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S Y Tan

Publications and source records attributed to S Y Tan.

At least 91 records · Page 5Linked to original sources
PubMed1998

Bronchioloalveolar carcinoma with metastasis to the pituitary gland: a case report.

An unusual case of metastatic bronchioloalveolar carcinoma of the lung presented as a pituitary tumour in a young adult Chinese female, who subsequently died after having undergone trans-sphenoidal resection. Metastatic cancers of the pituitary are uncommon even in necropsy series and rarely give rise to clinical symptoms. This case draws attention to the fact that, although uncommon, pituitary metastases have been noted with increasing frequency and their distinction from primary pituitary tumours is often difficult. A metastatic pituitary tumour may be the initial presentation of an unknown primary malignancy, wherein the metastatic deposits may also be limited to the pituitary gland. Clinicians and pathologists alike should consider a metastatic lesion in the differential diagnosis of a non-functioning pituitary tumour.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1998

10 common medicolegal questions on HIV infection.

As the HIV pandemic continues, physicians will increasingly face both medical and legal questions when caring for these patients. Using a question and answer format, we provide in this paper, a guide to physicians in Hawaii on the medicolegal issues surrounding HIV infection.

Confidentiality↗
PubMed1997

Serial ultrasound-guided percutaneous liver biopsy in a partial hepatectomy porcine model: a new technique in the study of liver regeneration.

UNLABELLED: Studies on liver regeneration are often carried out on small animal models such as the rat. The use of large animal models however has many advantages. Repeated biopsies of the liver may be carried out and the animal can thus serve as its own control. Sequential changes in the regenerative response to various putative hepatotrophic factors can therefore be studied. Ultrasound-guided percutaneous biopsy (USGPB) of the liver, a technique widely used in clinical practice to obtain liver samples, offers a means for repeated liver biopsies. This study was carried out to validate the use of serial USGPB of the liver as a research technique in the study of liver regeneration in a porcine hepatectomy model. MATERIAL AND METHOD: Left hepatectomy was carried out in nine Yorkshire pigs (20-30 kg). Bromodeoxyuridine (BrdU) at 50 mg/ kg BW was administered daily for the first 5 days after surgery. USGPB was carried out 1 hr later using 16F biopsy needles in a Biopty device. Ultrasonography was carried out using an Acuson XP10 color doppler ultrasound machine. Immunoperoxidase staining of the biopsy specimens was performed using mouse monoclonal antibody to BrdU. Regenerating cells were identified and labeling indices constructed for each day after hepatectomy. All animals were sacrificed at the end of the study and postmortem was performed. RESULTS AND CONCLUSION: USGPB was successful at every attempt and no animal suffered complications following the procedure. Median cumulative labeling indices increased rapidly after hepatectomy and the steepest rise occurred between the third and fourth day after surgery when it increased from 2.25 to 3.40% before leveling off. These results are consistent with those obtained by other reported techniques. USGPB of the liver overcomes the need for repeated laparotomies to obtain biopsy samples in a large animal model and has no morbidity and mortality that could lead to animal wastage.

Animals↗
PubMed1997

Cognitive-behavioral therapy for clinical pain control: a 15-year update and its relationship to hypnosis.

Since Tan's (1982) review of cognitive and cognitive-behavioral methods for pain control was published 15 years ago, significant advances have been made in cognitive-behavioral therapy for pain. The scientific evidence for its efficacy for clinical pain attenuation is now much more substantial and is briefly reviewed. In particular, cognitive-behavioral therapy for chronic pain was recently listed as one of 25 empirically validated or supported psychological treatments available for various disorders. A number of emerging issues are further discussed in light of recent developments and research findings. The relationship of cognitive-behavioral therapy to hypnosis for pain control is briefly addressed, with suggestions for integrating hypnotic and cognitive-behavioral techniques.

Cognitive Behavioral Therapy↗
PubMed1996

Hereditary hepatic and systemic amyloidosis caused by a new deletion/insertion mutation in the apolipoprotein AI gene.

We report a Spanish family with autosomal-dominant non-neuropathic hereditary amyloidosis with a unique hepatic presentation and death from liver failure, usually by the sixth decade. The disease is caused by a previously unreported deletion/insertion mutation in exon 4 of the apolipoprotein AI (apoAI) gene encoding loss of residues 60-71 of normal mature apoAI and insertion at that position of two new residues, ValThr. Affected individuals are heterozygous for this mutation and have both normal apoAI and variant molecules bearing one extra positive charge, as predicted from the DNA sequence. The amyloid fibrils are composed exclusively of NH2-terminal fragments of the variant, ending mainly at positions corresponding to residues 83 and 92 in the mature wild-type sequence. Amyloid fibrils derived from the other three known amyloidogenic apoAI variants are also composed of similar NH2-terminal fragments. All known amyloidogenic apoAI variants carry one extra positive charge in this region, suggesting that it may be responsible for their enhanced amyloidogenicity. In addition to causing a new phenotype, this is the first deletion mutation to be described in association with hereditary amyloidosis and it significantly extends the value of the apoAI model for investigation of molecular mechanisms of amyloid fibrillogenesis.

