Climatic modelling of the distribution of the mahogany glider (Petaurus gracilis), and the squirrel glider (P. norfolcensis)

Known locality records of the mahogany glider (Petaurus gracilis) and the squirrel glider (Petaurus norfolcensis) in Queensland were used to predict the distributional limits of both of these species within Queensland using the computer program BIOCLIM. The mahogany glider was predicted to occur in areas with a higher average mean annual temperature, smaller temperature range, higher temperatures throughout the year, higher annual precipitation, higher seasonality of precipitation, higher seasonality of moisture index and higher precipitation in the wettest quarter and warmest quarter when compared with the predicted distribution of the squirrel glider. The squirrel glider has been recorded across a wider geographic area and its distribution had a larger variation in bioclimatic variables. The predicted distribution of the mahogany glider did not extend outside the known area on the mainland, although the species was predicted to occur over 500 m elevation in some areas within their known range. BIOCLIM did, however, predict that the mahogany glider might occur on Hinchinbrook Island and the Palm Islands. In contrast to the mahogany glider, the squirrel glider was predicted to occur well outside of its known distribution, including all that area predicted to be habitat for the former species. Despite this predicted overlap, the closest these two species are known to occur to each other is 25 km.

An automated image cytometry system for monitoring DNA ploidy and other cell features of radiotherapy and chemotherapy patients

DNA content and distribution in cell nuclei were studied in samples of fine-needle aspiration (FNA) from 27 locally advanced breast and head and neck cancers in two going randomized trials that compared accelerated fractionation to standard fractionation radiation in locally advanced breast cancer and head and neck cancer. Two image cytometry methods were compared: a new, fully automated DNA image cytometry system (AIC) and a conventional image cytometry (CIC) system with manual selection, focusing, and segmentation of cells. The results of both techniques were compared on the basis of DNA histogram parameters including DNA index (DI), mean DNA values (MDV), and Auer's DNA histogram patterns. An excellent correlation was achieved between the two imaging techniques in terms of DI (r=0.985, p<0.001) and MDV (r=0.951, p<0.001) as well as between Auer's histogram patterns, where both methods agreed completely. It was concluded in these analyses that the two image cytometry methods were equivalent. However, the AIC offered an advantage by scanning samples in a fully automated way, which represented significant time saving for cytopathologists working with the system, as well as a larger number of cells used in the automated analysis. With the automated image cytometer, 500 relevant cells were collected and analyzed in about 10 minutes, where with the interactive (manual) method, it took typically an hour to collect and analyze only about 250 cells. Seventeen samples were sufficient for flow analysis. Image cytometry and flow cytometry showed good agreement in DI determination; however, three cases reported as diploid by flow cytometry were found to be aneuploid by image cytometry techniques.

Synergistic activation of transcription by nuclear factor Y and sterol regulatory element binding protein

The current studies define the role of three distinct cis-elements in the proximal promoter of the rat farnesyl diphosphate (FPP) synthase gene. The three cis-elements, a sterol regulatory element 3 (SRE-3) flanked by an ATTGG motif (inverted CCAAT box), and a CCAAT box, form a sterol regulatory unit that is necessary and sufficient for sterol-regulated expression of FPP synthase promoter-reporter genes. FPP synthase promoter-reporter genes, that contain promoters with either wild-type nucleotide sequences or mutations in one or more of the three cis-elements, were transiently transfected into CV-1 cells. The activity of the wild-type promoter-reporter gene increased when the cells were incubated in sterol-depleted media or when the cells were co-transfected with a plasmid encoding the mature form of SRE binding protein (SREBP-1a). The results with the mutant promoter-reporter genes demonstrated that all three cis-elements were necessary for normal expression/regulation of the reporter gene by either sterols or by co-expressed SREBP-1a. Gel mobility shift assays demonstrated that the synergistic binding of SREBP-1a to SRE-3 was dependent on the binding of recombinant nuclear factor Y (NF-Y) to the DNA, consistent with the in vivo regulation studies.

