Resumption Of Flow Research Articles

Upper limb artery segmental occlusions due to chronic use of ergotamine combined with itraconazole, treated by thrombolysis

BackgroundThe ergotamine tartrate associated with certain categories of drugs can lead to critical ischemia of the extremities. Discontinuation of taking ergotamine is usually sufficient for the total regression of ischemia, but in some cases it could be necessary thrombolytic and anticoagulant therapy to avoid amputation.Case reportA woman of 62 years presented with a severe pain left forearm appeared 10 days ago, with a worsening trend. The same symptoms appeared after 5 days also in the right forearm. Physical examination showed the right arm slightly hypothermic, with radial reduced pulse in presence of reduced sensitivity. The left arm was frankly hypothermic, pulse less on radial and with an ulnar humeral reduced pulse, associated to a decreased sensitivity and motility.Clinical history shows a chronic headache for which the patient took a daily basis for years Cafergot suppository (equivalent to 3.2 mg of ergotamine).From about ten days had begun therapy with itraconazole for vaginal candidiasis. The Color-Doppler ultrasound shown arterial thrombosis of the upper limbs (humeral and radial bilateral), with minimal residual flow to the right and no signal on the humeral and radial left artery.ResultsAngiography revealed progressive reduction in size of the axillary artery and right humeral artery stenosis with right segmental occlusions and multiple hypertrophic collateral circulations at the elbow joint. At the level of the right forearm was recognizable only the radial artery, decreased in size. Does not recognize the ulnar, interosseous artery was thin. To the left showed progressive reduction in size of the distal subclavian and humeral artery, determined by multiple segmental steno-occlusion with collateral vessels serving only a thin hypotrophic interosseous artery.Arteriographic findings were compatible with systemic drug-induced disease. The immediate implementation of thrombolysis, continued for 26 hours, with heparin in continuous intravenous infusion and subsequent anticoagulant therapy allowed the gradual disappearance of the symptoms with the reappearance of peripheral pulses.ConclusionAngiography showed regression of vasospasm and the resumption of flow in distal vessels. The patient had regained sensitivity and motility in the upper limbs and bilaterally radial and ulnar were present.

Assessing water stress in Mediterranean lotic systems: insights from an artificially intermittent river in Greece

Water stress in Mediterranean countries is the result of both variable and changing climatic conditions and widespread anthropogenic pressures. Evrotas, an intermittent river located in Southern Greece, was used as a case study to assess the impacts of water stress on Mediterranean lotic ecosystems. Based on hydrological analyses, it was revealed that during prolonged drought years, such as the summers of 2007 and 2008, the vast majority of the Evrotas riverbed was completely desiccated, primarily as a result of substantial water abstraction for irrigation. The effects of desiccation on the riverine ecosystem were evaluated using fish and macroinvertebrate assemblages according to the demands of the Water Framework Directive 2000/60/EC (WFD). Faunal responses to water stress were assessed through comparisons of assemblages attributes in perennial and intermittent reaches and pre-drought versus post-drought communities. Effects of hydrological disturbance on fish species richness, density, percentage composition and size structure were more pronounced in intermittent than in perennial sites. The most obvious and immediate impact was the elimination of populations in the intermittent reaches. However, upon flow resumption, the recolonisation from upstream perennial reaches began, thereby permitting partial re-establishment of the depleted fish communities. Nevertheless, the structural integrity of fish communities remained severely impacted and recovery was markedly slow. On the contrary, post-drought macroinvertebrate assemblages were not affected by summer droughts, and the recruitment processes were rapid after flow resumption. Our findings point to the necessity of establishing a distinction between naturally and artificially driven intermittent rivers. We, therefore, propose the introduction of an “artificially intermittent Mediterranean river” condition within the context of the WFD assessment applications.

