Systematic identification and characterization of genes in the regulation and biogenesis of photosynthetic machinery

Photosynthesis is central to food production and the Earth's biogeochemistry, yet the molecular basis for its regulation remains poorly understood. Here, using high-throughput genetics in the model eukaryotic alga Chlamydomonas reinhardtii, we identify with high confidence (false discovery rate [FDR] < 0.11) 70 poorly characterized genes required for photosynthesis. We then enable the functional characterization of these genes by providing a resource of proteomes of mutant strains, each lacking one of these genes. The data allow assignment of 34 genes to the biogenesis or regulation of one or more specific photosynthetic complexes. Further analysis uncovers biogenesis/regulatory roles for at least seven proteins, including five photosystem I mRNA maturation factors, the chloroplast translation factor MTF1, and the master regulator PMR1, which regulates chloroplast genes via nuclear-expressed factors. Our work provides a rich resource identifying regulatory and functional genes and placing them into pathways, thereby opening the door to a system-level understanding of photosynthesis.

New mouse models for high resolution and live imaging of planar cell polarity proteins in vivo

The collective polarization of cellular structures and behaviors across a tissue plane is a near universal feature of epithelia known as planar cell polarity (PCP). This property is controlled by the core PCP pathway, which consists of highly conserved membrane-associated protein complexes that localize asymmetrically at cell junctions. Here, we introduce three new mouse models for investigating the localization and dynamics of transmembrane PCP proteins: Celsr1, Fz6 and Vangl2. Using the skin epidermis as a model, we characterize and verify the expression, localization and function of endogenously tagged Celsr1-3xGFP, Fz6-3xGFP and tdTomato-Vangl2 fusion proteins. Live imaging of Fz6-3xGFP in basal epidermal progenitors reveals that the polarity of the tissue is not fixed through time. Rather, asymmetry dynamically shifts during cell rearrangements and divisions, while global, average polarity of the tissue is preserved. We show using super-resolution STED imaging that Fz6-3xGFP and tdTomato-Vangl2 can be resolved, enabling us to observe their complex localization along junctions. We further explore PCP fusion protein localization in the trachea and neural tube, and discover new patterns of PCP expression and localization throughout the mouse embryo.

A genome-wide algal mutant library and functional screen identifies genes required for eukaryotic photosynthesis

Photosynthetic organisms provide food and energy for nearly all life on Earth, yet half of their protein-coding genes remain uncharacterized^1,2. Characterization of these genes could be greatly accelerated by new genetic resources for unicellular organisms. Here we generated a genome-wide, indexed library of mapped insertion mutants for the unicellular alga Chlamydomonas reinhardtii. The 62,389 mutants in the library, covering 83% of nuclear protein-coding genes, are available to the community. Each mutant contains unique DNA barcodes, allowing the collection to be screened as a pool. We performed a genome-wide survey of genes required for photosynthesis, which identified 303 candidate genes. Characterization of one of these genes, the conserved predicted phosphatase-encoding gene CPL3, showed that it is important for accumulation of multiple photosynthetic protein complexes. Notably, 21 of the 43 higher-confidence genes are novel, opening new opportunities for advances in understanding of this biogeochemically fundamental process. This library will accelerate the characterization of thousands of genes in algae, plants, and animals.

What are the direct medical costs of managing Type 2 Diabetes Mellitus in Malaysia?

INTRODUCTION

An economic analysis was performed to estimate the annual cost of diabetes mellitus to Malaysia.

METHODS

We combined published data and clinical pathways to estimate cost of follow-up and complications, then calculated the overall national cost. Costs consisted of diabetes follow-up and complications costs.

RESULTS

Patient follow-up was estimated at RM459 per year. Complications cost were RM42,362 per patient per year for nephropathy, RM4,817 for myocardial infarction, RM5,345 for stroke, RM3,880 for heart failure, RM5,519 for foot amputation, RM479 for retinopathy and RM4,812 for cataract extraction.

CONCLUSION

Overall, we estimated the total cost of diabetes as RM2.04 billion per year for year 2011 (both public and private sector). Of this, RM1.40 billion per year was incurred by the government. Despite some limitations, we believe our study provides insight to the actual cost of diabetes to the country. The high cost to the nation highlights the importance of primary and secondary prevention.

A necessary step toward kidney donor safety: the transition from locking polymer clips to transfixion techniques in laparoscopic donor nephrectomy

Donor safety is of paramount importance in addressing end-stage renal failure through living kidney transplantation. The United States Food and Drug Administration (FDA) issued a Class II recall on the use of Hem-o-lok (Teleflex, Limerick, Pennsylvania, United States) polymer clips on the renal artery in laparoscopic donor nephrectomy (LDN) in June 2006 following 3 reported cases of donor deaths secondary to slipped ligature. The National University Hospital of Singapore made the transition regarding hilar control in minimally invasive donor nephrectomy, from using polymer and titanium clips to transfixion techniques (pure or hand-assisted laparoscopic) via laparoscopic staples or intracorporeal suturing, respectively. This study assessed safety during the transition in arterial transfixion techniques in minimally invasive donor nephrectomy for both donors and recipients. Forty-five consecutive kidney donors underwent donor nephrectomy over a 2-year period starting from June 2010. A total of 37 donors who underwent LDN (pure laparoscopic or hand-assisted laparoscopic) were included in the analysis. Of the 37 patients, 23 kidney donors had renal arterial control using Hem-o-lok while 14 patients from November 2011 onward underwent transfixion of the renal artery. The 2 groups of donor who underwent renal arterial control by either clips ligature or transfixion technique were comparable. The outcomes for the recipients in each group were similar with no statistical difference between postoperative creatinine level, incidence of delayed graft function, or graft survival at 1 year. We conclude that the transition in renal arterial control technique to transfixion techniques in LDN in line with FDA recommendation is feasible and affords equivalent donor and recipient outcomes.

