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Biomedical subjects

C N Sun

Publications and source records attributed to C N Sun.

At least 19 recordsLinked to original sources
PubMed1998

Molecular cloning and heterologous expression of a glutathione S-transferase involved in insecticide resistance from the diamondback moth, Plutella xylostella.

Four glutathione S-transferase (GST, EC 2.5.1.18) isozymes have been characterized in the larvae of the diamondback moth (DBM), Plutella xylostella L., a cosmopolitan insect pest of crucifiers. This work aimed at cloning and heterologously expressing the cDNA of DBM GST-3, an isozyme involved in this insect resistance to some organophosphorus insecticides, and studying the molecular basis for its increased expression in the resistant strains. Reverse-transcription polymerase chain reaction (RT-PCR) using midgut mRNA from a methyl parathion resistant MPA strain and degenerate primers complimentary to the N-terminal and internal amino acid sequences of GST-3 generated a 128 bp DNA product. A clone of 809 bp, obtained by screening a midgut cDNA library of MPA strain using this PCR product as probe, encoded a protein of 216 amino acids (calculated Mr 24,083 and pI 8.50). This GST of DBM, PxGST3, shared the highest (46.3%) amino acid sequence identity, among insects, to MsGST1 of Manduca sexta. PxGST3 mRNA level was considerably higher in MPA than in susceptible strains, and Southern blots suggested that gene amplification was probably not involved in the increased expression of this GST isozyme. Enzymatically active PxGST3 expressed heterologously in E. coli exhibited similar biochemical and toxicological properties as GST-3 purified from DBM larvae. It is the first cloned GST with a well-defined role in insecticide resistance.

Amino Acid Sequence↗
PubMed1984

Unusual membrane bound intranuclear inclusions in human fibroblasts infected with herpes simplex.

Examination of brain tissue taken at autopsy from a 55-year old male showed the presence of herpes simplex viral antigen by immunofluorescence techniques. A suspension of this tissue was inoculated into cultures of human diploid fibroblasts. After 72 h, viral particles at different stages of development were seen inside the nuclei. Envelopment of the viral particles seemed to occur in association with the nuclear membranes, endoplasmic reticulum, cytoplasmic vacuoles and plasma membranes. Severely altered nuclear membranes, with as many as 4 to 8 layers of nuclear envelope, emphasized the common occurrence of membrane reduplication associated with herpes simplex infection. Unusual membrane-bound, dense, rounded inclusions, 100 to 500 nm in diameter, were present in the nucleus. These inclusions apparently were formed between the inner and outer lamellae of the nuclear membrane.

Antigens, Viral↗
PubMed1983

Ultrastructural study of corpora amylacea in human thyroid gland.

Large cytoplasmic inclusions, corpora amylacea, were found in the follicle epithelial cells of a thyroid with medullary carcinoma. They were varied in size from 1.5 to 10 microns in dimension and the shapes were from fusiform to irregularly formed. Fine fibrils 8 to 23 nm in diameter were randomly arranged within the inclusions. The findings from our work and experience of others suggest that the inclusion bodies may be nonspecific or that an accumulation of abnormal cellular inclusions could be caused by various illness.

Adult↗
PubMed1981

Scanning electron microscopy of Legionella pneumophila in clinical tissue.

Scanning electron microscopy (SEM) is a valuable technique for rapid detection of the presence of microorganisms, for determination of their three-dimensional morphology and topology and for identification of their anatomical sites. It has been used for these purposes in Legionnaires' disease with three patients at autopsy in an investigation of Legionella pneumophila in situ. In two cases the study was restricted to lung, and in the third case tissues from extra-pulmonic sites were examined in addition to lung. Microorganisms in good condition of surface preservation were found in lung, tracheal lymph node and heart. The work has shown that the bacterium is pleomorphic, that it can be either rod or sausage-shaped and that it can possess a smooth, dimpled or wrinkled surface, with or without small terminal or lateral blebs. Binary fission was often seen and there was some minimal evidence of flagella in clinical specimens. Well preserved bacteria were found in lung both intra- and extracellularly.

