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PubMedDate not supplied

The relationship between urine volume and drain volume as determinants of fractional urea clearance in continuous peritoneal dialysis.

A logistic regression model developed and validated in Albuquerque identified 24 hr urine volume (UV) and 24 hr drain volume/(body water) (DV/V) as predictors of fractional urea clearance (KT/V) in continuous peritoneal dialysis (CPD). Solution of this model provided DV/V values consistent with KT/V at least equal to a target KT/V for a given UV. The predictive accuracy of these unique DV/V values was tested in urea kinetic studies performed in 108 CPD patients in Thessaloniki and Athens with UV varying between 0 and 2 L/24 h. Two target weekly KT/V values, 1.70 and 1.90, were investigated. The equation DV/V = (5.2811-3.6996 UV)/ 17.554, derived by solving the logistic regression model, detected weekly KT/V > 1.70 (69/108, or 63.9% of the studies) with a sensitivity of 87.3% and a specificity of 60.4%. According to the same equation, the maximal UV consistent with weekly KT/V < or = 1.70 is 1.427 L/24 hr. The equation DV/V = (5.4994-2.6007 UV)/17.007 detected weekly KT/V > 1.90 (44/108, or 40.7% of the studies) with a sensitivity of 90.3% and a specificity of 79.2%. According to this equation, the maximal UV consistent with weekly KT/V < or = 1.90 is 2.115 L/24 hr. Determination of the lowest daily DV consistent with a target KT/V at any daily UV (within a wide range) is feasible in CPD.

Feasibility Studies↗
PubMedDate not supplied

Oxygen availability during hypothermic cardiopulmonary bypass.

Oxygen availability during cardiopulmonary bypass was assessed in 22 patients under hypothermic and relatively normothermic conditions. The patients were divided into two groups, 17 of whom received ACD blood and 5, CPD blood. The mean P50 for all patients fell from a preoperative value of 25.9 +/- 2.4 (SD) to 15.6 +/- 2.1 during hypothermia confirming a leftward shift of the oxyhemoglobin dissociation curve. Oxygen uptake, calculated from a-v oxygen content differences (avDO2) and flow, was significantly lower during hypothermic bypass (65 +/- 27 ml/min) than during rewarming (121 +/- 41 ml/min). The increase in oxygen affinity during hypothermia was influenced also by changes in acid base and 2,3-DPG concentrations, the changes being similar in both the ACD and CPD groups of patients. During rewarming, however, oxygen availability was increased in the CPD group presumably from significantly increased 2,3-DPG concentrations. A "functional" value of hemoglobin, based upon the effects of the shift of the oxyhemoglobin dissociation curve and, therefore, reflecting the true capacity of hemoglobin to unload oxygen at the tissue level, was calculated. During the hypothermic phase of bypass, this functional hemoglobin was only 4.2 g/100 ml blood, suggesting that, in spite of reduced metabolic demands, oxygenation reserves are minimal.

Adult↗
PubMed2002

Continuous potential display of ictal electrocorticography.

The objective of this study was to determine whether the animation of electrical activity recorded on ictal electrocorticograms (ECoGs) can demonstrate the propagation of seizure discharges from the epileptogenic zone (EZ) to the surrounding cortical area. A computer program, continuous potential display (CPD), was designed to animate the color-coded potential changes in 5-msec intervals at each recorded site. This program was used to analyze 35 ictal ECoGs recorded by subdural grid electrodes from 11 subjects who underwent epilepsy surgery for intractable partial seizures. Continuous potential display demonstrated recurrent cycles of seizure propagation from the EZ to the surrounding cortical area even when seizure discharges appeared widespread on ECoG. Hence, the EZ could be mapped at any time during the seizure course. The EZ mapped by analyzing a small fraction of ECoG during widespread seizure discharges using CPD only overlapped 69 +/- 24% (mean +/- standard deviation) of the surgical area. The EZ mapped by CPD had 34 +/- 22% false positives and 35 +/- 27% false negatives. Animation of potential changes recorded by ictal ECoG can assist in studying the temporal and spatial patterns of seizure propagation and in mapping the EZ for surgical resection.

