[Auditory thresholds in young Italians from 18-19 years of age]. / La soglia uditiva in giovani italiani di 18-19 anni.

The aim of the study was to assess the state of hearing levels in young Italian subjects via an epidemiological study, and also, by means of a questionnaire, to assess the attitude of young people to music, how they listen to music and how they perceive the risk of noise-induced hearing damage. The sample studied consisted of 391 youths undergoing their first medical examination for military service. The hearing threshold was assessed by means of a semiclinical tonal audiometry with sound-proof earphones calibrated to ISO Standard 389 following the method of ISO Standard 6189. At the end of the study 315 youths were judged eligible for the study, 81% of whom lived in the city of Milan. 63% said they went to a discotheque 1-4 times a week and 3% said they listened to music with earphones at maximum volume. These conditions are considered to be potentially dangerous for hearing since among youths leaving discotheques disorders have been observed that are indicative of hearing fatigue: lowering of the hearing level 7%, buzzing in the ears 37%, sense of muffled sound 12%. In the group studied, environmental noise was a factor of disturbance for sleep (13%), for study and reading (43%), listening to the radio, to music and watching TV (29%). Only 7 youths said their hearing was "not normal", but the thresholds were all higher than audiometric zero, which are clearly worse than the values observed in similar studies reported in the literature. This study reports the mean values, SD, minimum and maximum and centile values of the distribution of hearing thresholds, separately for right and left ears. A comparison was made between the hearing in the group least exposed: a significant difference was observed only for the right ear while for the left ear there was only a tendency. The authors conclude that hearing in young people to-day is worse than in the past, whatever be the causes, and that due account should be taken of this state of affairs, by encouraging prevention programmes for noise-induce hearing loss at all levels and on every possible occasion.

Relation of dosing regimen to aminoglycoside ototoxicity: evaluation of auditory damage in the guinea pig.

Groups of guinea pigs were injected intramuscularly for 21 days with netilmicin or amikacin 150 mg/kg/day by one or three daily injections. Amikacin was also tested at 225 mg/kg/day with each dosing regimen. Auditory function was evaluated during the experiment by reflexological and electrophysiological tests. Morphological damage to the inner ear was also evaluated. Netilmicin had no effect on the auditory function nor did it damage the organ of Corti. Conversely, amikacin impaired the auditory function and produced loss of hair cells in a dose-related manner. The effect was equally marked with both dosing regimens of 225 mg/kg/day, whereas a slight decrease of auditory impairment was observed with 150 mg/kg administered once a day. The data suggest that administration of a single daily dose of aminoglycosides does not increase the risk of ototoxicity specifically associated with each compound.

[Evoked auditory potentials of medium latency in subjects with normal hearing]. / Potenziali evocati uditivi a media latenza (MLC) in soggetti normoudenti.

The parameters of normality in MLC to frequency-specific click and tone burst stimuli are analysed. Thirty four patients aged 15-50 with normal hearing revealed by preliminary subjective audiometry and impedance examination are examined for the following variables: threshold, latency, amplitude and repetitivity in response to click and tone burst stimuli. The audiometric and psychoacoustic thresholds were found to be closely connected. The MLC latency was in the 8-80 msec range as reported in the literature. Amplitude was neither significant nor reliable as a parameter since it varied so much from patient to patient, whereas the repeatability over time of these evoked potentials demonstrated their reliability. The results of this study confirm the view that MLC analysis is a valuable addition to the battery of diagnostic tests in routine use.

Comparative ototoxicity of dibekacin and netilmicin in guinea pigs.

The cochleo- and vestibulotoxicity of dibekacin and netilmicin were compared in a guinea pig model. Both aminoglycosides were administered subcutaneously for 21 days at the dose level of 150 mg/kg/day. Control animals were injected with saline. Dibekacin-treated animals showed a significant (P less than 0.05) increase in the thresholds of the Preyer pinna reflex and the VIIIth nerve compound action potential in response to sound click stimulation. Moreover, a deterioration of the electrophysiologic auditory response and an almost complete suppression of the post-rotatory nystagmus were detected. In contrast, netilmicin did not induce any significant change in auditory and vestibular functions as compared to the control group. Our results demonstrated that netilmicin was devoid of ototoxicity in the guinea pig, while dibekacin provoked mild cochlear and severe vestibulotoxicity.

[In vitro anti-fungal activity of the econazole-ornidazole combination (1:10 ratio)]. / Attività antimicotica "in vitro" dell'associazione econazolo-ornidazolo (rapporto 1:10).

The antifungal activity of Econazole-Ornidazole combination (ratio 1:10) has been evaluated against 90 strains of Candida spp. recently isolated from a clinical environment. Minimal Inhibitory Concentrations (MICs) has been determined by a dilution broth method in test tube with Mycophil Broth (B.B.L) at pH 7.00 and drug concentrations ranging from 800 micrograms/ml to 0.2 microgram/ml. By the same technics it has been determined the pH influence of growth medium, human serum and fungal inoculum on the activity of the association towards the three strains of Candida spp.: C. albicans, C. krusei and C. tropicalis. The obtained data have shown that the Econazole-Ornidazole combination actuates a sure synergic effect towards the tested Candida strains. Such synergism is met at pH 8.00. The plasma proteins influence negatively the antifungal activity of the association proportionally to the increase of the concentration. The same thing happens with the inoculum of yeast. However, this decrease of activity of the association is always smaller than the one found in the compounds alone.