An analysis of structural similarity in the iron and manganese superoxide dismutases based on known structures and sequences

There are two types of homologous enzymes catalysing the dismutation of the superoxide radical--Cu-Zn superoxide dismutases, and manganese or iron superoxide dismutases. In the latter two forms there is a high percentage of identity in the primary structures, and the tertiary structures are very similar particularly in the areas of the active site and in the residues responsible for the formation of the dimer. The quaternary structure of the dimer is also highly conserved. However, it has been found that despite this conservation there is strong metal ion specificity and many enzymes in the family will only be active if the correct metal ion is present. The purpose of this study has been to analyse solved X-ray structures for interactions common in both the manganese and iron forms and those that are specific to each, which may indicate reasons for the metal ion specificity. Initial analysis points to the probability that it is a combination of a number of residues, and not necessarily the same ones in every instance, which confer the specificity. In addition we have identified some anomalies in the currently available Fe/MnSOD structures which may require further remodelling and refinement.

cAMP stimulates osteoblast-like differentiation of calcifying vascular cells. Potential signaling pathway for vascular calcification

The role of the cAMP signaling pathway in vascular calcification was investigated using calcifying vascular cells (CVC) derived from primary aortic medial cell cultures. We previously showed that CVC have fibroblastic morphology and express several osteoblastic differentiation markers. After confluency, they aggregate into cellular condensations, which later mature into nodules where mineralization is localized. Here, we investigated the effects of cAMP on CVC differentiation because it plays a role in both osteoblastic differentiation and vascular disease. Dibutyryl-cAMP or forskolin treatment of CVC for 3 days induced osteoblast-like "cuboidal" morphology, inhibited proliferation, and enhanced alkaline phosphatase activity, all early markers of osteoblastic differentiation. Isobutylmethylxanthine and cholera toxin had the same effects. Treatment of CVC with pertussis toxin, however, did not induce the morphological change or increase alkaline phosphatase activity, although it inhibited CVC proliferation to a similar extent. cAMP also increased type I procollagen production and gene expression of matrix gamma-carboxyglutamic acid protein, recently shown to play a role in in vivo vascular calcification. cAMP inhibited the expression of osteopontin but did not affect the expression of osteocalcin and core binding factor. Prolonged cAMP treatment enhanced matrix calcium-mineral incorporation but inhibited the condensations resulting in diffuse mineralization throughout the monolayer of cells. Treatment of CVC with a protein kinase A-specific inhibitor, KT5720, inhibited alkaline phosphatase activity and mineralization during spontaneous CVC differentiation. These results suggest that the cAMP pathway promotes in vitro vascular calcification by enhancing osteoblast-like differentiation of CVC.

dally, a Drosophila glypican, controls cellular responses to the TGF-beta-related morphogen, Dpp

Decapentaplegic (Dpp) is a Drosophila member of the Transforming Growth Factor-beta (TGF-beta)/Bone Morphogenetic Protein (BMP) superfamily of growth factors. Dpp serves as a classical morphogen, where concentration gradients of this secreted factor control patterning over many cell dimensions. Regulating the level of Dpp signaling is therefore critical to its function during development. One type of molecule proposed to modulate growth factor signaling at the cell surface are integral membrane proteoglycans. We show here that division abnormally delayed (dally), a Drosophila member of the glypican family of integral membrane proteoglycans is required for normal Dpp signaling during development, affecting cellular responses to this morphogen. Ectopic expression of dally+ can alter the patterning activity of Dpp, suggesting a role for dally+ in modulating Dpp signaling strength. These findings support a role for members of the glypican family in controlling TGF-beta/BMP activity in vivo by affecting signaling at the cell surface.

Adjuvant radiotherapy and chemotherapy in node-positive premenopausal women with breast cancer

BACKGROUND

Radiotherapy after mastectomy to treat early breast cancer has been known since the 1940s to reduce rates of local relapse. However, the routine use of postoperative radiotherapy began to decline in the 1980s because it failed to improve overall survival. We prospectively tested the efficacy of combining radiotherapy with chemotherapy.

METHODS

From 1978 through 1986, 318 premenopausal women with node-positive breast cancer were randomly assigned, after modified radical mastectomy, to receive chemotherapy plus radiotherapy or chemotherapy alone. Radiotherapy was given to the chest wall and locoregional lymph nodes between the fourth and fifth cycles of cyclophosphamide, methotrexate, and fluorouracil.

