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Biomedical subjects

F Scheibe

Publications and source records attributed to F Scheibe.

At least 37 records · Page 2Linked to original sources
PubMed1984

On sources of error in the biochemical study of perilymph (guinea-pig).

Contamination of perilymph with other fluids (cerebrospinal fluid, tissue fluid, blood, endolymph) together with sampling, anaesthesia, surgical intervention or food intake of the animals may considerably affect the analytical result. The numerous possible artefacts seem to be the main reason why varying values are given in the literature for the same chemical component of perilymph. This is also partly true of cerebrospinal fluid and blood. The effect of some sources of error on selected chemical components of perilymph, cerebrospinal fluid and blood is briefly summarized.

Anesthesia↗
PubMed1984

Is there a relationship between genetically determined haptoglobin phenotype and insulin-dependent diabetes mellitus (IDDM)?

The possible relationship between genetically determined haptoglobin phenotype and insulin-dependent diabetes (IDDM), circulating insulin antibodies and the occurrence of microangiopathy was studied in 144 IDDM. There were no differences regarding the distribution of Hp-phenotypes in 144 patients in comparison with a control population (n = 1726). Irrespective of the Hp-phenotype, the degree and severity of diabetic complications (retinopathy and/or nephropathy) significantly increased with the duration of diabetes. There was no relationship between Hp-phenotype and diabetic microangiopathy (retinopathy, nephropathy). No association existed between Hp-phenotype and the percentage of insulin antibody binding. Regardless of the Hp-phenotype, the insulin antibody concentration decreased with increasing duration of diabetes. Insulin binding parameters (maximum binding capacity and equilibrium dissociation constant) were found to vary considerably with the Hp-phenotypes among IDDM. For a given duration of diabetes the equilibrium dissociation constant increased significantly in the range from Hp 1-1, Hp 2-1 to Hp 2-2 phenotype. There was a direct relationship between the logarithm of the equilibrium dissociation constant and the degree of metabolic control, i.e. the lower the dissociation constant the better the metabolic balance. In conclusion, the results do not provide support for a putative relationship between Hp-phenotype and IDDM. However, differences between insulin binding parameters, in dependence on the Hp-phenotype may be of clinical importance.

Adolescent↗
PubMed1983

[Total lactate dehydrogenase activity of perilymph, plasma and cerebrospinal fluid in unstressed and noise stressed guinea pigs].

The total activity of lactate dehydrogenase (LDH) of perilymph (PL), plasma, and cerebrospinal fluid (CSF) of unexposed and sound-exposed guinea pigs was examined with due consideration of the principal sources of error. To test the purity of PL samples, protein, potassium, and sodium were determined simultaneously (Table 1). The LDH was analysed fluorometrically. It was found that there are considerable differences in the LDH activities of PL, CSF, and plasma (Table 2). The mean activity of PL was three to four times higher than that of CSF and only about half that of plasma. No significant difference was found between the PL in scala tympani and scala vestibuli. The most frequent LDH values of the individual fluids (Fig. 2) were somewhat lower than the mean values calculated. Immediately (less than or equal to 60 min) after exposing the animals to wide-band noise at an intensity of 140 dB SPL for 10 min, the mean PL values of the scala tympani and scala vestibuli were found to be somewhat higher than in unexposed animals (Table 3). Eighteen hours after the exposure, slightly higher activity was only detectable in PL of the scala vestibuli. The differences were not found to be significant. The LDH values of CSF and plasma remained unchanged both less than or equal to 60 min and 18 h after noise exposure.

Animals↗
PubMed1982

[Microflame-photometric estimation of sodium and potassium for testing the purity of inner ear fluids (author's transl)].

A simple micromodification of simultaneous flame-photometric estimation of sodium and potassium concentration in sample volumes of 0.1 microliter is described for testing the purity of inner ear fluids, especially of perilymph. The precision of the method is about 10% (calibration standards, Table 2) and depends mainly on the precision of measuring the small sample volumes. The method has been used for examining cerebrospinal fluid, perilymph, and endolymph samples of guinea pigs. The increased perilymphatic potassium (Fig. 1a) and endolymphatic sodium values suggest a more or less substantial contamination of the tested samples and underline the necessity of checking the purity of inner ear fluid samples which are used in biochemical analysis.

Animals↗
PubMed1981

[Postmortem changes in the perilymphatic lactate and pyruvate concentrations of guinea pigs. (author's transl)].

