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Biomedical subjects

P M Yuen

Publications and source records attributed to P M Yuen.

At least 55 records · Page 3Linked to original sources
PubMed1999

Outcomes and prognostic factors of Chinese children with acute lymphoblastic leukemia in Hong Kong: preliminary results.

BACKGROUND: The Chinese population is the biggest ethnic group in the world. However, there are few reports on the treatment outcome of childhood acute lymphoblastic leukaemia (ALL) among the Chinese population. PROCEDURE: Sixty-five children with ALL were treated with a modified protocol of the Medical Research Council United Kingdom Acute Lymphoblastic Leukaemia protocol X(MRC UKALL X) at the Prince of Wales Hospital, Hong Kong. Most patients were ethnic Chinese. They were divided into groups A and B, depending on whether their presenting leucocyte count being was less or greater than 50 x 10(9)/l, respectively. Group A patients of received induction, early intensification (week 5), cranial irradiation, and maintenance for 3 years. Group B patients received an additional late intensification (week 20). RESULTS: The median follow-up duration was 6.8 years(range: 3.4-10.1 years). The event-free and overall survival rates of all patients at 7 years were 66% (confidence interval [CI] 53-76) and 75% (CI 63-84), respectively. The event-free survival rates of groups A and B at 7 years were 67% (CI 52-79) and 60% (CI 32-80), respectively (P= 0.39). The overall survival rates of groups A and B at 7 years were 80% (CI 66-89) and 60% (CI 32-80), respectively (P = 0.07). With this treatment protocol, the factors which adversely affected the outcome were age (<2 years and >10 years) and T-cell subtype. Sex, white blood count at diagnosis, and FAB subtypes were not statistically significant prognostic factors. CONCLUSIONS: The treatment outcomes were comparable with those reported from the MRC UKALL X trials.

Adolescent↗
PubMed1999

Ocular complications of pediatric bone marrow transplantation.

OBJECTIVE: To investigate the ocular complications in pediatric bone marrow transplantation (BMT) patients. DESIGN: Cross-sectional study. PARTICIPANTS: A total of 29 pediatric BMT patients were studied. TESTING: Comprehensive ophthalmic check-up, including best-corrected visual acuity, intraocular pressure (IOP), Schirmer's test, tear breakup time, and slit-lamp and fundus examinations, was performed. MAIN OUTCOME MEASURES: Tear film instability and its related complications, IOP, cataract, and fundus lesions were measured. RESULTS: The mean age of patients was 9.1 years (range, 1.5-15 years). The mean post-BMT duration was 20.2 months (range, 3-54 months). Fifteen patients (51.7%) had tear abnormalities. Subconjunctival fibrosis was detected in two patients (6.9%). Dry and scaly skin of the eyelids was seen in one patient (3.4%). Lens opacities were found in 2 (33.3%) of 6 irradiated patients and 2 (8.7%) of 23 nonirradiated patients. Two patients (6.9%) had fundus changes, one with unilateral epiretinal membrane and the other with bilateral multiple discrete chorioretinal hypopigmented lesions in the middle to peripheral part of the retina. The overall complication rates for the anterior and posterior segments were 75.8% and 6.9%, respectively. CONCLUSION: Ocular manifestations of BMT in children are not uncommon. The most common anterior segment problem is tear dysfunction. Posterior segment complications are less common but do exist. High rate of cataract formation is reported, and this probably is the most important long-term "amblyogenic" problem in these immature eyes. Awareness and management of these problems with routine eye examination and early intervention are recommended.

