Untersuchung ausgew?hlter Oberfl?chen-, Grund- und?Bodenwasserproben auf Perchlorat in Deutschland: Erste?Ergebnisse

Perchlorate is a component found in solid rocket fuels, explosives, fireworks, and road flares. In addition, perchlorate is a minor component of natural salt deposits in semiarid and arid regions. Discharge and storage areas as well as accidents are potential sources for perchlorate contamination of aquatic systems. Perchlorate has been detected in surface water and groundwater from several places worldwide. The aim of this study is to evaluate whether perchlorate occurs in surface water, groundwater, or soil leachate at selected sites in Germany. These sites include surface water from a military base in southern Germany, groundwater from a production site, and groundwater and soil leachate from a location where fireworks shows are performed regularly. Results show that perchlorate was detected in all surface water and groundwater samples with values around 1???g/l. Highest values (up to 15,000???g/l) were detected in pore waters of the ??Maifeld?? area in Berlin where soil was sampled immediately after a fireworks show.     

Sampling-rate calibration for rapid and nonlethal monitoring of organic contaminants in fish muscle by solid-phase microextraction

Solid-phase microextraction (SPME) is a promising technique for determining organic contaminants within biotic systems. Existing in vivo SPME-kinetic calibration (SPME-KC) approaches are unwieldy due to the necessity of predetermining a distribution coefficient for the analyte of interest in the tissue and the preloading of a calibrating compound to the fiber. In this study, a rapid and convenient SPME alternative calibration method for in vivo analysis, termed SPME-sampling rate (SPME-SR) calibration, was developed and validated under both laboratory and field conditions to eliminate such presampling requirements. Briefly, the SPME probe is inserted into tissue, in this study fish dorsal-epaxial muscle, for 20 min allowing the concentrations of target analytes in the fish muscle to be determined by the extracted amount of analyte and the predetermined sampling rates. Atrazine, carbamazepine, and fluoxetine were detected nonlethally in the low ppb levels within fish muscle, with both laboratory and field-derived results obtained by in vivo SPME-KC comparable (within a factor of 1.27) to those obtained by lethal sampling followed by tissue liquid extraction. The technique described in this study represents an important advance which broadens the application of SPME in vivo sampling technology.     

A survey of physics and dosimetry practice of permanent prostate brachytherapy in the United States

PURPOSE: To obtain data with regard to current physics and dosimetry practice in transperineal interstitial permanent prostate brachytherapy (TIPPB) in the U.S. by conducting a survey of institutions performing this procedure with the greatest frequency. METHODS AND MATERIALS: Seventy brachytherapists with the greatest volume of TIPPB cases in 1995 in the U.S. were surveyed. The four-page comprehensive questionnaire included questions on both clinical and physics and dosimetry practice. Individuals not responding initially were sent additional mailings and telephoned. Physics and dosimetry practice summary statistics are reported. Clinical practice data is reported separately. RESULTS: Thirty-five (50%) surveys were returned. Participants included 29 (83%) from the private sector and 6 (17%) from academic programs. Among responding clinicians, 125I (89%) is used with greater frequency than 103Pd (83%). Many use both (71%). Most brachytherapists perform preplans (86%), predominately employing ultrasound imaging (85%). Commercial treatment planning systems are used more frequently (75%) than in-house systems (25%). Preplans take 2.5 h (avg.) to perform and are most commonly performed by a physicist (69%). A wide range of apparent activities (mCi) is used for both 125I (0.16-1.00, avg. 0.41) and 103Pd (0.50-1.90, avg. 1.32). Of those assaying sources (71%), the range in number assayed (1 to all) and maximum accepted difference from vendor stated activity (2-20%) varies greatly. Most respondents feel that the manufacturers criteria for source activity are sufficiently stringent (88%); however, some report that vendors do not always meet their criteria (44%). Most postimplant dosimetry imaging occurs on day 1 (41%) and consists of conventional x-rays (83%), CT (63%), or both (46%). Postimplant dosimetry is usually performed by a physicist (72%), taking 2 h (avg.) to complete. Calculational formalisms and parameters vary substantially. At the time of the survey, few institutions have adopted AAPM TG-43 recommendations (21%). Only half (50%) of those not using TG-43 indicated an intent to do so in the future. Calculated doses at 1 cm from a single 1 mCi apparent activity source permanently implanted varied significantly. For 125I, doses calculated ranged from 13.08-40.00 Gy and for 103Pd, from 3.10 to 8.70 Gy. CONCLUSION: While several areas of current physics and dosimetry practice are consistent among institutions, treatment planning and dose calculation techniques vary considerably. These data demonstrate a relative lack of consensus with regard to these practices. Furthermore, the wide variety of calculational techniques and benchmark data lead to calculated doses which vary by clinically significant amounts. It is apparent that the lack of standardization with regard to treatment planning and dose calculation practice in TIPPB must be addressed prior to performing any meaningful comparison of clinical results between institutions.     

