Left ventricular end diastolic pressure for detection of intracoronary ergonovine-induced myocardial ischemia

BACKGROUND

Recent consensus on variant angina defines significant spasm as total or subtotal occlusion of a coronary artery. However, the clinical significance of "less-than-subtotal" spasm needs to be reappraised, especially if the coronary spasm is combined with chest pain. Therefore, we evaluated the feasibility of left ventricular end diastolic pressure (LVEDP) as a tool to detect myocardial ischemia during ergonovine provocation testing.

METHODS

After achieving two access sites, 29 patients underwent successful LVEDP monitoring using 5-Fr pigtail catheters during ergonovine provocation tests. Patients were divided into two groups based on the occurrence of anginal symptoms.

RESULTS

Of the 29 patients, 16 (55 %) patients had anginal symptoms. LVEDP was significantly increased in the symptomatic group compared with the nonsymptomatic group (∆LVEDP 5.6 ± 4.2 vs. 1.2 ± 2.0 mmHg, p = 0.002). However, of the 16 patients with anginal symptoms, positive provocation test results were confirmed in only six patients (38 %) as per the traditional standard (> 90 % inducible spasm of the epicardial coronary artery).

CONCLUSION

Compared with the traditional standard, LVEDP may have advantages in terms of elucidating anginal symptoms in patients suspected of having coronary vasospasm when performing ergonovine provocation tests.

Free-electron X-ray laser measurements of collisional-damped plasmons in isochorically heated warm dense matter

We present the first highly resolved measurements of the plasmon spectrum in an ultrafast heated solid. Multi-keV x-ray photons from the Linac Coherent Light Source have been focused to one micrometer diameter focal spots producing solid density aluminum plasmas with a known electron density of n_{e}=1.8×10^{23}  cm^{-3}. Detailed balance is observed through the intensity ratio of up- and down-shifted plasmons in x-ray forward scattering spectra measuring the electron temperature. The plasmon damping is treated by electron-ion collision models beyond the Born approximation to determine the electrical conductivity of warm dense aluminum.

Direct Observation of Melting in Shock-Compressed Bismuth With Femtosecond X-ray Diffraction

The melting of bismuth in response to shock compression has been studied using in situ femtosecond x-ray diffraction at an x-ray free electron laser. Both solid-solid and solid-liquid phase transitions are documented using changes in discrete diffraction peaks and the emergence of broad, liquid scattering upon release from shock pressures up to 14 GPa. The transformation from the solid state to the liquid is found to occur in less than 3 ns, very much faster than previously believed. These results are the first quantitative measurements of a liquid material obtained on shock release using x-ray diffraction, and provide an upper limit for the time scale of melting of bismuth under shock loading.

Association between information provision and decisional conflict in cancer patients

BACKGROUND

In this study, we aimed to identify demographic and clinical variables that correlate with perceived information provision among cancer patients and determine the association of information provision with decisional conflict (DC).

PATIENTS AND METHODS

We enrolled a total of 625 patients with cancer from two Korean hospitals in 2012. We used the European Organization for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire (QLQ-INFO26) to assess patients' perception of the information received from their doctors and the Decisional Conflict Scale (DCS) to assess DC. To identify predictive sociodemographic and clinical variables for adequate information provision, backward selective logistic regression analyses were conducted. In addition, adjusted multivariate logistic regression analyses were carried out to identify clinically meaningful differences of perceived level of information subscales associated with high DC.

RESULTS

More than half of patients with cancer showed insufficient satisfaction with medical information about disease (56%), treatment (73%), other services (83%), and global score (80%). In multiple logistic regression analyses, lower income and education, female, unmarried status, type of cancer with good prognosis, and early stage of treatment process were associated with patients' perception of inadequate information provision. In addition, Information about the medical tests with high DCS values clarity [adjusted odds ratio (aOR), 0.54; 95% confidence interval (CI) 0.30-0.97] and support (aOR, 0.53; 95% CI 0.33-0.85) showed negative significance. For inadequate information perception about treatments and other services, all 5 DCS scales (uncertainty, informed, values clarity, support, and effective decision) were negatively related. Global score of inadequate information provision also showed negative association with high DCS effective decision (aOR, 0.43; 95% CI 0.26-0.71) and DCS uncertainty (aOR, 0.46; 95% CI 0.27-0.77).

