Hyperbaric oxygen therapy in treatment of sudden sensorineural hearing loss: finding for the maximal therapeutic benefit of different applied pressures.

We compared the efficacy of hyperbaric oxygen (HBO2) therapy used in the treatment of sudden sensorineural hearing loss (SSNHL) as a supplementary therapy to the first-line medical treatment according to the different applied pressures used in HBO2 treatment while maintaining the same number of sessions, periodicity and exposure times. We evaluated data from 115 patients suffering from SSNHL within seven days of hearing loss: 35 patients received the standard treatment protocol (control group), and 80 individuals were treated with additional application of HBO2 therapy pressured to 2.0 ATA (H2.0; n=49) or 2.5 ATA (H2.5; n=31), respectively. Treatment success was assessed using pre- and post-treatment audiograms. We found significant differences in both HBO2 groups compared to the control group. In low frequencies the most significant differences can be seen in both H2.0 and H2.5. In spoken speech frequencies only the H2.0 group was statistically significant. In high frequencies the therapeutic benefits were the lowest. Furthermore, we found a notable difference in the therapeutic effect of HBO2 therapy according to the different applied pressure. At low frequencies, the use of 2.5 ATA pressure was more efficient. However, in the higher frequency ranges, the better hearing gains were obtained at the 2.0 ATA pressure. Our results support the possibility of optimizing treatments individually, depending on the type and frequency range of hearing impairment (shape of the audiogram) in favor of using the 2.0 ATA. This is important in terms of an individual approach to each patient as well as to minimize the burden of a patient in order to obtain the maximum therapeutic effect.

Efficacy of hyperbaric oxygen therapy as a supplementary therapy of sudden sensorineural hearing loss in the Slovak Republic.

We evaluated the efficacy of hyperbaric oxygen (HBO2) therapy used as a supplement to the first-line medical treatment of sudden sensorineural hearing loss (SSNHL). We tested 68 patients suffering from SSNHL within seven days of hearing loss: 21 patients received the standard treatment protocol of our department (control group) and 47 individuals were treated with an additional application of HBO2 therapy. Treatment success was assessed using pre- and post-treatment audiograms. Outcomes of our study showed a statistically significant improvement in auditory threshold in all frequency groups for the HBO2 group (P ⟨ 0.001), whereas in the control group the statistically significant mean auditory gain was observed only for the frequency zone 1,000 to 2,000 Hertz (P = 0.01). Furthermore, the rate of hearing gain in the HBO2 group was more than doubled (61.7%) compared to the control group (28.6%). Complete recovery of the hearing gain in the control group was observed only in the first two frequency groups (14.29%; 4.76%; 0.00%), whereas in the HBO2 group complete recovery was seen in all the frequency groups (19.15%; 21.13%; 6.38%) as well as in the whole frequency range (6.38%). The efficiency of both treatment protocols was statistically significant (P ⟨ 0.001) in both groups of patients, but supplementation of the therapy with HBO2 demonstrated a statistically significantly increase in the effect of pharmacotherapy (P ⟨ 0.001) by 11.5 decibels (dB) up to the final hearing gain of 20 dB. HBO2 is therefore a promising modality of SSNHL treatment, but specific mechanisms of HBO2 in patients with SSNHL are still unknown. Further investigations are warranted to explore the mechanisms of action.

Enriching the drinking water of rats with extracts of Salvia officinalis and Thymus vulgaris increases their resistance to oxidative stress.

