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L M Liu

Publications and source records attributed to L M Liu.

At least 37 records · Page 2Linked to original sources
PubMed1998

Converting an integrated hospital formulary into an object-oriented database representation.

Controlled Medical Vocabularies (CMVs) have proven to be extremely useful in their support of the tasks of information sharing and integration, communication among various software applications, and decision support. Modeling a CMV as an Object-Oriented Database (OODB) provides additional benefits such as increased support for vocabulary comprehension and flexible access. In this paper, we describe the process of modeling and converting an existing integrated hospital formulary (i.e., set of pharmacological concepts) into an equivalent OODB representation, which, in general, we refer to as an Object-Oriented Healthcare Vocabulary Repository (OOHVR). The source for our example OOHVR is a formulary provided by the Connecticut Healthcare Research and Education Foundation (CHREF). Utilizing this source formulary together with the semantic hierarchy composed of major and minor drug classes defined as part of the National Drug Code (NDC) directory, we constructed a CMV that was eventually converted into its OOHVR form (the CHREF-OOHVR). The actual conversion step was carried out automatically by a program, called the OOHVR Generator, that we have developed. At present, the CHREF-OOHVR is running on top of ONTOS, a commercial OODB management system, and is accessible on the Web.

Databases as Topic↗
PubMed1997

Stress proteins are not induced in mammalian cells exposed to radiofrequency or microwave radiation.

The induction of stress proteins in HeLa and CHO cells was investigated following a 2 h exposure to radiofrequency (RF) or microwave radiation. Cells were exposed or sham exposed in vitro under isothermal (37 +/- 0.2 degrees C) conditions. HeLa cells were exposed to 27- or 2450 MHz continuous wave (CW) radiation at a specific absorption rate (SAR) of 25 W/kg. CHO cells were exposed to CW 27 MHz radiation at a SAR of 100 W/kg. Parallel positive control studies included 2 h exposure of HeLa or CHO cells to 40 degrees C or to 45 microM cadmium sulfate. Stress protein induction was assayed 24 h after treatment by electrophoresis of whole-cell extracted protein labeled with [35S]-methionine. Both cell types exhibited well-characterized responses to the positive control stresses. Under these exposure conditions, neither microwave nor RF radiation had a detectable effect on stress protein induction as determined by either comparison of RF-exposed cells with sham-exposed cells or comparison with heat-stressed or Cd++ positive control cells.

Animals↗
PubMed1997

The importance of delta and kappa opioid receptors in the property of thyrotropin-releasing hormone against hemorrhagic shock.

Many studies have demonstrated that thyrotropin-releasing hormone (TRH) produces various beneficial effects in the treatment of shock. TRH has been proposed to reverse the cardiovascular depression of endogenous opioid peptides. Nevertheless, it remains unknown whether opioid receptors are truly involved in this process. We designed experiments to study the importance of delta and kappa opioid receptors in the beneficial effects of TRH in hemorrhagic shock in rabbits and on opiate receptors following hemorrhagic shock in rats. The results indicated that TRH (50 micrograms, i.c.v.) significantly improved the mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), and the maximal rate of ventricular systolic pressure changes (+/- dp/dtmax) during hemorrhagic shock in rabbits. This TRH effect was abolished by pretreatment with ICI174,864 (50 micrograms, i.c.v.), a highly selective delta opioid receptor antagonist, but not by pretreatment with nor-binaltorphimine (Nor-BNI, 50 micrograms, i.c.v.), a highly selective kappa opioid receptor antagonist. The maximal binding capacity (Bmax) of brain delta and kappa opioid receptors significantly increased following hemorrhagic shock, but the receptor affinity (Kd) did not change. TRH (5 mg/kg, i.v.) decreased the number (Bmax) of brain delta opioid receptors significantly, but it did not influence the receptor affinity. TRH did not influence the Bmax or affinity of brain kappa opioid receptors. These findings suggest that opioid receptors play an important role in mediating the antishock property of TRH. TRH-induced down-regulation of the number of brain opioid receptors may be one of the important mechanisms by which TRH exercises its protective effects in the treatment of shock.

Animals↗
PubMed1996

Cancer risks among iron and steel workers in Anshan, China, Part I: Proportional mortality ratio analysis.

