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PubMed2004

Application of liquid chromatography-mass spectrometry to monitoring plasma cyclophosphamide levels in phase I trial cancer patients.

A specific and efficient liquid chromatography-mass spectrometry (LC-MS) method was established for monitoring patient plasma cyclophosphamide levels in a phase I trial of an oral cyclophosphamide-based combination chemotherapy regimen. An Agilent 1100 Series LC-MSD system (Agilent Technologies, Avondale, PA, USA), with a single quadrupole mass detector using a positive atmospheric pressure chemical ionization (APCI) interface and single ion monitoring at m/z 261, was used. Chromatography was performed using a LUNA C8 5 microm 30 x 4.6 mm stainless steel column (Phenomenex, Torrance, CA, USA) and a mobile phase of aqueous acetonitrile pumped at a flow rate of 0.7 mL/min. High-throughput solid-phase sample extraction was performed using a Gilson ASPEC XL4 system (Gilson Medical, Middleton, WI, USA) controlled by prestored programs. The standard curve for cyclophosphamide was linear over the concentration range 0.026-1.08 microg/mL (r(2) > 0.994). Intra- and interassay accuracy and precision were 97-107 and 3-10%, respectively. The limit of detection was determined to be 0.01 microg/mL. Single ion monitoring at m/z 261 provided a high degree of specificity without interference from the matrix or other chemotherapy drugs. Automated sample processing allowed the analysis of a large number of plasma samples from a clinical trial of repeated daily oral dosing of cyclophosphamide. One hour after dosing, cyclophosphamide was detected in 98 of 106 plasma specimens at concentrations ranging between 0.03 and 4.88 microg/mL. Twenty-four hours after dosing, cyclophosphamide was detected in 72 of 77 plasma specimens at concentrations ranging between 0.06 and 3.13 microg/mL. There were no time-dependent changes in cyclophosphamide concentration during the 43 day period of repeated daily oral dosing. There was no correlation between cyclophosphamide dose and plasma concentration, despite the wide range of doses given in the clinical trial (50-125 mg/m(2)). We conclude that a solid-phase extraction LC-MS technique was validated for determining cyclophosphamide in human plasma. Interoccasion variability in the rate of oral absorption and in the clearance of systemically available drug may have contributed to the wide range of cyclophosphamide concentrations found at 1 and 24 h after tablet ingestion.

Antineoplastic Agents↗

PubMed1983

Abuse of statistical packages: the case of the general linear model.

Since their introduction in the 1960s, packaged computer programs have freed researchers from much drudgery and painstaking computational labor. Before the distribution of these packages, many meaningful projects could not be attempted, simply because the data analysis phase would have been too labor intensive. However, the very ease of use of these packages can lead to their abuse. In particular, performing all possible t tests among numerous groups, calculating many correlations and circling the ones with P values less than 0.05, and performing stepwise regression all can easily lead to spurious statistical conclusions. The danger of these three practices is illustrated with three simple computer runs using random data. In each run statistically significant results were found for the random data.

Animals↗

PubMed2006

Body mass index and the risk of chronic renal failure: the Asian experience.

BACKGROUND: There is a worldwide obesity epidemic, and the number of patients requiring dialysis because of obesity-related renal disease such as diabetes mellitus and hypertension is increasing. Obesity increases the risk of cardiovascular disease and premature death due to chronic kidney disease (CKD) and end-stage renal disease (ESRD). Although the effect of obesity might differ among races, obesity has a significant impact on CKD and ESRD. METHODS: We examined the relationship between obesity (i.e., body mass index [BMI]) and CKD or ESRD using a community based screening registry in Okinawa, Japan. For this purpose, we used a general screening registry (1983, 1993, and 2003), the ESRD patient registry (1971-2000), a hospital-based cardiovascular disease registry (1988-1990), and a hospital-based screening registry (2003). RESULTS: The prevalence of obesity, based on a BMI>or=30 kg/m2, was 3.5% (1983), 4.7% (1993), and 6.2% (2003) in the general adult population. The incidence of ESRD increased when BMI increased, particularly in men. In the hospital-based screening study, the number of components of metabolic syndrome was significantly related with the prevalence of CKD. The relationship was linear when the modified National Cholesterol Education Program criteria were used to define abdominal obesity as a waist circumference of 85 cm or more in men and 90 cm or more in women. CONCLUSION: Although prospective studies are needed, our findings indicate that obesity, including metabolic syndrome, is a potential treatable cause of CKD and ESRD. Rigorous efforts should be made to optimize weight to reduce the risk of CKD and ESRD by a judicious combination of diet, exercise, and psychologic therapies.

