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Biomedical subjects

L Zhou

Publications and source records attributed to L Zhou.

At least 559 records · Page 31Linked to original sources
PubMed1993

[The stimulatory effect of dorsal vagal complex injection of pentagastrin on gastric motility in rats].

Changes in antral motility induced by pentagastrin (G5) microinjected into the dorsal vagal complex (DVC) were investigated in fasting conscious rats. Antral motility was monitored by using chronically implanted force transducer sutured to the antrum. DVC injection of G5 markedly stimulated the amplitude of gastric contraction in a dose-dependent manner. The effect, being rapid in onset and long lasting, could not be mimicked by intravenous administration of G5 but could be markedly inhibited by microinjection of antigastrin serum into DVC. Atropine (100 micrograms.kg-1.h-1) and vagotomy could also abolish the G5 induced antral motility. No significant changes in plasma motilin were observed in portal venous blood after administration of G5 in DVC. These results suggested that DVC is an important site of action for G5 induced stimulation of gastric contraction as mediated by vagal cholinergic pathway.

Animals↗
PubMed1993

[Analysis of fatty acid composition of spotted fever group rickettsiae isolated in China by gas chromatography].

In present paper, fatty acid composition of seven Chinese isolates of SFG rickettsiae and six prototype strains of SFG rickettsiae were analyzed by GC-MS. Tested prototype strains of SFG rickettsiae were R. sibirica (strains 232 and 246), R. conorii (Simko), R. rickettsi (R), R. akari (Kaplan), R. australis (W58); Chinese isolates were An-84, Se-85, W-88 (human strain), MT-84, FT-84 (D. nuttalli strain), TO-85 (ova of nuttalli) and Chinese reference strain -JH-74 (D. nuttalli). They were propagated in yolk sacs of embryonated hen eggs and purified by centrifugation in a 30%-36%-42% discontinuous renografin density gradient. The fatty acid composition of selected strains of SFG rickettsiae was analyzed by gas chromatography, and then comparison being carried out by single linkage on mini-computer. Identification of the strains was performed based on the results obtained from GC-MS. Results showed that the fatty acid profiles of all the isolates from China were quantitatively similar to that of R. sibirica and quite different from other prototype strains of SFG rickettsiae.

China↗
PubMed1993

[The effect of high energy shock waves on growth and metastasis of implanted tumors of nude mice in vivo].

We observed the effect of high energy shock waves (HESW) on tumor growth, histological and ultrastructural variations, and metastasis to lymph nodes and viscera in nude mice with implanted tumors. HESW was cytotoxic to tumors in vivo, and acted on levels of cell membrane, cytoplasmic organelles, and nuclear chromatins. At definite working voltage, this effect was positively proportional to the impulse number. Histological examination showed no metastatic focci to lymph nodes and viscera of nude mice with implanted tumors. The possible mechanism of HESW in vivo may be direct mechanical damage and indirect inhibition of tumor growth due to damage to the blood supply. Other hypotheses were also discussed.

Animals↗
PubMed1993

Characterization of a receptor for macrophage inflammatory protein 1 alpha and related proteins on human and murine cells.

Macrophage inflammatory protein 1 alpha (MIP-1 alpha) is a potent stem cell inhibitor and a member of a large and expanding family of related cytokines. In an effort to understand the molecular basis of the activities of MIP-1 alpha, we have sought to characterize the cellular receptors for this molecule. Our results demonstrate the presence of abundant MIP-1 alpha receptors on both human and murine cells. The receptor on K562 cells can bind a range of members of the MIP-1 alpha family and may thus be a general MIP-1 alpha family receptor. Murine FDCPmix cells also bind a range of members of this peptide family, although the receptor(s) that they express appear somewhat more selective for peptides capable of displaying stem cell inhibitory properties. The human and murine receptors do not bind members of the related interleukin 8 family of peptides and are thus distinct from the recently cloned interleukin 8 receptor. We suggest that the receptor on the murine cell is a candidate for the receptor responsible for articulating stem cell inhibitory signals following MIP-1 alpha binding.

Amino Acid Sequence↗
PubMed1993

Influence of recreational activity and muscle strength on ulnar bending stiffness in men.

