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Biomedical subjects

C Yap

Publications and source records attributed to C Yap.

At least 19 recordsLinked to original sources
PubMed2006

Acute supraclavicular skin toxicity in patients undergoing radiotherapy for breast cancer: an evaluation of the 'T'-grip method of patient positioning.

AIMS: Supraclavicular fossa (SCF) radiotherapy plays an important part in the adjuvant management of breast cancer but data on acute radiotherapy toxicity are lacking, particularly when differing patient treatment positions are used to allow computed tomography planning or to reduce cardiac doses. MATERIALS AND METHODS: We evaluated SCF and breast/chest wall acute skin toxicity in a cohort of 92 women with breast cancer, who were planned in a 'T'-grip (n = 72) or 90 degrees-grip (n = 20) position, while 'on treatment' and at 6 weeks. The modified Radiation Therapy Oncology Group (RTOG) criteria were used to score toxicity. Data on age, body mass index, smoking history, type of breast operation, prior chemotherapy, radiation dose, number of fields and field size were recorded and correlated with outcome. RESULTS: Maximum SCF reaction score was RTOG 2a, with no moist desquamation observed. SCF reactions were less severe compared with chest wall reactions and no worse than breast reactions. There was significant resolution of toxicity at 6 weeks. SCF radiotherapy in 'T'-grip patients was well tolerated and no worse than the 90 degees-grip group. Pain scores and sore throat occurrences were minimal. Univariate and multivariate analyses showed that smoking was associated with worsening SCF toxicity (odds ratio [OR] 2.92; P = 0.045) and delayed healing. Incremental SCF dose worsened toxicity (OR 3.65; P = 0.023). Smoking worsened breast but not chest wall toxicity. CONCLUSIONS: SCF radiotherapy was at least as well tolerated as breast radiotherapy and better tolerated than chest wall radiotherapy. The 'T'-grip position did not affect toxicity negatively. Smoking and radiation dose affected SCF toxicity.

Adult↗
PubMed2004

Pre and post operative medical therapy for endometriosis surgery.

BACKGROUND: Endometriosis is a common gynaecological condition which affects approximately 10% of women of reproductive age (Askenazi 1997). There is a range of symptoms and most commonly women present with dysmenorrhoea, pelvic pain, infertility or a pelvic mass. Direct visualisation and biopsy during laparoscopy or laparotomy is the gold standard diagnostic test for this condition and enables the gynaecologist to identify the location, extent and severity of the disease. Surgical therapy can be performed concurrently with diagnostic surgery and may include removal (excision) or destruction (ablation) of endometriotic tissue, division of adhesions and removal of endometriotic cysts. Laparoscopic excision or ablation of endometriosis has been shown to be effective in the management of pain in mild-moderate endometriosis. Adjunctive medical treatment pre or post-operatively may prolong the symptom-free interval. OBJECTIVES: To determine the effectiveness of systemic medical therapies used for hormonal suppression before or after surgery for endometriosis, or before and after surgery for endometriosis in the eradication of endometriosis, improvement of symptoms, pregnancy rates and overall tolerability by comparing them with no treatment or placebo. SEARCH STRATEGY: We searched the Cochrane Menstrual Disorders and Subfertility group trials register (searched 10 September 2003), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3 2003), MEDLINE (January 1966 to September 2003), EMBASE (January 1985 to September 2003) and reference lists of articles. We also contacted researchers in the field. SELECTION CRITERIA: Trials were included if they were randomised controlled trials of the use of systemic medical therapies for hormonal suppression before or after, or before and after surgery for endometriosis. DATA COLLECTION AND ANALYSIS: Data extraction and quality assessment was performed independently by using relative risk or weighted mean difference and 95% confidence intervals. MAIN RESULTS: Eleven trials were included in the review. One study comparing pre-surgical medical therapy with surgery alone showed a significant improvement in AFS scores in the medical therapy group (WMD -9.60, 95% CI -11.42 to -7.78) but this may or may not be associated with better outcomes for the patients. Post surgical hormonal suppression of endometriosis compared to surgery alone (either no medical therapy or placebo) showed no benefit for the outcomes of pain or pregnancy rates but a significant improvement in disease recurrence (AFS scores (WMD -2.30, 95% CI -4.02 to -0.58)). There were no trials identified in the search that compared hormonal suppression of endometriosis before and after surgery with surgery alone. There is no significant difference between pre surgery hormonal suppression and post surgery hormonal suppression for the outcome of pain in the one trial identified (RR 1.01, 95% CI 0.49 to 2.07). Information concerning AFS scores and ease of surgery was reported only as a descriptive summary so any difference between the groups can not be quantified from the information in the report of this trial. REVIEWERS' CONCLUSIONS: There is insufficient evidence from the studies identified to conclude that hormonal suppression in association with surgery for endometriosis is associated with a significant benefit with regard to any of the outcomes identified. There may be a benefit of improvement in AFS scores with the pre-surgical use of medical therapy. The possible benefit should be weighed in the context of the adverse effects and costs of these therapies.

