One-year survival following early revascularization for cardiogenic shock

CONTEXT

Cardiogenic shock (CS) is the leading cause of death for patients hospitalized with acute myocardial infarction (AMI).

OBJECTIVE

To assess the effect of early revascularization (ERV) on 1-year survival for patients with AMI complicated by CS.

DESIGN

The SHOCK (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) Trial, an unblinded, randomized controlled trial from April 1993 through November 1998.

SETTING

Thirty-six referral centers with angioplasty and cardiac surgery facilities.

PATIENTS

Three hundred two patients with AMI and CS due to predominant left ventricular failure who met specified clinical and hemodynamic criteria.

INTERVENTIONS

Patients were randomly assigned to an initial medical stabilization (IMS; n = 150) group, which included thrombolysis (63% of patients), intra-aortic balloon counterpulsation (86%), and subsequent revascularization (25%), or to an ERV group (n = 152), which mandated revascularization within 6 hours of randomization and included angioplasty (55%) and coronary artery bypass graft surgery (38%).

MAIN OUTCOME MEASURES

All-cause mortality and functional status at 1 year, compared between the ERV and IMS groups.

RESULTS

One-year survival was 46.7% for patients in the ERV group compared with 33.6% in the IMS group (absolute difference in survival, 13.2%; 95% confidence interval [CI], 2.2%-24.1%; P<.03; relative risk for death, 0.72; 95% CI, 0.54-0.95). Of the 10 prespecified subgroup analyses, only age (<75 vs >/= 75 years) interacted significantly (P<.03) with treatment in that treatment benefit was apparent only for patients younger than 75 years (51.6% survival in ERV group vs 33.3% in IMS group). Eighty-three percent of 1-year survivors (85% of ERV group and 80% of IMS group) were in New York Heart Association class I or II.

CONCLUSIONS

For patients with AMI complicated by CS, ERV resulted in improved 1-year survival. We recommend rapid transfer of patients with AMI complicated by CS, particularly those younger than 75 years, to medical centers capable of providing early angiography and revascularization procedures.

Cytotoxic effect of gossypol on colon carcinoma cells

Gossypol, a male contraceptive drug extracted from cottonseeds, has been found to have antiproliferative activity on tumour cells and is thought to be a potential anticancer drug. The aim of this study was to investigate the mechanisms of gossypol-induced cell death on two colon carcinoma cell lines, HT29 and LoVo. Firstly, we studied the effect of gossypol on the colony forming ability of these tumour cells, which is the main target of chemotherapeutic drugs. Using clonogenic assays, flow cytometry and DNA gel electrophoresis techniques, we have found that gossypol not only inhibited colony forming ability of these tumour cells, but we also observed cellular internucleosomal DNA fragmentation in the cells treated with 3 doses of gossypol and this was accompanied by the appearance of a sub-G1 apoptotic peak and morphological characteristics of apoptosis. Our results suggest that the gossypol induced cell death is via an apoptotic pathway and the effect of gossypol may not be cell cycle specific. Using Western blotting analysis, we found that the gossypol-induced apoptosis may not be involved in the regulation of p53 but possibly associated with the regulation of bcl-2 and Bax expression. Our evidence indicates that gossypol may provide a potential therapeutic benefit for the treatment of colon carcinoma and understanding the mechanisms of gossypol-induced cytotoxicity on tumour cells is essential for including this drug in clinical use.

Cutting edge: B cell linker protein is dispensable for the allelic exclusion of immunoglobulin heavy chain locus but required for the persistence of CD5+ B cells

The pre-B cell receptor (pre-BCR) and the BCR are required for B lymphopoiesis and for the allelic exclusion of Ig genes. Mice lacking B cell linker (BLNK) protein that is a component of the BCR signaling pathway have impaired B cell development. In this report, we show that allelic exclusion is intact in BLNK(-/-) mice harboring a V(H)12 transgene. This differs from mice lacking the tyrosine kinase Syk that is upstream of BLNK in BCR signaling and contrasts with mice lacking SLP-76 that is the equivalent adaptor molecule in TCR-signal transduction. We also show that, whereas most wild-type V(H)12-expressing B cells are CD5(+), the majority of the splenic V(H)12-expressing BLNK(-/-) B cells are CD5(-). A small population of V(H)12-expressing, BLNK(-/-) CD5(+) B cells is detectable in the peritoneal cavity of younger but not older mice. This suggests that BLNK deficiency affects not only the generation but also the persistence of B-1 cells.