A positive anti-nuclear antibody result does not contraindicate living kidney donation

Autoantibodies may precede the clinical onset of disease in up to two-thirds of patients with systemic lupus erythematosus (SLE). There is thus concern that antinuclear antibody (ANA) positivity in living kidney donors may eventuate in development of lupus nephritis post-uninephrectomy. Post-uninephrectomy, we routinely examine living kidney donors at 6 weeks, 6 months, 12 months, and annually thereafter. We performed a retrospective review of living kidney donors who had undergone uninephrectomy between July 1, 1999, and December 1, 2008. Data were collected for pre- and post-uninephrectomy renal function, proteinuria, hematuria, ANA, and anti-double stranded deoxyribonucleic acid (anti-dsDNA) antibodies. Among 68 living donor uninephrectomies performed during the study period, we excluded patients with no pre- uninephrectomy ANA or defaulted postoperative follow-up (n = 2). Twelve (18.2%) living donors were ANA-positive (M:F = 4:8) with a median titer of 1:100 (range, 1:100-1:800); 1 was transiently anti-dsDNA-positive. There were no significant differences between ANA-positive and ANA-negative donors in baseline demographics or pre-uninephrectomy creatinine clearance (median 108.0, range 79-179 mL/min vs. 106, range 58-172 mL/min, P = NS). Only 1 ANA-positive patient displayed transient microscopic hematuria (8 red blood cells); none had proteinuria pre-nephrectomy. Median follow-up was 63.5 (range, 21.2-139.3) months. At last clinic review, none of the ANA-positive donors had developed clinical symptoms or signs of SLE. Comparing ANA-positive and ANA-negative live donors at 5 years post-uninephrectomy, there were no significant differences in creatinine clearance (median 86.5, range 67-112 mL/min vs. 85.0, range 35-154 mL/min, P = NS), total urine protein (median 0, range 0-0.196 g/24 h vs 0, range 0-0.190 g/24 h, P = NS), or presence of hematuria (16.7% vs 33.3%, P = NS). Isolated ANA positivity does not contraindicate living kidney donation. Up to 5 years post- uninephrectomy, the risk of developing clinical lupus among low-titer ANA-positive individuals remains low.

De novo donor HLA-specific antibodies after heart transplantation are an independent predictor of poor patient survival

Preformed donor HLA-specific antibodies are a known indicator for poor patient survival after cardiac transplantation. The role of de novo donor-specific antibodies (DSA) formed after cardiac transplantation is less clear. Here we have retrospectively analyzed 243 cardiac transplant recipients, measuring HLA antibody production every year after transplantation up to 13 years post-transplant. Production of de novo DSA was analyzed in patients who had been negative for DSA prior to their transplant. DSA including transient antibodies were associated with poor patient survival (p = 0.0018, HR = 3.198). However, de novo and persistent DSA was strongly associated with poor patient survival (p = 0.0001 HR = 4.351). Although complement fixing persistent DSA correlated with poor patient survival, this was not increased compared to noncomplement fixing persistent DSA. Multivariable analysis indicated de novo persistent DSA to be an independent predictor of poor patient survival along with HLA-DR mismatch and donor age. Only increasing donor age was found to be an independent risk factor for earlier development of CAV. In conclusion, patients who are transplanted in the absence of pre-existing DSA make de novo DSA after transplantation which are associated with poor survival. Early and regular monitoring of post-transplant DSA is required to identify patients at risk of allograft failure.

Native renal cysts and dialysis duration are risk factors for renal cell carcinoma in renal transplant recipients

Urinary tract cancers are the third most common cancers in renal transplant recipients (RTX). This study examined the impact of dialysis duration and native renal cyst(s) (NRC) on renal cell carcinoma (RCC) occurrence among 1036 RTX followed-up from 1995 to July 2007. Abdominal ultrasonography was planned within 1-month of transplant, then every 5 years, or 2 years if renal cysts developed. Based on presence and time of development of NRC, RTX were grouped into those with no (No-NRC), new (New-NRC), preexisting (Pre-NRC) and time-indeterminate NRC (TI-NRC). Ten asymptomatic RTX were diagnosed with RCC at a median of 5.8 years posttransplant and had 5-year graft and patient survivals of 90% and 100%, respectively, following appropriate therapy. RCC occurred only in Pre-NRC and TI-NRC who had significantly longer dialysis duration than No- or New-NRC (6.7 ± 3.9 and 3.3 ± 3.2 vs. 2.7 ± 3.1 and 2.6 ± 2.4 years, respectively). These results suggest that NRC and increased dialysis duration are risk factors for RCC posttransplant. Since early treatment of RCC gives excellent outcomes, regular ultrasonography performed within a month of transplantation, then every 5 years for those without cysts and every 2 years for those with cysts for early detection of RCC is recommended.

