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PubMed2002

Diurnal variations of glomerular filtration rate and albuminuria in diabetic nephropathy.

BACKGROUND: The aim of our study was to evaluate the diurnal variation in glomerular filtration rate (GFR), and the potential mechanisms responsible for such variations in GFR and albuminuria in diabetic nephropathy. METHODS: In three 24-hour urine samples, divided into a night- and daytime portion, diurnal variation in albuminuria (ELISA) was assessed. Furthermore, during recumbency changes in albuminuria, GFR (51Cr-EDTA plasma clearance) and arterial blood pressure (TM2420) from nighttime (00:00 to 05:00 hours) to subsequent daytime (08:00 to 13:00 hours) were examined in 20 type 1 diabetic patients with diabetic nephropathy. RESULTS: The 24-hour urine collections showed an average rise in albuminuria from night- to daytime of 51% (95% CI; 16 to 95; P < 0.01). During recumbency a non-significant rise was recorded from night- to daytime in albuminuria (22%, -8 to 61, P=0.15), simultaneously with an increase in GFR of 9.0% (3.4 to 14.5, P < 0.005) and mean arterial blood pressure (MABP) of 8.0% (4.3 to 11.7, P < 0.0001). No diurnal variation in fractional clearance of albumin was found. Significant associations between MABP and albuminuria were demonstrated during night- (R2=0.50; P < 0.001) and daytime (R2=0.48; P < 0.005). A linear regression analysis between diurnal variations in MABP and GFR showed that an increase in MABP (of 10%) from night- to daytime was associated with a significant increase in GFR (of 8.0%, 0.2 to 4.1, P < 0.02). CONCLUSIONS: Our study revealed diurnal variations in GFR, albuminuria and MABP in diabetic nephropathy, with lowest values during sleep at night. The observed diurnal variation in albuminuria seems to be explained partly by mechanisms related to orthostasis, and partly by the diurnal variation in GFR and serum albumin concentration. The diurnal variation of blood pressure seems to play a role for the diurnal changes in GFR and albuminuria.

Adolescent↗

PubMed1991

Circadian variation in platelet imipramine binding during the day in healthy subjects.

Platelet tritiated imipramine binding values in healthy controls vary considerably from study to study. A possible contributor to such variation might be a circadian rhythm affecting binding, although previous studies of this have been contradictory. Platelet imipramine binding was examined in 12 healthy, medication-free subjects studied at 8 a. m., 11 a. m., 4 p. m., and 10 p. m. during one day. Imipramine binding was determined on platelet membranes, using 0.8-8 nM 3H-imipramine, and nonspecific binding was defined by 50 microM desipramine. All samples from a given individual were assayed simultaneously. The intra-assay coefficient of variation was 6.3 percent. There was no evidence of significant differences in binding capacity or affinity (Bmax or Kd) at different times of day. Circadian variation was explored using COSINOR analysis (DeMet et al., 1989). There was no evidence of circadian variation in binding using this model, even when only the variable portion of binding was considered for each individual. Intraindividual variation in binding was substantial, with a mean coefficient of variation of 29 percent for Bmax and 38 percent for Kd. The possible basis of this variation is unclear, but may reflect the presence of "occult" binding sites in the membrane, or the effect of endogenous modulators of binding. The interrelationship of Bmax and Kd may also be a factor. It was considered that low-affinity binding did not account for a significant part of the variation in Kd in this assay. The utility of imipramine binding as a biological marker of depression may be limited by such levels of intraindividual variation in binding parameters.

Adult↗

PubMed1976

Biologic and analytic components of variation of concentration values of selected serum proteins.

