Embryonic and foetal expression patterns of the ciliopathy gene CEP164.

Nephronophthisis-related ciliopathies (NPHP-RC) are a group of inherited genetic disorders that share a defect in the formation, maintenance or functioning of the primary cilium complex, causing progressive cystic kidney disease and other clinical manifestations. Mutations in centrosomal protein 164 kDa (CEP164), also known as NPHP15, have been identified as a cause of NPHP-RC. Here we have utilised the MRC-Wellcome Trust Human Developmental Biology Resource (HDBR) to perform immunohistochemistry studies on human embryonic and foetal tissues to determine the expression patterns of CEP164 during development. Notably expression is widespread, yet defined, in multiple organs including the kidney, retina and cerebellum. Murine studies demonstrated an almost identical Cep164 expression pattern. Taken together, these data support a conserved role for CEP164 throughout the development of numerous organs, which, we suggest, accounts for the multi-system disease phenotype of CEP164-mediated NPHP-RC.

Gonadal effects of a mouse Denys-Drash syndrome mutation.

Gonadal effects of the Denys-Drash syndrome (DDS) mutation Wt1(tmT396 )were examined in chimaeric and heterozygous mice. Since the only heterozygote was 41,XXY, Sertoli cell function was assessed by comparison with age-matched control XXY testes. Control XXY Sertoli cells showed immuno-expression of WT1 and androgen receptor (AR) indistinguishable from wild-type (40,XY), but expressed anti-Mullerian hormone (AMH). In contrast, DDS Sertoli cells showed only faint immuno-expression of WT1 and did not express AR or AMH. While XY<-->XY DDS chimaeras were male, XX<-->XY chimaeras were predominantly female. In the rare XX<-->XY DDS males the Sertoli cell lineage was largely derived from Wt1 mutant XY cells. We conclude that DDS mutant cells can form Sertoli cells, that the dominant mutation does not cause male sex reversal in mice but distorts the sex ratio of XX<-->XY chimaeras, and that there may be a link between WT1, AMH and AR expression by Sertoli cells in vivo.

Risk factors for hip fracture in men. Hip Fracture Study Group.

To identify risk factors for hip fracture in men, the authors conducted a case-control study involving 20 hospitals in Philadelphia, Pennsylvania, and 14 hospitals in Kaiser Permanente Medical Care Program of northern California. The 356 enrolled men had been admitted with a radiologically confirmed first hip fracture. The 402 control men either were from the Philadelphia area or were members of Kaiser Permanente and were frequency matched to the cases by age and ZIP code or telephone exchange. Information on potential risk factors was obtained through personal interviews. Men in the lowest quintile of body mass had a greatly increased risk of hip fracture compared with men in the heaviest quintile (odds ratio (OR) 3.8, 95% confidence interval (CI) 2.3-6.4). Premorbid lower limb dysfunction was associated with increased risks for hip fracture (OR 3.4, 95% CI 2.1-5.4). Increased risks were also observed with the use of cimetidine (OR 2.5, 95% CI 1.4-4.6) and psychotropic drugs (OR 2.2, 95% CI 1.4-3.3). Smoking cigarettes or a pipe increased the risk of hip fracture, and this association was independent of body mass. Finally, previous physical activity was markedly protective. Factors thought to affect bone density as well as factors identified as risk factors for falls appear to be important determinants of the risk of hip fracture in men. Physical activity may be a particularly promising preventive measure for men. Additional studies of the use of cimetidine on osteoporosis and osteoporotic fractures are indicated.

Altered cytokine expression in T lymphocytes from human immunodeficiency virus Tat transgenic mice.

Examination of the interaction between human immunodeficiency virus (HIV) regulatory gene products and the host immune system is fundamental to understanding the pathogenesis of HIV and could reveal possible targets for therapeutic intervention in the treatment of AIDS. The HIV Tat gene is a potential candidate for this type of strategy. Transgenic mice can be used to investigate the in vivo effects of Tat on the developing and dynamic immune system and on cellular gene expression. Thus, we have generated transgenic mice that harbor the HIV type 1 Tat gene under the transcriptional control of the human CD2 gene regulatory elements. This expression cassette results in high-level, tissue-specific transcription of the transgene within the T-cell compartment. In this report, we demonstrate the effects of Tat on the in vivo immune system. CD2-Tat transgenic mice show no signs of aberrant thymic development and have normal levels of T-cell subsets in the thymus and peripheral lymphoid organs. However, activated T cells from transgenic mice contain increased levels of tumor necrosis factor beta mRNA as well as biologically active tumor necrosis factor protein and express elevated levels of transforming growth factor beta and interleukin-4 receptor mRNA. These increased cytokine levels do not appear to alter mitogen- or antigen-stimulated responses or induce the formation of dermal lesions in ageing mice. Such investigations should provide insight into the combination of host immune factors mediating pathogenesis in HIV infection.

Specific ablation of human immunodeficiency virus Tat-expressing cells by conditionally toxic retroviruses.

The identification of human immunodeficiency virus (HIV) as the etiologic agent of AIDS has led to the proposal of novel intervention strategies to block HIV infection and viral replication or eliminate HIV-infected cells. We have produced recombinant retroviruses for a molecular ablation system, whereby a toxin gene can be delivered to hematopoietic cells for the specific elimination of HIV Tat-expressing cells. For this cell-specific ablation, we have coupled the conditional toxin herpes simplex virus type 1 thymidine kinase (tk) gene to the HIV-2 promoter and Tat responsive region (TAR) in order that transcriptional activity be under the absolute control of HIV and simian immunodeficiency virus Tat trans-activator proteins. Since the HIV-2 promoter has a considerable level of basal expression in the absence of Tat, we constructed a number of modifications in the HIV-2 promoter to minimize the risk of cytotoxicity to cells not containing HIV Tat. We demonstrate that certain promoter modifications reduce basal transcription while maintaining high trans-activated levels of expression when transfected or transduced by retroviral vectors into several different cell lines. In mouse and human cells infected with HIV-2 tk retroviruses, we show that Tat-induced expression from the HIV-2 promoter results in differential ablation and a massive reduction in Tat-positive cells after ganciclovir treatment. Thus, the retroviruses produced in these studies may be applicable to HIV ablative therapy.

Studies of HIV-2 promoter activity and cell specific ablation.

We have a developed a retroviral mediated molecular ablation method to specifically eliminate HIV Tat-expressing cells. This approach utilizes the Tat-inducible HIV-2 promoter and a conditional toxin gene. The Herpes Simplex Virus thymidine kinase gene product is toxic to mammalian cells only after treatment with Ganciclovir (GCV) or other nucleoside analogues. We demonstrate here that certain promoter modifications can decrease basal expression while retaining the ability to be transactivated. Furthermore, we show that a HIV-2 promoter thymidine kinase gene cassette transduced via retroviral vectors into tissue culture cells can specifically promote the ablation of HIV-Tat expressing cells in the presence GCV. We also show that there is a large differential in HIV-thymidine kinase gene transcription and lethal drug dose between Tat-expressing cells and Tat-negative cells.

Marihuana and work performance: results from an experiment.

Determining the relationship between marihuana and economic activity is an important factor in establishing social policy in this area. The effects of marihuana availability and consumption on production, hours worked, and output per hour are reported from an experimental microeconomy involving resident volunteer human subjects. The statistical analysis shows no effect of marihuana on total output or total hours worked for experimental as compared to control conditions, although marihuana use was generally associated with a simultaneous decision to engage in passive leisure activities in the period immediately following smoking. These results suggest a hypothesis about the general relationship between marihuana and economic activity that is used to integrate the results of several other studies with those reported here.