Bone bending stiffness (modulus of elasticity [E] x moment of inertia [I]), a measure of bone strength, is related to its mineral content (BMC) and geometry and may be influenced by exercise. We evaluated the relationship of habitual recreational exercise and muscle strength to ulnar EI, width, and BMC in 51 healthy men, 28-61 yr of age. BMC and width were measured by single photon absorptiometry and EI by mechanical resistance tissue analysis. Maximum biceps strength was determined dynamically (1-RM) and grip strength isometrically. Subjects were classified as sedentary (S) (N = 13), moderately (M) (N = 18), or highly active (H) (N = 20) and exercised 0.2 +/- 0.2; 2.2 +/- 1.3; and 6.8 +/- 2.3 h.wk-1 (P < 0.001). H had greater biceps (P < 0.0005) and grip strength (P < 0.05), ulnar BMC (P < 0.05), and ulnar EI (P = 0.01) than M or S, who were similar. Amount of activity correlated with grip and biceps strength (r = 0.47 and 0.49; P < 0.001), but not with bone measurements, whereas muscle strength correlated with both EI and BMC (r = 0.40-0.52, P < 0.005). EI also correlated significantly with both BMC and ulnar width (P < 0.0001). Ulnar width and biceps strength were the only independent predictors of EI (r2 = 0.67, P < 0.0001). We conclude that levels of physical activity sufficient to increase arm strength influence ulnar bending stiffness.

Absorptiometry, Photon↗
PubMed1992

Quantitation of human cellular retinoic acid-binding protein II (CRABP-II) RNA from cultured human skin fibroblast cells and human skin biopsies treated with retinoic acid.

A polymerase chain reaction (PCR) method has been validated for the quantitation of retinoic acid (RA) induction of cellular retinoic acid-binding protein II (CRABP-II) RNA from cultured human skin fibroblasts and human skin biopsies. The method utilizes reverse transcription and PCR (RT-PCR) to compare cellular CRABP-II RNA with a known amount of added internal standard RNA generated from a modified CRABP-II cDNA containing a 42 bp deletion. Thus, after RT-PCR of cellular and standard CRABP-II RNA in the same tube, the resulting DNA bands could be distinguished by size on ethidium bromide-stained, nondenaturing polyacrylamide gel. Serial dilutions of cellular RNA were co-amplified with a fixed amount of internal standard CRABP-II RNA, and the ratio of intensities of the two DNA bands was determined by computerized image analysis of the gel photograph. A linear relationship was found between the logs of this ratio and the input RNA. Absolute quantitation of cellular CRABP-II RNA was determined from the 'equivalence point', the dilution at which band intensities from cellular and standard RNAs were identical. Using this quantitative assay, the amount of CRABP-II RNA in cultured fibroblasts was 24 attomoles per microgram total RNA. A 4.2-fold increase in CRABP-II RNA was seen following 24 hours treatment with 10(-6) M RA. CRABP-II RNA content in skin biopsies taken from 3 human subjects ranged from 16 to 25 attomole/micrograms RNA. Topical treatment with 0.1% RA cream resulted in induction ranging from 3.9- to 12-fold over vehicle treatment. The method described here offers a rapid, sensitive and quantitative assay of specific RNAs, and should be especially useful for the measurement of RNA levels from small solid-tissue biopsies.

Base Sequence↗
PubMed1992

Growth regulation of ovarian cancer cells by epidermal growth factor and transforming growth factors alpha and beta 1.

Regulation of ovarian cancer growth is poorly understood. In this study, the effects of EGF, TGF alpha and TGF beta 1 on two ovarian cancer cell lines (OVCAR-3 and CAOV-3) were investigated. The results showed that EGF/TGF alpha stimulated cell growth and DNA synthesis in OVCAR-3 cells, but inhibited cell proliferation and DNA synthesis in CAOV-3 cells. TGF beta 1 invariably inhibited cell proliferation and DNA synthesis in both cell lines. These effects on growth factors are dose dependent. The interaction of TGF beta 1 and EGF/TGF alpha was antagonistic in OVCAR-3 cells. In contrast, EGF/TGF alpha and TGF beta 1 had an additive inhibitory effect on CAOV-3 cells. Our results demonstrated that mature and functional EGF receptors are present in both cell lines and that they are capable of ligand binding, internalization, processing and ligand-enhanced autophosphorylation. Both high- and low-affinity binding are present in these cell lines, with CAOV-3 cells having about 2-3-fold higher total receptors than OVCAR-3 cells. These results together with those from our previous studies show that these cells express TGF alpha, TGF beta 1 and EGF receptors and that cell growth may be modulated by these growth factors in an autocrine and paracrine manner. This report presents evidence supporting the important roles of growth factors in ovarian cancer growth and provides a foundation for further study into the mechanism of growth regulation by growth factors in these cell lines.

