Factors that influence viability and function of cryopreserved peripheral blood mononuclear cells (PBMC)were identified on 54 samples from 27 AIDS Clinical Trial Units. PBMC viability ranged from 1 to 96% with a median of 70%, was higher in laboratories with experienced staff, and was not significantly associated with CD4 cell number. Function of cryopreserved PBMC, measured by lymphocyte proliferation, was associated with viability. Preparations with viability greater than or equal to 70% had consistent proliferative responses and were suitable for functional analyses.Highly active antiretroviral therapy often results in potent and durable suppression of human immunodeficiency virus (HIV) replication, elevation of CD4 cell counts, decreased incidence of opportunistic infections, and increased survival in HIV-infected patients, including those with advanced disease (6, 7). Immunologic studies in these patients (1, 4) show improvement of some immune functions, but not others, raising the question of whether restoration of this immune function will be complete. Such studies are sometimes performed on cryopreserved peripheral blood mononuclear cells (PBMC). Our understanding of the extent, timing, and determinants of the immune reconstitution will be expanded if assays can be reliably performed on frozen and thawed cells from well-characterized patients.To identify biological and/or technical factors that influence functional assays performed on cryopreserved PBMC, we analyzed the results of the cryopreservation quality control (QC) program established for the immunology component of protocol AIDS Clinical Trial Group (ACTG) 360, "A Longitudinal Study of the Predictive Value of Quantitative CMV Viremia Assays for CMV Disease in Persons with AIDS". This is an ongoing study which enrolled 403 patients at 27 AIDS Clinical Trials Units (ACTU). PBMC from all subjects were cryopreserved every 4 months at ACTU sites. Personnel at the ACTU were asked to freeze the cells following the ACTG cryopreservation protocol, which included separation of PBMC on FicollHypaque gradients, washing the cells, and resuspending them at 10 7 PBMC/ml in cold fetal calf serum with 10% dimethyl sulfoxide. Working on ice, we aliquoted the cell suspension into cryovials at 0.5 ml/vial (5 ϫ 10 6 cells/vial), gradually brought the suspension to a temperature less than or equal to Ϫ70°C over 24 h by using Mr. Frosty devices (Curtis Matheson Scientific) or controlled-rate freezers, and then transferred the frozen aliquots to liquid nitrogen tanks. For testing, the cryovials were shipped every 6 months on dry ice to the University of Colorado Health Sciences Center. The QC protocol was performed on randomly selected samples from each participating ACTU. Cells were thawed by quickly bringing them to 4°C followed by slow addition of cold RPMI medium containing 10% human AB serum. Cells were washed and counted in 0.5% trypan blue to assess numbers of viable cells. The total number of cells in each vial and the percentage and absolute number of viable ce...

Cytomegalovirus-specific IFN-gamma has a unique value as an immunological predictor of cytomegalovirus reactivation, demonstrating the importance of cellular immune responses in the control of cytomegalovirus replication in HAART recipients.

The authors review the structural, pharmacologic, and clinical aspects of bisphosphonates, a class of drugs currently used to treat several disorders of bone and calcium metabolism. Pertinent literature on the bisphosphonates was reviewed with the help of a MEDLINE search and several bibliographies, including published clinical trials, monographs, and review articles. The bisphosphonates are analogs of pyrophosphate that, when given orally or intravenously, bind avidly to exposed bone mineral and disrupt bone turnover. These agents comprise three groups or generations, based on their potency and chemical structures. All three generations are effective in treating hypercalcemia, Paget's disease of bone, osteoporosis, and other disorders of accelerated bone turnover. The third-generation agents have the greatest potency and offer the promise of a convenient way to suppress or prevent osseous metastasis in patients with certain malignancies. As a group, these agents are well tolerated and, when administered correctly, rarely cause toxicity. The bisphosphonates are safe and effective agents for the treatment of disorders of accelerated bone turnover.

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As we celebrate the 50th anniversary of the physician assistant (PA) profession and specifically PA education, think of the tens of thousands of clinical preceptors who were or currently still are involved in the education of PA students. The clinical phase of PA programs has become the rate-limiting issue in PA education. For decades, developing clinical education sites was relatively easy. Over the last decade, rapid expansion in medical, nurse practitioner, and PA education programs has resulted in greater challenges in obtaining necessary clinical training sites. This article attempts to address several of the current challenges in PA clinical education.