Adolescent↗
PubMed1999

Granulocyte colony-stimulating factor-mobilized peripheral blood stem cells in beta-thalassemia patients: kinetics of mobilization and composition of apheresis product.

beta-Thalassemias are often associated with bone marrow expansion and immunomodulation in terms of lymphocyte subsets and cytokine levels in the peripheral blood. The mobilization of peripheral blood stem cells (PBSC) by cytokines in such a background has not been reported. If achieved, the apheresis product could be used as a stem cell back-up for beta-thalassemia patients prior to bone marrow transplant. PBSC collection may also become a means for providing stem and progenitor cells for gene manipulation and therapy of this disorder. The aim of the study was to assess the administration of G-CSF in mobilizing stem and progenitor cells in these patients and to compare the kinetics of CD34+ cells and lymphocyte subsets with those of healthy PBSC donors. Results showed that the CD34+ cells were effectively mobilized by G-CSF (10-16 micrograms/day per kg) in 20 thalassemia patients and 11 healthy donors. Although no significant difference was observed in levels of daily stem cell counts between the two groups of subjects, a 1 day delay in achieving peak levels of CD34+ cells was observed in the majority of thalassemia patients. The peak increase of CD34+ cells was 21.5 +/- 6.1-fold and 30.8 +/- 7.6-fold of the basal steady-state levels in thalassemia patients and healthy donors, respectively. Similar to the situation of healthy donors, G-CSF stimulated essentially the CD34+ cells and the myeloid lineage (granulocytes, monocytes) in thalassemia patients and had a slight effect on lymphocyte subsets (T-helper, T-suppressor, NK, and B cells) and activation (CD25, HLA-DR, and CD45RO). Compositions of the apheresis products, including CD34+CD38-, CD34+CD33+ and CD34+HLA-DR- cells, were similar in the two groups of subjects. Correlation studies showed that the level of CD34+ cells in the PB is a good indicator of that in the apheresis product (r = 0.88, p < 0.001). The study has demonstrated that under close monitoring of CD34+ cell levels in PB, the mobilization by G-CSF and collection of PBSC in beta-thalassemia patients are feasible.

Adolescent↗
PubMed1999

Primary orbital Ewing's sarcoma: report of a case and review of the literature.

Primary orbital Ewing's sarcoma is a very rare condition. Since the first case was reported in 1950, only 7 other cases have been reported in the English literature. Herein we describe the ninth, the only bilateral and the youngest case of primary orbital Ewing's sarcoma occurring in a 2-year-old boy, who presented to us with bilateral painless proptosis. Tissue biopsy of the tumour was obtained through the nasal sinus. Immunohistological studies of the biopsy tissue confirmed the diagnosis of Ewing's sarcoma. No distant site of the tumour was found so this was considered a primary orbital tumour. Combined chemotherapy and radiotherapy without surgical resection achieved an encouraging result in that the patient has remained in remission for 30 months after completion of treatment. The successful use of combined chemotherapy and radiotherapy, without surgery, adds further support to evidence that surgical excision may be avoided in selected cases of primary orbital Ewing's sarcoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Busulphan level and early mortality in thalassaemia patients after BMT.

The aim of the study was to correlate busulphan (BU) levels of thalassaemia patients with outcome of allogeneic transplant. BU levels were measured by gas chromatography mass fragmentography. All patients received a standardised dose of BU 16 mg/kg, and cyclophosphamide 150 or 200 mg/kg. For area-under-the-curve analysis (AUC), blood samples were obtained at 0, 1, 2, 3, 4 and 6 h after the first and fifth dose for all patients, and additional levels were measured after ninth and/or 13th dose in most patients. Outcome parameters examined included veno-occlusive disease of liver (VOD), idiopathic interstitial pneumonitis, chimerism, and day 90 survival. Twenty consecutive thalassaemia patients who underwent haematopoietic stem cell transplantation were studied. The median age at transplant was 11.2 years (range 3-21 years). Mean BU AUC levels were correlated with age at transplant (r = 0.58, P = 0.007). Nine patients developed VOD and six had mixed chimerism, but these did not correlate with mean BU AUC level. Four patients died before day 50 from VOD and interstitial pneumonitis. Patients with BU AUC levels greater than the median (908 micromol x min/l) had significantly lower probability of survival at day 90 (60%), whereas patients with BU AUC level less than the median all survived beyond day 90. No patient had graft rejection. In conclusion, a high BU AUC level was associated with a higher treatment-related mortality in thalassaemia patients after transplant.

