Large-scale production of Ba(2+)-alginate-coated islets of Langerhans for immunoisolation

Islet xenografts immunisolated in alginate capsules have been proposed by many groups for clinical islet transplantation. However, diffusion limitations and the total volume of microcapsules required for transplantation are, among other things, factors which have so far prevented successful clinical application. In this study, these problems have been overcome by immobilisation of rat and porcine islets in a Ba(2+)-cross-linked alignate matrix using an air jet droplet generator technique in combination with subsequent density-gradient purification. This procedure leads to high yields of islets coated with a tailored, thin layer of cross-linked alginate which protects the islets against cytotoxic compounds present in human plasma. The recovery of encapsulated rat and porcine islets was about 70%. Empty capsules were nearly completely removed. Using this technique, the total volume of the resulting microcapsules increased only by a factor of about 1.5 compared to the volume of free islets. The technique can be used for large-scale production of coated islets.     

Multidisciplinary evaluation of preschool children in a military psychiatry clinic: a 10-year comparison and a brief outcome study

A little over a decade ago, the Child and Adolescent Psychiatry Service at Tripler Army Medical Center opened the Child Study Group (CSG), a multidisciplinary diagnostic team clinic for preschool children. The methods and results of the clinic were reported previously (Lee, 1987). The current study is a comparison of the cohort of children seen from January through December 1984 with the parallel group seen from January through June 1994. The paper also presents a brief follow-up study of the children seen in 1994.     

Fine structure of the retinal pigment epithelium of Oreochromis niloticus L. (Cichlidae; Teleostei) in light- and-dark adaptation

To examine pathological changes of melanocytes in photodamaged skin, we performed a comparative cytomorphometric analysis and a qualitative observation of melanocytes from sun-exposed and sun-protected facial skin at the electron microscopic level. The characteristic ultrastructural features of melanocytes in photodamaged skin included a statistically significant increase in their number, a marked nuclear heterogeneity, signs of cell activation, close apposition to photodamaged degenerate keratinocytes, degenerative changes represented by large intracytoplasmic vacuoles, and frequent direct contacts with Langerhans cells. Cytomorphometric analysis revealed significant decreases in cell and nuclear sizes, increases in cell and nuclear perimeters accompanied by irregular contours, and higher degrees of nuclear ellipticity in sun-exposed melanocytes. This study demonstrates that there are remarkable differences in the morphology of melanocytes between photoaged and intrinsically aged facial skin, and supports the concept that photoageing processes contribute to cytological alterations in melanocytes.     

Energy prices and investment over the business cycle

This paper develops a theoretical investment equation for the firm which explicitly includes the relationship between investment and the price of energy. Using intertemporal comparative statics, we investigate how economic conditions affect that relationship. In a two-period model, the net present value of the firm's cash inflows is maximized subject to constraints. The resulting investment equation for the firm is summed over all firms to produce an aggregate investment equation. By assuming that aggregate shocks do not affect every firm simultaneously, we could investigate the effects of varying economic conditions on the relationship under study. We find that energy price increases will retard aggregate real investment. Also, this restraining impact will be greatest during boom periods and least during recessions. Further, the impact of an energy price increase on aggregate investment diminishes as the level of energy prices increases. We show that simple OLS techniques are not appropriate for empirical estimation of the relationship between aggregate investment and energy price; they could produce inconsistent results depending on the time period studied because of the business cycle effects. A survey of corporations along product lines would be useful to test for such non-linearity.     

Vpr of simian immunodeficiency virus of African green monkeys is required for replication in macaque macrophages and lymphocytes

The genomes of simian immunodeficiency viruses isolated from African green monkeys (SIVagm) contain a single accessory gene homolog of human immunodeficiency virus type 1 (HIV-1) vpr. This genomic organization differs from that of SIVsm-SIVmac-HIV-2 group viruses, which contain two gene homologs, designated vpr and vpx, which in combination appear to share the functions of HIV-1 vpr. The in vitro role of the SIVagm homolog was evaluated with molecularly cloned, pathogenic SIVagm9063-2. These studies revealed that this gene shares properties of HIV-1 vpr, such as nuclear and virion localization. In addition, SIVagm mutants with inactivating mutations of vpr are unable to replicate in nondividing cells, such as macaque monocyte-derived macrophages, but replicate to almost wild-type levels in a susceptible human T-cell line. The transport of virus preintegration complexes into the nucleus in primary macrophages, as measured by the production of unintegrated circular viral DNA, is less efficient for the mutant viruses than it is for the wild-type virus. SIVagm mutants also replicate inefficiently in primary macaque peripheral blood mononuclear cells, with a propensity for substitutions that remove the inserted inactivating stop codon. These data, in conjunction with recent findings that the Vpr protein is capable of inducing G2 arrest, are consistent with designation of this SIVagm accessory gene as vpr to reflect its shared functions and properties with HIV-1 vpr.