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PubMed2002

Pattern ERG and VEP maturation in schoolchildren.

OBJECTIVE: The maturation of the visual system has been studied with pattern electroretinograms (PERG) and pattern visual evoked potentials (PVEP) mostly in children under the age of 6 years. To address the question of maturation of the visual system in childhood and adolescence we investigated age-dependent PERG and PVEP changes in children aged 7-18 years. METHODS: PERG were recorded with skin electrodes attached to the lower eyelid, and PVEP were recorded with 5 electrodes. Visual stimuli, consisting of pattern-reversal 50' checks to full-field and to half-field stimulation, were applied to obtain macular (N70, P100, N145) and paramacular waves (P80, N105, N135). RESULTS: We found an age-dependent decrease (linear regression P<0.05) of PERG P50 amplitude and full-field PVEP P100 latency to monocular right and left eye stimulation, indicating central retinal and postretinal changes. In addition, waveform changes were found in responses to half-field stimulation. The paramacular wave N105 was typically enhanced in younger schoolchildren and diminished with age. The age-dependent decrease (linear regression P<0.01) of paramacular N105 amplitude indicated the increasing predominance of the macular structures of the visual system. CONCLUSIONS: Our findings suggest that central retinal and postretinal electrophysiological maturation persists throughout childhood. Age-dependent PVEP changes seem to correlate with the morphological and metabolic findings that maturation of the visual cortex continues until puberty and even later.

Adolescent↗

PubMed2000

Representation of accuracy in the dorsal premotor cortex.

The endpoint accuracy of a reaching movement strongly affects kinematics, particularly during the final phases of movement. However, where and how accuracy is represented in the central nervous system remains unknown. In this study, the discharge of 150 neurons located primarily in the dorsal premotor cortex (PMd), were recorded from monkeys performing an instructed delay, centre-out reaching task in which movement direction and target size were systematically varied. Linear regression analyses were used to assess the dependence of movement kinematics and cell discharge on target direction, size and tangential velocity (i.e. speed). The speed and timing of the movement were dependent on both direction and target size. Initially direction was the dominant predictor whilst target size became more important as the hand reached the target. A temporal multiple linear regression analysis found significant correlations with target size in 99 of 150 cells. The discharge of 134 cells was directionally tuned and 83 cells modulated with mean speed. Significant correlations of discharge with target size occurred throughout the task as did correlations with direction. However, correlations with direction preferentially occurred early in the task, prior to movement onset, whilst correlations with target size tended to occur late, well after movement onset. This temporal dependency of the firing in relationship to target direction and size mirrored that observed for the kinematics. We conclude that the discharge of PMd cells is highly correlated with the accuracy requirement of the movement. The timing of the correlations suggest that accuracy information is available for the planning and for the on-line control of endpoint accuracy.

Action Potentials↗

PubMed2001

Tapering off prednisolone and cyclosporin the first year after renal transplantation: the effect on glucose tolerance.

BACKGROUND: Glucose intolerance is an untoward side effect of some immunosuppressive and anti-hypertensive drugs. The primary aim of the present prospective observational study was to test the hypothesis that tapering off prednisolone and cyclosporin (CsA) the first year after transplantation may have beneficial effects on glucose tolerance in renal transplant recipients. METHODS: Ninety-one non-diabetic recipients were included, and 87 patients underwent a 75 g oral glucose tolerance test both 10 weeks and 1 year after renal transplantation. The change over time in 2-h blood glucose was compared with a number of variables potentially influencing glucose tolerance. RESULTS: The proportion of glucose intolerant recipients was reduced from 55 to 34% during the study. Univariate linear regression analysis showed a significant association between the reduction in daily prednisolone dose down to 5 mg and decline in blood glucose (P=0.001), whereas weight gain was associated with increasing blood glucose (P=0.031). Each 1-mg reduction of prednisolone dose leads to an estimated decline in 2-h blood glucose of 0.12 mmol/l based on the multiple linear regression model (P=0.003). Twelve out of 22 patients with post-transplant diabetes mellitus (PTDM) at baseline improved to normal or impaired glucose tolerance. Ten PTDM-subjects who remained diabetic 1 year after transplantation had lower serum insulin levels during the oral glucose challenge, and five patients treated with anti-diabetic drugs at baseline required hypoglycaemic drugs also at follow up. The decline in CsA level of 100 microg/l and the lower number of patients treated with beta-blockers at follow-up, did not alter glucose tolerance significantly. CONCLUSIONS: Tapering off prednisolone, but not CsA, significantly improves glucose tolerance during the first year after renal transplantation.

