The impact of diabetes mellitus on the prognostic value of a normal dobutamine stress echocardiogram in patients with intermediate to high cardiovascular risk

INTRODUCTION

There is currently limited data on the prognostic value of a normal dobutamine stress echocardiogram (DSE) in patients with intermediate to high cardiovascular risk. The impact of diabetes mellitus, recently recognised as a cardiovascular risk-equivalent, has not been previously evaluated. This study aims to determine the prognostic value of a normal DSE in these patients.

METHODS

The study population includes all patients with two cardiovascular risk factors or diabetes mellitus and a normal DSE (baseline and peak stress) with three months follow-up. A total of 122 patients (47 females, 75 males; mean age 59.6 years) were recruited. Impact of diabetes mellitus on subsequent cardiovascular events was determined.

RESULTS

Diabetes mellitus was present in 32.8 percent, hypertension in 72.1 percent, smoking in 27.0 percent, family history of premature coronary artery disease in 15.6 percent, and hypercholesterolemia in 66.4 percent. On follow-up until 6.4 years (mean 4.1 years), there were four myocardial infarctions (0.8 percent per patient/year) and five revascularisation procedures (1.0 percent per patient/year). The majority of adverse events occurred among patients with diabetes mellitus (three out of four myocardial infarctions; four out of five revascularisations). Diabetes mellitus independently predicted subsequent cardiac events on both univariate and multivariate analyses (p value is equal to 0.015 and 0.011, respectively). Presence of diabetes mellitus also conferred a worse outcome on survival analysis (p value is equivalent to 0.0046).

CONCLUSION

The presence of diabetes mellitus adversely affects clinical outcome despite a normal DSE. Patients without diabetes mellitus, but with intermediate to high cardiovascular risk, and a normal DSE have a better medium term outcome.

Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study

BACKGROUND

We investigated the temporal progression of the clinical, radiological, and virological changes in a community outbreak of severe acute respiratory syndrome (SARS).

METHODS

We followed up 75 patients for 3 weeks managed with a standard treatment protocol of ribavirin and corticosteroids, and assessed the pattern of clinical disease, viral load, risk factors for poor clinical outcome, and the usefulness of virological diagnostic methods.

FINDINGS

Fever and pneumonia initially improved but 64 (85%) patients developed recurrent fever after a mean of 8.9 (SD 3.1) days, 55 (73%) had watery diarrhoea after 7.5 (2.3) days, 60 (80%) had radiological worsening after 7.4 (2.2) days, and respiratory symptoms worsened in 34 (45%) after 8.6 (3.0) days. In 34 (45%) patients, improvement of initial pulmonary lesions was associated with appearance of new radiological lesions at other sites. Nine (12%) patients developed spontaneous pneumomediastinum and 15 (20%) developed acute respiratory distress syndrome (ARDS) in week 3. Quantitative reverse-transcriptase (RT) PCR of nasopharyngeal aspirates in 14 patients (four with ARDS) showed peak viral load at day 10, and at day 15 a load lower than at admission. Age and chronic hepatitis B virus infection treated with lamivudine were independent significant risk factors for progression to ARDS (p=0.001). SARS-associated coronavirus in faeces was seen on RT-PCR in 65 (97%) of 67 patients at day 14. The mean time to seroconversion was 20 days.

INTERPRETATION

The consistent clinical progression, shifting radiological infiltrates, and an inverted V viral-load profile suggest that worsening in week 2 is unrelated to uncontrolled viral replication but may be related to immunopathological damage.

Inflammatory pseudotumor of the heart causing aortic regurgitation

Inflammatory pseudotumor is a tumor-like reactive lesion of unknown etiology that rarely affects the heart. We describe an unusual case of a cardiac inflammatory pseudotumor that involved the aortic valve and caused regurgitation in a 62-year-old man. The lesion was excised and the aortic valve was replaced, resulting in a favorable outcome for the patient.