The magnitude and statistical significance of the various biologic and analytic sources of variation of the serum concentration values of seven proteins: albumin, alpha1-antitrypsin, transferrin, orosomucoid, IgG, IgM, and IgA, were evaluated in 12 healthy subjects. Blood specimens were obtained at 0800 h, 1100 h, and 1400 h on one particular day. The analytic error was partitioned into pre-instrumental and instrumental components; the biologic variation was separated into inter-subject variation of mean levels and intra-individual within-day variation. The mean levels of the subjects differed significantly for all seven proteins studied. For the group as a whole there were no consistent diurnal variations of significance. However, for all the proteins, except for IgM, significant individual within-day biologic fluctuations were noted. The within-day biologic variation was smaller than the total analytic variation for transferrin, IgG, orosomucoid, and IgM. When the total analytic variation was separated into pre-instrumental and instrumental components, it was found that the pre-instrumental sources of variation were of a relatively greater magnitude for albumin, IgG, IgA, alpha1-antitrypsin, and IgM.

Adult↗

PubMed2002

Geographic variations in breast cancer survival among older women: implications for quality of breast cancer care.

BACKGROUND: Breast cancer care, such as utilization of screening procedures and types of treatment received, varies substantially by geographic region of the United States. However, little is known about variations in survival with breast cancer. METHODS: We examined breast cancer incidence, survival, and mortality in the 66 health service areas covered by the Surveillance, Epidemiology, and End Results (SEER) program for women aged 65 and older at diagnosis. Incidence and survival data were derived from SEER, while breast cancer mortality data were from Vital Statistics data. RESULTS: There was considerable variation in breast cancer survival among the 66 health service areas (chi2 = 202.7, p <.0001). There was also significant variation in incidence and mortality from breast cancer. In a partial correlation weighted for the size of the health service area, both incidence (r =.812) and percent 5-year survival (r = -.587) correlate with mortality. In a Poisson regression analysis, the combination of variation in incidence and variation in survival explains 90.9% of the variation in mortality. CONCLUSIONS: There is considerable geographic variation in survival from breast cancer among older women, and this contributes to variation in breast cancer mortality. Geographic variations in breast cancer mortality should diminish as the quality of breast cancer care becomes more standardized.

Aged↗

PubMed1997

Short-term keratometric variation in the human eye.

Previous studies of corneal and keratometric variation used statistical methods that were not entirely satisfactory. For the first time, proper multivariate statistical methods are applied to evaluate short-term keratometric variation in human eyes. Keratometric variation is represented graphically by means of stereo-pair scatter plots, ellipsoidal confidence regions for mean dioptric power, and meridional profiles of variation. There is great variability in the keratometric variation displayed by different subjects, although most subjects exhibit greatest variation in the vertical meridian of the eye on most of the measuring occasions. Variance-covariance matrices based on vector h are given. In some cases keratometric variation approaches neutral uniform variation. In many of the subjects, mean keratometric measurements change from morning to afternoon, usually showing an increase in curvature later in the day. Physical activity may increase keratometric variation and mean curvature.

Adult↗

PubMed2001

Implications of arterial pressure variation in patients in the intensive care unit.

Positive-pressure ventilation alters stroke volume by transiently increasing intrathoracic pressure and thereby decreasing preload. This phasic variation in stroke volume results in a cyclic fluctuation in arterial pressure with a phase length equal to the respiratory rate. Measuring ventilation-induced arterial pressure variation allows the clinician to predict the cardiovascular response to changes in intravascular volume status. Thus, one may predict preload responsiveness because the greater the amount of ventilation-associated arterial pressure variation, the greater the patient's preload responsiveness. This variation in arterial pressure can been defined as a variation in either systolic pressure or pulse pressure. Although pulse pressure gives a clearer signal, systolic pressure variation may be easier to measure bedside without invasive hemodynamic monitoring. Newer methods of quantifying this arterial pressure variation include the respiratory systolic variation test, which can performed without an apneic baseline, and the pulse pressure variation, a potentially more accurate measure of preload responsiveness.

Blood Pressure↗

PubMed1992

Intra-patient variation between breast cancer axillary lymph node metastases using quantifiable features.