Adult↗

PubMed2000

Plasma RNA viral load predicts the rate of CD4 T cell decline and death in HIV-2-infected patients in West Africa.

OBJECTIVE: To examine whether the levels of plasma RNA and DNA provirus predict the rate of CD4 cell decline and patient death. DESIGN: Retrospective analysis of HIV-2 cohort subjects. METHODS: Fifty-two subjects were recruited between January 1991 and December 1992. HIV-2 RNA levels in plasma and DNA levels in peripheral blood mononuclear cells (PBMC) were measured using in-house quantitative PCR assays. The annual rate of CD4 cell decline was calculated using the least-squares method. The survival data on 31 December 1997 were used. RESULTS: The mean percentage of CD4 cells at baseline was 30.7 (SD, 9.5). In a linear regression model, the annual rate of CD4 cell decline was 1.76 CD4% faster for every increase in one log10 RNA copies/ml [95% confidence interval (CI), 0.81-2.7; P = 0.0006; r = 0.46; n = 52] and 1.76 CD4% faster for every increase in log10 DNA copies/10(5) PBMC (95% CI 0.46-3.1; P = 0.01; r = 0.33; n = 42). In a multiple linear regression model, RNA load was related to CD4 decline independently of DNA load (P = 0.02). The overall mortality rate was 7.29/100 person-years. In a Cox regression model, the hazard rate increased by 2.12 for each log10 increase in RNA load (95% CI, 1.3-3.5; P = 0.0023) but only by 1.09 for each log10 increase in DNA load (95% CI, 0.64-1.87; P = 0.8). CONCLUSION: This longitudinal study shows for the first time that a baseline HIV-2 RNA load predicts the rate of disease progression. HIV-2-infected patients with a high viral load may need to be treated as vigorously as HIV-1 patients.

Adolescent↗

PubMed1996

Changing from intensive anticoagulation to treatment with aspirin alone for coronary stents: the experience of one centre in the United Kingdom.

OBJECTIVE: To investigate whether an elective change in the anticoagulation protocol for patients with coronary stents affected clinical outcomes and length of hospital stay. DESIGN: Retrospective observational study of a consecutive series of patients treated with coronary stents over an 18 month period from April 1994 to October 1995. BACKGROUND: Intensive anticoagulation regimens are used in many UK centres to reduce the risk of coronary stent thrombosis. Recent data have called into question the necessity for full anticoagulation and favourable results have been reported with antiplatelet agents alone. The results from a tertiary referral centre were investigated during a period where an elective change in policy was made: an initial 70 patients were treated intensively with intravenous heparin and with warfarin and aspirin; subsequently 94 were treated with aspirin and deployment of a high pressure balloon only. METHODS: Review of case notes, angiograms, and a database of intervention procedures and telephone interview. Classic epidemiological techniques, as well as linear regression and logistic regression, were used to model the outcomes of major procedural complications and length of hospital stay. PATIENTS: 164 patients treated with 196 coronary stents. RESULTS: There were 22 (13.4%) major complications (coronary bypass grafting 11, subacute thrombosis 6, tamponade 2, myocardial infarction 1, death 2). With logistic regression, the risk of major complication was shown not to be affected by anticoagulation (relative risk (RR) 1.03; P = 0.97). Significant determinants of risk included acute vessel closure as an indication for stenting (RR = 80.6; P < 0.001) and sex (male: female RR = 0.19; P = 0.02). The median length of stay (LOS) was 5 days (1-45). Use of a linear regression model showed that anticoagulation added 4.5 days and a major complication added a further 4.5 days to a baseline length of stay of 3.2 days (R2 = 0.32; P < 0.001). CONCLUSION: This is a report of coronary stenting as part of usual clinical practice in one British tertiary referral centre. In this experience, treatment with aspirin alone is probably as safe as intensive anticoagulation, and has the benefit of reducing length of stay by more than 50% to 3.2 days in an uncomplicated case.

Anticoagulants↗

PubMed1994

Carotid baroreflex control of blood pressure and heart rate in men during dynamic exercise.

