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Biomedical subjects

P M Yuen

Publications and source records attributed to P M Yuen.

At least 19 recordsLinked to original sources
PubMed2007

Avoiding manual removal of placenta: evaluation of intra-umbilical injection of uterotonics using the Pipingas technique for management of adherent placenta.

BACKGROUND: Manual removal of placenta is performed in 1-3% of cases, and whilst a well established and relatively safe procedure, it is not without complications, which include infection, hemorrhage, uterine rupture, and occasional maternal death. METHODS: A three-arm randomized controlled trial of 50 IU Syntocinon (in 30 ml N saline) versus 800 mcg misoprostol (in 30 ml N saline) versus 30 ml N saline alone (control), injected into the placental bed via the umbilical vein using the Pipingas method. A group sequential research model (triangular test: PEST4) was adopted to minimize the sample size, as retained placenta is a relatively uncommon condition. RESULTS: No significant difference in the rate of manual removal was observed between the control and Syntocinon groups. On triggering the automatic stopping rule for this arm of the trial all subsequent cases recruited were allocated to receive either Syntocinon or misoprostol. After a total of 54 cases a significant reduction in manual removal of placenta was observed in the misoprostol group, triggering the automatic stopping rule and terminating the trial. CONCLUSION: Misoprostol (800 mcg) dissolved in 30 ml N saline and administered by intraumbilical injection using the Pipingas technique significantly reduces the need for manual removal for retained adherent placenta, whereas Syntocinon has similar effectiveness to injection of N saline alone.

Female↗
PubMed2006

A double-blind randomized controlled trial of oral misoprostol and intramuscular syntometrine in the management of the third stage of labor.

BACKGROUND: The aim of this study was to compare the efficacy and safety of oral misoprostol 400 mug with intramuscular syntometrine in the management of the third stage of labor. MATERIAL AND METHODS: This was a double-blind randomized controlled trial conducted in a tertiary care hospital. Three hundred and fifty-five women randomized to receive either oral misoprostol 400 mug or intramuscular syntometrine in the third stage of labor were studied. The change in hemoglobin level from before to 48 h after delivery, use of additional oxytocics and treatment related side effects were the main outcome measures. RESULTS: There were no significant differences between the two groups in terms of the change in hemoglobin level and mean blood loss. The incidence of shivering was significantly higher in the misoprostol group whilst that of vomiting was significantly higher in the syntometrine group. There were no differences in the incidence of nausea, headache, diarrhea and pyrexia between the two groups. CONCLUSION: Orally administered misoprostol at a dose of 400 mug is an acceptable alternative in preventing post-partum blood loss, as measured by the peri-partum change in hemoglobin level and was not associated with an increased incidence of side effects.

Administration, Oral↗
PubMed2004

Outcome in laparoscopic management of persistent adnexal mass during the second trimester of pregnancy.

BACKGROUND: This study evaluated the safety of laparoscopic management for persistent adnexal mass in the second trimester of pregnancy. METHODS: Between April 1994 and March 2003, 67 consecutive women underwent laparoscopic removal of adnexal masses that had persisted into the second trimester of pregnancy in an academic tertiary referral center. Operative complications, pregnancy, and labor outcomes were evaluated. RESULTS: The median gestation was 10.5 weeks (range, 5-25 weeks) at diagnosis and 16 weeks (range, 12-25 weeks) at the time of operation. Only two women required for conversion to laparotomy. Cystectomy was performed for 55 women, oophorectomy for 9 women and fenestration in 3 women. There were no intraoperative complications or major postoperative complications. No women were given tocolytic therapy, and none experienced uterine contractions. There was one spontaneous abortion 6 weeks after the operation, and one patent was lost to follow up. Of the remaining 65 women, the median gestation at delivery was 39 weeks (range, 33-42 weeks), and the median birthweight was 3,160 g (range, 2,220-4,200 g). CONCLUSIONS: Laparosocpic surgery for persistent adnexal masses in the second trimester of pregnancy is safe when performed by experienced surgeons.

Adnexal Diseases↗
PubMed2004

Torsion of a paraovarian myoma in a teenage woman.

