Regulation of in vitro and in vivo T cell activation by CD43

Accessory molecule interactions can be critical in determining the outcome of a T cell's encounter with antigen. Cell adhesion proteins may augment T cell responses by facilitating TCR engagement of the antigen-MHC complex, while co-stimulatory molecules may deliver distinct signals that modulate T cell responsiveness. CD43 (leukosialin, sialophorin) has been suggested to influence cell activation by steric hindrance based upon the large size and glycosylation of the protein, as well as the relative abundance of the protein on the cell surface. In this paper we examine both in vitro and in vivo T cell-dependent responses in CD43-deficient mice. We demonstrate that T cells from CD43-deficient mice are hyper-responsive following both in vivo and in vitro activation, and that this is observed in response to not only TCR-CD3-mediated stimulation, but also following receptor-independent activation. This data suggests that mechanisms other than non-specific steric hindrance are important in the regulation of T cell activation by CD43.      

Quantitative assessment of circulating antigens in human lymphatic filariasis: a field evaluation of monoclonal antibody-based ELISA using blood collected on filter strips

objective   To quantify circulating antigens in individuals with lymphatic filariasis by means of an ELISA using blood on filter strips. method   Circulating antigens in filarial patients and normal individuals living in an area endemic for W. bancrofti infection in Madras, India were estimated using a monoclonal antibody-based ELISA. results   All microfilaraemics showed positivity to circulating antigens whereas people with chronic pathology and 80% of the endemic normals tested negative. The antigen levels in the blood collected in the night and during day time showed positivity and there was no difference in the antigen concentration. The results of the antigen levels collected onto filter strips correlated with their corresponding plasma antigen levels ( r = 0.83). In microfilaraemics, DEC treatment did not alter the levels of circulating antigens for up to one month. conclusions   We conclude that this monoclonal antibody-based ELISA using filter strips may be used in day time and replace the existing routine night blood surveys in our endemic area in India.     

A study of external skeletal fixation systems for unstable pelvic fractures

This study was undertaken to determine the feasibility of constructing an anterior pelvic external fixator capable of resisting displacement of vertical shear fractures. Newly designed tapered thread pins for cancellous bone had better bone pin fixation and their greater 6-mm diameter provided more than twice the stiffness of Hoffmann 4-mm pins when tested in clusters. Using these pins and a more rigid anterior frame as one model, various pelvic fixators were tested to determine their resistance to vertical shear forces. These tests determined that this new fixator was 16 times stiffer than a Bonnel single anterior frame and five times stiffer than a double anterior frame (both constructed of Hoffmann components). Extrapolation from the data shows that 13 mm of posterior fracture displacement would occur with loads of one half body weight using the new fixator. Additionally it was noted that Hoffmann frames constructed with two 5-mm pins performed as well as those using three 4-mm pins.     

Distribution pattern of cell bodies and fibers with neurotensin-like immunoreactivity in the cat hypothalamus

Neurotensin is widely distributed in the central and peripheral nervous systems. Extensive radioimmunoassay and immunohistochemical studies in rats show that the neurotensin immunoreactive perikarya and fibers are most prominent in the hypothalamus. Radioimmunoassay studies have suggested that the levels of neurotensin in the hypothalamus of cats may be six times higher than that of rats. We studied the distribution pattern of neurotensin immunoreactivity within the hypothalamus of the cat by avidin-biotin modification immunohistochemical methods: (1) to define its distribution pattern within the hypothalamus, and (2) to compare our findings with the patterns that have been described in rats. Results show that neurotensin immunoreactive cell bodies and fibers are most prominent in the rostral and intermediate regions of the cat hypothalamus. Cell bodies with neurotensin-like immunoreactivity are seen maximally in the medial preoptic region, the infundibular nucleus, and the lateral hypothalamus. The neurotensin positive fibers are dense in the periventricular regions of the entire rostro-caudal extent of the hypothalamus. This pattern of distribution of neurotensin immunoreactivity is similar to that described in rats. The suprachiasmatic nuclei of the cat hypothalamus, however, contained a significant number of neurotensin immunoreactive cell bodies, an observation not noted in the rat hypothalamus. The neurotensin immunoreactive neurons were more numerous in the lateral hypothalamus than has been reported in rats, but the paraventricular nucleus of the hypothalamus in cats contained fewer neurotensin immunoreactive perikarya. The presence of neurotensin immunoreactive perikarya in the suprachiasmatic nucleus and the apparent increase in the number of neurotensin immunoreactive neurons in the lateral hypothalamus may account for the increased levels of neurotensin reported in cats. Neurotensin has been speculated to play a role in nociception, thermoregulation, and control of arterial pressure by acting as a hormone or a neurotransmitter. Details of the pattern of colocalization of neurotensin with that of other neuropeptides and neurotransmitters will aid in our understanding of its role in these functions.     

Relationship between acrosome reaction and in vitro fertilization of zona-free hamster eggs by bonnet monkey (Macaca radiata) spermatozoa

The relationship between acrosome reaction, as studied by FITC-RCA staining technique, and the penetration of bonnet monkey spermatozoa into zona-free hamster eggs was investigated. The acrosomes of unreacted spermatozoa fluoresced, whereas those of acrosome-reacted sperm did not fluoresce owing to decreased binding of the lectin. The percentage of acrosome-reacted sperm increased following 3 h of incubation in BWW medium. The assessment of acrosome reaction by the FITC-RCA staining technique correlates well with the in vitro fertilization of zona-free hamster eggs.