EZH2 promotes neoplastic transformation through VAV interaction-dependent extranuclear mechanisms.

Recently, we reported that the histone methyltransferase, EZH2, controls leukocyte migration through interaction with the cytoskeleton remodeling effector, VAV, and direct methylation of the cytoskeletal regulatory protein, Talin. However, it is unclear whether this extranuclear, epigenetic-independent function of EZH2 has a profound impact on the initiation of cellular transformation and metastasis. Here, we show that EZH2 increases Talin1 methylation and cleavage, thereby enhancing adhesion turnover and promoting accelerated tumorigenesis. This transforming capacity is abolished by targeted disruption of EZH2 interaction with VAV. Furthermore, our studies demonstrate that EZH2 in the cytoplasm is closely associated with cancer stem cell properties, and that overexpression of EZH2, a mutant EZH2 lacking its nuclear localization signal (EZH2ΔNLS), or a methyl-mimicking Talin1 mutant substantially promotes JAK2-dependent STAT3 activation and cellular transformation. Taken together, our results suggest a critical role for the VAV interaction-dependent, extranuclear action of EZH2 in neoplastic transformation.

Dynamic change in natural killer cell type in the human ocular mucosa in situ as means of immune evasion by adenovirus infection.

The most severe form of virus-induced inflammation at the ocular surface is epidemic keratoconjunctivitis (EKC), often caused by group D human adenoviruses (HAdVs). We investigated the dynamics and mechanisms of changes in natural killer (NK) cell types in the human ocular mucosal surface in situ over the course of infection. In the acute phase of infection, the mature CD56(dim)NK cells that comprise a major subpopulation in the normal human conjunctiva are replaced by CD56(bright)NK cells recruited to the ocular surface by chemokines produced by the infected epithelium, and NKG2A-expressing CD56(dim) and CD56(bright) NK cells become the major subpopulations in severe inflammation. These NK cells attracted to the mucosal surface are however incapable of mounting a strong antiviral response because of upregulation of the inhibitory ligand human leukocyte antigen-E (HLA-E) on infected epithelium. Furthermore, group D HAdVs downregulate ligands for activating NK cell receptors, thus rendering even the mature NKG2A(-)NK cells unresponsive, an immune-escape mechanism distinct from other adenoviruses. Our findings imply that the EKC-causing group D HAdVs utilize these multiple pathways to inhibit antiviral NK cell responses in the initial stages of the infection.

The comparative accuracy of ultrasound and mammography in the detection of breast cancer.

AIM: This study was performed to determine the accuracy of ultrasound (USG) as compared to mammography (MMG) in detecting breast cancer. METHODS: This was a review of patients who had breast imaging and biopsy during an 18-month period. Details of patients who underwent breast biopsy were obtained from the department biopsy record books and imaging request forms. Details of breast imaging findings and histology of lesions biopsied were obtained from the hospital Integrated Radiology Information System (IRIS). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of USG and MMG were calculated with histology as the gold standard. RESULTS: A total of 326 breast lesions were biopsied. Histology results revealed the presence of 74 breast cancers and 252 benign lesions. USG had a sensitivity of 82%, specificity of 84%, PPV = 60%, NPV = 94% and an accuracy of 84%. MMG had a sensitivity of 49%, specificity of 89%, PPV = 53%, NPV = 88% and an accuracy of 81%. A total of 161 lesions which were imaged with both modalities were analyzed to determine the significance in the differences in sensitivity and specificity between USG and MMG. Sensitivity of USG (75%) was significantly higher than sensitivity of MMG (44%) (X(2)1=6.905, p=0.014). Specificity of MMG (91%) was significantly higher than specificity of USG (79%) (X(2)1=27.114, p<0.001). Compared with MMG, the sensitivity of USG was 50% (95% CI 10%-90%) higher in women aged less than 50 years (X(2)1=0.000, p=1.000) and 27% (95% CI 19%-36%) higher in women aged 50 years and above (X(2)1=5.866, p=0.015). Compared with MMG, the sensitivity of USG was 40% (95% CI 10%-70%) higher in women with dense breasts (X(2)1=0.234, p=0.628) and 27% (95% CI 9%-46%) higher in women with non-dense breasts (X(2)1=4.585, p=0.032). CONCLUSION: Accuracy of USG was higher compared with MMG. USG was more sensitive than MMG regardless of age group. However, MMG was more specific in those aged 50 years and older. USG was more sensitive and MMG was more specific regardless of breast density. In this study, 20% of breast cancers detected were occult on MMG and seen only on USG.