Nature is an attractive source of therapeutic compounds. In comparison to the artificial drugs, natural compounds cause less adverse side effects and are suitable for current molecularly oriented approaches to drug development and their mutual combining. Medicinal plants represent one of the most available remedy against various diseases. Proper examples are Salvia officinalis L. and Thymus vulgaris L. which are known aromatic medicinal plants. They are very popular and frequently used in many countries. The molecular mechanism of their biological activity has not yet been fully understood. The aim of this study was to ascertain if liver cells of experimental animals drinking extracts of sage or thyme will manifest increased resistance against oxidative stress. Adult Sprague-Dawley rats were divided into seven groups. They drank sage or thyme extracts for 2 weeks. At the end of the drinking period, blood samples were collected for determination of liver biochemical parameters and hepatocytes were isolated to analyze (i) oxidatively generated DNA damage (conventional and modified comet assay), (ii) activities of antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx)] and (iii) content of glutathione. Intake of sage and thyme had no effect either on the basal level of DNA damage or on the activity of SOD in rat hepatocytes and did not change the biochemical parameters of blood plasma. Simultaneously, the activity of GPx was significantly increased and the level of DNA damage induced by oxidants was decreased. Moreover, sage extract was able to start up the antioxidant protection expressed by increased content of glutathione. Our results indicate that the consumption of S.officinalis and T.vulgaris extracts positively affects resistency of rat liver cells against oxidative stress and may have hepatoprotective potential.

Study of urinary concentrations of mandelic acid in employees exposed to styrene.

Mandelic acid (MA) is an important metabolite of styrene. In humans, measurement of its concentration in urine provides an important assessment of the overall level of styrene exposure in workers of the reinforced plastic manufacturing industry. The aim of our study was to investigate in these workers the relationship between MA concentration and styrene exposure time and intensity as well as its dependence on work occupation. The concentration of MA in the urine samples of 35 employees was analyzed with HPLC (high performance liquid chromatography). Out of 35 workers, 11 performed laminating, 11 milling and finalizing, 6 laying-up and spraying-up, and 7 worked in background support. Urinal samples were obtained twice a day over the course of three weeks, at the beginning and the end of the work shift. We found a significant increase in MA concentrations during a work shift in all tested days (Wilcoxon test p < 0.05). Employees working in elevated atmospheric concentrations of styrene (93.77-159.88 mg/m3) had significantly higher MA concentrations in urine compared to other groups at both the beginning and the end of the shift (Kruskal Wallis test p < 0.001) (p < 0.001). Only samples from laminating workers exceeded the biological limit of MA concentration (640 mg/L) at the end of the shift. Normalisation of MA concentration to body mass index (BMI, normal range: 21.7 +/- 3.2 kg/m2) refined differences within groups (Kruskal-Wallis analysis p < 0.001). The accumulation of MA at the end of the work shift for measured time period was not significant for the measured time period (Friedman analysis p > 0.11). Our results confirmed that MA is a sensitive metabolic marker of styrene exposure without cumulative effect. However, normalization of MA concentrations to BMI can improve the accuracy of styrene exposure estimates in certain groups of employees.

The role of human cytochrome P4503A4 in biotransformation of tissue-specific derivatives of 7H-dibenzo[c,g]carbazole.

The environmental pollutant 7H-dibenzo[c,g]carbazole (DBC) and its derivative, 5,9-dimethylDBC (DiMeDBC), produced significant and dose-dependent levels of micronuclei followed by a substantial increase in the frequency of apoptotic cells in the V79MZh3A4 cell line stably expressing the human cytochrome P450 (hCYP) 3A4. In contrast, neither micronuclei nor apoptosis were found in cells exposed to the sarcomagenic carcinogen, N-methylDBC (N-MeDBC). A slight but significant level of gene mutations and DNA adducts detected in V79MZh3A4 cells treated with N-MeDBC, only at the highest concentration (30µM), revealed that this sarcomagenic carcinogen was also metabolized by hCYP3A4. Surprisingly, DBC increased the frequency of 6-thioguanine resistant (6-TG(r)) mutations only at the highest concentration (30µM), while DiMeDBC failed to increase the frequency of these mutations. The resistance to 6-thioguanine is caused by the mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) gene. The molecular analysis of the coding region of Hprt gene showed a deletion of the entire exon 8 in DiMeDBC-induced 6-TG(r) mutants, while no changes in the nucleotide sequences were identified in 6-TG(r) mutants produced by DBC and N-MeDBC. Based on our results, we suggest that hCYP3A4 is involved in the metabolism of DBC and its tissue-specific derivatives. While hCYP3A4 probably plays an important role in biotransformation of the liver carcinogens, DBC and DiMeDBC, it might only have a marginal function in N-MeDBC metabolism.