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Biomedical subjects

L Yang

Publications and source records attributed to L Yang.

At least 721 records · Page 40Linked to original sources
PubMed1993

A histological morphometric study of nuclear size in benign and malignant neoplasms of the human cheek.

This report describes the application of simple morphometric methods to generate quantitative data on nuclear size from tissue sections of normal, benign and malignant oral epithelium of the cheek. Measurements of nuclear areas of basal and spinous cells from cheek mucosa were made on haematoxylin and eosin-stained sections using a Zeiss VIDAS image analyser. The lesions examined comprised benign squamous cell papillomas and islands of cells from invasive squamous cell carcinomas. Normal control epithelium was obtained from the biopsy margins of non-neoplastic lesions. The nuclear areas (AN) were obtained by direct measurement whereas the nuclear diameters (DN) were determined automatically. In both basal and spinous strata, values for both these nuclear parameters were lowest in normal tissue and increased progressively through benign papillomas, with the highest values being found invariably in carcinomas. Statistically significant differences were detected between both normal and carcinoma and between papilloma and carcinoma. The morphometric parameters AN and DN are of value in distinguishing benign from malignant lesions of the human cheek.

Carcinoma, Squamous Cell↗
PubMed1993

G-protein specificity in signaling pathways that mobilize calcium in insulin-secreting beta-TC3 cells.

Fuel- and receptor-induced signal transduction pathways were investigated in beta-TC3 cells, an insulin-secreting cell line. An increase of glucose concentration from 0 to 15 mM and stimulation with 0.5 mM carbachol resulted in up to a twofold increase in insulin secretion by beta-TC3 cells, and their simultaneous addition increased insulin release eightfold. In single fura 2-loaded cells, a potentiating effect of carbachol was also observed on glucose-induced intracellular Ca2+ mobilization. Immunoblotting with antibodies raised to the COOH-terminal of G-protein alpha-subunits showed that G alpha i, G alpha o, and G alpha q are present in beta-TC3 cells in commensurable quantities. The novel technique of microinjection of anti-G alpha antibodies into single beta-cell was used to probe the functional role of these G-proteins. Microinjection of anti-G alpha i antibodies into beta-TC3 cells had no effect on glucose- and carbachol-induced Ca2+ mobilization. However, anti-G alpha q completely inhibited the Ca(2+)-mobilizing effect of carbachol, but not of glucose, within 5 min. Microinjection of anti-G alpha o antibodies had no effect on carbachol-induced Ca2+ mobilization. Microinjection of anti-G alpha i and anti-G alpha q antibodies had a minimal effect on glucose-induced Ca2+ mobilization (< 8% of cells nonresponding), but microinjection of anti-G alpha o increased the proportion of nonresponding cells to 37%. The results suggest that, in beta-TC3 cells, distinct signal transduction pathways with specific G-protein involvement may interact with secretagogue-induced Ca2+ mobilization and, ultimately, with insulin secretion.

Amino Acid Sequence↗
PubMed1993

Development and histology of fibrous architecture of the fetal temporomandibular joint.

The developmental history of the temporomandibular joint (TMJ) was investigated in 10 fetuses of 4 to 10 months of gestational age. The S-type structure of the disc is formed by the following bases: 1) the flat upper and concave lower surfaces of the disc; 2) thinner intermediate zone and thicker anterior and posterior bands; 3) the projection of the articular tuberculum and superoposterior growth of the condyle. The posterolateral part of the disc was the thickest and the corresponding part of the fossa was the deepest. The condyle was originally positioned beneath the part of disc that was considered the main force-bearing area. The distribution and arrangement of elastic and collagen fibers in the disc was proportional to disc function. Gross elastic fibers in the posterolateral part of the posterior band were connected with the upper head of the pterygoideus lateralis muscle fibers running medioanteriorly. They were indicated to be antagonistic with each other. At 4 months of gestational age, a few elastic fibers appeared in the bilaminar region and began to form bundles as the fetus grew. At full-term dense elastic fibers were found in the upper stratum of the bilaminar region.

