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Biomedical subjects

H L Li

Publications and source records attributed to H L Li.

At least 91 records · Page 5Linked to original sources
PubMed1992

Differential susceptibilities of U-937 cell clones to infection by human immunodeficiency virus type 1.

Single-cell clones derived from the U-937 monocytic cell line were studied for susceptibility to infection by human immunodeficiency virus type 1 (HIV-1). Of four such clones, we found that three (UC12, UC14, and UC18) supported replication of HIV-1 more efficiently than parental U-937 cells, as measured by reverse transcriptase activity and p24 core antigen production. In contrast, another clone (UC11) showed only baseline infection throughout an 8-week culture period, before finally becoming positive for expression of viral antigen. This differential susceptibility to infection directly correlated with accumulation of intracellular viral DNA. Furthermore, the UC11 clone expressed lower levels of Sendai virus-inducible tumor necrosis factor alpha mRNA than did the UC12 or UC18 clones. Susceptibility to infection did not correlate with expression of cell surface CD4, since all clones expressed similar levels of CD4 mRNA and surface membrane CD4 protein. Prior exposure of both susceptible UC18 and resistant UC11 clones to Leu3a antibody completely blocked infection by HIV-1, suggesting that no other independent receptors were recognized by the virus.

Blotting, Southern↗
PubMed1992

Two new anti-rat macrophage monoclonal antibodies.

There are relatively few monoclonal antibodies (MAbs) to rat monocyte/macrophages available. We describe here 2 new such antibodies. The first, 109.2, recognizes most rat monocyte/macrophages and all polymorphs. The antigen recognized by this antibody is upregulated by 15 mins exposure to PMA (Phorbol myristate acetate) but down regulated by overnight exposure to LPS (lipopolysaccharide). It is probably an adhesion molecule and is likely to represent the rat equivalent of CD11b. The second antibody, 112.1, recognizes lysozyme in rat macrophages, particularly alveolar macrophages. In addition it also recognizes lysozyme in hen, rabbit and human macrophages. It also recognizes lysozyme in other tissues such as Paneth cells and proximal renal tubular cells.

Animals↗
PubMed1992

[Zero-crossing derivative spectrophotometry for the determination of three components in paracetamol compound tablets].

The zero-order derivative absorption spectra of aspirin, paracetamol and caffeine are closely overlapping. In this paper, a zero-crossing derivative spectrophotometry combined with simultaneous equations is proposed for the determination of the three components in a mixture without the need of prior separation. Satisfactory results were obtained. The method is reproducible, accurate and rapid. Calculation is not complicated. This method could be applied to biological fluid analysis.

Acetaminophen↗
PubMed1991

Activated (IL-2R+) intraglomerular mononuclear cells in crescentic glomerulonephritis.

We recently reported evidence for the involvement of local cellular immune activation in the immunopathogenesis of human IgA nephropathy, particularly in cases of IgA disease featuring crescent formation. In the current study, using monoclonal antibodies, we investigated whether mononuclear cells bearing receptors for interleukin 2 (IL-2R+ MNC) were present within glomeruli or associated crescents in biopsies from patients with crescentic glomerulonephritis (greater than 60% crescents, N = 19), IgA disease with crescents (N = 9), or other types of proliferative glomerulonephritis with crescents (10 to 44%, N = 6), compared with normal control kidneys (N = 10). Biopsies were further classified into those showing active (cells, fibrin) (N = 15) or inactive (sclerosed) crescents (N = 19), to determine whether IL-2R+ MNC were particularly associated with active crescent formation. Few leucocytes were found within glomerular tufts of normal kidneys (2.4 +/- 0.7 cells/glomerular cross-section; mean +/- SEM). By contrast, in biopsies from patients with active crescentic glomerulonephritis, total intraglomerular tuft leucocytes were increased to 14.0 +/- 1.7 (P less than 0.01 vs. normal kidneys), largely due to increased numbers of intraglomerular monocytes (10.4 +/- 1.1, P less than 0.01) and T cells (3.7 +/- 0.6, P less than 0.01). Biopsies with active crescents also contained significantly increased numbers of intraglomerular tuft IL-2R+ MNC (4.0 +/- 0.7, 29% of total intraglomerular leucocytes), and there was a strong correlation between the numbers of intraglomerular IL-2R+ MNC and T cells (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Count↗
PubMed1991

Cloning and expression of propionyl acylase gene of Streptomyces mycarofaciens mutant.

The midecamycin producer, S. mycarofaciens mutant, which has propionyl acylase activity, can convert spiramycin into propionyl spiramycin. Plasmid pIJ702 was used as a vector for the cloning of propionyl acylase gene. After shot-gun cloning, the DNA fragments of the mutant were cloned in S. lividans TK54. The results of TLC and HPLC showed that No.9 transformant can convert spiramycin into propionyl spiramycin. It demonstrated that the propionyl acylase gene was cloned and expressed in S. lividans TK54. The insert fragment of No.9 recombinant plasmid is about 4.16 kb. Southern hybridization showed that the fragment originated from S. mycarofaciens mutant. The restriction endonuclease map of No.9 recombinant plasmid was constructed.

Acyltransferases↗
PubMed1990

Mononuclear cell activation and decreased renal function in IgA nephropathy with crescents.

