Highly sensitive quantitation of methamphetamine by time-resolved fluoroimmunoassay using a new europium chelate as a label.
A simple and highly sensitive time-resolved fluoroimmunoassay of methamphetamine (MA) using a new fluorescent europium chelate (BHHCT-Eu3+) as a label is described. Two variations of competitive immunoassay were attempted. In the first (one-step) assay, microtiter plates coated with anti-MA were used, and the new label was bound to a conjugate of bovine serum albumin and N-(4-aminobutyl)-MA (MA-BSA). In the second (two-step) assay, instead of the labeled MA-BSA, biotinylated MA-BSA and BHHCT-Eu3+-labeled streptavidin-BSA were used. The lowest measurable concentrations of MA for the one-step and the two-step methods were 1 ng/mL (25 pg/assay) and 1 pg/mL (25 fg/assay), respectively. These were 10 to 1000 times superior to the detection limits of MA in any other immunoassay. Intra-assay coefficient of variation was approximately 2-8% at eight different concentrations (n = 4). Analysis of 34 urine samples with the new method and conventional gas chromatography showed a good correlation (r = 0.954). The high detectability of the present assay also enabled segmental hair analysis with a few centimeters of a hair. (+info
Urinary lithium: distribution shape, reference values, and evaluation of exposure by inductively coupled plasma argon-emission spectrometry.
Inductively coupled plasma argon-emission spectrometry (ICPAES) was used to evaluate the lithium content of undiluted urine samples. The method can be performed with 1 mL of urine in a single tube using a routine ICPAES analysis for rapid and convenient assessment of lithium exposure in humans. Urine samples obtained from male workers (n = 86) who had not been exposed to lithium were used for the determination of this element by ICPAES. The obtained concentrations were corrected using a specific gravity of 1.024. The particular frequency distribution resulted in a log-normal distribution diagram for anatomical spread. Geometric mean value for urinary lithium in the nonexposed male workers was 23.5 microg/L, and the confidence interval from a log-normal distribution was 11.0 to 50.5 microg/L. Taking into consideration a short biological half-life and the massive urine excretion of lithium, urinary lithium was considered to be a useful index for monitoring of exposure. Calibration curves obtained for lithium standards had good sensitivity and linearity. Good reproducibility was assessed by lithium addition to urine samples. It was concluded that the obtained lithium reference values would be useful for the early diagnosis of lithium intoxication or in the assessment of the degree of exposure to lithium in subjects at risk. (+info
Transient and permanent deficits in motion perception after lesions of cortical areas MT and MST in the macaque monkey.
We examined the nature and the selectivity of the motion deficits produced by lesions of extrastriate areas MT and MST. Lesions were made by injecting ibotenic acid into the representation of the left visual field in two macaque monkeys. The monkeys discriminated two stimuli that differed either in stimulus direction or orientation. Direction and orientation discrimination were assessed by measuring thresholds with gratings and random-dots placed in the intact or lesioned visual fields. At the start of behavioral testing, we found pronounced, motion-specific deficits in thresholds for all types of moving stimuli, including pronounced elevations in contrast thresholds and in signal-to-noise thresholds measured with moving gratings, as well as deficits in direction range thresholds and motion coherence measured with random-dot stimuli. In addition, the accuracy of direction discrimination was reduced at smaller spatial displacements (i.e. step sizes), suggesting an increase in spatial scale of the residual directional mechanism. Subsequent improvements in thresholds were seen with all motion stimuli, as behavioral training progressed, and these improvements occurred only with extensive behavioral testing in the lesioned visual field. These improvements were particularly pronounced for stimuli not masked by noise. On the other hand, deficits in the ability to extract motion from noisy stimuli and in the accuracy of direction discrimination persisted despite extensive behavioral training. These results demonstrate the importance of areas MT and MST for the perception of motion direction, particularly in the presence of noise. In addition, they provide evidence for the importance of behavioral training for functional recovery after cortical lesions. The data also strongly support the idea of functional specialization of areas MT and MST for motion processing. (+info
Comparative efficacy of positron emission tomography with FDG and computed tomographic scanning in preoperative staging of non-small cell lung cancer.
OBJECTIVE: To determine the sensitivity, specificity, and accuracy of positron emission tomography with 2-fluorine-18-fluorodeoxyglucose (PET-FDG) in the preoperative staging (N and M staging) of patients with lung cancer. The authors wanted to compare the efficacy of PET scanning with currently used computed tomography (CT) scanning. MATERIALS AND METHODS: Results of whole-body PET-FDG imaging and CT scans were compared with histologic findings for the presence or absence of lymph node disease or metastatic sites. Sampling of mediastinal lymph nodes was performed using mediastinoscopy or thoracotomy. RESULTS: PET-FDG imaging was significantly more sensitive, specific, and accurate for detecting N disease than CT. PET changed N staging in 35% and M staging in 11% of patients. CT scans helped in accurate anatomic localization of 6/57 PET lymph node abnormalities. CONCLUSION: PET-FDG is a reliable method for preoperative staging of patients with lung cancer and would help to optimize management of these patients. Accurate lymph node staging of lung cancer may be ideally performed by simultaneous review of PET and CT scans. (+info
Permanent work incapacity, mortality and survival without work incapacity among occupations and social classes: a cohort study of ageing men in Geneva.