An efficient room-temperature silicon-based light-emitting diode

There is an urgent requirement for an optical emitter that is compatible with standard, silicon-based ultra-large-scale integration (ULSI) technology. Bulk silicon has an indirect energy bandgap and is therefore highly inefficient as a light source, necessitating the use of other materials for the optical emitters. However, the introduction of these materials is usually incompatible with the strict processing requirements of existing ULSI technologies. Moreover, as the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between components; this interconnectivity problem could restrict further increases in computer chip processing power and speed in as little as five years. Many efforts have therefore been directed, with varying degrees of success, to engineering silicon-based materials that are efficient light emitters. Here, we describe the fabrication, using standard silicon processing techniques, of a silicon light-emitting diode (LED) that operates efficiently at room temperature. Boron is implanted into silicon both as a dopant to form a p-n junction, as well as a means of introducing dislocation loops. The dislocation loops introduce a local strain field, which modifies the band structure and provides spatial confinement of the charge carriers. It is this spatial confinement which allows room-temperature electroluminescence at the band-edge. This device strategy is highly compatible with ULSI technology, as boron ion implantation is already used as a standard method for the fabrication of silicon devices.

Safety of disease modifying anti-rheumatic agents in rheumatoid arthritis patients with chronic viral hepatitis

OBJECTIVE

To examine the safety of the use of disease modifying anti-rheumatic drugs (DMARDs) in rheumatoid arthritis (RA) patients with chronic viral hepatitis (CVH).

METHODS

Records of 600 Chinese patients satisfying the ARA criteria for RA in two rheumatology centers were reviewed. Patients with CVH were studied. Liver enzymes were checked before (baseline) and during DMARD use at 3-month intervals or more frequently if necessary. Drug-episodes (D-Ep), defined as the continuous use of DMARD, singly or in combination, for more than 6 months in a patient, were analysed. Changes in serum liver alanine transaminase (ALT) levels as multiples of the upper range of normal were taken to reflect the severity of hepatotoxicity. Changes of ALT to > or = 1.5 times the upper range of normal if they were measured at baseline or > or = 2 times the upper range of normal if they were measured during and after the use of DMARD were considered as abnormal. Control patients included those with CVH alone (n = 623) or RA without CVH (n = 62) matched for age, sex and D-Ep.

RESULTS

30 RA patients were found to have concomitant CVH. One patient was excluded because of use of NSAID alone (n = 1). Among the 29 patients, 23 were HBsAg +ve and 6 were anti-HCV Ab +ve. A total of 47 D-Ep were analysed. 20/47 (42.6%) of D-Ep in 16/29 (55.2%) RA + CVH patients developed abnormal ALT levels after a mean 1.9-year duration of DMARD use. This was statistically significant when compared with 13/94 (13.8%) of D-Ep which ended with abnormal ALT levels in 13/62 (21%) patients with RA alone (p < 0.0001 for D-Ep which ended up with abnormal ALT, and p < 0.02 for the number of patients who developed abnormal ALT) and 128/623 (20.5%) patients with CVH alone (p < 0.005). 53% (9/17) of hydroxychloroquine (HCQ) D-Ep were associated with an abnormal outcome. Corresponding figures for sulphasalazine (SAZP) and oral or intramuscular gold preparations were 55.6% (5/9) and 0% (0/3) respectively. Two patients on methotrexate, used either singly or in combination, had normal ALT levels throughout the study period. One patient on azathioprine developed reactivation of hepatitis B infection. When D-Ep of the RA + CVH group were further analysed, 16/43 (37.2%) and 4/4 (100%) D-Ep which started with normal and abnormal baseline ALT respectively developed further liver enzyme derangement.

CONCLUSION

The use of DMARD in RA + CVH patients is associated with a high incidence of hepatotoxicity. The effect is likely to be synergistic. This includes drugs such as HCQ, which is generally believed to be less hepatotoxic.

