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Biomedical subjects

E Ng

Publications and source records attributed to E Ng.

At least 19 recordsLinked to original sources
PubMed2005

Heparin for prolonging peripheral intravenous catheter use in neonates.

BACKGROUND: Peripheral intravenous (PIV) catheters are widely used in modern medical practice. However, mechanical or infectious complications often necessitate their removal and/or replacement. Heparin has been shown to be effective in prolonging the patency of peripheral arterial catheters and central venous catheters, but may result in life threatening complications, especially in preterm neonates. OBJECTIVES: The primary objective was to determine the effectiveness of heparin versus placebo or no treatment on duration of PIV catheter patency, defined as number of hours of catheter use. The secondary objectives were to assess the effects of heparin on catheter blockage, phlebitis or thrombophlebitis, catheter related sepsis, and complications including abnormality of coagulation profile, allergic reactions to heparin, heparin induced thrombocytopenia, intraventricular/intracranial hemorrhage and mortality. SEARCH STRATEGY: A literature search was performed using the following databases: MEDLINE (1966-February 2005), EMBASE (1980-February 2005), CINAHL (1982-February 2005), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2005), and abstracts from the annual meetings of the Society for Pediatric Research, American Pediatric Society and Pediatric Academic Societies published in Pediatric Research (1991-2004). No language restrictions were applied. SELECTION CRITERIA: Randomized or quasi-randomized trials of heparin administered as flush or infusion versus placebo or no treatment were included. Studies which included a neonatal population and reported on at least one of the outcomes were included. DATA COLLECTION AND ANALYSIS: The methodological quality of the studies was assessed using criteria for blinding of randomization, blinding of intervention, completeness of follow-up and blinding of outcome assessment. Data on relevant outcomes were extracted and the effect size was estimated by calculating WMD (weighted mean difference, 95%CI), RR (relative risk, 95% CI) and RD (risk difference, 95% CI). MAIN RESULTS: Ten eligible studies were identified. Heparin was administered either as a flush solution, or as an additive to the total parenteral nutrition solution. Five studies reported data on the duration of use of the first catheter. Two of these studies found no statistically significant effect of heparin; two studies showed a statistically significant increase and one study showed a statistically significant decrease in the duration of PIV catheter use in the heparin group. The results were not combined for meta-analysis due to significant heterogeneity of the treatment effect (p < 0.01). In addition, there were marked differences between the studies in terms of the methodological quality, the dose, the timing, the route of administration of heparin and the outcomes reported. From a limited number of studies, there were no significant differences between the heparin and the placebo/no treatment groups in the risks of infiltration, phlebitis and intracranial hemorrhage. AUTHORS' CONCLUSIONS IMPLICATIONS FOR PRACTICE: The effect of heparin on the duration of peripheral intravenous catheter use varied across the studies. Because of clinical heterogeneity and heterogeneity in treatment effect, recommendations for heparin use in neonates with PIV catheters cannot be made. IMPLICATIONS FOR RESEARCH: There are insufficient data concerning the effect of heparin for prolonging PIV catheter use in neonates. Further research on the effectiveness, the optimal dose, and the safety of heparin is required.

Anticoagulants↗
PubMed2005

A pilot study to compare the use of the Excorim staphylococcal protein immunoadsorption system and IVIG in chronic inflammatory demyelinating polyneuropathy.

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune mediated neuropathy responding to immunomodulation with IVIG or plasma exchange (PE). We tested the efficacy and safety of selective immunoglobulin removal by Excorim immunoadsorption (IA) in a pilot trial in CIDP patients randomized to monthly IA or IVIG treatments for 6 months. Response rates at 2 and 6 months were greater with IA due to longer disease duration and greater disability at baseline in the patients receiving IVIG. IA appears to be a safe and efficacious therapy for patients with CIDP, but an appropriately powered clinical trial with stratification for disease duration is required.

Adolescent↗
PubMed2005

Recent enhancements to the MARS15 code.

