Methylation and silencing of the retinoic acid receptor-beta2 gene in breast cancer

BACKGROUND

A growing body of evidence supports the hypotheses that the retinoic acid receptor beta2 (RAR-beta2) gene is a tumor suppressor gene and that the chemopreventive effects of retinoids are due to induction of RAR-beta2. RAR-beta2 expression is reduced in many malignant tumors, and we examined whether methylation of RAR-beta2 could be responsible for this silencing.

METHODS

RAR-beta2 expression was studied by reverse transcription-polymerase chain reaction (RT-PCR) analysis in eight breast cancer cell lines that were either treated with the demethylating agent 5-aza-2'-deoxycytidine and subsequently with all-trans-retinoic acid (ATRA) or left untreated. Sodium bisulfite genomic sequencing was used to determine the locations of 5-methylcytosines in the RAR-beta2 genes of three of these cell lines. In 16 breast cancer biopsy specimens and non-neoplastic breast tissue, methylation-specific PCR was used to determine the methylation status of RAR-beta2, and, in 13 of the specimens, RT-PCR analysis was used to detect RAR-beta2 expression.

RESULTS

Cell lines SK-BR-3, T-47D, ZR-75-1, and MCF7 exhibited expression of RAR-beta2 only after demethylation and treatment with ATRA. The first exon expressed in the RAR-beta2 transcript was methylated in cell lines ZR-75-1 and SK-BR-3. Six breast cancer specimens showed methylation in the same region of the gene. No expression of RAR-beta2 was found in any grade III lesion. An inverse association between methylation and gene expression was found in all grade II lesions. The RAR-beta2 gene from non-neoplastic breast tissue was unmethylated and expressed.

CONCLUSIONS

Methylation of the RAR-beta2 gene may be an initial step in breast carcinogenesis; treatment of cancer patients with demethylating agents followed by retinoic acid may offer a new therapeutic modality.

A PPARgamma mutant serves as a dominant negative inhibitor of PPAR signaling and is localized in the nucleus

The peroxisomal proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily that act as ligand-activated transcription factors. PPARgamma plays a critical role in regulating adipocyte differentiation and lipid metabolism. Recently, thiazolidinedione (TZD) and select non-TZD antidiabetic agents have been identified as PPARgamma agonists. To further characterize this receptor subclass, a mutant hPPARgamma lacking five carboxyl-terminal amino acids was produced (hPPARgamma2Delta500). In COS-1 cells transfected with PPAR-responsive reporter constructs, the mutant receptor could not be activated by a potent PPARgamma agonist. When cotransfected with hPPARgamma2 or hPPARalpha, hPPARgamma2Delta500 abrogated wild-type receptor activity in a dose-responsive manner. hPPARgamma2Delta500 was also impaired with respect to binding of a high-affinity radioligand. In addition, its conformation was unaffected by normally saturating concentrations of PPARgamma agonist as determined by protease protection experiments. Electrophoretic mobility shift assays demonstrated that hPPARgamma2Delta500 and hPPARgamma2 both formed heterodimeric complexes with human retinoidxreceptor alpha (hRXRalpha) and could bind a peroxisome proliferator-responsive element (PPRE) with similar affinity. Therefore, hPPARgamma2Delta500 appears to repress PPAR activity by competing with wild type receptor to dimerize with RXR and bind the PPRE. In addition, the mutant receptor may titrate out factors required for PPAR-regulated transcriptional activation. Both hPPARgamma2 and hPPARgamma2Delta500 localized to the nucleus of transiently transfected COS-1 cells as determined by immunofluorescence using a PPARgamma-specific antibody. Thus, nuclear localization of PPARgamma occurs independently of its activation state. The dominant negative mutant, hPPARgamma2Delta500, may prove useful in further studies to characterize PPAR functions both in vitro and in vivo

Therapeutic dilemma: the use of anticonvulsants in HIV-positive individuals

ARTICLE ABSTRACT: The concurrent use of anticonvulsants and antiretrovirals is a poorly studied area that poses a therapeutic dilemma for the clinician caring for HIV-positive patients requiring both classes of medications. Anticonvulsants and antiretrovirals may interact through multiple mechanisms including competition for protein binding, enhanced or reduced liver metabolism, and increased viral replication. The authors present many of the challenges faced by clinicians caring for HIV-positive patients who may require anticonvulsant therapy.