Capital Flows and Financial Stability: Monetary Policy and Macroprudential Responses

The resumption of capital flows to emerging market economies since mid 2009 has posed two sets of interrelated challenges for policymakers: (i) to prevent capital flows from exacerbating overheating pressures and consequent inflation, and (ii) to minimize the risk that prolonged periods of easy financing conditions will undermine financial stability. While conventional monetary policy maintains its role in counteracting the former, there are doubts that it is sufficient to guard against the risks of financial instability. In this context, there have been increased calls for the development of macroprudential measures, with an explicit focus on systemwide financial risks. Against this background, this paper analyses the interplay between monetary policy and macroprudential regulations in an open economy DSGE model with nominal and real frictions. The key result is that macroprudential measures can usefully complement monetary policy. Even under the optimal policy, which calls for a rather aggressive monetary policy reaction to inflation, introducing macroprudential measures is found to be welfare improving. Broad macroprudential measures are shown to be more effective than those that discriminate against foreign liabilities (prudential capital controls). However, these measures are not a substitute for an appropriate moneraty policy reaction. Moreover, macroprudential measures are less useful in helping economic stability under a technology shock.

Does G-4 Liquidity Spill Over?

The resumption of strong capital flows into emerging markets in mid-2009 brought back the debate over whether pull or push factors are the main determinants. This paper, using panel specifications with alternative measures of global liquidity, asks the question whether G-4 liquidity expansion spills over to the rest of the world. The paper finds strong positive links between G-4 liquidity expansion and asset prices, such as equities, in the liquidity receiving economies, which indicates that the push factor plays an important role in asset prices. Liquidity also has a strong positive link with the accumulation of official reserves and with equity portfolio inflows in receiving economies. Moreover, the association between excess equity returns, excess credit growth, and global liquidity has implications for rising risks to financial stability in the receiving economies.

A Dynamic Simulation Study of Water Hammer for Offshore Injection Wells To Provide Operation Guidelines

Summary In water injectors, rapid shut-in creates a water hammer. Water-hammer effects resulting from the shutting in of water-injection wells have a considerable impact on injection-well performance and longevity. Over time, injectors that undergo repeated rapid shut-ins often have significantly reduced injectivity and show evidence of sanding and even failure of the downhole completion. This study seeks to provide an operational reference for the well-injection operation and valve installation to mitigate backflow and maintain the downhole- sand-control-device integrity and thus good water injectivity. Two different shut-in scenarios for an offshore injection system have been investigated. One of the scenarios is that two wells are shut in and the third well is kept open. The other scenario is that the topside pump is stopped while the injection wells are still kept open. Water-hammer sensitivity on different parameters, such as valve-installation position, stroke time, water-backflow conditions, and the hydraulic characteristics, has been performed. For Scenario I, the pressure change because of the wellhead shut-in is approximately 200 psi at bottomhole, which is much lower than the amplitude seen at the wellhead (3,400 psi). The third well, which stays open for injection, experiences an even larger pressure surge (approximately 450 psi at bottomhole). Backflow for the opening well could be close to 10,000 STB/D. With increasing skin because of cumulative injectivity damage by water-particle plugging and thermal-induced fracture closure at shut-in, the water-hammer-pressure fluctuation can be as high as 1,200 psi. For Scenario II, pressure fluctuation because of topside shut-in is 300 psi. With the surface-controlled subsurface safety valve (SCSSV) closing when backflow is felt, the water-hammer fluctuation can be reduced to 200 psi. Unlike the classic water hammer in pipelines, water hammer in injection wells is much less in surge amplitude because the high-injectivity reservoir behaves like a cushion to absorb the water-hammer impact on the downhole completion and sandcontrol infrastructure. Water hammer in the wells and pipeline system experiences (1) after-flow with reduced bottomhole pressure (BHP) and flow rate into formation, (2) backflow when BHP becomes less than reservoir pressure, and (3) resumption of water flow into reservoir when BHP starts to increase. This cyclic process continues with reduced amplitude in each cycle because of friction. A check valve set at the bottomhole could stop the backflow in less than 1 second. This study provides useful reference and operation guidelines on offshore water-injection and completion design consideration.

