Huntingtin-encoded polyglutamine expansions form amyloid-like protein aggregates in vitro and in vivo

The mechanism by which an elongated polyglutamine sequence causes neurodegeneration in Huntington's disease (HD) is unknown. In this study, we show that the proteolytic cleavage of a GST-huntingtin fusion protein leads to the formation of insoluble high molecular weight protein aggregates only when the polyglutamine expansion is in the pathogenic range. Electron micrographs of these aggregates revealed a fibrillar or ribbon-like morphology, reminiscent of scrapie prions and beta-amyloid fibrils in Alzheimer's disease. Subcellular fractionation and ultrastructural techniques showed the in vivo presence of these structures in the brains of mice transgenic for the HD mutation. Our in vitro model will aid in an eventual understanding of the molecular pathology of HD and the development of preventative strategies.     

A multicenter study of platelet recovery and utilization in patients after myeloablative therapy and hematopoietic stem cell transplantation

An observational study was conducted at 18 transplant centers in the United States and Canada to characterize the platelet recovery of patients receiving myeloablative therapy and stem cell transplantation and to determine the clinical variables influencing recovery, determine platelet utilization and cost, and incidence of hemorrhagic events. The study included 789 evaluable patients transplanted in 1995. Clinical, laboratory, and outcome data were obtained from the medical records. Variables associated with accelerated recovery in multivariate models included (1) higher CD34 count; (2) higher platelet count at the start of myeloablative therapy; (3) graft from an HLA-identical sibling donor; and (4) prior stem cell transplant. Variables associated with delayed recovery were (1) prior radiation therapy; (2) posttransplant fever; (3) hepatic veno-occlusive disease; and (4) use of posttransplant growth factors. Disease type also influenced recovery. Recipients of peripheral blood stem cells (PBSC) had faster recovery and fewer platelet transfusion days than recipients of bone marrow (BM). The estimated average 60-day platelet transfusion cost per patient was $4,000 for autologous PBSC and $11,000 for allogeneic BM transplants. It was found that 11% of all patients had a significant hemorrhagic event during the first 60 days posttransplant, contributing to death in 2% of patients. In conclusion, clinical variables influencing platelet recovery should be considered in the design and interpretation of clinical strategies to accelerate recovery. Enhancing platelet recovery is not likely to have a significant impact on 60-day mortality but could significantly decrease health care costs and potentially improve patient quality of life.     

A comparison of resource costs for head and neck reconstruction with free and pectoralis major flaps

A series of 178 immediate reconstructions with regional or distant tissue for repair of oropharyngeal defects caused by treatment of head and neck cancer was reviewed to determine whether reconstruction with free flaps was more or less expensive than reconstruction with regional myocutaneous flaps. In this series, three types of flaps were used: the radial forearm free flap (n = 89), the rectus abdominis free flap (n = 56), and the pectoralis major myocutaneous flap (n = 33). Resource costs were determined by adding all costs to the institution of providing each service studied using salaried employees (including physicians). The two free-flap groups were combined to compare free flaps with the pectoralis major myocutaneous flap, a regional myocutaneous flap. Failure rates in the two groups were similar (3.0 percent for pectoralis major myocutaneous flap, 3.4 percent for free flaps). The mean costs of surgery were slightly higher for the free flaps, but the subsequent hospital stay costs were lower. Therefore, the total mean resource cost for the free-flap group ($28,460) was lower than the cost for the myocutaneous flap group ($40,992). The pectoralis major myocutaneous flap may have been selected for more patients with advanced disease and systemic medical problems, contributing to longer hospitalization and added cost. Nevertheless, this study suggests that free flaps are not more expensive than other methods and may provide cost savings for selected patients.     

Cell cycle gene regulation in reversibly differentiated new human hepatoma cell lines

We performed a comparative investigation of the immunomorphological characteristics of lymphatic and blood microvascular endothelial cells in normal human skin, cutaneous lymphangiomas, and hemangiomas, employing a pre-embedding immunogold electron microscopic technique. We stained for cell membrane proteins that are commonly used for light microscopic characterization of blood endothelial cells. With blood microvascular endothelial cells, we observed uniform labeling of the luminal cell membranes with monoclonal antibodies (MAbs) JC70 (CD31), EN-4 (CD31), BMA120, PAL-E, and QBEND-10 (CD34), and strong staining of the vascular basal lamina for Type IV collagen under normal and pathological conditions. In contrast, lymphatic microvascular endothelial cells in normal human skin and in lymphangiomas displayed, in addition to a luminal labeling, pronounced expression of CD31 and CD34 along the abluminal cell membranes. Moreover, CD31 was preferentially detected within intercellular junctions. The expression of CD34 was mostly confined to abluminal endothelial microprocesses and was upregulated in lymphangiomas and hemangiomas. Type IV collagen partially formed the luminal lining of initial lymphatics and occasionally formed bridges over interendothelial gaps. Our findings suggest a function of transmigration protein CD31 in recruitment of dendritic cells into the lymphatic vasculature. CD34 labeling may indicate early endothelial cell sprouting. The distribution of Type IV collagen also supports its role as a signal for migration and tube formation for lymphatic endothelial cells.     

Comparison of thymidine and folinic acid protection from methotrexate toxicity in human lymphoid cell lines

Hypoxanthine, thymidine, and folinic acid protection from methotrexate cytotoxicity were compared in human lymphoid cell lines variably sensitive to thymidine-induced growth suppression. Hypoxanthine protection differed among the cell lines, and the dose-response relationship for protection occurred within the physiologic bone marrow hypoxanthine concentration range. The slopes of the thymidine protection curves were virtually superimposable in a B cell line versus a T cell line, but threefold to fourfold higher thymidine concentrations were required to maximally protect the B versus the T cell line. Thymidine (plus hypoxanthine) protection was superior to that of folinic acid in both the B and the T cell lines when protection was delayed. As the interval between methotrexate and folinic acid exposure was progressively delayed, there was a linear decline in the degree of maximum protection in both cell lines. However, as thymidine exposure was progressively delayed, maximal protection was maintained, except at 12 hours in the B cell line. The influence of methotrexate on thymidine-induced growth suppression was studied. Methotrexate enhanced thymidine-induced growth suppression in sensitive cells as manifested by a significant shift of the dose-response curve. Deoxycytidine protection from thymidine toxicity was superior in the presence of methotrexate. The results of these studies indicate that thymidine protection and folinic acid protection against methotrexate toxicity produce different effects, which in part are dependent on the cell type. The complexity of these interactions points out the need for further studies.     

Use of discriminant analysis to study the personality traits of patients with the cerebral form of hypertension

Results of experimental psychological examinations of 81 patients with the cerebral form of hypertensive disease are presented. The examinations were carried out using the method of personal subjective scaling. The informative value of 41 personal characteristics suitable for differentiation of the patients with reference to the disease gravity and the age at which they developed the disease was determined. On the basis of 10 personal characteristics found to be the most informative, linear discriminant functions were constructed which provided the following accuracy of the differentiation with reference to the disease gravity: correct answers -- 61%, vague -- 25%, erroneous -- 14%; with reference to the age of the disease development: correct answers -- 78%, vague -- 8%, erroneous -- 14%.