The intra-patient variations of some clinically relevant quantifiable features, between axillary lymph node metastases were evaluated in 44 breast cancer patients. In all lymph node metastases detected (range 2-33 per patient), the mitotic figures were counted, the volume percentage epithelium was assessed and the mean nuclear area was measured. The intra-patient variation for each quantifiable feature was expressed by the coefficient of variation (CV). Since the measurement techniques used introduce a certain, well known variation themselves because of sampling and measurement errors, the CVs found had to be greater than methodological tolerance limits (established in previous studies) to be interpreted as indicating biological variation. The CVs exceeded the methodological tolerance limits in 86% of the cases for the mitotic count, in 48% of the cases for the volume percentage epithelium, and in 47% of the cases for the mean nuclear area. This indicated that in these cases, the variation found in the quantifiable features could not be explained by sampling or measurement errors and should be regarded as real biological variation. Furthermore, the variation in the quantifiable features studied showed a significant positive correlation with the number of lymph node metastases. Thus, there may be considerable intra-patient variation in quantifiable features between axillary lymph node metastases in breast cancer. This may indicate that these lymph node metastases originate independently from different clones within the primary tumour, that they are independently formed in different stages of tumour development, or that they, as an expression of intrinsic tumour heterogeneity, may develop in different directions from the start.

Axilla↗

PubMed2006

Experimental and model analyses of the effects of competition on individual size variation in wood frog (Rana sylvatica) tadpoles.

1. Size variation is a ubiquitous feature of animal populations and is predicted to strongly influence species abundance and dynamics; however, the factors that determine size variation are not well understood. 2. In a mesocosm experiment, we found that the relationship between mean and variation in wood frog (Rana sylvatica) tadpole size is qualitatively different at different levels of competition created by manipulating resource supply rates or tadpole density. At low competition, relative size variation (as measured by the coefficient of variation) decreased as a function of mean size, while at high competition, relative size variation increased. Therefore, increased competition magnified differences in individual performance as measured by growth rate. 3. A model was developed to estimate the contribution of size-dependent factors (i.e. based on size alone) and size-independent factors (i.e. resulting from persistent inherent phenotypic differences other than size that affect growth) on the empirical patterns. 4. Model analysis of the low competition treatment indicated that size-dependent factors alone can describe the relationship between mean size and size variation. To fit the data, the size scaling exponent that describes the dependence of growth rate on size was determined. The estimated value, 0-83, is in the range of that derived from physiological studies. 5. At high competition, the model analysis indicated that individual differences in foraging ability, either size-based or due to inherent phenotypic differences (size-independent factors), were much more pronounced than at low competition. The model was used to quantify the changes in size-dependent or size-independent factors that underlie the effect of competition on size-variation. In contrast to results at low competition, parameters derived from physiological studies could not be used to describe the observed relationships. 6. Our experimental and model results elucidate the role of size-dependent and size-independent factors in the development of size variation, and highlight and quantify the context dependence of individual (intrapopulation) differences in competitive abilities.

Animals↗

PubMed1997

The effect of carotid sinus denervation on fetal heart rate variation in normoxia, hypoxia and post-hypoxia in fetal sheep.

OBJECTIVE: To investigate whether carotid sinus nerve reflexes are linked to the increase in heart rate variation in acute (one hour) hypoxia in late gestation fetal sheep DESIGN: Comparison of short term variation between intact and carotid sinus denervated fetuses in normoxia, hypoxia and post-hypoxia. SUBJECTS: Sixteen chronically catheterised pregnant sheep in late gestation. RESULTS: There was no significant difference in short term variation between intact and denervated fetuses in normoxia. In intact fetuses short term variation increased significantly in hypoxia. In denervated fetuses it tended to increase in hypoxia, but this was not statistically significant. During the post-hypoxia period, short term variation increased significantly in denervated fetuses, although at this time it was decreasing in intact fetuses. When the decrease in pH was small intact fetuses showed a significantly greater increase in short term variation than denervated fetuses in hypoxia. In contrast, short term variation increased similarly in both groups when the pH decrease was greater (> 0.03 in early hypoxia and > 0.05 in late hypoxia). CONCLUSIONS: Carotid sinus nerve reflexes have an important influence on heart rate variation in hypoxia and post-hypoxia. It appears that other mechanisms (e.g. a rise in circulating catecholamines) are linked to an increase in heart rate variation when mild acidemia occurs in hypoxia.

