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Biomedical subjects

T Sun

Publications and source records attributed to T Sun.

At least 127 records · Page 7Linked to original sources
PubMed1995

Morphological, ultrastructural, and genetic characterization of an unusual T-cell lymphoma in a patient with sinus histiocytosis with massive lymphadenopathy.

Sinus histiocytosis with massive lymphadenopathy (SHML) is a rare benign disease of unknown etiology. It is rarely associated with malignant lymphoma. This report documents the first case of a T-cell lymphoma, which developed in a patient with a 10-year history of SHML. The disease was complicated by hypereosinophilia and massive retroperitoneal lymphadenopathy. Histological examination of a cervical lymph node biopsy during the terminal phase identified a lymphoma composed of cells with morphological plasmacytoid features. Ultrastructurally, the tumor cells showed poorly developed cytoplasm, nuclei with peripheral chromatin clumping, and inconspicuous nucleoli. Cytogenetic studies showed two related clones. On immunohistochemical staining tumor cells were positive with monoclonal antibodies (mAb) CD3 and CD45RO. Southern blotting analysis identified clonal rearrangements in the T-cell receptor (TCR) alpha, beta and gamma genes. Thus, T-cell lineage of the tumor cells was established. In situ hybridization of interleukin-2 (IL-2) and interleukin-5 (IL-5) cDNA probes on tissue sections identified the synthesis of IL-5 by the eosinophils, suggesting an autocrine pathway of eosinophilopoiesis leading to hypereosinophilia in this patient.

Clone Cells↗
PubMed1995

Cloning and expression of cytochrome P450(11 beta) of porcine adrenal cortex.

Four cDNA clones were isolated from a porcine adrenal gland library by using a bovine cytochrome P450(11 beta) cDNA fragment as a probe. Nucleotide sequences of the four clones overlapped with each other. The deduced amino acid sequences indicated that these clones were derived from a porcine P450(11 beta) cDNA. Consecutive alignment of these clones covered almost 70% of a coding region of the cDNA, but its 5'-terminus was missing. The adrenal mRNA was reverse-transcribed, and polymerase chain reaction was used to obtain a cDNA fragment including the 5'-terminus. A cDNA constructed from this fragment and the isolated four fragments covered the entire apparent open reading frame of the enzyme, which was thus concluded to comprise 503 amino acids including a putative extension peptide of 24 amino acids at the NH2-terminus. The amino acid sequence was 82% identical to that of bovine P450(11 beta)-3. The cDNA was transfected into COS-7 cells, and steroidogenic activity of the cells was measured. The cells not only converted 11-deoxycorticosterone to corticosterone and 18-hydroxycorticosterone, but also produced aldosterone. Thus we conclude that the primary sequence of porcine P450(11 beta) which plays a role in the biosynthesis of glucocorticoids as well as mineralocorticoids was determined.

18-Hydroxycorticosterone↗
PubMed1995

Cytochrome P450(11 beta): structure-function relationship of the enzyme and its involvement in blood pressure regulation.

Cytochrome P450(11 beta) is deeply involved in the final steps of biosynthesis of mineralocorticoids. This paper deals with following issues about this enzyme. (1) The structure and function of the enzymes of various animal species are discussed. By making alignment of amino acid sequences of the enzymes, we identified peptide domains essential for the enzyme actions such as a putative steroid binding domain and a heme binding region. Estimates of molecular similarity among the P450(11 beta) family enzymes suggested that the enzymes having both 11 beta-hydroxylation activity and aldosterone (ALDO) synthetic activity of certain animals such as frog, cattle and pig are more similar to the ALDO synthases of the other animals, such as rat, mouse and human, than the 11 beta-hydroxylases of these animals. (2) The molecular nature of the P450(11 beta) family enzymes of genetically hypertensive rats as well as adrenal regeneration hypertension (ARH) rats is examined. (i) Mutation was found in the P450(11 beta) gene of Dahl's salt-resistant normotensive rat. Steroidogenic activity expressed by the mutated gene accounted well for abnormal plasma levels of steroid hormones in this rat. (ii) 11 beta-, 18- and 19-Hydroxylation activities of adrenal mitochondrial prepared from spontaneously hypertensive rat (SHR), Wistar-Kyoto rat (WKY), and stroke-prone (SP)-SHR were not significantly different from each other. Levels of mRNA of ALDO synthase in adrenal glands of 50-week-old SHR was significantly lower than those of 10-week-old SHR, WKY and SHR-SP. (iii) No significant difference in 19-hydroxylation activity was found between adrenal mitochondria prepared from ARH rat and those from control rat. The level of message of ALDO synthase was lower in adrenal glands of ARH rat.

Aldosterone↗
PubMed1995

Immunization with interleukin-2/interferon-gamma double cytokine-secreting allogeneic fibroblasts prolongs the survival of mice with melanoma.