Action Potentials↗
PubMed1991

Contrast-sensitivity loss in a group of former microelectronics workers with normal visual acuity.

The measurement of contrast sensitivity at varying grating frequencies is used increasingly to study visual and neural disorders. It provides more information than conventional acuity measures. Refractive errors initially affect high spatial frequencies, whereas lower spatial frequencies are affected only when these errors are pronounced. Neurophysiological alterations are reflected by depressed sensitivity to coarse gratings. Visual dysfunction has been associated with workplace exposures to a wide range of organic solvents. In microelectronics assembly where large quantities of organic solvents are used in many aspects of the work processes, visual deficits have been observed. The objective of the present study was to compare contrast sensitivity among former microelectronics assembly workers, with normal far and near visual acuity, and a reference group from the same region, with similar acuity. No significant differences were observed between scores at the two ends of the contrast sensitivity curves; however, at the intermediate spatial frequencies, the former microelectronics workers' scores were significantly lower (Student's t-test; p less than 0.05). For the microelectronics workers, no relation was observed between age and contrast sensitivity at any spatial frequency, whereas for the reference group, contrast sensitivity scores were progressively lower with age at spatial frequencies greater than or equal to 6.0 cpd (r2 = 0.15 at 6 cpd to r2 = 0.45 at 18.0 cpd), suggesting that for the former there is some form of interference with the expected contrast sensitivity loss with age. Lower contrast sensitivity scores in intermediate spatial frequencies, observed among the former microelectronics workers, possibly reflect neural alterations, which may have resulted from exposure to neurotoxic substances. These findings suggest the need for further studies on visual functions in microelectronics workers.

Adult↗
PubMed2002

Contact lens drying and visual performance: the vision cycle with contact lenses.

BACKGROUND AND PURPOSE: The purpose of this study was to measure the effect of precontact lens tear film break-up on visual performance. METHODS: Four asymptomatic soft contact lens wearers had contrast sensitivity measured by a temporal, two-alternative, force choice paradigm combined with a self-paced methods of limits. Stimuli were vertically orientated sine wave gratings (0.5 to 14 cycles per degree [cpd] presented for 16.67 ms. Contrast sensitivity was measured before precontact lens tear break-up by a stimuli presented 2 s after the blink. A post-tear layer break-up measurement taken with the stimuli presented after break-up had been observed by the use of a video camera attached to a Tearscope. RESULTS: Contrast sensitivity was found to be reduced following precontact lens tear film break-up for stimuli of 4, 6, and 10 cpd; the data approached significance at 14 cpd. Further reductions in contrast sensitivity were observed for one subject when measurements were continued for 4 s following break-up. CONCLUSIONS: Contrast sensitivity is significantly reduced for middle to high spatial frequencies when the precontact lens tear film dries and breaks up. The combination of observations of visual performance immediately following the blink (from earlier experiments) and measurements following tear film break-up in this experiment allows description of a "vision cycle" for contact lens wearers in the interval between blinks. It is suggested that break-up of the precontact lens tear film could account for the complaints of intermittent blurred vision in some contact lens wearers and may provide a stimulus to blinking in these individuals.

Blinking↗
PubMed1995

Contrast sensitivity in organic-solvent-induced chronic toxic encephalopathy.

This is a study of visual contrast sensitivity in a series of subjects with previously diagnosed occupational organic-solvent-induced chronic toxic encephalopathy. Contrast sensitivity was measured for 16 subjects using the Vistech VCTS 6500 chart. The results were compared with age-stratified normal data. Six of the 16 subjects (37.5%) recorded abnormal contrast sensitivity results. Monocular abnormalities were found for two (33%) of these subjects. Statistically significant abnormalities in contrast sensitivity were observed at the intermediate spatial frequencies of three cycles per degree (cpd; P < .0005), 6 cpd (P < .025), and 12 cpd (P < .01). We conclude that contrast sensitivity is abnormal in some cases of occupational organic-solvent-induced chronic toxic encephalopathy. Intermediate spatial frequency channel neurones in the visual system may be more vulnerable to solvent toxicity than those of low or high spatial frequency. Contrast sensitivity testing may be a useful adjunct in the diagnostic process for this disease. Further research involving larger numbers of subjects is recommended.

