Contemporary review of the management of left ventricular thrombus

Funding Acknowledgements

Type of funding sources: None.

Introduction

Left ventricular thrombus (LVT) is a known complication of acute myocardial infarction (AMI) and other cardiomyopathies. LVT increases the risk of stroke and systemic embolism, hence treatment with oral anticoagulation is indicated. While the initial treatment options for LVT is clear, the management of patients after the initial duration of anticoagulation is more complex and varied.

Purpose

We aimed to undertake a comprehensive literature review to study the currently available evidence regarding not only the initial type and duration of anticoagulation for LVT, but also potential treatment options after the initial period of anticoagulation in the setting of both LVT persistence and resolution.

Methods

MEDLINE, EMBASE, Scopus, and Google Scholar were searched from inception to August 2022. Data from randomized controlled trials (RCTs), observational studies and case series discussing management of LVT were included in this summarized synthesis.

Results

Of 2050 studies screened, 30 studies (24 observational studies, 3 case series, 2 RCTs, 1 non-randomized, open-label trial) were included. A total of 17 studies compared warfarin with direct oral anticoagulants (DOACs) for the initial anticoagulation strategy, with the vast majority showing similar outcomes (Table 1). Half (n = 9/18) of the studies repeated imaging between 3-6 months. All studies (n=30) used transthoracic echo with or without contrast as the imaging modality of choice, with selected patients undergoing computed tomography (CT) or cardiac magnetic resonance (CMR). If the LVT persisted, most studies recommended continuing anticoagulation (n = 11/16, 69%) or switching to a different class of anticoagulants (n = 6/16, 38%). In the event of LVT non-resolution, high-risk features of embolization (protruding, mobile vs layered clot) may aid in the discussion of risk and benefit of long-term anticoagulation. Even upon resolution of the LVT, some studies (n=5) recommend continuing anticoagulation in the presence of high-risk features of recurrence (eg. persistently depressed left ventricle ejection fraction (LVEF) and/or apical wall dyskinesis). Regardless, medical management should be optimized together with the appropriate revascularization strategy as clinically indicated.

Conclusions

Current evidence on the management of LVT is limited. This updated review summarizes the available evidence for the management for LVT. Evidence-based recommendations on the management of these patients is warranted to appropriately guide clinicians.

Comparison of adhesive single-lead cardiac ECG patch device with Holter monitoring for detecting atrial fibrillation after an acute cerebral ischemic event: An interim analysis

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health Malaysia

Background

Stroke secondary to atrial fibrillation (AF) is common and often associated with higher risk of stroke recurrence. Detection of AF is challenging due to brief unpredictable episodes of AF runs, especially in patients whose admission electrocardiogram (ECG) demonstrates a sinus rhythm. Probability of AF detection may be higher with early initiation of prolonged ECG monitoring.

Purpose

To compare diagnostic yield of 7-day cardiac ECG patch versus 24-hour Holter monitoring for detecting AF≥30 seconds; to identify predictors of AF in stroke patients; to determine if 7-day cardiac ECG patch results in a change in clinical practice.

Methods

In this investigator-initiated prospective study with pairwise comparison of 24-hour Holter and 7-day cardiac ECG patch monitoring, 150 patients who were admitted to a tertiary referral centre with acute ischemic stroke (AIS) or transient ischemic attack (TIA) within 1 week, without known AF, and had sinus rhythm in the admission 12-lead ECG were enrolled. Each patient underwent simultaneous 24-hour Holter and 7-day cardiac ECG patch monitoring. Routine transthoracic echocardiography was performed on each patient to assess cardiac function and exclude intracardiac thrombus.

Results

There were 102 (68.0%) male patients. 12 (8.0%) patients had underlying history of coronary artery disease; 26 (17.3%) had recurrent stroke or TIA. On admission, median NIH Stroke scale was 4; 18 (12.0%) patients had thrombolysis with alteplase. On transthoracic echocardiography, none had intracardiac thrombus.

Both Holter and cardiac ECG patch monitoring were initiated simultaneously at median 2 days after index stroke event. Of 150 patients, 17 (11.3%) detected AF ≥30 seconds. Of these 17 patients, 7 (4.7%) had AF detected within the first 24 hours on both Holter and cardiac ECG patch; 10 (6.7%) were detected after 24 hours on cardiac ECG patch only. Number needed to screen to detect one AF was 6. Compliance to 7-day cardiac ECG patch monitoring was 81.3%.

There was no significant difference in age among patients with and without AF. Although left atrium (LA) was not found to be dilated in patients with AF, LA volume index was significantly higher (28.3±15.9 vs 21.8±8.5, p=0.018) and LA emptying fraction (LAEF) was significantly lower (38.0%±30.2 vs 52.6%±16.7, p=0.007). The prolonged 7-day cardiac ECG monitoring patch resulted in 1.5-fold increase in prescription of anticoagulation therapy.

Conclusions

A 7-day cardiac ECG patch monitoring detected more patients with AF ≥30 seconds than 24-hour Holter monitoring and resulted in increase in prescription of anticoagulation therapy. Higher LA volume index and lower LA emptying fraction were predictors of AF in patients with a recent stroke.

Performance and 12 month outcomes of a wire free fractional flow reserve system for assessment of coronary artery disease, first experience in south east asia

Funding Acknowledgements

Type of funding sources: None.

Background

Fractional flow reserve (FFR) using an invasive pressure wire has a Class 1A recommendation for guiding coronary revascularization in stable coronary artery disease (CAD). Angiography based ‘wire free’ FFR is an emerging technique which determines the physiological significance of a coronary lesion without requirement of a pressure wire or induction of hyperemia. It also eliminates potential complications associated with introduction of wires into the coronary arteries.

Objective

To assess the 12-month clinical outcomes of PCI deferral, guided by an angiography based fractional flow reserve (CAFFR) system. The primary end point was a composite of death from any cause, myocardial infarction (MI) or target vessel revascularization (TVR)

Methods

This was a prospective, single center study involving 69 patients (93 vessels) with angiographic stenosis of 30%-90%. Patients with CAFFR of <0.80 or poor image quality were excluded leaving 29 patients (31 vessels) for analysis. All recruited patients had a CAFFR >0.80 and thus, PCI deferral.

Wired FFR was done for comparison on 14 patients (48%) at the operator’s discretion.

