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Biomedical subjects

Z Chen

Publications and source records attributed to Z Chen.

At least 1,495 records · Page 83Linked to original sources
PubMed1991

[Role of rostral ventrolateral medulla in the "renzhong" induced pressor response in rabbits].

Experiments were performed on 14 rabbits locally anesthetized with procaine. Both vagus nerves were cut. The animals were immobilized with gallamine trithiodide and maintained by artificial ventilation. The effects of electrical stimulation of "Renzhong" area on arterial blood pressure and heart rate were observed before and after microinjection of kainic acid (KA) into rostral ventrolateral medulla (RVL). Electrical stimulation of "Renzhong" area could elicit a very marked increase in arterial blood pressure, before microinjection of KA into RVL. Bilateral microinjection of KA (0.5 microgram, an excitotoxin) into RVL could essentially abolish the pressor effect of stimulation of "Renzhong" area. However, bilateral microinjection of NS into RVL showed no effects on the pressor effect of stimulation of "Renzhong" area. These results suggest that RVL plays a key role in the pressor effect of "Renzhong" area stimulation.

Acupuncture Points↗
PubMed1991

Monoallelic deletions of the P53 gene in Chinese patients with chronic myelogenous leukemia in blastic crisis.

The configuration of the P53 tumor suppressor gene was investigated in 43 Chinese patients with chronic myelogenous leukemia (CML), 32 in chronic phase and 11 in blastic crisis. No obvious rearranged DNA band was detected in Southern blot patterns from patients at both stages of the disease. However, P53 gene deletion events were observed in 4 out of 11 cases in blast crisis. This finding was associated with a cytogenetically identifiable chromosome 17p deletion, iso(17q), in only one out of 4 cases.

Adult↗
PubMed1991

[A clinical trial of the secondary prevention of reinfarction with low dose aspirin].

Patients with acute myocardial infarction (AMI) admitted between 1986 and 1989 were divided into aspirin (ASA) group (216 cases) and control group (211 cases). In ASA group, 50 mg ASA was given daily to each case from the early stage of AMI and continuously after discharge (follow-up in OPD). In control group, no antiplatelet agents were administered during the follow-up period. The other therapies were comparable in both groups. The patients in both groups were scheduled for examination in the OPD every one to two months after discharge. Both groups were followed up until July, 1990. The follow-up periods in ASA group and control group were 19.4 +/- 12.6 vs 20.7 +/- 13.0 months respectively. There were 312 men in this study (175 in ASA group and 137 in control group). In men, incidence of reinfarction was reduced by 65% (P less than 0.001) and platelet aggregation was inhibited obviously in ASA group as compared to control group. However, there were no statistically significant differences of reinfarction and platelet aggregation between ASA group and control group in women. Thus, it is evident that low dose ASA is effective in preventing reinfarction and inhibiting platelet aggregation in men.

Aged↗
PubMed1991

Growth kinetics of Bu3 cells secreting HBsAg in microcarrier culture.

The genetically engineered mammalian cell (Bu3) secreting Hepatitis B surface antigen (HBsAg) was cultured on microcarriers semi-continuously. The growth model of Bu3 cells propagating on microcarriers, glucose consumption and lactate accumulation models were established. It is illustrated that the technology of anchorage-dependent Bu3 cell culture on microcarriers will give high yield and high HBsAg expression.

Animals↗
PubMed1991

[The development of DELFIA with novel tumor monoclonal antibodies E-11 and G-4].

Monoclonal antibodies E-11 and G-4 were purified by Sepharose 4B column chromatography and labelled with europium as tracer. The solid-phase antibodies were prepared by attaching pure E-11 and G-4 to polysterene strips. The supernatant of 8611 cell culture or perchloric acid extracts from ovarian cancer tissues provided standard antigens. The solid-phase sandwich-type DELFIAs for monoclonal antibodies E-11 and G-4 were thus established, and the resulting standard curves were extremely steep. The ratio of CPS in high-concentration tubes to CPS in the zero tube exceeded 300:1, indicating the very high sensitivity and accuracy of this method.

Antibodies, Monoclonal↗
PubMed1991

[The preparation of monoclonal antibody HI30-homoharringtonine liposomes (immunoliposomes) and targeting tests in vitro].

Liposomes encapsulating homoharringtonine were prepared using soybean phospholipids, egg yolk phospholipids and phospholipids from human red cell membrane, respectively. The quantity of homoharringtonine encapsulated by phospholipids from human red cell membrane was greater than that encapsulated by the other two types of liposomes, so this kind of phospholipid was used for further studies. The liposomes containing homoharringtonine (HH) were covalently coupled with HI30 (CD45). The mixture was separated by gel column chromatography. HI30-HH-liposomes demonstrated a sensitive targeting function with an immune activity equal to that observed with original HI30 in indirect immunofluorescence tests using the human cell line CEM-M3.

