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Biomedical subjects

A Chan

Publications and source records attributed to A Chan.

At least 145 records · Page 8Linked to original sources
PubMed1996

Detection of chimerism and early engraftment after allogeneic peripheral blood stem cell or bone marrow transplantation by short tandem repeats.

Chimerism can be monitored after HLA-matched allogeneic bone marrow transplantation (BMT) or allogeneic peripheral blood stem cell transplantation (PBSCT) by detecting polymorphisms in short tandem repeats (STR). The purpose of our study was to document early complete chimerism in BMT and PBSCT recipients using STR, and to determine whether the initial WBC recovery correlated with the days required to attain complete chimerism. A total of 5 patients (2 PBSCT and 3 BMT) were followed by STR after transplantation. Peripheral blood obtained prior to transplantation was used to determine the 2 most informative STR probes for each donor/recipient pair. STR were amplified by polymerase chain reaction (PCR) with 8 commercial probes, and PCR products were visualized with silver staining. Peripheral blood was evaluated daily post-transplantation for WBC counts and to identify the presence of mixed or full chimerism by STR. The sensitivity of the STR technique varied from 0.05 to 1%, depending on the probe. Full chimerism was documented between day 9 and 14 in PBSCT recipients and on day 14 and 16 in BMT recipients. The initial rise in WBC occurred within 3 days of the onset of full chimerism, indicating that full chimerism is a more sensitive indicator of early engraftment. Periodic recipient monitoring using STR after complete chimerism identifies those patients who revert to mixed chimeras. The STR method may be useful in future studies to determine the significance of early engraftment and the clinical implications of sustained complete chimerism or mixed chimerism.

Adult↗
PubMed1996

Cholesterol and phospholipid levels of washed and percoll gradient centrifuged mouse sperm: presence of lipids possessing inhibitory effects on sperm motility.

Levels of DNA, cholesterol, and phospholipids of mouse caudal epididymal and vas deferens sperm that were processed through simple washing and Percoll gradient centrifugation were measured. The DNA and cholesterol contents of washed sperm and Percoll gradient centrifuged (PGC) sperm (DNA = 3.6 +/- 0.3 pg/sperm and 3.4 +/- 0.3 pg/sperm, respectively; cholesterol = 0.219 +/- 0.057 nmole/microgram DNA and 0.224 +/- 0.030 nmole/microgram DNA, respectively, for washed and PGC sperm) were not significantly different from each other; however, the phospholipid level of PGC sperm was only one half of that of washed sperm (0.315 +/- 0.071 nmole/microgram DNA versus 0.720 +/- 0.075 nmole/microgram DNA, respectively). The presence of 0.3% bovine serum albumin (BSA) in the culture medium used in sperm washing did not change the cholesterol and phospholipid contents of washed sperm. Similarly, the cholesterol and phospholipid levels of washed sperm and PGC sperm that were further incubated in BSA-containing medium for 30 min remained the same. Interestingly, substantial amounts of lipids, as determined by the cholesterol and phospholipid levels, were released into the supernatants of the sperm washes, and sperm needed to be washed at least twice to ensure their stable levels of cholesterol and phospholipids. The lipid mixture in the first sperm wash supernatant was shown to have inhibitory effects on PGC sperm motility.

Animals↗
PubMed1996

EGF stimulates lamellipod extension in metastatic mammary adenocarcinoma cells by an actin-dependent mechanism.

Changes in lamellipod extension and chemotaxis in response to EGF were analysed for MTLn3 cells (a metastatic cell line derived from the 13762NF rat mammary adenocarcinoma). Addition of EGF produced a cessation of ruffling followed by extension of hyaline lamellipods containing increased amounts of F-actin at the growing edge. A non-metastatic cell line (MTC) derived from the same tumor did not show such responses. Lamellipod extension was maximal within 5 min, followed by retraction and resumption of ruffling. Maximal area increases due to lamellipod extension occurred at about 5 nM EGF. Chemotactic and chemokinetic responses, measured using a microchemotaxis chamber, were also greatest at 5 nM. Cytochalasin D inhibited EGF-stimulated responses including lamellipod extension, increases in F-actin in lamellipods, and chemotaxis. Nocodazole affected chemotaxis at higher concentrations but not EGF-induced lamellipod extension. We conclude that polymerization of F-actin at the leading edges of lamellipods is necessary for extension of lamellipods and chemotaxis of MTLn3 cells in response to EGF. The motility and chemotaxis responses of this metastatic cell line have strong similarities to those seen in well-characterized chemotactic cells such as Dictyostelium and neutrophils.

