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PubMed2000

[Simultaneous determination of tryptophan and tyrosine by second order derivative fluorimetry].

A new method of second order derivative fluorimetry for the simultaneous determination of tryptophan and tyrosine is described. The measurement of emission spectra is carried out with excitation at 221 nm in a KH2PO4-NaOH buffer solution (pH = 7.4). The second-derivative peak is at 318 nm and 283 nm for tryptophan and tyrosine respectively. The two amino acids can be determined directly from corresponding second order derivative signals. Linear regression equation of the calibration graph is c = 0.000 7H-0.004, with a correlation coefficient of linear regression of 0.9964 for tryptophan and c = 0.001 2H-0.0040, with a correlation coefficient of linear regressin of 0.9971 for tyrosine. The linear ranges of determination of tryptophan and tyrosine are from 0.004 to 0.200 microgram.mL-1 and from 0.002 to 0.025 microgram.mL-1, respectively. Effects of pH, temperature and foreign ions on the determination of tryptophan and tyrosine have been examined. Recovery is from 92.0% to 104% for tryptophan and 98.7% to 102.0% for tyrosine, and relative standard deviation of 3.5% and 2.8%, respectively.

Fluorometry↗
PubMed2003

Rate of optic disc cup progression in treated primary open-angle glaucoma.

PURPOSE: To quantitatively evaluate the rate of cup-to-disc ratio progression in treated patients with primary open-angle glaucoma and to identify clinical factors associated with cup progression. PATIENTS AND METHODS: Fifty one eyes of 51 treated primary open-angle glaucoma patients with a minimum of 9-year longitudinal series of stereoscopic optic disc photographs were studied. Eyes with any other ocular disease except for mild cataract were excluded. Each set of stereoscopic photographs was digitized and viewed stereoscopically on a computer screen using a hand-held stereoscope. Computer-aided planimetry was performed on each set of photographs with examiner-defined cup and disc margins using custom-made software. The software computed linear cup-to-disc ratios as well as peripapillary atrophy area. Both inter-observer and intra-observer reliabilities were evaluated in a masked, random fashion using intra-class correlation. Changes in linear cup-to-disc ratios and peripapillary atrophy were estimated using linear regression over time. All available clinical factors were evaluated for association with the rate of cup progression using a multiple regression model. RESULTS: All patients studied were Caucasian; 31(61%) were females. The mean age at the beginning of the study was 61.6 +/- 7.8 years (range 46-81). The mean follow-up period was 14.3 +/- 3.5 years (median 14.0, range 9.6-22.3). A total of 173 sets of stereo disc photographs were analyzed (3.4 +/- 1.3 per patient). The initial and final linear cup-to-disc ratios were 0.64 +/- 0.15 and 0.73 +/- 0.14 respectively. The inter-rater and intra-rater intraclass correlations were 0.76 (95% CI 0.61-0.87) and 0.97 (95% CI 0.93-0.98) respectively. Using linear regression the rate of linear cup-to-disc ratio change was 0.0068 +/- 0.0062 per year (range -0.0025- 0.0269). Three eyes had an increase in the peripapillary atrophy area. The higher yearly average intraocular pressure was significantly associated with faster rate of linear cup-to-disc ratios progression (P = 0.03). CONCLUSIONS: In treated patients with primary open-angle glaucoma, the rate of progressive optic disc cupping was slow (LCDR progression of 0.0068 per year). The higher yearly average intraocular pressure was significantly associated with a faster rate of cup progression.

Aged↗
PubMed1995

Measurement of facial growth in the human fetus.

BACKGROUND: The fetal face is clearly seen by ultrasonography: we considered measurement of certain orbitofacial parameters of interest in the human fetus in order to establish norms for facial development. METHODS: We included 108 "normal" fetuses ranging in age from 16.5 to 41 weeks of amenorrhea. The orbitofacial parameters studied were outer canthal distance, inner canthal distance, oropalpebral distance right side and left side, and palpebral fissure length side and left side. The ocular parameters studied were corneal horizontal diameter and axial length. The traditional anthropometric parameters of the fetus were determined by pathological examination: age, weight head circumference and height. A statistical study analyzed the different correlations and established linear regression equations for orbitofacial parameters as a function of age. Polynomial regression models were tested to the third degree as a function of age and the head circumference/II ratio. RESULTS: Results are given in six different age groups. We find excellent correlation between the different parameters. Statistically valid linear regression equations were established for orbitofacial parameters. Polynomial regression equations were compared to linear equations their correlation coefficient and standard error, but showed no greater validity. Skull growth is more rapid than facial growth, which itself is more rapid vertically than horizontally. CONCLUSION: This study establishes norms for the different orbitofacial parameters, in particular the oropalpebral distance, for which we found no bibliographic references. The general interest of these measures lies in the description of malformation syndromes.

