CD5+ B-cell networks.

The relationship between precursors for B1 and B2 cells remains controversial. On the basis of recent experimental results, it is highly probable that B1 cells can be generated from the same sources as B2 cells. However, the precursor cell types involved, the microenvironment and the age of donor and recipient may all determine whether B1 cells are generated under the variety of experimental conditions that have been described in the literature.

Evaluation of collagen cross-linking techniques for the stabilization of tissue matrices.

The use of glutaraldehyde (GTA) for cross-linking biological tissue implants has a number of undesirable side effects, including cytotoxicity and induction of calcification. In an attempt to find an improved cross-linking agent for tissue implants, we have evaluated a number of cross-linking procedures shown previously to be effective with pure collagen or collagenous substrates, including GTA, succinic anhydride, cyanamide, 1-ethyl-3-(dimethylaminopropyl)carbodi-imide, dimethyl suberimidate, ascorbate-copper, glucose-lysine and acyl azide treatments. Apart from GTA, only acyl azide treatment significantly cross-linked human dermis, the degree of cross-linking being better than that seen after treatment of dermis with 1 mM GTA.

Ethylene oxide sterilisation of allogenic bone implants.

We have evaluated the ability of ethylene oxide gas to penetrate bone matrices and subsequently kill a defined microbiological load. These experiments demonstrated that freeze-dried cancellous and cortical bone did not pose a barrier to the rapid diffusion of the gas. A normal cycle on a commercial ethylene oxide steriliser provided a sixfold overkill.

Characterization, specificity, and IgV gene usage of anti-lymphocyte monoclonal antibodies from perinatal mice.

Previous studies have shown that CD5+ B cells predominate during development of the immune system and frequently secrete self-reactive antibodies, some of which appear to influence the development of the adult B cell repertoire. In addition, we now show that a high frequency of perinatally derived antibodies react with lymphocytes. Hybridomas derived from perinatal liver and splenic B cells and from spleens of adult BALB/c and C57BL/6 mice were screened by immunofluorescence on thymocytes.

Identification of a surface protein (p100) associated with two glycosyl-phosphatidylinositol-linked molecules (Thy-1 and ThB) by natural anti-lymphocyte autoantibodies.

Our previous study of natural autoantibodies showed that anti-lymphocyte antibodies are frequently produced by perinatal B cells from normal strains of mice. One-third of these monoclonal antibodies (mAb) recognized similar epitopes on the surface of thymocytes. In the present report, we have characterized the molecule recognized by three of these mAb (D10, G7, 22).

The expression of the mouse VpreB/lambda 5 locus in transformed cell lines and tumors of the B lineage differentiation pathway.

The expression of RNA transcripts from two pre B lymphocyte related genes, VpreB and lambda 5, has been studied in a series of transformed cell lines which appear frozen at different states of B lineage differentiation, from early progenitors to surface Ig positive B cells. In the HAFTL-1 cell line, which arose from fetal liver by transformation with a retrovirus containing the Hras oncogene, Northern analysis of poly A+ mRNA as well as in situ hybridization of RNA in single cells revealed that lambda 5 and VpreB are already expressed at the progenitor stage and increase in expression as the progenitors differentiate to precursor (preB) cells, or are turned off as the progenitors differentiate to myeloid cells. Continued rearrangements of Ig genes in pre B cell lines leading to Ig expression on the surface of NFS-5 pre B cells do not influence the continued expression of VpreB and lambda 5.

Performance measures, blood lactate and plasma ammonia as indicators of overwork in elite junior weightlifters.

The effects of short-term overwork on performance measures, blood lactate, and plasma ammonia concentrations were examined in 28 elite junior weightlifters who participated in a 2 wk high volume resistance training camp. Performance testing (maximum effort vertical jump test and snatch lift) and blood chemistry analyses (ammonia and lactate) were conducted before (T1) and after (T2) 7 d of high volume training (2-3 workouts/d). Blood samples were collected from an antecubital vein at rest, preexercise, 5 min postexercise, and 15 min postexercise at T1 and T2.

Idiotypic regulation of development of the B-cell repertoire.

The mouse B-cell repertoire develops from a restricted set to an extremely diverse set of specificities. Establishment of some of the B-cell clones that constitute the adult repertoire is facilitated and guided by idiotype-directed interactions among complementary sets of B cells early during ontogeny. Through in vivo experiments described here and reported elsewhere, we have shown that the program of B-cell development involving idiotypic interactions is obligatory in the development of certain B cells that provide immunity against bacterial infections.

The fetal omentum in mice and humans. A site enriched for precursors of CD5 B cells early in development.

From these studies the fetal omentum appears to be an important site of B-cell generation in humans and a source of CD5 B cells in mice. We have analyzed the fetal omentum in other species and have found that B-cell development as determined by the presence of cytoplasmic IgM+ pre-B cells is also detected in the fetal rabbit omentum. We do not know if there is bias towards the production of CD5 B cells in this species; however, these preliminary results demonstrate that this site may be conserved throughout evolution in mammals as a site of B-cell generation.

