Focusing subwavelength grating coupler for mid-infrared suspended membrane waveguide

A mid-infrared (mid-IR)-focusing subwavelength grating (SWG) coupler and suspended membrane waveguide (SMW) on a silicon-on-insulator wafer are studied. For a transverse-electric mode uniform SWG, finite-difference time-domain simulation predicts 44.2% coupling efficiency with 1 dB bandwidth of about 220 nm and backreflection of 0.78% at 2.75 μm. Then the uniform SWG is curved to a focusing SWG using a phase-matching formula. The SMWs are analyzed by the finite element method and fabricated. An Er3+-Pr3+ co-doped mid-IR fiber laser is used for device characterization. The fabricated mid-IR SWG coupler has 24.7% coupling efficiency.

Dural tear post mastoidectomy repaired with Dura Gen

Dural exposure may occur during the course of thinning the tegmen tympani and tegmen mastoideum in mastoid procedure. If large area of dura is exposed or lacerated, cerebrospinal fluid and brain herniation may enter the mastoid cavity. We report a case of a patient with injured dura mater and tegmen mastoideum during mastoidectomy for chronic suppurative otitis media with cholesteatoma managed by using DuraGen. The dura mater and tegmen defect healed totally showing the success of the procedure. A collagen matrix like DuraGen is an option for repairing dural tear in mastoid region.

Brain herniation in a neonate

Brain herniation is generally thought to be unlikely to occur in newborns due to the presence of the patent fontanelles and cranial sutures. A review of the literature published from 1993 to 2008 via MEDLINE search revealed no reports on neonatal brain herniation from intracranial tumour. We report a preterm Malay male infant born via elective Caesarean section for antenatally diagnosed intracerebral tumour, which subsequently developed herniation. Cerebral magnetic resonance imaging showed features that were compatible with a large complex intracranial tumour causing mass effect and gross hydrocephalus. Tumour excision was scheduled when the infant was two weeks old. Unfortunately, on the morning of the surgery, he developed signs of brain herniation and had profuse tumour haemorrhage during the attempted excision. Histopathological examination revealed an embryonal tumour, possibly an atypical rhabdoid/teratoid tumour. This case illustrates that intracranial tumours in newborns can herniate and should therefore be closely monitored.

Low circulating level of CD133+KDR+cells in patients with systemic sclerosis

BACKGROUND

Results of previous studies on the level of circulating endothelial progenitor cells (EPCs), which are involved in vascular repair, in scleroderma (SSc) patients have been controversial.

OBJECTIVES

To enumerate circulating EPC subsets and to examine their relation with endothelial dysfunction, biochemical markers of endothelial injury and vascular outcome in SSc patients.

METHODS

Enumeration of circulating CD34+KDR+ and CD133+ KDR+EPCs was performed by flow cytometry. Endothelium-dependent vasodilation was evaluated by changes in flow-mediated dilation (FMD%) in the brachial artery. Serum level of vascular endothelial growth factor (VEGF) was measured by enzyme linked immunosorbent assay.

RESULTS

SSc patients (n=52) were found to have significantly lower CD133+KDR+EPCs (3.0 vs. 7.0/μl, p<0.001) as well as FMD% (4.8% vs. 7.8%, p<0.001) compared with age and sex-matched controls (n=52). Among patients who had no concomitant cardiovascular risk factors (n=28), CD133+KDR+ EPC level was significantly lower than controls (3.8 vs. 7.3/μl, p=0.001) and correlated modestly with FMD% (r=0.29, p=0.03). Disease duration was the only determining factor identified for circulating CD133+KDR+ EPCs (p=0.03) by logistic regression analysis. Levels of serum VEGF (p=0.92) and KDR expression were not different between patients who had early and intermediate/late disease. Circulating CD34+KDR+ EPCs was not different between SSc patients and controls and did not correlate with any clinical or biochemical parameter.

CONCLUSIONS

Lower circulating CD133 +KDR+ EPC subset was found in SSc patients and correlated with impaired endothelium-dependent vasodilation in patients without cardiovascular risk factors suggesting a potential role of deficient EPC recruitment contributing to endothelial dysfunction in this disease.