Results

The mean age was 59 ± 12.6 years old. Majority of patients (83%) were male. 12 (42%) patients were diabetic, 18 (62%) were hypertensive, 17 (59%) had dyslipidemia and 18 (62%) had a smoking history. The mean LVEF was 52+/-11.4%. 72% of the patients had a recent acute coronary syndrome. We assessed the LAD artery in 15 (52%) vessels. The mean CAFFR and FFR was 0.87 ± 0.04 and 0.89 ± 0.05 respectively. The values showed agreement with each other with no statistically significant proportional bias on the Bland Altman plot (linear regression t test: t=-1.19, p = 0.257). CAFFR values >0.80 showed 100% correspondence to negative FFR values (>0.80). There were zero procedural complications from CAFFR measurement.

At 12 months, all 29 patients were alive. Only 1 patient (3.4%) met the primary end point (TVR for angina). 89.6% (26) patients remained in CCS class 1 on follow up.

Conclusion

CAFFR shows good agreement with wired FFR. The 12-month outcome data shows that CAFFR guided PCI deferral is safe and comparable to the gold standard of wired FFR guided PCI deferral. Further analysis with a larger patient pool and longer follow-up is warranted. Abstract Figure. Bland-Altman plot of FFR and CAFFR

Three year clinical outcomes of fractional flow reserve guided coronary revascularization using a monorail pressure sensor microcatheter

Funding Acknowledgements

Type of funding sources: None.

Background

Fractional flow reserve (FFR) has a Class 1A recommendation for guiding coronary revascularization in stable coronary artery disease. Deferral of revascularization for coronary stenosis of FFR >0.80 has shown favorable long-term outcomes, yet the adoption in real-world practice is limited. To date, there is no study on FFR guided PCI in the Malaysian population.

Objective

(1) To explore the 3-year clinical outcome of FFR guided coronary revascularization.

(2) To compare the clinical outcome of FFR guided deferral of coronary revascularization versus FFR guided revascularization. The primary outcome was a composite of all cause mortality, non fatal myocardial infarction (MI) and ischemia driven target vessel revascularization (TVR)

Results

Thirty-five patients were lost to follow up leaving 78 patients (95 vessels) for final analysis. The mean age was 59.3 ± 9.4 years old. 69 (88.5%) patients were male, 24 (30.7%) had diabetes mellitus, 58 (74.3%) had dyslipidemia, 61 (78.2%) had hypertension and 45 (57.7%) were smokers. The mean LVEF was 56.7 ± 14.7%. FFR to the LAD artery was performed in 64 (82%) patients. Based on the FFR value of 0.80, 47 (60.2%) patients had FFR guided deferral of coronary revascularization and 31 (39.7%) patients had FFR guided revascularization.

At 3 years, 11 (14.1%) patients met the primary outcome, mainly driven by all-cause mortality (11.5%). The primary outcome was met in 14.9% of FFR guided deferral versus 12.9% of FFR guided revascularization (p = 0.828). All-cause mortality was 12.7% in patients with FFR guided deferral compared to 9.7% in patients with FFR guided revascularization at 3 years (p = 0.712). 

Cox proportional hazards model did not demonstrate any independent predictors associated with the primary outcome or all cause mortality. 

Conclusion

FFR guided deferral of revascularization was safe and had comparable long-term clinical outcomes to FFR guided PCI. To our knowledge, this is the first study on long-term clinical outcome on FFR guided revascularization in Malaysia. Abstract Figure. Kaplan-Meier curve primary end point  Abstract Figure. Kaplan-Meier curve all cause mortality

Synthesis of ZnO/Au Nanorods for Self Cleaning Applications

Zinc oxide (ZnO) is a well-known semiconductor with valuable characteristics: wide direct band gap of ˜3.3 eV, large exciton binding energy of 60 meV at room temperature, high efficient photocatalyst, etc. which have been applied in many fields such as optical devices (LEDs, laser), solar cells and sensors. Besides, various low dimensional structures of ZnO in terms of nanoparticles, nanorods, nanoneedles, nanotetrapods find applications in technology and life. This material is also appealing due to the diversity of available processing methods including both chemical and physical approaches such as: hydrothermal, sol-gel, chemical vapor deposition and sputtering. In this report, ZnO nanorods are prepared by hydrothermal method assisted with galvanic-cell effect. The effect of counter electrode materials on the morphology and structure of obtained product was studied. Scanning electron microscopy (SEM) images of the product showed that counter electrodes made of aluminum offers nanorods of higher quality than other materials in terms of uniform size, high density and good preferred orientation. The as-prepared nanorods were then sputtered with gold (Au). ZnO/Au nanostructures show excellent photocatalyst activities which were demonstrated by complete photodegradation of methylene blue (Mb) under UV irradiation and high decomposition rate k of 0.011 min^-1.

P13 Safety and efficacy of sacubitril-valsartan initiation during and after acute decompensated heart failure with reduced ejection fraction

Background

The PIONEER-HF trial has demonstrated the safety of Sacubitril-Valsartan initiation during acute decompensated heart failure (ADHF) compared to Enalapril. The efficacy outcome was also addressed by the surrogate end point of reduction in NT-proBNP. However, the safety and efficacy of Sacubitril-Valsartan initiation during ADHF compared to initiation after ADHF was unknown.

Objectives

(1) To compare the safety and efficacy of Sacubitril-Valsartan initiation during ADHF(inpatient) to initiation after ADHF(outpatient). (2) To explore the echocardiogram parameters associated with Sacubitril-Valsartan initiation during ADHF(inpatient) versus after ADHF(outpatient).

Methods

We enrolled patients diagnosed with heart failure with reduced ejection fraction (HFrEF) initiated on Sacubitril-Valsartan from February 2017 to December 2018. The baseline characteristics, echocardiogram parameters (changes in LVEF and positive remodeling), composite safety outcomes (hypotension, interruption of Sacubitril-Valsartan and worsening of renal function), and efficacy outcomes (cardiac death, readmission for heart failure) were compared.

Results

Thirty-seven patients were identified out of which 21 patients started Entresto after ADHF (outpatient group) and 16 patients during ADHF (inpatient group). The median follow-up duration was 196 days (IQR: 105 to 328days). The baseline characteristics were similar between the 2 groups. Outpatient groups achieved a significantly higher maximally tolerable dose of Sacubitril-Valsartan compared to inpatient group (median 400mg/day versus 200mg/day, p = 0.008) despite a similar starting dose (median 100mg/day versus 100mg/day, p = 0.127). The composite efficacy outcomes were similar between the 2 groups (4.8% versus 18.8%, p = 0.296). The composite safety outcome was similar between the groups (18.8% versus 4.8%, HR5.70 p = 0.054, 95%CI 0.967 to 33.60). Both groups achieved a significant improvement in LVEF after initiation of Sacubitril-Valsartan therapy: mean LVEF 23.44 ± 7.88% to 34.30 ± 13.88% (p = 0.001) in outpatient group; mean LVEF 22.99 ± 11.31% to 38.81 ± 13.91% (p = 0.002) in inpatient group. Reverse remodeling (reduction of LVESV≥15%) was similar between the 2 groups (61.9% versus 50.0%, p = 0.506).

