Magnetic and electrical stimulation of undulating nerve fibres: a simulation study

Mathematical models of myelinated nerve fibres are highly stylized abstractions of real nerve fibres. For example, nerve fibres are usually assumed to be perfectly straight. Such idealizations can cause discrepancies between theoretical predictions and experimental results. One well-known discrepancy is that the currently used models predict (contradictory to experimental findings) that an activation of nerve fibres is not possible with a pure transverse electric field. This situation occurs when a magnetic coil is placed symmetrically above a straight nerve fibre for magnetic nerve stimulation, or when an anode and a cathode are placed equidistantly on a line perpendicular to the fibre in the case of electrical stimulation. It is shown that this discrepancy does not occur if the physiological undulation of peripheral nerve fibres is included in the models. Even for small undulation amplitudes (e.g. 0.02 mm), it is possible to activate the fibre in these positions. For physiological undulations, as found in the literature, and favourable (off-centre) positions, the typical reduction of the thresholds is in a range between one and five, compared with perfectly straight fibres.     

Congenital pulmonary atresia with ventricular septal defect: angiographic and surgical correlates

Of 181 patients with severe congenital pulmonary atresia and ventricular septal defect or "type IV truncus" (an obsolete term), all but 11% had true central pulmonary arteries. These arteries were demonstrable by large serial biplane angiograms using multiple selective injections into collateral vessels, frequent photographic subtraction, and occasional pulmonary vein-wedge angiograms. These techniques are extremely important for accurate diagnosis and in planning corrective or palliative surgery, which was done in 77% of patients with pulmonary arteries.     

Patterns of structural deterioration due to ischemia in Purkinje fibres and different layers of the working myocardium

Cellular and mitochondrial swelling are regarded as typical intra-ischemic alterations ("IIA"), contraction band lesions (CBL), in contrast, as products of post-ischemic reperfusion. The occurrence of both types of structural deterioration was investigated in Purkinje fibres and subendocardial and intramural working myocardium: initially after St. Thomas- or HTK cardioplegia, then during ensuing global ischemia up to the "practical limit of resuscitability", and following post-ischemic reperfusion. Generally, Purkinje fibres are not better preserved than neighbouring working myocardium. Comparing St. Thomas- and HTK cardioplegia, considerable quantitative, but not qualitative differences in the reaction patterns of different cell types or layers arise. Immediately after cardioplegia, CBL are completely lacking in both cell types. During ischemia, CBL occur occasionally in Purkinje fibres and seldom in subendocardial working myocardium, "IIA" predominate. During post-ischemic reperfusion "IIA" tend to reverse in all layers, whereas CBL are found to remain in the subendocardial cell types. In intramural layers, CBL occur only during reperfusion. Thus, we deduce that cardioplegia only modulates the severity of "IIA" and the frequency of CBL, but cannot abolish the particular sensitivity of subendocardial Purkinje fibres to global ischemia. Prerequisites for the development of irreversible CBL are on the one hand ischemic metabolic alterations and corresponding energy deficits, and, on the other hand, a supply of oxygen. The oxygen may be inadequately supplied via diffusion during ischemia or may be subsequently provided by reperfusion.     

Infants born to narcotic dependent mothers: Physical growth patterns in the first 12 months of life

Objectives: To describe the physical growth patterns of infants born to narcotic dependent mothers (INDM) over a 12 months period and, if possible, to relate the growth to drug taking patterns during pregnancy.
Methodology: The growth of a cohort of 43 INDM was measured during the first 12 months of life. Weight and length measurements were compared with percentile charts and converted to Z scores. Questionnaire data about drug taking practices, demographic variables and the neonatal period (including withdrawal scores) were obtained.
Results: Twenty-four (55.8%) of INDM had evidence of neonatal drug withdrawal requiring treatment with phenobarbitone. At birth, Z scores for weight and length indicated relative intrauterine growth retardation. By 12 months, there had been some catch up growth, but Z scores for weight and length were still below zero. Persistent weight retardation at 12 months was correlated with methadone dosage during pregnancy, but not the need for phenobarbitone therapy.
Conclusions: The growth patterns of INDM in the first 12 months of life indicated that at birth there was evidence of intrauterine growth retardation, but by 12 months the growth was little different from the rest of the community. There appears to be some influence of narcotic agents taken while pregnant on subsequent growth of INDM.     

