Metastable chaos in the ammonia ring laser

We report experimental studies of metastable chaos in the far-infrared ammonia ring: laser. When the laser pump power is switched from above chaos threshold to slightly below, chaotic intensity pulsations continue for a varying time afterward before decaying to either periodic or cw emission. The behavior is in good qualitative agreement with that predicted by the Lorenz equations, previously used to describe this laser. The statistical distribution of the duration of the chaotic transient is measured and shown to be in excellent agreement with the Lorenz equations in showing a modified exponential distribution. We also give a brief numerical analysis and graphical visualization of the Lorenz equations in phase space illustrating the boundary between the metastable chaotic and the stable fixed point basins of attraction. This provides an intuitive understanding of the metastable dynamics of the Lorenz equations and the experimental system.

Assessment of flow in perforating arteries during intracranial aneurysm surgery using intraoperative near-infrared indocyanine green videoangiography

OBJECTIVE: Perforating arteries are commonly involved during the surgical dissection and clipping of intracranial aneurysms. Occlusion of perforating arteries is responsible for ischemic infarction and poor outcome. The goal of this study is to describe the usefulness of near-infrared indocyanine green videoangiography (ICGA) for the intraoperative assessment of blood flow in perforating arteries that are visible in the surgical field during clipping of intracranial aneurysms. In addition, we analyzed the incidence of perforating vessels involved during the aneurysm surgery and the incidence of ischemic infarct caused by compromised small arteries. METHODS: Sixty patients with 64 aneurysms were surgically treated and prospectively included in this study. Intraoperative ICGA was performed using a surgical microscope (Carl Zeiss Co., Oberkochen, Germany) with integrated ICGA technology. The presence and involvement of perforating arteries were analyzed in the microsurgical field during surgical dissection and clip application. Assessment of vascular patency after clipping was also investigated. Only those small arteries that were not visible on preoperative digital subtraction angiography were considered for analysis. RESULTS: The ICGA was able to visualize flow in all patients in whom perforating vessels were found in the microscope field. Among 36 patients whose perforating vessels were visible on ICGA, 11 (30%) presented a close relation between the aneurysm and perforating arteries. In one (9%) of these 11 patients, ICGA showed occlusion of a P1 perforating artery after clip application, which led to immediate correction of the clip confirmed by immediate reestablishment of flow visible with ICGA without clinical consequences. Four patients (6.7%) presented with postoperative perforating artery infarct, three of whom had perforating arteries that were not visible or distant from the aneurysm. CONCLUSION: The involvement of perforating arteries during clip application for aneurysm occlusion is a usual finding. Intraoperative ICGA may provide visual information with regard to the patency of these small vessels.

Ductus venosus Doppler and postnatal outcomes in fetuses with absent or reversed end-diastolic flow in the umbilical arteries

Objective: To evaluate the relationship between ductus venosus Doppler findings on the day of delivery and postnatal outcomes in pregnancies with absent or reversed end-diastolic (ARED) flow in the umbilical arteries. Study design: Postnatal outcomes of 103 newborns of pregnancies with a diagnosis of ARED flow on Doppler velocimetry of the umbilical arteries were analyzed retrospectively between January 1997 and December 2004. Single pregnancies and fetuses without malformations were included. The cases were divided into two groups according to the flow during atrial contraction (a-wave) in the ductus venosus on the day of delivery: group A, 20 cases with absent or reversed flow in the ductus venosus and group B, 83 cases with positive flow. The results were analyzed statistically using the chi-square test, Fisher`s exact test and the Mann-Whitney U test with the level of significance set at 5%. Results: All newborns were delivered by cesarean section. Gestational age was similar in the two groups (group A: 30 weeks and group B: 30.9 weeks, P = 0.23). Absent or reversed ductus venosus flow was associated with the following adverse postnatal outcomes: lower birthweight (P < 0.001), lower Apgar scores in the first (P = 0.001) and fifth minute (P = 0.001), a higher frequency of orotracheal intubation (P = 0.001) and pH at birth less than 7.20 (P < 0.001), pulmonary hemorrhage (P = 0.03), thrombocytopenia (P = 0.02), hypoglycemia (P = 0.01), intracranial hemorrhage (P = 0.02), and postnatal death (P = 0.007). Conclusion: The study of ductus venosus flow may provide additional information regarding the best time for interruption of pregnancies with ARED flow in the umbilical arteries characterized by extreme prematurity. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Effect of sildenafil on clitoral blood flow and sexual response in postmenopausal women with orgasmic dysfunction

