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Biomedical subjects

Q Zhu

Publications and source records attributed to Q Zhu.

At least 253 records · Page 14Linked to original sources
PubMed1994

Experimental studies of the inhibitory effects of green tea catechin on mice large intestinal cancers induced by 1,2-dimethylhydrazine.

Three hundred Kunming mice were randomly divided into six groups (half males and half females in each group). Group 1 was the positive control group, Groups 2, 3, 4 and 5 were experimental groups and Group 6 was used as the solvent control group. Mice in Groups 1-4 were injected with 1,2-dimethylhydrazine (1,2-DMH) (20 mg/kg body wt.) solution subcutaneously once a week from the 2nd week to the 20th week. From the 1st week to the 23rd week, mice in Groups 2, 3 and 4 were given catechin (1 mg/mouse), catechin (2 mg/mouse) and EGCG (2 mg/mouse), respectively, five times a week. Mice in Group 5 received only catechin (3 mg/mouse) five times a week from the 1st to the 23rd week. Mice in Group 6 were injected with an equal volume of 1 mmol EDTA solution subcutaneously once a week from the 2nd to the 20th week. At the end of the 27th week, all the mice were killed by cervical dislocation (Zhu, Q.H. and Zhu, Q.F. (1991) Laboratory Animal Science, 1st edition. The Junior Educational Publisher, Guangdong). Pathological examinations indicated that the incidence of large intestinal cancers occurring in Group 1 was 80%, significantly higher than that in Groups 2, 3 and 4 (p < 0.001). No tumors were found in Groups 5 and 6. This might suggest that green tea has preventive effects on large intestinal cancer induction in spite of the different doses of catechin. Immunohistochemistry studies showed that green tea catechins could enhance the activity of superoxide dismutase (SOD) in tissues.

1,2-Dimethylhydrazine↗
PubMed1994

Antifreeze glycoproteins from antarctic notothenioid fishes fail to protect the rat cardiac explant during hypothermic and freezing preservation.

The antarctic notothenioid fishes avoid freezing through the action of circulating antifreeze glycoproteins (AFGPs). This study investigated whether AFGPs could serve as cryoprotectants for the isolated rat heart under three different storage conditions. (1) Hearts were flushed with 15 mg AFGP/ml cardioplegic solution (CP) and stored for 9 h at 0 degrees C. This AFGP concentration has been reported to protect pig oocytes during hypothermic storage. (2) Hearts were flushed with 10 mg AFGP/ml CP-14 and stored frozen at -1.4 degrees C for 3 h. At this concentration the AFGPs significantly reduce the solution freezing point and also change the crystal morphology from dendritic to spicular. (3) Hearts were flushed with 10 micrograms AFGP/ml CP-15 and stored frozen at -1.4 degrees C for 5 h. At this low concentration the AFGPs have a strong inhibitory effect on ice recrystallization, but have little effect on the freezing point and less apparent effect on the crystal habit. After hypothermic or freezing storage, the functional viability was assessed by determining cardiac output (CO) during working reperfusion. No difference in CO was found between AFGP-treated and untreated hearts after 9 h of 0 degree C storage. CO in hearts frozen in CP-14 without AFGPs recovered to 50% of the freshly perfused control hearts. Hearts frozen in the presence of high concentrations of AFGPs (10 mg/ml CP-14) failed to beat upon thawing and reperfusion, although their tissue ice content was less than that found in hearts without AFGP treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Isolation of a monocot 3-hydroxy-3-methylglutaryl coenzyme A reductase gene that is elicitor-inducible.

The rice (Oryza sativa) phytoalexins, momilactones and oryzalexins, are synthesized by the isoprenoid pathway. An early step in this pathway, one that is rate-limiting in mammalian systems, is catalyzed by the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR). A gene that encodes this enzyme has been isolated from rice, and found to contain an open reading frame of 1527 bases. The encoded protein sequence of the rice HMGR appears to be conserved with respect to other HMGR proteins, and 1 or 2 membrane-spanning domains characteristic of plant HMGRs are predicted by a hydropathy plot of the amino acid sequence. The protein is truncated at its 5' end, and shows reduced sequence conservation in this region as compared to other plant sequences. The rice genome contains a small family of HMGR genes. The isolated gene, HMGR I, is expressed at low levels in both vegetative and floral organs of rice plants. It is not induced in plants by wounding, but is strongly and rapidly induced in suspension cells by a fungal cell wall elicitor from the pathogen Magnaporthe grisea, causal agent of rice blast disease. This suggests that HMGR I may be important in the induction of rice phytoalexin biosynthesis in response to pathogen attack, and therefore may play a key role as a component of the inducible defense mechanism in rice.

