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Biomedical subjects

L Zhu

Publications and source records attributed to L Zhu.

At least 433 records · Page 24Linked to original sources
PubMed1994

[Role of adenosine in weak electro-acupuncture-induced depression of nociceptive response of spinal dorsal horn neurons in rats].

In this study, extracellular recordings were made from wide dynamic range (WDR) neurons in lumbar segments of the spinal cord in rats transsected at the first lumbar segment. The nociceptive discharges of WDR neurons were depressed by weak electro-acupuncture applied to "Yanglingquan"-"Xuanzhong" points. The depression was blocked by i.v. administration of adenosine receptor antagonists, theophylline and caffeine. The observations indicate that depression of the nociceptive response of the WDR neurons induced by weak EA may be mediated by adenosine within the spinal cord.

Adenosine↗
PubMed1994

[Occlusion with interrupted titanium clips for ruptured bullae under video-assisted thoracoscopic surgery].

Spontaneous pneumothorax is a common disease and as many as 20% of these patients should be operated because of a recurrent pneumothorax, persistent air leak, or failure to completely reexpand the lung. From January 1993 until March 1994, on the basis of experiment, we performed video-assisted thoracoscopic surgery (VATS) intervention and talc pleurodesis on 8 patients with spontaneous pneumothorax caused by ruptured bullae, and designed a new procedure of occluding the bullae with interruptured titanium clips. This procedure has some advantages of complete occlusion of lung tissue at the base of the bulla, minimal loss of lung tissue, effectively preventing leakage and recurrent pneumothoraces, and enough capacity of anti-tension while the lung expands. Also Authors have advocated giving a negative pressure suction to opsilateral lumen of the Carlen's tube interbation to visualize adequately the intrathoracic structures, while selective lung ventilation is performed. This method keeps hemodynamic stability and is performed more easily and safely than that of positive pressure insufflation is done. Postoperatively, complete lung expansion was obtained in all patients. There were no perioperative complications related to VATS, and no recurrences to date. These early results with thoracoscopic management of spontaneous pneumothorax caused by ruptured bullae have encouraging.

Adult↗
PubMed1994

[Involvement of purines in analgesia produced by weak electro-acupuncture].

In the present investigation the intensity of stimulated electro-acupuncture (EA) was measured by electrophysiological collision technique. In the behavioral experiments, by applying the weak electro-acupuncture pulses (50 Hz, 1-1.5mA), not enough to activated A delta afferent fibers, to Yanglingquan and Xuanzhong points, the latency of nociceptive hind limb withdrawal reflex, but not tail-flick latency was prolonged. Administered intraperitoneally, both theophylline and caffeine, P1-purinergic (adenosine) receptor antagonists, could block the electroacupuncture-induced elevation of the nociceptive thresholds in a dose-effect related manner, whereas dipyridamole, an inhibitor of adenosine release, could shorten the after of electro-acupuncture in a dose dependent way. These results suggest that weak electro-acupuncture may induce analgesia and purines appear to be involved in this process.

Acupuncture Analgesia↗
PubMed1994

Suspension culture of Catharanthus roseus crown gall cell induced by Agrobacterium C58.

In comparison with calli from leaf or stem, Catharanthus roseus crown gall cell cultured on MS basic medium was superior in growth, total indole alkaloids and ajmalicine contents. The effects of illumination, cultural temperature, sucrose level of the medium and exogenous L-Trp on the growth, total indole alkaloids and ajmalicine contents of C. roseus crown gall cell cultures were studied. The results will provide a theoretical basis for the attempt of using suspension cultures of C. roseus crown gall cells to produce indole alkaloids.

Alkaloids↗
PubMed1993

Quantitative structural comparisons of heme protein crystals and solutions using resonance Raman spectroscopy.

Resonance Raman difference spectra have been used to compare crystal and solution samples of metmyoglobin (metMb), deoxymyoglobin (deoxyMb), and cytochrome P450. At pH 6.0, the frequency shifts of the heme core size sensitive bands v2, v3, and v4 were determined to be less than 0.3, 1.0, and 0.3 cm-1, respectively, for metMb and to be less than 1.0, 1.0, and 0.3 cm-1, respectively, for deoxyMb. This shows that the heme core size differences between the crystal and solution conformations are less than 0.002 A for metMb and less than 0.003 A for deoxyMb. These results disagree with a recent extended X-ray absorption fine structure study [Zhang, K., Chance, B., Reddy, K. S., Ayene, I., Stern, E. A., & Bunker, G. (1991) Biochemistry 30, 9116-9120] which claims that a 0.05-A difference exists in the average iron-ligand distance between the crystalline and solution forms of metMb at pH 6.5. At pH 8.5, metMb solution samples change gradually from a predominantly high-spin to a predominantly low-spin species as the ammonium sulfate concentration is increased to the level found in the crystal mother liquor. No Raman frequency shifts are found between the crystal and solution forms of metMb at pH 8.5 when the ammonium sulfate concentrations are equal. On the other hand, for deoxyMb, we find a significant alteration in the 220/240-cm-1 line shape and relative intensities, suggesting that some histidine-heme perturbation takes place upon crystallization.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonium Sulfate↗
PubMed1993

Tissue-specific expression of phospholipase C encoded by the norpA gene of Drosophila melanogaster.