The MARS code is under continuous development and has recently undergone substantial improvements that further increase its reliability and predictive power in numerous shielding, accelerator, detector and space applications. The major developments and new features of the MARS15 (2004) version described in this paper concern an extended list of elementary particles and arbitrary heavy ions and their interaction cross sections, inclusive and exclusive nuclear event generators, module for modelling particle electromagnetic interactions, enhanced geometry and histogramming options, improved MAD-MARS Beam Line Builder, enhanced graphical user interface and an MPI-based parallelisation of the code.

Algorithms↗
PubMed2002

Heparin for prolonging peripheral intravenous catheter use in neonates.

BACKGROUND: Peripheral intravenous (PIV) catheters are widely used in modern medical practice. However, mechanical or infectious complications often necessitate their removal and/or replacement. Heparin has been shown to be effective in prolonging the patency of peripheral arterial catheters and central venous catheters, but may result in life threatening complications, especially in preterm neonates. OBJECTIVES: The primary objective was to determine the effectiveness of heparin versus placebo or no treatment on duration of PIV catheter patency, defined as number of hours of catheter use. The secondary objectives were to assess the effects of heparin on catheter blockage, phlebitis or thrombophlebitis, catheter related sepsis, and complications including abnormality of coagulation profile, allergic reactions to heparin, heparin induced thrombocytopenia, intraventricular/intracranial hemorrhage and mortality. SEARCH STRATEGY: A literature search was performed using the following databases: MEDLINE (1966-December 2001), EMBASE (1980-December 2001), CINAHL (1982-December 2001), Cochrane Controlled Trials Register (The Cochrane Library, Issue 4, 2001), and abstracts from the annual meetings of the Society for Pediatric Research, American Pediatric Society and Pediatric Academic Societies published in Pediatric Research (1991-2001). No language restrictions were applied. SELECTION CRITERIA: Randomized or quasi-randomized trials of heparin administered as flush or infusion versus placebo or no treatment were included. Studies which included a neonatal population and reported on at least one of the outcomes were included. DATA COLLECTION AND ANALYSIS: The methodological quality of the studies was assessed using criteria for blinding of randomization, blinding of intervention, completeness of follow-up and blinding of outcome assessment. Data on relevant outcomes were extracted and the effect size was estimated by calculating WMD (weighted mean difference, 95%CI), RR (relative risk, 95% CI) and RD (risk difference, 95% CI). MAIN RESULTS: Eight eligible studies were identified. Heparin was administered either as a flush solution or as an additive to the total parenteral nutrition solution. Five studies reported data on the duration of use of the first catheter. Two of these studies found no statistically significant effect of heparin; two studies showed a statistically significant increase and one study showed a statistically significant decrease in the duration of PIV catheter use in the heparin group. The results were not combined for meta-analysis due to significant heterogeneity of the treatment effect (p<0.01). In addition, there were marked differences between the studies in terms of the methodological quality, the dose, the timing, the route of administration of heparin and the outcomes reported. From a limited number of studies, there were no significant differences between the heparin and the placebo/no treatment groups in the risks of infiltration, phlebitis and intracranial hemorrhage. REVIEWER'S CONCLUSIONS IMPLICATIONS FOR PRACTICE: The effect of heparin on the duration of peripheral intravenous catheter use varied across the studies. Because of clinical heterogeneity and heterogeneity in treatment effect, recommendations for heparin use in neonates with PIV catheters cannot be made. IMPLICATIONS FOR RESEARCH: There are insufficient data concerning the effect of heparin for prolonging PIV catheter use in neonates. Further research on the effectiveness, the optimal dose, and the safety of heparin is required.

Anticoagulants↗
PubMed2001

Randomised comparison of three methods of administering a screening questionnaire to elderly people: findings from the MRC trial of the assessment and management of older people in the community.

