A nonsense mutation in zebrafish gata1 causes the bloodless phenotype in vlad tepes

Vlad tepes (vlt(m651)) is one of only five "bloodless" zebrafish mutants isolated through large-scale chemical mutagenesis screening. It is characterized by a severe reduction in blood cell progenitors and few or no blood cells at the onset of circulation. We now report characterization of the mutant phenotype and the identification of the gene mutated in vlt(m651). Embryos homozygous for the vlt(m651) mutation had normal expression of hematopoietic stem cell markers through 24 h postfertilization, as well as normal expression of myeloid and lymphoid markers. Analysis of erythroid development revealed variable expression of erythroid markers. Through positional and candidate gene cloning approaches we identified a nonsense mutation in the gata1 gene, 1015C --> T (Arg-339 --> Stop), in vlt(m651). The nonsense mutation was located C-terminal to the two zinc fingers and resulted in a truncated protein that was unable to bind DNA or mediate GATA-specific transactivation. A BAC clone containing the zebrafish gata1 gene was able to rescue the bloodless phenotype in vlt(m651). These results show that the vlt(m651) mutation is a previously uncharacterized gata1 allele in the zebrafish. The vlt(m651) mutation sheds new light on Gata1 structure and function in vivo, demonstrates that Gata1 plays an essential role in zebrafish hematopoiesis with significant conservation of function between mammals and zebrafish, and offers a powerful tool for future studies of the hematopoietic pathway.

Molecular cloning, genetic mapping, and expression analysis of four zebrafish c/ebp genes

The CCAAT/enhancer binding protein family (C/EBP) are transcription factors that play integral roles in the development and function of many organ systems, including hematopoietic cells, adipose tissues, and liver. We have identified and characterized putative zebrafish orthologs of mammalian C/EBP alpha, beta, gamma, and delta using low-stringency hybridization screening and computer searches of the GenBank EST database. c/ebpa and g were mapped within 1 cM of each other on linkage group (LG) 7, syntenic with human CEBPA and G genes on chromosome 19. c/ebpb was mapped to LG8, and c/ebpd was mapped to LG24, on the same LG as a recently identified unique c/ebp in zebrafish, c/ebp1. The mapping of these genes established new syntenic relationships between LG8 and human chromosome 20, extended existing synteny between LG7 and human chromosome 19, and confirmed the synteny between LG24 and human chromosome 8. In addition, these syntenies between zebrafish and human chromosomes are also conserved in the mouse genome. To characterize the expression of these genes, RNA in situ hybridization in embryos of wild type and a hematopoietic mutant, cloche, was performed. The results showed that zebrafish c/ebpa, b, g, and d were expressed in many embryonic tissues. c/ebpa and b were expressed in a subset of hematopoietic cells in a region consistent with myeloid expression. In addition, there was expression of c/ebpa and b in the liver and c/ebpa, b, and d in regions of the gastrointestinal tract. The expression of the c/ebps may serve as important markers for analysis of myelopoiesis, hepatic development, and other developmental processes in the future.

The role of continuous positive airway pressure in the treatment of congestive heart failure

Congestive heart failure (CHF) is a serious medical condition frequently associated with sleep-related breathing disorders, which remain underdiagnosed and undertreated. Recent studies have provided important insight into the pathophysiology of sleep apnea syndrome in patients with CHF, with potential therapeutic implications. In addition to abolition of sleep apnea, continuous positive airway pressure (CPAP) treatment can improve cardiac function and relieve symptoms of CHF. Postulated mechanisms include beneficial hemodynamic effects on ventricular remodeling, unloading of fatigued respiratory muscles, and neurohormonal modulation. Although medium-term studies using CPAP to treat sleep-related breathing disorders associated with CHF have been encouraging, more definitive data from ongoing large clinical trials are necessary to clarify its therapeutic role.

Effect of hyperoxia on left ventricular function and filling pressures in patients with and without congestive heart failure

STUDY OBJECTIVES

To determine the effects of hyperoxia on left ventricular (LV) function in humans with and without congestive heart failure (CHF).

DESIGN

An acute physiologic study of the effect of hyperoxia on right-heart hemodynamics, LV contractility (peak positive rate of rise of LV pressure [+dP/dt]), time constant of isovolumic left ventricular relaxation (tau), and LV filling pressures.

SETTING

Bayer Cardiovascular Clinical Research Laboratory at the Mount Sinai Hospital, Toronto, Ontario.

PATIENTS

Sixteen patients with stable CHF and 12 subjects with normal LV function received the hyperoxia intervention.

INTERVENTIONS

Patients received 21% O(2) by a nonrebreather mask, followed by 100% O(2) for 20 min, and 21% O(2) for a 10-min recovery period.

RESULTS

In response to hyperoxia, there was a 22 +/- 6% increase in LV end-diastolic pressure (LVEDP) in the CHF group and a similar 29 +/- 14% increase in LVEDP in the normal LV function group (p < 0.05 for both; mean +/- SEM). Hyperoxia was also associated with a prolongation in tau of 10 +/- 2% in the CHF group (p < 0.05) and 8 +/- 2% in the normal LV function group (p < 0.05). No changes in +dP/dt were observed in either group.

CONCLUSIONS

Hyperoxia was associated with impairment of cardiac relaxation and increased LV filling pressures in patients with and without CHF. These observations indicate that caution should be used in the administration of high inspired O(2) fractions to normoxic patients, especially in the setting of CHF.

Function of the inv(16) fusion gene CBFB-MYH11

Inv(16)(p13q22) is associated with acute myeloid leukemia subtype M4Eo, which is characterized by the presence of myelomonocytic blasts and atypical eosinophils. This chromosomal rearrangement results in the fusion of CBFB and MYH11 genes. Mouse models indicate that the fusion gene, Cbfb-MYH11, inhibits differentiation of hematopoietic cells. Although expression of Cbfb-MYH11 is not sufficient for leukemogenesis, a combination of Cbfb-MYH11 and additional mutations can lead specifically to the development of myeloid leukemia. Normally, CBFbeta interacts with CBFalpha to form a transcriptionally active nuclear complex. In vitro studies indicate that expression of CBFB-MYH11 leads to sequestration of CBFalpha2 in the cytoplasm. It also has been shown to inhibit CBF-mediated transactivation, slow cell cycle progression, delay the apoptotic response to DNA damaging agents, and protect CBFalpha2 from degradation. The importance of these functions in vivo remains to be determined.