Heart↗
PubMed1979

Microorganisms seen by scanning and transmission electron microscopy in Legionnaires' disease from human lung.

In addition to several anomalous structures, other general forms of definitely rod-shaped microorganisms have been found by scanning and transmission electron microscopy in the lung tissue taken at autopsy from a patient who succumbed to confirmed Legionnaires' disease with extensive necrotizing lobar pneumonia. The microorganisms were greatly varied in size and shape. They were micrographed in the act of fission. These forms have been found to some extent throughout the tissue. No nickel was demonstrated, either in the lung tissue or in the microorganisms.

Humans↗
PubMed1979

Annulate lamellae in human tumor cells.

Annulate lamellae have been found in a primitive neuroectodermal tumor, a metastatic cerebellar tumor, a testicular seminoma, a retinoblastoma and three melanomas. These annulate lamellae are arranged in stacked parallel arrays in the cytoplasm of tumor cells. The number of annulate lamellae observed to comprise a single stack varies from 2--4 in the seminoma tumor to 5--18 in the cerebellar tumor. Although the functional significance of annulate lamallae is still unknown, in many instances they have been found to be continuous with rough-surfaced cisternae of the endoplasmic reticulum and ribosomes have been demonstrated on the surface of annulate lamellae. This may suggest that annulate lamellae participate in protein synthesis.

Cerebellar Neoplasms↗
PubMed1979

An ultrastructural demonstration of the agent of Legionnaires' disease in the human lung.

The authors have provided ultrastructural demonstration from human material of a small rod shaped organism that represents the causative agent of Legionnaires' disease. The organisms are found mainly in intracytoplasmic vacuoles of alveolar cells. They have a thin outer cell wall and a more delicate plasma membrane. On the basis of morphology, arguments are presented to classify these unusual organisms as rickettsia-like.

Bacteria↗
PubMed1979

Interactions between human granulocytes and Blastomyces dermatitidis.

We studied interactions in vitro between human granulocytes and the yeast-like form of Blastomyces dermatitidis, because granulocytes are prominent in the host response to systemic blastomycosis. In Boyden chamber assays, broth culture filtrates of B. dermatitidis contained levels of granulocyte chemotactic activity that were significantly higher than those present in similar culture filtrates of Histoplasma capsulatum and Cryptococcus neoformans, two fungi that characteristically do not elicit granulocytes in infected tissues. Microscopic study, including electron microscopy, demonstrated that granulocytes phagocytosed B. dermatitidis promptly and efficiently. Moreover, granulocytes emitted light (chemiluminescence) at a brisk rate during phagocytosis of B. dermatitidis, indicating activation of intracellular metabolic pathways. However, fungicidal assay showed that granulocytes (1:1 cell-yeast ratio, 10% serum) killed only 29% of the B. dermatitidis inoculum during 3 h of incubation. Taken together, these findings suggest that there is disparity between phagocytosis and intracellular killing of B. dermatitidis by human granulocytes, perhaps because of resistance of this fungus to granulocyte microbicidal mechanisms.

Blastomyces↗
PubMed1977

Spectrum of ultrastructural patterns of renal cell adenocarcinoma.

The ultrastructure of renal cell carcinoma was studied in 6 patients. This study demonstrated a spectrum of ultrastructural patterns ranging from the classic electron microscopic features of granular cell carcinoma at one extreme, to those of clear cell carcinoma at the other extreme. Other tumors demonstrated intermediate features. There was reasonably good correlation between the light microscopy and electron microscopy. Unusual findings of connective tissue banded structures and basement membrane branching were demonstrated.

Adenocarcinoma↗
PubMed1977

Unusual degenerated forms of human sperms.

Many spheric bodies with radiating, needle-like filaments are present in semen of patients with fertility problems. These bodies are most likely degenerated sperm. The intermediate forms and a sequential series of degeneration are discussed.

Cell Nucleus↗