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Biomedical subjects

M K Lee

Publications and source records attributed to M K Lee.

At least 19 recordsLinked to original sources
PubMed1992

Location of a Bombyx mori receptor binding region on a Bacillus thuringiensis delta-endotoxin.

Receptor binding studies were performed with 125I-labeled trypsin-activated insecticidal toxins, CryIA(a) and CryIA(c), from Bacillus thuringiensis on brush-border membrane vesicles (BBMV) prepared from Bombyx mori larval midgut. Bioassays were performed by gently force feeding B. mori with diluted toxins. CryIA(a) toxin (LD50; 0.002 micrograms) was 200 times more active against B. mori larvae than CryIA(c) toxin (LD50; 0.421 micrograms) and showed high-affinity saturable binding. The Kd and the binding site concentration for CryIA(a) toxin were 3.5 nM and 7.95 pmol/mg, respectively. CryIA(c) toxin (Kd, 50.35 nM; Bmax, 2.85 pmol/mg) did not demonstrate high-affinity binding to B. mori BBMV. Control experiments with CryIA(a) and CryIA(c) toxins revealed no binding to mouse small intestine BBMV and nonspecific binding to pig kidney BBMV. These data provide evidence that binding to a specific receptor on the membrane of midgut epithelial cells is an important determinant with respect to differences in insecticidal spectrum of insecticidal crystal proteins. To locate a B. mori receptor binding region on the CryIA(a) toxin, homologous and heterologous competition binding studies were performed with a set of mutant proteins which had previously been used to define the B. mori "specificity domain" on this toxin (Ge, A. Z., Shivarova, N. I., and Dean, D. H. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 4037-4041). These mutant proteins have had regions of their genes reciprocally exchanged with the cryIA(c) gene. A B. mori receptor binding region on CryIA(a) toxin includes the amino-terminal portion of the hypervariable region, amino acids 332-450, which is identical to the previously described B. mori specificity determining region. These data provide direct evidence that delta-endotoxins contain a tract of amino acids that comprise a binding region and as a results determines the specificity of a toxin.

Amino Acid Sequence↗
PubMed1992

Intraocular pressure-related pattern of optic disc cupping in adult glaucoma patients.

The pattern of glaucomatous optic disc cupping was investigated in 67 eyes of 67 primary open-angle glaucoma patients with early-to-moderate visual field loss and a wide range of intraocular pressure. We determined the position of the deepest point of the optic disc cup using the Rodenstock Analyzer. This position correlated significantly with intraocular pressure: the deepest point tended to be located below the center of the optic disc at high intraocular pressure and above the center at low intraocular pressure. There was no significant correlation between the position of the deepest cup point along the horizontal axis and intraocular pressure. The position of the deepest point of the cup also correlated significantly with the severity of glaucoma, albeit less strongly than with intraocular pressure: it tended to be in the inferior portion of the disc at an early stage of glaucoma and in the superior portion of the disc at a more advanced stage of glaucoma. Therefore, the inferior portion of the optic nerve head appears to be most yielding to changes of intraocular pressure. These findings are consistent with histologic evidence of the least connective tissue support in the inferoperipheral region of the lamina cribrosa and with greater prevalence of inferior rim loss and corresponding superior visual field defects in early to moderately advanced primary open-angle glaucoma patients.

Aged↗
PubMed1992

Isolation and chromosomal assignment of 100 highly informative human simple sequence repeat polymorphisms.

One hundred highly informative simple sequence repeat (SSR) polymorphisms have been isolated and mapped to specific human chromosomes by somatic cell hybrid analysis. These markers include 97 (CA)n, 2 (AGAT)n, and a single (AACT)n repeat. All the SSRs have heterozygosities greater than 0.50 and can be amplified using identical PCR conditions. At least one SSR was detected on every chromosome, except for chromosomes 22 and Y. The frequency of (CA)n repeats on each chromosome was proportional to the relative chromosomal length, except for chromosome 15, on which a substantial excess of markers was identified.

