Biomedical subjects

H Steinhart

Publications and source records attributed to H Steinhart.

At least 19 recordsLinked to original sources

PubMed2006

Consensus meeting: monosodium glutamate - an update.

OBJECTIVE: Update of the Hohenheim consensus on monosodium glutamate from 1997: Summary and evaluation of recent knowledge with respect to physiology and safety of monosodium glutamate. DESIGN: Experts from a range of relevant disciplines received and considered a series of questions related to aspects of the topic. SETTING: University of Hohenheim, Stuttgart, Germany. METHOD: The experts met and discussed the questions and arrived at a consensus. CONCLUSION: Total intake of glutamate from food in European countries is generally stable and ranged from 5 to 12 g/day (free: ca. 1 g, protein-bound: ca. 10 g, added as flavor: ca. 0.4 g). L-Glutamate (GLU) from all sources is mainly used as energy fuel in enterocytes. A maximum intake of 6.000 [corrected] mg/kg body weight is regarded as safe. The general use of glutamate salts (monosodium-L-glutamate and others) as food additive can, thus, be regarded as harmless for the whole population. Even in unphysiologically high doses GLU will not trespass into fetal circulation. Further research work should, however, be done concerning the effects of high doses of a bolus supply at presence of an impaired blood brain barrier function. In situations with decreased appetite (e.g., elderly persons) palatability can be improved by low dose use of monosodium-L-glutamate.

Adolescent↗

PubMed2006

Syntheses of conjugated octadecadienoic acids.

Three approaches for the synthesis of octadecadienoic acids with conjugated double bond systems are presented: synthesis of (10Z, 12Z)-octadecadienoic acid via an enyne-substructure; the use of an educt with a conjugated double bond system for the synthesis of (10E, 12E)-octadecadienoic acid; and the Suzuki cross coupling for the synthesis of (7E,9Z)-octadecadienoic acid.

Fatty Acids, Unsaturated↗

PubMed2005

Influence of maturation on the alteration of allergenicity of green pea (Pisum sativum L.).

The IgE-binding capacity of different maturation levels of green pea seeds (Pisum sativum L.) of the variety Maxigolt is examined to determine the influence of maturation on the alteration of allergenicity. Different protein extraction methods to get total protein extracts and the protein fractions glutelin, globulin, and albumin from different maturation levels of green pea seeds are applied to SDS-PAGE/silver staining as well as SDS-PAGE/immunoblotting and EAST inhibition experiments using sera of 15 green pea allergic individuals. The SDS-PAGE/silver-staining experiments show the continuous change of protein pattern during maturation. SDS-PAGE/immunoblot and EAST inhibition demonstrate that all levels of green pea seeds show relevant IgE-binding capacity, as do immature seeds. Total IgE-binding capacity rises with the progress of maturation. Although the main allergenic activity is dependent upon the albumin fraction, the glutelin and globulin fractions are also important. The implication of these results is an obvious allergenic potency of all maturation levels, even immature seeds, whereas an increase of allergenicity during maturation could be notched up. The highest allergenic potency is caused by the albumin fraction, but globulin and glutelin fractions also contribute to the allergenicity of green pea.

Adult↗

PubMed2005

[Development of an active robot system for multi-modal paranasal sinus surgery].

BACKGROUND: Severe complications in endoscopic paranasal sinus surgery are rare, however, when they occur they are often fatal. Injuries to the optic nerve or the internal carotid artery mostly occur after penetration of the sphenoid sinus' anterior wall. METHODS: We present the robot system "A 73" with its newly designed 4-canal-microendoscope and special instruments that meets the demands of endoscopic paranasal sinus surgery. A fully automated perforation of the sphenoid sinus' anterior wall was performed in five cadaveric specimens. RESULTS: The sphenoid sinus' anterior wall could be perforated without damaging the surrounding structures in all cases. Subsequently, the approach was enlarged to the desired diameter using telemanipulation mode. The analysis of both the transformation error and intraopertive accuracy showed values in the submillimeter range. CONCLUSIONS: Using a newly developed robotic system, a fully automated perforation of the sphenoid sinus' anterior wall was performed precisely and reproducibly. This approach can be enlarged in a telemanipulation mode.

Cadaver↗

PubMed2005

[Endonasal removal of a large recurrent craniopharyngioma using intraoperative navigation].