Bacille Calmette-Guérin osteomyelitis of the proximal femur

All newborns in Hong Kong are given bacille Calmette-Guérin vaccinations. Reported complications include formation of regional and extra-regional localised abscesses, osteomyelitis, and lymphadenitis. Several cases of bacille Calmette-Guérin osteomyelitis have been reported in Europe, but there are few reports of this in Asia. To the author's knowledge, this is the first case report of bacille Calmette-Guérin osteomyelitis in Hong Kong. Bacille Calmette-Guérin osteomyelitis, although rare, should be kept in mind as a potential complication of bacille Calmette-Guérin vaccination. Clinical suspicion, early diagnosis using an image-guided tissue biopsy and polymerase chain reaction study, and early commencement of chemotherapy are key to the effective management of this problem.

Concordance between side-stream end-tidal carbon dioxide and arterial carbon dioxide partial pressure in respiratory service setting

OBJECTIVE

To explore the correlation and concordance between end-tidal carbon dioxide and arterial carbon dioxide partial pressure, and confirm the experience of the general consensus among service environments.

DESIGN

A prospective cross-sectional analysis.

SETTING

Two respiratory service units in Hong Kong.

PARTICIPANTS

Two hundred respiratory patients were recruited, in whom 219 sets of observations were recorded. Patients deemed to require arterial blood gas determination also had their end-tidal carbon dioxide partial pressure measured at that time, using two LifeSense LS1-9R Capnometers.

MAIN OUTCOME MEASURES

The agreement of end-tidal carbon dioxide partial pressure and arterial carbon dioxide partial pressure was studied by correlation coefficients, mean and standard deviation of their difference, and the Bland-Altman plot.

RESULTS

Overall, the correlation was low and insignificant (r=0.1185, P=0.0801). The mean of the difference was 7.2 torr (95% confidence interval, 5.5-8.9) and significant (P<0.001). The limits of agreement by Bland-Altman analysis were -18.1 to 32.5 torr, which were too large to be acceptable. In the sub-group on room air, the mean difference was reduced to 2.26 torr, the correlation between end-tidal carbon dioxide partial pressure and arterial carbon dioxide partial pressure was 0.2194 (P=0.0068), though statistically significant, the extent of correlation was still low.

CONCLUSION

End-tidal carbon dioxide partial pressure did not show significant correlation or concordance with arterial carbon dioxide partial pressure, especially when supplemental oxygen was used. End-tidal carbon dioxide partial pressure currently cannot replace arterial blood gas measurement as a tool for monitoring arterial carbon dioxide partial pressure. Possible reasons for the discrepancy with previous studies include small sample size in previous studies, lack of research facilities in service settings, and publication bias against negative studies.

LARG at chromosome 11q23 has functional characteristics of a tumor suppressor in human breast and colorectal cancer

Deletion of 11q23-q24 is frequent in a diverse variety of malignancies, including breast and colorectal carcinoma, implicating the presence of a tumor suppressor gene at that chromosomal region. We examined a 6-Mb region on 11q23 by high-resolution deletion mapping, using both loss of heterozygosity analysis and customized microarray comparative genomic hybridization. LARG (leukemia-associated Rho guanine-nucleotide exchange factor) (also called ARHGEF12), identified from the analysed region, is frequently underexpressed in breast and colorectal carcinomas with a reduced expression observed in all breast cancer cell lines (n=11), in 12 of 38 (32%) primary breast cancers, 5 of 10 (50%) colorectal cell lines and in 20 of 37 (54%) primary colorectal cancers. Underexpression of the LARG transcript was significantly associated with genomic loss (P=0.00334). Hypermethylation of the LARG promoter was not detected in either breast or colorectal cancer, and treatment of four breast and four colorectal cancer cell lines with 5-aza-2'-deoxycytidine and/or trichostatin A did not result in a reactivation of LARG. Enforced expression of LARG in breast and colorectal cancer cells by stable transfection resulted in reduced cell proliferation and colony formation, as well as in a markedly slower cell migration rate in colorectal cancer cells, providing functional evidence for LARG as a candidate tumor suppressor gene.