Identification of a putative precursor to the major surface glycoprotein of Pneumocystis carinii

The major surface glycoprotein (MSG) of Pneumocystis carinii f. sp. carinii is a family of proteins encoded by a family of heterogeneous genes. Messenger RNAs encoding different MSGs each begin with the same 365-bp sequence, called the Upstream Conserved Sequence (UCS), which is in frame with the contiguous MSG sequence. The UCS contains several potential start sites for translation. To determine if translation of MSG mRNAs begins in the UCS, polyclonal antiserum was raised against the 123-amino-acid peptide encoded by the UCS. The anti-UCS serum reacted with a P. carinii protein that migrated at 170 kDa; however, it did not react with the mature MSG protein, which migrates at 116 kDa. A 170-kDa protein was immunoprecipitated with anti-UCS serum and shown to react with a monoclonal antibody against a conserved MSG epitope. To explore the functional role of the UCS in the trafficking of MSG, the nucleotide sequence encoding the UCS peptide was ligated to the 5' end of an MSG gene and incorporated into a recombinant baculovirus. Insect cells infected with the UCS-MSG hybrid gene expressed a 160-kDa protein which was N-glycosylated. By contrast, insect cells infected with a baculovirus carrying an MSG gene lacking the UCS expressed a nonglycosylated 130-kDa protein. These data suggest that in P. carinii, translation begins in the UCS to produce a pre-MSG protein, which is subsequently directed to the endoplasmic reticulum and processed to the mature form by proteolytic cleavage.     

An automated film masking and illuminating system versus conventional radiographic viewing equipment: a comparison of observer performance

RATIONALE AND OBJECTIVES: We compared observer performance in the interpretation of radiographs using an automated film masking and illuminating system (AFIS) with performance using standard radiographic viewing equipment. METHODS: Observer performance was compared in three ways. In the first method, a radiographic pattern of vertical bars of varying conspicuity was shown to 11 subjects with use of the two different viewing systems. Subjects were not allowed to use a brightlight or handle the film. We then performed a receiver operating characteristic (ROC) study to compare observer accuracy in detection of low-contrast targets. ROC methodology was also used in the third portion of our study to compare the accuracy of interpretation of cervical spine radiographs by six radiologists. In both the second and third portions of our study, film handling and use of a bright-light was permitted to simulate clinical circumstances. RESULTS: As a group, observers performed significantly better using the AFIS in the first (P < .001) and second (P < .05) portions of our study. There was no significant difference in performance in interpretation of cervical spine radiographs between the two viewing systems. CONCLUSION: The AFIS enhanced low-contrast perception, but further research is needed to determine its ideal clinical applications.     