Continuous anti-interleukin 10 antibody administration depletes mice of Ly-1 B cells but not conventional B cells.

Ly-1 B cells have the distinctive property of continuous self-replenishment and, as we have shown previously, can be further distinguished from conventional B cells on the basis of greatly elevated constitutive and inducible production of the recently described cytokine interleukin 10 (IL-10). To test the possibility that IL-10 acts as either an autocrine or paracrine growth factor for Ly-1 B cells, we treated mice continuously from birth to 8 wk of age with a monoclonal rat IgM antibody that specifically neutralizes mouse IL-10. Mice treated in this way lacked peritoneal-resident Ly-1 B cells, contained greatly reduced serum immunoglobulin M levels, and were unable to generate significant in vivo antibody responses to intraperitoneal injections of alpha 1,3-dextran or phosphorylcholine, antigens for which specific B cells reside in the Ly-1 B cell subset.

Acute hormonal responses in elite junior weightlifters.

To date, no published studies have demonstrated resistance exercise-induced increases in serum testosterone in adolescent males. Furthermore, few data are available on the effects of training experience and lifting performance on acute hormonal responses to weightlifting in young males. Twenty-eight junior elite male Olympic-style weightlifters (17.

The human fetal omentum: a site of B cell generation.

The fetal mouse omentum has been shown to be a source of precursors that exclusively reconstitutes Ly1+ B cells and the closely related Ly1- sister population, but not conventional B cells or T cells. We have extended these studies to compare B cell development in the human fetal omentum, liver, and spleen, and to demonstrate that the pro/pre-B cell compartment (CD24+, sIgM-) is detected in the omentum and liver but not spleen as early as 8 wk of gestation. From 8 to 12 wk of gestation, the proportions of IgM+ cells that were pre-B cells (cIgM+/sIgM-) in the omentum and liver were 53 +/- 15% and 45 +/- 13%, respectively, and IgM+ cells were not detectable in the spleen.

Prospective randomised study of double hemi-body irradiation with and without subsequent maintenance recombinant alpha 2b interferon on survival in patients with relapsed multiple myeloma.

Immediately before first hemi-body irradiation, 59 patients with relapsed multiple myeloma were randomised to receive or not to receive subsequent alpha-2b interferon maintenance. 13 patients (22%) [8 of 31 (26%) controls, 5 of 28 (18%) in the interferon arm] received single hemi-body irradiation alone due to progressive disease and/or persistent cytopoenias following the initial procedure. Mean time between upper and lower hemi-body irradiation was 69 days (range 35-294).

The hydrodynamic function and leaflet dynamics of aortic and pulmonary roots and valves: an in vitro study.

Fresh homograft aortic and pulmonary roots were tested in a pulsatile flow simulator to assess their hydrodynamic function and leaflet opening characteristics. Simultaneous flow and pressure measurements were obtained for a range of cardiac outputs. The effective orifice area and regurgitant volumes were calculated.

Development and function of the early B cell repertoire.

The early B cell repertoire is characterized by extensive interconnectivity, autoreactivity and multispecificity. Our preliminary sequence analysis of some of the idiotype specific antibodies is beginning to provide molecular clues to explain the observed multireactivity and the expression of shared idiotypic determinants on immunoglobulins of early B cells. The VH gene rearrangements analyzed are typical of the early pre-B cell and CD5 B cell repertoire.

Hydrodynamic function of second generation porcine bioprosthetic heart valves.

The hydrodynamic function and leaflet dynamics of second generation porcine valves prepared with low- or zero-pressure fixation have been studied and compared to first generation porcine bioprostheses, bileaflet, and tilting disc mechanical valves. The Carpentier-Edwards Supra-Annular and Hancock II valves showed lower pressure drops than the Medtronic Intact valve and first generation porcine valves, and comparable overall energy losses to mechanical valves at normal cardiac outputs. Only the zero-pressure fixed Intact valve showed synchronous leaflet opening.

Cryopreservation of cultured skin cells.

Cryopreservation of human skin keratinocytes and fibroblast cells has been evaluated using three cryoprotectants at various concentrations, three cooling rates and two warming rates. Optimal combinations of factors were determined. Selection for tolerance to cryopreservation was not detected after repeated freeze/thaw cycles.

Thymus-dependent network responses to a monoclonal cross-reactive antiidiotypic antibody.

BALB/c mice were inoculated i.p. with a cross-reactive anti-Idiotypic mAb (designated FD5-1) in the absence of Ag or adjuvants.

An embryonic source of Ly1 but not conventional B cells.

Ly1+ B cells differ from conventional B cells with respect to their anatomical localization, cell surface marker expression, and antibody repertoire suggesting that they may constitute a functionally distinct subset of B cells. To determine whether Ly1+ B cells also have a developmentally distinct site of origin we grafted various fetal primordia into adult severe combined immunodeficient (scid) mice and analyzed their potential to give rise to T and B cells. We demonstrated that fetal omentum, but not spleen or thymus grafts, reconstituted exclusively Ly1 B cells (including the Ly1 sister population) as well as a population of IgM and IgA producing plasma cells in the spleen and gut, respectively.