RESULTS

After 15 years of follow-up, the women assigned to chemotherapy plus radiotherapy had a 33 percent reduction in the rate of recurrence (relative risk, 0.67; 95 percent confidence interval, 0.50 to 0.90) and a 29 percent reduction in mortality from breast cancer (relative risk, 0.71; 95 percent confidence interval, 0.51 to 0.99), as compared with the women treated with chemotherapy alone.

CONCLUSIONS

Radiotherapy combined with chemotherapy after modified radical mastectomy decreases rates of locoregional and systemic relapse and reduces mortality from breast cancer.

cut interacts with Notch and protein kinase A to regulate egg chamber formation and to maintain germline cyst integrity during Drosophila oogenesis

Communications between the germline and the soma during Drosophila oogenesis have been previously shown to be essential for the formation of egg chambers and to establish polarity in the developing oocyte. In this report, we demonstrate that the function of a somatically expressed gene, cut, is critical for maintaining the structural integrity of germline-derived cells and their arrangement within an egg chamber. Genetic manipulations of cut activity resulted in defective packaging of germline-derived cysts into egg chambers and disintegration of the structural organization of oocyte-nurse cell complexes to generate multinucleate germline-derived cells. We also found that cut interacts genetically with the Notch gene and with the catalytic subunit of Protein kinase A gene during egg chamber morphogenesis. Since cut expression is restricted to the somatic follicle cells and cut mutant germline clones are phenotypically normal, we propose that the defects in the assembly of egg chambers and the changes in germline cell morphology observed in cut mutant egg chambers are the result of altered interactions between follicle cells and germline cells. cut encodes a nuclear protein containing DNA-binding motifs, and we suggest that it participates in intercellular communications by regulating the expression of molecules that directly participate in this process.

A randomised trial of accelerated versus conventional radiotherapy in head and neck cancer

BACKGROUND AND PURPOSE

To study the effect of accelerated radiation treatment in locally advanced head and neck cancer, a prospective randomised trial was conducted comparing two fractionation schemes which differed only in the overall treatment time; fraction size and total dose were the same in both arms.

MATERIALS AND METHODS

Eighty-two patients with stage 3 or 4 squamous cell cancer of the oral cavity, oropharynx, hypopharynx or larynx considered suitable for radical radiotherapy as primary treatment were stratified by site and stage and randomised to receive 66 Gy in 33 2 Gy daily fractions in 45-48 days (o.d.) or 66 Gy in 33 2 Gy twice daily fractions in 22-25 days (b.i.d.).

RESULTS

An initial improved clinical response in tumour control in the b.i.d. arm was not sustained and the 3 year recurrence free survival and overall survival rates were similar and not significantly different. The actuarial recurrence free survival was 49.1% in the b.i.d. arm and 44.3% in the o.d. arm. The disease free 3 year survival was 59.4% and 56.8%, respectively. The acute and late normal tissue effects were scored using the RTOG scale. As expected the acute effects were much greater in the b.i.d. arm. The combined grade 3 and 4 late effects were similar but the proportion of grade 4 reactions was significantly higher in the b.i.d. arm. The increase in grade 4 toxicity caused the trial to be discontinued after 82 of the planned 226 patients had been randomised.

CONCLUSIONS

The severity of the normal tissue effects and a failure to demonstrate sustained local control does not support this fractionation scheme in patients with such extensive head and neck cancer.

Identification of glycerol-3-phosphate acyltransferase as an adipocyte determination and differentiation factor 1- and sterol regulatory element-binding protein-responsive gene