Anthropometry↗
PubMed1999

A comparison of proxy measures of abdominal obesity in Chinese, European and South Asian adults.

AIMS: To assess whether four proxy measures of abdominal obesity (waist circumference; waist-to-hip ratio (WHR); waist-to-height ratio and C index, a measure of body shape) were uniformly associated with features of the metabolic syndrome (triglycerides, high density lipoprotein (HDL) cholesterol, 2-h glucose) in three ethnic groups. METHODS: Anthropometric and biochemical data were collected in 629 Europeans (320 men, 309 women), 380 Chinese (183 men, 197 women) and 597 South Asians (275 men, 322 women) aged 25-64 years in Newcastle upon Tyne, UK. Linear regression models were used to determine whether relationships differed between ethnic groups. RESULTS: Linear regression analysis showed that most proxy measures of abdominal obesity were associated with features of the metabolic syndrome. There were significant interactions between WHR and ethnicity and C index and ethnicity in the relationship with log triglycerides when comparing European and Chinese women. Interactions existed between all proxy measures and ethnicity in the relationship with log triglycerides and HDL cholesterol when comparing European and South Asian women. In men, interactions between ethnicity and waist circumference, WHR and C index when comparing Europeans and South Asians, and between ethnicity and WHR and C index when comparing South Asian and Chinese for log 2-h glucose were significant (P < 0.001). All interactions remained significant when differences in smoking, alcohol and physical activity were taken into account. CONCLUSIONS: Not all the proxy measures of abdominal obesity were consistently related to features of the metabolic syndrome across the ethnic groups studied. However, waist circumference and waist to height ratio were the most consistent and WHR the least when comparing across the ethnic groups.

Abdomen↗
PubMed2004

Spectrophotometric determination of dapsone in pharmaceutical products using sodium 1,2-naphthoquinone-4-sulfonic as the chromogenic reagent.

Spectrophotometric determination of dapsone is described. The dapsone reacts with sodium 1,2-naphthoquinone-4-sulfonic in pH 6.98 buffer solution to form a salmon pink compound, and its maximum absorption wavelength is at 525 nm, epsilon525=3.68 x 10(4) l mol(-1) cm(-1). The absorbance of dapsone from 0.40 to 10 microg ml(-1) obeys Beer's law. The linear regression equation of the calibration graph is C=0.2334 A + 0.01288, with a linear regression correlation coefficient of 0.9998, the detection limit is 0.24 microg ml(-1), and recovery is from 99.2 to 102.4%. Effects of pH, surfactant, organic solvents, foreign ions, and standing time on the determination of dapsone have been examined. This method is simple and can be used for the determination of dapsone in injection solution of dapsone. The results obtained by this method agreed with those by the official method (dead-stop titration method [The Chinese Pharmacopoeia, Pharmacopoeia Commission, Ministry of Health, vol. 2, fifth ed., PRC Chemical Industry Press, Beijing, 2000, p.720]).

Antimalarials↗
PubMed2004

Spectrophotometric determination of ampicillin sodium in pharmaceutical products using sodium 1,2-naphthoquinone-4-sulfonic as the chromogentic reagent.

Spectrophotometric determination of ampicillin sodium is described. The ampicillin sodium reacts with sodium 1,2-naphthoquinone-4-sulfonic in pH 9.00 buffer solution to form a salmon pink compound, and its maximum absorption wavelength is at 463 nm, epsilon463 = 1.14 x 10(4). The absorbance of ampicillin sodium from 2.0-80 microg ml(-1) obeys Beer's law. The linear regression equation of the calibration graph is C = 40.24A - 2.603, with a linear regression correlation coefficient is 0.9997, the detection limit is 1.5 microg ml(-1), recovery is from 97.23 to 104.5%. Effects of pH, surfactant, organic solvents, and foreign ions on the determination of ampicillin sodium have been examined. This method is rapid and simple, and can be used for the determination of ampicillin sodium in the injection solution of ampicillin sodium. The results obtained by this method agreed with those by the official method (HPLC).