Microsculpture of the wing surface in Odonata: evidence for cuticular wax covering

The insect wing membrane is usually covered by scales, hairs, and acanthae, which serve diverse functions, such as species-specific coloration pattern, decrease of wind resistance during flight or decrease of wing wettability. Representatives of Palaeoptera (Odonata and Ephemeroptera) have no hairy structures on the wing membrane, but both its sides are fine-sculptured. In this study, the nature of the wing covering was studied using acoustic microscopy, scanning- and transmission electron microscopy followed by a variety of chemical treatments. It was shown that wing microsculptures are not cuticular outgrowths, but a wax covering, which is similar to pruinosity, which has been previously described in several odonate taxa. Data from scanning acoustic microscopy revealed that scratches on the wax covering have material density different from the surrounding material. Various functions of the wax covering are discussed.

Expression of retinoic acid receptors in non-neoplastic epithelial disorders of the vulva and normal vulvar skin

Retinoids and their nuclear retinoic receptors (RARs) are important modulators of epidermal cell proliferation and terminal differentiation. Aberrant expression of RARs in the epidermis has been found to be associated with altered differentiation capacity of keratinocytes. In this study, the expression of the various types of RARs (RAR-alpha, RAR-beta, and RAR-gamma) was investigated in surgical specimens from 17 patients with vulvar lichen sclerosus, 12 patients with vulvar squamous cell hyperplasia, and 11 specimens of normal vulvar skin by nonradioactive in situ hybridization. The results demonstrate that RAR-alpha expression is significantly decreased in lichen sclerosus (p < 0.0001) and squamous cell hyperplasia (p = 0.007) compared with normal vulvar skin. Furthermore, in normal vulvar skin RAR-alpha mRNA is mainly located in the suprabasal epidermal cell layers, whereas in lichen sclerosus RAR-alpha is expressed predominantly in the basal cell layers. In squamous cell hyperplasia RAR-alpha expression occurs in all cell layers. Compared with normal vulvar skin, RAR-gamma expression is higher in lichen sclerosus (p = 0.026), but no statistically significant differences are seen in squamous cell hyperplasia. These results suggest that partial loss and abnormal localization of RAR-alpha expression as well as increased RAR-gamma expression may play a role in the etiology of non-neoplastic epithelial disorders of the vulva.

cDNA cloning and analysis of tissue-specific expression of mouse peroxisomal straight-chain acyl-CoA oxidase

Straight-chain acyl-CoA oxidase is the first and rate limiting enzyme in the peroxisomal beta-oxidation pathway catalysing the desaturation of acyl-CoAs to 2-trans-enoyl-CoAs, thereby producing H2O2. To study peroxisomal beta-oxidation we cloned and characterized the cDNA of mouse peroxisomal acyl-CoA oxidase. It consists of 3778 bp, including a 1983-bp ORF encoding a polypeptide of 661 amino-acid residues. Like the rat and human homologue the C-terminus contains an SKL motif, an import signal present in several peroxisomal matrix proteins. Sequence analysis revealed high amino-acid homology with rat (96%) and human (87%) acyl-CoA oxidase in addition to minor homology ( approximately 40%) with other related proteins, such as rabbit trihydroxy-cholestanoyl-CoA oxidase, human branched chain acyl-CoA oxidase and rat trihydroxycoprostanoyl-CoA oxidase. Acyl-CoA oxidase mRNA and protein expression were most abundant in liver followed by kidney, brain and adipose tissue. During mouse brain development acyl-CoA oxidase mRNA expression was highest during the suckling period indicating that peroxisomal beta-oxidation is most critical during this developmental stage. Comparing tissue mRNA levels of peroxisome proliferator-activated receptor alpha and acyl-CoA oxidase, we noticed a constant relationship in all tissues investigated, except heart and adipose tissue in which much more, and respectively, much less, peroxisome proliferator-activated receptor alpha mRNA in proportion to acyl-CoA oxidase mRNA was found. Our data show that acyl-CoA oxidase is an evolutionary highly conserved enzyme with a distinct pattern of expression and indicate an important role in lipid metabolism.

