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Biomedical subjects

M Schmidt

Publications and source records attributed to M Schmidt.

At least 757 records · Page 42Linked to original sources
PubMed1987

The cochlea in gerbilline rodents.

The inner ears of 5 different gerbil species are compared on the basis of cochlear microphonic recordings, serial sections and computerized quantitative reconstructions of the cochleae and their specific morphological structures. The hearing range of most gerbils is below 20 kHz. Some species are extremely sensitive in the frequency range of 1-4 kHz. This special sensitivity is reflected in, among other features, the following cochlear structures and their suggested functions: (1) the rapid width increase of the basilar membrane in the basal portion of the cochlea provides additional space for the representation of lower frequencies at the expense of higher frequencies; (2) the large hyaline mass and the cells of Claudius and Hensen in the medial and apical portions of the cochlea influence the vibratory properties of the cochlear partition, and (3) the specialized structures of the cochlea may be an adaptation to the acoustical environment in arid habitats.

Adaptation, Biological↗
PubMed1987

Proteolytic activities in bronchoalveolar lavage fluid of interstitial lung diseases: correlation to stage and prognosis.

In 18 patients with sarcoidosis, 10 patients with idiopathic pulmonary fibrosis (IPF), 6 patients with exogen allergic alveolitis (EAA), and 9 control persons we investigated proteolytic activities in bronchoalveolar lavage fluid (BALF). In lymphocyte-macrophage alveolitis (i.e. sarcoidosis and EAA) proteolytic activities in BALF were low, but the activities correlated with lung function deterioration within 1 year. In IPF (i.e. in neutrophil alveolitis) we found a striking correlation between proteolytic activities and stage of disease: high activities correlated with early stages, lower values with late stages of IPF. Measurement of proteolytic activity in BALF seems to be of interest to differential diagnosis and to prognosis of interstitial lung disease.

Adult↗
PubMed1987

[Multicenter study of the treatment of highly malignant non-Hodgkin's lymphomas with polychemotherapy (CHOPV) and irradiation].

In a multicenter study 46 untreated patients with highly-malignant non-Hodgkin's lymphomas stage II-IV received 6 courses of the following drug combination: cyclophosphamide 750 mg/m2 i.v. day 1, adriamycin 50 mg/m2 i.v. day 1, vincristine 2 mg i.v. day 1, prednisolone 100 mg p.o. days 1-5, and etoposide 100 mg/m2 i.v. days 3-5. Between courses 4 and 5 an involved field irradiation with a total dose of 25 Gy was employed. The overall response rate was 91%, with 38 patients achieving a complete remission (82%), 4 patients achieving a partial remission (9%), and 4 patients showing no response (9%). During a median follow-up period of 34 months 16 out of 38 patients relapsed, 4 of them achieving a second complete remission with the same drug regimen. A maintained complete remission up to 52 months was seen in 51% of all patients initially achieving CR. The overall survival curve shows a plateau at 60% at 30 months, while disease-free survival shows a plateau at 51% at 36 months. Mean side effects of this drug regimen were alopecia (89%), nausea/vomiting (76%), and leukopenia (61%). No therapy-related deaths were reported. The results of this study demonstrate that this treatment produces high complete remission rates and that the majority of these patients achieves long-term disease-free survival.

Adolescent↗
PubMed1987

Renin-angiotensin system in sepsis.

The time course of the components of the renin-angiotensin system was investigated in the plasma of three patients on the intensive care unit. Two of them, which were both polytraumatized, suffered from adult respiratory distress syndrome (ARDS). All patients had sepsis and impaired pulmonary and renal function. Plasma samples were investigated for up to two weeks, in which time all three patients showed a decrease in their angiotensin converting enzyme (ACE) plasma concentration. Two of the patients with deteriorating renal function had three to four times elevated angiotensinogen (Ao) plasma levels, which were measured by both the direct and indirect radioimmunoassay. The ratio of the mean values between both assays was 1:1 in two patients and shifted to higher values in the direct assay in the third patient. This suggests that higher amounts of des-AngI-angiotensinogen were present in the latter patient, because "inactive" Ao is also detected by the direct assay. The decrease in active Ao may be caused by an up to twenty times elevated plasma renin activity (PRA). The PRA was correlated with the angiotensin I (AngI) plasma levels. However, at PRA values higher than 200 pmol AngI/ml/h this correlation decreased because of the rapid substrate consumption. In addition there was a good correlation between AngI and AngII plasma levels in two patients which could not be observed in the patient with the highest PRA and AngII values. A relationship between plasma ACE concentration and AngII formation could not be observed. Thus in two of the three septic patients the components of the renin angiotensin system were extremely stimulated at very low blood pressure values. These data show, that it is reasonable to follow the time course of the components of the renin angiotensin system in single patients. In addition it is demonstrated that the direct measurement of Ao is a valid supplement in the diagnosis of the renin angiotensin system.

