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Biomedical subjects

L Pan

Publications and source records attributed to L Pan.

At least 19 recordsLinked to original sources
PubMed1992

Insulin-mediated inhibition of the induction of tyrosine aminotransferase by dexamethasone.

Insulin-mediated regulation of glucocorticoid-induced expression of the liver-specific gene tyrosine aminotransferase was studied in a clone of the Reuber rat hepatoma cells. Insulin inhibited dexamethasone-induced chloramphenicol acetyltransferase expression from approximately 4 kb of TAT 5' flanking sequence. The degree of this inhibition was comparable to the response of the endogenous gene. A construct of approximately 3 kbp of 5' flanking sequence exhibited no significant basal expression but retained sensitivity to glucocorticoids and to insulin inhibition of the glucocorticoid response. Results of further analysis of the insulin response in deletion constructs and constructs containing glucocorticoid responsive elements ligated to a heterologous promoter suggest that in addition to the glucocorticoid response elements a region close to the start site in the TAT promoter is necessary for insulin to inhibit glucocorticoid-mediated induction of expression.

Animals↗
PubMed1992

Differential regulation of collagenase gene expression by retinoic acid receptors--alpha, beta and gamma.

The mechanisms involved in retinoic acid (RA)-mediated regulation of the collagenase gene in a rabbit synovial fibroblast cell line (HIG82) were investigated. When HIG82 cells are cotransfected with expression vectors containing cDNAs for retinoic acid receptor (RAR) alpha 1, beta 2, or gamma 1 and collagenase promoter-driven CAT reporter constructs, only RAR-gamma 1 represses basal CAT expression upon RA treatment, while RAR-alpha 1, beta 2, and gamma 1 all suppress phorbol-induced CAT expression. Thus, transcriptional regulation of collagenase by RA is mediated by RARs in an RAR-type specific manner. Using mutational and deletional analysis, we find that interaction between elements within 182 bp collagenase promoter plays an important role in this process. In addition, cotreatment with RA results in a decrease of phorbol-induced mRNA levels of fos and jun, and binding of nuclear proteins to an AP-1 oligonucleotide. Furthermore, RA-induced nuclear protein(s) specifically bind to a 22 bp sequence (-182 to -161) of the collagenase promoter. We propose that RA-mediated regulation of the collagenase gene depends on the availability and interaction of specific RARs with multiple DNA elements within the promoter and with transcription factors, including AP-1 related proteins.

Animals↗
PubMed1992

Epstein-Barr virus latent membrane protein expression by Hodgkin and Reed-Sternberg-like cells in acute infectious mononucleosis.

In the light of reports of latent membrane protein (LMP) expression by Hodgkin and Reed-Sternberg (HRS) cells, paraffin sections of tonsil (two cases), lymph nodes (eight cases; three cervical, one axillary, and four inguinal) and spleen (four cases) from 14 patients with acute infectious mononucleosis (IM) have been examined for the presence of HRS-like cells and immunostained with an antibody to LMP. Sections of the tonsils and one lymph node were also stained with a panel of antibodies which characterize HRS cells of Hodgkin's disease. The tonsils contained abundant HRS-like cells, mainly adjacent to the crypts, which were highlighted by strong LMP expression. The immunophenotype of these cells closely, but not completely, resembled that of HRS cells of Hodgkin's disease. The lymph nodes and spleens showed the typical changes of acute IM but only few LMP-positive HRS-like cells were present in the cervical lymph nodes and hardly any were present in the inguinal nodes and spleen. These findings suggest that tonsillar crypt squamous epithelium may play a role in the formation of LMP-positive HRS-like cells; these cells could be progenitors of Hodgkin's disease HRS cells and, if so, this might explain the restricted sites of presentation of Hodgkin's disease.

Acute Disease↗
PubMed1992

Activation of 5-HT1A receptor subtype in the paraventricular nuclei of the hypothalamus induces CRH and ACTH release in the rat.