A standardized proportional mortality ratio (SPMR) study of 8,887 deaths during 1980-1989 among male workers in a large integrated iron-steel complex in Anshan, China, was conducted to provide clues to occupational risk factors. Accidents and cancer accounted for a higher proportion of deaths among the iron-steel workers than among the general male population (SPMR = 1.21; 95% CI = 1.12-1.31 and 1.14; 95% CI = 1.10-1.18, respectively). Among all workers, SPMRs were significantly elevated for stomach, lung, and colorectal cancers (SPMR = 1.37, 1.37, 1.38, respectively), but not other cancers. Risks of stomach cancer appeared to be highest among workers employed in jobs with exposure to iron and coal dust, whereas significant increases in colorectal cancer were seen for loading and other dusty jobs and for administrative and sedentary jobs without dust exposure. Risks of lung cancer appeared increased for a variety of jobs throughout the complex, especially those with probable high levels of exposure to polycyclic hydrocarbons and asbestos. Risk of esophageal cancer was significantly elevated for fire-resistant brick makers, and risk of nonmalignant respiratory disease was significantly elevated for those employed as furnace workers, foundry workers, and fire-resistant brick makers.

Accidents, Occupational↗
PubMed1996

Lifestyle, environmental pollution and lung cancer in cities of Liaoning in northeastern China.

Several studies were conducted in cities of Liaoning Province, one of the areas of China with heavy concentrations of industry, to investigate the effects of life-style factors and environmental pollutants on lung cancer causation. A case-control study involving 1249 lung cancer patients and 1345 population-based controls was conducted in 1985-1988 in Shenyang, the capital of Liaoning. Cigarette smoking was found to be the principal cause of lung cancer in this population, accounting for 55% of the disease in males and 37% in females. There was also a significant increase in lung cancer risk associated with an overall index of indoor air pollution due to coal-burning emission. The population attributable risk (PAR) for indoor air pollution was 13% for males and 17% for females. Risks were significantly increased for workers in the non-ferrous smelter (odds ratio (OR) = 2.6, 95% CI, 1.3-5.1), chemical and drug manufacturing (OR = 3.0, 95% CI, 1.0-8.0), and the glass and pottery industry (OR = 1.6, 95% CI, 1.0-2.5). Studies in the Anshan Iron-Steel Complex showed a significant excess of lung cancer for workers exposed to a variety of dusts. A standardized proportional mortality ratio (SPMR) study of 8887 deaths during 1980-1989 among male workers of the complex indicated a 37% excess risk of lung cancer compared to residents of the city. A nested case-control study was then conducted in that complex. A total of 610 cases of lung cancer diagnosed during 1987-1993 and 959 randomly selected controls from 196 993 active and retired employees of the complex were interviewed. Historical monitoring records for dust and benzo(a)pyrene (B(a)P) were collected from 1956-1992 to calculate cumulative exposure for each person. Results suggested that risks were increased for all occupations in which there was exposure to dusts, with the highest risks seen among coke oven workers (OR = 3.5, 95% CI, 2.0-6.4) and fire-resistant brick makers (OR = 2.9, 95% CI, 1.9-4.4). Significant dose-response patterns between cumulative total dust, cumulative total B(a)P and lung cancer risk were observed. The findings suggest that smoking and environmental pollution combine to account for elevated rates of lung cancer in cities of northeastern China.

Adenocarcinoma↗
PubMed1996

Effect of isothermal radiofrequency radiation on cytolytic T lymphocytes.

Previous in vitro studies provide evidence that RF electromagnetic radiation modulates proliferation of human glioma, lymphocytes, and other cell types. The mechanism of RF radiation cell proliferation modulation, as well as mechanisms for effects on other cell physiologic endpoints, are not well understood. To obtain insight regarding interaction mechanisms, we investigated effects of RF radiation exposure on interleukin 2 (IL-2) -dependent proliferation of cytolytic T lymphocytes (CTLL-2). After exposure to RF radiation in the presence or absence of IL-2 cells were cultured at various physiological concentrations of IL-2. Treatment effects on CTLL-2 proliferation were determined by tritiated thymidine incorporation immediately or 24 h after exposure. Exposure to 2450 MHz RIF radiation at specific absorption rates (SARs) of greater than 25 W/kg (induced E-field strength 98.4 V/m) induced a consistent, statistically significant reduction in CTLL-2 proliferation, especially at low IL-2 concentrations. At lower SARs, 2450 MHz exposure increased CTLL-2 proliferation immediately after exposure but reduced 24 h postexposure proliferation. RF radiation effects depended on the mitotic state of the cells at the time of exposure. Comparison of the effects of temperature elevation and RF radiation indicated significant qualitative and quantitative differences.