Adolescent↗
PubMed1999

Ex vivo expansion of enriched CD34+ cells from neonatal blood in the presence of thrombopoietin, a comparison with cord blood and bone marrow.

Neonatal blood (NB) contains substantial numbers of stem and progenitor cells which decline rapidly after birth. Using a combination of cord blood (CB) and NB, we performed a successful, sibling transplant for a thalassaemia patient, leading to the proposal that NB could be used as an adjunct to CB for transplantation. This study was aimed at addressing the feasibility of expanding NB and thus minimizing the volume needed from a NB collection. In the presence of early acting cytokines interleukin-1beta (IL-1beta), IL-3, IL-6, stem cell factor (SCF), flt-3 ligand with and without thrombopoietin (Tpo), we compared the expansion capacity of CD34+ enriched cells from CB, NB and bone marrow (BM). Flow cytometry and colony-forming unit (CFU) analyses show that Tpo significantly increased the expansion of CD34+ cells from CB and NB to early and committed progenitors. No significant difference was observed between the expansion of CB and NB at 7, 14 or 21 days of culture in terms of CFU, CD34+ and CD61+ cell subsets. The expansion capacity of BM was significantly lower than that of NB or CB, possibly related to the low proportion of CD34+ CD38- cells observed at day 0. There was a relatively rapid expansion of NB which was evident at day 7 whilst the expansion of CB and BM remained low, suggesting a speedy maturation process in the postnatal infant. The expanded cells, being heterogeneous in their morphology and cell surface marker expression, were mostly of the myeloid lineage (CD45+, CD33+ and HLA-DR+). Our results showed that the expansion capacity of NB is comparable to that of CB and if transplanted, the expanded products of NB might contribute to the engraftment kinetics of the neutrophil and megakaryocyte lineage.

Antigens, CD34↗
PubMed1999

Human neonatal blood: stem cell content, kinetics of CD34+ cell decline and ex vivo expansion capacity.

Haemopoietic stem cells are present in fetal blood but their levels decline rapidly in the peripheral circulation of the infant after birth. We previously reported a case of stem cell transplant in a beta-thalassaemia boy using a combination of the cord blood (CB) and neonatal blood (NB) of his sister. This transplant resulted in a successful engraftment. To investigate the possibility of using NB to supplement CB for related transplants, we further characterized stem and progenitor cells and lymphocyte subsets in 20 NB samples, comparing the findings with those in 20 CB samples. Our data showed that NB contained substantial levels of CD34+ cells, CD34+CD38- cells, colony-forming units-granulocyte macrophage (CFU-GM), colony forming units-erythroid (CFU-E), burst forming units-erythroid (BFU-E) and long-term culture initiating cells (LTCIC). NB was similar to CB in the levels of T lymphocytes, but the amounts of B lymphocytes and natural killer cells were higher in CB (P = 0.033, P= 0.001, respectively). The kinetics of CD34+ cells in NB was investigated in serial blood samples obtained from 10 full-term infants at 2, 4, 6, 8, 24 and 48h after birth. CD34+ cells decreased rapidly after birth, declining to only 30% of the 2h level at 48h (P<0012). The rate of decline was greatest in the first 4 h of life. NB from four infants was expanded by culturing the blood samples in the presence of thrombopoietin (Tpo), interleukin 1beta (IL1beta), IL-3, IL-6, flt-3 ligand and stem cell factor (SCF) for 7 d. This resulted in the increase of CD34+ cells, CFU-GM and CFU-MK by 271+/-179, 556+/-385 and 113+/-75 fold respectively. Three of the five samples expanded for 7 d contained LTCIC. These findings suggest that NB might be a supplementary or alternative source of stem cells to CB for transplant. The ethics and practicality of this approach deserve further exploration.

Antigens, CD34↗
PubMed1999

Mutations of OCTN2, an organic cation/carnitine transporter, lead to deficient cellular carnitine uptake in primary carnitine deficiency.

