Reference values and human biological monitoring values for environmental toxins. Report on the work and recommendations of the Commission on Human Biological Monitoring of the German Federal Environmental Agency

This article describes the working principles and working procedures of the Commission on Human Biological Monitoring, which was established in 1993 as a joint commission of the Federal Health Office (Bundesgesundheitsamt) and the Federal Environmental Agency (Umweltbundesamt) in Germany. One of the main tasks of the commission is to develop scientifically based criteria for the application of human biological monitoring and for the evaluation of human monitoring data in environmental medicine. In principle, two different kinds of criteria are recommended: (a) reference values and (b) human biological monitoring values (HBM values). Reference values are intended to indicate the upper margin of the current background exposure of the general population to a given environmental toxin at a given time. Reference values can be used to identify subjects with an increased level of exposure (in relation to background exposure) to a given environmental toxin. However, reference values do not represent health-related criteria for the evaluation of human biological monitoring data. HBM values are derived from human toxicology and epidemiology studies and are intended to be used as a basis for a health-related evaluation of human biological monitoring data. Usually the commission recommends two different HBM values: HBM I, the concentration of an environmental toxin in a human biological material (usually blood, serum, plasma, or urine) below which there is--according to the knowledge and judgement of the commission--no risk for adverse health effects in individuals of the general population: and HBM II, the concentration of an environmental toxin in a human biological material (usually blood, serum, plasma, or urine) above which there is--according to the knowledge and judgement of the commission and with regard to the environmental toxin under consideration--an increased risk for adverse health effects in susceptible individuals of the general population. The HBM I value can be considered a kind of alert value (from the toxicological point of view), whereas the HBM II value represents a kind of action level, at which attempts should be undertaken to reduce the level of exposure immediately and to carry out further medical examinations. Values between HBM I and HBM II should be considered a warning signal of the need to control the analytical measurement and to reduce the level of exposure of the concerned individual as reasonably as is achievable. At present, reference and HBM values are available for lead in blood, for cadmium and mercury in blood and urine, and for pentachlorophenol in plasma/serum and urine. Reference values have been established for some polychlorinated biphenyls in blood and plasma as well as for hexachlorocyclohexane and hexacholorobenzene in blood as well as for some organochlorine in human milk.

alpha-Thrombin stimulates contraction of human bronchial rings by activation of protease-activated receptors

In a variety of diseases, inflammation causes microvascular leakage and activates thrombin. Evidence suggests that thrombin increases cytosolic calcium and stimulates human airway smooth muscle (ASM) cell proliferation. The receptor subtypes, however, that mediate the effects of thrombin on ASM cell growth or calcium mobilization remain unknown. In this study, we postulate that thrombin, which activates specific protease-activated receptors (PARs), also stimulates contraction of isolated human bronchial rings. With the use of intact human bronchial rings, alpha-thrombin (1-20 U/ml) increased bronchial tone to 19 +/- 3% of basal tone (P = 0.008; n = 5 experiments) and represents 20 +/- 8% of the maximum carbachol response. The EC(50) for thrombin-induced force generation was 12.2 U/ml (95% confidence interval 9.9-15.3 U/ml) and was not altered in bronchial rings that had the epithelium removed. In parallel experiments, a specific thrombin receptor-activating peptide (TRAP-14; 0.1-100 micromol/l) increased isometric tension to levels (14 +/- 2%; P = 0.0005; n = 5 experiments) comparable to those rings stimulated with thrombin. To characterize the receptors that mediate thrombin effects on human ASM, the expression of PARs in cultured human ASM cells was analyzed by RT-PCR analysis with specific primers for PARs. In these cells, PAR1 (thrombin receptor), PAR2, and PAR3 were expressed at comparable levels. In other experiments using immunocytochemical staining with specific antibodies to PAR1 and PAR2, we showed that ASM in bronchial rings and cultured ASM cells express PAR1 and PAR2 proteins. Taken together, these studies suggest that alpha-thrombin, in a receptor-specific and dose-dependent manner, induces contraction of bronchial rings in vitro. In addition, cultured human ASM cells express mRNA of PAR1, PAR2, and PAR3 and express PAR1 and PAR2 protein. Further studies are needed to determine whether alpha-thrombin plays a role in stimulating bronchoconstriction in inflammatory airway diseases such as asthma and bronchiolitis obliterans.

[Risk assessment of patients before lung surgery]

Lung resection offers the best prospect of long-term survival in patients with nonmetastatic pulmonary neoplasia. In view of the dismal prognosis of unresected bronchial cancer, surgical resection should be encouraged even in patients with reduced cardiopulmonary function. Accurate estimation of the postoperative cardiopulmonary function is therefore desirable to avoid (a) refusal of potentially curative treatment and (b) severe postoperative disability. The origins of post-resection morbidity and mortality are multifactorial. Thus, no single pulmonary function test or hemodynamic measurement can accurately and reliably predict postoperative cardiorespiratory complications. Criteria of functional operability should be based on percent of predicted value, so that patient's age, sex, and height will be taken into consideration. Exercise testing offers the advantage that both pulmonary and cardiac risk can be evaluated simultaneously. The high predictive value of maximal oxygen uptake (VO2max) in assessing postoperative morbidity and mortality is established. The calculation of predicted postoperative lung function (ppo) is of importance. The postoperative values for the forced expiratory volume in one second (FEV1-ppo), the transfer factor (TL,CO-ppo), and VO2max-ppo can be predicted by using the same formula. Patients with nearly normal lung function (FEV1, TL,CO > 75% predicted) and no concomitant cardiac disease can undergo lung resection right up to pneumonectomy without further diagnostic procedures. In the others, FEV1-ppo and TL,CO-ppo should be estimated first by taking into account the number of segments to be resected. Patients with values < 30% predicted are usually regarded as being inoperable, whereas values > 40% predicted qualify for resection without the need for further diagnostics. VO2max < 10 ml/kg/min or < 40% predicted are prohibitive for surgery. If VO2max is > 20 ml/kg/min or > 75% predicted, functional operability without limitation is given. For those cases where diagnostic uncertainty still remains, FEV1-ppo, TL,CO-ppo, and VO2max-ppo can be calculated by means of quantitative lung scans. Patients with either FEV1-ppo and TL,CO-ppo < 30% predicted or VO2max-ppo < 8 ml/kg/min or < 35% predicted are deemed inoperable.

