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Biomedical subjects

K H Chan

Publications and source records attributed to K H Chan.

At least 235 records · Page 13Linked to original sources
PubMed1987

Evaluation of monoclonal antibodies for the detection of exfoliative nasopharyngeal carcinoma cells.

Exfoliative cells were aspirated from 15 patients suspected of having nasopharyngeal carcinoma (NPC) and showing the presence of lesions or other abnormalities in the nasopharynx. They were tested for binding with a 125I monoclonal antibody (MAb) (MA6) which is selectively reactive against human B lymphocytes and a variety of carcinomas. A positive result was obtained from 6/9 patients with, and from 0/5 patients without, histologically confirmed disease. One patient with eskimoma also gave a negative binding result. Cytology was specific but less sensitive, tumour cells being detected in 3 of the patients with confirmed disease. Immunocytology using MA6 was limited, like cytology, by poor recovery of the tumour cells and the results were in complete concordance with cytology. The other MAbs used were raised against carcinoembryonic antigen (CEA) and a carcinoma cell line (Ca2), respectively. The latter was not reactive against the NPC tumour cells while the CEA antibody was not sufficiently selective to be useful.

Adult↗
PubMed1987

Characterization of a murine monoclonal-antibody-defined B-lymphocyte carcinoma cross-reacting antigen (BLCa) from nasopharyngeal carcinoma tissues.

Biopsies were obtained from 12 patients suspected of having nasopharyngeal carcinoma (NPC). A portion of the tissue was submitted for histopathology and another for Western blotting using a murine monoclonal antibody (MAb), MA6. Touch smears of the tissues were also prepared immediately prior to extraction and Western blotting for immunoenzymic staining. The results showed that a B-lymphocyte carcinoma cross-reacting antigen (BLCa), or an antigen similar to it, was the major antigen in the tumor tissue recognized by MA6. The antigen was detected in tissues from 8 patients, of whom 7 had confirmed NPC and one had eskimoma, but not in tissue from the remaining 4 patients who did not have histologically confirmed malignancy. Immunocytology showed that tumour cells were present in the touch smears from all but one of the tumour patients but not in the other patients, and that the tumour cells comprised the large majority of the MA6-reactive cell population. The other MA6-reactive cell types present included certain weakly reactive epithelial cells and occasional lymphoid cells, presumably B lymphocytes. However, these cell types were similarly distributed between the tissues obtained from patients with or without malignant diseases. It was concluded, therefore, that the tumour cells in these tissues are the principal source of BLCa and, as such, the antigen may constitute an objective and reliable marker of NPC.

Animals↗
PubMed1987

Characterization of a human B-lymphocyte carcinoma cross-reacting antigen (BLCa) in B lymphocytes identified by two murine monoclonal antibodies.

The murine monoclonal antibody (MAb) MA6 is selectively reactive against a large variety of human B lymphocytes including those in early stages of B-cell differentiation such as committed progenitors of B lymphocytes, pre-B lymphocytes, Burkitt lymphoma cells, and those at later stages of differentiation such as peripheral blood B lymphocytes and myeloma cells. The major antigen identified by this antibody on such B lymphocytes (BLCa) is a 55-kDa glycoprotein or a group of similar glycoproteins, with the MA6-reactive determinant localized on the carbohydrate moiety. On isoelectric focusing, this antigen exhibits a degree of charge microheterogeneity, migrating as a diffused band with an average isoelectric point at pH 5.7. BLCa was also identified by another murine MAb, MA5. The antigenic determinant recognized by this antibody is also localized on the carbohydrate moiety of the molecule, but, unlike the MA6-reactive determinant, it is shared by other glycoproteins from different types of cells.

Animals↗
PubMed1987

In-vitro ligament tension pattern in the flexed knee in passive loading.

Tensions generated in selected bands of the four major ligaments of the flexed knee (40-90 degrees) have been measured in vitro when the tibia is subjected to passive anterior translation and axial rotation with and without a compressive preload. The measurements were made in 30 fresh-frozen specimens using the buckle transducer attached to the anteromedial band of the anterior cruciate ligament [ACL (am)], the posterior fibres of the posterior cruciate ligament [PCL (pf)], the superficial fibres of the medial collateral ligament [MCL (sf)], and in the total lateral collateral ligament (LCL). Particular attention was placed on the evaluation of the performance of the transducer specific to such measurements in order to minimize the errors associated with the use of this transducer. The results indicate that, among the measured ligaments, substantial tension (greater than 20 N) is generated only in the ACL (am) in tibial anterior translation up to 5 mm. The tension pattern generated in response to tibial axial rotation, however, is complex and exhibits considerable variation between specimens. In general, both the MCL (sf) and LCL are tensed at all tested flexion angles, with the tension in external rotation being significantly greater than in internal rotation. At 40 degrees of flexion, the ACL (am) bears tension mainly in internal rotation, while at 90 degrees of flexion the PCL (pf) is tensed in both senses of rotation. The response of the LCL shows marked variation among specimens; very small tension (less than 15 N) is generated in internal rotation in 48% of the specimens, and in either sense of rotation in 20% of the specimens. The tension in the ACL (am) in internal rotation is invariably greater in those specimens in which LCL tension is negligible. This correlation between increased ACL (am) function and inadequate LCL restraint appears significant in terms of ACL injury and repair.

Humans↗
PubMed1987

A murine monoclonal antibody specific for the outer core oligosaccharide of Salmonella lipopolysaccharide.

