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Biomedical subjects

F Yang

Publications and source records attributed to F Yang.

At least 307 records · Page 17Linked to original sources
PubMed1995

A human (3.3 kb) haptoglobin-CAT transgene is modulated in lungs of transgenic mice by inflammation.

Four independent lines of transgenic mice were produced carrying integrated copies of a chimeric gene composed of 3.3 kb of the human haptoglobin 5' regulatory region fused to the CAT (chloramphenicol acetyl transferase) reporter gene. Although the endogenous mouse haptoglobin (Hp) and human haptoglobin (HP) genes express mainly in liver and lung, expression of the human 3.3-kb HP-CAT transgene was not detected until after induction of inflammation and then only in lungs. The results indicated that the transgene maintained the regulatory DNA elements required for lung specific responsiveness to inflammation in vivo but lacked the DNA sequence required for robust expression in liver. The DNA sequence(s) responsible for the normally high level of HP expression in liver either reside outside the 3.3-kb regulatory region of the HP chimeric gene or this region contains a suppressor sequence affecting tissue specific expression in the liver.

Animals↗
PubMed1995

A comparative study of karyotypes of muntjacs by chromosome painting.

We have used a combination of chromosome sorting, degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR), chromosome painting and digital image capturing and processing techniques for comparative chromosome analysis of members of the genus Muntiacus. Chromosome-specific "paints" from a female Indian muntjac were hybridised to the metaphase chromosomes of the Gongshan, Black, and Chinese muntjac by both single and three colour chromosome painting. Karyotypes and idiograms for the Indian, Gongshan, Black and Chinese muntjac were constructed, based on enhanced 4', 6-diamidino-2-phenylindole (DAPI) banding patterns. The hybridisation signal for each paint was assigned to specific bands or chromosomes for all of the above muntjac species. The interspecific chromosomal homology was demonstrated by the use of both enhanced DAPI banding and comparative chromosome painting. These results provide direct molecular cytogenetic evidence for the tandem fusion theory of the chromosome evolution of muntjac species.

Animals↗
PubMed1995

Dynamic extraction of visual evoked potentials through spatial analysis and dipole localization.

The dynamic extraction of evoked potential is a problem of great interest in EEG signal processing. In this paper, a comprehensive method is presented which integrates spatial analysis and dipole localization to make full use of the spatial-temporal information contained in the multichannel stimulation records. A realistic double boundary head model is constructed through CT scans and a two-step method devised to overcome the ill-posed nature of the forward problem of EEG caused by the low conductivity of the skull. As a result, visual evoked potentials can be effectively extracted from only two consecutive records and the dynamic information of visual evoked potential thus procured. The efficiency of the presented method has been verified by means of computer simulation and a clinical experiment.

Computer Simulation↗
PubMed1995

Nitrogen regulation of nasA and the nasB operon, which encode genes required for nitrate assimilation in Bacillus subtilis.

The divergently transcribed nasA gene and nasB operon are required for nitrate and nitrite assimilation in Bacillus subtilis. The beta-galactosidase activity of transcriptional lacZ fusions from the nasA and nasB promoters was high when cells were grown in minimal glucose medium containing poor nitrogen sources such as nitrate, proline, or glutamate. The expression was very low when ammonium or glutamine was used as the sole nitrogen source. The repression of the genes during growth on good sources of nitrogen required wild-type glutamine synthetase (GlnA), but not GlnR, the repressor of the glnRA operon. Primer extension analysis showed that the -10 region of each promoter resembles those of sigma A-recognized promoters. Between the divergently oriented nasA and nasB promoters is a region of dyad symmetry. Mutational analysis led to the conclusion that this sequence is required in cis for the activation of both nasA and nasB. The derepression of these genes in a glnA mutant also required this sequence. These results suggest that an unidentified transcriptional activator and glutamine synthetase function in the regulation of nasA and the nasB operon.

Bacillus subtilis↗
PubMed1995

Estimation of dynamic chemoresponsiveness in wakefulness and non-rapid-eye-movement sleep.