Base Sequence↗
PubMed1992

Linkage of the epidermolytic hyperkeratosis phenotype and the region of the type II keratin gene cluster on chromosome 12.

Bullous congenital ichthyosiform erythroderma (epidermolytic hyperkeratosis) is a severe, generalized, lifelong disease of the skin. As in epidermolysis bullosa simplex, intraepidermal blisters and clumping of keratin intermediate filaments are characteristic. We report here linkage of the inheritance of this disease to the region of chromosome 12q containing the genes encoding type II keratins. This suggests that keratin gene mutations may underlie this complex hyperproliferative and hyperkeratotic phenotype.

Chromosome Mapping↗
PubMed1992

Neuroleptic malignant syndrome in Malaysia: a university hospital experience.

The neuroleptic malignant syndrome (NMS) is a potentially fatal complication of antipsychotic therapy. A retrospective study of nine patients seen over six years at the University Hospital, Kuala Lumpur (UHKL), is described. The estimated annualised incidence was 1.2 per 1000 in-patients with psychosis. No ethnic difference was detected. Clinical features were similar to experiences elsewhere, with wide variability seen in the severity of illness. The neuroleptic drugs implicated were haloperidol, trifluoperazine, chlorpromazine, fluphenazine and clopenthixol. Treatment consisted of withdrawal of offending drugs and supportive measures. Specific therapy was given to five patients. There was one death. At follow-up no deterioration was detected. A different neuroleptic drug was successfully re-introduced in four patients. In view of the wide usage of major tranquillizers, a high degree of clinical awareness of this serious complication is necessary for early diagnosis to reduce morbidity and mortality.

Adolescent↗
PubMed1992

Closing in on a breast cancer gene on chromosome 17q.

Linkage of early-onset familial breast and ovarian cancer to 11 markers on chromosome 17q12-q21 defines an 8-cM region which is very likely to include the disease gene BRCA 1. The most closely linked marker is D17S579, a highly informative CA repeat polymorphism. D17S579 has no recombinants with inherited breast or ovarian cancer in 79 informative meioses in the seven families with early-onset disease (lod score 9.12 at zero recombination). There is no evidence for linkage heterogeneity in the families with early-onset disease. The proportion of older-onset breast cancer attributable to BRCA 1 is not yet determinable, because both inherited and sporadic cases occur in older-onset families.

Base Sequence↗
PubMed1991

Characterization of posttranslational modifications in neuron-specific class III beta-tubulin by mass spectrometry.

Class III beta-tubulin, isolated from adult bovine brain, is resolved into at least seven charge variants on isoelectric focusing gels. To identify the posttranslational modifications responsible for this heterogeneity, a mixture of brain tubulins was treated with cyanogen bromide and the C-terminal fragments from the class III beta-tubulin isoforms were then isolated by binding them to the monoclonal antibody TuJ1. Combined use of tandem mass spectrometry and both subtractive and automated Edman degradation chemistry on the isolated peptides indicates that many of the isoforms differ by phosphorylation at Ser-444 plus attachment of one to six glutamic acid molecules to the side chain of the first glutamate residue, Glu-438, in the C-terminal sequence Tyr-Glu-Asp-Asp-Glu-Glu-Glu-Ser-glu-Ala-Gln-Gly-Pro-Lys.

Amino Acid Sequence↗
PubMed1991

Analysis of affinity and structural selectivity in the binding of proteins to glycosaminoglycans: development of a sensitive electrophoretic approach.

