[Overexpression of NAT10 induced platinum drugs resistance in breast cancer cell].

Objective: To observe the platinum drugs resistance effect of N-acetyltransferase 10 (NAT10) overexpression in breast cancer cell line and elucidate the underlining mechanisms. Methods: The experiment was divided into wild-type (MCF-7 wild-type cells without any treatment) group, NAT10 overexpression group (H-NAT10 plasmid transfected into MCF-7 cells) and NAT10 knockdown group (SH-NAT10 plasmid transfected into MCF-7 cells). The invasion was detected by Transwell array, the interaction between NAT10 and PARP1 was detected by co-immunoprecipitation. The impact of NAT10 overexpression or knockdown on the acetylation level of PARP1 and its half-life was also determined. Immunostaining and IP array were used to detect the recruitment of DNA damage repair protein by acetylated PARP1. Flow cytometry was used to detect the cell apoptosis. Results: Transwell invasion assay showed that the number of cell invasion was 483.00±46.90 in the NAT10 overexpression group, 469.00±40.50 in the NAT10 knockdown group, and 445.00±35.50 in the MCF-7 wild-type cells, and the differences were not statistically significant (P>0.05). In the presence of 10 µmol/L oxaliplatin, the number of cell invasion was 502.00±45.60 in the NAT10 overexpression group and 105.00±20.50 in the NAT10 knockdown group, both statistically significant (P<0.05) compared with 219.00±31.50 in wild-type cells. In the presence of 10 µmol/L oxaliplatin, NAT10 overexpression enhanced the binding of PARP1 to NAT10 compared with wild-type cells, whereas the use of the NAT10 inhibitor Remodelin inhibited the mutual binding of the two. Overexpression of NAT10 induced PARP1 acetylation followed by increased PARP1 binding to XRCC1, and knockdown of NAT10 expression reduced PARP1 binding to XRCC1. Overexpression of NAT10 enhanced PARP1 binding to LIG3, while knockdown of NAT10 expression decreased PARP1 binding to LIG3. In 10 µmol/L oxaliplatin-treated cells, the γH2AX expression level was 0.38±0.02 in NAT10 overexpressing cells and 1.36±0.15 in NAT10 knockdown cells, both statistically significant (P<0.05) compared with 1.00±0.00 in wild-type cells. In 10 µmol/L oxaliplatin treated cells, the apoptosis rate was (6.54±0.68)% in the NAT10 overexpression group and (12.98±2.54)% in the NAT10 knockdown group, both of which were statistically significant (P<0.05) compared with (9.67±0.37)% in wild-type cells. Conclusion: NAT10 overexpression enhances the binding of NAT10 to PARP1 and promotes the acetylation of PARP1, which in turn prolongs the half-life of PARP1, thus enhancing PARP1 recruitment of DNA damage repair related proteins to the damage sites, promoting DNA damage repair and ultimately the survival of breast cancer cells.

Management of iatrogenic porto-biliary fistula following biliary stent.

We describe a case of cystic pancreatic disease causing biliary obstruction requiring percutaneous biliary stenting. The patient subsequently re-presented with severe melaena shown to be due to a rare complication of biliary stenting with development of a porto-biliary fistula from stent erosion, successfully managed with a 'stent-within-stent'.

Typical magnetic resonance features of a haemangioblastoma, an uncommon nerve root lesion: case report and literature review.

Haemangioblastomas are uncommon tumours of the central nervous system. Nerve root haemangioblastomas with both intradural and extradural components are extremely rare. We present a case of a C2 nerve root haemangioblastoma in a 64-year-old man where the preoperative diagnosis was a spinal meningioma. An unexpectedly vascular tumour was found at initial procedure. Urgent catheter angiography was performed and the tumour was embolized prior to complete excision at a subsequent procedure.

Exchanging dual-lumen central venous catheters: how I do it.