Myomas are uncommon in adolescence and very rarely occur outside the uterus. Torsion of a paraovarian myoma in an 18-year-old woman was managed laparoscopically. Awareness of the condition and high index of suspicion are keys to early diagnosis and prompt intervention.

Adnexal Diseases↗
PubMed2002

A prospective randomized trial comparing patient-controlled sedation using propofol and alfentanil and physician-administered sedation using diazepam and pethidine during transvaginal ultrasound-guided oocyte retrieval.

BACKGROUND: This open label study compared the effectiveness of patient-controlled sedation (PCS), with physician-administered sedation (PAS) during transvaginal ultrasound-guided oocyte retrieval (TUGOR). METHODS: A total of 106 patients was randomized using a computer model to receive either PCS (n = 51) or PAS (n = 55). Intra-operative sedation and co-operation were measured on a 5-point scale while severity of pain, and doctor and patient satisfaction were assessed using a 100 mm visual analogue scale. Number of oocytes retrieved and fertilization, cleavage and clinical pregnancy rates were also recorded. RESULTS: Levels of sedation and co-operation were similar between groups. The pain score was higher in the PCS group during (mean +/- SD, 53 +/- 23 versus 35 +/- 24; P < 0.01) and 2 h after the procedure (29 +/- 27 versus 17 +/- 22; P < 0.05). Doctors were less satisfied with PCS than PAS (62 +/- 25 versus 71 +/- 26; P < 0.05) while patients were highly satisfied with both methods (76 +/- 23 versus 74 +/- 21; not significant). There were no oversedation or peri-operative complications. Fertility outcomes were similar. Patients tended to prefer PCS when given the choice of sedation method. CONCLUSION: Although PCS provides less analgesia then PAS during TUGOR, it is safe, satisfactory and accepted by patients.

Adult↗
PubMed2002

A randomised controlled trial of intramuscular syntometrine and intravenous oxytocin in the management of the third stage of labour.

OBJECTIVE: To compare the efficacy and safety of intravenous oxytocin with intramuscular syntometrine in the management of the third stage of labour. DESIGN: A prospective randomised trial. SETTING: A university teaching hospital. METHODS: A total of 991 women having a singleton pregnancy and vaginal delivery were randomised by a computer-generated number to receive either 1 ml syntometrine intramuscularly or 10 units of intravenous Syntocinon after delivery of the anterior shoulder of the fetus. MAIN OUTCOME MEASURES: Blood loss during delivery, rate of postpartum haemorrhage, need for repeated oxytocics, haemoglobin level before and 24 hours after delivery, duration of third stage, need for manual removal of placenta and sides effects including hypertension, nausea, vomiting, headache and chest pain. RESULTS: The use of intravenous oxytocin was associated with a reduction in postpartum blood loss (P < 0.001) but there was no difference in the risk of postpartum haemorrhage in the need for repeated oxytocic injections and the drop in peripartum haemoglobin level between the two groups. There was also no difference in the risk of prolonged third stage, or in the need for manual removal of placenta. The use of syntometrine was associated with a higher risk of hypertension (RR 2.39, 95% CI 1.00-5.70). Other side effects were mild in nature with no differences between the two groups. CONCLUSIONS: There are no important clinical differences in the effectiveness of intramuscular syntometrine and intravenous oxytocin for the prevention of postpartum blood loss. Intravenous oxytocin is less likely to cause hypertension.

Adult↗
PubMed2001

TEL/AML1 rearrangement and the prognostic significance in childhood acute lymphoblastic leukemia in Hong Kong.