The degree of control of blood pressure (BP) and heart rate (HR) by arterial baroreflex during exercise is still controversial. We studied baroreflex control of BP and HR in seven normal young men by a noninvasive procedure employing a neck suction chamber that delivers pulsatile positive and negative pressures to the carotid sinus (CS). Pressures applied to the CS ranged from -80 to +60 Torr in steps of 20 Torr. Pressure stimuli were triggered by electrocardiogram R wave, and each pressure step was maintained for 20 s in a continuous sequence. One baroreflex-response curve was obtained during the last 3 min of each 6-min period of exercise. The four levels of upright (cycle) exercise were 60, 120, 180, and 240 W, the highest requiring approximately 75% of maximal O2 uptake. The sensitivity of the HR baroreflex response assessed by linear regression of HR vs. CS pressure (CSP) did not significantly decrease from rest (-0.09 +/- 0.053 beat/Torr) to 240 W (-0.06 +/- 0.025 beat/Torr). The BP above or below which CSP was increased or decreased by neck collar pressure was significantly increased from rest (76 +/- 6.5 Torr) to 240 W (111.2 +/- 4.0 Torr). The sensitivity of baroreflex response was assessed by linear regression of BP vs. CSP and was not significantly different from rest (-0.29 +/- 0.054 Torr/Torr) up to exercise at 240 W (-0.29 +/- 0.048 Torr/Torr). We conclude that mild to severe exercise does not reduce the gain of the CS reflex below resting values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

A simple and reliable method to calibrate respiratory magnetometers and Respitrace.

We present a simple and reliable method to calibrate respiratory magnetometers and Respitrace to infer respiratory volume changes. As in earlier methods, we assume two degrees of freedom in the chest wall and that volume displacement depends linearly on surface motion at the rib cage and abdomen. Because the area of the rib cage is larger, a given motion of its surface produces a greater lung volume change; therefore, the rib cage motion signal is given a larger gain before the two signals are added to estimate volume. In contrast to earlier methods, we use a "standard ratio" to weight relative gains of the rib cage and abdominal signals for all subjects rather than determining a gain ratio for each individual subject. Our procedure does not require subjects to perform the sometimes difficult isovolume maneuvers used in the calibration method of Konno and Mead (J. Appl. Physiol. 22: 407-422, 1967), does not require statistical computation used in the multiple-breath linear regression method, and does not produce the occasional substantial errors in gain ratio that may occur with the other methods. When magnetometers are used, the standard ratio is 4:1 (rib cage-to-abdomen); when Respitrace is used, the standard ratio is 2:1. In 11 subjects, calibration with standard ratios was as accurate as the isovolume and linear regression techniques. Accuracy during normal breathing was nearly always within 10% (median 2%), but occasional large errors occurred with both instruments.

Adult↗

PubMed1990

Early alterations of the baroreceptor control of heart rate in patients with acute myocardial infarction.

Experimental coronary occlusion is accompanied by an acute impairment of the baroreceptor-heart rate reflex. This study was planned to determine whether this impairment also occurs in humans. In 30 patients admitted to a coronary care unit for an anterior (n = 14) or inferior (n = 16) transmural myocardial infarction (MI), we measured 1) the increase in RR interval induced by stimulating carotid baroreceptors through progressive reductions in neck chamber pressure, 2) the increase in RR interval induced by stimulating arterial baroreceptors through intravenous boluses of phenylephrine, and 3) the reduction in RR interval induced by deactivating arterial baroreceptors through intravenous boluses of nitroglycerin. Measurements were performed 49.5 +/- 2.4 hours (mean +/- SEM) after the MI. The results were compared with those of five age-matched patients admitted to the coronary care unit for chest pain and found free from ischemic heart disease. The sensitivity of the carotid baroreceptor-heart rate reflex (slope of the linear regression of RR interval over neck pressure changes) was markedly less in MI than in control patients (3.8 +/- 0.5 vs. 5.9 +/- 0.6 msec/mm Hg, p less than 0.05), the reduction being similar in patients with anterior and inferior MI. This was the case also for the baroreflex sensitivity measured by the phenylephrine and the nitroglycerin methods (slope of the linear regression of RR interval over systolic blood pressure changes). However, 10.2 +/- 0.3 days later, the baroreflex sensitivity measured by all three methods increased significantly (p less than 0.05 or 0.01) and became similar to that of control subjects, which showed no significant change from the early to the late period after admission into the coronary care unit. Thus, MI is accompanied by an acute marked impairment of the baroreceptor control of the heart in humans, and this is the case both for an anterior and an inferior MI. The impairment is largely transient in nature, however, and a clear-cut recovery of the baroreflex can be seen a few days later.