Effects of elevated [CO(2)] and nitrogen nutrition on cytokinins in the xylem sap and leaves of cotton

We measured the level of xylem-derived cytokinins (CKs) entering a cotton leaf, and the CK levels in the same leaf, thus enabling xylem sap and foliar CKs to be compared concurrently. Although zeatin was the dominant CK in xylem sap, zeatin, dihydrozeatin, and N(6)-(2-isopentenyl) adenine were present in approximately equimolar levels in leaves. Elevated [CO(2)] (EC) has an effect on the levels of cytokinins in sap and leaf tissues. This effect was modulated by the two levels of root nitrogen nutrition (2 and 12 mM nitrate). Growth enhancement (70%) in EC over plants in ambient [CO(2)] (AC) was observed for both nitrogen nutrition treatments. Low-nitrogen leaves growing in EC exhibited photosynthetic acclimation, whereas there was no sign of photosynthetic acclimation in high-nitrogen grown leaves. Under these prevailing conditions, xylem sap and leaf tissues were obtained for CK analysis. Higher nitrogen nutrition increased the delivery per unit leaf area of CKs to the leaf at AC. EC caused a greater increase in CK delivery to the leaf at low nitrogen conditions (106%) than at high nitrogen conditions (17%). EC induced a significant increase in CK content in low-nitrogen leaves, whereas CK content in leaf tissues was similar for high-nitrogen leaves growing in AC and EC.

Differential diagnosis of Hb EE and Hb E-beta(0)-thalassemia by protein and DNA analyses

DNA analysis was used to confirm the Hb EE genotype and to differentiate from the possible genotype of Hb E-beta(0)-thalassemia in two Malay patients. The first patient was a 13-year-old Malay girl, whose parents were available for family studies. The second patient was a 69-year-old Malay woman with no living family members. The presence of Hb E in both propositi was confirmed by: (1) its characteristic electrophoretic mobilities on alkaline/acid gels; (2) its chromatographic properties on anion/cation exchangers, and (3) its mildly insoluble properties. However, differential diagnosis of Hb EE and Hb E-beta(0)-thalassemia was challenging in these two cases. In the former, this was because of the possible interactions of the parents' phenotypes; i.e., the mother had a similar phenotype. In the latter, it was due to the lack of any living family members for family studies. In this communication, we present the protein and DNA analyses, including data on the use of the restriction enzyme Mnl I, for the definitive diagnosis of the Hb EE genotype in the propositi of these two Malay families.

Angiographic findings and clinical correlates in patients with cardiogenic shock complicating acute myocardial infarction: a report from the SHOCK Trial Registry. SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK?

OBJECTIVES

We sought to delineate the angiographic findings, clinical correlates and in-hospital outcomes in patients with cardiogenic shock (CS) complicating acute myocardial infarction.

BACKGROUND

Patients with CS complicating acute myocardial infarction carry a grave prognosis. Detailed angiographic findings in a large, prospectively identified cohort of patients with CS are currently lacking.

METHODS

We compared the clinical characteristics, angiographic findings, and in-hospital outcomes of 717 patients selected to undergo angiography and 442 not selected, overall and by shock etiology: left or right ventricular failure versus mechanical complications.