Absorption↗
PubMed2003

Spectrophotometric determination of procaine hydrochloride in pharmaceutical products using 1,2-naphthoquinone-4-sulfonic acid as the chromogenic reagent.

Spectrophotometric determination of procaine hydrochloride is described. The procaine hydrochloride reacts with 1,2-naphthoquinone-4-sulfonic acid in pH 3.60 buffer solution to form a salmon pink compound, and its maximum absorption wavelength is at 484 nm, epsilon(484)=5.22 x 10(3).The absorbance for procaine hydrochloride from 0.30 to 100 microg ml(-1) obeys Beer's law. The linear regression equation of the calibration graph is C=19.23A-0.03, with a linear regression correlative coefficient is 0.9996, the detection limit is 0.28 microg ml(-1); recovery is from 98.0 to 105.2%. Effects of pH, surfactant, organic solvent, foreign ions, and standing time on the determination of procaine hydrochloride have been examined. This method is rapid and simple, and can be used for the determination of procaine hydrochloride in injection solution of procaine hydrochloride. The results obtained by this method agreed with those by the official method (dead-stop titration).

Hydrogen-Ion Concentration↗
PubMed2002

Growth performance of broilers using a phase-feeding approach with diets switched every other day from forty-two to sixty-three days of age.

Phase-feeding (PF; Treatment 2) was tested relative to an NRC regimen (Treatment 1) to evaluate the impact of PF on broilers during the finisher period (42 to 63 d). Two modified PF treatments were also tested during this experiment: Treatment 3 involved lowering the amino acid requirements predicted with PF linear regression equations by 10% (PF10), Treatment 4 involved increasing the slope of the linear regression equations by 15% (PF15). Broilers fed Treatment 1 consumed a single diet throughout the experiment, whereas PF treatments were fed in a series of 11 diets in which feed was switched every other day, resulting in steadily decreasing lysine, SAA, and threonine levels. On Day 63, weight gain, feed intake, feed efficiency, and crude protein intake did not differ (P > 0.05) among birds fed PF treatments and Treatment 1. Digestible lysine and threonine intakes were increased (P < 0.05) for Treatment 1 relative to the PF treatments, and digestible SAA intake for the NRC treatment was increased (P < 0.05) relative to the PF10 and PF15 treatments. Compared to Treatment 1, no differences (P > 0.05) in percentage breast, wing, leg, or abdominal fat were observed when birds were fed PF, PF10, or PF15 diets. These results indicate that PF supports maximum growth performance during an extended finisher period, even when lysine, SAA, and threonine levels are reduced every other day. Economic analysis indicated that PF regimens may lead to savings ($ per kg weight gain or breast meat).

Amino Acids↗
PubMed1994

Relationship between Cr and breathing pattern in mechanically ventilated patients.

In mechanically ventilated patients the natural gas-conditioning process of the upper airways is bypassed by the use of an endotracheal tube or a tracheostomy. We hypothesized that under these conditions the breathing pattern may greatly influence the convective respiratory heat loss (Cr). Cr values were computed from minute ventilation (VE) and inspiratory and expiratory gas temperatures, which were measured in six patients under mechanical ventilation for the management of cranial trauma. In each patient the effects of 11-20 different breathing patterns were investigated. Relationships between Cr and VE and between combined tidal volume and respiratory frequency were obtained by simple and multiple linear regression methods, respectively. Comparison of the standard errors of estimate indicated that multiple linear regression gives the best fit. Thus, Cr was highly dependent on the breathing pattern and was not related only to VE. For the same VE value, Cr was higher when VE was achieved with high tidal volume and low respiratory frequency. These data are consistent with previous studies in which thermal exchanges through the upper airways were taxed by hyperventilation of frigid air.