CLICK--topology-independent comparison of biomolecular 3D structures.

Our server, CLICK: http://mspc.bii.a-star.edu.sg/click, is capable of superimposing the 3D structures of any pair of biomolecules (proteins, DNA, RNA, etc.). The server makes use of the Cartesian coordinates of the molecules with the option of using other structural features such as secondary structure, solvent accessible surface area and residue depth to guide the alignment. CLICK first looks for cliques of points (3-7 residues) that are structurally similar in the pair of structures to be aligned. Using these local similarities, a one-to-one equivalence is charted between the residues of the two structures. A least square fit then superimposes the two structures. Our method is especially powerful in establishing protein relationships by detecting similarities in structural subdomains, domains and topological variants. CLICK has been extensively benchmarked and compared with other popular methods for protein and RNA structural alignments. In most cases, CLICK alignments were statistically significantly better in terms of structure overlap. The method also recognizes conformational changes that may have occurred in structural domains or subdomains in one structure with respect to the other. For this purpose, the server produces complementary alignments to maximize the extent of detectable similarity. Various examples showcase the utility of our web server.

Participation of nuclear factor (erythroid 2-related), factor 2 in ameliorating lithocholic acid-induced cholestatic liver injury in mice.

BACKGROUND AND PURPOSE: Lithocholic acid (LCA), the most toxic bile acid, induces cholestatic liver injury in rodents. We previously showed that LCA activates the oxidative stress-responsive nuclear factor (erythroid-2 like), factor 2 (Nrf2) in cultured liver cells, triggering adaptive responses that reduce cell injury. In this study, we determined whether Nrf2 protects the liver against LCA-induced toxicity in vivo. EXPERIMENTAL APPROACH: Nrf2 disrupted (Nrf2(-/-) ) and wild-type mice were treated with LCA (125 mg·kg(-1) body weight) to induce liver injury. Levels of mRNA, protein and function of important Nrf2 target genes coupled with liver histology and injury biomarkers of mice were examined. KEY RESULTS: In 4 day LCA treatments, we observed a significantly higher hepatic induction of Nrf2 target, cytoprotective genes including thioredoxin reductase 1, glutamate cysteine ligase subunits, glutathione S-transferases, haeme oxygenase-1 and multidrug resistance-associated proteins 3 and 4 in the wild type as compared with the Nrf2(-/-) mice. Moreover, basal and LCA-induced hepatic glutathione and activities of glutathione S-transferases and thioredoxin reductases were higher in wild-type than in Nrf2(-/-) mice. This reduced production of cytoprotective genes against LCA toxicity rendered Nrf2(-/-) mice more susceptible to severe liver damage with the presence of multifocal liver necrosis, inflamed bile ducts and elevation of lipid peroxidation and liver injury biomarkers, such as alanine aminotransferase and alkaline phosphatase. CONCLUSIONS AND IMPLICATIONS: Nrf2 plays a crucial cytoprotective role against LCA-induced liver injury by orchestrating adaptive responses. The pharmacological potential of targeting liver Nrf2 in the management of cholestatic liver diseases is proposed.

Hypertension in a residential home for the elderly in Penang, Malaysia.

A study of residents at the Silver Jubilee Home for the Aged was conducted to determine the prevalence, awareness and control of hypertension in this elderly community in Penang, Malaysia. Prevalence of hypertension was 36%, with 81% of patients being initially aware of this diagnosis. This relatively low hypertension prevalence rate may be because residents have a fairly sheltered lifestyle with less social stress and a daily routine that incorporates adequate exercise. Similarly, the high hypertension awareness rate compared to reported figures in the community may be because residents are more regularly monitored by the attending medical care-givers. At the beginning of the study, only 34% of hypertensive patients were well controlled with a blood pressure less than 140/90 mm Hg. This proportion rose to 53% at the end of study period. Compliance is better at a residential home because medication is served by their care-givers and cost is absorbed in this charitable organization. Our study suggests that hypertension awareness and control can be reasonable for the elderly in a residential home.

