The aim of the present study was to assess the ototoxicity of kanamycin sulfate (KM) in adult rats and its underlying mechanism. Forty male Sprague-Dawley rats (6-7 weeks old) were randomly divided into the experimental group and the control group. The animals in the experimental group were injected subcutaneously with KM (500 mg/kg per day) for two weeks, and the control group received equal volume of normal saline. To assess the ototoxicity of KM, the auditory brainstem response (ABR) was recorded to monitor the changes in hearing thresholds, and the density of spiral ganglion cells (SGCs) and morphology of cochlea were observed using surface preparations and frozen sections of cochlea. The results showed that the hearing threshold of rats in the experimental group was elevated by more than 60 dB across all the frequencies two weeks after the first administration of KM. And in the experimental group, the density of SGCs became lower, and organ of Corti suffered loss of hair cells. The loss of outer hair cells (OHCs) was more severe than that of inner hair cells (IHCs), correlated with the density decrease of SGCs. We conclude that the ototoxicity of KM in the adult rats was apparent and the underlying mechanism is associated with the loss of SGCs and hair cells.
Animals ; Cochlea ; drug effects ; pathology ; Evoked Potentials, Auditory, Brain Stem ; drug effects ; Hair Cells, Auditory, Outer ; cytology ; drug effects ; pathology ; Hearing Loss ; chemically induced ; physiopathology ; Kanamycin ; toxicity ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spiral Ganglion ; pathology ; physiology ; ultrastructure

OBJECTIVETo study the changes of platelet in May-Hegglin anomaly (MHA) and the molecular pathogenesis mechanism.

METHODSPeripheral blood was drawn from the MHA proband, her father and her uncle. Platelet count and morphology were examined by automatic blood cell counter and microscopy, respectively. The platelet membrane protein was examined by flow cytometry. Membrane antibodies were determined by ELISA. PCR was used to amplify the exons 25, 31 approximately 32, 38 and 40 of the MYH 9 gene in the MHA patient and her diseased father. Furthermore, PCR products were sequenced, a specific point mutation was identified and inclusions (Dohle's body) in the neutrophil was detected by indirect immunofluorescence technique.

RESULTSIt was proved that in MHA patients, platelet count was higher by cell counter than by microscope (P < 0.01). Giant platelet was 94% but platelet membrane proteins (CD41, CD61, CD42A, CD42b) were in normal range. Membrane antibodies was undetectable. An A5521G mutation (GAG-->AAG) in the exon 38 was found in the proband and her diseased father, resulting in a characteristic change of NMMHC-A1841 (Glutamic acid-->Arginine), which was not found in other members of the family and in normal controls. Spindle-like inclusions with fluorescence were clearly displayed in neutrophil cytoplasm.

CONCLUSIONThe molecular pathogenesis mechanism of May-Hegglin anomaly is the mutation in MYH 9 gene.

Adult ; Base Sequence ; Blood Platelets ; metabolism ; pathology ; DNA Mutational Analysis ; Enzyme-Linked Immunosorbent Assay ; Female ; Flow Cytometry ; Granulocytes ; metabolism ; pathology ; Humans ; Inclusion Bodies ; metabolism ; pathology ; Male ; Molecular Motor Proteins ; genetics ; Mutation ; Myosin Heavy Chains ; genetics ; Pedigree ; Platelet Count ; Platelet Membrane Glycoproteins ; metabolism ; Thrombocytopenia ; blood ; genetics ; pathology