Search PubMed⌕ Search

Biomedical subjects

S H Tan

Publications and source records attributed to S H Tan.

At least 55 records · Page 3Linked to original sources
PubMed2001

Clinical utility of polymerase chain reaction in the detection of Mycobacterium tuberculosis in different types of cutaneous tuberculosis and tuberculids.

INTRODUCTION: The role of polymerase chain reaction (PCR) in the diagnosis of cutaneous tuberculosis in clinical practice has not been defined as no PCR assay has been tested in a large-scale clinical study. The objective of this study was to test the clinical utility of a PCR assay in the diagnosis of different types of cutaneous tuberculosis and tuberculids. MATERIALS AND METHODS: Analysis of archival biopsy specimens by a nested PCR assay targeting IS6110 of Mycobacterium tuberculosis (M. tb) DNA was performed in a tertiary-care skin hospital in Singapore. PCR results were compared with cultures and concordance with final diagnosis. PATIENTS AND SPECIMENS: One hundred and nineteen skin biopsies from 105 patients comprising 58 cases of confirmed or highly probable cutaneous tuberculosis, ranging from multibacillary infections to paucibacillary forms and 47 cases of possible tuberculids were analysed. Twenty-four subjects with non-tuberculous granulomas and normal skin controls were included. RESULTS: In 14 immunocompromised patients with multibacillary mycobacterial infections (AFB+ on biopsy), PCR was positive in 9 patients. Correlating PCR results with the final diagnosis, the PCR technique was 100% sensitive and specific in this group. In paucibacillary tuberculosis, PCR positivity rates were 55% for tuberculosis verrucosa cutis (38 cases) and 60% for lupus vulgaris (5 cases). When confirmed cases of tuberculosis were considered, the overall sensitivity was 73%. In 26 cases of erythema induratum, PCR was positive in 54% and correlated with a documented response to anti-tuberculous treatment in 80%. CONCLUSIONS: The use of PCR in the routine diagnostic panel for cutaneous tuberculosis should take into consideration the differential sensitivities for different clinical types. In the setting of an immunocompromised patient with AFB+ lesions, PCR has a definite role in rapid diagnosis and in differentiating atypical mycobacterial infection from tuberculosis. Where paucibacillary tuberculosis is suspected, clinical decision should not be based on PCR results alone. In erythema induratum, we found some correlation between PCR results and response to anti-tuberculous therapy.

Base Sequence↗
PubMed2001

A retrospective study of melanocytic naevi at the National Skin Centre.

INTRODUCTION: A retrospective study of melanocytic naevi was undertaken to assess the degree of clinico-pathological correlation and incidence of histological atypia. MATERIALS AND METHODS: The case records from January to March 1996 of all patients with histologically diagnosed melanocytic naevi at the National Skin Centre were analysed. RESULTS: Of the 240 lesions removed from 167 patients, the majority being women (111/167 patients), it was found that 55% (132/240) were correctly diagnosed. Fourteen per cent were mistaken for non-melanocytic lesions, namely skin tag, neurofibroma, syringoma cylindroma, epidermal naevus, naevus sebaceous and basal cell carcinoma. Most of the lesions were located on the cheeks and eyelids. Junctional naevi, followed by compound naevi were often missed. Histological dysplasia were seen in 7 naevi; 6 compound and 1 congenital naevi. There was a lack of clinico-pathological concordance in dysplastic naevi. CONCLUSIONS: The clinico-pathological concordance of melanocytic naevi was high, with low incidence of atypia on histology.

Adolescent↗
PubMed2001

Cardiovascular comorbidity and mortality in patients starting peritoneal dialysis: an American midwestern center experience.

End-stage renal disease (ESRD) patients frequently have multiple comorbidities, and cardiovascular disease remains the leading cause of death in these patients. The objectives of the present study were (1) to characterize the number and severity of cardiovascular comorbidities at the start of peritoneal dialysis (PD), and (2) to determine the impact of these comorbidities on mortality. We retrospectively studied all ESRD patients starting peritoneal dialysis at our center between 1990 and 1999. The baseline cardiovascular comorbid factors were categorized as ischemic heart disease, congestive heart failure, arrhythmia, peripheral vascular disease, and cerebrovascular disease. The severity of each factor was scored from 0 to 3. The number of comorbidities and the total cardiovascular comorbidity severity scores were determined for each patient. Cardiovascular deaths included those attributed to sudden death, cardiac disease, cerebrovascular disease, and complications of peripheral vascular disease. Of the 191 patients, 105 were men, and 105 (55%) had diabetes mellitus. The mean age was 60.8 +/- 13.3 years and the mean time on PD was 18.8 +/- 16.3 months. As the number of cardiovascular comorbidities increased, the proportion of patients who died of cardiovascular causes increased eighteen-fold. At each level of cardiovascular comorbidity, diabetic patients starting dialysis were younger, and their survival time was shorter as compared with non diabetic patients. Baseline comorbidity determination is important, as comorbidities are prognostic harbingers of eventual complications.