Gestational Age↗
PubMed1993

Ability of hydroxyapatite-bone morphogenetic (corrected from morphologenetic) protein (BMP) complex to induce dentin formation in dogs.

This histological investigation examined the formation and differentiation of pulp cells under the influence of HAP/BMP complex. HAP/BMP complex was implanted in exposed pulp of the mandibular premolars and alveolar bone defect in the dog. Sequential changes in these areas were examined mainly under a light microscope and partly under a scanning electron microscope. Two weeks after the operation, fibroblast-like cells proliferated right beneath the implanted complex, and after 3 weeks, dentin including dentin tubules grew in the pulp. After four weeks a dentin bridge composed of osteoid dentin was found, and after 8 weeks this dentin calcified and covered the defective surface of the root and adhered to new bone surrounding the HAP granules. The results indicated that the dentin induced by HAP/BMP complex may be of two types: tubular dentin and osteodentin. This complex exhibited outstanding ability to induce dentinogenesis and osteogenesis.

Animals↗
PubMed1993

Phenotypic heterogeneity within clonogenic ductal cell populations isolated from normal adult rat liver.

Oval cells represent a heterogeneous population composed of ductal cells, transitional cells with characteristics of both hepatocytes and bile ductal cells, and bipotential stem cells capable of differentiation along a biliary or hepatocytic lineage. In an attempt to define markers that would distinguish between individual cell types within the oval cell population, a number of investigators have utilized hybridoma technology to produce cell type-specific monoclonal antibodies. Several of these have proved to be of value in delineating lineage relationships during fetal development and carcinogenesis in the adult liver. Most recently, monoclonal antibodies specific for OC2 and OC3, two oval cell antigens identified in our laboratory, have been used in combination with magnetic beads or a fluorescence-activated cell sorter to isolate antigenically defined subpopulations from adult and fetal rat liver. Using OC2-positive fetal liver cells as an immunogen, we have produced a monoclonal antibody identifying a bile ductal antigen, designated BD1, that is differentially expressed by oval cells and normal ductal cells. This antigen shows a heterogeneous pattern of reactivity that defines three distinct cell populations in regenerating rat liver: a BD1-negative, [3H]thymidine-labeled cell population thought to contain hepatic stem cells; a BD1-positive, thymidine-negative population of terminally differentiated ductal cells; and a BD1-positive, [3H]thymidine-positive population of mature ductal cells. Analysis of BD1 expression in vitro on continuous lines of bile duct epithelial cells (BDEC) demonstrated that BD1 was rapidly increased in late G1 and lost during G2/M. High passage cultures of BDEC and primary cultures of oval cells expressed low or undetectable levels of BD1 and high passage BDEC failed to express BD1 when arrested in late G1. Taken together, these results suggested that oval cells and high passage BDEC might share a subtle defect in cell cycle regulation marked by an inability to upregulate the expression of BD1.

Animals↗
PubMed1993

Tissue distribution of the non-polymorphic major histocompatibility complex class I-like molecule, CD1d.

The CD1 gene family is composed of five distinct molecules: CD1a, b, c, d and e. CD1a, b and c are primarily expressed thymically with limited extrathymic expression. Preliminary studies have shown that CD1d is primarily expressed extrathymically in gastrointestinal epithelial cells, renal tubular epithelial cells and B cells. This report characterizes the expression of CD1d in a variety of human tissues by immunohistochemistry using two anti-human CD1d monoclonal antibodies (mAb). CD1d was found in a wide range of tissues including the intestine, liver, pancreas, skin, kidney, uterus, conjunctiva, epididymis, thymus and tonsil. Within those tissues CD1d was mainly present in epithelial cells, vascular smooth muscle cells and parenchymal cells. Therefore, the tissue distribution of CD1d is distinct from CD1a-c and classical major histocompatibility complex (MHC) proteins implicating a unique role for CD1d in the immune system.

