Fc-receptor heterogeneity of human suppressor T cells.

Concanavalin A (Con A) stimulated the IgM-binding subpopulation of human T cells (TM) to suppress the pokeweed mitogen-induced differentiation of B lymphocytes to plasma cells. Control TM cells that had not been Con A activated did not suppress. The degree of suppression was related to the number of Con A-TM cells added to the cultures and it was abolished by irradiation of the T lymphocytes either before or after the 24-hr culture period with Con A. Suppression did not require the presence of TG cells, whose suppressor potential has been previously established. These findings indicate that suppressor activity is not confined to the TG subpopulation but may be expressed by TM cells also.     

Levels of citation of nonhuman animal studies conducted at a Canadian research hospital

The publication of scientific articles that receive few or no citations raises questions of the appropriate use of resources as well as ethics. In the case of animal research, the ethics issue extends beyond human patients to nonhuman animals, as the research subjects them to pain and, typically, to death. This study is a citation analysis of animal research conducted at Toronto's Hospital for Sick Children (HSC). Of the 594 publications (1990 to 1995) on animal research by affiliates of HSC, 29% received fewer than 10 citations in a 10-year period. We compare the research history of 13 “best ”and 13 “worst ”HSC scientists. Worst researchers continue to do infrequently cited research. Recommendations indicate how institutions and researchers can become more effective and accountable.     

Productivity and grazing impact of Oikopleura dioica (Tunicata, Appendicularia) in Tokyo Bay

To estimate the productivity and grazing impact of a commonappendicularian species Oikopleura dioica in Tokyo Bay, monthlyobservations on its abundance and vertical distribution wereconducted during 2000. The abundance peaked in February andOctober, but was low during summer. Seasonal fluctuations inproductivity were similar to those of the abundance, with maximumvalues of 92, 134 and 508 mg C m^–2 day^–1 for somatic,new house and discarded house productivity in October and 206mg C m^–2 day^–1 for fecal pellet productivity inFebruary, respectively. The averaged biomass of O. dioica wasonly 2.5% of that of copepods; however, the secondary productivityof the former corresponded to 12.4% of the latter. Daily grazingimpact on particulate organic carbon ranged from 0.05% to 5%,which is close to the impact by copepods. These results implythat in Tokyo Bay, where small copepods and jellyfish are abundant,O. dioica is an important component of the ecosystem becauseit bridges between small primary producers and higher consumers.     

The walking gaits of some species of Pecora

A method is presented for defining the walking gaits of quadrupeds from films so that they can be compared in closely related species. Differences in walking patterns of 18 pecoran species belonging to four families are discussed with respect to anatomy and environment. Variation in the walk patterns of members within a species are assessed. They are found to vary often with the speed at which the walk is executed, with the terrain, with the presence of heavy horns or antlers and with age. The time taken for one walking stride increases with the increase in length of the legs, but the legs swing forward more rapidly than they would if they acted passively like cylindrical pendulums.     

Ingestion of phytoplankton by the micro- and mesozooplankton communities in a productive subtropical estuary

Grazing on phytoplankton by the micro- and mesozooplankton communitieswas measured during four cruises in a shallow (1.5 m) productive(up to 6 g C m^–2 day^–1 estuary in the northern Gulfof Mexico. Grazing-induced mortality on phytoplankton was alwayshigh and >95% of the grazing was by the microzooplanktoncommunity The grazing contribution from the mesozooplanktoncommunity, comprised primarily of Acartia tonsa, is believedto be small because populations were kept low by predation andadvective losses. A simple model is developed to describe phytoplankton-zooplanktoninteractions in this estuary. Attempts to understand the distributionand abundance of phytoplankton in estuaries must include estimatesof grazer-induced mortality on the phytoplankton.     

Cross-reactive T-cell antigens among mammalian species.

Fluoresceinated heteroantisera prepared against T cells of rats, monkeys, and humans were reacted withthymus and spleen cells from 11 selected species. These reagents recognized cross-reacting T cell antigen(s) among rodent species (mouse, rat, guinea pig, and hamster) and among primate species (monkey and humans). With one exception, the cross-reactivity was restricted to a phylogenetic order. All three antisera required relatively few absorptions to achieve T cell specificity for related species when compared to absorption requirements for the isologous species. Differentiation antigens within a phylogenetic order thus appear to be more homologous than other cell surface constituents on T cells.     

Recurrent aphthae: treatment with vitamin B12, folic acid,and iron.

A series of 130 consecutive outpatients with recurrent aphthous stomatitis were screened at the oral medicine department, Glasgow Dental Hospital, for deficienciesin vitamin b12, folic acid, and iron. In 23 patients (17.7%) such deficiencies werefound; five were deficient in vitamin B12, seven in folic acid, and 15 in iron. Four had more than one deficiency. Out of 130 controls matched for age and sex 11 (8.5%) were found to have deficiencies. The 23 deficient patients with recurrent aphthaewere treated with specific replacement therapy, and all 130 patients were followed up for at least one year. Of the 23 patients on replacement therapy 15 showed complete remission of ulceration and eight definite improvement. Of the 107 patientswith no deficiency receiving local symptomatic treatment only 33 had a remission or wereimproved. This difference was significant (P less than 0.001). Most patients withproved vitamin B12 or folic acid deficiency improved rapidly on replacement therapy;those with iron deficiency showed a less dramatic response. The 23 deficient patientswere further investigated to determine the cause of their deficiencies and detect the presence of any associated conditions. Four were found to have Addisonian perniciousanaemia. Seven had a malabsorption syndrome, which in five proved to be a gluten-induced enteropathy. In addition, there were single patients with idiopathic proctocolitis, diverticular disease of the colon, regional enterocolitis, and adenocarcinoma of thecaecum. We suggest that the high incidence of deficiencies found in this series andthe good response to replacement therapy shows the need for haematological screening of such patients.