We developed a method for quantifying dynamic chemoresponsiveness on the basis of the ventilatory response to pseudorandom binary CO2 stimulation. The dynamic chemoreflex gain (GD) and effective time delay (TDeff) relating breath-to-breath fluctuations in alveolar PCO2 to ventilation were evaluated at frequencies between 0 and 0.05 Hz. Application of the method to simulated "data" showed that estimation errors in GD and TDeff were most likely to be minimized in the range of 0.01-0.03 Hz, corresponding to periodicities of 30-100 s. Estimation of TDeff was generally more susceptible to error than that of GD because of the limited time resolution of the breath-by-breath measurements. In eight awake normal adults, we compared estimates of GD derived from the pseudorandom binary CO2 stimulation test with peripheral and central hypercapnic sensitivities deduced from single-breath and Read rebreathing measurements in the same subject. GD at 0.02 Hz was highly correlated with peripheral hypercapnic sensitivity but poorly correlated with central hypercapnic sensitivity, underscoring the importance of the peripheral chemoreflexes in mediating ventilatory responses to phasic stimuli. Application of the procedure to a different group of 10 healthy volunteers during wakefulness and stage 2 sleep showed decreases in GD in 8 subjects but increases in 2 subjects. However, for the group as a whole, GD and TDeff did not change significantly between wakefulness and sleep. The proposed method may provide information more pertinent to periodic breathing than traditional CO2 response tests do, since the chemoreflex responses to phasic variations in blood gases are likely to be important in determining ventilatory control during sleep.

Adult↗
PubMed1995

SP-A deficiency in primate model of bronchopulmonary dysplasia with infection. In situ mRNA and immunostains.

The surfactant protein secretory cells in airway and alveolar epithelium were studied in premature baboons with bronchopulmonary dysplasia and superimposed infection. PRN animals were delivered by hysterotomy at 140 d gestational age and ventilated on clinically appropriate oxygen for a 16-d experimental period. To assess 0 time and sacrifice time gestational parameters, 140 and 156 d were studied. BPD animals were delivered at 140 d and ventilated with positive-pressure ventilation and an FIO2 of 1.0 for 11 d followed by 5 d of oxygen sufficient to maintain PAO2 at 40 to 50 mm Hg. BPD-infected animals were comparably ventilated and treated like the BPD group except that 10(8) E. coli organisms were endotracheally instilled on Day 11. In situ hybridization studies for mRNA expression of SP-A, SP-B, and SP-C revealed that an SP-A mRNA deficiency, present at 140 d, persisted in the BPD and BPD-infected groups, whereas SP-A mRNA was abundant in PRN and 156 d gestation control groups. SP-B and SP-C mRNA expression in the two hyperoxically injured groups was particularly extensive in cells around peribronchiolar and perivasicular sites. Immunostaining with SP-A, SP-B, and SP-C antibodies showed variable staining patterns. The study clearly demonstrates that a deficiency of SP-A mRNA expression persists in chronic lung injury and that variable protein staining patterns are manifested depending upon the underlying pathology.

Animals↗
PubMed1995

Cell type-specific and inflammatory-induced expression of haptoglobin gene in lung.

BACKGROUND: Haptoglobin (HP) is a hemoglobin-binding protein and a major acute phase reactant. Recently, HP has been shown to possess antioxidant and angiogenic properties. HP is known to be produced mainly in the liver. Expression of HP in specific cells of nonhepatic origin including lung cells has not been studied before. The presence of extracellular plasma proteins in lung epithelial fluid has been assumed to be of blood serum origin. EXPERIMENTAL DESIGN: To investigate the expression of the HP gene in lung, the presence of HP mRNA and the production of HP protein in the lung were examined by Northern blot analysis and immunoprecipitation, respectively. Cellular expression of HP during development and inflammation were studied by in situ hybridization with lung tissues derived from different gestational stages from baboons and mice and from mice treated with lipopolysaccharide. RESULTS: Northern blot and in situ hybridization analyses established a high level of expression of HP in fetal and adult lung tissues, which were confined to the epithelial lining of the airways in mouse and baboon. After inflammation had been induced in vivo, expression of the HP gene rose fourfold in lung, an increase compatible with that observed in normal mouse liver. However, HP mRNA level was not significantly altered in airway epithelium. Instead, HP expression in alveolar epithelial cells, most likely type 2 cells, was strongly increased. CONCLUSIONS: Our data suggest that locally synthesized HP provides a major source of antioxidant and/or antimicrobial activity in the mucus blanket as well as in the alveolar fluid in the lung. The regulation and cell type-specific expression of HP during development and inflammation indicate a protective role for HP in lung and confirm recent reports that HP plays important roles in protecting against infection and in repairing injured tissues.

Animals↗
PubMed1995

Transmembrane Ca2+ gradient-mediated phosphatidylcholine modulating sarcoplasmic reticulum C(a2+)-ATPase.

