Plasma Neutrophil Gelatinase-associated Lipoprotein in Living Kidney Donors.

BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker for acute kidney injury. This study was conducted to determine the clinical implications of perioperative plasma NGAL levels for renal function after living donor nephrectomy. METHODS: Between July 2013 and May 2014, 112 donors underwent live donor nephrectomy at our institution. Donor plasma NGAL levels were measured perioperatively for 6 months. The relationship between perioperative plasma NGAL and recovery of renal function was analyzed. Renal function was estimated with the Modification of Diet in Renal Disease formula. RESULTS: Mean preoperative NGAL was 62.1 ± 29.5 ng/mL. Plasma NGAL was most elevated 1 week postoperatively (218 ± 95.5 ng/mL), and stabilized after 1 month (122.9 ± 45.3 ng/mL). Preoperative plasma NGAL was not correlated with donor age or preoperative estimated glomerular filtration rates (eGFR), but was negatively correlated with 6-month eGFR (r = -0.458, P < .001). During the observation period, plasma NGAL at 1 week was most correlated with 6-month eGFR (r = -0.554, P < .001). An ROC curve analysis showed that age, preoperative eGFR, and 1-week postoperative plasma NGAL were highly predictive of developing of chronic kidney disease (CKD), defined as eGFR <60 mL/min/1.73 m(2), 6 months postoperatively (AUC = 0.91, P < .001). One-week postoperative plasma NGAL was also independently associated with CKD risk at 6 months (odds ratio: 1.13 for each 10 ng/mL increase, P = .013). CONCLUSION: Plasma NGAL becomes elevated after kidney donation and can provide information about acute kidney injury during the compensatory hyperfiltration period. Donors with increased perioperative plasma NGAL require close observation because their possibility of developing CKD after donation may be greater.

Stretched arc discharge in produced water.

The objective of the present study was to investigate the feasibility of stretching an arc discharge in produced water to increase the volume of produced water treated by plasma. Produced water is the wastewater generated by hydraulic fracturing of shale during the production phase in shale-oil or shale-gas exploration. The electric conductivity of produced water is in the range of 50-200 mS/cm, which provides both a challenge and opportunity for the application of plasmas. Stretching of an arc discharge in produced water was accomplished using a ground electrode and two high-voltage electrodes: one positioned close to the ground electrode and the other positioned farther away from the ground. The benefit of stretching the arc is that the contact between the arc and water is significantly increased, resulting in more efficient plasma treatment in both performance and energy cost.

Cardiovascular benefits of phlebotomy: relationship to changes in hemorheological variables.

Renewed interest in the age-old concept of "bloodletting", a therapeutic approach practiced until as recently as the 19th century, has been stimulated by the knowledge that blood loss, such as following regular donation, is associated with significant reductions in key hemorheological variables, including whole blood viscosity (WBV), plasma viscosity, hematocrit and fibrinogen. An elevated WBV appears to be both a strong predictor of cardiovascular disease and an important factor in the development of atherosclerosis. Elevated WBV through wall shear stress is the most direct physiological parameter that influences the rupture and erosion of vulnerable plaques. In addition to WBV reduction, phlebotomy may reduce an individual's cardiovascular risk through reductions in excessive iron, oxidative stress and inflammation. Reflecting these findings, blood donation in males has shown significant drops in the incidence of cardiovascular events, as well as in procedures such as percutaneous transluminal coronary angioplasty and coronary artery bypass grafting. Collectively, the available data on the benefits of therapeutic phlebotomy point to the importance of monitoring WBV as part of a cardiovascular risk factor, along with other risk-modifying measures, whenever an increased cardiovascular risk is detected. The development of a scanning capillary tube viscometer allows the measurement of WBV in a clinical setting, which can prove to be valuable in providing an early warning sign of an increased risk of cardiovascular disease.

Note: an underwater multi-channel plasma array for water sterilization.

A simple yet effective method to generate multi-channel plasma array in water is presented in this paper. Thin circular metal disks sandwiched between dielectric layers were used, allowing the production of large-volume underwater plasma array with higher stability. The system can be further scaled up by stacking multiple metal disks, making it suitable for large-scale industrial water treatment. Generation of UV and reactive species was identified by optical emission spectroscopy. Sterilization experiments were performed. Results show that the device was effective in deactivating E. coli in water over a wide range of initial concentrations ranging from 10(4) to 10(8) CFU/ml.

Effect of hemodialysis on whole blood viscosity.