Adult↗
PubMed2004

Effects of dominant and nondominant eyes in binocular rivalry.

PURPOSE: To investigate the relation between sighting and sensory eye dominance and attempt to quantitatively examine eye dominance using a balance technique based on binocular rivalry. METHODS: The durations of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 14 subjects. The dominant eye was determined by using the hole-in-card test (sighting dominance). In study 1, contrast of the target in one eye was fixed at 100% and contrast of the target in the other eye was varied from 100% to 80% to 60% to 40% to 20%, when using rectangular gratings of 1, 2, and 4 cycles per degree (cpd) at 2 degrees, 4 degrees , and 8 degrees in size. In study 2, contrast of the target in the nondominant eye was fixed at 100% and contrast of the target in the dominant eye was varied from 100% to 80% to 60% to 40% to 20%, when using a rectangular grating of 2 cpd at 4 degrees in size. RESULTS: In study 1, the total duration of exclusive visibilities of the dominant eye target; that is, the target seen by the eye that had sighting dominance was longer compared with that of the nondominant eye target. When using rectangular gratings of 4 cpd, mean total duration of exclusive visibility of the dominant eye target was statistically longer than that of the nondominant eye target (p < 0.05). In study 2, reversals (in which duration of exclusive visibility of the nondominant eye becomes longer than the dominant eye when the contrast of the dominant eye target is decreased) were observed for all contrasts except for 100%. CONCLUSIONS: The dominant sighting eye identified by the hole-in-card test coincided with the dominant eye as determined by binocular rivalry. The contrast at which reversal occurs indicates the balance point of dominance and seems to be a useful quantitative indicator of eye dominance to clinical applications.

Adult↗
PubMed2000

Is the practice of psychological therapists evidence-based?

An interview-based survey of evidence-based practice (EBP) and the research, continuing professional development (CPD) and audit activity that support it was conducted in the North East of England amongst a representative sample of NHS clinical psychologists and counsellors (n = 30). It profiled their participation in EBP activities over the past year and their intentions for the next year. The findings suggest that the sample had used guidelines and protocols on 56 per cent of occasions, had on average drawn on research, CPD and audit approximately half of the time, but had been only minimally influenced by research, CPD or audit. It is concluded that EBP has occurred in all defined areas and that the conditions for an increased degree of EBP are promising.

Adult↗
PubMedDate not supplied

Continuing professional development: does it make a difference?

Continuing professional development (CPD) is costly in terms of both organizational resources and personal time and effort. It forms an important part of the strategy for modernizing the health service and is an expectation of qualified nurses. There is little evidence to demonstrate the impact of CPD in terms of improved patient care and services. A small pilot study was undertaken. A group of intensive therapy unit (ITU) managers developed a goal attainment scale (GAS) to evaluate the impact of an ITU course. Results suggest that the ITU course did make a difference to the development of ITU nurses, but the nurses who did not take the course also developed. This has implications for service providers and educationalists in terms of expectations, timing and content of courses. The GAS was a useful tool as an approach to evaluating the impact of CPD but requires more rigorous testing before it can be described as reliable and valid.

Critical Care↗
PubMed1985

Prolonged ethanol replacement by CO2 increases splits on articular cartilage surface after critical point drying.

Ethanol replacement by CO2 of glutaraldehyde-fixed and ethanol-dehydrated rabbit articular cartilage specimens was monitored with both gas chromatograph and alcometer prior to critical point drying (CPD). The surface structure of the patellar specimens was also systematically registered with a semiquantitative scanning electron microscopic method. After a 2 h interval, when about 28 microliters of ethanol/15 min CO2 extract was removed, the articular surface was smooth, although small areas of striated surface and superficial splits were present. A long-term CO2 treatment (16 h) removed ethanol completely, but increased superficial splitting of the articular surface after CPD. Air-drying of the specimens gave rise to inferior preservation of the cartilage: large areas with pitted and leafy surface qualities, but no superficial splits, were present on the surface. It was evident that prolonged ethanol replacement by CO2, prior to CPD, degraded surface structure of the articular cartilage which should be taken into consideration in the planning and design of experiments. Ethanol removal by CO2 could conveniently be monitored by an alcometer.