Antibodies, Monoclonal↗
PubMed1993

[Transformation of recombinant plasmid pRK 41 and amplification of full-length coding region of human brain myelin basic protein cDNA].

Transformation of the recombinant plasmid pRK41 containing 2.15 kd human brain myelin basic protein MBP)-coding sequence and 3' untranslated region (1.2 kb) into the E. coli JM109 was made by using Hanahan's method. Positive colonies were screened with digoxigenin oligo labelled rat brain MBP cDNA fragment (1.2 kb). To remove 3' untranslated region and obtain the full-length coding sequence of MBP cDNA, a pair of specific DNA primers was designed and synthesized. A 600 bp fragment was amplified from the recombinant plasmid, extracted from the positive colony by using polymerase chain reaction (PCR). The PCR fragment was isolated, and then digested with BamH I, Kpn I and BamH I + Kpn I. The results of restriction analysis indicate that the PCR amplified fragment is desirable and can be used directly to constract expression vectors.

Base Sequence↗
PubMed1993

[Effect of nifedipine on contractive motility and ciliary ultrastructure of rabbit fallopian tube].

The effects of nifedipine (Nif) on the motility of isolated isthmus of rabbit Fallopian tube were studied in comparison with those of verapamil (Ver) and cinnarizine (Cin). Nif (0.01 mumol.L-1), Ver (0.03 mumol.L-1), and Cin (3 mumol/L-1) inhibited the spontaneous contraction, and the contraction caused by norepinephrine (NE). The pD'2 values of Nif, Ver, and Cin were 6.86, 6.13, and 4.43, respectively. Moreover, both Nif and Ver delayed the ovum transport through the Fallopian tube 48 h after iv chorionic gonadotropin (HCG). Nif did not modify the ultrastructure of the ampulla ciliary microtubule, but it influenced the mitochondrial structure and caused an irregular ciliary motion.

Animals↗
PubMed1993

[PCR amplification of nerve growth factor (beta-NGF) gene in human brain].

Nerve growth factor, an important nutrition factor for neuronal survival, growth, development and maintenance of neuronal functions, consists of three kinds of subunit (alpha 2, beta and gamma 2), but only the subunit beta-NGF has the biological activity. beta-NGF coding sequence is located in a single exon of NGF gene. In our study, a pair of specific primers (29 mers) has been designed and synthesized with ABI 318 A DNA synthesizer. The upstream primer includes an initiation codon and the 1st to 20th base of the exon. The downstream primer includes the complementary sequence of 334 to 354 base of the exon and a stop codon. The full-length DNA fragment of beta-NGF gene has been successfully obtained from human brain cDNA library in lambda ZAPII/EcoRI and human brain genomic DNA respectively by using polymerase chain reaction. The reaction program consists of denaturing at 93 degrees C for 1 min, annealing at 55 degrees C for 1 min, and extending at 72 degrees C for 2 min. Both amplified products of 350 bp in length coincide with the exon coding sequence and are enough for the analysis of restriction mapping, DNA sequencing and construction of expression vector.

Brain↗
PubMed1993

The cloning and sequencing of coat protein gene from beet necrotic yellow vein virus.

The beet necrotic yellow vein virus (BNYVV) isolate NM was isolated from sugarbeet infected with rhizomania in Inner Mongolia of China. The cDNA of BNYVV coat protein (CP) gene was amplified from the extracted RNA of BNYVV isolate NM by using the polymerase chain reaction (PCR) and cloned into pGEM-7zf(+). Its complete nucleotide sequence was determined by means of Sanger's dideoxy-mediated chain-termination method. The result shows that CP gene of BNYVV isolate has 567 nucleotides. It shares 98.8% and 96.7% identity with the CP gene of isolate F13 (report in reference [1]) in terms of amino acid and nucleotide sequence, respectively.

