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Biomedical subjects

A L Tan

Publications and source records attributed to A L Tan.

At least 19 recordsLinked to original sources
PubMed2006

The relationship between the extensor tendon enthesis and the nail in distal interphalangeal joint disease in psoriatic arthritis--a high-resolution MRI and histological study.

OBJECTIVES: Diffuse swelling of the distal interphalangeal (DIP) joint beyond the joint margin is a common feature of arthritis in psoriatic arthritis (PsA). The purpose of this study was to explore the microanatomical basis for the inflammation and nail disease in PsA using a combined high-resolution magnetic resonance imaging (MRI) and histological studies. METHODS: High-resolution MRIs of the DIP joint were obtained in 30 subjects [10 PsA, 10 osteoarthritis (OA) and 10 normal volunteers]. The relationship between the DIP joint capsule and associated tendon enthesis and the nail bed and root were evaluated. Histological studies to define the relationship between the normal cadaveric DIP joint capsule and the nail root were performed on the middle and ring fingers of 10 dissecting room cadavers. RESULTS: On MRI, the dorsal capsular enthesis was the epicentre of an inflammatory reaction. This extended to involve the soft tissues adjacent to the nail in 8 of 10 cases in PsA, but only 4 of 10 cases in OA where the inflammation is less intense and in none of the normal fingers. The DIP joint capsule was intimately linked with the nail complex on histology, with the dorsal, volar and lateral aspects of the nail bed being ensheathed in fibres extending from the entheses. CONCLUSION: The study suggests that the extended nature of the enthesis organ associated with the DIP joint may explain the diffuse nature of the inflammatory response around the nail in PsA. Therefore the nail is as much an integral part of the enthesis organ as it is of the skin, which has implications for a better understanding of the disease.

Adolescent↗
PubMed2006

Combined high-resolution magnetic resonance imaging and histological examination to explore the role of ligaments and tendons in the phenotypic expression of early hand osteoarthritis.

BACKGROUND: The pathogenesis of the early stages of hand osteoarthritis is poorly understood, but recent high-resolution magnetic resonance imaging (hrMRI) studies suggest that the joint ligaments have a major role in the phenotypic expression of the disease. OBJECTIVE: To combine hrMRI and cadaveric histological studies to better understand the mechanisms of damage, and especially the role of joint ligaments and tendons in disease expression. METHODS: hrMRI was carried out in the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints in 20 patients with osteoarthritis, with a disease duration < or = 12 months. Histological sections of the DIP and PIP joints were obtained from three dissecting-room specimens for comparative analysis. RESULTS: The collateral ligaments influenced the location of both hrMRI-determined bone oedema and bone erosion in early osteoarthritis. These changes were best understood in relation to the enthesis organ concept, whereby the interaction between ligament fibrocartilages leads to bone disease. Normal ligaments were commonly associated with microdamage at insertions corresponding to ligament thickening noted in early osteoarthritis. The ligaments also influenced the location of node formation in early osteoarthritis. The DIP extensor tendon insertions were associated with the development of a neoarticular surface. CONCLUSIONS: Small-joint collateral ligaments and tendons have a central role in the early stages of hand osteoarthritis, and determine the early expression of both the soft tissue and bony changes in disease.

Aged↗
PubMed2005

Epidemiology and clinical outcome of enterococcal bacteraemia in an acute care hospital.

OBJECTIVE: To determine the epidemiology and clinical outcome of enterococcal bacteraemia in an acute care hospital. MATERIALS AND METHODS: This is a retrospective study on enterococcal bacteraemia in an acute hospital from January 1999 to June 2001. Patients' clinical case notes were reviewed and their demographic, clinical and microbiological data were recorded. RESULTS: A total of 42 patients (25 males and 17 females) were included in the study, their mean age was 74.8+/-10.9 years. The majority of them had underlying diabetes mellitus and neurological disease. Seventeen patients required intensive care. Sources of enterococcal bacteraemia were identified in 21 cases (urinary tract, 13 patients; hepatobiliary, five; cardiovascular, two and soft tissues, one patient). Eighteen patients had prior invasive procedures. All the Enterococcus species isolated were vancomycin-susceptible; however, eight were ampicillin-resistant and 13 had high-level gentamicin resistance. Shock, disseminated intravascular coagulopathy, acute renal failure and cardiorespiratory arrest occurred in 42% of the cases. Antibiotics were prescribed appropriately in 31 patients and seven deaths were recorded. Of the 11 patients who received inappropriate therapy, six deaths were recorded. Inappropriate antibiotic therapy was associated with mortality. The mortality rate was 31%. Only one patient had a relapse of enterococcal bacteraemia from urinary tract infection secondary to underlying ureteric stricture. There were no vancomycin resistant cases. CONCLUSION: Urinary tract infection was the most common source of enterococcal bacteraemia. Appropriate antibiotics were essential in treating bacteraemia to reduce mortality. Vancomycin-resistant Enterococcus was not detected. The presence of comorbid conditions and invasive procedures in patients with enterococcal bacteraemia were found in 86 and 71% of patients, respectively.

