[Inner hair cells loss by carboplatin and the changes of cochlear compound action potential in chinchillas].

Objective: To measure the cochlear compound action potential (CAP) and the densities of hair cells (HCs) along the whole length of the basilar membrane (BM) in adult chinchillas. And to investigate the relationship between the severity of inner hair cells (IHCs) loss and the changes of CAP by using carboplatin-cochlear lesion model. Methods: Totally 18 chinchillas were recruited after ontological evaluation. They were randomly divided into three groups (with 6 subjects in each), A: control, B and C: legion groups treated with one or two shot(s) of carboplatin respectively (76 mg/kg in one shot, i.p., one-week interval between the two shots). Endpoint tests were performed 30 days after the carboplatin treatment in groups B and C, and matched time in group A. A sliver-ball electrode was placed into round window niche via hypotympanic approach in anesthetized chinchilla. CAP was measured in response to clicks and tone burst of 0.5, 1, 2, 4, 8, 16 kHz respectively under anesthesia. CAP amplitudes and thresholds were measured and compared across the groups. After the recording, the whole cochlea surface preparation was made and the HCs were stained in histochemistry against substrate of succinate dehydrogenase (SDH). Images were taken with high-resolution digital camera under light microscope and across the whole cochlea. The length of the basilar membrane (BM) and the number of both IHCs and OHCs were counted. The HC density was calculated as the number of HCs per 10% BM length. Results: The CAP thresholds were (7.1±2.6), (25.4±5.0), (24.6±5.4), (10.4±5.0), (0.4±1.4), (4.2±6.3) and (17.1±14.1) dB SPL (from 6 subjects in group A, n=12 ears) corresponding to stimuli of Click and 0.5, 1, 2, 4, 8, 16 kHz tone bursts respectively. The total number of cochlear HCs were measured as (8 936±643) (x±s) and the average length of the BMs was (17.73±1.012) mm from the six subjects in the group A (n=12 ears). The HC density was found to be varied slightly across the BM. There was no significant CAP threshold difference between the control (group A) and the group B, which received one shot of carboplatin. However, the maximal CAP amplitude was reduced by 40% in the group B and compared with group A. Correspondingly, approximately 40% loss of IHCs were seen. In contrast, a significant CAP threshold shift was seen in subjects receiving two shots of carboplatin (group C), which was accompanied by a loss of 90% IHCs. Conclusions: The CAP thresholds of adult chinchillas show typical open-V shape with the lowest values at 2, 4, and 8 kHz. IHC loss by carboplatin in certain degree is well correlated with CAP amplitude reduction, but does not change the threshold when inner hair cell loss reaches 40%, however, if inner hair cell loss exceeds 80%, the threshold shift of CAP will be inevitable.

Predictive values of clinical and pathological parameters for malignancy of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) possess a wide spectrum of biological properties, from indolent to highly aggressive. In this study, we evaluated a set of clinical and pathological parameters for their predicative values for malignancy of GISTs by retrospective reviews of tumor specimens and their relevant medical records from 840 patients. All GIST cases were first assigned as malignant if they met any of the following criteria: gross spreads, including liver metastassis and/or peritoneal dissemination, microscopic spreads, including lymph node metastasis, infiltrations to vascular, fat, nerve and muscularis mucosal tissues, or relapse. The remaining cases were recorded as biological behavior uncertain. This initial assignment revealed a set of five morphological features to be associated with malignancy. They were: mitotic counts greater than 10 per 50HPFs (P<0.0001), muscularis propria infiltration (P<0.0001), coagulative necrosis (P<0.0001), perivascular growth pattern (P=0.005), and severe nuclear atypia (P=0.014). Therefore, a new classification system, including criteria of 2 gross spreads, 5 microscopic spreads, and 5 histopathological parameters was developed. All the GIST cases were re-classified into a group of 485 malignant tumors, and a group of 355 nonmalignant tumors. Patient follow-up data revealed 5-year disease-free and overall survival rates as high as 99.3% and 100% for the nonmalignant group, but low rates of 43.9% and 59.7% for the malignant group. These results demonstrated a correlation of the new classification with clinical outcomes. Therefore, this set of 12 parameters has predictive values for malignancy of GISTs, and is potentially useful in the grading of the tumors.