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Biomedical subjects

K C Lam

Publications and source records attributed to K C Lam.

At least 19 recordsLinked to original sources
PubMed2002

[Comparison of ISE, ASV and FQ for complexation characterization of river water DOC with copper].

Condition stabilization constants of complexation between naturally occurring organic ligand in river water and copper were measured lgk and compared by using ISE, ASV and FQ methods. The measured lgk results were 2.29-6.47 by ISE, 2.61-6.91 by ASV, and 3.52-4.71 by FQ, respectively. The constants went up with the raise of pH, the decrease of copper content, and the increase of ligand concentration.

Copper↗
PubMed2001

Respiratory suspended particulate (RSP) concentration and its implications to roadside workers: a case study of Hong Kong.

Respiratory Suspended Particulates (RSPs) have attracted increasing interest in recent years because of the potential risk of RSPs to human health. In Hong Kong, a large population of roadside workers is believed to be continuously exposed to high levels of RSPs. In this study, the roadside RSP concentrations at 72 locations in 6 urban districts of different land use types in Hong Kong are examined. Results show that the RSP pollution in Hong Kong's roadside environment is quite serious. The average RSP concentration at 61.11% of sampling sites is over 180 microg m(-3), the highest 24 h RSP mean concentration recommended by the Environmental Protection Department of Hong Kong. Analyses of RSP concentration data with reference to the local environmental conditions indicate that, among various environmental factors, land use, population density and traffic flow are important determinants of the RSP level. Because many roadside workers are exposed to high levels of RSP for prolonged periods, it is necessary to increase the public awareness of the health hazard of roadside workers.

Air Pollutants↗
PubMed2001

Examining maintenance responsibilities.

This paper has examined the important responsibilities of the two organisations involved in the provision of maintenance service for the vital building services in many of our highly serviced buildings. The issues raised could be put to beneficial use in both clients and maintenance providers. All in all, the clients should work closely with their maintenance providers. Engineering services in buildings will not perform satisfactorily and efficiently if both parties do not work together and understand the maintenance tasks based on a business partnering mode. Put forward is the view that the management of the activities involved in the operation and maintenance process is a "shared commitment/involvement" between the client and the maintenance provider. It is obvious that many factors can influence the continued effectiveness of a quality maintenance scheme set up by client and provider. Some of these factors are: Change in key personnel Updates in technology Amendments to engineering practice Implementation of legislative requirements Changes in operation by client or provider Change of use of building Passage of time These factors must be fully reviewed by both parties from time to time, and necessary actions taken. A cooperative team working relationship and improved communication should be fostered by the client and his provider for the best management of services maintenance. This arrangement will contribute to better building services systems with continuous improvement; improved value for clients and higher return for the maintenance provider.

Cooperative Behavior↗
PubMed2000

Synthetic models for the zinc sites in the methionine synthases.

The syntheses and molecular structures of a series of tetrahedral zinc complexes designed to model the active sites in Escherichia coli methionine synthases are reported. [PhTttBu]ZnBr (PhTttBu = phenyltris((tert-butylthio)-methyl)borate) was prepared and characterized crystallographically to provide entry into [S3]ZnX complexes. Metathesis with KSPh yielded the phenylthiolato complex, [PhTttBu]Zn(SPh), which represents a structural mimic of the homocysteine ligated form of the enzyme. Alternatively, [S2N]ZnX (X = Br, CH3, SPh) species were prepared using the new mixed-donor ligands, [Ph(pz)BttBu] (phenyl(pyrazolyl)bis((tert-butylthio)methyl)borate) and [Ph(pztBu)BttBu] (phenyl(3-tert-butylpyrazolyl)bis((tert- butylthio)methyl)borate). Protonolysis of [Ph(pztBu)-BttBu]Zn(CH3) by PhSH in toluene yielded [Ph(pztBu)BttBu]Zn(SPh), a synthetic analogue of the homocysteine ligated form of cobalamin-independent methionine synthase (Met E). The average Zn-S bond distance in [Ph-(pztBu)BttBu]Zn(SPh) of 2.37 A compares well with the EXAFS-derived distance of 2.31 A found in the homocysteine-bound form of Met E.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2000

Formation of a tetranuclear copper (II) cluster assembled by metal-assisted hydrolysis and desulfurization of bis(3,5-dimethylpyrazolyl)methylphosphine sulfide, MeP(S)(3,5-Me2Pz)2.

