Biomedical subjects

KC Lam

Publications and source records attributed to KC Lam.

5 recordsLinked to original sources

PubMed2000

First friedel-crafts diacylation of a phenanthrene as the basis for an efficient synthesis of nonracemic

Reported are the first examples of Friedel-Crafts reactions used to prepare 3,6-diacylphenanthrenes. 9,10-Dimethoxyphenanthrene gives its 3,6-diacetyl derivative in good yield and in large amounts. The ketone's triisopropylsilyl enol ether when combined with 1, 4-benzoquinone forms a [7]helicenebisquinone. This bisquinone's reduction product, a bishydroquinone, when combined with methanolic HCl gives the [7]helicene whose peripheral side chains are all methoxyls but whose interior hydroxyls remain. The diastereomeric (1S)-(-)-camphanates can be separated by crystallization. Their structures, analyzed by X-ray diffraction, demonstrate that the camphanates' lactone functions point away from the ring system when the helicene has the (P) configuration and toward it when the helicene has the (M) configuration. This is because the camphanates' O=C-C-O dihedral angles are, as expected, close to 0 degrees in the former and close to 180 degrees in the latter. Other derivatives of 3,6-diacetylphenanthrene and of [7]helicenebisquinone are prepared, and the crystal structure of one of the latter is analyzed.

Journal Article↗

PubMed2000

Why (1S)-Camphanates Are Excellent Resolving Agents for Helicen-1-ols and Why They Can Be Used to Analyze Absolute Configurations.

The questions considered in this paper are why, as agents for resolving helicenols, camphanate esters are particularly effective, and why, in all 19 examples studied, when the (1S)-camphanates of (P)- and (M)-helicen-1-ols are chromatographed on silica gel, the former has the lower R(f)(). Models are proposed for the favored conformations of the esters, and to support the models, evidence is provided from five X-ray diffraction analyses and four ROESY analyses supplemented by molecular mechanics calculations. The essential discovery is that, presumably to avoid a steric interaction between a methyl on the camphanate's bridge and the helicene skeleton, the O=CCO conformation is anti-periplanar in (M)-helicenol camphanates and syn-periplanar in (P)-helicenol camphanates. In the former, the lactone carbonyl points toward the helicene ring system, and in the latter, it points away.

Journal Article↗

PubMed2000

Two phases of

The solvent-bridged caesium phosphide [CsPH(eta6-2,4,6-(t)Bu3C6H2)]2(eta3-toluene)0.5x, catena-[(micro-eta3-toluene)-bis[caesium(2,4,6-tri-tert-butylphenylphosphide)]], undergoes a reversible solid-state, order-disorder phase transition characterized by the doubling of the unit-cell volume at low temperature achieved by doubling one unit-cell vector. The unit-cell parameters at 293 (2) K (form A) are: a = 11.147 (4), b = 14.615 (4), c = 14.806 (5) A, alpha = 70.57 (3), beta = 71.85 (3), gamma = 72.93 (2)degrees, V= 2112.5 (12) A3, Z = 2, rho(calc) = 1.362 g cm(-3), R1 = 0.0513 for 5462 reflections, wR2 = 0.0947 for all data. The unit-cell parameters at 173 (2) K (form B) are: a = 14.6241 (3), b = 14.7393 (3), c = 22.0720 (4) A, alpha = 72.2117 (7), beta = 73.3659 (8), gamma = 70.2953 (7)degrees, V = 4174.8 (2) A3, Z = 4, rho(calc) = 1.379 g cm(-3), R1 = 0.0405 for 14,010 reflections, wR2 = 0.1326 for all data. With a minor change, the key structural features discussed previously for form A [Rabe et aL (1998). Inorg. Chem. 37, 4235-4245] remain unchanged. The eta3-toluene ligand is observed to be disordered at 293 (2) K and ordered at 173 (2) K, with the order-disorder phase transition occurring at approximately 278 (2) K.

Journal Article↗

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.

Journal Article↗

PubMed1999

Hepatic resection for primary liver cancer at a private community hospital: retrospective study of 61 patients.

OBJECTIVE: To review the outcome after surgical resection for primary liver cancer. DESIGN: Retrospective study. SETTING: Private community hospital, Hong Kong. PATIENTS: Sixty-one consecutive patients who underwent liver resection for primary cancer from 1992 through 1997. MAIN OUTCOME MEASURES: Clinicopathological features, type of resection, duration of hospital stay, and actuarial overall and disease-free 5-year survival rates. RESULTS: Cirrhosis was present in 46 (75%) of the patients, and 42 (69%) were positive for hepatitis B surface antigen. The median tumour diameter was 8 cm (range, 1-16 cm). Liver resections consisted of hemihepatectomy (n=37), trisegmentectomy (n=4), segmentectomy (n=11), and wedge resection (n=9). Postoperative death and major morbidity occurred in 0% and 36% of patients, respectively; ascites was the most common complication. The median hospital stay was 11 days. The actuarial overall and disease-free 5-year survival rates were 36.0% and 22.8%, respectively. These results are similar to or better than those recently reported from local or overseas centres. Multivariate analysis showed that the Child-Pugh class significantly influenced the development of complications and the length of hospital stay, whereas a well-circumscribed tumour margin, the tumour-node-metastasis stage of the tumour, and the Child-Pugh class were independent predictors of survival. CONCLUSION: Surgical resection for primary liver cancer can be performed with acceptable safety and efficacy in a suitably staffed and equipped private community hospital.

Journal Article↗