Animals↗

PubMed1995

Circadian variation of heart rate variability in postinfarction patients with and without life-threatening ventricular tachyarrhythmias.

INTRODUCTION: Determination of heart rate variability (HRV) is widely used for noninvasive assessment of cardiac autonomic tone. A decreased HRV is associated with an increased mortality in patients surviving an acute myocardial infarction. There are, however, only sparse data about the circadian variation of different components of HRV that may be linked to the well-known circadian fluctuations in the occurrence of sudden death. In addition, the potential prognostic impact of circadian variations of HRV has not been examined. METHODS AND RESULTS: The present study compared the circadian variation of HRV from 14 postinfarction patients who had survived at least one episode of out-of-hospital cardiac arrest (cardiac arrest group) with that of 14 age- and sex-matched patients without a history of malignant arrhythmias after their index infarct (control group). Several time- and frequency-domain measures of HRV were assessed from 24-hour Holter recordings. Circadian variations of high- (HF), low- (LF), and total-frequency (TF) components were determined by calculating for each parameter the hourly difference from the day's mean. The average of these differences was calculated for every hour as well as for predefined day and night periods. There was no significant difference between the two groups with regard to HRV indices that predominantly reflect vagal tone, such as SDNN (78 +/- 25 vs 96 +/- 24 msec), pNN50 (2.7% +/- 4.6% vs 4.9% +/- 4.2%), or HF (6.3 +/- 3.0 vs 7.8 +/- 3.2 msec; cardiac arrest vs control group). There was also no significant difference in the circadian variation of LF or TF between the two groups during daytime and nighttime. However, a significant difference in circadian variation of HF was found during daytime (0.02 +/- 0.5 vs -0.6 +/- 0.5 msec; P = 0.006) and nighttime (0.19 +/- 0.64 vs 1.5 +/- 0.75 msec; P = 0.0002). In cardiac arrest survivors, there was no difference in the mean deviation of HF between the day- and the nighttime periods. CONCLUSIONS: These results show an almost complete abolition in circadian variation of parasympathetic tone in postinfarction patients surviving an episode of out-of-hospital cardiac arrest, whereas circadian variation of sympathetic tone is comparable to that of postinfarction patients without arrhythmic episodes. These findings indicate that determination of diurnal variation of HRV may add to the prognostic value of HRV with respect to identifying patients at high risk of sudden death.

Autonomic Nervous System↗

PubMed2004

Within-individual variation in bullfrog vocalizations: implications for a vocally mediated social recognition system.

Acoustic signals provide a basis for social recognition in a wide range of animals. Few studies, however, have attempted to relate the patterns of individual variation in signals to behavioral discrimination thresholds used by receivers to discriminate among individuals. North American bullfrogs (Rana catesbeiana) discriminate among familiar and unfamiliar individuals based on individual variation in advertisement calls. The sources, patterns, and magnitudes of variation in eight acoustic properties of multiple-note advertisement calls were examined to understand how patterns of within-individual variation might either constrain, or provide additional cues for, vocal recognition. Six of eight acoustic properties exhibited significant note-to-note variation within multiple-note calls. Despite this source of within-individual variation, all call properties varied significantly among individuals, and multivariate analyses indicated that call notes were individually distinct. Fine-temporal and spectral call properties exhibited less within-individual variation compared to gross-temporal properties and contributed most toward statistically distinguishing among individuals. Among-individual differences in the patterns of within-individual variation in some properties suggest that within-individual variation could also function as a recognition cue. The distributions of among-individual and within-individual differences were used to generate hypotheses about the expected behavioral discrimination thresholds of receivers.

Animal Communication↗

PubMed2000

Circadian variation in witnessed out of hospital cardiac arrest.