Conclusions

Among patients with HFrEF in ADHF, initiation of Sacubitril-Valsartan therapy during or after ADHF led to similar safety and efficacy. Overall, there was a significant improvement in LVEF and positive remodeling of the LV regardless of the timing of initiation of therapy.

An Electronic Nursing Patient Care Plan Helps in Clinical Decision Support

Information technology can help to improve health care delivery. The utilisation of informatics principle enhances the quality of nursing practices through improved communication, documentation and efficiency. The Nursing Profession constitutes 34% of the total workforce in the Hong Kong Hospital Authority (HA) and includes 21,000 nurses in 2012. To enhance the quality of care and patient safety in both hospitals and community care setting, it is essential that an integrated electronic decision support system for nurses is designed to track documentation and support care or service including observations, decisions, actions and outcomes throughout the care process at each point-of-care. The Patient Care Plan project was set up to achieve these objectives. The Project adheres to strict documentation information architecture to ensure data sharing is freely available. Preliminary results showed very promising improvement in clinical care.

Pre-treatment radiographic features predict root resorption of treated impacted maxillary central incisors

OBJECTIVES

To determine independent predictors of root resorption for surgical-orthodontic treatment of impacted maxillary central incisors.

SETTING AND SAMPLE POPULATION

The Department of Dentistry at Show Chwan Hospital, Changhua, Taiwan. Eighty patients with unilateral osseous-impacted maxillary central incisors receiving a surgical-orthodontic treatment.

MATERIAL AND METHODS

This is a retrospective observational study. Root resorption and its predictors were abstracted from patients' charts, pre-treatment cephalometric radiographs, and post-treatment periapical radiographs. Predictors included demographics, treatment duration, crown angle, crown height, crown depth, and root dilacerations.

RESULTS

The patients' mean age was 9.2 ± 2.3 years (6.4-20.6 years), and 60% were females. Impacted maxillary central incisors had greater root resorption than naturally erupted contralateral incisors (Δ = -2.8 mm, p < 0.001). Independent predictors of root resorption for impacted maxillary central incisors were shown by linear regression analysis to be crown height (β = -0.2, p < 0.01), crown depth (β = -0.3, p = 0.001), treatment duration (β = 0.2, p < 0.01), and root dilacerations (β = 3.1, p = 0.001).

CONCLUSIONS

Impacted maxillary central incisors had greater root resorption during surgical-orthodontic treatment than their naturally erupted contralateral incisors. Predictors of a greater root resorption were highly and deeply impacted incisors, longer treatment, and root dilacerations. These predictors may help to inform patient and family counseling before treatment.

Headache diagnosis, management and morbidity in the Singapore primary care setting: findings from a general practice survey

INTRODUCTION

We sought to determine the epidemiological features and the headache burden of headache patients in the Singapore primary care setting. Particular attention was given to the adequacy of migraine diagnosis and management as well as the utilisation of prophylactic medication by primary care doctors.

METHODS

Consenting patients who consulted participating general practice clinics with the chief complaint of headache, were administered a questionnaire incorporating demographical data, headache characteristics and burden as well as treatment patterns. For each patient, the attending doctor independently completed a second questionnaire covering diagnosis and treatment of the patient.

RESULTS

A disproportionate number of non-Chinese and females presented for headache management in the primary care setting as compared to the Singapore population at large. Migraineurs had more headache-related disability (67.3 percent) than non-migraineurs (45.7 percent). In our study setting, the IHS diagnostic criteria (38.2 percent of respondents), ID migraine (61.1 percent) and physician's diagnosis (62.0 percent) correlated poorly with each other when employed for case definition of migraine. In the study population, 22.6 percent used acute pain medication excessively (more than four days a week), 39.3 percent were dissatisfied with their current treatment and 58.3 percent had frequent headaches (more than four attacks a month). Only a minority of those in whom prophylaxis was indicated were treated appropriately.

CONCLUSION

Diagnosis of migraine is inconsistent in the primary care setting despite the condition being responsible for considerable disability. Prophylactic treatment is underutilised as a management strategy, and the risk of medication-overuse headaches is underestimated. Our results emphasise the continuing need for education of primary care physicians and the public about strategies for effective headache diagnosis and treatment.

The efficacy of preoperative versus postoperative rofecoxib for preventing acute postoperative dental pain: a prospective randomized crossover study using bilateral symmetrical oral surgery

BACKGROUND

Previous data have demonstrated that rofecoxib has good analgesic efficacy for acute postoperative dental pain. However, up to half of these patients require rescue analgesics within the first 24 hours. As the timing of analgesic interventions may be an important factor in pain control, the present study tested the hypothesis that rofecoxib administered preoperatively would improve the analgesic efficacy and reduce rescue analgesic requirements within the first 24 hours compared with postoperative administration.

METHODS

This was a double-blind, randomized, crossover study where 45 patients had each of their identical impacted mandibular third molars removed under local anesthesia on 2 separate occasions. Patients acted as their own control; one side was pretreated with rofecoxib 50 mg, 2 hours before surgery, followed by placebo 15 minutes after surgery, and the contralateral side was pretreated with placebo 2 hours before surgery and posttreated with rofecoxib 50 mg 15 minutes after surgery. The difference in postoperative pain between 2 sides was assessed by 4 primary end-points: pain intensity as measured by a 100-mm visual analogue scale hourly for 12 hours, time to rescue analgesic, postoperative analgesic consumption, and patient's global assessment.

RESULTS

Patients reported significantly lower pain scores (P = 0.04), longer time to rescue analgesic (P = 0.02), lesser postoperative analgesic consumption (P = 0.008), and better global assessment (P = 0.01) in the pretreated compared with the posttreated sides. There were significantly more patients in the pretreated group who did not required rescue analgesic within the first 24 hours (80% vs. 58%, P = 0.01), and the pain scores were extremely low in both groups during the 12 hours postoperative period (9.8 +/- 5.0 mm vs. 14.3 +/- 7.4 mm).

CONCLUSION

Rofecoxib is an excellent analgesic for preventing postoperative dental pain and when given 2 hours preoperatively rendered most patients relatively pain free, requiring no rescue analgesics on the first postoperative day.