The reaction of methylphosphine sulfide, MeP(S)(3,5-Me2Pz)2, 1, with anhydrous CuCl2 affords a tetranuclear copper cluster[Cu2Cl2(3,5-Me2Pz)3(MePO3)]2, 2, and a dinuclear compound Cu2Cl4(3,5-Me2Pz)4, 3. This reaction involves a metal-assisted desulfurization along with concomitant hydrolysis of P-N bonds. The X-ray structures of 1-3 have been determined, and the crystal parameters for these are the following. 1: space group = C2/c, a = 15.2552(1) A, b = 8.7364(2) A, c = 21.4490(3) A, beta = 93.349(1) degrees, V = 2853.74(8) A3, and Z = 8. 2: space group = P2(1)/n, a = 12.5964(4) A, b = 15.7773(4) A, c = 13.9781(4) A, beta = 116.6280(10) degrees, V = 2483.32(12) A3, and Z = 2. 3: space group = P2(1)/c, a = 8.7137(8) A, b = 13.5493(14) A, c = 11.8847(12) A, beta = 106.179(2) degrees, V = 1347.6(2) A3, and Z = 2. The structure of 2 shows that it comprises two dinuclear copper cores bridged together by two tripodal methylphosphinate, MePO3, ligands. 2 is weakly antiferromagnetically coupled, as revealed by variable temperature magnetic susceptibility measurements.

Journal Article↗
PubMed2000

Home sweet home? A case study of household dust contamination in Hong Kong.

It is well recognized that many heavy metals have chronic effects on humans and as such, they are potential environmental health hazards, particularly to young children (see, for example, Body P, Inglis G, Dolan P, Mulcahy D. Environmental lead: a review. Crit Rev Environ Control 1991;20:299-310). Considerable attention has been paid to the study of metal pollution in city air, roadside dusts and soils. However, there is a lack of concern of the presence of trace metals in house dust in the populous city of Hong Kong, where it has traditionally been assumed that such pollutants are rapidly dispersed by ocean breezes. This research aims at quantifying the concentrations of heavy metals within the home environment in Hong Kong and their relationships with environmental factors. The results of this study seem to suggest that traffic and the age of the building and neighborhood are more important factors than the types of industry and socioeconomic status in affecting household dust contamination. The metal burdens in Kwung Tong, an old area with heavy traffic, are significantly higher than other districts. When a Kruskal-Wallis one-way analysis of variance was performed on the ranked metal concentrations in different housing districts, the Chi-square values are all significant at a probability level of < 0.001. This might be attributable to the fact that there is no highly contaminating industries (such as metal smelters, battery plants and petrochemicals) in Hong Kong. The dust metals may travel from the roads, through the windows and balconies, into the houses, as those homes that do not have their windows opened often had a lower level of contaminants in their house dust (median Cd= 3.6 microg/g; median Cu = 313.2 microg/g; median Pb = 144.6 microg/g; median Mn = 211.6 microg/g; and median Zn = 1,333.7 microg/g). Moreover, those occupants who sweep their floors or dust their furniture on daily bases, or use vacuum cleaners, had a lower level of metals inside their houses. Another finding of interest is that the color of the wall paint used in the house may be another factor influencing the contamination levels.

Air Pollution, Indoor↗
PubMed2000

Titanium alkoxide complexes: condensed phase and gas phase comparisons.

The complex [Ti(2,4-dimethyl-2,4-pentanediolate)2]2 (1) has been synthesized from [Ti(OiPr)4] by transesterification with a stoichiometric amount of 2,4-dimethyl-2,4-pentanediol. We have characterized complex 1 in the solid state by single-crystal X-ray diffraction and in the gas phase by desorption chemical ionization mass spectrometry (DCI-MS). The structural and mass spectrometric data show complex 1 to be stable as a dimer in both the solid and gas phases. The retention of dimeric nuclearity in the gas phase sets complex 1 apart from other simple titanium alkoxide complexes [Ti(OiPr)4] and [Ti(OMe)4]4 that give rise to respective families of molecular ions in the DCI-MS experiment. The highest mass molecular ions for Ti alkoxide complexes in the gas phase may reveal the highest nuclearity that these complexes achieve in condensed phases. According to this interpretation the complex [Ti(OiPr)4] is principally dimeric in the gas phase and probably also in the pure liquid phase and should be represented by the formula [Ti(OiPr)4]2.

Journal Article↗
PubMed2000

Fish uptake of inorganic and mucus complexes of lead.