[Evaluation of preoperative functional status in patients with lung cancer]

In view of the dismal prognosis of unresected bronchial cancer, surgical resection should be encouraged even in patients with borderline cardiopulmonary function. Accurate estimation of the cardiopulmonary reserve is therefore desirable to avoid denying potentially curative treatment on the on hand and severe postoperative disability on the other. Various parameters (lung volumes, gas exchange, pulmonary hemodynamics, exercise endurance) are reviewed concerning their predictive values to evaluate functional operatibility. No ideal test exists. During exercise both pulmonary and cardiac risk can be evaluated simultaneously. The high predictive value of maximal oxygen uptake to assess postoperative morbidity and mortality is established. The postoperative values for the forced expiratory volumes, the transfer factor, and maximal oxygen uptake can be predicted by means of quantitative lung scans. A new four-stage algorithm for the functional evaluation is presented. Patients with normal lung function and exercise electrocardiography can undergo lung resection up to a pneumonectomy without further diagnostic procedures. In others, first the predicted postoperative values of forced expiratory volume and transfer factor should be estimated by taking into account the number of segments to be resected. Patients with values < 30% predicted are regarded as inoperable, whereas values > 40% predicted quality for resection without the need for further diagnostics. Patients with values between 30-40% predicted are further differentiated with cardiopulmonary exercise testing and for those cases where diagnostic uncertainty still remains, predicted postoperative values can be calculated using quantitative lung scans.

Preoperative staging of esophageal carcinoma: miniprobe sonography versus conventional endoscopic ultrasound in a prospective histopathologically verified study

BACKGROUND AND STUDY AIMS

Endosonographic staging of esophageal carcinoma may be limited by non-traversable tumor stenoses. Dilation of malignant esophageal strictures carries a significant risk of esophageal perforation. We therefore evaluated the use of ultrasonic miniprobes in the staging of stenotic esophageal carcinoma compared with conventional endoscopic ultrasound.

PATIENTS AND METHODS

In a blinded, prospective study, which included histopathological evaluation, 53 consecutive patients (43 male, 10 female, mean age 61 years) with stenosing esophageal carcinomas were examined preoperatively. Endosonography was done using the optical GF-UM3 echo endoscope. If tumor strictures were not traversable with this instrument, a blind esophagoprobe, the MH-908 was used for endosonography. Miniprobe sonography (MPS) was done during esophagoscopy in all patients. The various imaging modalities were assessed in terms of complete tumor traversability and correct tumor staging. Every patient underwent surgical tumor resection.

RESULTS

MPS of the esophagus and proximal parts of the stomach was possible in all 53 patients without prior dilation of tumor stenoses. Endosonography with the GF-UM3 instrument was precluded in 23 patients (43.4%) while in 20 of the latter patients the MH 908 esophagoprobe could be passed through tumor stenoses. The overall accuracy rates for depth of tumor infiltration (T) staging were: 62% (31/50) for endosonography (GF-UM3 plus esophagoprobe) and 86.8% (46/53) for MPS. The accuracy rates for T staging in tumors traversable both with the GF-UM3 echo endoscope and with miniprobes were 56.7% (17/30) for GF-UM3 and 80% (24/30) for MPS. The accuracy rates for T staging in tumors traversable only with the MH-908 esophagoprobe and with miniprobes were 70% (14/20) for the MH-908 and 95% (19/20) for MPS. With regard to the presence or absence of peri-esophageal metastatic lymph nodes (N staging), the accuracy rates were 83% (25/30) for MPS and 70% (21/30) for the GF-UM3, and 80% (16/20) for MPS and 70% (14/20) for the MH-908.

CONCLUSION

Compared with conventional endosonography using 7.5-MHz large diameter instruments, MPS enables: a) safe passage through high-grade malignant esophageal strictures, achieving b) higher accuracy rates for T staging, and c) similar rates for N staging. The use of MPS can also represent an improvement in the comfort and safety of patients. Moreover, miniprobe sonography is highly cost-effective compared with conventional endosonography. Thus, MPS appears to be a valuable addition to the armamentarium for staging esophageal carcinoma.

Investigation of spatially resolved light absorption in a spark-ignition engine fueled with propane/air

UV absorption in the combustion phase of spark-ignition engines strongly influences laser-induced-fluorescence measurements and flame-emission techniques because of the attenuation of a laser and/or signal light. This absorption was assessed with spatial, spectral, and temporal resolutions in an optically accessible research engine. Absorption was measured along a line for different crank-angle positions throughout the combustion phase of the engine by use of spectrally resolved transmittance measurements of both broadband illumination from a deuterium lamp and emission of laser-excited hot oxygen. Evaluating the spatial patterns of absorptivity revealed that no increased absorption can be attributed to the flame-front region and that homogeneous absorption cross sections for the whole burned-gas region can be assumed. The temporal change of absorption was shown to depend on the pressure effect with only negligible changes in absorption cross sections. Results obtained from the absorption measurements are applied for spatially resolved corrections of two-dimensional laser-induced-fluorescence measurements of NO concentration fields obtained under different operating conditions.

Quantification of NO A-X (0, 2) laser-induced fluorescence: investigation of calibration and collisional influences in high-pressure flames

Laser-induced-fluorescence techniques have been used successfully for quantitative two-dimensional measurements of nitric oxide. NO A-X(0, 2) excitation at 248 nm recently found applications in internal-combustion engines. We assess the collisional processes that influence quantification of signal intensities in terms of saturation, rotational energy transfer, and line broadening, using laminar high-pressure methane/air and n-heptane/air flames at pressures as high as 80 bars (8 x 10(6) Pa). A calibration method that is applicable in technical combustion systems based on addition of NO to the burning flame is investigated for various air/fuel ratios and pressures and yields information about the influence of NO reburn processes.