Audit of diagnostic and interventional craniocervical catheter angiographic procedures at the Singapore General Hospital.

INTRODUCTION: Catheter angiography is an established imaging modality of evaluating cerebral and head and neck vascular diseases. It is, however, an invasive procedure with a small risk of complications. The aim of our study was to evaluate the prevalence of peri-procedural complications in a local hospital setting. MATERIALS AND METHODS: A total of 88 patients underwent diagnostic and interventional craniocervical procedures over 6 months in our department. The casenotes of 83 patients were retrospectively reviewed for complications arising from a total of 99 procedures carried out. RESULTS: A new focal neurological deficit developed in 3 different patients after a procedure, giving a prevalence of 3.0%. All these occurred in diagnostic procedures and were permanent deficits with correlative computed tomography (CT) or magnetic resonance (MR) imaging findings of acute cerebral infarction. All these occurred in high-risk patients who had severe underlying cerebrocarotid vascular compromise. There was 1 case of contrast medium-induced nephropathy (1.0%), occurring in a patient with pre-existing renal impairment. Local complications included 1 case of iatrogenic external iliac artery dissection (1.0%) and 5 cases (5.1%) of small and uncomplicated puncture site groin haematomas. CONCLUSION: The most significant complication associated with a craniocervical angiographic procedure was the development of post-procedural stroke in patients with significant preexisting cerebrocarotid vascular compromise. In the absence of this risk factor, craniocervical catheter angiography is a relatively safe procedure.

Diffusion weighted MR imaging in acute stroke: the SGH experience.

Cerebrovascular accident (CVA) is a leading cause of death and disability in many countries. Diffusion-weighted (DW) magnetic resonance (MR) imaging has been reported to be useful in the detection of acute strokes and as an investigative tool evaluating the therapeutic effects of neuroprotective and thrombolytic agents. The objectives of this study are to share our experience using the commercially available isotropic DW scan in imaging of acute stroke, assess its usefulness over conventional T2-weighted (T2W) scans in a busy clinical radiology unit and highlight it pitfalls. We found the rapid sub-minute DW technique well suited for ill and restless stroke patients and superior to T2W scans in many ways. It was highly sensitive to acute ischaemic lesions, made lesions easily identifiable and readily differentiated the acute lesion from a background of multiple chronic infarcts. However, there are potential pitfalls in the evaluation of small hyperacute posterior fossa strokes and venous infarcts. The major strength of this MR technique lies in its ability to diagnose hyperacute strokes and thence the potential for therapeutic thrombolysis, but unfortunately patients qualifying for the "therapeutic window" were a minority. More efforts need to be focused on public education in order for this powerful imaging modality to find its true value and contribute to viability of an effective thrombolytic programme.

Correlation of the apparent diffusion coefficient and the creatine level in early ischemic stroke: a comparison of different patterns by magnetic resonance.

It has been reported that reduction of the apparent diffusion coefficient (ADC) after stroke can persist for several days, after which the ADC increases gradually to an abnormally high level. We evaluated ADC values of stroke lesions and compared the results to the cellular density of the lesion by means of the creatine (Cre) level. This two-parameter estimation is of particular relevance in ascertaining the underlying cellular status. Lesion-to-contralateral ADC ratios (ADCn) were obtained based on diffusion-weighted echo-planar and fast spin-echo imaging. Single-voxel localized spectroscopy was used for quantification of cerebral metabolites in infarcted regions. Their levels were also compared to that in homotopic contralateral regions. Fifteen patients with ischemic stroke were examined at times ranging from 18-88 hours following the onset of symptoms. In the stroke lesion, there was a significant correlation between the ADC and the Cre level showing that the higher the cell density the lower the ADC value. For ADCn vs. the lesion Cre concentration and the lesion-to-contralateral Cre ratio (Cre(n)), the strengths of relationship were R2 = 0.70 and 0.58, respectively. It is concluded that ADC is a good reflection of cell density. Greatly lowered ADC values occur within the context of a stable cellularity. ADC and the Cre level have complementary roles in the characterization of stroke lesion with regard to the sequential stage.

