Biomedical subjects

T W Tan

Publications and source records attributed to T W Tan.

13 recordsLinked to original sources

PubMed1997

Cloning, characterization and expression of a cDNA clone encoding rabbit ubiquitin-conjugating enzyme, E2(32k).

A cDNA clone encoding rabbit E2(32k) was obtained by library screening and PCR. The cDNA contains an open reading frame coding for 238 amino acids which shows an overall identity of 81% to human CDC34, the cell cycle-related ubiquitin-conjugating enzyme. A 50% homology to yeast CDC34 within the conserved core domain was also observed. Northern blot analysis indicated that three transcripts existed in all six rabbit tissues examined but their expression levels varied over a wide range. The putative cDNA coding region was highly expressed in Escherichia coli as a his-tagged protein which was purified to homogeneity. The ability of this expressed protein to form a thiolester bond with ubiquitin showed that it was functionally active. The ability of this protein to catalyze the conjugation of ubiquitin to histone H2A and H2B was also examined.

Amino Acid Sequence↗

PubMed1996

Patient profile and survival in 270 computer tomography-staged patients with nasopharyngeal cancer treated at the Singapore General Hospital.

This is a report analysing the patient profile and survival results in 270 patients with nasopharyngeal carcinoma treated with radiation therapy between July 1987 and December 1988. The patients had a median age of 52.6 months, and a male-female ratio of 2.5:1. Ninety-four percent of patients were Chinese. The commonest presentation was that of a neck mass (found in approximately 65% of patients). Approximately two-thirds presented with disease more advanced than Ho's stage II. At a median follow-up of 52.6 months, the 5-year actuarial survival rate was 53% and the freedom from relapse rate was 57%. One hundred and seven patients died within the observation period. Of these, 46 patients had disease in the post nasal space, 41 in the neck and 60 in sites outside the head and neck.

Actuarial Analysis↗

PubMed1996

Localised nodal non-Hodgkin's lymphoma--a study of 42 cases treated by radiotherapy.

The records of 42 patients with stage I and II nodal non-Hodgkin's lymphoma treated by radiotherapy with and without chemotherapy were analysed with regards to clinical presentation, investigations, treatment, radiotherapy techniques and results. The 5-year overall survival rates for all, low grade, intermediate grade and high grade histology types are 69.5%, 100%, 64.4% and 46.9% respectively. The 5-year relapse-free survival rates of those treated by initial radiotherapy alone for all, low grade and intermediate-high grade histology types are 54.8%, 46.9% and 59.4% respectively.

Adolescent↗

PubMed1996

Testicular seminoma--the results of treatment by radiotherapy in Singapore.

A retrospective analysis was done of 49 patients treated for testicular seminoma over a 15-year period between January 1980 and April 1995 at the Department of Therapeutic Radiology, Singapore General Hospital. Their mean age was 39 years and their median period of follow-up was 67 months. Using the Royal Marsden Staging classification, 35 (71.4%) were stage I, 10 (20.4%) were stage II, I (2%) was stage III, and 3 (6.1%) were stage IV. Five (10.2%) arose in undescended testes. Thirty-six patients were treated with inguinal orchidectomy and postoperative radiotherapy to the para-aortic and ipsilateral iliac nodes. Eight had para-aortic and bilateral iliac irradiation, and 2 had ipsilateral pelvic, para-aortic, mediastinal and supraclavicular lymph node irradiation. Six of the patients had, in addition, irradiation of the inguinal-scrotal area. Nine received both chemotherapy as well as radiotherapy. The median dose of radiation given was 30.67 Gy and where a boost was required, the median total tumour dose was 35.75 Gy. The actuarial relapse-free survival at 10 years was 88.9% and the actuarial overall survival at 10 years was also 88.9%. Long-term treatment toxicities were uncommon.

Actuarial Analysis↗

PubMed1995

Delivering health information databases on World Wide Web at the National University of Singapore.