Adult↗

PubMed1990

Characterization of the human peripheral lung adenosine receptor.

Because adenosine narrows asthmatic airways, is released during hypoxia and by mast cells, and is antagonized by theophylline, it may play a role in asthma. I characterized the first step in pulmonary responses to adenosine: its adenosine receptor. Plasma membranes, prepared from macroscopically normal human peripheral lung, were incubated with 10 nM 5'-N-ethylcarboxamido[3H]adenosine ([3H]NECA) and various concentrations of competing ligand under experimentally determined optimal conditions: 4 degrees C, pH 7.4, 5 mM MgCl2, 1.8 mg protein/ml, 30-min incubation time. Bound and free ligand were separated by rapid vacuum filtration, and the radioactive counts were analyzed using a weighted, non-linear, least-squares curve-fitting program, LIGAND. Analyzed together, the data from the lungs of 6 patients revealed a single binding site with a dissociation constant (Kd) for NECA of 200 nM +/- 14% and a receptor concentration of 543 fmol/mg protein +/- 13%. Analyzed separately, the individual Kds ranged from 133 to 430 nM and the receptor concentrations from 338 to 811 fmol/mg protein. Adenosine receptor ligands competed with NECA in an A2 rank order of potency: NECA greater than 8-phenyltheophylline greater than 3-isobutyl-1-methylxanthine greater than theophylline greater than N6-L-phenylisopropyladenosine greater than N6-D-phenylisopropyladenosine greater than N6-cyclohexyladenosine. Theophylline bound to the receptor with an inhibition constant (Ki = 70.9 microM +/- 28%) near the therapeutic range (28 to 56 microM). Cromolyn also bound with high affinity (Ki = 5.42 microM +/- 47%). I conclude that human lung adenosine receptors: (1) are single-site receptors, probably of the A2 subtype and (2) bind to both theophylline and cromolyn.

Adenosine↗

PubMed1986

Membrane fluidity and phospholipid composition in relation to sulfur amino acid intake in brush border membranes of rat kidney.

The transport of ions and solutes across biological membranes may relate to changes in the lipid microenvironment of the membrane which could alter the activity or configuration of transport sites. Changes in the sulfur amino acid content of diets fed to young rats results in an increase in Na+-taurine symport in brush border membranes isolated from animals fed a low sulfur amino acid diet and a reduction in symport after a high taurine diet in comparison to uptake by membranes from normally fed animals ("the renal adaptive response"). We explored the possibility that diet-induced changes in brush border membrane symport relate to altered membrane fluidity and phospholipid composition in response to diet. An Arrhenius plot of initial rate (15 s) taurine uptake in breakpoint at 22 degrees C, but no change in relation to dietary alteration. Fluorescence polarization data employing the probe 1-6-diphenyl-1,3,5-hexatriene best fits a two-phase linear model employing a computer model fitting program. Dietary manipulations did not change the breakpoint upper segment slope or lower segment slope after incubating fresh membranes with DPH over the temperature range 4-56 degrees C. No change was evident in membrane phospholipid composition in relation to diet. This study indicates that the changes in initial rate Na+-taurine symport in relation to diet are less likely to be due to changes in the configuration of the transporter from an alteration of the lipid microenvironment of the membrane.

Amino Acids, Sulfur↗

PubMed1985

Ejection fraction and heart rate correlate with diastolic peak filling rate at rest and during exercise.

We investigated the independent variables correlating with the multigated radionuclide peak filling rate (PFR) at rest and during supine bicycle exercise in 20 normal individuals. Independent variables were systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), ejection fraction (LVEF), time to PFR (TPFR), peak ejection rate (PER) and time to PER (TPER). Fifteen subjects completed at least five stages of exercise at 25 watts each. Correlating independent variables were selected by a forward-backward stepwise multiple linear regression (BMDP2R). A partial correlation statistical program was also used to allow control of critical independent variables. The final regression equations were: a) resting state, PFR = -2.5 + 0.03HR + 0.05LVEF + 0.02SBP-0.02DBP, and b) exercise state, PFR = -3.8 + 0.04HR + 0.08LVEF. All independent variables mentioned above correlated with PFR (simple correlations designated as zero partials). However, when LVEF and HR were held constant (second order partials), the correlation of PFR with any of the other independent variables disappeared. In summary, the radionuclide global LV PFR is predominantly correlated to LVEF and HR at rest and during exercise. These correlations should be considered when assessing exercise effects of disease states on PFR.