Amino Acid Sequence↗
PubMed1993

[Helicobacter pylori associated gastritis: a primary study of ammonia and urea in gastric juice and mucus in gastric mucosa].

The mucosa of 46 patients with histological chronic gastritis were cultured for helicobacter pylori (HP) and the ammonia and urea in their gastric juice were also determined. The results showed the average ammonia concentration (1.22 +/- 0.23 mmol/L) in HP positive patients was higher than that of HP negative patients (0.72 +/- 0.25 mmol/L), (P < 0.05). But the average urea concentration (0.45 +/- 0.29 mmol/L) in HP positive patients was lower than that of HP negative patients (2.71 +/- 1.20 mmol/L), (P < 0.05). The higher the level of ammonia stands, the more severe the gastritis is. (rs = 0.556). On the other hand, the quantity of mucus was elevated in 18 patients among 28 patients with HP eradicated by drug treatment, which was significantly different from the patients with HP not eradicated. It is suggested that the epithelium of gastric mucosa and the mucus are the chief components of the gastric mucosa barrier; the presence of HP increases ammonia, and thus damages the gastric epithelium and reduces the quantity of mucus. Consequently, the protective gastric mucosa barrier is damaged, and then comes the liability to HP-associated gastritis.

Ammonia↗
PubMed1993

[Clinical observation of immunotherapy in ocular malignant tumors with lymphokine-activated killing (LAK) cell].

In this paper, the authors reported the method of treating ocular malignant tumors with lymphokine-activated killing cells which were induced by rIL-2 in vitro. Among the sixteen cases of ocular tumors, 4 cases of 5 base cell carcinoma (1 case of which was partially extinctive), 4 cases of tarsal gland carcinoma, 2 cases of squamous cell carcinoma and respectively 1 case of retinoblastoma, non-Hodgkin's lymphoma, intraorbital hemangiopericytoma, intraorbital fibrous histiocytomas and hidradenocarcinoma were completely extinctive. The result shows that the immunotherapy method is effective.

Adolescent↗
PubMed1993

Characterization of a mature bile duct antigen expressed on a subpopulation of biliary ductular cells but absent from oval cells.

Hybridomas were produced with immune spleen cells generated by immunization of Balb/c mice with oval cell antigen (OC.2)-positive 17-day fetal liver cells isolated on antibody-coated magnetic beads. A primary screen by indirect immunofluorescence on frozen sections of fetal and adult liver identified several hybridomas secreting antibodies reactive with bile ducts and oval cells. One of these recognized an epitope, designated BD1, which was expressed on intrahepatic bile ducts in 16-day fetal and adult rat liver and in liver from rats fed a choline-deficient diet containing ethionine and rats treated with 2-acetylaminofluorine, but was absent from morphologically defined oval cells induced by a choline-deficient diet containing ethionine or by 2-acetylaminofluorine. Double-labeling immunofluorescence analysis with monoclonal antibody BD1 and OV6, a monoclonal antibody that reacts uniformly with all bile ducts and oval cells, revealed that BD1 expression on the intrahepatic bile ductular cells of normal adult rat liver was heterogeneous with a major ductal cell population (60% to 70%) expressing high levels of BD1 and a minor ductal cell population (30% to 40%) displaying undetectable or low levels of BD1 expression. Analysis of fetal liver demonstrated the presence of BD1-positive cells at day 16 of gestation on duct-like structures in contact with portal mesenchyme, an observation suggesting that expression of BD1 was associated with commitment of hepatoblasts to a ductular lineage. Taken together, our findings suggest that oval cells may be derived from an antigenically distinct subpopulation of bile ductal cells.

2-Acetylaminofluorene↗
PubMed1993

Production of anti-tumor human monoclonal antibodies using different approaches.

