Fluid Pressure Measurements Research Articles

Safety, Efficacy, and Biomarker Exploration in a Phase II Study of Bevacizumab, Oxaliplatin, and Gemcitabine in Recurrent Müllerian Carcinoma

ObjectiveTo explore the safety, efficacy, and biomarkers of bevacizumab with gemcitabine and oxaliplatin in women with recurrent platinum-sensitive ovarian carcinoma. MethodsThe patients received bevacizumab (10 mg/kg), gemcitabine (1000 mg/m2), and oxaliplatin (65 mg/m2) on days 1 and 15 in 28-day cycles. The patients with safely accessible tumor underwent intratumoral fluid pressure (IFP) measurements and positron-emission tomographies immediately and 2 weeks after treatment. Blood biomarkers were evaluated at 5 time points. ResultsThe trial was closed after enrolling 19 of the 53 projected patient accrual. Thirteen (68.5%) of 19 patients showed a response (1 complete response, 12 partial responses), and 6 patients showed stable disease (31.6%). Median progressive-free survival was 36.9 weeks (258.3 days), and the median overall survival was 112.3 weeks (633 days, not reached). Toxicity was acceptable, and there were no arterial thromboses, serious bleeding, gastrointestinal perforations, or complications from the invasive procedures. Bevacizumab with chemotherapy induced a substantial drop in tumor IFP after treatment. The regimen induced sustained elevation in circulating plasma vascular endothelial growth factor (VEGF), placental growth factor (PlGF), basic fibroblast growth factor (bFGF), soluable vascular endothelial growth factor receptor 2 (sVEGFR2), and circulating progenitor cells. Plasma PlGF, VEGFR2+ monocytes, and urinary matrix metalloproteinase 2 activity showed differential associations with treatment outcome when evaluated at baseline and after 14 days of treatment. ConclusionsDespite early termination of the study, the results indicate that the regimen was well tolerated and demonstrated activity in platinum-sensitive ovarian cancer. Biomarker evaluations showed that bevacizumab with chemotherapy significantly changed the levels of several circulating cellular and molecular biomarkers. The increases in plasma PlGF and VEGFR2+ monocytes showed correlations with outcome. These exploratory data should be further evaluated in future studies of bevacizumab in ovarian cancer.

A batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement

In this paper, we present the design, fabrication and test of a batch fabricated capacitive pressure sensor with an integrated Guyton capsule for interstitial fluid pressure measurement. The sensor is composed of 12 µm thick single crystalline silicon membrane and a 3 µm gap, hermetically sealed through silicon–glass anodic bonding. A novel batch scale method for creating electrical feed-throughs inside the sealed capacitor chamber is developed. The Guyton capsule consists of an array of 10 µm diameter access holes etched onto a silicon back-plate separated from the silicon sensing membrane by a gap of 5 µm. The presence of the Guyton capsule (i.e. plates with access holes plus the gap separating them from the sensing membrane) allows for the ingress of interstitial fluid inside the 5 µm gap following the implantation, thus, providing an accurate measurement of interstitial fluid pressure. The fabricated sensor is 3 × 2 × 0.42 mm3 in dimensions and has a maximum sensitivity of 10 fF mmHg−1.

Trans-lamina cribrosa pressure difference correlated with neuroretinal rim area in glaucoma