CONCLUSION

This study found that inadequate levels of perceived information correlated with several demographic and clinical characteristics. In addition, sufficient perceived information levels may be related to low levels of DC.

Long-term efficacy of biofeedback therapy in patients with dyssynergic defecation: results of a median 44 months follow-up

BACKGROUND

The beneficial effect of biofeedback therapy (BFT) over a period of more than 2 years has not been studied in a large group of patients. The aim of this study was to evaluate the long-term efficacy of BFT for dyssynergic defecation (DD).

METHODS

We evaluated the results for 347 consecutive constipated patients with DD who underwent BFT for a median of five sessions between 2004 and 2009. Initial responses were assessed immediately after the completion of BFT. A responder was defined as a subject with at least a three-point improvement from before to after BFT on an 11-point global bowel satisfaction (GBS) scale, or a two-point improvement if the baseline GBS was more than six points. The probability of remaining a responder was estimated by non-parametric maximum likelihood estimation.

KEY RESULTS

The initial response rate to BFT was 72.3% (n = 251), Parkinson's disease and higher baseline GBS scores were associated with initial non-response. The long-term efficacy of BFT was analyzed in 103 patients who were followed up for more than 6 months; the initial effects of BFT were maintained in 85 of the patients (82.5%) during a median of 44 months of follow-up (IQR = 12-68). The probability of remaining a responder was 60% at 2 years, and 58% at 5 years.

CONCLUSIONS & INFERENCES

The efficacy of BFT is maintained for more than 2 years after BFT in a considerable proportion of constipated patients with DD. BFT is effective and durable treatment for managing DD.

Further morphological observations on hearts with twisted atrioventricular connections (criss-cross hearts)

A superior and anterior location of the tricuspid valve in the setting of malalignment between the atrial and ventricular septal structures was the characteristic unifying morphologic feature of seven autopsied hearts with twisted atrioventricular connections. The peculiar angiocardiographic appearances of this lesion could be readily explained by the findings of unusual recesses in the right atrium, in the right ventricle, and in the left ventricle. The recess in the morphologically left ventricle was seen in each case at the right posterior part (or, in the hearts with left-handed ventricles, at the left part) of the chamber. Displacement of the right-sided atrioventricular valve far from the inferior caval vein (vena cava) had produced the recess in the morphologically right atrium; this feature was most prominent in the heart in which the atrioventricular connections were discordant. The recess within the right ventricular outflow tract was seen in four hearts, in all of which the inlet and apical trabecular components of the right ventricle were hypoplastic.

Shot-to-shot intensity and wavefront stability of high-harmonic generation

We report on the shot-to-shot stability of intensity and spatial phase of high-harmonic generation (HHG). The intensity stability is measured for each high-harmonic (HH) order with a spectrometer. Additionally, the spatial phase is measured with an XUV wavefront sensor for a single HH order measured in a single shot, which according to our knowledge was not reported before with a Hartmann wavefront sensor. Furthermore, we compare the single-shot measurement of the spatial phase with time-integrated measurements and we show that the XUV wavefront sensor is a useful tool to simultaneously optimize the spatial phase and intensity of HHG within the available HHG parameter range used in this study.

The ossification pattern in paediatric occipito-cervical spine: is it possible to estimate real age?

AIM

To retrospectively analyse the synchondrosis from the occipital bone to the whole cervical spine and determine the feasibility and validity of age estimation using computed tomography (CT) images.

MATERIAL AND METHODS

A total of 231 cervical spine or neck CT images of young children (<7 years of age) were examined. Twelve ossification centres were assessed (occiput: n = 2; atlas: n = 2; axis, n = 6; whole sub-axial vertebra: n = 2), and the ossification process was graded as open (O, fully lucent), osseous bridging (B, partially ossified), and fusion (F, totally ossified). After the first analysis was completed, the resulting chronological chart was used to estimate the age of 10 new cases in order to confirm the usefulness of the chart.

RESULTS

Infancy was easily estimated using the sub-axial or C2 posterior ossification centres, while the posterior occipital regions provided good estimation of age between 1-2 years. The most difficult period for accurate age estimation was between 2-4 years. However, the C2 anterior (neurocentral ossification) and C1 posterior regions did yield information to help determine the age around 3 years. The anterior occipital region was useful for age estimation between 4-5 years, and the C1-anterior region was potentially useful to help decide among the other parameters. The test for age estimation (TAE) had a very high ICC score (0.973) among the three observers.

