Femoropopliteal In-stent Restenosis Repair: Midterm Outcomes After Paclitaxel Eluting Balloon Use (PLAISIR Trial).

OBJECTIVE: The aim was to assess 18 month outcomes of the paclitaxel eluting balloon (PEB) in patients with femoropopliteal (FP) in-stent restenosis (ISR). METHODS: In a national prospective and multicentre cohort study, symptomatic patients with femoropopliteal in-stent restenosis were included from January 2012 to June 2013. Patients were treated by paclitaxel eluting balloon angioplasty (In Pact Admiral, Medtronic, Santa Rosa, CA, USA). Clinical and duplex scan follow-up evaluations were performed at 1, 3, 6, 9, 12, and 18 months. The primary endpoint was freedom from target lesion revascularisation (TLR) at 12 months. Secondary endpoints were major adverse cardiovascular events (MACE), Target extremity revascularisation (TER), primary and secondary sustained clinical improvement, recurrent restenosis rate, primary and secondary patency, quality of life assessed by EQ-5D questionnaire, technical success, clinical success, and length of stay RESULTS: A total of 53 patients were enrolled. After a blinded review, 10 patients were defined as protocol violation because restenosis occurred more than 2 years after stent implantation. Procedures were performed in 55 limbs, 48 (87%) for claudication and 7 (13%) for critical limb ischaemia. The mean diameter and length of PEB were 6 ± 0.57 mm and 86 mm ± 32 mm, follow-up was 17 months (range 1-19). At 1 year, the survival rate was 96 ± 2.7% and freedom from TLR and TER were 90.2 ± 4.2% and 85 ± 5%, respectively. Sustained primary and secondary clinical improvements were 78.6 ± 5.7% and 92.0 ± 3.8%, respectively. At 1 year, the primary patency rate was 83.7 ± 5.0%. Prior to the procedure, the mean EQ-5D score was 66 ± 14 and 74 ± 16 at 1 year (p = .10). Two patients died during follow-up; one patient died 33 days after the procedure because of limb ischaemia. CONCLUSION: PEB for the treatment of FP ISR is associated with a low rate of re-interventions and restenosis. Clinical improvement is maintained at 18 months.

Differential gene expression of ewes varying in tolerance to dietary nitrate.

Ruminants consuming diets with increased concentrations of nitrate (NO(3)(-)) can accumulate nitrite (NO(2)(-)) in the blood, resulting in toxicity. In a previous experiment, ewes identified as highly tolerant to subacute dietary NO(3)(-) were able to consume greater amounts of NO(3)(-) than lowly tolerant ewes without exhibiting signs of toxicity. We hypothesized that highly tolerant and lowly tolerant ewes differ in their ability to metabolize NO(3)(-) and thereby differ in the expression of hepatic genes involved in NO(3)(-) metabolism. Therefore, our objective was to identify hepatic genes differentially expressed between ewes classified as lowly tolerant and highly tolerant after administration of a subacute quantity of dietary NO(3)(-). Analysis of the Bovine Oligonucleotide Microarray data identified 100 oligonucleotides as differentially expressed (P < 0.05) between lowly tolerant and highly tolerant ewes. Functional analysis of the genes associated with these oligonucleotides revealed 2 response clusters of interest: metabolic and stress. Genes of interest within these 2 clusters (n = 17) and nonclustered genes with the greatest fold changes (FC; n = 5) were selected for validation by real-time reverse-transcription PCR. Relative expression, genomic regulation, and FC agreed between microarray and real-time reverse-transcription-PCR analyses, and FC differences (P < 0.05) between lowly tolerant and highly tolerant ewes were confirmed for 12 genes. Metabolic genes that were downregulated (P ≤ 0.032) in lowly tolerant ewes vs. highly tolerant ewes included aldehyde oxidase 1, argininosuccinate lyase, putative steroid dehydrogenase, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase1, and sterol carrier protein 2. In contrast, the metabolic gene homeobox was upregulated (P = 0.037) in lowly tolerant ewes. The glutathione peroxidase 3 and inter-α (globulin) inhibitor H4 genes in the stress response cluster were upregulated (P ≤ 0.045) in lowly tolerant ewes. Genes with the greatest FC, but did not cluster within the functional analysis included haptoglobin, which was upregulated (P = 0.024) in lowly tolerant ewes, and fatty acid desaturase 2 and thyroid hormone responsive, both of which were downregulated (P ≤ 0.019) in lowly tolerant ewes. Results from this study indicate that hepatic gene expression differs in ewes identified as lowly tolerant and highly tolerant to increased dietary NO(3)(-).