The aim of this work is to prospectively assess the relationship between trans-laminar cribrosa pressure difference and neuroretinal rim area as morphologic surrogate of glaucomatous optic nerve damage. The study included 22 patients with high-pressure glaucoma, 13 patients with normal-pressure glaucoma, and 17 subjects with ocular hypertension. All participants underwent a standardized ophthalmologic examination including confocal laser scanning tomography of the optic nerve head and computerized perimetry and a neurologic examination including measurement of the lumbar cerebrospinal fluid (CSF) pressure. The trans-lamina cribrosa pressure difference was calculated as difference of intraocular pressure minus lumbar CSF pressure. Neuroretinal rim area (p = 0.006; correlation coefficient r = -0.38) and mean visual field defect (p = 0.008; r = 0.38) were significantly associated with trans-lamina cribrosa pressure difference. The probability of error was lower (i.e., the pvalue were lower) and the correlation coefficients were higher for the associations between rim area/visual field defect with trans-lamina cribrosa pressure difference than for the associations between rim area/visual field defect and intraocular pressure or lumbar CSF pressure. The trans-lamina cribrosa pressure difference as the difference of intraocular pressure minus the lumbar CSF pressure was the main pressure parameter associated with the amount of glaucomatous optic nerve damage. This may suggest that the CSF pressure as trans-lamina cribrosa counter pressure against the intraocular pressure may play some role in the pathogenesis of glaucomatous optic neuropathy.

In Situ Measurement of Fluid Pressure at the Wafer-Pad Interface during Chemical Mechanical Polishing of 12-inch Wafer

In this paper, a novel in-situ interfacial fluid pressure measurement system is developed for the practical chemical mechanical polishing (CMP) equipment, in which the pressure sensors are equidistantly embedded in the platen along the radial direction and sweep beneath the wafer surface during CMP. Interfacial fluid pressure mapping is realized for standard 12″ blanket wafers at the down pressure of 0.5 ∼ 2.0 psi. The fluid pressure profiles from the leading edge to the trailing edge and the pressure contour maps of the fluid film across the whole wafer surface are constructed and displayed. Results reveal a large positive pressure region located near the wafer trailing edge and a small negative pressure region located near the leading edge, which is quite different from the negative dominated results of previous studies. The fluid pressure can support 15% ∼ 30% of the applied pressure. The down pressure has great effect on the fluid pressure due to the wafer's bend under the applied load. When the down pressure increases, the positive pressure region expands and slightly shifts toward the outer of the pad while the negative pressure region shrinks.

A Novel Real-Time Capacitance Estimation Methodology for Battery-Less Wireless Sensor Systems

This paper presents a novel method to read a passive capacitive sensor in telemetry by using inductive coupling. While classical inductive coupling approaches measure sensor capacitance by identifying the resonant frequency of the sensor with a sweep of radio frequency (RF) signals, the proposed method estimates the capacitance change in real-time by algebraically manipulating two measurements (the magnitude and the phase of the reflected sensor impedance). Only one RF signal is used in the proposed method instead of a frequency sweep. Analysis is provided to show that some physical parameter errors can deteriorate the capability of the proposed method in accurately measuring sensor capacitance. However, the use of a first order calibration procedure based on error analysis overcomes this shortcoming. Extensive experimental results with the proposed method combined with a first order calibration show that multifrequency and rapid changes in sensor capacitance can be estimated reliably under varying locations and orientations of the interrogator. The battery-less wireless sensors enabled by the developed technology in this paper can be widely used for measurement of fluid pressure, force, acceleration and other capacitance-change based sensor measurements.

Pore fluid pressure and internal kinematics of gravitational laboratory air‐particle flows: Insights into the emplacement dynamics of pyroclastic flows

The emplacement dynamics of pyroclastic flows were investigated through noninvasive measurements of the pore fluid pressure in laboratory air‐particle flows generated from the release of fluidized and nonfluidized granular columns. Analyses of high‐speed videos allowed for correlation of the pressure signal with the flow structure. The flows consisted of a sliding head that caused underpressure relative to the ambient, followed by a body that generated overpressure and at the base of which a deposit aggraded. For initially fluidized flows, overpressure in the body derived from advection of the pore pressure generated in the initial column and decreased by diffusion during propagation. Relatively slow diffusion caused the pore pressure in the thinner flow to be larger than lithostatic at early stages. Furthermore, partial auto‐fluidization, revealed in initially nonfluidized flows, also occurred and contributed to maintain high pore pressure, whereas dilation or contraction of the air‐particle mixture with associated drag and/or pore volume variation transiently led the pressure to decrease or increase, respectively. The combination of all these processes resulted in long‐lived high pore fluid pressure in the body of the flows during most of their emplacement. In the case of the initially fluidized and slightly expanded (∼3–4%) flows, (at least) ∼70%–100% of the weight of the particles was supported by pore pressure, which is consistent with their inertial fluid‐like behavior. Dense pyroclastic flows on subhorizontal slopes are expected to propagate as inertial fluidized gas‐particle mixtures consisting of a sliding head, possibly entraining basement‐derived clasts, and of a gradually depositing body.