Rapid and sensitive determination of catecholamines and the metabolite 3-methoxy-4-hydroxyphen-ethyleneglycol using HPLC following novel extraction procedures

In the present study assays were improved for the determination of free catecholamines and 3-methoxy-4-hydroxyphenethyleneglycol (MHPG), the major metabolite of peripheral and central noradrenaline. The compounds were extracted by a fluid phase extraction: a diphenyl boric acid method for the purification of catecholamines and an ethyl acetate extraction for MHPG were used, respectively. High-performance liquid chromatography with electrochemical detection was employed for quantitative analysis. In previous studies, significant differences between plasma concentrations of these substances in normal volunteers and hospital patients were demonstrated. Therefore, we established valid reference values for a hospital population. Blood and urine samples of 59 patients without disorders and medication affecting catecholamine synthesis and metabolism or the activity of the sympatho-adrenal system were collected and analyzed for free and total (free plus conjugated) MHPG, noradrenaline (NA), adrenaline (A) and dopamine (DA); total MHPG was assayed after enzymatic hydrolysis of conjugates. Our data clearly demonstrate that these methods are sensitive, specific, rapid, and can easily be standardized. The intra- and inter-assay precision were high (CV 2.6-5.3% and 4.3-6.9% for plasma, CV 3.8-4.9% and 5.1-8.2% for urine, respectively). For plasma, the mean concentrations +/- SD were determined to be 20.82+/-4.70 pmol/ml for free MHPG, 68.43+/-16.21 pmol/ml for total MHPG, 2.11+/-0.24 pmol/ml for NA and 0.31+/-0.08 pmol/ml for A. For 24h-urine the mean concentrations +/-SD were determined to be 0.44+/-0.13 mmol/24h for free MHPG, 8.79+/-2.13 mmol/24h for total MHPG, 169.8+/-58.25 nmol/24h for NA, 62.19+/-21.79 nmol/24h for A and 757.2+/-382.6 nmol/24h for DA. In summary, these novel and rapid methods can clearly be employed in a routine clinical setting.

Regulation of the Tribolium homologues of caudal and hunchback in Drosophila: evidence for maternal gradient systems in a short germ embryo

In short germ embryos, the germ rudiment forms at the posterior ventral side of the egg, while the anterior-dorsal region becomes the extra-embryonic serosa. It is difficult to see how an anterior gradient like that of bicoid in Drosophila could in these embryos be directly involved in patterning of the germ rudiment. Moreover, since it has not yet been possible to recover a bicoid homologue from any species outside the diptera, it has been speculated that the anterior bicoid gradient could be a late addition during insect evolution. We addressed this question by analysing the regulation of potential target genes of bicoid in the short germ embryo of Tribolium castaneum. We demonstrate that homologues of caudal and hunchback from Tribolium are regulated by Drosophila bicoid. In Drosophila, maternal caudal RNA is translationally repressed by bicoid. We find that Tribolium caudal RNA is also translationally repressed by bicoid, when it is transferred into Drosophila embryos under a maternal promoter. This strongly suggests that a functional bicoid homologue must exist in Tribolium. The second target gene, hunchback, is transcriptionally activated by bicoid in Drosophila. Transfer of the regulatory region of Tribolium hunchback into Drosophila also results in regulation by early maternal factors, including bicoid, but in a pattern that is more reminiscent of Tribolium hunchback expression, namely in two early blastoderm domains. Using enhancer mapping constructs and footprinting, we show that caudal activates the posterior of these domains via a specific promoter. Our experiments suggest that a major event in the evolutionary transition from short to long germ embryogenesis was the switch from activation of the hunchback gap domain by caudal to direct activation by bicoid. This regulatory switch can explain how this domain shifted from a posterior location in short germ embryos to its anterior position in long germ insects, and it also suggest how an anterior gradient can pattern the germ rudiment in short germ embryos, i.e. by regulating the expression of caudal.

Physiological and neurochemical aspects of corticotropin-releasing factor actions in the brain: the role of the locus coeruleus

Corticotropin-releasing factor (CRF) is both a major regulator of the hypothalamo-pituitary-adrenal (HPA) axis and the activity of the autonomic nervous system. Besides, it exerts numerous effects on other physiological functions such as appetite control, motor and cognitive behavior and immune function. The basis for these effects is constituted by its distribution in hypothalamic and extra-hypothalamic brain areas, the latter being represented by limbic structures such as the central nucleus of the amygdala or by brain stem neurons such as the locus coeruleus (LC) or nucleus of the solitary tract (NTS). The effects of CRF are mediated through recently described CRF-receptor subtypes, whose molecular biology, biochemistry and pharmacological regulation are discussed in detail. In the second part of this review, we will focus on the physiology of CRF-systems in the brain, with a particular emphasis on cardiovascular regulation, respiration, appetite control and stress-related behavior. Finally, the role of the locus coeruleus in the control of CRF-mediated behavioral activities is discussed. The interaction of noradrenergic and CRF-neurons clearly implies that CRF appears to directly activate LC neurons in a stressful situation, thus ultimately coordinating the bodily response to a stressful stimulus.

A caudal homologue in the short germ band beetle Tribolium shows similarities to both, the Drosophila and the vertebrate caudal expression patterns

We have isolated a homologue to the Drosophila caudal (cad) gene from the flour beetle Tribolium castaneum and have studied its expression pattern. The Tribolium caudal (Tc-cad) gene arrangement is unusual in that there is a partial duplication of the gene resulting in alternative transcripts with identical 5'-exons, but different 3'-exons encoding two different homeoboxes. Expression analysis was done by whole-mount in situ hybridization and by staining with an antibody raised against the N-terminal part of the protein that is common to both transcripts. At early stages we observe a homogeneously distributed maternal mRNA which is initially also translated throughout the embryo. A little later, a posterior to anterior CAD protein gradient is formed, very similar to that in Drosophila. However, because of the differences in the fate map between Drosophila and Tribolium, the CAD protein expression at blastoderm stage covers the prospective head and thoracic region and not the abdomen as in Drosophila. Expression of Tc-cad in the prospective abdomen is only seen during further germband growth where it becomes restricted to the growth zone in which the segments are formed. This expression is very similar to the growth zone expression in the somitogenic region seen for cad homologues in vertebrates. After the completion of the segmentation process Tc-cad expression becomes confined to a terminal stripe which resembles a similar stripe at late blastoderm stages in Drosophila.