A software tool for the graphical visualization of large and complex populations.

Pedigree drawing is an essential tool in genetic and genealogical studies. A genetic analysis of a disease often starts with drawing a pedigree to show the overall population structure, the relationship among individuals, and gene flows from generation to generation. Such a graphical presentation of a pedigree is valuable for understanding the nature of the disease such as inheritance mode and familial trends and of the disease, for tracing the source of a detrimental gene, and for identifying the founders of the population. A genealogy study typically requires a pedigree drawing to show relationships among individuals. However, as the size and complexity of a pedigree increase, drawing a clear pedigree becomes a challenge. Pedigraph has been created to solve this problem. We developed a software tool named Pedigraph capable of creating artistic graphical pedigree drawings of large and complex populations with flexible options for pedigree analysis. Preliminary tests show that this software tool has great potential to be a useful tool for research in breeding, genetics and genomics in plants, animals, and zoo species, as well as a useful tool for studying history and human populations.

Allelic variation and genetic linkage of avian microsatellites in a new turkey population for genetic mapping.

Efforts to build a comprehensive genetic linkage map for the turkey (Meleagris gallopavo) have focused on development of genetic markers and experimental resource families. In this study, PCR amplification was attempted for 772 microsatellite markers that had been previously developed for three avian species (chicken, quail and turkey). Allelic polymorphism at 410 markers (53.1% of total examined) was determined by genotyping ten individuals (six F1 parents and four grandparents) in a new resource population specifically developed for genetic linkage mapping. Of these 410 markers, 109 (26.6%) were polymorphic in the tested individuals, with an average of 2.3 alleles per marker. Higher levels of polymorphism were found for the turkey-specific markers (61.1%) than for the chicken (22.7%) or quail-specific markers (33.3%). To test the fidelity of the matings, demonstrate the power of these families for linkage analysis, and determine genetic linkage relationships, 86 polymorphic markers were genotyped for up to 224 birds including founder grandparents, parents and F2 progeny. Linkage relationships for many of the chicken markers elucidated in the turkey were comparable to those observed in the chicken. These data demonstrate that the new UMN/NTBF resource population will provide a solid foundation for constructing a comparative genetic map of the turkey.

Linkage analysis using direct and indirect counting and relative efficiencies for codominant and dominant loci.

A method based on direct and indirect counting is developed for rapid and accurate linkage analysis for codominant and dominant loci. Methods for estimating gender-specific recombination frequencies are available for cases where at least one of the two loci is multiallelic and for biallelic loci with mixed parental linkage phases where at least one locus is codominant. Most of the estimates of gender-average and gender-specific recombination frequencies required iterative solutions. The new method makes use of the full data set, yields exact estimates of the recombination frequencies when the observed and expected genotypic frequencies are equal, and are computationally efficient. Relative efficiency of various data types is affected by the inheritance mode and by parental linkage phases of biallelic loci, but unaffected by the locus polymorphism when using the full data set for linkage analysis. The ability to determine parental linkage phases is affected by the locus polymorphism as well as inheritance mode. Intercross (or F-2 design) is more efficient for mapping codominant loci, whereas backcross is more efficient if dominance is involved. Mixed parental linkage phases of biallelic loci are less efficient than coupling or repulsion linkage phases. Ignoring noninformative offspring results in biased estimates of recombination frequency for biallelic loci only and reduced LOD scores for all cases.

Expression of the telomerase catalytic subunit, hTERT, induces resistance to transforming growth factor beta growth inhibition in p16INK4A(-) human mammary epithelial cells.

Failures to arrest growth in response to senescence or transforming growth factor beta (TGF-beta) are key derangements associated with carcinoma progression. We report that activation of telomerase activity may overcome both inhibitory pathways. Ectopic expression of the human telomerase catalytic subunit, hTERT, in cultured human mammary epithelial cells (HMEC) lacking both telomerase activity and p16(INK4A) resulted in gaining the ability to maintain indefinite growth in the absence and presence of TGF-beta. The ability to maintain growth in TGF-beta was independent of telomere length and required catalytically active telomerase capable of telomere maintenance in vivo. The capacity of ectopic hTERT to induce TGF-beta resistance may explain our previously described gain of TGF-beta resistance after reactivation of endogenous telomerase activity in rare carcinogen-treated HMEC. In those HMEC that overcame senescence, both telomerase activity and TGF-beta resistance were acquired gradually during a process we have termed conversion. This effect of hTERT may model a key change occurring during in vivo human breast carcinogenesis.