OBJECTIVE: To compare three different methods of administering a brief screening questionnaire to elderly people: post, interview by lay interviewer, and interview by nurse. DESIGN: Randomised comparison of methods within a cluster randomised trial. SETTING: 106 general practices in the United Kingdom. PARTICIPANTS: 32 990 people aged 75 years or over registered with participating practices. MAIN OUTCOME MEASURES: Response rates, proportion of missing values, prevalence of self reported morbidity, and sensitivity and specificity of self reported measures by method of administration of questionnaire for four domains. RESULTS: The response rate was higher for the postal questionnaire than for the two interview methods combined (83.5% v 74.9%; difference 8.5%, 95% confidence interval 4.4% to 12.7%, P<0.001). The proportion of missing or invalid responses was low overall (mean 2.1%) but was greater for the postal method than for the interview methods combined (4.1% v 0.9%; difference 3.2%, 2.7% to 3.6%, P<0.001). With a few exceptions, levels of self reported morbidity were lower in the interview groups, particularly for interviews by nurses. The sensitivity of the self reported measures was lower in the nurse interview group for three out of four domains, but 95% confidence intervals for the estimates overlapped. Specificity of the self reported measures varied little by method of administration. CONCLUSIONS: Postal questionnaires were associated with higher response rates but also higher proportions of missing values than were interview methods. Lower estimates of self reported morbidity were obtained with the nurse interview method and to a lesser extent with the lay interview method than with postal questionnaires.

Aged↗
PubMed2001

Comparative genomics of Listeria species.

Listeria monocytogenes is a food-borne pathogen with a high mortality rate that has also emerged as a paradigm for intracellular parasitism. We present and compare the genome sequences of L. monocytogenes (2,944,528 base pairs) and a nonpathogenic species, L. innocua (3,011,209 base pairs). We found a large number of predicted genes encoding surface and secreted proteins, transporters, and transcriptional regulators, consistent with the ability of both species to adapt to diverse environments. The presence of 270 L. monocytogenes and 149 L. innocua strain-specific genes (clustered in 100 and 63 islets, respectively) suggests that virulence in Listeria results from multiple gene acquisition and deletion events.

Adaptation, Physiological↗
PubMed2001

Head-up tilt test without intravascular cannulation in children and adolescents.

Previous studies of head-up tilt test have shown that testing at high degrees lacks specificity in children. We suspected that the high false positive rate might be related to the intravascular catheter and other maneuvers incorporated in the test and therefore studied the sensitivity and specificity of standing and HUT at 80 degrees without any invasive procedure and other maneuvers in children and adolescents. Twenty three patients (11.8+/-2.7 years) with recurrent typical neurally mediated syncope and 35 normal control children (11.6+/-3.0 years) underwent motionless standing for 15 min and tilting to 80 degrees for 30 min. Continuous finger arterial pressure monitoring and ECG were performed during the test. Eight (35%) of the 23 patients developed symptoms of near syncope during motionless standing. Thirteen (57%) of them had positive results at 80 degrees tilting for 30 min. The symptoms of syncope were not always corresponding to excessive haemodynamic changes. None of the controls developed any symptoms or excessive hemodynamic changes. Without intravascular instrumentation and other autonomic maneuvers, active motionless standing or HUT at 80 degrees for 30 min is highly specific but of limited sensitivity for the investigation of vasovagal syncope.

Adolescent↗
PubMed2001

N-terminal fatty-acylation of sonic hedgehog enhances the induction of rodent ventral forebrain neurons.

The adult basal ganglia arise from the medial and lateral ganglionic eminences, morphologically distinct structures found in the embryonic telencephalon. We have previously shown that temporal changes in sonic hedgehog (Shh) responsiveness determine the sequential induction of embryonic neurons that populate the medial and lateral ganglionic eminences. In this report, we show that Shh-mediated differentiation of neurons that populate the lateral ganglionic eminence express different combinations of the homeobox-containing transcription factors Dlx, Mash1 and Islet 1/2. Furthermore, we show that N-terminal fatty-acylation of Shh significantly enhances its ability to induce the differentiation of rat E11 telencephalic neurons expressing Dlx, Islet 1/2 or Mash1. Recent evidence indicates that in utero injection of the E9.5 mouse forebrain with retroviruses encoding wild-type Shh induces the ectopic expression of Dlx2 and severe deformities in the brain. In this report, we show that Shh containing a mutation at the site of acylation prevents either of these phenotypes. These results suggest that N-terminal fatty-acylation of Shh may play an important role in Shh-dependent signaling during rodent ventral forebrain formation.

