Pharmacological intervention in the field of ototoxicity.

Modern research on ototoxicity goes back to the 1940s, when streptomycin was introduced into clinical practice. Today, aminoglycoside antibiotics and platinum-based chemotherapy, mainly cisplatin, are the most important drugs that damage the inner ear and cause hearing loss. The mode of drug administration as well as drug characteristics influence the likelihood that adequate monitoring of drug pharmacokinetics can be performed. It is not possible to predict the individual risk of treatment with an ototoxic drug, but identification of high-risk treatment protocols is important. There are many studies ongoing with the aim of discovering and developing drugs to treat different types of inner ear disorders. The mechanisms of ototoxicity and subsequent loss of hearing function have been mapped in various experimental models and have provided us with useful information for developing protective treatment. When an ototoxic lesion is established, restoration of hearing function becomes more difficult. For both aminoglycoside antibiotics and cisplatin, a large number of otoprotectors have been suggested. Systemic co-administration of an otoprotector would be the easiest approach to avoid ototoxicity in patients but it may negatively affect the intended pharmacotherapeutic aim of the ototoxic drug. New pharmacological formulations are being developed for local otoprotective treatment. This short review focuses on results from clinical reports on otoprotection in patients treated with aminoglycoside antibiotics and cisplatin. So far there is limited evidence for the safe management of otoprotection in patients. Further high-quality studies are needed to provide reliable data on the safety and effectiveness of pharmacological interventions to reduce drug-induced hearing loss.

Downregulation of miRNA-424: a sign of field cancerisation in clinically normal tongue adjacent to squamous cell carcinoma.

BACKGROUND: The overall survival for patients with squamous cell carcinoma of the tongue is low and the search for early diagnostic and prognostic markers is thus essential. MicroRNAs have been suggested as potential prognostic and diagnostic candidates in squamous cell carcinoma of head and neck in general. METHODS: On the basis of the known differences between sub-sites within the oral cavity, we investigated the expression and role of microRNA-424 in squamous cell carcinoma arising in tongue. MicroRNA levels were measured by qRT-PCR in both tissue and plasma samples. RESULTS: Levels of microRNA-424 were upregulated in tongue squamous cell carcinoma, but not in tumours originating from gingiva or floor of the mouth. Interestingly, microRNA-424 was downregulated in clinically normal tongue tissue next to tumour compared with completely healthy tongue, indicating that microRNA-424 could be a marker of field cancerisation in this tumour type. However, expression of microRNA-424 in a tongue-derived epithelial cell line revealed no significant changes in the expression profile of proteins and genes. CONCLUSIONS: Our patient data show that microRNA-424 alterations are a marker of field cancerisation specific for tongue tumourigenesis, which also could have a role in development of tongue squamous cell carcinoma.

Expression of p16 in squamous cell carcinoma of the mobile tongue is independent of HPV infection despite presence of the HPV-receptor syndecan-1.

BACKGROUND: Tongue squamous cell carcinoma (TSCC) is increasing in incidence, especially among young patients and preferably females. Infection with human papilloma virus (HPV) has been suggested as a cause of SCC in the head and neck, and the proportion of oropharyngeal cancers caused by HPV has steadily increased. METHODS: Samples from 109 patients with primary TSCC were analysed for the presence of HPV16 by in situ hybridisation and for expression of its surrogate marker p16 and the HPV receptor syndecan-1 by immunhistochemistry. RESULTS: No evidence of HPV16 DNA was observed in the tumours, although one-third showed p16 staining. There was no difference in the expression of the primary HPV receptor, syndecan-1, between TSCC and a group of tonsil SCC. CONCLUSION: Whereas p16 is expressed in some TSCCs, HPV16 is undetectable, therefore, p16 cannot be used as a surrogate marker for high-risk HPV-infection in this tumour. Despite presence of the HPV-receptor syndecan-1 in TSCC, HPV prefers the tonsillar environment. Lack of p16 associates with worse prognosis primarily in patients aged ⩽40 years with tongue SCC. The improved prognosis seen in p16-positive TSCC can be due to induction of a senescent phenotype or an inherent radiosensitivity due to the ability of p16 to inhibit homologous recombination repair.