[Stress osteotomy of the distal radius- and ulna metaphysis (Illarramendi procedure): an alternative treatment method in lunate necrosis]

The etiology of Kienböck's disease is still unknown. Many operative procedures, usually based on biomechanical considerations, are recommended. Based on known effects of core decompression procedures on bone, we present a technique of core decompression of the metaphysis of the distal radius and ulna (MCD) as an easy, alternative biologic treatment. Ten cases with a mean follow-up of 10.8 years are analyzed. All patients had significant postoperative pain relief and returned to their previous activities. At the time of follow-up, comparative motion of flexion-extension of the wrist averaged 74%, mean grip strength was 81% of the nonaffected side. Radiographic follow-up did not slow significant postoperative collapse of the lunate (p > 0.05). No correlation was observed between post-operative results and ulnar variance. MCD is a simple, low-risk procedure. Clinical and radiological outcome supports a theory of biologic rather than biomechanic mechanisms related to fracture healing, that stimulate regeneration of the avascular lunate and relieve symptoms. A primary vascular etiology of idiopathic avascular necrosis of the lunate seems to be likely.

[Evaluation of topical drugs with reference to indications. A selection]

Between 1988 and 1994 more than 40 monographs dealing with dermatologically relevant drugs have been published in an official German government publication, the "Bundesanzeiger". These monographs represent reviews compiled by independent dermatological and pharmaceutical authorities working together in an expert commission and most of their information has proved valid. Thus, knowledge of these official reviews could help physicians to decide about the use of many drugs. However, they are not well-known to doctors. With this brief summary we hope to make more physicians familiar with these important monographs published in the "Bundesanzeiger".

Preoperative bronchoscopic assessment of airway invasion by esophageal cancer: a prospective study

BACKGROUND

Bronchoscopy is frequently used to assess invasion of esophageal cancer into the tracheobronchial tree. Prospective studies evaluating the role of bronchoscopy in pretherapeutic staging of esophageal cancer are lacking.

STUDY OBJECTIVES

To evaluate the diagnostic utility of fiberoptic bronchoscopy for the assessment of airway involvement by esophageal carcinoma and its resectability.

PATIENTS AND METHODS

In a prospective study, we analyzed 150 bronchoscopies in 116 consecutive patients with potentially operable esophageal carcinoma, and correlated the findings with other staging modalities, intraoperative evaluation, and histopathologic data.

RESULTS

One unknown additional bronchial cancer was found. In 32% of bronchoscopies performed in patients with esophageal cancer located above the tracheal bifurcation, some macroscopic abnormality was detected in the trachea and main bronchi, with mobile protrusion of the posterior tracheal wall being the most frequent abnormality (20.7%). When compared with histologic results, normal macroscopic appearance of the trachea and main bronchi had a negative predictive value of 98.5%, but the positive predictive value of all macroscopic abnormalities for the diagnosis of airway involvement was low, particularly after radiation therapy. The overall accuracy of bronchoscopy with multiple brush cytology and biopsy sampling in proving or excluding airway invasion in patients with otherwise operable conditions was 95.8% (95% confidence interval, 88.3 to 99.1%). Bronchoscopy was the sole decisive staging procedure, resulting in exclusion from surgery because of airway invasion, in 9.7% of patients with otherwise potentially operable conditions. The results of bronchoscopy and CT were discordant in 40% of the patients; the specificity and positive predictive value were higher for bronchoscopy than for CT.

CONCLUSIONS

When performed as the last investigation in the staging workup, bronchoscopy with biopsy and brush cytology is a very accurate procedure in evaluating possible airway invasion of esophageal cancer; macroscopic findings alone are not reliable.

Cell proliferation in the livers of male mice and rats exposed to the carcinogen P-dichlorobenzene: evidence for thresholds

In a previous study, p-dichlorobenzene (pDCB), which is associated with tumorigenicity in male rat kidney and livers of mice of both genders, was found to produce acute increases in cell proliferation in those tissues. To determine whether sustained cell proliferation in the liver in susceptible species correlated with reported carcinogenic effects, we examined the effect of pDCB on cell proliferation in the livers and toxicity to the glutamine synthetase-expressing hepatocyte (GS+) subpopulation of male B6C3F1C3F1 mice and F344 rats. Mice were exposed for up to 4 weeks to 600, the maximally tolerated dose which increased liver tumors, 300 or 150 mg/kg. Rats were exposed to 300, 150 or 75 mg/kg for up to 4 weeks. In mice, the cumulative replicating fraction (CRF) in the livers of the high dose animals was significantly increased 16-fold at 1 week and 4-fold at 4 weeks. The CRF was also increased at 300 mg/kg at 1 week, but this subsided at 4 weeks. No increase was seen in the low dose group. In rats, the CRFs of the livers at 1 week were increased at 300 and 150 mg/kg, but returned to normal at 4 weeks. The size of the hepatic GS+ area was not affected in mice or in rats after 1 week of exposure, but comparable decreases were observed at all exposures at 4 weeks in mice. The data therefore suggest that sustained increases of cell division in the mouse liver may contribute to the increases in liver tumors. The transient increase in rat liver suggests that this is not sufficient to enhance tumor development. The absence of sustained increases of the CRFs at the low dose in mice, which was one-fourth of the hepatocarcinogenic dose, implies the existence of a threshold in pDCB hepatocarcinogenesis.

[Pyrethroids in house dust of the German housing population--results of 2 nationwide cross-sectional studies]

As a part of the German Environmental Surveys performed in 1985/86 (West Germany), 1990/91 (West Germany) and 1991/92 (East Germany), dust samples were collected in the households of about 1600 randomly selected adults (25 to 69 years) and an analysis of these samples was performed in respect of their content of 8 different pyrethroids and of the synergist piperonyl butoxide (PBO). In the 1990-92 survey about 90% of the samples contained permethrin in concentrations above the limit of quantification. This showed permethrin to be the most widespread of the 8 compounds investigated. The geometric mean of the permethrin content in domestic dust was 0.22 mg/kg. Only about 8% of the samples contained one or more of the other investigated substances (cyfluthrin, lambda-cyhalothrin, cypermethrin, alpha-cypermethrin, deltamethrin, empenthrin, d-phenothrin) in quantifiable amounts. About 76% of the samples contained quantifiable amounts of PBO. In East Germany the geometric mean of the PBO content (0.21 mg/kg) was significantly higher than in West Germany (0.07 mg/kg), but no difference for permethrin was found. Significant associations could be shown for the permethrin content and the application of biocides as well as for the PBO content and regional factors (size of community, type of dwelling area). Samples collected in 1985/86 (West Germany) showed a geometric mean for permethrin of 0.06 mg/kg and for PBO of 0.07 mg/kg. Comparing the values of 1985/86 and 1990/91, a significant increase can be observed for permethrin, whereas the PBO concentration remained constant.

