Capillary batch injection analysis (CBIA) is applied to the determination of ascorbic acid in nanolitre samples at neutral pH. It is demonstrated that pulsed amperometric detection is superior to constant-potential amperometric detection with respect to signal stability. The calibration plot is linear within the studied concentration range between 0.5 mM and 5 mM and the reproducibility is characterized by a relative standard deviation of 0.80% for 10 successive injections of 188 nL of 3.5 mM ascorbic acid. The attainable sample throughput is up to 500 per hour.

Ascorbic Acid↗

PubMedDate not supplied

Dissection of an aneurysmic ascending aorta in a child with atresia of the aortic isthmus.

A boy with atresia of the aortic isthmus suffered dissection of the aneurysmatic ascending aorta. It is assumed that he had coarctation as a newborn and survived the subsequently developed atresia because of extensive collateralization.

Adolescent↗

PubMedDate not supplied

Biosynthesis of frog skin mucins: cysteine-rich shuffled modules, polydispersities and genetic polymorphism.

1. Frog integumentary mucins (FIM-A.1, FIM-B.1 and FIM-C.1) consist of typical threonine-rich highly O-glycosylated (semi)repetitive domains, and cysteine-rich modules, i.e. the P-domain, the short consensus repeat and a region with high similarity to the C-terminal end of von Willebrand factor (designated here CC29-motif). 2. These modules are thought to be involved in protein-protein interactions and they have been observed in a variety of extracellular proteins. In FIMs, these modules may be involved in oligomerization processes leading to an entangled mucin network. 3. Polydispersities have been detected in FIM-B.1 and FIM-C.1 within single individuals. Multiple transcripts are probably generated by alternative splicing of a huge array of different (semi)repetitive cassettes encoding the threonine-rich domains. 4. Furthermore, genetic polymorphism is observed between different individuals, probably due to allelic variations in the number of (semi)repetitive cassettes.

Alleles↗

PubMedDate not supplied

How radiation-specific is the dicentric assay?

QUESTION: Quantitative cytogenetic analysis of structural chromosome aberrations in human peripheral blood lymphocytes is widely used as an assay to detect and quantify exposure to a variety of clastogens. Unstable chromosome rearrangements, dicentric chromosomes (dic) and centric ring chromosomes (centric r), are routinely used as biomarkers to assess human exposure to ionizing radiation ("biological dosimetry"). In the moderate- to high-dose range many authors consider the dic assay sufficiently radiation-specific for both practical and legal purposes. However, specificity has never been evaluated in quantitative terms. The high sensitivity of the assay would in principle allow for applications in the range of low-dose exposure which has been a major concern in epidemiologic studies. Validity of the assay then critically depends on specificity. METHODS: A mathematical model is proposed which includes as parameters the decline of dicentric aberrations in vivo, the linear dose coefficient for the induction of dic and the average total radiation exposure of the population. To assess radiation-specificity of the dic assay the equilibrium dicentric rate due to radiation is compared to measurements of the background rate of dic in unexposed controls. RESULTS: Environmental and medical radiation combined account for at least about 80% of the average background level of dicentrics. CONCLUSION: It is concluded that the dicentric assay is highly specific for ionizing radiation and can therefore be used to assess prior exposure in the dose range of interest in environmental epidemiology.

Adult↗

PubMedDate not supplied

[The problem of response in epidemiologic studies in Germany (Part II)].

The first part of this paper introduced various definitions of response and discussed their significance in the context of different study types. This second part addresses incentives as a method to increase response and evaluates the impact of non response or delayed response on the validity of the study results. Recruitment aims at minimising the proportion of refusal. To achieve this, incentives can be used and potential participants can be contacted in a sequence of increasing intensity. The effectiveness of different incentives was investigated within the pretest of the German survey on children and adolescents by the Robert Koch Institute. A low response is often interpreted in terms of non-response bias. This assumption, however, is as incorrect as would be opposite conclusion, that a high response guarantees valid results. Any study of the influence of nonresponse requires information on non-responders. The comparison between early and late responders as an indirect method to evaluate systematic differences between participants and non-participants by wave analysis is demonstrated within the Northern Germany Leukaemia and Lymphoma study (NLL). The German guidelines for Good Epidemiologic Practice recommend to solicit a minimum of information on the principal hypotheses of a study from non-participants. The example of a population-based health survey (Cooperative Health Research in the Region of Augsburg, KORA) illustrates how information on non-responders within a quantitative non-responder analysis can be achieved and used for the estimation of prevalences. Recommendations how to deal with the response in epidemiological studies in Germany are suggested.

