Significant Increase In Flow Research Articles

Modeling the impacts of tillage practices on water table depth, drain outflow and nitrogen losses using DRAINMOD

Water pollution by nitrate removed from agricultural systems through subsurface tile drains is a major environmental concern in Ontario. The control and reduction of the loading of chemicals to water bodies requires knowledge on the contribution of agricultural systems to water pollution under different cropping management practices. In this study, DRAINMOD model was implemented to predict the effects of conventional tillage (CT) and no tillage (NT) treatments on water table depth, tile effluent and NO3–N losses through subsurface drainage from a 14ha agricultural field at the Green Belt Farm of Agriculture and Agri-Food Canada in Ottawa, Ontario. During the study period, flow was significantly higher under NT than CT mainly during the snowmelt and spring periods. Total nitrate loss under NT was higher than CT but the difference was not significant during the 4years of study period. The climate change scenario of PRECIS was then applied to assess the effect of tillage practices under future climate change. In the future, the changes in climate will result in a significant increase in flow and nitrate under both NT and CT practices. It was also noted that, in future, NO3–N losses under no till treatment are expected to be significantly higher than those under conventional tillage practices in future.

Chronic heart failure and aging - effects of exercise training on endothelial function and mechanisms of endothelial regeneration: Results from the Leipzig Exercise Intervention in Chronic heart failure and Aging (LEICA) study.

A reduction in number and function of endothelial progenitor cells (EPCs) occurs in both physiologic aging and chronic heart failure (CHF). We assessed whether disease and aging have additive effects on EPCs or whether beneficial effects of exercise training are diminished in old age. We randomized 60 patients with stable CHF and 60 referent controls to a training or a control group. To detect possible aging effects we included subjects below 55 (young) and above 65 years (older). Subjects in the training group exercised four times daily at 60% to 70% of VO2max for four weeks under supervision. At baseline and after the intervention the number and function of EPCs were assessed. As compared with young referent controls, older referent controls showed at baseline a reduced EPC number (young: 190 ± 37 CD34/KDR positive cells/ml blood; older: 131 ± 26 CD34/KDR positive cells/ml blood; p < 0.05) and function (young: 230 ± 41 migrated cells/1000 plated cells; older: 185 ± 28 cells/1000 plated cells; p < 0.05). In young and older CHF patients EPC-number (young: 85 ± 21 CD34/KDR positive cells/ml blood; older: 78 ± 20 CD34/KDR positive cells/ml blood) and EPC-function (young: 113 ± 26 cells/1000 plated cells; older: 120 ± 27 cells/1000 plated cells) were impaired. As a result of exercise training, EPC function improved by 24% in older referent controls (p < 0.05), while it remained unchanged in young training referent controls and controls respectively. In young and older patients with CHF four weeks of exercise training resulted in a significant improvement in EPC numbers and EPC function (young: number +66% function +43%; p < 0.05; older: number +69% function +36%; p < 0.05). These results were accompanied by a significant increase in flow mediated dilatation in the training groups of young/older CHF patients and in older referent controls. Four weeks of exercise training are effective in improving EPC number and EPC function in CHF patients. These training effects were not impaired among older patients, emphasizing the potentials of rehabilitation interventions in a patient group where CHF has a high prevalence.

The springs of the Mt. Accellica (southern Italy)

At the foot of Mt. Accellica, along the rivers Tusciano and Torrente Isca della Serra (near the small town of Acerno), there are two important groups of springs (total discharge: about 900 L/s); the first one includes the springs Ausino, Ausinetto and Avella, the second one the springs Olevano and Nuova Olevano.The recharge area and the groundwater flow towards the springs have been identified using piezometric, hydrochemical and isotopic surveys. In detail the main results achieved are:• all data showed that the springs flow following different pathways from the same aquifer constituted by the dolomitic bedrock of the Acerno plain, buried by detritic-alluvial deposits;• the significant flow increase in the Tusciano river comes from the right bank of the river, opposite of what asserted by previous authors;• the limits of the groundwater basin feeding the spring groups have been outlined with the aid of the groundwater balance, carefully evaluated.