The effect of lead in tap water on blood lead in children in a smelter town

Hettstedt, a city in eastern Germany with a long history of mining and smelting of non-ferrous ores, has multiple lead waste deposits and the remains of a former lead smelter and a copper-silver smelter. As part of a cross-sectional study, an analysis of lead concentrations in drinking water and in blood was undertaken to determine the impact of lead in drinking water on the internal burden of lead in children. The geometric mean of blood lead levels among children 5-14 years old was 35.0 micrograms/l with a 95% confidence interval (C.I.) of 33.4-36.7. The geometric mean of lead in the random tap water samples was 0.5 microgram/l (95% C.I., 0.5-0.6) and 0.7 microgram/l (95% C.I., 0.6-0.8) in the stagnant tap water samples. Blood lead levels were somewhat correlated with the random water measures but not the stagnant water measures (random sample: r = 0.12, P = 0.012; stagnant sample: r = 0.04, P = 0.396). After adjustment for relevant confounders, lead in drinking water (random sample) was not significantly associated with blood lead levels. Factors that were significantly associated with blood lead included gender, the city area of residence, lead in house dust, regular contact with dogs and dirtiness of the child after playing outdoors. Based on this study, lead in domestic tap water contributed little to the lead exposure of children in the lead contaminated region of Hettstedt.

Good practice in multimedia courseware development

The main goal of the European TALENT/ESPRIT project is to create a generic environment for developing multimedia courseware. The first phase of the project concerns itself with developing conversion tools for converting text based course material into multimedia format. The second phase of the project adds network support to the courseware in the form of the network tutoring and networked supply chain support. One year into the project specifications for developing multimedia have been made and can be found in the project's deliverables. Also a summary of good practice in multimedia courseware development has been drawn up. First phase demonstrators (converted text based courses) are currently being prepared. This article starts with a global overview of the TALENT project itself. In more detail an overview of best practice guidelines in multimedia courseware development will be given. The information shown was obtained from an extensive survey among experts in the field of computer based training. The survey was conducted early this year as part of one of the project's deliverables. Finally some comments will be made on a multimedia demonstrator which is currently under development at HISCOM.

[Clinical and endocrine diagnosis of pheochromocytoma]

Pheochromocytomas are catecholamine-producing tumors, representing one of the most important causes of secondary hypertension. The classification of these tumors considers both sporadic and familial forms, intra- and extraadrenal localization as well as the dignity. Familial pheochromocytomas are primarily seen under the conditions of multiple endocrine neoplasia, von Hippel-Lindau disease or neurofibromatosis type 1. The list of clinical symptoms includes hypertension, which can be both continuous or intermittent, headache, tachycardia and sweating. It is most important to standardize the pre-analytical procedures, i.e. control for sampling conditions and adequate choice of parameters in plasma or urine. For screening sensitive methods will be employed (free catecholamines in 24h-urine) and for confirmation of the diagnosis, specific procedures are performed (Clonidine test, MIBG-scintigraphy). The endocrinological and biochemical procedures are completed by molecular genetic techniques in familial pheochromocytoma.

Ventilation perfusion scintigraphy and lung function testing to assess metal stent efficacy

Stent implantation in malignant bronchial stenoses is a highly effective method of providing symptomatic relief by restoring bronchial patency. Whether an improvement in ventilatory conditions is paralleled by an increase in blood flow and gas exchange has not yet been determined.

METHODS

Fourteen patients with malignant, high-grade obstruction of bronchi who had metal stent implantation were investigated. Before the intervention and again 8 days afterward, both quantitative technegas ventilation and 99mTc-MAA perfusion scans (V/Q scans) and lung function tests were performed.

RESULTS

Stent implantation was successful in all patients, with a significant reduction in the degree of bronchial stenosis (pre-stent: 93% +/- 1.5%; post-stent: 16% +/- 3.5%). After stent implantation, ventilation scintigraphy revealed an improvement in tracer deposition by 65% (pre-stent: 37% +/- 8%; post-stent: 61% +/- 6%; p < 0.05) within the affected lung. A complementary increase of 71% by perfusion scintigraphy was obtained (pre-stent: 27% +/- 4%; post-stent: 46% +/- 5%; p < 0.01%). Based on scintigraphic criteria, stenting was successful in 93% (n = 13) of all patients. Lung function studies performed after the intervention showed significant improvement in vital capacity (VC, p < 0.01), forced expiratory volume in 1 sec (FEV1, p < 0.05), peak expiratory flow (PEF, p < 0.05), arterial oxygen (PaO2, p < 0.05) and carbon dioxide (PaCO2, p < 0.05) tension, and oxygen saturation (p < 0.05).

CONCLUSION

Stenting of malignant high-grade bronchial obstructions leads to an increase in bronchial patency and in activity distribution of both ventilation and perfusion scintigraphy of the affected lung, accompanied by significant improvement in lung function parameters.