Activation of peroxisome proliferator-activated receptor gamma does not inhibit IL-6 or TNF-alpha responses of macrophages to lipopolysaccharide in vitro or in vivo

We have investigated the potential use of peroxisome proliferator-activated receptor gamma (PPARgamma) agonists as anti-inflammatory agents in cell-based assays and in a mouse model of endotoxemia. Human peripheral blood monocytes were treated with LPS or PMA and a variety of PPARgamma agonists. Although 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) at micromolar concentrations significantly inhibited the production of TNF-alpha and IL-6, four other high affinity PPARgamma ligands failed to affect cytokine production. Similar results were obtained when the monocytes were allowed to differentiate in culture into macrophages that expressed significantly higher levels of PPARgamma or when the murine macrophage cell line RAW 264.7 was used. Furthermore, saturating concentrations of a potent PPARgamma ligand not only failed to block cytokine production, but also were unable to block the inhibitory activity of 15d-PGJ2. Thus, activation of PPARgamma does not appear to inhibit the production of cytokines by either monocytes or macrophages, and the inhibitory effect observed with 15d-PGJ2 is most likely mediated by a PPARgamma-independent mechanism. To examine the anti-inflammatory activity of PPARgamma agonists in vivo, db/db mice were treated with a potent thiazolidinedione that lowered their elevated blood glucose and triglyceride levels as expected. When thiazolidinedione-treated mice were challenged with LPS, they displayed no suppression of cytokine production. Rather, their blood levels of TNF-alpha and IL-6 were elevated beyond the levels observed in control db/db mice challenged with LPS. Comparable results were obtained with the corresponding lean mice. Our data suggest that compounds capable of activating PPARgamma in leukocytes will not be useful for the treatment of acute inflammation.

Activation of PPARalpha or gamma reduces secretion of matrix metalloproteinase 9 but not interleukin 8 from human monocytic THP-1 cells

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that directly control numerous genes of lipid metabolism by binding to response elements in the promoter. It has recently been proposed that PPARgamma may also regulate genes for proinflammatory proteins, not through PPRE binding but by interaction with transcription factors AP-1, STAT, and NF-kappaB. Recent studies with cultured human monocytes, however, have failed to observe an inhibitory effect of PPARgamma agonists on induced expression of TNFalpha and IL-6, genes known to be controlled by AP-1, STAT, and NF-kappaB. In a similar fashion, we show here that PPARalpha (fenofibrate) or PPARgamma (rosiglitazone) agonists failed to modulate LPS-induced secretion of IL-8 in THP-1 cells. When we made parallel observations on another gene, matrix metalloproteinase 9 (MMP-9), we were surprised to find profound downregulation of LPS-induced secretion by both PPARalpha or PPARgamma agonists. These findings suggest that PPAR may regulate only a subset of the proinflammatory genes controlled by AP-1, STAT, and NF-kappaB. Effects of PPARs on MMP-9 may account for the beneficial effect of PPAR agonists in animal models of atherosclerosis.

Effect of daily iron supplementation on iron status, cell-mediated immunity, and incidence of infections in 6-36 month old Togolese children

OBJECTIVE

To assess the impact of a daily oral iron supplementation on hematological status, cell-mediated immunity and susceptibility to infections in children living in an environment where iron deficiency, malaria and other infections are frequent.

DESIGN

Randomized, double-blind iron supplementation including a placebo group.

SETTING

A village in Togo, West Africa.

SUBJECTS

Of the 229 6-36-month-old children of both sexes recruited, 197 with hemoglobin concentration >/=80 g/l were included and 163 completed the study.

INTERVENTION

Children received daily a placebo (n=79) or a dose of 2-3 mg of elemental iron per kg of body weight (n=84) for 3 months. Hematological, nutritional and immune status were assessed at the beginning and at the end of the supplementation period, and 6 months later. Morbidity was recorded throughout the study.

RESULTS

Iron supplementation had a significant and positive effect on iron status of children and no impact on the incidence of infections, especially malaria. Its probable effect on immune status was masked by interference of infections and their treatment, which contributed to improve hematological and immune status in both groups.

CONCLUSION

According to the negative consequences of anemia and iron deficiency on global child development, control of iron deficiency by oral iron supplementation in young children has to be conducted, associated with prophylaxis and treatment of malaria and repeated deworming.

