Otoacoustic emissions as a screening test for hearing impairment in children recovering from acute bacterial meningitis

OBJECTIVES: To study the efficacy of otoacoustic emissions (OAEs) as a screening test for hearing impairment in children with acute bacterial meningitis. Hearing tests were performed before discharge from the hospital in an attempt to improve coverage and avoid delays in the diagnosis of postmeningitic hearing loss. METHODS: Children with bacterial meningitis were recruited from 21 centers. In the 48 hours before discharge from the hospital, all patients underwent a thorough audiologic assessment consisting of transient evoked OAEs, auditory brainstem responses (ABRs), otoscopy, and tympanometry. Hearing loss was defined as ABR threshold >/=30 dB. The results of OAE screening were compared with the gold standard of ABR threshold. RESULTS: Of 124 children recruited, we were able to perform both OAEs and ABRs on 110 children. Seven (6.3%) of the 110 children had ABR threshold >/=30 dB; 2 had sensorineural hearing loss and 5 had conductive hearing loss. At follow-up, hearing loss persisted in both cases of sensorineural hearing loss and no new cases were identified. All 7 children with hearing loss failed the OAE screening test. Ninety-four children with normal hearing thresholds passed the test, and 9 failed. Thus, the screening test had a sensitivity of 1.00 (95% confidence interval, 0.59 to 1.00), a specificity of 0.91 (0.85 to 0.97), a positive predictive value of 0. 44 (0.20 to 0.70), and a negative predictive value of 1.00 (0.96 to 1.00). CONCLUSIONS: OAE screening in children recovering from meningitis was found to be feasible and effective. The test was highly sensitive and reasonably specific. Inpatient OAE screening should allow early diagnosis of postmeningitic hearing loss and prompt auditory rehabilitation.     

Iron-induced oxidative DNA damage and its repair in primary rat hepatocyte culture

Iron-overload diseases frequently develop hepatocellular carcinoma. The genotoxic mechanism whereby iron is involved in hepatocarcinogenesis might involve an oxidative process via the intermediate production of reactive oxygen species. This was presently investigated by examining kinetics of formation and repair of DNA base lesions in primary rat hepatocyte cultures supplemented with the iron chelate, ferric nitrilotriacetate Fe-NTA (10 and 100 microM). Seven DNA base oxidation products have been identified in DNA extracts by gas chromatography- mass spectrometry, which showed a predominance of oxidized-purines (8- oxo-guanine, xanthine, fapy-adenine, 2-oxo-adenine) above oxidized pyrimidines (5-OHMe-uracil, 5-OH-uracil, 5-OH-cytosine) in control cultures. All these DNA oxidation products revealed a significant dose- dependent increase at 4 to 48 h after Fe-NTA supplementation, among which fapy-adenine showed the highest increase and 5-OH-cytosine was the least prominent. Involvement of iron in this oxidative process was established by a correlation between extent in DNA oxidation and intracellular level of toxic low molecular weight iron. DNA excision- repair activity was estimated by release of DNA oxidation products in culture medium. All the seven DNA oxidation products were detected in the medium of control cultures and showed basal repair activity. This DNA repair activity was increased in a time- and dose-dependent fashion with Fe-NTA. Oxidized-pyrimidines, among which was 5-OHMe-Uracil, were preferentially repaired, which explains the low levels detected in oxidized DNA. Since oxidized bases substantially differed from one another in terms of excision rates from cellular DNA, specific excision- repair enzymes might be involved. Our findings, however, demonstrate that even though DNA repair pathways were activated in iron-loaded hepatocyte cultures, these processes were not stimulated enough to prevent an accumulation of highly mutagenic DNA oxidative products in genomic DNA. The resulting genotoxic effect of Fe-NTA might be relevant in understanding the hepatocarcinogenic evolution of iron-overload diseases.      

Surgical correction of incomplete form of open atrioventricular canal in adults

Clinical and anatomo-hemodynamic features of adult patients with incomplete form of the open atrioventricular canal are presented, policy of surgical treatment and optimal degree of surgical intervention on mitral valve are determined. The study of variant anatomy of the defect, revealed two variants of left atrioventricular valve formation (with "functional" and with "anatomical" septal commissure). In the first anatomic variant the mitral insufficiency was hemodynamically important and required surgical correction. In the second variant, the mitral valve had good closure function, that permitted to avoid the routine suturing of anterior velum's splitting.     

Molecular bases of vaccine-prevention of plague

The molecular mechanisms of pathogenicity and properties of the formation of specific plague immunity are reviewed. The history and modern state of vaccine-prevention of plague are described. Special attention is focused on the prospects in the plague vaccine development, and possible approaches to the improvement of vaccine preparations are considered.     

Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study

BACKGROUNDToday, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads.AIMTo compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits.METHODSThe study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet''s Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred.RESULTSThe breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly (P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM (P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 (P = 0.001).CONCLUSIONTANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration (P = 0.001) in healthy and in osteoporotic bone.     

Contribution of Cyanotoxins to the Ecotoxicological Role of Lichens

The fascinating world of lichens draws the attention of the researchers because of the numerous properties of lichens used traditionally and, in modern times, as a raw material for medicines and in the perfumery industry, for food and spices, for fodder, as dyes, and for other various purposes all over the world. However, lichens being widespread symbiotic entities between fungi and photosynthetic partners may acquire toxic features due to either the fungi, algae, or cyano-procaryotes producing toxins. By this way, several common lichens acquire toxic features. In this survey, recent data about the ecology, phytogenetics, and biology of some lichens with respect to the associated toxin-producing cyanoprokaryotes in different habitats around the world are discussed. Special attention is paid to the common toxins, called microcystin and nodularin, produced mainly by the Nostoc species. The effective application of a series of modern research methods to approach the issue of lichen toxicity as contributed by the cyanophotobiont partner is emphasized.