The management of a blocked long-term central venous catheter has traditionally been removal and re-siting, even when device failure is not associated with venous thrombosis or sepsis. It is not possible to 'railroad' a split dual-lumen central venous catheter down a long tortuous s.c. tunnel. Our exchange technique was designed to salvage the tunnel and venous access site in a long-term catheter that has had uncomplicated primary device failure. In this technique we divide the dual-lumen catheter and secure the venous access site and the s.c. tunnel with separate peel-away sheaths. The new catheter is then introduced in the conventional manner through the two peel-away sheaths, which are then removed. The key advantage of the technique is that it preserves one of the few central venous access sites available. This article describes exchange of an internal jugular catheter, but the same technique is applicable to subclavian catheters.

Survey on mammographic screening among women aged 40 to 65 years old at polyclinics.

INTRODUCTION: Breast cancer is the commonest female cancer in Singapore. It is steadily rising with an incidence of 53.1 cases per 100,000 persons per year among women. Screening for detection of early lesions which are highly curable helps to reduce mortality. METHODS: Over three afternoon sessions in December 2003, 224 female patients aged 40-65 years, participated in interviews conducted by the National Healthcare Group Polyclinics, Singapore. The survey sought information on mammographic screening history, the time interval since the previous mammographic screening, and the reasons for not going for the screening. RESULTS: The survey found that only 26.4 percent (28 out of 106) among those aged 40 to 49 years had mammographic screening done within the past one year, and 43.2 percent (51 out of 118) among those aged 50 to 65 years had screening done within the last two years. Chinese women were twice more likely than Malay women to have a mammogram done. The commonest reasons for not wanting to have mammographic screening among women who did not have a mammogram done or had mammogram done more than two years ago, were lack of time (42.5 percent), fear of pain during the procedure (26.9 percent), and the belief that cancer would not happen to them (24.6 percent). CONCLUSION: Despite publicity on breast cancer being the commonest cancer among women in Singapore and cure being possible if the malignancy was detected early, close to half of the women aged 40-65 years old who attended the National Healthcare Group Polyclinics did not have mammographic screening done. One-quarter of the women who did not have mammogram screening did not do so as they did not think cancer would happen to them.

Use of intra-arterial multi-detector row CT angiography for the evaluation of an ischaemic limb in a patient with renal impairment.

The vastly improved scanning speed and z-axis resolution afforded by multi-detector technology has allowed CT to refine its traditional roles and to explore many new applications in imaging. We present a case report of a patient with renal failure and an ischaemic leg, which illustrates a useful new CT vascular imaging application. By carrying out 16-channel multi-detector row CT angiography through a sheath introduced into the common femoral artery, we obtained a high-quality angiographic image of the affected leg, using only 30 mL of iodinated contrast material. The examination definitively showed the number, distribution and patency of the tibial run-off arteries, with significant influence on the patient's subsequent clinical management. This simple and relatively minimally invasive technique is useful in peripheral vascular imaging, when conventional CT angiography using a large volume of i.v. contrast and MR angiography are unsuitable or unavailable.

Managing peripherally inserted central catheter-related venous thrombosis: How I do it.

Imaging-guided insertion of central venous catheters, either in the form of a peripherally inserted central catheter (PICC) or through a subclavian or a jugular approach, is becoming the preferred method of acquiring long-term venous access for a variety of therapeutic purposes. The most significant complication from central venous catheters is thrombosis of the catheterized vein. Venous thrombosis related to the insertion of PICC lines is conventionally treated with line removal followed by anticoagulation. Direct thrombolysis with urokinase, using the lumen of the PICC line to facilitate the insertion of the infusion catheter is a simple, safe and effective treatment option. In this article, we describe our experience with this procedure and the technique used.

Interpreting urgent brain CT scans: Does review by a radiology trainee make a difference in accuracy?

An urgent brain CT scan is now commonly performed on patients presenting to hospital emergency departments for a wide variety of indications. At most institutions in Australia, such scans are reviewed immediately by an on-call radiologist, who is usually an accredited registrar. The value of the trainee radiologist in such a setting is unclear. In the present study, the rate of abnormal findings in a random sample of 100 brain CT scans performed on hospital patients is reviewed and the accuracy of detection of potentially urgent lesions is compared between three junior clinicians, an accredited radiology registrar and a junior radiographer, using the final radiological report as the standard of reference. At least one potentially urgent abnormality in 25% of the patients scanned was found. The RANZCR trainee recorded a significantly higher sensitivity compared to the other readers. It is concluded that an urgent brain CT is of greater value as a screening test if a contemporaneous radiological review is made available, and the implications this may have on current imaging practices are briefly considered.

