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C Wolff

Publications and source records attributed to C Wolff.

173 records · Page 10Linked to original sources
PubMedDate not supplied

Vaginal Ureaplasma urealyticum colonization: influence on pregnancy outcome and neonatal morbidity.

The effects of Ureaplasma urealyticum colonization on pregnancy and neonatal outcome was prospectively studied in women with impending term or preterm delivery. One hundred and seventy women colonized with U. urealyticum as the only pathogenic microorganism and 83 women with negative cultures were enrolled for study. Compared to the controls, U. urealyticum colonization was associated with a significantly increased rate of amnionitis (2% vs 35%; p < 0.001), chorioamnionitis (0% vs 10%; p < 0.05), premature rupture of membranes (12% vs 35%; p < 0.001) and preterm delivery (10% vs 41%; p < 0.001). The rate of vertical transmission ranged from 38% in term infants to 95% in very low birth weight infants. U. urealyticum colonization at birth was associated with an increased risk for the development of respiratory distress syndrome (9% vs 51%), intraventricular hemorrhage (1% vs 7%) and bronchopulmonary dysplasia (4% vs 17%) in very low birth weight infants (< 1500 g). It is concluded that maternal U. urealyticum colonization is associated with amnionitis, chorioamnionitis and preterm delivery, and that tracheal colonization with U. urealyticum increases the risk for respiratory and neurological complications in very low birth weight infants.

Adult↗
PubMedDate not supplied

Diagnosis and treatment of the acute porphyrias: an interdisciplinary challenge.

The porphyrias comprise a group of fascinating disorders resulting from predominantly inherited as well as acquired deficiencies of one of the eight enzymes along the pathway of heme biosynthesis. On the basis of clinical aspects, the different types of porphyrias can be classified in acute and non-acute forms. However, an exact classification is often difficult since the porphyrias might reveal unspecific clinical symptoms and/or overlapping biochemical features. In particular, this is true for the acute porphyrias which can present with life-threatening acute neurovisceral attacks that require immediate medical intervention. Due to the multiple facets of these disorders, the diagnosis and treatment of the acute porphyrias should always imply a close interdisciplinary collaboration to serve patients and their families most effectively.

Acute Disease↗
PubMedDate not supplied

A method for increasing confidence in respiratory gas exchange measurements in mechanically ventilated patients.

Measurement of O2 uptake (VO2) and CO2 output (VCO2) with automated instruments can be used to optimize nutritional management of critically ill patients. However, these measurements may be made infrequently because of calibration problems or suspected inaccuracies, especially when the patient is given supplemental oxygen. A simple method is described for periodic testing of automated gas exchange measurements. While a test lung is mechanically ventilated an accurately known mixture of CO2 and nitrogen is introduced into the inspired gas, simulating VO2 by dilution and VCO2 by addition of CO2. The ratio of VCO2:VO2 (respiratory gas exchange ratio, R) in the "expired gas" should be [FGCO2/(1-FGCO2)] x [(1-FIO2)/FIO2], where FGCO2 is the fraction of CO2 in the diluting gas and FIO2 is the fraction of O2 in the inspired gas. R is independent of the flow rate of the diluting gas or the rate of ventilation of the test lung. Using a mixing chamber-mass spectrometer, we found that R calculated from measurement of CO2 and O2 concentrations in the simulated mixed expired gas closely matched the predicted R for FIO2 = 0.21-0.50. On the other hand, when an automated gas exchange measurement device was tested, R was sometimes excessively high, especially for FIO2 greater than 0.35. This method, using a single diluting gas and without precision flowmeters, may be useful for periodic testing of respiratory gas exchange instruments in the intensive care unit. If a discrepancy is found between measured and predicted R, measurements should not be relied upon until further calibration or repairs can be effected.

Humans↗
PubMedDate not supplied

Studies on the nature of the primary reactions of photosystem II in photosynthesis. I. The electrochromic 515 nm absorption change as an appropriate indicator for the functional state of the photochemical active centers of system II in DCMY poisoned chloroplasts.

The field indicating electrochromic 515 nm absorption change has been measured under different excitation conditions in DCMU poisoned chloroplasts in the presence of benzylviologen as electron acceptor. It has been found: 1. The amplitude of the 515 nm absorption change is nearly completely suppressed under repetitive single turnover flash excitation conditions which kinetically block the back reaction around system II (P. Bennoun, Biochim. Biophys. Acta 216, 357 [1970]). 2. The amplitude of the 515 nm absorption change measured under repetitive single turnover flash excitation conditions which allow the completion of the back reaction during the dark time between the flashes (measuring light beam switched off) amounts in the presence of 2 mum DCMU nearly 50% of the electrochromic 515 nm amplitude obtained in the absence of DCMU. In DCMU poisoned chloroplasts this amplitude is significantly decreased by hydroxylaminhydrochloride, but nearly doubled in the presence of CDIP+ascorbate. 3. The dependence of the 515 nm amplitude on the time td between the flashes kinetically resembles the back reaction around system ?II. The time course of the back reaction can be fairly described either by a second order reaction or by a two phase exponential kinetics. 4. 1,3-dinitrobenzene (DNE) or alpha-bromo-alpha-benzylmalodinitril (BBMD) reduce the 515 nm amplitude in DCMU poisoned chloroplasts, but seem to influecne only slightly the kinetics of the back reaction. 5. The dependence of the 515 nm amplitude on the flash light intensity (the amplitude normalized to 1 at 100% flash light intensity) is not changed by DNB. Based on these experimental data it has been concluded that in DCMU poisoned chloroplasts the amplitude of the 515 nm absorption change reflects the functional state of photosystem II centers (designated as photoelectric dipole generators II) under suitable excitation conditions. Furthermore, it is inferred that in DCMU poisoned chlorplasts the photoelectric dipole generators II either cooperate (probably as twin-pairs) or exist in two functionally different forms. With respect to BBMD and DNB it is assumed that these agents transform the phtooelectric dipole generators II into powerful nonphotochemical quenchers, which significantly reduce the variable fluorescence in DCMU-poisoned chloroplasts.