Adult↗
PubMed2005

Infliximab in combination with methotrexate in active ankylosing spondylitis: a clinical and imaging study.

OBJECTIVE: To examine the efficacy and safety of infliximab combined with methotrexate compared with methotrexate alone in the treatment of ankylosing spondylitis (AS) using MRI and DXA to monitor its impact on bone. METHODS: In this single centre study 42 subjects with active AS were treated with methotrexate and were randomly assigned, in a ratio of 2:1, to receive five infusions of either 5 mg/kg infliximab or placebo over 30 weeks. The primary outcome was improvement in disease activity as shown by the BASDAI at week 30. MRI was used to assess the effect of treatments on sacroiliac and spinal enthesitis/osteitis and DXA to monitor bone mineral density. RESULTS: Both therapeutic agents were well tolerated with no dropouts due to adverse events. A significantly greater improvement in mean BASDAI score was seen in the infliximab arm at week 10 (p = 0.017) than in the placebo arm, but this was not maintained by week 30 (p = 0.195), 8 weeks after the last infusion, at which stage disease flares were reported by some subjects. MRI showed that the mean number of lesions resolving for each subject from week 0 to week 30 was significantly greater in the combination group than in the methotrexate monotherapy group (p = 0.016). CONCLUSIONS: Infliximab in combination with methotrexate was a safe and efficacious treatment in AS over 6 months and was associated with significant regression in enthesitis/osteitis as determined by MRI. However, disease flares were reported 8 weeks after the last infusion, indicating that addition of methotrexate failed to extend the infliximab dosing interval.

Absorptiometry, Photon↗
PubMed2004

Influence of the amyloid precursor protein locus on dementia in Down syndrome.

BACKGROUND: The amyloid precursor protein (APP) locus on chromosome 21 influences the development of Alzheimer disease. METHOD: The authors investigated the relationship between a tetranucleotide repeat on intron 7 of the APP gene and the age at onset of dementia in Down syndrome (DS). RESULTS: There was a 13-year difference in the age at onset of dementia in DS associated with the number of tetranucleotide repeat alleles in APP. CONCLUSION: APP is an important locus predicting the age at onset of dementia in people with Down syndrome.

Adult↗
PubMed2004

Efficacy of anakinra in active ankylosing spondylitis: a clinical and magnetic resonance imaging study.

OBJECTIVE: To determine the efficacy of anakinra, an interleukin 1 receptor antagonist in active ankylosing spondylitis (AS), and to investigate the effect of anakinra treatment on spinal enthesitis/osteitis using magnetic resonance imaging (MRI). METHODS: A 3 month open label study of anakinra (100 mg subcutaneous injection daily) was carried out in nine patients with active AS who had back pain and an increased acute phase response, and who had failed to respond to at least one non-steroidal anti-inflammatory drug. Clinical assessment included the Bath AS Functional Index (BASFI), Bath AS Disease Activity Index (BASDAI), and AS Quality of Life (ASQoL) before and after treatment. Fat suppressed MRI of the spine and sacroiliac joints was performed with a 1.5 T scanner at baseline and at 3 months to determine the effect of treatment on spinal enthesitis/osteitis. RESULTS: Significant improvement was found in the BASFI (median baseline 5.88, 3 months 3.63, p = 0.021), BASDAI (median baseline 5.63, 3 months 3.48, p = 0.028), ASQoL (median baseline 12, 3 months 8, p = 0.011) and laboratory measures reflecting inflammation, with C reactive protein (median baseline 31 mg/l, 3 months 17 mg/l, p = 0.036) and erythrocyte sedimentation rate (median baseline 19 mm/1st h, 3 months 15 mm/1st h, p = 0.008) also showing significant improvement. Six patients (67%) achieved the Assessments in AS (ASAS) Working Group criteria of 20% improvement. Of the 38 regions of enthesitis/osteitis determined by MRI at baseline, 23 (61%) either improved or regressed completely. CONCLUSIONS: This open label pilot study suggests that anakinra is effective in controlling the clinical manifestations of AS. The clinical response was reflected by an improvement in MRI determined spinal enthesitis/osteitis.