Effects of beta 2-agonist- and dexamethasone-treatment on relaxation and regulation of beta-adrenoceptors in human bronchi and lung tissue

1. Long-term treatment with beta 2-adrenoceptor agonists can lead to a decreased therapeutic efficacy of bronchodilatation in patients with obstructive pulmonary disease. In order to examine whether or not this is due to beta-adrenoceptor desensitization, human bronchial muscle relaxation was studied in isolated bronchial rings after pretreatment with beta 2-adrenoceptor agonists. Additionally, the influence of pretreatment with dexamethasone on desensitization was studied. 2. The effect of beta 2-agonist incubation alone and after coincubation with dexamethasone on density and affinity of beta-adrenoceptors was investigated by radioligand binding experiments. 3. In human isolated bronchi, isoprenaline induces a time- and concentration-dependent beta-adrenoceptor desensitization as judged from maximal reduction in potency by a factor of 7 and reduction of 73 +/- 4% in efficacy of isoprenaline to relax human bronchial smooth muscle. 4. After an incubation period of 60 min with 100 mumol l-1 terbutaline, a significant decline in its relaxing efficacy (81 +/- 8%) and potency (by a factor 5.5) occurred. 5. Incubation with 30 mumol l-1 isoprenaline for 60 min did not impair the maximal effect of a subsequent aminophylline response but led to an increase in potency (factor 4.4). 6. Coincubation of dexamethasone with isoprenaline (120 min; 30 mumol l-1) preserved the effect of isoprenaline on relaxation (129 +/- 15%). 7. In radioligand binding experiments, pretreatment of lung tissue for 60 min with isoprenaline (30 mumol l-1) resulted in a decrease in beta-adrenoceptor binding sites (Bmax) to 64 +/- 1.6% (P < 0.05), while the antagonist affinity (KD) for [3H]-CGP-12177 remained unchanged. 8. In contrast, radioligand binding studies on lung tissue pretreated with either dexamethasone (30 mumol l-1) or isoprenaline (30 mumol l-1) plus dexamethasone (30 mumol l-1) for 120 min did not lead to a significant change of Bmax (160 +/- 22.1% vs 142.3 +/- 28.7%) or KD (5.0 nmol l-1 vs 3.5 nmol l-1) compared to the controls. 9. In conclusion, pretreatment of human bronchi with beta-adrenoceptor agonists leads to functional desensitization and, in lung tissue, to down-regulation of beta-adrenoceptors. This effect can be counteracted by additional administration of dexamethasone. Our model of desensitization has proved useful for the identification of mechanisms of beta-adrenoceptor desensitization and could be relevant for the evaluation of therapeutic strategies to counteract undesirable effects of long-term beta-adrenoceptor stimulation.

Laser-induced-fluorescence detection of nitric oxide in high-pressure flames with A-X(0, 2) excitation

Laser-induced fluorescence techniques have been used successfully for quantitative two-dimensional measurements of nitric oxide. The commonly applied D-X(0, 1) or A-X(0, 0) schemes are restricted to atmospheric-pressure flames and engines driven with gaseous fuels because of strong attenuation of the exciting laser beam by combustion intermediates. The properties of a detection scheme for which excitation in the nitric oxide A-X(0, 2) band was used were investigated. We discuss the advantages of the A-X(0, 2) system (excited at 247.95 nm) based on measurements in laminar premixed methane/air flames at 1-40 bars.

Factors affecting internal mercury burdens among eastern German children

Internal burdens of mercury were evaluated among 5- to 14-y-old eastern German children in the heavily polluted areas of Bitterfeld, a center of chemical production and coal mining, and Hettstedt, a region of nonferrous metal smelting and mining. We compared blood and urine mercury concentrations in these children with mercury burdens in children who lived in a control area. The unadjusted geometric means of mercury levels in the total group were 0.25 microg/l (95% confidence interval = 0.24, 0.27) in blood and 0.36 microg mercury/g creatinine (95% confidence interval = 0.33, 0.39) in urine. Mercury levels in blood and urine were not significantly higher in children who occupied the two polluted areas, compared with children in the control area. The most significant factor that affected urinary mercury levels was the number of dental amalgam fillings; 27% of the variance in the regression model was explained by the presence of these fillings.

The internal burden of lead among children in a smelter town--a small area analysis

Hettstedt, a city in former East Germany with a history of mining and smelting of nonferrous ores, has multiple lead waste deposits and the remains of a former lead and copper-silver smelter. A small-area analysis of lead concentrations in blood and in household dust was undertaken in a cross-sectional study to determine if children living near the sources had particularly high burdens of lead. The overall geometric mean of the region was 38.0 micrograms Pb/liter blood with a 95% confidence interval (CI) of 36.5-39.5. The burden of lead among children living in the region containing the lead tailings piles and adjacent smelters was almost twice as high (77.4 micrograms Pb/liter blood; 95% CI 65.0-92.0). It decreased in the areas farther northeast from the smelter. Lead levels in the children residing in areas southwest of the smelters were not appreciably elevated. The same pattern was found in house dust lead concentrations. This analysis helped target areas where follow-up is needed and found that not only distance from lead sources, but also meteorological factors played an important role in lead exposure.

Diethylnitrosamine exposure-responses for DNA damage, centrilobular cytotoxicity, cell proliferation and carcinogenesis in rat liver exhibit some non-linearities

The exposure-responses for several effects of limited exposures to diethylnitrosamine (DEN) in the livers of male Fischer 344 rats were measured and phenobarbital promotion was used to enhance expression of initiation of carcinogenesis. Five doses ranging from a cumulative total of 0.5 to 4 mmol DEN per kg body weight were given as weekly i.p. injections for 10 weeks. This was followed by 4 weeks recovery, after which the groups were maintained on either a basal diet or 0.05% phenobarbital (PB) to promote liver tumor development. All doses of DEN produced ethylation in liver DNA, which increased with dose. Indicative of toxicity, the centrilobular zone of glutamine synthetase-positive hepatocytes was reduced in relationship to exposure up to a cumulative exposure of 3 mmol/kg. The two lower exposures to DEN produced no increase in cell proliferation, whereas higher exposures resulted in marked increases, approximately 4-fold between 1.0 and 2.0 mmol/kg cumulative. At the end of the recovery period (14 weeks), hepatocellular altered foci (HAF), which expressed the placental form of glutathione S-transferase, were induced by all exposures, with an increase of approximately 4-fold between the exposures of 1.0 and 2.0 mmol/kg being the greatest. In rats maintained on basal diet or PB for 24 weeks after exposure, HAF increased further and with exposures of 2.0 mmol/kg and above, all rats developed hepatocellular carcinomas. With 1.0 mmol/kg, no liver tumor occurred in 12 rats without promotion, whereas in those given PB, two adenomas and two carcinomas were present in 12 rats. At the lowest exposure of 0.5 mmol/ kg, no tumor occurred in rats on basal diet, although HAF increased approximately 7-fold. With PB promotion, only one adenoma developed in 12 rats and HAF increased another 2-fold. Thus, the findings document non-linearity for some of the effects of DEN and a near no-effect level for initiation of promotable liver neoplasms at the lowest exposure in spite of a substantial induction of HAF.

