Functional limitation pathways and transitions in community-dwelling older persons.

The focus of this article is to determine the probability of making transitions through various ADL limitation levels, controlling for gender, age, and baseline ADL level, and using death as a competing outcome. We use the four waves of the Longitudinal Study of Aging and categorical data techniques to model the probability of these transitions. We find much heterogeneity among the transitions, with significant age and functional limitation effects. We also find that death and functional limitations are not necessarily highly linked.

Complement-like activity in the sea star, Asterias forbesi.

The coelomic fluid (CF) of Asterias forbesi was examined for the presence of complement-like activity. Cell-free CF contains hemolytic activity for unsensitized rabbit erythrocytes (E) but not unsensitized or antibody-coated sheep E. Target E sensitivity is not dependent upon phylogenetic proximity of erythrocyte species to Asterias. The activity is optimally assayed at 25 degrees C, has a sigmoidal dose-response curve, and is heat-sensitive (56 degrees C). The activity is divalent cation dependent, although Ca++ and Mg++ are not required. Nonlytic CF does not contain an inhibitor; rather, combining nonlytic and lytic CFs results in an increase in hemolysis. Activity can be consumed by treatment with zymosan, pronase, trypsin, and PMSF. Enzymatic desialidation converts sheep E into activators of the hemolytic pathway. No phospholipase activity is present in CF. Biological function is demonstrated by bactericidal activity against Vibrio tubiashii by lytic CF. These results suggest that a primitive complement system is operating in Asterias.

Antibiotics and human defence mechanisms: the effects of ampicillin and cefotaxime on intra- and extracellular killing of Salmonella enteritidis.

In-vitro reaction mixtures were set up containing bacteria, human serum, human neutrophils and ampicillin or cefotaxime at the MIC, MIC/2 or MIC/4. Serum was untreated, heat-inactivated, absorbed or both. Five indices measuring intra- and extracellular killing were calculated and the effects of heat-labile and absorbable serum factors and of the various concentrations of antibiotics on these indices were calculated. Both heat-labile and absorbable factors enhanced intra- and extracellular killing; antibiotics had a similar effect except that phagocytosis was reduced. Antibiotics at MIC/4 exerted as great an effect as did higher concentrations and this was especially so for cefotaxime. Both heat-labile and absorbable serum factors had a greater effect on all five indices the lower the concentration of antibiotic with advantage for cefotaxime. In the presence of immunological serum factors the overall effect against Salmonella enteritidis is maintained as the concentration of antibiotic falls below the MIC and this is especially seen in the presence of cefotaxime.

Response of cultured human brain tumors to nitrosoureas: correlation with clinical data.

An in vitro microcytotoxicity assay was utilized to determine the sensitivity of 58 cultured human malignant gliomas to the chemotherapy agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Of 58 such tumors, 42 (72%) showed a statistically significant cytotoxic response to BCNU in this assay. For those responding tumor lines, the cytotoxic index ranged from 0.25 to 0.76, with most clustered at the 0.40 level. To determine the therapeutic predictive relevance of such microcytotoxicity testing, the clinical course of patients receiving postoperative radiation therapy plus two or more doses of nitrosourea chemotherapy, as well as two or more computerized tomographic scans, was evaluated. In the 14 patients meeting all these criteria, tumor size increased in all five patients whose tumors did not respond to BCNU in the microcytotoxicity test. Six of the nine patients whose tumors in culture showed significant sensitivity to BCNU in vitro showed a clear decrease in tumor size over periods ranging from 17 to 48 months. Tumors in two patients increased in size, and one remained unchanged over the interval studied. These data support the concept that in vitro microcytotoxicity testing can be predictive of clinical response. Further study of this correlation seems warranted.

Effects on pulp and dentin of iontophoresis of sodium fluoride on exposed roots in dogs.

Experiments were performed on young permanent teeth in which there was demonstrable active dentin formation. Following surgical exposure of roots and removal of cementum with scalers, 1 percent sodium fluoride in aqueous solution was applied either topically or with direct-current iontophoresis. Two levels of current, therapeutic or five times therapeutic, were used. Observation periods were 7 and 80 days. There were no demonstrable histologic or ultrastructural alterations of the underlying pulp; nor was there a resultant change in the rate of dentin formation. While exposure of root surface dentin alone (negative control) produced no alterations, grinding the surface (positive control) caused noticeable changes in dentin, odontoblasts, and pulp.

Histochemical identification of myosinlike substance in cells of the human dental pulp.

In this study of the human dental pulp, substances were found in smooth muscle cells, myoendothelial cells, fibroblasts, and odontoblastic processes that demonstrate staining and extraction characteristics identical to myosin in muscle. It is concluded that the myosinlike material similar to that found in cells elsewhere in the human also occurs in cells of the dental pulp.