We demonstrate that the mRNA levels of glycerol-3-phosphate acyltransferase (GPAT), a mitochondrial enzyme catalyzing the initial step in glycerolipid synthesis, are induced during the differentiation of 3T3-L1 preadipocytes to adipocytes and following ectopic expression of rat adipocyte determination and differentiation factor 1 (ADD1), a protein with high homology to the human sterol regulatory element-binding protein-1 (SREBP-1). The increase in GPAT mRNA levels that occurs during differentiation is partially prevented by ectopic expression of a dominant negative form of ADD1. Nucleotide sequences corresponding to the proximal promoter of the murine mitochondrial GPAT gene (Jerkins, A. A., Liu, W. R., Lee, S., and Sul, H. S. (1995) J. Biol. Chem. 270, 1416-1421) bound SREBP-1a and NF-Y in electromobility shift assays. In addition, GPAT promoter-luciferase reporter genes were stimulated by co-expression of SREBP-1a. This increase was attenuated when either a dominant negative form of NF-Y was co-transfected into the cells or when the GPAT promoter contained mutations in the putative binding sites for SREBP-1a or NF-Y. These studies demonstrate that the regulated expression of the mitochondrial GPAT gene requires both NF-Y and ADD1/SREBPs. Thus, SREBPs/ADD1 regulate not only genes involved in cholesterol homeostasis and fatty acid synthesis but also a key enzyme in glycerolipid synthesis.

Clinical use of asymmetric collimators

PURPOSE

To illustrate some of the radiation treatment techniques with asymmetric collimators in one field dimension.

METHODS AND MATERIALS

Treatment planning for various sites is done with an in-house developed treatment planning system. Dose distributions in the central plane are illustrated.

RESULTS

The use of asymmetric collimation, in addition to being a replacement for cerrobend and lead blocks, can facilitate treatment setup with boost fields and with half-beam asymmetric fields as in matching two adjacent fields, in avoiding nearby critical organ or tissue, and in tangential breast treatment. The use of asymmetric collimators would alter the dose distribution across the radiation field and should be accounted for during treatment planning. In conjunction with arc rotation or multiple asymmetric fields, two-dimensional conformal radiotherapy is possible.

CONCLUSION

The full potential of asymmetric collimation requires the use of a proper treatment planning algorithm. Some of the treatment techniques with asymmetric collimation in one field dimension are shown here.

Lentiviral genomes with G-to-A hypermutation may result from Taq polymerase errors during polymerase chain reaction

Retroviral genomes with a high frequency of G-to-A mutations are thought to originate during reverse transcription. Here we show that bursts of G-to-A mutation may also occur during DNA synthesis by Taq polymerase on a simian immunodeficiency proviral template. These G-to-A changes tend to occur at GpA and, to a lesser extent, GpG dinucleotides. Because the resulting sequences are like previously reported hypermutant human and simian immunodeficiency virus (HIV and SIV) genomes, it is important to design experiments that can clearly discriminate between Taq and reverse transcripts errors in studies of lentiviral G-to-A hypermutation.

Synergistic binding of sterol regulatory element-binding protein and NF-Y to the farnesyl diphosphate synthase promoter is critical for sterol-regulated expression of the gene

Sterol-regulated transcription of the farnesyl diphosphate (FPP) synthase gene is dependent on two cis elements in the proximal promoter. These elements, an inverted CCAAT box and sterol regulatory element 3 (SRE-3), bind NF-Y and sterol regulatory element-binding protein 1 (SREBP-1), respectively. We now demonstrate that the binding of recombinant SREBP-1 to its cognate site (SRE-3) within the FPP synthase promoter in vitro is enhanced by binding of NF-Y to the upstream inverted CCAAT box. Using an FPP synthase promoter fragment containing the binding sites for both NF-Y and SREBP-1 in gel mobility shift assays, we demonstrate that the addition of NF-Y increases the binding of SREBP-1 to SRE-3 over 20-fold. In contrast, NF-Y does not stimulate the binding of SREBP-1 to SRE-3 when the inverted CCAAT box is either mutated or 4 base pairs (bp) are inserted between the inverted CCAAT box and SRE-3. Promoter-reporter genes, containing either the wild-type FPP synthase promoter sequence or containing the 4-bp insertion between the inverted CCAAT box and SRE-3, were transiently transfected into cells. The activity of the wild-type promoter-reporter gene increased when the cells were either incubated in sterol-depleted medium or were co-transfected with an expression vector encoding transcriptionally active SREBP-1. This increase in activity was attenuated when the promoter contained the 4-bp insert, consistent with defective binding of SREBP to the promoter in vivo. These studies suggest that the binding of SREBP-1 to SRE-3 in the FPP synthase promoter, and subsequent stimulation of transcription, is dependent on synergistic binding and a functional interaction between SREBP-1 and NF-Y.