Probing the structure of the diphtheria toxin channel. Reactivity in planar lipid bilayer membranes of cysteine-substituted mutant channels with methanethiosulfonate derivatives

Community development for health (CD4H) is defined as the mobilization of communities actually or potentially suffering from a health problem to eliminate its causes or alleviate its consequences. This paper links this with questions of social identity, focusing on issues of ethnicity and 'race', in health promotion. When combined with notions of ethnicity and 'race'. CD4H is frequently a reaction to inequalities which are communally experienced and believed to increase risk of ill-health for the group. This paper theorizes the link between communal experience and activity to promote health, by drawing on sociological theory linking structure and agency. It examines how discourses of belonging and exclusion are enacted in struggles for health. Via examples from the Caribbean and the UK, instances of 'identity politics' in CD4H are identified, viewed as the use of essentialist, binary notions of self and other in the attempt to gain an advantage over the other. It is argued that such instances should not be considered in isolation, but should be viewed as responses to experience, particularly, in the UK context, the experience of racism in the Health Service.     

Increased left ventricular systolic function in insulin dependent diabetic patients with normal albumin excretion

Alterations in cardiovascular function may be an aetiological factor for the development of microalbuminuria in patients with insulin-dependent diabetes mellitus. We studied cardiac function with echocardiography in relation to the degree of albuminuria in 27 insulin-dependent diabetes mellitus patients and 13 healthy subjects. Patients were grouped according to urinary albumin excretion: <20 microg x min(-1) (normoalbuminuric), and 20 to 200 microg x min(-1) (microalbuminuric). None were or had been treated with cardiovascular drugs. The normoalbuminuric patients had a higher heart rate, mean velocity of circumferential shortening, stroke velocity index (a measure of contractility), and aortic peak velocity than controls. No difference in diastolic function was present. In the microalbuminuric group, the stroke velocity index was comparable to values observed in healthy subjects. The increased systolic performance (heart rate and contractility) may contribute to the renal hyperperfusion and glomerular hyperfiltration observed in insulin-dependent diabetes mellitus patients before the development of micro- and in turn macroalbuminuria. The possible cause effect mechanisms should be further studied, as preventive medical treatment of the hypercontractile heart is possible. In conclusion, cardiac contractility is increased in insulin-dependent diabetes mellitus patients with normoalbuminuria and returns to levels observed in healthy subjects when microalbuminuria develops.     

Interpreting personality profiles across cultures: bilingual, acculturation, and peer rating studies of Chinese undergraduates

Prior research (R.R. McCrae, P.T. Costa, & M.S. Yik, 1996) using a Chinese translation of the Revised NEO Personality Inventory suggested substantial differences between Hong Kong and North American undergraduates. Study 1, with a sample of bilingual Hong Kong students (N = 162), showed that prior findings were not due simply to the translation. Study 2, with undergraduates of European and Chinese ancestry living in Canada (N = 633), suggested that more of the differences were cultural in origin. Study 3, which used peer ratings of Chinese students (N = 99), replicated most Study 2 results, suggesting that exposure to Canadian culture increased openness, cheerfulness, and prosocial behavior and attitudes. Differences in sense of competence and vulnerability to stress appeared to be due to different cultural standards for judging these traits. Together, the 3 studies illustrate an integrated approach to interpreting personality differences across cultures.     

平台运动引起Bragg海浪谱的展宽及其压缩方法

基于运动叠加原理，推导了以Ｄｏｐｐｌｅｒ频率表征的雷达平台运动条件下高频段海浪杂波的运动方程及由平台运动引起的Ｂｒａｎｎ海浪谱的展宽式，给出了受平台运动调制的Ｂｒａｇｇ浪回波与目标信号在Ｄｏｐｐｌｅｒ域里的二阶模糊关系和动用ＳＴ－ＷＤ（Ｓｈｏｒｔ Ｔｉｍｅ Ａｖｅｒａｇｅ Ｗｉｇｎｅｒ－Ｖｉｌｌｅ Ｄｉｓｔｒｉｂｕｔｉｏｎ；短时间平均Ｗｉｇｎｅｒ－Ｗｉｌｌｅ分布）技术对一阶海浪回波信号的高频相位进