Effect of epinine on tension of human renal arteries

BACKGROUND

The present study aimed to characterize the effects of epinine, the active metabolite of ibopamine on tension development in human renal arteries.

METHODS AND RESULTS

Experiments were performed on isolated human renal arteries rings obtained during surgery due to kidney tumors (n = 12). Epinine concentration-dependently relaxed isolated precontracted (PGF2 alpha) human renal artery rings (P < 0.05) in the presence of phentolamine, as effectively (epinine -30 +/- 4 mN, dopamine -31 +/- 5 mN) and with the same potency as dopamine (epinine EC50 0.7 mumol/l (0.4-1.2 mumol/l), dopamine 0.5 mumol/l (0.2-1.7 mumol/l). This effect was antagonized by the specific D1-receptor-antagonist SCH 23390. Effective beta-adrenoceptor antagonistic concentrations of propranolol did not affect epinine-induced vasorelaxation. In the absence of alpha- and beta-adrenoceptor-antagonists the potency of epinine to contract renal artery rings was significantly higher compared to dopamine indicating a higher affinity of epinine to alpha-adrenoceptors.

CONCLUSION

The present study provides evidence for direct vasodilatory effects of epinine via activation of D1-receptors on human renal arteries.

Activation of noradrenergic neurons in the locus coeruleus by corticotropin-releasing factor. A microdialysis study

In the present study the effects of different doses of corticotropin-releasing factor (CRF) and the CRF antagonist alpha-helical CRF on locus coeruleus (LC) neurons were studied in anesthetized male Wistar rats. To monitor the release of noradrenaline (NA) and its metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), a microdialysis probe was implanted into the parietal cortex, a major projection area of the LC. Saline, 0.17, 0.51 nmol CRF and a combination of 5.1 nmol alpha-helical CRF and 0.51 nmol CRF were applied to the LC via a fused silica capillary. While both doses of CRF augmented NA in parietal cortex dialysates (0.51 nmol CRF: from 0.0206 to 0.0266 pmol/sample; 0.17 nmol CRF: from 0.0147 to 0.0170 pmol/sample), saline did not affect NA concentration. The metabolite MHPG also increased, but in a more prolonged time course. The antagonist alpha-helical CRF attenuated the CRF effects. The increase of extraneuronal NA concentration monitored in the cortical samples indicates an augmented depolarization rate of noradrenergic LC neurons. This clearly demonstrates the activation of these neurons by CRF, suggesting physiological interactions of CRF and noradrenergic neurons.

Arsenic burden among children in industrial areas of eastern Germany

The internal burden of arsenic among 5- to 14-year-old eastern German children in the heavily polluted areas of Hettstedt, a region of smelting and copper mining, and Bitterfeld, a center of chemical production and coal mining, was compared with that in a control area (Zerbst) by means of urinary arsenic concentrations in 1992-94. The unadjusted geometric mean among the 950 children was significantly higher in Hettstedt (5.1 micrograms/l; 95% C.I. 4.8-5.5) but not in Bitterfeld (4.3 micrograms/l; 95% C.I. 3.7-4.9) compared with the control area (4.0 micrograms/l; 95% C.I. 3.5-4.5). This difference persisted after adjustment for relevant confounders. Despite these regional differences, recent fish consumption was as strongly associated with urinary arsenic levels (42% increase, 95% C.I. 18-71%). Additionally, although the geometric mean among the children in Hettstedt (4.8 micrograms As/g creatinine; 95% C.I. 4.5-5.1) was higher than that found in an environmental survey of eastern German children (3.60 micrograms As/g creatinine; 95% C.I. 3.06-4.24), it was similar to that found among western German children (4.59 micrograms As/g creatinine; 95% C.I. 4.20-5.02). This suggests that the arsenic contamination in Hettstedt is not substantially increasing the internal burden of arsenic among children above that found in other German children.

Regionalization of donor organ procurement: first experiences in southern Bavaria and results of a regional donor hospital survey

In order to improve organizational, qualitative, and economic aspects of organ procurement, a model of regionalization was established in the local area of southern Bavaria, as from September 1993, with the following characteristics. A collaborative 24 h-duty schedule with surgeons from all active regional transplant programs. Surgeons are grouped according to their operative qualification level: (1) Group I, capable of retrieving all abdominal organs (liver, pancreas, kidney), (2) Group II, capable of removing kidneys, and (3) Group III, surgical assistance in procurement procedures. All donor organs in the local region are explanted by the local team and foreign recipient centers are supplied with the organs removed by a standardized technique. Only three times during the first, and not once during the second year, did a foreign team insist on traveling to our region to perform a liver retrieval. A survey clearly documented univocal acceptance of this model by donor hospital executives. Simplified organization and less disturbance in operating theaters were among the most frequent arguments in favor, and the familiarity of explant teams in donor hospitals was considered advantageous. Most donor hospitals do not expect to profit in terms of financial savings. When asked for further possible measures to improve organ donation, a clearer legal situation, but also the need for more information and education programs, including better media representation of transplant issues, were cited most frequently. An improvement in financial reimbursements for the donor hospitals as an instrument to enhance willingness for organ donation was not considered essential. In conclusion, our model of regionalization of organ procurement proved to be effective in achieving a high quality of organ retrieval and a reduction in personnel requirements for the transplant centers. In addition, the response from donor hospitals was unequivocally positive and may, thus, positively influence donor activity. Relevant financial savings can result from reduced on-call duties and minimized traveling costs. Further attempts to rationalize organ procurement could possibly include heart(-/lung)surgeons in the regionalized teams.