Carotid Sinus↗

PubMed2001

Determination of NTx in second-morning urine: a proposal for the standardization of morning urine collection.

UNLABELLED: According to the instruction manual from the producer of kits for determining the levels of aminoterminal telopeptide of type I collagen of organic bone matrix (NTx), the time of the collection of second-morning urine is arbitrary, i.e., a patient can urinate anytime within the period from about 6 to 8:30 a.m. This time interval is within the period of change in the circadian rhythm of the NTx excretion (maximum excretion with transition into fast decrease of excretion). Therefore, we considered it appropriate to standardize the conditions for the collection of second-morning urine and proposed applying the so-called 2-hour morning urine NTx2 (from 6 to 8.00 a.m. after an overnight fast). We examined 48 female patients aged 33-65 years with primary or secondary osteopenia or osteoporosis (all patients had normal renal functions). In these patients we determined NTx (Osteomark, OSTEX, USA) in standardly used 24-hour urine (NTx24) and in the proposed 2-hour morning urine (NTx2). AIM OF THE STUDY: 1) To find a mathematical character for the dependence of values of dependent variable NTx2 on independent variable NTx24 and to evaluate the statistical significance of this dependence; 2) to compare the ratio of the widths of 95% confidence intervals (C. I.) for NTx2 and NTx24 in patients (index: IO) with the ratio of the widths of reference limits for NTx in arbitrary second-morning urine (NTx2ostex) and in 24-hour urine (NTx24ostex) in healthy women (index: IR); 3) to evaluate the proposed 2-hour urine for the determination of NTx. STATISTICAL ANALYSIS: Stochastic and deterministic linear regressive analysis. Index of 95% C. I., index of reference limits. RESULTS: A statistically significant (P < 0.01) regressive dependence (r2 = 0.781) was found between the values of NTx24 and NTx2. The index for the widths of reference limits (IR) was 1.5 times greater than the index for osteopenic and osteoporotic patients (IO), meaning that the scatter of the NTx2ostex values was greater than NTx2 in the proposed 2-hour urine. CONCLUSION: Based on the statistically significant linear regressive dependence between NTx24 and NTx2 values, it is possible to use the proposed 2-hour morning urine to determine NTx levels in women. The introduction of 2-hour morning urine NTx2 could decrease the fluctuation range of NTx values in repeated examinations and in comparison with the determination of NTx2ostex in a random second-morning urine sample could make its values more accurate.

Adult↗

PubMed2006

[Relationship between obstructive sleep apnea/hypopnea syndrome and insulin resistance].

OBJECTIVE: To investigate whether obstructive sleep apnea/hypopnea syndrome (OSAHS) is independently associated with insulin resistance (IR). METHODS: We recruited 60 male obese patients with OSAHS [OSAHS group, age (42.3 +/- 2.6) years, body mass index (BMI) (28.3 +/- 2.1) kg/m2, waist/hip ratio (WHR) 0.95 +/- 0.05], 60 male weight-matched obese patients without OSAHS [OB group, age (41.5 +/- 3.1) years, BMI (27.7 +/- 1.5) kg/m2, WHR 0.94 +/- 0.04] and 60 male normal weight subjects [NW group, age (41.8 +/- 2.4) years, BMI (22.6 +/- 1.9) kg/m2, WHR 0.86 +/- 0.05]. The subjects underwent polysomnography and OSAHS was defined as an apnea-hypopnea index (AHI) > or = 5. The systolic blood pressure and diastolic blood pressure were measured. IR was evaluated by fasting serum true insulin (TI) level and IR index based on the homeostasis model assessment method (HOMA-IR). In the OSAHS group, multiple linear regression was used with either TI or HOMA-IR as the dependent variable, and the corresponding set of independent variables included age, BMI, WHR, AHI and minimum oxygen saturation (MSpO2). RESULTS: After adjustment for age, BMI, and WHR, the OSAHS group was more insulin resistant, as indicated by the higher levels of TI and HOMA-IR. Multiple linear regression showed that the central obesity parameter (WHR) was the major determinant of IR of the OSAHS group, while sleep-disordered breathing parameters (AHI and MSpO2) were also independent determinants of IR of the group (TI: AHI P = 0.017, TI: MSpO2 P = 0.005; HOMA-IR: AHI P = 0.008, HOMA-IR: MSpO2 P = 0.003). CONCLUSION: OSAHS may be independently associated with IR.