Test of three methods to detect the overbank flow from water level time‐series analysis

AbstractIn this study, we propose to identify morphological and hydraulic characteristics related to overbank flows in the water level time‐series available at many gauged stations. The results obtained at 13 river stations (the catchment sizes vary from 10 to 1700 km2 with contrasted geology, land use and rainfalls regime) show that overflow mechanisms at the river‐reach scale can be systematically identified in the water level frequency distribution estimated with the peaks‐over‐threshold (POT) method. A first level (Lts1) was in the range of the incipient flooding onto the floodplain. Even if the definition of this level is variable in terms of flooded area at the reach scale, this method can be useful in providing a first estimation of the bankfull level for many gauged stations, without complex and costly field surveys. A second level (Lts2) was systematically detected on average 38 cm above the topographic flat floodplain elevation. The Lts2 inflection in the water‐level frequency distribution is assumed to reflect a composite effect of catchment hydrology and local hydraulics and channel geometry, without possibility to make a clear distinction between both processes at the moment. The local or reach scale effect would probably play an essential role in the frequency distribution as flood attenuation at catchment scale may explain the inflection Lts2 at only three sites. In light of the knowledge acquired in laboratory flumes with compound channels, most of the time Lts2 level would correspond to the level of resumption of flow both in the main channel and the floodplain. Once this method is validated in various physiographic contexts, it should apply to many hydrometric stations for both synchronic (e.g. regional analysis) and diachronic analysis (e.g. evolution over time of the bankfull discharge) to evaluate anthropic impacts on river morphology. Copyright © 2010 John Wiley & Sons, Ltd.

Mobilization of metals and phosphorus from intact forest soil cores by dissolved inorganic carbon

Increased dissolved inorganic carbon (DIC) enhances the mobilization of metals and nutrients in soil solutions. Our objective was to investigate the mobilization of Al, Ca, Fe, and P in forest soils due to fluctuating DIC concentrations. Intact soil cores were taken from the O and B horizons at the Bear Brook Watershed in Maine (BBWM) to conduct soil column transport experiments. Solutions with DIC concentrations (∼20-600 ppm) were introduced into the columns. DIC was reversibly sorbed and its migration was retarded by a factor of 1.2 to 2.1 compared to the conservative sodium bromide tracer, corresponding to a log K (D) = -0.82 to -0.07. Elevated DIC significantly enhanced the mobilization of all Al, Fe, Ca, and P. Particulate (>0.4 μm) Al and Fe were mobilized during chemical and flow transitions, such as increasing DIC and dissolved organic carbon (DOC), and resumption of flow after draining the columns. Calcium and P were primarily in dissolved forms. Mechanisms such as ion exchange (Al, Fe, Ca), ligand- and proton-promoted dissolution (Al and Fe), and ligand exchange (P) were the likely chemical mechanisms for the mobilization of these species. One column was packed with dried and sieved B-horizon soil. The effluent from this column had DOC, Al, and Fe concentrations considerably higher than those in the intact columns, suggesting that these species were mobilized from soil's microporous structure that was otherwise not exposed to the advective flow. Calcium and P concentrations, however, were similar to those in the intact columns, suggesting that these elements were less occluded in soil particles.

Mechanism of Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation: Which Anti-A/Anti-B Antibodies are Responsible, Natural or de Novo?

Mechanism of Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation: Which Anti-A/Anti-B Antibodies are Responsible, Natural or de Novo?

Organic matter availability structures microbial biomass and activity in a Mediterranean stream

Summary1. We compared microbial biomass (bacteria, fungi, algae) and the activity of extracellular enzymes used in the decomposition of organic matter (OM) among different benthic substrata (leaves, coarse and fine substrata) over one hydrological year in a Mediterranean stream.2. Microbial heterotrophic biomass (bacteria plus fungi) was generally higher than autotrophic biomass (algae), except during short periods of high light availability in the spring and winter. During these periods, sources of OM shifted towards autochthonous sources derived mainly from algae, which was demonstrated by high algal biomass and peptidase activity in benthic communities.3. Heterotrophic activity peaked in the autumn. Bacterial and fungal biomass increased with the decomposition of cellulose and hemicellulose compounds from leaf material. Later, lignin decomposition was stimulated in fine (sand, gravel) and coarse (rocks, boulders and cobbles) substrata by the accumulation of fine detritus.4. The Mediterranean summer drought provoked an earlier leaf fall. The resumption of the water flow caused the weathering of riparian soils and subsequently a large increase in dissolved organic carbon and nitrate, which led to growth of bacteria and fungi.