Adult↗
PubMed1989

The distribution of bronchial responsiveness to histamine in symptomatic and in asymptomatic subjects. A population-based analysis of various indices of responsiveness.

The distribution of bronchial responsiveness (BR) and the place of symptomatic subjects in this distribution was investigated in a random population sample of 339 subjects who participated in the 1984 survey of the Vlagtwedde/Vlaardingen Study. BR was assessed by a histamine provocation test. The following indices of BR were used: (1) a histamine threshold both at 10 and at 20% decreases in FEV1 (PC10 and PC20); (2) the concentration causing a 10 or a 20% decrease estimated by linear interpolation (IPC10 and IPC20), and by linear regression of all data points (PD10 and PD20); (3) the slope of the linear regression line through all data points (SAP) and the slope of the line through the origin and the last data point (SOL). Disease was defined as the self-reported presence of respiratory symptoms from a respiratory symptom questionnaire. Bronchial challenge was considered as a test to predict symptom prevalence. Receiver-operator characteristic curves were applied to define optimal cutoff points for each of the indices used to define a positive and a negative test. For each index, sensitivity, specificity, predictive value of a positive and negative test, and efficiency rate of the test were calculated. The overall distribution of BR in this population appeared to be log normal for the different continuous indices. Subjects with symptoms were on the more responsive tail of the distribution. After adjusting for age, sex, smoking habit, and level of pulmonary function, the mean log-transformed values of PD10, PD20, SAP, and SOL for the various symptom groups differed significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2002

[Determination of procaine hydrochloride by fluorimetry].

Use of fluorescence spectrophotometry for the determination of procaine hydrochloride in injection solution of procaine hydrochloride in suggested based on fluorescence property of 4-aminobenzoate which is a hydrolysis product of the procaine hydrochloride in pH 12, with exciatation wavelength and emission wavelength at 268 and 340 nm, respectively. Under this condition, a linear relationship is obtained between procaine hydrochloride and the relative fluorescence intensity. The linear regression equation of the calibration graph is c = 0.022I-0.081, with a linear regression correlative coefficient of 0.9996 and relative standard deviation (RSD) of 3.4%. Influences of pH, foreign ions, kanamycin, gentamycin, benylpencillin, streptomycin and standing for time on the determination of procaine hydrochloride have been examined. The reasons that the relative fluorescence intensity of procaine hydrochloride increases with a rise in pH and with standing for time are discussed. The detection limit of this method is 49 ng.mL-1. The results obtained by the method agreed with those by the official method. The method is simple, and available to be used in the determination of procaine hydrochloride in injection solution.

4-Aminobenzoic Acid↗
PubMed2004

Time delay-adjusted survival benefit of angioplasty over thrombolysis in acute myocardial infarction: influence of time from symptom onset.

BACKGROUND: The time-to-treatment is a critical determinant of outcome after acute myocardial infarction. We investigated the relationship between the primary angioplasty (PCI)-related time delay and the benefit of PCI over thrombolytic therapy (TT), considering the time elapsing from symptom onset in 21 randomized trials comparing PCI to TT. METHODS: PCI-related time delay was calculated as the median of the "door-to-balloon" time minus the median of the "door-to-needle" time. The survival benefit was defined as the difference between 30-day mortality after TT and after PCI. The relationships between time delay and benefit were assessed by linear regression. RESULTS: PCI-related time delay ranged from 7 to 104 min. Linear regression showed that at a PCI-related delay of 75 min, PCI and TT yielded equivalent reductions in mortality (p = 0.03). When the trials with the longest and shortest delays were excluded, the benefit of PCI over TT was nullified after a delay of 62 min, and every additional 10-min delay produced a 1.1% increase in mortality (p = 0.01). When trials with a symptom duration < 6 hours (median 130 min) were considered, PCI-related delay still correlated with an absolute risk reduction in 30-day mortality with a time to equipoise of 57 min (p = 0.03). Lack of correlation (p = 0.85) was observed in trials enrolling patients within 12 hours of symptom onset (median 185 min). CONCLUSIONS: Our analysis suggests that PCI-related delay substantially modifies the benefit of PCI over TT, particularly in case of patients presenting early following symptom onset.