An in vitro evaluation of PCL-TCP composites as delivery systems for platelet-rich plasma

In this study, we first investigated the in vitro degradation properties of biodegradable, bioresorbable polycaprolactone-20% tricalcium phosphate (PCL-TCP) composites immersed in simulated body fluid (SBF) and phosphate buffered saline (PBS). Then, the release profiles of the growth factors present in platelet-rich plasma (PRP) loaded onto the composites incubated in SBF and PBS were compared. Composites immersed in both buffers showed water uptake of 13.7%+/-0.75 at day 1, followed by a constant uptake of 12.1%+/-0.3 until day 12. Henceforth the water uptake declined for SBF- and increased for PBS-soaked composites. The weight loss data did not reveal any trend. SBF- and PBS-soaked samples displayed 1-2% weight loss for 2 and 5 of the ten time points measured respectively. The original protein retention (PR) of the composites was 49.1%+/-1.50. After immersion in SBF and PBS for 4 weeks, the PR was augmented to 88.5%+/-1.40 and 69.1%+/-1.40 correspondingly. PRP after activation contained 164.7+/-24.8, 194+/-43 and 18.3+/-4.75 ng/ml of TGF-beta1, PDGF-BB and IGF-1. Microscopic analysis verified the attachment of PRP to the rods and pores of the composites. Interestingly, the buffers played an important role in determining the release profiles of TGF and PDGF. Firstly, PBS-soaked composites manifested a tri-phasic burst-like profile that was absent in SBF. Secondly, SBF-soaked composites experienced delayed release of the growth factors and total release was not achieved (64.4% for TGF and 60.5% for PDGF), whereas total release was realized for PBS-soaked composites. Lastly, release profiles from SBF-soaked composites were growth factor mediated in terms of their amounts and sizes. This was not observed for PBS-soaked composites. IGF-1, on the other hand, exhibited a progressive reduction in levels over the entire experimental period for both buffers. The mechanisms of release were theorized to be a combination of diffusion, degradation and bioactivity. Since SBF is analogous to our body fluids in terms of its ionic constituents, we expect the elution profiles derived from SBF-soaked samples to more accurately emulate the in vivo situation. In conclusion, this study has deemed PCL-TCP composites as suitable delivery systems for platelet-rich plasma.

Novel PCL-based honeycomb scaffolds as drug delivery systems for rhBMP-2

This study investigated a novel drug delivery system (DDS), consisting of polycaprolactone (PCL) or polycaprolactone 20% tricalcium phosphate (PCL-TCP) biodegradable scaffolds, fibrin Tisseel sealant and recombinant bone morphogenetic protein-2 (rhBMP-2) for bone regeneration. PCL and PCL-TCP-fibrin composites displayed a loading efficiency of 70% and 43%, respectively. Fluorescence and scanning electron microscopy revealed sparse clumps of rhBMP-2 particles, non-uniformly distributed on the rods' surface of PCL-fibrin composites. In contrast, individual rhBMP-2 particles were evident and uniformly distributed on the rods' surface of the PCL-TCP-fibrin composites. PCL-fibrin composites loaded with 10 and 20 microg/ml rhBMP-2 demonstrated a triphasic release profile as quantified by an enzyme-linked immunosorbent assay (ELISA). This consisted of burst releases at 2 h, and days 7 and 16. A biphasic release profile was observed for PCL-TCP-fibrin composites loaded with 10 microg/ml rhBMP-2, consisting of burst releases at 2 h and day 14. PCL-TCP-fibrin composites loaded with 20 microg/ml rhBMP-2 showed a tri-phasic release profile, consisting of burst releases at 2 h, and days 10 and 21. We conclude that the addition of TCP caused a delay in rhBMP-2 release. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and alkaline phosphatase assay verified the stability and bioactivity of eluted rhBMP-2 at all time points.

Computer-assisted navigational surgery enhances safety in dental implantology

INTRODUCTION

Dental implants are increasingly used to restore missing dentition. These titanium implants are surgically installed in the edentulous alveolar ridge and allowed to osteointegrate with the bone during the healing phase. After osseo-integration, the implant is loaded with a prosthesis to replace the missing tooth. Conventional implant treatment planning uses study models, wax-ups and panoramic x-rays to prefabricate surgical stent to guide the preparation of the implant site. The drilling into the alveolar ridge is invariably a "blind" procedure as the part of the drill in bone is not visible. Stereotactic systems were first introduced into neurosurgery in 1986. Since then, computer-assisted navigational technology has brought major advances to neuro-, midface and orthopaedic surgeries, and more recently, to implant placement.

CLINICAL FEATURE

This paper illustrates the use of real-time computer-guided navigational technology in enhancing safety in implant surgical procedures.

OUTCOME AND CONCLUSION

Real-time computer-guided navigational technology enhances accuracy and precision of the surgical procedure, minimises complications and facilitates surgery in challenging anatomical locations.

Memory is relevant in the symmetric phase of the minority game

Minority game is a simple-mined econophysical model capturing the cooperative behavior among selfish players. Previous investigations, which were based on numerical simulations up to about 100 players for a certain parameter alpha in the range 0.1 < approximately alpha < approximately 1, suggested that memory is irrelevant to the cooperative behavior of the minority game in the so-called symmetric phase. Here using a large scale numerical simulation up to about 3000 players in the parameter range 0.01 < approximately alpha < approximately 1, we show that the mean variance of the attendance in the minority game actually depends on the memory in the symmetric phase. We explain such dependence in the framework of crowd-anticrowd theory. Our findings conclude that one should not overlook the feedback mechanism buried under the correlation in the history time series in the study of minority game.

Wealth inequality in the minority game

To demonstrate the usefulness of physical approaches for the study of realistic economic systems, we investigate the inequality of players' wealth in one of the most extensively studied econophysical models, namely, the minority game (MG). We gauge the wealth inequality of players in the MG by a well-known measure in economics known as the modified Gini index. From our numerical results, we conclude that the wealth inequality in the MG is very severe near the point of maximum cooperation among players, where the diversity of the strategy space is approximately equal to the number of strategies at play. In other words, the optimal cooperation between players comes hand in hand with severe wealth inequality. We also show that our numerical results in the asymmetric phase of the MG can be reproduced semianalytically using a replica method.