LM mouse fibroblasts (H-2k) were modified for the expression of (antibody-defined) melanoma-associated antigens (MAA) and the secretion of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) (RLBA-IL-2/IFN-gamma cells). The cell construct was tested for its immunogenic properties in C57BL/6 mice (H-2b) with B16 melanoma. The results indicated that the survival of mice injected with a mixture of B16 cells and the modified, double cytokine-secreting fibroblasts was significantly longer than that of mice injected with B16 cells and LM cells modified for the expression of MAA and the secretion of IL-2 or IFN-gamma alone (RLBA-IL-2 or RLBA-IFN-gamma cells). Both natural killer/lymphokine-activated killer (NK/LAK) cells and Lyt-2.2 + CTLs with anti-melanoma cytotoxic activities were predominant in mice immunized with the double cytokine-secreting cells. B16 melanoma cells persisted in mice treated with RLBA-IL-2 cells (B16-R3). The B16-R3 cells were resistant to anti-melanoma effector cells from mice immunized with RLBA-IL-2 cells. The recurrent melanoma cells were deficient in the expression of MHC class I determinants. Class I expression by B16-R3 cells was increased if they were incubated in medium conditioned by the growth of IFN-gamma-secreting RLBA-IL-2/IFN-gamma or RLBA-IFN-gamma cells. After incubation, the sensitivity of B16-R3 melanoma cells to immune-effector cells from mice immunized with RLBA-IL-2 cells was restored. The survival of mice bearing low MHC class I-expressing B16-R3 cells, treated RLBA-IL-2/IFN-gamma cells, was determined. The treated animals survived significantly longer than mice with B16-R3 melanoma treated with RLBA-IL-2 cells. Similar results were obtained for mice with B16-R3 melanoma treated with RLBA-IFN-gamma cells. We postulate that immunization of mice with IL-2/IFN-gamma double cytokine-secreting cells stimulated multiple anti-melanoma effector mechanisms. Analogous to the enhanced therapeutic anti-tumour effects of combination chemotherapy, it was likely that treatment with a cellular immunogen engineered to stimulate more than one effector mechanism resulted in the elimination of larger numbers of tumour cells than treatment with an immunogen that stimulated a single effector mechanism alone.

Animals↗
PubMed1995

Interleukin-2-secreting mouse fibroblasts transfected with genomic DNA from murine neoplasms induce tumor-specific immune responses that prolong the lives of tumor-bearing mice.

Genetic alterations are a common feature of the malignant phenotype. Among other properties, altered genes may be responsible for invasion and metastasis, as well as for resistance to chemotherapeutic agents. Under appropriate circumstances, the products of other altered genes expressed by malignant cells may act as tumor-associated T-cell epitopes, capable of provoking antitumor immune responses. As a novel means of augmenting the immunogenicity of the gene products, unfractionated, sheared genomic DNA from various tumor cell lines (B16F1 melanoma, B16F10 melanoma, MOPC-315 plasmacytoma, C1498 lymphoma, or J558 myeloma), or from non-neoplastic liver cells of tumor-free mice, was transfected into LM cells, a mouse fibroblast cell-line (H-2k) that had been modified previously by retroviral gene transfer to secrete interleukin-2 (IL-2). The IL-2-secreting transfected cell populations were then tested for their immunogenic properties toward B16F1 (H-2b) or C1498 (H-2b) cells in syngeneic C57BL/6 mice. The antitumor responses were specific for the type of tumor from which the DNA was obtained. The survival of C57BL/6 mice injected with a mixture of viable B16F1 cells and IL-2-secreting LM cells transfected with DNA from B16F1 cells was significantly prolonged. In a similar manner, the survival of C57BL/6 mice injected with a mixture of C1498 cells and IL-2-secreting LM cells transfected with DNA from C1498 cells was prolonged as well. The immunity was mediated predominantly by CD8+ and natural killer/lymphokine-activated killer (NK/LAK) cells. These data raise the possibility that a cell line altered previously for cytokine secretion may be readily modified to provide immunologic specificity for the neoplasms of individual cancer patients.

Animals↗
PubMed1994

High-level expression and functional reconstitution of Shaker K+ channels.

Voltage-gated K+ channels were expressed in COS cells transiently transfected with a plasmid carrying a cDNA for an inactivation-removed Shaker K+ channel driven by an adenovirus promoter. Channel expression was followed by immunological detection, binding of radioactive charybdotoxin (CTX), and functional reconstitution into planar lipid bilayers. About 10(7) channels per transfected cell are expressed on the plasma membrane. The expressed channels are glycosylated and competent to bind CTX with the expected characteristics. Channels observed after insertion into planar lipid bilayers displayed the voltage-dependent gating, conduction, and ion selectivity behavior expected for this channel. Channels were solubilized in several detergents without loss of CTX binding activity. The results make plausible a systematic attack on the purification of milligram-level amounts of functional K+ channels from a heterologous expression system.