Chemotherapy, Adjuvant↗
PubMed2004

Dynamic EBV gene loads in renal, hepatic, and cardiothoracic transplant recipients as determined by real-time PCR light cycler.

BACKGROUND: Epstein-Barr virus (EBV) is recognised as one of the causative agents for most cases of post-transplant lymphoproliferative disease (PTLD). Elevated levels of EBV DNA are known to be associated with the onset of PTLD, but little information is available regarding how EBV loads change with time in asymptomatic transplant recipients following transplantation. Our aims were to study the trend of EBV loads in renal (RTx), hepatic, and cardiothoracic transplant recipients and to compare their EBV loads with other healthy and patient controls. METHODS: A prospective study was performed using a real-time TaqMan polymerase chain reaction technique to measure EBV DNA loads from three types of organ transplant recipients and haemodialysis patients (HD). Their results were then compared with those from the healthy controls (HC); monospot test negative (MN-) and infectious mononucleosis positive (IM+) patients; patients who were previously treated for PTLD (pPTLD); those who were currently diagnosed to have PTLD (PTLD+); and patients who had a stable renal, hepatic, or cardiothoracic graft for more than a year. RESULTS: Post-transplant EBV loads were significantly higher than the pre-transplant levels. Asymptomatic transplant recipients were differentiated from the PTLD+group at 600 genome copies of EBV/mug DNA, and from IM+group at 100 genome copies. Both HC and MN- groups had significantly lower EBV loads than the three transplant groups. The dynamic change of EBV loads in RTx was greater in the first post-transplant month when compared with the HD group. All transplant recipients had transient rises of EBV loads whereas EBV load continued to rise in one suspected PTLD patient. CONCLUSIONS: Asymptomatic transplant recipients had higher baseline post-transplant EBV levels than the non-transplant and MN- groups. The rising post-transplant EBV load in these transplant recipients did not seem to be sustained for longer than 2 weeks. However, in a PTLD+patient the rising EBV load continued over a period of 4 weeks. Hence, the dynamic pattern of EBV loads is more important than absolute EBV DNA measurements alone in identifying those who might go on to develop PTLD.

Adolescent↗
PubMed2004

In vitro biological characteristics of human cord blood-derived megakaryocytes.