Cardiovascular Diseases↗
PubMed2001

Hypodermoclysis or subcutaneous infusion revisited.

AIM OF STUDY: To review the use of hypodermoclysis in a local Hospice. METHOD: A review of all hypodermoclysis carried out over a six-month period was conducted. Special attention was paid to the reason for starting and stopping the drip, duration of the drip, complications, the type and amount of solution infused. RESULTS: Fifty-one (19%) out of 266 patients received hypodermoclysis during their stay. This constituted 5.9% of total patient-days in the study period. Vomiting and drowsiness were the main reasons for the use of drip. The commonest reason for stopping the drip was patient demise. Complications seen were drip site redness (16%), extravasation (15%) and bleeding (2.5%) There was no overt clinical sepsis in any of the patients. CONCLUSION: Hypodermoclysis is an easy and convenient means of providing hydration. The availability of a standard protocol with clearer guidelines on its use will help to reduce procedure-related complications and promote wider adoption of the practice.

Fluid Therapy↗
PubMed2000

The genome structure of kyuri green mottle mosaic tobamovirus and its comparison with that of cucumber green mottle mosaic tobamovirus.

The genome of the Y strain of kyuri green mottle mosaic virus (KGMMV-Y) has been completely sequenced. Its genomic structure and sequence show it to be a typical tobamovirus, that is closest to, but distinct from, that of cucumber green mottle mosaic tobamovirus (CGMMV). The genomic sequence of KGMMV-Y was compared in detail with that of the SH strain of CGMMV. The sequences of their 5'- and 3'-untranslated regions were 74% and 63% identical. The amino acid sequences of the shorter and longer (read through) RNA replicase components, movement protein (MP) and coat protein (CP) were 58, 58. 60 and 46% identical, respectively. The KGMMV-Y genome sequence was also compared partly to that of another strain of KGMMV, KGMMV-C. The CP sequences of KGMMV-Y and KGMMV-C differed by 20 amino acid residues, suggesting that their relationship is more distant than the relationship between CGMMV-SH and CGMMV-W whose CP sequences are identical. The MPs of KGMMV-Y and KGMMV-C, however, differ only by one amino acid residue, although three amino acid substitutions are present in the MPs between CGMMV-SH and CGMMV-W. Two long stretches, one in the RNA replicase and the other in the MP, were highly conserved in KGMMV and CGMMV.

Amino Acid Sequence↗
PubMed2000

Epidemiology of cutaneous lupus erythematosus in a tertiary referral centre in Singapore.

The aim of this retrospective study was to investigate the epidemiology, yield of investigations and proportion of patients who develop systemic lupus erythematosus (SLE) among the subsets of cutaneous lupus erythematosus (LE) in the Singapore Asian population. One hundred and twenty-five patients were diagnosed with cutaneous LE on clinico-pathological correlation, of which 73 had discoid lupus erythematosus (DLE), eight had subacute cutaneous LE (SCLE), 22 had acute LE lesions and the remainder had other less common forms of cutaneous LE. Histology was consistent with LE in 94.4% and suggestive in 4.8%. Direct immunofluorescence was positive in 61% of DLE, 86% of SCLE and 80% of acute LE cases. Antinuclear antibody (ANA) was present in the majority of acute LE (85%) and SCLE (88%) but only in 25% of DLE. Eight patients (11%) presenting with DLE had definite SLE at first presentation and two (2.7%) subsequently several months later. Of these patients, six had only mucocutaneous and serological criteria but two had major organ involvement. Five SCLE patients (63%) fulfilled the criteria for SLE, including two with major organ involvement.

Academic Medical Centers↗
PubMed2000

Nuclear matrix attachment regions of human papillomavirus type 16 repress or activate the E6 promoter, depending on the physical state of the viral DNA.