Late cosmetic results of short fractionation for breast conservation

BACKGROUND AND PURPOSE

The number of fractions of radiation therapy (RT) used after breast conserving surgery varies widely and accounts for a significant proportion of the workload in a modern radiotherapy department. Internationally, 'standard' therapy ranges from 3 to 7 weeks of daily treatment with or without a boost. Short RT schedules have the attraction of reducing workload but raise concern about an increased risk of late effects and poorer cosmetic outcome.

MATERIALS AND METHODS

In a randomized trial, 186 women with T1 or T2, pathologically node-negative breast cancer had cosmetic and various normal tissue effects data collected prospectively. The breast RT prescription was 44 Gy in 16 daily fractions to a tangent pair.

RESULTS

Median follow-up is 6.7 years. Actuarial 5-year breast recurrence was 6%. Overall cosmetic results at 5 years were good or excellent in 89% and 96% as reported by physicians and patients, respectively, and were stable between 2 and 5 years. Breast discomfort, erythema, edema and induration were related to both surgery and RT. At 5 years, 20% had breast discomfort, 18% had induration, 6% had erythema and 3% had some degree of breast edema. Fewer patients had these effects at 5 years than immediately after primary surgery. The presence of induration prior to starting RT was associated with a greater likelihood of breast induration 3 or more years following RT (P = 0.02). Thirteen percent of patients, generally those with large breasts, developed mild inframammary telangiectasia by 5 years.

CONCLUSIONS

Results are comparable to those reported from centers employing more conventional fractionation. Short fractionation produces acceptable cosmetic results for the majority of women if there are no contraindications to RT and in the absence of significant post-operative breast induration.

Effect of acetylsalicylic acid on radiation and cosmetic results after conservative surgery for early breast cancer: a randomized trial

BACKGROUND AND PURPOSE

Acetylsalicylic acid (ASA) can reduce the incidence of stroke and myocardial infarction by inhibiting platelet-fibrin thrombi in small blood vessels. To determine if ASA could reduce late effects of radiation therapy mediated by damage to small blood vessels, a prospective, placebo-controlled, double-blind trial was conducted in women with early breast cancer, receiving radiotherapy to the conserved breast.

MATERIALS AND METHODS

Cosmetic outcome and late radiotherapy effects were recorded prospectively for 186 women with T1 or T2, pathologically node-negative breast cancer treated with breast conservation and randomized to receive ASA (325 mg daily) or placebo for 1 year from the start of radiation therapy. Radiation was a tangent pair to the breast alone delivering a modal dose of 44 Gy in 16 daily fractions in 22-25 days.

RESULTS

Median follow-up is 6.5 years. The use of ASA has not had any effect on the acute (erythema, edema or discomfort) or late (induration, telangiectasia) effects of radiotherapy (all P > 0.10), the patients' or physicians' assessment of the cosmetic outcome (all P > 0.25) or rates of breast recurrence (P > 0.25).

CONCLUSION

ASA cannot be recommended to improve the outcome of radiotherapy complementing breast conserving surgery.

Evaluation of a coagulase-negative variant of Staphylococcus aureus as a cause of intramammary infections in a herd of dairy cattle

A coagulase-negative variant of Staphylococcus aureus was identified in a herd of 250 lactating dairy cows. During testing of the entire herd, this strain of S aureus was isolated from aseptically collected milk samples of 25 cows. Cows with intramammary infections attributable to coagulase-negative S aureus had an increased somatic cell count in their milk, which was indicative of mastitis infection. Speciation of the Staphylococcus organisms was made, using a series of biochemical tests. A strain of a coagulase-positive S aureus also caused intramammary infections in the herd and shared identical biochemical characteristics with the coagulase-negative strain. Moreover, both strains could not be typed by the use of the International Set of Bovine Phages. Analysis of these findings indicated that a coagulase-negative variant of S aureus can cause intramammary infections in cattle, coagulase-negative variants of S aureus that cause mastitis can be more prevalent in herds than coagulase-positive variants, and clinicians should avoid misclassifying coagulase-negative S aureus as organisms that are clinically unimportant.