The role of polyester patch angioplasty in carotid endarterectomy: a multicenter study.

The objectives of this study were to examine the morphology, restenosis, dilatation, and possible complications of polyester collagen impregnated carotid patches. Between March 1994 and January 1995, 207 patients (56 females and 151 males) undergoing 221 carotid endarterectomies (CE) with a collagen-impregnated knitted polyester patch were enrolled in a European prospective multicenter study. Patches were used for arteries deemed to be smaller than usual by visual inspection. General anesthesia was used in 201 procedures (91%), and a shunt was used in 76 procedures (34.4%). One hundred fourteen CE (51.6%) were checked by a perioperative arteriography or angioscopy. The diameter of the internal carotid artery (ICA) and carotid bulb (CB) were measured by duplex scan both preoperatively and every 6 months during follow-up. The main end point was carotid occlusion or restenosis, defined as a stenosis of 50% or more according to NASCET criteria. Carotid polyester-impregnated patches appear to be reliable. The patch was easy to cut and suture, and hemostasis was obtained immediately. No rupture occurred. However, the higher restenosis rate in women may restrict the use of polyester patch to men.

p57KIP2 expression and loss of heterozygosity during immortal conversion of cultured human mammary epithelial cells.

We have uncovered a novel role for the cyclin-dependent kinase inhibitor, p57KIP2, during the immortalization of cultured human mammary epithelial cells (HMECs). HMECs immortalized after chemical carcinogen exposure initially expressed little or no telomerase activity, and their telomeres continued to shorten with passage. Cell populations whose mean terminal restriction fragment (TRF) length declined to < or = 3 kb exhibited slow heterogeneous growth and contained many nonproliferative cells. These conditionally immortal HMEC cultures accumulated large quantities of p57 protein. With continued passage, the conditionally immortal cell populations very gradually converted to a fully immortal phenotype of good uniform growth, expression of high levels of telomerase activity, and stabilization of telomere length. The fully immortal HMECs that grew well did not accumulate p57 in G0 or during the cell cycle. DNA and RNA analysis of mass populations and individual subclones of conditionally immortal HMEC line 184A1 showed that continued growth of conditionally immortal cells with critically short telomeres was repeatedly accompanied by loss of the expressed p57 allele and transient expression of the allele imprinted previously. Conditionally immortal 184A1 with mean TRF > 3 kb, infected with retroviruses containing the p57 gene, exhibited premature slow heterogeneous growth. Conversely, exogenous expression of human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, in 184A1 with mean TRF > 3 kb prevented both the slow heterogeneous growth phase and accumulation of p57 in cycling populations. These data indicate that in HMECs that have overcome replicative senescence, p57 may provide an additional barrier against indefinite proliferation. Overcoming p57-mediated growth inhibition in these cells may be crucial for acquisition of the unlimited growth potential thought to be critical for malignant progression.

Viral oncogenes accelerate conversion to immortality of cultured conditionally immortal human mammary epithelial cells.

Our recent studies on the process of immortalization of cultured human mammary epithelial cells (HMEC) have uncovered a previously undescribed, apparently epigenetic step, termed conversion. When first isolated, clonally derived HMEC lines of indefinite lifespan showed little or no telomerase activity or ability to maintain growth in the presence of TGFbeta. Cell populations whose mean terminal restriction fragment length had declined to <3 kb also exhibited slow heterogeneous growth, and contained many non-proliferative cells. With continued passage, these conditionally immortal cell populations very gradually converted to a fully immortal phenotype of good growth+/-TGFbeta, expression of high levels of telomerase activity, and stabilization of telomere length. We now show that exposure of the early passage conditionally immortal 184A1 HMEC line to the viral oncogenes human papillomavirus type 16 (HPV16)-E6, -E7, or SV40T, results in either immediate (E6) or rapid (E7; SV40T) conversion of these telomerase negative, TGFbeta sensitive conditionally immortal cells to the fully immortal phenotype. Unlike conditional immortal 184A1, the HPV16-E7 and SV40T exposed cells were able to maintain growth in TGFbeta prior to expression of high levels of telomerase activity. A mutated HPV16-E6 oncogene, unable to inactivate p53, was still capable of rapidly converting conditional immortal 184A1. Our studies provide further evidence that the transforming potential of these viral oncogenes may involve activities beyond their inactivation of p53 and pRB functions. These additional activities may greatly accelerate a step in HMEC immortal transformation, conversion, that would be rate-limiting in the absence of viral oncogene exposure.