Two nuclear matrix attachment regions (MARs) bracket a 550-bp segment of the long control region (LCR) containing the epithelial cell-specific enhancer and the E6 promoter of human papillomavirus type 16 (HPV-16). One of these MARs is located in the 5' third of the LCR (5'-LCR-MAR); the other lies within the E6 gene (E6-MAR). To study their function, we linked these MARs in various natural or artificial permutations to a chimeric gene consisting of the HPV-16 enhancer-promoter segment and a reporter gene. In transient transfections of HeLa cells, the presence of either of these two MARs strongly represses reporter gene expression. In contrast to this, but similar to the published behavior of cellular MARs, reporter gene expression is stimulated strongly by the E6-MAR and moderately by the 5'-LCR-MAR in stable transfectants of HeLa or C33A cells. To search for binding sites of soluble nuclear proteins which may be responsible for repression during transient transfections, we performed electrophoretic mobility shift assays (EMSAs) of overlapping oligonucleotides that represented all sequences of these two MARs. Both MARs contain multiple sites for two strongly binding proteins and weak binding sites for additional factors. The strongest complex, with at least five binding sites in each MAR, is generated by the CCAAT displacement factor (CDP)/Cut, as judged by biochemical purification, by EMSAs with competing oligonucleotides and with anti-CDP/Cut oligonucleotides, and by mutations. CDP/Cut, a repressor that is down-regulated during differentiation, apparently represses HPV-16 transcription in undifferentiated epithelials cells and in HeLa cells, which are rich in CDP/Cut. In analogy to poorly understood mechanisms acting on cellular MARs, activation after physical linkage to chromosomal DNA may result from competition between the nuclear matrix and CDP/Cut. Our observations show that cis-responsive elements that regulate the HPV-16 E6 promoter are tightly clustered over at least 1.3 kb and occur throughout the E6 gene. HPV-16 MARs are context dependent transcriptional enhancers, and activated expression of HPV-16 oncogenes dependent on chromosomal integration may positively select tumorigenic cells during the multistep etiology of cervical cancer.

Base Sequence↗
PubMed2000

Restoration of prehension with the double free muscle technique following complete avulsion of the brachial plexus. Indications and long-term results.

BACKGROUND: Recent interest in reconstruction of the upper limb following brachial plexus injuries has focused on the restoration of prehension following complete avulsion of the brachial plexus. METHODS: Double free muscle transfer was performed in patients who had complete avulsion of the brachial plexus. After initial exploration of the brachial plexus and (if possible) repair of the fifth cervical nerve root, the first free muscle, used to restore elbow flexion and finger extension, is transferred and reinnervated by the spinal accessory nerve. The second free muscle, transferred to restore finger flexion, is reinnervated by the fifth and sixth intercostal nerves. The motor branch of the triceps brachii is reinnervated by the third and fourth intercostal nerves to restore elbow extension. Hand sensibility is restored by suturing of the sensory rami of the intercostal nerves to the median nerve or the ulnar nerve component of the medial cord. Secondary reconstructive procedures, such as arthrodesis of the carpometacarpal joint of the thumb, shoulder arthrodesis, and tenolysis of the transferred muscle and the distal tendons, may be required to improve the functional outcome. RESULTS: The early results were evaluated in thirty-two patients who had had reconstruction with use of the double free muscle procedure. Twenty-six of these patients were followed for at least twenty-four months (mean duration, thirty-nine months) after the second free muscle transfer, and they were assessed with regard to the long-term outcome as well. Satisfactory (excellent or good) elbow flexion was restored in twenty-five (96 percent) of the twenty-six patients and satisfactory prehension (more than 30 degrees of total active motion of the fingers), in seventeen (65 percent). Fourteen patients (54 percent) could position the hand in space, negating simultaneous flexion of the elbow, while moving the fingers at least 30 degrees and could use the reconstructed hand for activities requiring the use of two hands, such as holding a bottle while opening a cap and lifting a heavy object. The results were analyzed to identify factors affecting the outcome. CONCLUSIONS: The double free muscle procedure can provide reliable and useful prehensile function for patients with complete avulsion of the brachial plexus.

Accessory Nerve↗
PubMed2000

Tetracycline and nicotinamide for the treatment of bullous pemphigoid: our experience in Singapore.

AIM OF STUDY: To study the efficacy of tetracycline (or doxycycline) and nicotinamide in the treatment of less extensive bullous pemphigoid. METHODS: An open trial of 11 patients with bullous pemphigoid. Treatment was initiated with tetracycline 1.5-2 g/day and nicotinamide 1.5-2 g/day and gradually tapered down. Doxycycline was substituted for tetracycline in patients who could not tolerate tetracycline due to gastrointestinal side effects or headache. RESULTS: 6 out of 11 patients achieved complete response (> 90% decrease in lesions) while another 2 had partial response (50-90% decrease in lesions). CONCLUSION: Tetracycline/doxycycline and nicotinamide is a useful alternative treatment for localized bullous pemphigoid, especially in those whose concurrent medical illnesses preclude the use of systemic corticosteroids.