MP15-10 VALSALVA VOIDING DISTINGUISHES SLOW URINARY FLOW CAUSED BY ANTERIOR URETHRAL STRICTURES FROM PROSTATIC OBSTRUCTION

You have accessJournal of UrologyTrauma/Reconstruction: Urethral Reconstruction (including Stricture) I1 Apr 2015MP15-10 VALSALVA VOIDING DISTINGUISHES SLOW URINARY FLOW CAUSED BY ANTERIOR URETHRAL STRICTURES FROM PROSTATIC OBSTRUCTION Rajveer Purohit, Matthew Benedon, Gabriel Mekel, James Weinberger, Johnson Tsui, and Jerry Blaivas Rajveer PurohitRajveer Purohit More articles by this author , Matthew BenedonMatthew Benedon More articles by this author , Gabriel MekelGabriel Mekel More articles by this author , James WeinbergerJames Weinberger More articles by this author , Johnson TsuiJohnson Tsui More articles by this author , and Jerry BlaivasJerry Blaivas More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2015.02.893AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES It is difficult to distinguish decreased uroflow in patients who may have anterior urethral strictures (US) from prostatic obstruction (PO) such as older patients who may have undergone a urethroplasty. We hypothesize that in patients with US, Valsalva Voiding (VV) will significantly increase maximum urinary flow rate (Qmax) and will not do so in patients with PO. METHODS A prospective IRB-approved study of men seen at a tertiary care urology clinic was conducted. Subjects were divided into three groups based on clinical and cystoscopic information: group 1 (US), group 2 (PO), and a control group (group 3) with no obstruction. Each subject voided twice without intervention; once with NVV and once with VV. Qmax, voided volume, and PVR were recorded. Patients with voided volumes less than 150ml on either VV or NVV were excluded. In each patient, the difference in Qmax between VV and NVV was compared. In addition, the Siroky nomogram was used to compare normalized bladder volumes with a difference of greater than 1 standard deviation considered a significant increase in flow. A student T-test was used to assess statistical difference. RESULTS 113 individuals were evaluated. 26 were excluded due to voided volume < 150 ml. Mean age was 54 years (range 23–83). Table 1 depicts changes in Qmax between VV & NVV for each group. P values compare differences between VV and NVV. CONCLUSIONS These data suggest that change in Qmax with VV is a useful non-invasive test to distinguish PO from US. Patients with prostatic obstruction do not have any increase in Qmax with VV whereas those with US have slight increases and normal unobstructed individuals have large increases. Change in Qmax between Valsalva Voids and Non-Valsalva Voids Among Each Group Number of Patients Mean Change in Qmax Median Change in Qmax Standard Deviation P-value Urethral Stricture (Group 1) 23 5.04 5 6.75 0.03 Prostatic Obstruction (Group 2) 29 1.66 1 4.79 0.47 Unobstructed (Group 3) 35 7.69 9 8.51 0.01 © 2015 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 193Issue 4SApril 2015Page: e162-e163 Advertisement Copyright & Permissions© 2015 by American Urological Association Education and Research, Inc.MetricsAuthor Information Rajveer Purohit More articles by this author Matthew Benedon More articles by this author Gabriel Mekel More articles by this author James Weinberger More articles by this author Johnson Tsui More articles by this author Jerry Blaivas More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

Segmented whole body haemodynamic responses to a high calorie meal - a novel MR approach

had little effect. Stroke volume and heart rate increases were responsible, with heart rate becoming more dominant over time. There was no significant flow increase to the head, kidneys or legs. Intestinal blood flow (coeliac trunk, SMA, portal vein) was responsible for the increase in cardiac output in the first hour after the meal. The figure shows results from selected multilevel models, adjusted for sex, age and BMI. Aortic flow, stroke volume and heart rate changes compared to rest were significantly different between meal and water ingestions. This was also true for SMA flow but not cerebral, renal or distal aortic flow.

