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Biomedical subjects

X Zou

Publications and source records attributed to X Zou.

At least 91 records · Page 5Linked to original sources
PubMed1995

C/EBP proteins activate transcription from the human immunodeficiency virus type 1 long terminal repeat in macrophages/monocytes.

Three binding sites for C/EBP proteins are found in the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) (V. M. Tesmer, A. Rajadhyaksha, J. Babin, and M. Bina, Proc. Natl. Acad. Sci. USA 90:7298-7302, 1993). We have determined the functional role of C/EBP proteins and C/EBP sites in regulating transcription from the HIV-1 LTR in monocytes/macrophages. Inhibition of endogenous C/EBP proteins, using either an excess of C/EBP binding sites or a trans-dominant negative inhibitor, demonstrated that C/EBP proteins are required for basal and activated levels of HIV-1 LTR transcription in the promonocytic cell line U937. Northern (RNA) blots and binding assays showed that NF-IL6 is the only known C/EBP family member which is increased when U937 cells are activated. Mutational analyses of the HIV-1 LTR showed that one C/EBP site is required for normal LTR transcription both before and after cellular activation and that the two 3' C/EBP sites are functionally equivalent. However, transcription from crippled HIV-1 LTRs lacking C/EBP sites can still be induced following activation of U937 cells. Several models are suggested for how elevated NF-IL6 may participate in an autostimulatory loop involving HIV infection, macrophage activation, cytokine expression, and HIV replication.

Base Sequence↗
PubMed1995

v-Abl activates c-myc transcription through the E2F site.

The v-abl oncogene of Abelson murine leukemia virus encodes a deregulated form of the cellular nonreceptor tyrosine kinase. v-Abl activates c-myc transcription, and c-Myc is an essential downstream component in the v-Abl transformation program. To explore the mechanism by which v-Abl activates c-myc transcription, a cotransfection assay was developed. We show that transactivation of a c-myc promoter by v-Abl requires the SH1 (tyrosine kinase) and SH2 domains of v-Abl; the C-terminal domains are not required for transactivation. The assay also identified the E2F site in the c-myc promoter as a v-Abl-responsive element. In addition, multimerized E2F sites were shown to be sufficient to confer v-Abl-dependent activation on a minimal promoter. This is the first identification of a v-Abl response element for transcriptional activation. v-Abl tyrosine kinase-dependent changes in proteins binding the c-myc E2F site were also demonstrated, including induction of a complex containing DP1, p107, cyclin A, and cdk2. Identification of v-Abl-dependent changes in E2F-binding proteins provides an important link between v-Abl, transcription, cell cycle regulation, and control of cellular growth.

Abelson murine leukemia virus↗
PubMed1995

[Postoperative management of crisis of myasthenia gravis: analysis of 20 patients].

From June 1983 to March 1992, 95 patients with of myasthenia gravis were treated with thyrmoma-thymectomy. Among them 90 patients were taken midsternotomy, and others standard lateral thoracotomy. All the patients had postoperative crisis of myathenia except one who had a cholinergic crisis. 12 patients (60%) belonged to type III and IV According to the Osserman's classification. The pathological findings showed that 17 patients had combined thyrmoma. The management for crisis was satisfactory with a success rate of 95%. The mortality rate was 5% (1/20) in early postoperative stage and 35% (7/20) in later stage, respectively. 12 patients survived for 2.5 to 10 years. Tracheotomy, mechanical ventilation adjustment, control of infection of the respiratory tract, and nourishment supports are the key measures for successful postoperative therapy and decrease of mortality.

Adolescent↗
PubMed1994

Ab-interno sclerostomy using a goniodiathermy instrument.

We describe the use of a new instrument designed to create a simultaneous goniopuncture with diathermy using an ab-interno technique. The goniodiathermy ab-interno procedure was first performed on three eyes of three cynomolgus monkeys. Intraocular pressure (IOP) assessment and histologic examination were performed over a 10-day period. A functioning filtration bleb with a patent sclerostomy was achieved in all of the experimental eyes. A pilot study involving four eyes of four glaucoma patients also was performed. Of these four, successful long-term functioning filtration areas with adequate lowering of IOP were achieved in only two. The remaining two required further surgical intervention. Although combining goniopuncture and diathermy into a one-step ab-interno procedure proved successful in the primates studied, the preliminary use of this new instrument as a method of creating a filter in humans raises questions regarding its clinical usefulness.

Adolescent↗
PubMed1993

Heteronuclear nuclear magnetic resonance studies of cobalt corrinoids. 15. The structure of glutathionylcobalamin: a 1H and 13C two-dimensional nuclear magnetic resonance study at 600 MHz.