Previous studies have shown that activation of the 5-HT1A receptor subtype enhances rat plasma ACTH concentration. Such receptors have been suggested to be located on CRH neuronal cell bodies in the paraventricular nuclei of the hypothalamus (PVN). In this report, microinjection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a selective 5-HT1A agonist, into the PVN increased rat plasma ACTH concentration in a dose-related manner. Similar responses were observed when two other 5-HT1A agonists, busipirone and gepirone, were used. (+/-)-Pindolol, known to have 5-HT1A antagonist properties, blocked the effect induced by an optimal dose of 8-OH-DPAT after injection into the PVN. This same dose of 8-OH-DPAT also induced a decrease of hypothalamic CRH concentration, which was completely antagonized as well by pretreatment injection of (+/-)-pindolol into the PVN. A significant inverse correlation was found between hypothalamic CRH and plasma ACTH levels. These results confirm that elevation of the plasma ACTH concentration induced by 5-HT1A receptor subtype activation is mediated by the release of CRH from the paraventricular nuclei of the hypothalamus in rats, but do not exclude other mechanisms.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1992

Plasma ammonia in patients with acute leukemia.

Plasma ammonia level (PAL) was studied in 43 cases of acute leukemia (AL). PAL was 39.21 +/- 26.2 mumol/L in normal controls and 38.8 +/- 16.6 mumol/L in leukemic patients before chemotherapy. High PAL was found in 40 cases after chemotherapy. Six cases showed clinical manifestations due to severe hyperammonemia, including dizziness, lethargy, confusion, coma and mental changes of various degree, and there was also respiratory alkalosis. After ammonia-trapping therapy, 4 of the 5 patients recovered. The authors believe that high PAL is not uncommon after chemotherapy in leukemic patients. Respiratory alkalosis and unexplained mental and neurologic changes following intensive chemotherapy are useful clues for the diagnosis of hyperammonemia syndrome. Early diagnosis and treatment with ammonia-trapping may improve the rates of remission and survival.

Adolescent↗
PubMed1992

[Investigation of rodents and Ixodes for Lyme disease and four strains of Borrelia burgdorferi first isolated from Ixodes granulatus Supino, Rattus confucianus and R. norvegicus in Fujian province].

With BSK II medium, 4 strains of Borrelia burgdorferi was isolated from Ixodes granulatus Supino, Rattus confucianus and R, novregicus, which Ixodes and Ruttus all captured from forest areas in northern of Fujian province where have found Lyme cases. These isolated strains were identified by Institute of Epidemiology and Microbiology, Chinese Academy of Preventive Medicine.

Animals↗
PubMed1992

Follicular colonization in thyroid lymphoma.

The presence of neoplastic (light chain restricted) B-cell follicles in low-grade B-cell gastrointestinal (GI) lymphoma of mucosa-associated lymphoid tissue (MALT) has been explained on the basis of specific colonization of reactive follicles by centrocyte-like (CCL) cells. Low-grade B-cell thyroid lymphomas have been included in the category of MALT lymphoma, but the frequent presence of a follicular pattern in these tumors has contributed to the view that they are follicle center cell (FCC) tumors. We have reviewed the histology and investigated the phenotype and genotype of nine cases of primary low-grade B-cell lymphoma of the thyroid, all of which were distinguished by a predominantly follicular pattern. All cases also demonstrated features of MALT lymphoma, including CCL cells and lymphoepithelial lesions. The appearances and immunohistology of the follicles were those of follicular colonization as described in GI MALT lymphoma rather than FCC follicular lymphoma. The predominant pattern of follicular colonization was replacement of the follicle center by slightly enlarged CCL cells that showed a strikingly high proliferation rate. No evidence of the t(14;18) translocation was found in any case, using the polymerase chain reaction (PCR) on DNA extracted from fresh (n = 1) or paraffin-embedded (n = 9) tissue. These findings argue against a FCC lineage for primary thyroid lymphomas and support their inclusion in the MALT category.

Base Sequence↗
PubMed1991

Lactate dehydrogenase (LDH) isoenzymes and proliferative activity of lymphoid cells--an immunocytochemical study.

