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Biomedical subjects

C Zhang

Publications and source records attributed to C Zhang.

At least 631 records · Page 35Linked to original sources
PubMed1995

Clinical analysis of steroid glaucoma.

PURPOSE: The authors accumulated 15 cases (26 eyes) of steroid glaucoma due to topical administration of dexamethasone or prednisolone. METHODS: From 1970 to 1990, 26 eyes in 15 cases were observed (bilateral 11 cases, unilateral 4 cases) including 12 right eyes and 14 left eyes. 10 cases were male and 5 cases female with age ranging from 14 to 52 years averaging 28 years. 25 eyes had the manifestation of chronic open angle glaucoma in the clinical course, and 1 eye simulated an acute glaucoma attack. RESULTS: All patients had taken antiglaucoma medication before coming to our hospital, but the IOP was over 6.7 kPa in 9 eyes. The C/D ratio was equal to or over 0.6 in 9 cases (16 eyes), and the values were inconsistent between both eyes in 55% of the patients. Treatment for glaucoma was immediate discontinuation of the steroids with antiglaucoma medication if necessary. Three eyes received filtering operations and 2 eyes had the removal of subconjunctival residual steroid. Normal IOP was restored in months up to a year. CONCLUSION: Dexamethasone or prednisolone were the easiest to induce steroid glaucoma when the patients had long-term use of steroid eyedrops.

Adolescent↗
PubMed1995

Confirmation of the helical structure of the 5'/3' termini of the essential DNA packaging pRNA of phage phi 29.

Bacteriophage phi 29 is typical of double-stranded DNA viruses in that its genome is packaged into a preformed procapsid during viral assembly. An intriguing feature of phi 29 is the presence of a 120-base virus-encoded RNA (pRNA) that is indispensable for DNA packaging. Phylogenetic comparison of similar RNAs in numerous phages has revealed that the secondary structure of the pRNA is well conserved. Computer analysis predicts the presence of an extensive segment of helix with three single-base bulges generated by the pairing of the 5' and 3' ends. The desire to understand the role played by the pRNA in DNA packaging has led to a mutational analysis of the 5'-/3'-terminal region, which is believed to be important in DNA translocation. Deletion of 3 bases from the 3' end of the RNA, shortening the pRNA from 120 to 117 bases, was tolerated without loss of activity, but additional deletion of the base 117 resulted in 100-fold less activity, and a 115-base pRNA was virtually nonfunctional. Additionally, the three unpaired one-base bulges within the helical stretches of the paired proximate ends were nonessential for pRNA activity, as demonstrated by deletion of the bulge individually. An extensive series of helix disruptions by single- and multiple-base substitution almost invariably led to the loss of DNA packaging activity. Additional mutations that restored predicted base pairings rescued pRNA activity. This second site suppression confirmed that the 5'- and 3'-end region was paired and was indeed a helical stretch. The secondary structure was of greater importance than the primary sequence, with the exception of the requirement of an adenine at either the third or fourth position. The specific requirement of an adenine in phi 29 pRNA at this position, as well as conservation of this position in other phage pRNAs, implicates that this base may play a special role in either the DNA-packaging reaction or the maintenance of the pRNA tertiary structure.

Bacillus Phages↗
PubMed1995

[Evaluation of combined test of sequential fecal occult blood and albumin in the screening of colorectal neoplasms].

Fecal albumin test was developed and the combined use of sequential occult blood test and albumin test (SA) was evaluated and compared with sequential fecal occult blood test (S) in 365 cases diagnosed clinically and pathologically and in 883 asymptomatic individuals. In the former group, the sensitivity of detection of colorectal cancer was: 50.7% (37/73) with S and 87.7% (64/73) with SA (P < 0.001), and that of the adenoma was: 8.1% (6/74) with S and 36.5% (27/74) with SA (P < 0.001). In the latter group 2 of 3 cancer patients were detected with S while all with SA, and the detection rate of adenoma was: 4.7% (4/85) with S and 42.4% (36/85) with SA (P < 0.001) it is suggested that the additional use of fecal albumin test is of help in detecting precancerous inflammatory bowel lesions without bleeding.

Adenoma↗
PubMed1995

[Influence of changing Ca++ concentration in neiguan (PC 6) on the effect of acupuncture treating experimental arrhythmia of rabbits].

We have made two kinds of experimental arrhythmia of rabbits by injecting aconitine and stimulating hypothalamus. Acupuncture could improve arrhythmia, after Ca++ in Neiguan (PC6) was chelated with EDTA solution the effect of acupuncturing Neiguan (PC6) was abolished. It indicates that Ca++ may be the key factor of acupuncture effect and one of the important material bases of the functional activity of meridians and collaterals.

Aconitine↗
PubMed1995

[Clinical evaluation of force-sensitive probe in the examination of tooth sensitivity].

Two methods were tested for measuring the sensitivity of dentin to mechanical (force-sensitive probe) and cold air stimuli. Of the 212 sensitive teeth in 71 patients, 94.8% were sensitive to probe, with a mean threshold of 22.79g; 89.6% were sensitive to cold air. These two methods were significantly correlated (P < 0.001). The occlusal sites were less sensitive than the buccal sites measured by probe and cold air. It suggests that force-sensitive probe is a simple, quantitative method of measuring tooth hypersensitivity.

