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Biomedical subjects

J Shi

Publications and source records attributed to J Shi.

At least 253 records · Page 14Linked to original sources
PubMed1997

Effects of 17beta-estradiol on glucose transporter 1 expression and endothelial cell survival following focal ischemia in the rats.

Estrogen replacement therapy in postmenopausal women is associated with a decreased mortality and morbidity from stroke. The present study was undertaken to investigate the effects of estrogen on endothelial cell glucose transporter 1 (GLUT 1) and on the cell viability during focal ischemia in a rat model. Female rats were ovariectomized (OVX) and 2 weeks later 17beta-estradiol (E2) was injected subcutaneously at a dose of 100 microg/kg 2 h before unilateral middle cerebral artery (MCA) occlusion. Ischemic lesion size was quantified using 2,3,5-triphenyl tetrazolium chloride (TTC) staining and GLUT 1 protein was analyzed by Western blotting. E2 treatment decreased ischemic lesion size in slices taken at 9 and 11 mm posterior from the olfactory bulb by 46.3% and 44.1%, respectively (P < 0.05). GLUT 1 protein decreased in both OVX and E2 groups by 24.6% and 22.7% respectively (P < 0.05) compared with the non-lesioned side in the core ischemic region, including the basal ganglia. GLUT 1 protein was increased in the E2-treated group compared with the control group (23.3%, P < 0.05) in the penumbral ischemic region of the cortex. Primary rat brain capillary endothelial cell (BCEC) cultures were established as an in vitro model for ischemic effects on endothelial cells. Estrogen reduced BCEC loss by 35.9%, 28.4% and 23.5% (P < 0.05) when glucose in the culture medium was reduced to 50%, 20% and 10%, respectively; and by 28.4% and 18.4% (P < 0.05) following 1 or 4 h of anoxia, respectively. This study demonstrates that estrogen treatment increases GLUT 1 transporters and protects BCEC loss which may in turn reduce focal ischemic brain damage.

Animals↗
PubMed1997

Remodeling of pineal epithelium in the fetal rat as delineated by immunohistochemistry of laminin and cadherin.

Epithelial remodeling in the rat pineal during fetal development was immunohistochemically analyzed by using antibodies for laminin and cadherin as molecular markers of basal lamina and intercellular junctions, respectively. The proliferation and differentiation of pinealocytes were also investigated in relation to the advance of epithelial remodeling. The pineal anlage of embryonic day 16 is completely covered by basal lamina immunolabeled for laminin. After embryonic day 17, local dissolution of the basal lamina occurs on the epithelial folds, which develop predominantly in the rostral pineal wall. Some pineal cells migrate through these interruptions and form cellular aggregations outside the basal lamina. Cadherin immunostaining reveals focal dissolution of intercellular junctions in epithelial regions protruding into the pineal lumen. Dissolution of the basal lamina and intercellular junctions accompanied by cellular migration into the stromal tissue or into the pineal lumen continues until birth. The distribution of mitotic cells immunolabeled for BrdU is homogeneous throughout the organ during the fetal period, whereas that of differentiating pinealocytes immunoreactive for synaptophysin shows striking regional heterogeneity in close correlation with the remodeling of the pineal epithelium. The migrating cell populations located either outside the basal lamina or inside the pineal lumen are more liable to become synaptophysin-positive than the rest of the epithelium. These results suggest that epithelial remodeling in the fetal pineal is induced, at least in part, by epithelial infolding and that this remodeling promotes the differentiation of pinealocytes.

Animals↗
PubMed1997

New spin labeled analogues of podophyllotoxin as potential antitumor agents.

Four new nitroxyl labeled derivatives of podophyllotoxin, 4-(2, 2, 6, 6-tetramethyl-1-oxyl-4-piperidyl)oxy-epipodophyllotoxin (4), 4-(2, 2, 6, 6-tetramethyl-1-oxyl-4-piperidyl)oxy-4'-demethylepipodophyllotoxin (5), 4-(2, 2, 5, 5-tetramethyl-1-oxyl-3-pyrrolinyl)formyloxy-epipodophyllotox in (6) and 4-(2, 2, 5, 5-tetramethyl-1-oxyl-3-pyrrolinyl)formyloxy-4'-demethylep ipodophyllotoxin (7), have been synthesized and evaluated for their antitumor activity in vitro. Compounds 5 and 7 showed superior activity to clinically used etoposide (VP-16,2) in their inhibition of leukemia P388, lung cancer A549 and stomach carcinoma SGC-7901 cells. 4'-Demethyl-epipodophyllotoxins 5 and 7 was found to be more active than eipodophyllotoxins 4 and 6 lacking a free phenolic hydroxyl group at C-4'.