PURPOSE: The purpose of the present study was to examine the effect of hemodialysis procedures on the hemoconcentration status of end-stage renal disease (ESRD) patients. METHODS: We measured whole blood viscosity (WBV) of 30 ESRD patients using a scanning-capillary-tube viscometer before and after hemodialysis. The blood sample size required for WBV measurements was approximately 3 mL. Pre-dialysis specimens for viscosity measurements were obtained via the fistula needle or Perma catheter prior to initiating hemodialysis, and post-dialysis specimens were drawn from the arterial sample port of the hemodialysis line 3.5 hours after initiation of dialysis treatment. RESULTS: Changes in WBV were measured at high and low shear rates: 80% of patients showed an increased high shear viscosity, whereas 73% of patients demonstrated an increased low shear viscosity. The actual percentage increase in WBV observed after hemodialysis at high and low shear rate ranges varied broadly in the 30 patients. CONCLUSIONS: The observed increase in the WBV of ESRD patients over hemodialysis procedures indicates that a segment of patients experience increased flow resistance, particularly at the microcirculatory level. In addition, for the segment of patients experiencing marked increases in WBV during hemodialysis, the vessel wall at the dialysis fistula is exposed to blood with a higher viscosity than at the beginning of the process. The higher blood viscosity at the dialysis fistula is directly related to increased kinetic force and shear stress on the vessel wall, which may be playing a role in increasing the risk of stenosis.

Monthly variations in self-reports of alcohol consumption.

OBJECTIVE: This study examines monthly variation in reports of recent alcohol consumption behavior. METHOD: Telephone survey data collected by the Behavioral Risk Factor Surveillance System were used to measure self-reports of drinking and heavy episodic drinking in the 30 days before the interview. The sample (N = 57,758) comprised cases collected in six states in 5 selected years. Monthly variability in self-reported alcohol consumption was evaluated by logistic regression analysis, using "deviation from means coding" for the month of interview, with background variables and year of interview controlled and state-level clustering adjusted. RESULTS: Adults were significantly more likely to report past 30-day alcohol consumption when interviewed during the month of January and less likely to report consumption when interviewed during March. Respondents were also more likely to report heavy episodic drinking during the month of July. Despite large differences in alcohol consumption between male and female participants, these seasonal patterns were essentially the same for both genders. CONCLUSIONS: The findings suggest that assessments of alcohol consumption that do not consider seasonal variation may be biased. In order to minimize this bias, it is recommended that researchers avoid collecting data only during these particular times of the year or extend the data collection interval and control for seasonal variability.

Maintenance of a smoking cessation program in public health clinics beyond the experimental evaluation period.

OBJECTIVES: As phase 3 of a study to evaluate a smoking cessation program in public health practice, the authors assess the maintenance and impact of the It's Time smoking cessation program in seven public maternal and child health clinics in Chicago. METHODS: The authors interviewed 404 clinic patients in the study's baseline phase (prior to introduction of the It's Time intervention program), and 610 in the program maintenance phase (in the year after experimental evaluation had ended) to assess exposure to smoking cessation interventions offered at the clinic, and smoking cessation outcomes (quit, actions toward quitting, scores on action, motivation, readiness, and confidence scales). The authors controlled for clustering of smokers within clinics, smokers' characteristics prior to clinic visit, and type of clinic service. They compared outcomes by study group (control or intervention) to which each clinic had been assigned in the earlier experimental phase. RESULTS: Compared to baseline, smokers in the maintenance phase had greater exposure to posters, provider advice and booklet, and better outcomes on seven of eight smoking cessation measures, including quitting. These improvements were larger for clinics with prior experience implementing It's Time. CONCLUSION: Participation in the experimental evaluation of the It's Time program prepared and possibly motivated the clinics to continue the program. Continuing the program resulted in greater delivery of interventions and improved smoking cessation outcomes for smokers in the clinics.

Physiological flow simulation in residual human stenoses after coronary angioplasty.