Members of several families of cell surface and secreted proteins bind glycosaminoglycans (GAGs), the structurally heterogeneous polysaccharides found on proteoglycans. To understand the physiological significance of the interactions of proteins with GAGs, it is critical that relationships between GAG structure and binding be analyzed. It is particularly important that interactions depending on common structural features of GAGs (e.g., size, charge density, and disaccharide repeat unit) be distinguished from those mediated by specific sequences of carbohydrate modification. Gathering the information needed to make such distinctions has so far been difficult, however, partly because structurally homogeneous samples of GAGs are lacking but also because of technical difficulties associated with performing and interpreting assays of protein-GAG binding. We describe an electrophoretic method useful for both measuring affinity and evaluating structural selectivity in protein-GAG binding. Data are presented on the binding of the GAG heparin to the protease inhibitor antithrombin III, the acidic and basic fibroblast growth factors, and the extracellular matrix protein fibronectin. Results obtained with fibronectin are consistent with a model in which high-affinity binding (Kd approximately 34 nM) is mediated through the recognition of specific carbohydrate sequences.

Animals↗
PubMed1991

Age differences in the proliferative response of cultured arterial smooth muscle cells induced by sera of hypothalamically-stimulated rats.

In an earlier report, it was shown that arterial smooth muscle cells (ASMC) cultured from normal rat aorta, proliferated in response to homologous sera from young rats which had received hypothalamic stimulation (HS), in contrast to the effect of sera from non-stimulated age-matched controls (sham-operated). In the present study, this proliferative response was compared in young and old rats. Isolated target cells were subcultured from primary explants of aortic tissue obtained from young, male, Fischer 344 rats, which were electrode-implanted in the hypothalamus but not stimulated. After an initial quiescence period (growth arrest), target cells were exposed to plasma derived serum (PDS) from 4 experimental groups: young stimulated rats; young sham-operated controls; aged stimulated rats and aged sham-operated controls, at PDS concentrations of 2.5% and 5.0% and counted at days 2 and 5. Proliferative responses of ASMC were found to be influenced by concentration of the PDS, age of the donor animal contributing the serum and the presence of HS. The greatest responses were observed in relation to sera derived from aged stimulated rats, especially at the higher concentration, suggesting an interaction of HS with advanced age. These results are discussed in reference to their possible bearing on the pathogenesis of atherosclerosis.

Aging↗
PubMed1991

Growth retardation in senescent arterial smooth muscle cells and its reversal following brain stimulation: implications for atherogenesis.

Advancing age and psychosocial stress are each associated with a rising incidence of atherosclerosis. In this investigation we attempted to answer the question of whether they are independent of each other or not. Since a key feature of atherosclerosis is the proliferation of arterial smooth muscle cells (ASMC), we transplanted aortic tissue from aged rats, half of which had received hypothalamic stimulation, as a model for stress, to growth supporting medium, immediately after stimulation and observed their growth behavior for a period of 4 months. Similar observations were carried out on young animals for comparison. Although there was little difference in outgrowth frequency of explants from young animals between stimulated and non-stimulated subjects, in the case of the older rats, explants from animals which were not stimulated were considerably retarded in their growth, whereas those from subjects which had received HS, grew as well as those of the younger ones. These results show that HS can reverse the growth decline in aortic tissues explanted from senescent rats. They also suggest that age per se is not atherogenic in terms of proliferative behavior of ASMC, whereas when interacted with a stressful condition, this may be the case. Since in the elderly there is a decreased tolerance to stress, the 'atherogenic' effects of age in these individuals may be mediated through the stress response.

Aging↗
PubMed1991

Clinical and immunologic evaluations of reactive dye-exposed workers.