Cell Division↗
PubMed1992

Identification of critical amino-terminal regions of XylS. The positive regulator encoded by the TOL plasmid.

The XylS protein is the positive regulator of the promoter controlling the meta-cleavage pathway (Pm) for catabolism of certain alkylbenzoates on the TOL plasmid of Pseudomonas. Transcription from Pm is mediated by XylS either in the presence of benzoate effectors or through XylS hyperproduction. Two regions of the NH2 terminus of XylS (residues 37-45) had been predicted to be involved in effector control of XylS transcriptional activation. Different methods were used to induce mutations in this region, including genetic selections (where Pm controlled a tetracycline resistance gene), bisulfite mutagenesis at a unique restriction site, and extensive oligonucleotide mutagenesis at residues 41 and 45. The mutants fell into four classes based on their phenotypes with respect to effector-mediated activation of a Pm-lacZ fusion: (a) effector profiles similar to wild type, (b) no Pm stimulation with benzoates, (c) altered effector specificity, and (d) higher basal Pm activities, in some cases including changes in effector specificity. In some mutants, higher basal Pm activity was apparently due to mutations that increased XylS stability. Substitutions at Arg-41 resulted in all four mutant phenotypes, indicating that this is a critical residue in XylS for effector stimulation of transcription activity.

Alleles↗
PubMed1992

Attachment of Trypanosoma cruzi to host cells: a monoclonal antibody recognizes a trypomastigote stage-specific epitope on the gp 83 required for parasite attachment.

A set of monoclonal antibodies against the purified surface gp 83 of T. cruzi trypomastigotes was produced and the ability of these monoclonals to inhibit the attachment of trypomastigotes to heart myoblasts was investigated. Western blots of solubilized trypomastigotes, epimastigotes or amastigotes probed with this set of monoclonal antibodies show that the gp 83 is present in invasive trypomastigotes, but not in non-invasive epimastigotes or amastigotes. One monoclonal antibody (Mab 4A4) from this set inhibits the attachment of trypomastigotes to heart myoblasts, whereas the others (MAbs 2H6, 4B9, 2D11) do not. These results show that the Mab 4A4 recognizes an epitope on the gp 83 of invasive trypomastigotes required for parasite binding to host cells.

Animals↗
PubMed1992

Noble metal abundances in an Early Archean impact deposit.

We report detailed analyses on the concentrations of the noble metals Pd, Os, Ir, Pt, and Au in an early Archean spherule bed (S4) of probable impact origin from the lower Fig Tree Group, Barberton Greenstone Belt, South Africa. Compared to other sedimentary deposits of known or suspected impact origin, some noble metals are present in exceptionally high concentrations. Noble metal abundances are fractionated relative to abundances in chondrites with ratios of Os/Ir, Pt/Ir, Pd/Ir, and Au/Ir at only 80, 80, 41, and 2% of these values in CI chondrites. Although an extraterrestrial source is favored for the noble metal enrichment, the most plausible cause of the fractionation is by regional hydrothermal/metasomatic alteration.

Earth, Planet↗
PubMed1992

Metabolic rate modification of nitrotriazole radiosensitizers by sulfur substitution of side chain.

The pharmacokinetic properties and radiosensitizing activities in vitro and in vivo of a series of 3-nitro-1,2,4-triazole (NTA) derivatives with a -CH2(C = Y)NH(CH2)nZCH3 (Y, Z = O or S; n = 2 or 3) group in the side chain at N-1 position of NTA were investigated with respect, particularly, to the effects of sulfur substitution in the side chain of NTA. The sulfur substitution for an oxygen atom in the side chain NTA radiosensitizers increased the rho value, but gave rise to little effect on the one-electron reduction potential. The derivatives bearing a thioether group (-CH2SCH3) in the side chain were slightly less effective both in vitro on hypoxic EMT6/KU cells and in vivo on SCCVII tumors than their oxygen analogs (-CH2OCH3). The thioether compounds tended to metabolize rapidly. The thioamide compound showed high sensitizing activity in vitro, but metabolized very slow.