Absence of high-risk human papilloma virus in p16 positive inverted sinonasal papilloma.

OBJECTIVES: Sinonasal inverted papilloma (SIP) is a relatively rare disease, and its etiology is not understood. It is characterized by locally aggressive growth and a strong tendency to recur despite its benign histology. AIMS: The aim of this study was to identify the presence of human papilloma virus (HPV) and its surrogate marker p16 in SIP tissue samples from a regional cohort. MATERIAL AND METHODS: Subjects were identified from our regional center cohort of 88 SIP patients treated between 1984-2014. From these subjects, 54 were included in this study. Of these, 53 biopsies were analyzed with PCR, and 54 samples were immunohistochemically stained for p16. DNA was extracted from histopathologically verified SIP. Genotype screening for 13 high risk-, 5 oncogenic and 6 low risk HPV types was performed using the PapilloCheck® HPV-screening test. RESULTS: HPV analysis was successful for 38 of 53 samples. Of the 38 successfully analyzed samples, only 2 samples were positive for HPV 11. Notably, p16 was present in the epithelia in all samples, and in the papilloma lesions in 37 samples. CONCLUSION: Since only 2 out of 38 SIPs were positive for HPV (type 11), and at the same time p16 was positive in epithelia in all samples and in 37 of 38 papilloma lesions of the samples, it is concluded that p16 cannot be used as a surrogate marker for high-risk HPV-infection in SIP. We are currently planning a prospective, multicenter study in order to increase the study power and in order to be able to better evaluate the clinical implications of HPV-and p16 in SIP.

High lead exposure and auditory sensory-neural function in Andean children.

We investigated blood lead (B-Pb) and mercury (B-Hg) levels and auditory sensory-neural function in 62 Andean school children living in a Pb-contaminated area of Ecuador and 14 children in a neighboring gold mining area with no known Pb exposure. The median B-Pb level for 62 children in the Pb-exposed group was 52.6 micrograms/dl (range 9.9-110.0 micrograms/dl) compared with 6.4 micrograms/dl (range 3.9-12.0 micrograms/dl) for the children in the non-Pb exposed group; the differences were statistically significant (p < 0.001). Auditory thresholds for the Pb-exposed group were normal at the pure tone frequencies of 0.25-8 kHz over the entire range of B-Pb levels, Auditory brain stem response tests in seven children with high B-Pb levels showed normal absolute peak and interpeak latencies. The median B-Hg levels were 0.16 micrograms/dl (range 0.04-0.58 micrograms/dl) for children in the Pb-exposed group and 0.22 micrograms/dl (range 0.1-0.44 micrograms/dl) for children in the non-Pb exposed gold mining area, and showed no significant relationship to auditory function.

Distribution of cisplatin in perilymph and cerebrospinal fluid after intravenous administration in the guinea pig.

The concentration of free cisplatin was followed in plasma, scala tympani perilymph and cerebrospinal fluid (CSF) after an intravenous injection (12.5 mg/kg) in guinea pigs. Liquid chromatography with postcolumn derivatization was used for quantitative determination of the drug. The distribution of cisplatin to CSF was fast; at 10 min after drug administration the concentration was 7 micrograms/ml and the CSF:plasma ratio was 0.37. Cisplatin seems to distribute more slowly to the perilymphatic compartment. The highest concentration measured was 4 micrograms/ml at 20 min after the injection, and the perilymph:plasma ratio was 0.40 at that time. The concentration-time curves generated for cisplatin in perilymph and CSF were similar. No accumulation in the perilymphatic compartment or CSF was observed.

The relative importance of the routes and sources of wound contamination during general surgery. II. Airborne.