Adenoviridae↗
PubMed1994

Geographic variation of p53 mutational profile in nonmalignant human liver.

Fifty-eight percent of hepatocellular carcinomas (HCCs) from Qidong, China, contain an AGG to AGT mutation at codon 249 of the p53 tumor suppressor gene, a mutation that is rarely seen in HCCs from Western countries. The population of Qidong is exposed to high levels of aflatoxin B1 (AFB1), a fungal toxin that has been shown to induce the same mutation in cultured human HCC cells. To investigate the role of AFB1 and of these p53 mutations in hepatocarcinogenesis, normal liver samples from the United States, Thailand, and Qidong (where AFB1 exposures are negligible, low and high, respectively) were examined for p53 mutations. The frequency of the AGG to AGT mutation at codon 249 paralleled the level of AFB1 exposure, which supports the hypothesis that this toxin has a causative--and probably early--role in hepatocarcinogenesis.

Aflatoxin B1↗
PubMed1994

Splenic lymphoma with circulating villous lymphocytes: report of seven cases and review of the literature.

Splenic lymphoma with villous lymphocytes (SLVL) is a relatively new entity with only a few reports published. We report seven cases of SLVL with detailed clinicopathologic and comprehensive immunophenotypic studies to further characterize this lymphoma, which is frequently confused with hairy cell leukemia and other low-grade B-cell lymphoid neoplasms. The diagnostic criteria we used include 1) prominent splenomegaly, 2) insignificant or no lymphadenopathy, 3) lymphocytosis without leukopenia, 4) presence of circulating villous lymphocytes, 5) characteristic cytologic and histologic features, and 6) specific phenotypic and cytochemical findings. Our studies show that SLVL does not represent a pure entity but rather a morphologically heterogeneous group of low-grade lymphomas with various cytologic and histologic features. Although immunophenotyping is helpful in differential diagnosis, multiparameter studies are necessary to confirm the diagnosis. In our series, only two patients died of SLVL, who probably developed transformation to a higher-grade lymphoma.

Aged↗
PubMed1994

Long-term results of microvascular decompression for trigeminal neuralgia with reference to probability of recurrence.

Sixty-one patients with trigeminal neuralgia who underwent microvascular decompression were analysed. Vascular compression of the trigeminal nerve root was found in all cases. The recurrence rate of pain in this series was 18% with an average follow-up of 80 months (range: 13 to 126 months). Ten patients developed recurrence of their trigeminal neuralgia during follow-up. Fifteen factors, including the clinical and operative findings in the pain-free patients versus the 10 patients with recurrence were analysed. Only the patients with venous compression singly or in combination with arteries were significantly related to recurrence. There was no relationship between recurrence and the duration of symptoms or the degree of compression. Based on vascular compression as the sole cause of TN, the results and interesting findings can not be explained. With reference to the hypothesis that vascular compression is only one of at least two causative factors for the development of trigeminal neuralgia, it is suggested that the intrinsic lesion in trigeminal neuralgia may be responsible for late recurrence.

Adult↗
PubMed1994

Current topics in protozoal diseases.

The author reviews seven protozoal diseases, emphasizing the current development but also briefly reviewing the basic knowledge in epidemiology, parasitology, clinical features, pathology, and laboratory diagnosis. Cryptosporidiosis, microsporidiosis, and cyclosporiasis, which are newly discovered diseases in humans, and pneumocystosis, toxoplasmosis, and isosporiasis, which are important opportunistic infections in patients with acquired immunodeficiency syndrome, are discussed. The author also presents acanthamoeba keratitis, a disease seen mainly in contact lens wearers that is expected to have a higher prevalence in the near future.

Humans↗
PubMed1994

Engineering a uniquely reactive thiol into a cysteine-rich peptide.

Cysteine mutagenesis for the purpose of chemical labelling was applied to the K+ channel neurotoxin charybdotoxin, a 37-residue peptide with six functionally essential cysteines. An additional 'spinster cysteine' was introduced at a position far away in space from the toxin's known interaction surface where it contacts its K+ channel receptor. Despite the presence of the extra unpaired cysteine residue, the toxin still folds efficiently and may be labelled by fluorescent and radioactive reagents to give a functionally competent toxin.

Animals↗
PubMed1994

[The cloning of threonine operon in vivo and mutagenesis in vitro in E. coli].

Report here was the selection of the E. coli strain producing 1.2% threonine. The wild type threonine operon was cloned in vivo and subcloned in vitro. The subclone was mutagenizied in vitro and a clone pTHR12-9-1 producing threonine was obtained. Also the effect of pTHR12-9-1 on threonine yield of hosts producing different amount of threonine was studied. We found that pTHR12-9-1 could promote the production of threonine in lower yield hosts, but it reduced the production of threonine in higher yield hosts. The phenomenon was discussed.

Cloning, Molecular↗