Adult↗

PubMed1977

Portein kinases in brown adipose tissue of developing rats. State of activation of protein kinase during development and cold exposure and its relationship to adenosine 3':5'-monophosphate, lipolysis, and heat production.

The addition of norepinephrine to brown fat in vitro produced a dose-dependent increase in the protein kinase activity ratio (the ratio of activity assayed without cAMP to that assayed with cAMP) in extracts subsequently prepared in the presence of 0.5 M NaCl. The ratio was slightly increased by insulin. The effects of norepinephrine were potentiated by theophylline and reduced by propranolol. There was a significant linear regression between protein kinase activity ratio and the rate of glycerol release for ratios between 0.32 and 0.52. Higher activity ratios were associated with a slight but nonsignificant increase in glycerol release. The relationship between the protein kinase activity ratio and the concentration of cAMP in brown fat could be expressed by simple saturation kinetics. There was a significant linear regression between the reciprocal of the concentration of cAMP in the tissue and the reciprocal of the activity ratio over the whole range of observed values. Exposure of 1-month-old rats to cold increased the protein kinase activity ratio in their brown fat. This confirms that activation of protein kinase is involved in the physiological response of a tissue to a specific environmental stimulus. As the rat became fully adapted to the cold, the activity ratio declined. The protein kinase activity ratio in brown fat was low in late fetuses but greatly increased immediately after birth and remained high for the next 2 weeks. During this period the ratio was not further increased by the injection of norepinephrine but was reduced after chemical sympathectomy. The activity ratio in brown fat fell during the 3rd and 4th weeks after birth. At this time injection of norepinephrine increased the ratio whereas chemical sympathectomy had little effect. These observations confirm that the stimulation of the tissue by the sympathetic nerves results in an activation of protein kinase and reflect the reduced requirement for heat production in brown fat as the animals grow.

Adaptation, Physiological↗

PubMedDate not supplied

[Catch-up growth and final height in celiac disease].

BACKGROUND: Growth retardation resulting from celiac disease diagnosed in infancy or in early childhood is remediable after introduction of a gluten-free diet. The aim of this study was to evaluate long-term growth, catch-up growth and final height in a group of treated patients with celiac disease. METHODS: The study population consisted of 35 patients (13 M, 22 F) with typical celiac disease. Age at diagnosis was 1.17 (+/- 0.69) years. For each patient, the standard deviation score (SDS) and centile of height at diagnosis, target height and final height were elaborated, and linear regression and correlations between SDS of final height and age at diagnosis, SDS of height at diagnosis and SDS of target height, respectively, were calculated. RESULTS: At diagnosis patients had a general tendency to short stature: mean height was 81.8 cm +/- 22.9 cm (SDS -0.75 +/- 1.61), while target height was 164.3 cm +/- 13.5 cm (SDS -0.14 +/- 1.04) and final height 169.2 cm +/- 7.7 cm (SDS 0.41 +/- 1.04). Linear regression and correlations between SDS of final height and age at diagnosis, SDS of height at diagnosis and SDS of target height, respectively, proved nonsignificant. CONCLUSIONS: Irrespective of age and height at diagnosis, catch-up growth was complete in this group of patients, with satisfactory achievement of final height. Only one patient (age at diagnosis 13 years) failed to reach the target height.

Adult↗

PubMed1996

Validity of self reported data on injury prevention behavior: lessons from observational and self reported surveys of safety belt use in the US.