RESULTS

Patients who underwent angiography had lower baseline risk and a better hemodynamic profile than those who did not. Overall, 15.5% of the patients had significant left main lesions on angiography, and 53.4% had three-vessel disease, with higher rates of both for those with ventricular failure, compared with patients who had mechanical complications. Among patients who underwent angiography, those with ventricular failure had significantly lower in-hospital mortality than patients with mechanical complications (45.2% vs. 57.0%; p = 0.021). Importantly, for patients with ventricular failure, in-hospital mortality also correlated with disease severity: 35.0% for no or single-vessel disease versus 50.8% for three-vessel disease. Furthermore, mortality was associated with the culprit lesion location (78.6% in left main lesion, 69.7% in saphenous vein graft lesions, 42.4% in circumflex lesions, 42.3% in left anterior descending lesions, and 37.4% in right coronary artery lesions), and Thrombolysis In Myocardial Infarction (TIMI) flow grade (46.5% in TIMI 0/1, 49.4% in TIMI 2 and 26% in TIMI 3).

CONCLUSIONS

Patients who underwent angiographic study in the SHOCK Trial Registry had a more benign cardiac risk profile, more favorable hemodynamic findings and lower in-hospital mortality than those for whom angiograms were not obtained. Patients with CS caused by ventricular failure had more severe atherosclerosis, and a different distribution of culprit vessel involvement but lower in-hospital mortality, than those with mechanical complications. Overall in-hospital survival correlates with the extent of coronary artery obstructions, location of culprit lesion and baseline coronary TIMI flow grade.

Variation in the oxygen isotope ratio of phloem sap sucrose from castor bean. Evidence in support of the Péclet effect

Theory suggests that the level of enrichment of (18)O above source water in plant organic material (Delta) may provide an integrative indicator of control of water loss. However, there are still gaps in our understanding of the processes affecting Delta. One such gap is the observed discrepancy between modeled enrichment of water at the sites of evaporation within the leaf and measured enrichment of the leaf water as a whole (Delta(L)). Farquhar and Lloyd (1993) suggested that this may be caused by a Péclet effect. It is also unclear whether organic material formed in the leaf reflects enrichment of water at the sites of evaporation within the leaf or Delta(L). To investigate this question castor bean (Ricinus communis L.) leaves, still attached to the plant, were sealed into a controlled-environment gas exchange chamber and subjected to a step change in leaf-to-air vapor pressure difference. Sucrose was collected from a cut on the petiole of the leaf in the chamber under equilibrium conditions and every hour for 6 h after the change in leaf-to-air vapor pressure difference. Oxygen isotope composition of sucrose in the phloem sap (Delta(suc)) reflected modeled Delta(L). A model is presented describing Delta(suc) at isotopic steady state, and accounts for 96% of variation in measured Delta(suc). The data strongly support the Péclet effect theory.

Regulation of telomerase activity by gamma-radiation in nasopharyngeal carcinoma cells

Since telomerase has been suggested to play a role in radiation response, the effect of radiation on the regulation of telomerase activity was studied on two NPC cell lines, CNE1 and 915. In order to investigate the correlation between cell survival and telomerase activity, three low doses (0.25, 0.5 and 1 Gy) and three high doses (2, 4 and 8 Gy) of gamma-radiation were used. We found that low doses of radiation induced telomerase activity (up to 250% of untreated controls) followed by a cell cycle G1 arrest, suggesting that the up-regulation of telomerase may play a role in initiating radiation induced cell cycle arrest. High doses of radiation resulted in decreased telomerase activity (down to 30% of untreated controls) and this was followed by an increased cell death. Our results indicate that the up-regulation of telomerase activity is an important response to radiation induced sub-lethal DNA damage. Our results also suggest that inhibition of telomerase activity by high doses of radiation may play a role radiation-induced cell death.

Cisplatin-induced p53-independent growth arrest and cell death in cancer cells

In a recent study, it was shown that DNA damaging agent cisplatin-induced growth arrest and cell death in cancer cells by a pathway sharing some of the characteristics of replicative senescence. The aim of this study was to determine the role of p53, p21WAF1 and p16INK4A proteins in this alternative route to cancer cell death in additional human cancer cell lines. After exposure to cisplatin, all the cell lines underwent growth arrest and expressed the senescence marker senescence-associated beta-galactosidase, but showed none of the features of apoptosis. However, there was no change in p53 protein expression, and neither p21WAF1 nor p16INK4A was expressed before or up to 4 days after cisplatin exposure. These findings provide further evidence that cells carrying mutations resulting in loss of function in the p53 gene can be killed by cisplatin via a p53-independent route with some similarities to replicative senescence, but not apoptosis.