Carassius auratus were exposed to lead in synthetic water. Mucus secreted from the fish was measured and characterized for its lead binding capacity. The increase in mucus concentration in the water depended on secretion and degradation rates and the former was speeded up by lead. The complexation between mucus and lead can be described based on a single-site interaction model. Lead speciation in the system with or without mucus was calculated using chemical equilibrium modeling. The dominant species of lead was PbCO(3)(0). Other major species included Pb(OH)(+), Pb(OH)(2)(0), Pb(CO(3))(2)(2-), Pb-mucus, and Pb(2+), among which free lead and lead hydroxo complexes were available to fish uptake.

Animals↗
PubMed2000

Management of building services. Procurement for highly serviced healthcare facilities.

The question of whether design and build is the best procurement system is hard to tell as other procurement alternatives (main-contractor and principal services contractor coupled with project management team, and construct management method plus good building team) can also give satisfactory results. Besides, it is also known that there is no standard solution or best buy amongst procurement systems. Indeed, there is no single method of procurement which can be suitable for every project for all time. It is also accepted that the choice and use of an inappropriate procurement system is not the only reason for inefficient project management, people and experience are far more important than strategy. Coordination of building services has a direct bearing on the success of a hospital project. Services must be fully integrated and coordinated. One thing is clear, as far as building services coordination is concerned, the traditional procurement system is not conducive to effect coordination process, however, the integrated nature of D&B has relieved all the burdens on the client's design team, and, from the face of this procurement path, all coordination problems that the client would normally encounter from the traditional method will no longer exist. Of course, the technical and managerial problems in relation to coordination still exist but they would all be passed to the contractor side. To protect the contractor's interest, all coordination problems would still have to be managed and controlled by D&B contractor and his specialist contractors expeditiously. Indeed, if design is not fully integrated, and construction and services are not completely coordinated, no matter how integrated is the team, D&B method will not work. To sum up, the author's discussions can be summarized as follows: Project success can be enhanced by engendering a team spirit and a high degree of cooperation between project participants. This can be achieved by the use of non-traditional procurement systems. Building services and hospital engineering systems must be properly coordinated at both design and installation stages. Coordination must be seen as both technical and managerial issues. A professional building team can manage the complex issues of services coordination. But it is known that an integrated building team can give better result. D&B is not a panacea, other procurement paths with adequate project management can provide a better alternative than either the traditional or the design and build system.

Contract Services↗
PubMed2000

[Uptake of particulate lead via gills of goldfish].

This paper studied the uptake of Pb absorbed on suspended gibbsite via gills of goldfish (Carassius auratus). Under conditions of the concentration of the particulate Pb varied while that of free Pb maintained at a constant level, the levels of both Pb and Al in the gills increased with increasing exposed Pb concentration. The increasing rate (slope 0.171) of Pb level in the blood with the Pb level in the gills was lower than that (slope 0.343) of soluble Pb exposure experiment. Partial Pb adhered on the gills did not transfer into blood. The ratio of Pb/Al in the gills was 1-2 orders of magnitude higher than that in the water, and on the microtome section of filament, the gibbsite particles adhered on gill mucus were observed, indicating the bioavailability of the particulate Pb uptake by the gills of goldfish. The major mechanism was: when the absorbed Pb on suspended particles was flowed into gill filaments, it was desorbed on the surface of gills, and then, passively diffused or transferred by carriers via gill cells into flood, and after the particles stayed on the surface of gill filaments for a short time, in company with sloughed mucus, they were released from the gills along with waterflow.

Absorption↗
PubMed1999

Lamivudine in the treatment of hepatitis B virus reactivation during cytotoxic chemotherapy.

Hepatitis B virus (HBV) reactivation has been described in cancer patients who received cytotoxic/immunosuppressive therapy and may result in liver damage of varying degrees of severity. There is no known effective treatment. Lamivudine, a nucleoside analogue, has been found to suppress HBV replication and to improve histology in chronic carriers of hepatitis B virus. The outcome of lamivudine therapy (at doses of 100 or 150 mg/day) in eight patients who developed HBV reactivation while receiving cytotoxic chemotherapy is described. Each of the eight patients had >98% suppression of the pretreatment HBV DNA levels. Three of the five patients who were initially HBeAg positive underwent seroconversion. Five patients had normalization of liver function tests and improvement in clinical condition. However, one patient died of hepatic failure due to HBV-related submassive liver necrosis, and two died of widespread metastases (including liver) from the primary malignancies. It is concluded that early commencement, i.e., at the onset of HBV reactivation before severe hepatic decompensation, of lamivudine may be effective in the control of HBV reactivation during chemotherapy. In Hong Kong, where hepatitis B infection is endemic, we propose to screen all cancer patients for hepatitis B surface antigen before immunosuppressive/cytotoxic therapy, and to closely monitor liver function of those who are found to be HBsAg seropositive.