Rising incidence of type 1 diabetes in Scottish children, 1984-93. The Scottish Study Group for the Care of Young Diabetics

OBJECTIVES: To calculate the incidence of type 1 diabetes in Scottish children aged less than 15 years between 1984 and 1993; to examine changes in incidence; and to calculate the prevalence of diabetes at the end of this period. DESIGN: Three data sources were used to construct the Scottish Study Group for the Care of Young Diabetics register: active reporting of all new cases; reports from the Scottish Morbidity Register 1; and local registers. SUBJECTS: All children resident in Scotland diagnosed with primary insulin dependent diabetes mellitus when less than 15 years of age between 1984 and 1993. MAIN OUTCOME MEASURES: Annual incidence and prevalence rate for Scotland; time trend in incidence over the 10 years; differences in incidence between the three different age groups; and completeness of the register. RESULTS: The average annual incidence for Scotland was 23.9/100,000 children. The prevalence rate was 1.5/1000 in 1993. A total of 2326 cases was identified from the three sources. Capture-recapture analysis suggests a case ascertainment of 98.6%. The annual incidence rates increased at a rate of 2% each year (rate ratio = 1.02, 95% confidence interval (CI) 1.01 to 1.03). The incidence was higher in boys than girls (rate ratio = 1.08, 95% CI 1.00 to 1.18), and the incidence rates increased with age: 15.3/100,000/year for age 0-4 years, 24.4/ 100,000/year for age 5-9 years, and 31.9/ 100,000/year for age 10-14 years. CONCLUSIONS: The incidence of type 1 diabetes in Scotland is increasing and the prevalence is relatively high. These findings have important implications for health service resource allocation. The Scottish Study Group for the Care of Young Diabetics' register provides a base for monitoring and research.     

Aktualisierte Handlungsempfehlung nach der S1-Leitlinie „Vitamin-D-Mangel-Rachitis“

Monatsschrift Kinderheilkunde -     

Pharmacokinetic profile of nomegestrol acetate and 17β-estradiol after multiple and single dosing in healthy women

BackgroundThe pharmacokinetics of the monophasic oral contraceptive nomegestrol acetate (NOMAC) plus 17β-estradiol (E₂) were investigated after a single dose and multiple dosing.Study designNOMAC/E₂ (2.5 mg/1.5 mg) was administered daily to healthy women (18–50 years, n= 23) for 24 days; blood samples for pharmacokinetic analysis were obtained on Day 24 and again, after a 10-day pill-free interval, on Day 35 after a single dose.ResultsNOMAC reached steady state after 5 days with mean ± standard deviation (SD) trough NOMAC concentration (C_av) of 4.4±1.4 ng/mL. On Day 24, mean±SD peak NOMAC concentration (C_max, 12.3±3.5 ng/mL) was reached in mean 1.5 h (t_max); the mean±SD elimination half-life (t_½) was 45.9±15.3 h. After a single dose, NOMAC mean±SD C_max was 7.2±2.0 ng/mL and mean±SD t_½ was 41.9±16.2 h. On Day 24, E₂ mean±SD C_av was 50.3±25.7 pg/mL; mean±SD C_max was 86.0±51.3 pg/mL. After a single dose, mean±SD E₂ C_max was 253±179 pg/mL.ConclusionsThese data demonstrate that NOMAC/E₂ has a pharmacokinetic profile consistent with once-daily dosing.     

Risikostratifizierung und Therapie kardialer Amyloidosen

Cardiac amyloidoses are a heterogeneous group of cardiomyopathies that are resistant to treatment and are associated with a poor outcome. Standard heart failure treatment is usually not well tolerated and the underlying disease remains unaffected. The clinical picture is uncharacteristic. Cardiac amyloidosis is often associated with dysfunction of additional organs. Early cardiac amyloid involvement usually reveals left ventricular hypertrophy, impairment of longitudinal shortening and diastolic ventricular function. Without adequate therapy (bi-)ventricular hypertrophy will progress to severe systolic ventricular function decrease. The combination of low voltage pattern, left ventricular hypertrophy and granular sparkling is characteristic for advanced cardiac amyloid involvement. Cardiac magnetic resonance imaging and scintigraphy yield further information on the pattern and severity of cardiac involvement. In unclear cases (left ventricular) endomyocardial biopsy is necessary. Detection of early cardiac involvement and proper identification of patients at high risk for sudden cardiac death due to rapid progressive amyloidosis is still incompletely defined. Referral to specialized centers is strongly recommended.