Glutathionylcobalamin (GSCbl), the complex formed between glutathione (GSH, gamma-glutamylcysteinylglycine) and aquacobalamin (H2OCbl), has been implicated as an intermediate in the pathway for the formation of the cobalamin coenzymes. In chemical model studies, GSCbl has been shown to be a substrate for methylcobalamin formation in the presence of S-adenosylmethionine and a thiol reductant. Although GSCbl was first described in 1964, the structure of this compound, particularly the site of GSH coordination, has been unknown. GSCbl was prepared by reacting GSH (5-fold molar excess) with H2OCbl in 0.1 M sodium phosphate (pH 6.5) and was purified by gel-permeation chromatography on a Bio-Gel P2 polyacrylamide column. By use of a combination of homonuclear [homonuclear J-correlated spectroscopy (COSY), homonuclear Hartmann-Hahn spectroscopy (HOHAHA), and absorption-mode nuclear Overhauser effect spectroscopy (NOESY)] and inverse detected heteronuclear [1H-detected heteronuclear multiple-quantum coherence (HMQC) and 1H-detected multiple-bond heteronuclear multiple-quantum coherence (HMBC) spectroscopies] two-dimensional NMR methods at 600 MHz, the complete 1H and 13C NMR spectra of GSCbl have now been assigned. Comparison of the 1H and 13C NMR chemical shifts of the GS moiety of GSCbl to those of free GSH and GS- shows that by far the largest differences occur at the cysteine alpha and beta positions. This result strongly suggests that GSH is coordinated to the cobalt atom in GSCbl via the cysteine sulfur atom.

Carbon Isotopes↗
PubMed1993

Canventol inhibits tumor promotion in CD-1 mouse skin through inhibition of tumor necrosis factor alpha release and of protein isoprenylation.

A synthetic compound named canventol, 2-isopropyl-4-isopropylidencyclohex-2-ene-1-ol, inhibited tumor promotion of okadaic acid on mouse skin initiated with 7,12-dimethylbenz(a)anthracene in two-stage carcinogenesis experiments more strongly than sarcophytol A, isolated from a soft coral, although canventol has a simpler structure than sarcophytol A. Their mechanisms of action were studied based on our recent evidence that tumor necrosis factor alpha release induced by okadaic acid is an essential mechanism of tumor promotion. Canventol inhibited mouse tumor necrosis factor alpha release from BALB/3T3 cells less strongly than sarcophytol A, indicating that canventol has additional activity. Canventol inhibited isoprenylation of proteins with various molecular weights, such as M(r) 22,000, 17,000, and 13,000, whereas sarcophytol A did not show significant inhibition. Thus, a potent anticarcinogenic activity of canventol is mediated through the inhibitory bifunctions of tumor necrosis factor alpha release and of protein isoprenylation. Since canventol is less toxic to cells than sarcophytol A, these bifunctions are useful markers for screening for new cancer chemopreventive agents.

3T3 Cells↗
PubMed1993

[Role of musculocutaneous nerve in the relationship between "chutse" acupoint and heart].

Ligating fourty eight rabbits left ventricular branch of coronary artery made model of acute myocardial infarction (AMI) with indices of ECG and size of AMI. They were divided at random into four groups: "Chutse" acupoint group, cutting musculocutaneous nerve of "Chutse" acupoint group, cutting musculoutaneous nerve group, control group. Results showed that there is no role in laser acupuncture at "Chutse" acupoint for reducing myocardial injury and size of AMI after cutting musculocutaneous nerve of "Chutse" acupoint. It is illustrated that the musculocutaneous nerve might play an important role in the relationship between "Chutse" acupoint and heart.

Acupuncture Points↗
PubMed1992

Volatile N-nitrosamines in salted fish samples from high- and low-risk areas for NPC in China.

Four carcinogenic volatile nitrosamines (N-dimethylnitrosamine, NDMA; N-diethylnitrosamine, NDEA; N-nitrosopyrroline, NPYR; and N-nirosopiperilidine, NPIP) were screened in twenty specimens of salted fish collected from areas in China with different nasopharyngeal carcinoma (NPC) mortality rates. The highest NDMA, NDEA and total N-nitrosamine contents (322.92, 50.27 and 373.19 micrograms/kg, respectively) were found in the samples from Sihui, one of the areas with highest NPC mortality. The lowest contents (12.64, 7.65 and 20.29 micrograms/kg, respectively) were seen in the samples from Shanghai, the area with the lowest mortality from NPC in the study. These results confirm that there are appreciable levels of nitrosamines in the salted fishes consumed by residents in high-risk areas of NPC in China.

Animals↗
PubMed1991

MR angiography without subtraction.