To evaluate type 1 hypersensitivity to reactive dyes, its prevalence, and its relationship to respiratory dysfunction, we studied clinical and immunologic features, including skin prick tests. RAST, and bronchoprovocation tests, of 309 employees working in a reactive-dye industry. Our survey revealed that 78 (25.2%) employees had work-related lower respiratory symptoms associated with or without nasal, skin, or eye symptoms. Among these employees, 38 (48.7%) had nonspecific bronchial reactivity. Thirteen demonstrated immediate (6), dual (6), or late only (1) asthmatic responses after inhalation of four kinds of reactive-dye solutions. Twenty-five employees demonstrated immediate skin responses to black GR dye, and 21 reacted to orange 3R. Fifty-three employees (17%) had specific serum IgE antibody against black GR and orange 3R-human serum albumin conjugate. Specific IgE was detected more frequently in symptomatic employees (30%) and smokers (100%). No association was found between atopy and specific IgE binding. The RAST-inhibition tests of black GR revealed significant inhibitions by black GR-human serum albumin conjugate and minimal inhibitions by unconjugated black GR. Orange 3R RAST-inhibition tests revealed significant inhibitions by conjugated forms of black GR and orange 3R and some inhibitions by two unconjugated dyes, suggesting an immunologic cross-reactivity between these dyes. These findings suggested that reactive dyes could induce immunologic responses, most likely IgE-mediated.

Adult↗
PubMed1991

Identification of major allergens from the house dust mites, Dermatophagoides farinae and Dermatophagoides pteronyssinus, by electroblotting.

The allergens were separated from the extracts of house dust mites by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and identified by autoradiography. Over 30 protein bands of the whole body extract of Dermatophagoides farinae were apparent on 10-20% gradient SDS-PAGE, and 13 bands with MW between 93KD and 12KD bound with specific IgE antibodies in patients' sera sensitive to house dust mites. The major allergenic component of the whole body extract of D. farinae was the protein of MW 14-15KD, which was detected in 95.7% of 47 patients' sera sensitive to house dust mites. The extract of Dermatophagoides pteronyssinus supplied by Bencard Company, England was thought to contain feces enriched material as noted in a few broad protein bands on SDS-PAGE. Seven allergenic components were shown by autoradiography. The protein band of MW 14-15KD was one of the most frequently revealed allergens on autoradiography, which has appeared in 32.5% of 40 patients' sera sensitive to house dust mites. The electrobotting technique used in the present study was fast, convenient and highly useful for both the identification of allergen components and the screening of specific IgE antibody. The individual variations of IgE immune responses to the allergenic components of the two house dust mites were discussed.

Allergens↗
PubMed1991

Complex segregation analysis of primary hepatocellular carcinoma in Chinese families: interaction of inherited susceptibility and hepatitis B viral infection.

Primary hepatocellular carcinoma (PHC) is extremely common in eastern China, where it is both associated with chronic infection with hepatitis B virus (HBV) and often familial. Complex segregation analysis of 490 extended families was undertaken with liability classes defined by age, sex, and HBV infection status. The maximum-likelihood model suggests that a recessive allele with population frequency approximately .25 yields lifetime risk of PHC, in the presence of both HBV infection and genetic susceptibility, of .84 for males and .46 for females. The model further predicts that, in the absence of genetic susceptibility, lifetime risk of PHC is .09 for HBV-infected males and .01 for HBV-infected females and that, regardless of genotype, it is virtually zero for uninfected persons. Complex segregation analysis therefore provides evidence for the interaction of genotype, environmental exposure, sex and age in determining the occurrence of PHC in this population.

Carcinoma, Hepatocellular↗
PubMed1991

Disproportionate body growth in girls with adolescent idiopathic scoliosis. A longitudinal study.

