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H Schwarze

Publications and source records attributed to H Schwarze.

12 recordsLinked to original sources
PubMed2002

Analysis of the long-term behavior of solute transport with nonlinear equilibrium sorption using breakthrough curves and temporal moments.

We analyzed the long-term behavior of breakthrough curves (BTCs) and temporal moments of a solute subjected to Freundlich equilibrium sorption (s = kc(n)). For one-dimensional transport in a homogeneous porous medium, we derived a power-law relation between travel time, tau, and solute displacement, chi, with the exponent being equal to the Freundlich n exponent. The mean solute velocity, derived from the first time moment, was found to change as tau(n-1). For n values larger than 0.66, the second time moment could be related to c chi(2/n), where c is a constant. An approach based on the use of a critical concentration was developed to estimate the presence of the asymptotic regime in the tail of the BTC. This approach was tested successfully using numerical case studies. One-dimensional numerical simulations with varying values of k, n and initial mass were run to verify the closed form analytical expressions for the large time behavior of temporal moments and the tailing part of breakthrough curves. Good agreement between the slope of the tailing part of log-log transformed BTCs and the predicted slope using asymptotic theory was found. Asymptotic theory in general underestimated the magnitude of the concentration in the tail. The quality of the estimated concentrations in the tail improved for small values of the dispersivity. Experimental BTCs of uranin and benazolin were analyzed in combination with sorption/desorption batch experiments using asymptotic theory. A good agreement between the value of n parameter derived from desorption experiment with benazolin and the value of the n parameter derived from the tail of the BTC was found.

Adsorption↗
PubMed2001

Mitochondrial ATP dependent potassium channels mediate non-ischemic preconditioning by tachycardia in dogs.

Brief episodes of tachycardia without myocardial ischemia prior to a coronary occlusion decrease myocardial infarct size in dogs. This non-ischemic preconditioning is mediated by adenosine. Because ischemic preconditioning is mediated through ATP dependent potassium channels, particularly the mitochondrial ones, we studied whether non-ischemic preconditioning is also mediated through these channels. In anesthetized dogs heart rate was kept constant at 120 cycles/min and aortic pressure changes were damped. Myocardial infarction was induced by occlusion of the anterior descending coronary artery for 60 min and reperfusion for 270 min. In a control group the infarct size (necrotic volume/risk region volume x 100) was 15.8+/-1.5%. Preconditioning with five periods of tachycardia, 5 min in duration each at 213 cycles/min with intervening periods of 5 min of basal heart rate at 120 cycles/min, reduced the infarct size by 45.6% (p < 0.05) with respect to the control group. This effect was completely reverted by the blockade of ATP dependent potassium channels with glibenclamide or 5 hydroxydecanoate (a specific blocker of mitochondrial ATP dependent potassium channels) prior to preconditioning. These effects were not due to differences in collateral flow, risk region size or hemodynamic variables between the groups. These results show that mitochondrial ATP dependent potassium channels mediate non-ischemic preconditioning by tachycardia in dogs.

Adenosine↗
PubMed1997

A double-blind study comparing paroxetine and maprotiline in depressed outpatients.

A double-blind multicenter randomized parallel group study comparing paroxetine and maprotiline was carried out in a total of 544 outpatients. Included were patients with varying degrees of severity of depressive symptoms who fulfilled modified RDC criteria for either Minor or Major Depression and showed a HAMD-17 score of > or = 13. No concomitant benzodiazepine treatment was allowed. Duration of treatment was 6 weeks, after an initial wash-out period. Doses were fixed during the first 3 weeks of treatment, patients receiving either 20 mg paroxetine or 100 mg maprotiline daily. An option for dose escalation was provided for insufficient responders after 3 weeks. The weekly assessments comprised rating of the HAMD-17, MADRS, BRMS, RDS, HAMA, CAS, and CGI scales and registration of adverse events by non-leading questions. An intention-to-treat and a completer analysis were performed. Response was defined as a HAMD-17 reduction of > or = 50% or a HAMD-17 score of < or = 9 at the end of the study or at dropout. The treatment groups were comparable according to demographic data. Overall evaluation indicated equieffective and good antidepressant and anxiety-reducing properties for paroxetine and maprotiline. No persistent significant differences between treatment groups were observed on any assessment instrument. There was no difference in the frequency of observed side-effects, but side-effect profiles were markedly different, as maprotiline patients had more anticholinergic and paroxetine patients more SSRI-typical side-effects.