In a recent immunohistochemical study, we suggested that elevation of LDH isoenzymes is generally related to cell proliferation. To explore this relationship further, we have now examined the expression of H- and M-type LDH isoenzymes immunocytochemically in human resting and mitogen-activated B and T lymphocytes. In the resting state, T lymphocytes showed strong staining for H-type LDH but showed little or no staining for M-type LDH, while B lymphocytes showed only weak staining for M-type LDH. During activation of T cells, M-type LDH started to increase when cells entered the early stages of the cell cycle. The staining intensity increased to a maximum when the percentage of the T cells at the S/G2/M phases of the cell cycle reached its peak. M-type LDH expression declined when the activated T cells returned to their resting state. Staining for H-type LDH remained strong in T cells during activation. In B lymphocytes, both H- and M-type LDH isoenzymes increased concomitantly following activation and the staining intensity also correlated well with the percentage of the S/G2/M fraction. The expression of H- and M-type LDH was also determined in fresh leukaemia and a variety of lymphoid cell lines. It was noted that cells of chronic lymphocytic leukaemia (CLL) and pro-lymphocytic leukaemia (PLL), morphologically similar to normal lymphocytes, showed a LDH staining pattern resembling that of resting B lymphocytes, while lymphoblasts in T cell acute lymphoblastic leukaemia (T-ALL), high grade B cell lymphoma and Epstein-Barr virus (EBV) transformed cell lines showed a LDH staining pattern similar to that in activated T or B lymphocytes. Taken together, our results have demonstrated a significant correlation between expression of LDH and proliferative activity of cells. Immunostaining with the MoAbs to H- and M-type LDH can, therefore, provide a useful means not only for identification of T and B lymphocytes but also for rapid evaluation of the proliferating fraction of normal and neoplastic human cell populations.

Antibodies, Monoclonal↗
PubMed1991

Expression of B-cell antigens by Hodgkin's and Reed-Sternberg cells.

Twenty frozen and 55 paraffin sections of lymphnode specimens from 55 patients with pretreatment Hodgkin's disease (nodular sclerosis Hodgkin's disease, n = 45; mixed cellularity Hodgkin's disease, n = 10) were studied by immunohistochemistry and molecular analysis to determine the phenotype of Hodgkin's and Reed-Sternberg cells (HRS). In all cases the HRS cells were CD45-, and CD30+, and in 43/55 (78%) cases they were CD15+. In 48/55 cases (87%) HRS cells were reactive with at least one B-cell marker (CD19, CD20, CD22, CDw75, MB2), 8/55 cases (14.5%) showed reactivity (mainly cytoplasmic) of a subpopulation of HRS cells with the T-cell markers CD3 and beta F1. All cases that expressed T-cell antigens were also reactive with at least one B-cell marker. In frozen sections, a minority of HRS cells in each case studied showed cytoplasmic positivity for bcl-2 protein. Rearrangement of immunoglobulin heavy chain genes was detected in one case and of T-cell receptor beta chain genes in none. The authors were unable to confirm previous reports of bcl-2 gene rearrangement in Hodgkin's disease. The results strongly support a B lymphocytic origin of HRS cells.

Antibodies↗
PubMed1991

Properties of chicken liver phosphofructokinase-2.

Phosphofructokinase-2 was purified to homogeneity from chicken livers by homogenization, polyethylene glycol fractionation and column chromatography on DEAE-Sephadex A-50 and Blue-Sepharose 4B. Some properties of the enzyme were as follows: (i) The saturation curve of the enzyme for fructose 6-phosphate showed hyperbolic and the Km of fructose 6-phosphate was affected by inorganic phosphate while Vmax was not; (ii) the binding of ATP to the enzyme was of negative cooperativity with a Hill coefficient of 0.56; (iii) the activity of the enzyme was completely lost in the presence of EDTA. The enzyme was activated by Mg2+ at low concentrations, but inhibited by Mg2+ at high concentrations; (iv) the enzyme was stable below 30 degrees C and easily lost its activity when the temperature was above 40 degrees C; (v) the activity of the enzyme was stable at the range of pH 7-9, increased at pH 9.0-9.5 and decreased when pH was over 9.5; (vi) the enzyme was sensitive to trypsin and ATP protected the enzyme against the proteolysis of trypsin.

Animals↗
PubMed1990

[Investigation on resources of the Chinese drug beimu in Gansu Province].