Actins↗
PubMed1996

Outcome studies for burn patients in Hong Kong: patients' satisfaction.

With the recent advances in burns treatment, many more survive the burn to experience pain, scarring, physical deformity, loss of function and psychological trauma. Pressure therapy prescribed by occupational therapists for more than 20 years in Hong Kong has proved its effectiveness in treating the visible scars. However, the inconvenience and impaired appearance that is brought about by these garments during the long phase of therapy bears some weight in worsening patients' social acceptance and happiness in life, also their families especially in children. The objects of the studies were to measure the subjective rating of the effectiveness of pressure therapy through patients' satisfaction towards treatment effectiveness and its effect on daily life. Seventy cases with burn injuries over 1 year previously were selected randomly among the centres for the survey. The scale used was ordinal from 1 to 6. Eleven items concerning treatment effectiveness, life at home, work and leisure aspects were questioned. Results were analysed into two streams-satisfaction towards pressure therapy and change of life satisfaction pre- and post-injury. Non-parametric tests were used for data analysis. Through the Wilcoxon Sign Rank Test and Cluster analysis, major determinants were identified. These factors also showed significant correlation with this demographic data. The conclusions helped to evaluate and improve the existing service in both the garment properties and our scope of therapy for these patients, especially in work rehabilitation and finally (sexual) counselling which should be addressed by a team with interdepartmental support.

Activities of Daily Living↗
PubMed1996

Cost-benefit and cost-effectiveness analyses of behavioral marital therapy as an addition to outpatient alcoholism treatment.

Thirty-six newly abstinent married male alcoholics, who had recently begun outpatient individual alcoholism counseling, were randomly assigned to a no-marital-therapy control group or to 10 weekly sessions of a behavioral marital therapy (BMT) or an interactional couples group. The cost-benefit analysis of BMT plus individual alcoholism counseling showed (a) decreases in health care and legal costs in the 2 years after as compared to the year before treatment, (b) a positive cost offset, and (c) a benefit-to-cost ratio greater than 1 indicating that health and legal system cost savings (i.e., benefits) exceeded the cost of delivering the BMT treatment. None of the positive cost-benefit results observed for BMT were true for participants given interactional couples therapy plus individual alcoholism counseling for which posttreatment utilization costs increased. Thus, adding BMT to individual alcoholism counseling produced a positive cost benefit, whereas the addition of interactional couples therapy did not. Individual counseling both alone and with BMT added showed substantial and significant cost savings from reduced utilization that substantially and significantly exceeded the cost of delivering the treatment; and the two treatments did not differ significantly on these cost savings and cost offsets. Individual counseling alone did have a significantly more positive benefit-to-cost ratio than BMT plus individual counseling due to the lower cost of delivering the individual counseling which was about half the cost of delivering BMT plus individual counseling. Cost-effectiveness analyses indicated that BMT plus individual counseling was less cost effective than individual counseling alone and modestly more cost effective than interactional therapy in producing abstinence from drinking. When marital adjustment outcomes were considered, the three treatments were equally cost effective except during the active treatment phase when BMT was more cost effective than interactional couples therapy. Study limitations are discussed.

Adult↗
PubMed1996

Isoelectric focusing of alphafetoprotein in patients with hepatocellular carcinoma--frequency of specific banding patterns at non-diagnostic serum levels.

Serum levels of alphafetoprotein are raised in 60-80% of patients with hepatocellular carcinoma. Although widely used as a serum marker, frequent false-positive results in patients with benign liver disease, result in poor specificity. This occurs particularly when levels of alphafetoprotein fall between 50-500 ng ml-1, the so-called 'grey area'. Recent reports suggest that isoelectric focusing of alphafetoprotein demonstrates certain bands that are more specific for hepatocellular carcinoma. Our aim was to determine whether the apparent specificity of this new approach is gained at the expense of decreased sensitivity. Sera from 110 patients with a 'non-diagnostic' serum alphafetoprotein level (50-500 ng ml-1) were examined by isoelectric focusing and quantified by densitometric scanning. Ten patients with chronic liver disease and a raised serum alphafetoprotein level (50-500 ng ml-1), but with no evidence of hepatocellular carcinoma, were also studied. Isoelectric focusing revealed characteristic hepatocellular carcinoma bands (bands +II and +III) in 96% patients overall, and 100% of those with levels of total alphafetoprotein greater than 100 ng ml-1. No such bands were seen among ten subjects with cirrhosis but without hepatocellular carcinoma. Bands that are characteristic of hepatocellular carcinoma (bands +II or +III) are seen in the great majority of hepatocellular carcinoma patients; their absence makes a diagnosis of hepatocellular carcinoma extremely unlikely.

