Analysis of alterations in the retinoblastoma gene and tumor grade in bone and soft-tissue sarcomas.

We examined 43 sporadic bone and soft-tissue sarcomas for molecular genetic alterations affecting the retinoblastoma susceptibility gene Rb-1 (also known as RB1). The gene was altered in 6 of 14 sporadic osteosarcomas and in 5 of 29 other bone and soft-tissue sarcomas. Rb-1 messenger RNA (mRNA) transcripts were detected in normal tissues and benign lipomas, but they were absent or altered in each of the 19 sarcomas we examined. To examine the association of deletions in the Rb-1 gene with tumor grade, we correlated the DNA alterations in the Rb-1 gene with clinical data for 36 patients. The Rb-1 gene was altered in 40% of high-grade bone and soft-tissue tumors, but not in low-grade bone tumors and in only one low-grade, soft-tissue sarcoma. Overall, 10 of 25 high-grade sarcomas had detectable alterations of the Rb-1 gene compared with only 1 of 11 low-grade tumors.

The viability of articular cartilage in fresh osteochondral allografts after clinical transplantation.

The articular cartilage of four fresh osteochondral allografts was biopsied after transplantation, and its viability was studied by autoradiography. The biopsy specimens were labeled with both 3H-cytidine, for newly synthesized ribonucleic acid, and 35S-sulphate, for newly synthesized proteoglycans. The cartilage of a lateral humeral condylar graft at twelve months had 96 to 99 per cent labeled chondrocytes, the articular cartilage of a medial femoral condylar graft at twenty-four months showed 69 to 78 per cent labeled chondrocytes, and the cartilage of a medial tibial-plateau graft at forty-one months had 90 per cent labeled cells. At six years, a lateral tibial-plateau graft had 37 per cent labeled chondrocytes.

Virus-induced osteosarcoma in rats.

An experimental model for osteosarcoma was developed in which, after Moloney murine sarcoma virus was injected into the tibial marrow space of three strains of inbred neonatal rats, a highly malignant neoplasm arose within ten days. This tumor was readily maintained in tissue culture and was transplantable to adult rats. It arose in the metaphyseal marrow of several bones, was locally invasive, metastasized to the lungs, and histologically resembled osteosarcoma.

Immunogenicity of virus-induced rat osteosarcoma.

The immunogenicity of a virus-induced rat osteosarcoma was studied utilizing the lymphocyte microcytotoxicity test. Intratibial injection of murine sarcoma virus (Moloney) resulted in the development of palpable tumors at the injection site which on histopathological examination appeared to be osteosarcomas. In 73 per cent of animals injected these tumors progressed and metastasized to the lungs. Lymphocytes from these "progressor" animals demonstrated an ability to kill osteosarcoma cells in vitro (as quantitated in the microcytotoxicity test) while serum from these animals abrogated or blocked the cell-mediated cytotoxicity. In the remaining animals the tumors either failed to develop or regressed spontaneously. Lymphocytes from these "regressor" animals also demonstrated cytolytic activity against osteosarcoma cells in vitro, but serum failed to block the lymphocyte-mediated cytolysis. Both regressor and progressor groups demonstrated humoral cytotoxic antibodies to tumor antigen on the basis of the ability of their serum to kill tumor cells in vitro.

Biology of allografting.

Allograft bone continues to play an important role in revision hip and knee arthroplasty. A basic understanding of allograft biology and immunology is important in order to increase the success of allografting. Although the literature has a wealth of knowledge on the subject there are still many unknowns. The role of immunology in bone transplantation has been known for a long time, but only recently has it become apparent that the bone remodeling system and the immunologic system interact to affect the clinical success of bone transplantation. Neither of these two systems are completely understood nor is their interaction. Future research in the field of bone transplantation will be aimed at a better understanding of these systems individually but, more important, how they interact in humans. Until that time, allografting still can be used with success if one understands the role of allograft biology, immunology, and the important role of the host environment in bone transplantation.

Bone banks and allografts in community practice.

The increasing volume of orthopaedic reconstructive procedures requiring replacement of bone stock justifies the initiation of programs of bone banking in community hospitals. Provided that strict criteria are followed to assure rigorous screening of donor bone and the reliable preservation of bone graft material, community banking is safe and cost-effective. Banked allograft bone can be used successfully in a wide variety of orthopaedic procedures performed in community hospitals. In general, the best uses are filling bone cavities, buttressing, and augmenting the quantity of autograft bone. In revision reconstructive surgery of the hip, bank bone is used to replace bone stock in protrusio, acetabular dysplasia, and proximal femoral deficiency. The best and most common indication for the use of bank bone in tumor surgery is after curettage or excision of benign lesions. Allografts may be used to reconstruct bony defects after excision of malignant tumors and in the surgical treatment of metastatic disease. These instances require larger bone bank facilities than those commonly available in a community hospital setting. Medicolegal considerations related to bone banking and the use of allografts in community practice include the regulatory requirements outlined in the UAGA, questions concerning negligence liability, and theories of strict product liability. Overall, good medical practice and obtaining informed consents will minimize legal risks related to bone banking and transplantation in a community setting.