Hemodynamics in Reverse: Paradoxical Increase in Left Ventricular Filling Pressure During the Valsalva Maneuver

(Echocardiography 2014;31:402–405)Key words: Valsalva maneuver, right ventricular function, tricuspid regurgitation, Doppler echocardi-ography, diastolic dysfunctionCase Presentation:A 40-year-old male with a history of arrhythmo-genic right ventricular cardiomyopathy pre-sented for routine evaluation. He reported NewYork Heart Association class IV symptoms. Anechocardiogram (E-9, General Electric, Wauke-sha, WI, USA) showed a severely dilated rightventricle (RV) and right atrium (RA) with sev-erely reduced RV systolic function (Fig. 1A and B;movie clips S1 and S2). The tricuspid valve(TV) annulus was markedly dilated (diame-ter = 58 mm) with wide lack of coaptation of thetricuspid leaflets during systole (Fig. 1A and B;movie clips S1 and S2) resulting in free and lami-nar tricuspid regurgitation (TR) (movie clip S3). Aleftward shift of the interatrial and intraventricu-lar septa was evident, the latter noted in diastole(Fig. 1A; movie clip S1). The inferior vena cava(IVC) was markedly enlarged and noncollapsiblesuggestive of significantly elevated RA pressure(Fig. 1C). Theleftventricle(LV) wasnormal insizewith mildly reduced systolic function (ejectionfraction = 47% by cardiac MRI) (MAGENTOMAvanto, Siemens, Munich, Germany). ColorDoppler, pulse wave (PW) Doppler and colorM-mode showed systolic and diastolic forwardflow across the RV outflow tract (RVOT) and intothemain pulmonaryartery(PA)(Fig. 1D,E,F,andG; movie clip S4). These findings suggested ahigherdiastolic pressure intheRV thanthePAasaresult of severe RV systolic/diastolic dysfunctionand free TR. PW Doppler across the mitral valve(Fig. 2; Table 1) coupled with tissue Dopplerimaging (Table 1) suggested an elevation inleftatrial(LA)pressure.TransmitralDoppleracqui-sition during the strain phase of the Valsalvamaneuver (VM) showed evidence of furtherincrease in LA pressure (Fig. 2). The latter resultedfrom an increase in pulmonary blood flow as evi-denced by a significant increase in flow across theRVOTandPAinducedbytheVM(Fig. 2;Table 1).Discussion:The assessment of filling pressures is an essentialcomponent of any echocardiographic examina-tion regardless whether LV systolic function isimpaired or preserved.

Chronic effects of pulmonary artery stenosis on hemodynamic and structural development of the lungs

Pulmonary artery (PA) stenosis is a difficult obstructive defect to manage since clinicians cannot know a priori which obstructions to treat and when. Prognosis of PA stenosis and its chronic effects on lung development are poorly understood. This study aimed to characterize the hemodynamic and structural effects of PA stenosis during development. Fourteen male Sprague-Dawley rats underwent left PA (LPA) banding at age 21 days, and 13 underwent sham operation. Hemodynamic and structural impacts were studied longitudinally at 20, 36, 52, 100, and 160 days. Chronic LPA banding resulted in a significant reduction in LPA flow (P < 0.0001) and size of both proximal LPA (P < 0.0001) and distal LPA (P < 0.01), as well as a significant increase in flow and size of the right PA (P < 0.05) throughout development. Flows and sizes adapted such that normal levels of wall shear were restored after banding. At 160 days, LPA banding resulted in a significant decrease in left lung volume and an increase in right lung volume but no significant differences in total lung volume. There was an elevation of proximal LPA pressure as well as right ventricular hypertrophy in the banded animals. The banded lung exhibited arterial disorganization, loss of vessels, and enlargement of its bronchial arteries, whereas the contralateral lung showed signs of vascular pathology. There are consequences on development of both lungs in the presence of an LPA stenosis at young age. These results suggest that early intervention may be necessary to optimize left lung growth and minimize right lung vascular pathology.

Rotator Cuff Tendon Blood Flow in a Sheep Model – A Comparison of Single- vs. Double-Row Repairs (SS-19)

