[Detection of p53 mutation using PCR-SSCP silver staining method]

A simple and sensitive technique to detect point mutation of the p53 gene using silver staining method for single-strand conformation polymorphism analysis of polymerase chain reaction (PCR-SSCP) is reported. In this study, the aberrations of the p53 gene (exon 6-8) in clinical specimens of primary cervical carcinoma were examined. Of 27 tumor tissues 2 samples showed mutations of p53 exon 7. Absence of abnormal bands in the p53 exon 6-8 in all ten normal cervical tissues. It appears that inactivation of p53 gene by point mutation is infrequent in clinical samples of human cervical carcinomas.

Analysis and synthesis of a class of discrete-time neural networks with multilevel threshold neurons

In contrast to the usual types of neural networks which utilize two states for each neuron, a class of synchronous discrete-time neural networks with multilevel threshold neurons is developed. A qualitative analysis and a synthesis procedure for the class of neural networks considered constitute the principal contributions of this paper. The applicability of the present class of neural networks is demonstrated by means of a gray level image processing example, where each neuron can assume one of sixteen values. When compared to the usual neural networks with two state neurons, networks which are endowed with multilevel neurons will, in general, for a given application, require fewer neurons and thus fewer interconnections. This is an important consideration in VLSI implementation.

Prevalence of human papillomavirus DNA sequences in an area with very high incidence of cervical carcinoma

To improve our understanding of the relationship and possible associations between human papillomavirus (HPV) infection and the development of cervical malignancies, the presence of multiple types of HPV DNA sequences in cervical carcinoma was determined in Chinese citizens living in two different geographical locations where the incidences of cervical carcinoma are either relatively low or extremely high. HPV DNA sequences were found in 88.5% (54 of 61) of Chinese cervical carcinoma patients living in Taiwan, where the prevalence of cervical carcinoma is 23.7 per 100,000 women. In contrast, in LueYang in Shanxi province, an area with a very high prevalence of cervical carcinoma (1,026 per 100,000 women), only 57.1% (28 of 49) of Chinese cervical carcinoma patients were found to be infected with genital HPV. This result seems to suggest that either the presence of HPV may have different implications in different populations or HPV infection may not be the only factor that determines the development of cervical carcinoma, at least in certain geographical areas. Recently acquired transient or chronic persistent HPV infection may have a different outcome with regard to cervical carcinogenesis. Alternatively, other factors, such as host determinants, may play a role in the development of cervical carcinoma.

[Study of histopathological and ultrastructural differences between condylomata acuminata and pseudocondyloma of vulvae]

Histopathological alterations of condylomata acuminata were characterized by hyperkeratosis, parakeratosis, acanthosis, elongation of the rete ridges, pseudoepitheliomatous hyperplasia, discrete or grouped koilocytes, proliferation and dilatation of dermal capillaries, lymphocytic and histocytic infiltration around dermal capillaries. Histopathological pattern of pseudocondyloma of vulvae were characterized by finger-shaped configuration, epithelium was similar to normal of mucous membrane without atypia. The lesion was composed of a rich vascular network surrounded by connective tissue and a mild lymphocytic infiltration. Ultrastructural alterations of condylomata acuminata were characterized by proliferation of basal cells, enlarged and swollen nuclei in all layers, 1-4 large nucleoli, 1-3 nuclear bodies, interchromatin granules and perichromatin granules in some proliferating nuclei, swollen mitochondria, dilated endoplasmic reticulum, and dissolved glycogen. Ultrastructural alterations of pseudocondyloma of vulvae were characterized by proliferation of mucomembranous epithelial cells, mild swollen nuclei, 1-2 nucleoli, no nuclear body interchromatin and perichromatin granule, the dilatation of interstitial capillaries, and abundant fibril bundles in the dermis. Thus, the histopathological and ultrastructural manifestations of condylomata acuminata and pseudocondyloma of vulvae were significantly different. It may be of help in differentiation between the two disease.

The best approximation to C(2) functions and its error bounds using regular-center Gaussian networks

Gaussian neural networks are considered to approximate any C(2) function with support on the unit hypercube I(m)=[0, 1](m) in the sense of best approximation. An upper bound (O(N(-2))) of the approximation error is obtained in the present paper for a Gaussian network having N(m) hidden neurons with centers defined on a regular mesh in I(m).

[Molecular and ultrastructural study on the relationship between human papillomavirus and female genital condyloma in China]

From the results of DNA hybridization, it has been shown that there is a close relationship between HPV 16 and human uterine cervical carcinoma in China, and also that the viral DNA is integrated into the cancer cell genome. Genital condyloma revealed a high positive hybridization rate with HPV 11 DNA, and the viral DNA presented as an episome apart from the cell genome. Under the electron microscope, the inter and perichromatin granules as well as nuclear bodies were observed in all biopsies with positive hybridization, but no HPV particle was found in cancer cells, besides these two kinds of chromatin granules. Human papillomavirus nucleocapsid particles were observed in the nuclei of some genital condyloma cells. Electron-dense matrix aggregates of different sizes were seen in the perinuclear cytoplasm and in the nuclei. This kind of structure may be related to the process of HPV maturity, but its nature remains to be studied.