Objective: To analyze the effects of sildenafil citrate on clitoral blood flow and sexual response in postmenopausal women with orgasmic dysfunction. Method: In this randomized, double-blind, placebo-controlled trial 22 women received a 50-mg dose of sildenafil (n=11) or placebo (n=11) daily for 15 days. The Golombok Rust Inventory of Sexual Satisfaction (GRISS) was used for subjective evaluation of the sexual-response cycle. Clitoral blood flow was measured by color and pulse Doppler at baseline, after 1 hour of taking the first dose, and after 15 days of treatment. Results: Blood flow was significantly more improved in the sildenafit than in the placebo group (P<0.05), and a positive correlation between Doppler values and GRISS scores was noted in the sildenafil group after only 15 days of treatment. Conclusion: Sildenafil may improve clitoral blood flow and increase the GRISS scores in postmenopausal women with orgasmic dysfunction. (C) 2008 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

Effects of estradiol and norethisterone on lipids, insulin resistance and carotid flow

Objectives: To evaluate the lipid profile, insulin resistance and vasomotricity, and the interaction between these factors, in postmenopausal women receiving hormone therapy. Methods: A prospective, randomized, double-blind study was carried out in which 77 postmenopausal women received one of the three treatment regimens: (A) 2 mg oral micronized estradiol (E(2)) (n = 25); (B) 2 mg oral E(2) + 1 mg oral norethisterone acetate (NETA) (n = 28); or Q placebo (n = 24), daily for 6 months. Evaluations were carried out at baseline and at the end of treatment on lipid and lipoprotein profiles, homeostasis model assessment of insulin resistance (HOMA-IR) and pulsatility index (PI) of the internal carotid artery by Doppler ultrasonography. Results: Mean increases of 15.6% and 2.4% and a reduction of 6.4% in high-density lipoprotein (HDL) levels were found for the E(2), E(2) + NETA and placebo groups, respectively. Reductions of 9.5% and 3.7% and an increase of 12.1% in low-density lipoprotein (LDL), and reductions of 20.0% and 3.8% and an increase of 28.8% in the LDL:HDL ratio were found for the E(2), E(2) + NETA and placebo groups, respectively (p < 0.001 in all cases). Insulin levels and HOMA-IR decreased 12.8% and 12.3% in the E2 group and increased 12.9% and 16.0% in the E(2) + NETA group (p < 0.05), respectively. Carotid PI following treatment was 1.18 +/- 0.23, 1.38 +/- 0.20 and 1.41 +/- 0.21 for the E(2), E(2) + NETA and placebo groups, respectively (p = 0.0006). Conclusions: Oral estrogen therapy led to an improvement in lipid profile, insulin resistance and carotid blood flow, which was cancelled when NETA was associated. (c) 2008 Elsevier Ireland Ltd. All rights reserved.

Pulmonary morphofunctional effects of mechanical ventilation with high inspiratory air flow

Objective: Uncertainties about the numerous degrees of freedom in ventilator settings leave many unanswered questions about the biophysical determinants of lung injury. We investigated whether mechanical ventilation with high air flow could yield lung mechanical stress even in normal animals. Design. Prospective, randomized, controlled experimental study. Setting: University research laboratory. Subjects. Thirty normal male Wistar rats (180-230 g). Interventions: Rats were ventilated for 2 hrs with tidal volume of 10 mL/kg and either with normal inspiratory air flow (V`) of 10 mL/s (F10) or high V` of 30 mL/s (F30). In the control group, animals did not undergo mechanical ventilation. Because high flow led to elevated respiratory rate (200 breaths/min) and airway peak inspiratory pressure (PIP,aw = 17 cm H2O), two additional groups were established to rule out the potential contribution of these variables: a) normal respiratory rate = 100 breaths/min and V` = 30 mL/sec; and b) PIP,aw = 17 cm H2O and V` 10 mL/sec. Measurements and Main Results: Lung mechanics and histology (light and electron microscopy), arterial blood gas analysis, and type III procollagen messenger RNA expression in lung tissue were analyzed. Ultrastructural microscopy was similar in control and F10 groups. High air flow led to increased lung plateau and peak pressures, hypoxemia, alveolar hyperinflation and collapse, pulmonary neutrophilic infiltration, and augmented type III procollagen messenger RNA expression compared with control rats. The reduction of respiratory rate did not modify the morphofunctional behavior observed in the presence of increased air flow. Even though the increase in peak pressure yielded mechanical and histologic changes, type III procollagen messenger RNA expression remained unaltered. Conclusions: Ventilation with high inspiratory air flow may lead to high tensile and shear stresses resulting in lung functional and morphologic compromise and elevation of type III procollagen messenger RNA expression.