Cloning and characterization of two hydrophobin genes differentially expressed during fruit body development in Lentinula edodes

Hydrophobins play important roles in morphogenesis and pathogenesis in fungi and fruit development in mushrooms. Two genes encoding hydrophobins (Le.hyd1 and Le.hyd2) were isolated during sequencing of random clones from a primordial cDNA library of Lentinula edodes. The nucleotide sequences of these two genes were determined. These two genes are 760 and 738 bp in length and the deduced amino acid sequences are homologous to various fungal hydrophobins with characteristic cysteine spacing. These hydrophobin genes are Class I hydrophobins judging by their conserved domains and hydropathy patterns. The transcript level of Le.hyd1 is high in primordium and that of Le.hyd2 is high in dikaryotic mycelial tissues. Poor expression of these two genes in monokaryotic parents indicates that these two genes are under mating-type regulation. We thus suggest that differential expression of these two L. edodes hydrophobins during fruit development may contribute to their distinct roles in fruiting of this mushroom.

Initial experience of radiofrequency catheter ablation of supraventricular tachycardia in paediatric patients

INTRODUCTION

The management of supraventricular tachycardia (SVT) in paediatric patients until recently has frequently been pharmacologic therapy, but this approach suffers from the drawbacks of treatment failure, development of drug intolerance and/or side-effects.

AIM

In keeping with recent advances in paediatric cardiology, we share our experience with radiofrequency catheter ablation as an alternative and definitive modality of therapy.

MATERIALS AND METHOD

4 young patients with recurrent SVT underwent electrophysiologic study followed by radiofrequency ablation of the accessory pathways.

RESULTS

Resolution of symptoms was achieved in all patients and no major complication was encountered.

CONCLUSIONS

The ability to ablate permanently the reentrant circuit responsible for SVT has now permitted cure by non-surgical means, and is an important alternative to drug therapy in the management of SVT in children.

Diagnosis of pacemaker lead infection using transoesophageal echocardiography: a case report

INTRODUCTION

Vegetative lead infection is an uncommon complication of permanent pacemaker implantation. The diagnosis is difficult using conventional imaging methods.

CLINICAL PICTURE

An elderly Indian woman with a history of diabetes mellitus developed Staphylococcus aureus infection after implementation of a permanent pacemaker. Following a non-diagnostic transthoracic echocardiogram, transoesophageal echocardiography was performed and showed a large vegetative mass attached to the pacemaker lead within the right atrium.

TREATMENT

The pacemaker was removed and intravenous vancomycin administered for six weeks.

OUTCOME

She was discharged well but demised two months later from a second episode of septicaemia.

CONCLUSIONS

Pacemaker lead infection remains a challenging management problem. Transoesophageal echocardiography can facilitate its diagnosis.

Negative selection: a method for obtaining low-abundance cDNAs using high-density cDNA clone arrays

The identification of the entire complement of genes expressed in a cell, tissue, or organism provides a framework for understanding biological properties and establishes a tool set for subsequent functional studies. The large-scale sequencing of randomly selected clones from cDNA libraries has been successfully employed as a method for identifying a large fraction of these expressed genes. However, this approach is limited by the inherent redundancy of cellular transcripts reflecting widely variant levels of gene transcription. As a result, a high percentage of transcript duplications are encountered as the number of sequenced clones accrues. To address this problem, we have developed a negative hybridization selection method that employs the hybridization of complex cDNA probes to high-density arrays of cDNA clones and the subsequent selection of clones with a null or low hybridization signal. This approach was applied to a cDNA library constructed from normal human prostate tissue and resulted in the reduction of highly expressed prostate cDNAs from 6.8 to 0.57% with an overall decline in clone redundancy from 33 to 11%. The selected clones also reflected a more diverse cDNA population, with 89% of the clones representing distinctly different cDNAs compared with 67% of the randomly selected clones. This method compares favorably with cDNA library re-association normalization approaches and offers several distinct advantages, including the flexibility to use previously prepared libraries, and the ability to employ an iterative screening approach for continued accrual of cDNAs representing rare transcripts.

