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Biomedical subjects

Z Luo

Publications and source records attributed to Z Luo.

At least 181 records · Page 10Linked to original sources
PubMed1994

[Study on pathogenic mechanism of hemifacial spasm].

In 17 cats, areas of focal injury were induced in the facial nerve root near the brain stem by implantation of V-clamp and catgut suture. The electrophysiological examinations were made at 3 weeks after the surgery. When the mandibular branch of the facial nerve was electrically stimulated, a combined activity potential and a delayed activity could be recorded from the orbicular ocular branch of the facial nerve. The delayed activity disappeared after the motornucleu of the facial nerve was blocked with injection of 2% Lidocaine(1.5 microliter). These phenomena suggests that the artifacial synapses have been formed among the demyelinating facial nerve. The antidromic impulse of the mandibular branch of the facial nerve spread to adjacent fibers through the artifacial synapses in REZ of the facial nerve and causes the synkinases and spasm. Delayed activity may be caused by neurons of the motornucleu. Experimental lesion was also examined histologically at 3 weeks following implantation. Injured nerve showed areas of demyelination and Waller's degeneration of adjacent axons. The Nissle substances at the neurons of the motornucleu were dissolved and disappeared.

Action Potentials↗
PubMed1994

[Biological study on prognosis of laryngeal carcinoma with regional metastatic lymph nodes].

The purpose of this study is to find out the biological feature of laryngeal cancer and metastatic lymph nodes with DNA Image Analysis, Argyrophilic Nucleolar Organizer Region (AgNOR), Carcinoembryonic Antigen (EA) and Estrogen Receptor (ER) 30 patients were included in this study. It was found that carcinomatous tissues showed a statistically significantly higher DNA content, AgNOR content, and positive reaction of CEA and ER than those of normal tissue (P < 0.01). Paired comparisons were performed in primary tumor and metastases and didn't show statistical difference (P > 0.05). The group with survival time over 5 years had a significantly lower DNA content, AgNOR content, CEA positive reaction of metastases and higher ER positive reaction of metastases than those with less than 5 years survival (P < 0.01). But there no was consistant relationship between primary tumor CEA or ER positive reaction and survival time (P > 0.05). The patients who accepted radiotheraphy had better prognosis than those who didn't (P < 0.05). The above results indicate that the combined analysis of metastases and primary tumor will provide a good feature for biological activity. In addition, radiotherapy before and after operation will be beneficial.

Carcinoembryonic Antigen↗
PubMed1994

[Effects of zuzhongping on ischemic volume in the rat model of middle cerebral artery occlusion].

Using the middle cerebral artery occlusion model, we studied the effects of Zuzhongping on experimental focal cerebral ischemia. Twenty-eight adult male Wistar rats were randomly divided into three groups: (1) Zuzhongping group (n = 9), (2) Saline control group (n = 10), and (3) Blank control group (n = 9). Group 1 and group 2 received via a gastric tube 1 1ml/kg/day of Zuzhongping and normal saline, respectively. The cerebral middle arteries on the right side of 28 rats were occluded with a bipolar electro-coagulater at sites 1-2 mm from the right olfactory nerve tract. Ischemic volumes were measured by an image analytic system when the cerebral ischemia had lasted 24 h. The results showed that the ischemic volume of Zuzhongping group was significantly smaller than that of group 2 and group 3, suggesting a protective effect of Zuzhongping.

Animals↗
PubMed1993

Steel factor and granulocyte-macrophage colony stimulating factor act together to enhance choline-lipid turnover during synergistically stimulated proliferation of the human factor dependent cell line, M07E.

The hematopoietic growth factors granulocyte-macrophage colony stimulating factor and steel factor have been shown to synergize in the stimulation of proliferation of the human factor-dependent cell line M07e. We investigated the possible involvement of lpid-mediated signaling in granulocyte-macrophage colony stimulating factor and steel factor induced proliferative synergism. It was found that treatment of M07e cells with these factors alone stimulates choline lipid metabolism and that they cooperate to further enhance this effect. Therefore a choline lipid signal transduction pathway may operate as part of the series of events leading to synergistic growth induced by the combination of granulocyte-macrophage colony stimulating factor and steel factor.