Double-row suture anchor repair of rotator cuff tears has been shown to be superior to single-row techniques with regard to footprint reconstruction, load to failure and tendon-to-bone contact pressures. We hypothesized that anchor repair can impair intratendinous blood flow and that the greater contact pressures of double-row techniques would compromise blood flow to a higher degree than single-row repair. The aim of this experimental study was to evaluate the effect of a double-row and a single-row technique on tendon blood flow in a sheep model. 18 sheep underwent detachment and immediate suture anchor repair of the right infraspinatus tendon using either an arthroscopic Mason-Allen suture or a double-row suture-bridge technique. Tendon blood flow was measured using laser Doppler flowmetry before detachment, immediately after repair and 12 weeks thereafter. Six regions of interest were measured, three over the lateral aspect of the footprint and three over the medial aspect. Immediately after repair, tendon blood flow decreased significantly in both repair groups when compared to the native tendons (P= .004). At 12 weeks, a significant increase in flow was observed in both repair groups when compared to the measurements immediately after repair (P= .016). In the single-row group, blood flow decreased by 87.5% after repair, in the double-row group the decrease was 90.6%. The difference between the groups was not statistically significant (P> .05). Subgroup analysis showed that blood flow over the lateral aspect of the footprint decreased by 90% in both groups, whereas over the medial aspect it decreased by 81% in the single-row and by 89% in the double-row group. However, none of these differences were found to be statistically significant. Intratendinous blood flow was significantly compromised immediately after suture anchor repair regardless of the technique used, but appeared to recover within 12 weeks. Since we did not find a significant difference between the two repair groups, our initial hypothesis was rejected.

Impacts of land-use change and best management practice implementation in a Conservation Effects Assessment Project watershed: Northwest Arkansas

A study was conducted to quantify land use and management changes and their effects on water quality as part of an effort to evaluate the effects of best management practices under the Conservation Effects Assessment Project. This study was focused on the Lincoln Lake watershed, a primarily pastured watershed in northwest Arkansas and one of the water- sheds funded under the Conservation Effects Assessment Project competitive grants program. As with a number of other Conservation Effects Assessment Project watersheds, this water- shed has undergone substantial land-use change over the past few years. These changes have occurred concurrently with best management practice implementation. Thus, the need has arisen to determine their impacts on watershed water quality. Land-use analyses covering a 12-year period revealed a rapidly changing landscape, with the various land uses experienc- ing gains and losses at different times. Furthermore, a systematic trend for pastured areas to be replaced by urban land uses was identified, with pastures experiencing a net decline of about 12% during the analyses period. With regard to water quality, downward trends were observed under base and storm flow conditions in the upper reaches (Upper Moores Creek) with significant changes in total phosphorus and total suspended solids (p-values = 0.0153 and 0.0135, respectively). Significant increases in flow and nitrate-nitrogen (p-values = 0.0465 and 0.0927, respectively) were observed in the lower reaches (Lower Moores Creek), while no appreciable changes were observed in one part of the watershed. We conclude that the concurrent implementation of best management practices served to protect water quality from otherwise adverse effects that might have occurred due to a rapid urbanization in the watershed.

625 Pathophysiology of Coronary Blood Flow in Congenital Heart Disease

Background and aims: The effects of CHD on CF are poorly mapped. The aim of this study was to investigate the effects of volume and pressure overload and increased coronary perfusion pressure on coronary flow (CF) in patients with congenital heart disease (CHD).Methods: Posterior descending coronary artery flow was measured using transthoracic Doppler echocardiography in lesions with right ventricular pressure or volume overload: pulmonary valve stenosis (PS) and atrial septal defects (ASD). Left anterior descending coronary artery flow was measured in lesions with left ventricular pressure or volume overload: coarctation of the aorta (CoA) and ventricular septal defect (VSD). The CF data in each patient group were expressed as the percent of the median for healthy controls from the same age group.Results: The CF values were 172% in VSD, 185% in ASD, 233% in PS, and 773% in CoA patients. In CoA patients left ventricular mass (r=0.81, p=0.001), systolic blood pressure (r=0.72, p< 0.0001), diastolic blood pressure (r= 0.77, p< 0.0001), systolic wall tension (r= - 0.77, p=0,004), and signs of inflammation (log CRP, r= - 0.75, p=0.007) correlated with CF.Conclusions: The increase in CF and velocity was most significant in patients with CoA. In newborns, increased coronary perfusion pressure seems to be the most important factor for increased CF, even if the pressure is not assumed to cause a significant increase in flow over the auto-regulatory range of 70-130 mmHg. We also showed that inflammation decreases CF.