Lactate and pyruvate of perilymph (PL) were studied 30, 60, and 120 min postmortem. During this period the mean lactate concentration of scala tympani and scala vestibuli increased from 4.8 mmol/l found intravitally to 17.8 and 15.1 mmol/l, respectively, whereas pyruvate decreased from an average of 0.33 to 0.10 mmol/l (fig. 1). These inverse changes of concentration yield postmortem lactate/pyruvate quotients which are more than one order of magnitude higher than the quotients found intravitally (Table 1). In comparative tests of blood samples carried out 30, 60, and 120 min after the sampling (Fig.1), the lactate increase was found to be markedly lower than in postmortem PL. The substantial metabolite changes in PL seem to be caused by glycolytic activity of all cochlear structures that are in direct contact with PL. The decrease of pyruvate level is probably due to a shift of the lactate-pyruvate equilibrium (lactate dehydrogenase system) in PL. The blood vessels in the perilymphatic space can be neglected as postmortem metabolite source of PL.

Animals↗
PubMed1981

[On the glucose, pyruvate, and lactate concentration of perilymph, blood, and cerebrospinal fluid of unexposed and sound-exposed guinea pigs under ethyl urethane anesthesia (author's transl)].

Glucose, pyruvate, and lactate of perilymph (PL), blood, and cerebrospinal fluid (CSF) of unexposed and sound-exposed guinea pigs under ethyl urethane anesthesia were examined with due consideration of the principal sources of error. The animals had fasted for 15--20 h before the experiment to stabilize the blood glucose level. The metabolites were determined enzymatically by means of fluorescence measurements. It was found that the glucose levels depend not only on ingestion but also on the duration of anesthesia of the animals before sampling. The mean values of the scala tympani and scala vestibuli PL and CSF did not differ significantly, being about half those of blood or plasma immediately (10--20 min) after introducing anesthesia (Table 2). This concentration difference is in disagreement with the original ultrafiltration hypothesis of PL, suggesting a blood-PL barrier for glucose. The dependence on the duration of anesthesia and on the animals' ingestion before sampling appears to be an important cause of the differences in glucose data published in literature hitherto. No influence of anesthesia on pyruvate and lactate concentrations was observed. Data obtained on unexposed control animals (Tables 3 and 4) confirmed our earlier metabolite findings (Scheibe et al. 1976, 1981). No major changes in glucose, pyruvate, and lactate concentration of PL, blood, and CSF were detectable immediately after 1 h of exposure to wide-band noise at an intensity of 120 dB SPL. The present lactate findings confirmed our earlier exposure experiments (Scheibe et al. 1976), but they did not agree with the information given by Schnieder (1974).

Animals↗
PubMed1981

[Lactate and pyruvate concentrations in perilymph, blood, and cerebrospinal fluid of guinea pigs].

Lactate and pyruvate were studied comparatively in perilymph (PL), blood, and cerebrospinal fluid (CSF) of anesthetized guinea pigs. Arterial blood pressure, heart and respiration rate (Fig. 1), and arterial blood-gas state (Table 2) were simultaneously checked in a group of the animals. The metabolites were determined enzymatically by using the fluorometric technique. The studies have shown (Table 1) that both the lactate and the pyruvate concentrations are in PL at a similar rate (about 3:1) higher than in native blood and also higher than in CSF. The metabolite values of blood, especially the lactate values, were lower when blood was taken alone, e.g., more physiological, than in the case when CSF and PL had been sampled before. The lactate/pyruvate ratios of Pl are somewhat higher than the blood ratios. The ratio of CSF was found to be lower. The high metabolite levels in PL suggest an intracochlear origin. A direct perilymphatic lactate origin could not be detected.

Animals↗
PubMed1979

[Blockage of cochlear aqueduct for examination of perilymph (guinea pig) (author's transl)].

To prevent the perilymph (guinea pig) from contamination with CSF during the sampling the aqueductus cochleae (AC) was blocked by injection of tissue adhesive into the meningeal aperture. The control of an exact blockage of AC was carriedout by examination of perilymph-outflow after opening the cochlea (injection of fluorescein-Na into the CSF-space), analysis of perilymph-protein-concentration, macroscopic and microscopic examination of the temporal bones. In all cochleae we have found the same morphological structures, notwithstanding whether the AC was blocked (for a time from 30 min to 7 weeks) or not: The cochlear aqueduct is filled with a mesh of mesenchymal tissue, which grows more dense towards the cochlear aperture andcontinues into the round window membrane. From scala tympani the AC is always limited by one layer of cells forming a sort of membrane (under light microscope). It seems possible that CSF moves in the inner of the round window membrane between AC and subepithelian space of middle ear mucosa, whereas perilymph of scala tympani is not in direct contact with the flow of CSF. The scala tympanic side of the round window membrane may be a big area for diffusion and there also may be an exchange between CSF and perilymph. The outflow of CSF into the cochlea after experimental opening of the cochlea is an artifact, caused by damage of pressure equilibration between CSF-space and cochlea. 30 min and 5--7 weeks after blockage no morphologicaland electrophysiological alterations from those of the control ears were to be seen. The protein concentration, however, increased significantly 5--7 weeks after blockage from normally about 200 mg/100 ml toalmost the double especially in the scala tympani (see Table 1).