Laser-pulse interferometry applied to high-pressure fluid flow in micro channels

The miniaturization of hydraulic systems together with ever increasing static and dynamic fluid pressure as is happening in fuel injection systems leads to complex flow effects with very high local and temporal pressure gradients. System optimization for hydraulic efficiency, components durability or spray formation quality needs the understanding of relevant flow properties. Fluid flow simulation models support such understanding, but with the complex nature of flow conditions, they are in need for precise and comprehensive verification and validation data. This work reports on measurement methods and analysis results for local fluid density and pressure measurements under overall stationary, highly turbulent and cavitating flow conditions in planar, optically accessed, model flow experiments. Laser-pulsed interferometry is applied for the measurement of fluid density fields under high spatial (∼3 μm) and temporal (∼5 ns) resolution. Interferometric imaging and image evaluation techniques provide ensemble mean pressure field data, local pressure fluctuation and differential pressure data. This yields information about local flow features such as flow vortex generation frequency, spatial size and shape of vortices and local pressure distribution inside of vortex structures. Features of bubble collapse process and corresponding pressure shock waves have been observed. The analysis method is applied to a forward-facing step and a target flow geometry. Experimental method, evaluation procedures and results are presented in this paper.

Cerebrospinal Fluid Pressure Measurement in the Ovine Intrathecal Space: A Preliminary Study towards the Diagnosis of Intrathecal Drug Administration Catheter Dislodgement or Occlusion

Background and Objective: Intrathecal drug delivery catheter malfunctions are a principal cause of therapy interruption. We determined that normal baseline intrathecal cerebrospinal fluid (CSF) pressure recordings could be obtained in an ovine model and in a catheter dislodgement scenario. Methods: Two sheep were implanted with spinal catheters: 2 in the T₆ epidural space in sheep No. 1; 1 T₆ intrathecal catheter plus 1 L₂ epidural catheter with a deliberate CSF leak to simulate dislodgement in sheep No. 2. Pressure waves were recorded intraoperatively and at multiple times after the implantation in the awake condition. On day 21, the animals were anesthetized for pressure recordings while on and temporarily off mechanical ventilation. They were then necropsied. Results: CSF pressure waves were obtained in this animal model under anesthesia with or without mechanical ventilation and in the awake state. Fluid accumulation at the tip of a dislodged (epidural) catheter temporarily caused apparent coupling of fluid pressures across the dura. An unintentional extraspinal fluid collection in sheep No. 2 was associated with a raised baseline epidural pressure. Conclusions: These findings support the notion that pressure sensors can play a role in determining the status of intraspinal drug delivery catheters.

Measurement of interstitial fluid pressure (IFP) and circulating biomarkers in soft tissue sarcoma (STS): An exploratory phase II clinical and correlative study of sorafenib (SOR) in patients with refractory STS (NCI Protocol 6948).