Blood pressure cuff compression injury of the radial nerve

We describe a 19-year-old man who underwent emergency laparotomy for perforated peptic ulcer. He was otherwise healthy before this admission with no history of diabetes mellitus or neuropathy. A standard-size adult blood pressure cuff connected to a Dinamap monitor, set to cycle automatically every 3 minutes was affixed to his left upper extremity during surgery. One day after the operation he complained of numbness over the dorsum of the left hand and wrist drop. Physical examination revealed 0/5 muscle power of the left wrist and finger extensor muscles with reduced sensation on the radial aspect of the dorsum of the same hand. A diagnosis of acute radial nerve injury was made and rehabilitation was started. The wrist numbness and sensation improved with physical therapy, and he was discharged 9 days after the operation with an active wrist splint. He continued with rehabilitation on an out-patient basis. The muscle power of the wrist extensors gradually improved after three months of physical therapy and reverted to completely normal one month later. Locating the cuff higher on the arm, away from the elbow joint, to avoid the most superficial portion of radial nerve, may prevent this type of compression injury especially in asthenic patients.

A novel myeloid-restricted zebrafish CCAAT/enhancer-binding protein with a potent transcriptional activation domain

The CCAAT/enhancer-binding protein (C/EBP) family consists of transcription factors essential for hematopoiesis. The defining feature of the C/EBPs is a highly conserved carboxy-terminal bZIP domain that is necessary and sufficient for dimerization and DNA binding, whereas their amino-terminal domains are unique. This study reports a novel c/ebp gene (c/ebp1) from zebrafish that encodes a protein homologous to mammalian C/EBPs within the bZIP domain, but with an amino terminus lacking homology to any C/EBP or to any known sequence. In zebrafish embryos, c/ebp1 expression was initially observed in cells within the yolk sac circulation valley at approximately the 16-to 18-somite stage, and at 24 hours postfertilization (hpf), also in circulating cells. Most c/ebp1(+) cells also expressed a known early macrophage marker, leukocyte-specific plastin (l-plastin). Expression of both markers was lost in cloche, a mutant affecting hematopoiesis at the level of the hemangioblast. Expression of both markers was retained in m683 and spadetail, mutants affecting erythropoiesis, but not myelopoiesis. Further, c/ebp1 expression was lost in a mutant with defective myelopoiesis, but intact erythropoiesis. These data suggest that c/ebp1 is expressed exclusively in myeloid cells. In electrophoretic mobility shift assays, c/ebp1 was able to bind a C/EBP consensus DNA site. Further, a chimeric protein containing the amino-terminal domain of c/ebp1 fused to the DNA-binding domain of GAL4 induced a GAL4 reporter 4000-fold in NIH3T3 cells. These results suggest that c/ebp1 is a novel member of the C/EBP family that may function as a potent transcriptional activator in myeloid cells.

Left ventricular performance during prolonged exercise: absence of systolic dysfunction

We assessed left ventricular systolic and diastolic performance during and after prolonged exercise under controlled conditions in a group of healthy, trained men. Previous studies have examined the effects of prolonged effort on left ventricular function, yet it remains unclear whether or not left ventricular dysfunction (e.g. cardiac fatigue) can be produced under such conditions. We studied 15 healthy men, aged 27+/-1 years (mean+/-S.E.M.). Subjects exercised on bicycles at a constant work rate (60% of maximum oxygen uptake per min) for 150 min. Measurements of gas exchange, blood pressure and haematocrit were obtained, concurrent with the assessment of left ventricular function using equilibrium radionuclide angiography, at rest, during exercise (every 30 min) and after 30 min of recovery. Fluid replacement was provided and monitored during the exercise period. The baseline resting and exercise ejection fractions were 66+/-2% and 78+/-2% respectively. During exercise, subjects consumed 1816+/-136 ml of fluid, and the haematocrit had increased at 120 min of exercise (from 47.2%+/-0.6 to 49.9+/-0.8%; P<0.05). There was no change in either systolic or diastolic blood pressure throughout the exercise period, but heart rate drifted upwards from 141+/-2 beats/min after 30 min to 154+/-3 beats/min after 150 min (P<0.05). There was a small decline (8%; P<0.05) in end-diastolic volume at 150 min. No changes were observed in left ventricular ejection fraction, the pressure/volume ratio or end-systolic volume. After 30 min of sitting in recovery, heart rate was still higher than the pre-exercise value (84+/-3 compared with 69+/-2 beats/min; P<0.05), as were measures of peak filling rate and time to peak filling (P<0.05). The ejection fraction in the post-exercise recovery period was similar to the pre-exercise value. The results indicate that prolonged exercise of moderate duration may not induce abnormal left ventricular systolic function or cardiac fatigue during exercise.

Core-binding factor beta (CBFbeta), but not CBFbeta-smooth muscle myosin heavy chain, rescues definitive hematopoiesis in CBFbeta-deficient embryonic stem cells

Core-binding factor beta (CBFbeta) is the non-DNA-binding subunit of the heterodimeric CBFs. Genes encoding CBFbeta (CBFB), and one of the DNA-binding CBFalpha subunits, Runx1 (also known as CBFalpha2, AML1, and PEBP2alphaB), are required for normal hematopoiesis and are also frequent targets of chromosomal translocations in acute leukemias in humans. Homozygous disruption of either the Runx1 or Cbfb gene in mice results in embryonic lethality at midgestation due to hemorrhaging in the central nervous system, and severely impairs fetal liver hematopoiesis. Results of this study show that Cbfb-deficient mouse embryonic stem (ES) cells can differentiate into primitive erythroid colonies in vitro, but are impaired in their ability to produce definitive erythroid and myeloid colonies, mimicking the in vivo defect. Definitive hematopoiesis is restored by ectopic expression of full-length Cbfb transgenes, as well as by a transgene encoding only the heterodimerization domain of CBFbeta. In contrast, the CBFbeta-smooth muscle myosin heavy chain (SMMHC) fusion protein generated by the inv(16) associated with acute myeloid leukemias (M4Eo) cannot rescue definitive hematopoiesis by Cbfb-deficient ES cells. Sequences responsible for the inability of CBFbeta-SMMHC to rescue definitive hematopoiesis reside in the SMMHC portion of the fusion protein. Results also show that the CBFbeta-SMMHC fusion protein transdominantly inhibits definitive hematopoiesis, but not to the same extent as homozygous loss of Runx1 or Cbfb. CBFbeta-SMMHC preferentially inhibits the differentiation of myeloid lineage cells, while increasing the number of blastlike cells in culture.