Flow-through peritoneal dialysis in neonatal enema-induced hyperphosphatemia

Fleet enemas are hypertonic solutions with an osmotic action and a high concentration of phosphate. When retained in the human body they have a great toxic potential, causing severe hydro-electrolyte disorders in children, especially in newborns. We report the case of a previously healthy 8-day-old newborn who needed neonatal intensive care treatment after the inadvertent administration of an osmotically active hypertonic phosphate enema. Taking into account that phosphate removal by peritoneal dialysis (PD) strongly depends on total dialysate turnover, we chose continuous flow PD (CFPD) as the treatment option, with a successful outcome. Clinical experience with this dialytic modality is limited to a few case reports in pediatric and adult patients. To the best of our knowledge, we report here the first description of CFPD in the setting of acute phosphate nephropathy in the neonatal period. The modality of PD described here has potential as an alternative management option as it is a highly efficient, methodologically simple, and low-cost method without any need for sophisticated equipment. Physicians and parents should be aware of the adverse effects of a hypertonic phosphate enema and should never use these medications in infants and newborns.

Introduction to Discounted Cash Flow Analysis and Financial Functions in Excel

The financial and economic analysis of investment projects is typically carried out using the technique of discounted cash flow (DCF) analysis. This module introduces concepts of discounting and DCF analysis for the derivation of project performance criteria such as net present value (NPV), internal rate of return (IRR) and benefit to cost (B/C) ratios. These concepts and criteria are introduced with respect to a simple example, for which calculations using MicroSoft Excel are demonstrated.

Iliac-hepatic arterial bypass for compromised collateral flow during modified Appleby operation for advanced pancreatic cancer

Involvement of the celiac trunk and common hepatic artery are two of the most common forms of vascular invasion by tumours of the distal pancreas, and until recently this finding was considered a contra-indication to resection. We described a modified Appleby operation for locally advanced distal pancreatic cancer with compromised hepatic collateral flow that needed hepatic arterial revascularization, successfully accomplished by left external iliac-hepatic arterial bypass with Dacron prosthesis. Patient recovery was uneventful and he was discharged on the 10th postoperative day. Postoperative angio-CT disclosed a patent arterial bypass. Patient is well and asymptomatic 13 months after operation. At the time of this writing, postoperative CT scan showed no evidence of disease and CA 19-9 level is normal. There is a well established rationale to perform extended resection of pancreatic carcinomas that compromise vascular structures. Modified Appleby procedure can safely be performed, has oncological advantages to palliative procedures and provides relief of pain but is reserved for selected patients. Preservation of hepatic arterial flow has utmost importance to avoid hepatobiliary complications as liver necrosis, liver abscess, gallbladder necrosis or cholecystitis. In this case, hepatic revascularization was particularly challenging, but was successfully accomplished by left external iliac-hepatic arterial bypass. To our knowledge this type of arterial bypass has never been described so far in the English literature and its description may be important for surgeons dealing with advanced pancreatic cancer. (C) 2009 Elsevier Ltd. All rights reserved.

Comparative Study of the Standard Fluorescent Antibody to Membrane Antigen (FAMA) Assay and a Flow Cytometry-Adapted FAMA Assay To Assess Immunity to Varicella-Zoster Virus

A flow cytometry-adapted fluorescent antibody to membrane antigen (FAMA) assay to detect IgG antibodies against varicella-zoster virus (VZV) was developed and tested in 62 serum samples, showing 90.32% accuracy obtained from a receiver operating characteristic (ROC) curve with a 0.9125 (95% confidence interval [CI], 0.829 to 1.00) area below the curve compared to the result with standard FAMA.