The validation of the EQ-5D in Malaysian dialysis patients

The EQ-5D is a quality of life instrument that measures five dimensions of health. This study investigated the reliability and validity of its use in the Malaysian dialysis population. Test-retest reliability, convergent and discriminant validity were assessed. Responses of 86 subjects who completed both surveys were used in analysis. Test-retest reliability using Cohen's kappa was acceptable in four out of five dimensions, with the exception of self-care. Convergent validity was present. Discriminant validity was found in only two out of six hypotheses tested. In conclusion, the EQ-5D has potential in this population but further study is required.

Phase I study of SIR-sphere plus sorafenib as first-line treatment in patients with nonresectable hepatocellular carcinoma: The Asia-Pacific Hepatocellular Carcinoma Trials Group protocol 05 (AHCC05)

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Background: Sorafenib has been shown to significantly prolong survival in patients with nonresectable hepatocellular carcinoma (HCC) without however significant tumour regression. The addition of radio-ablative therapy could confer additional survival benefit. This phase I trial was carried out to ascertain the toxicities and safety of this combination and was designed as a prelude to a phase II trial. Methods: Eligible patients were administered SIR-sphere (max dose 3 GBq) and subsequently given Sorafenib therapy (400mg bd) either 14 days (Cohort 1: first 3 patients) or 11 days (Cohort 2: subsequent patients) later. Assessment was carried out for 30 days after commencement of Sorafenib. Results: 10 patients were recruited into this phase I trial. The second patient became ineligible for sorafenib therapy after SIR-sphere due to pulmonary bleeding not related to radio-therapy and was excluded from assessment. The characteristics of the patients are in the Table. At the end of the study period, there was no adverse events (AE) of grade 3 or 4 for Cohort 1 and 3 for Cohort 2. The only serious adverse event (SAE) recorded was from Cohort 2. Conclusions: Starting sorafenib 14 days after SIR-sphere therapy is associated fewer AEs and SAEs. The phase II trial has commenced withsorafenib starting 14 days after SIR-sphere. [Table: see text]

[Table: see text]

Phase I study of SB939 three times weekly for 3 weeks every 4 weeks in patients with advanced solid malignancies

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Background: SB939 is a novel orally bioavailable inhibitor of class 1 and 2 histone deacetylases. We conducted a phase I study to assess the safety, maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics and preliminary efficacy of SB939 in patients with advanced solid malignancies. Methods: SB939 was administered orally every other day 3 times a week for 3 consecutive weeks, in a 4-week cycle. Cohorts of patient were treated with escalating doses of SB939 starting from 10 mg. PK and PD (Acetylated Histone 3 in PBMCs) samples were collected in the first cycle. Results: 31 patients were enrolled at 10 mg (n=3), 20 mg (4), 40 mg (8), 60 mg (10) and 80 mg (6). The median number of treatment cycles received was 3.6. Fatigue, elevation of troponin T and QTc prolongation were the observed dose-limiting toxicities (DLT). At 80mg, one patient each (3/6) experienced a DLT of grade 3 fatigue, grade 3 asymptomatic elevation of troponin T and grade 3 QTc prolongation respectively. All DLTs were reversible and no treatment mortality was observed. Grade 1–2 fatigue occurred in 56% of patients occurring mainly at the 4th week, and 37% of pts had G1–2 anorexia. Grade 3–4 thrombocytopenia was observed in 2 patients at 60 mg at cycles 1 and 6 of treatment. SB939 was rapidly absorbed reaching Tmax between 1–3 h after ingestion, and mean elimination half-life and oral clearance of SB939 were 7.2 + 0.6 hrs and 53 + 8.5 L/h respectively. Cmax and AUC (0-∞) were dose-proportionally increased at this dose range. There was no substantial accumulation of SB939 on day 15 following repeated dosing. Concentrations above IC50 of SB939 for HDAC I was reached at all doses. Acetylation of H3 was dose dependent and consistent at 60mg. Of the 13 patients evaluable for response, stable disease was seen in 1 patient with follicular thyroid carcinoma and 1 with hepatocellular carcinoma for 51 and 164 days respectively. Conclusions: SB939 has similar toxicity profiles as that of other HDAC inhibitors and a favorable PK/PD profile. The MTD of SB939 in this regimen was 80 mg and 60mg is the recommended dose, at which acetylation of H3 is consistently observed. Further phase 2 studies with SB939 in specific indications are being planned.

No significant financial relationships to disclose.

Paradoxical vocal cord dysfunction: when a wheeze is not asthma

Vocal cord dysfunction (VCD) is an uncommon condition which often mimics asthma in presentation and severity. We present nine- and 11-year-old female siblings with vocal cord dysfunction, which is a dysfunction of the larynx involving unintentional paradoxical adduction of the vocal cords during inspiration. We evaluated the use of exercise testing in conjunction with pulmonary function testing in suspected vocal cord dysfunction. Although normal pulmonology function tests were elicited with the patient at rest, exercise testing revealed blunting of the expiratory loop with attenuation of the inspiratory loop unique to VCD. The child underwent video laryngoscopy in the specialised voice clinic, which confirmed vocal cord dysfunction. Exercise testing is a rapid and noninvasive means of diagnosing vocal cord dysfunction in a small subset of patients, but video laryngoscopy, with training manoeuvres to elicit paradoxical vocal cord movements in VCD, remains the gold standard of diagnosis of VCD.