Animals↗
PubMed1992

Immunomodulatory activity of different blood products on the mitogen-induced human lymphocyte transformation.

Blood transfusions have an immunosuppressive effect on the recipient and induce changes in several immunological parameters. We studied the effect of homologous and autologous fresh plasma (FP), fresh frozen plasma (FFP), heparinized plasma, as well as the influence of red blood cells (RBC), CPDA-1, CPD, heparin, PAGGS-mannitol, SAG-mannitol and ADSOL on mitogen-induced lymphocyte transformation. Both homologous and autologous FP and FFP decreased the PHA and ConA response of human lymphocytes (P < 0.05). The PWM response was reduced by FP (P < 0.05). The mean t1/2 of plasma-induced suppression was approximately 38 h. Dose-dependent suppression rates were observed with pure CPDA-1 and CPD solutions. In contrast, heparinized plasma showed an elevated PHA- and ConA-induced transformation rate (P < 0.025), whereas PWM induction was unaffected. In addition, washed RBC, pure PAGGS-M, SAG-M and ADSOL solutions revealed no effect on the PHA response. Freezing, heating or recalcification of plasma resulted in an increase in the PHA response. Adenine was not immunosuppressive in vitro. We conclude that, in addition to unspecific mechanisms by CPDA-1 or CPD, an unknown plasma factor, which is susceptible to changes in temperature or storage conditions, suppresses the PHA-, PWM- or ConA-induced T-cell immune response. Further clinical studies are needed to correlate these observations with clinical phenomena.

Adenine↗
PubMed1983

Preservation of red blood cells: studies of erythrocyte adenine nucleotides using luminescence analysis.

The levels of ATP and total adenine nucleotides (ATP + ADP + AMP) were determined by firefly luciferase assay in red blood cells during storage for 5 weeks at 4 degrees C. With few exceptions, no significant differences in nucleotide levels were found between whole blood stored in CPD-adenine and various preparations of red blood cells in CPD-adenine or CPD with saline-adenine-glucose (SAG) as additive. The levels of ATP and total adenine nucleotides during storage are discussed in relation to glucose levels, extracellular pH and shelf life of the red blood cells.

Adenine Nucleotides↗
PubMed1984

Activation of blood coagulation, fibrinolytic and kallikrein systems during storage of plasma.

This study deals with the question of how blood coagulation, kallikrein and fibrinolytic systems are affected by storage of plasma at +6 degrees C. Blood was collected into citrate phosphate dextrose adenine (CPD) or acid citrate dextrose (ACD) and the plasma samples were stored at +6 degrees C for 35 days. Samples were taken at weekly intervals for assays of various parameters of the different systems. No significant changes were observed in the levels of the main thrombin inhibitor, antithrombin III. At the end of the storage period, however, fibrinopeptide A levels increased markedly, particularly in the ACD plasma, indicating thrombin activation. There was no change in the plasminogen level, but a decrease in the levels of antiplasmin and urokinase inhibitors and an increase in the level of the fibrinogen degradation fragment B beta 15-42 were observed, indicating activation of the fibrinolytic system. The level of antikallikrein activity decreased sharply in ACD plasma; CPD plasma was less affected. This decrease was parallel to the increase in spontaneous proteolytic activity and correlated with the increase in fibrinopeptide A. Prolonged storage of plasma of +6 degrees C thus resulted in the activation of coagulation, fibrinolytic and kallikrein systems and decrease in inhibitors. The activation was much more pronounced in ACD than in CPD plasma.

Anticoagulants↗
PubMed1987

Platelet storage lesion in second-generation containers: correlation with platelet ATP levels.