Zebrafish homolog of the leukemia gene CBFB: its expression during embryogenesis and its relationship to scl and gata-1 in hematopoiesis

Mammalian CBFB encodes a transcription factor (CBF beta) that in combination with CBF alpha 2 binds to specific DNA sequences and regulates expression of a number of hematopoietic genes. CBFB is associated with human leukemias through a chromosome 16 inversion and is essential for definitive hematopoiesis during mouse embryo development. We have isolated a zebrafish cbfb complementary DNA (cDNA) clone from a zebrafish kidney cDNA library. This cbfb is highly homologous to human and mouse CBFB/Cbfb genes at both the DNA and protein level. In biochemical analyses, cbfbeta binds to human CBF alpha 2 and enhances its DNA binding. During zebrafish development, cbfb is expressed in the lateral plate mesoderm at tail bud stage and in the intermediate cell mass (ICM, the location of embryonic hematopoiesis) between the 21- to 26-somite stages. The cbfb is also expressed in Rohon-Beard cells, cranial nerve ganglia, hindbrain, retina, branchial arches, jaw, and fin buds. Expression of cbfb is decreased or absent in the ICM and Rohon-Beard cells in some hematopoietic mutants and is unaffected in others. We have also analyzed the expression of scl and gata-1 in the same hematopoietic mutants to ascertain the relative order of these transcription factors to cbfb in zebrafish hematopoiesis. Our results indicate that cbfb is expressed in early hematopoietic progenitors and that its expression pattern in the hematopoietic mutants is similar to that of scl. (Blood. 2000;96:4178-4184)

Effects of estrogen replacement on infarct size, cardiac remodeling, and the endothelin system after myocardial infarction in ovariectomized rats

BACKGROUND

Estrogen may increase the long-term survival of women who have suffered from a myocardial infarction (MI). We examined the acute and chronic influence of estrogen on MI in the rat left coronary artery ligation model.

METHODS AND RESULTS

Female Sprague-Dawley rats (10 to 12 weeks, n=93), divided into 3 groups (rats with intact ovaries, ovariectomized rats administered 17beta-estradiol [17beta-E(2)] replacement, and ovariectomized rats administered placebo 2 weeks before MI), were randomized to left coronary artery ligation (n=66) or sham-operated (n=27) groups. Ten to 11 weeks after MI, rats were randomly assigned to either (1) assessment of left ventricular (LV) function and morphometric analysis or (2) measurement of cardiopulmonary mRNA expression of preproendothelin-1 and endothelin A and B receptors. Acutely, estrogen was associated with a trend toward increased mortality. Infarct size was increased in the 17beta-E(2) group compared with the placebo group (42+/-2% versus 26+/-3%, respectively; P:=0.01). Chronically, wall tension was normalized through a reduction in LV cavity size with estrogen treatment (419+/-41 mm Hg/mm for 17beta-E(2) versus 946+/-300 mm Hg/mm for placebo, P:=0.039). In the LV, there was a 2.5-fold increase in endothelin B mRNA expression after MI in placebo-treated rats (P:=0.004 versus sham-operated rats) that was prevented in the 17beta-E(2) group (P:=NS versus sham-operated rats).

CONCLUSIONS

These results suggest that estrogen is detrimental at the time of MI or early post-MI period, resulting in an increased size of infarct or infarct expansion, but chronically, it can normalize wall tension and inhibit LV dilatation, which may in turn lead to increased long-term survival. Regulation of the endothelin system, particularly the expression of the endothelin B receptor, may contribute to these estrogenic effects.

Pulmonary valve replacement in adults late after repair of tetralogy of fallot: are we operating too late?

OBJECTIVES

The purpose of this study is to evaluate right ventricular (RV) volume and function after pulmonary valve replacement (PVR) and to address the issue of optimal surgical timing in these patients.

BACKGROUND

Chronic pulmonary regurgitation (PR) following repair of tetralogy of Fallot (TOF) leads to RV dilation and an increased incidence of sudden cardiac death in adult patients.

METHODS

We studied 25 consecutive adult patients who underwent PVR for significant PR late after repair of TOF. Radionuclide angiography was performed in all at a mean of 8.2 months (+/- 8 months) before PVR and repeated at a mean of 28.0 months (+/- 22.8 months) after the operation. Right ventricular (RV) end-systolic volume (RVESV), RV end-diastolic volume (RVEDV) and RV ejection fraction (RVEF) were measured.

RESULTS

Mean RVEDV, RVESV and RVEF remained unchanged after PVR (227.1 ml versus 214.9 ml, p = 0.74; 157.4 ml versus 155.4 ml, p = 0.94; 35.6% versus 34.7%, p = 0.78, respectively). Of the 10 patients with RVEF > or = 0.40 before PVR, 5 patients (50%) maintained a RVEF > or = 0.40 following PVR, whereas only 2 out of 15 patients (13%) with pre-operative values <0.40 reached an RVEF > or = 0.40 postoperatively (p < 0.001).

CONCLUSIONS

Right ventricular recovery following PVR for chronic significant pulmonary regurgitation after repair of TOF may be compromised in the adult population. In order to maintain adequate RV contractility, pulmonary valve implant in these patients should be considered before RV function deteriorates.

Function of CBFbeta/Bro proteins

Mammalian core binding factor beta (CBFbeta) and Drosophila Brother (Bro) and Big-brother (Bgb) proteins are transcription factors that dimerize with mammalian Runx and Drosophila Runt and Lozenge proteins and augment their DNA binding affinity and transcriptional potency. CBFbeta is essential for development and sustenance of definitive hematopoiesis during mouse embryogenesis. Bro and Bgb are required for Runt/Lozenge functions in Drosophila development. CBFbeta contributes to leukemogenesis since the CBFB gene is specifically and consistently mutated by a chromosome 16 inversion found in patients with acute myeloid leukemia subtype M4Eo. The ubiquitous expression pattern of the CBFB gene suggests that it may play important roles in many other organ systems.

Effects of continuous positive airway pressure on cardiovascular outcomes in heart failure patients with and without Cheyne-Stokes respiration

BACKGROUND

Continuous positive airway pressure (CPAP) improves cardiac function in patients with congestive heart failure (CHF) who also have Cheyne-Stokes respiration and central sleep apnea (CSR-CSA). However, the effects of CPAP in CHF patients without CSR-CSA have not been tested, and the long-term effects of this treatment on clinical cardiovascular outcomes are unknown.

