PubMed Health⌕ Search

Biomedical subjects

P K Ng

Publications and source records attributed to P K Ng.

At least 19 recordsLinked to original sources
PubMed2004

Feasibility of implementing a universal neonatal hearing screening programme using distortion product otoacoustic emission detection at a university hospital in Hong Kong.

OBJECTIVE: To assess the feasibility of implementing a universal neonatal hearing screening programme using distortion product otoacoustic emission detection at a major teaching hospital in Hong Kong. DESIGN: Descriptive study and questionnaire. SETTING. Teaching hospital, Hong Kong. METHODS: A total of 1064 infants, together with their mothers, were successfully recruited for the study. The participation rate was 99.3%. A three-stage hearing screening protocol using distortion product otoacoustic emission detection was adopted. Each of the participating infants was screened on three separate occasions (day 1-4, day 5-14, and day 21-30 after birth), irrespective of the test results. A questionnaire was administered to 364 randomly selected mothers to determine whether as consumers of the hearing screening service, mothers would find screening desirable. RESULTS: Results of the screening demonstrated an incidence of permanent bilateral hearing loss (>or=40 dB in the better ear) of 0.28%. The results also showed that 3.5% of the screened infants were referred for subsequent diagnostic audiological assessment, including those suspected with unilateral as well as bilateral hearing loss. Data obtained were comparable to other reported results obtained using multi-stage screening protocols. Taking both the false positive rate and the default rate into consideration, the most appropriate time for screening in this hospital setting appeared to be around day 5 to 14 when infants returned to the hospital's day centre as out-patients for routine medical follow-up. Since this day centre service is not generally provided by all maternity hospitals in Hong Kong, an alternative time for screening would be around day 21 to 30 when infants could return as out-patients solely for the hearing test. The results of the questionnaire suggested that most mothers thought a neonatal hearing screening would be desirable (91.35%). The majority (81.70%) indicated a preference for screening either within a few days of birth at the maternity ward prior to discharge from the hospital, or between 5 and 30 days when returning to the hospital as an out-patient. CONCLUSION: It was concluded that a universal neonatal hearing screening programme could be readily implemented in a maternity hospital setting in Hong Kong.

Clinical Protocols↗
PubMed2001

The role of ruthenium and rhenium diimine complexes in conjugated polymers that exhibit interesting opto-electronic properties.

This paper reports the synthesis and opto-electronic properties of different conjugated polymers that contain the diimine complexes of ruthenium or rhenium. Conjugated poly(phenylene vinylene)s that contain aromatic 1,3,4-oxadiazole and 2,2'-bipyridine units on the main chain were synthesized by the palladium catalyzed olefinic coupling reaction. Other types of polymers based on 1,10-phenanthroline bis(2,2-bipyridyl) ruthenium(II) or chlorotricarbonyl rhenium(I) complexes were also synthesized by the same reaction. In general, these polymers exhibit two absorption bands due to the pi - pi transition of the conjugated main chain and the d-pi* metal-to-ligand charge-transfer transition of the metal complex. As a result, the photosensitivity of the polymers beyond 500 nm was enhanced. Charge-carrier mobility measurements showed that the presence of metal complexes could facilitate the charge-transport process, and the enhancement in carrier mobility was dependent on the metal content in the polymer. In addition, we have also demonstrated that the ruthenium complex could act as both photosensitizer and light emitter. Photovoltaic cells were constructed, and they were subjected to irradiation with a xenon arc lamp. Under illumination, the short circuit current and the open circuit voltage were measured to be 0.05 mAcm(-2) and 0.35 V, respectively. The polymers were fabricated into single-layer emitting devices, and light emission was observed when the device was subjected to forward bias. The maximum luminance was determined to be 300 cdm(-2), and the external quantum efficiency was approximately 0.05 to 0.2%. Although the efficiency was relatively low when compared with other devices based on organic materials, we have demonstrated the first examples of using transition metal complexes for both photovoltaic and light-emitting applications.

Journal Article↗
PubMed2001

Psychosocial adjustment of people with epilepsy in Hong Kong.