Animals↗
PubMed1997

The determination of vasoactive substances during autonomic dysreflexia.

Urinary bladder percussion induced autonomic dysreflexia (AD) was observed in spinal cord injured patients with a complete neurological lesion, the upper level being above T5. To document the pathology and study the etiology of autonomic dysreflexia to further investigate its mechanism, this paper presents some clinical data on the determination of vasoactive substances such as norepinephrine (NE), epinephrine (E), renin (R), angiotensin II (AII) and atrial natriuretic polypeptide (ANP) before and during bladder percussion in 30 patients with a thoracolumbar or cervical spine and spinal cord injury. It is demonstrated that tapping the urinary bladder of such patients can cause AD. Changes of some of the vasoactive substances in the plasma were also observed, which might indicate that autonomic dysreflexia result from excitation of the sympathetic nervous system. Overactivity of the sympathetic nervous system was antagonized by excitation of the vegetative nerve system. There was no correlation between changes of blood pressure and adrenal function as well as the change of R-A II system; during autonomic dysreflexia, the inclement of ANP secretion played an important role in recovering homeostasis.

Adult↗
PubMed1997

Performance evaluation of a diode array for enhanced dynamic wedge dosimetry.

The performance of a diode array (Profiler) was evaluated by comparing its enhanced dynamic wedge (EDW) profiles measured at various depths with point measurements using a 0.03 cm3 ionization chamber on a commercial linear accelerator. The Profiler, which covers a 22.5 cm width, was used to measure larger field widths by concatenating three data sets into a larger field. An innovative wide-field calibration technique developed by the manufacturer of the device was used to calibrate the individual diode sensitivity, which can vary by more than 10%. Profiles of EDW measured with this device at several depths were used to construct isodose curves using the percentage depth dose curve measured by the ionization chamber. These isodose curves were used to check those generated by a commercial treatment planning system. The profiles measured with the diode array for both 8 and 18 MV photon beams agreed with those of the ionization chamber within a standard deviation of 0.4% in the field (defined as 80% of the field width) and within a maximum shift of less than 2 mm in the penumbra region. The percentage depth dose generally agreed to within 2% except in the buildup region. The Profiler was extremely useful as a quality assurance tool for EDW and as a dosimetry measurement device with tremendous savings in data acquisition time.

Humans↗
PubMed1997

Porcine polymorphonuclear leukocytes generate extracellular microbicidal activity by elastase-mediated activation of secreted proprotegrins.

Antimicrobial peptides of several structural classes have been found in phagocytes and epithelial cells of many animals. The broadly microbicidal protegrins (PG1, -2, and -3) were originally isolated as 16 to 18-amino-acid peptides from pig neutrophil lysates, but the corresponding cDNA sequences encoded much larger precursors that belonged to the cathelicidin family of antimicrobial peptides. We explored the storage, secretion, and microbicidal activation of protegrins in porcine neutrophils and in a model system consisting of recombinant proprotegrin 3 (pPG3) and various serine proteases and their inhibitors. Protegrins were stored in neutrophils as inactive proforms that were cleaved by neutrophil elastase to mature protegrins during the preparation of granule lysate and during phorbol myristate acetate-stimulated granule secretion from intact neutrophils. Recombinant pPG3 was efficiently cleaved by trace amounts of human neutrophil elastase or equivalent amounts of elastase activity from porcine neutrophils, but pPG3 was relatively resistant to porcine pancreatic elastase or human neutrophil cathepsin G. The recombinant pPG3 and neutrophil proprotegrins lacked microbicidal activity, but the mature protegrins generated in the elastase-mediated cleavage reaction were as active against Listeria monocytogenes as the chemically synthesized protegrin. The secretion and elastase-mediated activation of proprotegrins accounted for much of the stable microbicidal activity of porcine neutrophil secretions against L. monocytogenes. Secreted proprotegrins and trace amounts of elastase constitute a binary microbicidal system that is likely to contribute to the antimicrobial activity of porcine inflammatory fluids.