METHODS AND RESULTS

We conducted a randomized, controlled trial in which 66 patients with CHF (29 with and 37 without CSR-CSA) were randomized to either a group that received CPAP nightly or to a control group. Change in left ventricular ejection fraction (LVEF) from baseline to 3 months and the combined mortality-cardiac transplantation rate over the median 2.2-year follow-up period were compared between the CPAP-treated and control groups. For the entire group of patients, CPAP had no significant effect on LVEF, but it was associated with a 60% relative risk reduction (95% confidence interval, 2% to 64%) in mortality-cardiac transplantation rate in patients who complied with CPAP therapy. Stratified analysis of patients with and without CSR-CSA revealed that those with CSR-CSA experienced both a significant improvement in LVEF at 3 months and a relative risk reduction of 81% (95% confidence interval, 26% to 95%) in the mortality-cardiac transplantation rate of those who used CPAP. CPAP had no significant effect on either of these outcomes in patients without CSR-CSA.

CONCLUSIONS

CPAP improves cardiac function in CHF patients with CSR-CSA but not in those without it. Although not definitive, our findings also suggest that CPAP can reduce the combined mortality-cardiac transplantation rate in those CHF patients with CSR-CSA who comply with therapy.

Isolation, genomic organization, and expression analysis of the mouse and rat homologs of MEFV, the gene for familial mediterranean fever

Familial Mediterranean fever (FMF) is a recessive disorder characterized by episodes of fever with serositis or synovitis. Recently the FMF gene (MEFV) was cloned; the protein product, pyrin/marenostrin, is thought to regulate inflammation in myeloid cells. In this manuscript we report the mouse and rat homologs of MEFV. The murine gene contains ten exons with a coding sequence of 2304 bp, while the rat homolog has nine exons with a coding sequence of 2253 bp. A considerable amino acid sequence homology was observed between the mouse and human (47.6% identity and 65.5% similarity) and between the mouse and rat genes (73.5% identity and 82.1% similarity). The predicted rodent proteins have several important domains and signals found in human pyrin, including a B-box zinc finger domain, Robbins-Dingwall nuclear localization signal, and coiled-coil domain. However, perhaps because of an ancient frame-shift mutation, neither the mouse nor the rat protein has an intact C-terminal B30.2 domain, in which most FMF-associated mutations have been found in human MEFV. Nevertheless, like the human gene, mouse Mefv is expressed in peripheral blood granulocytes but not lymphocytes. Consistent with its expression in granulocytes, Mefv was detected at high levels in the primary follicles and marginal zones of the splenic white pulp. Mefv is localized on mouse Chromosome (Chr) 16, region A3-B1, extending a region of synteny with human Chr 16p13.3. Development of knockout and knockin mouse models may provide further insights into the functional evolution of this gene.

Unsaturated aldehydes including 4-OH-nonenal are elevated in patients with congestive heart failure

BACKGROUND

Lipid peroxidation generates several unsaturated aldehydes, such as 4-OH-nonenal (HNE), which may interact with and modify the function of other molecules that are of biological importance. Although congestive heart failure (CHF) is a state of generalized oxidative stress, the resultant spectrum of saturated and unsaturated aldehydes has not been systematically characterized in this condition.

METHODS

We studied 8 CHF patients and 8 age-matched patients with normal left ventricular (LV) function. The concentrations of 22 aldehydes produced by lipid peroxidation, including saturated (n-alkanals) and unsaturated (t-2-alkenals, t-2,t-4-alkadienals, 4-OH-alkenals) aldehydes, were measured in arterial plasma by gas chromatography mass spectrometry (GC/MS). LV contractility (+dP/dt) and relaxation (Tau) were directly measured with a micromanometer-tipped catheter.

RESULTS

Compared with patients who have normal LV function, CHF patients had higher levels of total aldehydes (9,311 +/- 835 v 6,594 +/- 344 nmol/L, P < .01), as well as multiple unsaturated aldehydes (t-2-alkenals and 4-OH-alkenals, including HNE). In the CHF group, a strong relationship was observed between total aldehyde concentration and both +dP/dt (correlation coefficient = -0.76, P < .05) and Tau (correlation coefficient = 0.78, P < .05).

CONCLUSION

Unsaturated aldehyde levels were consistently elevated in the plasma of CHF patients compared with patients who have normal LV function. In CHF patients, elevated aldehyde levels were associated with impairment of LV contractility.

The coxsackie-adenovirus receptor (CAR) is used by reference strains and clinical isolates representing all six serotypes of coxsackievirus group B and by swine vesicular disease virus

Group B coxsackieviruses are etiologically linked to many human diseases, and cell surface receptors are postulated to play an important role in mediating their pathogenesis. The coxsackievirus adenovirus receptor (CAR) has been shown to function as a receptor for selected strains of coxsackievirus group B (CVB) serotypes 3, 4, and 5 and is postulated to serve as a receptor for all six serotypes. In this study, we demonstrate that CAR can serve as a receptor for laboratory reference strains and clinical isolates of all six CVB serotypes. Infection of CHO cells expressing human CAR results in a 1000-fold increase in CVB progeny virus titer compared to mock transfected cells. CAR was shown to be a functional receptor for swine vesicular disease virus (SVDV), as CHO-CAR cells but not CHO mock transfected controls were susceptible to SVDV infection, produced progeny SVDV, and developed cytopathic effects. Moreover, SVDV infection could be specifically blocked by monoclonal antibody to CAR (RmcB). SVDV infection of HeLa cells was also inhibited by an anti-CD55 MAb, suggesting that this virus, like some CVB, may interact with CD55 (decay accelerating factor) in addition to CAR. Finally, pretreatment of CVB or SVDV with soluble CAR effectively blocks virus infection of HeLa cell monolayers.