Systemic primary carnitine deficiency (CDSP, OMIM 212140) is an autosomal recessive disease characterized by low serum and intracellular concentrations of carnitine. CDSP may present with acute metabolic derangement simulating Reye's syndrome within the first 2 years of life. After 3 years of age, patients with CDSP may present with cardiomyopathy and muscle weakness. A linkage with D5S436 in 5q was reported in a family. A recently cloned homologue of the organic cation transporter, OCTN2, which has sodium-dependent carnitine uptake properties, was also mapped to the same locus. We screened for mutation in OCTN2 in a confirmed CDSP family. One truncating mutation (Trp132Stop) and one missense mutation (Pro478Leu) of OCTN2 were identified together with two silent polymorphisms. Expression of the mutant cDNAs revealed virtually no uptake activity for both mutations. Our data indicate that mutations in OCTN2 are responsible for CDSP. Identification of the underlying gene in this disease will allow rapid detection of carriers and postnatal diagnosis of affected patients.

Amino Acid Sequence↗
PubMed1999

Paracervical anaesthesia in outpatient hysteroscopy: a randomised double-blind placebo-controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of paracervical anaesthesia in reducing pain during outpatient hysteroscopy and endometrial biopsy. DESIGN: Prospective, randomised, placebo-controlled, double-blind study. POPULATION: One hundred women undergoing outpatient hysteroscopy and endometrial biopsy for abnormal uterine bleeding. INTERVENTIONS: Paracervical block using 10 mL of either 2% lignocaine or normal saline before the procedure. MAIN OUTCOME MEASURES: Evaluation of pain at different stages of hysteroscopy using a visual analogue scale together with blood pressure and heart rate monitoring. RESULTS: Compared with placebo, paracervical anaesthesia significantly reduced the pain only at the time of insertion of the hysteroscope, but not at the subsequent stages of the procedure. However, paracervical injection of lignocaine resulted in a higher incidence of bradycardia and hypotension. CONCLUSIONS: Paracervical anaesthesia not only fails to reduce pain during outpatient hysteroscopy and endometrial biopsy, but also carries a risk of inducing bradycardia and hypotension, which is probably a result of inadvertent intravascular injection.

Adult↗
PubMed1999

Patient's acceptance of outpatient hysteroscopy.

There is a trend towards performing hysteroscopy and endometrial biopsy on an outpatient basis, as this alleviates the need for both an inpatient stay and a general anesthesia. Despite the wide acceptance by medical staff, there are few publications on how patients actually tolerate and accept these procedures. We performed a survey on 185 patients attending the outpatient hysteroscopy clinic at a teaching hospital to assess the degree of pain and their acceptance to those procedures using a visual analogue scale. All procedures were successfully performed under no anesthesia without complications. The mean age of the patients was 48 (range 24-78) and 9.4% were nulliparas. The mean pain experienced was 4.7 (SD 2.7) during hysteroscopy and 5.0 (SD 2.9) during endometrial biopsy. The overall preference scores for the procedure to be done under was 3.1 (SD 3.7). About 7% of patients expressed a preference for an overnight stay in hospital after the procedure, but the preference score was low (2.5, SD 3.6). The procedure was well accepted (8.3, SD 2.4) and highly recommended by the patients (8.4, SD 2.9). Outpatient hysteroscopy is well accepted and tolerated by patients.

Adult↗
PubMed1998

Allogeneic peripheral blood stem cell transplant in children.

Allogeneic peripheral blood stem cell (PBSC) transplant has recently been introduced for the treatment of hematological malignancies. As the data were limited mainly to adult patients, this study aimed to assess the feasibility and safety of this procedure in pediatric patients and donors. Eleven children aged 2-16 years received allogeneic PBSC transplant for acute lymphoblastic leukemia (n = 4), acute myeloid leukemia (n = 1), myelodysplastic syndrome (n = 1), severe aplastic anemia (n = 3), and thalassemia (n = 2). Nine donors were human leukocyte antigen (HLA)-identical siblings and the other two were one antigen mismatched family members. Eight donors were younger than 18 years old (10 months to 17 years). Donors were primed with granulocyte colony-stimulating factor (G-CSF) at 10-16 micrograms/kg for 4-5 days. Aphereses were performed on 1 or 2 consecutive days, and the patients received a mean of 14.4 x 10(8)/kg nucleated cells, 6.9 x 10(6)/kg CD34 cells, and 6.9 x 10(8)/kg T cells. All patients achieved neutrophil counts of > 0.5 x 10(9)/l at a median of 16 days. Nine patients achieved platelet counts of > 20 x 10(9)/l at a median of 13 days. Grade II acute graft vs. host disease (GVHD) occurred in only one patient. Chronic GVHD was not observed in the seven patients with follow-up of more than 3 months. Eight patients remained in continuous complete remission after transplant ranged from 2 to 26 months. Allogeneic PBSC transplant appears safe in pediatric patients and donors, and it seems not to be associated with increase of acute GVHD or chronic GVHD.