OBJECTIVES: To examine the validity of self reported data on safety belt use and to consider the implications for research on injury prevention behaviors. METHODS: 1992 and 1993 self reported data on safety belt use were obtained from the Behavioral Risk Factor Surveillance System and observational data were obtained from the National Highway Traffic Safety Administrations for 49 states in 1992 and 50 states in 1993. The ratio of self reported to observed belt use was calculated for each state, and linear regression models were used to examine the association between the two methods. RESULTS: There was variation between states, but the overall median ratio of self reported to observed safety belt use was 1.05 in 1992 (interdecile range 0.87-1.36) and 1.02 in 1993 (interdecile range 0.87-1.31). Self reports were substantially higher in southern states and in states with the lowest levels of observed use. Linear regression models indicated a moderately strong association between state estimates using both methods. For every percentage point increase in self reported data in 1993, observed safety belt use increased by 0.95 percentage point. CONCLUSIONS: In the aggregate, self reported estimates were only 2% to 5% higher than observed estimates. This is a substantial improvement from previous studies. This is probably due to the increased prevalence of safety belt use and the declining effects of social desirability on self reported use. In general, the validity of self reported estimates of socially desirable injury prevention behaviors will be higher when the actual prevalence of the behavior is higher, but lower when this is not true.

Accident Prevention↗

PubMed1988

A quantitative method of evaluating the diuretic response to furosemide in rats.

Furosemide effects are usually evaluated by measuring the urinary excretion rate of Na+ (UVNa) in humans. In the present study, however, UVNa showed a nonlinear relationship with urine flow rate after intravenous injection of furosemide in rats. In contrast, when the urinary excretion rate of (Na+ + K+) (UVNa + K) was plotted against the urine flow rate, a linear regression line was observed, with small interindividual variations in normal rats and in rats with uranyl nitrate-induced acute renal failure (ARF). Piretanide, a loop diuretic, also showed a similar relationship, while other types of diuretics revealed different slope values for the relationship. Although the urinary excretion rate of Cl- (UVCl) vs UVNa + K is expected to show a linear relationship in normal rats, the correlation coefficient of the linear regression line was smaller than that of the urine flow rate vs UVNa + K. Further, the slope of UVCl vs UVNa + K was slightly different in ARF rats. Therefore, UVNa + K provides a better quantitative measure of diuretic response to loop diuretics than UVNa or UVCl.

Acute Kidney Injury↗

PubMed1994

Oxygen Fick and modified carbon dioxide Fick cardiac outputs.

OBJECTIVE: To compare cardiac outputs estimated from the classical oxygen Fick and modified CO2 Fick methods with thermodilution cardiac output. The modified CO2 Fick cardiac output was obtained by replacing the oxygen uptake (VO2) in the Fick equation with the CO2 production (VCO2) divided by either an assumed or measured value of the respiratory exchange ratio or with an independently determined constant (Crit Care Med 1991; 19:1270-1277). DESIGN: Criterion standard study. SETTING: The medical and surgical intensive care unit (ICU) in a Veterans Affairs Medical Center. PATIENTS: A total of 17 patients (26 studies) and 11 surgical patients (13 studies), predominantly mechanically ventilated using the intermittent mandatory ventilation mode, were studied over a period of 4.3 hrs. MEASUREMENTS: A respiratory gas exchange monitor was used to measure VO2, VCO2, and respiratory exchange ratio at 3-min intervals. Calculations were performed with arterial and venous oxygen saturations measured with both a laboratory cooximeter and bedside pulse and venous reflectance oximeters. In the oxygen Fick method, cardiac output was calculated from VO2 together with arterial and venous oxygen saturations. In the modified CO2 Fick methods, cardiac output values were calculated from arterial and venous oxygen saturations with VCO2, divided by either: a) an assumed value of the respiratory exchange ratio equal to 0.8 for all patients (method 1); b) the patient's measured value of the respiratory exchange ratio (method 2); or c) a constant, determined from an initial, simultaneous measurement of thermodilution cardiac output, VCO2, and oximetry saturations. Data were examined by linear regression analysis and bias and precision calculations. MAIN RESULTS: Thermodilution cardiac output was more related to cardiac outputs calculated with the 3 modified CO2 Fick methods than to the oxygen Fick cardiac output. Thermodilution cardiac output was closely related to the modified CO2 Fick cardiac output calculated via method 3. For this method, with pulse and venous reflectance oximetry saturations, linear regression yielded an r2 = .85, a standard error of the estimate of 0.88 L/min (n = 111) and a bias and precision of 0.11 and 0.97 L/min, respectively. Thermodilution cardiac output was less closely related to oxygen Fick cardiac output, which, when calculated with pulse and venous reflectance oximetry saturations, yielded an r2 = .50, a standard error of the estimate of 1.47 L/min (n = 128), and a bias and precision of 0.01 and 1.85 L/min, respectively. CONCLUSIONS: We conclude from this study that thermodilution cardiac output is more closely related to cardiac output calculated from modified CO2 Fick methods than to oxygen Fick cardiac output. Since cardiac output calculated with the modified CO2 Fick method 3 obviates the difficulties associated with measuring VO2 accurately and requires neither an assumption of nor measurement of the respiratory exchange ratio, method 3 may prove to be clinically useful for continuous cardiac output monitoring via oximetry in ICU patients.