Cell Division↗
PubMed1993

Phosphorylation of the regulatory subunit of type II beta cAMP-dependent protein kinase by cyclin B/p34cdc2 kinase impairs its binding to microtubule-associated protein 2.

Subcellular localization of type II cAMP-dependent protein kinase is determined by the interactions of the regulatory subunit (RII) with specific RII-anchoring proteins. By using truncated NH2-terminal RII beta fusion proteins expressed in Escherichia coli and the mitotic protein kinase p34cdc2 isolated from HeLa cells or starfish oocytes, we investigated the in vitro phosphorylation of RII beta by these kinases. The putative site for phosphorylation by the mitotic kinases is Thr-69 in the NH2-terminal domain of RII beta. This phosphorylation site matches the consensus sequence X(T/S)PX(K/R) for p34cdc2 recognition and belongs to a well-conserved sequence found in all RII beta sequences known to date. In contrast to phosphorylation by casein kinase II or the cAMP-dependent protein kinase catalytic subunit, phosphorylation of RII beta by mitotic kinases impaired its interaction with a well-known RII-anchoring protein, the neuronal microtubule-associated protein 2. The potential regulatory significance of the phosphorylation of this site on the interaction with microtubule-associated protein 2 and other RII-anchoring proteins and the physiological relevance of this cyclin B/p34cdc2 kinase-catalyzed modification of RII beta (or phosphorylation by other proline-directed protein kinases) are discussed.

Adenosine Triphosphate↗
PubMed1993

Sequestration and secretion of insulin-like growth factor-I by bovine aortic endothelial cells.

Endothelial cells elaborate growth promoting activities in culture medium that support limited smooth muscle cell and fibroblast growth in vitro in the absence of serum. We investigated whether insulin-like growth factor-I (IGF-I) was synthesized and secreted by bovine aortic endothelial cells in vitro. Subconfluent endothelial cell cultures in serum-free medium secreted severalfold higher IGF-I levels than confluent cultures by acid-sizing chromatography and IGF-I radioimmunoassay. The IGF-I secretory level was not sustained during a second serum-free incubation. In contrast, secretion of IGF binding proteins persisted and was maintained at constant levels throughout the same observation periods. Analysis of poly(A+)RNA by northern blots revealed hybridization of an IGF-I cDNA to a 7.5- to 7.0-kb transcript and superinduction of the 7.5-7.0-kb mRNA by the translational inhibitor, cyclohexamide. However, no endogenously labeled IGF-I was detected in conditioned media after incubation of cultures with [35S]cysteine or [3H]leucine. When cultures were incubated in the presence of serum supplemented with IGF-I, subconfluent cultures sequestered and released more IGF-I than confluent cultures. We concluded that the majority of IGF-I secreted in vitro was sequestered from serum.

Animals↗
PubMed1993

Basic fibroblast growth factor and transforming growth factor beta-1: synergistic mediators of angiogenesis in vitro.

We investigated the relative roles of basic fibroblast growth factor (bFGF) and transforming growth factor beta-1 (TGF-b) on bovine aortic endothelial cell mitogenesis and morphogenesis using two-dimensional Petri dish cultures and a three-dimensional hydrated collagen gel. bFGF alone stimulated endothelial cell proliferation with an EC50 of 0.5 ng/ml. At bFGF levels greater than 2.5 ng/ml, morphologic alterations in confluent monolayers predominated; cells changed from a cobblestone morphology to an elongated cell pattern and showed enhanced migration into a denuded area of a Petri dish. In the three-dimensional model, exposure of endothelial cell monolayers to high bFGF levels stimulated minor cell migration directly under the monolayer but no invasion into the gel matrix. In combination with bFGF, heparin potentiated morphogenic changes, but not mitogenesis. bFGF modification of the antiproliferative effect of TGF-b in confluent cultures was evidenced by induction of endothelial cell sprouting in response to 0.5 ng/ml TGF-b and 10-20 ng/ml bFGF in two-dimensional cultures. On collagen gels, endothelial cells migrated into the deep layers of the gel in a dose-dependent manner: invasion was maximal at 0.3-0.7 ng/ml TGF-b with decreased invasion at higher concentrations. The optimal collagen concentration that supported cell invasion was 0.075% collagen with the number of invading cells decreasing with increasing collagen gel density. By scanning electron microscopy, invading endothelial cells assumed a fibroblast-like appearance with slender cell extensions. We concluded that bFGF and TGF-b had independent effects on endothelial cell morphology and mitogenesis in culture. In combination at specific doses, these agents stimulated sprouting in the two-dimensional model and cell invasion in a collagen gel model. Morphogenic changes may be the primary event in determining angiogenesis.