The nature of platelet lesion occurring with storage of platelet concentrates (PC) in second-generation containers was investigated using various storage media and storage periods up to 14 days. In CPD-plasma (control medium), the changes which occurred progressively during storage were loss of discoid shape, microscopic platelet aggregate formation, fragmentation and the appearance of disintegrated, 'balloon' forms. By day 14 less than 10% of the platelets were discoid in shape, the platelet count had decreased by 23%, and there was a 5-fold increase in the amount of lactate dehydrogenase in plasma. Associated with this was a decrease in the platelet oxygen consumption rate, D(O2), loss of cellular ATP and extent of ADP-induced shape change, and a decrease in the hypotonic shock response. These parameters decreased at a similar rate, with a 50% decrease (t1/2) at days 7-9. They correlated highly with each other during storage and also with a fall in pH. At day 14 of storage, mean pH was 6.1 +/- 0.3. To evaluate the effect of pH stabilization during storage, 4 mEq sodium bicarbonate was added to PC in CPD-plasma. Although pH maintenance was much improved, 7.2-6.6 during 14 days of storage, the same in vitro lesions developed, although more slowly. The t1/2 of the same parameters was prolonged for approximately two days. When PC were stored in a plasma-free physiologic salt solution whose salt composition was similar to CPD-plasma, the t1/2 of the parameters increased to 11-15 days of storage, although the platelets eventually developed the same in vitro lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMedDate not supplied

Change of excitability in brainstem and cortical visual processing in migraine exhibiting allodynia.

BACKGROUND: Clinical and neurophysiological manifestations of information processing associated with central sensitization are little known. Allodynic migraine (AM) can be caused by the sensitization of trigeminal neuron, but no study has reported on AM between attacks using blink reflex (BR) and pattern-reversal visual evoked potentials (PVEPs). OBJECTIVE: We explored the characteristics of AM between attacks associated with central sensitization using BR and PVEP. METHODS: We recruited 13 patients with interictal AM and 15 patients with nonallodynic migraine (NA), and 30 healthy subjects (HS). BRs were obtained using paired pulses delivered at the interstimulus interval (ISI) of 150, 300, and 500 ms. The ratio of the area in the R2 of the second to R2 of the first shock was measured for each ISI. PVEP were recorded with 2 spatial frequencies (0.5 and 4.0 cpd) and 2 low and high contrasts (29% and 98%, respectively). Amplitudes of P100 were measured. RESULTS: For BR, there were no significant differences in the ratio of the area of the R2 between the sides of stimulation, and the sides of headache. AM patients had less suppression of the R2 at the ISI of 150 and 300 ms when compared with the NA patients and HS. For PVEP, at 0.5, there were significant differences of amplitude between AM patients and HS, and between NA patients and HS in low and high contrast. At 4.0 cpd, there were significant differences of amplitude between AM patients and HS in low contrast, and between AM patients and HS, and NA patients and HS in high contrast. In AM patients, there was a significant difference of amplitude ratio between 0.5 and 4.0 cpd. Conclusions.-Our BR and PVEP study showed that migraine patients exhibiting allodynia may show central sensitization of brainstem trigeminal neuron and have contrast modulating dysfunction during the cortical visual processing of striate and extrastriate on visual cortex in-between attacks.

Adult↗
PubMedDate not supplied

Comparison of 4 blood storage methods in a protocol for equine pre-operative autologous donation.

OBJECTIVE: To compare viability of equine whole blood stored by 4 different methods, and to establish optimal storage protocols for an equine autologous blood donation program. STUDY DESIGN: In vitro study of stored equine whole blood. Animals- Six healthy adult horses. METHODS: Blood from each horse was collected into 4 different containers: glass bottles containing acid-citrate-dextrose solution (ACD), plastic bags containing ACD, citrate-phosphate-dextrose (CPD), and CPD with supplemental adenine (CPDA-1). Blood was stored for 5 weeks and sampled at 2-day intervals. Standard hematologic and biochemical variables were evaluated, and adenosine-5-triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) concentrations were measured and normalized to total hemoglobin content. RESULTS: Plasma hemoglobin, % hemolysis, lactate, potassium, ammonia, and lactate dehydrogenase (LDH) increased, whereas glucose concentration and pH decreased in all stored blood over 5 weeks. There was a temporal increase in hemolysis with all storage methods, but the increase was greatest in glass bottles. Lactate and ammonia were highest in CPD and CPDA-1 samples, indicating more active red blood cell (RBC) metabolism. 2,3-DPG concentrations decreased during storage, but were optimally preserved with CPDA-1. ATP concentrations were significantly higher for blood stored in CPDA-1, and were lowest in glass bottles. CONCLUSIONS: Hematologic and biochemical values measured for blood stored in CPDA-1 are suggestive of improved RBC viability compared with other storage methods. With the exception of ATP, results from stored equine blood were similar to those reported for other species. CLINICAL RELEVANCE: Commercial CPDA-1 bags appear to be the optimal storage method for equine whole blood.