In recent years computer-navigation systems have been commonly used in the field of otorhinolaryngology. Taking its limitations and possible failures into account, this technology is considered reasonable and helpful in routine paranasal sinus surgery, particularly in revision cases and complex approaches to the lateral skull base. We report on a patient with a large recurrent craniopharyngioma, and show that the use of intraoperative navigation might even be necessary to accomplish the desired postoperative outcome in certain cases. Future developments will demonstrate whether computer assisted surgery can extend the indications for operative procedures in complex anatomical regions.

Child↗

PubMed2005

Analytical determination of the suitability of different processes for the treatment of odorous waste gas.

In order to determine the efficiency of different treatment systems for the reduction of odorous emissions, a gas chromatographic method followed by simultaneous mass spectrometry and olfactometry (GC-MS/O) was developed. Samples from a coffee bean roasting and a fat and oil processing plant were analyzed, respectively. The results were compared with the data obtained by olfactometric measurements. At a coffee bean roasting plant, cooling gases were analyzed prior to and after treatment in a full scale bioscrubber. The GC-MS/O analysis showed that the amounts of aldehydes and ketones decreased after treatment of cooling gases of coffee bean roasting in the bioscrubber, whereas the contents of the heterocyclic compounds, like pyridine and the pyrazines, and acetophenone and guaiacol remained almost unchanged. The amounts of dimethyl disulfide, 3-hydroxy-2-butanone, and the carboxylic acids increased after bioscrubber treatment. Furthermore, the performance of each stage of a combined experimental plant for the treatment of exhaust air of fat and oil processing was investigated. This treatment plant consisted of a bioscrubber, a biofilter, and an activated carbon adsorber. The important odor-active compounds of the exhaust air of fat and oil processing were the typical fat oxidation products (aldehydes, ketones) and with lower importance 2-pentylfuran, a few terpenes and aromates. Again, the key odor-active compounds, aldehydes and ketones, were degraded in the bioscrubber. Further degradation of aliphatic, unsaturated, methylated, and cyclic alkanes, as well as aromates, terpenes, and furans by the biofilter was observed. After the last treatment stage, the activated carbon filter, only small amounts of aliphatic, unsaturated, methylated, and cyclic alkanes and aromates remained in the waste gas. For both applications, the results of the developed GC-MS/O method correlated very well with olfactometric measurements.

Air Pollution↗

PubMed2004

[Binaural auditory deficit during pregnancy].

Neurological impairment during pregnancy is also commonly found in otorhinolaryngology. Cranial nerve palsy, e.g. of the facial nerve or changes in signal processing of the hearing system, are described. Apart from changes in electrolyte balance, these neurological alterations are attributed to hormone fluctuations. The spontaneous remission of the neurological problems after delivery is frequently reported. This case report presents a 34 year pregnant patient suffering from binaural sensorineural hearing loss and tinnitus in the third trimester. Three weeks after delivery there was a spontaneous remission and a measurable improvement of the audiological findings. Although treatment with cortisone and antibiotics remained without effect, a pharmacological treatment during pregnancy has to be carefully and individually coordinated. An interdisciplinary approach in diagnostic and therapeutic measures together with gynaecologists appears obligatory.

Adult↗

PubMed2004

Migration from can coatings: Part 1. A size-exclusion chromatographic method for the simultaneous determination of overall migration and migrating substances below 1000 Da.

The Council of Europe Resolution on coatings suggests a limit of 10 mg dm-2 for the sum of substances migrating into food simulants from an internal can coating. The Scientific Committee on Food differentiates the migrants into the substances with a molecular weight below 1000 Da, potentially being of toxicological concern, and the less toxicologically relevant species above 1000 Da. Hitherto, the determination of overall migration was based on a gravimetric method. A new method is described for the simultaneous determination of both overall migration and the migration of substances below 1000 Da based on separation by size exclusion chromatography (SEC) followed by ultraviolet detection (UVD) and evaporative light scattering detection (ELSD). The method is suitable for all volatile extraction media and simulants recommended by the European Union. For statistical comparison of both methods, the slightly modified reference method was validated in-house and extended to an additional gravimetric measurement of the migrants below 1000 Da. For the determination of the overall migration, both methods provided similar reproducibility (validated gravimetry: standard deviation (SD) = 0.16 mg dm-2; SEC-ELSD/UVD: SD = 0.12 mg dm-2) but significantly better results were obtained by the SEC-ELSD/UVD method. For migrating substances below 1000 Da, the gravimetric determination provides a poor sensitivity (limit of detection = 0.35 mg dm-2) compared with the SEC-ELSD/UVD method (limit of detection = 0.04 mg dm-2). The new method offers a lower limit of detection and higher precision as well as being less time consuming and easier to use.