Adult↗
PubMed1996

Sudden infant death in a tropical environment: Singapore's experience.

A total of 206 cases of sudden infant deaths examined at the Institute of Science and Forensic Medicine, Singapore, over a 5 year period (1989-93) were identified to assess the pattern of sudden death in this age group, which was subdivided into the neonatal and post-neonatal periods. A total of 34% (70) of infant deaths occurred in neonatal life and the remaining 66% (136) in the post-neonatal period; 90% of the neonatal deaths were natural, of which over half were due to congenital heart disease and complications of prematurity. Unnatural deaths in this period were uncommon, there being only seven such deaths. In the post-neonatal period, unnatural deaths constituted 25% of the total with trauma and aspiration heading the list. Natural deaths in the post-neonatal period are predominantly due to infections (34%) and a group of sudden natural deaths with minimal findings (31%). The latter group may arguably represent cases of Sudden Infant Death Syndrome (SIDS). The yearly incidence of this group in our study varied between 0.08 to 0.2 per 1000 live births, which is considerably lower than the incidence quoted for Western populations. The criteria for the classification and the impact of sudden infant deaths in Asian countries are discussed.

Cause of Death↗
PubMed1996

Transfection of L929 cells with complement subcomponent C1q B-chain antisense cDNA inhibits tumor necrosis factor-alpha binding to mediate cytotoxicity and nitric oxide generation.

The role of complement subcomponent C1q in the modulation of TNF-alpha binding to L929 cells to mediate cytotoxicity and nitric oxide (NO) generation was investigated. Transfection of L929 with murine C1q B-chain antisense plasmid cDNA rendered them markedly less susceptible to TNF-mediated cytotoxicity coincident with a decreased capacity for TNF-alpha binding and expression of cell surface C1q protein. The inhibitory effects of L929 transfection with C1q B-chain antisense were transiently expressed at 24 hr post-transfection with full recovery of cellular functions by 72 hr. Transfected L929 cells were fully reconstituted in their TNF-alpha binding and in their cytotoxic response following exposure to soluble C1q which was bound to their cell surface. Transfection with C1q B-chain antisense also significantly inhibited NO generation by L929 cells in response to stimulation by TNF-alpha, IFN-alpha/beta, and LPS. Taken together, these results indicate that endogenously synthesized C1q is prerequisite for binding of TNF-alpha to L929 cells to mediate cytotoxicity and NO generation.

Animals↗
PubMed1996

Molecular mechanisms of fibrillogenesis and the protective role of amyloid P component: two possible avenues for therapy.

Amyloid deposits regress when the supply of fibril precursor proteins is sufficiently reduced, indicating that amyloid fibrils are degradable in vivo. Serum amyloid P component (SAP), a universal constituent of amyloid deposits, efficiently protects amyloid fibrils from proteolysis in vitro, and may contribute to persistence of amyloid in vivo. Drugs that prevent binding of SAP to amyloid fibrils in vivo should therefore promote regression of amyloid and we are actively seeking such agents. A complementary strategy is identification of critical molecular processes in fibrillogenesis as targets for pharmacological intervention. All amyloidogenic variants of apolipoprotein AI contain an additional positive charge in the N-terminal fibrillogenic region of the protein. This is unlikely to be a coincidence and should be informative about amyloidogenesis by this protein. The two amyloidogenic variants of human lysozyme, caused by the first natural mutations found in its gene, provide a particularly powerful model system because both the crystal structure and folding pathways of wild-type lysozyme are so well characterized. The amyloidogenic variant lysozymes have similar 3D crystal structures to the wild type, but are notably less thermostable. They unfold on heating, lose enzymic activity, and aggregate to form amyloid fibrils in vitro.

Amyloid↗
PubMed1996

Long term effect of renal transplantation on dialysis-related amyloid deposits and symptomatology.

We report the five year outcome of nine patients with dialysis-related amyloid (DRA) who underwent successful renal transplantation (RT) and six patients who remained on hemodialysis (HD). Amyloid bone cysts, a radiologic feature of DRA, and scintigraphy with 123I-labeled serum amyloid P component (SAP), a specific technique for evaluating amyloid deposits in vivo, were monitored and compared with clinical features. In all HD patients there was clinical, scintigraphic and/or radiologic evidence that DRA progressed. In contrast, eight of the RT patients experienced profound early relief of DRA symptoms following transplantation that persisted throughout follow-up, despite the reduction or withdrawal of corticosteroids. Amyloid bone cysts improved in four patients and SAP scans demonstrated regression of articular amyloid in eight out of nine cases. The modest radiographic improvement suggests that amyloid is mobilized more slowly in bone cysts than elsewhere or that cystic bone is remodeled poorly. This is the first objective evidence that DRA regresses following renal transplantation, and suggests that this may contribute to the long-term relief of DRA symptoms in transplant recipients who discontinue corticosteroids.