Adult↗
PubMed2003

Prospective randomized study of bacteraemia in diathermy and stapled haemorrhoidectomy.

BACKGROUND: The incidence and consequences of bacteraemia associated with diathermy and stapled haemorrhoidectomy have not been studied previously. METHODS: Two hundred and five healthy patients randomized to stapled haemorrhoidectomy or diathermy haemorrhoidectomy had perioperative blood cultures taken. The clinical sequelae of bacteraemia and complications of surgery were assessed prospectively. RESULTS: Six patients were excluded for protocol violations. Eleven (11 per cent) of 101 patients with stapled and five (5 per cent) of 98 who had diathermy haemorrhoidectomy had positive blood cultures for organisms after haemorrhoidectomy, predominantly anaerobes commonly found within the bacterial flora of the anorectum (P = 0.19). Transient postoperative pyrexia in several patients did not correlate with detected bacteraemia and settled spontaneously without treatment. There were no serious complications from either operative technique, and no clinical consequences from proven bacteraemia. CONCLUSION: Transient bacteraemia may complicate surgical haemorrhoidectomy but has no serious clinical consequences for healthy adults.

Adult↗
PubMed2002

Cryptococcus neoformans var. gattii meningitis in Singapore.

We describe here two cases of Cryptococcus neoformans var. gattii meningitis that occurred in Singapore. This variety of Cryptococcus neoformans differs from the more widely known C. n. var. neoformans in its ecology and epidemiology. Infections with this variety are still rare in Singapore.

Adult↗
PubMed2002

Microbiology of chronic suppurative otitis media in Singapore.

The objective of the study was to study the microflora and the antibiograms of patients with chronic suppurative otitis media (CSOM) in Singapore. Ninety patients with CSOM were prospectively studied. They had chronic ear discharge and had not received antibiotics for the previous five days. Swabs were taken, and cultured for bacteria. Antibiotic testing was done using modified Kirby Bauer disk diffusion method. In addition to the usual antibiotics, the three most common topically available antibiotics (chloramphenicol, gentamicin and neomycin) were tested. There were 135 positive cultures for organisms from the 90 patients. The most common causal organisms isolated were Pseudomonas aeruginosa (33.3%) and Staphylococcus aureus (33.3%) followed by coagulase negative Staphylococcus (21.1%). Fungi accounted for 8.8% of isolates while 6.6% were anaerobes. Of the three antibiotics commonly available as topical eardrops, gentamicin has the highest susceptibility rate (82.6%), followed by neomycin (67.8%) and chloramphenicol (62.8%).

Adolescent↗
PubMed2001

Shigella septicaemia in adults: report of two cases and mini-review.

INTRODUCTION: We report 2 cases of Shigella septicaemia in adult patients. CLINICAL PICTURE: Two 57-year-old women presented with non-bloody diarrhoea and fever. The first patient was an inmate of a long-term care facility who was schizophrenic and the second patient was a diabetic who recently travelled to Medan, Indonesia. Both patients were febrile, hypotensive and dehydrated. The first patient was neutropenic, thrombocytopenic and had acute renal failure. Blood cultures yielded Shigella flexneri and stool cultures gave negative results for both patients. TREATMENT: Rehydration and intravenous ceftriaxone were instituted. OUTCOME: The patients' symptoms and hypotension resolved. CONCLUSION: Appropriate antibiotics can decrease the severity and duration of Shigella septicaemia.

Ceftriaxone↗
PubMed2000

Non-steroidal anti-inflammatory drugs, Helicobacter pylori and bleeding gastric ulcer.

BACKGROUND: Helicobacter pylori infection and NSAID usage are considered to be independent risk factors for gastric ulcer (GU). Whether they interact to influence the risk of bleeding in GU is unclear. AIM: To determine the prevalence of H. pylori infection and NSAID ingestion in a group of patients with GU and determine their roles in bleeding and non-bleeding GU. METHODS AND RESULTS: From January 1993 to June 1996, a total of 217 GU patients (150 male, 67 female, median age 61 years, range 26-94) were eligible for the study. Eighty-five per cent were H. pylori-positive and 15% were H. pylori-negative. NSAID usage within 4 weeks prior to endoscopy was present in 30%, more in the H. pylori-negative than H. pylori-positive patients (59% vs. 25% P = 0.0002). Aspirin was most commonly used (43%). One hundred patients bled from GU (69 male, 31 female, mean age 67 years, range 26-94) and 117 did not (81 male, 36 female, mean age 57 years, range 28-86). Univariate logistic regression showed that advanced age (>/= 65 years) and NSAID usage carried an increased risk of bleeding GU (odds ratio 3.4 and 6.8, respectively) while H. pylori infection alone was not associated with additional risk (OR = 0.8). However, when three variables were considered jointly in a multiple logistic regression, the OR associated with H. pylori infection increased to 2.4, suggesting that in the presence of NSAIDs and advanced age, H. pylori also increases the risk of bleeding GU, indicating an interaction between the variables. CONCLUSION: NSAID usage and advanced age are risk factors for bleeding GU, whereas H. pylori infection by itself is not. In the presence of NSAIDs and advanced age, an increased risk of bleeding GU with H. pylori is observed, indicating the possibility of an interaction between these factors.