Chromatography↗

PubMed2003

Migration of lubricants from food packagings. Screening for lipid classes and quantitative estimation using normal-phase liquid chromatographic separation with evaporative light scattering detection.

A normal-phase high-performance liquid chromatography (NP-HPLC) method is introduced for the identification and quantitative estimation of 12 lipid classes (paraffin, wax esters, cholesterol esters, fatty acid methyl esters, triacyl glycerols, fatty alcohols, free fatty acids, cholesterol, 1,3-diacyl glycerols, 1,2-diacyl glycerols, monoacyl glycerols and fatty acid amide) used as lubricantsin food packaging materials. The HPLC separation is carried out on a LiChrospher Diol (100 A, 5 microm, 125 mm x 3 mm) column with gradient elution (isooctane/0.1% acetic acid in tert-butyl methyl ether) and evaporative light scattering detection (ELSD). The method has been calibrated with representatives of each class in working ranges of about 5-150 mg/l, depending on the lipid class. Intra-day variance for all representatives range from 1.9 to 5.1%, inter-day variances from 7.0 to 26.5% and the limits of detection from 0.79 to 3.65 mg/l (except for two classes). A simple sample preparation could be established for the determination of migrating lubricants obtained from packaging materials containing external or internal lubricants. Since the detector response depends on the chain length and the degree of saturation, the quantification of a lipid class with unknown composition is only semi-quantitative. The amount of migrating lubricants from an epoxy-based can coating could be estimated with 0.3 mg/dm2 and from a light weight container with 5.5 mg/dm2.

Chromatography, High Pressure Liquid↗

PubMed2003

Trans fatty acids (TFA): analysis, occurrence, intake and clinical relevance.

More than one quarter of total daily calories are normally provided by fatty acids which contain at least one double bond. The usual configuration of these double bonds is the cis configuration. Trans fatty acids (TFA) are formed in technological and microbiological processes by isomerization of cis double bonds to trans double bonds. In the 1990s, there was public health concern about epidemiological studies suggesting that TFA increase the risk of coronary heart disease. High intakes of TFA may have an influence on total cholesterol and other blood parameters; but on the other hand there have been a lot of studies which have not been able to confirm these results. TFA are formed in varying amounts during the industrial hydrogenation of vegetable oils and in the first stomach of ruminants. Regular margarines contain varying contents of partially hydrogenated vegetable oils, and therefore of TFA. The main dietary TFA are the trans octadecenoic acids, which contribute to approximately 80-90 % of total TFA content in foods. The predominant isomer of milk fat is trans vaccenic acid, which is directly influenced by ruminant feeding conditions. For a reliable identification and quantification of TFA in foods and other biological matrices it is necessary to use a combination of chromatographic methods (GC-FID, GC-MS, GC-FTIR, Ag superset +-HPLC).

Coronary Disease↗

PubMed2003

Identification and analysis of conjugated linoleic acid isomers (CLA).

CLA are predominantly found in milk, milk products, meat and meat products of ruminants. The distribution of CLA isomers in cheese and/or meat shows one major isomer C18:2 c9t11 with nearly 84% of total CLA. It is estimated that the daily intake of CLA using the German Nutrition Study is 0.35 g/d for women and 0.43 g/d for men.

Animals↗

PubMed2003

[Facial nerve schwannoma in the inner auditory canal and geniculate ganglion].