CONCLUSION

Segmentalised analysis can enhance the ability to estimate real age, at least by the year. The analysis of the occipital bone made a strong contribution to the usefulness of the chorological chart. An organised chronological chart can provide readily available information for age estimation, and the primary application of the above data (TAE) demonstrated the validity of this approach.

Arachidonic acid promotes skin wound healing through induction of human MSC migration by MT3-MMP-mediated fibronectin degradation

Arachidonic acid (AA) is largely released during injury, but it has not been fully studied yet how AA modulates wound repair with stem cells. Therefore, we investigated skin wound-healing effect of AA-stimulated human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in vivo and its molecular mechanism in vitro. We found that transplantation of hUCB-MSCs pre-treated with AA enhanced wound filling, re-epithelization, and angiogenesis in a mouse skin excisional wound model. AA significantly promoted hUCB-MSCs migration after a 24 h incubation, which was inhibited by the knockdown of G-protein-coupled receptor 40 (GPR40). AA activated mammalian target of rapamycin complex 2 (mTORC2) and Akt^ser473 through the GPR40/phosphoinositide 3-kinase (PI3K) signaling, which was responsible for the stimulation of an atypical protein kinase C (PKC) isoform, PKCζ. Subsequently, AA stimulated phosphorylation of p38 MAPK and transcription factor Sp1, and induced membrane type 3-matrix metalloproteinase (MT3-MMP)-dependent fibronectin degradation in promoting hUCB-MSCs motility. Finally, the silencing of MT3-MMP in AA-stimulated hUCB-MSCs failed to promote the repair of skin wounds owing to impaired cell motility. In conclusion, AA enhances skin wound healing through induction of hUCB-MSCs motility by MT3-MMP-mediated fibronectin degradation, which relies on GPR40-dependent mTORC2 signaling pathways.

Comparison of computed tomographic findings in pulmonary mucormycosis and invasive pulmonary aspergillosis

Because there are no available molecular markers for pulmonary mucormycosis (PM), which has low culture sensitivity, early diagnosis and treatment rely heavily on imaging modes such as computed tomography (CT). However, there are limited data comparing CT findings for PM with those for invasive pulmonary aspergillosis (IPA). Adult patients who met the modified criteria for proven and probable PM (over an 11-year period) and IPA (over a 6-year period, owing to the availability of the galactomannan assay) according to the modified European Organization for Research and Treatment of Cancer/Mycosis Study Group definitions were retrospectively enrolled. IPA cases were selected at a 1 : 4 (PM/IPA) ratio. Thoracic CT scans were reviewed by two experienced radiologists blinded to the patients' demographics and clinical outcomes. A total of 24 patients with PM, including 20 (83%) with proven PM and four (17%) with probable PM, and 96 patients with IPA, including 12 (13%) with proven IPA and 84 (87%) with probable IPA, were eventually analysed. The reverse halo sign was more common in patients with PM (54%) than in those with IPA (6%, p < 0.001), whereas some airway-invasive features, such as clusters of centrilobular nodules, peribronchial consolidations, and bronchial wall thickening, were more common in patients with IPA (IPA 52% vs. PM 29%, p 0.04; IPA 49% vs. PM 21%, p 0.01; IPA 34% vs. PM 4%, p 0.003, respectively). The reverse halo sign was more common, and airway-invasive features were less common, in patients with PM than in those with IPA. These findings may help physicians to initiate Zygomycetes-active antifungal treatment earlier.

Investigation of femtosecond collisional ionization rates in a solid-density aluminium plasma

The rate at which atoms and ions within a plasma are further ionized by collisions with the free electrons is a fundamental parameter that dictates the dynamics of plasma systems at intermediate and high densities. While collision rates are well known experimentally in a few dilute systems, similar measurements for nonideal plasmas at densities approaching or exceeding those of solids remain elusive. Here we describe a spectroscopic method to study collision rates in solid-density aluminium plasmas created and diagnosed using the Linac Coherent light Source free-electron X-ray laser, tuned to specific interaction pathways around the absorption edges of ionic charge states. We estimate the rate of collisional ionization in solid-density aluminium plasmas at temperatures ~30 eV to be several times higher than that predicted by standard semiempirical models.

