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Biomedical subjects

B Voigt

Publications and source records attributed to B Voigt.

80 records · Page 5Linked to original sources
PubMedDate not supplied

[Cerebral perfusion in newborn infants treated with high-frequency oscillation ventilation].

UNLABELLED: The effects of high-frequency oscillatory ventilation (HFOV) on hemodynamic parameters have been shown in animal as well as in clinical studies. In a further study we could demonstrate, that after change of a conventional positive pressure ventilation (CMV) to HFOV flow velocities in cerebral arteries decreased. In the following we added to the dopplerflow method the continuous examination of cerebral oxygenation with near infrared spectroscopy (NIRS). PATIENTS: 19 measurements were prospectively conducted in 18 neonates. The infants were mechanically ventilated with HFOV and were in a stable condition. METHODS: Before change from HFOV to CMV doppler signals of the anterior cerebral artery were measured. We repeated this at the end of the study in each patient. NIRS-optodes were placed on the front and the os parietale of each infant. After stabilization of the system we changed from HFOV to CMV without disconnection of the patient from the machine. PCO2 was registered continuously via a transcutaneous probe, as well as oxygen saturation via pulse oxymetry. Statistical analysis was performed with Wilcoxon test. RESULTS: There were no significant changes of doppler-signals during the study (median vs. 25 cm/s (+/- 6) during HFOV, 28 cm/s (+/-/) during CMV). The parameter of NIRS, oxygenated hemoglobin HbO [-1.5 U (+/- 22.78)] at 15 minutes after change), reduced hemoglobin HbR [-1.17 U (+/- 5.26)] and total hemoglobin HbT [-2.68 U (+/- 18.7)] remained stable during the change from HFOV to CMV, too. In five infants there was a decrease and in two an increase of HbO 15 minutes after change, which correlated with decrease or increase of pCO2. CONCLUSION: In a combined measurement of dopplerflow and NIRS we found no special effect of HFOV on cerebral hemodynamics comparing with CMV. Changes of cerebral oxygenation in NIRS correlated with pCO2.

Anterior Cerebral Artery↗
PubMedDate not supplied

Capillary microscopy of the nailfold in healthy subjects.

In a total of 100 healthy subjects (36 males, 64 females) aged between 5 and 58 years, capillary microscopy of the nailfold was performed in all the fingers of both hands. The aim of this study was to determine whether capillary abnormalities, hitherto regarded as pathological, were to be found, and if so, to establish their frequency and nature. Capillary branchings - on average 4-5/person - were seen in 78% of the subjects investigated, and proved to be most common in digits IV and V of both hands. Of the subjects investigated, 94% showed meandering, 64% tortuous loops, 25% hemorrhagic extravasations, and 19% apical dilatations of the capillaries. Only a single case of a giant loop was seen. Neither avascular fields, stasis nor reversion of blood flow were seen. Maricq's venule index was increased in 3 subjects. These findings clearly indicate that the significance of deviating capillary patterns need to be reconsidered, for branchings or hemorrhagic extravasations can certainly be found in healthy subjects.

Adolescent↗
PubMedDate not supplied

Patient participation in deciding breast cancer treatment and subsequent quality of life.

This investigation of patients with early breast cancer examined relationships among patient involvement in deciding treatment (i.e., whether to undergo breast removal or breast conservation), perceptions of control over treatment decisions, and subsequent health-related quality of life. It was predicted 1) that patients who more actively participated in consultations to decide treatment would perceive more decision control than would more passive patients and 2) that patients who perceived greater decision control would report better health-related quality of life following treatment than would patients perceiving less decision control. Sixty patients with stage I or II breast cancer allowed their consultations with surgeons to be audiorecorded. Following these visits, patients reported on their involvement in the consultation, optimism for the future, knowledge about treatment, and two aspects of perceived decision control, the perception of having a choice for treatment and the extent to which the doctor or patient was responsible for the decision. Six and 12 months postoperatively, 51 patients (85%) returned a follow-up survey assessing perceived decision control and health-related quality of life. The first prediction received some support. The patients who had more actively participated in their consultations, particularly in terms of offering opinions, assumed more responsibility for treatment decisions during the year following surgery than did less expressive patients. Also, the patients who reported more involvement in their consultations later believed they had had more of a choice for treatment. The second hypothesis was partially supported. Six and 12 months following treatment, the patients who believed they were more responsible for treatment decisions and believed they had more choice of treatment reported higher levels of quality of life than did the patients who perceived themselves to have less decision control. However, perceived control at the time of treatment did not predict later quality of life. Theoretical and clinical implications are discussed.

Adult↗
PubMedDate not supplied

Metabolic transformation of the brassinosteroid 24-epi-castasterone by the cockroach Periplaneta americana.

After feeding of 24-epi-castasterone to the cockroach Periplaneta americana an organ-specific epimerization of the brassinosteroid to 2,24-diepi-castasterone could be detected in female insects. The metabolite being observed only in the ovaries and not in the testes of the insect was identified by GC/MS in comparison with a synthesized authentic sample. Contrary, 24-epi-brassinolide is not metabolized in the sexual organs of Periplaneta americana. This is the first evidence of a metabolic transformation of a brassinosteroid in insects.

Animals↗
PubMedDate not supplied

[Two-photon excitation fluorescence spectrum of the light-harvesting complex LH2 from Chromatium minutissimum within 650-745 nm range is determined by two-photon absorption of bacteriochlorophyll rather than of carotenoids].

Two-photon fluorescence excitation spectra of the peripheral light-harvesting complex LH2 from the purple photosynthetic bacterium Chromatium minutissimum were examined within the expected spectral range of the optically forbidden S1 singlet state of carotenoids. LH2 preparations isolated from wild-type and carotenoid-depleted cells were used. 100-fs laser pulses in the range of 1300-1490 nm with an energy of 7-9 mW (corresponding to one-photon absorption between 650 and 745 nm) were used for two-photon fluorescence excitation. It was shown that two-photon fluorescence excitation spectra of LH2 complex from wild and carotenoid-depleted cells are very similar to each other and to the two-photon fluorescence excitation spectrum of bacteriochlorophyll a in acetone. It was concluded that direct two-photon excitation of bacteriochlorophyll a determines the fluorescence of both samples within the 650-745 nm spectral range.

Bacteriochlorophylls↗
PubMedDate not supplied

Time dependent changes induced by external perturbations on a low molecular weight RNA.

The behaviour of a soluble RNA (MW 19,000) extracted from calf thymus was studied in a partially aqueous solvent. A mixture of dioxane and an aqueous solution of 50 mM NaCl (10:1) was used to dissolve the RNA and the slow optical changes of the solution depending on time and RNA concentration were followed. The relaxation of the RNA was measured after a T-jump in the dioxane-NaCl solvent with an addition of 7 mM methyl red at 470 nm. The relaxation time was measured after experiments carried out with different RNA concentration and the rate process appears to be independent of the RNA concentration.

Dioxanes↗