Chronic isolated vertigo.

Vertigo can be the first manifestation of vertebrobasilar ischaemia or brainstem and cerebellar stroke. Chronic isolated vertigo may pose a diagnostic dilemma. We report the case of a patient who presented with chronic isolated vertigo, and highlight the clinical use of magnetic resonance imaging and angiography in his management.

Spectrum of abnormal mammographic findings and their predictive value for malignancy in Singaporean women from a population screening trial.

INTRODUCTION: The ability to categorise mammographic features according to their likelihood of malignancy would be valuable in the management of women with abnormal mammograms. The aim of our study was to correlate abnormal mammographic features in a screened population with their histology to identify those features which are predictive of malignancy. The study also examined the spectrum of mammographic features in an Asian population. MATERIALS AND METHOD: This prospective study involved 28,231 women who were randomly selected from a population registry and underwent two-view screening mammography without physical examination. Women with suspicious lesions were recalled for further mammographic views or to a joint assessment clinic prior to biopsy. Mammographic abnormalities and their corresponding histology were assessed. RESULTS: The spectrum of mammographic abnormalities was similar to that in Caucasian populations. The positive predictive value for malignancy was 44.1% of all biopsied cases. Mammographic features could be broadly classified into low-, moderate- and high-risk categories for malignancy. Those features which correspond to high malignancy rates (9.8% to 16.0%) include multiple abnormalities or parenchymal lesions with microcalcifications. The presence of microcalcifications was a good predictor of ductal carcinoma-in-situ (DCIS): 46% of lesions in which the microcalcifications were the sole abnormality were DCIS only. Further, 71% of cancers with any microcalcification on the mammogram had a focus of DCIS on histology. CONCLUSION: Mammographic abnormalities can be segregated into three risk groups for malignancy, and this in turn can improve the selection criteria for breast biopsy, hence reducing unnecessary intervention. Furthermore, the presence of microcalcifications denotes the presence of DCIS, and would be an important determinant of the extent of surgical excision.

Ultrasonography and computed tomography in a clinical algorithm for the evaluation of suspected acute appendicitis in children.

AIM: To evaluate the roles and effectiveness of US and CT in a clinical algorithm for the evaluation of children with suspected appendicitis. METHODS: Patients with suspected appendicitis were prospectively evaluated with ultrasound (US), and in some cases with CT, after they were graded to have high, intermediate or low clinical likelihood for appendicitis. Imaging findings were made known to clinicians who then decided on a line of management. Patho-histological examination and clinical follow-up established the final diagnoses, which were correlated with the imaging findings. The effect of imaging on the management of patients was examined. RESULTS: Overall, the sensitivity of US was 92.9%, specificity 96.9%, accuracy 96.0%, positive predictive value 89.7% and negative predictive value 97.9%. Imaging did not affect the decision to operate in 13/14 (92.9%) patients in the high likelihood subgroup. Imaging guided the clinicians to the right management pathway in 26/30 (86.7%) patients in the intermediate group. 77/82 (93.9%) of US was truly negative in the low likelihood group. CT was performed in 12 patients because of unsatisfactory US scans or incompatibility between the US and the clinical findings. CT correctly diagnosed the presence or absence of appendicitis in all 12 patients. CONCLUSION: US and CT are accurate modalities in the diagnosis of acute appendicitis in children. US is most useful in patients with equivocal clinical findings. US should be the first modality used to evaluate children with suspected appendicitis. CT should be reserved for cases where US is sub-optimal or where the findings are inconsistent with the clinical findings.

Magnetic resonance imaging of brain metastases: magnetisation transfer or triple dose gadolinium?

