Screening for p53 mutations in exons 5 to 8 in 124 pediatric malignancies identi®ed 18 abnormal shifts using single strand conformation polymorphism: 12 were missense mutations and in 6, no mutation was detected in the exon or in the splice donor acceptor sequences. Sequencing was then performed in the adjacent introns, revealing a G to A base substitution at 39 base pairs upstream to exon 7. This mutation was identi®ed in the germ line of ®ve of the patients, and also in the father of one, whose parents were available. For comparison, of the 184 normal controls similarly screened, only one had this mutation (P=0.036). Positive staining of p53 protein was observed in three of the para n embedded tissues that were available: brain tumor, rhabdomyosarcoma, and lymphocytes from a normal lymph node from the rhabdomyosarcoma patient. All tumors with the identi®ed intron mutation were Li-Fraumeni syndrome tumors. Sequencing of all exons including splice sites was performed and revealed no mutation. We suggest that this mutation in intron 6 of the p53 gene stabilizes the wild type p53 protein, resulting in its abnormal accumulation. Mutations in the noncoding region of p53 should be further studied.

Congenital defect of the muscular layer of the small intestine is a rare cause of spontaneous bowel perforation in premature infants. During the last 12 years we have observed four similar cases. We describe the most recent one, a premature infant who developed two abdominal events. On her 2nd day of life, spontaneous perforation of the distal ileum due to focal absence of the muscular layer occurred. Several weeks later she developed the typical clinical and histological picture of necrotizing enterocolitis. The clinical and histological characteristics of the two different conditions are compared, and the 24 cases reported in the literature are discussed. We conclude that focal absence of intestinal musculature may be not such a rare entity as is commonly believed.

Characterization of T-lymphocyte subpopulations adjacent to and infiltrating the primary tumor of breast cancer was carried out using a direct immunofluorescence procedure with the antibodies anti-(Leu-2a) for suppressor/cytotoxic (CD8+) and anti-(Leu-3a) for helper/inducer (CD4+) T-lymphocytes. Fifty-six primary malignant tumors with lymphoid infiltration were studied. The majority (58.9%) were infiltrating duct carcinoma. There were metastases to axillary lymph nodes in 6.67% of the patients. Massive lymphoid infiltration (greater than 40 lymphocytes per x 400 microscopic field) was found in 19.6% of the tumors and moderate infiltration (20-40 lymphocytes per field) in 51.8%. In all the tumors studied there was a reversed CD4+/CD8+ ratio as compared to that found in normal peripheral blood. In 66.1% the CD4+/CD8+ ratio (helper/suppressor) was less than 1.0. The reversed ratio was due to a significant decrease in the number of helper cells (P less than 0.0005). The most significant drop was in the stroma area (P less than 0.0001) as well as in the tumor tissue (P = 0.001). Of particular interest was the significant positive correlation between the age of the patients and an increased number of CD4+lymphocytes in the stroma (P = 0.02). Significant negative correlations were found between a reduced number of CD4+ lymphocytes or CD4+/CD8+ ratio and several histological parameters: tumor diameter, pleomorphism, nucleus/cytoplasm ratio. There was also a significant positive correlation between the total number of CD8+ lymphocytes infiltrating the tumor tissue and the number of axillary lymph nodes with metastatic disease (P = 0.03). It is suggested that the reversed ratio of CD4+/CD8+ lymphocytes may significantly affect the host/tumor immune surveillance.