Amino Acid Sequence↗
PubMed1997

Characterization of the nitric oxide reductase-encoding region in Rhodobacter sphaeroides 2.4.3.

A gene cluster which includes genes required for the expression of nitric oxide reductase in Rhodobacter sphaeroides 2.4.3 has been isolated and characterized. Sequence analysis indicates that the two proximal genes in the cluster are the Nor structural genes. These two genes and four distal genes apparently constitute an operon. Mutational analysis indicates that the two structural genes, norC and norB, and the genes immediately downstream, norQ and norD, are required for expression of an active Nor complex. The remaining two genes, nnrT and nnrU, are required for expression of both Nir and Nor. The products of norCBQD have significant identity with products from other denitrifiers, whereas the predicted nnrT and nnrU gene products have no similarity with products corresponding to other sequences in the database. Mutational analysis and functional complementation studies indicate that the nnrT and nnrU genes can be expressed from an internal promoter. Deletion analysis of the regulatory region upstream of norC indicated that a sequence motif which has identity to a motif in the gene encoding nitrite reductase in strain 2.4.3 is critical for nor operon expression. Regulatory studies demonstrated that the first four genes, norCBQD, are expressed only when the oxygen concentration is low and nitrate is present but that the two distal genes, nnrTU, are expressed constitutively.

Amino Acid Sequence↗
PubMed1997

Characterization and regulation of the gene encoding nitrite reductase in Rhodobacter sphaeroides 2.4.3.

Nitrite reductase catalyzes the reduction of nitrite to nitric oxide, the first step in denitrification to produce a gaseous product. We have cloned the gene nirK, which encodes the copper-type nitrite reductase from a denitrifying variant of Rhodobacter sphaeroides, strain 2.4.3. The deduced open reading frame has significant identity with other copper-type nitrite reductases. Analysis of the promoter region shows that transcription initiates 31 bases upstream of the translation start codon. The transcription initiation site is 43.5 bases downstream of a putative binding site for a transcriptional activator. Maximal expression of a nirK-lacZ construct in 2.4.3 requires both a low level of oxygen and the presence of a nitrogen oxide. nirK-lacZ expression was severely impaired in a nitrite reductase-deficient strain of 2.4.3. This suggests that nirK expression is dependent on nitrite reduction. The inability of microaerobically grown nitrite reductase-deficient cells to induce nirK-lacZ expression above basal levels in medium unamended with nitrate demonstrates that changes in oxygen concentrations are not sufficient to modulate nirK expression.

Aerobiosis↗
PubMed1997

17 beta-Estradiol modulation of glucose transporter 1 expression in blood-brain barrier.

The present study was designed to evaluate 17 beta-estradiol (E2) modulation of glucose transporter 1 (GLUT-1) protein and mRNA expression in blood-brain barrier (BBB) endothelium. Female rats were ovariectomized (OVX) for 12-14 days, then E2 was injected at dosages of 1-100 micrograms/kg sc at 2-16 h before sampling. Glucose transport into BBB endothelial cells was assessed using 2-deoxy-[14C]glucose (2-[14C]DG) uptake. GLUT-1 protein and mRNA samples were analyzed by Western and Northern blotting, respectively. E2 treatment caused dose- and time-dependent increases in 2-[14C]DG uptake and GLUT-1 protein expression by microvessels. The peak responses were induced by 10 micrograms/kg E2 dose at the 4-h sampling time (36.0 and 31.3% increases, P < 0.05, respectively). GLUT-1 mRNA demonstrated a transient increase at 15 min (55%, P < 0.05), then decreased to basal level by 2 h. This study shows that in vivo treatment with E2 increases 2-[14C]DG uptake into the BBB endothelial cells and suggests this E2 effect is due to its modulation of GLUT-1 mRNA and protein.

Animals↗
PubMed1997

Urine-derived compound evokes membrane responses in mouse vomeronasal receptor neurons.