Magnetic resonance (MR) imaging of brain metastases relies on the neovascularity of metastases and the associated breach of blood-brain barrier manifesting as enhancement on T1-weighted images. There are 2 main strategies to improve the detection of brain metastases. One may increase the dose of gadolinium and increase the signal of the lesion. Alternatively, one may also lower the signal of the background (by magnetisation transfer suppression), in which case the enhancing lesion is rendered more conspicuous without increasing the dose of gadolinium. We aim to compare the efficacy of single-dose conventional spin-echo T1 scans with magnetisation transfer (MT) suppression with triple-dose conventional spin-echo T1 scans in the detection of brain metastases in 18 patients undergoing imaging for brain metastases. An incremental dose technique was employed. After administration of a single dose of gadolinium, MT suppressed T1-weighted scans were obtained, followed by a conventional T1 scan. Two doses of gadolinium were subsequently given, achieving a cumulative triple-dose, and a conventional T1-weighted scan was then performed. We found single-dose MT suppressed and triple-dose scans performed equally well and detected 26 metastatic lesions. They detected 5 (5/26, 19%) more lesions than the conventional single-dose T1 scans. Five (5/21, 24%) questionable lesions on single-dose conventional scans were confidently diagnosed on the single-dose MT suppressed and the triple-dose conventional scan. We conclude that single-dose MT suppressed scans are a cost-effective technique of detecting brain metastases.

X-linked adrenoleukodystrophy: spinocerebellar variant.

The phenotypic variability in X-linked adrenoleukodystrophy (X-ALD) can be wide and varied. Rarely, it can present with clinical signs of spinocerebellar degeneration. There are very few reported cases of selective predominant white matter disease of the cerebellum in these patients. We report a patient with a rare variant of adult onset ALD who was previously diagnosed as spinocerebellar ataxia. He was a 24-year-old male who had delayed developmental milestones, developed signs of spinocerebellar degeneration (SCD) after 10 years of Addison's disease. Serial Magnetic Resonance Imaging (MRI), revealed cerebellar and pontine white matter disease but sparing the cerebral cortex and supratentorial white matter. His diagnosis of X-ALD was subsequently confirmed by the elevated serum very long chain fatty acids. This patient illustrates the unusual clinical presentation and imaging features of X-ALD and the importance of considering X-ALD in the clinical context of spinocerebellar degeneration. Early recognition of this rare variant would allow proper genetic counselling and institution of dietary therapy and/or bone marrow transplantation.

Role of magnetic resonance imaging and magnetic resonance angiography in patients with hemifacial spasm.

Vascular compression of the facial nerve is a well recognized cause of hemifacial spasm (HFS). In this study, we described the magnetic resonance imaging (MRI) and three-dimensional magnetic resonance angiography (MRA) techniques used and findings in 34 patients with hemifacial spasm. A vascular abnormality, defined as a vessel seen in close proximity, touching or compressing the facial nerve, was identified in 22 of the 25 patients (88%) who had both MRI and MRA studies. Vessels identified were anterior inferior cerebellar artery (59.2%), posterior inferior cerebellar artery (13.6%), vertebral artery (18.2%) and basilar artery (4.5%). All vascular abnormalities were ipsilateral to the side of the HFS. Only 3 of the 12 controls (25%) had a vascular abnormality in both MRI and MRA studies. One of the 9 HFS patients (11.1%) who had MRI only had an ipsilateral vascular abnormality. There is a role for combined MRI and MRA studies in the non-invasive evaluation of patients with HFS.

Portable chest radiography: comparison of high-resolution digital displays with laser printed digital film.

Computed radiology is a radiographic imaging technology that generates a conventional radiographic image in digital form. The image can be recorded on a laser sensitive film or archived to a digital storage device and displayed on a video monitor. This study was performed to evaluate the adequacy of reporting digitised images directly from the workstation. The test set consisted of portable chest images of 55 patients from the cardiothoracic intensive care unit. Normal structures and nine abnormalities were pre-selected for analysis. The radiographs and images on the video display were reviewed on two separate occasions, six months apart by two independent readers. No clinical details were supplied and the intraobserver and interobserver agreement were assessed using Kappa statistics. The overall results indicated that direct reporting from the workstation was as reliable as reporting from the laser printed copies.

Results of intermediate measures from a population-based, randomized trial of mammographic screening prevalence and detection of breast carcinoma among Asian women: the Singapore Breast Screening Project.