To evaluate the local hemodynamic implications of coronary artery balloon angioplasty, computational fluid dynamics (CFD) was applied in a group of patients previously reported by [Wilson et al. (1988), 77, pp. 873-885] with representative stenosis geometry post-angioplasty and with measured values of coronary flow reserve returning to a normal range (3.6 +/- 0.3). During undisturbed flow in the absence of diagnostic catheter sensors within the lesions, the computed mean pressure drop delta p was only about 1 mmHg at basal flow, and increased moderately to about 8 mmHg for hyperemic flow. Corresponding elevated levels of mean wall shear stress in the midthroat region of the residual stenoses, which are common after angioplasty procedures, increased from about 60 to 290 dynes/cm2 during hyperemia. The computations (Ree approximately equal to 100-400; alpha e = 2.25) indicated that the pulsatile flow field was principally quasi-steady during the cardiac cycle, but there was phase lag in the pressure drop-mean velocity (delta p - u) relation. Time-averaged pressure drop values, delta p, were about 20 percent higher than calculated pressure drop values, delta ps, for steady flow, similar to previous in vitro measurements by Cho et al. (1983). In the throat region, viscous effects were confined to the near-wall region, and entrance effects were evident during the cardiac cycle. Proximal to the lesion, velocity profiles deviated from parabolic shape at lower velocities during the cardiac cycle. The flow field was very complex in the oscillatory separated flow reattachment region in the distal vessel where pressure recovery occurred. These results may also serve as a useful reference against catheter-measured pressure drops and velocity ratios (hemodynamic endpoints) and arteriographic (anatomic) endpoints post-angioplasty. Some comparisons to previous studies of flow through stenoses models are also shown for perspective purposes.

Effective deacetylation of chitin under conditions of 15 psi/121 degrees C.

Deacetylation of chitin under autoclaving conditions (15 psi/121 degrees C) was evaluated for the preparation of chitosan under different NaOH concentrations and reaction times. Deacetylation was effectively achieved by treatment of chitin under elevated temperature and pressure with 45% NaOH for 30 min and a solids/solvent ratio of 1:15. Treated chitosan showed similar nitrogen content (7.42%), degree of deacetylation (90.4%), and molecular mass (1560 kDa) but significantly higher viscosity values (2025 cP) compared with those (7.40%, 87.6%, 1304 kDa, and 143 cP, respectively) of a commercial chitosan. Reduction of the solids/solvent ratio from 1:15 to 1:10 did not affect degree of deacetylation, viscosity, and molecular mass of chitosan.

The effect of a structured smoking cessation program, independent of exposure to existing interventions.

OBJECTIVES: This study assessed the effectiveness of a smoking cessation program for women in public health clinics, controlling for reported exposures to 4 common intervention components (provider advice, booklet, video segment, posters) among smokers in the control group. METHODS: After a baseline control period, 10 pair-matched clinics were randomly assigned to study groups. A total of 1042 smokers in the combined baseline and control groups and 454 smokers in the intervention group completed a preintervention questionnaire and a postintervention telephone interview 5 to 8 weeks later. Eight smoking outcomes, including quitting, were analyzed for the effect of reported exposure to intervention components, experimental program, and clinic service. RESULTS: Greater exposure to intervention components, being in the experimental program, and being seen in prenatal clinics independently improved smoking outcomes. CONCLUSIONS: The number of interventions reported by smokers in the control group ranged from none to 4 and varied across clinic services. The experimental program we tested produced better outcomes than the minimal smoking cessation interventions already existing in the control clinics, after we controlled for whether smokers were or were not exposed to these interventions.

Minimal smoking cessation interventions in prenatal, family planning, and well-child public health clinics.

OBJECTIVES: This study assessed the prevalence and effectiveness of smoking cessation interventions for women of childbearing age in public health clinics. METHODS: Smokers in prenatal, family planning, and well-child services in 10 public health clinics (n = 1021) were interviewed 5 to 8 weeks after a medical visit to assess their exposure to smoking cessation interventions and smoking cessation outcomes. RESULTS: Depending on clinic service and intervention component (poster, video segment, provider advice, booklet), 16% to 63% of women reported exposure to an intervention component during their visit. Women in prenatal services received more interventions and had better outcomes than those in the other services. CONCLUSIONS: Exposure to more interventions increased readiness and motivation to quit and the number of actions taken toward quitting.

Catheter obstruction effect on pulsatile flow rate--pressure drop during coronary angioplasty.

The coupling of computational hemodynamics to measured translesional mean pressure gradients with an angioplasty catheter in human coronary stenoses was evaluated. A narrowed flow cross section with the catheter present effectively introduced a tighter stenosis than the enlarged residual stenoses after balloon angioplasty; thus elevating the pressure gradient and reducing blood flow during the measurements. For resting conditions with the catheter present, flow was believed to be about 40 percent of normal basal flow in the absence of the catheter, and for hyperemia, about 20 percent of elevated flow in the patient group. The computations indicated that the velocity field was viscous dominated and quasi-steady with negligible phase lag in the delta p(t)-u(t) relation during the cardiac cycle at the lower hydraulic Reynolds numbers and frequency parameter. Hemodynamic interactions with smaller catheter-based pressure sensors evolving in clinical use require subsequent study since artifactually elevated translesional pressure gradients can occur during measurements with current angioplasty catheters.

Evaluation of a motivational smoking cessation intervention for women in public health clinics.