INTRODUCTION: Umbilical cord blood (CB) has been used as an alternative source for haematopoietic stem cell transplantation (HSCT) in recent years. However, delayed platelet recovery is frequently associated with CB HSCT. Megakaryocytes (Mk) are the specialised precursors of platelets and they are among the rarest haemopoietic cell types. Despite the rapid expansion of our knowledge of megakaryopoiesis in recent years, many questions, such as the molecular regulatory mechanisms in Mk differentiation and maturation, platelet formation and release, remain unanswered in CB-derived megakaryopoiesis. Variations can be seen from the literature by individual investigators using different approaches for Mk-specific differentiation and maturation induction. The development of in vitro culture methods to obtain sufficient numbers of Mks from readily available haematopoietic stem cells is of value for both basic research and clinical applications. MATERIALS AND METHODS: The CD34+ cells from cord blood samples were cultured in serum-free medium with haematopoietic growth factors (GFs), such as IL-3, stem cell factor (SCF), and thrombopoietin (Tpo). The differentiation of Mk was monitored using Mk- and platelet-specific monoclonal antibodies and flow cytometric analysis. The morphology of the cultured cells was studied by both light and electronic microscopy (LM and EM). The involvement of the human Notch gene family members was studied by real time-polymerase chain reaction (RT-PCR). Maturation of the cultured Mks was studied using flow cytometric analysis for both platelet-specific surface markers and enodomitosis. Platelet activation was assessed in the cytoplasmic fragments harvested from the cultures. RESULTS: Specific Mk differentiation of >70% resulted from a 2-step culture approach using IL-3, SCF and Tpo for 7 days followed by Tpo only for another 14 days. RT-PCR showed high-level expression of both Notch-1 and its ligand, Jagged-1, in the cultured Mks. Limited levels of polyploidy (>4N, endomitosis, EnM) were observed in the cultured Mks. The results also showed that the cytoplasmic fragments from the cultures responded to platelet activation reagents, including ADP and collagen, marked by upregulation of platelet-specific activation markers, such as CD62P (P-selectin) and PAC-1 (gpalphaIIbbeta3). CONCLUSION: The methods used in this study are specific for differentiation of Mk from CB CD34+ cell, which can partially mature and produce functional platelets in vitro. This approach for human Mk differentiation could be further optimised and may be adapted on larger scales for clinical purposes.

Antibodies, Monoclonal↗
PubMed2003

Investigating the infertile couple.

INTRODUCTION: Investigations play a pivotal role in the workup for infertility. The results must be interpreted carefully as these assess dynamic function. Evidence-based guidelines are useful in the selection of appropriate tests. MATERIALS AND METHODS: A review of current evidence-based guidelines for the investigation and management of the infertile couple is undertaken. RESULTS: The main areas that correlate with fecundability are ovulatory function, tubal patency and semen analysis. CONCLUSION: The appropriate selection of investigations based on problem areas identified by history and physical examination would guide the physician in the management of the infertile couple.

Adult↗
PubMed2003

Pregnancy following embolisation of uterine arteriovenous malformation--a case report.

INTRODUCTION: Pregnancy following successful embolisation of a uterine arteriovenous malformation (AVM) is rare. Hypovascularity of treated areas affecting placentation and fetal growth has been postulated to be the cause for adverse pregnancy outcomes. CLINICAL PICTURE: A 37-year-old multiparous lady presented with anaemia from repeated heavy vaginal bleeding from an iatrogenic uterine AVM. This was diagnosed with power Doppler ultrasonography and embolised after pelvis angiography with hystoacryl and lipiodol. Following this she had a spontaneous pregnancy with a normal outcome. CONCLUSION: There are no distinguishing clinical features of a uterine AVM. An index of suspicion and power Doppler sonography help in reaching a diagnosis. Dilatation and curettage should be avoided as this can precipitate torrential vaginal bleeding.

Adult↗
PubMed2002

Use of real-time PCR to measure Epstein-Barr virus genomes in whole blood.

The measurement of the Epstein-Barr viral load in peripheral blood has been recognised as an important way of monitoring the response to treatment in patients with Epstein-Barr virus (EBV)-related malignancies. In particular, EBV load in transplant recipients can be used as a predictive parameter for Post-transplant Lymphoproliferative Disorder (PTLD). The aim was to develop a rapid and reliable PCR protocol for the quantification of the cell-associated EBV genome. Real-time PCR using TaqMan methodology was established. This technique was applied to determine the EBV load in various study groups including healthy controls, transplant recipients, patients on haemodialysis, and patients with infectious mononucleosis. The baseline level of EBV genomes in the immunosuppressed renal transplant recipients was significantly different from that in the healthy controls.