Gradual phenotypic conversion associated with immortalization of cultured human mammary epithelial cells.

Examination of the process of immortal transformation in early passages of two human mammary epithelial cell (HMEC) lines suggests the involvement of an epigenetic step. These lines, 184A1 and 184B5, arose after in vitro exposure of finite lifespan 184 HMEC to a chemical carcinogen, and both are clonally derived. Although early-passage mass cultures of 184A1 and 184B5 maintained continuous slow growth, most individual cells lost proliferative ability. Uniform good growth did not occur until 20-30 passages after the lines first appeared. Early-passage cultures expressed little or no telomerase activity and telomeres continued to shorten with increasing passage. Telomerase activity was first detected when the telomeres became critically short, and activity levels gradually increased thereafter. Early-passage cultures had little or no ability to maintain growth in transforming growth factor-beta (TGFbeta); however, both mass cultures and clonal isolates showed a very gradual increase in the number of cells displaying progressively increased ability to maintain growth in TGFbeta. A strong correlation between capacity to maintain growth in the presence of TGFbeta and expression of telomerase activity was observed. We have used the term "conversion" to describe this process of gradual acquisition of increased growth capacity in the absence or presence of TGFbeta and reactivation of telomerase. We speculate that the development of extremely short telomeres may result in gradual, epigenetic-based changes in gene expression. Understanding the underlying mechanisms of HMEC conversion in vitro may provide new insight into the process of carcinogenic progression in vivo and offer novel modes for therapeutic intervention.

Transforming growth factor beta stabilizes p15INK4B protein, increases p15INK4B-cdk4 complexes, and inhibits cyclin D1-cdk4 association in human mammary epithelial cells.

The effects of transforming growth factor beta (TGF-beta) were studied in closely related human mammary epithelial cells (HMEC), both finite-life-span 184 cells and immortal derivatives, 184A1S, and 184A1L5R, which differ in their cell cycle responses to TGF-beta but express type I and type II TGF-beta receptors and retain TGF-beta induction of extracellular matrix. The arrest-resistant phenotype was not due to loss of cyclin-dependent kinase (cdk) inhibitors. TGF-beta was shown to regulate p15INK4B expression at at least two levels: mRNA accumulation and protein stability. In TGF-beta-arrested HMEC, there was not only an increase in p15 mRNA but also a major increase in p5INK4B protein stability. As cdk4- and cdk6-associated p15INK4B increased during TGF-beta arrest of sensitive cells, there was a loss of cyclin D1, p21Cip1, and p27Kip1 from these kinase complexes, and cyclin E-cdk2-associated p27Kip1 increased. In HMEC, p15INK4B complexes did not contain detectable cyclin. p15INK4B from both sensitive and resistant cells could displace in vitro cyclin D1, p21Cip1, and p27Kip1 from cdk4 isolated from sensitive cells. Cyclin D1 could not be displaced from cdk4 in the resistant 184A1L5R cell lysates. Thus, in TGF-beta arrest, p15INK4B may displace already associated cyclin D1 from cdks and prevent new cyclin D1-cdk complexes from forming. Furthermore, p27Kip1 binding shifts from cdk4 to cyclin E-cdk2 during TGF-beta-mediated arrest. The importance of posttranslational regulation of p15INK4B by TGF-beta is underlined by the observation that in TGF-beta-resistant 184A1L5R, although the p15 transcript increased, p15INK4B protein was not stabilized and did not accumulate, and cyclin D1-cdk association and kinase activation were not inhibited.

Stability of tandem repeats in the Drosophila melanogaster Hsr-omega nuclear RNA.

The Drosophila melanogaster Hsr-omega locus produces a nuclear RNA containing > 5 kb of tandem repeat sequences. These repeats are unique to Hsr-omega and show concerted evolution similar to that seen with classical satellite DNAs. In D. melanogaster the monomer is approximately 280 bp. Sequences of 19 1/2 monomers differ by 8 +/- 5% (mean +/- SD), when all pairwise comparisons are considered. Differences are single nucleotide substitutions and 1-3 nucleotide deletions/insertions. Changes appear to be randomly distributed over the repeat unit. Outer repeats do not show the decrease in monomer homogeneity that might be expected if homogeneity is maintained by recombination. However, just outside the last complete repeat at each end, there are a few fragments of sequence similar to the monomer. The sequences in these flanking regions are not those predicted for sequences decaying in the absence of recombination. Instead, the fragmentation of the sequence homology suggests that flanking regions have undergone more severe disruptions, possibly during an insertion or amplification event. Hsr-omega alleles differing in the number of repeats are detected and appear to be stable over a few thousand generations; however, both increases and decreases in repeat numbers have been observed. The new alleles appear to be as stable as their predecessors. No alleles of less than approximately 5 kb nor more than approximately 16 kb of repeats were seen in any stocks examined. The evidence that there is a limit on the minimum number of repeats is consistent with the suggestion that these repeats are important in the function of the unusual Hsr-omega nuclear RNA.