Pathophysiology of coronary blood flow in congenital heart disease

ObjectivesThe aim was to investigate the effects of volume and pressure overload and increased coronary perfusion pressure on coronary flow (CF) in congenital heart disease (CHD) patients. BackgroundThe effects of CHD on CF are poorly mapped. MethodsA total of 65 patients with acyanotic CHD and 49 age-matched healthy controls were examined by transthoracic Doppler echocardiography. Posterior descending artery flow was measured in patients with pulmonary valve stenosis (PS) and atrial septal defects (ASDs) i.e. in lesions with right ventricular pressure or volume overload, and left anterior descending artery flow in patients with coarctation of the aorta (CoA) and ventricular septal defect (VSD), in lesions with left ventricular pressure or volume overload. The CF data in each patient group were expressed as the percent of the median for healthy controls from the same age group. ResultsThe CF values were in VSD 172%, ASD 185%, PS 233%, and CoA 773% patients. In CoA patients body surface area (r=0.90, p<0.0001), systolic blood pressure (r=0.72, p<0.0001), diastolic blood pressure (r=0.77, p<0.0001), systolic wall tension (r=−0.77, p=0.004), and signs of inflammation (log CRP, r=−0.75, p=0.007) correlated with CF. ConclusionsThe increase in CF and velocity was most significant in patients with CoA. In newborns, increased coronary perfusion pressure seems to be the most important factor for increased CF, even if the pressure is not assumed to cause a significant increase in flow over the auto-regulatory range of 70–130mmHg. We also showed that inflammation decreases CF.

Longer-term water use of native eucalyptus forest after logging and regeneration: The Coranderrk experiment

The Coranderrk Project, located 70 km east of Melbourne, is Australia’s longest-running paired catchment study. Three small catchments (“Slip Creek”, “Blue Jacket Creek”, and “Picaninny Creek”) originally carrying old growth mountain ash and mixed species have been gauged since 1958. In 1971/72 Picaninny Creek catchment was substantially clear-felled and regenerated, predominantly with mountain ash (Eucalyptus regnans). The annual flow increased for the next 3 years (relative to the control), reaching a peak of almost 300 mm increase relative to the control catchment. Flow then declined; 8 years after the logging the annual flow had returned to pre-logging levels. Annual flow then continued to decline with a maximum reduction of around 200 mm per annum. Thirty-four years after logging the flow was still below the pre-treatment flow and showing no sign of recovery, although there were year to year variations associated with rainfall and drought. In 1972/73 Blue Jacket Creek had a “sawmiller selection” cutting in which approximately 50% of the basal area was removed. The response was a similar but muted version of the Picaninny Creek response. A statistical analysis used 1 year of the pre-treatment period to establish error limits. This showed that in both cases there was a statistically significant increase in flow followed by a statistically significant decrease in flow relative to old growth. Measurement of two of the catchments is continuing.

Transcranial Doppler ultrasound during galvanic labyrinth polarization depicts central vestibular processing, demonstrating bilateral vestibular projection

The combination of galvanic labyrinth polarization and transcranial Doppler ultrasound was employed to depict the neurovascular coupling in the cerebral vestibular areas. For galvanic stimulation, surface electrodes were attached to the right and left mastoid and two further electrodes were fixed near to each shoulder blade. Thus, each pair of electrodes (mastoid to shoulder) facilitated unilateral stimulation of the ipsilateral vestibular labyrinth. Blood flow in the middle cerebral artery and the internal carotid artery in both hemispheres was measured by means of Doppler ultrasound. The transcranial Doppler ultrasound system was head-fixed and allowed continuous monitoring of the blood flow throughout the trials. Using a series of different stimulation modes (bilateral, unilateral left, unilateral right and sham), the changes in mean blood flow velocity were evaluated by comparing baseline blood flow under resting conditions to blood flow during stimulation. A total of 18 trials were performed with each of seven volunteer subjects. Galvanic labyrinth polarization elicited a clear sensation of pendular body movement in all subjects. Significant blood flow increase (P < 0.05) in both hemispheres was observed during bilateral stimulation. Of more interest is that unilateral stimulation also elicited a significant increase in flow in both the ipsilateral and the contralateral hemispheres, demonstrating the existence of bilateral projections from each vestibular labyrinth. The combination of galvanic labyrinth polarization with transcranial Doppler ultrasound blood flow measurement provides a novel approach to the functional assessment of the vestibular system (deep cerebral structures and cortical areas). This novel technique provides a useful tool for clinical examinations.