The effect of rhBMP-2 on canine osteoblasts seeded onto 3D bioactive polycaprolactone scaffolds

Our strategy entails investigating the influence of varied concentrations (0, 10, 100 and 1000ng/ml) of human recombinant bone morphogenetic protein-2 (rhBMP-2) on the osteogenic expression of canine osteoblasts, seeded onto poly-caprolactone 20% tricalcium phosphate (PCL-TCP) scaffolds in vitro. Biochemical assay revealed that groups with rhBMP-2 displayed an initial burst in cell growth that was not dose-dependent. However, after 13 days, cell growth declined to a value similar to control. Significantly less cell growth was observed for construct with 1000ng/ml of rhBMP-2 from 20 days onwards. Confocal microscopy confirmed viability of osteoblasts and at day 20, groups seeded with rhBMP-2 displayed heightened cell death as compared to control. Phase contrast and scanning electron microscopy revealed that osteoblasts heavily colonized surfaces, rods and pores of the PCL-TCP scaffolds. This was consistent for all groups. Finally, Von Kossa and osteocalcin assays demonstrated that cells from all groups maintained their osteogenic phenotype throughout the experiment. Calcification was observed as early as four days after stimulation for groups seeded with rhBMP-2. In conclusion, rhBMP-2 seems to enhance the differentiated function of canine osteoblasts in a non-dose dependent manner. This resulted in accelerated mineralization, followed by death of osteoblasts as they underwent terminal differentiation. Notably, PCL-TCP scaffolds seeded only with canine osteoblasts could sustain excellent osteogenic expression in vitro. Hence, the synergy of PCL with bioactive TCP and rhBMP-2 in a novel composite scaffold, could offer an exciting approach for bone regeneration.

Clinico-pathological conference 2002

INTRODUCTION

Six cases are reported, each presented at the 11th Biennial Congress of the International Association of Oral Pathologists as an instructive case for differential diagnosis on the basis of clinical, imaging or histological features.

CLINICAL PICTURE

Case diagnoses included a large, possibly intraosseous, myofibroma presenting with an oral mass; Langerhans cell histiocytosis with facial skin lesions; an intraosseous vascular hamartoma of the maxilla with worrying radiological features; an unusual mixed radiolucency of the jaw caused by cemento-ossifying fibroma; an osteosarcoma of the posterior mandible causing a well-defined radiolucency and an intraoral squamous cell carcinoma in a child.

"On the other hand": a case of hereditary, congenital mirror movement

We describe a 20-year-old male Singaporean army recruit with hereditary, congenital mirror movements who presented with difficulties in military training because releasing the grip of one hand resulted in a similar release by the other hand. His father has mirror movements with a significant decrease in symptoms with time, a phenomenon that has not been previously described. Both father and son have no associated neurological abnormalities. Bilateral cortical representation for hand muscles and the presence of active ipsilateral corticospinal projections have been postulated as the mechanisms responsible for this condition.

Listeria meningoencephalitis: two cases and a review of the literature

INTRODUCTION

Although presently uncommon locally, Listeria is increasing an important cause of central nervous system (CNS) infection worldwide. It differs from the common meningitis pathogens in its clinical features and treatment.

CLINICAL PICTURE

We present 2 recently encountered cases of Listeria meningoencephalitis. In case 1, a previously healthy 42-year-old man presented with clinical features of meningoencephalitis. In case 2, a 64-year-old woman had clinical features of pneumonia and meningoencephalitis. Both had a predominantly lymphocytic picture in their cerebrospinal fluid (CSF) samples. Listeria grew in blood cultures of both patients and the CSF culture of the first.

TREATMENT

In both cases, Listeria was resistant to the empirical antibiotics used. Intravenous ampicillin was eventually used in both patients, with gentamicin, added for synergistic action in the first.

OUTCOME

The first patient developed complications of hydrocephalus, subdural collection and extensive cerebritis and ventriculitis. The second patient had focal seizures and a pontine infarct. Both did not survive.

CONCLUSION

These 2 recent cases with different presentations of intracranial listerosis highlight the increasing importance of listerial infections in Singapore. Clinicians need to be familiar with the features of this lethal disease in order to recognize and manage it successfully.

Evaluation of impulse noise criteria using human volunteer data

Four impulse noise auditory injury criteria adopted by NATO countries, namely, the MIL-STD-1474D (USA), Pfander (Germany), Smoorenburg (Netherlands), and L(Aeq8) (France), are evaluated against human volunteer data. Data from subjects wearing single-hearing protection exposed to increasing blast overpressure effects were obtained from tests sponsored by the US Army Medical Research and Material Command. Using logistic regression, the four criteria were each correlated with the test data. The analysis shows that all four criteria are overly conservative by 9.6-21.2 dB for the subjects as tested. The MIL-STD-1474D for single-hearing protection is 9.6 dB lower than the observed injury threshold for 95% protection with 95% confidence for this particular group of subjects as tested. Similar conclusions can be drawn for the other three criteria.

Familial autoimmune myasthenia gravis

Familial Autoimmune Myasthenia Gravis (FAMG) is rarely reported. We present a mother and son with late-onset mild to moderate ocular disease, low acetylcholine receptor antibody titre and the absence of a thymoma. Both responded well to low doses of anticholinesterase. HLA typing revealed that they did not share the usual HLA antigens or haplotypes with that previously reported in Caucasian and Chinese sporadic Myasthenia Gravis. Chinese FAMG may be associated with HLA antigens different from that of sporadic MG.

Wernicke's encephalopathy in patients with hyperemesis gravidarum

Our two patients presented with Wernicke's Encephalopathy (WE) resulting from prolonged hyperemesis gravidarum. This is an unusual cause of WE, a potentially fatal medical emergency due to thiamine deficiency. We discuss the clinical settings, presentation, diagnosis, neurophysiological and radiological findings, treatment and outcome of WE in these two cases and the neuropathologic correlation of this condition. We stress upon the importance of early diagnosis and prompt treatment of WE.

Headache characteristics and race in Singapore: results of a randomized national survey

This study presents the first account of the racial differences in headache prevalence and characteristics in the Singapore population. A questionnaire was administered to 2096 individuals from a randomized sample of 1400 households to test the hypothesis that race was independently correlated with headache diagnosis and morbidity. The overall lifetime prevalence of headaches in the study population was 82.7%; this did not vary between racial groups. The modal age of headache onset in all races was in the second decade and was similar in all races. Multivariate analysis showed that headache morbidity was independent of age, sex, income level, marital status, shift duties, and educational level, and correlated only with race and a positive family history of severe headache. Non-Chinese were more likely to suffer from severe headaches than Chinese, were more likely to seek medical attention, and were more likely to require medical leave for their symptoms. Non-Chinese had more migrainous headaches than Chinese, although characteristics of headache both groups experienced that were unrelated to severity differed only in a few aspects. We conclude that racial factors account for differences in headache classification, perception of headache severity and health-seeking behavior.