The field testing of Denver Developmental Screening Test Singapore: a Singapore version of Denver II Developmental Screening Test.

The Denver Developmental Screening Test, Singapore (DDST, Singapore), a Singapore version of the Denver II Developmental Screening Test, was field-tested, using trained staff nurses as testers, on 2459 children (known cases excluded), in 5 key ages of 3 months, 9 months, 17 months, 37 months and 60 months. Only 2.6% (65) of the parents suspected developmental problems in their children before screening. Taking children with "questionable" (7.2%), "abnormal" (3.7%) and "untestable" (1.7%) scores as the screened-out cases, the DDST, Singapore had a screened-out rate of 12.6%. A total of 171 screened-out cases and 168 "normal" children were also evaluated by the Development Assessment Clinic (DAC) of the Singapore General Hospital and the results were compared in these 2 groups of children. Among the screened-out cases, 16.6% were confirmed or suspected to have neuro-developmental disorders (NDDs) by the DAC. The computed NDD rate in the study sample was 5.3%. Based on a single DDST, Singapore test result, there was a high false positive rate of 83.5% and lower false negative rate of 3.7% compared to the DAC assessment. However, the high false positive rate would be significantly reduced by doing a repeat screening test on the "questionable" cases and having the screened-out cases assessed by trained primary health care doctors. In conclusion, no major revision is needed in the scoring criteria suggested in the current version of DDST, Singapore. It is a useful tool in identifying children who will otherwise be missed without formal screening.

Reduction of inflammation and pyrexia in the rat by oral administration of SDZ 224-015, an inhibitor of the interleukin-1 beta converting enzyme.

1. The aim of this study was to determine whether a synthetic inhibitor of the interleukin-1 beta converting enzyme (ICE) displays oral activity in models of inflammation. 2. To this end, the ICE inhibitor, SDZ 224-015, was examined in rat paw oedema, pyrexia and nociception tests. 3. SDZ 224-015 (0.3-300 micrograms kg-1) potently reduced carrageenin-induced paw oedema, with an oral ED50 of approximately 25 micrograms kg-1. This effect was independent of endogenous glucocorticoid, as shown by retention of activity upon adrenalectomy. 4. Pyrexia induced by lipopolysaccharide (0.1 mg kg-1 s.c.) or by interleukin-1 beta (100 ng i.v.) was also reduced, over a similar dose-range to oedema (oral ED50s 11 micrograms kg-1 and 4 micrograms kg-1 respectively). 5. SDZ 224-015 (0.2-5 mg kg-1, p.o.) displayed analgesic activity in the Randall-Selitto yeast-inflamed paw pressure test, significant at a dose of 1 mg kg-1, p.o. 6. Thus, SDZ 224-015 has potent oral activity in several acute models for inflammation, suggesting that ICE inhibitors may constitute a novel type of anti-inflammatory agent.

Expression, refolding, and autocatalytic proteolytic processing of the interleukin-1 beta-converting enzyme precursor.

The interleukin-1 beta-converting enzyme is a heterodimeric cysteine protease that is produced as a 45-kDa precursor. The full-length precursor form of the enzyme was expressed in Escherichia coli as insoluble inclusion bodies. Following solubilization and refolding of the 45-kDa protein, autoproteolytic conversion to a heterodimeric form containing 10- and 20-kDa subunits was observed. This enzyme had catalytic activity against both natural (interleukin-1 beta precursor) and synthetic peptide substrates. The inclusion of a specific inhibitor (SDZ 223-941) of the converting enzyme in the refolding mixture prevented proteolytic processing to the 10-/20-kDa form. Similarly, refolding under nonreducing conditions also prevented processing. Time course experiments showed that the 10-kDa subunit was released from the 45-kDa precursor before the 20-kDa subunit, implying that the N-terminal portion of the precursor is released last and may play a regulatory role.