Blockade of CD40-CD154 costimulatory pathway promotes long-term survival of full-thickness porcine corneal grafts in nonhuman primates: clinically applicable xenocorneal transplantation

The porcine cornea may be a good solution for the shortage of human donor corneas because its size and refractive properties are comparable to those of the human cornea. However, antigenic differences need to be overcome to apply xenocorneal transplantation in actual clinical practice. We aimed to investigate the feasibility of full-thickness porcine corneas as human corneal substitutes using a CD40-CD154 costimulatory pathway blocking strategy in a clinically applicable pig-to-nonhuman primate corneal transplantation model. As a result, the mean survival time of the xenocorneal grafts in recipients who received anti-CD154 antibody-based immunosuppressants (POD318 (n = 4); >933, >243, 318 and >192) was significantly longer than that in controls (POD28 (n = 3); 21, 28 and 29; p = 0.010, log-rank test). Administration of anti-CD154 antibodies markedly reduced inflammatory cellular infiltrations (predominantly CD8 T cells and macrophages) into the xenocorneal grafts and almost completely blocked xenoantigen-triggered increases in Th1-associated cytokines, chemokines and C3a in the aqueous humor. Moreover, systemic expansion of memory T cells was effectively controlled and responses of anti-Gal/donor pig-specific antibodies were considerably diminished by programmed injection of anti-CD154 antibodies. Consequently, porcine corneas might be promising human corneal substitutes when the transplantation is accompanied by potent immunosuppression such as a CD40-CD154 costimulatory pathway blockade.

Spontaneous Zone III rupture of the flexor tendons of the ulnar three digits in elderly Korean farmers

Spontaneous flexor tendon rupture is a rare condition and the aetiology is not clear. We report 12 elderly Korean farmers with spontaneous flexor tendon ruptures. We found the rupture in the dominant hand in ten patients. A rupture in the little finger was found in all 12 patients (seven with both flexor tendons ruptured and five with only the profundus ruptured), in the ring finger in four patients (the profundus ruptured in all and both flexor tendons in two patients), and in the middle finger a partial rupture of the profundus in one patient. The tendons were ruptured close to the hook of the hamate. Repetitive friction between the flexor tendons and the hamate hook may cause the ruptures. The hamate hook was excised and the ruptured profundus tendons were reconstructed with tendon transfers with quite favourable functional recovery at follow-up of 1 to 2 years. The ruptured superficialis tendons were not reconstructed. Level of Evidence IV.

Telbivudine protects renal function in patients with chronic hepatitis B infection in conjunction with adefovir-based combination therapy

Previous studies have demonstrated that the treatment of chronic hepatitis B (CHB) infection with adefovir (ADV) can impair renal function. In contrast, treatment with telbivudine (LdT) improves renal function in CHB patients. The aim of this study was to evaluate the renoprotective effect of LdT in CHB patients receiving ADV-based combination therapy. The effects of treatment with ADV + LdT on renal function were compared to those resulting from treatment with ADV + entecavir (ETV), ADV + lamivudine (LAM), ADV alone and ETV alone. The consecutive cohort analysis included 831 CHB patients who received ADV + LdT, ADV + LAM, ADV + ETV, ADV alone or ETV alone for 96 weeks. Alterations in estimated glomerular filtration rate (eGFR) were compared between the five groups using a linear mixed-effects model. HBV DNA levels were also compared between the five groups during the 96-week period. Among the five treatment groups, significant improvements in eGFR were observed in the ADV + LdT and ADV + LAM groups over time (P < 0.001 for each group compared with baseline eGFR). In patients with a baseline eGFR between 50 and 90 mL/min, the change in eGFR was the most significant in the ADV + LdT group (+0.641 mL/min; P < 0.001). Age, gender, baseline eGFR and treatment option were significant predictive factors for eGFR changes. In conclusion, our results suggest that the combination therapy of LdT and ADV is significantly associated with renoprotective effects in CHB patients when compared with other ADV-based combination or single therapies.