Angioplasty↗
PubMed1991

[Quantitative study of myocardial pathological lesions in rheumatic mitral valve disease: correlations with changes in cardiac function after valve replacement].

Pathological lesions of left ventricular myocardium from 21 patients with predominant mitral stenosis (MS) and from 16 patients with predominant mitral regurgitation (MI) were studied quantitatively by means of image analysis system and light microscopic examination. Their correlations with changes of cardiac function after mitral valve replacement were also studied. The results showed that the percentage of the area of interstitial fibrosis (F%), the shortest diameter of myocardial fiber (SDMF) and endocardial thickness (ET) increased, and the inner diameter-out diameter ratio of intramyocardial arteries (Di/Do) decreased in 37 patients in various degrees. F%, Di/Do, SDMF and ET correlated with delta EF, delta FS, delta ESVI, postoperative dosage of dopamine, and duration of assisted respiration analysed respectively by linear regression. Multiple myocardial pathological lesions correlated strongly with delta EF analysed by multiple linear regression with multiple correlation coefficient of 0.803 in MS group (P less than 0.01) and 0.763 in MI group (P less than 0.05). These data suggest that multiple evaluation of myocardial pathological lesions plays an important role in predicting prognosis of mitral valve replacement. After operation mean delta EF and delta FS decreased, dosage of dopamine and duration of assisted respiration increased when the patient had two or more following criteria: 1. F% greater than 31%, 2. Di/Do less than 0.400, 3. SDMF greater than 16 microns, 4. ET greater than 326 microns.

Adolescent↗
PubMed1995

[Incidence of insulin-dependent diabetes mellitus in Switzerland (1972-1993) in 19-year-old men].

There is current debate whether prevalence of insulin-dependent diabetes mellitus is increasing in western countries. In Switzerland every male at age 19 years is legally obligated to appear before the Military Conscript Board, where health status is determined by physicians. We analyzed prevalence data concerning the diagnosis of diabetes mellitus in four full surveys (1972, 1982, 1987, 1993). The study included data from 162,607 Swiss males at age 19 years. Case numbers of birth cohorts and prevalence rates per 1000 are the following: [table: see text] Although the number of years surveyed is limited, trend analysis showed no evidence of an increase in the diabetes rates (total chi 2 = 4.953, DF = 3, 0.1 < p 0.2; chi 2 due to linear regression = 3.013, DF = 1, 0.05 < p < 0.1; chi 2 due to departure from linear regression = 1.940, DF = 2, 0.3 < p < 0.5). Overall cumulative incidence of diabetes mellitus was 1.30/1000 conscripts (95% confidence interval: 1.13-1.48/1000). We conclude that, in contrast to reports from other European countries, the cumulative incidence of insulin dependent diabetes mellitus has not increased among cohorts of Swiss males at age 19 years.

Adult↗
PubMed2005

Artificial neural networks in prediction of bone density among post-menopausal women.

Artificial neural networks (ANN) are promising tools in learning complex interplay of factors on a particular outcome. We performed this study to compare the predictive power of ANN and conventional methods in prediction of bone mineral density (BMD) in Iranian post-menopausal women. A database of 10 input variables from 2158 participants was randomly divided into training (1400), validation (150) and test (608) groups. Multivariate linear regression and ANN models were developed and validated on the training, and validation sets and outcomes (femoral neck and lumbar T-scores) were predicted and compared on the test group using different numbers of input variables. Results were evaluated by comparing the mean square of differences between predicted and reference values (non-central chi-square test) and by measuring area under the receiver operating characteristic curve (AUROC) around cut-off value of -2.5 for T-scores. For models with less than 3 input variables in femoral neck and 4 variables in spinal column, performance of regression and ANN models was almost the same. As more variables imported into models, ANN outperformed linear regression models. AUROC varied in 2 to 10 variable models as follows: for ANN in spine, from 0.709 to 0.774; linear models in spine, from 0.709 to 0.744; ANN in femoral neck, from 0.801 to 0.867; linear models in femoral neck, from 0.799 to 0.834. The ANN model performed better than five established patient selection tools in the test group. Superior performance of neural networks than linear models demonstrate their advantage especially in mass screening applications, when even a slight enhancement in performance results in significant decrease in number of misclassifications.

