Search PubMed⌕ Search

Biomedical subjects

J Lim

Publications and source records attributed to J Lim.

At least 55 records · Page 3Linked to original sources
PubMed2003

A toolbox for intensity modulated radiation therapy optimization.

We have designed a toolbox that provides an environment for testing radiotherapy optimization techniques, objective functions, and constraints. A set of three-dimensional (3D) pencil beam dose distributions have been computed for a cylindrical phantom. The 6 MV pencil beams were computed using a superposition-based dose engine commissioned for an Elekta SL20 linear accelerator. Due to the cylindrical symmetry of the phantom, the pencil beam dose distributions for any arbitrary beam angle can be determined by simply rotating the pencil beam data sets. Thus, the full accuracy is maintained without the need for additional dose calculations or large data storage requirements. In addition to the pencil beam data sets, tools are included for (1) rotating the pencil beams, (2) calculating the beam's eye view, (3) drawing structures, (4) writing the pencil beam dose data out to the optimizer, and (5) visualizing the optimized results. The pencil beam data sets and the corresponding tools are available for download at http://medschool.umaryland.edu/departments/radiationoncology/pencilbeam/. With this toolbox, researchers will have the ability to rapidly test new optimization techniques and formulations for intensity modulated radiation therapy and 3D conformal radiotherapy.

Algorithms↗
PubMed2002

Surgical emphysema over the pelvis: an unusual physical sign found on primary survey.

Open fractures of the pelvis are associated with high energy trauma and present a challenge to successful management and sometimes, early and correct diagnosis. These patients require more aggressive blood resuscitation particularly in the first 24 hours, repeated wound care operations, and often require a diverting colostomy. Usually these pelvic fractures can be distinguished from closed pelvic fractures by an open wound or lacerations of the vagina and rectum. Occasionally, however, the wounds associated with these fractures may remain undetected and the severity of the injury underestimated until complications develop. The authors believe this to be the first report of subcutaneous surgical emphysema associated with an open pelvic fracture.

Adult↗
PubMed2002

Ambulatory paediatrics: does it work?

To determine whether a paediatric ambulatory assessment service is an effective and acceptable replacement for an inpatient unit. Analysis of hospital paediatric medical admissions. Postal questionnaire survey of local general practitioners. Telephone survey of parents of children who had attended the ambulatory service. Rural General Hospital in Northern Ireland. General practitioners. Parents of children referred to assessment service. Number of paediatric medical hospital admissions from the local area before and after the introduction of an ambulatory assessment service. General practitioner satisfaction levels. Parental satisfaction levels. Since the introduction of the new service in April 1996 there has been a marked progressive reduction in paediatric medical hospital admissions from the local area. By the third year of operation of the ambulatory service (1998/99), a 47% reduction in admissions was recorded, compared to the 1995/96 baseline year. The response rate to the general practitioner questionnaire was 65% (37 of 57) of whom most (31, 84%) found the service beneficial. Of the 37 respondents, 31 had referred patients to the service. The majority of these general practitioners (30, 97%) reported that the service was easy to access, and the same proportion felt that requests for consultation were met promptly. Most felt that feedback was appropriate (29, 94%). A telephone survey of 50 parents showed that most were either very satisfied (38, 76%), or satisfied (11, 22%) with the service. Most parents (41, 82%) felt their child had benefited by not being admitted to hospital. Most (46, 92%) felt they had received adequate information regarding their child's illness. A paediatric ambulatory assessment unit can reduce the number of children admitted to hospital and meet the needs of children, their families and general practitioners.

Ambulatory Care↗
PubMed2002

The mastectomy clinical pathway: what has it achieved?

INTRODUCTION: The mastectomy clinical pathway was developed to optimise the clinical care and cost management of breast cancer patients. The aim of this study was to prospectively assess the effect of the mastectomy pathway at the National University Hospital, Singapore over a 7-month period. MATERIALS AND METHODS: A prospective study was carried out on all breast cancer patients admitted for elective mastectomy between March and October 2001. As surrogates of optimised cost and care management, the length of stay and hospital costs, as well as the incidence of complications and unscheduled readmissions, were analysed. Non-pathway mastectomy patients treated from March to October 2000 were used as controls. A total of 83 patients who underwent mastectomy formed the pathway group, while 69 non-pathway patients acted as controls. RESULTS: Compared to controls, the mean length of hospital stay decreased significantly from 4.91 days to 4.10 days (P = 0.018) and the mean cost per case decreased significantly from $5,050 to $4,406 (P = 0.014) for those in the pathway group. There were no significant differences in the complications and unscheduled hospital readmission rates between the two groups (P > 0.05). CONCLUSION: The implementation of mastectomy clinical pathway has improved consistency in patient's treatment, the quality of patient outcome, and has reduced the costs of care and length of hospital stay. In addition, variance analysis of the mastectomy pathway has shown to be valuable for problem identification to improve patient care.