The production of anti-tumor human monoclonal antibodies (MAbs) by human-human or human-mouse hybridoma technology was studied. UC729-6, a human lymphoblastoid cell line, or NS-1, a mouse myeloma cell line, were fused with lymphocytes isolated from regional lymph modes of 26 patients with breast or gastrointestinal cancer, resulting in 130 immunoglobulin-secreting human-human hybrids and 21 human-mouse hybrids. The supernatants of 88 hybrids were screened against a panel of cancer cells. The supernatants of 37 human-human hybrids and 2 human-mouse hybrids reacted with cancer cell lines. After three times subcloning, only one anti-breast cancer hybrid human MAb, IgG(lambda) human-human hybridoma (MUBL-6), and one anti-gastric cancer human MAb, IgM(lambda) human-mouse hybridoma (HMG-1), were obtained. The antibody-secreting level was 1-4 micrograms/ml/24 h. Production of anti-breast cancer human MAbs by Epstein-Barr virus (EBV) hybridoma was also studied. Human lymphocytes were derived from draining lymph nodes of a breast cancer patient, whose serum antibody strongly reacted with tumor associated antigen (TAA). The enriched B cells were transformed with EBV in vitro. Positive antibody-secreting B cells were selected, expanded, and fused with heteromyeloma SHMD-33. The fusion frequency was 28/10(7) lymphocytes. Among them were 16 hybridomas secreting human immunoglobulin. After subcloning, 60% of the cloned hybridomas kept their antibody-secreting ability. Six observed hybridomas remained stable for more than 1 year in tissue cultures. The antibody-secreting level was 2.9-30 micrograms/ml/24 h. Supernatants from these hybridomas all reacted with breast cancer cell lines but not with gastric cancer cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[A study on the effect of stimulation of amygdaloid complex on the electrical response of auditory cortex in rabbits].

Experiments were performed on 40 adult rabbits immobilized with Flaxedil. The effect of stimulation of amygdaloid complex on the click evoked potential of Woolsey's AI, AII and the auditory cortex behind the rhinal sulcus (ACBRS) was examined by single unit analysis. The results showed that stimulation of lateral nucleus and basal nucleus of amygdala could induce either a facilitory or an inhibitory effect on the evoked potential and the unit discharges. The latency of the inhibitory effect was about 10-25ms, and lasted for 20-115ms. A facilitory effect with a latency as short as 2ms was also observed in one animal. The experimental results indicate that the effect of amygdaloid complex stimulation as transmitted through polysynaptic circuit while the facilitatory effect was monosynaptic. The functional significance of the amygdaloid effect was discussed.

Acoustic Stimulation↗
PubMed1992

Molecular cloning of the alcohol/hydroxysteroid form (hSTa) of sulfotransferase from human liver.

A cDNA encoding the human alcohol/hydroxysteroid sulfotransferase (h-ST-a), which catalyzes the sulfo-conjugation of many drugs and hormones, was isolated from a human liver cDNA library using a rat STa (rSTa) cDNA probe. The cDNA, designated as hSTa, consists of 1069 base pairs (bp) and contains an 855-nucleotide open reading frame beginning at nucleotide 65, which encodes a 285 amino acid polypeptide of 33.76 kDa. A second cDNA clone (1563 bp) was truncated 5' at nucleotide 231 (lacking the first 15 amino acids) with identical coding region, however, it had a much longer 3' untranslated region (UTR). Both clones contained a short segment of poly(A)+ tail. Northern blot analysis of an adult human liver showed that there are at least 2 mature mRNA with sizes ranging from approximately 1.1 kb to 1.7 kb, verifying the authenticity of the obtained cDNA clones. From the sequence alignment, the hSTa shares 62%/74%, 39%/59%, 35%/48%, 36%/54% identity with rSTa, rSTp (phenol), rSTe (estrogen), and bovine STe (bSTe) at the deduced amino acid and DNA levels, respectively, indicating that there are at least three subfamilies (alcohol, phenol and estrogen) of genes that encode for sulfotransferases in mammals.

Amino Acid Sequence↗