Our previous immunohistologic studies with monoclonal antibodies (mAb) showed that glomerular and interstitial accumulations of mononuclear cells (MNC) were common features of many types of proliferative glomerulonephritis, especially crescentic glomerulonephritis. The current study examined a series of patients with crescentic IgA disease, since IgA disease in general has a highly variable course and the presence of crescents is one indicator of likely progression to end-stage renal failure. We compared the intraglomerular and interstitial infiltrates within biopsies from patients with crescentic IgA nephropathy (N = 5) versus those with noncrescentic IgA (N = 18), or normal controls (N = 10). Few leucocytes were found within glomeruli of normal (2.4 +/- 0.7 cells/glomerular cross section) (mean +/- SEM) or noncrescentic IgA disease biopsies (3.8 +/- 0.7), and no activated MNC bearing receptors for interleukin-2 (IL-2R) were detected. By contrast, in crescentic IgA disease, glomerular leucocytes were increased (5.1 +/- 0.6, P less than 0.01), due to increased monocyte (3.1 +/- 0.9, P less than 0.01) and T cell (1.4 +/- 0.4, P less than 0.01) infiltration, and IL-2R + MNC were then observed (1.2 +/- 0.5, P less than 0.05). Studies of interstitial cells showed small numbers of leucocytes within normal kidneys (101 +/- 16/mm2). Biopsies from noncrescentic IgA disease showed a fivefold increase in interstitial MNC infiltration (total leucocytes 565 +/- 105/mm2, P less than 0.01), due to an influx of T cells (283 +/- 59/mm2, P less than 0.01) and monocytes (120 +/- 32/mm2, P less than 0.01), and including a mean of 20% IL-2R+ MNC (114 +/- 29/mm2, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

A glucocorticoid response element enhances transcription of a methionine tRNA gene in cis and trans.

In vitro transcription experiments using a Xenopus laevis cell-free extract have demonstrated that a DNA fragment containing a glucocorticoid response element (GRE) significantly enhances the expression of a methionine tRNA gene. This stimulation can be observed when the element is located in cis or trans. In the cis configuration, the element can be located 2900 basepairs from the gene and still display transcriptional enhancement. In trans, the enhancement can occur at a low element to template molecular ratio. The nucleosome positioning and chromatin structure near the tRNA gene appear to be unaffected by the presence of the long terminal repeat of the mouse mammary tumor virus which contains the GRE. Taken together, these data suggest that GREs can stimulate transcription of hormonally unresponsive genes, perhaps by providing a "molecular sink" to which inhibitors may bind. Further experimentation may reveal a correlation between these in vitro studies and in vivo gene regulation.

Animals↗
PubMed1989

[Relationship between the content of central substance P and the analgesic effect of electroacupuncture in rats].

Substance P(SP) immunoreactivity in the rat brain and spinal cord were measured by radioimmunoassay and studied to correlate with the analgesic effect induced by electroacupuncture (EA). The results showed following: (1) There was a significant elevation in SP levels sn the hippocampus, hypothalamus and striatum after 30 min of EA. There was a markedly fall in the spinal cord. Statistical analysis revealed a positive correlation between the EA effect and the SP content in hypothalamus, striatum and statistical analysis revealed a correlation. In the spinal cord. (p less than 0.01), while the SP content in the hippocampus exhibited a similar degree of elevation in non responsive and good responsive animals to EA stimulation. (2) SP levels in the hippocampus, hypothalamus and striatum were increased by electroacupuncture stimulation (3v). The frequency of 1.5Hz was no obvious difference as compared with 100Hz in the effects on brain SP content. (3) SP content in the spinal cord decreased only using electroacupuncture stimulations of combination of higher intensity (3v) and higher frequency (100 Hz). (4) This effect could be blocked by the naloxone (i.p) and LSD (icv), but icv injection of Met-enkephalin antibodies had no affects on them.

Acupuncture Analgesia↗
PubMed1989

Immunopathological study on human cartilage allografts.

The fate of human cartilage allografts and the mechanism of its kinetical development were studied histopathologically and immunohistologically. After transplantation, the grafts underwent necrosis, calcification and were partially invaded by osteoplastic tissue of the host and eventually replaced by bone tissue. Thus, the contour of the transplanted cartilage was kept partially by the living cartilage and the newly-formed osseous tissue. The grafts were surrounded initially by granular tissue and then by scar tissue, in which numerous T cells and a few macrophage infiltrates were noted. In T cells, T4+ lymphocytes predominated but T8+ cells accounted for a small number. B cells were not found within the infiltrates. Most of the infiltrating cells expressed 12 antigens, indicating that the majority of T cells were activated. It was concluded that T lymphocytes mediated cellular immunity played an important role. The chondrocytes of the cartilage did not express HLA I and II antigens before transplantation, but one month later, the living chondrocytes became HLA I and II antigens positive, and the antigen expression became stronger with the elapse of time; this might be induced by lymphokins, especially by interferon produced by the infiltrating lymphocytes. Such an expression of MHC antigens on chondrocytes might contribute to the further enhancement of immunorejection.

Adult↗
PubMed1987

Ultrastructural localization of 2-naphthylthiol acetate nonspecific esterase in human blood cells and leukemic cells.

Nonspecific esterase activity was localized ultrastructurally within normal and leukemic hematopoietic cells by the use of 2-naphthylthiol acetate (NTA) as a substrate. NTA esterase activity was identified in all cell lines, although mononuclear phagocytes contained the most abundant activity. Monocytes, macrophages, young granulocytes, eosinophils, basophils, megakaryocytes, and platelets showed reaction products primarily associated with the membranes of cell granules, mitochondria, rough endoplasmic reticulum, and perinuclear cisternae. Lymphocytes demonstrated focal uneven staining in perinuclear cisternae and endoplasmic reticulum, with only occasional cytoplasmic reactions. Erythroblasts showed the most distinctive staining pattern with predominance of large amounts of reaction product within the perinuclear space in a ring-like distribution. Examination of the staining pattern in 42 cases of leukemia and 2 cases of malignant lymphoma demonstrated only limited usefulness as a diagnostic aid.

Blood Cells↗