Animals↗
PubMed2001

Provision of phenotype-matched blood units: no need for pre-transfusion antibody screening.

BACKGROUND AND OBJECTIVES: The Hong Kong government is planning to introduce an electronic smart identity card for all seven million citizens in 2003. If the smart card contains the full red cell phenotype/genotype of the individual, it may be possible to transfuse phenotype-matched blood units without pre-transfusion antibody screening. We conducted a feasibility study. DESIGN AND METHODS: Red cell phenotype was determined for 407 donor blood units and 493 patients for whom an antibody screen had been ordered. The computer program selected phenotype-matched blood from the donor stock for the patients according to actual transfusion request. For patients with a positive antibody screen, full crossmatching was carried out with the computer-selected phenotype units. The frequencies of the various red cell phenotypes in the population were calculated from Red Cross data of antigen frequencies. The probabilities of finding at least one unit of phenotype-matched blood from a 300-unit hospital stock and a 4,000-unit Red Cross stock were determined for each phenotype. Cost analysis was performed. RESULTS: Ninety-two out of 493 patients received a total of 395 blood units. The required number of phenotype-matched blood units could be found for 92 patients using a 300-unit pool and for all patients using a 4,000-unit pool. We calculated that phenotype-matched blood could be provided for more than 98% of patients without antibody screening. The total cost of the project is US$ 98 million with potential savings of US$ 14 million per year. INTERPRETATION AND CONCLUSIONS: It is feasible and cost-effective to transfuse patients with phenotype-matched blood without antibody screening using a smart card system.

Blood Group Antigens↗
PubMed2000

Yeast cytosine deaminase improves radiosensitization and bystander effect by 5-fluorocytosine of human colorectal cancer xenografts.

The efficacy of cancer gene therapy using bacterial cytosine deaminase (bCD)/5-fluorocytosine (5-FC) enzyme/prodrug strategy is limited by the inefficiency of cytosine deaminase (CD)-catalyzed conversion of 5-FC into 5-fluorouracil (5-FU). We have shown previously that yeast CD (yCD) is more efficient at the conversion of 5-FC than bCD. In the current study, we hypothesized that the increased production of 5-FU by yCD would enhance the efficacy of the CD/5-FC treatment strategy by increasing the bystander effect as well as the efficacy of radiotherapy because of the radiosensitizing capacity of 5-FU. To test this hypothesis, we generated stable HT29 human colon cancer cell lines expressing either bCD (HT29/bCD) or yCD (HT29/yCD). The amount of 5-FU produced in HT29/yCD tumors after a single injection of 5-FC (1000 mg/kg, i.p.) was 15-fold higher than that produced in HT29/bCD tumors. In tumor-bearing nude mice, the average minimum relative tumor size (compared with pretreatment values) of HT29/bCD tumors treated with 5-FC and radiation (500 mg/kg i.p. and 3 Gy, 5 days a week for 2 weeks) was 0.55+/-0.1, compared with 0.01+/-0.01 in HT29/yCD tumors (P = 0.002). Moreover, an increased cytotoxic and radiosensitizing effect of 5-FC on bystander cells was observed in vitro and in vivo when yCD was expressed in HT29 cells instead of bCD. In mice bearing HT29 tumors containing 10% HT29/yCD cells, the combined treatment resulted in a minimum tumor size of 0.20+/-0.07 compared with 0.60+/-0.1 in 10% HT29/bCD cells (P < 0.001). These results demonstrate that the use of yCD in the CD/5-FC strategy has a high potential to improve the therapeutic outcome of combined gene therapy and radiotherapy in cancer patients.

Animals↗
PubMed2000

Erythromycin for feeding intolerance in preterm infants.