Mutations in the norpA gene of Drosophila melanogaster severely affect the light-evoked photoreceptor potential with strong mutations rendering the fly blind. Molecular cloning of the norpA gene revealed that it encodes phosphatidylinositol-specific phospholipase C, which enzymes play a pivotal role in one of the largest classes of signaling pathways known. We have used Northern analysis, Western blots, phospholipase C activity assays, and immunohistochemical staining of tissues to examine the tissue-specific expression of the norpA gene and found that it is expressed in a variety of tissues besides the eye. Hybridization of norpA cRNA probe to blots of poly(A+) RNA reveals that the gene encodes at least four transcripts: a 7.5-kilobase (kb) transcript that is expressed in eye and 6.5-, 5.5-, and 5.0-kb transcripts that are expressed in adult body or early stages of development. Antiserum generated against the major gene product of norpA recognizes a 130-kDa protein that is abundant in eyes but severely reduced or absent in norpA mutants, a result which is consistent with previous conclusions that the norpA gene encodes an essential component of the visual system. However, the norpA antiserum also recognizes a 130-kDa protein in adult legs, thorax, and male abdomen, but not female abdomen. These localizations are supported by results of phospholipase C activity assays which show that the norpA mutation reduces phospholipase C activity in each of the tissues in which norpA protein can be detected. Furthermore, immunohistochemical staining of tissue sections with the norpA antiserum demonstrates that the norpA protein is abundant in the retina and ocelli and is present to a lesser extent in the brain and thoracic nervous system. Since some of the above mentioned tissues that express norpA (such as thorax, legs, and abdomen) have no known photoreceptor tissue, we conclude that the norpA gene product is also likely to have a role in signaling pathways other than phototransduction.

Animals↗
PubMed1993

Tissue tolerance to pelvic intraarterial chemoembolization with cisplatin-lipiodol suspension.

Tissue tolerance to pelvic intraarterial chemoembolization with cisplatin-lipiodol suspension was studied in rabbits. Cisplatin (3 mg/kg) was used with different doses of lipiodol (0.0, 0.1, 0.2, and 0.3 ml/kg). Cisplatin-lipiodol suspension was injected into the umbilical artery through a long polyethylene catheter. Local tissue concentration of platinum was increased with lipiodol, while that in the liver, heart, and kidneys was reduced. Tissue retention of platinum was linearly related to the dosage of lipiodol. With a single dose of 0.2 ml/kg lipiodol, only slight degeneration and sparse hemorrhage were observed without necrosis.

Animals↗
PubMed1993

Inhibition of cell proliferation by p107, a relative of the retinoblastoma protein.

The cellular protein p107 shares many structural and biochemical features with the retinoblastoma gene product, pRB. We have isolated a full-length cDNA for human p107 and have used this clone to study the function of p107. We show that, like pRB, p107 is a potent inhibitor of E2F-mediated trans-activation, and overexpression of p107 can inhibit proliferation in certain cell types, arresting sensitive cells in G1. Several experiments, however, showed that growth inhibition by pRB and p107 did not occur through the same mechanism. First, in the cervical carcinoma cell line C33A, p107 was able to block cell proliferation, whereas pRB could not, even though both proteins were potent inhibitors of E2F-mediated transcription in this cell line. Second, growth arrest by pRB and p107 was rescued differentially by various cell cycle regulators. Third, some mutants of p107 that cannot associate with adenovirus E1A were still able to inhibit cell proliferation, whereas analogous mutants in pRB are known to be unable to block cell growth. Together, these results suggest a biological role of p107 that is related, but not identical, to that of pRB.

Adenovirus E1A Proteins↗
PubMed1993

[Relationship between the presynaptic depolarization effect of acupuncture and r-aminobutyric acid, opioid peptide and substance P].

The present study was performed on 22 cats to explore whether r-aminobutyric acid (GABA), endogenous opioid peptide and substance P (SP) were involved in the regulation of presynaptic inhibition in acupuncture analgesia. The size of the antidromic compound C action potentials of the sural nerve evoked by the testing stimulation in spinal cord was measured as an indicator of C-afferent terminal excitability. It was found that the electro-acupuncture (EA) at "Huantiao" (GB30) and "Yang lingquan" (GB34) points induced significant enlargement of the antidromic C-waves, showing the depolarization of presynaptic terminals of primary C-afferents was enhanced. The depolarization effect of EA was significantly reduced by bicuculline, naloxone and the antiserum of SP locally applied to the surface of spinal cord respectively. It is supposed that GABA, endogenous opioid peptide and SP may be involved in the regulation of presynaptic inhibition in acupuncture analgesia.