Repeated hypotensive episodes due to hepatic outflow obstruction during liver transplantation in adult patients

We report two cases of unusual repeated hypotension, decreased cardiac output, decreased mixed venous oxygen saturation, decreased central venous pressure, pulmonary artery pressure, and pulmonary wedge pressure after the completion of all vascular anastamoses of liver transplantation. These unstable hemodynamics appear to reflect a clinically relevant picture of hypovolemia. However, the real cause was partial hepatic outflow obstruction. The obstruction was suspected because hypotension was alleviated by elevating the full-sized liver graft ventrally and to the left. Doppler ultrasound examination confirmed that the flow velocity of the hepatic vein outflow was insufficient when the liver fell to its resting position in the right hepatic fossa. An additional side-to-side cavo-caval anastomosis resolved the problem in one patient, whereas the other required not only the additional anastomosis, but also application of a tissue expander filled with 770 mL normal saline beneath the liver to eliminate the obstruction. We emphasize that obstruction of the hepatic outflow causes only temporal hypovolemia because of a decrease of venous return and that treatment of this complication should be surgical intervention to relieve the obstruction. Blind resuscitation with fluids will not solve the problem and, in fact, may result in fluid overload with subsequent complications.

Cytotoxic aldehyde generation in heart following acute iron-loading

Although the mechanism of myocardial failure following acute iron poisoning is not known, excess iron-catalyzed free radical generation is conjectured to play a role. The effects of time (0 to 360 minutes) on total iron concentrations, glutathione peroxidase activity, and cytotoxic aldehyde production in heart of mice (B6D2F1, n = 65) were first investigated following acute iron-loading (20 mg iron dextran i.p./mouse). In a subsequent experiment, the effects of dose (0 to 80 mg iron dextran i.p./mouse, n = 75) on the aforementioned parameters were investigated. Our results show that the concentrations of cytotoxic aldehydes: (1) significantly differ over-time, with corresponding increases in total concentrations of iron (r = 0.93, p < 0.001); and (2) increase parallel to the total dose of iron administered (r = 0.95, p < 0.001). Furthermore, dose-and time-dependent alterations to glutathione peroxidase activity are observed, which is most likely due to an acute up-regulation of the enzyme as an endogenous protective response to increased free radical activity in the heart subsequent to iron-loading. While no single mechanism is likely to account for the complex pathophysiology of acute iron-induced heart failure, our results shown that iron-loading can result in significant free radical generation, as quantified by cytotoxic aldehydes, in heart tissue of mice. This is the first report on the effects of time and dose on cytotoxic aldehyde generation and glutathione peroxidase activity in heart of mice following acute iron-loading.

Effects of continuous positive airway pressure on cardiac volumes in patients with ischemic and dilated cardiomyopathy

The effects of continuous positive airway pressure (CPAP) on left (LV) and right ventricular (RV) volumes in patients with congestive heart failure (CHF) have not been studied. We hypothesized that CPAP would cause greater reductions in cardiac volumes in CHF patients with idiopathic dilated cardiomyopathy (IDC) than in those with ischemic cardiomyopathy (IsC), because their ventricles are more compliant. The effects of a 30-min CPAP application at 10 cm H(2)O on RV and LV end-diastolic (EDV) and end-systolic volumes (ESV), determined by radionuclide angiography, were therefore tested in 22 patients with CHF due to IsC (n = 13) or IDC (n = 9). CPAP-induced reductions in LVEDV, LVESV, RVEDV, and RVESV were significantly greater (p < 0.05) in the IDC than in the IsC group. Whereas in the IsC group CPAP caused no significant changes in LV or RV volumes, in the IDC group it induced significant reductions in RVEDV (527 +/- 77 ml to 354 +/- 50 ml, p = 0.03) and RVESV (400 +/- 78 ml to 272 +/- 54 ml, p = 0.04) that were greater than any reductions in LVEDV and LVESV. We conclude that CPAP causes greater short-term reductions in RV and LV volumes in CHF patients with IDC than in those with IsC, and that among patients with IDC, CPAP causes greater reductions in RV than in LV volumes.

Oxygen uptake kinetics during exercise in chronic heart failure: influence of peripheral vascular reserve

Exercise performance in chronic heart failure is severely impaired, due in part to a peripherally mediated limitation. In addition to impaired maximal exercise capacity, the O(2) uptake (VO(2)) response during submaximal exercise may be affected, with a greater reliance on anaerobiosis leading to early fatigue. However, the response of VO(2) kinetics to submaximal exercise in chronic heart failure has not been studied extensively; in particular, the relationship between oxygen utilization and the peripheral response to exercise has not been studied. The present investigation examined the time-constant (tau, corresponding to 63% of the total response fitted from exercise onset) of the VO(2) kinetics on-response to submaximal exercise and its relationship to maximal peripheral blood flow in patients with chronic heart failure, and compared responses with those in healthy sedentary subjects. Subjects were 10 patients with chronic heart failure (NYHA class II/III). The mean age was 50+/-12 years, with a mean resting left ventricular ejection fraction of 25+/-9%. Controls were 10 age-matched healthy subjects. VO(2(max)) was first determined for all subjects. Repeated transitions from rest to exercise were performed on a cycle ergometer while measuring breath-by-breath responses of VO(2) at a fixed work rate of 50% of VO(2(max)) (heart failure patients and healthy controls) and at a work rate equivalent to the average in heart failure patients (65 W; healthy controls only). On a separate occasion, post-maximal ischaemic exercise calf blood flow was measured (strain-gauge plethysmography). Whereas heart failure subjects displayed a significantly prolonged VO(2) kinetics response at a similar absolute workload (i.e. 65 W), as indicated by a longer tau value (42 s, compared with 22 s in controls; P<0.01), there was no difference in tau at a similar relative work rate [50% of VO(2(max))]. In addition, heart failure subjects demonstrated a lower maximal calf blood flow (P<0.05) than control subjects. These results indicate that patients with heart failure have a prolonged VO(2) kinetics on-response compared with healthy subjects at a similar absolute work rate (i.e. 65 W), but not at a similar relative work rate [50% of VO(2(max))]. Thus, despite a reduced maximal calf blood flow response associated with heart failure, it does not appear that this contributes to an impairment of the submaximal exercise response beyond that explained by a reduced maximal exercise capacity [VO(2(max))].