BACKGROUND: Functional immaturity of gastointestinal motility predisposes preterm infants to feeding intolerance. Motilin, a gastrointestinal peptide, stimulates propagative contractile activity during phase III of the migratory motor complex in the interdigestive state. Erythromycin (EM) is a motilin agonist with prokinetic effect at low doses (1-3mg/kg). OBJECTIVES: To evaluate the effectiveness of EM in promoting gastrointestinal motility in preterm infants with feeding intolerance and assess clinically significant adverse effects associated with its use. SEARCH STRATEGY: Systematic literature search in accordance with the Cochrane Neonatal Collaborative Review Group search strategy. Randomized and quasi-randomized controlled trials of EM use, at any dose, in preterm infants to promote gastrointestinal motility were identified by searching MEDLINE, EMBASE, CINAHL, the Cochrane Library, reference lists of published studies, personal files, and abstracts published in Pediatric Research. SELECTION CRITERIA: Randomized controlled trials of oral or intravenous EM use at dose range of 3 to 12 mg/kg/day in preterm infants less than or equal to 36 weeks gestational age with feeding tolerance were included in this review. DATA COLLECTION AND ANALYSIS: Data regarding the primary clinical outcome of days to achieve full enteral feeding were compared among studies. Data on secondary outcomes including adverse effects associated with the use of EM (diarrhea, nosocomial infections, cardiac arrhythmias, or theophylline toxicity), duration of parenteral nutrition, weight gain, incidence of necrotizing enterocolitis (NEC), hypertrophic pyloric stenosis, and length of hospital stay were assessed. MAIN RESULTS: Two randomized controlled studies of EM use in preterm infants for improving gastrointestinal motility were identified. Since both studies involved preterm infants treated with EM at dose >12mg/kg/day at commencement of feeding, they did not meet inclusion criteria defined a priori for this review. There was no statistically significant difference in the incidence of NEC (RR 0.59, 95%CI 0.11, 3.01; RD -0.021, 95%CI -0. 087, 0.045). No statistically significant difference was noted in days to achieve full enteral feeds, length of hospital stay, and adverse events between groups. REVIEWER'S CONCLUSIONS: EM at antimicrobial doses may not be effective in preterm infants with feeding intolerance. Further studies are needed to determine whether EM in lower doses is effective as a prokinetic agent in such infants.

Anti-Bacterial Agents↗
PubMed2000

Intravenous midazolam infusion for sedation of infants in the neonatal intensive care unit.

BACKGROUND: The need for sedation for neonates undergoing uncomfortable procedures in the neonatal intensive care unit (NICU) has often been overlooked. Proper sedation may reduce stress and avoid complications during procedures such as mechanical ventilation. Midazolam is a short acting benzodiazepine that has been increasingly used in the NICU. However, the effectiveness of intravenous midazolam as a sedative in neonates has not been systematically evaluated. OBJECTIVES: To determine whether intravenous midazolam infusion is an effective sedative, as evaluated by behavioural and/or physiologic measurements, for critically ill neonates undergoing intensive care, and to assess clinically significant short and long term adverse effects associated with its use. SEARCH STRATEGY: Literature search according to the Cochrane Neonatal Collaborative Review Group search strategy. Randomized and quasi-randomized controlled trials of intravenous midazolam use in neonates were identified by searching MEDLINE, EMBASE, the Cochrane Controlled Trials Register, reference lists of published studies, personal files, and abstracts published in Pediatric Research from 1990-1999. SELECTION CRITERIA: Randomized controlled trials of intravenous midazolam infusion in infants </= 28 days of age for sedation during mechanical ventilation or radiologic investigations were selected for review. Studies on midazolam use as an anesthetic or an anticonvulsant were excluded. Studies involving neonates and older infants and children were excluded if data for neonates could not be extracted. DATA COLLECTION AND ANALYSIS: Data regarding the primary outcome of level of sedation (as evaluated by behavioural scales or physiologic parameters) were abstracted. Secondary outcomes including intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), death within 28 days of age, adverse effects associated with midazolam (hemodynamic and neurologic), days of ventilation, days of supplemental oxygen use, pneumothorax, length of NICU stay, and long term neurodevelopmental outcome were assessed. When appropriate, meta-analyses were performed using relative risk (RR), risk difference (RD), along with their 95% confidence intervals (95% CI) for categorical variables and weighted mean difference (WMD) for continuous variables. MAIN RESULTS: Two trials were eligible for inclusion in the review. Data on level of sedation from the two trials could not be combined because of differences in tools used to measure sedation levels. One study (Jacqz-Aigrain 1994) showed statistically a significant higher level of sedation in the midazolam group compared to the placebo group. The other study (Anand 1999) comparing midazolam to morphine and placebo found no statistically significant difference in sedation level among the three groups, but statistically significantly higher level of sedation was found in the midazolam group compared with the placebo group during the treatment infusion. However, since the sedation scales used in both studies have not been validated in preterm infants, the effectiveness of midazolam as a sedative in this population could not be ascertained based on the findings of these two studies. In the study by Jacqz-Aigrain (1994), blood pressures were statistically significantly lower in the midazolam group than in the placebo group on days 1 and 2, although there was no statistically significant difference in the incidence of hypotension requiring albumin or vasoactive drugs between groups. The study by Anand (1999) showed a statistically significant higher incidence of adverse neurologic events (death, grade III-IV IVH, PVL) in the midazolam group compared with the other groups. In addition, the midazolam group had a statistically significantly longer duration of NICU stay compared to the placebo group (WMD 5.4 days, 95%CI 0.4, 10.5). (ABSTRACT TRUNCATED)