Two thousand, one hundred and eighty-nine southern Chinese women, aged 8-21 years, were studied: 541 with adolescent idiopathic scoliosis (176 treated with posterior spinal fusion and Harrington instrumentation, 150 with brace, and 215 who did not require any treatment), and 1,648 age-matched normal controls from schools and colleges. Scoliotic girls treated at Duchess of Kent Children's Hospital were examined clinically, radiologically, and anthropometrically, including a roentgenogram of the left hand for bone age, at yearly intervals from their first visit to hospital until maturity. Leg:spine and leg:arm ratios were calculated to study the proportionate body growth. The data obtained at first visit and at maturity for each treatment group were compared within treatment groups, and also with normal controls (all age-matched comparisons). The results are summarized as follows: The comparison of leg:spine ratio between fusion, brace, and untreated groups at first visit using uncorrected spinal length showed inconsistent results, but when these ratios were calculated using spinal length corrected for scoliosis, the results were all consistent, showing no significant difference between these groups at first visit. At maturity, leg:spine ratios, using either uncorrected spinal length or corrected spinal length, were highly significantly greater for the fusion group compared to the brace and untreated groups. The leg:spine ratio comparisons of scoliosis groups against normals showed that brace and fusion groups had highly significantly greater ratios at first visit and at maturity, using uncorrected spinal length. Similar comparison using corrected spinal length showed minimum or no difference at first visit, but at maturity, only the fusion group had a significantly greater ratio than normals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Possible linkage of the estrogen receptor gene to breast cancer in a family with late-onset disease.

The estrogen-receptor locus is a candidate gene for inherited susceptibility to human breast cancer, particularly among families with later onset, primarily estrogen-receptor-positive tumors. For one extended family with eight patients with late-onset disease, one estrogen-receptor haplotype was consistently coinherited with breast cancer, yielding a +1.85 lod score for linkage at zero recombination. Simulation of this pedigree assuming independent inheritance of breast cancer and estrogen-receptor genotypes led to a lod score greater than or equal to 1.85 only once in 2,000 replicates. We suggest testing linkage of this gene to breast cancer in other families with late-onset disease.

Adult↗
PubMed1990

Linkage of early-onset familial breast cancer to chromosome 17q21.

Human breast cancer is usually caused by genetic alterations of somatic cells of the breast, but occasionally, susceptibility to the disease is inherited. Mapping the genes responsible for inherited breast cancer may also allow the identification of early lesions that are critical for the development of breast cancer in the general population. Chromosome 17q21 appears to be the locale of a gene for inherited susceptibility to breast cancer in families with early-onset disease. Genetic analysis yields a lod score (logarithm of the likelihood ratio for linkage) of 5.98 for linkage of breast cancer susceptibility to D17S74 in early-onset families and negative lod scores in families with late-onset disease. Likelihood ratios in favor of linkage heterogeneity among families ranged between 2000:1 and greater than 10(6):1 on the basis of multipoint analysis of four loci in the region.

Breast Neoplasms↗
PubMed1990

The expression and posttranslational modification of a neuron-specific beta-tubulin isotype during chick embryogenesis.

Five beta-tubulin isotypes are expressed differentially during chicken brain development. One of these isotypes is encoded by the gene c beta 4 and has been assigned to an isotypic family designated as Class III (beta III). In the nervous system of higher vertebrates, beta III is synthesized exclusively by neurons. A beta III-specific monoclonal antibody was used to determine when during chick embryogenesis c beta 4 is expressed, the cellular localization of beta III, and the number of charge variants (isoforms) into which beta III can be resolved by isoelectric focusing. On Western blots, beta III is first detectable at stages 12-13. Thereafter, the relative abundance of beta III in brain increases steadily, apparently in conjunction with the rate of neural differentiation. The isotype was not detectable in non-neural tissue extracts from older embryos (days 10-14) and hatchlings. Western blots of protein separated by two-dimensional gel electrophoresis (2D-PAGE) reveal that the number of beta III isoforms increases from one to three during neural development. This evidence indicates that beta III is a substrate for developmentally regulated, multiple-site posttranslational modification. Immunocytochemical studies reveal that while c beta 4 expression is restricted predominantly to the nervous system, it is transiently expressed in some embryonic structures. More importantly, in the nervous system, immunoreactive cells were located primarily in the non-proliferative marginal zone of the neural epithelia. Regions containing primarily mitotic neuroblasts were virtually unstained. This localization pattern indicates that c beta 4 expression occurs either during or immediately following terminal mitosis, and suggests that beta III may have a unique role during early neuronal differentiation and neurite outgrowth.

Animals↗