Action Potentials↗
PubMed1976

[Comparative studies of lactate concentration in the perilymph, blood and cerebrospinal fluid of normal and sound exposed guinea pigs (author's transl)].

The paper deals with comparative studies of lactate concentration in the perilymph (PL) of scala tympani and of scala vestibuli, arterial and venous blood, serum and cerebrospinal fluid (CSF) of normal and sound exposed guinea pigs, special consideration having been given to possible sources of error in the methods employed. Lactate was determined enzymatically using a micromodification of the Boehringer UV-test combination adapted to 1 mul PL. The lactate concentrations in the PL of scala tympani and scala vestibuli did not differ significantly. The mean values amounted to 4.5-5.2 mM/l in the case of the opened and of the unopened subarachnoid space (Table 1). The lactate concentrations in the PL of both cochlea scales were significantly higher already ten minutes post-mortem. In the exposure experiments the animals were unilaterally exposed to sound for 1 h in an acoustically isolated system using a wide-band noise at an intensity of 120 dB SPL for one series and 2-kHz pure-tone at intensities of 112 and 122 dB SPL for two other series. We did not detect any changes in the lactate concentrations neither in the PL nor in the blood and in the CSF, following sound exposure (Table 2 and 3). The lactate concentrations of arterial and venous blood and CSF did not differ significantly. The mean values amounted to 1.4-1.8 mM/l (Table 2). However, if blood was not deproteinized or centrifuged immediately after being taken, the lactate concentration increased markedly. A comparison of the present results has shown that the lactate concentration in the PL is about three times as high as in blood and in CSF. This difference in concentration suggests that the PL lactate is of intracochlear origin and that glycolytic processes take place in the inner ear also under normal conditions. Systematic studies of additional metabolic parameters must be conducted before a definitive physiological interpretation of the present analytical results can be given.

Animals↗
PubMed1976

[Otitis media and cochlea. Morphological and biochemical studies in guinea pigs (author's transl)].

The paper deals with: 1. the protein concentration in the perilymph (PL), the serum and the cerebrospinal fluid (CSF), 2. the protein pattern in the PL and 3. histological findings in the middle and inner ear in unilaterally ear-infected guinea pigs. The studies were performed 6 h to 21 days post infectionem (Fig. 1). The pathological changes in the middle ear, which, in most cases, were limited to the infected ear, were initially evaluated under the operating microscope and divided into 4 stages. The analytical and histological results were presented as functions of these stages. As the inflammation intensity increased, the protein concentration in the PL of the infected ears increased to a level exceeding that of the normal value more than ten times (Fig. 2). However, in the serum and in the CSF this concentration remained unchanged. Likewise, no significant protein increase in the PL of the contralateral ears was detectable in most cases. As the inflammation intensity increased, the number of the precipitation lines detectable immunoelectrophoretically increased in the PL of the infected ears (Fig. 3). An increase in the alpha1- and gamma-globulins and a decrease in Albumin was found by electrophoresis on cellulose acetate strips (Tab. 3). The histological findings correlated with initially established inflammatory stages of the middle ear mucous membrane (Tab. 4). As the inflammation intensity increased, the round window, too, was changed pathologically, so that in some cases of purulent otitis media middle ear secretion could enter the cochlea. The protein increase in the PL immediately after the infection is probably due to an increase in the blood vessel permeability in the inner ear.

Animals↗
PubMedDate not supplied

[Protein concentration in the guinea-pig perilymph].

The protein concentration of the guinea pig perilymph was investigated systematically using a micro-modification of the method of Lowry et al. Perilymph of scala vestibuli and of scala tympani was obtained from living animals and immediately post mortem by various methods. In living animals it is especially difficult to obtain samples without blood contamination. Another problem in the obtaining of perilymph from living animals is the contamination of tympanic perilymph samples with cerebrospinal fluid. This contamination diminishes the protein concentration of perilymph to a high degree. When the subarachnoid space is opened suboccipitally before perilymph extraction, there is no significant difference between protein content in tympanic and vestibular perilymph. The mean protein concentration in both cochlea scales is about 150 mg/100 ml. When samples are extracted post mortem from animals perfused intra-arterially, mean values of protein are in the same range. Without perfusion of animals, the mean value of tympanic samples extracted post mortem is significantly higher. Causes of artefacts in perilymph investigations are discussed.

Animals↗