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Biomedical subjects

Q Zhou

Publications and source records attributed to Q Zhou.

At least 163 records · Page 9Linked to original sources
PubMed2000

[Changes of blood vessels in glucocorticoid-induced avascular necrosis of femoral head in rabbits].

OBJECTIVE: To evaluate the effects of fatty tamponade in medullary cavity (serious intramedullary fatty infiltration) on the changes of blood vessels in femoral heads during the pathological process of glucocorticoid (GC)-induced avascular necrosis (AVM) of the femoral heads. METHODS: The animal model of AVN was established with injection of dexamethasone (DEX) at a high dose of 2.5 mg x kg(-1) x d(-1) in rabbits. Histopathological and morphological changes of blood vessels in the femoral heads were investigated during GC-treatment and after the cessation scanning electron microscope, light microscope, and image analysis. RESULTS: At the 2nd week of DEX-treatment, the fatty tamponade in the medullary cavity appeared in the femoral heads. Intramedullary vascular sinusoids were pressed by an excess of lipocytes and became narrow. The impressions of lipocytes on the surface of vascular sinusoids were definitely displayed on the vascular casts and ink-perfused slides of the femoral heads. These changes were pronounced with the prolongation of the treatment and the vascular sinusoids gradually lost their characteristics. Image analysis showed that the vascular area in the femoral heads continuously decreased. At the 8th week, the effects of fatty tamponade were the most marked. Intramedullary vessels became very sparse and the vascular area decreased to 1/4 of the controls. At the 6th week after the GC-treatment cessation, intramedullary fatty infiltration still existed. The blood vessels were fine and sparse, and the structural features of vascular sinusoids disappeared in the load-bearing regions of the femoral heads. At the 4th week, typical osteonecrosis focuses appeared in the femoral heads. The focuses became larger and the degree of osteonecrosis was increasing with the time of experiment. CONCLUSION: The fatty tamponade in the medullary cavity is one of the important pathological factors causing ischemic damage to the femoral heads, and plays an important role in the early stage of GC-induced AVN.

Animals↗
PubMed2000

[Study of the distribution feature of the endocrine cells of human islet and its relation to microvasculature].

Double immunohistochemical stain was used for the study of distribution feature of the endocrine cells of human islets and its relation to the microvasculature. The results were as follows (1) Sheath islet was found in human adult islets and the B cells situated the central part of the islets and arrounding it were the A and D cells which formed the sheath of the islets. (2) The identical distribution of the A and D cells was found. (3) Some islets were divided into several "subunite" by connective tissue in which the B cells and A(or D) cells situated the central and peripheral part respectively. (4) The A and D cells were near the microvasculature. These results will provide morphologic basis for the research of the functional relation among the endocrine cells.

Humans↗
PubMed2000

[The analysis of linseed oil by FTIR and FT-Raman].

Linseed oil is an important natural sanitarian oil. To qualitative analyses the linseed oil, FTIR and FT-Raman were used to identify the contents of it. It is indicated that each component has characteristic frequency, and can be discriminated from others by IR and Raman spectroscopy. This is useful for the further on-line quantitative analysis and quality control of linseed oil.

Fourier Analysis↗
PubMed2000

[Study on thermal unfolding process of trichosanthin by FTIR spectroscopy].

Fourier-transform infared spectroscopy, combined with resolution-enhancement techniques including second-derivative spectroscopy, Fourier self-deconvolution and curvefitting technique, was used to investigate the thermally induced unfolding process of anti-HIV-I toxin protein trichosanthin. During heating from 25 degrees C to 85 degrees C, the peak of Amide I shifted to 1618 cm-1 while the secondary structural contents change with the temperature. Upon cooling the protein from 85 degrees C to 25 degrees C, the contour of the Amide I do not change. All these show that the thermal unfolding of trichosanthin is an irreversible intermolecular aggregation process between 25 degrees C and 85 degrees C. The changes of secondary structures with temperature suggest the presence of folding intermediates.

Hot Temperature↗
PubMed2000

[Quantitative analysis of rutin and vitamin C by NIR FTIR].

In this paper, near-infrared diffuse reflectance spectroscopy(NIRDRS) method was used as a quantitative tool to measure the solid mixture of rutin and vitamin C by collecting NIR spectra in the range 7,000-3,900 cm-1. The quantitative mathematics model was established with partial least squares(PLS) method. The correlation coefficient was 99.75%, the standard error of Rutin was 0.363%, and the standard error of Vitamin C was 1.078%. The methods are rapid, exact and nondestructive to samples. The components of the samples can be individually analyzed with high accuracy and precision, so NIRDRS can be a useful method of quality control of pharmaceuticals in the future.