Aged↗
PubMed2006

Spatial analysis of Aedes albopictus (Diptera: Culicidae) oviposition in suburban neighborhoods of a Piedmont community in North Carolina.

Temporal and spatial distribution of egg-laying by Aedes albopictus (Skuse) (Diptera: Culicidae) was investigated in suburban neighborhoods in Raleigh, NC, by using oviposition traps (ovitraps) at fixed sampling stations during the 2002 and 2003 mosquito seasons. Variations in the phenology of oviposition between the two mosquito seasons resulted from differences in the patterns and amounts of rainfall early in the season. Aerial images of each study neighborhood were digitized, and the proportions of specific types of land cover within buffer zones encompassing ovitraps were estimated. Retrospective analyses showed that in some neighborhoods, oviposition intensity was significantly associated with specific types of land cover. However, in general, it seemed that gravid Ae. albopictus searched throughout the landscape for water-filled containers in which to lay eggs. Peridomestic surveys were carried out concurrently with ovitrap collections to estimate production of Ae. albopictus pupae in discarded water-filled containers and the abundance of females in vegetation that made up the resting habitat. Results of linear regression analyses indicated that the mean standing crop of pupae (total and per container) per residence was not a significant predictor of mean egg densities in ovitraps. However, the mean standing crop of adult females was a significant but weak predictor variable, because the magnitude and sign of regression coefficients varied between neighborhoods. Linear spatial regression analyses revealed that oviposition intensity was not spatially dependent on pupal standing crop or the numbers of pupae-positive containers distributed peridomestically. However, a weak spatial dependence on the standing crop of adult females was found in some neighborhoods. Based on spherical variogram models, kriging was carried out to predict the spatial patterns of oviposition in suburban neighborhoods. Focal areas of high and low oviposition intensity were evident in most neighborhoods; however, the spatial patterns of oviposition changed between mosquito seasons. Kriging predictions were evaluated, using cross-validation, by systematically removing each data point from our data set and predicting the removed point by using the remaining points. The root mean square (standardized) error values of best fitting variogram models approximated 1, and plots of standardized PRESS residuals showed no distinct pattern for most neighborhoods, indicating that predictions of the spatial distribution of oviposition intensity were valid. Spherical variogram models are a satisfactory method for describing the spatial distribution of Ae. albopictus oviposition, and kriging can be a useful technique for predicting oviposition intensity at locations that have not been sampled.

Aedes↗
PubMed1981

Flow-volume curves in healthy non-smokers and in smokers.

Maximum expiratory flow-volume curves were recorded in lung healthy non-smokers and in smokers. Multiple linear regression analysis was performed with regard to sex, age, height and weight. The regressions for maximum expiratory flow at 50% and 25% of vital capacity (MEF50 and MEF25, respectively) on age were significantly different for non-smokers and smokers, in males as well as females, but the large scatter around the regression line resulted in more than 50% of presently studied smokers to fall within 1 SD of the reference values for non-smokers. A skew distribution of MEF25 around the mean was observed at ages above 60 years and so set an upper limit for the linear regression. Above 60 years no linear age dependence was found for MEF25. There was a minor reduction (2%) in the residual standard deviation of the peak expiratory flow (PEF), MEF50 and MEF25 regressions when height was added as an independent variable besides age, while the addition of weight did not reduce the scatter. We conclude that the inter-individual variability in MEF50 and MEF25 is relatively large even when sex and age are accounted for and that there is no further benefit in including height or weight in the regression equations. The discriminating ability of the MEF50 and MEF25 variables is small, indicated by considerable overlapping between non-smokers and smokers.

Adolescent↗
PubMed2003

Rank regression in stability analysis.

Stability data are often collected to determine the shelf life of certain characteristics of a pharmaceutical product, for example, a drug's potency over time. Statistical approaches such as the linear regression models are considered as appropriate to analyze the stability data. However, most of these regression models in both theory and practice rely heavily on their underlying parametric assumptions, such as normality of the continuous characteristics or their transformations. In this article, we propose and study some rank-based regression procedures for the stability data when the linear regression models are semiparametric with unspecified error structure. Numerical studies including Monte Carlo simulations and practical example are demonstrated with the proposed procedures as well.

Drug Stability↗