Fetal hemodynamic changes following maternal betamethasone administration in pregnancies with fetal growth restriction and absent end-diastolic flow in the umbilical artery

Objectives. To examine the effects of betamethasone administration on umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) Doppler flow. Design. Longitudinal prospective study. Setting: Fetal Surveillance Unit, Department of Obstetrics and Gynecology, University of Sao Paulo, Sao Paulo, Brazil. Population. Thirty-two singleton pregnancies complicated by fetal growth restriction with absent end-diastolic flow in the UA. Methods. Pulsatility index (PI) of the UA, MCA and DV was measured from 26 to 34 weeks prior to and within 24 or 48 hours after starting betamethasone treatment course. Analysis of variance for repeated measures was used to determine the changes in the fetal hemodynamic Doppler flow following maternal corticosteroid administration. Main outcome measures. Improvement of UA-PI within 24 hours and DV-PIV (venous pulsatility) within 48 hours from the first betamethasone dose. Results. Mean gestational age at delivery was 29.3 (1.8) weeks and birthweight was 806.6 (228.2) g. A reduction in the UA-PI was observed in 29 (90.6%) cases, with return of end-diastolic flow in 22 (68.7%). The mean UA-PI were 2.84 (0.52) before corticosteroid administration, 2.07 (0.56) within 24 hours and 2.42 (0.75) after 48 hours, with a significant difference along the evaluations (p0.001). No significant changes in the MCA Doppler were observed. DV-PIV decreased from 1.06 (0.23) prior corticosteroids administration to 0.73 (0.16) within 24 hours and 0.70 (0.19) after 48 hours (p0.001). Conclusions. There was reduction in the umbilical artery and in the DV pulsatility indices within 24 hours from betamethasone administration that was maintained up to 48 hours.

Initial hepatosplanchnic blood flow distribution and oxygen metabolism in experimental model of hypotensive brain death

Background: Organs from the so-called marginal donors have been used with a significant higher risk of primary non function than organs retrieved from the optimal donors. We investigated the early metabolic changes and blood flow redistribution in splanchnic territory in an experimental model that mimics marginal brain-dead (BD) donor. Material/Methods: Ten dogs (21.3 +/- 0.9 kg), were subjected to a brain death protocol induced by subdural balloon inflation and observed for 30 min thereafter without ally additional interventions. Mean arterial and intracranial pressures, heart rate, cardiac output (CO), portal vein and hepatic artery blood flows (PVBF and HABF, ultrasonic flowprobe), and O(2)-derived variables were evaluated. Results: An increase in arterial pressure, CO, PVBF and HABF was observed after BD induction. At the end, an intense hypotension with normalization in CO (3.0 +/- 0.2 VS. 2.8 +/- 2.8 L/min) and PVBF (687 +/- 114 vs. 623 +/- 130 ml/min) was observed, whereas HABF (277 33 vs. 134 28 ml/min, p<0.005) remained lower than baseline values. Conclusions: Despite severe hypotension induced by sudden increase of intracranial pressure, the systemic and splanchnic blood flows were partially preserved without signs of severe hypoperfusion (i.e. hyperlactatemia). Additionally, the HABF was mostly negatively affected in this model of marginal BD donor. Our data suggest that not only the cardiac output, but the intrinsic hepatic microcirculatory mechanism plays a role in the hepatic blood flow control after BD.

Change in blood flow velocity demonstrated by Doppler ultrasound in upper limb after axillary dissection surgery for the treatment of breast cancer

The aim of this study was to evaluate the arterial and venous blood flow in women who underwent upper limb axillary dissection surgery for the treatment of breast cancer. Sixty women were divided into two groups: group 1 (G1)-30 women who underwent breast surgery with axillary dissection level II or III (55.6 +/- A 8.6 years); group 2 (G2)-control, 30 women with no breast cancer (57.4 +/- A 7.0 years). Blood flow profile was evaluated by a continuous wave ultrasound Doppler device (Nicolet Vascular Versalab SE(A (R))) with an 8 MHz probe. Axillary, brachial arteries and veins, arm circumference, volumes, and the ankle-brachial index (ABI) were examined. Wilcoxon test and Mann-Whitney tests were applied to analyze blood flow velocity intra-group and between G1 and G2, respectively. The G1 results showed no lymphedema and no peripheral arterial disease (ABI > 0.9). Moreover, the mean blood flow velocity of the vessels ipsilateral to the surgery was significantly higher than the contralateral ones for all vessels examined (P < 0.05). The mean velocity of blood flow of the vessels contralateral to surgery was significantly higher than the axillary artery in G2 (P < 0.05). It can be concluded that women who underwent axillary dissection due to breast cancer showed probable stenosis in the arterial and venous axillary and brachial vessels of the upper limb ipsilateral to the surgery, confirmed by the increase of blood flow velocity, and such obstruction might affect the limb contralateral to the operation site.