Synthesis of C-11 methyl-substituted benzocycloheptapyridine inhibitors of farnesyl protein transferase

[formula: see text] Synthesis of C-11 methyl-substituted benzocycloheptylpyridine tricyclic compounds has been achieved via two different methods. Methylation of C-11 has been effected by treatment of amine 4 with BuLi followed by Mel quenching. In a similar procedure, introduction of a C-11 substituent with concomitant rearrangement of the exocyclic double bond has been carried out. Potent farnesyl protein transferase inhibitors have been synthesized using the above methodologies.

Establishing an immortalized human osteoprecursor cell line: OPC1

The present studies evaluated the feasibility of establishing a conditionally immortalized osteoprecursor cell line derived from human fetal bone tissue. Primary cultures were transfected with a plasmid in which the Mx-1 promoter drives the expression of SV40 T-antigen when activated by human A/D interferon. Several neomycin (G418)-resistant colonies were characterized for cell growth and alkaline phosphatase (ALP) enzyme activity. The clone, designated OPC1 (osteoblastic precursor cell line 1), which exhibited the highest ALP enzyme activity at passage 10 (P10), was selected for additional osteogenic phenotypic characterization. Reverse transcription-polymerase chain reaction (RT-PCR) phenotyping revealed abundant mRNA for osteocalcin (OC), osteonectin (ON), osteopontin (OP), parathyroid hormone receptor (PTHr), ALP, and procollagen type I (ProI). In addition, the levels of quantitative RT-PCR product of ON, OP, PTHr, and ProI mRNAs exhibited a marked up-regulation when maintained in medium containing an osteogenic supplement (OS). The ability to stimulate osteogenic differentiation was characterized in postconfluent OPC1 cells maintained in tissue culture medium supplemented with recombinant human bone morphogenetic protein-2 (rhBMP-2) either with or without an OS. All treatment groups exhibited a striking up-regulation of ALP enzyme activity that coincided with ALP histochemical observations. Postconfluent cells also exhibited the ability to form mineralized nodules under all treatments (confirmed by von Kossa histochemical staining and calcium deposition). An enzyme immunosorbent assay (EIA) was utilized to measure intact human OC from the OPC1 line under the various treatments. Abundant OC was evident in the tissue culture medium indicating de novo sythesis and release from the OPC1 line under appropriate conditions. The clonal human-derived OPC1 line represents a homogeneous osteogenic cell line that not only has maintained a consistent bone phenotype from P10 to at least P30, but has also exhibited the capacity to generate programmed differentiation in the presence of low dose rhBMP-2 (10 ng/ml). Thus, the OPC1 line is a human-derived osteoprecursor that provides a sensitive in vitro cell culture system to evaluate bone development, cell/biomaterial interactions, and may be a useful screen for putative bone differentiating factors.

Isolation of subgenus B adenovirus during a fatal outbreak of enterovirus 71-associated hand, foot, and mouth disease in Sibu, Sarawak

BACKGROUND

In mid-1997, several children died in Sarawak, Malaysia, during an epidemic of enterovirus-71 (EV71) hand, foot, and mouth disease. The children who died had a febrile illness that rapidly progressed to cardiopulmonary failure and the cause was not satisfactorily resolved. We describe the isolation and identification of a subgenus B adenovirus from the children who died.

METHODS

We studied two groups of children presenting to Sibu Hospital from April 14 to Sept 30, 1997. For children who died, the inclusion criterion was death after febrile illness, and for those who did not die it was acute flaccid paralysis (AFP). Serum and cerebrospinal fluid samples were tested for IgM antibodies to Japanese encephalitis and dengue viruses. Viruses isolated were identified by immunofluorescence, reverse-transcriptase PCR, or PCR and DNA sequencing.

FINDINGS

Enterovirus was isolated in three (19%) of 16 children who died and in none of the eight surviving children with AFP. However, an agent that was initially difficult to identify was found in ten (63%) children who died and five (63%) surviving children who had AFP. The agents isolated from ten (66.7%) of these 15 children were eventually identified as adenoviruses and were isolated mainly from clinically important sterile sites or tissues. All the enterovirus-positive children who died had this second agent.