Impacts of climatic stability on the structural and functional aspects of macroinvertebrate communities after severe drought

Summary1. Unpredictable, extreme climatic events (e.g. droughts) can potentially destabilize aquatic communities. From 1998 to 2002, southwestern Georgia, U.S.A., experienced the third worst drought of the last 100 years, leading to loss of surface flow in many small streams. We sampled macroinvertebrates, flow and water chemistry in small headwater streams from 2001 to 2007 in two adjacent coastal plain streams of contrasting headwater type (wetland and groundwater‐fed seep) following resumption of flow.2. Decreasing water temperature, conductivity and nutrient concentrations within the first 2 years of the study indicated flushing of the streambed associated with increased discharge. Invertebrate community composition became less variable over time and during wetter years, reflecting water chemistry, hydrological and climate conditions.3. A core set of species appeared immediately following breaking of the drought in both streams, reflecting a shared species pool. These species exhibited resilience traits, including short life cycles and resistance to desiccation, which allowed for rapid recovery from disturbance. Such species, which were small‐bodied, sclerotized and abundant in the drift, were then replaced as flows increased by those that were larger, soft‐bodied and rare in drift, suggesting a more stable and less ephemeral habitat.4. Hydrologic regime and long‐term precipitation indices were strongly correlated with invertebrate community and trait structure. Long‐term data allowed for better interpretation of the effects of infrequent disturbances on aquatic ecosystems. Additionally, long‐term precipitation indices (i.e. 48‐month standardized precipitation index) can indicate the likelihood of a return to drought, allowing for the collection of pre‐disturbance data.

Effect of nadcin on energy supply system and apoptosis in ischemia-reperfusion injury to the myocardium

Nadcin in a dose of 90 mg/kg administered to dogs with subacute stage of ischemia-reperfusion myocardial injury immediately after blood flow resumption normalized redox potential of cardiomyocytes and mitochondria and restored the total content of adenyl and pyridine nucleotides. The decrease in the synthesis of ATP and pyridine nucleotides and reduction of the redox potential of the energy supply system were inversely related to the increase in poly-(ADP-ribose)-polymerase activity in the ischemic area and nonischemic region. Nadcin abolished the increase in poly-(ADP-ribose)-polymerase activity in the ischemic area of the right ventricle, nonischemic region, and ischemic area of the left ventricle (by 2.4, 2.9, and 1.52 times, respectively) and normalized bioenergetic activity of cardiomyocytes during ischemia-reperfusion myocardial injury.

Relationships between Force-Time Parameters and Muscle Oxygenation Kinetics during Maximal Sustained Isometric Grip and Maximal Repeated Rhythmic Grip with Different Contraction Frequencies

The purposes of this study were to examine the relationships between various force-time parameters and muscle oxygenation kinetics during maximal sustained isometric grip (SIG) and maximal repeated rhythmic grips (RRG) with different grip intervals (interval times: 5, 4, 3, and 2 s). Subjects were 10 healthy young males, aged 20-26 years (height 173.9+/-7.3 cm, body mass 71.5+/-11.2 kg). After measuring maximal grip force, each subject performed the SIG and RRG tests with a target frequency of 12, 15, 20, and 30 grips.min(-1) (interval times: 5, 4, 3, and 2 s, respectively) for 6 min. The decreasing time until 80% MVC showed significant and high correlations with final force values in RRGs with over 3 s intervals (r=0.866-0.941), but not in the SIG and RRG with a 2 s interval. The time at the lowest Oxy-Hb/Mb value showed a significant and high correlation with the time at the highest Deoxy-Hb/Mb value only in the SIG and RRG with a 2 s interval (r=0.825-0.916). Oxy-Hb/Mb decreases markedly and deoxy-Hb/Mb increases after the onset of SIG due to the obstruction of blood flow caused by the increase in intramuscular pressure. A similar physiological response to that of SIG occurs also in RRG with a 2 s interval, but RRGs with intervals over 3 s achieve more resumption of blood flow in the muscular relaxation phase. Hence, in spite of the same RRGs, it was determined that RRGs with intervals over 3 s differ significantly in a changing pattern of grip force and muscle oxygen kinetics from RRGs with a 2 s interval.