The influence of airborne bacteria on wound contamination during biliary surgery was studied. When bacteria grew in the bile they accounted for most of the bacteria in the wound but when the wounds were free of bile bacteria many of the bacteria came from the patient's skin. It was only in wounds with little contamination from non-airborne routes that it was possible to demonstrate an effect of airborne contamination. In such a situation it was estimated that a reduction in the airborne bacteria in the operating room of about 13-fold would reduce the wound contamination by about 50%. The contamination of patient drapes from various sources and its relationship to wound contamination was studied. It was demonstrated that in areas away from the wound, the bacterial concentration on the drape surface was significantly affected only by airborne bacteria. In the area close to the wound, airborne bacteria and bacteria from the wound significantly affected drape contamination. However, it was found that more bacteria transferred from the wound to the drape surface than vice versa. Punctured gloves, impervious gowns and the number of bacteria on the patient's skin did not significantly affect the counts on the drapes' surfaces.

The relative importance of routes and sources of wound contamination during general surgery. I. Non-airborne.

A study was undertaken to determine the relative importance of some sources, routes of transmission, and measures to prevent bacteria entering the wound during biliary tract surgery. When bacteria were growing in the bile they accounted for the majority (greater than 99%) of the bacteria found in the wound. However, when the bile was sterile the skin bacteria at the incision site were found to make a substantial contribution to the wound flora. The difference in the total wound contamination between a patient who had practically no skin bacteria and one who had an average amount was in the region of 17-fold. No transfer of skin bacteria from the surgical team through perforated gloves or by direct contact from the surface of operating gowns was demonstrated. Ten of the patients studied had septic wounds. Five of these were infected by bacteria from the bile.

An investigation of occlusive polyester surgical clothing.

The bacterial dispersion rate of people wearing operating room clothing made from several types of polyester fabric was compared to conventional cotton clothing, total-body exhaust gowns and disposable clothing. Airborne bacteria were measured in a chamber, three ultra-clean air operating rooms and a conventionally ventilated operating room. The polyester clothing was demonstrated to be much superior to conventional cotton clothing and at least as good as the total-body exhaust gowns and disposable clothing.

Normal auditory brainstem and cochlear function in extreme pediatric plumbism.

Lead (Pb) intoxication in children has been associated with encephalopathy, sensory and cognitive impairments. We investigated the prevalence and neuro-sensory effects of Pb exposure in children living in Andean villages of Ecuador with high Pb contamination from discarded automobile batteries used in the local ceramics glazing industry. Venous blood samples were collected from 107 children in the Pb glazing area and from 39 children living in a geographically distant area with no known Pb contamination and measured for blood lead (PbB) levels. Auditory brainstem responses (ABR) and audiological/otological tests were conducted on children in the Pb-Glazing Group. The median PbB level for children in the Pb-Glazing Group was 40.0 microg per dl (range: 6.2-128.2 microg per dl) and for the non Pb-Glazing Group 6.0 microg per dl (1.9-18.0 microg per dl). The differences in PbB levels for children in the study and control areas were statistically significant (t-test, P<0.0001). ABR tests on the Pb-Glazing Group indicated normal wave latencies and neural transmission times, and no statistical correlation between PbB level and interpeak latencies. Audiological tests showed normal cochlear function and no statistical relation between auditory thresholds and PbB level. Contrary to prevailing assumptions, elevated PbB levels in children do not invariably impair auditory brainstem neural transmission or sensory-neural cochlear function, both of which have been implicated as significant contributors to the neurodevelopmental disabilities associated with childhood plumbism.

Field screening of blood lead levels in remote Andean villages.