Perceived headache associations in Singapore: results of a randomized national survey

We attempted to discern commonly perceived associations between headache symptomatology and various clinical and social parameters based on the results of a nationwide randomized survey involving 2096 respondents. A questionnaire incorporating demographic data, headache characteristics, and management as well as basic health screening was administered by trained interviewers to those aged 12 years and older. A digital semiautomated blood pressure monitor, a Snellen chart, and urinalysis sticks were used to gather clinical information. Elevated blood pressure, poor visual acuity, and fewer hours of nightly sleep did not positively correlate with headaches of increased frequency, intensity, or duration. On the contrary, an age-dependent negative trend was observed with regard to blood pressure and visual acuity. Individuals who performed shift work had more frequent, although not more intense or long-lasting, headaches. Income had no effect on headache prevalence or severity. Our findings are at variance with common perceptions of headache in the region. They highlight the need for informed counseling of patients presenting to medical attention with headaches and suggest that serious intracranial disease should be excluded in atypical headaches even if perceived associations are present.

Axonal injury or loss in the internal capsule and motor impairment in multiple sclerosis

OBJECTIVE

To test the hypothesis that axonal damage extending into primarily normal-appearing white matter is clinically important by comparing the concentrations of N-acetylaspartate (NAA) bilaterally within the internal capsule with lateralization of motor impairment in patients with multiple sclerosis (MS) and persistent asymmetrical motor deficit.

DESIGN

We performed magnetic resonance spectroscopy and T2-weighted imaging of the internal capsule, calculated central motor conduction times, and related these results to measures of motor function asymmetry in 12 patients with MS.

RESULTS

Levels of NAA from normal-appearing white matter of the internal capsule in patients with MS were significantly lower than those in control subjects (P = .05). Side-to-side differences in NAA levels were also significantly greater in patients with MS than in controls (P = .01). There was a correlation between asymmetry in motor function for the left and right limbs and asymmetry of internal capsule NAA concentrations (r = 0.60; P = .04). This correlation seemed slightly stronger when tests specifically of arm and hand motor asymmetry were considered alone. Central motor conduction times were abnormal in most patients with MS and showed a side-to-side difference that also correlated with asymmetry in motor function.

CONCLUSION

Our demonstration of a graded association between NAA concentrations within primarily normal-appearing white matter of a specific tract and functional impairments referable to that tract suggests that axonal pathology distant from macroscopic lesions might be an important determinant of disability in MS.

Intraocular pressure variation following retrobulbar anaesthesia among the different sex, age and ethnic groups in Malaysia

A total of 114 patients (48 Chinese, 34 Malay and 32 Indian) undergoing extracapsular cataract extraction (ECCE) with intraocular lens implantation, were enrolled. All were given 3 ml of local anaesthetic (combination of equal amounts of lignocaine 2% and bupivacaine 0.5%) using retrobulbar technique. Intraocular pressure (IOP) was measured at different time intervals; before, immediately after and 5 minutes after injection with Honan balloon compression. Mean IOP increased by 5.0 mmHg immediately after injection (p < 0.001) and reduced to baseline level after 5 minutes of external compression. Although there were no statistical difference in terms of IOP variation between sex and age groups, Chinese patients demonstrated the highest IOP rise following retrobulbar anaesthesia. This is the first study to demonstrate the influence of race in the IOP response with Chinese subjects having the highest IOP rise.

Kainate receptors are involved in synaptic plasticity

The ability of synapses to modify their synaptic strength in response to activity is a fundamental property of the nervous system and may be an essential component of learning and memory. There are three classes of ionotropic glutamate receptor, namely NMDA (N-methyl-D-aspartate), AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole-4-propionic acid) and kainate receptors; critical roles in synaptic plasticity have been identified for two of these. Thus, at many synapses in the brain, transient activation of NMDA receptors leads to a persistent modification in the strength of synaptic transmission mediated by AMPA receptors. Here, to determine whether kainate receptors are involved in synaptic plasticity, we have used a new antagonist, LY382884 ((3S, 4aR, 6S, 8aR)-6-((4-carboxyphenyl)methyl-1,2,3,4,4a,5,6,7,8,8a-decahydro isoquinoline-3-carboxylic acid), which antagonizes kainate receptors at concentrations that do not affect AMPA or NMDA receptors. We find that LY382884 is a selective antagonist at neuronal kainate receptors containing the GluR5 subunit. It has no effect on long-term potentiation (LTP) that is dependent on NMDA receptors but prevents the induction of mossy fibre LTP, which is independent of NMDA receptors. Thus, kainate receptors can act as the induction trigger for long-term changes in synaptic transmission.

Changes in motor evoked potentials to short-interval paired transcranial magnetic stimuli in multiple sclerosis

OBJECTIVE

Paired transcranial magnetic stimuli (TMS) were applied in 8 multiple sclerosis (MS) patients with asymmetrical clinical signs and in 8 healthy controls to test the hypothesis that the circuits responsible for the generation and transmission of I-waves are abnormal in the former group

METHODS

A figure-of-8 coil discharging through a Magstim 200/Bistim configuration delivered identical stimuli at an intensity 10% above the motor threshold of the relaxed first dorsal interosseous muscle. The interstimulus intervals (ISIs) used were varied in a pseudo-randomized fashion in steps of 0.2 ms between 1.0 and 5 ms.

RESULTS

In 9 of 12 unilateral studies in the control group, a pattern of 3 peaks of increased motor evoked potential size was found at ISIs of 1.2-1.6 ms, 2.4-3.2 ms and 4.4-5.0 ms. A similar pattern was present in only 5 of 12 studies in the patients (Fisher's exact test, P = 0.1), while it was absent in all the 4 studies of the side with greater clinical involvement in patients (P = 0.01)

CONCLUSION

Our results suggest that I-wave generation is more likely to be defective in MS than in normal subjects, that this defect resides in the cortex, and that it correlates with severity of physical signs.