Prostate cancer expression profiling by cDNA sequencing analysis

Prostate cancer is a frequently diagnosed solid tumor that is originated mostly from prostate epithelium. One of the key issues in prostate cancer research is to develop molecular markers that can effectively detect and distinguish the progression and malignancy of prostate tumors. Automated, single-pass cDNA sequencing was utilized to rapidly identify expressed genes in a number of cDNA libraries constructed from various normal and tumor prostatic tissues. These included cell lines as well as short-term epithelial culture. A total of 6604 expressed sequence tags (ESTs) were generated and searched against on-line nucleotide and protein databases. A relational database centric software system was constructed to process, store, and analyze EST data rapidly. cDNA contigs were also obtained by assembly of multiple EST sequences. Protein structural signatures were annotated using motif analysis tools including BLOCKS and an in-house-designed neural network. Cross-library comparisons revealed their unique gene expression profiles. Several differentially expressed cDNA clones were identified, and their expression patterns were confirmed by RNA dot blot and RT-PCR analyses.

Spontaneous aortic laceration causing flail aortic valve and acute aortic regurgitation

Spontaneous laceration of the aorta is an unusual cause of flail aortic valve. We report a case of acute aortic regurgitation caused by flail aortic valve as a result of spontaneous laceration of the ascending aorta. The role of transesophageal echocardiography in the diagnosis of this condition is discussed.

Co-existing left atrial thrombus and myxoma in mitral stenosis--a diagnostic challenge

We report an unusual case of an adult who underwent a mitral valve replacement with concomitant excision of the left atrial myxoma and thrombus. Echocardiography showed the presence of a large "thrombus" within the left atrial appendage, body and atrial septum. There was difficulty in trying to distinguish between the atrial thrombus and myxoma due to their morphological similarities. At time of surgery, frozen section confirmed the atrial septal component of the thrombus to be an atrial myxoma and the atrial septum was excised to obtain a clear margin.

Gastroesophageal reflux disease is a common cause of noncardiac chest pain in a country with a low prevalence of reflux esophagitis

Gastroesophageal reflux disease is believed to be uncommon in the East. This study aimed to determine if such a condition was a significant cause of noncardiac chest pain in Singapore. Eighty consecutive patients with recurrent chest pain, who had cardiac and other obvious causes excluded, underwent esophagogastroduodenoscopy, standard manometry, acid perfusion test, and prolonged ambulatory pH and pressure monitoring. Endoscopic esophagitis, positive acid perfusion tests, pathologic reflux, and positive chest pain-reflux correlation were detected in 7/80 (8.8%), 11/70 (15.7%), 14/61 (23.0%), and 12/25 (48.0%) patients, respectively. Among those with pathologic reflux, endoscopic esophagitis was present in only two (14.3%). Overall, 32 (40%) patients had gastroesophageal reflux disease. Esophageal motility disorder, alone or in association with gastroesophageal reflux disease, was demonstrated in only five (6.3%) patients. Our results confirmed western reports that gastroesophageal reflux disease was a common cause of noncardiac chest pain, whereas motility disorder was an infrequent cause of such pain.

Non-cardiac, non-oesophageal chest pain: the relevance of psychological factors

BACKGROUND

No cause has been determined for chest pain that is neither cardiac nor oesophageal in origin.

AIMS

To compare the prevalence of life-time psychiatric disorders and current psychological distress in three consecutive series of patients with chronic chest or abdominal pain.

PATIENTS

Thirty nine patients with non-cardiac chest pain and no abnormality on oesophagogastroduodenoscopy, oesophageal manometry, and 24 hour pH monitoring; 22 patients with non-cardiac chest pain having endoscopic abnormality, oesophageal dysmotility, and/or pathological reflux; and 36 patients with biliary colic.

METHODS

The Diagnostic Interview Schedule and the 28 item General Health Questionnaire were administered to all patients.