A biochemical, histochemical, and electron microscopic study on the effects of iron-loading on the hearts of mice

Acute iron poisoning and chronic iron overload are well-known causes of myocardial failure. Although the exact mechanism is not known, excess iron-catalyzed free radical generation is conjectured to play a role in damaging the myocardium and altering cardiac function. We report here on the effects of acute and chronic iron-loading on the total iron concentration, glutathione peroxidase activity, and cytotoxic aldehyde production in the heart of a murine model (n = 35). Light microscopic examination for the presence of ferrous and ferric iron was undertaken following histochemical staining for these species. In addition, examination of representative samples by transmission electron microscopy was performed. Our findings show that iron-loading can result in significant increases in total iron concentrations, alterations to glutathione peroxidase activity, and increases in cytotoxic aldehyde concentrations in the hearts of mice. Furthermore, we observe that iron-loading can significantly alter and damage various cellular constituents (e.g., mitochondria, lysosomes, sarcoplasmic reticulum) and this may have bearing on the mechanism of iron-induced heart failure.

The complete consensus sequence of coxsackievirus B6 and generation of infectious clones by long RT-PCR

The full length sequence for the human pathogen coxsackievirus B6 (CVB6, Schmitt strain) has been determined. We used long RT-PCR to generate full length DNA amplicon of CVB6, and then directly sequenced the amplicons. One-step cloning of the full length amplicon enabled us to obtain an infectious clone of CVB6. RNA generated from CVB6 amplicon DNA or CVB6 clones, by transcription with T7 RNA polymerase, was demonstrated to be infectious upon transfection into HeLa cells in vitro. The CVB6 genome is characteristic of enteroviruses, with a 5'-non-translated region (743 nucleotides) followed by an open reading frame (encoding a 2184 amino acid polyprotein) and a 3'-non-translated region (100 nucleotides) and polyadenylated tail. The predicted amino acid sequence of CVB6 clustered with the other CVB serotypes and swine vesicular disease virus (SVDV).

Cardiac function and cytotoxic aldehyde production in a murine model of chronic iron-overload

OBJECTIVES

To determine the relationship between the total chronic dose of iron administered, ex-vivo cardiac function and the concentrations of cytotoxic aldehydes in heart tissue of a murine model.

METHODS

In the first experiment, 34 male B6D2F1 mice were randomized to receive intraperitoneal injections of 5, 10 or 20 mg of iron dextran for three weeks, or a placebo control. The mice were subsequently randomized to undergo ex-vivo assessment of cardiac function. In the second experiment, free radical generation, quantified by the presence of 20 separate cytotoxic aldehydes, was assessed in heart tissue of 40 mice that were randomized to receive chronic treatment with various concentrations of iron dextran (100 mg to 300 mg total chronic dose administered), placebo treatment with saline, or no treatment at all (baseline).

RESULTS

Iron-loaded groups displayed dose-dependent depressions of heart rate, systolic pressure, developed pressure, coronary pressure, -dP/dt and +dP/dt, and increases in diastolic pressure. Monotonic dose-dependent increases in total heart aldehydes were observed in the iron-treated groups (r-0.97, p < 0.0001), whereas no significant differences were observed between baseline or time-placebo control groups.

CONCLUSIONS

While no single mechanism is likely to account for the complex pathophysiology of iron-induced heart failure, our findings show that chronic iron-loading in a murine model results in dose-dependent alterations to cardiac function; and results in free radical mediated damage to the heart, as measured by excess concentrations of cytotoxic aldehyde-derived peroxidation products. This is the first description of the effects of excess iron on cardiac function assessed by an ex-vivo Langendorff technique in a murine model of chronic iron-overload.

Potential role of the microvasculature in progression of heart failure

After cardiac injury, there are changes in the cardiac myocyte morphology, function, matrix, and molecular gene expression. These all play an important role in remodeling of the injured heart, contributing to the progression toward heart failure. The role of the microvasculature in the progression toward heart failure is less well characterized. However, laboratory studies have established that there are important interactions between the microvascular endothelium and the myocyte. Furthermore, in a multitude of animal models of heart failure and cardiomyopathy, there is always an association with microvascular abnormalities. Reversal of these abnormalities is also associated with improvement in the cardiomyopathy. Major mediators that likely play an important role in the microvasculature include endothelin and nitric oxide. These are elaborated by both endothelium and myocyte compartments of the myocardium. Preliminary clinical studies already demonstrate that microvascular ischemia may have prognostic power in patients with nonischemic dilated cardiomyopathy. Results from these studies showed a reduction in mortality from treatment with amlodipine, suggesting a possible benefit based on changes in the microvasculature.

Modulation of iron uptake in heart by L-type Ca2+ channel modifiers: possible implications in iron overload

Heart failure is the leading cause of mortality in patients with transfusional iron (Fe) overload in which myocardial iron uptake ensues via a transferrin-independent process. We examined the ability of L-type Ca2+ channel modifiers to alter Fe2+ uptake by isolated rat hearts and ventricular myocytes. Perfusion of rat hearts with 100 nmol/L 59Fe2+ and 5 mmol/L ascorbate resulted in specific 59Fe2+ uptake of 20.4+/-1.9 ng of Fe per gram dry wt. Abolishing myocardial electrical excitability with 20 mmol/L KCl reduced specific 59Fe2+ uptake by 60+/-7% (P<0.01), which suggested that a component of myocardial Fe2+ uptake depends on membrane voltage. Accordingly, 59Fe2+ uptake was inhibited by 10 micromol/L nifedipine (45+/-12%, P<0.02) and 100 micromol/L Cd2+ (86+/-3%; P<0. 001) while being augmented by 100 nmol/L Bay K 8644 (61+/-18%, P<0. 01) or 100 nmol/L isoproterenol (40+/-12%, P<0.05). By contrast, uptake of 100 nmol/L ferric iron (59Fe3+) was significantly lower (1. 4+/-0.3 ng Fe per gram dry wt; P<0.001) compared with divalent iron. These data suggest that a component of Fe2+ uptake into heart occurs via the L-type Ca2+ channel in myocytes. To investigate this further, the effects of Fe2+ on cardiac myocyte L-type Ca2+ currents were measured. In the absence of Ca2+, noninactivating nitrendipine-sensitive Fe2+ currents were recorded with 15 mmol/L [Fe2+]o. Low concentrations of Fe2+ enhanced Ca2+ current amplitude and slowed inactivation rates, which was consistent with Fe2+ entry into the cell, whereas higher Fe2+ levels caused dose-dependent decreases in peak current. Fe3+ had no effect on current amplitude or decay. Combined, our data suggest that myocardial Fe2+ uptake occurs via L-type Ca2+ channels and that blockade of these channels might be useful in the treatment of patients with excessive serum iron levels.

