End labeling studies of fragmented DNA in the avian growth plate: evidence of apoptosis in terminally differentiated chondrocytes

The chondro-osseous junction has been the subject of considerable scrutiny, especially in terms of the fate and role of the terminally differentiated chondrocyte. Although it has been proposed that these cells change their phenotype and survive in the epiphysis, possibly as osteoblasts, evidence from a number of other studies suggests that chondrocytes may undergo apoptosis or programmed cell death. A useful test for programmed cell death is to end label DNA in cryosections using the commercial reagent ApopTag and detect antibody binding to fragmented DNA by epifluorescence; more direct assessments include examination of the nucleus for condensation of chromatin evaluating fragmentation through alkaline and pulsed field agarose gel electrophoresis of DNA, and measuring apoptosis by flow cytometry. We found that we could label cells in the proliferative and the hypertrophic region of the proximal tibial growth plate of the chick with ApopTag. Most of the chondrocytes in the hypertrophic region were labeled by the reagent; in contrast, few proliferative chondrocytes were stained by the end-labeling procedure. Both agarose and pulsed field electrophoresis were used to confirm that there was fragmentation of chondrocyte DNA. Alkaline gel electrophoresis indicated that there was more fragmentation of DNA from hypertrophic cells than from proliferative chondrocytes. Further evidence in support of apoptosis was provided by electron microscopic observation of cells in the hypertrophic region of the growth plate. We noted that many of the cells in this region of the growth plate appeared to be undergoing programmed cell death since their nuclei contained condensed chromatin. Finally, we used flow cytometry to analyze chondrocytes isolated from the proliferating and hypertrophic regions of the growth plate for apoptosis. Dual parameteric flow cytometric contour plots of Hoechst and 7-amino-actinomycin D fluorescence showed that abut 8% of cells in the plate were apoptotic. Most of these cells were in hypertrophic cartilage. In summary, the results of this investigation indicate that chondrocytes terminate their life history by apoptosis. While it is possible that the terminal labeling studies may overestimate the number of cells undergoing this event, the data lend credence to the view that cells are removed from the epiphysis through apoptosis. If this is the case, then chondrocytes probably enter the terminal phase of their life as fully functioning cells and genomic, and/or local environmental conditions provide termination signals that initiate events that lead to programmed cell death.     

Arthroscopic-assisted reduction of distal radius fractures

The outcomes of seven patients with severe comminuted intraarticular fractures of the distal radius treated by arthroscopic reduction and percutaneous external fixation (ARPEF) were retrospectively reviewed. All of the fractures were classified as C3 types using the AO classification scheme. Outcomes were evaluated using the Gartland and Werley functional criteria, an objective wrist examination, a radiographic analysis, and a self-assessment outcome form at an average follow-up of 27 months (range, 12 to 45 months). All patients were free of pain and had returned to their prior occupations. No patient had articular incongruency of greater than 1 mm, and there was no evidence of radiocarpal degenerative change. Active range of motion and maximal grip strength averaged 92% and 98%, respectively, of the uninjured wrist. The technique of arthroscope-assisted reduction and percutaneous external fixation yielded excellent results in a small group of patients, with minimal complications.     

Radiohumeral arthrodesis for salvage of failed total elbow arthroplasty

Ulnohumeral arthrodesis is the standard technique for elbow fusion. The geometry and surface area of the distal humerus and proximal ulna enhance the chances of fusion while maintaining some wrist motion. A case of a patient with multiple failed elbow procedures in which the standard ulnohumeral fusion was not possible is presented. A radiohumeral arthrodesis was performed in an attempt to obtain a stable, nonpainful elbow. After complete healing of the fusion, the patient was able to use the arm for most functions. This technique is presented as an option for salvage failed elbow arthroplasty in the face of significant bone loss.     

One world, one hope: the cost of providing antiretroviral therapy to all nations

OBJECTIVE: To estimate the potential direct cost of making triple combination antiretroviral therapy widely available to HIV-positive adults and children living in countries throughout the world. METHODS: For each country, antiretroviral costs were obtained by multiplying the annual cost of triple antiretroviral therapy by the estimated number of HIV-positive persons accessing therapy. Per capita antiretroviral costs were computed by dividing the antiretroviral costs by the country's total population. The potential economic burden was calculated by dividing per capita antiretroviral costs by the gross national product (GNP) per capita. All values are expressed in 1997 US dollars. RESULTS: The potential cost of making triple combination antiretroviral therapy available to HIV-positive individuals throughout the world was estimated to be over US$ 65.8 billion. By far the greatest financial burden was on sub-Saharan Africa. The highest per capita drug cost in this region would be incurred in the subregions of Southern Africa (US$ 149) followed by East Africa (US$ 116), Middle Africa (US$ 44), and West Africa (US$ 42). In the Americas, subregional data indicated the highest per capita drug cost would be in the Latin Caribbean (US$ 22), followed by the Caribbean (US$ 17), Andean Area (US$ 7), the Southern Cone (US$ 6), North America (US$ 6), and Central American Isthmus (US$ 5). In Asia and Europe the percentage of the GNP necessary to finance drug therapy was less than 1% in most countries examined. CONCLUSION: Our results demonstrate that the cost of making combination antiretroviral therapy available worldwide would be exceedingly high, especially in countries with limited financial resources.     

