Kanamycin Treatment Research Articles

Critical bands following the selective destruction of cochlear inner and outer hair cells.

Critical bandwidths and absolute intensity thresholds were measured in cats before and after kanamycin treatment which induced selective inner and outer hair cell losses. Hair cell losses were measured from cochleograms constructed from surface preparations of the organ of Corti. Results suggested that, for the test frequencies and stimulus intensities employed, critical bandwidths were not affected for frequencies tonotopically located in cochlear regions where only outer hair cells were lost. Critical bands were widened or not measurable only when inner hair cell losses exceeding 40% were also associated with complete loss of outer hair cells. The experiment suggests that cochlear frequency selectivity can be mediated by inner hair cells alone.

Effects of kanamycin on the auditory evoked responses during postnatal development of the hearing of the rat.

The ototoxic effects of kanamycin were studied in rats during the early postnatal period and at an adult age. Brain stem potentials as well as auditory cortical potentials were used for the estimating of ototoxic damage. The auditory potentials decreased promptly and markedly in the animals which were treated daily with 400 mg/kg body weight of kanamycin starting from the 11th day after birth. In these animals, the auditory potentials were almost completely abolished within 10 days after the beginning of the kanamycin treatment. However, when the same amount of kanamycin was applied earlier or later than that, i.e., avoiding the period of the initial appearance and the greatest development of auditory functions (from the 11th to the 15th day after birth in the rat), the auditory potentials were not apparently damaged. In light and scanning electronmicroscopy, marked ototoxic changes were observed which underlay the functional damage. The meaning of these findings is discussed.

The reduction in dental decay in rampant caries individuals following short term kanamycin treatment : LOESCHE W. J., BRADBURY D. R. and WOOLFOLK M. P. J. Dent Res.56 (1977) 254–265

The reduction in dental decay in rampant caries individuals following short term kanamycin treatment : LOESCHE W. J., BRADBURY D. R. and WOOLFOLK M. P. J. Dent Res.56 (1977) 254–265

Potentiation of kanamycin ototoxicity by a history of noise exposure.

Chinchillas were exposed to a noise band (1,414 to 5,656 Hz, 100-dB sound pressure level [SPL] for one hour) and treated with kanamycin (150 mg/kg a day until hearings loss was noted at 6.0 kHz) either separately, simultaneously, or sequentially. Simultaneous noise and kanamycin resulted in interactive potentiation of threshold shift and cochlear pathologic condition. Kanamycin treatment two months after noise exposure produced similar potentiation. No interaction was seen when noise exposure occurred one month after kanamycin treatment.

A possible involvement of acidic glycosaminoglycans in kanamycin ototoxicity.

The content of acidic glycosaminoglycans (AGAG) was determined quantitatively by electrophoretic microanalysis in the cochlea, kidney and brain of the guinea pig. Kanamycin treatment (400 mg/kg body weight/day, i.m., 10 successive days) reduced the content of AGAG markedly in the lateral wall of the membranous cochlea. Furthermore, from the results of the ultrahistochemical and freeze-fracturing study, we propose here an "excretion system for basic aminoglycoside antibiotics" by means of the co-operation of spiral ligament cells and AGAG produced by them. Thus we have tentatively concluded both that kanamycin is excreted via the above mentioned "excretion system" in the lateral wall of the membranous cochlea and that it damages this system to form the circulus vitiosus of its opopoxicity.

Results of hearing testing at 7-year follow-up of kanamycin-treated newborn infants.

A follow-up study 7--8 years after kanamycin treatment of 83 newborn infants in the Tampere University Central Hospital is described. The Apgar scores ranged from 1 to 10, about half of the patients being premature. Only in 1 case (1.2%) a slight bilateral high-tone loss was found. This patient's birth had been complicated by ablation of the placenta with subsequent cesarean section and he had neonatal sepsis as well. The cause of this hearing defect is thus not necessarily the use of kanamycin. Because of the extended use of reserve antibiotics, microorganisms resistant to modern antibiotics may necessitate in some vital cases the use of kanamycin. Our results indicate that, if serum concentrations are monitored adequately, the use of kanamycin does not necessarily result in a hearing defect.