Relationship between K+ channel down-regulation and [Ca2+]i in rat ventricular myocytes following myocardial infarction

1. Cardiac hypertrophy and prolongation of the cardiac action potential are hallmark features of heart disease. We examined the molecular mechanisms and the functional consequences of this action potential prolongation on calcium handling in right ventricular myocytes obtained from rats 8 weeks following ligation of the left anterior descending coronary artery (post-myocardial infarction (MI) myocytes). 2. Compared with myocytes from sham-operated rats (sham myocytes), post-MI myocytes showed significant reductions in transient outward K+ current (Ito) density (sham 19.7 +/- 1.1 pA pF-1 versus post-MI 11.0 +/- 1.3 pA pF-1; means +/- s.e.m.), inward rectifier K+ current density (sham -13.7 +/- 0.6 pA pF-1 versus post-MI -10.3 +/- 0.9 pA pF-1) and resting membrane potential (sham -84.4 +/- 1.3 mV versus post-MI -74.1 +/- 2.6 mV). Depressed Ito amplitude correlated with significant reductions in Kv4.2 and Kv4.3 mRNA and Kv4.2 protein levels. Kv1.4 mRNA and protein levels were increased and coincided with the appearance of a slow component of recovery from inactivation for Ito. 3. In current-clamp recordings, post-MI myocytes showed a significant increase in [Ca2+]i transient amplitude compared with sham myocytes. Using voltage-clamp depolarizations, no intrinsic differences in Ca2+ handling by the sarcoplasmic reticulum or in L-type Ca2+ channel density (ICa,L) were detected between the groups. 4. Stimulation of post-MI myocytes with an action potential derived from a sham myocyte reduced the [Ca2+] transient amplitude to the sham level and vice versa. 5. The net Ca2+ influx per beat via ICa,L was increased about 2-fold in myocytes stimulated with post-MI action potentials compared with sham action potentials. 6. Our findings demonstrate that reductions in K+ channel expression in post-MI myocytes prolong action potential duration resulting in elevated Ca2+ influx and [Ca2+]i transients.

Central and peripheral adaptations after 12 weeks of exercise training in post-coronary artery bypass surgery patients

PURPOSE

Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients.

METHODS

Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined.

RESULTS

A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training.

CONCLUSIONS

These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.

Angiogenesis defects and mesenchymal apoptosis in mice lacking SMAD5

The transforming growth factor-beta (TGF-beta) signals are mediated by a family of at least nine SMAD proteins, of which SMAD5 is thought to relay signals of the bone morphogenetic protein (BMP) pathway. To investigate the role of SMAD5 during vertebrate development and tumorigenesis, we disrupted the Smad5 gene by homologous recombination. We showed that Smad5 was expressed predominantly in mesenchyme and somites during embryogenesis, and in many tissues of the adult. Mice homozygous for the mutation died between days 10.5 and 11.5 of gestation due to defects in angiogenesis. The mutant yolk sacs lacked normal vasculature and had irregularly distributed blood cells, although they contained hematopoietic precursors capable of erythroid differentiation. Smad5 mutant embryos had enlarged blood vessels surrounded by decreased numbers of vascular smooth muscle cells, suffered massive apoptosis of mesenchymal cells, and were unable to direct angiogenesis in vitro. These data suggest that SMAD5 may regulate endothelium-mesenchyme interactions during angiogenesis and that it is essential for mesenchymal survival.

Red light suppresses N-acetylserotonin but does not elevate 5-HT and 5-HIAA of the rat pineal glands at night

HPLC with EC detector was used to study the red light effect on the rhythmicity of catecholamines (NE, DOPAC and dopamine) and indoleamines (NAS, 5-HT, 5-HIAA) in the pineal glands and retinas of the Sprague-Dawley rat. We found the prominent nocturnal elevations of NAS in rat pineal glands and the suppression of the NAS but not the elevation of 5-HT and 5-HIAA after red light exposure at night. Our data show two findings: metabolic pathway of the indoleamines (5-HT, 5-HIAA and NAS) after red light exposure at night may be different from those by white light. Second, the increased HIOMT activity that effects on 5-HT and 5-HIAA may also be involved in the indoleamine formation after red light exposure at night.

Human artificial chromosomes generated by modification of a yeast artificial chromosome containing both human alpha satellite and single-copy DNA sequences

A human artificial chromosome (HAC) vector was constructed from a 1-Mb yeast artificial chromosome (YAC) that was selected based on its size from among several YACs identified by screening a randomly chosen subset of the Centre d'Etude du Polymorphisme Humain (CEPH) (Paris) YAC library with a degenerate alpha satellite probe. This YAC, which also included non-alpha satellite DNA, was modified to contain human telomeric DNA and a putative origin of replication from the human beta-globin locus. The resultant HAC vector was introduced into human cells by lipid-mediated DNA transfection, and HACs were identified that bound the active kinetochore protein CENP-E and were mitotically stable in the absence of selection for at least 100 generations. Microdissected HACs used as fluorescence in situ hybridization probes localized to the HAC itself and not to the arms of any endogenous human chromosomes, suggesting that the HAC was not formed by telomere fragmentation. Our ability to manipulate the HAC vector by recombinant genetic methods should allow us to further define the elements necessary for mammalian chromosome function.

Genomic acute myeloid leukemia-associated inv(16)(p13q22) breakpoints are tightly clustered

The inv(16) and related t(16;16) are found in 10% of all cases with de novo acute myeloid leukemia. In these rearrangements the core binding factor beta (CBFB) gene on 16q22 is fused to the smooth muscle myosin heavy chain gene (MYH11) on 16p13. To gain insight into the mechanisms causing the inv(16) we have analysed 24 genomic CBFB-MYH11 breakpoints. All breakpoints in CBFB are located in a 15-Kb intron. More than 50% of the sequenced 6.2 Kb of this intron consists of human repetitive elements. Twenty-one of the 24 breakpoints in MYH11 are located in a 370-bp intron. The remaining three breakpoints in MYH11 are located more upstream. The localization of three breakpoints adjacent to a V(D)J recombinase signal sequence in MYH11 suggests a V(D)J recombinase-mediated rearrangement in these cases. V(D)J recombinase-associated characteristics (small nucleotide deletions and insertions of random nucleotides) were detected in six other cases. CBFB and MYH11 duplications were detected in four of six cases tested.