Animals↗
PubMed1993

Filament overlap affects TnC extraction from skinned muscle fibres.

Recent studies on calcium regulation of muscle contraction selectively extract troponin C (TnC) from skinned skeletal muscle fibres with a low ionic strength rigor solution containing a Ca2+/Mg2+ chelator. As previous results from this laboratory and others demonstrate a crossbridge effect, especially rigor, on many of the properties of TnC, the effects of filament overlap on TnC extraction from skinned rabbit psoas muscle fibres were investigated. Tension-pCa relationships at a sarcomere length of 2.7 microns were determined before and after a 5 min TnC extraction at sarcomere lengths of 2.3, 2.5, 2.7, 3.1, 3.3 or 3.5 microns with 20 mM Tris, pH 7.8, 5 mM EDTA. The decrease in the post-extraction maximum Ca2+ activated tension, an indicator of the amount of TnC extracted, was linearly related to the overlap of the thick and thin filaments with decreases in tension being associated with a decrease in filament overlap. The smaller fibre diameter at the longer sarcomere length could facilitate diffusion of TnC from fibre segments. However, the wide range of measured diameters, 40-120 microns, accounted for only 14% of the observed tension decrement and shrinking the fibre with polyvinylpyrrolidone did not increase the tension decrement. Increasing the sarcomere length before extraction was also found to decrease the TnC content of fibre segments along with the post-extraction maximum tension. Thus, TnC appears to be preferentially extracted from non-overlap than overlap regions of the sarcomere. These results further indicate that rigor crossbridges affect TnC other than through increased Ca2+ binding and that under the conditions used here, they retard its extraction.

Animals↗
PubMed1993

Enhanced secretion of endothelin by endothelial cells in response to hemoglobin.

Confluent cultures of bovine aortic endothelium in serum-free medium were exposed to increasing concentrations (10(-6)-10(-4) M) of freshly prepared erythrocyte lysates (primarily hemoglobin). Hemoglobin increased endothelin-1 secretion into the medium in a dose-dependent manner after 24 hours. The enhanced secretion of endothelin-1 in response to hemoglobin was sustained for 72 hours, suggesting active production and secretion of endothelin-1 rather than release from intracellular pools. Secreted endothelin-1 in the medium was characterized by high-performance liquid chromatography coupled with radioimmunoassay. Endothelin-1, a potent and long-lasting vasoconstrictor, may be one of the causative factors of cerebral vasospasm after subarachnoid hemorrhage. Oxyhemoglobin, derived from periarterial clot, may play an important role in the secretion of endothelin-1 in cerebral vasospasm.

Animals↗
PubMed1993

[Memory function of patients with cerebral arteriosclerosis evaluated by Rivermead behavioural memory test].

Using Rivermead behavioural memory test, we examined 142 patients with cerebral arteriosclerosis. The results showed that the rate of anomalies of screening score in patients with cerebral arteriosclerosis were significantly higher than that of the control group (P < 0.01). The patients and control scores were significantly different (P < 0.05) in all items except the picture and face recognition. Comparing the screening score with brain CT scan, we found a relationship between brain damage and behavioural memory declination. Also, many persons of control group got low scores with behavioural memory test, suggesting that the Rivermead behavioural memory test be sensitive to memory declination. With its simplicity and sensitivity the Rivermead behavioural memory test may have some practical value in China.

Aged↗
PubMed1992

Characterization of a minimal promoter element required for transcription of the mouse type II beta regulatory subunit (RII beta) of cAMP-dependent protein kinase.