BACKGROUND: Schwannoma of the vestibular nerve is the most common tumor found in the inner auditory canal. If a schwannoma of the facial nerve is found unexpectedly during surgery, the original surgical plan may have to be changed. In our series, we describe the symptoms, diagnostic procedures and therapy of this infrequent, benign tumor. In particular, we want to analyse the influence of diagnostic techniques, such as magnetic resonance tomography and electrophysiology, on the diagnosis of these tumors. PATIENTS: Between 1975 and 2001, we diagnosed 17 cases of facial nerve schwannoma in the inner auditory canal or the geniculate ganglion. All patients were treated surgically. In 16 cases, we used the enlarged middle fossa approach and in the remaining patient the translabyrinthine approach was used. RESULTS: In 11 cases, the facial nerve could be saved but in six the nerve had to be rebuilt with a transplant. During the first years of our study, palsy of the facial nerve was a frequent finding. In the later years, a hearing impairment and tinnitus became the most frequent symptoms. CONCLUSIONS: Advances in magnetic resonance imaging have, in many cases, facilitated the differentiation between schwannomas of the facial nerve and the vestibular nerve over the last years. Signal enhancement at the geniculate ganglion is important for the diagnosis of facial nerve schwannoma. In individual cases, we found significant findings using electrophysiological procedures. In three cases, the temporal delay was elongated. Based on these findings, the therapeutic procedures can be discussed together with the patients.

Adolescent↗

PubMed2003

[Advanced transfacial approach to extensive sellar adenoma of the pituitary gland].

The excision of tumors of the pituitary gland is usually achieved via a transsphenoidal transnasal approach. In the past, alternative approaches were described for macroadenomas. Especially in tumors surrounding the internal carotid artery (ICA) and the optic nerve, the selection of the appropriate approach is of importance. We demonstrate the case of a second extensive relapse of a macroadenoma after primary transsphenoidal resection and radiation therapy. As the tumor enclosed both the ICA and left optic nerve, a median external approach via the upper midface was chosen. After the median skin incision and translocation of the upper parts of the nasal structure, the papyraceous lamina was removed bilaterally. The orbital tissue was laterally exposed with retractors, achieving a wide access to both carotids and optic nerves. The functional and aesthetic results were satisfactory. Compared with other approaches, this one provides a good exposure of both the ICA and optic nerve.

Adenoma↗

PubMed2003

[Surgical therapy of Madelung's disease in the head and neck area].

PATIENTS AND METHODS: Between 1995 and 2001 we treated 12 patients with benign symmetric lipomatosis in the head and neck. The group comprised 11 men and 1 woman aged 34-62 (M=47). The most frequent complaints were diminished range of motion of the head and obstruction when eating or speaking. Combined lipectomy and liposuction were performed in all patients, with liposuction being carried out in a second session. RESULTS: The mean follow-up period was 3 years. The functional results were very satisfactory in all patients. Of the 12 patients, 9 were also satisfied with the aesthetic outcome.A recurrence occurred in three patients 1.5, 2, or 3 years after the operation. Severe complications were not observed. CONCLUSIONS: According to our experience, combined lipectomy and liposuction represents a successful procedure in treating benign symmetric lipomatosis in the head and neck region.Nevertheless, advantages and drawbacks of the two techniques should be equally considered prior to surgery.

Adult↗

PubMed2003

Dependence of tocopherol stability on different cooking procedures of food.

The influence of the kind of treatment during the preparation of hot meals (roasting, baking, stewing) on the stability of the tocopherols, which were added to the food through the margarines used, were examined in different food matrices. All preparation methods resulted in a loss of tocopherols. They could be divided into a group of only small loss of tocopherols (lower than 20%) and into a second group with nearly 70% loss of tocopherols (roasting of meat, steaming of peas). In the first group losses of tocopherols were directly associated with the fatty acid patterns of the used margarines, especially with the share of polyunsaturated fatty acids. On the other hand, during the roasting of meat nearly 70% of the tocopherols were destroyed by direct oxidation without a prohibitive effect on the lipid oxidation. The extreme high loss of tocopherols during the steaming of peas may be caused by the catalytic effect of the metal surface of the used pot. There were no losses of tocopherols observed when the experiments were repeated under identical conditions in an inert glass pot. Only tocopherol losses during baking may have a nutritional importance because of the great fat amount which are taken in with cookies.

Animals↗

PubMed2003

[Growth of sporadic vestibular schwannomas correlates with Ki-67 proliferation index].