Benzyl Compounds↗
PubMedDate not supplied

Studies on the nature of the primary reactions of photosystem II in photosynthesis. II. The modification of the functional integrity of the photochemical active centers of system II by a alpha-bromo-benzyl-malodinitril and accompyaning effects on chloroplasts.

The effect of alpha-bromo-alpha-benzylmalodinitril (BBMD) on the oxygen evolution and on the absorption changes at 515 nm and 704 nm has been investigated in spinach chloroplasts. It has been found: 1. Under repetitive flash excitation conditions, where the back reaction around system II is practically excluded for kinetical reasons, BBMD does not resotre the 515 nm absorption change in DCMU poisoned chloroplasts. 2. Under single flash excitation conditions, where the back reaction around system II becomes prominent in the presence of DCMU, BBMD moderately inhibits this back reaction. The deleterious effect is pronounced by preillumination with short flashes during the BBMD incubation period of the chloroplasts in the absence of DCMU. 3. Incubation of the chloroplasts with BBMD leads to an activity loss of oxygen evolution which increases with the time td between the repetitive short excitation flashes and with the dark incubation time. Preillumination during the incubation period with tbbmd significantly enhances the effect. 4. In the absence of artificial electron acceptors BBMD suppresses in DCMU poisoned chloroplasts the 704 nm absorption change reflecting an internal cyclic electron flow around system I. On the other hand the linear electron transport at system I mediated by DCIP plus ascorbate as electron donor couple and benzylviologen as electron acceptor is not distrubed by BBMD. 5. BBMD incubation of chloroplasts accelerates the decay rate of the field indicating 515 nm absorption change. Based on these experimental findings the conclusion has been drawn, that -- in contrast to the assumption of Brandon and Elgersma (Biochim. Biophys. Acta 292, 753--762 [1973]) -- BBMD does not accept electrons from the primary electron acceptor X 320 of system II in DCMU poisoned chloroplasts. BBMD rather acts as a system I electron acceptor. Furthermore, BBMD exerts deleterious effects on the center of photosystem II, accompanied by a weak ADRY-effect on the water-splitting enzyme system Y. As a tentative explanation of the BBMD-action on system II it is assumed that BBMD transforms the photochemical centers of system II into dissipative energy sinks.

Benzyl Compounds↗
PubMedDate not supplied

Indirect evidence for a very fast recovery kinetics of chlorophyll-aII in spinach chloroplasts.

The 690 nm absorption change reflecting the turnover of the system-II-reaction center chlorophyll, Chl-aII (often referred to as P 680), has been investigated under different experimental conditions in spinach chloroplasts. A comparison was made with oxygen evolution and with absorption changes of Chl-aI measured at 703 nm, both indicating the number of electrons produced by system II. It was found: 1. The dependency on actinic flash intensity of the initial amplitudes of the measured 690 nm absorption change, deltaalpha0(Chl-aII) in Tris-washed chloroplasts is similar to that for the total amplutude of the 703 nm absorption change, deltaalpha0(Chl-aI) in normal chloroplasts, and can be described by an exponential function. On the other hand, deltaalphao(chl-aII) in normal chloroplasts exhibits a more complex biphasic dependency and much higher flash intensities are required for saturation. 3. Unver repetitive flash group excitation and in the presence of an ADRY(= acceleration of the deactivation reactions of the water-splitting enzyme system Y)-reagent the initial amplitude of the 690 nm absorption change oscillates in the same characteristic pattern as the oxygen evolution. 4. The initial amplitude of the 690 nm absorption change, deltaalpha0(Chl-aII), IN Tris-washed chloroplasts becomes significantly smaller (more than 50%) by the addition of system-II-electron donors (benzidine, p-phenylendiamine, tetraphenylboron), whereas the total amplitude of the 703 nm absorption change, detalalpha0)Chl-aI) increases 3-4-fold. In order to explain these results, the existance of a very fast reduction kinetics of Chl-aII+ is postulated, which is not detectable by our measuring equipment. The half time of this reaction is less than or equal to mus. Reaction centers with the very gast "undetected" Chl-aII+-reduction are photochemically transformed into slower one by double hit processes with a comparatively low quantum yield. Furthermore, it is inferred, that the dark recovery kinetics of Chl-aII is dependent on be charge accumulation state of the watersplitting enzyme system Y. This phenomenon is shown to explain also the oscillation pattern of delayed fluorescence. On the basis of the present results two alternative reaction schemes for the functional organization of the electron transport on the donor side of system II are discussed.

Chlorophyll↗