Urban expansion and the loss of prime agricultural lands in Puerto Rico.

In many countries where the economy has shifted from mainly agricultural to industrial, abandoned agricultural lands are lost to urbanization. For more than 4 centuries the Puerto Rican economy depended almost entirely on agriculture, but sociopolitical changes early in the 20th century resulted in a shift to industry. This shift in the economy, and an increase in population, has resulted in an increase in urban areas. This study describes the rate and distribution of urban growth on the island of Puerto Rico from 1977 to 1994 and the resulting influence on potential agricultural lands. Urban extent and growth were determined by interpreting aerial photographs and satellite imagery. The 1994 urban coverage was combined with a soil coverage based on agricultural potential to determine the distribution of urban areas relative to potential farmlands. Analyses showed that in 1977, 11.3% of Puerto Rico was classified as urban. After 17 years, urban areas had increased by 27.4% and urban growth on soils suitable for agriculture had increased by 41.6%. This represents a loss of 6% of potential agricultural lands. If this pattern of encroachment by urban growth into potential farmlands continues, Puerto Rico's potential for food production in the future could be greatly limited.

Hemolytic and elastolytic activities influenced by iron in Plesiomonas shigelloides.

The aim of this study was to determine the presence of hemolytic and elastolytic enzymes in several strains of Plesiomonas shigelloides in relation to the availability of iron in culture media. Hemolytic activity and elastolytic activity were detected in strains of P. shigelloides and were enhanced when the strains were grown in an iron-depleted medium and lost after thermal treatment at 100 degrees C for 10 min. Also, elastolytic activity was inactivated by phenylmethyl sulfonyl fluoride, an inhibitor of serine proteases. Hemolytic activity was detected extracellularly in cell-free supernatants, whereas elastin degradation activity was cell associated. Both activities may be related to the virulence of P. shigelloides.

Factors affecting spoilage microflora succession on lamb carcasses at refrigeration temperatures.

Three bacterial groups were detected during the shelf-life of lamb carcasses stored at refrigeration temperatures: coryneforms (mostly Brochothrix thermosphacta), Gram-positive cocci (staphylococci) and Gram-negative bacilli (Pseudomonas spp. and Moraxella spp.). Influence of categorical variables such as sampling day, sampling area and sampling method on their recovery was analysed by a chi-square test of independence and loglinear analysis. Hierarchical loglinear modelling proved to be very useful as several three-way interactions of factors were observed.

Small noncleaved cell lymphoma in adults: superior results for stages I-III disease.

Small noncleaved cell lymphoma (SNCCL), a rare lymphoma in adults, is associated with not only a rapid complete response (CR) to chemotherapy but also with the potential to rapidly relapse both systemically and in the CNS. We treated 44 assessable adults with two similar protocols, consisting of three sequential chemotherapy combinations and intrathecal prophylaxis with methotrexate and cytarabine. The overall CR rate was 80%; it was 100% in patients with Ann Arbor (AA) stages I-III disease and 57% in those with stage IV disease. The overall survival (OS) rate at 5 years was 52%. The overall 5-year freedom from tumor mortality (FTM) rate was 63%; it was 95% for patients with AA stages I-III disease, and 29% for those with stage IV disease. Stepwise multivariate analysis of factors associated with remission duration and survival indicated that advanced-disease stage and age of 40 years or over were predictors of poor prognosis. Twelve patients with positive human immunodeficiency virus (HIV) serology were also included in this series. They had an 83% CR rate and an 83% 5-year FTM, but only a 36% 5-year OS; most deaths were secondary to opportunistic infection. Histologic subtype (Burkitt's lymphoma [BL] or non-Burkitt's lymphoma [NBL]) did not correlate with patient age, site of tumor presentation, response to therapy, or survival. Both protocols achieved comparable results. The approach used in these protocols is highly effective for patients with early staged disease, regardless of their HIV status; however, better therapy is necessary for those with SNCCL presenting in an advanced stage.