SPONSORSHIP

Program supported by IRD. European Journal of Clinical Nutrition (2000) 54, 29-35

Pneumothorax post CT-guided lung biopsy: a comparison between detection on chest radiographs and CT

Pneumothorax is reported to be a more common complication of lung biopsy performed under computed tomography (CT) than under fluoroscopic guidance. This may simply reflect the greater sensitivity of CT over chest radiographs (CXRs) in the detection of small pneumothoraces. This study aimed to determine the incidence of pneumothorax detected by CXR and by CT after CT-guided biopsy of non-pleurally based pulmonary masses, and to compare these incidences with previous reports in the literature of pneumothorax incidence post fluoroscopic biopsy. 88 consecutive CT-guided lung biopsies of masses not abutting the pleural surface were included. Immediate post-biopsy CT images, and 1 and 4 h CXRs were assessed independently by two observers for the presence and size of pneumothorax. 72 biopsies were fine needle aspirations (FNAs) performed with 22 G spinal needles only, seven were cutting needle biopsies (CNBs) performed with 18 G cutting needles only, and nine were both. 37 patients (42%) developed a pneumothorax. 35 were detected on CT (40%) and 22 on CXR (25%). None required tube drainage. Of the patients in whom CT demonstrated a pneumothorax, the average depth of this was significantly greater for those in whom CXR also detected a pneumothorax compared with those in whom CXR was negative (7.3 mm versus 3.4 mm, p < 0.05). The incidence of pneumothorax detected on CXR post CT-guided biopsy is similar to the reported incidence post fluoroscopic biopsy.

Characterization of a novel, antifungal, chitin-binding protein from Streptomyces tendae Tü901 that interferes with growth polarity

The afp1 gene, which encodes the antifungal protein AFP1, was cloned from nikkomycin-producing Streptomyces tendae Tü901, using a nikkomycin-negative mutant as a host and screening transformants for antifungal activity against Paecilomyces variotii in agar diffusion assays. The 384-bp afp1 gene has a low G+C content (63%) and a transcription termination structure with a poly(T) region, unusual attributes for Streptomyces genes. AFP1 was purified from culture filtrate of S. tendae carrying the afp1 gene on the multicopy plasmid pIJ699. The purified protein had a molecular mass of 9,862 Da and lacked a 42-residue N-terminal peptide deduced from the nucleotide sequence. AFP1 was stable at extreme pH values and high temperatures and toward commercial proteinases. AFP1 had limited similarity to cellulose-binding domains of microbial plant cell wall hydrolases and bound to crab shell chitin, chitosan, and cell walls of P. variotii but showed no enzyme activity. The biological activity of AFP1, which represents the first chitin-binding protein from bacteria exhibiting antifungal activity, was directed against specific ascomycetes, and synergistic interaction with the chitin synthetase inhibitor nikkomycin inhibited growth of Aspergillus species. Microscopy studies revealed that fluorescein-labeled AFP1 strongly bound to the surface of germinated conidia and to tips of growing hyphae, causing severe alterations in cell morphogenesis that gave rise to large spherical conidia and/or swollen hyphae and to atypical branching.

Health care trends in today's marketplace

As the year 2000 approaches, it is apparent that employer-sponsored health plans will again begin to experience high rate increases. Employers will need to utilize an up-to-date benefits philosophy and health plan purchasing strategy coupled with monitoring tools and vendor performance guarantees to deal with the situation. While many of the cost drivers are beyond an employer's control, taking a preemptive strike at health care inflation through design, cost sharing and other focused initiatives will minimize its impact.

