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Biomedical subjects

B S Tan

Publications and source records attributed to B S Tan.

33 records · Page 2Linked to original sources
PubMed1999

Tissue microangiography using a simplified barium sulphate cadaver injection technique.

This study investigated the application of soft tissue X-ray imaging as a method of studying vascular anatomy in injected cadaveric specimens. The arterial system of the anatomical region of interest was perfused with a barium sulphate-gelatin suspension. After curing, the tissues were removed by meticulous dissection and examined using the soft tissue X-ray imaging system. This technique of microangiography was able to demonstrate the entire arterial system of the perfused specimen. This simplified technique shows great potential in the study of vascular anatomy of flaps.

Angiography↗
PubMed1999

Radiological placement of 211 central venous catheters: outcome and complications.

A prospective study of 211 central venous catheters consecutively placed in 186 patients under radiological guidance was conducted over an 18-month period. The majority (64%) of our patients were at risk for acute complications or failure. These risks included bleeding tendency, distorted anatomy, or previous complicated lines and failed "blind" percutaneous attempts. We employed the subtraction angiographic technique for venous mapping or ultrasound localisation to guide our initial puncture. The accumulated catheter experience was 15,295 days and the median catheter survival time was 166 days. The success rate was 100%. Our acute complications included 1 case of arterial puncture (0.5%), 2 pneumothoraces (1.0%), and 13 patients (6.1%) with haematoma or prolonged oozing at the puncture site. The calculated infection rate was 0.25 episodes per 100 catheter days at risk. These results are comparable to those reported in the literature. We conclude that central venous catheterisation using imaging guidance is accurate and safe, and should be the method of choice especially in high-risk patients.

Adolescent↗
PubMed1999

Outcome of tunnelled central venous haemodialysis catheters inserted by radiologists.

Radiologists have only recently been involved in the percutaneous placement of tunnelled central venous haemodialysis catheters. We report our initial experience with our first 60 catheters. All catheters were successfully inserted. Immediate complications encountered included puncture site haemorrhage in 3 patients (5%) and puncture of the left brachiocephalic vein in 1 patient (1.7%). These were managed conservatively without any clinical sequelae. About 80% of the catheters were uncomplicated and removed electively. Slightly more than 80% of the catheters were in place for more than 30 days. Infection and blocked catheters were the most common short-term complications. Ten catheters (17%) were infected resulting in premature removal of 9. There was 1 death from presumed line sepsis. Mean duration before the onset of infection was 53 days; the rate of infection was 0.28 episodes per 100 catheter days. Five catheters (8%) were blocked or had poor flow. The mean duration before the onset of blockage was 39 days and the rate of blockage was 0.14 episodes per 100 catheter days. A higher proportion of catheters inserted from the left encountered complications. In conclusion, percutaneous insertion of tunnelled haemodialysis catheters by radiologists is safe and effective. The right internal jugular vein should be the preferred access site. Precautions should be taken to avoid infectious complications given the high rate of catheter removal amongst infected catheters.

Catheters, Indwelling↗
PubMed1999

Clinics in diagnostic imaging (44). Testicular tumour with retroperitoneal lymphadenopathy and inferior vena cava thrombosis.

A 20-year-old Indian man presented with a two week history of non-specific abdominal pain. Abdominal ultrasonograpy incidentally detected a thrombus in the inferior vena cava (IVC). Computed tomography revealed the presence of extensive para-aortic lymph node disease as well as a filling defect in the IVC. Scrotal ultrasonography located a heterogeneous intra-testicular tumour in an otherwise palpably-normal testis. The extent of the IVC thrombus was evaluated by the use of magnetic resonance imaging. Inguinal orchidectomy was performed and histology revealed a non-seminomatous germ cell tumour. Combination chemotherapy led to complete resolution of lymph node disease and IVC thrombus. The patient remained well 9 months after diagnosis. The causes of IVC obstruction, role of imaging in investigating IVC obstruction and the management of tumour involvement of the IVC are discussed.

Adult↗
PubMed1997

Human herpesvirus-6 (HHV-6) DNA and virus-encoded antigen in oral lesions.

Archival oral tissues comprising 51 squamous cell carcinomas, 18 non-malignant lesions and 7 normal mucosa samples were investigated for human herpesvirus-6 (HHV-6)-encoded antigens and HHV-6 DNA. The virus-specific antigens were detected by an immunohistochemical method using monoclonal antibodies. Two further techniques used for HHV-6 DNA detection included the polymerase chain reaction (PCR) with virus-specific primers and in situ hybridization using digoxigenin-labelled oligonucleotides specific for HHV-6A and HHV-6B genotypes. A high proportion (79-80%) of the squamous cell carcinomas were positive for HHV-6 with the various detection methods. In cases of lichen planus and leukoplakia a high prevalence rate (67-100%) was noted with in situ hybridization and immunohistochemical techniques but a lower proportion (22-33%) was detected with the PCR method. All 7 normal tissues tested were negative for HHV-6. The HHV-6 variant B was found in 60% of the oral carcinoma tissues analysed. The study demonstrates the frequent presence of HHV-6 in neoplastic and non-malignant lesions of the oral cavity. While the role of HHV-6 in oral mucosal tissues remains to be determined, the in vitro tumorigenic potential of the virus suggests a possible role in the etiopathogenesis of oral lesions.

Antibodies, Monoclonal↗
PubMed1997

Palliation of inoperable esophageal carcinoma: a prospective randomized trial of laser therapy and stent placement.