PURPOSE: In light of the issues associated with the psychosocial adjustment of people with epilepsy that have been widely reported, this study examined these issues within a Chinese cultural context. METHODS: Fifty patients with epilepsy completed The Washington Psychosocial Inventory, the Coping Inventory for Stressful Situations, and a questionnaire that assessed their psychosocial difficulties and coping styles. Multiple regression procedure was used to examine the strength of various medical and social factors in predicting the psychosocial adjustment problems of these participants. RESULTS: Social factors, such as self-perception and coping strategies, were more powerful predictors of psychosocial adjustment in people with epilepsy than the medical factors associated with epilepsy. CONCLUSIONS: These findings showed that psychosocial maladjustment is a significant issue for people with epilepsy in Hong Kong. The emerging importance of social factors as predictors of psychosocial adjustment in epilepsy, as compared with medical factors, highlights the need for developing tailored counseling therapy and social support groups for people with epilepsy.

Adaptation, Psychological↗
PubMed2001

Epilepsy in Chinese culture.

This article reviewed the meaning and development of epilepsy in Chinese culture. The theories of Yin and Yang and the five elements, fundamentals of traditional Chinese medicine, were introduced, which form the context of understanding of the etiology, classification, and treatment of epilepsy in traditional Chinese medicine.

Animals↗
PubMed1999

Utilization of highly deoxynivalenol-contaminated wheat via extrusion processing.

Deoxynivalenol (DON) is a toxic natural metabolite produced by Fusarium graminearum. In this study we investigated the effects of sodium bisulfite and extrusion cooking under high temperature and pressure on DON levels in wheat grain and mill fractions. Samples of highly naturally DON-contaminated soft winter wheat were soaked for 1 h in water or aqueous sodium bisulfite (SB) solutions (0.5, 1.5, 2.5, or 5% SO2 equivalent) and extruded. The soaking treatment with SB solution (5% SO2 equivalent) lowered DON from 7.3 microg/g to 0.8 microg/g without extrusion and to 0.3 microg/g with an extrusion process. When the contaminated kernels were tempered with water or SB solutions (5 or 10% SO2 equivalent) and milled, the flour samples, as expected, showed lower levels of DON (from 7.3 to 3.1 microg/g). Extrusion of milled flour and whole meal samples, both obtained from SB-tempered wheat, did not change DON levels significantly under the studied extrusion conditions as compared to the nonextruded milled flour and whole meal samples. However, the extrusion process can be utilized to remove moisture and/or odor of chemicals used in the soaking solutions and to produce potentially useful extruded products.

Food Contamination↗
PubMed1997

Peripherally inserted central catheters in general medicine.

OBJECTIVE: To report the success rate and complications associated with peripherally inserted central venous catheters (PICCs) and to compare costs between PICCs and centrally inserted central catheters. MATERIAL AND METHODS: We undertook a cohort study of the first 1,000 patients referred to the PICC service of a large tertiary-care, university-affiliated, community hospital. The data were analyzed for insertion success rate, insertion mode, complication rate, successful completion, insertion costs, and applicability of PICCs in "high-risk" groups (transplant, human immunodeficiency virus-infected, intensive-care unit, and pediatric populations). RESULTS: Of 1,000 consecutive PICC attempts, 963 (96.3%) were successful. Cutdown procedures were necessary in 141 insertions (14.6%). Complications of PICC placement occurred in 170 cases (17.7%). Among the major complications were a need for multiple attempts at insertion in 92 cases, malpositioning in 56, mechanical phlebitis in 37, clotting in 37, and bleeding in 5. The rate for completion of therapy was 68.9%. Frequent reasons for early termination were dislodgment (in 85 cases) and infection (in 72-37 confirmed and 35 potential cases). The rate of confirmed infection was 11 per 10,000 catheter days. The costs of PICC insertion were less than those associated with centrally inserted central catheters. CONCLUSIONS: PICCs can satisfy long-term vascular needs and are safe in many patient populations. The infection rate did not depend on insertion mode, lumen number, or patient's immune status. Use of total parenteral nutrition was the most important risk factor in all patient subsets. Cost and safety considerations strongly favor PICCs as alternatives to other vascular access devices.

Catheterization, Central Venous↗
PubMed1993

Localization of toxins in the poisonous mosaic crab, Lophozozymus pictor (Fabricius, 1798) (Brachyura, Xanthidae).

A hot aqueous extraction method was used to extract toxins from different parts of the poisonous coral reef crab, Lophozozymus pictor. Contrary to an earlier report that crab toxins do not show localization, the toxicity of L. pictor was found to be consistently high in the gut and hepatopancreas, whereas the muscle was less toxic and the carapace was mildly or non-toxic. Crabs kept in captivity for 10 days showed reduction in toxicity in all parts studied with almost complete loss of toxicity after 24 days.

Animals↗
PubMed1993

Process-scale purification of immunoglobulin M concentrate.