BACKGROUND: The objective of this retrospective cohort study was to investigate the burden of disability and death in men, from middle age to age of retirement, among occupational groups and classes in Geneva. METHODS: Men were included if they resided in the Canton of Geneva, were 45 years of age in 1970-1972, and were not receiving a disability pension at the start of the follow-up. The cohort of 5137 men was followed up for 20 years and linked to national registers of disability pension allowance and of causes of death. RESULTS: There was a steep upward trend in incidence of permanent work incapacity with lower social class for all causes as well as for the seven causes of disability studied. Compared with professional occupations (social class I), the relative risk (RR) of permanent work incapacity was 11.4 for partly skilled and unskilled occupations (class IV+V) (95% confidence interval [CI]: 5.2-28.0). The social class gradient in mortality was in the same direction as that in work incapacity although much less steep (RR class IV+V to class I = 1.6, 95% CI : 1.1-2.2). Survival without work incapacity at the time of the 65th birthday ranged from only 57% in construction workers and labourers to 89% in science and related professionals. Unemployment in Geneva was below 1.5% during almost all the study period. CONCLUSIONS: Medically-ascertained permanent work incapacity and survival without work incapacity have shown considerably greater socioeconomic differentials than the mortality differentials. (+info
A method for calculating age-weighted death proportions for comparison purposes.
OBJECTIVE: To introduce a method for calculating age-weighted death proportions (wDP) for comparison purposes. MATERIALS AND METHODS: A methodological study using secondary data from the municipality of Sao Paulo, Brazil (1980-1994) was carried out. First, deaths are weighted in terms of years of potential life lost before the age of 100 years. Then, in order to eliminate distortion of comparisons among proportions of years of potential life lost before the age of 100 years (pYPLL-100), the denominator is set to that of a standard age distribution of deaths for all causes. Conventional death proportions (DP), pYPLL-100, and wDP were calculated. RESULTS: Populations in which deaths from a particular cause occur at older ages exhibit lower wDP than those in which deaths occur at younger ages. The sum of all cause-specific wDP equals one only when the test population has exactly the same age distribution of deaths for all causes as that of the standard population. CONCLUSION: Age-weighted death proportions improve the information given by conventional DP, and are strongly recommended for comparison purposes. (+info
Comparison of active and cancer registry-based follow-up for breast cancer in a prospective cohort study.
The authors compared the relative effectiveness of two distinct follow-up designs in prospective cohort studies--the active approach, based on direct contact with study subjects, and the passive approach, based on record linkages with population-based cancer registries--utilizing available information from the New York University Women's Health Study (WHS) and the New York State Cancer Registry (NYSCR). The analyses were limited to breast cancer cases identified during the period 1985-1992, for which follow-up was considered reasonably complete by both the WHS and the NYSCR. Among 12,947 cohort members who reported a New York State address, 303 pathologically confirmed cases were identified through active follow-up and 284 through record linkage. Sixty-three percent of cancers were identified by both sources, 21% by the WHS only, and 16% by the NYSCR only. The agreement was appreciably better for invasive cancers. The percentage of cases identified only by the NYSCR was increased among subjects whose active follow-up was incomplete, as well as among nonwhites, obese patients, and parous patients. This suggests that relying on either type of follow-up alone may introduce certain biases in evaluating risk factors for breast cancer. Combining both approaches appears to be a better strategy in prospective cohort studies. (+info
Reliability of information on physical activity and other chronic disease risk factors among US women aged 40 years or older.
Data on chronic disease risk behaviors and related variables, including barriers to and attitudes toward physical activity, are lacking for women of some racial/ethnic groups. A test-retest study was conducted from July 1996 through June 1997 among US women (n = 199) aged 40 years or more who were white, black, American Indian/Alaska Native, or Hispanic. The sample was selected and interviews were conducted using a modified version of the methods of the Behavioral Risk Factor Surveillance System. For behavioral risk factors such as physical inactivity, smoking, and low fruit and vegetable consumption, group prevalences were generally similar between interviews 1 and 2. However, kappa values for selected physical activity variables ranged from 0.26 to 0.51 and tended to be lower for black women. Discordance was low for variables on cigarette smoking and exposure to environmental tobacco smoke (kappa = 0.64-0.92). Discordance was high (kappa = 0.33) for low consumption of fruits and vegetables. Additional variables for barriers to and access to exercise ranged widely across racial/ethnic groups and in terms of measures of agreement. These methods illustrate an efficient way to sample and assess the reliability of data collected from women of racial/ethnic minority groups. (+info