84 +/- 48.22 microm in group 3. The choroidal thickness in group 1 was significantly greater than those in group 2 and group 3, and the choroidal thickness in group 2 was significantly greater than that in group 3 (p = 0.001, p < 0.001, p = 0.004, respectively), where the choroidal thickness showed a negative correlation with age (p = 0.015). CONCLUSIONS: The choroidal thickness was greater in eyes with CSC and in their fellow eyes compared to that in normal eyes. The results suggest that CSC may be caused by choroidal vascular hyperpermeability and increased hydrostatic pressure in the choroid.
Central Serous Chorioretinopathy ; Choroid ; Eye ; Humans ; Hydrostatic Pressure ; Retinal Detachment ; Retinal Pigment Epithelium ; Tomography, Optical Coherence

PURPOSE: In this study, we investigated the potential of injectable hydrogel scaffolds for the regeneration of nucleus pulposus. MATERIALS AND METHODS: We prepared injectable hydrogels [Chitosan-Pluronic (CP), CP/Osteogenic Protein-1 (CP/OP-1), CP/Gly-Arg-Gly-Asp-Ser (CP/GRGDS), CP/GRGDS/OP-1] for this study. One of the four potential materials was selected through the cell viability tests. For each material, primary cultured nucleus pulposus (NP) cells from New Zealand rabbits were seeded onto each material. For the investigation of the effects of mechanical stimulation, the commercially available bioreactor was used. 0.2 MPa of intermittent hydrostatic pressure was imposed for 3 days after 7th day of seeding with the pattern of 2 min and 15 min for stimulating and resting, respectively. The specimens were harvested at 1, 10, 14 day after seeding for analyses. RESULTS: The MTT assay for 5 days revealed that CP/OP-1 group showed significant increase. The other two groups (CP/GRGDS and CP/GRGDS/OP-1) showed that the proliferation rate increased until 3 days after culture, while it decreased on day 5. The mechanical stimuli induced higher amounts of DNA measured in CP/OP- 1 on day 5 after culture. However, no significant difference was observed between two groups. CONCLUSION: We came to the conclusions that the biochemical environment as well as mechanical stimulation may play an important role in regenerating nucleus pulposus matrix, especially in CP/OP-1 in this study. However, further study are recommended in relation to mechanical effects as well as biochemical conditions.
Bioreactors ; Cell Survival ; DNA ; Hydrogel ; Hydrogels ; Hydrostatic Pressure ; Intervertebral Disc ; Porphyrins ; Rabbits ; Regeneration ; Seeds

Pulmonary edema is well recognized complication of acute upper airway obstruction, especially in small children, but rarely seen in adults. It usually follows relief of the obstruction and is likely to be of noncardiogenic origin. The mechanism by which an upper airway obstruction causes pulmonary edema is likely due to the combination of the increased reductions in the interstitial hydrostatic pressure and increased capilary permeabillity. Hypoxia is another aggravating factor. We present a case of acute pulmonary edema caused by laryngospasm that occurred in an adult patient after treatment for upper airway obstruction following extubation of the traches.
Adult* ; Airway Obstruction* ; Anoxia ; Child ; Humans ; Hydrostatic Pressure ; Laryngismus ; Lung ; Pulmonary Edema*