Ascorbic Acid↗
PubMed2000

[Study on unfolding process of neo-trichosanthin in the presence of GdnHCl].

Fluorescence spectroscopy and circular dichroism are effective instruments to determine the chemical unfolding process of protein solution. In this paper, both of them were selected to investigate the unfolding processes of neo-trichosanthin in the presence of GdnHCl. One GdnHCl is added, both spectra of fluorescence and circular dichroism changed remarkedly. The denaturation curve of CD ellipticity meets that of fluorescence intensive excitation at 295 nm very well. The result shows that, in the presence of GdnHCl, the unfolding of neo-trichosantin matches the two-state process well. The model is different from the model of trichosanthin that others reported previously. The mechanism will be further probed later.

Circular Dichroism↗
PubMed2000

[Study on mechanism of different PHAs during heating by FTIR].

In this paper, PHB, P(HO-co-HD), a various composition of P(HB-co-HV) copolymer and P(HB-co-HH) copolymer were studied both at normal temperature and in the process of increasing and decreasing temperature using FTIR spectroscopy technology. Results showed that FTIR spectra of PHAs with various compositions have distinguishing characteristics. Physical transformation occurred when PHAs were treated with heat denaturalization, and this physical process was reversible.

Bacteria↗
PubMed2000

[Determination of eight trace elements in kadsura coccinea by flame atomic absorption spectrophotometry].

In this paper, we used the flame atomic absorption spectrophotometry to determine the contents of Zn, Fe, Ca, Cu, K, Na, Mn, Mg in the kadsura coccinea. We assayed the determination conditions systematically. The SrCl2 was sued to eliminate coexisting elements. And we achieved the purpose that we can determine a lot of elements in the same liquor at the same time. It shows that this method is simple, convenient and accurate.

Calcium↗
PubMed2000

[Real time monitor of rutin stability during heating by Fourier transform infrared spectroscopy].

The thermal stability of the natural product of rutin was studied by Fourier Transform Infrared Spectroscopy (FTIR) in this paper for the first time. To monitor the changing of rutin in real time, the temperature-control accessory was also used to in-situ follow the thermal behavior. It is demonstrated that as the temperature increased from 25 degrees C to 270 degrees C, the thermally-induced denaturation of rutin was accompanied by the oxidation and thermal discomposed procedure. The structure of rutin changed at a lower temperature (75 degrees C). This is not only indicating the existence of an intermediate state, but also approved that the stability of rutin is poor. While at the higher temperature (270 degrees C), rutin discomposed into two results. It is proved that this method is fast, accurate and having no solvent effect. Samples can thus be examined undestroyed.

Computer Systems↗
PubMed2000

[The latest development of the research on Chinese medicine by molecular vibrational spectroscopy].

The latest development of the molecular vibrational spectroscopy (Fourier Transform Raman Spectroscopy and Fourier Transform Infraed Spectroscopy) and the latest application of the non-destructive identification, quantitative analysis, thermal-stability monitoring and Chinese medicine optimizing were described in this paper. Some Chinese crude herbs can be directly and quickly identified by Fourier Transform Raman spectroscopy (FT - Raman) and Diffused Reflection Fourier Transform Infrared Spectroscopy (DR-FTIR). The content of Chinese herbs, medicine and medicament can be quantified without destruction by Diffused Reflection Fourier Transform and Near Infrared Spectroscopy (DR-NIR-FTIR). The mechanism of interaction between the Chinese medicine and some cells or bacteria can be in situ monitored by FT-Raman and HATR-FTIR. Best medicine could be selected and medicament could be optimized according to the injury degree of the cell or bacteria. The decomposing and degenerating process of medicines can also be timely monitored by FT-Raman and the temperature controlled FTIR. These are the latest use of molecular spectroscopy in Chinese medicine. The fast indentification, quantitative analysis monitoring, thermal stability predicting and the optimizing of Chinese herbs, medicine and medicament can be guided by the above mentioned methods. It is proved that these methods are nondestructive to samples, fast accurate, and easy to use.

Drug Stability↗
PubMed1999

Non-invasive transgenic mouse genotyping using stool analysis.