Adult↗

PubMed2001

Analytical performance of a direct assay for LDL-cholesterol.

We evaluated a direct assay for the determination of LDL-cholesterol (LDL-C) L-Type assay, Wako Pure Chemicals in two laboratories. This assay is applicable to most random access clinical chemistry analyzers, allowing full automation. Between-run coefficient of variation (NCCLS EP5) varied between 1.29% and 3.13% and thus met the National Cholesterol Education Program (NCEP) goal. The assay was considered linear over a physiologically relevant range of LDL-C, 2.22 to 7.04 mmol/l (NCCLS EP6). Method comparison yielded identical results at both evaluation sites for LDL-C when assayed with the direct method. LDL-C results obtained with the homogeneous method under investigation (y) differed significantly from values from density-gradient ultracentrifugation (x) according to Chung (y = 0.87x + 0.43 mmol/l, s(yx) = 0.38 mmol/l, r = 0.91). With the latter method as a reference method, mean bias was 3.16% meeting the NCEP criteria. Diagnostic performance was excellent at a clinically relevant cut-off level of 3.37 mmol/l. Results of the direct method (y) and the commonly used Friedewald formula (x) were highly correlated (s(yx) = 0.22 mmol/l, r = 0.97), but both slope and intercept differed significantly from one and zero respectively (y = 0.90x + 0.37 mmol/l). Bilirubin, hemolysis and ascorbate did not interfere; triglycerides did not cause clinically relevant interference below 11.3 mmol/l. The direct method we investigated is user-friendly and provides an improvement in the determination of LDL-C in routine laboratories.

Apolipoproteins B↗

PubMed2005

Insecure attachment as a predictor of outcome following inpatient trauma treatment for women survivors of childhood abuse.

The role of insecure attachment as a predictor of outcome was investigated in 134 women who reported histories of child abuse and completed an inpatient program for treatment of traumatic stress. Multiple linear regressions were used to predict the change scores on four outcome measures at discharge and 6-month follow-up. Higher levels of feared loss of the attachment figure independent of demographics, symptomatic severity, and trauma exposure consistently predicted poorer outcome at both post-tests. Interventions that focus on internal models of attachment and current attachment relationships may improve outcome in women reporting severe abuse in childhood.

Adult↗

PubMed2000

Ionization characteristics and chemical influences of aspartic acid residue 158 of papain and caricain determined by structure-related kinetic and computational techniques: multiple electrostatic modulators of active-centre chemistry.

The pK(a) of (Asp(158))-CO(2)H of papain (EC 3.4.22.2) was determined as 2.8 by using 4-chloro-7-nitrobenzofurazan (Nbf-Cl) as a reactivity probe targeted on the thiolate anion component of the Cys(25)/His(159) nucleophilic-acid/base motif of the catalytic site. The possibility of using Nbf-Cl for this purpose was established by modelling the papain-Nbf-Cl Meisenheimer intermediate by using QUANTA/CHARMM and performing molecular orbital calculations with MOPAC interfaced with Cerius 2. A pH-dependent stopped-flow kinetic study of the reaction of papain with Nbf-Cl established that the striking rate maximum at pH 3 results from reaction in a minor ionization state comprising (Cys(25))-S(-)/(His(159))-Im(+)H (in which Im represents imidazole) produced by protonic dissociation of (Cys(25))-SH/(His(159))-Im(+)H with pK(a) 3.3 and (Asp(158))-CO(2)H. Although the analogous intermediate in the reaction of caricain (EC 3.4.22.30) with Nbf-Cl has similar geometry, the pH-k profile (k being the second-order rate constant) lacks a rate maximum under acidic conditions. This precludes the experimental determination of the pK(a) value of (Asp(158))-CO(2)H of caricain, which was calculated to be 2.0 by solving the linearized Poisson-Boltzmann equation with the program UHBD ('University of Houston Brownian dynamics'). A value lower than 2.8 had been predicted by consideration of the hydrogen-bonded networks involving Asp(158) and its microenvironments in both enzymes. The difference between these pK(a) values (values not previously detected in reactions of either enzyme) accounts for the lack of the rate maximum in the caricain reaction and for the differences in the electronic absorption spectra of the two S-Nbf-enzymes under acidic conditions. The concept of control of cysteine proteinase activity by multiple electrostatic modulators, including (Asp(158))-CO(2)(-), which modifies traditional mechanistic views, is discussed.

Aspartic Acid↗

PubMed2001

Measuring beyond the microscope field of view using digital images in squamous cell carcinoma of the lip.