Adult↗
PubMed2002

A model for decentralised grey wastewater treatment system in Singapore public housing.

Global concerns over the sustainable use of natural resources provided the impetus for research into water reclamation from wastewater within the Singapore context. The objective of the research is to study and develop a water infrastructure system as an integral element of architecture and the urbanscape, thereby reducing the need for the large area requirements associated with centralised treatment plants. The decentralised plants were considered so as to break up the large contiguous plot of land otherwise needed, into smaller integrated fragments, which can be incorporated within the housing scheme. This liberated more usable space on the ground plane of the urban housing master plan, enabling water-edge and waterscape relationships within both the private and public domains of varying scale.

Facility Design and Construction↗
PubMed2002

A preliminary study of the utility of combined cardiac markers in the evaluation of patients presenting early with suspected acute coronary syndrome.

OBJECTIVE: The aim of the study was to investigate and compare the usefulness and accuracy of various cardiac markers [troponin I, creatine kinase MB (CKMB) mass, creatine kinase (CK), CKMB activity] to aid early diagnosis of myocardial infarction. We also examined the ability of the various cardiac markers to prognosticate future adverse cardiac events. MATERIALS AND METHODS: Patients admitted within 8 hours of maximal chest pain suggestive of acute coronary syndrome with non-diagnostic electrocardiograms were recruited. Blood samples were obtained on admission to the wards and repeated 4 hours later. These results were later correlated to the final hospital discharge diagnosis. RESULTS: The 37 patients in the study were a high-risk population with over 50% presenting with a Thrombolysis in Myocardial Infarction (TIMI) risk score of greater or equal to 3. Myoglobin was the most sensitive marker (100% sensitivity) in early prediction of patients who were subsequently diagnosed to have a myocardial infarction. Patients with an elevated troponin I level but normal CK and myoglobin levels had a significantly higher risk of developing a major adverse clinical event (MACE) within 3 months of the initial presentation. CONCLUSION: Myoglobin is the most sensitive marker when compared to CK, CKMB and troponin I for diagnosing patients presenting early with chest pain and a non-diagnostic electrocardiogram and who subsequently develop either a ST-elevation myocardial infarction or non-ST elevation myocardial infarction. Patients with an elevated troponin I level but normal CK and myoglobin levels are at higher risk of an adverse clinical event.

Adult↗
PubMed2001

Hemifacial microsomia: progress in understanding the genetic basis of a complex malformation syndrome.

Hemifacial microsomia (HFM) is a common birth defect involving first and second branchial arch derivatives. The phenotype is extremely variable. In addition to craniofacial anomalies there may be cardiac, vertebral and central nervous system defects. The majority of cases are sporadic, but there is substantial evidence for genetic involvement in this condition, including rare familial cases that exhibit autosomal dominant inheritance. As an approach towards identifying molecular pathways involved in ear and facial development, we have ascertained both familial and sporadic cases of HFM. A genome wide search for linkage in two families with features of HFM was performed to identify the disease loci. In one family data were highly suggestive of linkage to a region of approximately 10.7 cM on chromosome 14q32, with a maximum multipoint lod score of 3.00 between microsatellite markers D14S987 and D14S65. This locus harbours the Goosecoid gene, an excellent candidate for HFM based on mouse expression and phenotype data. Coding region mutations were sought in the familial cases and in 120 sporadic cases, and gross rearrangements of the gene were excluded by Southern blotting. Evidence for genetic heterogeneity is provided by the second family, in which linkage was excluded from this region.

Abnormalities, Multiple↗
PubMed2001

A genetic analysis of the cytological region 46C-F containing the Drosophila melanogaster homolog of the jun proto-oncogene.