10091 Background: Interstitial hypertension may contribute to chemo-resistance in STS. Sorafenib is a small molecule tyrosine kinase inhibitor with potent activity against c-RAF/B-RAF, VEGFR-2, and PDGFR-β. By affecting vascular permeability, SOR may potentially reduce IFP. We assessed anti-tumor activity and measured the IFP and circulating biomarkers in patients with superficial refractory STS treated with SOR. Methods: Eligibility criteria included advanced/metastatic STS with no known curative therapy, measurable disease with at least one superficial lesion (>1cm) amenable to biopsy, age ≥18, ECOG performance status ≤2, and no prior SOR therapy. SOR was administered at 400mg BID. IFP measurements were performed intraoperatively as described (Boucher et al 1991); plasma biomarkers were collected pre- and on Day 28 post-SOR. Results: Fifteen patients (median age 59, range 30-84) were enrolled, 14 of whom had prior chemotherapy and/or radiation. Median tumor size was 6.6cm (range 1.3-10.7cm). Common sarcoma sub-types included leiomyosarcoma (27%), myxofibrosarcoma (13%) and synovial sarcoma (13%). Of these, 11 had superficial tumor amenable to biopsy. In this group, median TTP was 28 days (range 10-81). In four pts lacking palpable superficial tumor, mean TTP was 173 days (range 28-227). Best response was stable disease in 10 of 15 pts, maintained for a median 57 days (range 20-168 days). IFP measurements were obtained in 6 pts at baseline and showed a direct correlation with tumor size (Kendall's tau=0.87, p=0.017). Two pts with SD had corresponding post-SOR IFP evaluation and demonstrated a decline in IFP. SOR significantly increased plasma VEGF, PlGF and SDF-1a and decreased sVEGFR2 (p<0.05 for all). Conclusions: SOR has modest benefits in this population, most of whom had advanced refractory disease. IFP appears to decrease when response is maintained. Biomarker changes were consistent with inhibition of angiogenesis by SOR. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Amgen, ARIAD, ArQule, AstraZeneca, Bayer, Daiichi Sankyo, Dyax, Genentech, Infinity, Johnson & Johnson, Millennium, Novartis, Pfizer, PharmaMar, Regeneron, Roche, SynDevRx, ZIOPHARM Oncology SynDevRx Novartis, Pfizer, PharmaMar Amgen, ARIAD, ArQule, Daiichi Sankyo, Genentech, Infinity, Johnson & Johnson, Novartis, Pfizer, PharmaMar, Roche, ZIOPHARM Oncology ARIAD, ArQule, Daiichi Sankyo, Infinity, Johnson & Johnson, PharmaMar

Perioperative Continuous Cerebrospinal Fluid Pressure Monitoring in Patients with Spontaneous Cerebrospinal Fluid Leaks: Presentation of a Novel Technique

A few studies have used direct measurements of cerebral spinal fluid pressure (CSFP) using either lumbar punctures or pressure transducers to evaluate CSFP elevations as a potential etiology in patients with spontaneous CSF leaks. Limitations of these techniques include positional variation, inadequate duration of measurement, and insufficient analysis of waveforms. We propose a novel technique for more accurate measurement of CSFP in patients with spontaneous CSF leaks. Patients with spontaneous CSF rhinorrhea had a lumbar catheter placed for 24-hour CSFP recording before and 72 hours after their endoscopic surgical repair. Heart rate, electrocardiogram, respirations, and oxygen saturation are recorded in addition to CSFP. Mean CSFP as well as the pulse waveform amplitude were calculated. Twelve patients with spontaneous CSF rhinorrhea underwent continuous CSFP monitoring. Seven patients had elevations in their CSFP of >25 cm H(2)O for at least 4% of their recording time during their continuous monitoring. Nine patients had significant oxygen desaturations associated with elevated CSFP. Pulse waveform amplitudes could average 20 cm H(2)O over several minutes in patients with mean CSFP of <10 cm H(2)O. Perioperative CSFP monitoring provides continuous data including mean and transient elevations in CSFP that can be correlated to other measurements such as oxygen saturation. This data may more accurately identify those CSF leak patients with elevated CSFP as well as correlate these elevations to prognostic clinical information that may improve treatment and outcome after their surgical repair.