Immunoglobulin G3 murine monoclonal antibody T6 specific for the lipopolysaccharide of Salmonella O serogroups A to E was established. By using R mutants of Salmonella spp., Escherichia coli, and Shigella spp., the major reactive epitope with T6 was tentatively identified as the terminal disaccharide, N-acetylglucosamine 1.2----alpha glucose, of the core oligosaccharide. T6 was reactive with 10 clinical isolates of each of the Salmonella O serogroups A to E but not with 58 isolates of other gram-negative bacteria. Its selective reactivity against Salmonella spp. renders T6 a potentially more useful reagent than the conventional polyvalent serum for the identification of Salmonella spp. It may also serve as a useful molecular tool for the study of the outer core structure of all Salmonella and related species.

Antibodies, Bacterial↗
PubMed1987

Severe thrombocytopenia due to combined cimetidine and phenytoin therapy.

Combined use of cimetidine and phenytoin among 1512 neurosurgical patients has led to severe thrombocytopenia in 4 patients. One died, and 1 became vegetative. We propose that cimetidine and phenytoin act synergistically to depress the megakaryocyte at the bone marrow. Because thrombocytopenia and inadequate hemostasis are hazardous in neurosurgery, we recommend discontinuation of the cimetidine and phenytoin combination.

Adult↗
PubMed1987

Autoinflation of eustachian tube in young children.

Inflation of the middle ear has long been thought to be beneficial in the treatment of otitis media. We describe a new system of autoinflation based on a modified Valsalva technique consisting of an anesthesia mask and a flowmeter which can be used successfully by children. An objective method to record eustachian tube opening during autoinflation using frequency spectrum analysis of the ear canal sounds is also presented. Tubal opening results of this method were compared to the traditional method using preinflation and postinflation tympanometry. Study subjects included 20 adults with normal otologic findings and 35 children with middle-ear effusion; all together 107 ears of children and adults with and without effusion were tested. Using the frequency spectrum analysis, tubal opening was recorded in 75% of adult ears and 56% of children's ears. Also, in both groups, a sound pressure peak with the same characteristic frequency around 2 kHz was associated with tubal openings. The methods described are incorporated into a clinical trial being conducted at the Children's Hospital of Pittsburgh.

Acoustic Impedance Tests↗
PubMed1987

An instrument using variation of resistance to aid in needle tip insertion in epidural block in monkeys.

A new method is proposed to detect the entrance of a needle into the epidural space. Measuring the changes in electric resistance during the insertion of the needle through different tissues in the interspinal space can help anesthesiologists judge whether and when the needle has entered the epidural space. This preliminary, animal study showed that the proposed method performed quite satisfactorily. The electric resistance of the tissues in the interspinal space varied from 1.57 +/- 1.22 k omega to 2.93 +/- 1.14 k omega, and the resistance of the epidural space varied from 9.00 +/- 1.12 k omega to 14.64 +/- 1.25 k omega. The difference was statistically significant (p less than 0.001). This difference in the resistance can be used to verify placement of the tip of the needle in the epidural space and help anesthesiologists administer epidural anesthesia.

Anesthesia, Epidural↗
PubMed1987

Strong association between the major histocompatibility complex and systemic lupus erythematosus in southern Chinese.

The distribution of HLA-A, B, and DR alleles has been studied in 100 Chinese patients with systemic lupus erythematosus and in 100 healthy Chinese controls. Complement components factor B, C4A and C4B were studied in 72 patients and 61 controls. There was no significant difference between patients and controls in the distribution of HLA-A, HLA-B, factor B and C4B alleles, but there was a significant excess of HLA-DR2 and C4A null in the patients. An unusual variant of C4B was found in 6 patients and 1 control. The possible role of haplotypes is considered in interpreting these results and relating them to previous findings in Chinese.

Adolescent↗
PubMed1986

Skull fractures in children: their assessment in relation to developmental skull changes and acute intracranial hematomas.

Retrospective analysis of 12,072 pediatric head injury cases revealed 1,297 skull fractures. Patients with skull fractures were divided into four age groups according to the fusion of skull sutures and other developmental radiological skull changes. Results revealed that the patients with open skull sutures (aged less than 2 years) and with linear skull fractures alone had a negligible chance of developing intracranial hematomas. With the fusion of metopic and mendosal sutures associated with other skull changes (greater than 2 years), the children became progressively more susceptible to developing intracranial hematomas if they had a skull fracture. The risk of developing intracranial hematomas was the highest among those patients (much greater than 11-15 years) whose paranasal sinuses had reached adult size and spheno-occipital synchondrosis had begun to fuse.

Adolescent↗
PubMed1986

Efficacy and safety of recombinant hepatitis B vaccine in infants born to HBsAg-positive mothers.

Infants born to HBsAg-positive women were randomly assigned to receive either the plasma-derived hepatitis B vaccine or the yeast-derived recombinant hepatitis B vaccine within 12 h of birth, simultaneously with HBIg. The second and third doses of both vaccines were given at 1 and 6 months of age respectively. Two hundred and twenty-two infants received two doses, and 80 infants received three doses of either vaccine. Five infants were found to be HBsAg-positive at 6 months of age. Four of these infants had received the plasma vaccine and the remaining infant the recombinant vaccine. Anti-HBs was present in all the HBsAg-negative infants at 6 months of age. The titres of anti-HBs were similar in both groups of infants who had received either the plasma or the recombinant hepatitis B vaccine. No major adverse reactions were reported with either vaccine. The preliminary results from this study suggest that the yeast-derived recombinant hepatitis B vaccine is safe, immunogenic and at least as effective as the plasma-derived hepatitis B vaccine in preventing the HBsAg carrier state in infants born to HBsAg-positive women.

Carrier State↗