The immune response: the afferent arm.

The key to understanding afferent immunity is the mechanism of activation of T lymphocytes by specialized antigen presenting cells, which bind antigenic peptide to Class II major histocompatibility molecules, and stimulate T cells via Signal 1 (antigen) and Signal 2 (costimulation). The best studied costimulatory pathway is the interaction of B7-1 or B7-2 ligand molecules on antigen presenting cells with CD28 or CTLA-4 receptors on T cells. T cell signaling occurs through the T cell receptor-CD3 complex and is augmented by cosignaling via CD4, CD8, and CD45. The activation of T cells to alloantigen occurs by either a direct pathway of recognition of allogenic major histocompatibility molecules (with or without an associated endogenous peptide), or by an indirect pathway of recognition of processed donor alloantigens via recipient antigen presenting cells. Afferent immunity on the musculoskeletal system is of special interest because of the absence of viable donor antigen presenting cells in processed grafts that makes them susceptible to the indirect pathway of alloantigen recognition.

Allospecific T-cell lines with functional activities.

A T-lymphocyte line and sublines from it reactive with Class II MHC alloantigens have been examined for proliferative responses and helper activity in vitro and in vivo. Both the parent cell line and its derived sublines recognize alloantigenic determinants encoded for by the I-A subregion of the H-2 complex in a proliferative assay, and have regulatory activity for allogeneic and syngeneic B cells in two different helper systems. The in vitro selected cell populations are approximately twenty-fold more active in functional helper assays than populations selected in vivo by priming. Differential analysis of the patterns of proliferative responses of sublines against allogeneic I-A molecules on different backgrounds indicates that one type of selected cells reacts preferentially to MHC molecules presented on the background used for selection.

I. Characterization of cytotoxic effector cells generated from regional lymph nodes after immunization in the footpad.

A system is described which involves an in-vivo and an in-vitro step for the generation of strong primary cytotoxic T lymphocyte (CTL) responses to multiple minor alloantigens. The protocol consists of immunizing mice in the footpad with irradiated, minor alloantigen-different spleen cells. Four days later, cells from the lymph nodes draining the site of injection are cultured for 3 days in the absence of antigen to allow the development of cytotoxic activity. The analysis of the effector phase of the response indicates that the killer cells are H-2 restricted cytotoxic cells specific for minor alloantigens. The in-vitro phase of these cytotoxic responses is T cell-dependent and the responder cells proliferate strongly during the culture period. Both cytotoxic and proliferative responses are abolished by passing responder cells over Sephadex G-10 prior to culture. The results suggest that the maturation process of CTL-precursor (CTL-P) cells into effector CTL in vitro depends upon proliferating T cells and accessory cells.

Ontogeny of priming of cytotoxic T cells to minor alloantigens: the development of direct priming precedes that of cross-priming.

Cytotoxic T lymphocytes of heterozygous adult mice primed in vivo with minor alloantigens on cells of one parental H-2 genotype can be boosted in vitro to respond to minor alloantigens on cells of both the immunizing parental H-2 genotype (direct priming) and of the H-2 genotype of the other parent (cross-priming). We studied the ontogeny of this phenomenon and show that during early postnatal life the development of direct priming precedes that of cross-priming. The delayed maturation of cross-primed responses parallels the known development time sequence of functional antigen-presenting cells and provides evidence for the explanation of cross-priming in terms of antigen processing.

Collapsed vertebrae: a review of 659 autopsies.

One hundred and thirty-three cases showing collapse of one or more vertebral bodies were found in a review of 659 autopsy specimens of the thoracolumbar spine. There are 4 types of vertebral body collapse; 2 of the 4 have clinical significance.

Primary T-cell responses to minor alloantigens. II. Analysis of accessory cell requirements for the development of cytotoxic T lymphocytes.

The accessory cell requirements of cytotoxic T-lymphocyte (CTL) responses directed at multiple minor alloantigens are examined using a short-term, combined in-vivo and in-vitro protocol. The development of cytotoxic activity in vitro from T cells sensitized in vivo requires low-density accessory cells derived from the immunizing strain which have to be H-2 compatible with the responder population. The accessory activity of these cells can be by-passed by interleukin-2 (IL-2)-containing supernatant. Since IL-2 is a product of helper T (Th) cells secreted upon activation by antigen recognized in context of self H-2 and is known to stimulate antigen-activated cytotoxic T-lymphocyte precursors (CTL-P) non-specifically to effector CTL function, the results indicate that accessory cells interact in an H-2 restricted fashion with helper rather than cytotoxic T-lymphocyte precursors. The low-density accessory cells active in this system do not express Fc receptors (FcR) and are present in both the adherent and non-adherent fractions of spleen or lymph nodes.

Measurement of grip strength in the diagnosis of wrist pain.

Grip strength was assessed in patients with chronic wrist pain and correlated with the results of subsequent bone scans and pathology. The results showed a highly significant decrease of grip strength in patients with positive bone scans or confirmed wrist pathology compared with those with negative bone scans (p less than 0.01). We conclude that the detection of weakness of grip is a simple indicator of true pathology in "obscure" wrist pain.