Covariation between human intrinsic hand muscles of the silent periods and compound muscle action potentials evoked by magnetic brain stimulation: evidence for common inhibitory connections

Transcranial magnetic stimuli at different stimulus intensities were applied in six healthy subjects to test the hypothesis that, in different intrinsic hand muscles, the duration of the resultant cortically evoked silent periods (C-SPs) from each stimulus would be positively correlated between muscles, indicating a common inhibitory mechanism. A figure-of-eight coil discharging through a Magstim 200 stimulator delivered 25 stimuli at each stimulus intensity at a minimum of five intensities ranging from 55% to 160% of the individual resting motor threshold. In each subject, simultaneous surface recordings from pairs of muscles were made from the first dorsal interosseous (FDI), opponents pollicis (OP), abductor pollicis brevis (APB) and abductor digiti minimi (ADM). The C-SP durations within all three muscle pairs tested were highly correlated (P<0.001). The amplitude of the preceding compound-muscle action potentials (CMAPs) was positively correlated between FDI and OP, but not between APB and ADM or FDI and ADM. C-SP duration was linearly related to stimulus intensity, but did not correlate with the latency or amplitude of the preceding CMAP. SPs elicited by peripheral nerve stimuli in pairs of hand muscles did not co-vary significantly. The results provide evidence that inhibitory influences of cortical origin are distributed widely to intrinsic hand muscles. In contrast, covariation of excitatory effects only appears between muscles synergistically involved in a motor task.

Dual effect of cobra cardiotoxin on vascular smooth muscle and endothelium

AIM

To assess the cytotoxic effects of cobra cardiotoxin (CTX) on rat aorta.

METHODS

Measure of contractility of aortic rings with or without endothelium.

RESULTS

In endothelium-intact rings, CTX 10 mumol.L-1 induced a transient relaxation followed by a sustained contraction. Removal of the endothelium or pre-incubation of the rings with NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) abolished the transient relaxation but did not affect the magnitude of the contractile response induced by CTX. CTX itself induced contraction of vascular smooth muscle but also reduced contractions induced by phenylephrine (PhE) or KCl stimulation in a concentration-dependent manner. Contraction induced by CTX was dependent on the external Ca2+ concentration. Maximal contractile response to CTX was obtained in medium containing Ca2+ 1 mmol.L-1. This response decreased with higher Ca2+ concentration and disappeared when Ca2+ 7 mmol.L-1, organic and inorganic calcium channel blockers were present in the external solution before CTX addition. In preparations with the endothelium intact and incubated with CTX, relaxation by acetylcholine (ACh) stimulation of the tension induced by PhE was decreased. Endothelium-dependent relaxation to ACh was preserved when Ca2+ 5 mmol.L-1 was added to the medium prior to CTX.

CONCLUSION

CTX first triggers the release of NO from the endothelium which results in muscle relaxation, and then causes smooth muscle contraction, Ca2+ and Ca2+ channel blockers prevented the effect of CTX.

The effect of enteral fibre-containing feeds on stool parameters in the post-surgical period

BACKGROUND/AIM OF STUDY

Specialised nutritional support includes both enteral and parenteral routes. When oral intake is not an option, but gastro-intestinal function is present, enteral tube feeding should be considered. However, one of the complications of enteral feeding access is diarrhoea. The aim of this study was to test the effect of fibre on a local population, in a prospective, single-blinded trial to determine whether the presence of fibre in enteral feeds reduced the incidence of diarrhoea in Asian patients.

METHODS

Sixteen post-surgical candidates were randomly assigned to receive a fibre-supplemented (FSF) enteral formula or a fibre-free formula (FFF) for 10 days post-surgery to assess the usefulness of FSF in reducing the incidence of diarrhoea in tube-fed patients. Differences in stool consistency, stool frequency, capillary blood glucose and serum albumin levels between the two groups were determined. Antibiotic usage in both groups was noted.

RESULTS

Patients in the FSF group had more bowel movements throughout the 10-day period and firmer stools than the FFF group, but this difference was not statistically significant (p = 0.39). There were no significant differences in daily mean glucose levels between both groups.

CONCLUSION

We conclude that there is insufficient evidence that fibre-containing enteral formulae reduce the incidence of diarrhoea in tube-fed patients in the short term. However, these products could inherently be included for patients on tube-feeds during extended periods, with the prospect of maintaining gut function integrity and flora.

Neurocysticercosis--case report and literature review

A 30-year-old Indian migrant worker presented with seizures at the National University Hospital. A CT-scan of the brain showed multiple calcifications and cysts consistent with neurocysticercosis. Plain radiographs of the humeri and femora also revealed multiple soft tissue calcifications. He was given a course of anti-helminthic therapy and started on anti-epileptics. Neurocysticercosis is a common cause of seizures in endemic areas and must be considered in the differential diagnosis of epilepsy involving the members of the large community of migrant workers in Singapore.

Headache and self-assessed depression scores in Singapore University undergraduates

A self-administered questionnaire covering the diagnostic criteria of the International Headache Society was completed by 1208 undergraduates of the National University of Singapore to determine the prevalence and characteristics of headaches in this population. The relationship between headaches and depressive illness was investigated with the Zung Self-assessed Depression Scale. The mean age of respondents was 20.9 +/- 1.6 years; 50.3% were men and 46.4%, women. Ten point nine percent had migraine without aura, 29.8% had tension-type headaches, 1.1% had headaches consistent with migraines with aura, and in 56.3% the headaches could not be classified. The lifetime prevalence of headache in this population was 98.1%. Significantly higher mean Zung scores were found in subjects who had more intense and frequent headaches than in those without headaches and less severe symptoms, although the clinical relevance of this finding is uncertain. Zung scores did not differ significantly with diagnostic group, sex, or race.

Headache characteristics in university undergraduates presenting to medical attention

A 78-point self-administered questionnaire relating to headaches was completed by 1208 undergraduates of the National University of Singapore. The management and characteristics of the study population that had sought medical consultation for their headaches was studied. The lifetime prevalence of headaches in the study population was 98.1%. One hundred and six (8.8%) had visited a doctor for their headache. These had more severe symptoms and required more pharmacotherapy. They also tended to have migraines rather than tension headaches. Malays were more likely than non-Malays to seek medical attention. No significant gender predisposition was found. Eight of the 106 (7.5%) had been given prophylactic/interval therapy. A significant proportion of the study population responds well to non-prescription medication, suggesting that the purpose of many medical consultations may be to relieve anxieties regarding the diagnosis rather than to obtain symptomatic relief.

The bulbocavernosus reflex in the assessment of neurogenic impotence in diabetic and non-diabetic men

The results of a 6-year review of bulbocavernosus reflex (BCR) latencies in 300 men are presented. The relationship of BCR latency to potency, diabetic status and age was examined. The mean BCR latency in 32 normal men aged 22 to 78 years (x = 44.9 +/- 14.4) was 40.6 +/- 8.9 ms. A significant trend towards increasing BCR latency with age was evident. BCR latency was not found to be significantly associated with potency, the mean measurable BCR latency in impotent men being 43.0 +/- 11.6 ms. Diabetic men were more likely to have a prolonged measurable BCR latency (x = 46.2 +/- 11.2) and impotence, but even in this subset no significant correlation between BCR latency and impotence was detectable. Our results suggest that detectable pudendal neuropathy is unrelated to impotence in non-diabetic and diabetic men and does not usefully distinguish between neurologic and non-neurologic causes of impotence. With the advent of newer objective techniques to assess organic impotence, the value of BCR latency in the routine assessment of impotent subjects is questionable.