Adult↗
PubMed1995

The role of platelet-derived growth factor in the development of mouse molars.

Platelet-derived growth factor (PDGF) is a potent mitogen that functions in cytodifferentiation and wound healing. PDGF receptor-alpha (PDGFR-alpha) is required for the normal development of the dental ectomesenchyme (Stephenson et al., Proc. Natl. Acad. Sci. USA 88: 6-10, 1991). To investigate the regulatory potential of PDGF on tooth development, the expression of PDGF-AA was determined by reverse transcription-polymerase chain reaction (RT-PCR), the PDGF ligands and receptors were localized by immunohistochemistry. The growth-promoting effects of exogenous PDGF-AA on molar explants were determined by assaying for tritiated thymidine incorporation, the presence of type I collagen and amelogenin messenger RNA transcripts, and total DNA, RNA and protein accumulation. Based upon the temporal and spatial localization, PDGFs and their receptors are present in the enamel epithelia and pulpal mesenchyme of developing mouse molars. Exogenous PDGF-AA administration increased the total protein accumulation of mouse molar explants but produces no discernible effect on amelogenin and type I collagen expression.

Animals↗
PubMed1995

[Clinical application of MRI in ophthalmic field].

PURPOSE: To investigate the application of MRI in ocular diseases and analysis the character of MRI-s parameters in these diseases. METHODS: MRI was applied among 68 patients with neurophthalmic disorders, orbits diseases, and intraocular lensions. RESULTS: The position (location) and feature of the lesions were diagnosed with clinical analysis. CONCLUSION: MRI possesses the special value in the differentiation diagnosis of neurophthalmic disease, orbit disordes and intraocular conditions.

Adolescent↗
PubMed1994

Insulin-induced activation of glycerol-3-phosphate acyltransferase by a chiro-inositol-containing insulin mediator is defective in adipocytes of insulin-resistant, type II diabetic, Goto-Kakizaki rats.

Type II diabetic Goto-Kakizaki (GK) rats were insulin-resistant in euglycemic-hyperinsulinemic clamp studies. We therefore examined insulin signaling systems in control Wistar and diabetic GK rats. Glycerol-3-phosphate acyltransferase (G3PAT), which is activated by headgroup mediators released from glycosyl-phosphatidylinositol (GPI), was activated by insulin in intact and cell-free adipocyte preparations of control, but not diabetic, rats. A specific chiro-inositol-containing inositol phosphoglycan (IPG) mediator, prepared from beef liver, bypassed this defect and comparably activated G3PAT in cell-free adipocyte preparations of both diabetic GK and control rats. A myo-inositol-containing IPG mediator did not activate G3PAT. Relative to control adipocytes, labeling of GPI by [3H]glucosamine was diminished by 50% and insulin failed to stimulate GPI hydrolysis in GK adipocytes. In contrast to GPI-dependent G3PAT activation, insulin-stimulated hexose transport was intact in adipocytes and soleus and gastrocnemius muscles of the GK rat, as was insulin-induced activation of mitogen-activated protein kinase and protein kinase C. We conclude that (i) chiro-inositol-containing IPG mediator activates G3PAT during insulin action, (ii) diabetic GK rats have a defect in synthesizing or releasing functional chiro-inositol-containing IPG, and (iii) defective IPG-regulated intracellular glucose metabolism contributes importantly to insulin resistance in diabetic GK rats.

Adipocytes↗
PubMed1994

Focal adhesion kinase expressed by nerve cell lines shows increased tyrosine phosphorylation in response to Alzheimer's A beta peptide.

A beta is a 39-43-amino acid peptide that accumulates as extracellular aggregates in Alzheimer's disease-afflicted brain tissue. Contact between these aggregates and neurons is potentially pathogenic, although little is known about the cellular transduction mechanisms. We have investigated the impact of A beta aggregates on the neuronal control of protein tyrosine phosphorylation, which underlies signal transduction for multiple families of growth factor and adhesion receptors. Added to cultures of rat and human nerve cell lines, A beta aggregates evoked a non-desensitizing increase (1.3-3.6-fold) in tyrosine phosphorylation in a band at 118 kDa. The 118-kDa protein was determined by immunoprecipitation to be pp125FAK, not previously documented in cells of neuronal lineage. Immunoblots with anti-focal adhesion kinase (FAK) showed that A beta aggregates had no effect on FAK protein levels. The increase in FAK tyrosine phosphorylation occurred at doses of A beta aggregates that evoked lactate dehydrogenase release; evoked tyrosine phosphorylation preceded the first detectable lactate dehydrogenase release by 4 h. Like degeneration, the FAK response was dependent on A beta aggregation and neuronal differentiation. Since tyrosine phosphorylation of FAK is essential to its activity as a transduction component of integrin-, peptide-, and lysophosphatidic acid-mediated signaling, the data establish a link between A beta aggregates and signal transduction pathways implicated in diverse cell functions including neurite outgrowth, control of the cell cycle, and apoptosis.

