Proton imaging for medical applications

In order to demonstrate the potential advantages of proton imaging for medical use, a 205-MeV proton beam was developed using the Argonne National Laboratory Booster I synchrotron. Data were taken using a narrow scanning beam and an electronic detector system. The dose reduction and an improved mass resulution over the radiographs. The images also show significant differences in the proton stopping power of different tissues, thus demonstrating considerable potential in soft-tissue imaging. The development of a proton tomographic scan system is also briefly discussed.     

Volume-dependent human blood polymorphonuclear leukocyte heterogeneity demonstrated with counterflow centrifugal elutriation

Human peripheral blood polymorphonuclear leukocytes (PMNs) have recently been recognized as a heterogeneous population of cells. Consideration has not been given to the possibility that size may be an additional physical characteristic demonstrating heterogeneity. Using counterflow centrifugal elutriation, we have demonstrated that PMNs can be isolated into at least six volume-dependent fractions. A positive correlation exists for PMN size and superoxide anion release upon stimulation with f-Met-Leu-Phe or phorbol myristate acetate. Total granule contents were also noted to be greater in larger PMN fractions, with a constant percent of release upon stimulation. The implications of these findings are discussed.     

Adhesion of perichondrial cells to a polylactic acid scaffold.

The number of chondrogenic cells available locally is an important factor in the repair process for cartilage defects. Previous studies demonstrated that the number of transplanted rabbit perichondrial cells (PC) remaining in a cartilage defect in vivo, after being carried into the site in a polylactic acid (PLA) scaffold, declined markedly within two days. This study examined the ability of in vitro culture of PC/PLA constructs to enhance subsequent biomechanical stability of the cells and the matrix content in an in vitro screening assay. PC/PLA constructs were analyzed after 1 h, 1 and 2 weeks of culture. The biomechanical adherence of PC to the PLA scaffold was tested by subjecting the PC/PLA constructs to a range of flow velocities (0.25-25 mm/s), spanning the range estimated to occur under conditions of construct insertion in vivo. The adhesion of PC to the PLA carrier was increased significantly by 1 and 2 weeks of incubation, with 25 mm/s flow causing a 57% detachment of cells after 1 h of seeding, but only 7% and 16% after 1 and 2 weeks of culture, respectively (p<0.001). This adherence was associated with marked deposition of glycosaminoglycan and collagen. These findings suggest that pre-incubation of PC-laden PLA scaffolds markedly enhances the stability of the indwelling cells.     

Biomechanical regulation of type I collagen gene expression in ACLs in organ culture.

In this study, an ex vivo organ culture system that allows the application of controlled loads to the anterior cruciate ligament (ACL) was designed and used to characterize the influence of a step input in mechanical load on gene expression. A procedure for isolating bone-ACL-bone (B-ACL-B) complexes from rat knees was developed. After harvest and 24 hour culture, B-ACL-B complexes exhibited percentages of viability similar to that in intact ACLs (approximately 90%). Application of a physiologically relevant load of 5 N (superimposed on a I N tare load) resulted in changes in levels of mRNA encoding type I collagen. While levels of type I collagen mRNA significantly increased 32+/-13% (mean +/- standard errors of the mean (SEM)) over controls within the first hour of loading, levels decreased significantly to 44+/-9% of control after 2 h. Displacements induced by the 5 N load were measured by video dimensional analysis. Calculated axial strains of 0.141+/-0.034 were achieved rapidly during the first hour and remained essentially unchanged thereafter. These results demonstrate the feasibility of maintaining ligaments in organ culture and illustrate the time course expression of type I collagen following the application of a mechanical load.     

Liquid preservation of human neutrophils stored in synthetic media at 22 degrees C: controlled observations on storage variables

The purpose of this study was to use a chemically defined medium to identify essential substances and optimal conditions for the liquid storage of neutrophils at 22 degrees C. Several commercially available synthetic media were evaluated: L-15, McCoy's 5a, M199, minimum essential medium, Dulbecco's MEM, NCTC135, and RPMI 1640. Proteins, glucose, pH, and neutrophil concentration were systematically studied. Neutrophils were harvested by centrifugal cell separators or phlebotomy, and their maintenance was evaluated by monitoring cell counts, dye exclusion, phagocytosis, bacterial killing, and chemotaxis. Neutrophils stored equally well in all synthetic media except L-15; however, chemotaxis was poorly maintained in synthetic media as compared with autologous plasma. RPMI 1640 was arbitrarily selected as a basal medium to evaluate storage variables. RPMI 1640 supplemented with albumin to a concentration of 1% improved chemotaxis and was equivalent to plasma as a storage medium with regard to the in vitro functions tested. Cohn fractions IV-1, IV-4, and gamma globulin were not effective substitutes for albumin. Glucose is essential for neutrophil storage; its absence from the medium correlated with poor cell function. Optimal glucose requirements depend on the cell concentration. High glucose concentrations were toxic to neutrophils; at 1,000 mg/dL, chemotaxis was depressed by 58%. Glucose utilization was dependent on the initial pH of the medium and on the cell concentration. A wide range of hydrogen ion concentrations was tolerated, and the optimum pH range was 7.2 to 7.8. Cell concentration is an important variable because it affects the pH of the medium as well as glucose utilization.     

Artificial urinary sphincters in children: radiographic evaluation

Use of the artificial urinary sphincter to treat incontinence in children has increased over the past decade. The hydraulic fluid used in this device is radiopaque, and the radiologist is directly involved in its evaluation. Despite advances in design and surgical technique, mechanical failures and other complications occur. Our experience with 34 artificial sphincters implanted in 31 children during 1973-1983 is reviewed, giving a method of radiographic evaluation, diagnostic errors to avoid, examples of sphincter malfunction, and common complications.     

Factor XIII A is synthesized and expressed on the surface of U937 cells and alveolar macrophages

Factor XIII A subunit was detected in U937 cells and human alveolar macrophages by immunohistology and Western blotting. U937 cells synthesize factor XIII A subunit de novo under serum-free, platelet- free conditions, as indicated by 35S-methionine labeling and immunoprecipitation. Thrombin-dependent activity was demonstrated to account for 98% of the total transglutaminase activity in U937 cells (1.5 micrograms per 0.5 X 10(6) cells/mL). Intact U937 cells and alveolar macrophages and homogenates from these cells cross-linked fibrin to form gamma-gamma and alpha-polymers. Factor XIII A was detected on the surface of intact U937 cells and macrophages by flow cytometry and 125I-labeling and immunoprecipitation. Cell surface expression of factor XIII A was augmented in the presence of several soluble macrophage activators; however, no concurrent increase in its biosynthesis was observed. The presence and cell surface expression of factor XIII A subunit within macrophages suggest new pathways by which these cells may function in clotting and in the remodeling of the extracellular matrix during inflammation and wound healing.     

Bone marrow transplantation for the treatment of acute nonlymphoblastic leukemia in children aged less than 2 years

Eleven children with acute nonlymphoblastic leukemia in first remission who were less than 2 years of age at diagnosis were treated with 120 mg/kg of cyclophosphamide, 12-Gy fractionated total-body irradiation, and marrow transplantation. Seven patients remain in complete remission from 3.5 to 13.8 years posttransplant, four for more than 6.75 years. The immediate posttransplant course was relatively uncomplicated in surviving patients. No child developed severe graft-v-host disease. The major long-term side effect has been a slowing in growth. Although the prognosis for such children with conventional chemotherapy remains poor, intensive cytotoxic therapy and marrow transplantation offers an alternative therapy with a chance for cure.