Hyporesponsiveness to Ca2+ of aortic smooth muscle in endotoxin-treated rats: no-dependent and -independent in vitro mechanisms

The aim of this study was to assess the nature of vascular hyporeactivity to vasopressor agents in rats with endotoxemia. Endotoxemia was induced in rats by bacterial endotoxin (E. Coli lipopolysaccaharide, LPS). In LPS-treated rats, the reactivity of endothelium-denuded aortic rings to phenylephrine (PE) and potassium chloride (KCl) was characterized by a decreased magnitude of contraction, a slower onset of contraction and a faster rate of relaxation when compared to the control aortic rings. Addition of L-arginine (L-arg), the substrate of nitric oxide synthase (NOS), but not D-arginine (D-arg), reduced further PE-induced contraction in rings from LPS-treated rats. Inhibition of contraction in rings of LPS-treated rats was partially antagonized by the inhibitor of NOS, N omega-nitro-L-arginine methyl ester (L-NAME). Thus, production of non-endothelial nitric oxide (NO) was in part responsible for the hyporesponsiveness to PE. Rings from LPS-treated rats also displayed hyporeactivity and decreased sensitivity to Ca2+ in depolarizing medium (60 mM K+). Hyporeactivity and hyposensitivity to Ca2+ could only be partially reversed by L-NAME. The inhibitory effects of LPS-treatment on both PE-and KCl-induced aortic responses and the reversal effects of L-NAME confirm the contention that NO formation is involved in vascular hyporesponsiveness in endotoxic shock. The partial reversal by L-NAME of the hyporesponsiveness to KCl- and PE-induced contraction, and hyposensitivity to Ca2+ in depolarized aorta suggest that factors other than the action of nonendothelial source of NO formation in vitro from L-arg also contribute to endotoxin-induced vascular hyporesponsiveness to vasopressor agents.

A model of blast overpressure injury to the lung

Despite decades of animal experiments, data on blast injury to the lung cover only a limited number of circumstances and are in a fragmented form. This paper develops a mathematical model of the chest wall dynamics and the subsequent generation of strong pressure waves within the lung, which have been hypothesized as the mediator of injury. The model has been compared to an extensive database of observed pathologies from animal tests. The incidence of injury and lethality is found to follow a log-normal correlation with the computed total energy in these waves and, when the energy is normalized by the lung volume, the lethality correlation applies to all large animal species. Small animals also correlate with the normalized energy, but at a different value, and it is speculated that structural differences, other than lung volume, may be involved. This relatively simple model allows the potential for blast injury to the lung to be determined from measured or computed pressure traces without additional animal testing. Improved occupational exposure criteria should follow from this methodology.

Hemangioma of the ethmoidal sinuses

A report of a rare case of hemangioma of the ethmoidal sinuses with erosion of bony orbital wall and anterior cranial fossa. An outline of the management is presented.

Langerhans cell histiocytosis presenting as a goitre: a case report

We report a case of Langerhans cell histiocytosis (histiocytosis X) in a 36-year-old female with an euthyroid nodular goitre as the rare initial presentation. She subsequently developed a pathological fracture of the lumbar spine which was initially thought to be due to malignant infiltration, possibly from metastatic thyroid carcinoma. Open vertebral biopsy and total thyroidectomy were performed. Histological features of histiocytic proliferation with erythrophagocytosis were found in both the thyroid gland and in the involved vertebral body. The diagnosis of histiocytosis X was made on the basis of the positive immunoperoxidase staining of the histiocytic cells with S-100 and peanut agglutinin (PNA) as well as the clinical picture. Despite systemic chemotherapy with low dose corticosteroids and vinblastine, diabetes insipidus with a suprasellar mass occurred three years post thyroidectomy. Successful management of this uncommon disease is difficult to conduct and evaluate at the present time.

Soft-tissue cephalometric norms in Chinese adults with esthetic facial profiles

Using a double selection process comprised of professional and lay judges, the cephalometric tracings on a final sample of 48 Chinese adults with esthetically pleasing profiles were analyzed. The soft-tissue cephalometric norms and standard deviations of two widely accepted soft-tissue analyses, the Legan and Burstone analysis and the Holdaway analysis, were determined. In comparison with white norms, the Chinese nose was less prominent (P < .01), the nasolabial angle was less obtuse (P < .01), both the upper and lower lips were more protrusive (P < .05), the upper lip curvature was greater (P < .01), and the soft-tissue chin thickness was less (P < .05). This variance between racial types emphasizes the need to recognize that soft-tissue lateral cephalometric norms are specific for the racial group and cannot always be applied across different racial types.

Retrieval of the resilient element in an osseointegrated implant system

A fractured apical fragment of the resilient intramobile element within the IMZ dental implant cylinder is difficult to remove. The continued usefulness of the implant will be compromised if the fractured intramobile element is not removed. Two methods of retrieving the apical fragment without causing damage to the internal threads of the implant cylinder are described.

Pituitary surgery--a report of 46 cases

Resection of pituitary adenomas, by the transcranial, or more commonly, by the transsphenoidal approach is an established operation in Singapore. The authors review the results of pituitary surgery in 46 patients over a 7 year period. Forty patients had transsphenoidal surgery. Six patients had transcranial resection of their tumours. There was only one operative mortality and low morbidity. Total macroscopic resection was achieved in all but 7 patients. Eighteen of 21 patients with non-secretory adenomas had radiological evidence of cure. Normalisation of growth hormone levels was achieved in 6 out of 9 acromegalics. Three out of 6 patients with Cushing's disease had normal ACTH following surgery. Only 1 out of 6 patients was cured of her prolactinoma. Vision improved in 16 out of 25 patients with decreased vision preoperatively.

Excision of cheek leukoplakia and lining the defect with a pedicle buccal fat pad graft

The use of a pedicled buccal fat pad graft to line the cheek defect after excision of a large oral leukoplakia is described. The advantages of this fat graft over a split-thickness skin graft are discussed.

A migratory abscess pointing intraorally and extraorally. Case report

A case of migratory abscess pointing both intraorally and extraorally at a considerable distance from the causative site is reported. The anatomy of the area leading to the formation of such an abscess is described.