Sensory neurons of the vomeronasal organ (VNO) are thought to detect species-specific chemical signals important for reproductive function. The electrical properties of VNO neurons have begun to be characterized in a variety of species; however, the response of VNO neurons to possible physiological ligands has not yet been reported. One physiological effector, dehydro-exo-brevicomin (DHB), is found in the urine of intact male mice and affects the estrous cycle of female mice. In the present study, dissociated VNO neurons were voltage- or current-clamped and their response to DHB was determined. Approximately 26% of VNO neurons responded to DHB with an outward current at negative holding potentials; the current reversed at approximately +4 mV. Application of DHB in current-clamp mode produced membrane hyperpolarization and/or a reduction in the firing of action potentials. Because membrane conductance was shown to be decreased during application of DHB, the results suggest that the outward current associated with DHB application is a reflection of a reduction in inward current caused by closing an ion channel. This study provides the first evidence that a compound found in male urine directly affects VNO neurons.

Animals↗
PubMed1997

[Proliferative activities, oncoprotein expression and their significance in human gliomas].

OBJECTIVE: To explore the relationship between the proliferative activities, oncoprotein expression, cell differentiation and prognosis of gliomas. METHODS: Immunohistochemistry and image analysis were used to study the expression of proliferating cell nuclear antigen (PCNA) and several oncoproteins both qualitatively and quantitatively in 124 brain gliomas. RESULTS: It was found that the intensities of PCNA reaction were significantly related to both the grade and prognosis of gliomas. Overexpression of c-erbB-2 protein was slightly stronger in well than in poorly-differenciated gliomas. Moreover, the reactions in patients who survived over 5 years were stronger than in those under 5 years. EGF (40.0%), EGFR (91.4%) and p21ras (53.3%) expression levels were related to neigher the grading nor prognosis of this tumor. The positive ratios of the three antibodies to p53 protein were higher in grades II-IV than in grade I gliomas. The intensity of p53 reaction was correlated to that of PCNA. CONCLUSION: It is suggested that the aberration of c-erbB-2, p21ras, EGF and EGFR might be the early events in the initiation and progression of gliomas, whereas p53 is involved in all stages of these tumors. PCNA could reflect the degree of malignancy to a certain extent.

Brain Neoplasms↗
PubMed1997

[Neoplasm-inhibiting effect and sensitivity-promoting effect of indomethacin in vitro].

OBJECTIVE: To explore an anti-tumor effect of indomethacin on human colon adenocarcinoma cell line HCT116, and its mechanism. METHODS: MTT, agarose gel electrophoresis, TdT and flow cytometry were used to study cell proliferation and apoptosis. RESULTS: Indomethacin significantly inhibited the proliferation of HCT116 cells and induced apoptosis with a "dose-time" dependent pattern. A synergic effect of inhibiting cancer cells proliferation was observed when combined with 5-Fu. CONCLUSION: Inhibition of proliferation and induction of apoptosis contribute to the mechanisms for anti-tumor activity of indomethacin.

Adenocarcinoma↗
PubMed1997

[Effect of different training time and loads on the metabolism of carbohydrate, fat and protein].

Twenty-five athletes were selected to receive three kinds of loads (endurance, strength and sprint training) at the same training time, as well as to receive the same kind of load at different time (morning, am. pm), then the tricarboxylic acid (TCA) cycle products, free fatty acids (FFA), urea nitrogen, creatinine and free amino acids contents in their serum were measured. The results showed that at the same training time, different loads led to different physiological effects, while the same kind of exercise training resulted in more protein catabolism in p.m. than in the morning or a.m. Endurance or training in the morning had considerable influence on the levels of TCA cycle products and FFA components. Training in p. m. may be favourable to improving the quality of the sports of speed and strength.

Adolescent↗
PubMed1997

[Effects of nordihydroguaiaretic acid on the growth and differentiation of SHG-44 glioma cell line].