Amino Acid Sequence↗
PubMed1994

Synergistic activation of DNA synthesis in astrocytes by fibroblast growth factors and extracellular ATP.

The effects of extracellular ATP and polypeptide growth factors on DNA synthesis in primary cultures of rat astrocytes have been examined. It was found that ATP acts synergistically with either acidic or basic fibroblast growth factor to stimulate DNA synthesis. The specificity of this effect was demonstrated by the inability of ATP to potentiate DNA synthesis induced by platelet-derived growth factor or epidermal growth factor. ATP appears to act via P2 purinergic receptors, because (a) it was more effective than adenosine and (b) the synergistic effect was observed with the hydrolysis-resistant P2 agonists, ADP beta S and ATP gamma S. The evidence suggests that extracellular ATP may be an important factor in regulating the extent of gliosis and, as such, may be involved in mechanisms of neural injury and repair.

Adenosine↗
PubMed1994

Destabilization of glial fibrillary acidic protein mRNA in astrocytes by ammonia and protection by extracellular ATP.

The expression of the astrocyte-specific intermediate filament protein, glial fibrillary acidic protein (GFAP), is decreased in hepatic encephalopathy and increased in numerous neurological conditions including brain injury. However, little is known about the molecular mechanisms that regulate GFAP expression. Here it is reported that treatment of cultured astrocytes with ammonium chloride reduces GFAP mRNA by up to 85% without inhibiting total RNA synthesis. The effect of NH4Cl was time and dose dependent. The reduction in GFAP mRNA was detected 3 h after initiation of ammonia treatment with a maximum effect observed at 24 h. Significant decreases in GFAP mRNA were observed at 2, 5, and 10 mM NH4Cl. Concurrent treatment with extracellular ATP prevented the loss of GFAP mRNA, possibly by activation of purinergic receptors. In addition, removal of ammonium chloride restored GFAP mRNA to normal levels. Nuclear runoff experiments indicated that NH4Cl did not inhibit GFAP mRNA transcription. Studies using alpha-amanitin, an inhibitor of RNA polymerase II, showed that NH4Cl decreased the stability of GFAP mRNA by approximately 50%. This destabilization of GFAP mRNA may be an important factor in the pathogenesis of hepatic encephalopathy. Because increased GFAP is an important component of reactive gliosis, understanding the mechanisms that destabilize GFAP mRNA may facilitate strategies to minimize the gliosis associated with brain injury.

Adenosine Triphosphate↗
PubMed1994

Adenosine deaminase inhibitor in cardioplegia enhanced function preservation of the hypothermically stored rat heart.

Adenosine (ADO) has been shown to be protective to the ischemic-reperfused myocardium. This study tested the hypothesis that inhibition of myocardial adenosine deaminase during cold storage will elevate tissue ADO content, improve the cardiac function, and preserve ATP. The isolated rat hearts (6-9 hearts/group) were flushed with a cardioplegic solution containing 0-75 microM erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and immersion-stored at 0 degree C for 9 hr. Function was assessed after 30 min working reperfusion. Function of the unstored hearts (n = 11, mean +/- SE) including heart rate (293 +/- 13 bpm), aortic flow (AF; 52.5 +/- 1.1 ml/min), coronary flow (CF; 23.5 +/- 1.3 ml/min), cardiac output (CO; 76.0 +/- 2.1 ml/min), systolic pressure (SP; 136 +/- 2 mmHg), diastolic pressure (DP; 63 +/- 1 mm Hg), work (90.5 +/- 3.4 g-m/min), and coronary vascular resistance (CVR; 2.77 +/- 0.14 mmHg-min/ml) served as controls. Heart rate in all stored hearts returned to normal after reperfusion. Recovery of other function in no-EHNA group was: AF, 52 +/- 7; CF, 55 +/- 5; CO, 53 +/- 6; SP, 79 +/- 4; DP, 93 +/- 3; work, 47 +/- 7; and CVR, 171 +/- 15% of control. EHNA improved functional recovery in a dose-dependent fashion. At the optimal concentration of 25 microM, the recovery was: AF, 83 +/- 6; CF, 68 +/- 4; CO, 78 +/- 5; SP, 90 +/- 3; DP, 105 +/- 5; work, 77 +/- 8; and CVR 151 +/- 9% of control. ADO A1 receptor antagonists, 8-phenyltheophylline (1 microM) and 1,3-dipropyl-8-cyclopentylxanthine (0.1 microM) blocked the effects of 25 microM EHNA; the recovery of CO was reduced to 65 +/- 3 and 50 +/- 2% of the control, respectively. Tissue ADO content in 25 microM EHNA hearts at the end of storage was 95 +/- 19 nmol/g dry wt, which was significantly elevated from 15 +/- 3 nmol/g dry wt in no-EHNA hearts. EHNA also caused a 45-fold increase in the release of ADO over no-EHNA group during the first 10 min of reperfusion. But EHNA treatment did not cause any change in either end-storage or end-reperfusion myocardial ATP levels. Thus EHNA in cardioplegic solution inhibited cardiac ADO catabolism during long-term hypothermic storage and improved function preservation partially via an ADO A1 receptor-mediated mechanism without invoking ATP conservation.