Phytoplankton production and nutrient distributions in a subtropical estuary: Importance of freshwater flow

The relationships between phytoplankton productivity, nutrient distributions, and freshwater flow were examined in a seasonal study conducted in Escambia Bay, Florida, USA, located in the northeastern Gulf of Mexico. Five sites oriented along the salinity gradient were sampled 24 times over the 28-mo period from 1999 to 2001. Water column profiles of temperature and salinity were measured along with surface chlorophyll and surface inorganic nutrient concentrations. Primary productivity was measured at 2 sites on 11 dates, and estimated for the remaining dates and sites using an empirical regression model relating phytoplankton net production to the product of chlorophyll, euphotic zone depth, and daily solar insolation. Freshwater flow into the system varied markedly over the study period with record low flow during 2000, a flood event in March 2001, and subsequent resumption of normal flow. Flushing times ranged from 1 d during the flood to 20 d during the drought. Freshwater input strongly affected surface salinity distributions, nutrient flux, chlorophyll, and primary productivity. The flood caused high turbidity and rapid flushing, severely reducing phytoplankton production and biomass accumulation. Following the flood, phytoplankton biomass and productivity sharply increased. Analysis of nutrient distributions suggested Escambia Bay phytoplankton alternated between phosphorus limitation during normal flow and nitrogen limitation during low flow periods. This study found that Escambia Bay is a moderately productive estuary, with an average annual integrated phytoplankton production rate of 290 g C m−2 yr−1.

Physico‐chemical and biological controls on dissolved organic matter in peat aggregate columns

SummaryWe investigated the importance of physico‐chemical mechanisms responsible for the release of dissolved organic matter (DOM) from a peaty soil. Columns containing peat aggregates (embedded within a sand matrix) provided an experimental system in which both convective and diffusive processes contributed to DOM leaching. The use of aggregated peat avoided the problems associated with traditional batch equilibration experiments in which soil structure is destroyed. Biotic and abiotic processes operating in the columns were manipulated by working with two unsterilized columns (at 5°C and 22°C) and one gamma irradiation‐sterilized column (5°C). Continuous solute flows (< 80 hours) and periods of flow interruption (five interruptions of 6 hours to 384 hours) were applied to the columns (using a 1‐mm NaCl electrolyte) to investigate mechanisms of diffusion‐controlled release of DOM. For all columns, dissolved organic carbon and nitrogen (DOC and DON) effluent concentrations increased after resumption of flow and the maximum concentrations increased with increased flow‐interruption duration. Measurements of effluent UV absorbance (λ= 285 nm) showed that the DOM leached immediately after the flow interruptions contained fewer aromatic moieties of lower molecular weight than the DOM leached after periods of steady flow. The sterilized column had larger DOC and DON effluent concentration spikes than those from the unsterilized column at 5°C (38 mg C dm−3 and 6.5 mg N dm−3 versus 13 mg C dm−3 and 6.5 mg N dm−3 after the 384 hours flow interruption). This result suggested that the concentrations of DOM resulting from physico‐chemical release mechanisms (sterilized column) were attenuated by biological activity (unsterilized columns). Our results indicate that the peat’s microporous structure provides reservoirs of DOM that interact with solute in transport pores via abiotic, rate‐controlled mass transport. Hence, diffusion can influence the quantity and composition of DOM leached from peat in the field depending on intensity and duration of rainfall.