Cost of medical education, financial assistance and medical school demographics in Singapore

INTRODUCTION

Medical tuition fees have been rising in many countries, including in Singapore. No formal study has been conducted to evaluate the financial situation of medical students in relation to the cost of medical education in Singapore. This study was conducted to determine the financial profile of Singaporean medical students and the financial expenses they incur over the five-year duration of their undergraduate medical course.

METHODS

A questionnaire study was conducted among Year one to Year five medical students in the Yong Loo Lin School of Medicine, National University of Singapore. The following quantifiable parameters were analysed: monthly household income, financial assistance, monthly allowances and expenses.

RESULTS

64.3 percent (735) of the 1,143 undergraduates completed the survey. 21.9 percent came from families with a monthly income of less than S$3,000, with another 26.2 percent from families with monthly incomes of S$3,000-S$5,000. The total tuition fees for a five-year medical course amounted to S$87,450. The average annual expenditure of medical students amounted to S$4,470. 31.1 percent of respondents were on loans. 14.6 percent received scholarships or bursaries.

CONCLUSION

A five-year medical course can cost more than S$100,000 and pose a significant financial burden for students. The proportion of students who came from lower-income families was lower in medical school than at the national level, while the proportion from high-income families was significantly higher than at the national level. A significant proportion of students took loans to pay for tuition, and a smaller percentage was under scholarships and bursaries. More substantial financial assistance is required, particularly for students from lower-income families.

Prenatal screening for retinoblastoma in Hong Kong

We report the first use in Hong Kong of molecular techniques to screen prenatally for retinoblastoma and review 17 cases of retinoblastoma seen at the Hong Kong Eye Hospital from 2001 to 2006. A pregnant couple whose first child had retinoblastoma requested prenatal screening for retinoblastoma during their second pregnancy in 2000. Whole RB1 coding gene sequencing was performed on peripheral blood cells taken from family members and cultured amniocytes collected from the foetus during the 14th week of gestation. No RB1 gene mutations were found in the amniocyte samples and at birth the baby had no evidence of ocular tumours. During 5 years of follow-up the child remained healthy with intact visual function. Prenatal diagnosis of retinoblastoma alleviates parental stress and improves the perinatal care of affected family members.

Do-not-resuscitate decision: the attitudes of medical and non-medical students

OBJECTIVES

To study the attitudes of both medical and non-medical students towards the do-not-resuscitate (DNR) decision in a university in Hong Kong, and the factors affecting their attitudes.

METHODS

A questionnaire-based survey conducted in the campus of a university in Hong Kong. Preferences and priorities of participants on cardiopulmonary resuscitation in various situations and case scenarios, experience of death and dying, prior knowledge of DNR and basic demographic data were evaluated.

RESULTS

A total of 766 students participated in the study. There were statistically significant differences in their DNR decisions in various situations between medical and non-medical students, clinical and preclinical students, and between students who had previously experienced death and dying and those who had not. A prior knowledge of DNR significantly affected DNR decision, although 66.4% of non-medical students and 18.7% of medical students had never heard of DNR. 74% of participants from both medical and non-medical fields considered the patient's own wish as the most important factor that the healthcare team should consider when making DNR decisions. Family wishes might not be decisive on the choice of DNR.

CONCLUSIONS

Students in medical and non-medical fields held different views on DNR. A majority of participants considered the patient's own wish as most important in DNR decisions. Family wishes were considered less important than the patient's own wishes.

Examining the effect of publishing of bill sizes to reduce information asymmetry on healthcare costs

INTRODUCTION

Information asymmetry has been offered as a reason for unnecessarily high costs in certain industries where significant information asymmetry traditionally exists between providers and consumers, such as healthcare. The purpose of this paper is to examine the impact of the introduction of publishing of bill size as a means to reduce healthcare costs. Specifically, we aim to examine if this initiative to decrease information asymmetry on healthcare prices between healthcare providers and patients, and between healthcare providers themselves, will lead to lower prices for patients.

METHODS

Bill size data of 29 commonly occurring diagnosis-related groups (DRGs) for two ward classes (B2 and C) over a 16- month period were studied. Each ward class was studied separately, i.e. involving 58 DRG data sets. The mean bill size data as well as that of 50th and 90th percentile bill sizes were examined. The study involved some 46,000 inpatient episodes which occurred in the five public sector acute general hospitals of Singapore.