Distal Revascularization and Interval Ligation (DRIL) Procedure for the Treatment of Ischemic Steal Syndrome after Arm Arteriovenous Fistula

The objective of this study was to investigate the efficacy of the distal-revascularization-interval ligation (DRIL) technique in alleviating symptoms of ischemic steal syndrome and in preserving hemodialysis access. A retrospective chart review was conducted of all patients receiving the DRIL procedure in a 3-year period. There were 38 DRIL bypass grafts identified in 35 patients, with 36 DRILs with follow-up adequate for analysis. Comparison of preoperative and postoperative digital pulse volume recording (PVR) data was made using the t-test. The majority of patients presented with multiple ischemic symptoms, most commonly coolness, pain, and paresthesias. Six patients presented with frank digital necrosis. The mean interval to DRIL was 4.9 months following fistula construction (range 0.1-24). In 66.7% of patients for whom complete follow-up data were available (24/36), all ischemic symptoms were alleviated by DRIL. Of the remaining 12 patients, 11 experienced partial symptom relief. One patient required digital amputation following DRIL. A comparison of pre- and post-DRIL PVRs illustrated a significant increase in these values following DRIL (P < 0.05). DRIL effectively eliminates ischemic symptoms in the majority of patients and produces a significant increase in flow to the ischemic limb. The data support the usage of DRIL as the procedure of choice in the correction of ischemic steal following arm arteriovenous fistula.

Influence of minoxidil on ischemic cutaneous flaps in rats

To evaluate the influence of minoxidil, a well known vasodilator, on ischemic flap necrosis prevention in rats. Ventral cutaneous flaps, measuring 8x4 cm, were designed in 20 Wistar rats based on the right cranial epigastric artery. In the experiment group, 50 mg/kg/day of minoxidil sulfate was administered by orogastric tube and the same amount of saline solution was administered to the control group. Such procedure was initiated 24 h before surgery and kept once a day through the 7th postoperative day. Microcirculation was evaluated with laser fluxometry 24 h before surgical procedure, at immediate postoperative and at the 7th postoperative day. Flap necrosis area was evaluated by 2 methods: planimetry and weight/paper ratio. A significant flow increase in distal and medial extremity at M1 (medial point 1) (p=0.0484) was observed in the experiment group. There was significant difference in flap necrosis prevention in the experiment group (p=0.0433), although after necrosis took place there was no significant difference in necrosis size. (p=0.1051 and p=0.2799). Minoxidil sulfate is effective in avoiding necrosis in ischemic flaps, but after necrosis is present there is no difference in survival area between experimental and control groups.

Does gravity affect functional cerebral blood flow response?

Cerebral blood flow (CBF) is critical for proper neuronal function. Since flow is dependent on perfusion pressure, the cerebrovasculature dilates/constricts in response to driving pressure to maintain flow relatively constant. This process is termed autoregulation and essential to maintaining flow in the upright posture when the effect of gravity results in an 20 mmHg reduction in perfusion pressure to the brain due to the hydrostatic gradient. Up regulation of CBF has been used extensively to localize cognitive activation, i.e. functional imaging. However, due to technical constraints the majority of this work has been done with subjects in the supine position. The recent development of transcranial Doppler (TCD) allows the continuous measurement of cerebral flow velocity (CFV) in the main cerebral arteries. By measuring flow velocity during cognitive tasks, we are able to perform functional TCD. To assess whether gravity had an effect on the functional response to a cognitive task (Trails A & B), we performed functional TCD on subjects in both the upright and supine positions. In addition to cerebral flow velocity in the anterior (ACA) and middle cerebral arteries (MCA) (TCD), we measured beat-by-beat blood pressure (Finapres) and breath-by-breath end tidal CO2 (PETCO2) via nasal cannula (Datex-Ohmeda). Subjects were randomly assigned to either the supine or upright position, performed the task, and then moved to the other position, and performed the same task with different number and letter patterns. Upon going from the supine to upright position, subjects demonstrated a non-significant reduction in both ACA (-44%) and MCA (-32%) flow. In contrast mean arterial pressure increased (817 to 914 mmHg) although non-significant, while PETCO2 did not change (40.81.3 vs 40.01.7 mmHg). During cognitive activation with either the Trails A or B there was a significant increase in flow associated with reductions in cerebrovascular resistance (CVR). Interestingly, this functional activation was attenuated in the upright posture (only significant in the MCA). Surprisingly, the functional activation was also reduced in Trails B compared to Trails A. This was likely the consequence of the hypocapnia that was only present during the Trails B assessment. These data highlight the possibility that functional response to cognitive activation may be affected by body position. Since our healthy control subjects demonstrate an attenuated response, one might postulate that patients with an impaired cerebrovasculature and already attenuated response in the supine position may be at even more risk when upright. Further work is necessary to determine what role perfusion pressure may play in functional cerebral blood flow response and how this attenuated response may impact on functional cognitive performance (See Figure 1).

