The effect of dimethylarsenics on the pulmonary tumorigenesis initiated by 4-nitroquinoline 1-oxide (4NQO) in mice was examined. The exposure of mice to dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenics in mammals, resulted in not only promotion but also progression of the tumorigenic process in the lungs of mice administered 4NQO. Furthermore, dimethylarsenics influenced the differentiation process in lung tumorigenesis by 4NQO. These results may pave the way for the elucidation of lung carcinogenesis caused by arsenics.
Objective To determine the expression of CD34 (to evaluate vascularity) and Ki-67 (as a proliferative index) in a variety of phaeochromocytomas and thus assess the utility of these markers as possible predictors of malignancy. Patients and methods Deparaf®nized tissue sections from 21 patients with benign and four with malignant phaeochromocytoma were assessed immunohistochemically to evaluate microvascular counts (using CD34 antigen) and the proliferative index (Ki-67 antigen, monoclonal antibody MIB-1).Results There was no statistical association between high microvascular counts and malignancy, but there was between the MIB-1 score and malignancy (P<0.001). Conclusions A high MIB-1 score in phaeochromocytoma suggests malignant behaviour in the component cells.The MIB-1 score may be a useful indicator for diagnosing malignant phaeochromocytoma.
This paper presents a new wet etching technique for micromachining called single-step electrochemical etching for micro structures (SEEMS), which is based on electrochemical etching in hydrofluoric acid. During the etching, the shape of the etched structure can be controlled by changing the light intensity. Several problems involved in the SEEMS process had to be solved. The two main problems are, firstly, that over-etching can be seen at the clamping point of the free standing beam and, secondly, it is difficult to remove large areas. These problems can be considerably reduced by an improved mask layout and a perforated mass supported by a single cantilever can be achieved. In addition, a new initial pit formation is demonstrated to make structures which are free from crystal orientation of silicon substrate.
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