OBJECTIVE: To investigate the effects of nordihydroguaiaretic acid (NDGA) on the growth and differentiation of glioma cells and their mechanism. METHODS: A human glioblastoma cell line (SHG-44) was treated with NDGA in the medium or intracytoplasmic microinjection of NDGA. Changes of the growth, morphology, cell cycle and immunohistochemical features of the cell were investigated. RESULTS: It was found that the growth rates and proliferation activity were inhibited by 100 mumol/L NDGA in the medium, with cell cycles altered. NDGA could induce differentiation of these cells with the glial filaments increased, and the treated cells expressed more GFAP but less vimentin. The expression of p53 and bFGF were also decreased. Furthermore, the result of microinjection (1.5 x 10(-11) g/cell) showed similar but more rapid and permanent effects on the glioma cells. CONCLUSION: NDGA has multiple effects of growth inhibition, differentiation therapy, as well as angiosuppression on human glioblastoma cells.

Brain Neoplasms↗
PubMed1997

[Photographic diagnosis for common intraorbital tumors].

OBJECTIVE: To compare and analyze the modern photographic methods used for localization and analysis of the nature of intraorbital tumors. METHODS: B-scan, CT scan and magnetic resonance imaging (MRI) were used to examine six types of common intraorbital tumor (20 cases for each type). RESULTS: Each method can locate and show the nature of the lesions, and B-scan has a better value to display internal structure and dynamics of orbital lesions. CT can discover the lesions and exactly show their locations, while MRI is more valuable to display the optic nerve tumor and the extension of intraorbital tumor to extraorbital regions. CONCLUSIONS: All the above methods can locate and show the nature of intraorbital tumors, and each has its own special defects and advantages which can be complementary to one another.

Dermoid Cyst↗
PubMed1997

Effect of radix Salviae miltiorrhizae on extracellular adenosine and evaluation of its protective efficacy in ischemic reperfusion rat--microdialysis, HPLC and histopathologic studies.

The effects of Radix Salviae Miltiorrhizae (RSM) on extracellular adenosine (Ade) and its metabolites, i.e. inosine, hypoxanthine and xanthine, were studied with microdialysis and HPLC techniques during cerebral ischemia-reperfusion induced by 4-vessel occlusion in rat brain. Histological examination of hippocampus was performed 6 h after reperfusion. ECF (extracellular fluid) adenosine and its metabolites were compared between the controls (n = 6) and RSM-treated rats (n = 6). Basal level of Ade and its metabolites release were not greatly affected by pretreatment with RSM, and no significant difference as compared with the sham-operated (n = 6). Ade and its metabolites were dramatically increased after ischemia, and decreased near basal-level and its metabolites remained high at the end of reperfusion. In the RSM-treated animals, the tendency of changes of Ade and its metabolites was just the same as in the controls, but the magnitudes of changes were significantly lower at some different time points. In sham-operated animals, no changes were observed at different time points both during ischemia (30 min.) and reperfusion (60 min.). Histopathological findings demonstrated that RSM pretreatment results in better histologic preservation of the pyramidal cells in the postischemic reperfusion CA1 sector both qualitatively and quantitatively. These results indicated that RSM protects against cerebral ischemia reperfusion injury.

Adenosine↗
PubMed1997

[The changes and clinical significance of serum CRP, C3, Tf, and PA in the early postburn stage].

The aim of this study was to investigate the regulation and clinical significance of serum acute phase proteins. The patients were divided into three groups: group I consisted of 11 patients with less than 20% of TBSA; group II 10 patients with 20-50% of TBSA and group III 11 patients with more than 50% of TBSA. Blood samples were taken at 8, 24, 48 and 72 h postburn, and in group III additional blood samples were taken on the 7th, 14th, 21st day or in septic episode. The concentration of CRP and C3, Tf, PA were detected by rate nephelometry, agar immunodiffusion and rocket immunoelectrophoresis respectively. Compared with controls, the peak value of CRP was observed during 48-72 h (P < 0.01), C3 decreased at 8 h and lowest at 24 h. Tf was lowered at 48 h, PA and Tf shared the similar changes. However, all four variables had no marked difference during infection and sepsis. The results showed no correlation between C3 and CRP (r = 0.0885, P > 0.05). The results suggested that: 1. CRP mainly reflected the extent of injury but not sepsis; 2. increased CRP was not the causative factor of decreased C3. Tf reduction accelerated bacterial growth.

Adult↗