An IgM concentrate was purified from Cohn fraction III. Efficiency of euglobin precipitation was shown to be controlled by pH and ionic strength. Prekallikrein activator activity in the product was insignificant. Overall yield from the octanoic acid supernate and purity of the concentrate were 66 +/- 8 (n = 16) and 50 +/- 5% (n = 16), respectively. Solvent-detergent treatment to inactivate lipid-enveloped viruses was demonstrated and implemented into the process. Process studies to control residual virucidal agents and C4a generating activity are presented.

Chemical Fractionation↗
PubMed1991

Polyp of the external ear canal arising from the temporomandibular joint: a case report.

A polypoid mass of granulation tissue in the external auditory meatus was found to be arising from the ipsilateral temporomandibular joint (TMJ). The origin of the lesion was suspected clinically and was confirmed by a CT scan study. As the patient showed signs of psoriatic arthritis, it seems likely that this was the underlying pathological process in the joint. A patent foramen of Huschke allowed herniation of synovial tissue from the joint into the external auditory canal.

Diagnosis, Differential↗
PubMed1987

Biological behavior of 67Ga-citrate in New Zealand White rabbits.

The pharmacokinetics, protein binding, excretion and tissue distribution of 67Ga after the administration of 67Ga-citrate to New Zealand White rabbits is described. Data for 67Ga blood levels were best described by an equation with three exponential components exhibiting half lives of 0.25 h, 7.4 h and 19.5 h, with almost all of the activity in a protein bound form. Weekly urinary excretion (approximately 27%), possibly in a metabolized form, and fecal elimination (approximately 20%) were greater than the reported values in man, but there was a similar organ distribution pattern in these animals as in man. The overall biological handling was judged to be similar in both species making the rabbit a suitable model for further 67Ga-citrate studies in vivo.

Animals↗
PubMed1987

Estrogen receptor-binding affinity and cytotoxic activity of three new estrogen-nitrosourea conjugates in human breast cancer cell lines in vitro.

The hypothesis that more selective antitumor activity may be achieved by cytotoxic agents which selectively bind to estrogen receptors (ER) in human cancer cells was tested. We have synthesized three nitrosourea derivatives of estradiol or hexestrol, and compared the ER binding affinity and cytotoxic activity of these compounds against ER-positive and -negative breast cancer cell lines in vitro. Specific binding to ER in the cytosol of MCF-7 human breast cancer cells was demonstrated in these conjugates: 17 alpha-CNU greater than 17 beta-CNU greater than HEX-CNU greater than lomustine (CCNU). The order of cytotoxicity of these derivatives against human breast cancer cells appeared to correlate with their binding affinity to ER. All three estrogen nitrosourea conjugates were more cytotoxic than CCNU, a clinically useful antitumor nitrosourea which does not bind to ER. The contribution of the estrogen moiety to the cytotoxicity of 17 alpha-CNU was demonstrated by the greater activity of the conjugate than that of a combination of estrogen and CCNU. However, cytotoxicity of these compounds against the receptor-positive MCF-7 and receptor-negative Evsa-T human breast cancer cell lines was similar. The latter finding suggested that cytotoxicity of these conjugates may not be mediated through ER. The difference in stability of these nitrosourea conjugates in aqueous buffer may partly explain their differences in cytotoxicity.

Antineoplastic Agents↗
PubMed1986

Preparation of high purity factor VIII concentrates.

An improved process for producing high purity Factor VIII concentrate has been developed. The improvement was based on the combination of three precipitating agents (polyethylene glycol, glycine and sodium chloride) which heretofore have been used alone in a single step or in separate and distinct steps in a multi-step process. The product was pasteurized in solution (60 degrees C, 10 hrs) to reduce possible risks of virus transmission. The purified product has significantly higher specific activity and lower fibrinogen and immunoglobulin levels when compared to other commercial concentrates.

Chemical Precipitation↗
PubMed1986

Hepatitis B virus associated DNA polymerase inactivation in factor IX concentrates.

Inactivation of Hepatitis B virus associated DNA polymerase was studied in factor IX concentrate (coagulation factors II, VII, IX and X) by heat pasteurization (60 degrees C, 10 hr) and by alkylating agents iodoacetic acid and iodoacetamide. DNA polymerase appeared to reach a residual level which occurred in human serum albumin at 60 degrees C, 10 hr under comparable spike level of hepatitis B virus. Of the four coagulation factors, factor IX activity was most susceptible to inactivation procedures with 40-50% recovery across heat pasteurization and approximately 70% recovery across iodoacetic acid treatment. Factor IX specific activities of the treated concentrates were greater than or equal to 70% of the untreated controls with no appreciable change of corresponding NAPTT values. Factor IX concentrates subjected to such inactivation procedures should reduce the potential for hepatitis B virus transmission.