Single-tone and two-tone responses of cochlear-nerve fibers: changes after kanamycin and noise treatments

Responses to single tones and two-tone inhibition (TTI) above CF were determined in untreated Mongolian gerbils and after kanamycin or impulse-noise treatment. Kanamycin produced maximum hair-cell damage in the basal cochlear turn, the noise, in the mid-cochlear region and sometimes in the base. Fibers associated with 100% loss of outer hair cells (OHC) in the basal turn showed elevated CF thresholds, reduced slopes of tuning curves, no TTI, steep rate-intensity curves above CF, and excitation during basilar-membrane displacement towards scala vestibuli. In the presence of 50–95% OHC loss restricted to 2–4 mm of the midcochlear region, corresponding fibers exhibited less homogeneous characteristics. CF thresholds corresponding to the basal boundary of the lesion were nearly normal and increased toward and beyond the apical boundary. The tuning curves tended to be somewhat broadened and TTI, though reduced, was still present in fibers with elevated CF thresholds. Fiber excitation usually occurred during basilar-membrane displacement towards scala vestibuli. Some fibers from both treated groups showed increased sensitivity below CF despite elevated CF thresholds. Tuning curves associated with no TTI had high-frequency slopes between 70–200 dB/oct.

Kanamycin priming for audiogenic seizures in mice

It is well established that mice can be made to suffer epileptic-like seizures when subjected to certain kinds of loud noises. Some strains of mice are genetically susceptible while others can be made susceptible by using acoustic priming techniques. It has been suggested that priming mice with a loud bell sound at a critical development age causes hair cell damage which is a necessary part of the audiogenic seizure syndrome. Since ototoxic drugs also cause such damage, non-susceptible BALB/C mice were given kanamycin sulphate 400 mg/kg daily from age 5 days to age 21 days and then tested for audiogenic seizures at age 28 days. Eighteen of the twenty mice which survived the kanamycin treatment displayed full epileptic-like seizures when subjected to loud sounds at age 28 days. Histological surface preparations of the organ of corti from these mice revealed extensive outer hair cell damage in all turns of the cochlea while the inner hair cells and a few outer hair cells in the apical turn appeared undisturbed. All of the cochlea nerve fibres appeared normal in the histological preparations. The relationship of these results to the phenomenon of recruitment is discussed.

Reduction of Dental Decay in Rampant Caries Individuals Following Short-Term Kanamycin Treatment

A week of kanamycin gel treatment before and after the placement of dental restorations, compared to a placebo gel treatment, significantly reduced the levels of cultivable bacteria, S mutans and S sanguis, in the plaque samples collected immediately after the completion of the gel treatments, and was associated with a 46% reduction in new carious surfaces in the 14- to 37-month period following the gel treatment.

Kanamycin and Gentamicin Treatment of Neonatal Sepsis and Meningitis

Mortality from neonatal meningitis due to gram-negative microorganisms remains 50% despite use of aminoglycoside antibiotics. Blood was obtained on 238 occasions from 77 neonates with putative or documented sepsis; paired blood and cerebrospinal fluid (CSF) samples were obtained on 14 occasions from ten neonates with meningitis. Kanamycin and gentamicin were measured by a radioisotopic assay procedure. Kanamycin was administered at 15 mg/kg/day in three divided doses intravenously; serum concentrations peaked at one hour (mean, 7.77mug/ml). Gentamicin was administered at 7.5 mg/kg/day in three divided doses intravenously; serum concentrations peaked at two hours (mean, 5.34mug/ml). Both aminoglycosides generally were nondetectable within the CSF; survival of neonates with gram-negative meningitis correlated specifically with the sensitivity of their isolates to ampicillin which was administered concurrently. This study suggests that alternative approaches to the treatment of neonatal sepsis should be explored; administration of an antibiotic which crosses the blood-cerebrospinal fluid barrier more readily should be considered.

Potentiation of cochlear injury by noise and ototoxic antibiotics in guinea pigs

Guinea pigs were exposed to 8-kHz octave band noise, eight hours daily for one week, while receiving kanamycin 200 mg/kg daily. Other groups of animals received kanamycin alone, noise exposure alone, or both treatments separated in time. Two weeks after kanamycin treatment, injury to the cochlea was assessed in terms of reduction in the microphonic potential (CM) recorded at the round window and hair cell loss as evaluated in surface preparations. Pathological changes were greatest when noise exposure was concurrent with kanamycin treatment or preceded it by only one week. Noise exposure alone and other sequences, with and without an intervening week of rest, produced lesser degrees of injury. The results are compatible with the hypothesis that noise exposure affects the hemato-labyrinthine barrier, causing a more rapid accumulation of the antibiotic in the inner-ear fluids and tissues or a reduced rate of clearance from them. [Supported by NIH-NIEHS contract NO 1-ES-2-2110 and NIH Program Project Grant 05785.]