A new NMR method for producing angiograms with strong suppression of the static spin signal and without the need for subtraction is described and demonstrated. A velocity-selective pulse sequence was implemented whereby the magnetization of all stationary spins is driven to the -z axis and is not detected, while maximizing the signal intensity of the moving spins. A theory of the method is presented and gives good agreement with experimental results obtained on a flow phantom. It is shown theoretically and experimentally that high-quality velocity-independent angiograms of the head and neck can be obtained with strong suppression of static spin signal when TR approximately T1. The method can be extended to produce three-dimensional angiograms.

Angiography↗
PubMed1991

Multiecho, spin-echo sequence to eliminate unwanted echoes.

Two types of artifacts--a mirror-reversed image about the phase-encode direction and a wave-like intensity variation across the image--may appear when using a conventional multiecho spin-echo sequence. We describe and demonstrate a new method, which eliminates such artifacts, using only one excitation per phase-encoding step and without the need for spoiler gradients.

Electromagnetic Phenomena↗
PubMed1991

[Central neural mechanism underlying pressor response to excitation of locus coeruleus in rats].

Experiments were done on urethane anesthetized, tubocurarine immobilized and artificially ventilated rats and the following results were observed: (1) Injection of sodium L-glutamate (Glu) into locus coeruleus (LC) could evoke a pressor response, but heart rate was not significantly affected; while depressor and bradycardia effects were observed when injecting into closely adjacent areas. (2) The LC-pressor response decreased after a brain transection caudal to nucleus paraventricularis was made but remained unchanged if the transection was rostral to the nucleus; The LC-pressor response could also be attenuated by preinjection of phentolamine propranolol or atropine respectively into the rostral ventrolateral medulla (RVL). The above results suggest that LC-pressor response is not only mediated by RVL, but also by nucleus paraventricularis.

Animals↗
PubMed1990

[Comparative study of cerebral infarction treated with acupuncture at 6 acupoints of yang meridian and calan].

UNLABELLED: This article reports the curative effects of acupuncture on 6 acupoints of Yang meridian in treating 32 cases of cerebral infarction in comparison with another 31 cases treated with calan tablets 55 out of 63 patients have been diagnosed as cerebral infarction by computer tomography. Diagnosis of 8 cases relied on history, symptoms, signs together with cerebrospinal fluid examination. Patients were divided randomly into two treatment groups: acupuncture group and calan tablet group. Therapeutic method: (1) For acupuncture group, main acupoints consisted of Jianyu (L.I. 15), Quchi (I. I. 11), Hegu (L. I.4) in the upper extremity and Huantiao (G. B. 30), Yanglingquan (G. B. 34), Guangming (G. B. 37) in the lower extremity. According to the syndrome differentiation, Taichong (Liv. 3), Fengchi (G. B. 20), Tianshu (St. 25), Fenglong (St. 40), Zusanli (St. 36), Sanyinjiao (Sp. 6), Taixi (K. 3) were added. The lifting and thrusting was manipulated. The needles were retained for 30 minutes after the patient felt local sourness, distension and heaviness. Acupuncture was carried out every day for 6 weeks. (2) For calan tablet group, calan tablet 5 mg was administered 3 times a day for the same treatment session as the former group. RESULT: The total effective rates were 93. 75% and 83.87% respectively. The therapeutic effect in the acupuncture group was much better than that in the calan tablet group (P less than 0.05). The majority of hemorheological indices of patients in two groups were obviously higher than those of the normal in the same age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Points↗
PubMed1988

Effects of praeruptorin C and E isolated from 'Qian-Hu' on swine coronary artery and guinea-pig atria.

Praeruptorin C and E isolated from Peucedanum praeruptorum Dunn. decreased the maximum contractile effect of Ca2+ in potassium-depolarized swine coronary strips and shifted the concentration-response curve to the right in a non-parallel manner. The calcium antagonistic activity of praeruptorin C and E expressed as pD'2 value was 5.7 and 5.2, respectively. Nifedipine, with a pD'2 value of 6.88, was used as a known calcium antagonistic drug to compare the potency of the drugs studied. The relaxation induced by praeruptorin C was concentration-dependent and the IC50 value was 79 microM. Praeruptorin C also reduced the maximum contractile response and shifted the concentration-response curve for calcium to the right in a non-parallel manner in potassium-depolarized guinea-pig left atria (pD'2 = 5.52) but its potency was much less than that of nifedipine (pD'2 = 7.19). The results suggest that praeruptorin C and E relaxed swine coronary artery and decreased contractility in guinea-pig left atria. These effects are similar in many respects to those displayed by drugs that have calcium entry blocking activity.

Animals↗