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Pigmentation disorders such as albinism are occasionally associated with hearing impairments in mammals. Therefore, we wanted to investigate whether such a phenomenon also exists in non-mammalian vertebrates. We measured the hearing abilities of normally pigmented and albinotic specimens of two catfish species, the European wels Silurus glanis (Siluridae) and the South American bronze catfish Corydoras aeneus (Callichthyidae). The non-invasive auditory evoked potential (AEP) recording technique was utilized to determine hearing thresholds at 10 frequencies from 0.05 to 5 kHz. Neither auditory sensitivity nor shape of AEP waveforms differed between normally pigmented and albinotic specimens at any frequency tested in both species. Silurus glanis and C. aeneus showed the best hearing between 0.3 and 1 kHz; the lowest thresholds were 78.4 dB at 0.5 kHz in S. glanis (pigmented), 75 dB at 1 kHz in S. glanis (albinotic), 77.6 dB at 0.5 kHz in C. aeneus (pigmented) and 76.9 dB at 1 kHz in C. aeneus (albinotic). This study indicates no association between albinism and hearing ability. Perhaps because of the lack of melanin in the fish inner ear, hearing in fishes is less likely to be affected by albinism than in mammals.

SUMMARYOtophysine fish possess Weberian ossicles, which connect the swimbladder to the inner ear and improve hearing ability. There is a high diversity in the morphology of the swimbladder and Weberian apparatus in catfishes, which might affect hearing. We have examined these structures in representatives of six families with large, single bladders (Ariidae, Auchenipteridae, Heptapteridae,Malapteruridae, Mochokidae, Pseudopimelodidae) and five subfamilies from two families (Callichthyidae, Loricariidae) having small, paired, encapsulated bladders. We tested their hearing abilities utilizing the non-invasive auditory evoked potential recording technique. Species with single,non-encapsulated, free airbladders possess one, three or four ossicles,whereas species with encapsulated bladders possess one or two. The relative sizes of the bladders and ossicles were significantly smaller in the latter group. All species were able to detect sound stimuli between 50 Hz and 5 kHz. Interspecific differences in hearing sensitivity varied at most by 24 dB below 1 kHz, whilst this variation increased to more than 50 dB at higher frequencies. Catfishes with free bladders had lower thresholds above 1 kHz than those having encapsulated ones. The relative lengths of swimbladders and of ossicular chains were correlated with hearing sensitivity above 1 and 2 kHz, respectively. The number of ossicles affected hearing at 4 and 5 kHz. These results indicate that larger bladders and ossicles as well as higher ossicle numbers improve hearing ability at higher frequencies in catfishes. We furthermore assume that the tiny bladders have minimized their hydrostatic function but were not completely lost because of their auditory function.

Background. Numerous investigations have examined prognostic factors for patients with primary cutaneous melanoma. However, only a few studies have been published on the definition of prognostic groups. The first aim of the present study was to determine the relative importance of different prognostic factors in a large collective study. The second aim was to define prognostic groups of patients based on combinations of prognostic factors and to define a model that allows the estimation of individual survival probability. Methods. Long term follow-up of 5264 patients with invasive primary cutaneous melanoma was performed from 1970 to 1988 at four German University Departments of Dermatology (Berlin-Steglitz, Miinster-Hornheide, Tiibingen, and Wurzburg). The multivariate Cox model was used to analyze 5093 patients, and 4371 patients with complete information were included in a classification and regression tree analysis (CART). Results. Tumor thickness, sex, anatomic location, and level of invasion were highly significant prognostic factors according to the multivariate analysis (P < 0.0001). However, histologic subtype and age influenced prognosis less significantly (P < 0.05). The CART analysis resulted in 12 groups defined mainly by tumor thickness, sex, and anatomic location, which were combined into five prognostic groups. The prognostic stratification defined by the five groups was superior compared with the standard TNM model. Ten-year survival rates of the five groups ranged from 97% to 14% (P < 0.0001), and an equation was used to calculate individual survival probabilities based on the significant factors of the Cox model. Conclusions. Consideration of all significant prognostic factors of patients with primary cutaneous melanoma investigated in the present study allows for the definition of prognostic groups with a more reliable estimation of prognosis than by previous staging systems and also enables calculation of individual survival probabilities. Cancer 199575 :2484-91.

