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Biomedical subjects

A Netzer

Publications and source records attributed to A Netzer.

29 records · Page 2Linked to original sources
PubMed1975

Chlorination in dilute aqueous systems; 2,4,6-trichlorophenol.

Chlorination of wastewaters can cause extensive transformations of organic contaminants. In the case of phenol, the reaction path is only partially understood. In an effort to elucidate this reaction, 2,4,6-trichlorophenol in dilute aqueous solution was treated with excess hypochlorous acid at pH 3.5-6. The major products were 2,6-dichloroquinone and 2,4,4,6-tetrachloro-2,5-cyclohexadienone. Additional polychlorinated species are formed in minor amounts by the addition of chlorine and/or hypochlorous acid to the aromatic ring.

Chlorine↗
PubMedDate not supplied

Oral magnesium intake reduces permanent hearing loss induced by noise exposure.

INTRODUCTION: Following animal experiments where correlations were observed between serum magnesium level and noise-induced permanent hearing threshold shifts (NIPTS), we tested the prophylactic effect of magnesium in human subjects exposed to hazardous noise. METHODS: Subjects were 300 young, healthy, and normal-hearing recruits who underwent 2 months of basic military training. This training necessarily included repeated exposures to high levels of impulse noises while using ear plugs. During this placebo-controlled, double-blind study, each subject received daily an additional drink containing either 6.7 mmol (167 mg) magnesium aspartate or a similar quantity of placebo (Na-aspartate). RESULTS: NIPTS was significantly more frequent and more severe in the placebo group than in the magnesium group, especially in bilateral damages. NIPTS was negatively correlated to the magnesium content of blood red cells but especially to the magnesium mononuclear cells. Long-term additional intake of a small dose of oral magnesium was not accompanied by any notable side effect. CONCLUSION: This study may introduce a significant natural agent for the reduction of hearing damages in noise-exposed population.

Administration, Oral↗
PubMedDate not supplied

The effects of noise on the vestibular system.

PURPOSE: Subjects with noise-induced hearing loss sometimes also complain about balance disorders, but reports of clinical series that give contradictory results are highly controversial. This study was designed to evaluate the effects of intense noise on the vestibular labyrinth, both in subjects with symmetrical hearing loss and in subjects with asymmetrical loss, and to examine the correlation between the subjects' complaints and the results of the vestibular function tests. METHODS: A total of 258 male military personnel, heavily exposed to various intense noises, were included in the study. They were divided into 2 groups according to their hearing; 134 had a symmetrical high-tone hearing loss, and 124 had asymmetrical losses. Each group was divided into 2 subgroups according to the presence or absence of vestibular complaints. All of the subjects underwent a complete audiological and electronystagmographic evaluation. RESULTS: We found that vestibular damage caused by intense noise exposure might be expressed clinically in subjects with asymmetrical hearing loss. There was a strong correlation between the subjects' complaints and the results of the vestibular function tests. There was no correlation between the severity of the hearing loss and the vestibular symptomatology and pathology. CONCLUSIONS: Subjects exposed to intense noise may have evidence of vestibular pathology only when there is an asymmetrical hearing loss. Whenever hearing loss is symmetrical, an equal damage to the vestibular system of both ears is most probably responsible for the absence of abnormal findings on the vestibular function tests. The results of this study have important medicolegal implications for individuals exposed to intense noises.

Adult↗
PubMedDate not supplied

Epstein-Barr virus and cancers of the head and neck.

Denis Burkitt pioneered the association of viruses and cancer in humans with his observations of lymphomatous tumors in children in equatorial Africa. The Epstein-Barr virus (EBV), a human B lymphotrophic herpes virus, is strongly associated with undifferentiated carcinoma of the nasopharynx and African-type Burkitt's lymphoma. More recently, an association of this virus with other epithelial neoplasms, lymphomas, and immunodeficiency-related malignant and nonmalignant conditions has been reported. Since many of these tumors are rare, much of the information is based on sporadic reports and relatively small series of patients. The purpose of this report is to review the literature and examine the growing association of EBV with various head and neck malignancies.

Antibodies, Viral↗
PubMedDate not supplied

Synergistic necrotizing cellulitis as a complication of peritonsillar abscess.