Role of Tc-99m DMSA (V) scanning and serum calcitonin monitoring in the management of medullary thyroid carcinoma

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a rare disease. Serum calcitonin levels and Tc-99m DMSA (V) scans are used in the follow-up of these patients after surgical resection. We present our experience in the follow-up of these patients at a tertiary institution.

METHODS

A retrospective review of the medical records was performed. Patients with histologically-proven MTC, and who had serum calcitonin assays and DMSA (V) scans in their postoperative follow-up, were included.

RESULTS

There were 17 patients with 56 DMSA (V) scans. Four out of seven patients with elevated preoperative calcitonin measurements had calcitonin normalisation within six months of surgery, and have remained disease-free. Two patients had persistently elevated calcitonin levels after six months, which predated positive DMSA (V) scans. Results of DMSA (V) scans and serum calcitonin levels were concordant in 38 of 48 instances (79.2 percent) and discordant in 10 of 48 instances (20.8 percent). Sensitivity of DMSA (V) scans for detecting recurrence was 71.4 percent. There were no false-positive scans.

CONCLUSION

Serum calcitonin level is a sensitive and specific indicator of disease recurrence in postoperative follow-up of patients with MTC. Early (within six months) normalisation of calcitonin levels postsurgery may predict subsequent disease-free status. Discordant results between serum calcitonin levels and DMSA (V) scans may be due to undetectable lesions and follow-up scans or alternative radionuclide imaging may be required.

The changing face of food hypersensitivity in an Asian community

BACKGROUND

Food allergy seems to be increasing in Asia as well as world-wide. Our aim was to characterize food protein sensitization patterns in a population of Asian children with possible food allergy.

METHODS

Children presenting to our allergy clinic over 3 years with symptomatic allergic disease and at least one specific food allergen sensitization documented on skin prick testing were included in the analysis.

RESULTS

Two hundred and twenty-seven patients fulfilled inclusion criteria. Ninety (40%) of the positive skin tests were positive to egg, 87 (39%) to shellfish, 62 (27.3%) to peanut, 30 (13.2%) to fish, 27 (11.8%) to cow's milk, 21 (9.3%) to sesame, 13 (3.7%) to wheat and eight (3.2%) to soy. Peanut sensitization was the third most common sensitizing allergen, and seen mostly in young atopic children with multiple food hypersensitivities and a family history of atopic dermatitis. The median reported age of first exposure to fish and shellfish was 6 and 12 months, respectively. The mean age at presentation of children with shellfish hypersensitivity was at 6.7 years of age. The likelihood of shellfish sensitization was increased in children with concomitant sensitization to cockroaches.

CONCLUSIONS

In contrast to previously reported low peanut allergy rates in Asia, in our review, peanut sensitization is present in 27% (62/227) of food-allergic children, mostly in patients with multiple food protein sensitizations. Temporal patterns of first exposure of infants to fish and shellfish are unique to the Asian diet. Shellfish are a major sensitizing food source in Asian children, especially in allergic rhinitis patients sensitized to cockroaches.

Sensitization to dust mites in children with allergic rhinitis in Singapore: does it matter if you scratch while you sneeze?

BACKGROUND

Previously published data established Blomia tropicalis, as the major source of allergic sensitization in asthmatic children in tropical Singapore. Objective To define the prevalence, clinical characteristics and risk factors of species-specific mite sensitization in paediatric allergic rhinitis (AR) patients in this unique environment.

METHODS

We performed a prospective evaluation of newly diagnosed AR patients, from 1 May 2003 to 30 April 2004, from the otolaryngology and allergy outpatient clinics of the Kendang Kerbau Children's Hospital in Singapore. Patients included in the study showed evidence of sensitization to at least one respiratory allergen source and completed a detailed questionnaire. Relative risk of sensitization and associated risk factors were calculated using logistic regression analysis with the forward stepwise model. Multivariate regression analysis was performed to adjust for confounding interactions. Continuous values were compared using anova, SPSS 9.0 for Windows (SPSS Inc., 1999).

RESULTS

One hundred and seventy-five patients were included, 119 (68%) males, 142 (81%) Chinese, age mean 7.9 years (range 2-16). Sixty-eight patients (39%) reported a concomitant diagnosis and/or clinical complaints of bronchial asthma and 84 (48%) of atopic dermatitis. Skin prick test results were positive for traditional house dust mites (Dermatophagoides pteronyssinus. and D. farinae mix) in 85% of patients and for B. tropicalis in 62%. Overall mite sensitization was 98%, household pets 10%, moulds 9% and food proteins 12%. By far the single most significant factor associated with Dermatophagoides sensitization in this group was the presence of allergic eczema (odds ratio (OR) 31.8%, 95% confidence interval (CI) 3.6-285, P=0.002). Allergic eczema was negatively associated with B. tropicalis sensitization (OR 0.26%, 95% CI 0.14-0.5).