RESULTS

Patients with non-cardiac chest pain and no upper gastrointestinal disease had a higher proportion of panic disorder (15%), obsessive-compulsive disorder (21%), and major depressive episodes (28%) than patients with gallstone disease (0%, p < 0.02; 3%, p < 0.02; and 8%, p < 0.05, respectively). In contrast, there were no differences between patients with non-cardiac chest pain and upper gastrointestinal disease and patients with gallstone disease in any of the DSM-111 defined lifetime psychiatric diagnoses. Using the General Health Questionnaire, 49% of patients with non-cardiac chest pain without upper gastrointestinal disease scored above the cut off point (that is, more than 4), which was considered indicative of non-psychotic psychiatric disturbance, whereas only 14% of patients with gallstones did so (p < 0.005). The proportions of such cases were however similar between patients with non-cardiac chest pain and upper gastrointestinal disease (27%) and patients with gallstones.

CONCLUSIONS

Psychological factors may play a role in the pathogenesis of chest pain that is neither cardiac nor oesophagogastric in origin.

A telemedicine system for high-quality transmission of paper electrocardiographic reports

To overcome problems associated with the faxing of ECGs, we developed a telemedicine system providing fast transmission of ECGs between physicians and cardiologists at different locations. It digitized ECGs at a resolution of 300 dots/inch (118 dots/cm), processed them, and transmitted them over a standard telephone line in under one minute. The system also paged the cardiologist in order to direct him or her to the location where the ECG would be waiting for interpretation. The system enabled physicians at remote locations to consult using voice, images and simultaneous cursor pointers. A transmitting site was set up at the Medical Centre of the Ministry of Defence and a receiving site at the National University Hospital, about 5 km away. During a six-month trial, 200 ECG reports were transmitted from one site to the other. They were rated excellent in quality by the cardiologists, being virtually indistinguishable from the originals. Our telemedicine system transmits high-quality ECGs rapidly and at low cost.

An expressed-sequence-tag database of the human prostate: sequence analysis of 1168 cDNA clones

The human prostate is a complex glandular organ with functional development under hormonal regulation. Diseases of the prostate result in significant morbidity and mortality in the form of benign prostatic hypertrophy and prostate adenocarcinoma. The characterization of the molecular framework of the human prostate at the level of expressed genes will facilitate the understanding of normal and pathological prostate biology. The purposes of this study were to acquire an initial assessment of the qualitative and quantitative diversity of gene expression in the normal human prostate and to determine the extent that genes with prostate-restricted expression can be assessed using an expressed sequence tag approach. We have constructed a directional cDNA library from normal adult human prostate tissue and partially sequenced the 5' end of 1168 randomly selected cDNA clones, resulting in more than 400 kb of DNA sequence. Homology searches of the sequenced cDNAs against the GenBank and dbEST databases revealed that 43% of the sequences are identical to human genes whose functions are known, 5% are similar but not identical to known genes in humans or lower organisms, 5% match the mitochondrial genome, 9% are composed of interspersed DNA repeats, 30% are homologous to sequences in the dbEST database without a described function, and 6% are novel sequences. A total of 780 distinct species were identified. In addition to the 74 novel transcripts, 4 genes, prostate-specific antigen (PSA), prostate secretory protein (PSP), prostate acid phosphatase (PAP), and human glandular kallekrein 2 (HK2), have no homologous sequences in the databases that originate from sources other than prostate and thus may represent genes with prostate-restricted expression. Sequences matching PSA, PSP, and PAP each accounted for > 1% of the total ESTs and represent highly abundant transcripts, correlating with the abundance of these proteins in the prostate gland. No novel transcripts were represented by more than one EST and thus are expressed at levels much lower than the known prostate-specific genes.

Electrocardiographic abnormalities in right ventricular infarction associated with right bundle branch block

An 80-year-old woman with pre-existing complete right bundle branch block presented with severe chest pain. The 12-lead electrocardiogram, together with right-sided chest leads, showed complete right bundle branch block and ST segment elevation in leads II, III, aVF, V5, V6 and V4R to V6R. These electrocardiographic abnormalities indicate acute 'Q wave' inferolateral and right ventricular infarction coexisting with right bundle branch block.