Background. Anatomic location has been identified by several investigators as a significant prognostic factor for patients with primary cutaneous melanoma (CM). However, the best determination of higher and lower risk sites is still controversial, and the biologic significance of tumor site in the course of primary CM is unknown. The aim of the present study was to identify higher and lower risk sites based on multivariate analysis. Methods. A series of 5093 patients with invasive primary cutaneous melanoma followed from 1970 to 1988 at four university centers in Germany was investigated using the multivariate Cox proportional hazard model to analyze the importance of anatomic location for survival probability. Results. The anatomic location was found to be a highly significant prognostic factor for patients with primary melanoma by multivariate analysis (P < 0.0001). An optimized classification into sites of higher and lower risk with respect to survival was evaluated by multivariate analysis controlling for the possible confounding effects of the other significant prognostic factors. Relative to the lower leg as the prognostically favorable baseline, the following locations were associated with a significantly higher risk of death caused by primary cutaneous melanoma : back and breast (thorax), upper arm, neck, and scalp (TANS regions). The lower trunk, thigh, lower leg, foot, lower arms, hands, and face were identified as lower risk sites. Conclusions. Anatomic location was confirmed as an independent prognostic factor for patients with primary cutaneous melanoma. The TANS regions were identified as high risk sites, and the lower trunk, thigh, lower leg, foot, lower arms, hands, and face were identified as intermediate sites. Cancer 199575 :2492-8.

Background. Maximum tumor thickness and level of invasion are known to be the most important prognostic factors for patients with primary cutaneous melanoma. However, the classification of tumor thickness and the question of whether the combination of tumor thickness and level of invasion provides a better prognostic classification than tumor thickness alone are still matters of debate. The present study examined the relationship between tumor thickness and survival probability to define cutoff points of tumor thickness. Secondly, it investigated the prognostic value of the combination of tumor thickness and level of invasion as proposed in the current TNM classification system. Methods. A series of 5093 patients with invasive primary cutaneous melanoma followed from 1970 to 1988 at four University centers in Germany (Departments of Dermatology in Tiibingen, Wiirzburg, Berlin-Steglitz, and at the Fachklinik) were analyzed by multivariate Cox models. Results. The relationship between tumor thickness and relative risk of death caused by melanoma was found to be almost linear to a tumor thickness of 6 mm. For tumors greater than 6 mm, no further marked increase in relative risk was observed. The stratification of tumor thickness with endpoints at 1,2, and 4 mm resulted in the best fit to the authors' data among all classifications with three endpoints, but differences were only slight. By multivariate analysis, the combination of tumor thickness and level of invasion as proposed by the current TNM classification were found to be prognostically less significant than tumor thickness alone. The prognostic influence of level of invasion was proved statistically only for tumor thickness less than or equal to 1 mm. Conclusions. The proposed stratification of tumor thickness with cutoff points at 1, 2, and 4 mm was supported by multivariate statistical analysis. The analysis of the current TNM staging system indicates the precedence of tumor thickness for the staging of patients with primary cutaneous melanoma in the case of discordance between tumor thickness and level of invasion. Cancer 1995 ;75 :2499-2506.