CONCLUSIONS

Children with AR and concomitant atopic dermatitis show a preferential sensitization to the Dermatophagoides mites. In our population, B. tropicalis sensitization is more prominent in children with pure respiratory allergy.

Cryptographic framework for document-objects resulting from multiparty collaborative transactions

Multiparty transactional frameworks--i.e. Electronic Data Interchange (EDI) or Health Level (HL) 7--often result in composite documents which can be accurately modelled using hyperlinked document-objects. The structural complexity arising from multiauthor involvement and transaction-specific sequencing would be poorly handled by conventional digital signature schemes based on a single evaluation of a one-way hash function and asymmetric cryptography. In this paper we outline the generation of structure-specific authentication hash-trees for the the authentication of transactional document-objects, followed by asymmetric signature generation on the hash-tree value. Server-side multi-client signature verification would probably constitute the single most compute-intensive task, hence the motivation for our usage of the Rabin signature protocol which results in significantly reduced verification workloads compared to the more commonly applied Rivest-Shamir-Adleman (RSA) protocol. Data privacy is handled via symmetric encryption of message traffic using session-specific keys obtained through key-negotiation mechanisms based on discrete-logarithm cryptography. Individual client-to-server channels can be secured using a double key-pair variation of Diffie-Hellman (DH) key negotiation, usage of which also enables bidirectional node authentication. The reciprocal server-to-client multicast channel is secured through Burmester-Desmedt (BD) key-negotiation which enjoys significant advantages over the usual multiparty extensions to the DH protocol. The implementation of hash-tree signatures and bi/multidirectional key negotiation results in a comprehensive cryptographic framework for multiparty document-objects satisfying both authentication and data privacy requirements.

A personalised Healthcare Information Delivery System: pushing customised healthcare information over the WWW

Easier and focused access to healthcare information can empower individuals to make 'informed' choices and judgements about personal health maintenance. To achieve 'optimum' patient empowerment, we need to re-evaluate and potentially re-design the processes of healthcare information delivery. Our suggestion is that healthcare information should be personalised according to each individual's healthcare needs and it should be pro-actively delivered, i.e. pushed towards the individual. We present an intelligent Personalised Healthcare Information Delivery Systems that aims to enhance patient empowerment by pro-actively pushing customised, based on one's Electronic Medical Record, health maintenance information via the WWW.

An XML-Java system for HL7-based healthcare informatics

Health-Level (HL) 7 message semantics allows effective functional implementation of Electronic Medical Record (EMR)--encompassing both clinical and administrative (i.e. demographic and financial) information--interchange systems, at the expense of complexity with respect the Protocol Data Unit (PDU) structure and the client-side application architecture. In this paper we feature the usage of the Extensible Markup Language (XML) document-object modelling and Java client-server connectivity towards the implementation of a Web-based system for EMR transaction processing. Our solution features an XML-based description of EMR templates, which are subsequently transcribed into a Hypertext Markup Language (HTML)-Javascript form. This allows client-side user interfaceability and server-side functionality--i.e. message validation, authentication and database connectivity--to be handled through standard Web client-server mechanisms, the primary assumption being availability of a browser capable of XML documents and the associated stylesheets. We assume usage of the Internet as the interchange medium, hence the necessity for authentication and data privacy mechanisms, both of which can be constructed using standard Java-based building blocks.

Severe upper airway obstruction in the tropics requiring intensive care

BACKGROUND

The clinical profile of severe upper airway obstruction, a challenging acute pediatric emergency, has not been extensively documented in the developing nations of the tropics.

METHODS

The diagnostic categories, severity of illness and outcome from 63 episodes of severe upper airway obstruction in 56 children admitted to the Pediatric Intensive Care Unit between January 1994 and December 1999 were reviewed. Outcome variables studied included requirement for ventilation, mortality and complications. Severity of illness was determined with the Pediatric Risk of Mortality (PRISM) II score.

RESULTS

Viral croup (29%) was the most common diagnosis, followed by mediastinal malignancy (13%), bacterial tracheitis (11%) and Pierre Robin syndrome (11%). There were no admissions for acute epiglottitis. Thirty episodes (48%) required ventilation for a median duration of 4.0 days. Bacterial tracheitis (100%) and subglottic stenosis (100%) were the most likely diagnoses requiring ventilation. Difficulty in intubation was encountered in 13 episodes (43%) involving, in particular, patients with bacterial tracheitis (83%; P = 0.006). Only two patients required a tracheostomy. The overall mortality was 11%. The PRISM score for all categories was generally low (mean 10.3 +/- 1.0; median 9.0). Non-survivors had a significantly higher PRISM II score than survivors (27.4 +/- 9.7 vs 8.1 +/- 4.9, respectively; P = 0.002) and were more likely to include children with bacterial tracheitis and mediastinal malignancy.

CONCLUSIONS

There is marked heterogeneity in the causes of upper airway obstruction in the tropics with viral croup remaining the most common. A significant proportion required ventilation, but outcome is generally favorable, except in those with bacterial tracheitis and mediastinal malignancy.

Experience with video-assisted thoracoscopic surgery in the management of complicated pneumonia in children

PURPOSE

The aim of this study was to assess the impact of video assisted thoracoscopic surgery (VATS) in the management of empyema in children.