산업공정상의 유체 유동 모니터링 시스템 설계 및 구현

본 논문에서는 MFC(Mass Flow Controller) 유닛으로부터 전송된 유체의 압력을 모니터하고 흐름 제어 기능을 수행하는 유체 유동 모니터링 시스템을 제안한다. 이 시스템은 MFC 유닛과 채널 디바이스, 모니터 및 관리 소프트웨어로 구성된다. MFC 유닛은 유체 압력 값을 측정하여 채널 디바이스로 전송하고, 채널 디바이스는 MFC 유닛과 모니터 및 관리 소프트웨어간의 입출력 인터페이스를 제공하는 기능을 한다. 모니터 및 관리 소프트웨어는 각 채널의 MFC 유닛에서 실시간으로 측정한 유체 압력 값을 모니터링하여 분석하고 제어한다. 이 소프트웨어는 20개의 채널과 0.1의 모니터링 주기로 구성하여 1초당 200개 즉, 1시간당 72만개의 데이터를 처리한다. 이때 입력 데이터 수의 증가에 따라 저장 공간도 비례하여 증가한다. 이러한 데이터 수의 증가와 저장 공간의 증가는 데이터 조회 성능을 저하시키기 때문에 데이터를 효율적으로 관리할 수 있는 변경값 감지 기법과 변경 범위 감지 기법으로 구현한다. In this paper, we propose an industrial fluid monitoring system which performs the flow control function and monitors fluid pressure transmitted from MFC(Mass Flow Controller) unit. This system consists of MFC unit, channel device, and monitoring management software. MFC unit transmits the measured data of the fluid pressure to the channel device which would provide the input/output interface between management software, monitoring and MFC unit. The monitoring and management software control and analyze by monitoring real time measurements of fluid pressure from each channel of MFC unit. This software can process 20 channels and 0.1 monitoring cycle which gives 200 data measurement per second (i.e., 720,000 data/hour). At this time, the storage space increases in proportion to the rise of input data. This growth of data and storage space makes loss of data access efficiency. Therefore, it demands the implementation by sensing scheme of change scope and data, which can effectively manage the data.

Abstract LB-380: Apo2L/TRAIL reduces interstitial fluid pressure and enhances gemicitabine uptake in patient pancreatic tumor xenografts

Abstract Tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) has promising anti-tumor therapeutic potential and is in clinical trials. It is known that microenvironmental factors such as elevated interstitial fluid pressure limits uptake and greatly inhibits anti-tumor efficacy of many therapeutics. We are investigating the role of interstitial fluid pressure in the anti-tumor effect of Apo2L/TRAIL alone and in combination with gemcitabine. We first carried out a histological analysis of Colo205 tumors treated with a single 1000 g dose of Apo2L/TRAIL. Apoptosis (ck18+ cells) and infiltration of macrophages (F4/80+ cells) peaks by 8 hrs; by 24 and 48 hours, apoptotic debris has been cleared and the lumen of tumor vessels is clearly apparent. This is in sharp contrast to untreated tumors in which cells are densely packed and vessels with an open lumen are seldom seen. Correspondingly, measurements of tumor interstitial fluid pressure (IFP) taken 48 hrs after a single treatment of Apo2L/TRAIL revealed a significant reduction in IFP compared to tumors in the untreated mice (n=5; 0.3 cm H2O vs. 3.4 cm H2O, P= 0.002). We have characterized the Apo2L/TRAIL sensitivity of a panel of patient pancreatic tumor xenografts and found a range of responses to Apo2L/TRAIL from actual regression (tumor growth inhibition, TGI, of 108%) to complete resistance (TGI of 0%). Histological analysis of a sensitive tumor showed that Apo2L/TRAIL induced both the physical changes seen in Colo205 as well as a similarly significant reduction in IFP (n=7; P= 0.003). Importantly, in these patient xenografts, combination therapy with Apo2L/TRAIL and chemotherapy has been shown to enhance the antitumor effect of gemcitabine. Therefore, we investigated the effect of Apo2L/TRAIL induced lowering of IFP on gemcitabine uptake. In these studies, a single dose of gemcitabine was administered 48 hrs after Apo2L/TRAIL administration. Pharmacological analysis reveals a 33% increase in gemcitabine uptake in tumors in the 6 hours following Apo2L/TRAIL administration; no such increase was observed in normal liver. These results support the idea that pretreatment of a tumor with Apo2L/TRAIL leads to “decompression” of the tumor and will selectively improve tumor uptake of chemotherapeutics. We are currently investigating different schedules of administration in order to maximize the uptake of gemcitabine and optimize the anti-tumor efficacy of this combination therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-380.