Role for sterol regulatory element binding protein in the regulation of farnesyl diphosphate synthase and in the control of cellular levels of cholesterol and triglyceride: evidence from sterol regulation-defective cells

In order to define the factors involved in the regulation of farnesyl diphosphate (FPP) synthase, we used sterol regulation-defective (SRD) cell lines that constitutively express either high (SRD-2) or low (SRD-6) levels of transcriptionally active sterol regulatory element binding protein (SREBP). FPP synthase mRNA levels were high in SRD-2 cells and low in SRD-6 cells and were unaffected by the addition or removal of sterols from the media. In contrast, the mRNA levels in parental CHO-7 cells were regulated by sterols. SRD-2, SRD-6, and CHO-7 cells were also transiently transfected with plasmids containing FPP synthase promoter-reporter genes. Reporter gene activity was significantly higher in SRD-2 cells than in either SRD-6 or CHO-7 cells, consistent with a higher rate of transcription of the reporter gene in SRD-2 cells. The high expression of the reporter gene in SRD-2 cells was not observed when the FPP synthase promoter contained a three base pair mutation within an SREBP binding site, termed sterol regulatory element-3 (SRE-3). These observations are consistent with the hypothesis that high levels of transcription of the FPP synthase gene are dependent on the availability of transcriptionally active SREBP. We also demonstrate that the incorporation of radioactive acetate into both cholesterol and fatty acids was enhanced in SRD-2 cells as compared to CHO-7 or SRD-6 cells. Finally, we demonstrate that the concentrations of cholesterol, cholesteryl ester, and triglyceride were all significantly elevated in SRD-2 cells. We conclude that SREBP is involved not only in the regulation of FPP synthase and cholesterogenesis but also in fatty acid and triglyceride synthesis.

Heterogeneity in human tumour hypoxic fraction using the comet assay

The alkaline comet assay has previously been used to estimate the fraction of radiobiologically hypoxic cells in tumours from patients undergoing palliative radiotherapy for advanced breast and head and neck cancer. Results obtained from fine needle aspirate biopsies (FNABs) using this method indicate considerable heterogeneity in hypoxic fraction between tumours. Heterogeneity between 3 aspirates taken from the same 10 tumours immediately following single doses of 3.5 to 5 Gy is now examined. Results indicate that a single fine needle aspirate is reasonably representative for DNA damage and DNA content. However, difficulties were encountered in obtaining an adequate sample of tumour cells after the final radiation treatment. The average hypoxic fraction decreased from 14% after the first dose to 9% after the last dose, and in 3 tumours which could be evaluated after both the first and last fraction, the hypoxic fraction decreased in two but increased in the third. Rejoining of DNA strand breaks was observed between sequential aspirates indicating that pooling of samples for analysis may not be advisable using this method.

Teaching dietary counseling skills to residents: patient and physician outcomes. The CADRE Study Group

Our objective was to determine whether an educational intervention and prompting intervention for physicians improved dietary counseling of patients with high blood cholesterol and resulted in beneficial changes in patients' diets and cholesterol levels. We instituted a factorial design, multicenter, randomized, placebo-controlled trial to test two interventions. We tested the trial at continuity care clinics of internal medicine residents at seven community and university medical centers in the northern and eastern United States. Our participants were 130 internal medicine residents and 254 adult outpatients with blood cholesterol levels of 240-300 mg/dL. Interventions included an educational program for resident physicians designed to improve their skills and confidence in dietary counseling (two one-hour sessions with specially prepared printed materials for use in counseling) and a prompting intervention, which was a fingerstick blood cholesterol determination prior to the patient's clinic visit. Resident physicians' knowledge, attitudes, and self-reported behaviors were assessed prior to the intervention and 10 months later using chart audits and questionnaires. Residents' behaviors were also assessed by exit interviews with patients. Patients' knowledge, attitudes, behaviors, and fingerstick blood cholesterol levels were measured at baseline and 10 months later. The educational program increased the percentage of physicians who were confident in providing effective dietary counseling (baseline of 26% to 67%-78%; P < .01). The prompting intervention approximately doubled the frequency of physician counseling (P = .0005) and increased the likelihood that patients would try to change their diets. When both interventions were combined, most outcomes were better, although not statistically significant. Cholesterol levels, however, decreased only marginally and were no different among groups at 10-month follow-up. Despite success in changing physicians' attitudes and behaviors and increasing patients' willingness to change their diets, there was no significant change in patients' cholesterol levels. Medical Subject Headings (MeSH): randomized controlled trial; cholesterol; patient education; behavior therapy; education, medical; diet.