Peritonsillar abscess, a complication of tonsillitis, is not uncommon. The usual treatment consists of needle aspiration or surgical drainage and antibiotic treatment. Tonsillectomy may be used in the management of this condition, either at the time of diagnosis or after an interval period. Severe complications of peritonsillar abscess are rare. Synergistic necrotizing cellulitis is a fulminant infection associated with spread along fascial plains, necrosis of connective tissue and muscle, and high mortality. It is usually otondogenic in origin in the cervicofacial area and occurs in debilitated or immune compromised patients. We discuss cervicofacial-necrotizing soft tissue disease and report an unusual case of extensive synergistic necrotizing cellulitis of the neck, chest, and shoulder as a result of a peritonsillar abscess.

Cellulitis↗
PubMedDate not supplied

The association between iron-deficiency anemia and recurrent acute otitis media.

PURPOSE: This study was designed to examine the association between iron-deficiency anemia and the frequency of recurrent acute otitis media in children, and to evaluate the effect of restoring normal hemoglobin levels on the frequency of acute otitis media attacks. MATERIALS AND METHODS: A total of 680 children with frequent episodes of acute otitis media were enrolled in the study. The levels of the hemoglobin were measured in both these children and in 200 healthy children with no history of infections. The correlation between hemoglobin level and the frequency of middle ear infections was studied and analyzed. All children with hemoglobin levels lower than 9.5 g/dL received iron supplementation until they reached a level of at least 11 g/dL, and the subsequent frequency of middle ear infections was recorded. RESULTS: The 680 children had an average of 8.3 +/- 2.7 episodes of acute otitis media per year per child, and an average hemoglobin level of 11.4 +/- 2.7 g/dL, whereas the controls had an average hemoglobin level of 13.1 +/- 2.5 g/dL. Twenty percent had hemoglobin levels below 9.5 g/dL. These children had more episodes of acute otitis media when compared with children with average levels. By increasing the hemoglobin level in these children, the frequency of the episodes of acute otitis media decreased significantly. CONCLUSIONS: This study confirms that anemic children have higher prevalence of episodes of acute otitis media in comparison to healthy, nonanemic children, and shows that there is a direct relationship between the degree of the anemia and the number of the episodes.

Acute Disease↗
PubMedDate not supplied

Selective release of apical membrane enzymes from cultured renal epithelia by phosphatidylinositol-specific phospholipase C.

Membrane proteins can be attached to the plasma membrane in several ways. Recently, a mechanism has been described, by which a number of cell surface proteins are anchored to the exoplasmic side of the plasma membrane by covalent linkage to glycosyl-phosphatidylinositol (GPI). The growth properties of renal epithelial cells in tissue culture enable free access to apical cell surface and brush border membrane proteins. To study the nature of membrane anchoring of apical plasma membrane enzymes in cultured renal epithelial cells, confluent LLC-PK1, OK, NRK, and MDCK epithelia were treated in tissue culture dishes with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC), and the PI-PLC-specific release into the tissue culture medium of the apical membrane enzymes alkaline phosphatase (AP), gamma-glutamyl transpeptidase, leucine aminopeptidase, trehalase, and maltase was determined. Of the five enzymes tested, AP and trehalase, already described as GPI-anchored membrane proteins, were specifically released by PI-PLC from intact cell monolayers. Of the four cell lines investigated, LLC-PK1 cells express AP and trehalase which were released by PI-PLC. In OK cells, which lack AP activity, only trehalase was found to have PI-PLC-releaseable enzyme activity. MDCK cells, on the other hand, express AP activity, releaseable by PI-PLC, but no trehalase activity. In studies on the time course of synthesis and reinsertion of AP into the apical membrane of LLC-PK1 cells after removal by PI-PLC, a 60% recovery of AP activity was obtained only after 7 days. Analysis of protein release by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of culture supernatants after surface labeling with biotin and subsequent Western blotting with streptavidin revealed four protein bands at approximately 130, 90, 30, and 20 kD in LLC-PK1 cells and five GPI-anchored proteins at 110, 85, 65, 40, and 26 kD in OK cultures. The finding of a PI-PLC-specific release of apical membrane enzymes from renal tubular cell lines of different species (pig, opossum, rat, and dog) and of different nephron origin indicates a high conservation of the GPI anchor of renal brush border membrane proteins and further proves the high degree of differentiation retained by the cell lines in tissue culture. In addition, this method may provide a possible tool for isolating GPI-anchored apical membrane proteins from intact epithelial monolayer cultures.

Animals↗