Commonly applied genotyping of transgenic mice involves using tail or ear biopsies which may cause discomfort to the animal. We tested the possibility of polymerase chain reaction (PCR)-based mouse genotyping using stool specimens from three transgenic mouse lines that overexpress 10-18 transgene copies of human keratin polypeptide 18, as compared to genotyping using tail biopsies. Stool specimens were obtained with ease and provided easy detection of the human transgene product. The method was also able to detect endogenous mouse actin and keratin genes which presumably are present at two copies each. Nested PCR was not necessary for genotyping using stool-derived genomic material but did increase the relative magnitude of the signal obtained. The non-invasive genotyping method described herein offers a reproducible, sensitive and effective modality that could replace invasive tissue sampling procedures currently used to test thousands of genetically altered mice.

Animals↗
PubMed1999

Acquired antagonistic activity of a bispecific diabody directed against two different epitopes on vascular endothelial growth factor receptor 2.

Bispecific antibody (BsAb) technology has been successfully used as a means to construct novel antibody (Ab) molecules with increased avidity for binding, by combining two Ab or their fragments directed against different epitopes within the same antigen. Using two single chain antibodies (scFv) isolated from a phage display library, we have constructed a bispecific diabody directed against two different epitopes on the extracellular domain (ECD) of human vascular endothelial growth factor receptor 2 (VEGFR2), the kinase-insert domain-containing receptor (KDR). Neither of the parent scFv blocks KDR/VEGF interactions or inhibits VEGF-induced receptor activation. The diabody binds to KDR with an affinity that is 1.5- to 3-fold higher than its parent scFv, mainly due to a much slower dissociation rate (k(off)), which is approximately 17- to 26-fold slower than that of the individual scFv. In addition, the diabody binds simultaneously to, and thus cross-links, the two epitopes on the receptor(s). It is rather unexpected that the diabody effectively blocked KDR/VEGF interactions, and inhibited both VEGF-induced activation of the receptor and mitogenesis of human endothelial cells. Taken together, our results suggest that the diabody is most likely to exert its effect through steric hindrance and/or causing major conformational changes of the receptor. This is the first report on the construction of a bispecific diabody with acquired novel antagonistic activity.

Antibodies, Bispecific↗
PubMed1999

Negative feedback regulation of TGF-beta signaling by the SnoN oncoprotein.

Smad proteins mediate transforming growth factor-beta (TGF-beta) signaling to regulate cell growth and differentiation. The SnoN oncoprotein was found to interact with Smad2 and Smad4 and to repress their abilities to activate transcription through recruitment of the transcriptional corepressor N-CoR. Immediately after TGF-beta stimulation, SnoN is rapidly degraded by the nuclear accumulation of Smad3, allowing the activation of TGF-beta target genes. By 2 hours, TGF-beta induces a marked increase in SnoN expression, resulting in termination of Smad-mediated transactivation. Thus, SnoN maintains the repressed state of TGF-beta-responsive genes in the absence of ligand and participates in negative feedback regulation of TGF-beta signaling.

Cell Division↗
PubMed1999

Persistent Fos protein expression after orofacial deep or cutaneous tissue inflammation in rats: implications for persistent orofacial pain.

This study was designed to systematically examine the effects of persistent orofacial tissue injury on prolonged neuronal activation in the trigeminal nociceptive pathways by directly comparing the effects of orofacial deep vs. cutaneous tissue inflammation on brainstem Fos protein expression, a marker of neuronal activation. Complete Freund's adjuvant (CFA) was injected unilaterally into the rat temporomandibular joint (TMJ) or perioral (PO) skin to produce inflammation in deep or cutaneous tissues, respectively. Rats were perfused 2 hours, 24 hours, 3 days, or 10 days following CFA injection. The TMJ and PO inflammation-induced Fos expression paralleled the intensity and course of inflammation over the 10-day observation period, suggesting that the increase in intensities and persistence of Fos protein expression may be associated with a maintained increase in peripheral input. Compared to PO CFA injection, the injection of CFA into the TMJ produced a significantly stronger inflammation associated with a greater Fos expression. In TMJ- but not in PO-inflamed rats, Fos-like immunoreactivity (LI) spread from superficial to deep upper cervical dorsal horn as the inflammation persisted and there was a dominant ipsilateral Fos-labeling in the paratrigeminal nucleus. Common to TMJ and PO inflammation, Fos-LI was induced in the trigeminal subnuclei interpolaris and caudalis, C1-2 dorsal horn, and other medullary nuclei. Substantial bilateral Fos-LI was found in the interpolaris-caudalis trigeminal transition zone. Further analysis revealed that Fos-LI in the ventral transition zone was equivalent bilaterally, whereas Fos-LI in the dorsal transition zone was predominantly ipsilateral to the inflammation. The differential induction of Fos expression suggests that an increase in TMJ C-fiber input after inflammation and robust central neuronal hyperexcitability contribute to persistent pain associated with temporomandibular disorders.