Frequency selectivity mediated by inner hair cells alone

A well-recognized measure of frequency selectivity can be obtained by a tone-on-tone masking paradigm, which generates a so-called “psychophysical tuning curve” [e.g., A. M. Small Jr., J. Acoust. Soc. Am. 31, 1619–1625 (1959); E. Zwicker in Facts and Models in Hearing (Springer-Verlag, New York, 1974), pp. 132–139]. This procedure was adapted to chinchillas trained with the shock-avoidance method. In order to eliminate outer hair cells from controlled regions of the cochlea, kanamycin was administered. We have demonstrated previously that this method is suitable for producing relatively pure outer hair cell losses in the basal part of the cochlea, with the immediate psychophysical correlate of an approximately 40-dB threshold shift [A. Ryan and P. Dallos, Nature (in press, 1975)]. Measurements of the “tuning curves” both before and after kanamycin treatment indicated that (1) for maskee frequencies in the unaffected frequency region the “tuning curves” are unchanged, and (2) when the maskee is in the affected region, the segment of the “tuning curve” also within that region is simply shifted proportional to the threshold shift. The curves do not become wider. This suggests that the sharpness of tuning in the auditory system can be determined by inner hair cells, acting without significant influence by the outer hair cells. [Work supported by grants from the NINDS. We thank T. McGee and C. Sanes for their contribution to this research.]

Observation of click-evoked compound VIII nerve responses before, during, and over seven months after kanamycin treatment in the guinea pig.

Compound VIII nerve action potential responses to clicks and filtered-clicks were recorded regularly over a period of 7 months following Kanamycin treatment (8 days, 400 mg/kg), in 3 awake guinea pigs each with an implanted electrode on the round window (left ear). From the end of the treatment the responses to the click became dissociated in various degrees within three major phases: (1) a rapid phase (8 to 10 days) where the responses were dramatically altered, (2) a recovery phase which lasted about 2 months, (3) a slow phase over the subsequent 5 months where the responses to the click decreased slowly but gradually while the N 1 component, as well as the responses to the 8 000 Hz filtered-click (which became recruiting at the end of the treatment), disappeared progressively. Responses to the low frequency filtered-clicks were less affected. Cochlear cytograms showed almost complete degeneration of the inner and outer hair cells of the first turn only.

Phase opposition between inner and outer hair cells and auditory sound analysis.

Recordings of single-unit responses in the auditory nerve of normal and kanamycin-treated Mongolian gerbils indicate that inner and outer hair cells of the cochlea interact in phase opposition. After kanamycin treatment, the firing rate in some fibers is increased during the basilar membrane motion toward scala vestibuli, in others, during its motion towards scala tympani. Because of statistical correlation with anatomical changes and characteristic time patterns, the first response polarity is associated with inner hair cells, the second, with outer hair cells. It is shown that normal responses can be reconstructed from the two kinds of responses seen after kanamycin treatment. The phase opposition between inner and outer hair cells, in connection with the expected effect of spiral fibers, provides an explanation for neural sharpening of mechanical filter action in the cochlea.

Behavioral threshold, cochlear electrophysiology, and cochlear histology in kanamycin-poisoned chinchillas

Pure-tone thresholds of normal chinchillas were determined by the shock-avoidance procedure. Animals were then given daily kanamycin injections until a shift in threshold was observed. Injections were then terminated, and the threshold shift was allowed to stabilize. Approximately 30 days after the completion of kanamycin treatment, the animals were prepared for electrophysiological data collection. Intracochlear differential electrodes were placed in the first cochlear turn of both ears. Cochlear microphonic, summating potential, and compound action potential responses were collected. Finally, animals were sacrificed and the ears were prepared for histological examination by the surface preparation technique. Correlations between behavioral, electrophysiological, and histological measures are discussed. [This research was supported by grants from NINDS.]

Reduction of supragingival plaque accumulations in institutionalized Down's syndrome patients by periodic treatment with topical kanamycin

A small group of institutionalized Down's syndrome patients were treated with topical kanamycin sulphate paste, once or twice a day for 3–5 days, every fifth week over a 52-week-period. The teeth were not brushed during this 52-week-period. The wet weight of the supragingival plaque in the kanamycin group was significantly reduced when compared to the supragingival plaque formed in the group receiving a placebo paste. The gingivitis score of the kanamycin group did not deteriorate during the period of antibiotic administration despite the absence of oral hygiene procedures. No increase in kanamycin-resistant bacteria or yeasts were detected in plaque or tongue samples during the period of kanamycin treatment.