DNA, Viral↗
PubMed2002

Temperature-entropy formulation of thermoelectric thermodynamic cycles.

A temperature-entropy formulation is derived for thermoelectric devices. Thermoelectric chiller and generator cycles can then be cast in the same irreversible thermodynamics framework commonly applied to conventional large-scale cooling and power generation equipment, including a transparent identification of the principal energy flows and performance bottlenecks (dissipation). Distinct differences in chiller versus generator mode are highlighted and illustrated with data from commercial thermoelectric units.

Journal Article↗
PubMed2001

Clinical management of PCOS.

The polycystic ovary syndrome (PCOS) is a heterogeneous condition with genetic predisposition. It is characterized by a myriad of symptoms including oligomenorrhea or amenorrhea, anovulation or infertility, hirsutism or acne. Insulin resistance appears to be an important factor in PCOS though the lack of an etiology has led to symptom oriented therapy which includes lifestyle modification, the use of cyclical progestagens and antiandrogens. Ovulation induction by drug therapy and ovarian drilling aims to treat subfertility in women with PCOS. Therapeutic approaches to PCOS remain an ongoing source of debate. Insulin sensitizing agents may bring new hope in therapy. Future research is aimed at shedding light on the pathophysiology so as to optimize treatment of women with PCOS.

Contraceptives, Oral↗
PubMed2001

Corneal temperature reversal after storage in Chen medium compared with Optisol GS.

PURPOSE: To compare corneal endothelial cell function by measuring corneal thickness during temperature reversal between corneas stored in two different storage media, Optisol GS and Chen Medium (CM). METHODS: Twenty paired corneas from 10 human donors were randomly assigned for storage at 4 degrees C in Optisol GS (10 corneas) or CM (10 corneas). The storage media were masked, and measurements were done in a masked fashion. After storage for 48 hours, corneal thickness was measured by ultrasonic pachymetry at 2-hour intervals for 12 hours, during which time the corneas were perfused with BSS (balanced salt solution) Plus at 37 degrees C. Scanning electron microscopy of two pairs of corneas from two donors was performed to assess ultrastructural change after 12 hours of warming. RESULTS: Corneal thickness decreased during the first 4 hours of the warming period and then increased during the 6-to 12-hour warming period. These changes in corneal thickness over time were similar for the two storage media (p = 0.212). Scanning electron microscopy showed greater amounts of endothelial cell disruption in Optisol GS-stored corneas than those stored in CM after 12 hours of warming and perfusion. CONCLUSIONS: The endothelial pump of corneas stored in CM appear to be as well-preserved as those stored in Optisol GS, although greater endothelial disruption may be present with Optisol GS by scanning electron microscopy. Further studies are required to compare the clinical effectiveness of these two media.

Aged↗
PubMed2001

Effect of whole-body (18)F-FDG PET imaging on clinical staging and management of patients with malignant lymphoma.

UNLABELLED: Correct staging is important in selecting the appropriate treatment for lymphoma patients. PET imaging with (18)F-FDG is useful for staging of lymphoma as well as for monitoring of therapy. However, to our knowledge, the clinical impact of PET on staging and management of lymphoma patients has not been reported. METHODS: Standardized questionnaires were mailed to referring physicians asking them whether and how the results of PET imaging had influenced clinical staging and management of the disease in their patients. Management changes, when present, were classified as intermodality (e.g., medical to surgical, surgical to radiation, medical to no treatment) or intramodality (e.g., altered medical, surgical, or radiotherapy approach). RESULTS: The referring physicians returned 52 of 108 questionnaires (48.1%). Physicians indicated that PET led to a change in the clinical stage in 44% of patients: 21% were upstaged and 23% were downstaged. Findings of the PET examination resulted in intermodality changes in management in 42% of patients, in intramodality changes in 10%, and in a combination of the management changes in 10%. Other, not further specified, treatment changes were reported in 6% of patients. PET did not result in any management changes in only 32% of patients. CONCLUSION: This survey-based study of referring physicians indicates that FDG PET has a major impact on the management of lymphoma patients, contributing to changes in clinical stage in 44% and changes in treatment in >60% of cases.