Aged↗
PubMed2000

Protein nutrition status of adult patients starting chronic ambulatory peritoneal dialysis.

Malnutrition is an important determinant of outcome in patients on dialysis. Its cause is multifactorial and its detection is important when patients embark on dialysis. In this study, we used various indices to assess the prevalence of malnutrition as reflected in protein intake, anthropometric effect, and serum protein level. To avoid the effect that dialysis has on malnutrition, we studied 37 patients who had just started continuous ambulatory peritoneal dialysis (CAPD). Of these new patients, 42% had a residual urea clearance below 1.0 mL/min. In 51% of the patients, serum albumin level was below 33 g/L; in 14%, body mass index was below 19; and in 39%, dietary protein intake was below 0.8 g per kilogram of body weight per day. A total of 76% of our patients had at least one of these three indices. In 8% of the patients, lean body mass was below 60%. We conclude that protein malnutrition is a significant problem in our patients starting CAPD. Dialysis-dependent factors were not implicated, as the patients were studied at the start of dialysis. Low intake of protein was a major problem and may have contributed significantly to malnutrition. The low residual urea clearance implied that dialysis was started relatively late and may have contributed to the low protein intake.

Body Mass Index↗
PubMed2000

A case report of erythema induratum of Bazin's disease.

INTRODUCTION: Erythema induratum remains one of the rarely encountered tuberculid although tuberculosis is known to be endemic in the developing countries. We report a case of erythema induratum recently encountered in our centre. CLINICAL FEATURE: Clinically, erythema induratum typically manifests as ulcerative and indurated lesions on the lower limbs, especially the calves. TREATMENT OUTCOME: The patient responded well to a course of anti-tuberculous therapy with marked resolution of the lesions, suggesting the aetiological role of Mycobacterium tuberculosis in this condition. CONCLUSION: A short review of the distinguishing features of erythema induratum, the associated classical histological spectrum and the usefulness of polymerase chain reaction in the diagnosis of erythema induratum is given. A search for active foci of tuberculosis is advocated in all cases.

Antitubercular Agents↗
PubMed1999

Cutaneous Rosai-Dorfman disease presenting as pustular and acneiform lesions.

We report 2 cases of cutaneous Rosai-Dorfman disease (CRD) presenting with pustular and acneiform lesions. To our knowledge, these are the first reports of CRD presenting in this pattern. One patient had spontaneous resolution of the lesions, whereas the other was treated with cryotherapy with clinical improvement. We present a review of the literature regarding CRD and highlight the benign nature of this condition.

Acneiform Eruptions↗
PubMed1999

Hypergammaglobulinaemic purpura presenting as reticulate purpura.

Hypergammaglobulinaemic purpura, first described by Waldenstrom, is a rare skin disease. The essential features are the presence of purpura with polyclonal hypergammaglobulinaemia. We describe a case of hypergammaglobulinaemic purpura occurring in a Chinese man with reticulate purpura and haemorrhagic blisters.

Aged↗
PubMed1999

Detection of Mycobacterium tuberculosis DNA using polymerase chain reaction in cutaneous tuberculosis and tuberculids.

BACKGROUND: The objective of this study was to explore the role of the polymerase chain reaction (PCR) fo the detection of Mycobacterium tuberculosis DNA as a diagnostic aid in cutaneous tuberculosis using routinely processed skin biopsy specimens. METHODS AND RESULTS: A wide range of clinical specimens representing different forms of cutaneous tuberculosis and so-called tuberculids were studied. A sensitive and specific PCR assay targeting the sequence IS6110 of Mycobacterium tuberculosis complex was used. The specimens were categorized as follows. 1 Acid-fast bacilli (AFB) positive on biopsy (nine specimens from seven patients who were immunocompromised). PCR was positive in five specimens. Of these, one specimen was culture positive and three specimens were culture negative. 2 AFB negative on biopsy: (a) tuberculosis verrucosa cutis (23 specimens); (b) lupus vulgaris (three specimens); (c) cutaneous tuberculosis clinically suspected (six specimens). PCR was negative in all specimens. 3 Tuberculids.' (a) erythema induratum/nodular vasculitis (20 specimens); (b) papulonecrotic tuberculid (two specimens); (c) erythema nodosum (20 specimens). PCR was negative in all specimens. CONCLUSIONS: The role of PCR in clinical dermatologic practice, at this stage, may be in differentiating between cutaneous tuberculosis and atypical mycobacterial infections in the context of an immunocompromised patient where AFB can be demonstrated on biopsy and cultures may be negative. In this clinical situation, PCR allows the prompt diagnosis and early institution of appropriate therapy. We have not found PCR to be a useful complement to the clinical and histologic diagnosis of "paucibacillary" forms of cutaneous tuberculosis.