The National University of Singapore (NUS) is one of the first medical schools in Asia to exploit the use of the World Wide Web on the Internet for the delivery of health information databases. Its WWW server was established in 1993 by the NUS Biocomputing Research and User Support (BRUS) technology group in collaboration with the Computer Resource Planning committee of the Faculty of Medicine. As a result of the early recognition of the powerful platform on which health information services can be delivered worldwide, the NUS effort has been accredited with a number of Internet firsts in the area of health informatics. The following are some of the NUS achievements: NUS-NCI CancerNet on the Web. The NUS developed and implemented the first WWW version of the popular CancerNet database offered by the National Cancer Institute, NIH, USA. Health Info-Com Network Medical Newsletter. The NUS developed and implemented the first WWW version of the medical newsletter, MEDNEWS which is edited by Dr. David Dodell, USA. It is now mirrored by the University of Pennsylvania in the United States and De Montfort University, U.K. Poisons Information Database. This first WWW implementation of a database on known plant, snake and other animal toxins with directories of antivenoms, toxinologists and poisons control centers around the world is offered by the NUS Venom and Toxin Research Group. HistoNet. This is a large collection of histology specimens from the NUS Department of Anatomy. MEDISTAT. This is the first WWW implementation of a Health and Population Statistical Database which contains information for Singapore, selected Asian countries and aggregate data for world regions. The Singapore Biotechnology Database. This database features companies and organizations involved in biotechnology and related activities in Singapore. Efforts are continuing to offer more value-added health information databases on the NUS WWW server and to link the server with other top-class information centers worldwide. Our mission is to identify the National University of Singapore as a global health information hub on the Internet.

Computer Communication Networks↗

PubMed1994

The role of gastric muscle relaxation in cytoprotection induced by san-huang-xie-xin-tang in rats.

We examined the mechanism of the protective effect of San-huang-xie-xin-tang (SHXT), a traditional oriental drug, on the gastric mucosa. SHXT, given intraduodenally, inhibited the gastric secretion in pylorus-ligated rats. SHXT, given orally 30 min before the administration of aspirin, HCl-aspirin and ethanol, protected the gastric mucosa from these agent-induced gastric lesions, although it had no effect on the gastric lesions induced by indomethacin and water immersion stress. Oral administration of SHXT increased gastric contents (muscle relaxation) when they were measured 30 min after SHXT administration. SHXT also inhibited carbachol-contracted gastric muscle in vitro. Neither increased gastric contents nor inhibited ethanol lesions of SHXT were observed when these were tested 4 h after SHXT administration. Pretreatment with indomethacin which is a prostaglandin synthesis inhibitor, and N-ethylmaleimide which is a sulfhydryl blocker did not influence either the increased gastric contents or inhibited ethanol lesions of SHXT. These results indicate that gastric muscle relaxation plays an important role in the gastric protective mechanisms of SHXT, and the endogenous prostaglandins and the sulfhydryl compounds are not necessary for the action of SHXT.

Administration, Oral↗

PubMed1993

A hypertext-like approach to navigating through the GCG sequence analysis package.

Programs of the recently released Unix version of the Genetics Computing Group (GCG) sequence analysis package can now be accessed via a user-friendly hypertext-like navigation system, HYGCG. The resultant system organizes the diverse suite of programs into logical groups, and provides a guide and explanation of commands. In addition, for users unfamiliar with the Unix operating system, the program also provides a similar interface to commonly used Unix commands. Options for personal customization and expansion to accommodate GCG extensions and other software are also provided. This system should be useful especially to the inexperienced or infrequent user as context-sensitive on-line help is provided within this simple and consistent approach. Written in the C language and using the curses and termcap libraries, the system is easily portable to most Unix environments and has been made freely available via anonymous file transfer protocol (FTP) through the Internet global computer network. No modification of the GCG package is needed.

Sequence Analysis↗

PubMed1993

A general UNIX interface for biocomputing and network information retrieval software.

We describe a UNIX program, HYBROW, which can integrate without modification a wide range of UNIX biocomputing and network information retrieval software. HYBROW works in conjunction with a separate set of ASCII files containing embedded hypertext-like links. The program operates like a hypertext browser featuring five basic links: file link, execute-only link, execute-display link, directory-browse link and field-filling link. Useful features of the interface may be developed using combinations of these links with simple shell scripts and examples of these are briefly described. The system manager who supports biocomputing users should find the program easy to maintain, and useful in assisting new and infrequent users; it is also simple to incorporate new programs. Moreover, the individual user can customize the interface, create dynamic menus, hypertext a document, invoke shell scripts and new programs simply with a basic understanding of the UNIX operating system and any text editor. This program was written in C language and uses the UNIX curses and termcap libraries. It is freely available as a tar compressed file (by anonymous FTP from nuscc.nus.sg).

Biometry↗

PubMed1990

Antibody response of the ovine lymph node to experimental infection with an ovine abortion strain of Chlamydia psittaci.

