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Biomedical subjects

K Chen

Publications and source records attributed to K Chen.

At least 541 records · Page 30Linked to original sources
PubMed1985

A study of aeroallergens in Nanning, Guangxi, China.

There were 43 families of airborne pollen in Nanning, and the major sensitizing pollens were those of Gramineae, Artemisia (a genus of Compositae), Chenopodiaceae, and Moraceae. It was found that sensitization with pollens of the same genus is similar. This may be helpful in selecting the proper antigen for immunotherapy.

Air Pollution↗
PubMed1984

Aneurysmal bone cyst of the rib.

Aneurysmal bone cysts are uncommon lesions, especially in the ribs. Four patients with aneurysmal bone cysts of the rib are presented and previously reported cases reviewed. A brief discussion of the clinical manifestations, pathology, aetiology, and current treatment of aneurysmal bone cyst is also included.

Adolescent↗
PubMed1984

Proteoglycans in arterial smooth muscle cell cultures: an ultrastructural histochemical analysis.

The extracellular matrix in cultures of arterial smooth muscle cells has been examined by ultrastructural histochemistry using each of the following cationic dyes: ruthenium red, Alcian blue, acridine orange, and safranin O. All dyes exhibited an affinity for a structural component that was either preserved as a granule with ruthenium red or Alcian blue, or as an extended filament or bottlebrush structure with acridine orange or safranin O. Both granules and filaments were removed when the cultures were pretreated with chondroitinase ABC, an enzyme that degrades the glycosaminoglycan moiety of some proteoglycans. These structural components of the extracellular matrix were not observed when cultures were prepared in the absence of the cationic dyes. Labeling experiments (35S-sulfate) revealed that approximately 40% of the total labeled proteoglycans were lost during routine processing for electron microscopy (i.e., fixation through dehydration). Inclusion of any one of the cationic dyes during fixation reduced the losses to less than 1%. The extended filamentous structure preserved by safranin O and acridine orange resembled the structure of purified proteoglycans prepared from the same cultures and spread on cytochrome c monolayer films. These observations suggest that proteoglycans exist as extended bottlebrush structures within the extracellular matrix, and support the interpretation that the granular deposits observed in the ruthenium red and Alcian blue preparations most likely represent individual proteoglycan monomers that have undergone molecular collapse during processing. In addition, the dyes also exhibited an affinity for chords of fine fibrils that contained small granules and/or filaments. Both the fibrillar material and the associated granular and filamentous structures enmeshed in the fibrils resisted digestion with chondroitinase ABC.

Acridine Orange↗
PubMed1982

Biochemical response of lymphoma cells to mitogenic stimulation by prolactin.

A previous study showed that cultured Nb 2 node rat lymphoma cells stopped replicating when transferred to medium supplemented with horse serum instead of fetal calf serum; resumption of growth could be induced by the addition of prolactin or other lactogens. The present study shows that in the absence of prolactin cells accumulated early in the G1 phase from which, on stimulation by the hormone, they proceeded through the cell cycle in a synchronized fashion. Ornithine decarboxylase and S-adenosyl methionine decarboxylase activities were closely related to the proliferative status of the cells. In stationary cultures the enzyme activity was barely detectable; following the addition of prolactin, the levels increased over 100-fold and displayed well-defined changes as the cells proceeded through the cell cycle. The results suggest the lymphoma cells are very useful for studying biochemical events resulting from the interaction of a mitogenic polypeptide hormone and its target cell.

Adenosylmethionine Decarboxylase↗
PubMed1980

Inheritance behavior of information coding for small subunit polypeptides of fraction 1 protein.

In various genera of plants, the small subunit of fraction 1 protein is often composed of more than one kind of polypeptide; these differ in isoelectric points and amino acid composition. Previous analysis of numerous individual progeny of Nicotiana tabacum (two kinds of polypeptides), N. glauca + N. langsdorffii parasexual hybrids (three kinds) and other examples showed no change in F-1 protein composition as a consequence of alternation of generations. Experiments reported here show that absence of one number of each of the 24 different pairs of chromosomes in an N. tabacum monosomic series and also absence of the "S" pair in a nullisome did not affect F-1 protein composition. Absence of the "E" pair caused reduction in the amount of the least acidic of the two kinds of N. tabacum small subunit polypeptides. The question of how many individual progeny of self-fertile hybrids would have to be analyzed to detect segregation of genes coding for F-1 protein small subunit polypeptides, if segregation occurs, was answered by analysis of F1 hybrids between N. otophora and N. tomentosiformis, and two subspecies of N. suaveolens, together with their F2 progeny. In both cases, analysis of 16 progeny was sufficient to demonstrate a segregation pattern of two F1 hybrid type to one each of the two parental types. Therefore, in the absence of segregation, it is likely that coding information for different kinds of F-1 protein small subunit polypeptides is sequestered on heterologous chromosomes, as postulated in previous reports.