Role of resistin in the inflammatory response induced by nicotine plus lipopolysaccharide in human periodontal ligament cells in vitro

BACKGROUND AND OBJECTIVE

Resistin was recently reported to play a role in inflammation-related diseases such as arthritis. However, the precise role of resistin in chronic inflammatory diseases, such as periodontal disease, remains unclear. The aim of this study was to investigate the combined effects of nicotine and lipopolysaccharide (LPS) on the expression of resistin and to assess whether resistin expression influences the levels of inflammatory cytokines, extracellular matrix (ECM) molecules and MMPs in human periodontal ligament cells (PDLCs) stimulated with both nicotine and LPS.

MATERIAL AND METHODS

PDLCs were pretreated with isoproterenol or resistin-specific small interfering RNA (siRNA), stimulated with LPS plus nicotine for 24 h, and then monitored for the production of inflammatory mediators. The concentrations of prostaglandin E2 (PGE2) and nitric oxide (NO) were measured by radioimmunoassay and the Griess method, respectively. RT-PCR and western blot analysis were used to measure the levels of mRNA and protein, respectively. Western blot analysis was also used to assess the activation of various signal-transduction pathways.

RESULTS

Treatment with nicotine plus LPS up-regulated the expression of resistin mRNA and the production of resistin protein in PDLCs in a time- and concentration-dependent manner. Isoproterenol-mediated interference with the function of resistin, or siRNA-mediated knockdown of resistin expression, markedly attenuated the LPS plus nicotine-mediated stimulation of PGE2 and NO production, the production of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase proteins and the expression of proinflammatory cytokines [tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-12] and MMPs (MMP-1, MMP-2 and MMP-9); however, these treatments restored the expression of ECM molecules. Furthermore, pretreatment with isoproterenol or resistin-specific siRNA blocked nicotine plus LPS-induced activation of phosphoinositide-3-kinase, glycogen synthase kinase-3 beta, β-catenin, p38, ERK, JNK and nuclear factor-κB.

CONCLUSION

This is the first study to show that the inhibition of resistin, by either a pharmacological or a genetic silencing approach, has anti-inflammatory effects. These effects include decreased levels of inflammatory cytokines and the prevention of ECM breakdown in a nicotine plus LPS-stimulated PDLC model.

New experimental platform to study high density laser-compressed matter

We have developed a new experimental platform at the Linac Coherent Light Source (LCLS) which combines simultaneous angularly and spectrally resolved x-ray scattering measurements. This technique offers a new insights on the structural and thermodynamic properties of warm dense matter. The < 50 fs temporal duration of the x-ray pulse provides near instantaneous snapshots of the dynamics of the compression. We present a proof of principle experiment for this platform to characterize a shock-compressed plastic foil. We observe the disappearance of the plastic semi-crystal structure and the formation of a compressed liquid ion-ion correlation peak. The plasma parameters of shock-compressed plastic can be measured as well, but requires an averaging over a few tens of shots.

Exploring Mbar shock conditions and isochorically heated aluminum at the Matter in Extreme Conditions end station of the Linac Coherent Light Source (invited)

Recent experiments performed at the Matter in Extreme Conditions end station of the Linac Coherent Light Source (LCLS) have demonstrated the first spectrally resolved measurements of plasmons from isochorically heated aluminum. The experiments have been performed using a seeded 8-keV x-ray laser beam as a pump and probe to both volumetrically heat and scatter x-rays from aluminum. Collective x-ray Thomson scattering spectra show a well-resolved plasmon feature that is down-shifted in energy by 19 eV. In addition, Mbar shock pressures from laser-compressed aluminum foils using velocity interferometer system for any reflector have been measured. The combination of experiments fully demonstrates the possibility to perform warm dense matter studies at the LCLS with unprecedented accuracy and precision.

Prognostic and predictive values of EGFR overexpression and EGFR copy number alteration in HER2-positive breast cancer

Background:

Epidermal growth factor receptor (EGFR) is overexpressed in a subset of human epidermal growth factor receptor 2 (HER2)-positive breast cancers, and coexpression of HER2 and EGFR has been reported to be associated with poor clinical outcome. Moreover, interaction between HER2 and EGFR has been suggested to be a possible basis for trastuzumab resistance.