Dobutamine stress echocardiography in the elderly Asian patients

Dobutamine stress echocardiography (DSE) is an established non-invasive technique for the evaluation of coronary artery disease (CAD). It has been shown to be both safe and accurate. However, its utility and safety in the elderly, in particular, elderly Asian patients has not been studied. Between September 1992 and December 1994, we performed a total of 75 consecutive DSE studies in patients over the age of 65. Of these, 50 (67%) were females. Forty-nine patients had hypertension, 26 had diabetes mellitus, 10 were smokers, 5 had a recent or previous myocardial infarction and another 4 had a history of heart failure. Indications for DSE were, inability to perform the standard treadmill exercise test (40 patients), an abnormal resting electrocardiogram (ECG) (14 patients), a prior false positive or inconclusive treadmill test, risk stratification post myocardial infarction (4 patients) or preoperative cardiac evaluation (23 patients). The test was terminated in the majority of patients following attainment of the target heart rate. Atropine stimulation was required in 61 (81%) patients. Chest pain was provoked in 11 patients. No death or myocardial infarction occurred. Minor non-cardiac symptoms occurred in another 6 patients but this did not necessitate termination of the procedure. Three patients had transient hypotension, none of which was symptomatic. Arrhythmia occurred in 23 patients but the majority were isolated atrial or ventricular premature beats (20); 1 patient had atrial fibrillation and another developed transient junctional rhythm. Only one patient developed ventricular tachycardia but this was not haemodynamically significant and terminated easily with an intravenous dose of lignocaine. A conclusive result could be obtained in 72 (96%) patients. We concluded that DSE could be performed and interpreted in the majority of elderly Asian patients studied. Despite supplemental atropine, an aggressive dosing protocol and the inclusion of patients with a myocardial scar or history of heart failure, adverse effects were rare and often did not require any specific therapy.

Bilateral ankylosis of temporomandibular joint secondary to ankylosing spondylitis in a male Chinese

A case of bilateral temporomandibular joint (TMJ) ankylosis in a Chinese male patient with ankylosing spondylitis is presented. A review of the literature emphasizes the rarity of this arthro-pathology in ankylosing spondylitis. The importance in the recognition of this complication by clinical examination supplemented by computed tomography is stressed.

High-throughput plasmid mini preparations facilitated by micro-mixing

We have developed a reliable high-throughput plasmid isolation system using a 96-well plate format. This system combines a novel glass bead micro-mixing method with modified alkaline lysis and Sephacryl S-500 DNA purification procedures. Mechanical forces generated by vortexing glass beads inside each well of the 96-well plates ensure that the bacterial pellets are homogeneously resuspended, the cells are completely lyzed, and the resulting bacterial lysates are thoroughly mixed with the potassium acetate solution. The vortexing speed and duration for glass bead mixing have been standardized to facilitate plasmid DNA yields without significant adjustments.

Dobutamine stress echocardiography: angiographic correlates

We started a dobutamine stress echocardiography (DSE) programme in September 1992. Until January 1994, we had performed 300 such procedures. Of these patients, 81 underwent cardiac catheterisation within 6 months of DSE without a cardiac event in the interim. Eleven DSEs were performed to assess myocardial viability and another 6 were inconclusive for myocardial ischaemia. The remaining 64 were correlated with the angiographic data to determine the utility of this technique in our institution. The mean age of the cohort was 57 years. Thirty-six patients were referred for DSE in the workup for chest pain, either anginiform (22) or atypical (14). Fourteen patients had a recent (6) or remote (8) myocardial infarction. Thirteen patients were asymptomatic. Significant obstructive coronary artery disease (CAD) was identified in 36 patients of whom 17 and 19 had single and multivessel disease respectively. The sensitivity of DSE in the entire cohort was 89% and the specificity 82%. Positive and negative predictive values of DSE were 86% and 85% respectively. Although the numbers involved were small, sensitivity figures for single and multivessel disease were 94% and 84% respectively. Of the patients with single vessel CAD, prediction of the artery involved by presumed territorial supply was accurate in 81%. DSE is a highly accurate tool for evaluating CAD, identifying both the patient with CAD and the location of disease.