Based on a resources investigation and taxonomic research on the medicinal plants of Fritillaria from Gansu Province. Nine species one variety and one cultivation variety have been reported. Records and distribution of the species, together with a key for the species and a key for the powdered drug have been furnished as well.

China↗
PubMed1989

The bcl-2 gene in primary B cell lymphoma of mucosa-associated lymphoid tissue (MALT).

The bcl-2 gene rearrangement representing t(14:18) chromosomal translocation is the most frequent karyotypic abnormality in non-Hodgkin's lymphomas of follicle center-cell lineage. By using three bcl-2 DNA probes, 21 cases of non-Hodgkin's B cell lymphoma arising from gastrointestinal mucosa and eight cases of follicular lymphomas were examined. No rearrangement of the gene could be detected in the group of gastrointestinal lymphomas, although it was identified in 75% of the follicular lymphomas. The findings suggest that these two groups of lymphomas are not a family at genetic level and support the earlier suggestion that B cell lymphomas arising from gastrointestinal mucosa-associated lymphoid tissue are not of follicle center-cell lineage.

Blotting, Southern↗
PubMed1988

Is clonidine-induced diuresis mediated by atrial natriuretic factor?

The effect of intracerebroventricular (ICV) administration of clonidine on urine output, urinary sodium excretion, urinary cGMP, and plasma immunoreactive atrial natriuretic factor (IR-ANF) was studied in conscious, normally hydrated rats. Clonidine treatment evoked a significant dose-dependent increase in urine output. A 20-fold elevation was noted after the highest clonidine dose (2 micrograms/rat). The observed diuresis was accompanied by enhanced sodium excretion, which with the highest dose (2 micrograms) of clonidine increased from 1.6 +/- 0.36 to 39.4 +/- 10.5 meq/liter (P less than 0.001). Plasma IR-ANF rose from 30.7 +/- 8.8 to 113.3 +/- 32.3 pg/ml plasma 5 min after the 0.5 micrograms clonidine dose (P less than 0.05), and urinary cGMP excretion was augmented from 8.49 +/- 4.29 to 27.7 +/- 5.0 pmol/min 1 h after 0.5 micrograms clonidine (P less than 0.05). Pretreatment with peripherally administered anti-ANF serum abolished the diuretic effect of intracerebroventricularly administered clonidine; urine output decreased from 1.49 +/- 0.41 to 0.42 +/- 0.21 ml/h. The urinary cGMP level after anti-ANF serum treatment fell from 25.0 +/- 7.56 to 7.1 +/- 3.5 pmol/min (P less than 0.05). Peripheral pretreatment with the alpha 2-antagonist yohimbine or the opioid antagonist naloxone partially abolished clonidine's diuretic impact: urine output dropped from 1.91 +/- 0.55 to 0.42 +/- 0.18 and 0.46 +/- 0.18 ml/h (P less than 0.05), respectively. At the same time, plasma IR-ANF decreased from 113.3 +/- 32.2 to 30.3 +/- 11.4 after yohimbine and to 24.6 +/- 12.1 pg/ml after naloxone treatment (P less than 0.05). These data suggest that ANF may be involved in the mechanism of diuresis of centrally applied clonidine, which appears to enhance ANF release through its central stimulation of opiate and alpha 2-adrenergic receptors.

Animals↗
PubMed1987

Independent effects of aldosterone and potassium on induction of potassium adaptation in rat kidney.

We examined the independent effects of a high potassium diet and increased aldosterone levels on the development of renal potassium adaptation. This condition is defined by the increased ability of the kidneys to excrete an acute infusion of potassium. Rats were adrenalectomized (ADX) and received aldosterone at basal levels (0.5 microgram/100 g X d) or at high levels (2.0 micrograms/100 g X d) for 10 d. In each experimental group, animals received either a control diet or a high potassium diet. In ADX animals with basal aldosterone levels, a high potassium intake increased but did not completely restore the ability to excrete potassium and induced proliferation of the basolateral membrane of principal cells in the collecting tubule (i.e., morphologic adaptation). In contrast, increased aldosterone did not induce functional adaptation. Elevated aldosterone and dietary potassium intake were required to produce functional potassium adaptation indistinguishable from that in potassium-loaded, adrenal-intact animals.

Adaptation, Physiological↗