INTERPRETATION

Our data raises doubts that EV71 was the only aetiological agent in these deaths.

Conformational considerations in the design of dual antagonists of platelet-activating factor (PAF) and histamine

Following the discovery of the first dual antagonist of platelet-activating factor (PAF) and histamine, 1-acetyl-4-(8-chloro-5,6-dihydro-11H-benzo[5,6]cyclohepta[1,2-b]pyridin- 11-ylidene)piperidine, Sch 37370, 1, a related series of structures, exemplified by (+/-)-1-acetyl-4-(8-chloro-5,6-dihydro-11H-benzo[5,6]-cyclohepta[1,2-b] pyridin-11-yl)piperazine, Sch 40338, 2, were prepared. Interestingly, the compounds exhibited a parallel structure antiallergy activity relationship, suggesting that the two series may adopt a common conformation at the PAF receptor. Conformational analysis led to a proposal for this bioactive conformation accessible to both series. The synthesis of novel conformationally constrained analogues that might mimic the proposed bioactive conformation of these compounds, and the evaluation of their in vitro antiallergy activity form the subject matter of this report.

Impaired membrane transport in methotrexate-resistant CCRF-CEM cells involves early translation termination and increased turnover of a mutant reduced folate carrier

The basis for impaired reduced folate carrier (RFC) activity in methotrexate-resistant CCRF-CEM (CEM/Mtx-1) cells was examined. Parental and CEM/Mtx-1 cells expressed identical levels of the 3. 1-kilobase RFC transcript. A approximately 85-kDa RFC protein was detected in parental cells by photoaffinity labeling and on Western blots with RFC-specific antiserum. In CEM/Mtx-1 cells, RFC protein was undetectable. By reverse transcriptase-polymerase chain reaction and sequence analysis, G to A point mutations were identified in CEM/Mtx-1 transcripts at positions 130 (P1; changes glycine 44 --> arginine) and 380 (P2; changes serine 127 --> asparagine). A 4-base pair (CATG) insertion detected at position 191 (in 19-30% of cDNA clones) resulted in a frameshift and early translation termination. Wild-type RFC was also detected (0-9% of clones). Wild-type RFC and double-mutated RFC (RFCP1+P2) cDNAs were transfected into transport-impaired K562 and Chinese hamster ovary cells. Although RFC transcripts paralleled wild-type protein, for the RFCP1+P2 transfectants, disproportionately low RFCP1+P2 protein was detected. This reflected an increased turnover of RFCP1+P2 over wild-type RFC. RFCP1+P2 did not restore methotrexate transport; however, uptake was partially restored by constructs with single mutations at the P1 or P2 loci. Cumulatively, our results show that loss of transport function in CEM/Mtx-1 cells results from complete loss of RFC protein due to early translation termination and increased turnover of a mutant RFC protein.

Cell surface expression of a human IgG Fc chimera activates macrophages through Fc receptors

Antibody-dependent cell-mediated cytotoxicity plays an important role in the macrophage-mediated destruction of target cells. While the selectivity is based on antibody specificity, the lytic attack is triggered by Fc receptor-mediated respiratory burst. To mimic IgG opsonization, a chimeric antibody-like molecule, containing human IgG1 Fc, was expressed on the surface of mammalian cells. The transmembrane domain of the human transferrin receptor was fused in-frame to the N-terminus of the second and third domains of human IgG1 heavy-chain constant region. This fusion molecule was designed to take advantage of the type II membrane anchor property of the transferrin receptor to express the Fc portion of the molecule in a reverse orientation, such that the Fc portion projected away from the cell surface. This is in contrast to the conventional cell surface IgG, which is anchored by a C-terminal type I transmembrane domain. The cell surface expressed reverse Fc no longer activated complement, but retained Fc receptor-binding capability and activated superoxide production by macrophages. This activity was completely blocked by an FcgammaR I-specific monoclonal antibody.