A novel member of murine Polycomb-group proteins, Sex comb on midleg homolog protein, is highly conserved, and interacts with RAE28/mph1 in vitro

The Polycomb group of (PcG) genes were originally described in Drosophila, but many PcG genes have mammalian homologs. Genetic studies in flies and mice show that mutations in PcG genes cause posterior transformations caused by failure to maintain repression of homeotic loci, suggesting that PcG proteins have conserved functions. The Drosophila gene Sex comb on midleg (Scm) encodes an unusual PcG protein that shares motifs with the PcG protein polyhomeotic, and with a Drosophila tumor suppressor, lethal(3)malignant brain tumor (l(3)mbt). Expressed sequence tag (EST) databases were searched to recover putative mammalian Scm homologs, which were used to screen murine cDNA libraries. The recovered cDNA encodes two mbt repeats and the SPM domain that characterize Scm, but lacks the cysteine clusters and the serine/threonine-rich region found at the amino terminus of Scm. Accordingly, we have named the gene Sex comb on midleg homolog 1 (Scmh1). Like their Drosophila counterparts, Scmh1 and the mammalian polyhomeotic homolog RAE28/mph1 interact in vitro via their SPM domains. We analyzed the expression of Scmh1 and rae28/mph1 using northern analysis of embryos and adult tissues, and in situ hybridization to embryos. The expression of Scmh1 and rae28/mph1 is well correlated in most tissues of embryos. However, in adults, Scmh1 expression was detected in most tissues, whereas mph1/rae28 expression was restricted to the gonads. Scmh1 is strongly induced by retinoic acid in F9 and P19 embryonal carcinoma cells. Scmh1 maps to 4D1-D2.1 in mice. These data suggest that Scmh1 will have an important role in regulation of homeotic genes in embryogenesis and that the interaction with RAE28/mph1 is important in vivo.

Anthropogenic extinction of top carnivores and interspecific animal behaviour: implications of the rapid decoupling of a web involving wolves, bears, moose and ravens

The recent extinction of grizzly bears (Ursus arctos) and wolves (Canis lupus) by humans from 95-99% of the contiguous USA and Mexico in less than 100 years has resulted in dramatically altered and expanded prey communities. Such rampant ecological change and putative ecological instability has not occurred in North American northern boreal zones. This geographical variation in the loss of large carnivores as a consequence of anthropogenic disturbance offers opportunities for examining the potential consequences of extinction on subtle but important ecological patterns involving behaviour and interspecific ecological interactions. In Alaska, where scavengers and large carnivores are associated with carcasses, field experiments involving sound playback simulations have demonstrated that at least one prey species, moose (Alces alces), is sensitive to the vocalizations of ravens (Corvus corax) and may rely on their cues to avoid predation. However, a similar relationship is absent on a predator-free island in Alaska's Cook Inlet and at two sites in the Jackson Hole region of the Rocky Mountains (USA) where grizzly bears and wolves have been extinct for 50-70 years. While prior study of birds and mammals has demonstrated that prey may retain predator recognition capabilities for thousands of years even after predation as a selective force has been relaxed, the results presented here establish that a desensitization in interspecific responsiveness can also occur in less than ten generations. These results affirm (i) a rapid decoupling in behaviour involving prey and scavengers as a consequence of anthropogenic-caused predator-prey disequilibriums, and (ii) subtle, community-level modifications in terrestrial ecosystems where large carnivores no longer exist. If knowledge about ecological and behavioural processes in extant systems is to be enhanced, the potential effects of recently extinct carnivores must be incorporated into current programmes.

Ultrasound detection of pneumothorax

OBJECTIVE

To determine the accuracy of ultrasound in the detection of pneumothorax.

METHODS

Prospective blinded study comparing ultrasound, CT and radiographic findings in 29 patients following 41 CT-guided lung biopsies. Ultrasound examination of the chest was limited to the biopsy needle entry site.

RESULTS

Thirteen patients developed a post-biopsy pneumothorax demonstrated by CT. Seven of these were detected by ultrasound and six were visible on erect chest radiographs. Six of the 13 pneumothoraces were not detected by ultrasound, but five of these were loculated away from the biopsy needle entry site and were therefore in areas not examined during the limited ultrasound examination. There were no false-positive diagnoses of pneumothorax using ultrasound. The positive predictive value for ultrasound was 100% and the negative predictive value was 82%.

CONCLUSION

In this patient group, ultrasound was more sensitive than erect chest radiography in the detection of pneumothorax. Both have a specificity of 100%. This study suggests that ultrasound may prove valuable in pneumothorax detection when rapid conventional radiography is not possible or practical, and in circumstances where ultrasound is readily available, such as during ultrasound-guided interventional procedures.