BackgroundThe weberian apparatus of otophysine fishes facilitates sound transmission from the swimbladder to the inner ear to increase hearing sensitivity. It has been of great interest to biologists since the 19(th) century. No studies, however, are available on the development of the weberian ossicles and its effect on the development of hearing in catfishes.Methodology/principal findingsWe investigated the development of the weberian apparatus and auditory sensitivity in the catfish Lophiobagrus cyclurus. Specimens from 11.3 mm to 85.5 mm in standard length were studied. Morphology was assessed using sectioning, histology, and X-ray computed tomography, along with 3D reconstruction. Hearing thresholds were measured utilizing the auditory evoked potentials recording technique. Weberian ossicles and interossicular ligaments were fully developed in all stages investigated except in the smallest size group. In the smallest catfish, the intercalarium and the interossicular ligaments were still missing and the tripus was not yet fully developed. Smallest juveniles revealed lowest auditory sensitivity and were unable to detect frequencies higher than 2 or 3 kHz; sensitivity increased in larger specimens by up to 40 dB, and frequency detection up to 6 kHz. In the size groups capable of perceiving frequencies up to 6 kHz, larger individuals had better hearing abilities at low frequencies (0.05-2 kHz), whereas smaller individuals showed better hearing at the highest frequencies (4-6 kHz).Conclusions/significanceOur data indicate that the ability of otophysine fish to detect sounds at low levels and high frequencies largely depends on the development of the weberian apparatus. A significant increase in auditory sensitivity was observed as soon as all weberian ossicles and interossicular ligaments are present and the chain for transmitting sounds from the swimbladder to the inner ear is complete. This contrasts with findings in another otophysine, the zebrafish, where no threshold changes have been observed.

Background Surveys of ontogenetic development of hearing and sound production in fish are scarce, and the ontogenetic development of acoustic communication has been investigated in only two fish species so far. Studies on the labyrinth fish Trichopsis vittata and the toadfish Halobatrachus didactylus show that the ability to detect conspecific sounds develops during growth. In otophysine fish, which are characterized by Weberian ossicles and improved hearing sensitivities, the ontogenetic development of sound communication has never been investigated. We analysed the ontogeny of the auditory sensitivity and vocalizations in the mochokid catfish Synodontis schoutedeni. Mochokid catfishes of the genus Synodontis are commonly called squeakers because they produce broadband stridulation sounds during abduction and adduction of pectoral fin spines. Fish from six different size groups - from 22 mm standard length to 126 mm - were studied. Hearing thresholds were measured between 50 Hz and 6 kHz using the auditory evoked potentials recording technique; stridulation sounds were recorded and their sound pressure levels determined. Finally, absolute sound power spectra were compared to auditory sensitivity curves within each size group. Results The smallest juveniles showed the poorest hearing abilities of all size groups between 50 and 1,000 Hz and highest hearing sensitivity at 5 and 6 kHz. The duration of abduction and adduction sounds and the pulse period increased and sound pressure level (in animals smaller than 58 mm) increased, while the dominant frequency of sounds decreased with size in animals larger than 37 mm. Comparisons between audiograms and sound spectra revealed that the most sensitive frequencies correlate with the dominant frequencies of stridulation sounds in all S. schoutedeni size groups and that all specimens are able to detect sounds of all size groups. Conclusions This study on the squeaker catfish S. schoutedeni is the first to demonstrate that absolute hearing sensitivity changes during ontogeny in an otophysine fish. This contrasts with prior studies on two cypriniform fish species in which no such change could be observed. Furthermore, S. schoutedeni can detect conspecific sounds at all stages of development, again contrasting with prior findings in fishes.

Catfish possess a high diversity in accessory hearing structures, hearing sensitivities, and sound‐generating mechanisms. Nevertheless, the ontogeny of their hearing and sound communication remains unknown. We investigated the development of Weberian ossicles and hearing sensitivity in the African bullhead catfish from postlarval stages up to adults and also examined the ontogenetic development of hearing and sound production in the yellow marbled squeaker catfish. In the smallest bullhead catfishes, the Weberian ossicles and interossicular ligaments are not fully developed. They are unable to detect sounds at low levels and high frequencies. In later stages of both species tested, hearing sensitivity increases with size at low frequencies and decreases at high frequencies. In the squeakers, the duration of stridulation sounds, sound pressure level, and pulse period increase, whereas the dominant frequency decreases with size. The most sensitive frequencies correlate with the dominant frequencies of strid...