The cytogenetic region 46C-F on the right arm of Drosophila chromosome 2, which contains the homolog of the human jun proto-oncogene, has been genetically mapped and characterized. This project led to the identification and characterization of a Jra (jun-related antigen) mutation, which has been described in detail elsewhere. Three mutagens, EMS, DEB and gamma-rays, were used to isolate 126 lethal lines for this interval. Complementation analysis of the 126 lethal lines identified 29 lethal complementation groups in the region; nine of which have now been correlated with known genes or phenotypes. The region has been subdivided into ten intervals using various small deletions, seven intervals in 46C/D and three intervals in 46E/F. Sixteen P-element lines have been mapped to this interval and are allelic to eight of our complementation groups. The remaining unidentified complementation groups have been analyzed for critical phase, which is when the first observable defect arises and/or when death occurs. There are twelve embryonic lethal groups and seven larval lethal groups. Three lines show visible abnormalities in gut and tracheal development prior to death.

Animals↗
PubMed2001

Conversion of a peroxiredoxin into a disulfide reductase by a triplet repeat expansion.

Pathways for the reduction of protein disulfide bonds are found in all organisms and are required for the reductive recycling of certain enzymes including the essential protein ribonucleotide reductase. An Escherichia coli strain that lacks both thioredoxin reductase and glutathione reductase grows extremely poorly. Here, we show that a mutation occurring at high frequencies in the gene ahpC, encoding a peroxiredoxin, restores normal growth to this strain. This mutation is the result of a reversible expansion of a triplet nucleotide repeat sequence, leading to the addition of one amino acid that converts the AhpC protein from a peroxidase to a disulfide reductase. The ready mutational interconversion between the two activities could provide an evolutionary advantage to E. coli.

Amino Acid Sequence↗
PubMed2001

Intraoperative single-shot "3-in-1" femoral nerve block with ropivacaine 0.25%, ropivacaine 0.5% or bupivacaine 0.25% provides comparable 48-hr analgesia after unilateral total knee replacement.

PURPOSE: To compare analgesia after intraoperative single shot "3-in-1" femoral nerve block (FNB) in combination with general anesthesia using ropivacaine 0.25%, ropivacaine 0.5% with bupivacaine 0.25% for total knee replacement (TKR). METHODS: We performed a randomized, double-blind study in 48 patients for elective TKR under general anesthesia. Patients were randomized to one of four groups (C: sham block, R1: "3-in-1" FNB using 30 mL of ropivacaine 0.25%, R2: "3-in-1" FNB using 30 mL of ropivacaine 0.5%, B: "3-in-1" FNB using 30 mL of bupivacaine 0.25%). Verbal pain score (VPS) both at rest and movement were assessed for 48 hr after TKR (0=none; 1=mild; 2=moderate; 3=severe). Total morphine consumption and its associated side effects, duration of hospitalization after operation were also compared. RESULTS: There were no differences in patients' physical characteristics, intraoperative morphine usage, operation time, tourniquet time or length of hospitalization between the four groups. When compared with group C, the VPS was significantly lower in groups R1, R2 and B at one, four, eight, 24 and 48 hr after TKR (P <0.05). The morphine requirement of groups R1, R2 and B were also significantly lower when comparing with group C up to 48 hr postoperatively (P <0.05). There were no significant differences in VPS and postoperative morphine requirement at any time between groups R1, R2 and B. CONCLUSION: "3-in-1" FNB with ropivacaine provided analgesia that was clinically comparable to that of bupivacaine up to 48 hr after TKR. Increasing the concentration of ropivacaine from 0.25% to 0.5% failed to improve the postoperative analgesia of "3-in-1" FNB.

Adult↗
PubMed2001

Postantibiotic effects and postantibiotic sub-MIC effects of erythromycin, roxithromycin, tilmicosin, and tylosin on Pasteurella multocida.

When intermittent dosing is used during treatment, the concentrations of antibiotics fluctuate and subinhibitory concentrations may occur between doses. Postantibiotic effects (PAEs) and postantibiotic subinhibitory effects (PA SMEs) on bacteria may provide additional, valuable information for the rational use of a drug in clinical practice. In this study tilmicosin was the most active antibiotic tested against P. multocida type D with MICs ranging from 4-16 mg/l. Roxithromycin and tilmicosin induced a statistically significantly longer PAE than did tylosin against P. multocida types A and D (P < 0.05). The duration of PAEs and PA SMEs were proportional to the concentrations of drugs used for exposure. The PA SMEs were substantially longer than PAEs on P. multocida. Tilmicosin had a longer PA SME compared with erythromycin, roxithromycin and tylosin for P. multocida. The computerized incubator used in the present study provided an efficient and convenient determination of PAE and PA SME, allowing frequent measurements of the bacterial growth.