Adolescent↗
PubMed2000

Ontogeny: the evolution of an oocyte.

The physiology of oocyte development, maturation, and selection forms the basis for understanding ovarian follicle dynamics, reproductive function and ovulation induction. The number of ovarian follicles with which women are invested from birth and the rate of decline determine their reproductive lifespan. The processes of atresia and apoptosis constantly deplete this finite store. The initiation of follicle growth involves complex chemical signaling and ensures that a cohort of follicles is prepared for recruitment monthly. The effects of gonadotrophins, autocrine signals, and the degree of vascularization further determine dominance and the selection of an oocyte for ovulation.

Female↗
PubMed2000

Prevention of mechanical stretch-induced endothelial and smooth muscle cell injury in experimental vein grafts.

Vein grafts are subject to increased tensile stress due to exposure to arterial blood pressure, which has been hypothesized to induce endothelial cell (EC) and smooth muscle cell (SMC) injury. This study was designed to verify this hypothesis and to develop a tissue engineering approach that can be used to prevent these pathological events. Two experimental models were created in rats to achieve these goals: (1) a nonengineered vein graft with increased tensile stress, which was created by grafting a jugular vein into the abdominal aorta using a conventional end-to-end anastomotic technique; and (2) an engineered vein graft with reduced tensile stress, which was created by restricting a vein graft into a cylindrical sheath constructed using a polytetrafluoroethylene membrane. The integrity of ECs in these models was examined by using a silver nitrate staining method, and the integrity of SMCs was assessed by using a fluorescein phalloidin-labeling technique. It was found that nonengineered vein grafts were associated with early EC denudation with a change in EC coverage from 100 percent in normal jugular veins to 36 +/- 10, 28 +/- 12, 18 +/- 9, 44 +/- 15, 80 +/- 13, and 97 +/- 6 percent at 1 and 6 hours and 1, 5, 10, and 30 days, respectively. Similarly, rapid SMC actin filament degradation was found during the early period with a change in SMC coverage from approximately 94 percent in normal jugular veins to 80 +/- 10, 41 +/- 17, 25 +/- 9, 51 +/- 15, 79 +/- 15, 98 +/- 2 percent at 1 and 6 hours and 1, 5, 10, and 30 days, respectively, in nonengineered vein grafts. In engineered vein grafts with reduced tensile stress, EC denudation and SMC actin filament degradation were prevented significantly. These results suggested that mechanical stretch due to increased tensile stress contributed to EC and SMC injury in experimental vein grafts, and these pathological events could be partially prevented when tensile stress was reduced by using a biomechanical engineering approach.

Anastomosis, Surgical↗
PubMed2000

Variability in CD34+ cell counts in umbilical cord blood: implications for cord blood transplants.

OBJECTIVE: To determine if total nucleated cell counts alone are sufficient for predicting the efficacy of cord blood units for transplant from neonatal umbilical cord blood samples. METHODS: Umbilical cord blood samples were collected from 200 mothers at delivery and the cord blood units processed. The total nucleated cells and CD34+ cells were enumerated and compared for each sample. RESULTS: Despite an apparent linear correlation between total nucleated cell counts and CD34+ cell counts, each group of total nucleated cell counts demonstrated a high degree of variation in CD34+ cell counts and could be as low as 0.1% of total nucleated cell counts. CONCLUSIONS: Large variations in CD34+ cell counts per total nucleated cell count are present for cord blood units from neonatal umbilical cord samples. Hence a CD34+ cell count for each cord blood unit would improve selection of samples for transplant.

Antigens, CD34↗
PubMed1999

Role of CYP2E1 in the pathogenesis of alcoholic liver disease: modifications by cAMP and ubiquitin-proteasome pathway.