Adult↗
PubMed1995

20 MHz sonography, colorimetry and image analysis in the evaluation of psoriasis vulgaris.

For objective evaluation of the treatment of psoriasis vulgaris standard techniques are desirable. They should be reproducible, sensitive and non-invasive. In this study non-invasive bioengineering techniques, especially high frequency/high resolution ultrasound for measurement of the healing of psoriasis vulgaris were evaluated. Fifty patients with chronic stationary plaque type psoriasis participated in a prospective study; in each patient two psoriatic plaques were examined by means of sonography, colorimetry and image analysis during treatment until complete resolution had occurred. Skin thickness and density could be quantified by means of high frequency ultrasound. In active psoriatic lesions, an echopoor area underneath the entry echo in the ultrasound image caused by acanthosis and inflammatory infiltrate is typical. Under therapy the thickness of this echopoor area diminishes while its density increases. Intensity of the erythema especially the decrease of erythema through healing could not exactly be quantified with the colorimeter because the 'Lab'-CIE-colour representation system cannot distinguish well enough between the colours red and brown. Image analysis allowed to measure the sizes of the psoriatic plaques and to quantify their resolution under therapy. The measuring of plaque size by the aid of computer based image analysis is possible and useful.

Colorimetry↗
PubMed1994

[Clinical management of hemolytic-uremic syndrome and thrombotic-thrombocytopenic purpura].

BACKGROUND: According to recent research, the hemolytic-uremic syndrome (HUS) and thrombotic-thrombocytopenic purpura (TTP) are variable expressions of the same entity (HUS-TTP) with a common pathomechanism (endothelial cell damage, microthrombi) and common treatment (plasma infusion, plasmapheresis). The condition is still serious with a poor prognosis, and the therapeutic regimen is not yet standardized (cryosupernatant and factor VIII free plasma, steroids, immunoglobulins, anticoagulation, dextrane, prostacyclin, vincristine, splenectomy?). CLINICAL OBSERVATIONS AND REVIEW OF THE LITERATURE: Over an observation period of 15 years we considered the differential diagnosis of HUS-TTP in 34 patients, and treated 11 patients with 12 clinical courses specifically with fresh-frozen plasma (plasmapheresis was additionally performed in 10 of them). The 12 courses were retrospectively evaluated and compared with results achieved in the literature. The mean age of the patients was 43 years (+/- 14), and 9 of the 11 patients were women (2 courses given to one woman). The hemolysis improved in 9 of 12 courses, the cerebral manifestation in 3 of 4 cases, and the thrombocytopenia in 2 of 4 cases. Renal failure responded in only 4 of 9 cases and the response was delayed in these patients. Three patients died: one of brain edema due to TTP-specific cerebral microangiopathy and two due to the underlying disease (lupus erythematosus, mixed connective tissue disease). CONCLUSION: Treatment of HUS-TTP is started with fresh-frozen plasma infusions (1-1.5 liters/day), but plasmapheresis should be added 2 days later (3 x 4 liters/week, whereby 2 liters should be given as fresh-frozen plasma). The administration of fresh-frozen plasma must be continued every day. In resistant cases, specific therapy should not be terminated before 4 weeks.

Adult↗
PubMed1994

Endothelium-derived relaxing factor participates in the transmural distribution of coronary bloodflow.

OBJECTIVE: To study the role of endothelium-derived relaxing factor (EDRF)--which participates in the regulation of coronary vascular tone, but has an unknown role in the transmural distribution of coronary flow--in transmural coronary flow distribution during steady basal flow and during reactive hyperemia in the left ventricular wall of the dog. DESIGN: Sixteen mongrel dogs of either sex weighing between 14 and 24 kg were anesthetized with sodium pentobarbital. The lungs were mechanically ventilated and the thoraces were opened. Circumflex coronary flow was measured with an electromagnetic flowmeter, and its transmural distribution across four layers of the left ventricular wall was measured with radioactive microspheres. Measurements were done during steady basal flow and during peak reactive hyperemia before and after the inhibition of the EDRF synthesis with N-omega-nitro-L-arginine (NNLA). Mean aortic and systolic left ventricular pressures and heart rate were kept constant, and left ventricular end-diastolic pressure increased by only 3.3 mmHg during reactive hyperemia. MAIN RESULTS: NNLA produced a mean decrease of steady basal flow of 22.3 +/- 0.9% (P < 0.01). Flow decreased in all layers of the wall; the decrease, however, was proportionally less in the subendocardium (P < 0.05). During reactive hyperemia (before NNLA), flow was redistributed to the subendocardium (compared with steady basal flow). Administration of NNLA reduced the magnitude of peak reactive flow to all layers in the wall, showing a relative enhancement of flow in the subendocardium. CONCLUSIONS: These results suggest that the EDRF participates in the regulation of coronary bloodflow and its distribution across the left ventricular wall.