Carcinoma, Hepatocellular↗
PubMed1996

The effects of a self-educating blood component request form and enforcements of transfusion guidelines on FFP and platelet usage. Queen Mary Hospital, Hong Kong. British Committee for Standards in Hematology (BCSH).

Despite establishment of transfusion guidelines and feedback intervention, FFP and platelet transfusion were still inappropriate in many clinical situations at our hospital. Many physicians never read or referred to the guidelines when they were ordering FFP and platelet transfusion. A new blood component request form with the guidelines printed on it was designed to facilitate physician education and enforcement of these transfusion guidelines. The form was well accepted by junior house staff and inappropriate transfusion was significantly reduced.

Attitude of Health Personnel↗
PubMed1996

Remifentanil reduces auditory and somatosensory evoked responses during isoflurane anaesthesia in a dose-dependent manner.

We studied 60 patients during stable isoflurane anaesthesia (0.4 MAC) after premedication with temazepam. Patients were allocated randomly to one of three dose regimens of remifentanil: 1 microgram kg-1 i.v. over 1 min and an infusion of 0.2 microgram kg-1 min-1 (low dose); 2.5 micrograms kg-1 and 0.5 microgram kg-1 min-1 (medium dose); and 5 micrograms kg-1 and 1 microgram kg-1 min-1 (high dose). The auditory (AER) and median nerve somatosensory (SER) responses were elicited throughout, and recorded before and after tracheal intubation, and surgical incision, together with systolic and diastolic arterial pressure and heart rate. Venous blood concentrations of remifentanil were measured at the above times. After administration of remifentanil, Pa and Nb amplitudes of the AER increased at the low dose, remained constant at the medium dose and decreased at the high dose. This dose-related effect was linear and significant (P = 0.012, P = 0.05). Pa amplitude correlated inversely with remifentanil blood concentrations before and after intubation and incision (P = 0.002, P < 0.001, P < 0.001 and P < 0.001). In the SER, P15-N20 amplitudes decreased after administration of remifentanil (P < 0.001), whereas P25-N35 and N35-P45 amplitudes increased at all dose concentrations (P < 0.001 and P < 0.001). After intubation, P15-N20 and N35-P45 amplitudes increased at the low dose, did not change at the medium dose and decreased at the high dose (P = 0.001, P = 0.027). After remifentanil, systolic and diastolic arterial pressure and heart rate decreased in a linearly dose-related manner (P = 0.033, P < 0.001, P < 0.001). At all doses the three variables increased after intubation (P = 0.001, P < 0.001, P < 0.01), and systolic and diastolic arterial pressure increased after incision (P = 0.027, P = 0.039).

Adjuvants, Anesthesia↗
PubMed1996

Spontaneous movement after injection of propofol.

Spontaneous movement following injection of propofol at induction was studied in 303 patients. Two hundred patients were Caucasians and 103 were Asians. In a pilot study carried out prior to the main study, 26% of the Asians moved at induction as compared with 6% of the Caucasians. The patients were studied in relation to a number of variables; age, sex, weight, height, race, smoker/non smoker, vegetarian/non vegetarian, alcohol consumption, premedication, use of fentanyl at induction and dose of propofol. When race was included as the sole variable there was a marginal but not significant difference between the two groups in terms of movement (p = 0.06). However, when the other recorded variables were taken into account, race was not included as a predictor of whether or not the patient moved. The best model for predicting whether the patients moved or not combines the variables weight and dose of propofol. Patients were more likely to move if they were lighter and the dose of propofol used at induction was higher.

Adult↗
PubMed1996

Analgesia for day surgery. Evaluation of the effect of diclofenac given before or after surgery with or without bupivacaine infiltration.