Adult↗
PubMed1996

Primary localised amyloidosis of the orbit.

AIMS/BACKGROUND: Primary localised amyloidosis is rarely encountered in the orbit. The typical clinical and radiological appearances have not been clearly established, in particular the single site deposition of amyloid has never been proved. METHODS: Six cases were reviewed in detail and their clinical and radiological characteristics are described here. Four patients had scintigraphy with 123I serum amyloid P component and one patient had typing of the amyloid fibrils. RESULTS: All the patients had a firm mass in the upper orbit with a predilection for the region of the lacrimal gland. Computed tomography showed a homogeneous mass with thickening and irregularity of the adjacent bone and/or calcification within the mass. None was associated with systemic disease. Scintigraphy with 123I serum amyloid P component demonstrated that the amyloid was confined to the orbit. In one patient the amyloid fibrils were derived from an IgG4 heavy chain constant domain. The lesions were partially excised with subsequent clinical stability over 6 months to 18 years in all but one patient who had continued enlargement of the lesion. CONCLUSION: There is a characteristic clinical and radiological pattern for primary localised amyloidosis of the orbit. The disease process is truly local and not part of a systemic process. A majority respond to simple debulking with subsequent observation.

Adult↗
PubMed1996

How Hawaii's doctors feel about physician-assisted suicide and euthanasia: an overview.

We polled, by questionnaire, all doctors and medical trainees in Hawaii (n = 3,017) to determine their attitudes towards physician-assisted suicide, euthanasia and other end-of-life medical issues. One thousand and twenty-eight (34.1%) responded. Medical trainees did not differ significantly from practicing physicians. Only a minority of respondents (15.6%) were willing to assist a terminally-ill patient to commit suicide. An even smaller number (9.8) would perform active euthanasia. On the other hand, an overwhelming majority would withhold (97.6%) or withdraw (78.6%) life-support upon request. Most doctors (88.0%) were also willing to administer high doses of narcotics for pain relief, even if such therapy hastened death. About half the doctors felt that physician-assisted suicide and active euthanasia may be justified under some circumstances, although most were unwilling to personally carry out these acts. Catholic, Filipino and Hawaiian/Polynesian doctors were statistically less likely to approve of or perform physician-assisted suicide or active euthanasia.

Attitude of Health Personnel↗
PubMed1995

A novel variant of transthyretin, 59Thr-->Lys, associated with autosomal dominant cardiac amyloidosis in an Italian family.

BACKGROUND: Amyloidosis is a disorder of protein metabolism characterized by extracellular accumulation of abnormal protein fibrils. Different proteins form the fibrils in different forms of the disease, and the condition can be acquired or hereditary. Involvement of the heart is quite common, producing a serious and usually fatal cardiomyopathy. Cardiac amyloidosis is often diagnosed late, and cardiac biopsy together with proper histological examination is essential. Contrary to previous perceptions, there is much recent evidence of effective treatment for several different types of systemic and cardiac amyloidosis, including the most common hereditary form caused by mutations in the transthyretin gene. Chemical and genetic typing of amyloid is therefore of considerable clinical importance. METHODS AND RESULTS: Seven members in two generations of an Italian family presented with cardiac disease inherited as an autosomal dominant and were found to have systemic amyloidosis. Angina pectoris-like pain, an unusual feature in cardiac amyloidosis, was a prominent symptom, possibly related to partial obliteration of the distal coronary arteries by amyloid infiltration. There were also cases of sudden cardiac death. Peripheral and autonomic neuropathy, which are the usual features of hereditary amyloidosis, were present in only two cases, and a diagnosis of acquired, immunoglobulin light chain (AL type) amyloidosis was suspected in the index case before the family history emerged. In fact, the amyloid fibrils were composed of transthyretin, and the two affected individuals from whom DNA was available were both heterozygotes for a single base change in exon 3 of the transthyretin gene, encoding substitution of Lys for the wild-type Thr residue at position 59 in the mature protein. This mutation has not previously been reported. CONCLUSIONS: We have identified a novel mutation in the transthyretin gene encoding 59Thr-->Lys associated with autosomal dominant hereditary systemic amyloidosis in an Italian kindred in whom cardiac involvement was the major feature. This family illustrates the difficulty in diagnosis of cardiac amyloid, the variable clinical phenotype in hereditary amyloidosis even within a family, and the importance of precise fibril typing for correct management in this condition.

Amyloidosis↗