Neurologic complications following bone marrow transplantation for sickle cell disease

A boy with sickle cell anemia underwent bone marrow transplantation (BMT). He was normal on neurological examination, but had radiologic evidence of an old left frontal lobe infarct, multiple cerebral vascular stenoses and moyamoya collaterals. After BMT he developed seizures with extension of the infarct and subarachnoid hemorrhage. One year later angiography revealed worsening stenosis of the M1 segments of both middle cerebral arteries. At that time an increase in von Willebrand's factor with decreased large molecular weight multimers (LvWF) was observed. We speculate that LvWF dependent, shear-induced platelet aggregation, together with endothelial damage may have contributed to the development of neurologic complications in this patient.

Sterol regulatory element binding protein binds to a cis element in the promoter of the farnesyl diphosphate synthase gene

Sterol-regulated transcription of the gene for rat farnesyl diphosphate (FPP) synthase (geranyl-diphosphate:isopentenyl-diphosphate geranyltranstransferase, EC 2.5.1.10) is dependent in part on the binding of the ubiquitous transcription factor NF-Y to a 6-bp element within the proximal promoter. Current studies identify a second element in this promoter that is also required for sterol-regulated transcription in vivo. Mutation of three nucleotides (CAC) within this element blocks the 8-fold induction of FPP synthase promoter-reporter genes that normally occurs when the transfected cells are incubated in medium deprived of sterols. Gel mobility-shift assays demonstrate that the transcriptionally active 68-kDa fragment of the sterol regulatory element (SRE-1)-binding protein assays (SREBP-1) binds to an oligonucleotide containing the wild-type sequence but not to an oligonucleotide in which the CAC has been mutated. DNase 1 protection pattern (footprint) analysis indicates that SREBP-1 binds to nucleotides that include the CAC. Both the in vivo and in vitro assays are affected by mutagenesis of nucleotides adjacent to the CAC. Coexpression of SREBP with a wild-type FPP synthase promoter-reporter gene in CV-1 cells results in very high levels of reporter activity that is sterol-independent. In contrast, the reporter activity remained low when the promoter contained a mutation in the CAC trinucleotide. We conclude that sterol-regulated transcription of FPP synthase is controlled in part by the interaction of SREBP with a binding site that we have termed SRE-3. Identification of this element may prove useful in the identification of other genes that are both regulated by SREBP and involved in lipid biosynthesis.

NF-Y has a novel role in sterol-dependent transcription of two cholesterogenic genes

The transcription of farnesyl diphosphate (FPP) synthase is regulated up to 30-fold by the sterol status of the cell. Point mutations in a 6-base pair ATTGGC sequence in the promoter disrupt both sterol-dependent transcription in vivo as well as binding of the transcription factor NF-Y in vitro. Co-transfection of cells with NF-YA29, a dominant negative form of NF-Y, and various promoter-reporter genes specifically inhibits the sterol-dependent regulation of FPP synthase and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase. In contrast, NF-YA29 does not affect the regulation of reporter genes under the control of promoters derived from either the HMG-CoA reductase or the low density lipoprotein receptor gene. Transient expression of the 68-kDa transcriptionally active fragment of sterol regulatory element-binding protein in cells stimulates an HMG-CoA synthase-reporter gene over 90-fold. This induction is blocked in cells co-expressing NF-YA29. We hypothesize that NF-Y plays a novel role in sterol-dependent regulation of two key genes in the cholesterol biosynthetic pathway and that this role requires a specific interaction with the sterol regulatory element-binding protein or related transcription factors.