The 5'-flanking DNA of the mouse RII beta subunit of the cAMP-dependent protein kinase gene was characterized by transient transfection of RII beta-CAT constructs into mouse neuroblastoma cells (NB2a) and Chinese hamster ovary (CHO) cells and by gel mobility shift and footprinting assays. The minimal promoter of the RII beta gene was composed of two adjacent functional elements. A 3'-element which supported enhanced CAT activity was located between base pairs (bp) -267/-168 from the translation initiation start site. CAT plasmids containing these RII beta sequences showed 12- and 16-fold increased CAT activity in the NB2a and CHO cells, respectively, compared to the basic CAT vector. Plasmids containing 20 additional bp 5' to the -267/-168 fragment showed 2-fold more CAT activity than the shorter fragment in NB2a cells, while CAT activity in CHO cells was nearly the same for both constructs. CAT plasmids containing only this 20-bp fragment showed 9- and 13-fold increased CAT activity in NB2a and CHO cells, respectively. The core promoter of the RII beta gene lacked classical TATA and CAT sequences, but contained 3 copies of the Sp1 core consensus sequence. Gel mobility shift assays using 32P-labeled 5'-flanking DNA containing bp -291/-49 and nuclear extracts from NB2a and CHO cells displayed several retarded bands in the gels suggesting complex formation with nuclear DNA-binding factors. Unlabeled DNA containing bp -291/-49 blocked the appearance of all retarded bands. Competition using an oligonucleotide corresponding to the Sp1 DNA-binding site effectively blocked the appearance of the two more slowly migrating bands but did not affect the major rapidly migrating bands. DNase I footprinting analysis using purified Sp1 protein confirmed that Sp1 could bind to the Sp1 sites. Methylation interference and mutational analysis showed that one of the faster migrating bands was the result of factor binding to the DNA sequence adjacent to the Sp1 sites. Additional tissue-specific nuclear-binding factor sequences were detected upstream of the core promoter. Our data suggest that the core promoter of the RII beta gene can initiate transcription from the DNA around the Sp1 sites but that there are tissue-specific nuclear factor-binding sites located distal to the Sp1 sites.

Animals↗
PubMed1992

[Study of quantitative diagnosis of cerebral arteriosclerosis].

On the basis of clinical diagnostic criterion of cerebral arteriosclerosis, we selected, 72 patients with cerebral arteriosclerosis, 72 patients with suspected cerebral arteriosclerosis and 70 healthy individuals and screened 42 variables obtained from clinical and accessory examination with a stepwise discriminant analysis and a stepwise regression analysis. Finally we performed a logistic discriminant analysis of 15 selected variables in order to establish diagnostic discriminant formulas, Ya and Yc. It was found that a diagnostic coincidence rate for rediscriminant analysis of 212 individuals with the formulas was 100%. Very high sensitivity (96.7%), specificity (100%), positive predicted value (100%), negative predicted value (83.3%) and accuracy (97.1%) were noted in a prospective double-blind test on 34 subjects. The authors suggest that the discriminant formulas Ya and Yc established for diagnosis of cerebral arteriosclerosis be widely applicated.

Aged↗
PubMed1991

[Effect of HFMC injection of various concentrations on patency of vas deferens and resumption of fertility in rats].

Great efforts have been made to develop non-occlusive or non-ever-lasting-occlusive contraception devices in vas deferens during the recent decade at home and abroad. In our previous studies both in vivo and in vitro, polymer HFMC was found to have a spermicidal effect. In this investigation in SD rats, the relationship between the concentration of HFMC injected into the vas deferens and the resumption of fertility was studied by means of continual observations on the existence of sperms in vaginal smears from the caged female and on pup-birth delaying, so as to determine occlusion of the vas lumen and the effect of HFMC on contraception in male. The histopathological changes in the vas deferens and caudal epididymis of the HFMC-injected male rats were also observed. The results indicated: (1) HFMC in concentration over 7.5% could show temporary contraception effect by its slow releasing of H+; (2) HFMC could induce definite contraception effect which lasted longer as the concentration of HFMC given increased; (3) HFMC had no effect on the descendents in number, mortality, sex ratio, body weight and appearance; (4) the bilateral internal reproductive structures were identified normal after resumption of fertility, but 20% HFMC induced vas deferens occlusion and spermatoceles; (5) moderate concentration of HFMC was considered favorable for reversible intra-vas deferens contraception.