ENDOR studies of the primary donor cation radical in mutant reaction centers of Rhodobacter sphaeroides with altered hydrogen-bond interactions

The electronic structure of the cation radical of the primary electron donor was investigated in genetically modified reaction centers of Rhodobacter sphaeroides. The site-directed mutations were designed to add or remove hydrogen bonds between the conjugated carbonyl groups of the primary donor, a bacteriochlorophyll dimer, and histidine residues of the protein and were introduced at the symmetry-related sites L168 His-->Phe, HF(L168), and M197 Phe-->His, FH(M197), near the 2-acetyl groups of the dimer and at sites M160 Leu-->His, LH(M160), and L131 Leu-->His, LH(L131), in the vicinity of the 9-keto carbonyls of the dimer. The single mutants and a complete set of double mutants were studied using EPR, ENDOR, and TRIPLE resonance spectroscopy. The changes in the hydrogen bond situation of the primary donor were accompanied by changes in the dimer oxidation midpoint potential, ranging from 410 to 710 mV in the investigated mutants [Lin, X., Murchison, H. A., Nagarajan, V., Parson, W. W., Williams, J. C. & Allen, J. P. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 10265-10269]. It was found that the addition or removal of a hydrogen bond causes large shifts of the spin density between the two halves of the dimer. Measurements on double mutants showed that the unpaired electron can be gradually shifted from a localization on the L-half of the dimer to a localization on the M-half, depending on the hydrogen bond situation. As a control, the effects of the different hydrogen bonds on P.+ in the mutant HL(M202), which contains a BChlL-BPheM heterodimer as the primary donor with localized spin on the BChl aL [Bylina, E. J., & Youvan, D. C. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 7226-7230; Schenck, C. C., Gaul, D., Steffen M., Boxer S. G., McDowell L., Kirmaier C., & Holten D. (1990) in Reaction Centers of Photosynthetic Bacteria (Michel-Beyerle M. E., Ed.) pp 229-238, Springer, Berlin] were studied. In this mutant only small local changes of the spin densities (< or = 10%) in the vicinity of the hydrogen bonds were observed. The effects of the introduced hydrogen bonds on the spin density distribution of the dimer in the mutants are discussed in terms of different orbital energies of the two BChl a moieties which are directly influenced by hydrogen bond formation. The observed changes of the spin density distribution for the double mutants are additive with respect to the single mutations.(ABSTRACT TRUNCATED AT 400 WORDS)

Zygotic caudal regulation by hunchback and its role in abdominal segment formation of the Drosophila embryo

caudal (cad) is a maternally and zygotically expressed gene in Drosophila whereby the two phases of expression can functionally replace each other. The zygotic expression forms an abdominal and a posterior domain, whereby only the posterior domain has so far been studied with respect to its regulation and function. We show here that the abdominal cad domain is regulated by the hunchback (hb) gradient through repression at high concentrations and activation at low concentrations of HB protein. To study the function of the abdominal cad domain in the absence of redundant interactions, we have utilized an experimental system in which the embryo lacks the normal bicoid (bcd) and hb expression. An artificial hb gradient is then introduced into such embryos, which results in an induction of an ectopic zygotic cad domain in the more anterior region. Employing this system, we show that the cad domain functions by activating the expression of the abdominal gap genes knirps (kni) and giant (gt). We conclude that cad is the so far missing region-specific activator of abdominal segmentation genes.

Femorodistal vein grafts: the utility of graft surveillance criteria

PURPOSE

This retrospective review of femorodistal vein grafts was analyzed to determine the usefulness of various graft surveillance criteria.

METHOD

The surveillance schedule involved evaluations at 1 month, every 3 months the first year, and then every 6 months. Salvage intervention or graft occlusion occurring within the next follow-up interval defined surveillance end points. One hundred two grafts (329 surveillance visits) had an ankle/brachial index (ABI). A duplex scanning-determined midgraft peak systolic flow velocity (PSFV) was available for 81 grafts (262 visits). Forty-eight grafts (137 visits) had both a PSFV and entire graft duplex scanning (EGDS) to determine stenosis greater than 50%, whereas 40 grafts (91 visits) had simultaneous ABI and EGDS.

RESULTS

When a greater than 15% decrease in ABI denoted an abnormal surveillance study result, a positive predictive value (PPV) of 24.3% and negative predictive value of 94.5% were noted. Similarly, a PSFV cutoff of less than 35 cm/sec demonstrated values of 26.3% and 94.2%, respectively. When an EGDS of greater than 50% stenosis or a PSFV of less than 35 cm/sec were the cutoff criteria, the PPV was 36.7% and negative predictive value 99.1%, whereas characterizing abnormal results further with ABI (> 15% decreases) increased the PPV to 83.3%.

CONCLUSION

The combination of an EGDS, midgraft PSFV, and ABI provides optimal follow-up for our patients with a femorodistal vein graft.

Nitric oxide and prostaglandin systems inhibition on the isolated perfused human placenta from normal and preeclamptic pregnancies

Isolated human placental cotyledons from normal (NG) and preeclamptic gestants (PG) were perfused in vitro, and the effect of N omega-nitro-L-arginine (L-NA, 100 microM), methylene blue (MB, 50 microM), and indomethacin (INDO, 10 microM), on resting perfusion pressure and on the 5-hydroxytryptamine (5-HT)-induced vasoconstriction was established. In the HG, L-NA and MB increased resting perfusion pressure (p < 0.001) and INDO had no significant effect on resting pressure. In the PG, these agents did not significantly modify resting perfusion pressure. In the PG, 5-HT (10 microM-1 microM) caused greater maximal increases in perfusion pressure than in NG. In the NG, L-NA greatly enhanced the 5-HT-induced pressure, however INDO attenuated this effect. In the PG, L-NA did not modify significantly the 5-HT-induced response, but INDO reduced this response. These results suggest that basal release of nitric-oxide but not of vasodilator prostanoids may contribute to the low resting vascular tone in the NG and attenuates the strong vasoconstrictor effect induced by 5-HT. Impairment of action of nitric oxide could contribute to the enhanced pressor response to 5-HT observed in the PG.

Combined amyloidosis of the upper and lower respiratory tract

Pulmonary and laryngeal manifestations of localized and organ-limited amyloidosis are sometimes seen, although pulmonary and laryngeotracheal amyloidosis are not always associated. Diagnosis can only be established histologically by the characteristic green birefringence in polarized light after Congo red staining and by immunohistochemical techniques. We describe the case of a 77-year-old woman who presented with hoarseness and an unproductive cough due to extensive amyloid deposits in both the upper and lower respiratory tract, immunohistochemically proven as the A lambda-type.