BACKGROUND: Although increasing rates of breast carcinoma incidence have been observed in Asian countries, appropriate strategies for detecting early stage breast carcinoma in such communities have been difficult to formulate, particularly because no large population screening trial specifically involving Asian women has been reported. The objective of this study was to evaluate the effectiveness and quality of mammography as a screening technique for Singaporean women, who are predominantly Chinese. METHODS: In this prospective study, 166,600 women in Singapore ages 50-64 years were randomized to either 2-view mammography without physical examination (67,656) or observation (97,294, controls) over 2 years. RESULTS: Of these women, 28,231 (41.7%) responded and were screened; they were more likely to be married, have more formal education, be working, be Chinese, and be in a higher socioeconomic group (P < 0.001 for all variables). To assess for response bias that could affect outcome, results were also evaluated for nonrespondents (n = 39,425). The incidence rate of cancers among nonrespondents (1 per 1000 woman-years) was less than the 1.3 in women not invited to have screening (P = 0.03, relative risk [RR], 1.3; 95% confidence interval [CI], 1.0-1.7). However, cancers arising from nonrespondents did not differ significantly in stage distribution when compared with cancers within the control group. For every 1000 women screened, 4.8 cancers were detected. The prevalence ratio (the number of cancers detected per 1000 women at first screening divided by the corresponding incidence rate in controls per year) was 3.6 for screened women and 2.4 for women invited to have screening. The majority of cancers detected through screening were early stage, with 64% as either ductal carcinoma in situ (26%) or Stage I disease (38%) and was significantly more than the corresponding 26% in women not invited to have screening (P < 0.001). When only invasive cancers were considered, screened women still had more early cancers, with 65% having no lymph node involvement, compared with 47% in the group not invited to have screening (P = 0.001; RR, 1.4; 95% CI, 1.2-1.7). Women who were screened had half the risk of having Stage II or later cancers (P < 0.0001; RR, 0.5; 95% CI, 0.4-0.7) when compared with women not invited to have screening. This higher detection rate of early cancers through screening was accomplished with acceptable recall rates of 8% for further mammographic films or physical examination and a biopsy rate of 1.0% (10 per 1000 women screened). The interval cancer rate was 2.1 per 10,000 women screened in the first year of follow-up. CONCLUSIONS: These positive results of intermediate measures suggest that, in Asian communities, screening mammography could be an important modality for detecting early stage breast carcinoma. However, the low compliance rates suggest that health education efforts must focus on issues related to acceptability if such programs are to succeed.

Reduction in retake rates and radiation dosage through computed radiography.

The availability of computed radiography has opened the possibility of using reduced dosage for radiographs in clinical settings and reducing the retake rate. A prospective controlled study was carried out over a period of four months comparing conventional X-rays and computed radiography. The aim was to assess if computed radiography at 50% normal dosage would result in films of adequate quality and a reduced retake rate compared to conventional radiography. The number and reason for retakes in each group were recorded. Film quality comparison using only chest X-rays (CXR) in one of three positions; erect posterior-anterior (PA), anterior-posterior (AP) sitting and supine was done by a panel of radiologists. A total of 6373 conventional and 4127 digital films were analysed. The overall retake rate was lower in the computed radiography group (4.6 vs 8.2% P < 0.001) as was the retake rate due to exposure factors (0.6% vs 3.2% P < 0.01). There was a higher proportion of optimal films in the computed radiography group for erect PA and sitting AP CXR (71% vs 61% P = 0.0015 and 64% vs 9% P = 0.0009 respectively) but no difference for supine films. Computed radiography resulted in a reduced retake rate due to exposure factors leading to a reduction in the overall retake rate. Despite 50% dosage reduction, films were of better or equal quality when compared to conventional radiography.

Radiological features in a patient with Kimura's disease.

Kimura's disease is an immune mediated inflammatory disorder that usually involves the head and neck region, primarily affecting the salivary glands, adjacent muscle and regional lymph nodes. Peripheral blood eosinophilia is the norm. Clinically and radiologically, it is difficult to differentiate Kimura's disease from salivary gland malignancy, lymphoma or haemangioma. The radiological findings of a patient who presented with a left facial mass involving the left parotid gland and the adjacent muscles are discussed. We also propose that the difference in the degree of enhancement between the initial and subsequent computed tomography study done two and a half years later may be due to the development of increased fibrosis and sclerosis as the disease progresses.