The TEL/AML1 rearrangement has been implicated as an independent good prognostic factor in pediatric acute lymphoblastic leukemia (ALL). We examined TEL/AML1 using nested reverse-transcription polymerase chain reaction (RT-PCR) and correlated TEL/AML1 with cytogenetics and immunophenotypes in 75 consecutively analyzed Chinese children with ALL in Hong Kong. TEL/AML1 was detected in 17.9% (12/67) B-lineage ALL at diagnosis but not in 8 T-ALL children or in 34 adults with ALL. E2A/PBX1, MLL/AF4, and BCR/ABL were not found in TEL/AML1+ patients. Coexpression of cross-lineage antigens was associated with TEL/AML1 gene fusion (p = 0.032), with CD13 in 80% (4/5) TEL/AML1+ cohort. Chromosomal abnormalities were demonstrated in 50% of the TEL/AML1+ ALL; however, a cryptic t(12;21) was not detected in these cases. Hyperdiploidy of 47-48 chromosomes was encountered in 25%. Deletion of 12p resulting in the loss of the normal allele of TEL and nonspecific del(6q) were noted in 8% (1/12) and 25% (3/12) of the TEL/AML1+ children, respectively. Rapid clearance of TEL/AML1 was noted in 50% of the patients on completion of the induction therapy; however, 16.7% (2/12) TEL/AML1+ ALL relapsed at a mean of 48.6 months from diagnosis (25 months off-therapy). The incidence of relapses of TEL/AML1+ ALL was comparable to that at diagnosis in B-lineage ALL (14.3% [2/14] vs. 17.9% [12/67], p > 0.05). The relapse rate in TEL/AML1+ ALL was similar to that of TEL/AML1- ALL (16.7% [2/12] vs. 20.6% [13/63], p > 0.05). The duration of first complete remission in TEL/AML1+ ALL was significantly longer as compared to TEL/AML1- ALL (mean [range] in month: 48.6 [47.2 - 50] vs 14.6 [2.9 - 42.3], p < 0.0001). Irrespective of TEL/AML1 rearrangement, the probabilities of the five-year overall survival and the event-free survival of patients were comparable (overall survival: 100% vs. 72.3%, p = 0.166 and event-free survival: 60% vs. 56.2%, p = 0.343). Our data would not suggest a less aggressive treatment regimen for TEL/AML1+ ALL.

Adolescent↗
PubMed2001

Platelet-derived growth factor enhances granulopoiesis via bone marrow stromal cells.

Platelet-derived growth factor (PDGF), a growth factor for connective tissue cells, stimulates erythropoiesis and megakaryocytopoiesis in vitro but the effect of PDGF on granulocyte proliferation remains unknown. The effect of the recombinant human PDGF-BB isoform on granulopoiesis was investigated in this study. The results show that PDGF significantly stimulated murine colony-forming unit-granulocyte-monocyte (CFU-GM) proliferation in a dose-dependent manner (1 to 100 ng/mL) using murine bone marrow cells (n = 4). Maximum stimulation was obtained with 50 ng/mL of PDGF (P < .01). The effect of PDGF on murine CFU-GM proliferation was compared with that of interleukin (IL)-3, IL-6, granulocyte-monocyte colony-stimulating factor (GM-CSF), and acidic fibroblast growth factor (aFGF) at their optimal doses. The stimulating activity of PDGF was higher than that of aFGF but lower than that of IL-3, IL-6, or GM-CSF. There is no synergistic effect between PDGF and IL-3 or IL-6, but a significant enhancing effect was observed in IL-3 plus IL-6. PDGF also stimulated the growth of CFU-GM with CFU-megakaryocyte in the presence of bone marrow stromal cells. We also found that PDGF had similar a effect on human CFU-GM proliferation using bone marrow mononuclear cells (MNC). However, the increase in PDGF-stimulated CFU-GM proliferation was inhibited by anti-GM-CSF, anti-IL-3, and anti-IL-6 antibodies (n = 4), suggesting that endogenously produced GM-CSF, IL-3, and IL-6 may play a role in the PDGF-induced CFU-GM proliferation. Furthermore, PDGF (1 to 100 ng/mL) did not show any effect on CFU-GM proliferation when replacing bone marrow MNC with immunomagnetic selection-enriched CD34+ cells from human cord blood (n = 5; purity, 91% +/- 6.5%). This study indicates that PDGF may indirectly enhance CFU-GM proliferation by inducing the bone marrow stromal cells to produce GM-CSF, IL-3, or IL-6.