Animals↗
PubMed1992

Purification of a Trypanosoma cruzi trypomastigote 60-kilodalton surface glycoprotein that primes and activates murine lymphocytes.

We have purified a glycoprotein with a relative molecular mass of 60 kDa and present on the surface of Trypanosoma cruzi trypomastigotes and studied its ability to prime and stimulate the proliferation of murine spleen cells. T. cruzi trypomastigote membrane proteins were separated by preparative isoelectrofocusing. A trypomastigote 60-kDa surface protein with an isoelectric point of 4.2 was enriched by chromatofocusing and was readily purified in native form to homogeneity by gel filtration on a Superose column by use of a fast protein liquid chromatography system. Biotinylated wheat germ agglutinin, Ricinus communis agglutinin, and Datura stramonium agglutinin bound to blots containing the purified trypomastigote 60-kDa surface protein, indicating that this protein was glycosylated. The purified trypomastigote 60-kDa glycoprotein was recognized by antibodies produced during human infection, and immunoglobulin G against the purified glycoprotein immunoprecipitated a biotinylated 60-kDa molecule from the surface of trypomastigotes but not epimastigotes. Specific immunoglobulin G against the 60-kDa glycoprotein also increased the uptake of trypomastigotes and promoted parasite killing by macrophages. The purified 60-kDa glycoprotein was able to specifically activate primed lymphocytes, since there was a significant increase in [3H]thymidine incorporation by spleen cells obtained from CBA mice primed with this glycoprotein, with respect to control values. Furthermore, the 60-kDa glycoprotein did not stimulate unprimed spleen cells, indicating that the lymphoproliferation induced by this glycoprotein was specific and was not due to polyclonal activation. Our findings indicate that this T. cruzi trypomastigote 60-kDa surface glycoprotein primes and activates lymphocytes, which could lead to a beneficial immune response in the host.

Animals↗
PubMed1992

Characteristics of physiological tremor in five fingers and evaluations of fatigue of fingers in typing.

Physiological tremor, which is the invisible mechanical vibration of body part, was measured for five fingers. It was obtained that the power spectrum always has two peaks at 10 and 25Hz for each of the five fingers. The peaks were considered to be generated in the following two loop systems: The component of the lower frequency originated from the central nervous system as a long loop, and that of the higher frequency originated from the muscle-spine loop system as a short loop. The total power, which was the sum of power spectra ranging from 1.5 to 50Hz, was defined as an evaluation index, and it showed characteristic results for the five fingers. The muscular load produced by two hours of typing work was responsible mainly for the increase of total power and for the change of peak frequencies. The mechanism for the change of the power spectrum due to muscular load was well explained by the two-loop theory. It was found that the fatigue of the fingers due to muscular load could be evaluated by the total power.

Adult↗
PubMed1992

Comparison of incidence, mortality and treatment of acute myocardial infarction in hospitals in Japan and China.

Acute myocardial infarction (AMI) is one of the most intractable diseases and is increasing rapidly in Japan and China. Two hospitals in Japan and China, the Critical Care Center of Kurume University Hospital and the Chinese Beijing 309 Hospital in China (abbreviated to Beijing 309 Hospital) were compared. The incidence, mortality and treatment of AMI were investigated in both hospitals from 1989 to 1991. The incidence of AMI for all patients admitted during the three years was 5% in Kurume University Hospital and 4.7% in Beijing 309 Hospital, which are similar rates. The average age of the patients in Beijing 309 Hospital was younger (58 +/- 13) than in Kurume University Hospital (64 +/- 11). The mortality rate in Kurume University Hospital was slightly lower than the rate in Beijing 309 Hospital (8.1% vs 8.9%). Thrombolytic therapy was actively performed in both hospitals. In Kurume University Hospital, urokinase (UK: 71.4%) or recombinant tissue plasminogen activator (rt-PA: 28.6%) was administered by intravenous (85.7%) and intracoronary percutaneous transluminal coronary recanalization (PTCR: 14.3%) injection. In Beijing 309 Hospital, UK (32.7%) or snake poison enzyme (SPE: 62.3%) was administered by intravenous (85.8%) or intra-aortic (14.2%) injection. Rt-PA was only used in Japan and SPE was only used in China, but both had very strong fibrinolytic effects and resulted in high success rates of coronary reperfusion. The incidence of direct coronary intervention with percutaneous transluminal coronary angioplasty (PTCA) and intra-aortic balloon pumping (IABP) for cardiogenic shock was much higher at Kurume University Hospital than at Beijing 309 Hospital.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Radioimmunoassay of serum and CSF myelin basic protein and its application to patients with acute cerebrovascular accident].