Acute Kidney Injury↗
PubMed1987

Vascular effects of selective dopamine receptor agonists and antagonists in the rat kidney.

The renal vascular effects of dopaminomimetics and dopaminolytics were studied in the isolated perfused rat kidney after pretreatment with phenoxybenzamine (10(-5) M) and sotalol (10(-5) M) and after contraction of the vascular bed with prostaglandin F2 alpha. The DA1- and D1-selective antagonist, SCH 23390, antagonized competitively the relaxation induced by dopamine (pA2 = 9.7 +/- 0.08, m +/- S.D.). On the other hand, (+/-)-DO 710, a D2-preferential benzamide, only antagonized the renal vascular response to dopamine at a concentration 30 times higher than that active on D2 receptors. The ergot derivative, quinpirole, a selective agonist for DA2 and D2 receptors had no renal vascular dopaminomimetic activity, whereas (-)-EOE, a D2-selective ergoline, seemed to be a partial agonist, but 10 times less potent than dopamine. These results confirm the existence of DA1 receptors on the vascular bed of isolated rat kidney but rule out the presence of DA2 receptors. They also reinforce the analogy between DA1 and D1 dopamine receptors.

Animals↗
PubMed1987

[Effects of conversion enzyme inhibitors on the synthesis of angiotensin II by the isolated rat kidney].

On the isolated perfused rat kidney, angiotensin-converting-enzyme activity was evaluated by two approaches: one, biochemical, through the measurements of the enzymatic activity on renal homogenate, the other, pharmacological, through the vasoconstrictor response to angiotensin I. Renal tissue angiotensin-converting-enzyme activity was not modified by setting the kidney under perfusion with a modified Krebs-Henseleit solution but was inhibited after addition of captopril into the perfusion medium (10(-5) M, 100 p. 100 inhibition) or after pretreatment of the animals with ramipril (10 mg/kg/day over 3 weeks, per os, 60 p. 100 inhibition). On the isolated perfused rat kidney, angiotensin I and angiotensin II induced a concentration dependent renal vasoconstriction (EC50 = 1.05 +/- 0.18 X 10(-8) and 0.11 +/- 0.05 X 10(-8) M) which was competitively antagonized by saralasin, an angiotensin II receptor antagonist. Addition of angiotensin-converting-enzyme inhibitors to the perfusion medium (captopril or ramiprilat, 10(-5) M) or pretreatment of the animals with ramipril (50 mg/kg, i.p. the day before or 10 mg/kg/day over 3 weeks, per os) only shifted the angiotensin I concentration-response curve to the right by a factor 3 to 4. The residual vasoconstrictor effect of angiotensin I was abolished by 10(-5) M saralasin and remains linked to a local generation of angiotensin II. Our results suggest that, on the isolated perfused rat kidney, besides the angiotensin-converting-enzyme, an iso-enzyme may also be able to generate angiotensin II.

Angiotensin I↗
PubMed1987

Suppression of the plasma aldosterone to renin activity ratio in anaesthetized cats after pharmacological stimulation of the peripheral arterial chemoreceptors with almitrine bismesylate.

In chloralosed, non-vagotomized, spontaneously breathing cats the peripheral arterial chemoreceptors were stimulated by intravenous infusion of almitrine bismesylate (Vectarion, 0.20 mg/kg). Within 5 h after administration of the drug, a decline of both the mean systemic arterial blood pressure and the effective renal plasma flow, as well as an increase of the plasma renin activity (PRA) and the plasma aldosterone concentration (PAC) was observed. But as the PAC increase was less than that of PRA, a highly significant suppression of the PAC to PRA ratio was noted. The results indicate that not only whole body altitude hypoxia, but also stimulation of the peripheral arterial chemoreceptors in normoxic animals lowers the PAC-to-PRA ratio. It remains to be verified experimentally whether there exists a specific reflex influence of the peripheral arterial chemoreceptors on the renin-aldosterone relationship.

Aldosterone↗
PubMed1987

[Color-coded Doppler echocardiography in an infant with an aortopulmonary window. A pre- and postoperative study].