Adult↗
PubMed2001

Regulation of human oviductin mRNA expression in vivo.

OBJECTIVE: To examine changes in oviductin mRNA expression in oviductal mucosal tissue from fertile women throughout an ovulatory cycle. DESIGN: Semiquantitative reverse-transcriptase-polymerase chain reaction (RT-PCR) analysis of oviductin mRNA. SETTING: University-based obstetrics and gynecology department. SUBJECT(S): Twenty women undergoing laparoscopy for tubal sterilization or hysterectomy for uterine fibroids. INTERVENTION(S): The mucosal layer was isolated from the oviduct tissue, and semiquantitative RT-PCR was performed. MAIN OUTCOME MEASURE(S): The relationship between serum estradiol, luteinizing hormone, and progesterone concentrations and the expression of oviductin mRNA. RESULT(S): There was a significant positive correlation between serum estradiol and luteinizing hormone concentrations and oviductin mRNA expression. There was a significant inverse correlation between serum progesterone concentrations and oviductin mRNA expression. CONCLUSION(S): Little is known about the regulation of human oviductin. This study was the first to examine the relationship between oviductin mRNA expression and serum estradiol and luteinizing hormone and progesterone concentrations in fertile women. Estradiol and luteinizing hormone both have a stimulatory effect on oviductin mRNA in humans, however, it is difficult to determine whether the effects are independent of one another, as the luteinizing hormone surge is dependent on the estradiol increase. Progesterone shows a clear inhibitory effect on oviductin mRNA.

Adult↗
PubMed2001

Randomized double-masked comparison of radially expanding access device and conventional cutting tip trocar in laparoscopy.

OBJECTIVE: To compare postoperative wound pain associated with the radially expanding access device and the conventional disposable cutting-tip trocar. METHODS: Our randomized, double-masked, self-controlled study involved 34 women scheduled for laparoscopic adnexal surgery. In each, a 10-mm radially expanding access device was inserted laterally on one side of the lower abdomen and a size-matched disposable cutting-tip trocar was placed on the other side, using random assignment. Postoperative pain for each studied wound and patient satisfaction toward the wounds were assessed using a visual analog scale. Any bleeding complication associated with insertion of the trocar was also recorded. RESULTS: The radially expanding access device was associated with significant reduction in severity (median 1.4 versus 5.0, P <.001) and duration (median 11 versus 21 days, P <.001) of postoperative wound pain, shorter wound scars (14 versus 17 mm, P <.001), a lower incidence of wound induration (0 versus 9, P <.01), and a higher patient satisfaction (median 9.7 versus 6.2, P <.001). There were four inferior epigastric artery injuries, all at the conventional trocar wound. CONCLUSION: The radially expanding access device was associated with less postoperative wound pain and more patient satisfaction than the conventional cutting-tip trocar.

Adnexal Diseases↗
PubMed2001

Cord blood collection before and after placental delivery: levels of nucleated cells, haematopoietic progenitor cells, leukocyte subpopulations and macroscopic clots.

The number of nucleated cells infused into the recipient of a cord blood (CB) transplant has emerged as the most important factor affecting the probability and speed of engraftment. At present, there is no international consensus on the procedure of CB collection in the maternity ward. In order to maximise the yield of viable cells in a CB unit, we aimed to investigate the efficiency of CB collection, with respect to the time of delivery of the placenta. We analysed stem and progenitor cells in terms of CD34+ cell content and colony-forming activities, lymphocyte subpopulations and the presence of macroscopic clots in 93 paired CB samples, collected before and after the delivery of the placenta. Our results demonstrated that the median concentrations of nucleated cells and total colony-forming unit (CFU) were significantly lower in CB collected after placenta delivery by 9.5% (P < 0.001) and 11.6% (P = 0.015), respectively, when compared to their counterparts collected before placental delivery. A reduction of granulocytes (P < 0.001), monocytes (P < 0.001) and CD19+ B lymphocytes (P = 0.031) was observed, with no significant change in the proportion of T cell subsets (CD4+, CD8+ cells) or activated T cells (CD25+, CD45RO+ cells) in samples collected after placenta delivery. The incidence of macroscopic clots was also higher in these samples (31% vs 1%, P < 0.001). The reduction of stem and progenitor cells correlated significantly with that of major cell populations, indicating a general cell loss, possibly due to clotting activities developed with time. Our study has documented strong evidence for recommending the collection of CB before the delivery of the placenta.