The sarcoplasmic reticulum (SR) C(a2+)-ATPase was purified and reconstituted into the sealed phospholipids vesicles with or without transmembrane Ca2+ gradient. The role of phospholipids, especially phosphatidylcholine (PC), in the modulation of C(a2+)-ATPase by transmembrane Ca2+ gradient was investigated. The results are as follows. (i) Incubated with phospholipids, the enzyme activity of the delipidated C(a2+)-ATPase is inhibited by Ca2+ and the highest inhibition is observed in the presence of PC. (ii) When there exists a transmembrane Ca2+ gradient (higher Ca2+ concentration inside vesicles, 1,000 mumol/L:50 mumol/L, similar to the physiological condition), the inhibition of C(a2+)-ATPase by transmembrane Ca2+ gradient can be only observed in the vesicles containing PC:PE, but not in those containing PS:PE or PG:PE. The highest inhibition is obtained at a 50:50 molar ratio of PC:PE (iii) By comparing the effects of PC differing in acyl chains, higher inhibition of C(a2+)-ATPase is observed in vesicles containing DPPC:PE and DOPC:PE, while no inhibition in DMPC:PE vesicles (iv) If the transmembrane Ca2+ gradient is in the inverse direction, the enzyme activity of C(a2+)-ATPase is inhibited whenever reconstituted with acidic or neutral phospholipids.

Animals↗
PubMed1995

[Sequencing of polyhedrin gene of Leucania separata multiple capsid nuclear polyhedrosis virus by silver sequencing system].

The genome of LsNPV was digested with EcoRV and cloned into pBluescript. With the partial polyhedrin gene of Autographa californica as a probe, positive recombinants were screened by colony in situ hybridization, further characterized by sequencing, and designated as pLsEV and pLsPH5. The intact 741 bp polyhedrin gene of LsNPV is located on the two recombinants revealed by Silver Sequencing System, and shares 80.0% and 97.0% nucleotide identity of the coding sequence, 87.8% and 97.5% amino acid identity with AcMNPV and MbMNPV respectively. Glu is the richest amino acid, and Gln and Trp the poorest amino acid in the polyhedrin of LsNPV. The codons ended with pyrimidine were higher in the codon usage. There was a signal-peptide-like hydrophobic region of 26 amino acids in the N end of polyhedrin.

Amino Acid Sequence↗
PubMed1995

[nm23 gene product/NDPK expression and its clinical significance in human colorectal carcinoma].

The expression of nm23 gene product/NDPK was examined immunohistochemically in resected human colorectal carcinomas using anti-NDPK polyclonal antibody. Of the 103 carcinomas tested, 76.7% (79 cases) showed positive staining of nm23/NDPK in the primary lesions. In patients without regional lymph node metastasis, the positive staining rate (90.5%, 38/42) was significantly higher than that in those with nodal involvement (67.2%, 41/61). Inverse relationships were found between nm23/NDPK expression and tumor invasion or the progression of Dukes' staging. Expression of NDPK was positively associated with longer post-operative survival and the relationship was significant. Therefore, our data indicated that nm23 gene plays an important role in lymph node metastasis and invasion in colorectal carcinomas. The expression of nm23 gene product/NDPK may be a useful tool for prognosis of human colorectal carcinomas.

Adenocarcinoma↗
PubMed1995

Membrane formation on the surface of implanted posterior chamber intraocular lenses.

PURPOSE: To study the prevention and treatment of the membrane formation on the lens surface after extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens (PCIOL) implantation. METHODS: We reviewed the records of 312 cataractous patients that had undergone ECCE with PCIOL implantation between 1989 and 1993. Postoperatively all patients were examined under slit-lamp microscopy. The membrane formation on the surface of PCIOL in pupilar area was divided into four grades. Two membranes of surgical removal were observed under a transmission electron microscopy. One PCIOL of surgical removal was observed under a scanning electron microscopy. RESULTS: Of 312 patients, 21 had the membrane formation on the surface of the PCIOL postoperatively. The incidence of the membrane formation was 6.7%. Comparisons with cases of senile cataract showed the incidence to be significantly the highest among: 1. patients who had traumatic cataract (P < 0.05); 2. patients with complicated cataract (P < 0.05). Intraoperatively residual lens cortex and rupture of posterior capsule, interval time between the first and second eye operations less than 1 month are the main factors of membrane formation. The ultrastructure in membrane and cytology on the lens surface showed that the membrane on the surface of PCIOLs is usually composed of a cellular protein film and cellular elements, including macrophages, fibroblast-like cells, epithelioid cells, giant cells, fibroblasts and collagen fibrils, etc. CONCLUSIONS: The cellular response on the surface of an implanted PCIOL is a chronic foreign-body inflammatory reaction and the membrane of the surface of implanted PCIOL is a reactive membrane of the foreign-body.