Adult↗

PubMed2006

Quantification of retinal nerve fiber layer thickness reduction associated with a relative afferent pupillary defect in asymmetric glaucoma.

AIM: The relative afferent pupillary defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. METHODS: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. RESULTS: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (r(s) = -0.729, p<0.0001). Linear regression analysis found an equation that the average RNFL thickness ratio in the more affected eyes relative to that in the less advanced (%) = (0.827-0.169xRAPD (log units))x100 (R(2) = 0.557, p<0.0001). CONCLUSIONS: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

Adolescent↗

PubMed1978

Failure of total calcium corrected for protein, albumin, and pH to correctly assess free calcium status.

The clinical effectiveness of published algorithms in correcting serum total calcium (CaT) for the effects of protein, albumin, and pH was tested. Corrected calcium (CaC) values obtained by 13 of these methods were compared with values of measured free calcium (CaF) in 55 samples from normal controls and 404 samples from patients with various disorders of calcium metabolism. Three criteria were used to compare either CaC or CaT with measured CaF: 1) the correlation coefficient, 2) the average absolute deviation from measured CaF of the values of CaF predicted by the linear regression of CaF on each CaC, and 3) the number of samples in which CaC or CaT gave a different impression of normality than measured CaF. Application of the 13 published algorithms produced varied results, but none produced substantially better agreement between CaC and CaF than was found between CaT and CaF. The application of additional algorithms derived by multiple linear regression using our data base gave slightly better results than any of the published algorithms, but many values of CaC remained which were disparate from the measured value of CaF. Correction of measured total calcium by using other concurrently obtained chemistry values does not seem to adequately predict calcium status as measured by free calcium.

Autoanalysis↗

PubMed2000

[Knowledge about hypertension and blood pressure level].

BACKGROUND: The improvement of efficacy of the hypertension prevention and patient education largely depend on determination of the hypertension risk factors and increase in knowledge about hypertension. The aim of this study was to assess correlation between the environmental factors and knowledge about hypertension and occasionally measured blood pressure values. MATERIALS AND METHODS: The studied group consisted of 485 subjects, who voluntarily participated in the street-based hypertension screening program in Cracow (summer 1997). All subjects were asked to fill out a questionnaire concerning their health behaviours (i.e. stress, smoking and drinking habits) and a test to evaluate their knowledge about hypertension and its risk factors. The blood pressure measurement were taken using semiautomatic device (Digital Blood Pressure UA-702), in the sitting position, after a rest minimum five minutes. The study group consisted of persons with negative history of hypertension (n = 440), and untreated hypertensive patients (n = 45). In order to assess the influence of different factors on blood pressure level, the subjects were divided into two groups according to the presence or absence of a particular risk factor. In the statistical analysis Student's t-test, chi 2 and linear regression analysis with adjustment for possible confuses were used. All values were presented as mean +/- SD. RESULTS: The mean age was 37.1 +/- 17.8 years. Participants were well educated (75.9% had finished college or high school), and there were more women than men in the study group (57.5% vs 42.5%). 24.1% of participants had blood pressure values exceeding 140/90 mmHg. Multiple linear regression demonstrated that age, body mass index and knowledge about hypertension significantly influenced the level of systolic blood pressure; while only body mass index was among the factors determining diastolic blood pressure. CONCLUSIONS: This study confirms the influence of age, male gender, body mass index, alcohol consumption, stress and the snoring on the blood pressure level. The association between the knowledge about hypertension risk factors or hypertension and occasionally measured blood pressure values has been demonstrated.

Adult↗