Machine learning for science: state of the art and future prospects

Recent advances in machine learning methods, along with successful applications across a wide variety of fields such as planetary science and bioinformatics, promise powerful new tools for practicing scientists. This viewpoint highlights some useful characteristics of modern machine learning methods and their relevance to scientific applications. We conclude with some speculations on near-term progress and promising directions.

Expression of colorectal carcinoma-associated antigens in colonic polyps

Immunohistologic techniques were used to study the expression of colorectal carcinoma-associated antigens in colonic polyps and to compare this with expression in the normal colonic epithelium. Forty-nine polyps were studied using monoclonal antibodies to 16 different blood group and differentiation antigens and carcinoembryonic antigen epitopes. With the Lewis(a) antigen and the two epitopes of CEA recognized by 3D6 and COL-4 expression in polyp tissue was the same as that in the normal colon. Five types of alteration of antigen expression in polyps were seen. The blood group antigens A, B, and Lewis(b), which are expressed only on the right side of the normal adult colon, were detected in both neoplastic and nonneoplastic polyps from the distal colon. The Lewis(x) antigen and the antigen epitopes detected by the antibodies COL-12, CA19-9, ME491, and GA73.3 showed an increased frequency of expression in all types of polyps in comparison with the normal colonic epithelium, while H-type 2, ND4, and the antigen epitope detected by CO29.11 showed a slightly decreased frequency of expression in polyp tissue. The X-like antigen which was expressed in only 7% of normal colon specimens showed increased frequency of expression in polyp tissue with significantly greater expression in neoplastic than hyperplastic lesions (P = 0.003). The TAG-72 antigen was detected only in adenomas with severe dysplasia (P = 0.01), correlating well with premalignant histology. These findings have helped us clarify the variation of antigen expression in colonic polyps and allowed us to define which antigens are worthy of further investigation as markers of possible malignant transformation.

Immunohistochemical analysis of small cell tumors of the thyroid gland: an Eastern Cooperative Oncology Group study

The majority of small cell anaplastic tumors of the thyroid gland are generally believed to be non-Hodgkin's lymphomas, including most of those formerly classified as small cell carcinomas. Using a panel of antibodies capable of detecting epithelial, neuroendocrine, and B and T cells in paraffin-embedded tissue sections, we studied 68 thyroid neoplasms in which the original diagnosis was small cell carcinoma or lymphoma. Sixty-three of the tumors were identified as lymphomas of B-cell origin on the basis of L26 reactivity used in conjunction with light chain restriction and MB2 immunostaining. Two additional tumors were classified as lymphomas of indeterminate phenotype. Immunophenotyping indicated an epithelial origin in the remaining three tumors. No cases of medullary carcinoma were detected by immunostaining. Histologic review revealed a predominance of large cell and immunoblastic lymphomas, with low-grade lymphomas of mucosa-associated lymphoid tissue histology accounting for only five cases. Our findings indicate that the majority of small cell anaplastic tumors of the thyroid are B-cell lymphomas. Although primary small cell carcinoma of the thyroid may rarely occur, this diagnosis should not be made without immunohistologic confirmation.

Immunohistochemical localization of human immunodeficiency virus p24 antigen in placental tissue

As human immunodeficiency virus (HIV) infection spreads into the heterosexual population, perinatally acquired HIV infection will increase in incidence, and knowledge of the mechanism of this transfer is important. We have used immunoperoxidase techniques to detect HIV p24 antigen in formalin-fixed, paraffin-embedded placental tissue from nine known HIV serologically positive mothers. In four of these cases we have detected evidence or viral antigen in placental Hofbauer cells, vascular endothelium, or intermediate trophoblast. The implications for understanding the mode of transfer of infection to the fetus are discussed.

Detection of the tumor-associated glycoprotein antigen (TAG-72) in premalignant lesions of the colon

We used monoclonal antibody B72.3 to study the expression of the colorectal carcinoma-associated antigen TAG-72 in premalignant colonic lesions with the immunoperoxidase technique. This antigen, which is rarely detectable in the normal colonic epithelium, was expressed in 13 of 19 adenomas with moderate to severe dysplasia and nine of nine cases of inflammatory bowel disease. The antibody reacted with the normal-appearing mucosa adjacent to a carcinoma in 10 of 12 cases, although only eight of the tumors expressed the antigen. The expression of the TAG-72 antigen in the colonic epithelium may be an early marker of malignant transformation.