Inhibition of adipocyte differentiation by HIV protease inhibitors

Patients with AIDS who are receiving therapy with HIV protease inhibitors have been widely reported to be afflicted with a syndrome characterized by lipodystrophy (fat redistribution favoring the accumulation of abdominal and cervical adipose tissue), hyperlipidemia, and insulin resistance. HIV protease inhibitors have been suggested to have a direct role in modulating adipocyte differentiation. To address this hypothesis, several HIV protease inhibitors were studied for their ability to either augment or inhibit the differentiation of murine 3T3-L1 preadipocytes. Dose-responsive inhibition of adipogenesis by several protease inhibitors was noted as measured by reduced triglyceride accumulation and attenuated induction of three differentiation marker genes -- aP2, lipoprotein lipase, and Adipo Q. Potential mechanisms for altered adipocyte function, including direct binding to PPARgamma or inhibition of PPARgamma-mediated gene transcription were effectively excluded.

Expression of the adhesion molecules CD49d and CD49e on G-CSF-mobilized CD34+ cells of patients with solid tumors or non-Hodgkin's and Hodgkin's lymphoma and of healthy donors is inversely correlated with the amount of mobilized CD34+ cells

The yield of CD34+ PBPC and colony-forming units-granulocyte-macrophage (CFU-GM) in leukapheresis products and the expression of the adhesion molecules CD11a, CD31, CD49d, CD49e, CD54, CD58, CD62L, c-kit (CD117), Thy-1 (CD90), CD33, CD38, and HLA-DR on CD34+ PBPC were analyzed in patients with cancer of the testis (n = 10), breast cancer (n = 10), Hodgkin's disease (n = 20), high-grade (n = 20) and low-grade (n = 20) non-Hodgkin's lymphoma, and healthy donors (n = 20) undergoing G-CSF (filgrastim)-stimulated PBPC mobilization. For each disease entity, G-CSF was administered in two different doses, 10 microg G-CSF/kg body weight (BW)/day s.c. vs. 24 microg G-CSF/kg BW s.c./day in steady-state condition. Data were compared for each dose group separately. Patients with cancer of the testis and breast cancer mobilized significantly more CD34+ cells than patients with high-grade and low-grade non-Hodgkin's lymphoma and Hodgkin's disease (p<0.05). Correspondingly, expression of CD49d on CD34+ PBPC was significantly lower in the same patients with cancer of the testis compared with high-grade and low-grade non-Hodgkin's lymphoma and Hodgkins' disease and in patients with breast cancer compared with high-grade and low-grade non-Hodgkin's lymphoma, Hodgkins's disease, and healthy donors. Similar results were obtained for CD49e. These data suggest that the expression of the adhesion molecules CD49d and CD49e on G-CSF-mobilized CD34+ cells of patients with solid tumors, non-Hodgkin's lymphoma, Hodgkin's disease, and healthy donors is inversely correlated with the amount of mobilized CD34+ cells.

The four murine peroxisomal ABC-transporter genes differ in constitutive, inducible and developmental expression

Four ATP-binding cassette (ABC) half-transporters have been identified in mammalian peroxisomes: adrenoleukodystrophy protein (ALDP), adrenoleukodystrophy-related protein (ALDRP), 70-kDa peroxisomal membrane protein (PMP70) and PMP70-related protein (P70R). Inherited defects in ALDP cause the neurodegenerative disorder X-linked adrenoleukodystrophy (X-ALD). By comparative Northern blot analyses we found each of the four murine peroxisomal ABC transporter mRNA species at maximum abundance only in a few tissues, which differed for each family member. The four genes were also regulated differentially during mouse brain development: ALDP mRNA was most abundant in embryonic brain and gradually decreased during maturation; ALDRP and P70R mRNA accumulated in the early postnatal period; and the amount of PMP70 transcript increased slightly during the second and third postnatal week. The different expression patterns could explain why beta-oxidation is defective in X-ALD, although ALDRP and PMP70 can replace ALDP functionally in fibroblasts. Dietary fenofibrate had no effect on the ALD and P70R genes, but strongly increased expression of the ALDR and PMP70 genes in mouse liver. However, in P-glycoprotein Mdr1a-deficient mice fenofibrate treatment increased ALDR gene expression also in the brain, suggesting that the multidrug-transporter P-glycoprotein restricts entry of fenofibrate to the brain at the blood-brain barrier. Analysis of the promoter sequences revealed a cryptic nuclear hormone receptor response element of the DR+4 type in the ALDR promoter and a novel 18-bp sequence motif present only in the 5' flanking DNA of the ALDR and PMP70 genes. The mouse ALDR gene uses a single transcription start site but alternative polyadenylation sites. These data are of importance for the use of ALDP-deficient mice as a model in pharmacological gene therapy studies.