Anti-Bacterial Agents↗
PubMed2001

Conditioning with high-dose cyclophosphamide may not be sufficient to provide a long-term remission of paroxysmal nocturnal hemoglobinuria following syngeneic peripheral blood stem cell transplantation.

A patient with paroxysmal nocturnal hemoglobinuria (PNH) received a syngeneic peripheral blood stem cell transplant (PBSCT) with high-dose cyclophosphamide (CY) conditioning. He had a reasonable engraftment and complete hematologic recovery. However, at 12 months after PBSCT, he became symptomatic and peripheral blood cells were almost entirely composed of glycosylphosphatidylinositol-anchored proteins deficient cells. This case suggests that high-dose CY may not exert a significant effect on PNH clones in the long term, although it had been effective in allogeneic BMT. In view of the possible autoimmune basis, it seems to be necessary to include other immunosuppressive therapy including ALG in addition to CY.

Adult↗
PubMed2001

Breast reconstruction after mastectomy: a survey of general surgeons in Singapore.

BACKGROUND: Breast cancer is the leading malignancy among women in Singapore. In the West as many as 30% of eligible patients undergo some form of reconstruction, but in Singapore breast reconstruction is not often performed. METHODS: A postal survey of general surgeons in Singapore (response rate of 46%) was conducted to ascertain the factors influencing their decision to refer for reconstruction and the possible concerns they had about reconstruction. RESULTS: Age, anticipated psychosocial morbidity and the need for adjuvant therapy were the most important factors identified. The survey also found that almost 30% of respondents were unsure of whether reconstruction would mask recurrence. Despite this, almost 80% of respondents felt that reconstruction was worth the effort, but 55% (compared to less than 20% in the West) felt that patients did not want reconstruction despite being advised of its availability. CONCLUSION: Lack of information and the perception that patients would not want reconstruction may be important reasons for the low emphasis placed on the role of breast reconstruction in post-mastectomy patients.

Age Factors↗
PubMed2001

Immunological alterations associated with Plasmodium vivax malaria in South Korea.

Various haematological and immunological studies on patients infected with Plasmodium vivax were undertaken, at diagnosis (day 0), after treatment with chloroquine but during primaquine treatment (day 10) and after all treatment (day 59), in South Korea (where there has been a recent and abrupt increase in the incidence of such infection). The main aims were to gain an understanding of the haemto-immunological alterations of this malarial infection, both before and after treatment, and to identify at least one useful marker for the diagnosis and post-treatment monitoring of P. vivax malaria. Thirty-eight patients with P. vivax malaria were compared with 20, apparently healthy controls. At diagnosis, the patients had lymphopenia, marked eosinopenia (the eosinophil count being correlated with the platelet count) and thrombopenia. Cells of most of the lymphocyte subsets investigated [i.e. CD3+, CD8+, CD19+, CD56+, CD3-/CD56+ and CD8+/CD56+ but not CD4+, CD3+/CD56+ or CD25+] were significantly less common among the lymphocytes of patients at diagnosis than among those of the controls. After initiating treatment, the numbers of CD19+ lymphocytes gradually increased (to normal values by day 59), whereas those of CD3+/56+ lymphocytes remained abnormally low throughout the follow-up period. The proportions of lymphocytes identified as CD4+ appeared to be unaffected by treatment. Although serum concentrations of IgE (and, to a lesser extent, IgM) were elevated in the patients at diagnosis, they were subnormal on day 10 post-treatment and normal at the day-59 follow-up. Serum concentrations of IgG and IgA in the patients were always found to be similar to those in the controls. At diagnosis the serum concentrations of complements C3 and C4 were significantly elevated in the patients. C3 remained at the same high concentration during follow-up but the concentration of C4, like that of IgE, was found to be subnormal on day 10 and normal 7 weeks later. The level of parasitaemia (%) was only found to be significantly correlated with haemoglobin concentration. The observation of eosinopenia with elevated IgE and C4 could be a useful indicator of P. vivax malaria, and treatment response could be followed by serial monitoring of serum concentrations of IgE and C4.

Adolescent↗