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Biomedical subjects

W Jassem

Publications and source records attributed to W Jassem.

13 recordsLinked to original sources
PubMed1997

Influence of structure on the antioxidant activity of indolinic nitroxide radicals.

An in vitro study was carried out to verify whether the chain length of a substituent on an indolinic nitroxide could influence its antioxidant activity in different biological environments subjected to oxidative stress. Three distinct indolinic nitroxides were synthesized and compared with vitamin E and Trolox (a hydrophilic analogue of vitamin E), where the only difference between the nitroxides was the length of the hydrocarbon chain in the 2-position of indole, namely 2 (C2), 10 (C10), and 18 (C18) carbons. All the nitroxides were effective in preventing oxidation of bovine serum albumin, but to different extents, with the longer chain derivatives being more efficient. However, the C2 compound was the most efficient in preventing lipid peroxidation in microsomal membranes. The C2 and C18 compounds, Trolox, and vitamin E protected microsomal protein oxidation to the same extent at the highest concentration used (13 microM). The nitroxide with a C10 chain was less effective in this system. The influence of these compounds on the enzymatic activity of two mitochondrial proteins subjected to oxidative stress was also studied by means of oxygraph measurements. Mitochondrial rotenone-sensitive NADH oxidase and succinate oxidase responded differently to BuOOH-induced radical chemistry, and the compounds under study also protected the activity of the two enzymes but to different extents. The results clearly demonstrate that indolinic nitroxides are very efficient antioxidants, protecting both lipids and proteins from peroxidation. The indole structure influences the antioxidant efficacy in biological systems.

Animals↗
PubMed1996

Glyoxalase II and glutathione levels in rat liver mitochondria during cold storage in Euro-Collins and University of Wisconsin solutions.

Glutathione and glyoxalase II levels were evaluated in cytosolic and mitochondrial compartments of rat liver after 7 and 24 hr of cold storage in University of Wisconsin (UW) and Euro-Collins solutions. 1-4 A similar time-dependent depletion of cytosolic glutathione up to about 60% of control values was observed in both Euro-Collins and UW solutions. Cytosolic glyoxalase II showed activity oscillations in livers stored in Euro-Collins but not in UW. Mitochondrial glutathione and glyoxalase II were severely depleted soon after 7 hr of cold storage in Euro-Collins, whereas the same parameters did not change in liver stored in UW after 24 hr. UW is confirmed to be the most suitable solution for liver cold storage and we conclude that mitochondrial glutathione and glyoxalase II can be important parameters in assessing mitochondrial and cell function.

Adenosine↗
PubMed1987

Classification of basic fundamental frequency patterns using discriminant functions.

An attempt was made to see whether realizations of eight different pitch patterns can be classified automatically by subjecting fundamental frequency curves to statistical treatment using two kinds of discriminant functions. The materials consisted of 150 imitations of each of the eight prototypes (eight intonations of a short Polish phrase). Approximately 80% of the time the statistical procedures assigned the individual tokens to the appropriate classes. Most of the misassignments were due to wrong imitations. The discriminant functions also indicated similarities and dissimilarities among the pitch patterns. It is suggested that perceptually and linguistically, some differences between pitch patterns may not be quite categorical.

Algorithms↗
PubMed1975

Arytenoid vocal shunt in laryngectomized patients.

A method is presented for forming short, mucosa-lined vocal shunt in cases of supracricoid laryngectomy with preservation of one or two arytenoids, or the interarytenoid fold alone. On the basis of radiologic and particularly radiocinematographic examinationion of the anterior pharyngeal wall is of paramount importance. In cases of complete absence of leakage, said wall lies in the plane of the arytenoids or somewhat posteriorly. After simple supracricoid laryngectomy it is possible to prevent aspiration also by translocation of the anterior pharyngeal wall into the plane of the cricoid cartilage plate. The clinical experience with this supracricoid shunt is still scanty. Of 25 cases with the arytenoid vocal shunt, phonation was possible in 22 cases under the expiratory pressure of 20-45 cm H2O; in one under the more elevated pressure, and in the last two the result is still not known. Loudness of speech was 70-100 db and its comprehensibility 73-90 percent. Complete absence of leakage was observed in 17 cases, "practical" prevention of aspiration (some drops of thin fluids, no saliva) in seven cases, profuse leakage in one case (ceased after correction), In the last 10 consecutive cases the problem of aspiration was completely eliminated. Advantages and disadvantages of our own method in comparison with Asai's method have been presented.

Deglutition↗
PubMedDate not supplied

Identification and discrimination of speech sounds in monosyllabic meaningful words and nonsense words by children.

297 children aged 9-14 with normal hearing and intelligence level were examined by speech audiometry. Ten lists with monosyllabic meaningful and nonsense words were used. All the lists were phonemically and structurally balanced in the same way and were applied with an intensity level varying between 26 dB and 61 dB. The identification and discrimination scores for Polish speech sounds were calculated from written-response sheets. The identification scores were generally significantly lower for nonsense words, and up to a certain extent, increased with age. An examination of the discrimination scores showed that confusions were related to the distinctive features of the phonemes. The results represent the first stage of a project on speech sound identification in children and may have practical implications for the rehabilitation of children with hearing loss.

Adolescent↗
PubMedDate not supplied

Speech audiometry for children and subjective probability of Polish words.

Word lists used for speech audiometry should fulfill a number of conditions in order that the results of hearing tests be unambiguous and directly interpretable not only in terms of possible hearing loss but also in terms of the neurolinguistic decoding process. In order to construct a proper word list, it was decided to attempt to estimate the subjective probability of word occurrence in schoolchildren. Nine different lists of over 300 words each were prepared, containing words of all assumed degrees of familiarity. In the preliminary stage, the lists were presented to 600 children in primary and secondary schools. The children were asked to mark each word with a number indicating their relative familiarity with the word. The answers were examined for homogeneity.

Audiometry↗