Adult↗
PubMed1998

Multimodality treatment of primary lymphoepithelioma-like carcinoma of the lung.

BACKGROUND: Lymphoepithelioma-like carcinoma (LELC) of the lung occurs at a higher frequency in Asian compared with Western patients. Its association with Epstein-Barr virus varies among different ethnic groups. METHODS: Nine patients with primary LELC of the lung treated at a single institution with a multimodality approach comprised of surgery, chemotherapy, and radiotherapy are reported. Chemotherapy was comprised of cisplatin, 100 mg/m2, on Day 1 and 5-fluorouracil, 1 g/m2, on Days 2, 3, and 4. RESULTS: Five male and 4 female patients were treated over a 3-year period. Eight patients were non-smokers. Three patients had operable disease. Two of these patients received adjuvant radiotherapy or chemotherapy and remained free of recurrence at 18 and 20 months, respectively; 1 patient received no adjuvant treatment, and palliative chemotherapy was given for subsequent recurrent disease. Six patients had inoperable disease and received palliative chemotherapy +/- radiotherapy. Five patients had distant metastatic disease at presentation. Of the 7 patients who were evaluable for response to chemotherapy, 71.4% had a partial response and 28.6% had progressive disease. One patient who was evaluable for response to radiotherapy achieved a partial response. CONCLUSIONS: Primary LELC of the lung has a high rate of systemic metastasis and is highly chemosensitive. A multimodality approach to the management of this disease is recommended.

Adult↗
PubMed1998

Are nursery schools and kindergartens safe for our kids? The Hong Kong study.

Pediatric heavy metal (particularly lead) poisoning is a widespread, yet preventable problem in many parts of the world. Interior floor dust is found to be one of the major pathways of childhood exposure. However, school and health authorities in most countries do not have any stipulations nor guidelines in regulating heavy metal contamination in floor dusts in schools. This study attempts to examine the level of heavy metal contamination in 53 nursery schools and kindergartens in Hong Kong and study its relationship with the environmental factors. The results of this study reveal that the arithmetic mean level of lead in exterior dust is 280.01 mg/kg, with a minimum level of 48.80 mg/kg and a maximum of 2108.31 mg/kg, which is somewhat lower than other studies, such as those reported by Chan et al. (Biomed. Environ. Sci. 1989;2:131-140) and Akhter and Madany (Water Air Soil Pollut. 1993;66:111-119), but those of the manganese (mean = 532.16 mg/kg, range = 102.51-1736.25 mg/kg) and zinc levels (mean = 2694.23 mg/kg, range = 898.33-9899.85 mg/kg) are much higher. Out of the 10 districts examined, Kwun Tong and North Point are found to be the most polluted. They are older districts with polluting industries and heavy traffic. The results of the analysis of variance suggest that the heavy metal particulate may originate from the exterior. Auto-vehicles are a likely source. The toxins are blown inside through the opened windows. Other factors that may affect the content of metal in floor dusts are the time since the school was last painted, the age of the housing complex, the condition of the school and the use of vacuum cleaners.

Child, Preschool↗
PubMed1996

Outmigration of U.S. immigrants.

"A methodology is devised for the empirical analysis of the determinants of outmigration of immigrants in a population. Empirical studies in this area have been hindered by a lack of longitudinal data on the characteristics of the immigrants. This problem is tackled by making use of cross-sectional data at two points in time. It is applied to the study of male immigrants in the United States. It is found that education is positively related to the rate of outmigration for immigrants from Canada, Asia and the pooled sample of immigrants. This finding suggests that the cross-sectional estimates of the growth in earnings of immigrants in the United States are underestimated for these groups of immigrants."

Americas↗
PubMed1983

Clear cell carcinoma of liver. An ultrastructural study.

A light microscopic and ultrastructural study of ten consecutive cases each of the clear cell type and nonclear cell type of hepatocellular carcinoma (HCC) showed important differences between the two groups which may help to explain their different biological behavior. The clear cells contained substantial quantities of glycogen and lipid which partly substitute the usual cytoplasmic constituents. An analogy was made between these tumor cells with clear cytoplasm and the clear cells which occurred in the intermediary stages of hepatocellular carcinogenesis in animals in an attempt to explain the better outcome of clear cell HCC.

Adenocarcinoma↗