After primary infection with Chlamydia psittaci in the draining area of the popliteal lymph node, viable organisms could be isolated from the efferent lymph only before the primary immune response developed. The lymph antibody response, as assayed by the complement fixation and immunofluorescence (IF) antibody tests, showed a rise in titre that peaked approximately 2 weeks after infection. Immunoblotting revealed that antibodies produced during this period were predominantly directed against the major outer membrane protein (MOMP). In secondary infection of convalescent sheep, an elevated IF antibody titre, already present in the lymph and blood, could not be boosted. Viable organisms could not be isolated from these sheep. Antibodies produced reacted to 12-14 bands in the immunoblot profile including the MOMP band. These potentially immunoprotective antigens, particularly MOMP, should be considered as useful candidates for an improved vaccine against ovine enzootic abortion, in further investigations.

Abortion, Veterinary↗

PubMed1990

Efficacy against ovine enzootic abortion of an experimental vaccine containing purified elementary bodies of Chlamydia psittaci.

A vaccine prepared from purified, inactivated elementary bodies of Chlamydia psittaci protected sheep against abortion after subcutaneous challenge with live chlamydiae. Immunoblot analysis of serum samples revealed a consistently dominant antibody response against the chlamydial major outer membrane protein in all vaccinated sheep. Reactions to other chlamydial antigens were also detected but were less pronounced or inconsistent. Serological responses detected by complement fixation were variable and did not correlate with immunity.

Abortion, Veterinary↗

PubMed1990

Protection of sheep against Chlamydia psittaci infection with a subcellular vaccine containing the major outer membrane protein.

An outer membrane (OM) preparation from elementary bodies (EBs) of Chlamydia psittaci (ovine abortion strain) was used to vaccinate pregnant ewes in a single subcutaneous dose and was found to achieve protection after subcutaneous challenge with infectious organisms. Inactivated purified EBs used as a single-dose vaccine also gave protection. The ratio of live to dead lambs was significantly higher in the vaccinated groups (16:1 and 15:1, respectively) than in the placebo group (8:9). Polyacrylamide gel electrophoresis and immunoblotting showed that a 40-kilodalton protein was the main protein constituent of the OM preparation, and this was positively identified as the major outer membrane protein by protein microsequencing. Electron microscopy revealed that fine particulate structures on the outermost surface of the EB were also present in the OM preparation. The findings suggest that the major outer membrane protein is an important immunoprotective determinant in ovine abortion vaccines.

Amino Acid Sequence↗

PubMed1989

Sequence analysis of the major outer membrane protein gene of an ovine abortion strain of Chlamydia psittaci.

The major outer membrane protein (MOMP) gene from an ovine abortion strain of Chlamydia psittaci (S26/3) has been cloned and sequenced. The gene shows the features of other chlamydial MOMPs but comparison with the previously reported sequence for the ovine abortion isolate A22/M has revealed substantial sequence divergence which is clustered into the same four intramolecular regions as the sequence variation found between C. trachomatis serovars. Subsequent restriction enzyme analysis of A22/M DNA has shown that it has an avian-type genomic profile and thus the comparison is between types rather than between strains.

Abortion, Veterinary↗

PubMed1989

The effects of vandellia cordifolia on renal functions and arterial blood pressure.

Vandellia cordifolia (COLSM) G. DON of Scrophulariaceae (V. cordifolia) is an annual wild herb indigenous to Taiwan. It can be found in plains, low altitudes, swampy places, and paddy fields. Taiwanese folk physicians use it in "nephritis, uremia, furnucle, carbuncle." The LD50 (95% confidence limit) of the crude extract of V. codifolia given by the oral route was more than 10 g/kg in rats. By the intraperitoneal route, it was 4.6 g/kg (4.35-4.93). The extraction rate was 16.6%. We studied its effects on renal functions and blood pressure and found that (1) it had diuretic effect on normal rats, (2) it decreased glomerular filtration rate and renal blood flow on normal kidneys in rabbits, (3) it had no effects on glomerular filtration rate and renal blood flow on glycerin-induced insufficient kidneys in rabbits, (4) it had diuretic effects on both normal and glycerin-induced insufficient kidneys in rabbits, (5) it could inhibit Na+ and K+ reabsorption on normal and glycerin-induced insufficient kidneys in rabbits, (6) it had hypertensive effect and this effect could be blocked by phenoxybenzamine. From the above facts, we conclude that V. cordifolia has diuretic effect and it may act on renal tubules to inhibit Na+ and K+ reabsorption.

Animals↗