BACKGROUND: Sporadic vestibular schwannoma show a wide variability of their growth rate. Some tumors might remain quiescent for a long time without symptoms and other tumors might suddenly enlarge. Sometimes during surgical removal of tumors, it is useful to have a parameter for the prediction of the further growth potential of the schwannoma, especially if tumor resection results in functional impairment of the facial nerve. An often used histological parameter for growth rate of tumor cells is the proliferation index. METHODS AND PATIENTS: In our study we observed a series of 50 patients with neurinoma of the vestibular nerve by "wait and scan". After the first magnetic resonance imaging (MRI) all patients were controlled by a second MRI. The time between the MRIs ranged between 3 and 26 months (median 9). In 45 of 50 patients a surgical removal of the tumor by transtemporal approach followed. RESULTS: The proliferation index (Ki-67) was identified in the histological tumor specimens. The next step was the correlation of proliferation index and "tumor doubling time" (TDT). The volume of the tumors was provided by measuring three diameters of the tumors in MRI and calculating the volume with a formula. The volume of the tumors were used to calculate tumor growth and TDT. 10 patients showed no tumor growth during follow up. The average TDT in 40 cases was 22 months (SD 16). In 33 cases we were able to determine a proliferation index, which showed an average score of 1.99 %. Statistical analysis showed a correlation between proliferation index and TDT with a coefficient of - 0.42 (s: 0.014). In two cases with relevant clinical tumor growth (TDT: 12 months), the MIB-1 index was nearly 0 % in different areas of the tumor specimen. May be in these cases, the cell proliferation declined just before operation. On the other hand we found one patient with a high proliferation index of 3.3 % and a rather long TDT of 19 months. CONCLUSIONS: The determination of proliferation can serve as a further decision guidance during surgery of vestibular schwannoma.

Cell Division↗

PubMed2002

Thin section arrays for I-FISH analysis of chromosome-specific imbalances in squamous cell carcinomas of the head and neck.

Thin section arrays of 20 head and neck squamous cell carcinomas were studied by I-FISH for gains (including amplification) and losses of specific genomic segments. These arrays allow the examination not only of a number of tumor sections but also of the surrounding margins and of inconspicuous control tissue in one experiment. All tumor sections examined significantly differed from the inconspicuous control tissues by containing more or less extensive cell populations with aberrant signal constitutions. In no case, however, did the aberrant population constitute the whole area of the section. Gains of signals were strikingly more frequent than were losses. All tumors showed significant gains of the segments examined, the highest differences between tumor and control sections were found for the segments 9q34 and 8q24, followed by 5p15.3 and 11q13. Amplifications were most frequently found of 11q13: 8 of the 20 tumors showed amplifications in more than 20% of the nuclei, while no nucleus with more than four signals was found in any of the control tissues (control: 0%). Amplifications of the target sequences on chromosomes 8 (14 tumors) and 9 (8 tumors) were observed in low but significant percentages of nuclei, no significant cell population was detected with an amplification of 5p15.3. Fourteen tumors exhibited a significant loss of 13q14, and only 8 tumors a significant loss at any other site. In the tumor margin sections, in most cases, the margins apparently were also affected by the one or the other of the genomic changes of the pertinent primary tumor. Nevertheless, there were, in some cases, also large differences depending on the way of analysis, but also on the specific signal constitution considered. Tumor stages T3 and T4 tended to have higher frequency of nuclei with gains of 5p15.3, 8q24, and 11q13 as compared to T2 tumors and less gains of 9q34 and loss of 13q14. With the exception of 8q24 and 13q14 alterations there was also a trend to higher percentages of aberrant nuclei in the margin of T3-4 tumors vs. T2 tumors.

Aged↗

PubMed2001

A permanent fish cell line (EPC) for genotoxicity testing of marine sediments with the comet assay.

Genotoxicity and cytotoxicity were evaluated in an in vitro system with a permanent cell line Epithelioma papulosum cyprini (EPC) derived from a skin tumour of carp (Cyprinus carpio L.). EPC cells were exposed to different concentrations of organic sediment extracts from the North Sea for 24h. After incubation the cells were analysed for viability and DNA strand breaks with the comet assay or single cell gel electrophoresis (SCGE). The results confirm the sensitivity of this assay. Out of 10 marine sediment samples from the North Sea, 9 showed a dose-dependent genotoxic effect. The EC(50) of sediment extracts ranged from 7 to 307 mg sediment dry weight/ml assay volume. Hepatic microsomal enzymes from dab (Limanda limanda L.) was proposed for enzymatic activation of benzo[a]pyrene (BAP) or sediment extracts, respectively. The suitability of this in vitro test system for assessing genotoxic and cytotoxic effects of marine sediment extracts on EPC cells could be demonstrated.

Animals↗