RESULTS

Mean prices dropped by 4.14 percent and 9.64 percent for B2 and C classes, respectively. 50 out of 58 DRG data sets showed a drop in prices. Bill sizes at the 50th percentile dropped by 7.95 percent and 10.12 percent for B2 and C classes, respectively; while at the 90th percentile, the corresponding figures were decreases of 8.01 percent and 11.4 percent for the two ward classes.

CONCLUSION

The act of publishing bill sizes has led to less information asymmetry among providers, thereby facilitating more competitive behaviour among hospitals and lower bill sizes.

Changes in refraction and ocular dimensions after cataract surgery and primary intraocular lens implantation in infants

PURPOSE

To study refraction and axial length changes after cataract extraction and primary intraocular lens (IOL) implantation in children younger than 1 year of age.

SETTING

Two regional hospitals.

METHODS

After determining the IOL power for emmetropia, 80% of the value was used to choose the IOL for implantation to counter anticipated myopic shift with age. The main outcome measures were changes in refraction and axial length 3 years after surgery.

RESULTS

Thirty-four eyes of 20 children (mean age 6.7 months +/- 3.9 [SD]) were studied. Refraction in the immediate postoperative period was +4.53 +/- 1.45 diopters (D). Three years after surgery, the mean refraction was -2.49 +/- 3.08 D (P<.001). Twenty-two eyes (64.7%) had surgery during the first 6 months of life (group 1) and had a shorter axial length at surgery (mean 18.92 +/- 1.32 mm) compared with 12 eyes (35.3%) that received surgery between 7 and 12 months (group 2, mean 20.29 +/- 1.00 mm) (P = .007). However, the final axial length was greater in group 1 (mean 22.67 +/- 1.04 mm) than in group 2 (mean 21.23 +/- 0.26 mm) (P = .019).

CONCLUSIONS

Primary IOL implantation is an option for children having cataract surgery in the first year of life. Significant myopic shifts occurred, and this seemed to be more pronounced in younger children. It appears that rethinking current strategies for IOL power calculation may be required to achieve more optimal refractive outcomes.

Paediatric tracheostomy in Hospital University Kebangsaan Malaysia - a changing trend

Indication for pediatric tracheostomy has changed. Upper airway obstruction secondary to infectious disorders is no longer the commonest indication. The aim of this study was to establish data on indications, outcome and complications of pediatric tracheostomy. A retrospective analysis of pediatric tracheostomies carried out between March 2002 to March 2004 was done. Eighteen patients were identified. The commonest indication was prolonged ventilation (94.5%) followed by pulmonary toilet (5.5%). None was performed for upper airway obstruction. Postoperative complications were encountered in six patients (33.3%), the commonest being accidental decannulation notably in children less than six years of age. Twelve patients (66.6%) were successfully decannulated. The mortality rate was 16.6%. All death were non tracheostomy related. The commonest indication for tracheostomy was prolonged ventilation and tracheostomy in children is relatively safe despite complications.

[Maggot therapy for treatment of severe infections in trauma surgery: "back to the future!"]

The ancient method of larval therapy for treatment of acute and chronic infections has become a revival and a new dimension with introduction of the Biobag (Vitapad). With use of this therapy trauma patients suffering infectious complications can be treated very effective, which can reduce the overall time needed for treatment and can result in diminished invalidity.

Long-term results of autogenous palmaris longus frontalis sling in children with congenital ptosis

PURPOSE

To investigate the long-term outcome of using autogenous palmaris longus tendon (PLT) sling for correcting congenital ptosis in children.

METHODS

This is an observational case series involving 15 eyelids of 14 consecutive children with congenital ptosis who underwent frontalis suspension surgery using PLT in a university teaching hospital.

RESULTS

One child had bilateral ptosis and the other children had unilateral ptosis. The age of patients at the time of surgery ranged from 2 to 7 years, with an average of 4.7 years. At a mean follow-up of 92 months (range, 80-104 months), all eyelids were successfully corrected with good lid height. No recurrence or other postoperative complications were encountered except one patient who developed a small skin fold over the PLT harvest site.