Adult↗
PubMed2000

Metronidazole-resistant Helicobacter pylori in an urban Asian population.

BACKGROUND: Helicobacter pylori eradication is the mainstay in the treatment of H. pylori-associated peptic ulcer disease. Metronidazole is an important component in most eradication regimens. However, the presence of metronidazole-resistant H. pylori adversely affects the efficacy of such regimens. We aimed to study the prevalence of metronidazole resistance in our population, and the factors associated with its presence. METHODS AND RESULTS: From September 1993 to September 1996, 459 H. pylori isolates were collected and analysed. The overall resistance rate was 62.7%. The rate was significantly higher among women compared with men (P < 0.05). When the results were analysed according to each year, there was a significant increase in the resistance rate from 50.5% in the first year to 72.7% in the third year (P = 0.0039). CONCLUSIONS: There was a significant rise in the prevalence of metronidazole resistance over a 3-year period. The presence of metronidazole resistance adversely affects the eradication rates of nitroimidazole-based regimens. Hence, in a population with a high prevalence of metronidazole resistance, the use of non-nitroimidazole-based therapy may be more efficacious. This information on resistance rates is important for the empirical choice of antibiotic against H. pylori in a population.

Adolescent↗
PubMed2000

Audit of a multidisciplinary vulvar clinic in a gynecologic hospital.

OBJECTIVE: To perform a five-year retrospective audit of all new patients referred to a tertiary vulvar referral service. STUDY DESIGN: A review was made of the records of all new clients who attended the vulvar clinic between 1993 and 1997. Information was entered into a database and analyzed. RESULTS: Four hundred seventeen women were seen in the study period. Their ages ranged from 8 to 94 years (mean, 48.5). The most common symptoms were pruritus (44.8%), soreness (28.6%) and irritation (24.2%). Striking features were the poorly defined and lengthy histories and multiple symptomatology. Biopsies were performed in 61% of cases. Histologic diagnoses included vulvar intraepithelial neoplasia (VIN), 18.5%; nonneoplastic epithelial disorders, 16.8%; and carcinoma, 8.1%. Clinical diagnoses included dermatitis in 10% and normal vulva in 7.7%. The remaining cases represented a wide variety of dermatologic, pain and gynecologic conditions. There was a 95% correlation between the clinical and histologic diagnosis of VIN and 87% in lichen sclerosus. In 64.7% of women, treatment resulted in an improved outcome, 13.7% reported no improvement, and 1.6% cases deteriorated during treatment; 19.9% were lost to follow-up. CONCLUSION: Provision of a multidisciplinary vulvar clinic in a tertiary setting provides an invaluable service for both primary and secondary clinical practitioners. The increasing demand for our services has created lengthy waiting times. The chronic nature of many vulvar diseases results in long-term follow-up of many women. Patient selection bias has developed as a consequence of the interests of the clinicians involved.

Adolescent↗
PubMed2000

Lung volume reduction surgery for the treatment of severe emphysema: a study in a single Canadian institution.