PURPOSE: A prospective, randomized comparison of the result of endoscopic laser therapy and that of placement of self-expandable metallic endoprostheses was performed to determine which method provides the best palliation of dysphagia in patients with inoperable esophageal carcinoma. MATERIALS AND METHODS: Sixty patients participated in the study. Twenty-three were randomly assigned to undergo plastic-covered stent placement, 19 to undergo uncovered stent placement, and 18 to undergo laser therapy. The quality of swallowing was assessed with the dysphagia score, which ranged from 0 for normal swallowing to 4 for complete dysphagia. RESULTS: The mean improvement in dysphagia score was 2 and ranged from -1 to 3 in patients who underwent placement of plastic-covered stents, was 2 and ranged from 0 to 4 in those who underwent placement of uncovered stents, and was 1 and ranged from 0 to 2 in those who underwent laser therapy. Six of 23 (26%) plastic-covered stents migrated, whereas none of the uncovered stents did so (P < .02). Tumor ingrowth through uncovered stents occurred in five of 19 patients (26%). CONCLUSION: Placement of metallic esophageal endoprostheses is substantially better than endoscopic laser therapy for palliation of dysphagia in patients with inoperable esophageal carcinoma. Use of uncovered and plastic-covered metallic stents provides equal palliation in patients with dysphagia.

Adult↗
PubMed1997

Using uncovered metallic endoprostheses to treat recurrent benign esophageal strictures.

OBJECTIVE: The management of recurrent benign esophageal strictures is a difficult clinical problem, especially in patients who are not surgical candidates. We evaluated the role of uncovered metallic endoprostheses in four patients who had strictures that were resistant to repeated balloon dilatation. CONCLUSION: Our preliminary experience indicates that uncovered metallic endoprostheses can be effective in treating a select group of patients who have benign esophageal strictures and for whom multiple dilatations have failed. It is also important to note that epithelial hyperplasia can result in stenoses and recurrent dysphagia.

Aged↗
PubMed1997

The use of metallic stents in the palliation of inoperable oesophageal carcinoma.

Carcinoma of the oesophagus is the seventh most common malignancy worldwide. It is a disease with a poor prognosis; more than half of the patients present with surgically irresectable tumours. For such patients, palliative therapy is directed towards the relief of dysphagia. Expandable metallic stents have recently been developed for use in the oesophagus. These have the advantage of being introduced through small diameter delivery catheters. Once released, they can expand to as much as 25 mm in diameter, potentially allowing patients to consume a normal diet. The current designs of metallic stents include the Strecker stent, the Wallstent endoprosthesis, and the Gianturco-Rosch stent. The Strecker is an uncovered stent while the other two are covered on the outside of the stent with plastic to prevent tumour ingrowth. A review of the literature indicates that deployment of these stents is associated with a high technical success rate. Improvement in swallowing function is seen in 83% to 100% of these patients. The overall complication rates are low. However, covered stents are prone to migration while uncovered stents are vulnerable to tumour ingrowth. Further improvements in design promise to expand the role of these endoprostheses in the management of oesophageal carcinoma.

Deglutition Disorders↗
PubMed1996

Two cases of chronic recurrent multifocal osteomyelitis: radiological and scintigraphic findings.

Chronic recurrent multifocal osteomyelitis (CRMO) is an extremely rare condition, of uncertain aetiology. Since first described, in 1972, under 100 cases have been reported. It is being reported with increasing frequency, and many cases of this disease go unreported. It most commonly affects patients in childhood or adolescence. No infective agent has been identified, and antibiotics do not affect the course of the disease. We present the cases of two female children with this disorder, describe the radiological and scintigraphic findings and review the literature. Case 1 is the first reported case to our knowledge of CRMO presenting with cranial nerve palsies.

Bone and Bones↗
PubMed1995

The use of metallic stents in the treatment of malignant superior vena caval obstruction.

Superior vena caval obstruction due to malignancy is conventionally treated by radiotherapy and/or chemotherapy. In patients with unresolved or recurrent obstruction after treatment, expandable metallic stents can be percutaneously placed within the vena cava for relief of symptoms. In this series, metallic stents were successfully deployed in 11 consecutive patients with bronchial carcinoma. Gianturco Z stents were used in 10 patients and Strecker stents in one. There were 2 minor procedural complications of no sequelae. All patients had partial or full relief of symptoms after the procedure. On follow-up (mean 3.9 months), 9 patients had no recurrent symptoms up till the time of death or the present time. Two patients had recurrent obstruction, both within a week of the procedure. Based on our experience, percutaneous stenting was an effective means of palliation in this group of patients when other treatment modalities failed.

Equipment Design↗
PubMed1987

Glucocorticoid action on the growth and development of insects.

Cortisol increased growth and differentiation in the large milkweed insect (Oncopeltus fasciatus). The glucocorticoid significantly increased the growth of the insect as analyzed by wet and dry weights. Cortisol also stimulated the development of the insects over that of the controls during the six day bioassay.

Aldosterone↗
PubMedDate not supplied

Metallic endoprostheses for malignant tracheobronchial obstruction: initial experience.

PURPOSE: To assess the efficacy of the Wallstent endoprosthesis in malignant tracheobronchial obstruction. METHODS: Seven patients with irresectable carcinoma of the bronchus were treated with nine Wallstent endoprostheses. The procedures were performed under endoscopic and fluoroscopic guidance. Wallstent endoprostheses ranging from 8-16 mm in diameter and 26-49 mm in length were deployed after balloon dilatation of the strictures. RESULTS: All stents were successfully deployed in the desired positions. There was one procedural complication and one procedure related death. Three patients showed significant improvement in respiratory status after stenting. At a mean follow-up of 5.1 months, there has been no stent migration, fracture, or collapse. One patient had proximal tumor overgrowth that was treated with additional stent insertion. One patient died after a bout of massive hemoptysis 3 months poststenting and it was difficult to tell whether this was related to the endoprosthesis. CONCLUSION: The use of the Wallstent endoprosthesis in malignant tracheobronchial obstruction is technically feasible.

Aged↗