Adolescent↗
PubMed1998

Metabolic and inflammatory responses after laparoscopic and abdominal hysterectomy.

OBJECTIVE: Our purpose was to quantify and compare the metabolic and inflammatory changes after laparoscopic and abdominal hysterectomy. STUDY DESIGN: Forty-four patients with no major medical disease requiring abdominal hysterectomy for benign disorders were randomly assigned to have laparoscopic hysterectomy (n = 20) and abdominal hysterectomy (n = 24). Venous blood and 24-hour urine samples were collected the day before and for each of the first 3 postoperative days. RESULTS: No differences were present in demographic characteristics, operating time, and uterine weight between the two groups. No major complications were encountered. The laparoscopic hysterectomy group had a significantly lower postoperative morphine consumption (median 5.5 vs 14 mg, P < .05), lower febrile morbidity rate (15% vs 45.8%, P < .05), and shorter hospital stay (median 4 vs 6 days, P < .001) and demonstrated a less intense stress response in terms of serum interleukin-6 (median 50.6 vs 73.9 pg/mL x hour x 10, P = .01), C-reactive protein (median 28.1 vs 44.7 mg/L x hour x 10(2), P = .005), cortisol (median 23.4 vs 27.2 mg/mL x hour x 10(3), P = .04), white blood cell count (median 59.5 vs 69.8 10(9)/L x hour x 10, P = .009), 24-hour urinary excretion of cortisol (median 34.8 vs 44.2 nmol/L x hour x 10(3), P = .02), and norepinephrine (median 80.8 vs 132.4 nmol/L x hour x 10(2), P = .001). No significant difference was detected in plasma glucose (median 41.5 vs 45.6 mmol/L x hour x 10, P = 6) and 24-hour urinary excretion of epinephrine (median 32.2 vs 34.1 nmol/L x hour x 10(2), P = .3). CONCLUSION: Laparoscopic hysterectomy is associated with a lower morbidity and a less intense stress response than abdominal hysterectomy for benign diseases.

Abdomen↗
PubMed1998

Treatment of hemoglobin Bart's hydrops with bone marrow transplantation.

A 21-month-old girl with hemoglobin Bart's hydrops received bone marrow transplantation (BMT) from a matched sibling. No major BMT-related complications developed. Hemoglobin levels remained greater than 10 gm/dl for 20 months without blood transfusion support despite the presence of residual host hemopoietic cells from 2 months after BMT. We suggest consideration of this therapeutic option for surviving patients.

Bone Marrow Transplantation↗
PubMed1998

Isolated testicular relapse after bone marrow transplant with total body irradiation and testicular boost in acute lymphoblastic leukemia.

A 7-year-old boy with Ph+ ALL received an allogeneic BMT in second remission. Conditioning included cyclophosphamide 60 mg/kg for 2 days, TBI 2 Gy twice daily for 3 days (12 Gy) and a single testicular boost of 4 Gy. He remained in hematological remission after BMT but developed isolated testicular relapse at 17 months. He underwent orchiectomy of the affected testis, 24 Gy testicular radiotherapy and systemic chemotherapy. He remains in remission 24 months after the testicular relapse. This is the first report of isolated testicular relapse which received a testicular irradiation boost included in the conditioning.

Bone Marrow Transplantation↗