Lymphosarcoma of the breast

Lymphoma of the female breast is rarely a primary lesion. It may be found without manifestations of the disease elsewhere in the body. The types include the reticular cell, the histiocytic, the mixed and the follicular type of lesion. Usually the disease disseminates to the other parts of the body, but should it be confined to the breast and be successfully treated, it will not develop elsewhere. Clinically, radiologically and pathologically these lesions may be misdiagnosed as carcinoma. Irradiation is the treatment of choice for lymphosarcoma and therefore mastectomy is not generally recommended and may even be contra-indicated.S. Afr. Med. J., 48, 449 (1974)

Eosinophil infiltration of the stomach

Eosinophil infiltration of the stomach or gastro-intestinal tract is an unusual condition, in which an inflammatory infiltrative condition may present as a tumorous mass simulating a malignant growth. Although the condition was first described in 1937 and a number of cases have since been reported, not a great deal is known about it. Its aetiology is obscure and its behaviour variable. Patients in whom the disease is likely to spread widely through the stomach and small intestine, and where it is likely to recur and progress, may have eosinophilia.S. Afr. Med. J. 48, 405 (1974)

OPINION Endless summer: internal loading processes dominate nutrient cycling in tropical lakes

1. Fossil diatom assemblages deposited in more than a dozen African lakes roughly 9500 years BP were dominated by a single planktonic species, Stephanodiscus astraea (Ehrcnb.) Grun. (although realistically this is likely to be a species complex). These diatoms flourished when lake-levels were maximal. Data are included from many of (he large African lakes, and others extending from Lake AbhÉ0, Ethiopia, to Lake Cheshi, Zambia. 2. Because the ecological physiology of Stephanodiscus species is well known one can predict the nutrient regime that must have existed when Stephanodiscus bloomed. Owing to competition for resources Stephano-discus species dominate when the supply ratio of silicon to phosphorus (in moles) in the epilimnion is relatively low (Si:P∼1). Consequently, lakes dominated by S. astraea are often hypereutrophic. 3. We propose a series of hypotheses to explain why tropical lakes have decreasing Si:P ratios as lake-levels increase, primarily owing to internal P-loading processes in the epilimnia. These observations appear to contradict present conceptions of the fundamental relationships governing nutrient loadings to and within lakes. Tropical lakes appear to have had increasing epilimnetic phosphorus loading as lake-levels increased. In contrast, large, deep lakes in the temperate zone are usually oligotrophic, with high Si:P ratios. 4. Our major conclusion is that regeneration rates are greater than removal rates for phosphorus in tropical lakes as compared to temperate lakes, especially where epilimnelic mixing exceeds 50 m. Biological control of the elemental cycles dominate in tropical lakes, whereas nutrient cycles in temperate lakes are dominated by physical processes for a large part of the year. This results in major differences in the fundamental mechanisms of nutrient regeneration and their relationships to morphometric features of lakes in the two regions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71789/1/j.1365-2427.1990.tb00280.x.pd