Evidence of cisplatin-induced senescent-like growth arrest in nasopharyngeal carcinoma cells

Cellular senescence is a programmed cell response leading to growth arrest in human diploid fibroblasts. We have shown that a nasopharyngeal carcinoma cell line, CNE1, following treatment by the DNA-damaging agent cisplatin, can undergo cellular senescent-like growth arrest, similar to fibroblasts, judged by cellular morphological changes and the expression of senescence-associated beta-galactosidase (SA-beta-gal). This senescent-like change was dose related; at 0.5 microgram/ml, the percentage of cisplatin-induced SA-beta-gal-positive cells was high (40-96%), and the staining was intense. Higher doses (1.0 and 2.0 micrograms/ml) of cisplatin induced lower SA-beta-gal expression (30-70%), and the process was irreversible. This cisplatin-induced cellular senescent-like response was not due to the inhibition of telomerase activity. Our results indicate that cellular senescent-like pathways exist in nasopharyngeal carcinoma cells and can be induced by cisplatin. Our evidence suggests that cellular senescent-like responses may be a cellular protection mechanism that acts differently in response to different degrees of cellular damage.

Structure and organization of the human reduced folate carrier gene

The human reduced folate carrier gene was found to contain 7 exons, including two alternative non-coding exons (exons 1 and 2), spanning approximately 29 kb. Two transcript variants involving exon 7 were detected in K562 cells by RT-PCR, distinguishable from the wild-type transcript by deletions of 625 bp (KS32) and 988 bp (KS1). The presence of consensus splice donor and acceptor elements in the deleted KS1 isoform suggested that this form was likely a splice variant; however, KS32 likely arose during reverse transcription rather than by alternative splicing.

Synthesis of a series of sulfinic acid analogs of GABA and evaluation of their GABAB receptor affinities

A series of gamma-aminobutyric acid (GABA) 1 analogs was prepared in which the carboxylic acid group of GABA was replaced with a sulfinic acid group and their affinity for the GABAB receptor investigated.

Expression profile of senescence-associated beta-galactosidase and activation of telomerase in human ovarian surface epithelial cells undergoing immortalization

Senescence is a specific physiological stage of cells characterized by long population doubling time. It accounts for the inability of normal somatic cells to undergo indefinite cell division. As the number of population doublings increase, cell cycle regulatory mechanisms come into play and signal cells to exit the cell cycle and become senescent. Senescence has been implicated in the aging process and may function as a tumor suppressor mechanism in human cells. The ability to measure the degree of cellular senescence is important in understanding the biological processes regulating cell aging and immortalization. Senescent cells exhibit an enzyme termed senescence-associated histochemical staining. Cells immortalized by viral oncogenes often enter a stage of crisis at the early phase of immortalization. The cells at crisis have a long population doubling time. Cells at the crisis stage resemble senescent cells and the expression of SA- beta-Gal may be used to monitor the process of immortalization. In this study the expression profile of SA-beta-Gal was examined in human ovarian surface epithelial cells (HOSE 6-3) undergoing immortalization by the human papilloma viral oncogene E6 and E7 (HPV E6 and E7). Our results showed a low percentage (12.0%) of HOSE 6-3 cells expressing SA-beta-Gal activity at the pre-crisis stage. The percentage of HOSE 6-3 cells expressing SA-beta-Gal activity was highest (39.2%) at the crisis stage. When HOSE 6-3 cells achieved immortalized status there was a sharp decrease in cells (1. 3%) expressing SA-beta-Gal activity. In addition, an inverse relationship between the expression of SA-beta-Gal activity and telomerase activity was noted in cells undergoing immortalization. The results confirm that the SA-beta-Gal enzyme is a good marker for monitoring the population of cells undergoing senescence at different stages of immortalization and that telomerase activation is a characteristic feature of post-crisis cells.