Abstract 4472: NVP-BKM120, a pan class I PI3K inhibitor impairs microvascular permeability and tumor growth as detected by DCE-MRI and IFP measurements via radio-telemetry: Comparison with NVP-BEZ235

Abstract Tumor blood vessels are distinctly abnormal in structure and function. When compared to normal vessels, they are enlarged and tortuous and leaky, poorly covered by pericytes and with a defective basement membrane. VEGF is a prominent cytokine responsible for the hyperpermeable state of tumor microvasculature to plasma macromolecules. The phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway functions downstream of VEGF and can activate the production of the free radical gas nitric oxide (NO) through the enzyme endothelial NO synthase (eNOS), a key player for the in vivo biological activity of VEGF. In the present study, we investigated the effect of NVP-BKM120, a novel, synthetic low molecular mass compound, which potently inhibits class I PI3K activity, on vascular leakage in tumors and its impact on tumor progression in an orthotopic breast cancer model (BN472) in syngeneic rats. Effects on the vasculature were investigated in normal and tumor tissues with a variety of technologies: dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), tumor interstitial fluid pressure (IFP) measurements in conscious animals via radio-telemetry and a modified Miles assay, representing non invasive, minimally invasive and invasive methods, respectively. Tumor histology and western blots were used to confirm pathway inhibition. For comparison, the effect of NVP-BEZ235, a potent pan class I PI3K and mTOR activity inhibitor, was assessed head-to-head in the same experiments. BKM120 induced significant decreases in VEGF-induced vascular leakage in normal and tumor tissues. These effects were similar to those obtained following BEZ235 treatment. Western blot of total ear lysates from treated mice clearly demonstrated pathway inhibition. The inhibition of vessel permeability observed with BEZ235 and BKM120 correlated with their respective anti-tumor activities, IFP change and Ktrans (vascular permeability transfer constant measured by DCE-MRI) decrease. In conclusion, our data demonstrate that in BN472 tumors, BKM120 significantly decreases tumor microvascular leakage similar to BEZ235 at equipotent antitumor dose. Changes in Ktrans may be a useful independent clinical surrogate biomarker for NVP-BKM120 efficacy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4472.

Interstitial Fluid Pressure as a Prognostic Factor in Cervical Cancer Following Radiation Therapy