METHODS

This report involves cases of complicated pneumonia in children requiring surgical intervention after failure of medical treatment with antibiotics, with or without drainage from November 1997 to October 1999. The impact of VATS has been studied prospectively from October 1998 when VATS was introduced. The results have been compared with the previous year when similar cases were dealt with open thoracotomy. These 2 groups of patients with VATS (V) or without VATS (O) were studied for their progress in hospital and the final outcome.

RESULTS

A total of 39 immunocompetent children with community-acquired pneumonia were studied. There were 17 cases in O and 22 in V. There were 2 conversions to open thoracotomy in V. Both of these cases required resection of the lung parenchyma for severe necrosis and bronchopleural fistula. The mean age in years was 5.3 (O) and 4.9 (V). Parameters that were significantly less in V compared with O include timing of referral (O, 13.6 days; V, 5.3 days), number of lung resections (O, 8; V, 2), blood transfusion (O, 14; V, 2), analgesia requirements (O, 7.8 days; V, 2.9 days), postoperative length of stay in hospital (O, 10.4 days; V, 4.6 days), time to become normothermic (O, 5.6 days; V, 1.7 days); and time to removal of chest drains (O, 6.0 days; V, 2.7 days). Cosmesis is superior in cases of VATS compared with open thoracotomy. All the children recovered well on follow-up with resolution of symptoms and no recurrences.

CONCLUSIONS

(1) VATS has ushered in a new era of hope for patients with complicated pneumonia. (2) Thoracotomy, lung resections, and the attending morbidity rate have decreased. (3) Patients are being referred earlier by the physicians because the management protocol is changing.

Obstructive sleep apnea syndrome in obese Singapore children

We set out to determine the prevalence of obstructive sleep apnea syndrome (OSAS) among obese Singapore school children and identify risk factors for OSAS. This study was designed as a prospective study in three phases. Parents completed a questionnaire with regards to sleep and daytime symptoms in Phase 1. Children suspected to have OSAS based on the questionnaire and all with a percent ideal body weight (IBW) >/=180 were called for clinic visits in Phase 2. All whose percent IBW >/=180 and those in whom the physicians strongly suspected OSAS were subjected to a polysomnogram in phase 3. The children were recruited from the School Health Nutritional Clinic for obese children. The investigations were carried out at Tan Tock Seng Hospital. In all, 3,671 children were screened with the questionnaire. Of these, 146 were selected to undergo polysomnography. Twenty-six had abnormal sleep studies with apnea/hypoxia indices (AHIs) >5/hr. The significant clinical feature which correlated with OSAS was sleep sitting up (P = 0.005). The risk is higher in morbidly obese (IBW >/=180), with a prevalence of 13.3% (8/60), than in less obese children (IBW <180). One in eight (12.5%) of these children was asymptomatic and would have been missed based on the questionnaire. Presence of adenotonsillar hypertrophy led to increased risk of OSAS. The prevalence of OSAS was 0.7% (26/3,671) among the obese schoolchildren in Singapore, which is similar to the prevalence reported by others. Using discriminant analysis, the estimated prevalence increased to 5.7%. In the morbidly obese (IBW >/=180), the prevalence rate is higher at 13.3%.

Java-based framework for the secure distribution of electronic medical records

In this paper, we present a Java-based framework for the processing, storage and delivery of Electronic Medical Records (EMR). The choice of Java as a developmental and operational environment ensures operability over a wide-range of client-side platforms, with our on-going work emphasising migration towards Extensible Markup Language (XML) capable Web browser clients. Telemedicine in support of womb-to-tomb healthcare as articulated by the Multimedia Supercorridor (MSC) Telemedicine initiative--which motivated this project--will require high-volume data exchange over an insecure public-access Wide Area Network (WAN), thereby requiring a hybrid cryptosystem with both symmetric and asymmetric components. Our prototype framework features a pre-transaction authentication and key negotiation sequence which can be readily modified for client-side environments ranging from Web browsers without local storage capability to workstations with serial connectivity to a tamper-proof device, and also for point-to-multipoint transaction processes.

Sepsis, severe sepsis and septic shock in paediatric multiple organ dysfunction syndrome

OBJECTIVES

To determine the association between severity of sepsis with outcome and severity of illness in children with multiple organ dysfunction syndrome (MODS).

MATERIALS

Four hundred and ninety-five consecutive paediatric intensive care unit (PICU) admissions were analysed. multiple organ dysfunction syndrome was defined as simultaneous dysfunction of >/= 2 organ system and sepsis by the American College of Chest Physicians and Society of Critical Care Medicine Consensus Conference definition.

RESULTS

Eighty-four patients developed MODS. The incidence of sepsis, severe sepsis and septic shock in these patients was 10.7%, 23.8% and 17.9%, respectively. Worsening categories of sepsis were associated with: (1) a higher mean admission Paediatric Risk of Mortality (PRISM II): 36.6 +/- 25.9, 56.8 +/- 32.1 and 73.6 +/- 28.5%, respectively (P = 0. 005), (2) a larger number of organ dysfunctions: mean MODS index of 37%, 46% and 58%, respectively (P = 0.007), and (3) a higher mortality: 22.2%, 65% and 80%, respectively (P = 0.03).