Humans↗
PubMed2000

Improvement in transfusion safety using a specially designed transfusion wristband.

Fatal haemolytic transfusion reaction due to ABO incompatibility occurs mainly as a result of clerical error. A blood sample drawn from the wrong patient and labelled as another patient's will not be detected by the blood bank unless there is a previous ABO grouping result. We report here the detection of such clerical error by the use of a specially designed transfusion wristband. The wristband has the following special features: (i) once attached, it cannot be removed except by cutting; (ii) it has a pocket containing a transfusion label; (iii) a unique transfusion barcode is printed on each transfusion label and the corresponding wristband simultaneously by computer technology; (iv) a transfusion label removed from the wristband after attachment to the patient has a characteristic tear-mark distinguishing it from one removed prior to attachment. The blood bank only accepted those specimens bearing the tear-marked transfusion labels. All blood units for this patient were labelled with this unique transfusion code together with the patient's details. The nurses counter-checked the transfusion code on the blood units against the transfusion code on the patient's transfusion wristband prior to transfusion. If the blood sample for compatibility testing was drawn from the 'wrong' patient, the intended patient either did not carry a wristband or the transfusion codes did not match at all. Pretransfusion compatibility tests were performed on 2189 patient samples using this procedure. It was well accepted by both ward and blood bank staff. Two potential mismatched transfusions were avoided. These two clerical errors would not have been detected because neither patient had previous ABO grouping results.

Blood Banks↗
PubMed1999

Identification of a human anti-CD55 single-chain Fv by subtractive panning of a phage library using tumor and nontumor cell lines.

A large naive human single-chain (sc) Fv phage library was used to search for tumor-associated antigens by panning with a lung adenocarcinoma cell line, 1264, and counter-selecting with a nontumor bronchial epithelial cell line, BEAS-2B. After three rounds of subtractive panning, 239 of 673 clones analyzed bound selectively to 1264 tumor cells in a phage ELISA. Diversity analysis of these tumor-selective clones by BstNI fingerprinting and nucleotide sequencing revealed 14 distinct scFv fragments. Four clones bound selectively to 1264 over BEAS-2B cells when analyzed by a more discriminating flow cytometric assay using scFv. Moreover, these clones showed only limited cross-reactivity to several primary human cell lines. One clone, LU30, also cross-reacted strongly with the lung adenocarcinoma line, A549. The LU30 antigen was identified as decay-accelerating factor (CD55) by expression cloning from a 1264 cDNA library. The mean number of decay-accelerating factor molecules on the surface of 1264 and BEAS cells used for panning and counter-selection was estimated as 75,000 +/- 5,000 and 13,000 +/- 10,000, respectively. Thus, phage library panning combined with expression cloning permits identification of antibodies and their cognate antigens for proteins that are differentially expressed on the surface of distinct cell populations.

Antigens, Tumor-Associated, Carbohydrate↗