The LGM Vena-Tech caval filter: results of a multicenter study.

Caval filters have proved essential to the progress being made in the prevention of recurrent pulmonary embolism. A prospective multicenter study was conducted to evaluate the efficacy and possible complications relating to the LGM Vena-Tech percutaneous caval filter, which has been used in Europe since 1989. A total of 222 patients who had undergone LGM Vena-Tech filter placement between September 1989 and December 1991 were included in this study. Two hundred twenty caval filters were positioned via the percutaneous route: 154 of them via the jugular or subclavian vein and 66 via the femoral vein. Two filters could not be implanted. The in-hospital mortality rate was 1.7% (four patients), which included one patient who died of intraoperative recurrent pulmonary embolism. Mean follow-up was 15 months. Forty-one patients died during follow-up (actuarial survival 65.4% +/- 6% at 30 months). There were five cases of recurrent pulmonary embolism (cumulative freedom from pulmonary embolism 93.2% +/- 3.8% at 30 months). Ten patients had thrombosis of the inferior vena cava (actuarial caval patency 94% +/- 3.6% at 30 months). Eight filters (3.6%) migrated over distances that were less than the height of one vertebra. Shifting did not lead to any cases of thrombosis or recurrent pulmonary embolism. Ten filters tilted between 15 and 25 degrees in relation to the inferior vena cava axis. Recurrent pulmonary embolism never occurred concurrently with filter tilting. The LGM Vena-Tech caval filter ensures satisfactory prevention of pulmonary embolism with a low rate of complications. However, because its long-term fate is not known, its use should be restricted to cases in which heparin treatment has failed or is contraindicated.

IMP-L2: an essential secreted immunoglobulin family member implicated in neural and ectodermal development in Drosophila.

The Drosophila IMP-L2 gene was identified as a 20-hydroxyecdysone-induced gene encoding a membrane-bound polysomal transcript. IMP-L2 is an apparent secreted member of the immunoglobulin superfamily. We have used deficiencies that remove the IMP-L2 gene to demonstrate that IMP-L2 is essential in Drosophila. The viability of IMP-L2 null zygotes is influenced by maternal IMP-L2. IMP-L2 null progeny from IMP-L2+ mothers exhibit a semilethal phenotype. IMP-L2 null progeny from IMP-L2 null mothers are 100% lethal. An IMP-L2 transgene completely suppresses the zygotic lethal phenotype and partially suppresses the lethality of IMP-L2 null progeny from IMP-L2 null mothers. In embryos, IMP-L2 mRNA is first expressed at the cellular blastoderm stage and continues to be expressed through subsequent development. IMP-L2 mRNA is detected in several sites including the ventral neuroectoderm, the tracheal pits, the pharynx and esophagus, and specific neuronal cell bodies. Staining of whole-mount embryos with anti-IMP-L2 antibodies shows that IMP-L2 protein is localized to specific neuronal structures late in embryogenesis. Expression of IMP-L2 protein in neuronal cells suggests a role in the normal development of the nervous system but no severe morphological abnormalities have been detected in IMP-L2 null embryos.

Wildlife jurisprudence.

The area of wildlife law is complex and confusing. Significant international and federal legislation concerning wildlife conservation is reviewed in this article. State regulation, wildlife rehabilitation, and extralabel drug use are briefly discussed.

The Drosophila Stubble-stubbloid gene encodes an apparent transmembrane serine protease required for epithelial morphogenesis.