Blood Cell Count↗
PubMed2001

A fludarabine-based conditioning regimen for severe aplastic anemia.

Graft rejection is a common problem after alternative donor transplantation for patients with refractory severe aplastic anemia (SAA). Intensification of the conditioning regimen, with the inclusion of irradiation, has often been advocated to combat this problem. With this approach engraftment rate improved, but the incidence of transplant-related complications is also increased, resulting in little change in the overall outcome. We investigated the use of the combination of fludarabine, cyclophosphamide and anti-thymocyte globulin as the conditioning regimen in five multiply-transfused SAA patients. Three patients received an HLA one-antigen disparate related donor transplant, while two patients were given marrow from matched, unrelated donors. The regimen was well tolerated, with only grade I toxicity encountered. With a median follow-up of 9 months, all patients are alive with complete donor chimerism. We conclude that fludarabine may be used in place of irradiation to augment the conditioning regimen of cyclophosphamide and anti-thymocyte globulin for alternative donor transplantation in children with SAA.

Anemia, Aplastic↗
PubMed2001

Platelet-derived growth factor enhances ex vivo expansion of megakaryocytic progenitors from human cord blood.

Infusion of ex vivo expanded megakaryocytic (MK) progenitor cells is a strategy for shortening the duration of thrombocytopenia after haematopoietic stem cell transplantation. The cell dose after expansion has emerged as a critical factor for achieving the desired clinical outcomes. This study aimed to establish efficient conditions for the expansion of the MK lineage from enriched CD34(+) cells of umbilical cord blood and to investigate the effect of platelet-derived growth factor (PDGF) in this system. Our results demonstrated that thrombopoietin (TPO) alone produced a high proportion of CD61(+)CD41(+) cells but a low total cell count and high cell death, resulting in an inferior expansion. The addition of interleukin-1 beta (IL-1 beta), Flt-3 ligand (Flt-3L) and to a lesser extent IL-3 improved the expansion outcome. The treatment groups with three to five cytokines produced efficient expansions of CFU-MK up to 400-fold with the highest yield observed in the presence of TPO, IL-1 beta, IL-3, IL-6 and Flt-3L. CD34(+) cells were expanded by five to 22-fold. PDGF improved the expansion of all cell types with CD61(+)CD41(+) cells, CFU-MK and CD34(+) cells increased by 101%, 134% and 70%, respectively. On day 14, the CD61(+) population consisted of diploid (86.5%), tetraploid (11.8%) and polyploid (8N--32N; 1.69%) cells. Their levels were not affected by PDGF. TPO, IL-1 beta, IL-3, IL-6, Flt-3L and PDGF represented an effective cytokine combination for expanding MK progenitors while maintaining a moderate increase of CD34(+) cells. This study showed, for the first time, that PDGF enhanced the ex vivo expansion of the MK lineage, without promoting their in vitro maturation. PDGF might be a suitable growth factor to improve the ex vivo expansion of MK progenitors for clinical applications.

Antigens, CD↗
PubMed2001

Prevalence and genotype distribution of TT virus in various specimen types from thalassaemic patients.