Leader/return‐stroke‐like processes in the initial stage of rocket‐triggered lightning

Linear streak film, video, current, and electric field records from nine triggered‐lightning flashes are analyzed to examine the process of cutoff and reestablishment of current during the initial stage of rocket‐triggered lightning. All of the data were acquired at the International Center for Lightning Research and Testing at Camp Blanding, Florida, in 2002 and 2003. It is shown that in some rocket‐triggered lightning events, the process of current cutoff and reestablishment during the initial stage is similar to a leader/return‐stroke sequence, although the currents in this process are typically an order of magnitude smaller (1 kA or so) than those in a triggered or natural lightning subsequent stroke (10–15 kA). The events were separated into two groups based on observed characteristics, with the duration of the current cutoff interval being the primary differentiating characteristic. In some cases, two or three failed attempts at current reestablishment prior to the successful resumption of current flow in the channel were observed. Currents associated with the unsuccessful attempts were typically an order of magnitude smaller (100 A or so) than in the process which finally reestablished the current.

Intermittent capillary perfusion in rat pancreas grafts following short- and long-term preservation in University of Wisconsin solution

In pancreas transplantation (PTx), ischemia/reperfusion-induced deterioration of graft-microcirculation is accompanied by alterations of intermittent capillary perfusion (IP; alternating cessation and resumption of capillary blood flow) is known to counteract malperfusion. Incidence and effectiveness of IP following short- versus long-term preservation of pancreas grafts with University of Wisconsin (UW) solution has not been examined so far. PTx was performed in Lewis rats following 2-h or 18-h preservation in UW solution. Using intravital fluorescence microscopy, functional capillary density (FCD), red blood cell (RBC) velocity, IP-incidence and -frequency were analyzed. Laser Doppler flowmetry allowed for the determination of erythrocyte flux and velocity. Measurements were performed at 30, 60 and 120 min after reperfusion. Nontransplanted animals served as controls. FCD, RBC-velocity and -flux remained unchanged in the 2-h group. IP was encountered in 87% of all observation areas at 120 min. After 18-h ischemia, FCD was significantly reduced, which was paralleled by a 50% incidence of IP at 120 min. Tissue edema and leukocyte infiltration in pancreas grafts following 18-h preservation were significantly enhanced. Therefore, IP is an important mechanism aimed at improving microcirculation and UW solution is suitable to preserve vasomotion-activities enabling long-term preservation in a pancreas graft.

Méthodes d'urodynamique non invasive chez l'homme

Purpose Pressure-flow studies are currently recognized as the criterion standard to quantify urethral obstruction and its consequence on detrusor contractility. These tests have some disadvantages: they are invasive, time-consuming and expensive and entail risk of disease for the patient. Less invasive methods have been proposed to give the same results without the disadvantages. In this study, we conducted a critical analysis of the devices and techniques and their results. Method After a brief reminder of the general behavior of the flow in an obstructed urethra, we describe the main non-invasive techniques: penile urethral compression-release (PCR), cuffs, and condoms. Using the VBN ® method, we tried to quantify data from these techniques to specify the relation with the usual parameters of bladder outlet obstruction. Results In the absence of brisk change of the flow rate, the voiding phases are easily analyzed. With minor corrections, recorded external or cuff pressures could be used in the ICS nomogram; unfortunately, these pressures are greatly modified by perturbations of the nervous control. The spike of flow (due to urine storage in the urethra) observed at resumption of flow after each interruption presents mathematical difficulties for quantitative and reliable modeling but could give a consistent empirical interpretation. Conclusion Of the reported non-invasive tests, all except PCR have an important instrumental heaviness and induce strong perturbations of the nervous control. If they cannot allow an accurate quantification of urethral obstruction and detrusor contractility, they could allow for classification of benign prostatic hypertrophy (BPH) patients. Despite the mathematical problems set by the theory of spikes, the empirical use of the spikes amplitude could perhaps be clinically useful.

