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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,441 records · Page 80Linked to original sources
PubMed1992

[Involvement of acetylcholine in corticofugal modulation of pain].

We have found that after intraperitoneal injecting atropine the analgesic effect of both stimulating Sm I cortex and acupuncture were decreased. It suggests that acetylcholine (ACh) may be involved in the corticofugal modulation of pain. In order to elucidate this idea the effects of stimulating Sm I cortex on tail flick latency (TFL) after ventrical microinjecting atropine were investigated. The experiments were carried out on Wistar rats. Under the state of anaesthesia a pair of silver ball electrodes were put on the dura for electrical stimulating Sm I and the ipsilateral ventricle was cannulated for microinjecting atropine. Recordings were made 5-6 hours or 24 hours after operation. Immediately after cessation of stimulating SmI and 1', 2', 3.5', 5', 7.5', 10' and 15' later TFL were measured consecutively. The results were as follows: 1. The mean value of TFL was 2.44 +/- 0.11 sec (n = 20). It was prolonged (p < 0.05) within 0'-5' after stimulation of SmI. Therefore, it indicated that analgesic effects were produced by stimulating SmI cortex. 2. It was found that under the background of microinjecting atropine (10 micrograms/2 microliters) TFL remained unchanged after stimulating SmI cortex (n = 10, P > 0.05). There was a significant difference between the two treatments: simple stimulating SmI and atropine plus stimulating SmI at the same animals in TFL (P < 0.05) within 0' and 1' after cessation of stimulating SmI. It indicated that the analgesic effects of stimulating SmI cortex were decreased by blocking M-receptors. 3. Under the background of microinjecting normal saline.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1992

Purification and partial characterization of an antibacterial protein LCIII.

Total proteins were precipitated by (NH4)2SO4 from the overnight culture supernatant of antagonistic bacterium Bacillus subtilis A014, applied to CM52 column and separated into three main peaks. The preparation of peak III showed to inhibit specifically the growth of rice bacterial blight pathogen Xanthomonas compestris pv. oryzea was further purified with Mono S column on FPLC and named antibacterial protein LCIII. The molecular weight of this protein is 26915Da, pI = 9.12. Analysis of amino acid composition was revealed to be rich in glycine, threonine and serine, and devoid of proline. Twenty-eight amino acids of N-terminal were sequenced by the Edman degradation and computer analysis of this partial sequence showed that antibacterial protein LCIII is a novel one.

Amino Acid Sequence↗
PubMed1992

[Studies of outer membrane protein profiles by SDS-PAGE for Campylobacter jejuni in an epidemiological investigation].

The characteristics of outer membrane protein profiles of 41 strains of Campylobacter jejuni from various sources by SDS-PAGE was studied. Seven and nine OMP patterns were differentiated respectively by the presence or absence of six outer membrane protein bands and by the number and size of the molecular weight of the major protein bands. Comparing the OMP patterns of the strains from human with those from animals, the authors inferred that chickens and other animals might be one of the sources for the human infection of Campylobacter jejuni in this district. A comparison between the OMP patterns of the strains from diarrheic children and those from healthy carriers suggested that the pathogenesis of Campylobacter jejuni be possibly associated with the outer membrane proteins. Using the techniques, the authors studied the infection of Campylobacter jejuni in a nursery. The result showed the infection was sporadic and of multi-sources, as evidenced by the multi-patterns of the outer membrane protein profiles. It also indicates that the person-to-person transmission plays a significant role in the infection of Campylobacter jejuni.

Animals↗
PubMed1992

Molecular rearrangements of the MYL gene in acute promyelocytic leukemia (APL, M3) define a breakpoint cluster region as well as some molecular variants.

Genomic DNA probes generated from the retinoic acid receptor alpha (RARA) gene located on chromosome 17 and from the MYL gene located on chromosome 15 were used to study the chromosome 15 breakpoints resulting from the t(15; 17) translocation in 26 patients with acute promyelocytic leukemia (APL). In 20 out of 22 patients with a detectable MYL rearrangement, the breakpoints were clustered within a 4.4 kb segment designated MYLbcr. The two remaining patients exhibited a more 5' rearrangement at about 10 kb upstream of the MYLbcr region, implying the lack of at least one MYL gene exon in the resulting MYL-RARA fusion gene. The variation of chromosome breakpoints within the MYL gene may explain size heterogeneity previously observed in some MYL-RARA fusion transcripts expressed in APL cells.

Blotting, Southern↗
PubMed1992

[Corticofugal modulation of somatosensory area II on acupuncture effect in nucleus ventralis posterolateralis of the thalamus].