CONCLUSION

Presence of sepsis, severe sepsis and septic shock was associated with an increasing severity of illness, increased number of organ dysfunctions and a distinct risk of mortality among critically ill children.

Telemedicine and medical informatics in the multimedia super corridor: the Malaysian vision

The practice of medicine, with its wide range of environmental conditions and complex dependencies, has long been used as a test bed for various advanced technologies. Telemedicine, as conceptualised within the Multimedia Super Corridor (MSC) context, is seen as the application of several relatively mature technologiesartificial intelligence (AI), multimedia communication and information systems (IS) amongst othersso as to benefit a large cross-section of the Malaysian population. We will discuss in general terms the Malaysian vision on the comprehensive MSC telemedicine solution, its functionality and associated operational conditions. In particular, this paper focuses on the conceptualisation of one key telemedical component i.e. the Lifetime Health Plan (LHP) system, which is eventually intended to be a distributed multi-module application for the periodic monitoring and generation of health-care advisories for upwards of 20 million Malaysians.

Respiratory syncytial virus infection in young Malaysian children

Respiratory syncytial virus (RSV) is the most important agent causing respiratory illness in the young paediatric age group.

OBJECTIVE

To determine the clinical profile and risk factors for respiratory distress in young Malaysian children with RSV infection.

METHOD

The study was a retrospective review of 185 children below the age of 24 months hospitalised with RSV infection. Respiratory distress at admission was categorised into mild, moderate and severe using a modified respiratory distress assessment instrument (RDAI) score.

RESULTS

RSV infection occurred most frequently in the 3-6 months age group with a male predominance. A small number of patients had extrapulmonary symptoms of diarrhoea (8%) and seizures (7%). Forty-seven patients (25%) had an underlying illness. The majority of patients (63%) had mild respiratory distress. All patients (8%) with severe respiratory distress required intensive care and 80% of them required assisted ventilation. The overall mean duration of hospital stay was 7.0 +/- 5.0 days. There was only one death. Risk factors associated with respiratory distress included age less than 3 months, a family history of bronchial asthma and presence of an underlying disease.

CONCLUSION

The majority of Malaysian children with RSV infection had a mild illness but a small number of them who developed severe illness had a higher incidence of respiratory failure requiring assisted ventilation.

Effects of inhaled corticosteroid on bone turnover in children with bronchial asthma

Long-term usage of systemic steroids is associated with multiple side effects. One of the major morbidities is due to its effect on bone metabolism leading to bone loss and resulting in skeletal fractures. This study was conducted to determine the effects of inhaled steroids on bone mineral density (BMD) and biochemical bone markers. Twenty-four children with frequent episodic or mild persistent asthma who satisfied the clinical criteria for starting on inhaled corticosteroids (ICS) were enrolled into the study. The BMD scan was done using dual energy X-ray absorptiometry, prior to starting ICS therapy and 6 months later. Biochemical markers of bone metabolism, (i) serum osteocalcin as a bone formation marker, and (ii) urinary deoxypyridinoline (Upd) as a bone resorption marker, were taken prior to ICS treatment and at 2 monthly intervals. The biochemical markers were all taken in the morning. Twenty-four, age- and sex-matched children with mild episodic asthma, not requiring ICS, were used as controls for the BMD measurements. The BMD scan was done upon enrollment into the study and 6 months later. Twenty-four children on ICS and 24 controls completed the study. The subjects were on a mean dose of beclomethasone dipropionate (BDP) 0.4 mg/day. One subject needed a short course of Prednisolone in the early treatment period. None of the controls needed oral steroid therapy. One child in the control group sustained a greenstick fracture after an accidental fall. The mean rate of change of BMD was 1.8% +/- 12.3 in the subjects on BDP. This was lower than the 6.1% +/- 10.6 among the control subjects. However, this difference did not reach statistical significance (P = 0.16). There was a significant increase in serum osteocalcin level after 6 months of BDP treatment from 66.83 +/- 22.71 ng/mL to 81.61 +/- 24.66 ng/mL (P < 0.005). There was a decline in Upd from 36.2 +/- 47.1 nmol/mmol creatinine to 21.4 +/- 6.92 nmol/mmol creatinine. However, this did not reach statistical significance. There was no difference in the statural gain between the subjects on ICS and their controls. This study showed that 6 months of ICS therapy (mean dose 0.4 mg/day) had no significant adverse effect on bone metabolism in asthmatic children.

Sulphite oxidase deficiency--a report of two siblings

Isolated sulphite oxidase deficiency is a rare metabolic disorder characterised by neurological abnormalities, lens subluxation and seizures. Inheritance is autosomal recessive. We report two siblings with onset of clinical symptoms at 6 months of age, progressing to severe mental retardation, spasticity and seizures which were difficult to control. One of the siblings had lens subluxation. Diagnosis is made upon the increased levels of urinary sulphite, and high plasma S-sulphocysteine and thiosulphate levels. No treatment is known to be of help. Prenatal diagnosis is possible from the analysis of uncultured chorionic villus material for sulphite oxidase.

Efficacy of bronchodilators in the treatment of bronchiolitis

Bronchiolitis is a common respiratory infection affecting young children. Much controversy revolves around the efficacy of bronchodilators in the treatment of bronchiolitis. This study was conducted to address this issue.