Early Acid–Base Balance Disorders During Kidney Transplantation

Introduction Reperfusion is a crucial moment in kidney transplantation. Resumption of blood flow is associated with many metabolic changes, which result from the kidney’s initial condition and preservation. These biochemical alterations including the acid–base balance are the part of ischemia–reperfusion injury. The study’s purpose was to examine acid–base balance during the first 30 minutes after reperfusion of the transplanted kidney. Materials and Methods The 30 recipients (13 men, 17 women) averaged ages of 46 ± 14 years. Measurements performed nine times (at 0, 1, 3, 5, 10, 15, 20, 25, and 30 minutes after unclamping renal vessels) included: gas analysis, expiratory P co 2, tidal volume, and respiratory rate. The evaluation of the temporary acid–base balance was performed on the basis of common parameters: pH, P co 2, [HCO 3 −], and base excess (BE). The patients were under general anesthesia with stable external conditions of O 2 saturation, heart rate, blood pressure, and temperature. Blood samples were analyzed using Corning 278 and 248 blood gas analyzer; vital parameters were recorded using Ohmeda 5250 RGM and Dräger Sulla 909V/Julian apparatus. Results The analysis showed increasing metabolic acidosis with coexisting increase in blood P co 2, changes that were most intense in the first minute of reperfusion. Decreasing mean pH index did not exceed physiologic limits, but the final mean values of [HCO 3 −] and BE were in most of cases below the limit. Increased expiratory air P co 2 was most intense in the first 3 minutes reaching a maximum at about 15 minutes. Conclusions The beginning of reperfusion was the cause of increasing metabolic acidosis, which was partially compensated by blood buffers. Simultaneous increase in expiratory P co 2, corresponding to the dynamics of acidosis, indicated the existence of respiratory compensation. Sudden increase in acidosis parameters may be the result of lactate accumulation during kidney ischemia. The decreased [HCO 3 −] may indicate postreperfusion kidney injury, which must be the subject of further research.

Right varicocele and hypoxia, crucial factors in male infertility: fluid mechanics analysis of the impaired testicular drainage system

Varicocele is considered a predominantly unilateral left-sided disease. However, since male fertility is preserved with only one healthy testis, infertility perforce represents bilateral testicular dysfunction. It was hypothesized that: (i) right varicocele cannot be diagnosed by palpation and therefore has not been treated in the past by the traditional treatment, and (ii) right varicocele causes impaired oxygen supply in the right testicular microcirculation, leading to germ cell degeneration. This study performed venographies of both right and left internal spermatic veins during the treatment of 840 infertile men with varicocele and analysed the results using tools of fluid mechanics. Histopathology of the right testis revealed stagnation of blood flow and degenerative changes attributed to lack of adequate oxygenation in all testicular cell types. Right varicocele was found in the vast majority of the patients. We found that due to the destruction of one-way valves, pathologic hydrostatic pressure is produced in the testicular venous microcirculatory system about five times higher than normal, exceeding arteriolar pressure. The pressure gradient between the arterioles and venules in the testicular tissue is therefore reversed, leading to persistent hypoxia. Right varicocele, although undetected, is prevalent in infertile men with varicocele, hence only bilateral occlusion of the internal spermatic veins, including the associated bypasses, eliminating the pathologic hydrostatic pressure will lead to resumption of arterial blood flow in the testicular microcirculation.

Iris movement mediates vascular apoptosis during rat pupillary membrane regression

In the course of mammalian lens development, a transient capillary meshwork known as the pupillary membrane (PM) forms, which is located at the pupil area; the PM nourishes the anterior surface of the lens and then regresses to make the optical path clear. Although the involvement of apoptotic process has been reported in the PM regression, the initiating factor remains unknown. We initially found that regression of the PM coincided with the development of iris motility, and iris movement caused cessation and resumption of blood flow within the PM. Therefore, we investigated whether the development of the iris's ability to constrict and dilate functions as an essential signal that induces apoptosis in the PM. Continuous inhibition of iris movement with mydriatic agents from postnatal day 7 to day 12 suppressed apoptosis of the PM and migration of macrophage toward the PM, and resulted in the persistence of PM in rats. The distribution of apoptotic cells in the regressing PM was diffuse and showed no apparent localization. These results indicated that iris movement induced regression of the PM by changing the blood flow within it. This study suggests the importance of the physiological interactions between tissues-in this case, the iris and the PM-as a signal to advance vascular regression during organ development, and defines a novel function of the iris during ocular development in addition to the well-known function, that is, optimization of light transmission into the eye.