OBJECTIVE: To study the impact of using digital images for measuring the size of the tumors, assisting with the prognostic evaluation of carcinomas of the oral mucosa. STUDY DESIGN: The depth of invasion of 12 cases of squamous cell carcinoma of the lower lip was assessed through a microscope and through digital images. All measurements of depth of invasion were assessed in a direction orthogonal to the lip surface. First, assessment of depth of invasion was done at the microscope, using an eyepiece reticule with an engraved scale. Second, depth of invasion was assessed by digital images, using a program module developed to assist pathologists with linear measuring. When the depth of the tumor was larger than the field of view at the proper magnification, several images were taken to include the whole area of invasion. The images were finally mounted in a single image and the depth of invasion measured. RESULTS: The results show positive and negative differences between assessments when assessing depths of < 2 mm. At greater depths (> or = 2 mm), the difference was always negative, showing that for deep invasion, measurements of longer distances were always performed on digital images. CONCLUSION: Measurements with digital images beyond the field of view at proper magnification could sig nificantly alter the diagnostic and prognostic assessment made using the microscope.

Biopsy↗

PubMedDate not supplied

[Atrial fibrillation. New views on an old disease].

Atrial fibrillation (Afib) is clinically the most common arrhythmia. Its main complications are recurrent embolic events and a variable deterioration of functional class. Atrial fibrillation induces changes in cellular ionic channels that self-perpetuate the arrhythmia. The pharmacologic treatment of Afib is directed toward correction of those changes and return to sinus rhythm. It is also intended to maintain adequate heart rates and prevent embolic events through anticoagulation or platelet antiagregation. There are presently several class IC or class III antiarrhythmics available for attempting a return to sinus rhythm. The success rates are irregular, the best achieved with flecainide or propafenone among patients without structural heart disease. Amiodarone is the best choice when there is such a problem. The combination possibilities are huge, so that each case must be individualized. The new class III antiarrhythmics are very effective, but have a relatively high rate of side effects including torsade de pointes. Anticoagulation should be the preferred treatment among the majority of patients, but each case should be individually evaluated. New therapies such as focal or linear catheter ablation techniques, atrial or biatrial programmed stimulation, and atrial cardioverter-defibrillator need longer follow-up and experience to be objectively evaluated, although there are reasons to be optimistic in the future, even if patients need antiarrhythmic support at present. Surgery has high morbi-mortality rates, so it is not the preferred approach.

Algorithms↗

PubMed2003

[Determination of Pb in import ginseng by microwave-digestion graphite-furnace atomic absorption spectrometry].

The determination of lead in import ginseng was studied, where microwave assimilation offers a quick, safe and accurate approach with little pollution compared to conventional methods. In the measurements graphite-furnace atomic absorption spectrometry (GFAAS) was used with the advantages of high sensitivity, high speed and little wastage. The microwave assimilation was programed, the mixed acid was analyzed, the problem of the effect of final assimilating liquid on the inspection results was solved, and the inspection conditions of GFAAS were studied. Based on the many experimental results, the suitable incinerating temperature and atomizing temperature were chosen, and the final graphite-furnace temperature-rising program was determined. This method shows a linear range of 0-100 micrograms.L-1, a determination limit of 2.80 micrograms.L-1, a relative standard deviation of 0.91% and a recovery of 98.13%. The precision and accuracy are satisfying.

Drug Contamination↗

PubMed2004

Influence of the partial denture on the articulation of dental and postalveolar sounds.

Dental prosthesis is a foreign body in oral cavity and thus necessarily interferes with speech articulation. The purpose of this study was to examine influence of partial denture on speech quality and to show eventual differences in pronunciation of dental sounds c[ts], z [z], s [s] and postalveolar sounds c [t], z [3] and s [integral of]. We have examined differences in pronunciation between subjects with removable partial dentures, the same group without partial dentures and a control group. The study was performed on 30 subjects with removable partial dentures and 30 subjects with complete dental arch. All subjects were recorded while reading six Croatian words containing the examined sounds. Recordings were analyzed with Multispeech Program (Kay Elemetrics Inc.). Acoustic analysis--LPC (linear prediction coding) provided formant peaks (Hz) for each examined sound, its intensity (dB) and formant bandwidths (Hz). Results showed that subjects with partial dentures had 50% less distorted variables and that prostheses did not completely restore articulation of postalveolar sounds. Groups with and without prostheses had lower formant peaks intensities and wider formant bandwidths in comparison to the control group. Partial dentures have not significantly interfered with resonance frequency. At the same time, pronunciation of the examined sounds was significantly improved. However, precision of the articulation movements has deteriorated.