2,3-Diphosphoglycerate↗
PubMed2005

Automation of the glycerolization of red blood cells with the high-separation bowl in the Haemonetics ACP 215 instrument.

BACKGROUND: The FDA has approved a closed-system red blood cell (RBC) glycerolization procedure with the ACP 215 (Haemonetics), which requires a centrifuge to prepare RBCs before and after glycerolization. In the study reported here, the Haemonetics high-separation bowl was evaluated in an attempt to automate these two concentration steps. STUDY DESIGN AND METHODS: Ten units of nonleukoreduced citrate phosphate dextrose (CPD)-anticoagulated whole blood were stored at 4 degrees C for 2 to 6 days before glycerolization and freezing as nonrejuvenated RBCs. Twenty-five units of nonleukoreduced CPD whole blood were stored at 4 degrees C for 2 to 8 days and then biochemically treated with a solution containing pyruvate, inosine, phosphate, and adenine (PIPA) before glycerolization and freezing as indated-rejuvenated RBC. Twenty units of leukoreduced CPD and AS-1 RBCs were stored at 4 degrees C for a mean of 48 days and treated with PIPA solution before glycerolization and freezing as outdated-rejuvenated RBCs. The glycerolized RBCs were frozen for at least 2 weeks at -80 degrees C, deglycerolized in the Haemonetics ACP 215 with the 325-mL bowl, and stored in AS-3 at 4 degrees C for 21 days. RESULTS: It took approximately 50 minutes to glycerolize the nonrejuvenated and rejuvenated RBCs. After freezing, deglycerolization, and postwash storage at 4 degrees C in AS-3 for 2 weeks, the quality was similar to that of RBCs processed by the current FDA-approved method. CONCLUSION: Processing time and need for technical expertise were significantly reduced with the completely automated functionally closed glycerolization procedure with the high-separation bowl in the Haemonetics ACP 215 instrument.

2,3-Diphosphoglycerate↗
PubMed1992

Clinical effects of simultaneous ultrasonic scaling and subgingival irrigation with chlorhexidine. Mediating influence of periodontal probing depth.

The clinical and microbial effects of a single episode of simultaneous ultrasonic scaling and subgingival irrigation with chlorhexidine (CHX) were studied as a function of clinical probing depth in patients with adult periodontitis. 60 patients were randomly assigned to receive subgingival irrigation under cavitation with either sterile water or 0.12% CHX delivered through the tip of an ultrasonically activated scaler as part of initial periodontal therapy in a double-blind study design. 3 periodontal sites were randomly selected for examination from each patient on the basis of clinical probing depth, with 1 site being selected within each of the following ranges: 1-3 mm, 4-6 mm, and 7-9 mm. Pretreatment and post-treatment (days 14 and 28) clinical assessments included a plaque index (PI), gingival index (GI), and clinical probing depth (CPD). Subgingival specimens also were collected from 1-3 mm and 4-6 mm sites on a random subset of patients (15 per group). Plaque counts of spirochetes and motile organisms were made by darkfield microscopy. Significant reductions in PI, GI, and CPD were observed among all sites within both treatment groups at 14 and 28 days post-treatment. CHX irrigation resulted in a significantly greater reduction in CPD than did water among sites initially probing 4-6 mm at both 14 and 28 days post-treatment (25% versus 13% and 31% versus 18%, respectively). Spirochete counts were modestly but nonsignificantly reduced at 14 days post-treatment among sites 4-6 mm within both treatment groups. These results suggest that subgingival irrigation with CHX during ultrasonic scaling provides differential clinical benefits that are site-dependent.

Adult↗