Human Cerebral Blood Flow and Metabolism in Acute Insulin-Induced Hypoglycemia

How the human brain functions under conditions of acute hypoglycemia remains a complex question by virtue of the potential simultaneous shifts in processes of perfusion, metabolism, and changing demand. We examined this issue by measuring cerebral blood flow (CBF) and oxidative metabolism (CMRO2) in insulin-induced hypoglycemic (HG) and euglycemic (EG) conditions at rest and during motor activation in normal human subjects using magnetic resonance (MR). Experiments were performed on 12 subjects (9M, 3F). The protocol consisted of insulin-induced hypoglycemia (targeting a HG of 60 mg/dL) followed by euglycemia, or in reverse order, each phase lasting approximately 1.5 h. Euglycemia was performed with the same insulin infusion rate so as to match the hypoglycemic phase. Magnetic resonance data were acquired 30 mins after the target plasma glucose was achieved so as to minimize any acute effects. Although the depth of hypoglycemia achieved in the present study was relatively small, the present data found a significant increase in flow in motor cortex with mild hypoglycemia, from 56.4+/-13.6 mL/100 g min (euglycemia) to 64.3+/-7.6 mL/100 g min (hypoglycemia). Using the Renkin-Crone exponential model of oxygen extraction with MR models of susceptibility-based relaxation, analysis of the flow measurements, relaxation and BOLD data also implied that throughout the studies, metabolism and flow remained coupled. Elementary motor task activation was not associated with any consistent larger activated flows. Thus it remains that although mild hypoglycemia induced an increase in basal flow and metabolism, a similar increase was not seen in task activation.

Treatment of Chronic Anal Fissure by Application of l-Arginine Gel: A Phase II Study in 15 Patients

Local application of exogenous nitric oxide donors, such as isosorbide dinitrate and glyceryl trinitrate, promotes fissure healing by reducing anal resting pressure and improving anodermal blood flow. The major drawback of these nitric oxide donors is headache. The overall incidence of this side effect is approximately 40 percent. Recently we have shown in healthy volunteers that L-arginine, being an intrinsic precursor of nitric oxide, reduces anal resting pressure without headache as a side effect. The aim of the present study was to evaluate the effect of L-arginine on anal resting pressure, anodermal blood flow, and fissure healing in patients with chronic anal fissure. Fifteen patients with a chronic anal fissure were included in the present study. Before entering the study 10 patients were unsuccessfully treated by local application of isosorbide dinitrate. Six of these patients experienced severe headache during treatment with isosorbide dinitrate. All patients were treated for at least 12 weeks by local application of a gel containing L-arginine 400 mg/ml five times a day. In patients with a persistent fissure, treatment was continued until 18 weeks. Anal manometry and laser Doppler flowmetry of the anoderm were performed before treatment, 20 minutes after local application of the first dose, and after 12 weeks of treatment. A visual analog scale was used to assess fissure-related pain and headache. One patient dropped out after one day of treatment, and one was excluded because of violation of the study protocol. After 12 weeks of treatment complete fissure healing was observed in 3 of 13 (23 percent) patients, and after 18 weeks the healing rate was 8 of 13 (62 percent) patients. None of the 13 patients experienced typical nitric oxide-induced headache. The pressure recordings showed a significant reduction of maximum anal resting pressure (mean +/- SD): pretreatment 89 +/- 17 mmHg; 20 minutes after application of the first dose 67 +/- 17 mmHg; 12 weeks after treatment 74 +/- 14 mmHg (P < 0.005). Recordings of anodermal blood flow showed a significant increase in flow: pretreatment 0.36 +/- 0.25 volts; 20 minutes after application of the first dose 0.59 +/- 0.27; 12 weeks after treatment 0.64 +/- 0.33 (P < 0.005). Local application of L-arginine promotes fissure healing without headache as a side effect, and L-arginine is effective even in patients not responding to isosorbide dinitrate treatment.