In order to explore whether cortical somatosensory area 11 (SII) was involved in descending modulation of the effect of electroacupuncture (EA) on nucleus ventralis posterolateralis (VPL), the present study was designed to investigate the influence of topical application of lidocaine at SII on the EA effects in VPL nucleus. Experiments were performed on 23 adult cats anaesthetized with pentobarbital sodium (35-40 mg/kg i.p.) and immobilized with gallamine triethiodide. The single unit activities of VPL neurons were extracellularly recorded using glass microelectrodes. The results were as follows: 1. The nociceptive responses of VPL were obviously attenuated after EA at "Huantiao (G30)" and "Yanlingquan (G34)". The difference was statistically significant at 0-10 minutes after cessation of EA (n = 13, P < 0.001 or P < 0.05), then it was gradually recovered. The results showed that EA could inhibit the nociceptive responses of VPL neurons. 2. The inhibitory effect of acupuncture on nociceptive responses were reduced or abolished after topical application of lidocaine (n = 14, P > 0.05). However, it exerted marked inhibition at 0-10 minutes after cessation of EA in the saline control group (n = 14, P < 0.05). There was a statistical difference between these two groups (P < 0.05). The results showed that SII was involved in descending modulation of acupuncture effect in VPL nucleus.

Acupuncture Analgesia↗
PubMed1992

Effects of ammonium and lactate on hybridoma cell growth and metabolism.

The effects of ammonium and lactate at different concentrations on the growth of 2F7 hybridoma cells, involving glucose consumption, lactate accumulation and cell viability, are investigated. The results suggest that growth inhibition occurs at 2.5 mM ammonium and 2.5 mg/ml lactate, and that severe inhibition occurs at 5 mM ammonium and 5.0 mg/ml lactate.

Ammonia↗
PubMed1992

Hemodynamic observation and treatment approach for patients with angina decubitus.

In order to investigate the mechanism and treatment of angina decubitus, 20 patients (18 men and 2 women aged 36-70 years) were studied during hospitalization. All patients were found to have an increased heart rate x systolic blood pressure product before the onset of angina decubitus, indicating that this type of angina pectoris belongs to the category of effort angina. Of the 11 patients investigated by continuous hemodynamic monitoring, 3 had significant progressive increases in pulmonary artery systolic pressure (PASP) and pulmonary artery diastolic pressure (PADP) before onset: their episodes of angina could not be completely controlled by digoxin and diuretics, but quickly subsided after beta blockers were added. Among the other 8 patients, PADP increased slightly in 5 and remained unchanged in 3 cases before onset: these patients had no manifestations of LV dysfunction, and beta blockers combined with coronary vasodilators produced satisfactory effects. These results indicate that LV failure is not a major factor in the pathogenesis of angina decubitus. The LV diastolic dysfunction seen in 8/11 cases may have been related to LV hypertrophy caused by long-term hypertension or chronic persistent ischemia.

Adrenergic beta-Antagonists↗
PubMed1992

Occurrence of distinct PML-RAR-alpha fusion gene isoforms in patients with acute promyelocytic leukemia detected by reverse transcriptase/polymerase chain reaction.

A specific 'nested' reverse transcriptase/polymerase chain reaction (RT/PCR) procedure was used to characterize the expression patterns of PML-RAR-alpha chimeric mRNAs in 32 patients with acute promyelocytic leukemia (APL). The sensitivity of the technique was such that the fusion gene transcript could be detected from as little as 2.5 pg of total leukemic cell RNA against a background of 1 microgram of cellular RNA lacking the PML-RAR-alpha fusion gene transcript(s). In 19 cases the PML-RAR-alpha isoform referred to here as long was identified. A short isoform, which in comparison with the long form lacks three PML exons, was detected in 11 other cases. A third PML-RAR-alpha mRNA isoform, in which the most 3' PML exon present in the long-type isoform was truncated in its sequences lying immediately upstream of RAR-alpha B region, was found and characterized in a single patient. In one APL patient with a variant translocation t(11;17), the PCR product corresponding to PML-RAR-alpha chimeric mRNAs could not be amplified despite the presence of RAR-alpha gene rearrangement. Genomic and PCR analysis showed that the different PML-RAR-alpha isoforms found in APL patients arise as a result of distinct translocation breakpoints. In each case the exons encoding the B-F regions of RAR-alpha are expressed and are spliced downstream from variable PML gene exons. The 'nested' RT/PCR analysis of the PML-RAR-alpha fusion gene proved to be a rapid and sensitive tool for the diagnosis of the APL and for monitoring the residual APL chimeric mRNA expression during complete remission.

Adolescent↗
PubMed1992

[Plasmid analysis and antibiotic resistance pattern measurement of Shigella in Chengdu].

A total of 81 strains of Shigella isolated from sporadic cases and cases in an outbreak of Shigella sonnei infection was analysed by plasmid profiles and antibiotic resistance patterns. The strains had a high resistance patterns. The strains had a high resistance of ampicillin, tetracycline, trimethoprim-sulfamethoxazole and chloramphenicol; while 97.2% of the strains were susceptible to gentamicin, kanamycin. The results showed that 50% of the strains harbored plasmid patterns within each species, which indicated that many genetically different strains of Shigella were responsible for dysentery epidemics in Chengdu. According to the results of the plasmid analysis and antibiotic resistance pattern measurement made in the outbreak strains, it was clearly seen that most of the strains were similar or fundamentally similar, which suggested that one or two strains with genetical homology were the main causative agent for the outbreak. We think that plasmid profiles and antibiotic resistance patterns are applicable to the identification of the outbreak strains of dysentery as an efficient epidemiologic tool.