The human homolog of Sex comb on midleg (SCMH1) maps to chromosome 1p34

Polycomb group genes were originally identified in Drosophila as repressors required to maintain the silenced state of homeotic loci. About ten Polycomb group genes have been cloned in Drosophila, and mammalian homologs have been identified for most of these. Here, we isolate cDNAs encoding two isoforms of a human homolog of Drosophila Sex comb on midleg (Scm), named Sex comb on midleg homolog-1 (SCMH1). Overall, SCMH1 has 94% identity to its mouse counterpart Scmh1, and 41% identity to Scm, and contains two 1(3)mbt domains, and the SPM domain that are characteristic of Scm. SCMH1 is widely expressed in adult tissues, and maps to chromosome 1p34.

[Evidence-based medicine--a critical overview]

BACKGROUND

Evidence-based medicine (EBM) is a strategy for the standardization of medical decision-making. The purpose of this review was to demonstrate the most important tools of EBM and to critically appraise them.

METHODS

The current literature concerning the subject is reviewed. A clinical example for the systematic use of EBM in diagnostic tests is explained in detail.

RESULTS

The risk of an increasing bureaucratic hindrance of medical procedures by EBM is weighed against the advantages of a systematic strategy for the valid assessment of medical information. According to the clinical example EBM proves to be a valuable tool in the quantitative estimation of residual risk and reliability of diagnostic tests in everyday clinical practice.

CONCLUSION

The critical use of the systematic tools of EBM for clinical decision-making is recommended.

Benefit of abciximab in patients with refractory unstable angina in relation to serum troponin T levels. c7E3 Fab Antiplatelet Therapy in Unstable Refractory Angina (CAPTURE) Study Investigators

BACKGROUND

In patients with refractory unstable angina, the platelet glycoprotein IIb/IIIa-receptor antibody abciximab reduces the incidence of cardiac events before and during coronary angioplasty. We investigated whether serum troponin T levels identify patients most likely to benefit from therapy with this drug.

METHODS

Among 1265 patients with unstable angina who were enrolled in the c7E3 Fab Antiplatelet Therapy in Unstable Refractory Angina (CAPTURE) trial, serum samples drawn at the time of randomization to abciximab or placebo were available from 890 patients; we used these samples for the determination of troponin T and creatine kinase MB levels. Patients with postinfarction angina were not included.

RESULTS

Serum troponin T levels at the time of study entry were elevated (above 0.1 ng per milliliter) in 275 patients (30.9 percent). Among patients receiving placebo, the risk of death or nonfatal myocardial infarction was related to troponin T levels. The six-month cumulative event rate was 23.9 percent among patients with elevated troponin T levels, as compared with 7.5 percent among patients without elevated troponin T levels (P<0.001). Among patients treated with abciximab, the respective six-month event rates were 9.5 percent for patients with elevated troponin T levels and 9.4 percent for those without elevated levels. As compared with placebo, the relative risk of death or nonfatal myocardial infarction associated with treatment with abciximab in patients with elevated troponin T levels was 0.32 (95 percent confidence interval, 0.14 to 0.62; P=0.002). The lower event rates in patients receiving abciximab were attributable to a reduction in the rate of myocardial infarction (odds ratio, 0.23; 95 percent confidence interval, 0.12 to 0.49; P<0.001). In patients without elevated troponin T levels, there was no benefit of treatment with respect to the relative risk of death or myocardial infarction at six months (odds ratio, 1.26; 95 percent confidence interval, 0.74 to 2.31; P=0.47).

CONCLUSIONS

The serum troponin T level, which is considered to be a surrogate marker for thrombus formation, identifies a high-risk subgroup of patients with refractory unstable angina suitable for coronary angioplasty who will particularly benefit from antiplatelet treatment with abciximab.