Biomedical subjects
Publications and source records attributed to M Erdmann.
Post-traumatic hyperextension deformity of the thumb due to rupture of volar plate is a rare but clinically important phenomenon. These injuries are usually related to ball sports like basketball and handball. However, we describe an unusual association in an elderly patient with chronic use of an electronic game, which merits a high index of suspicion for early diagnosis and treatment to prevent long-term complications.
We study the quantum dynamics in a model system consisting of two electrons and a nucleus which move between two fixed ions in one dimension. The numerically determined wave functions allow for the calculation of time-dependent electron localization functions in the case of parallel spin and of the time-dependent antiparallel spin electron localization functions for antiparallel spin. With the help of these functions, it becomes possible to illustrate how electronic localization is modified through the vibrational wave-packet motion of the nucleus.
We investigate the correlated electronic and nuclear motion in a model system as proposed by Shin and Metiu [J. Chem. Phys. 102, 9285 (1995)]. The quantum dynamics is studied during laser induced electronic transitions. Here, the influence of nonadiabatic coupling on the absorption spectrum is investigated and the Franck-Condon principle is illustrated in terms of the temporal changes of electronic and nuclear densities. In the case of intense field excitation, multiphoton processes become important, and electronic as well as vibrational wave packets are prepared.
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Peripartum cardiomyopathy is a rare disorder with an incidence from 1:3,000 to 1:15,000 live births and thus not often described in the anaesthesiology literature. The etiology of this disease is still not known but the symptoms are similar to idiopathic dilated cardiomyopathy. Echocardiographic findings show a dilatation of the left ventricle in addition to abnormal wall motion with a severe reduction of the cardiac function. Despite the rarity of this disorder, the anaesthesiologist or ICU physician should consider peripartal cardiomyopathy as a differential diagnosis to ensure an adequate perioperative management. There seems to be an increased incidence in pregnant women who are elderly (age >30 years),who have a history of gestosis/hypertension,have a gemini pregnancy or are of black origin. The prognosis depends on the recovery of the left ventricular contractility within the first 6 months after onset of the disease. The mortality rate is reported to vary between 25% and 50%. Heart transplantation is regarded as the last resort which has successfully been performed with several patients. This case describes the perioperative management of a 32-year-old women with peripartum cardiomyopathy.
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We report the first measurements of z-dependent coherent optical transition radiation (COTR) due to electron-beam microbunching at high gains ( >10(4)) including saturation of a self-amplified spontaneous emission free-electron laser (FEL). In these experiments the fundamental wavelength was near 530 nm, and the COTR spectra exhibit the transition from simple spectra to complex spectra ( 5% spectral width) after saturation. The COTR intensity growth and angular distribution data are reported as well as the evidence for transverse spectral dependencies and an "effective" core of the beam being involved in microbunching.
Self-amplified spontaneous emission in a free-electron laser has been proposed for the generation of very high brightness coherent x-rays. This process involves passing a high-energy, high-charge, short-pulse, low-energy-spread, and low-emittance electron beam through the periodic magnetic field of a long series of high-quality undulator magnets. The radiation produced grows exponentially in intensity until it reaches a saturation point. We report on the demonstration of self-amplified spontaneous emission gain, exponential growth, and saturation at visible (530 nanometers) and ultraviolet (385 nanometers) wavelengths. Good agreement between theory and simulation indicates that scaling to much shorter wavelengths may be possible. These results confirm the physics behind the self-amplified spontaneous emission process and forward the development of an operational x-ray free-electron laser.
Coral reef degradation resulting from nutrient enrichment of coastal waters is of increasing global concern. Although effects of nutrients on coral reef organisms have been demonstrated in the laboratory, there is little direct evidence of nutrient effects on coral reef biota in situ. The ENCORE experiment investigated responses of coral reef organisms and processes to controlled additions of dissolved inorganic nitrogen (N) and/or phosphorus (P) on an offshore reef (One Tree Island) at the southern end of the Great Barrier Reef, Australia. A multi-disciplinary team assessed a variety of factors focusing on nutrient dynamics and biotic responses. A controlled and replicated experiment was conducted over two years using twelve small patch reefs ponded at low tide by a coral rim. Treatments included three control reefs (no nutrient addition) and three + N reefs (NH4Cl added), three + P reefs (KH2PO4 added), and three + N + P reefs. Nutrients were added as pulses at each low tide (ca twice per day) by remotely operated units. There were two phases of nutrient additions. During the initial, low-loading phase of the experiment nutrient pulses (mean dose = 11.5 microM NH4+; 2.3 microM PO4(-3)) rapidly declined, reaching near-background levels (mean = 0.9 microM NH4+; 0.5 microM PO4(-3)) within 2-3 h. A variety of biotic processes, assessed over a year during this initial nutrient loading phase, were not significantly affected, with the exception of coral reproduction, which was affected in all nutrient treatments. In Acropora longicyathus and A. aspera, fewer successfully developed embryos were formed, and in A. longicyathus fertilization rates and lipid levels decreased. In the second, high-loading, phase of ENCORE an increased nutrient dosage (mean dose = 36.2 microM NH4+; 5.1 microM PO4(-3)) declining to means of 11.3 microM NH4+ and 2.4 microM PO4(-3) at the end of low tide) was used for a further year, and a variety of significant biotic responses occurred. Encrusting algae incorporated virtually none of the added nutrients. Organisms containing endosymbiotic zooxanthellae (corals and giant clams) assimilated dissolved nutrients rapidly and were