The Stubble-stubbloid (Sb-sbd) gene is required for hormone-dependent epithelial morphogenesis of imaginal discs of Drosophila, including the formation of bristles, legs, and wings. The gene has been cloned by using Sb-sbd-associated DNA lesions in a 20-kilobase (kb) region of a 263-kb genomic walk. The region specifies an approximately 3.8-kb transcript that is induced by the steroid hormone 20-hydroxyecdysone in imaginal discs cultured in vitro. The conceptually translated protein is an apparent 786-residue type II transmembrane protein (N terminus in, C terminus out), including an intracellular N-terminal domain of at least 35 residues and an extracellular C-terminal trypsin-like serine protease domain of 244 residues. Sequence analyses indicate that the Sb-sbd-encoded protease could activate itself by proteolytic cleavage. Consistent with the cell-autonomous nature of the Sb-sbd bristle phenotype, a disulfide bond between cysteine residues in the noncatalytic N-terminal fragment and the C-terminal catalytic fragment could tether the protease to the membrane after activation. Both dominant Sb and recessive sbd mutations affect the organization of microfilament bundles during bristle morphogenesis. We propose that the Sb-sbd product has a dual function. (i) It acts through its proteolytic extracellular domain to detach imaginal disc cells from extracellular matrices, and (ii) it transmits an outside-to-inside signal to its intracellular domain to modify the cytoskeleton and facilitate cell shape changes underlying morphogenesis.

Expression of heat-shock locus hsr-omega in nonstressed cells during development in Drosophila melanogaster.

The hsr-omega locus forms one of the largest Drosophila heat-shock puffs and produces three major transcripts. These three transcripts are also produced constitutively, at lower levels, in almost all tissues and developmental stages. The amounts of the transcripts in nonstressed cells are modulated during development. The hormone ecdysone leads to increased levels of hsr-omega transcripts in cultured cells, suggesting that changing ecdysone titers may play a role in the developmental changes of hsr-omega transcript levels. By in situ hybridization to RNA in tissue sections, we detect only two cell types that lack hsr-omega transcripts--the preblastoderm embryo and the primary spermatocyte. There are no maternal transcripts of hsr-omega in the embryo. Transcripts appear abruptly at the time that the zygotic genome becomes transcriptionally active, shortly before the formation of the cellular blastoderm. No constitutive hsr-omega transcripts are found in primary spermatocytes. The spermatocytes cannot respond to heat shock by transcribing either hsr-omega or hsp70 RNA. Constitutive hsr-omega transcription is resumed later in spermatogenesis and hsr-omega RNA is detected in differentiating spermatids. These spermatids are also capable of mounting a heat-shock response, as measured by increases in hsr-omega and hsp70 RNA.

Hsr-omega, A Novel Gene Encoded by a Drosophila Heat Shock Puff.

Although originally identified because of its abundant transcription in heat shock, the hsr-omega gene is active, at generally lower levels, in non-stressed cells. The locus produces an unusual set of three transcripts. Evidence from a variety of experiments suggests that one of these transcripts acts in the nucleus, possibly to regulate the activity of a nuclear protein. Another of the transcripts appears to act in the cytoplasm, possibly monitoring or regulating some aspect of translation. The two transcripts together could have a role in coordinating nuclear and cytoplasmic activity. A number of processes occur in eukaryotic cells in which nuclear and cytoplasmic activities need to be coordinated; we suggest that hsr-omega plays a role in such coordination.

Multiple inducers of the Drosophila heat shock locus 93D (hsr omega): inducer-specific patterns of the three transcripts.

The Drosophila hsr omega locus produces one of the largest and most active heat shock puffs, yet it does not encode a heat shock protein. Instead, this locus produces a distinctive set of three transcripts, all from the same start site. The largest transcript, omega 1, is limited to the nucleus and appears to have a role there. A second nuclear transcript, omega 2, is produced by alternative termination and contains the sequence found in the 5' 20-25% of omega 1 (depending on the Drosophila species). The cytoplasmic transcript, omega 3, is produced by removal of a 700-bp intron from omega 2. All three hsr omega RNAs are produced constitutively and production is enhanced by heat shock. In addition to being a member of the set of heat shock puffs, the hsr omega puff is induced by agents that do not affect other heat shock loci, suggesting that hsr omega is more sensitive to environmental changes than other loci. We report here that agents that induce puffing of hsr omega loci in polytene nuclei also lead to an increase in hsr omega transcripts in diploid cells. We also show that the relative levels of omega 1 and omega 3 can be modulated independently by several agents. All drugs that inhibit translation, either initiation or elongation, stabilize the omega 3 transcript, which normally turns over within minutes in control cells. Drugs (such as benzamide and colchicine) that induce puffing of hsr omega, but not other heat shock loci, lead to large increases in omega 1. Although the constitutive level of omega 1 is relatively stable, the drug-induced excess is lost rapidly when the drug is withdrawn. The relative levels of hsr omega transcripts may reflect different states in cellular metabolism.