The effect of insulin and sulodexide (Vessel Due F) on diabetic foot syndrome: pilot study in elderly patients

Objective: To assess the efficacy of insulin plus sulodexide (a mixture of 80% heparin-like substances and 20% dermatan sulphate) on diabetic ulcers, and its influence on foot skin microcirculation and diabetic neuropathy. Research design and methods: Two groups of diabetic patients, suffering from severe neuropathy and ulceration, were randomly assigned to insulin (I) plus sulodexide (S) ( n=12) or insulin plus placebo (P) ( n=6) therapy, for 10 weeks. Laser Doppler assessment of foot skin flow (LDF), at rest and 30 or 60 s after arterial occlusion, and nerve conduction tests (sensorial evoked and motoric conduction potentials) have been evaluated in both groups. Results: Postischaemic flow was 2.5 times shorter in ulcerated vs. non-ulcerated feet in diabetic patients. A significant increase in flows after 30 and 60 s ischaemia was detected in both groups at the end of therapy (IS group, ulcerated foot, LDF=60 s: from 99.1±14.3 to 218.6±28.6 PU, P<.001. IP group=from 110.5±13.0 to 164.8±15.4 PU, P<.05). The length of reactive hyperaemia was higher in IS vs. IP group (IS: from 30.3±2.9 to 43.9±2.2 s, P<.001; IP: from 28.7±3.0 to 33.3±3.3 s, ns). Ninety-two percent of ulcers heals in a mean time of 46.4 days (IS group) vs. 83% and 63.0 days, respectively, in IP group. Nerve conduction studies have not demonstrated within- and between-group differences. Conclusions: Sulodexide and insulin improve the postischaemic skin flow in ulcerated feet, without affecting nerve conduction tests. The effect of sulodexide results additive to insulin; it is clinically relevant, in the view of the possibility of reducing the time needed to completely heal ulcers. The ultimate validation of these preliminary results requires extensive trials.

An Alternative Application of Sodium Nitroprusside to Overcome Perioperative Spasm of the Internal Thoracic Artery

Objective: The internal thoracic artery (ITA) is currently the preferred conduit for myocardial revascularization; however, perioperative vasospasm of the internal thoracic artery may cause morbidity. Pedicle preparation and pharmacological vasodilatory treatment vary greatly. This clinical study was performed in order to define the effectiveness of two different applications of sodium nitroprusside as vasodilating agent. Methods: Eighty-six (86) consecutive patients whose left internal thoracic artery was mobilized only by one surgeon for elective coronary artery bypass graft operations were randomly divided into two groups. The internal thoracic artery was allowed to bleed freely, and the flow was determined (flow 1). In group I ( n = 42) 3mg sodium nitroprusside in 10 ml of 5% dextrose solution was sprayed with pressure on the pedicle with a thin 25 gauge needle. In group II ( n = 44) half of the solution was sprayed in the same manner, and the other half of the solution was injected into the pedicle in the periarterial tissue along the length of the pedicle. Free flows of the internal thoracic artery were registered before cardiopulmonary bypass (flow 2) and also just prior to performing internal thoracic artery anastomosis to the left anterior descending artery (flow 3). With each measurement hemodynamic parameters and the time between measurements were recorded. Results: No statistically significant differences were found between the groups in respect to sex ratio, age, body surface area, heart rate 1 and 2, mean arterial pressure 1 and 3. There was no significant difference in the initial flow among groups. Significant differences were noted in the second flow measurement ( P &lt; 0.05) and in the third flow measurement ( P &lt; 0.01) between two groups. For each group there was a significant increase in flow from flow 1 to flow 2 and from flow 2 to flow 3 ( P &lt; 0.02). Conclusion: Sodium nitroprusside injection to the pedicle provides a better flow than simple spraying of the same agent.