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Trithorax (TRX) and ASH1 belong to the trithorax group (trxG) of transcriptional activator proteins, which maintains homeotic gene expression during Drosophila development. TRX and ASH1 are localized on chromosomes and share several homologous domains with other chromatin-associated proteins, including a highly conserved SET domain and PHD fingers. Based on genetic interactions between trx and ash1 and our previous observation that association of the TRX protein with polytene chromosomes is ash1 dependent, we investigated the possibility of a physical linkage between the two proteins. We found that the endogenous TRX and ASH1 proteins coimmunoprecipitate from embryonic extracts and colocalize on salivary gland polytene chromosomes. Furthermore, we demonstrated that TRX and ASH1 bind in vivo to a relatively small (4 kb) bxd subregion of the homeotic gene Ultrabithorax (Ubx), which contains several trx response elements. Analysis of the effects of ash1 mutations on the activity of this regulatory region indicates that it also contains ash1 response element(s). This suggests that ASH1 and TRX act on Ubx in relatively close proximity to each other. Finally, TRX and ASH1 appear to interact directly through their conserved SET domains, based on binding assays in vitro and in yeast and on coimmunoprecipitation assays with embryo extracts. Collectively, these results suggest that TRX and ASH1 are components that interact either within trxG protein complexes or between complexes that act in close proximity on regulatory DNA to maintain Ubx transcription.

The determined state of Drosophila imaginal discs depends on stable patterns of homeotic gene expression. The stability of these patterns requires the function of the ash1 gene, a member of the trithorax group. The primary translation product of the 7.5-kb ash1 transcript is predicted to be a basic protein of 2144 amino acids. The ASH1 protein contains a SET domain and a PHD finger. Both of these motifs are found in the products of some trithorax group and Polycomb group genes. We have determined the nucleotide sequence alterations in 10 ash1 mutant alleles and have examined their mutant phenotype. The best candidate for a null allele is ash1. The truncated protein product of this mutant allele is predicted to contain only 47 amino acids. The ASH1 protein is localized on polytene chromosomes of larval salivary glands at > 100 sites. The chromosomal localization of ASH1 implies that it functions at the transcriptional level to maintain the expression pattern of homeotic selector genes.

PACs, AVGs, EDGs--the health care alphabet soup is burbling as HCFA considers a mandate for a Medicare outpatient PPS. And some third-party payers are devising their own outpatient PPSs for non-Medicare enrollees in the interest of curbing high ambulatory care costs. Here is a report on the status and timing of all these efforts from a variety of participants and observers.

A prospective evaluation of zinc status was made in 63 randomly selected patients with Crohn's disease. In the patients, mean serum and 24-hr urinary zinc values--105 microgram/dl and 383 microgram/day, respectively--were not different from controls. However, 46% of these patients had less than normal serum zinc and 36% had low urinary zinc excretions. Simultaneous reductions in both serum and urinary zinc were detected in 19% of patients. A direct correlation (P = 0.01) was found between serum levels of zinc and the concentration of albumin, the major zinc-binding protein, in outpatients but not in hospitalized patients or patients with Crohn's disease as a whole. Intake of zinc was surprisingly good--a mean intake of 13.4 +/- 1.4 mg/day. A significant (P = 0.006) association was found between urinary zinc and the Crohn's disease activity index but not between serum zinc concentration and this index. No association was found between zinc measurements and the presence or absence of fistulas, use of prednisone or sulfasalazine (Azulfidine), large bowel resections, and length of small bowel resected.

How the Erie Business Coalition for Health Care Cost Containment is progressing in its dealings with a highly traditional provider community to find solutions to the health cost problems of its mostly small employer-members; how the American Dental Association is responding to insurers' and others' encroachments on fee-for-service by promoting self-insured as the most cost-effective employee dental plans. These are follow-ups on stories that appeared previously in HCM.

As with affirmative action in the '70s, it is the big companies that have, in just the last 10 or 12 months, begun to address AIDS in the workplace. Their top executives have come to add such action to the list of management responsibilities. More employers of all sizes may join them, especially those that grasp the true role--and the non-role--of geography in the AIDS epidemic.

Health and life insurance, medical treatment and other costs associated with AIDS in the workplace are commanding attention, but what's known so far raises more questions than it answers. Regardless, potential expenditures are being used to justify public and private sector practices that ignore more important long-term issues.

As the science of low light level sensing becomes better understood, the demand for systems with this capability has increased considerably in recent years. Low light level television systems are part of these low light sensing devices in which interest has grown. Development of low light level TV systems has, in turn, stimulated technical advances in new tube types with improved performance, development of electronic techniques which enhance the over-all performance, and design techniques which make the system more versatile and adaptable. A general look at some of these developments and techniques gives insight into the versatility and adaptability of low light level TV.