AIM

To determine the efficacy of bronchodilators in the treatment of bronchiolitis.

METHOD

All children less than 2 years old with bronchiolitis were randomly assigned to receive nebulisations of Salbutamol, Ipratropium bromide or normal saline. A fourth group given only humidified oxygen without nebulisation were used as a control.

RESULTS

Data were obtained for 120 patients. Fifty-one (42%) had respiratory syncytial virus (RSV) isolated from their nasopharyngeal aspirates. The demographic characteristics of the 4 groups were similar. There was no significant difference between the groups in terms of severity score, number of nebulisations required in the nebulised groups and the outcome as measured by the length of hospitalisation.

CONCLUSION

The use of bronchodilators did not alter the course of the disease and is therefore not effective in the treatment of bronchiolitis.

Excimer phototherapeutic keratectomy for recurrent granular dystrophy

PURPOSE

Corneal grafting is a standard treatment for visually disabling granular dystrophy. The visual results of this procedure are generally good, but can be marred by recurrences of granular deposits some years later. We report the results of phototherapeutic keratectomy (PTK) for recurrent granular dystrophy in three eyes from two patients and discuss the possibilities of treating de novo granular dystrophy with excimer laser.

METHODS

The records of two patients (three eyes) treated with excimer PTK for recurrent granular deposits on the donor cornea were reviewed.

RESULTS

In all cases visual acuity was improved and repeat corneal grafting avoided. No significant complications occurred although one eye had further recurrence of granular deposits which was also successfully retreated with excimer PTK. Follow-up on these cases varies between five months and three years.

CONCLUSIONS

We believe that excimer PTK offers a simple, safe and repeatable way of restoring visual acuity to most cases of recurrent granular dystrophy. Visual recovery is fast and all the incumbent problems of repeat grafting are avoided.

Correlation between saliva and serum for human immunodeficiency virus 1 and 2 antibodies using a rapid test system

Currently, human immunodeficiency virus (HIV) tests are almost totally serum based. In situations where blood is difficult or inconvenient to obtain, a substitute to venepuncture offers an attractive alternative. The prototype OraScreen saliva dipsticks were tested on 278 samples comprising 100 normals, 100 samples from persons attending a sexually transmitted disease clinic and 78 samples from persons confirmed to have HIV. The specificity and the sensitivity of the diagnostic test for saliva was 99.5% and 94.7% respectively, when compared to a routine solid-phase enzyme-linked immunosorbent assay (ELISA) test on serum samples and Western blot test when indicated. The prototype OraScreen dipstick test shows potential for saliva testing in situations where it would be inconvenient to use blood. Further evaluation of saliva testing is warranted on a large sample population with a low prevalence of HIV infection.

Evaluation of a safe-sex intervention programme among sex workers in Singapore

The purpose of this study was to evaluate the effects of a brief intervention programme on STD knowledge, condom use and gonorrhoea incidence among sex workers in Singapore. A controlled before-and-after study design with non-random assignment of sex workers was used, supplemented by multivariate analysis to adjust for baseline differences. Control (n = 221, denoted C1) and experimental (n = 221, denoted E1) groups were interviewed on 2 occasions 3 months apart. Two supplementary groups were interviewed once each at the end of the 3-month period (n = 145 who had received the intervention and n = 151 who had not). Basic knowledge of STD symptoms and HIV transmission was high in all groups. There were misconceptions about casual transmission of HIV which improved dramatically at the second interview for group E1 (from 37-56% correct responses to 82-90%). Overall condom use was high (about 75%) and did not change after the intervention. Gonorrhoea rates were correspondingly low (0.4 episodes/worker/year) and also did not change. This brief intervention improved the STD knowledge of sex workers. However, behaviour as measured by reported condom use and gonorrhoea incidence did not change. Implications for future intervention programmes are discussed.

The 'TRAP' sequence--life threatening consequences to the pump twin

The acardius foetal malformation is a rare abnormality occurring in monozygotic multiple pregnancies. This is a case report of a pair of twins with the "twin reversed arterial perfusion (TRAP)" sequence and its complications. The recipient twin was born acardius acephalus. The pump twin had problems of prematurity, disseminated intravascular coagulation, sclerema and right ventricular hypertrophy. On follow-up at seven months he has failure to thrive, spastic quadriplegia and developmental delay. An awareness of the TRAP sequence may lead to better antenatal diagnosis and optimal management of the twin pregnancy.

Current therapy of HIV associated infections and malignancies

Drug therapy in AIDS is used to prolong life as there are many infections and malignancies which appear as a consequence of the immunosuppression and these can be fatal. Current anti-virals which specifically inhibit HIV replication are being used earlier to extend quality of life, maintain immune status and reduce the prevalence of opportunisitic infections and malignancies. Some infections cannot yet be treated and new therapies are awaited. It is too early in the epidemic for significant drug resistance to emerge. However, this is to be expected in the future. The prevalence of adverse drug reactions is significantly increased and therefore newer alternatives are keenly awaited. Drug treatment of HIV infected individuals is a formidable task requiring skilled multidisciplinary approach. This review summarises the most current treatment modalities for HIV associated infections and malignancies.