Effects of the loss of capacity for N-glycosylation on the transport activity and cellular localization of the human reduced folate carrier

The role of N-glycosylation in reduced folate carrier (RFC) transport and membrane targeting was examined in transport-deficient K562 (K500E) cells transfected with human RFC cDNAs. Treatment of cells expressing wild-type RFC with tunicamycin (0-3 microg) resulted in a progressive shift of the approximately 85 kDa RFC on western blots to 65 kDa. At 3 microg/ml tunicamycin, the nearly complete loss of glycosylated RFC was accompanied by a approximately 25% decreased rate of methotrexate uptake. A deglycosylated RFC cDNA construct in which asparagine-58 was replaced by glutamine (Gln58-RFC) was expressed in K500E cells as a 65 kDa protein and restored transport capacity for methotrexate and (6S)5-formyl tetrahydrofolate. With both wild-type and Gln58-RFC constructs, expression of cDNA-encoded RFC protein far exceeded relative levels of RFC uptake. Wild-type and Gln58-RFCs containing a hemagglutinin (HA) epitope at the carboxyl terminus were similarly functional and, by immunofluorescence staining with rhodamine-conjugated anti-HA antibody, were localized to plasma membranes. Collectively, our results demonstrate that N-glycosylation of human RFC plays no significant role in either transport function or membrane targeting. The discrepancy between the stoichiometries of RFC expression and transport activity for both wild-type RFC and Gln58-RFC implies that identical regulatory controls and/or non-RFC transport components are necessary to completely restore transport function in the transfected cells.

Reduced folate carrier gene expression in childhood acute lymphoblastic leukemia: relationship to immunophenotype and ploidy

Reduced folate carrier (RFC) transcripts in human leukemias were measured by a competitive PCR assay. Total RNAs were reverse transcribed and amplified in the presence of competitive templates for RFC and beta-actin. RFC transcripts were normalized to transcripts for beta-actin. In a series of K562 sublines, a approximately 30-fold range of RFC transcripts measured by PCR assay closely agreed with results of Northern analysis and varied in proportion to RFC protein on Western blots and [3H]methotrexate transport. RFC transcripts varied over a 88-fold range in 49 specimens from 48 children with acute lymphoblastic leukemia (ALL). Median RFC transcripts were similar for 15 T-cell and 33 B-precursor ALL samples (RFC/beta-actin = 6.13 x 10(-3) and 7.92 x 10(-3), respectively) and for 41 diagnostic (7.20 x 10(-3)) and 8 relapse (5.58 x 10(-3)) samples. Whereas PCR measurements of RFC transcripts approximated changes in methotrexate transport in B-precursor ALL blasts (n = 10), for T-ALL blasts (n = 12) there was no apparent relationship between these parameters. For hyperdiploid B-precursor blasts (n = 11) with greater than 52 chromosomes and three to five copies of chromosome 21, the median RFC transcript level was approximately 3-fold higher than that for diploid B-precursor blasts. RFC transcripts were also elevated for two of three B-precursor specimens with acquired trisomy 21. Our results suggest that RFC gene expression is far more predictive of methotrexate uptake capacity in B-precursor than T-ALL and that increased copies of chromosome 21 in B-precursor ALL blasts are generally associated with increased RFC transcripts. Hence, the good prognosis for children with hyperdiploid B-precursor ALL treated with antimetabolite-based chemotherapy and the high levels of methotrexate and methotrexate polyglutamates accumulated may, in part, reflect elevated RFC gene expression and capacities for methotrexate transport.

Induction of cyclooxygenase-2 and activation of nuclear factor-kappaB in myocardium of patients with congestive heart failure

BACKGROUND

Chronic heart failure is associated with induction of secondary inflammatory mediators, including prostanoids. The latter exert diverse functional and morphological effects on cardiac myocytes. Induction of cyclooxygenase (COX), the enzyme responsible for generating prostanoids, requires activation of nuclear factor-kappaB (NF-kappaB). The aim of the present study was to determine the expression of COX-2 and activation of NF-kappaB in the failing human heart.