Amino Acid Sequence↗
PubMed1994

Role of CD26/dipeptidyl peptidase IV in human immunodeficiency virus type 1 infection and apoptosis.

To examine the role of CD26/dipeptidyl peptidase IV (DPPIV; EC 3.4.14.5) in infection by human immunodeficiency virus type 1 (HIV-1), we utilized CD26 cDNA-transfected Jurkat T-cell lines. Both CD26- parental Jurkat cells and mutant CD26+ (DPPIV-) transfected Jurkat cells were readily infected with HIV-1, whereas wild-type CD26+ (DPPIV+) transfected Jurkat cells were more resistant to HIV-1 infection. Our results suggest that CD26 is not essential for HIV-1 infectivity as suggested by others but that DPPIV enzyme activity may decrease the efficiency of HIV-1 infection. Of great interest, we found that mutant CD26+ (DPPIV-) transfectants and CD26- parental Jurkat cells strongly expressed CD95 (Fas/Apo-1) and were more sensitive than wild-type CD26+ (DPPIV+) transfectants to the induction of apoptosis by anti-CD95 monoclonal antibody. These results suggest that CD26 may play a role in HIV-1-associated loss of -CD4+ cells through the process of programmed cell death.

Antigens, CD↗
PubMed1994

ADP-ribosylation factor (ARF)-like 3, a new member of the ARF family of GTP-binding proteins cloned from human and rat tissues.

The human and rat homologues of a new member of the ADP-ribosylation factor (ARF) family of 21-kDa GTP-binding proteins, termed Arl3, were identified as an expressed sequence tag (human) and as a product of polymerase chain reaction amplification using degenerate probes derived from conserved sequences in members of the ARF family (rat). Alignments of the full-length open reading frames of the human and rat homologues revealed the encoded proteins to be over 97% identical to each other and 43% identical to human ARF1. Northern blots of mRNA from seven human tissues and four rat tissues revealed the presence of a ubiquitous band of about 1 kilobase in length that hybridized with the corresponding Arl3 probes. A number of human tumor cell lines expressed Arl3, as determined by immunoblotting with an Arl-specific antibody, raised against a peptide derived from the human Arl3 sequence. The level of Arl3 expressed in these cell lines was on the order of 0.01% of total cell protein. Purified recombinant human Arl3 was shown to bind guanine nucleotides but lacks ARF activity and intrinsic or ARF GTPase-activating protein-stimulated GTPase activity. In contrast to ARF proteins, the Arl3 protein has reduced dependence on phospholipids and magnesium for guanine nucleotide exchange. Thus, Arl3 is a ubiquitously expressed GTP-binding protein in the ARF family with distinctive biochemical properties consistent with its having unique, but unknown, role(s) in cell physiology.

ADP-Ribosylation Factor 1↗
PubMed1994

The proximate 5' and 3' ends of the 120-base viral RNA (pRNA) are crucial for the packaging of bacteriophage phi 29 DNA.

In vitro mutagenesis was performed to identify the DNA packaging domain of the 120-base pRNA essential and specific for DNA encapsidation by bacteriophage phi 29 of Bacillus subtilis. All deletions and mutations targeted the 5' and 3' ends of the pRNA. DNA templates of a control or mutant pRNAs used for in vitro transcription with T7 RNA polymerase were generated by PCR. Fourteen mutant pRNA molecules were synthesized from DNA templates either directly after PCR or after cloning the PCR fragments into the pCR II vector. Ten of the mutant pRNA species were inactive in packaging of the phi 29 genome. Mutation of base one at the 5' end did not affect the pRNA packaging activity. Mutation of the first two bases at the 5' end of the pRNA to noncomplementary bases in the predicted RNA secondary structure (U1 C2/A117G116 to G1 G2/A117G116) resulted in a pRNA with no detectable DNA-gp3 packaging activity assayed by either sucrose gradient sedimentation or agarose gel electrophoresis, and 10(5)-fold reduction in activity was found when measured by plaque-forming units with a new highly sensitive assay system. Changing bases 116 and 117 so that they were complementary to the mutated bases, 1 and 2, from the previous mutant (G1 G2/A117G116 to G1 G2/C117C116) generated an RNA molecule with restored DNA packaging ability. Our results show that, although not essential for procapsid binding, both the 5' and 3' ends of the pRNA were proximate and crucial for phi 29 DNA packaging.

Bacillus Phages↗
PubMed1994

Molecular cloning and sequencing of porcine somatostatin receptor 2.

The porcine somatostatin receptor gene was isolated from a porcine genomic library. Based on the deduced amino acid sequence, this gene encodes a 369 amino acid protein with seven hydrophobic segments, a characteristic of G-protein coupled receptors, and shows only 13 amino acid difference (identity 96.5%, similarity 99.2%) in amino acid sequence from human somatostatin receptor 2. The data indicate that the amino acid sequence is highly conserved in pig, human, rat and mouse somatostatin receptor 2.

Amino Acid Sequence↗