Animals↗
PubMed1995

[The changes in natriuretic peptide receptors (NP-R) in the lung and kidney in DOCA-salt hypertensive rats].

To elucidate the pathophysiological significance and the regulation of natriuretic peptide receptors (NP-R) in hypertension, we investigated the changes of NP-R in the lung, renal cortex and medulla using radioreceptor assay. We also examined the concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in the atria and ventricles and plasma ANP concentration by specific radioimmunoassays. Elevated plasma ANP level, decreased atrial ANP concentration and increased ventricular ANP and BNP contents were observed in the DOCA-salt group when compared with the control group (p < 0.01). The ratio of BNP/ANP in the ventricle of the DOCA-salt rats was 50% of the control rats. The elevated plasma ANP secreted from the heart seems to reflect a defensive compensatory mechanism to counteract hypertension, and that ANP is the major natriuretic peptide secreted from the cardiac ventricle in DOCA-salt hypertensive rats. Scatchard plot analysis revealed that the maximal binding capacities (Bmax) of NP-R of the lung and renal cortex in DOCA-salt rats were significantly decreased from 71.0 +/- 10.4 to 38.4 +/- 5.9 (p < 0.05) and from 32.7 +/- 1.8 to 21.7 +/- 0.4 (fmol/mg. protein) (p < 0.01) compared with those in the control rats. The values of Bmax of the renal medulla between the two groups were not different. There was no significant change in the apparent dissociation constant (Kd) in the lung, renal cortex and medulla between the two groups. A competitive binding study using 125I- alpha-rANP1-28 and C-ANF4-23, a biologically silent clearance receptor (C-receptor) specific ligand, revealed that C-receptors are abundantly present in the renal cortex, while a relatively small quantity of C-receptor was detected in the renal medulla. In the lung, a substantial amount of C-receptor was detected. In the DOCA-salt treated rats, C-receptors were decreased in the lung and renal cortex compared with the control rats. These results indicate that the down-regulation of NP-R, especially C-receptor, was induced in the lung and renal cortex when plasma ANP levels were elevated in DOCA-salt hypertensive rats. In conclusion, our results suggest that down-regulation of C-receptor in the lung and kidney contributes to maintaining higher plasma ANP levels and maybe responsible for the counter-regulatory role of endogenous ANP in DOCA-salt rats. Our results show that the down-regulation of NP-R in the lung was larger than that in the kidney, suggesting that the lung may play a dominant role in the regulation of the clearance of ANP through C-receptors in vivo.

Animals↗
PubMed1995

Absorbed energy distribution from radiofrequency electromagnetic radiation in a mammalian cell model: effect of membrane-bound water.

The spatial distributions of induced 27 or 2450 MHz radiofrequency (RF) electric fields (E-fields) and specific absorption rates (SARs) in a three-component spherical cell model (cytoplasm, membrane, extracellular space) were determined by Mie scattering theory. The results were compared to results for the same cell model but with 0.5 nm thick of bound water on the inner (cytoplasmic) and outer (extracellular) membrane surfaces (i.e., five-component cell model). The results provide insight regarding direct frequency-dependent RF radiation effects at the cellular level. Induced E-fields and SARs were calculated for two bound-water characteristic frequencies (400 or 1000 MHz) and ionic conductivities (1-1000 mS/m). In order to estimate the dependence of the results on bound water within the membrane per se, the model was revised to include bound water within the inner and outer membrane surfaces. The results were as follows: 1) on the x-axis, the y- and z-components of the induced E-field were of insignificant magnitude compared to the x-component for an incident E-field parallel to the x-axis; 2) the ratio of transmembrane E-fields induced by 2450 MHz vs. 27 MHz RF [i.e., Ex (2450 MHz)/Ex (27 MHz)] was 0.1; 3) for the three-component cell model, the corresponding SAR ratios [SAR (2450 MHz)/SAR (27MHz)] in the cytoplasm and extracellular space were 1.66 and 5.0, respectively; 4) the SAR rations [SAR (2450 MHz)/SAR (27 MHz)] for the cytoplasm and extracellular space for the five-component cell model were 1.66 and 5.0, respectively; 5) the ratio of the E-fields induced in the cytoplasmic and extracellular layers of bound water in the five-component cell model [E (2450 MHz)/ E (27Mhz)] were 0.62 and 0.63, respectively; 6) the SAR ratios [SAR (2450 MHz)/SAR (27 MHz)] for the cytoplasmic and extracellular bound-water layers were 66 and 65.3, respectively; and 7) variation of bound-water characteristic frequency, ionic conductivity, or bound-water incorporation inside the membrane surfaces, per se, did not significantly affect the E-field or SAR ratios. These results indicate that frequency-dependent nonuniformities may occur in the distribution of induced RF E-fields and SARs at the cellular level.