Blood lead (PbB) levels were investigated in chronically lead (Pb) exposed Andean children and adults living in a highly Pb contaminated area of Ecuador where Pb glazing of ceramics is prevalent. A comparative study was made of the PbB levels of Pb-glazing and non-Pb-glazing families living in close proximity, using three PbB analysis techniques. Fifty-one, 50-microl blood samples from children and adults were analyzed in the field by a finger-stick capillary screening technique using the portable ESA LeadCare Blood Lead Testing System (LCS). Venous blood samples of 2-4 ml were collected from the same 51 participants and analyzed in the laboratory by inductively coupled plasma mass spectrometry (ICP-MS) and by graphite furnace atomic absorption spectrometry (AAS). The median PbB levels for the Pb-glazing group as determined by the ICP-MS, AAS and LCS techniques were 37.2 microg/dl (range 11.6-101.0), 32.0 microg/dl (range 8.0-70.0 microg/dl) and 44.0 microg/dl (range 19.0-105.0), respectively. The median PbB levels for the non-Pb-glazing group were 9.2 microg/dl (range 5.0-21.7) with ICP-MS, 9.0 microg/dl (range 4.3-32.0) with AAS, and 11.3 microg/dl (range 7.3-21.1) with LCS. The differences in PbB levels between the Pb glazing and non-Pb glazing groups were statistically significant (p = < .0001) for each PbB analysis method. Correlations between paired samples were: LCS and ICP-MS: r = 0.913, LCS and AAS: r = 0.829, and ICP-MS and AAS: r = 0.905. The results suggest that neighboring Pb glazing and non-Pb glazing families have significantly different PbB levels, and that the portable LCS field technique may be useful for screening and periodic monitoring of relatively low and high PbB levels of persons in remote high altitude Andean areas.

Blood mercury and auditory neuro-sensory responses in children and adults in the Nambija gold mining area of Ecuador.

This study investigated blood mercury (B-Hg) levels and the auditory neuro-sensory status of children and adults in the remote Andean settlement of Nambija, Ecuador where Hg is used in the extensive gold mining operations. The mean B-Hg level in 75 Nambija (Study Area) inhabitants (36 children and 39 adults) was 17.5 micrograms/L (SD = 11.0) vs 3.0 micrograms/L (SD = 1.6) in a second group of 34 subjects (15 children and 19 adults) in a non-gold mining area (Reference Area), the difference being statistically significant (p < 0.0001). Neuro-otological examinations revealed 34 subjects (45%) with complaints of headaches and/or memory loss, 3 cases of severe neurological impairment and 4 cases of middle ear pathology. Audiological tests on 40 persons in the Study Area (21 children and 19 adults) showed hearing thresholds ranging from normal to mildly abnormal at 2, 3, 4, 6 and 8 kHz for children, and normal to severely abnormal for adults. Correlation coefficients showed a significant relationship between B-Hg level and hearing level in children at 3 kHz in the right ear, and at no frequency for adults. Auditory brainstem evoked responses (ABR) on subjects in the Study Area showed a significant correlation between B-Hg and the I-III interpeak latency on the right side. The results indicated that the study population of the Nambija gold mining area had abnormally elevated B-Hg levels, and may be at neurological risk from exposure to methylmercury (MeHg) from the consumption of contaminated food and possibly from elemental Hg vapors inhaled during amalgam burning in the gold extraction process.

Cisplatin: effects on the stretch receptor neuron of the crayfish.

The effects of cisplatin on electrical and mechanotransducer properties of the crayfish stretch receptor neuron was studied using a microelectrode voltage clamp technique. In the stretch receptor neuron, negligible changes in membrane capacitance, leak conductance, resting membrane potential, potential-dependent currents or mechanoreceptor current were seen either on acute cisplatin treatment or after long-lasting treatment for up to 2 weeks. The inhibitory GABA-sensitive synapse on the neuron was not affected by cisplatin. The cisplatin cytotoxicity on sensory neurons such as outer hair cells of the organ of Corti cannot be explained by direct effects on ionic channels of these cells including stretch-activated channels.

The combined effect of cisplatin and furosemide on hearing function in guinea pigs.

The effect of the combined administration of cisplatin and furosemide on the electrophysiological hearing thresholds and endocochlear DC potential (EP) was studied in guinea pigs. A lack of interaction was found in animals given repeated intraperitoneal injections of a low dose of cisplatin with a pharmacological dose of furosemide. An ototoxic interaction occurred when a moderately high dose of cisplatin was administered intravenously at a time when the strial function was most affected by a very high dose of furosemide. The interaction was seen both as a decreased EP and a pronounced shift of auditory thresholds. It is concluded that the stria vascularis plays a role in the ototoxic mechanism of cisplatin.