Peripheral blood mononuclear cells (PBMC), plasma, saliva and urine samples were collected from 50 thalassaemic patients for TT virus (TTV) detection by two sets of PCR. The set B nested PCR was more sensitive than the widely used NG hemi-nested PCR with TTV positive rates approximately PBMC: 98% vs. 70%; plasma: 92% vs. 66%; saliva: 62% vs. 22%; urine: 22% vs. 6%. All 50 patients had TTV detected in one or more specimens, with 16% of patients being positive in all four specimen types: 40% positive in PBMC, plasma and saliva; 30% positive in PBMC and plasma. In 82 NG hemi-nested PCR-positive samples TTV genotype was identified, 68.3% had a single genotype, 25.6% had multiple genotypes and 6.1% were uncharacterized. The positive rates for genotypes by specimen were: G1 (36/82), G2 (49/82), G3 (2/82), G4 (7/82), G5 (1/82) and G6 (3/82). Among the 42 patients for whom the genotype was examined, 42.9% had single-type infection, 45.2% had co-infections and 11.9% had uncharacterized genotypes. Sixteen of them had TTV detected both in PBMC and plasma with seven having identical genotypes in both samples. Eight patients had TTV detected in PBMC, plasma and saliva; two of them harboured identical genotypes in all three samples. The results indicate that, apart from hepatocytes, PBMC is a major cell type for TTV infection occurs. Shedding of TTV in urine and saliva is common and may have a significant role in nonblood-borne transmission among the general population. TTV-infected patients often harbour multiple genotypes suggesting infection with one genotype does not necessarily confer protection against the others. No correlation between TTV infection and liver dysfunction was observed.

DNA Virus Infections↗
PubMed2001

Haematopoietic stem and progenitor cells in human term and preterm neonatal blood.

BACKGROUND AND OBJECTIVES: Whilst cord blood (CB) contains a significant number of haematopoietic stem and progenitor cells suitable for bone marrow transplantation, levels of these cells are very low in the adult circulation. In previous studies, we demonstrated that stem and progenitor cells are present in neonatal blood (NB) and reported the first sibling transplant using a combination of CB and NB for a patient with beta-thalassaemia major. However, our preliminary data showed that the number of CD34+ cells decreased rapidly in the peripheral blood of neonates soon after birth. To further investigate the mechanism of the change of stem and progenitor cells in NB, we measured the steady-state levels of CD34+ cells, early progenitor subsets and the expression of adhesion molecules, in term and preterm neonates. MATERIALS AND METHODS: NB was collected serially from infants at 2, 4, 6, 8, 24 and 48 h after birth and was analysed by three-colour flow cytometry. RESULTS: Our results demonstrated that the number of CD34+ cells rapidly decreased in term NB, particularly during the first 2-6 h of life, by 29.2 +/- 5.55% (P = 0.0003) in absolute counts/ml. A decrease was observed in all subsets of CD34+ cells studied, including the CD33+, CD71+, CD62L+ and CD49d+ populations. In contrast, the CD34+ cell number increased in preterm infants in the first 8 h of life, before starting to decrease. Significant inverse correlations were observed between gestational age and levels of CD34+ cells (P = 0.0065, 4-h collection time-point). CONCLUSION: Our study suggests that changes in the levels of CD34+ stem and progenitor cells in NB might be triggered by parturition and affected by the gestational age. Our findings confirmed that if targeted as a supplementary source of stem and progenitor cells to CB for transplantation, NB should be collected as soon as possible after birth.

Antigens, CD34↗
PubMed2001

Severe chronic neutropenia in Chinese children in Hong Kong.

OBJECTIVE: Severe chronic neutropenia (SCN) is a rare and heterogeneous disorder in children. The epidemiology, clinical features and outcomes of SCN in Chinese children were reviewed. METHODOLOGY: A retrospective analysis of case records was undertaken for 18 children with SCN managed during a 12-year period in a university teaching hospital in Hong Kong. RESULTS: The median (range) age of the patients at initial presentation was 6.5 months (4 days-19 months). The initial and lowest median absolute neutrophil counts (ANC) were 0.29 x 109 /L and 0.06 x 109 /L, respectively. Patients with congenital SCN had significantly fewer neutrophils in peripheral blood at diagnosis. Only five subjects received granulocyte colony-stimulating factor (G-CSF) treatment. All children were free from serious infection on follow up for 51 months. Only one child suffered from long-term infection-related morbidity. One patient with chronic neutropenia was subsequently shown to have common variable immunodeficiency. CONCLUSIONS: Most children with SCN in our series had favourable clinical outcomes. Our results support the recommendation that G-CSF should be used only in those with recurrent or severe infections.

China↗