Eye↗
PubMed1995

[Expression of P53 protein in laryngeal carcinoma and its clinical significance].

Using the monoclonal antibody DO-7, the expressions of P53 protein in 38 cases of laryngeal squamous cell carcinoma (LSCC), and 29 cases of laryngeal benign neoplasms (LBN) were studied immunohistochemically. The results showed that: (1) 25 of 38 (66%) LSCCs, but only 2 of 29 (7%) LBNs showed expression of mutant-type P53 protein. The high rate of P53 protein expression was related to the occurrence of laryngeal carcinoma, and is valuable in diagnosis and differential diagnosis of laryngeal carcinoma; (2) in some LSCCs, the mutant-type P53 protein was also expressed in dysplastic epithelium near the cancer tissues. These epithelial cells near the tumor in which P53 gene has been altered, probably are the source or portent of tumor recurrence; (3) the five year survival rate of mutant-type P53 protein negative LSCC patients was higher than that of positive LSCC patients. The expression of mutant-type P53 protein might be related to LSCC prognosis.

Adult↗
PubMed1994

Polyclonals to beta-amyloid(1-42) identify most plaque and vascular deposits in Alzheimer cortex, but not striatum.

Alzheimer's beta-peptides (A beta) aggregation rates depend on A beta length. We made synthetic peptide antisera to A beta 34-40 and 37-42. Purified anti-34-40 preferentially recognizes beta 1-40, vascular amyloid and a subset of plaques while purified anti-37-42 recognizes A beta 1-42 and not A beta 1-40 in dot and Western blots and immunoprecipitates; 37-42 precipitates a small percentage of fibroblast secreted A beta and strongly stains all deposits identified by monoclonals to A beta on adjacent sections from frontal cortex, but not in dorsal striatum.

Alzheimer Disease↗
PubMed1994

Latent transforming growth factor-beta is produced by chondrocytes and activated by extracellular matrix vesicles upon exposure to 1,25-(OH)2D3.

Resting zone and growth zone (GC) costochondral chondrocytes constitutively release latent, but not active, transforming growth factor-beta (TGF-beta) into the culture medium. When exogenous TGF-beta is added to the culture medium, no autocrine effect is observed. However, when 1,25-(OH)2D3 is added, a dose-dependent inhibition of latent TGF-beta release is found. Messenger RNA levels for TGF-beta 1 are unchanged by treatment with either 1,25-(OH)2D3 or TGF-beta 1. Since active growth factor was not observed in the conditioned medium, we tested the hypothesis that latent TGF-beta could be activated in the matrix. GC matrix vesicles, extracellular organelles associated with matrix calcification, were able to activate latent TGF-beta 1 and TGF-beta 2 when preincubated with 1,25-(OH)2D3. In contrast, GC plasma membranes activated latent TGF-beta, and addition of 1,25-(OH)2D3 inhibited this activation. The 1,25-(OH)2D3-dependent decrease in latent TGF-beta in the medium, with no detectable change in mRNA level, and the inhibition of plasma membrane activation of latent TGF-beta by 1,25-(OH)2D3 suggest that 1,25-(OH)2D3 may act through post-transcriptional and/or nongenomic mechanisms. The results also suggest that latent TGF-beta is activated in the matrix and that 1,25-(OH)2D3 regulates this activation by a direct, nongenomic action on the matrix vesicle membrane.

24,25-Dihydroxyvitamin D 3↗
PubMed1994

Monoclonal antibody to the C-terminus of beta-amyloid.

Soluble amyloid beta-protein (A beta) is normally produced, but forms deposits in the brain of Alzheimer's (AD) patients. The length of isolated A beta in SDS-insoluble amyloid from AD brain is reported to vary between plaques and vessels ranging from 28 to 43, with major species being 40 and 42 residues. Because the A beta C-terminus determines aggregation rates, we made an A beta monoclonal antibody distinguishing beta 1-42 from beta 1-40. In AD cortex, the beta 1-42 antibody recognizes all the structures identified by monoclonal to beta 1-40 on adjacent sections: plaque cores, diffuse A beta deposits and vascular amyloid. These antibodies help define variation in A beta length between different deposits, regions and autopsied brains.

Alzheimer Disease↗