BACKGROUND: A multicomponent motivational smoking cessation intervention was evaluated in 33 prenatal, family planning, and pediatric services in 12 public health clinics. Clinic-based intervention components were implemented by clinic personnel as part of routine medical visits. METHODS: The evaluation design included pre- and postintervention measurements of multiple study outcomes in a baseline (all clinics prior to the start of the intervention) and an experimental period (matchedpair random assignment of clinics to intervention or control conditions). Subjects were 683 (baseline) and 1,064 (experimental) smokers with measurements of smoking outcomes at both times. Mixed-effects regressions analyzed individual outcomes clustered within clinics and services. RESULTS: Control and intervention clinics had similar outcomes in the baseline period. In the experiment, outcomes improved in the intervention but not in the control clinics. Compared to controls, smokers exposed to the intervention were more likely to have quit (14.5 versus 7.7%) or take actions toward quitting and had higher mean action, stage of readiness, and motivation to quit scores. These positive effects persisted when clustering within clinics and services was controlled. CONCLUSIONS: This intervention, implemented by clinic personnel as part of routine medical visits, was effective under these natural conditions across different types of clinic service.

Measuring readiness and motivation to quit smoking among women in public health clinics: predictive validity.

We conducted an independent pilot test of the internal consistency, stability, and predictive validity of the instrument presented by Crittenden, Manfredi, Lacey, Warnecke, and Parsons (1994) using a two-wave panel of female smokers in 12 public health clinics. This instrument subdivides the precontemplation stage proposed by Prochaska and DiClemente into three more distinct stages: not contemplating quitting or cutting down, not contemplating quitting, and not contemplating quitting within 6 months. Findings confirm that the instrument is useful for evaluating movement toward quitting for populations that are largely concentrated in the precontemplative stage. The concurrent and predictive validity of the elaborated stages and the reliability and stability of smoking motivation and confidence indicate that the instrument is sensitive enough to track changes in readiness and motivation across the full readiness continuum.

Hemodynamic changes in recurrent intracranial terminal aneurysm after endovascular treatment.

RATIONALE AND OBJECTIVES: Multiple cases of recurrence of aneurysms after endovascular treatment have been reported. The purpose of the current hemodynamic study was to identify changes in shear stress and pressure associated with the recurrence of terminal intracranial aneurysms after endovascular occlusion. METHODS: Using a finite element method, a pulsed flow with a non-Newtonian viscosity of blood was simulated within the aneurysm cavity. A recurrent terminal intracranial aneurysm of a patient originally treated with balloon occlusion was then studied. This was based on a physiologic pulsatile flow, which was observed in the middle cerebral artery. Before and after the balloon occlusion, local maximum wall shear stress and pressure drop at the neck of the aneurysm were calculated and compared with the normal shear stress. RESULTS: Although the maximum shear stress at the right neck of the aneurysm was significantly reduced after balloon insertion, it was still 2.5 times greater than the normal maximum shear stress. This was attributable to the presence of a portion of the aneurysmal neck (residual neck), which was not obliterated by the balloon. The balloon also helped to reduce the maximum pressure inside the aneurysm by approximately 15%. Hemodynamic changes in the residual aneurysm neck, where the shear stress and the pressure are high, and other factors may be responsible for the recurrence of aneurysms after balloon or coil occlusion. CONCLUSION: Residual necks after balloon occlusion, coil occlusion, or both are attributable to the geometric orientation of the aneurysm with respect to parent and daughter vessels and the variety of configurations of the balloon and coils used to occlude the aneurysms. Inadequate reduction in local shear stress found in these residual necks is an important factor in the recurrence and rupture of the aneurysm after endovascular occlusion.

Flow-pressure drop measurement and calculation in a tapered femoral artery of a dog.

This study describes the in vivo measurement of pressure drop and flow during the cardiac cycle in the femoral artery of a dog, and the computer simulation of the experiment based on the use of the measured flow, vessel dimensions and blood viscosity. In view of the experimental uncertainty in obtaining the accurate velocity profile at the wall region, the velocity pulse at the center was measured and numerical calculations were performed for the center line instantaneous velocity and within the two limits of spatial distribution of inlet flow conditions: uniform and parabolic. Temporal and spatial variations of flow parameters, i.e., velocity profile, shear rate, non-Newtonian viscosity, wall shear stress, and pressure drop were calculated. There existed both positive and negative shear rates during a pulse cycle, i.e., the arterial wall experiences zero shear three times during a cardiac cycle. For the parabolic inlet condition, the taper of the artery not only increased the magnitude of the positive and negative shear rates, but caused a steep gradient in shear rate, a phenomenon which in turn affects wall shear stress and pressure. In contrast, for the uniform inlet condition, the flow through the tapered artery was predominantly the developing type, which resulted in reduction in magnitude of wall shear rate along the axial direction.