OBJECTIVES: To examine the effect on circadian variation of out of hospital cardiac arrest according to the underlying aetiology and presenting rhythm of arrest, and to explore strategies that might help to improve survival outcome using circadian variation. DESIGN: Population based retrospective study. SETTING: County of Nottinghamshire with a total population of 993 914 and an area of 2183 km(2). SUBJECTS: Between 1 January 1991 and 3 December 1994, all witnessed cardiac arrests attended by the Nottinghamshire Ambulance Service, of which 1196 patients had a cardiac cause for their arrest (ICD, 9th revision, codes 390-414 and 420-429) and 339 had a non-cardiac cause. RESULTS: The circadian variation of the cardiac cases was not significantly different from that of non-cardiac cases (p = 0.587), even when adjusted for age, sex, or presenting rhythm of arrest. For cardiac cases, the circadian variation of those who presented with ventricular fibrillation was significantly different from those presenting with a rhythm other than ventricular fibrillation (p = 0.005), but was similar to the circadian variation of bystander cardiopulmonary resuscitation (p = 0.306) and survivors (p = 0.542). Ambulance response time was also found to have a circadian variation. CONCLUSIONS: There is a common circadian variation of out of hospital cardiac arrest, irrespective of underlying aetiology, where the presenting rhythm is other than ventricular fibrillation. This is different from the circadian variation of cases of cardiac aetiology presenting with ventricular fibrillation. The circadian variation of ventricular fibrillation, and consequently survival, may be affected by the availability of bystander cardiopulmonary resuscitation and the speed of ambulance response.

Aged↗

PubMed1995

Components of small area variation in death rates: a method applied to data from Sweden.

STUDY OBJECTIVES: The study aimed to develop and evaluate a method for small area analysis of different non-random components of the variation in death rates. The method was applied to incidence and mortality data for selected malignant neoplasms in 26 administrative health areas in Sweden. DESIGN: Variation in mortality and incidence rates for malignant neoplasms of the trachea, bronchus, and lung; colon; rectum; and cervix uteri in the 26 health areas were analysed after standardisation for age. In addition, the systematic and random components of variance were estimated. The systematic component of variance in mortality was divided into two additive components-one component was dependent on the variation in the corresponding incidence rates and the other remained after adjustment for incidence. SETTING AND PARTICIPANT: All cases diagnosed between 1972 and 1983 and all deaths between 1974 and 1985 for selected malignant neoplasms in Swedish citizens and other residents in Sweden, aged between 0 and 64 years, were analysed. MAIN RESULTS: Much of the observed variation in mortality was explained by the estimated random variation. For malignant neoplasms of the trachea, bronchus, and lung the systematic variation in mortality was mainly explained by the variation in incidence. For cancer of the cervix uteri, alone, there was significant systematic variation of moderate magnitude that was not explained by the incidence rates. CONCLUSIONS: These methods made it possible to divide the observed variance in mortality into different components. Random effects and variance in incidence rates were found to be of great importance when analysing the variance in death rates between health areas. By studying different systematic components of variation it is possible to identify fields for in depth studies on the quality of prevention and treatment.

Adolescent↗

PubMed2006

Seasonal variation in blood pressure of patients on continuous ambulatory peritoneal dialysis.

BACKGROUND: A seasonal variation in blood pressure (BP) has been observed in hemodialysis and renal transplant patients. However, this phenomenon in continuous ambulatory peritoneal dialysis (CAPD) patients, whose hemodynamics are different from hemodialysis patients, has not been reported before. In addition, the contribution of extracellular water (ECW) in the seasonal variation in BP is not clear. METHODS: All stable CAPD patients (n = 122) dialyzed in a single center from January 1, 2003 to December 12, 2004 were studied. Systolic blood pressure (SBP), diastolic blood pressure (DBP), weight and ECW (by bioimpedance analysis) were measured in every patient. Climatic data were obtained from the Beijing Weather Bureau. These data were pooled together and grouped according to the calendar month. RESULTS: In general, an apparent seasonal variation in BP was observed in CAPD patients. BP began to decrease from spring and reached the lowest level in summer, then increased from autumn and reached its peak in winter. The seasonal variation in BP in male patients was similar to that in female patients, but in comparison to non-diabetic patients there was no apparent seasonal variation in the BP of diabetic patients. SBP and DBP negatively correlated with the average atmospheric temperature (r = -0.768, p < 0.001 and r = -0.764, p < 0.001, respectively). BP also negatively correlated with rainfall and humidity, but this correlation disappeared when temperature was controlled in partial correlation analysis. Weight and ECW fluctuated throughout the year but showed no seasonal variation. CONCLUSION: On the whole there was an apparent seasonal variation in blood pressure in CAPD patients. As opposed to non-diabetic patients, there was no apparent seasonal variation in BP in diabetic patients. The seasonal variation in BP was influenced more by temperature than rainfall and humidity, and the change in ECW was not seasonal, suggesting that other mechanisms such as total peripheral resistance might play a more important role in this phenomenon.