Comparison between brainstem-evoked response audiometry and behavioral audiometry in 270 infants and children.

The authors refer their results obtained with brainstem-evoked response audiometry (BSERA) and behavioral audiometry in a group of 270 children (aged from 6 months to 12 years) divided into subjects with (group A) and without (group B) reliable audiograms. In group A an agreement between the two methods was found in 77% of cases and a serious discrepancy in 5%. In group B an agreement was found only in 34% of cases, while a serious discrepancy was found in 20% of the children. BSERA was useful because many diagnostic mistakes were avoided. The authors think that BSERA is a reliable technique, as their data show, but in at least 4 cases they found that BSERA gave a hearing level much higher than that obtained with behavioral audiometry or that observed in the children's responses to everyday sounds. Since click gives only partial information of the tonal field and because it is possible to make technical mistakes, the authors believe that BSERA must not be used as the only diagnostic test but that it should be part of a test battery which includes, at least, behavioral audiometry and impedance audiometry.

[In vitro and in vivo antimicrobial activity of cefuroxime cefamandole and cephalexin on freshly isolated strains of Gram-positive and Gram-negative bacteria]. / Attivita antimicrobica "in vitro" ed "in vivo" del cefuroxime, del cefamandolo e della cefalexina verso ceppi microbici Gram-positivi e Gram-negativi di recente isolamento.

The Authors studied the antibacterial activity "in vitro" and "in vivo" of cefuroxime, cefamandole and cephalexin on the Gram-positive and Gram-negative bacterial strains of recent isolation. The results showed a greater antibacterial activity of cefuroxime than the other two cephalosporins, mainly on the Gram-negative beta-lactamase producing bacterial strains.

[The production of enzymes inactivating various antibiotics obtained from Gram-negative bacteria recently isolated in the province of Chieti]. / Studio della produzione di enzimi inattivanti vari antibiotici ad opera di germi Gram-negativi recentemente isolati in provincia di Chieti.

The Authors have studied the ability of producing enzymes blocking various antibiotics by 274 Gram-negative germs isolated in the years 1978-80 in the Province of Chieti (Italy). The results have showed that a high percentage of examined strains presents a polyresistance towards penicillins, cephalosporins, chloramphenicol and amino-glucosides producing in the same time beta-lactamase, acetyl-transferases and phospho-transferases.

Histological evaluation of ototoxic reaction due to some aminoglycoside antibiotics.

Twenty-one days s.c. treatment with netilmicin, gentamicin, sisomicin, and kanamicin at different doses were performed in albino guinea pigs of both sexes. Block surface preparation of Corti's organ was carried out and missing OHCs and IHCs counted in selected areas of each turn. The animals treated with gentamicin and sisomicin showed a dose-depending missing of hair cells, preferably relative to the outer ones and quantitatively the same for both the antibiotics. Furthermore, a characteristic distribution of the damage progressively increasing from the apex to the basal turn of the cochlea was detected. Kanamicin at 267 and 400 mg/kg gave the complete destruction of OHCs and IHCs along the whole cochlea while at 178 mg/kg did not show any significant damage in comparison to the control group. Finally, netilmicin neither damaged Corti's organ nor statistically determined missing OHCs and IHCs at all the doses used. These histological results and the previous electrophysiological and reflexological observations obtained in the guinea pig show a higher safety of netilmicin in comparison to the other aminoglycosides used for the problem relative to ototoxicity.

Auditory function in guinea pigs treated with netilmicin and other aminoglycoside antibiotics.

The following aminoglycoside antibiotics netilmicin, sisomicin, gentamicin, and kanamycin were submitted to a comparative study of their ototoxicity using both reflexological (Preyer's pinnareflex) and electrophysiological (near and far field) methods. The daily s.c. administration of sisomicin, gentamicin, and kanamycin for 21 days provoked a dose-related impairment of the cochlear function, detected with all the employed techniques. On the other hand, a very low ototoxic effect of netilmicin was demonstrated with electrophysiological but not with the reflexological evaluation. The reliability of the methods used in these experiments is also compared.

Late evoked responses to acoustic stimuli in relation to age.

Late hearing potentials (contigent negative variations; CNV) were studied in 66 subjects of different ages: 15 children, 26 adults and 25 elderly people (extreme ages of 4 and 100 years). Particular care was taken in selection of phonetic material suitable for each age. No CNVs were recorded in children under the age of 5 years; only 2 of the children examined presented late responses for all the phonetic lists. In adults, such cases rose to 5(19.2%), while another 16(61.5%) presented responses for some or a good part of the lists in question. Only in 9 elderly people were typical CNVs observed (36%). The discussion outlines the reasons for the low percentages of late responses obtained in children and point out that in some elderly subject accustomed to psychic and motor activities typical CNV are present.