Myelin basic protein (MBP) was measured in the serum and CSF of patients with acute cerebrovascular disease (CVD, 34 cases), demyelinating disorders (DMD, 30 cases) and other neurological diseases (OND, 26 cases) by using a double antibody radioimmunoassay (RIA). Patients with acute CVD had a mean serum MBP concentration and positivity rate much higher than those with DMD and OND. The differences were significant (P < 0.05). In CSF, MBP levels in patients with acute CVD and patients with DMD were significantly greater than those in OND patients (P < 0.05). The results also show that there was a linear relationship between the CSF MBP levels and the serum MBP levels in patients with acute CVD (r = 0.72, P < 0.01), but no such relationship in patients with DMD and OND. The amount of serum MBP was also significantly correlated to the severity of acute CVD, to the level of consciousness disorder and limb paralysis, and to the extent and site of the cerebral lesion at CT-scan (P < 0.05). This study shows that the measurement of brain specific MBP in serum as a marker of cerebral damage may have clinical value in the diagnosis and prognosis of patients with CVD.

Cerebral Hemorrhage↗
PubMed1992

[Alteration of calcium uptake and Ca(2+)-ATPase activity of cardiac sarcoplasmic reticulum in rat during ischemia-reperfusion].

Using Langendorff's perfusion model of isolated rat heart, the effect of period of ischemia, ischemia-reperfusion and changes in perfusate pH on the function of calcium uptake of cardiac sarcoplasmic reticulum (SR) was observed. The initial rate and capacity of calcium uptake by SR decreased significantly after 25 min ischemia, and were further worsened when ischemia was prolonged to 40 min. When hearts were subjected to 15 min reperfusion after 25 min ischemia, calcium uptake capacity and initial rate decreased even more in comparison with that of 40 min ischemia. In addition, the calcium dependent ATPase activity of SR was also markedly inhibited. Reperfusion with acid (pH 6.8) or alkaline (pH 8.0) made no significant difference on the aforementioned reperfusion induced changes. The results indicated that myocardial ischemia depressed the calcium transport activity of SR, and this depression was further aggravated with prolonging ischemia. Reperfusion after ischemia exacerbated the ischemic injury. Reperfusion with either acid or alkaline Krebs-Henseleit solution could not improve the calcium uptake function of SR, implying that the pH change does not seem to be an important factor in inducing the SR dysfunction during ischemia-reperfusion.

Animals↗
PubMed1992

[Physiological changes in middle-aged persons and old people before and after tennis competition].

An examination of medical and physiological changes before and after tennis competition was performed on 71 middle-aged persons and old people in order to know whether they were adapted to this intense match or not. The result was that in the male group 1 (50-59 yrs), the heart rate, respiration rate and blood pressure before and after the tennis game had no significant differences (P > 0.05), indicating that this group was fit for the tennis competition, in the male group 2 (60-69 yrs) and male group 3 (70-79 yrs), as age advances, the number of unfitness to this game was increased gradually; in the female group (50-59 yrs), 28.5% of them showed a marked increase in the heart rate after the competition. We think that when persons have an electrocardiogram showing a significant undue changes of the ST segment and T wave after the contest, they are not suitable to this violent competition. So the medical surveillance is very important for the old people to play violent games such as tennis. The periodical health examination should be done before any exercise event with emphasis on the cardiovascular system so that the old sportsman can choose the proper exercise item and take self-control during the exercise.

Age Factors↗