Adult↗
PubMed1998

The treatment of unrelated disorders in patients with chronic medical diseases.

BACKGROUND: Patients can have several illnesses concurrently, yet some of these diseases may be neglected if one problem consumes attention. We conducted a population-based analysis in Ontario, Canada - where universal health insurance is provided - to determine whether unrelated disorders are less likely to be treated in patients with chronic diseases. METHODS: We studied the 1,344,145 residents of Ontario in 1995 who were 65 or older and eligible to receive prescription medications free of charge as part of the Ontario Drug Benefit program. Patients with diabetes mellitus were identified by prescriptions for insulin, pulmonary emphysema by prescriptions for ipratropium bromide, and psychotic syndromes by prescriptions for haloperidol. For each chronic disease, we selected an unrelated treatment: estrogen-replacement therapy for patients with diabetes mellitus, lipid-lowering medications for those with pulmonary emphysema, and medical treatment of arthritis for those with psychotic syndromes. RESULTS: The 30,669 patients with diabetes mellitus were less likely to receive estrogen-replacement therapy than the other subjects in the study (2.4 percent vs. 5.9 percent, P<0.001). The disease was associated with a 60 percent reduction in the odds of estrogen treatment (odds ratio, 0.40; 95 percent confidence interval, 0.37 to 0.43). Findings were similar for the 56,779 patients with pulmonary emphysema, who were less likely to receive lipid-lowering medications (odds ratio, 0.69; 95 percent confidence interval, 0.67 to 0.72; P<0.001), and the 17,336 patients with psychotic syndromes, who were less likely to receive medical treatments for arthritis (odds ratio, 0.59; 95 percent confidence interval, 0.57 to 0.62; P<0.001). CONCLUSIONS: In patients 65 or older who have chronic medical diseases and who receive prescription medications free of charge, unrelated disorders are undertreated. Clinicians caring for patients with chronic diseases should remain alert to other disorders and minimize the number of missed opportunities for treating them.

Aged↗
PubMed1998

Nuclear matrix attachment regions of human papillomavirus type 16 point toward conservation of these genomic elements in all genital papillomaviruses.

The gene functions, transcriptional regulation, and genome replication of human papillomaviruses (HPVs) have been extensively studied. Thus far, however, there has been little research on the organization of HPV genomes in the nuclei of infected cells. As a first step to understand how chromatin and suprachromatin structures may modulate the life cycles of these viruses, we have identified and mapped interactions of HPV DNAs with the nuclear matrix. The endogenous genomes of HPV type 16 (HPV-16) which are present in SiHa, HPKI, and HPKII cells, adhere in vivo to the nuclear matrixes of these cell lines. A tight association with the nuclear matrix in vivo may be common to all genital HPV types, as the genomes of HPV-11, HPV-16, HPV-18, and HPV-33 showed high affinity in vitro to preparations of the nuclear matrix of C33A cells, as did the well-known nuclear matrix attachment region (MAR) of the cellular beta interferon gene. Affinity to the nuclear matrix is not evenly spread over the HPV-16 genome. Five genomic segments have strong MAR properties, while the other parts of the genome have low or no affinity. Some of the five MARs correlate with known cis-responsive elements: a strong MAR lies in the 5' segment of the long control region (LCR), and another one lies in the E6 gene, flanking the HPV enhancer, the replication origin, and the E6 promoter. The strongest MAR coincides with the E5 gene and the early-late intergenic region. Weak MAR activity is present in the E1 and E2 genes and in the 3' part of L2. The in vitro map of MAR activity appears to reflect MAR properties in vivo, as we found for two selected fragments with and without MAR activity. As is typical for many MARs, the two segments with highest affinity, namely, the 5' LCR and the early-late intergenic region, have an extraordinarily high A-T content (up to 85%). It is likely that these MARs have specific functions in the viral life cycle, as MARs predicted by nucleotide sequence analysis, patterns of A-T content, transcription factor YY1 binding sites, and likely topoisomerase II cleavage sites are conserved in similar positions throughout all genital HPVs.

Adenine↗