Carboxy-Lyases↗
PubMed1979

Evolution of fraction 1 protein in the genus Lycopersicon.

The large- and small-subunit polypeptide composition of fraction 1 protein contained in seven species of Lycopersicon and Solanum pennellii was determined by electrofocusing. The eight species of protein had large subunits composed of three polypeptides separated by about 0.05 pH unit, but there was no difference in the isoelectric points of the clusters of three polypeptides. By this criterion, no surviving mutations have appeared in the extranuclear DNA coding for the cluster of large-subunit polypeptides during a period of evolution which generated the eight species of plants. The genus Lycopersicon appears to be much younger than its sister genus Nicotiana in the family Solanaceae, where four types of polypeptide clusters have evolved. Three different small-subunit polypeptides whose isoelectric points are coded by nuclear DNA have arisen among the seven Lycopersicon species, and L. hirsutum and S. pennellii have proteins containing single polypeptides and are therefore considered older than L. chilense, L. chimielewskii, and L. parviflorum, whose proteins contain two polypeptides. L. cheesemanii, L. pimpinellifolium, and L. esculentum (and probably L. peruvianum) seem to be the most recently evolved species since their fraction 1 proteins have small subunits composed of three polypeptides.

Biological Evolution↗
PubMed1977

Chloroplast DNA distribution in parasexual hybrids as shown by polypeptide composition of fraction I protein.

Sixteen different mature interspecific parasexual hybrids, produced by fusing leaf protoplasts of Nicotiana glauca (G) and N. langsdorffii (L), were analyzed for fraction I protein (ribulose-1,5-bisphosphate carboxylase/oxygenase) which consists of large subunit polypeptides coded by chloroplast DNA and small subunit polypeptides coded by nuclear DNA. All the hybrids showed the combined small subunits of both parents, thus confirming the hybridity of each of the fusion products. Fourteen of the hybrids displayed the large subunit electrofocusing pattern characteristic of only one parent (eight L and six G). From one hybrid callus, two plants were regenerated, of which one had exclusively L-type large subunit and the other had exclusively G. A single plant retained a mixture of L ang G chloroplast DNA's; this later yielded six F2 progeny from one branch, all of which were G type, and three asexual progeny from another branch, all of which had the L-type pattern. In all, 46 F2 progeny and 8 different F3s were analyzed and each of these, with few if any exceptions, showed the same single subunit type as the F1 and F2 parent hybrid plants. Reasons for the rapid sorting out of the chloroplast types are discussed.

Chloroplasts↗
PubMed1977

Personality correlates of semantic habits in the deaf.

The relationships between personality characteristics and semantic habits were explored with use of The Sixteen Personality Factory Questionnaire, Form E, and a measure of semantic habits. Ss were 102 deaf male and female college students. The results, analyzed separately by sex, showed a few significant relationships. Deaf males who were emotionally less stable and affected by feelings tended to prefer positive and negative evaluations. Relaxed, tranquil, and unfrustrated deaf males tended to neglect positive and negative evaluations and to prefer categorical responses to detail ones. Serious and sober deaf females tended to neglect negative evaluations.

Adolescent↗
PubMed1976

Acoustic image in visual detection for deaf and hearing college students.

To explore the role of acoustic factors in visual detection, this study employed 40 deaf and hearing Ss. Ss were requested to cancel all the letters "e" in a passage from Treasure Island. Results were analyzed in terms of probabilities of missing a pronounced or silent e and the e in the word "the." Hearing and hard of hearing Ss were more likely to miss silent e's than pronounced e's. There was no significant difference between silent and pronounced e's for the profoundly deaf. Deaf and hearing Ss missed significantly more e's in "the" than pronounced or silent e's. The deaf, when compared to the hearing Ss, were more efficient in detecting pronounced and silent e's. They did not differ significantly from the hearing Ss in detecting the e in "the."

Acoustics↗
PubMed1975

Polypeptide composition of fraction I protein from Nicotiana glauca and from cultivars of Nicotiana tabacum, including a male sterile line.

The polypeptide compositions of fraction I protein isolated from six collections of Nicotiana glauca and from ten cultivars of N. tabacum, as well as a polyploid series and a male sterile line, have been analyzed by isoelectric focusing in polyacrylamide gel slabs containing 8 M urea. Apart from the male sterile line, none of the plants showed any variation from the species pattern of polypeptides. Fraction I protein from the male sterile Burley 21 cultivar of N. tabacum contained the two small subunit polypeptides of N. tabacum and the three large subunit polypeptides of an Australian species, probably N. megalosiphon. This indicates a changed chloroplast genome in the male sterile line in comparison to the normal fertile N. tabacum.

Genetic Variation↗