Animals↗
PubMed1993

Role of endothelium-derived relaxing factor on coronary blood flow regulation in the dog.

The endothelium plays a key role in the regulation of vasoreactivity. To assess its importance on coronary flow regulation, we studied the participation of endothelium-derived relaxing factor-nitric oxide (EDRF-NO) on coronary reactive hyperemia and on the hyperemia that occurs secondary to an increase in myocardial oxygen consumption. In 15 dogs, the reactive hyperemic response decreased substantially after inhibition of EDRF-NO synthesis with N-omega-nitro-L-arginine (P < 0.01). In contrast, the hyperemia secondary to an increase in myocardial oxygen consumption, characterized by a linear correlation between myocardial oxygen consumption and coronary flow, did not change significantly after inhibition of EDRF-NO production (regression analysis, P > 0.1). Thus EDRF-NO synthesis by the endothelium is an important mechanism mediating the reactive hyperemic response but it does not seem to be essential for the metabolic regulation of coronary vascular resistance during hyperemia induced by an increased metabolic demand on the myocardium.

Animals↗
PubMed1992

Differentiation between major and minor depression.

Though the concept of Major Depression was generated by clinicians using depressed inpatients as models, a polydiagnostic study in 600 psychiatric inpatients with heterogenous psychological disturbances revealed that all six competing operational definitions of Major Depression (including DSM-III-R and ICD-10) were too restrictive to serve as a general concept of depression. Another polydiagnostic study in 500 primary care outpatients showed that more than two-thirds of all non-chronic depressed cases were below the severity threshold of Major Depression: these patients are classified as Depression Not Otherwise Specified (NOS) by DSM-III-R. Loosening of the over-restrictive time criteria would broaden the concept of Major Depression so as to meet the requirements of a general concept of depression, while the definition of Minor Depression below the threshold of Major Depression would add to a reduction of cases of NOS Depression by more than 80%. For the evaluation of antidepressant drugs in outpatient samples, we propose that patients with these modified definitions of Major and Minor Depression be included, provided they meet a minimum severity criterion of 13 or more points on the Hamilton Depression Scale; four-fifths of the modified Major Depression group and one-third of the Minor Depression group do in fact meet this criterion.

Depression↗
PubMed1991

Identification of minor affective disorders and implications for psychopharmacotherapy.

Five hundred general practice patients with functional complaints were studied with the Polydiagnostic Interview (PODI) to see whether DSM-IIIR criteria were able to specify affective disorders satisfactorily. Almost one third of the patients received the diagnosis of depression not otherwise specified (NOS). When Research Diagnostic Criteria were applied to these patients more than 70% received specific diagnoses. A modification of DSM-IIIR algorithms enabled us to further specify diagnoses in subjects with depression NOS. On the 17-item Hamilton Depression Scale many of these patients reached scores of 13 or more which is severe enough to justify a therapy trial with antidepressants.

Adjustment Disorders↗
PubMed1990

A reexamination of end-point and rebound nystagmus in normals.

In order to detail the characteristics of end-point (EPN) and rebound nystagmus (RN), two series of experiments were performed with infrared oculography for measurement of horizontal eye movements. Experiment 1 consisted of EPN recordings during sustained lateral gaze (40 degrees and 50 degrees) in 20 normal subjects. Experiment 2 consisted of recordings of RN in 5 normal subjects. Nine of 20 subjects demonstrated a jerk EPN. EPN almost always appeared immediately and was sustained for 15-25 sec. In Experiment 2, RN occurred in 5 of the 5 subjects who demonstrated EPN. The mean amplitude of RN was always less than that of EPN, and decayed over a 5-10-sec time period. The experiment demonstrated that RN can be evoked in normals even when a fixation target, in a fully lit room, is present.

Adult↗
PubMed1982

[Effect of DL-tryptophan on photic evoked potentials and basic activity of the EEG].

The effects of DL-tryptophan on photic evoked potentials (photic after discharges--PhNE, photic recruitment--PhR, photic evoked primary potential--PhEP) and basic activity of EEG were investigated in freely moving rats with chronically implanted electrodes in various areas of cortex. DL-tryptophan increased the number of PhNE potentials and particularly the number of NE potentials per answered lightflashes (NE/bLB). The effects depend on dosage of DL-tryptophan. The double impulse stimulation confirmed these results. The power spectral show an increased synchronization of the background EEG activity. The results are discussed in connection with local serotoninergic effects and influences on vigilance by 5-hydroxytryptamine.

Animals↗