Denture, Partial↗

PubMed1991

A comparative study of methods of photoreceptor morphometry.

A comparative study was performed to compare methods of quantitative evaluation of damage to photoreceptor cells in rat eyes exposed to light. Using a manual count of individual photoreceptor nuclei as the standard, the following measurements were compared: (1) outer nuclear layer column count, (2) area, (3) thickness, and (4) the number of nuclei of the outer nuclear layer of the retina using a newly developed computer program that counts a digitized image. Linear-regression analysis of the data showed that the computer method was the most accurate with a Pearson correlation coefficient of 0.9911. The other methods tested also correlated well with the manual count, with coefficients ranging from 0.9367-0.9532. All these methods were reasonably accurate measurements of photoreceptor layer integrity, with the computer count most closely approximating the values obtained by a manual count. However, the outer nuclear layer thickness measurement appeared to be the fastest and most convenient method to evaluate photoreceptor cell damage quantitatively. Computer counting could be reserved for situations in which a high degree of accuracy is required.

Animals↗

PubMed1986

Cumulative incidence rates for Hodgkin's disease and other hematologic malignancies, with special reference to age-related carcinogenesis.

The cumulative incidence rate throughout the life span was analyzed for 4,865 Hodgkin's disease cases, in comparison with 16,015 malignant lymphomas (ML), 1,694 acute lymphocytic leukemias (ALL), 3,967 acute myeloid leukemias (AML), 2,109 chronic myeloid leukemias (CML), and 4,752 chronic lymphoid leukemias (CLL) in US white reported in the SEER program during 1973-1981. A log-linear increase was observed in ML, AML, CML, and CLL throughout the life-span, but only in childhood in ALL. Hodgkin's disease showed a steep increase until age 20-24, and then the increase became much more gradual. The cumulative incidence rates for males and females were parallel for ML and leukemias, but diverged for Hodgkin's disease (the rate for females had a lower slope than that for males after age 20-24). This difference was mainly caused by a lower frequency in females of mixed cellularity and lymphocyte predominance subtypes. The incidence curve of Hodgkin's disease was consistent with the two-stage model of carcinogenesis; it is likely that the proliferation of progenitor cells peaks at a young age and that the death rate of so-called intermediate cells is a primary influence during the subclinical stage. The cytogenesis of Hodgkin's disease and the histologic variation with special reference to the T-zone histiocytes suggest that a strong host defense mechanism against neoplastic change is involved, rather than different etiologic influences.

Adolescent↗

PubMed1993

[Determination of height in life using multiple regression of skull parameters].

The Authors have evaluated the possible correlations between cranial diameters and height in a population of 358 young males aged between 17 to 27 years old. The maximum anterior-posterior and lateral cranial diameters were measured along with stature. Then, the data was correlated using the SAS Program (Stepwise method) to obtain a multiple linear regression between height (dependent variable) and the cranial diameters (independent variable). Secondly, the Authors also studied the probable correlation between height and cranial diameters obtained without including the thickness of the soft tissues. In conclusion, they proposed a mathematical formula, applicable in forensic investigation, regarding the determination of the actual living stature of subjects for whom skills are the only skeletal remains available for identification procedures.

Adolescent↗

PubMed1993

Analysis of enzyme-linked immunosorbent assay data for antigen quantitation using Lotus 1-2-3 software on a personal computer.

Absorbance data obtained in double-antibody sandwich enzyme-linked immunosorbent assay tests for quantitation of antigens are analyzed by a personal computer using the Lotus 1-2-3 software package. The sigmoid standard curve is processed by an iterative weighted regression analysis in the logit-log domain to obtain a linear dose-response relationship. A macro program is developed for quick calculation with easy operation, which is suited for routine laboratory tests in biomedical fields.

Antigens↗

PubMed1985

Economic specification of cost estimates in dental programs.

This paper compares two approaches to the estimation of costs in dental care programs: a conventional approach and an approach based on theoretical expectations. The conventional approach typically uses a linear extrapolation of an average figure - e.g., cost per visit - over various program sizes and thus predicts constant costs. Constant costs are, however, theoretically implausible, and it should be anticipated that their use in program planning or analysis would generate biased estimates. This hypothesis is examined using annual costs and visits from a group of uniform clinics over a five-year period. Results show that costs calculated by the conventional method are underestimated at low volumes and increasingly over-estimated at higher volumes. The findings, which illustrate how in-efficiency can inadvertently be incorporated into program design, have implications for cost-effectiveness of dental care delivery in the public sector.

Child↗