Adenine↗
PubMed1994

Wavefront amplitude distribution in the female breast.

Ultrasound measurements of a large population of wavefronts transmitted through female breasts at 3 and 4 MHz show that the wavefront amplitude distribution is close to Rayleigh. This finding is consistent with a fully developed scatter field, implying that the scatter energy removed from the coherent incident beam dominates the wavefront. The wavefront received from an inhomogeneous medium is the superposition of an incident wave plus a scattered wave. If the scattered field is weak, the received field is dominated by the incident field and the wavefront amplitude distribution is Rician. If the scattered field is strong, the received field is primarily the scattered field and the wavefront amplitude distribution is Rayleigh. If, in addition to scattering, refraction between bodies of different refractive indexes occurs, the total net effect on the wavefront amplitude distribution is the same as for strong scattering. This is what we have observed in the highly refractive female breast. This result has implications for the design of high lateral-resolution echo scanners that will incorporate adaptive phase deaberration algorithms. The published algorithms were developed for weak scattering and therefore may not be powerful enough. Alternatives have to be found to deaberrate the severe wavefront distortion in the breast.

Breast↗
PubMed1994

One exon of the human LSF gene includes conserved regions involved in novel DNA-binding and dimerization motifs.

The transcription factor LSF, identified as a HeLa protein that binds the simian virus 40 late promoter, recognizes direct repeats with a center-to-center spacing of 10 bp. The characterization of two human cDNAs, representing alternatively spliced mRNAs, provides insight into the unusual DNA-binding and oligomerization properties of LSF. The sequence of the full-length LSF is identical to that of the transcription factors alpha CP2 and LBP-1c and has similarity to the Drosophila transcription factor Elf-1/NTF-1. Using an epitope-counting method, we show that LSF binds DNA as a homodimer. LSF-ID, which is identical to LBP-1d, contains an in-frame internal deletion of 51 amino acids resulting from alternative mRNA splicing. Unlike LSF, LSF-ID did not bind LSF DNA-binding sites. Furthermore, LSF-ID did not affect the binding of LSF to DNA, suggesting that the two proteins do not interact. Of three short regions with a high degree of homology between LSF and Elf-1/NTF-1, LSF-ID lacks two, which are predicted to form beta-strands. Double amino acid substitutions in each of these regions eliminated specific DNA-binding activity, similarly to the LSF-ID deletion. The dimerization potential of these mutants was measured both by the ability to inhibit the binding of LSF to DNA and by direct protein-protein interaction studies. Mutations in one homology region, but not the other, functionally eliminated dimerization.

Alternative Splicing↗
PubMed1994

Efficacy of cefazolin in promoting ovine tracheal epithelial repair.

Inhalation of toxic materials has been shown injurious to the upper airways. Because secondary infection can slow the repair process, we undertook this study to determine the efficacy of antibiotic therapy in promoting the healing process of acute tracheal wounds. In 18 anesthetized sheep, a portion of the cervical trachea was exposed to smoke from smoldering cotton cooled to 38 degrees C. Nine received the broad-spectrum antibiotic, cefazolin, while none received saline placebo. At 13 days after injury, nonciliated and ciliated cell counts were 75% and 33% respectively of noninjured trachea receiving placebo, while in those receiving cefazolin, nonciliated and ciliated cell counts increased to 93% and 114% of paired noninjured trachea, respectively. We suggest that cefazolin therapy allows cell proliferation and differentiation to proceed more rapidly than observed with placebo therapy and thus may be a helpful augmentor to the healing of an acute airway injury.

Animals↗
PubMed1994

[The effects of nucleus central lateralis on the unit discharges in posterior group of thalamic nuclei evoked by splanchnic afferents in cats].