To investigate tumor interstitial fluid pressure as a prognostic factor for recurrence-free survival in patients with cervical cancer following radiation therapy. Tumor interstitial fluid pressure was measured in 55 cervical cancer patients who received radiation therapy between August 1998 and September 2002. Interstitial fluid pressure measurements were made before radiation therapy (pre-radiation therapy interstitial fluid pressure) and after a median of 28.8 Gy in 16 fractions (range, 25.2-30.6 Gy in 14-17 fractions) of radiation therapy (mid-radiation therapy interstitial fluid pressure), using a modified wick-in-needle technique. Median follow-up was 74 months (range, 2-118 months). The Kaplan-Meier method with the log-rank test and Cox's proportional hazard model were used in univariate and multivariate analyses, respectively, of prognostic factors for recurrence-free survival. Median pre-radiation therapy and mid-radiation therapy interstitial fluid pressure were 29.0 mm Hg (range, 4.0-93.9 mm Hg) and 20.0 mm Hg (range, -1.2 to 29.6 mm Hg), respectively (P = 0.001). Pre-radiation therapy interstitial fluid pressure was significantly higher in adenocarcinomas than squamous cell carcinomas (P = 0.028). Significant reduction of interstitial fluid pressure was noted only in patients with complete responses (P = 0.002), and mid-radiation therapy interstitial fluid pressure was significantly lower in patients with complete responses (P = 0.036). In the multivariate analysis including interstitial fluid pressures and clinical variables, pre-radiation therapy interstitial fluid pressure was an independent prognostic factor for local and distant recurrence-free survival (P = 0.001 and 0.027, respectively). Mid-radiation therapy interstitial fluid pressure measurement may be useful in predicting radiation therapy responses, and pre-radiation therapy interstitial fluid pressure was a significant prognostic factor for local and distant relapse-free survival in patients with cervical cancer after radiation therapy.

From intravitreal cell‐encoated drug therapy to low‐(brain‐)pressure‐glaucoma

Abstract Purpose To present potentially new developments in the intraocular drug delivery for therapy of retinal diseases as well as new development for the discussion of the pathogenesis of glaucomatous optic neuropathy. Methods The advantages and limitations of the current intraocular drug therapy will partially be discussed. Additionally, morphologic findings of the optic nerve head assessment inglaucoma and of measurements of the lumbar cerebrospinal fluid pressure (CSF‐P) will be presented. Results Analysis of morphologic differenecs between glaucomatous versus non‐glaucomatous optic nerve damage suggests that high‐pressure glaucoma and normal‐pressure glaucoma may share some aspects in their pathogenesis. Correspondingly, the CSF‐P data suggest that normal‐pressure glaucoma may be associated with a low brain pressure. Experimental studies omn the intraocular cell‐based drug delivery suggests that these cells survive for several weeks int he viotreous cavity and continously produce substances, e.g. glucagon‐like peptide 1 and endostatin. Conclusion The prelimanry data suggest that intraocular cell‐based therapy is potentially useful for the treatment of intraocular diseases. Addtiionally, the CSF‐P meausrements suggest that a low brain pressure may potentially be connected with glaucomatous optic neuropathy. Commercial interest

The Neuro-Ophthalmology Research Disease Investigator Consortium (NORDIC)

The Neuro-Ophthalmology Research Disease Investigator Consortium (NORDIC)

The effects of carbon dioxide on measuring cerebral spinal fluid pressure

The effects of pCO2 on cerebral spinal fluid (CSF) pressure measurement were observed in four patients. Children presenting with either a diagnosis or suspected diagnosis of IIH, who were undergoing lumbar puncture under a general anaesthetic for pressure measurement, were recruited to study the relationship between pCO2 and CSF pressure measurements. A rise of end-tidal pCO2 by 1 kPa causes a rise of CSF pressure by 3.5-12 cm H20. Controlling of pCO2 is important when measuring CSF pressure to prevent misdiagnosis and over treatment of patients with idiopathic intracranial hypertension (IIH).

Effects of Drafting on Hydrodynamic and Metabolic Responses in Front Crawl Swimming

Effects of drafting on the hydrodynamic and metabolic responses of the drafter behind and at the side of a passive and an active lead swimmer were related to the influence of a lead swimmer on the flow field of the draftee. Passive drag of the draft swimmer was compared for the nondrafting condition, in the drafting conditions behind a passive and an active lead swimmer, and at the side of a passive and an active lead swimmer. The effect was also evaluated with oxygen uptake measurements. Fluid pressure measurements were made behind and at the side of a passive and an active lead swimmer to examine the flow field. Behind a passive lead swimmer, passive drag was significantly reduced by 20%, and behind an active lead swimmer, it was reduced by 9%. At the side of a passive lead swimmer, passive drag was significantly increased by 9%, and at the side of an active lead swimmer, it increased by 8%. Oxygen uptake was significantly reduced by 25% behind a passive lead swimmer, by 11% behind an active lead swimmer, and only marginally changed at the side of a lead swimmer. The pressure measurements indicated a 33% decrease in mean flow velocity behind an active lead swimmer but an increase in peak flow velocities due to the kick of the lead swimmer. These increases could explain the lesser decrease in passive drag behind an active versus a passive lead swimmer. The best position for a draft swimmer was found to be directly behind an active lead swimmer at a distance of 0.50 m between the toes of lead swimmer and the hands of drafter, with significant reductions in both passive drag and oxygen uptake when drafting.