Isolation of R factors conferring kanamycin resistance from tuberculous patients treated with kanamycin.

In a survey of 228 tuberculous patients who had received kanamycin (KM) treatment, KM-resistant Escherichia coli or Escherichia freundii were isolated from 29. From the patients who had not received KM-therapy, KM-resistant strains were not isolated. Of the 29 KM-resistant strains isolated, 5 E. coli strains were also resistant to other aminoglycoside antibiotics, i.e., paromomycin, fradiomycin and streptomycin. They were also resistant to chloramphenicol and sulfanilamide and all of these resistances could be transferred to E. coli strains by conjugation. The resistance was considered to be conferred by an R factor. The remaining 24 KM-resistant strains were identified as E. freundii. In these level of KM-resistance was rather low and conjugal transfer was not observed. All were resistant to paromomycin but sensitive to fradiomycin. When 381 KM-sensitive strains were plated on an agar plate containing 25 μg of KM/ml, 23 KM-resistant strains were isolated. The mutants thus obtained were similar to the second type of 24 KM-resistant strains isolated from patients. Thus it was strongly suggested that the 24 strains carrying low levels of KM- and paromomycin-resistance, that is, conjugally nontransmissible, appeared by spontaneous mutation in the intestines of patients who had received KM-treatment.

Use of kanamycin for the isolation of auxotrophic mutants of Actinobacillus mallei.

Growth of Actinobacillus mallei was inhibited by kanamycin; the minimal inhibitory concentration in a complex medium was 1.25 μg/ml and in a chemically defined medium 5 μg/ml. Higher concentrations of kanamycin had a pronounced bactericidal effect. When a suspension of cells containing 5 × 107 viable cells/ml was incubated in the presence of 20 μg/ml of kanamycin in a chemically defined medium, complete sterilization resulted after 6 hours. Cells irradiated with ultraviolet light were grown in complex or supplemental minimal media, washed, and exposed to 20 μg/ml of kanamycin in minimal medium for 4 hours. Auxotrophic mutants with requirements for tryptophane, phenylalanine, proline, and uracil were detected among the survivors of kanamycin treatment. After treatment with 0.01 M nitrous acid and growth in minimal medium supplemented with amino acids, cells were washed and then exposed to kanamycin in minimal medium. The proportion of autotrophs among the survivors varied from 1.3 to 75%. Mutants with requirements for each of the following amino acids were identified: methionine, methionine or cystine, arginine, leucine, tryptophane, histidme, and proline, with methionine-requiring mutants predominating. Exposure of mixtures of prototrophs and uracil-dependent and methionine-dependent auxotrophs to 20 μg/ml of kanamycin for 4 hours resulted in approximately 700- and 300-fold increases, respectively, in the ratio of auxotrophs to prototrophs.

EFFECT OF KANAMYCIN ON HEARING ABILlTY

Since kanamycin(KM) treatment is known to cause auditory disturbances as in streptomycin(SM) treatment, the power of hearing was investigated in TB patients, who had either SM or KM treatment of varying duration, and the results may be briefly summarized as follows: 1. The effect of the KM 2gm twice weekly on the power of hearing was similar to SM 1gm twice weekly in causing slight deafness. 2. The auditory impairment due to the KM was directly related to the length of treatment. The administration of KM 2gm twice weekly for more than 6 months resulted in a decrease in hearing of more than 15db at 8,000 cps on the audiogram, while little adverse effect was recorded KM treatment it was administered for less than 6 months.

Cytoarchitectural Changes in Corti's Organ after Kanamycin Treatment and Acoustic Trauma

Changes in the cytoarchitectural pattern of the organ of Corti were studied in two groups of guinea pigs. One had been treated with kanamycin in doses of 200–400 mg/kg/day for 5–20 days. The other group had been exposed to tones of 500–4000 cps at 140–150 dB SPL. Examination of surface preparations of the organ of Corti by phase-contrast microscopy revealed loss of outer hair cells in both groups of animals. In the kanamycin group, the greatest loss was at the basal end of the organ of Corti. In the acoustic-trauma group, the site of loss varied somewhat, as might be expected, with the exposure frequency, but was greatest in the first and second turns. Severe destruction was visible under the dissecting microscope, without the aid of greater magnification. In acoustic trauma, loss of pillar cells was also seen, whereas kanamycin caused loss of Caludius cells in the basal turn. The results are illustrated with photomicrographs and maps of the organ of Corti.