The effects of the nucleus central lateralis (CL) on the unit discharges evoked by the splanchnic afferents in the posterior group of thalamic nuclei (PO) were studied with extracellular microelectrode techniques. In 35 cate, 96 units (98%) producing evoked discharges in PO with the latency range of 30-150ms were observed. The evoked discharges of 69 units in PO were depressed by stimulating CL with a short train of electric pulse through a bipolar electrode, but the other 27 units were uninfluenced. The inhibition of CL can be classified into 3 forms: the instant inhibition, the delayed inhibition and the continued inhibition. The injection of picrotoxin (1%, 40 microliters) into lateral ventricles of the brain could invert the inhibitory effects of PO cells caused by stimulating CL. The results suggest that there may be direct nervous pathway from CL to PO and some of these neurons may function with GABA as neurotransmitter. The CL may execute the instant inhibition through the nervous pathway. It is concluded that CL has inhibitory effect on visceral pain and GABA is involved in the inhibitory process.

Animals↗
PubMed1994

Differential ultrasonic diagnoses of pulmonary benign and malignant space-occupied lesions of the peripheral type.

87 patients with pulmonary space-occupied lesions of the peripheral type which were either adhesive or close to pleura were examined using ultrasonography. Of them, 64 cases of lung cancers and 23 of benign lesions were then confirmed by histopathology. Five sonographic features, including configuration, echogenicity patterns, bronchial air phase in foci, margin, and pleural involvement, were significantly different between malignant and benign diseases (P < 0.01). The differential ultrasonography used in this series showed a sensitivity of 61% (14/23), a specificity of 95% (61/64), and an accuracy of 86% (75/87). The results of the study demonstrate that the ultrasonography is helpful in differentiating malignant and benign peripheral lung lesions near the plerua.

Adenocarcinoma↗
PubMed1994

Transcutaneous ultrasound of the cervical esophagus in patients with esophageal carcinoma.

Transcutaneous ultrasound of the cervical esophagus was performed in 46 patients with esophageal carcinoma and in 35 controls. The former had 24 upper segmental lesions and 22 lower segmental lesions. The level of the sternoclavicular joint was used to divide the esophagus into the upper segmental (USE) and lower segmental esophagus (LSE). The anterior esophageal wall thickness and luminal dimensions were measured before and immediately after phonation. The mean wall thickness in the controls was 1.8 mm before phonation and 2.1 mm after phonation, with a significant difference (t test, P < 0.05). The mean wall thickness in the USE carcinoma group was 4.3 mm and 4.4 mm before and after phonation respectively. There was a significant difference between the controls and USE carcinoma groups (t test, P < 0.05). The cross sectional area, which was calculated as the product of anterio-posterior and lateral diameters, averaged 28 mm2 before phonation in the controls and increased to 44 mm2 after phonation (t test, P < 0.05). The mean cross sectional area in the USE carcinoma group was significantly smaller before phonation than that in the controls (t test, P < 0.05) and showed little change after phonation. No significant difference was found between LSE carcinoma and control groups. Transcutaneous ultrasound appears to be a promising non-invasive method of investigation for cervical esophageal carcinoma.

Adult↗
PubMed1994

Measurement by confocal laser scanning microscopy of the volume of epidermal nuclei in thick skin sections.

The mean volume and shape of nuclei assessed in standard tissue sections by means of stereologic and morphometric methods are associated with prognosis in tumors of different sites. Thus, accurate quantification of the volume and shape of cell nuclei can be important for cancer patients and also may be useful for a better understanding of basic cellular events, such as growth and differentiation. Confocal laser scan microscopy (CLSM) makes it possible to obtain image sets consisting of very thin serial optical slices from thick tissue sections. These images can be used with digital image processing to construct a three-dimensional (3-D) model of individual nuclei. We used CLSM to study a 50-micron-thick paraffin section of a skin biopsy. Image processing was applied to the CLSM images to precisely segment epidermal nuclei from the background, and serial two-dimensional (2-D) binary images were created. Alignment of the 2-D images that form the 3-D model of the original nuclei was carefully controlled. The series of 2-D binary images was connected with an algorithm to form the 3-D model of each complete nucleus and organized for the 3-D visualization and analysis using a 3-D volume rendering method. In this way we measured the volume and surface area of 22 intact epidermal nuclei. The mean nuclear volume was 174.7 micron3, the standard deviation of the volume 26.47 micron3, the mean surface area 168.0 micron2 and the standard deviation of the surface area 22.00 micron2.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Nucleus↗