Animals↗
PubMed1999

The Ski oncoprotein interacts with the Smad proteins to repress TGFbeta signaling.

Smad proteins are critical signal transducers downstream of the receptors of the transforming growth factor-beta (TGFbeta) superfamily. On phosphorylation and activation by the active TGFbeta receptor complex, Smad2 and Smad3 form hetero-oligomers with Smad4 and translocate into the nucleus, where they interact with different cellular partners, bind to DNA, regulate transcription of various downstream response genes, and cross-talk with other signaling pathways. Here we show that a nuclear oncoprotein, Ski, can interact directly with Smad2, Smad3, and Smad4 on a TGFbeta-responsive promoter element and repress their abilities to activate transcription through recruitment of the nuclear transcriptional corepressor N-CoR and possibly its associated histone deacetylase complex. Overexpression of Ski in a TGFbeta-responsive cell line renders it resistant to TGFbeta-induced growth inhibition and defective in activation of JunB expression. This ability to overcome TGFbeta-induced growth arrest may be responsible for the transforming activity of Ski in human and avian cancer cells. Our studies suggest a new paradigm for inactivation of the Smad proteins by an oncoprotein through transcriptional repression.

Cell Line↗
PubMed1999

Cypher, a striated muscle-restricted PDZ and LIM domain-containing protein, binds to alpha-actinin-2 and protein kinase C.

We have cloned and characterized a novel striated muscle-restricted protein (Cypher) that has two mRNA splice variants, designated Cypher1 and Cypher2. Both proteins contain an amino-terminal PDZ domain. Cypher1, but not Cypher2, contains three carboxyl-terminal LIM domains and an amino acid repeat sequence that exhibits homology to a repeat sequence found in the largest subunit of RNA polymerase II. cypher1 and cypher2 mRNAs exhibited identical expression patterns. Both are exclusively expressed in cardiac and striated muscle in embryonic and adult stages. By biochemical assays, we have demonstrated that Cypher1 and Cypher2 bind to alpha-actinin-2 via their PDZ domains. This interaction has been further confirmed by immunohistochemical studies that demonstrated co-localization of Cypher and alpha-actinin at the Z-lines of cardiac muscle. We have also found that Cypher1 binds to protein kinase C through its LIM domains. Phosphorylation of Cypher by protein kinase C has demonstrated the functional significance of this interaction. Together, our data suggest that Cypher1 may function as an adaptor in striated muscle to couple protein kinase C-mediated signaling, via its LIM domains, to the cytoskeleton (alpha-actinin-2) through its PDZ domain.

Actinin↗
PubMed1999

Specific interaction of Tat with the human but not rodent P-TEFb complex mediates the species-specific Tat activation of HIV-1 transcription.

Tat stimulation of HIV-1 transcriptional elongation is species-specific and is believed to require a specific cellular cofactor present in many human and primate cells but not in nonpermissive rodent cells. Human P-TEFb, composed of Cdk9 and cyclin T1, is a general transcription elongation factor that phosphorylates the C-terminal domain of RNA polymerase II. Previous studies have also implicated P-TEFb as a Tat-specific cellular cofactor and, in particular, human cyclin T1 as responsible for the species-specific Tat activation. To obtain functional evidence in support of these hypotheses, we generated and examined the activities of human-rodent "hybrid" P-TEFb complexes. We found that P-TEFb complexes containing human cyclin T1 complexed with either human or rodent Cdk9 supported Tat transactivation and interacted with the Tat activation domain and the HIV-1 TAR RNA element to form TAR loop-dependent ribonucleoprotein complexes. Although a stable complex containing rodent cyclin T1 and human Cdk9 was capable of phosphorylating CTD and mediating basal HIV-1 elongation, it failed to interact with Tat and to mediate Tat transactivation, indicating that the abilities of P-TEFb to support basal elongation and Tat activation can be separated. Together, our data indicated that the specific interaction of human P-TEFb with Tat/TAR, mostly through cyclin T1, is crucial for P-TEFb to mediate a Tat-specific and species-restricted activation of HIV-1 transcription. Amino acid residues unique to human Cdk9 also contributed partially to the formation of the P-TEFb-Tat-TAR complex. Moreover, the cyclin box of cyclin T1 and its immediate flanking region are largely responsible for the specific P-TEFb-Tat interaction.

Animals↗