Trace elements in formulas based on cow and soy milk and in Austrian cow milk determined by inductively coupled plasma mass spectrometry

With inductively coupled plasma-mass spectrometry (ICP-MS), the 18 trace elements Ba, (Be), (Bi), Cd, Co, Cs, Cu, La, Li, Mn, Mo, Pb, Rb, (Sb), (Sn), Sr, (Tl), and Zn were quantified in the digests of 13 formulas based on cow milk, of two formulas based on soy protein, of two milk powders, from which formulas were prepared, of two samples of Austrian cow milk, and in the water, with which the powders were suspended. Concentrations in parentheses were at or below the method detection limits in the formulas. The accuracy and precision of the analytical procedure tested with milk powder reference materials BCR 063 and BCR 150 were satisfactory. The concentrations of trace elements in the powders vary considerably from batch to batch. The ratios of high to low concentrations ranged from 1.1 to 4.8 and were higher for the essential trace elements Co, Cu, Mn, Mo, Sn, and Zn than for nonessential or toxic elements. The contribution of tap water from the water system of the city of Graz, Austria to the concentrations of trace elements in the formulas ranges from 45% for Pb to 0.2% for Rb and is negligible, for instance, for Cd, Cs, La, Mo, and Sn. Preformulas and follow-up formulas are partly supplemented with the essential trace elements Cu, Mn, and Zn and, therefore, concentrations of these trace elements in the formulas vary considerably. However, supplementation of a formula with a particular element must not necessarily result in higher concentrations compared to non-supplemented formulas. Concentrations of the essential elements were in the following ranges for preformulas, follow-up formulas, soy-based formulas (in microg/kg): Co, 8.3-11.2, 4.5-13, 5.0-5.7; Cu, 330-750, 27-730, 440-530; Mn, 33-580, 40-390, 440-530; Mo, 10-32, 9-39, 44-46; Sn, <0.44-3.8, <0.44-1.0, <0.44-5.8; Zn, 3340-11,380, 4120-7100, 5590-6,840. A preformula supplemented with Mn had a 10 times higher manganese concentration than preformulas without supplementation. Concentrations of all trace elements quantified were lower in cow milk than in formulas and do not meet the dietary requirements of infants.     

A novel cyclic adenosine monophosphate analog induces hypercalcemia via production of 1,25-dihydroxyvitamin D in patients with solid tumors

The treatment of cancer patients with conventional chemotherapy is sometimes associated with severe systemic toxicity and only a minimal survival benefit. Because of this, new less toxic and more efficacious treatments have been sought. 8-Chloro-cAMP (8-Cl-cAMP) is one of a new generation of anticancer drugs that act at the level of signal transduction. In preclinical models, 8-Cl-cAMP modulates protein kinase A (PKA) leading to growth inhibition and increased differentiation of cancer cells. 8-Cl-cAMP was given to 16 patients with advanced cancer as an infusion via an indwelling subclavian venous catheter. We showed that 8-Cl-cAMP had a parathyroid hormone-like effect leading to increased synthesis of renal 1,25-dihydroxyvitamin D [up to 14 times the baseline value, median 3.6 times; P = 0.00001 (Student's paired t test)]. This produced the dose-limiting toxicity of reversible hypercalcemia that could not be controlled by the administration of either pamidronate or dexamethasone. The treatment was otherwise well tolerated, and other cAMP-dependent pathways (cortisol and TSH) were not affected, emphasizing the marked differences between organs in their sensitivity to this cAMP analog. Our results have shown that 8-Cl-cAMP is biologically active, and it is feasible that if the hypercalcemia can be controlled, then this drug may have a role as a single agent, or as a short infusion between cycles of chemotherapy.     

Content-addressable data storage by use of volume holograms

Data stored as volume holograms-optical interference patterns imprinted into a photosensitive storage material-can be accessed both by address and by content. An optical correlation-based search compares each input query against all stored records simultaneously, a massively parallel but inherently noisy analog process. With data encoding and signal postprocessing we demonstrate a holographic content-addressable data-storage system that searches digital data with high search fidelity.