Animals↗
PubMed1991

[A study on autoimmune response against spermatozoa following intravas deferens injection of high molecular hydrogel HFMC in rabbits].

To investigate whether intravas injection of HFMC can result in antisperm antibodies, we divided 30 fertile male rabbits into the DMSO, 10% HFMC and 20% HFMC groups. Two to 8 months after intravas injection of the agents, we collected the sera per month and used ELISA to detect the serum antisperm antibodies, The results showed that there are lower antisperm antibody levels in the sera of DMSO, 10% HEMC and 20% HFMC groups in the first 2 months (P less than 0.05), but no significant difference between the antibody levels of DMSO, 10% and 20% HFMC groups and that of the control group from the 3rd month to the 8th month (P greater than 0.05). No immune-related pathological changes were found in the testis and epididymis. Intravas injection of HFMC in the rabbits appears to be a safe method of contraception that causes no deleterious effects.

Animals↗
PubMed1990

Identification of the MAP2- and P75-binding domain in the regulatory subunit (RII beta) of type II cAMP-dependent protein kinase. Cloning and expression of the cDNA for bovine brain RII beta.

cDNA clones coding for the regulatory subunit (RII beta) of type II cAMP-dependent protein kinase were isolated from a bovine brain cDNA expression library in lambda gt11. The cDNA codes for a protein of 418 amino acids which is 98% homologous to the rat and human RII beta proteins. A series of expression vectors coding for truncated RII beta proteins were constructed in pATH plasmids and fusion proteins were expressed in Escherichia coli. Polyclonal and monoclonal antibodies made against purified bovine brain RII were immunoreactive with the fusion proteins on Western blots. The expressed RII beta-fusion proteins were used in overlay assays to identify the region in RII beta which binds to microtubule-associated protein 2 (MAP2) and to the 75,000-dalton calmodulin-binding protein (P75) (Sarkar, D., Erlichman, J., and Rubin, C.S. (1984) J. Biol. Chem. 259, 9844-9846) in bovine brain. Fusion protein containing amino acids 1-50 of the RII beta NH2 terminus (RII beta(1-50)] bound to both MAP2 and P75 immobilized on nitrocellulose filters. A pATH11-directed fusion protein containing the 31 amino acid RII-binding site of the human MAP2 protein (MAP2(31)) (Rubino, H.M., Dammerman, M., Shafit-Zagardo, B., and Erlichman, J. (1989) Neuron 3, 631-638) also bound RII beta-fusion proteins containing RII beta amino acids 1-50. Three fusion proteins, RII beta(1-25), RII beta(25-96), and RII beta(1-265,25-96 deleted) did not bind to MAP2(31) nor P75. The results showed that the binding domain for MAP2 and P75 was located within the NH2-terminal 50 amino acids of RII beta. Preincubation of bovine heart protein kinase II alpha and RII beta(1-50) with MAP2(31) prevented their binding to both P75 and MAP2(31) that were immobilized on nitrocellulose, suggesting that the binding sites for MAP2 and P75 are located near each other or that the same site on RII was binding to both proteins.

A Kinase Anchor Proteins↗
PubMed1990

[Changes in bile composition in rabbits infected with Clonorchis sinensis].

This article presents the changes in the concentration of bilirubin, cholesterol, phospholipid, bile acid and the activity of bacterial beta-glucuronidase in hepatic bile of rabbits infected with metacercariae of Clonorchis sinensis. We found that the activity of bacterial beta-glucuronidase was significantly higher in the infected group (52.6 +/- 31.6 u/dl) than that in control rabbits (12.5 +/- 20.5 u/dl) (P less than 0.001), and no marked changes in the concentration of bilirubin, cholesterol, phospholipid and bile acid were found. concentration of bilirubin, cholesterol, phospholipid and bile acid were found. By using alcian blue-PAS combined stain method the authors also noticed that the amount of glycoprotein in goblet cells has considerably increased and secreted increasingly to the biliary duct after infection with Clonorchis sinensis. As the increase in bacterial beta-glucuronidase activity and glycoprotein in bile is in favour of the formation of pigment stone, this may explain why clonorchiasis is often complicated with cholelithiasis.

Animals↗