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Biomedical subjects

X Guo

Publications and source records attributed to X Guo.

At least 433 records · Page 24Linked to original sources
PubMed1993

Production of cytokines and PGE2 and cytotoxicity of stimulated bone marrow macrophages after thermal injury and cytotoxicity of stimulated U-937 macrophages.

Bone marrow-derived macrophages from normal and burned rats were cultured for one and four days in the presence of LPS, PHA, or opsonized zymosan as activators, and the supernatants were assayed for the inflammatory mediators TNF, IL-6, and PGE2 and the cells assayed for cytotoxicity. The macrophages responded differently to the various stimuli regarding cytotoxicity and the production of mediators, perhaps implicating the complement receptor CR1 in TNF production and the LPS receptor CD14 or the PHA lectin receptor in IL-6 and PGE2 production and for cytotoxicity. The response of the cells also depended on culture time and postburn time; in addition, macrophages from burned and unburned animals responded differently, depending on postburn day and the type of stimulus. TNF production was generally higher for one-day compared to four-day cultures (i.e., TNF was disappearing in the cultures), but IL-6 and PGE2 production was greater in four-day cultures. The results of this study suggest that thermal injury can contribute to the development of inflammatory and cytotoxic macrophages from bone marrow progenitor cells.

Animals↗
PubMed1993

Antitumor agents. 126. Novel 4 beta-substituted anilino derivatives of 3',4'-O,O-didemethylpodophyllotoxin as potent inhibitors of human DNA topoisomerase II.

A series of derivatives of 3',4'-O,O-didemethylpodophyllotoxin have been synthesized and evaluated for their inhibitor activity against neoplastic cell growth (KB) and against human DNA topoisomerase II as well as for their activity in causing cellular protein-linked DNA breakage. The results show that the compounds possessing a 4 beta-anilino moiety either unsubstituted or substituted at the para (F, COOCH3, COCH3, CN, CH2CN, NO2) or meta (OH) positions or with an ethylenedioxy moiety showed the same or greater activity than etoposide in causing cellular protein-linked DNA breakage and in inhibiting DNA topoisomerase II. However, compared to the corresponding 4'-O-demethyl analogues, the 3',4'-O,O-didemethyl compounds have a similar potency in inhibition of DNA topoisomerase II but are less active in causing cellular protein-linked DNA breakage. Complete correlation between the three biological activities--cytotoxicity, inhibition of DNA topoisomerase II, and induction of protein-linked DNA breakage--was also not observed. This supports the possibility that the biological determinants of action among these compounds may be different.

Antineoplastic Agents↗
PubMed1993

Oxysterols inhibit gap junctional communication between rat hepatocytes in primary culture.

Several oxysterols were examined for their effect on gap junctional communication between rat hepatocytes in primary culture. 25-Hydroxycholesterol, 22(S)-hydroxycholesterol and 7 beta-hydroxycholesterol, in decreasing order of potency, markedly inhibited gap junctional communication. In contrast, 7-ketocholesterol showed no inhibitory effect. The inhibition of gap junctional communication by oxysterols was not a consequence of changes in cell viability, as measured by lactate dehydrogenase leakage and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction activity. The addition of exogenous cholesterol to the culture medium did not abolish the effect of 25-hydroxycholesterol, suggesting that the capacity of oxysterols to inhibit gap junctional communication is independent of their inhibitory effect on cholesterol synthesis. We suppose that inhibition of gap junctional communication may be an early sign of oxysterols-induced toxicity on hepatocytes.

Animals↗
PubMed1993

[Effect of yin and qi tonifying herbs on hyperthyroid model of yin-deficient rats].

The article reports the effect of Yin and Qi tonifying herbs (Radix Rehmanniae, Radix Ophiopogonis and Pseudostellaria Heterophylla) on hyperthyroid model of Yin-deficient rats. The model rats were made Yin-deficient by injecting thyroxine. Observation showed that after injection, indexes such as anus temperature, oxygen consumption, weight, diet, activity, general conditions, triiodothyronine (T3) and thyroxine (T4) in serum were markedly changed. It is thus suggested that the Yin and Qi tonifying mixture of the above three herbs can regulate and correct Yin-deficiency in hyperthyroid model of Yin-deficient rats.

Animals↗
PubMed1993

[A retrospective analysis of continuous cervical epidural block].