Real Time Measuring of the Pressure Drops against Changing the Fluid Velocity on the Critical Points of the Fluid System

The purpose of this article is to measure fluid pressure drops against the changing velocity on the critical points of the fluid system by using mechatronics equipments and techniques. Critical points of the fluid system to be measured pressure drops are gate valve, globe valve, flow control valve, sudden enlargement, 45 or 90 junctions etc. Pressure drops occurs mentioned areas much more than other parts of fluid system. Pressure drop is directly concerning with flow rate of fluid. It was used venture-meter and orifice-plate to measure flow rate and fluid velocity in pipe. Pressure transmitters were used to measure pressure drops on the critical points of fluid system in according to changing flow rate of fluid. Pressure transmitters produce analog signals between 4-20 mA in according to changing pressure of fluid in pipe and analog input signals are interpreted through an A/D device, and is originate from pressure sensors. All the received data from pressure transmitters are transferred to computer via A/D cards. Received data from pressure transmitters is evaluated by using developed program to measure fluid friction losses with changing pressure differences and flow rate, velocity of fluid, Reynolds number, fluid type and some values can be seen on the screen of computer in real time.

New Downhole-Fluid-Analysis Tool for Improved Reservoir Characterization

Summary Downhole fluid analysis (DFA) has emerged as a key technique for characterizing the distribution of reservoir-fluid properties and determining zonal connectivity across the reservoir. Information from profiling the reservoir fluids enables sealing barriers to be proved and compositional grading to be quantified; this information cannot be obtained from conventional wireline logs. The DFA technique has been based largely on optical spectroscopy, which can provide estimates of filtrate contamination, gas/oil ratio (GOR), pH of formation water, and a hydrocarbon composition in four groups: methane (C1), ethane to pentane (C2–5), hexane and heavier hydrocarbons (C6+), and carbon dioxide (CO2). For single-phase assurance, it is possible to detect gas liberation (bubblepoint) or liquid dropout (dewpoint) while pumping reservoir fluid to the wellbore, before filling a sample bottle. In this paper, a new DFA tool is introduced that substantially increases the accuracy of these measurements. The tool uses a grating spectrometer in combination with a filter-array spectrometer. The range of compositional information is extended from four groups to five groups: C1, ethane (C2), propane to pentane (C3–5), C6+, and CO2. These spectrometers, together with improved compositional algorithms, now make possible a quantitative analysis of reservoir fluid with greater accuracy and repeatability. This accuracy enables comparison of fluid properties between wells for the first time, thus extending the application of fluid profiling from a single-well to a multiwall basis. Field-based fluid characterization is now possible. In addition, a new measurement is introduced—in-situ density of reservoir fluid. Measuring this property downhole at reservoir conditions of pressure and temperature provides important advantages over surface measurements. The density sensor is combined in a package that includes the optical spectrometers and measurements of fluid resistivity, pressure, temperature, and fluorescence that all play a vital role in determining the exact nature of the reservoir fluid. Extensive tests at a pressure/volume/temperature (PVT) laboratory are presented to illustrate sensor response in a large number of live-fluid samples. These tests of known fluid compositions were conducted under pressurized and heated conditions to simulate reservoir conditions. In addition, several field examples are presented to illustrate applicability in different environments.