Adolescent↗

PubMedDate not supplied

[Mediastinal cystic lymphangioma as a cause of hydrops fetalis].

This report is upon a case with fetal hydrops on the base of a paracardiac cystic lymphangioma in the mediastinum. The newborn which had hypoplastic lungs and multiple pneumatothoraces died because of a pulmonary insufficiency. An overview is given about the most common causes of the nonimmune fetal hydrops, and the pathomechanisms are discussed.

Female↗

PubMedDate not supplied

[Experiences with ambulatory long-term blood pressure measurement in childhood and adolescence].

In a period of more than 2 years experiences with ambulatory blood pressure monitoring (ABPM) in children and adolescents aged from 2 years onward were collected, and practicability and clinical possibilities of diagnostic use were examined. We used the Medilog-ABP apparatus (Oxford Medical, Oxford Instruments Group P.L.C.), which functions fully automatically by the auscultatory method. The following results can be stated: 1. ABPM is accepted very well by young patients. Disturbances of normal behavior or sleep occurred in only 10% of the cases. 2. The rate of fault values in ambulatory long-term use is about 30%, by which useful diagnostic information is guaranteed. 3. By invasive and non-invasive parallel measurements a good validity of the values could be proved. 4. The amount of information provided by this method must be considered very great in clinical questions. ABPM allows a detailed evaluation of circadian blood pressure patterns, and an individual adjustment of circulation therapies. According to our experiences ambulatory blood pressure monitoring thus represents an enrichment of circulation diagnostics in pediatrics.

Adolescent↗

PubMedDate not supplied

[Modification of cardiovascular dynamics in orthostatic dysregulation in childhood by oxilofrin].

In 10 children with clinically and hemodynamically proven orthostatic dysregulation of the sympathetic type, non invasive hemodynamics using sphygmographic techniques as well as systolic time intervals were evaluated. Measurements were taken during 10 minutes in the supine and a 65 degrees position on a tilting table before and after acute administration of Oxilofrin, 20 mg as well as after 2 and 4 weeks of chronic treatment with 20 mg t.i.d. During orthostatic stress, Oxilofrin caused a significant increase in pulse pressure, cardiac output, stroke volume, and systolic ejection rate with a reduction in peripheral vascular resistance compared to control. Pre-ejection period and isovolumic contraction time, while prolonged on baseline orthostatic stress, were only slightly shortened by Oxilofrin. These hemodynamic actions of the drug are explained by a stimulation of adrenergic beta and alpha receptions with the consequence of decreasing venous capacitance and increased venous return, thus providing a useful hemodynamic profile for the treatment of orthostatic dysfunction.

Adolescent↗

PubMedDate not supplied

[Cardiac dysfunction in children with thalassemia major].

Evaluation of the cardiac function of seven patients with beta-thalassemia major was performed by continuous electrocardiography recording during a 24 hr period and during a short term exercise program. A reduction in left ventricular function was assessed by echocardiography and radiocardiography during resting and during exercise. Serious arrhythmias of various forms in the oldest patients (17 and 20 years) were observed during these tests. The younger patients were asymptomatic and their cardiac function tests showed no abnormality. In order to prevent transfusion related cardiac iron toxicity it would seem mandatory to motivate patients for better compliance while on chelation therapy.

Adolescent↗

PubMedDate not supplied

[Compression syndrome of the upper thoracic outlet (thoracic outlet syndrome)--report on a 13-year-old girl].

The thoracic-outlet-syndrome, a symptom complex consisting of arterial, venous and neural disorders of the upper extremity, is caused by compression of the neurovascular structures between the clavicle and the first rib. Other reasons are congenital abnormalities like a cervical rib, an abnormal first rib, acquired anatomic lesions like fractures and traumata or functional factors. The younger-and middle-age groups are most commonly involved. The symptoms are depending upon the point at which compression occurs and include pain, paresthesias, numbness, fatigue, pallor, coolness or swelling and enlargement of the arms. At physical examination a systolic murmur is heard in the supraclavicular region in 30 percent and the pulse of the upper extremity often is reduced. Diagnostic measurements include roentgenogram of the chest and the cervical spine, pulsed doppler-ultrasonography, nerve conduction-velocity testing and an arterio-venography. Treatment is nonoperative in patients with mild symptoms (shoulder-girdle-exercises) and operative in patients with severe or persistent symptoms. The operative treatment of choice is resection of the first rib by an axillary route. Risks are minimal, and the results are good to excellent in 90% of the cases. Because the thoracic outlet syndrome is very rare in childhood, we report a 13 year old girl which has undergone bilateral operation with excellent result.

Adolescent↗