Aged↗

PubMed1992

Geographic patterns of chromosomal variation in South American marsh rats, Holochilus brasiliensis and H. vulpinus.

Karyotypes were prepared from 146 individuals, representing nine populations evenly spaced along a 2,000-km north-south transect in Paraguay and Argentina, to determine the nature, extent, and pattern of chromosomal variation in Holochilus brasiliensis chacarius and H. vulpinus. Two distinct patterns of chromosomal variation characterized these two species. In H. brasiliensis, the diploid number (2n) ranged from 48 to 56 and the nombre fondamental (NF) from 57 to 63. Four classes of chromosomal variation were found in populations of H. brasiliensis: whole-arm Robertsonian (Rb) translocations, including Rb changes with monobrachial homology, variation in the number and kind of supernumerary (B) chromosomes, centromeric rearrangements (putative pericentric inversions), and variation in the amount of euchromatin. The amount of structural variation was uniformly high in all populations of H. brasiliensis sampled, and all rearrangements appeared to be in Hardy-Weinberg proportions, corroborating the hypothesis that chromosomal rearrangements are not strongly underdominant in this species. In H. vulpinus, 2n ranged from 35 to 39 and NF from 57 to 61. Two classes of variation were found in this species: variation in the number, but not the kind, of supernumerary chromosomes and variation in the amount of euchromatin.

Animals↗

PubMed1994

Abolition of cyclic flow variations in stenosed, endothelium-injured coronary arteries in nonhuman primates with a peptide fragment (VCL) derived from human plasma von Willebrand factor-glycoprotein Ib binding domain.

BACKGROUND: Platelets play an important role in the pathophysiology of acute coronary syndromes. The interaction between the platelet glycoprotein Ib receptor and von Willebrand factor is a critical event allowing platelet adhesion and aggregation and subsequent thrombus formation in vessels with high shear rates and damaged endothelium. Therefore, we tested the hypotheses that VCL, an antagonist of von Willebrand-glycoprotein Ib binding domain, (1) attenuates/abolishes cyclic flow variations in stenosed, endothelium-injured coronary arteries in nonhuman primates and (2) reduces botrocetin-induced platelet aggregation in vitro after intravenous in vivo administration. METHODS AND RESULTS: Cyclic flow variations were established in anesthetized, open-chest baboons (n = 18). The baboons were divided into three groups. One group (n = 8) received a bolus of VCL (4 mg/kg IV) followed by an infusion (6 mg.kg-1.h-1) for 90 minutes (schedule A). Another group (n = 6) received a 2-mg/kg bolus followed by an infusion of 3 mg.kg-1.h-1 for 90 minutes (schedule B). The third group received a placebo infusion of normal saline. Under dosing schedule A, cyclic flow variations were abolished in 7 of 8 baboons after 33 +/- 18 minutes and markedly attenuated in 1. The frequency of cyclic flow variations fell from 18 +/- 9.4 per hour during the control period to 1 +/- 2.5 per hour after VCL infusion, P < .002. After cessation of infusion, cyclic flow variations remained abolished in 5 of 7 animals for > 3 hours and returned in 2 of 7 after 2 to 2.5 hours. Under schedule B, cyclic flow variations were abolished in 3 of 6 baboons and markedly reduced in the remainder. The number of cyclic flow variations fell from 17 +/- 4.8 per hour during the control period to 5 +/- 4.9 per hour after the VCL infusion, P < .001. The cyclic flow variations returned spontaneously at 38 +/- 40 minutes under this dosing schedule. Placebo infusion of saline had no effect on cyclic flow frequency or severity. VCL administration was associated with slight prolongation in bleeding time and a reduction in botrocetin-induced platelet aggregation. The bleeding time increased from a control time of 88 +/- 32 to 276 +/- 204 seconds, P < .03, and from 142 +/- 28 to 176 +/- 36 seconds, P = .056, for schedules A and B, respectively. VCL decreased platelet aggregation in response to botrocetin (20 micrograms/mL), from a control value of 66 +/- 30.3 to 33 +/- 31.3 omega, P < .05, and from 64 +/- 23.5 to 46 +/- 15.8 omega, P = .006, for dosing schedules A and B, respectively. CONCLUSIONS: Therefore, administration of a peptide fragment corresponding to von Willebrand-glycoprotein Ib binding domain (1) is effective in abolishing cyclic flow variations in stenosed, endothelium-injured coronary arteries and (2) reduces platelet aggregation in vivo in response to botrocetin in nonhuman primates.