Ampicillin Resistance↗
PubMed1992

Quantitative assessment of regional wall motion abnormalities with 2DE in cases of myocardial infarction.

The severity, extent and localization of regional wall motion abnormalities (RWMA) were quantitatively assessed with apical biplane two-dimensional echocardiography (2DE) using a fixed-axis system, ten-segment division area method in 56 patients with old myocardial infarction (OMI). RWMA were found to be more severe in the anterior wall MI (AWMI) group than in the inferoposterior wall MI (IWMI) group and most severe in the extensive AWMI with ventricular aneurysm (EAWMI with VA) group; the extent of RWMA was smallest in the IWMI group, significantly larger in the AWMI group, and largest in the EAWMI with VA group. The location of the RWMA segments showed group-specific tendencies. For example, both coronal and sagittal apices were much more frequently involved in both the EAWMI with VA and the AWMI groups than in the IWMI group (100%, 87% and 0%, respectively, all P < 0.001). The results demonstrated that quantitative analysis of RWMA using 2DE in cases of MI is accurate and feasible.

Echocardiography↗
PubMed1992

Genetic engineering of high affinity anti-human colorectal tumour mouse/human chimeric antibody.

Two amino acids, tyrosine at position 96 and histidine at position 99 in the variable heavy chain (VH) CDR3 region of a mouse/human chimeric anti-TAG72 antibody cB72.3-1-3 were substituted with phenylalanine and asparagine respectively by site-directed mutagenesis technique. The expression vector mpSV2neo-EP1-Vm1-3-C gamma 1 containing mutant VH region fragments (Vm1-3) as well as the immunoglobulin enhancer (E), promoter (P1) and human genomic C gamma 1 region fragments, was transfected into a heavy-chain loss mutant cell line B72.3Mut(k). Mutant chimeric cB72.3m1-3 antibodies were purified from the transfectant supernates and compared based upon their binding affinity for the TAG72 antigen relative to that of the original cB72.3-1-3 antibody. The data show that a single amino acid substitution of histidine with asparagine at position 99 in VH CDR3 region contributes to four times increase in binding affinity for the TAG72 antigen. This suggests that the residue at position 99 in VH CDR3 region may play some role in antibody/antigen (B72.3/TAG72) interaction.

Animals↗
PubMed1992

Mass treatment of filariasis using DEC-medicated salt.

Diethylcarbamazine (DEC)-medicated salt was used to control bancroftian filariasis in 20 endemic counties and cities of Fujian Province in China. The population was 5,189,126 and the microfilaria (mf) rates were between 1.56 and 11.81%. The total dose of DEC was 6-10.5 g per person over a period of 2-4 months. Six to 9 months after treatment the mf rate was reduced to 0-0.57% with a mean of 0.07% (621/823,796). In 184 villages sampled one year post treatment the mf rate was 0.22% (371/171,067) and in 29 villages 2-4 years after treatment the mf rate was 0.05% (31/56,459). In a region of endemic Malayan filariasis, with a population of 67,778 and mf rate of 3.82-4.36%, treatment with DEC-medicated salt to a dosage of 3.2 g DEC per person was administered for 2 months. Six months after treatment the mean mf rate was reduced from 4.08 to 0.26% (10/3841). Filariasis in all the villages controlled with DEC-medicated salt reached the basic criteria of elimination (mf rate below 1%).

Animals↗
PubMed1991

Role of aspartic acid 38 in the cofactor specificity of Drosophila alcohol dehydrogenase.

Drosophila alcohol dehydrogenase (ADH), an NAD(+)-dependent dehydrogenase, shares little sequence similarity with horse liver ADH. However, these two enzymes do have substantial similarity in their secondary structure at the NAD(+)-binding domain [Benyajati, C., Place, A. P., Powers, D. A. & Sofer, W. (1981) Proc. Natl Acad. Sci. USA 78, 2717-2721]. Asp38, a conserved residue between Drosophila and horse liver ADH, appears to interact with the hydroxyl groups of the ribose moiety in the AMP portion of NAD+. A secondary-structure comparison between the nucleotide-binding domain of NAD(+)-dependent enzymes and that of NADP(+)-dependent enzymes also suggests that Asp38 could play an important role in cofactor specificity. Mutating Asp38 of Drosophila ADH into Asn38 decreases Km(app)NADP 62-fold and increases kcat/Km(app)NADP 590-fold at pH 9.8, when compared with wild-type ADH. These results suggest that Asp38 is in the NAD(+)-binding domain and its substituent, Asn38, allows Drosophila ADH to use both NAD+ and NADP+ as its cofactor. The observations from the experiments of thermal denaturation and kinetic measurement with pH also confirm that the repulsion between the negative charges of Asp38 and 2'-phosphate of NADP+ is the major energy barrier for NADP+ to serve as a cofactor for Drosophila ADH.

Alcohol Dehydrogenase↗