responsive to added nutrients. Coral mortality, not detected during the initial low-loading phase, became evident with increased nutrient dosage, particularly in Pocillopora damicornis. Nitrogen additions stunted coral growth, and phosphorus additions had a variable effect. Coral calcification rate and linear extension increased in the presence of added phosphorus but skeletal density was reduced, making corals more susceptible to breakage. Settlement of all coral larvae was reduced in nitrogen treatments, yet settlement of larvae from brooded species was enhanced in phosphorus treatments. Recruitment of stomatopods, benthic crustaceans living in coral rubble, was reduced in nitrogen and nitrogen plus phosphorus treatments. Grazing rates and reproductive effort of various fish species were not affected by the nutrient treatments. Microbial nitrogen transformations in sediments were responsive to nutrient loading with nitrogen fixation significantly increased in phosphorus treatments and denitrification increased in all treatments to which nitrogen had been added. Rates of bioerosion and grazing showed no significant effects of added nutrients. ENCORE has shown that reef organisms and processes investigated in situ were impacted by elevated nutrients. Impacts were dependent on dose level, whether nitrogen and/or phosphorus were elevated and were often species-specific. The impacts were generally sub-lethal and subtle and the treated reefs at the end of the experiment were visually similar to control reefs. Rapid nutrient uptake indicates that nutrient concentrations alone are not adequate to assess nutrient condition of reefs. Sensitive and quantifiable biological indicators need to be developed for coral reef ecosystems. The potential bioindicators identified in ENCORE should be tested in future research on coral reef/nutrient interactions. Synergistic and cumulative effects of elevated nutrients and other environmental parameters, comparative studies of intact vs. disturbed reefs, offshore vs. inshore reefs, or the ability of a nutrient-stressed reef to respond to natural disturbances require elucidation. An expanded understanding of coral reef responses to anthropogenic impacts is necessary, particularly regarding the subtle, sub-lethal effects detected in the ENCORE studies.
The staining of skin by silver is termed argyria and is grey-blue in colour. This may be caused by a number of mechanisms such as ingestion and direct implantation. We report an unusual case, caused by an impacted earring, where the skin discoloration was not entirely typical of argyria. This may have been due to copper impurities present in the earring. The literature on the subject is also reviewed.
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OBJECTIVE: This study was conducted to evaluate uteroplacental and fetal hemodynamics in fetuses exposed to low-dose aspirin (100 mg/d). DESIGN: Randomized, placebo-controlled, double-blind trial. SUBJECTS: The study protocol included singleton pregnancies of less than 20 gestational weeks at risk for pre-eclampsia or fetal growth restriction. Exclusion criteria were diabetes mellitus, pre-existing proteinuric hypertension or fetal malformations. Forty-three pregnant women were randomly allocated to daily treatment with 100 mg aspirin (n = 22) or placebo (n = 21). METHODS: Pulsed Doppler measurements of the uterine artery, fetal middle cerebral artery, fetal aorta, ductus arteriosus and atrioventricular valves were performed longitudinally at 14 day intervals starting from 18 gestational weeks until delivery. Results were expressed as group medians (aspirin vs. placebo) and were analyzed by Mann-Whitney U-test. RESULTS: There was no difference in uterine, umbilical, aortic, middle cerebral and ductus arteriosus blood flow between the aspirin group and controls. Median ductal peak flow velocities increased with gestational age in both groups, but differences between groups did not reach significance. In the third trimester of pregnancy, ductal peak velocities > 140 cm/s were occasionally observed in both groups. However, end diastolic velocities > 35 cm/s or atrioventricular valve regurgitation never occurred. CONCLUSIONS: Daily administration of low-dose aspirin during the second and third trimesters of pregnancy does not alter uteroplacental or fetoplacental hemodynamics and does not cause moderate or severe constriction of the ductus arteriosus.
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Triamcinolone acetonide (TCA) is a corticosteroid that is frequently used in the treatment of asthma. After inhalation, TCA can become systemically available when the inhaled formulation is swallowed, causing undesirable systemic effects. A clinical study was conducted to determine the systemic side effects of TCA after intravenous (2 mg as phosphate ester), oral (5 mg), and inhaled (2 mg) administration. Blood samples were collected at appropriate times over 24 hours, and TCA concentrations in plasma were measured by high-performance liquid chromatography and radioimmunoassay. Free drug concentrations were determined by ultrafiltration for correlating pharmacokinetics and pharmacodynamics. The free fraction of TCA (+/- standard deviation) was 29.0 +/- 1.3% and was independent of the investigated concentration range up to 1,000 ng/mL. Pharmacodynamic parameters were determined by monitoring lymphocytes, granulocytes, and cortisol. Pharmacokinetic/pharmacodynamic modeling was performed using a modified Emax model for lymphocytes and granulocytes. A novel linear release rate model was used to characterize the cortisol data. The E50 values determined from all three pharmacodynamic endpoints were not significantly different for the three treatments, indicating that these effects can be explained based on systemic steroid concentrations.
The pharmacokinetics of triamcinolone acetonide were studied after intravenous (2 mg), oral (5 mg), and inhaled (2 mg) administration. Triamcinolone acetonide concentrations were measured in plasma by high-performance liquid chromatography/radioimmunoassay. After intravenous administration, triamcinolone acetonide was eliminated with a total body clearance of 37 L/h and a half-life of 2.0 hours. The volume of distribution was 103 L, and oral bioavailability averaged 23%. Absorption was rapid, achieving maximum triamcinolone acetonide levels of 10.5 ng/mL after 1 hour. After inhalation, bioavailability averaged 22% with maximum levels of 2.0 ng/mL observed after 2.1 hours. The resulting systemic levels for all three treatments caused a significant decrease in the number of lymphocytes in blood.