CBFbeta-SMMHC, expressed in M4eo acute myeloid leukemia, reduces p53 induction and slows apoptosis in hematopoietic cells exposed to DNA-damaging agents

CBFbeta-SMMHC is expressed in M4Eo acute myeloid leukemia (AML) as a result of inv(16), but how it contributes to leukemogenesis is unknown. p53 mutations are rare in de novo AML, but they are common in many malignancies. Expression of CBFbeta-SMMHC in Ba/F3 cells reduced p53 induction in response to ionizing radiation or etoposide 3- to 4-fold. However, p53 induction was normal in Ba/F3 cells expressing a CBFbeta-SMMHC variant that does not interfere with DNA binding by CBF, indicating that a CBF genetic target regulates p53 induction. The p53 gene may be regulated by CBF, because p53 mRNA levels were reduced by CBFbeta-SMMHC. Reduced p53 induction was not caused by slowed cell proliferation, a consequence of CBFbeta-SMMHC expression, because p53 was induced similarly in control cultures and in cultures propagated in 10-fold less interleukin-3 (IL-3). CBFbeta-SMMHC did not slow apoptosis resulting from IL-3 withdrawal, where p53 induction is minimal, but slowed apoptosis in Ba/F3 cells exposed to 10 Gy of ionizing radiation or 3 to 8 microgram/mL etoposide, providing 2-fold protection at 6 or 18 hours. Inhibition of apoptosis was temporary, because all the cells exposed to these doses ultimately died, and clonal survival assays performed using 0. 04 microgram/mL etoposide did not show protection by CBFbeta-SMMHC. p21 levels were increased in cells subjected to DNA damage, regardless of CBFbeta-SMMHC expression and attenuated p53 induction. Bcl-2, bcl-xL, bcl-xS, and bax levels were unaffected by CBFbeta-SMMHC. Attenuated p53 induction may contribute to leukemogenesis by CBFbeta-SMMHC by slowing apoptosis via a p21-independent mechanism.

The leukemic protein core binding factor beta (CBFbeta)-smooth-muscle myosin heavy chain sequesters CBFalpha2 into cytoskeletal filaments and aggregates

The fusion gene CBFB-MYH11 is generated by the chromosome 16 inversion associated with acute myeloid leukemias. This gene encodes a chimeric protein involving the core binding factor beta (CBFbeta) and the smooth-muscle myosin heavy chain (SMMHC). Mouse model studies suggest that this chimeric protein CBFbeta-SMMHC dominantly suppresses the function of CBF, a heterodimeric transcription factor composed of DNA binding subunits (CBFalpha1 to 3) and a non-DNA binding subunit (CBFbeta). This dominant suppression results in the blockage of hematopoiesis in mice and presumably contributes to leukemogenesis. We used transient-transfection assays, in combination with immunofluorescence and green fluorescent protein-tagged proteins, to monitor subcellular localization of CBFbeta-SMMHC, CBFbeta, and CBFalpha2 (also known as AML1 or PEBP2alphaB). When expressed individually, CBFalpha2 was located in the nuclei of transfected cells, whereas CBFbeta was distributed throughout the cell. On the other hand, CBFbeta-SMMHC formed filament-like structures that colocalized with actin filaments. Upon cotransfection, CBFalpha2 was able to drive localization of CBFbeta into the nucleus in a dose-dependent manner. In contrast, CBFalpha2 colocalized with CBFbeta-SMMHC along the filaments instead of localizing to the nucleus. Deletion of the CBFalpha-interacting domain within CBFbeta-SMMHC abolished this CBFalpha2 sequestration, whereas truncation of the C-terminal-end SMMHC domain led to nuclear localization of CBFbeta-SMMHC when coexpressed with CBFalpha2. CBFalpha2 sequestration by CBFbeta-SMMHC was further confirmed in vivo in a knock-in mouse model. These observations suggest that CBFbeta-SMMHC plays a dominant negative role by sequestering CBFalpha2 into cytoskeletal filaments and aggregates, thereby disrupting CBFalpha2-mediated regulation of gene expression.

The core binding factor (CBF) alpha interaction domain and the smooth muscle myosin heavy chain (SMMHC) segment of CBFbeta-SMMHC are both required to slow cell proliferation

We have expressed several variants of core binding factor beta (CBFbeta)-smooth muscle myosin heavy chain (SMMHC) from the metallothionein promoter in Ba/F3 cells. Deletion of amino acids 2-11 from the CBFbeta segment, required for interaction with CBFalpha, prevented CBFbeta-SMMHC from inhibiting CBF DNA binding and cell cycle progression. Deletion of 283 carboxyl-terminal residues from the SMMHC domain, required for multimerization, also inactivated CBFbeta-SMMHC. Nuclear expression of CBFbeta(Delta2-11)-SMMHC was decreased relative to CBFbeta-SMMHC. CBFbeta(Delta2-11)-SMMHC linked to a nuclear localization signal still did not slow cell growth. The ability of each CBFbeta-SMMHC variant to inhibit CBF DNA binding and cell proliferation correlated with its ability to inhibit transactivation by an AML1-VP16 fusion protein. Thus, CBFbeta-SMMHC slows cell cycle progression from G1 to S phase by inhibiting CBF DNA binding and transactivation.

Construction of an approximately 700-kb transcript map around the familial Mediterranean fever locus on human chromosome 16p13.3

We used a combination of cDNA selection, exon amplification, and computational prediction from genomic sequence to isolate transcribed sequences from genomic DNA surrounding the familial Mediterranean fever (FMF) locus. Eighty-seven kb of genomic DNA around D16S3370, a marker showing a high degree of linkage disequilibrium with FMF, was sequenced to completion, and the sequence annotated. A transcript map reflecting the minimal number of genes encoded within the approximately 700 kb of genomic DNA surrounding the FMF locus was assembled. This map consists of 27 genes with discreet messages detectable on Northerns, in addition to three olfactory-receptor genes, a cluster of 18 tRNA genes, and two putative transcriptional units that have typical intron-exon splice junctions yet do not detect messages on Northerns. Four of the transcripts are identical to genes described previously, seven have been independently identified by the French FMF Consortium, and the others are novel. Six related zinc-finger genes, a cluster of tRNAs, and three olfactory receptors account for the majority of transcribed sequences isolated from a 315-kb FMF central region (between D16S468/D16S3070 and cosmid 377A12). Interspersed among them are several genes that may be important in inflammation. This transcript map not only has permitted the identification of the FMF gene (MEFV), but also has provided us an opportunity to probe the structural and functional features of this region of chromosome 16.