Methods:

We analysed the clinical significance of EGFR overexpression and EGFR gene copy number alterations in 242 HER2-positive primary breast cancers. In addition, we examined the correlations between EGFR overexpression, trastuzumab response and clinical outcome in 447 primary, and 112 metastatic HER2-positive breast cancer patients treated by trastuzumab.

Results:

Of the 242 primary cases, the level of EGFR overexpression was 2+ in 12.7% and 3+ in 11.8%. High EGFR gene copy number was detected in 10.3%. Epidermal growth factor receptor overexpression was associated with hormone receptor negativity and high Ki-67 proliferation index. In survival analyses, EGFR overexpression, but not high EGFR copy number, was associated with poor disease-free survival in all patients, and in the subgroup not receiving adjuvant trastuzumab. In 447 HER2-positive primary breast cancer patients treated with adjuvant trastuzumab, EGFR overexpression was also an independent poor prognostic factor. However, EGFR overexpression was not associated with trastuzumab response, progression-free survival or overall survival in the metastatic setting.

Conclusions:

Epidermal growth factor receptor overexpression, but not high EGFR copy number, is a poor prognostic factor in HER2-positive primary breast cancer. Epidermal growth factor receptor overexpression is a predictive factor for trastuzumab response in HER2-positive primary breast cancer, but not in metastatic breast cancer.

Smoking cession decreases mean platelet volume in healthy Korean populations

BACKGROUND

Smoking is considered as a major modifiable risk factor for cardiovascular diseases. It has been shown that smoking cessation drops the risk of cardiovascular diseases such as myocardial infarction and also improves platelet function. Because mean platelet volume (MPV) is a simple and convenient indicator for platelet activation, we planned to investigate the effect of smoking status on MPV in healthy populations.

METHODS

This study was conducted on 398 individuals who visited our hospital for regular medical check-ups and were confirmed not to have diabetes or hypertension. MPV was measured using EDTA blood on an Advia 2120 (Siemens Healthcare Diagnostics Inc., Tarrytown, NY, USA) within 2 hours.

RESULTS

Present smokers showed higher MPV levels than present non-smokers. When MPV was compared by taking previous smoking history and present smoking status into account, the smoking cessation group showed significantly lower MPV levels than other groups.

CONCLUSIONS

Because this finding was significant only in the female group, the change in MPV according to smoking status was found to be different by gender. We carefully suggest that smoking cessation can lower the risk of cardiovascular diseases through the change in MPV, which can be more effective for women than men.

Absolute pulse energy measurements of soft x-rays at the Linac Coherent Light Source

This paper reports novel measurements of x-ray optical radiation on an absolute scale from the intense and ultra-short radiation generated in the soft x-ray regime of a free electron laser. We give a brief description of the detection principle for radiation measurements which was specifically adapted for this photon energy range. We present data characterizing the soft x-ray instrument at the Linac Coherent Light Source (LCLS) with respect to the radiant power output and transmission by using an absolute detector temporarily placed at the downstream end of the instrument. This provides an estimation of the reflectivity of all x-ray optical elements in the beamline and provides the absolute photon number per bandwidth per pulse. This parameter is important for many experiments that need to understand the trade-offs between high energy resolution and high flux, such as experiments focused on studying materials via resonant processes. Furthermore, the results are compared with the LCLS diagnostic gas detectors to test the limits of linearity, and observations are reported on radiation contamination from spontaneous undulator radiation and higher harmonic content.

Genotoxic stress/p53-induced DNAJB9 inhibits the pro-apoptotic function of p53

DNAJB9 is a recently isolated member of the molecular chaperone gene family, whose precise function is largely unknown. In the present study, we have identified DNAJB9 as an inducible gene of the tumor suppressor p53. DNAJB9 expression was induced by p53 or genotoxic stress in a p53-dependent manner, which was mediated by the Ras/Raf/ERK pathway. In addition, depletion of DNAJB9 by using siRNAs greatly increased genotoxic stress/p53-induced apoptosis, suggesting that DNAJB9 inhibits the pro-apoptotic function of p53. We also found that DNAJB9 physically interacts with p53 through its J domain, through which it inhibits the pro-apoptotic function of p53. Moreover, DNAJB9 colocalized with p53 in both cytoplasm and nucleus under genotoxic conditions. Together, these results demonstrate that DNAJB9 is a downstream target of p53 that belongs to the group of negative feedback regulators of p53.