This article reviews 763 patients who underwent continuous cervical epidural block (CCEB) in our hospital during the past ten years. We analyzed the factors causing complications of CCEB and the respiratory and hemodynamic inhibition caused by different concentrations of local anesthetics. From the study, it is concluded that CCEB has obvious advantages, such as mild respiratory and hemodynamic inhibition, satisfactory analgesia, no air pollution and low cost. On the other hand, CCEB requires highly skilled manipulation during epidural puncture and catheterization, careful intraoperative management and appropriate local anesthetics. The question of how to eliminate the intraoperative traction reaction needs further study.

Adolescent↗
PubMed1993

Treatment of strain of the infrapatellar fat pad by manipulation--observation of therapeutic effect in 117 cases.

The present group comprises 117 cases of strain of the infrapatellar fat pad. The treatment effected a 100% cure in the mild and moderate types of the cases. In the severe cases suffering from such accompanying conditions as traumatic arthritis, the rate of effectiveness reached 100%, with all symptoms and signs becoming markedly alleviated. The treatment is considered a method of the first choice in handling strain of the infrapatellar fat pad, and also a good method for treating traumatic arthritis of the knee and malacia of the patella.

Acupuncture Points↗
PubMed1993

[A case-control study of the etiology of laryngeal cancer in Liaoning Province].

A cases-control study of laryngeal cancer was conducted in Liaoning province between 1991.1-1992.4 among 100 subjects with newly diagnosed cancer and 100 controls. The results of one factor analysis, odd ratio (OR), and conditional logistic regression indicated that smoking was the first significant risk factor for laryngeal cancer with an OR value 16.8, in which tobacco smoking was at the first place with an OR value 30.4. Other factors such as alcoholic indulgence, insufficient intake of vegetable and fruits in winter and spring, air pollution in room and working environment and fatigue of vocal cords were strongly associated with the occurrence of laryngeal cancer.

Alcohol Drinking↗
PubMed1993

[The precursors and effectors of human lymphokine-activated killer (LAK) cells].

Natural killer cells were enriched in the second fraction (F2) of discontinuous Percoll density gradients from human PBL after centrifugation, whereas T lymphocytes were enriched in F4. The cytotoxicity against K562 by F2 LAK (F2 cells activated by rIL2) was higher than that of F2 cells. F2 LAK also acquired the ability to lyse NK-resistant tumor cell lines and noncultured lung cancer cells (6 out of 9 cases). All these activities of F2 LAK cells were significantly higher than those of F4 LAK cells. Besides, F2 LAK exhibited higher level of lysis against noncultured lung cancer cells than did LAK derived from PBL. Enzyme-labeled immunocytochemistry staining showed that the number of CD16+ and CD8+ cells in F2 was much more than that in F4. So the higher lytic ability of F2 LAK might come from two kinds of precursors: CD16+ typical NK cells and MHC unrestricted CD8+, NK-like' cytotoxic T lymphocytes. The number of CD4+ cells in F4 was much more than that in F2. They shouldn't be the precursors of LAK cells, otherwise the lytic ability of F4 LAK should be higher than that of F2 LAK. After being cultured with rIL2 for 3 days, F2 cells exhibited proliferative response. But the percentage of CD16+ and CD8+ cells in F2 LAK did not change much, and remained much higher than that in F4 LAK. So the effector cells of short-term cultured LAK might be the activated CD16+ NK cells and CD8+, NK-like' cytotoxic T lymphocytes as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1993

Osteopontin: a protein with diverse functions.

In this review most of the various known, suspected, or postulated functions of osteopontin, a secreted highly acidic phosphoprotein, are discussed in terms of what we currently know about the protein. These include 1) binding of OPN both to cells via a GRGDS cell adhesion sequence that recognizes the alpha v beta 3 integrin and to extracellular matrix components via poorly characterized motifs, 2) regulation of the formation and remodeling of mineralized tissue, 3) recruiting and stimulating macrophages and lymphocytes as part of a nonspecific response to microbial infections, 4) multiple interactions with Ca2+ that likely influence OPN protein conformation and may be important in Ca(2+)-mediated or Ca(2+)-dependent processes, 5) inhibiting the growth of calcium oxalate crystals by disruption of the growing crystal lattice, 6) effects on gene expression, Ca2+ regulation, and nitric oxide production, and 7) involvement in cell migration. OPN production is frequently augmented when cell signaling pathways are activated by any of a variety of stimuli, for example in cancer cells.

Amino Acid Sequence↗
PubMed1993

The nutrition transition in China: a cross-sectional analysis.