One hundred patients undergoing breast lump excision using a standard anaesthetic technique in the Day Care Unit were randomly divided into five groups. Groups A and B received either saline or diclofenac in a double-blind fashion before and at the end of the procedure, with both groups receiving 10 ml of 0.5% bupivacaine infiltration at the end. Groups C and D also received saline or diclofenac before and after surgery but had no bupivacaine infiltration at the end. Group E did not receive any injections but had bupivacaine infiltration at the end of surgery. In the postoperative period, pain was assessed by a visual analogue scale at 30 min intervals until discharge. All patients were requested to complete a pain relief questionnaire over the 48 h following surgery. There were highly significant differences between those who received bupivacaine and those who did not in the visual analogue scale scores at 30 min (p < 0.001), 60 min (p < 0.001), 120 min postoperatively (p = 0.02) and at discharge (p = 0.03). Pain scores were lower in those who received bupivacaine and they were less likely to request rescue medication, although this did not reach significance (p = 0.07). There were significant differences between the groups who received bupivacaine and diclofenac injection and those who received bupivacaine alone for visual analogue scale scores at 60 min following surgery (p = 0.05) and at 48 h (p = 0.002). Pain relief was better in those patients who received both bupivacaine and diclofenac injection. Although not significant (p = 0.22), fewer patients required rescue medication when diclofenac was given before surgery (10%) rather than after surgery (22.5%). Fewer patients had a fair amount or a great deal of pain in the 48 h following surgery when diclofenac was injected before (7.5%) rather than after surgery (12.5%). The mean number of oral analgesics taken in the 48 h after surgery was also lower in those patients who had the diclofenac before the surgery rather than after.

Adolescent↗
PubMed1996

Early tumour response and treatment toxicity after hyperfractionated radiotherapy in nasopharyngeal carcinoma.

The aim of the present study was to undertake a planned interim analysis of a prospective randomized trial comparing the tumour response and the acute and subacute complications of hyperfractionated radiotherapy and conventional radiotherapy in non-metastatic nasopharyngeal carcinoma (NPC). 100 patients with newly diagnosed non-metastatic NPC were randomized to receive either conventional radiotherapy (Arm I) or hyperfractionated radiotherapy (Arm II). Stratification was done according to the T-Stage (modified Ho's T-Stage classification). The biological effective dose (10 Gy) to the primary and the upper cervical lymphatics were 75.0 and 73.1 for Arm I and 84.4 and 77.2 for Arm II, respectively. Hyperfractionated radiotherapy was associated with significant mucositis which is of higher grade than conventional radiotherapy (p = 0.0001), but the duration of mucositis was similar between the two Arms and all study patients completed radiotherapy on schedule without interruption of radiotherapy. Early survival and tumour recurrence rates were comparable between the Arms. The preliminary results indicate that the hyperfractionated radiotherapy has excellent patient compliance in Chinese patients, with acceptable acute and subacute toxicities and the local and regional complete tumour response rates being comparable with conventional radiotherapy. The significance of the time required after start of radiotherapy to achieve a complete tumour response is discussed.

Carcinoma↗
PubMed1996

Short communication: oesophageal tumour volume measurement using spiral CT.

A CT technique for measuring oesophageal cancer tumour volume in the monitoring of local disease response following radiotherapy or chemotherapy is described. Patients with newly diagnosed oesophageal carcinoma were referred for pre- and post-chemotherapy CT scans. IV Buscopan was given to abolish peristalsis. Patients were scanned in prone position. Effervescent gas granules and Calogen (a negative contrast of fat density) were given. Spiral scanning was performed. The area of tumour on each 1 cm slice was measured. The sum of these areas gave tumour volume in cubic centimetres. The accuracy of the method was tested on patients who had had surgery. The volume of the segment of oesophagus containing tumour was measured by its weight and water displacement. Lumenal distention proximal and distal to the tumour was achieved in all patients. 10 gross surgical specimens were available for comparison with pre-operative CT. The correlation coefficient was 0.95. In conclusion, accurate tumour volume assessment was achieved with our technique.

Esophageal Neoplasms↗
PubMed1996

The impact of a gel system on routine work in a general hospital blood bank.

The gel system has been reported to be more sensitive and specific than the conventional tube indirect antiglobulin test (IAT) for antibody screening. However, a major concern about the gel system is its cost. A cost analysis study was therefore conducted at our hospital. The gel system costs more than the conventional tube IAT per test; however, the total staff and reagent costs per year were about equal, because of staff savings. Workload and cost per patient requiring blood were reduced using the gel system.

Journal Article↗