Animals↗

PubMed2006

Variations in arterial blood pressure and photoplethysmography during mechanical ventilation.

We analyzed ventilation-induced changes in arterial blood pressure and photoplethysmography from waveforms obtained by monitoring 57 patients in the operating room and intensive care unit. Analysis of systolic and pulse pressure variations during positive pressure ventilation, DeltaUp, DeltaDown, and changes in the preejection period on both arterial and photoplethysmographic waveforms were possible in 49 (86%) patients. The pulse pressure variation and preejection period were similar when calculated using both arterial blood pressure and photoplethysmography, whereas the other variables were different. Photoplethysmographic pulse variation >9% identified patients with arterial pulse pressure variation >13% (area under ROC curve = 0.85) or DeltaDown >5 mm Hg (area under ROC curve = 0.85). In hypotensive patients, photoplethysmographic pulse variation >9% remained the best threshold value (pulse pressure variation >13%: area under ROC curve = 0.90; DeltaDown >5 mm Hg: area under ROC curve = 0.93) for predicting fluid responsiveness. In conclusion, this study showed that pulse variations observed in the arterial pressure waveform and photoplethysmogram are similiar in response to positive pressure ventilation. Furthermore, photoplethysmographic pulse variation > 9% identifies patients with ventilation-induced arterial blood pressure variation that is likely to respond to fluid administration.

Adult↗

PubMed1993

Diurnal variation of plasma minerals and trace elements in a group of Japanese male adults.

When the nutritional status of minerals and essential trace elements is assessed by their levels in plasma, intra-individual variation in the measured values, particularly diurnal variation, must be considered. In this paper, concentrations of nine elements (Na, Mg, P, K, Ca, Fe, Cu, Zn, and Se) in plasma collected 7 times in a 24-h period from 10 healthy Japanese adults were measured with hemoglobin and plasma concentrations of proteins (total protein, albumin, retinol binding protein (RBP), ceruloplasmin, and transferrin), total cholesterol, and cortisol. Then the pattern of diurnal variation in, and the interrelationships among, these parameters were clarified in subjects who consumed an ordinary meal. Significant diurnal variation examined by two-way analysis of variance (variations due to subject and sampling time) was found for Zn, RBP, and cortisol. Plasma Zn level was higher in the forenoon samples than in those taken in the afternoon. The pattern of diurnal variation found for cortisol was similar to, but slightly different from, that for Zn. The correlation coefficient between Zn and cortisol was significant (r = 0.555) using the standardized values for individuals, and in the result of multiple regression analysis, cortisol level was selected as the significant explanatory factor for Zn variation; however, the sampling time was the most significant factor. For other elements besides Zn, no significant diurnal variation was found. Moreover, no meaningful factors were selected for variations of those elements in the result of multiple regression analysis. These results indicate that, in assessing Zn nutriture with its plasma levels, it is necessary to unify the sampling time.

Adult↗