METHODS AND RESULTS

Myocardial tissue from 27 patients with end-stage heart failure (various etiologies: ischemic heart disease, n=16; idiopathic dilated cardiomyopathy, n=10; and valvular heart disease, n=1), 2 septic patients, and 8 normal control subjects was immunostained with antisera to COX-2 and NF-kappaB. Western blotting was performed and showed high anti-COX-2 antibody specificity and the presence of COX-2 protein in the sample tissues. In situ hybridization and immunohistochemistry showed little or no expression of COX-2 and NF-kappaB in the control hearts. In contrast, there was abundant expression of COX-2 mRNA and protein in myocytes and inflammatory cells in areas of fibrotic scar compared with regions of normal morphology in all cases of heart failure, except the cases with sepsis, which showed an abundance of COX-2 throughout the myocardium. Sites of NF-kappaB activation were associated with those of COX-2 expression.

CONCLUSIONS

We demonstrate induction of COX-2 and activation of NF-kappaB in the myocardium of failing human hearts. Induction of both molecules appears to be associated with the presence of inflammation and scar formation.

Transcript heterogeneity of the human reduced folate carrier results from the use of multiple promoters and variable splicing of alternative upstream exons

We previously identified three separate cDNAs (KS6, KS32 and KS43) for the human reduced folate carrier (RFC) with unique 5' untranslated regions (5' UTRs) [Wong, Proefke, Bhushan and Matherly (1995) J. Biol. Chem. 270, 17468-17475]. Multiple RFC transcripts were confirmed in CCRF-CEM cells and transport-up-regulated K562.4CF cells by 5' rapid amplification of cDNA ends (5' RACE) and/or primer extension analysis. Two groups of 5' RACE clones were identified, one containing a variable length sequence identical with the KS43 cDNA 5' UTR, and another consisting of variants of the KS32 5' UTR, apparently generated by alternative splicing. The 5' UTR for the KS6 cDNA was not detected. A single band was detected on Southern blots of CCRF-CEM genomic DNA probed with a 326 bp genomic fragment common to all three cDNA species. The unique 5' UTRs for the KS43 and KS32 transcripts were localized to separate non-coding exons (exons 1 and 2 respectively), upstream from a large (approx. 3.42 kb) intron; the KS6 5'UTR also mapped to exon 1. Exons 1 and 2 were contiguous with 996 and 342 bp GC-rich 5' flanking regions (designated Pro43 and Pro32 respectively) that contained multiple SP1 and AP2 but no TATA or CAAT boxes. Both Pro43 and Pro32 exhibited strong promoter activities when cloned in front of a luciferase reporter gene and transfected into HT1080 and K562 cells. By an analysis of promoter deletion mutants we identified two 89 bp tandem repeats that seemed to increase Pro32 activity, and a 240 bp distal sequence that repressed Pro43 activity. Taken together, our results show that multiple human RFC transcripts are encoded by a single gene locus and that the heterogeneous 5' UTRs result from multiple transcriptional starts and variable splicing of alternative non-coding exons transcribed from separate promoters.

Gene amplification and increased expression of the reduced folate carrier in transport elevated K562 cells

The molecular bases for the 6-fold elevated methotrexate transport capacity of K562.4CF cells (Matherly et al., Cancer Res. 51: 3420-3426, 1991) were studied with reduced folate carrier (RFC) cDNA, genomic, and antibody probes. Southern analysis showed that RFC gene copies were increased (approximately 4- to 5-fold) in K562.4CF over wild-type K562 cells. Fluorescence in situ hybridization using a genomic RFC probe confirmed the localization of the RFC gene to the q-arm of chromosome 21. In K562.4CF cells, the frequent loss of a normal copy of chromosome 21 (61% of metaphases) was accompanied by RFC gene amplification and translocations of amplified RFC gene fragments to several (2 to 6) different chromosomal loci not seen in wild-type cells. Particularly intense RFC signals were mapped to homogeneously staining regions in chromosomes 2 and 15. Increased RFC gene copies were accompanied by a similar increase in the major 3.1 kb RFC transcript by northern blotting and an approximately 7-fold elevated level of the broadly migrating (80-95 kDa) RFC protein on a western blot probed with an RFC C-terminal peptide antibody. These results demonstrate that selection of cells with a growth-limiting concentration of reduced folates (0.4 nM of leucovorin) is sufficient to promote chromosomal aberrations, including gene amplification and translocations that result in increased RFC expression and folate transport.