The ototoxic effect of cisplatin on guinea pigs in relation to dosage.

The effect on the electrophysiological hearing thresholds and the endocochlear DC potential (EP) was studied in four groups of guinea pigs receiving different doses of cisplatin. By multiple low-dose intraperitoneal injections a permanent hearing loss was produced without a permanent decrease of the EP. On the other hand, when cisplatin was given as a single high-dose intravenous injection, there was an impairment of the electrophysiological hearing thresholds and EP, depending upon the level of cisplatin dose. It is concluded that cisplatin-induced hearing loss is not necessarily a sequela to a loss of EP.

Comparative entry of carboplatin and sucrose in endolymph in the rat cochlea.

The permeability of the perilymphatic-endolymphatic interface for carboplatin was determined after lateral cerebral ventricle infusion of radioactive carboplatin (cis-diamine[1,1-cyclobutane-1-14C-dicarboxylate]platinum) to rats. [14C]sucrose, a similar weight molecule was used for comparison of the kinetics in the inner ear fluids. 14C-radioactivity was measured in perilymph and endolymph. The rate of elimination of the tracers from perilymph was equivalent indicating no difference in transport across the blood-perilymph barrier. The transport from perilymph to endolymph was very restricted for both substances. The present study indicates that the ototoxic effect of carboplatin cannot be explained by a specific endolymphatic transport mechanism.

Effect of cisplatin administration on the electrochemical composition of endolymph in the rat cochlea.

The effect of cisplatin on the electrochemical composition of the cochlear endolymph was studied in Long-Evans rats three days after a single intraperitoneal injection (8 mg/kg b.w.). A dose 2/3 of LD50 induced a decrease of the endolymphatic concentration of potassium whereas the endocochlear potential was unaffected. The discrepancy between these two findings indicated that cisplatin did not alter the mechanisms involved in the genesis of the endocochlear potential but modified the passive K transport into endolymph.

Paracellular transport properties of inner ear barriers do not account for cisplatin toxicity in the rat.

The interindividual variability for the ototoxic effect of the antineoplastic drug cisplatin has still to be explained. To examine if the variability can be related to differences in drug kinetics, the effect of cisplatin on the paracellular transport properties of the inner ear barriers was studied in vivo in cisplatin treated Long-Evans rats. The concentration of [3H]mannitol was followed in plasma, scala vestibuli perilymph, and endolymph after an intravenous infusion of the tracer. Cisplatin had no effect on paracellular transport of the inner ear barriers 3 days after administration of 8 mg/kg cisplatin. However, an interindividual variability for the transport of [3H]mannitol across the blood-perilymph barrier was evident, indicating a variability for the passive transport of solutes to the inner ear.

Intracochlear administration of thiourea protects against cisplatin-induced outer hair cell loss in the guinea pig.

Amelioration of cisplatin-induced side-effects is of great clinical importance. Local administration of a cytoprotective agent to the inner ear offers a possibility to prevent cisplatin-induced ototoxicity without risk of interference with the antitumour effect. The ideal substance for local administration has yet to be identified. Thiourea (TU) has unique properties that make it an interesting candidate. This study was initiated to test the hypothesis that TU given by local administration protects against cisplatin ototoxicity in the guinea pig. After baseline auditory brainstem response (ABR) assessment, the left cochlea was implanted with a microtip catheter connected to an osmotic pump filled with either 27 mg/ml TU in artificial perilymph (AP), or AP administered for the full duration of the study. Three days post-implant, animals with normal ABRs received an intravenous injection of 8 mg/kg body-weight cisplatin. Five days after the cisplatin treatment ABRs were reassessed, animals decapitated and bilateral cytocochleograms prepared. TU-treated ears demonstrated significantly lower outer hair cell (OHC) loss as compared to contralateral untreated ears, and significantly lower OHC loss compared to AP-treated ears. ABR threshold shift did not differ significantly between the two groups. It can be postulated that TU demonstrates partial protection against cisplatin-induced ototoxicity.