The clinical value of the new two-dimensional color Doppler echocardiography (2D-color Doppler) for the non-invasive visualization of shunting across the aorticopulmonary window (APW) in a 5-month-old infant is described. The quality of the color-coded bloodflow mapping may be equal to that of angiography. The sensitivity of the method is demonstrable by the minimal diastolic shunt across the operated APW. The 2D-color Doppler may enhance the diagnostic impact of 2D-echocardiography, especially by improving diagnostic accuracy non-invasively in critically ill infants.

Aorta, Thoracic↗
PubMed1987

Free radical-mediated damage during myocardial ischemia and reperfusion and protection by carnitine esters.

Ischemic injury may be exacerbated by readmission of oxygen into the myocardium, probably due to the formation of free radicals and their interaction with membrane lipids. We tested the hypothesis that ischemic myocardial damage is potentiated during reperfusion with excess free fatty acids in the globally ischemic rat heart, and in parallel studies, we investigated the protective effects of carnitine derivatives. Intermittent ischemia, i.e. three 20 min periods of ischemia followed by 10 min reperfusion each, was induced in isolated working rat hearts perfused with either glucose (11 mM) alone or glucose with palmitate (11 mM and 1.2 mM). The ischemic coronary flow was reduced to 1.1 ml/min in a low-flow group and equalled 0 ml/min in a no-flow group. Loss of functional recovery in the low-flow and no-flow group was more pronounced when palmitate was present in the perfusate. This was associated with increased levels of long-chain acyl-CoA esters in the palmitate perfused hearts. Malondialdehyde, an indicator of free radical formation, was elevated in both low-flow and no-flow groups when either substrate was used. We therefore suggest that free radical formation contributes to myocardial injury in intermittent ischemia. The mechanism of free radical formation and their sites of action have not yet been completely elucidated - the peroxidation of membrane lipids is probably involved, particularly in the presence of high palmitate. The protective effect of the carnitine derivatives D-propionylcarnitine, L-propionylcarnitine and propionylcarnitine taurine amide was studied in the no-flow hearts (Table 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Influence of infusion of deoxycorticosterone acetate on the responses of kidney function elicited by stimulation of the peripheral arterial chemoreceptors with almitrine bismesylate in anaesthetized rats.

In two groups of male, normotensive, spontaneously breathing rats in chloralose-urethane anaesthesia the peripheral arterial chemoreceptors were stimulated by intravenous infusion of almitrine bismesylate (0.25 mg/kg). The experiments were carried out in moderate osmotic diuresis. In one series desoxycorticosterone acetate (DOCA) was infused at a rate of 35-40 ng/min.100 g body weight. Urine was collected via a bladder catheter. Kidney hemodynamics as well as tubular and excretory function were determined using the clearance-technique. In both groups of animals administration of almitrine caused an increase of breathing rate as well as an increase of the oxygen tensions and the pH-values in the arterial blood. Mean systemic arterial blood pressure, effective renal plasma flow and glomerular filtration rate decreased slowly with the time of the experiments, whereas renal hemodynamic resistance tended to increase both in the control and in the DOCA treated group. In both groups of animals intravenous infusion of almitrine was followed by an inhibition of renal tubular sodium reabsorption and an increase of both the absolute and the fractional salt excretion. The data indicate that arterial chemoreceptor stimulation in rats causes an inhibition of renal tubular sodium reabsorption which does not result from a reduced tubular action of mineralocorticoid hormones.

Almitrine↗
PubMed1987

[Diagnostic and therapeutic blockade of the celiac ganglia].

Neurolytic celiac plexus block is the therapy of choice for visceral upper abdominal pain that is resistant to therapy. In order to ensure that the treatment is indicated a temporary block for diagnostic purposes (application of a local anesthetic) has to be carried out. A diagnostic block can be performed as a blind puncture according to anatomic criteria if new computed tomograms are available providing the necessary information on the patient's anatomy. In 18 patients who underwent a diagnostic block by this procedure no side effects could be observed. If neurolytic substances (e.g. ethanol 96%) are used, a contrast medium should be added to make roentgen control and documentation possible. Computed tomography is a very suitable procedure for these purposes. The location, angle and depth of the puncture can be calculated by the computer tomograph. Of 14 patients in whom we performed a CT-guided block of the celiac ganglion, 10 were free from pain afterwards or showed considerably reduced pain symptoms. The side effects that could be observed were but slight and passed after a few days.

Abdomen↗
PubMed1987

[Nihil nocere!].

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Adolescent↗