Numerical studies of three-dimensional arterial flows in reverse curvature geometry: Part I--Peak flow.

A three-dimensional flow simulation at Repeak = 192 and 580 was made in a smooth reverse curvature model that conformed to the gentle "S" shape from a human left femoral artery angiogram. The objective of this numerical investigation was to find the changes in pressure, shear stress, velocity profile, and particle path occurring in the double-curved arterial vessel. Due to the impingement of blood at the outer wall in the first bend region, the wall shear stress approached 40 dyne/cm2--a value over twice as large as in the straight upstream segment. Conversely, at the inner wall in the first bend, a low shear stress region was found where the value of the shear stress was consistently smaller than that in the straight section. The initiation of centrifugal effects caused by the first bend could clearly be seen at Repeak = 580, but due to the close proximity of the reverse curvature segment, the momentum effect due to the second bend overshadowed the centrifugal effect. Hence, only near the end of the second bend did the centrifugal effect due to the second bend result in a double-spiral-secondary motion. In addition, the numerically calculated pressure drop data were in agreement with prior experimental values.

Two-dimensional pulsatile hemodynamic analysis in the magnetic resonance angiography interpretation of a stenosed carotid arterial bifurcation.

A two-dimensional pulsatile hemodynamic analysis based on the finite-element technique was performed on a minimally stenosed carotid artery to identify the possible explanation for the differences in the x-ray and magnetic resonance carotid angiograms of a patient. The magnetic resonance angiogram was obtained by applying the maximum intensity projection algorithm to axial slices, acquired using the time-of-flight principle. The differences in the x-ray and magnetic resonance depictions were interpreted based on velocity profile, wall shear stress, and streamline data provided by the hemodynamic analysis. The specific contribution of the stenosis was further isolated from that of the bifurcation by comparing the flow patterns within the stenotic artery with those of its normal counterpart. The Doppler spectral velocity wave form of the patient constituted the basis for the pulsatile flow velocity specification. The analysis took into consideration the non-Newtonian viscosity of blood. The numerical procedure was validated through different convergence criteria and through shear stress comparisons. The importance of hemodynamic analyses in relation to magnetic resonance angiography was further discussed along with possible shortcomings of the technique.

Conceptions of alcoholism among Koreans and Americans.

Ethnographic research has occasionally reported the presence (or absence) of the disease concept of alcoholism in non-Western cultures. But the problem of differences in the nature of the concept of alcoholism between cultures in which it exists has not been seriously investigated. This study contrasts beliefs about alcoholism among samples of Koreans and Americans at a university in the United States. The findings suggest that the concept of alcoholism is present in both cultures, but Koreans tend to restrict their disease to the physiological consequences of long-term alcohol use, while Americans accept a definition which is couched largely in social and behavioral terms. It thus appears that, in contrast to America, alcohol consumption in Korea is relatively high, but alcoholism is rare. The implications of these findings for drinking behaviors, and the diagnosis and treatment of alcoholism, are discussed.

Intracranial aneurysms: flow analysis of their origin and progression.

PURPOSE: To explain the origin and growth of intracranial aneurysms using the hemodynamic data obtained from a computer simulation. MATERIALS AND METHODS: Pulsatile flow in an intracranial aneurysm cavity was numerically simulated based on physiologic pulsatile flow observed in the aorta. A finite element method was applied to solve the equations of motion and the non-Newtonian viscosity of blood was taken into account in the analysis. An angiogram of a middle cerebral artery segment with aneurysm was used for the computer modeling of blood flow within the aneurysm cavity. Local shear stress and pressure on the wall at the neck of the aneurysm as well as blood flow motions inside the cavity were calculated as a function of time for various stages in the development of the aneurysm. FINDINGS: Blood moves into the aneurysm cavity along the proximal wall of the cavity and emerges along the distal wall during the acceleration period of systole; however, during the deceleration period of systole and diastole, blood changes its flow direction, entering along the distal wall of the cavity and leaving along the proximal cavity wall. Rapid changes of blood flow direction result in rapid changes in wall shear stress and pressure at the proximal and distal walls of the cavity, rendering continuous damage to the intima at the cavity neck. These hemodynamic stresses relate to the anatomy of a particular vessel may be responsible for the initiation of aneurysm formation and subsequent progression, thrombosis and/or rupture. CONCLUSION: Computer modeling can further our understanding of factors that determine the origin and progression of intracranial aneurysms.