OBJECTIVE: To evaluate lung volume reduction surgery (LVRS) and its effectiveness in improving pulmonary function, exercise capacity and quality of life in a population of emphysema patients referred to and screened in a single centre. DESIGN: A prospective case series. SETTING: A Canadian tertiary care hospital. PATIENTS: Patients with severe emphysema, significant dyspnea and impaired exercise capacity interfering with quality of life. INTERVENTIONS: Bilateral LVRS was performed through a median sternotomy. MAIN OUTCOME MEASURES: Pulmonary function tests (preoperative forced expiratory volume in the first second [FEV1], residual volume [RV]), 6-minute walk (6 MW) distance, quality of life (Medical Outcomes Study 36-item short-form health survey) and degree of dyspnea (Medical Research Council of Great Britain dyspnea scale and the baseline and transitional dyspnea indices) were assessed before LVRS and at 6 and 12 months after. RESULTS: Fifty-seven patients were assessed for LVRS, of whom 10 were selected for surgery. Homogeneous distribution of disease was the most common reason for exclusion. Of the 10 patients operated upon, 1 died of acute cor pulmonale on the fourth postoperative day and 1 died of recurrent exacerbations of chronic obstructive pulmonary disease and chronic respiratory failure at 315 days postoperatively. In the surviving patients, the mean preoperative FEV1 increased from 0.70 L before surgery to 0.90 L at 1 year, with a mean relative increase of 33.4%. The mean RV decreased from 5.57 L to 4.10 L, with a mean relative decrease of 27.6%. The 6 MW distance increased from 302.7 m to 356.9 m at 1 year, with a mean relative increase of 21.6%. Quality of life and degree of dyspnea were improved significantly at 1 year after LVRS. Of the 5 patients on oxygen at home before surgery, 4 were able to reduce their requirements but not to discontinue oxygen. CONCLUSIONS: LVRS is an effective palliative treatment for dyspnea and poor exercise tolerance in highly selected patients. Although the duration of palliation is unknown, our results show that improvements in pulmonary function, exercise, quality of life and degree of dyspnea are preserved over the first year. Only a minority of the patients screened were eligible for surgery. The 2 deaths in our series emphasize the need for even further delineation of selection criteria.

Aged↗
PubMed2000

Recurrence of Helicobacter pylori infection and duodenal ulcer relapse, following successful eradication in an urban east Asian population.

We aimed to determine the rate of Helicobacter pylori (HP) recurrence and duodenal ulcer relapse in patients of a hospital in Singapore over a period of at least one year from the time of eradication. Ninety-six consecutive duodenal ulcer patients with biopsy-proven HP eradication and healed ulcer were seen at 3-month intervals, and follow-up endoscopy was performed when dyspepsia recurred, at the end of one year after eradication, or at the time of recall if the patient had been lost to follow-up. HP status was determined by antral and corpus biopsies and by antral cultures. Sixty-five had been given triple therapy, and 31 received dual therapy with omeprazole + amoxycillin or clarythromycin. Median time to follow-up endoscopy was 12 months. Six patients (6.25%) were positive for HP infection after eradication. Recurrence of HP infection was detected at 9 and 10 months after confirmation of HP eradication in two patients, and at between 13 and 20 months in the remaining four. Two of these had recurrent duodenal ulcer; all but one had erosive duodenitis. Two other patients had recurrent duodenal ulcer despite absence of HP reinfection; they admitted to taking low-dose aspirin. It was concluded that the recurrence of HP infection is low at the end of one year after successful eradication therapy in this urban East Asian population. Ulcer relapse occurred in 4.17% (4/96) of patients, and was associated with recurrent HP infection or NSAID exposure.

Adolescent↗
PubMed1999

Corneal topography of small-beam tracking excimer laser photorefractive keratectomy.

PURPOSE: To evaluate the topographic characteristic of photorefractive keratectomy (PRK) for low myopia performed with a small-beam (0.9 mm) tracking excimer laser. SETTING: Department of Ophthalmology, LSU Eye Center, Louisiana State University Medical Center School of Medicine in New Orleans, and the Refractive Surgery Center of the South at the Eye, Ear, Nose, & Throat Hospital, New Orleans, Louisiana, USA. METHODS: Sixty-seven eyes of 47 patients had PRK with a small-beam tracking laser. Of these, 49 eyes had data permitting evaluation of ablation centration; usable data for topographic analysis were available for 59 eyes preoperatively, 54 eyes at 1 month, 42 eyes at 3 months, and 25 eyes at 6 months, permitting measurement of various topographic parameters, including the cylinder (CYL), average corneal power (ACP), surface regularity index (SRI), surface asymmetry index (SAI), corneal eccentricity index (CEI), and coefficient of variation of corneal power (CVP). RESULTS: Preoperatively, all eyes were topographically normal. Postoperatively, no eye exhibited a "central island" by even the least-restrictive definition, and all eyes had best spectacle-corrected visual acuities (BSCVAs) of 20/20 or better at all follow-ups. Mean decentration of the ablations from the pupil centers was 0.42 mm +/- 0.28 (SD) (n = 49). There was no correlation between measured decentration and BSCVA (P = .46). The central cornea was flattened (decreased ACP; P < .001) and made oblate (decreased CEI; P < .001) as expected. There was no increase in SRI or SAI (irregular astigmatism) at 6 months compared with preoperative values (P = .91); however, CYL and CVP (varifocality) increased slightly (P = .04 and .02, respectively). CONCLUSION: The absence of significant regular or irregular astigmatism 6 months after PRK with the small-beam laser is an improvement over published results achieved with wide-beam lasers and is consistent with the excellent visual acuity results in this cohort.

Cornea↗