CONCLUSION

Long-term lid position is remarkably stable after surgical correction using PLT. PLT sling appears to be a safe and effective treatment for children with congenital ptosis requiring frontalis sling operation. It could be a good alternative to autogenous fascia lata, and further studies, to compare these two sling materials seem warranted.

A case of Langerhans' cell histiocytosis of the lung presenting with haemoptysis

Langerhans' cell histiocytosis of the lung can be part of a multisystem disorder or an isolated disorder. Ninety percent of adult patients with Langerhans' cell histiocytosis of the lung are smokers. This article reports a case of Langerhans' cell histiocytosis presenting with haemoptysis. The diagnostic signs on chest X-ray, high-resolution computed tomography, and histology are highlighted, followed by a short review of the literature.

Multiple giant duodenal gallstones causing gastric outlet obstruction: Bouveret's minefield revisited

Gastric outlet obstruction caused by a gallstone impacted in the duodenum is a rare entity known as Bouveret's syndrome. We report the unusual case of multiple large gallstones impacted in the duodenum from a cholecystoduodenal fistula in an 83-year-old lady. A high index of suspicion allowed for prompt diagnosis. Early surgical intervention was instituted because if the size and number of gallstones with an excellent outcome. The surgical strategies and underlying pitfalls underlying the management of this syndrome are critically reviewed and discussed.

Founder mutation in the BRCA1 gene in Malay breast cancer patients from Singapore

The mutation spectrum of the BRCA1 gene among ethnic groups from Asia has not been well studied. We investigated the frequency of mutations in the BRCA1 gene among Malay breast cancer patients from Singapore, independent of family history. By using the protein truncation test (PTT) and direct sequencing, BRCA1 mutations were detected in 6 of 49 (12.2%) unrelated patients. Four novel missense mutations in exon 11, T557A (1788A>G), T582A (1863A>G), N656S (2086A>G) and P684S (2169C>T) were identified in one patient. Two patients had missense mutations in exon 23, V1809A (5545T>C), which has been previously detected in individuals from Central and Eastern Europe. Three unrelated patients had the deleterious 2846insA frameshift mutation in exon 11. Methylation specific PCR (MSP) of the promoter region of the BRCA1 gene detected hypermethylation of tumor DNA in an additional 2 patients. Haplotype analysis using the microsatellite markers D17S855, D17S1323 and D17S1325 revealed a common haplotype for the three unrelated patients and their three relatives with the 2846insA mutation. These findings strongly suggest that the 2846insA mutation, the most common deleterious mutation in this study, may possibly be a founder mutation in breast cancer patients of Malay ethnic background.

Single institution's initial experience with sentinel lymph node biopsy in breast cancer patients

BACKGROUND

The sentinel lymph node is the first draining node from a cancer-bearing area and is therefore the first to manifest metastasis. In breast cancer it has been shown to predict the axillary status. Axillary dissection provides information determining prognosis and need for adjuvant therapy but carries a certain morbidity. Our aim was to determine the feasibility of detecting the sentinel node in a teaching hospital and whether the sentinel node accurately predicts the axillary status.

METHODS

All patients with stage I and II breast cancer and non-palpable axillary nodes were eligible, including those with previous excision biopsy. We excluded pregnant women, those with previous axillary surgery and women with advanced breast cancer with enlarged axillary nodes. The sentinel node was detected with technetium-99m-labelled tin colloid and vital blue dye and removed, and axillary clearance was performed.

RESULTS

A total of 312 patients were examined from August 1996 to December 1998. The mean age was 53 years (range 28-83) and mean tumour size 2.6 cm (range 0.2-9.0). The detection rate of the sentinel node was 86%. The sentinel lymph node predicted the axillary status with a sensitivity of 83% and specificity of 100%. The false-negative rate was 16.7%.

CONCLUSIONS

Detection of the sentinel lymph node is feasible and it can accurately predict the nodal status of the axilla. However, the high false-negative rate precludes as yet the use of sentinel lymph node biopsy in replacing axillary clearance as the standard of care for breast cancer.