Antibodies, Monoclonal↗
PubMed1991

The retinoic acid alpha receptor gene is frequently disrupted in its 5' part in Chinese patients with acute promyelocytic leukemia.

The t(15;17)(q22;q11-q21) translocation, a hallmark for acute promyelocytic leukemia (APL), has recently been shown to disrupt the retinoic acid-alpha receptor (RARA) gene localized on band 17q21. Leukemic cell DNAs from 16 Chinese patients with APL were analysed by Southern blot hybridization with probes covering the 5' and the 3' parts of the gene. In ten patients, the breakpoints were concentrated within a 5.5 kb EcoRI fragment containing part of intron 1, whereas no rearrangement was detected in the six remaining patients. Genomic amplification of the RARA gene was observed in one case. When RNA was available (six patients), abnormal-sized RARA gene transcripts were observed. Interestingly, no rearranged transcript was found in cells from a patient during a 6-day treatment with all-trans retinoic acid, while bone marrow cells still possessed the translocation.

Adolescent↗
PubMed1991

[The preservation capacity of water and fertility of soilless cultivation substrate for Panax quinquefolium L.)].

The preservation capacity of water and fertility of several soilless cultivation substrates for Panax quinquefolium was compared in a large area. The data indicate that vermiculite mixed with sand (volume 1:1) is the most suitable soilless substrate for P. quinquefolium, for it is loose and features good preservation of fertility, water retaining, drainage, and air permeability. Timely analysis of nutrient contents in the substrates during cultivating period may serve as a guideline for correct application of fertilizer.

Panax↗
PubMed1991

An analysis of neuronal responses in nucleus centrum medianum to electrical stimulation of the superficial peroneal nerve.

Excitatory and inhibitory responses recorded extracellularly in neurons at various levels of the central nervous system induced by electrical noxious stimulation of peripheral nerves were frequently reported in studies on the mechanisms of acupuncture analgesia. However, the correlation between the responses and excitation of distinct afferent fibers was rarely investigated. The question whether the responses mentioned above are truly nociceptive in property is of significance to answer, and this is what we want to clarify in the present study. Sixty five neurons responding to electrical stimulation of the left superficial peroneal nerve were extracellularly recorded in the nucleus centrum medianum (CM) contralateral to the stimulation in 34 cats paralyzed with gallamine triethiodide and ventilated artificially under anaesthetics. Peristimulus histograms of the responses of CM neurons were plotted correspondingly, to the excitation of A delta and C-fibers, which was monitored by means of compound action potentials. To identify the nociceptive property of the responses ketamine or morphine was intravenously administered in some cases, capsaicin was topically applied at the superficial peroneal nerve proximal to the stimulated location in a few cases. Besides, the effect of electroacupuncture (EA) at Zusanli (St36) and Huantiao (GB30) points on the responses was observed. A total of 65 CM neurons recorded included 55 excited and 10 inhibited neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1991

[Effects of electroacupuncture at different points on nociceptive responses of the ventro-basal complex].

The purpose of the present study was to compare the effects of electro-acupuncture at different points on nociceptive responses of VB neurons. The experiments were carried out on rats (280-320g) anaesthetized with urethane (19/kg,i.p.). Single unit activities of VB neurons were extracellularly recorded by means of glass microelectrodes. Noxious stimulation was subcutaneously applied at the left ankle joint by inserting two stainless needles. The experiments were divided into three groups: EA. I, EA. II and EA. III. The corresponding points being selected for electroacupuncture in the above three groups were the left "Huantiao" (G30) point, the right "Huantiao" point and the left "Jianlian" (T14) point. The results showed that electroacupuncture at the points in the three groups all could inhibit the nociceptive responses of VB neurons, but electroacupuncture an the left "Huantiao" point (n = 11) was more effective than either at the right "Huantian" point (n = 9) or at the left "Jianliao" point (n = 10). There was a significant difference among the three groups. However, there was no significant difference between EA. II and EA. III. Thus, the results indicate that there is a relative specificity of points in acupuncture analgesia.

Acupuncture Points↗
PubMed1991

[Effects of morphine and electro-acupuncture on the time lock and not-time lock responses of cortical unit discharges evoked by nociceptive stimulation in cats].

In order to study the effects of morphine and electro-acupuncture(EA) on non-time-lock response (N-TLR) and time-lock respone (TLR) of nociceptive unit discharges. N-TLR was shown by interspike interval mean function (ISIMF) and TLR by normalized cross-covariance function (NCCVF) reflecting the relationship between stimulation and response. The results showed that the N-TLR elicited by the noxious stimulation appeared as a decrease of ISIMF. Which was depressed obviously by EA and morphine, but inhibitory effect of EA was more rapid than morphine, that both EA and morphine inhibited mainly the late peak of the NCCVF elicited by the noxious stimulation, but inhibitory effect of EA was more rapidly developing and more quickly recovering than that of morphine. The inhibitory effect of EA on the early peak was very little. From above results it was suggested that the P-ED elicited by the noxious stimulation could be inhibited by both EA and morphine, but the degree and the speed of inhibition were difference.

