Differential localization of Acid-sensing ion channels 1 and 2 in human cutaneus pacinian corpuscles.

Acid-sensing ion channels (ASICs) are the members of the degenerin/epithelial sodium channel (Deg/ENaC) superfamily which mediate different sensory modalities including mechanosensation. ASICs have been detected in mechanosensory neurons as well as in peripheral mechanoreceptors. We now investigated the distribution of ASIC1, ASIC2, and ASIC3 proteins in human cutaneous Pacinian corpuscles using immunohistochemistry and laser confocal-scanner microscopy. We detected different patterns of expression of these proteins within Pacinian corpuscles. ASIC1 was detected in the central axon co-expressed with RT-97 protein, ASIC2 was expressed by the lamellar cells of the inner core co-localized with S100 protein, and ASIC3 was absent. These results demonstrate for the first time the differential distribution of ASIC1 and ASIC2 in human rapidly adapting low-threshold mechanoreceptors, and suggest specific roles of both proteins in mechanotransduction.

New chromosomal regions with high-level amplifications in squamous cell carcinomas of the larynx and pharynx, identified by comparative genomic hybridization.

Squamous cell carcinomas of the head and neck generally exhibit complex karyotypes. To gain better knowledge of the changes in the subgroup of laryngeal and pharyngeal squamous cell carcinoma, chromosomal gains and losses were investigated in 42 predominantly late-stage tumours, using comparative genomic hybridization. On average, 11.2 gains and 6.8 losses were found. Gains were detected in high frequencies at 1q, 3q, 5p, 7q, 8q, 11q13, 17q, and 18p, and losses at 3p, 4p, 5q, 11qter, and 18q. Neither the number nor the type of abnormalities, nor the occurrence of specific chromosome changes, was found to be related to DNA ploidy, tumour stage, or degree of differentiation. Apart from low-level gains, many high-level amplifications were identified, in particular 3q24-qter (15 cases). Other regions recurrently involved were 11q13 (7 cases), 18p (5 cases), 18q11.2 (4 cases), and 8q23-24 and 11q14-22 (3 cases). Many of these amplified regions have not been reported before. Over half of all loci harbour genes coding for growth factors and growth factor receptors, suggesting an important role for such genes in squamous cell tumourigenesis and in the progression of late-stage tumours.

Comparative flow cytometric analysis of DNA-bound PCNA and DNA content as estimators of S-phase cells in cell cultures.

Flow cytometric estimations of S-phase cells were carried out on cultures from three different cell lines and in frozen aliquots. A PCNA-extraction protocol was applied. Measurements of the S fraction estimated from bivariate PCNA/DNA analysis after detergent extraction of DNA non-bound PCNA were compared with those obtained from total DNA histograms (Vindelöv and Christensen's technique, methanol-fixed whole cells and PCNA-extracted nuclei). No significant differences between methods, or between fresh and frozen specimens, were found in the measurements of the percentage of S-phase cells. Nevertheless, nuclei yield following PCNA extraction was highly variable, ranging from 63% to 10% (mean: 26%). In some cases, the extraction was not complete and samples had to be discarded. Usually, boundaries between S-phase events and G0/G1 or G2/M subpopulations were not clearly defined. Because of these shortcomings, and the fact that is more costly and time consuming, the estimation of the S-phase fraction by means of bivariate DNA-bound PCNA/total DNA flow cytometric studies does not seem to surpass that obtained from standard DNA cell cycle analyses.