The ethanol inducible isoform of cytochrome P450, CYP2E1, may play a role in ethanol-induced liver injury. Therefore, the factors which govern CYP2E1 degradation and turnover were investigated. These factors include cAMP, ubiquitin, proteasomal enzymes and CYP2E1 mRNA. Rats fed ethanol or pair-fed isocaloric dextrose were pair-fed with rats fed ethanol or dextrose treated with cAMP for 2 months. The liver pathology, regenerative activity, fatty acid composition, NFkappaB activation, ubiquitin conjugates and proteasomal enzymes were measured as were the apoprotein levels of CYP2E1, CYP3A, CYP4A and mRNA levels for CYP2E1 and ubiquitin expression. The results showed, that the cAMP treatment ameliorated the increase liver fat storage and changes in the fatty acid composition in the livers of ethanol fed rats. Other histologic features of alcoholic liver disease were not changed. Western blot quantitation showed that the amount of ubiquitin and ubiquitin conjugates were markedly reduced by ethanol treatment. Similarly, ethanol decreased the level of ubiquitin mRNA. cAMP ameliorated the inhibition of the proteasomal enzyme proteolysis caused by ethanol feeding. The ethanol-induced increase in the CYP2E1 protein was partially inhibited by cAMP treatment. cAMP treatment decreased CYP2E1 mRNA levels in both ethanol-fed and pair fed control rats. Likewise NFkappaB activation was not increased by ethanol but cAMP reduced the level of NFkappaB activation. CAMP treatment also reduced CYP4A but not CYP3A. The results support the concept that cAMP treatment partially protects the liver from ethanol-induced fatty liver by reducing CYP2E1 induction through cAMP's effects on CYP2E1 synthesis.

Animals↗
PubMed1999

Consumption of foods from the WIC food packages of Chinese prenatal patients on the US west coast.

OBJECTIVE: To assess consumption of foods from food packages provided by the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) among 80 Chinese prenatal WIC recipients living in Oakland or San Francisco, Calif. DESIGN: During a single interview, a food frequency questionnaire was used to assess WIC food consumption by the prenatal patients for the period before and after receipt of WIC vouchers. SETTING: The study was conducted at Asian Health Services, Oakland, and the Chinatown Public Health Center of the San Francisco Department of Public Health in California. SUBJECTS: Eighty low-income Chinese prenatal women with limited education and limited ability to speak English, aged 21 to 43 years, with gestational stages of 15 to 38 weeks. STATISTICAL ANALYSES PERFORMED: Descriptive statistics (frequency and percent distribution) were used to report the findings of the study. RESULTS: Subjects reported that before receiving WIC vouchers, milk, eggs, and juice were the only foods in their WIC food package that had been consumed frequently (> 5 times/week) in their daily diet. Other WIC foods, including cheese, peanut butter, dried beans, and hot and cold cereals, were consumed infrequently (0 to 1 time/month). Subjects reported that with the availability of WIC vouchers, milk, eggs, and juice remained frequently consumed with 81% to 100% of monthly supply as the most prevalent reported consumption rate. Dried beans and hot and cold cereals were also consumed frequently. Cheese remained poorly consumed (0% to 20% of the monthly supply). As many as 74 of 80 subjects stated that they had shared foods from their own WIC package, except milk, with their families. The use of any WIC foods provided to other children in the family was not assessed in this study. APPLICATIONS: Data from this study indicate that most WIC foods were well used by Chinese prenatal patients. The most notable exception was cheese, which was poorly consumed. The ready consumption of milk by pregnant Chinese WIC recipients in this study suggests that milk may be readily consumed by these women, even though it is atypical of the Asian diet. The WIC food package for Chinese prenatal patients may be improved by omitting cheese and substituting more milk and/or foods such as tofu and dark green leafy vegetables.

Adult↗
PubMed1998

Antiphospholipids and pregnancy--a review.

The presence of antiphospholipid antibodies is associated with a clinical syndrome characterised by thrombocytopenia, recurrent arterial and venous thromboses and recurrent fetal loss. The etiology is unknown but leads to an abnormal autoimmune response. Platelet aggregation and thrombosis follow. The mainstay of treatment is low dose aspirin, heparin and corticosteroids.

Abortion, Habitual↗