Animals↗
PubMed1995

Rat intestinal dendritic cells: immunostimulatory potency and phenotypic characterization.

Dendritic cells (DC) acquire antigens in peripheral tissues, transport them to lymph nodes and present peptides to T cells. DC are particularly good activators of resting T cells. Murine Langerhans' cells (LC) are efficient at endocytosing and processing antigens but are very weak immunostimulators. In culture LC lose the ability to process antigen and become potent immunostimulators. Other peripheral DC are not well characterized and it is not known if they are similarly weak immunostimulators. We isolated DC from rat Peyer's patches (PP) and lamina propria (LP) of the small intestine, from intestinal lymph (LDC) and mesenteric lymph nodes, and examined their ability to stimulate an allogeneic mixed leucocyte reaction (MLR). Freshly isolated LP DC and PP DC could stimulate a moderate MLR but fresh LDC were significantly more potent. After overnight culture, LDC did not change their potency but DC from LP and PP became as potent as LDC. In contrast, fresh lymph node DC stimulated a MLR or oxidative mitogenesis as efficiently as LDC. These results show that the weak immunostimulation of murine LC is not characteristic of all peripheral DC. We compared the phenotypes of DC from different sites before and after culture. Different populations of DC show marked phenotypic heterogeneity in the expression of surface markers, particularly Thy-1, CD2 and the iC3b receptor. PP and LP DC were similar to MLN DC in their expression of markers, but differed from LDC. After culture there were marked changes in DC surface marker expression and the differences between the populations were reduced. These observations suggest that the heterogeneity observed in fresh populations does not signify different stages of maturation but may represent activation.

Animals↗
PubMed1995

Effects of thyrotropin-releasing hormone on myocardial adrenoceptors and dopaminergic receptors following hemorrhagic shock in the rat.

Although studies have indicated that thyrotropin-releasing hormone (TRH) produces various beneficial effects following low flow conditions, it remains unknown whether this agent has any salutary effect on myocardial alpha- and beta-adrenergic and dopaminergic (DA) receptors following hemorrhagic shock. To study this, rats (220-280 g) were bled to a mean arterial pressure of 40 mmHg and maintained for 1.5 h following shock. TRH or an equivalent volume of normal saline was administered. Receptor binding assay was carried out in myocardial plasma membrane preparations at 15 and 45 min after TRH administration. The results indicate that the maximal binding capacity (Bmax) of myocardial alpha- and beta-adrenergic receptors and their affinity decreased significantly following hemorrhage. The Bmax of DA receptors was also reduced, while the affinity was not significantly affected by hemorrhagic insult. Administration of TRH (5 mg/kg body wt) at 1.5 h after the onset of hemorrhage, however, markedly increased the Bmax of myocardial beta-adrenergic and DA receptors. The decreased affinity of beta-adrenoceptors observed in hemorrhaged animals was also improved with TRH treatment. TRH did not, however, significantly affect the altered Bmax and affinity of alpha-adrenoceptors following hemorrhagic shock. These results suggest that TRH-induced upregulation of beta-adrenoceptor and DA receptor binding capacity and the enhanced affinity of beta-adrenoceptors may be one of the mechanisms by which TRH produces the beneficial effects following hemorrhagic shock.

Animals↗
PubMed1995

Antigen processing: cultured lymph-borne dendritic cells can process and present native protein antigens.

Langerhans' cells (LC) cultured for 1-3 days lose their ability to process native protein antigens but acquire the ability to stimulate resting T cells as assessed in an allogeneic mixed lymphocyte response (MLR). Lymph-borne dendritic cells (L-DC) are physiologically involved in the transport of antigens to lymph nodes but it is not known whether these cells lose the ability to process antigens in culture. To investigate this, we cultured L-DC derived from the intestine for 20-72 hr and tested their ability to process and present antigens. Our results show that these L-DC are able to present antigen to primed spleen T cells as effectively as fresh cells. To exclude the possibility that commercial ovalbumin (OVA) preparations contain peptides which might bind directly to major histocompatibility complex (MHC) molecules, OVA was filtered through Sephadex G50 and the peak fractions used as antigen. The results show that cultured L-DC are also able to present G50-filtered OVA efficiently to primed spleen T cells. More importantly, these G50-OVA-pulsed L-DC are able to prime naive T cells specifically in vivo. Chloroquine inhibited the ability of both fresh and cultured L-DC to present antigen to primed T cells but did not inhibit their ability to stimulate a MLR, indicating that processing was a necessary step for antigen presentation. Taken together, these results clearly show that cultured L-DC are active in processing and presenting native antigens and the hypothesis proposed for LC does not apply to rat lymph-borne dendritic cells. The physiological significance of these observations is discussed.