Action Potentials↗
PubMed1993

[Molecular study on null allolic RFLPs among rice varieties].

Null allele is an allele that produces no functional products. In RFLP analysis, null allele means that one probe can hybridize to plant DNA from one variety readily, but very faintly to DNA from another variety or even has no hybridization signal under experimental stringency and this may be an indication of deletion, insertion or major sequence rearrangement(s) in the corresponding regions. We report here about null alleles of RFLP among 52 rice varieties uncovered with rice random genomic probe RG684. The results show that this kind of null allele is most likely to occur in typical japonica varieties distributed geographically in Northeast China and Japan, and this tendency is consistent with the hypothesis that rice evolved with a trend of from wild type-->Indica-->Japonica. Sequence analysis indicates that the sequence of RG684 has no encoding function. Therefore, changes in this region may not influence the survival of the plant. Comparison of the sequence of RG684 and gypsy transposon bx34e long terminal repeats (LTR) of D. melanogater shows homology of 78.4% of 37 base pair and this leads to the consideration that the occurrence of null alleles in rice is related to transposition or transposition-like events.

Alleles↗
PubMed1993

[The role of OLS in peripheral acupuncture analgesia in arthritic rats].

Our previous work has shown that opiate-like substance (OLS) is involved in the central mechanism of acupuncture analgesia (AA) in the arthritic rats. In this paper, the role of OLS in peripheral mechanism of AA is further studied. Twenty four hours after a subcutaneous injection of Freund's adjuvant into the right ankles, acute arthritis with typical symptoms developed in all the rats. Following needling at Huantiao points for 10 minutes, the pain threshold (PT) was raised by 42.3% (P < 0.05) in the inflamed ankles and by 5.6% in the non-inflamed ones. When systemically administered a dose of 250 and 100 micrograms, naloxone (Nx) could completely and partially (49.6%) block AA respectively. While locally injected a dose of 100 micrograms even 20 micrograms, Nx could completely antagonize AA. After systemic administration of morphine (10, 5.0, 2.5, 1.25 mg/kg), PT rise was dose-related, and PT was raised by 86.5 +/- 22.7% in the affected ankles and by 32.9 +/- 14.9% in the normal ankles at 5 mg/kg in dose. It is evident that the opiate receptors in the inflamed area should by sensitized. These results demonstrate that activation of endogenous opiate system may also be involved in the peripheral AA. Acupuncture may enhance the release of peripheral OLS which can act at the sensitized opiate receptors, leading to more potent analgesic effect in the inflamed area.

Acupuncture Analgesia↗
PubMed1993

A developmentally regulated program restricting insolubilization of elastin and formation of laminae in the fetal lamb ductus arteriosus.

BACKGROUND: The ductus arteriosus (DA) is a fetal vessel in which the elastic laminae fail to assemble normally in late gestation. This feature is associated with the development of intimal cushions, structures that partially occlude the DA lumen and assure that the vessel will close completely when it constricts postnatally. EXPERIMENTAL DESIGN: We studied the fetal lamb DA at two different gestational time-points, 100 days before, and 138 days coincident with intimal cushion formation (term = 145 days) to establish the ultrastructural basis for the 'disassembly' of elastic laminae apparent on light microscopy and to determine further whether the mechanism was due to increased elastolytic activity, decreased synthesis of tropoelastin, or impaired insolubilization of tropoelastin. RESULTS: Morphometric ultrastructural analyses of tissue from the 138-day gestation fetal lambs revealed that the volume density of elastin in the DA vessel wall was only 40% of that in the aorta (Ao) and 50% of that in the pulmonary artery (PA). Moreover, only 16% of the elastin present contributed to the formation of laminae when compared to 80% in the Ao and 50% in the PA. Despite the morphologic appearance of 'fragmented' elastin, there was no evidence of increased elastolytic activity in the DA at either gestational time-point as judged by solubilization of a [3H] elastin substrate. The reduced elastin apparent was morphologically accompanied by an increase in soluble (tropo) elastin in DA compared with Ao and PA, as measured by enzyme linked immunosorbent assay, in tissue from both 100- and 138-day gestation lambs. Lack of differences in tropoelastin mRNA levels when comparing the 3 vessels suggested that the enzyme linked immunosorbent assay measurements reflected increased DA tropoelastin accumulation owing to lack of insolubilization rather than an increase in synthesis. Reduced insolubilization of newly synthesized elastin was evident in the DA compared with the Ao at 100 days gestation and in the DA compared with both Ao and PA at 138 days gestation in association with reduced desmosine levels. CONCLUSIONS: The mechanism of the decrease in tropoelastin insolubilization was unrelated to lysyl oxidase activity in the tissue and represents a unique developmental program.

Animals↗