Animals↗
PubMed1991

Filariasis and its control in Fujian, China.

Epidemiological survey of filariasis in Fujian Province, China showed that malayan filariasis, transmitted by Anopheles lesteri anthropophagus was mainly distributed in the northwest part and bancroftian filariasis with Culex quinquefasciatus as vector, in middle and south coastal regions. Both species of filariae showed typical nocturnal periodicity. Involvement of the extremities was not uncommon in malayan filariasis. In contrast, hydrocele was often present in bancroftian filariasis, in which limb impairment did not appear so frequently as in the former. Hetrazan treatment was administered to the microfilaremia cases identified during blood examination surveys, which were integrated with indoor residual spraying of insecticides in endemic areas of malayan filariasis when the vector mosquito was discovered and with mass treatment with hetrazan medicated salt in endemic areas of bancroftian filariasis. At the same time the habitation condition was improved. These factors facilitated the decrease in incidence. As a result malayan and bancroftian filariasis were proclaimed to have reached the criterion of basic elimination in 1985 and 1987 respectively. Surveillance was pursued thereafter and no signs of resurgence appeared.

Animals↗
PubMed1990

A 25-kilodalton ubiquitin carrier protein (E2) catalyzes multi-ubiquitin chain synthesis via lysine 48 of ubiquitin.

Target protein multi-ubiquitination involving lysine 48 of ubiquitin (Ub) is known to occur during protein degradation in the ATP- and Ub-dependent proteolytic pathway (Chau, V., Tobias, J. W., Bachmair, A., Marriott, D., Ecker, D. J., Gonda, D. K., and Varshavsky, A. (1989) Science 243, 1576-1583). However, little is known about the enzymatic mechanism of multi-ubiquitination. We show that a purified Ub carrier protein, E2(25)K, catalyzes multi-Ub chain synthesis from purified Ub. Incubation of E2(25)K with Ub activating enzyme (E1), MgATP, and radiolabeled Ub (Mr = 8500) resulted in time dependent appearance of a "ladder" of radiolabeled Ub conjugates with molecular masses of 8.5n kDa, where n = 1, 2, 3, 4... (up to at least n = 10). The kinetics of this conjugative process were consistent with Ub2 acting as a steady-state intermediate. The putative Ub2 product of E2(25)K catalysis was purified and cleaved with a partially purified isopeptidase preparation. The sole cleavage product (Mr = 8500) had a tryptic digest identical to that of authentic Ub, confirming that the original conjugate was Ub2. Tryptic digestion of intact Ub2 gave products consistent with the existence of an isopeptide linkage between the COOH terminus of one Ub and Lys-48 of the other; this structure was confirmed by sequence analysis of the unique Ub2 tryptic fragment. Tryptic digestion of higher order Ubn adducts (n greater than or equal to 4) yielded fragments identical to those of Ub2, indicating that E2(25)K ligates successive Ub molecules primarily or exclusively via Lys-48. Although several other E2s supported synthesis of an apparent Ub2 adduct of undetermined linkage, only E2(25)K was capable of synthesizing multi-Ub chains from isolated Ub. Quantitative analysis of single turnovers showed that transfer from E2(25)K-Ub to Ub and Ub2 occurred with kappa 2 = 488 and 1170 M-1 min-1, respectively, at pH 7.3 and 37 degrees C. These results show that increasing the number of Ub molecules in a chain increases susceptibility to further ubiquitination by E2(25)K. Ub2 was a good substrate for activation by E1 and was readily transferred to E2(25)K. The labile E2(25)K-Ub2 adduct was catalytically active, and exhibited preference for Ub2 (versus Ub) as acceptor. These results suggest that E2(25)K may function as a multi-ubiquitinating enzyme in the Ub-dependent proteolytic pathway.

Amino Acid Sequence↗
PubMed1990

Sequence diversity in the 5' untranslated region of rabbit muscle phosphofructokinase mRNA.

DNA sequences of two full-length rabbit muscle phosphofructokinase (RMPFK) cDNAs (A and B) show identical coding sequence but heterogeneous 5' untranslated regions. cDNA-A is formed by removal of a 1.7 kb upstream intron while cDNA-B retains the 3' region of this intron. A 2.8 kb upstream sequence of RMPFK gene contains several features characteristic of housekeeping genes: high GC content (67%) at its 5' end, with 50 CpG sites; five Sp1 sites; and no functional TATA box. Comparison of the 5' sequences of the two RMPFK cDNAs and three human muscle PFK cDNAs (Nakajima, H., et al., (1990) Biochem. Biophys. Res. Com. 166, 637) suggests that a single splicing event occurs involving different splicing donor sites but the same splicing acceptor site, resulting in diversity in the upstream sequence. These observations suggest that transcription of muscle PFK gene may start at multiple sites, another feature of housekeeping genes.

Animals↗