Animals↗
PubMed1995

[Effect of shenmai injection on sIL-2R NK and LAK cells in patients with advanced carcinoma].

Serum interleukin-2 receptor (sIL-2R) level activities of natural killer cell (NK) and lymphokine activated killer cell (LAK) cells were determined in 60 patients with advanced carcinoma (AC) before and after treatment with Shenmai injection (SMI), 40 healthy persons were taken as non-carcinoma control (NC). The results showed that: Serum sIL-2R level in AC were much higher than those in NC (P < 0.05) and activities of NK and LAK cells in AC were much lower than those in NC (P < 0.05) before treatment. There was no significant difference among gastric cancer, colonic carcinoma and lung cancer (P < 0.05). After treatment with SMI we also found that the level of sIL-2R in all patients were obviously lower (P < 0.05) while the activity of NK and LAK cells were significantly higher than that prior treatment (P < 0.05). Linear correlation was not found between sIL-2R and NK, LAK cells. These data suggested that the immune function was compromised in AC. The mechanism of the inhibitory effect of SMI on carcinoma might be related to the activity of biological response modifier.

Adult↗
PubMed1995

[Effects of Shenmai injection on immune function in stomach cancer patients after chemotherapy].

Sixty-three cases with stomach cancer were randomized and observed, the results showed that the count of T lymphocytes in chemotherapy combined with Shenmai injection (SMI) group increased, while in control group it decreased, the difference was significant (P < 0.05). The results also indicated that the count of OKT4 cells and the ratio of OKT4/OKT8 decreased after chemotherapy, but in SMI group both parameters increased in advence which were higher in the 4th week after chemotherapy than that before chemotherapy. However, the count of OKT1 cells and the ratio of OKT4/OKT8 were still in low level. Serum interleukin-2 receptor (sIL-2R) level also decreased (P < 0.05), while activities of natural killer cell (NK) and lymphokine activated killer cell (LAK) level increased (P < 0.05) in SMI group. Although the sIL-2R level had no change, both NK and LAK level decreased in control group. In addition, the difference of IgA, IgM, IgG level were not significant between these two groups. This suggested that SMI might improve human immune function to facilitate the chemotherapy of patients with stomach cancer.

Adenocarcinoma↗
PubMed1993

Antigen acquisition by dendritic cells: intestinal dendritic cells acquire antigen administered orally and can prime naive T cells in vivo.

In the rat, mesenteric lymphadenectomy allows collection of dendritic cells (DC) derived from the small intestine after cannulation of the thoracic duct. We prepared rats this way and administered antigens by oral feeding or intraintestinal injection. DC enriched from the thoracic duct lymph collected over the first 24 h from these animals are able to stimulate sensitized T cells in vitro and to prime popliteal lymph node CD4+ T cells after footpad injection, while B and T cells from the same thoracic duct lymph are inert in priming. 500 or less DC pulsed in vitro with antigen can prime T cells in vivo, whereas 100 times more B cells or macrophages pulsed in vitro are quite inert. 1 mg of ovalbumin administered orally is sufficient to load DC for in vivo priming of T cells. Antigen could not be detected directly in DC but was present in macrophages in the lamina propria. Direct presentation of antigen by DC to T cells was demonstrated by injecting F1 recipients with parental DC and showing restriction of T cell sensitization to the major histocompatibility complex of the injected DC. Antigen-bearing DC do not induce a detectable primary antibody response but a small secondary antibody response can be detected after a boosting injection. These results show that acquisition of antigens by DC in the intestine is very similar to what occurs in vitro or in other tissues, suggesting that there may be no special difference in antigen handling at mucosal surfaces. One implication of these results is that hypotheses designed to explain oral tolerance must take into account the presence of immunostimulatory, antigen-bearing DC in animals that have received oral antigens.

Administration, Oral↗