Blood Coagulation Factors↗
PubMed1986

Effect of cis-platinum treatment on 67Ga-citrate localization and elimination in rabbits.

The treatment of rabbits with a typical dosage schedule of the chemotherapeutic drug cis-platinum resulted in an increased whole body retention of 67Ga-citrate due to decreased urinary and fecal excretion. The biodistribution of the tracer was also affected with most tissues showing greater accumulation. These changes are primarily related to drug-induced renal dysfunction, but other factors may also be involved.

Animals↗
PubMed1985

Pasteurization of antihemophilic factor and model virus inactivation studies.

Heating sterilized albumin preparations at 600 degrees C for 10 hours has historically been shown to yield a hepatitis-free, efficacious product. We have evaluated such a pasteurization procedure with AHF preparations. Procoagulant activity and fibrinogen stability were dependent on the amount of sucrose used as a stabilizer. Flash pasteurization at 72 degrees C was evaluated and was found to be detrimental to AHF. Effect of sucrose concentration was shown on the inactivation kinetics of porcine parvovirus. In the absence of other stabilizers, increased sucrose can provide increased thermoresistance to the virus in 2.5% albumin.

Albumins↗
PubMed1985

Measuring endogenous digoxin-like substance and exogenous digoxin in the serum of low-birth-weight infants.

The interference with three serum digoxin assay methods of endogenous digoxin-like substance (EDLS) in the serum of low-birth-weight (LBW) infants was assessed. The serum from 5-mL blood samples obtained from each of 19 LBW infants was divided into four 0.5-mL portions. Each portion was spiked with 10 microL of a distilled water-ethanol solution with or without digoxin to produce final digoxin concentrations of 0 (control), 0.49, 0.98, or 1.96 ng/mL. Each portion in each patient was then analyzed by radioimmunoassay (RIA), fluorescence polarization immunoassay (FPIA), and radial partition immunoassay (RPIA) using the control portions to measure EDLS. Serum digoxin concentrations measured by each assay method were calculated by subtracting the EDLS concentrations in the control portions from the measured digoxin concentrations in the spiked samples. The mean +/- S.D. concentrations of EDLS measured by RIA and FPIA were 0.26 +/- 0.13 ng/mL and 0.33 +/- 0.16 ng/mL, respectively. Of the 19 control samples assayed by RPIA, 18 had EDLS concentrations less than 0.1 ng/mL; one sample reflected an apparent concentration of 0.11 ng/mL. Mean recovered digoxin concentrations by RIA at each spiked digoxin concentration were significantly different from those obtained by FPIA and RPIA. A low but significant correlation was noted between EDLS concentrations in serum samples assayed by RIA and FPIA. The RPIA method appears to be preferred over the RIA and FPIA methods used in this study for serum digoxin analysis in LBW infants because of acceptable accuracy and minimal interference by EDLS.

Blood Proteins↗
PubMed1985

Multiple-dose kinetics of digoxin in neonates.

Multiple-dose kinetics of digoxin were studied over a 7-day period in five neonates receiving intravenous digoxin therapy (one initial digitalizing dose followed by single daily doses). Their weights ranged from 1.04 to 2.68 kg (means = 1.61 kg), gestational ages from 28 to 39 weeks (means = 31.8 weeks), and postnatal ages from 2 to 19 days (means = 8.0 days). The 24-hour serum digoxin levels and urinary creatinine and digoxin excretion after the 1st and 7th doses on days 1 and 7 were employed to derive the kinetic parameters. Values of each following parameter (mean +/- SD) were obtained on days 1 and 7, respectively: (1) creatinine clearance (ml/min/1.73 m2) 12 +/- 6, 13 +/- 8; (2) renal digoxin clearance (ml/min/1.73 m2) 13 +/- 8, 15 +/- 10; (3) total body digoxin clearance (ml/min/1.73 m2) 35 +/- 14, 39 +/- 24; (4) volume of distribution (L/kg) 7.2 +/- 1.0, 6.9 +/- 1.1; and (5) half-life (hours) 48 +/- 19, 49 +/- 27. No consistent changes of the above kinetic parameters from days 1 to 7 were observed in these five neonates (P greater than 0.05, paired student's t-test).

Birth Weight↗