Diets and activity patterns are changing rapidly in low-income countries, and problems of undernutrition and overnutrition commonly exist side by side. China has conquered problems of food scarcity at the national level and has undergone a remarkable transition in the structure of its diet in the last decade. In this paper, we use data from the 1989 China Health and Nutrition Survey and national data from the State Statistical Bureau to explore China's recent history with respect to nutrition and to identify patterns of under- and overnutrition. In particular, we see that higher income levels, particularly in urban areas, are associated with consumption of a diet higher in fat and with problems of obesity. At the same time, undernutrition is a problem in important segments of Chinese society. There is a need for the Chinese government to consider ways to address these problems of deficit and excess jointly.

Adolescent↗
PubMed1992

Regulated temporal and spatial expression of the calcium-binding proteins calcyclin and OPN (osteopontin) in mouse tissues during pregnancy.

In situ hybridization and northern/slot blot analyses were used to quantify the expression of calcyclin (2A9, 5B10), osteopontin (opn, secreted phosphoprotein, 2ar) and calmodulin mRNAs in mouse tissues that support pregnancy. High-to-moderate levels of the mRNAs of all three genes were detected at discrete locations in the uterus, decidua and placenta as a function of gestation time. Calmodulin expression was constant in these tissues; calcyclin mRNA was high during early pregnancy and declined after day 8-9 of gestation; and opn mRNA was undetectable before day 7, with maximal levels on days 9-12 in each of these tissues. Calcyclin, but not opn, expression was also observed in the chorioamnion after day 12. Calcyclin was expressed throughout the decidua on day 8 but became restricted to the primary (antimesometrial) decidual zone and decidua lateralis on day 9, and the decidua capsularis after day 9. By contrast, opn mRNA was localized on day 9 to the mesometrial triangle, which contains a large population of granulated metrial gland cells, and to the decidua basalis. These two genes may serve as markers for the two types of decidual tissue. We suggest that one function of OPN, which may be an indicator of cells in the decidua that have a bone marrow genealogy, is to mediate the flux of calcium from the maternal circulation to the developing embryo.

Animals↗
PubMed1992

Antitumor agents, 130, Novel 4 beta-arylamino derivatives of 3',4'-didemethoxy-3',4'-dioxo-4-deoxypodophyllotoxin as potent inhibitors of human DNA topoisomerase II.

A series of ortho-quinone analogues 1-28 of podophyllotoxin possessing various C-4 beta-aniline moieties have been synthesized and evaluated for their inhibitory activity against human DNA topoisomerase II, their activity in causing cellular protein-linked DNA breakage, and their cytotoxicity against KB cells. Compounds 8-12, 15, 19, and 23-28 are better than or comparable to etoposide in their inhibition of the human DNA topoisomerase II, while compounds 8-10 and 22 are comparable to or more potent than etoposide in causing DNA breakage. There is an apparent lack of correlation between cytotoxicity and the ability of these compounds to cause protein-linked DNA breaks or inhibit DNA topoisomerase II. This suggests that in addition to the mechanism of the topoisomerase II involving DNA breakages, other mechanisms of action, such as the radical mechanism or the direct adduct formation of the ortho-quinone with DNA or protein, may also involve and account for the apparent KB cytotoxicity. Two different modes of DNA topoisomerase II inhibition for 8-28 were proposed.

Antineoplastic Agents, Phytogenic↗
PubMed1992

[Feed-back regulation of presynaptic D2 receptors blockaded by l-stepholidine and l-tetrahydropalmatine].

The activity of tyrosine hydroxylase by accumulation of L-dopa content in the striatum under decarboxylase inhibitor (benserazide, 400 mg.kg-1) was measured by HPLC-ECD to ascertain whether l-SPD possesses an agonistic or antagonistic effect on D2 receptor subtype. The accumulated L-dopa content was increased with 1,4-butyrolactone (BL, 750 mg.kg-1) to 1.8 +/- s 0.6 micrograms.g-1 in rat striatum. After the rats were ip l-SPD 5 mg.kg-1 or l-tetrahydropalmatine (l-THP) 10-20 mg.kg-1, the increment of L-dopa level was much more than that in the BL group (P < 0.01) in a dose related manner. On the contrary, apomorphine (ip 5 mg.kg-1) abolished the accumulation of L-dopa induced by BL. Furthermore, l-SPD and l-THP not only reversed the negative feed-back regulation by apomorphine on the accumulated level of L-dopa, but also increased this level over the accumulation by BL. These results showed that l-SPD and l-THP do possess the antagonistic effect on presynaptic DA receptor (D2) without agonistic effect.

Alkaloids↗